21,159 research outputs found

    A Relation Between N=8 Gauge Theories in Three Dimensions

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    We show that three-dimensional N=8 Sp(N)Sp(N) and SO(2N+1)SO(2N+1) gauge theories flow to the same strong coupling fixed point. As a consequence, the corresponding orientifold two-planes in type IIA string theory are described at strong coupling and low-energies by the same M theory background. In the large NN limit, these assertions are confirmed by studying discrete torsion in the supergravity theory corresponding to membranes on R8/Z2R^8/Z_2.Comment: 8 pages, harvmac; an acknowledgement adde

    Supersymmetry Breaking by Fluxes

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    Type II string theory and M-theory admit flux configurations that break supersymmetry below the Kaluza-Klein scale. These backgrounds play a central role in most models of the string landscape. I argue that the behavior of such backgrounds at weak coupling is generically a rolling solution, not a static space-time. Quantum corrections to the space-time potential are computed around this classical time-dependent background. This is particularly important for non-perturbative corrections. This change in perspective offers an explanation for why there appear to be many effective field theory models that seemingly evade the known no-go theorems forbidding de Sitter space-times. This has interesting implications for type IIB string landscape models.Comment: 31 pages; LaTeX; references added; minor changes and more references adde

    The promotion of data sharing in pharmacoepidemiology

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    This article addresses the role of pharmacoepidemiology in patient safety and the crucial role of data sharing in ensuring that such activities occur. Against the backdrop of proposed reforms of European data protection legislation, it considers whether the current legislative landscape adequately facilitates this essential data sharing. It is argued that rather than maximising and promoting the benefits of such activities by facilitating data sharing, current and proposed legislative landscapes hamper these vital activities. The article posits that current and proposed data protection approaches to pharmacoepidemiology — and more broadly, re-uses of data — should be reoriented towards enabling these important safety enhancing activities. Two potential solutions are offered: 1) a dedicated working party on data reuse for health research and 2) the introduction of new, dedicated legislation

    Domain Walls, Triples and Acceleration

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    We present a construction of domain walls in string theory. The domain walls can bridge both Minkowski and AdS string vacua. A key ingredient in the construction are novel classical Yang-Mills configurations, including instantons, which interpolate between toroidal Yang-Mills vacua. Our construction provides a concrete framework for the study of inflating metrics in string theory. In some cases, the accelerating space-time comes with a holographic description. The general form of the holographic dual is a field theory with parameters that vary over space-time.Comment: 63 pages, 1 figure; LaTe

    Stability of Equilibria in Games with Procedurally Rational Players

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    One approach to the modeling of bounded rationality in strategic environments is based on the dynamics of evolution and learning in games. An entirely different approach has been developed recently by Osborne and Rubinstein (1998). This latter approach is static and equilibrium based, but relies on less stringent assumptions regarding the knowledge and understanding of players than does the standard theory of Nash equilibrium. This paper formalizes Osborne and Rubinstein's dynamic interpretation of their equilibrium concept and thereby facilitates a comparison of this approach with the explicitly dynamic approach of evolutionary game theory. It turns out that the two approaches give rise to radically different static and dynamic predictions. For instance, dynamically stable equilibria can involve the playing of strictly dominated actions, and equilibria in which strictly actions are played with probability 1 can be unstable. Sufficient conditions for the instability of equilibria are provided for symmetric and asymmetric games.Dynamic Stability, S(1) Equilibrium, Procedural Rationality, Evolutionary Games
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