Results for "Silvia Bianchi"

total 2895took 0.13s
Infrared Stability of N=2 Chern-Simons Matter TheoriesDec 22 2009Feb 04 2010According to the AdS4/CFT3 correspondence, N=2 supersymmetric Chern-Simons matter theories should have a stable fixed point in the infrared. In order to support this prediction we study RG flows of two-level Chern-Simons matter theories with/without flavors ... More
Circuits and circulant minorsFeb 08 2019Circulant contraction minors play a key role for characterizing ideal circular matrices in terms of minimally non ideal structures. In this article we prove necessary and sufficient conditions for a circular matrix $A$ to have circulant contraction minors ... More
From Correlators to Wilson Loops in Chern-Simons Matter TheoriesMar 18 2011We study n-point correlation functions for chiral primary operators in three dimensional supersymmetric Chern-Simons matter theories. Our analysis is carried on in N=2 superspace and covers N=2,3 supersymmetric CFT's, the N=6 ABJM and the N=8 BLG models. ... More
The Conformal Manifold of Chern-Simons Matter TheoriesSep 30 2010Oct 25 2010We determine perturbatively the conformal manifold of N=2 Chern-Simons matter theories with the aim of checking in the three dimensional case the general prescription based on global symmetry breaking, recently introduced. We discuss in details few remarkable ... More
Some advances on the set covering polyhedron of circulant matricesMay 28 2012Working on the set covering polyhedron of consecutive ones circulant matrices, Argiroffo and Bianchi found a class of facet defining inequalities, induced by a particular family of circulant minors. In this work we extend these results to inequalities ... More
Minimally helicity violating, maximally simple scalar amplitudes in N=4 SYMAug 01 2012Nov 21 2012In planar N=4 SYM we study a particular class of helicity preserving amplitudes. These are scalar amplitudes whose flavor configuration is chosen in such a way that only a limited number of diagrams is allowed, which exhibit an iterative structure. For ... More
An all order identity between ABJM and N=4 SYM four-point amplitudesDec 15 2011We derive an exact algebraic identity between the two-loop four-point amplitude in ABJM theory and the corresponding one-loop amplitude in N=4 SYM theory. This identity generalizes previous partial results to an exact relation valid at all orders in the ... More
Infrared stability of ABJ-like theoriesOct 27 2009Nov 11 2009We consider marginal deformations of the superconformal ABJM/ABJ models which preserve N=2 supersymmetry. We determine perturbatively the spectrum of fixed points and study their infrared stability. We find a closed line of fixed points which is IR stable. ... More
Homotopy type of symplectomorphism groups of S^2 X S^2Sep 25 2000May 02 2002In this paper we discuss the topology of the symplectomorphism group of a product of two 2-dimensional spheres when the ratio of their areas lies in the interval (1,2]. More precisely we compute the homotopy type of this symplectomorphism group and we ... More
Finite dimensional representations of symplectic reflection algebras associated to wreath products IIJan 11 2005This note extends some results of a previous paper (math.RT/0403250) about finite dimensional representations of the wreath product symplectic reflection algebra H(k,c,N,G) of rank N attached to a finite subgroup G of SL(2,C) (here k is a number and c ... More
On the Chern numbers and the Hilbert polynomial of an almost complex manifold with a circle actionNov 24 2014Feb 15 2016Let $(M,J)$ be a compact, connected, almost complex manifold of dimension $2n$ endowed with a $J$-preserving circle action with isolated fixed points. In this note we analyse the `geography problem' for such manifolds, deriving equations relating the ... More
Nonlinear Dirichlet problem for the nonlocal anisotropic operator $L_K$May 29 2018Sep 28 2018In this paper we study an equation driven by a nonlocal anisotropic operator with homogeneous Dirichlet boundary conditions. We find at least three non trivial solutions: one positive, one negative and one of unknown sign, using variational methods and ... More
Modelling the Far-Infrared emission in spyral galaxiesNov 22 1999This thesis presents an original model for the FIR emission in spirals, developed from an existing radiative transfer code (Bianchi, Ferrara & Giovanardi, 1996, ApJ, 465, 127). The model's main features are: a complete treatment of multiple scattering ... More
Dust Extinction and Emission in a Clumpy Galactic Disk. An Application of the Radiative Transfer Code TRADINGJul 18 2008Jul 24 2008AIMS: I present the Monte Carlo radiative transfer code TRADING (Transfer of RAdiation through Dust In Galaxies). The code computes self-consistently the extinction of radiation in a dusty medium (including absorption and scattering) and the dust emission. ... More
Black hole entropy from graviton entanglementNov 02 2012Jan 07 2013We argue that the entropy of a black hole is due to the entanglement of matter fields and gravitons across the horizon. While the entanglement entropy of the vacuum is divergent because of UV correlations, we show that low-energy perturbations of the ... More
Black Hole Entropy, Loop Gravity, and Polymer PhysicsNov 25 2010Loop Gravity provides a microscopic derivation of Black Hole entropy. In this paper, I show that the microstates counted admit a semiclassical description in terms of shapes of a tessellated horizon. The counting of microstates and the computation of ... More
The covariogram and Fourier-Laplace transform in $\mathbb{C}^n$Dec 30 2013Apr 29 2016The covariogram $g_{K}$ of a convex body $K$ in $\mathbb{R}^n$ is the function which associates to each $x\in\mathbb{R}^n$ the volume of the intersection of $K$ with $K+x$. Determining $K$ from the knowledge of $g_K$ is known as the Covariogram Problem. ... More
Lovász-Schrijver PSD-operator on Claw-Free GraphsDec 06 2016The subject of this work is the study of $\LS_+$-perfect graphs defined as those graphs $G$ for which the stable set polytope $\stab(G)$ is achieved in one iteration of Lov\'asz-Schrijver PSD-operator $\LS_+$, applied to its edge relaxation $\estab(G)$. ... More
On dominating set polyhedra of circular interval graphsDec 19 2017Feb 20 2018Clique-node and closed neighborhood matrices of circular interval graphs are circular matrices. The stable set polytope and the dominating set polytope on these graphs are therefore closely related to the set packing polytope and the set covering polyhedron ... More
Light-like Wilson loops in ABJM and maximal transcendentalityApr 22 2013We revisit the computation of the two-loop light-like tetragonal Wilson loop for three dimensional pure Chern-Simons and N=6 Chern-Simons-matter theory, within dimensional regularization with dimensional reduction scheme. Our examination shows that, contrary ... More
The 1/2 BPS Wilson loop in ABJM theory at two loopsMar 27 2013We compute the expectation value of the 1/2 BPS circular Wilson loop in ABJM theory at two loops in perturbation theory. The result shows perfect agreement with the prediction from localization and the proposed framing factor.
The 1/2 BPS Wilson loop in ABJ(M) at two loops: The detailsJul 02 2013Jul 14 2013We compute the expectation value of the 1/2 BPS circular Wilson loop operator in ABJ(M) theory at two loops in perturbation theory. Our result turns out to be in exact agreement with the weak coupling limit of the prediction coming from localization, ... More
A combinatorial approach to Alexander-Hirschowitz Theorem based on toric degenerationsJul 21 2009May 26 2010We present an alternative proof of the Alexander-Hirschowitz Theorem in dimension 3 using degenerations of toric varieties.
Glass transition of an epoxy resin induced by temperature, pressure and chemical conversion: a configurational entropy rationaleJun 25 2001A comparative study is reported on the dynamics of a glass-forming epoxy resin when the glass transition is approached through different paths: cooling, compression, and polymerization. In particular, the influence of temperature, pressure and chemical ... More
Maximum Principle for Linear-Convex Boundary Control Problems applied to Optimal Investment with Vintage CapitalNov 23 2007The paper concerns the study of the Pontryagin Maximum Principle for an infinite dimensional and infinite horizon boundary control problem for linear partial differential equations. The optimal control model has already been studied both in finite and ... More
Equilibrium points for Optimal Investment with Vintage CapitalDec 01 2007The paper concerns the study of equilibrium points, namely the stationary solutions to the closed loop equation, of an infinite dimensional and infinite horizon boundary control problem for linear partial differential equations. Sufficient conditions ... More
Umbral Calculus, a Different Mathematical LanguageFeb 24 2018This thesis is intended to provide an account of the theory and applications of Operational Methods that allow the "translation" of the theory of special functions and polynomials into a "different" mathematical language. The language we are referring ... More
Nonanticommutative U(1) SYM theories: Renormalization, fixed points and infrared stabilityApr 21 2009Renormalizable nonanticommutative SYM theories with chiral matter in the adjoint representation of the gauge group have been recently constructed in [arXiv:0901.3094]. In the present paper we focus on the U*(1) case with matter interacting through a cubic ... More
Gravitational lensing on the Cosmic Microwave Background by gravity wavesAug 21 1997We study the effect of a stochastic background of gravitational waves on the gravitational lensing of the Cosmic Microwave Background (CMB) radiation. It has been shown that matter density inhomogeneities produce a smoothing of the acoustic peaks in the ... More
The Minor inequalities in the description of the Set Covering Polyhedron of Circulant MatricesJun 06 2012In this work we give a complete description of the set covering polyhedron of circulant matrices $C^k_{sk}$ with $s = 2,3$ and $k\geq 3 $ by linear inequalities. In particular, we prove that every non boolean facet defining inequality is associated with ... More
Vindicating single-T modified blackbody fits to Herschel SEDs (Research Note)Feb 22 2013I show here that the bulk of the dust mass in a galaxy can be equivalently estimated from: i) the full spectral energy distribution of dust emission, using the approach of Draine & Lee (2007) that includes a distribution of dust grains and a range of ... More
The dust distribution in edge-on galaxies. Radiative transfer fits of V and K'-band imagesMay 10 2007Aims: I have analyzed a sample of seven nearby edge-on galaxies observed in the V and K'-band, in order to infer the properties of the dust distribution. Methods: A radiative transfer model, including scattering, have been used to decompose each image ... More
Ergodic convergence of a stochastic proximal point algorithmApr 21 2015Jul 25 2016The purpose of this paper is to establish the almost sure weak ergodic convergence of a sequence of iterates $(x_n)$ given by $x_{n+1} = (I+\lambda_n A(\xi_{n+1},\,.\,))^{-1}(x_n)$ where $(A(s,\,.\,):s\in E)$ is a collection of maximal monotone operators ... More
Entropy of Non-Extremal Black Holes from Loop GravityApr 23 2012We compute the entropy of non-extremal black holes using the quantum dynamics of Loop Gravity. The horizon entropy is finite, scales linearly with the area A, and reproduces the Bekenstein-Hawking expression S = A/4 with the one-fourth coefficient for ... More
Perturbation theory for string sigma modelsApr 06 2016Apr 07 2016In this thesis we investigate quantum aspects of the Green-Schwarz superstring in various AdS backgrounds relevant for the AdS/CFT correspondence, providing several examples of perturbative computations in the corresponding integrable sigma-models. We ... More
Splitting of the homology of the punctured mapping class groupMar 14 2019Let $\Gamma_{g,1}^m$ be the mapping class group of the orientable surface $\Sigma_{g,1}^m$ of genus $g$ with one parametrised boundary curve and $m$ permutable punctures; when $m=0$ we omit it from the notation. Let $\beta_{m}(\Sigma_{g,1})$ be the braid ... More
Quadratic Chabauty for (bi)elliptic curves and Kim's conjectureApr 09 2019We explore a number of problems related to the quadratic Chabauty method for determining integral points on hyperbolic curves. We remove the assumption of semistability in the description of the quadratic Chabauty sets $\mathcal{X}(\mathbb{Z}_p)_2$ containing ... More
The cross covariogram of a pair of polygons determines both polygons, with a few exceptionsMay 13 2008The cross covariogram g_{K,L} of two convex sets K and L in R^n is the function which associates to each x in R^n the volume of the intersection of K and L+x. Very recently Averkov and Bianchi [AB] have confirmed Matheron's conjecture on the covariogram ... More
Radiative Transfer in Spiral GalaxiesSep 16 2003The internal dust extinction in spiral galaxies can affect our understanding of their structure and morphology, as well as our perception of the distant universe in the background. The intrinsic properties of the stellar and dust components can be studied ... More
On R^4 terms and MHV amplitudes in N = 5,6 supergravity vacua of Type II superstringsOct 22 2010We compute one-loop threshold corrections to R^4 terms in N= 5,6 supergravity vacua of Type II superstrings. We then discuss non-perturbative corrections generated by asymmetric D-brane instantons. Finally we derive generating functions for MHV amplitudes ... More
Higher spin symmetry (breaking) in N=4 SYM theory and holographySep 29 2004I concisely review the results of recent work done in collaboration with N. Beisert, H. Samtleben, and J. F. Morales, that shed some light on ``La Grande Bouffe'', the Pantagruelic Higgs mechanism whereby higher spin gauge fields in the AdS bulk eat lower ... More
The covariogram determines three-dimensional convex polytopesMay 12 2008The cross covariogram g_{K,L} of two convex sets K, L in R^n is the function which associates to each x in R^n the volume of the intersection of K with L+x. The problem of determining the sets from their covariogram is relevant in stochastic geometry, ... More
Quantum dispersion relations for the $AdS_4 \times CP^3$ GKP stringMay 04 2015Nov 04 2015We compute the one-loop correction to the dispersion relations of the excitations of the $AdS_4 \times CP^3$ sigma model dual to ABJM theory, expanded around the cusp background. The results parallel those of N = 4 SYM. As in that case, the dispersion ... More
Modeling and Querying Data Cubes on the Semantic WebDec 18 2015The web is changing the way in which data warehouses are designed, used, and queried. With the advent of initiatives such as Open Data and Open Government, organizations want to share their multidimensional data cubes and make them available to be queried ... More
Approximate likelihood inference in generalized linear latent variable models based on integral dimension reductionMar 04 2015Latent variable models represent a useful tool for the analysis of complex data when the constructs of interest are not observable. A problem related to these models is that the integrals involved in the likelihood function cannot be solved analytically. ... More
Optimization Modulo Theories with Linear Rational CostsOct 22 2014In the contexts of automated reasoning (AR) and formal verification (FV), important decision problems are effectively encoded into Satisfiability Modulo Theories (SMT). In the last decade efficient SMT solvers have been developed for several theories ... More
Cosmic Microwave Background anisotropies from second order gravitational perturbationsFeb 27 1997Jul 10 1997This paper presents a complete analysis of the effects of second order gravitational perturbations on Cosmic Microwave Background anisotropies, taking explicitly into account scalar, vector and tensor modes. We also consider the second order perturbations ... More
An integer optimization problem for non-Hamiltonian periodic flowsJul 25 2013Let C be the class of compact 2n-dimensional symplectic manifolds M for which the first or (n-1) Chern class vanish. We point out an integer optimization problem to find a lower bound B(n) on the number of equilibrium points of non-Hamiltonian symplectic ... More
A Polygonal Discontinuous Galerkin Method with Minus One StabilizationMay 10 2018We propose an Hybridized Discontinuous Galerkin method on polygonal tessellation, with a stabilization term penalizing locally in each element $K$ a residual term involving the fluxes in the norm of the dual of $H^1(K)$. The scalar product corresponding ... More
Ultra-high energy cosmic rays from a nearby extragalactic source in the diffusive regimeMar 13 2019We study the effects that the diffusion of the cosmic rays in the magnetic field of the Local Supercluster can have on the spectrum of a nearby extragalactic source at ultra-high energies. We find that the strong enhancement of the flux below the energy ... More
Kicked neutron stars and microlensingSep 02 1996Due to the large kick velocities with which neutron stars are born in supernovae explosions, their spatial distribution is more extended than that of their progenitor stars. The large scale height of the neutron stars above the disk plane makes them potential ... More
Progress in high-energy cosmic ray physicsOct 30 2017We review some of the recent progress in our knowledge about high-energy cosmic rays, with an emphasis on the interpretation of the different observational results. We discuss the effects that are relevant to shape the cosmic ray spectrum and the explanations ... More
Logarithmic growth of entanglement entropy in out-of-equilibrium long-range systemsNov 13 2018In this work, we derive the analytical relation between bipartite entanglement entropy and collective spin-squeezing in long-range spin systems in and out of equilibrium, and use it to elucidate the mechanism responsible for the logarithmic growth in ... More
Complex and strongly anisotropic magnetism in the pure spin system EuRh2Si2Nov 03 2013In divalent Eu systems, the 4f local moment has a pure spin state J=S=7/2. Although the absence of orbital moment precludes crystal electric field effects, we report a sizeable magnetic anisotropy in single crystals of EuRh2Si2. We observed a surprisingly ... More
The stochastic gravitational-wave background produced by non-linear cosmological perturbationsMay 21 1997The cosmological stochastic gravitational-wave background produced by the mildly non-linear evolution of density fluctuations is analyzed, in the frame of an Einstein-de Sitter model, by means of a fully relativistic perturbation expansion up to second ... More
Finite dimensional representations of symplectic reflection algebras associated to wreath productsMar 15 2004Jun 09 2004In this paper we construct finite dimensional representations of the wreath product symplectic reflection algebra H(k,c,N,G) of rank N attached to a finite subgroup G of SL(2,C) (here k is a number and c a class function on the set of nontrivial elements ... More
Cocharacters of polynomial identities of upper triangular matricesJan 24 2011We give an easy algorithm which calculates the generating function of the cocharacter sequence of the T-ideal of the polynomial identities of the algebra of upper triangular matrices over a field of characteristic zero. Applying this algorithm we have ... More
Operators ideals and approximation propertiesNov 30 2012Dec 13 2012We use the notion of $\A$-compact sets, which are determined by a Banach operator ideal $\A$, to show that most classic results of certain approximation properties and several Banach operator ideals can be systematically studied under this framework. ... More
Generic expansions of countable modelsOct 31 2010Jan 20 2012We compare two different notions of generic expansions of countable saturated structures. One kind of genericity is related to model-companions and to amalgamation constructions \'a la Hrushovski-Fra\"iss\'e. Another notion of generic expansion is defined ... More
A Direct Proof of Schwichtenberg's Bar Recursion Closure TheoremJul 18 2016In 1979 Schwichtenberg showed that a rule-like version Spector's bar recursion of lowest type levels $0$ and $1$ is closed under system $\text{T}$. More precisely, if the functional $Y$ which controls the stopping condition of Spector's bar recursor is ... More
Generic Large Cardinals and Systems of FiltersNov 17 2015We introduce the notion of $\mathcal{C}$-system of filters, generalizing the standard definitions of both extenders and towers of normal ideals. This provides a framework to develop the theory of extenders and towers in a more general and concise way. ... More
Summary of WG6: Spin PhysicsAug 30 2016The working group on Spin Physics at the XXIV International Workshop on Deep-Inelastic Scattering and Related Subjects (DIS2016) witnessed a significant progress in the theoretical and experimental investigations aiming at unveiling the innermost structure ... More
Analysis and approximation of some Shape-from-Shading models for non-Lambertian surfacesFeb 18 2015Jan 27 2016The reconstruction of a 3D object or a scene is a classical inverse problem in Computer Vision. In the case of a single image this is called the Shape-from-Shading (SfS) problem and it is known to be ill-posed even in a simplified version like the vertical ... More
Evaluation of two interaction techniques for visualization of dynamic graphsAug 31 2016Several techniques for visualization of dynamic graphs are based on different spatial arrangements of a temporal sequence of node-link diagrams. Many studies in the literature have investigated the importance of maintaining the user's mental map across ... More
A unified approach to the well-posedness of some non-Lambertian models in Shape-from-Shading theoryMar 21 2016Oct 04 2016In this paper we show that the introduction of an attenuation factor in the %image irradiance brightness equations relative to various perspective Shape from Shading models allows to make the corresponding differential problems well-posed. We propose ... More
Fractional Cable Model for Signal Conduction in Spiny Neuronal DendritesFeb 17 2017The cable model is widely used in several fields of science to describe the propagation of signals. A relevant medical and biological example is the anomalous subdiffusion in spiny neuronal dendrites observed in several studies of the last decade. Anomalous ... More
Numerical evidence of Sinai diffusion of random-mass Dirac particlesDec 27 2016We present quantum Lattice Boltzmann simulations of the Dirac equation for quantum-relativistic particles with random mass. By choosing zero-average random mass fluctuation, the simulations show evidence of localization and ultra-slow Sinai diffusion, ... More
A multidimensional latent class IRT model for non-ignorable missing responsesOct 17 2014We propose a structural equation model, which reduces to a multidimensional latent class item response theory model, for the analysis of binary item responses with non-ignorable missingness. The missingness mechanism is driven by two sets of latent variables: ... More
Bayesian inference for a class of latent Markov models for categorical longitudinal dataJan 02 2011Jan 04 2011We propose a Bayesian inference approach for a class of latent Markov models. These models are widely used for the analysis of longitudinal categorical data, when the interest is in studying the evolution of an individual unobservable characteristic. ... More
On the structure of graphs with given odd girth and large minimum degreeFeb 11 2016Mar 14 2016We study minimum degree conditions for which a graph with given odd girth has a simple structure. For example, the classical work of Andr\'asfai, Erd\H os, and S\'os implies that every $n$-vertex graph with odd girth $2k+1$ and minimum degree bigger than ... More
New convergence results for the scaled gradient projection methodJun 25 2014Feb 26 2015The aim of this paper is to deepen the convergence analysis of the scaled gradient projection (SGP) method, proposed by Bonettini et al. in a recent paper for constrained smooth optimization. The main feature of SGP is the presence of a variable scaling ... More
Automorphisms of trivalent graphsNov 15 2011Let $G_{g,b}$ be the set of all uni/trivalent graphs representing the combinatorial structures of pant decompositions of the oriented surface of genus $g$ with $b$ boundary components. We describe the set $A_{g,b}$ of all automorphisms of graphs in $G_{g,b}$ ... More
Convergence of a Multi-Agent Projected Stochastic Gradient Algorithm for Non-Convex OptimizationJul 13 2011Dec 02 2013We introduce a new framework for the convergence analysis of a class of distributed constrained non-convex optimization algorithms in multi-agent systems. The aim is to search for local minimizers of a non-convex objective function which is supposed to ... More
The Blaschke-Santalo InequalityDec 01 2013Aug 04 2014The Blaschke-Santal\'o Inequality is the assertion that the volume product of a centrally symmetric convex body in Euclidean space is maximized by (and only by) ellipsoids. In this paper we give a Fourier analytic proof of this fact.
Horizon energy as the boost boundary term in general relativity and loop gravityMay 24 2012We show that the near-horizon energy introduced by Frodden, Ghosh and Perez arises from the action for general relativity as a horizon boundary term. Spin foam variables are used in the analysis. The result provides a derivation of the horizon boost Hamiltonian ... More
The quantum 1/2 BPS Wilson loop in ${\cal N}=4$ Chern-Simons-matter theoriesJun 22 2016In three dimensional ${\cal N}=4$ Chern-Simons-matter theories two independent fermionic Wilson loop operators can be defined, which preserve half of the supersymmetry charges and are cohomologically equivalent at classical level. We compute their three-loop ... More
A matrix model for the latitude Wilson loop in ABJM theoryFeb 21 2018Aug 13 2018In ABJ(M) theory, we propose a matrix model for the exact evaluation of BPS Wilson loops on a latitude circular contour, so providing a new weak-strong interpolation tool. Intriguingly, the matrix model turns out to be a particular case of that computing ... More
One Loop Amplitudes In ABJMApr 19 2012Jul 10 2012For three dimensional N=6 superconformal field theories we compute one-loop scattering amplitudes for any number of external particles. We focus on a particular subsector of N=2 invariant superamplitudes for which the ordinary perturbative evaluation ... More
Scattering Amplitudes/Wilson Loop Duality In ABJM TheoryJul 15 2011Oct 05 2011For N=6 superconformal Chern-Simons-matter theories in three dimensions, by a direct superspace Feynman diagram approach, we compute the two-loop four-point scattering amplitude with external chiral matter fields. We find that the result is in perfect ... More
Cosmic Microwave Background non-Gaussian signatures from analytical texture modelsJan 12 1996Jul 22 1996Using an analytical model for the Cosmic Microwave Background anisotropies produced by textures, we compute the resulting collapsed three--point correlation function and the {\it rms} expected value due to the cosmic variance. We apply our calculations ... More
On p-Compact mappings and p-approximationJul 08 2011Aug 04 2011The notion of $p$-compact sets arises naturally from Grothendieck's characterization of compact sets as those contained in the convex hull of a norm null sequence. The definition, due to Sinha and Karn (2002), leads to the concepts of $p$-approximation ... More
A dynamical model of the adaptive immune system: effects of cells promiscuity, antigens and B-B interactionsMay 14 2015We analyse a minimal model for the primary response in the adaptive immune system comprising three different players: antigens, T and B cells. We assume B-T interactions to be diluted and sampled locally from heterogeneous degree distributions, which ... More
Associative networks with diluted patterns: dynamical analysis at low and medium loadMay 10 2014In this work we solve the dynamics of pattern diluted associative networks, evolving via sequential Glauber update. We derive dynamical equations for the order parameters, that quantify the simultaneous pattern recall of the system, and analyse the nature ... More
A new method to search for a cosmic ray dipole anisotropyApr 28 2005We propose a new method to determine the dipole (and quadrupole) component of a distribution of cosmic ray arrival directions, which can be applied when there is partial sky coverage and/or inhomogeneous exposure. In its simplest version it requires that ... More
Generic Large Cardinals and Systems of FiltersNov 17 2015Apr 05 2017We introduce the notion of $\mathcal{C}$-system of filters, generalizing the standard definitions of both extenders and towers of normal ideals. This provides a framework to develop the theory of extenders and towers in a more general and concise way. ... More
On fixed point sets and Lefschetz modules for sporadic simple groupsFeb 16 2008We consider 2-local geometries and other subgroup complexes for sporadic simple groups. For six groups, the fixed point set of a noncentral involution is shown to be equivariantly homotopy equivalent to a standard geometry for the component of the centralizer. ... More
On fixed point sets of distinguished collections for groups of parabolic characteristicNov 27 2007Nov 27 2007We determine the nature of the fixed point sets of groups of order p, acting on complexes of distinguished p-subgroups (those p-subgroups containing p-central elements in their centers). The case when G has parabolic characteristic p is analyzed in detail. ... More
On a homotopy relation between the 2-local geometry and the Bouc complex for the sporadic group Co3Oct 26 2005Nov 27 2007We study the homotopy relation between the standard 2-local geometry and the Bouc complex for the sporadic group Co3. We also give a result concerning the relative projectivity of the reduced Lefschetz module associated to the aformentioned 2-local geometry. ... More
Algebraic Properties of Codimension Series of PI-AlgebrasNov 01 2011For a PI-algebra R over a field of characteristic 0 let T(R) be the T-ideal of the polynomial identities of R and let c(R,t) be the codimension series of R (i.e., the generating function of the codimension sequence of R). Let A, B and R be PI-algebras ... More
Canonical bases for the equivariant cohomology and K-theory rings of symplectic toric manifoldsMar 16 2015Let $M$ be a symplectic toric manifold acted on by a torus $\mathbb{T}$. In this work we exhibit an explicit basis for the equivariant K-theory ring $\mathcal{K}_{\mathbb{T}}(M)$ which is canonically associated to a generic component of the moment map. ... More
Structured conditioning of Hamiltonian eigenvalue problemsMay 21 2012We discuss the effect of structure-preserving perturbations on complex or real Hamiltonian eigenproblems and characterize the structured worst-case effect perturbations. We derive significant expressions for both the structured condition numbers and the ... More
The complex of pant decompositions of a surfaceOct 08 2007Oct 27 2007We exhibit a set of edges (moves) and 2-cells (relations) making the complex of pant decompositions on a surface a simply connected complex. Our construction, unlike the previous ones, keeps the arguments concerning the structural transformations independent ... More
BPS Wilson loops and Bremsstrahlung function in ABJ(M): a two loop analysisFeb 17 2014Mar 11 2014We study a family of circular BPS Wilson loops in N=6 super Chern-Simons-matter theories, generalizing the usual 1/2-BPS circle. The scalar and fermionic couplings depend on two deformation parameters and these operators can be considered as the ABJ(M) ... More
Big Data Computing and Clouds: Trends and Future DirectionsDec 17 2013Aug 22 2014This paper discusses approaches and environments for carrying out analytics on Clouds for Big Data applications. It revolves around four important areas of analytics and Big Data, namely (i) data management and supporting architectures; (ii) model development ... More
Attractive forces between circular polyions of the same chargeDec 19 2001We study two models of ringlike polyions which are two-dimensional versions of simple models for colloidal particles (model A) and for rodlike segments of DNA (model B), both in solution with counterions. The counterions may condensate on Z sites of the ... More
Notes on projective normality of reducible curvesSep 24 2010We give some results on quadratic normality of reducible curves canonically embedded and partially extend this study to their projective normality.
The nonminimal scalar multiplet coupled to supersymmetric Yang-MillsDec 15 1997We consider the coupling of nonminimal scalar multiplets to supersymmetric Yang-Mills in four dimensions and compute the one-loop contribution to the low-energy effective action in the abelian sector. We show that the resulting theory realizes the dual ... More
Domain wall flow equations and SU(3)xSU(3) structure compactificationsMay 11 2009Nov 30 2009We study supersymmetric domain wall solutions in four dimensions arising from the compactification of type II supergravity on a SU(3)xSU(3) structure manifold. Using a pure spinor approach, we show that the supersymmetry variations can be reinterpreted ... More
Orbital degrees of freedom as origin of magnetoelectric coupling in magnetiteOct 06 2010Oct 07 2010A microscopic understanding of magnetoelectricity, i.e. the coupling between magnetic (electric) properties and external electric (magnetic) fields, is a crucial milestone for future generations of electrically-controlled spintronic devices. Here, we ... More
Fast nonnegative least squares through flexible Krylov subspacesNov 19 2015Jan 06 2017Constrained least squares problems arise in a variety of applications, and many iterative methods are already available to compute their solutions. This paper proposes a new efficient approach to solve nonnegative linear least squares problems. The associated ... More