Rigid upper bounds for the angular momentum and centre of mass of non-singular asymptotically anti-de Sitter space-times

We prove upper bounds on angular momentum and centre of mass in terms of the Hamiltonian mass and cosmological constant for non-singular asymptotically anti-de Sitter initial data sets satisfying the dominant energy condition. We work in all space-dimensions larger than or equal to three, and allow a large class of asymptotic backgrounds, with spherical and non-spherical conformal infinities; in the latter case, a spin-structure compatibility condition is imposed. We give a large class of non-trivial examples saturating the inequality. We analyse exhaustively the borderline case in space-time dimension four: for spherical cross-sections of Scri, equality together with completeness occurs only in anti-de Sitter space-time. On the other hand, in the toroidal case, regular non-trivial initial data sets saturating the bound exist.Comment: improvements in the presentation; some statements correcte

Some Curvature Problems in Semi-Riemannian Geometry

In this survey article we review several results on the curvature of semi-Riemannian metrics which are motivated by the positive mass theorem. The main themes are estimates of the Riemann tensor of an asymptotically flat manifold and the construction of Lorentzian metrics which satisfy the dominant energy condition.Comment: 25 pages, LaTeX, 4 figure

Hémorragie digestive aiguë [Acute gastrointestinal bleeding]

Gastrointestinal bleeding is among the major clinical challenges for the gastroenterologists and the initial approach is very complex. For a big part of bleeding lesions, it is important to perform an endoscopic hemostatis after the introduction of an intravenous treatment (that has to be started as soon as there is a clinical suspicion of an upper gastrointestinal bleeding). The significant progresses made during the last years have allowed firstly to see the entire small bowel mucosa (video capsule) and secondly new treatments have successfully replaced surgical interventions

NMR studies of pore formation and water diffusion in self-hardening cut-off wall materials

Cut-off walls for the containment of polluted sites are vertical in-ground barriers of low hydraulic cond. To construct these barriers, self-hardening watery suspensions of a special cement-based hydraulic binder and a cement-stable bentonite are used. The formation of the pore structure during hardening of suspensions with different solid contents and the water self-diffusion in the resulting cut-off wall materials were studied by non-destructive 1H NMR techniques. It was found that an increased amt. of hydrating solids in the suspension leads to a decrease in NMR relaxation times and self-diffusion coeffs. of the pore water, indicating a redn. of the pore sizes and an enhancement of the diffusion resistance. The self-diffusion coeffs. of the water in the hardened cut-off wall materials were detd. to be about four orders of magnitude smaller than in bulk liq. water and two orders of magnitude smaller than in pure bentonite-water suspensions confirming the excellent diffusive resistance of the cut-off wall materials

Corrosion resistance evaluation of diamond-like carbon coatings

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