Catalogue des habitats forestiers de Guyane

Grâce à de nombreux efforts de prospections et d'inventaires naturalistes, la biodiversité guyanaise est de mieux en mieux connue et les listes d'espèces nouvelles ne cessent de s'allonger années après années. Cependant l'écosystème forestier ne se résume pas à une juxtaposition d'individus et d'espèces : de complexes relations interspécifiques régissent le fonctionnement des communautés qui sont elles-mêmes influencées par les conditions environnementales. dans lesquelles elles se développent. Gérer et conserver la biodiversité guyanaise implique de mieux cerner ces interactions entre faune, flore et environnement ; interactions qui façonnent toute une diversité d'habitats forestiers avec des dynamiques propres et des compositions originales. Plusieurs programmes de recherche se sont attelés à démêler cet écheveau écologique en se concentrant tout d'abord sur quelques plateformes scientifiques (Paracou, Nouragues, Piste de Saint-Elie) puis en élargissant la focale à l'ensemble de notre territoire sous l'impulsion des gestionnaires publics et des associations naturalistes guyanaises (programmes de recherche DIME, ECOTROP, HABITATS, etc.). Ce catalogue des habitats forestiers présente une synthèse de ces résultats sous la forme de fiches descriptives dressant un portrait précis des différents habitats naturels rencontrés en forêt guyanaise et des mécanismes qui les ont peu à peu façonnés. Un travail collectif important a été accompli pour fournir des éléments précis concernant les cortèges de grande faune, les peuplements d'arbres qui les abritent et la qualité des sols qui les supportent

Jamming coverage in competitive random sequential adsorption of binary mixture

We propose a generalized car parking problem where cars of two different sizes are sequentially parked on a line with a given probability $q$. The free parameter $q$ interpolates between the classical car parking problem of only one car size and the competitive random sequential adsorption (CRSA) of a binary mixture. We give an exact solution to the CRSA rate equations and find that the final coverage, the jamming limit, of the line is always larger for a binary mixture than for the uni-sized case. The analytical results are in good agreement with our direct numerical simulations of the problem.Comment: 4 pages 2-column RevTeX, Four figures, (there was an error in the previous version. We replaced it (including figures) with corrected and improved version that lead to new results and conclusions

Incidence of Hypertension in a Cohort of Spanish University Graduates:The SUN Study

Hypertension is a major public health problem. However, no estimates of age- and sex-specific incidences are available for the Spanish population. Our objective was to estimate the incidence of hypertension in a cohort of university graduates in Spain. We followed up 5648 individuals aged 25-65 years who were initially free of hypertension, diabetes, and cardiovascular disease for a median of 30 months. New diagnoses of hypertension were identified using mailed questionnaires. We validated the self-reported diagnosis of hypertension. In 18 250 person-years of follow-up, we identified 248 new cases of hypertension. The unadjusted incidences of hypertension in women and men were 8.2 per 1000 person-years (95% CI, 6.7-10.1) and 21.8 per 1000 person-years (95% CI, 18.6-25.4), respectively. The cumulative probability of receiving a medical diagnosis of hypertension by the age of 65 years was 50% among women and 72% among men. In conclusion, we have provided new evidence confirming that hypertension is one of the most important public health problems in Spain

Kinetic Roughening in Deposition with Suppressed Screening

Models of irreversible surface deposition of k-mers on a linear lattice, with screening suppressed by disallowing overhangs blocking large gaps, are studied by extensive Monte Carlo simulations of the temporal and size dependence of the growing interface width. Despite earlier finding that for such models the deposit density tends to increase away from the substrate, our numerical results place them clearly within the standard KPZ universality class.Comment: nine pages, plain TeX (4 figures not included

Kinetics and Jamming Coverage in a Random Sequential Adsorption of Polymer Chains

Using a highly efficient Monte Carlo algorithm, we are able to study the growth of coverage in a random sequential adsorption (RSA) of self-avoiding walk (SAW) chains for up to 10^{12} time steps on a square lattice. For the first time, the true jamming coverage (theta_J) is found to decay with the chain length (N) with a power-law theta_J propto N^{-0.1}. The growth of the coverage to its jamming limit can be described by a power-law, theta(t) approx theta_J -c/t^y with an effective exponent y which depends on the chain length, i.e., y = 0.50 for N=4 to y = 0.07 for N=30 with y -> 0 in the asymptotic limit N -> infinity.Comment: RevTeX, 5 pages inclduing figure

Feasibility of Electrified Propulsion for Ultra-Efficient Commercial Aircraft Final Report

MIT, Aurora Flight Sciences, and USC have collaborated to assess the feasibility of electric, hybridelectric, and turbo-electric propulsion for ultra-efficient commercial transportation. The work has drawn on the team expertise in disciplines related to aircraft design, propulsion-airframe integration, electric machines and systems, engineering system design, and optimization. A parametric trade space analysis has been carried out to assess vehicle performance across a range of transport missions and propulsion architectures to establish how electrified propulsion systems scale. An optimization approach to vehicle conceptual design modeling was taken to enable rapid multidisciplinary design space exploration and sensitivity analysis. The results of the analysis indicate vehicle aero-propulsive integration benefits enabled by electrification are required to offset the increased weight and loss associated with the electric system and achieve enhanced performance; the report describes the conceptual configurations than can offer such enhancements. The main contribution of the present work is the definition of electric vehicle design attributes for potential efficiency improvements at different scales. Based on these results, key areas for future research are identified, and extensions to the trade space analysis suitable for higher fidelity electrified commercial aircraft design and analysis have been developed

Scientific Assessment in Support of the Materials Roadmap Enabling Low Carbon Energy Technologies: Bioenergy

This scientific assessment serves as the basis for a materials research roadmap for bioenergy technology, itself an integral element of an overall "Materials Roadmap Enabling Low Carbon Technologies", a Commission Staff Working Document published in December 2011. The Materials Roadmap aims at contributing to strategic decisions on materials research funding at European and Member State levels and is aligned with the priorities of the Strategic Energy Technology Plan (SET-Plan). It is intended to serve as a guide for developing specific research and development activities in the field of materials for energy applications over the next 10 years. This report provides an in-depth analysis of the state-of-the-art and future challenges for energy technology-related materials and the needs for research activities to support the development of bioenergy technology both for the 2020 and the 2050 market horizons. It has been produced by independent and renowned European materials scientists and energy technology experts, drawn from academia, research institutes and industry, under the coordination the SET-Plan Information System (SETIS), which is managed by the Joint Research Centre (JRC) of the European Commission. The contents were presented and discussed at a dedicated hearing in which a wide pool of stakeholders participated, including representatives of the relevant technology platforms, industry associations and the Joint Programmes of the European Energy Research Associations.JRC.F.2-Cleaner energ

Apparent digestibility and metabolizable energy content of lipid sources in poultry

A trial was conducted to determine the apparent digestibility (ATTD) and AME content of different lipid sources in 21d-old broilers. There were a control diet based on corn and soybean meal without any supplemental fat and 6 additional diets forming a 3x2 factorial with 3 sources of fat (soy oil, SBO; reconstituted monoglyceride oil, RMG; and reconstituted triglyceride oil, RTG) included in the diet (3 or 6%) at expenses (wt:wt) of the basal diet

High Energy Cosmic Rays from Neutrinos

We discuss recent models in which neutrinos, which are assumed to have mass in the eV range, originate the highest energy cosmic rays by interaction with the enhanced density in the galactic halo of the relic cosmic neutrino background. We make an analytical calculation of the required neutrino fluxes to show that the parameter space for these models is constrained by horizontal air shower searches and by the total number of background neutrinos, so that only models which have fairly unnatural halo sizes and enhanced densities are allowed.Comment: 14 pages, 3 ps figures. To appear in Phys. Rev.

Low-fat dairy consumption and reduced risk of hypertension: the Seguimiento Universidad de Navarra (SUN) cohort

BACKGROUND: Some observational studies have shown a beneficial effect of dairy consumption on blood pressure, especially in overweight and relatively young (<40 y) persons. However, no results from prospective studies conducted in a free-living population exist that show this association in middle-aged adults. OBJECTIVE: The aim of the present study was to assess whether total, low-fat, and whole-fat dairy consumption was associated prospectively with the risk of hypertension. DESIGN: This was a prospective study conducted in 5880 university graduates in Spain, aged >20 y in 2000 (mean age: 37 y), free of hypertension and cardiovascular disease at baseline, and followed-up with mailed questionnaires for a median of 27 mo. Dairy consumption was assessed with a previously validated semiquantitative food-frequency questionnaire. RESULTS: One hundred eighty new cases of hypertension were identified. The hazard ratio of hypertension between extreme quintiles of low-fat dairy product consumption was 0.46 (95% CI: 0.26, 0.84; P for trend = 0.02) after adjustment for the main known risk factors for hypertension and several dietary factors. No significant association between whole-fat dairy products or total calcium intake and incident hypertension was seen. CONCLUSION: In this Mediterranean cohort, low-fat dairy consumption, but not whole-fat dairy consumption, was associated with a lower risk of incident hypertension