On the existence of a static black hole on a brane

We study a static black hole localized on a brane in the Randall-Sundrum (RS) II braneworld scenario. To solve this problem numerically, we develop a code having the almost 4th-order accuracy. This code derives the highly accurate result for the case where the brane tension is zero, i.e., the spherically symmetric case. However, a nonsystematic error is detected in the cases where the brane tension is nonzero. This error is irremovable by any systematic methods such as increasing the resolution, setting the outer boundary at more distant location, or improving the convergence of the numerical relaxation. We discuss the possible origins for the nonsystematic error, and conclude that our result is naturally interpreted as the evidence for the nonexistence of solutions to this setup, although an "approximate" solution exists for sufficiently small brane tension. We discuss the possibility that the black holes produced on a brane may be unstable and lead to two interesting consequences: the event horizon pinch and the brane pinch.Comment: 26 pages, 9 figures, submitted to JHE

Three-Dimensional Thermal Lattice Boltzmann Simulation of Natural Convection in a Cubic Cavity

In this paper, a three-dimensional (3D) thermal lattice Boltzmann model is proposed to simulate 3D incompressible thermal flow problem. Our model is based on the double-distribution function approach. We found that a new and simple lattice type of eight-velocity model for the internal energy density distribution function can be developed, where the viscous and compressive heating effects are negligible. Numerical results of 3D natural convection flow in a cubic cavity are presented

Facial structures for various notions of positivity and applications to the theory of entanglement

In this expository note, we explain facial structures for the convex cones consisting of positive linear maps, completely positive linear maps, decomposable positive linear maps between matrix algebras, respectively. These will be applied to study the notions of entangled edge states with positive partial transposes and optimality of entanglement witnesses.Comment: An expository note. Section 7 and Section 8 have been enlarge

Cost-effectiveness Analysis of Apixaban against Warfarin for Stroke Prevention in Patients with Nonvalvular Atrial Fibrillation in Japan

Abstract Purpose The aim of this study was to evaluate the cost-effectiveness of apixaban compared with to warfarin, current standard of care, for stroke prevention in patients with nonvalvular atrial fibrillation (NVAF) in Japan. Methods A previously published lifetime Markov model was adapted to evaluate the cost-effectiveness of apixaban compared with warfarin in patients with NVAF in Japan. In the same model, the costs associated with each clinical event and background mortality were replaced with Japanese data. Whenever available, some of the utility parameters were derived from Japanese published literature. Lifetime horizon was selected to evaluate the value of the treatment benefit (stroke prevention) against potential risks (such as major bleedings) among patients with NVAF. Direct medical cost, long-term care cost, and quality-adjusted life years (QALYs) were calculated from the payers' perspective. Findings Compared with warfarin, treatment with apixaban was estimated to increase life expectancy by 0.231 year or 0.240 QALYs while treatment cost increased by ¥511,692 (US $5117 at an exchange rate of US$1 = ¥100). The incremental cost-effectiveness ratio was ¥2,135,743 per QALY (US $21,357 per QALY). On the basis of the results of the probabilistic sensitivity analysis, when the willingness-to-pay threshold was set at approximately ≥¥2,250,000 (US$22,500) per QALY, the probability of apixaban being cost-effective was ≥50%. Assuming a willingness-to-pay threshold of ¥5,000,000 (US $50,000) and ¥6,700,000 (US$67,000) in Japan, the probability of apixaban being cost-effective was 85% and 91%, respectively. Conclusion Although most participants in the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial used for the efficacy data of apixaban in the model were non-Japanese patients, the impact of the limitations on our results was considered small, and our results were deemed robust because of the additional effect in Japanese patients compared with that in the global population according to the subanalysis of Japanese patients in the trial. Therefore, based on an adaptation of a published Markov model, apixaban is a cost-effective alternative to warfarin in Japan for stroke prevention among patients with NVAF

Energy-Momentum Localization for a Space-Time Geometry Exterior to a Black Hole in the Brane World

In general relativity one of the most fundamental issues consists in defining a generally acceptable definition for the energy-momentum density. As a consequence, many coordinate-dependent definitions have been presented, whereby some of them utilize appropriate energy-momentum complexes. We investigate the energy-momentum distribution for a metric exterior to a spherically symmetric black hole in the brane world by applying the Landau-Lifshitz and Weinberg prescriptions. In both the aforesaid prescriptions, the energy thus obtained depends on the radial coordinate, the mass of the black hole and a parameter $\lambda_{0}$, while all the momenta are found to be zero. It is shown that for a special value of the parameter $\lambda_{0}$, the Schwarzschild space-time geometry is recovered. Some particular and limiting cases are also discussed.Comment: 10 pages, sections 1 and 3 slightly modified, references modified and adde

Le cadre géologique d'un site hydrothermal actif : la campagne STARMER 1 du submersible Nautile dans le Bassin Nord-Fidjien

International audienc

In situ geological and geochemical study of an active hydrothermal site on the North Fiji basin ridge

International audienc

Galileon Hairs of Dyson Spheres, Vainshtein's Coiffure and Hirsute Bubbles

We study the fields of spherically symmetric thin shell sources, a.k.a. Dyson spheres, in a {\it fully nonlinear covariant} theory of gravity with the simplest galileon field. We integrate exactly all the field equations once, reducing them to first order nonlinear equations. For the simplest galileon, static solutions come on {\it six} distinct branches. On one, a Dyson sphere surrounds itself with a galileon hair, which far away looks like a hair of any Brans-Dicke field. The hair changes below the Vainshtein scale, where the extra galileon terms dominate the minimal gradients of the field. Their hair looks more like a fuzz, because the galileon terms are suppressed by the derivative of the volume determinant. It shuts off the `hair bunching' over the `angular' 2-sphere. Hence the fuzz remains dilute even close to the source. This is really why the Vainshtein's suppression of the modifications of gravity works close to the source. On the other five branches, the static solutions are all {\it singular} far from the source, and shuttered off from asymptotic infinity. One of them, however, is really the self-accelerating branch, and the singularity is removed by turning on time dependence. We give examples of regulated solutions, where the Dyson sphere explodes outward, and its self-accelerating side is nonsingular. These constructions may open channels for nonperturbative transitions between branches, which need to be addressed further to determine phenomenological viability of multi-branch gravities.Comment: 29+1 pages, LaTeX, 2 .pdf figure