Thermal conductivity of InAs quantum dot stacks using AlAs strain compensating layers on InP substrate

International audienceThe growth and thermal conductivity of InAs quantum dot (QD) stacks embedded in GaInAs matrix with AlAs compensating layers deposited on (1 1 3)B InP substrate are presented. The effect of the strain compensating AlAs layer is demonstrated through Atomic Force Microscopy (AFM) and X-ray diffraction structural analysis. The thermal conductivity (2.7 W/m K at 300 K) measured by the 3ω method reveals to be clearly reduced in comparison with a bulk InGaAs layer (5 W/m K). In addition, the thermal conductivity measurements of S doped InP substrates and the SiN insulating layer used in the 3ω method in the 20-200 °C range are also presented. An empirical law is proposed for the S doped InP substrate, which slightly differs from previously presented results

Evolutionary mechanisms of long-term genome diversification associated with niche partitioning in marine picocyanobacteria

Marine picocyanobacteria of the genera Prochlorococcus and Synechococcus are the most abundant photosynthetic organisms on Earth, an ecological success thought to be linked to the differential partitioning of distinct ecotypes into specific ecological niches. However, the underlying processes that governed the diversification of these microorganisms and the appearance of niche-related phenotypic traits are just starting to be elucidated. Here, by comparing 81 genomes, including 34 new Synechococcus, we explored the evolutionary processes that shaped the genomic diversity of picocyanobacteria. Time-calibration of a core-protein tree showed that gene gain/loss occurred at an unexpectedly low rate between the different lineages, with for instance 5.6 genes gained per million years (My) for the major Synechococcus lineage (sub-cluster 5.1), among which only 0.71/My have been fixed in the long term. Gene content comparisons revealed a number of candidates involved in nutrient adaptation, a large proportion of which are located in genomic islands shared between either closely or more distantly related strains, as identified using an original network construction approach. Interestingly, strains representative of the different ecotypes co-occurring in phosphorus-depleted waters (Synechococcus clades III, WPC1, and sub-cluster 5.3) were shown to display different adaptation strategies to this limitation. In contrast, we found few genes potentially involved in adaptation to temperature when comparing cold and warm thermotypes. Indeed, comparison of core protein sequences highlighted variants specific to cold thermotypes, notably involved in carotenoid biosynthesis and the oxidative stress response, revealing that long-term adaptation to thermal niches relies on amino acid substitutions rather than on gene content variation. Altogether, this study not only deciphers the respective roles of gene gains/losses and sequence variation but also uncovers numerous gene candidates likely involved in niche partitioning of two key members of the marine phytoplankton

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Valorisation sur prairie et maïs, de la fertilisation organique et minérale. Etude sur le long terme

National audienc

Modélisation des propriétés thermo-radiatives de composites fibres de carbone/matrice PEEK jusqu'à T = 700 K dans le cadre du procédé de dépose de bande automatisé

International audienc

Plastic ingestion in seabirds of the western Indian Ocean

International audienceWe investigated seabird plastic ingestion in the western Indian Ocean by analyzing the stomach contents of 222 individuals belonging to nine seabird species (including two endangered species endemics to Reunion Island). The most affected species were tropical shearwaters (79%) and Barau's petrels (59%). The average number of plastic particles per contaminated bird was higher in Barau's petrels (6.10 ± 1.29) than in tropical shearwaters (3.84 ± 0.59). All other studied species also showed plastic presence in their stomach contents. The mass of plastic particles was significantly higher both in juvenile's Barau's petrels and tropical shearwaters than in adults. These results demonstrate the foraging areas of seabirds of the western Indian Ocean have a high level of plastic pollution. In Reunion Island, hundreds of tropical shearwaters and Barau's petrels are attracted by urban lights and die each year. We suggest taking advantage of this situation by using these species as long-term indicators of plastic marine pollution in the region

Gene flow homogenises the evolution of arable weed populations at the landscape level

International audienceUm zu bestimmen, ob Unkrautpopulationen, die in benachbarten Feldern wachsen, genetisch voneinander isoliert waren, untersuchten wir die genetische Kontamination der Alopecurus-myosuroides-Populationen in ökologisch bewirtschafteten Feldern durch die Populationen von konventionellen Felder. Die Resistenz gegenüber Herbiziden wurde als ein Maß für den genetischen Fluss in die ökologischen Populationen benutzt, die nicht unter dem selektiven Druck durch Herbizide standen. Die ökologischen Felder enthielten im Durchschnitt 74,5% herbizidresistente Pflanzen (80,1% in den konventionellen Feldern). In benachbarten ökologisch und konventionell bewirtschafteten Feldern wurden identische Resistenzallele gefunden. AFLP-Analysen ließen erkennen, dass die Populationen der ökologisch und konventionell bewirtschafteten Felder eine ähnliche neutrale genetische Diversität besaßen. Der massive Pollenflug von den konventionellen Feldern ist wahrscheinlich kurzfristig für die genetische Zusammensetzung der A. myosuroides Populationen in den biologischen Feldern verantwortlich. Unter Verwendung eines genetischen Demo-Modells sagen wir vorher, dass demografische Zusammenbrüche von Populationen aufgrund einer effektiven Unkrautkontrolle den Genfluss in diese Populationen verstärkt. Felder mit geringen Unkrautdichten könnten als genetische Senken funktionieren und dies würde die Diffusion von Genen aus den benachbarten Populationen mit hohen Unkrautdichten fördern. Die Populationen von allogamen, windbestäubten Arten wie A. myosuroides, die in benachbarten Feldern auftreten, sind damit deutlich keine unabhängigen Einheiten. Die adaptive Evolution und Management dieser Unkräuter sollten deshalb auf einer Skala betrachtet werden, die größer als die eines Feldes ist.To determine whether weed populations growing in neighbouring fields were genetically isolated, we investigated the genetic contamination of Alopecurus myosuroides populations in organic fields by populations in conventional fields. Herbicide resistance was used as a marker for gene flow to organic populations, which are not under herbicide selective pressure. Organic fields contained on average 74.5% herbicide-resistant plants (80.1% in conventional fields). Identical resistance alleles were found in neighbouring organic and conventional fields. AFLP analysis revealed that populations from organic and conventional fields had similar neutral genetic diversity. Massive pollen flow from conventional fields is likely chiefly responsible for the genetic makeup of A. myosuroides populations from organic fields. Using a demo-genetic model, we propose that demographic collapses of populations due to effective weed control enhance gene flow towards these populations. Fields with a low weed density could act as ‘genetic sinks’ that would facilitate the diffusion of genes from neighbouring, dense weed populations. Populations of allogamous wind-pollinated weed species like A. myosuroides occurring in neighbouring fields are therefore clearly not independent units. Adaptive evolution and management of such weeds should thus be considered on a scale broader than the field

Thermoelectric properties of InAs/InP nanostructures

International audienc

High gene flow promotes the genetic homogeneity of arable weed populations at the landscape level

International audienceTo determine whether weed populations growing in neighbouring fields were genetically isolated, we investigated the genetic contamination of Alopecurus myosuroides populations in organic fields by populations in conventional fields. Herbicide resistance was used as a marker for gene flow to organic populations, which are not under herbicide selective pressure. Organic fields contained on average 74.5% herbicide-resistant plants (80.1% in conventional fields). Identical resistance alleles were found in neighbouring organic and conventional fields. AFLP analysis revealed that populations from organic and conventional fields had similar neutral genetic diversity. Massive pollen flow from conventional fields is likely chiefly responsible for the genetic makeup of A. myosuroides populations from organic fields. Using a demo-genetic model, we propose that demographic collapses of populations due to effective weed control enhance gene flow towards these populations. Fields with a low weed density could act as 'genetic sinks' that would facilitate the diffusion of genes from neighbouring, dense weed populations. Populations of allogamous wind-pollinated weed species like A. myosuroides occurring in neighbouring fields are therefore clearly not independent units. Adaptive evolution and management of such weeds should thus be considered on a scale broader than the field

Ambulatory Intravenous Antibiotic Therapy in Quebec: The Hôpital Charles LeMoyne Experience in 1996

From January 1, 1996 to December 31, 1996, 343 patients received outpatient intravenous antibiotic therapy at Charles LeMoyne Hospital, a 436-bed, acute care hospital in Greenfield Park, south of Montréal, Québec. The infectious diseases department saved 2660 bed-days using outpatient therapy. The mean duration of outpatient therapy was 7.76 days; 81.6% of patients were admitted to the program directly from the emergency room, or outpatient hospital clinics or private offices in the community. Hospitalized patients constituted only 18.4% of admissions to the outpatient intravenous antibiotic therapy program. Forty per cent of the surgical/medical staff participated in the program and they were able to generate a significant impact by diverting patients to outpatient therapy. Two types of patients can benefit from an outpatient intravenous antibiotic therapy program. One group of patients needs empirical short term therapy and can be switched to oral sequential therapy after two to five days of outpatient intravenous antibiotic therapy. A second group of patients needs specific long term therapy for the full duration of the antibiotic therapy. Empirical short term therapy can be managed by emergency department or hospital-based primary physicians, or medical/surgical specialists. Specific long term therapy can be managed by microbiology/infectious disease specialists or medical/surgical specialists. Hospitals that want to relieve pressure on emergency rooms and hospital bed demands should create facilities for both types of patients. Cefazolin and gentamicine/tobramycine were the most commonly used antibiotics in empirical short term therapy and in terms of number of patients treated. Ceftriaxone and vancomycin were most commonly used for long term therapy. The Drug acquisition antibiotic cost was $73,117 but constituted only 20antibiotic therapy cost. The per diem ambulatory cost was$140/patient/day