AR_final file_2018-19

Link deletion in directed complex networks We present a systematic and detailed study of the robustness of directed networks under random and targeted removal of links. We work with a set of network models of random and scale free type, gen- erated with specific features of clustering and assor- tativity. Various strategies like random deletion of links, or deletions based on betweenness centrality and degrees of source and target nodes, are used to breakdown the networks. The robustness of the networks to the sustained loss of links is studied in terms of the sizes of the connected components and the inverse path lengths. The effects of cluster- ing and 2-node degree correlations, on the robust- ness to attack, are also explored. We provide spe- cific illustrations of our study on three real-world networks constructed from protein-protein interac- tions and from transport data. This work has been done in collaboration with G. Kashyap. Bijan Kumar Bagchi Quantum, non-commutative and MOND correc- tions to the entropic law of gravitation Quantum and non-commutative corrections to the Newtonian law of inertia are considered in the gen- eral setting of Verlinde’s entropic force postulate. We demonstrate that the form for the modified Newtonian dynamics (MOND) emerges in a classi- cal setting by seeking appropriate corrections in the entropy. We estimate the correction term by using concrete coherent states in the standard and gener- alized versions of Heisenberg’s uncertainty princi- ple. Using Jackiw’s direct and analytic method, we compute the explicit wavefunctions for these states, producing minimal length as well as min- imal products. Subsequently, we derive a further selection criterium restricting the free parameters in the model in providing a canonical formulation of the quantum corrected Newtonian law by set- ting up the Lagrangian and Hamiltonian for the system. This work has been done in collaboration with Andreas Fring. Tanwi Bandyopadhyay Bouncing universe in the contexts of generalized cosmic Chaplygin Gas and variable modified Chap- lygin gas In this work, we have considered the Friedmann- Robertson-Walker (FRW) model of the universe, where bounce occurs and the universe is filled with Generalized Cosmic Chaplygin Gas (GCCG) or Variable Modified Chaplygin Gas (VMCG). We have studied the stability analysis through dynam- ical system for both models and found the criti- cal points in flat, open and closed universe. In presence of scalar field, the dynamical behaviour of scale factor and Hubble parameter are described in both models. Finally, we have analyzed the en- ergy conditions for both the models in bouncing universe.This work has been done in collaboration with Ujjal Debnath. Thermodynamic prescription of cosmological con- stant in Randall Sundrum-II brane In this work, we apply quantum corrected entropy function derived from the Generalized Uncertainty Principle (GUP) to the Holographic Equipartition Law to study the cosmological scenario in Randall- Sundrum (RS) II brane. An extra driving term has come up in the effective Friedmann equation for a homogeneous, isotropic and spatially flat uni- verse. Further, thermodynamic prescription of the universe constraints this term eventually with or- der equivalent to that of the cosmological constant. Prasad Basu Gravitational wave emission from binary mergers: Ideal versus real picture We give here a brief review of the works study- ing the signatures of accretion disks on the grav- itational wave signals generated by extreme mass ratio binary systems of compact objects. An ex- ample of such a system is a stellar mass compact star (typically a neutron star or a black hole) or- biting a central super-massive black hole embedded in a massive accretion disk. We particularly focus on the effects produced by hydrodynamic drag of the disk on the orbiting companion and find that the drag effects produced by the disk matter are indeed capable of modifying the companion’s mo- tion and hence, the gravitational wave signal emit- ted from the system. The nature and significance of the effect depends crucially on the flow param- eters of the disk, e.g., velocity, density profiles of the flow. Therefore, on one hand, one needs to incorporate these effects while theoretically mod- elling the gravitational wave signal emitted from such systems. On the other hand, by studying the emitted gravitational wave signals profile, one ( 175 )