136,277 research outputs found

    Parameter Compilation

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    In resolving instances of a computational problem, if multiple instances of interest share a feature in common, it may be fruitful to compile this feature into a format that allows for more efficient resolution, even if the compilation is relatively expensive. In this article, we introduce a formal framework for classifying problems according to their compilability. The basic object in our framework is that of a parameterized problem, which here is a language along with a parameterization---a map which provides, for each instance, a so-called parameter on which compilation may be performed. Our framework is positioned within the paradigm of parameterized complexity, and our notions are relatable to established concepts in the theory of parameterized complexity. Indeed, we view our framework as playing a unifying role, integrating together parameterized complexity and compilability theory

    Compilation of Giant Electric Dipole Resonances Built on Excited States

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    Giant Electric Dipole Resonance (GDR) parameters for gamma decay to excited states with finite spin and temperature are compiled. Over 100 original works have been reviewed and from some 70 of which more than 300 parameter sets of hot GDR parameters for different isotopes, excitation energies, and spin regions have been extracted. All parameter sets have been brought onto a common footing by calculating the equivalent Lorentzian parameters. The current compilation is complementary to an earlier compilation by Samuel S. Dietrich and Barry L. Berman (At. Data Nucl. Data Tables 38(1988)199-338) on ground-state photo-neutron and photo-absorption cross sections and their Lorentzian parameters. A comparison of the two may help shed light on the evolution of GDR parameters with temperature and spin. The present compilation is current as of January 2006.Comment: 31 pages including 1 tabl

    Aerothermal modeling, phase 1. Volume 2: Experimental data

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    The experimental test effort is discussed. The test data are presented. The compilation is divided into sets representing each of the 18 experimental configurations tested. A detailed description of each configuration, and plots of the temperature difference ratio parameter or pattern factor parameter calculated from the test data are also provided

    Consumption to biomass (Q/B) ratio and estimates of Q/B-predictor parameters for Caribbean fishes

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    Estimates of the Q/B ratio and parameters of equations to 'predict' Q/B values for 116 fish stocks in the Gulf of Salamanca, Colombia are presented. A compilation of these estimates available for Caribbean Sea fishes (264 stocks) is also provided for comparison purposes. General trends in the value of Q/B resulting from differences in the equation and parameter values used are briefly discussed

    Observational Constraints on Exponential Gravity

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    We study the observational constraints on the exponential gravity model of f(R)=-beta*Rs(1-e^(-R/Rs)). We use the latest observational data including Supernova Cosmology Project (SCP) Union2 compilation, Two-Degree Field Galaxy Redshift Survey (2dFGRS), Sloan Digital Sky Survey Data Release 7 (SDSS DR7) and Seven-Year Wilkinson Microwave Anisotropy Probe (WMAP7) in our analysis. From these observations, we obtain a lower bound on the model parameter beta at 1.27 (95% CL) but no appreciable upper bound. The constraint on the present matter density parameter is 0.245< Omega_m^0<0.311 (95% CL). We also find out the best-fit value of model parameters on several cases.Comment: 14pages, 3 figures, accepted by PR

    Observational constraints on thawing quintessence models

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    We use a dynamical systems approach to study thawing quintessence models, using a multi-parameter extension of the exponential potential which can approximate the form of typical thawing potentials. We impose observational constraints using a compilation of current data, and forecast the tightening of constraints expected from future dark energy surveys, as well as discussing the relation of our results to analytical constraints already in the literature.Comment: 6 pages MNRAS style with 8 figures included. Minor updates to match MNRAS accepted versio

    Constraints on Exotic Matter for An Emergent Universe

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    We study a composition of normal and exotic matter which is required for a flat Emergent Universe scenario permitted by the equation of state (EOS)(p=AρBρ1/2p=A\rho-B\rho^{1/2}) and predict the range of the permissible values for the parameters AA and BB to explore a physically viable cosmological model. The permitted values of the parameters are determined taking into account the H(z)zH(z)-z data obtained from observations, a model independent BAO peak parameter and CMB shift parameter (WMAP7 data). It is found that although AA can be very close to zero, most of the observations favours a small and negative AA. As a consequence, the effective Equation of State parameter for this class of Emergent Universe solutions remains negative always. We also compared the magnitude (μ(z)\mu (z)) vs. redshift(zz) curve obtained in the model with that obtained from the union compilation data. According to our analysis the class of Emergent Universe solutions considered here is not ruled out by the observations.Comment: 6 pages, 7 figures, 1 tabl
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