Characterising small solutions in delay differential equations through numerical approximations

This paper discusses how the existence of small solutions for delay differential equations can be predicted from the behaviour of the spectrum of the finite dimensional approximations.Manchester Centre for Computational Mathematic

A sharp version of Henry's theorem on small solutions

AbstractA small solution of a linear autonomous retarded functional differential equation (rfde) is a solution that goes to zero faster than any exponential. Henry's theorem on small solutions states that there exists a time T—depending on the dimension and the delay of the equation—such that all small solutions vanish a.e. for t ⩾ T. In this paper we shall give an explicit characterisation for the smallest possible time T, in terms of properties of the specific kernel. This characterisation helps to establish new results concerning completeness and F-completeness of the generalized eigenfunctions of the infinitesimal generator of the C0-semigroup associated with the linear autonomous rfde

The Formation, Structure, and Stability of a Shear Layer in a Fluid with Temperature-Dependent Viscosity

The presence of viscosity normally has a stabilizing effect on the flow of a fluid. However, experiments show that the flow of a fluid might form shear bands or shear layers, narrow bands in which the velocity of the fluid changes sharply. In general, adiabatic shear layers are observed not only in fluids but also in thermo-plastic materials subject to shear at a high-strain rate and in combustion. Therefore there is widespread interest in modeling the formation of shear layers. In this paper we investigate the basic system of conservation laws for a one-dimensional flow with temperature-dependent viscosity using a combination of analytical and numerical tools. We present results to substantiate the claim that the formation of shear layers is due to teh fact that viscosity decreases sufficiently quickly as temperature increases and analyze the structure and stability properties of the layers

Données épidémiologiques dans le monde et traitements disponibles du VHB

Date du colloque&nbsp;: 09/2008</p

The potential for reassortment between Oropouche and Schmallenberg Orthobunyaviruses

A number of viruses within the Peribunyaviridae family are naturally occurring reassortants, a common phenomenon for segmented viruses. Using a minigenome-reporter and virus-like particle (VLP) production assay, we have accessed the potential of Oropouche virus (OROV), Schmallenberg virus (SBV), and other orthobunyaviruses within the Simbu serogroup to reassort. We found that the untranslated region (UTR) in the medium segment is a potential contributing factor for reassortment by the tested viruses. We demonstrate that for promoter activity to occur it was essential that the viral RNA polymerase (L) and nucleocapsid (N) proteins were from the same virus, reinforcing the hypothesis that the large and small segments that encode these proteins segregate together during genome reassortment. Our results indicate that, given the right epidemiological setting, reassortment between SBV and OROV would potentially be feasible and could contribute to the emergence of a new Simbu virus

Traitement des hépatites B, C, D

Les hépatites virales sont un problème majeur de santé publique au niveau international. Environ 2 milliards de sujets dans le monde ont été en contact avec le VHB, soit qu\u27ils aient une infection, soit qu\u27ils aient éliminé partiellement le virus [1]. Quatre cents millions d\u27individus sont porteurs chroniques d\u27une infection par le virus de l\u27hépatite B (VHB) et parmi ceux-ci, environ à 15 millions sont co-infectés par un virus satellite du virus de l\u27hépatite B appelé le virus de l\u27hépatite Delta (VHD).Dans le monde, près de 200 millions de sujets sont également infectés par le virus de l\u27hépatite C [2]. Les chiffres concernant la mortalité et la morbidité globale de ces infections sont partiellement connus. L\u27OMS estime qu\u27environ 2 millions de décès par an sont dus aux infections par les virus des hépatites C (http://www.who.int/fr/). On sait également que les patients porteurs d\u27une infection chronique ont un risque majeur d\u27évoluer vers la cirrhose du foie et le carcinome hépato-cellulaire (le risque serait de 200 par rapport à un sujet non infecté [3, 4] ). Dans les pays développés, les hépatites B et C sont également responsables d\u27une grande partie des transplantations hépatiques [1] . L\u27objectif de cette revue est de faire le point sur le traitement des hépatites B, C et Delta en envisageant les schémas thérapeutiques les plus adaptés à l\u27Afrique. Nous aborderons d\u27abord le traitement des hépatites B, le traitement des co-infections B-Delta, le traitement des hépatites B chez les patients VIH puis le traitement des hépatites C et celui des hépatites C chez les patients vivant avec le VIH