Results for "Michael Tovar"
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Wheeler-DeWitt quantization and singularitiesJan 17 2015We consider a Bohmian approach to the Wheeler-DeWitt quantization of the Friedmann-Lemaitre-Robertson-Walker model and investigate the question whether or not there are singularities, in the sense that the universe reaches zero volume. We find that for ... More Laue three dimensional neutron diffractionFeb 08 2019This article presents a measurement technique and data analysis tool to perform 3D grain distribution mapping and indexing of oligocrystalline samples using neutrons: Laue three-dimensional neutron diffraction (Laue3DND). The approach builds on forward ... More Brane world in Non-Riemannian GeometryDec 12 2012We carefully investigate the modified Einstein's field equation in a four dimensional (3-brane) arbitrary manifold embedded in a five dimensional Non-Riemannian bulk spacetime with a noncompact extra dimension. In this context the Israel-Darmois matching ... More Dzyaloshinskii-Moriya interactions in valence bond systemsSep 01 2008Oct 22 2008We investigate the effect of Dzyaloshinskii-Moriya interactions on the low temperature magnetic susceptibility for a system whose low energy physics is dominated by short-range valence bonds (singlets). Our general perturbative approach is applied to ... More Magnetic polarons in Ca_(1-x)Y_xMnO_3Aug 17 2001Experimental evidence show that in the magnetoresistive manganite Ca_(1-x) Y_xMnO_3, ferromagnetic (FM) polarons arises in an antiferromagnetic (AF) background, as a result of the doping with Yttrium. This hypothesis is supported in this work by classical ... More Full Optical Fiber Link Characterization with the BSS-LassoJun 08 2018Dec 29 2018Manipulation of the detected backscattered Rayleigh signal inside the bandwidth of a frequency-swept optical sub-carrier propagating into an optical fiber permits an efficient localization of faults through a Fourier operator. When the bandwidth is restricted, ... More Overcharging: The Crucial Role of Excluded VolumeNov 19 2001Aug 05 2002In this Letter we investigate the mechanism for overcharging of a single spherical colloid in the presence of aqueous salts within the framework of the primitive model by molecular dynamics (MD) simulations as well as integral-equation theory. We find ... More On Covert Acoustical Mesh Networks in AirJun 04 2014Covert channels can be used to circumvent system and network policies by establishing communications that have not been considered in the design of the computing system. We construct a covert channel between different computing systems that utilizes audio ... More Root Refinement for Real PolynomialsApr 07 2011Jun 12 2013We consider the problem of approximating all real roots of a square-free polynomial $f$. Given isolating intervals, our algorithm refines each of them to a width of $2^{-L}$ or less, that is, each of the roots is approximated to $L$ bits after the binary ... More Open Mobile API: Accessing the UICC on Android DevicesJan 12 2016This report gives an overview of secure element integration into Android devices. It focuses on the Open Mobile API as an open interface to access secure elements from Android applications. The overall architecture of the Open Mobile API is described ... More A natural probability measure derived from Stern's diatomic sequenceJun 01 2017Mar 15 2018Stern's diatomic sequence with its intrinsic repetition and refinement structure between consecutive powers of $2$ gives rise to a rather natural probability measure on the unit interval. We construct this measure and show that it is purely singular continuous, ... More An algorithm for quantifying dependence in multivariate data setsJul 04 2012Sep 27 2012We describe an algorithm to quantify dependence in a multivariate data set. The algorithm is able to identify any linear and non-linear dependence in the data set by performing a hypothesis test for two variables being independent. As a result we obtain ... More Slow Steady-Shear of Plastic Bead RaftsOct 12 2004Experimental measurements of the response of a two dimensional system of plastic beads subjected to steady shear are reported. The beads float at the surface of a fluid substrate and are subjected to a slow, steady-shear in a Couette geometry. The flow ... More Asymmetric response of a jammed plastic bead raftMay 18 2006Fluctuation-dissipation relations have received significant attention as a potential method for defining an effective temperature in nonequilibrium systems. The successful development of an effective temperature would be an important step in the application ... More A Worst-case Bound for Topology Computation of Algebraic CurvesApr 08 2011Computing the topology of an algebraic plane curve $\mathcal{C}$ means to compute a combinatorial graph that is isotopic to $\mathcal{C}$ and thus represents its topology in $\mathbb{R}^2$. We prove that, for a polynomial of degree $n$ with coefficients ... More The periodic Floer homology of a Dehn twistOct 04 2004May 02 2005The periodic Floer homology of a surface symplectomorphism, defined by the first author and M. Thaddeus, is the homology of a chain complex which is generated by certain unions of periodic orbits, and whose differential counts certain embedded pseudoholomorphic ... More A Variant of K-theory: K_{+-}Feb 11 2003We describe a variant of K-theory for spaces with involution, built from vector bundles which are sent to their negative under the involution. Evaluation of Contactless Smartcard AntennasJul 23 2015This report summarizes the results of our evaluation of antennas of contactless and dual interface smartcards and our ideas for user-switchable NFC antennas. We show how to disassemble smartcards with contactless capabilities in order to obtain the bare ... More CPT and Other Symmetries in String/M TheorySep 20 2004Feb 05 2005We initiate a search for non-perturbative consistency conditions in M theory. Some non-perturbative conditions are already known in Type I theories; we review these and search for others. We focus principally on possible anomalies in discrete symmetries. ... More Linear programming methods for exponential dominationJan 19 2018For a graph $G,$ we consider $D \subset V(G)$ to be a porous exponential dominating set if $1 \le \sum_{d \in D}$ $\left( \tfrac{1}{2} \right)^{dist(d,v) -1}$ for every $v \in V(G),$ where $dist(d,v)$ denotes the length of the shortest $dv$ path. The ... More On exponential domination of the consecutive circulant graphDec 14 2017For a graph $G,$ we consider $D \subset V(G)$ to be a porous exponential dominating set if $1\le \sum_{d \in D}$ $\left( \frac{1}{2} \right)^{\text{dist}(d,v) -1}$ for every $v \in V(G),$ where dist$(d,v)$ denotes the length of the smallest $dv$ path. ... More R-M interactions in R2BaMO5 (R=Y or Gd and M=Cu or Zn)Feb 26 2013R2BaMO5 (R = Gd, Y and M = Cu, Zn) oxides have been studied by specific heat, dc magnetic susceptibility, and electron paramagnetic resonance (EPR). For one member of the series without magnetic moment at M, namely Gd2BaZnO5, measurements reveal long ... More C- and O-Rich Miras and Galactic StructureSep 12 2006This paper summarizes the conclusions of an extensive investigation of variable carbon AGB stars in our Galaxy. The zero-point of the period-M(bol) relation for Galactic C-Miras is found to be close to that in the LMC. The mean age of Galactic C-Miras ... More Cepheids as Distance Indicators: Some Current ProblemsOct 16 2001A general review is given of the calibration of the Cepheid distance scale, with particular reference to its use in the determination of H0. Emphasis is placed on the advantage of using a galactic calibration of the Cepheid scale, rather than relying ... More A Short and Personal History of the Spitzer Space TelescopeMar 29 2005The Spitzer Space Telescope, born as the Shuttle Infrared Telescope Facility (SIRTF) and later the Space Infrared Telescope Facility (still SIRTF), was under discussion and development within NASA and the scientific community for more than 30 years prior ... More On the discrete spectrum of a family of differential operatorsMar 14 2004A family $\BA_\a$ of differential operators depending on a real parameter $\a$ is considered. The problem can be formulated in the language of perturbation theory of quadratic forms. The perturbation is only relatively bounded but not relatively compact ... More Compactifications of Semigroups and Semigroup ActionsNov 25 2006Dec 10 2006An action of a topological semigroup S on X is compactifiable if this action is a restriction of a jointly continuous action of S on a Hausdorff compact space Y. A topological semigroup S is compactifiable if the left action of S on itself is compactifiable. ... More Discontinuous Jamming Transitions in Soft MaterialsJan 16 2008Many systems in nature exhibit transitions between fluid-like states and solid-like states, or "jamming transitions". There is a strong theoretical foundation for understanding equilibrium phase transitions that involve solidification, or jamming. Other ... More A note on the vanishing of certain local cohomology modulesMar 30 2012For a finite module $M$ over a local, equicharacteristic ring $(R,m)$, we show that the well-known formula $\cohdim(m,M)=\dim M$ becomes trivial if ones uses Matlis duals of local cohomology modules together with spectral sequences. We also prove a new, ... More A Method of Rotations for Lévy MultipliersAug 13 2015Aug 14 2015We use a method of rotations to study the $L^p$ boundedness, $1<p<\infty$, of Fourier multipliers which arise as the projection of martingale transforms with respect to symmetric $\alpha$-stable processes, $0<\alpha<2$. Our proof does not use the fact ... More Concordance of $Z_p\times\Z_p$ actions on $S^4$Nov 08 2005We consider locally linear Z_p x Z_p actions on the four-sphere. We present simple constructions of interesting examples, and then prove that a given action is concordant to its linear model if and only if a single surgery obstruction taking to form of ... More q-Levy processesSep 08 2003Jan 21 2004We continue the investigation of the Levy processes on a q-deformed full Fock space started in a previous paper. First, we show that the vacuum vector is cyclic and separating for the algebra generated by such a process. Next, we describe a chaotic representation ... More Free martingale polynomialsDec 19 2001In this paper we investigate the properties of the free Sheffer systems, which are certain families of martingale polynomials with respect to the free Levy processes. First, we classify such families that consist of orthogonal polynomials; these are the ... More Free stochastic measures via noncrossing partitions IIFeb 07 2001Oct 23 2001We show that for stochastic measures with freely independent increments, the partition-dependent stochastic measures of math.OA/9903084 can be expressed purely in terms of the higher stochastic measures and the higher diagonal measures of the original. ... More Generators of some non-commutative stochastic processesApr 07 2011Jan 22 2013A fundamental result of Biane (1998) states that a process with freely independent increments has the Markov property, but that there are two kinds of free Levy processes: the first kind has stationary increments, while the second kind has stationary ... More Appell polynomials and their relatives II. Boolean theoryDec 27 2007The Appell-type polynomial family corresponding to the simplest non-commutative derivative operator turns out to be connected with the Boolean probability theory, the simplest of the three universal non-commutative probability theories (the other two ... More Quark masses, the Dashen phase, and gauge field topologyJun 05 2013Oct 17 2013The CP violating Dashen phase in QCD is predicted by chiral perturbation theory to occur when the up-down quark mass difference becomes sufficiently large at fixed down-quark mass. Before reaching this phase, all physical hadronic masses and scattering ... More Anomalies and discrete chiral symmetriesSep 28 2009Oct 06 2009The quantum anomaly that breaks the U(1) axial symmetry of massless multi-flavored QCD leaves behind a discrete flavor-singlet chiral invariance. With massive quarks, this residual symmetry has a close connection with the strong CP-violating parameter ... More Hidden symmetries in two dimensional field theoryAug 16 2005Jan 31 2006The bosonization process elegantly shows the equivalence of massless scalar and fermion fields in two space-time dimensions. However, with multiple fermions the technique often obscures global symmetries. Witten's non-Abelian bosonization makes these ... More Isospin breaking and the chiral condensateAug 13 2005With two degenerate quarks, the chiral condensate exhibits a jump as the quark masses pass through zero. I discuss how this single transition splits into two Ising like transitions when the quarks are made non-degenerate. The order parameter is the expectation ... More Transiting topological sectors with the overlapAug 16 2002The overlap operator provides an elegant definition for the winding number of lattice gauge field configurations. Only for a set of configurations of measure zero is this procedure undefined. Without restrictions on the lattice fields, however, the space ... More Lattice gauge theory: A retrospectiveOct 26 2000I discuss some of the historical circumstances that drove us to use the lattice as a non-perturbative regulator. This approach has had immense success, convincingly demonstrating quark confinement and obtaining crucial properties of the strong interactions ... More Quark mass dependence of two-flavor QCDOct 21 2010Dec 17 2010I explore the rich phase diagram of two-flavor QCD as a function of the quark masses. The theory involves three parameters, including one that is CP violating. As the masses vary, regions of both first and second order transitions are expected. For non-degenerate ... More The saga of rooted staggered quarksApr 28 2008Apr 30 2008I look at the rooting controversy from a historical point of view and review how I have come to the conclusion that these simulations involving staggered quarks must be discarded. Aspects of Chiral Symmetry and the LatticeJul 21 2000Oct 03 2000I explore the non-perturbative issues entwining lattice gauge theory, anomalies, and chiral symmetry. After briefly reviewing the importance of chiral symmetry in particle physics, I discuss how anomalies complicate lattice formulations. Considerable ... More Evaluating Grassmann IntegralsJun 30 1998Sep 11 1998I discuss a simple numerical algorithm for the direct evaluation of multiple Grassmann integrals. The approach is exact, suffers no Fermion sign problems, and allows arbitrarily complicated interactions. Memory requirements grow exponentially with the ... More Quark masses, chiral symmetry, and the U(1) anomalyAug 02 1996I discuss the mass parameters appearing in the gauge theory of the strong interactions, concentrating on the two flavor case. I show how the effect of the CP violating parameter $\theta$ is simply interpreted in terms of the state of the {\ae}ther via ... More Chiral symmetry and lattice gauge theoryOct 19 1994I review the problem of formulating chiral symmetry in lattice gauge theory. I discuss recent approaches involving an infinite tower of additional heavy states to absorb Fermion doublers. For hadronic physics this provides a natural scheme for taking ... More Braid Monodromy of Hypersurface SingularitiesFeb 17 2006We introduce braid monodromy for the discriminant hypersurface in versal unfoldings of hypersurface singularities. Our objective is then to compute this invariant for singularities of Brieskorn Pham type: First we consider the unfolding by linear monomials ... More Cosmic Rays above the KneeDec 15 2008An overview on the present observational status and phenomenological understanding of cosmic rays above 10^16 eV is given. Above these energies the cosmic ray flux is expected to be gradually dominated by an extra-galactic component. In order to investigate ... More Supersymmetry Breaking at Low EnergiesJan 13 2009These lectures, given at the Cargese Summer school in 2008, provide an introduction to dynamical supersymmetry breaking and gauge mediation, with emphasis on the recent appreciation of the possible role of metastable supersymmetry breaking, and the evolving ... More Supersymmetry Phenomenology With a Broad BrushDec 17 1996These lectures provide an introduction to supersymmetry phenomenology. They include an overview of the Minimal Supersymmetric Standard Model. The notion of soft breaking is explained, constraints on the standard soft breaking parameters are reviewed, ... More String Theory: Lessons for Low Energy PhysicsOct 08 1992Oct 16 1992This talk considers possible lessons of string theory for low energy physics. These are of two types. First, assuming that string theory is the correct underlying theory of all interactions, we ask whether there are any generic predictions the theory ... More Some Reflections on Moduli, Their Stabilization and CosmologyJan 24 2000Feb 07 2000We review some aspects of moduli in string theory. We argue that one should focus on {\it approximate moduli spaces}, and that there is evidence that such spaces exist non-perturbatively. We ask what it would mean for string theory to predict low energy ... More Seeking the Ground State of String TheoryMar 25 1999Mar 26 1999Recently, a number of authors have challenged the conventional assumption that the string scale, Planck mass, and unification scale are roughly comparable. It has been suggested that the string scale could be as low as a TeV. The greatest obstacle to ... More String Theory DualitiesSep 06 1996The past year has seen enormous progress in string theory. It has become clear that all of the different string theories are different limits of a single theory. Moreover, in certain limits, one obtains a new, eleven-dimensional structure known as $M$-theory. ... More Topics in String PhenomenologySep 23 1993We consider two questions in string ``phenomenology.'' First, are there any generic string predictions? Second, are there any general lessons which string theory suggests for thinking about low energy models, particularly in the framework of supersymmetry? ... More Problems of Naturalness: Some Lessons from String TheoryJul 14 1992Jul 17 1992We consider some questions of naturalness which arise when one considers conventional field theories in the presence of gravitation: the problem of global symmetries, the strong CP problem, and the cosmological constant problem. Using string theory as ... More Extrinsic Magnetotransport Phenomena in Ferromagnetic OxidesNov 14 2001This review is focused on extrinsic magnetotransport effects in ferromagnetic oxides. It consists of two parts; the second part is devoted to an overview of experimental data and theoretical models for extrinsic magnetotransport phenomena. Here a critical ... More Has wild poliovirus been eliminated from Nigeria?Apr 10 2015Jul 10 2015Wild poliovirus type 3 (WPV3) has not been seen anywhere since the last case of WPV3-associated paralysis in Nigeria in November 2012. At the time of writing, the most recent case of wild poliovirus type 1 (WPV1) in Nigeria occurred in July 2014, and ... More Millisecond Pulsars as Tools of Fundamental PhysicsMay 10 2004May 11 2004A new era in fundamental physics began when pulsars were discovered in 1967. Soon it became clear that pulsars were useful tools for a wide variety of physical and astrophysical problems. Further applications became possible with the discovery of the ... More Quarkonium Production at High-Energy CollidersJun 12 2001The theoretical description of heavy quarkonium production at high-energy p-pbar and e-p colliders is reviewed. Predictions based on non-relativistic QCD factorisation are confronted with recent charmonium and bottomonium data from the Tevatron and HERA. ... More QCD Corrections to Inelastic $J/ψ$ PhotoproductionAug 31 1995We present a complete calculation of the higher-order perturbative QCD corrections to inelastic photoproduction of $J/\psi$ particles. A comprehensive analysis of total cross sections and differential distributions for the energy range of the fixed-target ... More Inclusive $J/ψ$ photoproduction at HERAJul 24 1997I discuss the impact of color-octet contributions to inclusive $J/\psi$ photoproduction at HERA. Emphasis is put on resolved photon processes and on $J/\psi$ polarization, which will be experimentally accessible at HERA in the near future. Both analyses ... More Parsing Using Linearly Ordered Phonological RulesNov 08 1994Nov 09 1994A generate and test algorithm is described which parses a surface form into one or more lexical entries using linearly ordered phonological rules. This algorithm avoids the exponential expansion of search space which a naive parsing algorithm would face ... More Near equality in the two-dimensional Brunn-Minkowski inequalityJun 09 2012Jul 20 2012If a pair of subsets of two-dimensional Euclidean space nearly achieves equality in the Brunn-Minkowski inequality, in the sense that the measure of the associated sumset is nearly equal to the lower bound provided by the inequality, then these sets must ... More Ricci Curvature and the Mechanics of SolidsMay 12 2010We discuss some differential geometry pertaining to continuum mechanics and the route recently taken by D.N. Arnold, R.S. Falk, and R. Winther in deriving new improved finite element schemes in linear elasticity from constructions in projective geometry. ... More Hubs and Authorities of the English Premier League for 2010-2011Apr 01 2013In this work author applies well known web search algorithm Hyperlink - Induced Topic Search (HITS) to problem of ranking football teams in English Premier League (EPL). The algorithm allows the ranking of the teams using the notions of hubs and authorities ... More Quantum Cellular Automata from Lattice Field TheoriesJul 24 2003We apply the methods of lattice field theories to the quantization of cellular automata. We discuss the quantization of five main categories of cellular automata: bosonic, fermionic, supersymmetric, spin and quantum dot using path integral and operator ... More