On the Rapid Increase of Intermittency in the Near-Dissipation Range of Fully Developed Turbulence

Intermittency, measured as log(F(r)/3), where F(r) is the flatness of velocity increments at scale r, is found to rapidly increase as viscous effects intensify, and eventually saturate at very small scales. This feature defines a finite intermediate range of scales between the inertial and dissipation ranges, that we shall call near-dissipation range. It is argued that intermittency is multiplied by a universal factor, independent of the Reynolds number Re, throughout the near-dissipation range. The (logarithmic) extension of the near-dissipation range varies as \sqrt(log Re). As a consequence, scaling properties of velocity increments in the near-dissipation range strongly depend on the Reynolds number.Comment: 7 pages, 7 figures, to appear in EPJ

: THE BRONZE AGE PAINTED CAVE OF " LES FRAUX ", DORDOGNE (FRANCE)

International audienceFor six years, an interdisciplinary team of archaeologists, surveyors, environmentalists and archaeometrists have jointly carried out the study of a Bronze Age painted cave, registrered in the French Historical Monuments. The archaeological cave of Les Fraux (Saint-Martin-de-Fressengeas, Dordogne) forms a wide network of galleries, characterized by the exceptional richness of its archaeological remains such as ceramic and metal deposits, parietal representation and about domestic fireplaces. This cave is the only protohistorical site in Europe wherein are gathered testimonies of domestic, spiritual and artistic activities. Fortunately, the cave was closed at the end of the Bronze Age, following to the collapse of its entrance. The site was re-discovered in 1989 and its study started in 2007. The study in progress takes place in a new kind of tool founded by the CNRS's Institute of Ecology and Environment. The purpose of this observatory is the promotion of new methodologies and experimental studies in Global Ecology. In that framework, 3D models of the cave constitute the common work support and the best way for scientific communication for the various studies conducted on the site by nearly forty researchers. In this specific context, a partnership among archaeologists and surveyors from INSA Strasbourg allows the team to develop, in an interdisciplinary way, new methods of data acquiring based on contact-free measurements techniques in order to acquire a full 3D-documentation. This work is conducted in compliance with the integrity of the site. Different techniques based on Terrestrial Laser Scanning, Digital Photogrammetry and Spatial Imaging System have been used in order to generate a geometric and photorealistic 3D model from the combination of point clouds and photogrammetric images, for both visualization and accurate documentation purposes. Various scales of acquiring and diverse resolutions have been applied according to the subject: global volume cave, parietal representations, deposits... The aim of this paper is to issue a statement of the different 3D technologies tested in this outstanding site and the integration of magnetic measurements in the models

Thermal characterization of ancient hearths from the cave of Les Fraux (Dordogne, France) by thermoluminescence and magnetic susceptibility measurements

International audienceNumerous sorts of evidence of fires were observed in the cave of Les Fraux (Dordogne, France) and in particular the effects of fire on sediment were studied for a better understanding of their use centuries ago. Our present objective is the evaluation of the firing intensity by determining the past temperature (paleotemperature) attained by the topmost sediment of the archaeological fires. The principle of paleotemperature determination is based on the thermoluminescence (TL) properties of quartz and the magnetic susceptibility of the sediment. By comparing the TL signal of anciently heated quartz to the TL signal of thermal references made in the laboratory, we were able to obtain a maximal equivalent temperature attained for each sample extracted from ancient fires. The magnetic susceptibility (previously measured on the hearth surface) could thus be estimated as a function of temperature. The main result of this study is the temperature mapping of the hearth which can be used as meaningful information about the ancient firing intensity

Caractérisation thermique de foyers de l'âge du Bronze de la grotte des Fraux (Dordogne)

International audienceThe Les Fraux cave (Dordogne, France) was occupied during the Bronze Age. It contained numerous hearth features. The questions related to the function of the cave and more particularly of the hearth features involved a multidisciplinary study of these remains. The aim of this paper is to present the methods applied for the study of the hearths. The analysis combined thermoluminescence (TL) of the quartz grains and magnetic susceptibility principally registered by the iron oxides contained in the sediments (whether heated or not). For each sample, the TL permits to obtain the corresponding temperature (palaeotemperature) by comparison between the TL curves of the samples and those of the thermal references. The relationship established between the palaeotemperature and the magnetic susceptibility allows converting magnetic susceptibility to palaeotemperatures reached by the sediment on a larger surface. This permits to characterize the intensity of heat attained in these hearths and to contribute to the determination of the function of this site through the comparison with experimental firesLa grotte des Fraux (Dordogne, France), occupée à l'âge du Bronze, présente de nombreuses structures de combustion. Les questions relatives à la fonction du site et plus particulièrement des foyers, ont entrainé la mise en place d'une étude pluridisciplinaire de ces structures. L'objet de cet article est de présenter la méthodologie mise en oeuvre pour l'étude de ces foyers. Elle s'appuie sur un couplage entre la thermoluminescence (TL) des grains de quartz et la susceptibilité magnétique principalement portée par les oxydes de fer contenus dans les sédiments (chauffés ou non). Pour chaque prélèvement, la TL permet d'obtenir une température équivalente (paléotempérature) par comparaison entre les courbes TL correspondantes et celles de références thermiques. La relation établie entre la paléotempérature et la susceptibilité magnétique permet de traduire la carte de susceptibilité magnétique en paléotempératures atteintes par le sédiment sur une surface étendue. L'objectif est de caractériser l'intensité de chauffe de ces foyers et, par une comparaison avec des feux expérimentaux, de contribuer à préciser la fonction de ce site

Numerical simulations of the Euler system with congestion constraint

In this paper, we study the numerical simulations for Euler system with maximal density constraint. This model is developed in [1, 3] with the constraint introduced into the system by a singular pressure law, which causes the transition of different asymptotic dynamics between different regions. To overcome these difficulties, we adapt and implement two asymptotic preserving (AP) schemes originally designed for low Mach number limit [2,4] to our model. These schemes work for the different dynamics and capture the transitions well. Several numerical tests both in one dimensional and two dimensional cases are carried out for our schemes

APRÈS LE DÉLUGE : ÉVOLUTION GÉOMORPHOLOGIQUE DU DELTA DU DANUBE APRÈS LA RECONNEXION MER NOIRE - MÉDITERRANÉE ET SES IMPLICATIONS SUR LE PEUPLEMENT ÉNÉOLITHIQUE / CHALCOLITHIQUE

International audienceIn this work, we document the evolution of the upper Danube delta (i.e. blocked delta) using archaeological, geomorphological and geoarchaeological approaches, after the discovery, in the 90's, of the oldest human settlement (Eneolithic/Chalcolithic) close to Mila 23 district. In-site and out-site fieldwork allows us to refine the Danube delta early evolution from 5,600 to 4,000 cal. yr BC. During this period, it functions like a fresh bayhead delta, flowing into a huge lagoon isolated from the open sea by the Letea-Caraorman spit. Then, lagoon water level rose rapidly due to an eustatic rise, and possibly from an unusual highstand of sealevel resulting from wet conditions. The settlement was then partially flooded and abandoned around 4,450 cal. yr BC.Dans ce travail, l'évolution de la zone interne du delta du Danube est appréhendée à partir de travaux géoarchéologiques et géomorphologiques réalisés dans le district de Mila 23, suite à la découverte de la plus vieille occupation humaine (énéolithique/ chalcolithique) du delta dans les années 90. Les travaux sur site et hors site ont permis de préciser les stades précoces de l'évolution du delta entre 5 600 et 4 000 ans cal. av. J.-C. Celui-ci évolue comme un delta lagunaire en eau douce, s'épandant dans un large lagon séparé de la mer par la ride de Letea-Caraorman. La remontée rapide du niveau lagunaire, sous l'effet de la remontée eustatique et peut-être d'une sur cote liée à un événement humide, ont conduit à une submersion partielle du site et probablement à son abandon vers 4 450 ans cal. av. J.-C

Aftermath of the flooding : geomorphological evolution of the Danube delta after the black sea-mediterranean reconnection and its implications on eneolithic settlements

International audienceIn this article we document the evolution of the internal area of the Danube Delta (i.e. the blocked delta) starting from the geo-archaeological and geomorphological investigations performed at Mila 23 district, following the discovery of the oldest human settlement in the Delta. The in-site and out-site field work and coring allowed us to specify the delta's early stages of evolution from 5600 to 4000 CAL BC. During this period, the site evolves as a freshwater bay-head delta flowing into a huge lagoon isolated from the open sea by Letea-Caraorman spits. The rapid sedimentation rate in the lagoon is interpreted as a response to base-level rise and overflooding as a result of humid conditions during 6-5 ky RCC, leading to the partial submersion of the site and probably to its abandonment around 4450 CAL BC

Dendritic cells are defective in breast cancer patients: a potential role for polyamine in this immunodeficiency

INTRODUCTION: Dendritic cells (DCs) are antigen-presenting cells that are currently employed in cancer clinical trials. However, it is not clear whether their ability to induce tumour-specific immune responses when they are isolated from cancer patients is reduced relative to their ability in vivo. We determined the phenotype and functional activity of DCs from cancer patients and investigated the effect of putrescine, a polyamine molecule that is released in large amounts by cancer cells and has been implicated in metastatic invasion, on DCs. METHODS: The IL-4/GM-CSF (granulocyte–macrophage colony-stimulating factor) procedure for culturing blood monocyte-derived DCs was applied to cells from healthy donors and patients (17 with breast, 7 with colorectal and 10 with renal cell carcinoma). The same peroxide-treated tumour cells (M74 cell line) were used for DC pulsing. We investigated the effects of stimulation of autologous lymphocytes by DCs pulsed with treated tumour cells (DC-Tu), and cytolytic activity of T cells was determined in the same target cells. RESULTS: Certain differences were observed between donors and breast cancer patients. The yield of DCs was dramatically weaker, and expression of MHC class II was lower and the percentage of HLA-DR(-)Lin(- )cells higher in patients. Whatever combination of maturating agents was used, expression of markers of mature DCs was significantly lower in patients. Also, DCs from patients exhibited reduced ability to stimulate cytotoxic T lymphocytes. After DC-Tu stimulation, specific cytolytic activity was enhanced by up to 40% when DCs were from donors but only up to 10% when they were from patients. IFN-γ production was repeatedly found to be enhanced in donors but not in patients. By adding putrescine to DCs from donors, it was possible to enhance the HLA-DR(-)Lin(- )cell percentage and to reduce the final cytolytic activity of lymphocytes after DC-Tu stimulation, mimicking defective DC function. These putrescine-induced deficiencies were reversed by treating DCs with all-trans retinoic acid. CONCLUSION: These data are consistent with blockade of antigen-presenting cells at an early stage of differentiation in patients with breast cancer. Putrescine released in the microenvironmement of DCs could be involved in this blockade. Use of all-trans retinoic acid treatment to reverse this blockade and favour ex vivo expansion of antigen-specific T lymphocytes is of real interest

Construction of a subgenomic CV-B3 replicon expressing emerald green fluorescent protein to assess viral replication of a cardiotropic enterovirus strain in cultured human cells

Coxsackieviruses B (CV-B) (Picornaviridae) are a common infectious cause of acute myocarditis in children and young adults, a disease, which is a precursor to 10-20% of chronic myocarditis and dilated cardiomyopathy (DCM) cases. The mechanisms involved in the disease progression from acute to chronic myocarditis phase and toward the DCM clinical stage are not fully understood but are influenced by both viral and host factors. Subgenomic replicons of CV-B can be used to assess viral replication mechanisms in human cardiac cells and evaluate the effects of potential antiviral drugs on viral replication activities. Our objectives were to generate a reporter replicon from a cardiotropic prototype CV-B3/28 strain and to characterize its replication properties into human cardiac primary cells. To obtain this replicon, a cDNA plasmid containing the full CV-B3/28 genome flanked by a hammerhead ribozyme sequence and an MluI restriction site was generated and used as a platform for the insertion of sequences encoding emerald green fluorescent protein (EmGFP) in place of those encoding VP3. In vitro transcribed RNA from this plasmid was transfected into HeLa cells and human primary cardiac cells and was able to produce EmGFP and VP1-containing polypeptides. Moreover, non-structural protein biological activity was assessed by the specific cleavage of eIF4G1 by viral 2A(pro). Viral RNA replication was indirectly demonstrated by inhibition assays, fluoxetine was added to cell culture and prevented the EmGFP synthesis. Our results indicated that the EmGFP CV-B3 replicon was able to replicate and translate as well as the CV-B3/28 prototype strain. Our EmGFP CV-B3 replicon will be a valuable tool to readily investigate CV-B3 replication activities in human target cell models

A marine biodiversity observation network for genetic monitoring of hard-bottom communities (ARMS-MBON)

Marine hard-bottom communities are undergoing severe change under the influence of multiple drivers, notably climate change, extraction of natural resources, pollution and eutrophication, habitat degradation, and invasive species. Monitoring marine biodiversity in such habitats is, however, challenging as it typically involves expensive, non-standardized, and often destructive sampling methods that limit its scalability. Differences in monitoring approaches furthermore hinders inter-comparison among monitoring programs. Here, we announce a Marine Biodiversity Observation Network (MBON) consisting of Autonomous Reef Monitoring Structures (ARMS) with the aim to assess the status and changes in benthic fauna with genomic-based methods, notably DNA metabarcoding, in combination with image-based identifications. This article presents the results of a 30-month pilot phase in which we established an operational and geographically expansive ARMS-MBON. The network currently consists of 20 observatories distributed across European coastal waters and the polar regions, in which 134 ARMS have been deployed to date. Sampling takes place annually, either as short-term deployments during the summer or as long-term deployments starting in spring. The pilot phase was used to establish a common set of standards for field sampling, genetic analysis, data management, and legal compliance, which are presented here. We also tested the potential of ARMS for combining genetic and image-based identification methods in comparative studies of benthic diversity, as well as for detecting non-indigenous species. Results show that ARMS are suitable for monitoring hard-bottom environments as they provide genetic data that can be continuously enriched, re-analyzed, and integrated with conventional data to document benthic community composition and detect non-indigenous species. Finally, we provide guidelines to expand the network and present a sustainability plan as part of the European Marine Biological Resource Centre (www.embrc.eu).Peer reviewe