Rolling and ageing in T-ramp soft adhesion

Immediately before adsorption to a horizontal substrate, sinking polymer-coated colloids can undergo a complex sequence of landing, jumping, crawling and rolling events. Using video tracking we studied the soft adhesion to a horizontal flat plate of micron-size colloids coated by a controlled molar fraction $f$ of the polymer PLL-g-PNIPAM which is temperature sensitive. We ramp the temperature from below to above $T_c=32\pm 1^{\circ}$C, at which the PNIPAM polymer undergoes a transition triggering attractive interaction between microparticles and surface. The adsorption rate, the effective in-plane ($x-y$) diffusion constant and the average residence time distribution over $z$ were extracted from the Brownian motion records during last seconds before immobilisation. Experimental data are understood within a rate-equations based model that includes ageing effects and includes three populations: the untethered, the rolling and the arrested colloids. We show that pre-adsorption dynamics casts analyze a characteristic scaling function $\alpha (f)$ proportional to the number of available PNIPAM patches met by soft contact during Brownian rolling. In particular, the increase of in-plane diffusivity with increasing $f$ is understood: the stickiest particles have the shortest rolling regime prior to arrest, so that their motion is dominated by untethered phase

An Intuitive Automated Modelling Interface for Systems Biology

We introduce a natural language interface for building stochastic pi calculus models of biological systems. In this language, complex constructs describing biochemical events are built from basic primitives of association, dissociation and transformation. This language thus allows us to model biochemical systems modularly by describing their dynamics in a narrative-style language, while making amendments, refinements and extensions on the models easy. We demonstrate the language on a model of Fc-gamma receptor phosphorylation during phagocytosis. We provide a tool implementation of the translation into a stochastic pi calculus language, Microsoft Research's SPiM

Academic workforce in France and the UK in historical perspectives

This historical exploration of the development of the academic workforce in the UK and France was triggered by the observation of significant similarities in contemporary debates on casualisation, and segmentation despite their distinctive HE systems. We develop a quantitative history of academic staff to understand why the differences in the two HE systems are not as significant in respect to labour market and working conditions. The new data show that connected processes of casualisation, professional segmentation, and sectorial differentiation are used to manage tensions between massification and staff recruitment in both countries, in a context of declining and increasingly unequal distribution of resources, producing inequalities within institutions, as within the profession itself. The reorganisation of the academic workforce during three periods of growth of HE systems under traditional, Fordist and managerial influences has incrementally produced three groups of permanent, casualised, and precarised staff and a dual academic labour market

Avalanche et territoires touristiques de montagne, pour une prise en compte des facteurs actifs de vulnérabilité propres aux modalités de réponse au problème « risque ».

Les risques qualifiés de « naturels » sont majoritairement appréhendés sous l'angle de la menace externe. Cette conception du risque est associée à une gestion de type « aléa-centrée ». Elle amalgame parfois le traitement de l'aléa (phénomènes naturels) avec ce que recouvre plus largement la gestion du risque. Nous proposons ici, sur la base d'une recherche menée dans le champ du risque d'avalanche, d'endogénéiser l'approche du risque, en mettant l'accent sur les facteurs actifs de vulnérabilité propres aux modalités de gestion

SQUARE: Scalable Quorum-Based Atomic Memory with Local Reconfiguration

International audienceInternet applications require more and more resources to satisfy the unpredictable clients needs. Specifically, such applications must ensure quality of service despite bursts of load. Distributed dynamic self-organized systems present an inherent adaptiveness that can face unpredictable bursts of load. Nevertheless quality of service, and more particularly data consistency, remains hardly achievable in such systems since participants (i.e., nodes) can crash, leave, and join the system at arbitrary time. The atomic consistency guarantees that any read operation returns the last written value of a data and is generalizable to data composition. To guarantee atomicity in message-passing model, mutually intersecting sets (a.k.a.quorums) of nodes are used. The solution presented here, namely SQUARE, provides scalability, load-balancing, fault-tolerance, and self-adaptiveness, while ensuring atomic consistency. We specify our solution, prove it correct and analyse it through simulations. \\ Les applications utilisées via internet nécessitent de plus en plus de ressources afin de satisfaire les besoins imprévisibles des clients. De telles applications doivent assurer une certaine qualité de service en dépit des pics de charge. Les systèmes distribués dynamiques capable de s'auto-organiser ont une capacité intrinsèque pour supporter ces pics de charge imprévisibles. Cependant, la qualité de service et plus particulièrement la cohérence des données reste très difficile à assurer dans de tels systèmes. En effet, les participants, ou noeuds, peuvent rejoindre, quitter le système, et tomber en panne de façon arbitraire. La cohérence atomique assure que toute lecture renvoie la dernière valeur écrite et la relation de composition la préserve. Afin de garantir l'atomicité dans un modèle à passage de message, des ensembles de noeuds s'intersectant mutuellement (les quorums) sont utilisés. La solution présentée ici, appelée SQUARE, est exploitable à grande échelle, permet de balancer la charge, tolère les pannes et s'auto-adapte tout en assurant l'atomicité. Nous spécifions la solution, la prouvons correcte et la simulons pour en analyser les performances

The source of laterally transferred genes in bacterial genomes

BACKGROUND: Laterally transferred genes have often been identified on the basis of compositional features that distinguish them from ancestral genes in the genome. These genes are usually A+T-rich, arguing either that there is a bias towards acquiring genes from donor organisms having low G+C contents or that genes acquired from organisms of similar genomic base compositions go undetected in these analyses. RESULTS: By examining the genome contents of closely related, fully sequenced bacteria, we uncovered genes confined to a single genome and examined the sequence features of these acquired genes. The analysis shows that few transfer events are overlooked by compositional analyses. Most observed lateral gene transfers do not correspond to free exchange of regular genes among bacterial genomes, but more probably represent the constituents of phages or other selfish elements. CONCLUSIONS: Although bacteria tend to acquire large amounts of DNA, the origin of these genes remains obscure. We have shown that contrary to what is often supposed, their composition cannot be explained by a previous genomic context. In contrast, these genes fit the description of recently described genes in lambdoid phages, named 'morons'. Therefore, results from genome content and compositional approaches to detect lateral transfers should not be cited as evidence for genetic exchange between distantly related bacteria

A new setup for giant soap films characterization

Artists, using an empirical knowledge, manage to generate and play with giant soap films and bubbles. Until now, scientific studies of soap films generated at a controlled velocity and without any feeding from the top, studied films of a few square centimeters. The present work aims to present a new setup to generate and characterize giant soap films (2~m $\times$ 0.7~m). Our setup is enclosed in a humidity-controlled box of 2.2~m high, 1~m long and 0.75~m large. Soap films are entrained by a fishing line withdrawn out of a bubbling solution at various velocities. We measure the maximum height of the generated soap films, as well as their lifetime, thanks to an automatic detection. This is allowed by light-sensitive resistors collecting the light reflected on the soap films and ensures robust statistical measurements. In the meantime, thickness measurements are performed with a UV-VIS-spectrometer, allowing us to map the soap films thickness over time

Gouvernance touristique des grandes stations et durabilité. Une lecture en termes de proximité

Les stations de sport d’hiver sont aujourd’hui confrontées à de nombreuses incertitudes tant structurelles que conjoncturelles. Les modalités de leur gestion constituent un axe important de réflexion dans la plupart des stations, notamment les grandes, cœur de notre propos. En effet, la loi Montagne a conféré aux communes la responsabilité du pilotage des stations ; une gestion qu’elle assume ou bien délègue à des opérateurs privés, par l’intermédiaire de services publics. Ces choix conduisent à des formes variées de relations entre acteurs privés et publics. Cette communication se propose de qualifier les modes de relations entre acteurs des stations, en mobilisant le cadre analytique d’économie de la proximité. Ainsi, les articulations entre proximités organisationnelle et cognitive sont très variées au sein des stations et peuvent témoigner de situations conflictuelles, entre des acteurs relevant des sphères privées comme publiques. Afin de lever les blocages, l’enjeu est de comprendre comment les positions des différents groupes se sont construites, comment la gouvernance s’est donc établie au sein des stations. Une telle compréhension permet d’encourager des formes de négociation et de créer les conditions de scènes locales de discussion sur le devenir des stations. Les stations des Arcs, de Val d’Isère en Savoie illustreront la diversité des modalités d’articulation entre proximités organisationnelle et cognitive, et ce dans des contextes territoriaux variés.  The winter sports resorts are confronted today with many uncertainties as well structural as of the economic situation. Methods of their management constitute an important axis of reflexion in the majority of the ski resorts, especially the most important, our goal in this paper. Indeed, the Mountain law conferred on the communes the responsibility for the piloting of the stations ; a management which it assumes or delegates to private operators, via public services. These choices lead to forms varied of relations between private and public actors. This communication proposes to qualify the modes of relations between actors of the stations, by mobilizing the analytical framework of economy of the proximity. Thus, the articulations between proximities organisational and cognitive are very varied within the stations and can testify to conflict situations, between actors concerning spheres deprived like public. In order to raise blockings, the stake is to include/understand how the positions of the various groups were built, how the governance was thus established within the stations. Such a comprehension makes it possible to encourage forms of negotiation and to create the conditions of local scenes of discussion on becoming to it stations. The stations of the Arcs, of Val d’Isère in Savoy will illustrate the diversity of the methods of articulation between proximities organisational and cognitive, in varied territorial contexts

How antifoams act: a microgravity study

peer reviewe

Transcription variants of SLA-7, a swine non classical MHC class I gene

In pig, very little information is available on the non classical class I (Ib) genes of the Major Histocompatibility Complex (MHC) i.e. SLA-6, -7 and -8. Our aim was to focus on the transcription pattern of the SLA-7 gene. RT-PCR experiments were carried out with SLA-7 specific primers targeting either the full coding sequence (CDS) from exon 1 to the 3 prime untranslated region (3UTR) or a partial CDS from exon 4 to the 3UTR. We show that the SLA-7 gene expresses a full length transcript not yet identified that refines annotation of the gene with eight exons instead of seven as initially described from the existing RefSeq RNA. These two RNAs encode molecules that differ in cytoplasmic tail length. In this study, another SLA-7 transcript variant was characterized, which encodes a protein with a shorter alpha 3 domain, as a consequence of a splicing site within exon 4. Surprisingly, a cryptic non canonical GA-AG splicing site is used to generate this transcript variant. An additional SLA-7 variant was also identified in the 3UTR with a splicing site occurring 31 nucleotides downstream to the stop codon. In conclusion, the pig SLA-7 MHC class Ib gene presents a complex transcription pattern with two transcripts encoding various molecules and transcripts that do not alter the CDS and may be subject to post-transcriptional regulation