Results for "Fernando A. Oliveira"

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Growth exponents of the etching model in high dimensionsJul 18 2017In this work we generalize the etching model (Mello et al 2001 Phys. Rev. E 63 041113) to d + 1 dimensions. The dynamic exponents of this model are compatible with those of the Kardar-Parisi-Zhang universality class. We investigate the roughness dynamics ... More
Critical behavior of noise-induced phase synchronizationJun 26 2016In this article, we present a systematic study of the critical behavior of phase oscillators with multiplicative noise from a thermodynamic equilibrium approach. We have already presented the thermodynamics of phase noise oscillators and mapped out in ... More
On the Transitivity of Invariant Manifolds of Conservative FlowsFeb 28 2015Dec 08 2016The main result of this work is the following: for volume preserving flows on compact manifolds with the $C^r$ topology, $1 \leqq r \leqq \infty$ , the closure of every invariant manifold of periodic orbits and singularities is a chain transitive set. ... More
Residual entropy and waterlike anomalies in the repulsive one dimensional lattice gasMar 10 2015The thermodynamic and kinetics of the one dimensional lattice gas with repulsive interaction is investigated using transfer matrix technique and Monte Carlo simulations. This simple model is shown to exhibit waterlike anomalies in density, thermal expansion ... More
An analytical formulation for roughness based on celular automataAug 24 2012Aug 29 2012We present a method to derive the analytical expression of the roughness of a fractal surface whose dynamics is ruled by cellular automata. Starting from the automata, we write down the the time derivative of the height's average and variance. By assuming ... More
Mixing, ergodicity and slow relaxation phenomenaOct 10 2006Oct 20 2006Investigations on diffusion in systems with memory [I.V.L. Costa, R. Morgado, M.V.B.T. Lima, F.A. Oliveira, Europhys. Lett. 63 (2003) 173] have established a hierarchical connection between mixing, ergodicity, and the fluctuation-dissipation theorem (FDT). ... More
Pendular behavior of public transport networksJul 18 2017In this paper, we propose a methodology that bears close resemblance to the Fourier analysis of the first harmonic to study networks subjected to pendular behavior. In this context, pendular behavior is characterized by the phenomenon of people's dislocation ... More
Anomalous diffusion: A basic mechanism for the evolution of inhomogeneous systemsFeb 08 2019In this article we review classical and recent results in anomalous diffusion and provide mechanisms useful for the study of the fundamentals of certain processes, mainly in condensed matter physics, chemistry and biology. Emphasis will be given to some ... More
Intermediate dynamics between Newton and LangevinDec 04 2006A dynamics between Newton and Langevin formalisms is elucidated within the framework of the generalized Langevin equation. For thermal noise yielding a vanishing zero-frequency friction the corresponding non-Markovian Brownian dynamics exhibits anomalous ... More
Flow in Rough Self-Affine Fractures JointsAug 30 2006We investigate viscous and non-viscous flow in two-dimensional self-affine fracture joints through direct numerical simulations of the Navier-Stokes equations. As a novel hydrodynamic feature of this flow system, we find that the effective permeability ... More
A Formal Evaluation of PSNR as Quality Measurement Parameter for Image Segmentation AlgorithmsMay 23 2016Quality evaluation of image segmentation algorithms are still subject of debate and research. Currently, there is no generic metric that could be applied to any algorithm reliably. This article contains an evaluation for the PSRN (Peak Signal-To-Noise ... More
Breakdown of the Fluctuation-Dissipation Theorem for fast superdiffusionJul 30 2002We study anomalous diffusion for one-dimensional systems described by a generalized Langevin equation. We show that superdiffusion can be classified in slow superdiffusion and fast superdiffusion. For fast superdiffusion we prove that the Fluctuation-Dissipation ... More
Nonergodic Brownian Dynamics and the Fluctuation-Dissipation TheoremMay 03 2006Nonergodic Brownian motion is elucidated within the framework of the generalized Langevin equation. For thermal noise yielding either a vanishing or a divergent zero-frequency friction strength, the non-Markovian Browninan dynamics exhibits a riveting, ... More
Anomalous law of coolingDec 15 2014Mar 04 2015We analyze the temperature relaxation phenomena of systems in contact with a thermal reservoir that undergo a non-Markovian diffusion process. From a generalized Langevin equation, we show that the temperature is governed by a law of cooling of the Newton's ... More
Non-exponential relaxation for anomalous diffusionJan 21 2005May 04 2006We study the relaxation process in normal and anomalous diffusion regimes for systems described by a generalized Langevin equation (GLE). We demonstrate the existence of a very general correlation function which describes the relaxation phenomena. Such ... More
Violation of the fluctuation-dissipation theorem for fast superdiffusionApr 11 2003We study anomalous diffusion for one-dimensional systems described by a generalized Langevin equation. We show that superdiffusion can be classified in normal superdiffusion and fast superdiffusion. For fast superdiffusion, we prove that the Fluctuation-Dissipation ... More
Analysis of etching at a solid-solid interfaceJul 18 2017We present a method to derive an analytical expression for the roughness of an eroded surface whose dynamics are ruled by cellular automaton. Starting from the automaton, we obtain the time evolution of the height average and height variance (roughness). ... More
Pattern transitions in a nonlocal logistic map for populationsJan 26 2016Sep 14 2016In this work, we study the pattern solutions of doubly nonlocal logistic map that include spatial kernels in both growth and competition terms. We show that this map includes as a particular case the nonlocal Fisher-Kolmogorov equation, and we demonstrate ... More
A quantitative version of Steinhaus' theorem for compact, connected, rank-one symmetric spacesMay 04 2010Jan 10 2013Let $d_1$, $d_2$, ... be a sequence of positive numbers that converges to zero. A generalization of Steinhaus' theorem due to Weil implies that, if a subset of a homogeneous Riemannian manifold has no pair of points at distances $d_1$, $d_2$, ... from ... More
Tight Bounds for the Entanglement of Formation of Gaussian StatesOct 22 2013Jan 31 2014We establish tight upper and lower bounds for the Entanglement of Formation of an arbitrary two-mode Gaussian state employing necessary properties of Gaussian channels. Both bounds are strictly given by the Entanglement of Formation of symmetric Gaussian ... More
Solving Irregular Strip Packing Problems With Free Rotations Using Separation LinesJul 22 2017Solving nesting problems or irregular strip packing problems is to position polygons in a fixed width and unlimited length strip, obeying polygon integrity containment constraints and non-overlapping constraints, in order to minimize the used length of ... More
Computing upper bounds for the packing density of congruent copies of a convex bodyAug 22 2013Jul 06 2016In this paper we prove a theorem that provides an upper bound for the density of packings of congruent copies of a given convex body in $\mathbb{R}^n$; this theorem is a generalization of the linear programming bound for sphere packings. We illustrate ... More
A counterexample to a conjecture of Larman and Rogers on sets avoiding distance 1Aug 22 2018For $n \geq 2$ we construct a measurable subset of the unit ball in $\mathbb{R}^n$ that does not contain pairs of points at distance 1 and whose volume is greater than $(1/2)^n$ times the volume of the ball. This disproves a conjecture of Larman and Rogers ... More
On the integrality gap of the maximum-cut semidefinite programming relaxation in fixed dimensionAug 07 2018We describe a factor-revealing convex optimization problem for the integrality gap of the maximum-cut semidefinite programming relaxation: for each $n \geq 2$ we present a convex optimization problem whose optimal value is the largest possible ratio between ... More
A counterexample to a conjecture of Larman and Rogers on sets avoiding distance 1Aug 22 2018Mar 11 2019For $n \geq 2$ we construct a measurable subset of the unit ball in $\mathbb{R}^n$ that does not contain pairs of points at distance 1 and whose volume is greater than $(1/2)^n$ times the volume of the ball. This disproves a conjecture of Larman and Rogers ... More
Torelli theorem for the moduli spaces of rank 2 quadratic pairsJun 18 2012Feb 01 2014Let $X$ be a smooth projective complex curve. We prove that a Torelli type theorem holds, under certain conditions, for the moduli space of $\alpha$-polystable quadratic pairs on $X$ of rank 2.
A variational problem associated to a hyperbolic Caffarelli--Kohn--Nirenberg inequalityNov 16 2017We prove a Caffarelli--Kohn--Nirenberg inequality in the hyperbolic space. For a semilinear elliptic equation involving the associated weighted Laplace--Beltrami operator, we establish variationally the existence of positive radial solutions in the subcritical ... More
Grothendieck inequalities for semidefinite programs with rank constraintNov 08 2010May 04 2012Grothendieck inequalities are fundamental inequalities which are frequently used in many areas of mathematics and computer science. They can be interpreted as upper bounds for the integrality gap between two optimization problems: a difficult semidefinite ... More
Minkowski structure for purity and entanglement of Gaussian bipartite statesOct 24 2013The relation between the symplectic and Lorentz groups is explored to investigate entanglement features in a two-mode bipartite Gaussian state. We verify that the correlation matrix of arbitrary Gaussian states can be associated to a hyperbolic space ... More
The zero-inflated promotion cure rate regression model applied to fraud propensity in bank loan applicationsOct 01 2015In this paper we extend the promotion cure rate model proposed by Chen et al (1999), by incorporating excess of zeros in the modelling. Despite allowing to relate the covariates to the fraction of cure, the current approach, which is based on a biological ... More
The zero-inflated cure rate regression model: Applications to fraud detection in bank loan portfoliosSep 17 2015Sep 19 2015In this paper, we introduce a methodology based on the zero-inflated cure rate model to detect fraudsters in bank loan applications. In fact, our approach enables us to accommodate three different types of loan applicants, i.e., fraudsters, those who ... More
Positive solutions of quasilinear elliptic equations with exponential nonlinearity combined with convection termAug 27 2018We establish the existence of positive solutions for a nonlinear elliptic Dirichlet problem in dimension $N$ involving the $N$-Laplacian. The nonlinearity considered depends on the gradient of the unknown function and an exponential term. In such case, ... More
Improving the semidefinite programming bound for the kissing number by exploiting polynomial symmetrySep 16 2016The kissing number of $\mathbb{R}^n$ is the maximum number of pairwise-nonoverlapping unit spheres that can simultaneously touch a central unit sphere. Mittelmann and Vallentin (2010), based on the semidefinite programming bound of Bachoc and Vallentin ... More
Accuracy of generalized gradient approximation functionals for density functional perturbation theory calculationsSep 18 2013We assess the validity of various exchange-correlation functionals for computing the structural, vibrational, dielectric, and thermodynamical properties of materials in the framework of density-functional perturbation theory (DFPT). We consider five generalized-gradient ... More
The asymptotic analysis of a Darcy-Stokes system coupled through a curved interfaceFeb 22 2019The asymptotic analysis of a Darcy-Stokes system modeling the fluid exchange between a narrow channel (Stokes) and a porous medium (Darcy) coupled through a $ C^{2} $ curved interface, is presented. The channel is a cylindrical domain between the interface ... More
Systematic reduction of sign errors in many-body problems: generalization of self-healing diffusion Monte Carlo to excited statesJun 24 2009Aug 16 2009A recently developed self-healing diffusion Monte Carlo algorithm [PRB 79, 195117] is extended to the calculation of excited states. The formalism is based on an excited-state fixed-node approximation and the mixed estimator of the excited-state probability ... More
On the Construction of Geometric Parameters for Preferential Fluid Flow Information in Fissured MediaFeb 19 2014For a fissured medium, we analyze the impact that the geometry of the cracks, has in the phenomenon of preferential fluid flow. Using finite volume meshes we analyze the mechanical energy dissipation due to gravity, curvature of the surface and friction ... More
On the Homogenization of Geological Fissured Systems With Curved non-periodic CracksDec 14 2013We analyze the steady fluid flow in a porous medium containing a network of thin fissures i.e. width $\mathcal{O}(\epsilon)$, where all the cracks are generated by the rigid translation of a continuous piecewise $C^{1}$ functions in a fixed direction. ... More
A Conforming Primal-Dual Mixed Formulation for the 2D Multiscale Porous Media Flow ProblemJan 04 2017Oct 02 2018In this paper a new primal-dual mixed finite element method is introduced, aimed to model multiscale problems with several geometric subregions in the domain of interest. In each of these regions porous media fluid flow takes place, but governed by physical ... More
Velocity measurements in General Relativity revisitedJul 14 2011In this work we generalize an earlier treatment of the measurements of velocities at the event horizon of a black hole. This is intended as a pedagogical exercise as well as one more contribution to the resolution of some unphysical interpretations related ... More
Modified Theories of Gravity: Traversable WormholesJul 13 2011This MSc thesis is divided in to two parts. The first, covers the foundations of theories of gravitation, and, the second incorporates original work on the subject of the existence of traversable wormholes in $f(R)$ modified theories of gravity. A short ... More
Atomic topology and radial distribution functions of a-SiNxOct 17 2001We report a new approach to simulate amorphous networks of covalently bonded materials that leads to excellent radial distribution functions and realistic atomic arrangements. We apply it to generate the first ab initio structures of nitrogen-doped silicon, ... More
On pointed Hopf algebras associated to unmixed conjugacy classes in S_nAug 28 2006Let s in S_n be a product of disjoint cycles of the same length, C the conjugacy class of s and rho an irreducible representation of the isotropy group of s. We prove that either the Nichols algebra B(C, rho) is infinite-dimensional, or the braiding of ... More
Robust Output Regulation of Linear Passive Systems with Multivalued Upper Semicontinuous ControlsDec 05 2014The use of multivalued controls derived from a special maximal monotone operator are studied in this note. Starting with a strictly passive linear system (with possible parametric uncertainty and external disturbances) a multivalued control law is derived, ... More
Pulsars in Globular ClustersJan 12 2005More than 100 radio pulsars have been detected in 24 globular clusters. The largest observed samples are in Terzan 5 and 47 Tucanae, which together contain 45 pulsars. Accurate timing solutions, including positions in the cluster, are known for many of ... More
New assessment on the nonlocality of correlation boxesMay 15 2016Correlation boxes are hypothetical systems capable of producing the maximal algebraic violation of Bell inequalities, beyond the quantum bound and without superluminal signaling. The fact that these systems show stronger correlations than those presented ... More
Bell states and entanglement dynamics on two coupled quantum moleculesMar 03 2015Mar 06 2015This work provides a complete description of entanglement properties between electrons inside coupled quantum molecules, nanoestructures which consist of two quantum dots. Each electron can tunnel between the two quantum dots inside the molecule, being ... More
Impact of interactions on human dynamicsOct 25 2007Aug 05 2008Queueing theory has been recently proposed as a framework to model the heavy tailed statistics of human activity patterns. The main predictions are the existence of a power-law distribution for the interevent time of human actions and two decay exponents ... More
A New Version of Dirac's AEther and Its Cosmological ApplicationsDec 27 2002We propose a new formulation for the AEther of Dirac based on a lagrangian approach. We analyse how the presence of a particular self-interaction term in the lagrangian lead us to a description of the aether as being a medium with conductivity which is ... More
Canonical formulation of Poincare BFCG theory and its quantizationSep 12 2014Mar 29 2015We find the canonical formulation of the Poincare BFCG theory in terms of the spatial 2-connection and its canonically conjugate momenta. We show that the Poincare BFCG action is dynamically equivalent to the BF action for the Poincare group and we find ... More
Spin-Orbit Coupling in Diamond and Zincblende HeterostructuresJul 12 2004Spin splittings in III-V materials and heterostructures are of interest because of potential applications, mainly in spintronic devices. A necessary condition for the existence of these spin splittings is the absence of inversion symmetry. In bulk zincblende ... More
Mass and Extremals Associated with the Hardy-Schrödinger Operator on Hyperbolic SpaceOct 03 2017Apr 05 2018We consider the Hardy-Schr\"odinger operator $ -\Delta_{\mathbb{B}^n}-\gamma{V_2}$ on the Poincar\'e ball model of the Hyperbolic space ${\mathbb{B}^n}$ ($n \geq 3$). Here $V_2$ is a well chosen radially symmetric potential, which behaves like the Hardy ... More
Flag Algebras: A First GlanceJul 16 2016The theory of flag algebras, introduced by Razborov in 2007, has opened the way to a systematic approach to the development of computer-assisted proofs in extremal combinatorics. It makes it possible to derive bounds for parameters in extremal combinatorics ... More
$k$-point semidefinite programming bounds for equiangular linesDec 14 2018In this paper we derive a hierarchy of $k$-point semidefinite programming upper bounds for the maximum number of equiangular lines in $n$-dimensional Euclidean space. We apply symmetry reduction techniques for invariant semidefinite programs to compute ... More
Experimental investigation of the softening-stiffening response of tensegrity prisms under compressive loadingJun 04 2014Jun 21 2014The present paper is concerned with the formulation of new assembly methods of bi-material tensegrity prisms, and the experimental characterization of the compressive response of such structures. The presented assembly techniques are easy to implement, ... More
Improving Graphene-metal Contacts: Thermal Induced PolishingJan 15 2018Graphene is a very promising material for nanoelectronics applications due to its unique and remarkable electronic and thermal properties. However, when deposited on metallic electrodes the overall thermal conductivity is significantly decreased. This ... More
Spectral bounds for the independence ratio and the chromatic number of an operatorJan 06 2013Jun 19 2013We define the independence ratio and the chromatic number for bounded, self-adjoint operators on an L^2-space by extending the definitions for the adjacency matrix of finite graphs. In analogy to the Hoffman bounds for finite graphs, we give bounds for ... More
Silver Hardening via Hypersonic ImpactsJan 15 2018The search for new ultra strong materials has been a very active research area. With relation to metals, a successful way to improve their strength is by the creation of a gradient of nanograins (GNG) inside the material. Recently, R. Thevamaran et al. ... More
Evolution of Collective Behaviors for a Real Swarm of Aquatic Surface RobotsNov 10 2015Feb 02 2016Swarm robotics is a promising approach for the coordination of large numbers of robots. While previous studies have shown that evolutionary robotics techniques can be applied to obtain robust and efficient self-organized behaviors for robot swarms, most ... More
Turbulent channel flow perturbed by triangular ripplesFeb 28 2018Mar 15 2018This paper presents an experimental investigation of the perturbation of a turbulent closed-conduit flow by two-dimensional triangular ripples. Two ripple configurations were employed: one single asymmetric triangular ripple, and two consecutive asymmetric ... More
Lower bounds for measurable chromatic numbersJan 07 2008Jul 17 2009The Lovasz theta function provides a lower bound for the chromatic number of finite graphs based on the solution of a semidefinite program. In this paper we generalize it so that it gives a lower bound for the measurable chromatic number of distance graphs ... More
Better bounds for planar sets avoiding unit distancesDec 31 2014Oct 26 2015A $1$-avoiding set is a subset of $\mathbb{R}^n$ that does not contain pairs of points at distance $1$. Let $m_1(\mathbb{R}^n)$ denote the maximum fraction of $\mathbb{R}^n$ that can be covered by a measurable $1$-avoiding set. We prove two results. First, ... More
Finite-Size Effects in the Absorption Spectra of a Single-Wall Carbon NanotubeDec 13 2017The determination of the optical spectrum of single-wall carbon nanotubes (SWCNTs) is essential for the development of opto-electronic components and sensors with application in many fields. Real SWCNTs are finite, but almost all the studies performed ... More
Surface and bulk properties of ballistic deposition models with bond breakingAug 08 2012Feb 17 2013We introduce a new class of growth models, with a surface restructuring mechanism in which impinging particles may dislodge suspended particles, previously aggregated on the same column in the deposit. The flux of these particles is controlled through ... More
On the Implementation and Assessment of several Divide & Conquer Matheuristic Strategies for the solution of the Knapsack ProblemJan 04 2019We introduce and asses a Divide \& Conquer heuristic method, aimed to solve large instances of the Knapsack Problem. The method subdivides a large problem in two smaller ones (or recursive iterations of the same principle), to lower down the global computational ... More
On the generation of bipartite grids with controlled regularity for 2-D and 3-D simply connected domainsDec 25 2013We present a procedure to generate bipartite grids for simply connected domains in 2-D and 3-D of prescribed size and controlled regularity elements. The mesh elements $K$ of the triangulation satisfy $\zeta_{K} \leq C$ where $\zeta_{K}$ is the regularity ... More
Asymptotic behavior of Boussinesq system of KdV-KdV typeSep 18 2017This work deals with the local rapid exponential stabilization for a Boussinesq system of KdV-KdV type introduced by J. Bona, M. Chen and J.-C. Saut. This is a model for the motion of small amplitude long waves on the surface of an ideal fluid. Here, ... More
Open string with a background B-field as the first order mechanics and noncommutativityOct 19 2001To study noncommutativity properties of the open string with constant B-field we construct a mechanical action which reproduces classical dynamics of the string sector under consideration. It allows one to apply the Dirac quantization procedure for constrained ... More
Hidden sector effects on double higgs production near threshold at the LHCSep 22 2010Aug 09 2011In this letter we study a novel effect of a hidden sector coupling to the standard model Higgs boson: an enhancement of the Higgs pair production cross section near threshold due to bound state effects. After summing the ladder contributions of the hidden ... More
Tangential Fluid flow within 3D narrow fissures: Conservative velocity fields on associated triangulations and transport processesNov 28 2016Oct 02 2018For a fissured medium with uncertainty in the knowledge of fractures' geometry, a conservative tangential flow field is constructed, which is consistent with the physics of stationary fluid flow in porous media and an interpolated geometry of the cracks. ... More
Min-max piecewise constant optimal control for multi-model linear systemsDec 12 2014The present work addresses a finite-horizon linear-quadratic optimal control problem for uncertain systems driven by piecewise constant controls. The precise values of the system parameters are unknown, but assumed to belong to a finite set (i.e., there ... More
Torsion effects on Condensed Matter: like a magnetic field but not so muchJan 07 2017In this work, we study the effects of torsion due to a uniform distribution of topological defects (screw dislocations) on free spin/carrier dynamics in elastic solids. When a particle moves in such a medium, the effect of the torsion associated to the ... More
Space-Time Block Diagonalization for Frequency-Selective MIMO Broadcast ChannelsAug 21 2016The most relevant linear precoding method for frequency-flat MIMO broadcast channels is block diagonalization (BD) which, under certain conditions, attains the same nonlinear dirty paper coding channel capacity. However, BD is not easily translated to ... More
The Interaction Between PDE and Graphs in Multiscale ModelingMay 27 2015Apr 18 2016In this article an upscaled model is presented, for complex networks with highly clustered regions exchanging some abstract quantities in both, microscale and macroscale level. Such an intricate system is approximated by a partitioned open map in $\mathbb{R}^{2}$ ... More
A Darcy-Brinkman Model of Fractures in Porous MediaNov 16 2016For a fully-coupled Darcy-Stokes system describing the exchange of fluid and stress balance across the interface between a saturated porous medium and an open very narrow channel, the limiting problem is characterized as the width of the channel converges ... More
Diffusion Processes Homogenization for Scale-Free Metric NetworksSep 15 2015May 29 2016This work discusses the homogenization analysis for diffusion processes on scale-free metric graphs, using weak variational formulations. The oscillations of the diffusion coefficient along the edges of a metric graph induce internal singularities in ... More
A Discussion on the Transmission Conditions for Saturated Fluid Flow Through Porous Media With Fractal MicrostructureNov 26 2015Oct 24 2018The present work is aimed to find suitable exchange conditions for saturated fluid flow in a porous medium, when a fractal microstructure is embedded in the porous matrix. Two different deterministic models are introduced and rigorously analyzed. Also, ... More
Spin Dependence of Heavy Quark FragmentationFeb 28 2007We propose that the non-perturbative fragmentation functions describing the transition from a heavy quark to a heavy meson is proportional to the square of the produced meson wave function at the origin. We analyze the effects of this proposal on the ... More
Fifty Shades of Congestion Control: A Performance and Interactions EvaluationMar 09 2019Congestion control algorithms are crucial in achieving high utilization while preventing overloading the network. Over the years, many different congestion control algorithms have been developed, each trying to improve in specific situations. However, ... More
Learning Attribute Representation for Human Activity RecognitionFeb 02 2018Attribute representations became relevant in image recognition and word spotting, providing support under the presence of unbalance and disjoint datasets. However, for human activity recognition using sequential data from on-body sensors, human-labeled ... More
Dynamically Correcting a CNOT Gate for any Systematic Logical ErrorJul 15 2016Apr 10 2017We derive a set of composite pulse sequences that generates CNOT gates and correct all systematic errors within the logical subspace to arbitrary order. These sequences are applicable for any two-qubit interaction Hamiltonian, and make no assumptions ... More
On the Stability of the Cauchy Problem of Timoshenko Thermoelastic Systems with Past History: Cattaneo and Fourier LawAug 26 2018In this paper, we investigate the decay properties of the thermoelastic Timoshenko system with past history in the whole space where the thermal effects are given by Cattaneo and Fourier laws. We obtain that both systems, Timoshenko-Fourier and Timoshenko-Cattaneo, ... More
Case-Factor Diagrams for Structured Probabilistic ModelingJul 11 2012We introduce a probabilistic formalism subsuming Markov random fields of bounded tree width and probabilistic context free grammars. Our models are based on a representation of Boolean formulas that we call case-factor diagrams (CFDs). CFDs are similar ... More
Optimal design of composite granular protectorsFeb 10 2008Dec 04 2008We employ an evolutionary algorithm to investigate the optimal design of composite protectors using one-dimensional granular chains composed of beads of various sizes, masses, and stiffnesses. We define a fitness function using the maximum force transmitted ... More
Coherence and Entanglement in a Stern-Gerlach experimentAug 24 2006We give a simple example of the tight connection between entanglement and coherence for pure bipartite systems showing the double role played by entanglement; it allows for the creation of superpositions of macroscopic objects but at the same time makes ... More
Hamiltonian analysis of the BFCG theory for the Poincare 2-groupAug 23 2015Feb 25 2016We perform the full Hamiltonian analysis of the topological BFCG action based on the Poincare 2-group. The Hamiltonian of the theory is constructed, and the algebra of constraints is computed. The Dirac brackets are evaluated, and the second class constraints ... More
Continuous Measurement of Atom-Number Moments of a Bose-Einstein Condensate by PhotodetectionJul 10 2003Jul 20 2004We propose a measurement scheme that allows determination of even-moments of a Bose-Einstein condensate (BEC) atom number, in a ring cavity, by continuous photodetection of an off-resonant quantized optical field. A fast cavity photocounting process limits ... More
Hamiltonian analysis of the BFCG formulation of General RelativityJul 17 2018Dec 03 2018We perform the complete Hamiltonian analysis of the BFCG action for General Relativity. We determine all the constraints of the theory and classify them into the first-class and the second-class constraints. We also show how the canonical formulation ... More
Spectral and Localization Properties for the One-Dimensional Bernoulli Discrete Dirac OperatorMay 18 2005A 1D Dirac tight-binding model is considered and it is shown that its nonrelativistic limit is the 1D discrete Schr?odinger model. For random Bernoulli potentials taking two values (without correlations), for typical realizations and for all values of ... More
Mathematical predominance of Dirichlet condition for the one-dimensional Coulomb potentialMay 29 2012We restrict a quantum particle under a coulombian potential (i.e., the Schr\"odinger operator with inverse of the distance potential) to three dimensional tubes along the x-axis and diameter $\varepsilon$, and study the confining limit $\varepsilon\to0$. ... More
Reliability of digitized quantum annealing and the decay of entanglementNov 01 2016We performed a banged-digital-analog simulation of a quantum annealing protocol in a two-qubit Nuclear Magnetic Resonance (NMR) quantum computer. Our experimental simulation employed up to 235 Trotter steps, with more than 2000 gates (pulses), and we ... More
Optical and magnetic excitations of metal-encapsulating Si cages: A systematic study by time-dependent density functional theorySep 23 2013Systematic study of the optical and magnetic excitations of twelve MSi$_{12}$ and four MSi$_{10}$ transition metal encapsulating Si cages has been carried out by employing real time time-dependent density functional theory. Criteria for the choice of ... More
Mather problem and viscosity solutions in the stationary settingMar 09 2009In this paper we discuss the Mather problem for stationary Lagrangians, that is Lagrangians $L:\Rr^n\times \Rr^n\times \Omega\to \Rr$, where $\Omega$ is a compact metric space on which $\Rr^n$ acts through an action which leaves $L$ invariant. This setting ... More
Mass Terms in Two-Higgs Doublet ModelsDec 14 2001Feb 11 2003We take a closer look at the mass terms of all renormalizable and CP conserving two-Higgs doublet models (THDM). We show how some of the dimension two parameters in the potential can be set equal to zero leading to relations among the tree-level parameters ... More
On the spectrum and weakly effective operator for Dirichlet Laplacian in thin deformed tubesMar 15 2011We study the Laplacian in deformed thin (bounded or unbounded) tubes in ?$\R^3$, i.e., tubular regions along a curve $r(s)$ whose cross sections are multiplied by an appropriate deformation function $h(s)> 0$. One the main requirements on $h(s)$ is that ... More
Noncommutative cosmological model in the presence of a phantom fluidJan 04 2017We study noncommutative classical Friedmann-Robertson-Walker cosmological models. The constant curvature of the spatial sections can be positive ($k=1$), negative ($k=-1$) or zero ($k=0$). The matter is represented by a perfect fluid with negative pressure, ... More
Retinal vessel segmentation based on Fully Convolutional Neural NetworksDec 18 2018Dec 19 2018The retinal vascular condition is a reliable biomarker of several ophthalmologic and cardiovascular diseases, so automatic vessel segmentation may be crucial to diagnose and monitor them. In this paper, we propose a novel method that combines the multiscale ... More
CAL 87 - an evolved wind-driven supersoft X-ray binaryJul 23 2007Compact binary supersoft X-ray sources (CBSS) are explained as being associated with hydrostatic nuclear burning on the surface of a white dwarf with high accretion rate. This high mass transfer rate has been suggested to be caused by dynamical instability, ... More
Force and torque of a string on a pulleyJun 19 2017Every university introductory physics course considers the problem of Atwood's machine taking into account the mass of the pulley. In the usual treatment the tensions at the two ends of the string are offhandedly taken to act on the pulley and be responsible ... More
Weakly Einstein critical metrics of the volume functional on compact manifolds with boundaryApr 27 2018Sep 26 2018The goal of this paper is to study weakly Einstein critical metrics of the volume functional on a compact manifold $M$ with smooth boundary $\partial M$. Here, we will give the complete classification for an $n$-dimensional, $n=3$ or $4,$ weakly Einstein ... More