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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.
1

Field observation and analysis of the growth and decay of Typhoon induced swell and wind-waves at southwest coastal Taiwan

Hsu, Tang-Chia 13 February 2007 (has links)
During the typhoon season, the coastal Taiwan often receives swells follow by wind waves. The routes of typhoon and the geographic effects complicate the wave conditions. This study investigates the growth and decay of waves at the southwest coast of Taiwan due to two different paths of typhoon. Two different methods of wave analysis are applied: The Fast Fourier Transform (FFT), and the Hilbert Huang Transform (HHT). The results show that 1) the FFT analysis is simple and easy to apply. The HHT, however, provides detail information on wave height and period during typhoon passages. The typhoon went through northern Taiwan induced small waves and period. The reason is that the wind is blocked by the Central Ridge of Taiwan. Waves are generated after typhoon center pass the Taiwan Strait. 2) On the other hand, typhoon went though Luzon Strait induced large swells and wind waves. The geographic effect is the major factor of wave height and period generated. The distance to the typhoon center is another factor producing large waves which is related to the degree of gust. 3) The comparison of wind wave and swell show that the sea is dominated by wind waves during the approaching of typhoon, while swells dominate over when typhoon is leaving.
2

N-linked glycosylation at position ASN98 of the ALK1 receptor protein: relevance for ALK1 function and HHT pathogenesis

Gadaleta, Erick Michael 18 June 2016 (has links)
Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant genetic disorder that results from a mutation of one of two key signaling receptors for the transforming growth factor beta (TGFβ) superfamily: endoglin and activin receptor-like kinase 1 (ALK1). These mutations result in development of HHT Type 1 and HHT Type 2, respectively. Patients suffering from HHT experience spontaneous blood vessel growth that can lead to telangiectasia, arteriovenous malformation (AVM) development, and other related health problems. ALK1 is a serine/threonine kinase receptor found on the cell membrane of endothelial cells. ALK1 and its co-receptor endoglin, are activated by binding to the circulating BMP9 ligand. The ALK1-endoglin-BMP9 complex will then regulate endothelial proliferation by activating the SMAD pathway by phosphorylation. Mutations in the ACVRL1 gene can form a modified ALK1 protein that has a high potential to inhibit this function, causing the hyperproliferation of endothelial cells and the development of AVMs, and ultimately HHT Type 2. It is believed, however unproven, that ALK1 is heavily glycosylated in the extracellular domain. My thesis research was aimed at studying the glycosylation of ALK1 and at exploring the relevance of this glycosylation to the development of HHT. The glycosylation of ALK1 was investigated by using: (i) a computational prediction approach (NetNGlyc 1.0 bioinformatics server), (ii) a glycosylation inhibiting drug (tunicamycin), (iii) an in vitro enzymatic approach of glycosylation breakdown, and (iv) site-directed mutagenesis to identify the ASP residue glycosylated on ALK1. The bioinformatics software NetNGlyc predicted a N-linked glycosylation site on an asparagine (ASN) residue located at position 98 in the extracellular domain of ALK1. I further found that, based on western blot analysis, ALK1 proteins shifted to a lighter molecular weight (5-8 kDa) when treated with tunicamycin, as well as endo H and PNGase F enzymes, which represent two glycosidases able to remove N-linked oligosaccharides on proteins. Western blot analysis also revealed an identical shift in protein size (5-8 kDa) when comparing wild type ALK1 to an asparagine98-to-alanine (N98A) mutant ALK1 construct. The 5-8 kDa shift observed in the drug and enzymatic experiments indicate the removal of a bulky oligosaccharide from the wild type ALK1 protein. This 5-8 kDa shift observed in the mutagenesis experiment indicated that the same oligosaccharide addition could not occur on ALK1 when ASP98 was missing. Thus proving that the asparagine at the 98th position of ALK1 is involved in N-linked glycosylation. These important findings on ALK1 modification offer a greater understanding of the mechanisms behind ALK1 regulation and function, especially its role in controlling angiogenesis. Furthermore, this data provides grounds for further research into the importance of ALK1 glycosylation in the pathogenesis of HHT, as well as the investigation into new treatment regiments.
3

Experimental Study on the Interaction between Surface Wave and Internal Wave

Lai, Keng-chen 25 July 2009 (has links)
Surface gravity waves and internal waves are two of the most common natural phenomena in the ocean. While oceanographers believe that internal waves have greater influence over the surface waves, if is not clear to what extent that the former have affected the latter. As an internal wave propagating in the ocean, short period flow could be induced on the free surface layer. Moreover, as internal waves propagating over a submarine ridge, internal breaking accompanying by large vortex may have occurred, which may also affect the properties of the surface waves. To prove the relationship between them, basic mathematical equations have been derived, but had never been proven in the laboratory experiments or field observations. In this thesis, the results of a series of laboratory experiments conducted at the National Sun Yen-sen University are employed to study the waveform evolution and change to the physical parameters of the surface waves, resulting from the generation of internal waves induced on a stratified fluid, as both propagate together above a plane bottom or across single ridge. These experiments were carried out in a stratified two-layer fresh/brine water system (upper layer with fresh water density 996 kg / m3; bottom layer brine water with 1030 kg / m3) in a steel framed wave tank of 12m long with cross-section of 0.7 m high by 0.5 m wide. A plunging-type wave maker was used to produce the designated surface waves, from which the internal waves were induced at the interface. Based on the experimental results in the fluid system with uniform density, wave height and period of the surface wave were first calibrated. It was found that the amplitude of a surface wave decreased first due to the breaking of the internal wave on the apex of a submerged ridge and then increased due to wave regeneration at the back of the ridge, when the surface wave propagated over single ridge. Beyond the ridge, the peak period with maximum energy associated with the transmitted wave remained almost the same with that of the incident waves. In a stratified fluid system, wave height of the surface waves and internal waves did not suffer much change but the peak period of a surface wave increased as an internal wave just across the apex of the obstacle, under a condition referred to as weaken interaction between the waves and the obstacle. For the intense wave breaking condition at the interface, wave height of the internal waves decreased and the period of surface waves or internal waves shortened. However, wave height of the surface wave above the apex of the obstacle increased due to the intense wave breaking. The results obtained from the present laboratory experiments on the interaction between a surface wave and the induced internal wave could benefit others interested in surface and internal wave interaction for practical applications in oceanography or numerical modeling.
4

Prevalence and Predictors of HHT and CM-AVM Syndrome Among Children with Neurovascular Malformations

Engel, Elissa 05 June 2023 (has links)
No description available.
5

ALK1 et BMP9 dans le remodelage vasculaire de la génétique humaine aux modèles murins / ALK1 / BMP9 and vascular remodeling From human genetics to murin models

Ricard, Nicolas 23 September 2011 (has links)
ALK1 est un récepteur de la famille du TGF-β, principalement exprimé dans les cellules endothéliales. Le ligand physiologique et circulant d'ALK1, BMP9, a été découvert par notre laboratoire en 2007, ce qui a ouvert des possibilités d'étude de la fonction d'ALK1. La première partie de ma thèse a été consacrée à l'analyse fonctionnelle de mutants d'ALK1, retrouvés sur des patients atteints de la maladie de Rendu-Osler de type 2, en réponse à BMP9. Cette étude a permis de : 1) proposer l'haploinsuffisance fonctionnelle comme modèle de la maladie ; 2) développer un test diagnostique pour discriminer les mutations pathogènes des polymorphismes rares, basé sur leur réponse à BMP9 ; 3) d'avoir une meilleure connaissance des acides aminés d'ALK1 importants dans la réponse à BMP9. Un second travail a consisté en la production de la forme mature de BMP9 et du domaine extracellulaire d'ALK1 en vue de l'étude de la structure cristallographique du complexe. L'expression des protéines et leur purification sont en phase d'optimisation. Enfin, un troisième projet consistait en l'analyse du rôle de BMP9 dans l'angiogenèse in vivo. La neutralisation de BMP9 par deux stratégies distinctes induit une augmentation de la densité vasculaire dans la rétine de la souris. Le mécanisme est en cours d'investigation. / ALK1 is a TGF-β family receptor, mainly expressed on endothelial cells. The physiologic and circulating ligand of ALK1, BMP9, was discovered by our laboratory in 2007, which opened opportunities for studying the function of ALK1. The first part of my thesis was on the functional analysis of ALK1 mutants from HHT-2 patients in response to BMP9. This study allowed us to: 1) propose functional haploinsufficiency as a model for HHT-2; 2) develop a diagnostic tool to discriminate pathogenic mutations from rare polymorphisms, based on their BMP9 response; 3) increase our knowledge of important amino acids in ALK1 for the BMP9 response. A second work was on the production of the mature form of BMP9 and of the extracellular domain of ALK1 in order to study the crystallographic structure of the complex. The expression of these proteins and their purification are in optimization phase. Lastly, a third project was on the analysis of the role of BMP9 in angiogenesis in vivo. Neutralization of BMP9 using two strategies induces an increase of the vascular density of the retina in mouse. Mechanism of action is under investigation.
6

Multi-scale controls on spatial patterns of soil water storage in the hummocky regions of North America

Biswas, Asim 11 July 2011
The intensification of land-water management due to agriculture, forestry, and urbanization is a global phenomenon increasing the pressure on worlds water resources and threatening water security in North America. The Prairie Pothole Region of North America covers approximately 775,000 km2 and contains millions of wetlands that serve important hydrological and ecological functions. The unique hummocky topography and the variable effect of different processes contribute to high spatio-temporal variability in soil water, posing major challenges in hydrological studies. The objectives of this study were to a) examine the spatial pattern of soil water storage and its scale and location characteristics; and b) to identify its controls at multiple scales. Soil water content at 20 cm intervals down to 140 cm was measured along a transect extending over several knolldepression cycles in a hummocky landscape. High water storage in depressions and low water storage on the knolls created a spatial pattern that was inversely related to elevation. Spatial patterns were strongly similar within any given season (intra-season rank correlation coefficient as high as 0.99), moreso than between the same season over different years (inter-annual rank correlation coefficient as high as 0.97). Less similar spatial patterns were observed between different seasons (inter-season rank correlation coefficients as high as 0.90). While the intra-season and inter-annual spatial patterns were similar at scales >18 m, the inter-season spatial patterns were similar at much large scales (>72 m). This may be due to the variations in landform elements and micro-topography. The similarity at scales >72 m were present at any time and depth. However, small- and medium-scale spatial patterns changed with depth and with season due to a change in the hydrological processes. The relative dominance of a given set of processes operating both within a season and for the same season over different years yielded strong intra-season and inter-annual similarity at scales >18 m. Moreover, similarity was stronger with increasing depth, and was thought to be due to the dampening effect of overlying soil layers that are more dynamic. Similarity of spatial patterns over time helps to identify the location that best represents the field averaged soil water and improves sampling efficiency. Change in the similarity of scales of spatial pattern helps identify the change in sampling domain as controlled by hydrological processes. The scale information can be used to improve prediction for use in environmental management and modeling of different surface and subsurface hydrological processes. The similarity of spatial pattern between the surface and subsurface layers help make inferences on deep layer hydrological processes as well as groundwater dynamics from surface water measurements.
7

Multi-scale controls on spatial patterns of soil water storage in the hummocky regions of North America

Biswas, Asim 11 July 2011 (has links)
The intensification of land-water management due to agriculture, forestry, and urbanization is a global phenomenon increasing the pressure on worlds water resources and threatening water security in North America. The Prairie Pothole Region of North America covers approximately 775,000 km2 and contains millions of wetlands that serve important hydrological and ecological functions. The unique hummocky topography and the variable effect of different processes contribute to high spatio-temporal variability in soil water, posing major challenges in hydrological studies. The objectives of this study were to a) examine the spatial pattern of soil water storage and its scale and location characteristics; and b) to identify its controls at multiple scales. Soil water content at 20 cm intervals down to 140 cm was measured along a transect extending over several knolldepression cycles in a hummocky landscape. High water storage in depressions and low water storage on the knolls created a spatial pattern that was inversely related to elevation. Spatial patterns were strongly similar within any given season (intra-season rank correlation coefficient as high as 0.99), moreso than between the same season over different years (inter-annual rank correlation coefficient as high as 0.97). Less similar spatial patterns were observed between different seasons (inter-season rank correlation coefficients as high as 0.90). While the intra-season and inter-annual spatial patterns were similar at scales >18 m, the inter-season spatial patterns were similar at much large scales (>72 m). This may be due to the variations in landform elements and micro-topography. The similarity at scales >72 m were present at any time and depth. However, small- and medium-scale spatial patterns changed with depth and with season due to a change in the hydrological processes. The relative dominance of a given set of processes operating both within a season and for the same season over different years yielded strong intra-season and inter-annual similarity at scales >18 m. Moreover, similarity was stronger with increasing depth, and was thought to be due to the dampening effect of overlying soil layers that are more dynamic. Similarity of spatial patterns over time helps to identify the location that best represents the field averaged soil water and improves sampling efficiency. Change in the similarity of scales of spatial pattern helps identify the change in sampling domain as controlled by hydrological processes. The scale information can be used to improve prediction for use in environmental management and modeling of different surface and subsurface hydrological processes. The similarity of spatial pattern between the surface and subsurface layers help make inferences on deep layer hydrological processes as well as groundwater dynamics from surface water measurements.
8

Application of HHT to temperature variations at the thermal outlet of Third Nuclear Power Station

Wu, Wei-lih 22 March 2005 (has links)
Nan Wan is a half-closed embayment in the most southern part of Taiwan. While facing the Luzon Strait, it also connects to the Pacific Ocean in its southeast, and is adjacent the Taiwan Strait and the South China Sea . In view of general oceanic circulation, Nan Wan Bay happens to lie to the rim of South China Sea circumfluence and Kuroshio where a variety of water mass exchange has taken place, causing saline intrusion and mixed of water. Seasonal variation and tidal fluctuations also contribute to the exchange of water masses. The Third Nuclear Power Station of Taiwan Power Company is located in Nan Wan with its thermal discharge outlet adjacent to Maobitou to the west of the bay in order to minimize the effect of warm water discharge on the local marine ecology and coral . A long-term monitoring program on water temperature and other environmental factors has been set up implemented .this research report will first describe the archives regarding the hydrology in Nan Wan in support of monitoring the process in temperature variation . Previous research efforts are found somehow unable reveal precisely the physical mechanism leading to water temperature variations in the bay, due to limited facilities, short of information or poor analytical tools. This report adopts 14 records of water temperature at the thermal outlet of the Third Nuclear Power Station for signal analysis. As to non-linear and unstable data analysis, it is based on the Hilbert-Huang Transform. HHT includes Empirical Mode Decomposition, EMD which could decompose the raw data into numerous Intrinsic Mode Function, IMF. It is allowed to comprehend the main causes for the rising and dropping of water temperature based on the variation of spectroscopy by transferring through Hilbert and analyzing via IMF. Furthermore, the characteristic of each quantity could be developed according to the quantities acquired from the former method of HHT. The analytical report of water temperature covers 14 records dating from 1999 to 2003. In light of the analytical report, tide and wind account for the main cause of the temperature variation in waters while demanding information to ensure whether it is influenced by other factors like internal waves, water masses or landforms, etc. In addition, the report compares the difference in the same of data between FFT and HHT and moreover concludes the advantages and disadvantages as reference for researches.
9

Zur molekulargenetischen Charakterisierung der Mutationen in den Endoglin-und ACVRL1-Genen bei den Morbus-Osler-Patienten / Moleculargenetic characterization of mutations in the Endoglin and ACVRL1 genes in patients with Osler-Weber-Rendu Syndrome

Panchulidze, Irakli 21 September 2011 (has links)
No description available.
10

Diagnostic de la somnolence d'un opérateur: analyse automatique de signaux physiologiques

Sharabaty, Hassan 05 December 2007 (has links) (PDF)
Depuis plusieurs années le LAAS-CNRS travaille sur la problématique de la détection de la baisse de vigilance d'un conducteur d'automobile à partir de l'analyse du mode de conduite, afin de réduire le grand nombre des accidents routiers. Dans ce contexte, nous nous sommes intéressés de dégager une mesure référante de l'hypovigilance qui permettrait, par comparaison, de valider le système de mesure embarqué associant des mesures comportementales. Cette thèse a porté sur l'analyse automatique des signaux physiologiques (EEG, EOG) permettant de caractériser la somnolence; et s'est inscrit dans le cadre du projet européen SENSATION. Ce travail s'articule en 2 parties. La première est dédiée à l'analyse des EEG et commence par une présentation de la forme d'onde des signaux à analyser et des phénomènes représentatifs de la somnolence, puis des techniques d'analyse susceptibles de répondre au problème posé : transformé de Fourier, décomposition en Ondelettes, transformation de Hilbert Huang; Pour la suite de l'étude, nous avons sélectionnée la transformation de Hilbert-Huang. La précision de cette méthode sera étudier qualitativement, avant de présenter l'algorithme développé et les premiers résultats obtenus sur des signaux réels. Les conclusions de l'analyse de la précision nous ont amené à modifier l'algorithme proposé par Huang en normalisant les composantes fournies par la transformation de Huang sur l'ensemble de la fenêtre d'analyse avant application de la transformation de Hilbert. La deuxième partie de la thèse est donc consacrée à la localisation et la caractérisation des clignements des yeux dans l'EOG. Avant de présenter l'algorithme développé, nous décrivons le signal étudié et le modèle de clignement proposé. Nous comparons ensuite, sur une base de données constituée durant des expériences menées sur un simulateur de conduite, les résultats obtenus par notre algorithme à une analyse semi-automatique. Une fois la détection des clignements validée, nous com parons le degré de somnolence déterminé après mise en place des règles utilisées par les experts à l'analyse visuelle des signaux. Le bilan du travail réalisé et les perspectives d'amélioration des résultats concluront ce travail.

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