A Markov Chain Monte Carlo technique to sample transport and source parameters of Galactic cosmic rays: II. Results for the diffusion model combining B/C and radioactive nuclei

On-going measurements of the cosmic radiation (nuclear, electronic, and gamma-ray) are shedding new light on cosmic-ray physics. A comprehensive picture of these data relies on an accurate determination of the transport and source parameters of propagation models. A Markov Chain Monte Carlo is used to obtain these parameters in a diffusion model. From the measurement of the B/C ratio and radioactive cosmic-ray clocks, we calculate their probability density functions, with a special emphasis on the halo size L of the Galaxy and the local underdense bubble of size r_h. The analysis relies on the USINE code for propagation and on a Markov Chain Monte Carlo technique (Putze et al. 2009, paper I of this series) for the parameter determination. As found in previous studies, the B/C best-fit model favours diffusion/convection/reacceleration (Model III) over diffusion/reacceleration (Model II). A combined fit on B/C and the isotopic ratios (10Be/9Be, 26Al/27Al, 36Cl/Cl) leads to L ~ 8 kpc and r_h ~ 120 pc for the best-fit Model III. This value for r_h is consistent with direct measurements of the local interstallar medium. For Model II, L ~ 4 kpc and r_h is consistent with zero. We showed the potential and usefulness of the Markov Chain Monte Carlo technique in the analysis of cosmic-ray measurements in diffusion models. The size of the diffusive halo depends crucially on the value of the diffusion slope delta, and also on the presence/absence of the local underdensity damping effect on radioactive nuclei. More precise data from on-going experiments are expected to clarify this issue.Comment: 20 pages, 14 figures, minor language corrections to match the A&A accepted versio

Nuclear Cosmic Rays propagation in the Atmosphere

The transport of the nuclear cosmic ray flux in the atmosphere is studied and the atmospheric corrections to be applied to the measurements are calculated. The contribution of the calculated corrections to the accuracy of the experimental results are discussed and evaluated over the kinetic energy range 10-10$^{3}$ GeV/n. The Boron (B) and Carbon (C) elements system is used as a test case. It is shown that the required corrections become largely dominant at the highest energies investigated. The results are discussed.Comment: Proc. of 30th International Cosmic Ray Conference, Merida, Mexico; 4 page

Le Christ et les prophètes dans le Traité Théologico-politique

Dans le Traité Théologico-politique, Spinoza formule plusieurs critiques à l’endroit de la prophétie hébraïque : celle-ci se serait avouée incapable de formuler clairement les règles morales, pourtant fort simples, nécessaires à l’obéissance et au salut. Ces reproches se doublent par ailleurs d’une relative apologie du christianisme ou plus exactement de son fondateur, Jésus-Christ. Le Christ aurait en effet réussi là où toute la tradition prophétique avait avant lui échoué, c’est-à- dire qu’il a conçu Dieu de manière intellectuelle et, de ce fait, est parvenu à énoncer la loi divine dans un langage simple, intelligible au vulgaire. Dans cet article, nous proposons une comparaison entre le Christ et les prophètes. Il s’agira d’abord de voir en quoi la connaissance christique supplante la connaissance prophétique, pour ensuite tâcher de préciser quelles sont, quant à la personne du Christ, les conséquences exactes de cet ascendant épistémologique

The use of Walsh functions in the determination of three-dimensional refractive index distributions, and other density fields, from experimental data

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Simulation of neutrino and charged particle production and propagation in the atmosphere

A precise evaluation of the secondary particle production and propagation in the atmosphere is very important for the atmospheric neutrino oscillation studies. The issue is addressed with the extension of a previously developed full 3-Dimensional Monte-Carlo simulation of particle generation and transport in the atmosphere, to compute the flux of secondary protons, muons and neutrinos. Recent balloon borne experiments have performed a set of accurate flux measurements for different particle species at different altitudes in the atmosphere, which can be used to test the calculations for the atmospheric neutrino production, and constrain the underlying hadronic models. The simulation results are reported and compared with the latest flux measurements. It is shown that the level of precision reached by these experiments could be used to constrain the nuclear models used in the simulation. The implication of these results for the atmospheric neutrino flux calculation are discussed.Comment: 11 pages, 9 figure

The Demand for Directors' and Officers' Insurance in Canada

This paper looks at the insurance demand of a firm's directors and officers using a sample of Canadian corporations (excluding firms from the Financial services and Mining sectors) from 1993-1999. More to the point, we study the demand for director's and officer's insurance. Our results suggest that larger corporation are more likely to purchase D&O insurance. Firms that are strong financially are less likely to purchase D&O insurance. Firms are also less likely to purchase D&O insurance when there are many outsiders on the board of directors and when the board member have an important financial stake in the corporation. Surprisingly, being listed on a stock exchange in the United States does not seem to have an impact on the demand for D&O insurance, contrary to previous results. Cette recherche se penche sur la demande d'assurance de la responsabilité civile des administrateurs et des dirigeants d'entreprise en utilisant des données pour plus de 350 compagnies canadiennes entre 1993 et 1999. Les firmes dans les secteurs des services financiers et des mines ne sont pas inclues. Plus précisément, nous nous intéressons à la demande d'assurance de la responsabilité civile des administrateurs et des dirigeants. Nos résultats suggèrent qu'il est plus probable pour une corporation de grande taille d'avoir une assurance D&O que pour une corporation de petite taille. Les corporations qui ont une bonne santé financière ont moins de chance d'avoir une assurance, tout comme les corporations où la présence d'administrateurs indépendants au conseil d'administration est importante. De plus, plus les membres des conseils d'administration sont impliqués financièrement dans la santé d'une corporation, moins importante est la probabilité que cette compagnie possède une assurance D&O. Un résultat surprenant que nous obtenons est le fait que d'être enregistré dans une bourse américaine ne semble pas avoir d'impact sur la demande d'assurance D&O, contrairement aux études précédentes.Executive Compensation, D&O Insurance, Rémunération des dirigeants, assurance D&O