21,188 research outputs found

    Modeling of turbulent supersonic H2-air combustion with an improved joint beta PDF

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    Attempts at modeling recent experiments of Cheng et al. indicated that discrepancies between theory and experiment can be a result of the form of assumed probability density function (PDF) and/or the turbulence model employed. Improvements in both the form of the assumed PDF and the turbulence model are presented. The results are again used to compare with measurements. Initial comparisons are encouraging

    Representations of swine flu: Perspectives from a Malaysian pig farm

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    © The Author(s), 2010. This is the author's accepted manuscript. The final published article is available from the link below.Novel influenza viruses are seen, internationally, as posing considerable health challenges, but public responses to such viruses are often rooted in cultural representations of disease and risk. However, little research has been conducted in locations associated with the origin of a pandemic. We examined representations and risk perceptions associated with swine flu amongst 120 Malaysian pig farmers. Thirty-seven per cent of respondents felt at particular risk of infection, two-thirds were somewhat or very concerned about being infected. Those respondents who were the most anxious believed particular societal “out-groups” (homosexuals, the homeless and prostitutes) to be at higher infection risk. Although few (4%) reported direct discrimination, 46% claimed friends had avoided them since the swine flu outbreak. Findings are discussed in the context of evolutionary, social representations and terror management theories of response to pandemic threat

    Spectral properties in the charge density wave phase of the half-filled Falicov-Kimball Model

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    We study the spectral properties of charge density wave (CDW) phase of the half-filled spinless Falicov-Kimball model within the framework of the Dynamical Mean Field Theory. We present detailed results for the spectral function in the CDW phase as function of temperature and UU. We show how the proximity of the non-fermi liquid phase affects the CDW phase, and show that there is a region in the phase diagram where we get a CDW phase without a gap in the spectral function. This is a radical deviation from the mean-field prediction where the gap is proportional to the order parameter

    A k-omega-multivariate beta PDF for supersonic combustion

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    In an attempt to study the interaction between combustion and turbulence in supersonic flows, an assumed PDF has been employed. This makes it possible to calculate the time average of the chemical source terms that appear in the species conservation equations. In order to determine the averages indicated in an equation, two transport equations, one for the temperature (enthalpy) variance and one for Q, are required. Model equations are formulated for such quantities. The turbulent time scale controls the evolution. An algebraic model similar to that used by Eklund et al was used in an attempt to predict the recent measurements of Cheng et al. Predictions were satisfactory before ignition but were less satisfactory after ignition. One of the reasons for this behavior is the inadequacy of the algebraic turbulence model employed. Because of this, the objective of this work is to develop a k-omega model to remedy the situation

    Missing energies at pair creation

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    Wilson cloud chamber measurements of the separated spectra of positrons and electrons produced by gamma quanta of 6.14 MeV differ considerably from the theoretically predicted spectra by BETHE and HEITLER, but are in good agreement with those of a modified theory of pair creation

    Social safety net and the poor during the transition : the case of Bulgaria

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    Using data from the 1992 Bulgarian household budget survey, the authors analyze the structure of income in Bulgaria, identifying who the poor are and how they are reached by the social safety net. Their main findings about household incomes: (a) Social transfers provide an extremely large component - 24 percent - of household income per capita. That is roughly on a par with the share in other Eastern European countries but more than 40 percent higher than the share of the Organization for Economic Cooperation and Development (OECD) countries. (b) Wage earnings have declined as a source of income, reflecting the counteraction of the state sector. Wage income in Bulgaria has declined to only half the OECD level. (c) Income from self-employment has increased, reflecting the surge in small-scale retail establishments. Income is considerably less concentrated in Bulgaria than in other lower-middle-income countries. The author's main findings about the poor (the bottom 20 percent in terms of household income): The head of household in a poor home tends to be older, a woman, poorly educated, and unemployed. Poor households are not necessarily larger households in Bulgaria, unlike in other developing countries. The sources of income in poor Bulgarian households reflect other findings: (a) The poor depend for more than half their income on social benefits (especially pensions), indicating the importance of the social safety net. (b) The social safety net is not well targeted. Most social benefits are pro-poor, in the sense that they improve income distribution, but many benefits accrue to better-off households. There is substantial scope for better distribution of income. The authors conclude that comprehensive reform of social benefits is needed, focusing on pensions, unemployment benefits, child allowances, and social assistance.Environmental Economics&Policies,Economic Theory&Research,Labor Policies,Services&Transfers to Poor,Poverty Impact Evaluation,Inequality,Environmental Economics&Policies,Economic Theory&Research,Services&Transfers to Poor,Safety Nets and Transfers

    Optical bistability in sideband output modes induced by squeezed vacuum

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    We consider NN two-level atoms in a ring cavity interacting with a broadband squeezed vacuum centered at frequency ωs\omega_{s} and an input monochromatic driving field at frequency ω\omega . We show that, besides the central mode (at \o), many other {\em sideband modes} are produced at the output, with frequencies shifted from ω\omega by multiples of 2(ωωs) 2(\omega -\omega_{s}). Here we analyze the optical bistability of the two nearest sideband modes, one red-shifted and the other blue-shifted.Comment: Replaced with final published versio
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