A class of finite-element methods for singularly perturbed second-order differential equations

AbstractStandard Galerkin finite-element methods give poor accuracy when applied to second-order elliptic problems with a significant convective term. An upwind finite element was introduced to overcome this difficulty for constant-coefficient problems with zero-source term. This paper extends the use of this type of element to variable-coefficient problems with nonzero-source term by introducing a class of generalised upwind elements, called comparison-upwind finite elements. Two elements from this class are presented in detail. In this paper, we obtain nodal error estimates and global L1 and L2 error estimates for both methods. Finally, some numerical results are presented which demonstrate the methods' accuracy

Olfactory sensitivity of the marine flatfish Solea senegalensis to conspecific body fluids

Chemical communication is better understood in freshwater fish than marine fish. The Senegalese sole (Solea senegalensis) is a marine flatfish wherein one of the problems in aquaculture is the poor reproductive performance of hatchery-bred males. Is chemical communication involved in the reproduction of this species? Urine, intestinal fluid and mucus samples were taken from adult fish (wild-caught and hatchery-bred) over the spawning season (March-May), and assessed for olfactory potency using the electro-olfactogram (EOG). The effect of stimulation of the olfactory system with adult female urine on circulating luteinizing hormone (LH) levels was also tested in males. Intestinal fluid and urine were potent olfactory stimuli for both juvenile and adult conspecifics, evoking large-amplitude, concentration-dependent EOG responses, with thresholds of detection at approximately 1:10(6). However, the amplitude of the response to urine depended on the sex and state of maturity of both the donor and the receiver. Most olfactory activity could be extracted by C18 solid-phase cartridges. Urine from mature females evoked a slight, but significant, increase in circulating LH levels in mature males 30 min after exposure. Furthermore, the olfactory potency of urine differed between wild-caught and hatchery-bred fish; however, contrary to expectations, urine from wild-caught females was less potent than that from hatchery-bred females. Taken together, these results strongly suggest that faeces-and urine-released odorants are involved in reproduction in the Senegalese sole, and establish a basis for further investigation into pheromonal communication in marine teleosts.Instituto Nacional de Investigacion y Tecnologia Agraria y Alimentaria; EU through FEDER [RTA2011-00050, RTA2014-00048]; Ministerio de Economia y Competitividad (MINECO) [AGL2013-41196-R, RTA2013-00023-C02-01]; FPI-INIA - MINECO, Spain; Fundacao para a Ciencia e a Tecnologia (Foundation for Science and Technology, Portugal) [UID/Multi/04326/2013]info:eu-repo/semantics/publishedVersio

Les référentiels en formation

Cet article aborde les référentiels en formation comme éléments de la régulation sociale normative qui s’opère entre différents champs d’activités contribuant à la formation. Les référentiels émergent dans un contexte de redéfinition des rôles des acteurs concernés par la formation et coïncident avec une évolution sociétale où la confiance est constamment à construire. Les référentiels constituent la formalisation provisoire d’accords sur des attendus relatifs aux activités engagées dans le champ de la formation et peuvent, à certaines conditions, contribuer à générer de la confiance.This paper tackles systems of reference in training as elements of the normative social regulation which is at work between different fields of activity contributing to the training. These reference systems emerge in a context of redefinition of the training actors’ roles and coincide with a societal evolution in which trust is constantly to be constructed. Reference systems are constituted by the temporary formalization of agreements on grounds relating to activities started in the training field and can contribute to generate some trust on certain conditions.Este artículo aborda los referenciales durante la formación como elementos de la regulación social normativa que se opera entre diferentes campos de actividades contribuyentes à la formación. Los referenciales emergen en un contexto de nueva definición de los papeles de los protagonistas concernidos por la formación y coinciden con una evolución “societal“ en la que la confianza está constantemente por construir. Los referenciales constituyen la formalización provisional de acuerdos sobre expectativas relativas a actividades iniciadas en el ámbito de la formación y pueden, en ciertas condiciones, contribuir à generar confianza.Dieser Artikel betrachtet die Bezugssyteme bei der Ausbildung als Elemente der normativen sozialen Regulierung, die zwischen verschiedenen Tätigkeitsfeldern, die zur Ausbildung beitragen, stattfinden. Die Bezugssysteme kommen in einem Kontext von Neudefinition von den Rollen der Akteure auf, die von der Ausbildung betroffen werden und kongruieren mit einer sozietalen Entwicklung zusammen, wo das Vertrauen ständig zu erarbeiten ist. Die Bezugssysteme stellen eine vorläufige Formalisierung von Absprachen dar, was bei den Tätigkeiten im Ausbildungsfeld erwartet wird, und können unter bestimmten Bedingungen dazu beitragen, Vertrauen zu erzeugen

Role of Ion Channels in the Maintenance of Sperm Motility and Swimming Behavior in a Marine Teleost

In oviparous marine fishes, the hyperosmotic induction of sperm motility in seawater (SW) is well established, however, the potential function of ion channels in the maintenance of post activated spermatozoon swimming performance remains largely unknown. Here, we investigated the influence of ion channels on the spermatozoon swimming parameters using the gilthead seabream (Sparus aurata) as a model for modern marine teleosts. Our data show that the SW-induced activation of seabream sperm motility requires three concomitant processes, the hyperosmotic shock, an ion-flux independent increase of the intracellular concentration of Ca2+ ([Ca2+]i), but not of [K+]i or [Na+]i, and the alkalization of the cytosol. The combination of all three processes is obligatory to trigger flagellar beating. However, the time-course monitoring of sperm motion kinetics and changes in the [Ca2+]i, [K+]i and [Na+]i in SW or in non-ionic activation media, showed that the post activated maintenance of spermatozoa motility is dependent on extracellular Ca2+ and K+. A meta-analysis of a seabream sperm transcriptome uncovered the expression of multiple ion channels, some of which were immunolocalized in the head and/or tail of the spermatozoon. Selective pharmacological inhibition of these ion channel families impaired the long-term motility, progressivity, and velocity of SW-activated spermatozoa. The data further revealed that some antagonists of K+-selective or Ca2+-selective channels, as well as of stretch-activated and mechanosensitive channels, altered the trajectory of spermatozoa, suggesting that these ion channels are likely involved in the control of the swimming pattern of the post activated spermatozoon. These combined findings provide new insight into the signaling pathways regulating spermatozoon activation and swimming performance in marine fishes.info:eu-repo/semantics/publishedVersio

Broussal, D., Marcel, J.-F. et Thievenaz, J. (dir.) (2016). Soigner et former, contribution des sciences de l’éducation

Les restructurations en cours depuis quelques années dans le champ de la santé, touchant notamment l’organisation des soins ou les formations des professions paramédicales, ont amené des soignants, des cadres ou des formateurs de ce secteur à se tourner vers les sciences de l’éducation afin de trouver des éclairages et des soutiens pour interroger et accompagner les changements en cours. En retour, cet investissement des sciences de l’éducation dans le champ de la santé fut l’occasion d’une p..

Les référentiels en formation : enjeux, légitimité, contenu et usage

Ce ne sont pas, de nos jours, les références aux référentiels qui manquent dans les champs de l’éducation et de la formation ! Aux référentiels de métier, de diplôme, sont venus s’ajouter les référentiels de compétences, de formation, de validation, voire de situations. Ils servent à la conception, à la planification, au pilotage et à l’évaluation des formations. N’oublions pas, non plus, les référentiels de qualité qui portent sur la formation ou les dispositifs de formation. Aux yeux de Fig..

Weakly non linear modeling of submerged wave energy converters

International audienceWave-to-Wire numerical models being developed for the study of wave energy converters usually make use of linear potential flow theory [[1], [2], [3], [4], [5]] to describe wave-structure interaction. This theory is highly efficient from a computational perspective. However, it relies on assumptions of small wave steepness and small amplitude of motion around mean positions. Often, maximization of wave energy converters’ energy performance implies large amplitude motion [[6], [7], [8]], thus contradicting the assumption of small amplitude motion.An alternative approach is to linearize the free surface conditions on the instantaneous incident wave elevation (Weak-Scatterer approach [9]) while the body conditions are evaluated at the exact body position. Studies of wave energy converters’ dynamic response using this method are expected to be more accurate, while maintaining a reasonable computational time. With this aim, a Weak-Scatterer code (CN_WSC) was developed and used to study two submerged wave energy converters. The first is a heaving submerged sphere and the second is a bottom-hinged fully submerged oscillating flap. They are inspired respectively by the Ceto [10] and WaveRoller [11] devices.Initial calculations were performed in linear conditions first to verify the CN_WSC against linear theory. Subsequently, calculations in nonlinear conditions were performed, using large wave steepness and amplitude of body motion. In linear conditions, results of CN_WSC showed good agreement with linear theory, whereas significant deviations from linear theory were observed in nonlinear conditions. As amplitude of body motion increases, linear theory tends to overestimate energy performance in comparison with Weak-Scatterer theory. In contrast, with smaller amplitude of motion but larger wave steepness, the opposite result is obtained: energy performance is underestimated by linear theory compared to Weak-Scatterer theory

Neurohypophysial and paracrine vasopressinergic signaling regulates aquaporin trafficking to hydrate marine teleost oocytes

The dual aquaporin (Aqp1ab1/Aqp1ab2)-mediated hydration of marine teleost eggs, which occurs during oocyte meiosis resumption (maturation), is considered a key adaptation underpinning their evolutionary success in the oceans. However, the endocrine signals controlling this mechanism are almost unknown. Here, we investigated whether the nonapeptides arginine vasopressin (Avp, formerly vasotocin) and oxytocin (Oxt, formerly isotocin) are involved in marine teleost oocyte hydration using the gilthead seabream (Sparus aurata) as a model. We show that concomitant with an increased systemic production of Avp and Oxt, the nonapeptides are also produced and accumulated locally in the ovarian follicles during oocyte maturation and hydration. Functional characterization of representative Avp and Oxt receptor subtypes indicates that Avpr1aa and Oxtrb, expressed in the postvitellogenic oocyte, activate phospholipase C and protein kinase C pathways, while Avpr2aa, which is highly expressed in the oocyte and in the follicular theca and granulosa cells, activates the cAMP-protein kinase A (PKA) cascade. Using ex vivo, in vitro and mutagenesis approaches, we determined that Avpr2aa plays a major role in the PKA-mediated phosphorylation of the aquaporin subdomains driving membrane insertion of Aqp1ab2 in the theca and granulosa cells, and of Aqp1ab1 and Aqp1ab2 in the distal and proximal regions of the oocyte microvilli, respectively. The data further indicate that luteinizing hormone, which surges during oocyte maturation, induces the synthesis of Avp in the granulosa cells via progestin production and the nuclear progestin receptor. Collectively, our data suggest that both the neurohypophysial and paracrine vasopressinergic systems integrate to differentially regulate the trafficking of the Aqp1ab-type paralogs via a common Avp-Avpr2aa-PKA pathway to avoid competitive occupancy of the same plasma membrane space and maximize water influx during oocyte hydration

L’approche par compétences : un nouveau paradigme pour la pédagogie universitaire ?

Au cours des deux dernières décennies, l’approche par compétences a pénétré le monde universitaire, non sans y susciter de nouveaux enjeux et y introduire un débat entre partisans et adversaires de cette approche. Des pratiques pédagogiques nouvelles ont ainsi vu le jour, notamment autour de la professionnalisation, dont on dégage dans ce texte quelques principes utiles. Toutefois cet article vise, avant tout, à montrer l’importance d’un détour théorique s’appuyant sur différents travaux scientifiques afin de construire un modèle de la compétence qui puisse éclairer l’intervention pédagogique. Il s’agit alors de montrer en quoi une approche par compétences, ainsi outillée, permet d’imaginer de nouvelles pratiques.For the last two decades, competency-based approach has entered college not without creating new stakes and sparking a debate between supporters of and opposers to such an approach. New teaching practices were developed like for instance around professionalization, for which the text gives several useful principles. Nevertheless this article aims above all at showing how important theory is when based on different scientific works in order to construct a model of competence that can throw light on teaching interventions. The idea is therefore to show how competency-based approach with such tools can help create new practices.A lo largo de los dos últimos decenios, el aprendizaje por capacidades entró en el mundo universitario, no sin suscitar nuevos impulsos y encender un debate entre partidarios y adversarios de este nuevo método. Unas prácticas pedagógicas nuevas irrumpieron, sobre todo en torno a la profesionalización, de las que se sacan en este texto algunos principios útiles. Sin embargo la meta de este artículo, ante todo, es enseñar la importancia de un enfoque teórico que se apoye sobre diferentes trabajos científicos para construir un modelo de la competencia que pueda alumbrar la intervención pedagógica. Se trata pues de enseñar en qué medida el aprendizaje por capacidades permite imaginar prácticas innovadoras.Im Laufe der letzten beiden Jahrzehnte ist die kompetenzbasierte Herangehensweise in die Universität eingedrungen und hat dabei neue Schwerpunkte gesetzt und eine Debatte zwischen Befürwortern und Gegnern dieser Methode hervorgerufen. Neue pädagogische Praktiken sind somit zum Vorschein gekommen, insbesondere was die Professionalisiserung angeht, von daher werden in diesem Text einige nützliche Prinzipien herausgearbeitet. Dennoch zielt unsere Arbeit darauf ab, die Bedeutung eines theoretischen Umwegs zu zeigen, der auf verschiedenen wissenschaftlichen Arbeiten beruht, um ein Modell der Kompentenz herauszuarbeiten, das die pädagogischen Beiträge aufklären kann. Dann geht es darum zu zeigen, in wie fern eine kompentenzbasierte Herangehensweise neue Praktiken fördern kann