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Hepatitis C virus genotypes distribution and transmission risk factors in Luxembourg from 1991 to 2006

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World Journal of Gastroenterology 2008年第8期14卷 1237-1243页

作者： francois roman Karin Hawotte Daniel Struck Anne-Marie Ternes Jean-Yves Servais Vic Arendt Patrick Hoffman Robert Hemmer Thérèse Staub Carole Seguin-Devaux Jean-Claude Schmit Retrovirology Laboratory CRP-Santé 84 rue Val fleuri L-1526 Luxembourg Centre Hospitalier de Luxembourg 4 rue Barblé L-1210 Luxembourg Centre Pénitentiaire de Luxembourg UmKuelebierg L-5299 Schrassig Luxembourg Retrovirology Laboratory CRP-Santé 84 rue Val fleuri L-1526 Luxembourg Centre Hospitalier de Luxembourg 4 rue Barblé L-1210 Luxembourg

AIM： To analyze the Hepatitis C virus （HCV） genotype distribution and transmission risk factors in a population of unselected patients in Luxembourg.METHODS： Epidemiological information （gender, age and transmission risks） were collected from 802 patients newly diagnosed for hepatitis C and living in Luxembourg, among whom 228 patients referred from prison. Genotyping using 5＇noncoding （5＇NC） sequencing was performed. We compared categorical data using the Fisher＇s exact F-test and odds ratios （OR） were calculated for evaluating association of HCV genotype and risk factors.RESULTS： The sex ratio was predominantly male （2.2） and individuals aged less than 40 years represented 49.6% of the population. Genotype 1 was predominant （53.4%） followed by genotype 3 （33%）. Among risk factors, intravenous drug usage （IVDU） was the most frequently reported （71.4%） followed by medical-related transmission （17.6%） including haemophilia, transfusion recipients and other nosocomial reasons. Genotype 3 was significantly associated to IVDU （OR = 4.84, P 〈 0.0001） whereas genotype 1 was significantly associated with a medical procedure （OR = 2.42, P 〈 0.001）. The HCV genotype distribution from inmate patients differed significantly from the rest of the population （Chi-square test with four degrees of freedom, P 〈 0.0001） with a higher frequency of genotype 3 （46.5% vs 27.5%） and a lower frequency of genotype 1 and 4 （44.7% vs 56.8% and 5.3% vs 9.6%, respectively）. IVDU was nearly exclusively reported as a risk factor in prison.CONCLUSION： We report the first description of the HCV genotype distribution in Luxembourg. The repartition is similar to other European counties, with one of the highest European prevalence rates of genotype 3 （33%）. Since serology screening became available in 2992, IVDU remains the most common way of HCV transmission in Luxembourg.

关键词： Hepatitis C virus Genotypes Luxembourg Risk factors Substance abuse Prisons

Skin Friction Gage for Measurements in Hypersonic Flow

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Journal of Thermal Science 2003年第1期12卷 44-50页

作者： francois Falempin Marat Goldfeld roman Nestoulia EADS Aerospatiale Matra Missiles ChatillonInstitute of Theoretical and Applied Mechanics NovosibirskInstitute of Theoretical and Applied Mechanics Novosibirsk France Russia Russia

A description and results of tests of a new small-scale gage for direct measurement of skin friction force are presented in the *** gage design provides separated measurement of longitudinal and transversal component of friction *** of this scheme provides high sensitivity and necessary high-frequency response of the *** tests of the gage were carried out in a blow down wind tunnel at Mach numbers of 2 and 4 within the range of Reynolds numbers Rex from 0.8 to 5 million and in the hot-shot wind tunnel at Mach number 6 and Reynolds numbers Rex=2.5-10 *** measurements of skin friction were carried out on a flat plate and on a ramp beyond the shock *** with the direct measurement of friction in the blow down wind tunnel,the measurements of profiles of average velocities and mass flow rate pulsations were *** of measurement errors has shown that the friction gage permits to measure skin friction coefficient on a flat plate with mistake not more than 10%.

关键词： skin friction gage hypersonic flow scramjet.

Inverse Scattering for a Schr■dinger Operator with a Repulsive Potential

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Acta Mathematica Sinica,English Series 2006年第5期22卷 1485-1492页

作者： francois NICOLEAU Laboratoire de Mathéatiques Jean Leray UMR CNRS-UN 6629 Département de Mathématiques2 rue de la Houssinière BP 92208 F-44322 Nantes cedex 03 France

We consider a pair of Hamiltonians （H, H0） on L2（R^n）, where H0=p^2 -x^2 is a SchrSdinger operator with a repulsive potential, and H = H0＋V（x）. We show that, under suitable assumptions on the decay of the elect... 详细信息

关键词： Inverse scattering Repulsive potential

Conditions for Set Agreement with an Application to Synchronous Systems

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Journal of Computer Science & Technology 2009年第3期24卷 418-433页

作者： francois Bonnet Michel Raynal IRISA University of Rennes35042 Rennes CedexFrance

The k-set agreement problem is a generalization of the consensus problem： considering a system made up of n processes where each process proposes a value, each non-faulty process has to decide a value such that a decided value is a proposed value, and no more than k different values are decided. While this problem cannot be solved in an asynchronous system prone to t process crashes when t≥ k, it can always be solved in a synchronous system; [t/k]＋1 is then a lower bound on the number of rounds （consecutive communication steps） for the non-faulty processes to decide. The condition-based approach has been introduced in the consensus context. Its aim was to both circumvent the consensus impossibility in asynchronous systems, and allow for more efficient consensus algorithms in synchronous systems. This paper addresses the condition-based approach in the context of the k-set agreement problem. It has two main contributions. The first is the definition of a framework that allows defining conditions suited to the l-set agreement problem and the second is a generic synchronous k-set agreement algorithm based on conditions.

关键词： agreement problem condition efficiency lower bound synchronous system

Discrete Duality Finite Volume Discretization of the Thermal-P_(N) Radiative Transfer Equations on General Meshes

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Communications in Computational Physics 2022年第2期31卷 398-448页

作者： francois Hermeline Universite Paris-Saclay Laboratoire en Informatique Haute Performance pour le Calcul et la simulationCEADAMDIF91297 ArpajonFrance

The discrete duality finite volume method has proven to be a practical tool for discretizing partial differential equations coming from a wide variety of areas of physics on nearly arbitrary *** main ingredients of the method are:(1)use of three meshes,(2)use of the Gauss-Green theorem for the approximation of derivatives,(3)discrete integration by *** this article we propose to extend this method to the coupled grey thermal-P_(N) radiative transfer equations in Cartesian and cylindrical coordinates in order to be able to deal with two-dimensional Lagrangian approximations of the interaction of matter with *** stability under a Courant-Friedrichs-Lewy condition and the preservation of the diffusion asymptotic limit are proved while the experimental second-order accuracy is observed with manufactured *** numerical experiments are reported which show the good behavior of the method.

关键词： Hybrid multiscale models radiative transfer equation grey P_(N)approximation discrete duality finite volume method

Maximizing the Delivery of MPR Broadcasting Under Realistic Physical Layer Assumptions

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Journal of Computer Science & Technology 2008年第3期23卷 451-460页

作者： francois Ingelrest David Simplot-Ryl LCAV EPFLCH-1015LausanneSwitzerland IRCICA/LIFL CNRS UMR 8022Univ.Lille 1INRIA Lille-Nord EuropeFrance

It is now commonly accepted that the unit disk graph used to model the physical layer in wireless networks does not reflect real radio transmissions, and that a more realistic model should be considered for experimental simulations. Previous work on realistic scenarios has been focused on unicast, however broadcast requirements are fundamentally different and cannot be derived from the unicast case. Therefore, the broadcast protocols must be adapted in order to still be efficient under realistic assumptions. In this paper, we study the well-known multipoint relay broadcast protocol （MPR）, in which each node has to choose a set of 1-hop neighbors to act as relays in order to cover the whole 2-hop neighborhood. We give experimental results showing that the original strategy used to select these multipoint relays does not suit a realistic model. On the basis of these results, we propose new selection strategies solely based on link quality. One of the key aspects of our solutions is that our strategies do not require any additional hardware and may be implemented at the application layer, which is particularly relevant to the context of ad hoc and sensor networks where energy savings are mandatory. We finally provide new experimental results that demonstrate the superiority of our strategies under realistic physical assumptions.

关键词： ad hoc network multipoint relay broadcasting realistic physical layer sensor network

The Micromechanics of Biological and Biomimetic Staggered Composites

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Journal of Bionic Engineering 2012年第4期9卷 446-456页

作者： Sacheen Bekah Reza Rabiei francois Barthelat Department of Mechanical Engineering McGill University 817 Sherbrooke Street West Montreal QC H3A 2K6 Canada

Natural materials such as bone, tooth and nacre achieve attractive properties through the ＂staggered structure＂, which consists of stiff, parallel inclusions of large aspect ratio bonded together by a more ductile and tougher matrix. This seemingly simple structure displays sophisticated micromechanics which lead to unique combinations of stiffness, strength and toughness. In this article we modeled the staggered structure using finite elements and small Representative Volume Elements （RVEs） in order to explore microstructure-property relationships. Larger aspect ratio of inclusions results in greater stiffiless and strength, and also significant amounts of energy dissipation provided the inclusions do not fracture in a brittle fashion. Interestingly the ends of the inclusions （the junctions） behave as crack-like features, generating theoretically infinite stresses in the adjacent inclusions. A fracture mechanics criterion was therefore used to predict the failure of the inclusions, which led to new insights into how the interfaces act as a ＂＇soft wrap＂ for the inclusions, completely shielding them from excessive stresses. The effect of statistics on the mechanics of the staggered structure was also assessed using larger scale RVEs. Variations in the microstructure did not change the modulus of the material, but slightly decreased the strength and significantly decreased the failure strain. This is explained by strain localization, which can in turn be delayed by incorporating waviness to the inclusions. In addition, we show that the columnar and random arrangements, displaying different deformation mechanisms, lead to similar overall prop- erties. The guidelines presented in this study can be used to optimize the design of staggered synthetic composites to achieve mechanical performances comparable to natural materials.

关键词： biological materials biomimetics representative volume element fracture mechanics finite element analysis

Multiscale Mechanics and Optimization of Gastropod Shells

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Journal of Bionic Engineering 2011年第4期8卷 357-368页

作者： Mostafa Yourdkhani Damiano Pasini francois Barthelat Department of Mechanical Engineering McGill University 817 Sherbrooke Street West Montreal QC H3A 2K6 Canada

A vast majority of mollusks grow a hard shell for protection. The structure of these shells comprises several levels of hierarchy that increase their strength and their resistance to natural threats. This article focuses on nacreous shells, which are composed of two distinct layers. The outer layer is made of calcite, which is a hard but brittle material, and the inner layer is made of nacre, a tough and ductile material. The inner and outer layers are therefore made of materials with distinct structures and properties. In this article, we demonstrate that this system is optimum to defeat attacks from predators. A two-scale mod- eling and optimization approach was used. At the macroscale, a two-layer finite element model of a seashell was developed to capture shell geometry. At the microscale, a representative volume element of the microstructure of nacre was used to model the elastic modulus of nacre as well as a multiaxial failure criterion, both expressed as function of microstructural parameters. Experiments were also performed on actual shells of red abalone to validate the results obtained from simulations and gain insight into the way the shell fails under sharp perforation. Both optimization and experimental results revealed that the shell displays optimum performance when two modes of failure coincide within the structure. Finally, guidelines for designing two-layer shells were proposed to improve the performance of engineered protective systems undergoing similar structural and loading conditions.

关键词： seashell multiscale modeling representative volume element failure criterion nacre multiscale optimization

Development of a portable reference aerosol generator （PRAG） for calibration of particle mass concentration measurements

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Particuology 2018年第2期16卷 134-142页

作者： francois Gaie-Levrel Soleiman Bourrous Tatiana Macé Laboratoire national de metrologie et d'essais (LNE) Chemistry and Biology Division Gas and Aerosol Metrology Department I Rue Caston Boissier 75724 Paris Cedex 15 France Institut de Radioprotection et de SUreté Nucleaire (LRSN) PSNRES SCA Gif-sur-Yvette 91192 France

The tapered element oscillating microbalance with filter dynamics measurement system （TEOM-FDMS） is an instrument commonly employed by the French air quality monitoring network. This instrument is currently calibrated with calibration weights traceable to SI but having value and mass differences between each of them that are not representative of real atmospheric particle mass measurements. Moreover, these calibration weights do not allow detection of any technical problems associated with either the TEOM-FDMS sampling system upstream of the mass measurement or the intrinsic TEOM-FDMS filtration system. Therefore, a calibration method was developed using a portable reference aerosol generator （PRAG） that produces known and stable particle mass concentrations over time. Here, we present the characterization of the PRAG system in terms of a reference range of particle masses between 30 - 10 and 3456 ± 83 μg at three sampling times. Its coupling with the TEOM-FDMS and a global comparison between the defined reference range of particle masses and the measured masses obtained with each TEOM-FDMS implicated in this study are also presented.

关键词： Aerosol Generator Mass concentration Particulate mass Calibration TEOM-FDMS