Results for "N. Clerc"

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Towards mapping the turbulence in the intra-cluster medium -- II. Measurement uncertainties in the estimation of structure functionsApr 12 2019X-ray observations of the hot gas filling the intra-cluster medium provide a wealth of information on the dynamics of clusters of galaxies. The global equilibrium of the ICM is believed to be partially ensured by non-thermal pressure support, notably ... More
Towards mapping turbulence in the intra-cluster medium -- I. Sample variance in spatially-resolved X-ray line diagnosticsApr 12 2019X-ray observations of galaxy clusters provide insights on the nature of gaseous turbulent motions, their physical scales and on the fundamental processes they are related to. Spatially-resolved, high-resolution spectral measurements of X-ray emission ... More
The XXL Survey: XXXIII. Chandra Constraints on the AGN Contamination of z > 1 XXL Galaxy ClustersAug 14 2018Context. The XMM-XXL survey uses observations from XMM-Newton to detect clusters of galaxies over a wide range in mass and redshift. The moderate PSF of XMM-Newton means that point sources within or projected onto a cluster may not be separated from the ... More
Dielectric loss of 2D metal-insulator composite near the percolation thresholdOct 20 2007The frequency dependence of the dielectric loss angle for a metal-insulator composite was shown previously to be an efficient method to experimentally determine the percolation threshold. The statistical properties of this angle are found here to be similar ... More
The connecting solution of the Painlevé phase transition modelJul 15 2018Jan 25 2019The second Painlev\'e O.D.E. $y''-xy-2y^3=0$, $x\in \mathbb{R},$ is known to play an important role in the theory of integrable systems, random matrices, Bose-Einstein condensates and other problems. The generalized second Painlev\'e equation $\Delta ... More
A Chandra view of the z=1.62 galaxy cluster IRC-0218ASep 28 2011Jan 18 2012Context: Very few z > 1.5 clusters of galaxies are known. It is important to study the properties of galaxies in these clusters and the ICM and, further, to cross-check the reliability of the various mass estimates. This will help to clarify the process ... More
7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACISJun 13 2016Recently an unidentified emission line at 3.55 keV has been detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV sterile neutrinos, which have been proposed as a dark matter candidate. ... More
Thermodynamic perturbations in the X-ray halo of 33 clusters of galaxies observed with Chandra ACISOct 28 2015In high-resolution X-ray observations of the hot plasma in clusters of galaxies significant structures caused by AGN feedback, mergers, and turbulence can be detected. Many clusters have been observed by Chandra in great depth and at high resolution. ... More
The cosmological analysis of X-ray cluster surveys; III. Bypassing cluster mass measurementsSep 25 2016Despite strong theoretical arguments, the use of clusters as cosmological probes is, in practice, frequently questioned because of the many uncertainties impinging on cluster mass estimates. Our aim is to develop a fully self-consistent cosmological approach ... More
Precision cosmology with a wide area XMM cluster surveySep 16 2010Jul 06 2011We explore the cosmological constraints expected from wide area XMM-type cluster surveys covering 50-200 deg2, under realistic observing conditions. We perform a Fisher matrix analysis based on cluster number counts in combination with estimates of the ... More
Measuring turbulence and gas motions in galaxy clusters via synthetic Athena X-IFU observationsMay 07 2018Jul 18 2018The X-ray Integral Field Unit (X-IFU) that will be on board the Athena telescope will provide an unprecedented view of the intracluster medium (ICM) kinematics through the observation of gas velocity, $v$, and velocity dispersion, $w$, via centroid-shift ... More
Redshift-space correlation functions in large galaxy cluster surveysMay 22 2012May 16 2013Large ongoing and upcoming galaxy cluster surveys in the optical, X-ray and millimetric wavelengths will provide rich samples of galaxy clusters at unprecedented depths. One key observable for constraining cosmological models is the correlation function ... More
Symmetry breaking differential operators, the source operator and Rodrigues formulæFeb 16 2019Apr 16 2019A Rodrigues type formula is obtained for the symbols of the covariant bi-differential operators on a simple Jordan algebra.
Conformally covariant differential operators for the diagonal action of O(p, q) on real quadricsJul 17 2017Let $X=G/P$ be a real projective quadric, where $G=O(p,q)$ and $P$ is a parabolic subgroup of $G$. Let $\left(\pi_{\lambda,\epsilon}, \mathcal{H}_{\lambda,\epsilon}\right)_{ (\lambda,\epsilon)\in \mathbb {C}\times \{\pm\}}$ be the family of (smooth) representations ... More
Singular conformally invariant trilinear forms and covariant differential operators on the sphereFeb 09 2011Let $G=SO_0(1,n)$ be the conformal group acting on the $(n-1)$ dimensional sphere $S$, and let $(\pi_\lambda)_{\lambda\in \mathbb C}$ be the spherical principal series. For generic values of $\boldsymbol \lambda =(\lambda_1,\lambda_2,\lambda_3)$ in $\mathbb ... More
Wavelet analysis of baryon acoustic structures in the galaxy distributionJan 10 2011Mar 14 2012Baryon Acoustic Oscillations (BAO) are a feature imprinted in the density field by acoustic waves travelling in the plasma of the early universe. Their fixed scale can be used as a standard ruler to study the geometry of the universe. BAO have been previously ... More
Another approach to Juhl's conformally covariant differential operators from $S^n$ to $S^{n-1}$Dec 06 2016A new construction of Juhl's conformally covariant differential operators from $S^n$ to $S^{n-1}$ (or from $\mathbb R^n$ to $\mathbb R^{n-1}$) is proposed. They are obtained as the composition of a new family of differential operators on $S^n$, covariant ... More
Singular conformally invariant trilinear forms, I Multiplicity one resultsNov 13 2014Feb 24 2015A normalized holomorphic family (depending on $\boldsymbol \lambda \in \mathbb C^3$) of conformally invariant trilinear forms on the sphere is studied. Its zero set $Z$ is described. For $\boldsymbol \lambda\notin Z$, the multiplicity of the space of ... More
Intertwining operators for the generalized principal series on symmetric R-spacesSep 04 2012Three questions about the intertwining operators for the generalized principal series on a symmetric R-space are solved : description of the functional kernel, both in the compact and the non-compact picture, domain of convergence, meromorphic continuation. ... More
X-ray AGN in the XMM-LSS galaxy clusters: no evidence of AGN suppressionFeb 17 2014May 28 2014We present a study of the overdensity of X-ray selected AGN in 33 galaxy clusters in the XMM-LSS field, up to redhift z=1.05. Previous studies have shown that the presence of X-ray selected AGN in rich galaxy clusters is suppressed. In the current study ... More
The cosmological analysis of X-ray cluster surveys: IV. Testing ASpiX with template-based cosmological simulationsOct 04 2017Feb 05 2018Following extensive tests on analytical toy-catalogues (paper III), we present the results of a more realistic study over a 711 deg2 template-based cosmological simulation. Dark matter halos from the Aardvark simulation have been ascribed luminosities, ... More
Another Approach to Juhl's Conformally Covariant Differential Operators from $S^n$ to $S^{n-1}$Dec 06 2016Apr 19 2017A family $({\mathbf D}_\lambda)_{\lambda\in \mathbb C}$ of differential operators on the sphere $S^n$ is constructed. The operators are conformally covariant for the action of the subgroup of conformal transformations of $S^n$ which preserve the smaller ... More
Optimized application of double and single layer BEM for in vivo conductivity estimationMar 24 2019Inter subject variability of the electrical conductivity of brain, skull and skin strongly limits the accuracy by which current sources underlying electro-encephalography (EEG) can be localized in the brain. This inter subject variability also constrains ... More
Symmetry breaking differential operators, the source operator and Rodrigues formulæFeb 16 2019A Rodrigues type formula for symbols of symmetry breaking differential operators is obtained in three situations : for the Rankin-Cohen operators, for the Juhl operators and for the conformally covariant bi-differential operators
Covariant bi-differential operators on matrix spaceJan 26 2016A family of bi-differential operators from $C^\infty\big(\Mat(m,\mathbb R)\times\Mat(m,\mathbb R)\big)$ into $C^\infty\big(\Mat(m,\mathbb R)\big)$ which are covariant for the projective action of the group $SL(2m,\mathbb R)$ on $\Mat(m,\mathbb R)$ is ... More
Singular conformally invariant trilinear forms, II The higher multiplicity casesJul 06 2015Let $S$ be the sphere of dimension $n-1, n\geq 4$. Let $(\pi_{\lambda})_{\lambda\in \mathbb C}$ be the scalar principle series of representations of the conformal group $SO_0(1,n)$, realized on $\mathcal C^\infty(S)$. For $\boldsymbol \lambda = (\lambda_1,\lambda_2,\lambda_3) ... More
Turbulence-induced rogue waves in Kerr resonatorsJan 09 2019Spontaneous emergence of self-organized patterns and their bifurcations towards a regime of complex dynamics in non-equilibrium dissipative systems is a paradigm of phase transition. Indeed, the behavior of these patterns in the highly nonlinear regime ... More
Angular correlation functions of X-ray point-like sources in the full exposure XMM-LSS fieldNov 25 2011Jan 18 2012Our aim is to study the large-scale structure of different types of AGN using the medium-deep XMM-LSS survey. We measure the two-point angular correlation function of ~ 5700 and 2500 X-ray point-like sources over the ~ 11 sq. deg. XMM-LSS field in the ... More
The XMM-LSS survey: the Class 1 cluster sample over the extended 11 deg$^2$ and its spatial distributionAug 27 2014This paper presents 52 X-ray bright galaxy clusters selected within the 11 deg$^2$ XMM-LSS survey. 51 of them have spectroscopic redshifts ($0.05<z<1.06$), one is identified at $z_{\rm phot}=1.9$, and all together make the high-purity "Class 1" (C1) cluster ... More
Conformal covariance for the powers of the Dirac operatorSep 17 2014A new proof of the conformal covariance of the powers of the flat Dirac operator is obtained. The proof uses their relation with the Knapp-Stein intertwining operators for the spinorial principal series. We also treat the compact picture, i.e. the corresponding ... More
Monte Carlo simulation of the transmission of measles: Beyond the mass action principleSep 10 2001Sep 13 2001We present a Monte Carlo simulation of the transmission of measles within a population sample during its growing and equilibrium states by introducing two different vaccination schedules of one and two doses. We study the effects of the contact rate per ... More
Mass Calibration of the CODEX Cluster Sample using SPIDERS Spectroscopy - I. The Richness-Mass RelationDec 14 2018We use galaxy dynamical information to calibrate the richness-mass scaling relation of a sample of 428 galaxy clusters that are members of the CODEX sample with redshifts up to z~0.7. These clusters were X-ray selected using the ROSAT All-Sky Survey (RASS), ... More
Statistical and Dynamical Study of Disease Propagation in a Small World NetworkJul 27 2001May 27 2003We study numerically statistical properties and dynamical disease propagation using a percolation model on a one dimensional small world network. The parameters chosen correspond to a realistic network of school age children. We found that percolation ... More
Singular conformally invariant trilinear forms and generalized Rankin Cohen operatorsApr 18 2011The most singular residues of the standard meromorphic family of trilinear conformally invariant forms on $\mathcal C^\infty_c(\mathbb R^d)$ are computed. Their expression involves covariant bidifferential operators (generalized Rankin Cohen operators), ... More
The XMM-LSS catalogue: X-ray sources and associated multiwavelength data. Version IINov 19 2012We present the final release of the multi-wavelength XMM-LSS data set,covering the full survey area of 11.1 square degrees, with X-ray data processed with the latest XMM-LSS pipeline version. The present publication supersedes the Pierre et al.(2007) ... More
The XXL Survey XXIV. The final detection pipelineSep 12 2018A well characterised detection pipeline is an important ingredient for X-ray cluster surveys. We present the final development of the XXL Survey pipeline. The pipeline optimally uses X-ray information by combining many overlapping observations of a source ... More
Classification and environmental properties of X-ray selected point-like sources in the XMM-LSS fieldJul 01 2013The XMM-Large Scale Structure survey, covering an area of 11.1 sq. deg., contains more than 6000 X-ray point-like sources detected with XMM-Newton down to a flux of 3x10^-15 erg s^-1 cm^-2 in the [0.5-2] keV band, the vast majority of which have optical ... More
Comparison of the properties of two fossil groups of galaxies with the normal group NGC 6034 based on multiband imaging and optical spectroscopyFeb 09 2012We collected multiband imaging and spectroscopy for two fossil groups (RX J1119.7+2126 and 1RXS J235814.4+150524) and one normal group (NGC 6034). We computed photometric redshifts in the central zones of each group, combining previous data with the SDSS ... More
Localized patterns and hole solutions in one-dimension extended sytemFeb 18 2005The existence, stability properties, and bifurcation diagrams of localized patterns and hole solutions in one-dimensional extended systems is studied from the point of view of front interactions. An adequate envelope equation is derived from a prototype ... More
Conformally invariant trilinear forms on the sphereJan 16 2010To each complex number $\lambda$ is associated a representation $\pi_\lambda$ of the conformal group $SO_0(1,n)$ on $\mathcal C^\infty(S^{n-1})$ (spherical principal series). For three values $\lambda_1,\lambda_2,\lambda_3$, we construct a trilinear form ... More
Primitive du cocycle de Maslov généraliséMar 21 2004Let $\mathcal{D}$ be a Hermitian symmetric space of tube type, and let $S$ be its Shilov boundary. We give a realization of the universal covering $\widetilde{S}$ of $S$. Then we describe on $\widetilde{S}$ a primitive for the generalized Maslov cocycle ... More
Transversal interface dynamics of a front connecting a stripe pattern to a uniform stateOct 11 2006Jun 05 2008Interfaces in two-dimensional systems exhibit unexpected complex dynamical behaviors, the dynamics of a border connecting a stripe pattern and a uniform state is studied. Numerical simulations of a prototype isotropic model, the subcritical Swift-Hohenberg ... More
Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation ThresholdSep 02 2002Sep 06 2002We study the imaginary part of the effective $ac$ conductivity as well as its distribution probability for vanishing losses in 2D composites. This investigation showed that the effective medium theory provides only informations about the average conductivity, ... More
Numerical heterodyne holography with two-dimensional photodetector arraysDec 21 2011We present an original heterodyne holography method for digital holography that relies on two-dimensional heterodyne detection to record the phase and the amplitude of a f ield. The technique has been tested on objects as much as 13 mm in size. Consistency ... More
Gradient theory of domain walls in thin, nematic liquid crystals filmsAug 31 2018In this paper we describe domain walls appearing in a thin, nematic liquid crystal sample subject to an external field with intensity close to the Fr\'eedericksz transition threshold. Using the gradient theory of the phase transition adopted to this situation, ... More
Bouncing localized structures in a liquid-crystal light-valve experimentDec 06 2005Experimental evidence of bouncing localized structures in a nonlinear optical system is reported.
Orbits of triples in the Shilov boundary of a bounded symmetric domainNov 10 2005Let ${\cal D}$ be a bounded symmetric domain of tube type, $S$ its Shilov boundary, and $G$ the neutral component of its group of biholomorphic transforms. We classify the orbits of $G$ in the set $S\times S\times S$.
The 2-10 keV unabsorbed luminosity function of AGN from the XMM-Newton LSS, CDFS and COSMOS surveysDec 17 2015Apr 07 2016The XMM-LSS, XMM-COSMOS, and XMM-CDFS surveys are complementary in terms of sky coverage and depth. Together, they form a clean sample with the least possible variance in instrument effective areas and PSF. Therefore this is one of the best samples available ... More
Distant galaxy clusters in the XMM Large Scale Structure surveyDec 17 2012(Abridged) Distant galaxy clusters provide important tests of the growth of large scale structure in addition to highlighting the process of galaxy evolution in a consistently defined environment at large look back time. We present a sample of 22 distant ... More
Additive Noise Induces Front PropagationNov 12 2004The propagation of a front connecting a stable homogeneous state with a stable periodic state in the presence of additive noise is studied. The mean velocity was computed both numerically and analitically. The numerics are in good agreement with the analitical ... More
Universal shape law of stochastic supercritical bifurcations: Theory and experimentsFeb 28 2007A universal law for the supercritical bifurcation shape of transverse one-dimensional (1D) systems in presence of additive noise is given. The stochastic Langevin equation of such systems is solved by using a Fokker-Planck equation leading to the expression ... More
Zero-calibration cVEP BCI using word prediction: a proof of conceptSep 21 2018Brain Computer Interfaces (BCIs) based on visual evoked potentials (VEP) allow for spelling from a keyboard of flashing characters. Among VEP BCIs, code-modulated visual evoked potentials (c-VEPs) are designed for high-speed communication . In c-VEPs, ... More
Symmetry breaking and restoration in the Ginzburg-Landau model of nematic liquid crystalsJun 09 2017In this paper we study qualitative properties of global minimizers of the Ginzburg-Landau energy which describes light-matter interaction in the theory of nematic liquid crystals near the Friedrichs transition. This model is depends on two parameters: ... More
Dissipation induced Instabilities and the Mechanical LaserMar 26 2001We study the 1:1 resonance for perturbed Hamiltonian systems with small dissipative and energy injection terms. These perturbations of the 1:1 resonance exhibit dissipation induced instabilities. This mechanism allow us to show that a slightly pumping ... More
Modelization of the Impedance Spectroscopy of composites by Electrical NetworksSep 02 2002Sep 06 2002We examined in this work the effect of the inter-grains distributions as well as the scaling of the complex impedance in order to analyze its frequency dependance for composite metal-insulator films. The dependance of the characteristic frequencies on ... More
Synthetic-aperture experiment in the visible with on-axis digital heterodyne holographyDec 23 2011We have developed a new on-axis digital holographic technique, heterodyne holography. The resolution of this technique is limited mainly by the amount of data recorded on two-dimensional photodetectors, i.e., the number of pixels and their size. We demonstrate ... More
Spin-transfer-driven nano-oscillators are equivalent to parametric resonatorsAug 12 2014Jan 12 2015The equivalence between different physical systems permits us to transfer knowledge between them and to characterize the universal nature of their dynamics. We demonstrate that a nanopillar driven by a spin-transfer torque is equivalent to a rotating ... More
Bisimulation for Feller-Dynkin ProcessesApr 01 2019Bisimulation is a concept that captures behavioural equivalence. It has been studied extensively on nonprobabilistic systems and on discrete-time Markov processes and on so-called continuous-time Markov chains. In the latter time is continuous but the ... More
Spontaneous motion of localized structures induced by parity symmetry transitionMar 27 2018We consider a paradigmatic nonvariational scalar Swift-Hohenberg equation that describes short wavenumber or large wavelength pattern forming systems. This work unveils evidence of the transition from stable stationary to moving localized structures in ... More
The XXL Survey VIII: MUSE characterisation of intracluster light in a z$\sim$0.53 cluster of galaxiesJan 04 2016Within a cluster, gravitational effects can lead to the removal of stars from their parent galaxies. Gas hydrodynamical effects can additionally strip gas and dust from galaxies. The properties of the ICL can therefore help constrain the physical processes ... More
The XXL Survey III. Luminosity-temperature relation of the Bright Cluster SampleDec 11 2015The XXL Survey is the largest homogeneous survey carried out with XMM-Newton. Covering an area of 50 deg$^{2}$, the survey contains several hundred galaxy clusters out to a redshift of $\approx$2 above an X-ray flux limit of $\sim$5$\times10^{-15}$ erg ... More
Active Galactic Nuclei and their Large-scale Structure: an eROSITA mock catalogueJan 30 2019In the context of the upcoming SRG/eROSITA survey, we present a methodology to construct mock catalogues for X-ray selected AGN samples based on dark matter only N-body simulations. We create a model that reproduces the observed hard X-ray AGN luminosity ... More
Synthetic simulations of the extragalactic sky seen by eROSITA. I. Pre-launch selection functions from Monte-Carlo simulationsJun 22 2018Studies of galaxy clusters provide stringent constraints on models of structure formation. Provided that selection effects are under control, large X-ray surveys are well suited to derive cosmological parameters, in particular those governing the dark ... More
The XXL Survey X: K-band luminosity - weak-lensing mass relation for groups and clusters of galaxiesDec 12 2015Dec 17 2015We present the K-band luminosity-halo mass relation, $L_{K,500}-M_{500,WL}$, for a subsample of 20 of the 100 brightest clusters in the XXL Survey observed with WIRCam at the Canada-France-Hawaii Telescope (CFHT). For the first time, we have measured ... More
Athena X-IFU synthetic observations of galaxy clusters to probe the chemical enrichment of the UniverseSep 24 2018Answers to the metal production of the Universe can be found in galaxy clusters, notably within their Intra-Cluster Medium (ICM). The X-ray Integral Field Unit (X-IFU) on board the next-generation European X-ray observatory Athena (2030s) will provide ... More
Pattern collapse as a mechanism for the formation of solitary structuresAug 29 2007We report a new mechanism for the formation of localized states, which takes place without front propagation. Correspondingly, localized structures appear as solitary states, displaying a behavior of single independent cells. The phenomenon is observed ... More
On localized vegetation patterns, fairy circles and localized patches in arid landscapesJan 16 2015We investigate the formation of localized structures with a varying width in one and two-dimensional systems. The mechanism of stabilization is attributed to strong nonlocal coupling mediated by a Lorentzian type of Kernel. We show that, in addition to ... More
The cosmological analysis of X-ray cluster surveys: I- A new method for interpreting number countsSep 20 2011May 10 2012We present a new method aiming to simplify the cosmological analysis of X-ray cluster surveys. It is based on purely instrumental observable quantities, considered in a two-dimensional X-ray colour-magnitude diagram (hardness ratio versus count-rate). ... More
Generalized Bernstein--Reznikov integralsJun 16 2009Jan 27 2010We find a closed formula for the triple integral on spheres in $\mathbb{R}^{2n}\times\mathbb{R}^{2n}\times\mathbb{R}^{2n}$ whose kernel is given by powers of the standard symplectic form. This gives a new proof to the Bernstein--Reznikov integral formula ... More
Conformally Covariant Bi-Differential Operators on a Simple Real Jordan AlgebraApr 06 2017For a simple real Jordan algebra $V,$ a family of bi-differential operators from $\mathcal{C}^\infty(V\times V)$ to $\mathcal{C}^\infty(V)$ is constructed. These operators are covariant under the rational action of the conformal group of $V.$ They generalize ... More
Conformally covariant bi-differential operators for differential formsSep 17 2018The classical Rankin-Cohen brackets are bi-differential operators from $C^\infty(\mathbb R)\times C^\infty(\mathbb R)$ into $ C^\infty(\mathbb R)$. They are covariant for the (diagonal) action of ${\rm SL}(2,\mathbb R)$ through principal series representations. ... More
Electromagnetic-induced fission of 238U projectile fragments, a test case for the production of spherical super-heavy nucleiOct 18 2002Isotopic series of 58 neutron-deficient secondary projectiles (205,206At, 205-209Rn, 208-212,217,218Fr, 211-223Ra, 215-226Ac, 221-229Th, 226-231Pa, 231-234U) were produced by projectile fragmentation using a 1 A GeV 238U beam. Cross sections of fission ... More
Continuous Forest Fire Propagation in a Local Small World Network ModelJun 30 2013This paper presents the development of a new continuous forest fire model implemented as a weighted local small-world network approach. This new approach was designed to simulate fire patterns in real, heterogeneous landscapes. The wildland fire spread ... More
Optical textures: characterizing spatiotemporal chaosJan 03 2016Jun 02 2016Macroscopic systems subjected to injection and dissipation of energy can exhibit complex spatiotemporal behaviors as result of dissipative self-organization. Here, we report a one and two dimensional pattern forming set up, which exhibits a transition ... More
SPIDERS: Selection of spectroscopic targets using AGN candidates detected in all-sky X-ray surveysApr 06 2017SPIDERS (SPectroscopic IDentification of eROSITA Sources) is an SDSS-IV survey running in parallel to the eBOSS cosmology project. SPIDERS will obtain optical spectroscopy for large numbers of X-ray-selected AGN and galaxy cluster members detected in ... More
Experimental observation of front propagation in LL model with negative diffractive and inhomogeneous Kerr cavityAug 10 2015A driven resonator with focusing Kerr nonlinearity shows stable localized structures in a region far from modulational instability. The stabilization mechanism is based on front interaction in bistable regime with an inhomogeneous injected field. The ... More
From localized spot to the formation of invaginated labyrinth structures in spatially extended systemsMay 21 2015The stability of a circular localized spot with respect to azimuthal perturbations is studied in in a variational Swift-Hohenberg model equation. The conditions under which the circular shape undergoes an elliptical deformation that transform it into ... More
Covariance matrices for halo number counts and correlation functionsApr 20 2011Jan 24 2012We study the mean number counts and two-point correlation functions, along with their covariance matrices, of cosmological surveys such as for clusters. In particular, we consider correlation functions averaged over finite redshift intervals, which are ... More
Particle Swarm Optimization for Mobility Load Balancing SON in LTE NetworksJan 26 2014This paper presents a self-optimizing solution for Mobility Load Balancing (MLB). The MLB-SON is performed in two phases. In the first, a MLB controller is designed using Multi-Objective Particle Swarm Optimization (MO-PSO) which incorporates a priori ... More
The symplectic area of a geodesic triangle in a Hermitian symmetric space of compact typeJan 21 2018Let $M$ be an irreducible Hermitian symmetric space of compact type, and let $\omega$ be its K\"ahler form. For a triplet $(p_1,p_2,p_3)$ of points in $M$ we study conditions under which a geodesic triangle $\mathcal T(p_1,p_2,p_3)$ with vertices $p_1,p_2,p_3$ ... More
Extended patchy ecosystems may increase their total biomass through self-replicationNov 28 2017Patches of vegetation consist of dense clusters of shrubs, grass, or trees, often found to be circular characteristic size, defined by the properties of the vegetation and terrain. Therefore, vegetation patches can be interpreted as localized structures. ... More
Zig-zag instability of an Ising wall in liquid crystalsApr 16 2001We present a theoretical explanation for the interfacial zigzag instability that appears in anisotropic systems. Such an instability has been experimentally highlighted for an Ising wall formed in a nematic liquid crystal cell under homeotropic anchoring ... More
Strong interaction between plants induces circular barren patches: fairy circlesJun 20 2013Vast landscapes extending from southern Angola, Namibia, and South Africa exhibit localised barren patches of vegetation called fairy circles. They consist of isolated or randomly distributed circular areas devoid of any vegetation. They are surrounded ... More
Dielectric resonances of lattice animals and other fractal structuresAug 20 1996Electrical and optical properties of binary inhomogeneous media are currently modelled by a random network of metallic bonds (conductance $\sigma_0$, concentration $p$) and dielectric bonds (conductance $\sigma_1$, concentration $1-p$). The macroscopic ... More
Berry phase of light Bragg-reflected by chiral liquid crystal mediaApr 17 2016Berry phase is revealed for circularly polarized light when it is Bragg-reflected by a chiral liquid crystal medium of the same handedness. By using a chiral nematic layer we demonstrate that if the input plane of the layer is rotated with respect to ... More
Jitter-Adaptive Dictionary Learning - Application to Multi-Trial Neuroelectric SignalsJan 16 2013Jun 24 2013Dictionary Learning has proven to be a powerful tool for many image processing tasks, where atoms are typically defined on small image patches. As a drawback, the dictionary only encodes basic structures. In addition, this approach treats patches of different ... More
The interaction of charged nanoparticles at interfacesApr 04 2015We study charged nanoparticles adsorbed onto surfactant bilayers using small-angle scattering of synchrotron radiation. The in-plane interaction of the particles is well described by a DLVO component (measured independently in solution) and a repulsive ... More
Connectivity of the Hexagonal, Cubic, and Isotropic Phases of the C$_{12}$EO$_6$/H$_2$O Lyotropic Mixture Investigated by Tracer Diffusion and X-ray ScatteringApr 09 2015The connectivity of the hydrophobic medium in the nonionic binary system C$_{12}$EO$_6$/H$_2$O is studied by monitoring the diffusion constants of tracer molecules at the transition between the hexagonal mesophase and the fluid isotropic phase. The increase ... More
The XXL survey XV: Evidence for dry merger driven BCG growth in XXL-100-GC X-ray clustersAug 03 2016The growth of brightest cluster galaxies is closely related to the properties of their host cluster. We present evidence for dry mergers as the dominant source of BCG mass growth at $z\lesssim1$ in the XXL 100 brightest cluster sample. We use the global ... More
Plant clonal morphologies and spatial patterns as self-organized responses to resource-limited environmentsAug 20 2014We propose here to interpret and model peculiar plant morphologies (cushions, tussocks) observed in the Andean altiplano as localized structures. Such structures resulting in a patchy, aperiodic aspect of the vegetation cover are hypothesized to self-organize ... More
Universal scaling of forest fire propagationMay 21 2008In this paper we use a variant of the Watts-Strogatz small-world model to predict wildfire behavior near the critical propagation/nonpropagation threshold. We find that forest fire patterns are fractal and that critical exponents are universal, which ... More
Theory of light-matter interaction in nematic liquid crystals and the second Painlevé equationOct 10 2016Oct 15 2016We study global minimizers of an energy functional arising as a thin sample limit in the theory of light-matter interaction in nematic liquid crystals. We show that depending on the parameters various defects are predicted by the model. In particular ... More
The XMM-LSS survey: optical assessment and properties of different X-ray selected cluster classesOct 29 2010XMM and Chandra opened a new area for the study of clusters of galaxies. Not only for cluster physics but also, for the detection of faint and distant clusters that were inaccessible with previous missions. This article presents 66 spectroscopically confirmed ... More
Localized states in bistable pattern forming systemsNov 24 2005Jan 30 2006We present an unifying description of a new class of localized states, appearing as large amplitude peaks nucleating over a pattern of lower amplitude. Localized states are pinned over a lattice spontaneously generated by the system itself. We show that ... More
Front propagation into unstable states in discrete mediaMay 02 2016Non-equilibrium dissipative systems usually exhibit multistability, leading to the presence of propagative domain between steady states. We investigate the front propagation into an unstable state in discrete media. Based on a paradigmatic model of coupled ... More
Upgrade of the Two-Screen Measurement Setup in the AWAKE ExperimentOct 03 2018The AWAKE project at CERN uses a self-modulated \SI{400}{GeV/c} proton bunch to drive GV/m wakefields in a \SI{10}{m} long plasma with an electron density of $n_{pe} = 7 \times 10^{14}\,\rm{electrons/cm}^3$. We present the upgrade of a proton beam diagnostic ... More
SPIDERS: the spectroscopic follow-up of X-ray selected clusters of galaxies in SDSS-IVAug 31 2016SPIDERS (The SPectroscopic IDentification of eROSITA Sources) is a program dedicated to the homogeneous and complete spectroscopic follow-up of X-ray AGN and galaxy clusters over a large area ($\sim$7500 deg$^2$) of the extragalactic sky. SPIDERS is part ... More
Slanted snaking bifurcation of localized Faraday wavesSep 02 2016We report on an experimental, theoretical and numerical study of slanted snaking of spatially localized parametrically excited waves on the surface of a water-surfactant mixture in a Hele-Shaw cell. We demonstrate experimentally the presence of a hysteretic ... More
Theory of light-matter interaction in nematic liquid crystals and the second Painlevé equationOct 10 2016We study global minimizers of an energy functional arising as a thin sample limit in the theory of light-matter interaction in nematic liquid crystals. We show that depending on the parameters various defects are predicted by the model. In particular ... More