Characterization of the glass transition in vitreous silica by temperature scanning small-angle X-ray scattering

The temperature dependence of the x-ray scattering in the region below the first sharp diffraction peak was measured for silica glasses with low and high OH content (GE-124 and Corning 7980). Data were obtained upon scanning the temperature at 10, 40 and 80 K/min between 400 K and 1820 K. The measurements resolve, for the first time, the hysteresis between heating and cooling through the glass transition for silica glass, and the data have a better signal to noise ratio than previous light scattering and differential thermal analysis data. For the glass with the higher hydroxyl concentration the glass transition is broader and at a lower temperature. Fits of the data to the Adam-Gibbs-Fulcher equation provide updated kinetic parameters for this very strong glass. The temperature derivative of the observed X-ray scattering matches that of light scattering to within 14%.Comment: EurophysicsLetters, in pres

ATP-sensitive K channels in heart muscle Spare channels

AbstractWe show that ATP-sensitive K+ channels of excised inside-out membrane patches of rat ventricular myocytes show considerable variation in their sensitivity to ATP. In 102 different membrane patches IC50 values ranged from 9 to 580 μM ATP and Hill coefficient from 1% to 6.41% of patches showed openings of ATP-sensitive K+ channels in the presence of 1 mM ATP. These results considerably widen the range of internal ATP concentrations over which one might expect activation of the ATP-sensitive K+ current in cardiac myocytes

Birds as bio-indicators and as tools to evaluate restoration measures

Within the RIPIDURABLE Project*, birds were used to characterize ecosystems*, to monitor environmental changes and to assess results of restoration measures. Bird surveys were carried out at different space and time scales using standardised point count methods on 8 watercourses in Portugal and France. Several aspects of riparian breeding bird community variation were assessed: along a decreasing gradient of vegetation complexity, along and upstream-downstream gradient, with different surrounding landscapes, with time, with management status, with time and management status, before and after river rehabilitation. Birds appear to be new and reliable indicators for assessing restoration of riparian ecosystems, complementary to those traditionally used

Approche patrimoniale et gestion de la voirie urbaine

La voirie urbaine, définie comme l'ensemble des espaces résiduels entre les parcelles cadastrales est un domaine public qui assure de nombreuses fonctions dans la ville. Outre la fonction circulatoire qui occupe plus de la moitié de cet espace, la rue est le support de réseaux enterrés, permet la desserte des espaces riverains, est un lieu d'activités et participe à la forme urbaine et à la qualité du cadre de vie. Ces divers usages sont parfois contradictoires, et les conflits d'appropriation entre catégories d'utilisateurs risquent de s'aggraver du fait d'une triple raréfaction relative, celle de l'espace de transport (congestion), celle de l'espace public urbain (cadre de vie) et celle des ressources des collectivités titulaires de ce bien. Malgré ces enjeux, la connaissance des caractéristiques physiques et techniques, et des usages de la voirie urbaine reste très limitée. Cela tient en partie à la faible attention portée jusqu'à maintenant au problème du maintien en l'état des infrastructures urbaines, alors que leur vieillissement va nécessiter un effort technique et financier de réfection ou de renouvellement important, au cours des prochaines décennies. Cela tient aussi à un éclatement des centres de gestion entre de nombreux services à compétences sectorielles et des operateurs chargés de fonctions spécifiques. Face à ceux nouveaux enjeux, l'approche patrimoniale vise à une gestion différente dont l'objectif est double : préserver la diversité des opportunités d'usage d'un bien commun, et assurer le maintien et le renouvellement du stock de voirie à long terme. Plus qu'un changement de méthodes, cette approche relève d'un changement d'éthique en tenant de redonner à la voirie son unicité, en rompant avec les processus sectoriels tant en termes de processus de décision que sur le plan de la gestion technique oui budgétaire de ce secteur.Voirie urbaine ; espace urbain ; gestion de la voirie urbaine ; usage de la voirie urbaine

Assessment of Aging of the Human Skin by In Vivo Ultrasonic Imaging

The ultrasonic imaging technique that we have developed provides cross-sectional images of human skin in vivo with a resolution of about 80 μm axially (i.e., deep into the skin) and 250 μm lateral (parallel to the surface). In order to study aging skin, we obtained ultrasonic images from the mid-fore-arm (volar and dorsal sides) of 142 women. Ultrasonically, on the images, the dermis appears composed of two bands: a dark superficial one where the ultrasonic waves are propagated in a relatively homogeneous or non-echogenic medium, and a deeper one, which is lighter in color, suggesting a heterogeneous medium. Our results show that skin is thicker on the dorsal than on the volar forearm. In contrast to previously published results, skin thickness remains constant until the seventh decade of life, diminishing thereafter. The relative thicknesses of the two bands show marked variations with age: a progressive thickening of the dark band, from zero in infants to approximately 75% of total skin thickness in aged subjects, while the light band shows the inverse trend. Comparing the amplitude of the bands on the volar and dorsal forearm, the relative thickness of the dark band is larger on the dorsal (exposed) side and increases with age. These findings and the analysis of variously stained biopsies taken in some of our patients lead us to assign this dark band to a zone in the upper dermis where the collagen network is delicate, dense, and well organized. This is supported by some data in the literature. The thickness of this subepidermal non-echogenic band appears to be a far more sensitive marker of skin aging at the dermal level than is the measurement of skin thickness

Le « Moustérien à denticulés » de la couche 20 de Combe-Grenal : implications techniques, économiques et fonctionnelles au sein du système de production Quina en Périgord

Le gisement de Combe-Grenal, célèbre pour son implication dans l’histoire de la recherche sur le Paléolithique moyen aquitain, offre une imposante séquence moustérienne contemporaine du Dernier Glaciaire (couches 1 à 37). Celle-ci se caractérise notamment par une série de couches attribuée au Moustérien de type Quina (couches 26 à 17), au sein de laquelle s’intercale la couche 20 attribuée par F. Bordes au Moustérien à denticulés. En apparence antinomique dans l’assise diachronique du Moustérien de type Quina, l’industrie de la couche 20 fait l’objet de cette contribution. Au regard des résultats obtenus, par le biais d’une démarche d’analyse mettant l’accent sur la caractérisation des modes de débitage et, surtout, sur la gestion des éclats (matrices), l’industrie de la couche 20 s’avère constituer un exemple singulier du potentiel techno-économico-fonctionnel offert par le système de production Quina.   

BIRDS AND SUSTAINABLE MANAGEMENT IN MEDITERRANEAN RIPARIAN AREAS: Bird studies in the RIPIDURABLE project

RIPIDURABLE is an INTERREG IIIC European Program involving 10 partners from Portugal, Spain, France and Greece. Scientists, technicians and local/regional authorities worked together to integrate knowledge, knowhow and practice, towards a rational conservation management of riparian zones. Birds can be used to characterize ecosystems, to monitor environmental changes or to assess results of restoration measures. We have conducted field surveys in order to assess breeding bird communities associated to riparian galleries in several watercourses, including issues as the relation with natural vegetation profiles, the influence of the surrounding matrix, the evolution with time or with habitat degradation, the effects of rehabilitation measures, and/or the importance of riparian galleries as ecological corridors for birds. Surveys at different space and time scales were carried out using standardised point count methods, on 8 watercourses in Portugal and France. We focused on different aspects of riparian breeding bird community variation: along a decreasing gradient of vegetal complexity (Tagus Basin), along an upstream-downstream gradient (Allier), with different surrounding landscapes (Sado, Guadiana and Tagus Basin), with time (Alcáçovas at a 10 years interval, Allier at 16 years interval), with management status (Vidourle), with time & management status (Rhône delta at a 12 years intervals), before & after river rehabilitation (Gandum). In addition we studied the dispersal of Barn Owls from upper Tagus Estuary along riparian corridors (TytoTagus Project), and also the importance of riparian habitats of the Guadiana basin on the autumn migration of trans-Saharan birds across the Iberian Peninsula. The RIPIDURABLE project offered the opportunity for further research currently included in national programs such as the Plan Loire Grandeur Nature which allows long term studies on riparian birds. Herein we briefly present some of the preliminary results of the bird studies carried out by partners from Portugal and France

La fracturation en split, une technique de production dans l’industrie lithique des Tares (Sourzac, Dordogne)

A partir du ré-examen de l’industrie du gisement des Tares et d’une expérimentation, une description de la fracturation en split est proposée. Elle se caractérise par une percussion rentrante, sur appui plus ou moins ferme, de direction strictement verticale, avec des percuteurs présentant une touche rectiligne.Following a re-examination of the lithic industry from Les Tares (Dordogne), as well as an experimental study, we propose a description of split fractures. They are produced by vertical (orthogonal) blows from inside the nodule, which is either rested on the ground or handheld. The hammer is characterised by a linear striking surface

La fracturation en split, une technique de production dans l’industrie lithique des Tares (Sourzac, Dordogne)

A partir du ré-examen de l’industrie du gisement des Tares et d’une expérimentation, une description de la fracturation en split est proposée. Elle se caractérise par une percussion rentrante, sur appui plus ou moins ferme, de direction strictement verticale, avec des percuteurs présentant une touche rectiligne.Following a re-examination of the lithic industry from Les Tares (Dordogne), as well as an experimental study, we propose a description of split fractures. They are produced by vertical (orthogonal) blows from inside the nodule, which is either rested on the ground or handheld. The hammer is characterised by a linear striking surface

Molecular organization of the human serotonin transporter at the air/water interface

AbstractThe serotonin transporter (SERT) is the target of several important antidepressant and psychostimulant drugs. It has been shown that under defined conditions, the transporter spread at the air/water interface was able to bind its specific ligands. In this paper, the interfacial organization of the protein has been assessed from dynamic surface pressure and ellipsometric measurements. For areas comprising between 10 400 and 7100 Å2/molecule, ellipsometric measurements reveal an important change in the thickness of the SERT film. This change was attributed to the reorientation of the transporter molecules from a horizontal to their natural predictive transmembrane orientation. The thickness of the SERT film at 7100 Å2/molecule was found to be approximately equal to 84 Å and coincided well with the theoretical value estimated from the calculations based on the dimensions of α-helices containing membrane proteins. These data suggest that the three-dimensional arrangement of the SERT may be represented as a box with lengths dz=83–85 Å and dy or dx=41–47 Å