On the background estimation by time slides in a network of gravitational wave detectors

Time shifting the outputs of Gravitational Wave detectors operating in coincidence is a convenient way to estimate the background in a search for short duration signals. However this procedure is limited as increasing indefinitely the number of time shifts does not provide better estimates. We show that the false alarm rate estimation error saturates with the number of time shifts. In particular, for detectors with very different trigger rates this error saturates at a large value. Explicit computations are done for 2 detectors, and for 3 detectors where the detection statistic relies on the logical ``OR'' of the coincidences of the 3 couples in the network.Comment: accepted for publication in CQ

Introduction à la résistance des matériaux

1 - Généralités Concepts généraux Représentation et repère Description lagrangienne 2 - Petites déformations d'un milieu continu Déplacement et transformation Interprétation géométrique de la transformation Déformation autour d'un point Variation d'angle entre deux axes de référence Variation angulaire de deux directions quelconques Dilatation cubique Éléments propres de la matrice des déformations Invariants du tenseur des déformations Conditions d'intégrabilité Représentation de Mohr 3 - Contraintes dans un milieu continu Équilibre d'un domaine solide Notion de contraintes État de contrainte en un point Propriétés de la matrice des contraintes Représentation géométrique des contraintes 4 - Relation de comportement en élastostatique Coefficients élastiques Essai de torsion Critères limites de dimensionnement 5 - Énergie de déformation d'un milieu continu élastique Énergie de déformation Potentiel élastique 6 - Élasticité linéaire Position du problème Résolution Principe de Saint-Venant Applications 7 - Introduction à la théorie des poutres Introduction Problème de Saint-Venant Une théorie approchée des poutres 8 - Treillis Définition Effort normal Contraintes et déformations Équations cinématiques Énergie de déformation Résolution 9 - Théorèmes énergétiques Théorème de réciprocité de Maxwell-Betti Théorème de Castigliano 10 - Flexion des poutres droites Poutre droite et notations générales Équations locales Flexion plane 11 - Assemblages hyperstatiques de poutres Hyperstaticité des systèmes plans Applications Poutre sur appuis dénivelables Méthode des trois moments 12 - Effort tranchant Position du problème Contraintes de cisaillement et effort tranchant dans une section droite Solution approchée et formule de Bredt Centre de cisaillement 13 - Torsion des poutres Centres de torsion et de cisaillement Poutres de section pleine Section pleine admettant un centre de symétrie Poutres de section à paroi mince fermée 14 - Stabilité de l'équilibre des poutres élastiques longues Formulation du problème Modélisation linéaire du flambement Flambement des pièces longues Influence de l'effort tranchant Calcul de la charge critique d'Euler Déversement des poutres en flexion simple Torsion et traction/compression Stabilité des arcs et anneaux A - Problème de Saint-Venant Méthode des déplacements Méthode des contraintes Comparaison des deux méthodes Engineering schoolLa résistance des matériaux, appelée également mécanique des corps déformables, fait appel aux notions d'équilibre de la mécanique statique, aux notions de déplacements étudiées en cinématique et aux propriétés des matériaux, auxquelles on a recours pour évaluer les dimensions de pièces structurales ou d'éléments de machines. L'objet de cet enseignement est l'étude statique des milieux continus déformables

The Bolcana Cu–Au ore deposit (Metaliferi Mountains, Romania): first data on the alteration and related mineralisation

The Bolcana ore deposit (Metaliferi Mountains, western Romania) is a porphyry ore deposit with associated epithermal veins. On the basis of different parageneses, four alteration types were distinguished: potassic, phyllic, argillic and propylitic. The mineralogical and geochemical data and estimated crystallisation temperatures of alteration minerals indicate an evolution of the system from an early period of porphyry type mineralisation (Cu+Au) to a late period of low-sulphidation epithermal mineralisation (Au+ base metal). To cite this article: V. Milu et al., C. R. Geoscience 335 (2003). 2003 Académie des sciences. Published by Éditions scientifiques et médicales Elsevier SAS. All rights reserved. Résumé Le gisement de cuivre–or de Bolcana (monts Métallifères, Roumanie) : premières données sur les altérations et minéralisations associées. Le gisement de Bolcana (monts Métallifères, Roumanie occidentale) est un gisement de type porphyre, associé à des veines épithermales, dans lequel les quatre types d’altération caractéristiques, potassique, phylliteuse, argileuse et propylitique, ont été reconnus à partir des différentes associations minérales rencontrées. Les analyses minéralogiques et géochimiques ainsi que les températures de cristallisation estimées des minéraux d’altération indiquent une évolution du système depuis une période initiale de minéralisation à cuivre–or de type porphyre jusqu’à une minéralisation épithermale à or–métaux de base de type low-sulphidation. Pour citer cet article: V. Milu et al., C. R. Geoscience 335 (2003)

IRES complexity before IFN-alpha treatment and evolution of the viral load at the early stage of treatment in peripheral blood mononuclear cells from chronic hepatitis C patients.

In the proof, we asked to correct the name of one Author, and the adddess; this was acknowledged by the Editor, but was omitted in the final published version!International audienceAt the early stage of treatment, IFN alpha-2a induces inhibition of HCV replication. The viral load reflects mainly the degradation rate of the viruses. However, differences in the behavior of the viral population depend on changes, which occurred in the HCV-IRES genome. In this study, cloning and sequencing strategies permitted the generation of a large number of IRES sequences from the PBMCs of 18 patients (5 women, 13 men) with chronic hepatitis C. The HCV IRES appeared to be highly conserved structurally. However, some variability was found between the different isolates obtained: 467 substitutions with a median of 7 variants/patients. No relationship was observed between pre-treatment IRES complexity and the viral load at the beginning. However, on review of the evolution of viral load in the PBMCs during the first 3 days of IFN alpha-2a treatment, patients could be classified into two groups: Group 1, in which the viral population continued to replicate and Group 2, in which the viral load decreased significantly (P = 0.01727). Positioning of the mutations on the predicted IRES secondary structure showed that the distribution of the mutations and their apparition frequency were different between the two groups. At the early stage of treatment, IFN alpha-2a was efficient in reducing the viral replication in a significant number of patients; mechanisms of response might affect the virus directly. However, pre-treatment genomic variations observed in the 5'NCR of HCV were not a parameter of a later response to antiviral therapy in chronic hepatitis C patients. (244

Reconstruction of source location in a network of gravitational wave interferometric detectors

This paper deals with the reconstruction of the direction of a gravitational wave source using the detection made by a network of interferometric detectors, mainly the LIGO and Virgo detectors. We suppose that an event has been seen in coincidence using a filter applied on the three detector data streams. Using the arrival time (and its associated error) of the gravitational signal in each detector, the direction of the source in the sky is computed using a chi^2 minimization technique. For reasonably large signals (SNR>4.5 in all detectors), the mean angular error between the real location and the reconstructed one is about 1 degree. We also investigate the effect of the network geometry assuming the same angular response for all interferometric detectors. It appears that the reconstruction quality is not uniform over the sky and is degraded when the source approaches the plane defined by the three detectors. Adding at least one other detector to the LIGO-Virgo network reduces the blind regions and in the case of 6 detectors, a precision less than 1 degree on the source direction can be reached for 99% of the sky.Comment: Accepted in Phys. Rev.

Chauffage par effet plasmon pour la désorption localisée de cellules capturées sur une biopuce

International audienceThis work proposes a miniaturized system able to perform multiple cell capture followed by cell-type selective release from a biochip surface. Unlabeled lymphocytes are first specifically captured onto a DNA array by antibody-DNA conjugates. The immobilized cells are subsequently released under spatio-temporal control within local heating generated by intense Surface Plasmon Resonance (SPR) produced by laser illumination

Features and distribution of CD8 T cells with human leukocyte antigen class I-specific receptor expression in chronic hepatitis C.: NKRs+ CD8 T cells in chronic Hepatitis C.

CD8(+) T cells represent a sizable component of the liver inflammatory infiltrate in chronic hepatitis C and are thought to contribute to immune-mediated tissue injury. Because chronic stimulation may promote the expression by CD8(+) T cells of distinct human leukocyte antigen class I-specific natural killer cell receptors (NKRs) susceptible to both inhibiting effector functions and promoting cell survival, we examined the distribution and characteristics of CD8(+) T cells with such receptors in chronic hepatitis C patients. NKR CD8(+) T cells were detectable in liver and peripheral blood from hepatitis C virus (HCV)-infected patients but were not major subsets. However, the frequency of NKG2A(+) CD8(+) in the liver and in a lesser extent in the peripheral blood was positively correlated to histological activity in HCV-infected patients. No such correlation was found with KIR(+) T cells in liver in HCV-infected patients and with the both NKR CD8(+) T cells in hepatitis B virus (HBV) infected patients. Circulating CD8(+) T cells expressing KIRs exhibited phenotypic features of memory T cells with exacerbated expression of the senescence marker CD57 in patients. NKG2A(+)CD8(+) T cells were committed T cells that appeared less differentiated than KIR(+)CD8(+) T cells. In HCV-infected patients, their content in perforin was low and similar to that observed in NKG2A(-)CD8(+) T cells; this scenario was not observed in healthy subjects and HBV-infected patients. Both NKG2A and KIRs could inhibit the response of HCV-specific CD8(+) T cells ex vivo. CONCLUSION: These results support the concept that an accumulation in the liver parenchyma of NKR(+)CD8(+) T cells that have functional alterations could be responsible for liver lesions. They provide novel insights into the complexity of liver-infiltrating CD8(+) T cells in chronic hepatitis C and reveal that distinct subsets of antigen-experienced CD8(+) T cells are differentially sensitive to the pervasive influence of HCV

La libéralisation des chemins de fer européens au regard de l’histoire

La table ronde « La libéralisation des chemins de fer européens au regard de l’histoire : avancée, risque ou régression ? » avait pour mission de mettre en perspective historique la libéralisation des chemins de fer européens : son évolution et sa place dans une histoire à long terme, ses résultats, les nouvelles relations que ces mesures ont instituées entre gestionnaires des réseaux et exploitants de transport, entre le secteur des transports et les pouvoirs nationaux, régionaux ou locaux. Après une introduction historique assurée par Michèle Merger, chargée de recherche au CNRS, qui rappelle la directive 91/440 et ses quatre recommandations – séparation juridique et comptable de l’infrastructure des réseaux et de leur exploitation, indépendance de gestion des entreprises ferroviaires, leur assainissement financier et le libre accès de nouvelles entreprises exploitantes à l’infrastructure –, qui ont conduit à une évolution très rapide du secteur en quinze ans, quatre questions sont posées aux participants : quels sont les pays et les acteurs européens les plus réfractaires et les plus favorables à cette évolution, et quels sont leurs arguments respectifs ? Existe-t-il une typologie des réformes entreprises, conduisant à des modèles plus u moins largement diffusés ? Quel type de service ferroviaire attendons-nous et pouvons-nous attendre de cette réforme, en d’autres termes, quel est le devenir du concept de service public ferroviaire ? Qu’en est-il de la revitalisation du fret ferroviaire au lendemain de l’ouverture des corridors de fret favorisés par ces directives, quelle est la nouvelle Europe du fret ferroviaire ? Patrice Leroy, directeur honoraire de la SNCF, ancien secrétaire général adjoint du CEEP, président délégué de l’AHICF anime ensuite le débat qui réunit Yves Crozet, professeur à l’université Lumière-Lyon 2, Michel Lebœuf, directeur Développement à Voyageurs France Europe, SNCF, Hubert du Mesnil, président de RFF et Émile Quinet, professeur émérite à l’École nationale des Ponts et Chaussées.ROUND TABLE with Yves CROZET, Michel LEBŒUF, Patrice LEROY, Michèle MERGER, Hubert du MESNIL and Emile QUINET The purpose of the round table discussion of “The liberalization of European railways from a historical perspective: progress, risk, or regression?” was to put the liberalization of European railways into a historical perspective: the discussants’ goal was to define the place and evolution of this trend in an open-ended history, its results, and the new relationships that such measures have brought about between network managers and transportation operators, as well as between the transportation sector and national, regional, and local authorities. After an historical introduction provided by Michèle Merger, a researcher at the CNRS, who reminded us of the 91/440 directive and its four recommendations—the legal and accounting separation of network infrastructures and their operations, the independent management of the railway companies and their financial streamlining, and open access to the infrastructure for new operating companies—led to a very rapid evolution of the sector in fifteen years, the participants were asked four questions: which European countries and players are the most opposed to and the most in favor of this evolution, and what are their respective arguments? Is there a typology of business reform that leads to more or less widespread models? What kind of railway service is in store for us and what should we expect from such reforms? In other words, what is the future of the concept of public railway service? What will be the impact of the revitalization of rail freight in the aftermath of the opening of freight corridors advantaged by these directives? What will the new Europe of rail freight look like? Patrice Leroy, honorary director of the SNCF, former adjunct secretary general of the CEEP, and Deputy Chairman of the AHICF, then moderated the debate that brought together Yves Crozet, professor at the university Lumière-Lyon 2, Michel Leboeuf, developmental director of Voyageurs France Europe, SNCF, Hubert du Mesnil, President of the RFF, and Emile Quinet, professor emeritus at the Ecole nationale des Ponts et Chaussées