Le thon : enjeux et stratégies pour l'océan Indien

La nécessité de prendre en compte le caractère migratoire des espèces océaniques de thons entraîne l'élaboration d'une politique de gestion des ressources coordonnées à l'échelle internationale et à l'échelle des océans. Cette politique implique l'élaboration et l'intégration de programmes de recherche destinés à préparer les mesures d'aménagement des pêcheries. Cette recherche intégrée régionalement doit comprendre des actions dans le domaine des sciences sociales et de l'économie des ressources naturelles. (Résumé d'auteur

Anharmonic force field and vibrational frequencies of tetrafluoromethane (CF4_4) and tetrafluorosilane (SiF4_4)

Accurate quartic anharmonic force fields for CF$_4$ and SiF$_4$ have been calculated using the CCSD(T) method and basis sets of $spdf$ quality. Based on the {\it ab initio} force field with a minor empirical adjustment, the vibrational energy levels of these two molecules and their isotopomers are calculated by means of high order Canonical Van Vleck Perturbation Theory(CVPT) based on curvilinear coordinates. The calculated energies agree very well with the experimental data. The full quadratic force field of CF$_4$ is further refined to the experimental data. The symmetrization of the Cartesian basis for any combination bands of $T_d$ group molecules is discussed using the circular promotion operator for the doubly degenerate modes, together with tabulated vector coupling coefficients. The extraction of the spectroscopic constants from our second order transformed Hamiltonian in curvilinear coordinates is discussed, and compared to a similar procedure in rectilinear coordinates.Comment: (submitted to J. Chem. Phys.

Unitary plate electrode

The unitary electrode (10) comprises a porous sheet (12) of fiberglass the strands (14) of which contain a coating (16) of conductive tin oxide. The lower portion of the sheet contains a layer (18) of resin and the upper layer (20) contains lead dioxide forming a positive active electrode on an electrolyte-impervious layer. The strands (14) form a continuous conduction path through both layers (16, 18). Tin oxide is prevented from reduction by coating the surface of the plate facing the negative electrode with a conductive, impervious layer resistant to reduction such as a thin film (130) of lead or graphite filled resin adhered to the plate with a layer (31) of conductive adhesive. The plate (10) can be formed by casting a molten resin from kettle (60) onto a sheet of glass wool (56) overlying a sheet of lead foil and then applying positive active paste from hopper (64) into the upper layer (68). The plate can also be formed by passing an assembly of a sheet ( 80) of resin, a sheet (86) of sintered glass and a sheet (90) of lead between the nip (92) of heated rollers (93, 95) and then filling lead oxide into the pores (116) of the upper layer (118)

On line clinical reasoning assessment with Script Concordance test in urology: results of a French pilot study

BACKGROUND: The Script Concordance test (SC) test is an assessment tool that measures the capacity to solve ill-defined problems, that is, reasoning in a context of uncertainty. This study assesses the feasibility, reliability and validity of the SC test made available on the Web to French urologists. METHODS: A 97 items SC test was developed based on major educational objectives of French urology training programmes. A secure Web site was created with two sequential modules: a) The first one for the reference panel to elaborate the scoring system; b) The second for candidates with different levels of experience in urology: Board certified urologists, chief-residents, residents, medical students. All participants were recruited on a voluntary basis. Statistical analysis included descriptive statistics of the participants' scores and factorial analysis of variance (ANOVA) to study differences between groups' means. Reliability was evaluated with Cronbach's alpha coefficient. RESULTS: The on line SC test has been operational since June 2004. Twenty-six faculty members constituted the reference panel. During the following 10 months, 207 participants took the test online (124 urologists, 29 chief-residents, 38 residents, 16 students). No technical problem was encountered. Forty-five percent of the participants completed the test partially only. Differences between the means scores for the 4 groups were statistically significant (P = 0.0123). The Bonferroni post-hoc correction indicated that significant differences were present between students and chief-residents, between students and urologists. There were no differences between chief-residents and urologists. Reliability coefficient was 0.734 for the total group of participants. CONCLUSION: Feasibility of Web-based SC test was proved successful by the large number of participants who participated in a few months. This Web site has permitted to quickly confirm reliability of the SC test and develop strategy to improve construct validity of the test when applied in the field of urology. Nevertheless, optimisation of the SC test content, with a smaller number of items will be necessary. Virtual medical education initiative such as this SC test delivered on the Internet warrants consideration in the current context of national pre-residency certification examination in France

Small denominators, frequency operators, and Lie transforms for nearly integrable quantum spin systems

Based on the previously proposed notions of action operators and of quantum integrability, frequency operators are introduced in a fully quantum-mechanical setting. They are conceptually useful because another formulation can be given to unitary perturbation theory. When worked out for quantum spin systems, this variant is found to be formally equivalent to canonical perturbation theory applied to nearly integrable systems consisting of classical spins. In particular, it becomes possible to locate the quantum-mechanical operator-valued equivalent of the frequency denominators that may cause divergence of the classical perturbation series. The results that are established here link the concept of quantum-mechanical integrability to a technical question, namely, the behavior of specific perturbation series

Chaos assisted tunnelling with cold atoms

In the context of quantum chaos, both theory and numerical analysis predict large fluctuations of the tunnelling transition probabilities when irregular dynamics is present at the classical level. We consider here the non-dissipative quantum evolution of cold atoms trapped in a time-dependent modulated periodic potential generated by two laser beams. We give some precise guidelines for the observation of chaos assisted tunnelling between invariant phase space structures paired by time-reversal symmetry.Comment: submitted to Phys. Rev. E ; 16 pages, 13 figures; figures of better quality can be found at http://www.phys.univ-tours.fr/~mouchet

Signatures of chaotic tunnelling

Recent experiments with cold atoms provide a significant step toward a better understanding of tunnelling when irregular dynamics is present at the classical level. In this paper, we lay out numerical studies which shed light on the previous experiments, help to clarify the underlying physics and have the ambition to be guidelines for future experiments.Comment: 11 pages, 9 figures, submitted to Phys. Rev. E. Figures of better quality can be found at http://www.phys.univ-tours.fr/~mouchet

Online clinical reasoning assessment with the Script Concordance test: a feasibility study

BACKGROUND: The script concordance (SC) test is an assessment tool that measures capacity to solve ill-defined problems, that is, reasoning in context of uncertainty. This tool has been used up to now mainly in medicine. The purpose of this pilot study is to assess the feasibility of the test delivered on the Web to French urologists. METHODS: The principle of SC test construction and the development of the Web site are described. A secure Web site was created with two sequential modules: (a) The first one for the reference panel (n = 26) with two sub-tasks: to validate the content of the test and to elaborate the scoring system; (b) The second for candidates with different levels of experience in Urology: Board certified urologists, residents, medical students (5 or 6(th )year). Minimum expected number of participants is 150 for urologists, 100 for residents and 50 for medical students. Each candidate is provided with an individual access code to this Web site. He/she may complete the Script Concordance test several times during his/her curriculum. RESULTS: The Web site has been operational since April 2004. The reference panel validated the test in June of the same year during the annual seminar of the French Society of Urology. The Web site is available for the candidates since September 2004. In six months, 80% of the target figure for the urologists, 68% of the target figure for the residents and 20% of the target figure for the student passed the test online. During these six months, no technical problem was encountered. CONCLUSION: The feasibility of the web-based SC test is successful as two-thirds of the expected number of participants was included within six months. Psychometric properties (validity, reliability) of the test will be evaluated on a large scale (N = 300). If positive, educational impact of this assessment tool will be useful to help urologists during their curriculum for the acquisition of clinical reasoning skills, which is crucial for professional competence