Au large de L’Île-d’Yeu – Trupailles

La prospection sur le site des Trupailles avait pour but la recherche d’une épave du xviiie s. En raison du mauvais temps pendant la période retenue, du 20 au 27 juin 1992, nous avons travaillé sur deux zones. Les Trupailles (sud-ouest de l’île) : le mauvais temps en cet endroit, les règles particulières liées à cette zone rendent la prospection future très difficile. Au cas où un site serait repéré, les conditions de travail seraient très exigeantes en sécurité. Le Petit Champ (nord-ouest de..

Diversity in the organization of elastin bundles and intramembranous muscles in bat wings

Unlike birds and insects, bats fly with wings composed of thin skin that envelops the bones of the forelimb and spans the area between the limbs, digits, and sometimes the tail. This skin is complex and unusual; it is thinner than typical mammalian skin and contains organized bundles of elastin and embedded skeletal muscles. These elements are likely responsible for controlling the shape of the wing during flight and contributing to the aerodynamic capabilities of bats. We examined the arrangement of two macroscopic architectural elements in bat wings, elastin bundles and wing membrane muscles, to assess the diversity in bat wing skin morphology. We characterized the plagiopatagium and dactylopatagium of 130 species from 17 families of bats using cross‐polarized light imaging. This method revealed structures with distinctive relative birefringence, heterogeneity of birefringence, variation in size, and degree of branching. We used previously published anatomical studies and tissue histology to identify birefringent structures, and we analyzed their architecture across taxa. Elastin bundles, muscles, neurovasculature, and collagenous fibers are present in all species. Elastin bundles are oriented in a predominantly spanwise or proximodistal direction, and there are five characteristic muscle arrays that occur within the plagiopatagium, far more muscle than typically recognized. These results inform recent functional studies of wing membrane architecture, support the functional hypothesis that elastin bundles aid wing folding and unfolding, and further suggest that all bats may use these architectural elements for flight. All species also possess numerous muscles within the wing membrane, but the architecture of muscle arrays within the plagiopatagium varies among families. To facilitate present and future discussion of these muscle arrays, we refine wing membrane muscle nomenclature in a manner that reflects this morphological diversity. The architecture of the constituents of the skin of the wing likely plays a key role in shaping wings during flight

Characterization of juvenile pyroclasts from the Kos Plateau Tuff (Aegean Arc): insights into the eruptive dynamics of a large rhyolitic eruption

Silicic pumices formed during explosive volcanic eruptions are faithful recorders of the state of the magma in the conduit, close to or at the fragmentation level. We have characterized four types of pumices from the non-welded rhyolitic Kos Plateau Tuff, which erupted 161,000years ago in the East Aegean Arc, Greece. The dominant type of pumice (>90vol.%) shows highly elongated tubular vesicles. These tube pumices occur throughout the eruption. Less common pumice types include: (1) "frothy” pumice (highly porous with large, sub-rounded vesicles), which form 5-10vol.% of the coarsest pyroclastic flow deposits, (2) dominantly "microvesicular” and systematically crystal-poor pumices, which are found in early erupted, fine-grained pyroclastic flow units, and are characterized by many small (<50μm in diameter) vesicles and few mm-sized, irregular voids, (3) grey or banded pumices, indicating the interaction between the rhyolite and a more mafic magma, which are found throughout the eruption sequence and display highly irregular bubble shapes. Except for the grey-banded pumices, all three other types are compositionally identical and were generated synchronously as they are found in the same pyroclastic units. They, therefore, record different conditions in the volcanic conduit leading to variable bubble nucleation, growth and coalescence. A total of 74 pumice samples have been characterized using thin section observation, SEM imagery, porosimetry, and permeametry. We show that the four pumice types have distinct total and connected porosity, tortuosity and permeability. Grey-banded pumices show large variations in petrophysical characteristics as a response to mingling of two different magmas. The microvesicular, crystal-poor, pumices have a bimodal bubble size distribution, interpreted as reflecting an early heterogeneous bubble nucleation event followed by homogeneous bubble nucleation close to fragmentation. Finally, the significant differences in porosity, tortuosity and permeability in compositionally identical tube and frothy pumices are the result of variable shear rates in different parts of the conduit. Differential shear rates may be the result of either: (1) pure shear, inducing a vertical progression from frothy to tube and implying a relatively thick fragmentation zone to produce both types of pumices at the same time or (2) localized simple shear, inducing strongly tubular vesicles along the wall and near-spherical bubbles in the centre of the conduit and not necessarily requiring a thick fragmentation zon

Outils pour l'enseignement du français aux Asiatiques rapport de recherche PAREA 1987-88 /

Titre de la couv.Également disponible en version papierTitre de l'écran-titre (visionné le 9 déc. 2009)Bibliogr

Projet mathétactiques élaboration d'un modèle d'enseignement des mathématiques liant constructivisme et résolution de problèmes /

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Fantasme d'immersion dans les poétiques de construction de mondes : complétude et canonicité, de Tolkien aux univers partagés

En prenant comme point de départ l'interprétation de l'épopée homérique par Erich Auerbach, ce mémoire se consacre à la notion d'immersion fictionnelle, non sous son versant psychologique de phénomène contingent de la conscience imageante, mais sous son versant imaginaire, en tant que mythe sociétal d'immédiateté déterminant des stratégies esthétiques et médiatiques concrètes, que j'articule autour des poétiques contemporaines de construction de mondes (world building). L'enjeu est de saisir les répercussions esthétiques de ce fantasme d'une représentation qui occulterait à la fois sa médiateté et le réel-sensible, à une époque où la transfictionnalité et la transmédiaticité s'élèvent tranquillement comme modes narratifs dominants de notre culture occidentale contemporaine. Avec cette conviction que le terme d'immersion doit être replacé dans le cadre de ses effets, le premier chapitre s'affairera à démêler quelques difficultés théoriques que pose la notion en la problématisant sous l'égide des questions ontologiques de vérité et de la position phénoménologique de Sartre sur l'imaginaire. Tout en posant les outils théoriques nécessaires aux analyses subséquentes, le deuxième chapitre approfondit cette problématisation en empruntant aux théories modales des mondes possibles un cadre conceptuel opératoire, qui amènera, notamment grâce au concept formalisé de «~monde~», à concevoir la fiction comme un mouvement de distanciation. Appuyé par la lecture du roman tolkienien, le troisième chapitre tourne le fantasme d'immersion du côté d'une pulsion encyclopédique de complétude, concrétisée par des stratégies textuelles d'accumulation informationnelle et de virtualisation de données diégétiques laissées en suspens -- effets d'actualité que je qualifie d'extra-narratifs en les présentant en contraste des principes prescriptifs du \emph{muthos} aristotélicien formant une chaîne causale téléologique fondée sur une loi d'économie narrative. Le quatrième et dernier chapitre, articulé autour de la notion encore trop peu étudiée de canonicité, observe les poétiques de construction de mondes telles qu'elles se désamorcent elles-mêmes, dans le contexte des univers partagés, en engendrant des incohérences logiques donnant lieu à la tenue d'un discours auctorial-éditorial régissant les vérités fictionnelles comme moyen de maintenir l'immersivité de la représentation. L'analyse générique des comic-books de superhéros et une enquête sur la gestion éditoriale de l'univers de Star Wars permettront d'identifier les multiples modalités de délimitation de la frontière entre canon et apocryphe. En conclusion, je reviens brièvement sur la notion d'immersion, ainsi exemplifiée, en la resémiotisant comme une médiation compétitive de mise en présence de l'être.Starting from Erich Auerbach's interpretation of the Homeric epic, this master's dissertation studies the notion of fictional immersion, not in its psychological aspect of a contingent phenomena of human consciousness, but rather in its collective imaginary sense, as a societal myth of immediacy generating concrete aesthetic and media strategies that I investigate from the standpoint of contemporary poetics of world building. The objective is to apprehend the aesthetic repercussions of this desire for a mediation that would conceal both the real and its own mediacy, in a time where transfictionality and transmedia storytelling are becoming more and more the dominant narrative modes of our contemporary western culture. Under the conviction that immersion must be looked at as a set of cultural strategies, the first chapter unravels some theorical difficulties bounded to the term by problematizing it towards ontological questions of truth and Sartre's phenomenological stance on the imaginary. While laying a necessary theorical toolset for subsequent analyses, the second chapter examines these problems by borrowing to possible worlds modal theories a set of working concepts, which will lead to the assumption that fiction is a movement of distanciation, notably with the aide of the formal concept of ``world''. Through a reading of the tolkienian novel, the third chapter directs the desire for immersion towards an encyclopedic impulsion for completeness, embodied by textual strategies such as informational proliferation and allusion to virtual diegetic data -- strategies leaving an impression of the actual that I describe as extra-narrative in contrast to Aristote's \emph{muthos} forming a teological causal chain based on a principle of an unitary narrative. The fourth and final chapter, articulated around the still too little studied notion of canonicity, observes poetics of world building as they neutralize themselves, particularly with shared universes, by generating logical inconsistencies giving birth to authorial and editorial discourses stating fictional truths as a way of maintaining the mediation's immersivity. The analysis of the superhero comics genre and an inquiry of the editorial management of the Star Wars universe will exemplify the multiple modalities of this delimitation between the canon and the apocryphal. As a conclusion, I briefly come back to the notion of immersion itself by redescribing it as a competitive mediation of presence

Portrait actualisé des croyances et des pratiques en évaluation des apprentissages au collégial rapport

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Petrological Insights into Shifts in Eruptive Styles at Volcán Llaima (Chile)

Tephra and lava pairs from two summit eruptions (ad 2008 and 1957) and a flank fissure eruption (∼ ad 1850) are compared in terms of textures, phenocryst contents, and mineral zoning patterns to shed light on processes responsible for the shifts in eruption style during typical eruptive episodes at Volcán Llaima (Andean Southern Volcanic Zone, Chile). The mineralogy and whole-rock compositions of tephra and lavas are similar within eruptive episodes, suggesting a common magma reservoir for Strombolian paroxysms and lava effusion. The zoning profiles and textures of plagioclase record successive and discrete intrusions of volatile-rich mafic magma accompanied by mixing of these recharge magmas with the resident basaltic-andesitic crystal mushes that are commonly present at shallow levels in the Llaima system. Each recharge event destabilizes the plagioclase in equilibrium with the resident crystal mush melt and stabilizes relatively An-rich plagioclase, as is recorded by the numerous resorption zones. Lavas typically have ∼15-20 vol. % more phenocrysts than the tephra. Differences in plagioclase and olivine textures and zoning, combined with different phenocryst contents, indicate that a greater volume fraction of recharge magma is present in the explosively erupted magma than in subsequent effusively erupted magma. We propose that Strombolian paroxysms at Volcán Llaima are triggered by interactions with large volume fractions of recharge magma, which decrease the bulk viscosity and increase the volatile contents of the erupted magmas, leading to the conditions required for the fragmentation of basaltic-andesite. Lava effusion ensues from reduced interactions with the recharge magma, after it has partially degassed and crystallized, thereby impeding rapid ascent. This process could be operating at other steady-state basaltic volcanoes, wherein shallow reservoirs are periodically refilled by fresh, volatile-rich magma

Enseigner au collégial, une profession à partager

Titre de l'écran-titre (visionné le 22 nov. 2007).Également disponible en format papier