International audienceThe Monte Carlo method is partially reviewed with the objective of illustrating how some of the most recent methodological advances can benefit to concentrated solar research. This review puts forward the practical consequences of writing down and handling the integral formulation associated to each Monte Carlo algorithm. Starting with simple examples and up to the most complex multiple reflection, multiple scattering configurations, we try to argue that these formulations are very much accessible to the non specialist and that they allow a straightforward entry to sensitivity computations (for assistance in design optimization processes) and to convergence enhancement techniques involving subtle concepts such as control variate and zero variance. All illustration examples makePROMES - UPR CNRS 8521 - 7, rue du Four Solaire, 66120 Font Romeu Odeillo, France use of the public domain development environment EDStar (including advanced parallelized computer graphics libraries) and are meant to serve as start basis either for the upgrading of existing Monte Carlo codes, or for fast implementation of ad hoc codes when specific needs cannot be answered with standard concentrated solar codes (in particular as far as the new generation of solar receivers is concerned). (C) 2013 Elsevier Ltd. All rights reserved

Pseudomonas aeruginosa is an opportunistic bacterial pathogen able to thrive in highly diverse ecological niches and to infect compromised patients. Its genome exhibits a mosaic structure composed of a core genome into which accessory genes are inserted en bloc at specific sites. The size and the content of the core genome are open for debate as their estimation depends on the set of genomes considered and the pipeline of gene detection and clustering. Here, we redefined the size and the content of the core genome of P. aeruginosa from fully re-analyzed genomes of 17 reference strains. After the optimization of gene detection and clustering parameters, the core genome was defined at 5,233 orthologs, which represented ~ 88% of the average genome. Extrapolation indicated that our panel was suitable to estimate the core genome that will remain constant even if new genomes are added. The core genome contained resistance determinants to the major antibiotic families as well as most metabolic, respiratory, and virulence genes. Although some virulence genes were accessory, they often related to conserved biological functions. Long-standing prophage elements were subjected to a genetic drift to eventually display a G+C content as higher as that of the core genome. This contrasts with the low G+C content of highly conserved ribosomal genes. The conservation of metabolic and respiratory genes could guarantee the ability of the species to thrive on a variety of carbon sources for energy in aerobiosis and anaerobiosis. Virtually all the strains, of environmental or clinical origin, have the complete toolkit to become resistant to the major antipseudomonal compounds and possess basic pathogenic mechanisms to infect humans. The knowledge of the genes shared by the majority of the P. aeruginosa isolates is a prerequisite for designing effective therapeutics to combat the wide variety of human infections.

A multiscale numerical model is developed to predict the thermal radiative properties (TRP) of rough La2NiO4+δ coatings. The model integrates intrinsic and extrinsic contributions related to the chemical composition and the texture, respectively. High-temperature infrared reflectivity and thermogravimetric measurements on a La2NiO4+δ single crystal make it possible to understand the role of the excess oxygen in the intrinsic TRP. We show that dense ceramics with thicknesses higher than 4 μm are optically thick, and that one can adjust the surface roughness parameters to predict their TRP.

We revisit the entropy formulation and the wave-front tracking construction of physically admissible solutions of the Aw-Rascle and Zhang (ARZ) second-order model for vehicular traffic. A Kruzhkov-like family of entropies is introduced to select the admissible shocks. This tool allows to define rigorously the appropriate notion of admissible weak solution and to approximate the solutions of the ARZ model with point constraint. Stability of solutions w.r.t. strong convergence is justified. We propose a finite volumes numerical scheme for the constrained ARZ, and we show that it can correctly locate contact discontinuities and take the constraint into account

No abstract

In the field of first-return statistics in bounded domains, short paths may be defined as those paths for which the diffusion approximation is inappropriate. However, general integral constraints have been identified that make it possible to address such short-path statistics indirectly by application of the diffusion approximation to long paths in a simple associated first-passage problem. This approach is exact in the zero Knudsen limit (Blanco S. and Fournier R., Phys. Rev. Lett., 97 (2006) 230604). Its generalization to the low to intermediate Knudsen range is addressed here theoretically and the corresponding predictions are compared to both one-dimension analytical solutions and three-dimension numerical experiments. Direct quantitative relations to the solution of the Schwarzschild-Milne problem are identified.

A numerical model based upon a Monte Carlo Ray Tracing (MCRT) code was developed to predict the thermal radiative properties (reflectance, transmittance, emittance) of a family of virtual alumina ceramics with prescribed textural features. The numerical samples were constituted of polydisperse spherical pores [20–120 μm] embedded in a continuous and homogenous alumina matrix. The texture of the alumina ceramics were numerically settled, allowing, in our case, to fix their porosity, their volumetric surface and their radii size distribution. The MCRT code was applied at T = 300 K and T = 1300 K since, at the local scale, the complex indices of refraction of the alumina matrix were known. The comparisons of the emittance spectra of the numerical samples with the ones acquired by infrared emittance spectroscopy on a single crystal of alumina (T = 300 K and T = 1300 K) allow to discuss the effects played by the temperature and by each textural parameters.

Thermal radiation is likely to play an important role in the calculation of the energy balance in solid oxide fuel cells (SOFCs), due to their high operating temperatures (6001-10001C). However, the majority of previous studies dealing with this issue have used room-temperature radiative data for determining the overall heat transfer process within a given cell, which could lead to an inexact appreciation of the role played by the thermal radiation. Consequently, the thermal field within the cell could also be incorrectly determined; however, accurate knowledge of the thermal field is important in order to understand the mechanical behavior of SOFCs. Several parameters, including chemical composition, texture, thickness, and of course operating temperature, have a large effect on the radiative properties of a given compound. As a first step to elucidate the temperaturedependent behavior of SOFCs, we deposited an La 2 NiO 41d cathodic layer on a planar ZrO 2 -8% Y 2 O 3 electrolyte-supported SOFC and investigated its radiative properties using hightemperature infrared emissivity spectroscopy (1001-9001C). Additional X-ray diffraction, thermo-gravimetric analysis, and environmental scanning electron microscopy measurements were also made to study the role played by both the chemical composition and texture on the radiative properties of the cell. 30 J. Stevenson-contributing editor *Member, The American Ceramic Society.