3,108 research outputs found

    Elliptic flow due to radiation in heavy-ion collisions

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    In this paper we demonstrate that radiation patterns could cause flow-like behaviour without any reference to hydrodynamic description. For that purpose we use a statistical ensemble of radiating dipoles, motivated by the investigation of the equivalent photon yield produced by decelerating charges. For the elliptic asymmetry factor we find a reasonable agreement with experimental data.Comment: 5 pages, 5 figures, v2: discussion on the physical interpretation of the form factor F is adde

    Z2 monopoles in D=2+1 SU(2) lattice gauge theory

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    We calculate the Euclidean action of a pair of Z2 monopoles (instantons), as a function of their spatial separation, in D=2+1 SU(2) lattice gauge theory. We do so both above and below the deconfining transition at T=Tc. At high T, and at large separation, we find that the monopole `interaction' grows linearly with distance: the flux between the monopoles forms a flux tube (exactly like a finite portion of a Z2 domain wall) so that the monopoles are linearly confined. At short distances the interaction is well described by a Coulomb interaction with, at most, a very small screening mass, possibly equal to the Debye electric screening mass. At low T the interaction can be described by a simple screened Coulomb (i.e. Yukawa) interaction with a screening mass that can be interpreted as the mass of a `constituent gluon'. None of this is unexpected, but it helps to resolve some apparent controversies in the recent literature.Comment: 14 pages, 2 figure

    Vortices and confinement in hot and cold D=2+1 gauge theories

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    We calculate the variation with temperature of the vortex free energy in D=2+1 SU(2) lattice gauge theories. We do so both above and below the deconfining transition at T=Tc. We find that this quantity is zero at all T for large enough volumes. For T<Tc this observation is consistent with the fact that the phase is linearly confining; while for T>Tc it is consistent with the conventional expectation of `spatial' linear confinement. In small spatial volumes this quantity is shown to be non-zero. The way it decreases to zero with increasing volume is shown to be controlled by the (spatial) string tension and it has the functional form one would expect if the vortices being studied were responsible for the confinement at low T, and for the `spatial' confinement at large T. We also discuss in detail some of the direct numerical evidence for a non-zero spatial string tension at high T, and we show that the observed linearity of the (spatial) potential extends over distances that are large compared to typical high-T length scales.Comment: 27 pages, 6 figure

    The impact of heat waves and cold spells on mortality rates in the Dutch population.

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    We conducted the study described in this paper to investigate the impact of ambient temperature on mortality in the Netherlands during 1979-1997, the impact of heat waves and cold spells on mortality in particular, and the possibility of any heat wave- or cold spell-induced forward displacement of mortality. We found a V-like relationship between mortality and temperature, with an optimum temperature value (e.g., average temperature with lowest mortality rate) of 16.5 degrees C for total mortality, cardiovascular mortality, respiratory mortality, and mortality among those [Greater and equal to] 65 year of age. For mortality due to malignant neoplasms and mortality in the youngest age group, the optimum temperatures were 15.5 degrees C and 14.5 degrees C, respectively. For temperatures above the optimum, mortality increased by 0.47, 1.86, 12.82, and 2.72% for malignant neoplasms, cardiovascular disease, respiratory diseases, and total mortality, respectively, for each degree Celsius increase above the optimum in the preceding month. For temperatures below the optimum, mortality increased 0.22, 1.69, 5.15, and 1.37%, respectively, for each degree Celsius decrease below the optimum in the preceding month. Mortality increased significantly during all of the heat waves studied, and the elderly were most effected by extreme heat. The heat waves led to increases in mortality due to all of the selected causes, especially respiratory mortality. Average total excess mortality during the heat waves studied was 12.1%, or 39.8 deaths/day. The average excess mortality during the cold spells was 12.8% or 46.6 deaths/day, which was mostly attributable to the increase in cardiovascular mortality and mortality among the elderly. The results concerning the forward displacement of deaths due to heat waves were not conclusive. We found no cold-induced forward displacement of deaths

    Assessing for Social and Economic Inequities in Vocational Rehabilitation Services among Individuals with Intellectual and Developmental Disabilities

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    Individuals with intellectual and developmental disabilities (IDD) face disparities in employment. Vocational Rehabilitation (VR) agencies in every U.S. state offer services intended to improve employment outcomes for people with disabilities. Yet, institutionalized supports such as VR services may inadvertently perpetuate social inequities as a result of biases in implementation and/or barriers to access due to an individual’s race, ethnicity, gender identity, sexual orientation, and disability. Additionally, factors associated with economic stability (socioeconomic factors) can also perpetuate inequities in interventions and institutional supports. The goal of this dissertation research is to understand the role of social and economic factors within state VR services for individuals with IDD. This dissertation used a cross-sectional secondary analysis of the RSA-911 dataset of applicants for VR services to 1) assess for social inequities in service provision and economic outcomes among VR service users; 2) assess for social and economic inequities between applicants who did and did not receive services; and 3) explore the relationship between factors associated with economic stability factors among applicants for VR services. Results indicated: 1) social inequities exist in both if applicants received VR services and what services they received from their VR agency; 2) interaction terms between severity of disability and demographic characteristics revealed differences in outcomes for demographic identities at different levels of severity of disability; 3) outcomes varied, based on amount of wage earned and level of education; and 4) a complex relationship exists between level of education, wage earned, and receipt of Social Security benefits should be considered in research and interventions that aim to improve economic stability in people with IDD. Considerations for future research and practice are presented for each main finding

    Information and strategic voting

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    We theoretically and experimentally study voter behavior in a setting characterized by plurality rule and mandatory voting. Voters choose from three options. We are interested in the occurrence of strategic voting in an environment where Condorcet cycles may occur and focus on how information about the preference distribution affects strategic behavior. We also vary the relative importance of the second preferred option. Quantal response equilibrium analysis is used to analyze the game and derive predictions. Our results indeed show that strategic voting arises. Its extent depends on (i) information availability; (ii) the relative importance of the intermediate candidate; (iii) the electorate’s relative support for one’s preferred candidate; (iv) the relative position of the plurality-supported candidate in one’s preference ordering. Our results show that information serves as a coordination device where strategic voting does not harm the plurality-preferred candidate’s chances of winning
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