The AdS/CFT Correspondence Conjecture and Topological Censorship

In gr-qc/9902061 it was shown that (n+1)-dimensional asymptotically anti-de-Sitter spacetimes obeying natural causality conditions exhibit topological censorship. We use this fact in this paper to derive in arbitrary dimension relations between the topology of the timelike boundary-at-infinity, \scri, and that of the spacetime interior to this boundary. We prove as a simple corollary of topological censorship that any asymptotically anti-de Sitter spacetime with a disconnected boundary-at-infinity necessarily contains black hole horizons which screen the boundary components from each other. This corollary may be viewed as a Lorentzian analog of the Witten and Yau result hep-th/9910245, but is independent of the scalar curvature of \scri. Furthermore, the topology of V', the Cauchy surface (as defined for asymptotically anti-de Sitter spacetime with boundary-at-infinity) for regions exterior to event horizons, is constrained by that of \scri. In this paper, we prove a generalization of the homology results in gr-qc/9902061 in arbitrary dimension, that H_{n-1}(V;Z)=Z^k where V is the closure of V' and k is the number of boundaries $\Sigma_i$ interior to $\Sigma_0$. As a consequence, V does not contain any wormholes or other compact, non-simply connected topological structures. Finally, for the case of n=2, we show that these constraints and the onto homomorphism of the fundamental groups from which they follow are sufficient to limit the topology of interior of V to either B^2 or $I\times S^1$.Comment: Revtex, 20 page

On the Geometry and Mass of Static, Asymptotically AdS Spacetimes, and the Uniqueness of the AdS Soliton

We prove two theorems, announced in hep-th/0108170, for static spacetimes that solve Einstein's equation with negative cosmological constant. The first is a general structure theorem for spacetimes obeying a certain convexity condition near infinity, analogous to the structure theorems of Cheeger and Gromoll for manifolds of non-negative Ricci curvature. For spacetimes with Ricci-flat conformal boundary, the convexity condition is associated with negative mass. The second theorem is a uniqueness theorem for the negative mass AdS soliton spacetime. This result lends support to the new positive mass conjecture due to Horowitz and Myers which states that the unique lowest mass solution which asymptotes to the AdS soliton is the soliton itself. This conjecture was motivated by a nonsupersymmetric version of the AdS/CFT correspondence. Our results add to the growing body of rigorous mathematical results inspired by the AdS/CFT correspondence conjecture. Our techniques exploit a special geometric feature which the universal cover of the soliton spacetime shares with familiar ``ground state'' spacetimes such as Minkowski spacetime, namely, the presence of a null line, or complete achronal null geodesic, and the totally geodesic null hypersurface that it determines. En route, we provide an analysis of the boundary data at conformal infinity for the Lorentzian signature static Einstein equations, in the spirit of the Fefferman-Graham analysis for the Riemannian signature case. This leads us to generalize to arbitrary dimension a mass definition for static asymptotically AdS spacetimes given by Chru\'sciel and Simon. We prove equivalence of this mass definition with those of Ashtekar-Magnon and Hawking-Horowitz.Comment: Accepted version, Commun Math Phys; Added Remark IV.3 and supporting material dealing with non-uniqueness arising from choice of special cycle on the boundary at infinity; 2 new citations added; LaTeX 27 page

Solitons in Five Dimensional Minimal Supergravity: Local Charge, Exotic Ergoregions, and Violations of the BPS Bound

We describe a number of striking features of a class of smooth solitons in gauged and ungauged minimal supergravity in five dimensions. The solitons are globally asymptotically flat or asymptotically AdS without any Kaluza-Klein directions but contain a minimal sphere formed when a cycle pinches off in the interior of the spacetime. The solutions carry a local magnetic charge and many have rather unusual ergosurfaces. Perhaps most strikingly, many of the solitons have more electric charge or, in the asymptotically AdS case, more electric charge and angular momentum than is allowed by the usual BPS bound. We comment on, but do not resolve, the new puzzle this raises for AdS/CFT.Comment: 60 pages, 12 figures, 3 table

Doctors’ recognition and management of melanoma patients’ risk: an Australian population-based study

Background Guidelines recommend that health professionals identify and manage individuals at high risk of developing melanoma, but there is limited population-based evidence demonstrating real-world practices. Objective A population-based, observational study was conducted in the state of New South Wales, Australia to determine doctors’ knowledge of melanoma patients’ risk and to identify factors associated with better identification and clinical management. Methods Data were analysed for 1889 patients with invasive, localised melanoma in the Melanoma Patterns of Care study. This study collected data on all melanoma diagnoses notified to the state’s cancer registry during a 12-month period from 2006 to 2007, as well as questionnaire data from the doctors involved in their care. Results Three-quarters (74%) of patients had doctors who were aware of their risk factor status with respect to personal and family history of melanoma and the presence of many moles. Doctors working in general practice, skin cancer clinics and dermatology settings had better knowledge of patients’ risk factors than plastic surgeons. Doctors were 15% more likely to know the family history of younger melanoma patients (<40 years) than of those ≥80 years (95% confidence interval 4–26%). Early detection-related follow-up advice was more likely to be given to younger patients, by doctors aware of their patients’ risk status, by doctors practising in plastic surgery, dermatology and skin cancer clinic settings, and by female doctors. Conclusion Both patient-related and doctor-related factors were associated with doctors’ recognition and management of melanoma patients’ risk and could be the focus of strategies for improving care

Chemotaxis cluster 1 proteins form cytoplasmatic arrays in Vibrio cholera and are stabilized by a double signaling domain receptor DosM

FWN – Publicaties zonder aanstelling Universiteit Leide

Black Holes and Instabilities of Negative Tension Branes

We consider the collision in 2+1 dimensions of a black hole and a negative tension brane on an orbifold. Because there is no gravitational radiation in 2+1 dimensions, the horizon area shrinks when part of the brane falls through. This provides a potential violation of the generalized second law of thermodynamics. However, tracing the details of the dynamical evolution one finds that it does not proceed from equilibrium configuration to equilibrium configuration. Instead, a catastrophic space-time singularity develops similar to the `big crunch' of $\Omega >1$ FRW space-times. In the context of classical general relativity, our result demonstrates a new instability of constructions with negative tension branes.Comment: 18 pages, 3 figures, uses RevTeX. Minor typos fixed. References and one footnote adde

Tritium Beta Decay, Neutrino Mass Matrices and Interactions Beyond the Standard Model

The interference of charge-changing interactions, weaker than the V-A Standard Model (SM) interaction and having a different Lorentz structure, with that SM interaction, can, in principle, produce effects near the end point of the Tritium beta decay spectrum which are of a different character from those produced by the purely kinematic effect of neutrino mass expected in the simplest extension of the SM. We show that the existence of more than one mass eigenstate can lead to interference effects at the end point that are stronger than those occurring over the entire spectrum. We discuss these effects both for the special case of Dirac neutrinos and the more general case of Majorana neutrinos and show that, for the present precision of the experiments, one formula should suffice to express the interference effects in all cases. Implications for "sterile" neutrinos are noted.Comment: 32 pages, LaTeX, 6 figures, PostScript; full discussion and changes in notation from Phys. Lett. B440 (1998) 89, nucl-th/9807057; submitted to Phys. Rev.