La durabilité de deux systèmes intégrés d'agriculture et d'aquaculture adoptés dans le delta du Mékong au Vietnam : étude de cas

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Synthétiseur de fréquences RF destiné aux dispositifs médicaux implantables

RÉSUMÉ Les microsystèmes biomédicaux implantables présentent un énorme potentiel pour la recherche médicale. Les dispositifs médicaux intelligents implantables, qui combinent des capteurs et/ou des actuateurs avec des circuits intégrés, ouvrent la voie à des applications fascinantes. Aujourd’hui, la possibilité d’utiliser la technologie CMOS pour intégrer des circuits RF, numériques, et même certains types de capteurs sur une même puce, suscite un vif intérêt dans un domaine nouveau : celui des réseaux de capteurs implantables, ou BSN (Body-Sensor Networks) et leurs applications en recherche biomédicale. L’implantation dans le corps de tels réseaux de capteurs sans-fils permettrait de surveiller, détecter ou même combattre différentes maladies, et ce de manière in situ. Avec des dimensions minimales inférieures à 100 nm, la technologie CMOS représente un choix viable pour l’implémentation des blocs de bases des circuits intégrés radio-fréquences (Radio- Frequency Integrated Circuits - RFIC) à faible consommation de puissance. Toutefois, la réduction de la tension d’alimentation permise dans les procédés CMOS nanométriques, l’impédance de sortie limitée des transistors disponibles, ainsi que les variations de procédés ont pour conséquence que plusieurs architectures de circuits analogiques n’offrent plus les performances requises ou ne sont tout simplement plus applicables. Des méthodes de conception innovatrices doivent être utilisées et des compromis judicieux doivent être faits afin de maintenir les performances requises. Dans un système de communication sans-fil, l’oscillateur local (Local Oscillator - LO) est l’un des modules les plus importants puisqu’il sert à générer la porteuse du lien RF qui sera par la suite modulée pour transmettre les données. Dans un contexte où la consommation de puissance doit être strictement minimisée, la génération d’une fréquence porteuse RF stable dans un procédé CMOS nanométrique présente des défis énormes. Dans cette optique, cette thèse se concentre sur la conception, l’analyse, ainsi que sur l’implémentation de circuits analogiques et RF à basse tension faisant partie d’un synthétiseur de fréquences à consommation ultra faible utilisant un procédé CMOS nanométrique. Tout d’abord, une nouvelle architecture de miroir de courant présentant une impédance de sortie très élevée destiné aux applications à faible tension d’alimentation est présentée. Ce miroir de courant de faible complexité présente une résistance de sortie très élevée et ce pour des tensions de sortie s’approchant des alimentations. Ensuite, une nouvelle architecture de pompe de charges CMOS destinée aux boucles à verrouillage de phase à faible tension et faible puissance est proposée afin de contourner les difficultés causées par la basse tension d’alimentation et la faible impédance de sortie des transistors nanométriques.----------ABSTRACT Implantable biomedical microsystems present a huge potential for medical research. The recent possibility to use CMOS technology to integrate radio-frequency (RF) circuits, baseband signal processing, and even sensors on a same chip has led to a tremendous growth of interest in wireless sensors and their applications. Such microsystems typically include a microprocessor and memory, an energy source, one or more sensors, an analog-to-digital converter (ADC), and a RF transceiver to communicate with a remote base-station or processing unit. In the biomedical field, it is expected that implanting such wireless sensing microsystems could greatly help the medical research community in learning about the progression of some diseases and assess degree of response to treatment. With a minimum feature size that has reduced under 100 nm, CMOS technology has become a viable choice for the implementation of low-power radio-frequency integrated circuits (RFIC) building blocks. However, the reduction of the supply voltage combined with the low output impedance of nanometer transistors have caused many analog and RF circuit solutions to be unsuitable, or even unusable due to voltage headroom constraints. Therefore, new circuit techniques and innovative design approaches are needed in order to meet the required performance level while maintaining low power consumption. In a wireless communications system, the local oscillator (LO) is one of the most important building blocks since it generates the RF carrier signal upon which data is modulated for transmission. In a context where power consumption must be strictly minimized, the generation of a stable RF carrier using a nanometer CMOS process presents huge challenges. In this regard, this thesis focuses on the design, the analysis and the implementation of low-voltage analog and RF circuits used to build an ultra-low power integer-N frequency synthesizer. First, a new current mirror architecture dedicated to low-voltage, low-power applications is presented. The proposed current mirror offers a very high output resistance and an enhanced output voltage range in comparison with other current mirrors similar in architecture. Then, a novel charge pump dedicated to low-power low-voltage PLLs is proposed. The design of this circuit was motivated by the need of a nano-CMOS charge pump that would offer constant current magnitude and minimum current mismatch over a wide range of output voltage, while maintaining power consumption and complexity level as low as possible. A LC resonator-based voltage-controlled oscillator (LC-VCO) that implements a new technique to reduce the impact of process variation on phase noise and power consumption is presented

Analyse géographique de la vulnérabilité de la population associée aux inondations dans trois municipalités québécoises : Châteauguay, Montmagny et Sainte-Brigitte-de-Laval

Dans un contexte d'amplification d'évènements climatiques majeurs, la population fait face à différents impacts négatifs, touchant autant leur bien-être que leur environnement. Ce mémoire de maîtrise consiste à réaliser une analyse géographique de la vulnérabilité de la population québécoise face aux inondations. Une analyse plus approfondie est effectuée sur les municipalités de Châteauguay, Montmagny et Sainte-Brigitte-de-Laval. Jusqu'à ce jour, peu d'indicateurs étaient disponibles pour analyser la vulnérabilité de la population face à cet aléa climatique à l'échelle du Québec. Cette étude permet d'identifier et d'analyser les zones vulnérables aux inondations à l'échelle des municipalités québécoises. Dans le but de cartographier ces phénomènes, la sélection de variables retenues d'après une revue de littérature, la création d'indicateurs synthétiques et d'une cartographie synthétique de la vulnérabilité sont primordiales. La mise en place d'une cartographie participative auprès des acteurs municipaux a été effectuée afin de connaître la situation spécifique des municipalités face aux inondations et de valider les résultats obtenus lors de l'élaboration des indicateurs synthétiques. Cette recherche, autant au niveau méthodologique que cartographique, se base sur deux dimensions de la vulnérabilité, soit la sensibilité et la capacité à faire face. À terme, cette étude a permis de mettre en évidence les zones se retrouvant dans une situation de vulnérabilité à la survenue de cet aléa climatique extrême, correspondant ainsi aux zones sensibles et où la capacité à faire face aux inondations est moindre. Mots-clés : Vulnérabilité, inondation, sensibilité, capacité à faire face, cartographie, municipalités québécoises

Approaches to Global Citizenship

James Tully, University of Virginia, describes two different yet overlapping modes of global citizenship which he calls liberal and democratic global citizenship. More information ... Respondent: Louis-Philippe Hodgson, York University, Dept. of Philosoph

Approaches to Global Citizenship

James Tully, University of Virginia, describes two different yet overlapping modes of global citizenship which he calls liberal and democratic global citizenship. More information ... Respondent: Louis-Philippe Hodgson, York University, Dept. of Philosoph

Les besoins informationnels en gestion de la production dans les PME : une approche autodiagnostique assisté par ordinateur

Operations management in manufacturing SMEs is becoming more complex and demanding (just-in-time, ISO 9000). For managers, this implies increased information needs that only computer-based systems can adequately satisfy. This article presents a prototype computer-based tool for the self-diagnostic of these needs, including the justification of the approach, strategy and method of analysis used, and its experimentation in two enterprises

The ERP correlates of self-knowledge: Are assessments of one’s past, present, and future traits closer to semantic or episodic memory?

Self-knowledge concerns one’s own preferences and personality. It pertains to the self (similar to episodic memory), yet does not concern events. It is factual (like semantic memory), but also idiosyncratic. For these reasons, it is unclear where self-knowledge might fall on a continuum in relation to semantic and episodic memory. In this study, we aimed to compare the event-related potential (ERP) correlates of self-knowledge to those of semantic and episodic memory, using N400 and Late Positive Component (LPC) as proxies for semantic and episodic processing, respectively. We considered an additional factor: time perspective. Temporally distant selves have been suggested to be more semantic compared to the present self, but thinking about one’s past and future selves may also engage episodic memory. Twenty-eight adults answered whether traits (e.g., persistent) were true of most people holding an occupation (e.g. soldiers; semantic memory condition), or true of themselves 5 years ago, in the present, or 5 years from now (past, present, and future self-knowledge conditions). The study ended with an episodic recognition memory task for previously seen traits. Present self-knowledge produced mean LPC amplitudes at posterior parietal sites that fell between semantic and episodic memory. Mean LPC amplitudes for past and future self-knowledge were greater than for semantic memory, and not significantly different from episodic memory. Mean N400 amplitudes for the self-knowledge conditions were smaller than for semantic memory at sagittal sites. However, this N400 effect was not separable from a preceding P200 effect at these same electrode sites. This P200 effect can be interpreted as reflecting the greater emotional salience of self as compared to general knowledge, which may have facilitated semantic processing. Overall, our findings are consistent with a distinction between knowledge of others and self-knowledge, but the closeness of self-knowledge’s neural correlates to either semantic or episodic memory appears to depend to some extent on time perspective

A Missense Mutation (Q279R) in the Fumarylacetoacetate Hydrolase Gene, Responsible for Hereditary Tyrosinemia, Acts as a Splicing Mutation

Background: Tyrosinemia type I, the most severe disease of the tyrosine catabolic pathway is caused by a deficiency in fumarylacetoacetate hydrolase (FAH). A patient showing few of the symptoms associated with the disease, was found to be a compound heterozygote for a splice mutation, IVS6-1g->t, and a putative missense mutation, Q279R. Analysis of FAH expression in liver sections obtained after resection for hepatocellular carcinoma revealed a mosaic pattern of expression. No FAH was found in tumor regions while a healthy region contained enzymeexpressing nodules. Results: Analysis of DNA from a FAH expressing region showed that the expression of the protein was due to correction of the Q279R mutation. RT-PCR was used to assess if Q279R RNA was produced in the liver cells and in fibroblasts from the patient. Normal mRNA was found in the liver region where the mutation had reverted while splicing intermediates were found in nonexpressing regions suggesting that the Q279R mutation acted as a splicing mutation in vivo. Sequence of transcripts showed skipping of exon 8 alone or together with exon 9. Using minigenes in transfection assays, the Q279R mutation was shown to induce skipping of exon 9 when placed in a constitutive splicing environment. Conclusion: These data suggest that the putative missense mutation Q279R in the FAH gene acts as a splicing mutation in vivo. Moreover FAH expression can be partially restored in certain liver cells as a result of a reversion of the Q279R mutation and expansion of the corrected cells

The ERP correlates of self-knowledge in ageing

Self-knowledge is a type of personal semantic knowledge that concerns one’s self-image and personal identity. It has most often been operationalized as the summary of one’s personality traits (“I am a stubborn person”). Interestingly, recent studies have revealed that the neural correlates of self-knowledge can be dissociated from those of general semantic and episodic memory in young adults. However, studies of “dedifferentiation” or loss of distinctiveness of neural representations in ageing suggest that the neural correlates of self-knowledge might be less distinct from those of semantic and episodic memory in older adults. We investigated this question in an event-related potential (ERP) study with 28 young and 26 older adults while they categorised personality traits for their self-relevance (self-knowledge conditions), and their relevance to certain groups of people (general semantic condition). Participants then performed a recognition test for previously seen traits (episodic condition). The amplitude of the late positive component (LPC), associated with episodic recollection processes, differentiated the self-knowledge, general semantic, and episodic conditions in young adults, but not in older adults. However, in older adults, participants with higher composite episodic memory scores had more differentiated LPC amplitudes across experimental conditions. Moreover, consistent with the fact that age-related neural dedifferentiation may be material and region specific, in both age groups some differences between memory types were observed for the N400 component, associated with semantic processing. Taken together, these findings suggest that declarative memory subtypes are less distinct in ageing, but that the amount of differentiation varies with episodic memory function

Multiple Novel Nesprin-1 and Nesprin-2 Variants Act as Versatile Tissue-Specific Intracellular Scaffolds

<div><h3>Background</h3><p>Nesprins (<u>N</u>uclear <u>e</u>nvelope <u>s</u>pectrin-<u>r</u>epeat <u>p</u>roteins) are a novel family of giant spectrin-repeat containing proteins. The nesprin-1 and nesprin-2 genes consist of 146 and 116 exons which encode proteins of ∼1mDa and ∼800 kDa is size respectively when all the exons are utilised in translation. However emerging data suggests that the nesprins have multiple alternative start and termination sites throughout their genes allowing the generation of smaller isoforms.</p> <h3>Results</h3><p>In this study we set out to identify novel alternatively transcribed nesprin variants by screening the EST database and by using RACE analysis to identify cDNA ends. These two methods provided potential hits for alternative start and termination sites that were validated by PCR and DNA sequencing. We show that these alternative sites are not only expressed in a tissue specific manner but by combining different sites together it is possible to create a wide array of nesprin variants. By cloning and expressing small novel nesprin variants into human fibroblasts and U2OS cells we show localization to actin stress-fibres, focal adhesions, microtubules, the nucleolus, nuclear matrix and the nuclear envelope (NE). Furthermore we show that the sub-cellular localization of individual nesprin variants can vary depending on the cell type, suggesting any single nesprin variant may have different functions in different cell types.</p> <h3>Conclusions</h3><p>These studies suggest nesprins act as highly versatile tissue specific intracellular protein scaffolds and identify potential novel functions for nesprins beyond cytoplasmic-nuclear coupling. These alternate functions may also account for the diverse range of disease phenotypes observed when these genes are mutated.</p> </div