Heart disease is attributed as the highest cause of death in the world. Although this could be alleviated by heart transplantation, there is a chronic shortage of donor hearts and so mechanical solutions are being considered. Currently, many Ventricular Assist Devices (VADs) are being developed worldwide in an effort to increase life expectancy and quality of life for end stage heart failure patients. Current pre-clinical testing methods for VADs involve laboratory testing using Mock Circulation Loops (MCLs), and in vivo testing in animal models. The research and development of highly accurate MCLs is vital to the continuous improvement of VAD performance. The first objective of this study was to develop and validate a mathematical model of a MCL. This model could then be used in the design and construction of a variable compliance chamber to improve the performance of an existing MCL as well as form the basis for a new miniaturised MCL. An extensive review of literature was carried out on MCLs and mathematical modelling of their function. A mathematical model of a MCL was then created in the MATLAB/SIMULINK environment. This model included variable features such as resistance, fluid inertia and volumes (resulting from the pipe lengths and diameters); compliance of Windkessel chambers, atria and ventricles; density of both fluid and compressed air applied to the system; gravitational effects on vertical columns of fluid; and accurately modelled actuators controlling the ventricle contraction. This model was then validated using the physical properties and pressure and flow traces produced from a previously developed MCL. A variable compliance chamber was designed to reproduce parameters determined by the mathematical model. The function of the variability was achieved by controlling the transmural pressure across a diaphragm to alter the compliance of the system. An initial prototype was tested in a previously developed MCL, and a variable level of arterial compliance was successfully produced; however, the complete range of compliance values required for accurate physiological representation was not able to be produced with this initial design. The mathematical model was then used to design a smaller physical mock circulation loop, with the tubing sizes adjusted to produce accurate pressure and flow traces whilst having an appropriate frequency response characteristic. The development of the mathematical model greatly assisted the general design of an in vitro cardiovascular device test rig, while the variable compliance chamber allowed simple and real-time manipulation of MCL compliance to allow accurate transition between a variety of physiological conditions. The newly developed MCL produced an accurate design of a mechanical representation of the human circulatory system for in vitro cardiovascular device testing and education purposes. The continued improvement of VAD test rigs is essential if VAD design is to improve, and hence improve quality of life and life expectancy for heart failure patients.

This study examines the operating costs of, and intentional compliance with, the value added tax (VAT) in Ethiopia. The study focuses on assessing the magnitude and nature of operating costs, identifying areas in the design and administration of the tax that contribute to the operating costs and the problems in the operation of the tax at large, and also on the link between VAT compliance costs and intentional output VAT reporting compliance decisions. The study adopts a mixed methods research approach to test a series of hypotheses and answer research questions that emerge through the review of existing literature and the experiences of the researcher in respect of the Ethiopian tax system. Specifically, the study uses surveys of taxpayers and tax practitioners, experimental design, interviews with tax officials and documentary analysis. The study statistically analyses the data elicited from the surveys and experimental design. It also analyses the results of in-depth interviews with tax officials and examination of documents held by tax authorities and other institutions. The results of this combined research methodology reveal that VAT operating costs in Ethiopia in the fiscal year 2005/06 appear to be relatively low. However, this low level of operating costs may not imply that the VAT system in Ethiopia is simple. In particular, in the case of administrative costs it is argued that it may indicate that the tax authorities are under-resourced which in turn may have affected their ability to accomplish the responsibilities entrusted to them. In respect of compliance costs, although the total costs seem to be low, it is contended that their regressiveness is likely to impact on the equity of the tax system as a whole. Further, the results show that VAT compliance costs and intentional VAT reporting compliance decisions are inversely correlated; but this correlation is statistically weak. The results also identify several concerns in the design and administration of the tax that have bearing on the operating costs and the operation of the tax. Specifically, the existence of the relatively high registration threshold, the high frequency of VAT reporting, the use of the invoice method of accounting (the latter two pertain mainly to small businesses) and weak administration are noted. iv The thesis suggests a series of measures which could be taken by the government and by the tax authorities in particular, to address the various problems identified in the study. These measures include strengthening the administration; allowing small businesses to adopt the cash basis of accounting and report less frequently; and reducing the registration threshold. The use of tax education is also emphasised as a strategy to improve compliance.

This research aimed to develop a deeper understanding of trust and non-profit agency website design, and specifically focussed on the ‘Donate Now’ button. Two experiments investigated the effects of varying levels of consumer certainty, manipulated by providing varying levels of donation relevant information on the web homepage donation buttons, on aid agency trust and donation compliance. Both experiments were based on Study 1, a preliminary survey of website donation button design. Experiment 1 investigated the effects of iconic manipulation of the ‘Donate Now’ button. Results suggested that varying levels of consumer certainty through iconic manipulation of the website donation button design did not effect aid agency trust and donation compliance. Experiment 2 extended the research of Burt and Dunham (2009) to investigate the effects of varying consumer certainty levels through the provision of crisis/need and response photographs on the donation buttons. Results suggested that whilst there was no effect of level of certainty on donation compliance, there was an effect on aid agency trust. Participants’ rated aid agency trust was increased to the greatest extent in the level of greatest certainty, when the donation button contained photographs of both the crisis/need and agency response. Collectively, these results suggest that aid agency trust can be enhanced through the considered manipulation of donation button design. Subsequently photographic images may be a more effective means with which to portray donation-relevant information and reduce uncertainty. Furthermore, in both experiments results showed that those individuals who reported higher aid agency trust also reported significantly higher donation intention. Thus, the current research has implications for the non-profit sector, suggesting that whilst the internet is a viable fundraising tool, the commercially driven process of online donation generation should not be isolated from the psychological concept of trust.

Doctor of Philosophy / Asthma can be a chronic disorder requiring regular medications if the symptoms are persistent. The regimen is often complex, involving a number of drugs and a variety or routes of administration. Although drug therapy may not alter the natural history of asthma it can improve lung function enabling those with asthma to lead as near a normal life as possible. Thus medication compliance is an important factor in the managemnt of asthma. (Note : Special enclosures (Publication reprints) at end of thesis have been removed for digital submission, with permission of author)

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for: Dept. of Psychology. Bibliography: leaves 119-132. Available online via the Internet.

Thesis (M.S.)--Purdue University, 2006. / Includes bibliographical references (leaves 91-96). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Doctoraalscriptie Rotterdam. / Omslagtitel. Lit. opg.: bl. 47-51. - Met een samenvatting in het Engels en Nederlands.

Thesis (Ph. D.)--Virginia Commonwealth University, 2007. / Prepared for : School of Education. Bibliography: leaves 100-112. Also available online via the Internet.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 77-90).

Thesis (M.P.H.M. (Primary Health Care Management))--Mahidol University, 2005.