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Depth with respect to a family of convex setsDec 11 2016We propose a notion of depth with respect to a finite family $\mathcal{F}$ of convex sets in $\mathbb{R}^d$ which we call $\text{dep}_\mathcal{F}$. We begin showing that $\text{dep}_\mathcal{F}$ satisfies some expected properties for a measure of depth ... More

Bounding a global red-blue proportion using local conditionsJan 09 2017Apr 20 2017We study the following local-to-global phenomenon: Let $B$ and $R$ be two finite sets of (blue and red) points in the Euclidean plane $\mathbb{R}^2$. Suppose that in each "neighborhood" of a red point, the number of blue points is at least as large as ... More

Further Consequences of the Colorful Helly HypothesisMar 16 2018Let $\mathcal{F}$ be a family of convex sets in ${\mathbb R}^d$, which are colored with $d+1$ colors. We say that $\mathcal{F}$ satisfies the Colorful Helly Property if every rainbow selection of $d+1$ sets, one set from each color class, has a non-empty ... More

Complete Kneser TransversalsNov 04 2015Aug 12 2016Let $k,d,\lambda\geqslant1$ be integers with $d\geqslant\lambda $. Let $m(k,d,\lambda)$ be the maximum positive integer $n$ such that every set of $n$ points (not necessarily in general position) in $\mathbb{R}^{d}$ has the property that the convex hulls ... More

Singularities and internal rotational dynamics of electron beamsAug 02 2016We study the internal rotational dynamics of electronic beams in relation to the phase singularities of their wave functions. Given their complex singularity structure, Hermite-Gaussian beams and other superpositions of Laguerre-Gaussian modes are studied ... More

On lattice path matroid polytopes: integer points and Ehrhart polynomialJan 19 2017Oct 25 2017In this paper we investigate the number of integer points lying in dilations of lattice path matroid polytopes. We give a characterization of such points as polygonal paths in the diagram of the lattice path matroid. Furthermore, we prove that lattice ... More

A sunflower anti-Ramsey theorem and its applicationsMay 19 2015A $h$-sunflower in a hypergraph is a family of edges with $h$ vertices in common. We show that if we colour the edges of a complete hypergraph in such a way that any monochromatic $h$-sunflower has at most $\lambda$ petals, then it contains a large rainbow ... More

A Tutte polynomial inequality for lattice path matroidsOct 02 2015Oct 27 2016Let $M$ be a matroid without loops or coloops and let $T(M;x,y)$ be its Tutte polynomial. In 1999 Merino and Welsh conjectured that $$\max(T(M;2,0), T(M;0,2))\geq T(M;1,1)$$ holds for graphic matroids. Ten years later, Conde and Merino proposed a multiplicative ... More

A Tutte polynomial inequality for lattice path matroidsOct 02 2015Jun 20 2016Let $M$ be a matroid without loops or coloops and let $T(M;x,y)$ be its Tutte polynomial. In 1999 Merino and Welsh conjectured that $$\max(T(M;2,0), T(M;0,2))\geq T(M;1,1)$$ holds for graphic matroids. Ten years later, Conde and Merino proposed a multiplicative ... More

Geometric Hamilton-Jacobi theory for higher-order autonomous systemsSep 09 2013May 19 2014The geometric framework for the Hamilton-Jacobi theory is used to study this theory in the ambient of higher-order mechanical systems, both in the Lagrangian and Hamiltonian formalisms. Thus, we state the corresponding Hamilton-Jacobi equations in these ... More

Detection of vertical muons with the HAWC water Cherenkov detectors and its application to gamma/hadron discriminationAug 30 2017The HAWC observatory reconstructs atmospheric showers induced by very high-energy primary cosmic- or gamma-rays. Cosmic-rays with hadronic nature are several orders of magnitude more frequent than primary gammas and therefore it is necessary to perform ... More

ASB1 differential methylation in ischaemic cardiomyopathy. Relationship with left ventricular performance in end stage heart failure patientsApr 04 2017Aims: Ischaemic cardiomyopathy (ICM) leads to impaired contraction and ventricular dysfunction causing high rates of morbidity and mortality. Epigenomics allows the identification of epigenetic signatures in human diseases. We analyse the differential ... More

IDTxl: The Information Dynamics Toolkit xl: a Python package for the efficient analysis of multivariate information dynamics in networksJul 27 2018Feb 19 2019The Information Dynamics Toolkit xl (IDTxl) is a comprehensive software package for efficient inference of networks and their node dynamics from multivariate time series data using information theory. IDTxl provides functionality to estimate the following ... More

Triangle areas determined by arrangements of planar linesFeb 08 2019A widely investigated subject in combinatorial geometry, originated from Erd\H{o}s, is the following. Given a point set $P$ of cardinality $n$ in the plane, how can we describe the distribution of the determined distances? This has been generalized in ... More

Codimension two and three Kneser TransversalsJan 04 2016Sep 27 2016Let $k,d,\lambda \geqslant 1$ be integers with $d\geqslant \lambda $ and let $X\subset\mathbb{R}^{d}$ be a finite set. A $(d-\lambda)$-plane $L$ transversal to the convex hull of all $k$-sets of $X$ is called Kneser transversal. If in addition $L$ contains ... More

Codimension two and three Kneser TransversalsJan 04 2016Nov 15 2017Let $k,d,\lambda \geqslant 1$ be integers with $d\geqslant \lambda $ and let $X$ be a finite set of points in $\mathbb{R}^{d}$. A $(d-\lambda)$-plane $L$ transversal to the convex hulls of all $k$-sets of $X$ is called Kneser transversal. If in addition ... More

Pruning a Minimum Spanning TreeSep 03 2011This work employs some techniques in order to filter random noise from the information provided by minimum spanning trees obtained from the correlation matrices of international stock market indices prior to and during times of crisis. The first technique ... More

The Singularities of the Wave Trace of the Basic Laplacian of a Riemannian FoliationAug 14 2006We apply techniques of microlocal analysis to the study of the transverse geometry of Riemannian foliations in order to analyze spectral invariants of the basic Laplacian acting on functions on a Riemannian foliation with a bundle-like metric. In particular, ... More

The Wave Trace Invariants of the Spectrum of the $G$-Invariant LaplacianNov 07 2013Given a compact boundaryless Riemannian manifold $Y$ on which a compact Lie group $G$ acts, there is always a metric on $Y$ such that the action is by isometries. Assuming $Y$ is equipped with such a metric, recall that the $G$-invariant Laplacian is ... More

A 1D kinetic model for CMB ComptonizationJul 17 2019This work presents a novel derivation of the expressions that describe the distortions of the CMB curve due to the interactions between photons and the electrons present in dilute ionized systems. In this approach, a simplified a one-dimensional evolution ... More

Differential Calculus on Iso_q (N), Quantum Poincare' Algebra and q - GravityDec 22 1993Jan 06 1994We present a general method to deform the inhomogeneous algebras of the $B_n,C_n,D_n$ type, and find the corresponding bicovariant differential calculus. The method is based on a projection from $B_{n+1}, C_{n+1}, D_{n+1}$. For example we obtain the (bicovariant) ... More

Super-renormalizable Higher-Derivative Quantum GravityJan 31 2012In this paper we study perturbatively an extension of the Stelle higher derivative gravity involving an infinite number of derivative terms. We know that the usual quadratic action is renormalizable but is not unitary because of the presence of a ghost ... More

Análise Assintótica de Soluções de Equações Difusivas Não-Lineares via Métodos de Escalas MúltiplasMay 11 2006Mar 14 2011In the present work we shall describe and apply the techniques of the Renormalization Group - based in data rescaling and operator renormalizing - and of Homogenization - that substitutes, in a certain limit, a periodically inhomogeneous medium by a homogeneous ... More

Ballistic quantum state transfer in spin chains: general theory for quasi-free models and arbitrary initial statesAug 31 2013Oct 15 2013Ballistic quantum-information transfer through spin chains is based on the idea of making the spin dynamics ruled by collective excitations with linear dispersion relation. Unlike perfect state transfer schemes, a ballistic transmission requires only ... More

Some arithmetic proerties of Lame operators with dihedral monodromyMar 17 2004In this paper, we describe some arithmetic properties of Lame operators with finite dihedral projective monodromy. We take advantage of the deep link with Grothendieck's theory of dessins d'enfants. We focus more particularly on the case of projective ... More

Asymptotically hyperbolic manifolds with polyhomogeneous metricNov 27 2008Sep 08 2009We analyze the resolvent and define the scattering matrix for asymptotically hyperbolic manifolds with metrics which have a polyhomogeneous expansion near the boundary, and also prove that there is always an essential singularity of the resolvent in this ... More

Absence of Resonances near Critical Line for CC ManifoldsJul 01 2011Oct 09 2013We find a resonance free region polynomially close to the critical line on Conformally compact manifolds with polyhomogeneous metric.

Super Star Clusters in the Blue Dwarf Galaxy UM 462Jul 03 2003I present optical observations of the Blue Compact Dwarf Galaxy UM 462. The images of this galaxy show several bright compact sources. A careful study of these sources has revealed their nature of young Super Star Clusters. The ages determined from the ... More

Noncommutative geometry and physics: a review of selected recent resultsMay 23 2000Aug 02 2000This review is based on two lectures given at the 2000 TMR school in Torino. We discuss two main themes: i) Moyal-type deformations of gauge theories, as emerging from M-theory and open string theories, and ii) the noncommutative geometry of finite groups, ... More

On G/H geometry and its use in M-theory compactificationsDec 30 1999The Riemannian geometry of coset spaces is reviewed, with emphasis on its applications to supergravity and M-theory compactifications. Formulae for the connection and curvature of rescaled coset manifolds are generalized to the case of nondiagonal Killing ... More

The Lagrangian of q-Poincare' GravityFeb 07 1994Feb 17 1994The gauging of the q-Poincar\'e algebra of ref. hep-th 9312179 yields a non-commutative generalization of the Einstein-Cartan lagrangian. We prove its invariance under local q-Lorentz rotations and, up to a total derivative, under q-diffeomorphisms. The ... More

On the quantum Poincare' groupDec 02 1992The inhomogeneous quantum groups $IGL_q(n)$ are obtained by means of a particular projection of $GL_q(n+1)$. The bicovariant differential calculus on $GL_q(n)$ is likewise projected into a consistent bicovariant calculus on $IGL_q(n)$. Applying the same ... More

Gauge theories of quantum groupsMay 28 1992We find two different q-generalizations of Yang-Mills theories. The corresponding lagrangians are invariant under the q-analogue of infinitesimal gauge transformations. We explicitly give the lagrangian and the transformation rules for the bicovariant ... More

Non orientable three-submanifolds of $\mathrm{G}_2-$manifoldsSep 06 2016By analogy with associative and co-associative cases we introduce a class of three and four-dimensional submanifolds of almost $\mathrm{G}_2-$manifolds (possibly with torsion) modelled on planes lying in a special $\mathrm{G}_2-$orbit. Since $\mathrm{G}_2$ ... More

Notes on quantum fields on two dimensional spacetimesNov 23 2014We point out how to construct the Hartle-Hawking-Israel state for the minimaly coupled massless quantum real scalar field in the two dimensional BTZ black hole. We also calculate the renormalized energy-momentum tensor for the same field in the eternal ... More

Electromagnetism with dimension-five operatorsSep 24 2014Nov 13 2014We derive, in curved spacetime, the most general Lorentz-violating electromagnetic Lagrangian containing dimension-five operators with one more derivative than the Maxwell term in the hypothesis that Lorentz symmetry is broken by a background four-vector ... More

Relating spontaneous and explicit symmetry breaking in the presence of the Higgs mechanismMay 05 2016Nov 28 2016One common way to define spontaneous symmetry breaking involves necessarily explicit symmetry breaking. We study Quantum Field Theories extending the Standard Model, without anomalies. We add explicit symmetry breaking terms to the Higgs potential, so ... More

Rational Krylov and ADI iteration for infinite size quasi-Toeplitz matrix equationsJul 05 2019Aug 09 2019We consider a class of linear matrix equations involving semi-infinite matrices which have a quasi-Toeplitz structure. These equations arise in different settings, mostly connected with PDEs or the study of Markov chains such as random walks on bidimensional ... More

To Split or Not to Split, That Is the Question in Some Shallow Water EquationsNov 28 2012In this paper we analyze the use of time splitting techniques for solving shallow water equation. We discuss some properties that these schemes should satisfy so that interactions between the source term and the shock waves are controlled. This paper ... More

Tilted Ghost InflationJun 07 2004May 22 2005In a ghost inflationary scenario, we study the observational consequences of a tilt in the potential of the ghost condensate. We show how the presence of a tilt tends to make contact between the natural predictions of ghost inflation and the ones of slow ... More

Antiferromagnetic effects in Chaotic Map lattices with a conservation lawJul 04 2002Some results about phase separation in coupled map lattices satisfying a conservation law are presented. It is shown that this constraint is the origin of interesting antiferromagnetic effective couplings and allows transitions to antiferromagnetic and ... More

Chern-Simons supergravities, with a twistMay 07 2013Jul 24 2013We discuss noncommutative extensions of Chern-Simons (CS) supergravities in odd dimensions. The example of D=5 CS supergravity, invariant under the gauge supergroup SU(2,2|N), is worked out in detail. Its noncommutative version is found to exist only ... More

De Sitter Relativity and Cosmological PrincipleJun 24 2010Jan 31 2011The formalism of Fantappie-Arcidiacono Projective General Relativity - also known as De Sitter Relativity - has recently been revised in order to make possible cosmological models with expansion, similarly to ordinary Fridman cosmology formulated within ... More

Origin of Cosmic Magnetic FieldsApr 24 2013Aug 26 2013We calculate, in the free Maxwell theory, the renormalized quantum vacuum expectation value of the two-point magnetic correlation function in de Sitter inflation. We find that quantum magnetic fluctuations remain constant during inflation instead of being ... More

The Rise of Solitons in Sine-Gordon Field Theory: From Jacobi Amplitude to Gudermannian FunctionNov 20 2014We show how the famous soliton solution of the classical sine-Gordon field theory in $(1+1)$-dimensions may be obtained as a particular case of a solution expressed in terms of the Jacobi amplitude, which is the inverse function of the incomplete elliptic ... More

Local models and hidden nonlocality in Quantum TheoryJul 22 2014This Master's thesis has two central subjects: the simulation of correlations generated by local measurements on entangled quantum states by local hidden-variables models and the revelation of hidden nonlocality. We present and detail the Werner's local ... More

(3+1)-dimensional framework for leading-order non conformal anisotropic hydrodynamicsNov 26 2014May 24 2015In this work I develop a new framework for anisotropic hydrodynamics that generalizes the leading order of the hydrodynamic expansion to the full (3+1)-dimensional anisotropic massive case. Following previous works, my considerations are based on the ... More

Finitary Process Evolution I: Information Geometry of Configuration Space and the Process-Replicator DynamicsJul 12 2018Jul 25 2018This report presents some fundamental mathematical results towards elucidating the information-geometric underpinnings of evolutionary modelling schemes for (quasi-)stationary discrete stochastic processes. The model class under consideration is that ... More

A Pragmatic Smoothing Method for Improving the Quality of the Results in Atomic SpectroscopyMar 07 2016A new smoothing method for the improvement on the identification and quantification of spectral functions based on the previous knowledge of the signals that are expected to be quantified, is presented. These signals are used as weighted coefficients ... More

Hierarchy from BaryogenesisJul 21 2005Feb 19 2006We study a recently proposed mechanism to solve the hierarchy problem in the context of the landscape, where the solution of the hierarchy problem is connected to the requirement of having baryons in our universe via Electroweak Baryogenesis. The phase ... More

Archetypes, Causal Description and Creativity in Natural WorldJul 10 2006The idea, formulated for the first time by Pauli, of a "creativity" of natural processes on a quantum scale is briefly investigated, with particular reference to the phenomena, common throughout the biological world, involved in the amplification of microscopic ... More

The transaction as a quantum conceptApr 24 2012This essay intends to present a novel approach to the concept of "transaction" in quantum physics. Breaking with Cramer's original theory, the transaction is not connected to the simultaneously retarded and advanced spacetime propagation of classical ... More

A geometric Hall-type theoremDec 20 2014Jan 14 2015We introduce a geometric generalization of Hall's marriage theorem. For any family $F = \{X_1, \dots, X_m\}$ of finite sets in $\mathbb{R}^d$, we give conditions under which it is possible to choose a point $x_i\in X_i$ for every $1\leq i \leq m$ in such ... More

The SU(2)-character varieties of torus knotsFeb 15 2012Feb 23 2012Let G be the fundamental group of the complement of the torus knot of type (m,n). We study the relationship between SU(2) and SL(2,C)-representations of this group, looking at their characters. Using the description of the SL(2,C)-character variety of ... More

Brillouin scattering and the CMBMay 18 2001Jan 13 2005Brillouin scattering of photons off the density fluctuations in a fluid is potentially important for cosmology. We derive the Brillouin spectral distortion of blackbody radiation, and discuss the possible implications for the cosmic microwave background. ... More

Thermal fluctuations propagation in the relativistic Euler regime: a causal appraisalMay 15 2009It is shown that thermal fluctuations present in a simple non-degenerate relativistic fluid satisfy a wave equation in the Euler regime. The characteristic propagation speeds are calculated and the classical expression for the speed of sound is recovered ... More

The Néron-Severi Lie Algebra of a Soergel ModuleJul 19 2016We introduce the N\'eron-Severi Lie algebra of a Soergel module and we determine it for a large class of Schubert varieties. This is achieved by investigating which Soergel modules admit a tensor decomposition. We also use the N\'eron-Severi Lie algebra ... More

How heavy can the Fermions in Split Susy be? A study on Gravitino and Extradimensional LSPDec 08 2004May 20 2005In recently introduced Split Susy theories, in which the scale of Susy breaking is very high, the requirement that the relic abundance of the Lightest SuperPartner (LSP) provides the Dark Matter of the Universe leads to the prediction of fermionic superpartners ... More

The Fundamental Equations of Point, Fluid and Wave Dynamics in the De Sitter-Fantappie-Arcidiacono Projective Relativity TheoryJan 23 2009A review is presented of the fundamental equations of point, perfect incompressible fluid and wave dynamics in the Fantappie-Arcidiacono theory of projective relativity, also known as De Sitter relativity. Compared to the original works, some deductions ... More

Fantappié-Arcidiacono theory of relativity versus recent cosmological evidences : a preliminary comparisonFeb 21 2007May 10 2007Notwithstanding the Fantappie-Arcidiacono theory of relativity was introduced more than half a century ago, its observational confirmations in cosmology (the only research field where its predictions differ from those of the Einsteinian relativity) are ... More

Relating spontaneous and explicit symmetry breaking in the presence of the Higgs mechanismMay 05 2016One common way to define spontaneous symmetry breaking involves necessarily explicit symmetry breaking. We add explicit symmetry breaking terms to the Higgs potential, so that the spontaneous breaking of a global symmetry in multi-Higgs-doublet models ... More

On the essential spectrum of the Laplacian and the drifted LaplacianFeb 07 2013Apr 26 2013This paper concerns the $L^2$ essential spectrum of the Laplacian $\Delta$ and the drift Laplacian $\Delta_f$ on complete Riemannian manifolds endowed with a weighted measure $e^{-f}d\;vol_g$. We prove that the essential spectrum of the drift Laplacian ... More

Super-renormalizable Quantum GravityJul 12 2011In this paper we study perturbatively an extension of the Stelle higher derivative gravity involving an infinite number of derivative terms. We know that the usual quadratic action is renormalizable but suffers of the unitarity problem because of the ... More

OSp(1|4) supergravity and its noncommutative extensionJan 08 2013Jul 24 2013We review the OSp(1|4)-invariant formulation of N=1, D=4 supergravity and present its noncommutative extension, based on a star-product originating from an abelian twist with deformation parameter \theta. After use of a geometric generalization of the ... More

Helium-4 Synthesis in an Anisotropic UniverseDec 09 2011Dec 30 2011We calculate the 4He abundance in a universe of Bianchi type I whose cosmic anisotropy is dynamically generated by a fluid with anisotropic equation of state. Requiring that the relative variation of mass fraction of 4He is less than 4% with respect to ... More

Specialization of polynomial covers of prime degreeOct 09 2002Let K be a complete field of unequal characteristics $(0,p)$. The aim of this paper is to describe the the semi-stable models for covers $\bold P^1_K@>>>\bold P^1_K$ of degree p, unramified outside $r\leq p$ points and totally ramified above one of them, ... More

Supergravity in the group-geometric framework: a primerFeb 09 2018Mar 05 2018We review the group-geometric approach to supergravity theories, in the perspective of recent developments and applications. Usual diffeomorphisms, gauge symmetries and supersymmetries are unified as superdiffeomorphisms in a supergroup manifold. Integration ... More

Towards a Field Theoretical Stochastic Model for Description of Tumour GrowthMay 08 2017We develop a field theory-inspired stochastic model for description of tumour growth based on an analogy with an SI epidemic model, where the susceptible individuals (S) would represent the healthy cells and the infected ones (I), the cancer cells. From ... More

An ad-hoc modified Likelihood Function Applied to Optimization of Data Analysis in Atomic SpectroscopyApr 11 2017In this paper we propose an ad-hoc construction of the Likelihood Function, in order to develop a data analysis procedure, to be applied in atomic and nuclear spectral analysis. The classical Likelihood Function was modified taking into account the underlying ... More

A Pragmatic Smoothing Method for Improving the Quality of the Results in Atomic SpectroscopyMar 07 2016Jan 30 2017A new smoothing method for the improvement on the identification and quantification of spectral functions based on the previous knowledge of the signals that are expected to be quantified, is presented. These signals are used as weighted coefficients ... More

Super-renormalizable or Finite Lee-Wick Quantum GravityFeb 07 2016We propose a class of multidimensional higher derivative theories of gravity without extra real degrees of freedom besides the graviton field. The propagator shows up the usual real graviton pole and extra complex conjugates poles that do not contribute ... More

Gauge Fixing and the Semiclassical Interpretation of Quantum CosmologyJan 21 2019Aug 10 2019We make a critical review of the semiclassical interpretation of quantum cosmology and emphasise that it is not necessary to consider that a concept of time emerges only when the gravitational field is (semi)classical. We show that the usual results of ... More

Relating the wave-function collapse with Euler's formulaNov 15 2017Sep 17 2018One attractive interpretation of quantum mechanics is the ensemble interpretation, where Quantum Mechanics merely describes a statistical ensemble of objects and not individual objects. But this interpretation does not address why the wave-function plays ... More

Unique ergodicity for stochastic hyperbolic equations with additive space-time white noiseNov 15 2018Jul 11 2019In this paper, we consider a certain class of second order nonlinear PDEs with damping and space-time white noise forcing, posed on the $d$-dimensional torus. This class includes the wave equation for $d=1$ and the beam equation for $d\le 3$. We show ... More

Hamiltonian actions and Lagrangian homogeneous submanifoldsMay 22 2006We consider a connected symplectic manifold $M$ acted on properly and in a Hamiltonian fashion by a connected Lie group $G$. Inspired to the recent paper \cite{gb2}, see also \cite{ch} and \cite{pacini}, we study Lagrangian orbits of Hamiltonian actions. ... More

Convexity properties of gradient maps associated to real reductive representationsMay 06 2019Let G be a connected real reductive Lie group acting linearly on a finite dimensional vector space V over R. This action admits a Kempf-Ness function and so we have an associated gradient map. If G is Abelian we explicitly compute the image of G orbits ... More

Superresolution method for data deconvolution by superposition of point sourcesMay 08 2018Dec 05 2018In this work we present a new algorithm for data deconvolution that allows the retrieval of the target function with super-resolution with a simple approach that after a precis e measurement of the instrument response function (IRF), the measured data ... More

Higher-order Variational Calculus on Lie algebroidsJan 26 2015The equations for the critical points of the action functional defined by a Lagrangian depending on higher-order derivatives of admissible curves on a Lie algebroid are found. The relation with Euler-Poincar\'e and Lagrange Poincar\'e type equations is ... More

Points defining triangles with distinct circumradiiFeb 25 2014Paul Erdos asked if, among sufficiently many points in general position, there are always $k$ points such that all the circles through $3$ of these $k$ points have different radii. He later proved that this is indeed the case. However, he overlooked a ... More

Cosmological bulk viscosity, the Burnett regime, and the BGK equationOct 25 2002Einstein's field equations in FRW space-times are coupled to the BGK equation in order to derive the stress energy tensor including dissipative effects up to second order in the thermodynamical forces. The space-time is assumed to be matter-dominated, ... More

The thermal and kinematic Sunyaev-Zel'dovich effects revisitedOct 16 2003This paper shows that a simple convolution integral expression based on the mean value of the isotropic frequency distribution corresponding to photon scattering off electrons leads to useful analytical expressions describing the thermal Sunyaev-Zel'dovich ... More

Note on the Sunyaev-Zel'dovich thermal effectMay 08 2003Jun 12 2003In a previous publication we have derived an expression for the full distorted spectrum arising when the photons of the cosmic background radiation are absorbed and emitted by an optically thin gas. The expression simply adds up the effects of the joint ... More

Correlation of financial markets in times of crisisFeb 07 2011Mar 10 2011Using the eigenvalues and eigenvectors of correlations matrices of some of the main financial market indices in the world, we show that high volatility of markets is directly linked with strong correlations between them. This means that markets tend to ... More

Scalar Resonances in Axially Symmetric SpacetimesMar 12 2015We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that non-axial resonant modes do not exist neither in the Lanczos dust cylinder, the $(2+1)$ extreme BTZ spacetime nor in a class of ... More

Light Cone analysis of relativistic first-order in the gradients hydrodynamicsDec 02 2010This work applies a Rayleigh-Brillouin light spectrum analysis in order to establish a causality test by means of a frequency cone. This technique allows to identify forbidden and unforbidden regions in light scattering experiments and establishes if ... More

On the Statistical Foundations of Kaluza's MagnetohydrodynamicsApr 19 2017The introduction of electromagnetic fields into the Boltzmann equation following a 5D general relativistic approach is considered in order to establish the transport equations for dilute charged fluids in the presence of a weak electromagnetic field. ... More

An internal mechanism for the anti-glitch observed in AXP 1E 2259+586Mar 12 2015Magnetars are fascinating objects that are thought to be neutron stars powered by their strong internal magnetic fields. Clear evidence of a sudden spin-down was detected in the Anomalous X-ray Pulsar AXP 1E 2259+586, an object cataloged as a magnetar. ... More

Oceanic Games: Centralization Risks and Incentives in Blockchain MiningApr 04 2019To participate in the distributed consensus of permissionless blockchains, prospective nodes -- or miners -- provide proof of designated, costly resources. However, in contrast to the intended decentralization, current data on blockchain mining unveils ... More

A convolution integral representation of the thermal Sunyaev-Zel'dovich effectAug 23 2002Feb 27 2003Analytical expressions for the non-relativistic and relativistic Sunyaev-Zel'dovich effect (SZE) are derived by means of suitable convolution integrals. The establishment of these expressions is based on the fact that the SZE disturbed spectrum, at high ... More

Remarks on relativistic kinetic theory to first order in the gradientsJan 20 2009Aug 03 2010In this paper we emphasize some conceptual points related to the kinetic foundations of relativistic hydrodynamics. We summarize previous work and focus on the construction of the heat flux from a kinetic theory point of view. A thorough discussion addressing ... More

Hydrodynamic time correlation functions in the presence of a gravitational fieldJan 24 2003Apr 10 2003This paper shows that the ordinary Brillouin spectrum peaks associated to scattered radiation off acoustic modes in a fluid suffer a shift in their values due to gravitational effects. The approach is based in the ordinary linearized Navier-Stokes equations ... More

Relativistic non-equilibrium thermodynamics revisitedMar 11 2005Mar 16 2005Relativistic irreversible thermodynamics is reformulated following the conventional approach proposed by Meixner in the non-relativistic case. Clear separation between mechanical and non-mechanical energy fluxes is made. The resulting equations for the ... More

Interaction energy functional for lattice density functional theory: Applications to one-, two- and three-dimensional Hubbard modelsNov 20 2003The Hubbard model is investigated in the framework of lattice density functional theory (LDFT). The single-particle density matrix $\gamma_{ij}$ with respect the lattice sites is considered as the basic variable of the many-body problem. A new approximation ... More

Density-matrix functional theory of the Hubbard model: An exact numerical studyOct 18 1999A density functional theory for many-body lattice models is considered in which the single-particle density matrix is the basic variable. Eigenvalue equations are derived for solving Levy's constrained search of the interaction energy functional W, which ... More

Formation of Nanotwin Networks during High-Temperature Crystallization of Amorphous GermaniumJul 14 2015Germanium is an extremely important material used for numerous functional applications in many fields of nanotechnology. In this paper, we study the crystallization of amorphous Ge using atomistic simulations of critical nano-metric nuclei at high temperatures. ... More

Latent Signal Analysis and the Analytic SignalFeb 09 2015Sep 17 2015In this paper we present the latent signal analysis problem as a recasting of the complex extension problem. Almost universally, the approach has been to use the Hilbert Transform (HT) to construct Gabor's analytic signal. This approach depends on harmonic ... More

A causality analysis of the linearized relativistic Navier-Stokes equationsJan 27 2010It is shown by means of a simple analysis that the linearized system of transport equations for a relativistic, single component ideal gas at rest obeys the \textit{antecedence principle}, which is often referred to as causality principle. This task is ... More

Thermodynamics of ultracold trapped gases. Generalized mechanical variables, equation of state and heat capacitySep 27 2008The thermodynamics framework of an interacting quantum gas trapped by an arbitrary external potential is reviewed. We show that for each confining potential, in the thermodynamic limit, there emerge "generalized" volume and pressure variables ${\cal V}$ ... More

Light scattering test regarding the relativistic nature of heatNov 11 2005The dynamic structure factor of a simple relativistic fluid is calculated. The coupling of acceleration with the heat flux present in Eckart's version of irreversible relativistic thermodynamics is examined using the Rayleigh-Brillouin spectrum of the ... More

The Sunyaev-Zel'dovich effect revisitedJul 10 2002Jul 12 2002The well known Sunyaev-Zel'dovich (SZ) effect is reexamined using a Doppler shift type mechanism arising from the scattering of photons by electrons in an optically thin gas. The results are in excellent agreement with the observational data as well as ... More