101,621 research outputs found

    [Review of] John E. Farley. Majority-Minority Relations

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    John E. Farley, who is on the faculty of Southern Illinois University (Edwardsville), says that he has written this book because he is concerned about the deteriorating status of minorities and intergroup relations in the United States. His main objective is to increase awareness of these issues among college students in race relations classes by not only describing but also analyzing and attempting to explain the problems which our society faces

    Parallel imports, innovations and national welfare: The role of the sizes of the income classes and national markets for health care.

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    This paper shows that regardless of any intra-country income differences, parallel imports result in a lower level of health-care innovation but, contrary to popular as well as conventional theoretical wisdom, a lower price in the Third World compared to market-based discrimination. Despite such a lower price, however, parallel imports unambiguously make all buyers in the Third World worse off when intra-country income disparity exists. On the other hand, even discarding the MNC's profit, there will be cases in which the richer country prefers price discrimination as well. That is, in those cases, no countries will have any incentive under the welfare criterion to undo price discrimination, contrary to Richardso

    Nonsingular black holes, wormholes, and de Sitter cores from anisotropic fluids

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    We study Born-Infeld gravity coupled to an anisotropic fluid in a static, spherically symmetric background. The free function characterizing the fluid is selected on the following grounds: i) recovery of the Reissner-Nordstr\"om solution of GR at large distances, ii) fulfillment of classical energy conditions and iii) inclusion of models of nonlinear electrodynamics as particular examples. Four branches of solutions are obtained, depending on the signs of two parameters on the gravity and matter sectors. On each branch, we discuss in detail the modifications on the innermost region of the corresponding solutions, which provides a plethora of configurations, including nonsingular black holes and naked objects, wormholes and de Sitter cores. The regular character of these configurations is discussed according to the completeness of geodesics and the behaviour of curvature scalars.Comment: 15 double column pages; 7 figure

    Computational screening of magnetocaloric alloys

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    An exciting development over the past few decades has been the use of high-throughput computational screening as a means of identifying promising candidate materials for a variety of structural or functional properties. Experimentally, it is often found that the highest-performing materials contain substantial atomic site disorder. These are frequently overlooked in high-throughput computational searches however, due to difficulties in dealing with materials that do not possess simple, well-defined crystallographic unit cells. Here we demonstrate that the screening of magnetocaloric materials with the help of the density functional theory-based magnetic deformation proxy can be extended to systems with atomic site disorder. This is accomplished by thermodynamic averaging of the magnetic deformation for ordered supercells across a solid solution. We show that the highly non-monotonic magnetocaloric properties of the disordered solid solutions Mn(Co1x_{1-x}Fex_x)Ge and (Mn1x_{1-x}Nix_x)CoGe are successfully captured using this method.Comment: Main text: 8 pages, 6 figures. Supplemental Material: 2 pages, 2 figure

    Topological vortices in generalized Born-Infeld-Higgs electrodynamics

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    A consistent BPS formalism to study the existence of topological axially symmetric vortices in generalized versions of the Born-Infeld-Higgs electrodynamics is implemented. Such a generalization modifies the field dynamics via introduction of three non-negative functions depending only in the Higgs field, namely, G(ϕ)G(|\phi|), w(ϕ)w(|\phi|) and V(ϕ)V(|\phi|). A set of first-order differential equations is attained when these functions satisfy a constraint related to the Ampere law. Such a constraint allows to minimize the system energy in such way that it becomes proportional to the magnetic flux. Our results provides an enhancement of topological vortex solutions in Born-Infeld-Higgs electrodynamics. Finally, we analyze a set of models such that a generalized version of Maxwell-Higgs electrodynamics is recovered in a certain limit of the theory.Comment: 8 pages, 8 figures, to appear in EPJ
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