Results for "Sridhar Ravi"

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The viscosity radius in dilute polymer solutions: Universal behaviour from DNA rheology and Brownian dynamics simulationsMay 16 2014Oct 14 2014The swelling of the viscosity radius, $\alpha_\eta$, and the universal viscosity ratio, $U_{\eta R}$, have been determined experimentally for linear DNA molecules in dilute solutions with excess salt, and numerically by Brownian dynamics simulations, ... More
Significance of parallel computing on the performance of Digital Image Correlation algorithms in MATLABMay 15 2019Digital Image Correlation (DIC) is a powerful tool used to evaluate displacements and deformations in a non-intrusive manner. By comparing two images, one of the undeformed reference state of a specimen and another of the deformed target state, the relative ... More
Design of a magnetically actuated flapping wing contrivanceMar 18 2019Unmanned micro aerial vehicle research is an active area of development due to the vast potential applications. Prior work towards realizing flapping flight has achieved some success however they have relied heavily upon the use of rotary electric motors. ... More
Representation Policy IterationJul 04 2012This paper addresses a fundamental issue central to approximation methods for solving large Markov decision processes (MDPs): how to automatically learn the underlying representation for value function approximation? A novel theoretically rigorous framework ... More
Enhanced Secure Algorithm for Message CommunionOct 08 2011This paper puts forward a safe mechanism of data transmission to tackle the security problem of information which is transmitted in Internet. The encryption standards such as DES (Data Encryption Standard), AES (Advanced Encryption Standard) and EES (Escrowed ... More
Sparse Q-learning with Mirror DescentOct 16 2012This paper explores a new framework for reinforcement learning based on online convex optimization, in particular mirror descent and related algorithms. Mirror descent can be viewed as an enhanced gradient method, particularly suited to minimization of ... More
Trust Based Scheme for QoS Assurance in Mobile Ad-Hoc NetworksFeb 08 2012A mobile ad-hoc network (MANET) is a peer-to-peer wireless network where nodes can communicate with each other without the use of infrastructure such as access points or base stations. These networks are self-configuring, capable of self-directed operation ... More
Decision-Theoretic Planning with Concurrent Temporally Extended ActionsJan 10 2013We investigate a model for planning under uncertainty with temporallyextended actions, where multiple actions can be taken concurrently at each decision epoch. Our model is based on the options framework, and combines it with factored state space models,where ... More
Colour-octet Contributions to J/psi Hadroproduction at Fixed Target EnergiesJan 28 1996Jan 31 1996We investigate the integrated cross section for forward $\jpsi$ production in proton-proton and pion-proton collisions at centre of mass energies upto 60 GeV. We find that colour-octet contributions to the cross section are crucially important, and their ... More
A Predictive System for detection of Bankruptcy using Machine Learning techniquesFeb 12 2015Bankruptcy is a legal procedure that claims a person or organization as a debtor. It is essential to ascertain the risk of bankruptcy at initial stages to prevent financial losses. In this perspective, different soft computing techniques can be employed ... More
Probing Aromaticity of Borozene Through Optical and Dielectric Response: A Theoretical StudyDec 21 2009In this work, we report electronic structure calculations aimed at computing the linear optical absorption spectrum, and static dipole polarizablity of a newly proposed boron-based planar aromatic compound borozene (B_12H_6$. For the purpose, we use the ... More
Optimization of fuzzy analogy in software cost estimation using linguistic variablesSep 12 2012One of the most important objectives of software engineering community has been the increase of useful models that beneficially explain the development of life cycle and precisely calculate the effort of software cost estimation. In analogy concept, there ... More
Nonperturbative quasilinear approach to the shear dynamo problemJun 17 2009Jan 01 2010We study large-scale dynamo action due to turbulence in the presence of a linear shear flow. Our treatment is quasilinear and equivalent to the standard `first order smoothing approximation'. However it is non perturbative in the shear strength. We first ... More
Stellar orbits in triaxial clusters around black holes in galactic nucleiJul 24 2000We investigate the orbital structure of a model triaxial star cluster, centered around a supermassive black hole (BH), appropriate to galactic nuclei. Sridhar and Touma (1999) proved that the presence of the BH enforces some regularity in the dynamics ... More
Three dimensional, axisymmetric cusps without chaosApr 02 1997We construct three dimensional axisymmetric, cuspy density distributions, whose potentials are of St\"ackel form in parabolic coordinates. As in Sridhar and Touma (1997), a black hole of arbitrary mass may be added at the centre, without destroying the ... More
Response to sub-threshold stimulus is enhanced by spatially heterogeneous activityMay 27 2010Sub-threshold stimuli cannot initiate excitations in active media, but surprisingly as we show in this paper, they can alter the time-evolution of spatially heterogeneous activity by modifying the recovery dynamics. This results in significant reduction ... More
NeuroSVM: A Graphical User Interface for Identification of Liver PatientsFeb 19 2015Diagnosis of liver infection at preliminary stage is important for better treatment. In todays scenario devices like sensors are used for detection of infections. Accurate classification techniques are required for automatic identification of disease ... More
On the Nature of Optical Excitations in Hydrogenated Aluminium Cluster Al4H6: A Theoretical StudyJan 05 2010Jan 10 2010In this paper, we present a theoretical investigation of photoabsorption spectrum of the newly synthesized hydrogenated cluster of aluminium, Al4H6. The calculations are performed within the wave-function-based semi-empirical method employing the complete ... More
Generation of multipartite spin entanglement from multimode squeezed statesOct 18 2013We investigate the systematic use of the Schwinger representation, by virtue of which two boson fields are equivalent to an effective spin, for casting multimode squeezed states into multipartite spin entangled states. The motivation for this endeavor ... More
Folded Fields as the Source of Extreme Radio-Wave Scattering in the Galactic CenterFeb 24 2006A strong case has been made that radio waves from sources within about half a degree of the Galactic Center undergo extreme diffractive scattering. However, problems arise when standard (``Kolmogorov'') models of electron density fluctuations are employed ... More
Recovery of transverse velocities of steadily rotating patterns in flat galaxiesApr 15 2003Jul 02 2003The transverse velocities of steadily rotating, non--axisymmetric patterns in flat galaxies may be determined by a purely kinematical method, using two dimensional maps of a tracer surface brightness and radial current density. The data--maps could be ... More
Stellar Dynamics around Black Holes in Galactic NucleiNov 19 1998We classify orbits of stars that are bound to central black holes in galactic nuclei. The stars move under the combined gravitational influences of the black hole and the central star cluster. Within the sphere of influence of the black hole, the orbital ... More
Colour-octet Contributions to $x_F$ Distributions in $J/ψ$ Hadro-production at Fixed Target EnergiesAug 24 1996Sep 09 1996We study J/\psi production at fixed-target energies, including the colour-octet production mechanisms predicted by NRQCD. In an earlier paper, we found that the octet components were crucial in understanding p_T-integrated forward (x_F > 0) cross-sections. ... More
Recursions, formulas, and graph-theoretic interpretations of ramified coverings of the sphere by surfaces of genus 0 and 1Dec 17 1998We derive a closed-form expression for all genus 1 Hurwitz numbers, and give a simple new graph-theoretic interpretation of Hurwitz numbers in genus 0 and 1. (Hurwitz numbers essentially count irreducible genus g covers of the sphere, with arbitrary specified ... More
Active Model Aggregation via Stochastic Mirror DescentMar 28 2015We consider the problem of learning convex aggregation of models, that is as good as the best convex aggregation, for the binary classification problem. Working in the stream based active learning setting, where the active learner has to make a decision ... More
A new $\operatorname{Gal}(\overline{\mathbb{Q}}/\mathbb{Q})$-invariant of dessins d'enfantsMar 30 2014Oct 02 2014We study the action of $\operatorname{Gal}(\overline{\mathbb{Q}}/\mathbb{Q})$ on the category of Belyi functions (finite, \'{e}tale covers of $\mathbb{P}^1_{\overline{\mathbb{Q}}}\setminus \{0,1,\infty\}$). We describe a new combinatorial $\operatorname{Gal}(\overline{\mathbb{Q}}/\mathbb{Q})$-invariant ... More
A Grothendieck-Lefschetz theorem for equivariant Picard groupsDec 21 2017We prove a Grothendieck-Lefschetz theorem for equivariant Picard groups of non-singular varieties with finite group actions.
Eigenvalues of non-reversible Markov chains: their connection to mixing timesApr 17 2006May 07 2007This paper originally showed a lower bound on mixing time for a non-reversible Markov chain in terms of its largest non-trivial eigenvalue, and used this to re-derive some generalizations of results of Fan Chung. However, the paper has been withdrawn ... More
Sharp edge, vertex, and mixed Cheeger type inequalities for finite Markov kernelsJun 07 2006May 05 2007We show how the evolving set methodology of Morris and Peres can be used to show Cheeger inequalities for bounding the spectral gap of a finite Markov kernel. This leads to sharp versions of several previous Cheeger inequalities, including ones involving ... More
Murphy's Law in algebraic geometry: Badly-behaved deformation spacesNov 22 2004We consider the question: ``How bad can the deformation space of an object be?'' The answer seems to be: ``Unless there is some a priori reason otherwise, the deformation space may be as bad as possible.'' We show this for a number of important moduli ... More
Duality and evolving set bounds on mixing timesJul 02 2006We sharpen the Evolving set methodology of Morris and Peres and extend it to study convergence in total variation, relative entropy, $L^2$ and other distances. Bounds in terms of a modified form of conductance are given which apply even for walks with ... More
Solving Society's Big Ills, A Small StepMar 19 2016Sep 26 2016We look at a collection of conjectures with the unifying message that smaller social systems, tend to be less complex and can be aligned better, towards fulfilling their intended objectives. We touch upon a framework, referred to as the four pronged approach ... More
Dynamic Multi-Factor Bid-Offer Adjustment Model: A Feedback Mechanism for Dealers (Market Makers) to Deal (Grapple) with the Uncertainty Principle of the Social SciencesJan 01 2016Feb 02 2016The author seeks to develop a model to alter the bid-offer spread, currently quoted by market makers, that varies with the market and trading conditions. The dynamic nature of financial markets and trading, as with the rest of social sciences, where changes ... More
The Circle of Investment: Connecting the Dots of the Portfolio Management Cycle...Mar 19 2016Mar 31 2016We will look at the entire cycle of the investment process relating to all aspects of, formulating an investment hypothesis, constructing a portfolio based on that, executing the trades to implement it, on-going risk management, periodically measuring ... More
A Tale of Two Consequences: Intended and Unintended Outcomes of the Japan TOPIX Tick Size ChangesFeb 02 2016May 21 2016We look at the effect of the tick size changes on the TOPIX 100 index names made by the Tokyo Stock Exchange on Jan-14-2014 and Jul-22-2104. The intended consequence of the change is price improvement and shorter time to execution. We look at security ... More
Fighting Uncertainty with UncertaintyJan 14 2016Jul 11 2016We can overcome uncertainty with uncertainty. Using randomness in our choices and in what we control and hence in the decision making process could potentially offset the uncertainty inherent in the environment and yield better outcomes. This methodology ... More
Genus g Gromov-Witten invariants of Del Pezzo surfaces: Counting plane curves with fixed multiple pointsSep 04 1997As another application of the degeneration methods of [V3], we count the number of irreducible degree $d$ geometric genus $g$ plane curves, with fixed multiple points on a conic $E$, not containing $E$, through an appropriate number of general points ... More
The characteristic numbers of quartic plane curvesDec 02 1998The characteristic numbers of smooth plane quartics are computed using intersection theory on a component of the moduli space of stable maps. This completes the verification of Zeuthen's prediction of characteristic numbers of smooth plane curves. A short ... More
Radio Interferometers with wide bandwidthsOct 08 2003The Australia Telescope Compact Array and the Very Large Array are currently being upgraded to operate with wide bandwidths; interferometers dedicated to the measurement of cosmic microwave background anisotropies are being designed with large instantaneous ... More
On a nonlocal extension of differentiationSep 17 2015Mar 21 2016We study an integral equation that extends the problem of anti-differentiation. We formulate this equation by replacing the classical derivative with a known nonlocal operator similar to those applied in fracture mechanics and nonlocal diffusion. We show ... More
Duality and evolving set bounds on mixing timesJul 02 2006Jun 01 2018This survey is an in-depth development of the theoretical aspects of the method of Evolving Sets, a method which has been used in several of my papers. It is fairly esoteric as to a large degree it stems from my efforts to ascertain whether Evolving sets ... More
A geometric Littlewood-Richardson ruleFeb 24 2003We describe an explicit geometric Littlewood-Richardson rule, interpreted as deforming the intersection of two Schubert varieties so that they break into Schubert varieties. There are no restrictions on the base field, and all multiplicities arising are ... More
Microstructure under the Microscope: Combining Dimension Reduction, Distance Measures and CovarianceMar 30 2016May 04 2016Market Microstructure is the investigation of the process and protocols that govern the exchange of assets with the objective of reducing frictions that can impede the transfer. In financial markets, where there is an abundance of recorded information, ... More
ATCA and CMB anisotropiesAug 27 2001Australia Telescope Compact Array (ATCA) observations in sky regions selected to be low in foreground confusion have been used to infer limits on arcmin-scale CMB anisotropy in total intensity and polarization. These deep searches have, hitherto, been ... More
Vertex and edge expansion properties for rapid mixingOct 26 2004We show a strict hierarchy among various edge and vertex expansion properties of Markov chains. This gives easy proofs of a range of bounds, both classical and new, on chi-square distance, spectral gap and mixing time. The 2-gradient is then used to give ... More
An invariant in shock clustering and Burgers turbulenceJun 15 2011Jan 06 20121-D scalar conservation laws with convex flux and Markov initial data are now known to yield a completely integrable Hamiltonian system. In this article, we rederive the analogue of Loitsiansky's invariant in hydrodynamic turbulence from the perspective ... More
Financial Services, Economic Growth and Well-Being: A Four-Pronged StudyMar 03 2016A four-pronged approach to dealing with Social Science Phenomenon is outlined. This methodology is applied to Financial Services, Economic Growth and Well-Being. The four prongs are like the four directions for an army general looking for victory. Just ... More
Securities Lending Strategies, Exclusive Auction BidsMar 03 2016May 09 2016The objective is either to design an appropriate securities lending auction mechanism or to come up with a strategy for placing bids, depending on which side of the fence a participant sits. There are two pieces to this puzzle. One is the valuation of ... More
Promising outcomes of an online course in research writing at a Rwandan universityOct 05 2012Background: Researchers in developing countries often do not have access to training on research writing. The purpose of this study was to test whether researchers in Rwanda might complete and benefit from a pilot online course in research writing. Methods: ... More
Rates of convergence for Smoluchowski's coagulation equationsMay 21 2009Apr 24 2011We establish nearly optimal rates of convergence to self-similar solutions of Smoluchowski's coagulation equation with kernels $K = 2$, $x + y$, and $xy$. The method is a simple analogue of the Berry-Ess\'een theorem in classical probability and requires ... More
On an Inequality of Dimension-like Invariants for Finite GroupsFeb 02 2015In this paper, we introduce several notions of "dimension" of a finite group, involving sizes of generating sets and certain configurations of maximal subgroups. We focus on the inequality $m(G) \leq \mathrm{MaxDim}(G)$, giving a family of examples where ... More
The moduli space of curves and Gromov-Witten theoryFeb 16 2006Feb 20 2006The goal of this article is to motivate and describe how Gromov-Witten theory can and has provided tools to understand the moduli space of curves. For example, ideas and methods from Gromov-Witten theory have led to both conjectures and theorems showing ... More
Intersection conductance and canonical alternating paths, methods for general finite Markov chainsNov 19 2006Dec 05 2011We extend the conductance and canonical paths methods to the setting of general finite Markov chains, including non-reversible non-lazy walks. The new path method is used to show that a known bound for mixing time of a lazy walk on a Cayley graph with ... More
Securities Lending Strategies, Valuation of Term Loans using Option TheorySep 06 2016Sep 19 2016We develop models to price long term loans in the securities lending business. These longer horizon deals can be viewed as contracts with optionality embedded in them and can be priced using established methods from derivatives theory, becoming to our ... More
Counting curves of any genus on rational ruled surfacesSep 04 1997In this paper we study the geometry of the Severi varieties parametrizing curves on the rational ruled surface $\fn$. We compute the number of such curves through the appropriate number of fixed general points on $\fn$, and the number of such curves which ... More
David vs Goliath (You against the Markets), A Dynamic Programming Approach to Separate the Impact and Timing of Trading CostsMar 03 2016May 31 2016To trade, or not to trade, that is the question Whether an optimizer can yield the answer Against the spikes and crashes of markets gone wild. To quench one's thirst before liquidity runs dry Or wait till the tide of momentum turns mild. A trader's conundrum ... More
Securities Lending Strategies, Valuation of Term Loans using Option TheorySep 06 2016Nov 06 2016We develop models to price long term loans in the securities lending business. These longer horizon deals can be viewed as contracts with optionality embedded in them and can be priced using established methods from derivatives theory, becoming to our ... More
Solving the Equity Risk Premium Puzzle and Inching Towards a Theory of EverythingApr 17 2016May 31 2016The equity risk premium puzzle is that the return on equities has far exceeded the average return on short-term risk-free debt and cannot be explained by conventional representative-agent consumption based equilibrium models. We review a few attempts ... More
Infinitely ramified Galois representationsMar 01 2000In this paper we show how to construct, for most p >= 5, two types of surjective representations \rho:G_Q=Gal(\bar{Q}/Q) -> GL_2(Z_p) that are ramified at an infinite number of primes. The image of inertia at almost all of these primes will be torsion-free. ... More
Observing the CMB with the AMiBAJul 19 2001I discuss the capabilities and limitations of the AMiBA for imaging CMB anisotropies. Michael Kesteven (ATNF-CSIRO) has proposed drift-scanning as an observing strategy for measuring and rejecting any instrumental response that the close-packed interferometers ... More
A sharp isoperimetric bound for convex bodiesOct 31 2004We consider the problem of lower bounding a generalized Minkowski measure of subsets of a convex body with a log-concave probability measure, conditioned on the set size. A bound is given in terms of diameter and set size, which is sharp for all set sizes, ... More
Pre-Trained Convolutional Neural Network Features for Facial Expression RecognitionDec 16 2018Facial expression recognition has been an active area in computer vision with application areas including animation, social robots, personalized banking, etc. In this study, we explore the problem of image classification for detecting facial expressions ... More
Twelve points on the projective line, branched covers, and rational elliptic fibrationsOct 14 1999The following divisors in the space Sym^{12} P^1 of twelve points on P^1 are actually the same: (A) the possible locus of the twelve nodal fibers in a rational elliptic fibration (i.e. a pencil of plane cubic curves); (B) degree 12 binary forms that can ... More
Enumerative geometry of plane curves of low genusMar 02 1998We collect various known results (about plane curves and the moduli space of stable maps) to derive new recursive formulas enumerating low genus plane curves of any degree with various behaviors. Recursive formulas are given for the characteristic numbers ... More
The simple random walk and max-degree walk on a directed graphSep 11 2006We show bounds on total variation and $L^{\infty}$ mixing times, spectral gap and magnitudes of the complex valued eigenvalues of a general (non-reversible non-lazy) Markov chain with a minor expansion property. This leads to the first known bounds for ... More
eta_c production at the Large Hadron ColliderJul 29 2010We have studied the production of the 1S_0 charmonium state, eta_c, at the Large Hadron Collider (LHC) in the framework of Non-Relativistic Quantum Chromodynamics (NRQCD) using heavy-quark symmetry. We find that NRQCD predicts a large production cross-section ... More
QCD calculation of J/psi+gamma mass distributionsAug 11 1993We compute the J/psi+gamma invariant-mass distributions from the QCD subprocess g + g --> J/psi+gamma. At large masses, this subprocess is the dominant mechanism for J/psi+gamma production, and data could provide a good test of QCD. The mass distribution ... More
Transport coefficients for the shear dynamo problem at small Reynolds numbersMar 14 2010May 13 2011We build on the formulation developed in Sridhar & Singh (JFM, 664, 265, 2010), and present a theory of the \emph{shear dynamo problem} for small magnetic and fluid Reynolds numbers, but for arbitrary values of the shear parameter. Specializing to the ... More
J/psi+gamma Production at the Tevatron EnergyJul 27 1994We study the process $\bar p p \rightarrow J/\psi + \gamma +X$ at the Tevatron energy ($\sqrt{s} = 1.8$~TeV). The perturbative QCD contributions to this process from the gluon-fusion and the fragmentation mechanisms are computed. For the entire range ... More
Migration into a Companion's Trap: Disruption of Multiplanet Systems in BinariesSep 15 2015Most exoplanetary systems in binary stars are of S--type, and consist of one or more planets orbiting a primary star with a wide binary stellar companion. Gravitational forcing of a single planet by a sufficiently inclined binary orbit can induce large ... More
Stellar Dynamics around a Massive Black Hole I: Secular Collisionless TheorySep 08 2015Mar 06 2016We present a theory in three parts, of the secular dynamics of a (Keplerian) stellar system of mass $M$ orbiting a black hole of mass $M_\bullet \gg M$. Here we describe the collisionless dynamics; Papers II and III are on the (collisional) theory of ... More
Stellar Dynamics around a Massive Black Hole III: Resonant Relaxation of Axisymmetric DiscsFeb 18 2016We study the Resonant Relaxation (RR) of an axisymmetric low mass (or Keplerian) stellar disc orbiting a more massive black hole (MBH). Our recent work on the general kinetic theory of RR is simplified in the standard manner by ignoring the effects of ... More
Slow m=1 instabilities of softened gravity Keplerian discsNov 11 2009We present the simplest model that permits a largely analytical exploration of the m=1 counter-rotating instability in a "hot" nearly Keplerian disc of collisionless self-gravitating matter. The model consists of a two-component softened gravity disc, ... More
Bees with attitude: the effect of gusts on flight dynamicsFeb 10 2018Flight is a complicated task at small scales in part due to the ubiquitous unsteady air which contains it. Flying organisms deal with these difficulties using active and passive control mechanisms to steer their body motion. Body attitudes of flapping ... More
Bumblebees minimize control challenges by combining active and passive modes in unsteady windsMar 01 2016Mar 02 2016The natural wind environment that volant insects encounter is unsteady and highly complex, posing significant flight control and stability challenges. Unsteady airflows can range from structured chains of discrete vortices shed in the wake of an object ... More
Shear thinning in dilute and semidilute solutions of polystyrene and DNAOct 23 2017May 06 2018The viscosity of dilute and semidilute unentangled DNA solutions, in steady simple shear flow, has been measured across a range of temperatures and concentrations. For polystyrene solutions, measurements of viscosity have been carried out in the semidilute ... More
Effect of stretching-induced changes in hydrodynamic screening on coil-stretch hysteresis of unentangled polymer solutionsSep 07 2016Extensional rheometry and Brownian Dynamics simulations of flexible polymer solutions confirm predictions based on blob concepts that coil--stretch hysteresis in extensional flows increases with concentration, reaching a maximum at the critical overlap ... More
Universal solvent quality crossover of the zero shear rate viscosity of semidilute DNA solutionsDec 16 2011Dec 19 2013The scaling behaviour of the zero shear rate viscosity of semidilute unentangled DNA solutions, in the double crossover regime driven by temperature and concentration, is mapped out by systematic experiments. The viscosity is shown to have a power law ... More
Constrained Violent Relaxation to a Spherical HaloJun 08 1999Violent relaxation during the collapse of a galaxy halo is known to be incomplete in realistic cases such as cosmological infall or mergers. We adopt a physical picture of strong but short lived interactions between potential fluctuations and particle ... More
Using Noisy Extractions to Discover Causal KnowledgeNov 16 2017Knowledge bases (KB) constructed through information extraction from text play an important role in query answering and reasoning. In this work, we study a particular reasoning task, the problem of discovering causal relationships between entities, known ... More
Elucidation of molecular targets of bioactive principles of black cumin relevant to its anti-tumour functionality - An Insilico target fishing approachFeb 20 2015Black cumin (Nigella sativa) is a spice having medicinal properties with pungent and bitter odour. It is used since thousands of years to treat various ailments, including cancer mainly in South Asia and Middle Eastern regions. Substantial evidence in ... More
Resonant slepton production at the LHC in models with an ultralight gravitinoNov 20 2003Mar 12 2004We examine resonant slepton production at the LHC with gravitinos in the final state. The slepton undergoes gauge decay into a neutralino and a lepton, the neutralino decays into a photon and a gravitino. By measuring the transverse masses of the gamma- ... More
Efficient Kernel Fusion Techniques for Massive Video Data Analysis on GPGPUsSep 15 2015Kernels are executable code segments and kernel fusion is a technique for combing the segments in a coherent manner to improve execution time. For the first time, we have developed a technique to fuse image processing kernels to be executed on GPGPUs ... More
Non-linear microwave impedance of short and long Josephson JunctionsOct 26 1998The non-linear dependence on applied $ac$ field ($b_{\omega}$) or current ($% i_{\omega}$) of the microwave (ac) impedance $R_{\omega}+iX_{\omega}$ of both short and long Josephson junctions is calculated under a variety of excitation conditions. The ... More
Unstable $m=1$ modes of counter-rotating Keplerian discsMar 10 2012We study the linear $m=1$ counter-rotating instability in a two-component, nearly Keplerian disc. Our goal is to understand these \emph{slow} modes in discs orbiting massive black holes in galactic nuclei. They are of interest not only because they are ... More
Non-perturbative unification in the light of LEP resultsJun 14 1993We consider an alternative to conventional GUTs originally proposed by Maiani, Parisi and Petronzio, where owing to the existence of extra fermion generations at some intermediate scale, the gauge couplings become large at high energies. We first comment ... More
Magnetic fields on a wide range of scales in star-forming galaxiesMar 15 2016Mar 23 2016A key ingredient in the evolution of galaxies is the star formation cycle. Recent progress in the study of magnetic fields is revealing the close connection between star formation and its effect on the small-scale structure in the magnetized interstellar ... More
Network Topology Mapping from Partial Virtual Coordinates and Graph GeodesicsDec 28 2017Sep 13 2018For many important network types (e.g., sensor networks in complex harsh environments and social networks) physical coordinate systems (e.g., Cartesian), and physical distances (e.g., Euclidean), are either difficult to discern or inappropriate. Accordingly, ... More
Explaining Anomalous CDF mu gamma Missing-E_T Events With SupersymmetryNov 01 2001May 22 2002CDF recently reported an excess of events in the mu-gamma-missing E_T channel that disagrees with the Standard Model prediction. No such excess was observed in the e-gamma-mett channel. We explain the excess via resonant smuon production with a single ... More
Experimental studies of Chaos and Localization in Quantum WavefunctionsApr 21 1995Wavefunctions in chaotic and disordered quantum billiards are studied experimentally using thin microwave cavities. The chaotic wavefunctions display universal density distributions and density auto-correlations in agreement with expressions derived fro ... More
Generalizing the Splits Equivalence Theorem and Four Gamete Condition: Perfect Phylogeny on Three State CharactersMay 09 2009Sep 18 2009We study the perfect phylogeny problem and establish a generalization of the four gamete condition (also called the Splits Equivalence Theorem) for sequences over three state characters. Our main result is that a set of input sequences over three state ... More
Geometry of two-qubit states with negative conditional entropySep 14 2016We review the geometric features of negative conditional entropy and the properties of the conditional amplitude operator proposed by Cerf and Adami for two qubit states in comparison with entanglement and nonlocality of the states. We identify the region ... More
CD-PHY: Physical Layer Security in Wireless Networks through Constellation DiversityAug 25 2011A common approach for introducing security at the physical layer is to rely on the channel variations of the wireless environment. This type of approach is not always suitable for wireless networks where the channel remains static for most of the network ... More
Pursuing the Strange Stop Interpretation of the HERA Large Q^2 dataMay 25 1997We explore the possible interpretation of the large-$Q^2$ anomaly reported by the H1 and ZEUS collaborations in terms of stop squark production off a strange quark in the proton via an R-violating interaction. This "strange stop" interpretation is constrained ... More
Bounds on the Masses and Couplings of Leptoquarks from Leptonic Partial Widths of the ZJun 21 1994The vertex corrections to the leptonic partial widths of the $Z$ induced by leptoquarks that couple leptons to the top quark are considered. We obtain stringent bounds on the parameter space of the masses and Yukawa couplings of these leptoquarks, using ... More
Dependence of Residual Rotation Measure (RRM) on Intervening MgII Absorbers at Cosmic DistancesJul 10 2013We investigate the dependence of residual rotation measure (RRM) on intervening absorption systems at cosmic distances by using a large sample of 539 SDSS quasars in conjunction with the available rotation measure catalog at around 21cm wavelength. We ... More
Local Support Vector Machines:Formulation and AnalysisSep 14 2013We provide a formulation for Local Support Vector Machines (LSVMs) that generalizes previous formulations, and brings out the explicit connections to local polynomial learning used in nonparametric estimation literature. We investigate the simplest type ... More
The Generalized Poisson distribution and a model of clustering from Poisson initial conditionsMar 05 1998This paper presents a new derivation of the Generalized Poisson distribution. This distribution provides a good fit to the evolved, counts-in-cells distribution measured in numerical simulations of hierarchical clustering from Poisson initial conditions. ... More
Constrained realizations and minimum variance reconstruction of non-Gaussian random fieldsNov 21 1995With appropriate modifications, the Hoffman--Ribak algorithm that constructs constrained realizations of Gaussian random fields having the correct ensemble properties can also be used to construct constrained realizations of those non-Gaussian random ... More
Dependence Balance Based Outer Bounds for Gaussian Networks with Cooperation and FeedbackDec 10 2008Dec 19 2008We obtain new outer bounds on the capacity regions of the two-user multiple access channel with generalized feedback (MAC-GF) and the two-user interference channel with generalized feedback (IC-GF). These outer bounds are based on the idea of dependence ... More