Supershear Rayleigh waves at a soft interface

We report on the experimental observation of waves at a liquid foam surface propagating faster than the bulk shear waves. The existence of such waves has long been debated, but the recent observation of supershear events in a geophysical context has inspired us to search for their existence in a model viscoelastic system. An optimized fast profilometry technique allowed us to observe on a liquid foam surface the waves triggered by the impact of a projectile. At high impact velocity, we show that the expected subshear Rayleigh waves are accompanied by faster surface waves that can be identified as supershear Rayleigh waves.Comment: 4 pages, 4 figures, 2 supplementary video

Viscous cavities

International audienceWe study experimentally the impact of solid spheres in a viscous liquid at moderate Reynolds numbers (Re similar to 5-100). We first determine the drag force by following the slowdown dynamics of projectiles. We then focus on the shape of the free surface: such impacts generate cavities, whose original shape is described and modeled. (C) 2013 American Institute of Physics

L'écologie industrielle et territoriale comme outil pour l'atteinte des objectifs fixés par le Plan d'action 2011-2015 québécois pour la gestion des matières résiduelles

À travers l’étude des flux de matières sur un territoire déterminé, l’écologie industrielle et territoriale est un outil permettant la mise en place d’une approche circulaire des flux, qui se veut plus durable. Cette approche est basée sur le même mode de fonctionnement que les écosystèmes naturels et implique notamment la mise en place de synergies de mutualisation ou de substitution. Face aux nouveaux objectifs et obligations découlant du Plan d’action 2011-2015, qui accompagne la Politique québécoise de gestion des matières résiduelles, l’objectif principal de cet essai est d’exposer comment le concept d’écologie industrielle et territoriale pourrait être utilisé pour atteindre les objectifs et répondre aux obligations règlementaires provinciales. Dans un premier temps, cet essai démontre la pertinence de l’utilisation de l’écologie industrielle et territoriale comme modèle pour la gestion des matières résiduelles au Québec. L’étude de divers cas à succès et la lecture de travaux sur le sujet étayent cette section. Dans un second temps, l’essai propose une méthodologie d’application au sein de la province, en faisant des ponts entre ce qui existe déjà en termes de gestion des matières résiduelles au Québec et en s’inspirant des pratiques déjà mises en oeuvre dans divers cas d’écologie industrielle et territoriale. La production d’une méthodologie d’application ainsi que l’élaboration d’une grille d’évaluation du projet démontrent qu’il est possible d’intégrer le concept d’écologie industrielle et territoriale dans les stratégies municipales pour la gestion des matières résiduelles. Des recommandations sont également formulées et portent sur différents aspects du projet tels que le choix du territoire, l’interaction avec les acteurs, l’importance de la communication, la mise en oeuvre et la pérennité du projet

The spinning ball spiral

International audienceWe discuss the trajectory of a fast revolving solid ball moving in a fluid of comparable density. As the ball slows down owing to drag, its trajectory follows an exponential spiral as long as the rotation speed remains constant: at the characteristic distance L where the ball speed is significantly affected by the drag, the bending of the trajectory increases, surprisingly. Later, the rotation speed decreases, which makes the ball follow a second kind of spiral, also described in the paper. Finally, the use of these highly curved trajectories is shown to be relevant to sports. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft

Aggregation dynamics and identification of aggregation-prone mutants of the von Hippel-Lindau tumor suppressor protein

International audienceQuality control mechanisms promote aggregation and degradation of misfolded proteins. In budding yeast, the human von Hippel-Lindau protein (pVHL, officially known as VHL) is misfolded and forms aggregates. Here, we investigated the aggregation of three pVHL isoforms (pVHL213, pVHL160, pVHL172) in fission yeast. The full-length pVHL213 isoform aggregates in highly dynamic small puncta and in large spherical inclusions, either close to the nucleus or to the cell ends. The large inclusions contain the yeast Hsp104 chaperone. Aggregate clearance is regulated by proteasomal degradation. The pVHL160 isoform forms dense foci and large irregularly shaped aggregates. In silico, prediction of pVHL aggregation propensity identified a key aggregation-promoting region within exon 2. Consistently, the pVHL172 isoform, which lacks exon 2, formed rare reduced inclusions. We studied the aggregation propensity of pVHL variants harbouring missense mutations found in kidney carcinomas. We show that the P86L mutation stimulated small aggregate formation, the P146A mutation increased large inclusion formation, whereas the I151S mutant destabilized pVHL. The prefoldin subunit Pac10 (the human homolog VBP-1 binds to pVHL) is required for pVHL stability. Reduction of soluble functional pVHL might be crucial in VHL-related diseases

Union libre, égalité et bien-être en Suisse

Les naissances de couples non-mariés se diffusent lentement dans la société suisse. Elles remettent en question la place de l’union libre qui depuis son apparition dans les années soixante-dix jouait essentiellement un rôle de prélude au mariage. Les couples non-mariés ayant des enfants montrent une division plus égalitaire des tâches, plus d’autonomie et moins d’attitudes traditionnelles à l’égard de la famille, comparativement aux couples mariés. Paradoxalement, ces couples témoignent d’un moindre bien-être. Cet article s’interroge sur les relations entre statut marital, inégalités au sein du couple et moindre bien-être. Basés sur une exploitation des données Suisses de L'Enquête sur les familles et les générations 2013 (EFG), nos résultats tendent à montrer que les jeunes couples ayant des attitudes égalitaires choisissent plus souvent de rester non-mariés lorsqu’ils ont un enfant. Qu’ils soient mariés ou non, les conjoints ayant des attitudes égalitaires expriment un moindre bien-être que les couples ayant des attitudes traditionnelles. Les raisons de ce moindre bien-être sont liées à la difficulté de concilier vie familiale et vie professionnel, surtout pour les femmes. Les conflits au sein du couple quant à eux, résulteraient plutôt d’une augmentation des affects négatifs

Patient-perceived progression in multiple system atrophy: natural history of quality of life

Health-related quality of life (Hr-QoL) scales provide crucial information on neurodegenerative disease progression, help improving patient care, and constitute a meaningful endpoint for therapeutic research. However, Hr-QoL progression is usually poorly documented, as for multiple system atrophy (MSA), a rare and rapidly progressing alpha-synucleinopathy. This work aimed to describe Hr-QoL progression during the natural course of MSA, explore disparities between patients, and identify informative items using a four-step statistical strategy.We leveraged the data of the French MSA cohort comprising annual assessments with the MSA-QoL questionnaire for more than 500 patients over up to 11 years. The four-step strategy (1) determined the subdimensions of Hr-QoL in MSA; (2) modelled the subdimension trajectories over time, accounting for the risk of death; (3) mapped the sequence of item impairments with disease stages; and (4) identified the most informative items specific to each disease stage.Among the 536 patients included, 50% were women and they were aged on average 65.1 years old at entry. Among them, 63.1% died during the follow-up. Four dimensions were identified. In addition to the original motor, nonmotor, and emotional domains, an oropharyngeal component was highlighted. While the motor and oropharyngeal domains deteriorated rapidly, the nonmotor and emotional aspects were already slightly to moderately impaired at cohort entry and deteriorated slowly over the course of the disease. Impairments were associated with sex, diagnosis subtype, and delay since symptom onset. Except for the emotional domain, each dimension was driven by key identified items.Hr-QoL is a multidimensional concept that deteriorates progressively over the course of MSA and brings essential knowledge for improving patient care. As exemplified with MSA, the thorough description of Hr-QoL using the 4-step original analysis can provide new perspectives on neurodegenerative diseases' management to ultimately deliver better support focused on the patient's perspective

Validation of an LC-MS/MS Method Using Solid-Phase Extraction for the Quantification of 1-84 Parathyroid Hormone: Toward a Candidate Reference Measurement Procedure.

peer reviewed[en] BACKGROUND: Parathyroid hormone (PTH) measurement is important for patients with disorders of calcium metabolism, including those needing bone-turnover monitoring due to chronic kidney disease-mineral bone disorder. There are currently 2 generations of PTH immunoassays on the market, both having cross-reactivity issues and lacking standardization. Therefore, we developed an LC-MS/MS higher-order method for PTH analysis. METHODS: The method was calibrated against the international standard for 1-84 PTH (WHO 95/646). Antibody-free sample preparation with the addition of an isotope-labeled internal standard was performed by solid-phase extraction. Extracts were analyzed by LC-MS/MS. EDTA-K2 plasma was used throughout the development and validation. Bias and uncertainty sources were tested according to ISO 15193. Clinical Laboratory Standards Institute guidelines and reference measurement procedures were consulted for the design of the validation. Patient samples and external quality controls were compared between LC-MS/MS and 2 third-generation immunoassays. RESULTS: The method was validated for 1-84 PTH from 5.7 to 872.6 pg/mL. The interassay imprecision was between 1.2% and 3.9%, and the accuracy ranged from 96.2% to 103.2%. The measurement uncertainty was <5.6%. The comparison between LC-MS/MS and the immunoassays showed a proportional bias but moderate to substantial correlation between methods. CONCLUSIONS: This LC-MS/MS method, which is independent of antibodies, is suitable for a wide range of PTH concentrations. The obtained analytical performance specifications demonstrate that development of a reference measurement procedure will be possible once a higher order reference standard is available