The research initiatives addressed in this thesis are geared towards improving the performance of passive optical networks through the development of advanced dynamic bandwidth allocation protocols. In particular, the aim of the research undertaken is to enhance the quality of service offered by standard passive optical networks with reduced network costs. To that extent, a dynamic multi-wavelength protocol has been developed to increase the network upstream bandwidth and introduce multiple service levels to a fibre to the home-based giga-bit passive optical network. Simulation results have confirmed the reduction of the mean packet delay by adjusting the ITU-T standard G984 giga-bit passive optical network frame format by means of the introduction of extended wavelength band overlay based on the ITU-T Coarse- Wavelength Division Multiplexing grid to support the multi-wavelength functionality. To evaluate the multi-wavelength upstream operation of the newly implemented models in OPNET, 2-dimensional Dynamic Bandwidth Allocation algorithms have been introduced to manage the network resources in both the time and wavelength domains. Furthermore, the enhanced traffic allocation among the supported wavelengths in new protocol confirmed a performance improvement in the network total capacity and the mean packet delay, which demonstrates the network reliability and improves the quality of the provided service according to the subscriber service level agreement, with a minimum guaranteed bandwidth of 100 Mbit/s to fulfil applications and associated bandwidth requirements for the next generation access network.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

La sclérose latérale amyotrophique (SLA) est une maladie neurodégénérative fatale de l'âge adulte, caractérisée par une perte de motoneurones, conduisant à une atrophie et une faiblesse musculaires. Des mutations de la superoxyde dismutase-1 (SOD1) provoquent une forme génétique de SLA. Comme chez les patients atteints de SLA, le modèle animal de SLA, SOD1 mutant, révèle que tous les motoneurones sont inégalement sensibles à l'évolution de la maladie. Les mitochondries, centrales énergétiques des cellules, sont des organelles précocement touchées dans la pathologie de la SLA. Un mécanisme attrayant qui sous-tend la susceptibilité différentielle est la nécessité bioénergétique variable de sous-ensembles distincts de motoneurones. Cela implique que dans le système nerveux central, la demande bioénergétique pourrait moduler le seuil pathologique. Même en l'absence de perte bioénergétique, on peut imaginer une situation dans laquelle une contrainte pathologique modifie le niveau à partir duquel la production ou la livraison de l'ATP devient insuffisant, précipitant la chute des neurones les plus vulnérables. Dans les neurones, la majorité de l'ATP est produite par les mitochondries et l'homéostasie des gradients d'ions est le procédé le plus énergivore. La fonction mitochondriale est moindre pour modifier les propriétés électriques des motoneurones si la disponibilité en ATP devient insuffisante pour permettre aux pompes ioniques de maintenir des gradients appropriés. Nous avons démontré que la concentration intracellulaire basale d’ATP dans des cultures de neurones moteurs est diminuée dans les cellules mutées SOD1 par rapport au type sauvage. Paradoxalement à ce résultat, le taux de consommation d'oxygène des mitochondries est augmenté dans les motoneurones SOD1m et il n'existe aucune preuve d'une augmentation de la consommation. Nos résultats appuient l'hypothèse intéressante qu'il y a un découplage entre la chaîne respiratoire et la production d'ATP. Ce découplage peut être utilisé comme une stratégie pour minimiser les propriétés toxiques des mitochondries hyper stimulées. / Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disorder characterized by a loss of motor neurons, leading to muscle wasting and weakness. Mutations in superoxide dismutase-1 (SOD1) cause a form of ALS. As in ALS patients, the mutant SOD1 animal model of ALS reveals that not all motor neurons are equally susceptible to the disease process. An attractive mechanism underlying differential susceptibility is the variable bioenergetics need of distinct subsets of motor neurons. This implies that within the CNS, bioenergetics can modulate the pathological threshold. Even in the absence of loss in bioenergetics, one can envision a situation in which a pathological stress alters the level at which either the production or delivery of ATP becomes insufficient, precipitating the demise of the most vulnerable neuron types. In neurons, majority of ATP is produced by mitochondria and the homeostasis of ion gradients is the most energy-consuming process. Reduced mitochondrial function will modify the electrical properties of motor neurons if ATP availability becomes insufficient to allow ion pumps to maintain appropriate gradients. We demonstrated that the basal ATP intra-cellular concentration in motor neuron cultures lower in SOD1 mutated cells compared to wild type. Paradoxically to this result, the oxygen consumption rate of mitochondria is increase in mSOD1 cells and there is no evidence for an increase of consumption. Our results support the interesting hypothesis that there is an uncoupling between the respiratory chain and the ATP production. This uncoupling might be used as a strategy to minor the toxic properties of hyper stimulated mitochondrion.

De plus en plus d’études suggèrent un rôle important du métabolisme énergétique dans la sclérose latérale amyotrophique (SLA). Ainsi, une intolérance au glucose, une résistance à l’insuline et un hypermétabolisme lipidique sont très souvent retrouvés chez les patients et dans les modèles animaux de SLA. Cependant, les bases cellulaires et moléculaires qui sous-tendent ces altérations restent largement méconnues. Une récente étude menée dans un modèle souris de SLA, indique qu’un dysfonctionnement de la pyruvate déshydrogénase (PDH) induirait, dans les muscles rapides, un déséquilibre des voies cataboliques vers une utilisation privilégiée des lipides, et non plus du glucose. Dans ce contexte, nous avons voulu évaluer dans quelles mesures un programme ciblé d’exercice physique pourrait réorienter les voies métaboliques vers une utilisation privilégiée du glucose dans les souris SOD1(G93A), modèle de SLA. Nous avons comparé les effets de deux types d’entraînement, l’un basé sur un exercice de course de faible intensité, assimilable à un exercice d’endurance, l’autre basé sur un exercice de nage à forte intensité, assimilable à un exercice de force/résistance. Contrairement à la course, l’exercice de nage réduit significativement l’intolérance au glucose, augmente le taux sanguin de lactate et le stockage lipidique dans les adipocytes. Dans le muscle rapide tibialis, touché très précocement par la maladie, nous mettons en évidence une altération de l’expression de GLUT4, transporteur musculaire majeur du glucose, et de la glyceraldehyde-3 phopshate deshydrogenase (GAPDH), une enzyme clé de la glycolyse. Ces altérations moléculaires sont retrouvées dans des biopsies musculaires de patients SLA. L’entraînement à la nage des souris SLA stimule l’expression de GLUT4 et de GAPDH, grâce à la réactivation de processus d’autophagie, et réactive les enzymes du métabolisme aérobie, telles que la citrate synthase, enzyme du cycle de Krebs, et la cytochrome oxydase, appartenant à la chaîne respiratoire mitochondriale. L’ensemble de ces données indique qu’un exercice bien calibré peut améliorer le métabolisme énergétique dans un contexte de SLA, et ouvre la voie à une utilisation de l’exercice physique en complément d’une potentielle modulation pharmacologique de la PDH chez les patients. / The use of physical exercise as an intervention for alleviating symptoms in Amyotrophic-Lateral-Sclerosis (ALS) is debated. We have reported that swimming based exercise sustained motor function, induced a significant neuroprotection and extended SOD1(G93A) ALS mouse lifespan in contrast to running based exercise. Because exercise types are expected to differentially alter, in trained skeletal muscles, the energy metabolism, whose defects have been very recently linked to ALS-induced motor-neuron death, we compared the impact of either a daily swimming- or running-based training on several metabolic indicators in ALS mice. We indicate that, unlike running, the swimming-based training of ALS mice led to a significant increase in lipogenesis and glucose tolerance, and reverse the metabolic switch affecting fast-twitch muscles. Besides, our data highlighted detrimental-side effects of the running-based training that further shifted the energetic status towards a more oxidative metabolism. Thus, the present data outline the paramount importance of the choice of the exercise type when designing rehabilitation protocols for ALS patients.

La sclérose latérale amyotrophique [SLA] est une pathologie idiopathique à issue fatale caractérisée par la dégénérescence progressive et sélective des motoneurones du système nerveux central et périphérique. La SLA n’est pas exclusivement identifiée comme une maladie de la voie pyramidale, mais considérée plus largement comme une pathologie neurodégénérative multisystème. L’étude des mécanismes posturaux dans cette population n’a pas fait l’objet d’une grande attention. Dans ce travail de thèse, une exploration en imagerie cérébrale multimodale (imagerie en tenseur de diffusion [DTI] et morphométrie basée sur le voxel [VBM]) est proposée chez des patients SLA avec instabilité posturale [AIP] et stables [SIP] en vue de vérifier l’intégrité morphologique et structurelle des régions corticales et sous-corticales posturales. La comparaison entre les sujets contrôles et les patients SLA a démontré une augmentation significative du volume de la substance grise au niveau du noyau caudé chez les patients stables (SIP vs contrôle p<0,001 ; SIP vs AIP p<0,01). L’évaluation structurelle a révélé une diminution de la fraction d’anisotropie [FA] au niveau de l’aire motrice supplémentaire [AMS] dans les deux groupes de patients par rapport aux contrôles (contrôle vs SIP p<0,05 ; contrôle vs AIP p<0,001). Au niveau du noyau caudé, le groupe AIP a présenté une diminution de la valeur de la FA par rapport aux sujets contrôles (p<0,001) et aux sujets SIP (p<0,05). Ainsi, ces résultats contribuent à une meilleure caractérisation et compréhension des atteintes corticales et sous corticales des régions qui interviennent dans la posture chez les patients SLA. / The Amyotrophic Lateral Sclerosis [ALS] is an idiopathic pathology with a fatal outcome. It is characterized by a progressive and selective degeneration of motor neurons in the central and peripheral nervous system. ALS is no longer exclusively identified as a disease of the pyramidal pathway, but it is considered more broadly as multisystem neurodegenerative pathology. However, the analysis of postural processes in these patients has not been well studied in the literature. Multimodal brain imaging (Diffusion Tensor Imaging [DTI] and Voxel Based Morphometry [VBM]) exploration was performed for ALS patients with postural instability [AIP] and without postural instability [SIP] to test the morphometric and structural integrity of postural cortical and subcortical regions. A significant increase of gray matter in caudate nucleus volume has been noticed for stable patients (SIP vs controls p<0.001, SIP vs AIP p<0.01). The structural evaluation revealed a decrease of the Fractional Anisotropy [FA] at the Supplementary Motor Area [SMA] level in both groups of patients compared to controls (controls vs SIP p<0.05, controls vs. AIP p<0.001). At the caudate nucleus, the AIP group showed FA value decrease compared to controls (p<0.001) and SIP subjects (p<0.05). Thus, these results would contribute to a better characterization and understanding of the cortical and subcortical impairments of the postural regions in ALS patients.

Geographically, Sweden is significantly closer to England as opposed to America, two English speaking countries with two rather different varieties of the language. With regard to Britain’s history of colonization it could be assumed that British English (RP-variety) would be most frequently used globally. However, America’s power position in politics, economics, international businesses, and movie industries have contributed to making the American English (GA-variety) the more predominantly used variety of the two (Barber, 2000, p. 236). In the different varieties, the vowels /əu/ /ou/ /ju:/ /u:/ /ɑ:/ /æ/ /ɒ/ /ɑ/ /aɪ/ /i:/ and the consonants /ə/ /r/ /t/ /d/ show the most prominent difference in pronounciation (Navrátilová, 2013). Furthermore, Axelsson (2002, p.144) (in Alftberg, 2009, p. 4) claims that with regard to the previously mentioned factors, Swedish students come in contact with several different varieties of English on a daily basis, thus a one-accent-only approach seems outdated for learning purposes. In addition to this, the syllabus for teaching English in Sweden, LGY11 (SNAE, 2011) lays focus, not explicitly on pronunciation, but on intonation and fluency, two factors which are certainly affected by one’s pronunciation and prosody. The document also emphasizes the importance of incorporating different varieties of English from different English speaking cultures and countries into the lessons (SNAE, 2011).This raised the question of whether or not Swedish upper secondary school students tend to follow the global Americanization of pronunciation, if they still adhere to using RP due to its geographical proximity and former prestige, or if they mix different varieties. Therefore, a study was conducted on Swedish students’ pronunciation tendencies and attitudes towards different pronunciations. 58% of the students claimed to use GA and said that TV/YouTube is where they hear English the most. Only 17% claimed they used RP. However, the recordings of the students indicated that the majority used a mixture of the two, and only one student was completely consistent in their variety. Keywords: English pronunciation, Sweden, General American, Received Pronunciation, Teaching, Upper secondary school

The Master's Thesis is generally about facility management -- its essence, individual services it consists of, and also about their integration when they are provided by one key supplier, and finally about their complex integration in one service package, i. e. complex integrated supporting services provision what is a modern trend of this discipline. The aim of the thesis is to evaluate the advantages and efficiency of the trend of service integration under one key supplier based on specific practical examples.

La Sclérose Latérale Amyotrophique (SLA) est une maladie neurodégénérative incurable caractérisée par la perte progressive des motoneurones. Récemment, des mutations dans le gène UBQLN2, codant pour l'ubiquiline 2, ont été identifiées dans des formes héréditaires de SLA et de SLA avec Démence Fronto-Temporale (SLA-DFT). Ces mutations induisent la formation d'agrégats positifs à l'ubiquiline 2 dans la moelle épinière de patients atteints de SLA et dans le cerveau de patients atteints de SLA-DFT, ainsi que dans d'autres formes familiales et dans des formes sporadiques de la maladie. En raison de l'implication de l'ubiquiline 2 dans la dégradation protéique intracellulaire, son rôle semble être déterminant dans la pathogénèse des différents types de SLA. Afin d'étudier les mécanismes physiopathologiques de la maladie et d'envisager des solutions thérapeutiques, nous avons créé un modèle murin de SLA et de SLA-DFT liées à l'UBQLN2 qui récapitule l'ensemble des caractéristiques associées à la maladie, suite à l'injection intracérébroventriculaire de vecteurs viraux associés à l'adénovirus (AAV) de sérotype 10, renfermant l'ADNc muté de l'ubiquiline 2. De plus, nos analyses de spectrométrie de masse ont révélé une perte d'interaction de l'ubiquiline 2 mutée avec une protéine indispensable pour le maintien du cytosquelette des neurones, l'?-spectrine. Enfin, nous avons observé que le Bleu de Méthylène augmente la quantité d'inclusions engendrées par la surexpression de l'ubiquiline 2 mutée. Cette étude a donc permis d'obtenir un paradigme solide pour l'étude de l'implication de l'ubiquiline 2 dans la SLA et pourra servir à l'élaboration de stratégies thérapeutiques efficaces. / Amyotrophic Lateral Sclerosis (ALS) is an incurable neurodegenerative disease characterized by progressive loss of motor neurons (MNs). Recently, mutations in the UBQLN2 gene, encoding ubiquilin 2, have been identified in hereditary forms of ALS and ALS with FrontoTemporal Dementia (ALS-FTD). These mutations induce the formation of ubiquilin-2-positive aggregates in the spinal cord of patients with ALS and in the brain of patients with ALS-FTD, as well as in other familial forms and in sporadic forms of ALS and ALS-FTD. The role of ubiquilin 2 seems to be crucial in the pathogenesis of the different types of ALS, due to its involvement in proteostasis. To understand the physiopathology of the disease and to envision therapeutic strategies, we have generated an ubiquilin 2-linked ALS and ALS-FTD mouse model which recapitulated disease associated phenotypes, after intracerebroventricular (ICV) injection of Adeno Associated Virus serotype rh10 (AAV10) vectors, containing the cDNA encoding mutated ubiquilin 2. Furthermore, mass spectrometry analysis revealed a loss of interaction between the mutant protein and one protein necessary for cytoskeleton maintenance of neurons, the α-spectrin. Finally, we have observed that Methylene Blue increased the number of inclusions in mice expressing the mutant ubiquilin 2. In conclusion, this study presents a solid paradigm to study the involvement of ubiquilin 2 in ALS and can be used for the development of effective therapeutic strategies.

This study investigates the strategies that learners of isiZulu use to understand and make themselves understood when they communicate in computer chatrooms. Chatrooms are viable tools for capturing linguistically rich interactions in conditions that are less restricted than the traditional classroom. The number and types of communication strategies that second language learners attempt, as well as their success in deploying them, have been a topic of interest to researchers in second language acquisition (SLA) because of their apparent role in the acquisition process. Strategies involve the efficient use of language to achieve successful communication in situations where there is some communicative deficiency, either in understanding or in self-expression. Examples of strategies are when learners ask for assistance from their chat partners, or when they check with their partners for confirmation of whether what they said is understood. This study explores differences in the strategies that intermediate learners of isiZulu use when the person they are chatting with is another isiZulu learner, compared to when their chat partner is a native speaker. The study also investigates whether the topic and type of interlocutor have any effect on communication strategy production. Eight learners were given cultural and personal topics to discuss alternately between their peers and native speakers. Given the tenet of the Interaction Hypothesis that language is best learned through interaction (Gass, 1997, 2003; Long, 1983, 1996), which is facilitated by communication strategies, exploring how strategies are utilized is important to the field of SLA as well as to African language pedagogy. The results of this study show no difference in the number, category and type of strategies used when chatting with peers versus native speakers about personal or cultural topics. The highest learners' use of CSs overall was to solve problems of self-expression when they chatted about cultural topics. This finding encourages the integration of culture and technology use in language classrooms. This study contributes to the small research base in technology and SLA for less commonly taught languages and, it is hoped, will promote the use of online chats and other communication technologies in the teaching of these languages.

The aim of this study was to investigate longitudinally how a child learner acquired verbal morpho-syntax in Japanese in a naturalistic second language (L2) context. Specifically the points of emergence for three verbal morpho-syntactic structures, namely verbal inflection, the V-te V structure and the passive/causative structure, were investigated within a framework of Processability Theory (PT) (Pienemann, 1998b). The subsequent development of these structures was also examined. Unlike earlier research about morpheme orders and developmental sequences in language acquisition which was criticised because of its apparent lack of theoretical underpinnings, Pienemann's Processability Theory (PT)(1998b) connects the processability of morpho-syntactic structure to linguistic theories. Pienemann also claims that this theory can be used to explain the acquisition of a wide range of morpho-syntactic structures and that it is typologically plausible and applicable to any language. In recent times PT has been extensively tested in a range of languages acquired as an L2, including German, English and Swedish (Pienemann, 1998b; Pienemann & Hakansson, 1999) and Italian and Japanese (Di Biase & Kawaguchi, 2002). The findings from these studies support this theory.