542 research outputs found
Data for Repository - Tattersall Roussel Voituron Teulier
No full textData used to construct figures 1, 2, and
Equilibrium transition study for a hybrid MAV
No full textWind tunnel testing was performed on a VTOL aircraft in order to characterize longitudinal flight behavior during an equilibrium transition between vertical and horizontal flight modes. Trim values for airspeed, pitch, motor speed and elevator position were determined. Data was collected by independently varying the trim parameters, and stability and control derivatives were identified as functions of the trim pitch angle. A linear fractional representation model was then proposed, along with several methods to improve longitudinal control of the aircraft
Mitochondrion at the centre of "metabolism - body mass - longevity" triptych
No full textLes mécanismes sous-jacents aux traits d’histoire de vie sont complexes et ne sont pas totalement compris à ce jour. De par leur capacité à générer de l’énergie cellulaire (ATP), des espèces réactives de l’oxygène (ROS) et de la chaleur, les mitochondries impactent les performances individuelles (taille, croissance et survie) et les traits d’histoire de vie des eucaryotes. La masse corporelle influence les processus et les structures biologiques, quelle que soit l’échelle biologique appréhendée. Cette thèse propose ainsi, par une approche écophysiologique, de comprendre le lien entre la bioénergétique mitochondriale et la masse corporelle, afin d’apporter une base physiologique aux traits d’histoire de vie des mammifères. Les résultats obtenus mettent en avant l’existence d’un patron allométrique général chez les mammifères. La consommation d’oxygène (O), la production radicalaire et la synthèse d’ATP mitochondriales, sont toutes corrélées négativement avec la masse corporelle ; alors que les rapports entre ces différents processus (ATP/O, ROS/O et ROS/ATP) sont indépendants de la masse corporelle. Malgré un couplage oxydation-phosphorylation (ATP/O) identique entre les espèces, les mammifères de grande taille sont plus efficaces, en produisant plus d’ATP par oxygène consommé, comparés aux petites espèces. Cette meilleure capacité est expliquée par des membranes mitochondriales moins perméables aux protons et permet aux mammifères de grande masse corporelle d’allouer plus d’énergie à leurs performances individuelles. Les données mettent aussi en évidence que les contraintes physiologiques, exigées par une très petite masse corporelle, peuvent entrainer des discordances d’une échelle biologique à une autre. Au niveau cellulaire seulement, Mus mattheyi (≈ 5 g) présente un profil bioénergétique similaire à celui d’une souris quatre fois plus lourde (Mus musculus, ≈ 20 g). Contrairement aux attendus allométriques, M. mattheyi présente des taux métaboliques faibles et une efficacité mitochondriale (ATP/O) élevée, lui permettant de produire plus d’ATP par oxygène consommé qu’une espèce de même masse corporelle. Enfin, cette thèse démontre que la dépendance de la production de ROS à l’activité mitochondriale est identique entre les espèces. En effet, une réduction de l’activité mitochondriale maximale, au-delà de 70-75%, entraine une production accrue de ROS dans la mitochondrie, quelle que soit l’espèce étudiée. L’invariance de cette valeur seuil et des stoechiométries entre processus bioénergétiques (ATP/O, ROS/O et ROS/ATP), montre une forte conservation de ces paramètres mitochondriaux au cours de l’évolutionNowadays, the mechanisms underlying life history traits are complexed and not fully understood. Through their ability to generate cellular energy (ATP), reactive oxygen species (ROS) and heat, mitochondria impact individual performances (size, growth and survival) and life history traits of organisms. Body mass influences a lot of biological processes and structures at all biological scales. Thus, this thesis proposes, through an eco-physiological approach, to understand the link between mitochondrial bioenergetics and body mass, in order to provide a physiological basis for mammalian life history traits. The results obtained highlight the existence of a general allometric pattern in mammals. Mitochondrial oxygen consumption (O), ROS production and ATP synthesis, correlate negatively with body mass; whereas ratios between these different processes (ATP/O, ROS/O and ROS/ATP) are independent of body mass. Despite identical oxidation-phosphorylation coupling (ATP/O) between species, large mammals are more efficient, producing more ATP per oxygen consumed, compared to smaller ones. This capacity allows large mammals to allocate more energy to their individual performances and is explained by mitochondrial membranes that are less permeable to protons. The data also show that physiological constraints imposed by a very small body mass can lead to inconsistencies from one biological scale to another. Only at the cellular level, Mus mattheyi (≈ 5 g) presents a bioenergetics profile similar to that of a mouse four times heavier (Mus musculus, ≈ 20 g). Contrary to allometric expectations, M. mattheyi has low metabolic rates and high mitochondrial efficiency (ATP/O), allowing it to produce more ATP per oxygen consumed than a species of the same body mass. Finally, this thesis demonstrates that the dependence of ROS production on mitochondrial activity is similar between species. A reduction in maximum mitochondrial activity, beyond 70-75%, leads to a drastic increased of mitochondrial ROS production. The invariance of this threshold value and of the stoichiometry between bioenergetics processes (ATP/O, ROS/O and ROS/ATP), suggests a strong conservation of these mitochondrial parameters during evolutio
Sémantique de l'Espace et du déplacement
No full text@incollection{OL-MATHET-2005, author = {Yann Mathet}, title = {{S{é}mantique de l'Espace et du d{é}placement}}, chapter = {6}, pages = {215-265}, booktitle = {S{é}mantique et traitement automatique des langues}, editor = {Patrice Enjalbert}, series = {Trait{é} IC2, s{é}rie Cognition et traitement de l'information}, publisher = {Herm{è}s Sciences, Lavoisier}, year = {2005}
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No full textLe concept de compromis évolutif est central dans la compréhension de l'évolution des histoires de vie ; cependant, les mécanismes sous-jacents sont encore peu compris. Généralement, les études physiologiques sur les compromis d'histoire de vie ont porté sur les phénomènes d'allocation des ressources. Depuis une dizaine d'année, plusieurs études sur les causes fonctionnelles des compromis d'histoire de vie ont permis de mettre en évidence un lien entre le stress oxydatif et les différentes composantes des performances de l'organisme. Nous proposons que le fonctionnement mitochondrial, source principale de production d'énergie (adénosine triphosphate, ATP) et d'espèces réactives de l'oxygène (reactive oxygenspecies, ROS) puisse être le lien entre les processus d'allocation des ressources et de stress oxydatif. Par des approches descriptives et expérimentales, nous avons étudié les relations entre les flux d'énergie, le stress oxydatif et la croissance sur un modèle amphibien anoure, la grenouille rousse Rana temporaria. L'intérêt principal de ces travaux de thèse a été de considérer la balance oxydative dans son ensemble (pro-oxydants, anti-oxydants et dégâts oxydatifs) ainsi que le flux d'énergie pondéré par l'efficacité de la mitochondrie à convertir l'énergie (le rapport ATP/O). Des têtards, exposés de façon chronique à un découplant (2,4- dinitrophénol) au cours de leur développement, présentent un ralentissement de croissance, ainsi qu'une diminution de l'efficacité de conversion énergétique mitochondriale et un meilleur statut oxydatif (moins de ROS produits et peu de dégâts oxydatifs malgré la diminution des capacités anti-oxydantes). Par ailleurs, les paramètres physiologiques décrits chez des grenouilles sauvages présentant des différences de taille corporelles montrent une efficacité de conversion énergétique mitochondriale plus élevée chez les grenouilles à croissance élevée. De plus, les résultats sur la balance oxydative des grenouilles adultes montrent que la compréhension des relations entre paramètres de la balance oxydative implique de replacer les variables dans leur rôle physiologique. L'ensemble de ces résultats suggèrent que (i) l'étude d'un seul paramètre de la balance oxydative ne permet ni d'émettre des conclusions sur les autres paramètres, ni de comprendre l'impact de la balance oxydative sur les organismes ; (ii) l'efficacité de conversion énergétique mitochondriale est un facteur affectant les flux d'énergie et pourrait contrôler la quantité d'énergie disponible pour la croissance de l'animal. Cette thèse montre la nécessité d'étudier les mécanismes sous-jacents aux compromis évolutifs en fusionnant les notions d'allocation des ressources et de balance oxydative, et ouvre de nombreuses voies vers des études plus intégrativesThe concept of trade-off is central to our understanding of life history evolution but the underlying mechanisms are still poorly understand. Traditional physiological studies of life history trade-offs focused mainly on the differential allocation of limited resources. During the last decade, numerous studies on functional causes of life history trade-off have shown that oxidative stress was related to different components of animal performances. Here, we propose that the functioning of mitochondria, which is the main site of both energy (adenosine triphosphate, ATP) production and of reactive oxygen species (ROS) generation, could be the link between the resource allocation and oxidative stress processes. From descriptive and experimental approaches, we investigate the relationship between energy flow, oxidative stress and growth in a amphibian anuran model, the common frog Rana temporaria. All studies presented in this thesis aim to consider the overall oxidative balance (pro-oxidants, anti-oxidants and oxidative damages) and the energy flow accounting for mitochondrial efficiency of the energy transduction system (the ATP/O ratio variation) to better understand growth patterns in a ectotherm that influence both survival and reproductive capacities. Chronic exposure to an uncoupler (2,4-dinitrophenol) during tadpole development induced a lower growth rate associated with a decreased mitochondria efficiency of energy transduction and an improved oxidative status (lower ROS production and low oxidative damage despite low antioxidant defenses). In addition, the description of physiological parameters of wild frogs exhibiting dissimilar body size shows a higher energy efficiency transduction in frogs exhibiting high growth rate. Thus, the results on the oxidative balance of frogs show that understanding the relationship between the variables of the oxidative balance involves replacing their physiological role. Altogether, our results suggest that (i) the study of a single oxidative balance setting alone does not allow to conclude on other parameters and on the impact of oxidative stress on the organism; (ii) understanding the mitochondrial efficiency of energy transduction is a factor affecting the flow of energy and could drive the amount of energy available for the animal growth. This thesis demonstrates the need to study the underlying mechanisms of trade-offs in merging the resource allocation and oxidative balance approaches, and open the way for more integrative studie
"I' ll tell you a story that will make you believe" in narratives: the role of metafiction in the novel and in the film Life of Pi
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Inglês: Estudos Linguísticos e Literários, Florianópolis, 2015.Recentes estudos propõem que adaptações cinematográficas sejam entendidas como fonte de criação, os quais refletem contextos e interpretações diferentes do texto em que são baseadas. Nessa dissertação, propõe-se uma análise comparativa do romance Life of Pi (2001), de Yann Martel e do filme homônimo dirigido por Ang Lee (2012). A análise tem como objetivo identificar a presença e o modo em que a metaficção é construída no romance e no filme, e quais são alguns significados produzidos por ela em ambos os textos, tanto o literário quanto o fílmico. A concepção de metafição se baseia nas definições de Linda Hutcheon e Patricia Waugh. Por metaficção, entende-se a ficção consciente de si, que expõe o processo de escrita ao leitor e o convida a ter um papel ativo na construção do significado. Após uma análise comparativa dos dois textos, conclui-se que a metaficção está presente em ambos, tanto tematicamente como estruturalmente. As reflexões sobre narrativas apresentadas pelos personagens, o uso de vários níveis narrativos e de intertextualidade revelam diferentes usos da metafição em ambos. A diferença mais importante entre o romance e o filme Life of Pi está no uso dos níveis narrativos. Enquanto o romance possui um ?autor? sem nome que apresenta a história aos leitores, o filme possui um diretor implícito que deixa pistas de qual versão da história de Pi é ?real? no contexto da narrativa. Essa diferença dá ao romance um final aberto, em que o leitor deve escolher qual versão da história ele acredita, enquanto o filme possui uma resolução para essa questão. O filme, então, pode ser entendido como um testemunho, uma narrativa de trauma de um sobrevivente de um naufrágio e da experiência de migração, enquanto o livro não apresenta uma decisão em relação às versões da história, deixando o leitor aberto a qualquer possibilidade.Abstract : Recent studies propose that Film Adaptations should be understood as sources of creation, which also reflect a different context and interpretation from the text upon which they were based. In this thesis, I propose a comparative analysis of the novel Life of Pi (2001), by Yann Martel, and the homonymous film directed by Ang Lee (2012). The analysis has the objective of identifying the presence and the way in which metafiction is constructed in the novel and in the film, and what are some of the meanings produced by it in both texts, the filmic and the literary. The concept of metafiction was based on the definitions by Linda Hutcheon and Patricia Waugh. It is understood as the self-conscious fictional text, which exposes the writing process to the readers and invites them to have an active role in the construction of meaning. In the comparative analyses of the two texts, I have proved that metafiction is present in the two texts, both thematically and structurally. The reflections of the characters on narrative itself as well as the use of different narrative levels and intertextual references reveal different uses of metanarrative in both film and novel. The most important difference between the novel and the film Life of Pi is in their uses of different narrative levels. While the novel has an unnamed =author? who presents the story to the readers, the film has an implicit director who leaves =clues? of which version of Pi?s story is ?real? in the context of the narrative. This difference gives to the novel an open end, facein which the readers must choose which version of the story they believe in, while the film presents a resolution to this question. The film, thus, can be understood as a testimony narrative, a narrative of the trauma of a survivor from a shipwreck and from the experience of migration, while the novel does not decide for one of the versions of the story, enabling a more inconclusive reading
Signal honesty and condition-dependance in a multimodalsexual signaling system
No full textDans un contexxte de sélection sexuelle, les signaux émis par les mâles sont censés refléter honnêtement leur condition. Etant donné que la condition est un concept multifactoriel, il a été propposé que les différentes composantes des signaux sexuels reflètent différents aspects de la condition de l'émetteur (Hypothèse des messages multiples). Ma thèse a pour but de tester la condition-dépendance des signaux sexuel et l'hypothèse des messages multiples en manipulant différents aspects de la condition mâle ; et d'étudier les moyens de contourner un système de signalement honnête par des tactiques de reproduction alternatives. Nous avons conduit ces expériences chez Hyla arborea, espèce chez laquelle les mâles émettent des signaux comprenant des composantes accoustiques et visuelles impliquées dans le choix du partenaires sexuel. Nos résultats suggèrent que le taux de chant intra-bout, une propriétédynamique, est un indicateur de la condition actuelle, alors que la fréquence dominante, une prpriété statique du chant, semble indépendante de la condition actuelle mais liée à la condition passée. Les composantes visuelles du signal sont indépendantes des variations du statut mutirtionnel à court terme mais pourraient être des indicateurs de la condition passée. L'adoption d'une tactique satellite dépend plus de la condition passée que de l'actuelle. Plusieurs composantes du signal sont liées à différents aspects de la condition du mâle, ce qui supporte l'hypothèsedes messages multiples. CEpendant, les relations entre les composantes et les aspects de la condtion sont faibles et nous poussent à considérer également la dynamique évolutive des systèmes de signalements.In a sexual selection context, signals displayed by males are supposed to reflect honestly their condition. Given that condition is a mutlifactorial concet, it has been propposed that the multiple compopnenets often involved in sexual signal reflects differents aspect of emitter's condition (multiple messages hypothesis). My thesis aimed at testing the condition-dependance of sexual signals and the muliple messages hypothesis by manipulating different aspects of male condition ; and at investigating ways to circumvent an honest signalling systems through alternative reproductive tactics. We conduced these experiments on the European treefrog (Hyla arborea), a species in wich males display signals with both accoustic ansd visual components used by females during mate choice. Our results suggest that the within-bout call rate, a dynamic call property, is a reliable indicator of current condition while call dominant frequency, a static call property, seems to be independant from current conditions but is linked to past condition. Visual signal components are independant from variations in nutritional status on short term but are linked to male condition in the field and may be indicators of past condition. The adoption of satellite tactic depends more on past condition than on current condition.. As several signal components are related to the emitter'scondition and seem to be independant upon distinct aspects of this condition, our results mainly support the multiple messages hypothesis. However, the weak correlations betxeen signal components and condition aspects found in this study highlight the necessity to consider also the evolutionary dynamics of signalliings systems
Endothermy and body mass : effect on mitochondrial bioenergetics
No full textLes oiseaux et les mammifères sont des endothermes qui, à travers des mécanismes de thermorégulation, maintiennent une température corporelle élevée et relativement constante (36°- 41°C). Seulement, les oiseaux ont la singularité de présenter un taux métabolique, une température corporelle ainsi qu’une longévité supérieure à celle des mammifères de même masse. Les oiseaux semblent alors défier une variété de théories écologiques, laissant penser que les différences établies entre ces deux clades, au niveau du métabolisme et des processus de vieillissement, pourraient être la conséquence d’un fonctionnement mitochondrial distinct. Ma thèse avait pour objectif d’étudier l'efficacité du fonctionnement mitochondrial chez les oiseaux et à le comparer à celui des mammifères, récemment exploré. Il était également question de comprendre comment la masse corporelle et la température corporelle (deux grands déterminants des propriétés biologiques des organismes), affectent le métabolisme énergétique mitochondrial, les performances, le vieillissement et la thermorégulation des endothermes. J’ai ainsi étudié l’effet de la masse corporelle sur la bioénergétique mitochondriale des oiseaux (consommation d’oxygène, synthèse d’ATP, production de ROS et efficacité du couplage mitochondriale), à partir de différents tissus tels que le muscle squelettique, le cœur, le foie et le sang. Des analyses comparatives phylogénétiques ont été utilisées pour étudier les patterns allométriques aviaires. J'ai également effectué un "zoom" sur les patterns allométriques en comparant des mitochondries isolées du muscle squelettique de pigeons et de rats, de masse corporelle similaire, à différentes températures in vitro et en utilisant différents substrats mitochondriaux, afin de comparer et de décortiquer plus en détail le fonctionnement mitochondrial respectif des oiseaux et des mammifères. Les différents travaux réalisés montrent globalement que l’effet de la masse corporelle sur la bioénergétique mitochondriale des oiseaux est 1) dépendante des tissus considérés, 2) dépendante du niveau d’activation du métabolisme et 3) évolue selon un pattern similaire aux mammifères. Cette thèse montre également l’intérêt de prendre en compte les différences de régulation de la température corporelle en sein des endothermes mais également les préférences d’utilisation des substrats mitochondriaux dans les études comparatives oiseaux/mammifères.Birds and mammals are endotherms which, through thermoregulatory mechanisms, maintain a high and relatively constant body temperature (36°- 41°C). However, birds are remarkable in that their metabolic rate, body temperature, and longevity are higher than those of mammals of the same mass. Birds therefore seem to challenge various ecological theories, suggesting that the differences observed between these two clades, in terms of metabolism and ageing processes, could be the consequence of a distinct mitochondrial function. The aim of my thesis was to study the efficiency of mitochondrial function in birds and compare it with that of mammals, which has recently been explored. The aim was also to understand how body mass and body temperature (two major determinants of the biological properties of organisms) affect mitochondrial energy metabolism, performance, ageing, and thermoregulation in endotherms. I studied the effect of body mass on mitochondrial bioenergetics in birds (oxygen consumption, ATP synthesis, ROS production, and mitochondrial coupling efficiency), using different tissues such as skeletal muscle, heart, liver, and blood. Comparative phylogenetic analyses were used to study avian allometric patterns. I also 'zoomed in' on allometric patterns by comparing mitochondria isolated from the skeletal muscle of pigeons and rats, of similar body mass, at different in vitro temperatures and using different mitochondrial substrates, to compare and dissect in more detail the respective mitochondrial function of birds and mammals. Overall, the various studies carried out show that the effect of body mass on mitochondrial bioenergetics in birds is 1) tissue-dependent, 2) dependent on the level of metabolic activation, and 3) follows a pattern like that of mammals. This thesis also shows the importance of considering differences in body temperature regulation within endotherms, as well as preferences in the use of mitochondrial substrates in comparative studies between birds and mammals
The Political Economy of Textbook Writing: Paul Samuelson and the making of the first ten Editions of Economics (1945-1976)
No full textOver the past two decades, numerous contributions to the history of economics have tried to assess Paul Samuelson’s political positioning by tracing it in the subsequent editions of his famous textbook Economics. This literature, however, has provided no consensus about the location of Samuelson’s political ideas. While some authors believe that Samuelson has always had inclinations toward interventionism, others conclude that he more often acted as a pro-business advocate. The purpose of this paper is not to argue for one of these two interpretations but to depict the making of Economics itself as a political process. By ‘political’ it is not meant the conduct of party politics but the many political elements that a textbook author has to take into account if he wants to be published and favorably received. I argue that the “middle of the road” stance that Samuelson adopted in the book was consciously constructed by the MIT economist, with the help of his home institution and his publishing company, McGraw-Hill, to ensure both academic freedom and the success of the book. The reason for which the stance developed is related to pre-McCarthyist right-wing criticisms of the textbook and how Samuelson and the MIT department had to endure the pressures from members of the Corporation (MIT’s Board of Trustees), who tried to prevent the publication of the textbook and threatened Samuelson’s tenure at MIT as soon as 1947 – when early manuscripts were circulated. As a result, it was decided in accordance with both the Corporation and McGraw-Hill that the Readings volume would be published to balance conflicting ideas about state intervention. Following these early criticisms, the making of the subsequent editions relied on a network of instructors and referees all over the US in order to make it as successful and consensual as possible. This seemed to work quite well in the 1950s and for a good portion of the 1960s, until Economics became victim of its own success and was seen, in an ironical twist of fate, as a right wing text by younger, radical economists. From now on, Samuelson will try to have his book sent as often as possible to the radicals for referring process, with mixed results. Eventually, the book became criticized from both its left and its right.Paul Samuelson, Economics, Textbook, Politics, Economic Education
Believing in Tigers: Anthropomorphism and Incredulity in Yann Martel’s Life of Pi
No full textRather than the Bengal tiger with whom he shares a lifeboat for 227 days, Pi Patel's true adversary in Yann Martel's Life of Pi is doubt. Pi and his author-narrator align their conception of God with an idea of the work required to believe in narratives that surpass the limits of possibility. Neither Pi nor his author-narrator makes any distinction between the temporary suspension of disbelief and firm religious faith, between the acceptance of a believable story and the embrasure of an omnicient God. By dramatizating the anthropomorphic impulse, which finds expression primarily in response to doubt or disbelief, Life of Pi succeeds in conflating poetic and religious faith
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