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Cette recherche porte sur les caractéristiques familiales associées à l'initiation précoce à la consommation de psychotropes chez les enfants âgés de 10, 11 et 12 ans. Cette étude s'appuie sur le constat suivant : bien que la plupart des individus s'initient à la consommation de psychotropes au cours de l'adolescence ou au début de l'âge adulte, un certain nombre d'entre eux en consommeront dès l'enfance (Oxford, Harachi, Catalano et Abbott, 2000). Aussi, on note que depuis le début des années 1990, les jeunes manifesteraient de moins en moins leur désapprobation à l'égard de la consommation de psychotropes, augmentant ainsi le niveau d'inquiétude face à cette situation (Johnston, O'Malley et Bachman, 1999). Il est reconnu que les enfants qui s'initient à la consommation de psychotropes, tels que le tabac, l'alcool et la marijuana, avant l'âge de 12 ans augmentent singulièrement leurs risques de développer des problèmes de consommation (abus, dépendance) à l'adolescence et à l'âge adulte (Kuperman, Chan, Kramer, Bierut, Bucholz, Fox, Hesselbrock et al. , 2005; Lambert, 2005), et de présenter différents problèmes d'adaptation sur les plans personnel, familial et social (Kuperman et al. , 2005). II semble donc important de s'intéresser à cette problématique, d'autant plus que la période de développement prépubertaire est reconnue fondamentale, notamment sur le plan du développement social, émotionnel, physique, comportemental, cognitif et affectif (Thomassin, 2004). Afin d'intervenir en amont de ces difficultés et d'offrir des programmes de prévention adaptés aux enfants s'étant initiés précocement aux psychotropes, il s'avère essentiel de mieux connaître les caractéristiques familiales associées à ce phénomène (Gouvernement du Québec, 2001). Cela se justifie par le fait qu'il appartient au système familial d'exercer une influence positive afin que l'enfant adopte des comportements adaptés (Clark, Cornelius, Kirisci, et Tarter, 2005; Sung, Erkanli, Angold, et Costello, 2003; Thomassin, 2004). On retrouve effectivement différentes caractéristiques familiales qui seraient associées à l'initiation précoce des enfants à la consommation de psychotropes, notamment, la structure familiale (Saint-Jacques, Turcotte, Drapeau, Cloutier et Doré, 2004), les caractéristiques personnelles des parents dont la présence d'un problème avec la justice, de santé mentale ou de consommation de psychotropes, les pratiques éducatives lacunaires des parents à l'égard des enfants, ainsi qu'un faible engagement parental (Vitaro, Carbonneau, Gosselin, Tremblay et Zoccolillo, 2000). Les objectifs de l'étude sont donc : (1) d'identifier les caractéristiques familiales associées à l'initiation précoce à la consommation de psychotropes chez ces enfants et (2) d'identifier, parmi ces caractéristiques familiales, celles qui sont les plus fortement associées à une initiation précoce aux psychotropes."--Résumé abrégé par UMI.

Many research studies have investigated the role of the principal in implementing change. Despite the information gleaned from those investigations, principals continue to struggle with initiating, implementing, and sustaining change in their schools. Guiding this narrative inquiry study were theories related to principal leadership, educational change theory, and the theories associated with school culture, with the intent to understand the experiences of principals as they initiated, implemented, and sustained change in their schools. This study explored the challenges and successes principals experienced along with the specific actions that contributed to successful implementation. Five principals from southern Idaho were interviewed. Narratives were co-constructed based on each of the principal's experiences. Polyvocal analysis was used to analyze the data and co-construct the narratives with the participants. Common themes were examined and compared to recent research related to principals implementing change. A cross narrative analysis was used to compare the common themes and actions attributed to the successful implementation of change. Analysis of the data revealed that, among these 5 principals, successful implementation of change was created by obtaining buy-in from staff, building trust, distributing leadership, providing structured time for teachers to learn and collaborate, building capacity through targeted professional development, and seeking input from all stakeholders. These findings will promote social change by helping principals to understand the experiences of other principals with initiating, implementing, and sustaining change. Also, the common themes identified will inform principals on how to successfully implement change that will positively affect students.

L’enjeu de la thèse peut-être situé à partir du domaine qu’on appelle aujourd’hui « pédagogie universitaire ». Dans ce domaine, une préoccupation majeure tient aux difficultés que rencontrent beaucoup d’étudiants, notamment au début des études supérieures. Ainsi, au sein d’une littérature désormais abondante, des recherches s’intéressent à l’origine sociale et au passé scolaire des étudiants, d’autres examinent leur attitude face aux études ou bien leurs stratégies d’apprentissage ou encore les dispositifs didactiques mis en place par les enseignants, etc. L’originalité de ce travail est d’entrer dans ce problème en s’interrogeant sur la nature des savoirs enseignés. Le « savoir enseigné » se révèle d’emblée un objet difficile à cerner et même insaisissable : s’agit-il des paroles de l’enseignant, des supports écrits divers auxquels il confronte les étudiants ? Faut-il y inclure ce que les étudiants doivent accomplir par eux-mêmes ? Comment rendre compte de ce qu’il est ? Ce problème conduit à affirmer qu’on ne peut identifier ni même simplement décrire un savoir sans référence à des pratiques. Il s’ensuit une analyse fine et rigoureuse de cette notion de pratique. Si cette notion doit beaucoup aux travaux que Latour et Stengers ont conduits à propos des savoirs et pratiques scientifiques, elle est reconstruite au regard de la spécificité de la pratique enseignante et permet notamment de décrire le processus de réappropriation que la pratique enseignante opère sur des objets et des savoirs qui lui viennent d’autres pratiques. Dès lors, ce que nous appelons couramment « savoir » n’est pas un objet qui aurait une existence propre et indépendante, mais il est toujours pris dans une pratique comme ce qui constitue une réponse pertinente aux contraintes dont elle est constituée. Ainsi le savoir enseigné est le produit d’une construction au sein de la pratique enseignante. On ne peut le concevoir comme un objet qui serait le résultat d’une transmission ou d’un appauvrissement par rapport à un autre objet qui lui préexisterait et qui serait le « savoir savant ». Ces analyses ont un certain nombre d’implications : elles conduisent inévitablement à une ré-interrogation de la notion de transposition didactique. Elles remettent en cause la vieille, mais tenace dichotomie entre théorie et pratique. Elles obligent à penser le savoir comme ce qui s’inscrit dans une pratique et qui est porteur d’enjeux pour ses acteurs. Pour appuyer ces considérations, la thèse contient le compte-rendu de l’observation de l’intégralité de huit cours d’enseignement supérieur (pris à l’université, dans l’enseignement supérieur court et dans la formation continue). Il s’agit, dans cette partie empirique, de mettre à l’épreuve les concepts construits et de voir, sur un ensemble d’unités d’enseignement suffisamment ouverts, s’ils sont assez précis pour rendre compte à chaque fois de la spécificité de la pratique enseignante et du savoir enseigné. Ces huit études de cas conduisent à poser un problème didactique fondamental : sachant que l’étudiant ne peut porter intérêt à un cours que s’il fait l’expérience des enjeux auxquels le savoir enseigné peut répondre, comment lui faire partager ces enjeux ? Cette question conduit à un examen critique de la notion de « situation-problème » et à une ouverture des formes possibles de problématisation, mais également à proposer le concept de « dramatisation » pour désigner les infinies manières de faire partager aux étudiants les enjeux d’un savoir. Il s’ensuit qu’on ne saurait concevoir de méthode pédagogique ou didactique qui pourrait « s’appliquer » indifféremment à n’importe quel contenu de savoir, puisqu’à la fois la dramatisation d’un savoir ne peut s’envisager indépendamment de ce qu’il est ni indépendamment des pratiques de l’enseignant, et qu’en retour il ne saurait y avoir de savoir enseigné qui préexisterait à la pratique d’enseignement.

The length of the primary root and the density of lateral roots determine the architecture of the root. In this thesis the effect of NAA, ABA and the NO donor SNP alone as well as the combination of ABA or NAA with SNP on lateral root development was investigated. The interaction between CPTIO, a NO scavenger, and NAA or SNP is also reported. Following preliminary experiments in which it was observed that the aerial part of the seedling influenced LR growth and that there was a possible inhibitory effect of light on cultured root tips, experiments were conducted with excised roots tips in the dark. NAA was shown to have the potential to initiate LRs across a wide concentration gradient with the total number of LRs and initiated lateral root primordia (LRP) remaining constant across the range of concentrations tested. Over the last decade, nitric oxide (NO), a bioactive molecule, has been reported to be involved in the regulation of many biological pathways. The presence of NO in the system provided via sodium nitroprusside (SNP), promoted LRP initiation based on the NAA concentration gradient; but without changing the total LR initiation, that is LRs plus primordia density remained constant along the concentration gradient of NAA. The absence of LR and LRP in the treatments of CPTIO (a NO scavenger) with SNP or NAA suggests that NO regulates LRP initiation triggered by NAA, which is in agreement with the recent paper published after the commencement of this study (Correa-Aragunde et al., 2006). In agreement with previous studies, ABA inhibited lateral root development by reducing LR density and the number of LRs. The experiments with fluridone, an ABA biosynthesis inhibitor, may indicate that endogenous ABA was at sufficient concentrations in the excised root tips to inhibit primordia initiation. In this study, evidence is presented for the first time to show that SNP can relieve the inhibitory effect of ABA on LR density and number of LRs suggesting the NO, released from SNP, acts downstream of ABA. Overall these data confirm a critical role for NO in LR initiation.

Mechanisms involved in the establishment of HCMV latency are poorly understood, however, work in our laboratory has demonstrated the ULb' encoded protein, pUL138, as the first viral determinant to function in the establishment of HCMV latency in CD34+ hematopoietic progenitor cells (HPCs). This work characterizes the transcripts that encode pUL138, identifies three novel ULb' proteins (pUL133, pUL135, and pUL136) and represents the first demonstration of an internal ribosome entry site (IRES) mediated expression of pUL138. pUL138 is encoded on three polycistronic transcripts of 3.6-, 2.7- and 1.4-kb in length. pUL133, pUL135 and truncated pUL136, are expressed on the 3.6-, 2.7- and 1.4-kb transcripts, respectively, in addition to pUL138. We demonstrate that pUL138 expression is inducible from the IRES on the 3.6- and 2.7-kb transcripts under conditions of cellular stress, whereas pUL138 expression from the 1.4-kb transcript is inhibited under these same conditions. Differential utilization of the UL138 transcripts and their respective encoded proteins may regulate the outcome of viral infection in a cell type or cell context dependent manner. The interaction of these proteins during HCMV latency is the focus of ongoing research. In addition, this work represents preliminary data regarding the type I interferon (IFN) response during HCMV during productive infection in MRC5 fibroblasts and during the establishment of HCMV latency in CD34+ HPCs.

No description available.

This thesis used female genital mutilation as a lens through which the effectiveness of the current laws aimed at protecting women and girls can be explored.

Calcium is a highly versatile intracellular signal molecule that can regulate numerous different cellular functions. In filamentous fungi there is evidence for it being involved in regulating various processes, including spore germination, hyphal tip growth, hyphal branching and conidiation. During colony initiation in the filamentous fungus Neurospora crassa, conidia form germ tubes which are involved in colony establishment, and conidial anastomosis tubes (CATs) which are involved in generating fused networks of conidial germlings. The primary research aim of this thesis was to analyze the role of Ca2+-signalling and homeostasis during colony initiation in N. crassa. Removal of Ca2+ from the growth medium showed that external Ca2+ was necessary for CAT fusion and, more specifically, was required for CAT chemoattraction. Two L-type Ca2+ channel blockers (verapamil and diltiazem) with different modes of action were found to inhibit both conidial germination and CAT fusion in wild type strains and CAT fusion was shown to be more sensitive to these two drugs. These channel blockers were additionally found to inhibit Ca2+ uptake by conidial germlings of the wild type expressing the aequorin Ca2+ reporter. However, the channel blockers also, unexpectedly, raised the cytosolic free Ca2+ ([Ca2+]c) resting level in these germlings suggesting that they did not just inhibit L-type Ca2+ activity. The morphological phenotypes (conidial germination, hyphal extension rate, conidiation and hyphal branching) of 22 mutants defective in different components of their Ca2+-signalling and homeostasis machinery were characterized in order to identify their possible roles of Ca2+ during colony initiation and development. The ∆cch-1 mutant lacking the CCH-1 L-type Ca2+ channel gene exhibited a reduction in CAT fusion. CAT fusion was decreased even further in a double mutant (∆cch-1∆mid-1) suggesting that that the CCH-1 and MID-1 proteins operate in combination during this process. Increased extracellular Ca2+ partially restored the phenotypes of the ∆cch-1, ∆mid-1 smco-1 and ∆cch-1∆mid-1 mutants which is consistent with CCH-1 and MID-1 being involved in Ca2+ uptake from the external medium. Calcium signatures following mechanical perturbation were successfully measured in populations of conidial germlings using aequorin expressed in the wild type and in deletion mutants (∆cch-1, ∆yvc-1, ∆fig-1) lacking different Ca2+ channels. The removal of external Ca2+ completely abolished the [Ca2+]c increase in response to mechanical perturbation and CCH-1 was found to partly contribute to this increase in [Ca2+]c. Various Ca2+-sensitive dyes (Oregon green 488, Fluo-4 and Calcium Green-1) were also tested to determine if they can be used to image [Ca2+]c at the single cell and subcellular levels. Only Fluo-4 allowed the measurement of [Ca2+]c in individual cells but the changes in dye fluorescence in response to changes in [Ca2+]c were too small to be useful for imaging [Ca2+]c dynamics at the subcellular level. The other two dyes underwent rapid compartmentalization in organelles when loaded into germlings. The plant antifungal proteins (defensins), MsDef1, MtDef4 and PAF were all found to disrupt Ca2+ signaling/homeostasis in conidial germlings of N. crassa. They all inhibited the [Ca2+]c increase and raised the resting level of [Ca2+]c in response to mechanical perturbation. Analysis of an aequorin expressing mutant that was defective in glucosylceramide synthase (∆gcs) showed that the effects of MsDef1 (but not MtDef4) on [Ca2+]c were mediated by the sphingolipid glucosylceramide. All of the defensins tested were found to exhibit different potencies with regard to their inhibitory effects on conidial germination and CAT fusion.

This thesis is a narrative inquiry of 10 international students from Nigeria studying in selected UK universities. The thesis draws from emerging discourse on international student’s overseas experiences and extends this knowledge by analysing these experiences from the framework of trauma, individuation, spiritual emergency and the African initiation process, in an attempt to gain an in depth knowledge of Nigerian students’ experiences of studying abroad in the current period. The previous understanding of international students’ experiences from culture shock framework does not account for how their difficult experiences affect their psychological, emotional, physical, social and spiritual wellbeing, so this thesis have reconceptualised these problems and explained them in more depth using the trauma framework and contributed to knowledge in this area. It is an exploratory qualitative study and data for the study was gathered through narrative interviewing. The narrative or story telling method applied in this study enabled the researcher to capture how the participants construct meaning to their lived experiences. The narrative inquiry is chosen because it gives voice to silenced group of people like the Nigerian students whose experiences are not heard. Narratives gathered were textually analysed to evidence the narrators’ unique individual experiences. Findings revealed that the participants had experiences that coincided with trauma experiences such as feeling of helplessness, disorganization, confusion, depression, sleeplessness and disorientation, lack of concentration and supressed emotion as they lived and studied in UK. The thesis concluded from the findings of the study that there is resemblance of trauma experiences in the participants’ stories. The study recommends that support was necessary when they are in UK, while adequate information should be provided before the students sojourn to the UK since most of their difficulties were as a result of failed expectations from their preconceptions about studying in the UK before they arrived.