Results for "Sham M. Kakade"

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Learning Mixtures of Gaussians in High DimensionsMar 02 2015Mar 10 2015Efficiently learning mixture of Gaussians is a fundamental problem in statistics and learning theory. Given samples coming from a random one out of k Gaussian distributions in Rn, the learning problem asks to estimate the means and the covariance matrices ... More
Recovering Structured Probability MatricesFeb 21 2016Apr 15 2016We consider the problem of accurately recovering a matrix B of size M by M , which represents a probability distribution over M2 outcomes, given access to an observed matrix of "counts" generated by taking independent samples from the distribution B. ... More
Maximum Likelihood Estimation for Learning Populations of ParametersFeb 12 2019Consider a setting with $N$ independent individuals, each with an unknown parameter, $p_i \in [0, 1]$ drawn from some unknown distribution $P^\star$. After observing the outcomes of $t$ independent Bernoulli trials, i.e., $X_i \sim \text{Binomial}(t, ... More
Canonical Correlation Analysis for Analyzing Sequences of Medical Billing CodesDec 01 2016We propose using canonical correlation analysis (CCA) to generate features from sequences of medical billing codes. Applying this novel use of CCA to a database of medical billing codes for patients with diverticulitis, we first demonstrate that the CCA ... More
A Short Note on Concentration Inequalities for Random Vectors with SubGaussian NormFeb 11 2019In this note, we derive concentration inequalities for random vectors with subGaussian norm (a generalization of both subGaussian random vectors and norm bounded random vectors), which are tight up to logarithmic factors.
Stochastic Gradient Descent Escapes Saddle Points EfficientlyFeb 13 2019This paper considers the perturbed stochastic gradient descent algorithm and shows that it finds $\epsilon$-second order stationary points ($\left\|\nabla f(x)\right\|\leq \epsilon$ and $\nabla^2 f(x) \succeq -\sqrt{\epsilon} \mathbf{I}$) in $\tilde{O}(d/\epsilon^4)$ ... More
Stochastic subgradient method converges on tame functionsApr 20 2018May 26 2018This work considers the question: what convergence guarantees does the stochastic subgradient method have in the absence of smoothness and convexity? We prove that the stochastic subgradient method, on any semialgebraic locally Lipschitz function, produces ... More
Learning mixtures of spherical Gaussians: moment methods and spectral decompositionsJun 25 2012Oct 28 2012This work provides a computationally efficient and statistically consistent moment-based estimator for mixtures of spherical Gaussians. Under the condition that component means are in general position, a simple spectral decomposition technique yields ... More
Super-Resolution Off the GridSep 26 2015Super-resolution is the problem of recovering a superposition of point sources using bandlimited measurements, which may be corrupted with noise. This signal processing problem arises in numerous imaging problems, ranging from astronomy to biology to ... More
A Method of Moments for Mixture Models and Hidden Markov ModelsMar 03 2012Sep 05 2012Mixture models are a fundamental tool in applied statistics and machine learning for treating data taken from multiple subpopulations. The current practice for estimating the parameters of such models relies on local search heuristics (e.g., the EM algorithm) ... More
An Optimal Dynamic Mechanism for Multi-Armed Bandit ProcessesJan 26 2010Oct 15 2010We consider the problem of revenue-optimal dynamic mechanism design in settings where agents' types evolve over time as a function of their (both public and private) experience with items that are auctioned repeatedly over an infinite horizon. A central ... More
A tail inequality for quadratic forms of subgaussian random vectorsOct 13 2011We prove an exponential probability tail inequality for positive semidefinite quadratic forms in a subgaussian random vector. The bound is analogous to one that holds when the vector has independent Gaussian entries.
Identifiability and Unmixing of Latent Parse TreesJun 14 2012This paper explores unsupervised learning of parsing models along two directions. First, which models are identifiable from infinite data? We use a general technique for numerically checking identifiability based on the rank of a Jacobian matrix, and ... More
A Spectral Algorithm for Learning Hidden Markov ModelsNov 26 2008Jul 06 2012Hidden Markov Models (HMMs) are one of the most fundamental and widely used statistical tools for modeling discrete time series. In general, learning HMMs from data is computationally hard (under cryptographic assumptions), and practitioners typically ... More
Dimension-free tail inequalities for sums of random matricesApr 09 2011Apr 16 2011We derive exponential tail inequalities for sums of random matrices with no dependence on the explicit matrix dimensions. These are similar to the matrix versions of the Chernoff bound and Bernstein inequality except with the explicit matrix dimensions ... More
Robust Matrix Decomposition with OutliersNov 05 2010Dec 04 2010Suppose a given observation matrix can be decomposed as the sum of a low-rank matrix and a sparse matrix (outliers), and the goal is to recover these individual components from the observed sum. Such additive decompositions have applications in a variety ... More
Provable Efficient Online Matrix Completion via Non-convex Stochastic Gradient DescentMay 26 2016Matrix completion, where we wish to recover a low rank matrix by observing a few entries from it, is a widely studied problem in both theory and practice with wide applications. Most of the provable algorithms so far on this problem have been restricted ... More
Random design analysis of ridge regressionJun 13 2011Mar 25 2014This work gives a simultaneous analysis of both the ordinary least squares estimator and the ridge regression estimator in the random design setting under mild assumptions on the covariate/response distributions. In particular, the analysis provides sharp ... More
Analysis of a randomized approximation scheme for matrix multiplicationNov 23 2012This note gives a simple analysis of a randomized approximation scheme for matrix multiplication proposed by Sarlos (2006) based on a random rotation followed by uniform column sampling. The result follows from a matrix version of Bernstein's inequality ... More
(weak) Calibration is Computationally HardFeb 20 2012We show that the existence of a computationally efficient calibration algorithm, with a low weak calibration rate, would imply the existence of an efficient algorithm for computing approximate Nash equilibria - thus implying the unlikely conclusion that ... More
A Linear Dynamical System Model for TextFeb 13 2015May 31 2015Low dimensional representations of words allow accurate NLP models to be trained on limited annotated data. While most representations ignore words' local context, a natural way to induce context-dependent representations is to perform inference in a ... More
Un-regularizing: approximate proximal point and faster stochastic algorithms for empirical risk minimizationJun 24 2015We develop a family of accelerated stochastic algorithms that minimize sums of convex functions. Our algorithms improve upon the fastest running time for empirical risk minimization (ERM), and in particular linear least-squares regression, across a wide ... More
Regularization Techniques for Learning with MatricesOct 04 2009Oct 17 2010There is growing body of learning problems for which it is natural to organize the parameters into matrix, so as to appropriately regularize the parameters under some matrix norm (in order to impose some more sophisticated prior knowledge). This work ... More
Planning in POMDPs Using Multiplicity AutomataJul 04 2012Planning and learning in Partially Observable MDPs (POMDPs) are among the most challenging tasks in both the AI and Operation Research communities. Although solutions to these problems are intractable in general, there might be special cases, such as ... More
Gaussian Process Optimization in the Bandit Setting: No Regret and Experimental DesignDec 21 2009Jun 09 2010Many applications require optimizing an unknown, noisy function that is expensive to evaluate. We formalize this task as a multi-armed bandit problem, where the payoff function is either sampled from a Gaussian process (GP) or has low RKHS norm. We resolve ... More
Learning Exponential Families in High-Dimensions: Strong Convexity and SparsityOct 31 2009May 16 2015The versatility of exponential families, along with their attendant convexity properties, make them a popular and effective statistical model. A central issue is learning these models in high-dimensions, such as when there is some sparsity pattern of ... More
Competing with the Empirical Risk Minimizer in a Single PassDec 20 2014Feb 25 2015In many estimation problems, e.g. linear and logistic regression, we wish to minimize an unknown objective given only unbiased samples of the objective function. Furthermore, we aim to achieve this using as few samples as possible. In the absence of computational ... More
Multi-Label Prediction via Compressed SensingFeb 08 2009Jun 02 2009We consider multi-label prediction problems with large output spaces under the assumption of output sparsity -- that the target (label) vectors have small support. We develop a general theory for a variant of the popular error correcting output code scheme, ... More
A Smoother Way to Train Structured Prediction ModelsFeb 08 2019We present a framework to train a structured prediction model by performing smoothing on the inference algorithm it builds upon. Smoothing overcomes the non-smoothness inherent to the maximum margin structured prediction objective, and paves the way for ... More
Towards minimax policies for online linear optimization with bandit feedbackFeb 14 2012We address the online linear optimization problem with bandit feedback. Our contribution is twofold. First, we provide an algorithm (based on exponential weights) with a regret of order $\sqrt{d n \log N}$ for any finite action set with $N$ actions, under ... More
Computing Matrix Squareroot via Non Convex Local SearchJul 21 2015We consider the problem of computing the squareroot of a positive semidefinite (PSD) matrix. Several fast algorithms (some based on eigenvalue decomposition and some based on Taylor expansion) are known to solve this problem. In this paper, we propose ... More
A Tensor Approach to Learning Mixed Membership Community ModelsFeb 12 2013Oct 24 2013Community detection is the task of detecting hidden communities from observed interactions. Guaranteed community detection has so far been mostly limited to models with non-overlapping communities such as the stochastic block model. In this paper, we ... More
Learning Topic Models and Latent Bayesian Networks Under Expansion ConstraintsSep 24 2012May 24 2013Unsupervised estimation of latent variable models is a fundamental problem central to numerous applications of machine learning and statistics. This work presents a principled approach for estimating broad classes of such models, including probabilistic ... More
Tracking yeast pheromone receptor Ste2 endocytosis using fluorogen-activating protein taggingJan 21 2019To observe internalization of the yeast pheromone receptor Ste2 by fluorescence microscopy in live cells in real time, we visualized only those molecules present at the cell surface at the time of agonist engagement (rather than the total cellular pool) ... More
An Optimal Algorithm for Linear BanditsOct 19 2011Feb 14 2012We provide the first algorithm for online bandit linear optimization whose regret after T rounds is of order sqrt{Td ln N} on any finite class X of N actions in d dimensions, and of order d*sqrt{T} (up to log factors) when X is infinite. These bounds ... More
Tensor decompositions for learning latent variable modelsOct 29 2012Nov 13 2014This work considers a computationally and statistically efficient parameter estimation method for a wide class of latent variable models---including Gaussian mixture models, hidden Markov models, and latent Dirichlet allocation---which exploits a certain ... More
Efficient Algorithms for Large-scale Generalized Eigenvector Computation and Canonical Correlation AnalysisApr 13 2016May 27 2016This paper considers the problem of canonical-correlation analysis (CCA) (Hotelling, 1936) and, more broadly, the generalized eigenvector problem for a pair of symmetric matrices. These are two fundamental problems in data analysis and scientific computing ... More
Faster Eigenvector Computation via Shift-and-Invert PreconditioningMay 26 2016We give faster algorithms and improved sample complexities for estimating the top eigenvector of a matrix $\Sigma$ -- i.e. computing a unit vector $x$ such that $x^T \Sigma x \ge (1-\epsilon)\lambda_1(\Sigma)$: Offline Eigenvector Estimation: Given an ... More
Robust Shift-and-Invert Preconditioning: Faster and More Sample Efficient Algorithms for Eigenvector ComputationOct 29 2015May 30 2016We provide faster algorithms and improved sample complexities for approximating the top eigenvector of a matrix. Offline Setting: Given an $n \times d$ matrix $A$, we show how to compute an $\epsilon$ approximate top eigenvector in time $\tilde O ( [nnz(A) ... More
Spectral Methods for Learning Multivariate Latent Tree StructureJul 07 2011Nov 08 2011This work considers the problem of learning the structure of multivariate linear tree models, which include a variety of directed tree graphical models with continuous, discrete, and mixed latent variables such as linear-Gaussian models, hidden Markov ... More
A Risk Comparison of Ordinary Least Squares vs Ridge RegressionMay 04 2011May 31 2013We compare the risk of ridge regression to a simple variant of ordinary least squares, in which one simply projects the data onto a finite dimensional subspace (as specified by a Principal Component Analysis) and then performs an ordinary (un-regularized) ... More
Parallelizing Stochastic Approximation Through Mini-Batching and Tail-AveragingOct 12 2016Oct 27 2016This work characterizes the benefits of averaging techniques widely used in conjunction with stochastic gradient descent (SGD). In particular, this work sharply analyzes: (1) mini-batching, a method of averaging many samples of the gradient to both reduce ... More
A Spectral Algorithm for Latent Dirichlet AllocationApr 30 2012Jan 17 2013The problem of topic modeling can be seen as a generalization of the clustering problem, in that it posits that observations are generated due to multiple latent factors (e.g., the words in each document are generated as a mixture of several active topics, ... More
Stochastic convex optimization with bandit feedbackJul 08 2011Oct 08 2011This paper addresses the problem of minimizing a convex, Lipschitz function $f$ over a convex, compact set $\xset$ under a stochastic bandit feedback model. In this model, the algorithm is allowed to observe noisy realizations of the function value $f(x)$ ... More
Parallelizing Stochastic Approximation Through Mini-Batching and Tail-AveragingOct 12 2016This work characterizes the benefits of averaging techniques widely used in conjunction with stochastic gradient descent (SGD). In particular, this work sharply analyzes: (1) mini-batching, a method of averaging many samples of the gradient to both reduce ... More
Streaming PCA: Matching Matrix Bernstein and Near-Optimal Finite Sample Guarantees for Oja's AlgorithmFeb 22 2016Mar 28 2016This work provides improved guarantees for streaming principle component analysis (PCA). Given $A_1, \ldots, A_n\in \mathbb{R}^{d\times d}$ sampled independently from distributions satisfying $\mathbb{E}[A_i] = \Sigma$ for $\Sigma \succeq \mathbf{0}$, ... More
Least Squares Revisited: Scalable Approaches for Multi-class PredictionOct 07 2013Oct 21 2013This work provides simple algorithms for multi-class (and multi-label) prediction in settings where both the number of examples n and the data dimension d are relatively large. These robust and parameter free algorithms are essentially iterative least-squares ... More
Domain Adaptation: Overfitting and Small Sample StatisticsMay 04 2011We study the prevalent problem when a test distribution differs from the training distribution. We consider a setting where our training set consists of a small number of sample domains, but where we have many samples in each domain. Our goal is to generalize ... More
Unveiling the universality of I-Love-Q relationsOct 30 2014Jan 13 2015The recent discovery of the universal I-Love-Q relations connecting the moment of inertia, tidal deformability, and the spin-induced quadrupole moment of compact stars is intriguing and totally unexpected. In this paper, we provide numerical evidence ... More
Learning Features of Music from ScratchNov 29 2016We introduce a new large-scale music dataset, MusicNet, to serve as a source of supervision and evaluation of machine learning methods for music research. MusicNet consists of hundreds of freely-licensed classical music recordings by 10 composers, written ... More
Variance Reduction for Policy Gradient with Action-Dependent Factorized BaselinesMar 20 2018Policy gradient methods have enjoyed great success in deep reinforcement learning but suffer from high variance of gradient estimates. The high variance problem is particularly exasperated in problems with long horizons or high-dimensional action spaces. ... More
Learning from Logged Implicit Exploration DataFeb 27 2010Jun 14 2010We provide a sound and consistent foundation for the use of \emph{nonrandom} exploration data in "contextual bandit" or "partially labeled" settings where only the value of a chosen action is learned. The primary challenge in a variety of settings is ... More
Prediction with a Short MemoryDec 08 2016We consider the problem of predicting the next observation given a sequence of past observations. We show that for any distribution over observations, if the mutual information between past observations and future observations is upper bounded by $I$, ... More
Convergence Rates of Active Learning for Maximum Likelihood EstimationJun 08 2015An active learner is given a class of models, a large set of unlabeled examples, and the ability to interactively query labels of a subset of these examples; the goal of the learner is to learn a model in the class that fits the data well. Previous theoretical ... More
When are Overcomplete Topic Models Identifiable? Uniqueness of Tensor Tucker Decompositions with Structured SparsityAug 13 2013Overcomplete latent representations have been very popular for unsupervised feature learning in recent years. In this paper, we specify which overcomplete models can be identified given observable moments of a certain order. We consider probabilistic ... More
Efficient Learning of Generalized Linear and Single Index Models with Isotonic RegressionApr 11 2011Generalized Linear Models (GLMs) and Single Index Models (SIMs) provide powerful generalizations of linear regression, where the target variable is assumed to be a (possibly unknown) 1-dimensional function of a linear predictor. In general, these problems ... More
Minimal Realization Problems for Hidden Markov ModelsNov 13 2014Dec 14 2015Consider a stationary discrete random process with alphabet size d, which is assumed to be the output process of an unknown stationary Hidden Markov Model (HMM). Given the joint probabilities of finite length strings of the process, we are interested ... More
High-Q gigahertz surface acoustic wave cavity on lithium niobateJan 25 2019Phonons at gigahertz frequencies interact with electrons, photons, and atomic systems in solids, and therefore have extensive applications in signal processing, sensing, and quantum technologies. Surface acoustic wave (SAW) cavities that confine surface ... More
Robust Distant Entanglement Generation Using Coherent Multiphoton ScatteringFeb 11 2013We describe a protocol to entangle two qubits at a distance by using resonance fluorescence. The scheme makes use of the postselection of large and distinguishable fluorescence signals corresponding to entangled and unentangled qubit states and has the ... More
Leverage Score Sampling for Faster Accelerated Regression and ERMNov 22 2017Given a matrix $\mathbf{A}\in\mathbb{R}^{n\times d}$ and a vector $b \in\mathbb{R}^{d}$, we show how to compute an $\epsilon$-approximate solution to the regression problem $ \min_{x\in\mathbb{R}^{d}}\frac{1}{2} \|\mathbf{A} x - b\|_{2}^{2} $ in time ... More
SUSY Signals from QCD Production at the Upgraded LHCFeb 13 2019Weak-scale supersymmetry remains to be one of the best-motivated theories of physics beyond the Standard Model. We evaluate the sensitivities of the High Luminosity (HL) and High Energy (HE) upgrades of the LHC to gluinos and stops, decaying through the ... More
Ultrafast switching time and third order nonlinear coefficients of microwave treated single walled carbon nanotube suspensionsJul 09 2008Microwave treated water soluble and amide functionalized single walled carbon nanotubes have been investigated using femtosecond degenerate pump-probe and nonlinear transmission experiments. The time resolved differential transmission using 75 femtosecond ... More
Learning High-Dimensional Mixtures of Graphical ModelsMar 04 2012Jun 30 2012We consider unsupervised estimation of mixtures of discrete graphical models, where the class variable corresponding to the mixture components is hidden and each mixture component over the observed variables can have a potentially different Markov graph ... More
On certain classes of harmonic functions defined by the fractional derivativesJul 16 2009In this paper we have introduced two new classes $\mathcal{H}\mathcal{M}(\beta, \lambda, k, \nu)$ and $\overline{\mathcal{H}\mathcal{M}} (\beta, \lambda, k, \nu)$ of complex valued harmonic multivalent functions of the form $f = h + \overline g$, satisfying ... More
Mass and Heat Diffusion in Ternary Polymer Solutions: A Classical Irreversible Thermodynamics ApproachJan 25 2016Apr 22 2016Governing equations for evolution of concentration and temperature in three-component systems were derived in the framework of classical irreversible thermodynamics using Onsager variational principle and were presented for solvent/solvent/polymer and ... More
Electronic Excitations and Stability of the Ground State of C60 MoleculesJul 09 1998A model study of the singlet excitons in the C60 molecule with emphasis on the Coulomb interaction between excited electron and hole leads to a physical understanding of the interaction effects on the absorption spectra and to a new identification of ... More
Data and Spectrum Trading Policies in a Trusted Cognitive Dynamic NetworkSep 24 2018Future wireless networks will progressively displace service provisioning towards the edge to accommodate increasing growth in traffic. This paradigm shift calls for smart policies to efficiently share network resources and ensure service delivery. In ... More
Congeniality Bounds on Quark Masses from NucleosynthesisDec 12 2012Jul 01 2013The work of Jaffe, Jenkins and Kimchi [Phys. Rev. D79, 065014 (2009)] is revisited to see if indeed the region of congeniality found in their analysis survives further restrictions from nucleosynthesis. It is observed that much of their congenial region ... More
Compact stars in Eddington-inspired Born-Infeld gravity: Anomalies associated with phase transitionsApr 02 2013Apr 09 2013We study how generic phase transitions taking place in compact stars constructed in the framework of the Eddington-inspired Born-Infeld (EiBI) gravity can lead to anomalous behavior of these stars. For the case with first-order phase transitions, compact ... More
On the stability of J$^*-$derivationsJul 16 2009In this paper, we establish the stability and superstability of $J^*-$derivations in $J^*-$algebras for the generalized Jensen--type functional equation $$rf(\frac{x+y}{r})+rf(\frac{x-y}{r})= 2f(x).$$ Finally, we investigate the stability of $J^*-$derivations ... More
Performance Enhancement of Ad Hoc Networks with Janitor Based RoutingApr 10 2012We propose and analyze a new on the fly strategy that discovers, repairs and maintains routes in hierarchical and distributed fashion called Janitor Based Routing (JBR). The main motivation behind our JBR protocol is to decrease flooding and routing overhead ... More
Effect of Interleaved FEC Code on Wavelet Based MC-CDMA System with Alamouti STBC in Different Modulation SchemesJul 17 2012In this paper, the impact of Forward Error Correction (FEC) code namely Trellis code with interleaver on the performance of wavelet based MC-CDMA wireless communication system with the implementation of Alamouti antenna diversity scheme has been investigated ... More
Testing universal relations of neutron stars with a nonlinear matter-gravity coupling theoryDec 04 2013Jan 13 2014Due to our ignorance of the equation of state (EOS) beyond nuclear density, there is still no unique theoretical model for neutron stars (NSs). It is therefore surprising that universal EOS-independent relations connecting different physical quantities ... More
Radial oscillations and stability of compact stars in Eddington-inspired Born-Infeld gravityAug 07 2012Sep 21 2012We study the hydrostatic equilibrium structure of compact stars in the Eddington-inspired Born-Infeld gravity recently proposed by Banados and Ferreira [Phys. Rev. Lett. 105, 011101 (2010)]. We also develop a framework to study the radial perturbations ... More
Performance of Stanford and Minipar Parser on Biomedical TextsSep 25 2014In this paper, the performance of two dependency parsers, namely Stanford and Minipar, on biomedical texts has been reported. The performance of te parsers to assignm dependencies between two biomedical concepts that are already proved to be connected ... More
Semi-supervised Classification for Natural Language ProcessingSep 25 2014Semi-supervised classification is an interesting idea where classification models are learned from both labeled and unlabeled data. It has several advantages over supervised classification in natural language processing domain. For instance, supervised ... More
Extracting Information-rich Part of Texts using Text DenoisingJul 30 2013The aim of this paper is to report on a novel text reduction technique, called Text Denoising, that highlights information-rich content when processing a large volume of text data, especially from the biomedical domain. The core feature of the technique, ... More
Iris Recognition Based on LBP and Combined LVQ ClassifierNov 07 2011Iris recognition is considered as one of the best biometric methods used for human identification and verification, this is because of its unique features that differ from one person to another, and its importance in the security field. This paper proposes ... More
Linking entanglement and quantum phase transitions via density functional theoryDec 04 2005Jan 09 2007Density functional theory (DFT) is shown to provide a novel conceptual and computational framework for entanglement in interacting many-body quantum systems. DFT can, in particular, shed light on the intriguing relationship between quantum phase transitions ... More
Sensitivity of stellar electron-capture rates to parent neutron number: A case study on a continuous chain of twenty Vanadium isotopesOct 22 2016Gamow-Teller (GT) strength distributions (B(GT)) in electron-capture (EC) daughters stemming from the parent ground state are computed with the shell-model in the full pf-shell space, with quasi-particle random-phase approximation (QRPA) in the formalism ... More
Design and Development of a Heart Rate Measuring Device using FingertipApr 09 2013In this paper, we presented the design and development of a new integrated device for measuring heart rate using fingertip to improve estimating the heart rate. As heart related diseases are increasing day by day, the need for an accurate and affordable ... More
Corpus-based Web Document Summarization using Statistical and Linguistic ApproachApr 09 2013Single document summarization generates summary by extracting the representative sentences from the document. In this paper, we presented a novel technique for summarization of domain-specific text from a single web document that uses statistical and ... More
A 2.0 Gb/s Throughput Decoder for QC-LDPC Convolutional CodesMay 01 2013This paper propose a decoder architecture for low-density parity-check convolutional code (LDPCCC). Specifically, the LDPCCC is derived from a quasi-cyclic (QC) LDPC block code. By making use of the quasi-cyclic structure, the proposed LDPCCC decoder ... More
Quarkonium dissociation at finite chemical potentialMar 27 2015Jul 24 2015We have studied the dissociation of quarkonia states in a deconfined medium of quarks and gluons at the large baryon chemical potential and small temperature region. The aim of this study is to probe the dense baryonic medium expected to be produced at ... More
Impact of Different Spreading Codes Using FEC on DWT Based MC-CDMA SystemJul 17 2012The effect of different spreading codes in DWT based MC-CDMA wireless communication system is investigated. In this paper, we present the Bit Error Rate (BER) performance of different spreading codes (Walsh-Hadamard code, Orthogonal gold code and Golay ... More
Multipolar universal relations between f-mode frequency and tidal deformability of compact starsAug 17 2014Jan 13 2015Though individual stellar parameters of compact stars usually demonstrate obvious dependence on the equation of state (EOS), EOS-insensitive universal formulas relating these parameters remarkably exist. In the present paper, we explore the interrelationship ... More
Non-local nuclear spin quieting in quantum dot molecules: Optically-induced extended two-electron spin coherence timeDec 15 2015We demonstrate the extension of coherence between all four two-electron spin ground states of an InAs quantum dot molecule (QDM) via non-local suppression of nuclear spin fluctuations in both constituent quantum dots (QDs), while optically addressing ... More
Photoluminescence and spectral switching of single CdSe/ZnS colloidal nanocrystals in poly(methyl methacrylate)Mar 30 2007Apr 08 2007Emission from single CdSe nanocrystals in PMMA was investigated. A fraction of the nanocrystals exhibiting switching between two energy states, which have similar total intensities, but distinctly different spectra were observed. We found that the spectral ... More
SibRank: Signed Bipartite Network Analysis for Neighbor-based Collaborative RankingJan 21 2016Apr 21 2016Collaborative ranking is an emerging field of recommender systems that utilizes users' preference data rather than rating values. Unfortunately, neighbor-based collaborative ranking has gained little attention despite its more flexibility and justifiability. ... More
I Have the Proof: Providing Proofs of Past Data Possession in Cloud ForensicsNov 19 2012Cloud computing has emerged as a popular computing paradigm in recent years. However, today's cloud computing architectures often lack support for computer forensic investigations. A key task of digital forensics is to prove the presence of a particular ... More
Graph-based Collaborative RankingApr 11 2016Sep 16 2016Collaborative ranking, is the new generation of collaborative filtering that focuses on users rankings rather than the ratings they give. Unfortunately, neighbor-based collaborative ranking has gained little attention since users have rarely common pairwise ... More
Upper-Bounding the Capacity of Relay Communications - Part IIApr 05 2014This paper focuses on the capacity of peer-to-peer relay communications wherein the transmitter are assisted by an arbitrary number of parallel relays, i.e. there is no link and cooperation between the relays themselves. We detail the mathematical model ... More
A Corpus-based Evaluation of Lexical Components of a Domainspecific Text to Knowledge Mapping PrototypeApr 28 2012The aim of this paper is to evaluate the lexical components of a Text to Knowledge Mapping (TKM) prototype. The prototype is domain-specific, the purpose of which is to map instructional text onto a knowledge domain. The context of the knowledge domain ... More
Development of a Conceptual Structure for a Domain-Specific CorpusApr 10 2012The corpus reported in this paper was developed for the evaluation of a domain-specific Text to Knowledge Mapping (TKM) prototype. The TKM prototype operates on the basis of both a combinatory categorical grammar (CCG) linguistic model and a knowledge ... More
Bottomonium suppression: A probe to the pre-equilibrium era of quark matterApr 24 2014We have studied the thermal suppression of the bottomonium states in relativistic heavy-ion collision at LHC energies as function of centrality, rapidity, transverse momentum etc. to explain the CMS data. Our investigation mainly spans over three problems: ... More
Upper-Bounding the Capacity of Relay Communications - Part IJan 11 2013This paper focuses on the capacity of point-to-point relay communications wherein the transmitter is assisted by an intermediate relay. We detail the mathematical model of cutset and amplify and forward (AF) relaying strategy. We present the upper bound ... More
Cloud Forensics: A Meta-Study of Challenges, Approaches, and Open ProblemsFeb 26 2013In recent years, cloud computing has become popular as a cost-effective and efficient computing paradigm. Unfortunately, today's cloud computing architectures are not designed for security and forensics. To date, very little research has been done to ... More
The Enemy Within: The Emerging Threats to Healthcare from Malicious Mobile DevicesOct 08 2012With the proliferation of wireless networks, mobile devices and medical devices are increasingly being equipped with wireless interfaces, such as Bluetooth and WiFi to allow easy access to and control of the medical devices. Unfortunately, the very presence ... More
Transmission of Voice Signal: BER Performance Analysis of Different FEC Schemes Based OFDM System over Various ChannelsJul 17 2012In this paper, we investigate the impact of Forward Error Correction (FEC) codes namely Cyclic Redundancy Code and Convolution Code on the performance of OFDM wireless communication system for speech signal transmission over both AWGN and fading (Rayleigh ... More
High multipole transitions in NIXS: valence and hybridization in 4f systemsDec 07 2007Momentum-transfer (q) dependent non-resonant inelastic x-ray scattering measurements were made at the N4,5 edges for several rare earth compounds. With increasing q, giant dipole resonances diminish, to be replaced by strong multiplet lines at lower energy ... More