Dynamics of a Charged Particle Around a Slowly Rotating Kerr Black Hole Immersed in Magnetic Field

The dynamics of a charged particle moving around a slowly rotating Kerr black hole in the presence of an external magnetic field is investigated. We are interested to explore the conditions under which the charged particle can escape from the gravitational field of the black hole after colliding with another particle. The escape velocity of the charged particle in the innermost stable circular orbit is calculated. The effective potential and escape velocity of the charged particle with angular momentum in the presence of magnetic field is analyzed. This work serves as an extension of a preceding paper dealing with the Schwarzschild black hole [Zahrani {\it et al}, Phys. Rev. D 87, 084043 (2013)].Comment: 20 pages, 12 figure

Dynamics of Particles Around a Schwarzschild-like Black Hole in the Presence of Quintessence and Magnetic Field

We investigate the dynamics of a neutral and a charged particle around a static and spherically symmetric black hole in the presence of quintessence matter and external magnetic field. We explore the conditions under which the particle moving around the black hole could escape to infinity after colliding with another particle. The innermost stable circular orbit (ISCO) for the particles are studied in detail. Mainly the dependence of ISCO on dark energy and on the presence of external magnetic field in the vicinity of black hole is discussed. By using the Lyapunov exponent, we compare the stabilities of the orbits of the particles in the presence and absence of dark energy and magnetic field. The expressions for the center of mass energies of the colliding particles near the horizon of the black hole are derived. The effective force on the particles due to dark energy and magnetic field in the vicinity of black hole is also discussed.Comment: 25 pages, 17 figures, accepted for publication in the European Physical Journal

Performance Analysis of Modern Communication System in Realistic Environment

Multiple Input Multiple Output (MIMO) technique is one of the effective techniques to combat against fading in wireless communication system. In this thesis, based upon that, performance is evaluated for MIMO system while considering some prac­ tical scenario which was ignored for simplicity in previous works. Apart from that it is well known now a days that co-operative communication has created a new class of communication technique in wireless communication arena. It is also investigated in this thesis work how the system performs while implementing co-operative commu­nication system in an industrial application where the environment is much different from the traditional environment due to the presence of Impulse Noise. Later co­ operative communication system and the diversity technique are blended together and the performance of such system is analyzed theoretically as well as in simulation. Results acquired in this thesis will be used to bring forth publication

Strong Gravitational Lensing by Kiselev Black Hole

We investigate the gravitational lensing scenario due to Schwarzschild-like black hole surrounded by quintessence (Kiselev black hole). We work for the special case of Kiselev black hole where we take the state parameter $w_{q}=-\frac{2}{3}$. For the detailed derivation and analysis of the bending angle involved in the deflection of light, we discuss three special cases of Kiselev black hole: non-extreme, extreme and naked singularity. We also calculate the approximate bending angle and compare it with exact bending angle. We found the relation of bending angles in the decreasing order as: naked singularity, extreme Kiselev black hole, non-extreme Kiselev black hole and Schwarzschild black hole. In the weak field approximation, we compute the position and total magnification of relativistic images as well

Generalized Second Law of Thermodynamics for FRW Cosmology with Power-Law Entropy Correction

In this work, we have considered the power law correction of entropy on the horizon. If the flat FRW Universe is filled with the n components fluid with interactions, the GSL of thermodynamics for apparent and event horizons have been investigated for equilibrium and non-equilibrium cases. If we consider a small perturbation around the de Sitter space-time, the general conditions of the validity of GSL have been found. Also if a phantom dominated Universe has a polelike type scale factor, the validity of GSL has also been analyzed. Further we have obtained constraints on the power-law parameter {\alpha} in the phantom and quintessence dominated regimes. Finally we obtain conditions under which GSL breaks down in a cosmological background.Comment: 10 page

IT Ethics: Undergraduates’ PerceptionBased on their Awareness

Vide acceptance and use of computer and information technology in universities demanded the researchers and teachers to train their students to use these resources ethically. In the universities of Pakistan, computer and IT related courses have recently been included as compulsory subjects. Therefore, this research aimed to explore the perceptions about ethical use of information technology (IT) by the undergraduate students from four different public and private sector universities. A questionnaire was designed in which different computer and internet related activities were given and students were required to respond in terms of Right, Wrong and Neither Right Nor Wrong. Total 542 students participated in the study and the results were interpreted on the bases of their demographic information. It was concluded that majority of the students were not previously trained and have no knowledge about computer or IT ethics. It was found that female students, students from public sector universities, from different departments of computing and IT and from the disciplines of pure sciences were perceptually more positive regarding the ethical use of IT resources. Minimal differences were found across the responses of students who have IT training certificates and prior knowledge of IT ethics. This suggests that computer ethics awareness training is needed for university students. Keywords: Computer ethics, IT ethics, Undergraduate Students, Education, Sciences vs Social Sciences, Male vs Female, Public-sector vs Private-sector universities.

Particle Dynamics Around Weakly Magnetized Reissner-Nordstr\"{o}m Black Hole

Considering the geometry of Reissner-Nordstr\"{o}m (RN) black hole immersed in magnetic field we have studied the dynamics of neutral and charged particles. A collision of particles in the inner stable circular orbit is considered and the conditions for the escape of colliding particles from the vicinity of black hole are given. The trajectories of the escaping particle are discussed. Also the velocity required for this escape is calculated. It is observed that there are more than one stable regions if magnetic field is present in the accretion disk of black hole so the stability of ISCO increases in the presence of magnetic field. Effect of magnetic field on the angular motion of neutral and charged particles is observed graphically.Comment: 16 pages, 16 figures, version accepted for publication in 'Advances in High Energy Physics