Results for "A. de la Torre"

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Understanding light quanta: The PhotonOct 22 2004Jul 28 2005An antisymmetric tensor, the photon tensor, is defined for the description of the photon as a massless relativistic particle. The photon can be visualized as an essentially two dimensional rotating object. The quantum mechanical description of a single ... More
The ubiquitous XP commutatorSep 23 2005Position and momentum of a particle can take any value in a continuous spectrum; these values are independent but their indeterminacies are correlated; momentum and position are mutually the generators of the transformations in each other. It is shown ... More
Understanding light quanta:Construction of the free electromagnetic fieldMar 02 2005Apr 15 2005The free electromagnetic field, solution of Maxwell's equations and carrier of energy, momentum and spin, is construed as an emergent collective property of an ensemble of photons, and with this, the consistency of an interpretation that considers that ... More
Understanding light quanta: First quantization of the free electromagnetic fieldOct 21 2004The quantization of the electromagnetic field in vacuum is presented without reference to lagrangean quantum field theory. The equal time commutators of the fields are calculated from basic principles. A physical discussion of the commutators suggest ... More
A one-dimensional lattice model for a quantum mechanical free particleMay 10 1999Two types of particles, A and B with their corresponding antiparticles, are defined in a one dimensional cyclic lattice with an odd number of sites. In each step of time evolution, each particle acts as a source for the polarization field of the other ... More
Relativity of representations in quantum mechanicsSep 25 2001Only the position representation is used in introductory quantum mechanics and the momentum representation is not usually presented until advanced undergraduate courses. To emphasize the relativity of the representations of the abstract formulation of ... More
Quantum Mechanics as a Classical Field TheoryMay 10 1999The formalism of quantum mechanics is presented in a way that its interpretation as a classical field theory is emphasized. Two coupled real fields are defined with given equations of motion. Densities and currents associated to the fields are found with ... More
Quantum mechanics in finite dimensional Hilbert spaceMay 24 2002The quantum mechanical formalism for position and momentum of a particle in a one dimensional cyclic lattice is constructively developed. Some mathematical features characteristic of the finite dimensional Hilbert space are compared with the infinite ... More
Quantum state reconstruction from dynamical systems theoryMar 16 2011Dec 27 2013When an informationally incomplete set of observables is considered there are several solutions to the quantum state reconstruction problem using von Neumann measurements. The set of solutions are known as Pauli partners, which are not easy to find even ... More
Quantum tomography meets dynamical systems and bifurcations theoryJan 07 2014A powerful tool for studying geometrical problems in Hilbert space is developed. In particular, we study the quantum pure state tomography problem in finite dimensions from the point of view of dynamical systems and bifurcations theory. First, we introduce ... More
Coherent states for free particlesApr 15 2010The coherent states are reviewed with particular application to the free particle system. The didactic advantages of the formalism is emphasized. Several interesting features, like the relation of the coherent states with the Galilei group and with the ... More
Reconstructing the distribution of haloes and mock galaxies below the resolution limit in cosmological simulationsDec 14 2012Jul 18 2013We present a method for populating dark matter simulations with haloes of mass below the resolution limit. It is based on stochastically sampling a field derived from the density field of the halo catalogue, using constraints from the conditional halo ... More
The Photon-Box Bohr-Einstein Debate DemithologizedOct 08 1999The legendary discussion between Einstein and Bohr concerning the photon box experiment is critically analyzed. It is shown that Einstein's argument is flawed and Bohr's reply is wrong.
Quantum diffusion on a cyclic one dimensional latticeApr 09 2003The quantum diffusion of a particle in an initially localized state on a cyclic lattice with N sites is studied. Diffusion and reconstruction time are calculated. Strong differences are found for even or odd number of sites and the limit N->infinit is ... More
Finite element discretization of non-linear diffusion equations with thermal fluctuationsOct 23 2014Feb 17 2015We present a finite element discretization of a non-linear diffusion equation used in the field of critical phenomena and, more recently, in the context of Dynamic Density Functional Theory. The discretized equation preserves the structure of the continuum ... More
Entanglement for all quantum statesFeb 15 2010It is shown that a state that is factorizable in the Hilbert space corresponding to some choice of degrees of freedom, becomes entangled for a different choice of degrees of freedom. Therefore, entanglement is not a special case but is ubiquitous in quantum ... More
Locus model for space-time fabric and quantum indeterminaciesMay 09 2017A simple locus model for the space-time fabric is presented and is compared with quantum foam and random walk models. The induced indeterminacies in momentum are calculated and it is shown that these space-time fabric indeterminacies are, in most cases, ... More
The position-momentum symmetry principleNov 11 2013It is shown that the Fourier transformation that relates position and momentum representations of quantum mechanics can be understood as a consequence of a symmetry principle that establishes the equivalence of being and becoming in the description of ... More
On position, momentum and their correlationAug 22 2013Position and momentum observables are considered and their correlation is studied for the simplest quantum system of a free particle moving in one dimension. The algebra and the eigenvalue problem for the correlation observable is presented and its possible ... More
On Randomness in Quantum MechanicsJul 19 2007The quantum mechanical probability densities are compared with the probability densities treated by the theory of random variables. The relevance of their difference for the interpretation of quantum mechanics is commented.
Do we finally understand Quantum Mechanics?May 02 2016Jun 28 2016The ontology emerging from quantum field theory and the results following from Bell's theorems allowed the development of an intuitive picture of the microscopic world described by quantum mechanics, that is, we can say that we understand this theory. ... More
Observables have no value: a no-go theorem for position and momentum observablesMar 30 2006Oct 09 2006A very simple illustration of the Bell-Kochen-Specker contradiction is presented using continuous observables in infinite dimensional Hilbert space. It is shown that the assumption of the \emph{existence} of putative values for position and momentum observables ... More
A quantum arrow of timeNov 09 2014It is shown that position-momentum correlation is never decreasing and therefore it is a good candidate as a quantum arrow of time devoid of shortcomings of other proposals.
The quantum field theory interpretation of quantum mechanicsMar 02 2015It is shown that adopting the \emph{Quantum Field} ---extended entity in space-time build by dynamic appearance propagation and annihilation of virtual particles--- as the primary ontology the astonishing features of quantum mechanics can be rendered ... More
Quantum stochastic processes in two dimensional space-timeMay 16 2015Oct 31 2015Several stochastic processes with virtual particles in two dimensional space-time are presented whose mean field equations coincide with Schr\"odinger, Dirac, Klein-Gordon and the quantum mechanic equation for a photon. These processes could be used to ... More
On the Benefits of Surrogate Lagrangians in Optimal Control and Planning AlgorithmsSep 12 2017This paper explores the relationship between numerical integrators and optimal control algorithms. Specifically, the performance of the differential dynamical programming (DDP) algorithm is examined when a variational integrator and a newly proposed surrogate ... More
Modelling non-linear redshift-space distortions in the galaxy clustering pattern: systematic errors on the growth rate parameterFeb 24 2012Jul 30 2012We investigate the ability of state-of-the-art redshift-space distortions models for the galaxy anisotropic two-point correlation function \xi(r_p, \pi), to recover precise and unbiased estimates of the linear growth rate of structure f, when applied ... More
Floquet Engineering in Quantum ChainsJan 21 2018We consider a one-dimensional interacting spinless fermion model, which displays the well-known Luttinger liquid (LL) to charge density wave (CDW) transition as a function of the ratio between the strength of the interaction, $U$, and the hopping, $J$. ... More
Floquet Engineering in Quantum ChainsJan 21 2018Mar 25 2018We consider a one-dimensional interacting spinless fermion model, which displays the well-known Luttinger liquid (LL) to charge density wave (CDW) transition as a function of the ratio between the strength of the interaction, $U$, and the hopping, $J$. ... More
Surrogate Lagrangians for Variational Integrators: High Order Convergence with Low Order SchemesSep 12 2017Variational integrators are momentum-preserving and symplectic numerical methods used to propagate the evolution of Hamiltonian systems. In this paper, we introduce a new class of variational integrators that achieve fourth-order convergence despite having ... More
Slow dynamics in a turbulent von Kármán swirling flowFeb 19 2007Jun 20 2007We present an experimental study of a turbulent von K\'arm\'an flow produced in a cylindrical container using two propellers. The mean flow is stationary up to $Re = 10^4$, where a bifurcation takes place. The new regime breaks some symmetries of the ... More
Supervised Descent Method for Solving Nonlinear Least Squares Problems in Computer VisionMay 03 2014Many computer vision problems (e.g., camera calibration, image alignment, structure from motion) are solved with nonlinear optimization methods. It is generally accepted that second order descent methods are the most robust, fast, and reliable approaches ... More
Resilient Coordination of Networked Multiagent Systems Based on Distributed State EmulatorsMar 16 2014This note studies resilient coordination of networked multiagent systems in the presence of misbehaving agents, i.e., agents that are subject to adversaries modeled as exogenous disturbances. Apart from the existing relevant literature that make specific ... More
On the Quasi-Exact Solvability of the Confluent Heun EquationJun 10 2014Oct 05 2014It is shown that the Confluent Heun Equation (CHEq) reduces for certain conditions of the parameters to a particular class of Quasi-Exactly Solvable models, associated with the Lie algebra $sl (2,{\mathbb R})$. As a consequence it is possible to find ... More
Changing shapes: adiabatic dynamics of composite solitary wavesNov 24 2004We discuss the solitary wave solutions of a particular two-component scalar field model in two-dimensional Minkowski space. These solitary waves involve one, two or four lumps of energy. The adiabatic motion of these composite non-linear non-dispersive ... More
Adiabatic motion of two-component BPS kinksJul 08 2002Oct 04 2002The low energy dynamics of degenerated BPS domain walls arising in a generalized Wess-Zumino model is described as geodesic motion in the space of these topological walls.
Jacobi Metric and Morse Theory of Dynamical SystemsDec 04 2002The generalization of the Maupertuis principle to second-order Variational Calculus is performed. The stability of the solutions of a natural dynamical system is thus analyzed via the extension of the Theorem of Jacobi. It is shown that the Morse Theory ... More
Supersymmetry versus Integrability in two-dimensional Classical MechanicsJul 14 2003Jul 25 2003Supersymmetric extensions of Hamilton-Jacobi separable Liouville mechanical systems with two degrees of freedom are defined. It is shown that supersymmetry can be implemented in this type of systems in two independent ways. The structure of the constants ... More
A generalized Holling type II model for the interaction between dextral-sinistral snails and Pareas snakesJul 06 2018Pareatic snakes possess outstanding asymmetry in the mandibular tooth number, which has probably been caused by its evolution to improve the feeding on the predominant dextral snails. Gene mutation can generate chiral inversion on the snail body. A sinistral ... More
On two-dimensional superpotentials: from classical Hamilton-Jacobi theory to 2D supersymmetric quantum mechanicsJan 09 2004May 04 2004Superpotentials in ${\cal N}=2$ supersymmetric classical mechanics are no more than the Hamilton characteristic function of the Hamilton-Jacobi theory for the associated purely bosonic dynamical system. Modulo a global sign, there are several superpotentials ... More
Kink manifolds in a three-component scalar field theoryJan 07 2004In this work we identify the manifold of solitary waves arising in a three-component scalar field model using the Bogomol'nyi arrangement of the energy functional. A rich structure of topological and non-topological kinks exists in the different sub-models ... More
Equivalence between Type I Liouville dynamical systems in the plane and the sphereOct 29 2018Separable Hamiltonian systems either in sphero-conical coordinates on a $S^2$ sphere or in elliptic coordinates on a ${\mathbb R}^2$ plane are described in an unified way. A back and forth route connecting these Liouville Type I separable systems is unveiled. ... More
Factorization of supersymmetric Hamiltonians in curvilinear coordinatesFeb 11 2012Planar supersymmetric quantum mechanical systems with separable spectral problem in curvilinear coordinates are analyzed in full generality. We explicitly construct the supersymmetric extension of the Euler/Pauli Hamiltonian describing the motion of a ... More
Quantum oscillations of self-dual Abrikosov-Nielsen-Olesen vorticesApr 18 2005Jun 13 2005The mass shift induced by one-loop quantum fluctuations on self-dual ANO vortices is computed using heat kernel/generalized zeta function regularization methods. The quantum masses of super-imposed multi-vortices with vorticity lower than five are given. ... More
Magnetic force microscopy investigation of arrays of nickel nanowires and nanotubesJun 26 2014The magnetic properties of arrays of nanowires (NWs) and nanotubes (NTs), 150 nm in diameter, electrodeposited inside nanoporous polycarbonate membranes are investigated. The comparison of the nanoscopic magnetic force microscopy (MFM) imaging and the ... More
Susy Cosmological ModelsJun 01 2001Jul 03 2001In this work we consider the action for a set of complex scalar supermultiplets interacting with the scale factor in the supersymmetric cosmological models. We show that the local conformal supersymmetry leads to a scalar field potential defined in terms ... More
Group-galaxy correlations in redshift space as a probe of the growth of structureFeb 17 2015Mar 22 2016We investigate the use of the cross-correlation between galaxies and galaxy groups to measure redshift-space distortions (RSD) and thus probe the growth rate of cosmological structure. This is compared to the classical approach based on using galaxy auto-correlation. ... More
One-loop fluctuations of semi-local self-dual vorticesOct 16 2007Jan 22 2008Mass shifts induced by one-loop fluctuations of semi-local self-dual vortices are computed. The procedure is based on canonical quantization and heat kernel/ zeta function regularization methods. The issue of the survival of the classical degeneracy in ... More
One loop corrections to the mass of self-dual semi-local planar topological solitonsJul 31 2007Nov 20 2007A formula is derived that allows the computation of one-loop mass shifts for self-dual semilocal topological solitons. These extended objects, which in three spatial dimensions are called semi-local strings, arise in a generalized Abelian Higgs model ... More
Elementary solutions of the quantum planar two center problemMar 17 2016Oct 02 2017The quantum problem of an electron moving in a plane under the field created by two Coulombian centers admits simple analytical solutions for some particular inter-center distances. These elementary eigenfunctions, akin to those found by Demkov for the ... More
Orbits in the problem of two fixed centers on the sphereMar 31 2017Oct 02 2017A trajectory isomorphism between the two Newtonian fixed center problem in the sphere and two associated planar two fixed center problems is constructed by performing two simultaneous gnomonic projections in $S^2$. This isomorphism converts the original ... More
Solitary Waves in Massive Nonlinear S^N-Sigma ModelsFeb 09 2010The solitary waves of massive (1+1)-dimensional nonlinear S^N-sigma models are unveiled. It is shown that the solitary waves in these systems are in one-to-one correspondence with the separatrix trajectories in the repulsive N-dimensional Neumann mechanical ... More
One-loop mass shift formula for kinks and self-dual vorticesOct 27 2005Nov 25 2005A formula is derived that allows us to compute one-loop mass shifts for kinks and self-dual Abrikosov-Nielsen-Olesen vortices. The procedure is based in canonical quantization and heat kernel/zeta function regularization methods.
A New Association of Post-T Tauri Stars Near The SunMay 30 2000May 31 2000Observing ROSAT sources in 20 x 25 deg centered at the high latitude active star ER Eri, we found evidences for a new young nearby association (~30Myr at~60pc), the Horologium Association (HorA), formed by at least 10 probable and 6 possible members, ... More
A charge density wave-like instability in a doped spin-orbit-assisted weak Mott insulatorJan 18 2017Layered perovskite iridates realize a rare class of Mott insulators that are predicted to be strongly spin-orbit coupled analogues of the parent state of cuprate high-temperature superconductors. Recent discoveries of pseudogap, magnetic multipolar ordered ... More
On the Supersymmetric Spectra of two Planar Integrable Quantum SystemsJul 25 2011Two planar supersymmetric quantum mechanical systems built around the quantum integrable Kepler/Coulomb and Euler/Coulomb problems are analyzed in depth. The supersymmetric spectra of both systems are unveiled, profiting from symmetry operators not related ... More
Rapid modelling of the redshift-space power spectrum multipoles for a masked density fieldNov 24 2015Sep 09 2016In this work we reformulate the forward modelling of the redshift-space power spectrum multipole moments for a masked density field, as encountered in galaxy redshift surveys. Exploiting the symmetries of the redshift-space correlation function, we provide ... More
Quantum corrections to the mass of self-dual vorticesJun 15 2004Sep 13 2004The mass shift induced by one-loop quantum fluctuations on self-dual ANO vortices is computed using heat kernel/generalized zeta function regularization methods.
From N=2 supersymmetric classical to quantum mechanics and back: the SUSY WKB approximationMar 29 2006Links between supersymmetric classical and quantum mechanics are explored. Diagrammatic representations for \hbar-expansions of norms of ground states are provided. The WKB spectra of supersymmetric non harmonic oscillators are found.
Two-Dimensional Supersymmetric Quantum Mechanics: Two Fixed Centers of ForceDec 21 2007The problem of building supersymmetry in the quantum mechanics of two Coulombian centers of force is analyzed. It is shown that there are essentially two ways of proceeding. The spectral problems of the SUSY (scalar) Hamiltonians are quite similar and ... More
The Extended R CrA Young AssociationMay 16 2001Observing ROSAT sources in an area covering ~30% of the Southern Hemisphere, including the R CrA Association, we found evidences that this nearby association may be much larger than previously thought. Although in the survey we found many young stars ... More
Elementary solutions of the quantum planar two center problemMar 17 2016The quantum problem of an electron moving in a plane under the field created by two Coulombian centers admits simple analytical solutions for some particular inter-center distances. These elementary eigenfunctions, akin to those found by Demkov for the ... More
Quantum magnetic flux lines, BPS vortex zero modes, and one-loop string tension shiftsMay 30 2016Sep 05 2016Spectral heat kernel/zeta function regularization procedures are employed in this paper to control the divergences arising from vacuum fluctuations of Bogomolnyi-Prasad-Sommerfield vortices in the Abelian Higgs model. Zero modes of vortex fluctuations ... More
New Southern GroupsMay 16 2001Since the eighties we have begun, in Brazil, a search for Post-T Tauri stars. Here we describe the main steps of this research that resulted in the discovery of the nearby TW Hya and Horologium associations. A very recent survey resulted in the detection ... More
Magnetic force microscopy study of the switching field distribution of low density arrays of single domain magnetic nanowiresApr 23 2013In the present work, we report on the in situ magnetic force microscopy (MFM) study of the magnetization reversal in two-dimensional arrays of ferromagnetic Ni80Fe20 and Co55Fe45 nanowires(NW) with different diameters (40, 50, 70 and 100 nm) deposited ... More
Interacting Dark Energy: Decay into FermionsFeb 08 2007A dark energy component is responsible for the present stage of acceleration of our universe. If no fine tuning is assumed on the dark energy potential then it will end up dominating the universe at late times and the universe will not stop this stage ... More
Dark Matter from the Inflaton FieldJan 30 2012We present a model where inflation and Dark Matter takes place via a single scalar field phi. Without introducing any new parameters we are able unify inflation and Dark Matter using a scalar field phi that accounts for inflation at an early epoch while ... More
The Fate of the Universe: Dark Energy Dilution?Jan 23 2007We study the possibility that dark energy decays in the future and the universe stops accelerating. The fact thatthe cosmological observations prefer an equation of state of dark energy smaller than -1 can be a signal that dark energy will decay in the ... More
Can Moduli Fields parametrize the Cosmological Constant?Oct 13 1999We study the cosmological evolution of string/M moduli fields T. We use T-duality to fix the potential and show that the superpotential W is a function of the duality invariant function j(T) only. If W is given as a finite polynomial of j then the moduli ... More
Interacting dark energy: generic cosmological evolution for two scalar fieldsMar 27 2007We study the cosmological evolution of two coupled scalar fields with an arbitrary interaction term V_T(\phi,\vp) in the presence of a barotropic fluid, which can be matter or radiation. The force between the barotropic fluid and the scalar fields is ... More
Phenomenological implications from moduli fields in stringsJan 12 1994Feb 03 1994We study some phenomenological consequences of having moduli fields with large vacuum expectation values (v.e.v.). The v.e.vs of the moduli are dynamically determined once supersymmetry is broken in 4D string theories. The study constraints the possible ... More
Quintessence Unification Models from Non-Abelian Gauge DynamicsNov 22 2001Oct 22 2002We show that the condensates of a non-abelian gauge group, unified with the standard model gauge groups, can parameterize the present day cosmological constant and play the role of quintessence. The models agree with SN1a and recent CMB analysis. These ... More
Unification Scale in String TheoryJan 12 1994Feb 03 1994We study the unification scale and gauge coupling constant in 4D string theory. We show that the fine structure constant is determined by the dimension of the hidden gauge group and only $SU(6)$ and $SO(9)$ are consistent with minimal string unification ... More
A Realistic Particle Physics Dark Energy ModelSep 22 2004We present a realistic dark energy model derived from particle physics. Our model has essentially no free parameters and has an equivalent fit to the observational data (CMB, SN1a and LSS) as LCDM and a better fit than the best effective $w(z)$ model. ... More
Model Independent Accelerating Universe and the Cosmological Coinc idence ProblemNov 05 1999We show that the evolution of the quintessence energy density $\Omega_Q$ is model independent in an accelerating universe. The accelerating behaviour has lasted at most 0.5 e-folds of expansion assuming a present day value of $\Omega_Q=2/3$. The generic ... More
Degenerate BPS Domain Walls: Classical and Quantum DynamicsNov 07 2003Dec 17 2003We discuss classical and quantum aspects of the dynamics of a family of domain walls arising in a generalized Wess-Zumino model. These domain walls can be embedded in ${\cal N}=1$ supergravity as exact solutions and are composed of two basic lumps.
On a Rapid Lithium Enrichment and Depletion of K Giant StarsMar 20 1997A model scenario has recently been introduced to explain the presence of very strong Li lines in the spectra of some low mass K giant stars (de la Reza et al. 1996). In this scenario all ordinary, Li poor, K giants become Li rich during a short time ($\sim ... More
Spin-orbit splitting of the Shockley surface state on Cu(111)Jan 25 2013We present angle-resolved photoemission data from Cu(111). Using a focused 6 eV continuous wave laser for photo-excitation, we achieve a high effective momentum resolution enabling the first detection of the Rashba spin splitting in the Shockley surface ... More
Search for associations containing young stars. III- Ages and Li abundancesSep 03 2009Our study is a follow-up of the SACY project, an extended survey in the Southern Hemisphere targeted to search for young nearby associations. Nine associations have either been newly identified, or had their member list better defined. These associations, ... More
SACY - a Search for Associations Containing Young starsJun 12 2003The scientific goal of the SACY (Search for Associations Containing Young-stars) was to identify possible associations of stars younger than the Pleiades Association among optical counterparts of the ROSAT X-ray bright sources. High-resolution spectra ... More
Visibly Pushdown Modular GamesAug 26 2014Games on recursive game graphs can be used to reason about the control flow of sequential programs with recursion. In games over recursive game graphs, the most natural notion of strategy is the modular strategy, i.e., a strategy that is local to a module ... More
Identical particles are indistinguishable but..Aug 22 2008It is shown that quantum systems of identical particles can be treated as if they were different when they are in well differentiated states. This simplifying assumption allows the consideration of quantum systems isolated from the rest of the universe ... More
Characterization of quantum correlations with local dimension constraints and its device-independent applicationsAug 15 2013Feb 02 2014The future progress of semi-device independent quantum information science depends crucially on our ability to bound the strength of the nonlocal correlations achievable with finite dimensional quantum resources. In this work, we characterize quantum ... More
Discriminative Optimization: Theory and Applications to Computer Vision ProblemsJul 13 2017Many computer vision problems are formulated as the optimization of a cost function. This approach faces two main challenges: (i) designing a cost function with a local optimum at an acceptable solution, and (ii) developing an efficient numerical method ... More
A Method to Search for Associations of Young StarsJun 12 2003In the SACY (Search for Associations Containing Young-stars) project we try to identify associations of stars younger than the Local Association among HIPPARCOS and/or TYCHO-2 stars later than G0 which are counterparts of the ROSAT X-ray bright sources. ... More
SACY - Present StatusJul 02 2002The scientific goal of the SACY (Search for Associations Containing Young-stars) project is to identify eventual associations of stars younger than the Local Association, spread among the optical counterparts of the ROSAT X-ray bright sources. High-resolution ... More
Can observed randomness be certified to be fully intrinsic?May 23 2013Randomness comes in two qualitatively different forms. Apparent randomness can result both from ignorance or lack of control of degrees of freedom in the system. In contrast, intrinsic randomness should not be ascribable to any such cause. While classical ... More
Feature and Region Selection for Visual LearningJul 20 2014Jan 19 2016Visual learning problems such as object classification and action recognition are typically approached using extensions of the popular bag-of-words (BoW) model. Despite its great success, it is unclear what visual features the BoW model is learning: Which ... More
The Great Austral Nearby Young AssociationMay 16 2001Observing ROSAT sources in an area covering $\sim$30% of the Southern Hemisphere, we found evidences for a great nearby association (GAYA), comprising the proposed associations of Horologium (HorA) and the eastern part of Tucana (TucA), formed by at least ... More
Distinguishing computable mixtures of quantum statesSep 07 2017In this article we extend results from our previous work [Bendersky, de la Torre, Senno, Figueira and Ac\'in, Phys. Rev. Lett. 116, 230406 (2016)] by providing a protocol to distinguish in finite time and with arbitrarily high success probability any ... More
Quantum fluctuations around low-dimensional topological defectsSep 11 2009In these Lectures a method is described to analyze the effect of quantum fluctuations on topological defect backgrounds up to the one-loop level. The method is based on the spectral heat kernel/zeta function regularization procedure, and it is first applied ... More
Search for Associations Containing Young stars (SACY): I. Sample & Searching MethodSep 09 2006We report results from a high-resolution optical spectroscopic survey aimed to search for nearby young associations and young stars among optical counterparts of ROSAT All-Sky Survey X-ray sources in the Southern Hemisphere. We selected 1953 late-type ... More
Fixed-Rank Representation for Unsupervised Visual LearningMar 09 2012Apr 17 2012Subspace clustering and feature extraction are two of the most commonly used unsupervised learning techniques in computer vision and pattern recognition. State-of-the-art techniques for subspace clustering make use of recent advances in sparsity and rank ... More
Model-Based Control Using Koopman OperatorsSep 05 2017This paper explores the application of Koopman operator theory to the control of robotic systems. The operator is introduced as a method to generate data-driven models that have utility for model-based control methods. We then motivate the use of the ... More
State determination: an iterative algorithmDec 24 2007An iterative algorithm for state determination is presented that uses as physical input the probability distributions for the eigenvalues of two or more observables in an unknown state $\Phi$. Starting form an arbitrary state $\Psi_{0}$, a succession ... 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
Modeling Spatial and Temporal Cues for Multi-label Facial Action Unit DetectionAug 02 2016Facial action units (AUs) are essential to decode human facial expressions. Researchers have focused on training AU detectors with a variety of features and classifiers. However, several issues remain. These are spatial representation, temporal modeling, ... More
Improving Transient Performance of Adaptive Control Architectures using Frequency-Limited System Error DynamicsSep 25 2013We develop an adaptive control architecture to achieve stabilization and command following of uncertain dynamical systems with improved transient performance. Our framework consists of a new reference system and an adaptive controller. The proposed reference ... More
A Deep Learning Interpretable Classifier for Diabetic Retinopathy Disease GradingDec 21 2017Deep neural network models have been proven to be very successful in image classification tasks, also for medical diagnosis, but their main concern is its lack of interpretability. They use to work as intuition machines with high statistical confidence ... More
Generalization of the second trace form of central simple algebras in characteristic twoOct 09 2004Let F be a field with characteristic two. We generalize the second trace form for central simple algebras with odd degree over F. We determine the second trace form and the Arf invariant and Clifford invariant for tensor products of central simple algebras. ... More