Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

Améliorer le pilotage des prélèvements d'eau pour l'irrigation : moyens et méthodes

Fiche techniqueLa gestion des prélèvements pour l'irrigation reste conflictuelle chaque été dans de nombreux départements. Le recensement des acteurs en présence et de leur rôle fait apparaître comment sont représentés les différents usages de l'eau lors des crises ; la situation est différente et évolue pour la gestion à moyen terme. Une analyse de 20 dispositifs de gestion volumétrique montre comment se fait actuellement la mobilisation des informations ; des expériences en cours explorent comment créer de l'information partagée pour dépasser la gestion de crise

Radial Distribution of Mass Transfer and Wall Shear Instantaneous Rates in Couette-Taylor Flow

International audienc

Activités d'éveil scientifiques à l'école élémentaire. 5 : Démarches pédagogiques en initiation physique et technologique

Dans la série des RECHERCHES PÉDAGOGIQUES sur les activités d'éveil scientifiques à l'école élémentaire, cette publication marque une orientation nouvelle. Il ne s'agit plus ici de plaider pour l'introduction d'activités scientifiques de type physico-technologique à l'école : le fascicule n° 74 et les publications d'éditeurs privés ont suffisamment montré la possibilité et l'intérêt d'une telle initiation en développant de nombreux thèmes d'étude. L'ambition des auteurs a été d'ab.order quelques questions fondamentales touchant les démarches pédagogiques. Ces questions sont apparues de manière particulièrement aiguë dans le domaine des sciences physiques. Mais les lecteurs verront facilement que les problèmes pédagogiques ainsi visés concernent les autres disciplines scientifiques et sont ceux de tout pédagogue qui assume la responsabilité d'une classe pendant une année scolaire entière. Dans une perspective de construction structurée du savoir, une revue des problèmes posés par les représentations, les moyens de les connaître et de les transformer, occupe en première partie une place très importante de ce numéro. Ensuite c'est avant tout en pensant à cette responsabilité des ¡instituteurs que la recherche s'est intéressée à l'organisation de l'année scolaire : tableau des objectifs, planning des sujets d'étude. Mais les réflexions à ce sujet seraient de peu de valeur pour une initiation scientifique si on méconnaissait les voies qui permettent de passer de quelques acquis empiriques ponctuels à un savoir conceptuel organisé, du tâtonnement répété à des méthodes d'investigation. Les premiers éléments apportés ici — discutables et à discuter — sont une esquisse du grand travail de recueil, de comparaison, et de synthèse qu'il serait nécessaire de poursuivre à ce sujet.128 pages, figures, tableaux, 8 références bibliographique

Ribosome recycling depends on a mechanistic link between the FeS cluster domain and a conformational switch of the twin-ATPase ABCE1

Despite some appealing similarities of protein synthesis across all phyla of life, the final phase of mRNA translation has yet to be captured. Here, we reveal the ancestral role and mechanistic principles of the newly identified twin-ATPase ABCE1 in ribosome recycling. We demonstrate that the unique iron-sulfur cluster domain and an ATP-dependent conformational switch of ABCE1 are essential both for ribosome binding and recycling. By direct (1∶1) interaction, the peptide release factor aRF1 is shown to synergistically promote ABCE1 function in posttermination ribosome recycling. Upon ATP binding, ABCE1 undergoes a conformational switch from an open to a closed ATP-occluded state, which drives ribosome dissociation as well as the disengagement of aRF1. ATP hydrolysis is not required for a single round of ribosome splitting but for ABCE1 release from the 30S subunit to reenter a new cycle. These results provide a mechanistic understanding of final phases in mRNA translation