42,787 research outputs found

    High-altitude plume computer code development

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    The flowfield codes that have been developed to predict rocket motor plumes at high altitude were used to predict plume properties for the RCS motor which show reasonable agreement with experimental data. A systematic technique was established for the calculation of high altitude plumes. The communication of data between the computer codes was standardized. It is recommended that these outlined procedures be more completed, documented and updated as the plume methodology is applied to the varied problems of plume flow and plume impingement encountered by space station design and operation

    GRBlog: A Database for Gamma-Ray Bursts

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    GRBlog is an on-line database providing researchers with quick access to all information reported in the GCN Circulars. Users of the GRBlog web site (grad40.as.utexas.edu/grblog.php) can search the circulars and produce afterglow light curve plots, or compile data tables. The site also offers advanced search capabilities to aide in statistical studies or comparative research. Most of the GCNs have already been entered into the GRBlog database, with the remainder to follow shortly.Comment: 4 pages, 2 figures. Proceedings for the 2003 GRB Conference (Santa Fe, NM, 2003 Sep 8-12

    Amenability and co-amenability of algebraic quantum groups

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    We define concepts of amenability and co-amenability for algebraic quantum groups in the sense of A. Van Daele. We show that co-amenability of an algebraic quantum group always implies amenability of its dual. Various necessary and/or sufficient conditions for amenability or co-amenability are obtained. Co-amenability is shown to have interesting consequences for the modular theory in the case that the algebraic quantum group is of compact type.Comment: 25 pages, with some minor corrections, as to appear in the IJMM

    Numerical solutions of the one-dimensional nucleon-meson cascade equations

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    Numerical integration of meson-nucleon cascade equations for accelerator shielding calculation

    Galaxies into the Dark Ages

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    We consider the capabilities of current and future large facilities operating at 2\,mm to 3\,mm wavelength to detect and image the [CII] 158\,μ\mum line from galaxies into the cosmic "dark ages" (z∼10z \sim 10 to 20). The [CII] line may prove to be a powerful tool in determining spectroscopic redshifts, and galaxy dynamics, for the first galaxies. We emphasize that the nature, and even existence, of such extreme redshift galaxies, remains at the frontier of open questions in galaxy formation. In 40\,hr, ALMA has the sensitivity to detect the integrated [CII] line emission from a moderate metallicity, active star-forming galaxy [ZA=0.2 Z⊙Z_A = 0.2\,Z_{\odot}; star formation rate (SFR) = 5\,M⊙M_\odot\,yr−1^{-1}], at z=10z = 10 at a significance of 6σ\sigma. The next-generation Very Large Array (ngVLA) will detect the integrated [CII] line emission from a Milky-Way like star formation rate galaxy (ZA=0.2 Z⊙Z_{A} = 0.2\,Z_{\odot}, SFR = 1\,M⊙M_\odot\,yr−1^{-1}), at z=15z = 15 at a significance of 6σ\sigma. Imaging simulations show that the ngVLA can determine rotation dynamics for active star-forming galaxies at z∼15z \sim 15, if they exist. Based on our very limited knowledge of the extreme redshift Universe, we calculate the count rate in blind, volumetric surveys for [CII] emission at z∼10z \sim 10 to 20. The detection rates in blind surveys will be slow (of order unity per 40\,hr pointing). However, the observations are well suited to commensal searches. We compare [CII] with the [OIII] 88μ\mum line, and other ancillary information in high zz galaxies that would aid these studies.Comment: 11pages, 8 figures, Accepted for the Astrophysical Journa
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