1,090 research outputs found

    Local party members’ views are associated, but not completely congruent, with local constituency opinion

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    Do local political party members reflect the views of voters in their constituencies? Since candidate selection by local party members is the most common form of candidate selection in the United Kingdom, it is important to understand local party members’ views, and how those views relate to views in the local area. We investigate the degree to which individual members’ views match local opinion by combining the results of a large-scale survey of party members in the United Kingdom with estimates of local opinion created using multilevel regression and post-stratification. We find that individual party members’ views are moderately to strongly associated with local opinion on both left-right and liberty-authority dimensions. Even so, party members are not entirely congruent with opinion in the local area, having opinions which are either to the left or right of voters in their local area, and which are uniformly more liberal than party supporters

    Do naked singularities generically occur in generalized theories of gravity?

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    A new mechanism for causing naked singularities is found in an effective superstring theory. We investigate the gravitational collapse in a spherically symmetric Einstein-Maxwell-dilaton system in the presence of a pure cosmological constant "potential", where the system has no static black hole solution. We show that once gravitational collapse occurs in the system, naked singularities necessarily appear in the sense that the field equations break down in the domain of outer communications. This suggests that in generalized theories of gravity, the non-minimally coupled fields generically cause naked singularities in the process of gravitational collapse if the system has no static or stationary black hole solution.Comment: 4 pages including 2 eps figures, to be published in Physical Review Letter

    Rotating Solution of Einstein-Maxwell Dilaton Gravity with Unusual Asymptotics

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    We study electrically charged, dilaton black holes, which possess infinitesimal angular momentum in the presence of one or two Liouville type potentials. These solutions are neither asymptotically flat nor (anti)-de Sitter. Some properties of the solutions are discussed.Comment: 11 pages, Accepted (Int. J. Theor. Phys.

    Charged Dilaton Black Holes with a Cosmological Constant

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    The properties of static spherically symmetric black holes, which are either electrically or magnetically charged, and which are coupled to the dilaton in the presence of a cosmological constant, are considered. It is shown that such solutions do not exist if the cosmological constant is positive (in arbitrary spacetime dimension >= 4). However, asymptotically anti-de Sitter black hole solutions with a single horizon do exist if the cosmological constant is negative. These solutions are studied numerically in four dimensions and the thermodynamic properties of the solutions are derived. The extreme solutions are found to have zero entropy and infinite temperature for all non-zero values of the dilaton coupling constant.Comment: 12 pages, epsf, phyzzx, 4 in-text figures incl. (minor typos fixed, 1 reference added

    New hairy black hole solutions with a dilaton potential

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    We consider black hole solutions with a dilaton field possessing a nontrivial potential approaching a constant negative value at infinity. The asymptotic behaviour of the dilaton field is assumed to be slower than that of a localized distribution of matter. A nonabelian SU(2) gauge field is also included in the total action. The mass of the solutions admitting a power series expansion in 1/r1/r at infinity and preserving the asymptotic anti-de Sitter geometry is computed by using a counterterm subtraction method. Numerical arguments are presented for the existence of hairy black hole solutions for a dilaton potential of the form V(ϕ)=C1exp(2α1ϕ)+C2exp(2α2ϕ)+C3V(\phi)=C_1 \exp(2\alpha_1 \phi)+C_2 \exp(2\alpha_2 \phi)+C_3, special attention being paid to the case of N=4,D=4{\cal N}=4, D=4 gauged supergravity model of Gates and Zwiebach.Comment: 12 pages, 4 figures; v2:references added, typos corrected, small changes in Section

    Charged Nariai Black Holes With a Dilaton

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    The Reissner-Nordstrom-de Sitter black holes of standard Einstein-Maxwell theory with a cosmological constant have no analogue in dilatonic theories with a Liouville potential. The only exception are the solutions of maximal mass, the Charged Nariai solutions. We show that the structure of the solution space of the Dilatonic Charged Nariai black holes is quite different from the non-dilatonic case. Its dimensionality depends on the exponential coupling constants of the dilaton. We discuss the possibility of pair creating such black holes on a suitable background. We find conditions for the existence of Charged Nariai solutions in theories with general dilaton potentials, and consider specifically a massive dilaton.Comment: 20 pages, LaTeX, 4 figures, submitted to Phys. Rev.

    Prospective study of 310 patients: can early CT predict the severity of acute pancreatitis?

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    Background: This study was designed to determine the most important early CT parameters predictive of acute pancreatitis severity. Methods: Three hundred and seventy-one consecutive patients with acute abdominal pain and hyperamylasemia were enrolled. Three hundred and ten of the 371 patients met our inclusion criteria. Acute pancreatitis severity was evaluated using the 1992 Atlanta criteria. Different CT parameters were reported from the admission abdominal CT by two radiologists blinded from any clinical parameter, but the patients' age and gender. These variables were fitted in a binary logistic regression model. Results: Acute pancreatitis was mild in 80% cases, severe in 20% cases and lethal in 12.69% cases. The following CT parameters were significantly associated with the severity of acute pancreatitis: the objective size of the pancreas (P=0.001), the peripancreatic fat abnormalities (P=0.001) and the extent of necrosis (P=0.007). Moreover, the age of the patient revealed itself a highly significant (P=0.001) indicator of disease severity. The association of the four CT criteria eventually showed a sensitivity of 73% and a specificity of 81% to predict acute pancreatitis severity. Conclusion: Although these criteria correlated with disease severity, our study identified that morphological CT criteria cannot be used to triage patients with severe and mild acute pancreatiti

    Kinetic Monte Carlo approach to nonequilibrium bosonic systems

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    We consider the use of a kinetic Monte Carlo approach for the description of nonequilibrium bosonic systems, taking nonresonantly excited exciton-polariton condensates and bosonic cascade lasers as examples. In the former case, the considered approach allows the study of the cross-over between incoherent and coherent regimes, which represents the formation of a quasicondensate that forms purely from the action of energy relaxation processes rather than interactions between the condensing particles themselves. In the latter case, we show theoretically that a bosonic cascade can develop an output coherent state

    Advances and limitations in the modelling of fabricated photonic bandgap fibers

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    Copyright © 2006 IEEEWe model fabricated silica photonic bandgap fibers and achieve good agreement between simulated and measured properties. We identify the size of the SEM bitmap image as the ultimate limit to the accurate calculation of surfaces modes within the bandgapF. Poletti, M. N. Petrovich, R. Amezcua-Correa, N. G. Broderick, T. M. Monro and D. J. Richardsonhttp://eprints.soton.ac.uk/47883
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