Martingales and Profile of Binary Search Trees

We are interested in the asymptotic analysis of the binary search tree (BST) under the random permutation model. Via an embedding in a continuous time model, we get new results, in particular the asymptotic behavior of the profile

Immunity against Helminths: Interactions with the Host and the Intercurrent Infections

Helminth parasites are of considerable medical and economic importance. Studies of the immune response against helminths are of great interest in understanding interactions between the host immune system and parasites. Effector immune mechanisms against tissue-dwelling helminths and helminths localized in the lumen of organs, and their regulation, are reviewed. Helminth infections are characterized by an association of Th2-like and Treg responses. Worms are able to persist in the host and are mainly responsible for chronic infection despite a strong immune response developed by the parasitized host. Two types of protection against the parasite, namely, premune and partial immunities, have been described. Immune responses against helminths can also participate in pathogenesis. Th2/Treg-like immunomodulation allows the survival of both host and parasite by controlling immunopathologic disorders and parasite persistence. Consequences of the modified Th2-like responses on co-infection, vaccination, and inflammatory diseases are discussed

La "question" de la responsabilité dans l'écriture de presse

L'écriture de presse, qui se donne volontiers le leurre légitimant de l'impartialité étayée par une conception réductrice d'un langage transparent et instrumentalisable (Koren 1996, 2004), est en fait travaillée par les tensions de la subjectivisation et de l'objectivisation. Elle joue un rôle essentiel dans la circulation des discours, dans la construction d'un « miroir social » en constant devenir et met notamment en spectacle de manière privilégiée les paroles d'autrui à travers la constitution de sa propre mémoire intradiscursive (Moirand 2000). Les numéros 13 et 17 de Semen centrés sur l'analyse de discours et consacrés respectivement aux genres de la presse écrite et à l'argumentation et la prise de position discursive ménagent une place importante à la problématique de la neutralisation de la subjectivité et de la désinscription énonciative. Le présent numéro reprend, prolonge et spécifie certaines des interrogations et propositions émergeant de ces numéros et de différents travaux du champ des sciences du langage. Il se propose de mener la réflexion sur la « texture énonciative » (Moirand 2000) du discours de presse à travers ses différentes réalisations sémiotiques et institutionnelles et sur la responsabilité des instances productrices de ce discours (Charaudeau 1997, Rabatel 2005) . Le cadre théorique de référence est celui d'une linguistique des discours et des textes qui reconnaît comme essentielle le rôle des formations socio-discursives et s'attache à explorer les dimensions dialogiques foncières du discours (Adam, Maingueneau, etc.). La subjectivité généralisée est envisagée comme inhérente à l'activité langagière ; elle ne saurait s'appréhender exclusivement à travers le filtre de ses marques formelles et génériques déclarées mais s'actualise à travers une palette de « simulacres énonciatifs ». Les mutations sémio-technologiques qui affectent l'écriture médiatique − presse en ligne et ses incidences, développement du multimédia, multiplication des hyperstructures (Lugrin 2000 : 69) −, la variété de ses organes et de ses manifestations, les interrelations entre ses formes et ses genres en perpétuelle négociation et redéfinition interviennent de manière décisive dans l'organisation de l'interdiscursivité et les modalités de la prise en charge énonciative. Le numéro analyse un certain nombre de phénomènes d'effacement énonciatif (Vion 2001, Rabatel 2004) dans la presse et réinterroge à cette aune les problématiques de l'argumentation, de la rhétorique, de la construction de la référence, etc

Growing conditioned trees

AbstractFor a Markovian branching particle system in Rd a Palm type distribution on the genealogical trees up to a time horizon t is computed, which generically (i.e. if there are almost surely no multiplicities in the particle positions at time t) can be viewed as a conditional distribution on the trees given that the particle system at time t populates a certain site. The result is obtained in two different ways: by conditioning on the first branching and by means of Kallenberg's method of backward trees

The invasion process of bovine erythrocyte by Babesia divergens: knowledge from an in vitro assay

Babesia divergens is a tick-transmitted apicomplexan parasite for which asexual multiplication in its vertebrate hosts is restricted to erythrocytes. Current knowledge of invasion of these target cells is limited. An efficient in vitro invasion assay was set up to gain access to this information. Parasites prepared from infected RBC, lysed by electroporation, and mixed with bovine RBC in a selected synthetic medium (RPMI 1640 supplemented with calcium) were able to establish subsequent cultures with parasitemia ranging from 6 to 14%. Free parasites remaining in the invasion medium could be eliminated by Percoll gradient and culture could be pursued with the freshly invaded erythrocytes. In this way, the invasion time window could be shortened to obtain a synchronised start of the culture or to study the kinetics of invasion. With this assay we demonstrate that 1) erythrocyte invasion by B. divergens is a rapid process since 70% of the invasion-competent parasites invaded the RBC in less than 45 s; 2) all invasion-competent parasites achieved invasion within 10 min of contact; 3) one erythrocyte could be invaded concomitantly by two merozoites; 4) despite a synchronous start, the parasite population evolved heterogeneously resulting in a progressive loss of synchronisation. Western blot analysis of proteins collected from invasion medium were performed with sera from animals experimentally infected with B. divergens and highlighted several proteins. The dose-dependent, inhibitory effects of these sera on B. divergens invasion suggest that these proteins might be involved in the invasion process. Further investigations are required for their characterisation

Individual heterogeneity in erythrocyte susceptibility to Babesia divergens is a critical factor for the outcome of experimental spleen-intact sheep infections

Susceptibility of sheep erythrocytes to Babesia divergens was investigated in vitro and a high inter-individual variability in their ability to support parasite population development was demonstrated, with some individuals having refractory red blood cells (RBC). As neither changes in growth conditions nor the use of different B. divergens strains influenced the level of susceptibility, the main factor postulated for this variability is the erythrocyte itself. Sheep therefore represent an excellent in vitro model to study the parasite-erythrocyte interaction. In addition, the existence of refractory RBC should help in the identification of the erythrocyte components required for B. divergens development. Experimental infections were carried out on spleen-intact sheep characterized by refractory or fully susceptible erythrocyte types. These differences translated into the successful infection of only those animals with susceptible erythrocytes: infected animals showed no clinical signs, but maintained an asymptomatic persistent infection, as usually observed in the natural bovine host. Sheep therefore represent model organisms that can allow us to study interactions between B. divergens and its vertebrate host at different levels of biological organisation, from the target cell to the intact animal, and represent an experimental infection model of concomitant immunity. Only a low percentage (13%) of the sheep population tested possessed susceptible erythrocytes and the potential role of sheep as a natural host or reservoir of B. divergens is discussed

À la recherche de l'autonomie en Méditerranée postcoloniale : l'exemple du hip-hop algérien

Defence date: 14 June 2018Examining Board: Professor Olivier Roy (EUI) ; Professor Donatella Della Porta ; (EUI) Professor Thomas Hippler (University of Normandie) ; Professor Yves Gonzalez-Quijano (University Lyon 2)Cette thèse propose une analyse du rap algérien à travers une approche pluridisciplinaire mêlant ethnologie et anthropologie culturelle de l'espace social particulier que représentent aujourd'hui les mondes du Hip-Hop en Algérie. Depuis quelques années les études sur la Méditerranée comme entité géographique, sociale et politique, prennent plus d'ampleur, reflétant l’intérêt grandissant pour cette zone dont les peuples ne cessent de proclamer leurs droits et leur place dans le monde. L’Algérie y occupe une place particulière depuis sa guerre de libération nationale, ne cessant de s'affirmer comme une place forte à la frontière de l'Europe et de l'Afrique mais secouée depuis 1962 par des expériences politiques douloureuses et un statut international empreint de sa relation post-coloniale avec la France. C'est cette Méditerranée s'exprimant à plein dans le destin de l’Algérie que cette thèse se propose d'analyser en présentant certains des mondes sociaux les plus actifs au sein de la jeunesse algérienne : les mondes du Hip-Hop. En présentant les spécificités de cette culture urbaine mondiale, relocalisée et réinterprétée dans le contexte algérien, nous proposons une analyse des constructions identitaires et des expressions politiques propres à cette jeunesse. Nous montrons comment ces pratiques culturelles effectives sont le miroir d'une volonté d'agir dans un contexte matériel défavorable, propre au sud de la Méditerranée, tout autant que de ces passé et présent liés au fait colonial qui continuent de s’entremêler. Le Hip-Hop devient alors le parangon d'une mondialisation reprise en main, piratée, réappropriée pour mieux affirmer et construire des zones d'autonomie rejetant à la fois une globalisation injuste et un pouvoir autoritaire liberticide. L'autonomie se joue entre appropriation et détournement : là où la langue reflète avant tout des réalités matérielles de survie

Experimental in vitro transmission of Babesia sp. (EU1) by Ixodes ricinus

Babesia sp. (EU1), first characterized in 2003, has been implicated in human cases of babesiosis in Italy, Austria and Germany. It has been identified in roe deer and in its suspected tick vector, Ixodes ricinus, in several European countries. The aim of the present study was to validate the competence of I. ricinus as a vector of Babesia sp. (EU1) via experimental infections. For this purpose, a parasite strain isolated from roe deer was cloned in sheep erythrocytes. After experimental infections, parasite DNA was successfully amplified by PCR in both eggs and larvae originating from infected I. ricinus females and in the salivary glands of females exposed to Babesia sp. (EU1) as nymphs. We also demonstrate that infected females were able to transmit parasite DNA during a new blood meal. Together with previous epidemiological studies, these results validate I. ricinus as a competent vector for Babesia sp. (EU1)

Babesia and its hosts: adaptation to long-lasting interactions as a way to achieve efficient transmission

Babesia, the causal agent of babesiosis, are tick-borne apicomplexan protozoa. True babesiae (Babesia genus sensu stricto) are biologically characterized by direct development in erythrocytes and by transovarial transmission in the tick. A large number of true Babesia species have been described in various vertebrate and tick hosts. This review presents the genus then discusses specific adaptations of Babesia spp. to their hosts to achieve efficient transmission. The main adaptations lead to long-lasting interactions which result in the induction of two reservoirs: in the vertebrate host during low long-term parasitemia and throughout the life cycle of the tick host as a result of transovarial and transstadial transmission. The molecular bases of these adaptations in vertebrate hosts are partially known but few of the tick-host interaction mechanisms have been elucidated

Babesia sp. EU1 from Roe Deer and Transmission within Ixodes ricinus

We report in vitro culture of zoonotic Babesia sp. EU1 from blood samples of roe deer in France. This study provides evidence of transovarial and transstadial transmission of the parasite within Ixodes ricinus, which suggests that this tick could be a vector and reservoir of EU1