Search

The Monte Carlo method is widely used for the estimation of uncertainties in mechanical engineering design. However, while flexible, this method remains impractical in terms of computational time and scalability. To bypass these limitations, other more efficient approaches such as the Galerkin stochastic finite element method (GSFEM) or the collocation method have been proposed. GSFEM provides accurate output statistics, has the advantage of being sampling independent and can be modular in terms of operations, albeit code intrusive. While linear elasticity has been extensively covered in the literature, the application of GSFEM to nonlinear mechanical behaviour remains relatively unexplored, in part due to the difficulty to capture nonlinear effects with the traditional GSFEM interpolants. To this end, we propose a seamless and efficient modular framework avoiding the need to know a priori the material law. In particular, the method makes use of a wavelet based formulation able to capture simultaneously continuous and discontinuous behaviours, and stochastic operators are proposed to straightforwardly adapt any material model. Finally, the flexibility of this approach is illustrated with two problems: (i) a 3D hyperelastic example with nonlinear behaviour arising from buckling uncertainty, and (ii) the evaluation of the displacement of a point within a structure based on how much of the external accessible structural deformation is known.

A modular pipeline for improving the constitutive modelling of composite materials is proposed.The method is leveraged here for the development of subject-specific spatially-varying brain white matter mechanical properties. For this application, white matter microstructural information is extracted from diffusion magnetic resonance imaging (dMRI) scans, and used to generate hundreds of representative volume elements (RVEs) with randomly distributed fibre properties. By automatically running finite element analyses on these RVEs, stress-strain curves corresponding to multiple RVE-specific loading cases are produced. A mesoscopic constitutive model homogenising the RVEs’ behaviour is then calibrated for each RVE, producing a library of calibrated parameters against each set of RVE microstructural characteristics. Finally, a machine learning layer is implemented to predict the constitutive model parameters directly from any new microstructure. The results show that the methodology can predict calibrated mesoscopic material properties with high accuracy. More generally, the overall framework allows for the efficient simulation of the spatially-varying mechanical behaviour of composite materials when experimentally measured location-specific fibre geometrical characteristics are provided.

International audience; The first contractile waves in the developing embryonic gut are purely myogenic; they only involve smooth muscle. Here, we provide evidence for a transition from smooth muscle to interstitial cell of Cajal (ICC)-driven contractile waves in the developing chicken gut. In situ hybridization staining for anoctamin-1 (ANO1), a known ICC marker, shows that ICCs are already present throughout the gut, as from embryonic day (E)7. We devised a protocol to reveal ICC oscillatory and propagative calcium activity in embryonic gut whole mount and found that the first steady calcium oscillations in ICCs occur on (E14). We show that the activation of ICCs leads to an increase in contractile wave frequency, regularity, directionality, and velocity between E12 and E14. We finally demonstrate that application of the c-KIT antagonist imatinib mesylate in organ culture specifically depletes the ICC network and inhibits the transition to a regular rhythmic wave pattern. We compare our findings to existing results in the mouse and predict that a similar transition should take place in the human fetus between 12 and 14 wk of development. Together, our results point to an abrupt physiological transition from smooth muscle mesenchyme self-initiating waves to ICC-driven motility in the fetus and clarify the contribution of ICCs to the contractile wave pattern. NEW & NOTEWORTHY We reveal a sharp transition from smooth muscle to interstitial cell of Cajal (ICC)-driven motility in the chicken embryo, leading to higher-frequency, more rhythmic contractile waves. We predict the transition to happen between 12 and 14 embryonic wk in humans. We image for the first time the onset of ICC activity in an embryonic gut by calcium imaging. We show the first KIT and anoctamin-1 (ANO1) in situ hybridization micrographs in the embryonic chicken gut. Copyright © 2020 the American Physiological Society

Currently, the RA government is undertaking a number of measures in order to draw the agriculture in the republic out of unfavorable conditions, and to provide its future development which in its turn will help to increase the population.

Functional orthodontic trainer use depends on its various indications. It allows the interception of orthodontic malocclusions, the contributions are numerous

Autour des affrontements entre positions internalistes ou externalistes du jeu vidéo, il s’agit d’envisager la jouabilité au croisement de deux sens possibles. L’un, technique, s’attache à décrire la maniabilité du programme informatique pour son utilisateur. L’autre décrit la réalisation d’un état ludique entre la structure et le joueur. Notre analyse d’un jeu vidéo (Super Meat Boy) indique comment la maniabilité est créatrice d’espaces de jeux à investir pour le joueur. La fonction replay de ce jeu exemplifie les accumulations non linéaires qui constituent l’expérience de jeu. Dans ces itérations de parties se dessinent des brouillons qui témoignent de l’activité ludique. Cette génétique de la pratique vidéoludique permet de proposer une coïncidence de ces deux sens du jouable., Based on the arguments between internalist or externalist conceptions of video games, this paper considers « playability » at the crossroads of two possible meanings. A technical one, describing the software’s gameplay for its user. Another one depicting the making of a gaming state between the game’s structure and the player. The analysis of a video game (Super Meat Boy) shows how playability creates game spaces which the player can invest. The replay feature is a perfect example of the non-linear gathering of experiences that is gaming. In those iterations of game sessions drafts are appearing, witnesses to the gaming activity. This genetic approach of videogaming allows us to suppose a matching for the two different senses of « playability »., Interfaces numériques, 4(1), 2015

Sunflower oil is extensively used in frying in Algeria as an alternative to olive oil due to its low cost. However, the high level of unsaturated fatty acids (FA) contained in sunflower oil enhances its susceptibility to oxidation. In our study, the sunflower oil was heated at 99±2°C with incorporation of 9 L of oxygen/second for 52 h continuously in the absence of foodstuff. Heating polyunsaturated fatty acids (PUFAs) in the presence of air causes a greater degree of lipid peroxidation. The oil oxidation degree was monitored through several physicochemical analyses. The products of thermal oxidation were monitored using UV- spectrophotometric method and Fourier transform infrared spectroscopy (FT-IR). Compared to fresh oil, the free-fatty acid contents, peroxide value, density and moisture of the thermally oxidized sunflower oil increased. In addition, the iodine and saponification values decreased during thermal treatment. The treatment applied had a negative effect on FA composition; the most significant effects were on C18:2, C18:1 and C16:0 contents. Analysis of chromatographic profile of thermoxidized sunflower oil showed a reduction in linoleic acid (LA) and an increase in oleic and palmitic acids; decrease of linoleic acid content is used as an indicator of lipid oxidation. Moreover, during the early stages, conjugated dienes (CDs), absorbing at 233 nm, were formed upon decomposition of hydroperoxides. In our study, the early stages of lipid oxidation were measured by UV-spectrophotometric method. Hydroperoxides broke down into secondary products and were revealed by FT-IR; these scission products are generally odoriferous by nature. The C=O stretching band at 1739-1724 cm-1 of the aldehydes was much more intense. Formation of conjugated double bond systems and the isomerisation of cis to trans double bonds was observed in the C=C stretching region at 980 to 965 cm-1. The results obtained reveal that even fresh oil contains products of peroxidation and isomerization of C18:2, n-6; indeed, CDs can be produced during the refining process of oil. The treatment applied increased the rate of these products and conferred a marked rancid taste and a thick texture to the thermoxidized sunflower oil. Key words: Sunflower oil, Linoleic acid, thermally oxidative treatment, alteration level.

The present study deals with submerged ethanol, citric acid, and α-amylase fermentation by Saccharomyces cerevisiae SDB, Aspergillus niger ANSS-B5, and Candida guilliermondii CGL-A10, using date wastes as the basal fermentation medium. The physical and chemical parameters influencing the production of these metabolites were optimized. As for the ethanol production, the optimum yield obtained was 136.00 ± 0.66 g/l under optimum conditions of an incubation period of 72 h, inoculum content of 4% (w/v), sugars concentration of 180.0 g/l, and ammonium phosphate concentration of 1.0 g/l. Concerning citric acid production, the cumulative effect of temperature (30°C), sugars concentration of 150.0 g/l, methanol concentration of 3.0%, initial pH of 3.5, ammonium nitrate concentration of 2.5 g/l, and potassium phosphate concentration of 2.5 g/l during the fermentation process of date wastes syrup did increase the citric acid production to 98.42 ± 1.41 g/l. For the production of α-amylase, the obtained result shows that the presence of starch strongly induces the production of α-amylase with a maximum at 5.0 g/l. Among the various nitrogen sources tested, urea at 5.0 g/l gave the maximum biomass and α-amylase estimated at 5.76 ± 0.56 g/l and 2,304.19 ± 31.08 μmol/l/min, respectively after 72 h incubation at 30°C, with an initial pH of 6.0 and potassium phosphate concentration of 6.0 g/l.

Les techniques de négociation à base de systèmes multi-agent jouent un rôle très important dans les réseaux de radio cognitive, ils sont des méthodes utilisées pour résoudre le problème de l‘encombrement de spectre qui est l‘objet de notre PFE. Notre objectif dans le cadre de ce travail est donc de faire une petite synthèse entre deux protocoles qui sont les enchères et le contrat Net, ces protocoles sont définit par une séquence d‘actions entre l‘utilisateur primaire (PU) et les utilisateurs secondaires (SUs).

Materials with a periodically structured dielectric constant may exhibit forbidden photonic band gaps (PBG), that is, frequency domains where electromagnetic fields cannot propagate. The position and width of forbidden gaps can be controlled via the geometrical parameters of the structures and the contrast between the different permittivities. PBG materials have potential applications to a variety of devices in the microwave domain such as waveguides, couplers, reflectors and antenna substrate. This work reports on first experimental and theoretical studies of microwave guides and ring couplers based on PBG materials. Experiments are performed in the 27-75 GHz frequency range. Different coupling situations are given in illustration.

Dans le cadre de ce travail, nous avons essayé de synthétiser des informations bibliographiques essentielles sur une étude de la qualité physico-chimique et microbiologiques des eaux souterraines en générale. Ainsi que les normes internationales à respecter pour préserver cette denrée qui relève de l’avenir des générations futures. Car le siècle que nous vivons se repose sur la présence et l’utilisation rationnelle de l’eau.

Les graines de tomates sont les constituants majeurs des déchets de l’industrie de transformation des fruits de tomate, elles représentent 0,5%du poids du fruit et contiennent entre 18 et 30% de lipides sous forme d’huile. L’objet de ce travail est l’extraction et la caractérisation de l’huile de graine de tomate. Les graines de tomate proviennent d’un tas de déchet en stockage au niveau de la conserverie Ammour – Mouzaîa – Algérie. Après séparation, triage et séchage à l’air libre, les graines sont placées dans un dispositif Soxhelet contenant le n-hexane comme solvant d’extraction. Le rendement à l’extraction a été calculé, il est de 209,86 grammes d’huile pour 934,06grammes de graines de tomate, soit 22,47% ; après filtration le rendement est de 21,6%, soit 82%des lipides présent dans les graines de tomate. Les constantes physicochimiques caractéristiques de la qualité des huiles ont été mesurées avant et après raffinage de l’huile extraite ; il en ressort que le raffinage diminue l’acidité de 0,9 à 0,06%, la teneur en chlorophylle de 15,46 à 0,0092 ppm et entraine la disparition du phosphore. Les autres constantes mesurées n’ont pas subi de variation notable. Les résultats de l’analyse chromatographique de la fraction lipidique de l’huile de graines de tomate raffinée a révélé un profil chromatographique composé de 07 acides gras à 16 et 18 atomes de carbones. Les acides linoléiques et oléiques sont prédominants avec 52 et 22% respectivement. Les acides gras saturés sont représentés essentiellement par 13,18% d’acide palmitique et par de la résistance à l’oxydation de l’huile de graines de tomate extraite est de 4,70 heures à la température de 120°C, correspondant à une durabilité de 223 jours à 20°C.

Résumé Les infections respiratoires sont un problème de santé publique. Leur cause en est majoritairement virale chez le jeune enfant. La mise au point de techniques de détection par biologie moléculaire a permis d’en élargir le spectre virologique. L’objectif de notre travail est d’évaluer la corrélation entre les résultats des prélèvements effectués par aspiration rhinopharyngée et par lavage bronchoalvéolaire. Trente enfants présentant une symptomatologie d’infection respiratoire basse ont ainsi été prélevés aux deux sites au cours d’une même séance. Les échantillons ont été analysés par Polymerase chain reaction (PCR) virale multiplex (xTAG™ RVP). Une corrélation forte est retrouvée entre la positivité de la PCR virale dans les voies respiratoires hautes et basses (p = 0,0002). Le virus le plus fréquemment isolé est l’entéro-rhinovirus. Ces résultats confirment que l’infection virale touche l’appareil respiratoire de façon diffuse, et suggèrent que le prélèvement par aspiration rhinopharyngée suffit au diagnostic virologique d’une infection respiratoire virale basse chez l’enfant immunocompétent.

International audience; Whole blood samples from 211 stray cats from Algiers, Algeria, were cultured to detect the presence of Bartonella species and to evaluate the genetic diversity of B. henselae strains by multiple locus VNTR analysis (MLVA). Bartonella henselae was the only species isolated from 36 (17%) of 211 cats. B. henselae genotype I was the predominant genotype (64%). MLVA typing of 259 strains from 30 bacteremic cats revealed 52 different profiles as compared to only 3 profiles using MLST. Of these 52 profiles, 48 (92.3%) were identified for the first time. One-third of the cats harbored one MLVA profile only. As there was a correlation between the age of cats and the number of MLVA profiles, we hypothesized that the single profile in these cats was the profile of the initial infecting strain. Two-third of the cats harbored 2 to 6 MLVA profiles simultaneously. The similarity of MLVA profiles obtained from the same cat, neighbor-joining clustering and structure-neighbor clustering indicate that such a diversity likely results from two different mechanisms occurring either independently or simultaneously: independent infections and genetic drift from a primary strain.