Results for "Shourya Khanna"

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Asteroseismology of 16000 Kepler red giants: Global oscillation parameters, Masses, and radiiFeb 13 2018The Kepler mission has provided exquisite data to perform an ensemble asteroseismic analysis on evolved stars. In this work we systematically characterize solar-like oscillations and granulation for 16,094 oscillating red giants, using end-of-mission ... More
Probing the photoionised outflow in the NLS1 Ark 564: An XMM-Newton viewNov 10 2015We present a detailed analysis of xmm X-ray observations of the Narrow line Seyfert-1 (NLS1) galaxy Ark 564 taken between 2000 and 2011. High-resolution X-ray spectroscopy is carried out on the resultant high signal-to-noise stacked spectrum. We find ... More
The TESS-HERMES survey Data Release 1: high-resolution spectroscopy of the TESS southern continuous viewing zoneJul 18 2017Sep 30 2017The Transiting Exoplanet Survey Satellite (TESS) will provide high precision time-series photometry for millions of stars with at least a half-hour cadence. Of particular interest are the circular regions of 12-degree radius centered around the ecliptic ... More
Battery and Dynamo theory in the Kerr metricApr 16 1999The generation and evolution of magnetic fields in the plasma accreting into a rotating black hole is studied in the 3+1 split of the Kerr metric. Attention is focused on effects of the gravitomagnetic potential. The gravitomagnetic force appears as battery ... More
Generation of Magnetic Fields by a Gravitomagnetic Plasma BatteryMar 20 1998The generation of magnetic fields by a battery, operating in an ion-electron plasma around a Kerr black hole, is studied in the 3+1 split of the Kerr metric. It is found that the gravitomagnetic contributions to the electron partial pressure are able ... More
An Iterative Transfer Learning Based Ensemble Technique for Automatic Short Answer GradingSep 16 2016Sep 19 2016Automatic short answer grading (ASAG) techniques are designed to automatically assess short answers to questions in natural language, having a length of a few words to a few sentences. Supervised ASAG techniques have been demonstrated to be effective ... More
The CBE Hardware Accelerator for Numerical Relativity: A Simple ApproachNov 08 2009Hardware accelerators (such as the Cell Broadband Engine) have recently received a significant amount of attention from the computational science community because they can provide significant gains in the overall performance of many numerical simulations ... More
Evolution of Kerr-Schild type initial data for binary black holes using the horizon penetrating Teukolsky equationJan 16 2002Jan 21 2002We use the Kerr-Schild type Teukolsky equation (horizon penetrating) to evolve binary black hole initial data as proposed by Bishop {\em et al.} in the close limit. Our results are in agreement with those recently obtained by Sarbach {\em et al.} from ... More
Collision of spinning black holes in the close limitJan 03 2001In this paper we consider the collision of spinning holes using first order perturbation theory of black holes (Teukolsky formalism). With these results (along with ones, we published in the past) one can predict the properties of the gravitational waves ... More
Generation and evolution of magnetic fields in the gravitomagnetic field of a Kerr Black HoleMar 05 1999I study the generation and evolution of magnetic fields in the plasma surrounding a rotating black hole. Attention is focused on effects of the gravitomagnetic potential. The gravitomagnetic force appears as battery term in the generalized Ohm's law. ... More
Teukolsky evolution of particle orbits around Kerr black holes in the time domain: elliptic and inclined orbitsSep 22 2003We extend the treatment of the problem of the gravitational waves produced by a particle of negligible mass orbiting a Kerr black hole using black hole perturbation theory in the time domain, to elliptic and inclined orbits. We model the particle by smearing ... More
Collision of spinning black holes in the close limit: The parallel spin caseJun 03 2002Aug 23 2002In this paper we consider the collision of black holes with parallel spins using first order perturbation theory of rotating black holes (Teukolsky formalism). The black holes are assumed to be close to each other, initially non boosted and spinning slowly. ... More
On the magnetohydrodynamic description of a two-component plasma in the Kerr metricMar 09 1998The magnetohydrodynamic equations describing an inviscid, fully ionized plasma in the vicinity of a rotating black hole are derived from a two-component plasma theory within the framework of the 3+1 split of the Kerr metric. Of central interest is the ... More
The K2-HERMES Survey. I. Planet Candidate Properties from K2 Campaigns 1-3Dec 19 2017Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions and formation mechanisms. To know the planet, we must know the host star in as much detail as possible. We present first results from the ... More
An Iterative Transfer Learning Based Ensemble Technique for Automatic Short Answer GradingSep 16 2016Nov 21 2016Automatic short answer grading (ASAG) techniques are designed to automatically assess short answers to questions in natural language, having a length of a few words to a few sentences. Supervised ASAG techniques have been demonstrated to be effective ... More
Holistic Influence Maximization: Combining Scalability and Efficiency with Opinion-Aware ModelsFeb 09 2016The steady growth of graph data from social networks has resulted in wide-spread research in finding solutions to the influence maximization problem. In this paper, we propose a holistic solution to the influence maximization (IM) problem. (1) We introduce ... More
Signature of strong atom-cavity interaction on critical couplingJan 19 2010We study a critically coupled cavity doped with resonant atoms with metamaterial slabs as mirrors. We show how resonant atom-cavity interaction can lead to a splitting of the critical coupling dip. The results are explained in terms of the frequency and ... More
Sensitivity and Computational Complexity in Financial NetworksMar 26 2015Oct 25 2016Modern financial networks exhibit a high degree of interconnectedness and determining the causes of instability and contagion in financial networks is necessary to inform policy and avoid future financial collapse. In the American Economic Review, Elliott, ... More
Absence of pre-classical solutions in Bianchi I loop quantum cosmologyJan 06 2005Feb 16 2005Loop quantum cosmology, the symmetry reduction of quantum geometry for the study of various cosmological situations, leads to a difference equation for its quantum evolution equation. To ensure that solutions of this equation act in the expected classical ... More
A self-regulated model of galactic spiral structure formationMay 22 2001Feb 19 2002The presence of spiral structure in isolated galaxies is a problem that has only been partially explained by theoretical models. Because the rate and pattern of star formation in the disk must depend only on mechanisms internal to the disk, we may think ... More
Black holes in anti-de Sitter: quasinormal modes, tails and tales of flat spacetimeJan 05 2015Jan 08 2015Black holes in asymptotically anti-de Sitter (AdS) spacetimes have been the subject of intense scrutiny, including detailed frequency-domain analysis and full nonlinear evolutions. Remarkably, studies of linearized perturbations in the time-domain are ... More
Null infinity waveforms from extreme-mass-ratio inspirals in Kerr spacetimeAug 08 2011Dec 12 2011We describe the hyperboloidal compactification for Teukolsky equations in Kerr spacetime. We include null infinity on the numerical grid by attaching a hyperboloidal layer to a compact domain surrounding the rotating black hole and the orbit of an inspiralling ... More
An exploration of CUDA and CBEA for a gravitational wave data-analysis application (Einstein@Home)Apr 12 2009Jun 29 2009We present a detailed approach for making use of two new computer hardware architectures -- CBEA and CUDA -- for accelerating a scientific data-analysis application (Einstein@Home). Our results suggest that both the architectures suit the application ... More
Sensitivity and Computational Complexity in Financial NetworksMar 26 2015Modern financial networks exhibit a high degree of interconnectedness and determining the causes of instability and contagion in financial networks is necessary to inform policy and avoid future financial collapse. In the American Economic Review, Elliott, ... More
Improved Hardness of Approximation for Stackelberg Shortest-Path PricingOct 01 2009We consider the Stackelberg shortest-path pricing problem, which is defined as follows. Given a graph G with fixed-cost and pricable edges and two distinct vertices s and t, we may assign prices to the pricable edges. Based on the predefined fixed costs ... More
Wave functions for the Schwarschild black hole interiorFeb 07 2006Apr 08 2006Using the Hamiltonian constraint derived by Ashtekar and Bojowald, we look for pre-classical wave functions in the Schwarzschild interior. In particular, when solving this difference equation by separation of variables, an inequality is obtained relating ... More
Brief note on high-multipole Kerr tailsDec 18 2013Jan 19 2015In this note we reconsider the late-time, power-law decay rate of scalar fields in a Kerr space-time background. We implement a number of mathematical and computational enhancements to our time-domain, (2+1)D Teukolsky evolution code and are able to obtain ... More
An exploration of CUDA and CBEA for a gravitational wave source-modelling applicationSep 22 2009In this paper, we accelerate a gravitational physics numerical modelling application using hardware accelerators -- Cell processor and Tesla CUDA GPU. We describe these new technologies and our approach in detail, and then present our final performance ... More
Numerical solutions to lattice-refined models in loop quantum cosmologyNov 13 2007In this article, we develop an intuitive and efficient, numerical technique to solve the quantum evolution equation of generic lattice-refined models in loop quantum cosmology. As an application of this method, we extensively study the solutions of the ... More
Scientific Computing Using Consumer Video-Gaming Hardware DevicesJul 19 2016Commodity video-gaming hardware (consoles, graphics cards, tablets, etc.) performance has been advancing at a rapid pace owing to strong consumer demand and stiff market competition. Gaming hardware devices are currently amongst the most powerful and ... More
High-Precision Numerical Simulations of Rotating Black Holes Accelerated by CUDAJun 03 2010Hardware accelerators (such as Nvidia's CUDA GPUs) have tremendous promise for computational science, because they can deliver large gains in performance at relatively low cost. In this work, we focus on the use of Nvidia's Tesla GPU for high-precision ... More
Delays and the Capacity of Continuous-time ChannelsMay 17 2011Any physical channel of communication offers two potential reasons why its capacity (the number of bits it can transmit in a unit of time) might be unbounded: (1) Infinitely many choices of signal strength at any given instant of time, and (2) Infinitely ... More
An $O(k^{3} log n)$-Approximation Algorithm for Vertex-Connectivity Survivable Network DesignDec 23 2008In the Survivable Network Design problem (SNDP), we are given an undirected graph $G(V,E)$ with costs on edges, along with a connectivity requirement $r(u,v)$ for each pair $u,v$ of vertices. The goal is to find a minimum-cost subset $E^*$ of edges, that ... More
Numerical modeling of gravitational wave sources accelerated by OpenCLJan 20 2010Oct 04 2011In this work, we make use of the OpenCL framework to accelerate an EMRI modeling application using the hardware accelerators -- Cell BE and Tesla CUDA GPU. We describe these compute technologies and our parallelization approach in detail, present our ... More
Approximate pre-classical solutions in loop quantum cosmologySep 20 2005In this paper we introduce a numerical approximation technique to obtain pre-classical solutions to models of loop quantum gravity. In particular, we apply the technique to vacuum Bianchi I cosmological models and recover known solutions. We also present ... More
Separable sequences in Bianchi I loop quantum cosmologyJun 05 2005Oct 18 2005In this paper, we discuss the properties of one-parameter sequences that arise when solving the Hamiltonian constraint in Bianchi I loop quantum cosmology using a separation of variables method. In particular, we focus on finding an expression for the ... More
Self-regulated models of spiral structure formationSep 10 1999Jan 22 2002Withdrawn; paper superceded by astro-ph/0105392
Self-force gravitational waveforms for extreme and intermediate mass ratio inspirals. II: Importance of the second-order dissipative effectApr 19 2013Jun 19 2013We consider the importance of the second-order dissipative self force for gravitational wave dephasing for an extreme or intermediate mass ratio system moving along a quasi-circular Schwarzschild orbit. For the first-order self force we use the fully ... More
Self-force gravitational waveforms for extreme and intermediate mass ratio inspirals. III: Spin-orbit coupling revisitedMar 17 2015Apr 30 2015The first- and second-order dissipative self force and the first order conservative self force are applied together with spin-orbit coupling to the quasi-circular motion of a test mass in the spacetime of a Schwarzschild black hole, for extreme or intermediate ... More
Accurate time-domain gravitational waveforms for extreme-mass-ratio binariesAug 31 2006Feb 07 2007The accuracy of time-domain solutions of the inhomogeneous Teukolsky equation is improved significantly. Comparing energy fluxes in gravitational waves with highly accurate frequency-domain results for circular equatorial orbits in Schwarzschild and Kerr, ... More
$Λ^+_c$, $Σ_c$, $Ξ_c$ and $Λ_b$ hypernuclei in the quark-meson coupling modelMar 29 2003Sep 06 2004Charmed (and bottom) hypernuclei are studied in the quark-meson coupling (QMC) model. This completes systematic studies of charmed ($\Lambda_c^+, \Sigma_c, \Xi_c$), and $\Lambda_b$ hypernuclei in the QMC model. Effects of the Pauli blocking due to the ... More
Lepton U_l(1) symmetry and interaction of neutrinos with deuterons at high energiesJul 17 2000The following items are discussed: 1. The lepton U_l(1) symmetry and its relation to the presence of the neutrino mass term in the Hamiltonian. 2. The possibility of the measurement of the neutrino-deuteron reactions with high energy neutrinos at SNO ... More
Different Operating Systems Compatible for Image Prepress Process in Color Management: Analysis and Performance TestingNov 07 2012Image computing has become a real catchphrase over the past few years and the interpretations of the meaning of the term vary greatly. The Imagecomputing market is currently rapidly evolving with high growth prospects and almost daily announcements of ... More
Reproduction of Images by Gamut Mapping and Creation of New Test Charts in Prepress ProcessSep 26 2012With the advent of digital images the problem of keeping picture visualization uniformity arises because each printing or scanning device has its own color chart. So, universal color profiles are made by ICC to bring uniformity in various types of devices. ... More
An Implementation of Computer Graphics as Prepress Image Enhancement ProcessSep 23 2012The production of a printed product involves three stages: prepress, the printing process (press) itself, and finishing (post press). There are various types of equipments (printers, scanners) and various qualities image are present in the market. These ... More
Screening length, dispersion relations and quark potential in thermo field dynamicsNov 14 2000The screening length in a quark-gluon plasma, the dispersion relations of thermal gluon self-energy and the quark potential at high temperature are studied within thermo field dynamics framework. By calculation of the real and imaginary parts, of the ... More
Some Comments of Vlasov-Liouville Equation and its Relation with Gravitational FieldJun 16 2000We discuss here the possibility to write the Liouville-Vlasov equation for the Wigner-function of a spinor field coupled to a gauge field with field strength tensor $F^{\mu\nu}$ in a curved space-time versus a local Lorentz manifold (introduction of local ... More
$Λ^+_c$- and $Λ_b$-hypernucleiJul 26 2002Dec 09 2002$\Lambda^+_c$- and $\Lambda_b$-hypernuclei are studied in the quark-meson coupling (QMC) model. Comparisons are made with the results for $\Lambda$-hypernuclei studied in the same model previously. Although the scalar and vector potentials felt by the ... More
Late-time Kerr tails: generic and non-generic initial data sets, "up" modes, and superpositionJan 04 2010Oct 25 2010Three interrelated questions concerning Kerr spacetime late-time scalar-field tails are considered numerically, specifically the evolutions of generic and non-generic initial data sets, the excitation of "up" modes, and the resolution of an apparent paradox ... More
Radiative falloff in the background of rotating black holeSep 27 2002Mar 06 2003We study numerically the late-time tails of linearized fields with any spin $s$ in the background of a spinning black hole. Our code is based on the ingoing Kerr coordinates, which allow us to penetrate through the event horizon. The late time tails are ... More
On radiative muon capture in hydrogenFeb 02 2001Nov 22 2001We analyze photon spectra in the radiative muon capture in hydrogen using amplitudes derived from chiral Lagrangians. The model can describe the high energy part of the photon spectra, measured recently at TRIUMF, reasonably well.
von Neumann Lattices in Finite Dimensions Hilbert SpacesMay 07 2008The prime number decomposition of a finite dimensional Hilbert space reflects itself in the representations that the space accommodates. The representations appear in conjugate pairs for factorization to two relative prime factors which can be viewed ... More
Creation of Digital Test Form for Prepress DepartmentSep 23 2012The main problem in colour management in prepress department is lack of availability of literature on colour management and knowledge gap between prepress department and press department. So a digital test from has been created by Adobe Photoshop to analyse ... More
Black Hole Ringing, Quasinormal Modes, and Light RingsSep 01 2016Sep 11 2016Modelling of gravitational waves from binary black hole inspiral has played an important role in the recent observations of such signals. The late-stage ringdown phase of the gravitational waveform is often associated with the null particle orbit ("light ... More
Universality of massive scalar field late-time tails in black-hole spacetimesMar 03 2004Aug 26 2004The late-time tails of a massive scalar field in the spacetime of black holes are studied numerically. Previous analytical results for a Schwarzschild black hole are confirmed: The late-time behavior of the field as recorded by a static observer is given ... More
Massive scalar field instability in Kerr spacetimeDec 05 2004We study the Klein-Gordon equation for a massive scalar field in Kerr spacetime in the time-domain. We demonstrate that under conditions of super-radiance, the scalar field becomes unstable and its amplitude grows without bound. We also estimate the growth ... More
Decentralized Joint-Sparse Signal Recovery: A Sparse Bayesian Learning ApproachJul 09 2015Dec 18 2015This work proposes a decentralized, iterative, Bayesian algorithm called CB-DSBL for in-network estimation of multiple jointly sparse vectors by a network of nodes, using noisy and underdetermined linear measurements. The proposed algorithm exploits the ... More
Some Comments on Wheeler De Witt Equation for Gravitational Collapse and the Problem of TimeJun 19 2000We write the Hamiltonian for a gravitational spherically symmetric scalar field collapse with massive scalar field source, and we discuss the application of Wheeler De Witt equation as well as the appearence of time in this context. Using an Ansatz for ... More
Quantum Gravity in D=5 DimensionsJun 16 2000Jun 22 2000We propose a topological Chern-Simons term in D=5 dimensions coupled to Einstein Hilbert theory. Hartree approximation for topological Lagrangian and the Chern-Simons term in D=3 is considered. An effective model of Quantum Gravity in D=5 dimensions is ... More
Weak axial exchange currents for the Bethe-Salpeter equationNov 05 1999Nov 06 1999We construct weak axial one-boson exchange currents for the Bethe-Salpeter equation, starting from chiral Lagrangians of the N-\Delta(1236)-pi-rho-a_1-omega system. The currents fulfil the Ward-Takahashi identities and the matrix element of the full current ... More
Late-time Kerr tails revisitedNov 06 2007Mar 19 2008The decay rate of late time tails in the Kerr spacetime have been the cause of numerous conflicting results, both analytical and numerical. In particular, there is much disagreement on whether the decay rate of an initially pure multipole moment ${\ell}$ ... More
Encryption via Entangled states belonging to Mutually Unbiased BasesSep 11 2008We consider particular entanglement of two particles whose state vectors are in bases that are mutually unbiased (MUB), i.e. "that exhibit maximum degree of incompatibility" (J.Schwinger,Nat. Ac. Sci. (USA), 1960)). We use this link between entanglement ... More
Developing ICC Profile Using Gray Level Control In Offset Printing ProcessOct 21 2012In prepress department RGB image has to be converted to CMYK image. To control that amount of black, cyan, magenta and yellow has to be controlled by using color separation method. Graycolor separation method is selected to control the amounts of these ... More
New Solutions for Evolution of the Scale Factor with a Variable Cosmological TermJun 22 2000The cosmological term is assumed to be a function of time such as $\Lambda =Ba^{-2}$ where a(t) means the scale factor of standard cosmology. Analytical solutions for radiation dominated epoch and open universe are found. For closed universe, k=+1, and ... More
Coherent perfect absorption mediated anomalous reflection and refractionJul 23 2012We demonstrate bending of light on the same side of the normal in a free standing corrugated metal film under bi-directional illumination. Coherent perfect absorption (CPA) is exploited to suppress the specular zeroth order leading to effective back-bending ... More
Controllable coherent perfect absorption in a composite filmNov 18 2011We exploit the versatility provided by metal--dielectric composites to demonstrate controllable coherent perfect absorption (CPA) in a slab of heterogeneous medium. The slab is illuminated by coherent light from both sides, at the same angle of incidence ... More
Properties of charmed and bottom hadrons in nuclear matter: A plausible studyJul 12 2002Dec 03 2002Changes in properties of heavy hadrons with a charm or a bottom quark are studied in nuclear matter. Effective masses (scalar potentials) for the hadrons are calculated using quark-meson coupling model. Our results also suggest that the heavy baryons ... More
Masses of Heavy HadronsMay 09 2000An estimate has been made of the masses of heavy hadrons in nonrelativistic quark model, which includes spin and flavor-dependent hyperfine splitting for two quarks. The effect of variation of the wavefunction value at origin and the strong coupling constant, ... More
Gravitational waves from a plunge into a nearly extremal Kerr black holeAug 07 2016We study numerically in the time domain the linearized gravitational waves emitted from a plunge into a nearly extremal Kerr black hole by solving the inhomogeneous Teukolsky equation. We consider spinning black holes for which the specific spin angular ... More
Mode coupling mechanism for late-time Kerr tailsDec 18 2013We consider the decay rate for scalar fields in Kerr spacetime. We consider pure initial (azimuthal) multipoles $\ell'$ with respect to the class which includes Boyer-Lindquist coordinates, and focus attention on the decay rate of the multipole $\ell$. ... More
Properties of charmed and bottom hadrons in nuclear medium: Results for $Λ_c^+$ and $Λ_b$ hypernucleiDec 26 2002This reports our recent studies on changes in properties of heavy hadrons containing at least a charm or a bottom quark in nuclear matter, and that the results for the $\Lambda^+_c$ and $\Lambda_b$ hypernuclei are studied quantitatively. Comparisons are ... More
Finite temperature amplitudes and reaction rates in Thermofield dynamicsNov 09 2000Sep 28 2001We propose a method for calculating the reaction rates and transition amplitudes of generic process taking place in a many body system in equilibrium. The relationship of the scattering and decay amplitudes as calculated in Thermo Field Dynamics the conventional ... More
Image Classification and Optimized Image ReproductionSep 23 2012By taking into account the properties and limitations of the human visual system, images can be more efficiently compressed, colors more accurately reproduced, prints better rendered. To show all these advantages in this paper new adapted color charts ... More
Arrival Times of Gravitational Radiation Peaks for Binary InspiralJul 14 2016Sep 27 2016Modeling of gravitational waves (GWs) from binary black hole inspiral brings together early post-Newtonian waveforms and late quasinormal ringing waveforms. Attempts to bridge the two limits without recourse to numerical relativity involve predicting ... More
Black Hole Entropy in 1+1 Dimensions from a Quasi-Chern Simons term in a Gravitational BackgroundJun 16 2000We introduce a 'quasi-topological` term [1] in D=1+1 dimensions and the entropy for black holes is calculated [2]. The source of entropy in this case is justified by a non-null stress-energy tensor.
Black Hole entropy in D=2+1 dimensions from extended Chern-Simons term in a gravitational backgroundJun 16 2000We study the contribution to entropy of Black Holes in D=2+1 dimensions from an extension of the Chern Simons theory including higher derivative in a curved space-time.
Behaviour of the $ΛN$ and $ΛNN$ potential strengths in the $_Λ^5$He hypernucleusDec 02 2006Variational study of $_\Lambda ^5$He hypernucleus is presented using a realistic Hamiltonian and a fully correlated wave function including $\Lambda N$ space-exchange correlation. Behaviour of the $\Lambda$-separation energy ($B_\Lambda$) with two- and ... More
Perfect Matchings via Uniform Sampling in Regular Bipartite GraphsNov 15 2008In this paper we further investigate the well-studied problem of finding a perfect matching in a regular bipartite graph. The first non-trivial algorithm, with running time $O(mn)$, dates back to K\"{o}nig's work in 1916 (here $m=nd$ is the number of ... More
Chiral Lagrangians and the transition amplitude for radiative muon captureNov 20 1998The transition operator for the radiative capture of mesons mu minus by protons is constructed starting from a chiral Lagrangian of the N-pi-rho-a_1-omega system obtained within the approach of hidden local symmetries. The transition operator is gauge ... More
On the muon capture in 28^Si and extraction of g_PMay 23 2001Comparison of the new data for the negative muon capture in 28^Si with the recent shell model calculations using a full 1s-0d model space and the USD empirical effective interaction and the one-nucleon weak current provides the induced pseudoscalar g_P ... More
Generating function techniques for loop quantum cosmologyMay 26 2004Aug 25 2004Loop quantum cosmology leads to a difference equation for the wave function of a universe, which in general has solutions changing rapidly even when the volume changes only slightly. For a semiclassical regime such small-scale oscillations must be suppressed, ... More
Cabibbo favored hadronic decays of charmed baryons in flavor SU(3)Jun 22 1995The two body Cabibbo favored hadronic decays of charmed baryons $\Lambda^{+}_{c}$, $\Xi^{+}_{c}$ and $\Xi_{c}^{0}$ into an octet or decuplet baryon and a pseudoscalar meson are examined in the SU(3) symmetry scheme. The numerical estimates for decay widths ... More
Graph Sparsification via Refinement SamplingApr 27 2010A graph G'(V,E') is an \eps-sparsification of G for some \eps>0, if every (weighted) cut in G' is within (1\pm \eps) of the corresponding cut in G. A celebrated result of Benczur and Karger shows that for every undirected graph G, an \eps-sparsification ... More
Electromagnetic isoscalar rho-pi-gamma exchange current and the anomalous actionOct 24 2000Using modern data, we first refit constants needed to complete an anomalous pi-rho-omega-a_1 Lagrangian obtained within the approach of hidden local symmetries. Then we derive from this Lagrangian electromagnetic isoscalar rho-pi-gamma and rho-a_1-gamma ... More
Quantized gravitoelectromagnetism theory at finite temperatureMay 23 2016The Gravitoelectromagnetism (GEM) theory is considered in a lagrangian formulation using the Weyl tensor components. A perturbative approach to calculate processes at zero temperature has been used. Here the GEM at finite temperature is analyzed using ... More
On $(1,ε)$-Restricted Assignment Makespan MinimizationOct 28 2014Makespan minimization on unrelated machines is a classic problem in approximation algorithms. No polynomial time $(2-\delta)$-approximation algorithm is known for the problem for constant $\delta> 0$. This is true even for certain special cases, most ... More
A multi-domain hybrid method for head-on collision of black holes in particle limitMar 08 2011May 10 2011A hybrid method is developed based on the spectral and finite-difference methods for solving the inhomogeneous Zerilli equation in time-domain. The developed hybrid method decomposes the domain into the spectral and finite-difference domains. The singular ... More
Transport and STM studies of hyperbolic surface states of topological insulatorsMar 15 2013Motivated by the transmission of topological surface states through atomic scale steps, we study the transport of gapless Dirac fermions on hyperbolic surfaces. We confirm that, independent of the curvature of the hyperbolae and the sharpness of the corners, ... More
Tight Bounds for Single-Pass Streaming Complexity of the Set Cover ProblemMar 17 2016We resolve the space complexity of single-pass streaming algorithms for approximating the classic set cover problem. For finding an $\alpha$-approximate set cover (for any $\alpha= o(\sqrt{n})$) using a single-pass streaming algorithm, we show that $\Theta(mn/\alpha)$ ... More
Lattice refining loop quantum cosmology, anisotropic models and stabilityApr 09 2007A general class of loop quantizations for anisotropic models is introduced and discussed, which enhances loop quantum cosmology by relevant features seen in inhomogeneous situations. The main new effect is an underlying lattice which is being refined ... More
Self Adjoint Extensions of Phase and Time OperatorsSep 23 2003It is shown that any real and even function of the phase (time) operator has a self-adjoint extension and its relation to the general phase operator problem is analyzed.
Black hole binary inspiral: Analysis of the plungeAug 19 2015Feb 05 2016Binary black hole coalescence has its peak of gravitational wave generation during the "plunge," the transition from quasicircular early motion to late quasinormal ringing. Although advances in numerical relativity have provided plunge waveforms, there ... More
Dynamic and Non-Uniform Pricing Strategies for Revenue MaximizationMay 19 2009We consider the Item Pricing problem for revenue maximization in the limited supply setting, where a single seller with $n$ items caters to $m$ buyers with unknown subadditive valuation functions who arrive in a sequence. The seller sets the prices on ... More
Perturbative evolution of particle orbits around Kerr black holes: time domain calculationMar 12 2003Mar 13 2003Treating the Teukolsky perturbation equation numerically as a 2+1 PDE and smearing the singularities in the particle source term by the use of narrow Gaussian distributions, we have been able to reproduce earlier results for equatorial circular orbits ... More
The Spin-Dependent Structure Functions of Nucleons and NucleiSep 13 1996We discuss connection between spin-dependent SFs of nucleons and nuclei in the deep inelastic lepton scattering. The case of the deuteron is studied in detail in the Bethe-Salpeter formalism.
The axial anomaly and the conversion of gluons into photonsMay 06 1996The axial anomaly in the divergence of the singlet axial current in QCD $+$ QED leads to low-energy theorems for the matrix element of this operator equation over vacuum and two--photon states and for the matrix element over vacuum and two--gluon states. ... More
Strong BBP couplings for the charmed baryonsJan 26 1995According to the Coleman-Glashow null theorem if all the symmetry breaking effects belong to the same regular representation (octet in the case of SU(3) and {\bf 15} in the case of SU(4)) and are generated in a tadpole type mechanism, the strangeness ... More
Testing the Cosmic Censorship Conjecture with point particles: the effect of radiation reaction and the self-forceJun 09 2011Oct 24 2011A classical thought-experiment to destroy black holes was envisaged by Wald in 1974: it consists of throwing particles with large angular momentum into an extremal black hole, checking whether their capture can over-spin the black hole past the extremal ... More
Test bodies and naked singularities: is the self-force the cosmic censor?Aug 30 2010Dec 17 2010Jacobson and Sotiriou showed that rotating black holes could be spun-up past the extremal limit by the capture of non-spinning test bodies, if one neglects radiative and self-force effects. This would represent a violation of the Cosmic Censorship Conjecture ... More
Mechanism Design and Risk AversionJul 24 2011Jun 27 2012We develop efficient algorithms to construct utility maximizing mechanisms in the presence of risk averse players (buyers and sellers) in Bayesian settings. We model risk aversion by a concave utility function, and players play strategically to maximize ... More