The impact of political and economic events on the asset pricing model described by the arbitrage pricing theory (APTM) was examined in order to establish if they had caused any changes in its specification. It was concluded that the APTM is not stationary and that it must be continuously tested before it can be used as political and economic events can change its specification. It was also found that political events had a more direct effect on the specification of the APTM, in that their effect is more immediate, than did economic events, which influenced the APTM by first influencing the economic environment in which it operated. The conventional approach that would have evaluated important political and economic events, case by case, to determine whether they affected the linear factor model (LFM), and subsequently the APTM, could not be used since no correlation was found between the pricing of a risk factor in the LFM and its subsequent pricing in the APTM. A new approach was then followed in which a correlation with a political or economic event was sought whenever a change was detected in the specification of the APTM. This was achieved by first finding the best subset LFM, chosen for producing the highest adjusted R2 , month by month, over 87 periods from 20 October1991 to 21 June 1998, using a combination of nine prespecified risk factors (five of which were proxies for economic events and one for political events). Multivariate analysis techniques were then used to establish which risk factors were priced most often during the three equal subperiods into which the 87 periods were broken up. Using the above methodology, the researcher was able to conclude that political events changed the specification of the APTM in late 1991. After the national elections in April 1994 it was found that the acceptance of South Africa into the world economic community had again changed the specification of the APTM and the two most important factors were proxies for economic events. / Business Leadership / DBL

Hypertension is a chronic non-communicable disease and a major risk factor for cardiovascular diseases, renal malfunction, disability, and premature death. One of the public health recommendations for the management of hypertension is the reduction of sodium/salt intake. There is need to develop and implement new evidence-based theoretical interventions to initiate and sustain behavior change in health education and promotion. Therefore, the quantitative cross-sectional method and design was used to investigate the adequacy of multi-theory model (MTM) constructs for the initiation and the sustenance of low sodium/salt intake behavior in hypertensive Nigerian adults. In addition, the impact of the MTM (initiation) constructs on actual salt/sodium intake was evaluated to validate self-reported behavior. A convenience sample of 149 consenting Nigerian adults with hypertension and of ages 20 to 60 years, self -administered the valid and reliable 39-item MTM instrument. The findings of confirmatory factor analysis showed construct validity of subscales for the initiation and sustenance model. All items loading for the two models were significant, p < 0.001. Multivariate regression analysis revealed 40.6% of the variance in initiating the consumption of low salt diets explained by advantages outweighing disadvantages, behavioral confidence, and changes in physical environment. About 41.8 % of the variance to sustain the intake of low salt diet was explained by emotional transformation, practice for change, and changes in social environment. The results justified the predictive role of MTM and adequacy of its utility to build evidence-based health education programs and interventions to address the health need of people with hypertension and contribute to social change in the country.

The impact of political and economic events on the asset pricing model described by the arbitrage pricing theory (APTM) was examined in order to establish if they had caused any changes in its specification. It was concluded that the APTM is not stationary and that it must be continuously tested before it can be used as political and economic events can change its specification. It was also found that political events had a more direct effect on the specification of the APTM, in that their effect is more immediate, than did economic events, which influenced the APTM by first influencing the economic environment in which it operated. The conventional approach that would have evaluated important political and economic events, case by case, to determine whether they affected the linear factor model (LFM), and subsequently the APTM, could not be used since no correlation was found between the pricing of a risk factor in the LFM and its subsequent pricing in the APTM. A new approach was then followed in which a correlation with a political or economic event was sought whenever a change was detected in the specification of the APTM. This was achieved by first finding the best subset LFM, chosen for producing the highest adjusted R2 , month by month, over 87 periods from 20 October1991 to 21 June 1998, using a combination of nine prespecified risk factors (five of which were proxies for economic events and one for political events). Multivariate analysis techniques were then used to establish which risk factors were priced most often during the three equal subperiods into which the 87 periods were broken up. Using the above methodology, the researcher was able to conclude that political events changed the specification of the APTM in late 1991. After the national elections in April 1994 it was found that the acceptance of South Africa into the world economic community had again changed the specification of the APTM and the two most important factors were proxies for economic events. / Business Leadership / DBL

Firm real time system with Poisson arrival process, iid exponential service times and iid deadlines till the end of service of a job, operated under the First Come First Served (FCFS) scheduling policy is well studied. In this thesis, we present an exact theoretical analysis of a similar (M/M/1 + G queue) system with exact admission control (EAC). We provide an explicit expression for the steady state workload distribution. We use this solution to derive explicit expressions for the loss ratio and the sojourn time distribution. An exact theoretical analysis of the performance of an M/M/1 + G queue with preemptive deadlines till the end of service, operating under the Earliest Deadline First (EDF) scheduling policy, appears to be difficult, and only approximate formulas for the loss ratio are available in the literature. We present in this thesis similar approximate formulas for the loss ratio in the present of an exit control mechanism, which discards a job at the epoch of its getting the server if there is no chance of completing it. We refer to this exit control mechanism as the Early job Discarding Technique (EDT). Monte Carlo simulations of performance indicate that the maximum approximation error is reasonably small for a wide range of arrival rates and mean deadlines. Finally, we compare the loss ratios of the First Come First Served and the Earliest Deadline First scheduling policies with or without admission or exit control mechanism, as well as their counterparts with deterministic deadlines. The results include some formal equalities, inequalities and some counter-examples to establish non-existence of an order. A few relations involving loss ratios are posed as conjectures, and simulation results in support of these are reported. These results lead to a complete picture of dominance and non-dominance relations between pairs of scheduling policies, in terms of loss ratios.

Multimedia is a form of communication and sharing knowledge using synergic effect of parallel connected communication channels. Its main use is in producing communications products and services and in design of user interfaces. Main objective of this dissertation is to develop and create a model of multimedia communication for better understanding of the meaning and the purpose of using multimedia forms in communication process. The model will describe a system of elements and parameters of multimedia communication within the internal and external context. Another objective of this dissertation is to develop multimedia communication methodology that will be used for the design, development and evaluations of concepts of multimedia communication. The methodology will be created by applying the model of multimedia communication into the procedure structure. In theoretical way this dissertation is based on analysis of different definitions and approaches to the multimedia communications topic. This is followed by an analysis of communication theories, concepts of media, multimedia, delivery channels, and communication functions. The theoretical part is followed by the outcomes of the research in practice of four different fields of multimedia use. The knowledge gained is analyzed in the following parts in purpose of creating the model of multimedia communication and the methodology which is derived from the model. The methodology is further validated through case studies and the recommendations for further development are formulated. The model and the methodology of multimedia communication created in this dissertation present complex view on multimedia communication topic that is considered as a useful tool for meeting a specific communication purpose. Dissertation provides mechanics for use and study of multimedia communication and also defines the opportunities for further development of the methodology.

This study investigated the management of information and communication technologies (ICTs) at academic libraries in selected public universities in Ghana. The purpose for this study was to investigate the managerial processes and challenges in terms of conceptualization, policies, planning, implementation and strategies involved in ICTs adoption in order to formulate strategies for their management in Ghanaian academic libraries. Specifically, the objectives of the study were to review and explore the status and level of ICT diffusion in Ghanaian university; audit the procedures, processes and factors that influence ICT adoption and implementation in Ghanaian university libraries; establish the institutional policies, strategies and human resource that is in place and available for the adoption; determine the factors that hinder the adoption and management of ICTs in Ghanaian university libraries; and design a framework for effective and efficient management of ICTs in Ghanaian public university libraries. The study adopted mixed-method research design approach combining both quantitative and qualitative approaches through the pragmatic worldview to achieve the main purpose of the study. Adopting a survey study design, data was collected from five selected Ghanaian public universities by interviewing the five university librarians/directors, using questionnaires on 313 library staff and making observations within the five libraries. The findings of the study established that the managerial tools/instruments required for effective ICTs management in Ghanaian university libraries include the availability of library ICT policies, a library ICT strategic plan, library ICT installation and maintenance manuals, library ICT integration plans, and standard operations manuals. In addition, adequate funds, skilled manpower, adequate and standard ICT infrastructures among others. However, the study also revealed that there are absence of library ICT policies, lack of processes and procedure guidelines, inadequate funds, lack of management support, inadequate ICT skills among libraries and staff ICT training policies in the academic libraries in Ghana. The study recommends the formulation of ICT policies and strategic plans purposely for the comprehensive management of library ICT systems. Furthermore, the university top management should support their libraries by providing the required resources and motivation for the library managers including the development of stakeholder partnership and collaboration. To galvanise these recommendations, the study proposes a framework for the ICTs adoption and management in Ghanaian university libraries. / Information Science / D. Litt. et Phil. (Information Science)