Delayed neutrons measurement at the MEGAPIE target

In the framework of the Neutronic and Nuclear Assessment Task Group of the MEGAPIE experiment we measured the delayed neutron (DN) flux at the top of the target. The measurement was proposed mainly for radioprotection purposes since the DN flux at the top of the target has been estimated to be of the same order of magnitude as the prompt neutron flux. Given the strong model-dependence of DN predictions, the measurement of DN contribution to the total neutron activity at the top of the target was thus desired. Moreover, this measurement is complementary to the DN experiments performed at PNPI (Gatchina) on solid lead and bismuth targets. The DN measurement at MEGAPIE was performed during the start-up phase of the target. In this paper we present a detailed description of the experimental setup and some preliminary results on decay spectra.Comment: 4 pages, 4 figures, Proceedings of International Conference on Nuclear Data for Science and Technology (ND 2007), Nice, France, 22-27 Apr 200

Intervening Metal Systems in GRB and QSO sight-lines: The Mgii and Civ Question

Prochter et al. 2006 recently found that the number density of strong intervening 0.5<z<2 MgII absorbers detected in gamma-ray burst (GRB) afterglow spectra is nearly 4 times larger than in QSO spectra. We have conducted a similar study using CIV absorbers. Our CIV sample, consisting of a total of 20 systems, is drawn from 3 high resolution and high to moderate S/N VLT/UVES spectra of 3 long-duration GRB afterglows, covering the redshift interval 1.6< z<3.1. The column density distribution and number density of this sample do not show any statistical difference with the same quantities measured in QSO spectra. We discuss several possibilities for the discrepancy between CIV and MgII absorbers and conclude that a higher dust extinction in the MgII QSO samples studied up to now would give the most straightforward solution. However, this effect is only important for the strong MgII absorbers. Regardless of the reasons for this discrepancy, this result confirms once more that GRBs can be used to detect a side of the universe that was unknown before, not necessarily connected with GRBs themselves, providing an alternative and fundamental investigative tool of the cosmic evolution of the universe.Comment: 21 pages, 4 figures, ApJ accepted, Revised after Referee Repor

Statistics and characteristics of MgII absorbers along GRB lines of sight observed with VLT-UVES

We analyse the properties of MgII absorption systems detected along the sightlines toward GRBs using a sample of 10 GRB afterglow spectra obtained with VLT-UVES over the past six years. The S/N ratio is sufficiently high that we can extend previous studies to smaller equivalent widths (typically Wr>0.3A). Over a pathlength of Delta(z)~14 the number of weak absorbers detected is similar along GRB and QSO lines of sight, while the number of strong systems is larger along GRB lines of sight with a 2-sigma significance. Using intermediate and low resolution observations reported in the literature, we increase the absorption length for strong systems to Delta(z)=31.5 (about twice the path length of previous studies) and find that the number density of strong MgII systems is a factor of 2.1+/-0.6 higher (about 3-sigma significance) toward GRBs as compared to QSOs, about twice smaller however than previously reported. We divide the sample in three redshift bins and we find that the number density of strong MgII is larger in the low redshift bins. We investigate in detail the properties of strong MgII systems observed with UVES. Both the estimated dust extinction in strong GRB MgII systems and the equivalent width distribution are consistent with what is observed for standard QSO systems. We find also that the number density of (sub)-DLAs per unit redshift in the UVES sample is probably twice larger than what is expected from QSO sightlines which confirms the peculiarity of GRB lines of sight. These results indicate that neither a dust extinction bias nor different beam sizes of the sources are viable explanations for the excess. It is still possible that the current sample of GRB lines of sight is biased by a subtle gravitational lensing effect. More data and larger samples are needed to test this hypothesis. (abridged)Comment: 12 pages, 10 figures; accepted for publication in A&A (12 June 2009

Kinetic modeling of carbon dioxide valorization with epoxides

The reaction between carbon dioxide and epoxides using a non-metallic catalytic system can produce cyclic carbonates with excellent yields. The activation of the chemical system can occur in two ways: activation of epoxide or activation of carbon dioxide at the first step. A kinetic investigation of epichlorohydrin carbonate synthesis from epichlorohydrin and carbon dioxide was performed. The mass transfer, the kinetic of reaction and the activation of the chemical system was included in the analysis. A kinetic model was developed based on the reaction mechanism and the mass transfer phenomena. The quasi steady state assumption was considered on intermediate species and its results were compared with the detailed model. The optimization of the kinetic parameters estimated was performed by using a genetic algorithm in the model, the results obtained were in agreement with the experimental data. Please click Additional Files below to see the full abstract

The STICS model to predict nitrate leaching following agricultural pratices.

The aim of this paper was to develop an upscaling approach for the soil-crop model STICS in order to predict the impact of agricultural practices on nitrate leaching on both plot and regional scales. A case study was carried out on a "Nitrate Vulnerable Zone" located in central France. The performance of the spatial approach was evaluated by accounting for all the spatial and temporal variability existing within the studied area. The results indicate that N leaching and nitrate concentration in drainage water were slightly underestimated; by 3 kg N·ha-1 (16%) and 8 mg NO3-·L-1 (11%), respectively. The STICS scaling approach was used to assess the effectiveness of "Good Agricultural Practice" established within the area over a seven-year period. The simulation results provided evidence that such a practice had reduced the nitrate concentration by about 30% (36 mg NO3-·L-1). However, the rate of nitrate leaching remains too large and further improvements to agricultural practices are required

Les apports de l'ergonomie participative dans le cadre de projets industriels ou architecturaux

Une approche ergonomique est ici présentée comme un moyen d'améliorer les conditions d'exécution du travail en intervenant lors de projets d'investissement. Cette approche s'appuie sur l'analyse de l'activité en situation réelle et s'articule aux structures mises en place pour la réalisation du projet en accordant une place importante aux travailleurs visés. Sur la base de trois interventions, l'article tente d'illustrer l'intérêt de recourir à cette approche pour optimiser les projets en intégrant une prise en compte de l'activité humaine.Investment projects, whether they involve new technologies or the design of new buildings, may provide ergonomists with the opportunity to participate in optimizing the design of new work situations. The future activity approachhas been developed to allow ergonomic involvement during the design process. This approach has two main aspects: it is based on "real work" as proposed by French ergonomics; and it considers the design process as a process of social interaction. The ergonomic intervention in this approach therefore requires observations in real work situations, carried out on reference sites. These sites can be situations to be changed or situations with characteristics similar to those that are to be changed. Using these analyses, the ergonomist participates in the design process. His role or her role is to retrace typical action situationson the reference sites so that the designers' proposais can be tested through human activity, or so that design criteriacan be developed. In a project, several areas of design can be the focus of ergonomic action: space, the technical device, work organization, and training. The future activity approach assumes that the ergonomic involvement is based on the company structures. By considering design as a process involving several actors (designers, managers, employees), the ergonomist makes use of the abilities of many different participants to carry out the reference site analysis as well as to anticipate the future activity and enhance the outcome of the project through design criteria. Participatory structures, in which the ergonomist plays an important role, are organized in such a way as to allow these abilities to be used. To illustrate how this approach is applied, three different interventions are presented. They are based on the same approach, but differ in certain respects due to the uniqueness of the projects and the contexts involved.First, in a project to reorganize production in a poultry slaughterhouse, the presence of working groups allowed variability (of people, raw materials, tools) to be better taken into account in the planned facilities. Second, in the design of a new residential and extended-care centre, the ergonomists enhanced the architectural program by becoming involved very early in the process. The working groups in fact revealed working methodsdeveloped by the employees, so that programming could focus on these aspects rather than on standards and regulations. Lastly, an ergonomic intervention during the modernization of a newspaper printing plant shows that reconstitution of the future activityallows not only modifications to improve a proposed project, but also an evolution in the representations that the different participants have of the work situations and, consequently of the relationships between them. These examples of involvement in various projects also point to the conditions that favour an ergonomic intervention which satisfies criteria to improve not only the health and safety of people, but also production efficiency. The care that is given to the social construction of the intervention has an impact on the ease of implementation of the structures and the rules of the game discussed and accepted by the parties involved. For example, a structure that manages the intervention (follow-up group) should probably be separated from another that participates more directly in the activity analyses and reconstitutions (working group). Early involvement in the projects allows more leeway in the changes to be made. Furthermore, by participating throughout the project in social interactions in a structure planned for this purpose, the ergonomist is better able to achieve something positive than if he or she adheres to recommendations produced at a given time in the process.We believe that a project to change work situations is an interesting opportunity to create synergy between the resources assigned to prevention and those responsible for improving production. The future activity approach seems to be a suitable process for this

Carboxylation des alcools/diols avec le CO2 en présence d'un agent déshydratant : détermination des paramètres thermodynamiques

National audienc

Three intervening galaxy absorbers towards GRB060418: faint and dusty?

We present an analysis of three strong, intervening Mg II absorption systems (z_abs = 0.603, 0.656, 1.107) towards the optical afterglow of gamma-ray burst (GRB) 060418. From high resolution UVES spectra we measure metal column densities and find that the highest redshift absorber exhibits a large amount of dust depletion compared with DLAs seen in QSO spectra. The intervening z_abs = 1.107 absorber is also unusual in exhibiting a clear 2175 A bump, the first time this feature has been definitively detected in a GRB spectrum. The GRB afterglow spectrum is best fit with a two component extinction curve: an SMC extinction law at z=1.49 (the redshift of the host) with E(B-V) = 0.07+-0.01 and a Galactic extinction curve at z ~ 1.1 with E(B-V) = 0.08+-0.01. We also present a moderately deep NTT R-band image of the GRB060418 field and spectroscopy of four galaxies within 1 arcminute. None of these objects has a redshift that matches any of the intervening absorbers, and we conclude that the galaxies responsible for the two intervening Mg II absorbers at z ~ 0.6 have luminosities ~<0.3 L^star.Comment: Accepted for publication in MNRAS (Letters), 5 pages. Updated with more accurate host positio

The gray matter volume of the amygdala is correlated with the perception of melodic intervals: a voxel-based morphometry study

Music is not simply a series of organized pitches, rhythms, and timbres, it is capable of evoking emotions. In the present study, voxel-based morphometry (VBM) was employed to explore the neural basis that may link music to emotion. To do this, we identified the neuroanatomical correlates of the ability to extract pitch interval size in a music segment (i.e., interval perception) in a large population of healthy young adults (N = 264). Behaviorally, we found that interval perception was correlated with daily emotional experiences, indicating the intrinsic link between music and emotion. Neurally, and as expected, we found that interval perception was positively correlated with the gray matter volume (GMV) of the bilateral temporal cortex. More important, a larger GMV of the bilateral amygdala was associated with better interval perception, suggesting that the amygdala, which is the neural substrate of emotional processing, is also involved in music processing. In sum, our study provides one of first neuroanatomical evidence on the association between the amygdala and music, which contributes to our understanding of exactly how music evokes emotional responses