A theoretical study of left ventricular and heart muscle dynamics

The characteristics of the left ventricle of the human heart considered as a pump have been extensively analysed. Using a new approach relying heavily on the Tensor Calculus, a theoretical model describing the mechanical and dynamical operation of the left ventricle has been developed. This has considerably greater versatility than previously proposed models. In particular the physiological shape, both under normal as well as many abnormal situations, is realistically simulated. Further, the mechanical behaviour of the ventricular wall is synthesised from anatomical data concerning the cardiac muscle fibre structure of the wall. Its mechanical and dynamical properties are then, as in the physiological situation, dependent on those of the muscle fibre. These fibre properties have also been fully investigated and a simple new model for cardiac muscle dynamics, incorporating active state, proposed. This description of the ventricular behaviour in terms of muscle properties represents the first logically structured link between cardiac muscle fibre characteristics and ventricular performance

HIV/AIDS: global trends, global funds and delivery bottlenecks

Globalisation affects all facets of human life, including health and well being. The HIV/AIDS epidemic has highlighted the global nature of human health and welfare and globalisation has given rise to a trend toward finding common solutions to global health challenges. Numerous international funds have been set up in recent times to address global health challenges such as HIV. However, despite increasingly large amounts of funding for health initiatives being made available to poorer regions of the world, HIV infection rates and prevalence continue to increase world wide. As a result, the AIDS epidemic is expanding and intensifying globally. Worst affected are undoubtedly the poorer regions of the world as combinations of poverty, disease, famine, political and economic instability and weak health infrastructure exacerbate the severe and far-reaching impacts of the epidemic. One of the major reasons for the apparent ineffectiveness of global interventions is historical weaknesses in the health systems of underdeveloped countries, which contribute to bottlenecks in the distribution and utilisation of funds. Strengthening these health systems, although a vital component in addressing the global epidemic, must however be accompanied by mitigation of other determinants as well. These are intrinsically complex and include social and environmental factors, sexual behaviour, issues of human rights and biological factors, all of which contribute to HIV transmission, progression and mortality. An equally important factor is ensuring an equitable balance between prevention and treatment programmes in order to holistically address the challenges presented by the epidemic

The Prehistoric hand pictures at Gargas: attempts at simulation

A number of experimental methods of reconstructing prehistoric hand images like those in the cave of Gargas, France, are described and assessed. The results of experiments using these methods are evaluated from the point of view of the bearing they have on our knowledge about the creation of the original pictures in the cave

Improving three layer neural net convergence

The authors investigate the relationship between three layer feed forward back-propagation nets (using the terminology of Rumelhart et al., see Nature vol.323, p.533 et seq., 1986) and the committee net of (Nilsson, see Learning Machines, McGraw-Hill, 1956), and show that a simple modification to the algorithm of the latter makes them, in respect of their power to classify data sets, equivalent. Two algorithms may, however, be equivalent in power but differ greatly in their practicality. In the second part the authors conduct some experiments in order to determine whether the modified committee algorithm can compete with back-propagation in a variety of applications. It is found that the committee algorithm (a) is about ten times as fast in some applications and (b) is much less prone to getting trapped in local minima. The theoretical interest in the paper stems from the ease of analysing the committee algorithm together with the equivalence. The experimental interest is that this method of speeding up back-propagation may be used with other improvements to reduce training times in some application

The experience of becoming a PHD.

The development of the next generation of researchers is a priority if South Africa is to make a significant contribution to the international knowledge economy and establish itself as a force to be reckoned with in international research circles. In the context of this knowledge economy, researchers are increasingly being recognised as agents of economic growth. In order to be competitive, therefore, an extensive pool of active researchers needs to be cultivated. One way of doing this is to promote and develop doctoral capacity at the country’s universities. This entails, among other things, a move away from the traditional focus on what the supervisor does, to a more student-centred understanding of how the doctoral candidate experiences the process, and by implication, how this impacts on their research contribution. In this qualitative study, thirty doctoral candidates from the Faculties of Science and Humanities at the University of the Witwatersrand, Johannesburg, were interviewed in order to establish firstly, how they had experienced their supervision at this level, and secondly, whether or not these experiences had influenced the successful completion of their doctorates. One of the principal findings of the research was that the role of the supervisor was not central to the achievement of their degree; rather, many of the doctoral candidates asserted a significant level of agency in both identifying and making contact with experts beyond their university-appointed supervisors in order to supplement their access to relevant knowledge. In the majority of cases, this was encouraged by the supervisors. Such enterprises represent a marked departure from the traditional models of supervision in the Science and Humanities faculties. In the case of the former, the customary co-supervision arrangement is increasingly being augmented by student-initiated collaboration with authorities located outside the formal boundaries of the institution. The traditional Humanities model of supervision is also transforming from a one-on-one relationship to a style characterised by multiple supervisors, each from separate but cognate disciplines. The research suggested that these emergent models are eclipsing their predecessors as doctoral candidates increasingly recognise the value of extending the breadth of their disciplinary exposure beyond the confines of the university

The prospects for developmental local government in the KwaZulu-Natal Midlands.

Thesis (M.Sc.)-University of Natal, 2000.The prospects for the establishment of a system of developmental local government in South Africa appear to be dim. This dissertation examines development delivery in the broader state/market debate. From this debate a clear role is developed for local government as an agent of delivery. This type of local government is characterised by strength and a developmental outlook. An analysis is provided of the history of local government, as well as the legislation and policy that has been out in place to facilitate the transition between apartheid and post-apartheid local government. Through a series of interviews, participant knowledge and data collection, an assessment of the Mooi River TLC is made in terms of its strength and its developmental outlook. The future of local government is found to be constrained by a historical legacy as well as by the actions of groupings inside and outside the local sphere