36 resultados para Imaging systems in medicine


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The investigation of renal pathophysiology and toxicology has traditionally been advanced by the development of increasingly defined and refined in vitro preparations. This study has sought to develop and evaluate various methods of producing pure samples of renal proximal tubules (PTs) from the Fischer rat. The introduction summarised the most common in vitro preparations together with the parameters used to monitor viability - particularly with regard to toxic events. The most prevalent isolation methods have involved the use of collagenase to produce dissociation of the cortex. However, the present study has shown that even the mildest collagenase treatment caused significant structural damage which resulted in a longevity of only 3hr in suspension. An alternative mechanical isolation technique has been developed in this study that consists of perfusion loading the renal glomeruli with Fe304 followed by disruption of the cortex by homogenisation and sequential sieving. The glomeruli are removed magnetically and the PTs then harvested by a 64μM sieve. PTs isolated in this way showed a vastly superior structural preservation over their collagenase isolated counterparts; also oxygen consumption and enzyme leakage measurements showed a longevity in excess of 6hr when incubated in a very basic medium. Attempts were then made to measure the cytosolic calcium levels in both mechanical and collagenase isolated PTs using the fluorescent calcium indicator Fura. However results were inconclusive due to significant binding of the Fura to the external PT surfaces. In conclusion, PTs prepared by the present mechanical isolation technique exhibit superior preservation and longevity compared with even the mildest collagenase isolation technique and hence appear to offer potential advantages over collagenase isolation as an in vitro renal system.

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This thesis includes analysis of disordered spin ensembles corresponding to Exact Cover, a multi-access channel problem, and composite models combining sparse and dense interactions. The satisfiability problem in Exact Cover is addressed using a statistical analysis of a simple branch and bound algorithm. The algorithm can be formulated in the large system limit as a branching process, for which critical properties can be analysed. Far from the critical point a set of differential equations may be used to model the process, and these are solved by numerical integration and exact bounding methods. The multi-access channel problem is formulated as an equilibrium statistical physics problem for the case of bit transmission on a channel with power control and synchronisation. A sparse code division multiple access method is considered and the optimal detection properties are examined in typical case by use of the replica method, and compared to detection performance achieved by interactive decoding methods. These codes are found to have phenomena closely resembling the well-understood dense codes. The composite model is introduced as an abstraction of canonical sparse and dense disordered spin models. The model includes couplings due to both dense and sparse topologies simultaneously. The new type of codes are shown to outperform sparse and dense codes in some regimes both in optimal performance, and in performance achieved by iterative detection methods in finite systems.

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Over the past decade or so a number of changes have been observed in traditional Japanese employment relations (ERs) systems such as an increase in non-regular workers, a move towards performance-based systems and a continuous decline in union membership. There is a large body of Anglo-Saxon and Japanese literature providing evidence that national factors such as national institutions, national culture, and the business and economic environment have significantly influenced what were hitherto three ‘sacred’ aspects of Japanese ERs systems (ERSs). However, no research has been undertaken until now at the firm level regarding the extent to which changes in national factors influence ERSs across firms. This article develops a model to examine the impact of national factors on ER systems; and analyses the impact of national factors at the firm level ER systems. Based on information collected from two different groups of companies, namely Mitsubishi Chemical Group (MCG) and Federation of Shinkin Bank (FSB) the research finds that except for a few similarities, the impact of national factors is different on Japanese ER systems at the firm level. This indicates that the impact of national factors varies in the implementation of employment relations factors. In the case of MCG, national culture has less to do with seniority-based system. Study also reveals that the national culture factors have also less influence on an enterprise-based system in the case of FSB. This analysis is useful for domestic and international organizations as it helps to better understand the role of national factors in determining Japanese ERSs.

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Re-emphasizing the need to examine human resource management (HRM) in context, this article builds around four themes. First, it analyses the main issues discussed in the existing literature regarding HRM in the Asian context. Second, it highlights the critical challenges facing HRM function in the region. Third, along with the analysis, it presents an agenda for future research. Fourth, it presents a framework useful for highlighting the context specific nature of Asian HRM functions and the main determinants of HRM policies and practices from a cross-national comparative perspective.

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DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

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DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

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DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

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The primary questions addressed in this paper are the following: what are the factors that affect students’ adoption of an e-learning system and what are the relationships among these factors? This paper investigates and identifies some of the major factors affecting students’ adoption of an e-learning system in a university in Jordan. E-learning adoption is approached from the information systems acceptance point of view. This suggests that a prior condition for learning effectively using e-learning systems is that students must actually use them. Thus, a greater knowledge of the factors that affect IT adoption and their interrelationships is a pre-cursor to a better understanding of student acceptance of e-learning systems. In turn, this will help and guide those who develop, implement, and deliver e-learning systems. In this study, an extended version of the Technology Acceptance Model (TAM) was developed to investigate the underlying factors that influence students’ decisions to use an e-learning system. The TAM was populated using data gathered from a survey of 486 undergraduate students using the Moodle based e-learning system at the Arab Open University. The model was estimated using Structural Equation Modelling (SEM). A path model was developed to analyze the relationships between the factors to explain students’ adoption of the e-learning system. Whilst findings support existing literature about prior experience affecting perceptions, they also point to surprising group effects, which may merit future exploration.

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Radio-frequency identification technology (RFID) is a popular modern technology proven to deliver a range of value-added benefits to achieve system and operational efficiency, as well as cost-effectiveness. The operational characteristics of RFID outperform barcodes in many aspects. One of the main challenges for RFID adoption is proving its ability to improve competitiveness. In this paper, we examine multiple real-world examples where RFID technology has been demonstrated to provide significant benefits to industry competitiveness, and also to enhance human experience in the service sector. This paper will explore and survey existing value-added applications of RFID systems in industry and the service sector, with particular focus on applications in retail, logistics, manufacturing, healthcare, leisure and the public sector. © 2012 AICIT.