14,985 research outputs found

    The normality of the exception in democracy’s empire

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    The motif is one of inversion. In its received mode, the exception – the exceptional decision suspending the normal legal order – generates both the sovereign and the law. Here, on the contrary, the exception is found to be of the ‘normal’ law and, thus endowed, law goes to constitute the sovereign. This normality of the exception is then matched with the sovereign claim of democracy's empire. That empire is thence shown to have an oxymoronic quality, democracy and its constituent law being conducive to empire yet ultimately opposed to it. The empire of the United States of America provides a ‘case’

    Social Capital and Violence across Racial and Ethnic Samples of Adolescents

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    Using a national sample of adolescents, results of this study demonstrate the important role family and school social capital plays in protecting both White and selected non- White students against violent outcomes. For example, parent-child relationship was associated with reduced violence for Black and White adolescents but not for Hispanics. School affiliation was significant in models for Hispanic and White adolescents but not in models for Black students. Sports participation was associated with greater violence among Hispanics and Whites, but not Blacks. Interestingly, club participation was significant for Whites, but, like sports, it was associated with greater violence. Parental monitoring and religious participation were significant only for Whites while neighbor involvement was significant only for Blacks

    Lessons from crossing symmetry at large N

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    20 pages, v2: Assumptions stated more clearly, version published in JHEPWe consider the four-point correlator of the stress tensor multiplet in N=4 SYM. We construct all solutions consistent with crossing symmetry in the limit of large central charge c ~ N^2 and large g^2 N. While we find an infinite tower of solutions, we argue most of them are suppressed by an extra scale \Delta_{gap} and are consistent with the upper bounds for the scaling dimension of unprotected operators observed in the numerical superconformal bootstrap at large central charge. These solutions organize as a double expansion in 1/c and 1/\Delta_{gap}. Our solutions are valid to leading order in 1/c and to all orders in 1/\Delta_{gap} and reproduce, in particular, instanton corrections previously found. Furthermore, we find a connection between such upper bounds and positivity constraints arising from causality in flat space. Finally, we show that certain relations derived from causality constraints for scattering in AdS follow from crossing symmetry.Peer reviewe

    Two-fluid magnetic island dynamics in slab geometry: I - Isolated islands

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    A set of reduced, 2-D, two-fluid, drift-MHD equations is derived. Using these equations, a complete and fully self-consistent solution is obtained for an isolated magnetic island propagating through a slab plasma with uniform but different ion and electron fluid velocities. The ion and electron fluid flow profiles around the island are uniquely determined, and are everywhere continuous. Moreover, the island phase-velocity is uniquely specified by the condition that there be zero net electromagnetic force acting on the island. Finally, the ion polarization current correction to the Rutherford island width evolution equation is evaluated, and found to be stabilizing provided that the anomalous perpendicular ion viscosity significantly exceeds the anomalous perpendicular electron viscosity

    Hydrodynamic model for expansion and collisional relaxation of x-ray laser-excited multi-component nanoplasma

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    The irradiation of an atomic cluster with a femtosecond x-ray free-electron laser pulse results in a nanoplasma formation. This typically occurs within a few hundreds femtoseconds. By this time the x-ray pulse is over, and the direct photoinduced processes no longer contributing. All created electrons within the nanoplasma are thermalized. The nanoplasma thus formed is a mixture of atoms, electrons and ions of various charges. While expanding, it is undergoing electron impact ionization and three-body recombination. Below we present a hydrodynamic model to describe the dynamics of such multi-component nanoplasma. The model equations are derived by taking the moments of the corresponding Boltzmann kinetic equations. We include the equations obtained, together with the source terms due to electron impact ionization and three-body recombination, in our hydrodynamic solver. Model predictions for a test case: expanding spherical Ar nanoplasma are obtained. With this model we complete the two-step approach to simulate x-ray created nanoplasmas, enabling computationally efficient simulations of their picosecond dynamics. Moreover, the hydrodynamic framework including collisional processes can be easily extended for other source terms and then applied to follow relaxation of any finite non-isothermal multi-component nanoplasma with its components relaxed into local thermodynamic equilibrium.Comment: 12 pages, 4 figures. This article has been accepted by Physics of Plasmas. After it is published, it will be found at http://scitation.aip.org/content/aip/journal/po
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