6,684 research outputs found

    Eclipsing Binary Stars from Space

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    We have begun a programme to obtain high-precision photometry of bright detached eclipsing binary (dEB) stars with the Wide field InfraRed Explorer (WIRE) satellite. Due to the small aperture of WIRE only stars brighter than V=6 can be observed. We are collecting data for about a dozen dEB targets and here we present preliminary results for three of them. We have chosen dEBs with primary components of B and early A type. One of our aims is to combine the information from the light curve analyses of the eclipses with asteroseismic information from the analysis of the pulsation of the primary component.Comment: 4 pages, 3 figures. To appear in conference proceedings for IAU Symposium No. 240: Binary Stars as Critical Tools & Tests in Contemporary Astrophysics, eds. W. Hartkopf, E. Guinan & P. Harmane

    Mice Do Not Take Bribes

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    This paper explores the empirical association between internet use, e-government and corruption in a large panel of countries covering the 1998-2003 period. We show that higher numbers of internet users and higher levels of e-government are associated with significantly lower levels of corruption. Controlling for most variables used in previous work on corruption and addressing the endogeneity issue, results are shown to be robust and to carry economic significance. This leads us to conclude that well-designed ICT policies are likely to bring substantial benefits in the fight against corruption.corruption; ICT; internet; e-government

    The elastic I=3/2I=3/2 pp-wave nucleon-pion scattering amplitude and the Δ(1232)\Delta(1232) resonance from Nf=2+1N_{\mathrm{f}}=2+1 lattice QCD

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    We present the first direct determination of meson-baryon resonance parameters from a scattering amplitude calculated using lattice QCD. In particular, we calculate the elastic I=3/2I=3/2, pp-wave nucleon-pion amplitude on a single ensemble of Nf=2+1N_{\mathrm{f}}=2+1 Wilson-clover fermions with mπ=280MeVm_{\pi}=280\mathrm{MeV} and mK=460MeVm_{K}=460\mathrm{MeV}. At these quark masses, the Δ(1232)\Delta(1232) resonance pole is found close to the N−πN-\pi threshold and a Breit-Wigner fit to the amplitude gives gΔNπBW=19.0(4.7)g^{\mathrm{BW}}_{\Delta N\pi}=19.0(4.7) in agreement with phenomenological determinations.Comment: 7 pages, 2 figures. Agrees with published version, one additional phase shift point and clarification of different coupling convention

    Exobiology: The NASA program

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    The goal of NASA's Exobiology Program is to understand the origin, evolution, and distribution of life in the universe. To do this, the Exobiology Program seeks to provide a critical framework and some key research to allow NASA to bear the combined talents and capabilities of the agency and the scientific community, and the unique opportunities afforded by space exploration. To provide structure and direction to the quest for answers, the Exobiology Program has instituted a comprehensive research program divided into four elements which are being implemented at several of NASA's research centers and in the university community. These program elements correspond to the four major epochs in the evolution of living systems: (1) cosmic evolution of the biogenic compounds; (2) prebiotic evolution; (3) origin and early evolution of life; and (4) evolution of advanced life. The overall research program is designed to trace the pathways leading from the origin of the universe through the major epochs in the story of life

    The Politics of Ambivalence and Gambling in Copenhagen

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    The Dynamics of Shame in the Eden Narrative

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    Exploiting symmetries in the modeling and analysis of tires

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    A computational procedure is presented for reducing the size of the analysis models of tires having unsymmetric material, geometry and/or loading. The two key elements of the procedure when applied to anisotropic tires are: (1) decomposition of the stiffness matrix into the sum of an orthotropic and nonorthotropic parts; and (2) successive application of the finite-element method and the classical Rayleigh-Ritz technique. The finite-element method is first used to generate few global approximation vectors (or modes). Then the amplitudes of these modes are computed by using the Rayleigh-Ritz technique. The proposed technique has high potential for handling practical tire problems with anisotropic materials, unsymmetric imperfections and asymmetric loading. It is also particularly useful for use with three-dimensional finite-element models of tires

    Exploiting symmetries in the modeling and analysis of tires

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    A simple and efficient computational strategy for reducing both the size of a tire model and the cost of the analysis of tires in the presence of symmetry-breaking conditions (unsymmetry in the tire material, geometry, or loading) is presented. The strategy is based on approximating the unsymmetric response of the tire with a linear combination of symmetric and antisymmetric global approximation vectors (or modes). Details are presented for the three main elements of the computational strategy, which include: use of special three-field mixed finite-element models, use of operator splitting, and substantial reduction in the number of degrees of freedom. The proposed computational stategy is applied to three quasi-symmetric problems of tires: linear analysis of anisotropic tires, through use of semianalytic finite elements, nonlinear analysis of anisotropic tires through use of two-dimensional shell finite elements, and nonlinear analysis of orthotropic tires subjected to unsymmetric loading. Three basic types of symmetry (and their combinations) exhibited by the tire response are identified

    Health in Confinement Swine Production

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    Here\u27s a roundup of disease problems in confinement swine production. This article serves as an introduction for more detailed information in future issues
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