Optimized Schwarz waveform relaxation for Primitive Equations of the ocean

In this article we are interested in the derivation of efficient domain decomposition methods for the viscous primitive equations of the ocean. We consider the rotating 3d incompressible hydrostatic Navier-Stokes equations with free surface. Performing an asymptotic analysis of the system with respect to the Rossby number, we compute an approximated Dirichlet to Neumann operator and build an optimized Schwarz waveform relaxation algorithm. We establish the well-posedness of this algorithm and present some numerical results to illustrate the method

Acousto-optical coherence tomography with a digital holographic detection scheme

Acousto-optical coherence tomography (AOCT) consists in using random phase jumps on ultrasound and light to achieve a millimeter resolution when imaging thick scattering media. We combined this technique with heterodyne off-axis digital holography. Two-dimensional images of absorbing objects embedded in scattering phantoms are obtained with a good signal-to-noise ratio. We study the impact of the phase modulation characteristics on the amplitude of the acousto-optic signal and on the contrast and apparent size of the absorbing inclusion

Stress-resistant plants and their production

The present invention relates to plant genes involved in negative regulation of resistance to biotic and/or abiotic stress and uses thereof. More particularly, the present invention relates to plants comprising an inactivated MADS-box gene function, and having increased resistance to biotic and/or abiotic stress. The invention also relates to methods for producing modified plants having increased resistance to fungal, bacterial pathogens and/or to drought stress. In particular, the invention relates to methods for producing plants with inactivated MAD26 gene, or an ortholog thereof, and exhibiting resistance to biotic and/or abiotic stress. (Résumé d'auteur

Evaluation de Techniques de Traitement des Refusés pour l'Octroi de Crédit

We present the problem of "Reject Inference" for credit acceptance. Because of the current legal framework (Basel II), credit institutions need to industrialize their processes for credit acceptance, including Reject Inference. We present here a methodology to compare various techniques of Reject Inference and show that it is necessary, in the absence of real theoretical results, to be able to produce and compare models adapted to available data (selection of "best" model conditionnaly on data). We describe some simulations run on a small data set to illustrate the approach and some strategies for choosing the control group, which is the only valid approach to Reject Inference

A multilayer Saint-Venant system with mass exchanges for Shallow Water flows. Derivation and numerical validation

The standard multilayer Saint-Venant system consists in introducing fluid layers that are advected by the interfacial velocities. As a consequence there is no mass exchanges between these layers and each layer is described by its height and its average velocity. Here we introduce another multilayer system with mass exchanges between the neighborhing layers where the unknowns are a total height of water and an average velocity per layer. We derive it from Navier-Stokes system with an hydrostatic pressure and prove energy and hyperbolicity properties of the model. We also give a kinetic interpretation leading to effective numerical schemes with positivity and energy properties. Numerical tests show the versatility of the approach and its ability to compute recirculation cases with wind forcing.Comment: Submitted to M2A

The use of fixed-term contracts and the labour adjustment in Belgium

This paper aims to document and analyse the use of fixed-term contracts (FTC) and to analyse the dynamics of labour adjustment by type of labour contract at the firm level, drawing on the detailed breakdown of both the labour force and labour entries and exits that are available in the "Belgian Firms' Social Balance Sheets" dataset. It also aims to investigate the structure of labour adjustment costs by type of labour contract, using the methodology proposed by Goux, Maurin and Pauchet (2001). Results first indicate that flexible labour contracts are not only used to facilitate short-term labour adjustment but also as a screening device. The findings also suggest that when a firm decides to introduce flexible labour into its production process, it does also this to meet long-run objectives such as implementing minimising costs innovations. It is further estimated that the introduction of FTCs does not seem to affect the speed of indefinite-term contracts (ITC) adjustment. Our results also tend to indicate that the FTC is a key adjustment variable in response to cost shocks and to unexpected demand fluctuations while, in response to expected fluctuations in output, firms then prefer to adjust their level of permanent employment. Finally, and as far as the structure of labour adjustment costs in Belgium is concerned, the marginal recruitment cost under an ITC represents 12.4% of the marginal termination cost of ITC, while the marginal cost associated with the recruitment under an FTC only accounts for 0.8% of its ITC counterpar

Mesurer la similarité structurelle entre réseaux lexicaux

International audienceIn this paper, we compare the topological structure of lexical networks with a method based on randomwalks. Instead of characterising pairs of vertices according only to whether they are connected or not, we measure theirstructural proximity by evaluating the relative probability of reaching one vertex from the other via a short random walk.This proximity between vertices is the basis on which we can compare the topological structure of lexical networks be-cause it outlines the similar dense zones of the graphs.Dans cet article, nous comparons la structure topologique des réseaux lexicaux avec une méthode fondée sur des marches aléatoires. Au lieu de caractériser les paires de sommets selon un critère binaire de connectivité, nous mesurons leur proximité structurelle par la probabilité relative d'atteindre un sommet depuis l'autre par une courte marche aléatoire. Parce que cette proximité rapproche les sommets d'une même zone dense en arêtes, elle permet de comparer la structure topologique des réseaux lexicaux

Approche bayésienne pour l'estimation d'indices de Sobol

International audienceLe problème considéré est l'estimation des indices de Sobol du premier ordre d'une fonction réelle $f$ coûteuse à évaluer, à partir d'un nombre réduit d'évaluations. Nous nous intéressons à la loi a posteriori de ces indices, lorsque $f$ est modélisée par un processus gaussien. Nous montrons qu'il peut être risqué de procéder à une estimation de ces distributions par une approche de type plug-in pour les hyperparamètres du processus gaussien --- l'incertitude sur ces hyperparamètres pouvant constituer une part importante de l'incertitude sur les indices de Sobol --- et qu'il est préférable d'employer une approche complétement bayésienne. Nos propos sont illustrés sur un exemple académique, puis sur un cas-test issu de l'électronique de puissance

Role of LRR-RLKS in stress response and developmental processes through systematic K.O. analysis in rice

The function of a small number of Leucine-Rich Repeat Receptor-Like Kinase (LRR-RLK) genes has been studied, mostly in Arabidopsis thaliana. They are involved in several important biological processes, including development, resistance/defence and adaptation to biotic and abiotic stresses. We are interested in deciphering the function of these genes in rice. In this aim, we decided to take advantage of the availability of T-DNA and Tos17 insertion mutant libraries of rice cv. Nipponbare to start a systematic screen of knock-out mutants of these genes. The rice genome contains ~320 LRRRLK genes. Our search in international collections of insertion mutant lines which are catalogued by Flanking Sequence Tag (FST) information from most of the rice insertional mutagenesis projects around the world revealed that 238 insertional mutant lines are available for the 323 genes. Phenotypical evaluation of homozygous mutants is performed under various biotic and abiotic stresses and mutant plants are observed for phenotypes at several stages of growth, from seedlings in Petri dishes to flowering and grain development stages in the greenhouse. Thus, with this project, we aim first to decipher and explore new genes involved in defence and developmental responses to stresses. Second, our analysis will be of great benefit to provide potential targets for cereal improvement, notably in the breeding of drought-tolerant and pathogen-resistant crops. This project is supported by grant #ANR-08-GENM-021 from Agence Nationale de la recherche (ANR), France. (Résumé d'auteur

Invariants and variability of synonymy networks: Self mediated agreement by confluence

International audienceEdges of graphs that model real data can beseen as judgements whether pairs of objectsare in relation with each other or not. So,one can evaluate the similarity of two graphswith a measure of agreement between judgesclassifying pairs of vertices into two cate-gories (connected or not connected). Whenapplied to synonymy networks, such measuresdemonstrate a surprisingly low agreement be-tween various resources of the same language.This seems to suggest that the judgementson synonymy of lexemes of the same lexi-con radically differ from one dictionary ed-itor to another. In fact, even a strong dis-agreement between edges does not necessarilymean that graphs model a completely differ-ent reality: although their edges seem to dis-agree, synonymy resources may, at a coarsergrain level, outline similar semantics. To in-vestigate this hypothesis, we relied on sharedcommon properties of real world data net-works to look at the graphs at a more globallevel by using random walks. They enabledus to reveal a much better agreement betweendense zones than between edges of synonymygraphs. These results suggest that althoughsynonymy resources may disagree at the levelof judgements on single pairs of words, theymay nevertheless convey an essentially simi-lar semantic information