University of Bordeaux

About: University of Bordeaux is a education organization based out in Bordeaux, France. It is known for research contribution in the topics: Population & Laser. The organization has 28811 authors who have published 55536 publications receiving 1619635 citations. The organization is also known as: UB.

A dual-frequency sub-arcsecond study of proto-planetary disks at mm wavelengths: first evidence for radial variations of the dust properties

Abstract: Context. Proto-planetary disks are thought to provide the initial environment for planetary system formation. The dust and gas distribution and its evolution with time is one of the key elements in the process.Aims. We attempt to characterize the radial distribution of dust in disks around a sample of young stars from an observational point of view, and, when possible, in a model-independent way, by using parametric laws.Methods. We used the IRAM PdBI interferometer to provide very high angular resolution (down to 0.4′′ in some sources) observations of the continuum at 1.3 mm and 3 mm around a sample of T Tauri stars in the Taurus-Auriga region. The sample includes single and multiple systems, with a total of 23 individual disks. We used track-sharing observing mode to minimize the biases. We fitted these data with two kinds of models: a “truncated power law” model and a model presenting an exponential decay at the disk edge (“viscous” model).Results. Direct evidence for tidal truncation is found in the multiple systems. The temperature of the mm-emitting dust is constrained in a few systems. Unambiguous evidence for large grains is obtained by resolving out disks with very low values of the dust emissivity index β . In most disks that are sufficiently resolved at two different wavelengths, we find a radial dependence of β , which appears to increase from low values (as low as 0) at the center to about 1.7−2 at the disk edge. The same behavior could apply to all studied disks. It introduces further ambiguities in interpreting the brightness profile, because the regions with apparent β ≈ 0 can also be interpreted as being optically thick when their brightness temperature is high enough. Despite the added uncertainty on the dust absorption coefficient, the characteristic size of the disk appears to increase with a higher estimated star age. Conclusions. These results provide the first direct evidence of the radial dependence of the grain size in proto-planetary disks. Constraints of the surface density distributions and their evolution remain ambiguous because of a degeneracy with the β (r ) law.

Successes and limitations of phytotechnologies at field scale: outcomes, assessment and outlook from COST Action 859

Abstract: Purpose : Many agricultural and brownfield soils are polluted and more have become marginalised due to the introduction of new, risk-based legislation. The European Environment Agency estimates that there are at least 250,000 polluted sites in the member states that require urgent remedial action. There is also significant volumes of wastewaters and dredged polluted sediments. Phytotechnologies potentially offer a cost-effective in situ alternative to conventional technologies for remediation of low to medium-contaminated matrices, e.g. soils, sediments, tailings, solid wastes and waters. For further development, social and commercial acceptance, there is a clear requirement for up-to-date information on successes and failures of these technologies based on evidence from the field. This review reports the outcomes from several integrated experimental attempts to address this at both field and market level in the 29 countries participating in COST Action 859. Results and discussion : This review offers insight into the deployment of promising and emergent in situ phytotechnologies, for sustainable remediation and management of contaminated soils and water, that integrative research findings produced between 2004 and 2009 by members of COST Action 859. Many phytotechnologies are at the demonstration level, but relatively few have been applied in practice on large sites. They are not capable of solving all problems. Those options that may prove successful at market level are (a) phytoextraction of metals, As and Se from marginally contaminated agricultural soils, (b) phytoexclusion and phytostabilisation of metal- and As-contaminated soils, (c) rhizodegradation of organic pollutants and (d) rhizofiltration/rhizodegradation and phytodegradation of organics in constructed wetlands. Each incidence of pollution in an environmental compartment is different and successful sustainable management requires the careful integration of all relevant factors, within the limits set by policy, social acceptance and available finances. Many plant stress factors that are not evident in short-term laboratory experiments can limit the effective deployment of phytotechnologies at field level. The current lack of knowledge on physicochemical and biological mechanisms that underpin phytoremediation, the transfer of contaminants to bioavailable fractions within the matrices, the long-term sustainability and decision support mechanisms are highlighted to identify future R&D priorities that will enable potential end-users to identify particular technologies to meet both statutory and financial requirements. Conclusions : Multidisciplinary research teams and a meaningful partnership between stakeholders are primary requirements that determine long-term ecological, ecotoxicological, social and financial sustainability of phytotechnologies and to demonstrate their efficiency for the solution of large-scale pollution problems. The gap between research and development for the use of phytoremediation options at field level is partly due to a lack of awareness by regulators and problem owners, a lack of expertise and knowledge by service providers and contractors, uncertainties in long-term effectiveness and difficulties in the transfer of particular metabolic pathways to productive and widely available plants. Networks such as COST Action 859 are highly relevant to the integration of research activity, maintenance of projects that demonstrate phytoremediation at a practical field scale and to inform potential end-users on the most suitable techniques. Biomass for energy and other financial returns, biodiversity and ecological consequences, genetic isolation and transfer of plant traits, management of plant-microorganism consortia in terrestrial systems and constructed wetlands, carbon sequestration and soil and water multi-functionality are identified as key areas that need to be incorporated into existing phytotechnologies.

An international two-stage genome-wide search for schizophrenia susceptibility genes.

Abstract: Schizophrenia is thought to be a multifactorial disease with complex mode of inheritance. Using a two-stage strategy for another complex disorder, a number of putative IDDM-susceptibility genes have recently been mapped. We now report the results of a two-stage genome-wide search for genes conferring susceptibility to schizophrenia. In stage I, model-free linkage analyses of large pedigrees from Iceland, a geographical isolate, revealed 26 loci suggestive of linkage. In stage II, ten of these were followed-up in a second international collaborative study comprising families from Austria, Canada, Germany, Italy, Scotland, Sweden, Taiwan and the United States. Potential linkage findings of stage I on chromosomes 6p, 9 and 20 were observed again in the second sample. Furthermore, in a third sample from China, fine mapping of the 6p region by association studies also showed evidence for linkage or linkage disequilibrium. Combining our results with other recent findings revealed significant evidence for linkage to an area distal of the HLA region on chromosome 6p. However, in a fourth sample from Europe, the 6p fine mapping finding observed in the Chinese sample could not be replicated. Finally, evidence suggestive of locus heterogeneity and oligogenic transmission in schizophrenia was obtained.

Survival with Olaparib in Metastatic Castration-Resistant Prostate Cancer.

Abstract: Background We previously reported that olaparib led to significantly longer imaging-based progression-free survival than the physician’s choice of enzalutamide or abiraterone among men wit...

SR-Tesseler: a method to segment and quantify localization-based super-resolution microscopy data

Abstract: Localization-based super-resolution techniques open the door to unprecedented analysis of molecular organization. This task often involves complex image processing adapted to the specific topology and quality of the image to be analyzed. Here we present a segmentation framework based on Voronoi tessellation constructed from the coordinates of localized molecules, implemented in freely available and open-source SR-Tesseler software. This method allows precise, robust and automatic quantification of protein organization at different scales, from the cellular level down to clusters of a few fluorescent markers. We validated our method on simulated data and on various biological experimental data of proteins labeled with genetically encoded fluorescent proteins or organic fluorophores. In addition to providing insight into complex protein organization, this polygon-based method should serve as a reference for the development of new types of quantifications, as well as for the optimization of existing ones.