Results for "Spyros Angelopoulos"

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Further Connections Between Contract-Scheduling and Ray-Searching ProblemsApr 27 2015This paper addresses two classes of different, yet interrelated optimization problems. The first class of problems involves a robot that must locate a hidden target in an environment that consists of a set of concurrent rays. The second class pertains ... More
Online Computation with Untrusted AdviceMay 14 2019The advice model of online computation captures the setting in which the online algorithm is given some partial information concerning the request sequence. This paradigm allows to establish tradeoffs between the amount of this additional information ... More
Interruptible Algorithms for Multiproblem SolvingOct 26 2018In this paper we address the problem of designing an interruptible system in a setting in which $n$ problem instances, all equally important, must be solved concurrently. The system involves scheduling executions of contract algorithms (which offer a ... More
The expanding search ratio of a graphFeb 18 2016We study the problem of searching for a hidden target in an environment that is modeled by an edge-weighted graph. A sequence of edges is chosen starting from a given {\em root} vertex such that each edge is adjacent to a previously chosen edge. This ... More
Primal-dual and dual-fitting analysis of online scheduling algorithms for generalized flow-time problemsFeb 13 2015Jul 08 2015We study online scheduling problems on a single processor that can be viewed as extensions of the well-studied problem of minimizing total weighted flow time. In particular, we provide a framework of analysis that is derived by duality properties, does ... More
Online Maximum Matching with RecourseJan 10 2018May 07 2018We study the online maximum matching problem in a model in which the edges are associated with a known recourse parameter $k$. An online algorithm for this problem has to maintain a valid matching while edges of the underlying graph are presented one ... More
Best-of-two-worlds analysis of online searchOct 18 2018In search problems, a mobile searcher seeks to locate a target that hides in some unknown position of the environment. Such problems are typically considered to be of an on-line nature, in that the input is unknown to the searcher, and the performance ... More
Stochastic dominance and the bijective ratio of online algorithmsJul 20 2016Stochastic dominance is a technique for evaluating the performance of online algorithms that provides an intuitive, yet powerful stochastic order between the compared algorithms. Accordingly this holds for bijective analysis, which can be interpreted ... More
Nonlinear Wave Equations With Null Condition On Extremal Reissner-Nordström Spacetimes I: Spherical SymmetryAug 19 2014We study spherically symmetric solutions of semilinear wave equations in the case where the nonlinearity satisfies the null condition on extremal Reissner--Nordstrom black hole spacetimes. We show that solutions which arise from sufficiently small compactly ... More
Well-posedness and ill-posedness results for the Novikov-Veselov equationJul 15 2013In this paper we study the Novikov-Veselov equation and the related modified Novikov-Veselov equation in certain Sobolev spaces. We prove local well-posedness in H^s (R2) for s > 1/2 for the Novikov-Veselov equation, and local well-posedness in H^s (R2) ... More
Markov Chain Monte Carlo using Tree-Based Priors on Model StructureJan 10 2013We present a general framework for defining priors on model structure and sampling from the posterior using the Metropolis-Hastings algorithm. The key idea is that structure priors are defined via a probability tree and that the proposal mechanism for ... More
An extensible web interface for databases and its application to storing biochemical dataSep 20 2010This paper presents a generic web-based database interface implemented in Prolog. We discuss the advantages of the implementation platform and demonstrate the system's applicability in providing access to integrated biochemical data. Our system exploits ... More
Unique continuation for the vacuum Einstein equationsFeb 06 2009Sep 02 2009We derive a unique continuation theorem for the vacuum Einstein equations. Our method of proof utilizes Carleman estimates (most importantly one obtained recently by Ionescu and Klainerman), but also relies strongly on certain geometric gauge constructions ... More
The Penrose inequality on perturbations of the Schwarzschild exteriorJun 21 2015We prove a version the Penrose inequality for black hole space-times which are perturbations of the Schwarzschild exterior in a slab around a null hypersurface $\underline{\mathcal{N}}_0$. $\underline{\mathcal{N}}_0$ terminates at past null infinity $\mathcal{I}^-$ ... More
The decomposition of Global Conformal Invariants I: On a conjecture of Deser and SchwimmerNov 11 2007Dec 18 2009This is the first in a series of papers where we prove a conjecture of Deser and Schwimmer regarding the algebraic structure of ``global confor- mal invariants"; these are defined to be conformally invariant integrals of geometric scalars. The conjecture ... More
An explanation of unexpected Hoxd expressions in mutant miceSep 03 2012The Hox gene collinearity enigma has often been approached using models based on biomolecular mechanisms. The biophysical model, is an alternative approach, speculating that collinearity is caused by physical forces pulling the Hox clusters from a territory ... More
The Decomposition of Global Conformal Invariants: Some Technical Proofs. IDec 18 2009Feb 26 2011This paper forms part of a larger work where we prove a conjecture of Deser and Schwimmer regarding the algebraic structure of "global conformal invariants"; these are defined to be conformally invariant integrals of geometric scalars. The conjecture ... More
The decomposition of global conformal invariants IV: A proposition on local Riemannian invariantsDec 18 2009This is the fourth in a series of papers where we prove a conjecture of Deser and Schwimmer regarding the algebraic structure of ``global conformal invariants''; these are defined to be conformally invariant integrals of geometric scalars. The conjecture ... More
On the decomposition of global conformal invariants IISep 23 2005Mar 26 2006This paper is a continuation of [2], where we complete our partial proof of the Deser-Schwimmer conjecture on the structure of ``global conformal invariants''. Our theorem deals with such invariants P(g^n) that locally depend only on the curvature tensor ... More
Constraints on Cosmological and Biasing models using AGN clusteringApr 27 2001We attempt to put constraints on different cosmological and biasing models by combining the recent clustering results of X-ray sources in the local ($z\le 0.1$) and distant universe ($z\sim 1$). To this end we compare the measured angular correlation ... More
Linear growth in power law $f(T)$ gravityMar 31 2016Apr 06 2016We provide for the first time the growth index of linear matter fluctuations of the power law $f(T) \propto (-T)^{b}$ gravity model. We find that the asymptotic form of this particular $f(T)$ model is $\gamma \approx \frac{6}{11-6b}$ which obviously extends ... More
The $Λ$CDM growth rate of structure revisitedFeb 08 2012Jun 26 2012We re-examine the growth index of the concordance $\Lambda$ cosmology in the light of the latest 6dF and {\em WiggleZ} data. In particular, we investigate five different models for the growth index $\gamma$, by comparing their cosmological evolution using ... More
The Physical Properties of the Cosmic AccelerationJan 12 2010Jan 21 2010The observed late-time acceleration of the cosmic expansion constitutes a fundamental problem in modern theoretical physics and cosmology. In an attempt to weight the validity of a large number of dark energy models, I use the recent measurements of the ... More
The growth index of matter perturbations using the clustering of dark energyDec 06 2014Feb 23 2015We have put forward a new unified framework which provides a consistent and rather complete account of the growth index of matter perturbations in the regime where the dark energy is allowed to have clustering. In particular, we find that the growth index ... More
Cosmological implications and structure formation from a time varying vacuumMar 03 2009We study the dynamics of the FLRW flat cosmological models in which the vacuum energy varies with time, $\Lambda(t)$. In this model we find that the main cosmological functions such as the scale factor of the universe and the Hubble flow are defined in ... More
The decomposition of Global Conformal Invariants VDec 18 2009This is the fifth in a series of papers where we prove a conjecture of Deser and Schwimmer regarding the algebraic structure of ``global conformal invariants''; these are defined to be conformally invariant integrals of geometric scalars. The conjecture ... More
Shape Statistics of Sloan Digital Survey superclustersFeb 28 2003Jun 03 2003We study the supercluster shape properties of the recently compiled SDSS cluster catalog using an approach based on differential geometry. We detect superclusters by applying the percolation algorithm to observed cluster populations, extended out to $z_{\rm ... More
Cosmological parameters from the clustering of AGNJul 23 2001We attempt to put constraints on different cosmological and biasing models by combining the recent clustering results of X-ray sources in the local ($z\le 0.1$) and distant universe ($z\sim 1$).
Solving the main cosmological puzzles with a generalized time varying vacuum energyJan 21 2009Oct 12 2009We study the dynamics of the FLRW flat cosmological models in which the vacuum energy density varies with time, $\Lambda(t)$. In particular, we investigate the dynamical properties of a generalized vacuum model and we find that under certain conditions ... More
The decomposition of global conformal invariants II: The Fefferman-Graham ambient metric and the nature of the decompositionDec 18 2009This is the second in a series of papers where we prove a conjecture of Deser and Schwimmer regarding the algebraic structure of ``global conformal invariants''; these are defined to be conformally invariant integrals of geometric scalars. The conjecture ... More
Equilibration in one-dimensional quantum hydrodynamic systemsDec 01 2016We study quench dynamics and equilibration in one-dimensional quantum hydrodynamics, which provides effective descriptions of the density and velocity fields in gapless quantum gases. We show that the information content of the large time steady state ... More
On conformally invariant differential operatorsAug 31 2006Mar 29 2007We construct new families of conformally invariant differential operators acting on densities. We introduce a simple, direct approach which shows that all such operators arise via this construction when the degree is bounded by the dimension. The method ... More
On the decomposition of global conformal invariants ISep 23 2005Mar 26 2006This is the first of two papers where we address and partially confirm a conjecture of Deser and Schwimmer, originally postulated in high energy physics. The objects of study are scalar Riemannian quantities constructed out of the curvature and its covariant ... More
Cosmic expansion and structure formation in running vacuum cosmologiesJan 15 2015Jan 16 2015We investigate the dynamics of the FLRW flat cosmological models in which the vacuum energy varies with redshift. A particularly well motivated model of this type is the so-called quantum field vacuum, in which both kind of terms $H^{2}$ and constant ... More
Theoretical and Observational Constraints on Brane Inflation and Study of Scalar Perturbations through the Effective Field Theory FormalismJun 04 2014In this thesis, consisting of two main parts, we study observational signatures of cosmic (super)strings in the context of D-brane inflation and properties of scalar perturbations on generic homogeneous inflating backgrounds. In the first part we study ... More
Memory-preserving equilibration after a quantum quench in a 1d critical modelJul 28 2015Sep 09 2016One of the fundamental principles of statistical physics is that only partial information about a system's state is required for its macroscopic description. This is not only true for thermal ensembles, but also for the unconventional ensemble, known ... More
The decomposition of global conformal invariants VI: The proof of the proposition on local Riemannian invariantsDec 18 2009This is the last in a series of papers where we prove a conjecture of Deser and Schwimmer regarding the algebraic structure of ``global conformal invariants''; these are defined to be conformally invariant integrals of geometric scalars. The conjecture ... More
Preferential Acceleration of Coherent Magnetic Structures and Bursty Bulk Flows in Earth's MagnetotailJun 28 2001Observations indicate that the magnetotail convection is turbulent and bi-modal, consisting of fast bursty bulk flows (BBF) and a nearly stagnant background. We demonstrate that this observed phenomenon may be understood in terms of the intermittent interactions, ... More
Late-time asymptotics for the wave equation on spherically symmetric, stationary spacetimesDec 05 2016Feb 15 2018We derive precise late-time asymptotics for solutions to the wave equation on spherically symmetric, stationary and asymptotically flat spacetimes including as special cases the Schwarzschild and Reissner-Nordstrom families of black holes. We also obtain ... More
Asymptotic blow-up for a class of semilinear wave equations on extremal Reissner-Nordström spacetimesDec 05 2016Feb 15 2018We prove small data global existence for a class of semilinear wave equations satisfying the null condition on extremal Reissner-Nordstrom black hole backgrounds with nonlinear terms that degenerate at the event horizon. We impose no symmetry assumptions. ... More
A vector field approach to almost-sharp decay for the wave equation on spherically symmetric, stationary spacetimesDec 05 2016We present a new vector field approach to almost-sharp decay for the wave equation on spherically symmetric, stationary and asymptotically flat spacetimes. Specifically, we derive a new hierarchy of higher-order weighted energy estimates by employing ... More
Logarithmic corrections in the asymptotic expansion for the radiation field along null infinityDec 28 2017We obtain the second-order asymptotics for the radiation field of spherically symmetric solutions to the wave equation on spherically symmetric and asymptotically flat backgrounds including the Schwarzschild and sub-extremal Reissner-Nordstrom families ... More
The trapping effect on degenerate horizonsDec 30 2015We show that degenerate horizons exhibit a new trapping effect. Specifically, we obtain a non-degenerate Morawetz estimate for the wave equation in the domain of outer communications of extremal Reissner-Nordstrom up to and including the future event ... More
Invariant measures for integrable spin chains and integrable discrete NLSJul 23 2018We consider discrete analogues of two well-known open problems regarding invariant measures for dispersive PDE, namely, the invariance of the Gibbs measure for the continuum (classical) Heisenberg model and the invariance of white noise under focusing ... More
The growth index of matter perturbations and modified gravityMar 30 2012May 08 2012We place tight constraints on the growth index $\gamma$ by using the recent growth history results of 2dFGRS, SDSS-LRG, VIMOS-VLT deep Survey (VVDS) and {\em WiggleZ} datasets. In particular, we investigate several parametrizations of the growth index ... More
Cosmology from XMM High-Z AGN ClusteringJan 24 2007We review the high-redshift X-ray selected AGN clustering, based on the XMM/2dF survey, and compare it with other recent XMM-based results. Using the recent Hasinger et al. (2005) and La Franca et al. (2005) luminosity functions we find that the spatial ... More
Precision Cosmology from X-ray AGN clusteringSep 22 2009We place tight constraints on the main cosmological parameters of spatially flat cosmological models by using the recent angular clustering results of XMM-{\it Newton} soft (0.5-2 keV) X-ray sources (Ebrero et al. 2009a), which have a redshift distribution ... More
Convex Relaxations of Probabilistic AC Optimal Power Flow for Interconnected AC and HVDC GridsMar 30 2018Jan 28 2019High Voltage Direct Current (HVDC) systems interconnect AC grids to increase reliability, connect offshore wind generation, and enable coupling of electricity markets. Considering the growing uncertainty in power infeed and the complexity introduced by ... More
Entropic-force dark energy reconsideredFeb 26 2014May 21 2014We reconsider the entropic-force model in which both kind of Hubble terms ${\dot H}$ and $H^{2}$ appear in the effective dark energy (DE) density affecting the evolution of the main cosmological functions, namely the scale factor, deceleration parameter, ... More
Complete Willmore surfaces in H3 with bounded energy: boundary regularity and bubblingApr 23 2012Jul 29 2013We study various aspects related to boundary regularity of complete properly embedded Willmore surfaces in H3, particularly those related to assumptions on boundedness or smallness of a certain weighted version of the Willmore energy. We prove, in particular, ... More
Constraining the CDM spectrum normalization in flat dark energy cosmologiesJul 05 2006Aug 28 2006We study the relation between the rms mass fluctuations on 8$h^{-1}$Mpc scales and $\Omega_{\rm m}$ using the recent clustering results of XMM-{\it Newton} soft (0.5-2 keV) X-ray sources, which have a median redshift of $z\sim 1.2$. The relation can be ... More
The PSCz Dipole RevisitedSep 18 2006We re-examine the gravitational acceleration (dipole) induced on the Local Group of galaxies by the Infrared Astronomical Satellite (IRAS) galaxy distribution of the Point Source Catalogue redshift survey (PSCz). We treat the cirrus-affected low galactic ... More
Cosmological Implications of the PSCz PDF and its MomentsSep 07 2001Oct 17 2001We compare the {\em pdf} and its low-order moments (variance and skewness) of the smoothed PSCz galaxy density field and of the corresponding simulated PSCz look-alikes, generated from N-body simulations of 6 different DM models; four structure normalized ... More
Attend Refine Repeat: Active Box Proposal Generation via In-Out LocalizationJun 14 2016The problem of computing category agnostic bounding box proposals is utilized as a core component in many computer vision tasks and thus has lately attracted a lot of attention. In this work we propose a new approach to tackle this problem that is based ... More
Quasi locality of the GGE in interacting-to-free quenches in relativistic field theoriesAug 02 2016We study the quench dynamics in continuous relativistic quantum field theory, more specifically the locality properties of the large time stationary state. After a quantum quench in a one-dimensional integrable model, the expectation values of local observables ... More
Cluster expansion for ground states of local HamiltoniansJan 11 2016May 13 2016A central problem in many-body quantum physics is the determination of the ground state of a thermodynamically large physical system. We construct a cluster expansion for ground states of local Hamiltonians, which naturally incorporates physical requirements ... More
The tension of cosmological magnetic fields as a contribution to dark energyMay 14 2007We propose that cosmological magnetic fields generated in regions of finite spatial dimensions may manifest themselves in the global dynamics of the Universe as `dark energy'. We test our model in the context of spatially flat cosmological models by assuming ... More
Quench echo and work statistics in integrable quantum field theoriesMar 28 2014Feb 16 2015We propose a boundary thermodynamic Bethe ansatz calculation technique to obtain the Loschmidt echo and the statistics of the work done when a global quantum quench is performed on an integrable quantum field theory. We derive an analytic expression for ... More
Late-time asymptotics for the wave equation on spherically symmetric, stationary spacetimesDec 05 2016We derive precise late-time asymptotics for solutions to the wave equation on spherically symmetric, stationary and asymptotically flat spacetimes including as special cases the Schwarzschild and Reissner-Nordstrom families of black holes. We also obtain ... More
Horizon hair of extremal black holes and measurements at null infinitySep 26 2018It is shown that the conserved charges on the event horizon and the Cauchy horizon associated to scalar perturbations on extremal black holes are externally measurable from null infinity. This suggests that these charges have the potential to serve as ... More
Validity of the GGE for quantum quenches from interacting to noninteracting modelsMar 28 2014May 28 2014In the majority of the analytical verifications of the conjecture that the Generalised Gibbs Ensemble describes the large time asymptotics of local observables in quantum quench problems, both the post-quench and the pre-quench Hamiltonians are essentially ... More
Interacting Dark Matter as an Alternative to Dark EnergyNov 12 2009We investigate the global dynamics of the universe within the framework of the Interacting Dark Matter (IDM) scenario. Considering that the dark matter obeys the collisional Boltzmann equation, we can obtain analytical solutions of the global density ... More
Cosmological Evolution of Linear BiasNov 14 2000Using linear perturbation theory and the Friedmann-Lemaitre solutions of the cosmological field equations, we derive analytically a second-order differential equation for the evolution of the linear bias factor, b(z), between the background matter and ... More
Virialization of cosmological structures in models with time varying equation of stateOct 06 2006We study the virialization of the cosmic structures in the framework of flat cosmological models where the dark energy component plays an important role in the global dynamics of the universe. In particular, our analysis focuses on the study of the spherical ... More
Forecasting the cost of processing multi-join queries via hashing for main-memory databases (Extended version)Jul 11 2015Jul 21 2015Database management systems (DBMSs) carefully optimize complex multi-join queries to avoid expensive disk I/O. As servers today feature tens or hundreds of gigabytes of RAM, a significant fraction of many analytic databases becomes memory-resident. Even ... More
Towards Exascale Scientific Metadata ManagementMar 29 2015Advances in technology and computing hardware are enabling scientists from all areas of science to produce massive amounts of data using large-scale simulations or observational facilities. In this era of data deluge, effective coordination between the ... More
LocNet: Improving Localization Accuracy for Object DetectionNov 24 2015Apr 07 2016We propose a novel object localization methodology with the purpose of boosting the localization accuracy of state-of-the-art object detection systems. Our model, given a search region, aims at returning the bounding box of an object of interest inside ... More
Quantum quench in interacting field theory: a self-consistent approximationFeb 01 2010Apr 14 2010We study a composite quantum quench of the energy gap and the interactions in the interacting \phi^4 model using a self-consistent approximation. Firstly we review the results for free theories where a quantum quench of the energy gap or mass leads for ... More
Generating Classification Weights with GNN Denoising Autoencoders for Few-Shot LearningMay 03 2019Given an initial recognition model already trained on a set of base classes, the goal of this work is to develop a meta-model for few-shot learning. The meta-model, given as input some novel classes with few training examples per class, must properly ... More
Effective equation of state for running vacuum: "mirage" quintessence and phantom dark energyJul 17 2013Nov 04 2013Past analyses of the equation of state (EoS) of the Dark Energy (DE) were not incompatible with a phantom phase near our time. This has been the case in the years of WMAP observations, in combination with the remaining cosmological observables. Such situation ... More
Testing Eistein's gravity and dark energy with growth of matter perturbations: Indications for new Physics?Oct 01 2016The growth index of matter fluctuations is computed for ten distinct accelerating cosmological models and confronted to the latest growth rate data via a two-step process. First, we implement a joint statistical analysis in order to place constraints ... More
Object detection via a multi-region & semantic segmentation-aware CNN modelMay 07 2015Sep 23 2015We propose an object detection system that relies on a multi-region deep convolutional neural network (CNN) that also encodes semantic segmentation-aware features. The resulting CNN-based representation aims at capturing a diverse set of discriminative ... More
The Substructure-Alignment ConnectionNov 16 2001Nov 20 2001Using a sample of 903 APM clusters we investigate whether their dynamical status, as evidenced by the presence of significant substructures, is related to the large-scale structure of the Universe. We find that the cluster dynamical activity is strongly ... More
Effects of color reconnection on $t\bar{t}$ final states at the LHCJul 24 2014The modeling of color reconnection has become one of the dominant sources of systematic uncertainty in the top mass determination at hadron colliders. The uncertainty on the top mass due to color reconnection is conventionally estimated by taking the ... More
Logarithmic Conformal Field Theory Solutions of Two Dimensional MagnetohydrodynamicsFeb 03 1998Feb 09 1998We consider the application of logarithmic conformal field theory in finding solutions to the turbulent phases of 2-dimensional models of magnetohydrodynamics. These arise upon dimensional reduction of standard (infinite conductivity) 3-dimensional magnetohydrodynamics, ... More
Non-existence of time-periodic vacuum spacetimesApr 17 2015We prove that smooth asymptotically flat solutions to the Einstein vacuum equations which are assumed to be periodic in time, are in fact stationary in a neighborhood of infinity. Our result applies under physically relevant regularity assumptions purely ... More
Bounds on the Bondi Energy by a Flux of CurvatureAug 19 2013Aug 05 2016We consider smooth null cones in a vacuum spacetime that extend to future null infinity. For such cones that are perturbations of shear-free outgoing null cones in Schwarzschild spacetimes, we prove bounds for the Bondi energy, momentum, and rate of energy ... More
Global uniqueness theorems for linear and nonlinear wavesDec 04 2014Jul 24 2015We prove a unique continuation from infinity theorem for regular waves of the form $[ \Box + \mathcal{V} (t, x) ]\phi=0$. Under the assumption of no incoming and no outgoing radiation on specific halves of past and future null infinities, we show that ... More
Coordinated Broadcast-based Request-Reply and Group Management for Tightly-Coupled Wireless SystemsJun 27 2016As the domain of cyber-physical systems continues to grow, an increasing number of tightly-coupled distributed applications will be implemented on top of wireless networking technologies. Some of these applications, including collaborative robotic teams, ... More
The WebContent XML StoreJan 27 2010In this article, we describe the XML storage system used in the WebContent project. We begin by advocating the use of an XML database in order to store WebContent documents, and we present two different ways of storing and querying these documents : the ... More
Cosmological equivalence between the Finsler-Randers space-time and the DGP gravity modelJan 18 2013Jan 27 2013We perform a detailed comparison between the Finsler-Randers cosmological model and the Dvali, Gabadadze and Porrati braneworld model. If we assume that the spatial curvature is strictly equal to zero then we prove the following interesting proposition: ... More
Cosmological constrains from X-ray AGN clustering and SNIa dataMar 11 2005We put constraints on the main cosmological parameters of different spatially flat cosmological models by combining the recent clustering results of XMM-Newton soft (0.5-2 keV) X-ray sources, which have a redshift distribution with median redshift $z\sim ... More
The Richness-Shape Relation of the 2dFGRS GroupsFeb 26 2004We estimate the group shape of the recently compiled Pecolation-Inferred Galaxy Group (2PIGG) catalogue. Using a set of integral equations we invert the projected distribution of group axial ratios and recover the corresponding intrinsic distribution ... More
Integral Kahler Invariants and the Bergman kernel asymptotics for line bundlesJan 11 2015On a compact Kahler manifold, one can define global invariants by integrating local invariants of the metric. Assume that a global invariant thus obtained depends only on the Kahler class. Then we show that the integrand can be decomposed into a Chern ... More
On the profile of energy concentration at blow-up points for sub-conformal focusing nonlinear wavesDec 21 2014Apr 05 2017We consider singularities of the focusing subconformal nonlinear wave equation and some generalizations of it. At noncharacteristic points on the singularity surface, Merle and Zaag have identified the rate of blow-up of the $H^1$-norm of the solution ... More
Orbifold Duality Symmetries and Quantum Hall systemsJun 03 1998Nov 26 1998We consider the possible role that chiral orbifold conformal field theories may play in describing the edge state theories of quantum Hall systems. This is a generalization of work that already exists in the literature, where it has been shown that 1+1 ... More
Growth index of matter perturbations in running vacuum modelsSep 22 2015Nov 21 2015We derive for the first time the growth index of matter perturbations of the FLRW flat cosmological models in which the vacuum energy depends on redshift. A particularly well motivated model of this type is the so-called quantum field vacuum, in which ... More
In-situ evidence of electron energization in the electron diffusion region of magnetotail reconnectionFeb 26 2016Magnetic reconnection is an explosive energy-release process in laboratory, space and astrophysical plasmas. While magnetic fields can `break' and `reconnect' in a very small region called the electron diffusion region (EDR), there have been conflicting ... More
Supergravity and the jet quenching parameter in the presence of R-charge densitiesJun 20 2006Jan 01 2007Following a recent proposal, we employ the AdS/CFT correspondence to compute the jet quenching parameter for N=4 Yang-Mills theory at nonzero R-charge densities. Using as dual supergravity backgrounds non-extremal rotating branes, we find that the presence ... More
Angular distribution of cosmological parameters as a probe of inhomogeneities: a kinematic parametrisationMar 24 2016Jul 12 2016We use a kinematic parametrisation of the luminosity distance to measure the angular distribution on the sky of time derivatives of the scale factor, in particular the Hubble parameter H_0, the deceleration parameter q_0, and the jerk parameter j_0. We ... More
Growth index of matter perturbations in the light of Dark Energy SurveyMar 26 2019May 01 2019We study how the cosmological constraints from growth data are improved by including the measurements of bias from Dark Energy Survey (DES). In particular, we utilize the biasing properties of the DES Luminous Red Galaxies (LRGs) and the growth data provided ... More
Intense cross-tail field-aligned currents in the plasma sheet at lunar distancesNov 23 2017Field-aligned currents in the Earth's magnetotail are traditionally associated with transient plasma flows and strong plasma pressure gradients in the near-Earth side. In this paper we demonstrate a new field-aligned current system present at the lunar ... More
A systematic search for anomaly-free supergravities in six dimensionsAug 23 2005Sep 12 2005We conduct a systematic search for anomaly-free six-dimensional N=1 chiral supergravity theories. Under a certain set of restrictions on the allowed gauge groups and the representations of the hypermultiplets, we enumerate all possible Poincare and gauged ... More
On the scalar sector of the covariant graviton two-point function in de Sitter spacetimeNov 18 2000May 22 2001We examine the scalar sector of the covariant graviton two-point function in de Sitter spacetime. This sector consists of the pure-trace part and another part described by a scalar field. We show that it does not contribute to two-point functions of gauge-invariant ... More
A Priori Tests for the MIXMAX Random Number GeneratorApr 03 2018We define two a priori tests of pseudo-random number generators for the class of linear matrix-recursions. The first desirable property of a random number generator is the smallness of serial or lagged correlations between generated numbers. For the particular ... More
Gauged D=7 Supergravity on the S**1/Z_2 OrbifoldJul 26 2004Mar 01 2005We construct the most general couplings of a bulk seven-dimensional Yang-Mills-Einstein N=2 supergravity with a boundary six-dimensional chiral N=(0,1) theory of vectors and charged hypermultiplets. The boundary consists of two brane worlds sitting at ... More
The covariant graviton propagator in de Sitter spacetimeJul 10 2001Sep 09 2001We consider the covariant graviton propagator in de Sitter spacetime in a gauge with two parameters, alpha and beta, in the Euclidean approach. We give an explicit form of the propagator with a particular choice of beta but with arbitrary value of alpha. ... More
Theory of Pulsed Four-Wave-Mixing in One-dimensional Silicon Photonic Crystal Slab WaveguidesJul 15 2015We present a comprehensive theoretical analysis and computational study of four-wave mixing (FWM) of optical pulses co-propagating in one-dimensional silicon photonic crystal waveguides (Si-PhCWGs). Our theoretical analysis describes a very general set-up ... More
Hyperbolic Inflation in the Light of Planck 2015 dataApr 14 2015May 21 2015Rubano and Barrow have discussed the emergence of a dark energy, with late-time cosmic acceleration arising from a self-interacting homogeneous scalar field with a potential of hyperbolic power type. Here, we study the evolution of this scalar field potential ... More
Growth index of matter perturbations in the light of Dark Energy SurveyMar 26 2019We study how the cosmological constraints from growth data are improved by including the measurements of bias from Dark Energy Survey (DES). In particular, we utilize the biasing properties of the DES Luminous Red Galaxies (LRGs) and the growth data provided ... More