Dimensionally continued Oppenheimer-Snyder gravitational collapse II: solutions in odd dimensions

The Lovelock gravity extends the theory of general relativity to higher dimensions in such a way that the field equations remain of second order. The theory has many constant coefficients with no a priori meaning. Nevertheless it is possible to reduce them to two, the cosmological constant and Newton's constant. In this process one separates theories in even dimensions from theories in odd dimensions. In a previous work gravitational collapse in even dimensions was analysed. In this work attention is given to odd dimensions. It is found that black holes also emerge as the final state of gravitational collapse of a regular dust fluid.Comment: 16 pages, 3figures, latex Journal: to appear in Journal of Mathematical Physic

Gravitational magnetic monopoles and Majumdar-Papapetrou stars

A large amount of work has been dedicated to studying general relativity coupled to non-Abelian Yang-Mills type theories. It has been shown that the magnetic monopole, a solution of the Yang-Mills-Higgs equations can be coupled to gravitation. For a low Higgs mass there are regular solutions, and for a sufficiently massive monopole the system develops an extremal magnetic Reissner-Nordstrom quasi-horizon. These solutions, called quasi-black holes, although non-singular, are arbitrarily close to having a horizon. However, at the critical value the quasi-black hole turns into a degenerate spacetime. On the other hand, for a high Higgs mass, a sufficiently massive monopole develops also a quasi-black hole, but it turns into an extremal true horizon, with matter fields outside. One can also put a small Schwarzschild black hole inside the magnetic monopole, an example of a non-Abelian black hole. Surprisingly, Majumdar-Papapetrou systems, Abelian systems constructed from extremal dust, also show a resembling behavior. Previously, we have reported that one can find Majumdar-Papapetrou solutions which can be arbitrarily close of being a black hole, displaying quasi-black hole behavior. With the aim of better understanding the similarities between gravitational monopoles and Majumdar-Papapetrou systems, we study a system composed of two extremal electrically charged spherical shells (or stars, generically) in the Einstein--Maxwell--Majumdar-Papapetrou theory. We review the gravitational properties of the monopoles, and compare with the properties of the double extremal electric shell system. These quasi-black holes can help in the understanding of true black holes, and can give insight into the nature of the entropy of black holes in the form of entanglement.Comment: 38 pages,9 Figures, minor change

New concepts in global wargaming

This report addresses resurgence in wargaming and new techniques used to address complex political-military issues. Relationships between gaming and analysis are examined and benefits, opportunities, and drawbacks of gaming addressed. Requirements for Control Team in modern computer-assisted State and Path games and seminar games are discussed. Authors conclude with the value of modern simulation techniqueshttp://archive.org/details/newconceptsinglo00tritN

Exposure to violence and PTSD symptoms among Somali women

Posttraumatic stress disorder (PTSD) symptoms, exposure to traumatic stressors, and health care utilization were examined in 84 women attending a primary health care clinic in Mogadishu, Somalia. The Somalia-Posttraumatic Diagnostic Scale was used in this active warzone to measure symptoms. Nearly all women reported high levels of confrontations with violence; half described being exposed to a potentially traumatizing event. Nearly one third had significant PTSD symptoms. Compared to those who did not, women who reported exposure to a traumatic stressor reported more confrontations with violence (7.1 vs. 3.3; p < . 001), health complaints (3.8 vs. 2.9; p = .03), and nearly 3 times as much (p = .03) health service utilization. A potentially traumatizing event was found to be a simplified proxy for assessing mental health distress in women attending a primary health care facility in highly insecure, unpredictable, resource-limited settings

Quantum matter wave dynamics with moving mirrors

When a stationary reflecting wall acting as a perfect mirror for an atomic beam with well defined incident velocity is suddenly removed, the density profile develops during the time evolution an oscillatory pattern known as diffraction in time. The interference fringes are suppressed or their visibility is diminished by several effects such as averaging over a distribution of incident velocities, apodization of the aperture function, atom-atom interactions, imperfect reflection or environmental noise. However, when the mirror moves with finite velocity along the direction of propagation of the beam, the visibility of the fringes is enhanced. For mirror velocities below beam velocity, as used for slowing down the beam, the matter wave splits into three regions separated by space-time points with classical analogues. For mirror velocities above beam velocity a visibility enhancement occurs without a classical counterpart. When the velocity of the beam approaches that of the mirror the density oscillations rise by a factor 1.8 over the stationary value.Comment: 5.2 pages, 6 figure

Four-path interference and uncertainty principle in photodetachment microscopy

We study the quantal motion of electrons emitted by a pointlike monochromatic isotropic source into parallel uniform electric and magnetic fields. The two-path interference pattern in the emerging electron wave due to the electric force is modified by the magnetic lens effect which periodically focuses the beam into narrow filaments along the symmetry axis. There, four classical paths interfere. With increasing electron energy, the current distribution changes from a quantum regime governed by the uncertainty principle, to an intricate spatial pattern that yields to a semiclassical analysis.Comment: submitted to Europhysics Letter