Results for "Ramon Ferreira de Jesus"

total 38628took 0.13s
Submillimeter - sized proximity effect in graphite and bismuthFeb 08 2019In this work, we probe the electrical properties of macroscopic graphite and bismuth in which the electrical current is injected via superconducting electrodes, few millimeters apart from each other. Results reveal the induction of a partial superconducting-like ... More
A method for the online construction of the set of states of a Markov Decision Process using Answer Set ProgrammingJun 05 2017Non-stationary domains, that change in unpredicted ways, are a challenge for agents searching for optimal policies in sequential decision-making problems. This paper presents a combination of Markov Decision Processes (MDP) with Answer Set Programming ... More
Answer Set Programming for Non-Stationary Markov Decision ProcessesMay 03 2017Non-stationary domains, where unforeseen changes happen, present a challenge for agents to find an optimal policy for a sequential decision making problem. This work investigates a solution to this problem that combines Markov Decision Processes (MDP) ... More
Profinite genus of fundamental groups of Sol and Nil 3-manifoldsNov 17 2018We prove that the profinite genus of the fundamental group $\pi_{1}(M)\cong(\mathbb{Z}\times\mathbb{Z})\rtimes_{A}\mathbb{Z}$ of a Sol 3-manifold $M$ is equal to the order of the class group of the field $\mathbb{Q}(\lambda)$, where $\lambda$ is an eigenvalue ... More
Self-Driving Cars: A SurveyJan 14 2019We survey research on self-driving cars published in the literature focusing on autonomous cars developed since the DARPA challenges, which are equipped with an autonomy system that can be categorized as SAE level 3 or higher. The architecture of the ... More
Openness for Anosov familiesSep 02 2017Nov 21 2017Anosov families were introduced by A. Fisher and P. Arnoux motivated by generalizing the notion of Anosov diffeomorphism defined on a compact Riemannian manifold. Roughly, an Anosov family is a two-sided sequence of diffeomorphisms (or non-stationary ... More
On to the continuity of the map square root of nonnegative isomorphisms in Hilbert spacesApr 10 2015Let H be a real (or complex) Hilbert space. Every nonnegative operator $L \in L(H)$ admits a unique nonnegative square root $R \in L(H)$, i.e., a nonnegative operator $R \in L(H)$ such that $R^{2}= L$. Let $GL^{+}_{S}(H)$ be the set of nonnegative isomorphisms ... More
Local Stable and Unstable Manifolds for Anosov FamiliesSep 02 2017Sep 20 2017Anosov families were introduced by A. Fisher and P. Arnoux motivated by generalizing the notion of Anosov diffeomorphism defined on a compact Riemannian manifold. In addition to presenting several properties and examples of Anosov families, in this paper ... More
Structural stability and characterization of Anosov familiesSep 02 2017Mar 27 2018Anosov families are non-stationary dynamical systems with hyperbolic behavior. Non-trivial examples of Anosov families will be given in this paper. Non-stationary dynamical systems are classified by uniform topological conjugacy. We show the existence ... More
Structural stability and a characterization of Anosov familiesSep 02 2017Mar 01 2019Anosov families are non-stationary dynamical systems with hyperbolic behavior. Non-trivial examples of Anosov families will be given in this paper. We show the existence of invariant manifolds, the structrural stability and a characterization for a certain ... More
On the Continuity of the Topological Entropy of Non-autonomous Dynamical SystemsSep 03 2017Let $M$ be a compact Riemannian manifold. The set $\text{F}^{r}(M)$ consisting of sequences $(f_{i})_{i\in\mathbb{Z}}$ of $C^{r}$-diffeomorphisms on $M$ can be endowed with the compact topology or with the strong topology. A notion of topological entropy ... More
Evolution of Ideas: A Novel Memetic Algorithm Based on Semantic NetworksJan 12 2012Jan 17 2012This paper presents a new type of evolutionary algorithm (EA) based on the concept of "meme", where the individuals forming the population are represented by semantic networks and the fitness measure is defined as a function of the represented knowledge. ... More
Sums of Powers of Fibonacci and Lucas Polynomials in terms of FibopolynomialsJun 29 2012Mar 06 2013We study sums of powers of Fibonacci and Lucas polynomials of the form $% \sum_{n=0}^{q}F_{tsn}^{k}(x) $ and $\sum_{n=0}^{q}L_{tsn}^{k}% (x) $, where $s,t,k$ are given natural numbers, together with the corresponding alternating sums $\sum_{n=0}^{q}(-1) ... More
Algebraic Unimodular CountingApr 30 2001We study algebraic algorithms for expressing the number of non-negative integer solutions to a unimodular system of linear equations as a function of the right hand side. Our methods include Todd classes of toric varieties via Gr\"obner bases, and rational ... More
Modeling of a heat equation with a Dirac densityJun 26 2015Sep 23 2015We consider a linear hybrid system composed by two rods connected by a thin wall of length 2{\epsilon} and density 1/2{\epsilon}. By passing to a limit, we obtain a system describing heat flow of two rods connected by a singular point whose dynamics are ... More
A Sampling Kaczmarz-Motzkin Algorithm for Linear FeasibilityMay 04 2016Feb 28 2017We combine two iterative algorithms for solving large-scale systems of linear inequalities, the relaxation method of Agmon, Motzkin et al. and the randomized Kaczmarz method. In doing so, we obtain a family of algorithms that generalize and extend both ... More
The Minimum Euclidean-Norm Point on a Convex Polytope: Wolfe's Combinatorial Algorithm is ExponentialOct 06 2017Nov 03 2017The complexity of Philip Wolfe's method for the minimum Euclidean-norm point problem over a convex polytope has remained unknown since he proposed the method in 1974. The method is important because it is used as a subroutine for one of the most practical ... More
Fermions in odd space-time dimensions: back to basicsFeb 09 2005It is a well known feature of odd space-time dimensions $d$ that there exist two inequivalent fundamental representations $A$ and $B$ of the Dirac gamma matrices. Moreover, the parity transformation swaps the fermion fields living in $A$ and $B$. As a ... More
Focal set of curves in the Minkowski space near lightlike pointsJul 28 2015Aug 27 2015We study the geometry of curves in the Minkowski space and in the de Sitter space, specially at points where the tangent direction is lightlike (i.e. has length zero) called lightlike points of the curve. We define the focal sets of these curves and study ... More
On Chubanov's method for Linear ProgrammingApr 10 2012We discuss the method recently proposed by S. Chubanov for the linear feasibility problem. We present new, concise proofs and interpretations of some of his results. We then show how our proofs can be used to find strongly polynomial time algorithms for ... More
Not all simplicial polytopes are weakly vertex-decomposableMar 08 2012In 1980 Provan and Billera defined the notion of weak $k$-decomposability for pure simplicial complexes. They showed the diameter of a weakly $k$-decomposable simplicial complex $\Delta$ is bounded above by a polynomial function of the number of $k$-faces ... More
Electron and recoil ion momentum imaging with a magneto-optically trapped targetNov 04 2014A reaction microscope (ReMi) has been combined with a magneto-optical trap (MOT) for the kinematically complete investigation of atomic break-up processes. With the novel MOTReMi apparatus, the momentum vectors of the fragments of laser-cooled and state-prepared ... More
Grow-up for a quasilinear heat equation with a localized reactionJan 29 2018We study the behaviour of global solutions to the quasilinear heat equation with a reaction localized $$ u_t=(u^m)_{xx}+a(x) u^p, $$ $m, p>0$ and $a(x)$ being the characteristic function of an interval. we prove that there exists $p_0=\max\{1,\frac{m+1}2\}$ ... More
Theory of Multipole Solutions to the Sourceless Grad-Shafranov Equation in Plasma PhysicsAug 10 2018The rules to write out any one of the linearly independent functions belonging to the infinite set of those in polynomial form that satisfy the sourceless Grad-Shafranov equation as stated in the toroidal-polar coordinate system are established. It is ... More
The generalized Pareto process; with a view towards application and simulationMar 12 2012Oct 16 2014In extreme value statistics, the peaks-over-threshold method is widely used. The method is based on the generalized Pareto distribution characterizing probabilities of exceedances over high thresholds in $\mathbb {R}^d$. We present a generalization of ... More
On the block maxima method in extreme value theory: PWM estimatorsOct 11 2013Dec 30 2014In extreme value theory, there are two fundamental approaches, both widely used: the block maxima (BM) method and the peaks-over-threshold (POT) method. Whereas much theoretical research has gone into the POT method, the BM method has not been studied ... More
Grow-up for a quasilinear heat equation with a localized reaction in higher dimensionsJan 29 2018We study the behaviour of nonnegative solutions to the quasilinear heat equation with a reaction localized in a ball $$ u_t=\Delta u^m+a(x)u^p, $$ for $m>0$, $0<p\le\max\{1,m\}$, $a(x)=\mathds{1}_{B_L}(x)$, $0<L<\infty$ and $N\ge2$. We study when solutions, ... More
Solution to the Grad-Shafranov Boundary Value Problem for a Thermonuclear Plasma contained in a Toroidal Vase With a Conducting Wall under the Assumption of Constant Sources to the Equilibrium in Flux SpaceSep 05 2018A method is proposed to solve the Grad-Shafranov partial differential equation for the poloidal flux function associated with the equilibrium of a plasma magnetically confined in an axisymmetric torus under the assumption that the sources to the equilibrium ... More
Forecasting day-ahead electricity prices in Europe: the importance of considering market integrationAug 01 2017Dec 07 2017Motivated by the increasing integration among electricity markets, in this paper we propose two different methods to incorporate market integration in electricity price forecasting and to improve the predictive performance. First, we propose a deep neural ... More
A semantic network-based evolutionary algorithm for computational creativityApr 30 2014Jul 14 2014We introduce a novel evolutionary algorithm (EA) with a semantic network-based representation. For enabling this, we establish new formulations of EA variation operators, crossover and mutation, that we adapt to work on semantic networks. The algorithm ... More
Direct measurement of the two-point function in quantum fieldsJun 29 2018We analyze fast interaction cycles in bipartite quantum systems, showing that the statistics in one of the parties (the detector) can be used to determine the two-point correlator of the observable which mediates the coupling in the other (the target). ... More
Sub-Diffractive Band-Edge Solitons in Bose-Einstein Condensates in Periodic PotentialsOct 18 2005A new type of matter wave diffraction management is presented that leads to sub-diffractive soliton-like structures. The proposed management technique uses two counter-moving, identical periodic potentials (e.g. optical lattices). For suitable lattice ... More
Incremental Map Generation by Low Cost Robots Based on Possibility/Necessity GridsFeb 06 2013In this paper we present some results obtained with a troupe of low-cost robots designed to cooperatively explore and adquire the map of unknown structured orthogonal environments. In order to improve the covering of the explored zone, the robots show ... More
Analysing the behaviour of robot teams through relational sequential pattern miningOct 29 2010This report outlines the use of a relational representation in a Multi-Agent domain to model the behaviour of the whole system. A desired property in this systems is the ability of the team members to work together to achieve a common goal in a cooperative ... More
Robust end-to-end deep audiovisual speech recognitionNov 21 2016Speech is one of the most effective ways of communication among humans. Even though audio is the most common way of transmitting speech, very important information can be found in other modalities, such as vision. Vision is particularly useful when the ... More
Thermalization of particle detectors: The Unruh effect and its reverseJul 18 2016Dec 31 2016We study the Anti-Unruh effect in general stationary scenarios. We find that, for accelerated trajectories, a particle detector coupled to a KMS state of a quantum field can cool down (click less often) as the KMS temperature increases. Remarkably, this ... More
Automated Generation of Cross-Domain Analogies via Evolutionary ComputationApr 11 2012Analogy plays an important role in creativity, and is extensively used in science as well as art. In this paper we introduce a technique for the automated generation of cross-domain analogies based on a novel evolutionary algorithm (EA). Unlike existing ... More
Audiovisual Analytics Vocabulary and Ontology (AAVO): initial core and example expansionOct 27 2017Visual Analytics might be defined as data mining assisted by interactive visual interfaces. The field has been receiving prominent consideration by researchers, developers and the industry. The literature, however, is complex because it involves multiple ... More
QCD Corrections to QED Vacuum PolarizationJul 27 2007Apr 30 2008We compute QCD corrections to QED calculations for vacuum polarization in background magnetic fields. Formally, the diagram for virtual $e\bar{e}$ loops is identical to the one for virtual $q\bar{q}$ loops. However due to confinement, or to the growth ... More
The Impact of Redshift on Galaxy Morphometric Classification: case studies for SDSS, DES, LSST and HST with MorfometrykaJul 10 2017Dec 01 2018We have carried a detailed analysis on the impact of cosmological redshift in the non-parametric approach to automated galaxy morphology classification. We artificially redshifted each galaxy from the EFIGI 4458 sample (re-centred at $z \sim 0$) simulating ... More
Effect of Pions in Cosmic RaysApr 30 2008The effects of pions for vacuum polarization in background magnetic fields are considered. The effects of quark condensates is also briefly addresses. Although these effects are out of the measurement accuracy of laboratory experiments they may be relevant ... More
On maximum likelihood estimation of the extreme value indexJul 05 2004We prove asymptotic normality of the so-called maximum likelihood estimator of the extreme value index.
Pioneer anomaly? Gravitational pull due to the Kuiper beltMar 16 2005Jan 09 2006In this work we study the gravitational influence of the material extending from Uranus orbit to the Kuiper belt and beyond on objects moving within these regions. We conclude that a density distribution given by $\rho(r)=\frac{1}{r}$ (for $r\geq 20 UA$) ... More
Invariants of stable maps from the 3-sphere to the Euclidean 3-spaceJul 16 2018In the present work, we study the decompositions of codimension-one transitions that alter the singular set the of stable maps of $S^3$ into $\mathbb{R}^3,$ the topological behaviour of the singular set and the singularities in the branch set that involves ... More
The discrete yet ubiquitous theorems of Carathéodory, Helly, Sperner, Tucker, and TverbergJun 16 2017Oct 08 2018We discuss five discrete results: the lemmas of Sperner and Tucker from combinatorial topology and the theorems of Carath\'eodory, Helly, and Tverberg from combinatorial geometry. We explore their connections and emphasize their broad impact in application ... More
Parametric Polyhedra with at least $k$ Lattice Points: Their Semigroup Structure and the k-Frobenius ProblemSep 18 2014Jul 24 2015Given an integral $d \times n$ matrix $A$, the well-studied affine semigroup $\mbox{ Sg} (A)=\{ b : Ax=b, \ x \in {\mathbb Z}^n, x \geq 0\}$ can be stratified by the number of lattice points inside the parametric polyhedra $P_A(b)=\{x: Ax=b, x\geq0\}$. ... More
On Augmentation Algorithms for Linear and Integer-Linear Programming: From Edmonds-Karp to Bland and BeyondAug 15 2014Jan 15 2015Motivated by Bland's linear-programming generalization of the renowned Edmonds-Karp efficient refinement of the Ford-Fulkerson maximum-flow algorithm, we discuss three closely-related natural augmentation rules for linear and integer-linear optimization. ... More
Computation with Polynomial Equations and Inequalities arising in Combinatorial OptimizationSep 04 2009The purpose of this note is to survey a methodology to solve systems of polynomial equations and inequalities. The techniques we discuss use the algebra of multivariate polynomials with coefficients over a field to create large-scale linear algebra or ... More
Universality of the contact process with random dilutionJan 05 2011We present quasi-stationary simulations of the two-dimensional contact process with quenched disorder included through the random dilution of a fraction of the lattice sites (these sites are not susceptible to infection). Our results strongly indicate ... More
The cohomology ring of certain families of periodic virtually cyclic groupsMar 04 2016Let G be a virtually cyclic of the form (Z_a x Z_b) x Z or [Z_a x (Z b x Q_{2^i})] x Z. We compute the integral cohomology ring of G, and then obtain the periodicity of the Farell cohomology of these groups.
Complete classification of Minkowski vacua in generalised flux modelsNov 15 2009Nov 18 2009We present a complete and systematic analysis of the Minkowski extrema of the N=1, D=4 Supergravity potential obtained from type II orientifold models that are T-duality invariant, in the presence of generalised fluxes. Based on our previous work on algebras ... More
Flux moduli stabilisation, Supergravity algebras and no-go theoremsJul 31 2009Jan 20 2010We perform a complete classification of the flux-induced 12d algebras compatible with the set of N=1 type II orientifold models that are T-duality invariant, and allowed by the symmetries of the T^6/(Z_2 x Z_2) isotropic orbifold. The classification is ... More
$H_q-$semiclassical orthogonal polynomials via polynomial mappingsDec 18 2017In this work we study orthogonal polynomials via polynomial mappings in the framework of the $H_q-$semiclassical class. We consider two monic orthogonal polynomial sequences $\{p_n (x)\}_{n\geq0}$ and $\{q_n(x)\}_{n\geq0}$ such that $$ p_{kn}(x)=q_n(x^k)\;,\quad ... More
The Gromov Norm of the Product of Two SurfacesJul 12 2004May 09 2008We make an estimation of the value of the Gromov norm of the Cartesian product of two surfaces. Our method uses a connection between these norms and the minimal size of triangulations of the products of two polygons. This allows us to prove that the Gromov ... More
A simple derivation of the Lindblad equationOct 10 2011Oct 17 2012We present a derivation of the Lindblad equation - an important tool for the treatment of non-unitary evolutions - that is accessible to undergraduate students in physics or mathematics with a basic background on quantum mechanics. We consider a specific ... More
Estimate of the validity interval for the Antimaximum Principle and application to a non-cooperative systemJan 11 2019We are concerned with the sign of the solutions of non-cooperative systems when the parameter varies near a principal eigenvalue of the system. With this aim we give precise estimates of the validity interval for the Antimaximum Principle for an equation ... More
A Generating Function for all Semi-Magic Squares and the Volume of the Birkhoff PolytopeJan 30 2007Oct 09 2008We present a multivariate generating function for all n x n nonnegative integral matrices with all row and column sums equal to a positive integer t, the so called semi-magic squares. As a consequence we obtain formulas for all coefficients of the Ehrhart ... More
Identification of redundant and synergetic circuits in triplets of electrophysiological dataApr 27 2014Sep 10 2015Neural systems are comprised of interacting units, and relevant information regarding their function or malfunction can be inferred by analyzing the statistical dependencies between the activity of each unit. Whilst correlations and mutual information ... More
Coherent blue emission induced by a combination of diode and femtosecond lasersMay 01 2016We report the investigation of a collimated blue light generated in rubidium vapor due to the combined action of an ultrashort pulse train and a cw diode laser. Each step of the two-photon transition 5S - 5P$_{3/2}$ - 5D is excited by one of the lasers, ... More
Elliptical orbits in the phase-space quantizationMay 25 2016Jul 14 2016The energy levels of hydrogen-like atoms are obtained from the phase-space quantization, one of the pillars of the old quantum theory, by three different methods - (i) direct integration, (ii) Sommerfeld's original method, and (iii) complex integration. ... More
Plasma Diagnostic and Performance of a Permanent Magnet Hall ThrusterOct 20 2004Electric propulsion is now a sucessfull method for primary propulsion of deep space long duration missions and for geosyncronous satellite attitude control. Closed Drift Plasma Thruster, so called Hall Thruster or SPT (stationary plasma thruster) were ... More
Probing QCD Corrections to QED Effects Through Optical Experiments in VacuumSep 29 2006Jul 03 2007A numerical estimative error of the magnitude of the vacuum polarization effect due to electron-positron by a factor of $10^3$ in [PRL97(2006)100403; 269901(E)] invalidates the study carried in this work in its present context.
Reconstructing the invisible with matrix elementsDec 08 2017Nov 01 2018We propose a fully flexible method to perform an hypothesis test between signal and background based on the Matrix Element Method in the presence of multiple invisible particles. The proposed method performs a mapping of the measured final state onto ... More
Fast and Extensible Online Multivariate Kernel Density EstimationJun 08 2016We present xokde++, a state-of-the-art online kernel density estimation approach that maintains Gaussian mixture models input data streams. The approach follows state-of-the-art work on online density estimation, but was redesigned with computational ... More
Quantum anomalous Hall effect in metal-bis(dithiolene), magnetic properties, doping and interfacing grapheneMay 30 2018The realization of the Quantum anomalous Hall effect (QAHE) in two dimensional (2D) metal organic frameworks (MOFs), (MC$_4$S$_4$)$_3$ with M = Mn, Fe, Co, Ru and Rh, has been investigated based on a combination of first-principles calculations and tight ... More
Higher Harmonics in Non-Linear Vacuum from QED Effects Without Low Mass Intermediate ParticlesJun 08 2006Jul 03 2007We show that in the presence of a slowly rotating strong transverse magnetic field there is an infinite spectrum of harmonic wave functions $A_n$ due to the first order QED correction (in $\alpha^2$) given by the Euler-Heisenberg Lagrangian. The frequency ... More
Providing theoretical learning guarantees to Deep Learning NetworksNov 28 2017Deep Learning (DL) is one of the most common subjects when Machine Learning and Data Science approaches are considered. There are clearly two movements related to DL: the first aggregates researchers in quest to outperform other algorithms from literature, ... More
Quark-Gluon tagging with Shower Deconstruction: Unearthing dark matter and Higgs couplingsJul 20 2016Feb 26 2017The separation of quark and gluon initiated jets can be an important way to improve the sensitivity in searches for new physics or in measurements of Higgs boson properties. We present a simplified version of the shower deconstruction approach as a novel ... More
Standard Model Higgs boson pair production in the $(b\bar{b})(b\bar{b})$ final stateApr 28 2014Aug 13 2014Measuring the Higgs boson couplings as precisely as possible is one of the major goals of the High Luminosity LHC. We show that the $(b\bar{b})(b\bar{b})$ final state in Higgs boson pair production can be exploited in the boosted regime to give constraints ... More
Continuous and discontinuous absorbing-state phase transitions on Voronoi-Delaunay random latticesSep 17 2015Dec 18 2015We study absorbing-state phase transitions in two-dimensional Voronoi-Delaunay (VD) random lattices with quenched coordination disorder. Quenched randomness usually changes the criticality and destroys discontinuous transitions in low-dimensional nonequilibrium ... More
Cosmic string configuration in a five dimensional Brans-Dicke theoryApr 12 2009We consider a scalar field interaction with a cosmic string configuration in a flat 3-brane. The origin of this field is given by a compactification mechanism in the context of a 5-dimensional Brans-Dicke theory. We use the Cosmic Microwave Background ... More
Low dimensional behavior in three-dimensional coupled map latticesSep 12 2006Jun 12 2007The analysis of one-, two-, and three-dimensional coupled map lattices is here developed under a statistical and dynamical perspective. We show that the three-dimensional CML exhibits low dimensional behavior with long range correlation and the power ... More
Quasi-stationary simulations of the directed percolation universality class in d = 3 dimensionsJan 05 2011Jan 07 2011We present quasi-stationary simulations of three-dimensional models with a single absorbing configuration, namely the contact process (CP), the susceptible-infected-susceptible (SIS) model and the contact replication process (CRP). The moment ratios of ... More
Cosmological bounds of sterile neutrinos in a $SU(3)_C\otimes SU(3)_L\otimes SU(3)_R\otimes U(1)_N$ model as dark matter candidatesSep 10 2015We study sterile neutrinos in an extension of the standard model, based on the gauge group $SU(3)_C\otimes SU(3)_L\otimes SU(3)_R\otimes U(1)_N$, and use this model to illustrate how to apply cosmological limits to thermalized particles that decouple ... More
Molecule survival in magnetized protostellar disk winds. II. Predicted H2O line profiles versus Herschel/HIFI observationsNov 12 2015We investigate whether the broad wings of H2O emission identified with Herschel towards low-mass Class 0 and Class 1 protostars may be consistent with an origin in a dusty MHD disk wind, and the constraints it would set on the underlying disk properties. ... More
Layertronic control of topological states in multilayer metal-organic frameworksMar 08 2019We investigate the layer localization control of two-dimensional states in multilayer metal-organic frameworks (MOFs). For finite stackings of {\Ni} MOFs, the weak van der Waals coupling between adjacent layers leads to a Fermi level dependent distribution ... More
Electrostatic analogy of the Jackiw-Rebbi zero energy stateDec 04 2017We present an analogy between the one dimensional Poisson equation in inhomogeneous media and the Dirac equation in one space dimension with a Lorentz scalar potential for zero energy. We illustrate how the zero energy state in the Jackiw-Rebbi model ... More
Zero-bias anomaly in a nanowire quantum dot coupled to superconductorsJul 05 2012Oct 16 2012We studied the low-energy states of spin-1/2 quantum dots defined in InAs/InP nanowires and coupled to aluminium superconducting leads. By varying the superconducting gap, \Delta, with a magnetic field, B, we investigated the transition from strong coupling, ... More
Design of a Full-Stokes Polarimeter for VLT/X-shooterJul 12 2012X-shooter is one of the most popular instruments at the VLT, offering instantaneous spectroscopy from 300 to 2500 nm. We present the design of a single polarimetric unit at the polarization-free Cassegrain focus that serves all three spectrograph arms ... More
Spin-resolved Andreev levels and parity crossings in hybrid superconductor-semiconductor nanostructuresFeb 11 2013Jan 23 2014The hybrid combination of superconductors and low-dimensional semiconductors offers a versatile ground for novel device concepts, such as sources of spin-entangled electrons, nanoscale superconducting magnetometers, or recently proposed qubits based on ... More
CBR with Commonsense Reasoning and Structure Mapping: An Application to MediationJul 30 2011Oct 12 2011Mediation is an important method in dispute resolution. We implement a case based reasoning approach to mediation integrating analogical and commonsense reasoning components that allow an artificial mediation agent to satisfy requirements expected from ... More
The Unruh effect without thermalityApr 02 2018We show that uniformly accelerated detectors can display genuinely thermal features even if the Kubo-Martin-Schwinger (KMS) condition fails to hold. These features include satisfying thermal detailed balance and having a Planckian response identical to ... More
Scaling of sub-gap excitations in a superconductor-semiconductor nanowire quantum dotSep 24 2016A quantum dot coupled to a superconducting contact provides a tunable artificial analogue of a magnetic atom in a superconductor, a paradigmatic quantum impurity problem. We realize such a system with an InAs semiconductor nanowire contacted by an Al-based ... More
Quantum Oscillators in the Canonical Coherent StatesMay 16 2002Nov 18 2002The main characteristics of the quantum oscillator coherent states including the two-particle Calogero interaction are investigated. We show that these Calogero coherent states are the eigenstates of the second-order differential annihilation operator ... More
On the Index of Constant Mean Curvature HypersurfacesJan 28 2009In 1968, Simons introduced the concept of index for hypersurfaces immersed into the Euclidean sphere S^{n+1}. Intuitively, the index measures the number of independent directions in which a given hypersurface fails to minimize area. The earliest results ... More
Magnon delocalization in ferromagnetic chains with long-range correlated disorderDec 14 2001We study one-magnon excitations in a random ferromagnetic Heisenberg chain with long-range correlations in the coupling constant distribution. By employing an exact diagonalization procedure, we compute the localization length of all one-magnon states ... More
Random Monomial IdealsJan 25 2017Jan 05 2018Inspired by the study of random graphs and simplicial complexes, and motivated by the need to understand average behavior of ideals, we propose and study probabilistic models of random monomial ideals. We prove theorems about the probability distributions, ... More
Electrical properties of in-plane-implanted graphite nanoribbonsJun 26 2018We studied the effect of low energy (30 keV) ionic implantation of Ga+ in the direction parallel to the graphene planes (perpendicular to c-axis) in oriented graphite ribbons with widths around 500 nm. Our experiments have reproducibly shown a reduction ... More
HST STIS UV Spectroscopic Observations of the Protoplanetary Nebula Hen3-1475Oct 01 2018We present UV spectra of the protoplanetary nebula (pPN) Hen3-1475 obtained with the Space Telescope Imaging Spectrograph (STIS) on board the Hubble Space Telescope (HST). Our deep, low-dispersion spectroscopy enables monochromatic imaging of Hen3-1475 ... More
Non-Gaussian signatures and collective effects in charge noise affecting a dynamically-decoupled qubitJul 09 2015Oct 20 2015The effects of a collection of classical two-level charge fluctuators on the coherence of a dynamically-decoupled qubit are studied. Distinct dynamics are found at different qubit working positions. Exact analytical formulae are derived at pure dephasing ... More
Sparse solutions of linear Diophantine equationsJan 31 2016Jan 06 2017We present structural results on solutions to the Diophantine system $A{\boldsymbol y} = {\boldsymbol b}$, ${\boldsymbol y} \in \mathbb Z^t_{\ge 0}$ with the smallest number of non-zero entries. Our tools are algebraic and number theoretic in nature and ... More
Short Rational Functions for Toric Algebra and ApplicationsJul 26 2003We encode the binomials belonging to the toric ideal $I_A$ associated with an integral $d \times n$ matrix $A$ using a short sum of rational functions as introduced by Barvinok \cite{bar,newbar}. Under the assumption that $d,n$ are fixed, this representation ... More
Application of p-adic analysis to time seriesDec 13 2013Time series defined by a p-adic pseudo-differential equation is investigated using the expansion of the time series over p-adic wavelets. Quadratic correlation function is computed. This correlation function shows a degree--like behavior and is locally ... More
Fundamental ingredients for the emergence of discontinuous phase transitions in the majority vote modelFeb 14 2018Discontinuous transitions have received considerable interest due to the uncovering that many phenomena such as catastrophic changes, epidemic outbreaks and synchronization present a behavior signed by abrupt (macroscopic) changes (instead of smooth ones) ... More
Expansion of hydrogen-poor knots in the born-again planetary nebulae A30 and A78Oct 14 2014We analyze the expansion of hydrogen-poor knots and filaments in the born-again planetary nebulae A30 and A78 based on Hubble Space Telescope (HST) images obtained almost 20 yr apart. The proper motion of these features generally increases with distance ... More
Realcompactness and spaces of vector-valued functionsOct 27 2000May 14 2001It is shown that the existence of a biseparating map between a large class of spaces of vector-valued continuous functions A(X,E) and A(Y,F) implies that some compactifications of X and Y are homeomorphic. In some cases, conditions are given to warrant ... More
Automatic continuity and weighted composition operators between spaces of vector-valued differentiable functionsDec 20 2000Jan 19 2001It is proved that every linear biseparating map between spaces of vector-valued differentiable functions is a weighted composition map. As a consequence, such a map is always continuous.
On the Lie structure of a prime associative superalgebraJul 11 2013In this paper some results on the Lie structure of prime superalgebras are discussed. We prove that, with the exception of some special cases, for a prime superalgebra, $A$, over a ring of scalars $\Phi$ with $1/2\in \Phi$, if $L$ is a Lie ideal of $A$ ... More
Easy Proofs of Some Borwein Algorithms for $π$Mar 07 2008In 1987 Jonathan and Peter Borwein, inspired by the works of Ramanujan, derived many efficient algorithms for computing $\pi$. We will see that by using only a formula of Gauss's and elementary algebra we are able to prove the correctness of two of them. ... More
The Einstein Cross: constraint on dark matter from stellar dynamics and gravitational lensingJul 25 2008Dec 24 2010[Abridged] We present two-dimensional line-of-sight stellar kinematics of the lens galaxy in the Einstein Cross, obtained with the GEMINI 8m telescope, using the GMOS integral-field spectrograph. The velocity map shows regular rotation up to ~100 km/s ... More