A Stochastic Model of Latently Infected Cell Reactivation and Viral Blip Generation in Treated HIV Patients

Motivated by viral persistence in HIV+ patients on long-term anti-retroviral treatment (ART), we present a stochastic model of HIV viral dynamics in the blood stream. We consider the hypothesis that the residual viremia in patients on ART can be explained principally by the activation of cells latently infected by HIV before the initiation of ART and that viral blips (clinically-observed short periods of detectable viral load) represent large deviations from the mean. We model the system as a continuous-time, multi-type branching process. Deriving equations for the probability generating function we use a novel numerical approach to extract the probability distributions for latent reservoir sizes and viral loads. We find that latent reservoir extinction-time distributions underscore the importance of considering reservoir dynamics beyond simply the half-life. We calculate blip amplitudes and frequencies by computing complete viral load probability distributions, and study the duration of viral blips via direct numerical simulation. We find that our model qualitatively reproduces short small-amplitude blips detected in clinical studies of treated HIV infection. Stochastic models of this type provide insight into treatment-outcome variability that cannot be found from deterministic models

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Why is Iridium the best substrate for single crystal diamond growth?

The synthesis of heteroepitaxial monocrystalline diamond films has been of technological and scientific interest for several decades. Using chemical vapor deposition techniques, polycrystalline diamond has been successfully grown on many substrates. However, iridium emerges in providing highly oriented films, significantly better than any other transition metals. In the present work we propose an ab initio density functional study of the interaction of diamond with different substrates used experimentally. The origin of iridium's specific behavior is investigated. The kinetics of carbon atoms in the substrate lattice is found to play a key role, determining the nucleation mechanisms and hence the quality of the final diamond film. (c) 2005 American Institute of Physics

Reactive gas pulsing process: a method to extend the composition range of sputtered iron oxynitride films

International audienc

Structural properties of iron oxynitride films obtained by reactive magnetron sputtering

International audienc

Caractérisation des films colorés de Fe-O-N élaborés par pulvérisation magnétron réactive

International audienc

Influence of Oxygen Flow Rate on the Properties of FeOXNY Films Obtained by Magnetron Sputtering at High Nitrogen Pressure

International audienceFe-O-N films were successfully deposited by magnetron sputtering of an iron target in Ar-N2-O2 reactive mixtures at high nitrogen partial pressure 1.11 Pa (Q(N2) = 8 sccm) using a constant flow rate of argon and an oxygen flow rate Q(O2) varying from 0 to 1.6 sccm. The chemical composition and the structural and microstructural nature of these films were characterized using Rutherford Backscattering Spectrometry, X-ray diffraction, and Conversion Electron Mössbauer Spectrometry, respectively. The results showed that the films deposited without oxygen are composed of a single phase of γ''-FeN, whereas the other films do not consist of pure oxides but oxidelike oxynitrides. With higher oxygen content, the films are well-crystallized in the α-Fe2O3 structure. At intermediate oxygen flow rate, the films are rather poorly crystallized and can be described as a mixture of oxide γ-Fe2O3/Fe3O4. In addition, the electrical behavior of the films evolved from a metallic one to a semiconductor one, which is in total agreement with other investigations. Comparatively to a previous study carried out at low nitrogen partial pressure (0.25 Pa), this behavior of films prepared at higher nitrogen partial pressure (1.11 Pa) could be caused by a catalytic effect of nitrogen on the crystallization of the hematite structure

Reconstitutions paléoenvironnementales et enregistrement paléoclimatique fini-carbonifère à permien du bassin d’Autun (Nord-Est du Massif Central)

International audienceLes bassins sédimentaires tardi-orogéniques fini-carbonifères à permiens du Nord-Est du Massif Central (bassins d’Autun, de l’Aumance, de Decize-La Machine et de Blanzy-Le Creusot) ont été principalement étudiés pour leur potentiel en ressources carbonées jusque dans les années 1980. Le regain d’intérêt qu’ils suscitent aujourd’hui s’appuie sur des aspects plus fondamentaux afin de mieux comprendre la période charnière qu’est la fin du Paléozoïque. Les séries sédimentaires préservées dans ces bassins continentaux enregistrent en effet le démantèlement des reliefs hercyniens ainsi que l’évolution climatique (transition icehouse-greenhouse) se produisant entre la fin de l’accrétion de la Pangée et le début de sa dislocation, amorcée au Mésozoïque. Pour mener à bien les reconstitutions paléoenvironnementales et paléoclimatiques de cette période, une étude multidisciplinaire est proposée, couplant des approches sédimentologiques, pétrologiques, géochimiques, structurales et géochronologiques de ces différents bassins, dont le calage stratigraphique est mal contraint. Le bassin d’Autun, comprenant les séries stéphaniennes et autuniennes du Carbonifère terminal au Permien inférieur, a fait l’objet d’une étude sédimentologique basée sur la description des carottes des forages d’Igornay (186 m) et de Chevrey (365 m), respectivement au Nord-Est et à l’Ouest du bassin et traversant la base de la série autunienne. Nos observations permettent de réviser le modèle sédimentologique fluviatile et fluvio-lacustre initialement proposé pour ces séries, en mettant en évidence des faciès essentiellement lacustres (argilites distales carbonées, varves, faciès turbiditiques et deltaïques, microbialites). Les analyses minéralogiques à haute résolution de l’assemblage argileux, complétées par la pyrolyse Rock-Eval et la géochimie isotopique et élémentaire du carbone et de l’azote organiques ont été réalisées sur le forage d’Igornay. Des fluctuations significatives au cours du temps du cycle hydrologique, de l’altération des bassins versants où le volcanisme est omniprésent et de la préservation de la matière organique sont mises en évidence. Ces fluctuations peuvent être reliées aux changements des paléoenvironnements de dépôt (lac proximal vs. lac distal) du bassin ainsi qu’à des évolutions paléoclimatiques de plus grande échelle

Evaluation of the optoelectronic properties of ZnSnN2 thin films under different growth conditions and doping implantation of As and P at different concentrations

National audienc

Evaluation of the optoelectronic properties of ZnSnN2 thin films under different growth conditions and doping implantation of As and P at different concentrations

National audienc