3,473 research outputs found

    Artifacts at 4.5 and 8.0 um in Short Wavelength Spectra from the Infrared Space Observatory

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    Spectra from the Short Wavelength Spectrometer (SWS) on ISO exhibit artifacts at 4.5 and 8 um. These artifacts appear in spectra from a recent data release, OLP 10.0, as spurious broad emission features in the spectra of stars earlier than ~F0, such as alpha CMa. Comparison of absolutely calibrated spectra of standard stars to corresponding spectra from the SWS reveals that these artifacts result from an underestimation of the strength of the CO and SiO molecular bands in the spectra of sources used as calibrators by the SWS. Although OLP 10.0 was intended to be the final data release, these findings have led to an additional release addressing this issue, OLP 10.1, which corrects the artifacts.Comment: 14 pages, AASTex, including 5 figures. Accepted by ApJ Letter

    A Cloudy/Xspec Interface

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    We discuss new functionality of the spectral simulation code CLOUDY which allows the user to calculate grids with one or more initial parameters varied and formats the predicted spectra in the standard FITS format. These files can then be imported into the x-ray spectral analysis software XSPEC and used as theoretical models for observations. We present and verify a test case. Finally, we consider a few observations and discuss our results.Comment: 13 pages, 1 table, 4 figures, accepted for publication in PAS

    Increased elastase sensitivity and decreased intramolecular interactions in the more transmissible 501Y.V1 and 501Y.V2 SARS-CoV-2 variants' spike protein-an in silico analysis.

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    Two SARS-CoV-2 variants of concern showing increased transmissibility relative to the Wuhan virus have recently been identified. Although neither variant appears to cause more severe illness nor increased risk of death, the faster spread of the virus is a major threat. Using computational tools, we found that the new SARS-CoV-2 variants may acquire an increased transmissibility by increasing the propensity of its spike protein to expose the receptor binding domain via proteolysis, perhaps by neutrophil elastase and/or via reduced intramolecular interactions that contribute to the stability of the closed conformation of spike protein. This information leads to the identification of potential treatments to avert the imminent threat of these more transmittable SARS-CoV-2 variants

    Computing and Public Organizations

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    This survey of empirical research on computing in government updates a review that appeared ten years earlier in Public Administration Review. It focuses primarily on research related to the management of computing and on differences between public and private sector management of computing because the bulk of the new research and findings are here. The impacts of computing on employment, structure, worklife, decision making, organizational politics and constitutional issues are treated briefly because there is little new research or new findings. The paper concludes that while the use of computers in government at all levels of the federal system has increased greatly over the last decade, research on computing in government has declined precipitously

    INSTITUTIONS AND THE INTERNATIONAL DIFFUSION OF INFORMATION TECHNOLOG

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    The production and use of information technology (IT) in developed countries is wcll established and growing at a rapid pace. Newly industrializing countries are adopting both IT production and use as national goals. Developing countries are beginning to formulate plans to do the same. The institutional role in the international diffusion of IT is not well understood, but it is clear from the literature on innovation that the institutional role is critical. The paper makes four points. First, a traditional and fairly rigorous way of thinking about innovations - the economic perspective deriving from Schumpeter and Hicks - has been shown by studies from economic history and sociology/communications of innovation to be inadequate for explaining the dynamics of innovative change. The missing element is understanding of differential roles played by institutions. Second, among those promoting the need for institutional intervention there has been a debate about whether innovation is primarily supply-pushed or demand-pulled. The answer to the question has important institutional implications. The evidence, again mostly from economic history, shows it to be both, in iterative fashion. Thus institutions can intervene meaningfully on both sides. Third, there are two major forms of institutional intervention: influence and regulation. The possible intervention actions of institutions can be encompassed by a 2 x 2 matrix with supply-push and demand-pull on one dimension and influence and regulation on the other. Finally, if government wants to intervene, there are six classes of roles that might be pursued to affect innovation

    Isomer shift and magnetic moment of the long-lived 1/2+^{+} isomer in 3079^{79}_{30}Zn49_{49}: signature of shape coexistence near 78^{78}Ni

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    Collinear laser spectroscopy has been performed on the 3079^{79}_{30}Zn49_{49} isotope at ISOLDE-CERN. The existence of a long-lived isomer with a few hundred milliseconds half-life was confirmed, and the nuclear spins and moments of the ground and isomeric states in 79^{79}Zn as well as the isomer shift were measured. From the observed hyperfine structures, spins I=9/2I = 9/2 and I=1/2I = 1/2 are firmly assigned to the ground and isomeric states. The magnetic moment ÎŒ\mu (79^{79}Zn) = −-1.1866(10) ÎŒN\mu_{\rm{N}}, confirms the spin-parity 9/2+9/2^{+} with a Îœg9/2−1\nu g_{9/2}^{-1} shell-model configuration, in excellent agreement with the prediction from large scale shell-model theories. The magnetic moment ÎŒ\mu (79m^{79m}Zn) = −-1.0180(12) ÎŒN\mu_{\rm{N}} supports a positive parity for the isomer, with a wave function dominated by a 2h-1p neutron excitation across the N=50N = 50 shell gap. The large isomer shift reveals an increase of the intruder isomer mean square charge radius with respect to that of the ground state: ή⟹rc2⟩79,79m\delta \langle r^{2}_{c}\rangle^{79,79m} = +0.204(6) fm2^{2}, providing first evidence of shape coexistence.Comment: 5 pages, 4 figures, 1 table, Accepeted by Phys. Rev. Lett. (2016

    Spatially Resolved Outflows in a Seyfert Galaxy at z = 2.39

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    We present the first spatially resolved analysis of rest-frame optical and UV imaging and spectroscopy for a lensed galaxy at z = 2.39 hosting a Seyfert active galactic nucleus (AGN). Proximity to a natural guide star has enabled high signal-to-noise VLT SINFONI + adaptive optics observations of rest-frame optical diagnostic emission lines, which exhibit an underlying broad component with FWHM ~ 700 km/s in both the Balmer and forbidden lines. Measured line ratios place the outflow robustly in the region of the ionization diagnostic diagrams associated with AGN. This unique opportunity - combining gravitational lensing, AO guiding, redshift, and AGN activity - allows for a magnified view of two main tracers of the physical conditions and structure of the interstellar medium in a star-forming galaxy hosting a weak AGN at cosmic noon. By analyzing the spatial extent and morphology of the Ly-alpha and dust-corrected H-alpha emission, disentangling the effects of star formation and AGN ionization on each tracer, and comparing the AGN induced mass outflow rate to the host star formation rate, we find that the AGN does not significantly impact the star formation within its host galaxy.Comment: 16 pages, 5 figures, accepted for publication in Ap
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