Fractional diffusion limit of a linear Boltzmann model with reflective boundaries in a half-space

We investigate the fractional diffusion limit of a Linear Boltzmann equation with heavy-tailed velocity equilibrium in a half-space with Maxwell boundary conditions. We derive a new confined version of the fractional Laplacian and show uniqueness of weak solutions to the associated non-local diffusion equation. This paper extends previous results of L. Cesbron, A. Mellet and M. Puel [5] on the same kinetic model with diffusive boundary conditions

Prion Replication in the Hematopoietic Compartment Is Not Required for Neuroinvasion in Scrapie Mouse Model

Fatal neurodegenerative prion diseases are caused by the transmissible PrPSc prion agent whose initial replication after peripheral inoculation takes place in follicular dendritic cells present in germinal centers of lymphoid organs. However, prion replication also occurs in lymphoid cells. To assess the role of the hematopoietic compartment in neuroinvasion and prion replication, we generated chimeric mice, on a uniform congenic C57/BL6J background, by bone marrow replacement with hematopoietic cells expressing different levels of PrP protein. Nine different types of chimeric mice were inoculated intraperitoneally either with the lymphotropic Rocky Mountain Laboratory (RML) strain or the non lymphotropic ME-7 scrapie strain, at different doses. Here, we clearly demonstrate that overexpression of PrP by the hematopoietic system, or the lack of PrP expression by the bone marrow derived cells, does not change the incubation time period of the disease, even when the mice are infected at limiting doses. We conclude that the hematopoietic compartment is more or less permissive to prion replication, both for RML and ME-7, but does not play a role in neuroinvasion

Protein flotation assay to isolate lipid rafts from soft tissue or cells

on-line protocol: Bio-protocol: http://www.bio-protocol.org/wenzhang.aspx?id=854The arrangement in eukaryotic cell membranes of liquid-ordered states surrounded by liquid-disordered phases allows for the existence of organized membrane microdomains called rafts. Rafts play a crusial role in signal-transduction events, in lipid transport and in various internalization processes, and for all these reasons need to be purified for further characterization

Cathodoluminescence of Rare Earth Doped Zircons. I. Their Possible Use as Reference Materials

Synthetic zircon crystals (ZrSiO4), undoped and doped with Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+, were grown from a flux consisting of a mixture of Li2MoO4 and MoO3 heated to 1125°C and then cooled to 750°C. The cathodoluminescence (CL) spectra of these zircons were analyzed at room-temperature and near liquid nitrogen temperature with a CL spectrometer attached to a scanning electron microscope (SEM). This study highlights the complexity of the intrinsic emission band extending from 200 to 500 nm. The relative intensities of the major emission band centered at 230 nm (5.4 eV) and peaks of less energy were found to depend upon the crystallographic orientation of the crystals. Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+ and Tm3+-doped zircons display sharp emission peaks being characteristic of the doping rare-earth element (REE). These lines are frequently multiplets but only the average position of the peaks are reported because of the instrumental conditions used in this study. The CL intensities of the intrinsic and extrinsic features were found to depend on the crystal orientation, and numerous experimental factors such as the electron beam energy and the beam current density

A fast method for computing convolutions with structural Green's functions: application to tyre dynamic contact problems

International audienceTyre/road contact is the main source of car noise at speeds greater than 50 km/h. In this context, we have developed a new approach for modelling tyre vibrations and contact with rigid road surfaces during rolling. For tyres, a periodic model is used to compute Green's functions. The response of tyres can, thus, be modelled over a large frequency range. Then, a fast convolution and a new contact model are developed and examples of computations of contact stress are given for real road textures. Spectra of stress for different tyre velocities are also compute