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Cette thèse constitue une analyse de la dynamique du bois mort en rivière par une approche de bilan ligneux multi-scalaire dans une rivière semi-alluviale de région froide: la rivière Saint-Jean, Gaspé. L’étude de la variabilité spatiale et temporelle de la dynamique du bois mort a été réalisée grâce à une approche méthodologique combinant quatre années de terrain et par l’analyse de documents historiques. Les rivières de la péninsule gaspésienne produisent et transportent annuellement de grandes quantités de bois mort. Cette production provient à la fois de la puissance spécifique élevée des cours d’eau et de berges composées de sédiments peu cohésifs et comportant une ripisylve arborescente généralement dense. Jusqu’en 2015, le delta de la rivière Saint-Jean comportait plusieurs embâcles de bois de très grandes tailles. Ces embâcles se mettent en place depuis les années 1960, ils représentent une opportunité unique de quantifier et d’appliquer un budget ligneux pour cerner les variables clefs liées à la dynamique du bois mort à multiples échelles spatiales et temporelles.Nos résultats montrent que la quasi-totalité des bois morts en rivière est produite par la migration latérale et par l’influence de la morphologie. Au niveau des accumulations dans le corridor fluvial, deux zones accumulent la majorité des bois et ces premiers résultats montrent une mobilité importante qui peut varier fortement d'une année à l'autre. Au niveau de la mobilité, l’analyse d’imagerie vidéo de trois évènements différents ont montré que l’intensité (nombre de bois par minute) du transport de bois pouvait être jusqu’à dix fois supérieures durant un évènement avec débâcle mécanique glacielle, comparativement à un évènement hydroclimatique en eau libre.Finalement, nous avons réalisé une analyse par bilans ligneux et une analyse de la trajectoire éco-hydrophormologique sur une période de plus de 50 ans. Nous avons quantifié chaque composante (intrant, accumulée et sortie) d'un budget ligneux à multiples échelles spatio-temporelles. Autant à l’échelle interannuelle, qu’à l’échelle décennale, la dynamique du bois mort comporte des périodes où l’entrée de bois, le stockage et la mobilité diffèrent selon les contextes éco-hydromorphologiques. La trajectoire éco-hydromorphologiques suggère une augmentation de la dynamique fluviale en raison d'un changement significatif dans l'hydrologie conduisant à une plus grande production et mobilité des bois morts et par l'augmentation des volumes accumulés dans le corridor de la RSJ depuis 2004. This thesis is an analysis of the dynamics of large wood in river by a multi-scale large wood budget approach in a semi-alluvial river of cold regions: the Saint-Jean River, Gaspé. The study of the spatial and temporal variability of the dynamics of large wood was carried out through a methodological approach combining four years of field and by analyzing historical documents. The rivers of the Gaspé Peninsula produce annually and carry large amounts of large wood. This production comes from the high specific power of rivers and by banks composed of noncohesive sediment and having a generally dense riparian forest tree. Until 2015, the Delta of the Saint-Jean River had several very large jams. These jams are put in place since the 1960s, they represent a unique opportunity to quantify and apply a wood budget and to identify key variables related to the dynamics of large wood at multiple spatial and temporal scales.Our results show that almost all large wood in river is produced by lateral migration and by the influence of the morphology. For the accumulations in the river corridor, two areas accumulate the majority of wood and these first results show a significant mobility, which can fluctuate substantially from year to year. In terms of mobility, video analysis of three different events showed that the intensity of the transport (number of large wood per minute) can be higher to ten times during an event with mechanical ice-breakup, compared to an open water.hydroclimatic event.Finally, we conducted an analysis by large wood budget and analysis of eco-hydromorphological trajectory over more than 50 years. We quantified each component (input, output and accumulated) of a large wood budget at multiple spatial and temporal scales. At the interannual scale or decadal, scale, the dynamics of large wood have periods when the input, storage and mobility of large wood differ according to eco-hydromorphological contexts. The eco-hydromorphological trajectory suggests an increase in river dynamics due to a significant change in the hydrology, resulting in higher production and mobility of large wood and increased in volumes accumulated in the corridor of the Saint-Jean River since the last decade.

This experiment explores how changes in soundpost height affect the perceptual qualities of the violin and whether there is a threshold of change below which players and luthiers do not perceive differences. A violin installed with a height-adjustable carbon fibre soundpost was employed. The experiment was designed as a sequence of playing tests. An experimenter was present to change the soundpost height. Thirteen professional violinists and six luthiers participated. The experiment involved two phases. During the first phase, subjects played and described their feelings about the violin with different soundpost settings in order to find their optimal soundpost height. During the second phase, the experimenter randomly increased, decreased or did not change the soundpost height in ten trials within a range of approximately ±0.1 mm around their optimal height. For each trial, subjects were asked to play the violin, comparing it with the previous setting, and to decide whether they were the same or different. Initial results indicate that each subject's optimal soundpost height varies within an interquartile range of 0.3 mm and the smallest height variation that could be recognized above chance level is about 0.04 mm.

This article is a summary of recent Open Access activity in Canada, focusing on policies and mandates, repositories, and initiatives in libraries.

The behavior of rational selfish agents has been classically studied in the framework of strategic games in which each player has a set of possible actions, players choose actions simultaneously and the payoff for each player is determined by the matrix of the game. However, in many applications, players choose actions asynchronously, and simultaneity of this process is not guaranteed: it is possible that a player learns the action of another player before making its choice. Delays of choices are controled by the adversary and each player can only secure the worst-case payoff over the adversary's decisions. In this paper we consider such asynchronous versions of arbitrary two-person strategic games and we study how the presence of the asynchronous adversary influences the behavior of the players, assumed to be selfish but rational. We concentrate on deterministic (pure) strategies, and in particular, on the existence and characteristics of pure Nash equilibria in such games. It turns out that the rational behavior of players changes significantly if the decision process is asynchronous. We show that pure Nash equilibria often exist in the asynchronous version of the game even if there were no such equilibria in the synchronous game. We also show that a mere threat of asynchrony in the game may make social optimum a rational choice while it was not rational in the synchronous game.

This paper addresses indicators of the performance of the Vancouver human health biotechnology cluster.

The fate and transport of methylmercury (MeHg) were studied in a small boreal catchment. Hydrological processes largely govern the magnitude of the flux of MeHg. Seasonal and inter-annual variability in hydrology produce variable source strengths of MeHg throughout the catchment. The mass flux of MeHg within, and from the catchment is dependent on the mass flux of water and the relative placement of landscape units in the catchment hydrological cascade. Hydrology also governs the maintenance of the methylating environments in the catchment. Specifically, hydrological processes maintain zones of anoxia in both the catchment uplands and peatlands that support obligate anaerobic sulphate-reducing bacteria. In addition, groundwater flow paths are an essential control on the delivery of sulphate to these bacteria that facilitate in situ mercury methylation. Keywords: methylmercury, methylation, hydrology, boreal catchment, peatland, Ontario, Canada

We prove the Haagerup property for an infinite discrete group constructed using surgery on a Euclidean Tits building of type A ˜ 2 .

L'étude de l'Univers primordial adresse quelques-unes des questions les plus fondamentales de la physique théorique. Cette thèse a pour objet l'exploration de trois aspects principaux de la cosmologie primordiale. Dans un premier temps, nous discutons d'une alternative au paradigme scientique qu'est le modèle du Big Bang. A savoir, nous explorons un modèle d'univers à rebond qui évite la singularité initiale du Big Bang. Nous commencerons dans l'introduction par revoir les éléments de base nécessaires à la compréhension de la cosmologie. A la suite de quoi, nous montrerons un modèle spécifique d'Univers à rebond contenant des champs additionnels particuliers en complément des champs présents habituellement. Ces nouveaux champs proviennent de ce qui s'appelle le modèle "Lee-Wick" de la physique des particules. En particulier, nous prouvons qu'un univers à rebond dans ce contexte est instable lorsque l'on ajoute une composante de radiation en plus de la matière. Dans la seconde partie, nous considérons la production de particules via un phénomène de résonance paramétrique durant la phase de "préchauffement", a la fin de l'inflation cosmologique. Plus précisément, nous prouvons que dans le cas où l'inflation a une limite de vitesse, les termes cinétiques non-canoniques décrivant n'importe quel Lagrangien effectif n'améliorent pas la production de particules. Finalement, le dernier sujet aborde concerne les défauts topologiques pendant la transition de phase de la chromodynamique quantique. A savoir, nous étudions les cordes cosmiques provenant des champs de pions présents dans le modèle standard de la physique des particules et trouvons un méchanisme pour les stabiliser. Nous prouvons alors qu'un bain thermique de photons en contact avec ces cordes réduit la variété du vide à un cercle. Cela a pour effet d'autoriser la présence de "cordes pioniques" topologiquement stables. The study of the Early Universe raises some of the most fundamental questions in theoretical physics. This thesis explores three main aspects of early universe cosmology. The first part discusses alternatives to the Big Bang scenario which is the current paradigm of cosmology. Namely, it discusses bouncing universe models where the initial Big Bang singularity is replaced by a finite size universe. After reviewing the necessary cosmology background in the introduction, we show a specific model of a bouncing universe that contains additional "Lee-Wick fields", partners to the standard fields. In particular we prove that a Lee-Wick matter bounce is unstable when one adds radiation to matter. In the second part of this thesis, we consider particle production via parametric resonance during preheating, at the end of cosmological inflation. Specifically, we prove that in the case of a speed-limited inflaton, non-canonical kinetic terms used to described any effective Lagrangian do not enhance particle production. Finally, the last topic involves topological defects during the Quantum Chromodynamics phase transition. Namely, we study cosmic strings coming from pion fields present in the Standard Model of particle physics and find a mechanism to stabilize them. We show how a thermal bath of photons reduces the effective vacuum manifold to a circle and thus allows the presence of topologically stable pion strings.