Results for "Didier Stricker"

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Surface Defect Classification in Real-Time Using Convolutional Neural NetworksApr 07 2019Surface inspection systems are an important application domain for computer vision, as they are used for defect detection and classification in the manufacturing industry. Existing systems use hand-crafted features which require extensive domain knowledge ... More
Fast and Efficient Depth Map Estimation from Light FieldsMay 01 2018The paper presents an algorithm for depth map estimation from the light field images in relatively small amount of time, using only single thread on CPU. The proposed method improves existing principle of line fitting in 4-dimensional light field space. ... More
CNN based Patch Matching for Optical Flow with Thresholded Hinge LossJul 27 2016Learning based approaches have not yet achieved their full potential in optical flow estimation, where their performance still trails heuristic approaches. In this paper, we present a novel optical flow pipeline that uses patch-matching with CNN trained ... More
Flow Fields: Dense Correspondence Fields for Highly Accurate Large Displacement Optical Flow EstimationAug 21 2015Oct 20 2015Modern large displacement optical flow algorithms usually use an initialization by either sparse descriptor matching techniques or dense approximate nearest neighbor fields. While the latter have the advantage of being dense, they have the major disadvantage ... More
Learning quadrangulated patches for 3D shape parameterization and completionSep 20 2017We propose a novel 3D shape parameterization by surface patches, that are oriented by 3D mesh quadrangulation of the shape. By encoding 3D surface detail on local patches, we learn a patch dictionary that identifies principal surface features of the shape. ... More
Learning Quadrangulated Patches For 3D Shape ProcessingMar 25 2019We propose a system for surface completion and inpainting of 3D shapes using generative models, learnt on local patches. Our method uses a novel encoding of height map based local patches parameterized using 3D mesh quadrangulation of the low resolution ... More
Accurate 3D Reconstruction of Dynamic Scenes from Monocular Image Sequences with Severe OcclusionsDec 20 2017The paper introduces an accurate solution to dense orthographic Non-Rigid Structure from Motion (NRSfM) in scenarios with severe occlusions or, likewise, inaccurate correspondences. We integrate a shape prior term into variational optimisation framework. ... More
Dense Scene Flow from Stereo Disparity and Optical FlowAug 30 2018Scene flow describes 3D motion in a 3D scene. It can either be modeled as a single task, or it can be reconstructed from the auxiliary tasks of stereo depth and optical flow estimation. While the second method can achieve real-time performance by using ... More
Structured 2D Representation of 3D Data for Shape ProcessingMar 25 2019We represent 3D shape by structured 2D representations of fixed length making it feasible to apply well investigated 2D convolutional neural networks (CNN) for both discriminative and geometric tasks on 3D shapes. We first provide a general introduction ... More
CNN-based Patch Matching for Optical Flow with Thresholded Hinge LossJul 27 2016Nov 18 2016Learning based approaches have not yet achieved their full potential in optical flow estimation, where their performance still trails heuristic approaches. In this paper, we present an optical flow pipeline that uses patch matching with CNN trained features ... More
Scalable Dense Monocular Surface ReconstructionOct 17 2017This paper reports on a novel template-free monocular non-rigid surface reconstruction approach. Existing techniques using motion and deformation cues rely on multiple prior assumptions, are often computationally expensive and do not perform equally well ... More
Flow Fields: Dense Correspondence Fields for Highly Accurate Large Displacement Optical Flow EstimationMar 07 2017Oct 28 2018Modern large displacement optical flow algorithms usually use an initialization by either sparse descriptor matching techniques or dense approximate nearest neighbor fields. While the latter have the advantage of being dense, they have the major disadvantage ... More
DeLiO: Decoupled LiDAR OdometryApr 29 2019Most LiDAR odometry algorithms estimate the transformation between two consecutive frames by estimating the rotation and translation in an intervening fashion. In this paper, we propose our Decoupled LiDAR Odometry (DeLiO), which -- for the first time ... More
Simultaneous Hand Pose and Skeleton Bone-Lengths Estimation from a Single Depth ImageDec 08 2017Articulated hand pose estimation is a challenging task for human-computer interaction. The state-of-the-art hand pose estimation algorithms work only with one or a few subjects for which they have been calibrated or trained. Particularly, the hybrid methods ... More
CNN-based Patch Matching for Optical Flow with Thresholded Hinge Embedding LossJul 27 2016May 18 2017Learning based approaches have not yet achieved their full potential in optical flow estimation, where their performance still trails heuristic approaches. In this paper, we present a CNN based patch matching approach for optical flow estimation. An important ... More
HDM-Net: Monocular Non-Rigid 3D Reconstruction with Learned Deformation ModelMar 27 2018Monocular dense 3D reconstruction of deformable objects is a hard ill-posed problem in computer vision. Current techniques either require dense correspondences and rely on motion and deformation cues, or assume a highly accurate reconstruction (referred ... More
PWOC-3D: Deep Occlusion-Aware End-to-End Scene Flow EstimationApr 12 2019In the last few years, convolutional neural networks (CNNs) have demonstrated increasing success at learning many computer vision tasks including dense estimation problems such as optical flow and stereo matching. However, the joint prediction of these ... More
Combining Stereo Disparity and Optical Flow for Basic Scene FlowJan 15 2018Scene flow is a description of real world motion in 3D that contains more information than optical flow. Because of its complexity there exists no applicable variant for real-time scene flow estimation in an automotive or commercial vehicle context that ... More
FlowFields++: Accurate Optical Flow Correspondences Meet Robust InterpolationMay 09 2018Optical Flow algorithms are of high importance for many applications. Recently, the Flow Field algorithm and its modifications have shown remarkable results, as they have been evaluated with top accuracy on different data sets. In our analysis of the ... More
Fast View Synthesis with Deep Stereo VisionApr 25 2018May 07 2018Novel view synthesis is an important problem in computer vision and graphics. Over the years a large number of solutions have been put forward to solve the problem. However, the large-baseline novel view synthesis problem is far from being "solved". Recent ... More
Structure from Articulated Motion: An Accurate and Stable Monocular 3D Reconstruction Approach without Training DataMay 12 2019Recovery of articulated 3D structure from 2D observations is a challenging computer vision problem with many applications. Current learning-based approaches achieve state-of-the-art performance on public benchmarks but are limited to the specific types ... More
SDC - Stacked Dilated Convolution: A Unified Descriptor Network for Dense Matching TasksApr 05 2019Dense pixel matching is important for many computer vision tasks such as disparity and flow estimation. We present a robust, unified descriptor network that considers a large context region with high spatial variance. Our network has a very large receptive ... More
SceneFlowFields++: Multi-frame Matching, Visibility Prediction, and Robust Interpolation for Scene Flow EstimationFeb 26 2019State-of-the-art scene flow algorithms pursue the conflicting targets of accuracy, run time, and robustness. With the successful concept of pixel-wise matching and sparse-to-dense interpolation, we push the limits of scene flow estimation. Avoiding strong ... More
Learning 3D Shapes as Multi-Layered Height-maps using 2D Convolutional NetworksJul 23 2018Jul 26 2018We present a novel global representation of 3D shapes, suitable for the application of 2D CNNs. We represent 3D shapes as multi-layered height-maps (MLH) where at each grid location, we store multiple instances of height maps, thereby representing 3D ... More
IsMo-GAN: Adversarial Learning for Monocular Non-Rigid 3D ReconstructionApr 27 2019The majority of the existing methods for non-rigid 3D surface regression from monocular 2D images require an object template or point tracks over multiple frames as an input, and are still far from real-time processing rates. In this work, we present ... More
Fast Feature Extraction with CNNs with Pooling LayersMay 08 2018In recent years, many publications showed that convolutional neural network based features can have a superior performance to engineered features. However, not much effort was taken so far to extract local features efficiently for a whole image. In this ... More
SceneFlowFields: Dense Interpolation of Sparse Scene Flow CorrespondencesOct 27 2017While most scene flow methods use either variational optimization or a strong rigid motion assumption, we show for the first time that scene flow can also be estimated by dense interpolation of sparse matches. To this end, we find sparse matches across ... More
An Empirical Evaluation Study on the Training of SDC Features for Dense Pixel MatchingApr 12 2019Training a deep neural network is a non-trivial task. Not only the tuning of hyperparameters, but also the gathering and selection of training data, the design of the loss function, and the construction of training schedules is important to get the most ... More
Quantifying impacts of short-term plasticity on neuronal information transferApr 15 2012Short-term changes in efficacy have been postulated to enhance the ability of synapses to transmit information between neurons, and within neuronal networks. Even at the level of connections between single neurons, direct confirmation of this simple conjecture ... More
DeepHPS: End-to-end Estimation of 3D Hand Pose and Shape by Learning from Synthetic DepthAug 28 2018Articulated hand pose and shape estimation is an important problem for vision-based applications such as augmented reality and animation. In contrast to the existing methods which optimize only for joint positions, we propose a fully supervised deep network ... More
Meson supercurrents and the Meissner effect in the Sakai-Sugimoto modelNov 21 2008May 22 2009The Sakai-Sugimoto model provides a holographic description for chiral symmetry breaking. We use this model to investigate chirally broken phases in an external magnetic field at finite isospin and baryon chemical potentials. The equations of motion for ... More
Multiframe Scene Flow with Piecewise Rigid MotionOct 05 2017We introduce a novel multiframe scene flow approach that jointly optimizes the consistency of the patch appearances and their local rigid motions from RGB-D image sequences. In contrast to the competing methods, we take advantage of an oversegmentation ... More
Using Learning-based Filters to Detect Rule-based Filtering ObsolescenceJul 07 2000For years, Caisse des Depots et Consignations has produced information filtering applications. To be operational, these applications require high filtering performances which are achieved by using rule-based filters. With this technique, an administrator ... More
Scalar field collapse with negative cosmological constantOct 13 2014Jun 09 2015The formation of black holes or naked singularities is studied in a model in which a homogeneous time-dependent scalar field with an exponential potential couples to four dimensional gravity with negative cosmological constant. An analytic solution is ... More
Efficient resolution of the Colebrook equationOct 30 2008A robust, fast and accurate method for solving the Colebrook-like equations is presented. The algorithm is efficient for the whole range of parameters involved in the Colebrook equation. The computations are not more demanding than simplified approximations, ... More
XTRA: The fast X-ray timing detector on XEUSJan 08 2004The Rossi X-ray Timing Explorer (RXTE) has demonstrated that the dynamical variation of the X-ray emission from accreting neutron stars and stellar mass black holes is a powerful probe of their strong gravitational fields. At the same time, the X-ray ... More
Homogenizing metamaterials, three timesNov 08 2012The homogenization of a metamaterial made of a collection of scatterers periodically disposed is studied from three different points of view. Specifically tools for multiple scattering theory, functional analysis, differential geometry and optimization ... More
Soft lags in neutron star kHz Quasi Periodic Oscillations: evidence for reverberation?Mar 04 2013Apr 20 2013High frequency soft reverberation lags have now been detected from stellar mass and super massive black holes. Their interpretation involves reflection of a hard source of photons onto an accretion disk, producing a delayed reflected emission, with a ... More
A quantum way for metamaterialsMar 07 2011Mar 09 2011A new future for metamaterials is suggested, involving the insertion of quantum degrees of freedom, under the guise of quantum dots or cold atoms, in an photonic matrix. It is argued that new emergent, quantum, properties could be obtained.
On the Herman-Kluk Semiclassical ApproximationAug 06 2009For a subquadratic symbol $H$ on $\R^d\times\R^d = T^*(\R^d)$, the quantum propagator of the time dependent Schr\"odinger equation $i\hbar\frac{\partial\psi}{\partial t} = \hat H\psi$ is a Semiclassical Fourier-Integral Operator when $\hat H=H(x,\hbar ... More
Non linear eigenvalue problemsDec 06 2004In this paper we consider generalized eigenvalue problems for a family of operators with a polynomial dependence on a complex parameter. This problem is equivalent to a genuine non self-adjoint operator. We discuss here existence of non trivial eigenstates ... More
ECLAIRs: A microsatellite to observe the prompt optical and X-ray emission of Gamma-Ray BurstsMay 21 2002ECLAIRs is a French microsatellite devoted to the observation of the prompt optical and X-ray emission of GRBs. For about 100 GRBs/yr, independent of their duration, ECLAIRs will provide high time resolution high sensitivity spectral coverage from a few ... More
Poles and zeros of the scattering matrix associated to defect modesMar 08 2000We analyze electromagnetic waves propagation in one-dimensional periodic media with single or periodic defects. The study is made both from the point of view of the modes and of the diffraction problem. We provide an explicit dispersion equation for the ... More
Large deviations and portfolio optimizationFeb 05 1998Jun 08 1998Risk control and optimal diversification constitute a major focus in the finance and insurance industries as well as, more or less consciously, in our everyday life. We present a discussion of the characterization of risks and of the optimization of portfolios ... More
Confidence intervals for nonhomogeneous branching processes and polymerase chain reactionsMar 29 2005We extend in two directions our previous results about the sampling and the empirical measures of immortal branching Markov processes. Direct applications to molecular biology are rigorous estimates of the mutation rates of polymerase chain reactions ... More
Maximal generalization of Baum-Katz theorem and optimality of sequential testsOct 03 2005Baum-Katz theorem asserts that the Cesaro means of i.i.d. increments distributed like X r-converge if and only if |X|^{r+1} is integrable. We generalize this, and we unify other results, by proving that the following equivalence holds, if and only if ... More
Some control design experiments with HIFOOSep 01 2006A new MATLAB package called HIFOO was recently proposed for H-infinity fixed-order controller design. This document illustrates how some standard controller design examples can be solved with this software.
Low-lying zeros of L-functions for Quaternion AlgebrasOct 30 2018The density conjecture of Katz and Sarnak predicts that, for natural families of L-functions, the distribution of zeros lying near the real axis is governed by a group of symmetry. In the case of the universal family of automorphic forms of bounded analytic ... More
Optimization of brain and life performance: Striving for playing at the top for the long runNov 20 2011In this essay written with my students and collaborators in mind, I share simple recipes that are easy and often fun to put in practice and that make a big difference in one's life. The seven guiding principles are: (1) sleep, (2) love and sex, (3) deep ... More
Semidefinite representation of convex hulls of rational varietiesJan 13 2009Jan 28 2011Using elementary duality properties of positive semidefinite moment matrices and polynomial sum-of-squares decompositions, we prove that the convex hull of rationally parameterized algebraic varieties is semidefinite representable (that is, it can be ... More
On semidefinite representations of plane quarticsSep 10 2008Sep 22 2008This note focuses on the problem of representing convex sets as projections of the cone of positive semidefinite matrices, in the particular case of sets generated by bivariate polynomials of degree four. Conditions are given for the convex hull of a ... More
Le logo du CNRS est-il convexe ?Oct 17 2008In october 2008, CNRS adopts a new logo with a round shape. We study the mathematical representation of this shape, and in particular its convexity.
Exact diagonalisation studies of strongly correlated 2D lattice fermionsSep 14 1994The T=0 phase diagram of the planar t--J model with small doping is investigated by exact diagonalisations of square clusters with up to 32 sites. At half-filling, the single hole quasi-particule weight vanishes in the strong correlation limit $J\rightarrow ... More
On the Internal Structure of the Singlet d$_{X^2-Y^2}$ Hole Pair in an AntiferromagnetJun 10 1993Exact diagonalizations of two dimensional small t--J clusters reveal dominant hole-hole correlations at distance $\sqrt{2}$ (ie between holes on next nearest neighbor sites). A new form of singlet $d_{x^2-y^2}$ pair operator is proposed to account for ... More
Binding of holes and pair spectral function in the t-J modelMar 17 1993Clusters of the two-dimensionnal t--J model with 2 holes and up to 26 sites are diagonalized using a Lanczos algorithm. The behaviour of the binding energy with system size suggests the existence of a finite critical value of J above which binding occurs ... More
Exotic Mott phases of the extended t--J model on the checkerboard lattice at commensurate densitiesMay 29 2007Coulomb repulsion between electrons moving on a frustrated lattice can give rise, at simple commensurate electronic densities, to exotic insulating phases of matter. Such a phenomenon is illustrated using an extended t--J model on a planar pyrochlore ... More
On two duality properties of random walks in random environment on the integer lineOct 03 2005According to Comets, Gantert and Zeitouni on the one hand and to Derriennic on the other hand, some functionals associated to the hitting times of random walks in random environment on the integer line coincide, for the walk itself and for the walk in ... More
Accretion flows around stellar mass black holes and neutron starsJan 08 2004In this review, I summarize the main X-ray/hard X-ray properties of the accretion flows around black holes and neutron stars based on recent broad-band spectral and timing observations performed by the BeppoSAX and Rossi X-ray Timing Explorer satellites. ... More
Anomalous Quantum Diffusion and Conductivity of QuasicrystalsDec 07 1999A phenomenological diffusion law $L(t)\propto t^{\beta}$, where L(t) measures the spreading of a wave-packet in a time t, is assumed for perfect quasicrystals. We show that it affects their conductivity with striking differences compared to the case of ... More
On Cayley graphs of algebraic structuresMar 22 2018We present simple graph-theoretic characterizations of Cayley graphs for left-cancellative monoids, groups, left-quasigroups and quasigroups. We show that these characterizations are effective for the end-regular graphs of finite degree.
On the Cauchy problem for higher-order nonlinear dispersive equationsAug 27 2007We study a class of higher-order KdV equations. We show that the associated initial value problem is well posed in weighted Besov and Sobolev spaces for small initial data. We also prove ill-posedness results when in H^s(\R), for any real s.
On convexity of the frequency response of a stable polynomialSep 07 2007In the complex plane, the frequency response of a univariate polynomial is the set of values taken by the polynomial when evaluated along the imaginary axis. This is an algebraic curve partitioning the plane into several connected components. In this ... More
Semidefinite geometry of the numerical rangeMar 25 2010The numerical range of a matrix is studied geometrically via the cone of positive semidefinite matrices (or semidefinite cone for short). In particular it is shown that the feasible set of a two-dimensional linear matrix inequality (LMI), an affine section ... More
Numerical computation of resonance poles in scattering theoryMar 30 2001We present a possible way of computing resonance poles and modes in scattering theory. Numerical examples are given for the scattering of electromagnetic waves by finite-size photonic crystals.
Enhanced pairing in doped quantum magnets with frustrating hole motionApr 18 2004Jul 10 2004Evidence for strong pairing at arbitrary small J/t is provided in a t-J model on the checkerboard lattice for the sign of hopping leading to frustration in hole motion. Destructive quantum interferences suppress Nagaoka ferromagnetism when J->0 and reduce ... More
The broad band X-ray/hard X-ray spectra of accreting neutron starsJan 17 2001I review the energy spectra of low mass X-ray binaries (LMXBs) containing weakly magnetized accreting neutron stars (NS), emphasizing the most recent broad band (0.1-200 keV) spectral and timing observations performed by Beppo-SAX and RXTE. Drawing on ... More
Discrete scale invariance and complex dimensionsJul 01 1997Dec 17 1998We discuss the concept of discrete scale invariance and how it leads to complex critical exponents (or dimensions), i.e. to the log-periodic corrections to scaling. After their initial suggestion as formal solutions of renormalization group equations ... More
Pinczon AlgebrasNov 12 2012After recalling the construction of a graded Lie bracket on the space of cyclic multilinear forms on a vector space V, due to Georges Pinczon and Rosane Ushirobira, we prove this construction gives a structure of quadratic associative algebra, up to homotopy, ... More
Harmonic continuous-time branching momentsNov 02 2005Feb 14 2007We show that the mean inverse populations of nondecreasing, square integrable, continuous-time branching processes decrease to zero like the inverse of their mean population if and only if the initial population $k$ is greater than a first threshold $m_1\ge1$. ... More
Time Evolution of States for Open Quantum Systems. The quadratic caseAug 08 2012Nov 16 2012Our main goal in this paper is to extend to any system of coupled quadratic Hamiltonians some properties known for systems of quantum harmonic oscillators related with the Brownian Quantum Motion model. In a first part we get a rather general formula ... More
Automated Scene Flow Data Generation for Training and VerificationAug 30 2018Aug 31 2018Scene flow describes the 3D position as well as the 3D motion of each pixel in an image. Such algorithms are the basis for many state-of-the-art autonomous or automated driving functions. For verification and training large amounts of ground truth data ... More
Efficient erasure decoding of Reed-Solomon codesJan 14 2009We present a practical algorithm to decode erasures of Reed-Solomon codes over the q elements binary field in O(q \log_2^2 q) time where the constant implied by the O-notation is very small. Asymptotically fast algorithms based on fast polynomial arithmetic ... More
X-ray Timing beyond the Rossi X-ray Timing ExplorerJun 05 2006With its ability to look at bright galactic X-ray sources with sub-millisecond time resolution, the Rossi X-ray Timing Explorer (RXTE) discovered that the X-ray emission from accreting compact stars shows quasi-periodic oscillations on the dynamical timescales ... More
Stability of Inhomogeneous Superstructures from Renormalized Mean-field Theory of the t--J ModelMar 10 2005Apr 16 2005Using the t--J model (which can also include Coulomb repulsion) and the ``plain vanilla'' renormalized mean-field theory of Zhang et al. (1988), stability of inhomogeneous 4a x 4a superstructures as those observed in cuprates superconductors around hole ... More
Asymptotics of iterated branching processesOct 03 2005We study the iterated Galton-Watson process (IGW), possibly with thinning, introduced by Gawe{\l}and Kimmel to model the number of repeats of DNA triplets during some genetic disorders. If the process involves some thinning, then extinction and explosion ... More
Harmonic moments of non homogeneous branching processesOct 03 2005We study the harmonic moments of Galton-Watson processes, possibly non homogeneous, with positive values. Good estimates of these are needed to compute unbiased estimators for non canonical branching Markov processes, which occur, for instance, in the ... More
Invariance principle for the coverage rate of genomic physical mappingsOct 03 2005We study some stochastic models of physical mapping of genomic sequences. Our starting point is a global construction of the process of the clones and of the process of the anchors which are used to map the sequence. This yields explicit formulas for ... More
Counting and Equidistribution for Quaternion AlgebrasOct 05 2018Dec 26 2018We aim at studying automorphic forms of bounded analytic conductor in the division quaternion algebra setting. We prove the equidistribution of the universal family with respect to an explicit and geometrically meaningful measure. It leads to answering ... More
Semidefinite geometry of the numerical rangeDec 09 2008The numerical range of a matrix is studied geometrically via the cone of positive semidefinite matrices (or semidefinite cone for short). In particular it is shown that the feasible set of a two-dimensional linear matrix inequality (LMI), an affine section ... More
Structural characterization of Cayley graphsSep 27 2016We show that the directed labelled Cayley graphs coincide with the rooted deterministic vertex-transitive simple graphs. The Cayley graphs are also the strongly connected deterministic simple graphs of which all vertices have the same cycle language, ... More
Asymptotics of posteriors for binary branching processesJun 06 2008We compute the posterior distributions of the initial population and parameter of binary branching processes, in the limit of a large number of generations. We compare this Bayesian procedure with a more na\"ive one, based on hitting times of some random ... More
kHz QPOs from the 2000 and 2010 X-ray transients located in the globular cluster Terzan 5: EXO1745-248 and IGR J17480-2446May 02 2012EXO1745-248 is a transient neutron star low-mass X-ray binary located in the globular cluster Terzan 5. It was in outburst in 2000 and displayed during one Rossi X-ray Timing Explorer observation a highly coherent quasi-periodic oscillation (QPO) at frequencies ... More
Properties of holons in the Quantum Dimer ModelNov 14 2007Jan 22 2008I introduce a doped two-dimensional quantum dimer model describing a doped Mott insulator and retaining the original Fermi statistics of the electrons. This model shows a rich phase diagram including a d-wave hole-pair unconventional superconductor at ... More
Out-of-equilibrium Correlated Systems : Bipartite Entanglement as a Probe of ThermalizationNov 09 2010Apr 18 2011Thermalization play a central role in out-of-equilibrium physics of ultracold atoms or electronic transport phenomena. On the other hand, entanglement concepts have proven to be extremely useful to investigate quantum phases of matter. Here, it is argued ... More
Nurturing Breakthroughs: Lessons from Complexity TheoryJun 13 2007A general theory of innovation and progress in human society is outlined, based on the combat between two opposite forces (conservatism/inertia and speculative herding "bubble" behavior). We contend that human affairs are characterized by ubiquitous ``bubbles'', ... More
Detecting rigid convexity of bivariate polynomialsJan 23 2008Given a polynomial $x \in {\mathbb R}^n \mapsto p(x)$ in $n=2$ variables, a symbolic-numerical algorithm is first described for detecting whether the connected component of the plane sublevel set ${\mathcal P} = \{x : p(x) \geq 0\}$ containing the origin ... More
Direct evidence of negative refraction at media with negative ε and μNov 15 2002We analyze wave scattering by an interface between a positive refractive index medium and a Left-Handed Material. We show that the negative refraction effect can be deduced directly from Maxwell equations, without references to causality or losses.
Comment on ''Photonic Band Gaps: Noncommuting limit and the 'Acoustic Band'''Apr 25 2001This comment concerns the homogenization of 2D dielectric photonic crystals, and the fact that the limits $k\to 0$ ($k$ is the Bloch vector) and $\epsilon \to +\infty $ do not commute for $p$-polarized waves
Entanglement spectra of quantum Heisenberg laddersMay 12 2010Jun 29 2010Bipartite entanglement measures are fantastic tools to investigate quantum phases of correlated electrons. Here, I analyze the entanglement spectrum of **gapped** two-leg quantum Heisenberg ladders on a periodic ribbon partitioned into two identical periodic ... More
Dragon-Kings, Black Swans and the Prediction of CrisesJul 24 2009We develop the concept of ``dragon-kings'' corresponding to meaningful outliers, which are found to coexist with power laws in the distributions of event sizes under a broad range of conditions in a large variety of systems. These dragon-kings reveal ... More
On Cayley graphs of basic algebraic structuresMar 15 2019We present simple graph-theoretic characterizations of Cayley graphs for monoids, semigroups and groups. We extend these characterizations to commutative monoids, semilattices, and abelian groups.
Holographic thermalization patternsMar 11 2014We investigate the behaviour of various correlators in N=4 super Yang Mills theory, taking finite coupling corrections into account. In the thermal limit we investigate the flow of the quasinormal modes as a function of the 't Hooft coupling. Then by ... More
Numerical simulation of artificial microswimmers driven by Marangoni flowFeb 11 2017Mar 07 2017In the present paper the behavior of a single artificial microswimmer is addressed, namely an active droplet moving by Marangoni flow. The non-uniform surface tension distribution underlying the propulsion mechanism of the droplet, is generated by a non-uniform ... More
Novel Calibration Method for Switched Capacitor Arrays Enables Time Measurements with Sub-Picosecond ResolutionMay 20 2014Nov 21 2014Switched capacitor arrays (SCA) ASICs are becoming more and more popular for the readout of detector signals, since the sampling frequency of typically several gigasamples per second allows excellent pile-up rejection and time measurements. They suffer ... More
Two Steps Feature Selection and Neural Network Classification for the TREC-8 RoutingJul 11 2000For the TREC-8 routing, one specific filter is built for each topic. Each filter is a classifier trained to recognize the documents that are relevant to the topic. When presented with a document, each classifier estimates the probability for the document ... More
Gravitational collapse of thin shells: Time evolution of the holographic entanglement entropyFeb 04 2015Mar 31 2015We study the dynamics of gravitationally collapsing massive shells in AdS spacetime, and show in detail how one can determine extremal surfaces traversing them. The results are used to solve the time evolution of the holographic entanglement entropy in ... More
Universality in holographic entropy productionMay 27 2014Jun 04 2014We consider the time evolution of two entropy-like quantities, the holographic entanglement entropy and causal holographic information, in a model of holographic thermalization dual to the gravitational collapse of a thin planar shell. Unlike earlier ... More
Practical Model-Based Diagnosis with Qualitative Possibilistic UncertaintyFeb 20 2013An approach to fault isolation that exploits vastly incomplete models is presented. It relies on separate descriptions of each component behavior, together with the links between them, which enables focusing of the reasoning to the relevant part of the ... More
Simulations of pure and doped low-dimensional spin-1/2 gapped systemsAug 16 2004Low dimensional spin-1/2 systems with antiferromagnetic interactions display very innovative features, driven by strong quantum fluctuations. In particular, geometrical effects or competing magnetic interactions can give rise to the formation of a spin ... More
Log-periodic Oscillations for Biased Diffusion in 3D Random LatticesDec 07 1997Dec 27 1997Random walks with a fixed bias direction on randomly diluted cubic lattices far above the percolation threshold exhibit log-periodic oscillations in the effective exponent versus time. A scaling argument accounts for the numerical results in the limit ... More