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Results for "Ignacio Sarasua"

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`Project & Excite' Modules for Segmentation of Volumetric Medical ScansJun 11 2019Jun 12 2019Fully Convolutional Neural Networks (F-CNNs) achieve state-of-the-art performance for image segmentation in medical imaging. Recently, squeeze and excitation (SE) modules and variations thereof have been introduced to recalibrate feature maps channel- ... More
Magnetic transitions in a Double Exchange-Holstein model with e-ph interactions coupled to magnetismFeb 26 2009In this work we study the Double Exchange-Holstein (DE-H) model with an electron-phonon interaction $\gamma$ coupled to magnetism. The analysis is performed combining a mean-field approximation for the double exchange interaction and the Lang-Firsov transformation ... More
`Project & Excite' Modules for Segmentation of Volumetric Medical ScansJun 11 2019Fully Convolutional Neural Networks (F-CNNs) achieve state-of-the-art performance for image segmentation in medical imaging. Recently, squeeze and excitation (SE) modules and variations thereof have been introduced to recalibrate feature maps channel- ... More
On the nature of Be/X-ray binariesJul 15 1998It has been suggested that most Be/X-ray binaries are low X-ray luminosity nearby objects, containing white dwarfs (Chevalier & Ilovaisky 1998). We show that existing evidence indicates that all known Be/X-ray binaries are relatively bright X-ray sources ... More
Stellar wind accretion in high-mass X-ray binariesJul 16 2009Recent discoveries have confirmed the existence of a large population of X-ray sources fuelled by accretion from the stellar wind of an OB supergiant. Such systems are powerful laboratories to study many aspects of astrophysics. Over the last decades, ... More
Secular Light Curve of 2P/Encke: A Comet Active At AphelionJun 12 2008We present the secular light curve of comet 2P/Encke in two phase spaces, the log plot, and the time plot. The main conclusions of this work are: a) The comet shows activity at perihelion and aphelion, caused by two different active areas: Source 1, close ... More
A Search for Luminous Be starsFeb 18 2004As Be stars are restricted to luminosity classes III-V, but early B-type stars are believed to evolve into supergiants, it is to be expected that the Be phenomenon disappears at some point in the evolution of a moderately massive star, before it reaches ... More
Phenomenology of low-scale supersymmetry breaking modelsAug 19 2003In this letter we consider the distinctive phenomenology of supersymmetric models in which the scale of SUSY breaking is very low, \sqrt{F}= O(TeV), focusing on the Higgs sector and the process of electroweak breaking. Using an effective Lagrangian description ... More
Codimension Two Compactifications and the Cosmological Constant ProblemFeb 17 2003We consider solutions of six dimensional Einstein equations with two compact dimensions. It is shown that one can introduce 3-branes in this background in such a way that the effective four dimensional cosmological constant is completely independent of ... More
Cosmic ray electron anisotropies as a tool to discriminate between exotic and astrophysical sourcesMay 11 2009Sep 18 2009Recent results from the PAMELA, ATIC, PPB BETS and Fermi collaborations extend the energy range in the electron flux measurement up to unexplored energies in the hundred GeVs range confirming the bump starting at about 10GeV already suggested by HEAT ... More
The $p\,$-approximation property for simple Lie groups with finite centerSep 24 2016Nov 23 2016We prove that the groups $\text{SL}(3,\mathbb{R})$ and $\text{Sp}(2,\mathbb{R})$ do not have the $p\,$-approximation property for any $1<p<\infty$, which implies in particular that they are not $p\,$-weakly amenable. It follows that the same holds for ... More
Two hard spheres in a pore: Exact Statistical Mechanics for different shaped cavitiesMay 05 2010The Partition function of two Hard Spheres in a Hard Wall Pore is studied appealing to a graph representation. The exact evaluation of the canonical partition function, and the one-body distribution function, in three different shaped pores are achieved. ... More
Binomial canonical decompositions of binomial idealsMar 08 2010May 07 2010In this paper, we prove that every binomial ideal in a polynomial ring over an algebraically closed field of characteristic zero admits a canonical primary decomposition into binomial ideals. Moreover, we prove that this special decomposition is obtained ... More
On squares of cyclic codesMar 03 2017Sep 12 2018The square $C^{*2}$ of a linear error correcting code $C$ is the linear code spanned by the component-wise products of every pair of (non-necessarily distinct) words in $C$. Squares of codes have gained attention for several applications mainly in the ... More
Large-Scale Plant Classification with Deep Neural NetworksJun 12 2017This paper discusses the potential of applying deep learning techniques for plant classification and its usage for citizen science in large-scale biodiversity monitoring. We show that plant classification using near state-of-the-art convolutional network ... More
Can we admit the way in which $\sin(x)$ is typically defined?Aug 28 2015I review some facts which the usual sen(x) and cos(x) definitions are based on. The purpose of this paper is to show that this facts can be proved if we assume some basic ideas of elementary geometry.
The Location of Oort Cloud Comets C/2011 L4 Panstarrs and C/2012 S1 ISON, on a Comets' Evolutionary DiagramJun 20 2013Jun 03 2014We plot the Secular Light Curves (SLCs) of comets C/2011 L4 Panstarrs and C/2012 S1 ISON. The brightness of C/2011 L4 Panstarrs and C/2012 S1 ISON increase steeply after discovery but both decrease in slope sharply at ~4-5 AU, a characteristic of Oort ... More
Clusters rich in red supergiantsMar 15 2018Mar 20 2018In the past few years, several clusters containing large numbers of red supergiants have been discovered. These clusters are amongst the most massive young clusters known in the Milky Way, with stellar masses reaching a few $10^4\:$M$_\odot$. They have ... More
Solutions of an elliptic system with a nearly critical exponentMay 10 2006Consider the problem \begin{eqnarray*} -\Delta u_\e &=& v_\e^p \quad v_\e>0\quad {in}\quad \Omega, -\Delta v_\e &=& u_\e^{q_\e}\quad u_\e>0\quad {in}\quad \Omega, u_\e&=&v_\e\:\:=\:\:0 \quad {on}\quad \partial \Omega, \end{eqnarray*} where $\Omega$ is ... More
Anisotropic finite elements for elliptic problems with singular dataOct 03 2016Jun 27 2017We study the problem $-\Delta u = \gamma$, where $\gamma$ is a singular measure, with support on a curve or a point. We prove that optimal rates of convergence for the finite element method can be obtained using properly graded meshes. In particular, ... More
Multiflavor and multiband observations of neutrinos from core collapse supernovaeFeb 02 2010Apr 02 2010It has been proposed that the gamma ray burst - supernova connection may manifest itself in a significant fraction of core collapse supernovae possessing mildly relativistic jets that do not break out of the stellar envelope. Neutrinos would provide proof ... More
Light Scalar Mesons $σ(500)$, $f_0(980)$ and $κ$ in Charm Meson DecaysAug 23 2002We present recent results on scalar light mesons based on Dalitz plot analyses of charm decays from Fermilab experiment E791. Scalar mesons are found to have large contributions to the decays studied, $D^+\to K^-\pi^+\pi^+$ and $D^+, D_s^+\to\pi^-\pi^+\pi^+$. ... More
Dalitz plot analysis and branching fraction measurement of D+ and Ds+ -> pi+pi-pi+Nov 14 2000Fermilab fixed target experiment E791 obtained a sample of $1172 \pm 61$ events of $D^+ \to \pi^- \pi^+ \pi^+$ and 848 $\pm 44$ events of $D_s^+ \to \pi^- \pi^+ \pi^+$ decays. We find respectively $B (D^+ \to \pi^- \pi^+ \pi^+) / B (D^+ \to K^- \pi^+ ... More
Fluids confined in wedges and by edges: virial series for the line-thermodynamic properties of hard spheresMar 07 2016This work is devoted to analyze the relation between the thermodynamic properties of a confined fluid and the shape of its confining vessel. Recently, new insights in this topic were found through the study of cluster integrals for inhomogeneous fluids, ... More
Radial Schur multipliers on some generalisations of treesMar 18 2018Jul 19 2018We give a characterisation of radial Schur multipliers on finite products of trees. The equivalent condition is that a certain generalised Hankel matrix involving the discrete derivatives of the radial function is a trace class operator. This extends ... More
Reproduction and ferromagnetismJul 10 2013Jul 20 2013I present a stochastic population model that combines cooperative interactions of the type often used in physics with the process of reproduction and death familiar to biology, and I refer to reasons why such interlocking may be of interest to both fields. ... More
The Algebra of Differential Operators for a Gegenbauer Weight MatrixMay 11 2015Dec 30 2015In this paper we study in detail algebraic properties of the algebra $\mathcal D(W)$ of differential operators associated to a matrix weight of Gegenbauer type. We prove that two second order operators generate the algebra, indeed $\mathcal D(W)$ is isomorphic ... More
Anisotropic finite elements for elliptic problems with singular dataOct 03 2016We study the problem $-\Delta u = \sigma$, where $\sigma$ is a singular measure, with support on a curve. In the simplest case, the curve is reduced to a point and $\sigma$ is a Dirac delta distribution. We study the regularity of the solution $u$ in ... More
"Scientist 10 Commandments"Sep 24 2010Feb 28 2014Describes 10 rules that should be followed by scientist.
The $p\,$-approximation property for simple Lie groups with finite centerSep 24 2016Sep 15 2017We prove that, for any $1<p<\infty$, the groups $\text{SL}(3,\mathbb{R})$ and $\text{Sp}(2,\mathbb{R})$ do not have the $p\,$-approximation property of An, Lee and Ruan, which implies in particular that they are not $p\,$-weakly amenable. It follows that ... More
Bending and Gaussian rigidities of confined soft spheres from second-order virial seriesJun 02 2016Aug 30 2016We use virial series to study the equilibrium properties of confined soft-spheres fluids interacting through the inverse-power potentials. The confinement is induced by hard walls with planar, spherical and cylindrical shapes. We evaluate analytically ... More
The Impending Demise of Comet C/2013 US10Sep 20 2015Sep 30 2015We have developed a 3-step criterion to decide if a comet coming from the Oort Cloud will disintegrate. If we apply this criterion to comet C/2013 US10 we find that the probability of disintegration is 92%. The Secular Light Curve of this comet exhibits ... More
The Impending Demise of Comet C/2012 S1 ISONOct 02 2013Oct 03 2013We present evidence to conclude that comet C/2012 S1 ISON is about to turn off or disintegrate.
Binary Matrix Factorization via Dictionary LearningApr 16 2018Jul 26 2018Matrix factorization is a key tool in data analysis; its applications include recommender systems, correlation analysis, signal processing, among others. Binary matrices are a particular case which has received significant attention for over thirty years, ... More
Invariant quadrics and orbits for a family of rational systems of difference equationsNov 13 2013We study the existence of invariant quadrics for a class of systems of difference equations in ${\mathbb R}^n$ defined by linear fractionals sharing denominator. Such systems can be described in terms of some square matrix $A$ and we prove that there ... More
Statistical mechanics of fluids confined by polytopes: The hidden geometry of the cluster integralsMar 14 2013This paper, about a fluid-like system of spatially confined particles, reveals the analytic structure for both, the canonical and grand canonical partition functions. The studied system is inhomogeneously distributed in a region whose boundary is made ... More
The size and mass evolution of the massive galaxies over cosmic timeNov 15 2012Once understood as the paradigm of passively evolving objects, the discovery that massive galaxies experienced an enormous structural evolution in the last ten billion years has opened an active line of research. The most significant pending question ... More
High-mass stars in clusters and associationsSep 12 2011High-mass stars are major players in the chemical and dynamical evolution of galaxies. Open clusters and associations represent the natural laboratories to study their evolution. In this review, I will present a personal selection of current research ... More
Faceted Ranking of Egos in Collaborative Tagging SystemsSep 26 2008Multimedia uploaded content is tagged and recommended by users of collaborative systems, resulting in informal classifications also known as folksonomies. Faceted web ranking has been proved a reasonable alternative to a single ranking which does not ... More
The $p\,$-approximation property for simple Lie groups with finite centerSep 24 2016We prove that the groups $\text{SL}(3,\mathbb{R})$ and $\text{Sp}(2,\mathbb{R})$ do not have the $p\,$-approximation property for any $1<p<\infty$, which implies in particular that they are not $p\,$-weakly amenable. It follows that the same holds for ... More
Be/X-ray binaries: An observational approachNov 12 2004Be/X-ray binaries are the most numerous class of X-ray binaries. They constitute an excellent tracer of star formation and can be used to study several aspects of astrophysics, from mass loss in massive stars to binary evolution. This short review, intended ... More
Spheres, Deficit Angles and the Cosmological ConstantMay 01 2003We consider compactifications of six dimensional gravity in four dimensional Minkowski or de Sitter space times a two dimensional sphere, S^2. As has been recently pointed out, it is possible to introduce 3-branes in these backgrounds with arbitrary tension ... More
Critical Collapse of Collisionless Matter in Spherical SymmetryDec 17 2000We perform a numerical study of the critical regime for the general relativistic collapse of collisionless matter in spherical symmetry. The evolution of the matter is given by the Vlasov equation (or Boltzmann equation) and the geometry by Einstein's ... More
Dark Energy, scalar-curvature couplings and a critical acceleration scaleSep 11 2007We study the effects of coupling a cosmologically rolling scalar field to higher order curvature terms. We show that when the strong coupling scale of the theory is on the 10^{-3}-10^{-1}eV range, the model passes all experimental bounds on the existence ... More
A WN4 companion to BD +62 2296 in Cas OB5Jul 16 2003I report observations of the triple system BD +62 2296 showing that all its components are early-type stars, most likely physically related. The faintest component BD +62 2296B is a hitherto uncatalogued Wolf-Rayet star. The brightest component, star ... More
"Atlas of Secular Light Curves of Comets"Sep 18 2009In this work we have compiled 37,692 observations of 27 periodic and non-periodic comets to create the secular light curves (SLCs), using 2 plots per comet. The data has been reduced homogeneously. Our overriding goal is to learn the properties of the ... More
An equilibrium approach to modelling social interactionJul 15 2009The aim of this work is to put forward a statistical mechanics theory of social interaction, generalizing econometric discrete choice models. After showing the formal equivalence linking econometric multinomial logit models to equilibrium statical mechanics, ... More
Asymptotic behaviour of a semilinear elliptic system with a large exponentMay 11 2006Consider the problem \begin{eqnarray*} -\Delta u &=& v^{\frac 2{N-2}},\quad v>0\quad {in}\quad \Omega, -\Delta v &=& u^{p},\:\:\:\quad u>0\quad {in}\quad \Omega, u&=&v\:\:=\:\:0 \quad {on}\quad \partial \Omega, \end{eqnarray*} where $\Omega$ is a bounded ... More
Fluids confined in wedges and by edges: From cluster integrals to thermodynamic properties referred to different regionsMay 08 2015Jun 25 2015Recently, new insights in the relation between the geometry of the vessel that confines a fluid and its thermodynamic properties were traced through the study of cluster integrals for inhomogeneous fluids. In this work I analyze the thermodynamic properties ... More
Radial continuous rotation invariant valuations on star bodiesMar 20 2015Feb 05 2016We characterize the positive radial continuous and rotation invariant valuations $V$ defined on the star bodies of $\mathbb R^n$ as the applications on star bodies which admit an integral representation with respect to the Lebesgue measure. That is, $$V(K)=\int_{S^{n-1}}\theta(\rho_K)dm,$$ ... More
Three Predictions: Comet 67P/Churyumov-Gerasimenko, Comet C/2012 K1 Panstarrs, and Comet C/2013 V5 OukaimedenMar 07 2014We make the following predictions: (1) Comet 67P/Churyumov-Gerasimenko. The Secular Light Curve (SLC) of this comet exhibits a photometric anomaly in magnitude that is present in 1982, 1996, 2002 and 2009. Thus it must be real. We interpret this anomaly ... More
The starbursts in the Milky WayFeb 13 2014High-mass stars are major players in the chemical and dynamical evolution of galaxies, and young massive clusters are the natural laboratories to study their evolution and their impact on star formation processes. Only in recent years have we become aware ... More
Charmless B decays in modes with similar tree and penguin contributionsAug 21 2014Charmless $B$ decays are dominated by contributions from the short distance amplitudes from tree level and penguin loop-level amplitudes. The Tree contribution presents a weak phase $\gamma$. The relationship between these two amplitudes can generated ... More
Kronecker Square Roots and The Block vec MatrixOct 08 2013Nov 09 2013Using the block vec matrix, I give a necessary and sufficient condition for factorization of a matrix into the Kronecker product of two other matrices. As a consequence, I obtain an elementary algorithmic procedure to decide whether a matrix has a square ... More
Multiplicity, activity and fast rotation in early-type starsJan 16 2006There are obvious and direct ways in which the presence of binary companions may affect activity in OB stars through tidal interactions. In this review, however, I consider a more fundamental role for multiplicity and explore claims that the Be phenomenon ... More
Massive X-ray binaries: New developments in the INTEGRAL eraNov 29 2004The study of massive X-ray binaries provides important observational diagnostics for a number of fundamental astrophysical issues, such as the evolution of massive stars, the stellar winds of massive stars, the formation of compact objects and accretion ... More
Light Scalar Mesons in Charm DecaysJun 28 2002We present recent results on scalar light mesons based on Dalitz plot analyses of charm decays from Fermilab experiment E791. Low mass scalar mesons are found to have large contributions to the decays studied, D^+\to K^-\pi^+\pi^+ and D^+, D_s^+\to\pi^-\pi^+\pi^+. ... More
"Secular Light Curve of Comet 103P/Hartley 2, Target of the EPOXI Mission"Aug 26 2010In support of the EPOXI mission, we have compiled the secular light curve (SLC) of comet 103P/Hartley 2, the next target of EPOXI. a) Of the order of 30 photometric parameters are measured, over 20 of them new. The turn on point of activity is -4.2 +/- ... More
Two hard spheres in a spherical pore: Exact analytic results in two and three dimensionsSep 23 2006Apr 28 2008The partition function and the one- and two-body distribution functions are evaluated for two hard spheres with different sizes constrained into a spherical pore. The equivalent problem for hard disks is addressed too. We establish a relation valid for ... More
Bending rigidity and higher order curvature terms for the hard-sphere fluid near a curved wallNov 20 2013In this work I derive analytic expressions for the curvature dependent fluid-substrate surface tension of a hard sphere fluid on a hard curved wall. In a first step, the curvature thermodynamic properties are found as truncated power series in the activity ... More
Secular Light Curves of Comets C/2011 L4 Panstarrs and C/2012 S1 ISON Compared to 1P/HalleyFeb 19 2013We used 1329 observations of comet C/2011 L4 Panstarrs and 1897 observations of C/2012 S1 ISON to create the Secular Light Curves (SLCs), and to compare them to comet 1P/Halley (3172 observations). These comets are at the present time approaching perihelion. ... More
High-mass stars in Milky Way clustersMar 21 2018Young open clusters are our laboratories for studying high-mass star formation and evolution. Unfortunately, the information that they provide is difficult to interpret, and sometimes contradictory. In this contribution, I present a few examples of the ... More
Reductive locally homogeneous pseudo-Riemannian manifolds and Ambrose-Singer connectionsMay 05 2014Ambrose and Singer characterized connected, simply-connected and complete homogeneous Riemannian manifolds as Riemannian manifolds admitting a metric connection such that its curvature and torsion are parallel. The aim of this paper is to extend Ambrose-Singer ... More
Population genetics of gene functionDec 30 2012May 21 2013This paper shows that differentiating the lifetimes of two phenotypes independently from their fertility can lead to a qualitative change in the equilibrium of a population: since survival and reproduction are distinct functional aspects of an organism, ... More
Heavy meson three body decay: Three decades of Dalitz plot amplitude analysisApr 04 2011Three body heavy meson decays allows one to extract important quantities for flavour physic, however the phenomenological analysis has some open problems to be solved in order to make possible to extract physical parameters with precision. After many ... More
Geometry of the moduli space of $n$-pointed K3 surfaces of genus 11May 15 2017Aug 10 2018We prove that the moduli space of polarized $K3$ surfaces of genus eleven with $n$ marked points is unirational when $n\leq 6$ and uniruled when $n\leq7$. As a consequence, we settle a long standing but not proved assertion about the unirationality of ... More
Uniruledness of Strata of Holomorphic Differentials in Small GenusFeb 22 2017May 28 2018We address the question concerning the birational geometry of the strata of holomorphic and quadratic differentials. We show strata of holomorphic and quadratic differentials to be uniruled in small genus by constructing rational curves via pencils on ... More
Geometrical Structures of Space-Time in General RelativityMar 13 2008Space-Time in general relativity is a dynamical entity because it is subject to the Einstein field equations. The space-time metric provides different geometrical structures: conformal, volume, projective and linear connection. A deep understanding of ... More
Surface density profiles of collisionless disc merger remnantsAug 17 2005Mar 01 2006We present a detailed surface density analysis of a large sample of simulated collisionless mergers of disc galaxies with bulges (mass ratios 1:1, 2:1, 3:1, 4:1, and 6:1) and without bulges (mass ratios 1:1 and 3:1). They were classified, according to ... More
Gravity on codimension 2 brane worldsNov 29 2004We compute the matching conditions for a general thick codimension 2 brane, a necessary previous step towards the investigation of gravitational phenomena in codimension 2 braneworlds. We show that, provided the brane is weakly curved, they are specified ... More
Surface term for the capillary condensation transitions in a slit geometrySep 06 2006It is shown that a bare simple fluid model (SFM) proposed some years ago for studying adsorption between two semi-infinite solid walls can be improved by modifying the surface term in the grand potential for the film phase. Such a correction substantially ... More
An indispensable classification of monomial curves in $\mathbb{A}^4(\mathbbmss{k}) $Mar 24 2011Oct 08 2013In this paper a new classification of monomial curves in $\mathbb{A}^4(\mathbbmss{k})$ is given. Our classification relies on the detection of those binomials and monomials that have to appear in every system of binomial generators of the defining ideal ... More
Band depths based on multiple time instancesMar 27 2017Bands of vector-valued functions $f:T\mapsto\mathbb{R}^d$ are defined by considering convex hulls generated by their values concatenated at $m$ different values of the argument. The obtained $m$-bands are families of functions, ranging from the conventional ... More
An upper bound for the KS-entropy in quantum mixing systemsMar 10 2017We present an upper bound for the Kolmogorov-Sinai entropy of quantum systems having a mixing quantum phase space. The method for this estimation is based on the following ingredients: i) the graininess of quantum phase space in virtue of the Uncertainty ... More
Properties of Quasi-Assouad dimensionMar 07 2017May 11 2017It is shown that for controlled Moran constructions in $\mathbb{R}$, including the (sub) self-similar and more generally, (sub) self-conformal sets, the quasi-Assouad dimension coincides with the upper box dimension. This can be extended to some special ... More
An estimation of the logarithmic timescale in an ergodic dynamicsFeb 25 2017An estimation of the logarithmic timescale in quantum systems having an ergodic dynamics in the semiclassical limit of quasiclassical large parameters, is presented. The estimation is based on the existence of finite generators for ergodic measure-preserving ... More
Lyapunov exponents and Hamiltonian poles in a non Hermitian dynamicsFeb 04 2017By means of expressing volumes in phase space in terms of traces of quantum operators, a relationship between the Hamiltonian poles and the Lyapunov exponents in a non Hermitian quantum dynamics, is presented. We illustrate the formalism by characterizing ... More
Sovereign Default Risk and Uncertainty PremiaDec 22 2015This paper studies how international investors' concerns about model misspecification affect sovereign bond spreads. We develop a general equilibrium model of sovereign debt with endogenous default wherein investors fear that the probability model of ... More
Beyond 31 mag/arcsec^2: the low surface brightness frontier with the largest optical telescopesOct 15 2015Apr 11 2016The detection of optical surface brightness structures in the sky with magnitudes fainter than 30 mag/arcsec^2 (3sigma in 10x10 arcsec boxes; r-band) has remained elusive in current photometric deep surveys. Here we show how present-day 10 meter class ... More
Optimal Taxation with Endogenous Default under Incomplete MarketsAug 17 2015May 07 2016In a dynamic economy, we characterize the fiscal policy of the government when it levies distortionary taxes and issues defaultable bonds to finance its stochastic expenditure. Default may occur in equilibrium as it prevents the government from incurring ... More
On the role of composition entropies in the statistical mechanics of polydisperse systemsJul 01 2014Sep 14 2014Polydisperse systems are commonly encountered when dealing with soft matter in general or any non simple fluid. Yet their treatment within the framework of statistical thermodynamics is a delicate task as the latter has been essentially devised for simple ... More
Torsion-free $G_{2(2)}^*$-structures with full holonomy on nilmanifoldsJul 10 2013Mar 26 2014We study the existence of invariant metrics with holonomy $G_{2(2)}^* \subset SO(4,3)$ on compact nilmanifolds, i.e. on compact quotients of nilpotent Lie groups by discrete subgroups. We prove that, up to isomorphism, there exists only one indecomposable ... More
Pseudo-Kähler Lie algebras with abelian complex structuresJun 15 2012We study Lie algebras endowed with an abelian complex structure which admit a symplectic form compatible with the complex structure. We prove that each of those Lie algebras is completely determined by a pair (U,H) where U is a complex commutative associative ... More
Satellites around massive galaxies since z$\sim$2: confronting the Millennium simulation with observationsMay 16 2012Minor merging has been postulated as the most likely evolutionary path to produce the increase in size and mass observed in the massive galaxies since z$\sim$2. In this Letter, we test directly this hypothesis comparing the population of satellites around ... More
When can quantum decoherence be mimicked by classical noise?Apr 29 2019Quantum decoherence arises due to uncontrollable entanglement between a system with its environment. However the effects of decoherence are often thought of and modeled through a simpler picture in which the role of the environment is to introduce classical ... More
PACO: Global Signal Restoration via PAtch COnsensusAug 20 2018Jun 04 2019Many signal processing algorithms break the target signal into overlapping segments (also called windows, or patches), process them separately, and then stitch them back into place to produce a unified output. At the overlaps, the final value of those ... More
The young open cluster Berkeley 55Dec 02 2011We present UBV photometry of the highly reddened and poorly studied open cluster Berkeley 55, revealing an important population of B-type stars and several evolved stars of high luminosity. Intermediate resolution far-red spectra of several candidate ... More
Is it possible to find the maximum clique in general graphs?Oct 24 2011Feb 17 2012Finding the maximum clique is a known NP-Complete problem and it is also hard to approximate. This work proposes two efficient algorithms to obtain it. Nevertheless, the first one is able to fins the maximum for some special cases, while the second one ... More
Towards a definition of the Quantum Ergodic Hierarchy: Kolmogorov and Bernoulli systemsJan 30 2013Sep 16 2013In this paper we translate the two higher levels of the Ergodic Hierarchy [1], the Kolmogorov level and the Bernoulli level, to quantum language. Moreover, this paper can be considered as the second part of [2]. As in paper [2], we consider the formalism ... More
Deciphering Network Community Structure by SurpriseMay 12 2011Dec 21 2012The analysis of complex networks permeates all sciences, from biology to sociology. A fundamental, unsolved problem is how to characterize the community structure of a network. Here, using both standard and novel benchmarks, we show that maximization ... More
Modeling the Envelope of the Secular Light Curve of the Comete 1P/HalleyMar 18 2011Mar 30 2011We have been modeling the envelope of the secular light curve (Ferr\'in, 2010) of comet 1P/Halley. As the first step we have modeled the water production rate of the comet, for several active regions as a function of visual albedo and infrared albedo, ... More
Quantifying fermionic decoherence in many-body systemsJun 05 2017Practical measures of electronic decoherence, called distilled purities, that are applicable to many-body systems are introduced. While usual measures of electronic decoherence such as the purity employ the full $N$-particle density matrix which is generally ... More
Two moduli spaces of Calabi-Yau typeMay 03 2019We show $\overline{\mathcal{M}}_{10,10}$ and $\mathcal{F}_{11,9}$ have Kodaira dimension zero. Our method utilised the construction of a number of curves via nodal Lefschetz pencils on blown-up $K3$ surfaces which further yield that any effective divisor ... More
Global behaviour of a second order nonlinear difference equationMay 22 2009We describe the asymptotic behaviour and the stability properties of the solutions to a second order rational difference equation.
Superrational typesJan 05 2018We present a formal analysis of Douglas Hofstadter's concept of \emph{superrationality}. We start by defining superrationally justifiable actions, and study them in symmetric games. We then model the beliefs of the players, in a way that leads them to ... More
An exact formalism to study the thermodynamic properties of hard-sphere systems under spherical confinementMar 09 2012Sep 29 2014This paper presents a modified grand canonical ensemble which provides a new simple and efficient scheme to study few-body fluid-like inhomogeneous systems under confinement. The new formalism is implemented to investigate the exact thermodynamic properties ... More
Boosted perturbations at the end of inflationNov 11 2009Jan 26 2010We study the effect on the primordial cosmological perturbations of a sharp transition from inflationary to a radiation and matter dominated epoch respectively. We assume that the perturbations are generated by the vacuum fluctuations of a scalar field ... More
Dielectric branes in non-trivial backgroundsJun 25 2009We present a procedure to evaluate the action for dielectric branes in non-trivial backgrounds. These backgrounds must be capable to be taken into a Kaluza-Klein form, with some non-zero wrapping factor. We derive the way this wrapping factor is gauged ... More
G-Structures defined on pseudo-Riemannian manifoldsOct 31 2008Oct 25 2011Concepts and techniques from the theory of G-structures of higher order are applied to the study of certain structures (volume forms, conformal structures, linear connections and projective structures) defined on a pseudo-Riemanniann manifold. Several ... More
Minimum requirements for laser-induced symmetry breaking in quantum and classical mechanicsJan 24 2008Necessary conditions for generating phase controllable asymmetry in spatially symmetric systems using lasers are identified and are shown to be identical in quantum and classical mechanics. First, by studying the exact dynamics of harmonic systems in ... More