Approximation d'images par minimisation d'une distance géométrique appliquée à un modèle d'éléments finis 3D

Ce papier présente un modèle géométrique pour le codage d'images, permettant un échantillonnage adaptatif, et se présentant sous la forme d'une structure de maillage 3D de type éléments finis. Nous avons défini une distance géométrique caractérisant l'erreur entre l'image originale et son modèle et développé un algorithme de gradient efficace permettant une déformation adéquate du modèle. Le rendu 2D résultant constitue une représentation performante en terme de qualité subjective, offrant une bonne restitution des caractéristiques visuellement importantes

Suivi d'Objets vidéo par maillage hiérarchique

La représentation d'objets vidéo par maillages triangulaires a récemment été ajoutée à la norme MPEG-4. Les fonctionnalités attendues sont nombreuses : compression, interpolation spatio-temporelle, réalité augmentée, animation et déformation de textures, indexation basée contenu. Pour qu'elles soient efficaces, des techniques performantes d'estimation de mouvement doivent être mises en oeuvre, associées à maillages adaptés. Cet article expose un procédé de suivi d'objets vidéo maillés à partir d'une unique segmentation initiale. S'appuyant sur une représentation par maillage hiérarchique, nous allons successivement estimer le mouvement dominant de l'objet au moyen d'un modèle global affine, puis estimer les mouvements locaux de chacun des noeuds du maillage. Cette dernière étape exploite complètement le caractère hiérarchique de la méthode dans le sens qu'autant d'estimations successives que de niveaux de maillages sont réalisées. Le résultat est un suivi efficace à la fois des mouvement globaux et locaux, ne s'appuyant pas sur les alpha-plans des séquences MPEG-4, ni sur une segmentation spatiale associée. Le procédé d'estimation de mouvement est de type différentiel, basé sur la minimisation de la fonction quadratique d'erreur de compensation

Streptococcus agalactiae clones infecting humans were selected and fixed through the extensive use of tetracycline

Streptococcus agalactiae (Group B Streptococcus, GBS) is a commensal of the digestive and genitourinary tracts of humans that emerged as the leading cause of bacterial neonatal infections in Europe and North America during the 1960s. Due to the lack of epidemiological and genomic data, the reasons for this emergence are unknown. Here we show by comparative genome analysis and phylogenetic reconstruction of 229 isolates that the rise of human GBS infections corresponds to the selection and worldwide dissemination of only a few clones. The parallel expansion of the clones is preceded by the insertion of integrative and conjugative elements conferring tetracycline resistance (TcR). Thus, we propose that the use of tetracycline from 1948 onwards led in humans to the complete replacement of a diverse GBS population by only few TcR clones particularly well adapted to their host, causing the observed emergence of GBS diseases in neonates. \ua9 2014 Macmillan Publishers Limited. All rights reserved

Low Clinical Burden of 2009 Pandemic Influenza A (H1N1) Infection during Pregnancy on the Island of La Réunion

BACKGROUND: Pregnant women have been identified as a group at risk, both for respiratory complications than for the admissions to the Intensive Care Unit (ICU) during the 2009 H1N1 influenza pandemic (pdm). The purpose of this prospective register-based cohort-study was to characterize the clinical virulence of the pdm (H1N1/09)v during pregnancy in La Réunion. METHODS/PRINCIPAL FINDINGS: Over a twelve-week pdm wave (13 July to 3 October 2009), 294 pregnant women presented with an influenza-like illness (ILI) to one of the three maternity departments of the South Reunion area, Indian Ocean. Out of these, 278 were checked by RT-PCR for influenza viruses (157 positive and 121 negative, of whom, 141 with pdm flu and 132 with ILIs of non pdm origin, 5 untyped). The median body temperature was higher in women experiencing pdm flu than in those with non pdm ILI (38.9 degrees C versus 38.3 degrees C, P<0.0001), without evidence linked to circulating viremia. Oseltamivir was given for 86% of pdm flu cases in a median time inferior than 48 hrs (range 0-7 days). The hospitalization rate for pdm flu was of 60% and not associated with underlying conditions. Six viral pneumonia and fourteen asthma attacks were observed among 84 hospitalized pdm flu cases, of whom, only one led to the ICU for an acute lung injury. No maternal death occurred during the pdm wave. None adverse pregnancy outcome was associated with pdm flu. No congenital birth defect, nor early-onset neonatal influenza infection was attributable to pdm flu exposure. CONCLUSIONS/SIGNIFICANCE: This report mitigates substantially the presumed severity of pandemic H1N1/09 influenza infection during pregnancy. The reasons for which the clinical burden of H1N1/09 influenza virus may differ worldwide raise questions about a differential local viral-strain effect and public health preparedness, notably in timely access to special care and antiviral treatments

Investigation of Association between PFO Complicated by Cryptogenic Stroke and a Common Variant of the Cardiac Transcription Factor GATA4

Patent foramen ovale (PFO) is associated with clinical conditions including cryptogenic stroke, migraine and varicose veins. Data from studies in humans and mouse suggest that PFO and the secundum form of atrial septal defect (ASDII) exist in an anatomical continuum of septal dysmorphogenesis with a common genetic basis. Mutations in multiple members of the evolutionarily conserved cardiac transcription factor network, including GATA4, cause or predispose to ASDII and PFO. Here, we assessed whether the most prevalent variant of the GATA4 gene, S377G, was significantly associated with PFO or ASD. Our analysis of world indigenous populations showed that GATA4 S377G was largely Caucasian-specific, and so subjects were restricted to those of Caucasian descent. To select for patients with larger PFO, we limited our analysis to those with cryptogenic stroke in which PFO was a subsequent finding. In an initial study of Australian subjects, we observed a weak association between GATA4 S377G and PFO/Stroke relative to Caucasian controls in whom ASD and PFO had been excluded (OR = 2.16; p = 0.02). However, in a follow up study of German Caucasians no association was found with either PFO or ASD. Analysis of combined Australian and German data confirmed the lack of a significant association. Thus, the common GATA4 variant S377G is likely to be relatively benign in terms of its participation in CHD and PFO/Stroke