A Secure and Fair Resource Sharing Model for Community Clouds

Cloud computing has gained a lot of importance and has been one of the most discussed segment of today\u27s IT industry. As enterprises explore the idea of using clouds, concerns have emerged related to cloud security and standardization. This thesis explores whether the Community Cloud Deployment Model can provide solutions to some of the concerns associated with cloud computing. A secure framework based on trust negotiations for resource sharing within the community is developed as a means to provide standardization and security while building trust during resource sharing within the community. Additionally, a model for fair sharing of resources is developed which makes the resource availability and usage transparent to the community so that members can make informed decisions about their own resource requirements based on the resource usage and availability within the community. Furthermore, the fair-share model discusses methods that can be employed to address situations when the demand for a resource is higher than the resource availability in the resource pool. Various methods that include reduction in the requested amount of resource, early release of the resources and taxing members have been studied, Based on comparisons of these methods along with the advantages and disadvantages of each model outlined, a hybrid method that only taxes members for unused resources is developed. All these methods have been studied through simulations

Quantum entanglement and Hawking temperature

The thermodynamic entropy of an isolated system is given by its von Neumann entropy. Over the last few years, there is an intense activity to understand thermodynamic entropy from the principles of quantum mechanics. More specifically, is there a relation between the (von Neumann) entropy of entanglement between a system and some (separate) environment is related to the thermodynamic entropy? It is difficult to obtain the relation for many body systems, hence, most of the work in the literature has focused on small number systems. In this work, we consider black-holes --- that are simple yet macroscopic systems --- and show that a direct connection could not be made between the entropy of entanglement and the Hawking temperature. In this work, within the adiabatic approximation, we explicitly show that the Hawking temperature is indeed given by the rate of change of the entropy of entanglement across a black hole's horizon with regard to the system energy. This is yet another numerical evidence to understand the key features of black hole thermodynamics from the viewpoint of quantum information theory.Comment: 10 pages, 5 figures (To appear in Eur. Phys. J. C

Cluster decay half lives of trans-lead nuclei within the Coulomb and proximity potential model

Within the Coulomb and proximity potential model (CPPM) the cluster decay process in {199-226}^Fr, {206-232}^Ac, {209-237}^Th, {212-238}^Pa, {217-241}^U, {225-242}^Np, {225-244}^Pu, {231-246}^Am, {202-230}^Ra and {233-249}^Cm isotopes leading to the doubly magic 208^Pb and neighbouring nuclei are studied. The computed half lives are compared with available experimental data and are in good agreement with each other. The half lives are also computed using the Universal formula for cluster decay (UNIV) of Poenaru et al, Universal decay law (UDL) and the scaling law of Horoi et al, and their comparisons with CPPM values are found to be in agreement. The calculations for the emission of 22^O, 20^O, 20^O from the parents {209-237}^Th, {202-230}^Ra and {217-240}^U respectively were the experimental values are not available are also done. It is found that most of the decay modes are favourable for measurement, and this observation will serve as a guide to the future experiments. The odd-even staggering (OES) are found to be more prominent in the emission of odd mass clusters. The Geiger - Nuttall plots of log_10(T_1/2) vs. Q^{-1/2} for various clusters ranging from 14^C to 34^Si from different isotopes of heavy parent nuclei with atomic numbers within the range 87 \leq Z \leq 96 have been studied and are found to be linear. Our study reveals the role of doubly magic 208^Pb daughter nuclei in cluster decay process and also reveal the fact that the role of neutron shell closure is crucial than proton shell closure.Comment: 39 pages, 8 figure

On the polar decomposition of right linear operators in quaternionic Hilbert spaces

In this article we prove the existence of the polar decomposition for densely defined closed right linear operators in quaternionic Hilbert spaces: If $T$ is a densely defined closed right linear operator in a quaternionic Hilbert space $H$, then there exists a partial isometry $U_{0}$ such that $T = U_{0}|T|$. In fact $U_{0}$ is unique if $N(U_{0}) = N(T)$. In particular, if $H$ is separable and $U$ is a partial isometry with $T = U|T|$, then we prove that $U = U_{0}$ if and only if either $N(T) = \{0\}$ or $R(T)^{\bot} = \{0\}$.Comment: 17 page

The red rain phenomenon of Kerala and its possible extraterrestrial origin

A red rain phenomenon occurred in Kerala, India starting from 25th July 2001, in which the rainwater appeared coloured in various localized places that are spread over a few hundred kilometers in Kerala. Maximum cases were reported during the first 10 days and isolated cases were found to occur for about 2 months. The striking red colouration of the rainwater was found to be due to the suspension of microscopic red particles having the appearance of biological cells. These particles have no similarity with usual desert dust. An estimated minimum quantity of 50,000 kg of red particles has fallen from the sky through red rain. An analysis of this strange phenomenon further shows that the conventional atmospheric transport processes like dust storms etc. cannot explain this phenomenon. The electron microscopic study of the red particles shows fine cell structure indicating their biological cell like nature. EDAX analysis shows that the major elements present in these cell like particles are carbon and oxygen. Strangely, a test for DNA using Ethidium Bromide dye fluorescence technique indicates absence of DNA in these cells. In the context of a suspected link between a meteor airburst event and the red rain, the possibility for the extraterrestrial origin of these particles from cometary fragments is discussed.Comment: 18 pages, 15 figures, accepted for publication in Astrophysics and Space Scienc