Results for "V. Prat"

total 76927took 0.13s
Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal componentsMar 13 2019Context. Stellar magnetic fields are one of the candidates often invoked to explain the missing transport of angular momentum observed in the models of stellar interiors. However, the properties of an internal magnetic field and the consequences of its ... More
Non-existence of reflectionless measures for the s-Riesz transform when 0<s<1Feb 05 2015Apr 15 2015A measure $\mu$ on $\mathbb{R}^d$ is called reflectionless for the $s$-Riesz transform if the singular integral $R^s\mu(x)=\int \frac{y-x}{|y-x|^{s+1}}\,d\mu(y)$ is constant on the support of $\mu$ in some weak sense and, moreover, the operator defined ... More
Global smoothness of quasiconformal mappings in the Triebel-Lizorkin scaleJan 23 2019We give sufficient conditions for quasiconformal mappings between simply connected Lipschitz domains to have H\"older, Sobolev and Triebel-Lizorkin regularity in terms of the regularity of the boundary of the domains and the regularity of the Beltrami ... More
Understanding Graph Structure of Wikipedia for Query ExpansionMay 06 2015Knowledge bases are very good sources for knowledge extraction, the ability to create knowledge from structured and unstructured sources and use it to improve automatic processes as query expansion. However, extracting knowledge from unstructured sources ... More
Sobolev regularity of the Beurling transform on planar domainsJul 15 2015Jun 21 2017Consider a Lipschitz domain $\Omega$ and the Beurling transform of its characteristic function $\mathcal{B} \chi_\Omega(z)= - {\rm p.v.}\frac1{\pi z^2}*\chi_\Omega (z) $. It is shown that if the outward unit normal vector $N$ of the boundary of the domain ... More
Sobolev regularity of the Beurling transform on planar domainsJul 15 2015May 11 2016Consider a Lipschitz domain $\Omega$ and the Beurling transform of its characteristic function $\mathcal{B} \chi_\Omega(z)= - {\rm p.v.}\frac1{\pi z^2}*\chi_\Omega (z) $. It is shown that if the outward unit normal vector $N$ of the boundary of the domain ... More
Measuring Triebel-Lizorkin fractional smoothness on domains in terms of first-order differencesApr 16 2018Oct 02 2018In this note we give equivalent characterizations for a fractional Triebel-Lizorkin space $F^s_{p,q}(\Omega)$ in terms of first-order differences in a uniform domain $\Omega$. The characterization is valid for any positive, non-integer real smoothness ... More
Sobolev regularity of quasiconformal mappings on domainsJul 15 2015Sep 07 2015Consider a Lipschitz domain $\Omega$ and a measurable function $\mu$ supported in $\overline\Omega$ with $\left\|{\mu}\right\|_{L^\infty}<1$. Then the derivatives of a quasiconformal solution of the Beltrami equation $\overline{\partial} f =\mu \partial ... More
On the semiadditivity of the capacities associated with signed vector valued Riesz kernelsJul 13 2010The aim of this paper is to show the semiadditivity of the capacities associated to the signed vector valued Riesz kernels of homogeneity $-\alpha$ in $\mathbb{R}^n$, with $0<\alpha<n$.
Beltrami equations in the plane and Sobolev regularityJun 24 2016Jul 28 2016Some new results regarding the Sobolev regularity of the principal solution of the linear Beltrami equation $\bar{\partial} f = \mu \partial f + \nu \bar{\partial f}$ for discontinuous Beltrami coefficients $\mu$ and $\nu$ are obtained, using Kato-Ponce ... More
A model of loops in 2-DAug 25 2003Aug 26 2003The gonihedric spin model was first introduced as the action for a discretized tensionless string in a discretized embeding space. Afterwards was found that there are interesting features on the dynamical behavior of this model in 3 dimensions (as it ... More
Fine-structure constant constraints on late-time dark energy transitionsMar 08 2019We use recent astrophysical and local tests of the stability of the fine-structure constant, $\alpha$, to constrain a particular phenomenological but physically motivated class of models in which the dark energy equation of state can undergo a rapid transition ... More
Beltrami equations in the plane and Sobolev regularityJun 24 2016Jan 31 2017New results regarding the Sobolev regularity of the principal solution of the linear Beltrami equation $\bar{\partial} f = \mu \partial f + \nu \overline{\partial f}$ for discontinuous Beltrami coefficients $\mu$ and $\nu$ are obtained, using Kato-Ponce ... More
Sobolev regularity of quasiconformal mappings on domainsJul 15 2015Dec 16 2016Consider a Lipschitz domain $\Omega$ and a measurable function $\mu$ supported in $\overline\Omega$ with $\left\|{\mu}\right\|_{L^\infty}<1$. Then the derivatives of a quasiconformal solution of the Beltrami equation $\overline{\partial} f =\mu \partial ... More
2D computations of g modesSep 30 2011Nov 16 2011We present complete 2D computations of g modes in distorted polytropic models of stars performed with the Two-dimensional Oscillation Program (TOP). We computed low-degree modes (l=1 modes with radial order n=-1...-14, and l=2,3 modes with n=-1...-5 and ... More
Mode visibilities in rapidly rotating starsDec 11 2012Context: Mode identification is a crucial step to comparing observed frequencies with theoretical ones, but has proven to be difficult in rapidly rotating stars. Aims: To further constrain mode identification, we aim to accurately calculate mode visibilities ... More
Quasi full-disk maps of solar horizontal velocities using SDO/HMI dataMar 02 2012For the first time, the motion of granules (solar plasma on the surface on scales larger than 2.5 Mm) has been followed over the entire visible surface of the Sun, using SDO/HMI white-light data. Horizontal velocity fields are derived from image correlation ... More
Turbulent transport in radiative zones of starsJan 17 2013Jan 22 2013Context. In stellar interiors, rotation is able to drive turbulent motions, and the related transport processes have a significant influence on the evolution of stars. Turbulent mixing in the radiative zones is currently taken into account in stellar ... More
Sharp bounds for composition with quasiconformal mappings in Sobolev spacesDec 02 2016Let $\phi$ be a quasiconformal mapping, and let $T_\phi$ be the composition operator which maps $f$ to $f\circ\phi$. Since $\phi$ may not be bi-Lipschitz, the composition operator might not map Sobolev spaces to themselves. The study begins with the behavior ... More
On gonihedric loops and quantum gravityNov 04 2005We present an analysis of the gonihedric loop model, a reformulation of the two dimensional gonihedric spin model, using two different techniques. First, the usual regular lattice statistical physics problem is mapped onto a height model and studied analytically. ... More
Towards a property graph generator for benchmarkingApr 03 2017The use of synthetic graph generators is a common practice among graph-oriented benchmark designers, as it allows obtaining graphs with the required scale and characteristics. However, finding a graph generator that accurately fits the needs of a given ... More
Sharp bounds for composition with quasiconformal mappings in Sobolev spacesDec 02 2016Dec 16 2016Let $\phi$ be a quasiconformal mapping, and let $T_\phi$ be the composition operator which maps $f$ to $f\circ\phi$. Since $\phi$ may not be bi-Lipschitz, the composition operator need not map Sobolev spaces to themselves. The study begins with the behavior ... More
Some Calderón-Zygmund kernels and their relations to Wolff capacities and rectifiabilityJan 27 2014We consider the Calder\'on-Zygmund kernels $K_ {\alpha,n}(x)=(x_i^{2n-1}/|x|^{2n-1+\alpha})_{i=1}^d$ in $\mathbb{R}^n$ for $0<\alpha\leq 1$ and $n\in\mathbb{N}$. We show that, on the plane, for $0<\alpha<1$, the capacity associated to the kernels $K_{\alpha,n}$ ... More
Shear mixing in stellar radiative zones I. Effect of thermal diffusion and chemical stratificationApr 24 2014May 15 2014Turbulent transport of chemical elements in radiative zones of stars is considered in current stellar evolution codes thanks to phenomenologically derived diffusion coefficients. Recent local numerical simulations (Prat & Ligni\`eres 2013, A&A, 551, L3) ... More
A T(P) theorem for Sobolev spaces on domainsJun 18 2014Jan 22 2015Recently, V. Cruz, J. Mateu and J. Orobitg have proved a T(1) theorem for the Beurling transform in the complex plane. It asserts that given $0<s\leq1$, $1<p<\infty$ with $sp>2$ and a Lipschitz domain $\Omega\subset \mathbb{C}$, the Beurling transform ... More
Dynamics of the two-dimensional gonihedric spin modelDec 30 2003Nov 15 2005In this paper we study dynamical aspects of the two-dimensional gonihedric spin model using both numerical and analytical methods. This spin model has vanishing microscopic surface tension and it actually describes an ensemble of loops living on a 2D ... More
Exploiting the Accumulated Evidence for Gene Selection in Microarray Gene Expression DataMar 01 2013Machine Learning methods have of late made significant efforts to solving multidisciplinary problems in the field of cancer classification using microarray gene expression data. Feature subset selection methods can play an important role in the modeling ... More
Asymptotics for the heat kernel in multicone domainsJan 19 2015Jan 23 2015A multi cone domain $\Omega \subseteq \mathbb{R}^n$ is an open, connected set that resembles a finite collection of cones far away from the origin. We study the rate of decay in time of the heat kernel $p(t,x,y)$ of a Brownian motion killed upon exiting ... More
A T(1) theorem for fractional Sobolev spaces on domainsJul 14 2015Jun 27 2016Given any uniform domain $\Omega$, the Triebel-Lizorkin space $F^s_{p,q}(\Omega)$ with $0<s<1$ and $1<p,q<\infty$ can be equipped with a norm in terms of first order differences restricted to pairs of points whose distance is comparable to their distance ... More
Ejection of the corona at State transitions: a common behaviour in microquasars?Feb 09 2009The onset of most microquasar outbursts is characterized by a state transition between a Low/Hard State (LHS) and a High/Soft State (HSS). Besides drastic spectral and timing changes, this transition often shows a discrete ejection event detectable in ... More
Is the ejection of the corona a general phenomenon in microquasars?Nov 21 2008We study the evolution of some microquasars during their outbursts as observed with the X-ray telescopes RXTE and INTEGRAL. We focus on the interplay between the accretion disc, and the medium responsible for the production of the hard X-rays (the so-called ... More
New recursive residue formulas for the topological expansion of the Cauchy Matrix ModelDec 15 2009Sep 14 2010In a recent work [1] we consider the topological expansion for the non-mixed observables (including the free energy) for the formal Cauchy matrix model. The only restriction in [1] was the fact that all the branch points have to be simple. This excludes ... More
Characterization for stability in planar conductivitiesJan 23 2017Mar 31 2017We find a complete characterization for sets of isotropic conductivities with stable recovery in the $L^2$ norm when the data of the Calder\'on Inverse Conductivity Problem is obtained in the boundary of a disk and the conductivities are constant in a ... More
Topological expansion of the chain of matricesMay 09 2008Jun 20 2009We solve the loop equations to all orders in $1/N^2$, for the Chain of Matrices matrix model (with possibly an external field coupled to the last matrix of the chain). We show that the topological expansion of the free energy, is, like for the 1 and 2-matrix ... More
Topological Expansion for the Cauchy two-Matrix-ModelMar 13 2009Recently, a two-matrix-model with a new type of interaction [1] has been introduced and analyzed using bi-orthogonal polynomial techniques. Here we present the complete 1/N^2 expansion for the formal version of this model, following the spirit of [2,3], ... More
2-matrix versus complex matrix model, integrals over the unitary group as triangular integralsFeb 03 2005We prove that the 2-hermitean matrix model and the complex-matrix model obey the same loop equations, and as a byproduct, we find a formula for Itzykzon-Zuber's type integrals over the unitary group. Integrals over U(n) are rewritten as gaussian integrals ... More
Comparison of solar horizontal velocity fields from SDO/HMI and Hinode dataMar 18 2013The measurement of the Sun's surface motions with a high spatial and temporal resolution is still a challenge. We wish to validate horizontal velocity measurements all over the visible disk of the Sun from Solar Dynamics Observatory/ Helioseismic and ... More
Harish-Chandra integrals as nilpotent integralsJan 22 2008Recently the correlation functions of the so-called Itzykson-Zuber/Harish-Chandra integrals were computed (by one of the authors and collaborators) for all classical groups using an integration formula that relates integrals over compact groups with respect ... More
True amplitude one-way propagation in heterogeneous mediaApr 21 2008This paper deals with the numerical analysis of two one-way systems derived from the general complete modeling proposed by M.V. De Hoop. The main goal of this work is to compare two different formulations in which a correcting term allows to improve the ... More
Capacities associated with scalar signed Riesz kernels, and analytic capacityApr 13 2010Mar 12 2014The real and imaginari parts of the Cauchy kernel in the plane are scalar Riesz kernels of homogeneity -1. One can associate with each of them a natural notion of capacity related to bounded potentials. The main result of the paper asserts that these ... More
Toward better feature weighting algorithms: a focus on ReliefSep 12 2015Sep 16 2015Feature weighting algorithms try to solve a problem of great importance nowadays in machine learning: The search of a relevance measure for the features of a given domain. This relevance is primarily used for feature selection as feature weighting can ... More
Magnetic energy harvesting and concentration at distance by transformation opticsJul 30 2012Magnetic energy is one the main agents powering our society: generating energy in power plants, keeping information in magnetic memories, moving our devices with motors. All of these applications require a certain spatial distribution of magnetic energy, ... More
Exact cloaking of uniform magnetic fields with a superconductor-magnetic bilayerDec 13 2011The experimental realization of cloaks for electromagnetic fields has been possible only in reduced schemes because of extreme material conditions required in exact cloaks. Here we analytically demonstrate that a simple arrangement of two concentric homogeneous ... More
Asymptotic theory of gravity modes in rotating stars. I. Ray dynamicsDec 30 2015Jan 15 2016Context. The seismology of early-type stars is limited by our incomplete understanding of gravito-inertial modes. Aims. We develop a short-wavelength asymptotic analysis for gravito-inertial modes in rotating stars. Methods. The Wentzel-Kramers-Brillouin ... More
Semiclassical spectral function and density of states in speckle potentialsJun 07 2016Jul 18 2016We present a novel analytical method for calculating the spectral function and the density of states in speckle potentials, valid in the semiclassical regime. Our approach relies on stationary phase approximations, allowing us to describe the singular ... More
Long term characterization of voltage referencesDec 18 2013We report here the characterization (temperature coefficients and noise level) of selected voltage references in the frequency range from 10^(-5) to 10 Hz. The goal of this work is to update previous studies, with a characterization at lower frequencies, ... More
Double Relief with progressive weighting functionSep 12 2015Sep 16 2015Feature weighting algorithms try to solve a problem of great importance nowadays in machine learning: The search of a relevance measure for the features of a given domain. This relevance is primarily used for feature selection as feature weighting can ... More
Stringification of Chiral Dynamics: Wess-Zumino interactionDec 25 2004Jan 05 2005The QCD hadronic string is supplemented with the reparameterization-invariant boundary interaction to background chiral fields associated with pions in a way compatible with the conformal symmetry. It allows the full reconstruction of the P-even part ... More
Ion Transport and Precipitation Kinetics as Key Aspects of Stress Generation on Pore Walls Induced by Salt CrystallizationFeb 06 2018The stress generation on pore walls due to the growth of a sodium chloride crystal in a confined aqueous solution is studied from evaporation experiments in microfluidic channels in conjunction with numerical computations of crystal growth. The study ... More
The capacity associated to signed Riesz kernels, and Wolff potentialsNov 19 2004There is a natural capacity associated to any vector valued Riesz kernel of a given homogeneity. If we are in the plane and the kernel is the Cauchy kernel, then this capacity is analytic capacity. Our main result states that if the homogeneity of the ... More
Direct observation of pore collapse and tensile stress generation on pore wall due to salt crystallizationJan 03 2019The generation of stress in a pore due to salt crystallization is generally analysed as a compressive stress generation mechanism using the concept of crystallization pressure. We report on a completely different stress generation mechanism. In contrast ... More
Characterizing the radio--X-ray connection in GRS 1915+105May 18 2010We analyzed radio and X-ray observations of GRS 1915+105, between May 1995 and June 2006, focusing on the times characterized by radio flares and cycles of hard dips-soft spikes in the X-ray lightcurve. Assuming these flares to be discrete ejections, ... More
Chiral dynamics from the hadronic string: general formalismJul 21 2005Jul 22 2005QCD at long distances can be described by the chiral Lagrangian. On the other hand there is overwhelming evidence that QCD and all non-abelian theories admit an effective string description. Here we review a derivation of the (intrinsic) parity-even chiral ... More
$L^2$-boundedness of gradients of single layer potentials and uniform rectifiabilityOct 15 2018Nov 27 2018Let $A(\cdot)$ be an $(n+1)\times (n+1)$ uniformly elliptic matrix with H\"older continuous real coefficients and let $\mathcal E_A(x,y)$ be the fundamental solution of the PDE $\mathrm{div} A(\cdot) \nabla u =0$ in $\mathbb R^{n+1}$. Let $\mu$ be a compactly ... More
RXTE and INTEGRAL observations of IGR J19140+0951Jan 07 2008We have used the RXTE and INTEGRAL satellites simultaneously to observe the High Mass X-ray binary IGR J19140+0951. The spectra obtained in the 3-80 keV range have allowed us to perform a precise spectral analysis of the system along its binary orbit. ... More
Experimental realization of magnetic energy concentration and transmission at a distance by metamaterialsAug 27 2013Controlling electromagnetic energy is essential for an efficient and sustainable society. A key requirement is concentrating magnetic energy in a desired volume of space in order to either extract the energy to produce work or store it. Metamaterials ... More
Square functions of fractional homogeneity and Wolff potentialsOct 20 2014Apr 22 2015In this paper it is shown that for anymeasure $\mu$ in $\mathbb{R}^d$ and for a non-integer $0<s<d$, the Wolff energy $\displaystyle{\iint_0^\infty(\frac{\mu(B(x,r))}{r^s})^2\,\frac{dr}{r}d\mu(x)}$ is comparable to $$\iint_0^\infty(\frac{\mu(B(x,r))}{r^s} ... More
Slow dynamics in the 3--D gonihedric modelApr 18 2002We study dynamical aspects of three--dimensional gonihedric spins by using Monte--Carlo methods. The interest of this family of models (parametrized by one self-avoidance parameter $\kappa$) lies in their capability to show remarkably slow dynamics and ... More
Waves in the radiative zones of rotating, magnetized starsOct 04 2018Oct 12 2018Asteroseismology has reached a level of accuracy that may allow us to detect the effect of a deep magnetic field on oscillation modes. We thus aim to develop an asymptotic theory for short-wavelength waves in radiative zones of rotating stars with a general ... More
Shear mixing in stellar radiative zones - II. Robustness of numerical simulationsDec 14 2015Jun 07 2016Recent numerical simulations suggest that the model by Zahn (1992, A&A, 265, 115) for the turbulent mixing of chemical elements due to differential rotation in stellar radiative zones is valid. We investigate the robustness of this result with respect ... More
Capacities associated with Calderón-Zygmund kernelsDec 16 2011Aug 29 2012Analytic capacity is associated with the Cauchy kernel $1/z$ and the $L^\infty$-norm. For $n\in\mathbb{N}$, one has likewise capacities related to the kernels $K_i(x)=x_i^{2n-1}/|x|^{2n}$, $1\le i\le 2$, $x=(x_1,x_2)\in\mathbb{R}^2$. The main result of ... More
Dispersion based beam tilt correctionAug 28 2013In Free Electron Lasers (FEL), a transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch and therefore the FEL performance. The dominant sources of slice misalignments ... More
Loop equations and topological recursion for the arbitrary-$β$ two-matrix modelJun 01 2011Mar 17 2012We write the loop equations for the $\beta$ two-matrix model, and we propose a topological recursion algorithm to solve them, order by order in a small parameter. We find that to leading order, the spectral curve is a "quantum" spectral curve, i.e. it ... More
The 2m <= r property of spherically symmetric static spacetimesFeb 01 2002We prove that all spherically symmetric static spacetimes which are both regular at r=0 and satisfying the single energy condition rho + p_r + p_t >= 0 cannot contain any black hole region (equivalently, they must satisfy 2m/r <= 1 everywhere). This result ... More
Toward a consistent use of overshooting parametrizations in 1D stellar evolution codesJun 09 2015Jun 26 2015Several parametrizations for overshooting in 1D stellar evolution calculations coexist in the literature. These parametrizations are used somewhat arbitrarily in stellar evolution codes, based on what works best for a given problem, or even for historical ... More
Circumventing Magnetic Reciprocity: a Magnetic DiodeJan 30 2018Lorentz reciprocity establishes a stringent relation between electromagnetic fields and their sources. For static magnetic fields a relation between magnetic sources and fields can be drawn in analogy to the Green's reciprocity principle for electrostatics. ... More
Query Expansion via structural motifs in Wikipedia GraphFeb 23 2016May 12 2016The search for relevant information can be very frustrating for users who, unintentionally, use too general or inappropriate keywords to express their requests. To overcome this situation, query expansion techniques aim at transforming the user request ... More
Antimagnets: Controlling magnetic fields with superconductor-metamaterial hybridsJul 08 2011Magnetism is very important in science and technology, from magnetic recording to energy generation to trapping cold atoms. Physicists have managed to master magnetism - to create and manipulate magnetic fields- almost at will. Surprisingly, there is ... More
Density split statistics: Cosmological constraints from counts and lensing in cells in DES Y1 and SDSS dataOct 13 2017Jul 24 2018We derive cosmological constraints from the probability distribution function (PDF) of evolved large-scale matter density fluctuations. We do this by splitting lines of sight by density based on their count of tracer galaxies, and by measuring both gravitational ... More
Distributed Community Detection with the WCC MetricNov 03 2014Community detection has become an extremely active area of research in recent years, with researchers proposing various new metrics and algorithms to address the problem. Recently, the Weighted Community Clustering (WCC) metric was proposed as a novel ... More
Adaptive and application dependent runtime guided hardware prefetcher reconfiguration on the IBM POWER7Jan 09 2015Hardware data prefetcher engines have been extensively used to reduce the impact of memory latency. However, microprocessors' hardware prefetcher engines do not include any automatic hardware control able to dynamically tune their operation. This lacking ... More
Calderón-Zygmund kernels and rectifiability in the planeOct 06 2011Aug 29 2012Let $E \subset \C$ be a Borel set with finite length, that is, $0<\mathcal{H}^1 (E)<\infty$. By a theorem of David and L\'eger, the $L^2 (\mathcal{H}^1 \lfloor E)$-boundedness of the singular integral associated to the Cauchy kernel (or even to one of ... More
Peering through the stellar wind of IGR J19140+0951 with simultaneous INTEGRAL/RXTE observationsJun 11 2008We have used the RXTE and INTEGRAL satellites simultaneously to observe the High Mass X-ray binary IGR J19140+0951. The spectra obtained in the 3--80 keV range have allowed us to perform a precise spectral analysis of the system along its binary orbit. ... More
Commissioning experience and beam physics measurements at the SwissFEL Injector Test FacilityJun 08 2016Aug 18 2016The SwissFEL Injector Test Facility operated at the Paul Scherrer Institute between 2010 and 2014, serving as a pilot plant and testbed for the development and realization of SwissFEL, the X-ray Free-Electron Laser facility under construction at the same ... More
State space modelling and data analysis exercises in LISA PathfinderJun 19 2013Jun 21 2013LISA Pathfinder is a mission planned by the European Space Agency to test the key technologies that will allow the detection of gravitational waves in space. The instrument on-board, the LISA Technology package, will undergo an exhaustive campaign of ... More
The Splashback Feature around DES Galaxy Clusters: Galaxy Density and Weak Lensing ProfilesOct 18 2017Jul 31 2018Splashback refers to the process of matter that is accreting onto a dark matter halo reaching its first orbital apocenter and turning around in its orbit. The cluster-centric radius at which this process occurs, r_sp, defines a halo boundary that is connected ... More
Cosmological lensing ratios with DES Y1, SPT and PlanckOct 04 2018Correlations between tracers of the matter density field and gravitational lensing are sensitive to the evolution of the matter power spectrum and the expansion rate across cosmic time. Appropriately defined ratios of such correlation functions, on the ... More
Dark Energy Survey Year 1 Results: Galaxy-Galaxy LensingAug 04 2017Sep 04 2018We present galaxy-galaxy lensing measurements from 1321 sq. deg. of the Dark Energy Survey (DES) Year 1 (Y1) data. The lens sample consists of a selection of 660,000 red galaxies with high-precision photometric redshifts, known as redMaGiC, split into ... More
The Non-Linear Power Spectrum of the Lyman Alpha ForestJun 15 2015Oct 21 2015The Lyman alpha forest power spectrum has been measured on large scales by the BOSS survey in SDSS-III at $z\sim 2.3$, has been shown to agree well with linear theory predictions, and has provided the first measurement of Baryon Acoustic Oscillations ... More
Quantum Interference of a MicrosphereMar 04 2016We propose and analyze an all-magnetic scheme to perform a Young's double slit experiment with a micron-sized superconducting sphere of mass $ \gtrsim 10^{13}$ amu. We show that its center of mass could be prepared in a spatial quantum superposition state ... More
Weighted Contrastive DivergenceJan 08 2018Jul 12 2018Learning algorithms for energy based Boltzmann architectures that rely on gradient descent are in general computationally prohibitive, typically due to the exponential number of terms involved in computing the partition function. In this way one has to ... More
Shaping Communities out of TrianglesJul 26 2012Community detection has arisen as one of the most relevant topics in the field of graph data mining due to its importance in many fields such as biology, social networks or network traffic analysis. The metrics proposed to shape communities are generic ... More
Long-Distance Transfer and Routing of Static Magnetic FieldsApr 23 2013Sep 02 2014We show how the static magnetic field of a finite source can be transferred and routed to arbitrary long distances. This is achieved by using transformation optics, which results in a device made of a material with a highly anisotropic magnetic permeability. ... More
Anisotropic turbulent transport in stably stratified rotating stellar radiation zonesAug 06 2018Rotation is one of the key physical mechanisms that deeply impact the evolution of stars. Helio- and asteroseismology reveal a strong extraction of angular momentum from stellar radiation zones over the whole Hertzsprung-Russell diagram. Turbulent transport ... More
Period spacing of gravity modes strongly affected by rotation. Going beyond the traditional approximationNov 29 2016Dec 14 2016Context. As of today, asteroseismology mainly allows us to probe the internal rotation of stars when modes are only weakly affected by rotation using perturbative methods. Such methods cannot be applied to rapidly rotating stars, which exhibit complex ... More
Negative permeability in magnetostatics and its experimental demonstrationMar 21 2018The control of magnetic fields, essential for our science and technology, is currently achieved by magnetic materials with positive permeability, including ferromagnetic, paramagnetic, and diamagnetic types. Here we introduce materials with negative static ... More
Period spacing of gravity modes strongly affected by rotation. Going beyond the traditional approximationNov 29 2016Context. As of today, asteroseismology mainly allows us to probe internal rotation of stars when modes are only weakly affected by rotation using perturbative methods. Such methods cannot be applied to rapidly rotating stars, which exhibit complex oscillation ... More
Progress towards an electro-optical simulator for space based, long arms interferometersSep 04 2013We report the progress in the realization of an electronic / optical simulator for space based, long arm interferometry and its application to the eLISA mission. The goal of this work is to generate realistic optics and electronics signals, especially ... More
Large-amplitude undulatory swimming near a wallDec 09 2014The propulsive dynamics of a flexible undulating foil in a self-propelled swimming configuration near a wall is studied experimentally. Measurements of the swimming speed and the propulsive force are presented, together with image acquisition of the kinematics ... More
Correlation Functions of Harish-Chandra Integrals over the Orthogonal and the Symplectic GroupsOct 20 2006Feb 25 2008The Harish-Chandra correlation functions, i.e. integrals over compact groups of invariant monomials prod tr{X^{p_1} Omega Y^{q_1} Omega^dagger X^{p_2} ... with the weight exp tr{X Omega Y Omega^dagger} are computed for the orthogonal and symplectic groups. ... More
Impact of general differential rotation on gravity waves in rapidly rotating starsDec 07 2018Differential rotation plays a key role in stellar evolution by triggering hydrodynamical instabilities and large-scale motions that induce transport of chemicals and angular momentum and by modifying the propagation and the frequency spectrum of gravito-inertial ... More
On the relevance of bubbles and potential flows for stellar convectionJan 21 2016Recently Pasetto et al. have proposed a new method to derive a convection theory appropriate for the implementation in stellar evolution codes. Their approach is based on the simple physical picture of spherical bubbles moving within a potential flow ... More
Asymptotic theory of gravity modes in rotating stars II. Impact of general differential rotationMar 12 2018Mar 21 2018Context. Differential rotation has a strong influence on stellar internal dynamics and evolution, notably by triggering hydrodynamical instabilities, by interacting with the magnetic field, and more generally by inducing transport of angular momentum ... More
Seismic diagnosis from gravity modes strongly affected by rotationOct 27 2016Most of the information we have about the internal rotation of stars comes from modes that are weakly affected by rotation, for example by using rotational splittings. In contrast, we present here a method, based on the asymptotic theory of Prat et al. ... More
A remark on the Dixmier ConjectureNov 30 2018The Dixmier Conjecture says that every endomorphism of the (first) Weyl algebra $A_1$ (over a field of characteristic zero) is an automorphism, i.e., if $PQ-QP=1$ for some $P, Q \in A_1$ then $A_1 = K \langle P, Q \rangle$. The Weyl algebra $A_1$ is a ... More
Polaron spin echo envelope modulations in an organic semiconducting polymerSep 09 2016Theoretical treatment of the electron spin echo envelope modulation (ESEEM) spectra from polarons in a semiconducting $\pi$- conjugated polymer is presented. The contact hyperfine coupling and the dipolar interaction between the polaron and proton spins ... More
Decay of the rotary echoes for the spin of a nitrogen-vacancy center in diamondMar 25 2014We study dynamics of the electron spin of a nitrogen-vacancy (NV) center subjected to a strong driving field with periodically reversed direction (train of rotary echoes). We use analytical and numerical tools to analyze in detail the form and timescales ... More
Constructing the ultimate theory of grand unificationMay 16 2011Nov 02 2011In accordance with known phenomenological facts on leptons and quarks in the Standard Model as well as on the scale of neutrino masses and introducing the supersymmetry, we logically substantiate the unique composition of fundamental representation for ... More
Theory of the electron relaxation in metals excited by an ultrashort optical pumpAug 20 2013Mar 05 2014The theory of the electron relaxation in metals excited by an ultrashort optical pump is developed on the basis of the solution of the linearized kinetic equation. The kinetic equation includes both the electron-electron and the electron-phonon collision ... More
Double resonant processes in $χ^{(2)}$ nonlinear periodic mediaAug 07 2000In a one-dimensional periodic nonlinear $\chi^{(2)}$ medium, by choosing a proper material and geometrical parameters of the structure, it is possible to obtain two matching conditions for simultaneous generation of second and third harmonics. This leads ... More