Cette thèse est une contribution à la réflexion du rôle dynamique du Canada dans le soutien international au développement démocratique. Elle dresse un bilan des actions menées, entre 2006 et 2012, par l’Agence canadienne de développement international (ACDI), principal organe d’aide du Canada, en appui à la gouvernance démocratique au Mali, pays de concentration de l’aide canadienne. Elle soutient que les motivations de la coopération canadienne au Mali sont ambiguës et que les résultats sont mitigés. Les progrès accomplis ces dernières années ont été fragilisés par les conséquences de la crise sécuritaire et politique de 2012 et la suspension de l’aide bilatérale canadienne a compromis l’évolution dynamique de ses projets. La démarche analytique combine une approche constructiviste critique avec une analyse inductive pour l’interprétation des motivations ambiguës et des résultats mitigés obtenus. L’étude a été conduite au moyen d'analyses documentaires et d'entretiens semi-directifs approfondis auprès d’une dizaine de personnes ressources.

<p><a></a><a>The visual system is capable of interpreting immense sensory complexity, allowing us to quickly identify behaviorally relevant stimuli in the environment. It performs this task with a hierarchical organization that works to detect, relay, and integrate visual stimulus features into an interpretable form. To understand the complexities of this system, visual neuroscientists have benefited from the many advantages of using mice as visual models. Despite their poor visual acuity, these animals possess surprisingly complex visual systems, and have been instrumental in understanding how visual features are processed in the primary visual cortex (V1). However, a growing body of literature has shown that primary sensory areas like V1 are capable of more than basic feature detection, but can express neural activity patterns related to learning, memory, categorization, and prediction. </a></p> <p>Visual experience fundamentally changes the encoding and perception of visual stimuli at many scales, and allows us to become familiar with environmental cues. However, the neural processes that govern visual familiarity are poorly understood. By exposing awake mice to repetitively presented visual stimuli over several days, we observed the emergence of low frequency oscillations in the primary visual cortex (V1). The oscillations emerged in population level responses known as visually evoked potentials (VEPs), as well as single-unit responses, and were not observed before the perceptual experience had occurred. They were also not evoked by novel visual stimuli, suggesting that they represent a new form of visual familiarity in the form of low frequency oscillations. The oscillations also required the muscarinic acetylcholine receptors (mAChRs) for their induction and expression, highlighting the importance of the cholinergic system in this learning and memory-based phenomenon. Ongoing visually evoked oscillations were also shown to increase the VEP amplitude of incoming visual stimuli if the stimuli were presented at the high excitability phase of the oscillations, demonstrating how neural activity with unique temporal dynamics can be used to influence visual processing.</p> <p>Given the necessity of perceptual experience for the strong expression of these oscillations and their dependence on the cholinergic system, it was clear we had discovered a phenomenon grounded in visual learning or memory. To further validate this, we characterized this response in a mouse model of Fragile X syndrome (FX), the most common inherited form of autism and a condition with known visual perceptual learning deficits. Using a multifaceted experimental approach, a number of neurophysiological differences were found in the oscillations displayed in FX mice. Extracellular recordings revealed shorter durations and lower power oscillatory activity in FX mice. Furthermore, we found that the frequency of peak oscillatory activity was significantly decreased in FX mice, demonstrating a unique temporal neural impairment not previously reported in FX. In collaboration with Dr. Christopher J. Quinn at Purdue, we performed functional connectivity analysis on the extracellularly recorded spikes from WT and FX mice. This analysis revealed significant impairments in functional connections from multiple layers in FX mice after the perceptual experience; some of which were validated by another graduate student (Qiuyu Wu) using Channelrhodopsin-2 assisted circuit mapping (CRACM). Together, these results shed new light on how visual stimulus familiarity is differentially encoded in FX via persistent oscillations, and allowed us to identify impairments in cross layer connectivity that may underlie these differences. </p> <p>Finally, we asked whether these oscillations are observable in other brain areas or are intrinsic to V1. Furthermore, we sought to determine if the oscillating unit populations in V1 possess uniform firing dynamics, or contribute differentially to the population level response. By performing paired recordings, we did not find prominent oscillatory activity in two visual thalamic nuclei (dLGN and LP) or a nonvisual area (RSC) connected to V1, suggesting the oscillations may not propagate with similar dynamics via cortico-thalamic connections or retrosplenial connections, <a>but may either be uniquely distributed across the visual hierarchy or predominantly</a> restricted to V1. Using K-means clustering on a large population of oscillating units in V1, we found unique temporal profiles of visually evoked responses, demonstrating distinct contributions of different unit sub-populations to the oscillation response dynamics.</p>

<div>The visual system is responsible for processing visual input, inferring its environmental causes, and assessing its behavioral significance that eventually relates to visual perception and guides animal behavior. There is emerging evidence that visual perception does not simply mirror the outside world but is heavily influenced by contextual information. Specifically, context might refer to the sensory, cognitive, and/or behavioral cues that help to assess the behavioral relevance of image features. One of the most famous examples of such behavior is visual or optical illusions. These illusions contain sensory cues that induce a subjective percept that is not aligned with the physical nature of the stimulation, which, in turn, suggests that a visual system is not a passive filter of the outside world but rather an active inference machine.</div><div>Such robust behavior of the visual system is achieved through intricate neural computations spanning several brain regions that allow dynamic visual processing. Despite the numerous attempts to gain insight into those computations, it has been challenging to decipher the circuit-level implementation of contextual processing due to technological limitations. These questions are of great importance not only for basic research purposes but also for gaining deeper insight into neurodevelopmental disorders that are characterized by altered sensory experiences. Recent advances in genetic engineering and neurotechnology made the mouse an attractive model to study the visual system and enabled other researchers and us to gain unprecedented cellular and circuit-level insights into neural mechanisms underlying contextual processing.</div><div>We first investigated how familiarity modifies the neural representation of stimuli in the mouse primary visual cortex (V1). Using silicon probe recordings and pupillometry, we probed neural activity in naive mice and after animals were exposed to the same stimulus over the course of several days. We have discovered that familiar stimuli evoke low-frequency oscillations in V1. Importantly, those oscillations were specific to the spatial frequency content of the familiar stimulus. To further validate our findings, we investigated how this novel form of visual learning is represented in serotonin-transporter (SERT) deficient mice. These transgenic animals have been previously found to have various neurophysiological alterations. We found that SERT-deficient animals showed longer oscillatory spiking activity and impaired cortical tuning after visual learning. Taken together, we discovered a novel phenomenon of familiarity-evoked oscillations in V1 and utilized it to reveal altered perceptual learning in SERT-deficient mice.</div><div>16</div><div>Next, we investigated how spatial context influences sensory processing. Visual illusions provide a great opportunity to investigate spatial contextual modulation in early visual areas. Leveraging behavioral training, high-density silicon probe recordings, and optogenetics, we provided evidence for an interplay of feedforward and feedback pathways during illusory processing in V1. We first designed an operant behavioral task to investigate illusory perception in mice. Kanizsa illusory contours paradigm was then adapted from primate studies to mouse V1 to elucidate neural correlates of illusory responses in V1. These experiments provided behavioral and neurophysiological evidence for illusory perception in mice. Using optogenetics, we then showed that suppression of the lateromedial area inhibits illusory responses in mouse V1. Taken together, we demonstrated illusory responses in mice and their dependence on the top-down feedback from higher-order visual areas.</div><div>Finally, we investigated how temporal context modulates neural responses by combining silicon probe recordings and a novel visual oddball paradigm that utilizes spatial frequency filtered stimuli. Our work extended prior oddball studies by investigating how adaptation and novelty processing depends on the tuning properties of neurons and their laminar position. Furthermore, given that reduced adaptation and sensory hypersensitivity are one of the hallmarks of altered sensory experiences in autism, we investigated the effects of temporal context on visual processing in V1 of a mouse model of fragile X syndrome (FX), a leading monogenetic cause of autism. We first showed that adaptation was modulated by tuning properties of neurons in both genotypes, however, it was more confined to neurons preferring the adapted feature in FX mice. Oddball responses, on the other hand, were modulated by the laminar position of the neurons in WT with the strongest novelty responses in superficial layers, however, they were uniformly distributed across the cortical column in FX animals. Lastly, we observed differential processing of omission responses in FX vs. WT mice. Overall, our findings suggest that reduced adaptation and increased oddball processing might contribute to altered perceptual experiences in FX and autism.</div>

Les liaisons bimétalliques en acier inoxydable (LBM inox) permettent, au sein des réacteurs nucléaires français actuels, de connecter les gros composants en acier ferritique faiblement allié (cuve, pressuriseur, générateur de vapeur) à la tuyauterie du circuit primaire en acier austénitique inoxydable. De par leurs microstructure et propriétés mécaniques hétérogènes, ces liaisons sont des zones dites "sensibles" pour l'intégrité des structures et il est donc indispensable de caractériser leur tenue mécanique dans les situations de fonctionnement nominal et accidentelles. Ce travail de thèse a pour objectif d'évaluer le risque d'amorçage fragile de la LBM inox dans le haut de la transition fragile-ductile à l'aide d'un critère adapté. Les microstructures au voisinage de l'interface entre l'acier ferritique et le beurrage austénitique ont tout d’abord été caractérisées, et un liseré martensitique d’épaisseur variable ainsi qu’une couche entièrement austénitique ont été observés. Ces deux couches, qui sont le siège d’une intense précipitation de carbures pendant le traitement thermique de détensionnement, forment ensemble une couche dure de martensite et d’austénite carburées potentiellement fragile. Le comportement mécanique de l’ensemble de la LBM inox a ensuite été étudié à 20°C et à -175°C, et des lois de comportement élasto-plastiques isotropes ont été identifiées pour les différentes couches macroscopiques à partir d’essais de traction sur des éprouvettes multi-matériaux travers-joint à diamètre variable. Le comportement mécanique de la couche dure a, quant à lui, été caractérisé à partir d’essais in-situ sur des micro-éprouvettes usinées au FIB et testées à l’aide d’une micro-machine de traction développée dans cette thèse. Une étude des mécanismes de rupture de la LBM inox dans le domaine de la transition fragile-ductile a par ailleurs été réalisée à partir d’essais sur éprouvettes CT et a mis en évidence une fragilité de l’interface MA (entre martensite et austénite) liée à un mécanisme de rupture intergranulaire amorcée sur les carbures et systématiquement activé pour des fronts de préfissure traversant la couche dure. Une modélisation par éléments finis des essais a permis d’analyser les champs de contrainte sur l’interface MA et d’identifier un modèle de Weibull linéique à 3 paramètres basé sur une contrainte seuil et une distance seuil pour les éprouvettes CT. Finalement, l’effet du vieillissement thermique sur les LBM inox a été étudié à partir d’un traitement thermique de 10 000h à 400°C et un durcissement des couches austénitiques résultant d’un mécanisme de décomposition spinodale de la ferrite résiduelle a été mis en évidence à partir d’essais de traction. L’analyse des mécanismes de rupture à l’état vieilli a également montré que ce durcissement provoque une augmentation d’environ 30°C de la température de transition associée à la rupture intergranulaire de l’interface MA. / Stainless steel dissimilar metal welds (SS DMW) are widely used within the French nuclear power plants where they connect the main components (pressure vessel, pressurisor, steam generator) made of low-alloy ferritic steel to the primary circuit pipes made of austenitic stainless steel. Because of their heterogeneous microstructure and mechanical properties, these junctions are critical components for the structure integrity and their fracture resistance has to be demonstrated for all the nominal or accidental operating conditions. This PhD work aims at building a model to evaluate the risk of brittle fracture of the SS DMW in the upper shelf of the brittle-to-ductile transition range. The observation of the microstructures around the fusion line revealed a martensitic layer and a fully austenitic zone, which undergo an important carbides precipitation during the post-weld heat treatment and form a narrow hard layer of carburized martensite and austenite. The mechanical behavior of the SS DMW was then characterized at 20°C and -175°C and isotropic elastoplastic constitutive laws were determined for each macro/mesoscopic layer of the weld from tensile tests on crossweld specimens with variable diameters. The mechanical behavior of the narrow hard layer was also studied with micro tensile tests on specimens extracted by FIB micro processing and tested using an in-situ tensile testing device developed during the PhD. Furthermore, fracture toughness tests were carried out on CT specimens in the brittle-to-ductile temperature range and helped identify the MA interface (between martensite and austenite) as the weakest region in the SS DMW because of an intergranular fracture mechanism initiated at the carbides-rich interface. This mechanism was consistently observed for specimens with fatigue precrack fronts in the hard layer. The stress distributions on the MA interface calculated from the FE numerical simulation of these tests were then analysed and a 1D 3 parameters Weibull model based on a threshold stress and a threshold length was identified for the CT specimens. Finally, the effect of thermal ageing on the SS DMW was explored with a thermal ageing treatment of 10000h at 400°C and a hardening of the austenitic layers was measured by tensile tests and was associated to a spinodal decomposition mechanism of the residual ferrite. The fracture mechanisms of the SS DMW were also analysed in the aged state and showed that this hardening caused an increase of the transition temperature associated with the intergranular fracture of the MA interface by about 30°C.

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[pt] Narrativas acerca de intervenções de infraestrutura e de segurança nas favelas do Rio de Janeiro são construídas em torno da chegada do Estado onde ele supostamente estava ausente com o objetivo de resolver o problema favela, tanto em termos da dita informalidade e precariedade, quanto em termos da suposta marginalidade dos seus habitantes, e integrálas ao restante da cidade como forma de superar a cidade partida. A concretude de sucessivas intervenções de infraestrutura e as frequentes intervenções de segurança, no entanto, permitem o questionamento desse mito da ausência do Estado nas favelas, enquanto a proximidade geográfica entre favela e asfalto, a circulação do espaço e a mão de obra que sustenta as relações na cidade empreendidas por seus moradores, e toda a sua vibrante produção social e cultural permitem o questionamento do mito da cidade partida. A principal pergunta que se coloca, portanto, é como o Estado brasileiro atua sobre esses espaços e corpos onde tradicionalmente é visto como ausente e frágil. Para tal, o presente trabalho partirá da literatura de Relações Internacionais para entender a relação entre discursos de falência, fragilidade, desordem e práticas específicas de intervenção e reconstrução no âmbito global (a partir dos conceitos de Estado falido, peacebuilding e nexo segurança-desenvolvimento), passando por uma literatura que mobiliza esses conceitos para pensar o urbano, pensar a cidade como um problema e suas possíveis soluções (em termos de peacebuilding urbano, cidades frágeis, urbanismo militar). Então, a partir da literatura brasileira especializada em favelas, questionará a construção da favela enquanto problema e as soluções articuladas por meio de formas específicas de presença do Estado, de forma a repactuar o problema como sendo um problema da atuação seletiva e imperfeita, muitas vezes racista, do Estado nesses espaços. Finalmente, a partir das contribuições e insuficiências dos conceitos e literaturas anteriores, o trabalho refletirá como as intervenções estatais, com foco em intervenções de infraestrutura e segurança, materializam-se especificamente no Complexo da Maré, reproduzindo exclusões e desigualdades, e como os moradores e organizações locais resistem a elas. / [en] Narratives about infrastructure and security interventions in Rio de Janeiro favelas are often built around the arrival of the State in places where it was supposedly absent, aiming at resolving the favela problem, both in terms of their informality and precariousness, and in terms of the marginality and criminality, and at integrating them with the formal neighborhoods so as to overcome the divided city. The concrete reality of successive infrastructure and security interventions, however, allows us to question the myth of State absence in favelas, whereas the territorial proximity between favelas and the rest of the city, their residents labor and circulation across the city and their vibrant social and cultural production allow us to question the myth of the divided city. Therefore, the main question posed is how the Brazilian State acts upon these spaces and bodies where it is traditionally seen as fragile and absent. With this aim, the presente work mobilizes International Relations literature to understand the relation between failure, fragility, disorder and practices of intervention in the global realm (which involves concepts such as failed State, peacebuilding and security-development nexus), and also literatures which mobilize such concepts in order to understand the urban realm, to understand cities as problems and their solutions (in terms of urban peacebuilding, fragile cities, military urbanism). Then, departing from a favela-focused Brazilian literature, the work questions the myth of the favela problem and also the solutions which are articulated in terms of specific forms of state presence, so as to reframe the problem as a problem of selective and imperfect, often racist, state actions. Finally, building upon those literatures contributions and limitations, the work reflects upon how state interventions, especially insfrastructure and security interventions, materialize in Complexo da Maré, reproducing exclusion and inequality, and how residents and local organizations resist those interventions.

Univ., Diss.--Zugl.: Zürich. / Erscheint vorauss. Oktober 2008.

This dissertation examines the history of the creation and development of the concept of anticipation, a pattern of heredity found in several diseases (e.g. Huntington’s disease and myotonic dystrophy), in which an illness manifests itself earlier and often more severely in successive generations. It reconstructs major arguments in twentieth-century debates about anticipation and analyzes the relations between different research communities and schools of thought. Developments in cutting-edge medicine, biology, and genetics are analyzed; many of these developments were centered in Britain, but saw significant contributions by people working in France, Germany, Switzerland, the Netherlands and North America. Chapter one traces precursor notions in psychiatric and hereditarian thought from 1840 to the coining of the term ‘anticipation’ by the ophthalmologist Edward Nettleship in 1905. Key roles in the following chapters are played by several figures. Prior to World War II, these include: the neuropathologist F.W. Mott, whose advocacy during 1911- 1927 led to anticipation being called “Mott’s law”; the biometrician and eugenicist Karl Pearson, who opposed Mott on methodological and political grounds; and two politically and theoretically opposed Germans – Ernst Rüdin, a leading psychiatrist and eugenicist who came to reject anticipation, and Richard Goldschmidt, a geneticist who offered a peculiar Mendelian explanation. The British psychiatrist and human geneticist, Lionel Penrose, makes a first interwar appearance, but becomes crucial to the story after World War II due to his systematic dismissal of anticipation, which discredited the notion on orthodox Mendelian grounds. The final chapters highlight the contributions of Dutch neurologist Christiaan Höweler, whose 1980s work demonstrated a major hole in Penrose’s reasoning, and British geneticist Peter Harper, whose research helped demonstrate that expanding trinucleotide repeats accounted for the transgenerational worsening without contradicting Mendel and resurrected anticipation as scientifically legitimate. Reception of the concept of anticipation is traced across the century through the examination of textbooks used in different fields. This dissertation argues against established positions regarding the history of the concept, including claims that anticipation’s association with eugenics adequately explains the rejection of the notion after 1945. Rejected, in fact, by many eugenicists from 1912, anticipation was used by physicians until the 1960s.