521 research outputs found
Metrics Admitting Killing Spinors In Five Dimensions
BPS black hole configurations which break half of supersymmetry in the theory
of N=2, d=5 supergravity coupled to an arbitrary number of abelian vector
multiplets are discussed. A general class of solutions comprising all known BPS
rotating black hole solutions is obtained.Comment: 15 pages, Late
D=7 SU(2) Gauged Supergravity From D=10 Supergravity
The theory of SU(2) gauged seven-dimensional supergravity is obtained by
compactifying ten dimensional N=1 supergravity on the group manifold SU(2).Comment: 10 pages. References added and some comments modifie
E-textbooks and connectivity: proposing an analytical framework
This paper is concerned with the development of e-textbooks. We claim that analysis (and design) of e-textbooks requires the development of a specific frame. Digital affordances provide particular opportunities (e.g. in terms of interactions between users) that require specific considerations for their analysis, as teachers and students use them for their individual and collective purposes. In this study, we develop a framework for mathematics e-textbook analysis, based on the notion of “connectivity.” We introduce criteria to assess the different aspects of connectivity and build an analysis grid for e-textbooks. We illustrate the framework proposed by analyzing 2 commonly used French grade 10 mathematics e-textbooks. The results of the analyses show that there are major differences between the 2 e-textbooks in terms of connectivity, which can be related to differences in their design. Beyond these 2 examples, we claim that focusing on connectivity is a useful and relevant way of analyzing e-textbooks, as it can provide a window into issues of interactivity, both practically and cognitively
FAKTOR-FAKTOR YANG MEMPENGARUHI AUDITOR SWITCHING SECARA VOLUNTARY PADA PERUSAHAAN MANUFAKTUR YANG TERDAFTAR PAD BURSA EFEK INDONESIA
This study aims to determine the effect of management change, audit opinion, client size and financial distress on voluntary auditor switching at manufacturing companies listed on the Indonesia Stock Exchange for the period 2010-2014. The population in this study are all manufacturing companies listed on the Indonesia Stock Exchange. The number of manufacturing companies that were sampled using the purposive sampling method was 64 companies for 5 years of observation. Hypothesis testing in this study uses logistic regression analysis. Based on the results of the logistic regression test, the results of this study indicate that the independent variable management change, audit opinion, client size and financial distress have a negative effect on the dependent variable auditor switching voluntarily
Interpolating from AdS_(D-2) X S^2 to AdS_D
We investigate a large class of supersymmetric magnetic brane solutions
supported by U(1) gauge fields in AdS gauged supergravities. We obtain
first-order equations in terms of a superpotential. In particular, we find
systems which interpolate between AdS_{D-2}\times \Omega^2 (where \Omega^2=S^2
or H^2) in the horizon and AdS_D-type geometry in the asymptotic region, for
4\le D\le 7. The boundary geometry of the AdS_D-type metric is
Minkowski_{D-3}\times \Omega^2. This provides smooth supergravity solutions for
which the boundary of the AdS spacetime compactifies spontaneously. These
solutions indicate the existence of a large class of superconformal field
theories in diverse dimensions whose renormalization group flow runs from the
UV to the IR fixed point. We show that the same set of first-order equations
also admits solutions which are asymptotically AdS_{D-2}\times \Omega^2 but
singular at small distance. This implies that the stationary AdS_{D-2}\times
\Omega^2 solutions typically lie on the inflection points of the modulus space.Comment: Latex three times, 49 pages, 9 figure
From AdS Black Holes to Supersymmetric Flux-branes
We show that AdS black hole solutions admit an analytical continuation to
become magnetic flux-branes. Although a BPS AdS black hole generally has a
naked singularity, the BPS flux-brane can be regular everywhere with an
appropriate choice of U(1)-charges. This flux-brane interpolates from AdS_{D-2}
\times H^2 at small distance to an asymptotic AdS_D-type metric with an
AdS_{D-2}\times S^1 boundary. We also obtain a smooth cosmological solution of
de Sitter Einstein-Maxwell gravity which flows from dS_2\times S^{D-2} in the
infinite past to a dS_D-type metric, with an S^{D-2}\times S^1 boundary, in the
infinite future.Comment: Plain latex, 25 pages, references adde
Polarization Diagnostics for Cool Core Cluster Emission Lines
The nature of the interaction between low-excitation gas filaments at ~104 K, seen in optical line emission, and diffuse X-ray emitting coronal gas at ~107 K in the centers of galaxy clusters remains a puzzle. The presence of a strong, empirical correlation between the two gas phases is indicative of a fundamental relationship between them, though as yet of undetermined cause. The cooler filaments, originally thought to have condensed from the hot gas, could also arise from a merger or the disturbance of cool circumnuclear gas by nuclear activity. Here, we have searched for intrinsic line emission polarization in cool core galaxy clusters as a diagnostic of fundamental transport processes. Drawing on developments in solar astrophysics, direct energetic particle impact induced polarization holds the promise to definitively determine the role of collisional processes such as thermal conduction in the ISM physics of galaxy clusters, while providing insight into other highly anisotropic excitation mechanisms such as shocks, intense radiation fields, and suprathermal particles. Under certain physical conditions, theoretical calculations predict of the order of 10% polarization. Our observations of the filaments in four nearby cool core clusters place stringent upper limits ( 0.1%) on the presence of emission line polarization, requiring that if thermal conduction is operative, the thermal gradients are not in the saturated regime. This limit is consistent with theoretical models of the thermal structure of filament interfacesPeer reviewe
Solutions of Minimal Four Dimensional de Sitter Supergravity
Pseudo-supersymmetric solutions of minimal , de Sitter
supergravity are classified using spinorial geometry techniques. We find three
classes of solutions. The first class of solution consists of geometries which
are fibrations over a 3-dimensional manifold equipped with a Gauduchon-Tod
structure. The second class of solution is the cosmological Majumdar-Papapetrou
solution of Kastor and Traschen, and the third corresponds to gravitational
waves propagating in the Nariai cosmology.Comment: 17 Pages. Minor correction to section 4; equation (4.21) corrected
and (old) equation (4.26) deleted; the final result is unchange
Noncommutative Gravity in two Dimensions
We deform two-dimensional topological gravity by making use of its gauge
theory formulation. The obtained noncommutative gravity model is shown to be
invariant under a class of transformations that reduce to standard
diffeomorphisms once the noncommutativity parameter is set to zero. Some
solutions of the deformed model, like fuzzy AdS_2, are obtained. Furthermore,
the transformation properties of the model under the Seiberg-Witten map are
studied.Comment: 20 pages, LaTeX, references and some comments adde
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