Charged and rotating Black AdS Branes in n+p+2n+p+2 dimensions

We generalize the vacuum static black brane solutions of Einstein's equations with negative cosmological constant recently discussed in literature, by introducing rotations and an electromagnetic field. We investigate numerically the thermodynamical properties of the charged and of the rotating $AdS$ black brane and we provide evidences for the existence of the charged and rotating case. In particular, we study the influence of the rotation and charge on the tension and mass. We find that the rotation essentially influences the tensions while the charge essentially influences the mass.Comment: 18 pages, 10 figure

The Initial Value Formulation of Dynamical Chern-Simons Gravity

We derive an initial value formulation for dynamical Chern-Simons gravity, a modification of general relativity involving parity-violating higher derivative terms. We investigate the structure of the resulting system of partial differential equations thinking about linearization around arbitrary backgrounds. This type of consideration is necessary if we are to establish well-posedness of the Cauchy problem. Treating the field equations as an effective field theory we find that weak necessary conditions for hyperbolicity are satisfied. For the full field equations we find that there are states from which subsequent evolution is not determined. Generically the evolution system closes, but the full field equations are in no sense hyperbolic. In a cursory mode analysis we find that the equations of motion contain terms that may cause ill-posedness of the initial value problem.Comment: 16 pages; matches published versio

Étude de la corrosion dans l'agar-agar

Aquest article explica el desenvolupament d'un treball de laboratori per estudiar la corrosió utilitzant un medi d'agar-agar i la preparació d'una pila molt senzilla que utilitza un tub d'assaig, elèctrodes i un medi d'agar-agar, també. Es presenta el procediment de laboratori de les dues experiències i es donen alguns consells i orientacions per tal de desenvolupar amb èxit les sessions pràctiques al laboratori i el treball amb els alumnes. Es donen també alguns exemples d'aplicació a la vida quotidiana.This article explains the development of a working laboratory used to study corrosion in an agar medium and a preparation of a simple battery that uses a test tube, electrodes and also a medium of agar. It presents the techniques of laboratory experiments and gives some tips and guidelines for developing successful science lab and work with students. There are also some examples of it’s application in everyday life

Inflating Brane inside hyper-spherically symmetric defects

Static and inflating brane world models are considered in $4+n$-dimensions with a non zero bulk cosmological constant and with a hyper-spherically symmetric topological defect residing in the $n$ extra dimensions. Several vacuum solutions can be constructed explicitely when the bulk and inflating constants are non zero. We study how these solutions are deformed by the presence of a global monopole for generic values of $n$ and a local monopole for $n=3$. New types of solutions, regular and periodic in the radial variable relative to the extra dimensions, are constructed.Comment: 23 pages, 9 figures, results extended, references adde

Black strings and solitons in five dimensional space-time with positive cosmological constant

We consider the classical equations of the Einstein-Yang-Mills model in five space-time dimensions and in the presence of a cosmological constant. We assume that the fields do not depend on the extra dimension and that they are spherically symmetric with respect to the three standard space dimensions. The equations are then transformed into a set of ordinary differential equations that we solve numerically. We construct new types of regular (resp. black holes) solutions which, close to the origin (resp. the event horizon) resemble the 4-dimensional gravitating monopole (resp. non abelian black hole) but exhibit an unexpected asymptotic behaviour.Comment: 13 pages, 3 figure

Van Der Waals Black Holes in dd dimensions

We generalize the recent solution proposed by Rajagopal et al. to arbitrary number of dimensions and horizon topologies. We comment on the regime of validity of these solution. Among our main results, we argue that the Van Der Waals (VDW) black hole (BH) metric is to be interpreted as a near horizon metric. This is supported by inspecting the energy conditions. We analyze the limiting cases of a perfect fluid, interacting points and non interacting balls gas equation of state and map them to known black holes. Finally, we provide a case study by comparing the Reissner-Nordstr\"om and VDW BH close to the horizon and show that they are qualitatively similar for some range of the horizon radius.Comment: 14 p., 4 figure