Authentification Distribuée sur Grille de Grappes basée sur LDAP

National audienceEntre les clusters hautes performances et les grilles de PC se dessine une infrastructure intermédiaire constituée de l'interconnexion de clusters : la grille de grappes. Contrairement aux grilles de PC encore dédiées à des applications spécifiques, les grille de grappes doivent, comme les clusters, permettre à plusieurs utilisateurs d'exécuter des applications de natures différentes. Elles imposent également des contraintes supplémentaires car l'extension géographique pose des problèmes de disponibilité et de sécurité. Dans cet article nous nous intéressons à Grid5000, un projet qui se base sur une topologie de type grille de grappes, et plus particulièrement à son système d'authentification. Ce dernier constitue la brique de base qui doit permettre à un utilisateur d'avoir accès aux ressources de l'ensemble de la grille. Nous montrons dans un premier temps les limites des systèmes d'authentification classiques que sont les fichiers locaux et NIS dans une telle configuration. Nous proposons alors une alternative scalable basée sur le protocole LDAP permettant de répondre aux besoins des grilles de grappes, que ce soit en termes de disponibilité, de sécurité ou de performances

Distributed Authentication in GRID5000

International audienceBetween high-performance clusters and grids appears an inter- mediate infrastructure called cluster grid that corresponds to the interconnection of clusters through the Internet. Cluster grids are not only dedicated to specific applications but should allow the users to execute programs of different natures. This kind of architecture also imposes additional constraints as the geographic extension raises availability and security issues. In this context, authentication is one of the key stone by providing access to the resources. Grid5000 is a french project based on a cluster grid topology. This article expounds and justifies the authentication system used in Grid5000. We first show the limits of classical approaches that are local files and NIS in such configurations. We then propose a scalable alternative based on the LDAP protocol allowing to meet the needs of cluster grids, either in terms of availability, security and performances. Finally, among the various applications that can be executed in the Grid5000 platform, we present μgrid, a minimal middleware used for medical data processing

Molding acoustic, electromagnetic and water waves with a single cloak

International audienceWe describe two experiments demonstrating that a cylindrical cloak formerly introduced for linear surface liquid waves works equally well for sound and electromagnetic waves. This structured cloak behaves like an acoustic cloak with an effective anisotropic density and an electromagnetic cloak with an effective anisotropic permittivity, respectively. Measured forward scattering for pressure and magnetic fields are in good agreement and provide first evidence of broadband cloaking. Microwave experiments and 3D electromagnetic wave simulations further confirm reduced forward and backscattering when a rectangular metallic obstacle is surrounded by the structured cloak for cloaking frequencies between 2.6 and 7.0 GHz. This suggests, as supported by 2D finite element simulations, sound waves are cloaked between 3 and 8 KHz and linear surface liquid waves between 5 and 16 Hz. Moreover, microwave experiments show the field is reduced by 10 to 30 dB inside the invisibility region, which suggests the multi-wave cloak could be used as a protection against water, sonic or microwaves

Measuring the subcellular compartmentalization of viral infections by protein complementation assay

International audienceThe recent emergence and reemergence of viruses in the human population has highlighted the need to develop broader panels of therapeutic molecules. High-throughput screening assays opening access to untargeted steps of the viral replication cycle will provide powerful leverage to identify innovative antiviral molecules. We report here the development of an innovative protein complementation assay, termed αCentauri, to measure viral translocation between subcellular compartments. As a proof of concept, the Centauri fragment was either tethered to the nuclear pore complex or sequestered in the nucleus, while the complementary α fragment (<16 amino acids) was attached to the integrase proteins of infectious HIV-1. The translocation of viral ribonucleoproteins from the cytoplasm to the nuclear envelope or to the nucleoplasm efficiently reconstituted superfolder green fluorescent protein or NanoLuc αCentauri reporters. These fluorescence- or bioluminescence-based assays offer a robust readout of specific steps of viral infection in a multiwell format that is compatible for high-throughput screening and is validated by a short hairpin RNA-based prototype screen

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Standardization of Flow Cytometric Immunophenotyping for Hematological Malignancies: The FranceFlow Group Experience.

Flow cytometry is broadly used for the identification, characterization, and monitoring of hematological malignancies. However, the use of clinical flow cytometry is restricted by its lack of reproducibility across multiple centers. Since 2006, the EuroFlow consortium has been developing a standardized procedure detailing the whole process from instrument settings to data analysis. The FranceFlow group was created in 2010 with the intention to educate participating centers in France about the standardized instrument setting protocol (SOP) developed by the EuroFlow consortium and to organise several rounds of quality controls (QCs) in order to evaluate the feasibility of its application and its results. Here, we report the 5 year experience of the FranceFlow group and the results of the seven QCs of 23 instruments, involving up to 19 centers, in France and in Belgium. The FranceFlow group demonstrates that both the distribution and applicability of the SOP have been successful. Intercenter reproducibility was evaluated using both normal and pathological blood samples. Coefficients of variation (CVs) across the centers were <7% for the percentages of cell subsets and <30% for the median fluorescence intensities (MFIs) of the markers tested. Intracenter reproducibility provided similar results with CVs of <3% for the percentages of the majority of cell subsets, and CVs of <20% for the MFI values for the majority of markers. Altogether, the FranceFlow group show that the 19 participating labs might be considered as one unique laboratory with 23 identical flow cytometers able to reproduce identical results. Therefore, SOP significantly improves reproducibility of clinical flow in hematology and opens new avenues by providing a robust companion diagnostic tool for clinical trials in hematology. © 2019 International Society for Advancement of Cytometry