Le livre, une espèce en danger ?

La prolifération d’une espèce peut, on le sait, masquer la disparition de quantités d’autres et se retourner, in fine, contre elle-même. La bibliodiversité est ce concept par lequel, perçue comme un écosystème, la pensée se révèle fragile, tributaire d’un biotope largement contaminé par les OGM du prêt-à-penser..

Floating polygon soup

International audienceThis paper presents a new representation called floating polygon soup for applications like 3DTV and FTV (Free Viewpoint Television). This representation is based on 3D polygons and takes as input MVD data. It extends the previously proposed polygon soup representation which is appropriate for both compression, transmission and rendering stages. The floating polygon soup conserves these advantages while also taking into account misalignments at the view synthesis stage due to modeling errors. The idea for reducing these misalignments is to morph the 3D geometry depending on the current viewpoint. Results show that artifacts in virtual views are reduced and objective quality is increased

Compact quad-based representation for 3D video

International audienceThe context of this study is 3D video. Starting from a sequence of multi-view video plus depth (MVD) data, the proposed quad-based representation takes into account, in a unified manner, different issues such as compactness, compression, and intermediate view synthesis. The representation is obtained into two steps. Firstly, a set of 3D quads is extracted by using a quadtree decomposition of the depth maps. Secondly, a selective elimination of the quads is performed in order to reduce inter-view redundancies and thus provide a compact representation. Experiments on two real sequences show good quality results at the rendering stage and a small data overload compared to mono-view video

Surface plasmon polaritons in multilayer jellium systems:Dispersion and spatial description

Surface-plasmon polaritons (SPPs) are electromagnetic waves that propagate along metal-dielectric interfaces, with important applications in sensing, energy, and nanotechnology. While the behavior of SPPs in single metal slabs is well understood, the coupling between plasmon modes in multilayer systems has received less attention. In this paper, we explore the response functions of SPPs in single-slab, double-slab, and two-different-slab systems using the jellium model. Thanks to a comparison with classical models, in this paper, we reveal how quantum effects influence the resonance frequencies of these modes. We also detail the spatial description of the different SPP modes and unveil how their coupling occurs in two-different-slab systems. These findings provide insights into the behavior of SPPs, especially in complex nanostructures

Recalage GPS / SIG / Video, et synthèse de textures de bâtiments

National audienceDans le contexte du recalage de données SIG de bâtiments avec des vidéos -- par exemple pour des applications de réalité augmentée -- nous présentons une solution à un des problèmes les plus critiques, à savoir l'initialisation de ce recalage. La méthode proposée exploite d'une part les informations sémantiques que l'on peut associer aux primitives extraites des images, et d'autre part le principe même de l'algorithme robuste RANSAC pour trouver automatiquement la pose initiale de la caméra d'acquisition. Nous montrons également comment ce recalage peut être exploité pour enrichir la base SIG visualisée par des textures réelles, calculées à partir des images acquises au sol, et ce de façon tout aussi automatique

Spontaneous and radiation-induced chromosomal instability and persistence of chromosome aberrations after radiotherapy in lymphocytes from prostate cancer patients

The aim of the study was to compare the spontaneous and ex vivo radiation-induced chromosomal damage in lymphocytes of untreated prostate cancer patients and age-matched healthy donors, and to evaluate the chromosomal damage, induced by radiotherapy, and its persistence. Blood samples from 102 prostate cancer patients were obtained before radiotherapy to investigate the excess acentric fragments and dicentric chromosomes. In addition, in a subgroup of ten patients, simple exchanges in chromosomes 2 and 4 were evaluated by fluorescent in situ hybridization (FISH), before the onset of therapy, in the middle and at the end of therapy, and 1 year later. Data were compared to blood samples from ten age-matched healthy donors. We found that spontaneous yields of acentric chromosome fragments and simple exchanges were significantly increased in lymphocytes of patients before onset of therapy, indicating chromosomal instability in these patients. Ex vivo radiation-induced aberrations were not significantly increased, indicating proficient repair of radiation-induced DNA double-strand breaks in lymphocytes of these patients. As expected, the yields of dicentric and acentric chromosomes, and the partial yields of simple exchanges, were increased after the onset of therapy. Surprisingly, yields after 1 year were comparable to those directly after radiotherapy, indicating persistence of chromosomal instability over this time. Our results indicate that prostate cancer patients are characterized by increased spontaneous chromosomal instability. This instability seems to result from defects other than a deficient repair of radiation-induced DNA double-strand breaks. Radiotherapy-induced chromosomal damage persists 1 year after treatment

Radiosensitivity in breast cancer assessed by the Comet and micronucleus assays

Spontaneous and radiation-induced genetic instability of peripheral blood mononuclear cells derived from unselected breast cancer (BC) patients (n=50) was examined using the single-cell gel electrophoresis (Comet) assay and a modified G2 micronucleus (MN) test. Cells from apparently healthy donors (n=16) and from cancer patients (n=9) with an adverse early skin reaction to radiotherapy (RT) served as references. Nonirradiated cells from the three tested groups exhibited similar baseline levels of DNA fragmentation assessed by the Comet assay. Likewise, the Comet analysis of in vitro irradiated (5 Gy) cells did not reveal any significant differences among the three groups with respect to the initial and residual DNA fragmentation, as well as the DNA repair kinetics. The G2 MN test showed that cells from cancer patients with an adverse skin reaction to RT displayed increased frequencies of both spontaneous and radiation-induced MN compared to healthy control or the group of unselected BC patients. Two patients from the latter group developed an increased early skin reaction to RT, which was associated with an increased initial DNA fragmentation in vitro only in one of them. Cells from the other BC patient exhibited a striking slope in the dose–response curve detected by the G2 MN test. We also found that previous RT strongly increased both spontaneous and in vitro radiation-induced MN levels, and to a lesser extent, the radiation-induced DNA damage assessed by the Comet assay. These data suggest that clinical radiation may provoke genetic instability and/or induce persistent DNA damage in normal cells of cancer patients, thus leading to increased levels of MN induction and DNA fragmentation after irradiation in vitro. Therefore, care has to be taken when blood samples collected postradiotherapeutically are used to assess the radiosensitivity of cancer patients

Spermatozoal sensitive biomarkers to defective protaminosis and fragmented DNA

Human sperm DNA damage may have adverse effects on reproductive outcome. Infertile men possess substantially more spermatozoa with damaged DNA compared to fertile donors. Although the extent of this abnormality is closely related to sperm function, the underlying etiology of ensuing male infertility is still largely controversial. Both intra-testicular and post-testicular events have been postulated and different mechanisms have been proposed to explain the presence of damaged DNA in human spermatozoa. Three among them, i.e. abnormal chromatin packaging, oxidative stress and apoptosis, are the most studied and discussed in the present review. Furthermore, results from numerous investigations are presented, including our own findings on these pathological conditions, as well as the techniques applied for their evaluation. The crucial points of each methodology on the successful detection of DNA damage and their validity on the appraisal of infertile patients are also discussed. Along with the conventional parameters examined in the standard semen analysis, evaluation of damaged sperm DNA seems to complement the investigation of factors affecting male fertility and may prove an efficient diagnostic tool in the prediction of pregnancy outcome

GASCON : Gestion agro-écologique de la santé des cultures et des organismes nuisibles

Le croisement des sciences agronomiques, de l’écologie appliquée à la gestion des agroécosystèmes,et des sciences humaines et sociales, qu’implique la transition agroécologique, pose de nouveaux défis pour répondre aux enjeux agricoles: intégrer des connaissances de différentes disciplines et produites à différentes échelles d’organisation pour agir en situation; développer des cadres d’analyse et démarches intégrant la diversité de situations à gérer par les acteurs et permettant de construire des réponses adaptées à chaque situation; et concevoir et mettre en œuvre des pratiques d’enseignement et d’apprentissage, qui dotent les apprenants de capacités à penser leur action en contexte, en mobilisant des savoirs et savoir-faire multiples en termes de contenus disciplinaires et des savoir-être pour construire des solutions avec une diversité d’acteurs. Dans le champ de la formation, ces défis nécessitent dès lors de revisiter les contenus des enseignements dispensés, les modalités pédagogiques et les dispositifs de formation existants, de manière à appréhender au mieux la complexité des processus à l’œuvre. Pour autant, peu de travaux s’attardent sur les modalités pratiques de ce changement et de ses implications, alors même que de nombreuses initiatives en matière de pédagogie et d’agroécologie se développent ces dernières années. L’objectif de ce séminaire est de promouvoir une information partagée et l’échange d’expériences pour répondre aux enjeux posés par l’agroécologie dans la formation (transversalité, pluridisciplinarité, approche systémique, pédagogies actives). Ces enjeux peuvent se décliner suivant plusieurs entrées : les thématiques enseignées (agriculture, élevage, territoire, alimentation, ...); les pratiques et les dispositifs pédagogiques mis en œuvre pour aborder ces questions (enseignement numérique, dispositifs expérimentaux, projets professionnels, référentiels, ...);les publics d’apprenants: élèves, étudiants, professionnels, ..