Relativistic X-ray emission lines from the inner accretion disk around black holes are reviewed. Recent observations with the Chandra X-ray Observatory, X-ray MultiMirror Mission-Newton, and Suzaku are revealing these lines to be good probes of strong gravitational effects. A number of important observational and theoretical developments are highlighted, including evidence of black hole spin an...

We study how to explore efficiently an insecure network, namely a network that may contain a hostile node called black hole introduced by S. Dobrev, P. Flocchini, G. Prencipe, and N. Santoro (DISC 2001). A black hole is a highly harmful stationary process residing in a node of a network and destroying all mobile agents visiting the node, without leaving any trace. We consider the task of locati...

With the emergence of mobile ad-hoc networks, more users desire connectivity regardless of geographic location. MANETs are a promising technology in terms of the applications in the military, emergency situations, and general daily life activities. Various protocols have been developed to handle the routing information in such networks. However, most protocols are vulnerable to various threats....

Recently, we derived an improved universal upper bound to the entropy of a charged system S ≤ π(2Eb − q 2)/¯ h. There was, however, some uncertainty in the value of the numerical factor which multiply the q 2 term. In this paper we remove this uncertainty; we rederive this upper bound from an application of the generalized second law of thermodynamics to a gedanken experiment in which an entrop...

Recently, we derived an improved universal upper bound to the entropy of a charged system S ≤ π(2Eb − q 2)/¯ h. There was, however, some uncertainty in the value of the numerical factor which multiplies the q 2 term. In this paper we remove this uncertainty; we rederive this upper bound from an application of the generalized second law of thermodynamics to a gedanken experiment in which an entr...

MANET is a self-configuring infrastructure less network. The lacks of an infrastructure in ad hoc networks pose large challenges in the functionality of these networks. Mobile Ad Hoc Network has number of security problems that exists due to the self-configuring nature of nodes. The black hole attack is one of the well known security intimidation in wireless mobile ad hoc networks. The intruder...

Quantum gravitational effects in black hole spacetimes with a cosmological constant Λ are considered. The effective quantum spacetimes for the black holes are constructed by taking into account the renormalization group improvement of classical solutions obtained in the framework of Unimodular Gravity (a theory which is identical to General Relativity at a classical level). This allows us to av...