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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
181

Quantification du mouvement vertical de la croûte terrestre et de sa contribution au changement du niveau de la mer : le cas de la Côte Est du Canada, golfe du Saint-Laurent

Feizabadi, Mohsen 12 1900 (has links)
Les changements du niveau de la mer sont un des indicateurs des changements climatiques qui affectent le monde depuis les dernière décennies. Dans les zones côtières, ce phénomène est à l'origine de l'érosion côtière, l'intrusion d'eau salée dans la nappe phréatique et les inondations. Les côtes du Canada ne sont pas épargnées. En effet, le niveau de la mer dans ces régions augmente actuellement et suit les tendances mondiales. Parmi ces zones côtières, celles du golfe du Saint-Laurent nous ont intéressées. Elles sont caractérisées par des propriétés physiques spécifiques comme l'isolement relatif par rapport l'océan Atlantique, la couverture de glace en hiver et la coulée de l'eau douce au printemps qui leurs confèrent un comportement particulier en termes de changements du niveau de la mer. Les changements du niveau de la mer peuvent être déterminés en intégrant les données des marégraphes et de l'altimétrie satellitaire que le résultat de cette procédure conduit à une détermination relative du niveau moyen de la mer. Cependant, parce que la structure de mesure de ces données est différente, certaines corrections doivent être appliquées. L'une des corrections parmi les plus essentielles est la longueur du Mouvement de Terrain Vertical (MTV) qui doit être prise en compte dans les données des marégraphes, car ces derniers sont connectés directement à la croûte terrestre. Différents phénomènes peuvent causer le MTV. À une échelle locale, la tectonique, l'affaissement et la sédimentation sont les facteurs qui créent le mouvement vertical et à une méso ou macro-échelle, la fonte des inlandsis qui entraîne une modification de la charge de masse de la surface de la terre, provoquent le mouvement des terres. Il existe divers modèles et méthodes de correction du MTV globaux et locaux, tels que l'Ajustement Isostatique Glaciaire (AIG), le Système Mondial de Navigation par Satellite (SMNS), l'Interférométrie par Radar Synthèse d'Ouverture (InRSO), Gravity Recovery and Climate Experiment (GRACE) et le calcul de la différence entre données marégraphiques et altimétriques par satellite. Parmi ces méthodes, l'utilisation de la vitesse verticale des données GPS est la plus précise. Cependant, en raison du faible nombre de stations GPS dans ou proximité des stations marégraphiques, l'utilisation d'une approche plus globale est inévitable. En utilisant cette correction, le niveau moyen absolu de la mer sera obtenu. Dans cette étude, l'évaluation du MTV se fait par un algorithme d'InRSO, appelé Diffuseurs Persistants InRSO (DPInRSO en anglais PSInSAR). Les images du RSO du satellite Sentinel-1 sont soumises à l'analyse DPInRSO. Afin d'évaluer la précision de cette approche, les résultats de DPInRSO (obtenus du logiciel Stanford Method for Persistent Scatterers (StaMPS)) pour deux régions de l'est du Canada (Halifax et St. John's) sont comparés à la GPS vitesse verticale en analysant les séries temporelles de données. Également, en utilisant la même méthode, le mouvement vertical des terres dans 24 stations marégraphiques du golfe du Saint-Laurent sera corrigé. L'étude du niveau moyen de la mer est mise en oeuvre en utilisant l'analyse spectrale (analyse harmonique et analyse spectrale des moindres carrés (ASMC)) afin de supprimer les effets à long terme des constituants de la marée (constituants annuels et semi-annuels). Aussi, pour évaluer le niveau moyen absolu de la mer (NMAM) dans la région considérée, le niveau moyen de la mer calculé est corrigé sur la base des résultats du MTV. En conclusion, la comparaison des résultats de la technique DPInRSO avec les données GPS indique le comportement similaire des tendances au cours de la période d'étude. En d'autres termes, la méthode DPInRSO mesure le mouvement vertical des terres en précision millimétrique dans la région d'étude (à l'exception d'une station) et elle peut être appliquée pour les régions qu'elles ne se connectent pas sur le positionnement GPS continu des marégraphes. Dans le cas d'un changement du niveau de la mer, l'incompatibilité entre les données marégraphiques et altimétriques en termes de temps rend la conclusion plus diffcile. Cependant, sur la base d'observations continues dans des séries temporelles de données altimétriques, nous avons obtenu une tendance plus homogène du niveau de la mer (niveau moyen de la mer) dans toutes les stations, mais pour évaluer le changement à long terme du niveau de la mer et en raison de l'emplacement exact de la station marégraphique, ces dernières données doivent être prises en compte (à la fois dans le calcul du niveau moyen de la mer et des constituants de la marée). Enfin, en raison du faible changement de MTV, les valeurs moyennes absolues du niveau de la mer sont très proches de celles relatives, ce qui indique que nous pouvons évaluer les changements du niveau de la mer dans le golfe du Saint-Laurent, en utilisant uniquement les données marégraphiques et altimétriques. En plus de faire des corrections, des cartes de la tendance du niveau de la mer et des différences de phase entre les stations marégraphiques seront représentées. La qualité des données des marégraphes et de l'altimétrie satellitaire sera discutée et rapportée sur les résultats tirés de l'étude. / Sea level changes are one of the indicators of climate change that has affected the world in recent decades. In coastal areas, this phenomenon has caused coastal erosion, saltwater intrusion into the groundwater and floods. These environmental changes can also be seen in Canada's coasts. Indeed, the sea level in these regions is currently increasing and follows the global trends. Among these coastal areas, those of the Gulf of St. Lawrence interested us. This area is characterized by specific physical properties such as relative isolation from the Atlantic Ocean, winter ice cover and spring freshwater flow that confer particular behavior in terms of sea level changes. Sea level changes can be determined by integrating the tide gauge and satellite altimetry data that the result of this procedure leads to a relative determination of mean sea level. However, because the measurement structures of these data are different, some corrections should be applied. One of the most essential corrections is the length of the Vertical Land Motion (VLM) which must be taken into account in tide gauge data, as these are connected directly to the Earth crust. Different phenomena can cause VLM. In the local scale, tectonics, subsidence and sedimentation are the factors that create vertical movement and in global scale, melting of ice sheets, which leads to change the mass loading of the earth's surface, cause the land motion. There are various global and local VLM correction models and methods such as, Glacial Isostatic Adjustment (GIA), Global Navigation Satellite Systems (GNSS), Interferometry Synthetic Aperture Radar (InSAR), Gravity Recovery and Climate Experiment (GRACE) and calculation of difference between satellite altimetry and tide gauge data. Between these methods, using the vertical velocity of GPS data is the most accurate one. However, due to the low number of GPS stations in or near the tide gauge stations, using a more comprehensive approach is inevitable. By applying this correction, the absolute mean sea level will be obtained. In this study, VLM is examined by one algorithm of InSAR which is called Persistent Scatterer InSAR (PSInSAR). The Sentinel-1 single-look SAR images are used for PSInSAR analysis. In order to accuracy assessment of this approach, the results of PSInSAR (obtained from Stanford Method for Persistent Scatterers software (StaMPS)) for two regions in east of Canada (Halifax and St. John's) are compared with GPS vertical velocity by analyzing their time series data. Equally, by using the same method, vertical land movement in 24 tide gauge station in Gulf of St. Lawrence will be corrected. Investigation of mean sea level is implemented by using the spectral analysis (Harmonic analysis and Least Square Spectral Analysis) in order to remove the long-term effects of tidal constituent (annual and semiannual constituents). Also, to assess the Absolute Mean Sea Level (AMSL) in considered region, calculated mean sea level is corrected based on the results of VLM. In conclusion, comparing of the results of PSInSAR technique with GPS data indicate the similar behavior of trends during the period of study. In other words, PSInSAR method measures vertical land motion in millimeter precision in study region (except of one station) and it can be applied for regions that they do not connect on continuous GPS positioning of tide gauges. In the case of sea level change, incompatibility between tide gauge and altimetry data in terms of time makes the conclusion harder. However, based on continues observations in time series of altimetry data, we obtained more homogeneous sea level trend (mean sea level) in all stations, but to evaluate the long-term sea level change and because of exact location of tide gauge station, this latter data must be considered (both in calculation of mean sea level and tidal constituents). Finally, because of small values of VLM, absolute mean sea level values are very close to relative one which indicate that, we can evaluate the sea level changes in Gulf of Saint Lawrence by using only the tide gauge and altimetry data. In addition to making corrections, the maps of sea level trend and phase differences between tide gauge stations will be represented. The quality of the tide gauge and satellite altimetry records will be discussed and reported over the drawn results of the study.
182

Applications and challenges in mass spectrometry-based untargeted metabolomics

Jones, Christina Michele 27 May 2016 (has links)
Metabolomics is the methodical scientific study of biochemical processes associated with the metabolome—which comprises the entire collection of metabolites in any biological entity. Metabolome changes occur as a result of modifications in the genome and proteome, and are, therefore, directly related to cellular phenotype. Thus, metabolomic analysis is capable of providing a snapshot of cellular physiology. Untargeted metabolomics is an impartial, all-inclusive approach for detecting as many metabolites as possible without a priori knowledge of their identity. Hence, it is a valuable exploratory tool capable of providing extensive chemical information for discovery and hypothesis-generation regarding biochemical processes. A history of metabolomics and advances in the field corresponding to improved analytical technologies are described in Chapter 1 of this dissertation. Additionally, Chapter 1 introduces the analytical workflows involved in untargeted metabolomics research to provide a foundation for Chapters 2 – 5. Part I of this dissertation which encompasses Chapters 2 – 3 describes the utilization of mass spectrometry (MS)-based untargeted metabolomic analysis to acquire new insight into cancer detection. There is a knowledge deficit regarding the biochemical processes of the origin and proliferative molecular mechanisms of many types of cancer which has also led to a shortage of sensitive and specific biomarkers. Chapter 2 describes the development of an in vitro diagnostic multivariate index assay (IVDMIA) for prostate cancer (PCa) prediction based on ultra performance liquid chromatography-mass spectrometry (UPLC-MS) metabolic profiling of blood serum samples from 64 PCa patients and 50 healthy individuals. A panel of 40 metabolic spectral features was found to be differential with 92.1% sensitivity, 94.3% specificity, and 93.0% accuracy. The performance of the IVDMIA was higher than the prevalent prostate-specific antigen blood test, thus, highlighting that a combination of multiple discriminant features yields higher predictive power for PCa detection than the univariate analysis of a single marker. Chapter 3 describes two approaches that were taken to investigate metabolic patterns for early detection of ovarian cancer (OC). First, Dicer-Pten double knockout (DKO) mice that phenocopy many of the features of metastatic high-grade serous carcinoma (HGSC) observed in women were studied. Using UPLC-MS, serum samples from 14 early-stage tumor DKO mice and 11 controls were analyzed. Iterative multivariate classification selected 18 metabolites that, when considered as a panel, yielded 100% accuracy, sensitivity, and specificity for early-stage HGSC detection. In the second approach, serum metabolic phenotypes of an early-stage OC pilot patient cohort were characterized. Serum samples were collected from 24 early-stage OC patients and 40 healthy women, and subsequently analyzed using UPLC-MS. Multivariate statistical analysis employing support vector machine learning methods and recursive feature elimination selected a panel of metabolites that differentiated between age-matched samples with 100% cross-validated accuracy, sensitivity, and specificity. This small pilot study demonstrated that metabolic phenotypes may be useful for detecting early-stage OC and, thus, supports conducting larger, more comprehensive studies. Many challenges exist in the field of untargeted metabolomics. Part II of this dissertation which encompasses Chapters 4 – 5 focuses on two specific challenges. While metabolomic data may be used to generate hypothesis concerning biological processes, determining causal relationships within metabolic networks with only metabolomic data is impractical. Proteins play major roles in these networks; therefore, pairing metabolomic information with that acquired from proteomics gives a more comprehensive snapshot of perturbations to metabolic pathways. Chapter 4 describes the integration of MS- and NMR-based metabolomics with proteomics analyses to investigate the role of chemically mediated ecological interactions between Karenia brevis and two diatom competitors, Asterionellopsis glacialis and Thalassiosira pseudonana. This integrated systems biology approach showed that K. brevis allelopathy distinctively perturbed the metabolisms of these two competitors. A. glacialis had a more robust metabolic response to K. brevis allelopathy which may be a result of its repeated exposure to K. brevis blooms in the Gulf of Mexico. However, K. brevis allelopathy disrupted energy metabolism and obstructed cellular protection mechanisms including altering cell membrane components, inhibiting osmoregulation, and increasing oxidative stress in T. pseudonana. This work represents the first instance of metabolites and proteins measured simultaneously to understand the effects of allelopathy or in fact any form of competition. Chromatography is traditionally coupled to MS for untargeted metabolomics studies. While coupling chromatography to MS greatly enhances metabolome analysis due to the orthogonality of the techniques, the lengthy analysis times pose challenges for large metabolomics studies. Consequently, there is still a need for developing higher throughput MS approaches. A rapid metabolic fingerprinting method that utilizes a new transmission mode direct analysis in real time (TM-DART) ambient sampling technique is presented in Chapter 5. The optimization of TM-DART parameters directly affecting metabolite desorption and ionization, such as sample position and ionizing gas desorption temperature, was critical in achieving high sensitivity and detecting a broad mass range of metabolites. In terms of reproducibility, TM-DART compared favorably with traditional probe mode DART analysis, with coefficients of variation as low as 16%. TM-DART MS proved to be a powerful analytical technique for rapid metabolome analysis of human blood sera and was adapted for exhaled breath condensate (EBC) analysis. To determine the feasibility of utilizing TM-DART for metabolomics investigations, TM-DART was interfaced with traveling wave ion mobility spectrometry (TWIMS) time-of-flight (TOF) MS for the analysis of EBC samples from cystic fibrosis patients and healthy controls. TM-DART-TWIMS-TOF MS was able to successfully detect cystic fibrosis in this small sample cohort, thereby, demonstrating it can be employed for probing metabolome changes. Finally, in Chapter 6, a perspective on the presented work is provided along with goals on which future studies may focus.
183

L'extension artificielle des côtes vers le large et ses conséquences en droit international

Thang, Nguyen Toan 05 December 2005 (has links)
La thèse aborde une question originale et d'actualité: l'extension artificielle des côtes. Afin de mieux comprendre ce phénomène dans son actualité, la thèse attache une importance à la description de la pratique des États en fournissant les informations aussi précises, aussi actuelles et aussi concrètes que possible. C'est à partir de cette pratique que la thèse répond à la question de savoir comment les règles de droit répondent aux exigences de la pratique.<p><p>En ce qui concerne la pratique des États, la thèse explique, dans une première partie, que l'extension artificielle des côtes est destinée, tantôt, à protéger les côtes contre l'élévation du niveau de la mer, tantôt à gagner des terres pour diverses fins: habitat humain, agricoles, développement des ports et de leurs infrastructures pour les besoins des navires modernes et du commerce international. Mais parallèlement, cette extension entraîne des effets négatifs pour l'écosystème côtier (chapitre I). Des travaux de ce genre ont été menés, ou vont l'être, en Europe (Pays-Bas, Allemagne, Belgique, France, R.-U. etc), aux États-Unis, en Asie (Bahreïn, Malaisie, Hong Kong, Singapour, Japon), en Australie, et sur certains archipels du Pacifique (chapitre II).<p><p>La seconde partie de la thèse examine le droit applicable au phénomène d'extension artificielle des côtes. Sont ainsi passées en revue: les règles relatives à la navigation (chapitre III), les règles relatives aux lignes de base (chapitre IV), les règles relatives aux hauts-fonds découvrants (chapitre V), les règles relatives aux îles et aux rochers (chapitre VI) et enfin les règles relatives à la protection de l'environnement marin (chapitre VII).<p> / Doctorat en droit / info:eu-repo/semantics/nonPublished
184

From the "rising tide" to solidarity: disrupting dominant crisis discourses in dementia social policy in neoliberal times

MacLeod, Suzanne 26 March 2014 (has links)
As a social worker practising in long-term residential care for people living with dementia, I am alarmed by discourses in the media and health policy that construct persons living with dementia and their health care needs as a threatening “rising tide” or crisis. I am particularly concerned about the material effects such dominant discourses, and the values they uphold, might have on the collective provision of care and support for our elderly citizens in the present neoliberal economic and political context of health care. To better understand how dominant discourses about dementia work at this time when Canada’s population is aging and the number of persons living with dementia is anticipated to increase, I have rooted my thesis in poststructural methodology. My research method is a discourse analysis, which draws on Foucault’s archaeological and genealogical concepts, to examine two contemporary health policy documents related to dementia care – one national and one provincial. I also incorporate some poetic representation – or found poetry – to write up my findings. While deconstructing and disrupting taken for granted dominant crisis discourses on dementia in health policy, my research also makes space for alternative constructions to support discursive and health policy possibilities in solidarity with persons living with dementia so that they may thrive. / Graduate / 0452 / 0680 / 0351 / macsuz@shaw.ca
185

From the "rising tide" to solidarity: disrupting dominant crisis discourses in dementia social policy in neoliberal times

MacLeod, Suzanne 26 March 2014 (has links)
As a social worker practising in long-term residential care for people living with dementia, I am alarmed by discourses in the media and health policy that construct persons living with dementia and their health care needs as a threatening “rising tide” or crisis. I am particularly concerned about the material effects such dominant discourses, and the values they uphold, might have on the collective provision of care and support for our elderly citizens in the present neoliberal economic and political context of health care. To better understand how dominant discourses about dementia work at this time when Canada’s population is aging and the number of persons living with dementia is anticipated to increase, I have rooted my thesis in poststructural methodology. My research method is a discourse analysis, which draws on Foucault’s archaeological and genealogical concepts, to examine two contemporary health policy documents related to dementia care – one national and one provincial. I also incorporate some poetic representation – or found poetry – to write up my findings. While deconstructing and disrupting taken for granted dominant crisis discourses on dementia in health policy, my research also makes space for alternative constructions to support discursive and health policy possibilities in solidarity with persons living with dementia so that they may thrive. / Graduate / 0452 / 0680 / 0351 / macsuz@shaw.ca

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