by extending wireless networks and because of their different nature, some attacks appear in these networks which did not exist in wired networks. security is a serious challenge for actual implementation in wireless networks. due to lack of the fixed infrastructure and also because of security holes in routing protocols in mobile ad hoc networks, these networks are not protected against attack...

We show that in complete analogy with the usual bremsstrahlung process, when studied from the coaccelerated observer’s point of view, a charge moving along the integral curves of the static Killing field in the exterior of a static black hole gives rise to the emission of zero-energy photons, induced by the thermal bath of Hawking Radiation.

We present a class of static supersymmetric multi-center black hole solutions arising in four-dimensional N = 2 supergravity theories with terms quadratic in the Weyl tensor. We also comment on possible corrections to the metric on the moduli space of these black holes solutions.

In supersymmetric theories the mass of any state is bounded below by the values of some of its charges. The corresponding bounds in the case of Schwarzschild (M & 0 ) and Reissner-Nordstrom (M & ~q~) black holes are known to coincide with the requirement that naked singularities be absent. Here we investigate [U(1)j charged dilaton black holes in this context. The extreme solutions are shown to...

We study the emergence of string instabilities in D dimensional black hole spacetimes (Schwarzschild and Reissner Nordstrøm), and De Sitter space (in static coordinates to allow a better comparison with the black hole case). We solve the first order string fluctuations around the center of mass motion at spatial infinity, near the horizon and at the spacetime singularity. We find that the time ...

Recently, Hawking radiation has been treated, by Robinson and Wilczek, as a compensating flux of the energy momentum tensor required to cancel gravitational anomaly at the event horizon(EH) of a Schwarzschild-type black hole. In this paper, motivated by their work, Hawking radiation from the event horizon(EH) and the de Sitter cosmological horizon(CH) of black holes in de Sitter spaces, specifi...

These lectures review some of the recent progress in uncovering the phase structure of black hole solutions in higher-dimensional vacuum Einstein gravity. The two classes on which we focus are Kaluza-Klein black holes, i.e. static solutions with an event horizon in asymptotically flat spaces with compact directions, and stationary solutions with an event horizon in asymptotically flat space. Hi...

We discuss quantum inequalities for minimally coupled scalar fields in static spacetimes. These are inequalities which place limits on the magnitude and duration of negative energy densities. We derive a general expression for the quantum inequality for a static observer in terms of a Euclidean two-point function. In a short sampling time limit, the quantum inequality can be written as the flat...