Self-propulsion and crossing statistics under random initial conditions

We investigate the crossing of an energy barrier by a self-propelled particle described by a Rayleigh friction term. We reveal the existence of a sharp transition in the external force field whereby the amplitude dramatically increases. This corresponds to a saddle point transition in the velocity flow phase space, as would be expected for any type of repulsive force field. We use this approach to rationalize the results obtained by Eddi \emph{et al.} [\emph{Phys. Rev. Lett.} \textbf{102}, 240401 (2009)] who studied the interaction between a drop propelled by its accompanying wave field and a submarine obstacle. This wave particle entity can overcome potential barrier, suggesting the existence of a "macroscopic tunneling effect". We show that the effect of self-propulsion is sufficiently strong to generate crossing of the high energy barrier. By assuming a random distribution of initial angles, we define a probability distribution to cross the potential barrier that matches with the data of Eddi \emph{et al.}. This probability is similar to the one encountered in statistical physics for Hamiltonian systems \textit{i.e.} a Boltzmann exponential law.Comment: 7 pages, 4 figure

Modelo dominante y variaciones nacionales en el diseño de políticas de investigación en favor de la innovación tecnológica: una aproximación comparativa de los dispositivos de apoyo a la nanociencia y nanotecnología en Argentina y Francia

El objetivo de este texto es cuestionar el carácter global del proceso que conduce a la puesta en marcha de políticas de investigación en favor de la innovación tecnológica. Con dicha finalidad, el artículo realiza un análisis contrastivo de las políticas públicas en el campo de la nanociencia y nanotecnología en Argentina y Francia. Esta comparación muestra que, si bien las agendas y los instrumentos de políticas públicas de ciencia y tecnología se han globalizado, su puesta en marcha está fuertemente modelada por el contexto local en el que se desarrollan.Fil: Hubert, Matthieu Pierre. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes; Argentin

The Use of Foreign Examples in Research Policy: Public Funding for Nanoscience and Nanotechnology in France

This article examines the influence of major international paradigms on nanoscience and nanotechnology funding policies (nanoS & T) pursued in France during the 2000s (1999–2013). It is concerned with how foreign examples become exemplary (in the sense of “exemplar” as used by Kuhn 1990) to the extent of being regarded as public policy solutions. Using extensive qualitative research in the field of nanoS & T, the article shows that the paradigmatic value of foreign examples derives from the processes of “editing” (Sahlin and Wedlin 2008), i.e., de-contextualization and re-contextualization which establishes their relevance for certain dimensions of science policy. It highlights three key approaches to this editing work—one which creates an example of a prototype for public policy, one that lists comparable examples more systematically to define a concept, and finally one which borrows from management techniques—and identifies the key actors in the development of national programmes and the creation of local innovation clusters in nanoS & T.Fil: Louvel, Séverine. Domaine Universitaire; Francia. University of California at Los Angeles; Estados UnidosFil: Hubert, Matthieu Pierre. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencias Sociales; Argentin

Cotranscription and intergenic splicing of the PPARG and TSEN2 genes in cattle

BACKGROUND: Intergenic splicing resulting in the combination of mRNAs sequences from distinct genes is a newly identified mechanism likely to contribute to protein diversity. Few cases have been described, most of them involving neighboring genes and thus suggesting a cotranscription event presumably due to transcriptional termination bypass. RESULTS: We identified bovine chimeric transcripts resulting from cotranscription and intergenic splicing of two neighboring genes, PPARG and TSEN2. These two genes encode the Peroxisome Proliferator Activated Receptors γ1 and γ2 and the tRNA Splicing Endonuclease 2 homolog and are situated in the same orientation about 50 kb apart on bovine chromosome 22q24. Their relative position is conserved in human and mouse. We identified two types of chimeric transcripts containing all but the last exon of the PPARG gene followed by all but the first exon of the TSEN2 gene. The two chimers differ by the presence/absence of an intermediate exon resulting from transcription of a LINE L2 sequence situated between the two genes. Both transcripts use canonical splice sites for all exons coming from both genes, as well as for the LINE L2 sequence. One of these transcripts harbors a premature STOP codon and the other encodes a putative chimeric protein combining most of the PPARγ protein and the entire TSEN2 protein, but we could not establish the existence of this protein. CONCLUSION: By showing that both individual and chimeric transcripts are transcribed from PPARG and TSEN2, we demonstrated regulation of transcription termination. Further, the existence and functionality of a chimeric protein harboring active motifs that are a priori unrelated is hypothesized

FM-AFM with hanging fiber probe for the study of liquid / liquid interfaces

This article describes how an FM-AFM using a hanging fiber force probe made from a quartz tuning fork provides local measurements on liquid-liquid interfaces. After detailing the manufacture and calibration of the force probe, we provide evidence that this AFM is suitable for quantitative measurements at the interface between two liquids. The repeatability of the measurements allows a PDMS / water moving interface to be monitored over several hours : the evaporation of a water droplet immersed in PDMS is observed, and its interfacial tension evolution over time is measured. Deformation of the interface is also observed. These capabilities, and preliminary results on the interface between two immiscible liquids, pave the way for interface manipulation and study of complex fluid-fluid interfaces

Overload wave-memory induces amnesia of a self-propelled particle

Information storage, for short "memory", is a key element of autonomous, out-of-equilibrium dynamics, in particular in biological entities. In synthetic active matter, however, the implementation of internal memory in agents is often limited or even absent. As a consequence, most of the investigations in the field of active matter had no choice but to ignore the influence of memory on the dynamics of these systems. We take here the opportunity to explore this question by leveraging one of the very few experimental physical system in which memory can be described in terms of a single and most importantly tunable scalar quantity. Here we consider a particle propelled at a fluid interface by self-generated stationary waves. The amount of souvenirs stored in the wave-memory field can be tuned, allowing for a throughout investigation of the properties of this memory-driven dynamics. We show numerically and experimentally that the accumulation of information in the wave field induces the loss of long-range time correlations. The dynamics can then be described by a memory-less process. We rationalize the resulting statistical behavior by defining an effective temperature for the particle dynamics and by evidencing a minimization principle for the wave field

« Comme un enfant et un fou » : Henri Seyrig dans la Grande Guerre

Écrivant dix ans après la guerre, Henri Seyrig estimait qu’il l’avait vécue tel « un enfant et un fou », soulignant le manque de maturité ou de lucidité dont, selon lui, il avait fait preuve face aux événements historiques sans précédent auxquels, comme des millions d’autres, il avait été confronté . Comprendre ce qu’a pu représenter la Grande Guerre dans son existence revient à modifier quelque peu le sens de la relation fréquemment posée entre guerre et individu. Alors que depuis les années..

Piloter la recherche? Les effets des politiques de soutien aux nanosciences sur les stratégies scientifiques des chercheurs

Le domaine des nanosciences est devenu une priorité de politique scientifique dans la plupart des pays développés et émergents. A ce titre, il constitue un terrain favorable pour s´interroger sur les effets de la programmation de la recherche sur les stratégies scientifiques des chercheurs et l´organisation des équipes concernées. La première partie de l´article décrit l´historique des programmes de financement de la recherche en nanosciences en France. La seconde partie analyse les discours de chercheurs en nanosciences de la région parisienne, concernant les transformations liées à ce foisonnement de programmes de recherche. L´enquête menée montre les effets de la programmation sur la recherche menée au sein des laboratoires : une recherche moins risquée, qui présente davantage de résultats préliminaires garantissant sa fécondité future ; une recherche dont l´horizon temporel est fixé a priori (et/ou est de plus court terme) ; et, enfin, une recherche bénéficiant moins de la capacité de redistribution financière d´un laboratoire.Fil: Hubert, Matthieu Pierre. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Piloter la recherche? Les effets des politiques de soutien aux nanosciences sur les stratégies scientifiques des chercheurs

Le domaine des nanosciences est devenu une priorité de politique scientifique dans la plupart des pays développés et émergents. A ce titre, il constitue un terrain favorable pour s´interroger sur les effets de la programmation de la recherche sur les stratégies scientifiques des chercheurs et l´organisation des équipes concernées. La première partie de l´article décrit l´historique des programmes de financement de la recherche en nanosciences en France. La seconde partie analyse les discours de chercheurs en nanosciences de la région parisienne, concernant les transformations liées à ce foisonnement de programmes de recherche. L´enquête menée montre les effets de la programmation sur la recherche menée au sein des laboratoires : une recherche moins risquée, qui présente davantage de résultats préliminaires garantissant sa fécondité future ; une recherche dont l´horizon temporel est fixé a priori (et/ou est de plus court terme) ; et, enfin, une recherche bénéficiant moins de la capacité de redistribution financière d´un laboratoire.Fil: Hubert, Matthieu Pierre. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Des hellénistes en guerre

L’étude du parcours militaire des membres de l’École française d’Athènes durant la Grande Guerre met en évidence certains particularismes. En effet, ceux-ci servent préférentiellement sur le front d’Orient où, promus officiers, ils occupent des emplois liés à la propagande, l’interprétariat ou le renseignement. Ce parcours spécifique résulte à la fois de démarches individuelles de la part des intéressés et de la reconnaissance par les autorités militaires des compétences que ces personnes détenaient en raison de leur formation, lesquelles les rendirent particulièrement propres à remplir les missions qui leur furent confiées.Hellenists at war. The atypical service of members of the French school of Athens during the First World War.  The study of the military service of the members of the French School of Athens during the Great War reveals some peculiarities. Indeed, they served preferentially in the East, where as officers, they had jobs related to propaganda, interpretation or intelligence. This specific service resulted from both individual efforts by those interested and recognition by military authorities of the capabilities held by these people because of their training, which made them particularly suitable for accomplishing the missions they were assigned