Results for "J. Perez-Romero"

total 193518took 0.28s
Coherent states on the Grassmannian $U(4)/U(2)^2$: Oscillator realization and bilayer fractional quantum Hall systemsDec 11 2013Feb 04 2014Bilayer quantum Hall (BLQH) systems, which underlie a $U(4)$ symmetry, display unique quantum coherence effects. We study coherent states (CS) on the complex Grassmannian $\mathbb G_2^4=U(4)/U(2)^2$, orthonormal basis, $U(4)$ generators and their matrix ... More
Some properties of Grassmannian $U(4)/U(2)^2$ coherent states and an entropic conjectureJun 04 2015Nov 23 2015We analyze mathematical and physical properties of a previously introduced [J. Phys. A47, 115302 (2014)] family of $U(4)$ coherent states (CS). They constitute a matrix version of standard spin $U(2)$ CS when we add an extra (pseudospin) dichotomous degree ... More
On the oscillator realization of conformal U(2,2) quantum particles and their particle-hole coherent statesMay 26 2014We revise the unireps. of $U(2,2)$ describing conformal particles with continuous mass spectrum from a many-body perspective, which shows massive conformal particles as compounds of two correlated massless particles. The statistics of the compound (boson/fermion) ... More
High energy protons from PKS 1333-33Nov 24 1998In this letter we give an account of the possible acceleration of protons in the outer radio lobes of the active galaxy PKS 1333-33. We also make estimates of the arrival energy spectrum.
An Iterative Parallel Algorithm for Computing Geodesic Distances on Triangular MeshesOct 18 2018The computation of geodesic distances is an important research topic in Geometry Processing and 3D Shape Analysis as it is a basic component of many methods used in these areas. For this reason, different approaches have been proposed to compute geodesic ... More
Design and Experimental Validation of a Software-Defined Radio Access Network Testbed with Slicing SupportMay 14 2019Network slicing is a fundamental feature of 5G systems to partition a single network into a number of segregated logical networks, each optimized for a particular type of service, or dedicated to a particular customer or application. The realization of ... More
The order parameter-entropy relation in some universal classes: experimental evidenceJan 30 2003The asymptotic behaviour near phase transitions can be suitably characterized by the scaling of $\Delta s/Q^2$ with $\epsilon=1-T/T_c$, where $\Delta s$ is the excess entropy and $Q$ is the order parameter. As $\Delta s$ is obtained by integration of ... More
Axiomatic Foundations of Nonrelativistic Quantum Mechanics: A Realistic ApproachOct 19 1995A realistic axiomatic formulation of nonrelativistic quantum mechanics for a single microsystem with spin is presented, from which the most important theorems of the theory can be deduced. In comparison with previous formulations, the formal aspect has ... More
Coherent States of Accelerated Relativistic Quantum Particles, Vacuum Radiation and the Spontaneous Breakdown of the Conformal SU(2,2) SymmetryDec 21 2010Aug 10 2011We give a quantum mechanical description of accelerated relativistic particles in the framework of Coherent States (CS) of the (3+1)-dimensional conformal group SU(2,2), with the role of accelerations played by special conformal transformations and with ... More
Representation of quantum field theory in an extended spin space and fermion mass hierarchyAug 18 2014We consider a matrix space based on the spin degree of freedom, describing both a Hilbert state space, and its corresponding symmetry operators. Under the requirement that the Lorentz symmetry be kept, at given dimension, scalar symmetries, and their ... More
Particles within extended-spin space: Lagrangian connectionDec 16 2015A spin-space extension is reviewed, which provides information on the standard model. Its defining feature is a common matrix space that describes symmetries and representations, and leads to limits on these, for given dimension. The model provides additional ... More
Accretion disks around black holes in modified strong gravityDec 11 2012Stellar-mass black holes offer what is perhaps the best scenario to test theories of gravity in the strong-field regime. In particular, f(R) theories, which have been widely discuss in a cosmological context, can be constrained through realistic astrophysical ... More
Hilbert space and ground state structure of bilayer quantum Hall systems at $ν=2/λ$Mar 15 2017Jun 14 2017We analyze the Hilbert space and ground state structure of bilayer quantum Hall (BLQH) systems at fractional filling factors $\nu=2/\lambda$ ($\lambda$ odd) and we also study the large $SU(4)$ isospin-$\lambda$ limit. The model Hamiltonian is an adaptation ... More
On the First eigenvalue of the Laplace operator for Compact Spacelike submanifolds in Lorentz-Minkowski Spacetime $\mathbb{L}^{m}$Dec 04 2018By means of a family of counter-examples, it is shown that the Reilly upper bound for the first eigenvalue of the Laplace operator for a compact submanifold in Euclidean space does not work for $n$-dimensional compact spacelike submanifolds of Lorentz-Minkowski ... More
On spacelike surfaces in 4-dimensional Lorentz-Minkowski spacetime through a lightconeFeb 21 2012On any spacelike surface in a lightcone of four dimensional Lorentz-Minkowski space a distinguished smooth function is considered. It is shown how both extrinsic and intrinsic geometry of such a surface is codified by this function. The existence of a ... More
Dirac equation in non-Riemannian geometriesOct 05 2012Oct 15 2012We present the Dirac equation in a geometry with torsion and non-metricity balancing generality and simplicity as much as possible. In doing so, we use the vielbein formalism and the Clifford algebra. We also use an index-free formalism which allows us ... More
Generalized Fredholm properties for invariant pseudodifferential operatorsJan 24 2011Apr 12 2011We define classes of pseudodifferential operators on $G$-bundles with compact base and give a generalized $L^2$ Fredholm theory for invariant operators in these classes in terms of von Neumann's $G$-dimension. We combine this formalism with a generalized ... More
Addressing mathematical inconsistency: Cantor and Godel refutedFeb 24 2010This article critically reappraises arguments in support of Cantor's theory of transfinite numbers. The following results are reported: i) Cantor's proofs of nondenumerability are refuted by analyzing the logical inconsistencies in implementation of the ... More
On the First eigenvalue of the Laplace operator for Compact Spacelike submanifolds in Lorentz-Minkowski Spacetime $\mathbb{L}^{m}$Dec 04 2018Feb 11 2019By means of a family of counter-examples, it is shown that the Reilly upper bound for the first eigenvalue of the Laplace operator for a compact submanifold in Euclidean space does not work for $n$-dimensional compact spacelike submanifolds of Lorentz-Minkowski ... More
Observational consequences of an interacting multiverseMay 28 2017The observability of the multiverse is at the very root of its physical significance as a scientific proposal. In this conference we present, within the third quantization formalism, an interacting scheme between the wave functions of different universes ... More
Restoration of matter-antimatter symmetry in the multiverseJun 20 2017In the multiverse, the universes can be created in entangled pairs with spacetimes that are both expanding in terms of the time variables experienced by internal observers in their particle physics experiments. The time variables of the two universes ... More
The Triangular Theorem of the Primes: Binary Quadratic Forms and Primitive Pythagorean TriplesFeb 21 2011Feb 22 2011This article reports the occurrence of binary quadratic forms in primitive Pythagorean triangles and their geometric interpretation. In addition to the well-known fact that the hypotenuse, z, of a right triangle, with sides of integral (relatively prime) ... More
Riemannian Geometry and the Fundamental Theorem of AlgebraJun 05 2011If a (non-constant) polynomial has no zero, then a certain Riemannian metric is constructed on the two dimensional sphere. Several geometric arguments are then shown to contradict this fact.
Embeddings for anisotropic Besov spacesSep 28 2006We prove embedding theorems for fully anisotropic Besov spaces. More concrete, inequalities between modulus of continuity in different metrics and of Sobolev type are obtained. Our goal is to get sharp estimates for some anisotropic cases previously unconsidered. ... More
Quantum cosmology of a conformal multiverseJun 19 2017In this paper it is studied the cosmology of a homogeneous and isotropic spacetime endorsed with a conformally coupled massless scalar field. We find six different solutions of the Friedmann equation that represent six different types of universes, all ... More
Subelliptic boundary value problems and The $G$-Fredholm PropertySep 08 2009Let $G$ be a unimodular Lie group, $X$ a compact manifold with boundary, and $M$ be the total space of a principal bundle $G\to M\to X$ so that $M$ is also a complex manifold satisfying a local subelliptic estimate. In this work, we show that if $G$ acts ... More
A transversal Fredholm property for the $\bar\partial$-Neumann problem on $G$-bundlesDec 21 2009Let $M$ be a strongly pseudoconvex complex $G$-manifold with compact quotient $M/G$. We provide a simple condition on forms $\alpha$ sufficient for the regular solvability of the equation $\square u=\alpha$ and other problems related to the $\bar\partial$-Neumann ... More
Visible and near-infrared observations of asteroid 2012 DA14 during its closest approach of February 15, 2013Mar 03 2013Jun 24 2013Near-Earth asteroid 2012 DA14 made its closest approach on February 15, 2013, when it passed at a distance of 27,700 km from the Earth's surface. It was the first time an asteroid of moderate size was predicted to approach that close to the Earth, becoming ... More
Discovery of Two Supernovae in the Nuclear Regions of the Luminous Infrared Galaxy IC 883Dec 04 2011We report the discovery of two consecutive supernovae (SNe), 2010cu and 2011hi, located at 0.37" (180 pc) and 0.79" (380 pc) projected distance respectively from the centre of the K-band nucleus of the luminous infrared galaxy IC 883. The SNe were discovered ... More
Discovery of a very highly extinguished supernova in a luminous infrared galaxyOct 16 2008Nov 17 2008We report the discovery of a confirmed supernova (SN) and a supernova-candidate in near-infrared images from the ALTAIR/NIRI adaptive optics system on the Gemini-North Telescope and NICMOS on the Hubble Space Telescope. The Gemini images were obtained ... More
The nature of supernovae 2010O and 2010P in Arp 299 - I. Near-infrared and optical evolutionNov 25 2013Apr 30 2014We present near-infrared and optical photometry, plus optical spectroscopy of two stripped-envelope supernovae (SNe) 2010O and 2010P that exploded in two different components of an interacting luminous infrared galaxy Arp 299 within only a few days of ... More
Serendipitous discovery of the long-sought AGN in Arp 299-AAug 26 2010Context: The dusty nuclear regions of luminous infra-red galaxies (LIRGs) are heated by either an intense burst of massive star formation, an active galactic nucleus (AGN), or a combination of both. Disentangling the contribution of each of those putative ... More
Ensemble Decision Systems for General Video Game PlayingMay 26 2019Ensemble Decision Systems offer a unique form of decision making that allows a collection of algorithms to reason together about a problem. Each individual algorithm has its own inherent strengths and weaknesses, and often it is difficult to overcome ... More
SDP Duals without Duality Gaps for a Class of Convex Minimax ProgramsJul 19 2013In this paper we introduce a new dual program, which is representable as a semi-definite linear programming problem, for a primal convex minimax programming model problem and show that there is no duality gap between the primal and the dual whenever the ... More
Ermakov approach for the one-dimensional Helmholtz HamiltonianJul 22 1997Jun 26 1999For the one-dimensional Helmholtz equation we write the corresponding time-dependent Helmholtz Hamiltonian in order to study it as an Ermakov problem and derive geometrical angles and phases in this context
Fermion confinement induced by geometryFeb 25 2011We consider a five-dimensional model in which fermions are confined in a hypersurface due to an interaction with a purely geometric field. Inspired by the Rubakov-Shaposhnikov field-theoretical model, in which massless fermions can be localized in a domain ... More
Adroitness: An Android-based Middleware for Fast Development of High-performance AppsJun 05 2019As smartphones become increasingly more powerful, a new generation of highly interactive user-centric mobile apps emerge to make user's life simpler and more productive. Mobile phones applications have to sustain limited resource availability on mobile ... More
Learning Human Optical FlowJun 14 2018Jul 22 2018The optical flow of humans is well known to be useful for the analysis of human action. Given this, we devise an optical flow algorithm specifically for human motion and show that it is superior to generic flow methods. Designing a method by hand is impractical, ... More
On human motion prediction using recurrent neural networksMay 06 2017Human motion modelling is a classical problem at the intersection of graphics and computer vision, with applications spanning human-computer interaction, motion synthesis, and motion prediction for virtual and augmented reality. Following the success ... More
Family of solutions for axisymmetric electrovacuum Einstein-Maxwell field equationsAug 09 2001We present a family of solutions for the axisymmetric Plebanski-Demianski metric and other corresponding reduced metrics. We also present the black hole characteristics using a new set of parameters for Kerr-Newman metric.
A symplectic approach to gravitational instabilityNov 24 1995We present a global approach of non-dissipative physics. Based on symplectic mechanics this technique allows us to obtain the solution of a very large class of problems in terms of a Taylor expand. We apply this method to the problem of gravitational ... More
Big-Bang Nucleosynthesis as a Probe of the Geometry of SuperspaceDec 28 1994Dec 29 1994We study the effect from a general ultralocal supermetric on primordial nucleosynthesis for Friedmann-Robertson-Walker Cosmology. The parameter $\lambda$ of the supermetric changes the effective number of degrees of freedom, $g_*$, which modifies the ... More
Quadrature rules for $L^1$-weighted norms of orthogonal polynomialsJul 09 2014In this paper we obtain $L^1$-weighted norms of classical orthogonal polynomials (Hermite, Laguerre and Jacobi polynomials) in terms of the zeros of these orthogonal polynomials; these expressions are usually known as quadrature rules. In particular these ... More
Sums of powers of Catalan triangle numbersFeb 13 2016In this paper we consider combinatorial numbers $C_{m, k}$ for $m\ge 1$ and $k\ge 0$ which unifies the entries of the Catalan triangles $ B_{n, k}$ and $ A_{n, k}$ for appropriate values of parameters $m$ and $k$, i.e., $B_{n, k}=C_{2n,n-k}$ and $A_{n, ... More
Magnetic Collapse of a Neutron Gas: No Magnetar FormationNov 30 2000A degenerate neutron gas in equilibrium with a background of electrons and protons in a magnetic field exerts its pressure anisotropically, having a smaller value perpendicular than along the magnetic field. For critical fields the magnetic pressure may ... More
Magnetic collapse of a neutron gas: Can magnetars indeed be formedMar 10 2003Mar 13 2003A relativistic degenerate neutron gas in equilibrium with a background of electrons and protons in a magnetic field exerts its pressure anisotropically, having a smaller value perpendicular than along the magnetic field. For critical fields the magnetic ... More
Regularity of the Hardy-Littlewood maximal operator on block decreasing functionsJul 01 2009We study the Hardy-Littlewood maximal operator defined via an unconditional norm, acting on block decreasing functions. We show that the uncentered maximal operator maps block decreasing functions of special bounded variation to functions with integrable ... More
Blind component separation for polarized observations of the CMBMar 02 2006Jan 09 2007We present in this paper the PolEMICA (Polarized Expectation-Maximization Independent Component Analysis) algorithm which is an extension to polarization of the SMICA (Spectral Matching Independent Component Analysis) temperature multi-detectors multi-components ... More
Unveiling the dominant gas heating mechanism in local LIRGs and ULIRGsDec 17 2008We show preliminary results from a sample of Luminous and Ultra-Luminous Infrared Galaxies (LIRGs and ULIRGs, respectively) in the local universe, obtained from observations using the Very Large Array (VLA), the Multi-Element Radio Link Interferometer ... More
Halo based reconstruction of the cosmic mass density fieldJul 06 2011We present the implementation of a halo based method for the reconstruction of the cosmic mass density field. The method employs the mass density distribution of dark matter haloes and its environments computed from cosmological N-body simulations and ... More
Rings, spirals and manifoldsDec 15 2008Feb 06 2009Two-armed, grand design spirals and inner and outer rings in barred galaxies can be due to orbits guided by the manifolds emanating from the vicinity of the L1 and L2 Lagrangian points, located at the ends of the bar. We first summarise the necessary ... More
Effect of the Introduction of Impurities on the Stability Properties of Multibreathers at Low CouplingJul 06 2004sing a theorem dubbed the {\em Multibreather Stabiliy Theorem} [Physica D 180 (2003) 235-255] we have obtained the stability properties of multibreathers in systems of coupled oscillators with on-site potentials, with an inhomogeneity. Analytical results ... More
The Chandra Multi-Wavelength Project: Optical Spectroscopy and the Broadband Spectral Energy Distributions of X-ray Selected AGNApr 23 2012Jun 20 2013From optical spectroscopy of X-ray sources observed as part of ChaMP, we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow up using the FLWO, SAAO, WIYN, CTIO, KPNO, Magellan, MMT and Gemini ... More
On the Probability of the Existence of Fixed-Size Components in Random Geometric GraphsJun 02 2008Jul 23 2008In this work we give precise asymptotic expressions on the probability of the existence of fixed-size components at the threshold of connectivity for random geometric graphs.
NanoSQUIDs: Basics & recent advancesSep 20 2016Superconducting Quantum Interference Devices (SQUIDs) are one of the most popular devices in superconducting electronics. They combine the Josephson effect with the quantization of magnetic flux in superconductors. This gives rise to one of the most beautiful ... More
The beta function of N=1 SYM in Differential RenormalizationFeb 13 2002Feb 27 2002Using differential renormalization, we calculate the complete two-point function of the background gauge superfield in pure N=1 Supersymmetric Yang-Mills theory to two loops. Ultraviolet and (off-shell) infrared divergences are renormalized in position ... More
Sharp threshold for hamiltonicity of random geometric graphsJul 07 2006We show for an arbitrary $\ell_p$ norm that the property that a random geometric graph $\mathcal G(n,r)$ contains a Hamiltonian cycle exhibits a sharp threshold at $r=r(n)=\sqrt{\frac{\log n}{\alpha_p n}}$, where $\alpha_p$ is the area of the unit disk ... More
Preparation to the CMB Planck analysis : contamination due to the polarized galactic emissionJul 19 2010The Planck satellite experiment, which was launched the 14th of may 2009, will give an accurate measurement of the anisotropies of the Cosmic Microwave Background (CMB) in temperature and polarization. This measurement is polluted by the presence of diffuse ... More
Neutrino Masses and GUT BaryogenesisApr 15 2004We reconsider the GUT-baryogenesis mechanism for generating the baryon asymmetry of the Universe. The baryon asymmetry is produced by the out of equilibrium decay of coloured Higgs bosons at the GUT scale, conserving B-L. If neutrinos are Majorana particles, ... More
Fractal dimension of interstellar clouds: opacity and noise effectsOct 20 2006There exists observational evidence that the interstellar medium has a fractal structure in a wide range of spatial scales. The measurement of the fractal dimension (Df) of interstellar clouds is a simple way to characterize this fractal structure, but ... More
Electronic structure of CdTe nanocrystals: A tight-binding studyFeb 09 1999We present a symmetry-based calculation of the electronic structure of a compound semiconductor quantum dot (QD) in the sp^3s* tight-binding model including the spin-orbit interaction. The Hamiltonian matrix is diagonalized exactly for CdTe QD sizes up ... More
Electroweak Baryogenesis from Late Neutrino MassesApr 27 2005Sep 13 2005Electroweak Baryogenesis, given a first order phase transition, does not work in the standard model because the quark Yukawa matrices are too hierarchical. On the other hand, the neutrino mass matrix is apparently not hierarchical. In models with neutrino ... More
Friedel Oscillations in Relativistic Nuclear MatterJul 01 1994We calculate the low-momentum N-N effective potential obtained in the OBE approximation, inside a nuclear plasma at finite temperature, as described by the relativistic $ \sigma $-$ \omega $ model. We analyze the screening effects on the attractive part ... More
The Fractal Dimension of Projected CloudsJan 26 2005Feb 18 2005The interstellar medium seems to have an underlying fractal structure which can be characterized through its fractal dimension. However, interstellar clouds are observed as projected two-dimensional images, and the projection of a tri-dimensional fractal ... More
Exciton states and optical properties of CdSe nanocrystalsJun 06 2001The optical spectra of CdSe nanocrystals up to 55 A in diameter are analyzed in a wide range of energies from the fine structure of the low-energy excitations to the so-called high-energy transitions. We apply a symmetry-based method in two steps. First ... More
Path Integral Approach to Residual Gauge FixingSep 07 2004Oct 27 2004In this paper we study the question of residual gauge fixing in the path integral approach for a general class of axial-type gauges including the light-cone gauge. We show that the two cases -- axial-type gauges and the light-cone gauge -- lead to very ... More
Gauge-Invariant Operators for Singular Knots in Chern-Simons Gauge TheoryDec 15 1997We construct gauge invariant operators for singular knots in the context of Chern-Simons gauge theory. These new operators provide polynomial invariants and Vassiliev invariants for singular knots. As an application we present the form of the Kontsevich ... More
Fully-Balanced Heat InterferometerOct 26 2012Apr 04 2013A tunable and balanced heat interferometer is proposed and analyzed. The device consists of two superconductors linked together to form a double-loop interrupted by three Josephson junctions coupled in parallel. Both superconductors are held at different ... More
Phase-controlled superconducting heat-flux quantum modulatorMay 14 2012We theoretically put forward the concept of a phase-controlled superconducting heat-flux quantum modulator. Its operation relies on phase-dependent heat current predicted to occur in temperature-biased Josephson tunnel junctions. The device behavior is ... More
The Josephson heat interferometerMay 15 2012The Josephson effect represents perhaps the prototype of macroscopic phase coherence and is at the basis of the most widespread interferometer, i.e., the superconducting quantum interference device (SQUID). Yet, in analogy to electric interference, Maki ... More
Robust SOS-Convex Polynomial Programs: Exact SDP RelaxationsJul 20 2013Oct 07 2013This paper studies robust solutions and semidefinite linear programming (SDP) relaxations of a class of convex polynomial programs in the face of data uncertainty. The class of convex programs, called robust SOS-convex programs, includes robust quadratically ... More
Majorana neutrino oscillations in vacuumMar 14 2011Jun 14 2012In the context of a type I seesaw scenario which leads to get light left-handed and heavy right-handed Majorana neutrinos, we obtain expressions for the transition probability densities between two flavor neutrinos in the cases of left-handed and right-handed ... More
Electronic structure and optical properties of ZnS/CdS nanoheterostructuresJun 16 2003The electronic and optical properties of spherical nanoheterostructures are studied within the semi-empirical $sp^{3}s^{*}$ tight-binding model including the spin-orbit interaction. We use a symmetry-based approach previously applied to CdSe and CdTe ... More
Pattern formation in parametric sound generationMay 06 2005Pattern formation of sound is predicted in a driven resonator where subharmonic generation takes place. A model allowing for diffraction of the fields (large-aspect ratio limit) is derived by means of the multiple scale expansions technique. An analysis ... More
Vassiliev Invariants in the Context of Chern-Simons Gauge TheoryDec 13 1998Dec 20 1998We summarize the progress made during the last few years on the study of Vassiliev invariants from the point of view of perturbative Chern-Simons gauge theory. We argue that this approach is the most promising one to obtain a combinatorial universal formula ... More
Kontsevich Integral for Vassiliev Invariants from Chern-Simons Perturbation Theory in the Light-Cone GaugeOct 23 1997We analyse the structure of the perturbative series expansion of Chern-Simons gauge theory in the light-cone gauge. After introducing a regularization prescription that entails the consideration of framed knots, we present the general form of the vacuum ... More
Möbius solutions of the curved $n$--body problem for positive curvatureJul 03 2012Aug 22 2012We denote by $\mathbb{M}^2_R$ a two dimensional space of constant positive Gaussian curvature. With methods of M\"obius geometry and using the classification of the M\"obius group of automorphisms ${\rm \bf Mob}_2 \, (\hat{\mathbb{C}})$ of the Riemman ... More
Constraining decaying dark matter with neutron starsMar 24 2014Apr 07 2015The amount of decaying dark matter, accumulated in the central regions in neutron stars together with the energy deposition rate from decays, may set a limit on the neutron star survival rate against transitions to more compact objects provided nuclear ... More
Chiral current generation in QED by longitudinal photonsFeb 03 2016We report the generation of a pseudovector electric current having imbalanced chirality in an electron-positron strongly magnetized gas in QED. It propagates along the external applied magnetic field B as a chiral magnetic effect in QED. It is triggered ... More
Forest structure in epigenetic landscapesMar 22 2019Morphogenesis is the biological process that causes the emergence and changes of patterns (tissues and organs) in living organisms. It is a robust, self-organising mechanism, governed by Genetic Regulatory Networks (GRN), that hasn't been thoroughly understood. ... More
Realistic Neutrino Opacities for Supernova Simulations With Correlations and Weak MagnetismMay 08 2003May 09 2003Advances in neutrino transport allow realistic neutrino interactions to be incorporated into supernova simulations. We add tensor couplings to relativistic RPA calculations of neutrino opacities. Our results reproduce free-space neutrino-nucleon cross ... More
Determining the Fractal Dimension of the Interstellar MediumMar 10 2008The Interstellar Medium seems to have an underlying fractal structure, which can be characterized through its fractal dimension (Df). However, several factors may affect the determination of Df, such as distortions due to projection, low image resolution, ... More
On the properties of fractal cloud complexesDec 09 2005We study the physical properties derived from interstellar cloud complexes having a fractal structure. We first generate fractal clouds with a given fractal dimension and associate each clump with a maximum in the resulting density field. Then, we discuss ... More
CdS/HgS/CdS Quantum Dot Quantum Wells: A Tight-binding StudyFeb 25 2002We study the electronic properties of spherical quantum dot quantum well nanocrystals within a symmetry-based tight-binding model. In particular, the influence of a concentric monolayer of HgS embedded in a spherical CdS nanocrystal of diameter 52.7 A ... More
Combinatorial Formulae for Vassiliev Invariants from Chern-Simons Gauge TheoryJul 20 1998Jul 21 1998We analyse the perturbative series expansion of the vacuum expectation value of a Wilson loop in Chern-Simons gauge theory in the temporal gauge. From the analysis emerges the notion of the kernel of a Vassiliev invariant. The kernel of a Vassiliev invariant ... More
Unruh Effect in the General Light-Front FrameFeb 28 2005Jun 13 2005We study the phenomenon of Unruh effect in a massless scalar field theory quantized on the light-front in the general light-front frame. We determine the uniformly accelerating coordinates in such a frame and through a direct transformation show that ... More
G337.2+0.1: a new X-ray supernova remnant?Jan 04 2005We present evidence supporting a SNR origin for the radio source G337.2+0.1, which was discovered along the line of sight to the Norma spiral arm in the MOST 843-MHz radio survey. The radio source is spatially superposed to the unidentified ASCA source ... More
Spectral and variability properties of LS 5039 from radio to very high-energy gamma-raysMay 19 2006Microquasars are X-ray binaries with relativistic jets. The microquasar LS 5039 turned out to be the first high-energy gamma-ray microquasar candidate due to its likely association with the EGRET source 3EG J1824-1514. Further theoretical studies supported ... More
Dark matter and dark energy accretion onto intermediate-mass black holesNov 23 2011Mar 08 2012In this work we investigate the accretion of cosmological fluids onto an intermediate-mass black hole at the centre of a globular cluster, focusing on the influence of the parent stellar system on the accretion flow. We show that the accretion of cosmic ... More
Circumventing Magnetic Reciprocity: a Magnetic DiodeJan 30 2018Lorentz reciprocity establishes a stringent relation between electromagnetic fields and their sources. For static magnetic fields a relation between magnetic sources and fields can be drawn in analogy to the Green's reciprocity principle for electrostatics. ... More
Simple quantum model for light depolarizationJun 10 2004Oct 24 2005Depolarization of quantum fields is handled through a master equation of the Lindblad type. The specific feature of the proposed model is that it couples dispersively the field modes to a randomly distributed atomic reservoir, much in the classical spirit ... More
General Relativity and Weyl FramesJun 28 2011We present the general theory of relativity in the language of a non-Riemannian geometry, namely, Weyl geometry. We show that the new mathematical formalism may lead to different pictures of the same gravitational phenomena, by making use of the concept ... More
Embedding Gödel's universe in five dimensionsMar 30 2005Oct 19 2005According to the Campbell-Magaard theorem, any analytical spacetime can be locally and analytically embedded into a five-dimensional pseudo-Riemannian Ricci-flat manifold. We find explicitly this embedding for Godel's universe. The embedding space is ... More
Nonclassical Kinetics in Constrained Geometries: Initial Distribution EffectsJun 09 1998We present a detailed study of the effects of the initial distribution on the kinetic evolution of the irreversible reaction A+B -> 0 in one dimension. Our analytic as well as numerical work is based on a reaction-diffusion model of this reaction. We ... More
Warp evidences in precessing galactic bar modelsJan 19 2016Most galaxies have a warped shape when they are seen from an edge-on point of view. The reason for this curious form is not completely known so far and in this work we apply dynamical system tools to contribute to its explanation. Starting from a simple, ... More
$zT$-factor enhancement in SnSe: predictions from first principles calculationsDec 18 2016The electronic structure and thermoelectric properties of SnSe are studied by first-principles methods. The inclusion of van der Waals dispersive corrections improves the agreement of structural parameters with experiments. The bands structure and projected ... More
Higgs inflation in complex geometrical scalar-tensor theory of gravityAug 17 2019We derive a Higgs inflationary model in the context of a complex geometrical scalar-tensor theory of gravity. In this model the Higgs inflaton scalar field has geometrical origin playing the role of the Weyl scalar field in the original non-riemannian ... More
High-mass microquasars and low-latitude gamma-ray sourcesMay 03 2004Sep 09 2004Population studies of unidentified EGRET sources suggest that there exist at least three different populations of galactic gamma-ray sources. One of these populations is formed by young objects distributed along the galactic plane with a strong concentration ... More
INFaaS: Managed & Model-less Inference ServingMay 30 2019The number of applications relying on inference from machine learning models is already large and expected to keep growing. For instance, Facebook applications issue tens-of-trillions of inference queries per day with varying performance, accuracy, and ... More
Optomechanics assisted with a qubit: From dissipative state preparation to many-body physicsMay 29 2013We propose and analyze nonlinear optomechanical protocols that can be implemented by adding a single atom to an optomechanical cavity. In particular, we show how to engineer the environment in order to dissipatively prepare the mechanical oscillator in ... More