Academic literature on the topic 'Jeux du cycle impair'

Zika virus (ZIKV) is a highly transmissive virus that belongs to the Flaviviridae family, which comprises several other pathogens that threaten human health. This re-emerging virus gained attention during the outbreak in Brazil in 2016, where a considerable number of microcephaly cases in newborns was associated with ZIKV infection during pregnancy. Lacking a preventive vaccine or antiviral drugs, efforts have been made to better understand the viral life cycle. In light of this, the relevance of the endosomal–lysosomal compartment for the ZIKV life cycle was investigated. A549 and SH-SY5Y cells were infected with either the African strain (associated with mild symptoms) or the French Polynesia strain (associated with neurological complications). For both strains, the V-ATPase inhibitor, bafilomycin A1, efficiently inhibited ZIKV entry and prevented the spread of the infection by interfering with viral maturation. Additionally, affecting cholesterol metabolism and transport with the drug U18666A, which inactivates late endosomes and lysosomes, impairs the viral life cycle. The data presented show a clear antiviral effect of two compounds that target the same compartments in different ways. This highlights the relevance of the endosomal–lysosomal compartment for the viral life cycle that should be considered as a target for antivirals.

Sepsis has been reported to cause mitochondrial dysfunction and inhibition of key enzymes that regulate the tricarboxylic acid (TCA) cycle. We investigated the effect of sepsis on high-energy phosphates, glycolytic and TCA cycle intermediates, and specific amino acids that are involved in regulating the size of the TCA cycle pool during changes in metabolic state of the heart. Sepsis was induced in 12 female rats by the cecal ligation and perforation technique under halothane anesthesia; seven control rats underwent cecal manipulation without ligation. At 36-42 h postsurgery, the rats were reanesthetized, the chest was opened, and the hearts were freeze-clamped. Perchloric acid extracts of the hearts were analyzed with fluorometric enzymatic methods and 31P nuclear magnetic resonance spectroscopy. There were no significant differences in the levels of the TCA cycle intermediates or high-energy phosphates between the septic and control rats. The major metabolic changes were the 28% decrease in alanine and the 31% decrease in glutamate in the septic hearts compared with control (P less than 0.05 and P less than 0.005, respectively). Phosphocholine, a component of membrane phospholipids, was increased by 91% in the septic hearts (P less than 0.01). We conclude that sepsis does not impair the TCA cycle or induce significant cellular ischemia in the heart. The increase in phosphocholine may represent significant cellular membrane disruption during sepsis.

Objectif : L’essai a visé à développer de nouvelles initiatives de gestion de la fertilité des sols compatibles avec la gestion rationnelle des ressources mises en jeux afin d’évaluer et d’apprécier l’efficacité des différentes combinaisons d’engrais sur le rendement de la laitue et d’identifier le meilleur model d’amélioration des conditions de culture de cette plante. Méthodologie et résultats : Au cours de l’essai, le dispositif expérimental adopté a été celui en blocs aléatoire complet à quatre traitements et à trois répétitions. Les traitements utilisés ont été : T0 (témoin absolu sans apport de fertilisants), T1 (16 t.ha-1 de fumier de bovin +150 Kg.ha-1 de NPK :15-15-15 +50 Kg.ha-1 d’Urée), T2 (16 t.ha-1 de fiente de volailles + 150 Kg.ha-1 de NPK :15-15-15 +50 Kg.ha-1 d’Urée) et T3 (16 t.ha-1 d’un mélange équitable de fientes de volailles et de fumier de bovin +150 Kg.ha-1 de NPK :15- 15-15 +50 Kg.ha-1 d’Urée). Les résultats obtenus ont montré que le traitement T2 a amélioré le rendement de la laitue qui a dépassé le témoin de 134%. Conclusion et application de résultats : L’étude a consisté à faire une évaluation de l’impact de différentes combinaisons d’engrais organiques et minéraux sur la productivité de la laitue. Les résultats obtenus ont monté que le traitement T2 suivi du traitement T3 puis du traitement T1 ayant donné respectivement un surplus de produit de 134,00%, 75,69% et de 62,16% par rapport au traitement témoin T0. La laitue étant une plante à cycle court, l’utilisation du fumier, à base de fientes de volailles, riche en azote dont la libération est rapide, serait mieux indiquée pour sa culture en plein champ et surtout en maraîchage. Mots clés : laitue, fertilisation, combinaison, rendement Tchaniley et al., J. Appl. Biosci. 2020 Effet de la combinaison des fertilisants organiques et minéraux (NPK 15-15- 15 et urée) sur le rendement de la laitue (Lactuca sativa L.) dans le sud du Togo. 15541 Effect of the combination of organic and mineral fertilizers (NPK 15-15-15 and urea) on the yield of lettuce (Lactuca sativa L.) in southern Togo ABSTRACT Objective: The aim of the trial was to develop new soil fertility management initiatives compatible with the rational management of the resources involved in order to assess and assess the effectiveness of the different combinations of fertilizers on the yield of lettuce and to identify the best model for improving the growing conditions of this plant. Methodology and results: During the test, the experimental device adopted was that in complete random blocks with four treatments and three repetitions. The treatments used were: T0 (absolute control without addition of fertilizers), T1 (16 t.ha-1 of bovine manure +150 Kg.ha-1 of NPK: 15-15-15 +50 Kg.ha-1 of Urea), T2 (16 t.ha-1 of poultry droppings + 150 Kg.ha-1 of NPK: 15-15-15 +50 Kg.ha-1 of Urea) and T3 (16 t.ha -1 of a fair mix of poultry droppings and bovine manure +150 Kg.ha-1 of NPK: 15-15-15 +50 Kg.ha-1 of Urea). The results obtained showed that the T2 treatment improved the yield of the lettuce, which exceeded the control by 134%. Conclusion and application of results: The study consisted of assessing the impact of different combinations of organic and mineral fertilizers on the productivity of lettuce. The results obtained showed that the T2 treatment followed by the T3 treatment then by the T1 treatment having given respectively a surplus of product of 134.00%, 75.69% and 62.16% compared to the control treatment T0. Since lettuce is a short-cycle plant, the use of manure, based on poultry droppings, rich in nitrogen and quick to release, would be better suited for its cultivation in the open field and especially in market gardening. Keywords: lettuce, fertilization, combination, yield

Trypanosoma cruzi is the aetiologic agent of Chagas disease, which affects people in the Americas and worldwide. The parasite has a complex life cycle that alternates among mammalian hosts and insect vectors. During its life cycle, T. cruzi passes through different environments and faces nutrient shortages. It has been established that amino acids, such as proline, histidine, alanine, and glutamate, are crucial to T. cruzi survival. Recently, we described that T. cruzi can biosynthesize glutamine from glutamate and/or obtain it from the extracellular environment, and the role of glutamine in energetic metabolism and metacyclogenesis was demonstrated. In this study, we analysed the effect of glutamine analogues on the parasite life cycle. Here, we show that glutamine analogues impair cell proliferation, the developmental cycle during the infection of mammalian host cells and metacyclogenesis. Taken together, these results show that glutamine is an important metabolite for T. cruzi survival and suggest that glutamine analogues can be used as scaffolds for the development of new trypanocidal drugs. These data also reinforce the supposition that glutamine metabolism is an unexplored possible therapeutic target.

Hypoxia has been associated with multiple sclerosis (MS) and is an important area of research. Hypoxia can exacerbate inflammation via the prolylhydroxylase pathway. Inflammation can also trigger hypoxia by damaging mitochondria and endothelial cells to impair blood flow regulation. We hypothesize that there is a “hypoxia–inflammation cycle” in MS which plays an important role in MS disease progression. Therapies that break this cycle may be an interesting area of exploration for treatment of MS.

The purpose of this investigation was to examine the effects of moderate hypohydration (HY) on skeletal muscle glycogen resynthesis after exhaustive exercise. On two occasions, eight males completed 2 h of intermittent cycle ergometer exercise (4 bouts of 17 min at 60% and 3 min at 80% of maximal O2 consumption/10 min rest) to reduce muscle glycogen concentrations (control values 711 +/- 41 mumol/g dry wt). During one trial, cycle exercise was followed by several hours of light upper body exercise in the heat without fluid replacement to induce HY (-5% body wt); in the second trial, sufficient water was ingested during the upper body exercise and heat exposure to maintain euhydration (EU). In both trials, 400 g of carbohydrate were ingested at the completion of exercise and followed by 15 h of rest while the desired hydration level was maintained. Muscle biopsy samples were obtained from the vastus lateralis immediately after intermittent cycle exercise (T1) and after 15 h of rest (T2). During the HY trial, the muscle water content was lower (P less than 0.05) at T1 and T2 (288 +/- 9 and 265 +/- 5 ml/100 g dry wt, respectively; NS) than during EU (313 +/- 8 and 301 +/- 4 ml/100 g dry wt, respectively; NS). Muscle glycogen concentration was not significantly different during EU and HY at T1 (200 +/- 35 vs. 251 +/- 50 mumol/g dry wt) or T2 (452 +/- 34 vs. 491 +/- 35 mumol/g dry wt). These data indicate that, despite reduced water content during the first 15 h after heavy exercise, skeletal muscle glycogen resynthesis is not impaired.

Harry Potter, succès d’édition sans précédent, est une œuvre hybride et intertextuelle, héritière de nombreuses traditions littéraires. A l’influence des genres de l’imaginaire s’ajoute celle du roman scolaire, du récit de mystère ou d’aventures et celle du texte initiatique. De cette intergénéricité naît un univers riche, foisonnant de trouvailles dont l’écrit et ses instruments proposent de multiples exemples. L’auteure met ainsi en place moult jeux d’imitation et de détournement autour de scènes de lecture et d’écriture, reflétant la richesse de ses romans. Elle propose en outre à son lecteur, par une écriture ludique et manipulatrice, de nombreux jeux, sollicitant tantôt son esprit de déduction et sa mémoire, tantôt sa culture littéraire. Elle multiplie en effet les clins d’œil et références à d’autres œuvres dans son texte dont la lecture peut se faire à plusieurs niveaux. Fidèle à la tradition du cycle en littérature, la romancière a prolongé son univers de fiction dans de nouveaux écrits, dans une logique de pratique transfictionnelle. A l’initiative de l’écrivain ou de ses lecteurs qui se sont pris au jeu, le monde de Harry Potter s’est déployé sur d’autres médias, dans une suite de réécritures à ce jour ininterrompue, faisant de ces textes une fiction transmédiatique. Cette thèse s’articule autour des trois grands axes évoqués, à savoir la place et le rôle de l’écrit dans les Harry Potter puis la relation qui se noue entre la romancière et son lecteur grâce à ses jeux d’écriture et ensuite aux très nombreuses réécritures du cycle
The Harry Potter books are the inheritors of several literary traditions. Both intergeneric and intertextual, they do not only belong to the category of non-realistic genres but also to the traditions of school fiction, mystery or adventure novels and initiation stories. This hybridity results in the creation of a very rich universe, teeming with inventions; all sorts of texts and writing tools are representative of this creativity. J. K. Rowling both imitates and distorts her sources, in scenes in which writing and reading play an important part. Besides, thanks to a playful and manipulative style, she invites her readers to play with their sense of deduction and memory and their literary culture. Indeed, she refers to many works of fiction and thus, proposes different ways of reading and understanding her stories. As is the case with most literary cycles, she has expanded on her fictional world in new texts, pieces of what is now called “trans-fictional” writing. J. K. Rowling and her readers also have developed the Harry Potter world, rewritten it and transferred it to new media, turning this literary work into transmedia fiction. This study focuses on the three main points mentioned, that is to say first on the part played by reading and writing in the Harry Potter books, then on the relation between the writer and her readers through her writing and on the many different ways in which the novels have been and still are being rewritten

A partir de l'analyse d'un dispositif d'Atelier de géométrie en cycle 3, cette thèse montre comment les « jeux de langage » produits par la résolution de situations problématiques sur les solides peuvent favoriser la construction par les élèves de nouvelles connaissances relatives à un vocabulaire de géométrie spécifique.
Grâce à l'élaboration d'une méthodologie originale d'analyse des gestes de l'enseignant, cette recherche propose également de rendre compte du rôle et de la place de l'enseignant dans de telles interactions langagières. Pour ce faire, nous proposons d'expliciter ses modalités effectives d'intervention puis de modéliser son action en situation en termes de tutelle et de médiation.

Cette thèse présente une étude qualitative sur les affordances d'un jeu sérieux éducatif (JSÉ) pour l'apprentissage de l'anglais langue seconde (ALS) dans un contexte formel de classe. Les affordances pour l'apprentissage réfèrent aux possibilités d'action offertes par un jeu numérique pour apprendre une langue seconde aux apprenants-joueurs capables de les percevoir. L'étude des affordances des jeux numériques s'avère utile pour identifier les composantes du jeu pouvant soutenir l'apprentissage du point de vue des apprenants-joueurs, ce qui est peu documenté dans la littérature scientifique. D'ailleurs, identifier les composantes du jeu soutenant l'apprentissage s'avère utile pour (1) soutenir les décisions relatives à la conception des JSÉ afin d'optimiser leur potentiel pédagogique et (2) pour appuyer le choix du JSÉ comme outil pédagogique pour l'apprentissage dans un contexte d'éducation formelle similaire. Pourtant, peu d'études se sont penchées sur l'étude des affordances des jeux numériques pour l'apprentissage de l'ALS dans la littérature scientifique. Au meilleur de notre connaissance, aucune étude n'a ciblé l'identification des affordances dans un JSÉ conçu spécifiquement pour l'apprentissage de l'ALS. Les résultats de notre recherche s'adressent aux professionnels de la conception de jeux numériques pour l'apprentissage, aux compagnies de JSÉ, aux enseignants qui sélectionnent le matériel pédagogique pour leurs cours et à tous les professionnels de l'éducation qui conçoivent des formations et des interventions pédagogiques basées sur le jeu numérique. Les assises théoriques de notre étude relèvent de la deuxième génération de la théorie de l'activité (TA) et du concept d'affordance. Les concepts activité, médiation, et agentivité nous permettent de caractériser notre modèle d'étude étant donné que nous nous y sommes appuyés pour étudier les interactions des apprenants-joueurs avec le JSÉ en fonction de leurs intentions ou objets; pour étudier les JSÉ comme artefacts médiateurs de l'apprentissage et du divertissement; ainsi que pour tenir compte des aspects contextuels qui pourraient influencer l'activité dans le jeu des apprenants-joueurs. Afin de répondre à nos questions de recherche, nous avons collecté des données auprès des participants par plusieurs moyens dont des questionnaires, des entrevues semi-dirigées, des rapports de réflexion et des traces numériques relatives à chaque séance de jeu. Nous avons analysé l'activité dans le jeu des quatre étudiantes universitaires de premier cycle, inscrites dans un cours d'ALS et sélectionnées en fonction de leur expérience à jouer à des jeux numériques et leur niveau d'anglais. Cette analyse fut inspirée par les travaux de Reeves et al., (2017) sur les niveaux d'analyse ethnométhodologique des jeux. Dans le cadre de cette étude, l'activité dans le jeu comporte (1) les actions menées par les participantes hors du monde virtuel du jeu mais inscrites au niveau de la classe dans la salle de cours, (2) les interactions des apprenants-joueurs avec le JSÉ à l'écran et (3) la perception des participantes à l'égard du JSÉ. Ainsi, à partir de la perception des étudiants universitaires et des traces numériques de leur activité dans le jeu, nous avons identifié huit affordances perçues qui mobilisent des connaissances linguistiques, sociolinguistiques, discursives et langagières : (1) apprendre de nouveaux mots, (2) prononcer les mots en anglais, (3) percevoir la structure grammaticale, (4) communiquer des messages appropriés selon le contexte, (5) s'entraîner pour communiquer dans la vie réelle, (6) organiser des mots et phrases pour communiquer et agir, (7) s'entraîner en compréhension orale, et (8) s'entraîner en compréhension orale et écrite. Dans cette thèse, les affordances perçues réfèrent aux possibilités pour apprendre l'anglais langue seconde remarquées par les étudiants Cinq sur les huit affordances perçues constituent des affordances réelles, c'est-à-dire, des possibilités pour apprendre l'ALS remarquées et utilisées par les participantes lors de l'activité de jeu: (1) apprendre des nouveaux mots; (2) communiquer des messages appropriés selon le contexte; (3) organiser des mots et des phrases pour communiquer et agir; (4) s'entraîner en compréhension orale; et (5) s'entraîner en compréhension de l'oral et l'écrit de manière intégrée. Les affordances réelles ont été déclarées par les participantes et peuvent être identifiées sur les traces numériques. Trois affordances perçues n'ont pas été identifiées sur les traces numériques pour des raisons méthodologiques: (1) prononcer les mots en anglais, (2) percevoir la structure grammaticale, et (3) s'entraîner pour communiquer dans la vie réelle. Les affordances pour l'apprentissage de l‘ALS identifiées dans le cadre de cette thèse sont associées à des composantes du jeu spécifiques, dont quatre mécaniques du jeu principales et dix-sept objets numériques du jeu (ONJ). Il ressort de cette étude que l'expérience des participantes à jouer à des jeux numériques semble exercer une influence plus forte sur la perception d'affordances pour l'apprentissage de l'ALS que le niveau d'anglais déclaré. Les résultats de cette étude soulèvent le besoin de l'accompagnement pédagogique de la part du professeur durant et à la suite d'une activité basée sur le jeu dans un contexte formel de classe afin de focaliser l'attention des étudiants sur le contenu linguistique et d'éviter la fossilisation de vocabulaire incorrect. Par ailleurs, nous apportons une série de recommandations pour soutenir la conception de jeux numériques pour l'apprentissage des langues secondes.
This thesis presents a qualitative study on the affordances of an educational serious game (ESG) for learning English as a second language (ESL) in a formal classroom setting. Learning affordances refer to the action possibilities offered by a digital game for learning a second language to student-players who can perceive them. The study of digital game affordances is useful for identifying game components that can support learning from the perspective of student-players, which is not well documented in the scientific literature. In fact, identifying game components that support learning could be useful to (1) inform game design decisions when creating games for educational purposes and (2) to inform the selection of ESGs as a pedagogical tool for learning in formal educational settings. Yet, few scientific studies have examined the affordances of digital games for ESL learning. To the best of our knowledge, no study has focused on identifying affordances in an ESG designed specifically for ESL learning. Our findings are relevant to game designers of ESGs, videogame companies creating ESGs, teachers selecting games as instructional materials for their courses, and all educators designing digital game-based interventions. The theoretical framework of our study is based in the second generation of activity theory (AT) and the concept of affordance. In particular, the concepts of activity, mediation, and agentivity characterize our approach to study student-players' interactions with an ESG based on their intentions or objects; to study ESGs as mediating artifacts of learning and entertainment; and to consider contextual aspects that might influence activity in learner-players' play. Data was collected from participants through a variety of instruments including questionnaires, semi-structured interviews, reflection reports, and digital traces of 2 gaming sessions. We analyzed the gaming activity of four undergraduate students enrolled in an ESL course and selected based on their experience playing digital games and their proficiency level of English. This analysis was inspired by the work of Reeves et al., (2017) on ethno-methodological analysis of games. It included (1) participants' actions in the classroom, (2) student-players' interactions with the ESG on screen and (3) participants' perceptions of the ESG. Thus, based on the analysis of students' perceptions and digital traces of their gaming activity, we identified eight perceived affordances that mobilize linguistic, socio-cultural, discursive and language knowledge : (1) learning new words, (2) pronouncing words in English, (3) perceiving grammatical structure, (4) communicating messages appropriate to the context, (5) practicing communication in real life, (6) organizing words and phrases to communicate and act, (7) practicing listening comprehension, and (8) practicing listening and reading comprehension. Perceived affordances refer to the opportunities for learning English as a second language noticed by the students. Five of the eight perceived affordances were coded as real affordances, that is, affordances that are perceived and used by participants as documented in digital traces: (1) learning new words; (2) communicating context-appropriate messages; (3) organizing words and phrases for communication and action; (4) practicing listening comprehension; and (5) practicing listening and reading comprehension in an integrated manner. Three perceived affordances were not identified on the digital traces for methodological reasons: (1) pronouncing words in English, (2) perceiving grammatical structure, and (3) practicing communication in real life. The affordances for learning ESL are associated with specific game components, including 4 chore game mechanics and 17 digital game objects (DGO). Our findings indicate that participants' experience playing digital games had a stronger influence on the perception of affordances for learning than their declared English language proficiency level. The results of this study highlight the need for pedagogical support from the teacher during and after a game-based activity in a classroom setting in order to focus students' attention on language content and avoid the fossilization of incorrect vocabulary. In addition, we provide a series of recommendations to support the design of digital games for second language learning.

Peu d’études s’intéressent aux habitudes de jeu des enfants. En 1996, Ladouceur, Ferland, Jacques, et Boudreault notent que 4,5% des enfant âgés de 9 à 12 ans montrent les caractéristiques du jeu pathologique. Ceci constitue un taux deux fois plus élevé que chez les adultes. Réalisée auprès de 84 élèves du primaire, la présente étude examine la compréhension du questionnaire employé par ces chercheurs, soit le South Oaks Gambling Screen-Adolescent Version (SOGS-RA, Winters, Stinchfîeld, & Fulkerson, 1993). Les résultats de cette étude indiquent que près d’une question sur trois est incomprise. Plus le score au SOGS-RA est élevé, moins la compréhension du questionnaire est bonne. Cependant, la compréhension n’est pas reliée au niveau de scolarité. Des explications favorisent une diminution des scores lors d’une seconde passation. La discussion souligne les implications pratiques et théoriques de ces résultats et offre des suggestions pour l’élaboration d’un nouvel instrument de mesure.

La thèse se compose de trois parties dont les deux premières se rattachent à la théorie des jeux et la troisième à la biologie théorique. La première partie est consacrée à l'étude des équilibres corrélés. Après avoir étudié les propriétés de la techique de réduction duale et développé ses applications, nous utilisons cette technique pour montrer que l'ensemble des jeux ayant un unique équilibre corrélé est ouvert, ce qui n'est pas vrai des équilibres de Nash, et pour caractériser la classe des jeux dont le polytope des équilibres corrélés contient un équilibre de Nash dans son intérieur relatif. Cette classe étend et généralise celle des jeux à somme nulle. Deux autres contributions sont également présentées.

La deuxième partie est consacrée aux jeux d'évolution, et étudie le lien entre l'issue de processus évolutifs et les concepts stratégiques statiques. Nous montrons notamment que les dynamiques d'évolution peuvent éliminer toutes les stratégies appartennant au support d'au moins un équilibre corrélé, et ce pour n'importe quelle dynamique monotone et pour des ensembles ouverts de jeux et de conditions initiales. L'élimination de toutes les stratégies dans le support des équilibres de Nash se produit sous toutes les dynamiques d'adaptation myope régulières et, sous la dynamique des réplicateurs ou la dynamique de meilleure réponse, à partir de presque toutes les conditions initiales.

La troisième partie, co-écrite, étudie les déterminants de la séparation entre lignée germinale et lignée somatique chez les algues vertes volvocales.

La communication en milieu didactique est une spécification de la communication humaine. La théorie de l'action conjointe en didactique (TACD), développée par Sensevy, Mercier & al.(2005, 2007 et 2008), considère la production des discours du professeur et des élèves comme la manifestation de transactions didactiques dont le savoir est l'objet transactionnel. Ces transactions permettent à la fois la reconnaissance mutuelle des interlocuteurs et la participation à un jeu conjoint, qui consiste à construire et changer le monde au travers de jeux d'apprentissage plus ou moins spécifiques. Comprendre comment et à quelles fins le professeur produit ses discours dans la classe représente l'enjeu majeur de ce travail. Le contexte de cette étude concerne deux classes de cycle II de l'école élémentaire, engagées dans une séance en Découverte Du Monde Vivant, relative au mode de vie du lombric (locomotion et besoins physiologiques). Cette recherche de nature fondamentale élabore une structure d'investigation capable de décrire de manière rigoureuse de quelle manière le savoir organise les transactions didactiques. Cette structure articule trois composantes qui sont les stratégies énonciatives didactiques, l'épistémologie pratique du professeur et les jeux d'apprentissage. L'élaboration et la mise en œuvre de ce modèle s'appuient sur l'étude de cas de deux professeurs, un débutant et un expérimenté. Ce modèle d'analyse, dans une logique comparatiste, emprunte à la fois au champ de la didactique et à celui de la linguistique. Il permet in fine, de saisir certaines des déterminations qui pèsent sur l'action conjointe en situation et de s'engager vers une première caractérisation des transactions didactiques.

La communication en milieu didactique est une spécification de la communication humaine. La théorie de l’action conjointe en didactique (TACD), développée par Sensevy, Mercier & al. (2005, 2007 et 2008), considère la production des discours du professeur et des élèves comme la manifestation de transactions didactiques dont le savoir est l’objet transactionnel. Ces transactions permettent à la fois la reconnaissance mutuelle des interlocuteurs et la participation à un jeu conjoint, qui consiste à construire et changer le monde au travers de jeux d’apprentissage plus ou moins spécifiques. Comprendre comment et à quelles fins le professeur produit ses discours dans la classe représente l’enjeu majeur de ce travail. Le contexte de cette étude concerne deux classes de cycle II de l’école élémentaire, engagées dans une séance en Découverte Du Monde Vivant, relative au mode de vie du lombric (locomotion et besoins physiologiques). Cette recherche de nature fondamentale élabore une structure d’investigation capable de décrire de manière rigoureuse de quelle manière le savoir organise les transactions didactiques. Cette structure articule trois composantes qui sont les stratégies énonciatives didactiques, l’épistémologie pratique du professeur et les jeux d’apprentissage. L’élaboration et la mise en oeuvre de ce modèle s’appuient sur l’étude de cas de deux professeurs, un débutant et un expérimenté. Ce modèle d’analyse, dans une logique comparatiste, emprunte à la fois au champ de la didactique et à celui de la linguistique. Il permet in fine, de saisir certaines des déterminations qui pèsent sur l’action conjointe en situation et de s’engager vers une première caractérisation des transactions didactiques
Didactic communication is a spécification of human communication. The Joint Action Theory in Didactic (JATD, Sensevy, Mercier &al. 2005, 2007 et 2008), considers the teacher’s and student’s discourse production as the didactics transactions demonstration. By this way, knowledge is seen as the transaction’s stake. These transactions allow at the same time the interlocutors’ mutual recognition and their participation to a joint game. This Game consists in building and changing the world, thanks to more or less specific learning games. This works’ major intention is to understand how and why the teacher produces his discourse in the class. This study’s context concerns two first graduate classes committed in a Discovery Living World lesson. This fundamental research works out an investigation framework able to describe how knowledge organizes didactics transactions. This framework joint three components : didactic enonciative strategies, teacher’s practical epistemology and learning games. The pattern’s development and implementation are based on the case study of two teachers : one beginner and one experienced. This analysis pattern uses at the same time didactic and linguistic approaches. It allows to grasp some of the determinations which influence the joint action of teacher and students and to turn a first characterization of the didactic transactions

The content of thought, which emerges from the processing of information from the social context lived, is a critical factor that guides whether the behavior is psychopathological or not. In cases where worry, anxiety and fear are dominant in the content of thought, the individual may find himself in some psychopathological processes. Adversity and uncertainty are the main factors that lead to the experience of worry, anxiety and fear which is the last point of these. Uncertainty of information from the social context lived, when matched with adversity, may lead to chaotic situations at the cognitive level, e.g., thought contents such as distortions in thought, severe anxiety and fear. Obsessive compulsive disorder derives from severe worry and anxiety. Although the disorder is classified under anxiety disorders, it is actually a thought distortion disorder. The individual finds himself repeating the strange behavior patterns accompanied by strange thought contents in order to get rid of the severe anxiety and accelerated thought cycle he is exposed to. Ambiguity and uncertainty also may lead to the accelerated thought cycle, ruminations, severe thought distortions, over-generalizations. Ruminations, especially, impair the individual’s ability to think and process emotions gradually. Obsessive Compulsive Disorder will be discussed in terms of ambiguity and uncertainty with the combination of adversity. Positive Psychotherapy, which is one of the latest effective technique in recovery processes of the diseases, will be mentioned.

In this paper, a detailed thermodynamic performance analysis of a transcritical condensing (TC) cycle is performed with pure CO2 and a blend of 48.5 % propane with 51.5 % CO2 as working fluids. A realistic thermodynamic model is used incorporating irreversibilities in turbo-machineries and heat exchangers. The Key finding is that the addition of propane elevates the heat rejection temperature, but does not impair any of the performance indicators. Such a fluid may be useful for power generation in concentrated solar power applications by using which a hike of up to 2 % can be realized in the thermal efficiency of a power plant.

Pipelines are one of the primary modes to transport hydrocarbon products throughout the world. A majority of these pipeline systems are buried, which are susceptible to ground movement that imposes axial forces and bending moments on the pipeline section. As a result of these forces and moments pipeline section may experience localized deformation that result in wrinkling, buckling and other damage mechanisms. This may impair the pipeline mechanical performance with respect to local stress concentration, lower strength and reduced fatigue life. Cyclic operational loads or ground movement events may result in strain reversals within the pipeline section that may lead to fracture through low cycle fatigue process. In this study, physical testing was conducted to examine the strength and fatigue life performance characteristics of hot rolled steel (44-W). The effects of the test sample bend radius, wall thickness and imposed displacement stroke range on fatigue performance were examined. The data was used to develop and refine continuum finite element modeling procedures that can be used to assess the influence of pipeline damage on fatigue life in a more detailed numerical simulation framework.

Automotive turbocharger radial inflow turbines are required to have both a high efficiency and a low inertia. In many cases this favours the use of a mixed-flow design. The inertia is minimised by scalloping the back-face, which removes a significant amount of material from the highest radius region of the hub. However, there is a concern that, for a mixed-flow geometry, the presence of a scallop introduces a forward-facing step to the inducer flow. This gives rise to the potential for an additional loss mechanism in the impeller. Two variants of a mixed-flow design, one having scallops and the other without, have been tested in a steady-state rig. The performance deltas are compared against the CFD representations. In reality there is the additional complexity of pulsing inlet conditions due to the operation of the exhaust valves of the piston engine. This causes severe variations in the inducer flow field. To assess whether the presence of a scallop might impair performance in an engine installation, a number of off-design CFD comparisons have been carried out using boundary conditions from a transient model covering a pulsing cycle.

Abstract The application of compressor water injection in aeroengines is of renewed interest in the civil aviation industry. Water due to its unprecedented heat capacity has the potential to cool the engine air through evaporation and thus reduce the NOx emissions formed in a combustion process. It is well known that the evaporative cooling increases thermodynamic cycle efficiency and thus improves the fuel economy. A relatively unexplored area, however, is the entropy generation due to water phase change as well as the balance between the corresponding entropy yield and the savings from the cooling of the core compressor flow. Hence, little consensus in the literature exists on the ultimate effect of water injection on compressor efficiency. In this study, a numerical analysis of water injection on an axial transonic rotor was carried out. The compressor model was tested at near-peak efficiency conditions with and without water injection. The flow was analysed using the Eulerian-Lagrangian approach with two-way coupling and the k-ω Shear Stress Transport turbulence model with Reattachment Modification. A universal, second thermodynamic law approach to quantify the entropy generation is proposed and used to evaluate the compressor flow. Results show that evaporation can facilitate the compression process and does not impair the compressor efficiency if applied at favourable conditions. The entropy generation in droplet-laden flow scales according to the gains from cooling effect and losses due to the evaporation and increased friction in the fluid. Some of the discrepancies in the public domain could be addressed, showing that the observed improvement in compressor efficiency is highly sensitive to the entropy flux measurement location. Most benefits from water injection were observed at the rotor tip proving the case for part-span injection from an entropy balance perspective.

Using solid particulates as a heat absorption and transfer medium in solar concentrated systems is a solution for collecting and storing thermal energy. Solid particulates, such as sand, are relatively inexpensive and are much less corrosive and expensive to maintain than molten salts. Small particles may be stored easily, and can be used as a heat transfer medium for use with a suitable heat exchanger. Despite their anticipated low cost, excessive degradation of the particulates requiring replenishment or disrupting operation could impair the overall economics. Consequently, the durability of the particulates should be verified. Responding to this need, this study examines the durability of solid particulates as a heat transfer medium in a closed cycle for concentrated solar power central receiver systems. Specifically, this study analyzes the combination of attrition and sintering of sand with varying temperatures. Attrition is the reduction of a particle’s mass and sintering is a process of fusing two or more particles together to form a larger agglomerate. In a closed cycle, particularly for a concentrated solar power tower, a particle will experience typical temperatures from 600°C to 1000°C. The increase in temperature may change the physical characteristics of the particles and along with any impurities may promote lower softening point bonding. Thus, it is important to investigate particle durability at high temperatures. The experimental procedure used in this investigation involves heating and abrading particulates of a known mass and size distribution to temperatures between 600°C and 1000°C, and also at 25°C to observe attrition only. The testing is conducted using a specially designed experimental apparatus described below. The heated particulates are contained in a metal cylinder. Inside the cylinder is another cylinder made of a porous silicon carbide foam. As the temperature is held constant, the particulate sample is rotated 180 degrees around a horizontal axis every 15 seconds from a low position to a higher position so that the particulates fall and abrade against each other. This process is repeated for a known number of cycles (many thousands). Then the resulting particulate size distribution is measured to determine the amount of attrition and sintering occurred during the experiment. The particulates tested are various types of sand with varying mean diameters and composition, along with a ceramic particulate similar to hydraulic fracturing proppants. Sample composition, sample size distribution, and temperature will be used to establish parameters for rates of attrition and sintering. These rates will be used to predict the behavior of particulates in a concentrated solar power tower closed cycle.

Abstract Practice and experiments with squeeze film dampers (SFDs) sealed with piston rings (PRs) show the lubricant exits through the PR slit, i.e. the gap made by the PR abutted ends when installed, forced as a jet during the portion of a rotor whirl cycle generating a positive squeeze film pressure. In the other portion of a whirl cycle, a sub ambient dynamic pressure ingests air into the film that mixes with the lubricant to produce a bubbly mixture. To reduce persistent air ingestion, commercial air breathing engines utilizing PRSFDs demand of a sufficiently large lubricant supply pressure (Ps), and hence a larger flow rate that is proportional to the journal squeeze velocity (vs = amplitude r × frequency of motion ω). The stringent requirement clearly limits the applicability and usefulness of SFDs. This paper presents a computational physics model for a sealed ends SFD operating with a mixture and delivers predictions benchmarked against profuse laboratory test data. The model implements a Reynolds equation adapted for a homogeneous bubbly mixture, includes temporal fluid inertia effects, and uses physics based inlet and outlet lubricant conditions through feed holes and PR slit, respectively. In the experiments for model validation, a SFD damper, 127 mm in diameter D, film land length L = 25.4 mm (L/D = 0.2), and radial clearance c = 0.371 mm, is supplied with an air in ISO VG2 oil bubbly mixture of known GVF, zero (pure oil) to 50% in steps of 10%. The mixture supply pressure varies from Ps = 2.06 bar-g (30 psig) to 6.20 bar-g (90 psig). Located in grooves at the top and bottom of the journal, a piston ring (PR) and an O-ring (OR) seal the film land. The OR does not allow any oil leakage or air ingestion; hence the supplied mixture discharges thru the PR slit into a vessel submerged within a large volume of lubricant. Dynamic load tests with a single frequency ω, varying from 10 Hz to 60 Hz, produce circular centered orbits with amplitude r = 0.2c. The measurements record the exerted forces and journal motions and an analysis delivers force coefficients, damping and inertia, representative of the exerted frequency range. The model predicts the pressure field and evolution of the gas volume fraction (GVF) within the film land and, in a simulated process replicating the experimental procedure, delivers representative force coefficients. For all Ps conditions, both predictions and tests show the SFD added mass coefficients significantly decrease as the inlet GVF (βs) increases. The experimentally derived damping coefficients do not show a significant change, except for tests with the largest concentration of air (βs = 0.5). The predicted damping differs by 10% with the test derived coefficient which does not readily decrease as the inlet GVF (βs) increases. The added mass coefficients, test and predicted, decrease with βs, both being impervious to the magnitude of supply pressure. The test PRSFD shows a quadrature stiffness due to the sliding friction between the PR being pushed against the journal. An increase in supply pressure exacerbates this unique stiffness that may impair the action of the squeeze film to dissipate mechanical energy. The comprehensive test results, first of their kind, demonstrate that accurate modeling of SFDs operating with air ingestion remains difficult as the flow process and the paths of its major components (air and liquid) are rather complex.