Short communication: Biofilm production characterization of mecA and mecC methicillin-resistant Staphylococcus aureus isolated from bovine milk in Great Britain

Staphylococcus aureus is an important cause of contagious intramammary infection in dairy cattle and the ability to produce biofilm is considered to be an important virulence property in the pathogenesis of mastitis. The aim of this study was to characterize the biofilm formation capacity of methicillin-resistant S. aureus (MRSA), encoding mecA or mecC, isolated from bulk tank milk in Great Britain. For this purpose, 20 MRSA isolates were grown on microtiter plates to determine the biofilm production. Moreover, the presence of the intercellular adhesion genes icaA and icaD were analyzed by PCR. All the tested MRSA isolates were PCR positive for the ica genes and 10 of them (50%) produced biofilm in the microtiter plate assay. This is also the first demonstration of biofilm production by mecC MRSA

Host Sexual Dimorphism and Parasite Adaptation

Disease expression and prevalence often vary in the different sexes of the host. This is typically attributed to innate differences of the two sexes but specific adaptations by the parasite to one or other host sex may also contribute to these observations

Statistics modification under monomer coalescence

The diffusion and coalescence of individual atoms on a nanostructured surface are treated in a purely statistical way. From this,analytical formulas are derived which, from a known initial state, give the final cluster size distribution on a surface after thediffusion of all the individual atoms. Unexpectedly, it turns out that these formulas allow obtaining a statistical law giving thesize histogram of the clusters when only homogeneous nucleation occurs with a critical germ equal to 2, and in the situation wherenucleation starts once the deposition of the atoms is completed.La diffusion et la coalescence d'atomes individuels sur une surface nanostructurée est traitée d'une manière purement statistique. De cette étude, on déduit des formules analytiques qui, à partir d'une situation initiale connue, donnent la distribution finale des tailles des agrégats sur la surface après la diffusion des monomères. Inopinément, il se trouve que ces formules permettent l'obtention d'une loi statistique donnant l'histogramme des tailles des agrégats dans la situation où seule la germination homogène est à l’œuvre, avec un germe critique égal à 2, et dans le cas où la nucléation démarre après que le dépôt d'atomes soit terminé

Transition to Soft Chaos in the Vibrational Spectrum of the CS2 Molecule

International audienceIn the vibrational spectrum of the CS2 molecule, a clear transition in the ``staircase'' function N(E) has been observed for the first time at Ec~13 000 cm-1. The analysis for spectral correlations over short and large distances shows that this transition could be associated with a transition towards a classically chaotic regime. A vibrational spectrum of high quality has been obtained of the CS2 molecule in its fundamental electronic state. This spectrum of a single symmetry shows 966 purely vibrational levels (J''=0) up to 19 200 cm-1. The absolute precision of the measured position of the levels is 0.05 cm-1, and the dynamic intensity range is greater than 5000

Low temperature and low pressure CO oxidation on gold clusters supported on MgO(100)

CO oxidation has been investigated on Au/MgO(100) model catalysts at RT and low pressure. The gold particles prepared by UHV evaporation on clean MgO surfaces are characterized by HRTEM. The gold particles are FCC single crystals or multiple twins with five-fold symmetry. Infrared spectroscopy indicates that two types of adsorption sites are present which correspond to loosely and strongly bound CO. The equilibrium CO coverage for the strongly bound CO is smaller than 0.1 ML. CO titration experiments show that oxygen does not dissociate on the gold nanoparticles. The CO oxidation reaction is studied at RT by molecular beam methods. A steady state CO reaction probability up to 0.50 is measured, for the first time at low pressure, for gold particles with a mean size of 1.5 nm. A reaction mechanism is proposed in which CO adsorbed on low coordinated gold atoms reacts with oxygen adsorbed molecularly, possibly at the Au/MgO interface.

TITANIUM : SAPPHIRE LASER PUMPED BY COPPER VAPOR LASER

In this paper we describe the applications of a Ti:Sapphire laser pumped by a copper vapor laser (CVL). We calculated an constructed an astigmatically compensated cavity for CVL pumped solid state lasers. The characteristics of our laser are interesting in the application of spectroscopy. With intracavity experiments high sensitivity was obtained over a large spectral range. We demonstrate, using I2 as a test molecule, that the extreme sensitivity of intracavity stimulated emission pumping (SEP) is due to non-linear effects which result in mode-locking

Kinetic Monte Carlo simulation of the growth of metal clusters on regular array of defects on insulator

A Kinetic Monte Carlo simulation of the nucleation and growth of Pd clusters on a nanostructured alumina substrate is presented. The new Monte Carlo simulation program allows to derive the 3D shape of the growing clusters without performing a full all atoms simulation. The simulation shows, like in previous pure 2D simulations, that clusters nucleate exclusively on the defects of the nanostructure in a limited range of substrate temperature. Around 300 K, the clusters have a compact faceted shape and they grow, at not too large coverage, layer by layer. These results are in agreement with previous studies of the nucleation and growth of Pd clusters on an ultrathin alumina film on Ni3Al (1 1 1).Fil: Sitja, G.. Centre Interdisplinaire de Nanoscience de Marseille; FranciaFil: Uñac, Rodolfo Omar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico San Luis. Instituto de Física Aplicada; Argentina. Universidad Nacional de San Luis; ArgentinaFil: Henry, C. R.. Centre Interdisplinaire de Nanoscience de Marseille; Franci