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Results for "Rahul Ramesh"

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Successor Options: An Option Discovery Framework for Reinforcement LearningMay 14 2019The options framework in reinforcement learning models the notion of a skill or a temporally extended sequence of actions. The discovery of a reusable set of skills has typically entailed building options, that navigate to bottleneck states. This work ... More
Dileptons from $η_c$ in Nucleus-Nucleus collisionsSep 19 2000Oct 20 2000Preliminary estimates suggest that excess dimuon production with invariant mass in the range 1.5 -- 2.5 GeV in nucleus-nucleus collisions can be explained on the basis of $\eta_c$ production. This appears to be consistent with all the peripheral and central ... More
Superfluid, Mott-Insulator, and Mass-Density-Wave Phases in the One-Dimensional Extended Bose-Hubbard ModelJul 01 2004We use the finite-size density-matrix-renormalization-group (FSDMRG) method to obtain the phase diagram of the one-dimensional ($d = 1$) extended Bose-Hubbard model for density $\rho = 1$ in the $U-V$ plane, where $U$ and $V$ are, respectively, onsite ... More
Phases and Transitions in the Spin-1 Bose-Hubbard Model: Systematics of a Mean-field TheoryMay 15 2007We generalize the mean-field theory for the spinless Bose-Hubbard model to account for the different types of superfluid phases that can arise in the spin-1 case. In particular, our mean-field theory can distinguish polar and ferromagnetic superfluids, ... More
BOLA: Near-Optimal Bitrate Adaptation for Online VideosJan 25 2016Apr 12 2016Modern video players employ complex algorithms to adapt the bitrate of the video that is shown to the user. Bitrate adaptation requires a tradeoff between reducing the probability that the video freezes and enhancing the quality of the video shown to ... More
K_1 of products of Drinfeld modular curves and special values of L-functionsSep 03 2009Beilinson obtained a formula relating the special value of the L-function of H^2 of a product of modular curves to the regulator of an element of a motivic cohomology group - thus providing evidence for his general conjectures on special values of L-functions. ... More
Hydrodynamic Drag on a Compact Star Orbiting a Supermassive Black HoleJul 23 1999The proposed Laser Interferometer Space Antenna is expected to detect gravitational waves from neutron stars and stellar-mass black holes spiraling into supermassive black holes in distant galactic nuclei. Analysis of the inspiral events will require ... More
Advection-Dominated Accretion Flows: Optically Thin SolutionsDec 09 1995General properties of advection-dominated accretion flows are discussed. Special emphasis is given to the optically thin branch of solutions, which has very high ion and electron temperatures and is thermally stable. This solution branch has been applied ... More
Why Do AGN Lighthouses Switch Off?Jan 15 2002Nearby galactic nuclei are observed to be very much dimmer than active galactic nuclei in distant galaxies. The Chandra X-ray Observatory has provided a definitive explanation for why this is so. With its excellent angular resolution, Chandra has imaged ... More
Homotopy Inertia Groups and Tangential StructuresNov 12 2015May 25 2017We show that if $M$ and $N$ have the same homotopy type of simply connected closed smooth $m$-manifolds such that the integral and mod-$2$ cohomologies of $M$ vanish in odd degrees, then their homotopy inertia groups are equal. Let $M^{2n}$ be a closed ... More
Relations among Heegner Cycles on families of abelian surfacesMay 16 2000We compute relations of rational equivalence among special codimensional two cycles on families of abelian surfaces using elements of higher chow groups.
Higher order modular forms and mixed Hodge theorySep 03 2009Sep 07 2009In this paper we introduce a certain space of higher order modular forms of weight 0 and show that it has a Hodge structure coming from the geometry of the fundamental group of a modular curve. This generalizes the usual structure on classical weight ... More
Higher Chow Cycles on an Abelian Surface and a non-Archimedean analogue of the Hodge-D-conjectureFeb 08 2011Aug 30 2013We construct new indecomposable elements in the higher Chow group CH2(A,1) of a principally polarized Abelian surface over a non Archimedean local field, which generalize an element constructed by Collino. These elements are constructed using a generalization, ... More
Coreset-Based Adaptive TrackingNov 19 2015We propose a method for learning from streaming visual data using a compact, constant size representation of all the data that was seen until a given moment. Specifically, we construct a 'coreset' representation of streaming data using a parallelized ... More
Phases, transitions, and patterns in the one-dimensional Extended Bose-Hubbard modelMar 10 2014We carry out an extensive study of the phase diagram of the extended Bose Hubbard model, with a mean filling of one boson per site, in one dimension by using the density matrix renormalization group and show that it can have Superfluid (SF), Mott-insulator ... More
Phases, transitions, and boundary conditions in a model of interacting bosonsNov 22 2012We carry out an extensive study of the phase diagrams of the extended Bose Hubbard model, with a mean filling of one boson per site, in one dimension by using the density matrix renormalization group and show that it contains Superfluid (SF), Mott-insulator ... More
Random-Phase-Approximation Excitation Spectra for Bose-Hubbard ModelsOct 14 2014We obtain the excitation spectra of the following three generalized Bose-Hubbard (BH) models: (1) a two-species generalization of the spinless BH model, (2) a single-species, spin-1 BH model, and (3) the extended Bose-Hubbard model (EBH) for spinless ... More
The Inhomogeneous Extended Bose-Hubbard Model: A Mean-Field TheoryJan 31 2012We develop an inhomogeneous mean-field theory for the extended Bose-Hubbard model with a quadratic, confining potential. In the absence of this potential, our mean-field theory yields the phase diagram of the homogeneous extended Bose-Hubbard model. This ... More
Learning to Factor Policies and Action-Value Functions: Factored Action Space Representations for Deep Reinforcement learningMay 20 2017Deep Reinforcement Learning (DRL) methods have performed well in an increasing numbering of high-dimensional visual decision making domains. Among all such visual decision making problems, those with discrete action spaces often tend to have underlying ... More
Bose-Hubbard Models in Confining Potentials: An Inhomogeneous Mean-Field TheoryJan 08 2012We present an extensive study of Mott insulator (MI) and superfluid (SF) shells in Bose-Hubbard (BH) models for bosons in optical lattices with harmonic traps. For this we develop an inhomogeneous mean-field theory. Our results for the BH model with one ... More
AUPCR Maximizing Matchings : Towards a Pragmatic Notion of Optimality for One-Sided Preference MatchingsNov 27 2017Nov 28 2017We consider the problem of computing a matching in a bipartite graph in the presence of one-sided preferences. There are several well studied notions of optimality which include pareto optimality, rank maximality, fairness and popularity. In this paper, ... More
HERA Physics - an overview of experimental and theoretical resultsMay 19 1997In this talk I review the low x QCD experimental results from HERA and their theoretical underpinnings. In particular, I discuss the structure function $F_2$, large rapidity gap events, pomeron structure functions and $J/\psi$ production.
Sentiment Analysis: A SurveyMay 11 2014Sentiment analysis (also known as opinion mining) refers to the use of natural language processing, text analysis and computational linguistics to identify and extract subjective information in source materials. Mining opinions expressed in the user generated ... More
Many body localization and delocalization in the two dimensional continuumAug 26 2014I discuss whether localization in the two dimensional continuum can be stable in the presence of short range interactions. I conclude that, for an impurity model of disorder, if the system is prepared below a critical temperature $T < T_c$, then perturbation ... More
Prediction and description of a chiral pseudogap phaseApr 22 2012We point out that a system which supports chiral superconductivity should also support a chiral pseudogap phase: a finite temperature phase wherein superconductivity is lost but time reversal symmetry is still broken. This chiral pseudogap phase can be ... More
Combined effect of horizontal magnetic field and vorticity on Rayleigh Taylor instabilityAug 06 2016In this research, the height, curvature and velocity of the bubble tip in Rayleigh-Taylor instability at arbitrary Atwood number with horizontal magnetic field are investigated. To support the earlier simulation and experimental results, the vorticity ... More
A Model for Dipole Modulation of CMBR PolarizationAug 13 2015Oct 05 2015I propose a model of dipole modulation in Cosmic Background Microwave Radiation (CMBR) polarization fields Q and U. It is shown that the modulation leads to correlations between l and l multipoles where either l = l or l = l \pm 1, but the contribution ... More
A New Push-Relabel Algorithm for Sparse NetworksOct 29 2013Jun 10 2014In this paper, we present a new push-relabel algorithm for the maximum flow problem on flow networks with $n$ vertices and $m$ arcs. Our algorithm computes a maximum flow in $O(mn)$ time on sparse networks where $m = O(n)$. To our knowledge, this is the ... More
Rational curves on hypersurfaces [after A. Givental]Jun 23 1998This article accompanies my June 1998 seminaire Bourbaki talk on Givental's work. After a quick review of descendent integrals in Gromov-Witten theory, I discuss Givental's formalism relating hypergeometric series to solutions of quantum differential ... More
WW Fusion in Higgsless ModelsNov 30 2006Jan 31 2007Recently several Higgsless models of electroweak symmetry breaking have been proposed in which unitarity of $W,Z$ scattering amplitudes is partially restored through a tower of massive vector gauge bosons. These massive states are expected to couple mainly ... More
Signatures of New Physics from HBT Correlations in UHECRsJan 11 2012Sep 04 2012Quantum fields written on noncommutative spacetime (Groenewold - Moyal plane) obey twisted commutation relations. In this paper we show that these twisted commutation relations result in Hanbury-Brown Twiss (HBT) correlations that are distinct from that ... More
2048 is (PSPACE) Hard, but Sometimes EasyAug 27 2014We prove that a variant of 2048, a popular online puzzle game, is PSPACE-Complete. Our hardness result holds for a version of the problem where the player has oracle access to the computer player's moves. Specifically, we show that for an $n \times n$ ... More
Two-dimensional Sentiment Analysis of textJun 08 2014Sentiment Analysis aims to get the underlying viewpoint of the text, which could be anything that holds a subjective opinion, such as an online review, Movie rating, Comments on Blog posts etc. This paper presents a novel approach that classify text in ... More
A geometric construction of Getzler's relationMay 17 1997A geometric construction of Getzler's cohomological relation in the moduli space of 4 pointed elliptic curves is given by a push-forward of a natural rational equivalence in a space of admissible covers. In particular, Getzler's relation is shown to be ... More
Space group symmetries and low lying excitations of many-body systems at integer fillingsDec 12 2012We show that many-body systems with conserved particle number which have the symmetries corresponding to a nonsymmorphic space group have low lying excitations for certain integer values of the particle number per unit cell. These results may be interpreted ... More
Characterization of 3d topological insulators by 2d invariantsApr 20 2010The prediction of non-trivial topological phases in Bloch insulators in three dimensions has recently been experimentally verified. Here, I provide a picture for obtaining the $Z_{2}$ invariants for a three dimensional topological insulator by deforming ... More
Topological invariants of time reversal invariant superconductorsAug 02 2006The topological invariants of gapped time reversal invariant lattice superconductors are studied by mapping the superconducting mean field Hamiltonian to a Bloch Hamiltonian. There is a single $Z_2 $ invariant in two dimensions and four such invariants ... More
Topological pumps and adiabatic cyclesApr 11 2011Topological insulators have gapless states at their boundaries while trivial insulators generically do not. We consider loops in the spaces of Hamiltonians of topologically trivial Bloch insulators, and show that there exist loops for which the boundary ... More
The generalized modified Bessel function $K_{z,w}(x)$ at $z=1/2$ and Humbert functionsOct 07 2018Recently Dixit, Kesarwani, and Moll introduced a generalization $K_{z,w}(x)$ of the modified Bessel function $K_{z}(x)$ and showed that it satisfies an elegant theory similar to $K_{z}(x)$. In this paper, we show that while $K_{\frac{1}{2}}(x)$ is an ... More
Coverage of space in Boolean modelsAug 10 2006For a marked point process $\{(x_i,S_i)_{i\geq 1}\}$ with $\{x_i\in \Lambda:i\geq 1\}$ being a point process on $\Lambda \subseteq \mathbb{R}^d$ and $\{S_i\subseteq R^d:i\geq 1\}$ being random sets consider the region $C=\cup_{i\geq 1}(x_i+S_i)$. This ... More
Implications of CKM Unitarity on the search for New Physics in B meson decaysDec 22 2008Dec 30 2008This paper has been temporarily withdrawn by the author. A modified version will be resubmitted. One of the trivial solutions was missed with crucial bearing on conclusions.
Max-Flows on Sparse and Dense NetworksSep 10 2013Oct 29 2013In this paper, we present an improved algorithm for the maximum flow problem on general networks with $n$ vertices and $m$ arcs. We show how to solve the problem in $O(mn)$ time, when $m = O(n^{2-\epsilon})$, for some $0 <\epsilon \leq 1$. This improves ... More
Conormal Varieties on the Cominuscule Grassmannian - IIMay 31 2018Sep 24 2018Let $X_w$ be a Schubert subvariety of a cominuscule Grassmannian $X$, and let $\mu:T^*X\rightarrow\mathcal N$ be the Springer map from the cotangent bundle of $X$ to the nilpotent cone $\mathcal N$. In this paper, we construct a resolution of singularities ... More
Can there be a heavy sbottom hidden in three-jet data at LEP?Jun 20 2003Nov 18 2003A low-energy supersymmetry scenario with a light gluino of mass 12 - 16 GeV and light sbottom (b1) of mass 2 - 6 GeV has been used to explain the apparent overproduction of b quarks at the Tevatron. In this scenario the other mass eigenstate of the sbottom, ... More
Non-power-law relaxation in A-B annihilation with exclusionFeb 17 2016We explore the effect of initial conditions on the decay of the reaction $A+B \rightarrow \phi$ in one dimension, with exclusion interaction between particles. It is well-known that the late-time density of surviving particles goes as $t^{-1/4}$ with ... More
Three dimensional topological invariants for time reversal invariant Hamiltonians and the three dimensional quantum spin Hall effectJul 20 2006Jul 21 2006The $Z_2$ invariant for filled bands in the ground states of systems with time reversal invariance characterizes the number of stable pairs of edge states. Here we study the $Z_2 $ invariant using band touching methods discussed in a recent previous work ... More
Integer Quantum Hall Effect on a Square Lattice with Zero Net Magnetic FieldMar 09 2006A square lattice model which exhibits a nonzero quantized Hall conductance in a zero net magnetic field at certain values of the parameters is presented. The quantization is due to the existence of a topological winding number that characterizes the quantum ... More
Incentive Schemes for Mobile Peer-to-Peer Systems and Free Riding Problem: A SurveyJun 23 2016Mobile peer-to-peer networks are quite prevalent and popular now days due to advent of business scenarios where all the services are going mobile like whether it's to find good restaurants, healthy diet books making friends, job-hunting, real state info ... More
User-level DSM System for Modern High-Performance Interconnection NetworksMar 22 2007In this paper, we introduce a new user-level DSM system which has the ability to directly interact with underlying interconnection networks. The DSM system provides the application programmer a flexible API to program parallel applications either using ... More
Invisibility System Using Image Processing and Optical Camouflage TechnologyFeb 08 2014Invisible persons are seen in fiction stories only, but in the real world it is proved that invisibility is possible. This paper describes the creation of invisibility with the help of technologies like Optical camouflage; Image based rendering and Retro ... More
Space like strong unique continuation for sublinear parabolic equationsDec 26 2018In this paper, we establish space like strong unique continuation property (sucp) for uniformly parabolic sublinear equations under appropriate structural assumptions. Our main result Theorem 1.1 constitutes the parabolic counterpart of the strong unique ... More
On the derived functors of the third symmetric-power functorNov 03 2009We compute the derived functors of the third symmetric-power functor and their cross-effects for certain values. These calculations match predictions by the first named author and largely prove them in general.
Global stability analysis of axisymmetric boundary layersAug 29 2016This paper presents the linear global stability analysis of the incompressible axisymmetric boundary layer on a circular cylinder. The base flow is parallel to the axis of the cylinder at inlet. The pressure gradient is zero in the streamwise direction. ... More
Global stability analysis of axisymmetric boundary layer over a circular coneAug 27 2016This paper presents the linear Global stability analysis of the incompressible axisymmetric boundary layer on a circular cone. The base flow is considered parallel to the axis of cone at the inlet. The angle of attack is zero and hence the base flow is ... More
Advection-Dominated Accretion: Underfed Black Holes and Neutron StarsNov 15 1994Jul 29 1995We describe new optically thin solutions for rotating accretion flows around black holes and neutron stars. These solutions are advection dominated, so that most of the viscously dissipated energy is advected radially with the flow. We model the accreting ... More
Advection-Dominated Accretion: A Self-Similar SolutionMar 23 1994We consider viscous rotating accretion flows in which most of the viscously dissipated energy is stored as entropy rather than being radiated. Such advection-dominated flows may occur when the optical depth is either very small or very large. We obtain ... More
Density jump as a function of magnetic field strength for parallel collisionless shocks in pair plasmasOct 16 2018Collisionless shocks follow the Rankine-Hugoniot jump conditions to a good approximation. However, for a shock propagating parallel to a magnetic field, magnetohydrodynamics states that the shock properties are independent of the field strength, whereas ... More
New Iterative Methods for Interpolation, Numerical Differentiation and Numerical IntegrationSep 09 2008Sep 10 2008Through introducing a new iterative formula for divided differnce using Neville's and Aitken's algorithms,we study new iterative methods for interpolation,numerical differentiation and numerical integration formulas with arbitrary order of accuracy for ... More
Electron Heating by the Ion Cyclotron Instability in Collisionless Accretion Flows. I. Compression-Driven Instabilities and the Electron Heating MechanismNov 20 2014In systems accreting well below the Eddington rate, the plasma in the innermost regions of the disk is collisionless and two-temperature, with the ions hotter than the electrons. Yet, whether a collisionless faster-than-Coulomb energy transfer mechanism ... More
X-ray Lines From Gamma-ray BurstsMay 28 2002X-ray lines have been recently detected in the afterglows of a few gamma-ray bursts. We derive constraints on the physical conditions in the line-emitting gas, using as an example the multiple K$_\alpha$ lines detected by Reeves et al. (2002) in GRB 011211. ... More
On Osculating InterpolationDec 30 2008May 05 2011The development of high-degree interpolation polynomials which use the values of the function and its subsequent derivatives is reformulated. Also, we present a variant of new formula in barycentric form.
Model Checking of Statechart Models: Survey and Research DirectionsJul 16 2004We survey existing approaches to the formal verification of statecharts using model checking. Although the semantics and subset of statecharts used in each approach varies considerably, along with the model checkers and their specification languages, ... More
A combinatorial characterization of finite groups of prime exponentMay 30 2018Mar 19 2019The power graph of a group $G$ is a simple and undirected graph with vertex set $G$ and two distinct vertices are adjacent if one is a power of the other. In this article, we characterize (non-cyclic) finite groups of prime exponent and finite elementary ... More
High mode magnetohydrodynamic waves propagation in a twisted rotating jet emerging from a filament eruptionMay 19 2018We study the conditions under which high mode magnetohydrodynamic (MHD) waves propagating on a rotating jet emerging from the filament eruption on 2013 April 10--11 can became unstable against the Kelvin--Helmholtz instability (KHI). The evolution of ... More
New Formulas and Methods for Interpolation, Numerical Differentiation and Numerical IntegrationSep 02 2008We present a new formula for divided difference and few new schemes of divided difference tables in this paper. Through this, we derive new interpolation, numerical differentiation and numerical integration formulas with arbitrary order of accuracy for ... More
Infrared Behaviour of Systems With Goldstone BosonsFeb 01 1995Dec 16 1997We develop various complementary concepts and techniques for handling quantum fluctuations of Goldstone bosons.We emphasise that one of the consequences of the masslessness of Goldstone bosons is that the longitudinal fluctuations also have a diverging ... More
Structural and vibrational properties of nitrogen-rich energetic material guanidinium 2-methyl-5-nitraminotetrazolateFeb 14 2014We present density functional theory calculations on the crystal structure, equation of state, vibrational properties and electronic structure of nitrogen-rich solid energetic material guanidinium 2-methyl-5-nitraminotetrazolate (G-MNAT). The ground state ... More
{\it Ab-initio} study of structural and vibrational properties of KN$_3$ under pressureNov 05 2013Structural stability and vibrational properties of KN$_3$ have been studied under pressure using the first principles calculations based on the density functional theory (DFT) as well as with semi empirical dispersion correction to the DFT to treat van ... More
A New Scheduling Algorithms For Real Time TasksDec 03 2009The main objective of this paper is to develop the two different ways in which round robin architecture is modified and made suitable to be implemented in real time and embedded systems. The scheduling algorithm plays a significant role in the design ... More
Improved Fair-Zone technique using Mobility Prediction in WSNMay 08 2012The self-organizational ability of ad-hoc Wireless Sensor Networks (WSNs) has led them to be the most popular choice in ubiquitous computing. Clustering sensor nodes organizing them hierarchically have proven to be an effective method to provide better ... More
Human Navigational Performance in a Complex Network with Progressive DisruptionsApr 18 2012The current paper is an investigation towards understanding the navigational performance of humans on a network when the "landmark" nodes are blocked. We observe that humans learn to cope up, despite the continued introduction of blockages in the network. ... More
On the general constraints in single qubit quantum process tomographyApr 26 2016We briefly review single-qubit quantum process tomography for trace-preserving and nontrace-preserving processes, and derive explicit forms of the general constraints for fitting experimental data. These new forms provide additional insight into the structure ... More
Density functional study of electronic structure, elastic and optical properties of MNH$_2$ (M=Li, Na, K, Rb)May 30 2014We report systematic first principles density functional study on the electronic structure, elastic and optical properties of nitrogen based solid hydrogen storage materials LiNH$_2$, NaNH$_2$, KNH$_2$, and RbNH$_2$. The ground state structural properties ... More
On the Estimation and Control of Human Body CompositionApr 04 2017Obesity is a chronic disease that can lead to an increased risk of other serious chronic diseases and even death. We present switching and time-delayed feedback-based model free control methods for the dynamic management of body mass and its major components. ... More
A feature extraction technique based on character geometry for character recognitionFeb 17 2012This paper describes a geometry based technique for feature extraction applicable to segmentation-based word recognition systems. The proposed system extracts the geometric features of the character contour. This features are based on the basic line types ... More
On single qubit quantum process tomography for trace-preserving and nontrace-preserving mapsFeb 03 2015We review single-qubit quantum process tomography for trace-preserving and nontrace-preserving processes, and derive explicit forms of the general constraints for fitting experimental data. These forms provide additional insight into the structure of ... More
Observational Evidence for Black HolesDec 23 2013Jul 20 2014Astronomers have discovered two populations of black holes: (i) stellar-mass black holes with masses in the range 5 to 30 solar masses, millions of which are present in each galaxy in the universe, and (ii) supermassive black holes with masses in the ... More
Inclination Effects and Beaming in Black Hole X-ray BinariesOct 22 2004Jan 11 2005We investigate the dependence of observational properties of black hole X-ray binaries on the inclination angle i of their orbits. We find the following: (1) Transient black hole binaries show no trend in their quiescent X-ray luminosities as a function ... More
Evidence for the Black Hole Event HorizonApr 26 2002Roughly a dozen X-ray binaries are presently known in which the compact accreting primary stars are too massive to be neutron stars. These primaries are identified as black holes, though there is as yet no definite proof that any of the candidate black ... More
Where are all the gravastars? Limits upon the gravastar model from accreting black holesJan 29 2007The gravastar model, which postulates a strongly correlated thin shell of anisotropic matter surrounding a region of anti-de Sitter space, has been proposed as an alternative to black holes. We discuss constraints that present-day observations of well-known ... More
Thermal Conduction in Clusters of GalaxiesOct 26 2001We estimate the thermal conductivity of a weakly collisional magnetized plasma with chaotic magnetic field fluctuations. When the fluctuation spectrum extends over two or more decades in wave-vector, we find that thermal conduction is very efficient; ... More
The Optics of Refractive SubstructureJun 20 2016Newly recognized effects of refractive scattering in the ionized interstellar medium have broad implications for very long baseline interferometry (VLBI) at extreme angular resolutions. Building upon work by Blandford & Narayan (1985), we present a simplified, ... More
Low frequency observations of transient quasi-periodic radio emission from the solar atmosphereNov 16 2016We report low frequency observations of the quasi-periodic, circularly polarized, harmonic type III radio bursts whose associated sunspot active regions were located close to the solar limb. The measured periodicity of the bursts at 80 MHz was $\approx$ ... More
Dirac or Inverse Seesaw Neutrino Masses from Gauged B - L SymmetryApr 01 2015The gauged $B - L$ symmetry is one of the simplest and well studied extension of standard model. In the conventional case, addition of three singlet right handed neutrinos each transforming as $-1$ under the $B - L$ symmetry renders it anomaly free. It ... More
On The Injection Spectrum of Ultrahigh Energy Cosmic Rays in the Top-Down ScenarioMar 31 2004May 13 2004We analyze the uncertainties involved in obtaining the injection spectra of UHECR particles in the top-down scenario of their origin. We show that the DGLAP $Q^2$ evolution of fragmentation functions (FF) to $Q=M_X$ (mass of the X particle) from their ... More
Proportionate growth in patterns formed in the rotor-router modelDec 24 2013We study the growing patterns in the rotor-router model formed by adding $N$ walkers at the center of a $L \times L$ two-dimensional square lattice, starting with a periodic background of arrows, and relaxing to a stable configuration. The pattern is ... More
Melting of a nonequilibrium vortex crystal in a fluid film with polymers : elastic versus fluid turbulenceFeb 25 2016Mar 18 2016We perform a direct numerical simulation (DNS) of the forced, incompressible two-dimensional Navier-Stokes equation coupled with the FENE-P equations for the polymer-conformation tensor. The forcing is such that, without polymers and at low Reynolds numbers ... More
Quantum Anomalous Hall State in Bilayer GrapheneSep 02 2010Sep 29 2010We present a symmetry-based analysis of competition between different gapped states that have been proposed in bilayer graphene (BLG), which are all degenerate on a mean field level. We classify the states in terms of a hidden SU(4) symmetry, and distinguish ... More
A LEO-Based Solar-Shade System to Mitigate Global WarmingApr 20 2015The development of a Low-Earth-Orbit (LEO) based solar-shade system, as part of a technically- and financially-viable multipurpose system to provide long-term solutions to global warming and the energy crisis is discussed. The proposed solar-shade and ... More
Semantic Interlinking of Resources in the Virtual Observatory EraMar 30 2011In the coming era of data-intensive science, it will be increasingly important to be able to seamlessly move between scientific results, the data analyzed in them, and the processes used to produce them. As observations, derived data products, publications, ... More
Finding Approximate Nash Equilibria of Bimatrix Games via Payoff QueriesOct 28 2013Feb 12 2014We study the deterministic and randomized query complexity of finding approximate equilibria in bimatrix games. We show that the deterministic query complexity of finding an $\epsilon$-Nash equilibrium when $\epsilon < \frac{1}{2}$ is $\Omega(k^2)$, even ... More
Statistics of the inverse-cascade regime in two-dimensional magnetohydrodynamic turbulenceMar 26 2014We present a detailed direct numerical simulation of statistically steady, homogeneous, isotropic, two-dimensional magnetohydrodynamic (2D MHD) turbulence. Our study concentrates on the inverse cascade of the magnetic vector potential. We examine the ... More
The moduli space of twisted canonical divisorsAug 31 2015Apr 03 2016The moduli space of canonical divisors (with prescribed zeros and poles) on nonsingular curves is not compact since the curve may degenerate. We define a proper moduli space of twisted canonical divisors in the moduli space of Deligne-Mumford stable pointed ... More
$η_c$ production and dimuon enhancement in heavy ion collisionsJan 14 2003Dilepton production in heavy ion collisions, in the Intermediate Mass Region (IMR) has consistently shown an excess over theoretical estimates. An attempt to understand this discrepancy between the observed dilepton pairs and the theoretical estimate ... More
A mean-field theory of nearly many-body localized metalsMay 05 2014Dec 09 2014We develop a mean-field theory of the metallic phase near the many-body localization (MBL) transition, using the observation that a system near the MBL transition should become an increasingly slow heat bath for its constituent parts. As a first step, ... More
Robust Online Speed Scaling With Deadline UncertaintyNov 14 2017A speed scaling problem is considered, where time is divided into slots, and jobs with payoff $v$ arrive at the beginning of the slot with associated deadlines $d$. Each job takes one slot to be processed, and multiple jobs can be processed by the server ... More
Conormal Varieties on the Cominuscule GrassmannianDec 19 2017Apr 17 2018Let $G$ be a simply connected, almost simple group over an algebraically closed field $\mathbf k$, and $P$ a maximal parabolic subgroup corresponding to omitting a cominuscule root. We construct a compactification $\phi:T^*G/P\rightarrow X(u)$, where ... More
Isotropic-nematic behaviour of hard rigid rods: a percolation theoretic approachOct 06 2016Needles at different orientations are placed in an i.i.d. manner at points of a Poisson point process on $\mathbb R^2$ of density $\lambda$. Needles at the same direction have the same length, while needles at different directions maybe of different lengths. ... More
Variations on a theorem of BeurlingMar 06 2012We consider functions satisfying the subcritical Beurling's condition, viz., $$\int_{\R^n}\int_{\R^n} |f(x)| |\hat{f}(y)| e^{a |x \cdot y|} \, dx \, dy < \infty$$ for some $ 0 < a < 1.$ We show that such functions are entire vectors for the Schr\"{o}dinger ... More
A Fock space approach to Severi degreesOct 30 2012The classical Severi degree counts the number of algebraic curves of fixed genus and class passing through points in a surface. We express the Severi degrees of CP1 x CP1 as matrix elements of the exponential of a single operator M on Fock space. The ... More