MRI investigation of granular interface rheology using a new cylinder shear apparatus

The rheology of granular materials near an interface is investigated through proton magnetic resonance imaging. A new cylinder shear apparatus has been inserted in the MRI device, which allows the control of the radial confining pressure exerted by the outer wall on the grains and the measurement of the torque on the inner shearing cylinder. A multi-layer velocimetry sequence has been developed for the simultaneous measurement of velocity profiles in different sample zones, while the measurement of the solid fraction profile is based on static imaging of the sample. This study describes the influence of the roughness of the shearing interface and of the transverse confining walls on the granular interface rheology

Vivants puis morts : des victimes de violence intégrées au cimetière néolithique de Kadruka 23, Haute- Nubie (Soudan, 1re moitié du 5e millénaire av. J.-C.)

La butte funéraire de Kadruka 23 (Soudan, Northern State, Haute-Nubie), dans la zone multi-sites de Kadruka, à une dizaine de km à l’est du Nil (un peu au nord de Dongola, la capitale de l’état), est fouillée depuis 2014 par une équipe franco-soudanaise et a livré, au fil des campagnes de fouille, un véritable cimetière, daté de la première moitié du 5e millénaire av. J.-C. (par le matériel funéraire). Jusqu’à présent, 140 individus, inhumés de façon organisée sur moins de 110 m2, ont pu être..

Beyond economic advantages of agroforestry systems: what role and place of externalities in farmers' strategies?

Most agroforestry systems in the world results from local adaptation to climate, soils, crops and markets conditions for a specific crops combination and generally linked with a crop opportunity for export during colonial era which is mainly true for coffee, cocoa, rubber and clove. The focus is then put on income generation and rapid monetarization of local livelihoods. Some systems are purely resulting from local demands such as coconut tree based systems with focus on food for self-consumption. Some systems are based on a main cash crop (rubber, cocoa, coffee…). In all cases, production diversification is a key element for a better global resilience through production of the main crops and fruits, firewood, timber wood, resins, rattan… and other plants such as medicinal plants. Some products are sold and some self-consumed largely depending on access to markets. The “useful” biodiversity is then largely known and combined to fulfill a better resilience, based on crop diversification in order not to depend only on one product and generate in the short/mid term several sources of income. But the “non useful” biodiversity or more exactly the non-marketable biodiversity is also producing ecologic services in the long run that are highly appreciated and generally well known by local people. What is the role of these externalities in agroforestry development and associated farmers' strategies. If most income analyses have difficulties in providing a value to these externalities, they may have a key role in farmers' choice and preference in agroforestry rather than monoculture when they have the choice. In other words, if profitability and short term income generation are often a priority for most smallholders, long term stability, positive externalities provided by ecological services of agroforestry systems and the search for a better resilience are key factors in developing agroforestry strategies in the long run. We provide several examples of that trend for rubber agroforestry in Indonesia and Thailand, clove agroforestry in Madagascar and coffee agroforestry in Nicaragu

SAW RFID devices using connected IDTs as an alternative to conventional reflectors for harsh environments

International audienceRemote interrogation of surface acoustic wave ID-tags imposes a high signal amplitude which is related to a high coupling coefficient value (K 2) and low propagation losses (α). In this paper, we propose and discuss an alternative configuration to the standard one. Here, we replaced the conventional configuration, i.e. one interdigital transducer (IDT) and several reflectors, by a series of electrically connected IDTs. The goal is to increase the amplitude of the detected signal using direct transmission between IDTs instead of the reflection from passive reflectors. This concept can therefore increase the interrogation scope of ID-tags made on conventional substrate with high K 2 value. Moreover, it can also be extended to suitable substrates for harsh environments such as high temperature environments: the materials used exhibit limited performances (low K 2 value and relatively high propagation losses) and are therefore rarely used for identification applications. The concept was first tested and validated using the lithium niobate 128°Y-X cut substrate, which is commonly used in ID-tags. A good agreement between experimental and numerical results was obtained for the promising concept of connected IDTs. The interesting features of the structure were also validated using a langasite substrate, which is well-known to operate at very high temperatures. Performances of both substrates (lithium niobate and langasite) were tested with an in-situ RF characterization up to 600°C. Unexpected results regarding the resilience of devices based on congruent lithium niobate were obtained. Index Terms-high temperature, lithium niobate, radio frequency identification (RFID), surface acoustic wave (SAW

Retinoic Acid Controls the Bilateral Symmetry of Somite Formation in the Mouse Embryo

A striking characteristic of vertebrate embryos is their bilaterally symmetric body plan, which is particularly obvious at the level of the somites and their derivatives such as the vertebral column. Segmentation of the presomitic mesoderm must therefore be tightly coordinated along the left and right embryonic sides. We show that mutant mice defective for retinoic acid synthesis exhibit delayed somite formation on the right side. Asymmetric somite formation correlates with a left-right desynchronization of the segmentation clock oscillations. These data implicate retinoic acid as an endogenous signal that maintains the bilateral synchrony of mesoderm segmentation, and therefore controls bilateral symmetry, in vertebrate embryos

Gestion des appels d'urgence routiers : contexte et perspectives d'évolution

Face à la diversification des moyens d'appels à disposition des usagers de la route en détresse, se pose la question de l'évolution du RAU (réseau d'appels d'urgence), équipement routier dédié aux urgences. Pour l'évaluer ce document présente :Le diagnostic de fonctionnement du RAU et des appels d'urgence au travers des aspects techniques(RAU, téléphonie mobile. . .), de l'organisation des centres d'appels d'urgence, de l'acheminements des appels, d'enquêtes auprès des acteurs et des usagers.Le fonctionnement dans quatre pays européens, synthèse d'une étude faite en Allemagne,Grande-Bretagne, Italie, Hollande.Une corrélation accidents, appels d'urgence : croisement géographique de l'implantation des PAU sur RN avec des données accidents.Des perspectives d'évolutions sur le plan technique, sur l'organisation et l'acheminement des appels.Une synthèse de propositions et de suites à donner

beDNA : un projet visant à la collection systématique d’échantillons humains archéologiques à vocation paléogénétique – une première expérimentation

La paléogénétique occupe désormais une place importante dans les problématiques archéologiques. Toutefois, les analyses d’ADN ancien peuvent être desservies, voire empêchées, par l’état de préservation des échantillons en raison de contamination par de l’ADN moderne ou de mauvaises conditions de stockage. Le projet beDNA, "banque d’échantillons et de Données Nationale Archéogénétique", souhaite donner les moyens d’analyses paléogénétiques futures, en proposant le stockage systématique d’échantillons des squelettes humains tenant compte des contraintes inhérentes à la préservation de l’ADN ancien. Le projet implique (1) un protocole systématique d’échantillonnage "propre" des restes humains sur le terrain commun à toutes les opérations archéologiques, (2) un espace de stockage dédié à ces échantillons adapté à la conservation de l’ADN ancien, (3) une base de données faisant le lien entre les sites et les échantillons conservés dans la banque, (4) l’approbation par l’État des demandes d’analyse d’échantillons après expertise. La phase de test du projet, initiée en septembre 2020 sur la région Île-de-France, nous a permis d’évaluer et d’ajuster le protocole d’échantillonnage sur le terrain et les dispositifs de transfert vers la banque. Cette note présente les étapes envisagées pour chaque échantillon, depuis les terrains jusqu’aux laboratoires d’analyse génétique, ainsi que le déroulement de sa phase test, en cours, et les premiers retours d’expérience.Palaeogenetics is becoming increasingly important in tackling archaeological issues. However, analyses of ancient DNA can be hampered or even prevented by the state of preservation of samples due to poor storage conditions, and because of contamination by modern DNA. The beDNA project for a national archaeological genetic data and sample bank (banque d’échantillons et de Données Nationale Archéogénétique) is developing the means to enable future palaeogenetic analyses by systematically storing human skeletal samples, with the constraints inherent to the preservation of ancient DNA taken into account. This project comprises (1) a systematic protocol for "clean" sampling of human remains to be common to all archaeological operations, (2) a dedicated storage space for samples, suited to aDNA preservation, (3) a database linking sites with the samples stored in the bank, (4) approval of sample analysis requests by authorities, after expert review. The test phase of the project, which began in September 2020 in the Île-de-France region, enabled us to evaluate and adjust both the sampling protocol in the field and the transfer process to the beDNA bank. This note describes the different stages envisaged for each sample, from the archaeological field to the genetics laboratory, as well as the development of the experimental phase and initial feedback from it

Impaired skin wound healing in peroxisome proliferator–activated receptor (PPAR)α and PPARβ mutant mice

We show here that the α, β, and γ isotypes of peroxisome proliferator–activated receptor (PPAR) are expressed in the mouse epidermis during fetal development and that they disappear progressively from the interfollicular epithelium after birth. Interestingly, PPARα and β expression is reactivated in the adult epidermis after various stimuli, resulting in keratinocyte proliferation and differentiation such as tetradecanoylphorbol acetate topical application, hair plucking, or skin wound healing. Using PPARα, β, and γ mutant mice, we demonstrate that PPARα and β are important for the rapid epithelialization of a skin wound and that each of them plays a specific role in this process. PPARα is mainly involved in the early inflammation phase of the healing, whereas PPARβ is implicated in the control of keratinocyte proliferation. In addition and very interestingly, PPARβ mutant primary keratinocytes show impaired adhesion and migration properties. Thus, the findings presented here reveal unpredicted roles for PPARα and β in adult mouse epidermal repair