Uniqueness of the self-similar profile for a kinetic annihilation model

We show the existence of a self-similar solution for a We prove the uniqueness of the self-similar profile solution for a modified Boltzmann equation describing probabilistic ballistic annihilation. Such a model describes a system of hard spheres such that, whenever two particles meet, they either annihilate with probability $\alpha \in (0,1)$ or they undergo an elastic collision with probability $1-\alpha$. The existence of a self-similar profile for $\alpha$ smaller than an explicit threshold value $\underline{\alpha}_1$ has been obtained in our previous contribution (J. Differential Equations, 254, 3023--3080, 2013). . We complement here our analysis of such a model by showing that, for some $\alpha^{\sharp}$ explicit, the self-similar profile is unique for $\alpha \in (0,\alpha^{\sharp})$

Existence of self-similar profile for a kinetic annihilation model

We show the existence of a self-similar solution for a modified Boltzmann equation describing probabilistic ballistic annihilation. Such a model describes a system of hard-spheres such that, whenever two particles meet, they either annihilate with probability $\alpha \in (0,1)$ or they undergo an elastic collision with probability $1 - \alpha$. For such a model, the number of particles, the linear momentum and the kinetic energy are not conserved. We show that, for $\alpha$ smaller than some explicit threshold value $\alpha_*$, a self-similar solution exists.Comment: This new version supersedes and replaces the previous one. We found a mistake in the previous (and published) version of the manuscript and explained how to fix it in "Erratum to "Existence of self-similar profile for a kinetic annihilation model" [J. Differential Equations 254 (7) (2013) 3023-3080]. J. Differential Equations 257 (2014), no. 8, 3071-3074." This version provides a complete and corrected version of the previous manuscrip

A multiplex oligonucleotide ligation-PCR as a complementary tool for subtyping of Salmonella Typhimurium

Subtyping below the serovar level is essential for surveillance and outbreak detection and investigation of Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) and its monophasic variant 1,4,[5],12:i:- (S. 1,4,[5],12:i:-), frequent causes of foodborne infections. In an attempt to overcome the intrinsic shortcomings of currently used subtyping techniques, a multiplex oligonucleotide ligation-PCR (MOL-PCR) assay was developed which combines different types of molecular markers in a high throughput microsphere suspension array. The 52 molecular markers include prophage genes, amplified fragment length polymorphism (AFLP) elements, Salmonella genomic island 1 (SGI1), allantoinase gene allB, MLVA locus STTR10, antibiotic resistance genes, single nucleotide polymorphisms (SNPs) and phase 2 flagellar gene fljB. The in vitro stability of these markers was confirmed in a serial passage experiment. The validation of the MOL-PCR assay for subtyping of S. Typhimurium and S. 1,4,[5],12:i:- on 519 isolates shows that the method is rapid, reproducible, flexible, accessible, easy to use and relatively inexpensive. Additionally, a 100 % typeability and a discriminatory power equivalent to that of phage typing were observed, and epidemiological concordance was assessed on isolates of 2 different outbreaks. Furthermore, a data analysis method is provided so that the MOL-PCR assay allows for objective, computerised data analysis and data interpretation of which the results can be easily exchanged between different laboratories in an international surveillance network

p25/Cdk5-mediated retinoblastoma phosphorylation is an early event in neuronal cell death

In large models of neuronal cell death, there is a tight correlation between Cdk5 deregulation and cell-cycle dysfunction. However, pathways that link Cdk5 to the cell cycle during neuronal death are still unclear. We have investigated the molecular events that precede p25/Cdk5-triggered neuronal death using a neuronal cell line that allows inducible p25 expression. In this system, no sign of apoptosis was seen before 24 hours of p25 induction. Thus, at that time, cell-cycle-regulatory proteins were analysed by immunoblotting and some of them showed a significant deregulation. Interestingly, after time-course experiments, the earliest feature correlated with p25 expression was the phosphorylation of the retinoblastoma protein (Rb). Indeed, this phosphorylation was observed 6 hours after p25 induction and was abolished in the presence of a Cdk5 inhibitor, roscovitine, which does not inhibit the usual Rb cyclin-D kinases Cdk4 and Cdk6. Furthermore, analyses of levels and subcellular localization of Cdk-related cyclins did not reveal any change following Cdk5 activation, arguing for a direct effect of Cdk5 activity on Rb protein. This latter result was clearly demonstrated by in vitro kinase assays showing that the p25-Cdk5 complex in our cell system phosphorylates Rb directly without the need for any intermediary kinase activity. Hence, Rb might be an appropriate candidate that connects Cdk5 to cell-cycle deregulation during neuronal cell death

Modélisation du processus d'apparition de données de défaillances de composants de centrale thermique et détermination de l'impact des conditions d'exploitation sur ces composants

International audienceLa présente étude a pour but de déterminer l'impact du mode de conduite d'une tranche thermique à flamme type charbon ou fuel, sur la fiabilité des composants de la chaudière. L'analyse a été menée sur un composant d'une chaudière du parc thermique à flamme d'EDF. La problématique sélectionnée représente un pourcentage important des fuites chaudières. Les paramètres d'influence possibles du processus de défaillance étudié sont les paramètres qui caractérisent le mode d'exploitation de la tranche : nombres d'heures de fonctionnement tous types (marche réelle et attente en disponibilité) ainsi que les nombres de démarrages tous types (à chaud, tièdes et à froid). La démarche statistique est la suivante : · Statistiques descriptives sur l'ensemble des données ; · Recherche des paramètres influents parmi les paramètres d'exploitation disponibles du mécanisme de défaillance (modèles linéaires généralisés) ; · Tests de constance du taux de défaillance (tests sur l'homogénéité du processus de Poisson) ; · Identification des paramètres du modèle du processus des défaillances, en fonction du principal paramètre influent identifié; · Pronostic des futures défaillances en fonction d'un mode d'exploitation. L'étape 2 a permis d'identifier que le nombre de démarrages à chaud était le paramètre influent principal du processus de défaillance étudié. Les différents tests statistiques réalisés ont permis par ailleurs de montrer que le processus était homogène. Enfin la dernière étape a permis de construire un nombre prévisionnel de défaillance, pour un mode d'exploitation donné, sur les années à venir. Cette estimation permet de quantifier l'impact des démarrages-arrêts sur la fiabilité de l'installation et d'estimer en conséquence le coût dû à une modification de l'exploitation de la tranche

Modeling δ15N evolution: First palaeoceanographic applications in a coastal upwelling system

The δ15N signal in marine sediments appears to be a good palaeoceanographic tracer. It records biological processes in the water column and is transferred to and preserved in the sediments. Changes in forcing factors in upwelling systems may be recorded by δ15N. These forcing conditions can be of a biogeochemical nature, such as the initial isotopic signal of the nutrients or the trophic structure, or of a physical nature, such as wind stress, insolation, temperature or dynamic recycling. A simple nitrogen-based trophic chain model was used to follow the development of the nitrogen isotopic signal in nutrients, phytoplankton, zooplankton and detritus. Detrital δ15N, influenced by the isotopic signature of the upwelled nutrients and isotopic fractionation along the trophic chain (photosynthesis and zooplankton excretion), was then compared to the sedimentary signal measured off Mauritania. In our model, the biological variables are transported at shallow depths by a simple circulation scheme perpendicular to the coast depicting a continental shelf recirculation cell. Because cell length depends on the extension of the continental shelf, modifications of the cell length mimic sea level changes. Long cell length (high sea level) scenarios produce higher δ15N values whereas short cell length scenarios result in lower values as in the glacial low sea level periods. Despite changes in many climatic parameters throughout this period, our results show that changing the sea level is sufficient to reconstruct the main pattern of the sedimentary δ15N variations offshore of the Mauritanian upwelling, i.e. an increase from about 3‰ to 7‰ during the deglaciation, without invoking any change in nitrogen fixation or denitrification

Solutions to Landau equation under Prodi-Serrin's like criteria

In this paper, we introduce Prodi-Serrin like criteria for weak solutions under which it is possible to show existence of classical solutions to the spatially homogeneous Landau equation for all classical potentials and dimensions $d \ge 3$. The physical case of Coulomb interaction in dimension $d=3$ is included in our analysis, which generalizes the work of \cite{silvestre}. The first step consists in establishing instantaneous appearance of $L^{p}$ estimates using the Prodi-Serrin criteria. Then, we introduce a new $L^{p}$ to $L^{\infty}$ framework, using a suitable De Giorgi's argument reminiscent of the one found in \cite{ricardo}, which provides appearance of pointwise bounds for such solutions. Our approach is quantitative and does not require a preliminary knowledge of elaborate tools for nonlinear parabolic equations

Nanodevices for correlated electrical transport and structural investigation of individual carbon nanotubes

We report a new approach to the correlation of the structural properties and the transport properties of carbon nanotubes. Through an original combination of UV lithography, custom-made photosensitive sol–gel resist and deep reactive ion etching (RIE), we have successfully integrated membrane technology and nanodevice fabrication for the electrical connection of individual carbon nanotubes. After single wall nanotube (SWNT) deposition by molecular combing and contacting using high resolution electron beam lithography, we obtain a device that allows both the investigation of the nanotubes and the contact regions by transmission electron microscopy (TEM) and the measurement of the electronic transport properties of the same individual nano-object. The whole fabrication process is detailed and the demonstration that the micro membranes are suitable for both TEM inspection and nanoelectrode fabrication is given