Role of the inter‐ply microstructure in the consolidation quality of high‐performance thermoplastic composites

Consolidation of Carbon Fiber (CF)/high-performance thermoplastic compos-ites is much less understood than the one of their thermoset counterparts. It isusually assumed that the consolidation quality is directly linked to the removalof voids within the sample during consolidation, leading to mechanical proper-ties suitable for aerospace applications. A systematic study of the temporalevolution of CF/polyetherketoneketone (PEKK) samples' microstructure con-solidated under low pressure in a rheometer is related to the increase in inter-laminar shear strength. The results show that despite similar void contentswell-below 1 vol%, samples can present significant differences in ILSS values,from 80 to 95 MPa for cross-ply samples, and from 98 to 112 MPa for unidirec-tional (UD) ones. A microstructural analysis shows that, for these materials,consolidation quality is rather related to a reorganization of the inter-ply, aresin-rich ( 70 vol%) region of typical thickness 10μm which is slowly repo-pulated in fibers during consolidation

An efficient and reliable steel assembly modelling scheme using second-order cone programming and dual error estimator.

International audienceThe modelling of steel assemblies under static loading using elastic, elasto-plastic or rigid perfectly plastic material coupled with frictional unilateral contact is discussed within the framework of the second-order cone programming (SOCP). In this article, using a combination of the hard-contact conditions coupled with an associated Coulomb frictional behaviour, the contact conditions are written as second-order cones using a pair of dual kinematic and static variables. The minimizations are then formulated as a pair of dual SOCP problems which are then solved using a state-of-the art primal-dual interior point method (IPM). In comparison with a Newton-Raphson algorithm generally used to solve nonlinear problems, the IPM shows better robustness and efficiency and specially for limit analysis where the Newton-Raphson algorithm cannot be used and allows us to formulate the problem using a dual approach. This yields an optimal pair of dual kinematically and statically admissible fields which allows the user to assess the quality of convergence and to efficiently calculate a discretization error estimator which includes a contact surface error term and plasticity error terms. An efficient remesh scheme, based on the local contributions of the elements to the global error, can then be used to limit the number of elements in the 3D analysis. This article illustrates the whole process in some examples of typical steel assemblies. This will allow structural engineers to evaluate the quality of their results and to produce better and more economical designs

Estrategias innovadoras para favorecer el desarrollo de competencias. Aplicación en la enseñanza de ingeniería de las reacciones químicas

Se describe en espacio y tiempo una propuesta de enseñanza- aprendizaje innovadora implementada en alumnos de cuarto año cursando la asignatura de Ingeniería de las Reacciones de la carrera de Ingeniería Química de la Facultad Regional Resistencia de la Universidad Tecnológica Nacional. La situación problemática aborda la complejidad de diversos aspectos que intervienen en ella durante 8 períodos académicos en los cuales ha sido desarrollada. La metodología fue implementada con el fin de desarrollar competencias profesionales articulando contenidos de la asignatura con la aplicación en el campo profesional a través de una visita a industria química de la región.

Nonlinear modes of clarinet-like musical instruments

The concept of nonlinear modes is applied in order to analyze the behavior of a model of woodwind reed instruments. Using a modal expansion of the impedance of the instrument, and by projecting the equation for the acoustic pressure on the normal modes of the air column, a system of second order ordinary differential equations is obtained. The equations are coupled through the nonlinear relation describing the volume flow of air through the reed channel in response to the pressure difference across the reed. The system is treated using an amplitude-phase formulation for nonlinear modes, where the frequency and damping functions, as well as the invariant manifolds in the phase space, are unknowns to be determined. The formulation gives, without explicit integration of the underlying ordinary differential equation, access to the transient, the limit cycle, its period and stability. The process is illustrated for a model reduced to three normal modes of the air column

A Low Protein Diet Increases the Hypoxic Tolerance in Drosophila

Dietary restriction is well known to increase the life span of a variety of organisms from yeast to mammals, but the relationships between nutrition and the hypoxic tolerance have not yet been considered. Hypoxia is a major cause of cell death in myocardial infarction and stroke. Here we forced hypoxia-related death by exposing one-day-old male Drosophila to chronic hypoxia (5% O(2)) and analysed their survival. Chronic hypoxia reduced the average life span from 33.6 days to 6.3 days when flies were fed on a rich diet. A demographic analysis indicated that chronic hypoxia increased the slope of the mortality trajectory and not the short-term risk of death. Dietary restriction produced by food dilution, by yeast restriction, or by amino acid restriction partially reversed the deleterious action of hypoxia. It increased the life span of hypoxic flies up to seven days, which represented about 25% of the life time of an hypoxic fly. Maximum survival of hypoxic flies required only dietary sucrose, and it was insensitive to drugs such as rapamycin and resveratrol, which increase longevity of normoxic animals. The results thus uncover a new link between protein nutrition, nutrient signalling, and resistance to hypoxic stresses

Bridging the Gap Between Nonlinear Normal Modes and Modal Derivatives

Nonlinear Normal Modes (NNMs) have a clear conceptual relation to the classical linear normal modes (LNMs), yet they offer a solid theoretical framework for interpreting a wide class of non-linear dynamical phenomena with no linear counterpart. The main difficulty associated with NNMs is that their calculation for large-scale models is expensive, particularly for distributed nonlinearities. Repeated direct time integrations need to be carried out together with extensive sensitivity analysis to reproduce the frequency-energy dependence of the modes of interest. In the present paper, NNMs are computed from a reduced model obtained using a quadratic transformation comprising LNMs and Modal Derivatives (MDs). Previous studies have shown that MDs can capture the essential dynamics of geometrically nonlinear structures and can greatly reduce the computational cost of time integration. A direct comparison with the NNMs computed from another standard reduction technique highlights the capability of the proposed reduction method to capture the essential nonlinear phenomena. The methodology is demonstrated using simple examples with 2 and 4 degrees of freedom.BeIPD-COFUND outgoing fellowship: Managing bifurcations of nonlinear mechanical systems using experimental continuation technique

Drosophila Genome-Wide RNAi Screen Identifies Multiple Regulators of HIF–Dependent Transcription in Hypoxia

Hypoxia-inducible factors (HIFs) are a family of evolutionary conserved alpha-beta heterodimeric transcription factors that induce a wide range of genes in response to low oxygen tension. Molecular mechanisms that mediate oxygen-dependent HIF regulation operate at the level of the alpha subunit, controlling protein stability, subcellular localization, and transcriptional coactivator recruitment. We have conducted an unbiased genome-wide RNA interference (RNAi) screen in Drosophila cells aimed to the identification of genes required for HIF activity. After 3 rounds of selection, 30 genes emerged as critical HIF regulators in hypoxia, most of which had not been previously associated with HIF biology. The list of genes includes components of chromatin remodeling complexes, transcription elongation factors, and translational regulators. One remarkable hit was the argonaute 1 (ago1) gene, a central element of the microRNA (miRNA) translational silencing machinery. Further studies confirmed the physiological role of the miRNA machinery in HIF–dependent transcription. This study reveals the occurrence of novel mechanisms of HIF regulation, which might contribute to developing novel strategies for therapeutic intervention of HIF–related pathologies, including heart attack, cancer, and stroke

Study protocol for a pragmatic cluster randomized controlled trial to improve dietary diversity and physical fitness among older people who live at home (the “ALAPAGE study”)

Background : Diet and physical activity are key components of healthy aging. Current interventions that promote healthy eating and physical activity among the elderly have limitations and evidence of French interventions’ effectiveness is lacking. We aim to assess (i) the effectiveness of a combined diet/physical activity intervention (the “ALAPAGE” program) on older peoples’ eating behaviors, physical activity and fitness levels, quality of life, and feelings of loneliness; (ii) the intervention’s process and (iii) its cost effectiveness. Methods : We performed a pragmatic cluster randomized controlled trial with two parallel arms (2:1 ratio) among people ≥60 years old who live at home in southeastern France. A cluster consists of 10 people participating in a “workshop” (i.e., a collective intervention conducted at a local organization). We aim to include 45 workshops randomized into two groups: the intervention group (including 30 workshops) in the ALAPAGE program; and the waiting-list control group (including 15 workshops). Participants (expected total sample size: 450) will be recruited through both local organizations’ usual practices and an innovative active recruitment strategy that targets hard-to-reach people. We developed the ALAPAGE program based on existing workshops, combining a participatory and a theory-based approach. It includes a 7-week period with weekly collective sessions supported by a dietician and/or an adapted physical activity professional, followed by a 12-week period of post-session activities without professional supervision. Primary outcomes are dietary diversity (calculated using two 24-hour diet recalls and one Food Frequency Questionnaire) and lower-limb muscle strength (assessed by the 30-second chair stand test from the Senior Fitness Test battery). Secondary outcomes include consumption frequencies of main food groups and water/hot drinks, other physical fitness measures, overall level of physical activity, quality of life, and feelings of loneliness. Outcomes are assessed before the intervention, at 6 weeks and 3 months later. The process evaluation assesses the fidelity, dose, and reach of the intervention as its causal mechanisms (quantitative and qualitative data). Discussion : This study aims to improve healthy aging while limiting social inequalities. We developed and evaluated the ALAPAGE program in partnership with major healthy aging organizations, providing a unique opportunity to expand its reach

The two coffins of Mesehti S1C (CG 28118) - S2C (CG 28119) : research on the organization of iconography and texts

Le double sarcophage de Mésehti, nomarque d’Assiout et grand prêtre d’Anubis et d’Oupouaout, est conservé au Musée du Caire. Sur l’extérieur des couvercles et des parois sont inscrits des textes religieux et funéraires peu habituels et pour partie dérivés des Textes des Pyramides (Livre de Nout). Seul le sarcophage intérieur porte un décor figuré à l’intérieur. Le couvercle du sarcophage intérieur est décoré d’une horloge stellaire diagonale (HSD) associée à deux registres de TS. Mais ces deux sarcophages servent surtout de support à une grande quantité de Textes des Sarcophages. Dans ce corpus, on constate la répétition d’un grand nombre de chapitres, sur une même paroi par le phénomène d’emboîtement et sur des parois différentes par l’association en séries ou séquences. Le choix des textes et de leur enchaînement répond à un souci d’établir un discours relatif au devenir au défunt dans l’au-delà. L’organisation spatiale par le choix des parois et la répétition de certains TS y est subtile et performative. La répétition des TS met en évidence une adaptation des textes à la paroi support et au contexte du discours. À cette mise en espace, à cet aspect discursif, est associée une insertion dans le temps par la présence de l’HSD et par l’établissement d’un cycle de lecture des parois des deux sarcophages. Cette étude de l’organisation du décor et des textes est complétée par une analyse de certains thèmes choisis.Mesehti was nomarch from Assiut and Great Priest of Anubis and Wepwawet during the Middle Kingdom. His two coffins are now preserved in Cairo Museum. The outer decoration is unusual and inspired by Pyramid Texts (Book of Nut). Only the inner coffin is decorated. We find a Diagonal Star Clock under the lid of this coffin. But, for the most, many spells of Coffin Texts are inscribed inside the two coffins. Many of these spells are repeated on one side with the “setting phenomenon” and on different sides in so called series and sequences. The choice of the spells, their connections and their positions on selected sides and lids demonstrate the discourse about the deceased in the beyond. We find a subtle organization of these CT in the oriented space of the two coffins and in the cycles of time

Les représentations sociales de la profession de sage-femme chez des femmes enceintes après les manifestations d'octobre 2013Étude qualitative réalisée dans les départements des Bouches-du-Rhône et du Vaucluse

Introduction: « So, midwife, how many years after a nurse? ». The profession of midwife seems to be little known. This "beautiful craft" has evolved over time in terms of skills, training and knowledge making it unclear to the public. It is a medical profession with many different skills that are widening regularly. Three years have elapsed since the beginning of the strike and it seemed interesting to know what were the social representations of pregnant women about the roles and competences of the midwifery profession.Materials and methods: In this qualitative study, 16 pregnant women in the departments of Bouches-du-Rhône and Vaucluse played the game, accepting on a voluntary basis to participate in semi-structured interviews.Results: The outcomes of these interviews showed that the midwifery profession had several representations: a medical profession with several skills, a profession around the newborn, etc.Analysis and discussion: By comparing the results of the study with those of the Marine Arthenay’s work in 2012, an evolution of representations of the profession of midwife, in the direction of a better knowledge of this profession could be observed.Conclusion: The midwifery profession, composed of women and men, is seen by the interviewed patients as a medical profession with many competences. An extension of these competences, as well as an information campaign took place in 2016. The impact of this information campaign on knowledge of the profession of midwife, as well as the opinion of midwives on the extension of their competence can be questioned.Introduction : « Et donc, sage-femme, c’est combien d’années après infirmière ? ». La profession de sage-femme semble être peu connue. Ce « si beau métier » a évolué au fil du temps en termes de compétences, de formation, de connaissances le rendant flou aux yeux de la population. Il s’agit d’une profession médicale avec de nombreuses compétences variées qui s’élargissent régulièrement. Trois années se sont écoulées depuis le début du mouvement de grève et il a paru intéressant de savoir quelles étaient les représentations sociales des femmes enceintes sur lesrôles et les compétences de la profession de sage-femme.Matériels et méthode : Lors de cette étude qualitative, 16 femmes enceintes, dans les départements des Bouches-du-Rhône et du Vaucluse ont joué le jeu, en acceptant sur la base du volontariat de participer aux entretiens semi-directifs.Résultats : Les résultats qui sont ressortis de ces entretiens ont montré que le métier de sage-femme comportait plusieurs représentations : une profession médicale avec plusieurs compétences, une profession autour du nouveau-né, …Analyse et discussion : En comparant les résultats de l’étude avec ceux du travail de Marine Arthenay en 2012 , une évolution des représentations du métier de sage-femme, dans le sens d’une meilleure connaissance de cette profession a pu être constatée.Conclusion : Le métier de sage-femme, composé de femmes et d’hommes, est perçu par les patientes interrogées comme une profession médicale aux nombreuses compétences. En 2016, un élargissement des compétences ainsi qu’une campagne d’information ont eu lieu. On peut alors se demander l’impact qu’a cette campagne d’information sur la connaissance du métier de sage-femme, ainsi que l’avis des sages-femmes sur l’élargissement de leurs compétences