Results for "Jacopo Fumagalli"

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Renormalization Group independence of Cosmological AttractorsNov 15 2016The large class of inflationary models known as $\alpha$- and $\xi$-attractors give identical predictions at tree level (at leading order in inverse power of the number of efolds). Working with the renormalization group improved action, we show that these ... More
UV (in)sensitivity of Higgs inflationFeb 23 2016Apr 27 2016The predictions of Standard Model Higgs inflation are in excellent agreement with the Planck data, without the need for new fields. However, consistency of the theory requires the presence of (unknown) threshold corrections. These modify the running of ... More
Tensor power spectrum and disformal transformationsOct 26 2016In a general effective theory description of inflation a disformal transformation can be used to set the tensor sound speed to one. After the transformation, the tensor power spectrum then automatically only depends on the Hubble parameter. We show that ... More
Non-local formulation of ghost-free bigravity theoryJul 21 2014We study the ghost-free bimetric theory of Hassan and Rosen, with parameters $\beta_i$ such that a flat Minkowski solution exists for both metrics. We show that, expanding around this solution and eliminating one of the two metrics with its own equation ... More
A free-boundary problem with moving contact pointsJul 01 2017This paper concerns the theoretical and numerical analysis of a free boundary problem for the Laplace equation, with a curvature condition on the free boundary. This boundary is described as the graph of a function, and contact angles are imposed at the ... More
Metal abundances in the high-redshift intergalactic mediumDec 18 2013Twenty years of high-resolution spectroscopy at the 8-10 m class telescopes have drastically expanded our view of the gas-phase metallicity in the z>2 universe. This contribution briefly summarizes how these studies reveal a widespread metal pollution ... More
Instantons and quark zero modes in AdS/QCDSep 16 2009In this paper the quark zero modes creation effect is studied in the context of the AdS/QCD approach. This effect is generated, in presence of instantons, by a new that can be added in the bulk.
Framed symplectic sheaves on surfacesApr 05 2016Apr 28 2016A framed symplectic sheaf on a smooth projective surface $X$ is a torsion-free sheaf $E$ together with a trivialization on a divisor $D\subseteq X$ and a morphism $\Lambda^{2}E\rightarrow\mathcal{O}_{X}$ satisfying some additional conditions. We construct ... More
A generalisation of a theorem of WielandtAug 16 2016In 1974, Helmut Wielandt proved that in a finite group $G$, a subgroup $A$ is subnormal if and only if it is subnormal in every $\seq{A,g}$ for all $g\in G$. In this paper, we prove that the subnormality of an odd order nilpotent subgroup $A$ of $G$ is ... More
On the class of continuous images of non-commutative Valdivia compactaMar 11 2016We investigate the class of continuous images of non-commutative Valdivia compact spaces, in particular its subclass of weakly non-commutative Cor- son countably compact spaces. A key tool is the study of non-commutative Corson countably compact spaces ... More
Comments on the Chiral Symmetry Breaking in Soft Wall Holographic QCDDec 14 2009Dec 23 2009In this paper we describe qualitatively some aspects of the holographic QCD. Inspired by a successfull 4D description, we try to separate the Confinement and the Chiral Symmetry Breaking dynamics. We also discuss the realization of the baryons as skyrmions ... More
Unstable BlowupsFeb 06 2007Nov 12 2007Let (X,L) be a polarised manifold. We show that K-stability and asymptotic Chow stability of the blowup of X along a 0-dimensional cycle are closely related to Chow stability of the cycle itself, for polarizations making the exceptional divisors small. ... More
On compact trees with the coarse wedge topologyMar 29 2018Jan 15 2019In the present paper we investigate the class of compact trees, endowed with the coarse wedge topology, in the area of non-separable Banach spaces. We describe Valdivia compact trees in terms of inner structures and we characterize the space of continuous ... More
On the local cartesian closure of exact completionsApr 23 2018A characterisation of cartesian closure of exact completions as a property of the projective objects was given by Carboni and Rosolini. We show that the argument used to prove that characterisation is equivalent to the projectives being closed under binary ... More
The Fullness Axiom and exact completions of homotopy categoriesAug 29 2018We use a category-theoretic formulation of Aczel's Fullness Axiom from Constructive Set Theory to derive the local cartesian closure of an exact completion. As an application, we prove that such a formulation is valid in the homotopy category of any model ... More
On $C^*$-algebras associated to actions of discrete subgroups of $SL(2,\mathbb{R})$ on $\mathbb{R}^2 \backslash \{0\}$Jun 23 2018Dynamical conditions that guarantee stability for discrete transformation group $C^*$-algebras are determined. The results are applied to the case of some discrete subgroups of $SL(2,\mathbb{R})$ acting on the plane with the origin removed by means of ... More
Universal covers and the GW/Kronecker correspondenceNov 22 2010Nov 28 2011The tropical vertex is an incarnation of mirror symmetry found by Gross, Pandharipande and Siebert. It can be applied to m-Kronecker quivers K(m) (together with a result of Reineke) to compute the Euler characteristics of the moduli spaces of their (framed) ... More
Statistical Hadronization and HolographyDec 14 2009Dec 17 2009In this paper we consider some issues about the statistical model of the hadronization in a holographic approach. We introduce a Rindler like horizon in the bulk and we understand the string breaking as a tunneling event under this horizon. We calculate ... More
QCD condensates in ADS/QCDSep 25 2009This paper focuses on some issues about condensates and renormalization in AdS/QCD models. In particular we consider the consistency of the AdS/QCD approach for scale dependent quantities as the chiral condensate questioned in some recent papers and the ... More
Krylov Iterative Methods for the Geometric Mean of Two Matrices Times a VectorMar 04 2019In this work, we are presenting an efficient way to compute the geometric mean of two positive definite matrices times a vector. For this purpose, we are inspecting the application of methods based on Krylov spaces to compute the square root of a matrix. ... More
D0-D6 states counting and GW invariantsDec 15 2009We describe a correspondence between the virtual number of torsion free sheaves locally free in codimension 3 on a Calabi-Yau 3-fold and the Gromov-Witten invariants counting rational curves in a family of orbifold blowups of the weighted projective plane ... More
Joyce-Song wall-crossing as an asymptotic expansionDec 09 2011Jun 17 2013We conjecture that the Joyce-Song wall-crossing formula for Donaldson-Thomas invariants arises naturally from an asymptotic expansion in the field theoretic work of Gaiotto, Moore and Neitzke. This would also give a new perspective on how the formulae ... More
Stable pairs, flat connections and Gopakumar-Vafa invariantsDec 04 2017Using the interpretation of certain generalised Donaldson-Thomas invariants, including stable pairs curve counts, as the monodromy of a flat connection on a formal principal bundle, we show that the conjectural Gopakumar-Vafa contributions of all genera ... More
Holder regularity and chaotic attractorsApr 06 2001Apr 13 2001We demonstrate how the Holder regularity of a given signal is a lower bound for the Grassberger-Procaccia correlation dimension of strange attractors.
A Multi-agent Based Digital Preservation ModelAug 26 2014Aug 28 2014Master's Degree Thesis: Department of Physics, University of Turin Supervisor: Prof. Marco Maggiora, Department of Physics, University of Turin; email: marco.maggiora@unito.it Co-Supervisor: Prof. Walter Allasia, Innovation Department, EURIX; email: allasia@eurix.it ... More
The thermal dilepton rate at NLO at small and large invariant massOct 02 2015Oct 05 2015We report on a recent next-to-leading order perturbative determination of the dilepton rate from a hot QCD plasma for frequency and momentum of the order of the temperature and for much smaller invariant mass $M\sim gT$. We briefly review the calculation, ... More
Theoretical aspects of photon production in high energy nuclear collisionsJul 31 2014A brief overview of the calculation of photon and dilepton production rates in a deconfined quark-gluon plasma is presented. We review leading order rates as well as recent NLO determinations and non-equilibrium corrections. Furthermore, the difficulties ... More
Heavy quarkonium spectrum and width in a weakly-coupled quark-gluon plasmaAug 30 2011Sep 20 2011We report a recent calculation of the heavy quarkonium energy levels and decay widths in a quark- gluon plasma whose temperature is much smaller than the inverse radius of the bound state, based on a Non-Relativistic Effective Field theory framework for ... More
The Polyakov loop correlator at NNLO and singlet and octet correlatorsOct 19 2010We present the complete next-to-next-to-leading-order calculation of the correlation function of two Polyakov loops for temperatures smaller than the inverse distance between the loops and larger than the Coulomb potential. We discuss the relationship ... More
Effective Field Theories of QCD for Heavy Quarkonia at Finite TemperatureJan 13 2012Quarkonium suppression is one of the most investigated probes of the medium produced in heavy-ion collisions. In this thesis we extend the well-established and successful zero temperature framework of Non-Relativistic (NR) Effective Field Theories (EFTs) ... More
Localization properties of one-dimensional speckle potentials in a boxDec 10 2012Mar 18 2014We investigate the localization properties of the single particle spectrum of a one-dimensional speckle potential in a box. We consider both the repulsive and the attractive cases. The system is controlled by two parameters: the size of the box and a ... More
W-types in setoidsSep 07 2018W-types and their categorical analogue, initial algebras for polynomial endofunctors, are an important tool in predicative systems to replace transfinite recursion on well-orderings. Current arguments to obtain W-types in quotient completions rely on ... More
Simple linear compactifications of odd orthogonal groupsMar 10 2011Nov 19 2012We classify the simple linear compactifications of SO(2r+1), namely those compactifications with a unique closed orbit which are obtained by taking the closure of the SO(2r+1)xSO(2r+1)-orbit of the identity in a projective space P(End(V)), where V is ... More
The relationship between gas content and star formation rate in spiral galaxies. Comparing the local field with the Virgo clusterAug 01 2008Oct 02 2008Despite many studies of the star formation in spiral galaxies, a complete and coherent understanding of the physical processes that regulate the birth of stars has not yet been achieved, nor a unanimous consent was reached, despite the many attempts, ... More
A double-layer reduced model for fault flow on slipping domains with hybrid finite volume schemeSep 18 2017In this work we are interested in dealing with single-phase flows in fractured porous media for underground processes. We focus our attention on domains where the presence of faults, with thickness several orders of magnitude smaller than other characteristic ... More
A category-theoretic version of the identity type weak factorization systemNov 29 2014Gambino and Garner proved that the syntactic category of a dependent type theory with identity types can be endowed with a weak factorization system structure, called identity type weak factorization system. In this paper we consider an enrichment of ... More
Energy loss at NLO in a high-temperature Quark-Gluon PlasmaJan 25 2016We present an extension of the Arnold-Moore-Yaffe kinetic equations for jet energy loss to NLO in the strong coupling constant. A novel aspect of the NLO analysis is a consistent description of wider-angle bremsstrahlung (semi-collinear emissions), which ... More
Next-to-leading order thermal photon production in a weakly-coupled plasmaApr 02 2014We summarize the recent determination to next-to-leading order of the thermal photon rate at weak coupling. We emphasize how it can be expressed in terms of gauge-invariant condensates on the light cone, which are amenable to novel sum rules and Euclidean ... More
A brief review of the theory of charmonium suppression in heavy ion collisionsNov 28 2013A brief overview of the theory of charmonium suppression in heavy ion collisions is presented. In particular I will concentrate on the effects caused by the hot, deconfined medium and on the effort to treat them using field-theoretical, QCD-based techniques, ... More
A thermodynamical approach to dissipation range turbulenceApr 08 2003A model to explain the statistics of the velocity gradients in the dissipation range of a turbulent flow is presented. The experimentally observed non-gaussian statistics is theoretically predicted by means of a thermodynamical analogy using the maximum ... More
The search for magnetic-induced charged currents in Pb--Pb collisions with ALICESep 17 2017In non-central heavy-ion collisions unprecedented strong magnetic fields, of the order of 10$^{18}$ Gauss, are expected to be produced. The interplay of such fields with QCD anomalies in the Quark--Gluon Plasma (QGP) has been predicted to lead to a number ... More
Learning Numeracy: Binary Arithmetic with Neural Turing MachinesApr 04 2019One of the main problems encountered so far with recurrent neural networks is that they struggle to retain long-time information dependencies in their recurrent connections. Neural Turing Machines (NTMs) attempt to mitigate this issue by providing the ... More
Krylov Iterative Methods for the Geometric Mean of Two Matrices Times a VectorMar 04 2019Apr 03 2019In this work, we are presenting an efficient way to compute the geometric mean of two positive definite matrices times a vector. For this purpose, we are inspecting the application of methods based on Krylov spaces to compute the square root of a matrix. ... More
New examples of non-commutative Valdivia compact spacesMar 16 2017Mar 06 2018The aim of this note is to characterize trees, endowed with coarse wedge topology, that have a retractional skeleton. We use this characterization to provide new examples of non-commutative Valdivia compact spaces that are not Valdivia.
Remarks on some simple $C^*$-algebras admitting a unique lower semicontinuous $2$-quasitraceJun 21 2018Using the different descriptions of the Cuntz semigroup, we derive some properties of simple, $\sigma$-unital $C^*$-algebras with almost unperforated Cuntz semigroup, a unique lower semicontinuous $2$-quasitrace and for which the stabilization has almost ... More
A multi-layer reduced model for flow in porous media with a fault and surrounding damage zonesMar 04 2019In this work we present a new conceptual model to describe fluid flow in a porous media system in presence of a large fault. Geological faults are often modeled simply as interfaces in the rock matrix, but they are complex structure where the high strain ... More
Truncated Quillen coplexes of p-groupsJan 29 2014Let p be an odd prime and let P be a p-group. We examine the order complex of the poset of elementary abelian subgroups of P having order at least p^2. S. Bouc and J. Th\'evenaz showed that this complex has the homotopy type of a wedge of spheres. We ... More
Hyper non-Gaussianities in inflation with strongly non-geodesic motionFeb 08 2019Several recent proposals to embed inflation into high-energy physics rely on inflationary dynamics characterized by a strongly non-geodesic motion in negatively curved field space. This naturally leads to a transient instability of perturbations on sub-Hubble ... More
The asymptotic smile of a multiscaling stochastic volatility modelJan 14 2015Oct 05 2016We consider a stochastic volatility model which captures relevant stylized facts of financial series, including the multi-scaling of moments. The volatility evolves according to a generalized Ornstein-Uhlenbeck processes with super-linear mean reversion. ... More
Symmetry breaking for Schrödinger-Poisson-Slater energyJan 21 2016We study the asymptotic behavior of ground state energy for Schr\"odinger-Poisson-Slater energy functional. We show that ground state energy restricted to radially symmetric functions is above the ground state energy when the number of particles is sufficiently ... More
On the theory of quantum quenches in near-critical systemsAug 26 2016Sep 21 2016The theory of quantum quenches in near-critical one-dimensional systems formulated in [J. Phys. A 47 (2014) 402001] yields analytic predictions for the dynamics, unveils a qualitative difference between non-interacting and interacting systems, with undamped ... More
Frobenius type and CV-structures for Donaldson-Thomas theory and a convergence propertyDec 03 2015We rephrase some well-known results in Donaldson-Thomas theory in terms of (formal families of) Frobenius type and CV-structures on a vector bundle in the sense of Hertling. We study these structures in an abstract setting, and prove a convergence result ... More
Analysis of association football playing styles: an innovative method to cluster networksMay 28 2018Jan 20 2019In this work we develop an innovative hierarchical clustering method to divide a sample of undirected weighted networks into groups. The methodology consists of two phases: the first phase is aimed at putting the single networks in a broader framework ... More
Scalar curvature and an infinite-dimensional hyperkähler reductionNov 05 2018We discuss a natural extension of the K\"ahler reduction of Fujiki and Donaldson, which realises the scalar curvature of K\"ahler metrics as a moment map, to a hyperk\"ahler reduction. Our approach is based on an explicit construction of hyperk\"ahler ... More
DepecheMood: a Lexicon for Emotion Analysis from Crowd-Annotated NewsMay 07 2014While many lexica annotated with words polarity are available for sentiment analysis, very few tackle the harder task of emotion analysis and are usually quite limited in coverage. In this paper, we present a novel approach for extracting - in a totally ... More
Crossing probability and number of crossing clusters in off-critical percolationOct 28 2011Dec 19 2011We consider two-dimensional percolation in the scaling limit close to criticality and use integrable field theory to obtain universal predictions for the probability that at least one cluster crosses between opposite sides of a rectangle of sides much ... More
Universal properties of Ising clusters and droplets near criticalityJun 11 2010Clusters and droplets of positive spins in the two-dimensional Ising model percolate at the Curie temperature in absence of external field. The percolative exponents coincide with the magnetic ones for droplets but not for clusters. We use integrable ... More
On dipolar quantum gases in the unstable regimeOct 17 2014Mar 25 2016We study the nonlinear Schr\"odinger equation arising in dipolar Bose-Einstein condensate in the unstable regime. Two cases are studied: the first when the system is free, the second when gradually a trapping potential is added. In both cases we first ... More
On translation invariant constrained minimization problems with application to Schrödinger-Poisson equationJul 23 2010Nov 19 2010In this paper we study the existence of minimizers for a class of constrained minimization problems that are invariant under translations. We call $$I_{\rho^{2}}:=\inf_{B_{\rho}}I(u) \ $$ where $B_{\rho}=\{u\in H^{m}(\R^{N}):\|u\|_{2}=\rho\},$ and $I(u)=1/2\|u\|^{2}_{D^{m,2}}+T(u)$, ... More
Towards hybrid price discrimination via neighbours properties in network-driven economyMar 27 2019Increased data gathering capacity, together with the spreading of data analytics techniques, has allowed an unprecedented concentration of information related to the individuals' preferences in the hands of a few gatekeepers. In such context, the traditional ... More
Exact completion and constructive theories of setsOct 29 2017In the present paper we use the theory of exact completions to study categorical properties of small setoids in Martin-L\"of type theory and, more generally, of models of the Constructive Elementary Theory of the Category of Sets, in terms of properties ... More
Square permutations are typically rectangularApr 05 2019We describe the limit (for two topologies) of large uniform random square permutations, i.e., permutations where every point is a record. First we describe the global behavior by showing these permutations have a permuton limit which can be described ... More
Regular functions on spherical nilpotent orbits in complex symmetric pairs: classical Hermitian casesDec 05 2016Oct 31 2017Given a classical semisimple complex algebraic group G and a symmetric pair (G,K) of Hermitian type, we study the closures of the spherical nilpotent K-orbits in the isotropy representation of K. We show that all such orbit closures are normal and describe ... More
First-Principles Determination of Electron-Ion Couplings in the Warm Dense Matter RegimeApr 09 2019We present first-principles calculations of the rate of energy exchanges between electrons and ions in nonequilibrium warm dense plasmas, liquid metals and hot solids, a fundamental property for which various models offer diverging predictions. To this ... More
Sequential motif profile of natural visibility graphsMay 09 2016The concept of sequential visibility graph motifs -subgraphs appearing with characteristic frequencies in the visibility graphs associated to time series- has been advanced recently along with a theoretical framework to compute analytically the motif ... More
Max-Min characterization of the mountain pass energy level for a class of variational problemsSep 01 2009We provide a max-min characterization of the mountain pass energy level for a family of variational problems. As a consequence we deduce the mountain pass structure of solutions to suitable PDEs, whose existence follows from classical minimization argument. ... More
Local logarithmic correlators as limits of Coulomb gas integralsNov 08 2013We will describe how logarithmic singularities arise as limits of Coulomb Gas integrals. Our approach will combine analytic properties of the time-like Liouville structure constants, together with the recursive formula of the Virasoro conformal blocks. ... More
Comparison between different methods of estimating of the relaxation times in the FPU modelApr 29 2015After a brief review of the Fermi-Pasta-Ulam (FPU) conservative system of N nonlinearly coupled oscillators, this paper addresses two problems: first, comparing two indicators for the equipartition, showing that the results are essentially identical; ... More
Braid group actions on coideal subalgebras of quantized enveloping algebrasFeb 21 2011We construct braid group actions on coideal subalgebras of quantized enveloping algebras which appear in the theory of quantum symmetric pairs. In particular, we construct an action of the semidirect product of Z^n and the classical braid group in n strands ... More
Relative K-stability of extremal metricsDec 21 2009We show that if a polarised manifold admits an extremal metric then it is K-polystable relative to a maximal torus of automorphisms.
Backtesting Lambda Value at RiskFeb 24 2016Jun 02 2017A new risk measure, the lambda value at risk (Lambda VaR), has been recently proposed from a theoretical point of view as a generalization of the value at risk (VaR). The Lambda VaR appears attractive for its potential ability to solve several problems ... More
On bisequentiality and spaces of strictly decreasing functions on treesSep 05 2018We present a characterization of spaces of strictly decreasing functions on trees in terms of bisequentiality. This characterization answers Questions 6.1 and 6.2 of "A filter on a collection of finite sets and Eberlein compacta" by T. Cie\'sla. Moreover ... More
Phase separation and interface structure in two dimensions from field theoryJun 21 2012Oct 30 2012We study phase separation in two dimensions in the scaling limit below criticality. The general form of the magnetization profile as the volume goes to infinity is determined exactly within the field theoretical framework which explicitly takes into account ... More
Potts q-color field theory and scaling random cluster modelApr 21 2011Jul 01 2011We study structural properties of the q-color Potts field theory which, for real values of q, describes the scaling limit of the random cluster model. We show that the number of independent n-point Potts spin correlators coincides with that of independent ... More
On three-point connectivity in two-dimensional percolationSep 07 2010We argue the exact universal result for the three-point connectivity of critical percolation in two dimensions. Predictions for Potts clusters and for the scaling limit below p_c are also given.
Stable standing waves for a class of nonlinear Schroedinger-Poisson equationsFeb 09 2010Mar 25 2010We prove the existence of orbitally stable standing waves with prescribed $L^2$-norm for the following Schr\"odinger-Poisson type equation \label{intro} %{%{ll} i\psi_{t}+ \Delta \psi - (|x|^{-1}*|\psi|^{2}) \psi+|\psi|^{p-2}\psi=0 \text{in} \R^{3}, %-\Delta\phi= ... More
Wavelet Cross-Correlation Analysis of Turbulent Mixing from Large-Eddy-SimulationsMar 14 2000The complex interactions existing between turbulence and mixing in a bluff-body stabilised flame configuration is investigated by means of a wavelet cross-correlation analysis on Large Eddy Simulations. The combined approach allows to better point out ... More
Torus equivariant K-stabilityFeb 10 2016We prove (using algebro-geometric methods) two results that allow to test the positivity of the Donaldson-Futaki weights of arbitrary polarised varieties via test-configurations which are equivariant with respect to a maximal torus in the automorphism ... More
Equilibrium and nonequilibrium entanglement properties of 2D and 3D Fermi gasesJan 16 2013Mar 01 2013We investigate the entanglement properties of the equilibrium and nonequilibrium quantum dynamics of 2D and 3D Fermi gases, by computing entanglement entropies of extended space regions, which generally show multiplicative logarithmic corrections to the ... More
Regular functions on spherical nilpotent orbits in complex symmetric pairs: classical Hermitian casesDec 05 2016Given a classical semisimple complex algebraic group G and a symmetric pair (G,K) of Hermitian type, we study the closures of the spherical nilpotent K-orbits in the isotropy representation of K. We show that all such orbit closures are normal and describe ... More
Il fisico del neutrinoOct 29 2013Nov 11 2014In memory of the famous physicist Bruno Pontecorvo, whereof is just occurred the centenary anniversary of the birth and the twentieth anniversary of the death, this paper traces the scientific and human adventure of the italian scientist, from the pioneering ... More
Modelling and interpreting spectral energy distributions of galaxies with BEAGLEMar 09 2016Oct 05 2016We present a new-generation tool to model and interpret spectral energy distributions (SEDs) of galaxies, which incorporates in a consistent way the production of radiation and its transfer through the interstellar and intergalactic media. This flexible ... More
The Bruhat order on Hermitian symmetric varieties and on abelian nilradicalsAug 18 2017Jul 12 2018Let $G$ be a simple algebraic group and $P$ a parabolic subgroup of $G$ with abelian unipotent radical $P^u$, and let $B$ be a Borel subgroup of $G$ contained in P. Let $\mathfrak{p}^u$ be the Lie algebra of $P^u$ and let $L$ be a Levi factor of $P$, ... More
Regular functions on spherical nilpotent orbits in complex symmetric pairs: exceptional casesOct 31 2017Given an exceptional simple complex algebraic group G and a symmetric pair (G, K), we study the spherical nilpotent K-orbit closures in the isotropy representation of K. We show that they are all normal except in one case in type G2, and compute the K-module ... More
Extracting Information from Multiplex NetworksFeb 28 2016May 16 2016Multiplex networks are generalized network structures that are able to describe networks in which the same set of nodes are connected by links that have different connotations. Multiplex networks are ubiquitous since they describe social, financial, engineering ... More
Non-stationary Magnetic Microstructures in Stellar Thin Accretion DiscsSep 24 2012Feb 27 2013We examine the morphology of magnetic structures in thin plasma accretion discs, generalizing a stationary ideal MHD model to the time-dependent visco-resistive case. Our analysis deals with small scale perturbations to a central dipole-like magnetic ... More
Sequential visibility-graph motifsDec 01 2015May 02 2016Visibility algorithms transform time series into graphs and encode dynamical information in their topology, paving the way for graph-theoretical time series analysis as well as building a bridge between nonlinear dynamics and network science. In this ... More
Efficient functional ANOVA through wavelet-domain Markov grovesFeb 12 2016Feb 21 2016We introduce a wavelet-domain functional analysis of variance (fANOVA) method based on a Bayesian hierarchical model. The factor effects are modeled through a spike-and-slab mixture at each location-scale combination along with a normal-inverse-Gamma ... More
Critical Exponents of the Random Field Hierarchical ModelSep 28 2013We have studied the one dimensional Dyson hierarchical model in presence of a random field. This is a long range model where the interactions scale with the distance with a power law-like form J(r) ~ r^{-\rho} and we can explore mean field and non-mean ... More
Orbits of strongly solvable spherical subgroups on the flag varietyNov 21 2014Apr 07 2016Let G be a connected reductive complex algebraic group and B a Borel subgroup of G. We consider a subgroup H of B acting with finitely many orbits on the flag variety G/B, and we classify the H-orbits in G/B in terms of suitable combinatorial invariants. ... More
Nonlinear Schrödinger equations with strongly singular potentialsMar 19 2009In this paper we look for standing waves for nonlinear Schr\"odinger equations $$ i\frac{\partial \psi}{\partial t}+\Delta \psi - g(|y|) \psi -W^{\prime}(| \psi |)\frac{\psi}{| \psi |}=0 $$ with cylindrically symmetric potentials $g$ vanishing at infinity ... More
A generalized Gross-Pitaevskii model for intersubband polariton lasingMar 25 2019We develop a generalized Gross-Pitaevskii approach to the driven-dissipative dynamics of intersubband polaritons in patterned planar microcavities where the cavity mode is strongly coupled to an intersubband transition in doped quantum wells. Substantial ... More
Stability and instability results in a model of Fermi accelerationMar 07 2008We consider the static wall approximation to the dynamics of a particle bouncing on a periodically oscillating infinitely heavy plate while subject to a potential force. We assume the case of a potential given by a power of the particle's height and sinusoidal ... More
The asymptotic smile of a multiscaling stochastic volatility modelJan 14 2015Jul 06 2017We consider a stochastic volatility model which captures relevant stylized facts of financial series, including the multi-scaling of moments. The volatility evolves according to a generalized Ornstein-Uhlenbeck processes with super-linear mean reversion. ... More
Normality and smoothness of simple linear group compactificationsMar 07 2012Nov 19 2012If G is a complex semisimple algebraic group, we characterize the normality and the smoothness of its simple linear compactifications, namely those equivariant GxG-compactifications which possess a unique closed orbit and which arise in a projective space ... More
Orbits of strongly solvable spherical subgroups on the flag varietyNov 21 2014Aug 02 2017Let G be a connected reductive complex algebraic group and B a Borel subgroup of G. We consider a subgroup H of B acting with finitely many orbits on the flag variety G/B, and we classify the H-orbits in G/B in terms of suitable combinatorial invariants. ... More
Some structural results on the non-abelian tensor square of groupsOct 25 2008We study the non-abelian tensor square $G\otimes G$ for the class of groups G that are finitely generated modulo their derived subgroup. In particular, we find conditions on G/G' so that $G\otimes G$ is isomorphic to the direct product of $\nabla(G)$ ... More
The complete census of optically selected AGNs in the Coma Supercluster: the dependence of AGN activity on the local environmentJul 19 2011Sep 14 2011To investigate the dependence of the occurrence of active galactic nuclei (AGNs) on local galaxy density, we study the nuclear properties of ~5000 galaxies in the Coma Supercluster whose density spans 2 orders of magnitude from the sparse filaments to ... More
PCR-based isolation of multigene families: Lessons from the avian MHC class IIBAug 01 2013The amount of sequence data available today highly facilitates the access to genes from many gene families. Universal primers amplifying the desired genes over a range of species are readily obtained by aligning conserved gene regions, and laborious gene ... More
A reduction theorem for nonsolvable finite groupsMay 15 2018Every finite group $G$ has a normal series each of whose factors is either a solvable group or a direct product of nonabelian simple groups. The minimum number of nonsolvable factors attained on all possible such series is called the nonsolvable length ... More