Results for "David A. Ruiz-Tijerina"

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Capacitive interactions and Kondo effect tuning in double quantum impurity systemsApr 15 2014We present a study of the correlated transport regimes of a double quantum impurity system with mutual capacitive interactions. Such system can be implemented by a double quantum dot arrangement or by a quantum dot and nearby quantum point contact, with ... More
Resonantly enhanced moiré superlattice coupling in heterostructures and transition-metal dichalcogenide bilayers with matching band edgesSep 24 2018Geometrical moir\'e patterns, generic for almost aligned bilayers of two-dimensional (2D) crystals with similar lattice structure but slightly different lattice constants, lead to zone folding and miniband formation for electronic states. Here, we show ... More
Interaction effects on a Majorana zero mode leaking into a quantum dotDec 04 2014Apr 02 2015We have recently shown [Phys. Rev. B {\bf 89}, 165314 (2014)] that a non--interacting quantum dot coupled to a one--dimensional topological superconductor and to normal leads can sustain a Majorana mode even when the dot is expected to be empty, \emph{i.e.}, ... More
Symmetry-protected coherent transport for diluted vacancies and adatoms in grapheneJun 02 2016Aug 30 2016We study the effects of a low concentration of adatoms or single vacancies in the linear-response transport properties of otherwise clean graphene. These impurities were treated as localized orbitals, and for each type two cases with distinct coupling ... More
Dynamical magnetic anisotropy and quantum phase transitions in a vibrating spin-1 molecular junctionApr 05 2012Jul 29 2012We study the electronic transport through a spin-1 molecule in which mechanical stretching produces a magnetic anisotropy. In this type of device, a vibron mode along the stretching axis will couple naturally to the molecular spin. We consider a single ... More
Transport signatures of Kondo physics and quantum criticality in graphene with magnetic impuritiesDec 15 2016Mar 06 2017Localized magnetic moments have been predicted to develop in graphene samples with vacancies or adsorbates. The interplay between such magnetic impurities and graphene's Dirac quasiparticles leads to remarkable many-body phenomena, which have so far proved ... More
Hybrid k$\cdot$p tight-binding model for subbands and infrared intersubband optics in few-layer films of transition-metal dichalcogenides: MoS$_2$, MoSe$_2$, WS$_2$ and WSe${}_2$Aug 04 2018We present a density functional theory parametrized hybrid k$\cdot$p tight binding model for electronic properties of atomically thin films of transition-metal dichalcogenides, 2H-$MX_2$ ($M$=Mo, W; $X$=S, Se). We use this model to analyze intersubband ... More
Localized interlayer complexes in heterobilayer transition metal dichalcogenidesFeb 16 2018Jun 01 2018We present theoretical results for the radiative rates and doping-dependent photoluminescence spectrum of interlayer excitonic complexes localized by donor impurities in MoSe$_2$/WSe$_2$ twisted heterobilayers, supported by quantum Monte Carlo calculations ... More
Nano-imaging of intersubband transitions in van der Waals quantum wellsJun 25 2018The science and applications of electronics and optoelectronics have been driven for decades by progress in growth of semiconducting heterostructures. Many applications in the infrared and terahertz frequency range exploit transitions between quantized ... More
Resonantly hybridised excitons in moiré superlattices in van der Waals heterostructuresApr 12 2019Atomically-thin layers of two-dimensional materials can be assembled in vertical stacks held together by relatively weak van der Waals forces, allowing for coupling between monolayer crystals with incommensurate lattices and arbitrary mutual rotation. ... More
A note on the uniformity of the constant in the Poincaré inequalityAug 29 2012The classical Poincar\'e inequality establishes that for any bounded regular domain $\Omega\subset \R^N$ there exists a constant $C=C(\Omega)>0$ such that $$ \int_{\Omega} |u|^2\, dx \leq C \int_{\Omega} |\nabla u|^2\, dx \ \ \forall u \in H^1(\Omega),\ ... More
On the Schrodinger-Poisson-Slater system: behavior of minimizers, radial and nonradial casesApr 19 2009This paper is motivated by the study of a version of the so-called Schrodinger-Poisson-Slater problem: $$ - \Delta u + \omega u + \lambda (u^2 \star \frac{1}{|x|}) u=|u|^{p-2}u,$$ where $u \in H^1(\R^3)$. We are concerned mostly with $p \in (2,3)$. The ... More
New improved Moser-Trudinger inequalities and singular Liouville equations on compact surfacesJul 22 2010May 18 2011We consider a singular Liouville equation on a compact surface, arising from the study of Chern-Simons vortices in a self dual regime. Using new improved versions of the Moser-Trudinger inequalities (whose main feature is to be scaling invariant) and ... More
Boundary concentration of a Gauged Nonlinear Schrodinger EquationJul 30 2013This paper is motivated by a gauged Schrodinger equation in dimension 2 including the so-called Chern-Simons term. The radially symmetric case leads to an elliptic problem with a nonlocal defocusing term, in competition with a local focusing nonlinearity. ... More
The initial boundary value problem for free-evolution formulations of General RelativitySep 22 2016We consider the initial boundary value problem for free-evolution formulations of general relativity coupled to a parametrized family of coordinate conditions that includes both the moving puncture and harmonic gauges. We concentrate primarily on boundaries ... More
Ground and bound states for a static Schrodinger-Poisson-Slater problemApr 27 2009May 15 2009In this paper the following version of the Schrodinger-Poisson-Slater problem is studied: $$ - \Delta u + (u^2 \star \frac{1}{|4\pi x|}) u=\mu |u|^{p-1}u, $$ where $u: \R^3 \to \R$ and $\mu>0$. The case $p <2$ being already studied, we consider here $p ... More
Cluster solutions for the Schrodinger-Poisson-Slater problem around a local minimum of the potentialApr 27 2009In this paper we consider the system in $\R^3$ \label{problemadipartenza0} -\e^2\Delta u+V(x)u+\phi(x)u=u^{p},
Existence of ground states for a modified nonlinear Schrodinger equationOct 30 2009In this paper we prove existence of ground state solutions of the modified nonlinear Schrodinger equation: $$ -\Delta u+V(x)u-{1/2}u \Delta u^{2}=|u|^{p-1}u, x \in \R^N, N \geq 3, $$ under some hypotheses on $V(x)$. This model has been proposed in the ... More
On the Leray-Schauder degree of the Toda system on compact surfacesNov 28 2013In this paper we consider the so-called Toda system of equations on a compact surface. In particular, we discuss the parity of the Leray-Schauder degree of that problem. Our main tool is a theorem of Krasnoselskii and Zabreiko on the degree of maps symmetric ... More
A variational Analysis of the Toda System on Compact SurfacesMay 18 2011Nov 23 2011In this paper we consider the Toda system of equations on a compact surface. We will give existence results by using variational methods in a non coercive case. A key tool in our analysis is a new Moser-Trudinger type inequality under suitable conditions ... More
The initial boundary value problem for free-evolution formulations of General RelativitySep 22 2016Jan 02 2018We consider the initial boundary value problem for free-evolution formulations of general relativity coupled to a parametrized family of coordinate conditions that includes both the moving puncture and harmonic gauges. We concentrate primarily on boundaries ... More
A Variational Analysis of a Gauged Nonlinear Schrödinger EquationJun 09 2013This paper is motivated by a gauged Schr\"odinger equation in dimension 2 including the so-called Chern-Simons term. The study of radial stationary states leads to the nonlocal problem: $$ - \Delta u(x) + \left(\omega + \frac{h^2(|x|)}{|x|^2} + \int_{|x|}^{+\infty} ... More
Typing Supernova Remnants Using X-ray Line Emission MorphologiesOct 19 2009We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring the morphology of the Chandra X-ray line emission in seventeen Galactic and Large Magellanic Cloud SNRs with a multipole expansion analysis (using ... More
Tools for Dissecting Supernova Remnants Observed with Chandra: Methods and Application to the Galactic Remnant W49BSep 30 2008Oct 02 2008We introduce methods to quantify the X-ray morphologies of supernova remnants observed with the Chandra X-ray Telescope. These include a power-ratio technique to measure morphological asymmetries, correlation-length analysis to probe chemical segregation ... More
Using the X-ray Morphologies of Young Supernova Remnants to Constrain Explosion Type, Ejecta Distribution, and Chemical MixingNov 02 2010Supernova remnants (SNRs) are a complex class of sources, and their heterogeneous nature has hindered the characterization of their general observational properties. To overcome this challenge, we use statistical tools to analyze the Chandra X-ray images ... More
Domain Walls in a FRW UniverseJan 26 1995Nov 14 1995We solve the equations of motion for a scalar field with domain wall boundary conditions in a Friedmann-Robertson-Walker (FRW) spacetime. We find (in agreement with Basu and Vilenkin) that no domain wall solutions exist in de Sitter spacetime for h = ... More
Strongly Non-Arrhenius Self-Interstitial Diffusion in VanadiumJan 26 2004We study diffusion of self-interstitial atoms (SIAs) in vanadium via molecular dynamics simulations. The <111>-split interstitials are observed to diffuse one-dimensionally at low temperature, but rotate into other <111> directions as the temperature ... More
Discovery of a red ultra-diffuse galaxy in a nearby void based on its globular cluster luminosity functionMar 19 2019Distance determinations of extremely-low-surface-brightness galaxies are expensive in terms of spectroscopic time. Because of this, their distances are often inferred by associating such galaxies with larger structures such as groups or clusters, leading ... More
Odd symmetry of least energy nodal solutions for the Choquard equationJun 17 2016We consider the Choquard equation (also known as stationary Hartree equation or Schr\"odinger--Newton equation) \[ -\Delta u + u = (I_\alpha \star |u|^p) |u|^{p - 2}u. \] Here $I_\alpha$ stands for the Riesz potential of order $\alpha \in (0,N)$, and ... More
Prescribing the Gaussian curvature in a subdomain of S^2 with Neumann boundary conditionFeb 10 2014May 20 2014In this paper we study the problem of prescribing the Gaussian curvature under a conformal change of the metric. We are concerned with the problem posed on a subdomain of the 2-sphere under Neumann boundary conditions of the conformal factor. If the area ... More
Positive and sign-changing clusters around saddle points of the potential for nonlinear elliptic problemsJul 03 2009We study the existence of positive and sign-changing multipeak solutions for the stationary Nonlinear Schroedinger Equation. Here no symmetry on $V$ is assumed. It is known that this equation has positive multipeak solutions with all peaks approaching ... More
Rejection Sampling Variational InferenceOct 18 2016Variational inference using the reparameterization trick has enabled large-scale approximate Bayesian inference in complex probabilistic models, leveraging stochastic optimization to sidestep intractable expectations. The reparameterization trick is applicable ... More
A simplified categorical approach to several Galois theoriesMay 28 2018We discuss the concept of Galois structure and Galois epimorphism in a general setting. Namely, a Galois structure for an epimorphism $\pi\colon M\to B$ in some category ${\bf Cat}$ is the action of a group object that gives to $M$ the structure of principal ... More
Constraints on a Putative Planet Sculpting the V4046 Sagittarii Circumbinary DiskApr 18 2019We analyze the highest-resolution millimeter continuum and near-infrared (NIR) scattered-light images presented to date of the circumbinary disk orbiting V4046 Sgr, a ~20 Myr old actively accreting, close binary T Tauri star system located a mere 72.4 ... More
Magnetoelectric effect in cylindrical topological insulatorsAug 29 2018Topological insulators (TIs) exhibit a quantized magnetoelectric response when time-reversal symmetry is broken on its surface. This unusual electromagnetic (EM) response is a unique macroscopic manifestation of the quantum Hall effect on the TI surface ... More
Iron K-alpha Emission from X-ray Reflection: Predictions for Gamma-Ray Burst ModelsAug 20 2001Recent observations of several gamma-ray burst (GRB) afterglows have shown evidence for a large amount of X-ray line emitting material, possibly arising from ionized iron. A significant detection of an X-ray spectral feature, such as that found in the ... More
Standing waves for a gauged nonlinear Schrödinger equation with a vortex pointFeb 20 2015This paper is motivated by a gauged Schr\"{o}dinger equation in dimension 2. We are concerned with radial stationary states under the presence of a vortex at the origin. Those states solve a nonlinear nonlocal PDE with a variational structure. We will ... More
Solutions to overdetermined elliptic problems in nontrivial exterior domainsSep 13 2016In this paper we construct nontrivial exterior domains $\Omega \subset \mathbb{R}^N$, for all $N\geq 2$, such that the problem $$\left\{ {ll} -\Delta u +u -u^p=0,\ u >0 & \mbox{in }\; \Omega, {1mm] \ u= 0 & \mbox{on }\; \partial \Omega, [1mm] \ \frac{\partial ... More
Local and Global Aspects of Lie's Superposition TheoremJan 28 2009Nov 06 2009In this paper we give the global conditions for an ordinary differential equation to admit a superposition law of solutions in the classical sense. This completes the well-known Lie superposition theorem. We introduce rigorous notions of pretransitive ... More
Constraint preserving boundary conditions for the Z4c formulation of general relativityOct 04 2010Feb 09 2011We discuss high order absorbing constraint preserving boundary conditions for the Z4c formulation of general relativity coupled to the moving puncture family of gauges. We are primarily concerned with the constraint preservation and absorption properties ... More
Understanding Nanopore Window Distortions in the Reversible Molecular Valve Zeolite RHOMay 20 2016Molecular valves are becoming popular for potential biomedical applications. However, little is known concerning their performance in energy and environmental areas. Zeolite RHO shows unique pore deformations upon changes in hydration, cation siting, ... More
A rigidity result for overdetermined elliptic problems in the planeMay 21 2015Let $f:[0,+\infty) \to \mathbb{R}$ be a (locally) Lipschitz function and $\Omega \subset \mathbb{R}^2$ a $C^{1,\alpha}$ domain whose boundary is unbounded and connected. If there exists a positive bounded solution to the overdetermined elliptic problem ... More
A continuum of solutions for the SU(3) Toda System exhibiting partial blow-upJul 31 2014In this paper we consider the so-called Toda System in planar domains under Dirichlet boundary condition. We show the existence of continua of solutions for which one component is blowing up at a certain number of points. The proofs use singular perturbation ... More
Asymmetric blow-up for the SU(3) Toda SystemNov 13 2014We consider the so-called Toda system in a smooth planar domain under homogeneous Dirichlet boundary conditions. We prove the existence of a continuum of solutions for which both components blow-up at the same point. This blow-up behavior is asymmetric, ... More
Differential Galois Theory of Algebraic Lie-Vessiot SystemsJan 28 2009In this paper we develop a differential Galois theory for algebraic Lie-Vessiot systems in algebraic homogeneous spaces. Lie-Vessiot systems are non autonomous vector fields that are linear combinations with time-dependent coefficients of fundamental ... More
Conformal metrics with prescribed Gaussian and geodesic curvaturesJun 29 2018Jan 27 2019We consider the problem of prescribing the Gaussian and the geodesic curvatures of a compact surface with boundary by a conformal deformation of the metric. We derive some existence results using a variational approach, either by minimization of the Euler-Lagrange ... More
Controlling Thermal Expansion: a Metal Organic Frameworks RouteOct 25 2016Controlling thermal expansion is an important, not yet resolved, and challenging problem in materials research. A conceptual design is introduced here for the first time, for the use of MOFs as platforms for controlling thermal expansion devices that ... More
Nature of the Nodal Kink in Angle-Resolved Photoemission Spectra of Cuprate SuperconductorsNov 24 2008Feb 13 2009The experimental finding of an ubiquitous kink in the nodal direction of angle-resolved photoemission spectroscopies of superconducting cuprates has been reproduced theoretically. Our model is built upon the Migdal-Eliashberg theory for the electron self-energy ... More
Numerical Simulations of the Random Phase Sine Gordon ModelJul 31 1995Aug 01 1995We have performed comprehensive numerical simulations of the Random Phase Sine Gordon Model, studying both statics and dynamics for various values of the coupling. The glass transition can be seen both in static and dynamic signals at a temperature that ... More
Lie's Reduction Method and Differential Galois Theory in the Complex Analytic ContextJan 28 2009This paper is dedicated to the differential Galois theory in the complex analytic context for Lie-Vessiot systems. Those are the natural generaliza- tion of linear systems, and the more general class of differential equations adimitting superposition ... More
Semi-classical states for the Nonlinear Schrödinger Equation on saddle points of the potential via variational methodsJul 28 2011Mar 09 2012In this paper we study semiclassical states for the problem $$ -\eps^2 \Delta u + V(x) u = f(u) \qquad \hbox{in} \RN,$$ where $f(u)$ is a superlinear nonlinear term. Under our hypotheses on $f$ a Lyapunov-Schmidt reduction is not possible. We use variational ... More
Existence and uniqueness to several kinds of differential equations using the Coincidence TheoryMar 19 2014Mar 20 2014The purpose of this article is to study the existence of a coincidence point for two mappings defined on a nonempty set and taking values on a Banach space using the fixed point theory for nonexpansive mappings. Moreover, this type of results will be ... More
Free Fermionic Elliptic Reflection Matrices and Quantum Group InvarianceApr 23 1993Elliptic diagonal solutions for the reflection matrices associated to the elliptic $R$ matrix of the eight vertex free fermion model are presented. They lead through the second derivative of the open chain transfer matrix to an XY hamiltonian in a magnetic ... More
The Kovacs effect in the one-dimensional Ising model: a linear response analysisJan 19 2014We analyze the so-called Kovacs effect in the one-dimensional Ising model with Glauber dynamics. We consider small enough temperature jumps, for which a linear response theory has been recently derived. Within this theory, the Kovacs hump is directly ... More
Frames of subspaces and operatorsJun 11 2007Jun 15 2007We study the relationship between operators, orthonormal basis of subspaces and frames of subspaces (also called fusion frames) for a separable Hilbert space $\mathcal{H}$. We get sufficient conditions on an orthonormal basis of subspaces $\mathcal{E} ... More
Dormant dwarf spheroidal galaxies, deactivated by Type Ia supernovaeMar 17 1996Some dwarf spheroidal galaxies have experienced many Gyrs long periods without star formation. We show that Type Ia supernovae, formed from a first generation of stars, can delay a second epoch of star formation by several Gyrs, if the total gas mass ... More
An approximate global solution to the gravitational field of a perfect fluid in slow rotationNov 20 2006Using the Post-Minkowskian formalism and considering rotation as a perturbation, we compute an approximate interior solution for a stationary perfect fluid with constant density and axial symmetry. A suitable change of coordinates allows this metric to ... More
Chromospheric Activities and Kinematics for Solar Type Dwarfs and Subgiants: Analysis of the Activity Distribution and the AVRMar 03 2011In this work we present chromospheric activity indices, kinematics, radial-velocities and rotational velocities for more than 850 FGK-type dwarfs and subgiant stars in the southern hemisphere and test how best to calibrate and measure S-indices from echelle ... More
Two charges on plane in a magnetic field: II. Moving neutral quantum system across a magnetic fieldApr 13 2014Jul 10 2014The moving neutral system of two Coulomb charges on a plane subject to a constant magnetic field $B$ perpendicular to the plane is considered. It is shown that the composite system of finite total mass is bound for any center-of-mass momentum $P$ and ... More
Testing Lorentz- and CPT-invariance with ultracold neutronsMay 10 2018In this paper we investigate, within the standard model extension framework, the influence of Lorentz- and CPT-violating terms on gravitational quantum states of ultracold neutrons. Using a semiclassical wave packet, we derive the effective nonrelativistic ... More
Three charges on a plane in a magnetic field: Special trajectoriesMar 14 2018Mar 26 2018As a generalization and extension of JMP 54 (2013) 022901, the classical dynamics of three non-relativistic Coulomb charges $(e_1, m_1)$, $(e_2, m_2)$ and $(e_3, m_3)$ on the plane placed in a constant magnetic field perpendicular to the plane is considered. ... More
Two charges on a plane in a magnetic field: hidden algebra, (particular) integrability, polynomial eigenfunctionsMar 10 2013The quantum mechanics of two Coulomb charges on a plane $(e_1, m_1)$ and $(e_2, m_2)$ subject to a constant magnetic field $B$ perpendicular to the plane is considered. Four integrals of motion are explicitly indicated. It is shown that for two physically-important ... More
Two charges on plane in a magnetic field I. "Quasi-equal" charges and neutral quantum system at rest casesOct 09 2013Low-lying bound states for the problem of two Coulomb charges of finite masses on a plane subject to a constant magnetic field $B$ perpendicular to the plane are considered. Major emphasis is given to two systems: two charges with the equal charge-to-mass ... More
A Theoretical Model for Mars Crater-Size Frequency DistributionFeb 02 2004We present a theoretical and analytical curve with reproduce essential features of the frequency distributions vs. diameter, of the 42,000 crater contained in the Barlow Mars Catalog. The model is derived using reasonable simple assumptions that allow ... More
On the equivalence between bumblebee models and electrodynamics in a non-linear gaugeMar 03 2017Bumblebee models are effective field theories describing a vector field with a nonzero vacuum expectation value that spontaneously breaks Lorentz invariance. They provide an alternative way of exploring the similarities between theories with spontaneous ... More
Casimir effect between ponderable media as modeled by the standard model extensionAug 10 2016The CPT-even sector of the standard model extension amounts to extending Maxwell electrodynamics by a gauge invariant term of the form $- \frac{1}{4} (k _{F}) _{\alpha \beta \mu \nu} F ^{\alpha \beta} F ^{\mu \nu}$, where the Lorentz-violating (LV) background ... More
Gravitational Searches for Lorentz Violation with Ultracold NeutronsFeb 18 2019We investigate the consequences of Lorentz violation (as expressed within the gravity sector of the Standard-Model Extension) upon the gravitational quantum states of ultracold neutrons (UCNs). Since our main aim is to compare our theoretical results ... More
Local effects of the quantum vacuum in Lorentz-violating electrodynamicsNov 14 2016The Casimir effect is one of the most remarkable consequences of the non-zero vacuum energy predicted by quantum field theory. In this paper we use a local approach to study the Lorentz violation effects of the minimal standard model extension on the ... More
Two charges on plane in a magnetic field: special trajectoriesAug 14 2012A classical mechanics of two Coulomb charges on a plane $(e_1, m_1)$ and $(e_2, m_2)$ subject to a constant magnetic field perpendicular to a plane is considered. Special "superintegrable" trajectories (circular and linear) for which the distance between ... More
Dirac's method for time-dependent Hamiltonian systems in the extended phase spaceJan 25 2017The Dirac's method for constrained systems is applied to the analysis of time-dependent Hamiltonians in the extended phase space. Our analysis provides a conceptually complete description and offers a different point of view of earlier works. We show ... More
A general existence result for the Toda system on compact surfacesJun 23 2013Sep 02 2015In this paper we consider the Toda system of equations on a compact surface, which is motivated by the study of models in non-abelian Chern-Simons theory. We prove a general existence result using variational methods. The same analysis applies to a mean ... More
Toward Real-Time Decentralized Reinforcement Learning using Finite Support Basis FunctionsJun 20 2017This paper addresses the design and implementation of complex Reinforcement Learning (RL) behaviors where multi-dimensional action spaces are involved, as well as the need to execute the behaviors in real-time using robotic platforms with limited computational ... More
The ALMA Early Science View of FUor/EXor objects. IV. Misaligned Outflows in the Complex Star-forming Environment of V1647 Ori and McNeil's NebulaSep 06 2017We present Atacama Large Millimeter/sub-millimeter Array (ALMA) observations of the star-forming environment surrounding V1647 Ori, an outbursting FUor/EXor pre-MS star. Dust continuum and the (J = 2 - 1) $^{12}$CO, $^{13}$CO, C$^{18}$O molecular emission ... More
3D Spin Glass and 2D Ferromagnetic XY Model: a ComparisonJul 04 1997We compare the probability distributions and Binder cumulants of the overlap in the 3D Ising spin glass with those of the magnetization in the ferromagnetic 2D XY model. We analyze similarities and differences. Evidence for the existence of a phase transition ... More
Compactness, existence and multiplicity for the singular mean field problem with sign-changing potentialsDec 07 2016In this paper we consider a mean field problem on a compact surface with conical singularities. This problem appears in the Gaussian curvature prescription problem in Geometry, and also in the Electroweak Theory and in the abelian Chern-Simons-Higgs model ... More
Classical analog of the quantum metric tensorNov 22 2018Apr 02 2019We present a classical analog of the quantum metric tensor, which is defined for classical integrable systems that undergo an adiabatic evolution governed by slowly varying parameters. This classical metric measures the distance, on the parameter space, ... More
The Asymptotic Behavior of the Composition of Firmly Nonexpansive MappingsNov 25 2014In this paper we provide a unified treatment of some convex minimization problems, which allows for a better understanding and, in some cases, improvement of results in this direction proved recently in spaces of curvature bounded above. For this purpose, ... More
The Generalized Reparameterization GradientOct 07 2016Oct 14 2016The reparameterization gradient has become a widely used method to obtain Monte Carlo gradients to optimize the variational objective. However, this technique does not easily apply to commonly used distributions such as beta or gamma without further approximations, ... More
Curvaton DynamicsAug 01 2003In contrast to the inflaton's case, the curvature perturbations due to the curvaton field depend strongly on the evolution of the curvaton before its decay. We study in detail the dynamics of the curvaton evolution during and after inflation. We consider ... More
The Peccei-Quinn Field as CurvatonMar 18 2003Jun 02 2003A simple extension of the minimal supersymmetric standard model which naturally and simultaneously solves the strong CP and mu problems via a Peccei-Quinn and a continuous R symmetry is considered. This model is supplemented with hybrid inflation and ... More
Classical analog of the quantum information metricNov 22 2018We present a classical analog of the quantum information metric, which is defined for classical integrable systems that undergo an adiabatic evolution governed by slowly varying parameters. This classical metric measures the distance, on the parameter ... More
Bound state spectra and properties of the doublet states in three-electron atomic systemsMar 31 2014Jun 16 2014The bound state spectra of the doublet states in three-electron atomic systems are investigated. By using different variational expansions we determine various bound state properties in these systems. Such properties include the electron-nucleus and electron-electron ... More
Stability estimates for the Calderón problem with partial dataMay 06 2014This is a follow-up of a previous article where we proved local stability estimates for a potential in a Schr\"odinger equation on an open bounded set in dimension $n=3$ from the Dirichlet-to-Neumann map with partial data. The region under control was ... More
Stability estimates for the Radon transform with restricted data and applicationsNov 08 2012Dec 14 2012In this article, we prove a stability estimate going from the Radon transform of a function with limited angle-distance data to the $L^p$ norm of the function itself, under some conditions on the support of the function. We apply this theorem to obtain ... More
The Single-Degenerate Scenario for Type Ia SNe in Cosmic PerspectiveNov 28 1995The occurrence and properties of Type Ia supernovae (SNe Ia) in single-degenerate binary systems (white dwarf [WD] + nondegenerate companion) is examined for galaxies of different types, and as a function of redshift. The rates and characteristics (peak ... More
Type Ia Supernova Scenarios and the Hubble SequenceMay 19 1995The dependence of the Type Ia supernova (SN Ia) rate on galaxy type is examined for three currently proposed scenarios: merging of a Chandrasekhar--mass CO white dwarf (WD) with a CO WD companion, explosion of a sub--Chandrasekhar mass CO WD induced by ... More
Renormalization and Universality of Van der Waals forcesDec 14 2009Renormalization ideas can profitably be exploited in conjunction with the superposition principle of boundary conditions in the description of model independent and universal scaling features of the singular and long range Van der Waals force between ... More
Low energy universality and scaling of Van der Waals forcesDec 09 2009At long distances interactions between neutral ground state atoms can be described by the Van der Waals potential V(r) =-C6/r^6-C8/r^8 - ... . In the ultra-cold regime atom-atom scattering is dominated by s-waves phase shifts given by an effective range ... More
Old nuclear symmetries and large N(c) as long distance symmetries in the two nucleon systemApr 27 2009Wigner and Serber symmetries for the two-nucleon system provide unique examples of long distance symmetries in Nuclear Physics, i.e. symmetries of the meson exchange forces broken only at arbitrarily small distances. We analyze the large Nc picture as ... More
Flaring up: radio diagnostics of the kinematic, hydrodynamic and environmental properties of GRBsOct 23 2002Oct 17 2003The specific incidence of radio flares appears to be significantly larger than that of the prompt optical emission. This abundance, coupled with the reverse shock interpretation suggests that radio flares add a unique probe on the physics of GRB shocks. ... More
On four state Hard Core Models on the Cayley TreeOct 24 2012Oct 14 2014We consider a nearest-neighbor four state hard-core (HC) model on the homogeneous Cayley tree of order $k$. The Hamiltonian of the model is considered on a set of "admissible" configurations. Admissibility is specified through a graph with four vertices. ... More
On four state Hard Core Models on the Cayley TreeOct 24 2012Feb 24 2017We consider a nearest-neighbor four state hard-core (HC) model on the homogeneous Cayley tree of order $k$. The Hamiltonian of the model is considered on a set of "admissible" configurations. Admissibility is specified through a graph with four vertices. ... More
Quantum correlations and energy currents across finite harmonic chainsMar 31 2015We present a study that addresses both the stationary properties of the energy current and quantum correlations in a three-mode chain subjected to Ohmic and super-Ohmic dissipa- tions. An extensive numerical analysis shows that the mean value and the ... More
Thoughts on Duality and Fundamental ConstantsDec 20 2005May 07 2007We consider some fundamental constants from the point of view of the duality symmetry. Our analysis of duality is focused on three issues: the maximum radiated power of gravitational waves, the cosmological constant, and the magnetic monopole mass. We ... More
Spectroscopic analysis of DA white dwarfs from the McCook & Sion catalogOct 29 2008For some years now, we have been gathering optical spectra of DA white dwarfs in an effort to study and define the empirical ZZ Ceti instability strip. However, we have recently expanded this survey to include all the DA white dwarfs in the McCook & Sion ... More
Can rigidly rotating polytropes be sources of the Kerr metric?Sep 07 2007We use a recent result by Cabezas et al. to build up an approximate solution to the gravitational field created by a rigidly rotating polytrope. We solve the linearized Einstein equations inside and outside the surface of zero pressure including second-order ... More
Multipeak solutions for the Yamabe equationJul 22 2018Aug 21 2018Let $(M,g)$ be a closed Riemannian manifold of dimension $n\geq 3$ and $x_0 \in M$ be an isolated local minimum of the scalar curvature $s_g$ of $g$. For any positive integer $k$ we prove that for $\epsilon >0$ small enough the subcritical Yamabe equation ... More
Toward a classification of semidegenerate 3D superintegrable systemsNov 09 2016Superintegrable systems of 2nd order in 3 dimensions with exactly 3-parameter potentials are intriguing objects. Next to the nondegenerate 4-parameter potential systems they admit the maximum number of symmetry operators but their symmetry algebras don't ... More
Reconstruction of compacta by finite approximations and Inverse PersistenceFeb 12 2018Feb 27 2018The aim of this paper is to show how the homotopy type of compact metric spaces can be reconstructed by the inverse limit of an inverse sequence of finite approximations of the corresponding space. This recovering allows us to define inverse persistence ... More
Simulation of 3d Ising spin glass model using three replicas: study of Binder cumulantsMar 12 1996We have carried out numerical simulations of the three-dimensional Ising spin glass model with first neighbour Gaussian couplings using three replicas for each sample of couplings. We have paid special attention to the measure of two types of Binder cumulant ... More