202,178 research outputs found

    The ωNN\omega NN couplings derived from QCD sum rules

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    The light cone QCD sum rules are derived for ωNN\omega NN vector and tensor couplings simultaneously. The vacuum gluon field contribution is taken into account. Our results are gω=(18±8),κω=(0.8±0.4)g_\omega =(18\pm 8), \kappa_\omega=(0.8\pm 0.4).Comment: To appear in Phys. Rev. C (Brief Report

    On the study of four-parallelogram filter banks

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    The most commonly used 2-D filter banks are separable filter banks, which can be obtained by cascading two 1-D filter banks in the form of a tree. The supports of the analysis and synthesis filters in the separable systems are unions of four rectangles. The natural nonseparable generalization of such supports are those that are unions of four parallelograms. We study four parallelogram filter banks, which is the class of 2-D filter banks in which the supports of the analysis and synthesis filters consist of four parallelograms. For a given a decimation matrix, there could be more than one possible configuration (the collection of passbands of the analysis filters). Various types of configuration are constructed for four-parallelogram filter banks. Conditions on the configurations are derived such that good design of analysis and synthesis filters are possible. We see that there is only one category of these filter banks. The configurations of four-parallelogram filter banks in this category can always be achieved by designing filter banks of low design cost

    Particle acceleration by the sun

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    A review is given of the analysis of new observations of energetic particles and energetic secondary emissions obtained over the solar maxium (approx. 1980) by the Solar Maximum mission, Hinotori, the international Sun-Earth Explorer, Helios, Explorer satellites, and Voyager spacecraft. Solar energetic particle events observed in space, He(3)- rich events, solar gamma rays and neutrons, and solar neutrinos are discussed

    The heating of the thermal plasma with energetic electrons in small solar flares

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    The energetic electrons deduced from hard X-rays in the thick target model may be responsible for heating of soft X-ray plasma in solar flares. It is shown from OSO-7 studies that if a cutoff of 10 keV is assumed, the total electron is comparable to the thermal plasma energy. However, (1) the soft X-ray emission often appears to begin before the hard X-ray burst, (2) in about one-third of flares there is no detectable hard X-ray emission, and (3) for most events the energy content (assuming constant density) of soft X-ray plasma continues to rise after the end of the hard X-ray burst. To understand these problems we have analyzed the temporal relationship between soft X-rays and hard X-rays for 20 small events observed by ISEE-3 during 1980. One example is shown. The start of soft X-ray and hard X-ray bursts is defined as the time when the counting rates of the 4.8 to 5. keV and 25.8 to 43.2 keV channels, respectively, exceed the background by one standard deviation

    LIFE3: A predictive costing tool for digital collections

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    Predicting the costs of long-term digital preservation is a crucial yet complex task for even the largest repositories and institutions. For smaller projects and individual researchers faced with preservation requirements, the problem is even more overwhelming, as they lack the accumulated experience of the former. Yet being able to estimate future preservation costs is vital to answering a range of important questions for each. The LIFE (Life Cycle Information for E-Literature) project, which has just completed its third phase, helps institutions and researchers address these concerns, reducing the financial and preservation risks, and allowing decision makers to assess a range of options in order to achieve effective preservation while operating within financial restraints. The project is a collaboration between University College London (UCL), The British Library and the Humanities Advanced Technology and Information Institute (HATII) at the University of Glasgow. Funding has been supplied in the UK by the Joint Information Systems Committee (JISC) and the Research Information Network (RIN)

    Nonuniversal Effects in the Homogeneous Bose Gas

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    Effective field theory predicts that the leading nonuniversal effects in the homogeneous Bose gas arise from the effective range for S-wave scattering and from an effective three-body contact interaction. We calculate the leading nonuniversal contributions to the energy density and condensate fraction and compare the predictions with results from diffusion Monte Carlo calculations by Giorgini, Boronat, and Casulleras. We give a crude determination of the strength of the three-body contact interaction for various model potentials. Accurate determinations could be obtained from diffusion Monte Carlo calculations of the energy density with higher statistics.Comment: 24 pages, RevTex, 5 ps figures, included with epsf.te

    New results on multidimensional Chinese remainder theorem

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    The Chinese remainder theorem (CRT) [McClellan and Rader 1979] has been well known for applications in fast DFT computations and computer arithmetic. Guessoum and Mersereau [1986] first made headway in extending the CRT to multidimensional (MD) nonseparable systems and showing its usefulness. The present letter generalize the result and present a more general form. This more general MDCRT is an exact counterpart of 1DCRT
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