Méthode temps-fréquence de séparation aveugle de sources basée sur la fonction de cohérence segmentée

- Nous introduisons dans ce papier une nouvelle méthode de séparation aveugle de sources (SAS) concernant les mélanges linéaires instantanés. Cette approche est basée sur l'analyse de la fonction de cohérence fréquentielle réelle des signaux observés, qui est segmentée temporellement et permet de détecter les zones temps-fréquence (TF) où une seule source est active. Par ailleurs, cette méthode suppose seulement que les sources sont non corrélées. L'identification des coefficients de séparation est réalisée par le calcul de rapports de densités spectrales de puissance des signaux mélangés, dans des zones TF mono-sources. Cette approche fournit de très bonnes performances pour des mélanges de signaux de parole et/ou de bruit, avec des améliorations de rapports signal/bruit (SNRI) de 40 à plus de 90 dB et des taux de reconnaissance automatique de la parole de 100 %

The MB2 gene family of Plasmodium species has a unique combination of S1 and GTP-binding domains

BACKGROUND: Identification and characterization of novel Plasmodium gene families is necessary for developing new anti-malarial therapeutics. The products of the Plasmodium falciparum gene, MB2, were shown previously to have a stage-specific pattern of subcellular localization and proteolytic processing. RESULTS: Genes homologous to MB2 were identified in five additional parasite species, P. knowlesi, P. gallinaceum, P. berghei, P. yoelii, and P. chabaudi. Sequence comparisons among the MB2 gene products reveal amino acid conservation of structural features, including putative S1 and GTP-binding domains, and putative signal peptides and nuclear localization signals. CONCLUSIONS: The combination of domains is unique to this gene family and indicates that MB2 genes comprise a novel family and therefore may be a good target for drug development

Geochemical Study of Natural CO2 Emissions in the French Massif Central: How to Predict Origin, Processes and Evolution of CO2 Leakage

International audienceThis study presents an overview of some results obtained within the French ANR (National Agency of Research) supported Géocarbone-Monitoring research program. The measurements were performed in Sainte-Marguerite, located in the French Massif Central. This site represents a natural laboratory for CO2/fluid/rock interactions studies, as well as CO2 migration mechanisms towards the surface. The CO2 leaking character of the studied area also allows to test and validate measurements methods and verifications for the future CO2 geological storage sites. During these surveys, we analyzed soil CO2 fluxes and concentrations. We sampled and analyzed soil gases, and gas from carbo-gaseous bubbling springs. A one-month continuous monitoring was also tested, to record the concentration of CO2 both in atmosphere and in the soil at a single point. We also developed a new methodology to collect soil gas samples for noble gas abundances and isotopic analyses, as well as carbon isotopic ratios. Our geochemical results, combined with structural geology, show that the leaking CO2 has a very deep origin, partially mantle derived. The gas rises rapidly along normal and strike-slip active faults. CO2 soil concentrations (also showing a mantle derived component) and CO2 fluxes are spatially variable, and reach high values. The recorded atmospheric CO2 is not very high, despite the important CO2 degassing throughout the whole area

PHOSPHORYLATION DES ANALOGUES DE NUCLEOTIDES ANTIRETROVIRAUX PAR LA NUCLEOSIDE DIPHOSPHATE KINASE

LES ANALOGUES DE NUCLEOTIDES ADMINISTRES DANS LES THERAPIES ANTIRETROVIRALES (DDN, AZT, D4T, 3TC) SONT TRANSFORMES DANS LA CELLULE EN TRIPHOSPHATE PAR DES KINASES CELLULAIRES AVANT D'ATTEINDRE LEUR CIBLE, LA TRANSCRIPTASE INVERSE DU VIRUS VIH. CETTE ACTIVATION IMPLIQUE LES ENZYMES DE LA VOIE DE RECUPERATION DES NUCLEOTIDES. LE DERNIER PHOSPHATE EST AJOUTE PAR LA NUCLEOSIDE DIPHOSPHATE (NDP) KINASE, VERITABLE ENZYME DE MENAGE, AVEC UNE SPECIFICITE LARGE POUR TOUS LES NUCLEOTIDES. LA REACTIVITE DE LA NDP KINASE AVEC LES ANALOGUES ANTIRETROVIRAUX S'EST AVEREE BEAUCOUP PLUS FAIBLE QUE SUPPOSEE. A L'AIDE D'UNE METHODE MESURANT LA FLUORESCENCE INTRINSEQUE DE LA PROTEINE, NOUS AVONS ETUDIE LA REACTIVITE DE L'ENZYME AVEC DIFFERENTS ANALOGUES DE NUCLEOTIDES DONNEUR (NTP) OU ACCEPTEUR (NDP) DE PHOSPHATE. BIEN QUE L'EQUILIBRE DE LA REACTION AVEC LES NTP ET NDP SOIT LE MEME QUE POUR LES NUCLEOTIDES NATURELS, LA VITESSE DE TRANSFERT DE PHOSPHATE EST TRES DIMINUEE (1000 A 10000 FOIS) POUR LES ANALOGUES ANTIVIRAUX, SUBSTRATS LENTS DE LA NDP KINASE. L'AFFINITE RELATIVE DES NTP A ETE MESUREE DIRECTEMENT POUR UN MUTANT INACTIF DE L'ENZYME. TOUS LES ANTIVIRAUX SE LIENT MOINS BIEN AU SITE ACTIF QUE LEURS HOMOLOGUES NATURELS A L'EXCEPTION DU D4T TRIPHOSPHATE QUI SE LIE A L'ENZYME AVEC LA MEME AFFINITE QUE LA THYMIDINE TRIPHOSPHATE. L'ABSENCE DE 3'OH SUR LE RIBOSE EMPECHE L'ETABLISSEMENT D'UNE LIAISON HYDROGENE INTRAMOLECULAIRE AVEC L'O 7 DU PHOSPHATE , CRUCIALE POUR UNE CATALYSE EFFICACE. SEUL LE D4T EST CAPABLE D'EFFECTUER PARTIELLEMENT UNE INTERACTION DE CE TYPE. C'EST LE MEILLEUR ANTIVIRAL PHOSPHORYLE PAR LA NDP KINASE. L'EXAMEN DE LA STRUCTURE D'UN NUCLEOTIDE LIE AU SITE ACTIF MONTRE QUE L'OXYGENE PRO-RP DU PHOSPHATE DU NUCLEOTIDE N'INTERAGIT NI AVEC LE MG 2 +, NI AVEC LA PROTEINE. EN COLLABORATION AVEC L'UNITE DE CHIMIE ORGANIQUE DE L'INSTITUT PASTEUR, UN GROUPEMENT BORANO (-BH 3) A ETE INTRODUIT A LA PLACE DE CET OXYGENE. LES DERIVES RP-BH 3 DE L'AZT ET DU D4T DI- ET TRIPHOSPHATE SONT DIX FOIS MIEUX PHOSPHORYLES PAR LA NDP KINASE, EN RAISON DE LEUR MEILLEURE AFFINITE POUR L'ENZYME. LE DIASTEREOISOMERE RP EST AUSSI UN MEILLEUR TERMINATEUR DE CHAINE DE L'ACTIVITE TRANSCRIPTASE INVERSE : LES NUCLEOTIDES -BORANO SONT PLUS EFFICACEMENT INCORPORES DANS L'ADN VIRAL. ILS SONT EGALEMENT MOINS SENSIBLES A L'EXCISION (PYROPHOSPHOROLYSE) PAR L'ENZYME SAUVAGE COMME PAR DES VARIANTS RESISTANTS DE LA POLYMERASE VIRALE. A CAUSE DU ROLE ESSENTIEL DE LA FONCTION 3'OH DU NUCLEOTIDE, NOUS AVONS ESSAYE DE COMPENSER SON ABSENCE DANS LES ANALOGUES ANTIVIRAUX EN INTRODUISANT UNE FONCTION - OH DANS LE SITE ACTIF DE LA NDP KINASE. PLUSIEURS MUTANTS ONT ETE CREES PAR MUTAGENESE DIRIGEE : UN SEUL MUTANT POUR LEQUEL L'ASN 119 A ETE SUBSTITUEE PAR UNE SER PHOSPHORYLE MIEUX LES ANTIVIRAUX AVEC UNE EFFICACITE CATALYTIQUE ENTRE DEUX ET DIX FOIS SUPERIEURE, DUE A UNE FIXATION PLUS AISEE AU SITE ACTIF. L'INTRODUCTION DE LA SER EN 119 PERMET DE RESTAURER LE RESEAU DE LIAISONS HYDROGENE INDISPENSABLE AU TRANSFERT DE PHOSPHATE. EN PARALLELE, NOUS AVONS RECHERCHE DE NOUVEAUX INHIBITEURS DE LA NDP KINASE : L'ADENOSINE 3 PHOSPHATE 5 PHOSPHOSULFATE (PAPS) INHIBE L'ACTIVITE NDP KINASE AVEC UNE AFFINITE DE 10 M. L'ANALYSE DES COCRISTAUX DE L'ENZYME COMPLEXEE AVEC LE PAPS MONTRE QUE L'ANALOGUE DE NUCLEOTIDE SE LIE AU SITE ACTIF SELON UN MODE DIFFERENT DU NUCLEOTIDE NATUREL. LE PAPS REPRESENTE AINSI L'INHIBITEUR DE PLUS FORTE AFFINITE CONNU POUR CETTE ENZYME.PARIS-BIUSJ-Thèses (751052125) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocPARIS-BIUSJ-Physique recherche (751052113) / SudocSudocFranceF

Analysis of Distributed Arc-Consistency Algorithms

Consistency techniques can significantly reduce the search space of constraint satisfaction problems (CSP). In particular, arc-consistency algorithms, such as AC-3 [7], AC-4 [8] and AC-6 [2], have been designed. In [9], we presented DisAC-4, a coarse-grained parallel algorithm designed for distributed memory computer using message passing, which is a distributed version of AC-4. We extend here this result. We design DisAC-3 and DisAC-6. The communication scheme is also extended to allow communication during the propagation step of the consistency algorithms. All these algorithms were systematically experimented. An analysis of the different experiments shows that, as in the sequential case, DisAC-6 provides the best performance and that DisAC-3 outperforms DisAC-4 on most tests. All the distributed algorithms shows a linear speedup. This lead to the conclusion that DisAC-6 is a good candidate for distributed arc-consistency

Sonification of Colour and Depth in a Mobility Aid for Blind People

Presented at the 16th International Conference on Auditory Display (ICAD2010) on June 9-15, 2010 in Washington, DC.The See Color interface transforms a small portion of a colored video image into sound sources represented by spatialized musical instruments. Basically, the conversion of colors into sounds is achieved by quantization of the HSL color system. Our purpose is to provide visually impaired individuals with a capability of perception of the environment in real time. In this work the novelty is the simultaneous sonification of color and depth, depth being coded by sound rhythm. Our sonification model is illustrated by several experiments, such as: (1) detecting an open door in order to go out from the office; (2) walking in a hallway and looking for a blue cabinet; (3) walking in a hallway and looking for a red tee shirt; (4) moving outside and avoiding a parked car. Videos with sounds of experiments are available on http://www.youtube.com/guidobologna

Pairing Colored Socks and Following a Red Serpentine With Sounds of Musical Instruments

Presented at the 14th International Conference on Auditory Display (ICAD2008) on June 24-27, 2008 in Paris, France.The See ColOr interface transforms a small portion of a colored video image into sound sources represented by spatialized musical instruments. This interface aims at providing visually impaired people with a capability of perception of the environment. As a first step of this on-going project, the purpose is to verify the hypothesis that it is possible to use sounds from musical instruments to replace color. Compared to state of the art devices, a quality of the See ColOr interface is that it allows the user to receive a feed-back auditory signal from the environment and its colors, promptly. Two experiments based on a head mounted camera have been performed. The first experiment pertaining to object manipulation is based on the pairing of colored socks, while the second experiment is related to outdoor navigation with the goal of following a colored serpentine. The ``socks'' experiment demonstrated that seven blindfolded individuals were able to accurately match pairs of colored socks. The same participants successfully followed a red serpentine for more than 80 meters

Guiding the focus of attention of blind people with visual saliency

International audienceThe context of this work is the development of a mobility aid for visually impaired persons. We present here an original approach for a real time alerting system, based on the detection of visual salient parts in videos. The particularity of our approach lies in the use of a new feature map constructed from the depth gradient. A distance function is described, which takes into account both stereoscopic camera limitations and user's choices. We also report how we automatically estimate the contribution of conspicuity maps, which enables the unsupervised determination of the final saliency map. We demonstrate here that this additional depth-based feature map allows the system to detect salient regions with good accuracy in most situations, even in the presence of noisy disparity maps