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Sample records for 10exp 4 sq

  1. Measurements of Local Heat Transfer and Pressure on Six 2-Inch-Diameter Blunt Bodies at a Mach Number of 4.95 and at Reynolds Numbers Per Foot up to 81 x 10(exp 6)

    NASA Technical Reports Server (NTRS)

    Cooper, Morton; Mayo, Edward E.

    1959-01-01

    Measurements of the local heat transfer and pressure distribution have been made on six 2-inch-diameter, blunt, axially symmetric bodies in the Langley gas dynamics laboratory at a Mach number of 4.95 and at Reynolds numbers per foot up to 81 x 10(exp 6). During the investigation laminar flow was observed over a hemispherical-nosed body having a surface finish from 10 to 20 microinches at the highest test Reynolds number per foot (for this configuration) of 77.4 x 10(exp 6). Though it was repeatedly possible to measure completely laminar flow at this Reynolds number for the hemisphere, it was not possible to observe completely laminar flow on the flat-nosed body for similar conditions. The significance of this phenomenon is obscured by the observation that the effects of particle impacts on the surface in causing roughness were more pronounced on the flat-nosed body. For engineering purposes, a method developed by M. Richard Dennison while employed by Lockheed Aircraft Corporation appears to be a reasonable procedure for estimating turbulent heat transfer provided transition occurs at a forward location on the body. For rearward-transition locations, the method is much poorer for the hemispherical nose than for the flat nose. The pressures measured on the hemisphere agreed very well with those of the modified Newtonian theory, whereas the pressures on all other bodies, except on the flat-nosed body, were bracketed by modified Newtonian theory both with and without centrifugal forces. For the hemisphere, the stagnation-point velocity gradient agreed very well with Newtonian theory. The stagnation-point velocity gradient for the flat- nosed model was 0.31 of the value for the hemispherical-nosed model. If a Newtonian type of flow is assumed, the ratio 0.31 will be independent of Much number and real-gas effects.

  2. Laboratory Demonstration of Phase Induced Amplitude Apodization (PIAA) Coronagraph with Better than 10(exp -9) Contrast

    NASA Technical Reports Server (NTRS)

    Kern, Brian; Guyon, Olivier; Kuhnert, Andreas; Niessner, Albert; Martinache, Frantz; Balasubramanian, Kunjithapatham

    2013-01-01

    We present coronagraphic images from the Phase Induced Amplitude Apodization (PIAA) coronagraph on NASA's High Contrast Imaging Testbed (HCIT) at the Jet Propulsion Lab, showing contrasts of 5x10(exp -1) averaged from 2-4 lambda/D, in monochromatic light at 808 nm. In parallel with the coronagraph and its deformable mirror and coronagraphic wavefront control, we also demonstrate a low-order wavefront control system, giving 100 x rms suppression of introduced tip/tilt disturbances down to residual levels of 10(exp -3) lambda/D. Current limitations, as well as broadband (10% fractional bandpass) preliminary results are discussed.

  3. 4-sq cm CuInGaSe2 based solar cells

    NASA Astrophysics Data System (ADS)

    Devaney, W. E.; Stewart, J. M.; Chen, W. S.

    Polycrystalline thin-film solar cells with the structure ZnO/CdZnS/CuInGaSe2 have been fabricated with larger single-cell areas than have been previously reported. A cell with an area of 4 sq cm has been made with an AM1.5, 100 mW/sq cm total area conversion efficiency of 11.1 percent (12.0 percent active area) and an AM0 conversion efficiency of 10.0 percent (10.9 percent active area). The CuInGaSe2 layer had a gallium to indium ratio of 0.26:0.74 with a bandgap of approximately 1.15 eV. The cells use an isolated tab design for the negative (grid) contact, demonstrating the ability to pattern the semiconductor layers. Such CuInGaSe2-based cells may be suitable for large-area terrestrial applications and for single-junction space cell applications.

  4. Fabrication and performance analysis of 4-sq cm indium tin oxide/InP photovoltaic solar cells

    NASA Technical Reports Server (NTRS)

    Gessert, T. A.; Li, X.; Phelps, P. W.; Coutts, T. J.; Tzafaras, N.

    1991-01-01

    Large-area photovoltaic solar cells based on direct current magnetron sputter deposition of indium tin oxide (ITO) into single-crystal p-InP substrates demonstrated both the radiation hardness and high performance necessary for extraterrestrial applications. A small-scale production project was initiated in which approximately 50 ITO/InP cells are being produced. The procedures used in this small-scale production of 4-sq cm ITO/InP cells are presented and discussed. The discussion includes analyses of performance range of all available production cells, and device performance data of the best cells thus far produced. Additionally, processing experience gained from the production of these cells is discussed, indicating other issues that may be encountered when large-scale productions are begun.

  5. An Atomic Clock with 10 (exp -18) Instability

    DTIC Science & Technology

    2013-09-13

    from the effects of strong initial density fluctuations in quench up experi ments and finite temperature (20). The space time dependence of the...experimental tools to address exciting topics in cosmology and gravitational physics such as Hawking radiation (13) or Unruh effect (27). References...3.2 x 10- 16/y’t (red solid lile). The blue dashed line represents the estimated combined instabiliy contributions from the Dick effect (1.4 x 10-16

  6. A vacuum (10(exp -9) Torr) friction apparatus for determining friction and endurance life of MoSx films

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Honecy, Frank S.; Abel, Phillip B.; Pepper, Stephen V.; Spalvins, Talivaldis; Wheeler, Donald R.

    1992-01-01

    The first part of this paper describes an ultrahigh vacuum friction apparatus (tribometer). The tribometer can be used in a ball-on-disk configuration and is specifically designed to measure the friction and endurance life of solid lubricating films such as MoS(x) in vacuum at a pressure of 10 exp -7 Pa. The sliding mode is typically unidirectional at a constant rotating speed. The second part of this paper presents some representative friction and endurance life data for magnetron sputtered MoS(x) films (110 nm thick) deposited on sputter-cleaned 440 C stainless-steel disk substrates, which were slid against a 6-mm-diameter 440 C stainless-steel bearing ball. All experiments were conducted with loads of 0.49 to 3.6 N (average Hertzian contact pressure, 0.33 to 0.69 GPa), at a constant rotating speed of 120 rpm (sliding velocity ranging from 31 to 107 mm/s due to the range of wear track radii involved in the experiments), in a vacuum of 7 x 10 exp -7 Pa and at room temperature. The results indicate that there are similarities in friction behavior of MoS(x) films overs their life cycles regardless of load applied. The coefficient of friction (mu) decreases as load W increases according to mu = kW exp -1/3. The endurance life E of MoS(x) films decreases as the load W increases according to E = KW exp -1.4 for the load range. The load- (or contract-pressure-) dependent endurance life allows us to reduce the time for wear experiments and to accelerate endurance life testing of MoS(x) films. For the magnetron-sputtered MoS(x) films deposited on 440 C stainless-steel disks: the specific wear rate normalized to the load and the number of revolutions was 3 x 10 exp -8 mm exp 3/N-revolution; the specific wear rate normalized to the load and the total sliding distance was 8 x 10 exp -7 mm exp 3/N-m; and the nondimensional wear coefficient of was approximately 5 x 10 exp -6. The values are almost independent of load in the range 0.49 to 3.6 N (average Hertzian contact

  7. A 928 sq m (10000 sq ft) solar array

    NASA Technical Reports Server (NTRS)

    Lindberg, D. E.

    1972-01-01

    As the power requirements for space vehicles increases, the area of solar arrays that convert solar energy to usable electrical power increases. The requirements for a 928 sq m (10,000 sq ft) array, its design, and a full-scale demonstration of one quadrant (232 sq m (2500 sq ft)) deployed in a one-g field are described.

  8. 2-Methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ0814061), a novel microtubule inhibitor, evokes G2/M cell cycle arrest and apoptosis in human breast cancer cells.

    PubMed

    Xu, Jingwen; Zuo, Daiying; Qi, Huan; Shen, Qirong; Bai, Zhaoshi; Han, Mengting; Li, Zengqiang; Zhang, Weige; Wu, Yingliang

    2016-03-01

    Breast cancer is the leading cause of cancer death in women worldwide, and novel chemotherapeutic drugs with high activity and no drug resistance for treating breast cancer are needed urgently. In this study, we investigated the antitumor effect of 2-methoxy-5((3,4,5-trimethosyphenyl)seleninyl) phenol (SQ0814061), which has a strong inhibition of cell growth in MCF-7 and MDA-MB-231 cells. We demonstrated that SQ0814061 (SQ) time-dependently induced cell cycle arrest at G2/M phase and subsequently progressed into apoptosis, which is associated with microtubule depolymerization. Western blot analysis revealed that up-regulation of cyclin B1 and Aurora A was related with G2/M phase arrest in MCF-7 and MDA-MB-231 cells treatment with SQ. However, the formation of multinucleated cells after a long time exposed to SQ of MCF-7 cells delayed the cell death. In addition, apoptosis induced by SQ is correlated with the down-regulation of the PI3K-Akt-MDM2 pathway in MCF-7 and MDA-MB-231 cells. Treatment with the PI3K specific inhibitor, LY294002, increased SQ-induced cell growth inhibitory rate and apoptosis rate of MCF-7 and MDA-MB-231 cells. Moreover, SQ induced MCF-7 and MDA-MB-231 cells to generate reactive oxygen species (ROS), and the SQ-induced cell death was ROS dependent. In conclusion, all the data demonstrated that SQ exhibited its antitumor activity through disrupting the microtubule assembly, inducing cell cycle arrest and eventually apoptosis which is associated with PI3K-Akt-MDM2 pathway in MCF-7 and MDA-MB-231 cells. Therefore, the novel compound SQ is a promising microtubule inhibitor that has tremendous potentials for therapeutic treatment of human mastocarcinoma.

  9. 4H-SiC UV Photo Detector with Large Area and Very High Specific Detectivity

    NASA Technical Reports Server (NTRS)

    Yan, Feng; Shahid, Aslam; Franz, David; Xin, Xiaobin; Zhao, Jian H.; Zhao, Yuegang; Winer, Maurice

    2004-01-01

    Pt/4H-SiC Schottky photodiodes have been fabricated with the device areas up to 1 sq cm. The I-V characteristics and photo-response spectra have been measured and analyzed. For a 5 mm x 5 mm area device leakage current of 1 x 10(exp 15)A at zero bias and 1.2 x 10(exp 14)A at -IV have been established. The quantum efficiency is over 30% from 240nm to 320nm. The specific detectivity, D(sup *), has been calculated from the directly measured leakage current and quantum efficiency data and are shown to be higher than 10(exp 15) cmHz(sup 1/2)/W from 210nm to 350nm with a peak D(sup *) of 3.6 x 10(exp 15)cmH(sup 1/2)/W at 300nm.

  10. An Instrument to Measure Elemental Energy Spectra of Cosmic Ray Nuclei Up to 10(exp 16) eV

    NASA Technical Reports Server (NTRS)

    Adams, J.; Bashindzhagyan, G.; Chilingarian, A.; Drury, L.; Egorov, N.; Golubkov,S.; Korotkova, N.; Panasyuk, M.; Podorozhnyi, D.; Procqureur, J.

    2000-01-01

    A longstanding goal of cosmic ray research is to measure the elemental energy spectra of cosmic rays up to and through the "knee" (approx. equal to 3 x 10 (exp 15) eV. It is not currently feasible to achieve this goal with an ionization calorimeter because the mass required to be deployed in Earth orbit is very large (at least 50 tonnes). An alternative method will be presented. This is based on measuring the primary particle energy by determining the angular distribution of secondaries produced in a target layer using silicon microstrip detector technology. The proposed technique can be used over a wide range of energies (10 (exp 11)- 10 (exp 16) eV) and gives an energy resolution of 60% or better. Based on this technique, a design for a new lightweight instrument with a large aperture (KLEM) will be described.

  11. A direct gravitational lensing test for 10 exp 6 solar masses black holes in halos of galaxies

    NASA Technical Reports Server (NTRS)

    Wambsganss, Joachim; Paczynski, Bohdan

    1992-01-01

    We propose a method that will be able to detect or exclude the existence of 10 exp 6 solar masses black holes in the halos of galaxies. VLBA radio maps of two milliarcsecond jets of a gravitationally lensed quasar will show the signature of these black holes - if they exist. If there are no compact objects in this mass range along the line of sight, the two jets should be linear mappings of each other. If they are not, there must be compact objects of about 10 exp 6 solar masses in the halo of the galaxy that deform the images by gravitational deflection. We present numerical simulations for the two jets A and B of the double quasar 0957 + 561, but the method is valid for any gravitationally lensed quasar with structure on milliarcsecond scales. As a by-product from high-quality VLBA maps of jets A and B, one will be able to tell which features in the maps are intrinsic in the original jet and which are only an optical illusion, i.e., gravitational distortions by black holes along the line of sight.

  12. Friction, Wear, and Evaporation Rates of Various Materials in Vacuum to 10(exp -7) mm Hg

    NASA Technical Reports Server (NTRS)

    Buckley, Donald H.; Swikert, Max; Johnson, Robert L.

    1961-01-01

    The requirements for bearings and seals to operate in the environment of space dictate a new area for lubrication research. The low ambient pressures encountered in space can be expected to influence the behavior of oil, grease, and solid-film lubricants. The property of these materials most significantly affected by low ambient pressures is the evaporation rate. Various investigators have therefore measured the evaporation rates of oils and greases in vacuum as one method of establishing their relative merit for space applications (1-3). The results of this work have given some indication as to the oils and greases with the greatest stability at reduced ambient pressures. Only limited experimental work, however, has been reported in the literature for inorganic solids and soft metals which have potential use as solid lubricant films or coatings for hard alloy substrates [e.g. Reference ( 4 )]. In general, the evaporation rates of these materials would be lower than those of oils and greases. These films might therefore be very attractive as lubricants for high vacuum service.

  13. Heat Transfer and Boundary-Layer Transition on a Highly Polished Hemisphere-Cone in Free Flight at Mach Numbers Up to 3.14 and Reynolds Numbers Up to 24 x 10(exp 6)

    NASA Technical Reports Server (NTRS)

    Buglia, James J.

    1961-01-01

    A highly polished hemisphere-cone having a ratio of nose radius to base radius of 0.74 and a half-angle of 14.5 was flight tested at Mach numbers up to 4.70. Temperature and pressure data were obtained at Mach numbers up to 3.14 and a free-stream Reynolds number of 24 x 10(exp 6) based on body diameter. The nose of the model had a surface roughness of 2 to 5 microinches as measured with an interferometer. The measured Stanton numbers were in good agreement with theory. Transition Reynolds numbers based on the laminar boundary-layer momentum thickness at transition ranged from 2,190 to 794. Comparison with results from previous tests of blunt shapes having a surface roughness of 20 to 40 microinches showed that the high degree of polish was instrumental in delaying the transition from laminar to turbulent flow.

  14. SQ109, a New Drug Lead for Chagas Disease

    PubMed Central

    Veiga-Santos, Phercyles; Li, Kai; Lameira, Lilianne; de Carvalho, Tecia Maria Ulisses; Huang, Guozhong; Galizzi, Melina; Shang, Na; Li, Qian; Gonzalez-Pacanowska, Dolores; Hernandez-Rodriguez, Vanessa; Benaim, Gustavo; Guo, Rey-Ting; Urbina, Julio A.; Docampo, Roberto; de Souza, Wanderley

    2015-01-01

    We tested the antituberculosis drug SQ109, which is currently in advanced clinical trials for the treatment of drug-susceptible and drug-resistant tuberculosis, for its in vitro activity against the trypanosomatid parasite Trypanosoma cruzi, the causative agent of Chagas disease. SQ109 was found to be a potent inhibitor of the trypomastigote form of the parasite, with a 50% inhibitory concentration (IC50) for cell killing of 50 ± 8 nM, but it had little effect (50% effective concentration [EC50], ∼80 μM) in a red blood cell hemolysis assay. It also inhibited extracellular epimastigotes (IC50, 4.6 ± 1 μM) and the clinically relevant intracellular amastigotes (IC50, ∼0.5 to 1 μM), with a selectivity index of ∼10 to 20. SQ109 caused major ultrastructural changes in all three life cycle forms, as observed by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It rapidly collapsed the inner mitochondrial membrane potential (Δψm) in succinate-energized mitochondria, acting in the same manner as the uncoupler FCCP [carbonyl cyanide 4-(trifluoromethoxy)phenylhydrazone], and it caused the alkalinization of internal acidic compartments, effects that are likely to make major contributions to its mechanism of action. The compound also had activity against squalene synthase, binding to its active site; it inhibited sterol side-chain reduction and, in the amastigote assay, acted synergistically with the antifungal drug posaconazole, with a fractional inhibitory concentration index (FICI) of 0.48, but these effects are unlikely to account for the rapid effects seen on cell morphology and cell killing. SQ109 thus most likely acts, at least in part, by collapsing Δψ/ΔpH, one of the major mechanisms demonstrated previously for its action against Mycobacterium tuberculosis. Overall, the results suggest that SQ109, which is currently in advanced clinical trials for the treatment of drug-susceptible and drug

  15. Chemical reaction of atomic oxygen with evaporated films of copper, part 4

    NASA Technical Reports Server (NTRS)

    Fromhold, A. T.; Williams, J. R.

    1990-01-01

    Evaporated copper films were exposed to an atomic oxygen flux of 1.4 x 10(exp 17) atoms/sq cm per sec at temperatures in the range 285 to 375 F (140 to 191 C) for time intervals between 2 and 50 minutes. Rutherford backscattering spectroscopy (RBS) was used to determine the thickness of the oxide layers formed and the ratio of the number of copper to oxygen atoms in the layers. Oxide film thicknesses ranged from 50 to 3000 A (0.005 to 0.3 microns, or equivalently, 5 x 10(exp -9) to 3 x 10(exp -7); it was determined that the primary oxide phase was Cu2O. The growth law was found to be parabolic (L(t) varies as t(exp 1/2)), in which the oxide thickness L(t) increases as the square root of the exposure time t. The analysis of the data is consistent with either of the two parabolic growth laws. (The thin-film parabolic growth law is based on the assumption that the process is diffusion controlled, with the space charge within the growing oxide layer being negligible. The thick-film parabolic growth law is also based on a diffusion controlled process, but space-charge neutrality prevails locally within very thick oxides.) In the absence of a voltage measurement across the growing oxide, a distinction between the two mechanisms cannot be made, nor can growth by the diffusion of neutral atomic oxygen be entirely ruled out. The activation energy for the reaction is on the order of 1.1 eV (1.76 x 10(exp -19) joule, or equivalently, 25.3 kcal/mole).

  16. The Study of the Geomagnetic Variation for Sq current System

    NASA Astrophysics Data System (ADS)

    Zhao, X.; Du, A.

    2012-04-01

    The solar quiet variation (Sq) with a period of 24 hrs is a typical one of the quiet variations. Sq is generally caused by atmospheric tide-dynamo in ionosphere and it is controlled by the electric field, electric conductivity in ionosphere and neutral wind in middle-high altitude atmosphere. In our work, the geomagnetic field data observed by 90 ground-based observatories is used to analyze the local time variation of Sq. Sq is derived from five quiet-day geomagnetic data in every month by the FFT method. According to the pattern of geomagnetic X component in Sq, there is a prenoon-postnoon (before noon and after noon) asymmetry. This asymmetry is obvious in spring, summer and winter. The X component at 12:00-13:00 LT is about 5 nT larger than it at 11:00-12:00 LT. The ratio between the X component of daily variable amplitude and Y component of daily variable amplitude in middle and low (high) latitude regions in summer is greater (smaller) than that in winter. Used the sphere harmonic analysis method, the Sq equivalent current system is obtained. From the pattern of Sq current system, the prenoon-postnoon asymmetry may be caused by the electric field in the high latitude region. This electric field has two effects: the one is that the electric field from high latitude maps to the low latitude region; the other is this electric field penetrate to the middle latitude region directly. The combined action of these two effects makes the prenoon-postnoon asymmetry of Sq. The asymmetry also has an obvious seasonal effect. It may relate to the polar Sq and DP2 in the high latitude region.

  17. A 2.2 sq m /24 sq ft/ self-controlled deployable heat pipe radiator - Design and test

    NASA Technical Reports Server (NTRS)

    Edelstein, F.

    1975-01-01

    An all heat pipe, deployable radiator has been developed which can effectively control pumped fluid loop temperatures under varying loads using variable conductance panel heat pipes. The 2.2 sq m (24 sq ft) aluminum panel can be coupled to either a fluid header or a flexible heat pipe header capable of transporting 850 watts in a 90-deg bent configuration. Test results support the feasibility of using this system to passively control Freon-21 loop temperatures.

  18. Study of Bulk and Elementary Screw Dislocation Assisted Reverse Breakdown in Low-Voltage (less than 250 V) 4H-SiC p(+)n Junction diodes. Part 1; DC Properties

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Huang, Wei; Dudley, Michael

    1998-01-01

    Given the high density (approx. 10(exp 4)/sq cm) of elementary screw dislocations (Burgers vector = 1c with no hollow core) in commercial SiC wafers and epilayers, all appreciable current (greater than 1 A) SiC power devices will likely contain elementary screw dislocations for the foreseeable future. It is therefore important to ascertain the electrical impact of these defects, particularly in high-field vertical power device topologies where SiC is expected to enable large performance improvements in solid-state high-power systems. This paper compares the DC-measured reverse-breakdown characteristics of low-voltage (less than 250 V) small-area (less than 5 x 10(exp -4)/sq cm) 4H-SiC p(+)n diodes with and without elementary screw dislocations. Compared to screw dislocation-free devices, diodes containing elementary screw dislocations exhibited higher pre-breakdown reverse leakage currents, softer reverse breakdown I-V knees, and highly localized microplasmic breakdown current filaments. The observed localized 4H-SiC breakdown parallels microplasmic breakdowns observed in silicon and other semiconductors, in which space-charge effects limit current conduction through the local microplasma as reverse bias is increased.

  19. Study of Bulk and Elementary Screw Dislocation Assisted Reverse Breakdown in Low-Voltage (<250 V) 4H-SiC p+n Junction Diodes - Part 1: DC Properties

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Huang, Wei; Dudley, Michael

    1999-01-01

    Given the high density (approx. 10(exp 4)/sq cm) of elementary screw dislocations (Burgers vector = lc with no hollow core) in commercial SiC wafers and epilayers, all appreciable current (greater than 1 A) SiC power devices will likely contain elementary screw dislocations for the foreseeable future. It is therefore important to ascertain the electrical impact of these defects, particularly in high-field vertical power device topologies where SiC is expected to enable large performance improvements in solid-state high-power systems. This paper compares the DC-measured reverse-breakdown characteristics of low-voltage (less than 250 V) small-area (less than 5 x 10(exp -4) sq cm) 4H-SiC p(+)n diodes with and without elementary screw dislocations. Compared to screw dislocation-free devices, diodes containing elementary screw dislocations exhibited higher pre-breakdown reverse leakage currents, softer reverse breakdown I-V knees, and highly localized microplasmic breakdown current filaments. The observed localized 4H-SiC breakdown parallels microplasmic breakdowns observed in silicon and other semiconductors, in which space-charge effects limit current conduction through the local microplasma as reverse bias is increased.

  20. Preliminary Investigation of Molybdenum Disulfide-air-mist Lubrication for Roller Bearings Operating to DN Values of 1 x 10(exp 6) and Ball Bearings Operating to Temperatures of 1000 F

    NASA Technical Reports Server (NTRS)

    Macks, E F; Nemeth, Z N; Anderson, W J

    1951-01-01

    The effectiveness of molybdenum disulfide MoS2 as a bearing lubricant was determined at high temperature and at high speeds. A 1-inch-bore ball bearing operated at temperatures to 1000 F, a speed of 1725 rpm, and a thrust load of 20 pounds when lubricated only with MoS2-air mist. A 75-millimeter-bore cageless roller bearing, provided with a MoS2-syrup coating before operation, operated at DN values to 1 x 10(exp 6) with a load of 368 pounds.

  1. Contributions from the data samples in NOC technique on the extracting of the Sq variation

    NASA Astrophysics Data System (ADS)

    Wu, Yingyan; Xu, Wenyao

    2015-04-01

    The solar quiet daily variation, Sq, a rather regular variation is usually observed at mid-low latitudes on magnetic quiet days or less-disturbed days. It is mainly resulted from the dynamo currents in the ionospheric E region, which are driven by the atmospheric tidal wind and different processes and flow as two current whorls in each of the northern and southern hemispheres[1]. The Sq exhibits a conspicuous day-to-day (DTD) variability in daily range (or strength), shape (or phase) and its current focus. This variability is mainly attributed to changes in the ionospheric conductivity and tidal winds, varying with solar radiation and ionospheric conditions. Furthermore, it presents a seasonal variation and solar cycle variation[2-4]. In generally, Sq is expressed with the average value of the five international magnetic quiet days. Using data from global magnetic stations, equivalent current system of daily variation can be constructed to reveal characteristics of the currents[5]. In addition, using the differences of H component at two stations on north and south side of the Sq currents of focus, Sq is extracted much better[6]. Recently, the method of Natural Orthoganal Components (NOC) is used to decompose the magnetic daily variation and express it as the summation of eigenmodes, and indicate the first NOC eigenmode as the solar quiet daily variation, the second as the disturbance daily variation[7-9]. As we know, the NOC technique can help reveal simpler patterns within a complex set of variables, without designed basic-functions such as FFT technique. But the physical explanation of the NOC eigenmodes is greatly depends on the number of data samples and data regular-quality. Using the NOC method, we focus our present study on the analysis of the hourly means of the H component at BMT observatory in China from 2001 to 2008. The contributions of the number and the regular-quality of the data samples on which eigenmode corresponds to the Sq are analyzed, by

  2. Evolution of Iron K Alpha Line Emission in the Black Hole Candidate GX 339-4

    NASA Technical Reports Server (NTRS)

    Feng, Y. X.; Zhang, S. N.; Sun, X.; Durouchoux, Ph.; Chen, Wan; Cui, Wei

    2001-01-01

    GX 339-4 was regularly monitored with the Rossi X-Ray Timing Explorer during a period (in 1999) when its X-ray flux decreased significantly (from 4.26 x 10(exp -10) to 7.6 x 10(exp -12) ergs in the 3-20 keV band), as the source settled into the 'off state.' Our spectral analysis revealed the presence of a prominent iron K alpha line in the observed spectrum of the source for all observations. The line shows an interesting evolution: it is centered at approx. 6.4 keV when the measured flux is above 5 x 10(exp -1) ergs per sq cm/s but is shifted to approx. 6.7 keV at lower fluxes. The equivalent width of the line appears to increase significantly toward lower fluxes, although it is likely to be sensitive to calibration uncertainties. While the fluorescent emission of neutral or mildly ionized iron atoms in the accretion disk can perhaps account for the 6.4 keV line, as is often invoked for black hole candidates, it seems difficult to understand the 6.7 keV line with this mechanism because the disk should be less ionized at lower fluxes (unless its density changes drastically). On the other hand, the 6.7 keV line might be due to a recombination cascade of hydrogen- or helium-like iron ions in an optically thin, highly ionized plasma. We discuss the results in the context of proposed accretion models.

  3. Approaches to 100 Gbit/sq. in. recording density

    NASA Technical Reports Server (NTRS)

    Kryder, Mark H.

    1994-01-01

    A recording density of 10 Gbit/sq. in. is being pursued by a number of companies and universities in the National Storage Industry Consortium. It is widely accepted that this goal will be achieved in the laboratory within a few years. In this paper approaches to achieving 100 Gbit/sq. in. storage densities are considered. A major obstacle to continued scaling of magnetic recording to higher densities is that as the bit size is reduced, the grain size in the magnetic media must be reduced in order that media noise does not become so large that the signal to noise ratio (SNR) degrades sufficiently to make detection impossible. At 100 Gbit/sq. in., the bit size is only 0.006 square micrometers, which, in order to achieve 30 dB SNR, requires a grain size of about 2.5 nm. Such small grains are subject to thermal instability, and the recorded information will degrade over time unless the magnetic anisotropy of the materials used is increased significantly, or the media thickness is made much larger than expected on the basis of scaling today's longitudinal media thickness.

  4. Realtime Implementation of the APC/SQ and LPC-10 Speech Coding Algorithms.

    DTIC Science & Technology

    1982-06-01

    KEY WORDS (Continue on reverse side if necessary ad Identify by block number) Speech coding, APC/SQ, LPC-IO, 9.6 kb/s speech transmission, 2.4 kb/s...coding, digital voice terminal, real-time speech coder, \\ array processor 0. ABSTRACT (Continue on reverse side If neceeemy end Identify by block... machine , the CSPU. The control strategy for allowing each module as much flexibility as possible results in a structure that executes a module only if

  5. Initial Results from a Search for Lunar Radio Emission from Interactions of >= 10(exp 19) eV Neutrinos and Cosmic Rays

    NASA Technical Reports Server (NTRS)

    Gorham, P. W.; Liewer, K. M.; Naudet, C. J.

    2000-01-01

    Using the NASA Goldstone 70m antenna DSS 14 both singly and in coincidence with the 34 m antenna DSS 13 (21.7 km to the southeast), we have acquired approximately 12 hrs of livetime in a search for predicted pulsed radio emission from extremely-high energy cascades induced by neutrinos or cosmic rays in the lunar regolith. In about 4 hrs of single antenna observations, we reduced our sensitivity to impulsive terrestrial interference to a negligible level by use of a veto afforded by the unique capability of DSS 14. In the 8 hrs of dual-antenna observations, terrestrial interference is eliminated as a background. In both observing modes the thermal noise floor limits the sensitivity. We detected no events above statistical background. We report here initial limits based on these data which begin to constrain several predictions of the flux of EHE neutrinos.

  6. Long-term variation in the upper atmosphere as seen in the geomagnetic solar quiet (Sq) daily variation

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Yatagai, A. I.; Nose, M.; Hori, T.; Otsuka, Y.

    2012-12-01

    It has been well-known that geomagnetic solar quiet (Sq) daily variation is produced by the global ionospheric currents flowing in the E-region, which are generated by dynamo process via interaction between the neutral wind and ionospheric plasma in a region of the lower thermosphere and ionosphere. Then, to investigate the Sq amplitude is essential for understanding the long-term variations in the ionospheric conductivity and neutral wind of the lower thermosphere and ionosphere. Recently, Elias et al. [2010] reported that the Sq amplitude tends to increase by 5.4-9.9 % in the middle latitudes in a period of 1961-2001. They mentioned that the long-term variation of ionospheric conductivity associated with geomagnetic secular variation mainly determines the Sq trend, but that the rest component is due to ionospheric conductivity enhancement associated with cooling effect in the thermosphere due to increasing greenhouse gas. In the present study, we clarify the characteristics of the long-term variation in the Sq amplitude using the long-term observation data of geomagnetic field and neutral wind. In the present analysis, we used the F10.7 solar flux as a good indicator of the variation in the solar irradiance in the EUV and UV range as well as geomagnetic field data with time resolution of 1 hour observed at 184 geomagnetic stations. The definition of the Sq amplitude is the difference of the H-component between the maximum and minimum every day when the Kp index is less than 4. As a result, the long-term variation in the Sq amplitude at all the geomagnetic stations shows a strong correlation with the solar F10.7 flux which depends on 11-year solar activity. The relationship between the Sq amplitude and F10.7 flux was not linear but nonlinear. This nonlinearity could be interpreted as the decrease of production rate of electrons and ions in the ionosphere for the strong EUV and UV fluxes as already reported by Balan et al. [1993]. In order to minimize the solar

  7. Study of Bulk and Elementary Screw Dislocation Assisted Reverse Breakdown in Low-Voltage (< 250 V) 4H-SiC p(sup +)n Junction Diodes--Part II: Dynamic Breakdown Properties. Part 2; Dynamic Breakdown Properties

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Fazi, Christian

    1999-01-01

    This paper outlines the dynamic reverse-breakdown characteristics of low-voltage (<250 V) small-area <5 x 10(exp -4) sq cm 4H-SiC p(sup +)n diodes subjected to nonadiabatic breakdown-bias pulsewidths ranging from 0.1 to 20 microseconds. 4H-SiC diodes with and without elementary screw dislocations exhibited positive temperature coefficient of breakdown voltage and high junction failure power densities approximately five times larger than the average failure power density of reliable silicon pn rectifiers. This result indicates that highly reliable low-voltage SiC rectifiers may be attainable despite the presence of elementary screw dislocations. However, the impact of elementary screw dislocations on other more useful 4H-SiC power device structures, such as high-voltage (>1 kV) pn junction and Schottky rectifiers, and bipolar gain devices (thyristors, IGBT's, etc.) remains to be investigated.

  8. Comprehensive Quantitative Analysis of SQ Injection Using Multiple Chromatographic Technologies.

    PubMed

    Chau, Siu-Leung; Huang, Zhi-Bing; Song, Yan-Gang; Yue, Rui-Qi; Ho, Alan; Lin, Chao-Zhan; Huang, Wen-Hua; Han, Quan-Bin

    2016-08-19

    Quality control of Chinese medicine injections remains a challenge due to our poor knowledge of their complex chemical profile. This study aims to investigate the chemical composition of one of the best-selling injections, Shenqi Fuzheng (SQ) injection (SQI), via a full component quantitative analysis. A total of 15 representative small molecular components of SQI were simultaneously determined using ultra-high performance liquid chromatography (UHPLC) coupled with quadrupole tandem time-of-flight mass spectrometry (Q-TOF-MS); saccharide composition of SQI was also quantitatively determined by high performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) on an amino column before and after acid hydrolysis. The existence of polysaccharides was also examined on a gel permeation chromatography column. The method was well validated in terms of linearity, sensitivity, precision, accuracy and stability, and was successfully applied to analyze 13 SQI samples. The results demonstrate that up to 94.69% (w/w) of this injection product are quantitatively determined, in which small molecules and monosaccharide/sucrose account for 0.18%-0.21%, and 53.49%-58.2%, respectively. The quantitative information contributes to accumulating scientific evidence to better understand the therapy efficacy and safety of complex Chinese medicine injections.

  9. Inactivation and pharmacological properties of sqKv1A homotetramers in Xenopus oocytes cannot account for behavior of the squid "delayed rectifier" K(+) conductance.

    PubMed

    Jerng, Henry H; Gilly, William F

    2002-06-01

    Considerable published evidence suggests that alpha-subunits of the cloned channel sqKv1A compose the "delayed rectifier" in the squid giant axon system, but discrepancies regarding inactivation properties of cloned versus native channels exist. In this paper we define the mechanism of inactivation for sqKv1A channels in Xenopus oocytes to investigate these and other discrepancies. Inactivation of sqKv1A in Xenopus oocytes was found to be unaffected by genetic truncation of the N-terminus, but highly sensitive to certain amino acid substitutions around the external mouth of the pore. External TEA and K(+) ions slowed inactivation of sqKv1A channels in oocytes, and chloramine T (Chl-T) accelerated inactivation. These features are all consistent with a C-type inactivation mechanism as defined for Shaker B channels. Treatment of native channels in giant fiber lobe neurons with TEA or high K(+) does not slow inactivation, nor does Chl-T accelerate it. Pharmacological differences between the two channel types were also found for 4-aminopyridine (4AP). SqKv1A's affinity for 4AP was poor at rest and increased after activation, whereas 4AP block occurred much more readily at rest with native channels than when they were activated. These results suggest that important structural differences between sqKv1A homotetramers and native squid channels are likely to exist around the external and internal mouths of the pore.

  10. Statistical characteristics of the day-to-day variability in the geomagnetic Sq field

    NASA Astrophysics Data System (ADS)

    Chen, Gen-Xiong; Xu, Wen-Yao; Du, Ai-Min; Wu, Ying-Yan; Chen, Bo; Liu, Xiao-Can

    2007-06-01

    Day-to-day variability in the geomagnetic Sq field is studied by using the magnetic data from a meridian chain of magnetometers along 120°E longitude. The method of natural orthogonal components (NOC or eigenmode analysis) is applied to separate the Sq variation from complicated disturbances. The first eigenmode with the largest eigenvalue represents fairly well the Sq variation with a conspicuous day-to-day variability in the daily range. For the stations on the same north- or south-side of the Sq current system focus, the day-to-day variations show a positive correlation. In contrast, for the stations on the different sides of the Sq focus, they show a negative correlation, suggesting an important role of latitudinal shift of the Sq current system focus to the day-to-day variability in the Sq daily range. The Sq daily range is correlated with the magnetic indices Ap and Dst in a peculiar way: On some severe disturbed days, noticeable enhancements of the Sq are observed, implying increases in the ionospheric conductivities and/or tidal wind velocities; on other severe disturbed days, however, dramatically reduced Sq variations occur, suggesting dominant effects of the "disturbance dynamo" process.

  11. Improvement of critical current density in thallium-based (Tl,Bi)Sr(1.6)Ba(0.4)Ca2Cu3O(x) superconductors

    NASA Technical Reports Server (NTRS)

    Ren, Z. F.; Wang, C. A.; Wang, J. H.; Miller, D. J.; Goretta, K. C.

    1995-01-01

    Epitaxial (Tl,Bi)Sr(1.6)Ba(0.4)Ca2Cu3O(x) ((Tl,Bi)-1223) thin films on (100) single crystal LaAlO3 substrates were synthesized by a two-step procedure. Phase development, microstructure, and relationships between film and substrate were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Resistance versus temperature, zero-field-cooled and field cooled magnetization, and transport critical current density (J(sub c)) were measured. The zero-resistance temperature was 105-111 K. J(sub c) at 77 K and zero field was greater than 2 x 10(exp 6) A/sq cm. The films exhibited good flux pinning properties.

  12. Semi-annual Sq-variation in solar activity cycle

    NASA Astrophysics Data System (ADS)

    Pogrebnoy, V.; Malosiev, T.

    The peculiarities of semi-annual variation in solar activity cycle have been studied. The data from observatories having long observational series and located in different latitude zones were used. The following observatories were selected: Huancayo (magnetic equator), from 1922 to 1959; Apia (low latitudes), from 1912 to 1961; Moscow (middle latitudes), from 1947 to 1965. Based on the hourly values of H-components, the average monthly diurnal amplitudes (a difference between midday and midnight values), according to five international quiet days, were computed. Obtained results were compared with R (relative sunspot numbers) in the ranges of 0-30R, 40-100R, and 140-190R. It was shown, that the amplitude of semi-annual variation increases with R, from minimum to maximum values, on average by 45%. At equatorial Huancayo observatory, the semi-annual Sq(H)-variation appears especially clearly: its maximums take place at periods of equinoxes (March-April, September-October), and minimums -- at periods of solstices (June-July, December-January). At low (Apia observatory) and middle (Moscow observatory) latitudes, the character of semi-annual variation is somewhat different: it appears during the periods of equinoxes, but considerably less than at equator. Besides, with the growth of R, semi-annual variation appears against a background of annual variation, in the form of second peaks (maximum in June). At observatories located in low and middle latitudes, second peaks become more appreciable with an increase of R (March-April and September-October). During the periods of low solar activity, they are insignificant. This work has been carried out with the support from International Scientific and Technology Center (Project #KR-214).

  13. Absolute intensities and foreign gas broadening coefficients of the 11(sub 1,10) from 11(sub 2,10) and 18(sub 0,18) from 18(sub 1,18) lines in the nu(sub 7) band of C2H4

    NASA Technical Reports Server (NTRS)

    Reuter, Dennis C.; Sirota, J. Marcos

    1993-01-01

    Absolute intensities and foreign gas broadening coefficients of the 18(sub 0,18) from 18(sub 1,18) and 11(sub 1,10) from 11(sub 2,10) transitions in the nu(sub 7) band of C2H4 near 948/cm have been measured at a spectral resolution of approximately 5 x 10(exp -4)/cm using tunable diode laser spectrometry. Ar, He, N2, O2 were used as the broadening gases. In order to determine the temperature dependence of the broadening coefficient, data were obtained at temperatures ranging from 150 to 296 K. The absolute intensity of the 5(sub 0,5) from 5(sub 1,5) transition was also found at 296 K. A band strength of 330 +/- 10/sq cm/atm was obtained from weighted averages of the individual line intensities and a rigid asymmetric top calculation.

  14. A low noise 230 GHz heterodyne receiver employing .25 sq micron area Nb/AlO(x)/Nb tunnel junctions

    NASA Technical Reports Server (NTRS)

    Kooi, Jacob W.; Chan, M.; Phillips, T. G.; Bumble, B.; Leduc, H. G.

    1992-01-01

    Recent results for a full height rectangular waveguide mixer with an integrated IF matching network are reported. Two 0.25 sq micron Nb/AlO(x)/Nb superconducting insulating superconducting (SIS) tunnel junctions with a current density of about 8500 A/sq cm and omega RC of about 2.5 at 230 GHz have been tested. Detailed measurements of the receiver noise have been made from 200-290 GHz for both junctions at 4.2 K. The lowest receiver noise temperatures were recorded at 239 GHz, measuring 48 K DSB at 4.2 K and 40 K DSB at 2.1 K. The 230 GHz receiver incorporates a one octave wide integrated low pass filter and matching network which transforms the pumped IF junction impedance to 50 ohms over a wide range of impedances.

  15. Seasonal variation of the Sq focus position during 2006-2010

    NASA Astrophysics Data System (ADS)

    Vichare, Geeta; Rawat, Rahul; Jadhav, Madhavi; Sinha, Ashwini Kumar

    2017-01-01

    In the present paper, the perception of the seasonal variation of the Sq focus position is re-examined during low solar activity period (2006-2010). Equivalent current vectors are plotted for each geomagnetic quiet day (Ap ⩽ 5), using diurnal variations of H and D components measured at the magnetic observatories located in a narrow longitudinal belt of the Indo-Russian region. On the formation of well-defined Sq current loop, the information about the Sq focus is extracted by identifying a pair of neighboring stations with opposite zonal currents and nearby local times with opposite meridional currents. Thus, the method employed here is different from the methods used in earlier studies. Prominent seasonal variations in the Sq focus latitude, as well as in the local time of Sq focus, are observed. It is observed that the Sq focus is located at ∼30 deg in March equinox, but it moves to lower latitudes in the month of September. In winter, it shows large variability and also the formation of clear Sq current loop is less frequent. The local time of Sq focus is at ∼12 LT in March and shifts to ∼10 LT during September. It is clearly evident from the present analysis that the March and September equinoxes behave differently. The dominance of DE3 and semidiurnal waves in the September equinox could be the reason for the observed disparity.

  16. Characterization of FGFR1 Locus in sqNSCLC Reveals a Broad and Heterogeneous Amplicon.

    PubMed

    Rooney, Claire; Geh, Catherine; Williams, Victoria; Heuckmann, Johannes M; Menon, Roopika; Schneider, Petra; Al-Kadhimi, Katherine; Dymond, Michael; Smith, Neil R; Baker, Dawn; French, Tim; Smith, Paul D; Harrington, Elizabeth A; Barrett, J Carl; Kilgour, Elaine

    2016-01-01

    FGFR1 amplification occurs in ~20% of sqNSCLC and trials with FGFR inhibitors have selected FGFR1 amplified patients by FISH. Lung cancer cell lines were profiled for sensitivity to AZD4547, a potent, selective inhibitor of FGFRs 1-3. Sensitivity to FGFR inhibition was associated with but not wholly predicted by increased FGFR1 gene copy number. Additional biomarker assays evaluating expression of FGFRs and correlation between amplification and expression in clinical tissues are therefore warranted. We validated nanoString for mRNA expression analysis of 194 genes, including FGFRs, from clinical tumour tissue. In a panel of sqNSCLC tumours 14.4% (13/90) were FGFR1 amplified by FISH. Although mean FGFR1 expression was significantly higher in amplified samples, there was significant overlap in the range of expression levels between the amplified and non-amplified cohorts with several non-amplified samples expressing FGFR1 to levels equivalent to amplified samples. Statistical analysis revealed increased expression of FGFR1 neighboring genes on the 8p12 amplicon (BAG4, LSM1 and WHSC1L1) in FGFR1 amplified tumours, suggesting a broad rather than focal amplicon and raises the potential for codependencies. High resolution aCGH analysis of pre-clinical and clinical samples supported the presence of a broad and heterogeneous amplicon around the FGFR1 locus. In conclusion, the range of FGFR1 expression levels in both FGFR1 amplified and non-amplified NSCLC tissues, together with the breadth and intra-patient heterogeneity of the 8p amplicon highlights the need for gene expression analysis of clinical samples to inform the understanding of determinants of response to FGFR inhibitors. In this respect the nanoString platform provides an attractive option for RNA analysis of FFPE clinical samples.

  17. Entner–Doudoroff pathway for sulfoquinovose degradation in Pseudomonas putida SQ1

    PubMed Central

    Felux, Ann-Katrin; Spiteller, Dieter; Klebensberger, Janosch; Schleheck, David

    2015-01-01

    Sulfoquinovose (SQ; 6-deoxy-6-sulfoglucose) is the polar head group of the plant sulfolipid SQ-diacylglycerol, and SQ comprises a major proportion of the organosulfur in nature, where it is degraded by bacteria. A first degradation pathway for SQ has been demonstrated recently, a “sulfoglycolytic” pathway, in addition to the classical glycolytic (Embden–Meyerhof) pathway in Escherichia coli K-12; half of the carbon of SQ is abstracted as dihydroxyacetonephosphate (DHAP) and used for growth, whereas a C3-organosulfonate, 2,3-dihydroxypropane sulfonate (DHPS), is excreted. The environmental isolate Pseudomonas putida SQ1 is also able to use SQ for growth, and excretes a different C3-organosulfonate, 3-sulfolactate (SL). In this study, we revealed the catabolic pathway for SQ in P. putida SQ1 through differential proteomics and transcriptional analyses, by in vitro reconstitution of the complete pathway by five heterologously produced enzymes, and by identification of all four organosulfonate intermediates. The pathway follows a reaction sequence analogous to the Entner–Doudoroff pathway for glucose-6-phosphate: It involves an NAD+-dependent SQ dehydrogenase, 6-deoxy-6-sulfogluconolactone (SGL) lactonase, 6-deoxy-6-sulfogluconate (SG) dehydratase, and 2-keto-3,6-dideoxy-6-sulfogluconate (KDSG) aldolase. The aldolase reaction yields pyruvate, which supports growth of P. putida, and 3-sulfolactaldehyde (SLA), which is oxidized to SL by an NAD(P)+-dependent SLA dehydrogenase. All five enzymes are encoded in a single gene cluster that includes, for example, genes for transport and regulation. Homologous gene clusters were found in genomes of other P. putida strains, in other gamma-Proteobacteria, and in beta- and alpha-Proteobacteria, for example, in genomes of Enterobacteria, Vibrio, and Halomonas species, and in typical soil bacteria, such as Burkholderia, Herbaspirillum, and Rhizobium. PMID:26195800

  18. Entner-Doudoroff pathway for sulfoquinovose degradation in Pseudomonas putida SQ1.

    PubMed

    Felux, Ann-Katrin; Spiteller, Dieter; Klebensberger, Janosch; Schleheck, David

    2015-08-04

    Sulfoquinovose (SQ; 6-deoxy-6-sulfoglucose) is the polar head group of the plant sulfolipid SQ-diacylglycerol, and SQ comprises a major proportion of the organosulfur in nature, where it is degraded by bacteria. A first degradation pathway for SQ has been demonstrated recently, a "sulfoglycolytic" pathway, in addition to the classical glycolytic (Embden-Meyerhof) pathway in Escherichia coli K-12; half of the carbon of SQ is abstracted as dihydroxyacetonephosphate (DHAP) and used for growth, whereas a C3-organosulfonate, 2,3-dihydroxypropane sulfonate (DHPS), is excreted. The environmental isolate Pseudomonas putida SQ1 is also able to use SQ for growth, and excretes a different C3-organosulfonate, 3-sulfolactate (SL). In this study, we revealed the catabolic pathway for SQ in P. putida SQ1 through differential proteomics and transcriptional analyses, by in vitro reconstitution of the complete pathway by five heterologously produced enzymes, and by identification of all four organosulfonate intermediates. The pathway follows a reaction sequence analogous to the Entner-Doudoroff pathway for glucose-6-phosphate: It involves an NAD(+)-dependent SQ dehydrogenase, 6-deoxy-6-sulfogluconolactone (SGL) lactonase, 6-deoxy-6-sulfogluconate (SG) dehydratase, and 2-keto-3,6-dideoxy-6-sulfogluconate (KDSG) aldolase. The aldolase reaction yields pyruvate, which supports growth of P. putida, and 3-sulfolactaldehyde (SLA), which is oxidized to SL by an NAD(P)(+)-dependent SLA dehydrogenase. All five enzymes are encoded in a single gene cluster that includes, for example, genes for transport and regulation. Homologous gene clusters were found in genomes of other P. putida strains, in other gamma-Proteobacteria, and in beta- and alpha-Proteobacteria, for example, in genomes of Enterobacteria, Vibrio, and Halomonas species, and in typical soil bacteria, such as Burkholderia, Herbaspirillum, and Rhizobium.

  19. Are the equatorial electrojet and the Sq coupled systems? Transfer entropy approach

    NASA Astrophysics Data System (ADS)

    Vichare, Geeta; Bhaskar, Ankush; Ramesh, Durbha Sai

    2016-05-01

    Whether equatorial electrojet (EEJ) and solar quiet (Sq) are independent systems or not is a long standing question. Techniques such as correlation analysis, interpretation of the westward currents observed between EEJ and Sq focus, along with the simulation studies have been used to address this question, hitherto. In this article, we revisit this problem using a method based on transfer entropy that examines the relationship between day-to-day variability in EEJ and Sq during low solar activity period (year 2007-08). Magnetic field variations in the horizontal component from the geomagnetic observatory, Tirunelveli (TIR) from the Indian region are used as a proxy for EEJ currents. To represent variations of Sq current system, two stations outside the EEJ belt, Nagpur (NGP) and Jaipur (JAI) are analyzed. Our analyses clearly demonstrate that significant information is exchanged between EEJ and Sq variations, and hence they are in a cross-talk with each other, indicating EEJ and Sq are coupled systems. Variations of time scales less than 2 h appear at the equatorial station before Sq stations. Similar analyses carried out for the African sector also validate the above results.

  20. Synaptic activity bidirectionally regulates a novel sequence-specific S-Q phosphoproteome in neurons

    PubMed Central

    Siddoway, Benjamin; Hou, Hailong; Yang, Hongtian; Petralia, Ronald; Xia, Houhui

    2013-01-01

    Protein phosphorylation plays a critical role in neuronal transcription, translation, cell viability, and synaptic plasticity. In neurons, phospho-enzymes and specific substrates directly link glutamate release and post-synaptic depolarization to these cellular functions; however, many of these enzymes and their protein substrates remain uncharacterized or unidentified. In this article, we identify a novel, synaptically-driven neuronal phosphoproteome characterized by a specific motif of serine/threonine-glutamine ([S/T]-Q, abbreviated as SQ). These SQ-containing substrates are predominantly localized to dendrites, synapses, the soma; and activation of this SQ phosphoproteome by bicuculline application is induced via calcium influx through L-type calcium channels. On the other hand, acute application of NMDA can inactivate this SQ phosphoproteome. We demonstrate that the SQ motif kinase Ataxia-telangiectasia mutated (ATM) can also localize to dendrites and dendritic spines, in addition to other subcellular compartments, and is activated by bicuculline application. Pharmacology studies indicate that ATM and its sister kinase ATR up-regulate these neuronal SQ substrates. Phosphoproteomics identified over 150 SQ-containing substrates whose phosphorylation is bidirectionally-regulated by synaptic activity. PMID:24117848

  1. Sq solar variation at Medea Observatory (Algeria), from 2008 to 2011

    NASA Astrophysics Data System (ADS)

    Anad, F.; Amory-Mazaudier, C.; Hamoudi, M.; Bourouis, S.; Abtout, A.; Yizengaw, E.

    2016-11-01

    This paper presents the regular variations of terrestrial magnetic field recorded by a new magnetic Observatory Medea, Algeria (geographic latitude: 36.85°N, geographic longitude: 2.93°E, geomagnetic latitude: 27.98°N, geomagnetic longitude: 77.7°E) during 2008-2011. The diurnal and seasonal variations of the solar quiet (Sq) variations are analyzed. The results show differences in the diurnal pattern of the northward-component Sq variation (SqX) at different seasons. The seasonal variation of SqX is similar in different years. The diurnal pattern of SqX from July through September cannot be explained by an equivalent current system that is symmetric about the noon time sector. The observations indicate that the major axis of the elliptic current system is tilted towards the equator in the morning hours during those months. The diurnal pattern of SqY indicates southward currents in the morning and northward currents in the afternoon, except during February-March 2009 when there is apparently no southward current during the morning. For the other months, the observations indicate that the maximum northward current intensity in the afternoon tends to be greater than the maximum southward current intensity in the morning. This is because of the UT variation of the Sq current system. That is, the pattern and strength of the Sq current system are different when SqY is measured in the morning around 8 UT and in the afternoon around 14 UT. The amplitude of these extreme varies linearly with the solar cycle. For the SqY component, the changes in the morning maximum have an annual variation while that of the afternoon minimum has a semi-annual variation. These variations are attributed to seasonal variations in the ionospheric E-region conductivity and atmospheric tidal winds. The field-aligned currents can also contribute to the seasonal variation of SqY. However, the two-dimensional approach used in this article does not allow us to quantitatively determine their

  2. A 58 sq m Passive Resonant Ring Laser Gyroscope

    NASA Astrophysics Data System (ADS)

    Shaw, G. L.; Simmons, B. J.

    1984-01-01

    A 7.62 x 7.62 m Passive Ring Resonator Laser Gyro (PRRLG) is analyzed. Each element of the PRRLG is consistent with the requirements for geophysical applications, which would include precision measurements of earth rotation and polar wobble. The shot noise limit was calculated to be about 3 x 10 to the -8th ERU (tau = 1 sec), and, with a predicted transition Fourier frequency between white noise and 1/f noise at about 200 microHz, a resolution on the order of about 4 x 10 to the -10th ERU is feasible.

  3. Relationship between the equatorial electrojet and global Sq currents at the dip equator region

    NASA Astrophysics Data System (ADS)

    Hamid, Nurul Shazana Abdul; Liu, Huixin; Uozumi, Teiji; Yumoto, Kiyohumi; Veenadhari, Bhaskara; Yoshikawa, Akimasa; Sanchez, Jairo Avendaño

    2014-12-01

    The equatorial electrojet (EEJ) is a strong eastward ionospheric current flowing in a narrow band along the dip equator. In this study, we examined the EEJ-Sq relationship by using observations at six stations in the South American, Indian, and Southeast Asian sectors. The analysis was carried out with data on geomagnetically quiet days with Kp ≤3 from 2005 to 2011. A normalization approach was used because it yields more accurate results by overcoming the uncertainties due to latitudinal variation of the EEJ and Sq. A weak positive correlation between the EEJ and Sq was obtained in the Southeast Asian sector, while weak negative correlations were obtained in the South American and Indian sectors. EEJ-Sq relationship is found to be independent of the hemispheric configuration of stations used to calculate their magnetic perturbations, and it also only changed slightly during low and moderate solar activity levels. These results demonstrate that the Southeast Asian sector is indeed different from the Indian and South American sectors, which is indicative of unique physical processes particularly related to the electro-dynamo. Furthermore, we also demonstrate that the definition of the EEJ, that is, the total current or enhanced current, can significantly affect the conclusions drawn from EEJ-Sq correlations.

  4. Possible Detection of an Emission Cyclotron Resonance Scattering Feature from the Accretion-Powered Pulsar 4U 1626-67

    NASA Technical Reports Server (NTRS)

    Iwakiri, W. B.; Terada, Y.; Tashiro, M. S.; Mihara, T.; Angelini, L.; Yamada, S.; Enoto, T.; Makishima, K.; Nakajima, M.; Yoshida, A.

    2012-01-01

    We present analysis of 4U 1626-67, a 7.7 s pulsar in a low-mass X-ray binary system, observed with the hard X-ray detector of the Japanese X-ray satellite Suzaku in 2006 March for a net exposure of 88 ks. The source was detected at an average 10-60 keY flux of approx 4 x 10-10 erg / sq cm/ s. The phase-averaged spectrum is reproduced well by combining a negative and positive power-law times exponential cutoff (NPEX) model modified at approx 37 keY by a cyclotron resonance scattering feature (CRSF). The phase-resolved analysis shows that the spectra at the bright phases are well fit by the NPEX with CRSF model. On the other hand. the spectrum in the dim phase lacks the NPEX high-energy cutoff component, and the CRSF can be reproduced by either an emission or an absorption profile. When fitting the dim phase spectrum with the NPEX plus Gaussian model. we find that the feature is better described in terms of an emission rather than an absorption profile. The statistical significance of this result, evaluated by means of an F test, is between 2.91 x 10(exp -3) and 1.53 x 10(exp -5), taking into account the systematic errors in the background evaluation of HXD-PIN. We find that the emission profile is more feasible than the absorption one for comparing the physical parameters in other phases. Therefore, we have possibly detected an emission line at the cyclotron resonance energy in the dim phase.

  5. Sounding Rocket Experiments to Investigate Thermal Electron Heating in the Sq Current Focus

    NASA Astrophysics Data System (ADS)

    Abe, T.; Ishisaka, K.; Kumamoto, A.; Yoshikawa, A.; Takahashi, T.; Tanaka, M.

    2015-12-01

    Sounding rocket observations in the southern part of Japan suggest that the electron temperature profile occasionally exhibits the local increase by several hundred K at 100-110 km altitudes at 1100-1200 LT in winter. Detailed study of the temperature profiles indicates that such an increase is closely related to the existence of Sq current focus, because it becomes more significant when the measurement is made near the center of Sq focus. In order to understand a general feature of this unusual phenomena occurring in the Sq current focus, the sounding rocket experiment was conducted in Uchinoura of Japan. In this experiment, we launched "S-310-37" rocket equipped with a total of eight science instruments at 11:20 JST on January 16, 2007 after being convinced that the Sq current was approaching to the planned rocket trajectory. The geomagnetic activity had been successively quiet on that day so that we can estimate the position of Sq current focus. Our analysis of the obtained data indicates that the electron temperature was certainly increased by about 500-600 K at the altitude of 97-101 km with respect to the background. Strong electron density perturbation was also observed to exist above 97 km altitude, which corresponds to the lower boundary of the high electron temperatures. It is also noticeable that both the electric field and magnetic field data include unusual variation in the same altitude region as the temperature increase was observed, suggesting a possible connection between the thermal electron heating and variation of the electric and/or magnetic field. Thus, the first experiment in 2007 revealed a general feature of such unusual phenomena in the Sq current focus, and thereby our interest to the generation mechanism for increasing the electron temperature was more and more increased. We will conduct the second rocket experiment to investigate such unusual phenomena in the Sq current focus in January 2016. In this experiment, we will try to measure

  6. The ACE inhibitor ( sup 3 H)SQ29,852 identifies a high affinity recognition site located in the human temporal cortex

    SciTech Connect

    Barnes, N.M.; Costall, B.; Egli, P.; Horovitz, Z.P.; Ironside, J.W.; Naylor, R.J.; Williams, T.J. )

    1990-07-01

    The angiotensin converting enzyme (ACE) inhibitor ({sup 3}H)SQ29,852 identified a single high affinity recognition site (defined by 10.0 microM captopril) in the human temporal cortex (pKD 8.62 +/- 0.03; Bmax 248 +/- 24 fmol mg-1 protein, mean +/- S.E.M., n = 4). ACE inhibitors and thiorphan competed to a similar level for the ({sup 3}H)SQ29,852 binding site in the human temporal cortex with a rank order of affinity (pKi values mean +/- S.E.M., n = 3), lisinopril (9.49 +/- 0.02), captopril (9.16 +/- 0.08), SQ29,852 (8.58 +/- 0.04), epicaptopril (7.09 +/- 0.08), fosinopril (7.08 +/- 0.05) and thiorphan (6.40 +/- 0.04). Since this rank order of affinity is similar to the affinity of these compounds to inhibit brain ACE activity it is concluded that ({sup 3}H)SQ29,852 selectively labels the inhibitor recognition site of ACE in the human temporal cortex.

  7. Antitubercular Nanocarrier Combination Therapy: Formulation Strategies and in Vitro Efficacy for Rifampicin and SQ641.

    PubMed

    D'Addio, Suzanne M; Reddy, Venkata M; Liu, Ying; Sinko, Patrick J; Einck, Leo; Prud'homme, Robert K

    2015-05-04

    Tuberculosis (TB) remains a major global health concern, and new therapies are needed to overcome the problems associated with dosing frequency, patient compliance, and drug resistance. To reduce side effects associated with systemic drug distribution and improve drug concentration at the target site, stable therapeutic nanocarriers (NCs) were prepared and evaluated for efficacy in vitro in Mycobacterium tuberculosis-infected macrophages. Rifampicin (RIF), a current, broad-spectrum antibiotic used in TB therapy, was conjugated by degradable ester bonds to form hydrophobic prodrugs. NCs encapsulating various ratios of nonconjugated RIF and the prodrugs showed the potential ability to rapidly deliver and knockdown intracellular M. tuberculosis by nonconjugated RIF and to obtain sustained release of RIF by hydrolysis of the RIF prodrug. NCs of the novel antibiotic SQ641 and a combination NC with cyclosporine A were formed by flash nanoprecipitation. Delivery of SQ641 in NC form resulted in significantly improved activity compared to that of the free drug against intracellular M. tuberculosis. A NC formulation with a three-compound combination of SQ641, cyclosporine A, and vitamin E inhibited intracellular replication of M. tuberculosis significantly better than SQ641 alone or isoniazid, a current first-line anti-TB drug.

  8. Antitubercular Nanocarrier Combination Therapy: Formulation Strategies and in Vitro Efficacy for Rifampicin and SQ641

    PubMed Central

    2015-01-01

    Tuberculosis (TB) remains a major global health concern, and new therapies are needed to overcome the problems associated with dosing frequency, patient compliance, and drug resistance. To reduce side effects associated with systemic drug distribution and improve drug concentration at the target site, stable therapeutic nanocarriers (NCs) were prepared and evaluated for efficacy in vitro in Mycobacterium tuberculosis-infected macrophages. Rifampicin (RIF), a current, broad-spectrum antibiotic used in TB therapy, was conjugated by degradable ester bonds to form hydrophobic prodrugs. NCs encapsulating various ratios of nonconjugated RIF and the prodrugs showed the potential ability to rapidly deliver and knockdown intracellular M. tuberculosis by nonconjugated RIF and to obtain sustained release of RIF by hydrolysis of the RIF prodrug. NCs of the novel antibiotic SQ641 and a combination NC with cyclosporine A were formed by flash nanoprecipitation. Delivery of SQ641 in NC form resulted in significantly improved activity compared to that of the free drug against intracellular M. tuberculosis. A NC formulation with a three-compound combination of SQ641, cyclosporine A, and vitamin E inhibited intracellular replication of M. tuberculosis significantly better than SQ641 alone or isoniazid, a current first-line anti-TB drug. PMID:25811733

  9. SOAR versus SQ3R: A Test of Two Study Systems

    ERIC Educational Resources Information Center

    Jairam, Dharma; Kiewra, Kenneth A.; Rogers-Kasson, Sarah; Patterson-Hazley, Melissa; Marxhausen, Kim

    2014-01-01

    Although researchers have long investigated ways to improve study habits and raise achievement, few studies compare study strategy systems with one another. No study to date has compared the long popular SQ3R (Survey, Question, Read, Recite, Review) system with the more modern SOAR (Select, Organize, Associate, Regulate) system. This study…

  10. Clinical benefits of treatment with SQ house dust mite sublingual tablet in house dust mite allergic rhinitis.

    PubMed

    Andersen, Kristian Funding; Demoly, Pascal; Kleine-Tebbe, Jörg; Rehm, Dorte

    2017-03-08

    Treatment with SQ house dust mite sublingual tablet for 1 year resulted in a decreased probability of having an allergic rhinitis exacerbation day (from 11% (placebo) to 5% (SQ house dust mite sublingual tablet)) and an increased probability of having a mild allergic rhinitis day (from 16% (placebo) to 34% (SQ house dust mite sublingual tablet)). This article is protected by copyright. All rights reserved.

  11. Evaluation of the Snow Simulations from the Community Land Model, Version 4 (CLM4)

    NASA Technical Reports Server (NTRS)

    Toure, Ally M.; Rodell, Matthew; Yang, Zong-Liang; Beaudoing, Hiroko; Kim, Edward; Zhang, Yongfei; Kwon, Yonghwan

    2015-01-01

    This paper evaluates the simulation of snow by the Community Land Model, version 4 (CLM4), the land model component of the Community Earth System Model, version 1.0.4 (CESM1.0.4). CLM4 was run in an offline mode forced with the corrected land-only replay of the Modern-Era Retrospective Analysis for Research and Applications (MERRA-Land) and the output was evaluated for the period from January 2001 to January 2011 over the Northern Hemisphere poleward of 30 deg N. Simulated snow-cover fraction (SCF), snow depth, and snow water equivalent (SWE) were compared against a set of observations including the Moderate Resolution Imaging Spectroradiometer (MODIS) SCF, the Interactive Multisensor Snow and Ice Mapping System (IMS) snow cover, the Canadian Meteorological Centre (CMC) daily snow analysis products, snow depth from the National Weather Service Cooperative Observer (COOP) program, and Snowpack Telemetry (SNOTEL) SWE observations. CLM4 SCF was converted into snow-cover extent (SCE) to compare with MODIS SCE. It showed good agreement, with a correlation coefficient of 0.91 and an average bias of -1.54 x 10(exp 2) sq km. Overall, CLM4 agreed well with IMS snow cover, with the percentage of correctly modeled snow-no snow being 94%. CLM4 snow depth and SWE agreed reasonably well with the CMC product, with the average bias (RMSE) of snow depth and SWE being 0.044m (0.19 m) and -0.010m (0.04 m), respectively. CLM4 underestimated SNOTEL SWE and COOP snow depth. This study demonstrates the need to improve the CLM4 snow estimates and constitutes a benchmark against which improvement of the model through data assimilation can be measured.

  12. Dating of vein specularite using internal (U+Th)/He-4 isochrons

    NASA Astrophysics Data System (ADS)

    Wernicke, Rolf S.; Lippolt, Hans J.

    1994-03-01

    Hematite, an ubiquitous iron oxide, is commonly found enriched with uranium and other elements supplied by the ore solution from which it had formed. The decay of the incorporated uranium to stable lead produces alpha particles which become He-4 atoms via electron capture. In hematite this helium production may provide a convenient 'clock' which records the time elapsed since the iron oxide became closed enough to prevent quantitative helium escape (Wernicke and Lippolt, 1993a; 1993b). Recently, Lippolt et al. (1993) reported high retention qualities of specular hematite for He-4 over geologic periods of time (activation energies above 116 (KJ/mol) and diffusion coefficients smaller than 10(exp -30) sq m/s) at room temperature, and closure temperatures above 200 C). Here the concentrations of U and Th have been measured together with radiogenic He-4 at four different locations inside two specularites. The U-He concentrations co-varied sufficiently among the locations for an internal helium isochron of Late Jurassic age to be obtained from each specularite. The study suggests that specularite is a prolific chronometer and might allow a routine approach of the helium (isochron) method to obtain crystallization/cooling ages.

  13. Heat-Transfer and Pressure Measurements from a Flight Test of the Third 1/18-Scale Model of the Titan Intercontinental Ballistic Missile up to a Mach Number of 3.86 and Reynolds Number per Foot of 23.5 x 10(exp 6) and a Comparison with Heat Transfer

    NASA Technical Reports Server (NTRS)

    Graham, John B., Jr.

    1958-01-01

    Heat-transfer and pressure measurements were obtained from a flight test of a 1/18-scale model of the Titan intercontinental ballistic missile up to a Mach number of 3.86 and Reynolds number per foot of 23.5 x 10(exp 6) and are compared with the data of two previously tested 1/18-scale models. Boundary-layer transition was observed on the nose of the model. Van Driest's theory predicted heat-transfer coefficients reasonably well for the fully laminar flow but predictions made by Van Driest's theory for turbulent flow were considerably higher than the measurements when the skin was being heated. Comparison with the flight test of two similar models shows fair repeatability of the measurements for fully laminar or turbulent flow.

  14. Targeted Disruption of the kstD Gene Encoding a 3-Ketosteroid Δ1-Dehydrogenase Isoenzyme of Rhodococcus erythropolis Strain SQ1

    PubMed Central

    van der Geize, R.; Hessels, G. I.; van Gerwen, R.; Vrijbloed, J. W.; van der Meijden, P.; Dijkhuizen, L.

    2000-01-01

    Microbial phytosterol degradation is accompanied by the formation of steroid pathway intermediates, which are potential precursors in the synthesis of bioactive steroids. Degradation of these steroid intermediates is initiated by Δ1-dehydrogenation of the steroid ring structure. Characterization of a 2.9-kb DNA fragment of Rhodococcus erythropolis SQ1 revealed an open reading frame (kstD) showing similarity with known 3-ketosteroid Δ1-dehydrogenase genes. Heterologous expression of kstD yielded 3-ketosteroid Δ1-dehydrogenase (KSTD) activity under the control of the lac promoter in Escherichia coli. Targeted disruption of the kstD gene in R. erythropolis SQ1 was achieved, resulting in loss of more than 99% of the KSTD activity. However, growth on the steroid substrate 4-androstene-3,17-dione or 9α-hydroxy-4-androstene-3,17-dione was not abolished by the kstD gene disruption. Bioconversion of phytosterols was also not blocked at the level of Δ1-dehydrogenation in the kstD mutant strain, since no accumulation of steroid pathway intermediates was observed. Thus, inactivation of kstD is not sufficient for inactivation of the Δ1-dehydrogenase activity. Native polyacrylamide gel electrophoresis of cell extracts stained for KSTD activity showed that R. erythropolis SQ1 in fact harbors two activity bands, one of which is absent in the kstD mutant strain. PMID:10788377

  15. Energy Spectra and High Frequency Oscillations in 4U 0614+091

    NASA Technical Reports Server (NTRS)

    Ford, E. C.; Kaaret, P.; Chen, K.; Tavani, M.; Barret, D.; Bloser, P.; Grindlay, J.; Harmon, B. A.; Paciesas, W. S.; Zhang, S. N.

    1997-01-01

    We investigate the behavior of the high frequency quasi-periodic oscillations (QPOs) in 4U 0614+091, combining timing and spectral analysis of RXTE (Rossi X-ray Timing Explorer) observations. The energy spectrum of the source can be described by a power law plus a blackbody component. The blackbody has a variable temperature (kT approximately 0.8 to 1.4 keV) and accounts for 10 to 25% of the total energy flux. The power law flux and photon index also vary (F approximately 0.8 to 1.6 x 10(exp -9) erg/sq cm.s and alpha approximately 2.0 to 2.8 respectively). We find a robust correlation of the frequency of the higher frequency QPO with the flux of the blackbody. The source follows the same relation even in observations separated by several months. The QPO frequency does not have a similarly unique correlation with the total flux or the flux of the power law component. The RMS amplitudes of the higher frequency QPO rise with energy but are consistent with a constant for the lower frequency QPO. These results may be interpreted in terms of a beat frequency model for the production of the high frequency QPOs.

  16. Asymptotically scale-invariant occupancy of phase space makes the entropy Sq extensive

    PubMed Central

    Tsallis, Constantino; Gell-Mann, Murray; Sato, Yuzuru

    2005-01-01

    Phase space can be constructed for N equal and distinguishable subsystems that could be probabilistically either weakly correlated or strongly correlated. If they are locally correlated, we expect the Boltzmann-Gibbs entropy SBG ≡ -k Σi pi ln pi to be extensive, i.e., SBG(N) ∝ N for N → ∞. In particular, if they are independent, SBG is strictly additive, i.e., SBG(N) = NSBG(1), ∀N. However, if the subsystems are globally correlated, we expect, for a vast class of systems, the entropy Sq ≡ k[1 - Σi pqi]/(q - 1) (with S1 = SBG) for some special value of q ≠ 1 to be the one which is extensive [i.e., Sq(N) ∝ N for N → ∞]. Another concept which is relevant is strict or asymptotic scale-freedom (or scale-invariance), defined as the situation for which all marginal probabilities of the N-system coincide or asymptotically approach (for N → ∞) the joint probabilities of the (N - 1)-system. If each subsystem is a binary one, scale-freedom is guaranteed by what we hereafter refer to as the Leibnitz rule, i.e., the sum of two successive joint probabilities of the N-system coincides or asymptotically approaches the corresponding joint probability of the (N - 1)-system. The kinds of interplay of these various concepts are illustrated in several examples. One of them justifies the title of this paper. We conjecture that these mechanisms are deeply related to the very frequent emergence, in natural and artificial complex systems, of scale-free structures and to their connections with nonextensive statistical mechanics. Summarizing, we have shown that, for asymptotically scale-invariant systems, it is Sq with q ≠ 1, and not SBG, the entropy which matches standard, clausius-like, prescriptions of classical thermodynamics. PMID:16230624

  17. Embodied Agents, E-SQ and Stickiness: Improving Existing Cognitive and Affective Models

    NASA Astrophysics Data System (ADS)

    de Diesbach, Pablo Brice

    This paper synthesizes results from two previous studies of embodied virtual agents on commercial websites. We analyze and criticize the proposed models and discuss the limits of the experimental findings. Results from other important research in the literature are integrated. We also integrate concepts from profound, more business-related, analysis that deepens on the mechanisms of rhetoric in marketing and communication, and the possible role of E-SQ in man-agent interaction. We finally suggest a refined model for the impacts of these agents on web site users, and limits of the improved model are commented.

  18. Rapid evaluation in whole blood culture of regimens for XDR-TB containing PNU-100480 (sutezolid), TMC207, PA-824, SQ109, and pyrazinamide.

    PubMed

    Wallis, Robert S; Jakubiec, Wesley; Mitton-Fry, Mark; Ladutko, Lynn; Campbell, Sheldon; Paige, Darcy; Silvia, Annette; Miller, Paul F

    2012-01-01

    There presently is no rapid method to assess the bactericidal activity of new regimens for tuberculosis. This study examined PNU-100480, TMC207, PA-824, SQ109, and pyrazinamide, singly and in various combinations, against intracellular M. tuberculosis, using whole blood culture (WBA). The addition of 1,25-dihydroxy vitamin D facilitated detection of the activity of TMC207 in the 3-day cultures. Pyrazinamide failed to show significant activity against a PZA-resistant strain (M. bovis BCG), and was not further considered. Low, mid, and high therapeutic concentrations of each remaining drug were tested individually and in a paired checkerboard fashion. Observed bactericidal activity was compared to that predicted by the sum of the effects of individual drugs. Combinations of PNU-100480, TMC207, and SQ109 were fully additive, whereas those including PA-824 were less than additive or antagonistic. The cumulative activities of 2, 3, and 4 drug combinations were predicted based on the observed concentration-activity relationship, published pharmacokinetic data, and, for PNU-100480, published WBA data after oral dosing. The most active regimens, including PNU-100480, TMC207, and SQ109, were predicted to have cumulative activity comparable to standard TB therapy. Further testing of regimens including these compounds is warranted. Measurement of whole blood bactericidal activity can accelerate the development of novel TB regimens.

  19. Experimental Surface Pressure Data Obtained on 65 deg Delta Wing Across Reynolds Number and Mach Number Ranges. Vol. 4: Large-radius leading edge

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Luckring, James M.

    1996-01-01

    An experimental wind tunnel test of a 65 deg delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 120 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6) and 60 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.

  20. 2006 SQ372: A Likely Long-Period Comet from the Inner Oort Cloud

    SciTech Connect

    Kaib, Nathan A.; Becker, Andrew C.; Jones, R.Lynne; Puckett, Andrew W.; Bizyaev, Dmitry; Dilday, Benjamin; Frieman, Joshua A.; Oravetz, Daniel J.; Pan, Kaike; Quinn, Thomas; Schneider, Donald P.; /Penn State U., Astron. Astrophys. /Apache Point Observ.

    2009-01-01

    We report the discovery of a minor planet (2006 SQ{sub 372}) on an orbit with a perihelion of 24 AU and a semimajor axis of 796 AU. Dynamical simulations show that this is a transient orbit and is unstable on a timescale of {approx}200 Myr. Falling near the upper semimajor axis range of the scattered disk and the lower semimajor axis range of the Oort Cloud, previous membership in either class is possible. By modeling the production of similar orbits from the Oort Cloud as well as from the scattered disk, we find that the Oort Cloud produces 16 times as many objects on SQ{sub 372}-like orbits as the scattered disk. Given this result, we believe this to be the most distant long-period comet (LPC) ever discovered. Furthermore, our simulation results also indicate that 2000 OO{sub 67} has had a similar dynamical history. Unaffected by the 'Jupiter-Saturn Barrier', these two objects are most likely LPCs from the inner Oort Cloud.

  1. Assessments of Sequential Intensity Modulated Radiation Therapy Boost (SqIB) Treatments Using HART

    NASA Astrophysics Data System (ADS)

    Pyakuryal, Anil

    2009-05-01

    A retrospective study was pursued to evaluate the SqIB treatments performed on ten head and neck cancer patients(n=10).Average prescription doses (PDs) of 39 Gy,15Gy and 17.8Gy were delivered consecutively from larger to smaller planning target volumes(ptvs) in three different treatment plans using 6 MV X-ray photon beams from a Linear accelerator (SLA Linac, Elekta) on BID weak on-weak off schedules. These plans were statistically evaluated on basis of plan indices (PIs),dose response of targets and critical structures, and dose tolerance(DT) of various organs utilizing the DVH analysis automated software known as Histogram Analysis in Radiation Therapy-HART(S.Jang et al., 2008, Med Phys 35, p.2812). Mean SqIB PIs were found consistent with the reported values for varying radio-surgical systems.The 95.5%(n=10)of each ptvs and the gross tumor volume also received 95% (n=10)of PDs in treatments. The average volume of ten organs (N=10) affected by each PDs shrank with decreasing size of ptvs in above plans.A largest volume of Oropharynx (79%,n=10,N=10) irradiated at PD, but the largest volume of Larynx (98%, n=10, N=10) was vulnerable to DT of structure (TD50).Thus, we have demonstrated the efficiency and accuracy of HART in the assessment of Linac based plans in radiation therapy treatments of cancer.

  2. Peculiarities of change of Sq-variation in solar activity cycle

    NASA Astrophysics Data System (ADS)

    Pogrebnoy, V.; Malosiev, T.

    It has been considered, that a dependence of Sq-variation on R (relative sunspot numbers) is described by linear function. However these conclusions have been based on analysis of data collected during the periods spanning 1922-1932 and 1933-1943, when peak value of R did not exceed 115. Therefore it is of interest to examine the dependence of Sq-variation on R including period 1957-1958, when R reached the magnitude of 250. For this purpose, the average annual diurnal amplitude (a difference between midday and midnight values) of Sq-variations according to five international quiet days, were computed. The data from three observatories having long observational series and located in different latitude zones were used, namely: Rude Skov (middle latitude observatory) from 1907 to 1961; Alibag (low latitude observatory) from 1900 to 1959; Huancayo (equatorial observatory) from 1920 to 1964. It was found that average annual diurnal amplitude increases in proportion to R only in the range of 0

  3. An antireflection transparent conductor with ultralow optical loss (<2 %) and electrical resistance (<6 Ω sq-1)

    NASA Astrophysics Data System (ADS)

    Maniyara, Rinu Abraham; Mkhitaryan, Vahagn K.; Chen, Tong Lai; Ghosh, Dhriti Sundar; Pruneri, Valerio

    2016-12-01

    Transparent conductors are essential in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and solar cells. Here we demonstrate a transparent conductor with optical loss of ~1.6%, that is, even lower than that of single-layer graphene (2.3%), and transmission higher than 98% over the visible wavelength range. This was possible by an optimized antireflection design consisting in applying Al-doped ZnO and TiO2 layers with precise thicknesses to a highly conductive Ag ultrathin film. The proposed multilayer structure also possesses a low electrical resistance (5.75 Ω sq-1), a figure of merit four times larger than that of indium tin oxide, the most widely used transparent conductor today, and, contrary to it, is mechanically flexible and room temperature deposited. To assess the application potentials, transparent shielding of radiofrequency and microwave interference signals with ~30 dB attenuation up to 18 GHz was achieved.

  4. A Comprehensive Spectral Analysis of the X-Ray Pulsar 4U 1907+09 from Two Observations with the Suzaku X-Ray Observatory

    NASA Technical Reports Server (NTRS)

    Rivers, Elizabeth; Markowitz, Alex; Pottschmidt, Katja; Roth, Stefanie; Barragan, Laura; Furst, Felix; Suchy, Slawomir; Kreykenbohm, Ingo; Wilms, Jorn; Rothschild, Richard

    2009-01-01

    We present results from two observations of the wind-accreting X-ray pulsar 4U 1907+09 using the Suzaku observatory, The broadband time-averaged spectrum allows us to examine the continuum emission of the source and the cyclotron resonance scattering feature at approx. 19 keV. Additionally, using the narrow CCD response of Suzaku near 6 ke V allows us to study in detail the Fe K bandpass and to quantify the Fe Kp line for this source for the first time. The source is absorbed by fully-covering material along the line of sight with a column density of N(sub H) approx. 2 x 10(exp 22)/sq cm, consistent with a wind accreting geometry, and a high Fe abundance (approx. 3 - 4 x solar). Time and phase-resolved analyses allow us to study variations in the source spectrum. In particular, dips found in the 2006 observation which are consistent with earlier observations occur in the hard X-ray bandpass, implying a variation of the whole continuum rather than occultation by intervening material, while a dip near the end of the 2007 observation occurs mainly in the lower energies implying an increase in NH along the line of sight, perhaps indicating clumpiness in the stellar wind

  5. Purification, crystallization and preliminary X-ray crystallographic analysis of 3-ketosteroid Δ1-dehydrogenase from Rhodococcus erythropolis SQ1

    PubMed Central

    Rohman, Ali; van Oosterwijk, Niels; Dijkstra, Bauke W.

    2012-01-01

    3-Ketosteroid Δ1-dehydrogenase plays a crucial role in the early steps of steroid degradation by introducing a double bond between the C1 and C2 atoms of the A-ring of its 3-ketosteroid substrates. The 3-ketosteroid Δ1-dehydrogenase from Rhodococcus erythropolis SQ1, a 56 kDa flavoprotein, was crystallized using the sitting-drop vapour-diffusion method at room temperature. The crystals grew in various buffers over a wide pH range (from pH 5.5 to 10.5), but the best crystallization condition consisted of 2%(v/v) PEG 400, 0.1 M HEPES pH 7.5, 2.0 M ammonium sulfate. A native crystal diffracted X-rays to 2.0 Å resolution. It belonged to the primitive orthorhombic space group P212121, with unit-cell parameters a = 107.4, b = 131.6, c = 363.2 Å, and contained eight molecules in the asymmetric unit. The initial structure of the enzyme was solved using multi-wavelength anomalous dispersion (MAD) data collected from a Pt-derivatized crystal. PMID:22691786

  6. Stratospheric OClO and NO2 measured by groundbased UV/Vis-spectroscopy in Greenland in January and February 1990 and 1991

    NASA Technical Reports Server (NTRS)

    Roth, A.; Perner, D.

    1994-01-01

    Groundbased UV/Vis-spectroscopy of zenith scattered sunlight was performed at Sondre Stromfjord (Greenland) during Jan/Feb 1990 and Jan/Feb 1991. Considerable amounts of OClO were observed during both campaigns. Maximum OClO vertical column densities at 92 deg solar zenith angle (SZA) were 7.4 x 10(exp 13) molec/sq cm in 1990 and 5.7 x 10(exp 13) molec/sq cm in 1991 (chemical enhancement is included in the calculation of the air mass factor (AMF)). A threshold seems to exist for OClO detection: OClO was detected on every day when the potential vorticity at the 475 K level of potential temperature was higher than 35 x 10(exp -6)Km(exp 2)kg(exp -1)s(exp -1). NO2 vertical columns lower than 1 x 10(exp 15) molec/sq cm were frequently observed in both winters.

  7. A 20 sq CM CCD mosaic camera for a dark matter search. Part 1: Mechanics, optics and cryogeny

    NASA Astrophysics Data System (ADS)

    Arnaud, M.; Aubourg, E.; Bareyre, P.; Brehin, S.; Caridroit, R.; de Kat, J.; Dispau, G.; Djidi, K.; Gros, M.; Lachieze-Rey, M.

    1994-09-01

    A 20 sq cm charge coupled device (CCD) mosaic camera has been especially built to search for dark galactic halo objects by the gravitational microlensing effect. The sensitive area is made of 16 edge-buttable CCDs developed by Thomson-CTS, with 23x23 sq micrometer pixels. The 35 kg camera housing and mechanical equipment is presented. The associated electronics and data acquisition system are described in a separate paper. The camera resides at the focal plane of a 40 cm, f/10, Ferson reflector. The instrument has been in operation since December 1991 at the European Southern Observatory's (ESO) La Silla Observatory.

  8. Spatial and Temporal Variations of Solar Quiet Daily Sq Variation and Equatorial Electrojet Over Africa: Results From International Heliophysical Year

    NASA Astrophysics Data System (ADS)

    Rabiu, A.; Yumoto, K.; Bello, O.

    2010-12-01

    Space Environment Research Centre of Kyushu University, Japan, installed 13 units of Magnetic Data Acquisition Systems MAGDAS over Africa during the International Heliophysical Year IHY. Magnetic records from 10 stations along the African 96o Magnetic Meridian (Geographical 30o - 40o East) were examined for Solar quiet daily Sq variation in the three geomagnetic field components H, D and Z. Spatial variations of Sq in the geomagnetic components were examined. Signatures of equatorial electrojet and worldwide Sq were identified and studied in detail. H field experienced more variation within the equatorial electrojet zone. Diurnal and seasonal variations of the geomagnetic variations in the three components were discussed. Levels of inter-relationships between the Sq and its variability in the three components were statistically derived and interpreted in line with the mechanisms responsible for the variations of the geomagnetic field. Data from 2 magnetic observatories within equatorial electrojet EEJ strip and 2 stations outside the EEJ strip were employed to evaluate and study the signatures of the Equatorial electrojet over the African sector. The transient variations of the EEJ at two almost parallel axes using Lagos-Ilorin and Nairobi-Addis pairs were examined. The EEJ appear stronger in East than West Africa. The magnitudes and patterns of variation of EEJ strength along the two axes were examined for any simultaneity or otherwise of responses to ionospheric processes. The flow gradient of EEJ along the African sector was estimated and its diurnal variation studied.

  9. Influence of insecticides and reflective mulch on watermelon vine decline caused by squash vein yellowing virus (SqVYV)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Watermelon vine decline (WVD) caused by the whitefly-transmitted Squash vein yellowing virus (SqVYV) has been a major limiting factor in watermelon production in southwest and west-central Florida for the past several years. Symptoms of WVD typically manifest as sudden decline of vines a few weeks ...

  10. Absorption of water and lubricating oils into porous nylon

    NASA Technical Reports Server (NTRS)

    Bertrand, P. A.

    1995-01-01

    Oil and water absorption from air into sintered porous nylon can be described by infiltration into the pores of the material. This process can be modeled by a diffusion-like mechanism. For water absorption, we find a formal diffusion coefficient of 1.5 x 10(exp -4)sq cm/min when the nylon is initially dry. The diffusion coefficient is 4 x 10(exp -6)sq cm/min when the nylon is oil-impregnated prior to air exposure. In a 52% RH atmosphere, dry nylon absorbs 3% w/w water, and oil-impregnated nylon absorbs 0.6% w/w water. For oil absorption there are three steps: (1) surface absorption and infiltration into (2) larger and (3) smaller pores. Surface absorption is too fast to be measured in these experiments. The diffusion coefficient for the second step is 6 x 10(exp -4)sq cm/min for SRG-60 oil into dry nylon and 4 x 10(exp -4)sq cm/min for air-equilibrated nylon. The diffusion coefficient for the third step is about 1 x 10(exp -6)sq cm/min for both cases. The total amount of oil absorbed is 31% w/w. The interaction between water and nylon is not as strong as that between water and cotton-phenolic: oil can replace water, and only a small amount of water can enter previously oil-impregnated nylon.

  11. Design, Development and Flight Testing of the U.S. Army 4200 sq ft Parafoil Recovery System

    NASA Technical Reports Server (NTRS)

    Bennett, Thomas W.; Fox, Roy, Jr.

    2005-01-01

    The purpose of this paper is to describe the design, development and flight-testing of the U.S. Army 4200 sq ft parafoil recovery system built under NASA Contract NAS 9-00076. The 4200 f? parafoil described herein was a potential candidate to fulfill the U.S. Army requirement for a 10,000 lb useable payload precision guided recovery system. Design heritage as well as specific features, like lower surface inlets, confluence fitting, upper surface energy modulator design, deployment bag design and 60 ft diameter Ringslot drogue will be discussed. Initial flight test results, ground testing of various components to verify design margin and configuration changes will also be discussed. The 4200 sq ft parafoil recovery system completed three flight tests during 2003 at payload weights of over 15,000 Ibs

  12. Changes of the Sq Quiet Daily Variations of the Geomagnetic Field as a Function of Time of Year and Latitude,

    DTIC Science & Technology

    1981-01-01

    obtained at Huancayo , Honolulu, and Baker Lake. The mean and median values of the correlation coefficient, all stations considered, were (respectively...percentage errors for all three components combined whereas, Huancayo , Tatuoca, Tucson, and Baker Lake show reasonably low all all-over values of...best, Paramaribo and Fredericksburg are very good, and Huancayo and Baker Lake are good. For future studies on induced effects of Sq these five

  13. On the possibility of an alpha-sq omega-type dynamo in a thin layer inside the sun

    NASA Technical Reports Server (NTRS)

    Choudhuri, Arnab Rai

    1990-01-01

    If the solar dynamo operates in a thin layer of 10,000-km thickness at the interface between the convection zone and the radiative core, using the facts that the dynamo should have a period of 22 years and a half-wavelength of 40 deg in the theta-direction, it is possible to impose restrictions on the values which various dynamo parameters are allowed to have. It is pointed out that the dynamo should be of alpha-sq omega nature, and kinematical calculations are presented for free dynamo waves and for dynamos in thin rectangular slabs with appropriate boundary conditions. An alpha-sq omega dynamo is expected to produce a significant poloidal field which does not leak to the solar surface. It is found that the turbulent diffusity eta and alpha-coefficient are restricted to values within about a factor of 10, the median values being eta of about 10 to the 10th sq cm/sec and alpha of about 10 cm/sec. On the basis of mixing length theory, it is pointed out that such values imply a reasonable turbulent velocity of the order 30 m/s, but rather small turbulent length scales like 300 km.

  14. Comparative proteomic analysis of a membrane-enriched fraction from flag leaves reveals responses to chemical hybridization agent SQ-1 in wheat

    PubMed Central

    Song, Qilu; Wang, Shuping; Zhang, Gaisheng; Li, Ying; Li, Zheng; Guo, Jialin; Niu, Na; Wang, Junwei; Ma, Shoucai

    2015-01-01

    The induction of wheat male fertile lines by using the chemical hybridizing agent SQ-1 (CHA-SQ-1) is an effective approach in the utilization of heterosis; however, the molecular basis of male fertility remains unknown. Wheat flag leaves are the initial receptors of CHA-SQ-1 and their membrane structure plays a vital role in response to CHA-SQ-1 stress. To investigate the response of wheat flag leaves to CHA-SQ-1 stress, we compared their quantitative proteomic profiles in the absence and presence of CHA-SQ-1. Our results indicated that wheat flag leaves suffered oxidative stress during CHA-SQ-1 treatments. Leaf O2-, H2O2, and malonaldehyde levels were significantly increased within 10 h after CHA-SQ-1 treatment, while the activities of major antioxidant enzymes such as superoxide dismutase, catalase, and guaiacol peroxidase were significantly reduced. Proteome profiles of membrane-enriched fraction showed a change in the abundance of a battery of membrane proteins involved in multiple biological processes. These variable proteins mainly impaired photosynthesis, ATP synthesis protein mechanisms and were involved in the response to stress. These results provide an explanation of the relationships between membrane proteomes and anther abortion and the practical application of CHA for hybrid breeding. PMID:26379693

  15. SQ109 targets MmpL3, a membrane transporter of trehalose monomycolate involved in mycolic acid donation to the cell wall core of Mycobacterium tuberculosis.

    PubMed

    Tahlan, Kapil; Wilson, Regina; Kastrinsky, David B; Arora, Kriti; Nair, Vinod; Fischer, Elizabeth; Barnes, S Whitney; Walker, John R; Alland, David; Barry, Clifton E; Boshoff, Helena I

    2012-04-01

    SQ109, a 1,2-diamine related to ethambutol, is currently in clinical trials for the treatment of tuberculosis, but its mode of action remains unclear. Here, we demonstrate that SQ109 disrupts cell wall assembly, as evidenced by macromolecular incorporation assays and ultrastructural analyses. SQ109 interferes with the assembly of mycolic acids into the cell wall core of Mycobacterium tuberculosis, as bacilli exposed to SQ109 show immediate inhibition of trehalose dimycolate (TDM) production and fail to attach mycolates to the cell wall arabinogalactan. These effects were not due to inhibition of mycolate synthesis, since total mycolate levels were unaffected, but instead resulted in the accumulation of trehalose monomycolate (TMM), the precursor of TDM and cell wall mycolates. In vitro assays using purified enzymes showed that this was not due to inhibition of the secreted Ag85 mycolyltransferases. We were unable to achieve spontaneous generation of SQ109-resistant mutants; however, analogs of this compound that resulted in similar shutdown of TDM synthesis with concomitant TMM accumulation were used to spontaneously generate resistant mutants that were also cross-resistant to SQ109. Whole-genome sequencing of these mutants showed that these all had mutations in the essential mmpL3 gene, which encodes a transmembrane transporter. Our results suggest that MmpL3 is the target of SQ109 and that MmpL3 is a transporter of mycobacterial TMM.

  16. The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). I. The UV luminosity function of the central 12 sq. deg

    NASA Astrophysics Data System (ADS)

    Boselli, A.; Boissier, S.; Heinis, S.; Cortese, L.; Ilbert, O.; Hughes, T.; Cucciati, O.; Davies, J.; Ferrarese, L.; Giovanelli, R.; Haynes, M. P.; Baes, M.; Balkowski, C.; Brosch, N.; Chapman, S. C.; Charmandaris, V.; Clemens, M. S.; Dariush, A.; De Looze, I.; di Serego Alighieri, S.; Duc, P.-A.; Durrell, P. R.; Emsellem, E.; Erben, T.; Fritz, J.; Garcia-Appadoo, D. A.; Gavazzi, G.; Grossi, M.; Jordán, A.; Hess, K. M.; Huertas-Company, M.; Hunt, L. K.; Kent, B. R.; Lambas, D. G.; Lançon, A.; MacArthur, L. A.; Madden, S. C.; Magrini, L.; Mei, S.; Momjian, E.; Olowin, R. P.; Papastergis, E.; Smith, M. W. L.; Solanes, J. M.; Spector, O.; Spekkens, K.; Taylor, J. E.; Valotto, C.; van Driel, W.; Verstappen, J.; Vlahakis, C.; Vollmer, B.; Xilouris, E. M.

    2011-04-01

    The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) is a complete blind survey of the Virgo cluster covering ~40 sq. deg in the far UV (FUV, λeff = 1539 Å, Δλ = 442 Å) and ~120 sq. deg in the near UV (NUV, λeff = 2316 Å, Δλ = 1060 Å). The goal of the survey is to study the ultraviolet (UV) properties of galaxies in a rich cluster environment, spanning a wide luminosity range from giants to dwarfs, and regardless of prior knowledge of their star formation activity. The UV data will be combined with those in other bands (optical: NGVS; far-infrared - submm: HeViCS; HI: ALFALFA) and with our multizone chemo-spectrophotometric models of galaxy evolution to make a complete and exhaustive study of the effects of the environment on the evolution of galaxies in high density regions. We present here the scientific objectives of the survey, describing the observing strategy and briefly discussing different data reduction techniques. Using UV data already in-hand for the central 12 sq. deg we determine the FUV and NUV luminosity functions of the Virgo cluster core for all cluster members and separately for early- and late-type galaxies and compare it to the one obtained in the field and other nearby clusters (Coma, A1367). This analysis shows that the FUV and NUV luminosity functions of the core of the Virgo clusters are flatter (α ~ -1.1) than those determined in Coma and A1367. We discuss the possible origin of this difference. Table 1 is only available in electronic form at http://www.aanda.org

  17. Search for chargino-neutralino production in pp collisions at sq rt[s] = 1.96 TeV.

    PubMed

    Aaltonen, T; Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carillo, S; Carlsmith, D; Carosi, R; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, I; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Cilijak, M; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Coca, M; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Almenar, C Cuenca; Cuevas, J; Culbertson, R; Cully, J C; Daronco, S; Datta, M; D'Auria, S; Davies, T; Dagenhart, D; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'orso, M; Delli Paoli, F; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Dörr, C; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, I; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garcia, J E; Garberson, F; Garfinkel, A F; Gay, C; Gerberich, H; Gerdes, D; Giagu, S; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Giurgiu, G; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Goldstein, J; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; da Costa, J Guimaraes; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Holloway, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jang, D; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Karchin, P E; Kato, Y; Kemp, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraan, A C; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lu, R-S; Lucchesi, D; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marginean, R; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Matsunaga, H; Mattson, M E; Mazini, R; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyamoto, A; Moed, S; Moggi, N; Mohr, B; Moon, C S; Moore, R; Morello, M; Fernandez, P Movilla; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savard, P; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyrla, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; Staveris-Polykalas, A; Denis, R St; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tsuno, S; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vazquez, F; Velev, G; Vellidis, C; Veramendi, G; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Vollrath, I; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner, J; Wagner, W; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zhou, J; Zucchelli, S

    2007-11-09

    We present a search for associated production of the chargino and neutralino supersymmetric particles using up to 1.1 fb{-1} of integrated luminosity collected by the CDF II experiment at the Tevatron pp collider at sq rt[s]=1.96 TeV. We analyze events with a large transverse momentum imbalance and either three charged leptons or two charged leptons of the same electric charge. The numbers of observed events are consistent with standard model expectations. Upper limits on the production cross section are derived in different theoretical models.

  18. Quotients of AdSp+1×Sq: Causally well-behaved spaces and black holes

    NASA Astrophysics Data System (ADS)

    Figueroa-O'Farrill, José; Madden, Owen; Ross, Simon F.; Simón, Joan

    2004-06-01

    Starting from the recent classification of quotients of Freund-Rubin backgrounds in string theory of the type AdSp+1×Sq by one-parameter subgroups of isometries, we investigate the physical interpretation of the associated quotients by discrete cyclic subgroups. We establish which quotients have well-behaved causal structures, and of those containing closed timelike curves, which have interpretations as black holes. We explain the relation to previous investigations of quotients of asymptotically flat spacetimes and plane waves, of black holes in AdS spacetimes, and of Gödel-type universes.

  19. Fabrication and qualification of roughness reference samples for industrial testing of surface roughness levels below 0.5 nm Sq

    NASA Astrophysics Data System (ADS)

    Faehnle, O.; Langenbach, E.; Zygalsky, F.; Frost, F.; Fechner, R.; Schindler, A.; Cumme, M.; Biskup, H.; Wünsche, C.; Rascher, R.

    2015-08-01

    Applying reactive ion beam etching (RIBE) processes at the Leibniz Institute of Surface Modification (IOM), several reference samples to be used in industry for calibrating of roughness testing equipment have been generated with the smoothest sample featuring 0.1 nm rms Sq. Subsequently these reference samples have been measured cross-site applying atomic force microscopy (AFM), white light interferometry (WLI), Nomarski1 microscopy (NM) and scatterometry (iTIRM2) determining the appropriate range of measurable rms surface roughness for each industrial measuring device.

  20. Charge Transfer Between Ground-State N(2+) and H2, N2, and CO at Electron-Volt Energies

    NASA Technical Reports Server (NTRS)

    Fang, Z.; Kwong, Victor H. S.

    1997-01-01

    The charge-transfer rate coefficients for reactions of N(2+)(2 S(sup 2)2p(sup 2)P(sup 0)) with H2, N2, and CO are measured using ion storage. A cylindrical rf ion trap was used to store N(2+) ions produced by laser ablation of a solid titanium nitride target. The rate coefficients were derived from the decay rate of the ion signal. The rate coefficients for the above three reactions are 3.38(0.35) x 10(exp -11)sq sm/s at T(sub equiv.)=2.9 x 10(exp 3) K, 2.10(0.18) x 10(exp -9)sq sm/s at T(sub equiv.) = 1.3 x 10(exp 4) K, and 3.37(0.29) x 10(exp -9)sq cm/s at T(sub equiv.) = 1.3 x 10(exp 4) K, respectively. No theoretical or other experimental values are available at this energy range.

  1. Spectral and Timing Nature of the Symbiotic X-Ray Binary 4U 1954+319: The Slowest Rotating Neutron Star in AN X-Ray Binary System

    NASA Technical Reports Server (NTRS)

    Enoto, Teruaki; Sasano, Makoto; Yamada, Shin'Ya; Tamagawa, Toru; Makishima, Kazuo; Pottschmidt, Katja; Marcu, Diana; Corbet, Robin H. D.; Fuerst, Felix; Wilms, Jorn

    2014-01-01

    The symbiotic X-ray binary (SyXB) 4U 1954+319 is a rare system hosting a peculiar neutron star (NS) and an M-type optical companion. Its approx. 5.4 hr NS spin period is the longest among all known accretion-powered pulsars and exhibited large (is approx. 7%) fluctuations over 8 yr. A spin trend transition was detected with Swift/BAT around an X-ray brightening in 2012. The source was in quiescent and bright states before and after this outburst based on 60 ks Suzaku observations in 2011 and 2012. The observed continuum is well described by a Comptonized model with the addition of a narrow 6.4 keV Fe-K alpha line during the outburst. Spectral similarities to slowly rotating pulsars in high-mass X-ray binaries, its high pulsed fraction (approx. 60%-80%), and the location in the Corbet diagram favor high B-field (approx. greater than 10(exp12) G) over a weak field as in low-mass X-ray binaries. The observed low X-ray luminosity (10(exp33)-10(exp35) erg s(exp-1)), probable wide orbit, and a slow stellar wind of this SyXB make quasi-spherical accretion in the subsonic settling regime a plausible model. Assuming a approx. 10(exp13) G NS, this scheme can explain the approx. 5.4 hr equilibrium rotation without employing the magnetar-like field (approx. 10(exp16) G) required in the disk accretion case. The timescales of multiple irregular flares (approx. 50 s) can also be attributed to the free-fall time from the Alfv´en shell for a approx. 10(exp13) G field. A physical interpretation of SyXBs beyond the canonical binary classifications is discussed.

  2. Lightcurves for 1896 Beer, 2574 Ladoga, 3301 Jansje, 3339 Treshnikov 3833 Calingasta, 3899 Wichterle, 4106 Nada, 4801 Ohre, 4808 Ballaero, and (8487) 1989 SQ.

    NASA Astrophysics Data System (ADS)

    Owings, Larry E.

    2013-01-01

    Lightcurve observations have yielded period determinations for the following asteroids: 1896 Beer, 2574 Ladoga, 3301 Jansje, 3339 Treshnikov, 3833 Calingasta, 3899 Wichterle, 4106 Nada, 4801 Ohre, 4808 Ballaero, and (8487) 1989 SQ.

  3. Neutron-capture Cl-36, Ca-41, Ar-36, and Sm-150 in large chondrites: Evidence for high fluences of thermalized neutrons

    NASA Technical Reports Server (NTRS)

    Bogard, D. D.; Nyquist, L. E.; Bansal, B. M.; Garrison, D. H.; Wiesmann, H.; Herzog, G. F.; Albrecht, A. A.; Vogt, S.; Klein, J.

    1995-01-01

    We have measured significant concentrations of Cl-36, Ca-41, Ar-36 from decay of Cl-36, and Sm-150 produced from the capture of thermalized neutrons in the large Chico L6 chondrite. Activities of Cl-36 and Ca-41, corrected for a high-energy spallogenic component and a terrestrial age of approximately 50 ka, give average neutron-capture production rates of 208 atoms/min/g-Cl and 1525 atoms/min/kg-Ca, which correspond to thermal neutron (n) fluxes of 6.2 n/sq cm/s and 4.3 n/sq cm/s, respectively. If sustained for the approximately 65 Ma single-stage, cosmic ray exposure age of Chico, these values correspond to thermal neutron fluences of approximately 1.3 x 10(exp 16) and 0.8 x 10(exp 16) n/sq cm for Cl-36 and Ca-41, respectively. Stepwise temperature extraction of Ar in Chico impact melt shows Ar-36/Ar-38 ratios as large as approximately 9. The correlation of high Ar-36/Ar-38 with high Cl/Ca phases in neutron-irradiated Chico indicates that the excess Ar-36 above that expected from spallation is due to decay of neutron-produced Cl-36. Excess Ar-36 in Chico requires a thermal neutron fluence of 0.9-1.7 x 10(exp 16) n/sq cm. Decreases in Sm-149/Sm-152 due to neutron-capture by Sm-149 correlate with increases in Sm-150/Sm-152 for three samples of Chico, and one of the Torino H-chondrite. The 0.08% decrease in Sm-149 shown by Chico corresponds to a neutron fluence of 1.23 x 10(exp 16) n/sq cm. This fluence derived from Sm considers capture of epithermal neutrons and effects of chemical composition on the neutron energy distribution. Excess Ar-36 identified in the Arapahoe, Bruderheim, and Torino chondrites and the Shallowater aubrite suggest exposure to neutron fluences of approximately 0.2-0.2 x 10(exp 16) n/sq cm. Depletion of Sm-149 in Torino and the LEW86010 angrite suggest neutron fluences of 0.8 x 10(exp 16) n/sq cm and 0.25 x 10(exp 16) n/sq cm, respectively. Neutron fluences of approximately 10(exp 16) n/sq cm in Chico are almost as large as those previously

  4. High Transverse Momentum Triggered Correlations over a Large Pseudorapidity Acceptance in Au+Au Collisions at sq root(s{sub NN})=200 GeV

    SciTech Connect

    Alver, B.; Ballintijn, M.; Busza, W.; Decowski, M. P.; Gulbrandsen, K.; Henderson, C.; Kane, J. L.; Kulinich, P.; Li, W.; Loizides, C.; Reed, C.; Roland, C.; Roland, G.; Stephans, G. S. F.; Vale, C.; Nieuwenhuizen, G. J. van; Vaurynovich, S. S.; Verdier, R.; Veres, G. I.; Wenger, E.

    2010-02-12

    A measurement of two-particle correlations with a high transverse momentum trigger particle (p{sub T}{sup trig}>2.5 GeV/c) is presented for Au+Au collisions at sq root(s{sub NN})=200 GeV over the uniquely broad longitudinal acceptance of the PHOBOS detector (-4<{Delta}{eta}<2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all {Delta}{eta}. As in p+p collisions, the near side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in {Delta}{eta} and known as the 'ridge' is found to reach at least |{Delta}{eta}|approx =4. The ridge yield is largely independent of {Delta}{eta} over the measured range, and it decreases towards more peripheral collisions. For the chosen p{sub T}{sup trig} cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.

  5. Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

    NASA Astrophysics Data System (ADS)

    Yamazaki, Y.; Maute, A.

    2016-09-01

    A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μA/m2 flowing on the sunlit side of the E-region ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the non-specialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

  6. Sq and EEJ—A Review on the Daily Variation of the Geomagnetic Field Caused by Ionospheric Dynamo Currents

    NASA Astrophysics Data System (ADS)

    Yamazaki, Y.; Maute, A.

    2017-03-01

    A record of the geomagnetic field on the ground sometimes shows smooth daily variations on the order of a few tens of nano teslas. These daily variations, commonly known as Sq, are caused by electric currents of several μ A/m2 flowing on the sunlit side of the E-region ionosphere at about 90-150 km heights. We review advances in our understanding of the geomagnetic daily variation and its source ionospheric currents during the past 75 years. Observations and existing theories are first outlined as background knowledge for the non-specialist. Data analysis methods, such as spherical harmonic analysis, are then described in detail. Various aspects of the geomagnetic daily variation are discussed and interpreted using these results. Finally, remaining issues are highlighted to provide possible directions for future work.

  7. Infrared photodetectors with tailorable response due to resonant plasmon absorption in epitaxial silicide particles embedded in silicon

    NASA Technical Reports Server (NTRS)

    Fathauer, R. W.; Dejewski, S. M.; George, T.; Jones, E. W.; Krabach, T. N.; Ksendzov, A.

    1993-01-01

    Tailorable infrared photoresponse in the 1-2 micron range are demonstrated in a device incorporating electrically floating metal silicide particles. Photons absorbed by excitation of the metallic-particle surface plasmon are shown to contribute to the photoresponse. Quantum efficiencies of roughly 0.2 percent are measured at 77 K, with dark currents of less than 2 nA/sq cm at a reverse bias of 1 V and detectivities of 4 x 10 exp 9 - 8 x 10 exp 9 cm sq rt Hz/W are obtained.

  8. Fractionation of hydrogen and deuterium on Venus due to collisional ejection

    NASA Astrophysics Data System (ADS)

    Gurwell, M. A.; Yung, Y. L.

    1993-02-01

    The collisional ejection process for hydrogen on Venus is reanalyzed. Improved values for the efficiency of H and D escape as a function of the ionospheric temperature are reported. It is proposed that the reduction of the hydrogen flux for collisional ejection be reduced from 8 to 3.5 x 10 exp 6/sq cm/s, and a revised D/H fractional factor of 0.47 due to collisional ejection is suggested. The resulting deuterium flux is 3.1 x 10 exp 4/sq cm/s, roughly six times the flux due to charge exchange, making collisional ejection the dominant escape mechanism for deuterium on Venus.

  9. A Catalog of Soft X-Ray Shadows, and More Contemplation of the 1/4 KeV Background

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Freyberg, M. J.; Kuntz, K. D.; Sanders, W. T.

    1999-01-01

    This paper presents a catalog of shadows in the 1/4 keV soft X-ray diffuse background 4 (SXRB) that were identified by a comparison between ROSAT All-Sky Survey maps and DIRB&corrected IRAS 100 micron maps. These "shadows" are the negative correlations between the surface brightness of the SXRB and the column density of the Galactic interstellar medium (ISIM) over limited angular regions (a few degrees in extent). We have compiled an extensive but not exhaustive set of 378 shadows in the polar regions of the Galaxy (Absolute value (beta) > and approximately equal 20 deg.), and determined their foreground and background X-ray intensities (relative to the absorbing features), and the respective hardness ratios of that emission. The portion of the sky that was examined to find these shadows was restricted in general to regions where the minimum column density is less than and approximately equal to 4 x 10(exp 20) H/square cm, i.e., relatively high Galactic latitudes, and to regions away from distinct extended features in the SXRB such as supernova remnants and superbubbles. The results for the foreground intensities agree well with the recent results of a general analysis of the local 1/4 KeV emission while the background intensities show additional. but not unexpected scatter. The results also confirm the existence of a gradient in the hardness of the local 1/4 keV emission along a Galactic center/ anticenter axis with a temperature that varies from 10(exp 6.13) K to 10(exp 6.02) K, respectively. The average temperature of the foreground component from this analysis is 10(exp 6.08) K, compared to 10(exp 6.06) K in the previous analysis. Likewise, the average temperature for the distant component for the current and previous analyses are 10(exp 6.06) K and 10(exp 6.02) K, respectively. Finally, the results for the 1/4 keV halo emission are compared to the observed fluxes at 3/4 keV, where the lack of correlation suggests that the Galactic halo's 1/4 keV and 3/4 ke

  10. IC 751: A New Changing Look AGN Discovered by NuSTAR

    NASA Technical Reports Server (NTRS)

    Ricci, C.; Bauer, F. E.; Arevalo, P.; Boggs, S.; Brandt, W. N.; Christensen, F. E.; Craig, W. W.; Ghandi, P.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Markwardt, C. B.; Stern, D.; Treister, E.; Zhang, W. W.

    2016-01-01

    We present results of five Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the type 2 active galactic nucleus (AGN) in IC 751, three of which were performed simultaneously with XMM-Newton or Swift/ X-Ray Telescope. We find that the nuclear X-ray source underwent a clear transition from a Compton-thick (NH approx. = 2 x10(exp 24)/sq cm) to a Compton-thin ( N(sub H) approx. = 4 x10(exp 23)/sq cm) state on timescales of < or approx.3 months, which makes IC 751 the first changing look AGN discovered by NuSTAR. Changes of the line of sight column density at the approx.2 (sigma) level are also found on a timescale of approx. 48 hr (delta N(sub H approx. 10(exp 23)/sq cm). From the lack of spectral variability on timescales of approx.100 ks, we infer that the varying absorber is located beyond the emission-weighted average radius of the broad-line region (BLR), and could therefore be related either to the external part of the BLR or a clumpy molecular torus. By adopting a physical torus X-ray spectral model, we are able to disentangle the column density of the non-varying absorber (N(sub H) approx. 3.8 x10(exp 23)/sq cm) from that of the varying clouds [N(sub H) approx. (1- 150) x 10(exp 22)/sq cm], and to constrain that of the material responsible for the reprocessed X-ray radiation (N(sub H approx. 6 x 10(exp 24)/sq cm).24 -2). We find evidence of significant intrinsic X-ray variability, with the flux varying by a factor of five on timescales of a few months in the 2-10 and 10-50 keV band.

  11. Sequential simulation (SqS) of clinical pathways: a tool for public and patient engagement in point-of-care diagnostics

    PubMed Central

    Huddy, Jeremy R; Weldon, Sharon-Marie; Ralhan, Shvaita; Painter, Tim; Hanna, George B; Kneebone, Roger; Bello, Fernando

    2016-01-01

    Objectives Public and patient engagement (PPE) is fundamental to healthcare research. To facilitate effective engagement in novel point-of-care tests (POCTs), the test and downstream consequences of the result need to be considered. Sequential simulation (SqS) is a tool to represent patient journeys and the effects of intervention at each and subsequent stages. This case study presents a process evaluation of SqS as a tool for PPE in the development of a volatile organic compound-based breath test POCT for the diagnosis of oesophagogastric (OG) cancer. Setting Three 3-hour workshops in central London. Participants 38 members of public attended a workshop, 26 (68%) had no prior experience of the OG cancer diagnostic pathway. Interventions Clinical pathway SqS was developed from a storyboard of a patient, played by an actor, noticing symptoms of oesophageal cancer and following a typical diagnostic pathway. The proposed breath testing strategy was then introduced and incorporated into a second SqS to demonstrate pathway impact. Facilitated group discussions followed each SqS. Primary and secondary outcome measures Evaluation was conducted through pre-event and postevent questionnaires, field notes and analysis of audiovisual recordings. Results 38 participants attended a workshop. All participants agreed they were able to contribute to discussions and like the idea of an OG cancer breath test. Five themes emerged related to the proposed new breath test including awareness of OG cancer, barriers to testing and diagnosis, design of new test device, new clinical pathway and placement of test device. 3 themes emerged related to the use of SqS: participatory engagement, simulation and empathetic engagement, and why participants attended. Conclusions SqS facilitated a shared immersive experience for participants and researchers that led to the coconstruction of knowledge that will guide future research activities and be of value to stakeholders concerned with the invention

  12. Suzaku View of the Neutron Star in the Dipping Source 4U 1822-37

    NASA Technical Reports Server (NTRS)

    Sasano, Makoto; Makishima, Kazuo; Sakurai, Soki; Zhang, Zhongli; Enoto, Teruaki

    2013-01-01

    The dipping X-ray source 4U 1822-37 was observed by Suzaku on 2006 Octrober 20 for a net exposure of 37 ks. The source was detected with the XIS at a 1-10 keV flux of 5.5 ×10(exp -10) erg per square centimeter per second, and with the HXD (HXD-PIN) at a 10-50 keV flux of 8.9 ×10(exp -10) erg per square centimeter per second. With HXD-PIN, the pulsation was detected at a barycentric period of 0.592437 seconds, and its change rate was reconfirmed as -2.43 × 10(exp -12) seconds per second. The 1-50 keV spectra of 4U 1822-37 were found to be very similar to those of Her X- 1 in the slopes, cutoff and iron lines. Three iron lines (Fe Kalpha, Fe XXV, and Fe XXVI) were detected, on top of a 1-50 keV continuum that is described by an NPEX model plus a soft blackbody. In addition, a cyclotron resonance scattering feature was detected significantly ( greater than 99% confidence), at an energy of 33+/-2 keV with a depth of 0.4(sup +0.6)/(sub -0.3). Therefore, the neutron star in this source is concluded to have a strong magnetic field of 2.8 × 10(exp 12) G. Further assuming that the source has a relatively high intrinsic luminosity of several times 10(exp 37) erg per second, its spectral and timing properties are consistently explained.

  13. An antireflection transparent conductor with ultralow optical loss (<2 %) and electrical resistance (<6 Ω sq(-1)).

    PubMed

    Maniyara, Rinu Abraham; Mkhitaryan, Vahagn K; Chen, Tong Lai; Ghosh, Dhriti Sundar; Pruneri, Valerio

    2016-12-19

    Transparent conductors are essential in many optoelectronic devices, such as displays, smart windows, light-emitting diodes and solar cells. Here we demonstrate a transparent conductor with optical loss of ∼1.6%, that is, even lower than that of single-layer graphene (2.3%), and transmission higher than 98% over the visible wavelength range. This was possible by an optimized antireflection design consisting in applying Al-doped ZnO and TiO2 layers with precise thicknesses to a highly conductive Ag ultrathin film. The proposed multilayer structure also possesses a low electrical resistance (5.75 Ω sq(-1)), a figure of merit four times larger than that of indium tin oxide, the most widely used transparent conductor today, and, contrary to it, is mechanically flexible and room temperature deposited. To assess the application potentials, transparent shielding of radiofrequency and microwave interference signals with ∼30 dB attenuation up to 18 GHz was achieved.

  14. Measurement of the cosmic microwave background spectrum by the COBE FIRAS instrument

    NASA Technical Reports Server (NTRS)

    Mather, J. C.; Cheng, E. S.; Cottingham, D. A.; Eplee, R. E., Jr.; Fixsen, D. J.; Hewagama, T.; Isaacman, R. B.; Jensen, K. A.; Meyer, S. S.; Noerdlinger, P. D.

    1994-01-01

    The cosmic microwave background radiation (CMBR) has a blackbody spectrum within 3.4 x 10(exp -8) ergs/sq cm/s/sr cm over the frequency range from 2 to 20/cm (5-0.5 mm). These measurements, derived from the Far-Infrared Absolute Spectrophotomer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite, imply stringent limits on energy release in the early universe after t approximately 1 year and redshift z approximately 3 x 10(exp 6). The deviations are less than 0.30% of the peak brightness, with an rms value of 0.01%, and the dimensionless cosmological distortion parameters are limited to the absolute value of y is less than 2.5 x 10(exp -5) and the absolute value of mu is less than 3.3 x 10(exp -4) (95% confidence level). The temperature of the CMBR is 2.726 +/- 0.010 K (95% confidence level systematic).

  15. Crystal structure and site-directed mutagenesis of 3-ketosteroid Δ1-dehydrogenase from Rhodococcus erythropolis SQ1 explain its catalytic mechanism.

    PubMed

    Rohman, Ali; van Oosterwijk, Niels; Thunnissen, Andy-Mark W H; Dijkstra, Bauke W

    2013-12-06

    3-Ketosteroid Δ(1)-dehydrogenases are FAD-dependent enzymes that catalyze the 1,2-desaturation of 3-ketosteroid substrates to initiate degradation of the steroid nucleus. Here we report the 2.0 Å resolution crystal structure of the 56-kDa enzyme from Rhodococcus erythropolis SQ1 (Δ(1)-KSTD1). The enzyme contains two domains: an FAD-binding domain and a catalytic domain, between which the active site is situated as evidenced by the 2.3 Å resolution structure of Δ(1)-KSTD1 in complex with the reaction product 1,4-androstadiene-3,17-dione. The active site contains four key residues: Tyr(119), Tyr(318), Tyr(487), and Gly(491). Modeling of the substrate 4-androstene-3,17-dione at the position of the product revealed its interactions with these residues and the FAD. The C1 and C2 atoms of the substrate are at reaction distance to the N5 atom of the isoalloxazine ring of FAD and the hydroxyl group of Tyr(318), respectively, whereas the C3 carbonyl group is at hydrogen bonding distance from the hydroxyl group of Tyr(487) and the backbone amide of Gly(491). Site-directed mutagenesis of the tyrosines to phenylalanines confirmed their importance for catalysis. The structural features and the kinetic properties of the mutants suggest a catalytic mechanism in which Tyr(487) and Gly(491) work in tandem to promote keto-enol tautomerization and increase the acidity of the C2 hydrogen atoms of the substrate. With assistance of Tyr(119), the general base Tyr(318) abstracts the axial β-hydrogen from C2 as a proton, whereas the FAD accepts the axial α-hydrogen from the C1 atom of the substrate as a hydride ion.

  16. A search for gamma-ray lines from the decay of Fe-59 in Supernova 1987A

    NASA Technical Reports Server (NTRS)

    Harris, M. J.; Leising, M. D.

    1994-01-01

    We have searched spectra of Supernova (SN) 1987A, accumulated during several 35-day intervals after the explosion by the Solar Maximum Mission (SMM) Gamma Ray Spectrometer (GRS), for gamma-ray lines at 1.099 and 1.292 MeV from the decay of Fe-59 which may have been produced in the progenitor's helium shell. We find no evidence for these lines, down to 3-sigma upper limits approximately = 7 x 10(exp -4) gamma/sq cm/s for the 1.099 MeV line, or approximately = 4.5 x 10(exp -4) gamma/sq cm/s for the 1.292 MeV line, in any 35-day interval. We derive a conservative 3-sigma upper limit on the mass fraction of Fe-59 in the helium shell of 2.9 x 10(exp -3).

  17. Photochemical Modeling of CH3 Abundances in the Outer Solar System

    NASA Technical Reports Server (NTRS)

    Lee, Anthony Y. T.; Yung, Yuk L.; Moses, Julianne

    2000-01-01

    Recent measurements of methyl radicals (CH3) in the upper atmospheres of Saturn and Neptune by the Infrared Space Observatory (ISO) provide new constraints to photochemical models of hydrocarbon chemistry in the outer solar system. The derived column abundances of CH3 on Saturn above 10 mbar and Neptune above the 0.2 mbar pressure level are (2.5 - 6.0) x 10(exp 13) / sq cm and (0.7 - 2.8) x 10(exp 13) / sq cm, respectively. We use the updated Caltech/Jet Propulsion Laboratory photochemical model, which incorporates hydrocarbon photochemistry, vertical molecular and bulk atmospheric eddy diffusion, and realistic radiative transfer modeling, to study the CH3 abundances in the upper atmosphere of the giant planets and Titan. We identify the key reactions that control the concentrations of CH3 in the model, such as the three-body recombination reaction, CH3 + CH3 + M yields C2H6 + M. We evaluate and extrapolate the three-body rate constant of this reaction to the low-temperature limit (1.8 x 10(exp -16) T(sup -3.75) e(sup -300/T), T < 300 K) and compare methyl radical abundances in five atmospheres: Jupiter, Saturn, Uranus, Neptune, and Titan. The sensitivity of our models to the rate coefficients for the reactions H + CH3 + M yields CH4 + M, H + C2H3 yields C2H2 + H2, (sup 1)CH2 + H2 yields CH3 + H, and H + C2H5 yields 2CH3, the branching ratios of CH4 photolysis, vertical mixing in the five atmospheres, and Lyman alpha photon enhancement at the orbit of Neptune have all been tested. The results of our model CH3 abundances for both Saturn (5.1 x 10(exp 13) / sq cm) and Neptune (2.2 x 10(exp 13) / sq cm) show good agreement with ISO Short Wavelength Spectrometer measurements. Using the same chemical reaction set, our calculations also successfully generate vertical profiles of stable hydrocarbons consistent with Voyager and ground-based measurements in these outer solar system atmospheres. Predictions of CH3 column concentrations (for p <= 0.2 mbar) in the atmospheres

  18. The Effect of DRA and SQ3R on the Immediate and Delayed Recall of Seventh-Grade Social Studies Material.

    ERIC Educational Resources Information Center

    Garty, Roberta H.

    The purpose of this study was to examine the effect of the study of organizers, directed reading activity (DRA) and SQ3R, on the immediate and delayed recall of social studies materials. Eighty-four seventh-grade students from an intermediate school participated in this study. The results of the study indicated that the DRA technique was an…

  19. Thromboxane A2 receptor antagonist SQ29548 reduces ischemic stroke-induced microglia/macrophages activation and enrichment, and ameliorates brain injury

    PubMed Central

    Yan, Aijuan; Zhang, Tingting; Yang, Xiao; Shao, Jiaxiang; Fu, Ningzhen; Shen, Fanxia; Fu, Yi; Xia, Weiliang

    2016-01-01

    Thromboxane A2 receptor (TXA2R) activation is thought to be involved in thrombosis/hemostasis and inflammation responses. We have previously shown that TXA2R antagonist SQ29548 attenuates BV2 microglia activation by suppression of ERK pathway, but its effect is not tested in vivo. The present study aims to explore the role of TXA2R on microglia/macrophages activation after ischemia/reperfusion brain injury in mice. Adult male ICR mice underwent 90-min transient middle cerebral artery occlusion (tMCAO). Immediately and 24 h after reperfusion, SQ29548 was administered twice to the ipsilateral ventricle (10 μl, 2.6 μmol/ml, per dose). Cerebral infarction volume, inflammatory cytokines release and microglia/macrophages activation were measured using the cresyl violet method, quantitative polymerase chain reaction (qPCR), and immunofluorescence double staining, respectively. Expression of TXA2R was significantly increased in the ipsilateral brain tissue after ischemia/reperfusion, which was also found to co-localize with activated microglia/macrophages in the infarct area. Administration of SQ29548 inhibited microglia/macrophages activation and enrichment, including both M1 and M2 phenotypes, and attenuated ischemia-induced IL-1ß, IL-6, and TNF-α up-regulation and iNOS release. TXA2R antagonist SQ29548 inhibited ischemia-induced inflammatory response and furthermore reduced microglia/macrophages activation and ischemic/reperfusion brain injury. PMID:27775054

  20. Discovery of X-ray emission associated with the Gum Nebula

    NASA Technical Reports Server (NTRS)

    Leahy, D. A.; Nousek, J.; Garmire, G.

    1992-01-01

    The Gum Nebula was observed by the A-2 LED proportional counters on the HEAO-1 satellite as part of the all-sky survey. The first detection of X-ray emission associated with the Gum Nebula is reported. Soft X-ray spectra were constructed from the A-2 LED PHA data. Single temperature Raymond-Smith models were fitted to the observed spectra to yield temperature, column density and emission measure. The temperature is 6 x 10 exp 5 K, the column density 4 x 10 exp 20/sq cm, and the emission measure 5 cm exp-6 pc. The X-ray and optical properties of the Gum Nebula are consistent with a supernova remnant in the shell stage of evolution, which was the product of an energetic (3 x 10 exp 51 ergs) supernova explosion which occurred about 2 x 10 exp 6 yr ago.

  1. Microbiological characterization of a regenerative life support system

    NASA Technical Reports Server (NTRS)

    Koenig, D. W.; Bruce, R. J.; Mishra, S. K.; Barta, D. J.; Pierson, D. L.

    1994-01-01

    A Variable Pressure Plant Growth Chamber (VPGC), at the Johnson Space Center's (JSC) ground based Regenerative Life Support Systems (RLSS) test bed, was used to produce crops of soil-grown lettuce. The crops and chamber were analyzed for microbiological diversity during lettuce growth and after harvest. Bacterial counts for the rhizosphere, spent nutrient medium, heat exchanger condensate, and atmosphere were approximately 10(exp 11) Colony Forming Units (CFU)/g, 10(exp 5) CFU/ml, 10(exp 5)CFU/ml, and 600 CFU/m sq, repectively. Pseudomonas was the predominant bacterial genus. Numbers of fungi were about 10(exp 5) CFU/g in the rhizosphere, 4-200 CFU/ml in the spent nutient medium, 110 CFU/ml in the heat exchanger condensate, and 3 CFU/cu m in the atmosphere. Fusarium and Trichoderma were the predominant fungal genera.

  2. Performance of transonic fan stage with weight flow per unit annulus area of 208 kilograms per second per square meter (42.6 (lb/sec)/sq ft)

    NASA Technical Reports Server (NTRS)

    Urasek, D. C.; Kovich, G.; Moore, R. D.

    1973-01-01

    Performance was obtained for a 50-cm-diameter compressor designed for a high weight flow per unit annulus area of 208 (kg/sec)/sq m. Peak efficiency values of 0.83 and 0.79 were obtained for the rotor and stage, respectively. The stall margin for the stage was 23 percent, based on equivalent weight flow and total-pressure ratio at peak efficiency and stall.

  3. Electron beam induced damage in PECVD Si3N4 and SiO2 films on InP

    NASA Technical Reports Server (NTRS)

    Pantic, Dragan M.; Kapoor, Vik J.; Young, Paul G.; Williams, Wallace D.; Dickman, John E.

    1990-01-01

    Phosphorus rich plasma enhanced chemical vapor deposition (PECVD) of silicon nitride and silicon dioxide films on n-type indium phosphide (InP) substrates were exposed to electron beam irradiation in the 5 to 40 keV range for the purpose of characterizing the damage induced in the dielectic. The electron beam exposure was on the range of 10(exp -7) to 10(exp -3) C/sq cm. The damage to the devices was characterized by capacitance-voltage (C-V) measurements of the metal insulator semiconductor (MIS) capacitors. These results were compared to results obtained for radiation damage of thermal silicon dioxide on silicon (Si) MOS capacitors with similar exposures. The radiation induced damage in the PECVD silicon nitride films on InP was successfully annealed out in an hydrogen/nitrogen (H2/N2) ambient at 400 C for 15 min. The PECVD silicon dioxide films on InP had the least radiation damage, while the thermal silicon dioxide films on Si had the most radiation damage.

  4. Mutation of the BRCA1 SQ-cluster results in aberrant mitosis, reduced homologous recombination, and a compensatory increase in non-homologous end joining.

    PubMed

    Beckta, Jason M; Dever, Seth M; Gnawali, Nisha; Khalil, Ashraf; Sule, Amrita; Golding, Sarah E; Rosenberg, Elizabeth; Narayanan, Aarthi; Kehn-Hall, Kylene; Xu, Bo; Povirk, Lawrence F; Valerie, Kristoffer

    2015-09-29

    Mutations in the breast cancer susceptibility 1 (BRCA1) gene are catalysts for breast and ovarian cancers. Most mutations are associated with the BRCA1 N- and C-terminal domains linked to DNA double-strand break (DSB) repair. However, little is known about the role of the intervening serine-glutamine (SQ) - cluster in the DNA damage response beyond its importance in regulating cell cycle checkpoints. We show that serine-to-alanine alterations at critical residues within the SQ-cluster known to be phosphorylated by ATM and ATR result in reduced homologous recombination repair (HRR) and aberrant mitosis. While a S1387A BRCA1 mutant - previously shown to abrogate S-phase arrest in response to radiation - resulted in only a modest decrease in HRR, S1387A together with an additional alteration, S1423A (BRCA12P), reduced HRR to vector control levels and similar to a quadruple mutant also including S1457A and S1524A (BRCA14P). These effects appeared to be independent of PALB2. Furthermore, we found that BRCA14P promoted a prolonged and struggling HRR late in the cell cycle and shifted DSB repair from HRR to non-homologous end joining which, in the face of irreparable chromosomal damage, resulted in mitotic catastrophe. Altogether, SQ-cluster phosphorylation is critical for allowing adequate time for completing normal HRR prior to mitosis and preventing cells from entering G1 prematurely resulting in gross chromosomal aberrations.

  5. Mutation of the BRCA1 SQ-cluster results in aberrant mitosis, reduced homologous recombination, and a compensatory increase in non-homologous end joining

    PubMed Central

    Gnawali, Nisha; Khalil, Ashraf; Sule, Amrita; Golding, Sarah E.; Rosenberg, Elizabeth; Narayanan, Aarthi; Kehn-Hall, Kylene; Xu, Bo; Povirk, Lawrence F.; Valerie, Kristoffer

    2015-01-01

    Mutations in the breast cancer susceptibility 1 (BRCA1) gene are catalysts for breast and ovarian cancers. Most mutations are associated with the BRCA1 N- and C-terminal domains linked to DNA double-strand break (DSB) repair. However, little is known about the role of the intervening serine-glutamine (SQ) - cluster in the DNA damage response beyond its importance in regulating cell cycle checkpoints. We show that serine-to-alanine alterations at critical residues within the SQ-cluster known to be phosphorylated by ATM and ATR result in reduced homologous recombination repair (HRR) and aberrant mitosis. While a S1387A BRCA1 mutant - previously shown to abrogate S-phase arrest in response to radiation - resulted in only a modest decrease in HRR, S1387A together with an additional alteration, S1423A (BRCA12P), reduced HRR to vector control levels and similar to a quadruple mutant also including S1457A and S1524A (BRCA14P). These effects appeared to be independent of PALB2. Furthermore, we found that BRCA14P promoted a prolonged and struggling HRR late in the cell cycle and shifted DSB repair from HRR to non-homologous end joining which, in the face of irreparable chromosomal damage, resulted in mitotic catastrophe. Altogether, SQ-cluster phosphorylation is critical for allowing adequate time for completing normal HRR prior to mitosis and preventing cells from entering G1 prematurely resulting in gross chromosomal aberrations. PMID:26320175

  6. Toward 10(exp 9) GPS geodesy: Vector baselines, Earth rotation and reference frames

    NASA Technical Reports Server (NTRS)

    Schutz, Bob E.

    1993-01-01

    The University of Texas Center for Space Research research efforts under NASA Grant No. NAG-1936 from 1 Jan. 1992 - 31 Dec. 1992 were in the following areas: GPS orbit accuracy assessments and efforts to improve the accuracy; analysis of global GPS data collected during the first three months of the IGS campaign, and analysis of regional data. A brief summary of each of the above activities is presented in the following.

  7. Towards 10(exp 9) GPS geodesy: Vector baselines, Earth rotation and reference frames

    NASA Technical Reports Server (NTRS)

    Schutz, Bob E.

    1994-01-01

    Effort during the period form January 1, 1993 to December 31, 1993 were in the following areas: GPS orbit accuracy assessments and efforts to improve the accuracy; analysis and effects of GPS receiver antenna phase center variation; analysis of global GPS data being collected for the IGS campaign; and analysis of regional (south west Pacific) campaign data. A brief summary of each of the above activities is presented.

  8. Photochemistry of Triton's Atmosphere and Ionosphere

    NASA Technical Reports Server (NTRS)

    Krasnopolsky, Vladimir A.; Cruikshank, Dale P.

    1995-01-01

    The photochemistry of 32 neutral and 21 ion species in Triton's atmosphere is considered. Parent species N2, CH4, and CO (with a mixing ratio of 3 x 10(exp -4) in our basic model) sublime from the ice with rates of 40, 208, and 0.3 g/sq cm/b.y., respectively. Chemistry below 50 km is driven mostly by photolysis of methane by the solar and interstellar medium Lyman-alpha photons, producing hydrocarbons C2H4, C2H6, and C2H2 which form haze particles with precipitation rates of 135, 28, and 1.3 g/sq cm/b.y., respectively. Some processes are discussed which increase the production of HCN (by an order of magnitude to a value of 29 g/sq cm/b.y.) and involve indirect photolysis of N2 by neutrals. Reanalysis of the measured methane profiles gives an eddy diffusion coefficient K = 4 x 10(exp 3) sq cm/s above the tropopause and a more accurate methane number density near the surface, (3.1 +/- 0.8) x 10(exp 11)/cc cm. Chemistry above 200 km is driven by the solar EUV radiation (lambda less than 1000 A)) and by precipitation of magnetospheric electrons with a total energy input of 10(exp 8) W (based on thermal balance calculations). The most abundant photochemical species are N, H2, H, O, and C. They escape with the total rates of 7.7 x 10(exp 24)/ s, 4.5 x 10(exp 25)/ s, 2.4 x 10(exp 25)/ s, 4.4 x 10(exp 22)/ s, and 1.1 x 10(exp 24)/ s, respectively. Atomic species are transported to a region of 50-200 km and drive the chemistry there. Iono- spheric chemistry explains the formation of an E region at 150-240 km with HCO(+) as a major ion, and of an F region above 240 km with a peak at 320 km and C(+) as a major ion. The ionosphere above 500 km consists of almost equal densities of C(+) and N(+) ions. The model profiles agree with the measured atomic nitrogen and electron density profiles. A number of other models with varying rate coefficients of some reactions, differing properties of the haze particles (chemically passive or active), etc., were developed. These models show

  9. Recombination of N4(+) ions with electrons

    NASA Technical Reports Server (NTRS)

    Cao, Y. S.; Johnsen, R.

    1991-01-01

    Using a modified high-pressure-afterglow/mass spectrometer apparatus similar to that described by Lee and Johnsen (1989), spectroscopic observations of afterglow helium plasmas, with N2 as a minor additive, were carried out in order to verify the mechanism suggested by Bates (1991) for dissociative recombination of electrons with N4(+) ions. It was found that dissociative recombination of electrons with N4(+) ions results in the formation of N2 molecules in the C 3Pi(u) (v = 0,1) state, with the recombination rate coefficient of (2.6 +/- 0.3) x 10 exp -6 cu cm/sec at 300 K.

  10. Characteristics of long-term variation in the amlitude of the geomagnetic solar quiet (Sq) daily variation using the Inter-university Upper atmosphere Gobal Observation NETwork (IUGONET) data analysis system

    NASA Astrophysics Data System (ADS)

    Shinbori, A.; Koyama, Y.; Nose, M.; Hori, T.; Otsuka, Y.; Yatagai, A. I.

    2014-12-01

    Characteristics of long-term variation in the amplitude of solar quiet geomagnetic field daily variation (Sq) have been investigated using 1-hour geomagnetic field data obtained from 69 geomagnetic stations in a period of 1947-2013. In the present data analysis, we took advantage of the IUGONET data analysis system. The Sq amplitude clearly showed a 10-12 year solar activity dependence and it tended to enhance during each solar maximum. During the minimum of solar cycle 23/24 in 2008-2009, the Sq amplitude became the smallest in the investigated period. The relationship between the solar F10.7 index and Sq amplitude is approximately linear but 64 percent of geomagnetic stations show a weak nonlinear dependence on the solar F10.7 index. In order to remove the effect of solar activity seen in the long-term variation of the Sq amplitude, we calculated a linear or second order fitting curve between the solar F10.7 index and Sq amplitude during 1947-2013, and examined the residual Sq amplitude, which is defined as the deviation from the fitting curve. As a result, a majority of the trends in the residual Sq amplitude that passed through a trend test showed a negative value in a wide region. This tendency was relatively strong in Europe, India, the eastern part of Canada, and New Zealand. The relationship between the magnetic field intensity and residual Sq amplitude showed an anti-correlation for about 71 percent of geomagnetic stations. On the other hand, the residual Sq amplitude in the equatorial station (Addis Ababa) was anti-correlated with the absolute value of the magnetic field inclination. This implies the movement of the equatorial electrojet due to the secular variation of the ambient magnetic field.

  11. The performance of measurement-based simple models for the x-band complex permittivity of 370 ohms/sq. Kapton XC

    SciTech Connect

    Glover, Brian B; Whites, Kieth W; Amert, Tony

    2009-01-01

    The X-band complex permittivity of a commercially-available, carbon loaded, polyamide film is measured. Simple though approximate models are obtained which are shown to be necessary and suitable for analytic or computational modeling of thin absorbing structures realized with the thin lossy film. The utility of each model is tested against experimental results for thin high-impedance surface (HIS) enhanced Salisbury absorbers, enhanced in the sense that the HIS augmented absorber is much thinner than a conventional Salisbury absorber. Kapton XC(reg.) is a commercially-available, carbon-loaded polyamide film manufactured by Dupont(reg.). Though these films are exceptionally durable and available in a range of surface resistivities, their effective permittivity is complex valued and, therefore, their sheet impedance is frequency dependent as is typical of carbon-loaded dielectrics. We have measured the X-band complex permittivity of Kapton XC(reg.) with a manufacture's quoted direct current (DC) sheet resistivity of approximately 370 {Omega}/sq. and thicknesses of 40.0 {mu}m. This study showed the need for relatively precise knowledge of the real part of a carbon particulate loaded, lossy thin film's permittivity in order to accurately engineer the reflection coefficient of high-impedance surface enhanced electromagnetic absorbers. Specifically, simple, approximate models can be obtained for the X-band complex pennittivity of commercially available, carbon loaded, 370 {Omega}/sq., Kapton XC(reg.) thin film. These simple, approximate models can be used in the analytic modeling of high-impedance surface enhanced X-band absorbers or computational modeling of other possibly more complicated absorbing structures which are composed, in part, of 370 {Omega}/sq. Kapton XC(reg.) and designed to operate within the X-band. Finally, the results of this study illustrate the need for simgle models for calculating the complex permittivity spectra of 370 {Omega}/sq. Kapton XC

  12. Photochemistry of Triton's Atmosphere and Ionosphere

    NASA Technical Reports Server (NTRS)

    Krasnopolsky, Vladimir A.; Cruikshank, Dale P.

    1995-01-01

    The photochemistry of 32 neutral and 21 ion species in Triton's atmosphere is considered. Parent species N2, CH4, and CO (with a mixing ratio of 3 x 10(exp -4) in our basic model) sublime from the ice with rates of 40, 208, and 0.3 g/sq cm/b.y., respectively. Chemistry below 50 km is driven mostly by photolysis of methane by the solar and interstellar medium Lyman-alpha photons, producing hydrocarbons C2H4, C2H6, and C2H2 which form haze particles with precipitation rates of 135, 28, and 1.3 g/sq cm/b.y., respectively. Some processes are discussed which increase the production of HCN (by an order of magnitude to a value of 29 g/sq cm/b.y.) and involve indirect photolysis of N2 by neutrals. Reanalysis of the measured methane profiles gives an eddy diffusion coefficient K = 4 x 10(exp 3)sq cm/s above the tropopause and a more accurate methane number density near the surface, (3.1 +/- 0.8)x IO(exp 11)/cu cm. Chemistry above 200 km is driven by the solar EUV radiation (lambda less than 1000 A) and by precipitation of magnetospheric electrons with a total energy input of 10(exp 8) W (based on thermal balance calculations). The most abundant photochemical species are N, H2, H, 0, and C. They escape with the total rates of 7.7 x 10(exp 24)/ s, 4.5 x 10(exp 25)/s, 2.4 x 10(exp 25)/s, 4.4 x 10(exp 22)/s, and 1.1 x 10(exp 24), respectively. Atomic species are transported to a region of 50-200 km and drive the chemistry there. Ionospheric chemistry explains the formation of an E region at 150-240 km with HCO(+) as a major ion, and of an F region above 240 km with a peak at 320 km and C(+) as a major ion. The ionosphere above 500 km consists of almost equal densities of C(+) and N(+) ions. The model profiles agree with the measured atomic nitrogen and electron density profiles. A number of other models with varying rate coefficients of some reactions, differing properties of the haze particles (chemically passive or active), etc., were developed. These models show that there

  13. Hard X-ray Observation of Cygnus X-1 By the Marshall Imaging X-ray Experiment (MIXE2)

    NASA Technical Reports Server (NTRS)

    Minamitani, Takahisa; Apple, J. A.; Austin, R. A.; Dietz, K. L.; Koloziejczak, J. J.; Ramsey, B. D.; Weisskopf, M. C.

    1998-01-01

    The second generation of the Marshall Imaging X-ray Experiment (MIXE2) was flown from Fort Sumner, New Mexico on May 7-8, 1997. The experiment consists of coded-aperture telescope with a field of view of 1.8 degrees (FWHM) and an angular resolution of 6.9 arcminutes. The detector is a large (7.84x10(exp 4) sq cm) effective area microstrip proportional counter filled with 2.0x10(exp5) Pascals of xenon with 2% isobutylene. We present MIXE2 observation of the 20-80keV spectrum and timing variability of Cygnus X-1 made during balloon flight.

  14. Thermodynamic properties and theoretical rocket performance of hydrogen to 100,000 K and 1.01325 x 10 to the 8th power N/sq m

    NASA Technical Reports Server (NTRS)

    Patch, R. W.

    1971-01-01

    The composition and thermodynamic properties were calculated for 100 to 110,000 K and 1.01325 x 10 to the 2nd power to 1.01325 x 10 to the 8th power N/sq m for chemical equilibrium in the Debye-Huckel and ideal-gas approximations. Quantities obtained were the concentrations of hydrogen atoms, protons, free electrons, hydrogen molecules, negative hydrogen ions, hydrogen diatomic molecular ions, and hydrogen triatomic molecular ions, and the enthalpy, entropy, average molecular weight, specific heat at constant pressure, density, and isentropic exponent. Electronically excited states of H and H2 were included. Choked, isentropic, one-dimensional nozzle flow with shifting chemical equilibrium was calculated to the Debye-Huckel and ideal-gas approximations for stagnation temperatures from 2500 to 100,000 K. The mass flow per unit throat area and the sonic flow factor were obtained. The pressure ratio, temperature, velocity, and ideal and vacuum specific impulses at the throat and for pressure ratios as low as 0.000001 downstream were found. For high temperatures at pressures approaching 1.01325 x 10 to the 8th power N/sq m, the ideal-gas approximation was found to be inadequate for calculations of composition, precise thermodynamic properties, and precise nozzle flow. The greatest discrepancy in nozzle flow occurred in the exit temperature, which was as much as 21 percent higher when the Debye-Huckel approximation was used.

  15. Low-Temperature Rate Coefficients of C2H with CH4 and CD4 from 154 to 359 K

    NASA Technical Reports Server (NTRS)

    Opansky, Brian J.; Leone, Stephen R.

    1996-01-01

    Rate coefficients for the reaction C2H + CH4 yields C2H2 + CH3 and C2H + CD4 yields C2HD + CD3 are measured over the temperature range 154-359 K using transient infrared laser absorption spectroscopy. Ethynyl radicals are produced by pulsed laser photolysis of C2H2 in a variable temperature flow cell, and a tunable color center laser probes the transient removal of C2H (Chi(exp 2) Sigma(+) (0,0,0)) in absorption. The rate coefficients for the reactions of C2H with CH4 and CD4 both show a positive temperature dependence over the range 154-359 K, which can be expressed as k(sub CH4) = (1.2 +/- 0.1) x 10(exp -11) exp((-491 +/- 12)/T) and k(sub CD4) = (8.7 +/- 1.8) x 10(exp -12) exp((-650 +/- 61)/T) cm(exp 3) molecule(exp -1) s(exp -1), respectively. The reaction of C2H + CH4 exhibits a significant kinetic isotope effect at 300 K of k(sub CH4)/k(sub CD4) = 2.5 +/- 0.2. Temperature dependent rate constants for C2H + C2H2 were also remeasured over an increased temperature range from 143 to 359 K and found to show a slight negative temperature dependence, which can be expressed as k(sub C2H2) = 8.6 x 10(exp -16) T(exp 1.8) exp((474 +/- 90)/T) cm(exp 3) molecule(exp -1) s(exp -1).

  16. High Silicate Crystalline-to-Amorphous Ratios in Comets C/2001 Q4 (NEAT) and Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Wooden, D. H.; Harker, D. E.; Woodward, C. E.

    2004-01-01

    Crystalline silicates, by their apparent absence in the ISM, are dust grains that experienced high temperatures in the solar nebula. Mg-rich crystalline silicates formed either by condensation from hot nebular gases (1450 K) or by the annealing of Mg-rich amorphous silicates (approx. 1000 K) in shocks in the 5-10 AU region or by radial transport into and out of the hot inner zones, e.g., T(sub d) > 1000 K at r(sub h) < 5 AU, 10(exp -6) - 10(exp -5) M(sub O)/yr, alpha = 10(exp -4) of the early solar nebula. Mg-rich crystalline silicates are found in interplanetary dust particles (IDPs) and produce IR spectral features in many Oort cloud comets. In May 2004, we discovered strong crystalline silicate features in the dynamically new Oort cloud comet C/2001 Q4 (NEAT). Thermal emission modeling of comets Q4 and C/1995 O1 (Hale-Bopp) demonstrate that both these comets have similar, high silicate crystalline-to-amorphous ratios of 2.4 and 2.1, respectively, indicating that these icy planetesimals aggregated from similar reservoirs of material or that crystalline silicates were widely distributed within the comet-forming zone. This argues for efficient annealing mechanisms and radial mixing.

  17. High Silicate Crystalline-to-Amorphous Ratios in Comets C/2001 Q4 (NEAT) and Hale-Bopp

    NASA Technical Reports Server (NTRS)

    Wooden, D. H.; Harker, D. E.; Wodward, C. E.

    2004-01-01

    Crystalline silicates, by their apparent absence in the ISM, are dust grains that experienced high temperatures in the solar nebula. Mg-rich crystalline silicates formed either by condensation from hot nebular gases (1450 K) or by the annealing of Mg-rich amorphous silicates (approximately 1000 K) in shocks in the 5-10AU region or by radial transport into and out of the hot inner zones, e.g., T(sub d) greater than 1000K at r(sub h) less than 5AU, 10(exp -6) -10(exp -5) solar mass per year, alpha = 10(exp -4) of the early solar nebula. Mg-rich crystalline silicates are found in interplanetary dust particles (IDPs) and produce IR spectral features in many Oort cloud comets. In May 2004, we discovered strong crystalline silicate features in the dynamically new Oort cloud comet C/2001 Q4 (NEAT). Thermal emission modeling of comets Q4 and C/1995 O1 (Hale-Bopp) demonstrate that both these comets have similar, high silicate crystalline-toamorphous ratios of 2.4 and 2.1, respectively, indicating that these icy planetesimals aggregated from similar reservoirs of material or that crystalline silicates were widely distributed within the comet-forming zone. This argues for efficient annealing mechanisms and radial mixing.

  18. A galaxy with a 3.2 X 2.2 sq KPC H II region surrounding its nucleus

    NASA Astrophysics Data System (ADS)

    Meaburn, J.

    1983-06-01

    The spiral galaxy MCG-05-32-052 has a supergiant H II region surrounding its nucleus. The outer regions of this galaxy are in circular motion at ≅115 km s-1 but non-circular motions over a range of 100 km s-1 are found around the nucleus. Brightness ratios of the optical emission lines indicate that radiative ionization is predominant and a rate of emission of Lyman photons in the range 0.4 to 1.3×1053 s-1 is required to produce the total Hα intensity. A total ionized mass in the range 1.3 to 4×107 M_sun; is calculated and the total stellar mass in the central regions out to a radius of 1450 pc is given as 2.4×109 M_sun;. Three sources for this ionization and large motions are considered: either rich clusters of numerous ordinary OB stars with stellar winds and recurrent supernova explosions or one or several supermassive stars like the central object R 136a inside the 30 Dor nebula.

  19. Observation of a Long-Term Spin-up Trend in 4U 1538-52

    NASA Technical Reports Server (NTRS)

    Rubin, B. C.; Finger, M. H.; Scott, D. M.; Wilson, R. B.

    1997-01-01

    The high-mass X-ray pulsar 4U 153 8-52 has been continually monitored by the Burst and Transient Source Experiment (BATSE) on Compton Gamma-Ray Observatory. These observations permit the construction of long-term pulse frequency and intensity histories. The frequency history reveals that a reversal of the long-term trend in the accretion torque, from spinning down to spinning up, has occurred, probably in 1988. This is the first time a long-term change is known to have occurred for this source, The magnitude of the average absolute value of (dot-nu / nu) is approximately 10(exp -11)/s over an interval of approximately 5 year is similar during spin-down and spin-up. Shorter term pulse frequency variations of either sign are also observed. The power density spectrum of fluctuations in angular acceleration is consistent with white noise on timescales from 16 to 1600 days. It can be well fit with a power law with a power-law index of 0.10 plus or minus 0.21 and white noise strength of (7.6 +/- 1.6) x 10(exp -21) (Hz/s(exp 2)/Hz). These observations are also used to set 95% confidence level lower and upper limits on the rate of orbital period change, -3.9< dot-P orb /P orb <2. 1, in units of 10(exp -6) yr(exp -1).

  20. Anomalous Variability in Antarctic Sea Ice Extents During the 1960s With the Use of Nimbus Data

    NASA Technical Reports Server (NTRS)

    Gallaher, David W.; Campbell, G. Garrett; Meier, Walter N.

    2013-01-01

    The Nimbus I, II, and III satellites provide a new opportunity for climate studies in the 1960s. The rescue of the visible and infrared imager data resulted in the utilization of the early Nimbus data to determine sea ice extent. A qualitative analysis of the early NASA Nimbus missions has revealed Antarctic sea ice extents that are significant larger and smaller than the historic 1979-2012 passive microwave record. The September 1964 ice mean area is 19.7x10(exp 6) sq. km +/- 0.3x10(exp 6) sq. km. This is more the 250,000 sq. km greater than the 19.44x10(exp 6) sq. km seen in the new 2012 historic maximum. However, in August 1966 the maximum sea ice extent fell to 15.9x10(exp 6) sq. km +/- 0.3x10(exp 6) sq. km. This is more than 1.5x10(exp 6) sq. km below the passive microwave record of 17.5x10(exp 6) sq. km set in September of 1986. This variation between 1964 and 1966 represents a change of maximum sea ice of over 3x10(exp 6) sq. km in just two years. These inter-annual variations while large, are small when compared to the Antarctic seasonal cycle.

  1. Evaluation of an analytical methodology using QuEChERS and GC-SQ/MS for the investigation of the level of pesticide residues in Brazilian melons.

    PubMed

    da Silva Sousa, Jonas; de Castro, Rubens Carius; de Albuquerque Andrade, Gilliane; Lima, Cleidiane Gomes; Lima, Lucélia Kátia; Milhome, Maria Aparecida Liberato; do Nascimento, Ronaldo Ferreira

    2013-12-01

    A multiresidue method based on the sample preparation by modified QuEChERS and detection by gas chromatography coupled to single quadruple mass spectrometers (GC-SQ/MS) was used for the analysis of 35 multiclass pesticides in melons (Cucumis melo inodorus) produced in Ceara-Brazil. The rates of recovery for pesticides studied were satisfactory (except for the etridiazole), ranging from 85% to 117% with a relative standard deviation (RSD) of less than 15%, at concentrations between 0.05 and 0.20 mg kg(-1). The limit of quantification (LOQ) for most compounds was below the MRLs established in Brazil. The combined relative uncertainty (Uc) and expanded uncertainty (Ue) was determined using repeatability, recovery and calibration curves data for each pesticide. Analysis of commercial melons samples revealed the presence of pesticides bifenthrin and imazalil at levels below the MRLs established by ANVISA, EU and USEPA.

  2. Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

    NASA Technical Reports Server (NTRS)

    Vered, R.; Grossman, E.; Lempert, G. D.; Lifshitz, Y.

    1994-01-01

    A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

  3. Atomic Oxygen (ATOX) simulation of Teflon FEP and Kapton H surfaces using a high intensity, low energy, mass selected, ion beam facility

    NASA Astrophysics Data System (ADS)

    Vered, R.; Grossman, E.; Lempert, G. D.; Lifshitz, Y.

    1994-11-01

    A high intensity (greater than 10(exp 15) ions/sq cm) low energy (down to 5 eV) mass selected ion beam (MSIB) facility was used to study the effects of ATOX on two polymers commonly used for space applications (Kapton H and Teflon FEP). The polymers were exposed to O(+) and Ne(+) fluences on 10(exp 15) - 10(exp 19) ions/sq cm, using 30eV ions. A variety of analytical methods were used to analyze the eroded surfaces including: (1) atomic force microscopy (AFM) for morphology measurements; (2) total mass loss measurements using a microbalance; (3) surface chemical composition using x-ray photoelectron spectroscopy (XPS), and (4) residual gas analysis (RGA) of the released gases during bombardment. The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of Ne(+) and O(+) bombardment. For 30 eV ions it was found that the Kapton is eroded via chemical mechanisms while Teflon FEP is eroded via collisional mechanisms. AFM analysis was found very powerful in revealing the evolution of the damage from its initial atomic scale (roughness of approx. 1 nm) to its final microscopic scale (roughness greater than 1 micron). Both the surface morphology and the average roughness of the bombarded surfaces (averaged over 1 micron x 1 micron images by the system's computer) were determined for each sample. For 30 eV a non linear increase of the Kapton roughness with the O(+) fluence was discovered (a slow increase rate for fluences phi less than 5 x 10(exp 17) O(+)/sq cm, and a rapid increase rate for phi greater than 5 x 10(exp 17) O(+)/sq cm). Comparative studies on the same materials exposed to RF and DC oxygen plasmas indicate that the specific details of the erosion depend on the simulation facility emphasizing the advantages of the ion beam facility.

  4. Experimental Investigation of the Heat-Transfer Rate to a Series of 20 deg Cones of Various Surface Finishes at a Mach Number of 4.95

    NASA Technical Reports Server (NTRS)

    Jones, Jim J.

    1959-01-01

    The heat-transfer rates were measured on a series of cones of various surface finishes at a Mach number of 4.95 and Reynolds numbers per foot varying from 20 x 10(exp 6) to 100 x 10(exp 6). The range of surface finish was from a very smooth polish to smooth machining with no polish (65 micro inches rms). Some laminar boundary-layer data were obtained, since transition was not artificially tripped. Emphasis, however, is centered on the turbulent boundary layer. The results indicated that the turbulent heat-transfer rate for the highest roughness tested was only slightly greater than that for the smoothest surface. The laminar-sublayer thickness was calculated to be about half the roughness height for the roughest model at the highest value of unit Reynolds number tested.

  5. CARS: the CFHTLS-Archive-Research Survey. I. Five-band multi-colour data from 37 sq. deg. CFHTLS-wide observations

    NASA Astrophysics Data System (ADS)

    Erben, T.; Hildebrandt, H.; Lerchster, M.; Hudelot, P.; Benjamin, J.; van Waerbeke, L.; Schrabback, T.; Brimioulle, F.; Cordes, O.; Dietrich, J. P.; Holhjem, K.; Schirmer, M.; Schneider, P.

    2009-01-01

    Context: We present the CFHTLS-Archive-Research Survey (CARS). It is a virtual multi-colour survey that is based on public archive images from the Deep and Wide components of the CFHT-Legacy-Survey (CFHTLS). Our main scientific interests in the CFHTLS Wide-part of CARS are optical searches for galaxy clusters from low to high redshift and their subsequent study with photometric and weak-gravitational lensing techniques. Aims: As a first step in the CARS project, we present multi-colour catalogues from 37 sq. degrees of the CFHTLS-Wide component. Our aims are first to create astrometrically and photometrically well-calibrated co-added images from publicly available CFHTLS data. Second, we offer five-band (u^*g'r'i'z') multi-band catalogues with an emphasis on reliable estimates for object colours. These are subsequently used for photometric redshift estimates. Methods: We consider all those CFHTLS-Wide survey pointings that were publicly available on January 2008 and that also have five-band coverage in u^*g'r'i'z'. The data were calibrated and processed with our GaBoDS/THELI image processing pipeline. The quality of the resulting images was thoroughly checked against the Sloan-Digital-Sky Survey (SDSS) and already public high-end CFHTLS data products. From the co-added images we extracted source catalogues and determined photometric redshifts using the public code Bayesian Photometric Redshifts (BPZ). Fifteen of our survey fields directly overlap with public spectra from the VIMOS VLT deep (VVDS), DEEP2 and SDSS redshift surveys, which we used for calibration and verification of our redshift estimates. Furthermore we applied a novel technique, based on studies of the angular galaxy cross-correlation function, to quantify the reliability of photo-z's. Results: With this paper we present 37 sq. degrees of homogeneous and high-quality five-colour photometric data from the CFHTLS-Wide survey. The median seeing of our data is better than 0.9 arcsec in all bands and our

  6. Alpha-2 Heremans Schmid Glycoprotein (AHSG) Modulates Signaling Pathways in Head and Neck Squamous Cell Carcinoma Cell Line SQ20B

    SciTech Connect

    Thompson, Pamela D.; Sakwe, Amos; Koumangoye, Rainelli; Yarbrough, Wendell G.; Ochieng, Josiah; Marshall, Dana R.

    2014-02-15

    This study was performed to identify the potential role of Alpha-2 Heremans Schmid Glycoprotein (AHSG) in Head and Neck Squamous Cell Carcinoma (HNSCC) tumorigenesis using an HNSCC cell line model. HNSCC cell lines are unique among cancer cell lines, in that they produce endogenous AHSG and do not rely, solely, on AHSG derived from serum. To produce our model, we performed a stable transfection to down-regulate AHSG in the HNSCC cell line SQ20B, resulting in three SQ20B sublines, AH50 with 50% AHSG production, AH20 with 20% AHSG production and EV which is the empty vector control expressing wild-type levels of AHSG. Utilizing these sublines, we examined the effect of AHSG depletion on cellular adhesion, proliferation, migration and invasion in a serum-free environment. We demonstrated that sublines EV and AH50 adhered to plastic and laminin significantly faster than the AH20 cell line, supporting the previously reported role of exogenous AHSG in cell adhesion. As for proliferative potential, EV had the greatest amount of proliferation with AH50 proliferation significantly diminished. AH20 cells did not proliferate at all. Depletion of AHSG also diminished cellular migration and invasion. TGF-β was examined to determine whether levels of the TGF-β binding AHSG influenced the effect of TGF-β on cell signaling and proliferation. Whereas higher levels of AHSG blunted TGF-β influenced SMAD and ERK signaling, it did not clearly affect proliferation, suggesting that AHSG influences on adhesion, proliferation, invasion and migration are primarily due to its role in adhesion and cell spreading. The previously reported role of AHSG in potentiating metastasis via protecting MMP-9 from autolysis was also supported in this cell line based model system of endogenous AHSG production in HNSCC. Together, these data show that endogenously produced AHSG in an HNSCC cell line, promotes in vitro cellular properties identified as having a role in tumorigenesis. Highlights: • Head

  7. CN and HCN in the infrared spectrum of IRC + 10216

    NASA Technical Reports Server (NTRS)

    Wiedemann, G. R.; Deming, D.; Jennings, D. E.; Hinkle, Kenneth H.; Keady, John J.

    1991-01-01

    The abundance of HCN in the inner circumstellar shell of IRC + 10216 has been remeasured using the 12-micron nu2 band. The 12-micron lines are less saturated than HCN 3-micron lines previously detected in the spectrum of IRC + 10216. The observed 12-micron HCN line is formed in the circumstellar shell from about 4 to 12 R sub * in accord with a photospheric origin for HCN. The derived HCN abundance in the 4 to 12 R sub* region is 4 x 10 exp-5 and the column density is 7 x 10 exp 18/sq cm. The 5-micron CN vibration-rotation fundamental band was detected for the first time in an astronomical source. Using four CN lines, the CN column density was determined to be 2.6 x 10 exp 15/sq cm and the rotational temperature to be 8 +/-2 K. The peal radial abundance is 1 x 10 exp -5. The values for the temperature and abundance are in good agreement with microwave results and with the formation of CN from the photolysis of HCN.

  8. CN and HCN in the infrared spectrum of IRC + 10216

    NASA Astrophysics Data System (ADS)

    Wiedemann, G. R.; Deming, D.; Jennings, D. E.; Hinkle, Kenneth H.; Keady, John J.

    1991-11-01

    The abundance of HCN in the inner circumstellar shell of IRC + 10216 has been remeasured using the 12-micron nu2 band. The 12-micron lines are less saturated than HCN 3-micron lines previously detected in the spectrum of IRC + 10216. The observed 12-micron HCN line is formed in the circumstellar shell from about 4 to 12 R* in accord with a photospheric origin for HCN. The derived HCN abundance in the 4 to 12 R sub* region is 4 x 10 exp-5 and the column density is 7 x 10 exp 18/sq cm. The 5-micron CN vibration-rotation fundamental band was detected for the first time in an astronomical source. Using four CN lines, the CN column density was determined to be 2.6 x 10 exp 15/sq cm and the rotational temperature to be 8 +/-2 K. The peal radial abundance is 1 x 10 exp -5. The values for the temperature and abundance are in good agreement with microwave results and with the formation of CN from the photolysis of HCN.

  9. Long-term survival of bacterial spores in space

    NASA Technical Reports Server (NTRS)

    Horneck, G.; Bucker, H.; Reitz, G.

    1994-01-01

    On board of the NASA Long Duration Exposure Facility (LDEF), spores of Bacillus subtilis in monolayers (10(exp 6)/sample) or multilayers (10(exp 8)/sample) were exposed to the space environment for nearly six years and their survival was analyzed after retrieval. The response to space parameters, such as vacuum (10(exp -6) Pa), solar electromagnetic radiation up to the highly energetic vacuum-ultraviolet range 10(exp 9) J/sq m) and/or cosmic radiation (4.8 Gy), was studied and compared to the results of a simultaneously running ground control experiment. If shielded against solar ultraviolet (UV)-radiation, up to 80% of spores in multilayers survive in space. Solar UV-radiation, being the most deleterious parameter of space, reduces survival by 4 orders of magnitude or more. However, up to 10(exp 4) viable spores were still recovered, even in completely unprotected samples. Substances, such as glucose or buffer salts serve as chemical protectants. With this 6 year study in space, experimental data are provided to the discussion on the likelihood of 'Panspermia'.

  10. Measuring IPDE-SQ personality disorder prevalence in pre-sentence and early-stage prison populations, with sub-type estimates.

    PubMed

    Slade, Karen; Forrester, Andrew

    2013-01-01

    Understanding the prevalence and type of personality disorder within prison systems allows for the effective targeting of resources to implement strategies to alleviate symptoms, manage behaviour and attempt to reduce re-offending. This study aimed to determine the prevalence of personality disorder (PD) traits within a local urban high-turnover adult male prison with a remand/recently sentenced population in London, UK. The International Personality Disorder Examination - Screening Questionnaire (IPDE-SQ) self-administered questionnaire (ICD-10 version) was completed by 283 prisoners (42% completion rate). 77% of respondents reached the threshold for one or more PDs. The most common PD types were Paranoid PD (44.5%), Anankastic PD (40.3%), Schizoid PD (35%) and Dissocial PD (25.8%). These results confirm and extend existing knowledge regarding the prevalence of PD in prison populations into a high-turnover, urban, remand population. The stark comparison with community samples indicates that a more equitable standard of service delivery within the criminal justice system, focussing on preventive and early intervention services, is now required.

  11. SWIFT BAT Survey of AGN

    NASA Technical Reports Server (NTRS)

    Tueller, J.; Mushotzky, R. F.; Barthelmy, S.; Cannizzo, J. K.; Gehrels, N.; Markwardt, C. B.; Skinner, G. K.; Winter, L. M.

    2008-01-01

    We present the results1 of the analysis of the first 9 months of data of the Swift BAT survey of AGN in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGN) of 130 objects detected at [b] > 15deg and with significance > 4.8-delta. One source remains unidentified. These same X-ray data have allowed measurement of the X-ray properties of the objects. We fit a power law to the logN - log S distribution, and find the slope to be 1.42+/-0.14. Characterizing the differential luminosity function data as a broken power law, we find a break luminosity logL*(ergs/s)= 43.85+/-0.26. We obtain a mean photon index 1.98 in the 14-195 keV band, with an rms spread of 0.27. Integration of our luminosity function gives a local volume density of AGN above 10(exp 41) erg/s of 2.4x10(exp -3) Mpc(sup -3), which is about 10% of the total luminous local galaxy density above M* = -19.75. We have obtained X-ray spectra from the literature and from Swift XRT follow-up observations. These show that the distribution of log nH is essentially flat from nH = 10(exp 20)/sq cm to 10(exp 24)/sq cm, with 50% of the objects having column densities of less than 10(exp 22)/sq cm. BAT Seyfert galaxies have a median redshift of 0.03, a maximum log luminosity of 45.1, and approximately half have log nH > 22.

  12. Optimal and Local Connectivity Between Neuron and Synapse Array in the Quantum Dot/Silicon Brain

    NASA Technical Reports Server (NTRS)

    Duong, Tuan A.; Assad, Christopher; Thakoor, Anikumar P.

    2010-01-01

    This innovation is used to connect between synapse and neuron arrays using nanowire in quantum dot and metal in CMOS (complementary metal oxide semiconductor) technology to enable the density of a brain-like connection in hardware. The hardware implementation combines three technologies: 1. Quantum dot and nanowire-based compact synaptic cell (50x50 sq nm) with inherently low parasitic capacitance (hence, low dynamic power approx.l0(exp -11) watts/synapse), 2. Neuron and learning circuits implemented in 50-nm CMOS technology, to be integrated with quantum dot and nanowire synapse, and 3. 3D stacking approach to achieve the overall numbers of high density O(10(exp 12)) synapses and O(10(exp 8)) neurons in the overall system. In a 1-sq cm of quantum dot layer sitting on a 50-nm CMOS layer, innovators were able to pack a 10(exp 6)-neuron and 10(exp 10)-synapse array; however, the constraint for the connection scheme is that each neuron will receive a non-identical 10(exp 4)-synapse set, including itself, via its efficacy of the connection. This is not a fully connected system where the 100x100 synapse array only has a 100-input data bus and 100-output data bus. Due to the data bus sharing, it poses a great challenge to have a complete connected system, and its constraint within the quantum dot and silicon wafer layer. For an effective connection scheme, there are three conditions to be met: 1. Local connection. 2. The nanowire should be connected locally, not globally from which it helps to maximize the data flow by sharing the same wire space location. 3. Each synapse can have an alternate summation line if needed (this option is doable based on the simple mask creation). The 10(exp 3)x10(exp 3)-neuron array was partitioned into a 10-block, 10(exp 2)x10(exp 3)-neuron array. This building block can be completely mapped within itself (10,000 synapses to a neuron).

  13. Expectations for X-ray cluster observations by the Rosat satellite

    NASA Technical Reports Server (NTRS)

    Evrard, A. E.; Henry, J. P.

    1991-01-01

    Predictions for characteristics of the X-ray cluster population expected to be observed by the Rosat satellite are presented via theoretical models for the evolution of X-ray cluster abundances. With a square detect cell of side 4.8 arcmin employed to search for extended cluster sources, roughly 200 clusters per steradian above the all-sky survey limiting flux of 7 x 10 exp -13 ergs/s sq cm are expected. For the north ecliptic pole region of the Rosat survey, which is to cover a 10-deg radius field to a limiting flux of roughly 9 x 10 exp -14 ergs/s sq cm, about 330 cluster X-ray sources are predicted. The clusters should have a median redshift of 0.2, and 10 percent of them should have z greater than 0.4.

  14. OSSE observations of galactic 511 keV annihilation radiation

    NASA Technical Reports Server (NTRS)

    Purcell, W. R.; Grabelsky, D. A.; Johnson, W. N.; Jung, G. V.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Ulmer, M. P.

    1992-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory has performed several observations of the galactic plane and galactic center region to measure the distribution of galactic 511 keV positron annihilation radiation. Preliminary analysis of data collected during the observation of the galactic center region over the period 13-24 Jun. 1991, indicates the presence of a 511 keV line and positronium continuum superimposed on a power-law continuum. The line of flux was found to be (2.7 +/- 0.5) x 10(exp -4) gamma/sq cm sec, with a positronium fraction of (0.9 +/- 0.2). The 3(sigma) upper limit to daily variations in the 511 keV line flux from the mean during the observation interval is 3 x 10(exp -4) gamma/sq cm sec. If all of the observed annihilation radiation is assumed to originate from the x-ray source 1E 1740.7-2942, the corresponding 511 keV line flux would be (3.0 +/- 0.6) x 10(exp -4) gamma/sq cm sec. The 3(sigma) upper limit for 511 keV line emission from the x-ray binary GX1+4 is 6 x 10(exp -4) gamma/sq cm sec. Results from the galactic plane observations at galactic longitudes of 25 degrees (16-21 Aug. 1991) and 339 degrees (6-11 Sep. 1991) suggest that the emission is concentrated near the galactic center. The observations and the preliminary results are described.

  15. FUSE Observations of O VI Absorption in the Local Interstellar Medium

    NASA Technical Reports Server (NTRS)

    Oegerle, W. R.; Jenkins, E. B.; Shelton, R. L.; Bowen, D. V.; Fisher, Richard R. (Technical Monitor)

    2000-01-01

    We report the results of an initial Far Ultraviolet Spectroscopic Explorer (FUSE) survey of O VI Lambda 1032 absorption along the lines of sight to eleven nearby white dwarfs, ten of which are within the Local Bubble (LB; d < or approximately equal 100 pc). A goal of this survey is to investigate the possible formation of O VI in the conductive interfaces between cool (about 10(exp 4) K) clouds immersed in the presumably hot (10(exp 6) K) gas within the LB. This mechanism is often invoked to explain the widespread presence of 0 VI throughout the Galactic disk. We find no 0 VI absorption toward two stars, and the column densities along three additional sight lines are quite low; N(O VI) about 5 x 10(exp 13)/sq cm. In several directions, we observe rather broad, shallow absorption with N(O VI) about 1 - 2 x 10(exp 13)/sq cm. Models of conductive interfaces predict narrow profiles with N(OVI) > or about equal to 10(exp 13)/sq cm per interface, in the absence of a significant transverse magnetic field. Hence, our observations of weak 0 VI absorption indicate that conduction is being quenched, possibly by non-radial magnetic fields. Alternatively, the gas within the LB may not be hot. Breitschwerdt & Schmutzler have proposed a model for the LB in which an explosive event within a dense cloud created rapid expansion and adiabatic cooling, resulting in a cavity containing gas with a kinetic temperature of T about 50,000 K, but with an ionization state characteristic of much hotter gas. This model has a number of attractive features, but appears to predict significantly more O VI than we observe.

  16. Modeling of pickup ion distributions in the Halley cometosheath: Empirical limits on rates of ionization, diffusion, loss and creation of fast neutral atoms

    NASA Technical Reports Server (NTRS)

    Huddleston, D. E.; Neugebauer, M.; Goldstein, B. E.

    1994-01-01

    The shape of the velocity distribution of water group ions observed by the Giotto ion mass spectrometer on its approach to comet Halley is modeled to derive empirical values for the rates of ionization, energy diffusion, and loss in the midcometosheath. The model includes the effect of rapid pitch angle scattering into a bispherical shell distribution as well as the effect of the magnetization of the plasma on the charge exchange loss rate. It is found that the average rate of ionization of cometary neutrals in this region of the cometosheath appears to be of the order of a factor 3 faster than the `standard' rates approx. 1 x 10(exp -6)/s that are generally assumed to model the observations in most regions of the comet environment. For the region of the coma studied in the present work (approx. 1 - 2 x 10(exp 5) km from the nucleus), the inferred energy diffusion coefficient is D(sub 0) approx. equals 0.0002 to 0.0005 sq km/cu s, which is generally lower than values used in other models. The empirically obtained loss rate appears to be about an order of magnitude greater than can be explained by charge exchange with the `standard' cross section of approx. 2 x 10(exp -15)sq cm. However such cross sections are not well known and for water group ion/water group neutral interactions, rates as high as 8 x 10(exp -15) sq cm have previously been suggested in the literature. Assuming the entire loss rate is due to charge exchange yields a rate of creation of fast neutral atoms of the order of approx. 10(exp -4)/s or higher, depending on the level of velocity diffusion. The fast neutrals may, in turn, be partly responsible for the higher-than-expected ionization rate.

  17. Constraints on the cosmic rays in the Small Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Sreekumar, P.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

    1993-01-01

    Observations of the SMC using the Energetic Gamma Ray Experimental Telescope (EGRET) on the Compton Observatory are reported. The findings yield an upper limit for gamma-ray emission above 100 MeV of 0.5 x 10 exp -7 photon/sq cm s. The expected flux if the cosmic rays (CR) are universal rather than Galactic in origin is (2.4 +/- 0.5) x 10 exp -7 photon/sq cm s, only a third of which arises from cosmic ray electron interactions. Thus, the bulk of the CR energy density is almost certainly neither metagalactic nor universal, but Galactic in origin. The results add to the evidence that the SMC is in a nonequilibrium state and indicate that the LMC is most likely in quasi-stable equilibrium, with a CR energy density near the maximum that can be contained.

  18. The Properties and Effects of Titan's Organic Haze

    NASA Technical Reports Server (NTRS)

    McKay, Christopher P.; Young, Richard E. (Technical Monitor)

    1997-01-01

    Titan's organic haze is the the dominant absorber of solar energy in Titan's atmosphere, creating an anti-greenhouse effect. Its variation over time may have had important implications for Titan's surface temperature. The haze is potentially an important sink of photochemically produced carbon and nitrogen compounds. Laboratory simulations and microphysical models suggest that the haze is a sink for C of 4 x 10(exp 8)/ sq cm s, and a sink for N of 1 x 10(exp 8)sq cm s. The C sink is small compared to condensation of hydrocarbons but the sink for N is comparable to the total production rate of HCN. Because estimates of the eddy diffusion profile on Titan have been based on the HCN profile, inclusion of this additional sink for N will affect estimates for all transport processes in Titan's atmosphere.

  19. Correlation between fabrication factor and superconducting properties of the Tl-and-Bi-based high-Tc superconductor

    NASA Technical Reports Server (NTRS)

    Maki, Naoki; Okada, Michiya; Doi, Toshiya J.; Kanai, Tsuneyuki; Sato, Junichi; Higashiyama, Kazutoshi

    1995-01-01

    Large critical current densities (J(sub c)) were obtained in c axis oriented Tl-1 223/Ag composite tapes fabricated by spraying methods without a vacuum. Transport measurements at 77K under a zero field indicated a J(sub c) of 9 x 10(exp 4) A/sq cm and 7 x 10(exp 3) A/sq cm at 1T for the tapes fabricated by spray pyrolysis. The novel GPM method was also applied for Bi-2212/Ag PIT composite wire, and found to be very effective for improving the distribution of voids, which caused from the melt-solidifying process. The GPM showed a marked effect for obtaining homogeneous long wire. A 1 T class coil was successfully fabricated with monocore wire.

  20. The Lyman alpha bulge of Jupiter - Effects of non-thermal velocity field

    NASA Technical Reports Server (NTRS)

    Ben Jaffel, Lotfi; Clarke, John T.; Prange, Renee; Gladstone, G. R.; Vidal-Madjar, Alfred

    1993-01-01

    We outline for the first time the effect of such nonthermal line broadening processes as turbulence, random waves, convection, etc., on the shape and intensity of the H Ly-alpha line resonance scattered from the atmosphere of Jupiter. We show how a nonthermal velocity field confined to the bulge region, in the upper atmosphere of Jupiter, may account for most of the H Ly-alpha bulge features. Both the shape and the brightness of the Ly-alpha line from the bulge region as reported by the IUE instrument and the Voyager UV Spectrometer can be recovered assuming resonant scattering with a total atomic hydrogen of about 4 x 10 exp 17/sq cm, and a nonthermal component H of about 2 x 10 exp 15/sq cm above the thermopause.

  1. The Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest: The X-ray Catalog

    NASA Technical Reports Server (NTRS)

    Yang, Y.; Mushotzky, R. F.; Steffen, A. T.; Barger, A. J.; Cowie, L. L.

    2004-01-01

    We present the X-ray catalog and basic results from our Chandra Large Area Synoptic X-ray Survey (CLASXS) of the Lockman Hole-Northwest field. Our 9 ACIS-I fields cover a contiguous solid angle of approx. 0.4 sq deg and reach fluxes of 5 x 10(exp -16) ergs/sq cm/s (0.4-2 keV) and 3 x 10(exp -15) ergs/sq cm/s (2-8 keV). Our survey bridges the gap between ultradeep pencil-beam surveys, such as the Chandra Deep Fields (CDFs), and shallower, large area surveys, allowing a better probe of the X-ray sources that contribute most of the 2-10 keV cosmic X-ray background (CXB). We find a total of 525 X-ray point sources and 4 extended sources. At approx. 10(exp -14)ergs/sq cm/s (2-8 keV), our number counts are significantly higher than those of several non-contiguous, large area surveys. Such a large difference is an indication of clustering in the X-ray sources. On the other hand, the integrated flux from the CLASXS field, combined with ASCA and Chandra ultradeep surveys, is consistent with results from other large area surveys, within the variance of the CXB. We see spectral evolution in the hardening of the sources at fluxes below 10(exp -14) ergs/sq cm/s, which agrees with previous observations from Chandra and XMM-Newton. About 1/3 of the sources in the CLASXS field have multiple observations, allowing variability tests. Above 4 x 10(exp -14) ergs/sq cm/s (0.4-8 keV), approx. 61% of the sources are variable. We also investigated the spectral variability of the variable sources. While most show spectral softening with increasing flux, or no significant spectral change, there are a few sources that show a different trend. Four extended sources in CLASXS is consistent with the previously measured LogN-LogS of galaxy clusters. Using X-ray spectra and optical colors, we argue that 3 of the 4 extended sources are galaxy clusters or galaxy groups. We report the discovery of a gravitational lensing arc associated with one of these sources. Using red sequence and brightest

  2. Preliminary Results of Field Emission Cathode Tests

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Kovaleski, Scott D.

    2001-01-01

    Preliminary screening tests of field emission cathodes such as chemical vapor deposited (CVD) diamond, textured pyrolytic graphite, and textured copper were conducted at background pressures typical of electric thruster test facilities to assess cathode performance and stability. Very low power electric thrusters which provide tens to hundreds micronewtons of thrust may need field emission neutralizers that have a capability of tens to hundreds of microamperes. From current voltage characteristics, it was found that the CVD diamond and textured metals cathodes clearly satisfied the Fowler-Nordheim emission relation. The CVD diamond and a textured copper cathode had average current densities of 270 and 380 mA/sq cm, respectively, at the beginning-of-life. After a few hours of operation the cathode emission currents degraded by 40 to 75% at background pressures in the 10(exp -5) Pa to 10(exp -4) Pa range. The textured pyrolytic graphite had a modest current density at beginning-of-life of 84 mA/sq cm, but this cathode was the most stable of all. Extended testing of the most promising cathodes is warranted to determine if current degradation is a burn-in effect or whether it is a long-term degradation process. Preliminary experiments with ferroelectric emission cathodes, which are ceramics with spontaneous electric polarization, were conducted. Peak current densities of 30 to 120 mA/sq cm were obtained for pulse durations of about 500 ns in the 10(exp -4) Pa pressure range.

  3. Microstructural Evolution of Ti-6Al-4V during High Strain Rate Conditions of Metal Cutting

    NASA Technical Reports Server (NTRS)

    Dong, Lei; Schneider, Judy

    2009-01-01

    The microstructural evolution following metal cutting was investigated within the metal chips of Ti-6Al-4V. Metal cutting was used to impose a high strain rate on the order of approx.10(exp 5)/s within the primary shear zone as the metal was removed from the workpiece. The initial microstructure of the parent material (PM) was composed of a bi-modal microstructure with coarse prior grains and equiaxed primary located at the boundaries. After metal cutting, the microstructure of the metal chips showed coarsening of the equiaxed primary grains and lamellar. These metallographic findings suggest that the metal chips experienced high temperatures which remained below the transus temperature.

  4. Column measurements of stratospheric trace species over Are, Sweden in the winter of 1991-1992

    NASA Technical Reports Server (NTRS)

    Bell, W.; Martin, N. A.; Gardiner, T. D.; Swann, N. R.; Woods, P. T.; Fogal, P. F.; Waters, J. W.

    1994-01-01

    Total vertical column amounts of stratospheric HCl, HF, ClONO2 and HNO3 are reported from high resolution infrared solar absorption spectra taken during the European Arctic Stratospheric Ozone Experiment (EASOE) in the winter of 1991-1992. These ground based measurements were made near Are in North Sweden (63.4 deg N, 13.1 deg E) at an altitude of 800 m using a Fourier transform spectrometer and tunable diode laser heterodyne spectrometer. On 9th January 1992 the HCl vertical column dropped to 1.2 x 10(exp 15) molecules/sq cm from a November average of 3.6 x 10(exp 15) molecules/sq cm. The HCl drop occurred at a time when Are was below the polar vortex and the lower stratospheric ClO column above Are was elevated to approximately 2 x 10(exp 15) molecules/sq cm as measured by the Microwave Limb Sounder experiment on the Upper Atmosphere Research Satellite. These measurements indicate conversion of lower stratospheric chlorine from reservoir to chemically active forms.

  5. Detection of high-energy gamma radiation from quasar 3C 279 by the EGRET telescope on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Bertsch, D. L.; Fichtel, C. E.; Hunter, S. D.; Kwok, P. W.; Thompson, D. J.; Mattox, J. R.; Kanbach, G.; Nel, H. I.; Sreekumar, P.

    1992-01-01

    Intense gamma radiation has been observed from the direction of the quasar 3C 279 throughout the energy range from 30 MeV to over 5 GeV by the Energetic Gamma Ray Experiment Telescope (EGRET) during the period June 15-28, 1991. Its spectrum is well represented by a photon differential power-law exponent of 2.0 +/- 0.1, with a photon intensity above 100 MeV of (2.8 +/- 0.4) x 10 exp -6/sq cm s. For E is greater than 100 MeV, the 2-sigma upper limits were 1.0 x 10 exp -6/sq cm s in 1973 from the SAS 2 observations and 0.3 x 10 exp -6/sq cm s for the combined 1976, 1978, and 1980 COS B observations. Hence, there has been a large increase in high-energy gamma-ray intensity relative to the earlier times, as there has been in the radio, infrared, optical, and X-ray ranges. This source is the most distant and by far the most luminous gamma-ray source yet detected.

  6. Toward 10(exp 10) Contrast for Terrestrial Exoplanet Detection: Demonstration of Wavefront Correction in a Shaped Pupil Coronagraph

    NASA Technical Reports Server (NTRS)

    Belikov, Ruslan; Give'on, Amir; Trauger, John T.; Carr, Michael; Kasdin, Jeremy N.; Vanderbei, Robert J.; Shi, Fang; Balasubramanian, Kunjithapatham; Kuhnert, Andreas

    2006-01-01

    Experimental demonstration of wavefront control with shaped pupils. Contrast level is maintained across different wavelengths and 10% broadband light. Further improvements in contrast believed to have been possible with more time and parameter optimizations.

  7. The morphology of 20 x 10 exp 6 K plasma in large non-impulsive solar flares

    NASA Technical Reports Server (NTRS)

    Acton, Loren W.; Feldman, Uri; Bruner, Marilyn E.; Doschek, George A.; Hirayama, Tadashi; Hudson, Hugh S.; Lemen, James R.; Ogawara, Yoshiaki; Strong, Keith T.; Tsuneta, Saku

    1992-01-01

    We have examined images of 10 flares observed by the Soft X-ray Telescope on-board the Yohkoh spacecraft. These images show that the hottest portion of the soft X-ray flare is located in compact regions that appear to be situated at the tops of loops. These compact regions form at, or shortly after, flare onset, and persist well into the decay phase of the flares. In some cases, the compact regions are only a few thousand kilometers in size and are small compared to the lengths of flaring loops. This is inconsistent with the smoother intensity distribution along the loops expected from models of chromospheric evaporation.

  8. Low Luminosity States of the Black Hole Candidate GX 339-4. 2; Timing Analysis

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Wilms, Joern; Dove, James B.

    1999-01-01

    Here we present timing analysis of a set of eight Rossi X-ray Timing Explorer (RXTE) observations of the black hole candidate GX 339-4 that were taken during its hard/low state. On long time scales, the RXTE All Sky Monitor data reveal evidence of a 240 day periodicity, comparable to timescales expected from warped, precessing accretion disks. On short timescales all observations save one show evidence of a persistent f(qpo approximately equals 0.3 Hz quasi-periodic oscillations (QPO)). The broad band (10 (exp -3) to 10 (exp2) Hz) power appears to be dominated by two independent processes that can be modeled as very broad Lorentzians with Q approximately less than - 1. The coherence function between soft and hard photon variability shows that if these are truly independent processes, then they are individually coherent, but they are incoherent with one another. This is evidenced by the fact that the coherence function between the hard and soft variability is near unity between 5 x 10 (exp -3) but shows evidence of a dip at f approximately equals 1 Hz. This is the region of overlap between the broad Lorentzian fits to the Power Spectral Density (PSD). Similar to Cyg X-1, the coherence also drops dramatically at frequencies approximately greater than 1O Hz. Also similar to Cyg X-1, the hard photon variability is seen to lag the soft photon variability with the lag time increasing with decreasing Fourier frequency. The magnitude of this time lag appears to be positively correlated with the flux of GX 339-4. We discuss all of these observations in light of current theoretical models of both black hole spectra and temporal variability.

  9. A Suzaku X-ray Observation of One Orbit of the Supergiant Fast X-ray Transient IGR J16479-4514

    NASA Technical Reports Server (NTRS)

    Sidoli, L.; Esposito, P.; Sguera, V.; Bodaghee, A.; Tomsick, J. A.; Pottschmidt, K.; Rodriguez, J.; Ramano, P.; Wilms, J.

    2013-01-01

    We report on a 250 ks long X-ray observation of the supergiant fast X-ray transient (SFXT) IGR J16479-4514 performed with Suzaku in 2012 February. During this observation, about 80% of the short orbital period (P(sub orb) approximates 3.32 days) was covered as continuously as possible for the first time. The source light curve displays variability of more than two orders of magnitude, starting with a very low emission state (10(exp -13) erg / sq cm/s; 1-10 keV) lasting the first 46 ks, consistent with being due to the X-ray eclipse by the supergiant companion. The transition to the uneclipsed X-ray emission is energy dependent. Outside the eclipse, the source spends most of the time at a level of 6-7X10)(exp-12) erg/sq. cm/s) punctuated by two structured faint flares with a duration of about 10 and 15 ks, respectively, reaching a peak flux of 3-4X10(exp -11) erg/sq. cm./S, separated by about 0.2 in orbital phase. Remarkably, the first faint flare occurs at a similar orbital phase of the bright flares previously observed in the system. This indicates the presence of a phase-locked large scale structure in the supergiant wind, driving a higher accretion rate onto the compact object. The average X-ray spectrum is hard and highly absorbed, with a column density, NH, of 10*exp 23)/sq cm, clearly in excess of the interstellar absorption. There is no evidence for variability of the absorbing column density, except that during the eclipse, where a less absorbed X-ray spectrum is observed. A narrow Fe K-alpha emission line at 6.4 keV is viewed along the whole orbit, with an intensity which correlates with the continuum emission above 7 keV. The scattered component visible during the X-ray eclipse allowed us to directly probe the wind density at the orbital separation, resulting in rho(sub w)=7X10(exp -14) g/cubic cm. Assuming a spherical geometry for the supergiant wind, the derived wind density translates into a ratio M(sub w)/v(sub infinity) = 7X10(exp -17) Solar M

  10. High Mobility SiGe/Si n-Type Structures and Field Effect Transistors on Sapphire Substrates

    NASA Technical Reports Server (NTRS)

    Alterovitz, Samuel A.; Ponchak, George E.; Mueller, Carl H.; Croke, Edward T.

    2004-01-01

    SiGe/Si n-type modulation doped field effect transistors (MODFETs) fabricated on sapphire substrates have been characterized at microwave frequencies for the first time. The highest measured room temperature electron mobility is 1380 sq cm/V-sec at a carrier density of 1.8 x 10(exp 12)/sq cm for a MODFET structure, and 900 sq cm/V-sec at a carrier density of 1.3 x 10/sq cm for a phosphorus ion implanted sample. A two finger, 2 x 200 micron gate n-MODFET has a peak transconductance of 37 mS/mm at a drain to source voltage of 2.5 V and a transducer gain of 6.4 dB at 1 GHz.

  11. Development of a Spectral Model Based on Charge Transport for the Swift/BAT 32K CdZnTe Detector Array

    NASA Technical Reports Server (NTRS)

    Sato, Goro; Parsons, Ann; Hillinger, Derek; Suzuki, Masaya; Takahashi, Tadayuki; Tashiro, Makoto; Nakazawa, Kazuhiro; Okada, Yuu; Takahashi, Hiromitsu; Watanabe, Shin

    2005-01-01

    The properties of 32K CdZnTe (4 x 4 sq mm large, 2 mm thick) detectors have been studied in the pre-flight calibration of the Burst Alert Telescope (BAT) on-board the Swift Gamma-ray Burst Explorer (scheduled for launch in November 2004). In order to understand the energy response of the BAT CdZnTe array, we first quantify the mobility-lifetime (mu tau) products of carriers in individual CdZnTe detectors, which produce a position dependency in the charge induction efficiency and results in a low energy tail in the energy spectrum. Based on a new method utilizing (57)Co spectra obtained at different bias voltages, the mu tau for electrons ranges from 5.0 x 10(exp -4) to 1.0 x 10(exp -2) sq cm/V while the mu tau for holes ranges from 1.3 x 10(exp -5 to 1.8 x 10(exp -4) sq cm/V. We find that this wide distribution of mu tau products explains the large diversity in spectral shapes between CdZnTe detectors well. We also find that the variation of mu tau products can be attributed to the difference of crystal ingots or manufacturing harness. We utilize the 32K sets of extracted mu tau products to develop a spectral model of the detector. In combination with Monte Carlo simulations, we can construct a spectral model for any photon energy or any incident angle.

  12. Infrared Measurements of Atmospheric Gases Above Mauna Loa, Hawaii, in February 1987

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Goldman, A.; Murcray, F. J.; Murcray, F. H.; Blatherwick, R. D.; Murcray, D. G.

    1988-01-01

    Infrared solar absorption spectra recorded at 0.02/ cm resolution from the National Oceanic and Atmospheric Administration (NOAA) Geophysical Monitoring for Climate Change (GMCC) program station at Mauna Loa, Hawaii (latitude 19.5 deg N, longitude 155.6 deg W, elevation 3.40 km), in February 1997 have been analyzed to determine simultaneous total vertical column amounts for 13 atmospheric gases. Average tropospheric concentrations of CO2, N2O, CH4, and CHCIF2 and the daytime diurnal variations or the total columns of NO and NO2 have also been inferred. The retrieved total columns (in molecules /sq cm) of the nondiurnally varying gases are 1.6 +/- 0.2 x 10(exp 15) for HCl, 5.9 +/- 1.2 x 10(exp 15) for HNO3, 2.0 +/- 0.2 x 10(exp 21) for H2O16, 4.4 +/- 0.7 x 10(exp 18) for H2O18, 2.7 +/- 0.1 x 10(exp 17) for HDO, 2.3 +/- 0.2 x 10(exp 19) for CH4, 5.0 +/- 0.5 x 10(exp 21) for CO2, 6.7 +/- 0.8 x 10(exp 18) for O3, 4.3 +/- 0.4 x 10(exp 18) for N2O, 1.0 +/- 0.2 x 10(exp 16) for C2H6, and 9.7 +/- 2.5 x 10(exp 14) for CHClF2. We compare the total column measurements of HCl and HNO3 with previously reported ground-based, aircraft, and satellite measurements. The results for HCl are or particular interest because of the expected temporal increase in the concentration of this gas in the stratosphere. However, systematic differences among stratospheric HCl total column measurements from 1978 to 1980 and the absence of observations of free tropospheric HCl above Mauna Loa make it impossible to obtain a reliable estimate of the trend in the total burden of HCl. The measured HNO3 total column is consistent with aircraft measurements from approx. 12 km altitude. The O3 total column deduced from the IR spectra agrees with correlative Mauna Loa Umkehr measurements within the estimated error limits. The column-averaged D/H ratio of water vapor is (68 +/- 9) x- 10(exp -6), which is 0.44 +/- 0.06 times the reference value of 155.76 x 10(exp -6) for standard mean ocean water (SMOW). This

  13. FUSE Observations of Warm Gas in the Cooling Flow Clusters A1795 and A2597

    NASA Technical Reports Server (NTRS)

    Oegerle, W. R.; Cowie, L.; Davidsen, A.; Hu, E.; Hutchings, J.; Murphy, E.; Sembach, K.; Woodgate, B.; Fisher, Richard R. (Technical Monitor)

    2001-01-01

    We present far-ultraviolet spectroscopy of the cores of the massive cooling flow clusters Abell 1795 and 2597 obtained with FUSE. As the intracluster gas cools through 3 x 10(exp 5)K, it should emit strongly in the O VI lambda(lambda)1032,1038 resonance lines. We report the detection of O VI (lambda)1032 emission in A2597, with a line flux of 1.35 +/- 0.35 x 10(exp -15) erg/sq cm s, as well as detection of emission from C III (lambda)977. A marginal detection of C III (lambda)977 emission is also reported for A1795. These observations provide evidence for a direct link between the hot (10(exp 7) K) cooling flow gas and the cool (10(exp 4) K) gas in the optical emission line filaments. Assuming simple cooling flow models, the O VI line flux in A2597 corresponds to a mass deposition rate of approx. 40 solar mass /yr within the central 36 kpc. Emission from O VI (lambda)1032 was not detected in A1795, with an upper limit of 1.5 x 10(exp -15) erg/sq cm s, corresponding to a limit on the mass cooling flow rate of M(28 kpc) less than 28M solar mass/ yr. We have considered several explanations for the lack of detection of O VI emission in A1795 and the weaker than expected flux in A2597, including extinction by dust in the outer cluster, and quenching of thermal conduction by magnetic fields. We conclude that a turbulent mixing model, with some dust extinction, could explain our O VI results while also accounting for the puzzling lack of emission by Fe(sub XVII) in cluster cooling flows.

  14. Kinetics of the Cl(2)P(J)) + CH4 Reaction: Effects of Secondary Chemistry Below 300 K

    NASA Technical Reports Server (NTRS)

    Wang, J. J.; Keyser, Leon F.

    2000-01-01

    Absolute rate data for the Cl(2)P(J) + CH4 yields HCl + CH3 reaction have been obtained from 218 to 298 K by using the discharge-flow resonance fluorescence technique at I Torr total pressure. The result at 298 K is (10.1 +/- 0.6) x 10(exp -14) cu cm/molecule/s. The temperature dependence in Arrhenius form is (6.5 +/- 0.9 ) x 10(exp -12) exp[(-1235 +/- 34 )/T]. The errors given are one standard deviation; overall experimental error is estimated at +/- 15%. Because of the relatively large disagreement among earlier measurements at low temperatures, the results were examined for possible effects of non-Boltzmann spin distribution and vibrational excitation of CH4, secondary chemistry of CH3 radicals, and impurities in the CH4 source. There was no significant change in the observed rate constant when an efficient spin quencher, CF4, was added and estimates indicate that vibrational partitioning in CH4 should be at the ambient reactor temperature before the start of the reaction. The results were also independent of the source of Cl atoms (microwave discharge or thermal decomposition of Cl2) and whether CH4 was purified in-situ. However, the observed rate constant did depend on initial Cl atom concentrations and to a lesser extent on CH4 concentrations. Numerical simulations were used to assess the importance of secondary chemistry over a range of reactant concentrations

  15. The nature of the compact X-ray source in the supernova remnant G27.4+0.0

    NASA Technical Reports Server (NTRS)

    Helfand, David J.; Becker, R. H.; Hawkins, G.; White, R. L.

    1994-01-01

    High-resolution X-ray imaging data obtained with ROSAT is used to constrain the nature of the central compact source in the supernova remnant G27.4+0.0. Diffuse emission is seen from throughout the approximately 4 min diameter radio shell, while the central source remains unresolved at approximately 3 sec. We combine archival data from the Einstein HRI, IPC, and MPC with the ROSAT HRI data to define the X-ray spectra of the diffuse and point-like emission. The bulk of the shell radiation is consistent with that of a approximately 10(exp 7) K plasma, although a higher temperature component is also suggested by the data; coupled with the remnant's size and distance, we derive an age of between 500 and 2500 yr. The point source has a substantially harder spectrum, with a power-law photon index less than or approximately equal to 1. A search for periodic modulation from the point source yields upper limits ranging from 10%-35% for periods between 0.025 and 1000 s, depending on the assumed pulse shape. No aperiodic variability on timescales of from 10(exp 3) to 10(exp 8) s is required, although a factor of approximately 2 change between the Einstein and ROSAT eras is possible. We show that the point source cannot represent thermal emission from the surface of a young neutron star and is unlikely to be explained as nonthermal, Crab-like X-ray pulses or a small synchrotron nebula. The most likely models involve accretion-powered systems -- either a wind-fed neutron star with a massive companion or a low-mass X-ray binary. In all probability, this is the youngest X-ray binary in the Galaxy.

  16. Soft x-ray properties of the binary millisecond pulsar J0437-4715

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Martin, Christopher; Marshall, Herman L.

    1995-01-01

    We obtained a light curve for the 5.75 ms pulsar J0437-4715 in the 65-120 A range with 0.5 ms time resolution using the Deep Survey instrument on the EUVE satellite. The single-peaked profile has a pulsed fraction of 0. 27 +/- 0.05, similar to the ROSAT data in the overlapping energy band. A combined analysis of the EUVE and ROSAT data is consistent with a power-law spectrum of energy index alpha = 1.2-1.5, intervening column density NH = (5-8) x 10(exp 19)/sq cm, and luminosity 5.0 x 10(exp 30) ergs/s in the 0.1-2. 4 keV band. We also use a bright EUVE/ROSAT source only 4.3 deg from the pulsar, the Seyfert galaxy RX J0437.4-4711 (= EUVE J0437-471 = lES 0435-472), to obtain an independent upper limit on the intervening absorption to the pulsar, NH less than 1.2 x 10(exp 20)/sq cm. Although a blackbody spectrum fails to fit the ROSAT data, two-component spectral fits to the combined EUVE/ROSAT data are used to limit the temperatures and surface areas of thermal emission that might make partial contributions to the flux. A hot polar cap of radius 50-600 m and temperature (1.0-3.3) x 10(exp 6) K could be present. Alternatively, a larger region with T = (4-12) x 10(exp 5) K and area less than 200 sq km, might contribute most of the EUVE and soft X-ray flux, but only if a hotter component were present as well. Any of these temperatures would require some mechanism(s) of surface reheating to be operating in this old pulsar, the most plausible being the impact of accelerated electrons and positrons onto the polar caps. The kinematically corrected spin-down power of PSR J0437-4715 is only 4 x 10(exp 33) ergs/s, which is an order of magnitude less than that of the lowest-luminosity gamma-ray pulsars Geminga and PSR B1055-52. The absence of high-energy gamma-rays from PSR J0437-4715 might signify an inefficient or dead outer gap accelerator, which in turn accounts for the lack of a more luminous reheated surface such as those intermediate-age gamma-ray pulsars may have.

  17. Soft X-Ray Properties of the Binary Millisecond Pulsar J0437-4715

    NASA Technical Reports Server (NTRS)

    Halpern, Jules P.; Martin, Christopher; Marshall, Herman, L.; Oliversen, Ronald (Technical Monitor)

    2001-01-01

    We obtained a light curve for the 5.75 ms pulsar J0437-4715 in the 65-120 A range with 0.5 ms time resolution using the Deep Survey instrument on the EUVE satellite. The single-peaked profile has a pulsed fraction of 0.27 +/- 0.05, similar to the ROSAT data in the overlapping energy band. A combined analysis of the EUVE and ROSAT data is consistent with a power-law spectrum of energy index alpha = 1.2 - 1.5, intervening column density N(sub H) = (5 - 8) x 10(exp 19)/sq cm, and luminosity 5.0 x 10(exp 30) ergs/s in the 0.1 - 2.4 keV band. We also use a bright EUVE/ROSAT source only 4.2 min. from the pulsar, the Seyfert galaxy RX J0437.4-4711 (= EUVE J0437-471 = IES 0435-472), to obtain an independent upper limit on the intervening absorption to the pulsar, N(sub H) less than 1.2 x 10(exp 20)/sq cm. Although a blackbody spectrum fails to fit the ROSAT data, two-component spectral fits to the combined EUVE/ROSAT data are used to limit the temperatures and surface areas of thermal emission that might make partial contributions to the flux. A hot polar cap of radius 50 - 600 m and temperature (1.0 - 3.3) x 10(exp 6) K could be present. Alternatively, a larger region with T = (4 - 12) x 10(exp 5) K and area less than 200 sq km, might contribute most of the EUVE and soft X-ray flux, but only if a hotter component were present as well. Any of these temperatures would require some mechanism(s) of surface reheating to be operating in this old pulsar, the most plausible being the impact of accelerated electrons and positrons onto the polar caps. The kinematically corrected spin-down power of PSR J0437-4715 is only 4 x 10(exp 33) ergs/s, which is an order of magnitude less than that of the lowest-luminosity gamma-ray pulsars Geminga and PSR B1055-52. The absence of high-energy gamma-rays from PSR J0437-4715 might signify an inefficient or dead outer gap accelerator, which in turn accounts for the lack of a more luminous reheated surface such as those intermediate-age gamma

  18. The Einstein All-Sky Slew Survey

    NASA Technical Reports Server (NTRS)

    Elvis, Martin S.

    1992-01-01

    The First Einstein IPC Slew Survey produced a list of 819 x-ray sources, with f(sub x) approximately 10(exp -12) - 10(exp -10) erg/sq cm s and positional accuracy of approximately 1.2 feet (90 percent radius). The aim of this program was to identify these x-ray sources.

  19. Modeling of the initiation and evolution of a laser-ionized column in the lower atmosphere - 314.5 nm wavelength resonant multiphoton ionization of naturally occurring argon

    NASA Technical Reports Server (NTRS)

    Fetzer, G. J.; Stockley, J. E.

    1992-01-01

    A 3+1 resonant multiphoton ionization process in naturally occurring argon is studied at 314.5 nm as a candidate for providing a long ionized channel through the atmosphere. Results are presented which indicate peak electron densities up to 10 exp 8/cu cm can be created using laser intensities on the order of 10 exp 8 W/sq cm.

  20. Test Status for Proposed Coupling of a Gravitational Force to Extreme Type II YBCO Ceramic Superconductors

    NASA Technical Reports Server (NTRS)

    Noever, David; Li, Ning; Robertson, Tony; Koczor, Ron; Brantley, Whitt

    1999-01-01

    As a Bose condensate, superconductors provide novel conditions for revisiting previously proposed couplings between electromagnetism and gravity. Strong variations in Cooper pair electron density, large conductivity and low magnetic permeability define superconductive and degenerate condensates without the traditional density limits imposed by the Fermi energy (about 10-6 g/cu cm). Recent experiments have reported anomalous weight loss for a test mass suspended above a rotating Type II, YBCO superconductor, with the percentage change (0.05-2.1%) independent of the test mass' chemical composition and diamagnetic properties. A variation of 5 parts per 10(exp 4) was reported above a stationary (non-rotating) superconductor. In the present experiments reported using a sensitive gravimeter (resolution <10(exp -9) unit gravity or variation of 10(exp -6) cm/sq s in accelerations), bulk YBCO superconductors were stably levitated in a DC magnetic field (0.6 Tesla) subject to lateral AC fields (60 Gauss at 60 Hz) and rotation. With magnetic shielding, thermal control and buoyancy compensation, changes in acceleration were measured to be less than 2 parts in 10(exp 8) of the normal gravitational acceleration. This result puts new limits on the strength and range of the proposed coupling between high-Tc superconductors and gravity. Latest test results will be reported, along with status for future improvements and prospects.

  1. Fourier transform infrared studies of the interaction of HCl with model polar stratospheric cloud films

    NASA Technical Reports Server (NTRS)

    Koehler, Birgit G.; Mcneill, Laurie S.; Middlebrook, Ann M.; Tolbert, Margaret A.

    1993-01-01

    Heterogeneous reactions involving hydrochloric acid adsorbed on the surfaces of polar stratospheric clouds (PSCs) are postulated to contribute to polar ozone loss. Using FTIR spectroscopy to probe the condensed phase, we have examined the interaction of HCl with ice and nitric acid trihydrate (NAT) films representative of types II and I PSCs, respectively. For HCl pressures in the range of 10 exp -7 to 10 exp -5 Torr, our FTIR studies show that a small amount of crystalline HCl-6H2O formed on or in ice at 155 K. However, for higher HCl pressures, we observed that the entire film of ice rapidly converted into an amorphous 4:1 H2O:HCl mixture. From HCl-uptake experiments with P(HCl) = 8 x 10 exp -7 Torr, we estimate roughly that the diffusion coefficient of HCl in ice is around 2 x 10 exp -12 sq cm/s at 158 K. For higher temperatures more closely approximating those found in the stratosphere, we were unable to detect bulk HCl uptake by ice. Indirect evidence suggests that HCl adsorption onto the surface of model PSC films inhibited the evaporation of both ice and NAT by 3-5 K.

  2. OSSE observations of 1E 1740.7-2942 in 1992 September

    NASA Technical Reports Server (NTRS)

    Jung, G. V.; Kurfess, D. J.; Johnson, W. N.; Kinzer, R. L.; Grove, J. E.; Strickman, M. S.; Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.

    1995-01-01

    We present data on the galactic X-ray source 1E 1740.7-2942 from the Oriented Scintillation Spectrometer Experiment (OSSE) on board NASA's Compton Gamma Ray Observatory (CGRO). Episodes of increased low-energy gamma radiation have been reported from this source, including 1-day events in 1990 October and 1992 September. These events, of intensity 7 x 10(exp -3) and 4 x 10(exp -3) photons/sq cm/s, respectively, have been interpreted as broadened and redshifted positron annihilation radiation. OSSE conducted observations of the Galactic Center region during a 21-day interval from 1992 September 17 thru 1992 October 8. This includes the time of increased 200-450 keV emission from 1E 1740.7-2942 reported by SIGMA. The OSSE observations do not confirm this event. For the specific outburst recorded by SIGMA, 1992 Sep. 19.42-20.58 (UT), OSSE data provide an upper limit (3 sigma) of 2.4 x 10(exp -3) photons/sq cm/s.

  3. Rate Coefficients of C2H with C2H4, C2H6, and H2 from 150 to 359 K

    NASA Technical Reports Server (NTRS)

    Opansky, Brian J.; Leone, Stephen R.

    1996-01-01

    Rate coefficients for the reactions C2H with C2H4, C2H6, and H2 are measured over the temperature range 150-359 K using transient infrared laser absorption spectroscopy. The ethynyl radical is formed by photolysis of C2H2 with a pulsed excimer laser at 193 nm, and its transient absorption is monitored with a color center laser on the Q(sub 11)(9) line of the A(sup 2) Pi-Chi(sup 2) Sigma transition at 3593.68 cm(exp -1). Over the experimental temperature range 150-359 K the rate constants of C2H with C2H4, C2H6, and H2 can be fitted to the Arrhenius expressions k(sub C2H4) = (7.8 +/- 0.6) x 10(exp -11) exp[(134 +/- 44)/T], k(sub C2H6) = (3.5 +/- 0.3) x 10(exp -11) exp[(2.9 +/- 16)/T], and k(sub H2) = (1.2 +/- 0.3) x 10(exp -11) exp[(-998 +/- 57)]/T cm(exp 3) molecule(exp -1) sec(exp -1). The data for C2H with C2H4 and C2H6 indicate a negligible activation energy to product formation shown by the mild negative temperature dependence of both reactions. When the H2 data are plotted together with the most recent high-temperature results from 295 to 854 K, a slight curvature is observed. The H2 data can be fit to the non-Arrhenius form k(sub H2) = 9.2 x 10(exp -18) T(sup 2.17 +/- 0.50) exp[(-478 +/- 165)/T] cm(exp 3) molecules(exp -1) sec(exp -1). The curvature in the Arrhenius plot is discussed in terms of both quantum mechanical tunneling of the H atom from H2 to the C2H radical and bending mode contributions to the partition function.

  4. Performance of transonic fan stage with weight flow per unit annulus area of 178 kilograms per second per square meter (6.5(lb/sec)/(sq ft))

    NASA Technical Reports Server (NTRS)

    Moore, R. D.; Urasek, D. C.; Kovich, G.

    1973-01-01

    The overall and blade-element performances are presented over the stable flow operating range from 50 to 100 percent of design speed. Stage peak efficiency of 0.834 was obtained at a weight flow of 26.4 kg/sec (58.3 lb/sec) and a pressure ratio of 1.581. The stall margin for the stage was 7.5 percent based on weight flow and pressure ratio at stall and peak efficiency conditions. The rotor minimum losses were approximately equal to design except in the blade vibration damper region. Stator minimum losses were less than design except in the tip and damper regions.

  5. Electrospun Polyaniline/Polyethylene Oxide Nanofiber Field Effect Transistor

    NASA Technical Reports Server (NTRS)

    Pinto, N. J.; Johnson, A. T.; MacDiarmid, A. G.; Mueller, C. H.; Theofylaktos, N.; Robinson, D. C.; Miranda, F. A.

    2003-01-01

    We report on the observation of field effect transistor (FET) behavior in electrospun camphorsulfonic acid doped polyaniline(PANi)/polyethylene oxide(PE0) nanofibers. Saturation channel currents are observed at surprisingly low source/drain voltages. The hole mobility in the depletion regime is 1.4 x 10(exp -4) sq cm/V s while the 1-D charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating 1-D polymer FET's.

  6. On the Extended Emission of the Anomalous X-ray Pulsar IE 1547.0-5408

    NASA Technical Reports Server (NTRS)

    Olausen, S. A.; Kaspi, V. M.; Ng, C. -Y.; Zhu, W. W.; Gavriil, F. P.; Woods, P. M.

    2012-01-01

    We present an analysis of the extended emission around the anomalous X-ray pulsar IE 1547.0-5408 using four XMM-Newton observations taken with the source in varying states of outburst as well as in quiescence. We find that the extended emission flux is highly variable and strongly correlated with the flux of the magnetar. Based on this result, as well as on spectral and energetic considerations, we conclude that the extended emission is dominated by a dust-scattering halo and not a pulsar wind nebula (P-VVN), as has been previously argued. We obtain an upper limit on the 2-10 keV flux of a possible PWN of 4.7 x 10(exp -14) erg/s/sq cm, three times less than the previously claimed value, implying an efficiency for conversion of spin-down energy into nebular luminosity of <9 x 10(exp -4) .

  7. Description of a subset of single events from the BATSE gamma ray burst data

    NASA Technical Reports Server (NTRS)

    Kouveliotou, Chryssa; Paciesas, William S.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.

    1992-01-01

    About 15 percent of the gamma ray bursts in the Burst and Transient Source Experiment (BATSE) data exhibit a simple light curve consisting mainly of a single pulse without fine substructures. In 12 of the burst profiles, the pulse shapes show a linear rise and decay. Three events have a distinct sharp rise followed by a long, almost exponential decay. Searches based on only a sharp rise selection criterion resulted in five more grbs with different profile complexities. In one case, we identify an envelope of fast oscillations with a long, softer tail lasting about 100 seconds. The majority of events were detectable at energies above 300 keV, with tentative estimates for fluences that vary between 4.0 x 10(exp -8) and 5.4 x 10(exp -6) ergs/sq cm. We describe here their general characteristics (durations, rise-decay times) and their hardness ratios.

  8. Time-Dependent Photodissociation Regions

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; Natta, Antonella

    1995-01-01

    We present theoretical models of the time-dependent thermal and chemical structure of molecular gas suddenly exposed to far-ultraviolet (FUV) (6 eV less than hv less than 13.6 eV) radiation fields and the consequent time- dependent infrared emission of the gas. We focus on the response of molecular hydrogen for cloud densities ranging from n = 10(exp 3) to 10(exp 6)/cu cm and FUV fluxes G(sub 0) = 10(exp 3)-10(exp 6) times the local FUV interstellar flux. For G(sub 0)/n greater than 10(exp -2) cu cm, the emergent H(sub 2) vibrational line intensities are initially larger than the final equilibrium values. The H(sub 2) lines are excited by FUV fluorescence and by collisional excitation in warm gas. Most of the H(sub 2) intensity is generated at a characteristic hydrogen column density of N approximately 10(exp 21)/sq cm, which corresponds to an FUV optical depth of unity caused by dust opacity. The time dependence of the H(sub 2) intensities arises because the initial abundances of H(sub 2) at these depths is much higher than the equilibrium values, so that H(sub 2) initially competes more effectively with dust in absorbing FUV photons. Considerable column densities of warm (T approximately 1000) K H(sub 2) gas can be produced by the FUV pumping of H(sub 2) vibrational levels followed by collisional de-excitation, which transfers the energy to heat. In dense (n greater than or approximately 10(exp 5)/cu cm) gas exposed to high (G(sub 0) greater than or approximately 10(exp 4)) fluxes, this warm gas produces a 2-1 S(1)/1-0 S(l) H(sub 2) line ratio of approximately 0.1, which mimics the ratio found in shocked gas. In lower density regions, the FUV pumping produces a pure-fluorescent ratio of approximately 0.5. We also present calculations of the time dependence of the atomic hydrogen column densities and of the intensities of 0 I 6300 A, S II 6730 A, Fe II 1.64 microns, and rotational OH and H20 emission. Potential applications include star-forming regions, clouds

  9. Heterogeneous Uptake and Conversion of HOBr on H2SO4 at Upper Tropospheric and Stratospheric Temperatures (255 - 210 K)

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Ashbourn, Samantha F. M.; Rammer, Thomas A.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Halogen species are known to catalytically destroy ozone in several different regions of the atmosphere. In addition to directly destroying ozone, bromine compounds can indirectly enhance ozone loss through coupling to other radical families. Hypobromous acid (HOBr), a key species in the linkage of BrOx to ClOx and HOx, is produced by the hydrolysis of BrONO2 on sulfate aerosols, and thus the heterogeneous behavior of HOBr must be understood. We have measured the solubility of HOBr in 45 to 70 percent by weight sulfuric acid solutions. Over the temperature range 208 to 255 K, HOBr is very soluble in sulfuric acid, H(*) = 10(exp 4) to 10(exp 8) M/atm. The solubility is temperature dependent, and our results agree well with those of Waschewsky and Abbott for 60 percent by weight H2SO4. HOBr is nearly as soluble as HBr, indicating that equilibrium concentrations of HOBr could approach those of HBr in sulfuric acid aerosols. Despite the high solubility of HOBr, stratospheric aerosol volumes are not large enough to sequester a significant fraction of inorganic bromine from the gas phase. Uptake of HOBr was nearly always accompanied by reaction, producing Br2O and possibly Br2. The effect of this bromine conversion pathway on the HOx and ClOx families, particularly at temperatures as warm as 255 K, will be considered.

  10. Annual Cycles of Multiyear Sea Ice Coverage of the Arctic Ocean: 1999-2003

    NASA Technical Reports Server (NTRS)

    Kwok, R.

    2004-01-01

    For the years 1999-2003, we estimate the time-varying perennial ice zone (PIZ) coverage and construct the annual cycles of multiyear (MY, including second year) ice coverage of the Arctic Ocean using QuikSCAT backscatter, MY fractions from RADARSAT, and the record of ice export from satellite passive microwave observations. An area balance approach extends the winter MY coverage from QuikSCAT to the remainder of the year. From these estimates, the coverage of MY ice at the beginning of each year is 3774 x 10(exp 3) sq km (2000), 3896 x 10(exp 3) sq km (2001), 4475 x 10(exp 3) sq km (2002), and 4122 x 10(exp 3) sq km (2003). Uncertainties in coverage are approx.150 x 10(exp 3) sq km. In the mean, on 1 January, MY ice covers approx.60% of the Arctic Ocean. Ice export reduces this coverage to approx.55% by 1 May. From the multiple annual cycles, the area of first-year (FY) ice that survives the intervening summers are 1192 x 10(exp 3) sq km (2000), 1509 x 10(exp 3) sq km (2001), and 582 x 10(exp 3) sq km (2002). In order for the MY coverage to remain constant from year to year, these replenishment areas must balance the overall area export and melt during the summer. The effect of the record minimum in Arctic sea ice area during the summer of 2002 is seen in the lowest area of surviving FY ice of the three summers. In addition to the spatial coverage, the location of the PIZ is important. One consequence of the unusual location of the PIZ at the end of the summer of 2002 is the preconditioning for enhanced export of MY ice into the Barents and Kara seas. Differences between the minimums in summer sea ice coverage from our estimates and passive microwave observations are discussed.

  11. Adhesion between Polymers and Evaporated Gold and Nickel Films.

    DTIC Science & Technology

    1984-08-01

    on PTFE, about 5.49x10(exp 6) N/sq m on UHMWPE , and 6.54 x 10(exp 6) N/sq m on 6/6 nylon. The adhesion strengths for nickel films evaporated on PTFE... UHMWPE , and 6/6 nylon were found to be a factor of 1.7 higher than those for the gold-coated PTFE, UHMWPE , and 6/6 nylon. To confirm quantitatively

  12. Detection of high-energy gamma-ray emission from the BL Lacertae object Markarian 421 by the Egret telescope on the Compton Observatory

    NASA Technical Reports Server (NTRS)

    Lin, Y. C.; Bertsch, D. L.; Chiang, J.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Mattox, J. R.

    1992-01-01

    Gamma radiation in the energy range from 50 MeV to well over 1 GeV has been observed from the direction of the BL Lac object Markarian 421 by the Energetic Gamma Ray Experiment Telescope on the Compton Observatory during the period 1991 June 27-July 11. The source flux is weak, but still statistically significant at the level of 10 exp -5; the integrated photon flux above 100 MeV is (1.4 +/- 0.3) x 10 exp -7/sq cm s. The differential photon energy spectrum can be represented by a power law with exponent 1.96 +/- 0.14. This is the first detection of gamma-ray emission from a BL Lac object.

  13. Observation of high-energy gamma rays from the quasi-stellar object CTA 102

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A.

    1993-01-01

    The quasar CTA 102 (QSO 2230 + 114) was observed four times in 1991-1992 by the EGRET high-energy gamma-ray telescope on the Compton GRO satellite. In the 1992 January 23-February 6 observation, emission was detected at the level (2.4 +/- 0.5) x 10 exp 7 photons/sq cm s (E is greater than 100 MeV). The other observations produced upper limits or detections with lower significance which are consistent with the same flux. The photon spectrum can be represented by a power law with a number index of 2.6 +/- 0.2, the softest so far observed by EGRET. The emitted gamma-ray luminosity, if isotropic, is 5 x 10 exp 47 ergs/s (H(0) = 75 km/s Mpc , q(0) = 0.5), although there are good reasons to believe that the gamma emission is strongly beamed.

  14. Diffusion coefficients of energetic water group ions near Comet Giacobini-Zinner

    NASA Astrophysics Data System (ADS)

    Tan, L. C.; Mason, G. M.; Richardson, I. G.; Ipavich, F. M.

    1993-03-01

    Data from the ultralow-energy charge analyzer and energetic particle anisotropy spectrometer sensors, acquired when the ICE spacecraft flew past Comet Giacobini-Zinner on September 11, 1985, are combined, and a single, self-consistent analysis technique is applied to derive a single-particle spectrum from about 200 to 1600 km/s. This information, together with the deduced bulk flow speed of the ions, is used to calculate a parallel diffusion coefficient in the transition region downstream of the bow wave (2.3 +/- 0.5) x 10 exp 17 sq cm/s; the corresponding scattering mean free path is (6 +/- 1) x 10 exp 4 km. The parallel diffusion coefficient is found to depend on the collision frequency of water group ions with Alfven waves, which are assumed to be propagating parallel (antiparallel) to the magnetic field.

  15. Experimental Determination of the Recovery Factor and Analytical Solution of the Conical Flow Field for a 20 deg Included Angle Cone at Mach Numbers of 4.6 and 6.0 and Stagnation Temperatures to 2600 degree R

    NASA Technical Reports Server (NTRS)

    Pfyl, Frank A.; Presley, Leroy L.

    1961-01-01

    The local recovery factor was determined experimentally along the surface of a thin-walled 20 deg included angle cone for Mach numbers near 6.0 at stagnation temperatures between 1200 deg R and 2600 deg R. In addition, a similar cone configuration was tested at Mach numbers near 4.5 at stagnation temperatures of approximately 612 deg R. The local Reynolds number based on flow properties at the edge of the boundary layer ranged between 0.1 x 10(exp 4) and 3.5 x 10(exp 4) for tests at temperatures above 1200 deg R and between 6 x 10(exp 4) and 25 x 10(exp 4) for tests at temperatures near 612 deg R. The results indicated, generally, that the recovery factor can be predicted satisfactorily using the square root of the Prandtl number. No conclusion could be made as to the necessity of evaluating the Prandtl number at a reference temperature given by an empirical equation, as opposed to evaluating the Prandtl number at the wall temperature or static temperature of the gas at the cone surface. For the tests at temperatures above 1200 deg R (indicated herein as the tests conducted in the slip-flow region), two definite trends in the recovery data were observed - one of increasing recovery factor with decreasing stagnation pressure, which was associated with slip-flow effects and one of decreasing recovery factor with increasing temperature. The true cause of the latter trend could not be ascertained, but it was shown that this trend was not appreciably altered by the sources of error of the magnitude considered herein. The real-gas equations of state were used to determine accurately the local stream properties at the outer edge of the boundary layer of the cone. Included in the report, therefore, is a general solution for the conical flow of a real gas using the Beattie-Bridgeman equation of state. The largest effect of temperature was seen to be in the terms which were dependent upon the internal energy of the gas. The pressure and hence the pressure drag terms were

  16. Detection of C2H4 Neptune from ISO/PHT-S Observations

    NASA Technical Reports Server (NTRS)

    Schulz, B.; Encrenaz, Th.; Bezard, B.; Romani, P. N.; Lellouch, E.; Atreya, S. K.

    1999-01-01

    The 6-12 micrometer spectrum of Neptune has been recorded with the PHT-S instrument of the Infrared Space Observatory (ISO) at a resolution of 0.095 micrometer. In addition to the emissions of CH4, CH3D and C2H6 previously identified, the spectrum shows the first firm identification of ethylene C2H4. The inferred column density above the 0.2-mbar level is in the range (1.1 - 3) x 10(exp 14) molecules/cm. To produce this low amount, previous photochemical models invoked rapid mixing between the source and sink regions of C2H4. We show that this requirement can be relaxed if recent laboratory measurements of CH4 photolysis branching ratios at Lyman alpha are used.

  17. Elevated Temperature Deformation of Fe-39.8Al and Fe-15.6Mn-39.4Al

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. Daniel

    2004-01-01

    The elevated temperature compressive properties of binary Fe-39.8 at % Al and Fe-15.6Mn-39.4Al have been measured between 1000 and 1300 K at strain rates between 10(exp 7) and 10(exp 3)/ s. Although the Mn addition to iron aluminide did not change the basic deformation characteristics, the Mn-modified alloy was slightly weaker. In the regime where deformation of FeAl occurs by a high stress exponent mechanism (n = 6), strength increases as the grain size decreases at least for diameters between approx. 200 and approx. 10 microns. Due to the limitation in the grain size-flow stress-temperature-strain rate database, the influence of further reductions of the grain size on strength is uncertain. Based on the appearance of subgrains in deformed iron aluminide, the comparison of grain diameters to expected subgrain sizes, and the grain size exponent and stress exponent calculated from deformation experiments, it is believed that grain size strengthening is the result of an artificial limitation on subgrain size as proposed by Sherby, Klundt and Miller.

  18. OSSE observations of GX 339-4

    NASA Technical Reports Server (NTRS)

    Grabelsky, D. A.; Maltz, S. M.; Purcell, W. R.; Ulmer, M. P.; Grove, J. E.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Jung, G. V.

    1995-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (CGRO) observed the Galactic black hole candidate GX 339-4 as a target of oppurtunity in 1991 September, in response to the outburst reported by Burst and Transient Source Experiment (BATSE). We report here on energy spectra in the 50 keV-10 MeV range obtained by OSSE. The source was detected from 50 to 400 keV at a level relative to the Crab Nebula of approximately 30%. The observed spectrum was prescribed reasonably well by a power law with an exponential cutoff; a least-squares fit yielded a photon index of 0.88 +/- 0.05 and a cutoff energy of 68 +/- 2 keV. The addition of a Compton reflection component did not significantly improve the overall fit. An optically thin thermal bremsstrahlung spectrum also provides a good fit, and the thermal Comptonization model of Sunyaev & Titarchuk, while deficient in describing the data above approximately 200 keV, cannot formally be ruled out. A pure power law with reflection does not fit the observed spectrum. During a follow-up observation made in 1991 November the intensity of the source below 100 keV had dropped by more than a factor of 40, and it was no longer detected above approximately 100 keV. The energy spectrum during the November observation could be characterized by a power law with a photon index of 2.3 +/- 0.3; the spectrum was fitted equally well with the same exponentially cutoff power-law model applied to the September observation, reduced in intensity by a factor of approximately 40. During the 1991 September observation, the luminosity in the 50-400 keV band was approximately 2 x 10(exp 37) ergs/s (assuming a distance of 4 kpc), no more than a factor of 5 below the soft X-ray luminosity of GX 339-4 observed in its X-ray high state. The luminosity during the 1991 November observation was approximately 5 x 10(exp 35) ergs/s. Extrapolations of both the exponentially cutoff power-law and Sunyaev-Titarchuk models to

  19. Planetary wave variability of Sq currents

    NASA Astrophysics Data System (ADS)

    Elhawary, R.; Forbes, J. M.

    2016-11-01

    The E region wind dynamo is a key linkage in atmosphere-ionosphere coupling, but relatively little is known about variability of the corresponding E region currents in terms of connections with atmosphere dynamics. In this paper we analyze ground magnetic variations ΔB during 2009 at two midlatitude stations to reveal planetary wave (PW) periodicities near those of well-known atmospheric normal modes, i.e., 5, 10, and 16 days. In the neutral atmosphere these waves are westward propagating with zonal wave number s = 1. The two stations are at the same magnetic latitude and are nearly conjugate in longitude, which leads to following new insights: First, the amplitude and phase variations between the two stations do not conform to simple westward propagating waves with zonal wave number s = 1, implying that the underlying physics is more complex, in part due to modulation by the predominantly s = 1 longitude-dependent magnetic field. There is also compelling evidence that much ΔB variability near PW periods arises through the product of solar-controlled conductivity and PW-related electric field in the expression for electric current, mainly arising from solar radiation periodicities longer than the solar rotation period. For instance, interactions between solar periodicities in conductivity near 53d and 83d and PW periodicities in total electric field yield secondary peaks in the ΔB spectrum that contribute to its variability at periods less than 20d. In fact, most of the observed ΔB variability arises from these two latter sources, rather than directly from the original driving PW oscillations.

  20. Global Evolution of Solid Matter in Turbulent Protoplanetry Disks. Part 1; Aerodynamics of Solid Particles

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Valageas, P.

    1996-01-01

    The problem of planetary system formation and its subsequent character can only be addressed by studying the global evolution of solid material entrained in gaseous protoplanetary disks. We start to investigate this problem by considering the space-time development of aerodynamic forces that cause solid particles to decouple from the gas. The aim of this work is to demonstrate that only the smallest particles are attached to the gas, or that the radial distribution of the solid matter has no momentary relation to the radial distribution of the gas. We present the illustrative example wherein a gaseous disk of 0.245 solar mass and angular momentum of 5.6 x 10(exp 52) g/sq cm/s is allowed to evolve due to turbulent viscosity characterized by either alpha = 10(exp -2) or alpha = 10(exp -3). The motion of solid particles suspended in a viscously evolving gaseous disk is calculated numerically for particles of different sizes. In addition we calculate the global evolution of single-sized, noncoagulating particles. We find that particles smaller than 0.1 cm move with the gas; larger particles have significant radial velocities relative to the gas. Particles larger than 0.1 cm but smaller than 10(exp 3) cm have inward radial velocities much larger than the gas, whereas particles larger than 10(exp 4) cm have inward velocities much smaller than the gas. A significant difference in the form of the radial distribution of solids and the gas develops with time. It is the radial distribution of solids, rather than the gas, that determines the character of an emerging planetary system.

  1. The 2006-2007 Active Phase Of Anomalous X-Ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts, and Burst Spectral Features

    NASA Technical Reports Server (NTRS)

    Gavril, Fotis P.; Dib, Rim; Kaspi, Victoria M.

    2009-01-01

    After at least 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months and included six X-ray bursts as well as many changes in the persistent X-ray emission. The bursts, the first seen from this AXP in >11 years of Rossi X-ray Timing Explorer monitoring, all occurred in the interval between 2006 April 6 and 2007 February 7. The burst durations ranged from 8-3x10(exp 3)s. The first five burst spectra are well modeled by blackbodies, with temperatures kT approx. 2 - 6 keV. However, the sixth burst had a complicated spectrum that is well characterized by a blackbody plus three emission features whose amplitude varied throughout the burst. The most prominent feature was at 14.0 keV. Upon entry into the active phase the pulsar showed a significant change in pulse morphology and a likely timing glitch. The glitch had a total frequency jump of (1.9+/-0.4)x10(exp -7) Hz, which recovered with a decay time of 17+/-2 days by more than the initial jump, implying a net spin-down of the pulsar. We discuss these events in the context of the magnetar model.

  2. Centrality, rapidity, and transverse-momentum dependence of cold nuclear matter effects on J/psi production in dAu, CuCu, and AuAu collisions at sq root(s{sub NN})=200 GeV

    SciTech Connect

    Ferreiro, E. G.; Fleuret, F.; Rakotozafindrabe, A.

    2010-06-15

    We have carried out a wide study of cold nuclear matter (CNM) effects on J/psi production in dAu, CuCu and AuAu collisions at sq root(s{sub NN})=200 GeV. We have studied the effects of three different gluon-shadowing parametrizations, using the usual simplified kinematics for which the momentum of the gluon recoiling against the J/psi is neglected as well as an exact kinematics for a 2->2 process; namely g+g->J/psi+g as expected from LO pQCD. We have shown that the rapidity distribution of the nuclear modification factor R{sub dAu}, and particularly its antishadowing peak, is systematically shifted toward larger rapidities in the 2->2 kinematics, irrespective of which shadowing parametrization is used. In turn, we have noted differences in the effective final-state nuclear absorption needed to fit the PHENIX dAu data. Taking advantage of our implementation of 2->2 kinematics, we have also computed the transverse momentum dependence of the nuclear modification factor, which cannot be predicted with the usual simplified kinematics. All the corresponding observables have been computed for CuCu and AuAu collisions and compared to the PHENIX and STAR data. Finally, we have extracted the effective nuclear absorption from the recent measurements of R{sub CP} in dAu collisions by the PHENIX collaboration.

  3. The relative importance of prebiotic synthesis on the Earth and input from comets and meteorites

    NASA Technical Reports Server (NTRS)

    Miller, S. L.

    1991-01-01

    The prebiotic synthesis of hydrogen cyanide and formaldehyde was studied by the action of electric discharges on various model primitive atmospheres containing CH4, CO, and CO2. Photochemical production rates would also have been important and were calculated for HCN and H2CO. A reasonable rate of synthesis of amino acids from these sources is about 10 n moles/(sq cm yr) or 0.10 moles/sq cm in 10(exp 7) yrs. This would give a concentration of 3 x 10(exp -4) M in an ocean of the present size (300 liters/sq cm). The amino acids cannot accumulate over a longer period because the entire ocean passes through the 350 C submarine vents in 10(exp 7) yrs, which decomposes all the organic compounds. A number of workers have calculated the influx of comets and meteorites on the primitive earth, both as a destructive process for organic compounds and for any life that was present, as well as a source of organic compounds. Some of the amino acids from the meteorite proposed to have hit the earth 65 x 10(exp 6) yrs ago were detected at the Cretaceous/Tertiary boundary sediments. The problem with proposing a large scale input of organic compounds from meteorites and comets is that they must survive passage through the atmosphere and impact. There are some processes that would allow survival such as showers of centimeter to meter sized meteorites and various aerodynamic braking processes for larger objects. Even if a significant amount of the organic material survived impact, the destructive processes in the hydrothermal vents would remove these compounds on the average in 10(exp 7) yrs or less. If it is assumed that the input rate was sufficient to overcome these destructive processes, then too much carbon and water, especially from comets, would have been added to the surface of the earth. It was concluded that while some organic material was added to the earth from comets and meteorites, the amount available from these sources at a given time was only a few percent of that from

  4. Photochemistry Saturn's Atmosphere. 2; Effects of an Influx of External Oxygen

    NASA Technical Reports Server (NTRS)

    Moses, Julianne I.; Lellouch, Emmanuel; Bezard, Bruno; Gladstone, G. Randall; Allen, Mark

    2000-01-01

    We use a one-dimensional diurnally averaged model of photochemistry and diffusion in Saturn's stratosphere to investigate the influence of extraplanetary debris on atmospheric chemistry. In particular, we consider the effects of an influx of oxygen from micrometeoroid ablation or from ring-particle diffusion; the contribution from cometary impacts, satellite debris, or ring vapor is deemed to be less important. The photochemical model results are compared directly with Infrared Space Observatory (ISO) observations to constrain the influx of extraplanetary oxygen to Saturn. From the ISO observations, we determine that the column densities of CO2 and H2O above 10 mbar in Saturn's atmosphere are (6.3 +/- 1) x 10(exp 14) and (1.4 +/- 0.4) x 10(exp 15)/ square cm, respectively; our models indicate that a globally averaged oxygen influx of (4+/-2) x 10(exp 6) O atoms /sq cm/s is required to explain these observations. Models with a locally enhanced influx of H20 operating over a small fraction of the projected area do not provide as good a fit to the ISO H2O observations. If volatile oxygen compounds comprise one-third to one-half of the exogenic source by mass, then Saturn is currently being bombarded with (3 +/- 2) x 10(exp -16) g/square cm/s of extraplanetary material. To reproduce the observed CO2/H2O ratio in Saturn's stratosphere, some of the exogenic oxygen must arrive in the form of a carbon-oxygen bonded species such as CO or CO2. An influx consistent with the composition of cometary ices fails to reproduce the high observed CO2/H2O ratio, suggesting that (i) the material has ices that are slightly more carbon-rich than is typical for comets, (ii) a contribution from an organic-rich component is required, or (iii) some of the hydrogen-oxygen bonded material is converted to carbon-oxygen bonded material without photochemistry (e.g., during the ablation process). We have also reanalyzed the 5-micron CO observations of Noll and Larson and determine that the CO

  5. Micrometeorological measurements of CH4 and CO2 exchange between the atmosphere and subarctic tundra

    NASA Technical Reports Server (NTRS)

    Fan, S. M.; Wofsy, S. C.; Bakwin, P. S.; Jacob, D. J.; Anderson, S. M.; Kebabian, P. L.; Mcmanus, J. B.; Kolb, C. E.; Fitzjarrald, D. R.

    1992-01-01

    Eddy correlation flux measurements and concentration profiles of total hydrocarbons (THC) and CO2 were combined to provide a comprehensive record of atmosphere-biosphere exchange for these gases over a 30-day period in July-August 1988 in the Yukon-Kuskokwin River Delta of Alaska. Over 90 percent of net ecosystem exchanges of THC were due to methane. Lakes and wet meadow tundra provided the major sources of methane. The average fluxes from lake, dry tundra, and wet tundra were 11 +/- 3, 29 +/- 3, and 57 +/- 6 mg CH4/sq m/d, respectively. The mean remission rate for the site was 25 mg/sq m/d. Maximum uptake of CO2 by the tundra was 1.4 gC/sq m/d between 1000 and 1500 hrs, and nocturnal respiration averaged 0.73 gC/sq m/d. Net uptake of CO2 was 0.30 gC/sq m/d for the 30 days of measurement; methane flux accounted for 6 percent of CO2 net uptake.

  6. A rocket-borne observation of the far-infrared sky at high Galactic latitude

    NASA Technical Reports Server (NTRS)

    Kawada, M.; Bock, J. J.; Hristov, V. V.; Lange, A. E.; Matsuhara, H.; Matsumoto, T.; Matsuura, S.; Mauskopf, P. D.; Richards, P. L.; Tanaka, M.

    1994-01-01

    We have measured the surface brightness of the far-infrared sky at lambda = 134, 154, and 186 micrometers at high Galactic latitude using a liquid-He-cooled, rocket-borne telescope. The telescope scanned over a 5 deg x 20 deg region which includes infrared cirrus, high-latitude molecular clouds, the starburst galaxy M82, and the H I Hole in Ursa Major, a region with uniquely low H I column density. The measured brightness at 134, 154, and 186 micrometers is well correlated with the 100 micrometers brightness measured by IRAS and, in regions excluding molecular clouds, with H I column density. The spectrum of the component correlated with H I is well fitted by a gray-body spectrum with a temperature of 16.4 (+2.3/-1.8) K, assuming an emissivity proportional to lambda(exp -2). Assuming a constant far-infrared dust emissivity per hydrogen nucleus, the ratio of the H2 column density to the velocity-integrated CO intensity in the high-latitude molecular cloud is NH2/W(sub co) = (1.6 +/- 0.3) x 10(exp 20)/sq cm/(K km/s). The residual brightness after subtracting the emission correlated with H I column density is lambda I(sub lambda)(154 micrometers) = (1.4 +/- 0.6) x 10(exp -12) W/sq cm/sr, yielding an upper limit to the far-infrared extragalactic background radiation of lambda I(sub lambda)(154 micrometers) is less than 2.6 x 10(exp -12) W/sq cm/sr.

  7. Search for Compton-backscattered annihilation radiation from the galactic center with the OSSE

    NASA Technical Reports Server (NTRS)

    Smith, D. M.; Leventhal, M.; Gehrels, N.; Tueller, J.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M . S.; Grabelsky, D. A.; Purcell, W. R.

    1995-01-01

    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 approximately 15 deg of the Galactic center (Leventhal, MacCallum, & Stang 1978; Smith et al. 1993). Upper limits on this feature set by HEAO 3 (Mahoney, Ling, & Wheaton 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 bakscatter flux from 1E 1740.7-2942 is 6.8 x 10(exp -4) photons/sq cm/s, compared to the 1.3 x 10(exp -3) photons/sq cm 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, & 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(exp -4) photons/sq cm/s, or approximately 8% of the reported flux.

  8. Pressure sintering of Si3N4-Al2O3 /Sialon/

    NASA Technical Reports Server (NTRS)

    Yeh, H. C.; Sanders, W. A.; Fiyalko Luttner, J. L.

    1977-01-01

    Essentially pore-free Sialon bodies were obtained by pressure sintering for three blends (mol ratios of 4:1, 2:3, and 3:2) of Si3N4 and Al2O3 powders under the conditions of 27.6 MN/sq m and a temperature of 1700 C for 2 h. These dense bodies consist mainly of a Sialon solid solution with a minor amount of a particular second phase. The higher the Al2O3 content (20 to 60 mol% range) in Sialon, the higher the densification rate. Fully dense bodies can be obtained at temperatures as low as 1500 C at 27.6 MN/sq m for 2 h with no second phase detectable by X-ray diffraction. A 100% dense body can be obtained by heating at 1700 C at 27.6 MN/sq m without a holding time.

  9. Evaluation of a far infrared Ge:Ga multiplexed detector array

    NASA Technical Reports Server (NTRS)

    Farhoomand, Jam; Mccreight, Craig

    1990-01-01

    The performance of a multielement Ge:Ga linear array under low-background conditions is investigated. On-focal plane switching is accomplished by MOSFET switches and the integrated charge is made available through MOSFET source followers. The tests were conducted at 106 microns and the radiation on the detectors was confined to a spectral window 1.25 microns wide using a stack of cold filters. At 4.2 K, the responsivity was measured to be nominally 584 A/W, and the NEP was 1.0 x 10 exp -16 W/sq rt Hz. A detailed description of the test setup and the procedure is presented.

  10. EGRET observations of 3C 273

    NASA Technical Reports Server (NTRS)

    Von Montigny, C.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1993-01-01

    The quasar 3C 273 was detected by COS-B in the 1970's. EGRET observations of this sky region in June and October 1991 revealed a flux from 3C 273 lower than that measured by COS-B. The flux observed by EGRET in the June period is approximately 3 x 10 exp -7/sq cm s for energies greater than 100 MeV. During the October observation it appears to be even lower. For the first observation a preliminary spectrum which has a photon index of 2.4 has been derived.

  11. Quantification of HCl from High Resolution Infrared Solar Spectra Obtained at the South Pole in December 1986

    NASA Technical Reports Server (NTRS)

    Goldman, A.; Murcray, F. J.; Murcray, F. H.; Murcray, D. G.

    1987-01-01

    Ground-based infrared solar spectra at 0.02/ cm resolution obtained at the Amundsen-Scott South Pole station in December 1986 have been analysed for the atmospheric content of HCl. Nonlinear least-squares spectral fitting applied to the spectra yields a total HCl column amount of (6.4 +/- 0.8) x 10(exp 15) molec/sq cm, most being stratospheric. This amount is larger than that extrapolated from earlier results on the latitudinal distribution of atmospheric HCl.

  12. One year duration of immunity of the modified live bovine viral diarrhea virus type 1 and type 2 and bovine herpesvirus-1 fractions of Vista® Once SQ vaccine.

    PubMed

    Purtle, Lisa; Mattick, Debra; Schneider, Corey; Smith, Linda; Xue, Wenzhi; Trigo, Emilio

    2016-03-18

    Three studies were performed to determine the duration of immunity of the bovine viral diarrhea virus type 1 and type 2 (BVDV-1 and BVDV-2) and bovine herpesvirus-1 (BHV-1) fractions of a commercially prepared modified-live vaccine. Vista® Once SQ (Vista®) vaccine contains five modified-live viruses, BVDV-1, BVDV-2, BHV-1, bovine respiratory syncytial virus, and bovine parainfluenza 3 virus, and two modified-live bacteria, Pasteurella multocida and Mannheimia haemolytica. For all three studies, calves were administered a single dose of vaccine or placebo vaccine subcutaneously, and were challenged with one of the three virulent viruses at least one year following vaccination. Calves were evaluated daily following challenge for clinical signs of disease associated with viral infection, nasal swab samples were evaluated for virus shedding, and serum was tested for neutralizing antibodies. Following the BVDV-1 and BVDV-2 challenges, whole blood was evaluated for white blood cell counts, and for the BVDV-2 study, whole blood was also evaluated for platelet counts. Calves vaccinated with BVDV type 1a, were protected from challenge with BVDV type 1b, and had significant reductions in clinical disease, fever, leukopenia, and virus shedding compared to control calves. Vaccinated calves in the BVDV-2 study were protected from clinical disease, mortality, fever, leukopenia, thrombocytopenia, and virus shedding compared to controls. Vaccinated calves in the BHV-1 study were protected from clinical disease and fever, and had significantly reduced duration of nasal virus shedding. These three studies demonstrated that a single administration of the Vista® vaccine to healthy calves induces protective immunity against BVDV-1, BVDV-2 and BHV-1 that lasts at least one year following vaccination.

  13. The orbital evolution of real asteroids near the 4:1 mean-motion resonance with Jupiter

    NASA Technical Reports Server (NTRS)

    Dahlgren, Mats; Hahn, Gerhard; Lagerkvist, C.-I.; Lundstroem, M.

    1992-01-01

    Numerical integrations of the orbits of ten asteroids with osculating elements near the 4:1 mean-motion resonance with Jupiter have been performed over 200,000 years into the future. A variety of orbital evolutions was found, depending on the start values of the semi-major axis. The orbit of asteroid 1983 RJ4, which lies almost exactly at the resonance center, experiences large variations in eccentricity, evolving into an Earth-crosser on a time-scale of a few 10(exp 4) years. This makes this region a potential source for Apollo objects and meteoritic material, although the width of the resonance region in semi-major axis seems to be very narrow.

  14. Rate constant for the reaction of OH with CH3CCl2F (HCFC-141b) determined by relative rate measurements with CH4 and CH3CCl3

    NASA Technical Reports Server (NTRS)

    Huder, Karin; Demore, William B.

    1993-01-01

    Determination of accurate rate constants for OH abstraction is of great importance for the calculation of lifetimes for HCFCs and their impact on the atmosphere. For HCFC-141b there has been some disagreement in the literature for absolute measurements of this rate constant. In the present work rate constant ratios for HCFC-141b were measured at atmospheric pressure in the temperature range of 298-358 K, with CH4 and CH3CCl3 as reference gases. Ozone was photolyzed at 254 nm in the presence of water vapor to produce OH radicals. Relative depletions of 141b and the reference gases were measured by FTIR. Arrhenius expressions for 141b were derived from each reference gas and found to be in good agreement with each other. The combined expression for HCFC-141b which we recommend is 1.4 x 10 exp -12 exp(-1630/T) with k at 298 K being 5.9 x 10 exp -15 cu cm/molec-s. This value is in excellent agreement with the JPL 92-20 recommendation.

  15. Aerodynamic Characteristics at Mach Numbers of 1.41 and 2.01 of a Series of Cranked Wings Ranging in Aspect Ratio from 4.00 to 1.74 in Combination with a Body

    NASA Technical Reports Server (NTRS)

    Sevier, John R., Jr.

    1960-01-01

    A program has been conducted in the Langley 4- by 4-foot supersonic pressure tunnel to determine the effects of certain wing plan-form variations on the aerodynamic characteristics of wing-body combinations at supersonic speeds. The present report deals with the results of tests of a family of cranked wing plan forms in combination with an ogive-cylinder body of revolution. Tests were made at Mach numbers of 1.41 and 2.01 at corresponding values of Reynolds number per foot of 3.0 x 10(exp 6) and 2.5 x 10(exp 6). Results of the tests indicate that the best overall characteristics were obtained with the low-aspect-ratio wings. Plan-form changes which involved decreasing the aspect ratio resulted in higher values of maximum lift-drag ratio, in addition to large increases in wing volume. Indications are that this trend would have continued to exist at aspect ratios even lower than the lowest considered in the present tests. Increases in the maximum lift-drag ratio of about 15 percent over the basic wing were achieved with practically no increase in drag. The severe longitudinal stability associated with the basic cranked wing was no longer present (within the limits of the present tests) on the wings of lower aspect ratio formed by sweeping forward the inboard portion of the trailing edge.

  16. Electron-Temperature Dependence of the Recombination of NH4(+)((NH3)(sub n) Ions with Electrons

    NASA Technical Reports Server (NTRS)

    Skrzypkowski, M. P.; Johnson, R.

    1997-01-01

    The two-body recombination of NH4(+)(NH3)(sub 2,3) cluster-ions with electrons has been studied in an afterglow experiment in which the electron temperature T, was elevated by radio-frequency heating from 300 K up to 900 K. The recombination coefficients for the n = 2 and n = 3 cluster ions were found to be equal, alpha(sub 2, sup(2)) = alpha(sub 3, sup(2)) = (4.8 +/- 0.5) x 10(exp - 6)cu cm/s, and to vary with electron temperature as T(sub c, sup -0.65) rather than to be nearly temperature-independent as had been inferred from measurements in microwave-heated plasmas.

  17. 2.4 Micron Cutoff AlGaAsSb/InGaAsSb Phototransistors for Shortwave IR Applications

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Abedin, Nurul; Sulima, Oleg V.; Swaminathan, Krishna; Ismail, Syed; Singh, Upendra N.

    2006-01-01

    Shortwave infrared detectors are critical for several applications including remote sensing and optical communications. Several detectors are commercially available for this wavelength range, but they lack sufficient gain, which limits their detectivity. The characterization results of an AlGaAsSb/InGaAsSb phototransistor for shortwave IR application are reported. The phototransistor is grown using molecular beam epitaxy technique. Spectral response measurements showed a uniform responsivity between 1.2 and 2.4 micron region with a mean value of 1000 A/W. A maximum detectivity of 3.4 X 10(exp 11) cmHz1/2/W was obtained at 2 micron at -20 C and 1.3 V.

  18. X-ray Transients in the Advanced LIGO/Virgo Horizon

    NASA Technical Reports Server (NTRS)

    Kanner, Jonah; Baker, John G.; Blackburn, Lindy L.; Camp, Jordan B.; Mooley, Kunal; Mushotzky, Richard F.; Ptak, Andrew Francis

    2013-01-01

    Advanced LIGO and Advanced Virgo will be all-sky monitors for merging compact objects within a few hundred megaparsecs. Finding the electromagnetic counterparts to these events will require an understanding of the transient sky at low redshift (z < 0.1). We performed a systematic search for extragalactic, low redshift, transient events in the XMM-Newton Slew Survey. In a flux limited sample, we found that highly variable objects comprised 10% of the sample, and that of these, 10% were spatially coincident with cataloged optical galaxies. This led to 4 × 10(exp -4) transients per square degree above a flux threshold of 3×10(exp -12) erg/sq cm/s (0.2-2 keV) which might be confused with LIGO/Virgo counterparts. This represents the first extragalactic measurement of the soft X-ray transient rate within the Advanced LIGO/Virgo horizon. Our search revealed six objects that were spatially coincident with previously cataloged galaxies, lacked evidence for optical active galactic nuclei, displayed high luminosities approx. 10(exp 43) erg/s, and varied in flux by more than a factor of 10 when compared with the ROSAT All-Sky Survey. At least four of these displayed properties consistent with previously observed tidal disruption events.

  19. Micrometeorological measurements of CH[sub 4] and CO[sub 2] exchange between the atmosphere and subarctic tundra

    SciTech Connect

    Fan, S.M.; Wofsy, S.C.; Bakwin, P.S.; Jacob, D.J.; Anderson, S.M.; Kebabian, P.L.; Mcmanus, J.B.; Kolb, C.E.; Fitzjarrald, D.R. Aerodyne Research, Inc., Center for Chemical and Environmental Physics, Billerica, MA New York State Univ., Albany )

    1992-10-01

    Eddy correlation flux measurements and concentration profiles of total hydrocarbons (THC) and CO[sub 2] were combined to provide a comprehensive record of atmosphere-biosphere exchange for these gases over a 30-day period in July-August 1988 in the Yukon-Kuskokwin River Delta of Alaska. Over 90 percent of net ecosystem exchanges of THC were due to methane. Lakes and wet meadow tundra provided the major sources of methane. The average fluxes from lake, dry tundra, and wet tundra were 11 +/- 3, 29 +/- 3, and 57 +/- 6 mg CH4/sq m/d, respectively. The mean remission rate for the site was 25 mg/sq m/d. Maximum uptake of CO[sub 2] by the tundra was 1.4 gC/sq m/d between 1000 and 1500 hrs, and nocturnal respiration averaged 0.73 gC/sq m/d. Net uptake of CO[sub 2] was 0.30 gC/sq m/d for the 30 days of measurement; methane flux accounted for 6 percent of CO2 net uptake. 53 refs.

  20. The National Aeronautics and Space Administration's Gilmore Load Cell Machine: Load Cell Calibrations to 2.22 x 10(exp 7) Newtons

    NASA Technical Reports Server (NTRS)

    Haynes, Michael W.

    2000-01-01

    Designed in 1964 and erected in 1966, the mission of the Gilmore Load Cell Machine was to provide highly accurate calibrations for large capacity load cells in support of NASA's Apollo Program. Still in use today, the Gilmore Machine is a national treasure with no equal.

  1. Fabrication and characterization of high-T(sub c) tapes and coils made from Ag-clad Bi-2223 superconductors

    NASA Astrophysics Data System (ADS)

    Balachandran, U.; Iyer, A. N.; Youngdahl, C. A.; Motowidlo, L. R.; Hoehn, J. G., Jr.; Haldar, P.

    1993-07-01

    Prereacted Pb-doped Bi-Sr-Ca-Cu-O powders were packed into Ag tubes, drawn, rolled, and given intermediate heat treatment to prepare long lengths of Ag-clad Bi-2223 superconductor tapes. With the use of improved process conditions, transport critical current density (J(sub c)) values exceeding 10(exp 5) A/sq cm at 4.2 K and 27 K, and greater than 4 x 10(exp 4) A/sq cm at 77 K, were obtained in zero applied field with short tape samples. Detailed microstructural analysis and J(sub c) measurements in applied fields up to 20 T are reported. Rolled tapes were cut into lengths of up to 10 m, and several such tapes were used in parallel to fabricate small superconducting pancake coils by the 'wind-and-react' technique. Recently, we fabricated a test magnet with six pancake coils, each containing three 10-m lengths of rolled tapes and tested at 4.2, 27, and 77 K as a function of applied fields up to 14.5 T. A maximum generated field of 1.25 T was measured in zero applied field at 4.2 T. Detailed measurements made on the pancake coils and test magnets are reported in this paper.

  2. Development of commercially viable high-T(sub c) Bi-2223 superconductor tapes

    NASA Astrophysics Data System (ADS)

    Balachandran, U.; Youngdahl, C. A.; Haldar, P.; Motowidlo, L. R.

    1993-02-01

    Long lengths of flexible Ag-clad Bi-2223 Superconductors have been fabricated by the powder-in-tube technique using prereacted, poly-phase, Pb-doped Bi-Sr-Ca-Cu-O powders. At the temperature of liquid helium (4.2 K), improved process conditions yielded transport critical current density (J(sub c)) values greater than 10(exp 5) A/sq cm at zero field; at the temperature of liquid nitrogen (77K), the J(sub c) values of short tape samples exceeded 4(10)(exp 4) A/sq cm. Rolled tapes are cut into lengths up to 2 m in length and are used in parallel to fabricate small superconducting pancake coils by the 'wind-and-react' technique. The coils are characterized at 77 K and 4.2 K. The J(sub c) of the coils are up to 80% of the short, rolled sample result at 77 K. The coils exhibited these results even after being cooled and warmed several times between ambient, 77 K, and 4.2 K indicating their stability following thermal cycling.

  3. Swift J2058.4+0516: Discovery of a Possible Second Relativistic Tidal Disruption Flare

    NASA Technical Reports Server (NTRS)

    Cenko, S. Bradely; Krimm, Hans A.; Horesh, Assaf; Rau, Arne; Frail, Dale A.; Kennea, Jamie A.; Levan, Andrew J.; Holland, Stephen T.; Butler, Nathaniel R.; Quimby, Robert M.; Bloom, Joshua S.; Filippenko, Alexei V.; Gal-Yam, Avishay; Greiner, Jochen; Kulkarni, S. R.; Ofek, Eran O.; Olivares, Felipe E.; Schady, Patricia; Silverman, Jeffrey M.; Tanvir, Nial R.; Xu, Dong

    2011-01-01

    We report the discovery by the Swift hard X-ray monitor of the transient source Swift J2058.4+0516 (Sw J2058+05). Our multi-wavelength follow-up campaign uncovered a long-lived (duration approximately greater than months), luminous X-ray (L(sub x.iso) approximates 3 X 10(exp47) erg/s) and radio (vL(sub v.iso) approximates 10(exp 42) erg/s) counterpart. The associated optical emission, however, from which we measure a redshift of 1.1853, is relatively faint, and this is not due to a large amount of dust extinction in the host galaxy. Based on numerous similarities with the recently discovered GRB 110328A / Swift 1164449.3+573451 (Sw 11644+57), we suggest that Sw J2058+05 may be the second member of a new class of relativistic outbursts resulting from the tidal disruption of a star by a supermassive black hole. If so, the relative rarity of these sources implies that either these outflows are extremely narrowly collimated (theta < 1 deg), or only a small fraction of tidal disruptions generate relativistic ejecta. Analogous to the case of long duration gamma-ray bursts and core-collapse supernovae, we speculate that the spin of the black hole may be a necessary condition to generate the relativistic component. Alternatively, if powered by gas accretion (i.e., an active galactic nucleus), this would imply that some galaxies can transition from apparent quiescence to a radiatively efficient state of accretion on quite short time scales.

  4. Search for X-Ray Emission Associated with the Shapley Supercluster with Suzaku

    NASA Technical Reports Server (NTRS)

    Mitsuishi, Ikuyuki; Gupta, Anjali; Yamasaki, Noriko Y.; Takei, Yoh; Ohashi, Takaya; Sato, Kosuke; Galeazzi, Massimiliano; Henry, J. Patrick; Kelley, Richard L.

    2012-01-01

    Suzaku performed observations of 3 regions in and around the Shapley supercluster: a region located between A3558 and A3556, at approx 0.9 times the virial radii of both clusters, and two other regions at 1 deg and 4 away from the first pointing. The 4 deg -otfset observation was used to evaluate the Galactic foreground emission. We did not detect significant redshifted Oxygen emission lines (O VII and O VIII) in the spectra of all three pointings, after subtracting the contribution of foreground and background emission. An upper limit for the redshifted O VIII Ka line intensity of the warm-hot intergalactic medium (WHIM) is 1.5 x 10(exp -7) photons / s / sq cm / sq arcmin, which corresponds to an overdensity of approx 380 (Z/0.1 Solar Z)(exp -1/2)(L/3 Mpc)(exp -1/2), assuming T = 3 x 10(exp 6) K. We found excess continuum emission in the 1 deg-offset and on-filament regions, represented by thermal models with kT approximates 1 keV and approximates 2 keV, respectively. The redshifts of both 0 and that of the supercluster (0.048) are consistent with the observed spectra. The approx 1 keV emission can be also fitted with Ne-rich Galactic (zero redshift) thin thermal emission. Radial intensity profile of 2 keV component suggests contribution from A3558 and A3556, but with significant steepening of the intensity slope in the outer region of A3558. Finally, we summarized the previous Suzaku search for the WHIM and discussed the feasibility of constraining the WHIM. An overdensity of <400 can be detectable using O VII and O VIII emission lines in a range of 1.4 x 10(exp 6) K < T < 5 x 10(exp 6) K or a continuum emission in a relatively high temperature range T > 5 x 10 (exp 6) K with the Suzaku XIS. The non detection with Suzaku suggests that typical line-of-sight average overdensity is < 400.

  5. Five years of Project META - An all-sky narrow-band radio search for extraterrestrial signals

    NASA Technical Reports Server (NTRS)

    Horowitz, Paul; Sagan, Carl

    1993-01-01

    We have conducted a five-year search of the northern sky (delta between 30 and 60 deg) for narrow-band radio signals near the 1420 MHz line of neutral hydrogen, and its second harmonic, using an 8.4 x 10 exp 6 channel Fourier spectrometer of 0.05 Hz resolution and 400 kHz instantaneous bandwidth. The observing frequency was corrected both for motions with respect to three astronomical inertial frames, and for the effect of Earth's rotation, which provides a characteristic changing Doppler signature for narrow-band signals of extraterrestrial origin. Among the 6 x 10 exp 13 spectral channels searched, we have found 37 candidate events exceeding the average detection threshold of 1.7 x 10 exp -23 W/sq m, none of which was detected upon reobservation. The strongest of these appear to be dominated by rare processor errors. However, the strongest signals that survive culling for terrestrial interference lie in or near the Galactic plane. We describe the search and candidate events, and set limits on the prevalence of supercivilizations transmitting Doppler-precompensated beacons at H I or its second harmonic. We conclude with recommendations for future searches, based upon these findings, and a description of our next-generation search system.

  6. The State and Future of Mars Polar Science and Exploration

    NASA Technical Reports Server (NTRS)

    Clifford, Stephen M.; Crisp, David; Fisher, David A.; Herkenhoff, Ken E.; Smrekar, Suzanne E.; Thomas, Peter C.; Wynn-Williams, David D.; Zurek, Richard W.; Barnes, Jeffrey R.; Bills, Bruce G.

    2000-01-01

    As the planet's principal cold traps, the martian polar regions have accumulated extensive mantles of ice and dust that cover individual areas of approx. 10(exp 6)sq km and total as much as 3-4 km thick. From the scarcity of superposed craters on their surface, these layered deposits are thought to he comparatively young-preserving a record of the seasonal and climatic cycling of atmospheric CO2, H2O, and dust over the past approx. 10(exp 5)-10(exp 8) years. For this reason, the martian polar deposits may serve as a Rosetta Stone for understanding the geologic and climatic history of the planet-documenting variations in insolation (due to quasiperiodic oscillations in the planet's obliquity and orbital elements), volatile mass balance, atmospheric composition, dust storm activity, volcanic eruptions, large impacts, catastrophic floods, solar luminosity, supernovae, and perhaps even a record of microbial life. Beyond their scientific value, the polar regions may soon prove important for another reason-providing a valuable and accessible reservoir of water to support the long-term human exploration of Mars. In this paper we assess the current state of Mars polar research, identify the key questions that motivate the exploration of the polar regions, discuss the extent to which current missions will address these questions, and speculate about what additional capabilities and investigations may be required to address the issues that remain outstanding.

  7. The formation of protostellar disks. I - 1 M(solar)

    NASA Technical Reports Server (NTRS)

    Yorke, Harold W.; Bodenheimer, Peter; Laughlin, Gregory

    1993-01-01

    Hydrodynamical calculations of the collapse of an axisymmetric, rotating one solar mass protostellar cloud, including the effects of radiative transfer and radiative acceleration but without magnetic fields, are presented. The results include calculations of infrared protostellar spectra as a function of time and viewing angle. A numerical algorithm involving explicit nested grids is used to resolve the region of initial disk formation and at the same time to include the outer regions in the calculation. The central part of the protostar is modeled approximately. Initial conditions are systematically varied to investigate their influence on the evolution and final configuration of central star plus circumstellar disk. The initial state for the standard case is a centrally condensed molecular cloud core of one solar mass with a mean density of 8 x 10 exp -18 g/cu cm and a specific angular momentum at the outer edge of 7 x 10 exp 20 sq cm/s. The collapse is followed for 8 x 10 exp 4 yr, at which point 0.45 solar mass is contained in a rapidly rotating central object and most of the remainder in a surrounding equilibrium disk. The stability of this final structure is qualitatively analyzed.

  8. Baryonic Content in the Warm-Hot IGM at Low Redshift

    NASA Technical Reports Server (NTRS)

    Sonneborn, George; Shull, M.; Danforth, C.; Moos, W.

    2007-01-01

    Baryons are 4.5% of the universe's mass/energy density; only 10% of these are in stars, galaxies, and clusters. At low-redshift 90% of baryons are in the IGM, 30% in Ly-alpha forest, but most are in hot gas (10(exp 5-7) K) produced by shocks during structure formation. O VI 1032-38 A are the best tracers of this gas. The distribution of O VI absorbers observed by FUSE rises as N(sup -2+/-0.2, down to 10(exp 13)/sq cm. Integrated to logN=13, 7% of baryons reside in the O VI-bearing IGM at 10% solar metallicity, T approx. 10(exp 5.5) K. At redshift z<0.1 metals have been transported less than 800/h kpc from L* galaxies and 200/h kpc from 0.1 L* galaxies. The steepness of dN/dz means that low-N absorbers contribute an equal mass of hot IGM as higher N gas. The total mass of O VI-bearing gas in the IGM depends on determining the turnover in dN/dz at low N(O VI). Future observations by FUSE are needed to reach lower N and to reduce the uncertainty in the dN/dz power law.

  9. Dynamical Model for the Zodiacal Cloud and Sporadic Meteors

    NASA Technical Reports Server (NTRS)

    Nesvorny, David; Janches, Diego; Vokrouhlicky, David; Pokorny, Petr; Bottke, William F.; Jenniskens, Peter

    2011-01-01

    The solar system is dusty, and would become dustier over time as asteroids collide and comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the solar system by Jupiter, thermally destroyed near the Sun, or physically disrupted by collisions. Also, some are swept by the Earth (and other planets), producing meteors. Here we develop a dynamical model for the solar system meteoroids and use it to explain meteor radar observations. We find that the Jupiter Family Comets (JFCs) are the main source of the prominent concentrations of meteors arriving to the Earth from the helion and antihelion directions. To match the radiant and orbit distributions, as measured by the Canadian Meteor Orbit Radar (CMOR) and Advanced Meteor Orbit Radar (AMOR), our model implies that comets, and JFCs in particular, must frequently disintegrate when reaching orbits with low perihelion distance. Also, the collisional lifetimes of millimeter particles may be longer (approx. > 10(exp 5) yr at 1 AU) than postulated in the standard collisional models (approx 10(exp 4) yr at 1 AU), perhaps because these chondrule-sized meteoroids are stronger than thought before. Using observations of the Infrared Astronomical Satellite (IRAS) to calibrate the model, we find that the total cross section and mass of small meteoroids in the inner solar system are (1.7-3.5) 10(exp 11) sq km and approx. 4 10(exp 19) g, respectively, in a good agreement with previous studies. The mass input required to keep the Zodiacal Cloud (ZC) in a steady state is estimated to be approx. 10(exp 4)-10(exp 5) kg/s. The input is up to approx 10 times larger than found previously, mainly because particles released closer to the Sun have shorter collisional lifetimes, and need to be supplied at a faster rate. The total mass accreted by the Earth in particles between diameters D = 5 micron and 1 cm is found to be approx 15,000 tons/yr (factor of 2 uncertainty), which is

  10. Tunable CW diode-pumped Tm,Ho:YLiF4 laser operating at or near room temperature

    NASA Technical Reports Server (NTRS)

    Mcguckin, Brendan T. (Inventor); Menzies, Robert T. (Inventor)

    1995-01-01

    A conversion efficiency of 42% and slope efficiency of 60% relative to absorbed pump power are obtained from a continuous wave diode-pumped Tm,Ho:YLiF4 laser at 2 microns with output power of 84 mW at a crystal temperature of 275 K. The emission spectrum is etalon tunable over a range of7 nm (16.3/cm) centered on 2.067 microns with fine tuning capability of the transition frequency with crystal temperature at a measured rate of -0.03/(cm)K. The effective emission cross-section is measured to be 5 x 10(exp -21) cm squared. These and other aspects of the laser performance are disclosed in the context of calculated atmospheric absorption characteristics in this spectral region and potential use in remote sensing applications. Single frequency output and frequency stabilization are achieved using an intracavity etalon in conjunction with an external reference etalon.

  11. Evidence of a new phase formation (BaTi4O9) by barium implantation into TiO2

    NASA Astrophysics Data System (ADS)

    Ramos, S. M. M.; Bonardi, N.; Brenier, R.; Canut, B.; Thevenard, P.; Brunel, M.

    1994-10-01

    Barium ions of 140 keV energy were implanted at room temperature in TiO2 (rutile) with a fluence of 10(exp 17) ions cm(exp -2). Isochronal heat treatments were carried out in air at 1000, 1100 and 1150 C for 1 h. Rutherford backscattering spectrometry (RBS) in channeling geometry, X-ray diffraction at glancing incidence and X-ray photoemission spectroscopy (XPS) were undertaken to the physico-chemical characterization of the implanted rutile. The annealing at 1150 C leads to the formation of a new phase which have been identified as BaTi4O9 with an average grain size of about 28 nm.

  12. High-Field Fast-Risetime Pulse Failures in 4H- and 6H-SiC pn Junction Diodes

    NASA Technical Reports Server (NTRS)

    Neudeck, Philip G.; Fazi, Christian

    1996-01-01

    We report the observation of anomalous reverse breakdown behavior in moderately doped (2-3 x 10(exp 17 cm(exp -3)) small-area micropipe-free 4H- and 6H-SiC pn junction diodes. When measured with a curve tracer, the diodes consistently exhibited very low reverse leakage currents and sharp repeatable breakdown knees in the range of 140-150 V. However, when subjected to single-shot reverse bias pulses (200 ns pulsewidth, 1 ns risetime), the diodes failed catastrophically at pulse voltages of less than 100 V. We propose a possible mechanism for this anomalous reduction in pulsed breakdown voltage relative to dc breakdown voltage. This instability must be removed so that SiC high-field devices can operate with the same high reliability as silicon power devices.

  13. A Novel Tungsten-Nickel Alloy Ohmic Contact to SiC at 900 C

    NASA Technical Reports Server (NTRS)

    Okojie, Robert S.; Evans, Laura J.; Lukco, Dorothy; Morris, Joseph P.

    2010-01-01

    A novel tungsten-nickel ohmic contact metallization on 4H-SiC and 6H-SiC capable of surviving temperatures as high as 900 C is reported. Preliminary results revealed the following: 1) ohmic contact on n-type 4H-SiC having net doping levels (Nd's) of 1.4 and 2 x 10(exp 19) per cubic centimeter, with specific contact resistances rhosNd's of 7.69 x 10(exp -4) and 5.81 x 10(exp -4) OMEGA (raised dot) square centimeters, respectively, after rapid thermal annealing (RTA), and 5.9 x 10(exp -3) and 2.51 x 10(exp -4) OMEGA (raised dot) square centimeters, respectively, after subsequent soak at 900 C for 1 h in argon, and 2) ohmic contact on n- and p-type 6H-SiC having Nd > 2 x 10(exp 19) and Na > 1 x 10(exp 20) per cubic centimeter, with rhosNd = 5 x 10(exp -5) and rhosNa = 2 X 10(exp -4) OMEGA (raised dot) square centimeter, respectively, after RTA, and rhosNd = 2.5 x 10 (exp -5) and rhosNa = 1.5 x 10(exp -4) OMEGA (raised dot) square centimeter after subsequent treatment at 900 C for 1 h in argon, respectively.

  14. Pyrolysis of vegetation by brief intense irradiation

    SciTech Connect

    Fendell, F.E.; Kung, E.Y. )

    1993-09-01

    When nonreflected intense visible radiation of about 4 x 10 exp 6 J/(sq m-sec) is incident on a dense vegetative layer (about 3-kg/sq m loading, 0.3-m height) for even a second or two, the absorbing leafy matter can be desiccated and gasified. Simple unsteady 1D models are formulated and solved to characterize the rate of propagation earthward of the pyrolysis front, at which the vegetative population under consideration totally disappears. Distinct treatments are undertaken for temperate-cereal-like layers which contain only foliage (hay, wheat, grass) and brush-like layers, in which not only effectively pyrolyzable leafy matter but also partially pyrolyzable woody-stem matter exist. Qualitative remarks consider soot formation in the pyrolyzate and/or combustion of the hydrocarbon-vapor pyrolyzate with interstitial air. 7 refs.

  15. Single Event Effects Test Results for the Actel ProASIC Plus and Altera Stratix-II Field Programmable Gate Arrays

    NASA Technical Reports Server (NTRS)

    Allen, Gregory R.; Swift, Gary M.

    2006-01-01

    This work describes radiation testing of Actel's ProASIC Plus and Altera's Stratix-II FPGAs. The Actel Device Under Test (DUT) was a ProASIC Plus APA300-PQ208 nonvolatile, field reprogrammable device which is based on a 0.22micron flash-based LVCMOS technology. Limited investigation has taken place into flash based FPGA technologies, therefore this test served as a preliminary reference point for various SEE behaviors. The Altera DUT was a Stratix-II EP2S60F1020C4. Single Event Upset (SEU) and Single Event Latchup (SEL) were the focus of these studies. For the Actel, a latchup test was done at an effective LET of 75.0 MeV-sq cm/mg at room temperature, and no latchup was detected when irradiated to a total fluence of 1 x 10(exp 7) particles/sq cm. The Altera part was shown to latchup at room temperature.

  16. New insights into nonradiative heating in late A star chromospheres

    NASA Technical Reports Server (NTRS)

    Walter, Frederick M.; Matthews, Lynn D.; Linsky, Jeffrey L.

    1995-01-01

    Using new and archival spectra from the Goddard High Resolution Spectrograph, we have searched for evidence of chromospheric and transition region emission in six stars of mid to late A spectral type. Two of the stars, alpha Aq1 (A7 IV-V) and alpha Cep (A7 IV-V), show emission in the C II 1335 A doublet, confirming the presence of hot plasma with temperatures comparable to that of the solar transition region. Using radiative equilibrium photospheric models, we estimate the net surface fluxes in the CII emission line to be 9.4 x 10(exp 4) ergs/sq cm/s for alpha Aq1 and 6.5 x 10(exp 4)ergs/sq cm/s for alpha Cep. These are comparable to fluxes observed in stars as hot as approximately 8000 K (B-V = 0.22). We find no evidence for the blueshifted emission reported by Simon et al. (1994). We estimate the basal flux level to be about 30% of that seen in early F stars, and that the bulk of the emission is not basal in origin. We conclude that the basal flux level drops rapidly for B-V approximately less than 0.3, but that magnetic activity may persist to B-v as small as 0.22.

  17. Low Luminosity States of the Black Hole Candidate GX 339-4. 1; ASCA and Simultaneous Radio/RXTE Observations

    NASA Technical Reports Server (NTRS)

    Wilms, Joern; Nowak, Michael A.; Dove, James B.; Fender, Robert P.; DiMatteo, Tiziana

    1998-01-01

    We discuss a series of observations of the black hole candidate GX 339-4 in low luminosity, spectrally hard states. We present spectral analysis of three separate archival Advanced Satellite for Cosmology and Astrophysics (ASCA) data sets and eight separate Rossi X-ray Timing Explorer (RXTE) data sets. Three of the RXTE observations were strictly simultaneous with 843 Mega Hertz and 8.3-9.1 Giga Hertz radio observations. All of these observations have (3-9 keV) flux approximately less than 10(exp-9) ergs s(exp-1) CM(exp -2). The ASCA data show evidence for an approximately 6.4 keV Fe line with equivalent width approximately 40 eV, as well as evidence for a soft excess that is well-modeled by a power law plus a multicolor blackbody spectrum with peak temperature approximately equals 150-200 eV. The RXTE data sets also show evidence of an Fe line with equivalent widths approximately equal to 20-1OO eV. Reflection models show a hardening of the RXTE spectra with decreasing X-ray flux; however, these models do not exhibit evidence of a correlation between the photon index of the incident power law flux and the solid angle subtended by the reflector. 'Sphere+disk' Comptonization models and Advection Dominated Accretion Flow (ADAF) models also provide reasonable descriptions of the RXTE data. The former models yield coronal temperatures in the range 20-50 keV and optical depths of r approximately equal to 3. The model fits to the X-ray data, however, do not simultaneously explain the observed radio properties. The most likely source of the radio flux is synchrotron emission from an extended outflow of extent greater than O(10 (exp7) GM/c2).

  18. Determining the Composition of the Vela Pulsar's Jet

    NASA Technical Reports Server (NTRS)

    Ogelman, Hakki

    1997-01-01

    The pulsar jet is significant in explaining how the Vela pulsar's rotational energy is transported outward to the rest of the SNR, since direct radiation from the pulsar only accounts for a small percentage of the total power. Our previous ROSAT observations presented the first evidence that the pulsar is driving a narrow, collimated, and remarkably symmetrical jet into the SNR (Markwardt, C. and Oegelman, H., 1995, Nature, 375, p. 40) which we interpret to be from a 'cocoon' of hot gas surrounding the jet itself. We obtained an ASCA exposure of the jet in order to determine whether the spectrum is thermal or power-law continuum. The jet cocoon is detected with ASCA at approximately 2-3 x 10(exp -3) ct/s. The X-ray spectrum of the jet is remarkably similar to the surrounding supernova remnant spectrum and extends to X-ray energies of at least 7 keV, with a total flux of approximately 2 x 10(exp -13) erg/s sq cm sq arcmin. The only strong emission line is from He-like Neon at approx. 0.9 keV; otherwise the spectrum is quite smooth. The spectrum cannot be fit by any one standard plasma emission model, so we used models with two-components. The lower energy component is thermal and has a temperature of 0.29 +/- 0.03 keV; the higher energy portion can either be fit by a thermal component of temperature approx. 4 keV or a power law with photon index approx. 2.0. If the observed spectrum is of a 'traditional' jet cocoon, then we estimate the speed of the jet to be at least 800 km/s, depending on the angle of inclination of the jet axis to our line of sight. The mechanical power driving the jet is greater than or equal to 10(exp 36) erg/s which is comparable to the pulsar's spin-down luminosity of 7 x 10(exp 36) erg/s. and the mass flow rate at the head is greater than or equal to 10(exp -6) solar radius/yr. We conclude that the jet must be entraining material all along its length in order to generate such a large mass flow rate.

  19. Viscoelastic Response of the Titanium Alloy Ti-6-4: Experimental Identification of Time- and Rate-Dependent Reversible and Irreversible Deformation Regions

    NASA Technical Reports Server (NTRS)

    Lerch, Bradley A.; Arnold, Steven M.

    2014-01-01

    In support of an effort on damage prognosis, the viscoelastic behavior of Ti-6Al-4V (Ti-6-4) was investigated. This report documents the experimental characterization of this titanium alloy. Various uniaxial tests were conducted to low load levels over the temperature range of 20 to 538 C to define tensile, creep, and relaxation behavior. A range of strain rates (6x10(exp -7) to 0.001/s) were used to document rate effects. All tests were designed to include an unloading portion, followed by a hold time at temperature to allow recovery to occur either at zero stress or strain. The titanium alloy was found to exhibit viscoelastic behavior below the "yield" point and over the entire range of temperatures (although at lower temperatures the magnitude is extremely small). These experimental data will be used for future characterization of a viscoelastic model.

  20. EGRET detection of high-energy gamma radiation from the OVV quasar 3C 454.3

    NASA Technical Reports Server (NTRS)

    Hartman, R. C.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A.

    1993-01-01

    High-energy gamma radiation has been observed from the optically violent variable quasar 3C 454.3 (PKS 2251 + 158) by the Energetic Gamma-Ray Experiment Telescope on the Compton Observatory. During the 1992 January-February observation, the emission showed a power-law photon spectrum with an exponent of -2.18 +/- 0.08. The flux density (greater than 100 MeV) was observed to vary within the range (0.4-1.4) x 10 exp -6 photon/sq cm s on a time scale of less than a week. Lower sensitivity observations during 1992 April and May also detected emission within that range, but with lower statistical significance. An earlier low-sensitivity exposure during 1991 August gave a 95 percent confidence upper limit of 0.26 x 10 exp 6 photon/sq cm s. The similarity of the gamma-ray emission of 3C 454.3 to that of 3C 279 parallels the similarity of these two objects at lower frequencies.

  1. OSSE observations of Galactic 511 keV positron annihilation radiation - Initial phase 1 results. [Oriented Scintillation Spectrometer Experiment

    NASA Technical Reports Server (NTRS)

    Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Jung, G. V.

    1993-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory (GRO) has performed numerous observations of the Galactic plane and Galactic center region to measure the distribution of Galactic 511 keV positron annihilation radiation and to search for time variability of the emission. The initial 511 keV line fluxes for the observations performed during the first 18 months of the GRO mission are presented. The 511 keV line flux for a typical Galactic center observation is (2.5 +/- 0.3) x 10 exp -4 gamma/sq cm per sec, where the quoted uncertainty represents the 1 sigma statistical uncertainty. No statistically significant time variability of the line flux has been observed; the 3 sigma upper limit to daily variations from the mean is 3 x 10 exp -4 gamma/sq cm per sec. The distribution of Galactic 511 keV positron annihilation radiation implied by the OSSE observations is discussed and compared with observations by other instruments.

  2. High Electron Mobility SiGe/Si Transistor Structures on Sapphire Substrates

    NASA Technical Reports Server (NTRS)

    Alterovitz, Samuel A.; Mueller, Carl H.; Croke, Edward T.; Ponchak, George E.

    2003-01-01

    SiGe/Si n-type modulation doped field effect structures and transistors (n-MODFETs) have been fabricated on r-plane sapphire substrates. The structures were deposited using molecular beam epitaxy, and antimony dopants were incorporated via a delta doping process. Secondary ion mass spectroscopy (SIMS) indicates that the peak antimony, concentration was approximately 4 x 10(exp19) per cubic cm. The electron mobility was over 1,200 and 13,000 sq cm/V-sec at room temperature and 0.25 K, respectively. At these two temperatures, the electron carrier densities were 1.6 and 1.33 x 10(exp 12) per sq cm, thus demonstrating that carrier confinement was excellent. Shubnikov-de Haas oscillations were observed at 0.25 K, thus confirming the two-dimensional nature of the carriers. Transistors, with gate lengths varying from 1 micron to 5 microns, were fabricated using these structures and dc characterization was performed at room temperature. The saturated drain current region extended over a wide source-to-drain voltage (V(sub DS)) range, with (V(sub DS)) knee voltages of approximately 0.5 V and increased leakage starting at voltages slightly higher than 4 V.

  3. Observing stellar coronae with the Goddard High Resolution Spectrograph. 1: The dMe star AU microscopoii

    NASA Technical Reports Server (NTRS)

    Maran, S. P.; Robinson, R. D.; Shore, S. N.; Brosius, J. W.; Carpenter, K. G.; Woodgate, B. E.; Linsky, J. L.; Brown, A.; Byrne, P. B.; Kundu, M. R.

    1994-01-01

    We report on an observation of AU Mic taken with the Goddard High Resolution Spectrograph (GHRS) aboard the Hubble Space Telescope. The data consist of a rapid sequence of spectra covering the wavelength range 1345-1375 A with a spectral resolution of 10,000. The observations were originally intended to search for spectral variations during flares. No flares were detected during the 3.5 hr of monitoring. A method of reducing the noise while combining the individual spectra in the time series is described which resulted in the elimination of half of the noise while rejecting only a small fraction of the stellar signal. The resultant spectrum was of sufficient quality to allow the detection of emission lines with an integrated flux of 10(exp -15) ergs/sq cm(sec) or greater. Lines of C I, O I, O V, Cl I, and Fe XXI were detected. This is the first indisputable detection of the 1354 A Fe XXI line, formed at T approximately = 10(exp 7) K, on a star other than the Sun. The line was well resolved and displayed no significant bulk motions or profile asymmetry. From the upper limit on the observed line width, we derive an upper limit of 38 km/s for the turbulent velocity in the 10(exp 7) K plasma. An upper limit is derived for the flux of the 1349 A Fe XII line, formed at T approximately = 1.3 x 10(exp 6) K. These data are combined with contemporaneous GHRS and International Ultraviolet Explorer (IUE) data to derive the volume emission measure distribution of AU Mic over the temperature range 10(exp 4)-10(exp 7) K. Models of coronal loops in hydrostatic equilibrium are consistent with the observed volume emission measures of the coronal lines. The fraction of the stellar surface covered by the footprints of the loops depends upon the loop length and is less than 14% for lengths smaller than the stellar radius. From the upper limit to the estimated width of the Fe XXI line prfile we find that the we cannot rule out Alfven wave dissipation as a possible contributor to the

  4. The lunar environment and its effect on optical astronomy

    NASA Technical Reports Server (NTRS)

    Taylor, G. Jeffrey

    1992-01-01

    The Moon's geologic environment features: (1) gravity field one-sixth that of Earth; (2) sidereal rotation period of 27.3 days; (3) surface with greater curvature than Earth's surface (a chord along a 10 km baseline would have a bulge of 7.2 m); (4) seismically and tidally stable platform on which to make astronomical observations (most moonquakes have magnitudes of 1 to 2 on the Richter scale, within the earth's seismic noise, resulting in ground motions only 1 nm); (5) tenuous atmosphere (the total mass at night is only 10(exp 4) kg) that has an optical depth of 10(exp -6) and does not cause wind induced stresses and vibrations on structures; (6) large diurnal temperature variation (100 to 385 K in equatorial regions), which telescopes must be designed to withstand; (7) weak magnetic field, ranging from 3 to 330 x 10(exp -9) T, compared to 3 x 10(exp -5) T on Earth at the equator; (8) surface exposed to radiation, the most dangerous of which are high energy (1 to 100 Mev) particles resulting from solar flares; (9) high flux of micrometeorites which are not slowed down from their cosmic velocities because of the lack of air (data indicate that microcraters greater than 10 microns across will form at the rate of 3000/sq m/yr); (10) regolith 2 to 30 m thick which blankets the entire lunar surface (this layer is fine-grained (average grain sizes range from 40 to 268 microns), has a low density (800 to 1000 kg/cu m in the upper few mm, rising to 1500 to 1800 kg/cu m at depths of 10 to 20 cm), is porous (35 to 45 pct), cohesive (0.1 to 1.0 kN/sq m), and has a low thermal diffusivity (0.7 to 1.0 x 110-8 sq m/sec); about 29 pct of the regolith is less than 20 micron in size (this dust could pose a hazard to optical telescopes); (11) rubbly upper several hundred meters in which intact bedrock is uncommon, especially in the lunar highlands; and (12) craters with diameter-to-depth ratios of 5 if fresh and less than km across (larger and eroded craters have diameter

  5. SMM observations of gamma-ray transients. 3: A search for a broadened, redshifted positron annihilation line from the direction of the Galactic center

    NASA Technical Reports Server (NTRS)

    Harris, Michael J.; Share, Gerald H.; Leising, Mark D.

    1994-01-01

    We have searched for 1980-1988 Solar Maximum Mission gamma-ray spectrometer data for transient emission on timescales from hours to approximately 12 days of broad gamma-ray lines at energies approximately 400 keV, which were reported by the High Energy Astronomy Observatory (HEAO) 1 and SIGMA experiments from two sources lying toward the Galactic center. The lines have been interpreted as the product of the annihilation of positrons in pair plasmas surrounding the black hole candidate 1E 1740.7-2942 and the X-ray binary 1H 1822-371. Our results from a combined exposure of approximately 1.5 x 10(exp 7)s provide no convincing evidence for transient emission of this line on any timescale between approximately 9 hr and approximately 1 yr. Our 3 sigma upper limits on the line flux during approximately 12 day intervals are characteristically 4.8 x 10(exp -3) photon/sq cm/s, while for approximately 1 day intervals our 3 sigma upper limits are characteristically 4.9 x 10(exp -3) photon/sq cm/s. These results imply a duty cycle of less than 1.3% for the transient line measured from 1H 1822-371 during a approximately 3 week interval in 1977 by HEAO 1, and a duty cycle of less than or = 0.8% for the transient line detected in 1990 and 1992 from 1E 1740.7-2942 on approximately 1 day timescales by SIGMA.

  6. Lysophosphatidic acid receptor 4 signaling potentially modulates malignant behavior in human head and neck squamous cell carcinoma cells

    PubMed Central

    MATAYOSHI, SEN; CHIBA, SHUNMEI; LIN, YANFUI; ARAKAKI, KAZUNARI; MATSUMOTO, HIROFUMI; NAKANISHI, TAKAYA; SUZUKI, MIKIO; KATO, SEIYA

    2013-01-01

    Head and neck squamous cell carcinoma (HNSCC) is the sixth most common non-skin cancer worldwide. Despite improvement in therapeutic strategies, the prognosis of advanced HNSCC remains poor. The extacellular lipid mediators known as lysophosphatidic acids (LPAs) have been implicated in tumorigenesis of HNSCC. LPAs activate G-protein-coupled receptors not only in the endothelial differentiation gene (Edg) family (LPA1, LPA2, LPA3) but also in the phylogenetically distant non-Edg family (LPA4, LPA5, LPA6). The distinct roles of these receptor isoforms in HNSCC tumorigenesis have not been clarified. In the present study, we investigated the effect of ectopic expression of LPA4 in SQ-20B, an HNSCC cell line, expressing a trivial level of endogenous LPA4. LPA (18:1) stimulated proliferation of SQ-20B cells, but did not affect proliferation of HEp-2, an SCC cell line expressing higher levels of LPA4, comparable to those of with LPA1. LPA-stimulated proliferation of SQ-20B cells was attenuated by Ki16425 and Rac1 inhibitor, but not by Y-27632. Infection with doxycycline-regulatable adenovirus vector expressing green fluorescent protein-tagged LPA4 (AdvLPA4G) abolished LPA-stimulated proliferation in SQ-20B cells with the accumulation of G2/M-phasic cells. Ectopic LPA4 induction further downregulated proliferation of Ki16425-treated SQ-20B cells, of which downregulation was partially recovered by LPA. Ectopic LPA4 induction also downregulated proliferation of Rac1 inhibitor-treated SQ-20B cells, however, LPA no longer recovered it. Finally, LPA-induced cell motility was suppressed by ectopic LPA4 expression as well as by Ki16425, Rac1 inhibitor or Y-27632. Our data suggest that LPA4 signaling potentially modulates malignant behavior of SQ-20B cells. LPA signaling, which is mediated by both Edg and non-Edg receptors, may be a determinant of malignant behavior of HNSCC and could therefore be a promising therapeutic target. PMID:23467751

  7. Effects of Low Earth Orbit on Docking Seal Materials

    NASA Technical Reports Server (NTRS)

    Imka, Emily C.; Asmar, Olivia C.; deGroh, Henry C., III; Banks, Bruce A.

    2014-01-01

    Spacecraft docking seals are typically made of silicone elastomers. When such seals are exposed to low Earth orbit (LEO) conditions, they can suffer damage from ultraviolet (UV) radiation and atomic oxygen (AO, or monoatomic oxygen, the predominant oxygen species in LEO). An experiment flew on the International Space Station (ISS) to measure the effects of LEO on seal materials S0383-70 and ELA-SA-401 and various mating counterface materials which included anodized aluminum. Samples flown in different orientations received different amounts of UV and AO. The hypotheses were that most of the damage would be from UV, and 10 days or more of exposure in LEO would badly damage the seals. Eighteen seals were exposed for 543 days in ram (windward), zenith (away from Earth), or wake (leeward) orientations, and 15 control samples (not flown) provided undamaged baseline leakage. To determine post-flight leak rates, each of the 33 seals were placed in an O-ring groove of a leak test fixture and pressure tested over time. Resistance temperature detectors (RTDs), pressure transducers, and LabVIEW (National Instruments) programs were used to measure and analyze the temperature and pressure and calculate leakage. Average leakage of control samples was 2.6 x 10(exp -7) lbs/day. LEO exposure did not considerably damage ELA-SA-401. The S0383-70 flight samples leaked at least 10 times more than ELA-SA-401 in all cases except one, demonstrating that ELA-SA-401 may be a more suitable sealing material in LEO. AO caused greater damage than UV; samples in ram orientation (receiving an AO fluence of 4.3 x 10(exp 21) atoms/(sq cm) and in wake (2.9x 10(exp 20) atoms/(sq cm)) leaked more than those in zenith orientation (1.58 x 10(exp 20) atoms/(sq cm)), whereas variations in UV exposure did not seem to affect the samples. Exposure to LEO did less damage to the seals than hypothesized, and the data did not support the conjecture that UV causes more damage than AO.

  8. The inverse triax x ray diode: An alternate reduced-endpoint-energy bremsstrahlung source

    NASA Astrophysics Data System (ADS)

    Harper-Slaboszewicz, V. J.; Poukey, J. W.; Stygar, W. A.; Fowler, W. E.; Peyton, B.

    1990-02-01

    The inverse triax diode is a high power, low impedance electron diode which offers significant advantages over conventional electron diodes on short-pulse (less than 30 ns FWHM) high power x ray simulators. Parametric calculations show that the radiation efficiency of the inverse triax is competitive with standard diodes for mean photon energies below about 120 keV, and sometimes up to 150 keV. Particle-in-cell code simulations show the impedance behavior and flow pattern in the inverse triax with and without the presence of an anode plasma. The simulation results are used to suggest design rules for inverse triax diodes. Experimental results show good agreement with calculations of the impedance behavior and electron beam dynamics. Using inverse triax diodes, we have produced peak doses of 1.4 x 10(exp 11) rad(TLD)/s over 840 sq cm with a mean photon energy of 120 keV on SPEED and 3.1 x 10(exp 11) rad(TLD)/s over 3700 sq cm with a mean photon energy of 140 keV on Saturn.

  9. Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

    NASA Technical Reports Server (NTRS)

    Garcia, J.; Ramirez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

    2011-01-01

    We investigate the absorption structure of the oxygen in the interstellar medium by analyzing XMM-Newton observations of the low mass X-ray binary Sco X-1. We use simple models based on the O I atomic cross section from different sources to fit the data and evaluate the impact of the atomic data in the interpretation of astrophysical observations. We show that relatively small differences in the atomic calculations can yield spurious results. We also show that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21 - 24.5 Angstrom wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of Epsilon = 10(exp -4) erg/sq cm, and an oxygen column density of N(sub O) approx. = 8-10 x 10(exp 17)/sq cm. Our models are able to reproduce both the K edge and the K(alpha) absorption line from O I, which are the two main features in this region. We find no conclusive evidence for absorption by other than atomic oxygen.

  10. Atomic oxygen beam source for erosion simulation

    NASA Technical Reports Server (NTRS)

    Cuthbertson, J. W.; Langer, W. D.; Motley, R. W.; Vaughn, J. A.

    1991-01-01

    A device for the production of low energy (3 to 10 eV) neutral atomic beams for surface modification studies is described that reproduces the flux of atomic oxygen in low Earth orbit. The beam is produced by the acceleration of plasma ions onto a negatively biased plate of high-Z metal; the ions are neutralized and reflected by the surface, retaining some fraction of their incident kinetic energy, forming a beam of atoms. The plasma is generated by a coaxial RF exciter which produces a magnetically-confined (4 kG) plasma column. At the end of the column, ions fall through the sheath to the plate, whose bias relative to the plasma can be varied to adjust the beam energy. The source provides a neutral flux approximately equal to 5 x 10(exp 16)/sq cm at a distance of 9 cm and a fluence approximately equal to 10(exp 20)/sq cm in five hours. The composition and energy of inert gas beams was diagnosed using a mass spectometer/energy analyzer. The energy spectra of the beams demonstrate energies in the range 5 to 15 eV, and qualitatively show expected dependences upon incident and reflecting atom species and potential drop. Samples of carbon film, carbon-based paint, Kapton, mylar, and teflon exposed to atomic O beams show erosion quite similar to that observed in orbit on the space shuttle.

  11. The Effect of Porosity on the Lift and Drag of Bird's Wings

    NASA Technical Reports Server (NTRS)

    Lichter, Seth

    1974-01-01

    Bird's wings are porous. The mass flux through the wings for various simulated wing loadings was measured and found to average about 2 x 10(exp -4) g/s.sq cm for one feather thickness at the average pigeon wing loading of 45 newtons/sq m. The calculated effect of the flux on lift was found to be less than 1/2 of 1%. Experiments at a typical pigeon flight Reynolds number of 10(exp 5) on flat plates with 3.5% and 14.5% open area spread over the trailing 58% of the chord showed that it is possible to both increase and decrease profile drag, relative to the drag on a non-porous flat plate, by < or = 5%. Stall on the porous plates occurred up to 3 deg earlier than stall on the non-porous plates. From lift calculations and drag measurements it is shown that the effects of porosity on the gliding characteristics of birds are negligible.

  12. Detailed analysis of carrier transport in InAs(0.3)Sb(0.7) layers grown on GaAs substrates by metalorganic chemical-vapor deposition

    NASA Astrophysics Data System (ADS)

    Besikci, C.; Choi, Y. H.; Labeyrie, G.; Bigan, E.; Razeghi, M.; Cohen, J. B.; Carsello, J.; Dravid, V. P.

    1994-11-01

    InAs(0.3)Sb(0.7) layers with mirrorlike morphology have been grown on GaAs substrates by low-pressure metalorganic chemical vapor deposition. A room-temperature electron Hall mobility of 2 x 10(exp 4) sq cm/(V s) has been obtained for a 2-micrometer-thick layer. Low temperature resistivity of the layers depended on TMIn flow rate and layer thickness. Hall mobility decreased monotonically with decreasing temperature below 300 K. A 77 K conductivity profile has shown an anomalous increase in the sample conductivity with decreasing thickness except in the near vicinity of the heterointerface. Experimental and theoretical results suggest that the combined effects of the dislocations generated by the large lattice mismatch and strong surface inversion may lead to deceptive Hall measurements by reflecting typical n-type behavior for a p-type sample, and the measured carried concentration may considerably be affected by the surface conduction up to near room temperature. A quantitative analysis of dislocation scattering has shown significant degradation in electron mobility for dislocation densities above 10(exp 7)/sq cm. The effects of dislocation scattering on hole mobility have been found to be less severe. It has also been observed that there is a critical epilayer thickness (approximately 1 micrometer) below which the surface electron mobility is limited by dislocation scattering.

  13. Observations of the Galactic center 511 keV line

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    1991-01-01

    A review of observations of the positron annihilation 511 keV line from the Galactic center and plane is presented. Emphasis is given to the new data from balloon observations in 1988 and 1989. The positron annihilation source in the direction of the center was found to be turned on again in 1988 October after being observed in a quiescent state since the early 1980s. There is evidence for variability between May and October in 1988. The new observations give the first data in which the line is spectrally resolved and in which the Galactic center and plane components of the annihilation radiation are independently measured. These data support the two-component model of the emission with a variable point source near the center and a steady-state source distributed along the galactic plane. Comparing measurements of narrow and wide field instruments in the 1980s gives a flux of about 8 x 10 exp -4 photons/sq cm/s for the point source in its high state and a flux of about 1.2 x 10 exp-3 photons/sq cm/s/rad for the galactic plane component with a relatively flat distribution over the central radian. The line width for the point source component is about 3 keV FWHM.

  14. Observations of cumulene carbenes, H2CCCC and H2CCC, in TMC-1

    NASA Technical Reports Server (NTRS)

    Kawaguchi, Kentarou; Kaifu, Norio; Ohishi, Masatoshi; Ishikawa, Shin-Ichi; Hirahara, Yasuhiro; Yamamoto, Satoshi; Saito, Shuji; Takano, Shuro; Murakami, Akinori; Vrtilek, J. M.

    1991-01-01

    Attention is given to the carbon chain molecule H2CCCC, detected in the dark cloud TMC-1 for the first time in the course of a molecular line survey using the Nobeyama 45-m telescope. From nine transitions observed in the frequency region of 17-45 GHz, the total column density of H2CCCC in TMC-1 is derived to be 7.5(+/-2.0) x 10 exp 12/sq cm, which is about half of the value reported in IRC + 10216. Five transitions of a related carbon chain molecule, H2CCC, were also detected in TMC-1. The column density of H2CCC obtained in TMC-1, 2.8(+/-0.9) x 10 exp 12/sq cm, is a factor of three smaller than that of H2CCCC. The ortho-to-para abundance ratios of H2CCCC and H2CCC were found to be 4.2 +/-1.5 and 5.9 +/-2.0, respectively. The chemical reactions of these carbon-chain molecules in dark clouds are discussed.

  15. Space-Based Constraints on the Production of Nitric Oxide by Lightning

    NASA Technical Reports Server (NTRS)

    Martin, Randall V.; Sauvage, Bastien; Folkins, Ian; Sioris, Christopher E.; Boone, Christopher; Bernath, Peter; Ziemke, Jerry

    2007-01-01

    .We interpret observations of trace-gases from three satellite platforms to provide top-down constraints on the production of NO by lightning. The space-based observations are tropospheric NO2 columns from SCIAMACHY, tropospheric O3 columns from OMI and MLS, and upper tropospheric HNO3 from ACE-FTS. A global chemical transport model (GEOS-Chem) is used to identify locations and time periods in which lightning would be expected to dominate the trace gas observations. The satellite observations are sampled at those locations and time periods. All three observations exhibit a maximum in the tropical Atlantic region and a minimum in the tropical Pacific. This wave-1 pattern is driven by injection of lightning NO into the upper troposphere over the tropical continents, followed by photochemical production of NO2, HNO3, and O3 during transport. Lightning produces a broad enhancement over the tropical Atlantic and Africa of 2-6 x 10(exp 14) molecules NO2/sq cm, 4 x 10(exp 17) molecules O3/sq cm (15 Dobson Units), and 125 pptv of upper tropospheric HNO3. The lightning background is 25-50% weaker over the tropical Pacific. A global source of 6+/-2 Tg N/yr from lightning in the model best represents the satellite observations of tropospheric NO2, O3, and HNO3.

  16. The Peculiar X-ray Transient IGR 16358-4726

    NASA Technical Reports Server (NTRS)

    Patel, S. K.; Kouveliotou, C.; Tennant, A. F.; Woods, P. M.; King, A.; Ubertini, P.; Winkler, C.; Courvoisier, T.; VanDerKlis, M.; Wachter, S.

    2003-01-01

    The new transient IGR 16358-4726 was discovered on 2003 March 19 with INTEGRAL. We detected the source serendipitously during our 2003 March 24 observation of SGR 1627 - 4lwith the Chandra X-ray observatory at the 1.7 x 10(exp -l0) ergs/s sq cm flux level ( 2-10 keV) with a very high absorption column (N_H = 3.3 x 10(exp 23)/sq cm and a hard power law spectrum of index 0.5(1). We discovered a very strong flux modulation with a period of 5880(50) s and peak-to-peak pulse fraction of 70(6)% (2-10 keV), clearly visible in the X-ray data. The nature of IGR 16358-4726 remains unresolved. The only neutron star systems known with similar spin periods are low luminosity persistent wind-fed pulsars; if this is a spin period, this transient is a new kind of object. If this is an orbital period, then the system could be a compact Low Mass X-ray Binary (LMXB).

  17. Exotic fluoride molecules in IRC +10216: Confirmation of AlF and searches for MgF and CaF

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Apponi, A. J.; Phillips, T. G.

    1994-01-01

    Three new rotational transitions of aluminum fluoride (AlF) at 0.8 and 1.2 mm have been observed. The J = 10-9, J = 8-7, and J = 7-6 lines of AlF at 230, 263, and 329 GHz, respectively, were seen toward IRC +10216 using the Caltech Submillimter Observatory (CSO). Combined with the earlier data obtained for this species at IRAM at 2 and 3 mm, these measurements confirm the presence of the metal halide in this carbon-rich circumstellar shell. Analysis of the CSO and IRAM data suggests that AlF arises from a source with a diameter of theta(sub s) approximately = 5-10 sec and hence is present chiefly in the inner envelope of IRC +10216. In this region, the molecule has a column density of (0.3-1.1) x 10(exp 15)/sq cm, which indicates a fractional abundance of at least approximately 10(exp -9), relative to H2. Searches for the metal fluoride species CaF and MgF have also been conducted toward IRC +10216, but with negative results. The column density upper limits for MgF and CaF are N(sub tot) less than (1-4) x 10(exp 14)/sq cm. Relative abundances of these metal fluoride molecules can be understood in terms of chemical thermodynamic equilibrium. The presence of AlF in IRC +10216 also indicates that large quantities of fluorine must be present in the inner stellar envelope, suggesting that this element may be produced not primarily in explosive nucleosynthesis but rather in helium shell flashes, as indicated also by HF spectroscopy of red giant stars.

  18. On The Nature of the Ultraluminous X-Ray Transient in Cen A (NGC 5128)

    NASA Technical Reports Server (NTRS)

    Ghosh, Kajal K.; Finger, Mark H.; Swartz, Douglas A.; Tennant, Allyn F.; Wu, Kinwah

    2005-01-01

    We combine 20 ROSAT, Chandra, and XMM-Newton observations of the Cen A galaxy to obtain the X-ray light curve of 1RXH J132519.8-430312 (=CXOU J132519.9-430317) spanning 1990 to 2003. The source reached a peak 0.1-2.4 keV flux F(sub X) > 10(exp -12) ergs/sq cm/s during a 10 day span in 1995 July. The inferred peak isotropic luminosity of the source therefore exceeded 3 x 10(exp 39) ergs/s, which places the source in the class of ultra-luminous X-ray sources. Coherent pulsations at 13.264 Hz are detected at the 3 sigma level during a second bright episode (F(sub x) > 3 x 10(exp -13) ergs/sq cm/s) in 1999 December. The source is detected and varies significantly within three additional observations but is below the detection threshold in 7 observations. The X-ray spectrum in 1999 December is best described as a cut-off power law or a disk-blackbody (multi-colored disk). We also detect an optical source, m(sub F555W) approx. 24.1 mag, within the Chandra error circle of 1RXH J132519.8-430312 in Hubble images taken 195 days before the nearest X-ray observation. The optical brightness of this source is consistent with a late O or early B star at the distance of Cen A. The X-ray and optical behavior of 1RXH J132519.8-430312 is therefore similar to the transient Be/X-ray pulsar A 0538-66.

  19. Identifications of Four Integral Sources in the Galactic Plane via CHANDRA Localizations

    NASA Technical Reports Server (NTRS)

    Tomsick, John A.; Chaty, Sylvain; Rodriquez, Jerome; Foschini, Luigi; Walter, Roland; Kaaret, Philip

    2006-01-01

    Hard X-ray imaging of the Galactic plane by the INTEGRAL satellite is uncovering large numbers of 20-100 keV "IGR" sources. We present results from Chandra, INTEGRAL, optical, and IR observations of four IGR sources: three sources in the Norma region of the Galaxy(1GR J16195-4945,IGR J16207-5129, and IGR J16167-4957) and one that is closer to the Galactic center (IGR 5171 95-4100). In all four cases, one relatively bright Chandra source is seen in the INTEGRAL error circle, and these are likely to be the soft X-ray counterparts of the IGR sources. They have hard 0.3-10 keV spectra with power-law photon indices of Gamma = 0.5-1.1. While many previously studied IGR sources show high column densities (NH approx. 10(exp 23)-10(exp 24)/sq cm), only IGR J16195-4945 has a column density that could be as high as 10(exp 23)/sq cm. Using optical and IR sky survey catalogs and our own photometry, we have obtained identifications for all four sources. The J-band magnitudes are in the range 14.9-10.4, and we have used the optical/IR spectral energy distributions (SEDs) to constrain the nature of the sources. Blackbody components with temperature lower limits of >9400 K for IGR J16195-4945 and >18,000 K for IGR J16207-5129 indicate that these are very likely high-mass X-ray binaries (HMXBs). However, for IGR 516167-4957 and IGR J17195-4100, low extinction and the SEDs indicate later spectral types for the putative companions, suggesting that these are not HMXBs.

  20. The 2006-2007 Active Phase of Anomalous X-Ray Pulsar 4U 0142+61: Radiative and Timing Changes, Bursts,and Burst Spectral Features

    NASA Technical Reports Server (NTRS)

    Gavriil, Fotis P.; Dib, Rim; Kaspi, Victoria M.

    2011-01-01

    After at least 6 years of quiescence, Anomalous X-ray Pulsar (AXP) 4U 0142+61 entered an active phase in 2006 March that lasted several months and included six X-ray bursts as well as many changes in the persistent X-ray emission. The bursts, the first seen from this AXP in > 11 years of Rossi X-ray Timing Explorer monitoring, all occurred in the interval between 2006 April 6 and 2007 February 7. The burst durations ranged from 0.4 - 1.8 x 10(exp 3) s. The first five burst spectra are well modeled by blackbodies, with temperatures kT approx 2 - 9 keV. However, the sixth burst had a complicated spectrum that is well characterized by a blackbody plus two emission features whose amplitude varied throughout the burst. The most prominent feature was at 14.0 keV. Upon entry into the active phase the pulsar showed a significant change in pulse morphology and a likely timing glitch. The glitch had a total frequency jump of (1.9+/-0.4) x 10(exp -7) Hz, which recovered with a decay time of 17+/-2 days by more than the initial jump, implying a net spin-down of the pulsar. Within the framework of the magnetar model, the net spin-down of the star could be explained by regions of the superfluid that rotate. slower than the rest. The bursts, flux enhancements, and pulse morphology changes can be explained as arising from crustal deformations due to stresses imposed by the highly twisted internal magnetic field. However, unlike other AXP outbursts, we cannot account for a major twist being implanted in the magnetosphere.

  1. Burst Oscillation Periods from 4U 1636-53: A Constraint on the Binary Doppler Modulation

    NASA Technical Reports Server (NTRS)

    Giles, A. B.; Hill, K. M.; Strohmayer, T. E.; Cummings, N.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    The burst oscillations seen during Type 1 X-ray bursts from low mass X-ray binaries (LMXB) typically evolve in period towards an asymptotic limit that likely reflects the spin of the underlying neutron star. If the underlying period is stable enough, measurement of it at different orbital phases may allow a detection of the Doppler modulation caused by the motion of the neutron star with respect to the center of mass of the binary system. Testing this hypothesis requires enough X-ray bursts and an accurate optical ephemeris to determine the binary phases at which they occurred. We present here a study of the distribution of asymptotic burst oscillation periods for a sample of 26 bursts from 4U 1636-53 observed with the Rossi X-ray Timing Explorer (RXTE). The burst sample includes both archival and proprietary data and spans more than 4.5 years. We also present new optical light curves of V801 Arae, the optical counterpart of 4U 1636-53, obtained during 1998-2001. We use these optical data to refine the binary period measured by Augusteijn et al. to 3.7931206(152) hours. We show that a subset of approx. 70% of the bursts form a tightly clustered distribution of asymptotic periods consistent with a period stability of approx. 1 x 10(exp -4). The tightness of this distribution, made up of bursts spanning more than 4 years in time, suggests that the underlying period is highly stable, with a time to change the period of approx. 3 x 10(exp 4) yr. This is comparable to similar numbers derived for X-ray pulsars. We investigate the period and orbital phase data for our burst sample and show that it is consistent with binary motion of the neutron star with v(sub ns) sin i < 38 and 50 km/s at 90 and 99% confidence, respectively. We use this limit as well as previous radial velocity data to constrain the binary geometry and component masses in 4U 1636-53. Our results suggest that unless the neutron star is significantly more massive than 1.4 solar masses the secondary is

  2. An accurate Galactic N(sub H) map of the north ecliptic pole

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; Lockman, Felix J.; Fassnacht, C.

    1994-01-01

    The Galactic HI column density was measured at 21 min angular resolution over an 8 deg x 9 deg region centered on the north ecliptic pole. Over the region N(sub H) varies smoothly between 3 x 10(exp 20) atoms/sq cm and 8 x 10(exp 20) atoms/sq cm; some structure is seen over most of the map on an 0.5 - 1 deg scale. There are other possible sources of interstellar opacity in this direction which may add an equivalent 10(exp 20)/sq cm of HI. We evaluate the effect of uncertainties in the HI column density on implied X-ray fluxes of extragalactic objects.

  3. Star formation activity in spiral galaxy disks and the properties of radio halos: Observational evidence for a direct dependence

    NASA Technical Reports Server (NTRS)

    Dahlem, Michael; Lisenfeld, Ute; Golla, Gotz

    1995-01-01

    In this article we address observationally the questions: how does star formation (SF) in the disks of galaxies lead to the creation of radio halos, and what minimum energy input into the interstellar medium (ISM) is needed to facilitate this? For the investigation we use a sample of five edge-on galaxies exhibiting radio continuum emmission in their halos and enhanced SF spread over large parts of their disks. In a detailed study of the two galaxies in our sample for which we have the best data, NGC 891 and NGC 4631, we show that the radio halos cut off abruptly at galactocentric radii smaller than those of the underlying thin radio disks. Our most important result is that the halo cutoffs are spatially coincident with the radii where the SF activity in the underlying disks drops sharply. The difference in radius of the emission distributions tracing ongoing SF in the disks (IRAS 50 micrometers, H alpha) versus that of the nonthermal radio continuum thin disks (tracing the distribution of cosmic-ray (CR) electrons) is typically a few kpc. This difference in extent is caused by CR diffusion. We have measured the CR diffusion coefficients in the thin disks of both NGC 891 and NGC 4631. For radial diffusion of CR electrons within the galactic disks the values are D(sub r) = 1.1-2.5 x 10 (exp 29) sq cm/s (NGC 4631) and D(sub r) = 1.2 x 10(exp 29) sq cm/s (NGC 891). For motions in the z-direction in areas within the thin disks where no outflows occur, we derive a firm upper limit of D(sub z) less than or equal to 0.2 x 10(exp 28) sq cm/s for NGC 891. The value for NGC 4631 is D(sub z = 1.4 x 10 (exp 28) sq cm/s. The other three galaxies in our sample, NGC 3044, NGC 4666, and NGC 5775 show (at the sensitivity of our data) less extended, more filamentary radio halos. Isolates spurs or filaments of nonthermal radio continuum emission in their halos are traced only above the most actively star-forming regions in the disks. This, in conjuction with the results obtained for

  4. Irradiation effects on 17-7 PH stainless steel, A-201 carbon steel, and titanium-6-percent-aluminum-4-percent-vanadium alloy

    NASA Technical Reports Server (NTRS)

    Hasse, R. A.; Hartley, C. B.

    1972-01-01

    Irradiation effects on three materials from the NASA Plum Brook Reactor Surveillance Program were determined. An increase of 105 K in the nil-ductility temperature for A-201 steel was observed at a fluence of approximately 3.1 x 10 to the 18th power neutrons/sq cm (neutron energy E sub n greater than 1.0 MeV). Only minor changes in the mechanical properties of 17-7 PH stainless steel were observed up to a fluence of 2 x 10 to the 21st power neutrons/sq cm (E sub n greater than 1.0 MeV). The titanium-6-percent-aluminum-4-percent-vanadium alloy maintained its notch toughness up to a fluence of 1 x 10 to the 21st power neutrons/sq cm (E sub n greater than 1.0 MeV).

  5. Fabrication of highly dense SiN4 ceramics without additives by high pressure sintering

    NASA Technical Reports Server (NTRS)

    Takatori, K.; Shimade, M.; Koizumi, M.

    1984-01-01

    Silicon nitride (Si3N4) is one of candidate materials for the engineering ceramics which is used at high temperatures. The mechanical strengths of hot pressed or sintered Si2N4 ceramics containing some amount of additives, however, are deteriorated at elevated temperatures. To improve the high temperature strength of Si3N4 ceramics, an attempt to consolidate Si3N4 without additives was made by high pressure sintering technique. Scanning electron micrographs of fracture surfaces of the sintered bodies showed the bodies had finely grained and fully self-bonded sintered bodies were 310N sq m at room temperature and 174N/sq m at 1200 C.

  6. SN 1993J: A Type IIb supernova

    NASA Technical Reports Server (NTRS)

    Woosley, S. E.; Eastman, Ronald G. (Editor); Weaver, Thomas A; Pinto, Philip A.

    1994-01-01

    The evolution of the bright Type II supernova discovered last year in M81, SN 1993J, is consistent with that expected for the explosion of a star which on the main sequence had a mass of 13-16 Solar Mass but which, owing to mass exchange with a binary companion (a intially approximately 3-5 AU, depending upon the actual presupernova radius and the masses of the two stars) lost almost all of its hydrogen-rich envelope during late helium burning. At the time of explosion, the helium core mass was 4.0 +/- 0.5 Solar Mass and the hydrogen envelope, 0.20 +/- 0.05 Solar Mass. The envelope was helium and nitrogen-rich (carbon-deficient) and the radius of the star, 4 +/- 1 x 10(exp 13) cm. The luminosity of the presupernova star was 3 + 1 x 10(exp 38) ergs/s, with the companion star contributing an additional approximately 10(exp 38) ergs/s. The star may have been a pulsating variable at the time of the explosion. For an explosion energy near 10(exp 51) ergs (KE at infinity) and an assumed distance of 3.3 Mpc, a mass of Ni-56 in the range 0.07 +/- 0.01 Solar Mass was produced and ejected. This presciption gives a light curve which compares favorably with the bolomatric observations. Color photometry is more restrictive and requires a model in which the hydrogen-envelope mass is low and the mixing of hydrogen inward has been small, but in which appreciable Ni-56 has been mixed outward into the helium and heavy-element core. It is possible to obtain good agreement with B and V light curves during the first 50 days, but later photometry, especially in bands other than B and V, will require a non-local thermo-dynamic equilibrium (LTE) spectral calculation for comparison. Based upon our model, we predict a flux of approximately 10(exp -5)(3.3 Mpc/D)(exp 2) photons/sq cm/s in the 847 keV line of CO-56 at peak during 1993 August. It may be easier to detect the Computonized continuum which peaks at a few times 10(exp -4) photons /s/sq cm/MeV at 40 keV a few months after the

  7. Preliminary Heat-Transfer Measurements on a Hypersonic Glide Configuration Having 79.5 degree Sweepback and 45 degree Dihedral at a Mach Number of 4.95

    NASA Technical Reports Server (NTRS)

    Stainback, Calvin

    1960-01-01

    An experimental investigation was conducted to evaluate the heat-transfer characteristics of a hypersonic glide configuration having 79.5 deg of sweepback (measured in the plane of the leading edges) and 45 of dihedral. The tests were conducted at a nominal Mach number of 4.95 and a stagnation temperature of 400 F. The test-section unit Reynolds number was varied from 1.95 x 10(exp 6) to 12.24 x 10(exp 6) per foot. The results indicated that the laminar-flow heat-transfer rate to the lower surface of the model decreased as the distance from the ridge line increased except for thermocouples located near the semispan at an angle of attack of 00 with respect to the plane of the leading edges. The heat-transfer distribution (local heating rate relative to the ridge-line heating rate) was similar to the theoretical heat-transfer distribution for a two-dimensional blunt body, if the ridge line was assumed to be the stagnation line, and could be predicted by this theory provided a modified Newtonian pressure distribution was used. Except in the vicinity of the apex, the ridge-line heat-transfer rate could also be predicted from two-dimensional blunt-body heat-transfer theory provided it was assumed that the stagnation-line heat-transfer rate varied as the cosine of the effective sweep (sine of the angle of attack of the ridge line). The heat-transfer level on the lower surface and the nondimensional heat-transfer distribution around the body on the lower surface were in qualitative agreement with the results of a geometric study of highly swept delta wings with large positive dihedrals made in reference 1.

  8. A ROSAT Wide Field Camera search for XUV bursts

    NASA Astrophysics Data System (ADS)

    Owens, Alan; Page, Clive G.; Sembay, S.; Schaefer, Bradley E.

    1993-02-01

    We have searched the ROSAT Wide Field Camera all-sky survey for short time-scale (less than 50 s) XUV bursts down to a limiting count of 5 x 10 exp -3 count/sq arcmin, corresponding to an incident flux of about 3 x 10 exp -10 erg/sq cm. In a total observation period of 171 d covering the entire sky, we found no evidence for such events. The present results are used to place limits on the log N-log S relation for gamma-ray bursts and constraints on the spectral shape of the previously reported ultrasoft X-ray transients.

  9. A Remarkable Three Hour Thermonuclear Burst from 4U 1820-30

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Brown, Edward F.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present a detailed observational and theoretical study of an approximately three hour long X-ray burst (the "super burst") observed by the Rossi X-ray Timing Explorer (RXTE) from the low mass X-ray binary (LMXB) 4U 1820-30. This is the longest X-ray burst ever observed from this source, and perhaps one of the longest ever observed in great detail from any source. We show that the super burst is thermonuclear in origin. Its peak luminosity of approximately 3.4 x 10(exp 38) ergs s(exp -1) is consistent with the helium Eddington limit for a neutron star at approximately 7 kpc, as well as the peak luminosity of other, shorter, thermonuclear bursts from the same source. The super burst begins in the decaying tail of a more typical (approximately equal to 20 s duration) thermonuclear burst. These shorter, more frequent bursts are well known helium flashes from this source. The level of the accretion driven flux as well as the observed energy release of upwards of 1.5 x 10(exp 42) ergs indicate that helium could not be the energy source for the super burst. We outline the physics relevant to carbon production and burning on helium accreting neutron stars and present calculations of the thermal evolution and stability of a carbon layer and show that this process is the most likely explanation for the super burst. Ignition at the temperatures in the deep carbon "ocean" requires greater than 30 times the mass of carbon inferred from the observed burst energetics unless the He flash is able to trigger a deflagration from a much smaller mass of carbon. We show, however, that for large columns of accreted carbon fuel, a substantial fraction of the energy released in the carbon burning layer is radiated away as neutrinos, and the heat that is conducted from the burning layer in large part flows inward, only to be released on timescales longer than the observed burst. Thus the energy released during the event possibly exceeds that observed in X-rays by more than a factor of

  10. Spectral studies of SiCl4 + N2O + Ar and SiH4 + Ar mixtures in a shock tube in 160-550 nm range

    NASA Technical Reports Server (NTRS)

    Park, C.; Fujiwara, T.

    1978-01-01

    Gases containing SiO, SiO2, SiH, and Si2 were produced in the reflected-shock region of a shock tube by heating SiCl4 + N2O + Ar and SiH4 + Ar mixtures with shock waves. Spectral absorption characteristics were measured in the 160-550 nm wavelength range and in the 2800-3600 K temperature range and compared to calculated values. The sums of the squares of electronic transition moments at equilibrium separation were derived. It was found that absorption by SiO2 and other known bands of SiO, SiH, and Si2 were too weak to be measured. The cross section of absorption by a continuum, believed due to SiH, varied from 2.5 x 10 to the -17th sq cm at 280 nm to 1.6 x 10 to the -18th sq cm at 440 nm.

  11. A time-dependent gyro-kinetic model of thermal ion upflows in the high-latitude F region

    NASA Technical Reports Server (NTRS)

    Loranc, M.; St.-Maurice, J.-P.

    1994-01-01

    , temperature, and flux exceeded 3 km/s, 2 x 10(exp 4) K, and 10(exp 9)/sq cm/s, respectively, (3) a second transient regime developed wherein the parallel temperature drops to very low values (a few hundred Kelvins), and (4) well after heating ceased, large parallel temperatures and large downward parallel velocities and fluxes developed as the flux tube slowly returned to diffusive equilibrium. The ion velocity distributions during the simulation are often non-Maxwellian and are sometimes composed of two distinct ion populations.

  12. Morphology of the interstellar cooling lines detected by COBE

    NASA Technical Reports Server (NTRS)

    Bennett, C. L.; Fixsen, D. J.; Hinshaw, G.; Mather, J. C.; Moseley, S. H.; Wright, E. L.; Eplee, R. E., Jr.; Gales, J.; Hewagama, T.; Isaacman, R. B.

    1994-01-01

    The Far-Infrared Absolute Spectrophotometer (FIRAS) on the COBE satellite has conducted an unbiased survey of the far-infrared emission from our Galaxy. The first results of this survey were reported by Wright et al. (1991). We report the results of new analyses of this spectral survey, which includes emission lines from 158 micrometer C(+), 122 and 205 micrometer N(+), 370 and 609 micrometer C(0), and CO J = 2 goes to 1 through J = 5 goes to 4. We report the morphological distribution along the Galactic plane (b = 0 deg) of the spectral line emission, and the high Galactic latitude intensities of the C(+) and 205 micrometer N(+) emission. In the Galactic plane the 205 micrometer line of N(+) generally follows the 158 micrometer C(+) line distribution, but the intensities scale as I(N(+) 205 micrometer) varies as I(C(+) 158 micrometer)(exp 1.5) toward the inner Galaxy. The high Galactic latitude intensity of the 158 micrometer fine-structure transition from C(+) is I(C(+) 158 micrometer) = (1.43 +/- 0.12) x 10(exp -6) csc (absolute value of b) ergs/sq cm s sr for absolute value of b greater than 15 deg, and it decreases more rapidly than the far-infrared intensity with increasing Galactic latitude. C(+) and neutral atomic hydrogen emission are closely correlated with a C(+) cooling rate of (2.65 +/- 0.15) x 10(exp -26) ergs/s. We conclude that this emission arises almost entirely from the cold neutral medium. The high Galactic latitude intensity of the 205 micrometer fine-structure transition from N(+) is I(N(+) 205 micrometer) = (4 +/- 1) x 10(exp -8) csc (absolute value of b) ergs/((sq cm)(s)(sr)) arising entirely from the warm ionized medium. We estimate the total ionizing photon rate in the Galaxy to be phi = 3.5 x 10(exp 53) ionizing photons per second, based on the 205 micrometer N(+) transition.

  13. Study of the effects of MeV Ag, Cu, Au, and Sn implantation on the optical properties of LiNbO3

    NASA Technical Reports Server (NTRS)

    Williams, E. K.; Ila, D.; Sarkisov, S.; Curley, M.; Poker, D. B.; Hensley, D. K.; Borel, C.

    1998-01-01

    The authors present the results of characterization of linear absorption and nonlinear refractive index of Au, Ag, Cu and Sn ion implantation into LiNbO3. Ag was implanted at 1.5 MeV to fluences of 2 to 17 x 17(exp 16)/sq cm at room temperature. Au and Cu were implanted to fluences of 5 to 20 x 10(exp 16)/sq cm at an energy of 2.0 MeV. Sn was implanted to a fluence of 1.6 x 10(exp 17)/sq cm at 160 kV. Optical absorption spectrometry indicated an absorption peak for the Au implanted samples after heat treatment at 1,000 C at approx. 620 nm. The Ag implanted samples absorption peaks shifted from approx. 450 nm before heat treatment to 550 nm after 500 C for 1h. Heat treatment at 800 C returned the Ag implanted crystals to a clear state. Cu nanocluster absorption peaks disappears at 500 C. No Sn clusters were observed by optical absorption or XRD. The size of the Ag and Au clusters as a function of heat treatment were determined from the absorption peaks. The Ag clusters did not change appreciably in size with heat treatment. The Au clusters increased from 3 to 9 nm diameter upon heat treatment at 1000 C. TEM analysis performed on a Au implanted crystal indicated the formation of Au nanocrystals with facets normal to the c-axis. Measurements of the nonlinear refractive indices were carried out using the Z-scan method with a tunable dye laser pumped by a frequency doubled mode-locked Nd:YAG laser. The dye laser had a 4.5 ps pulse duration time and 76 MHz pulse repetition rate (575 nm).

  14. The Effect of the Wall Contact and Post-Growth C001-Down on Defects in CdTe Crystals Grown by Contactless PVT

    NASA Technical Reports Server (NTRS)

    Palosz, W.; Grasza, K.; Dudley, M.; Raghothamachar, B.; Cai, L.; Durose, K.; Halliday, D.; Boyall, N. M.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    In crystal growth, the quality of the final material may depend, among other factors, on its interaction with the walls of the ampoule during and after the growth, and on the rate of the crystal cool-down at the end of ate the process. To investigate the above phenomena, a series of CdTe crystal growth processes was carried out, The crystals were grown by physical vapor transport without contact with the side walls of the silica glass ampoules, applying the Low Supersaturation Nucleation technique. The source temperature was 930 C, the undercooling was a few degrees. The crystals, having the diameter of 25 mm, grew at the rate of a few mm per day. The post-growth cool-down to the room temperature was conducted at different rates, and lasted from a few minutes to four days. The crystals were characterized using chemical etching low temperature luminescence, and Synchrotron White Beam X-ray Topography techniques. The dislocation (etch pit) density was measured and its distribution was analyzed by comparison with Poisson curves and with the Normalized Radial Distribution Correlation Function. It was found that the contact of the crystal with silica leads to a strain field and high (in the 105 sq cm range) dislocation (etch pit) density. Similar defect concentrations were found in crystals subjected to fast post-growth cool-down. Typical EPD values for lower cool-down rates and in regions not affected by wall interactions are in the lower 10(exp 4) sq cm range. In some areas the actual dislocation density was about 10(exp 3) sq cm or even less. No apparent effect of the cool-down rate on polygonization was observed. A fine structure could be discerned in low-temperature PL spectra of crystals with low dislocation density.

  15. Protein Crystals Grow Purer in Space: Physics of Phenomena

    NASA Technical Reports Server (NTRS)

    Chernov, Alex A.

    2000-01-01

    This presentation will summarize the quantitative experimental and theoretical results obtained by B.R. Thomas, P.G. Vekilov, D.C. Carter, A.M. Holmes, W.K. Widierow and the Author, the team with expertise in physics, biochemistry, crystallography and engineering. Impurities inhomogeneously trapped by a growing crystal - e.g., producing sectorial structure and/or striations - may induce macroscopic internal stress in it if an impurity molecule has slightly (less than 10%) different shape or volume than the regular one(s) they replace. We tested for the first time plasticity and measured Young modulus E of the triclinic, not cross-linked lysozyme by triple point bending technique. Triclinic lysozyme crystals are purely elastic with E similar or equal to 1/5 (raised dot) 10 (exp 9) partial derivative yn/sq cm. The strength limit, sigma (sub c) similar or equal to 10 (exp -3)E similar or equal to Epsilon (sub c), where sigma (sub c) and epsilon (sub c) are critical stress and strain, respectively. Scaling E and sigma (sub c) with the lattice spacing suggests similar binding stiffness in inorganic and biomolecular crystals. The inhomogeneous internal stress may be resolved in these brittle crystals either by cracking or by creation of misoriented mosaic blocks during, not after growth. If each impurity molecule induces in the lattice elementary strain epsilon (sub 0) similar or equal to 3 (raised dot) 10 (exp -2) (this is maximal elementary strain that can arise at the supersaturation DELTA mu/kT similar or equal to 2 and macroscopic molecular concentration difference between subsequent macrolayers or growth sectors is partial derivativeC similar or equal to 5 (raised dot) 10 (exp -3), the internal strain epsilon similar or equal to epsilon (sub 0) partial derivative C similar or equal to 10 (exp -4). Mosaic misorientation resolving such strain is approximately 30 arcsec. Tenfold increase of impurity concentration may cause cracking. Estimates of stress in an isometric

  16. Photodissociation of Peroxynitric Acid in the Near-IR

    NASA Technical Reports Server (NTRS)

    Roehl, Coleen M.; Nizkorodov, Sergey A.; Zhang, Hui; Blake, Geoffrey A.; Wennberg, Paul O.

    2002-01-01

    Temperature-dependent near-IR photodissociation spectra were obtained for several vibrational overtone transitions of peroxynitric acid (HNO4) with a tunable OPO photolysis/OH laser-induced-fluorescence system. Band-integrated photodissociation cross-sections (definity integral of sigma(sub diss)), determined relative to that for the 3nu(sub 1), OH stretching overtone, were measured for three dissociative bands. Assuming unit quantum efficiency for photodissociation of 3nu(sub 1), we find 2nu(sub 1) + nu(sub 3)(8242/cm) = (1.21 x 10(exp -20) (independent of temperature), 2nu(sub 1) (6900/cm) = 4.09 x 10(exp 18) * e(sup (-826,5/T)) (295 K greater than T greater than 224 K), and nu(sub 1) + 2nu(sub 3) (6252/cm) = 1.87 x 10(exp -19) * e(sup (- 1410.7/T)) (278 K greater than T greater than 240 K) sq cm/molecule cm. The photodissociation cross-sections are independent of pressure over the range 2 to 40 Torr. Temperature-dependent quantum yields (phi) for these transitions were obtained using integrated absorption cross-sections (definity integral of sigma(sub abs)) of HNO4 overtone vibrations measured with a FTIR spectrometer. In the atmosphere, photodissociation in the infrared is dominated by excitation of the first overtone of the OH stretching vibration (2nu((sub 1)). Inclusion of all dissociative HNO4 overtone and combination transitions yields a daytime IR photolysis rate of approximately 1 x 10(esp -1)/s. This process significantly shortens the estimated lifetime of HNO4 in the upper troposphere and lower stratosphere.

  17. Further ROSAT measurements of the period of 4U 1820-30

    NASA Technical Reports Server (NTRS)

    Klis, M. Van Der; Hasinger, G.; Verbunt, F.; Paradijs, J. Van; Belloni, T.; Lewin, W. H. G.

    1993-01-01

    We have made two new observations of 4U 1820-30 with the ROSAT position sensitive proportional counter (PSPC). The measurements do not provide further evidence for a secular period decrease of this source. Instead, after inclusion of our new arrival time measurements the significance of the orbital period derivative drops (from 5.5 to 4.6 sigma), its best-fit value decreases (to P-dot/P =(-5.3 +/- 1.1) x 10(exp -8)/yr) and the formal probability that statistical fluctuations have caused the observed P-dot increases to 0.5% (from 0.003%). We detect light curve changes that are large enough to be the cause of some (or all) of the period changes seen in 4U 1820-30, but not large enough to explain the discrepancy of the observed period derivative with that theoretically predicted. We explore the possibility that the secular period change observed during 1976-1991 could have been dominated by random or systematic changes in the position and shape of an occulting bulge on the disk rim and conclude that phase shifts caused by this mechanism could in principle explain the discrepancy entirely.

  18. Torque Reversal and Spin-Down of the Accretion-Powered Pulsar 4U 1626-67

    NASA Technical Reports Server (NTRS)

    Chakrabarty, Deepto L.; Bildsten, L.; Grunsfeld, J. M.; Koh, D. T.; Prince, T. A.; Vaughan, B. A.; Finger, M. H.; Scott, D. M.; Wilson, R. B.

    1997-01-01

    Over 5 yr of hard X-ray (20-60 keV) monitoring of the 7.66 s accretion-powered pulsar 4U 1626-67 with the Compton Gamma Ray Observatory/BATSE large-area detectors has revealed that the neutron star is now steadily spinning down, in marked contrast to the steady spin-up and spin-down torques differ by only 15% with the neutron star spin changing on a timescale |v/v| approximately equals 5000 yr in both states. The current spin-down rate is itself decreasing on a timescale |v/v| approximately equals 26 yr. The long-term timing history shows small-amplitude variations on a 4000 day timescale, which are probably due to variations in the mass transfer rate. The pulsed 20-60 keV emission from 4U 1626-67 is well-fitted by a power-law spectrum with photon index gamma = 4.9 and a typical pulsed intensity of 1.5 x 10(exp -10) ergs cm (exp -2)s(exp -1). The low count rates with BATSE prohibited us from constraining the reported 42 minute binary orbit, but we can rule out long-period orbits in the range 2 days < or = P(orb) < or = 900 days. We compare the long-term torque behavior of 4U 1626-67 to other disk-fed accreting pulsars and discuss the implications of our results for the various theories of magnetic accretion torques. The abrupt change in the sign of the torque is difficult to reconcile with the extremely smooth spin-down now observed. The strength of the torque noise in 4U 1626-67, approximately 10(exp -22) Hz(exp 2)s(exp -2) Hz(exp -1), is the smallest ever measured for an accreting X-ray pulsar, and it is comparable to the timing noise seen in young radio pulsars. We close by pointing out that the core temperature and external torque (the two parameters potentially relevant to internal sources of timing noise) of an accreting neutron star are also comparable to those of young radio pulsars.

  19. Organic Chemistry of Low-Mass Star-Forming Cores. I. 7 mm Spectroscopy of Chamaeleon MMSl

    NASA Technical Reports Server (NTRS)

    Cordiner, Martn A.; Charnley, Steven B.; Wirtstroem, Eva S.; Smith, Robert G.

    2012-01-01

    Observations are presented of emission lines from organic molecules at frequencies 32-50 GHz in the vicinity of Chamaeleon MMS1. This chemically rich dense cloud core harbors an extremely young, very low luminosity protostellar object and is a candidate first hydrostatic core. Column densities are derived and emission maps are presented for species including polyynes, cyanopolyynes, sulphuretted carbon chains, and methanol. The polyyne emission peak lies about 5000 AU from the protostar, whereas methanol peaks about 15,000 AU away. Averaged over the telescope beam, the molecular hydrogen number density is calculated to be 10(exp 6) / cubic cm and the gas kinetic temperature is in the range 5-7 K. The abundances of long carbon chains are very large and are indicative of a nonequilibrium carbon chemistry; C6H and HC7N column densities are 5.9(sup +2.9) (sub -1.3) x 10(exp 11) /cubic cm and 3.3 (sup +8.0)(sub -1.5) x 10(exp 12)/sq cm, respectively, which are similar to the values found in the most carbon-chain-rich protostars and prestellar cores known, and are unusually large for star-forming gas. Column density upper limits were obtained for the carbon chain anions C4H(-) and C6H(-), with anion-to-neutral ratios [C4H(-)]/[C4H] < 0.02% and [C6H(-l)]/[C6H] < 10%, consistent with previous observations in interstellar clouds and low-mass protostars. Deuterated HC,3 and c-C3H2 were detected. The [DC3N]/[HC,N] ratio of approximately 4% is consistent with the value typically found in cold interstellar gas.

  20. Photochemistry of Saturn's Atmosphere. 1; Hydrocarbon Chemistry and Comparisons with ISO Observations

    NASA Technical Reports Server (NTRS)

    Moses, Julianne I.; Bezard, Bruno; Lellouch, Emmanuel; Gladstone, G. Randall; Feuchtgruber, Helmut; Allen, Mark

    2000-01-01

    To investigate the details of hydrocarbon photochemistry on Saturn, we have developed a one-dimensional diurnally averaged model that couples hydrocarbon and oxygen photochemistry, molecular and eddy diffusion, radiative transfer, and condensation. The model results are compared with observations from the Infrared Space Observatory (ISO) to place tighter constraints on molecular abundances, to better define Saturn's eddy diffusion coefficient profile, and to identify important chemical schemes that control the abundances of the observable hydrocarbons in Saturn's upper atmosphere. From the ISO observations, we determine that the column 12 densities of CH3, CH3C2H, and C4H2 above 10 mbar are 4 (sup +2) (sub -1.5) x 10 (exp 13) cm (sup -2), (1.1 plus or minus 0.3) x 10 (exp 15) cm (exp -2), and (1.2 plus or minus 0.3) x 10 (exp 14) cm (sup -2), respectively. The observed ISO emission features also indicate C2H2 mixing ratios of 1.2 (sup +0.9) (sub -0.6) x 10 (exp -6) at 0.3 mbar and (2.7 plus or minus 0.8) x 10 (exp -7) at 1.4 mbar, and a C2H6 mixing ratio of (9 plus or minus 2.5) x 10 (exp -6) at 0.5 mbar. Upper limits are provided for C2H4, CH2CCH2, C3H8, and C6H2 sensitivity of the model results to variations in the eddy diffusion coefficient profile, the solar flux, the CH4 photolysis branching ratios, the atomic hydrogen influx, and key reaction rates are discussed in detail. We find that C4H2 and CH3C2H are particularly good tracers of important chemical processes and physical conditions in Saturn's upper atmosphere, and C2H6 is a good tracer of the eddy diffusion coefficient in Saturn's lower stratosphere. The eddy diffusion coefficient must be smaller than approximately 3 x 10 (exp 4) sq cm s (sup -1) at pressures greater than 1 mbar in order to reproduce the C2H6 abundance inferred from ISO observations. The eddy diffusion coefficients in the upper stratosphere could be constrained by observations of CH3 radicals if the low-temperature chemistry of CH3 were

  1. Flexural rigidity of the Basin and Range-Colorado Plateau-Rocky Mountain transition from coherence analysis of gravity and topography

    NASA Technical Reports Server (NTRS)

    Lowery, Anthony R.; Smith, Robert B.

    1994-01-01

    Stochastic inversion for flexural loads and flexural rigidity of the continental elastic layer can be accomplished most effectively by using the coherence of gravity and topography. However, the spatial resolution of coherence analysis has been limited by use of two-dimensional periodogram spectra from very large (greater than 10(exp 5)sq km) windows that generally include multiple tectonic features. Using a two-dimensional spectral estimator based on the maximum entropy method, the spatial resolution of flexural proerties can be enhanced by a factor of 4 or more, enabling more detailed analysis at the scale of individual tectonic features. This new approach is used to map the spatial variation of flexural rigidity along the Basin and Range transition to the Colorado Plateau and Middle Rocky Mountains physiographic provinces. Large variations in flexural isostatic responses are found, with rigidities ranging from as low as 8.7 x 10(exp 20) N m (elastic thickness (T(sub e) = 4.6 km) in the Basin and Range to as high as 4.1 x 10(exp 24) N m T(sub e) = 77 km) in the Middle Rocky Mountains. These results compare favorably woith independent determinations of flexural rigidity in the region. Areas of low flexural rigidity correlate strongly with areas of high surface heat flow, as is expected from the contingence of flexural rigidity on a temperature-dependent flow law. Also, late Cenozoic normal faults with large displacements are found primarily in area of low flexural rigidity region. The highest flexural rigidity is found within the Archean Wyoming craton, where evidence suggests that deeply rooted cratonic lithosphere may play a role in determining the distribution of tectonism at the surface.

  2. Observations of 4U 1700-37 with BATSE

    NASA Technical Reports Server (NTRS)

    Rubin, B. C.; Finger, M. H.; Harmon, B. A.; Paciesas, W. S.; Fishman, G. J.; Wilson, R. B.; Wilson, C. A.; Brock, M. N.; Briggs, M. S.; Pendleton, G. N.; Cominsky, L. R.; Roberts, M. S.

    1996-01-01

    The eclipsing binary X-ray source 4U 1700-37 has been continually monitored by the BATSE experiment on the Compton Gamma Ray Observatory since the spring of 1991. Using source measurements at times of Earth occultation, we observe an average (uneclipsed) flux of 0.23 crab in the 20-120 keV band. The flux is highly variable, with occasional flaring behavior on timescales from hundreds of seconds to several hours and intensities as bright as 1 crab. The uneclipsed spectrum is well represented by an optically thin thermal bremsstrahlung model with a temperature of 25 keV independent of source intensity or orbital phase. An upper limit of 4% on the pulse fraction has been obtained for pulse periods between 2 and 700 s. Average orbital light curves from almost 1000 days of occultation measurements have been constructed. These profiles are used to measure: (1) the eclipse semiangle, Theta(sub E) = 28.6 deg +/- 2.1 deg in the 20-120 keV band, and (2) the decrease in orbital period, P(dot)/P = -(3.3 +/- 0.6) x 10(exp -7) 1/ yr. Estimates of system physical parameters are obtained using Monte Carlo simulations to propagate errors in measured and assumed parameters. For the X-ray source mass we find M(sub x) = 2.6(sub -1.4)(sup +2.3) solar mass, and for the mass and radius of the optical companion, M(sub 0) = 30(sub -7)(sup +11) solar mass and R(sub 0) = 18(sub -2)(sup +2) solar radius.

  3. H2SO4 photolysis: A souce of sulfur dioxide in the upper stratosphere

    NASA Technical Reports Server (NTRS)

    Rinsland, C. P.; Gunson, M. R.; Ko, M. K. W.; Weisenstein, D. W.; Zander, R.; Abrams, M. C.; Goldman, A.; Sze, N. D.; Yue, G. K.

    1995-01-01

    Numerous absoption lines of stratospheric sulfer dioxide (SO2) were identified in solar occulation spectra recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer during the Atmospheric Laboratory for Applications and Science (ATLAS)-1 shuttle mission (March 24-April 2, 1992). based on their analysis, a volume mixing ratio profile of SO2 increasing from (13 +/- 4) p.p.t.v. (parts per 10(exp -12) by volume) at 16 mbar (approximately 28 km) to 455 +/- 90 p.p.t.v. at 0.63 mbar (approximately 52 km) was measured with no significant profile differences between 20 deg N and 60 deg S latitude. The increase in the SO2 mixing ratios with altitude indicates the presence of a source of SO2 in the upper stratosphere. Profiles retrieved from ATMOS spectra recorded during shuttle flights in April-May 1985 and April 1993 show similar vertical distributions but lower concentrations. Two-dimensional model calculations with SO2 assumed as the end product of H2SO4 photolysis produce SO2 profiles consistent with the ATMOS measuremnts to within about a factor 2.

  4. Effect of Nb2O5 and V2O5 addition on the superconducting properties of YBa2Cu3O(y) thin films

    SciTech Connect

    Srinivas, S.; Bhatnagar, A.K.; Pinto, R.; Pai, S.P.; Apte, P.R.; Purandare, S.C.; Souza, C.P.D.

    1995-04-01

    The effect of Nb2O5 and V2O5 addition on the superconducting properties and microstructure of YBa2Cu3O(y) has been studied in thin films. Polycrystalline targets for laser ablation were prepared by mixing high purity V2O5 or Nb2O5 powders with a well characterized YBa2Cu3O(y) powder in the range 0 to 4 wt percent by solid state reaction method. Thin films (approximately 1500 A thickness) of the above targets were grown on (100) SrTiO3 (STO) and (100) LaAlO3 (LAO) substrates at 700 C temperature by pulsed laser deposition (PLD) technique. In the case of Nb2O5 addition the authors have noticed an increase in J(sub c) up to 0.5 wt percent and higher additive concentration (greater than 0.5 wt percent) have degraded the superconducting properties. However, in the case of V2O3 addition, there is an improvement in current density and microstructural properties up to 1 wt percent and the superconducting properties degrade for concentrations greater than 1 wt percent. The best J{sub c} for 0.5 wt percent of Nb2O5 added to YBCO thin film is 1.6 x 10(exp 6) A/sq cm and for that of V2O5 added sample is 3.4 x 10(exp 6) A/sq cm at 77 K as compared to the pure YBa2Cu3O(y) (YBCO) film J{sub c} (1.2 x 10(exp 6) A/sq cm) observed on STO substrates. The reason for improvement in J{sub c} and microstructural properties in the case of V2O5 addition could be due to the low melting of V2O5 (690 C) which can act as a very good surfactant during deposition. Over all, the authors have realized that Nb2O5 addition or V2O5 addition to YBCO have shown significant improvement over the undoped YBa2Cu3O(7-x) films grown under identical conditions.

  5. Discovery of a transient MeV range gamma-ray source

    NASA Technical Reports Server (NTRS)

    Briggs, M. S.; Gruber, D. E.; Matteson, J. L.; Peterson, L. E.

    1995-01-01

    The University of California, San Diego (UCSD)/MIT hard X-ray and gamma-ray instrument on the HEAO 1 surveyed the region near the Galactic center 3 times during its lifetime in 1977-1979. During the 1977 September-October scan, a gamma-ray source was detected south of the Galactic center. The source was below the threshold sensitivity in the spring and fall of 1978. The source was detected with the medium energy phoswich scintillation counters which operated over the 80 keV-2 MeV range, had an area of 42 sq cm each, and a 17 deg FWHM aperture. The error box for the source is centered on l = 2.4 deg, b = -12.2 deg, with a 90% confidence error circle of approximately 3.5 deg radius. The flux in the 333-635 keV range was (1.89 +/- 0.29) x 10(exp -5) photons/(sq cm s keV) and was constant within statistics during the 1 month period the source was in the field of view. The spectrum can be characterized as a Gaussian in the range 300 less than or = E less than or = 650 keV, with a FWHM of 249 +/- 51 keV centered on 461 +/- 22 keV. The flux of this broad Gaussian is (6.6 +/- 1.1) x 10(exp -3) photons/(sq cm s). The source is tentatively identified with the 5.57 hr period low-mass X-ray-emitting binary system 1H 1822-371. Assuming this is correct, the ratio of gamma-ray to X-ray luminosity during the outburst was about 5; at a distance of 8 kpc, the gamma ray luminosity is 4 x 10(exp 37) ergs. The emission may be interpreted as a positron-pair plasma ejected from a compact object, possibly a black hole, and annihilating in a thick accretion disk surrounding the object.

  6. Effect of Nb2O5 and V2O5 addition on the superconducting properties of YBa2Cu3O(y) thin films

    NASA Technical Reports Server (NTRS)

    Srinivas, S.; Bhatnagar, A. K.; Pinto, R.; Pai, S. P.; Apte, P. R.; Purandare, S. C.; Souza, C. P. D.

    1995-01-01

    The effect of Nb2O5 and V2O5 addition on the superconducting properties and microstructure of YBa2Cu3O(y) has been studied in thin films. Polycrystalline targets for laser ablation were prepared by mixing high purity V2O5 or Nb2O5 powders with a well characterized YBa2Cu3O(y) powder in the range 0 to 4 wt percent by solid state reaction method. Thin films (approximately 1500 A thickness) of the above targets were grown on (100) SrTiO3 (STO) and (100) LaAlO3 (LAO) substrates at 700 C temperature by pulsed laser deposition (PLD) technique. In the case of Nb2O5 addition we have noticed an increase in J(sub c) up to 0.5 wt percent and higher additive concentration (greater than 0.5 wt percent) have degraded the superconducting properties. However, in the case of V2O3 addition, there is an improvement in current density and microstructural properties up to 1 wt percent and the superconducting properties degrade for concentrations greater than 1 wt percent. The best J(sub c) for 0.5 wt percent of Nb2O5 added YBCO thin film is 1.6 x 10(exp 6) A/sq cm and for that of V2O5 added sample is 3.4 x 10(exp 6) A/sq cm at 77 K as compared to the pure YBa2Cu3O(y) (YBCO) film J(sub c) (1.2 x 10(exp 6) A/sq cm) observed on STO substrates. The reason for improvement in J(sub c) and microstructural properties in the case of V2O5 addition could be due to the low melting of V2O5 (690 C) which can act as a very good surfactant during deposition. Over all, we have realized that Nb2O5 addition or V2O5 addition to YBCO have shown significant improvement over the undoped YBa2Cu3O(7-x) films grown under identical conditions.

  7. Thermal annealing of GaAs concentrator solar cells

    NASA Technical Reports Server (NTRS)

    Curtis, H. B.; Brinker, David J.

    1991-01-01

    Isochronal and isothermal annealing tests were performed on GaAs concentrator cells which were irradiated with electrons of various energies to fluences up to 1 x 10(exp 16) e/sq cm. The results include: (1) For cells irradiated with electrons from 0.7 to 2.3 MeV, recovery decreases with increasing electron energy. (2) As determined by the un-annealed fractions, isothermal and isochronal annealing produce the same recovery. Also, cells irradiated to 3 x 10(exp 15) or 1 x 10(exp 16) e/sq cm recover to similar un-annealed fractions. (3) Some significant annealing is being seen at 150 C although very long times are required.

  8. Survey of electronics capability for SP-100 space reactor power system applications

    NASA Technical Reports Server (NTRS)

    Manvi, Ram; Fujita, Tosh

    1991-01-01

    Because of reports indicating improvements in the radiation tolerance of some electronic parts, a survey was recently performed by SP-100 project personnel to determine the advisability of revising SP-100 SRPS (space reactor power systems) allowable neutron and gamma dose rates in order to reduce the size and mass of the radiation shield and thereby achieve system mass reductions. The survey results indicate that recent developments to increase the radiation tolerance of a limited set of electronics parts do not justify increasing the allowable SP-100 dose rates for electronic components. Specifically, the recent improvements on a limited set of parts do not justify increasing the current SP-100 allowable specifications of 5 x 10 exp 5 rads gamma dose and 1 x 10 exp 13 neutrons/sq cm fluence. However, if the improvements of 108 rads for gammas and 10 exp 15 neutrons/sq cm can be extended to a wide range of parts, significant mass savings would result.

  9. Dissociation of CH4 by electron impact: Production of metastable hydrogen and carbon fragments

    NASA Technical Reports Server (NTRS)

    Finn, T. G.; Carnahan, B. L.; Zipf, E. C.

    1974-01-01

    Metastable fragments produced by electron impact excitation of CH4 have been investigated for incident electron energies from threshold to 300 eV. Only metastable hydrogen and carbon atoms were observed. Onset energies for the production of metastable hydrogen atoms were observed at electron impact energies of 22.0 + or - .5 eV, 25.5 + or - .6 eV, 36.7 + or - .6 eV and 66 + or - 3 eV, and at 26.6 + or - .6 eV for the production of metastable carbon atoms. Most of the fragments appear to have been formed in high-lying Rydberg states. The total metastable hydrogen cross section reaches a maximum value of approximately 1 X 10 to the minus 18th power sq cm at 100 eV. At the same energy, the metastable carbon cross section is 2 x 10 to the minus 19th power sq cm.

  10. RXTE All-Sky Slew Survey. Catalog of X-Ray Sources at B Greater Than 10 deg

    NASA Technical Reports Server (NTRS)

    Revnivtsev, M.; Sazonov, S.; Jahoda, K.; Gilfanov, M.

    2004-01-01

    We report results of a serendipitous hard X-ray (3-20 keV), nearly all-sky (absolute value of b greater than l0 deg.) survey based on RXTE/PCA observations performed during satellite reorientations in 1996-2002. The survey is 80% (90%) complete to a 4(sigma) limiting flux of approx. = 1.8 (2.5) x 10(exp -l1) erg/s sq cm in the 3-20 keV band. The achieved sensitivity in the 3-8 keV and 8-20 keV subbands is similar to and an order of magnitude higher than that of the previously record HEAO-1 A1 and HEAO-1 A4 all-sky surveys, respectively. A combined 7 x 10(exp 3) sq. deg area of the sky is sampled to flux levels below l0(exp -11) erg/ s sq cm (3-20 keV). In total 294 sources are detected and localized to better than 1 deg. 236 (80%) of these can be confidently associated with a known astrophysical object; another 22 likely result from the superposition of 2 or 3 closely located known sources. 35 detected sources remain unidentified, although for 12 of these we report a likely soft X-ray counterpart from the ROSAT all-sky survey bright source catalog. Of the reliably identified sources, 63 have local origin (Milky Way, LMC or SMC), 64 are clusters of galaxies and 100 are active galactic nuclei (AGN). The fact that the unidentified X-ray sources have hard spectra suggests that the majority of them are AGN, including highly obscured ones (N(sub H) greater than l0(exp 23)/sq cm). For the first time we present a log N-log S diagram for extragalactic sources above 4 x l0(exp -12) erg/ s sq cm at 8-20 keV. Key words. cosmo1ogy:observations - diffuse radiation - X-rays general

  11. Properties of large area ErBa2Cu3O(7-x) thin films deposited by ionized cluster beams

    NASA Technical Reports Server (NTRS)

    Levenson, L. L.; Stan, Mark A.; Bhasin, Kul B.

    1991-01-01

    ErBa2Cu3O(7-x) films have been produced by simultaneous deposition of Er, Ba, and Cu from three ionized cluster beam (ICB) sources at acceleration voltages of 0.3 to 0.5 kV. Combining ozone oxidation with ICB deposition at 650 C eliminated any need of post annealing processing. The substrates were rotated at 10 rotations per minute during the deposition which took place at a rate of about 3 to 4 nm. Films with areas up to 70 mm in diameter have been made by ICB deposition. These films, 100 nm thick, were deposited on SrTiO3 (100) substrates at 650 C in a mixture of six percent O3 in O2 at a total pressure of 4 x 10(exp -4) Torr. They had T(sub c) ranging from 84.3 K to 86.8 K over a 70 mm diameter and J(sub c) above 10(exp 6) A/sq cm at 77 K. X ray diffraction measurements of the three samples showed preferential c-axis orientation normal to the substrate surface. Scanning electron micrographs (SEM) of the three samples also show some texture dependence on sample position. For the three samples, there is a correlation between SEM texture, full width at half-maximum of rocking curves and J(sub c) versus temperature curves.

  12. The Goddard High Resolution Spectrograph: Instrument, goals, and science results

    NASA Technical Reports Server (NTRS)

    Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone, D. S.; Linsky, J. L.

    1994-01-01

    The Goddard High Resolution Spectrograph (GHRS), currently in Earth orbit on the Hubble Space Telescope (HST), operates in the wavelength range 1150-3200 A with spectral resolutions (lambda/delta lambda) of approximately 2 x 10(exp 3), 2 x 10(exp 4), and 1 x 10(exp 3). The instrument and its development from inception, its current status, the approach to operations, representative results in the major areas of the scientific goals, and prospects for the future are described.

  13. Vertical Distributions of PH3 in Saturn from Observations of Its 1-0 and 3-2 Rotational Lines

    NASA Technical Reports Server (NTRS)

    Orton, G. S.; Serabyn, E.; Lee, Y. T.

    2000-01-01

    Far-infrared Fourier-transform spectrometer measurements of the 1-0 and 3-2 PH3 transitions in Saturn's disk near 267 and 800 GHz (8.9 and 26.7/cm), respectively, were analyzed simultaneously to derive a global mean profile for the PH3 vertical mixing ratio between 100 and 600 mbar total pressure. The far-infrared spectrum is relatively free from spectral interlopers, suffers minimal absorption or scattering by atmospheric particulates, and contains intrinsically weak PH3 lines that are sensitive to a range of atmospheric depths. The combined spectra are inconsistent with a uniform tropospheric mixing ratio, even with a stratospheric cut-off. They are consistent with a volume mixing ratio of PH3 that drops from 1.2 x 10(exp -5) at 645 mbar pressure to a value of 4.1 x 10(exp -7) at 150 mbar pressure, a decrease that is linear is log abundance vs log pressure. The mixing ratio could drop even more quickly at atmospheric pressures below 150 mbar and still be consistent with the data. The mixing ratio may well remain constant with depth for pressures above 630 mbar. The maximum PH3 mixing ratio in this model is consistent with a [P]/[H] ratio in the deep atmosphere that is about a factor of 10 higher than solar composition. Such a model is consistent with rapid mixing up to the radiative-convective boundary and transport by, for example, vertical waves just above this boundary. In the best fitting model, the eddy diffusion coefficient is approximately 10(exp 4) sq cm near 630 mbar, and it must increase with altitude. The predominant PH3 loss mechanisms are direct photolysis by UV radiation and scavenging by H atoms produced by the photolysis.

  14. Radio Detections During Two State Transitions of the Intermediate-Mass Black Hole HLX-1

    NASA Technical Reports Server (NTRS)

    Webb, Natalie; Cseh, David; Lenc, Emil; Godet, Olivier; Barret, Didier; Corbel, Stephane; Farrell, Sean; Fender, Robert; Gehrels, Neil; Heywood, Ian

    2012-01-01

    Relativistic jets are streams of plasma moving at appreciable fractions of the speed of light. They have been observed from stellar-mass black holes (approx. 3 to 20 solar masses) as well as supermassive black holes (approx.. 10(exp 6) to 10(exp 9) Solar Mass) found in the centers of most galaxies. Jets should also be produced by intermediate-mass black holes (approx. 10(exp 2) to 10(exp 5) Solar Mass), although evidence for this third class of black hole has, until recently, been weak. We report the detection of transient radio emission at the location of the intermediate-mass black hole candidate ESO 243-49 HLX-1, which is consistent with a discrete jet ejection event. These observations also allow us to refine the mass estimate of the black hole to be between approx. 9 × 10(exp 3) Solar Mass and approx. 9 × 10(exp 4) Solar Mass.

  15. An XMM-Newton Observation of 4U1755-33 in Quiescence: Evidence for a Fossil X-Ray Jet

    NASA Technical Reports Server (NTRS)

    Angelini, Lorella; White, Nicholas E.

    2003-01-01

    We report an XMM-Newton observation of the Low mass X-ray Binary (LMXB) and black hole candidate 4U1755-33. This source had been a bright persistent source for at least 25 yrs, but in 1995 entered an extended quiescent phase. 4U1755-33 was not detected with an upper limit to the 2-10 keV luminosity of 5 x 10(exp 31) d(sup 2) (sub 4kpc) ergs per second (where d(sub 4kpc) is the distance in units of 4 kpc) - consistent with the luminosity of other black hole candidates in a quiescent state. An unexpected result is the discovery of a narrow 7 arc min long X-ray jet centered on the position of 4Ul755-33. The spectrum of the jet is similar to that of jets observed from other galactic and extragalactic sources, and may have been ejected from 4Ul755-33 when it was bright. Jets are a feature of accreting black holes, and the detection of a fossil jet provides additional evidence supporting the black hole candidacy of 4U1755-33. The spectral properties of three bright serendipitous sources in the field are reported and it is suggested these are background active galactic nuclei sources.

  16. Meridional Distribution of CH3C2H and C4H2 in Saturn's Stratosphere from CIRS/Cassini Limb and Nadir Observations

    NASA Technical Reports Server (NTRS)

    Guerlet, Sandrine; Fouchet, Thierry; Bezard, Bruno; Moses, Julianne I.; Fletcher, Leigh N.; Simon-Miller, Amy A.; Flasar, F. Michael

    2010-01-01

    Limb and nadir spectra acquired by Cassini/CIRS (Composite InfraRed Spectrometer) are analyzed in order to derive, for the first time, the meridional variations of diacetylene (C4H2) and methylacetylene (CH3C2H) mixing ratios in Saturn's stratosphere, from 5 hPa up to 0.05 hPa and 80 deg S to 45 deg N. We find that the C4H2 and CH3C2H meridional distributions mimic that of acetylene (C2H2), exhibiting small-scale variations that are not present in photochemical model predictions. The most striking feature of the meridional distribution of both molecules is an asymmetry between mid-southern and mid-northern latitudes. The mid-southern latitudes are found depleted in hydrocarbons relative to their northern counterparts. In contrast, photochemical models predict similar abundances at north and south mid-latitudes. We favor a dynamical explanation for this asymmetry, with upwelling in the south and downwelling in the north, the latter coinciding with the region undergoing ring shadowing. The depletion in hydrocarbons at mid-southern latitudes could also result from chemical reactions with oxygen-bearing molecules. Poleward of 60 deg S, at 0.1 and 0.05 hPa, we find that the CH3C2H and C4H2 abundances increase dramatically. This behavior is in sharp contradiction with photochemical model predictions, which exhibit a strong decrease towards the south pole. Several processes could explain our observations, such as subsidence, a large vertical eddy diffusion coefficient at high altitudes, auroral chemistry that enhances CH3C2H and C4H2 production, or shielding from photolysis by aerosols or molecules produced from auroral chemistry. However, problems remain with all these hypotheses, including the lack of similar behavior at lower altitudes. Our derived mean mixing ratios at 0.5 hPa of (2.4 +/- 0.3) 10(exp -10) for C4H2 and of (1.1 +/- 0.3) 10(exp -9) for CH3C2H are compatible with the analysis of global-average ISO observations performed by Moses et al. Finally, we provide

  17. BeppoSAX Observation of NGC 7582: Constraints on the X-Ray Absorber

    NASA Technical Reports Server (NTRS)

    Turner, T. J.; Fiore, F.; Perola, G. C.; Matt, G.; George, I. M.; Piro, L.; Bassani, L.

    1999-01-01

    This paper presents a BeppoSAX observation of NGC 7582 made during 1998 November and an optical spectrum taken in 1998 October. The new X-ray data reveal a previously unknown hard X-ray component in NGC 7582, peaking close to 20 keV. Rapid variability is observed with correlated changes in the 5-10 and 13-60 keV bands indicating that a single continuum component, produced by the active nucleus, provides the, dominant flux across both bands. Comparison between RXTE and BeppoSAX data reveals changes in the 2 - 10 keV flux on timescales of months. Changes in the nuclear X-ray flux appear unrelated to the gradual decline in optical flux noted since the high-state in 1998 July. The 0.5 - 2 keV flux of NGC 7582 is not significantly variable within the BeppoSAX observation, but has brightened by a factor of approximately 2 since the ASCA observation of 1994. While there is some concern about contamination from spatially-unresolved sources, the long-term variability in soft X-ray flux seems most likely associated with the nucleus or an event within the host galaxy of NGC 7582. The 2 - 100 keV spectrum is well fit by a powerlaw of photon index Gamma = 1.95(sup +0.09, sub -0.18) steeper by Delta.Gamma approximately equal 0.40 than the index during the 1994 ASCA observation. The X-ray continuum is attenuated by a thick absorber of N(H) approximately 1.6 x10(exp 24)/sq cm covering approximately 60(sup +10%, sub -14%) of the nucleus plus a screen with N(sub H) approximately 1.4 x 10(exp 23)/ sq cm covering the entire nucleus. Comparison of the BeppoSAX and ASCA spectra shows an increase in the full screen by Delta.N(sub H) approximately equal 7 x 10(exp 22)/sq cm since 1994, confirming the absorption variability found by Xue et al. The increase in soft X-ray flux between 1994 and 1998 is consistent with the appearance of holes in the full screen allowing approximately < 1% of the nuclear flux to escape, and producing some clear lines-of-sight to the broad-line-region. The data

  18. Detection of gamma-ray emission from the quasar PKS 0208-512

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A.

    1993-01-01

    High-energy gamma-ray emission has been detected from the quasar PKS 0208-512 in the energy range above 30 MeV by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory. This region of sky was observed in five different viewing periods, and evidence of time variability in the gamma-ray emission by more than a factor of 3 was found. At the maximum intensity between 1991 September 19 and October 3, the flux density above 100 MeV was (9.1 +/- 0.4) x 10 exp -7 gamma/sq cm per sec. The photon spectrum during this period may be expressed as a power law with an exponent of - 1.69 +/- 0.05 between 30 MeV and 4 GeV. This is the hardest quasar spectrum observed by EGRET up to the present time.

  19. Sea Ice Concentration and Extent

    NASA Technical Reports Server (NTRS)

    Comiso, Josefino C.

    2014-01-01

    Among the most seasonal and most dynamic parameters on the surface of the Earth is sea ice which at any one time covers about 3-6% of the planet. In the Northern Hemisphere, sea ice grows in extent from about 6 x 10(exp 6) sq km to 16 x 10(exp 6) sq km, while in the Southern Hemisphere, it grows from about 3 x 10(exp 6) sq km to about 19 x 10(exp 6) sq km (Comiso, 2010; Gloersen et al., 1992). Sea ice is up to about 2-3 m thick in the Northern Hemisphere and about 1 m thick in the Southern Hemisphere (Wadhams, 2002), and compared to the average ocean depth of about 3 km, it is a relatively thin, fragile sheet that can break due to waves and winds or melt due to upwelling of warm water. Being constantly advected by winds, waves, and currents, sea ice is very dynamic and usually follows the directions of the many gyres in the polar regions. Despite its vast expanse, the sea ice cover was previously left largely unstudied and it was only in recent years that we have understood its true impact and significance as related to the Earths climate, the oceans, and marine life.

  20. Sea Ice

    NASA Technical Reports Server (NTRS)

    Parkinson, Claire L.; Cavalieri, Donald J.

    2005-01-01

    Sea ice covers vast areas of the polar oceans, with ice extent in the Northern Hemisphere ranging from approximately 7 x 10(exp 6) sq km in September to approximately 15 x 10(exp 6) sq km in March and ice extent in the Southern Hemisphere ranging from approximately 3 x 10(exp 6) sq km in February to approximately 18 x 10(exp 6) sq km in September. These ice covers have major impacts on the atmosphere, oceans, and ecosystems of the polar regions, and so as changes occur in them there are potential widespread consequences. Satellite data reveal considerable interannual variability in both polar sea ice covers, and many studies suggest possible connections between the ice and various oscillations within the climate system, such as the Arctic Oscillation, North Atlantic Oscillation, and Antarctic Oscillation, or Southern Annular Mode. Nonetheless, statistically significant long-term trends are also apparent, including overall trends of decreased ice coverage in the Arctic and increased ice coverage in the Antarctic from late 1978 through the end of 2003, with the Antarctic ice increases following marked decreases in the Antarctic ice during the 1970s. For a detailed picture of the seasonally varying ice cover at the start of the 21st century, this chapter includes ice concentration maps for each month of 2001 for both the Arctic and the Antarctic, as well as an overview of what the satellite record has revealed about the two polar ice covers from the 1970s through 2003.

  1. SMM observations of gamma-ray transients. 2: A search for gamma-ray lines between 400 and 600 keV from the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Harris, Michael J.; Share, Gerald H.; Leising, Mark D.

    1994-01-01

    We have search spectra obtained by the Solar Maximum Mission Gamma-Ray Spectrometer during 1981-1988 for evidence of transient gamma-ray lines from the Crab Nebula which have been reported by previous experiments at energies 400-460 keV and 539 keV. We find no evidence for significant emission in any of these lines on time scales between aproximately 1 day and approximately 1 yr. Our 3 sigma upper limits on the transient flux during 1 d intervals are approximately equal to 2.2 x 10(exp -3) photons/sq cm/s for narrow lines at any energy, and approximately equal to 2.9 x 10(exp -3) photons/sq cm/s for the 539 keV line if it is as broad as 42 keV Full Width at Half Maximum (FWHM). We also searched our data during the approximately 5 hr period on 1981 June 6 during which Owens, Myers, & Thompson (1985) reported a strong line at 405 keV. We detected no line down to a 3 upper sigma limit of 3.3 x 10(exp -3) photons/sq cm/s in disagreement with the flux 7.2 +/- 2.1 x 10(exp -3) photos/sq cm/s measured by Owens et al.

  2. Detection of interstellar N2O: A new molecule containing an N-O bond

    NASA Technical Reports Server (NTRS)

    Ziurys, L. M.; Apponi, A. J.; Hollis, J. M.; Snyder, L. E.

    1994-01-01

    A new interstellar molecule, N2O, known as nitrous oxide or 'laughing gas,' has been detected using the NRAO 12 m telescope. The J = 3 - 2, 4 - 3, 5 - 4, and 6 - 5 rotational transitions of this species at 75, 100, 125, and 150 GHz, respectively, were observed toward Sgr B2(M). The column density derived for N2O in this source is N(sub tot) approx. 10(exp 15)/sq. cm, which corresponds to a fractional abundance of approx. 10(exp -9), relative to H2. This value implies abundance ratios of N2O/NO approx. 0.1 and N2O/HNO approx. 3 in the Galactic center. Such ratios are in excellent agreement with predictions of ion-molecule models of interstellar chemistry using early-time calculations and primarily neutral-neutral reactions. N2O is the third interstellar molecule detected thus far containing an N-O bond. Such bonds cannot be so rare as previously thought.

  3. A degree scale anisotropy measurement of the cosmic microwave background near the star Gamma Ursae Minoris

    NASA Technical Reports Server (NTRS)

    Gundersen, J. O.; Clapp, A. C.; Devlin, M.; Holmes, W.; Fischer, M. L.; Meinhold, P. R.; Lange, A. E.; Lubin, P. M.; Richards, P. L.; Smoot, G. F.

    1993-01-01

    Results from a search for anisotropy in the cosmic microwave background (CMB) are presented from the third flight of the Millimeter-wave Anisotropy experiment. The CMB observation occurred over 1.37 hours and covered a 6.24 sq deg area of the sky where very little foreground emission is expected. Significant correlated structure is observed at 6 and 9/cm. At 12/cm we place an upper limit on the structure. The relative amplitudes at 6, 9, and 12/cm are consistent with a CMB spectrum. The spectrum of the structure is inconsistent with thermal emission from known forms of interstellar dust. Synchrotron and free-free emission would both require unusually flat spectral indices at cm wavelengths in order to account for the amplitude of the observed structure. Although known systematic errors are not expected to contribute significantly to any of the three optical channels, excess sidelobe contamination cannot be definitively ruled out. If all the structure is attributed to CMB anisotropy, a value of the weighted rms of the 6 and 9/cm channels of Delta T/T(CMB) = 4.7 +/- 0.8 x 10 exp -5 (+/- 1 sigma) was measured. If the CMB anisotropy is assumed to have a Gaussian autocorrelation function with a coherence angle of 25 arcmin, then the most probable value is Delta T/T(CMB) = 4.2 +1.7 or -1.1 x 10 exp -5, where the +/- refers to the 95 percent confidence limits.

  4. Suzaku Observes Weak Flares from IGRJ17391-3021 Representing a Common Low-Activity State in this SFXT

    NASA Technical Reports Server (NTRS)

    Bodaghee, A.; Tomsick, J. A.; Rodriquez, J.; Chaty, S.; Pottschmidt, K.; Walter, R.; Romano, P.

    2010-01-01

    We present an analysis of a 37-ks observation of the supergiant fast X-ray transient (SFXT) IGRJ17391 -3021 (=XTEJ1739-302) gathered with Suzaku. The source evolved from quiescence to a low-activity level culminating in three weak flares lasting approx.3 ks each in which the peak luminosity is only a factor of 5 times that of the pre-flare luminosity. The minimum observed luminosity was 1.3 x 10(exp 33) erg/s (d/2.7 kpc)(exp 2) in the 0.5-10 keV range. The weak flares are accompanied by significant changes in the spectral parameters including a column density (N(sub H) = (4.1(+0.4/-0.5)) x 10(exp 22)/sq cm) that is approx.2-9 times the absorption measured during quiescence. Accretion of obscuring clumps of stellar wind material can explain both the small flares and the increase in NH. Placing this observation in the context of the recent Swift monitoring campaign, we find that weak-flaring episodes, or at least epochs of enhanced activity just above the quiescent level but well below the moderately bright or high-luminosity outbursts, represent more than 60+/-5% of all observations in the 0.5-10keV energy range making this the most common state in the emission behavior of IGRJ17391 -3021.

  5. Heterogeneous Interactions of ClONO2 and HCl with Sulfuric Acid Tetrahydrate: Implications for the Stratosphere

    NASA Technical Reports Server (NTRS)

    Zhang, Renyi; Jayne, John T.; Molina, Mario J.

    1994-01-01

    The reaction probabilities for ClONO2+H2O- HOCl + HNO3 and ClONO2+ HCl Cl2 +HNO3 have been investigated on sulfuric acid tetrahydrate (SAT, H2SO4-4H2O)surfaces at temperatures between 190 and 230 K and at reactant concentrations that are typical in the lower stratosphere, using a fast-flow reactor coupled to a quadrupole mass spectrometer. The results indicate that the reaction probabilities as well as HCl uptake depend strongly on the thermodynamic state of SAT surface: they decrease significantly with decreasing H2O partial pressure at a given temperature, and decrease with increasing temperature at a given H2O partial pressure, as the SAT changes from the H2O-rich form to the H2SO4-rich form. For H2O-rich SAT at 195 K gamma(sub 1) approx. = -0.01 and gamma(sub 2) greater or equal to 0.1, whereas the values for H2SO4-rich SAT decrease by more than 2 orders of magnitude. At low concentrations of HCl, close to those found in the stratosphere, the amount of HCl taken up by H2O-rich SAT films corresponds to a coverage of the order of a tenth of a monolayer (approx. = 10(exp 14) molecules/sq cm); H2SO4-rich SAT films take up 2 orders of magnitude less HCl (les than 10(exp 12) molecules/sq cm). Substantial HCl uptake at high HCl concentrations is also observed, as a result of surface melting. The data reveal that frozen stratospheric sulfate aerosols may play an important role in chlorine activation in the winter polar stratosphere via processes similar to those occurring on the surfaces of polar stratospheric cloud particles.

  6. A Search for X-Ray Evidence of a Compact Companion to the Unusual Wolf-Rayet Star HD 50896 (EZ CMa)

    NASA Technical Reports Server (NTRS)

    Skinner, Stephen L.; Itoh, Masayuki; Nagase, Fumiaki

    1998-01-01

    We analyze results of a approx.25 ksec ASCA X-ray observation of the unusual Wolf-Rayet star HD 50896 (= EZ CMa). This WN5 star shows optical and ultraviolet variability at a 3.766 day period, which has been interpreted as a possible signature of a compact companion. Our objective was to search for evidence of hard X-rays (greater than or equal to 5 keV) which could be present if the WN5 wind is accreting onto a compact object. The ASCA spectra are dominated by emission below 5 keV and show no significant emission in the harder 5-10 keV range. Weak emission lines are present, and the X-rays arise in an optically thin plasma which spans a range of temperatures from less than or equal to 0.4 keV up to at least approx. 2 keV. Excess X-ray absorption above the interstellar value is present, but the column density is no larger than N(sub H) approx. 10(exp 22)/sq cm. The absorption-corrected X-ray luminosity L(sub x)(0.5 - 10 keV) = 10(exp 32.85) erg/s gives L(sub x)/ L(sub bol) approx. 10(exp -6), a value that is typical of WN stars. No X-ray variability was detected. Our main conclusion is that the X-ray properties of HD 50896 are inconsistent with the behavior expected for wind accretion onto a neutron star or black hole companion. Alternative models based on wind shocks can explain most aspects of the X-ray behavior, and we argue that the hotter plasma near approx. 2 keV could be due to the WR wind shocking onto a normal (nondegenerate) companion.

  7. Optimization of the Orbiting Wide-Angle Light Collectors (OWL) Mission for Charged-Particle and Neutrino Astronomy

    NASA Technical Reports Server (NTRS)

    Krizmanic, John F.; Mitchell, John W.; Streitmatter, Robert E.

    2013-01-01

    OWL [1] uses the Earth's atmosphere as a vast calorimeter to fully enable the emerging field of charged-particle astronomy with high-statistics measurements of ultra-high-energy cosmic rays (UHECR) and a search for sources of UHE neutrinos and photons. Confirmation of the Greisen-Zatsepin-Kuzmin (GZK) suppression above approx. 4 x 10(exp 19) eV suggests that most UHECR originate in astrophysical objects. Higher energy particles must come from sources within about 100 Mpc and are deflected by approx. 1 degree by predicted intergalactic/galactic magnetic fields. The Pierre Auger Array, Telescope Array and the future JEM-EUSO ISS mission will open charged-particle astronomy, but much greater exposure will be required to fully identify and measure the spectra of individual sources. OWL uses two large telescopes with 3 m optical apertures and 45 degree FOV in near-equatorial orbits. Simulations of a five-year OWL mission indicate approx. 10(exp 6) sq km/ sr/ yr of exposure with full aperture at approx. 6 x 10(exp 19) eV. Observations at different altitudes and spacecraft separations optimize sensitivity to UHECRs and neutrinos. OWL's stereo event reconstruction is nearly independent of track inclination and very tolerant of atmospheric conditions. An optional monocular mode gives increased reliability and can increase the instantaneous aperture. OWL can fully reconstruct horizontal and upward-moving showers and so has high sensitivity to UHE neutrinos. New capabilities in inflatable structures optics and silicon photomultipliers can greatly increase photon sensitivity, reducing the energy threshold for n detection or increasing viewed area using a higher orbit. Design trades between the original and optimized OWL missions and the enhanced science capabilities are described.

  8. Fermi-LAT Constraints on the Pulsar Wind Nebula Nature of HESS J1857+026

    NASA Technical Reports Server (NTRS)

    Rousseau, R.; Grondin, M.-H.; VanEtten, A.; Lemoine-Goumard, M.; Bogdanov, S.; Hessels, J. W. T.; Kaspi, V. M.; Arzoumanian, Z.; Camilo, F.; Casandjian, J. M.; Espinoza, C. M.; Johnston, S.; Lyne, A. G.; Smith, D. A.; Stappers, B. W.; Caliandro, G. A.

    2012-01-01

    Since its launch, the Fermi satellite has firmly identified 5 pulsar wind nebulae plus a large number of candidates, all powered by young and energetic pulsars. HESS J1857+026 is a spatially extended gamma-ray source detected by H.E.S.S. and classified as a possible pulsar wind nebula candidate powered by PSR J1856+0245. Aims. We search for -ray pulsations from PSR J1856+0245 and explore the characteristics of its associated pulsar wind nebula. Methods. Using a rotational ephemeris obtained from the Lovell telescope at Jodrell Bank Observatory at 1.5 GHz, we phase.fold 36 months of gamma-ray data acquired by the Large Area Telescope (LAT) aboard Fermi. We also perform a complete gamma-ray spectral and morphological analysis. Results. No pulsation was detected from PSR J1856+0245. However, significant emission is detected at a position coincident with the TeV source HESS J1857+026. The gamma-ray spectrum is well described by a simple power law with a spectral index of Gamma = 1.53 +/- 0.11(sub stat) +/- 0.55(sub syst) and an energy flux of G(0.1 C100 GeV) = (2.71 +/- 0.52(sub stat) +/- 1.51(sub syst) X 10(exp -11) ergs/ sq cm/s. This implies a gamma.ray efficiency of approx 5 %, assuming a distance of 9 kpc, the gamma-ray luminosity of L(sub gamma) (sub PWN) (0.1 C100 GeV) = (2.5 +/- 0.5(sub stat) +/- 1.5(sub syst)) X 10(exp 35)(d/(9kpc))(exp 2) ergs/s and E-dot = 4.6 X 10(exp 36) erg /s, in the range expected for pulsar wind nebulae. Detailed multi-wavelength modeling provides new constraints on its pulsar wind nebula nature.

  9. 1,2-Dichlorohexafluoro-Cyclobutane (1,2-c-C4F6Cl2, R-316c) a Potent Ozone Depleting Substance and Greenhouse Gas: Atmospheric Loss Processes, Lifetimes, and Ozone Depletion and Global Warming Potentials for the (E) and (Z) stereoisomers

    NASA Technical Reports Server (NTRS)

    Papadimitriou, Vassileios C.; McGillen, Max R.; Smith, Shona C.; Jubb, Aaron M.; Portmann, Robert W.; Hall, Bradley D.; Fleming, Eric L.; Jackman, Charles H.; Burkholder, James B.

    2013-01-01

    The atmospheric processing of (E)- and (Z)-1,2-dichlorohexafluorocyclobutane (1,2-c-C4F6Cl2, R-316c) was examined in this work as the ozone depleting (ODP) and global warming (GWP) potentials of this proposed replacement compound are presently unknown. The predominant atmospheric loss processes and infrared absorption spectra of the R-316c isomers were measured to provide a basis to evaluate their atmospheric lifetimes and, thus, ODPs and GWPs. UV absorption spectra were measured between 184.95 to 230 nm at temperatures between 214 and 296 K and a parametrization for use in atmospheric modeling is presented. The Cl atom quantum yield in the 193 nm photolysis of R- 316c was measured to be 1.90 +/- 0.27. Hexafluorocyclobutene (c-C4F6) was determined to be a photolysis co-product with molar yields of 0.7 and 1.0 (+/-10%) for (E)- and (Z)-R-316c, respectively. The 296 K total rate coefficient for the O(1D) + R-316c reaction, i.e., O(1D) loss, was measured to be (1.56 +/- 0.11) × 10(exp -10)cu cm/ molecule/s and the reactive rate coefficient, i.e., R-316c loss, was measured to be (1.36 +/- 0.20) × 10(exp -10)cu cm/molecule/s corresponding to a approx. 88% reactive yield. Rate coefficient upper-limits for the OH and O3 reaction with R-316c were determined to be <2.3 × 10(exp -17) and <2.0 × 10(exp -22)cu cm/molecule/s, respectively, at 296 K. The quoted uncertainty limits are 2(sigma) and include estimated systematic errors. Local and global annually averaged lifetimes for the (E)- and (Z)-R-316c isomers were calculated using a 2-D atmospheric model to be 74.6 +/- 3 and 114.1 +/-10 years, respectively, where the estimated uncertainties are due solely to the uncertainty in the UV absorption spectra. Stratospheric photolysis is the predominant atmospheric loss process for both isomers with the O(1D) reaction making a minor, approx. 2% for the (E) isomer and 7% for the (Z) isomer, contribution to the total atmospheric loss. Ozone depletion potentials for (E)- and (Z

  10. Radiation experiments on Cosmos 2044: K-7-41, parts A, B, C, D, E

    NASA Technical Reports Server (NTRS)

    Frank, A. L.; Benton, E. V.; Benton, E. R.; Dudkin, V. E.; Marenny, A. M.

    1990-01-01

    The Cosmos 2044 biosatellite mission offered the opportunity for radiation measurements under conditions which are seldom available (an inclination of 82.3 deg and attitude of 294 x 216 km). Measurements were made on the outside of the spacecraft under near-zero shielding conditions. Also, this mission was the first in which active temperature recorders (the ATR-4) were flown to record the temperature profiles of detector stacks. Measurements made on this mission provide a comparison and test for modeling of depth doses and LET spectra for orbital parameters previously unavailable. Tissue absorbed doses from 3480 rad (252 rad/d) down to 0.115 rad (8.33 mrad/d) were measured at different depths (0.0146 and 3.20 g/sq cm, respectively) with averaged TLD readings. The LET spectra yielded maximum and minimum values of integral flux of 27.3 x 10(exp -4) and 3.05 x 10(exp -4)/sq cm/s/sr, of dose rate of 7.01 and 1.20 mrad/d, and of dose equivalent rate of 53.8 and 11.6 mrem/d, for LET(sub infinity)-H2O is greater than or equal to 4 keV/micron. Neutron measurements yielded 0.018 mrem/d in the thermal region, 0.25 mrem/d in the resonance region and 3.3 mrem/d in the high energy region. The TLD depth dose and LET spectra were compared with calculations from the modeling codes. The agreement is good but some further refinements are in order. In comparing measurements on Cosmos 2044 with those from previous Cosmos missions (orbital inclinations of 62.8 deg) there is a greater spread (maximum to minimum) in depth doses and an increased contribution from GCRs, and higher LET particles, in the heavy particle fluxes.

  11. Compact radio sources in the starburst galaxy M82 and the Sigma-D relation for supernova remnants

    NASA Technical Reports Server (NTRS)

    Huang, Z. P.; Thuan, T. X.; Chevalier, R. A.; Condon, J. J.; Yin, Q. F.

    1994-01-01

    We have obtained an 8.4 GHz Very Large Array (VLA) A-array map of the starburst galaxy M82 with a resolution Full Width at Half Maximum (FWHM) approximately 0.182 sec. About 50 compact radio sources in the central region of M82 were detected with a peak surface brightness approximately greater than 10(exp -17) W/Hz/sq m/sr. Comparison with previous observations shows that most sources are declining in flux. Three previously visible sources have faded into the background of our map (approximately less than 0.2 mJy/beam), while a few sources, including the second and third brightest radio sources in M82, may have increased slightly in flux over the last decade. No new radio supernova was found. The birth rate of the compact radio sources is estimated to be 0.11 + or - 0.05/yr. We attribute the population of such bright, small supernova remnants (SNRs) in M82 to the high pressure in the central region that can truncate the mass loss during a red supergiant phase or allow dense ionized clouds to be present. The compact radio sources obey a Sigma(radio surface brightness) - D(diameter) relation which is remarkably similar to that followed by supernova remnants in the Galaxy and the Magellanic Clouds and by two of the strongest known extragalactic radio supernovae: SN 1986J and SN 1979C. A least-squares fit to the SNR data gives: Sigma(sub 8.4 GHz) (W/Hz/sq m/sr) = 4.4 x 10(exp -16) D(sub pc)(exp -3.5 +/- 0.1) covering seven orders of magnitude in Sigma. Possible selection effects are discussed and a theoretical discussion of the correlation is presented.

  12. Effect of Hindlimb Unloading on Rat Soleus Fiber Force, Stiffness, and Calcium Sensitivity

    NASA Technical Reports Server (NTRS)

    McDonald Kerry S.; Fitts, Robert H.

    1995-01-01

    The purpose of this study was to examine the time course of change in soleus muscle fiber peak force (N), tension (P(sub 0), kN/sq m), elastic modulus (E(sub 0)), and force-pCa and stiffness - pCa relationships. After 1, 2, or 3 wk of Hindlimb Unloading (HU), single fibers were isolated and placed between a motor arm and a transducer, and fiber diameter, peak absolute force, P(sub 0), E(sub 0), and force-pCa and stiffness-pca relationships were characterized. One week of HU resulted in a significant reduction in fiber diameter (68 +/- 2 vs. 57 +/- 1 micrometer), force (3.59 +/- 0.15 vs. 2.19 +/- 0.12 x 10(exp -4) N), P(sub 0) (102 +/- 4 vs. 85 +/- 2 kN/sq m), and E(sub 0) (1.96 +/- 0.12 vs. 1.37 +/- 0.13 X 10(exp 7) N/sq m) and 2 wk of HU caused a further decline in fiber diameter (45 +/- 1 micrometer), force (1.31 +/- 0.06 x 10(exp -4) N), and E(sub 0)(0.96 +/- 0.09 x 10(exp 7) N/sq m). Although the mean fiber diameter and absolute force continued to decline through 3 wk of HU, P(sub 0) recovered to values not significantly different from control. The P(sub 0)/E(sub 0) ratio was significantly increased after 1 (5.5 +/- 0.3 to 7.1 +/- 0.6), 2, and 3 wk of HU, and the 2-wk (9.5 +/- 0.4) and 3-wk (9.4 +/- 0.8) values were significantly greater than the 1-wk values. The force-pCa and stiffness-pCa curves were shifted right- ward after 1, 2, and 3 wk of HU. At 1 wk of HU, the Ca(2+) sensitivity of isometric force, assessed by Ca(2+) concentration required for half-maximal force, was increased from the control value of 1.83 +/- 0.12 to 2.30 +/- 0.10 micrometers. In conclusion, after HU, the decrease in soleus fiber P(sub 0) can be explained by a reduction in the number of myofibrillar cross bridges per cross-sectional area. Our working hypothesis is that the loss of contractile protein reduces the number of cross bridges per cross-sectional area and increases the filament lattice spacing. The increased spacing reduces cross-bridge force and stiffness, but P(sub 0)/E

  13. Turbulent Aeroheating Testing of Mars Science Laboratory Entry Vehicle in Perfect-Gas Nitrogen

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Collier, Arnold S.

    2007-01-01

    An experimental investigation of turbulent aeroheating on the Mars Science Laboratory entry vehicle heat shield has been conducted in the Arnold Engineering Development Center Hypervelocity Wind Tunnel No. 9. Testing was performed on a 6-in. (0.1524 m) diameter MSL model in pure N2 gas in the tunnel s Mach 8 and Mach 10 nozzles at free stream Reynolds numbers of 4.1x10(exp 6)/ft to 49x10(exp 6)/ft (1.3x10(exp 7)/m to 16x10(exp 7)/m) and 1.2x10(exp 6)/ft to 19x10(exp 6)/ft (0.39x10(exp 7)/m to 62x10(exp 7)/m), respectively. These conditions were sufficient to span the regime of boundary-layer flow from completely laminar to fully-developed turbulent flow over the entire forebody. A supporting aeroheating test was also conducted in the Langley Research Center 20-Inch Mach 6 Air Tunnel at free stream Reynolds number of 1x10(exp 6)/ft to 7x10(exp 6)/ft (0.36x10(exp 7)/m to 2.2x10(exp 7)/m) in order to help corroborate the Tunnel 9 results. A complementary computational fluid dynamics study was conducted in parallel to the wind tunnel testing. Laminar and turbulent predictions were generated for all wind tunnel test conditions and comparisons were performed with the data for the purpose of helping to define uncertainty margins on predictions for aeroheating environments during entry into the Martian atmosphere. Data from both wind tunnel tests and comparisons with the predictions are presented herein. It was concluded from these comparisons that for perfect-gas conditions, the computational tools could predict fully-laminar or fully-turbulent heating conditions to within 10% of the experimental data

  14. Turbulent Aeroheating Testing of Mars Science Laboratory Entry Vehicle

    NASA Technical Reports Server (NTRS)

    Hollis, Brian R.; Collier, Arnold S.

    2008-01-01

    An experimental investigation of turbulent aeroheating on the Mars Science Laboratory entry vehicle heat shield has been conducted in the Arnold Engineering Development Center Hypervelocity Wind Tunnel No. 9. Testing was performed on a 6-in. (0.1524 m) diameter MSL model in pure N2 gas in the tunnel's Mach 8 and Mach 10 nozzles at free stream Reynolds numbers of 4.1 x 10(exp 6)/ft to 49 x 10(exp 6)/ft (1.3 x 10(exp 7)/m to 19 x 10(exp 6/ft) and 1.2 x 10(exp 6)/ft to 19 x 10(exp 6)/ft (0.39 x 10(exp 7)/m to 62 x 10(exp 7)/m), respectively. These conditions were sufficient to span the regime of boundary-layer flow from completely laminar to fully-developed turbulent flow over the entire forebody. A supporting aeroheating test was also conducted in the Langley Research Center 20-Inch Mach 6 Air Tunnel at free stream Reynolds number of 1 x 10(exp 6)/ft to 7 x 10(exp 6)/ft (0.36 x 10(exp 7)/m to 2.2 x 10(exp 7)/m) in order to help corroborate the Tunnel 9 results. A complementary computational fluid dynamics study was conducted in parallel to the wind tunnel testing. Laminar and turbulent predictions were generated for the wind tunnel test conditions and comparisons were performed with the data for the purpose of helping to define uncertainty margins on predictions for aeroheating environments during entry into the Martian atmosphere. Data from both wind tunnel tests and comparisons with the predictions are presented herein. It was concluded from these comparisons that for perfect-gas conditions, the computational tools could predict fully-laminar or fully-turbulent heating conditions to within 12% or better of the experimental data.

  15. Fermi/LAT Observations of Swift/BAT Seyfert Galaxies: On the Contribution of Radio-Quiet Active Galactic Nuclei to the Extragalactic gamma-Ray Background

    NASA Technical Reports Server (NTRS)

    Teng, Stacy H.; Mushotzky, Richard F.; Sambruna, Rita M.; Davis, David S.; Reynolds, Christopher S.

    2011-01-01

    We present the analysis of 2.1 years of Fermi Large Area Telescope (LAT) data on 491 Seyfert galaxies detected by the Swift Burst Alert Telescope (BAT) survey. Only the two nearest objects, NGC 1068 and NGC 4945, which were identified in the Fermi first year catalog, are detected. Using Swift/BAT and radio 20 cm fluxes, we define a new radio-loudness parameter R(sub X,BAT) where radio-loud objects have logR(sub X,BAT) > -4.7. Based on this parameter, only radio-loud sources are detected by Fermi/LAT. An upper limit to the flux of the undetected sources is derived to be approx.2x10(exp -11) photons/sq cm/s, approximately seven times lower than the observed flux of NGC 1068. Assuming a median redshift of 0.031, this implies an upper limit to the gamma-ray (1-100 GeV) luminosity of < approx.3x10(exp 41) erg/s. In addition, we identified 120 new Fermi/LAT sources near the Swift/BAT Seyfert galaxies with significant Fermi/LAT detections. A majority of these objects do not have Swift/BAT counterparts, but their possible optical counterparts include blazars, flat-spectrum radio quasars, and quasars.

  16. Carbon Nanotube-Based Digital Vacuum Electronics and Miniature Instrumentation for Space Exploration

    NASA Technical Reports Server (NTRS)

    Manohara, H.; Toda, R.; Lin, R. H.; Liao, A.; Mojarradi, M.

    2010-01-01

    JPL has developed high performance cold cathodes using arrays of carbon nanotube bundles that produce > 15 A/sq cm at applied fields of 5 to 8 V/micron without any beam focusing. They have exhibited robust operation in poor vacuums of 10(exp -6) to 10(exp -4) Torr- a typically achievable range inside hermetically sealed microcavities. Using these CNT cathodes JPL has developed miniature X-ray tubes capable of delivering sufficient photon flux at acceleration voltages of <20kV to perform definitive mineralogy on planetary surfaces; mass ionizers that offer two orders of magnitude power savings, and S/N ratio better by a factor of five over conventional ionizers. JPL has also developed a new class of programmable logic gates using CNT vacuum electronics potentially for Venus in situ missions and defense applications. These digital vacuum electronic devices are inherently high-temperature tolerant and radiation insensitive. Device design, fabrication and DC switching operation at temperatures up to 700 C are presented in this paper.

  17. Flow of Supercritical Hydrogen in a Uniformly Heated Circular Tube

    NASA Technical Reports Server (NTRS)

    Youn, B.; Mills, A. F.

    1993-01-01

    Turbulent flow of supercritical hydrogen through a uniformly heated circular tube has been investigated using numerical methods, for the range of 4 x 10(exp 5) less than Re less than 3 x 10(exp 6), 5 less than or equal to q(sub W) less than or equal to 10 MW/sq m, 30 less than or equal to T(sub in) less than or equal to 90 K, and 5 less than or equal to P(sub in) less than or equal to 15 MPa. The purpose is to validate a turbulence model and calculation method for the design of active cooling systems of hydrogen-fueled hypersonic aircraft, where the hydrogen fuel a used as coolant. The PHOENICS software package was used for the computations, which required special provision for evaluation of the thermophysical properties of the supercritical hydrogen, and a low Reynolds number form of the k-epsilon turbulence model. Pressure drop and heat transfer data were compared with experiment and existing correlations and good agreement was demonstrated. For the pressure range considered here a "thermal spike" was observed and shown to be due to the secondary peak in specific heat, rather than the primary peak.

  18. Ion-Implanted Diamond Films and Their Tribological Properties

    NASA Technical Reports Server (NTRS)

    Wu, Richard L. C.; Miyoshi, Kazuhisa; Korenyi-Both, Andras L.; Garscadden, Alan; Barnes, Paul N.

    1993-01-01

    This paper reports the physical characterization and tribological evaluation of ion-implanted diamond films. Diamond films were produced by microwave plasma, chemical vapor deposition technique. Diamond films with various grain sizes (0.3 and 3 microns) and roughness (9.1 and 92.1 nm r.m.s. respectively) were implanted with C(+) (m/e = 12) at an ion energy of 160 eV and a fluence of 6.72 x 10(exp 17) ions/sq cm. Unidirectional sliding friction experiments were conducted in ultrahigh vacuum (6.6 x 10(exp -7)Pa), dry nitrogen and humid air (40% RH) environments. The effects of C(+) ion bombardment on fine and coarse-grained diamond films are as follows: the surface morphology of the diamond films did not change; the surface roughness increased (16.3 and 135.3 nm r.m.s.); the diamond structures were damaged and formed a thin layer of amorphous non-diamond carbon; the friction coefficients dramatically decreased in the ultrahigh vacuum (0.1 and 0.4); the friction coefficients decreased slightly in the dry nitrogen and humid air environments.

  19. The Morphology of Passively Evolving Galaxies at Z-2 from HST/WFC3 in the Hubble Ultra Deep Field

    NASA Technical Reports Server (NTRS)

    Cassata, P.; Giavalisco, M.; Guo, Yicheng; Ferguson, H.; Koekemoer, A.; Renzini, A.; Fontana, A.; Salimbeni, S.; Dickinson, M.; Casertano, S.; Conselice, C.J.; Grogin, N.; Lotz, J.M.; Papovich, C.; Lucas, R.A.; Straughn, A.; Gardner, J.P.; Moustakas, L.

    2009-01-01

    We discuss near-IR images of six passive galaxies (SSFR< 10(exp -2)/Gyr) at redshift 1.3 < z < 2.4 with stellar mass M approx 10(exp 11) solar mass, selected from the Great Observatories Origins Deep Survey (GOODS), obtained with WFC3/IR and the Hubble Space Telescope (HST). These WFC3 images provide the deepest and highest angular resolution view of the optical rest-frame morphology of such systems to date. We find that the light profile of these; galaxies is generally regular and well described by a Sersic model with index typical of today's spheroids. We confirm the existence of compact and massive early-type galaxies at z approx. 2: four out of six galaxies have T(sub e) approx. 1 kpc or less. The WFC3 images achieve limiting surface brightness mu approx. 26.5 mag/sq arcsec in the F160W bandpass; yet there is no evidence of a faint halo in the five compact galaxies of our sample, nor is a halo observed in their stacked image. We also find very weak "morphological k-correction" in the galaxies between the rest-frame UV (from the ACS z band), and the rest-frame optical (WFC3 H band): the visual classification, Sersic indices and physical sizes of these galaxies are independent or only mildly dependent on the wavelength, within the errors.

  20. H2 emission as a tracer of molecular hydrogen: Large-scale observations of Orion

    NASA Technical Reports Server (NTRS)

    Luhman, M. L.; Jaffe, D. T.; Keller, L. D.; Pak, Soojong

    1994-01-01

    We have detected extremely extended (greater than 1.5 deg, or 12 pc) near-infrared H2 line emission from the Orion A molecular cloud. We have mapped emission in the 1.601 micrometer(s) upsilon = 6 - 4 Q(1) and 2.121 micrometer(s) upsilon = 1 - 0 S(1) lines of H2 along a approx. 2 deg R.A. cut and from a 6' x 6' region near theta(sup 1) Ori C. The surface brightness of the extended H2 line emission is 10(exp -6) to 10(exp -5) ergs/s/sq. cm/sr. Based on the distribution and relative strengths of the H2 lines, we conclude that UV fluorescene is most likely the dominant H2 emission mechanism in the outer parts of the Orion cloud. Shock-heated gas does not make a major contribution to the H2 emission in this region. The fluorescent component of the total H2 upsilon = 1 - 0 S(1) luminosity from Orion is 30-40 solar luminosity. Molecular hydrogen excited by UV radiation from nearby OB stars contributes 98%-99% of the global H2 line emission from the Orion molecular cloud, even though this cloud has a powerful shock-excited H2 source in its core. The ability to detect large-scale H2 directly opens up new possibilities for the study of molecular clouds.

  1. Supplemental multilayer insulation research facility

    NASA Astrophysics Data System (ADS)

    Dempsey, P. J.; Stochl, R. J.

    1995-07-01

    The Supplemental Multilayer Insulation Research Facility (SMIRF) provides a small scale test bed for conducting cryogenic experiments in a vacuum environment. The facility vacuum system is capable of simulating a Space Shuttle launch pressure profile as well as providing a steady space vacuum environment of 1.3 x 10(exp -4) Newton/sq meter (1 x 10(exp -6) torr). Warm side boundary temperatures can be maintained constant between 111 K (200 R) and 361 K (650 R) using a temperature controlled shroud. The shroud can also simulate a typical lunar day-night temperature profile. The test hardware consists of a cryogenic calorimeter supported by the lid of the vacuum chamber. A 0.45 cu meter (120 gallon) vacuum jacketed storage/supply tank is available for conditioning the cryogen prior to use in the calorimeter. The facility was initially designed to evaluate the thermal performance of insulation systems for long-term storage in space. The facility has recently been used to evaluate the performance of various new insulation systems for LH2 and LN2 ground storage dewars.

  2. Search for Cm-248 in the early solar system

    NASA Technical Reports Server (NTRS)

    Lavielle, B.; Marti, K.; Pellas, P.; Perron, C.

    1992-01-01

    Possible evidence for the presence of Cm-248 in the early solar system was reported from fission gas studies (Rao and Gopalan, 1973) and recently from studies of very high nuclear track densities (not less than 5 x 10 exp 8/sq cm) in the merrillite of the H4 chondrite Forest Vale (F.V.) (Pellas et al., 1987). We report here an analysis of the isotopic abundances of xenon in F.V. phosphates and results of track studies in phosphate/pyroxene contacts. The fission xenon isotopic signature clearly identifies Pu-244 as the extinct progenitor. We calculate an upper limit Cm-248/Pu-244 to be less than 0.0015 at the beginning of Xe retention in F.V. phosphates. This corresponds to an upper limit of the ratio Cm-248/U-235 of not greater than 5 x 10 exp -5 further constraining the evidence for any late addition of freshly synthesized actinide elements just prior to solar system formation. The fission track density observed after annealing the phosphates at 290C (1 hr, which essentially erases spallation recoil tracks) is also in agreement with the Pu-244 abundance inferred from fission Xe. The spallation recoil tracks produced during the 76 Ma cosmic-ray exposure account for the very high track density in merrillites.

  3. Supplemental multilayer insulation research facility

    NASA Technical Reports Server (NTRS)

    Dempsey, P. J.; Stochl, R. J.

    1995-01-01

    The Supplemental Multilayer Insulation Research Facility (SMIRF) provides a small scale test bed for conducting cryogenic experiments in a vacuum environment. The facility vacuum system is capable of simulating a Space Shuttle launch pressure profile as well as providing a steady space vacuum environment of 1.3 x 10(exp -4) Newton/sq meter (1 x 10(exp -6) torr). Warm side boundary temperatures can be maintained constant between 111 K (200 R) and 361 K (650 R) using a temperature controlled shroud. The shroud can also simulate a typical lunar day-night temperature profile. The test hardware consists of a cryogenic calorimeter supported by the lid of the vacuum chamber. A 0.45 cu meter (120 gallon) vacuum jacketed storage/supply tank is available for conditioning the cryogen prior to use in the calorimeter. The facility was initially designed to evaluate the thermal performance of insulation systems for long-term storage in space. The facility has recently been used to evaluate the performance of various new insulation systems for LH2 and LN2 ground storage dewars.

  4. EGRET observations of the BL Lacertae objects 0716+714 and 0521-365

    NASA Technical Reports Server (NTRS)

    Lin, Y. C.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Mayer-Hasselwander, H. A.

    1995-01-01

    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(exp -7) photons/sq cm/s for E greater than 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(exp -7) photons/sq cm/s for E greater than 100 MeV with a 4 sigma significance. The corresponding spectral slope of the photon number distribution is found to be 2.16 +/- 0.36. Details of the observations of these two BL Lac objects with the EGRET telescope are presented.

  5. Gas Scintillation Proportional Counters for High-Energy X-ray Astronomy

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian; Apple, Jeffery

    2003-01-01

    A focal plane array of high-pressure gas scintillation proportional counters (GSPC) for a balloon-borne hard-x-ray telescope is under development at the Marshall Space Flight Center. These detectors have an active area of approx. 20 sq cm, and are filled with a high pressure (10(exp 6) Pa) xenon-helium mixture. Imaging is via crossed-grid position-sensitive phototubes sensitive in the UV region. The performance of the GSPC is well matched to that of the telescopes x-ray optics which have response to 75 keV and a focal spot size of approx. 500 microns. The detector s energy resolution, 4% FWHM at 60 keV, is adequate for resolving the broad spectral lines of astrophysical importance and for accurate continuum measurements. Full details of the instrument and its performance will be provided.

  6. On the possible source of the ionization in the nighttime Martian ionosphere. I - Phobos 2 HARP electron spectrometer measurements

    NASA Technical Reports Server (NTRS)

    Verigin, M. I.; Gringauz, K. I.; Shutte, N. M.; Haider, S. A.; Szego, K.; Kiraly, P.; Nagy, A. F.; Gombosi, T. I.

    1991-01-01

    The measurements of electron spectra in the Martian magnetosphere by the HARP instrument on board the Phobos 2 orbiter are presented. The energy of the electrons (a few tens of electron volts) is sufficient for the impact ionization of the planetary neutral gas, and the characteristic flux of electrons (about 10 exp 8/sq cm per sec) could produce the nightside ionospheric layer with a peak density of a few thousands of electrons per cubic centimeter, which corresponds to densities observed earlier during radio occultations of the Mars 4 and 5 and Viking 1 and 2 spacecraft. The possibility of magnetospheric electron precipitation into the nightside atmosphere of Mars is in agreement with the mainly induced nature of the magnetic field in the planetary magnetotail (as at Venus), while the variability of the Martian nightside ionosphere may be explained by the partial screening of the atmosphere by a weak intrinsic magnetic field of the planet.

  7. Residual strength of cracked 7075 T6 Al-alloy sheets under high loading rates

    NASA Astrophysics Data System (ADS)

    Vasek, A.; Schijve, J.

    1995-04-01

    Dynamic tests were carried out on long sheet specimens with two collinear cracks. First the ligament between the two cracks fails, which implies that the cracks are linked up to a single crack. Linking up did increase the loading rate (dK/dt) of the outer crack tips up to 2 x 10(exp 4) MPa (sq root) m/s. COD measurements during the fast running crack were made. The residual strength was decreased by about 10 percent as compared to the quasi-static result. Fractographic evidence indicates that a high dK/dt has some effect on the shear lips. It promotes some plane-strain influence, associated with an increased yield stress, due to the high plastic strain rate in the crack tip zone. The results were evaluated in terms of fracture mechanics. The results are bearing on the damage tolerance of aircraft structures built up from 7075-T6 sheet material.

  8. Lunar Meteoroid Impact Observations and the Flux of Kilogram-sized Meteoroids

    NASA Technical Reports Server (NTRS)

    Suggs, R. M.; Cooke, W. J.; Koehler, H. M.; Suggs, R. J.; Moser, D. E.; Swift, W. R.

    2011-01-01

    Lunar impact monitoring provides useful information about the flux of meteoroids in the hundreds of grams to kilograms size range. The large collecting area of the night side of the lunar disk, approximately 3.8 10(exp 6)sq km in our camera field-of-view, provides statistically significant counts of the meteoroids striking the lunar surface. Over 200 lunar impacts have been observed by our program in roughly 4 years. Photometric calibration of the flashes observed in the first 3 years along with the luminous efficiency determined using meteor showers and hypervelocity impact tests (Bellot Rubio et al. 2000; Ortiz et al. 2006; Moser et al. 2010; Swift et al. 2010) provide their impact kinetic energies. The asymmetry in the flux on the evening and morning hemispheres of the Moon is compared with sporadic and shower sources to determine their most likely origin. These measurements are consistent with other observations of large meteoroid fluxes.

  9. Egret detection of the blazar PKS 0420-014

    NASA Technical Reports Server (NTRS)

    Radecke, H.-D.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

    1995-01-01

    During its full-sky survey, the Energetic Gamma Ray Experiment Telescope (EGRET) high-energy instrument aboard the Compton Gamma-Ray Observatory detected gamma-ray emission in the energy range above 30 MeV from a source identified as the blazar PKS 0420-014. This object was observed during two separate viewing periods in 1992 February/March and May/June. An intensity decrease above 100 MeV of a factor of at least 1.5 from a maximum of (5.0 +/- 1.4) x 10(exp -7) photons 1 sq cm/s was observed during that time interval indicating extensive variability. The photon spectrum in the range between 30 and 10,000 MeV at the time of the maximum intensity is well represented by a power law with an exponent of -1.9 +/- 0.3. Some similarities with other EGRET detected blazars are briefly discussed.

  10. Detection of high-energy gamma rays from quasar PKS 0528 + 134 by EGRET on the Compton Gamma Ray Observatory

    NASA Technical Reports Server (NTRS)

    Hunter, S. D.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1993-01-01

    The first several pointing directions of the Compton Gamma Ray Observatory, launched on 1991 April 5, were toward the Galactic anticenter. In addition to the known gamma-ray sources, Crab and Geminga, high-energy gamma-ray emission was observed from the quasar PKS 0528 + 134 by the Energetic Gamma Ray Experiment Telescope (EGRET). A redshift measurement, reported here, of 2.07 confirms the identification of this object as a quasar. The differential photon spectrum is well represented by a power law with an exponent of 2.56 +/- 0.09 and a photon intensity above 100 MeV of (8.4 +/- 1.0) x 10 exp -7 photons sq cm/s. There is evidence for time variability on a time scale of a few days.

  11. OSSE observations of the Crab pulsar

    NASA Technical Reports Server (NTRS)

    Ulmer, M. P.; Matz, S. M.; Cameron, R. A.; Grabelsky, D. A.; Grove, J. E.; Johnson, W. N.; Jung, G. V.; Kinzer, R. L.; Kurfess, J. D.; Leising, M. D.

    1992-01-01

    Preliminary results are presented of the Compton Gamma Ray Observatory Oriented Scintillation Spectrometer Experiment (OSSE) observations of the Crab pulsar. The pulsar energy spectra and light curves are in general agreement with previous observations, validating the OSSE pulsar data acquisition modes and data analysis algorithms. The data suggest that the spectrum of the pulsar varies throughout the light curve. The 'interpulse' region has a slightly flatter spectrum in the approx. 60 to 250 keV region and a slightly steeper spectrum at higher energies than the two main pulses. No evidence was found for any lines in the spectra with a typical sensitivity of about 10(exp -4) photons/sq cm/s.

  12. Stochastic Acceleration of Ions Driven by Pc1 Wave Packets

    NASA Technical Reports Server (NTRS)

    Khazanov, G. V.; Sibeck, D. G.; Tel'nikhin, A. A.; Kronberg, T. K.

    2015-01-01

    The stochastic motion of protons and He(sup +) ions driven by Pc1 wave packets is studied in the context of resonant particle heating. Resonant ion cyclotron heating typically occurs when wave powers exceed 10(exp -4) nT sq/Hz. Gyroresonance breaks the first adiabatic invariant and energizes keV ions. Cherenkov resonances with the electrostatic component of wave packets can also accelerate ions. The main effect of this interaction is to accelerate thermal protons to the local Alfven speed. The dependencies of observable quantities on the wave power and plasma parameters are determined, and estimates for the heating extent and rate of particle heating in these wave-particle interactions are shown to be in reasonable agreement with known empirical data.

  13. Prompt ionization in the CRIT II barium releases

    NASA Astrophysics Data System (ADS)

    Torbert, R. B.; Kletzing, C. A.; Liou, K.; Rau, D.

    1992-05-01

    Observations of electron and ion distributions inside a fast neutral barium jet in the ionosphere show significant fluxes within 4 km of release, presumably related to beam plasma instability processes involved in the Critical Ionization Velocity (CIV) effect. Electron fluxes exceeding 5 x 10 exp 12/sq cm-str-sec-keV were responsible for ionizing both the streaming barium and ambient oxygen. Resulting ion fluxes seem to be consistent with 1-2 percent ionization of the fast barium, as reported by optical observations, although the extended spatial distribution of the optically observed ions is difficult to reconcile with the in situ observations. When the perpendicular velocity of the neutrals falls below critical values, these processes shut off. Although these observations resemble the earlier Porcupine experimental results (Haerendel, 1982), theoretical understanding of the differences between these data and that of earlier negative experiments is still lacking.

  14. Prompt ionization in the CRIT II barium releases. [Critical Ionization Tests

    NASA Technical Reports Server (NTRS)

    Torbert, R. B.; Kletzing, C. A.; Liou, K.; Rau, D.

    1992-01-01

    Observations of electron and ion distributions inside a fast neutral barium jet in the ionosphere show significant fluxes within 4 km of release, presumably related to beam plasma instability processes involved in the Critical Ionization Velocity (CIV) effect. Electron fluxes exceeding 5 x 10 exp 12/sq cm-str-sec-keV were responsible for ionizing both the streaming barium and ambient oxygen. Resulting ion fluxes seem to be consistent with 1-2 percent ionization of the fast barium, as reported by optical observations, although the extended spatial distribution of the optically observed ions is difficult to reconcile with the in situ observations. When the perpendicular velocity of the neutrals falls below critical values, these processes shut off. Although these observations resemble the earlier Porcupine experimental results (Haerendel, 1982), theoretical understanding of the differences between these data and that of earlier negative experiments is still lacking.

  15. Identification of the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch in stratospheric solar occultation spectra

    NASA Technical Reports Server (NTRS)

    Perrin, A.; Flaud, J.-M.; Camy-Peyret, C.; Goldman, A.; Rinsland, C. P.; Gunson, M. R.

    1994-01-01

    The spectroscopic identification for the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch at 830.4/cm is reported based on 0.01/cm resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025/cm resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(exp -18)/cm/mol/sq cm at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated.

  16. Unusual features in the persistent emission of the Rapid Burster

    NASA Technical Reports Server (NTRS)

    Lubin, Lori M.; Lewin, Walter H. G.; Van Paradijs, Jan; Van Der Klis, Michiel

    1993-01-01

    Several distinct features in the persistent X-ray emission after long (greater than 30 s) type II bursts from the Rapid Burster were discovered in August 1985. A specific pattern characterized by a 'hump' was observed in the early portion of the persistent emission after type II bursts with integrated fluxes less than about 4.8 x 10 exp -6 erg/sq cm. This hump which typically lasts about 200 s is almost never observed after bursts with fluences greater than this value. The emission during the hump is found to be always harder than the average persistent emission. Quasi-periodic oscillations with frequencies of about 40 mHz observed in 10 cases occur exclusively during a hump. The persistent emission also exhibited sharp 'glitches' and small 'bumps' lasting about 20-100 s. The glitches always occurred at the same phase in the intervals between bursts. In seven cases the glitches were followed by a bump.

  17. Physical processes in the plasma mantle of Venus

    NASA Technical Reports Server (NTRS)

    Szego, K.; Shapiro, V. S.; Shevchenko, V. I.; Sagdeev, R. Z.; Kasprzak, W. T.; Nagy, A. F.

    1991-01-01

    The results are presented of a study, which analyzed data from 10 Pioneer Venus orbits in order to see whether similar wave particle interaction processes also exist in the corresponding region around Venus. The first conclusion is that the apparent physical processes in the mantle are indeed similar around Venus and Mars. The planetary thermal O(+) ions outside the ionopause interact with the shocked solar wind and excite electrostatic waves close to the lower hybrid frequency. These waves propagate inwards, heating first the electron and deeper down in the ionosphere the thermal ion population. The observed superthermal ions are believed to be the product of this wave particle interaction process. It is also concluded that the wave energy transferred to the thermal electrons is of the right magnitude (about 4 x 10 exp 9 eV/sq cm s) to provide the supplemental heat source necessary to reconcile observed and calculated electron temperatures in the ionosphere.

  18. An observation of the Galactic center hard X-ray source, 1E 1740.7-2942, with the Caltech coded-aperture telescope

    NASA Technical Reports Server (NTRS)

    Heindl, William A.; Cook, Walter R.; Grunsfeld, John M.; Palmer, David M.; Prince, Thomas A.; Schindler, Stephen M.; Stone, Edward C.

    1993-01-01

    The Galactic center region hard X-ray source IE 1740.7-2942 has been observed with the Caltech Gamma-Ray Imaging Payload (GRIP) from Alice Springs, Australia, on 1988 April 12 and on 1989 April 3 and 4. We report here results from the 1989 measurements based on 14 hr of observation of the Galactic center region. The observations showed IE 1740.7-2942 to be in its normal state, having a spectrum between 35 and 200 keV characterized by a power law with an exponent of -2.2 +/- 0.3 and flux at 100 keV of (7.0 +/- 0.7) x 10 exp -5 sq cm s keV. No flux was detected above 200 keV. A search for time variability in the spectrum of IE 1740.7-2942 on one hour time scales showed no evidence for variability.

  19. Swift, INTEGRAL, RXTE, and Spitzer Reveal IGR J16283-4838

    NASA Technical Reports Server (NTRS)

    Beckmann, V.; Gehrels, N.; Markwardt, C.; Barthelmy S.; Soldi, S.; Paizis, A.; Mowlavi, N.; Kennca, J. A.; Burrows, D. N.; Chester, M.

    2005-01-01

    We present the first combined study of the recently discovered source IGR J16283-4838 with Swift, INTEGRAL, and RXTE. The source, discovered by INTEGRAL on April 7, 2005, shows a highly absorbed (variable N(sub H) = 0.4-1.7 x 10(exp 23) /sq cm) and flat (Gamma approx. 1) spectrum in the Swift/XRT and RXTE/PCA data. No optical counterpart is detectable (V > 20 mag), but a possible infrared counterpart within the Swift/XRT error radius is detected in the 2MASS and Spitzer/GLIMPSE survey. The observations suggest that IGR J16283-4838 is a high mass X-ray binary containing a neutron star embedded in Compton thick material. This makes IGR J16283-4838 a member of the class of highly absorbed HMXBs, discovered by INTEGRAL.

  20. Effect of particle size and particle size distribution on physical characteristics, morphology and crystal structure of explosively compacted high-T(sub c) superconductors

    NASA Technical Reports Server (NTRS)

    Kotsis, I.; Enisz, M.; Oravetz, D.; Szalay, A.

    1995-01-01

    A superconductor, of composition Y(Ba,K,Na)2Cu3O(x)/F(y) and a composite of composition Y(Ba,K,Na)2Cu3O(x)/F(y) + Ag, with changing K, Na and F content but a constant silver content (Ag = 10 mass%) was prepared using a single heat treatment. the resulting material was ground in a corundum lined mill, separated to particle size fractions of 0-40 micron, 0-63 micron and 63-900 micron and explosively compacted, using an explosive pressure of 10(exp 4) MPa and a subsequent heat treatment. Best results were obtained with the 63-900 micron fraction of composition Y(Ba(1.95) K(0.01)Cu3O(x)F(0),(05)/Ag: porosity less than 0.01 cu cm/g and current density 2800 A/sq cm at 77K.

  1. Performance of Soviet and US hydrogen masers

    NASA Technical Reports Server (NTRS)

    Uljanov, Adolph A.; Demidov, Nikolai A.; Mattison, Edward M.; Vessot, Robert F. C.; Allan, David W.; Winkler, Gernot M. R.

    1990-01-01

    The frequencies of Soviet- and U.S.-built hydrogen masers located at the Smithsonian Astrophysical Observatory and at the United States Naval Observatory (USNO) were compared with each other and, via Global Positioning System (GPS) common-view measurements, with three primary frequency-reference scales. The best masers were found to have fractional frequency stabilities as low as 6 times 10(exp -16) for averaging times of approximately 10(exp 4) s. Members of the USNO maser ensemble provided frequency prediction better than 1 times 10(exp 14) for periods up to a few weeks. The frequency residuals of these masers, after removal of frequency drift and rate of change of drift, had stabilities of a few parts in 10(exp -15), with serveral masers achieving residual stabilities well below 1 times 10(exp -15) for intervals from 10(exp 5)s to 2 times 10(exp 6)s. The fractional frequency drifts of the 13 masers studied, relative to the primary reference standards, ranged from -0.2 times 10(exp -15)/day to +9.6 times 10(exp -15)/day.

  2. A study of the superconducting properties of YBa2Cu(9-x)Nb(x)O(y) thin films

    NASA Technical Reports Server (NTRS)

    Srinivas, S.; Bhatnagar, A. K.; Pinto, R.; Pai, S. P.; Apte, P. R.; Purandare, S. C.; Dsousa, C. P.

    1995-01-01

    Effect of Niobium substitution at the copper site in YBa2Cu3O(7-x) was studied in thin film form. The films were deposited by laser ablation technique using the targets of the YBa2Cu(3-x)Nb(x)O(y) where x = 0.0, 0.025, 0.05, 0.1, 0.2, 0.4, 0.8 and 1.0 under identical deposition conditions on SrTiO3 (100) substrates. Films were characterized by XRD, resistivity, I-V and J(sub c) measurements. Films made from x = 0.025 and 0.05 concentrations of Nb substituted targets showed relatively improved superconducting properties compared to that of undoped films. the best J(sub c) realized for x - 0.025 Nb concentration was 1.8 x 10(exp 6) A/sq cm and for 0.05 Nb concentration it was 3.2 x 10(exp 6) A/sq cm at 77 K. However, degradation of the superconducting properties, with the increase of x is greater than or equal to 0.1 Nb concentration and drastic suppression and complete loss of superconductivity was noticed for x is greater than or equal to 0.4. The growth of impurity phase YBa2NbO6 for x = 0.1 and above of Nb concentration was noted from XRD (X-Ray Diffraction) patterns. However, the site occupancy of Nb could not be confirmed from these studies.

  3. A study of the superconducting properties of YBa2Cu(9-x)Nb(x)O(y) thin films

    NASA Astrophysics Data System (ADS)

    Srinivas, S.; Bhatnagar, A. K.; Pinto, R.; Pai, S. P.; Apte, P. R.; Purandare, S. C.; Dsousa, C. P.

    1995-04-01

    Effect of Niobium substitution at the copper site in YBa2Cu3O(7-x) was studied in thin film form. The films were deposited by laser ablation technique using the targets of the YBa2Cu(3-x)Nb(x)O(y) where x = 0.0, 0.025, 0.05, 0.1, 0.2, 0.4, 0.8 and 1.0 under identical deposition conditions on SrTiO3 (100) substrates. Films were characterized by XRD, resistivity, I-V and J(sub c) measurements. Films made from x = 0.025 and 0.05 concentrations of Nb substituted targets showed relatively improved superconducting properties compared to that of undoped films. the best J(sub c) realized for x - 0.025 Nb concentration was 1.8 x 10(exp 6) A/sq cm and for 0.05 Nb concentration it was 3.2 x 10(exp 6) A/sq cm at 77 K. However, degradation of the superconducting properties, with the increase of x is greater than or equal to 0.1 Nb concentration and drastic suppression and complete loss of superconductivity was noticed for x is greater than or equal to 0.4. The growth of impurity phase YBa2NbO6 for x = 0.1 and above of Nb concentration was noted from XRD (X-Ray Diffraction) patterns. However, the site occupancy of Nb could not be confirmed from these studies.

  4. Fourier transform-infrared studies of thin H2SO4/H2O films: Formation, water uptake, and solid-liquid phase changes

    NASA Technical Reports Server (NTRS)

    Middlebrook, Ann M.; Iraci, Laura T.; Mcneill, Laurie S.; Koehler, Birgit G.; Wilson, Margaret A.; Saastad, Ole W.; Tolbert, Margaret A.; Hanson, David R.

    1993-01-01

    Fourier transform-infrared (FTIR) spectroscopy was used to examine films representative of stratospheric sulfuric acid aerosols. Thin films of sulfuric acid were formed in situ by the condensed phase reaction of SO3 with H2O. FTIR spectra show that the sulfuric acid films absorb water while cooling in the presence of water vapor. Using stratospheric water pressures, the most dilute solutions observed were greater than 40 wt % before simultaneous ice formation and sulfuric acid freezing occurred. FTIR spectra also revealed that the sulfuric acid films crystallized mainly as sulfuric acid tetrahydrate (SAT). Crystallization occurred either when the composition was about 60 wt% H2SO4 or after ice formed on the films at temperatures 1-4 K below the ice frost point. Finally, we determined that the melting point for SAT depended on the background water pressure and was 216-219 K in the presence of 4 x 10(exp -4) Torr H2O. Our results suggest that once frozen, sulfuric acid aerosols in the stratosphere are likely to melt at these temperatures, 30 K colder than previously thought.

  5. Optical interferometer in space

    NASA Technical Reports Server (NTRS)

    Bender, Peter L.; Faller, J. E.; Hall, J. L.; Hils, D.; Stebbins, R. T.; Vincent, Mark A.

    1989-01-01

    The present design concepts for a Laser Gravitational Wave Observatory in Space are described. Laser heterodyne distance measurements are made between test masses located in three spacecraft separated by roughly 10(exp 6) km. The major technology issues are: the reduction of spurious acceleration noise for the test masses to below 2 x 10(exp -15) cm/sq sec/Hz(0.5) from 10(exp -5) to 10(exp -3) Hz; and the measurement of changes in the difference of the antenna arm lengths to 5 x 10(exp -11) cm/Hz(0.5) from 10(exp -3) to 1 Hz with high reliability. The science objectives are: to measure discrete sinusoidal gravitational wave signals from individual sources with periods of 1 second to 1 day; to measure the stochastic background due to unresolved binaries; and to search for gravitational wave pulses with periods longer than 1 sec from possible exotic sources such as gravitational collapse of very massive objects.

  6. The SWIFT Gamma-Ray Burst X-Ray Telescope

    NASA Technical Reports Server (NTRS)

    Hill, J. E.; Burrows, D. N.; Nousek, J. A.; Wells, A.; Chincarini, G.; Abbey, A. F.; Angelini, L.; Beardmore, A.; Brauninger, H. W.; Chang, W.

    2006-01-01

    The Swift Gamma-Ray Burst Explorer is designed to make prompt multi-wavelength observations of Gamma-Ray Bursts and GRB afterglows. The X-ray Telescope enables Swift to determine GRB positions with a few arcseconds accuracy within 100 seconds of the burst onset. The XRT utilizes a mirror set built for JET-X and an XMM-Newton/ EPIC MOS CCD detector to provide a sensitive broad-band (0.2-10 keV) X-ray imager with an effective area of more than 120 sq cm at 1.5 keV, a field of view of 23.6 x 23.6 arcminutes, and an angular resolution of 18 arcseconds (HPD). The detection sensitivity is 2x10(exp 14) erg/sq cm/s in 10(exp 4) seconds. The instrument provides automated source detection and position reporting within 5 seconds of target acquisition. It can also measure the redshifts of GRBs with Iron line emission or other spectral features. The XRT operates in an auto-exposure mode, adjusting the CCD readout mode automatically to optimize the science return as the source intensity fades. The XRT measures spectra and lightcurves of the GRB afterglow beginning about a minute after the burst and follows each burst for days or weeks. We provide an overview of the X-ray Telescope scientific background from which the systems engineering requirements were derived, with specific emphasis on the design and qualification aspects from conception through to launch. We describe the impact on cleanliness and vacuum requirements for the instrument low energy response and to maintain the high sensitivity to the fading signal of the Gamma-ray Bursts.

  7. Resolving the Structure of Ionized Helium in the Intergalactic Medium with the Far Ultraviolet Spectroscopic Explorer. 2.3

    NASA Technical Reports Server (NTRS)

    Kriss, G. A.; Shull, J. M.; Oegerle, W.; Zheng, W.; Davidsen, A. F.; Songaila, A.; Tumlinson, J.; Cowie, L. L.; Dehavreng, J.-M.; Friedman, S. D.

    2001-01-01

    The neutral hydrogen and the ionized helium absorption in the spectra of high-redshift quasi-stellar objects (QSOs) are unique probes of structure in the universe at epochs intermediate between the earliest density fluctuations seen in the cosmic background radiation and the distribution of galaxies visible today. We present Far-Ultraviolet Spectroscopic Explorer (FUSE) observations of the line of sight to the QSO HE2347-4342 in the 1000-1187 angstrom band at a resolving power of 15,000. Above redshift z = 2.7, the IGM is largely opaque in He II Ly-alpha (304 angstroms). At lower redshifts, the optical depth gradually decreases to a mean value tau = 1 at z = 2.4. We resolve the He II Ly-alpha absorption as a discrete forest of absorption lines in the z = 2.3 - 2.7 redshift range. Approximately 50% of these spectral features have H I counterparts with column densities N(sub HI) > 10(exp 12.3)/sq cm visible in a Keck spectrum. These account for most of the observed opacity in He II Ly-alpha. The remainder have N(sub HI) < 10(exp 12.3)/sq cm, below the threshold for current observations. A short extrapolation of the power-law distribution of H I column densities to lower values can account for these new absorbers. The He II to H I column density ratio eta averages approximately 80, consistent with photoionization of the IGM by a hard ionizing spectrum resulting from the integrated light of quasars at high redshift, but there is considerable scatter. Values of eta > 100 in many locations indicate that there may be localized contributions from starbursts or heavily filtered QSO radiation.

  8. Simultaneous X-ray and Far-Ultraviolet Spectra of AGN with ASCA and HUT

    NASA Technical Reports Server (NTRS)

    Kriss, Gerard A.

    1997-01-01

    We obtained ASCA spectra of the Seyfert 1 galaxy NGC 3516 in March 1995. Simultaneous far-UV observations were obtained with the Hopkins Ultraviolet Telescope on the Astro-2 shuttle mission. The ASCA spectrum shows a lightly absorbed power law of energy index 0.78. The low energy absorbing column is significantly less than previously seen. Prominent 0 VII and 0 VIII absorption edges are visible, but, consistent with the much lower total absorbing column, no Fe K absorption edge is detectable. A weak, narrow Fe K(alpha) emission line from cold material is present as well as a broad Fe K(alpha) line. These features are similar to those reported in other Seyfert 1 galaxies. A single warm absorber model provides only an imperfect description of the low energy absorption. In addition to a highly ionized absorber with ionization parameter U = 1.66 and a total column density of 1.4 x 10(exp 22)/sq cm, adding a lower ionization absorber with U = 0.32 and a total column of 6.9 x 10(exp 21)/sq cm significantly improves the fit. The contribution of resonant line scattering to our warm absorber models limits the Doppler parameter to less than 160 km/s at 90% confidence. Turbulence at the sound speed of the photoionized gas provides the best fit. None of the warm absorber models fit to the X-ray spectrum can match the observed equivalent widths of all the UV absorption lines. Accounting for the X-ray and UV absorption simultaneously requires an absorbing region with a broad range of ionization parameters and column densities.

  9. Outburst of the 2 s Anomalous X-ray Pulsar 1E 1547.0-5408

    NASA Technical Reports Server (NTRS)

    Halpern, J. P.; Gotthelf, E. V.; Camilo, F.; Reynolds, J.; Ransom, S. M.

    2008-01-01

    Following our discovery of radio pulsations from the newly recognized anomalous X-ray pulsar (AXP) 1E 1547.0-5408, we initiated X-ray monitoring with the Swift X-ray telescope and obtained a single target-of-opportunity observation with the Newton X-ray Multi-Mirror Mission (XMM-Newton). In comparison with its historic minimum flux of 3 x 10(exp -l3)ergs/sq cm/s, the source was found to be in a record high state, f(sub x)(1-8 keV) = 5 x 10(exp -12)ergs/sq cm/s, or L(sub x) = 1.7 x 10(exp 35)(d/9 kpc )(sup 2)ergs/s, and declining by 25% in 1 month. Extrapolating the decay, we bound the total energy in this outburst to 1042 ergs < E < ergs. The spectra (fitted with a Comptonized blackbody) show that an increase in the temperature and area of a hot region, to 0.5 keV and -16% of the surface area of the neutron star, respectively, are primarily responsible for its increase in luminosity. The energy, spectrum, and timescale of decay are consistent with a deep crustal heating event, similar to an interpretation of the X-ray turn-on of the transient AXP XTE J18 10- 197. Simultaneous with the 4.6 hr ATdA4-Newton observation, we observed at 6.4 GHz with the Parkes telescope, measuring the phase relationship of the radio and X-ray pulse. The X-ray pulsed fraction of 1E 1547.0-5408 is only approx. 7 %, while its radio pulse is relatively broad for such a slow pulsar, which may indicate a nearly aligned rotator. As also inferred from the transient behavior of XTE J18 10-197, the only other AXP known to emit in the radio, the magnetic field rearrangement responsible for this X-ray outburst of 1E 1547.0-5408 is probably the cause of its radio turn-on.

  10. WISE Discovery of Hyper Luminous Galaxies at z=2-4 and Their Implications for Galaxy and AGN Evolution

    NASA Technical Reports Server (NTRS)

    Tsai, Chao Wei; Eisenhardt, Peter; Wu, Jingwen; Bridge, Carrie; Assef, Roberto; Benford, Dominic; Blain, Andrew; Cutri, Roc; Griffith, Robert L.; Jarrett, Thomas; Lonsdale, Carol; Petty, Sara; Sayers, Jack; Stanford, Adam; Stern, Daniel; Wright, Edward L.; Yan, Lin

    2014-01-01

    On behalf of the WISE Science team, we present the discovery of a class of distant dust-enshrouded galaxies with extremely high luminosity. These galaxies are selected to have extreme red colors in the mid-IR using NASA's Wide-field Infrared Survey Explorer (WISE). They are faint in the optical and near-IR, predominantly at zeta = 2-4, and with IR luminosity > 10(exp 13) Solar Luminosity, making them Hyper-Luminous Infrared Galaxies (HyLIRGs). SEDs incorporating the WISE, Spitzer, and Herschel PACS and SPIRE photometry indicate hot dust dominates the bolometric luminosity, presumably powered by AGN. Preliminary multi-wavelength follow-up suggests that they are different from normal populations in the local M-sigma relation. Their low source density implies that these objects are either intrinsically rare, or a short-lived phase in a more numerous population. If the latter is the case, these hot, dust-enshrouded galaxies may be an early stage in the interplay between AGN and galaxies.

  11. A calibration of the production rate ratio P-21/P-26 by low energy secondry neutrons: Identification of Ne spallation components at the 10(exp 6) atoms/g level in terrestrial samples

    NASA Technical Reports Server (NTRS)

    Graf, TH.; Niedermann, S.; Marti, K.

    1993-01-01

    The spallation ratio (Ne-22/Ne-21)(sub c) from Si was determined as 1.243 plus or minus 0.022 in a terrestrial quartz sample. We carried out a calibration of the in-situ production rate ratio P-21/P-26 in quartz samples for which Be-10 and Al-26 production rates were previously measured. A ratio P-21/P-26 of 0.67 plus or minus 0.12 is obtained.

  12. The Effect of Ultraviolet Radiation and Di-1-p-Menthene on the Phytotoxicity of 2,4-D Applications to Black Valentine Bean Plants

    DTIC Science & Technology

    dimer of beta - pinene ), the dimethylamine salt of (2,4- dichlorophenoxy)acetic acid, and the combination of the latter two. Greenhouse- grown bean...plants (Phaseolus vulgaris L. cv. Black Valentine) were exposed for various time periods to a mid-ultraviolet light source having a major emission peak at...254 nm. The energy level recorded at plant height was 350 ergs/sq cm/ sec. Plants exposed to this light source for 1 hr had chlorotic, malformed

  13. Evaluation of the effect of 4 types of knots on the mechanical properties of 4 types of suture material used in small animal practice.

    PubMed

    Avoine, Xytilis; Lussier, Bertrand; Brailovski, Vladimir; Inaekyan, Karine; Beauchamp, Guy

    2016-04-01

    The influence of the type of material used, knot configuration, and use of an additional throw on the tensile force at failure, the elongation, and the mode of failure of different configurations of linear sutures and knotted suture loops was evaluated in this in-vitro mechanical study. We hypothesized that all types of knots would significantly influence the initial force and elongation of suture materials and would influence the force and elongation at which the knotted loops break, but not their mode of failure. A total of 432 samples of 4 types of size 3-0 suture material (polydioxanone, polyglecaprone 25, polyglactin 910, and nylon), representing 9 configurations, were tested in a tensiometer. The configurations were 1 linear suture without a knot and the following loops: square (SQ) knot; surgeon's (SU) knot; granny (GR) knot; and sliding half-hitch (SHH) knot using either 4 and 5 or 3 and 4 throws, depending on the material. For polydioxanone, SQ and SU knots did not decrease the initial force at failure of the suture. Granny (GR) and SHH knots decreased the tensile force at failure and elongation by premature failure of the loop. For polyglecaprone 25, all knots decreased the initial force at failure of the suture, with SHH being weaker than the other knots. For coated polyglactin 910, all knots decreased the initial force at failure of the suture and slippage increased significantly compared with the other 3 sutures. The use of SQ knots with 3 throws did not result in a safe knot. For nylon, knots did not alter the original mechanics of the suture. In conclusion, all knots and types of suture material do not necessarily have the same effect on the initial tensile force at failure of suture materials.

  14. Dynamical timescales in the Jupiter family

    NASA Technical Reports Server (NTRS)

    Lindgren, Mats

    1992-01-01

    Numerically integrated fictitious comets starting in orbits perihelion tangent to Jupiter have been used to estimate the duration of a typical visit to the observable Jupiter family of comets. The results show values of 3 to 6 thousand years, narrowing the previously estimated interval of 10(exp 3) to 10(exp 4) years.

  15. The Einstein All-Sky IPC slew survey

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; Plummer, David; Fabbiano, G.

    1989-01-01

    The construction of the Einstein All-Sky Imaging Proportional Counter (IPC) slew survey is considered. It contains approximately 1000 sources between 10(exp -12) and 10(exp -10) erg/sq cm/s with a concentration toward the ecliptic poles and away from the galactic plane. Several sizable samples of bright soft X-ray selected objects for follow-up ROSAT and ASTRO-D observations and statistical study are presented. The survey source list is expected to be available by late 1989. Both paper and remote access online data base versions are to be available. An identification program is considered.

  16. Two new hot white dwarfs in a region of exceptionally low hi density

    NASA Technical Reports Server (NTRS)

    Barstow, M. A.; Wesemael, F.; Holberg, J. B.; Werner, K.; Buckley, D. A. H.; Stobie, R. S.; Fontaine, G.; Rosen, S. R.; Demers, S.; Lamontagne, R.

    1993-01-01

    We report the discovery of two hot white dwarfs which have the lowest line-of-sight neutral hydrogen column densities yet measured. The stars were found independently by the ROSAT EUV, Montreal-Cambridge-Tololo, and Edinburgh-Cape surveys. Follow-up observations made using the Voyager 2 ultraviolet spectrometer reveal strong continua shortward of the 912A Lyman limit from which we deduce that the neutral hydrogen column densities are 1.3 x 10(exp 17) and 2.0 x 10(exp 17) atoms/sq cm.

  17. Micro-Raman Analysis of Irradiated Diamond Films

    NASA Technical Reports Server (NTRS)

    Newton, Robert L.

    2003-01-01

    Owing to its unique and robust physical properties, diamond is a much sought after material for use in advanced technologies, even in Microelectromechanical Systems (MEMS). The volume and weight savings promised by MEMS-based devices are of particular interest to spaceflight applications. However, much basic materials science research remains to be completed in this field. Results of micro-Raman analysis of proton (10(exp 15) - 10(exp 17) H(+)/sq cm doses) irradiated chemical vapor deposited (CVD) films are presented and indicate that their microstructure is retained even after high radiation exposure.

  18. Carbon Nanotube Interconnect

    NASA Technical Reports Server (NTRS)

    Li, Jun (Inventor); Meyyappan, Meyya (Inventor)

    2006-01-01

    Method and system for fabricating an electrical interconnect capable of supporting very high current densities ( 10(exp 6)-10(exp 10) Amps/sq cm), using an array of one or more carbon nanotubes (CNTs). The CNT array is grown in a selected spaced apart pattern, preferably with multi-wall CNTs, and a selected insulating material, such as SiOw, or SiuNv is deposited using CVD to encapsulate each CNT in the array. An exposed surface of the insulating material is planarized to provide one or more exposed electrical contacts for one or more CNTs.

  19. On the Relationship Between High Speed Solar Wind Streams and Radiation Belt Electron Fluxes

    NASA Technical Reports Server (NTRS)

    Zheng, Yihua

    2011-01-01

    Both past and recent research results indicate that solar wind speed has a close connection to radiation belt electron fluxes [e.g., Paulikas and Blake, 1979; Reeves et aI., 2011]: a higher solar wind speed is often associated with a higher level of radiation electron fluxes. But the relationship can be very complex [Reeves et aI., 2011]. The study presented here provides further corroboration of this viewpoint by emphasizing the importance of a global perspective and time history. We find that all the events during years 2010 and 2011 where the >0.8 MeV integral electron flux exceeds 10(exp 5) particles/sq cm/sr/s (pfu) at GEO orbit are associated with the high speed streams (HSS) following the onset of the Stream Interaction Region (SIR), with most of them belonging to the long-lasting Corotating Interaction Region (CIR). Our preliminary results indicate that during HSS events, a maximum speed of 700 km/s and above is a sufficient but not necessary condition for the > 0.8 MeV electron flux to reach 10(exp 5) pfu. But in the exception cases of HSS events where the electron flux level exceeds the 10(exp 5) pfu value but the maximum solar wind speed is less than 700 km/s, a prior impact can be noted either from a CME or a transient SIR within 3-4 days before the arrival of the HSS - stressing the importance of time history. Through superposed epoch analysis and studies providing comparisons with the CME events and the HSS events where the flux level fails to reach the 10(exp 5) pfu, we will present the quantitative assessment of behaviors and relationships of various quantities, such as the time it takes to reach the flux threshold value from the stream interface and its dependence on different physical parameters (e.g., duration of the HSS event, its maximum or average of the solar wind speed, IMF Bz, Kp). The ultimate goal is to apply what is derived to space weather forecasting.

  20. A Multi-Wavelength Search for a Counterpart of the Unidentified Gamma-ray source 3EG J2020+4017 (2CG078+2)

    NASA Technical Reports Server (NTRS)

    Becker, Werner; Weisskopf, Martin C.; Arzoumanian, Zaven; Lorimer, Duncan; Camilo, Fernando; Elsner, Ronald F.; Kanbach, Gottfried; Reimer, Olaf; Swartz, Douglas A.; Tennant, Allyn F.

    2004-01-01

    In search of the counterpart to the brightest unidentified gamma-ray source 3EG J2020+4017 (2CG078+2) we report on new X-ray and radio observations of the gamma-Cygni field with the Chandra X-ray Observatory and with the Green Bank Telescope (GBT). We also report on reanalysis of archival ROSAT data. With Chandra it became possible for the first time to measure the position of the putative gamma-ray counterpart RX J2020.2+4026 with sub-arcsec accuracy and to deduce its X-ray spectral characteristics. These observations demonstrate that RX J2020.2+4026 is associated with a K field star and therefore is unlikely to be the counterpart of the bright gamma-ray source 2CG078+2 in the SNR G78.2+2.1 as had been previously suggested. The Chandra observation detected 37 additional X-ray sources which were correlated with catalogs of optical and infrared data. Subsequent GBT radio observations covered the complete 99% EGRET likelihood contour of 3EG J2020+4017 with a sensitivity limit of L(sub 820) approx. 0.1 mJy kpc(exp 2) which is lower than most of the recent deep radio search limits. If there is a pulsar operating in 3EG J2020+4017, this sensitivity limit suggests that the pulsar either does not produce significant amounts of radio emission or that its geometry is such that the radio beam does not intersect with the line of sight. Finally, reanalysis of archival ROSAT data leads to a flux upper limit of f(sub x)(0.1-2.4 keV) < 1.8 x 10(exp -13) erg/s/sq cm for a putative point-like X-ray source located within the 68% confidence contour of 3EG J2020+4017. Adopting the SNR age of 5400 yrs and assuming a spin-down to X-ray energy conversion factor of 10(exp -3) this upper limit constraints the parameters of a putative neutron star as a counterpart for 3EG J2020+4017 to be P > or approx. 160/(d/1.5 kpc) ms, P > or approx. 5 x 10(exp -13)/(d/1.5kpc) s s1 and B > or approx. 9 x 10(exp 12)/(d/1.5 kpc) G.

  1. Determination of Ground-Laboratory to In-Space Effective Atomic Oxygen Fluence for DC 93?500 Silicone

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Banks, Bruce A.; Ma, David

    2004-01-01

    The objective of this research was to calibrate the ground-to-space effective atomic oxygen fluence for DC 93-500 silicone in a thermal energy electron cyclotron resonance (ECR) oxygen plasma facility. Silicones, commonly used spacecraft materials, do not chemically erode with atomic oxygen attack like other organic materials but form an oxidized hardened silicate surface layer. Therefore, the effective atomic oxygen fluence in a ground test facility should not be determined based on mass loss measurements, as they are with organic polymers. A technique has been developed at the Glenn Research Center to determine the equivalent amount of atomic oxygen exposure in an ECR ground test facility to produce the same degree of atomic oxygen damage as in space. The approach used was to compare changes in the surface hardness of ground test (ECR) exposed DC 93-500 silicone with DC 93-500 exposed to low Earth orbit (LEO) atomic oxygen as part of a shuttle flight experiment. The ground to in-space effective atomic oxygen fluence correlation was determined based on the fluence in the ECR source that produced the same hardness for the fluence in-space. Nanomechanical hardness versus contact depth measurements were obtained for five ECR exposed DC 93-500 samples (ECR exposed for 18 to 40 hrs, corresponding to Kapton effective fluences of 4.2 x 10(exp 20) to 9.4 x 10(exp 20) atoms/sq cm, respectively) and for space exposed DC 93-500 from the Evaluation of Oxygen Interactions with Materials III (EOIM III) shuttle flight experiment, exposed to LEO atomic oxygen for 2.3 x 10(exp 20) atoms/sq cm. Pristine controls were also evaluated. A ground-to-space correlation value was determined based on correlation values for four contact depths (150, 200, 250, and 300 nm), which represent the near surface depth data. The results indicate that the Kapton effective atomic oxygen fluence in the ECR facility needs to be 2.64 times higher than in LEO to replicate equivalent exposure damage in the

  2. 'Heat from Above' Heat Capacity Measurements in Liquid He-4

    NASA Technical Reports Server (NTRS)

    Lee, R. A. M.; Chatto, A.; Sergatskov, D. A.; Babkin, A. V.; Boyd, S. T. P.; Churilov, A. M.; McCarson, T. D.; Chui, T. C. P.; Day, P. K.; Dunca, R. V.

    2003-01-01

    We have made heat capacity measurements of superfluid He-4 at temperatures very close to the lambda point, T(sub lambda) , in a constant heat flux, Q, when the helium sample is heated from above. In this configuration the helium enters a self-organized (SOC) heat transport state at a temperature T(sub SOC)(Q), which for Q greater than or = 100 nW/sq cm lies below T(sub lambda). At low Q we observe little or no deviation from the bulk Q = 0 heat capacity up to T(sub SOC)(Q); beyond this temperature the heat capacity appears to be sharply depressed, deviating dramatically from its bulk behaviour. This marks the formation and propagation of a SOC/superfluid two phase state, which we confirm with a simple model. The excellent agreement between data and model serves as an independent confirmation of the existence of the SOC state. As Q is increased (up to 6 micron W/sq cm) we observe a Q dependant depression in the heat capacity that occurs just below T(sub SOC)(Q), when the entire sample is still superfluid. This is due to the emergence of a large thermal resistance in the sample, which we have measured and used to model the observed heat capacity depression. Our measurements of the superfluid thermal resistivity are a factor of ten larger than previous measurements by Baddar et al.

  3. Stratospheric aerosols from CH4 photochemistry on Neptune

    NASA Technical Reports Server (NTRS)

    Romani, Paul N.; Atreya, Sushil K.

    1989-01-01

    A combined photochemical-condensation model has been used to study hydrocarbon ices produced from CH4 photolysis in the stratosphere of Neptune. A total stratospheric haze production rate of 4.2 x 10 to the -15th g/sq cm/s. The total production rate is insensitive to within a factor of two to order of magnitude changes in the eddy diffusion coefficient and methane mixing ratio, which is within the present estimate of uncertainty for this number. The condensation temperatures are 97 K for C4H2, 71 K for C2H2, and 64 K for C2H6. Voyager 2 images of Neptune will be able to confirm the presence of stratospheric aerosols and provide constraints on their production rate and location.

  4. Stratospheric aerosols from CH4 photochemistry on Neptune

    NASA Astrophysics Data System (ADS)

    Romani, P. N.; Atreya, S. K.

    1989-08-01

    A combined photochemical-condensation model has been used to study hydrocarbon ices produced from CH4 photolysis in the stratosphere of Neptune. A total stratospheric haze production rate of 4.2 x 10 to the -15th g/sq cm/s. The total production rate is insensitive to within a factor of two to order of magnitude changes in the eddy diffusion coefficient and methane mixing ratio, which is within the present estimate of uncertainty for this number. The condensation temperatures are 97 K for C4H2, 71 K for C2H2, and 64 K for C2H6. Voyager 2 images of Neptune will be able to confirm the presence of stratospheric aerosols and provide constraints on their production rate and location.

  5. Sea Ice Variability in the Sea of Okhotsk from Passive Microwave Satellite Observations

    NASA Technical Reports Server (NTRS)

    Cavalieri, Donald J.; Zukor, Dorothy (Technical Monitor)

    2000-01-01

    The Sea of Okhotsk, located between 50 and 60 N, is bounded by the Kamchatka Peninsula, Siberia, Sakhalin Island, and the Kuril Island chain and is the largest midlatitude seasonal sea ice zone in the Northern Hemisphere. The winter sea ice cover begins to form in November and expands to cover most of the sea by March. Over the following three months, the ice retreats with only small ice-covered areas remaining by the beginning of June. The sea is ice free or nearly ice free on average for six months of the year, from June through November. The recent compilation of a consistent, long-term record of Northern Hemisphere sea ice extents based on passive microwave satellite observations from the Nimbus 7 Scanning Multichannel Microwave Radiometer and from four Defense Meteorological Satellite Program Special Sensor Microwave Imagers provides the basis for assessing long-term sea ice extent variability in the Sea of Okhotsk. Analysis of this 20-year data record (1979-1998) shows that based on yearly averages the overall extent of the Sea of Okhotsk ice cover is decreasing at the rate of -8.1+/-2.1x10(exp 3) sq km/yr (-17.2%/decade), in contrast to the rate of decrease of -33.3+/-0.7x10(exp 3) sq km/yr (-2.7%/decade) for the Northern Hemisphere as a whole. There is large regional sea ice extent variability of the Arctic ice cover. Two of the nine Arctic regions analyzed, the Bering Sea and the Gulf of St. Lawrence, show increases of 0.8+/-1.4xl0(exp 3) sq km/yr (2.7%/decade) and 1.2+/-0.5xl0(exp 3) sq km/yr (17.1%/decade), respectively. Interestingly, the Sea of Okhotsk and the Gulf of St. Lawrence show about equal percentage changes, but of opposite sign. The Sea of Okhotsk exhibits its greatest percent decrease (-24.3%/decade) during spring (April-June). The year of maximum winter sea ice extent for the Sea of Okhotsk was 1979, whereas the minimum winter sea ice extent occurred in 1984.

  6. Coronal electron stream and Langmuir wave detection inside a propagation channel at 4.3 AU

    NASA Technical Reports Server (NTRS)

    Buttighoffer, A.; Pick, M.; Roelof, E. C.; Hoang, S.; Mangeney, A.; Lanzerotti, L. J.; Forsyth, R. J.; Phillips, J. L.

    1995-01-01

    Observations of an energetic interplanetary electron event associated with the production of Langmuir waves, both of which are identified at 4.3 AU by instruments on the Ulysses spacecraft, are presented in this paper. This electron event propagates inside a well-defined magnetic structure. The existence of this structure is firmly established by joint particle and plasma observations made by Ulysses instruments. Its local estimated radial width is of the order of 2.3 x 10(exp 7) km (0.15 AU). The electron beam is associated with a type III burst observed from Earth at high frequencies and at low frequencies from Ulysses in association with Langmuir waves detected inside the structure. The consistency of local (Ulysses) and remote (Earth) observations in terms of temporal and geometrical considerations establishes that the structure is anchored in the solar corona near the solar active region responisble for the observed type III emission and gives an accurate determination of the injection time for the observed electron beam. Propagation analysis of the electron event is presented. In order to quantify the magnetic field properties, a variance analysis has been performed and is presented in this paper. The analysis establishes that inside the structure the amount of magnetic energy involved in the fluctuations is less than 4% of the total magnetic energy; the minimal variance direction is well defined and in coincidence with the direction of the mean magnetic field. This configuration may produce conditions favorable for scatter free streaming of energetic electrons and/or Langmuir wave production. The results presented show that the magnetic field might play a role in stabilizing the coronal-origin plasma structures and then preserving them to large, approximately 4 AU, distances in the heliosphere.

  7. InP tunnel junction for InGaAs/InP tandem solar cells

    NASA Technical Reports Server (NTRS)

    Vilela, M. F.; Freundlich, A.; Bensaoula, A.; Medelci, N.; Renaud, P.

    1995-01-01

    Chemical beam epitaxy (CBE) has been shown to allow the growth of high quality materials with reproducible complex compositional and doping profiles. The main advantage of CBE compared to metalorganic chemical vapor deposition (MOCVD), the most popular technique for InP-based photovoltaic device fabrication, is the ability to grow high purity epilayers at much lower temperatures (450-530 C). We have previously shown that CBE is perfectly suited toward the fabrication of complex photovoltaic devices such as InP/InGaAs monolithically integrated tandem solar cells, because its low process temperature preserves the electrical characteristics of the InGaAs tunnel junction commonly used as an ohmic interconnect. In this work using CBE for the fabrication of optically transparent (with respect to the bottom cell) InP tunnel diodes is demonstrated. Epitaxial growth were performed in a Riber CBE 32 system using PH3 and TMIn as III and V precursors. Solid Be (p-type) and Si (n-type) have been used as doping sources, allowing doping levels up to 2 x 10(exp -19)/cu cm and 1 x 10(exp -19)/cu cm for n and p type respectively. The InP tunnel junction characteristics and the influence of the growth's conditions (temperature, growth rate) over its performance have been carefully investigated. InP p(++)/n(++) tunnel junction with peak current densities up to 1600 A/sq cm and maximum specific resistivities (V(sub p)/I(sub p) - peak voltage to peak current ratio) in the range of 10(exp -4) Omega-sq cm were obtained. The obtained peak current densities exceed the highest results previously reported for their lattice matched counterparts, In(0.53)Ga( 0.47)As and should allow the realization of improved minimal absorption losses in the interconnect InP/InGaAs tandem devices for Space applications. Owing to the low process temperature required for the top cell, these devices exhibit almost no degradation of its characteristics after the growth of subsequent thick InP layer suggesting

  8. Fall-Back Disks in Long and Short GRBS

    NASA Technical Reports Server (NTRS)

    Cannizo, John K.; Troja, E.; Gehrels, N.

    2011-01-01

    We present numerical time-dependent calculations for fall-back disks relevant for GRBs in which the disk of material surrounding the black hole (BH) powering the GRB jet modulates the mass flow, and hence the strength of the jet. Given the initial existence of a small mass appr oximately less than 10(exp -4) M(solar) near the progenitor with a circularization radius approximately 10(exp 10) - 10(exp 11) cm, an una voidable consequence will be the formation of an "external disk" whose outer edge continually moves to larger radii due to angular momentum transport and lack of a confining torque. For long GRBs, if the mass distribution in the initial fall-back disk traces the progenitor envelope, then a radius approximates 10(exp 11) cm gives a time scale app roximately 10(exp 4) s for the X-ray plateau. For late times t > 10(exp 7) s a steepening due to a cooling front in the disk may have obser vational support in GRB 060729. For short GRBs, one expects most of t he mass initially to lie at small radii < 10(exp 8) cm; however the presence of even a trace amount approximately 10(exp -9) M(solar) of hi gh angular material can give a brief plateau in the light curve.

  9. Canaveral National Seashore Water Quality and Aquatic Resource Inventory

    NASA Technical Reports Server (NTRS)

    Hall, C. R.; Provancha, J. A.; Oddy, D. M.; Lowers, R. L.; Drese, J. D.

    2001-01-01

    Mosquito Lagoon is a shallow, bar-built estuary located on the east central Florida Coast, primarily within the KSC boundary. The lagoon and watershed cover approximately 327 sq km (79422 acres) .The Lagoon occupies 159 sq km (37853 acres). Water depths average approximately 1m. The lagoon volume is approximately 1.6 x 10(exp 8)cu m. Water quality in Mosquito Lagoon is good. Salinity data typically range between 20 ppt and 35 ppt. The lowest value recorded was 4.5 ppt and the highest value was 37 ppt. Water temperatures fluctuate 2 - 3 C over a 24 h period. Cold front passage can rapidly alter water temperatures by 5 - 10 C or more in a short period of time. The highest temperature was 33.4 C and the lowest temperature was 8.8 C after a winter storm. Dissolved oxygen concentrations ranged from a low of 0.4 mg/l to a high of 15.3 mg/l. Extended periods of measurements below the Florida Department of Environmental Protection criteria of 4.0 mg/l were observed in fall and spring months suggesting high system respiration and oxygen demand. Metals such as antimony, arsenic, molybdenum and mercury were report as below detection limits for all samples. Cadmium, copper, chromium, silver, and zinc were found to be periodically above the Florida Department of Environmental Protection criteria for Class II and Class III surface waters.

  10. A study of gamma ray radiation at energies over 4 MeV by means of a large surface spark chamber

    NASA Astrophysics Data System (ADS)

    Lavigne, J.-M.

    The experimental design, apparatus, and results obtained with a 1 sq m sensing surface spark chamber for detecting gamma rays from the Agathe balloon payload are described. The sensing range of 4-100 MeV was attained with 15 1 sq m laminated 20-microns thick Ta plates. A mirror system provided a stereoscopic view of events and a means to photograph plate triggering along with the time of event. Photomultiplier tubes also monitored the scintillator plates. The instrument was placed in a polyamide enclosure and the interior pressure was lowered to 1 bar. The experiment was flown from Brasil in 1976 and 1977. The arrangement of the scintillators permitted differentiating between atmospheric and extra-atmospheric photons. The instrument was focused on the central galactic plane, and gamma ray photons detected were attributed to braking and the inverse Compton effect. The sources of the radiation are discussed with reference to simultaneously-acquired Cos B satellite data.

  11. Two-stage, low noise advanced technology fan. 4: Aerodynamic final report

    NASA Technical Reports Server (NTRS)

    Harley, K. G.; Keenan, M. J.

    1975-01-01

    A two-stage research fan was tested to provide technology for designing a turbofan engine for an advanced, long range commercial transport having a cruise Mach number of 0.85 -0.9 and a noise level 20 EPNdB below current requirements. The fan design tip speed was 365.8m/sec (1200ft/sec);the hub/tip ratio was 0.4; the design pressure ratio was 1.9; and the design specific flow was 209.2 kg/sec/sq m(42.85lbm/sec/sq ft). Two fan-versions were tested: a baseline configuration, and an acoustically treated configuration with a sonic inlet device. The baseline version was tested with uniform inlet flow and with tip-radial and hub-radial inlet flow distortions. The baseline fan with uniform inlet flow attained an efficiency of 86.4% at design speed, but the stall margin was low. Tip-radial distortion increased stall margin 4 percentage points at design speed and reduced peak efficiency one percentage point. Hub-radial distortion decreased stall margin 4 percentage points at all speeds and reduced peak efficiency at design speed 8 percentage points. At design speed, the sonic inlet in the cruise position reduced stall margin one percentage point and efficiency 1.5 to 4.5 percentage points. The sonic inlet in the approach position reduced stall margin 2 percentage points.

  12. Clouds, hazes, and the stratospheric methane abundance in Neptune

    NASA Technical Reports Server (NTRS)

    Baines, Kevin H.; Hammel, Heidi B.

    1994-01-01

    Analysis of high-spatial-resolution (approximately 0.8 arcsec) methane band and continuum imagery of Neptune's relatively homogeneous Equatorial Region yields significant constraints on (1) the stratospheric gaseous methane mixing ratio (f(sub CH4, S)), (2) the column abundances and optical properties of stratospheric and tropospheric hydrocarbon hazes, and (3) the wavelength-dependent single-scattering albedo of the 3-bar opaque cloud. From the center-to-limb behavior of the 7270-A and 8900-A CH4 bands, the stratospheric methane mixing ratios is limited to f(sub CH4, S) less than 1.7 x 10(exp -3), with a nominal value of f(sub CH4, S) = 3.5 x 10(exp -4), one to two orders of magnitude less than pre-Voyager estimates, but in agreement with a number of recent ultraviolet and thermal infrared measurements, and largely in agreement with the tropopause mixing ratio implied by Voyager temperature measurements. Upper limits to the stratospheric haze mass column abundance and 6190-A and 8900-A haze opacities are 0.61 micrograms/sq cm and 0.075 and 0.042, respectively, with nominal values of 0.20 micrograms/sq cm and 0.025 and 0.014 for the 0.2 micrometers radius particles preferred by the recent Voyager PPS analysis of Pryor et al. (1992). The tropospheric CH4 haze opacities are comparable to that found in the stratosphere, i.e., upper limits of 0.104 and 0.065 at 6190 A and 8900 A, respectively, with nominal values of 0.085 and 0.058. This indicates a column abundance less than 11.0 micrograms/sq cm, corresponding to the methane gas content within a well-mixed 3% methane tropospheric layer only 0.1 cm thick near the 1.5-bar CH4 condensation level. Conservative scattering is ruled out for the opaque cloud near 3 bars marking the bottom of the visible atmosphere. Specifically, we find cloud single-scattering albedos of 0.915 +/- 0.006 at 6340 A, 0.775 +/- 0.012 at 7490 A, and 0.803 +/- 0.010 at 8260 A. Global models utilizing a complete global spectrum confirm the red

  13. Overcoming Film Quality Issues for Conjugated Polymers Doped with F4TCNQ by Solution Sequential Processing: Hall Effect, Structural, and Optical Measurements.

    PubMed

    Scholes, D Tyler; Hawks, Steven A; Yee, Patrick Y; Wu, Hao; Lindemuth, Jeffrey R; Tolbert, Sarah H; Schwartz, Benjamin J

    2015-12-03

    We demonstrate that solution-sequential processing (SqP) can yield heavily doped pristine-quality films when used to infiltrate the molecular dopant 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) into pure poly(3-hexylthiophene) (P3HT) polymer layers. Profilometry measurements show that the SqP method produces doped films with essentially the same surface roughness as pristine films, and 2-D grazing-incidence wide-angle X-ray scattering (GIWAXS) confirms that SqP preserves both the size and orientation of the pristine polymer's crystallites. Unlike traditional blend-cast F4TCNQ/P3HT doped films, our sequentially processed layers have tunable and reproducible conductivities reaching as high as 5.5 S/cm even when measured over macroscopic (>1 cm) distances. The high conductivity and superb film quality allow for meaningful Hall effect measurements, which reveal p-type conduction and carrier concentrations tunable from 10(16) to 10(20) cm(-3) and hole mobilities ranging from ∼0.003 to 0.02 cm(2) V(-1) s(-1) at room temperature over the doping levels examined.

  14. 2.4 Micrometer Cutoff Wavelength AlGaAsSb/InGaAsSb Phototransistors

    NASA Technical Reports Server (NTRS)

    Sulima, O. V.; Swaminathan, K.; Refaat, T. F.; Faleev, N. N.; Semenov, A. N.; Solov'ev, V. A.; Ivanov, S. V.; Abedin, M. N.; Singh, U. N.; Prather, D.

    2006-01-01

    We report the first AlGaAsSb/InGaAsSb phototransistors with a cutoff wavelength (50% of peak responsivity) of 2.4 micrometers operating in a broad range of temperatures. These devices are also the first AlGaAsSb/InGaAsSb heterojunction phototransistors (HPT) grown by molecular beam epitaxy (MBE). This work is a continuation of a preceding study, which was carried out using LPE (liquid phase epitaxy)-grown AlGaAsSb/InGaAsSb/GaSb heterostructures. Although the LPE-related work resulted in the fabrication of an HPT with excellent parameters [1-4], the room temperature cutoff wavelength of these devices (approximately 2.15 micrometers) was determined by fundamental limitations implied by the close-to-equilibrium growth from Al-In-Ga-As-Sb melts. As the MBE technique is free from the above limitations, AlGaAsSb/InGaAsSb/GaSb heterostructures for HPT with a narrower bandgap of the InGaAsSb base and collector - and hence sensitivity at longer wavelengths (lambda) - were grown in this work. Moreover, MBE - compared to LPE - provides better control over doping levels, composition and width of the AlGaAsSb and InGaAsSb layers, compositional and doping profiles, especially with regard to abrupt heterojunctions. The new MBE-grown HPT exhibited both high responsivity R (up to 2334 A/W for lambda=2.05 micrometers at -20 deg C.) and specific detectivity D* (up to 2.1 x 10(exp 11) cmHz(exp 1/2)/W for lambda=2.05 micrometers at -20 deg C).

  15. Evidence for Live Cl-36 in Ca-Al-rich Inclusions from the Ningqiang Carbonaceous Chondrite

    NASA Technical Reports Server (NTRS)

    Lin, Y.; Guan, Y.; Leshin, L. A.; Ouyang, Z.; Wang, D.

    2004-01-01

    The short-lived radionuclide Cl-36 decays to either Ar-36 (98.1%, beta(sup -)) or S-36 (1.9%, epsilon and beta(sup +)), with a half life of 3.01 x 10(exp 5) yr. Both the nucleosynthetic and spallation models suggest high initial Cl-36/Cl-35 ratios ((Cl-36/Cl-35)o up to approximately 10(exp -4)) in the early solar system. Previous observed excess Ar-36 in Efremovka matrix has been interpreted to represent a much lower (Cl-36/Cl-35)o ratio of approximately 1 x 10(exp -6). From the observed S-36 excesses in sodalite in calcium aluminum-rich inclusions (CAIs), we report in this study the first direct evidence of the presence of Cl-36 in primitive meteorites. The inferred (Cl-36/Cl-35)o ratios range from approximately 5 x 10(exp -6) to approximately 1 x 10(exp -5).

  16. A search for massive compact halo objects in our Galaxy

    NASA Astrophysics Data System (ADS)

    Bennett, D. P.; Alcock, C.; Axelrod, T.; Cook, K.; Park, H.; Griest, K.; Stubbs, C.; Freeman, K.; Peterson, B.; Quinn, P.; Rogers, A.

    1991-04-01

    Massive compact halo objects such as brown dwarfs, Jupiters, and black holes are prime candidates to comprise the dark halo of our galaxy. Our group is currently involved in constructing a dedicated observing system at the Mount Stromlo Observatory in Australia. We will use a refurbished 1.27 meter telescope and an innovative two-color CCD camera with 3.4 x 10 exp 7 pixels to monitor 10 exp 6 - 10 exp 7 stars in the Magellanic Clouds. During the first year of operation (1991-1992), we hope to detect (or rule out) objects in the mass range between 0.001 and 0.1 solar mass, and after five years, we hope to have covered the range 10 exp -6 solar mass - 10 exp 2 solar masses.

  17. Experimental Surface Pressure Data Obtained on 65 deg Delta Wing Across Reynolds Number and Mach Number Ranges. Vol. 3: Medium-radius leading edge

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Luckring, James M.

    1996-01-01

    An experimental wind tunnel test of a 65 deg delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 120 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6), 60 x 10(exp 6), and 120 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.

  18. Relic gravitational waves and extended inflation

    NASA Technical Reports Server (NTRS)

    Turner, Michael S.; Wilczek, Frank

    1990-01-01

    In extended inflation, a new version of inflation where the transition from the false-vacuum phase to a radiation-dominated Universe is accomplished by bubble nucleation and percolation, bubble collisions supply a potent-and potentially detectable-source of gravitational waves. The present energy density in relic gravity waves from bubble collisions is expected to be about 10(exp -5) of closure density-many orders of magnitude greater than that of the gravity waves produced by quantum fluctuations. Their characteristic wavelength depends upon the reheating temperature T(sub RH): lambda is approximately 10(exp 4) cm (10(exp 14) GeV/T(sub RH)). If large numbers of black holes are produced, a not implausible outcome, they will evaporate producing comparable amounts of shorter wavelength waves, lambda is approximately 10(exp -6) cm (T(sub RH)/10(exp 14) GeV).

  19. Direct detection optical intersatellite link at 220 Mbps using AlGaAs laser diode and silicon APD with 4-ary PPM signaling

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Davidson, Frederic M.

    1990-01-01

    A newly developed 220 Mbps free-space 4-ary pulse position modulation (PPM) direct detection optical communication system is described. High speed GaAs integrated circuits were used to construct the PPM encoder and receiver electronic circuits. Both PPM slot and word timing recovery were provided in the PPM receiver. The optical transmitter consisted of an AlGaAs laser diode (Mitsubishi ML5702A, lambda=821nm) and a high speed driver unit. The photodetector consisted of a silicon avalanche photodiode (APD) (RCA30902S) preceded by an optical interference filter (delta lambda=10nm). Preliminary tests showed that the self-synchronized PPM receiver could achieve a receiver bit error rate of less than 10(exp -6) at 25 nW average received optical signal power or 360 photons per transmitted information bit. The relatively poor receiver sensitivity was believed to be caused by the insufficient electronic bandwidth of the APD preamplifier and the poor linearity of the preamplifier high frequency response.

  20. High-temperature photochemistry and BAC-MP4 studies of the reaction between ground-state H atoms and N/sub 2/O

    SciTech Connect

    Marshall, P.; Fontijn, A.; Melius, C.F.

    1987-05-15

    The H+N/sub 2/O reaction has been investigated using the high-temperature photochemistry (HTP) technique. H(1 /sup 2/S) atoms were generated by flash photolysis of NH/sub 3/ and monitored by time-resolved atomic resonance fluorescence with pulse counting. The bimolecular rate coefficient for H-atom consumption, leading essentially to N/sub 2/+OH, from 390 to 1310 K is found to be given by k/sub 1/(T) = 5.5 x 10/sup -14/ exp(-2380 K/T)+7.3 x 10/sup -10/ exp(-9690 K/T) cm/sup 3/ molecule/sup -1/ s/sup -1/; the accuracy is assessed as approximately 25% at the 2sigma confidence level. Above 750 K, k/sub 1/ closely follows the Arrhenius behavior of the second term alone. Distinct curvature is evident below 750 K. k/sub 1/ is compared to theoretical BAC-MP4 predictions and good agreement is found for a model involving rearrangement of an HNNO intermediate coupled with tunneling through an Eckart potential barrier, which dominates at the lower temperatures. The branching ratio for the channel leading to NH+NO is discussed in the context of recent thermochemical information and a maximum rate coefficient of <1 x 10/sup -9/ exp(-15800 K/T) cm/sup 3/ molecule/sup -1/ s/sup -1/ is set for temperatures up to 2000 K.

  1. The Titan haze revisted: Magnetospheric energy sorces quantitative tholin yields

    NASA Technical Reports Server (NTRS)

    Thompson, W. Reid; Mcdonald, Gene D.; Sagan, Carl

    1994-01-01

    We present laboratory measurements of the radiation yields of complex organic solids produced from N2/CH4 gas mixtures containing 10 or 0.1% CH4. These tholins are thought to resemble organic aerosols produced in the atmospheres of Titan, Pluto, and Triton. The tholin yields are large compared to the total yield of gaseous products: nominally, 13 (C + N)/100 eV for Titan tholin and 2.1 (C + N)/100 eV for Triton tholin. High-energy magnetospheric electrons responsible for tholin production represents a class distinct from the plasma electrons considered in models of Titan's aiglow. Electrons with E greater than 20 keV provide an energy flux approximately 1 x 10(exp -2) erg/cm/sec, implying from our measured tholin yields a mass flux of 0.5 to 4.0 x 10(exp -14) g/sq cm/sec of tholin. (The corresponding thickness of the tholin sedimentary column accumulated over 4 Gyr on Titan's surface is 4 to 30 m). This figure is in agreement with required mass fluxes computed from recent radiative transfer and sedimentation models. If, however, theses results, derived from experiments at approximately 2 mb, are applied to lower pressure levels toward peak auroral electron energy deposition and scaled with pressure as the gas-phase organic yields, the derived tholin mass flux is at least an order of magnitude less. We attrribute this difference to the fact that tholin synthesis occurs well below the level of maximum electron energy depositon and to possible contributions to tholis from UV-derived C2-hydrocarbons. We conclude that Tita tholin, produced by magnetospheric electrons, is alone sufficient to supply at least a significant fraction of Titan's haze-a result consistent with the fact that the optical properties of Titan tholin, among all proposed material, are best at reproducing Titan's geometric albedo spectrum from near UV to mid-IR in light-scattering models.

  2. Fabrication of sub-40-nm p-n junctions for 0.18 micron MOS device applications using a cluster-tool-compatible, nanosecond thermal doping technique

    NASA Astrophysics Data System (ADS)

    Weiner, K. H.; McCarthy, A. M.

    1993-09-01

    In this paper, we introduced an alternative deep-submicrometer doping technology, Projection Gas Immersion Laser Doping (P-GILD). Representing the marriage of lithography and diffusion, P-GILD is a resistless, step-and-repeat doping process that utilizes excimer laser light patterned by a dielectric reticle to selectively heat and, thereby, dope regions of an integrated circuit. Results of physical and electrical characterization are presented for ultra-shallow p(sup +) (minus)n and n(sup +) (minus)p junctions produced by gas immersion laser doping (GILD), a phenomenologically identical technique that utilizes an aluminum contact mask rather than a dielectric reticle to pattern the beam. Junctions produced using GILD exhibit uniformly-doped, abrupt impurity profiles with no apparent defect formation in the silicon. Electrically, sheet and contact resistivities of the ultra-shallow junctions are less than 100(Omega)/sheet and 1 x 10(exp -6) (Omega)*sq cm, respectively, while n(sup +) (minus)p and p(sup +) (minus)n diodes exhibit nearly ideal forward bias behavior and reverse leakage current densities less than 5 nA/sq cm at -5V. Uniformity of both diode characteristics and sheet resistance for junctions produced by the step-and-repeat process is also shown to be better than (plus minus)5% across a 4-inch wafer.

  3. The Complex Spin State of 103P-Hartley 2: Kinematics and Orientation in Space

    NASA Technical Reports Server (NTRS)

    Belton, Michael J. S.; Thomas, Peter; Li, Jian-Yang; Williams, Jade; Carcich, Brian; A'Hearn, Michael F.; McLaughlin, Stephanie; Farnham, Tony; McFadden, Lucy; Lisse, Carey M.; Collins, Steven; Besse, Sebastien; Klaasen, Kenneth; Sunshine, Jessica; Meech, Karen J.; Lindler, Don

    2013-01-01

    We derive the spin state of the nucleus of Comet 103P/Hartley 2, its orientation in space, and its short-term temporal evolution from a mixture of observations taken from the DIXI (Deep Impact Extended Investigation) spacecraft and radar observations. The nucleus is found to spin in an excited long-axis mode (LAM) with its rotational angular momentum per unit mass, M, and rotational energy per unit mass, E, slowly decreasing while the degree of excitation in the spin increases through perihelion passage. M is directed toward (RA, Dec; J2000) = 8+/-+/- 4 deg., 54 +/- 1 deg. (obliquity = 48 +/- 1 deg.). This direction is likely changing, but the change is probably <6 deg. on the sky over the approx. 81.6 days of the DIXI encounter. The magnitudes of M and E at closest approach (JD 2455505.0831866 2011-11-04 13:59:47.310) are 30.0 +/- 0.2 sq. m/s and (1.56 +/- 0.02) X 10(exp -3) sq. m /sq. s respectively. The period of rotation about the instantaneous spin vector, which points in the direction (RA, Dec; J2000) = 300 +/- 3.2deg., 67 +/- 1.3 deg. at the time of closest approach, was 14.1 +/- 0.3 h. The instantaneous spin vector circulates around M, inclined at an average angle of 33.2 +/- 1.3 deg. with an average period of 18.40 +/- 0.13 h at the time of closest approach. The period of roll around the principal axis of minimum inertia (''long'' axis) at that time is 26.72 +/- 0.06 h. The long axis is inclined to M by approx. 81.2 +/- 0.6 deg. on average, slowly decreasing through encounter. We infer that there is a periodic nodding motion of the long axis with half the roll period, i.e., 13.36+/- 0.03 h, with amplitude of 1 again decreasing through encounter. The periodic variability in the circulation and roll rates during a cycle was at the 2% and 10-14% level respectively. During the encounter there was a secular lengthening of the circulation period of the long axis by 1.3 +/- 0.2 min/d, in agreement with ground-based estimates, while the period of roll around the

  4. Nitrogen sulfide in quiescent dark clouds

    NASA Technical Reports Server (NTRS)

    Mcgonagle, Douglas; Irvine, William M.; Ohishi, Masatoshi

    1994-01-01

    We report the first detection of interstellar nitrogen sulfide (NS) in cold dark clouds. Several components of the (2)Pi(sub 1/2), J = 3/2 to 1/2 and J = 5/2 to 3/2 transitions were observed in TMC-1 and L134N. The inferred column density for TMC-1 is N(sub NS) approximately 8 x 10(exp 12)/sq cm toward the NH3 peak in that cloud, and in L134N is N(sub NS) approximately 3 x 10(exp 12)/sq cm toward the position of peak NH3 emission. These values correspond to fractional abundances relative to molecular hydrogen of f(sub NS) approximately 8 x 10(exp -10) for TMC-1, and f(sub NS) approximately 6 x 10(exp -10) for L134N. The NS emission is extended along the TMC-1 ridge and is also extended in L134N. The measured abundances are significantly higher than those predicted by some recent gas phase ion-molecule models.

  5. The Observed Galactic Annihilation Line: Possible Signature of Accreting Small Mass Black Holes in the Galactic Center

    NASA Technical Reports Server (NTRS)

    Titarchuk, Lev; Chardonnet, Pascal

    2006-01-01

    Various balloon and satellite observatories have revealed what appears to be an extended source of 0.511 MeV annihilation radiation with flux of approx. 10(exp -3) photons/sq cm/s centered on the Galactic Center. Positrons from radioactive products of stellar explosions can account for a significant fraction of the emission. We discuss an additional source for this emission: namely e(+)e(-) pairs produced when X-rays generated from the approx. 2.6 x 10(exp 6) solar mass Galactic Center Black Hole interact with approx. 10 MeV temperature blackbody emission from 10(exp 17) g black holes within 10(exp 14-l5) cm of the center. The number of such Small Mass Black Holes (SMMBHs) can account for the production of the 10(exp 42) e(+)/s that produces the observed annihilation in the inner Galaxy when transport effects are taken into account. We consider the possibility for confirming the presence of these SMMBHs in the Galactic Center region with future generations of gamma-ray instruments if a blackbody like emission of approx. 10 MeV temperature would be detected by them. Small Mass Black Hole can be a potential candidate for dark (invisible) matter hal

  6. The z~4 Quasar Luminosity Function: Implications for supermassive black hole growth, reionization, and future time domain surveys

    NASA Astrophysics Data System (ADS)

    AlSayyad, Yusra; Connolly, Andrew J.; McGreer, Ian D.; Ivezic, Zeljko; Fan, Xiaohui; LSST Data Management

    2017-01-01

    Upcoming time-domain imaging surveys such as the LSST will detect over a million high-redshift (z > 4) quasars, making complete spectroscopic followup unfeasible. Statistical estimates such as luminosity functions and clustering measurements will require purely photometric methods for classifying objects, estimating redshifts and estimating selection functions. We develop these methods and constrain the optical, type I quasar luminosity function (QLF) at 3.75 < z < 4.5 for -27.5 < M1450 < -23.5. Using the Sloan Digital Sky Survey (SDSS) repeated imaging of the 275 sq. deg. equatorial region of the sky (50 < R.A. < +60; -1.26 < Dec. < +1.26) known as Stripe 82, we extracted 40 million new lightcurves using the LSST data management software and selected a statistical sample of z~4 quasars based on colors and variability metrics. We confirmed these using a spectroscopically complete 55 sq. deg. sub-region augmented with 102 new spectroscopic observations of quasars at z > 3.4 with i < 22.5. We present the first variability-selected QLF measurement at high redshift (z > 3.75) and constraint on the characteristic luminosity M*1450 = -26.7 from a single, uniformly-selected survey at z~4.

  7. Concept Development of a Mach 2.4 High-Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    Fenbert, James W.; Ozoroski, Lori P.; Geiselhart, Karl A.; Shields, Elwood W.; McElroy, Marcus O.

    1999-01-01

    In support of the NASA High-Speed Research Program, a Mach 2.4 high-speed civil transport concept was developed to serve as a baseline for studies to assess advanced technologies required for a feasible year 2005 entry-into-service vehicle. The configuration was designed to carry 251 passengers at Mach 2.4 cruise with a 6500-n.mi. range and operate in the existing world airport structure. The details of the configuration development, aerodynamic design, propulsion system and integration, mass properties, sizing, and mission performance are presented. The baseline configuration has a wing area of 9l00 sq ft and a takeoff gross weight of 614300 lb. The four advanced turbine bypass engines have 39 000 lb thrust with a weight of 9950 lb each, yielding a vehicle takeoff thrust-to-weight ratio of 0.254 and a takeoff wing loading of 67.5 lb/sq ft. The configuration was sized by the 11000-ft takeoff field length requirement and the usable fuel volume limit, which results in a rotation speed of 179 knots and an end-of-mission landing approach velocity of 134 knots.

  8. Chandra Deep X-ray Observation of a Typical Galactic Plane Region and Near-Infrared Identification

    NASA Technical Reports Server (NTRS)

    Ebisawa, K.; Tsujimoto, M.; Paizis, A.; Hamaguichi, K.; Bamba, A.; Cutri, R.; Kaneda, H.; Maeda, Y.; Sato, G.; Senda, A.

    2004-01-01

    Using the Chandra Advanced CCD Imaging Spectrometer Imaging array (ACIS-I), we have carried out a deep hard X-ray observation of the Galactic plane region at (l,b) approx. (28.5 deg,0.0 deg), where no discrete X-ray source has been reported previously. We have detected 274 new point X-ray sources (4 sigma confidence) as well as strong Galactic diffuse emission within two partidly overlapping ACIS-I fields (approx. 250 sq arcmin in total). The point source sensitivity was approx. 3 x 10(exp -15)ergs/s/sq cm in the hard X-ray band (2-10 keV and approx. 2 x 10(exp -16) ergs/s/sq cm in the soft band (0.5-2 keV). Sum of all the detected point source fluxes account for only approx. 10 % of the total X-ray fluxes in the field of view. In order to explain the total X-ray fluxes by a superposition of fainter point sources, an extremely rapid increase of the source population is required below our sensitivity limit, which is hardly reconciled with any source distribution in the Galactic plane. Therefore, we conclude that X-ray emission from the Galactic plane has truly diffuse origin. Only 26 point sources were detected both in the soft and hard bands, indicating that there are two distinct classes of the X-ray sources distinguished by the spectral hardness ratio. Surface number density of the hard sources is only slightly higher than observed at the high Galactic latitude regions, strongly suggesting that majority of the hard X-ray sources are active galaxies seen through the Galactic plane. Following the Chandra observation, we have performed a near-infrared (NIR) survey with SOFI at ESO/NTT to identify these new X-ray sources. Since the Galactic plane is opaque in NIR, we did not see the background extragalactic sources in NIR. In fact, only 22 % of the hard sources had NIR counterparts which are most likely to be Galactic origin. Composite X-ray energy spectrum of those hard X-ray sources having NIR counterparts exhibits a narrow approx. 6.7 keV iron emission line, which

  9. A dc-coupled, high sensitivity bolometric detector system for the Infrared Telescope in Space

    NASA Technical Reports Server (NTRS)

    Devlin, M.; Lange, A. E.; Wilbanks, T.; Sato, S.

    1993-01-01

    We report the performance of an ac bridge readout system that has been developed for use on the Infrared Telescope in Space which is scheduled for launch in 1994. The ac bridge readout provides excellent dc stability enabling observing strategies well-suited to space-borne observations. The ability to modulate the optical signal slowly allows the use of new, highly sensitive, long time-constant bolometers. At 300 mK, the bolometers have an electrical noise equivalent power of 3 x 10 exp -17 W/sq rt Hz. The total noise of the differential signal, including amplifier noise, is less than 8 x 10 exp -17 W/sq rt Hz at frequencies as low as 35 mHz.

  10. Microwave background anisotropies implied by large-scale galaxy correlations - The minimum of C(0) and cosmological parameters

    NASA Technical Reports Server (NTRS)

    Kashlinsky, A.

    1991-01-01

    Data from a recent APM survey are used to show that large-scale galaxy correlations found there imply the existence of measurable microwave background radiation (MBR) anisotropies on scales greater than several degrees. It is shown that sq rt C(0) is not less than 3.5 x 10 exp -5 if the APM data are used at Theta-0 = 20 deg, or sq rt C(0) is not less than 2.8 x 10 exp -5 if Theta-0 = 10 deg is used. These numbers are almost independent of the cosmological parameters Omega, Lambda, and the redshift of the last scattering surface. For finite-beamwidth experiments the minimal fluctuations depend on the cosmological parameters. The minimal anisotropies are smaller in a low-Omega universe.

  11. Flight- and ground-test correlation study of BMDO SDS materials: Phase 1 report

    NASA Technical Reports Server (NTRS)

    Chung, Shirley Y.; Brinza, David E.; Minton, Timothy K.; Stiegman, Albert E.; Kenny, James T.; Liang, Ranty H.

    1993-01-01

    The NASA Evaluation of Oxygen Interactions with Materials-3 (EOIM-3) experiment served as a test bed for a variety of materials that are candidates for Ballistic Missile Defense Organization (BMDO) space assets. The materials evaluated on this flight experiment were provided by BMDO contractors and technology laboratories. A parallel ground exposure evaluation was conducted using the FAST atomic-oxygen simulation facility at Physical Sciences, Inc. The EOIM-3 materials were exposed to an atomic oxygen fluence of approximately 2.3 x 10(exp 2) atoms/sq. cm. The ground-exposed materials' fluence of 2.0 - 2.5 x 10(exp 2) atoms/sq. cm permits direct comparison of ground-exposed materials' performance with that of the flight-exposed specimens. The results from the flight test conducted aboard STS-46 and the correlative ground exposure are presented in this publication.

  12. Timing Noise in SGR 1806-20

    NASA Technical Reports Server (NTRS)

    Woods, Peter M.; Kouveliotou, Chryssa; Finger, Mark H.; Gogus, Ersin; Scott, D. Matthew; Dieters, Stefan; Thompson, Christopher; Duncan, Robert C.; Hurley, Kevin; Strohmayer, Tod

    2000-01-01

    We have phase connected a sequence of Rossi X-ray Timing Explorer Proportional Counter Array observations of SGR 1806-20 covering 178 days. We find a simple secular spin-down model does not adequately fit the data. The period derivative varies gradually during the observations between 8.1 and 11.7 x 10(exp -11) s/s (approx. 40% larger than the long term trend), while the average burst rate as seen with the Burst and Transient Source Experiment drops throughout the time interval. The phase residuals show no evidence for periodicity, but more closely resemble timing noise as seen ill radio pulsars. The magnitude of the timing noise., however, is large relative to the noise level typically found in radio pulsars (Delta(sub 8) = 4.8; frequency derivative average power approx. = 8 X 10(exp -20) Hz/sq s). Combined with the noise levels measured for some AXPs. we find all magnetar candidates have A8 values larger than those expected from a simple extrapolation of the correlation found in radio pulsars. We find the timing noise ill SGR 1806-20 is greater than or equal to the levels found in some accreting systems (e.g., Vela X-1, 4U 1538-52 and 4U 1626-67). Alternatively, an orbital model with a period P(sub orb) = 733 days provides a statistically acceptable fit to the data. If the phase residuals are created by Doppler shifts from a gravitationally bound companion. then the allowed parameter space for the mass function (small) and orbital separation (large) rule out the possibility of accretion from the companion sufficient to power the persistent emission from the SGR.

  13. The Infrared Properties of Sources Matched in the Wise All-Sky and Herschel ATLAS Surveys

    NASA Technical Reports Server (NTRS)

    Bond, Nicholas A.; Benford, Dominic J.; Gardner, Jonathan P.; Amblard, Alexandre; Fleuren, Simone; Blain, Andrew W.; Dunne, Loretta; Smith, Daniel J. B.; Maddox, Steve J.; Hoyos, Carlos; Auld, Robbie; Bales, Maarten; Bonfield, David; Bourne, Nathan; Bridge, Carrie; Buttiglione, Sara; Cava, Antonio; Clements, David; Cooray, Asantha; Dariush, Ali; deZotti, Gianfranco; Driver, Simon; Tsai, Chao-Wei; Wright, Edward L.; Yan, Lin

    2012-01-01

    We describe the infrared properties of sources detected over approx 36 sq deg of sky in the GAMA 15-hr equatorial field, using data from both the Herschel Astrophysical Terahertz Large-Area Survey (HATLAS) and Wide-field Infrared Survey (WISE). With 5sigma point-source depths of 34 and 0.048 mJy at 250 micron and 3.4 micron, respectively, we are able to identify 50.6% of the H-ATLAS sources in the WISE survey, corresponding to a surface density of approx 630 deg(exp -2). Approximately two-thirds of these sources have measured spectroscopic or optical/near-IR photometric redshifts of z < 1. For sources with spectroscopic redshifts at z < 0.3, we find a linear correlation between the infrared luminosity at 3.4 micron and that at 250 micron, with +/- 50% scatter over approx 1.5 orders of magnitude in luminosity, approx 10(exp 9) - 10(exp 10.5) Solar Luminosity By contrast, the matched sources without previously measured redshifts (r approx > 20.5) have 250-350 micron flux density ratios that suggest either high-redshift galaxies (z approx > 1.5) or optically faint low-redshift galaxies with unusually low temperatures (T approx < 20). Their small 3.4-250 micron flux ratios favor a high-redshift galaxy population, as only the most actively star-forming galaxies at low redshift (e.g., Arp 220) exhibit comparable flux density ratios. Furthermore, we find a relatively large AGN fraction (approx 30%) in a 12 micron flux-limited subsample of H-ATLAS sources, also consistent with there being a significant population of high-redshift sources in the no-redshift sample

  14. Evidence for Orbital Decay of RX J1914.4+2456: Gravitational Radiation and the Nature of the X-Ray Emission

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    RX J1914.4+2456 is a candidate double-degenerate binary (AM CVn) with a putative 569 s orbital period. If this identification is correct, then it has one of the shortest binary orbital periods known, and gravitational radiation should drive the orbital evolution and mass transfer if the binary is semi-detached. Here we report the results of a coherent timing study of the archival ROSAT data for RX J1914.4+2456. We performed a phase coherent timing analysis using all five ROSAT observations spanning a four-year period. We demonstrate that all the data can be phase connected, and we show that the 1.756 mHz orbital frequency is increasing at a rate of 1.5 +/- 0.4 x 10(exp -17) Hz/s consistent with the expected loss of angular momentum from the binary system via gravitational radiation. In addition to providing evidence for the emission of gravitational waves, our measurement of the orbital v(dot) constrains models for the X-ray emission and the nature of the secondary. If stable mass accretion drives the X-ray flux, then a positive v(dot) is inconsistent with a degenerate donor. A helium burning dwarf is compatible if indeed such systems can have periods as short as that of RX J1914.4+2456, an open theoretical question. Our measurement of a positive v(dot) is consistent with the unipolar induction model of Wu et al. which does not require accretion to drive the X-ray flux. We discuss how future timing measurements of RX J1914.4+2456 (and systems like it) with for example, Chandra and XMM-Newton, can provide a unique probe of the interaction between mass loss and gravitational radiation. We also discuss the importance of such measurements in the context of gravitational wave detection from space, such as is expected in the future with the LISA mission.

  15. The Composition of Titan's Lower Atmosphere and Simple Surface Volatiles as Measured by the Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer Experiment

    NASA Technical Reports Server (NTRS)

    Niemann, H. B.; Atreya, S. K.; Demick, J. E.; Gautier, D.; Haberman, J. A.; Harpold, D. N.; Kasprzak, W. T.; Lunine, J. I.; Owen, T. C.; Raulin, F.

    2010-01-01

    The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from 140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  16. Environmental Perturbations Caused by the Impacts of Comets and Asteroids on Earth

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Lawless, James G. (Technical Monitor)

    1994-01-01

    The extinction mechanisms proposed at the Cretaceous-Tertiary geological boundary are reviewed and related to the impact of asteroids or comets in general. For impact energies below 10(exp 4) Megatons (less than 6 x 10(exp 4) years; asteroid diameter less than 650 m), blast, earthquake, and fire may destroy local areas up to 10(exp 5) square m. Tidal waves could flood a kilometer inland over entire ocean basins. The energy range from 105 to 106 Megatons (less than 2 x 10(exp 6) years; asteroid diameter less than 3 km) is transitional. Dust lifted, sulfur released from within impacting asteroids, and soot from fires started by comets can produce climatologically significant optical depths of 10. At energies beyond 10(exp 7) Megatons, blast and earthquake damage is regional (10(exp 6) square cm). Tsunami cresting to 100 m and flooding 20 km inland will sweep the coastal zones of the world's oceans. Fires will be set globally. Light levels may drop so low from the smoke, dust and sulfate that vision is not possible. At energies approaching 10(exp 9) Megatons the ocean surface waters may be acidified by sulfur. The combination of these effects would be devastating.

  17. TiC growth in C fiber/Ti alloy composites during liquid infiltration

    NASA Technical Reports Server (NTRS)

    Warrier, S. G.; Lin, R. Y.

    1993-01-01

    A cylindrical model is developed for predicting the reaction zone thickness of carbon fiber-reinforced Ti-matrix composites, and good agreement is obtained between its predicted values and experimental results. The reaction-rate constant for TiC formation is estimated to be 1.5 x 10 exp -9 sq cm/sec. The model is extended to evaluate the relationship between C-coating thicknesses on SiC fibers and processing times.

  18. Measurement of the methyl cyanide E/A ratio in TMC-1

    NASA Technical Reports Server (NTRS)

    Minh, Y. C.; Irvine, W. M.; Ohishi, M.; Ishikawa, S.; Saito, S.; Kaifu, N.

    1993-01-01

    We have observed the methyl cyanide (CH3CN) J = 2-1 K = 0 and 1 transitions toward the cyanopolyyne peak of TMC-1 and have derived an E/A (ortho/para)abundance ratio N(E)/N(A) = 0.75 +/- 0.10. The total methyl cyanide column density is N(total) = 5 x 10 exp 12/sq cm toward TMC-1, in agreement with earlier results from the J = 1-0 lines.

  19. Field Effect Transistor Behavior in Electrospun Polyaniline/Polyethylene Oxide Demonstrated

    NASA Technical Reports Server (NTRS)

    Mueller, Carl H.; Theofylaktos, Onoufrios; Robinson, Daryl C.; Miranda, Felix A.

    2004-01-01

    Novel transistors and logic devices based on nanotechnology concepts are under intense development. The potential for ultra-low-power circuitry makes nanotechnology attractive for applications such as digital electronics and sensors. For NASA applications, nanotechnology offers tremendous opportunities for increased onboard data processing, and thus autonomous decisionmaking ability, and novel sensors that detect and respond to environmental stimuli with little oversight requirements. Polyaniline/polyethylene oxide (PANi/PEO) nanofibers are of interest because they have electrical conductivities that can be changed from insulating to metallic by varying the doping levels and conformations of the polymer chain. At the NASA Glenn Research Center, we have observed field effect transistor (FET) behavior in electrospun PANi/PEO nanofibers doped with camphorsulfonic acid. The nanofibers were deposited onto Au electrodes, which had been prepatterned onto oxidized silicon substrates. The preceding scanning electron image shows the device used in the transistor measurements. Saturation channel currents are observed at surprisingly low source/drain voltages (see the following graph). The hole mobility in the depletion regime is 1.4x10(exp -4)sq cm/V sec, whereas the one-dimensional charge density (at zero gate bias) is calculated to be approximately 1 hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx.10(exp -3) S/cm). Reducing or eliminating the PEO content in the fiber is expected to enhance device parameters. Electrospinning is thus proposed as a simple method of fabricating one-dimensional polymer FET's.

  20. Thermal Vacuum Integrated System Test at B-2

    NASA Technical Reports Server (NTRS)

    Kudlac, Maureen T.; Weaver, Harold F.; Cmar, Mark D.

    2012-01-01

    The National Aeronautics and Space Administration (NASA) Glenn Research Center (GRC) Plum Brook Station (PBS) Space Propulsion Research Facility, commonly referred to as B-2, is NASA s third largest thermal vacuum facility. It is the largest designed to store and transfer large quantities of liquid hydrogen and liquid oxygen, and is perfectly suited to support developmental testing of chemical propulsion systems as well as fully integrated stages. The facility is also capable of providing thermal-vacuum simulation services to support testing of large lightweight structures, Cryogenic Fluid Management (CFM) systems, electric propulsion test programs, and other In-Space propulsion programs. A recently completed integrated system test demonstrated the refurbished thermal vacuum capabilities of the facility. The test used the modernized data acquisition and control system to monitor the facility during pump down of the vacuum chamber, operation of the liquid nitrogen heat sink (or cold wall) and the infrared lamp array. A vacuum level of 1.3x10(exp -4)Pa (1x10(exp -6)torr) was achieved. The heat sink provided a uniform temperature environment of approximately 77 K (140deg R) along the entire inner surface of the vacuum chamber. The recently rebuilt and modernized infrared lamp array produced a nominal heat flux of 1.4 kW/sq m at a chamber diameter of 6.7 m (22 ft) and along 11 m (36 ft) of the chamber s cylindrical vertical interior. With the lamp array and heat sink operating simultaneously, the thermal systems produced a heat flux pattern simulating radiation to space on one surface and solar exposure on the other surface. The data acquired matched pretest predictions and demonstrated system functionality.

  1. Measuring electrically charged particle fluxes in space using a fiber optic loop sensor

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The purpose of this program was to demonstrate the potential of a fiber optic loop sensor for the measurement of electrically charged particle fluxes in space. The key elements of the sensor are a multiple turn loop of low birefringence, single mode fiber, with a laser diode light source, and a low noise optical receiver. The optical receiver is designed to be shot noise limited, with this being the limiting sensitivity factor for the sensor. The sensing element is the fiber optic loop. Under a magnetic field from an electric current flowing along the axis of the loop, there is a non-vanishing line integral along the fiber optic loop. This causes a net birefringence producing two states of polarization whose phase difference is correlated to magnetic field strength and thus, current in the optical receiver electronic processing. The objectives in this program were to develop a prototype laser diode powered fiber optic sensor. The performance specification of a minimum detectable current density of 1 (mu)amp/sq m-(radical)Hz, should be at the shot noise limit of the detection electronics. OPTRA has successfully built and tested a 3.2 m diameter loop with 137 turns of low birefringence optical fiber and achieved a minimum detectable current density of 5.4 x 10(exp-5) amps/(radical)Hz. If laboratory space considerations were not an issue, with the length of optical fiber available to us, we would have achieved a minimum detectable current density of 4 x 10(exp -7) amps/(radical)Hz.

  2. Population of Nitrifying Bacteria and Nitrification in Ammonium Saturated Clinoptilolite

    NASA Technical Reports Server (NTRS)

    McGilloway, R. L.; Weaver, R. W.; Ming, Douglas W.; Gruener, J.

    1999-01-01

    As humans begin to spend longer periods of time in space, plants will be incorporated into life support systems. Ammonium saturated clinoptilolite is one plant growth substrate but a balance between ammonium and nitrate is needed. A laboratory study was conducted to determine effects of nitrifying bacteria on ammonium concentrations and kinetics of nitrification. Columns containing clinoptilolite substrate amended with nitrifying bacteria obtained from soil enrichment were analyzed weekly for a 90 day period. The enrichment culture initially contained 1 x 10(exp 5) ammonium oxidizing bacteria and 1 x 10(exp 2) nitrite oxidizing bacteria per gram of substrate. Populations of ammonium oxidizing bacteria increased to 1 x 10(exp 6) and nitrite oxidizing bacteria increased to 1 x 10(exp 3) per gram of substrate. The nitrification rate was approximately 0.25mg NO3(-)-N/kg.hr. Experiments were also conducted to enumerate nitrifying bacteria in a clinoptilolite substrate used to grow wheat (Triticum aestivum L.). Seventy days following the initial inoculation with an unknown number of commercial nitrifying bacteria, 1 x 10(exp 5) ammonium oxidizing bacteria per gram of substrate were present. The number of nitrite oxidizing bacteria was between 1 x 10(exp 3) to 10(exp 4) per gram of substrate as measured by the most probable number method. Nitrification rates were approximately 0.20mg NO3(-)-N/kg.hr. Clinoptilolite readily exchanged sufficient concentrations of ammonium to support nitrifying bacteria and they survived well in this medium.

  3. Evidence for a Millisecond Pulsar in 4U 1636-53 During a Superburst

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Markwardt, Craig B.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We report the discovery with the Proportional Counter Array on board the Rossi X-ray Timing Explorer of highly coherent 582 Hz pulsations during the February 22, 2001 (UT) 'superburst' from 4U 1636-53. The pulsations are detected during an 800 s interval spanning the flux maximum of the burst. Within this interval the barycentric oscillation frequency increases in a monotonic fashion from 581.89 to 581.93 Hz. The predicted orbital motion of the neutron star during this interval is consistent with such an increase as long as optical maximum corresponds roughly with superior conjunction of V801 Arae, the optical companion to the neutron star in 4U 1636-53. We show that a range of circular orbits with 90 < v(sub ns) sin i < 175 km/s and 0.336 > phi(sub 0) > 0.277 for the neutron star can provide an excellent description of the frequency and phase evolution. The brevity of the observed pulse train with respect to the 3.8 hour orbital period unfortunately does not allow more precise constraints. The average pulse profile is sinusoidal and the time averaged pulsation amplitude, as inferred from the half amplitude of the sinusoid is 1%, smaller than typical for burst oscillations observed in normal thermonuclear bursts. We do not detect any higher harmonics nor the putative subharmonic near 290 Hz. The 90% upper limits on signal amplitude at the subharmonic and first harmonic are 0.1 and 0.06%, respectively. The highly coherent pulsation, with a Q = v(sub 0)/delta-v > 4.5 x 10(exp 5) provides compelling evidence for a rapidly rotating neutron star in 4U 1636-53, and further supports the connection of burst oscillation frequencies with the spin frequencies of neutron stars. Our results provide further evidence that some millisecond pulsars are spun up via accretion in LMXBs. We also discuss the implications of our orbital velocity constraint for the masses of the components of 4U 1636-53.

  4. Improvements in contact resistivity and thermal stability of Au-contacted InP solar cells

    NASA Technical Reports Server (NTRS)

    Fatemi, Navid S.; Weizer, Victor G.

    1991-01-01

    Specific contact resistivities for as-fabricated Au contacts on n-p InP solar cells are typically in the 10(exp -3) ohm/sq cm range, but contact resistivities in the 10(exp -6) ohm/sq cm range can be obtained if the cells are heat treated at 400 C for a few minutes. This heat treatment, however, results in a dramatic drop in the open circuit voltage of the cell due to excessive dissolution of the emitter into the metallization. It was found that low values of contact resistivity can be secured without the accompanying drop in the open circuit voltage by adding Ga and In in the Au metallization. It is shown that Au contacts containing as little as 1 percent atomic Ga can suppress the reaction that takes place at the metal-InP interface during heat treatment, while exhibiting contact resistivity values in the low 10(exp -5) ohm/sq cm. Detailed explanations for the observed superior thermal stability of these contacts are presented.

  5. Measurements of NO(x) and NO(y) concentrations and fluxes over Arctic tundra

    NASA Technical Reports Server (NTRS)

    Bakwin, Peter S.; Wofsy, Steven C.; Fan, Song-Miao; Fitzjarrald, David R.

    1992-01-01

    Measurements of the atmospheric concentrations of NO, NO2, total NO(y), and O3 were made during the NASA Arctic Boundary Layer Expedition (ABLE 3A) at a remote location in a tundra bog ecosystem in southeastern Alaska during the growing season (July-August 1988). Concentrations of NO(x) and NO(y) were found to be very low compared to other remote continental sites, indicating that anthropogenic influences were small at this site during this time of year. The NO(y) emission rate from the soil were 0.13 +/- 0.05 x 10 exp 9 molecules/sq cm/s. Direct measurements of the flux of total NO(y) were made for the first time, indicating downward flux of NO(y) at all times of day, with maximum deposition of 2.5 +/- 0.9 x 10 exp 9 molecules/sq cm/s in the afternoon. Deposition of HNO3 appears to dominate the atmosphere/surface exchange of NO(y). The mean dry deposition rate of NO(y) to the tundra was 1.8 +/- 1.0 x 10 exp 9 molecules/sq cm/s.

  6. Measurements of NO(x) and NO(y) concentrations and fluxes over Arctic tundra

    SciTech Connect

    Bakwin, P.S.; Wofsy, S.C.; Fan, Songmiao; Fitzjarrald, D.R. New York State Univ., Albany )

    1992-10-01

    Measurements of the atmospheric concentrations of NO, NO[sub 2], total NO(y), and O[sub 3] were made during the NASA Arctic Boundary Layer Expedition (ABLE 3A) at a remote location in a tundra bog ecosystem in southeastern Alaska during the growing season (July-August 1988). Concentrations of NO(x) and NO(y) were found to be very low compared to other remote continental sites, indicating that anthropogenic influences were small at this site during this time of year. The NO(y) emission rate from the soil were 0.13 +/- 0.05 x 10 exp 9 molecules/sq cm/s. Direct measurements of the flux of total NO(y) were made for the first time, indicating downward flux of NO(y) at all times of day, with maximum deposition of 2.5 +/- 0.9 x 10 exp 9 molecules/sq cm/s in the afternoon. Deposition of HNO3 appears to dominate the atmosphere/surface exchange of NO(y). The mean dry deposition rate of NO(y) to the tundra was 1.8 +/- 1.0 x 10 exp 9 molecules/sq cm/s. 58 refs.

  7. High Mobility SiGe/Si Transistor Structures on Sapphire Substrates Using Ion Implantation

    NASA Technical Reports Server (NTRS)

    Alterovitz, S. A.; Mueller, C. H.; Croke, E. T.

    2003-01-01

    High mobility n-type SiGe/Si transistor structures have been fabricated on sapphire substrates by ion implanting phosphorus ions into strained 100 Angstrom thick silicon channels for the first time. The strained Si channels were sandwiched between Si(sub 0.7)Ge(sub 0.3) layers, which, in turn, were deposited on Si(sub 0.7)Ge(sub 0.3) virtual substrates and graded SiGe buffer layers. After the molecular beam epitaxy (MBE) film growth process was completed, ion thick silicon channels implantation and post-annealing were used to introduce donors. The phosphorous ions were preferentially located in the Si channel at a peak concentration of approximately 1x10(exp 18)/cu cm. Room temperature electron mobilities exceeding 750 sq cm/V-sec at carrier densities of 1x10(exp 12)/sq cm were measured. Electron concentration appears to be the key factor that determines mobility, with the highest mobility observed for electron densities in the 1 - 2x10(exp 12)/sq cm range.

  8. Self-Gravity Modeling for LISA

    NASA Technical Reports Server (NTRS)

    Merkowitz, Stephen

    2004-01-01

    The Laser Interferometer Space Antenna (LISA) mission, a space based gravitational wave detector, uses laser metrology to measure distance fluctuations between proof masses aboard three spacecraft. The total acceleration disturbance to each proof mass is required to be below 3 x 10(exp 15) m/sq square root of Hz. Self-gravity noise due to spacecraft distortion and spacecraft motion is expected to be a significant contributor to the acceleration noise budget. To minimize these effects, the gravitational field at each proof mass must be kept as small, flat, and constant as possible. It is estimated that the static field must be kept below 5 x 10(exp -10) m/sq s with a gradient below 3 x 10(exp -8)/sq s in order to meet the required noise levels. Most likely it will not be possible to directly verify by measurements that the LISA spacecraft meets these requirements; they must be verified by models. The LISA Integrated Modeling team developed a new self-gravity tool that calculates the gravitational forces and moments on the proof masses to aid in the design and verification of the LISA spacecraft. We present here an overview of&e tool and the latest self-gravity results calculated using the current baseline design of LISA. We also present results of a self-gravity analysis of the ST-7 DRS package that will fly on the LISA Pathfinder mission.

  9. Medium-resolution far-ultraviolet spectroscopy of PKS 2155-304

    NASA Technical Reports Server (NTRS)

    Appenzeller, I.; Mandel, H.; Krautter, J.; Bowyer, S.; Hurwitz, M.; Grewing, M.; Kramer, G.; Kappelmann, N.

    1995-01-01

    Using the Berkeley spectrometer of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) we observed the 87-117 nm UV spectrum of the BL Lac object PKS 2155-304 with about 0.5 A resolution. In addition to the expected interstellar lines we detected higher quantum number counterparts of the intergalactic Lyman alpha lines discovered earlier with IUE and the Hubble Space Telescope (HST) in the direction of PKS 2155-304. The Lyman discontinuities indicate for three of the redshifted clouds a combined H I column density of 2-5 x 10(exp 16)/sq cm, while the column density for another cloud appears to be well below 5 x 10(exp 15)/sq cm. No siginificant O VI absorption in the galactic halo toward PKS 2155-304 could be detected from our data. Assuming that saturation effects are negligible for these weak features, we obtain for the O VI column density toward PKS 2155-304 a 3 sigma upper limit of 2.7 x 10(exp 14)/sq cm.

  10. TID and SEE Response of an Advanced Samsung 4G NAND Flash Memory

    NASA Technical Reports Server (NTRS)

    Oldham, Timothy R.; Friendlich, M.; Howard, J. W.; Berg, M. D.; Kim, H. S.; Irwin, T. L.; LaBel, K. A.

    2007-01-01

    Initial total ionizing dose (TID) and single event heavy ion test results are presented for an unhardened commercial flash memory, fabricated with 63 nm technology. Results are that the parts survive to a TID of nearly 200 krad (SiO2), with a tractable soft error rate of about 10(exp -l2) errors/bit-day, for the Adams Ten Percent Worst Case Environment.

  11. Observation of gamma rays with a 4.8 hour periodicity from CYG X-3

    NASA Technical Reports Server (NTRS)

    Lamb, R. C.; Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.

    1976-01-01

    Energetic (E35 MeV) Gamma rays were observed from Cyg X-3 with the SAS-2 Gamma ray telescope. They are modulated at the 4.8 sup h period observed in the X-ray and infrared regions, and within the statistical error are in phase with this emission. The flux above 100 MeV has an average value of (4.4 + or - 1.1)x 10 to the -6 power/sq cm/sec. If the distance to Cyg X-3 is 10 kpcs, this flux implies a luminosity of more than 10 to the 37th power ergs/s if the radiation is isotropic and about 10 to the 36th power ergs/s if the radiation is restricted to a cone of one steradian, as it might be in a pulsar.

  12. The 4-8 micron spectrum of the infrared source W33 A

    NASA Technical Reports Server (NTRS)

    Soifer, B. T.; Puetter, R. C.; Russell, R. W.; Willner, S. P.; Harvey, P. M.; Gillett, F. C.

    1979-01-01

    The spectrum of the highly obscured infrared source W33 A from 4.5 to 8 microns is measured in order to investigate the intervening cold, dense interstellar material. Spectrophotometry at a relative spectral resolution of about 0.015 by an airborne filter-wheel infrared spectrometer reveals strong absorption features at 4.61, 5.99 and 6.78 microns. The absorption at 4.61 microns is attributed primarily to the fundamental vibration-rotation band of CO at a column density (at least 10 to the 19th/sq cm) which is 10% of the carbon inferred from silicate abundances. The strengths and line widths of the absorption agt 5.99 and 6.78 microns are interpreted as evidence of absorption in the resonance bands of carbonyl, carbon-carbon double, methyl and methylene bonds of hydrocarbons associated with interstellar dust.

  13. Pulsed high-energy gamma-radiation from Geminga (1E0630 + 178)

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Brazier, K. T. S.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

    1992-01-01

    The detection of pulsed gamma rays with energy above 50 MeV from the soft X-ray source 1E0630 + 178 is reported, confirming the identification of Geminga with this X-ray source. The period derivative (11.4 +/- 1.7) x 10 exp -15 s/s suggests that Geminga is a nearby isolated rotating neutron star with a magnetic field of 1.6 x 10 exp 12 gauss, a characteristic age of 300,000 yr, and a spin-down energy loss rate of 3.5 x 10 exp 34 erg/s.

  14. Thermal Decomposition of Some Linear Perfluoroalkanes in an Inconel Tube

    NASA Technical Reports Server (NTRS)

    Fielder, W. L.

    1961-01-01

    The products of the pyrolysis reactions of perfluoropropane, perfluoroethane, and carbon tetrafluoride in an Inconel bomb are described. The values for the energy of activation and frequency factor for the first-order pyrolysis reactions are respectively: (1) 80 kcal. per mole and 2x10(exp14) sec.(exp-1) for perfluoropropane; (2) 53 kcal. per mole and 3x10(exp7) sec.(exp-1) for perfluoroethane; and (3) 96 kcal. per mole and 4x10(exp13) sec.(exp-1) for carbon tetrafluoride.

  15. Single-Event Effect Performance of a Conductive-Bridge Memory EEPROM

    NASA Technical Reports Server (NTRS)

    Chen, Dakai; Wilcox, Edward; Berg, Melanie; Kim, Hak; Phan, Anthony; Figueiredo, Marco; Seidleck, Christina; LaBel, Kenneth

    2015-01-01

    We investigated the heavy ion SEE characteristics of an EEPROM based on CBRAM technology. SEFI is the dominant type of SEE for each operating mode (standby, read-only, write/read). We also observed single bit upsets in the CBRAM cell, during write/read tests. the SEULET threshold is between 10 and 20 MeV * sq cm/mg, with an upper fluence limit of 3 × 10(exp 6) cm(exp -2) at 10 MeV * sq cm/mg. In the stand by mode, the CBRAM array appears immune to bit upsets.

  16. The interstellar disk-halo connection in the spiral galaxy NGC 3079

    NASA Technical Reports Server (NTRS)

    Veilleux, Sylvain; Cecil, Gerald; Bland-Hawthorne, J.

    1995-01-01

    We discuss the morphology and excitation of ionized gas in the nearby Sc galaxy NGC 3079. The almost edge-on orientation is ideal for studying the vertical structure of the gaseous disk, and especially the diffuse ionized medium (DIM) found between the bright H II regions. We used the Hawaii Imaging Fabry-Perot Interferometer (HIFI) to map 150,000 H-alpha + (N II) lambda lambda 6548, 6583 emission-line profiles across the entire disk, with resolution 70 km/s at subarcsecond steps, down to a flux level of approximately 10(exp -17) ergs/s/sq cm (EM approximately equal to 4 cm(exp -6) pc). The DIM contributes approximately 30% of the total disk H-alpha emission within a radius of 10 kpc. The DIM has broader emission lines and larger (N II) H-alpha flux ratios than the adjacent H II regions. Within a radius of 5 kpc, we find that the X-shaped filaments reported in previous studies emerge from the inner (R approximately equal to 1.5 kpc) disk, and rise more than 4 kpc above the disk plane. The morphology, kinematics, and excitation of the filaments suggest that they form a biconic interface between the undisturbed disk gas, and gas entrained in the wide-angle outflow. The DIM beyond 5 kpc radius is more vertically extended than the thick ionized disk detected in our Galaxy and in a few nearby edge-on systems. After correcting for dust, the vertical profile of this DIM has an exponential scale height of about 1.1 kpc, similar to that of the H I disk. The (N II) lambda 6538/H-alpha flux ratio of the DIM increases monotonically with vertical height, reaching unity for absolute value of z greater than or approximately equal to 2.5 kpc. The flux required to keep the DIM ionized at R = 8 kpc is similar to that near the solar circle of our Galaxy. Highly dilute radiation from O stars in the galactic plane probably maintains the DIM. The total mass of the DIM is of order 10(exp 8) - 10(exp 9) solar mass, representing less than 1% of the total dynamical mass of NGC 3079

  17. Deployment loads data from a free-flight investigation of all flexible parawings having 371.612 sq meters (4000 sq feet) of wing area

    NASA Technical Reports Server (NTRS)

    Croom, D. R.

    1971-01-01

    A free-flight test program to determine the deployment characteristics of all-flexible parawings was conducted. Both single-keel and twin-keel parawings having a wing area of 4000 square feet with a five-stage reefing system were tested by use of a bomb-type instrumented test vehicle. Several twin-keel-parawing tests were also made by using an instrumented controllable sled-type test vehicle. The systems were launched from either a C-130 or a C-119 carrier airplane, and a programer parachute was used to bring the test vehicle to a proper dynamic pressure and near-vertical flight path prior to deployment of the parawing system. The free-flight deployment loads data are presented in the form of time histories of individual suspension-line loads and total loads.

  18. Fermi/GBM Observations of SGRJ0501 + 4516 Bursts

    NASA Technical Reports Server (NTRS)

    Lin, Lin; Kouveliotou, Chryssa; Baring, Matthew G.; van der Horst, Alexander J.; Guiriec, Sylvain; Woods, Peter M.; Goegues, Ersin; Kaneko, Yuki; Scargle, Jeffrey; Granot, Jonathan; Preece, Robert; von Kienlin, Andreas; Chaplin, Vandiver; Watts, Anna L.; Wijers, Ralph A. M. J.; Zhang, Shuang Nan; Bhat, Narayan; Finger, Mark H.; Gehrels. Neil; Harding, Alice; Kaper, Lex; Kaspi, Victoria; Mcenery, Julie; Meegan, Charles A.; Wilson-Hodge, Colleen

    2011-01-01

    We present our temporal and spectral analyses of 29 bursts from SGRJ0501+4516, detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray Space Telescope during the 13 days of the source activation in 2008 (August 22 to September 3). We find that the T(sub 90) durations of the bursts can be fit with a log-normal distribution with a mean value of approx. 123 ms. We also estimate for the first time event durations of Soft Gamma Repeater (SGR) bursts in photon space (i.e., using their deconvolved spectra) and find that these are very similar to the T(sub 90)s estimated in count space (following a log-normal distribution with a mean value of approx. 124 ms). We fit the time-integrated spectra for each burst and the time-resolved spectra of the five brightest bursts with several models. We find that a single power law with an exponential cutoff model fits all 29 bursts well, while 18 of the events can also be fit with two black body functions. We expand on the physical interpretation of these two models and we compare their parameters and discuss their evolution. We show that the time-integrated and time-resolved spectra reveal that E(sub peak) decreases with energy flux (and fluence) to a minimum of approx. 30 keV at F = 8.7 x 10(exp -6)erg/sq cm/s, increasing steadily afterwards. Two more sources exhibit a similar trend: SGRs J1550 - 5418 and 1806 - 20. The isotropic luminosity, L(sub iso), corresponding to these flux values is roughly similar for all sources (0.4 - l.5 x 10(exp 40) erg/s.

  19. The High-energy Continuum Emission of the Gamma-Ray Blazar PKS 0528+134

    NASA Technical Reports Server (NTRS)

    Sambruna, Rita M.; Urry, C. Megan; Maraschi, L.; Ghisellini, G.; Mukherjee, R.; Pesce, Joseph E.; Wagner, S. J.; Wehrle, A. E.; Hartman, R. C.; Lin, Y. C.; VonMintigny, C.

    1997-01-01

    We present Advanced Satellite for Cosmology and Astrophysics (ASCA) observations of the gamma-ray blazar PKS 0528 + 134, obtained at two separate epochs in 1994 August and 1995 March. These data represent the first measurement of the X-ray continuum emission of this source in the medium-hard X-ray band. Both ASCA spectra are consistent with a single power law with photon index GAMMA approx. = 1.7-1.8 and column density N(sub H) approx. = 5 x 10(exp 21)/ sq cm, higher than Galactic. The X-ray flux increased by a factor of 4 in approx. 7 months without appreciable change of the spectral shape. During the lower state of 1994 August, PKS 0528 + 134 was observed simultaneously in the optical, X-rays, and at gamma-ray energies with Energetic Gamma Ray Experiment Telescope (EGRET). The gamma-ray intensity is the faintest detected thus far in the source, with a steep spectrum (GAMMA approx. = 2.7). The extrapolation of the X-ray continuum to the gamma-ray range requires a sharp spectral break at approx. 10(exp 22) Hz. We discuss the radio through gamma-ray spectral energy distribution of PKS 0528 + 134, comparing the low state of 1994 August with the flare state of 1993 March. We show that in PKS 0528 + 134, a non-negligible contribution from the external radiation field is present and that, although synchrotron self-Compton scenarios cannot be ruled out, inverse Compton upscattering of thermal seed photons may be the dominant cooling process for the production of the high-energy continuum in this blazar.

  20. The High-Energy Continuum Emission of the Gamma-Ray Blazar PKS 0528+134

    NASA Technical Reports Server (NTRS)

    Sambruna, Rita M.; Urry, C. Megan; Maraschi, L.; Ghisellini, G.; Mukherjee, R.; Pesce, Joseph E.; Wagner, S. J.; Wehrle, A. E.; Hartman, R. C.; Lin, Y. C.

    1997-01-01

    We present Advanced Satellite for Cosmology and Astrophysics (ASCA) observations of the gamma-ray blazar PKS 0528 + 134, obtained at two separate epochs in 1994 August and 1995 March. These data represent the first measurement of the X-ray continuum emission of this source in the medium-hard X-ray band. Both ASCA spectra are consistent with a single power law with photon index GAMMA approximate 1.7-1.8 and column density N(sub H) approximately 5 x 10(exp 21) /sq cm, higher than Galactic. The X-ray flux increased by a factor of 4 in approximately 7 months without appreciable change of the spectral shape. During the lower state of 1994 August, PKS 0528 + 134 was observed simultaneously in the optical, X-rays, and at gamma-ray energies with EGRET. The gamma-ray intensity is the faintest detected thus far in the source, with a steep spectrum (GAMMA approximately 2.7). The extrapolation of the X-ray continuum to the gamma-ray range requires a sharp spectral break at approximately 10(exp 22) Hz. We discuss the radio through gamma-ray spectral energy distribution of PKS 0528 + 134, comparing the low state of 1994 August with the flare state of 1993 March. We show that in PKS 0528 + 134, a non-negligible contribution from the external radiation field is present and that, although synchrotron self-Compton scenarios cannot be ruled out, inverse Compton upscattering of thermal seed photons may be the dominant cooling process for the production of the high-energy continuum in this blazar.

  1. 1SXPS: A Deep Swift X-Ray Telescope Point Source Catalog with Light Curves and Spectra

    NASA Technical Reports Server (NTRS)

    Evans, P. A.; Osborne, J. P.; Beardmore, A. P.; Page, K. L.; Willingale, R.; Mountford, C. J.; Pagani, C.; Burrows, D. N.; Kennea, J. A.; Perri, M.; Tagliaferri, G.; Gehrels, N.

    2013-01-01

    We present the 1SXPS (Swift-XRT point source) catalog of 151,524 X-ray point sources detected by the Swift-XRT in 8 yr of operation. The catalog covers 1905 sq deg distributed approximately uniformly on the sky. We analyze the data in two ways. First we consider all observations individually, for which we have a typical sensitivity of approximately 3 × 10(exp -13) erg cm(exp -2) s(exp -1) (0.3-10 keV). Then we co-add all data covering the same location on the sky: these images have a typical sensitivity of approximately 9 × 10(exp -14) erg cm(exp -2) s(exp -1) (0.3-10 keV). Our sky coverage is nearly 2.5 times that of 3XMM-DR4, although the catalog is a factor of approximately 1.5 less sensitive. The median position error is 5.5 (90% confidence), including systematics. Our source detection method improves on that used in previous X-ray Telescope (XRT) catalogs and we report greater than 68,000 new X-ray sources. The goals and observing strategy of the Swift satellite allow us to probe source variability on multiple timescales, and we find approximately 30,000 variable objects in our catalog. For every source we give positions, fluxes, time series (in four energy bands and two hardness ratios), estimates of the spectral properties, spectra and spectral fits for the brightest sources, and variability probabilities in multiple energy bands and timescales.

  2. A performance comparison of two small rocket nozzles

    NASA Technical Reports Server (NTRS)

    Arrington, Lynn A.; Reed, Brian D.; Rivera, Angel, Jr.

    1996-01-01

    An experimental study was conducted on two small rockets (110 N thrust class) to directly compare a standard conical nozzle with a bell nozzle optimized for maximum thrust using the Rao method. In large rockets, with throat Reynolds numbers of greater than 1 x 10(exp 5), bell nozzles outperform conical nozzles. In rockets with throat Reynolds numbers below 1 x 10(exp 5), however, test results have been ambiguous. An experimental program was conducted to test two small nozzles at two different fuel film cooling percentages and three different chamber pressures. Test results showed that for the throat Reynolds number range from 2 x 10(exp 4) to 4 x 10(exp 4), the bell nozzle outperformed the conical nozzle. Thrust coefficients for the bell nozzle were approximately 4 to 12 percent higher than those obtained with the conical nozzle. As expected, testing showed that lowering the fuel film cooling increased performance for both nozzle types.

  3. The Physics of AGN, a Deep Understanding of the Quasar 3C 273

    NASA Technical Reports Server (NTRS)

    Courvoisier, T.; Bottcher, Markus

    2004-01-01

    Upon our successful AO-1 proposal no. 120023, the quasar 3C 273 has been observed with INTEGRAL in 3 epochs in January 2003. The first observation, on January 5, 2003, with a total INTEGRAL exposure of 1.2 x 10(exp 5) s, was simultaneous with RXTE and XMM- Newton observations. Two more INTEGRAL observations were carried out on January 11, 2003 (exposure: lo4 s) and January 17, 2003 (exposure: 1.1 x 10(exp 5) s). The source was detected with high significance by all INTEGRAL instruments, the OMC, JEM-X, SPI, and IBIS/ISGRI. Being one of the first INTEGRAL observations simultaneous with XMM and RXTE, our observations were also used to fix the cross calibration with those instruments. The combined spectrum resulting from the XMM-Newton, JEM-X, RXTE, SPI and ISGRI X-ray / soft gamma-ray observations is consistent with a straight power-law of photon index Gamma = (1.73 +/- 0.015) between 3 keV and at least 200 keV. A possible detection in the 200 keV - 500 keV band by SPI can not be confirmed with our observations. The normalization of the X/gamma-ray spectrum is (2.24 +/- 0.05) x 10(exp -2) photons /sq cm keV at 1 keV. The source showed a moderate amount of optical variability as observed with the OMC onboard INTEGRAL. No evidence for variability at X-rays and gamma-rays could be reported, which may have been a result of insufficient photon statistics. The X-/gamma-ray spectrum observed in our 2003 observations is consistent with previously measured and modelled broadband spectral energy distributions of 3C 273. It has been included in the U.S. lead Col's work on spectral and variability modelling of gamma-ray blazars, supporting the trend of flat-spectrum radio quasars such as 3C 273 being 7-ray dominated due to a strong contribution from Compton upscattering of external radiation by ultrarelativistic electrons in a relativistic jet. 3C 273 is a particularly convincing example for such a picture since it provides very direct evidence for a strong external radiation

  4. A Jet Break in the X-ray Light Curve of Short GRB 111020A: Implications for Energetics and Rates

    NASA Technical Reports Server (NTRS)

    Fong, W.; Berger, E.; Margutti, R.; Zauderer, B. A.; Troja, E.; Czekala, I.; Chornock, R.; Gehrels, N.; Sakamoto, T.; Fox, D. B.; Podsiadlowski, P.

    2012-01-01

    We present broadband observations of the afterglow and environment of the short GRB 111020A. An extensive X-ray light curve from Swift/XRT, XMM-Newton, and Chandra, spanning approx.100 s to 10 days after the burst, reveals a significant break at (delta)t approx. = 2 days with pre- and post-break decline rates of (alpha)X,1 approx. = -0.78 and (alpha)X,2 < or approx. 1.7, respectively. Interpreted as a jet break, we infer a collimated outflow with an opening angle of (theta)j approx. = 3deg - 8deg. The resulting beaming-corrected gamma-ray (10-1000 keV band) and blast-wave kinetic energies are (2-3) x 10(exp 48) erg and (0.3-2) x 10(exp 49) erg, respectively, with the range depending on the unknown redshift of the burst. We report a radio afterglow limit of <39 micro-Jy (3(sigma)) from Expanded Very Large Array observations that, along with our finding that v(sub c) < v(sub X), constrains the circumburst density to n(sub 0) approx.0.01 0.1/cu cm. Optical observations provide an afterglow limit of i > or approx.24.4 mag at 18 hr after the burst and reveal a potential host galaxy with i approx. = 24.3 mag. The subarcsecond localization from Chandra provides a precise offset of 0".80+/-0".11 (1(sigma))from this galaxy corresponding to an offset of 5.7 kpc for z = 0.5-1.5. We find a high excess neutral hydrogen column density of (7.5+/-2.0) x 10(exp 21)/sq cm (z = 0). Our observations demonstrate that a growing fraction of short gamma-ray bursts (GRBs) are collimated, which may lead to a true event rate of > or approx.100-1000 Gpc(sup -3)/yr, in good agreement with the NS-NS merger rate of approx. = 200-3000 Gpc(sup -3)/ yr. This consistency is promising for coincident short GRB-gravitational wave searches in the forthcoming era of Advanced LIGO/VIRGO.

  5. A new method for determining the CO to H2 conversion factor for translucent clouds

    NASA Technical Reports Server (NTRS)

    Magnani, L.; Onello, J. S.

    1995-01-01

    In this paper we describe a new technique for obtaining the conversion factor between the molecular hydrogen column density and the CO(J = 1-0) integrated antenna temperature. This factor, typically known as X(sub CO) is often to be of order a few times 10(exp 20)/sq cm/K km/s) for the molecular clouds in the Galaxy and is one of the primary means of determining the molecular cloud mass from CO observations. However, for the low-extinction interstellar clouds known as the translucent molecular clouds, estimates of X(sub CO) vary by up to a factor of 60 depending on the object and techniques employed to calibrate X(sub CO). Since the cloud mass is directly proportional to X(sub CO) uncertainties in mass estimates of translucent clouds can be more than an order of magnitude. We calibrate the H2 content in translucent clouds by using the linear relationship between the CH and H2 column densities. The CH column density is readily determined from observations of the CH ground-state hyperfine main-line transition at 3335 MHz. Using CH as a surrogate tracer for H2 and CO(J = 1-0) observations of a sample of translucent and dark molecular clouds, we find a wide variation in values for X(sub CO). For translucent clouds, X(sub CO) ranges from 0.3 to 6.8 x 10(exp 20) and for dark clouds the values range from 0.8 to 8.6. Although the average values for both types of cloud are similar to the canonical value determined for the Galactic molecular cloud ensemble (2-4 x 10(exp 20)), the scatter in individual X(sub CO) values may indicate that X(sub CO) for a given translucent cloud cannot be determined a priori and must be obtained for each cloud so that a reliable mass determination may be made.

  6. Evolution of magnetized protoplanetary disks

    NASA Technical Reports Server (NTRS)

    Reyes-Ruiz, Mauricio; Stepinski, Tomasz F.

    1995-01-01

    We investigate the global evolution of a turbulent protoplanetary disk in its viscous stage, incorporating the effects of Maxwell stress due to a large-scale magnetic field permeating disk. We assume that the viscous stress is given by an alpha model. A magnetic field is produced contemporaneously by an alpha omega dynamo mechanism and the resultant Maxwell stress assists the viscous stress in providing the means for disk evolution. The aim of this work is to compare the evolution of magnetized and nonmagnetized disks driven by turbulent viscosity of the same magnitude and thus assess the effects of a self-generated magnetic field on the structure and dynamical evolution of protoplanetary disks. Two illustrative examples corresponding to two different initial conditions are considered: a high-mass case that starts with a disk of 0.245 solar mass and angular momentum of 5.6 x 10(exp 52)g sq cm/s, and a low-mass that case starts with a disk of 0.11 solar mass and angular momentum of 1.8 x 10(exp 52)g sq cm/s. For each of these two cases the radial development of a disk is calculated numerically assuming a fiducial value of the dimensionless viscosity parameter alpha(sub ss) = 0.01, as well as alpha(sub ss) = 2 x 10(exp -3). In all cases the central star has a mass equal to 1 solar mass. The most striking feature of magnetized disk evolution is the presence of the surface density bulge located in the region of the disk where the dynamo mechanism cannot support a magnetic field. The bulge persists for a time of the order of 10(exp 5)-10(exp 6) yr. The presence and persistence of the surface density bulge may have important implications for the process of planet formation and the overall characteristics of resultant planetary systems.

  7. Evaluation Transportability Testing of the Joint Modular Intermodal Platform (JMIP) Unit #4 TP-94-01, Revision 2, June 2004, "Transportability Testing Procedures"

    DTIC Science & Technology

    2007-07-01

    5LO 1/2A PLWEI----------1 SQ T--- -- -- -- - -- LBS LB APRX CUBE ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ PG 3 -- 194C T( PRX FRONT/REA FILL (2~( REED.DSE NAVY MIC MT...TOTL_WIGH L- - - -- -- - ----------1 S (A-----------X) PAGE 4 64C T( PRX 40 1/2" 19"’- -- "-" " -112" II I I j-PLYWOOD 40-1/2" X 29" x 1/2" (1 REQOD

  8. CaLa2S4 - Ceramic window material for the 8 to 14 micron region

    NASA Astrophysics Data System (ADS)

    White, W. B.; Chess, D.; Chess, C. A.; Biggers, J. V.

    1982-10-01

    CaLa2S4 is a member of the family of ternary sulfides. It has the cubic Th3P4 structure, space group I43d, with both cations on equivalent 8-coordinated sites. Powders prepared by firing oxides and carbonates in flowing H2S can be processed by a combination of hot-pressing and hot-isostatic pressing into sulfide ceramics with good infrared transmission. The vibrational absorption edge is at 17 micron. The materials are resistant to attack by water. The microhardness of the nearly 100% dense ceramics is 600 kg/sq mm. Optical transmission of 55% (including reflection losses) at 14 micron has been achieved, but optical quality is extremely sensitive to processing conditions. Absorption and scattering are produced by residual pores, by second phase impurities on grain boundaries, by oxidation products such as sulfate and thiosulfate, and electronic defects arising from non-stoichiometry.

  9. Stimulated-emission cross section at 1064 and 1342 nm in Nd:YVO4

    NASA Technical Reports Server (NTRS)

    Tucker, A. W.; Birnbaum, M.; Fincher, C. L.; Erler, J. W.

    1977-01-01

    The stimulated-emission cross sections at 1064 and 1342 nm in Nd:YVO4 were determined by measurement of laser thresholds as a function of output mirror reflectivity. Small samples of Nd:YVO4 and Nd:YAG were end pumped at room temperature with a CW 514.5-nm argon ion laser in an almost identical geometrical arrangement which permitted comparative values to be obtained. Assuming that the pumping quantum efficiency of Nd:YVO is similar to that of Nd:YAG, the stimulated-emission cross sections obtained for the 1064- and 1342-nm transitions were respectively 12 x 10 to the -19th and 6.0 x 10 to the -19th/sq cm.

  10. Monolith catalysts for closed-cycle carbon dioxide lasers

    NASA Technical Reports Server (NTRS)

    Herz, Richard K.; Badlani, Ajay

    1991-01-01

    The objective was to explore ways of making a monolithic form of catalyst for CO2 lasers. The approach chosen was to pelletize the catalyst material, Au/MnO2 powder, and epoxy the pellets to stainless steel sheets as structural supports. The CO oxidation reaction over Au/MnO2 powder was found to be first overall, and the reaction rate constant at room temperature was 4.4 +/- 0.3 cc/(g x sec). The activation energy was 5.7 kcal/mol. The BET surface area of the pellets was found to vary from 125 to 140 sq m/g between different batches of catalyst. Pellets epoxied to stainless steel strips showed no sign of fracture or dusting when subjected to thermal tests. Pellets can be dropped onto hard surfaces with chipping of edges but no breakage of the pellets. Mechanical strength tests performed on the pellets showed that the crush strength is roughly one-fourth of the pelletizing force. The apparent activity and activation energy over the pellets were found to be less than over the powdered form of the catalyst. The lower apparent activity and activation energy of the pellets are due to the fact that the internal surface area of a pellet is not exposed to the reactant concentration present in the flowing gas as a result of intrapellet diffusion resistance. Effectiveness factors varied from 0.44, for pellets having thickness of 2 mm and attached with epoxy to a stainless steel strip. The epoxy and the stainless steel strip were found to simply block off one of the circular faces of the pellets. The epoxy did not penetrate the pellets and block the active sites. The values of the effective diffusivities were estimated to be between 2.3 x 10(exp -3) and 4.9 x 10(exp -3) sq cm/s. With measurements performed on one powder sample and one pellet configuration, reasonable accurate predictions can be made of conversions that would be obtained with other pellet thickness and configurations.

  11. Far-infrared emissivity measurements of reflective surfaces

    NASA Technical Reports Server (NTRS)

    Xu, J.; Lange, A. E.; Bock, J. J.

    1996-01-01

    An instrument developed to measure the emissivity of reflective surfaces by comparing the thermal emission of a test sample to that of a reference surface is reported. The instrument can accurately measure the emissivity of mirrors made from lightweight thermally insulating materials such as glass and metallized carbon fiber reinforced plastics. Far infrared measurements at a wavelength of 165 micrometers are reported. The instrument has an absolute accuracy of Delta epsilon = 9 x 10(exp -4) and can reproducibly measure an emissivity of as small as 2 x 10(exp -4) between flat reflective surfaces. The instrument was used to measure mirror samples for balloon-borne and spaceborne experiments. An emissivity of (6.05 +/- 1.24) x 10(exp -3) was measured for gold evaporated on glass, and (6.75 +/- 1.17) x 10(exp -3) for aluminum evaporated on glass.

  12. Numerical Modeling of Solidification in Space With MEPHISTO-4. Part 2

    NASA Technical Reports Server (NTRS)

    Simpson, James E.; Yoa, Minwu; deGroh, Henry C., III; Garimella, V. Suresh

    1998-01-01

    A pre-flight analysis of the directional solidification of BiSn with MEPHISTO-4 is presented. Simplified Bridgman growth under microgravity conditions is simulated using a two dimensional finite element model. This numerical model is a single domain, pseudo-steady state model, and includes the effects of both thermal and solutal convection. The results show that for all orientations of the applied steady state gravity vector, of magnitude 1 micro-g, the directional solidification process remains diffusion controlled. The maximum convective velocity was found to be 4.424 x 10(exp -5) cm/s for the horizontal Bridgman growth configuration. This value is an order of magnitude lower than the growth velocity. The maximum and minimum values or solute concentration in the liquid at the crystal-melt interface were 13.867 at.% and 13.722 at.%, respectively. This gives a radial segregation value of xi = 1.046% at the interface. A secondary objective of this work was to compare the results obtained to those that consider thermal convection only (no solutal convection). It was found that the convective flow patterns in simulations which included solutal convection were significantly different from those which ignored solutal convection. The level of radial segregation predicted by the current simulations is an order of magnitude lower than that found in simulations which ignore solutal convection. The final aim was to investigate the effect of g-jitter on the crystal growth process. A simulation was performed to calculate the system response to a 1 second, 100 micro-g gravity impulse acting normal to the direction of growth. This pulse is consistent with that induced by Orbiter thruster firings. The results obtained indicate that such a gravity pulse causes an increase in the level of radial solute segregation at the interface from the steady state values. The maximum value of solute concentration in the liquid was found to be 13.888 at.%, the minimum value calculated was 13

  13. An X-ray study of five supernova remnants in the Carina spiral arm

    NASA Technical Reports Server (NTRS)

    Hwang, Una; Markert, Thomas H.

    1994-01-01

    The ROSAT Position Sensitive Proportional Counter (PSPC) is used to perform an exploratory study of four fields in the Carina spiral arm containing five radio supernova remnants, only one of which has previously been studied in X-rays. We present upper limits for the detection in X-rays of G298.5 - 0.3, G298.6 - 0.0, and G299.0+0.2, and report a 4 sigma detection of G296.8-0.3. In addition, we present detailed spatial and spectral analysis of the bright X-ray remnant G296.1-0.7, which has previously been studied by both the Einstein IPC and EXOSAT LE/CMA. We detect relatively slight, but statistically significant, variations in the spectrum across the remnant via spatially resolved spectral fits and a study of the spatial variation of hardness ratios. In general, the spectrum is characteristic of a thermal plasma with kT about 0.2 keV and N(sub H) about 1.5 x 10(exp 21/sq. cm). The total X-ray emitting mass is estimated to be about 250 solar mass for an optically estimated distance of 4 kpc to the remnant. At this distance, the linear dimensions of the remnant are roughly 35 - 50 pc, implying an age on the order of 20,000 yr. Assuming that X-ray and radio brightnesses are related by SIGMA(sub R) proportional to SIGMA(exp 0.69)(sub X) and that the four radio remnants have X-ray spectral characteristics similar to G296.1-0.7, we find that the column densities to these sources must be several times 10(exp 22)/sq cm in order to explain their low X-ray count rates. This column density is considerably in excess of the X-ray fitted column density to G296.1-0.7, but is comparable to the total column densities in H I measured via the 21 cm line in the directions to all five remnants. This implies that G296.1 - 0.7 is at a significantly smaller distance than the other remnants.

  14. Time Dependent Models of Grain Formation Around Carbon Stars

    NASA Technical Reports Server (NTRS)

    Egan, M. P.; Shipman, R. F.

    1996-01-01

    Carbon-rich Asymptotic Giant Branch stars are sites of dust formation and undergo mass loss at rates ranging from 10(exp -7) to 10(exp -4) solar mass/yr. The state-of-the-art in modeling these processes is time-dependent models which simultaneously solve the grain formation and gas dynamics problem. We present results from such a model, which also includes an exact solution of the radiative transfer within the system.

  15. Heterogeneous Reaction of ClONO2(g) + NaCl(s) to Cl2(g) + NaNO3(s)

    NASA Technical Reports Server (NTRS)

    Timonen, Raimo S.; Chu, Liang T.; Leu, Ming-Taun; Keyser, Leon F.

    1994-01-01

    The heterogeneous reaction of ClON02 + NaCl yields Cl2 + NaNO3 (eq 1) was investigated over a temperature range 220-300 K in a flow-tube reactor interfaced with a differentially pumped quadrupole mass spectrometer. Partial pressures of ClON02 in the range 10(exp -8) - 10(exp -5) Torr were used. Granule sizes and surface roughness of the NaCl substrates were determined by using a scanning electron microscope, and in separate experiments, surface areas of the substrates were measured by using BET analysis of gas-adsorption isotherms. For dry NaCl substrates, both the decay rates of ClON02 and the growth rates Of C12 were used to obtain reaction probabilities, gamma(sub l) = (4.6 +/- 3.0) x 10(exp -3) at 296 K and (6.7 +/- 3.2) x 10(exp -1) at 225 K, after considering the internal surface area, The error bars represent 1 standard deviation. The Cl2 yield based on the ClONO2 reacted was measured to be 1.0 +/- 0.2. In order to mimic the conditions encountered in the lower stratosphere, the effect of water vapor pressures between 5 x 10(exp -5) and 3 x 10(exp -4) Torr on reaction 1 was also studied. With added H20, reaction probabilities, gamma = (4.1 +/- 2.1) x 10(exp -3) at 296 K and (4.7 +/- 2.9) x 10(exp -3) at 225 K, were obtained. A trace of HOCl, the reaction product from the ClON02 + H20 yield HOCl + HN03 reaction, was observed in addition to the C12 product from reaction 1. The implications of this result for the enhancement of hydrogen chloride in the stratosphere after the El Chichon volcanic eruption and for the marine troposphere are discussed.

  16. The transition region and coronal explorer (TRACE)

    NASA Technical Reports Server (NTRS)

    Title, Alan; Bruner, M.; Jurcevich, B.; Lemen, J.; Strong, K.; Tarbell, Ted; Wolfson, C. Jacob; Golub, L.; Bookbinder, J.; Fisher, R.

    1995-01-01

    The transition region and coronal explorer (TRACE) NASA small explorer mission and instrument are presented. The TRACE scientific investigation explores the relationships between fine-scale magnetic fields and the associated solar plasma structures. The instrument collects images of solar plasmas at temperatures from 10(exp 4) to 10(exp 7) K with one arcsec spatial resolution. The design specifications of the trace instrument are presented.

  17. Advanced Doppler tracking experiments

    NASA Technical Reports Server (NTRS)

    Armstrong, J. W.

    1989-01-01

    The Doppler tracking method is currently the only technique available for broadband gravitational wave searches in the approx. 10(exp -4) to 10(exp -1) Hz low frequency band. A brief review is given of the Doppler method, a discussion of the main noise sources, and a review of experience with current spacecraft and the prospects for sensitivity improvements in an advanced Doppler tracking experiment.

  18. The distribution of hydrocarbons in Neptune's upper atmosphere

    NASA Technical Reports Server (NTRS)

    Yelle, Roger V.; Herbert, Floyd; Sandel, Bill R.; Vervack, Ronald J., Jr.; Wentzel, Thomas M.

    1993-01-01

    The distribution of hydrocarbons in the upper atmosphere of Neptune is determined on the basis of data from the Voyager UVS solar occultation experiment. Densities are inferred from the transmission properties of the atmosphere measured by the UVS. The CH4 mole fraction in the lower stratosphere is between 0.0006 and 0.005. It is inferred that CH4 in Neptune's lower stratosphere is oversaturated by at least a factor of 10, and possibly by as much as a factor of 100. The density of C2H6 reaches values of 3 x 10 exp 9/cu cm near 100 microbar; a C2H6 production efficiency of 35 +15/-5 percent is derived. The eddy diffusion coefficient is approximately constant at a value of 10,000 sq cm/s at altitudes below 300 km and increases at higher altitudes as the pressure to the 0.75 power. A mole fraction of 0.001 is found to be consistent with the CH4 vapor pressure at 3.4 mbar; consequently, CH4 ice particles must reach this level to produce the inferred oversaturation.

  19. Superstable transparent conductive Cu@Cu4Ni nanowire elastomer composites against oxidation, bending, stretching, and twisting for flexible and stretchable optoelectronics.

    PubMed

    Song, Jizhong; Li, Jianhai; Xu, Jiayue; Zeng, Haibo

    2014-11-12

    Low cost and high conductivity make copper (Cu) nanowire (NW) electrodes an attractive material to construct flexible and stretchable electronic skins, displays, organic light-emitting diodes (OLEDs), solar cells, and electrochromic windows. However, the vulnerabilities that Cu NW electrodes have to oxidation, bending, and stretching still present great challenges. This work demonstrates a new Cu@Cu4Ni NW conductive elastomer composite with ultrahigh stability for the first time. Cu@Cu4Ni NWs, facilely synthesized through a one-pot method, have highly crystalline alloyed shells, clear and abrupt interfaces, lengths more than 50 μm, and smooth surfaces. These virtues provide the NW-elastomer composites with a low resistance of 62.4 ohm/sq at 80% transparency, which is even better than the commercial ITO/PET flexible electrodes. In addition, the fluctuation amplitude of resistance is within 2 ohm/sq within 30 days, meaning that at ΔR/R0 = 1, the actual lifetime is estimated to be more than 1200 days. Neither the conductivity nor the performances of OLED with elastomers as conductive circuits show evident degradation during 600 cycles of bending, stretching, and twisting tests. These high-performance and extremely stable NW elastomeric electrodes could endow great chances for transparent, flexible, stretchable, and wearable electronic and optoelectronic devices.

  20. Physics of systematic frequency variations in hydrogen masers

    NASA Technical Reports Server (NTRS)

    Mattison, Edward M.

    1990-01-01

    The frequency stability of hydrogen masers for intervals longer that 10(exp 4) seconds is limited at present by systematic processes. Researchers discuss the physics of frequency-determining mechanisms internal to the maser that are susceptible to systematic variations, and the connections between these internal mechanisms and external environmental factors. Based upon estimates of the magnitudes of systematic effects, they find that the primary internal mechanisms currently limiting long-term maser frequency stability are cavity pulling, at the level parts in 10(exp 15) per day, and wall shift variations, at the level of parts in 10(exp 16) to parts in 10(exp 15) per day. They discuss strategies for reducing systematic frequency variations.

  1. Observations of X-ray jets with the Yohkoh Soft X-ray Telescope

    NASA Technical Reports Server (NTRS)

    Shibata, Kazunari; Ishido, Yoshinori; Acton, Loren W.; Strong, Keith T.; Hirayama, Tadashi; Uchida, Yutaka; Mcallister, Alan H.; Matsumoto, Ryoji; Tsuneta, Saku; Shimizu, Toshifumi

    1992-01-01

    The features of the multiple X-ray jets in the solar corona, revealed by the time series of the Yohkoh Soft X-ray Telescope images are described. The typical size of a jet was from 5 x 10 exp 3 to 4 x 10 exp 5 km, the translational velocity was 30-300 km/s, and the corresponding kinetic energy was estimated to be from 10 exp 25 to 10 exp 28 erg. Many of the jets were found to be associated with flares in X-ray bright points, emerging flux regions, or active regions, and they sometimes occurred several times from the same X-ray feature. One of the jets associated with a flaring bright point was identified as being an H-alpha surge.

  2. Experimental Surface Pressure Data Obtained on 65 deg Delta Wing Across Reynolds Number and Mach Number Ranges. Volume 2; Small-Radius Leading Edge

    NASA Technical Reports Server (NTRS)

    Chu, Julio; Luckring, James M.

    1996-01-01

    An experimental wind tunnel test of a 65 deg. delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 84 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6) and 60 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.

  3. Rosat Observations of Nine Globular Clusters

    NASA Technical Reports Server (NTRS)

    Rappaport, S.; Dewey, D.; Levine, A.; Macri, L.

    1994-01-01

    The ROSAT HRI was used to image fields around nine Galactic globular clusters that have central densities in the range of 10(exp 4) - 10(exp 5) solar mass pc(exp -3) and that had not previously been observed with the Einstein Observatory. We detected X-ray sources associated with Pal 2 and NGC 6304 with luminosities of 1.1 x 10(exp 34) ergs/s and 1.2 x 10(exp 33) ergs/s, respectively. No X-ray emission was detected from the source in Ter 6, thus confirming its transient nature. In all, there were 23 serendipitous sources found in the nine fields; none was apparently associated with any of the other seven clusters. The results are discussed in the context of low-luminosity cluster X-ray sources, in general.

  4. Physical properties and evolutionary time scales of disks around solar-type and intermediate mass stars

    NASA Technical Reports Server (NTRS)

    Strom, Stephen E.; Edwards, Suzan

    1993-01-01

    Recent observations of circumstellar disks and their evolutionary timescales are reviewed. It is concluded that disks appear to be a natural outcome of the star-formation process. The disks surrounding young stars initially are massive, with optically thick structures comprised of gas and micron-sized grains. Disk masses are found to range from 0.01 to 0.2 solar masses for solar-type PMS stars, and from 0.01 to 6 solar masses for young, intermediate mass stars. Massive, optically thick accretion disks have accretion rates between 10 exp -8 and 10 exp -6 solar masses/yr for solar type PMS stars and between 10 exp -6 and 10 exp -4 solar masses/yr for intermediate stars. The results suggest that a significant fraction of the mass comprising the star may have passed through a circumstellar accretion disk.

  5. Line strength and self-broadening coefficient of the pure rotational S(1) quadrupole line in H2

    NASA Technical Reports Server (NTRS)

    Reuter, Dennis C.; Sirota, J. Marcos

    1994-01-01

    The absolute intensity, S(sub 1), and self-broadening coefficient, gamma(sub L), for H2 S(sub zero)(1) pure rotational line at 17.0348 micrometers (587.032 cm(exp -1)) have been measured for the first time using a tunable diode laser spectrometer with a resolution of approximately 1 x 10(exp -3) cm(exp -1). By fitting a Galatry line shape convolved with a 1 x 10(exp -3) cm(exp -1) Gaussian instrument profile to absorption profiles, for H2 pressures ranging from 0.34 to 1.30 atm, values of s(sub 1) = (7.0 +/- 0.4) x 10(exp -8) cm(exp -2) atm(exp -1) and gamma(sub L) = (1.73 +/- 0.12) x 10(exp -3) cm(exp -1) atm(exp -1) were obtained.

  6. Boeing F4B-4

    NASA Technical Reports Server (NTRS)

    1932-01-01

    The Boeing F4B-4 was seen to differ from earlier F4Bs in having a vertical fin with slightly more area. The Boeing model 235 was not fitted with a NACA cowling, but rather the less efficient 'Townend' ring around the Pratt & Whitney Wasp radials cylinders. This aircraft was much used by both the Navy and the Army Air Corps in the late 1920's and early 1930's. The Army variation was known as the P-12E. The engine cowling was a British development known as the 'Townend' ring. It differed from the NACA cowling and was less effective in reducing the drag.

  7. X-ray Properties of an Unbiased Hard X-ray Detected Sample of AGN

    NASA Technical Reports Server (NTRS)

    Winter, Lisa M.; Mushotzky, Richard F.; Tueller, Jack; Markwardt, Craig

    2007-01-01

    The SWIFT gamma ray observatory's Burst Alert Telescope (BAT) has detected a sample of active galactic nuclei (AGN) based solely on their hard X-ray flux (14-195keV). In this paper, we present for the first time XMM-Newton X-ray spectra for 22 BAT AGXs with no previously analyzed X-ray spectra. If our sources are a representative sample of the BAT AGN, as we claim, our results present for the first time global X-ray properties of an unbiased towards absorption (n(sub H) < 3 x 10(exp 25)/sq cm), local (< z >= 0.03), AGN sample. We find 9/22 low absorption (n(sub H) < 10(exp 23)/sq cm), simple power law model sources, where 4 of these sources have a statistically significant soft component. Among these sources, we find the presence of a warm absorber statistically significant for only one Seyfert 1 source, contrasting with the ASCA results of Reynolds (1997) and George et al. (1998), who find signatures of warm absorption in half or more of their Seyfert 1 samples at similar redshifts. Additionally, the remaining sources (13122) have more complex spectra, well-fit by an absorbed power law at E > 2.0 keV. Five of the complex sources (NGC 612, ESO 362-G018, MRK 417, ESO 506-G027, and NGC 6860) are classified as Compton-thick candidates. Further, we find four more sources (SWIFT J0641.3+3257, SWIFT J0911.2+4533, SWIFT J1200.8+0650, and NGC 4992) with properties consistent with the hidden/buried AGN reported by Ueda et al. (2007). Finally, we include a comparison of the XMM EPIC spectra with available SWIFT X-ray Telescope (XRT) observations. From these comparisons, we find 6/16 sources with varying column densities, 6/16 sources with varying power law indices, and 13/16 sources with varying fluxes, over periods of hours to months. Flux and power law index are correlated for objects where both parameters vary.

  8. Constraints on Saturn's Tropospheric General Circulation from Cassini ISS Images

    NASA Technical Reports Server (NTRS)

    DelGenio, Anthony D.; Barbara, John M.

    2013-01-01

    An automated cloud tracking algorithm is applied to Cassini Imaging Science Subsystem high-resolution apoapsis images of Saturn from 2005 and 2007 and moderate resolution images from 2011 and 2012 to define the near-global distribution of zonal winds and eddy momentum fluxes at the middle troposphere cloud level and in the upper troposphere haze. Improvements in the tracking algorithm combined with the greater feature contrast in the northern hemisphere during the approach to spring equinox allow for better rejection of erroneous wind vectors, a more objective assessment at any latitude of the quality of the mean zonal wind, and a population of winds comparable in size to that available for the much higher contrast atmosphere of Jupiter. Zonal winds at cloud level changed little between 2005 and 2007 at all latitudes sampled. Upper troposphere zonal winds derived from methane band images are approx. 10 m/s weaker than cloud level winds in the cores of eastward jets and approx. 5 m/s stronger on either side of the jet core, i.e., eastward jets appear to broaden with increasing altitude. In westward jet regions winds are approximately the same at both altitudes. Lateral eddy momentum fluxes are directed into eastward jet cores, including the strong equatorial jet, and away from westward jet cores and weaken with increasing altitude on the flanks of the eastward jets, consistent with the upward broadening of these jets. The conversion rate of eddy to mean zonal kinetic energy at the visible cloud level is larger in eastward jet regions (5.2x10(exp -5) sq m/s) and smaller in westward jet regions (1.6x10(exp -5) sqm/s) than the global mean value (4.1x10(ep -5) sq m/s). Overall the results are consistent with theories that suggest that the jets and the overturning meridional circulation at cloud level on Saturn are maintained at least in part by eddies due to instabilities of the large-scale flow near and/or below the cloud level.

  9. Strange meson spectroscopy in K(omega) and K(phi) at 11 GeV/c and Cherenkov ring imaging at SLD

    NASA Astrophysics Data System (ADS)

    Kwon, Youngjoon

    1993-01-01

    This thesis consists of two independent parts: development of a Cherenkov Ring Imaging Detector (CRID) system; and analysis of high-statistics data of strange meson reactions from the LASS spectrometer. The CRID system is devoted to charged particle identification in the SLAC Large Detector (SLD) to study e(+)e(-) collisions at radical s = m(sub Z(exp 0)). By measuring the angles of emission of the Cherenkov photons inside liquid and gaseous radiators, pi/K/p separation will be achieved up to approximately 30 GeV/c. The signals from CRID are read in three coordinates, one of which is measured by charge-division technique. To obtain an approximately 1% spatial resolution in the charge-division, low-noise CRID preamplifier prototypes were developed and tested resulting in less than 1000 electrons noise for an average photoelectron signal with 2(10)(exp 5) gain. To help ensure the long-term stability of CRID operation at high efficiency, a comprehensive monitoring and control system was developed. Results from the partial wave analysis of strange meson final states in the reactions K(-)p yields K(-)(omega)p and K(-)p yields (K-bar)(exp 0)(phi)n are presented. The analyses are based on data from a 4.1 event/nb exposure of the LASS spectrometer in K(-)p interactions at 11 GeV/c. The data sample of K(-)(omega)p final state contains approximately 10(exp 5) events. From the partial wave analysis, resonance structures of J(exp P) = 2(-), 3(-), and 2(+) amplitudes are observed in the K(omega) system. The analysis of 2(-) amplitudes provides an evidence for two strange meson states in the mass region around 1.75 GeV/sq c. The appropriate branching fractions are calculated and compared with the SU(3) predictions. The partial wave analysis of (K-bar)(exp 0)(phi) system favors J(exp P) = 1(-) and 2(+) states in the 1.9-2.0 GeV/sq c region.

  10. Development of lightweight graphite/polyimide sandwich panels, phases 3, 4 and 5

    NASA Technical Reports Server (NTRS)

    Merlette, J. B.

    1972-01-01

    Work performed in the last three phases of the program included: (1) face sheet processing; (2) honeycomb core manufacture; (3) face sheet-to-core bonding development; and (4) sandwich panel fabrication and testing. Resin cure studies were a major portion of this effort since processing problems traced to the polyimide matrix resin had to be resolved before quality core and face sheets could be fabricated. Honeycomb core fabrication and testing were conducted by Hexcel Corporation. A total of four graphite/polyimide resin composite cores were fabricated, tested, and reported. Two sandwich panels weighing .48 and .58 lb/sq ft, respectively were designed and fabricated which meet the support structure loads for the shuttle orbiter thermal protection system.

  11. Detection of a new circumstellar carbon chain molecule, C4Si

    NASA Technical Reports Server (NTRS)

    Ohishi, Masatoshi; Kaifu, Norio; Kawaguchi, Kentarou; Murakami, Akinori; Saito, Shuji

    1989-01-01

    A new interstellar carbon chain molecule, C4Si, has been detected in the envelope of the evolved star IRC + 10216. This molecule is the carrier of six unidentified lines which had been detected during the molecular line survey at Nobeyama Radio Observatory. The identification was made through astronomical detections followed by quantum chemical calculations and laboratory spectroscopic experiments. The rotational constant and the centrifugal distortion constant were B(0) = 1533.77206(146) MHz and D(0) = 0.00005827(35) MHz, respectively, where the numbers in parentheses represent one standard deviation in units of the last significant digits. The rotation temperature and the column density were 15 + or - 2 K and (7 + or - 1) x 10 to the 12th/sq cm, respectively, assuming a source size of 25 arcsec.

  12. The fate of atmospheric phosgene and the stratospheric chlorine loadings of its parent compounds: CCl4, C2Cl4, C2HCL3, CH3CCl3, and CHCl3

    NASA Technical Reports Server (NTRS)

    Kindler, T. P.; Chameides, W. L.; Wine, P. H.; Cunnold, D. M.; Alyea, F. N.; Franklin, J. A.

    1995-01-01

    of reaction of phosgene with sulfate aerosols. However, on the basis of the observed vertical distribution of COCl2, we estimate that the reaction of COCl2 with sulfate aerosol most likely has a gamma less than 5 x 10(exp -5) and, as a result, has a negligible impact on the stratospheric chlorine loadings of the phosgene parent compounds.

  13. A Hot-electron Direct Detector for Radioastronomy

    NASA Technical Reports Server (NTRS)

    Karasik, Boris S.; McGrath, William R.; LeDuc, Henry G.; Gershenson, Michael E.

    1999-01-01

    A hot-electron transition-edge superconducting bolometer with adjustable thermal relaxation speed is proposed. The bolometer contacts are made from a superconductor with high critical temperature which blocks the thermal diffusion of hot carriers into the contacts. Thus electron-phonon interaction is the only mechanism for heat removal. The speed of thermal relaxation for hot electrons in a nanometer-size superconducting bolometer with T(sub c) = 100-300 mK is controlled by the elastic electron mean free path l. The relaxation rate behaves as T(sup 4)l at subkelvin temperatures and can be reduced by a factor of 10-100 by decreasing 1. Then an antenna- or wave guide-coupled bolometer with a time constant approx. = 10(exp -3) to 10(exp -4) s will exhibit photon-noise limited performance at millimeter and submillimeter wavelengths. The bolometer will have a figure-of-merit NEPtau = 10(exp -22) - 10(exp -21) W/Hz at 100 mK which is 10(exp 3) to 10(exp 4) times better (ie: smaller) than that of a state-of-the-art bolometer. A tremendous increase in speed and sensitivity will have a significant impact for observational mapping applications.

  14. 4-Aminopyridine

    Integrated Risk Information System (IRIS)

    4 - Aminopyridine ; CASRN 504 - 24 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  15. 4-Methylphenol

    Integrated Risk Information System (IRIS)

    4 - Methylphenol ; CASRN 106 - 44 - 5 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  16. Chromium Diffusion Doping on ZnSe Crystals

    NASA Technical Reports Server (NTRS)

    Journigan, Troy D.; Chen, K.-T.; Chen, H.; Burger, A.; Schaffers, K.; Page, R. H.; Payne, S. A.

    1997-01-01

    Chromium doped zinc selenide crystal have recently been demonstrated to be a promising material for near-IR room temperature tunable lasers which have an emission range of 2-3 micrometers. In this study a new diffusion doping process has been developed for incorporation of Cr(+2) ion into ZnSe wafers. This process has been successfully performed under isothermal conditions, at temperatures above 800 C. Concentrations in excess of 10(exp 19) Cr(+2) ions/cu cm, an order of magnitude larger than previously reported in melt grown ZnSe material, have been obtained by diffusion doping, as estimated from optical absorption measurements. The diffusivity was estimated to be about 10(exp -8) sq cm/sec using a thin film diffusion model. Resistivity was derived from current-voltage measurements and in the range of 10(exp 13) and 10(exp 16) omega-cm. The emission spectra and temperature dependent lifetime data will also be presented and discussed.

  17. Ammonia Observations of NGC 6334 I(N)

    NASA Technical Reports Server (NTRS)

    Kuiper, T. B. H.; Peters, W. L., III; Foster, J. R.; Gardner, F. F.; Whiteoak, J. B.

    1995-01-01

    Coincident with the far-infrared source NGC 6334 I(N) and water maser source E is a massive dense cloud which has the most intense ammonia (1, 1) emission of any known interstellar cloud. We have mapped the (3, 3) emission and find the cloud is extended 0.8 pc in the direction parallel to the Galactic plane, and 0.5 pc perpendicular to it. It has a velocity gradient of 1 km/s.pc perpendicular to the Galactic plane. The gas kinetic temperature is about 30 K and the density is greater than 10(exp 6)/cc. The mass of the cloud is about 3000 solar mass, 3 times greater than previously estimated. The para-ammonia column density is 6 - 8 x 10(exp 15)/sq cm. An ammonia abundance of 0.5 - 1.5 x 10(exp -8) is inferred, where the larger number assumes an early time ortho/para ratio. This suggests either a cloud age of less than approximately 10(exp 6) yr, or substantial depletion of ammonia.

  18. Formation, early evolution, and gravitational stability of protoplanetary disks

    NASA Technical Reports Server (NTRS)

    Nakamoto, Taishi; Nakagawa, Yoshitsugo

    1994-01-01

    The formation, viscous evolution, and gravitational stability of protoplanetary disks are investigated. The formation process is parameterized by the angular velocity of the molecular cloud core omega, while the viscous evolution is parameterized by the viscosity parameter alpha in the disk; in this study we consider a range of (0.4-6) x 10(exp -14)/s for omega and from 10(exp -5) to 10(exp -1) for alpha. The axisymmetric gravitational stabilities of the disks are checked using Toomre's criterion. The resulting disk surface temperature distribution, (d log T(sub s)/d log R) approximately = -0.6 (R is the cylindrical radius), can be attributed to two heating sources: the viscous heating dominant in the inner disk region, and the accretion shock heating dominant in the outer disk region. This surface temperature distribution matches that observed in many disks around young stellar objects. During the infall stage, disks with alpha less than 10(exp -1.5) become gravitationally unstable independent of omega. The gravitational instabilities occur at radii ranging from 5 to 40 AU. The ratio of the disk mass to the central star mass ranges from 0.2 to 0.5 at the times of instability, about 4 x 10(exp -5) x (omega/10(exp -14)/s)(exp -0.67) yr. Most disks with low alpha and high omega become gravitationally unstable during their formation phase.

  19. Field-emitter arrays for vacuum microelectronics

    NASA Technical Reports Server (NTRS)

    Spindt, C. A.; Holland, C. E.; Rosengreen, A.; Brodie, Ivor

    1991-01-01

    An ongoing program on microfabricated field-emitter arrays has produced a gated field-emitter tip structure with submicrometer dimensions and techniques for fabricating emitter arrays with tip packaging densities of up to 1.5 x 10 exp 7 tips/sq cm. Arrays have been fabricated over areas varying from a few micrometers up to 13 cm in diameter. Very small overall emitter size, materials selection, and rigorous emitter-tip processing procedures have contributed to reducing the potential required for field emission to tens of volts. Emission current densities of up to 100 A/sq cm have been achieved with small arrays of tips, and 100-mA total emission is commonly produced with arrays 1 mm in diameter containing 10,000 tips. Transconductances of 5.0 micro-S per tip have been demonstrated, indicating that 50 S/sq cm should be achievable with tip densities of 10 exp 7 tips/sq cm. Details of the cathode arrays and a variety of performance characteristics are discussed.

  20. Energy of Cohesion, Compressibility, and the Potential Energy Functions of the Graphite System

    NASA Technical Reports Server (NTRS)

    Girifalco, L. A.; Lad, R. A.

    1956-01-01

    The lattice summations of the potential energy of importance in the graphite system have been computed by direct summation assuming a Lennard-Jones 6-12 potential between carbon atoms. From these summations, potential energy curves were constructed for interactions between a carbon atom and a graphite monolayer, between a carbon atom and a graphite surface, between a graphite monolayer and a semi-infinite graphite crystal and between two graphite semi-infinite crystals. Using these curves, the equilibrium distance between two isolated physically interacting carbon atoms was found to be 2.70 a, where a is the carbon-carbon distance in a graphite sheet. The distance between a surface plane and the rest of the crystal was found to be 1.7% greater than the interlayer spacing. Theoretical values of the energy of cohesion and the compressibility were calculated from the potential curve for the interaction between two semi-infinite crystals. They were (delta)E(sub c) = -330 ergs/sq cm and beta =3.18x10(exp -12)sq cm/dyne, respectively. These compared favorably with the experimental values of (delta)E(sub c) = -260 ergs/sq cm and beta = 2.97 X 10(exp -2) sq cm/dyne.

  1. Building and mining web-based questionnaires and surveys with SySQ.

    PubMed

    Sarica, Alessia; Guzzi, Pietro Hiram; Cannataro, Mario

    2013-09-01

    A questionnaire is a method for collecting data that can come from many sources such as observations, telephone interviews or documentary sources. Whatever the source of data is, the questionnaire provides a framework of questions that facilitate researcher's work. A manual approach for collecting data using questionnaire presents some limitations and introduces several sources of errors. A second issue regards the statistical and data mining of data that often is conducted using different tools than the questionnaire system, which may introduce errors in the analysis pipeline. For instance, common methods applied to data set concern the normality test, the association and correlation discovery, linear regression, classification and clustering. Usually this analysis is performed using external tools, often not free, such as SPSS, SAS, STATA, Weka, or Clementine.We present a web-based software system, to automatize the analysis pipeline and to support researchers involved in the collection of questionnaire data, such as in epidemiology, aiming to reduce the errors listed above and including some basic functions to conduct statistical analysis on collected data. Our system allows researchers to create questionnaires, adding sections and structured questions. It provides a preview of the questionnaire, the exportation of saved data into statistical software compatible formats, or it permits to analyze them directly applying statistical methods and common data mining techniques from the main interface.

  2. Driving CZTS to the SQ Limit: Solving the Open Circuit Voltage Problem

    SciTech Connect

    Haight, Richard A.; McCandless, Brian E.; Kummel, Andrew C.; Gordon, Roy G.

    2016-12-15

    A key objective of this 3 year research effort was to reduce the open circuit voltage (Voc) deficit, defined as the difference between the absorber band gap and the measured Voc to below 475mV from values at the beginning of this work of 630-730mV. To achieve this reduction, along with the attendant goals of higher Voc and efficiency, detailed studies into the fundamental understanding of existing limitations were undertaken.

  3. Multiple-dose pharmacokinetics of the monobactam azthreonam (SQ 26,776) in healthy subjects.

    PubMed Central

    Swabb, E A; Sugerman, A A; McKinstry, D N

    1983-01-01

    Azthreonam, a monocyclic beta-lactam highly active against aerobic gram-negative bacteria in vitro, was administered to four groups of nine healthy male volunteers in the following four regimens: 500 mg intravenously (i.v.) over 2 min every 8 h, 1,000 mg i.v. over 2 min every 8 h, 500 mg intramuscularly (i.m.) every 8 h, and 1,000 mg i.m. every 8 h for 7 days. Serial samples of serum and urine were assayed by microbiological methods, and urine samples collected during the high-dose i.m. regimen were assayed by a high-pressure liquid chromatographic procedure. Mean peak serum levels were 39 and 99 micrograms/ml after the initial i.v. doses and 18 and 39 micrograms/ml after the initial i.m. doses. There was no evidence of drug accumulation. Mean serum trough levels were 1.0 and 2.5 micrograms/ml during the two i.v. regimens and 1.8 and 3.8 micrograms/ml during the two i.m. regimens. The mean difference among Cmax, area under the curve from 0 to 8 h, and urinary recovery at 0 to 8 h on days 1 and 8 was less than 13% for each regimen. From the i.v. study, the mean steady-state volume of distribution was 0.21 liter/kg, the terminal half-life was 1.6 h, serum clearance was 1.7 ml min-1 kg-1, urinary recovery was 60%, and serum protein binding was 56%. An average of about 6% of a 1,000-mg i.m. dose was excreted in the 8-h urine collection on day 8 as the open beta-lactam ring hydrolysis product of azthreonam. The concentrations of azthreonam in serum were within the range required to inhibit growth of susceptible organisms in vitro. PMID:6681947

  4. Design, Development & Flight Testing Of The U.S. Army 4200 sq ft Parafoil Recovery System

    NASA Technical Reports Server (NTRS)

    Bennett, Thomas W.; Fox, Roy

    2007-01-01

    The purpose of this paper is to describe the design, development and flight testing of the U.S. Army 4200 ft(sup 2) parafoil recovery system built under NASA Contract NAS9-00076. The 4200 ft(sup 2) parafoil described herein was a potential candidate to fulfill the U.S. Army requirement for a 10,000 lb useable payload precision guided recovery system. Design heritage as well as specific features, like lower surface inlets, confluence fitting, upper surface energy modulator design, deployment bag design and 60 ft diameter Ringslot drogue will be discussed. Initial flight test results, ground testing of various components to verify design margin and configuration changes will also be discussed. The 4200 ft(sup 2) parafoil recovery system completed three flight tests during 2003 at payload weights of over 15,000 lbs.

  5. Longitudinal difference in the Sq profiles in the South American region

    NASA Astrophysics Data System (ADS)

    Kane, R. P.

    1986-07-01

    The average daily variation profiles of the H component at Huancayo on the west coast and Eusebio, Fortaleza, on the east coast in the dip equator region and La Quiaca near the west coast and Vassouras near the east coast in the southern low latitude region of the South American continent indicate that the profiles are broader for the east coast. Thus, distortions in the overhead current systems while passing from one coast to the other are indicated.

  6. ROSAT observations of NGC 2146: Evidence for a starburst-driven superwind

    NASA Technical Reports Server (NTRS)

    Armus, L.; Heckman, T. M.; Weaver, K. A.; Lehnert, M. D.

    1995-01-01

    We have imaged the edge-on starburst galaxy NGC 2146 with the Position Sensitive Proportional Counter (PSPC) and the High Resolution Imager (HRI) on board ROSAT and have compared these data to optical images and long-slit spectra. NGC 2146 possesses a very large X-ray nebula with a half-light radius of 1 min (4 kpc) and a maximum diameter of approximately 4 min, or 17 kpc. The X-ray emission is resolved by the PSPC and preferentially oriented along the minor axis, with a total flux of 1.1 x 10(exp -12) ergs/sq cm/s over 0.2 - 2.4 keV and a luminosity of approximately 3 x 10(exp 40) ergs/s. The inner X-ray nebula is resolved by the HRI into at least four bright knots together with strong diffuse emission responsible for at least 50% of the flux within a radius of 0.5 min (approximately 2 kpc). The brightest knot has a luminosity of (2 - 3) x 10(exp 39) ergs/s. The X-ray nebula has a spatial extent much larger than the starburst ridge seen at centimeter wavelengths by Kronberg & Biermann (1981) and is oriented in a `X-like' pattern along the galaxy minor axis at a position angle of approximately 30 degrees. This minor-axis X-ray emission is associated with a region of H alpha and dust filaments seen in optical images. Optical spectra show that the emission-line gas along the minor axis is characterized by relatively broad lines (approximately 250 km/s full width half-maximum (FWHM)) and by `shocklike' emission-line flux ratios. Together with the blue-asymmetric nuclear emission-line and NaD interstellar absorption-line profiles, these optical data strongly suggest the presence of a starburst-driven superwind. The X-ray spectrum extracted from the central 5 min contains a strong Fe L emission-line complex at 0.6 - 1.0 keV and a hard excess above 1.0 keV. The spectrum is best described with a two-component model, containing a soft (kT approximately 400 - 500 eV) Raymond-Smith thermal plasma together with either a Gamma = 1.7 power-law or a kT greater than 2.2 ke

  7. Fast and Accurate Hybrid Stream PCRTMSOLAR Radiative Transfer Model for Reflected Solar Spectrum Simulation in the Cloudy Atmosphere

    NASA Technical Reports Server (NTRS)

    Yang, Qiguang; Liu, Xu; Wu, Wan; Kizer, Susan; Baize, Rosemary R.

    2016-01-01

    A hybrid stream PCRTM-SOLAR model has been proposed for fast and accurate radiative transfer simulation. It calculates the reflected solar (RS) radiances with a fast coarse way and then, with the help of a pre-saved matrix, transforms the results to obtain the desired high accurate RS spectrum. The methodology has been demonstrated with the hybrid stream discrete ordinate (HSDO) radiative transfer (RT) model. The HSDO method calculates the monochromatic radiances using a 4-stream discrete ordinate method, where only a small number of monochromatic radiances are simulated with both 4-stream and a larger N-stream (N = 16) discrete ordinate RT algorithm. The accuracy of the obtained channel radiance is comparable to the result from N-stream moderate resolution atmospheric transmission version 5 (MODTRAN5). The root-mean-square errors are usually less than 5x10(exp -4) mW/sq cm/sr/cm. The computational speed is three to four-orders of magnitude faster than the medium speed correlated-k option MODTRAN5. This method is very efficient to simulate thousands of RS spectra under multi-layer clouds/aerosols and solar radiation conditions for climate change study and numerical weather prediction applications.

  8. Four micron high-resolution spectra of Jupiter in the North Equatorial Belt: H3(+) emissions and the C-12/C-13 ratio

    NASA Technical Reports Server (NTRS)

    Marten, A.; De Bergh, C.; Owen, T.; Gautier, D.; Maillard, J. P.; Drossart, P.; Lutz, B. L.; Orton, G. S.

    1994-01-01

    Spectra of the North Equatorial Belt of Jupiter were obtained in March 1992 at an unapodized resolution of 0.1/cm between 2450 and 2600/cm with the Fourier Transform Spectrometer at the 3.6 m Canada-France-Hawaii Telescope (CFHT) on Mauna Kea. Several emissions from the nu(sub 2) band of H3(+) were detected. The excitation temperature derived from the relative intensities of these emissions averaged over a wide range of longitudes is 800 +/- 100 K, and the H3(+) column density is 1.56(sup +1.0)(sub -0.5) x 10(exp 11)/sq. cm. In addition, several strong absorption features due to (13)CH4 were observed. A comparison between (12)CH4 and (13)CH4 absorptions allowed us to obtain a new measurement of the C-12/C-13 ratio. We found that this ratio, estimated for the first time in this spectral range, is 89 (+/- 25), in agreement with the terrestrial value.

  9. Metallic copper in ordinary chondrites

    NASA Technical Reports Server (NTRS)

    Rubin, Alan E.

    1994-01-01

    Metallic Cu of moderately high purity (approximately 985 mg/g Cu, approximately 15 mg/g Ni) occurs in at least 66% of ordinary chondrites (OC) as heterogeneously distributed, small (typically less than or equal to 20 micrometers) rounded to irregular grains. The mean modal abundance of metallic Cu in H, L and LL chondrites is low: 1.0 to 1.4 x 10(exp -4) vol%, corresponding to only 4 - 5 % of the total Cu in OC whole rocks. In more than 75% of the metallic-Cu-bearing OC, at least some metallic Cu occurs at metallic-Fe-Ni-troilite grain boundaries. In some cases it also occurs within troilite, within metallic Fe-Ni, or at the boundaries these phases form with silicates or chromite. Ordinary chondrites that contain a relatively large number of occurrences of metallic Cu/sq mm have a tendency to have experienced moderately high degrees of shock. Shock processes can cause local melting and transportation of metallic Fe-Ni and troilte; because metallic Cu is mainly associated with these phases, it also gets redistributed during shock events. In the most common petrographic assemblage containing metallic Cu, the Cu is adjacent to small irregular troilite grains surrounded by taenite plus tetrataenite; this assemblage resembles fizzed troilite and may have formed by localized shock melting or remelting of a metal-troilite assemblage.

  10. 17 CFR 4.2-4.4 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false 4.2-4.4 Section 4.2-4.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION COMMODITY POOL OPERATORS AND COMMODITY TRADING ADVISORS General Provisions, Definitions and Exemptions §§ 4.2-4.4...

  11. 17 CFR 4.2-4.4 - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 1 2011-04-01 2011-04-01 false 4.2-4.4 Section 4.2-4.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION COMMODITY POOL OPERATORS AND COMMODITY TRADING ADVISORS General Provisions, Definitions and Exemptions §§ 4.2-4.4...

  12. 17 CFR 4.2-4.4 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 1 2012-04-01 2012-04-01 false 4.2-4.4 Section 4.2-4.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION COMMODITY POOL OPERATORS AND COMMODITY TRADING ADVISORS General Provisions, Definitions and Exemptions §§ 4.2-4.4...

  13. 17 CFR 4.2-4.4 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 1 2014-04-01 2014-04-01 false 4.2-4.4 Section 4.2-4.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION COMMODITY POOL OPERATORS AND COMMODITY TRADING ADVISORS General Provisions, Definitions and Exemptions §§ 4.2-4.4...

  14. 17 CFR 4.2-4.4 - [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 1 2013-04-01 2013-04-01 false 4.2-4.4 Section 4.2-4.4 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION COMMODITY POOL OPERATORS AND COMMODITY TRADING ADVISORS General Provisions, Definitions and Exemptions §§ 4.2-4.4...

  15. Stability Characteristics of Two Missiles of Fineness Ratios 12 and 18 with Six Rectangular Fins of Very Low Aspect Ratio Over a Mach Number Range of 1.4 to 3.2

    NASA Technical Reports Server (NTRS)

    Henning, Allen B.

    1959-01-01

    Two rocket-propelled missiles have been test flown by the Langley Pilotless Aircraft Research Division in order to study the stability characteristics of a body with six rectangular fins of very low aspect ratio. The fins, which had exposed aspect ratios of approximately o.o4 and 0.02 per fin, were mounted on bodies of fineness ratios of 12 and 18, respectively. Each body had a nose with a fineness ratio of 3.5 and a cylindrical afterbody. The body and the fin chord of the model having a fineness ratio of 12 were extended the length of 6 body diameters to produce the model with a fineness ratio of 18. The missiles were disturbed in flight by pulse rockets in order to obtain the stability data. The tests were performed over a Mach number range of 1.4 to 3.2 and a Reynolds number range of 2 x 10(exp 6) to 21 x l0(exp 6). The results of these tests indicate that these configurations with the long rectangular fins of very low aspect ratio showed little induced roll" with the missile of highest fineness ratio and longest fin chord exhibiting the least amount. Extending the body and fin chord of the shorter missile six body diameters and thereby increasing the fin area approximately 115 percent increased the lift-curve slope based on body cross-sectional area approximately 40 to 55 percent, increased the dynamic stability by a substantial amount, and increased the drag from 14 to 33 percent throughout the comparable Mach number range. The center-of-pressure location of both missiles remained constant over the Mach number range.

  16. Impact winter and the Cretaceous/Tertiary extinctions: Results of a Chicxulub asteroid impact model

    NASA Technical Reports Server (NTRS)

    Pope, Kevin O.; Baines, Kevin H.; Ocampo, Adriana C.; Ivanov, Boris A.

    1994-01-01

    The Chicxulub impact crater in Mexico is the site of the impact purported to have caused mass extinctions at the Cretaceous/Tertiary (K/T) boundary. 2-D hydrocode modeling of the impact, coupled with studies of the impact site geology, indiate that between 0.4 and 7.0 x 10(exp 17) g of sulfur were vaporized by the impact into anhydrite target rocks. A small portion of the sulfur was released as SO3 or SO4, which converted rapidly into H2SO4 aerosol and fell as acid rain. A radiative transfer model, coupled with a model of coagulation indicates that the aerosol prolonged the initial blackout period caused by impact dust only if the aerosol contained impurities. A larger portion of sulfur was released as SO2, which converted to aerosol slowly, due to the rate-limiting oxidation of SO2. Our radiative transfer calculations, combined with rates of acid production, coagulation, and diffusion indicate that solar transmission was reduced to 10-20% of normal for a period of 8-13 yr. This reduction produced a climate forcing (cooling) of -300 W/sq.m, which far exceeded the +8 W/sq.m greenhouse warming, caused by the CO2 released through the vaporization of carbonates, and therefore produced a decade of freezing and near-freezing temperatures. Several decades of moderate warming followed the decade of severe cooling due to the long residence time of CO2. The prolonged impact winter may have been a major cause of the K/T extinctions.

  17. Implanted contacts for diamond semiconductor devices

    NASA Astrophysics Data System (ADS)

    Tan, Soo-Hee; Beetz, C. P., Jr.

    1992-01-01

    The key to future diamond semiconductor development are ohmic and Schottky contacts that are stable at high temperatures. Wide bandgap materials, such as diamond (5.5 eV), pose special problems and demand ingenious solutions. Prior to our work, recent research into stable ohmic and Schottky contacts had been primarily limited to e-beam evaporation of carbide forming metals such as Ti, Ta, and Mo. These approaches have been relatively successful at decreasing the specific contact resistivity to as low as 10(exp -5) ohm sq cm on natural semiconducting diamond with about 10(exp 16) boron atoms/cubic cm. In our Phase 1 SBIR program we investigated metal systems coupled with a shallow Si implant that would form low resistivity, high temperature stable metal silicides. We showed in our Phase 1 results that the barrier height of metals such as Pt, Ti and Mo were reduced when deposited on shallow Si implants and given a heat treatment at 500 C. The barrier height of Pt on diamond was reduced from 1.89 to 0.97 eV by annealing of a sputtered Pt contact on a Si implanted dose of 10(exp 15) cm(exp -2) sq A into the diamond surface. Using the same approach, the barrier height of Ti on diamond was reduced from 2.00 to 1.29 eV.

  18. Photoemission studies using femtosecond pulses for high brightness electron beams

    NASA Astrophysics Data System (ADS)

    Srinivasan-Rao, T.; Tsang, T.; Fischer, J.

    1990-06-01

    We present the results of a series of experiments where various metal photocathodes are irradiated with ultrashort laser pulses, whose characteristics are: (lambda) = 625 nm, (tau) = 100 fs, PRR = 89.5 MHz, H(nu) = 2 eV and average power 25 mW in each of the two beams. The quantum efficiency of the metals range from approximately 10(exp -12) to 10(exp -8) at a power density of 100 MW/sq cm at normal incidence. Since all the electrons are emitted due to multiphoton processes, these efficiencies are expected to increase substantially at large intensities. The efficiency at 100 MW/sq cm was increased by using p-polarized light at oblique incidence by approximately 20 x and by mediating the electron emission through surface plasmon excitation by approximately 10(exp 3) x. For the low intensities used in these experiments, the electron pulse duration is almost the same as the laser pulse duration for both the bulk and the surface plasmon mediated photoemission.

  19. The determination of HNO3 column amounts from tunable diode laser heterodyne spectrometer spectra taken at Jungfruajoch, Switzerland

    NASA Technical Reports Server (NTRS)

    Fogal, P. F.; Murcray, D. G.; Martin, N. A.; Swann, N. R.; Woods, P. T.; Mcelroy, C. T.

    1994-01-01

    In May of 1991 a tunable diode laser heterodyne spectrometer built by the National Physical Laboratory was operated at the International Scientific Station of the Jungfraujoch (46.5 deg N, 8.0 deg E, altitude 3.56 km). Nitric acid spectra in the region of 868 wavenumbers were recorded at sunset and sunrise on two separate days at a resolution of 0.0013 wavenumbers with a signal-to-noise ratio of approximately 130:1. A vertical column amount of HNO3 of 1.61 x 10(exp 16) molecules/sq cm was determined using an atmospheric transmission model developed at the University of Denver. The mean of a number of mid-latitude, northern hemisphere profiles was used as the initial profile for the inversion. A comparison of different initial profiles provides information on the sensitivity of the retrieved column amount of 1.61 x 10(exp 16) molecules/sq cm lies within the range of values published in the World Meteorological Organization Report no. 16 (1986), but is considerably larger than the value of (0.99 - 1.29) x 10(exp 16) reported by Rinsland et al. (1991) for June during the period 1986 to 1990.

  20. The fluorescence-dominated X-ray spectrum of the spiral galaxy NGC 6552

    NASA Technical Reports Server (NTRS)

    Fukazawa, Yasushi; Makishima, Kazuo; Ebisawa, Ken; Fabian, Andrew C.; Gendreau, Keith C.; Ikebe, Yasushi; Iwasawa, Kazushi; Kii, Tsuneo; Mushotzky, Richard F.; Ohashi, Takaya

    1994-01-01

    A hard X-ray source with a 2-10 keV flux of approximately 6 x 10(exp -13) ergs/sec/sq cm was detected with ASCA in the north ecliptic pole region. It is identified with the spiral galaxy NGC 6552 at a redshift of z = 0.026, which is optically classified as a Seyfert 2 galaxy. The X-ray spectrum consists of a series of atomic K-emission lines from (nearly-) neutral species of at least seven abundant elements, and a heavily absorbed (N(sub H) approx. = 6 x 10(exp 23)/sq cm) hard continuum. The iron line has an equivalent width as large as approximately 0.9 keV. Our results show that NGC 6552 is an extreme type 2 Seyfert galaxy, in which the fluorescent lines are produced when hard X-rays from a hidden active nucleus are reflected off thick cool matter into our line of sight. The intrinsic 2-10 keV luminosity of the nucleus is estimated to be at least 6 x 10(exp 42) ergs/s.

  1. Light hydrocarbons from plasma discharge in H2-He-CH4 - First results and Uranian auroral chemistry

    NASA Technical Reports Server (NTRS)

    Thompson, W. Reid; Henry, Todd; Khare, B. N.; Flynn, Luke; Schwartz, Joel

    1987-01-01

    The production of light hydrocarbons by precipitating magnetospheric electrons in the Uranian stratosphere is simulated in laboratory experiments. The products of continuous-flow glow discharges of H2-He-CH4 mixtures containing 0.0012 or 0.022 mol pct CH4 at pressures 0.63-57 mbar are trapped at 77 K, measured manometrically, and identified by gas chromatography and mass spectroscopy; the results are presented in tables and characterized in detail. The globally averaged rate for the production of higher hydrocarbons by this mechanism on Uranus is estimated as 3 x 10 to the 6th C/sq cm sec and shown to be similar to that for photochemical production, while the local rate for the auroral zones is significantly higher than the corresponding photochemical rate. A decrease in yield with increasing molecular complexity is also noted.

  2. Airborne spectrophotometry of Eta Carinae from 4.5 to 7.5 microns and a model for source morphology

    NASA Technical Reports Server (NTRS)

    Russell, Ray W.; Lynch, David K.; Hackwell, John A.; Rudy, Richard J.; Rossano, George S.; Castelaz, M. W.

    1987-01-01

    Spectrophotometric observations of Eta Car between 4.5 and 7.5 microns show a featureless thermal-like spectrum with no fine-structure lines or broad emission or absorption features. The color temperature of the spectrum is approximately 375 K. High spatial resolution maps at 3.5, 4.8, and 10 microns obtained from the ground are used to discuss the dust distribution and temperature structure, and to present a model for general source morphology. The upper limit to the brightness of the forbidden Ar II fine-structure emission line at 6.98 microns is less than 7 x 10 to the -16th W/sq cm, which still allows for a significant overabundance of argon and is consistent with the evolved nature of the source.

  3. Electrical conductivity of poly(3,4-ethylenedioxythiophene):p-toluene sulfonate films hybridized with reduced graphene oxide

    PubMed Central

    2014-01-01

    Reduced graphene oxide-poly(3,4-ethylenedioxythiophene):p-toluene sulfonate (rGO-PEDOT:PTS) hybrid electrode films were synthesized directly on a substrate by interfacial polymerization between an oxidizing solid layer and liquid droplets of 3,4-ethylenedioxythiophene (EDOT) produced by electrospraying. The EDOT reduced the graphene oxide by donating electrons during its transformation into PEDOT:PTS, and hybrid films consisting of rGO distributed in a matrix of PEDOT:PTS were obtained. These rGO-PEDOT:PTS hybrid films showed excellent electrical conductivities as high as 1,500 S/cm and a sheet resistance of 70 Ω sq-1. The conductivity values are up to 50% greater than those of films containing conductive PEDOT:PTS alone. These results confirm that highly conductive rGO-PEDOT:PTS hybrid films can potentially be used as organic transparent electrodes. PMID:25520593

  4. Relation between growth rate and structure of graphene grown in a 4″ showerhead chemical vapor deposition reactor.

    PubMed

    Bekdüz, B; Beckmann, Y; Meier, J; Rest, J; Mertin, W; Bacher, G

    2017-04-07

    The chemical vapor deposition (CVD) growth of graphene on copper is controlled by a complex interplay of substrate preparation, substrate temperature, pressure and flow of reactive gases. A large variety of recipes have been suggested in literature, often quite specific to the reactor, which is being used. Here, we report on a relation between growth rate and quality of graphene grown in a scalable 4″ CVD reactor. The growth rate is varied by substrate pre-treatment, chamber pressure, and methane to hydrogen (CH4:H2) ratio, respectively. We found that at lower growth rates graphene grains become hexagonal rather than randomly shaped, which leads to a reduced defect density and a sheet resistance down to 268 Ω/sq.

  5. Absorption in X-ray spectra of high-redshift quasars

    NASA Technical Reports Server (NTRS)

    Elvis, Martin; Fiore, Fabrizio; Wilkes, Belinda; Mcdowell, Jonathan; Bechtold, Jill

    1994-01-01

    We present evidence that X-ray absorption is common in high-redshift quasars. We have studied six high-redshift (z approximately 3) quasars with the ROSAT Position Sensitive Proportional Counter (PSPC) of which four are in directions of low Galactic N(sub H). Three out of these four show excess absorption, while only three in approximately 50 z approximately less than 0.4 quasars do, indicating that such absorption must be common, but not ubiquitous, at high redshifts, and that the absorbers must lie at z greater than 0.4. The six quasars were: S5 0014+81, Q0420-388, PKS 0438-436, S4 0636+680. PKS 2000-330, PKS 2126-158, which have redshifts between 2.85 and 3.78. PKS 0438-436 and PKS 2126-158 show evidence for absorption above the local Galactic value at better than 99.999% confidence level. If the absorber is at the redshift of the quasar, then values of N(sub H) = (0.86(+0.49, -0.28)) x 10(exp 22) atoms/sq cm for PKS 0438-436, and N(sub H) = (1.45(+1.20, -0.64)) x 10(exp 22) atoms/ sq cm for PKS 2126-158, are implied, assuming solar abundances. The spectrum of S4 0636+680 also suggests the presence of a similarly large absorption column density at the 98% confidence level. This absorption reverses the trend for the most luminous active galactic nuclei (AGN) to have the least X-ray absorption, so a new mechanism is likely to be responsible. Intervening absorption due to damped Lyman(alpha) systems is a plausible cause. We also suggest, as an intrinsic model, that intracluster material, e.g., a cooling flow, around the quasar could account for both the X-ray spectrum and other properties of these quasars. All the quasars are radio-loud and three are gigahertz peaked (two of the three showing absorption). No excess absorption above the Galactic value is seen toward Q0420-388. This quasar has two damped Lyman(alpha) systems at z = 3.08. The limit on the X-ray column density implies a low ionization fraction, N(H I)/N(H) approximately greater than 4 x 10(exp -3) (3

  6. Evaluation of Several Space Lubricants using a Vacuum Four-Ball Tribometer

    NASA Technical Reports Server (NTRS)

    Jones, William R., Jr.; Poslowski, Agnieszka K.; Shogrin, Bradley A.; Herrera-Fierro, Pilar; Jansen, Mark J.

    1998-01-01

    The friction and wear behavior of seven space lubricants was investigated under boundary lubrication conditions using a vacuum four-ball tribometer. Three of the lubricants were perfluoropolyethers (143AC, S-200, and Z-25). Three were synthetic hydrocarbons (a multiply alkylated cyclopentane, 2001a), and a formulated version with an antiwear and an antioxidant additive (2001). The third hydrocarbon was an unformulated polyalphaolefin (PAO-100). An unformulated silahydrocarbon (SiHC) was also evaluated. Test conditions included: a pressure less than 6.7 x 10(exp 4) Pa, a 200 N load, a sliding velocity of 28.8 mm/sec (100 RPM), and room temperature (approx. 23 C). The wear rate for each lubricant was determined from the slope of wear volume as a function of sliding distance. The lowest wear rate (0.033 x 10(exp-9) cu mm/mm) was obtained with the silahydrocarbon. The formulated synthetic hydrocarbon had a wear rate off O.037 x 10(exp -9)cu mm/mm, which was a 36% reduction compared to the unformulated fluid. The polyalphaolefin had the highest wear rate of the non-PFPE fluids. Of the perfluoropolyethers (PFPEs), wear rates decreased by about 50% from Z-25 (1.7 x 10(exp -9)cu mm/mm) to S-200 (0.70 x 10(exp -9)cu mm/mm) to 143AC (0.21 x 10(exp -9)cu mm/mm).

  7. The Discovery Outburst of the X-Ray Transient IGR J17497-2821 Observed with RXTE and ATCA

    NASA Technical Reports Server (NTRS)

    Rodriquez, Jerome; Bel, Marion Cadolle; Tomsick, John A.; Corbel, Stephane; Brocksopp, Catherine; Paizis, Ada; Shaw, Simon E.; Bodaghee, Arash

    2007-01-01

    We report the results of a series of RXTE and ATCA observations of the recently discovered X-ray transient IGR J17497-2821. Our 3-200 keV PCA+HEXTE spectral analysis shows very little variations over a period of approx.10 days around the maximum of the outburst. IGR J17497-2821 is found in a typical low-hard state (LHS) of X-ray binaries (XRBs), well represented by an absorbed Comptonized spectrum with an iron edge at about 7 keV. The high value of the absorption (approx.4 x 10(exp 22/sq cm suggests that the source is located at a large distance, either close to the Galactic center or beyond. The timing analysis shows no particular features, while the shape of the power density spectra is also typical of the LHS of XRBs, with apprrox.36% rms variability. No radio counterpart is found down to a limit of 0.21 mJy at 4.80 and 8.64 GHz. Although the position of IGR J17497-2821 in the radio to X-ray flux diagram is well below the correlation usually observed in the LHS of black holes, the comparison of its X-ray properties with those of other sources leads us to suggest that it is a black hole candidate.

  8. Observations of 1E 1740.7-2942 with ROSAT and the VLA

    NASA Technical Reports Server (NTRS)

    Heindl, William A.; Prince, Thomas A.; Grunsfeld, John M.

    1994-01-01

    We have observed the Galactic black hole candidate 1E 1740.7-2942 in X-rays with both the ROSAT high resolution imager (HRI) and position-sensitive proportional counter (PSPC) and at 1.5 and 4.9 GHz with the very large array (VLA). From the HRI observation we derive a position for 1E 1740.7-2942 of right ascension = 17(exp h) 43(exp m) 54.9(exp s), declination = -29 deg 44 min 45.3 sec (J2000), with a 90% confidence error circle of radius 8.5 sec. Thermal bremsstrahlung fits to the PSPC data yield a column density of 1.12 + 1.51 or -0.18 X 10(exp 23)/ sq cm, consistent with earlier X-ray measurements. The VLA observations of 4.9 GHz revealed two sources. Source A, which is the core of a double aligned radio jet source (Mirabel et al. 1992), lies within the ROSAT error circle, further confirming its identification with 1E 1740.7-2942.

  9. Observations of 1E 1740.7-2942 with ROSAT and the VLA

    NASA Technical Reports Server (NTRS)

    Heindl, William A.; Prince, Thomas A.; Grunsfeld, John M.

    1994-01-01

    We have observed the Galactic black hole candidate 1E 1740.7-2942 in X-rays with both the ROSAT HRI and PSPC and at 1.5 and 4.9 GHz with the VLA. From the HRI observation we derive a position for 1E 1740.7-2942 of right ascension = 17 h 43 m 54.9 s, declination = -29 deg 44 min 45.3 sec (J2000), with a 90% confidence error circle of radius 8.5 min. Thermal bremsstrahlung fits to the PSPC data yield a column density of 1.12+1.51/-0.18 x 10(exp 23)/sq cm, consistent with earlier X-ray measurements. The VLA observation of 4.9 GHz revealed two sources. Source A, which is the core of a double aligned radio jet source (Mirabel et al. 1992), lies within the ROSAT error circle, further confirming its identification with 1E 1740.7-2942.

  10. Flux creep in Bi2Sr2CaCu2O8(sub +x) single crystals

    NASA Technical Reports Server (NTRS)

    Agostinelli, E.; Balestrino, G.; Fiorani, D.; Muzi, R.; Paroli, P.; Tejada, J.; Testa, A. M.

    1990-01-01

    The results of a magnetic study on a Bi2Sr2CaCu2O(8+x) single crystal are reported. Low field susceptibility (dc and ac), magnetization cycles and time dependent measurements were performed. With increasing the temperature the irreversible regime of the magnetization cycles is rapidly restricted to low fields, showing that the critical current J(sub c) becomes strongly field dependent well below T(sub c). At 2.4 K the critical current in zero field, determined from the remanent magnetization by using the Bean formula for the critical state, is J(sub c) = 2 10(exp 5) A/sq cm. The temperature dependence of J(sub c) is satisfactorily described by the phenomenological law J(sub c) = J(sub c) (0) (1 - T/T(sub c) (sup n), with n = 8. The time decay of the zero field cooled magnetization and of the remanent magnetization was studied at different temperatures for different magnetic fields. The time decay was found to be logarithmic in both cases, at least at low temperatures. At T = 4.2 K for a field of 10 kOe applied parallel to the c axis, the average pinning energy, determined by using the flux creep model, is U(sub o) = 0.010 eV.

  11. Observations of the Large Magellanic Cloud in high-energy gamma rays

    NASA Technical Reports Server (NTRS)

    Sreekumar, P.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

    1992-01-01

    The LMC provides a valuable site to study gamma-ray production, intensity, and distribution in an external galaxy. Using 4 weeks of data from the Energetic Gamma Ray Experiment Telescope (EGRET) aboard the Compton Gamma Ray Observatory, high-energy gamma-ray emission was detected for the first time from the LMC region. These gamma rays are believed to be produced primarily through the interaction of cosmic rays with interstellar matter. Hence, combined with a knowledge of the interstellar matter distribution, they can provide a direct measure of the cosmic-ray density in an external galaxy. The results obtained from EGRET observations indicate that the level of cosmic rays in the LMC is comparable to that in our Galaxy. The integrated flux above 100 MeV is (1.9 +/- 0.4) x 10 exp -7 photons/(sq cm s). The measured flux suggests a cosmic-ray density level consistent with that expected from a quasi-stable equilibrium model. This is the first detection of a normal galaxy outside the Milky Way in high-energy gamma rays.

  12. Detection of H3(+) from Uranus

    NASA Technical Reports Server (NTRS)

    Trafton, L. M.; Geballe, T. R.; Miller, S.; Tennyson, J.; Ballester, G. E.

    1993-01-01

    The detection of H3(+) in Uranus is reported. Using the CGS4 spectrometer on the UKIRT telescope, we clearly detected 11 emission features of the H3(+) fundamental vibration-rotation band between 3.89 and 4.09 microns. These features are composed primarily of lines from the Q-branch; the strongest of them is the Q(3) blend at 3.985 microns. Analysis of these features indicates a rotational temperature of 740 +/- 25 K, an ortho-H3(+) fraction of 0.51 +/- 0.03, and a disk-averaged H3(+) column abundance of 6.5 x 10 exp 10 (+/- 10 percent) molecules/sq cm. Comparison is made with Jupiter, Saturn, and Neptune. A detection of the H2 1-0 S(1) line in Uranus and an upper limit to H3(+) emission from Neptune also are reported. The rate of energy deposition into Uranus appears to be significantly higher than the rate reported during the Voyager 2 flyby in January of 1986.

  13. Low Earth orbital atomic oxygen environmental simulation facility for space materials evaluation

    SciTech Connect

    Stidham, C.R.; Banks, B.A.; Stueber, T.J.; Dever, J.A.; Rutledge, S.K.; Bruckner, E.J.

    1993-05-01

    Simulation of low Earth orbit atomic oxygen for accelerated exposure in ground-based facilities is necessary for the durability evaluation of space power system component materials for Space Station Freedom (SSF) and future missions. A facility developed at the National Aeronautics and Space Administrations's (NASA) Lewis Research Center provides accelerated rates of exposure to a directed or scattered oxygen beam, vacuum ultraviolet (VUV) radiation, and offers in-situ optical characterization. The facility utilizes an electron-cyclotron resonance (ECR) plasma source to generate a low energy oxygen beam. Total hemispherical spectral reflectance of samples can be measured in situ over the wavelength range of 250 to 2500 nm. Deuterium lamps provide VUV radiation intensity levels in the 115 to 200 nm range of three to five equivalent suns. Retarding potential analyses show distributed ion energies below 30 electron volts (eV) for the operating conditions most suited for high flux, low energy testing. Peak ion energies are below the sputter threshold energy (approximately 30 eV) of the protective coatings on polymers that are evaluated in the facility, thus allowing long duration exposure without sputter erosion. Neutral species are expected to be at thermal energies of approximately .04 eV to .1 eV. The maximum effective flux level based on polyimide Kapton mass loss is 4.4 x 10 exp 6 atoms/((sq. cm)*s), thus providing a highly accelerated testing capability.

  14. Low Earth orbital atomic oxygen environmental simulation facility for space materials evaluation

    NASA Technical Reports Server (NTRS)

    Stidham, Curtis R.; Banks, Bruce A.; Stueber, Thomas J.; Dever, Joyce A.; Rutledge, Sharon K.; Bruckner, Eric J.

    1993-01-01

    Simulation of low Earth orbit atomic oxygen for accelerated exposure in ground-based facilities is necessary for the durability evaluation of space power system component materials for Space Station Freedom (SSF) and future missions. A facility developed at the National Aeronautics and Space Administrations's (NASA) Lewis Research Center provides accelerated rates of exposure to a directed or scattered oxygen beam, vacuum ultraviolet (VUV) radiation, and offers in-situ optical characterization. The facility utilizes an electron-cyclotron resonance (ECR) plasma source to generate a low energy oxygen beam. Total hemispherical spectral reflectance of samples can be measured in situ over the wavelength range of 250 to 2500 nm. Deuterium lamps provide VUV radiation intensity levels in the 115 to 200 nm range of three to five equivalent suns. Retarding potential analyses show distributed ion energies below 30 electron volts (eV) for the operating conditions most suited for high flux, low energy testing. Peak ion energies are below the sputter threshold energy (approximately 30 eV) of the protective coatings on polymers that are evaluated in the facility, thus allowing long duration exposure without sputter erosion. Neutral species are expected to be at thermal energies of approximately .04 eV to .1 eV. The maximum effective flux level based on polyimide Kapton mass loss is 4.4 x 10 exp 6 atoms/((sq. cm)*s), thus providing a highly accelerated testing capability.

  15. CGRO/OSSE observations of the Cassiopeia A Supernova remnant

    NASA Technical Reports Server (NTRS)

    The, L.-S.; Leising, M. D.; Clayton, D. D.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Jung, G. V.; Grabelsky, D. A.; Purcell, W. R.

    1995-01-01

    Cassipeia A, the youngest known supernova remnant in the Galaxy and a strong radio and X-ray source, was observed by OSSE 1992 July 16-August 6. Its close distance (approximately 3 kpc) and its young age (approximately 300 yr) make Cas A the best candidate among known supernova remnants for detecting Ti-44 gamma-ray lines. We find no evidence of emission at 67.9 keV, 78.4 keV, or 1.157 MeV, the three strongest Ti-44 decay lines. From simultaneous fits to the three lines our 99% confidence upper limit to the flux in each line is 5.5 x 10(exp -5) gamma/sq cm s. We also report upper limits for the 4.44 MeV C-12 nuclear de-excitation line, which could be produced by interactions of acclerated particles in the supernova remnant, and for the hard X-ray continuum.

  16. What's on the Surface? Physics and Chemistry of Delta-Doped Surfaces

    NASA Technical Reports Server (NTRS)

    Hoenk, Michael

    2011-01-01

    Outline of presentation: 1. Detector surfaces and the problem of stability 2. Delta-doped detectors 3. Physics of Delta-doped Silicon 4. Chemistry of the Si-SiO2 Interface 5. Physics and Chemistry of Delta-doped Surfaces a. Compensation b. Inversion c. Quantum exclusion. Conclusions: 1. Quantum confinement of electrons and holes dominates the behavior of delta-doped surfaces. 2. Stability of delta-doped detectors: Delta-layer creates an approx 1 eV tunnel barrier between bulk and surface. 3. At high surface charge densities, Tamm-Shockley states form at the surface. 4. Surface passivation by quantum exclusion: Near-surface delta-layer suppresses T-S trapping of minority carriers. 5. The Si-SiO2 interface compensates the surface 6. For delta-layers at intermediate depth, surface inversion layer forms 7. Density of Si-SiO2 interface charge can be extremely high (>10(exp 14)/sq cm)

  17. Transition from Gaseous Compounds to Aerosols in Titan's Atmosphere

    NASA Technical Reports Server (NTRS)

    Lebonnois, Sebastien; Bakes, E. L. O.; McKay, Christopher P.; DeVincenzi, Donald (Technical Monitor)

    2002-01-01

    We investigate the chemical transition of simple molecules like C2H2 and HCN into aerosol particles in the context of Titan's atmosphere. Experiments that synthesize analogs (tholins) for these aerosols can help understand and constrain these polymerization mechanisms. Using information available from these experiments, we suggest chemical pathways that can link simple molecules to macromolecules, that will be the precursors to aerosol particles: polymers of acetylene and cyanoacetylene, polycyclic aromatics (PAHs), polymers of HCN and other nitriles, and polynes. Although our goal here is not to build a detailed kinetic model for this transition, we propose parameterizations to estimate the production rates of these macromolecules, their C/N and C/H ratios, and the loss of parent molecules (C2H2, HCN, HC3N and other nitriles, C6H6) from the gas phase to the haze. We use a 1-dimensional photochemical model of Titan's atmosphere to estimate the formation rate of precursors macromolecules. We find a production zone slightly lower than 200 km altitude with a total production rate of 4 x 10(exp -14) g/ sq cm s and a C/N approx. = 4. These results are compared with experimental data, and to microphysical models requirements. The Cassini/Huygens mission will bring a detailed picture of the haze distribution and properties, that will be a great challenge for our understanding of those chemical processes.

  18. The X-ray Emitting Components towards l = 111 deg: The Local Hot Bubble and Beyond

    NASA Technical Reports Server (NTRS)

    Kuntz, K. D.; Snowden, S. L.

    2006-01-0