Isometric Embedding of BPS Branes in Flat Spaces with Two Times

We show how non-near horizon p-brane theories can be obtained from two embedding constraints in a flat higher dimensional space with 2 time directions. In particular this includes the construction of D3 branes from a flat 12-dimensional action, and M2 and M5 branes from 13 dimensions. The worldvolume actions are determined by constant forms in the higher dimension, reduced to the usual expressions by Lagrange multipliers. The formulation affords insight in the global aspects of the spacetime geometries and makes contact with recent work on two-time physics.Comment: 29 pages, 10 figures, Latex using epsf.sty and here.sty; v2: reference added and some small correction

Geometric entropy, area, and strong subadditivity

The trace over the degrees of freedom located in a subset of the space transforms the vacuum state into a density matrix with non zero entropy. This geometric entropy is believed to be deeply related to the entropy of black holes. Indeed, previous calculations in the context of quantum field theory, where the result is actually ultraviolet divergent, have shown that the geometric entropy is proportional to the area for a very special type of subsets. In this work we show that the area law follows in general from simple considerations based on quantum mechanics and relativity. An essential ingredient of our approach is the strong subadditive property of the quantum mechanical entropy.Comment: Published versio

Bounds on masses of bulk fields in string compactifications

In string compactification on a manifold X, in addition to the string scale and the normal scales of low-energy particle physics, there is a Kaluza-Klein scale 1/R associated with the size of X. We present an argument that generic string models with low-energy supersymmetry have, after moduli stabilization, bulk fields with masses which are parametrically lighter than 1/R. We discuss the implications of these light states for anomaly mediation and gaugino mediation scenarios.Comment: 15 page

Kinetic models of heterogeneous dissipation

We suggest kinetic models of dissipation for an ensemble of interacting oriented particles, for example, moving magnetized particles. This is achieved by introducing a double bracket dissipation in kinetic equations using an oriented Poisson bracket, and employing the moment method to derive continuum equations for magnetization and density evolution. We show how our continuum equations generalize the Debye-Hueckel equations for attracting round particles, and Landau-Lifshitz-Gilbert equations for spin waves in magnetized media. We also show formation of singular solutions that are clumps of aligned particles (orientons) starting from random initial conditions. Finally, we extend our theory to the dissipative motion of self-interacting curves.Comment: 28 pages, 2 figures. Submitted to J. Phys.

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access