Numerical Evaluation of the Effective Elastic Properties of 2D Overlapping Random Fibre Composites

We present a numerical investigation of the elastic coefficients of random fibre composites with high contrast of properties. Here we consider a numerical study based on the generation of representative volume elements (RVEs) with overlapping random fibre network. Such a concept requires an important Monte-Carlo draw of patterns as well as an accurate determination of RVE size. In this paper, this latter is done by estimating the evolution of the standard deviation according to the number of realizations for given values of RVE size. We consider the use of an appropriate model for an automatic, reliable and fast generation of RVEs : the model with an n-order approximate geometry that allows the construction of complex overlapping fibre network. It is well-established that the morphology of the microstructure greatly affects the mechanical response of such kind material. Some morphological features, namely orientation, aspect ratio and dispersion are investigated by considering them as random variables in the design of RVEs. The results are subsequently linked to the percolation phenomenon that occurs when fibres overlap and form some pathways inside the soft phase. This phenomenon influences effective properties of heterogeneous media, particularly in the case of a high contrast of properties

Asynchronism in a joint algorithm architecture perspective

Even if the design of asynchronous circuits reaches a certain level of maturity, they are still considered as a curiosity . However, some interesting industrial applications have been developed recently by Philips for pagers and by Sharp-Mitsubishi for set-top boxes . In this paper, the operating mode of asynchronous circuits is first presented, and compared with its synchronous counter-part . The properties and potentials of asynchronous circuits are then described as an introduction to the last part of the paper which aims at showing that the asynchronous operating mode associated with a description formalism based on communicating processes is a powerful tool to jointly design algorithms and architectures .Bien que leurs techniques de conception gagnent en maturité avec notamment l'apparition d'outils automatiques, et que le nombre des réalisations augmente, les circuits asynchrones constituent aujourd'hui encore une curiosité. Toutefois, Philips dans les pagers et Sharp-Mitsubishi dans les Set Top Box sont les premiers à intégrer des circuits asynchrones dans des équipements pré-industriels. Cet article présente dans un premier temps le principe de fonctionnement des circuits asynchrones en le situant par rapport à celui des systèmes synchrones. Les propriétés et potentiels généraux ainsi que les coûts d'implémentation inhérents à ce type de réalisation sont ensuite abordés. Ces deux premières parties introductives constituent les bases du dernier chapitre de l'article qui s'attache à montrer que la combinaison du mode de fonctionnement asynchrone et d'un formalisme de description basé sur les processus séquentiels communicants constitue un outil puissant pour l'étude et la conception conjointe des algorithmes et des architectures. Nous introduisons en particulier la notion de convergence algorithme-architecture qui traduit l'idée qu'algorithme et architecture peuvent être confondus en un seul modèle, décrit sous la forme d'un programme unique qui rend compte à la fois des propriétés fonctionnelles et structurelles de la spécification

Labeling of Multiple HIV-1 Proteins with the Biarsenical-Tetracysteine System

Due to its small size and versatility, the biarsenical-tetracysteine system is an attractive way to label viral proteins for live cell imaging. This study describes the genetic labeling of the human immunodeficiency virus type 1 (HIV-1) structural proteins (matrix, capsid and nucleocapsid), enzymes (protease, reverse transcriptase, RNAse H and integrase) and envelope glycoprotein 120 with a tetracysteine tag in the context of a full-length virus. We measure the impact of these modifications on the natural virus infection and, most importantly, present the first infectious HIV-1 construct containing a fluorescently-labeled nucleocapsid protein. Furthermore, due to the high background levels normally associated with the labeling of tetracysteine-tagged proteins we have also optimized a metabolic labeling system that produces infectious virus containing the natural envelope glycoproteins and specifically labeled tetracysteine-tagged proteins that can easily be detected after virus infection of T-lymphocytes. This approach can be adapted to other viral systems for the visualization of the interplay between virus and host cell during infection

Regolith science with the cameras on the MMX Rover

The JAXA Martian Moons Exploration (MMX) mission [1] has a primary objective to study the formation and origins of Phobos and Deimos. The MMX spacecraft will also deploy a CNES/DLR rover to the surface of Phobos [2,3]. This rover will be the first of its kind to attempt wheeled-locomotion on a low gravity surface. As such, this rover provides a unique opportunity to study not only the surface properties of Phobos, but also regolith dynamics on small-bodies. This information is valuable for understanding the surface processes and geological history of Phobos in addition to being of high importance to the landing (and sampling) operations of the main MMX spacecraft [1]

Low Clinical Burden of 2009 Pandemic Influenza A (H1N1) Infection during Pregnancy on the Island of La Réunion

BACKGROUND: Pregnant women have been identified as a group at risk, both for respiratory complications than for the admissions to the Intensive Care Unit (ICU) during the 2009 H1N1 influenza pandemic (pdm). The purpose of this prospective register-based cohort-study was to characterize the clinical virulence of the pdm (H1N1/09)v during pregnancy in La Réunion. METHODS/PRINCIPAL FINDINGS: Over a twelve-week pdm wave (13 July to 3 October 2009), 294 pregnant women presented with an influenza-like illness (ILI) to one of the three maternity departments of the South Reunion area, Indian Ocean. Out of these, 278 were checked by RT-PCR for influenza viruses (157 positive and 121 negative, of whom, 141 with pdm flu and 132 with ILIs of non pdm origin, 5 untyped). The median body temperature was higher in women experiencing pdm flu than in those with non pdm ILI (38.9 degrees C versus 38.3 degrees C, P<0.0001), without evidence linked to circulating viremia. Oseltamivir was given for 86% of pdm flu cases in a median time inferior than 48 hrs (range 0-7 days). The hospitalization rate for pdm flu was of 60% and not associated with underlying conditions. Six viral pneumonia and fourteen asthma attacks were observed among 84 hospitalized pdm flu cases, of whom, only one led to the ICU for an acute lung injury. No maternal death occurred during the pdm wave. None adverse pregnancy outcome was associated with pdm flu. No congenital birth defect, nor early-onset neonatal influenza infection was attributable to pdm flu exposure. CONCLUSIONS/SIGNIFICANCE: This report mitigates substantially the presumed severity of pandemic H1N1/09 influenza infection during pregnancy. The reasons for which the clinical burden of H1N1/09 influenza virus may differ worldwide raise questions about a differential local viral-strain effect and public health preparedness, notably in timely access to special care and antiviral treatments

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Métamagnétisme d'un antiferromagnétique fortement anisotrope

It is shown that the range of magnetic interactions deeply influences the metamagnetism of the Ising antiferromagnet. In the case of dysprosium aluminium garnet, the values of the threshold fields at which a bulk magnetization of the sample appears are derived semi-empirically for both directions of the applied magnetic field in which the phenomenon has been studied. The thermal behaviour is briefly discussed.On montre l'influence de la portée des interactions magnétiques sur le métamagnétisme d'un antiferromagnétique d'Ising. Par une méthode semi-empirique, on calcule dans le cas du grenat d'aluminium et de dysprosium les valeurs des champs seuils à 0 °K où une aimantation globale du spécimen apparaît pour les deux directions du champ magnétique appliqué dans lesquelles le phénomène a été étudié. On donne une brève interprétation du comportement en fonction de la température