Flavored Co-annihilations

Neutralino dark matter in supersymmetric models is revisited in the presence of flavor violation in the soft supersymmetry breaking sector. We focus on flavor violation in the sleptonic sector and study the implications for the co-annihilation regions. Flavor violation is introduced by a single $\tilde{\mu}_R-\tilde{\tau}_R$ insertion in the slepton mass matrix. Limits on this insertion from BR($\tau \to \mu + \gamma$) are weak in some regions of the parameter space where cancellations happen within the amplitudes. We look for overlaps in parameter space where both the co-annihilation condition as well as the cancellations within the amplitudes occur. In mSUGRA, such overlap regions are not existent, whereas they are present in models with non-universal Higgs boundary conditions (NUHM). The effect of flavor violation is two fold: (a) it shifts the co-annihilation regions towards lighter neutralino masses (b) the co-annihilation cross sections would be modified with the inclusion of flavor violating diagrams which can contribute significantly. Even if flavor violation is within the presently allowed limits, this is sufficient to modify the thermally averaged cross-sections by about (10-15)% in mSUGRA and (20-30)% in NUHM, depending on the parameter space. In the overlap regions, the flavor violating cross sections become comparable and in some cases even dominant to the flavor conserving ones. A comparative study of the channels is presented for mSUGRA and NUHM cases.Comment: 38 pages, 28 figures. Significantly expanded and improved version with a new section on channels and new appendices on mSUGRA and cross-sections, version accepted for publication in JHE

Magnetization dynamics in disordered Fex_xCo1−x_{1-x} alloys : A first-principles augmented space approach and atomistic spin dynamics simulations

In this paper, we present a general method to study magnetization dynamics in chemically disordered alloys. This computationally feasible technique, which seamlessly combines three approaches : the density functional based linear muffin-tin orbitals (LMTO) for self-consistently obtaining a sparse Hamiltonian; the generalized recursion method to obtain the one and two-particle Green functions and augmented space approach to deal with disorder averaging. The same formalism applied to both spectral and response properties should make the errors compatible in different studies. %The underlying computational routines are optimized and parallelized for ease of handling. We have demonstrated a successful application to the binary chemically disordered Fe$_x$Co$_{1-x}$ alloys to explain several experimental features in magnon spectra. Our study captures significant magnon softening due to magnon-electron scattering for chemically disordered Fe$_x$Co$_{1-x}$ alloys within linear spin wave regime. As a complementary study, we have done atomistic spin dynamics simulations by solving Landau-Lifshitz-Gilbert equation with parameters obtained from ab initio multiple scattering theory to compare with the results obtained from augmented space approach.Comment: arXiv admin note: text overlap with arXiv:1102.4551, arXiv:1304.7091 by other author

CIMTDetect: A Community Infused Matrix-Tensor Coupled Factorization Based Method for Fake News Detection

Detecting whether a news article is fake or genuine is a crucial task in today's digital world where it's easy to create and spread a misleading news article. This is especially true of news stories shared on social media since they don't undergo any stringent journalistic checking associated with main stream media. Given the inherent human tendency to share information with their social connections at a mouse-click, fake news articles masquerading as real ones, tend to spread widely and virally. The presence of echo chambers (people sharing same beliefs) in social networks, only adds to this problem of wide-spread existence of fake news on social media. In this paper, we tackle the problem of fake news detection from social media by exploiting the very presence of echo chambers that exist within the social network of users to obtain an efficient and informative latent representation of the news article. By modeling the echo-chambers as closely-connected communities within the social network, we represent a news article as a 3-mode tensor of the structure - and propose a tensor factorization based method to encode the news article in a latent embedding space preserving the community structure. We also propose an extension of the above method, which jointly models the community and content information of the news article through a coupled matrix-tensor factorization framework. We empirically demonstrate the efficacy of our method for the task of Fake News Detection over two real-world datasets. Further, we validate the generalization of the resulting embeddings over two other auxiliary tasks, namely: \textbf{1)} News Cohort Analysis and \textbf{2)} Collaborative News Recommendation. Our proposed method outperforms appropriate baselines for both the tasks, establishing its generalization.Comment: Presented at ASONAM'1

Bacterial Foraging Based Channel Equalizers

A channel equalizer is one of the most important subsystems in any digital communication receiver. It is also the subsystem that consumes maximum computation time in the receiver. Traditionally maximum-likelihood sequence estimation (MLSE) was the most popular form of equalizer. Owing to non-stationary characteristics of the communication channel MLSE receivers perform poorly. Under these circumstances ‘Maximum A-posteriori Probability (MAP)’ receivers also called Bayesian receivers perform better. Natural selection tends to eliminate animals with poor “foraging strategies” and favor the propagation of genes of those animals that have successful foraging strategies since they are more likely to enjoy reproductive success. After many generations, poor foraging strategies are either eliminated or shaped into good ones (redesigned). Logically, such evolutionary principles have led scientists in the field of “foraging theory” to hypothesize that it is appropriate to model the activity of foraging as an optimization process. This thesis presents an investigation on design of bacterial foraging based channel equalizer for digital communication. Extensive simulation studies shows that the performance of the proposed receiver is close to optimal receiver for variety of channel conditions. The proposed receiver also provides near optimal performance when channel suffers from nonlinearities

A Literature Review on the Employability and the Effects of Ex-Military Personnel in Corporate Boardrooms

Military Personnel throughout the globe, especially at the Officer level are known to be selected on a very stringent basis for military service based on specific personality traits that can be groomed by the Military for its own purpose. Subsequently, they are made to go through series of well-designed training programmes that grooms them into world-class leaders. Their training is known to continue throughout their service careers. However, the skills, qualities, and habits those officers are known to gain through their experiences whether in combat or in normal regimental life are something that no other institution in the world may be able to inculcate. Thus after the service careers, their employability within the corporate world is considered to be invaluable. The paper reviews the literature available to correlate the association between military and the corporate world. Previous researchers are reviewed is to discuss various skill sets/ qualities that are desirable to succeed in the corporate world such as communication skills, offbeat thinking, optimism, adaptability etc. vis-s-vis a SWOT analysis of the personality traits of ex-military personnel as documented by researchers. Finally, with the help of previously researched work the paper highlights as to what do the firms achieve in employing military personnel or why and when do they prefer hiring ex-military personnel for their top jobs. Keywords: Ex- Military Personnel, Board room

Parallelization of Dial-a-Ride Using Tabu Search

Dial-A-Ride is a transport system heavily constrained by following fleet size, vehicle capacity, and a fixed number of requests (pickup and drop-off points) with time windows. It is often modelled as Integer Programming, various solutions are proposed using heuristics. One such heuristic is Tabu Search . Tabu Search is very CPU intensive with its process of search, therefore many modern computing techniques like using GPUs have been employed to make it efficient. As with many other greedy algorithms, the local optima is not always the same as the global optima, so it is not possible to go past the local optima using greedy techniques for this problem. It is often modelled as Integer Programming, with the search space being very big, there are proven to not be so efficient. So, many heuristics have been proposed in the past, one such heuristic is Tabu Search . The local search of this heuristic uses memory to keep track of recent moves made and tries to avoid them for specified iterations (marks as Tabu) and also continues to explore the neighbourhood search space even with the degradation optimization function value, thus helping the algorithm to go past the local optima towards global optima. This thesis focuses on limitations of parallelizing DARP-TS for multi-core CPU, discussing major factors like (i) number of good moves in the neighbourhood and how we can estimate a value for N\_SIZE (number of parallel moves to make in each iteration), (ii) difference between a CPU core and a GPU core in the context of thread scheduling, memory layout and memory limitations, (iii) proposes few data-structures to keep the memory allocations low thus reducing the time for garbage collection and (iv) proposes an incremental way of calculating the value of optimization function in the local search phase which helps in mapping the execution and evaluation of N\_SIZE moves in each iteration onto the multiple CPU cores