493 research outputs found
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 matiÚres résiduelles
Ă travers lâĂ©tude des flux de matiĂšres sur un territoire dĂ©terminĂ©, lâĂ©cologie industrielle et territoriale est un outil permettant la mise en place dâune approche circulaire des flux, qui se veut plus durable. Cette approche est basĂ©e sur le mĂȘme mode de fonctionnement que les Ă©cosystĂšmes naturels et implique notamment la mise en place de synergies de mutualisation ou de substitution. Face aux nouveaux objectifs et obligations dĂ©coulant du Plan dâaction 2011-2015, qui accompagne la Politique quĂ©bĂ©coise de gestion des matiĂšres rĂ©siduelles, lâobjectif principal de cet essai est dâexposer comment le concept dâĂ©cologie industrielle et territoriale pourrait ĂȘtre utilisĂ© pour atteindre les objectifs et rĂ©pondre aux obligations rĂšglementaires provinciales. Dans un premier temps, cet essai dĂ©montre la pertinence de lâutilisation de lâĂ©cologie industrielle et territoriale comme modĂšle pour la gestion des matiĂšres rĂ©siduelles au QuĂ©bec. LâĂ©tude de divers cas Ă succĂšs et la lecture de travaux sur le sujet Ă©tayent cette section. Dans un second temps, lâessai propose une mĂ©thodologie dâapplication au sein de la province, en faisant des ponts entre ce qui existe dĂ©jĂ en termes de gestion des matiĂšres rĂ©siduelles au QuĂ©bec et en sâinspirant des pratiques dĂ©jĂ mises en oeuvre dans divers cas dâĂ©cologie industrielle et territoriale. La production dâune mĂ©thodologie dâapplication ainsi que lâĂ©laboration dâune grille dâĂ©valuation du projet dĂ©montrent quâil est possible dâintĂ©grer le concept dâĂ©cologie industrielle et territoriale dans les stratĂ©gies municipales pour la gestion des matiĂšres rĂ©siduelles. Des recommandations sont Ă©galement formulĂ©es et portent sur diffĂ©rents aspects du projet tels que le choix du territoire, lâinteraction avec les acteurs, lâimportance de la communication, la mise en oeuvre et la pĂ©rennitĂ© 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, Ă©galitĂ© et bien-ĂȘtre en Suisse
Les naissances de couples non-mariĂ©s se diffusent lentement dans la sociĂ©tĂ© suisse. Elles remettent en question la place de lâunion libre qui depuis son apparition dans les annĂ©es soixante-dix jouait essentiellement un rĂŽle de prĂ©lude au mariage. Les couples non-mariĂ©s ayant des enfants montrent une division plus Ă©galitaire des tĂąches, plus dâautonomie et moins dâattitudes traditionnelles Ă lâĂ©gard de la famille, comparativement aux couples mariĂ©s. Paradoxalement, ces couples tĂ©moignent dâun moindre bien-ĂȘtre. Cet article sâinterroge sur les relations entre statut marital,
inĂ©galitĂ©s au sein du couple et moindre bien-ĂȘtre. BasĂ©s sur une exploitation des donnĂ©es Suisses de L'EnquĂȘte sur les familles et les gĂ©nĂ©rations 2013 (EFG), nos rĂ©sultats tendent Ă montrer que les jeunes couples ayant des attitudes Ă©galitaires choisissent plus souvent de rester non-mariĂ©s lorsquâils ont un enfant. Quâils soient mariĂ©s ou non, les conjoints ayant des attitudes Ă©galitaires expriment un moindre bien-ĂȘtre que les couples ayant des attitudes traditionnelles. Les raisons de ce moindre bien-ĂȘtre sont liĂ©es Ă la difficultĂ© de concilier vie familiale et vie professionnel, surtout
pour les femmes. Les conflits au sein du couple quant Ă eux, rĂ©sulteraient plutĂŽt dâune augmentation des affects nĂ©gatifs
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 872.6â
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
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