3,511 research outputs found

    Study of the Barringer Refractor Plate Correlation Spectrometer as a remote sensing instrument

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    Barringer refractor plate correlation spectrometer as remote sensing instrument of pollutant gases in atmospher

    Hypervelocity impacts into stainless-steel tubes armored with reinforced beryllium

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    Hypervelocity impact into stainless steel tubes armored with reinforced berylliu

    Solar-radiation-induced damage to optical properties of ZnO-type pigments Technical summary report, Jul. 1966 - Feb. 1968

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    Mechanisms of solar radiation damage to optical properties in zinc oxide pigments in visible and infrared region

    Hypervelocity impact damage characteristics in beryllium and graphite plates and tubes

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    Hypervelocity impact damage characteristics in beryllium and graphite plates and tube

    Phase Closure Nulling: results from the 2009 campaign

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    We present here a new observational technique, Phase Closure Nulling (PCN), which has the potential to obtain very high contrast detection and spectroscopy of faint companions to bright stars. PCN consists in measuring closure phases of fully resolved objects with a baseline triplet where one of the baselines crosses a null of the object visibility function. For scenes dominated by the presence of a stellar disk, the correlated flux of the star around nulls is essentially canceled out, and in these regions the signature of fainter, unresolved, scene object(s) dominates the imaginary part of the visibility in particular the closure phase. We present here the basics of the PCN method, the initial proof-of-concept observation, the envisioned science cases and report about the first observing campaign made on VLTI/AMBER and CHARA/MIRC using this technique.Comment: To be published in the proceedings of the SPIE'2010 conference on "Optical and Infrared Interferometry II

    Strong Near-Infrared Emission Interior to the Dust-Sublimation Radius of Young Stellar Objects MWC275 and AB Aur

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    Using the longest optical-interferometeric baselines currently available, we have detected strong near-infrared (NIR) emission from inside the dust-destruction radius of Herbig Ae stars MWC275 and AB Aur. Our sub-milli-arcsecond resolution observations unambiguously place the emission between the dust-destruction radius and the magnetospheric co-rotation radius. We argue that this new component corresponds to hot gas inside the dust-sublimation radius, confirming recent claims based on spectrally-resolved interferometry and dust evaporation front modeling.Comment: 12 pages, 4 figures, Accepted for publication in ApJ

    The effect of prolonged simulated non- gravitational environment on mineral balance in the adult male, volume 1 Final report

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    Effect of prolonged bed rest with simulated weightlessness on mineral balance in male adult - Vol.

    Pressure Driven Flow of Polymer Solutions in Nanoscale Slit Pores

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    Polymer solutions subject to pressure driven flow and in nanoscale slit pores are systematically investigated using the dissipative particle dynamics approach. We investigated the effect of molecular weight, polymer concentration and flow rate on the profiles across the channel of the fluid and polymer velocities, polymers density, and the three components of the polymers radius of gyration. We found that the mean streaming fluid velocity decreases as the polymer molecular weight or/and polymer concentration is increased, and that the deviation of the velocity profile from the parabolic profile is accentuated with increase in polymer molecular weight or concentration. We also found that the distribution of polymers conformation is highly anisotropic and non-uniform across the channel. The polymer density profile is also found to be non-uniform, exhibiting a local minimum in the center-plane followed by two symmetric peaks. We found a migration of the polymer chains either from or towards the walls. For relatively long chains, as compared to the thickness of the slit, a migration towards the walls is observed. However, for relatively short chains, a migration away from the walls is observed.Comment: 11 pages, 13 figure

    Bacterial evolution: Resistance is a numbers game

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    Plasmids are well known for spreading antibiotic-resistance genes between bacterial strains. Recent experiments show that they can also act as catalysts for evolutionary innovation, promoting rapid evolution of novel antibiotic resistance
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