Physical modelling of the airflow-walls interactions to understand the sleep apnea syndrome

Sleep Apnea Syndrome (SAS) is defined as a partial or total closure of the patient upper airways during sleep. The term "collapsus" (or collapse) is used to describe this closure. From a fluid mechanical point of view, this collapse can be understood as a spectacular example of fluid-walls interaction. Indeed, the upper airways are delimited in their largest part by soft tissues having different geometrical and mechanical properties: velum, tongue and pharyngeal walls. Airway closure during SAS comes from the interaction between these soft tissues and the inspiratory flow. The aim of this work is to understand the physical phenomena at the origin of the collapsus and the metamorphosis in inspiratory flow pattern that has been reported during SAS. Indeed, a full comprehension of the physical conditions allowing this phenomenon is a prerequisite to be able to help in the planning of the surgical gesture that can be prescribed for the patients. The work presented here focuses on a simple model of fluid-walls interactions. The equations governing the airflow inside a constriction are coupled with a Finite Element (FE) biomechanical model of the velum. The geometries of this model is extracted from a single midsagittal radiography of a patient. The velar deformations induced by airflow interactions are computed, presented, discussed and compared to measurements collected onto an experimental setup

The closest extrasolar planet: A giant planet around the M4 dwarf Gl 876

High precision radial velocity observations of the nearby M4 dwarf Gl 876 with the Observatoire de Haute Provence 1.93 m telescope and the new 1.20 m swiss telescope at la Silla indicate the presence of a jovian mass companion to this star. The orbital fit to the data gives a period of 60.8 days, a velocity amplitude of 246 m/s and an eccentricity of 0.34. Assuming that Gl 876 has a mass of 0.3 solar masses, the mass function implies a mass for the companion of 2/sin(i) Jupiter masses.Comment: 4 pages LaTeX, Accepted for publication in A&A Letters. Some sections improved or clarified after referee's comment

Distribution and conservation of Banana Streak Virus (BSV) within banana Musa balbisiana genome: what impact on host and virus evolution ?

The nuclear genome of several plants isinvaded by numerous viral sequences. These integrations correspond to accidental events mainly resulting from illegitimate recombination of DNA viruses belonging to the family Caulimoviridae with plant DNA whereas integration into the host genome is not required for viral replication. These integrations are for the most part defective as a result of pseudogenisation driven by the host genome evolution. Conversely some, named infectious, could release a functional viral genome following activating stresses. Our aim is to study the evolving integration context of such infectious integrants for Banana streak virus among the diversity of the banana B genome in order to retrace the evolutionary BSV story and understand their impact on host and virus evolution in terms of cost/benefit. To answer this question, we propose to characterize the infectious integrants (eBSV) among a representative sampling of Musa balbisiana diversity and to hypothesize a contribution of eBSV towards plant virus resistance through an RNA interfering mechanism versus virus maintain through interspecific crosses. (Texte intégral

Distribution and conservation of Banana Streak Virus (BSV) within banana Musa balbisiana genome : what impact on host and virus evolution ?

The nuclear genome of several plants isinvaded by numerous viral sequences. These integrations correspond to accidental events mainly resulting from illegitimate recombination of DNA viruses belonging to the family Caulimoviridae with plant DNA whereas integration into the host genome is not required for viral replication. These integrations are for the most part defective as a result of pseudogenisation driven by the host genome evolution. Conversely some, named infectious, could release a functional viral genome following activating stresses. Our aim is to study the evolving integration context of such infectious integrants for Banana streak virus among the diversity of the banana B genome in order to retrace the evolutionary BSV story and understand their impact on host and virus evolution in terms of cost/benefit. To answer this question, we propose to characterize the infectious integrants (eBSV) among a representative sampling of Musa balbisiana diversity and to hypothesize a contribution of eBSV towards plant virus resistance through an RNA interfering mechanism versus virus maintain through interspecific crosses. (Texte intégral

La relativité du facteur d'impact en recherche agronomique

Le facteur d'impact (= FI) d'une revue est un indicateur couramment utilisé pour l'évaluation de la production scientifique d'une équipe ou d'un organisme de recherche. La valeur de cet indicateur dépend de divers paramètres comme l'année de publication ou le champ disciplinaire (= subject category). De ce fait, les revues à facteur d'impact sont réparties par Thomson-ISI en 171 champs disciplinaires, une revue pouvant être répertoriée dans un ou plusieurs champs disciplinaires. Le Cirad, mène ses activités de recherche dans le domaine de l'agronomie tropicale. Le mode de représentation en box plots, ou boîtes à moustaches, appliqué aux 17 champs disciplinaires identifiés pour la majorité des articles publiés par le Cirad dans les revues à facteurs d'impact, permet d'illustrer la relativité de la valeur du facteur d'impact selon ces disciplines. Ce mode de représentation permet aussi: 1- d'identifier, pour certaines disciplines, des valeurs de FI hors normes, appelées outliers; 2- de montrer que la notoriété d'une revue, vue sous l'angle des FI, dépend du champ disciplinaire dans lequel celle-ci est étudiée, et 3- de constater que des comparaisons, hors champs disciplinaires, des valeurs brutes des FI peuvent conduire à des interprétations abusives. [Résumé d'auteur

How eBSV polymorphism could enlighten BSV and banana evolution story?

The nuclear genome of banana plants is invaded by numerous viral sequences of banana streak viruses (BSV), a DNA virus belonging to the family Caulimoviridae. These integrations are mostly defective as a result of pseudogenisation driven by the host genome evolution. Conversely some named infectious, can release a functional viral genome following activating stresses. We characterized the infectious endogenous BSV (eBSV) for three BSV species (BSOLV, BSGFV and BSImV) present within the Musa balbisiana B genome of the seedy diploid Pisang Klutuk Wulung (PKW). Our aim is to study PKW-related BSV integrations among the diversity of the banana B genomes in order to retrace the evolutionary BSV and banana stories We extended on purpose the M. balbisiana diversity by the addition of interspecific hybrids with M. acuminata showing different levels of ploidy for the B genome (ABB, AAB, AB) of the banana sample in order to include unsampled or extinct M. balbisiana ressources. We also based the analysis referring to the two areas of sympatry between M. acuminata and M. balbisiana and the centers of origin for the most largely cultivated AAB cultivars. One was in India and the other one in East Asia going from Philippines to New Guinea (Perrier et al, 2009). We characterized the PKW-related eBSV allelic polymorphism using PCR markers (described in poster Galzi & Duroy et al.) and Southern blots on 77 accessions. We codified the results of Southern blot and PCR in order to calculate a common dissimilarity matrix and interpret the eBSV distribution. As a result, three dendrograms of PKW-related eBSV made with the Neighbor Joining (NJ) method on the 77 banana accessions, for each BSV species, are presented as well as one dendogram resulting of NJ analysis for the three BSV species all together . We show that the known phylogeny of banana accessions can enlighten the eBSV structure diversity and that eBSV polymorphisms can help to understand the particularly unresolved M. balbisiana diversity. An evolutionary scheme of BSV/eBSV banana evolution will be proposed. (Texte intégral