Blazars are the most numerous type of observed high-energy gamma-ray emitters. However, their emission mechanisms and population properties are still not well-understood. Crucial to this understanding are their cosmological redshifts, which are often not easy to obtain. This presents a great challenge to the next-generation ground-based observatory for very-high-energy gamma rays, the Cherenkov Telescope Array (CTA), which aims to detect a large number of distant blazars to study their intrinsic emission properties and to place tight constraints on the extragalactic background light density, amongst others. The successful investigation of these subjects needs a precise redshift determination. Motivated by these challenges, the CTA redshift task force initiated more than 3 years ago a spectroscopic observing program using some of the largest optical and infrared telescopes to measure the redshifts of a large fraction of blazars that are likely to be detected with CTA. In this proceedings, we give an overview of the CTA redshift task force, discuss some of the difficulties associated with measuring the redshifts of blazars and present our sample selection and observing strategies. We end the proceedings with reporting selected results from the program, the on-going collaborative efforts and our plans for the future.

The purpose of the study was to weigh the community burden of chikungunya determinants on Reunion island. Risk factors were investigated within a subset of 2101 adult persons from a population-based cross-sectional serosurvey, using Poisson regression models for dichotomous outcomes. Design-based risk ratios and population attributable fractions (PAF) were generated distinguishing individual and contextual (i.e. that affect individuals collectively) determinants. The disease burden attributable to contextual determinants was twice that of individual determinants (overall PAF value 89.5% vs. 44.1%). In a model regrouping both categories of determinants, the independent risk factors were by decreasing PAF values: an interaction term between the reporting of a chikungunya history in the neighbourhood and individual house (PAF 45.9%), a maximal temperature of the month preceding the infection higher than 28.5 °C (PAF 25.7%), a socio-economically disadvantaged neighbourhood (PAF 19.0%), altitude of dwelling (PAF 13.1%), cumulated rainfalls of the month preceding the infection higher than 65 mm (PAF 12.6%), occupational inactivity (PAF 11.6%), poor knowledge on chikungunya transmission (PAF 7.3%) and obesity/overweight (PAF 5.2%). Taken together, these covariates and their underlying causative factors uncovered 80.8% of chikungunya at population level. Our findings lend support to a major role of contextual risk factors in chikungunya virus outbreaks.

Exposure to animal livestock has been linked to zoonotic transmission, especially of gastrointestinal pathogens. Exposure to animals may contribute to chronic asymptomatic intestinal infection, environmental enteropathy and child under-nutrition in low-income settings. We conducted a cohort study to explore the effect of exposure to cows on growth and endemic diarrhoea in children aged <5 years in a rural, low-income setting in the Indian state of Odisha. The study enrolled 1992 households with 2739 children. Height measurements were available for 824 children. Exposure to cows was measured as (1) the presence of a cowshed within or outside the compound, (2) the number of cows owned by a household, and (3) the number of cowsheds located within 50 m of a household. In a sub-study of 518 households, fly traps were used to count the number of synanthropic flies that may act as vectors for gastrointestinal pathogens. We found no evidence that environmental exposure to cows contributes to growth deficiency in children in rural India, neither directly by affecting growth, nor indirectly by increasing the risk of diarrhoea. We found no strong evidence that the presence of a cowshed increased the number synanthropic flies in households.

La scintillation liquide est une méthode d’analyse de choix du suivi radio toxicologique des travailleurs susceptibles d’être exposés à des sources émettrices β purs. Les éléments étant présents à l’état de traces dans les urines, il est nécessaire d’optimiser la technique de mesure afin d’obtenir la meilleure sensibilité. Ces dernières années ont vu apparaître des nouvelles générations de liquides scintillants, moins polluants et moins toxiques, destinés à remplacer les liquides scintillants traditionnels. Ces scintillants dits de « nouvelle génération » possèdent cependant un inconvénient technique à leur utilisation : une dissipation plus longue de l’énergie émise par le photon de fluorescence résultant de l’interaction entre le milieu scintillant et le rayonnement. Ce phénomène a un impact direct sur la qualité de la détection et amène à rechercher une valeur du Delay Before Burst optimale qui permette de distinguer les signaux du rayonnement de la source à mesurer, de ceux venant du milieu environnant. Cette étude vise à montrer l’importance du choix de la valeur du paramètre Delay Before Burst dans l’optimisation des limites de détection pour les mesures en scintillation liquide. L’influence de ce paramètre a été étudiée sur les différents radionucléides mesurés au Laboratoire d’Analyses Médicales Radiotoxicologiques (LAMR) de l’Institut de Radioprotection et de Sureté Nucléaire (IRSN); le 3H, le 14C et le 89Sr. Notre étude compare les rayonnements β mesurés avec un liquide scintillant traditionnel : le Pico-Fluor 40 et un liquide scintillant de nouvelle génération : l’Ultima Gold LTT.

The atmospheric oxygen reserve is so huge that, in the short term of hundreds or thousands of years, only minor changes can be expected due to fossil fuel burning and deforestation. Each oxygen molecule passes through a living organism, on average, only once in 9000 years. As a consequence, the fastest regulating system must take of the order of hundreds of years. Nevertheless, it is possible that the actual oxygen level is not necessarily at the optimum level for life, but is just an accidental one in the course of the earth's history. Tropical forests are not the ‘lungs’ of the earth in terms of hundreds of years, but only on a much longer time scale, likewise for all other vegetation which produce humus and the long-term fossil carbon. The driving force is related to the slight differences caused by external factors between photosynthesis and respiration, with subsequent organic matter deposition or consumption for short time regulation of hundreds of years; while, for periods of millions of years, the regulation depends on changes of weathering or burial of fossil sedimentary organic matter.

The transition and the development of turbulence in the near wake of a circular cylinder are investigated using hot-wire anemometry and flow visualization. The formation zone of the large regular vortices is studied in the subcritical regime (2000 < U0D/v < 60000). with and without the introduction of a splitter plate. Two different regimes are identified in the interaction between the von Kármán vortices and those of the shear layer emerging from the separated boundary layer. Experimental evidence is given in support of the strong coupling at low Reynolds numbers characterized by phase modulations between the two types of structures. The interaction is weaker at high Reynolds numbers where the small-scale vortices are disconnected from the regular vortex shedding, giving rise to an intermittent pattern. Spectral properties are used to describe the different stages of the interaction between the shear-layer vortices and the alternating ones. Physical properties of the interaction are examined separately in a numerical simulation using a pressure-velocity formulation. Both unexcited and excited two-dimensional plane mixing layers are studied using streakline maps and time traces of the dynamical properties. The main features of the simulated vortex development are in agreement with the experimental results.

En 1998 et 1999, 160 incidents susceptibles d'avoir entraîné une exposition externe ou interne de travailleurs ou de membres du public et ayant fait l'objet de mesures et/ou d'estimations individuelles ont été signalés à l'ex-OPRI, organisme dont une partie a fusionné avec l'Institut de protection et de sûreté nucléaire (IPSN) en 2002 pour former l'IRSN. Cette étude décrit les caractéristiques de ces incidents en termes de lieu de survenue, circonstances de découverte et conséquences prévisibles ou réelles. L'analyse statistique de ces évènements montre une grande diversité des lieux de survenue, les principaux secteurs étant l'industrie nucléaire (57 % des incidents), les laboratoires de recherche (19 %) et le secteur médical (14 %). Au total, 369 personnes ont été concernées par ces 160 incidents et parmi celles-ci, 305 pour des suspicions de contamination, 54 pour celles d'irradiation et enfin 10 pour une suspicion de contamination et d'irradiation concomitantes. Les mesures réalisées ont confirmé la contamination chez la moitié des personnes concernées. En ce qui concerne le risque d'irradiation, sur 64 personnes susceptibles d'avoir été exposées, 34 ont reçu une dose non nulle, supérieure à 50 mSv pour quatre d'entre elles. Compte tenu de la fréquence des incidents de contamination, il serait souhaitable de développer des études spécifiques sur les radionucléides concernés, en particulier ceux utilisés dans les laboratoires de recherche et dans le domaine médical afin d'améliorer l'expertise en cas d'incident dans ces secteurs.

The 677cytosine (c)→thymine(T) mutation identified in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene has been frequently associated with an elevated plasma homocysteine concentration. The aim of the present study was to determine the impact of this MTHFR common mutation on plasma and erythrocyte folate (RCF) and plasma total homocysteine (tHcy) concentrations in healthy French adults. A cohort of 291 subjects living in the Paris area and participating in the Supplementation en Vitamines et Mineraux Antioxydants (SU.VI.MAX) study were analysed to assess the impact of MTHFR polymorphism 677C→T on folate status and plasma tHcy concentration. The frequency of the mutant homozygote for 677C→T polymorphism (677TT genotype) in the present cohort was 16·8%. There were significant differences in plasma tHcy between 677CC, 677CT and 677TT genotype groups. The RCF concentrations were significantly different between each genotype, the lowest levels being associated with the 677TT genotype. When segregated by gender, no differences in tHcy between homozygous 677TT, heterozygous 677CT and wild-type 677CC genotype groups in women were observed. The fasting tHcy in women was unrelated to the 677C→T mutation. However, tHcy was significantly increased in men with the homozygous 677TT genotype. We also analysed the possible implication of a second new MTHFR polymorphism (1298A→C) in subjects with mild hyperhomocysteinaemia (4th quartile of homocysteinaemia; tHcy >11·1 μmol/l). The polymorphism 1298A→C did not have a notable effect on tHcy or on the RCF levels. Our observations confirm a relatively high frequency of the 677TT genotype in the French population. Women with this genotype did not show the same increase in tHcy observed in men. In the present study dietary folate intake was not measured. Thus, the interaction of dietary folate with the MTHFR genotype in the French population needs further study.

We have studied the effect of common mutations (677C → T and 1298A → C) of the methylenetetrahydrofolate reductase (MTHFR) gene in sixty-six healthy French subjects, aged 27–47 years. Serum folate, vitamin B12, and plasma total homocysteine were measured as well as the specific activity of MTHFR in lymphocytes. The frequency of subjects homozygous for the 677TT genotype was 18 %, and that of those homozygous for the 1298CC genotype was 12·5 %. The frequency of individuals heterozygous for both mutations was 23·5 %. The 1298A → C mutation was associated with decreased MTHFR specific activity in subjects with both 677CC and 677CT genotypes. This activity was 60 % for the 677CC/1298AC genotype and 52 % for the 677CC/1298CC genotype when compared with the MTHFR specific activity of the 677CC/1298AA genotype. Heterozygotes for both mutations (677CT/1298AC genotype) had 36 % of the reference specific activity. Although homocysteine levels in 677TT and 1298CC genotype subjects were higher than for other genotypes, no significant differences were observed among different genotypes. This may be due to high serum folate level in our samples, and suggests that folate therapy may be useful to prevent hyperhomocysteinaemia in homozygous mutant subjects.

Broad emission lines λλ 682.5, 708.2 nm, observed for years in the spectrum of symbiotic stars, have been identified by Schmid (1989) as due to Raman scattering of O VI 103.2, 103.6 nm by H0. In one symbiotic star, van Groningen (1993) detected Raman scattered He II.