894 research outputs found

    Further restrictions on the topology of stationary black holes in five dimensions

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    We place further restriction on the possible topology of stationary asymptotically flat vacuum black holes in 5 spacetime dimensions. We prove that the horizon manifold can be either a connected sum of Lens spaces and "handles" S1×S2S^1 \times S^2, or the quotient of S3S^3 by certain finite groups of isometries (with no "handles"). The resulting horizon topologies include Prism manifolds and quotients of the Poincare homology sphere. We also show that the topology of the domain of outer communication is a cartesian product of the time direction with a finite connected sum of R4,S2×S2\mathbb R^4,S^2 \times S^2's and CP2CP^2's, minus the black hole itself. We do not assume the existence of any Killing vector beside the asymptotically timelike one required by definition for stationarity.Comment: LaTex, 22 pages, 9 figure

    Supersymmetric Field-Theoretic Models on a Supermanifold

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    We propose the extension of some structural aspects that have successfully been applied in the development of the theory of quantum fields propagating on a general spacetime manifold so as to include superfield models on a supermanifold. We only deal with the limited class of supermanifolds which admit the existence of a smooth body manifold structure. Our considerations are based on the Catenacci-Reina-Teofillatto-Bryant approach to supermanifolds. In particular, we show that the class of supermanifolds constructed by Bonora-Pasti-Tonin satisfies the criterions which guarantee that a supermanifold admits a Hausdorff body manifold. This construction is the closest to the physicist's intuitive view of superspace as a manifold with some anticommuting coordinates, where the odd sector is topologically trivial. The paper also contains a new construction of superdistributions and useful results on the wavefront set of such objects. Moreover, a generalization of the spectral condition is formulated using the notion of the wavefront set of superdistributions, which is equivalent to the requirement that all of the component fields satisfy, on the body manifold, a microlocal spectral condition proposed by Brunetti-Fredenhagen-K\"ohler.Comment: Final version to appear in J.Math.Phy

    The effect of nicotine dependence and withdrawal symptoms on use of nicotine replacement therapy: Secondary analysis of a randomized controlled trial in primary care

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    INTRODUCTION: Nicotine replacement therapy (NRT) is effective for smoking cessation, but the optimal method of using NRT to maximize benefit is unclear. We examined whether nicotine dependence was associated with consumption of NRT, whether this was mediated by withdrawal symptoms, and the impact of these factors on cessation, in a population advised to use as much NRT as needed. METHODS: Secondary analysis of data from an open label, parallel group randomized controlled trial. Participants (n = 539) attended a smoking cessation clinic in primary care and remained engaged with treatment for at least one week following a quit attempt. Baseline dependence was measured by the Fagerström Test for Cigarette Dependence (FTCD), with tobacco exposure assessed via an exhaled carbon monoxide test. At one week after quit day, mean daily consumption of NRT was measured for all participants; withdrawal (Mood and Physical Symptoms Scale (MPSS)) was also assessed in the subsample who reported being completely abstinent to that point (n = 279). Abstinence was biochemically assessed at four weeks for all participants as the principal smoking cessation outcome. RESULTS: Each point higher on the FTCD was associated with 0.83 mg/day more NRT consumption, controlling for tobacco exposure. This relationship was diminished when withdrawal was controlled for, and withdrawal was associated with NRT consumption, with each point higher on the MPSS associated with a 0.12 mg/day increase. Increased consumption of NRT directly predicted subsequent smoking cessation. CONCLUSIONS: Higher dependence appears to lead to greater withdrawal, which appears to drive greater use of NRT. This effect may partly offset lower abstinence rates in people with higher dependence. Advice to use sufficient NRT to suppress withdrawal may increase abstinence rates

    Asymptotic structure of radiation in higher dimensions

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    We characterize a general gravitational field near conformal infinity (null, spacelike, or timelike) in spacetimes of any dimension. This is based on an explicit evaluation of the dependence of the radiative component of the Weyl tensor on the null direction from which infinity is approached. The behaviour similar to peeling property is recovered, and it is shown that the directional structure of radiation has a universal character that is determined by the algebraic type of the spacetime. This is a natural generalization of analogous results obtained previously in the four-dimensional case.Comment: 14 pages, no figures (two references added

    On leading order gravitational backreactions in de Sitter spacetime

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    Backreactions are considered in a de Sitter spacetime whose cosmological constant is generated by the potential of scalar field. The leading order gravitational effect of nonlinear matter fluctuations is analyzed and it is found that the initial value problem for the perturbed Einstein equations possesses linearization instabilities. We show that these linearization instabilities can be avoided by assuming strict de Sitter invariance of the quantum states of the linearized fluctuations. We furthermore show that quantum anomalies do not block the invariance requirement. This invariance constraint applies to the entire spectrum of states, from the vacuum to the excited states (should they exist), and is in that sense much stronger than the usual Poincare invariance requirement of the Minkowski vacuum alone. Thus to leading order in their effect on the gravitational field, the quantum states of the matter and metric fluctuations must be de Sitter invariant.Comment: 12 pages, no figures, typos corrected and some clarifying comments added, version accepted by Phys. Rev.

    Mass, Angular Momentum and Thermodynamics in Four-Dimensional Kerr-AdS Black Holes

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    In this paper, the connection between the Lorentz-covariant counterterms that regularize the four-dimensional AdS gravity action and topological invariants is explored. It is shown that demanding the spacetime to have a negative constant curvature in the asymptotic region permits the explicit construction of such series of boundary terms. The orthonormal frame is adapted to appropriately describe the boundary geometry and, as a result, the boundary term can be expressed as a functional of the boundary metric, extrinsic curvature and intrinsic curvature. This choice also allows to write down the background-independent Noether charges associated to asymptotic symmetries in standard tensorial formalism. The absence of the Gibbons-Hawking term is a consequence of an action principle based on a boundary condition different than Dirichlet on the metric. This argument makes plausible the idea of regarding this approach as an alternative regularization scheme for AdS gravity in all even dimensions, different than the standard counterterms prescription. As an illustration of the finiteness of the charges and the Euclidean action in this framework, the conserved quantities and black hole entropy for four-dimensional Kerr-AdS are computed.Comment: 15 pages,no figures,few references added,JHEP forma

    Vortex Counting and Lagrangian 3-manifolds

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    To every 3-manifold M one can associate a two-dimensional N=(2,2) supersymmetric field theory by compactifying five-dimensional N=2 super-Yang-Mills theory on M. This system naturally appears in the study of half-BPS surface operators in four-dimensional N=2 gauge theories on one hand, and in the geometric approach to knot homologies, on the other. We study the relation between vortex counting in such two-dimensional N=(2,2) supersymmetric field theories and the refined BPS invariants of the dual geometries. In certain cases, this counting can be also mapped to the computation of degenerate conformal blocks in two-dimensional CFT's. Degenerate limits of vertex operators in CFT receive a simple interpretation via geometric transitions in BPS counting.Comment: 70 pages, 29 figure

    Information-based cues at point of choice to change selection and consumption of food, alcohol and tobacco products: a systematic review

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    Background: Reducing harmful consumption of food, alcohol, and tobacco products would prevent many cancers, diabetes and cardiovascular disease. Placing information-based cues in the environments in which we select and consume these products has the potential to contribute to changing these behaviours. Methods: In this review, information-based cues are defined as those which comprise any combination of words, symbols, numbers or pictures that convey information about a product or its use. We specifically exclude cues which are located on the products themselves. We conducted a systematic review of randomised, cluster- randomised, and non-randomised controlled trials to assess the impact of such cues on selection and consumption. Thirteen studies met the inclusion criteria, of which 12 targeted food (most commonly fruit and vegetables), one targeted alcohol sales, and none targeted tobacco products. Results: Ten studies reported statistically significant effects on some or all of the targeted products, although studies were insufficiently homogenous to justify meta-analysis. Existing evidence suggests information-based cues can influence selection and consumption of food and alcohol products, although significant uncertainty remains. Conclusions: The current evidence base is limited both in quality and quantity, with relatively few, heterogeneous studies at unclear or high risk of bias. Additional, more rigorously conducted studies are warranted to better estimate the potential for these interventions to change selection and consumption of food, alcohol and tobacco products. Trial registration: PROSPERO. 2016;CRD42016051884
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