Experimental study of the transport properties of rough self-affine fractures

An experimental study of the transport properties of fluid-saturated joints composed of two complementary rough fracture surfaces, translated with respect to each other and brought in contact, is reported. Quantitative roughness measurements on different fractured granite samples show that the surfaces have a self-affine geometry from which the dependence of the mean aperture on the relative displacement of fracture surfaces kept in contact can be predicted. Variations of the hydraulic and electrical conductances of the joint are measured as functions of its mean aperture. A simple parallel plane model accounts for the global trend of the measurements, but significant deviations are observed when a relative lateral displacement of the surfaces is introduced. A theoretical analysis of their origin shows that they are due both to the randomness of the aperture field and to a nonzero local slope of the surface near the injection hole; the corresponding conductivity fluctuation amplitudes have power law and linear variations with the lateral displacement, and are enhanced by the radial injection geometry

QMEAN server for protein model quality estimation

Model quality estimation is an essential component of protein structure prediction, since ultimately the accuracy of a model determines its usefulness for specific applications. Usually, in the course of protein structure prediction a set of alternative models is produced, from which subsequently the most accurate model has to be selected. The QMEAN server provides access to two scoring functions successfully tested at the eighth round of the community-wide blind test experiment CASP. The user can choose between the composite scoring function QMEAN, which derives a quality estimate on the basis of the geometrical analysis of single models, and the clustering-based scoring function QMEANclust which calculates a global and local quality estimate based on a weighted all-against-all comparison of the models from the ensemble provided by the user. The web server performs a ranking of the input models and highlights potentially problematic regions for each model. The QMEAN server is available at http://swissmodel.expasy.org/qmean

Research needs in allergy: an EAACI position paper, in collaboration with EFA

Abstract In less than half a century, allergy, originally perceived as a rare disease, has become a major public health threat, today affecting the lives of more than 60 million people in Europe, and probably close to one billion worldwide, thereby heavily impacting the budgets of public health systems. More disturbingly, its prevalence and impact are on the rise, a development that has been associated with environmental and lifestyle changes accompanying the continuous process of urbanization and globalization. Therefore, there is an urgent need to prioritize and concert research efforts in the field of allergy, in order to achieve sustainable results on prevention, diagnosis and treatment of this most prevalent chronic disease of the 21 st century. The European Academy of Allergy and Clinical Immunology (EAACI) is the leading professional organization in the field of allergy, promoting excellence in clinical care, education, training and basic and translational research, all with the ultimate goal of improving the health of allergic patients. The European Federation of Allergy and Airways Diseases Patients' Associations (EFA) is a non-profit network of allergy, asthma and Chronic Obstructive Pulmonary Disorder (COPD) patients' organizations. In support of their missions, the present EAACI Position Paper, in collaboration with EFA, highlights the most important research needs in the field of allergy to serve as key recommendations for future research funding at the national and European levels. Although allergies may involve almost every organ of the body and an array of diverse external factors act as triggers, there are several common themes that need to be prioritized in research efforts. As in many other chronic diseases, effective prevention, curative treatment and accurate, rapid diagnosis represent major unmet needs. Detailed phenotyping/endotyping stands out as widely required in order to arrange or re-categorize clinical syndromes into more coherent, uniform and treatment-responsive groups. Research efforts to unveil the basic pathophysiologic pathways and mechanisms, thus leading to the comprehension and resolution of the pathophysiologic complexity of allergies will allow for the design of novel patient-oriented diagnostic and treatment protocols. Several allergic diseases require well-controlled epidemiological description and surveillance, using disease registries, pharmacoeconomic evaluation, as well as large biobanks. Additionally, there is a need for extensive studies to bring promising new biotechnological innovations, such as biological agents, vaccines of modified allergen molecules and engineered components for allergy diagnosis, closer to clinical practice. Finally, particular attention should be paid to the difficult-to-manage, precarious and costly severe disease forms and/or exacerbations. Nonetheless, currently arising treatments, mainly in the fields of immunotherapy and biologicals, hold great promise for targeted and causal management of allergic conditions. Active involvement of all stakeholders, including Patient Organizations and policy makers are necessary to achieve the aims emphasized herein

Etude experimentale d'un systeme hors d'equilibre fortement non-lineaire: fronts cellulaires en solidification directionnelle d'un alliage dilue (CBr_4)

SIGLEINIST T 74009 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Bubble Rupture in a Vibrated Liquid Under Microgravity

International audienceThe response of an air bubble surrounded by a liquid in a sealed cell submitted to vibrations was investigated experimentally under microgravity conditions and compared to experiments under normal gravity conditions. As in normal gravity [1], it was observed that the bubble split into smaller parts when the acceleration of the vibrations reached a threshold. This threshold in microgravity is substantially smaller than that in normal gravity. Experimental results are presented in terms of an acceleration based Bond number which has been found to characterize the bubble behaviour in the laboratory experiments [1]

Water drops in a denser miscible fluid: coalescence, drop shape and penetration depth.

International audienceWhen delicately put in contact with the surface of a denser miscible fluid (as salt-water or glycerin-water mixture), a water drop undergoes a quick coalescence. It then enters the surrounding fluid with a resulting toric shape and a rather high velocity of fall, up to about 20 cm/s. With both effects of buoyancy and viscosity dissipation, the drop progressively slows down until it totally stops and starts rising back. From this inversion of the motion, the toric shape of the drop becomes unstable and gives rise to a succession of destabilizations. We have studied the initial velocity of the drop and its penetration depth, as well as their dependences with the properties of the surrounding fluid (viscosity, surface tension, density difference). In particular, our results reveal that, contrary to a model previously proposed, the initial velocity cannot be simply interpreted as a direct conversion from surface energy to kinetic energy. It seems indeed strongly dependent to the exact nature of the coalescence

Séparation de particules microniques par focalisation hydrodynamique

La séparation de particules de taille micronique par la technique dite de SPLITT a mis en évidence des effets de migrations transverses non spécifiques, qui limitent l'efficacité de cette séparation dans le cas d'un mélange de plusieurs espèces. Des expériences en micropesanteur ont montré le rôle important joué par la diffusion hydrodynamique induite par cisaillement dans cette migration anormale. Une nouvelle cellule a donc été mise au point : les particules sont injectées au centre du canal dans l'épaisseur de la cellule et peuvent être focalisées dans n'importe quelle position dans l'épaisseur. La focalisation hydrodynamique ainsi contrôlée permet d'éloigner les particules des parois, où le cisaillement est maximal, afin de minimiser les effets des forces de portance et de diffusion. Les premiers tests de séparation binaire réalisés avec cette cellule de focalisation sont très encourageants puisqu'ils montrent une augmentation notable de l'efficacité, en termes de pureté des échantillons, comparée à celle obtenue avec la cellule de SPLITT