39,762 research outputs found

    Investigation of an axial-excursion transducer for squeeze-film bearings

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    Resonant frequencies and characteristic bearing cone motion of axial-excursion transducer for squeeze-film gas bearing - drive voltage, preload, bearing mass, and mounting ring effect

    The Impact of Type Ia Supernova Ejecta on Binary Companions

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    We present adaptive mesh refinement (AMR) hydrodynamical simulations of the interaction between Type Ia supernovae and their companion stars within the context of the single-degenerate model. Results for 3D red-giant companions without binary evolution agree with previous 2D results by Marietta et al. We also consider evolved helium-star companions in 2D. For a range of helium-star masses and initial binary separations, we examine the mass unbound by the interaction and the kick velocity delivered to the companion star. We find that unbound mass versus separation obeys a power law with index between -3.1 and -4.0, consistent with previous results for hydrogen-rich companions. Kick velocity also obeys a power-law relationship with binary separation, but the slope differs from those found for hydrogen-rich companions. Assuming accretion via Roche-lobe overflow, we find that the unbound helium mass is consistent with observational limits. Ablation (shock heating) appears to be more important in removing gas from helium-star companions than from hydrogen-rich ones, though stripping (momentum transfer) dominates in both cases.Comment: 6 pages, 2 figures, to appear in the proceedings of the conference "Binary Star Evolution: Mass Loss, Accretion, and Mergers" at Mykonos, Greece, June 22-25, 201

    A Novel Sequence-Based Antigenic Distance Measure for H1N1, with Application to Vaccine Effectiveness and the Selection of Vaccine Strains

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    H1N1 influenza causes substantial seasonal illness and was the subtype of the 2009 influenza pandemic. Precise measures of antigenic distance between the vaccine and circulating virus strains help researchers design influenza vaccines with high vaccine effectiveness. We here introduce a sequence-based method to predict vaccine effectiveness in humans. Historical epidemiological data show that this sequence-based method is as predictive of vaccine effectiveness as hemagglutination inhibition (HI) assay data from ferret animal model studies. Interestingly, the expected vaccine effectiveness is greater against H1N1 than H3N2, suggesting a stronger immune response against H1N1 than H3N2. The evolution rate of hemagglutinin in H1N1 is also shown to be greater than that in H3N2, presumably due to greater immune selection pressure.Comment: 26 pages, 7 figures, 2 tables, supplemen

    Microscopic origin of the next generation fractional quantum Hall effect

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    Most of the fractions observed to date belong to the sequences ν=n/(2pn±1)\nu=n/(2pn\pm 1) and ν=1−n/(2pn±1)\nu=1-n/(2pn\pm 1), nn and pp integers, understood as the familiar {\em integral} quantum Hall effect of composite fermions. These sequences fail to accommodate, however, many fractions such as ν=4/11\nu=4/11 and 5/13, discovered recently in ultra-high mobility samples at very low temperatures. We show that these "next generation" fractional quantum Hall states are accurately described as the {\em fractional} quantum Hall effect of composite fermions

    Analysis, design, and prototype development of squeeze-film bearings for AB-5 gyro Final report phase 2, design, fabrication and evaluation of prototypes

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    Squeeze-film bearing transducers with piezoceramic cylinders for AB-5 gyro - design, fabrication, and testing of cylindrical journal and annular bearing prototype
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