Hemodynamics and Endothelial Cell Biology in Cardiovascular Diseases

Atherosclerotic plaques develop preferentially in curved and branching arteries in-vivo. Lipids and inflammatory cells accumulation in the intimal layer of the arterial wall is considered as the main driving mechanism in the disease progression. Evidences suggest that this focal distribution of plaques may result from the combination of systemic risk factors including high plasma cholesterol, smoking, diabetis, hypertension or genetic pre-disposition and local hemodynamic risk factors such as low and oscillatory flows. The exact mechanism of the biological and biomechanical interactions between the endothelium, blood flow and the growing lesion underneath still remains unclear. This thesis is a study on the relationship between biomechanical factors found in proatherogenic flow and endothelial inflammation. The thesis focuses in particular on the effect of secondary flows on wall shear stress and mass transport distribution. To that end, we have combined different techniques from flow imaging, 3D flow reconstruction, vascular biology and mathematical simulation of biological network. In particular, shear stress is involved in the regulation of the pro-inflammatory transcription factor nuclear factor -kB (NF-kB) and the vasoregulator Nitric Oxide. The role of endothelial Nitric Oxide and wall shear stress on NF-kB activation is still controversial. We investigated here the hypothesis that NO negatively regulates NF- kB activation in flow chamber with sheared endothelial cells and using a mathematical model of the NF-kB-NO pathway. Understanding the underlying relationship between hemodynamic factors and inflammatory cells transport to the wall may contribute to the development of better therapies or interventional practices to treat patients with atherosclerotic diseases

The Choice And Effect Of Mode Of Transportation In The Flow Of Agricultural Food Stuff In Rural Urban Flow: A Case Study Of Zaria Area

The study determined the choice and effect of modes of transportation in rural-urban flow of Agricultural food products to Zaria urban center. The primary data were obtained for the investigation using a structured sets of questionnaire. Descriptive statistics and regression analysis were used for the investigation. The results showed that cereal crops constitute the main grains in the area for sale. The specialization in the supply of food stuff to Zaria town conforms to Von Thunen's model of concentric. Zonation. Perishable and less bulky market garden products are supplied from areas immediately surrounding the urban area while others come from location of 16km and above. The study further showed that the most single means of transportation used to transport food grains to Zaria town is motor vehicle and closely followed by motor cycle. These means of transportation are used in combination with one or the other with one being dominant at one location. Also the distance of location from Zaria town appears to be the single most important factor affecting the use of one or the other means of available transportation system. It was observed that some means of transportation are rejected at certain points (locations) because of the degree of risk. Base on this finding, the following recommendations are put forward. That urban planners should identify the pre-urban critical thresholds over which motor vehicle transport is not enough so as to extend more town city motor vehicle services to move food stuff to Zaria Town. That town planners who exist separately from rural development planners should be replaced by a common central planning authority which can handle as a united issue all aspects of development planning, including transportation, both in the urban and rural areas. Samaru Journal of Information Studies Vol. 6 (1&2) 2006: pp. 19-2

Marketing Of Agricultural Food Grains In Selected Markets In Zaria Area

This study describes the organizational structure and marketing processes of the traditional agricultural marketing system with emphasis on the links between the village producer and the urban consumer using four food grains staple crops marketed in Zaria marketing area. The findings of the study showed that there is considerable organization in the marketing process and the intermediaries provide productive marketing services at reasonable costs given their technical environment. The study further showed that farmers received 78%, 79.4, 79.8 and 83% of the prices from the four major staple food grains. The analysis of inter-market price relationships revealed price spread in excess of transfer costs in the study area, implying imperfections in the markets. Other findings in the study discovered that traders do not have monopolistic power to attain such profits. Evidence supporting this view includes the finding that little storage takes place by traders in the urban daily market of Zaria. In the urban markets trader's monthly purchases are about equal to monthly sales. There is a conterminous flow of grains to these urban markets from the rural areas. The large amount of grains is stored by farmers. The Information Manager Vol. 6 (1&2) 2006: pp. 25-3

Sources and Accessibility of Credit to Farmers For Agricultural Financing In Makarfi Local Government Area of Kaduna State.

The study was carried out to determine the sources and accessibility of credit to farmers for agricultural financing in Makerifi Local Government Area of Kaduna State of Nigeria. Primary data was used for the study. Primary data was obtained using a structured set of questionnaire. Descriptive statistics and multiple regression analysis were used for the investigation. The result obtained show that 95.3% of the sampled farmers were between the age bracket of 21-50 years while 85.9% of the respondent had received one form of education or the other. 85.9% of the respondents have been farming for between 1 – 40 year. The result further revealed that 91.1% of the farmers in the area had 4 – 16 children as members of household size. The level of education and years of farming were the significant factors influencing access to credit by farmers in the area under study. 76.5% obtained loans from formal sources, while 23.5% got loans through informal sources. Further analysis, 24.7% of the farmers sampled, had problems of delay in approval and obtaining loans through formal sources while 4.7% of those sampled complained about delay in getting credit through informal sources. Based on the findings, the following recommendations were put forward. That there should be (i) minimization and simplification of procedures in obtaining loans from formal and information sources. This will enhance timely disbursement of loans to the farmers; and. Interest rates charged on loans by both formal and informal sources should be minimal. Samaru Journal of Information Studies Vol. 7 (2) 2007: pp. 34-3

The Impact of Road Network on Distribution of Social Amenities: A Case Study of Giwa Local Government Area of Kaduna State

The study focused on the effect of roads on the distribution of social amenities in Giwa Local Government Area of Kaduna State. It took a critical look at the road network connectivity and accessibility of the towns in Giwa in an attempt to understanding the level to which these road network components affected the distribution of social infrastructure. The data for this study was derived from secondary sources ; (i)The topology of the routes was extracted from the base map of the local government area, and this took some of the road network component. (ii)The statistical data on social amenities in the Local Government Area came from the various departments in the local government headquarters. A correlation analysis was applied on the data and the results tested for significance. Results of the study showed that the relationship between road network, and node accessibility and the distribution of social amenities, with a correlation coefficient explanation of 36.9%. The high disparity observed in the distribution of social amenities is the result of very poor connectivity index as revealed by the road network in the area. The Information Manager Vol. 7 (2) 2007: pp. 1-

The Application of Spatial Pattern Analysis in High School Level Geography

Geography is a vital subject of the school curriculum which is creative, practical and intellectually stimulating. It tries to identify features on the field, their spatial pattern as well as give explanations to process which have generated the observed distributional patterns their location and provide scientific explanation for the evolution of such patterns. It deals with concepts needed to develop a sharp geographical mind capable of appreciating and solving important spatial problems. This article examines the importance and application of core concepts, nature and observations needed to help students at high school.

L’Impact des corridors de la Région du Grand Mékong

À partir des années 1990, la Région du Grand Mékong (RGM), appuyée par la Banque Asiatique de Développement (BAD), développe l’approche des corridors dans l’objectif de favoriser l’intégration régionale en Asie du Sud-Est. Ces couloirs économiques, qui relient les centres de productions et de commerces, induisent à l’échelle des villes, de nouvelles relations de complémentarité et/ou de concurrence et une redéfinition de leurs fonctions urbaines. Due à sa localisation sur le corridor Nord-Sud, la ville de Chiang Rai, située au Nord de la Thaïlande, a connu un processus de reconfiguration urbaine et une spécialisation de ses fonctions politico-économiques. L’étude de ces récentes dynamiques permet de définir Chiang Rai comme une ville paire.Since the 1990s, the Greater Mekong Subregion (GMA), supported by the Asian Development Bank (ADB), has developed the corridors approach with the aim to promote regional integration in Southeast Asia. Economic corridors, which connect production and trade centers, induce at the scale of cities, new relations of complementarity and / or competition and a redefinition of their urban functions. Due to its location on the North-South Economic Corridor, Chiang Rai city, situated in northern Thailand, has undergone a process of urban reconfiguration and a specialization of its political and economic functions. The study of these recent dynamics allows to define Chiang Rai city as an urban pair

Outils de prédiction numérique pour l'optimisation des stratégies de contrôle du bruit à la source

L'objet principal de ce doctorat est le développement de techniques numériques permettant la réduction des nuisances sonores dues à la vibration de structures résonantes. Pour ce faire, des formulations théoriques originales ont été développées, puis implantées dans des codes numériques. Les résultats obtenus par ces codes ont fait l'objet d'une analyse minutieuse afin de dégager les principes physiques qui permettent de diminuer le rayonnement acoustique d'une structure soumise à des vibrations stationnaires. Dans le cadre de l'étude de l'amortissement d'une structure par l'ajout de matériaux viscoélastiques, une formulation théorique originale a été développée: elle traite le cas d'une plaque rectangulaire, bafflée, simplement appuyée et couverte par un traitement partiel, constitué d'une couche viscoélastique et d'une couche rigide. L'analyse des résultats a permis de mettre en évidence les points suivants: (1) L'existence d'un module d'Young optimum de la couche viscoélastique, qui entraîne un amortissement maximum des vibrations de la structure, a été montrée. (2) Dans le cas où l'on considère un traitement viscoélastique qui ne couvre qu'une partie de la plaque, on remarque que l'augmentation d'amortissement est une fonction logarithmique du pourcentage de couverture, ce qui signifie que l'amortissement augmente beaucoup entre 0% et 25% de couverture alors que la différence est très faible entre 75% et 100%. (3) Une méthode est proposée pour optimiser la position de la couverture partielle sur la plaque de base, pour les premiers modes de structure. Cette méthode consiste à rechercher les zones qui vont maximiser les déformations de cisaillement transversal dans la couche viscoélastique, car elles sont principalement responsables de la dissipation d'énergie. Pour les modes de haut-ordre, la position de la couverture importe peu, car la dimension de la couverture étant très supérieure à la longueur d'onde structurale, la même efficacité est obtenue quelle que soit la position de la couverture sur la plaque. Afin d'étudier l'isolation acoustique procurée par l'ajout d'un matériau de masquage sur une structure immergée dans l'eau, un modèle théorique a également été développé. La structure considérée est une plaque rectangulaire, bafflée, simplement appuyée et recouverte par un matériau de masquage. L'analyse des résultats montre que l'isolation obtenue par le matériau de masquage croit en fonction de la fréquence. De plus, la diminution de la rigidité du matériau de masquage améliore l'isolation acoustique de manière uniforme. La troisième partie de ce doctorat est consacrée au développement d'une méthode qui permet l'évaluation numérique du champ acoustique rayonné par une structure, à partir de la mesure de son champ de déplacement. Cette méthode a fait l'objet de nombreuses validations qui ont permis de montrer que bien qu'elle soit définie pour des structures planes, elle donne encore des résultats précis pour des structures avec une légère courbure."--Résumé abrégé par UM