Results for "Ramon Ferreira de Jesus"

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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
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
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
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
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
A Sampling Kaczmarz-Motzkin Algorithm for Linear FeasibilityMay 04 2016Sep 08 2016We 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 master equation for the reduced open-system dynamics, including a Lindbladian description of finite-duration measurementFeb 17 2011Aug 18 2011We consider the problem of the measurement of a system occurring during a finite time interval, while environmentally-induced noise decreases the system-state coherence. We assume a Markovian measuring device and, therefore, use a Lindbladian description ... 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
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
Newtonian, Post Newtonian and Parameterized Post Newtonian limits of f(R, G) gravityNov 01 2013We discuss in detail the weak field limit of f(R,G) gravity taking into account analytic functions of the Ricci scalar R and the Gauss-Bonnet invariant G. Specifically, we develop, in metric formalism, the Newtonian, Post Newtonian and Parameterized Post ... 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
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
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 2016Nov 04 2016We 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
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
Proceedings of the Tenth Conference on Uncertainty in Artificial Intelligence (1994)Apr 13 2013This is the Proceedings of the Tenth Conference on Uncertainty in Artificial Intelligence, which was held in Seattle, WA, July 29-31, 1994
Top-down induction of clustering treesNov 21 2000An approach to clustering is presented that adapts the basic top-down induction of decision trees method towards clustering. To this aim, it employs the principles of instance based learning. The resulting methodology is implemented in the TIC (Top down ... 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
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
Severe Vesico-ureteral Reflux and Urine Sequestration: Mathematical Relations and Urodynamic ConsequencesFeb 03 2009Feb 03 2009Some simple mathematical formulae to calculate the volumes of proximal pyeloureteral reflexive systems are presented, and the results are compared to bladder capacity values. Using the results of the calculi, the author discusses possible implications ... More
On the Approximate Controllability of Stackelberg-Nash Strategies for Linear Heat Equations in $\mathbb{R}^N$ with PotentialsAug 05 2012In this paper we establish hierarchic control for the linear heat equation in $\re^N$ with potentials. Our strategy is inspired by the techniques developed by J.I. D\'iaz and J.-L. Lions \cite{DL}; however many new difficulties arise due to lack of compactness ... More
Error correction in short time steps during the application of quantum gatesSep 22 2011Jan 13 2016We propose a method for applying the quantum error-correction method for errors that occur during quantum gates. Using a perturbation treatment of the noise that allows us to separate it from the ideal evolution of the quantum gate, we demonstrate that ... 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.
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 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
Spectra and Symmetry in Nuclear PairingFeb 17 2007We apply the algebraic Bethe ansatz technique to the nuclear pairing problem with orbit dependent coupling constants and degenerate single particle energy levels. We find the exact energies and eigenstates. We show that for a given shell, there are degeneracies ... More
Quantitative Analysis of the Effective Functional Structure in Yeast GlycolysisSep 19 2010Jan 16 2011Yeast glycolysis is considered the prototype of dissipative biochemical oscillators. In cellular conditions, under sinusoidal source of glucose, the activity of glycolytic enzymes can display either periodic, quasiperiodic or chaotic behavior. In order ... 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
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
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
Capsule Networks for Protein Structure Classification and PredictionAug 22 2018Capsule Networks have great potential to tackle problems in structural biology because of their attention to hierarchical relationships. This paper describes the implementation and application of a Capsule Network architecture to the classification of ... 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
Dark matter cores in the Fornax and Sculptor dwarf galaxies: joining halo assembly and detailed star formation historiesSep 23 2013Jan 28 2014We combine the detailed Star Formation Histories of the Fornax and Sculptor dwarf Spheroidals with the Mass Assembly History of their dark matter (DM) halo progenitors to estimate if the energy deposited by Supernova type II (SNeII) is sufficient to create ... More
On firm specific characteristics of pharmaceutical generics and incentives to permanence under fuzzy conditionsSep 11 2012The aim of this paper is to develop a methodology that is useful for analysing from a microeconomic perspective the incentives to entry, permanence and exit in the market for pharmaceutical generics under fuzzy conditions. In an empirical application ... 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
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
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
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
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
Dispute Resolution Using Argumentation-Based MediationSep 15 2014Mediation is a process, in which both parties agree to resolve their dispute by negotiating over alternative solutions presented by a mediator. In order to construct such solutions, mediation brings more information and knowledge, and, if possible, resources ... More
A Symbolic Approach to Reasoning with Linguistic QuantifiersMar 13 2013This paper investigates the possibility of performing automated reasoning in probabilistic logic when probabilities are expressed by means of linguistic quantifiers. Each linguistic term is expressed as a prescribed interval of proportions. Then instead ... 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
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
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
How much time does a measurement take?Sep 21 2011Jan 04 2013We consider the problem of measurement using the Lindblad equation, which allows the introduction of time in the interaction between the measured system and the measurement apparatus. We use analytic results, valid for weak system-environment coupling, ... More
Weak values in collision theoryMar 19 2018Weak measurements have an increasing number of applications in contemporary quantum mechanics. They were originally described as a weak interaction that slightly entangled the translational degrees of freedom of a particle to its spin, yielding surprising ... More
Protecting a quantum state from environmental noise by an incompatible finite-time measurementJun 22 2011Jul 29 2011We show that measurements of finite duration performed on an open two-state system can protect the initial state from a phase-noisy environment, provided the measured observable does not commute with the perturbing interaction. When the measured observable ... More
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
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
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
Efficient finite-time measurements under thermal regimesSep 14 2013Jul 11 2014Contrary to conventional quantum mechanics, which treats measurement as instantaneous, here we explore a model for finite-time measurement. The main two-level system interacts with the measurement apparatus in a Markovian way described by the Lindblad ... 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
Role of Sterile Neutrino Warm Dark Matter in Rhenium and Tritium Beta DecaysSep 15 2011Sep 24 2012Sterile neutrinos with mass in the range of one to a few keV are important as extensions of the Standard Model of particle physics and are serious dark matter (DM) candidates. This DM mass scale (warm DM) is in agreement with both cosmological and galactic ... 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
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
Software for Exact Integration of Polynomials over PolyhedraJul 31 2011Apr 02 2012We are interested in the fast computation of the exact value of integrals of polynomial functions over convex polyhedra. We present speed ups and extensions of the algorithms presented in previous work. We present the new software implementation and provide ... More
Fair scans of the seesaw. Consequences for predictions on LFV processesOct 27 2010Usual analyses based on scans of the seesaw parameter-space can be biassed since they do not cover in a fair way the complete parameter-space. More precisely, we show that in the common "R-parametrization", many acceptable R-matrices, compatible with ... 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
Low-energy neutrinos at off-axis from a standard beta-beamMar 06 2007Sep 02 2007We discuss a scenario to extract up to 150 MeV neutrinos at a standard beta-beam facility using one and two detectors off-axis. In particular we show that the high-energy component of the neutrino fluxes can be subtracted through a specific combination ... 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
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
How to Integrate a Polynomial over a SimplexSep 11 2008Feb 13 2009This paper settles the computational complexity of the problem of integrating a polynomial function f over a rational simplex. We prove that the problem is NP-hard for arbitrary polynomials via a generalization of a theorem of Motzkin and Straus. On the ... 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
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
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
On wavelets to select the parametric form of a regression modelSep 28 2018Let Y be a response variable related with a set of explanatory variables and let f1, f2, ..., fk be a set of the parametric forms representing a set of candidate's model. Let f* be the true model among the set of k plausible models. We discuss in this ... More
Strict Very Fast Decision Tree: a memory conservative algorithm for data stream miningMay 16 2018May 17 2018Dealing with memory and time constraints are current challenges when learning from data streams with a massive amount of data. Many algorithms have been proposed to handle these difficulties, among them, the Very Fast Decision Tree (VFDT) algorithm. Although ... More
Thesaurus as a complex networkDec 22 2003A thesaurus is one, out of many, possible representations of term (or word) connectivity. The terms of a thesaurus are seen as the nodes and their relationship as the links of a directed graph. The directionality of the links retains all the thesaurus ... More
Sparse solutions of linear Diophantine equationsJan 31 2016Jul 08 2016We present structural results on solutions to the Diophantine system $A{\ve y} = {\ve b}$, ${\ve y} \in \ZZ^t_{\ge 0}$ with the smallest number of non-zero entries. Our tools are algebraic and number theoretic in nature and include Siegel's Lemma, generating ... More
Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar windNov 11 2016Binaries hosting a massive star and a non-accreting pulsar are powerful non-thermal emitters due to the interaction of the pulsar and the stellar wind. The winds of massive stars are thought to be inhomogeneous, which could have an impact on the non-thermal ... More
Terahertz-induced resistance oscillations in high mobility two-dimensional electron systemsApr 10 2016We report on a theoretical work on magnetotransport under terahertz radiation with high mobility two-dimensional electron systems. We focus on the interaction between the obtained radiation-induced magnetoresistance oscillations (RIRO) and the Shubnikov-de ... More
Evidence of radiation-driven Landau states in 2D electron systems: magnetoresistance oscillations phase shiftDec 21 2015Apr 01 2016We provide the ultimate explanation of one of the core features of microwave-induced magnetoresistance oscillations in high mobility two dimensional electron systems: the 1/4-cycle phase shift of minima. We start with the radiation-driven electron orbits ... More
Radiation-induced re-emission in a 2D electron systemNov 03 2014Recent experiments on re-emission of radiation and magnetotransport in photoexcited two-dimensional electron systems are theoretically analyzed. These experiments have concluded that there exists a strong correlation between the re-emitted radiation and ... More
Hypergeometric identities for 10 extended Ramanujan-type seriesApr 03 2011We prove, by the WZ-method, some hypergeometric identities which relate ten extended Ramanujan type series to simpler hypergeometric series. The identities we are going to prove are valid for all the values of a parameter $a$ when they are convergent. ... More
WZ-proofs of "divergent" Ramanujan-type seriesDec 13 2010Oct 14 2012We prove some "divergent" Ramanujan-type series for $1/\pi$ and $1/\pi^2$ applying a Barnes-integrals strategy of the WZ-method.
Multiple photoexcitation of two-dimensional electron systems: bichromatic magnetoresistance oscillations revisitedMay 18 2011We analyze theoretically magnetoresistance of high mobility two-dimensional electron systems being illuminated by multiple radiation sources. In particular, we study the influence on the striking effect of microwave-induced resistance oscillations. We ... More
Examples and counterexamples of type I isometric shiftsMar 29 2007Jul 18 2007We provide examples of nonseparable spaces $X$ for which C(X) admits an isometric shift of type I, which solves in the negative a problem proposed by Gutek {\em et al.} (J. Funct. Anal. {\bf 101} (1991), 97-119). We also give two independent methods for ... 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
Giant off-resonance resistance spike related phenomena in irradiated ultraclean two-dimensional electron systemsMar 06 2012We report on theoretical studies of a recently discovered strong radiation-induced magnetoresistance spike obtained in ultraclean two-dimensional electron systems at low temperatures. The most striking feature of this spike is that it shows up on the ... More
Plasmon phenomena as origin of DC-current induced resistivity oscillations in two-dimensional electron systemsNov 06 2007We analyze theoretically the oscillations that the magnetoresistivity of two-dimensional electron systems present when a high intensity direct current is applied. In the model presented here we suggest that a plasma wave is excited in the system producing ... 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
Hall magnetoresistivity response under Microwave excitation revisitedJun 05 2007We theoretically analyzed the microwave-induced modification of the Hall magnetoresistivity in high mobility two-dimensional electron systems. These systems present diagonal magnetoresistivity oscillations and zero-resistance states when are subjected ... More
On WZ-pairs which prove Ramanujan seriesApr 02 2009Jul 26 2010The known WZ-proofs for Ramanujan-type series related to $1/\pi$ gave us the insight to develop a new proof strategy based on the WZ-method. Using this approach we are able to find more generalizations and discover first WZ-proofs for certain series of ... More
Reconstructing warm inflationJan 16 2018Jan 22 2018The reconstruction of a warm inflationary universe model from the scalar spectral index $n_S(N)$ and the tensor to scalar ratio $r(N)$ as a function of the number of e-folds $N$ is studied. Under a general formalism we find the effective potential and ... More
The generalized second law of thermodynamics for the interacting in $f(T)$ gravityJan 31 2014We study the validity of the generalized second law (GSL) of gravitational thermodynamics in a non-flat FRW universe containing the interacting in $f(T)$ gravity. We consider that the boundary of the universe to be confined by the dynamical apparent horizon ... 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
Effect of frequency and temperature on microwave-induced magnetoresistance oscillations in two-dimensional electron systemsAug 11 2008Experimental results on microwave-induced magnetoresistance oscillation in two-dimensional electron systems show a similar behavior of these systems regarding temperature and microwave frequency. It is found that these oscillations tend to quench when ... More
Anharmonic behavior in Microwave-driven resistivity oscillations in Hall barsJun 10 2007We analyzed the magnetoresistivity of a two-dimensional electron system excited by microwave radiation in a regime of high intensities and low frequencies. In such a regime, recent experiments show that different features appear in the magnetoresistivity ... More