Results for "Sandipan Sikdar"

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Time series analysis of temporal networksDec 04 2015An important feature of all real-world networks is that the network structure changes over time. Due to this dynamic nature, it becomes difficult to propose suitable growth models that can explain the various important characteristic properties of these ... More
StRE: Self Attentive Edit Quality Prediction in WikipediaJun 11 2019Wikipedia can easily be justified as a behemoth, considering the sheer volume of content that is added or removed every minute to its several projects. This creates an immense scope, in the field of natural language processing towards developing automated ... More
Using Core-Periphery Structure to Predict High Centrality Nodes in Time-Varying NetworksJun 20 2018Vertices with high betweenness and closeness centrality represent influential entities in a network. An important problem for time varying networks is to know a-priori, using minimal computation, whether the influential vertices of the current time step ... More
Influence of Reviewer Interaction Network on Long-term Citations: A Case Study of the Scientific Peer-Review System of the Journal of High Energy PhysicsMay 02 2017A `peer-review system' in the context of judging research contributions, is one of the prime steps undertaken to ensure the quality of the submissions received, a significant portion of the publishing budget is spent towards successful completion of the ... More
Bose Einstein Correlations in the Lund Model for Multijet SystemsNov 12 2002The interference based analysis of Bose Einstein Correlations in the Lund Model has hitherto been limited to simple strings without gluonic excitations. A new fragmentation method based on the Area Law in the Lund Model allows such an analysis to be extended ... More
Quantum double inclusions associated to a family of Kac algebra subfactorsJan 30 2019In \cite{Sde2018} we defined the notion of \textit{quantum double inclusion} associated to a finite-index and finite-depth subfactor and studied the quantum double inclusion associated to the Kac algebra subfactor $R^H \subset R$ where $H$ is a finite-dimensional ... More
Inflation with General Initial Conditions for Scalar PerturbationsOct 21 2011Mar 01 2012We explore the possibility of a single field quasi-de Sitter inflationary model with general initial state for primordial fluctuations. In this paper, first we compute the power spectrum and the bispectrum of scalar perturbations with coherent state as ... More
ComPAS: Community Preserving Sampling for Streaming GraphsFeb 05 2018In the era of big data, graph sampling is indispensable in many settings. Existing sampling methods are mostly designed for static graphs, and aim to preserve basic structural properties of the original graph (such as degree distribution, clustering coefficient ... More
Anomalies in the peer-review system: A case study of the journal of High Energy PhysicsAug 17 2016Peer-review system has long been relied upon for bringing quality research to the notice of the scientific community and also preventing flawed research from entering into the literature. The need for the peer-review system has often been debated as in ... More
Asymptotic Flatness and Quantum GeometrySep 20 2013Apr 08 2014We construct a canonical quantization of the two dimensional theory of a parametrized scalar field on noncompact spatial slices. The kinematics is built upon generalized charge-network states which are labelled by smooth embedding spacetimes, unlike the ... More
SU(2) gauge theory of gravity with topological invariantsOct 19 2011The most general gravity Lagrangian in four dimensions contains three topological densities, namely Nieh-Yan, Pontryagin and Euler, in addition to the Hilbert-Palatini term. We set up a Hamiltonian formulation based on this Lagrangian. The resulting canonical ... More
Quantum realizations of Hilbert-Palatini second-class constraintsNov 03 2009May 29 2010In a classical theory of gravity, the Barbero-Immirzi parameter ($\eta$) appears as a topological coupling constant through the Lagrangian density containing the Hilbert-Palatini term and the Nieh-Yan invariant. In a quantum framework, the topological ... More
Non-Gaussianity Consistency Relations, Initial States and Back-reactionNov 07 2013We explore the consistency relations for the three-point functions, in the squeezed limit, of scalar and tensor perturbations in single-field inflation with general initial conditions for the perturbations. For slow-roll inflation, we find that all the ... More
From a Kac algebra subfactor to Drinfeld doubleDec 12 2018Given a finite-index and finite-depth subfactor, we define the notion of \textit{quantum double inclusion} - a certain unital inclusion of von Neumann algebras constructed from the given subfactor - which is closely related to that of Ocneanu's asymptotic ... More
Quantum geometry with a nondegenerate vacuum: a toy modelJun 25 2013Sep 10 2013Motivated by a recent proposal (by Koslowski-Sahlmann) of a kinematical representation in Loop Quantum Gravity (LQG) with a nondegenerate vacuum metric, we construct a polymer quantization of the parametrised massless scalar field theory on a Minkowskian ... More
Gravity Asymptotics with Topological ParametersApr 29 2013Jul 26 2013In four dimensional gravity theory, the Barbero-Immirzi parameter has a topological origin, and can be identified as the coefficient multiplying the Nieh-Yan topological density in the gravity Lagrangian, as proposed by Date et al.[1]. Based on this fact, ... More
Dark Energy From The Gravity VacuumJan 05 2015Aug 09 2015We propose a new solution to the cosmological constant problem building on a nonperturbative quantum theory of gravity with torsional instantons. These pseudoparticles, which were recently found to exist in a first order formulation of Giddings-Strominger ... More
Classical Representation of a Quantum System at Equilibrium: ApplicationsNov 22 2012Feb 19 2013In the preceding paper, the structure and thermodynamics of a given quantum system was represented by a corresponding classical system having an effective temperature, local chemical potential, and pair potential. Here, that formal correspondence is implemented ... More
Steady-state Physics, Effective Temperature Dynamics in HolographyJul 24 2013Feb 25 2015Using the gauge-gravity duality, we argue that for a certain class of out-of-equilibrium steady-state systems in contact with a thermal background at a given temperature, the macroscopic physics can be captured by an effective thermodynamic description. ... More
Analysis and synthesis of nonlinear reversible cellular automata in linear timeNov 27 2013Cellular automata (CA) have been found as an attractive modeling tool for various applications, such as, pattern recognition, image processing, data compression, encryption, and specially for VLSI design & test. For such applications, mostly a special ... More
An Adaptive Training-less System for Anomaly Detection in Crowd ScenesJun 03 2019Anomaly detection in crowd videos has become a popular area of research for the computer vision community. Several existing methods generally perform a prior training about the scene with or without the use of labeled data. However, it is difficult to ... More
Taming Dirac strings and timelike loops in vacuum gravityFeb 20 2019The problem of singularities associated with Dirac strings and closed timelike curves in classical solutions of pure gravity is analyzed here. A method to eliminate these is introduced and established first for the Taub-NUT geometry. This is superceded ... More
Planar algebras, cabling and the Drinfeld doubleMar 24 2016We produce an explicit embedding of the planar algebra of the Drinfeld double of a finite-dimensional, semisimple and cosemisimple Hopf algebra $H$ into the two-cabling of the planar algebra of the dual Hopf algebra $H^*$ and characterise the image.
Inequivalence of fixed-force and fixed-extension statistical ensembles for a flexible polymer tethered to a planar substrateJul 27 2018Recent advances in single macromolecule experiments have sparked interest in the ensemble dependence of force-extension relations. The thermodynamic limit may not be attainable for such systems, that leads to inequivalence of the fixed-force and the fixed-extension ... More
Membrane Paradigm, Gravitational $Θ$-Term and Gauge/Gravity DualityDec 03 2015May 13 2016Following the membrane paradigm, we explore the effect of the gravitational $\Theta$-term on the behavior of the stretched horizon of a black hole in (3+1)-dimensions. We reformulate the membrane paradigm from a quantum path-integral point of view where ... More
A Species or Weak-Gravity Bound for Large $N$ Gauge Theories Coupled to GravityApr 19 2019Causality constrains the gravitational interactions of massive higher spin particles in both AdS and flat spacetime. We explore the extent to which these constraints apply to composite particles, explaining why they do not rule out macroscopic objects ... More
Physical Effects of the Gravitational $Θ$-ParameterDec 18 2016We describe the effect of the gravitational $\Theta$-parameter on the behavior of the stretched horizon of a black hole in $(3+1)$-dimensions. The gravitational $\Theta$-term is a total derivative, however, it affects the transport properties of the horizon. ... More
Effective Actions from Loop Quantum Cosmology: Correspondence with Higher Curvature GravityNov 25 2008Mar 30 2009Quantum corrections of certain types and relevant in certain regimes can be summarised in terms of an effective action calculable, in principle, from the underlying theory. The demands of symmetries, local form of terms and dimensional considerations ... More
Folding thermodynamics of peptidesDec 03 2004A simplified interaction potential for protein folding studies at the atomic level is discussed and tested on a set of peptides with about 20 residues each. The test set contains both alpha-helical (Trp cage, Fs) and beta-sheet (GB1p, GB1m2, GB1m3, Betanova, ... More
Classical Model for JelliumFeb 19 2013A simple, practical model for computing the equilibrium thermodynamics and structure of jellium by classical strong coupling methods is proposed. An effective pair potential and coupling constant are introduced, incorporating the ideal gas, low density, ... More
Hall Scrambling on Black Hole HorizonsJan 06 2015Aug 31 2015We explore the effect of the electrodynamics $\theta$-angle on the macroscopic properties of black hole horizons. Using only classical Einstein-Maxwell-Chern-Simons theory in (3+1)-dimensions, in the form of the membrane paradigm, we show that in the ... More
Note on infinite iterated crossed products of Hopf algebras and the Drinfeld doubleMar 18 2015For a finite dimensional Hopf algebra we show that an associated natural inclusion of infinite crossed products is the crossed product by the Drinfeld double, and that this is a characterisation of the double.
Classical Representation of a Quantum System at Equilibrium: TheoryNov 22 2012Feb 19 2013A quantum system at equilibrium is represented by a corresponding classical system, chosen to reproduce thermodynamic and structural properties. The motivation is to allow application of classical strong coupling theories and molecular dynamics simulation ... More
Strongly Coupled Gauge Theories: High and Low Temperature Behavior of Non-local ObservablesDec 11 2012Apr 24 2013We explore the high and low temperature behavior of non-local observables in strongly coupled gauge theories that are dual to AdS. We develop a systematic expansion for equal time two-point correlation, spatial Wilson loops and entanglement entropy at ... More
Degenerate spacetimes in first order gravityFeb 15 2016Apr 23 2016We present a systematic framework to obtain the most general solutions of the equations of motion in first order gravity theory with degenerate tetrads. There are many possible solutions. Generically, these exhibit non-vanishing torsion even in the absence ... More
Spin Filtering through Single-Wall Carbon Nanotubes Functionalized with Single-Stranded DNAJun 26 2016High spin polarization materials or spin filters are key components in spintronics, a niche subfield of electronics where carrier spins play a functional role. Carrier transmission through these materials is "spin selective" i.e. these materials are able ... More
Strong coupling electrostatic theory of polymer counterions close to planar chargesNov 11 2015Strong coupling phenomena, such as the like charged macroions attraction, opposite charged macroions repulsion, charge renormalization or charge inversion, are known to be mediated by multivalent counterions. Most theories treat the counterions as point ... More
Adsorption of highly charged Gaussian polyelectrolytes to oppositely charged surfacesNov 16 2015In many biological processes highly charged biomolecules are adsorbed into oppositely charged surfaces of macroions and membranes. They form strongly correlated structures close to the surface which can not be explained by the conventional Poisson-Boltzmann ... More
Classical Representation of a Quantum System at EquilibriumOct 12 2011A quantum system at equilibrium is represented by a corresponding classical system, chosen to reproduce the thermodynamic and structural properties. The objective is to develop a means for exploiting strong coupling classical methods (e.g., MD, integral ... More
Aspects of Holographic Entanglement at Finite Temperature and Chemical PotentialFeb 23 2016We investigate the behavior of entanglement entropy at finite temperature and chemical potential for strongly coupled large-N gauge theories in $d$-dimensions ($d\ge 3$) that are dual to Anti-de Sitter-Reissner-Nordstrom geometries in $(d+1)-$dimensions, ... More
New solutions in pure gravity with degenerate tetradsSep 08 2016Nov 01 2016In first order formulation of pure gravity, we find a new class of solutions to the equations of motion represented by degenerate four-geometries. These configurations are described by non- invertible tetrads with two zero eigenvalues and admit non-vanishing ... More
Multiple Changepoint Estimation in High-Dimensional Gaussian Graphical ModelsDec 15 2017We consider the consistency properties of a regularised estimator for the simultaneous identification of both changepoints and graphical dependency structure in multivariate time-series. Traditionally, estimation of Gaussian Graphical Models (GGM) is ... More
Spread of entanglement for small subsystems in holographic CFTsFeb 18 2016Mar 28 2017We develop an analytic perturbative expansion to study the propagation of entanglement entropy for small subsystems after a global quench, in the context of the AdS/CFT correspondence. Opposite to the large interval limit, in this case the evolution of ... More
Signature of nonexponential nuclear decayMar 18 2015Precision tests of decay law of radioactive nuclei have not so far found any deviation from the exponential decay law at early time, as predicted by quantum mechanics. In this paper, we show that the quantum decoherence time (i.e. the timescale of nonexponential ... More
New solutions in pure gravity with degenerate tetradsSep 08 2016In first order formulation of pure gravity, we find a new class of solutions to the equations of motion represented by degenerate four-geometries. These configurations are described by non- invertible tetrads with two zero eigenvalues and admit non-vanishing ... More
Canonical supergravity with Barbero-Immirzi parameterSep 26 2009A canonical formulation of the N=1 supergravity theory containing the topological Nieh-Yan term in its Lagrangian density is developed. The constraints are analysed without choosing any gauge. In the time gauge, the theory is shown to be described in ... More
Torsional instanton effects in quantum gravityNov 18 2014Jan 05 2015We show that, in the first order gravity theory coupled to axions, the instanton number of the Giddings-Strominger wormhole can be interpreted as the Nieh-Yan topological index. The axion charge of the baby universes is quantized in terms of the Nieh-Yan ... More
Spin Transport in Organic Semiconductors: A Brief Overview of the First Eight YearsMay 07 2010In this article we briefly review the current state of the experimental research on spin polarized transport in organic semiconductors. These systems, which include small molecular weight compounds and polymers, are central in the rapidly maturing area ... More
Shell formation in short like-charged polyelectrolytes in a harmonic trapNov 12 2015Feb 02 2016Inspired by recent experiments and simulations on pattern formation in biomolecules by optical tweezers, a theoretical description based on reference interaction site model (RISM) integral equation method is developed to calculate the equilibrium density ... More
Spread of entanglement for small subsystems in holographic CFTsFeb 18 2016We develop an analytic perturbative expansion to study the propagation of entanglement entropy for small subsystems after a global quench, in the context of the AdS/CFT correspondence. Opposite to the large interval limit, in this case the evolution of ... More
Topological parameters in gravityJun 15 2011Jun 20 2011We present the Hamiltonian analysis of the theory of gravity based on a Lagrangian density containing Hilbert-Palatini term along with three topological densities, Nieh-Yan, Pontryagin and Euler. The addition of these topological terms modifies the symplectic ... More
The Lund Fragmentation Process for a Multi-gluon String According to the Area LawJun 16 2001The Lund Area Law describes the probability for the production of a set of colourless hadrons from an initial set of partons, in the Lund string fragmentation model. In this paper we will present a general method to implement the Area Law for a multi-gluon ... More
Oligomerization of amyloid Abeta peptides using hydrogen bonds and hydrophobicity forcesSep 01 2004Sep 14 2004The 16-22 amino acid fragment of the beta-amyloid peptide associated with the Alzheimer's disease, Abeta, is capable of forming amyloid fibrils. Here we study the aggregation mechanism of Abeta(16-22) peptides by unbiased thermodynamic simulations at ... More
Bundle formation in parallel aligned polymers with competing interactionsNov 12 2015Apr 29 2016Aggregation of like-charged polymers is widely observed in biological and soft matter systems. In many systems, bundles are formed when a short-range attraction of diverse physical origin like charge-bridging, hydrogen-bonding or hydrophobic interaction, ... More
Entangled polymer complex as Higgs phenomenaApr 16 2015Apr 17 2015We derive an effective Maxwell-London equation for entangled polymer complex under the topological constraint, borrowing the theoretical framework from the topological field theory. We find that the transverse current flux of the test polymer chain, surrounded ... More
Mechanism Design for Multi-Type Housing MarketsNov 23 2016We study multi-type housing markets, where there are $p\ge 2$ types of items, each agent is initially endowed one item of each type, and the goal is to design mechanisms without monetary transfer to (re)allocate items to the agents based on their preferences ... More
Solving Dominating Set in Larger Classes of Graphs: FPT Algorithms and Polynomial KernelsMar 26 2009May 15 2009We show that the k-Dominating Set problem is fixed parameter tractable (FPT) and has a polynomial kernel for any class of graphs that exclude K_{i,j} as a subgraph, for any fixed i, j >= 1. This strictly includes every class of graphs for which this problem ... More
Linear-Time Algorithms for Graphs of Bounded Rankwidth: A Fresh Look Using Game TheoryFeb 04 2011We present an alternative proof of a theorem by Courcelle, Makowski and Rotics which states that problems expressible in MSO are solvable in linear time for graphs of bounded rankwidth. Our proof uses a game-theoretic approach and has the advantage of ... More
Emergent Horizons and Causal Structures in HolographyMay 24 2016The open string metric arises kinematically in studying fluctuations of open string degrees of freedom on a D-brane. An observer, living on a probe D-brane, can send signals through the spacetime by using such fluctuations on the probe, that propagate ... More
A Bound on Massive Higher Spin ParticlesNov 05 2018Dec 27 2018According to common lore, massive elementary higher spin particles lead to inconsistencies when coupled to gravity. However, this scenario was not completely ruled out by previous arguments. In this paper, we show that in a theory where the low energy ... More
Topological Interpretation of Barbero-Immirzi ParameterNov 27 2008Dec 04 2008We set up a canonical Hamiltonian formulation for a theory of gravity based on a Lagrangian density made up of the Hilbert-Palatini term and, instead of the Holst term, the Nieh-Yan topological density. The resulting set of constraints in the time gauge ... More
Markov modeling of peptide folding in the presence of protein crowdersJan 29 2018We use Markov state models (MSMs) to analyze the dynamics of a $\beta$-hairpin-forming peptide in Monte Carlo (MC) simulations with interacting protein crowders, for two different types of crowder proteins [bovine pancreatic trypsin inhibitor (BPTI) and ... More
An effective all-atom potential for proteinsApr 08 2009We describe and test an implicit solvent all-atom potential for simulations of protein folding and aggregation. The potential is developed through studies of structural and thermodynamic properties of 17 peptides with diverse secondary structure. Results ... More
Improving Performance of Speaker Identification System Using Complementary Information FusionMay 13 2011May 16 2011Feature extraction plays an important role as a front-end processing block in speaker identification (SI) process. Most of the SI systems utilize like Mel-Frequency Cepstral Coefficients (MFCC), Perceptual Linear Prediction (PLP), Linear Predictive Cepstral ... More
Higher significance with smaller samples: A modified Sequential Probability Ratio TestNov 20 2018We describe a modified sequential probability ratio test that can be used to reduce the average sample size required to perform statistical hypothesis tests at specified levels of significance and power. Examples are provided for Z-tests, T-Tests, and ... More
Likelihood Inference for Large Scale Stochastic Blockmodels with Covariates based on a Divide-and-Conquer Parallelizable Algorithm with CommunicationOct 30 2016Aug 07 2018We consider a stochastic blockmodel equipped with node covariate information, that is helpful in analyzing social network data. The key objective is to obtain maximum likelihood estimates of the model parameters. For this task, we devise a fast, scalable ... More
Finite Temperature Quantum Effects on Confined ChargesJun 01 2016A quantum system of N Coulomb charges confined within a harmonic trap is considered over a wide range of densities and temperatures. A recently described construction of an equivalent classical system is applied in order to exploit the rather complete ... More
A Conformal Collider for Holographic CFTsMay 18 2018Dec 14 2018We develop a formalism to study the implications of causality on OPE coefficients in conformal field theories with large central charge and a sparse spectrum of higher spin operators. The formalism has the interpretation of a new conformal collider-type ... More
Bulk Matter and the Boundary Quantum Null Energy ConditionMar 11 2018We investigate the quantum null energy condition (QNEC) in holographic CFTs, focusing on half-spaces and particular classes of states. We present direct, and in certain cases nonperturbative, calculations for both the diagonal and off- diagonal variational ... More
A New Spin on Causality ConstraintsJan 28 2016Causality in a shockwave state is related to the analytic properties of a four-point correlation function. Extending recent results for scalar probes, we show that this constrains the couplings of the stress tensor to light spinning operators in conformal ... More
Causality Constraints in Conformal Field TheoryAug 31 2015Aug 03 2016Causality places nontrivial constraints on QFT in Lorentzian signature, for example fixing the signs of certain terms in the low energy Lagrangian. In d-dimensional conformal field theory, we show how such constraints are encoded in crossing symmetry ... More
Embedding Secret Data in HTML Web PageApr 03 2010In this paper, we suggest a novel data hiding technique in an HTML Web page. HTML Tags are case insensitive and hence an alphabet in lowercase and one in uppercase present inside an HTML tag are interpreted in the same manner by the browser,i.e., change ... More
A Very Simple Approach for 3-D to 2-D MappingMar 21 2010Many times we need to plot 3-D functions e.g., in many scientificc experiments. To plot this 3-D functions on 2-D screen it requires some kind of mapping. Though OpenGL, DirectX etc 3-D rendering libraries have made this job very simple, still these libraries ... More
Spin relaxation of "upstream" electrons in quantum wires: Failure of the drift diffusion modelFeb 09 2006The classical drift diffusion (DD) model of spin transport treats spin relaxation via an empirical parameter known as the ``spin diffusion length''. According to this model, the ensemble averaged spin of electrons drifting and diffusing in a solid decays ... More
Spin transport in self assembled all-metal nanowire spin valves: A study of the pure Elliott-Yafet mechanismNov 01 2005We report experimental study of spin transport in all-metal nanowire spin valve structures. The nanowires have a diameter of 50 nm and consist of three layers - cobalt, copper and nickel. Based on the experimental observations, we conclude that the primary ... More
Construction of Learning Path Using Ant Colony Optimization from a Frequent Pattern GraphJan 19 2012In an e-Learning system a learner may come across multiple unknown terms, which are generally hyperlinked, while reading a text definition or theory on any topic. It becomes even harder when one tries to understand those unknown terms through further ... More
Flavour Fields in Steady State: Stress Tensor and Free EnergyDec 17 2015The dynamics of a probe brane in a given gravitational background is governed by the Dirac-Born-Infeld action. The corresponding open string metric arises naturally in studying the fluctuations on the probe. In Gauge-String duality, it is known that in ... More
Holographic Entanglement in a Noncommutative Gauge TheoryJul 10 2013Jan 28 2014In this article we investigate aspects of entanglement entropy and mutual information in a large-N strongly coupled noncommutative gauge theory, both at zero and at finite temperature. Using the gauge-gravity duality and the Ryu-Takayanagi (RT) prescription, ... More
Holographic Mutual Information at Finite TemperatureDec 19 2012Jul 08 2013Using the Ryu-Takayanagi conjectured formula for entanglement entropy in the context of gauge-gravity duality, we investigate properties of mutual information between two disjoint rectangular sub-systems in finite temperature relativistic conformal field ... More
Hedging parameter selection for basis pursuitMay 04 2018In Compressed Sensing and high dimensional estimation, signal recovery often relies on sparsity assumptions and estimation is performed via $\ell_1$-penalized least-squares optimization, a.k.a. LASSO. The $\ell_1$ penalisation is usually controlled by ... More
Likelihood Inference for Large Scale Stochastic Blockmodels with Covariates based on a Divide-and-Conquer Parallelizable Algorithm with CommunicationOct 30 2016We consider a stochastic blockmodel equipped with node covariate information, that is useful in analyzing social network data. The objective is to obtain maximum likelihood estimates of the model parameters. For this task, we devise a fast, scalable Monte ... More
Hiding Inside HTML and Other Source CodesMar 17 2010Many steganographic techniques were proposed for hiding secret message inside images, the simplest of them being the LSB data hiding. In this paper, we suggest a novel data hiding technique in an HTML Web page and also propose some simple techniques to ... More
The Lambda-Measure and the Generalised Dipoles in the Lund ModelJul 01 2002We demonstrate that the multiple gluon emission phase space in the dipole cascade model has a strong linear correlation with the number of gluons emitted. The number of gluons per unit available phase space at a certain resolution scale is found to be ... More
Recent Developments in the Lund ModelDec 09 2002A brief introduction to the String Fragmentation Model and its consequences is presented. We discuss the fragmentation of a general multi-gluon string and show that it can be formulated as the production of a set of ''plaquettes'' between the hadronic ... More
User Satisfaction-Driven Bandwidth Allocation for Image Transmission in a Crowded EnvironmentFeb 25 2018A major portion of postings on social networking sites constitute high quality digital images and videos. These images and videos require a fairly large amount of bandwidth during transmission. Accordingly, high quality image and video postings become ... More
Finite Temperature Quantum Effects in Many-body Systems by Classical MethodsFeb 02 2015Apr 10 2015A recent description of an exact map for the equilibrium structure and thermodynamics of a quantum system onto a corresponding classical system is summarized. Approximate implementations are constructed by pinning exact limits (ideal gas, weak coupling), ... More
Spin relaxation of "upstream" electrons: beyond the drift diffusion modelNov 01 2005The classical drift diffusion (DD) model of spin transport treats spin relaxation via an empirical parameter known as the ``spin diffusion length''. According to this model, the ensemble averaged spin of electrons drifting and diffusing in a solid decays ... More
An LSB Data Hiding Technique Using Prime NumbersMar 29 2010In this paper, a novel data hiding technique is proposed, as an improvement over the Fibonacci LSB data-hiding technique proposed by Battisti et al. First we mathematically model and generalize our approach. Then we propose our novel technique, based ... More
An LSB Data Hiding Technique Using Natural NumbersMar 21 2010In this paper, a novel data hiding technique is proposed, as an improvement over the Fibonacci LSB data-hiding technique proposed by Battisti et al,based on decomposition of a number (pixel-value) in sum of natural numbers. This particular representation ... More
Effective potentials in polyelectrolyte solutionsJan 07 2016Using Poisson-Boltzmann equation and linear response theory, we derive an effective interaction potential due to a fixed charge distribution in a solution containing polyelectrolytes and point salt. We obtain an expression for the effective potential ... More
Averaged Null Energy Condition from CausalityOct 17 2016Unitary, Lorentz-invariant quantum field theories in flat spacetime obey microcausality: commutators vanish at spacelike separation. For interacting theories in more than two dimensions, we show that this implies that the averaged null energy, $\int du ... More
Entanglement and out-of-equilibrium dynamics in holographic models of de Sitter QFTsNov 21 2013Jul 07 2014In this paper we study various aspects of entanglement entropy in strongly-coupled de Sitter quantum field theories in various dimensions. We find gravity solutions that are dual to field theories in a fixed de Sitter background, both in equilibrium and ... More
Back-reaction of Non-supersymmetric Probes: Phase Transition and StabilityAug 13 2012Aug 31 2012We consider back-reaction by non-supersymmetric D7/anti-D7 probe branes in the Kuperstein-Sonnenschein model at finite temperature. Using the smearing technique, we obtain an analytical solution for the back-reacted background to leading order in N_f/N_c. ... More
Change-Point Estimation in High-Dimensional Markov Random Field ModelsMay 23 2014Dec 25 2015This paper investigates a change-point estimation problem in the context of high-dimensional Markov Random Field models. Change-points represent a key feature in many dynamically evolving network structures. The change-point estimate is obtained by maximizing ... More
Fast Biclustering by Dual ParameterizationJul 29 2015We study two clustering problems, Starforest Editing, the problem of adding and deleting edges to obtain a disjoint union of stars, and the generalization Bicluster Editing. We show that, in addition to being NP-hard, none of the problems can be solved ... More
Linear Kernels on Graphs Excluding Topological MinorsJan 13 2012Jul 13 2012We show that problems which have finite integer index and satisfy a requirement we call treewidth-bounding admit linear kernels on the class of $H$-topological-minor free graphs, for an arbitrary fixed graph $H$. This builds on earlier results by Fomin ... More
Fully Dense UNet for 2D Sparse Photoacoustic Tomography Artifact RemovalAug 31 2018Sep 10 2018Photoacoustic imaging is an emerging imaging modality that is based upon the photoacoustic effect. In photoacoustic tomography (PAT), the induced acoustic pressure waves are measured by an array of detectors and used to reconstruct an image of the initial ... More
Data Hiding Techniques Using Prime and Natural NumbersMar 18 2010In this paper, a few novel data hiding techniques are proposed. These techniques are improvements over the classical LSB data hiding technique and the Fibonacci LSB data-hiding technique proposed by Battisti et al. \cite{r1}. The classical LSB technique ... More
Green function of correlated genes in a minimal mechanical model of protein evolutionJan 11 2018May 01 2018The function of proteins arises from cooperative interactions and rearrangements of their amino acids, which exhibit large-scale dynamical modes. Long-range correlations have also been revealed in protein sequences, and this has motivated the search for ... More