5,963 research outputs found

    Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 2: Programmer's manual

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    The six month effort was responsible for the development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs. The program NOMNAL targets a transfer trajectory from earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty

    In-situ monitoring for CVD processes

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    Aiming towards process control of industrial high yield/high volume CVD reactors, the potential of optical sensors as a monitoring tool has been explored. The sensors selected are based on both Fourier transform infrared spectroscopy (FTIR) and tunable diode laser spectroscopy (NIR-DLS). The former has the advantage of wide spectral capability, and well established databases. NIR-DLS spectroscopy has potentially high sensitivity, laser spatial resolution, and the benefits of comparatively easier integration capabilities-including optical fibre compatibility. The proposed technical approach for process control is characterised by a 'chemistry based' feedback system with in-situ optical data as input information. The selected optical sensors continuously analyze the gas phase near the surface of the growing layer. The spectroscopic data has been correlated with process performance and layer properties which, in turn establish data basis for process control. The new process control approach is currently being verified on different industrialised CVD coaters. One of the selected applications deals with the deposition of SnO2 layers on glass based on the oxidation of (CH3)2SnCl2, which is used in high volume production for low-E glazing

    Direct carrier detection by in situ suppression hybridization with cosmid clones of the Duchenne/Becker muscular dystrophy locus

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    A basic problem in genetic counseling of families with Duchenne/Becker muscular dystrophy (DMD/BMD) concerns the carrier status of female relatives of an affected male. In about 60% of these patients, deletions of one or more exons of the dystrophin gene can be identified. These deletions preferentially include exon 45, which can be detected by multiplex polymerase chain reaction (PCR) and Southern blot analysis of genomic cosmid clones that map to this critical region. As a new approach for definitive carrier detection, we have performed chromosomal in situ suppression (CISS) hybridization with these cosmid clones in female relatives of four unrelated patients. In normal females, most metaphases showed signals on both×chromosomes, whereas only one×chromosome was labeled in carriers. Our results demonstrate that CISS hybridization can define the carrier status in female relatives of DMD patients exhibiting a deletion in the dystrophin gene

    Possibility of Recoating of Impurities on Product Kaolin during Froth Flotation - HRTEM-EDS Study

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    Attempts were made to remove the Fe, Ti minerals from Gujarat kaolin by SC-HGMS and ultraflotation to improve the optical properties. The removal of Fe was higher by SC-HGMS, but that of Ti was almost the same by both techni-ques. The Fe content of the products was relatively low, but the brightness was lower than the expected. A drastic improvement in brightness was observed for the SC-HGMS product compared to the ultra flotation product. One of the probable reasons for the low enhancement in brightness by flotation was thought to be recoating of the impurities on the clay surface during flotation. XPS study conducted on the flotation product ruled out the possibility of such a coating. HRTEM-EDS analyses showed that most of the titania is present in the form of anatase particles of very small size. A part of the Fe forms independent parti-cles of goethite /hematite having nano size. Rest of the Fe is found to be closer to anatase or kaolinite particles either as a part of the structure or nano sized independ-ent particles adhering to the surface and hence is not easily separated. The ultra fine grains of Fe stained ana-tase remaining in the kaolinite surface after flotation is found to have a strong pigment effect. During flotation, high shear energy is given for dispersion and conditioning which is possibly reducing the particle size to sub-micron / nano level. The dissatisfying brightness of the flotation product is attributed to the presence of these fine / colloidal impurities. Fe content in the product samples is relatively low and its influence on brightness is probably smaller than that of the Fe stained anatase. The organic matter and ferriferous smectite identified in the sample even at small percentages may also have a pig-ment effect due to their dark color and colloidal distri-bution

    Components of the dilepton continuum in Pb+Pb collisions at sNN=2.76\sqrt{s_{_{NN}}} = 2.76 TeV

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    The dilepton invariant mass spectrum measured in heavy-ion collisions includes contributions from important QGP probes such as thermal radiation and the quarkonium (J/ψJ/\psi, ψ′\psi' and Υ\Upsilon) states. Dileptons coming from hard qqˉq \bar q scattering, the Drell-Yan process, contribute in all mass regions. In heavy-ion colliders, such as the LHC, semileptonic decays of heavy flavor hadrons provide a substantial contribution to the dilepton continuum. The dilepton continuum can give quantitative information about heavy quark yields and their modification in the medium and thus it is important to know all different sources which populate the continuum. In the present study, we calculate ccˉc \bar c and bbˉb \bar b production and determine their contributions to the dilepton continuum in Pb+Pb collisions at sNN=2.76\sqrt{s_{_{NN}}} = 2.76 TeV with and without including heavy quark energy loss. We also calculate the rates for Drell-Yan and thermal dilepton production. The contributions to the continuum from these dilepton sources are studied in the kinematic ranges relevant for the LHC detectors. The relatively high pTp_T cutoff for single leptons excludes most dileptons produced by the thermal medium. Heavy flavors are the dominant source of dilepton production in all the kinematic regimes except at forward rapidities where Drell-Yan start dominating in high mass range beyond 10 GeV/c2c^2.Comment: 18 pages, 9 figure

    Screening and Anti-Screening Effects in J/psi Production on Nuclei

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    The nuclear effects in J/psi hadro- and electroproduction on nuclei are considered in framework of reggeon approach. It is shown that screening regime which holds for electroproduction at x_F > 0.7 and for hadroproduction at x_F > -(0.3-0.4) is changed with anti-screening regime for smaller x_F values.Comment: 6 pages, 6 figures. Small changes in wordin

    Spin-wave propagation in a microstructured magnonic crystal

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    Transmission of microwave spin waves through a microstructured magnonic crystal in the form of a permalloy waveguide of a periodically varying width was studied experimentally and theoretically. The spin wave characteristics were measured by spatially-resolved Brillouin light scattering microscopy. A rejection frequency band was clearly observed. The band gap frequency was controlled by the applied magnetic field. The measured spin-wave intensity as a function of frequency and propagation distance is in good agreement with a model calculation.Comment: 4 pages, 3 figure

    The Population of Weak Mg II Absorbers I. A Survey of 26 QSO HIRES/Keck Spectra

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    We present a search for "weak" MgII absorbers [those with W_r(2796) < 0.3 A in the HIRES/Keck spectra of 26 QSOs. We found 30, of which 23 are newly discovered. The spectra are 80% complete to W_r(2796) = 0.02 A and have a cumulative redshift path of ~17.2 for the redshift range 0.4 < z < 1.4. The number of absorbers per unit redshift, dN/dz, is seen to increase as the equivalent width threshold is decreased; we obtained dN/dz = 1.74+/-0.10 for our 0.02 <= W_r(2796) < 0.3 A sample. The equivalent width distribution follows a power law with slope -1.0; there is no turnover down to W_r(2796) = 0.02 A at = 0.9. Weak absorbers comprise at least 65% of the total MgII absorption population, which outnumbers Lyman limit systems (LLS) by a factor of 3.8+/-1.1; the majority of weak MgII absorbers must arise in sub-LLS environments. Tentatively, we predict that ~5% of the Lyman-alpha forest clouds with W_r(1215) > 0.1 A will have detectable MgII absorption to W_r,min(2796) = 0.02 A and that this is primarily a high-metallicity selection effect (Z/Z_sun] > -1). This implies that MgII absorbing structures figure prominently as tracers of sub-LLS environments where gas has been processed by stars. We compare the number density of W_r(2796) > 0.02 A absorbers with that of both high and low surface brightness galaxies and find a fiducial absorber size of 35h^-1 to 63h^-1 kpc, depending upon the assumed galaxy population and their absorption properties. The individual absorbing "clouds" have W_r(2796) <= 0.15 A and their narrow (often unresolved) line widths imply temperatures of ~25,000 K. We measured W_r(1548) from CIV in FOS/HST archival spectra and, based upon comparisons with FeII, found a range of ionization conditions (low, high, and multi-phase) in absorbers selected by weak MgII.Comment: Accepted Version: 43 pages, PostScript figures embedded; accepted to ApJ; updated version includes analysis of CIV absorptio
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