On observe des anomalies d'abondances en surface de nombreuses étoiles A (d'amas et du champ). Ces anomalies d'abondances sont générées par la diffusion microscopique et peuvent etre modulées par l'action d'autres processus de m´elange, incluant la convection, le méange rotationnel, la perte de masse, etc. Ces étoiles désignées chimiquement particulières montrent typiquement des sous-abondances en calcium et/ou en scandium ainsi que des surabondances en éléments du pic du fer et en éléments plus lourds. Les étoiles A non magnétiques de ce type sont classifiées Am.<br />En observant en particulier des étoiles A et F dans des amas ouverts, on peut obtenir des informations additionnelles qui facilitent la comparaison aux mod`eles, soient la composition chimique initiale et l'age de ces étoiles. Ainsi en déterminant la composition chimique des étoiles A/F dans plusieurs amas ouverts d'ages différents, on peut suivre l'évolution de la composition chimique de surface et contraindre les modèles évolutifs au niveau des processus de transport.<br />Dans cette thèse, j'expose l'analyse de la composition chimique d'échantillons d'étoiles A et F dans deux amas ouverts d'ages différents: les Pléiades (100 Myrs) et Coma Berenices (450 Myrs). Ce travail repose sur des observations que j'ai menées avec les trois spectrographes AURELIE, ELODIE et SOPHIE a l'Observatoire de Haute-Provence (OHP). La méthode des spectres synthétiques, basée sur des modèles d'atmosphères d'ATLAS9-12, a été utilisée afin de déterminer les abondances de 22 éléments. Ces observations sont ensuite comparées aux prédictions des modèles évolutifs de Montréal. Les résultats démontrent l'existence de processus hydrodynamiques dans les zones radiatives de ces étoiles et qui contrebalancent les effets de la diffusion microscopique.

A investigação do romance Girlfriend in a Coma permitiu perceber alguns elementos centrais que estruturam a obra como mito e paródia. O mundo ficcional é caracterizado por uma sociedade à beira de um colapso devido a sua incapacidade de mudar seu comportamento e sequer consegue perceber o que está errado. Na narrativa são utilizados recursos estéticos identificados com o realismo maravilhoso, pois, juntamente com a descrição de eventos coerentes com a racionalidade humana, há eventos sobrenaturais realizados pelo divino. Nesta narrativa, a ideologia do trabalho árduo como estruturador da vida em uma sociedade democrática e capitalista é esfacelado em vista dos terríveis efeitos sentidos pelos personagens: trabalho extenuante, drogadição, anorexia e individualismo. Com o uso de teoria da narrativa e pós-modernista, argumenta-se que este romance é um ‗mito do novo mundo‘ ao fazer uso da paródia como forma de contestar meta-narrativas, e ao propor novas cosmogonias baseadas na experiência pós-colonial Canadense. / The investigation of the novel Girlfriend in a Coma revealed some central elements that structure this work as myth and parody. The fictional world is characterized by a society incapable of changing its behavior or even realizing what is wrong with it. In the narrative some aesthetic resources are used which are related to magic realism because, along with the description of events coherent with human rationality, there are supernatural events performed by the divine. In this narrative, the ideology of hard work as the main structure of life in a democratic capitalist society is unveiled, taking into account some terrible effects felt by the characters, such as: overworking, drug addiction, anorexia and individualism. With the use of narrative theory and postmodernist theory, it is argued that this novel is a ‗new world myth‘ because it makes use of parody as a way to refute masternarratives and to suggest new cosmogonies based on the Canadian post-colonial experience.

A investigação do romance Girlfriend in a Coma permitiu perceber alguns elementos centrais que estruturam a obra como mito e paródia. O mundo ficcional é caracterizado por uma sociedade à beira de um colapso devido a sua incapacidade de mudar seu comportamento e sequer consegue perceber o que está errado. Na narrativa são utilizados recursos estéticos identificados com o realismo maravilhoso, pois, juntamente com a descrição de eventos coerentes com a racionalidade humana, há eventos sobrenaturais realizados pelo divino. Nesta narrativa, a ideologia do trabalho árduo como estruturador da vida em uma sociedade democrática e capitalista é esfacelado em vista dos terríveis efeitos sentidos pelos personagens: trabalho extenuante, drogadição, anorexia e individualismo. Com o uso de teoria da narrativa e pós-modernista, argumenta-se que este romance é um ‗mito do novo mundo‘ ao fazer uso da paródia como forma de contestar meta-narrativas, e ao propor novas cosmogonias baseadas na experiência pós-colonial Canadense. / The investigation of the novel Girlfriend in a Coma revealed some central elements that structure this work as myth and parody. The fictional world is characterized by a society incapable of changing its behavior or even realizing what is wrong with it. In the narrative some aesthetic resources are used which are related to magic realism because, along with the description of events coherent with human rationality, there are supernatural events performed by the divine. In this narrative, the ideology of hard work as the main structure of life in a democratic capitalist society is unveiled, taking into account some terrible effects felt by the characters, such as: overworking, drug addiction, anorexia and individualism. With the use of narrative theory and postmodernist theory, it is argued that this novel is a ‗new world myth‘ because it makes use of parody as a way to refute masternarratives and to suggest new cosmogonies based on the Canadian post-colonial experience.

The study aimed at giving a thick description of African families' experiences, views, cultural beliefs and interpretations of traumatic brain injury (TBI), and making recommendations for rehabilitation. It was conducted from the qualitative research paradigm, adopting a phenomenological research method. Twenty-two pairs of participants (patients and their caregivers )were interviewed about their perception of TBI. The semi-structured interviews were conducted at the participants' homes in Sesotho, and where necessary in their home languages. The consequences of TBI were found to follow universal trends (Oddy, 1984). However, participants' perceptions, as shaped by their experiences, views and cultural beliefs, were found to be unique. On analysing the gathered data, using inductive data analysis, it was found that African families' interpretations of TBI were based on beliefs about witchcraft, thwasa, Satanism, ancestral anger and God's wish. Based on these findings, rehabilitation services in the form of education, advocacy, networking and family therapy are recommended. / Psychology / M.A.(Clinical Psychology)

The main aim of this work is, to explore how basal stimulation affects the process of coma vigil in patients, when carried out only by trained practitioners. And also, to explore how basal stimulation affects the process of coma vigil in patients, when carried out by family members with the assistance of practitioners. To achieve the aim, a qualitative research will be used in the form of case studies and interviews. The research team involves patients in coma vigil, family members and practitioners performing basal stimulation to affected patients. The purpose of this assignment is to prove that the involvement of family members in the process of basal stimulation significantly improves the effectiveness of the treatment. In our profession, we can often see patients with impairments of perception, movement or other disorders. While a human body is in a coma, it can still perceive emotions and other surrounding influences that affect the body. To improve the quality of care that these patients receive, the concept of basal stimulation serves as one of the alternatives of treatment. The implementation of this concept shows positive effects on the overall health of the client when in cooperation with family members. The results of this assignment may be used as a foundation when producing seminars and procedures that serve to educate the healthcare staff and families, in order to achieve the best results in a given issue.

A investigação do romance Girlfriend in a Coma permitiu perceber alguns elementos centrais que estruturam a obra como mito e paródia. O mundo ficcional é caracterizado por uma sociedade à beira de um colapso devido a sua incapacidade de mudar seu comportamento e sequer consegue perceber o que está errado. Na narrativa são utilizados recursos estéticos identificados com o realismo maravilhoso, pois, juntamente com a descrição de eventos coerentes com a racionalidade humana, há eventos sobrenaturais realizados pelo divino. Nesta narrativa, a ideologia do trabalho árduo como estruturador da vida em uma sociedade democrática e capitalista é esfacelado em vista dos terríveis efeitos sentidos pelos personagens: trabalho extenuante, drogadição, anorexia e individualismo. Com o uso de teoria da narrativa e pós-modernista, argumenta-se que este romance é um ‗mito do novo mundo‘ ao fazer uso da paródia como forma de contestar meta-narrativas, e ao propor novas cosmogonias baseadas na experiência pós-colonial Canadense. / The investigation of the novel Girlfriend in a Coma revealed some central elements that structure this work as myth and parody. The fictional world is characterized by a society incapable of changing its behavior or even realizing what is wrong with it. In the narrative some aesthetic resources are used which are related to magic realism because, along with the description of events coherent with human rationality, there are supernatural events performed by the divine. In this narrative, the ideology of hard work as the main structure of life in a democratic capitalist society is unveiled, taking into account some terrible effects felt by the characters, such as: overworking, drug addiction, anorexia and individualism. With the use of narrative theory and postmodernist theory, it is argued that this novel is a ‗new world myth‘ because it makes use of parody as a way to refute masternarratives and to suggest new cosmogonies based on the Canadian post-colonial experience.

Repeated cold exposures and warmer winter temperatures might negatively affect insects by depleting stored fuel reserves. I researched the effects of fluctuating thermal regimes on two species of solitary mason bees (Osmia albiventris and O. lignaria) by quantifying mass loss and reserves of lipids, free sugars, and glycogen after experimental temperature treatments during early spring. In a second season, I quantified mass loss, time to emergence, and time to recover from chill coma after bees had been exposed to one of two spring-time temperature regimes. I found that warmer temperatures in combination with greater temperature variability increases mass loss and the depletion of fuel reserves. Additionally, my results suggest that accelerated bee emergence helps to mitigate mass loss. Overall, these bees appear resilient in the face of changing spring temperatures. Résumé: On sait peu sur la façon dont la variabilité environnementale affecte les abeilles solitaires sauvages. Ma recherche a étudié la façon dont les régimes thermiques fluctuants affectent la vigueur de deux espèces d'abeilles solitaires (Osmia albiventris et O. lignaria) en quantifiant la perte de masse ainsi que les réserves métaboliques (lipides, sucres libres, et glycogène) des abeilles suite à des manipulations expérimentales de la température printanière. Dans une deuxième saison, j’ai quantifié la perte de masse, le temps de l'émergence et le temps pour récupérer du coma froid après que les abeilles avaient été exposées à l'un de deux régimes de températures printanières. Mes résultats indiquent que les températures plus chaudes ont tendance à augmenter la perte de masse et des réserves métaboliques lorsqu'elles sont combinées avec une plus grande variabilité. De plus, mes résultats suggèrent que ces abeilles sont résilientes face aux températures printanières changeantes.

In space exploration optical imaging is one of the key measurements conducted, with a vast majority of missions heavily relying on optical data acquisition to examine alien worlds. One such endeavor is ESA’s F-class mission Comet Interceptor, a multi-element spacecraft expected to be launched in 2028. It consists of a primary platform and two sub-spacecraft, one of which carrying the Optical Periscopic Imager for Comets (OPIC). An accurate prediction of the generated imagery is of undeniable importance as mission planning and instrument design strongly depend on the real-world output quality of the camera system. In the case of OPIC, the collected image data will be used to reconstruct three dimensional models of targeted celestial bodies. Furthermore, the sub-spacecraft faces a risk of high velocity dust impacts, leading to a limited number of data samples to be broadcasted back to the primary spacecraft before collision. Testing image prioritization algorithms and reconstruction methods prior to mission start requires accurate computer-generated images. Camera sensors and lens systems are subjected to various optical distortions and aberrations that degrade the final image. Popular render engines model those effects to a certain degree only and as a result produce content that is looking too perfect. While more sophisticated software products exist, they often come with compatibility limitations and other drawbacks. This report discusses the most important optical aberrations, as well as their relevance for optical instruments in space applications with a particular focus on the Comet Interceptor mission. The main part of this work is however the implementation of a dedicated software tool that simulates a variety of optical aberrations complementing the basic camera model of the Blender render engine. While its functionality is mostly demonstrated for OPIC, the software is designed with a broad range of usage scenarios in mind.

La question maîtresse de nos investigations était: Comment les modulations des signaux excitateurs et inhibiteurs mènent à des changements d’état de conscience dans le cerveau – est-ce que l’éveil, le sommeil et le coma sont simplement des points repères dans un continuum allant de la prédominance de l’excitation (pendant l’éveil) à une prévalence ultime de l’inhibition (pendant le coma)? Nous avons tenté de répondre à cette question par une approche à plusieurs niveaux, incluants a) la modulation sub-cellulaire des concentrations ioniques, b) la réactivité intracellulaire à des stimuli externes, et c) des mesures de l’activité globale du cerveau par électroencéphalogramme (EEG). Nos études ont porté exclusivement sur des expériences réalisées in vivo en aigu sur des rats et des chats profondément anesthésiés. Sachant que l’un des facteurs dans la modulation de l’inhibition est la régulation des entrées et sorties du chlore dans les cellules nerveuses, nos investigations ont débuté en questionnant l’influence que cet ion pourrait avoir sur les réponses inhibitrices du réseau. La signalisation inhibitrice basée sur le chlore a pour pré-requis un certain gradient électrochimique entre le cytoplasme et l’espace extracellulaire. Jusqu’à maintenant, il a été largement admis que la diffusion fournissait la force nécessaire à une égale distribution du Cl- dans l’espace extracellulaire et qu’une petite redistribution prenait place après de fortes activités dans le réseau, incluant la signalisation inhibitrice. Par opposition, nous avons montré une différence significative entre les niveaux de Cl- extracellulaire disponibles dans une même région au sein de notre structure cible, la formation hippocampique. Ces résultats suggèrent que le cerveau pourrait employer des mécanismes pour contrer le processus de diffusion et ainsi créer des accumulations spécifiquement régionales d’ions – le plus probablement pour supporter les besoins en approvisionnement. Dans notre modèle, les états de conscience étaient contrôlés par l’induction d’une anesthésie générale; nous avons donc éteint intentionnellement la balance excitation-inhibition des mécanismes de signalisation du cerveau. Des recherches précédentes ont montré que l’anesthésie avec de l’isoflurane amenait l’inconscience par la modulation des neurones thalamocorticaux. Ces neurones agissent en tant que relai pour les signaux sensoriels afférents en route vers le cortex. L’isoflurane hyperpolarise la membrane cellulaire de ces neurones et réduit donc leur réactivité aux signaux synaptiques externes. Il semblerait que la plupart des neurones corticaux ne soient pas soumis à la modulation de l’isoflurane de la même façon. Au contraire, nous avons observé une diminution des réponses inhibitrices aux stimuli afférents dans les neurones corticaux sous l’augmentation des niveaux d’isoflurane, plus spécifiquement pendant les conditions produisant le coma induit par l’anesthésie. En complément à ces micro-mécanismes dynamiques, nous avons aussi investigué les processus globaux au niveau du cerveau entier qui se rapportent à l’inhibition. Nous avons observé 2 nouveaux phénomènes sous ces conditions d’anesthésie : Premièrement, nous avons démontré que même pendant les états comateux, des stimulations sous-liminales pouvaient induire des réponses cérébrales en bouffées, i.e. des bursts. Cependant, cela n’est observé que pendant une certaine fenêtre temporelle de l’anesthésie; lors du passage d’un état similaire au sommeil à l’état de coma. Donc, des réponses synaptiques peuvent en effet être induites même pendant des états comateux. Cette découverte pourrait constituer une pièce vitale du casse-tête pour les cliniciens travaillant avec les patients comateux et tentant de revitaliser leurs circuits cérébraux. En second lieu, nous avons observé un nouveau patron d’activité cérébrale émergeant d’une anesthésie à forte dose d’isoflurane – au-delà des niveaux requis pour l’induction d’une ligne d’EEG isoélectrique. Cette découverte surprenante démontre l’importance de la balance, au niveau d’un circuit, entre l’excitation et l’inhibition, car bien que la ligne isoélectrique semble signifier l’ultime domination de l’inhibition, une forme d’activité excitatrice peut émerger et revitaliser les circuits cérébraux. Nous concluons que l’excitation et l’inhibition pourraient ne pas se balancer dans un mode de tout ou rien et qu’une augmentation de l’inhibition ne cause pas automatiquement le sommeil et/ou le coma. Plutôt, l’excitation et l’inhibition devraient être comprises en tant que processus très localisés pendant lesquels l’activité de quelques neurones peut faire pencher la balance entre les états de conscience. / The guiding question for our investigations was: How do modulations in excitatory and inhibitory signaling lead to changes in the state of consciousness in the brain - are wakefulness, sleep and coma only landmarks on a continuum ranging from predominance of excitation (during wakefulness) to an ultimate prevalence of inhibition (during coma)? We addressed this question by a multilayered approach including a) sub-cellular investigations of modulations of ionic concentrations, b) intracellular responsiveness to excitatory stimuli, and c) EEG measures of whole-brain activity. Our studies were carried out exclusively in acute in vivo experiments on deeply anesthetized rats and cats. Since one of the factors in modulating inhibition is the accessibility of chloride inside- and outside of nerve cells, we began our investigations by asking which influence the availability of this ion might have on inhibitory network responses. Chloride-based inhibitory signaling requires a certain electrochemical gradient between the cytoplasm and the extracellular space as a permissive prerequisite. Thus far, it is widely assumed that diffusion provides a sufficient driving force to evenly distribute Cl- within the extracellular space and that a small re-distribution takes place after strong network activity including inhibitory signaling. In contrast we show a significant difference in regional levels of available extracellular Cl- within our target structure, the hippocampal formation. These findings suggest that the brain might employ mechanisms to counteract diffusion processes and thus create region-specific accumulations of ions - most likely to support needs of supply and demand. In our model, the states of vigilance and consciousness were controlled by application of general anesthesia and by doing so we intentionally offset the balance of excitatory and inhibitory brain signaling mechanisms. Previous research has shown that isoflurane anesthesia induces unconsciousness by modulating thalamocortical neurons. These neurons act as a relay for afferent sensory signals en route to the cortex. Isoflurane hyperpolarizes the cell membrane of these neurons and thus reduces their responsiveness to excitatory synaptic signaling. At the same time it appears that most cortical neurons are not subjected to isoflurane modulation in the same way. On the contrary, we observed diminishing inhibitory responses to afferent stimuli in cortical neurons under increasing levels of isoflurane, especially during conditions producing anesthesia-induced coma. In addition to these micro dynamic mechanisms we also investigated global whole-brain processes pertaining to inhibition. Under conditions of deep anesthesia, we observed two novel phenomena: Firstly, we demonstrated that even during comatose states, subliminal stimulations can elicit brain bursting responses - however only during a certain window during the anesthesia-induced passage from sleep-like behaviors to coma. Therefore, synaptic responses can indeed be elicited even during comatose states. This finding may constitute a vital piece of the puzzle for clinicians working with comatose patients and trying to re-vitalize brain circuits. Secondly, we observed a novel brain activity pattern which emerges under extremely high applications of isoflurane anesthesia – beyond the levels required for induction of a continuously flat (isoelectric) EEG line. This surprising finding demonstrates the importance of the circuit-level balance between excitation and inhibition, as even though the isoelectric line might appear to pose the ultimate dominance of inhibition, some form of excitatory activity can emerge and re-vitalize brain circuits. We conclude that excitation and inhibition might not balance in an all-or-none fashion and that an increase in inhibition does not automatically cause sleep and/or coma. Rather, excitation and inhibition should be understood as very localized processes during which the activity of a few neurons can tip the balance between the states of consciousness.

Les patients admis aux soins intensifs (SI) souffrent de comorbidités qui affectent leur pronostic. Deux problèmes sont potentiellement associés aux sédatifs et compliquent le séjour de 35 à 50% des malades : le délirium, un état confusionnel aigu; et le coma ‘iatrogénique’, une altération de la conscience induite pharmacologiquement. L’importance de l’association entre clinique et médicaments a un intérêt pour prévenir ces syndromes cliniques morbides. Nous voulions étudier le délirium et le coma iatrogénique, les doses administrées de midazolam et de fentanyl, leurs niveaux plasmatiques, les variantes génétiques de métabolisme et de transport et les facteurs inflammatoires et ce, chez 100 patients admis aux soins intensifs. Nos données soulignent l’importance des interactions médicamenteuses dans l’incidence du coma iatrogénique, et réfutent l’association entre les benzodiazépines et le délirium. Ces résultats clarifient la pathophysiologie du délirium, corroborent le manque d’association délirium-benzodiazépines avec un marqueur biologique, c.-à-d. les niveaux sériques, et ouvrent le débat quant aux agents les plus utiles pour traiter l’anxiété et le délirium. Finalement, plusieurs caractéristiques pharmacocinétiques des benzodiazépines administrées aux soins intensifs publiées récemment complètent les données de notre étude quant à la sédation en soins critiques. Un chapitre sur l’importance de la pharmacogénomique en soins intensifs et un débat publié quant au pro et con de l'utilisation des benzodiazépines aux SI, sont soumis en complément de l’étude clinique décrite ci-haut effectuée dans le cadre de cette maîtrise. / Critically ill patients suffer from co-morbid conditions that impact on their prognosis. Two problems complicate Intensive Care Unit (ICU) stay in 35-50% of patients and are potentially associated with sedatives: delirium, an acute confusional state, and 'iatrogenic' coma, when consciousness is altered pharmacologically. Establishing the association between these clinical syndromes and administering sedatives is key in planning effective prevention of these morbid complications. We studied iatrogenic delirium and coma in 100 ICU patients given midazolam and/or fentanyl, and tallied drug doses, measured plasma levels, genetic variations in metabolism and transport and inflammatory factors. Our data highlight the role drug-drug interactions play in iatrogenic coma, and refute the association between benzodiazepines and delirium. These results clarify the pathophysiology of delirium, corroborate the lack of delirium-benzodiazepine association with a benzodiazepine biological marker, i.e. serum levels, and open the debate as to which agents are useful for treating anxiety and delirium. Recent publications addressing benzodiazepine pharmacokinetics in critical care complement our data in the field of critical care sedation. A chapter on the importance of pharmacogenomics in intensive care, and a published pro-con debate as to benzodiazepine use in critical care are submitted in addition to the clinical study mentioned above as part of this master’s thesis.