Diagnosing Latent Tuberculosis Infection in the HIV Era

Tuberculin skin testing (TST) and Interferon-gamma (IFNγ)release assays (IGRAs) are presently the only available assays for the detection of Mycobacterium tuberculosis infected individuals. IGRAs might progressively replace TST, as numerous published reports establish their higher specificity and similar sensitivity when tested in BCG vaccinated, immunocompetent individuals or in populations who may have been in contact with atypical mycobacteria. However, few published reports have commented on their role in TB diagnosis in immunocompromised individuals (HIV, immunosuppressive therapy, cancer…). It is the purpose of this report to review IGRAs published studies in HIV individuals in endemic and non endemic area for tuberculosis (TB). IGRAs were tested in the presence or absence of active TB but correlated to duration of exposure. In newly diagnosed active TB, IGRAs demonstrated a similar sensitivity to TST. In TB non infected individuals, TST and IGRAs also gave similar values when categorization of individuals was correlated to the risk of infection. A higher number of positive IGRAs was observed in individuals from TB endemic areas, in similar proportions to immunocompetent individuals. Comparison between the two IGRAs: QuantiFERON-TB Gold® (QF-TB, Cellestis, Australia) and T-SPOT-TB® (Oxford Immunotec, UK), and against TST, in the same HIV population demonstrates a higher sensitivity of T-SPOT-TB and TST than QF-TB. Indeterminate results, which correspond to the absence of a positive T-cell IFNγ response towards phytohemaglutinin (PHA), is a key point when comparing both IGRAs. This PHA control is indicative of the level of immunosuppression observed in the tested individual. QF-TB seems to present, in HIV populations, more indeterminate results than T-SPOT-TB. The calibration and/or concentration of PBMC on nitrocellulose membrane for the T-SPOT-TB, as compared to a whole blood assay, might explain this difference, with less indeterminate results with the T-SPOT-TB assay. Neither assay is able to differentiate active TB from latent TB infection (LTBI). Several laboratories have tried new antigenic epitopes to solve this issue. It is of importance that these studies need to be repeated on a larger scale by others to validate their results. Two blood assays might add information characterising the evolution from LTBI to active TB: either by losing protective immunity, as demonstrated by the whole blood killing assay, or by evaluating the kinetics of the antibodies synthesized against M. tuberculosis specific antigens. In conclusion, longitudinal studies are still needed to validate IGRAs and other assays and to define their respective predictive values

Teaching protocol exchanges over cellular air interface

International audienceThe evolutionary path taken by cellular standards to the current and future standards is incomplete without fully understanding the older standards. The comprehension of the GSM standard, specifically the procedures for protocols exchange over the air interface will help students understand radio resource allocation procedures in GPRS and UMTS, and will ultimately assist future communication engineers to be able to design and solve problems related to these cellular standards. In this paper we describe the novel architecture of our teaching software, developed and programmed in Java. We present all the user interfaces and show how it can be used to assist in teaching, by presenting how the Mobile station and the GSM/GPRS network exchange data frames over the air interface with their associated protocols. Finally the uniqueness of this teaching tool was proved from the stand point of our modular architecture

Enquêtes de victimation et statistiques de police : les difficultés d’une comparaison

En utilisant une série d’enquêtes nationales de victimation et de statistiques policières françaises pour la période 1985-2002, les auteurs analysent les obstacles à surmonter et les difficultés à résoudre pour comparer ces deux sources, d’abord en ce qui concerne plusieurs sortes d’atteintes aux biens, ensuite différentes catégories de violences

An independent determination of Fomalhaut b's orbit and the dynamical effects on the outer dust belt

The nearby star Fomalhaut harbours a cold, moderately eccentric dust belt with a sharp inner edge near 133 au. A low-mass, common proper motion companion (Fom b), was discovered near the inner edge and was identified as a planet candidate that could account for the belt morphology. However, the most recent orbit determination based on four epochs of astrometry over eight years reveals a highly eccentric orbit that appears to cross the belt in the sky plane projection. We perform here a full orbital determination based on the available astrometric data to independently validate the orbit estimates previously presented. Adopting our values for the orbital elements and their associated uncertainties, we then study the dynamical interaction between the planet and the dust ring, to check whether the proposed disk sculpting scenario by Fom b is plausible. We used a dedicated MCMC code to derive the statistical distributions of the orbital elements of Fom b. Then we used symplectic N-body integration to investigate the dynamics of the dust belt, as perturbed by a single planet. Different attempts were made assuming different masses for Fom b. We also performed a semi-analytical study to explain our results. Our results are in good agreement with others regarding the orbit of Fom b. We find that the orbit is highly eccentric, is close to apsidally aligned with the belt, and has a moderate mutual inclination relative to the belt plane of. If coplanar, this orbit crosses the disk. Our dynamical study then reveals that the observed planet could sculpt a transient belt configuration with a similar eccentricity to what is observed, but it would not be simultaneously apsidally aligned with the planet. This transient configuration only occurs a short time after the planet is placed on such an orbit (assuming an initially circular disk), a time that is inversely proportional to the planet's mass, and that is in any case much less than the 440 Myr age of the star. We constrain how long the observed dust belt could have survived with Fom b on its current orbit, as a function of its possible mass. This analysis leads us to conclude that Fom b is likely to have low mass, that it is unlikely to be responsible for the sculpting of the belt, and that it supports the hypothesis of a more massive, less eccentric planet companion Fom c.Comment: 17 pages, 15 figures, accepted for publication in Astronomy \& Astrophysic

193nm immersion lithography studies with a double grating high NA achromatic interferometer

As immersion lithography will be the lithography technique for sub-65nm generation device fabrication, benefits and drawbacks of the introduction of an immersion fluid between the imaging optics and the wafer have to be studied. In this context, it is of high interest to be able to understand the properties of hyper high NA imaging and to do so, to have access to a technique which can mimic an industrial immersion stepper by having the possibility to tune the polarization state and numerical aperture. Interferometric lithography has proven to be a useful method to study projection imaging at high numerical aperture (NA). It has been shown to help addressing several issues of immersion lithography such as polarization state impact on imaging, photoresists material screening as well as preliminary defectivity considerations due to the introduction of water and high index fluid studies [1, 2, 3]. In the frame of this work, a home-built interferometer with immersion lithography capabilities has been fully designed and mounted in our facilities. Specific designs have been made in order to reach NAs as high as 1.4. All issues preventing the printing of high-contrasted lines over a large area, such as laser beam uniformity and vibrations control have been addressed and 40-nm-half-pitch resist lines can be currently printed with water immersion lithography. As a result, the interferometer has been used to screen resist and topcoat candidates for immersion lithography before their introduction in a production environment. An overview of our results is presented, focusing on the topcoat/resist compatibility. Besides, in order to prepare hyper NA lithography, We have implemented a simulation model which can be used to predict the light distribution inside a photolithographic stack. This model enables us to predict the resist image created by the interference of two coherent beams in the photo-resist volume. Simulations of polarization effects at oblique angles will be presented as well as the evaluation of image contrast in both TE and TM polarization. The contrast in TM polarization is dropping with increasing NA. Finally, we validate those predictions by experiments on our interferometer