A study of composite material damage induced by laser shock waves

A laser shock wave technique has been used to study the damage tolerance of T800/M21 CFRP (Carbon Fiber Reinforced Polymer) composite material with different lay_ups. Different levels of damage have been created according to various laser irradiation conditions. Several characterization methods such as Optical Microscopy, X-ray Radiography, or Interferometric Confocal Microscopy have been used to quantify these defects. The nature of the defects induced by the shock wave propagation has been studied. The sensitivity of the composite material damage to the shock conditions has been shown and quantified. Moreover, the experimental results gathered with each technique have been compared to each other and it leads to a better understanding of the CFRP behavior under high dynamic loading. These original results have enabled the definition of a specific damage criterion for CFRP under dynamic loading

Batch kernel SOM and related Laplacian methods for social network analysis

Large graphs are natural mathematical models for describing the structure of the data in a wide variety of fields, such as web mining, social networks, information retrieval, biological networks, etc. For all these applications, automatic tools are required to get a synthetic view of the graph and to reach a good understanding of the underlying problem. In particular, discovering groups of tightly connected vertices and understanding the relations between those groups is very important in practice. This paper shows how a kernel version of the batch Self Organizing Map can be used to achieve these goals via kernels derived from the Laplacian matrix of the graph, especially when it is used in conjunction with more classical methods based on the spectral analysis of the graph. The proposed method is used to explore the structure of a medieval social network modeled through a weighted graph that has been directly built from a large corpus of agrarian contracts

Guelb el Ahmar (Bathonian, Anoual Syncline, eastern Morocco): First continental flora and fauna including mammals from the Middle Jurassic of Africa

We report the discovery in Mesozoic continental “red beds” of Anoual Syncline, Morocco, of the new Guelb el Ahmar (GEA) fossiliferous sites in the Bathonian Anoual Formation. They produced one of the richest continental biotic assemblages from the Jurassic of Gondwana, including plants, invertebrates and vertebrates. Both the sedimentological facies and the biotic assemblage indicate a lacustrine depositional environment. The flora is represented by tree trunks (three families), pollen (13 species, five major clades) and charophytes. It suggests local forests and humid (non-arid) conditions. The vertebrate fauna is dominated by microvertebrates recovered by screening–washing. It is rich and diverse, with at least 29 species of all major groups (osteichthyans, lissamphibians, chelonians, diapsids, mammals), except chondrichthyans. It includes the first mammals discovered in the Middle Jurassic of Arabo-Africa. The GEA sites yielded some of the earliest known representatives of osteoglossiform fishes, albanerpetontid and caudate amphibians, squamates (scincomorphans, anguimorphan), cladotherian mammals, and likely choristoderes. The choristoderes, if confirmed, are the first found in Gondwana, the albanerpetontid and caudatan amphibians are among the very few known in Gondwana, and the anguimorph lizard is the first known from the Mesozoic of Gondwana. Mammals (Amphitheriida, cf. Dryolestida) remain poorly known, but are the earliest cladotherians known in Gondwana. The GEA biotic assemblage is characterized by the presence of Pangean and Laurasian (especially European) taxa, and quasi absence of Gondwanan taxa. The paleobiogeographical analysis suggests either a major fossil bias in Gondwana during the Middle Jurassic, and an overall vicariant Pangean context for the GEA assemblage, or alternatively, noticeable Laurasian (European) affinities and North-South dispersals. The close resemblance between the Bathonian faunas of GEA and Britain is remarkable, even in a Pangean context. The similarity between the local Anoual Syncline Guelb el Ahmar and Ksar Metlili faunas raises questions on the ?Berriasian age of the latter

Etude sur les déterminants professionnels agricoles et leurs effets sur la reproduction et le développement de l'enfant

Agricultural exposures, including pesticide exposure, have been associated with several negative effects on fertility, pregnancy and child development. Few studies focused on specific agricultural activity excepted floriculture and working in greenhouse and none was conducted in France. (1) More than 800 women, enroled in the AGRIculture & CANcer (AGRICAN) cohort and who reported a pregnancy since enrolment (2005) agreed to fill in 2 questionnaires. An increase of time to pregnancy was observed for women who worked on a farm, for those exposed to night work and to vibrations. Increased risks of spontaneous abortions or abnormalities were also observed in relation to agricultural work but these results need to be confirmed. (2) Multi-residue analytical method was developed and applied to women of childbearing age, working in crop-livestock farms. Twenty-five pesticides or metabolites were detected among 116 measured in urine samples. Herbicides were the most frequently detected, especially when women worked on corn-crop farms or were involved in breeding tasks. Glyphosate or its metabolite AMPA were detected in 85% of urine samples.Future project will allow us to investigate cognitive development of children born since 2005.Les expositions professionnelles agricoles, et notamment l’exposition aux pesticides, ont été associées à divers effets négatifs, sur la fertilité, le déroulement de la grossesse et le développement de l’enfant. Peu d’études se sont intéressées à des activités agricoles spécifiques excepté le travail sous serre et la floriculture et aucune n’a été à ce jour conduite en France. (1) L’interrogation de plus de 800 femmes, incluses dans la cohorte AGRIculture & CANcer (AGRICAN) et ayant eu une grossesse depuis l’inclusion (2005), grâce à 2 questionnaires rétrospectifs a montré un allongement du délai nécessaire à concevoir en lien avec l’emploi sur une exploitation agricole, le travail de nuit ou l’exposition à des vibrations. Des augmentations de risque d’avortements spontanés et de malformations ont également été observées mais restent à confirmer. (2) Le développement d’une méthode d’analyse multi-résidus a permis de mesurer 25 pesticides différents parmi 116 recherchés dans les urines de femmes travaillant sur des exploitations de poly-culture élevage. Les herbicides étaient les plus fréquemment détectés, notamment en lien avec la présence de maïs sur l’exploitation ou de tâches réalisées au contact des animaux d’élevage. Le glyphosate ou son métabolite AMPA étaient retrouvés dans 85% des échantillons.Un projet de recherche poursuivra les travaux engagés en s’intéressant au développement cognitif des enfants nés depuis 2005

Negative effects of agricultural exposures on human reproduction and child development

Les expositions professionnelles agricoles, et notamment l’exposition aux pesticides, ont été associées à divers effets négatifs, sur la fertilité, le déroulement de la grossesse et le développement de l’enfant. Peu d’études se sont intéressées à des activités agricoles spécifiques excepté le travail sous serre et la floriculture et aucune n’a été à ce jour conduite en France. (1) L’interrogation de plus de 800 femmes, incluses dans la cohorte AGRIculture & CANcer (AGRICAN) et ayant eu une grossesse depuis l’inclusion (2005), grâce à 2 questionnaires rétrospectifs a montré un allongement du délai nécessaire à concevoir en lien avec l’emploi sur une exploitation agricole, le travail de nuit ou l’exposition à des vibrations. Des augmentations de risque d’avortements spontanés et de malformations ont également été observées mais restent à confirmer. (2) Le développement d’une méthode d’analyse multi-résidus a permis de mesurer 25 pesticides différents parmi 116 recherchés dans les urines de femmes travaillant sur des exploitations de poly-culture élevage. Les herbicides étaient les plus fréquemment détectés, notamment en lien avec la présence de maïs sur l’exploitation ou de tâches réalisées au contact des animaux d’élevage. Le glyphosate ou son métabolite AMPA étaient retrouvés dans 85% des échantillons.Un projet de recherche poursuivra les travaux engagés en s’intéressant au développement cognitif des enfants nés depuis 2005.Agricultural exposures, including pesticide exposure, have been associated with several negative effects on fertility, pregnancy and child development. Few studies focused on specific agricultural activity excepted floriculture and working in greenhouse and none was conducted in France. (1) More than 800 women, enroled in the AGRIculture & CANcer (AGRICAN) cohort and who reported a pregnancy since enrolment (2005) agreed to fill in 2 questionnaires. An increase of time to pregnancy was observed for women who worked on a farm, for those exposed to night work and to vibrations. Increased risks of spontaneous abortions or abnormalities were also observed in relation to agricultural work but these results need to be confirmed. (2) Multi-residue analytical method was developed and applied to women of childbearing age, working in crop-livestock farms. Twenty-five pesticides or metabolites were detected among 116 measured in urine samples. Herbicides were the most frequently detected, especially when women worked on corn-crop farms or were involved in breeding tasks. Glyphosate or its metabolite AMPA were detected in 85% of urine samples.Future project will allow us to investigate cognitive development of children born since 2005

High-Temperature Nucleation of Cubic Silicon Carbide on (0001) Hexagonal-SiC Nominal Surfaces

International audienceThe development of 3C-SiC crystals from oriented hexagonal seed has always suffered from systematic twinning that appears during the nucleation step of the layer. To investigate the possibility to reduce or eliminate the incoherent twin boundaries at high temp. (for conditions close to bulk growth ones), we conducted an exptl. study on 3C-SiC nucleation. A mechanism for the selection of one 3C-SiC orientation among the two possible is proposed. It is based on a strong interaction between the a-SiC substrate steps and the anisotropic lateral expansion of the b-SiC domains. This model is confirmed by cross-sectional high resoln. transmission microscopy observations of the a-b interface. The mechanism is discussed with respect to the surface polarity (Si or C faces), the miscut angle, and the substrate polytype