Les pathologies du foie représentent une des causes les plus fréquentes de mortalité. Ceci provient sans doute de la difficulté de poser le diagnostic à un stade précoce de leur développement malgré les très bonnes performances de l'échographie et de la tomographie de rayons X. On espère que l'IRM dont les résultats spectaculaires dans le diagnostic des tumeurs cérébrales sont aujourd'hui incontestés améliorera la situation. Malheureusement, comme les autres techniques et en dépit de son excellent contraste inhérent, l'IRM se heurte aussi au problème de la mise en évidence des maladies hépatiques. Afin de remédier à cette situation, la recherche s'est orientée vers l'élaboration de produits de contraste spécifiques. La stratégie suivie jusqu'ici est double: d'une part, des complexes d'ions paramagnétiques sont développés pour favoriser leur incorporation par les hépatocytes, et, d'autre part, des nanoparticules superparamagnétiques sont synthétisées afin de cibler les cellules de Kupffer, les macrophages fixes du foie.

Tracer based MRI perfusion measurements is a clinically useful tool to assess regional distributions of tissue blood flow and volume. The method may be based on any of the three relaxation mechanisms T1, T1 and T2*, the latter denoted DSC-MRI being the most common. The primary aim of this work was to study the feasibility of obtaining quantitative estimates using these methods. 1) Feasibility of DSC-MRI for kidneys using an iron oxide based contrast agent and the influence of secondary relaxation effects on the results, part of a clinical phase II trial: The method proved feasible and the underestimation induced by secondary relaxation can be corrected for by using a double echo sequence. 2) Influence of blood flow rate on risk factors for developing cerebral ischemia during cardio pulmonary bypass, measurements in pig with gadolinium based DSC-MRI: The results indicated an ischemic threshold level at a blood flow rate of approximately 6 ml/kg/min. 3) The ability of gadolinium based DSC-MRI to detect changes in global blood flow, experimental measurements in pig and numerical simulations: The results support that DSC-MRI can discriminate between global flow levels in the same subject given that all other parameters are kept constant. The results also indicate that calculated perfusion values are highly sensitive to the arterial deconvolution procedure. 4) Influence of differences in blood/tissue relaxivity and secondary relaxation for a gadolinium based contrast agent, measurements in pig and numerical simulations: The blood/tissue relaxivity ratio is not unity and the situation is complicated by secondary relaxation effects. Deconvolution regularization appears to partly counteract the overestimation induced by difference in blood/tissue relaxivity for DSC-MRI. In summary, the fundamental assumption of equal blood and tissue relaxivity is experimentally shown to be invalid and the influence of this discrepancy is substantial. Several factors contribute to measurement errors, a combination of these factors can incidentally lead to additive errors or error cancellation based on a variety of experimental and analysis conditions. Given that the differences in blood/tissue relaxivity cannot readily be accounted for in a clinical setting, absolute perfusion quantification by tracer based MRI remains challenging if not impossible.

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The focus of this thesis is to better explore and understand the effects of agent interactions, information feedback, and adaptive learning in a repeated game of bidding in farmland auction markets. This thesis will develop a multi-agent model of farm-land auction markets based on data from the Saskatchewan Dark Brown Soil Zone of the Canadian Prairies. Several auction types will be modeled and data will be gathered on land transactions between farm agents to ascertain which auction type (if any) is best suited for farmland markets. Specifically, the model gathers information for 3 types of sealed-bid auctions, and 1 English auction and compares them on the basis of efficiency, price information revelation, stability, and with respect to repeated bidding and agent learning. The effects of auction choice on macro-level indicators, such as farm exits, retirement, financial stability, average productivity, farm size, and participation were unknown at the outset of this thesis because of the complex dynamic nature of the environment. I find that the chosen learning mechanism employed here affects both price and variance of prices in all auctions. I also find that the second-price-sealed-bid auction generates the most perceived surplus, most equitable share of surplus, and also decreases uncertainty in the common-value element of prices. A priori it was believed that auction choice would have an impact on pricing efficiency, price levels, and shares of surplus generated from auctions as predicted by theoretical works. Surprisingly, auction choice does not influence market structure or evolution.

Along with the development of the economy and technology, the network has become more important in people's work and life than before. More and more people take advantage of network to improve the quality of their work and life. The network applications are based on the database visiting, and the database visiting is almost based on the Distributed database. The Distributed data service can be widely used in the corporation and many important fields. More technology and solutions are proposed, including the Mobile Agent technology. Mobile Agent is a code segment that can migration in the network, carrying the task code, using network and computers' resource, cooperating with other MAs, finishing one or more designated tasks. Compared with other mobile code, the MA technology can use less network resource, carry less information, and operate with higher efficiency. Using the technology to solve distributed problems is a hot research topic currently. In this paper, we first review the current research status in the Mobile Agent and distributed data service fields. After that, based on the current issues in the Distributed data service fields, we propose a complete solution using the Mobile Agent technology. Last, with the proposed solution, we construct a complete distributed data service model. In our solution, the traditional Distributed data-retrieving procedure is investigated and enhanced with the Mobile Agent technology to achieve high efficiency. The Mobile Agent related technology, such as MA communication, MA security, and MA cooperation technology are also used to improve the model 's efficiency and reduce the network's cost. We have used a project management system as a sub-model. Compared with the traditional approaches, the model works more efficiently with larger number of stations and large amount of the data-request. Finally, detailed analyzing of one instance is presented to show the characteristic of the model.

The focus of this thesis is to better explore and understand the effects of agent interactions, information feedback, and adaptive learning in a repeated game of bidding in farmland auction markets. This thesis will develop a multi-agent model of farm-land auction markets based on data from the Saskatchewan Dark Brown Soil Zone of the Canadian Prairies. Several auction types will be modeled and data will be gathered on land transactions between farm agents to ascertain which auction type (if any) is best suited for farmland markets. Specifically, the model gathers information for 3 types of sealed-bid auctions, and 1 English auction and compares them on the basis of efficiency, price information revelation, stability, and with respect to repeated bidding and agent learning. The effects of auction choice on macro-level indicators, such as farm exits, retirement, financial stability, average productivity, farm size, and participation were unknown at the outset of this thesis because of the complex dynamic nature of the environment. I find that the chosen learning mechanism employed here affects both price and variance of prices in all auctions. I also find that the second-price-sealed-bid auction generates the most perceived surplus, most equitable share of surplus, and also decreases uncertainty in the common-value element of prices. A priori it was believed that auction choice would have an impact on pricing efficiency, price levels, and shares of surplus generated from auctions as predicted by theoretical works. Surprisingly, auction choice does not influence market structure or evolution.

Begreppet ansvarsredovisning har många olika meningar, och har fått en allt större betydelse för företagens kommunikation. Samhället ställer krav på organisationernas och företagens etik, sociala ansvar och miljöansvar enligt litteraturen. Trots dessa krav är företagens och organisationernas ansvarsredovisning till stor del frivillig. Den lågkonjunktur som råder i Sverige och i övriga världen kan också antas ha påverkat kraven på företagen, att ta ett större samhälligt ansvar. Allmänheten ställer också större krav på att informationen redovisas på ett korrekt sätt, och att informationen är tillförlitlig. Syftet med denna uppsats är att utifrån studiens frågor beskriva innebörden av begreppet ansvarsredovisning. Resultatet visar att ansvar har en teknisk innebörd som kräver tekniska färdigheter och kommunikation, men har även en social dimension som blir allt viktigare. Hur kan ansvarsredovisning beskrivas i ett organisatoriskt sammanhang, samt den tekniska dimensionen av ansvarsredovisningen? Vi har studerat organisationen ur ett organisatoriskt perspektiv. Studiens resultat karakteriseras genom två olika former, den sociala och den tekniska. Studien är baserad på det induktiva perspektivet. Undersökningsstrategin är deskriptiv och explorativ. Vi använder en multipel teoretisk referensram för att berika analysen av insamlade materialet. Tillämpning av multipla teorier resulterade i en i en klar koppling mellan teori och praktik. Företag och organisationer vill framstå i ”god dager” i media som en ansvarsfull enhet.Ansvarsredovisning balanserar förhållandet mellan intressenters krav och företagens och organisationernas ansvar.Ansvarsredovisningens betydelse ökar stadigt, trots att lagkravet för ansvarsredovisning är minimalt. Vi tror att ansvarsredovisningen har kommit för att stanna.

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With the development of mobile devices, people can execute many applications on their personal devices at any time and in any place. However, many limitations of the mobile devices, e.g., CPU, memory, power supply, etc., make them impossible to be completely the same as the desktop PCs. In this paper we present an integrated management architecture for thin-client purpose called Agent and Profile Management System (APMS). The users of mobile devices can use the services from various service providers via this system. On the other hand, the centralized management of service agents provided by the service providers is employed in this system. The users only need to download a simple service agent to their mobile device and install it, then the service agent will connect to the homologous service provider, send an XML-RPC request by ¡§POST¡¨ to the back-end server. After receiving the XML-RPC request, the back-end server executes appropriate processes and returns an XML-RPC response to the mobile device. Most of the procedures are accomplished on the server side that has powerful CPU and large amount of memory. Therefore, the loading of mobile devices is relatively low and the cost of mobile devices can be effectively reduced.