Dynamic Bayesian Networks (DBNs) are temporal probabilistic models for reasoning over time. They often formulate the core reasoning component of intelligent systems in the field of machine learning. Recent studies have focused on the development of some DBNs such as Hidden Markov Models (HMMs) and their variants, which are explicitly represented by highly skilled users and have gained popularity in speech recognition. These varieties of HMMs represented as DBNs have contributed to the baselin...
Abstract In this thesis, we develop the 1 + 1 + 2 formalism, a technique originally devised for General Relativity, to treat spherically symmetric spacetimes in for fourth order theories of gravity. Using this formalism, we derive equations for a static and spherically symmetric spacetime for general f(R) gravity. We apply these master eqautions to derive some exact solutions, which are used to gain insight on Birkhoff's theorem in this framework. Additionally, we derive a covariant form of t...
ABSTRACT Recent demographic dynamics have revealed a dramatic shift in the world’s population, manifesting for the first time ever, more than half of all the world’s population living in urban areas, with 2008 being the transition year. Ghana is not an exception, as its urban centres continue to experience unprecedented growth. Although cities are focal points for development, they equally potentiate the accumulation of risks if not managed properly. The objective of the study therefore i...
Abstract This study concerns the application of a model-based approach for problem solving and conceptual understanding, in the context of kinematics, relating to the “foundation” component of an introductory physics course designed for students who are academically and scientifically underprepared. A new method for portraying objects in motion, “freeze frame” representation, was introduced. The particular visual conceptual model was employed as a representational bridge for translati...
Abstract This thesis investigates the impacts of the demersal trawl fishery on infaunal, epifaunal and fish assemblages in the southern Benguela upwelling system for the first time. In the absence of representative areas of similar habitat protected from trawling in the southern Benguela region, infaunal and epifaunal assemblages were compared between heavily and lightly trawled areas to assess the impacts of the otter-trawl fishery. Infauna were sampled at four sites, from southern Namibia t...
ABSTRACT The occurrence and diversity of bacteria in selected fish culture ponds from three regions in Ghana, Aduabenba Farms, Agyeman Farms, Aheto Farms, Akuse Kpong Farms, ARDEC Station, Asare Farms, Boadi Farm, Boahen Farms, Boateng Farms, Frimpong Farms, K.K. Farms, Pacific Farms and Sagoe Farms and three open systems, Kpong Head Pond, Volta River and Weija Dam were studied over a period of three years, 1996 - 1999. Bacterial populations from the different fish culture systems studied con...
ABSTRACT Background: In Ghana, more than 60 % of under 6 year old children are estimated to suffer from sub-clinical vitamin A deficiency. Bio-fortification is the process of breeding nutrients into crops and it provides a relatively economical, sustainable way of giving out more micronutrients. Cassava is also the leading crop in terms of energy intake and per capita consumption in Ghana thus bio-fortifying cassava with provitamin A can improve the vitamin A composition of this staple food a...
ABSTRACT Rocks and soil covering approximately 81km2 in the Ntunkumso area in the Ashanti Region of Ghana were investigated in the present study. Petrographic studies of eighteen (18) rock samples collected suggest that the rocks are predominantly biotite schist, diorite, granodiorite, and granite. The biotite schist outcrops between Ntunkumso and Boiya and is made up of biotite, quartz, feldspar, iron oxides and opaque minerals. Diorite was encountered at Abesewase and Ofoase and is mineralo...
ABSTRACT This investigation examined petroleum ether, acetone/chloroform, and ethanol extracts of the whole stem of Dichapetalum madagascariense Poir. The petroleum ether extract afforded epifriedelanol (friedelan-3β-ol) together with two mixtures- friedelan-3-one and friedelan-3β-ol; and β-sitosterol and stigmasterol. The acetone/chloroform extract (obtained by combining the acetone and chloroform extracts) afforded friedelin (friedelan-3-one) and β-sitosterol but showed dichapetalin A o...
ABSTRACT The continual emergence of drug resistant strains of Mycobacterium tuberculosis has caused global public health concerns. This project establishes basis for deciphering diverse resistance mechanisms in mycobacteria which would lead to the development of novel therapeutic options. Unique classes of antipsychotic compounds have been found to possess antifungal and anti-mycobacterial activities. The study sought to use antipsychotic compounds and a panel of phenotype modifying compounds...
ABSTRACT Studies have been carried out at Nguruman, south-western Kenya, on Glossina longipennis Corti, a little known member of the fusca group of Glossina. The first objective was to develop an efficient trap suitable for both sampling and control purposes. Studies were then carried out on the population dynamics of G. 1ongipennis using the newly developed sampling methods. Lastly the trap/odour bait system was tested in a control situation. Replicated Latin square design experiments were u...
ABSTRACT Significant effort has been put into the development of cost-effective abalone (Haliotis midae; Gastropoda) cultivation systems in South Africa, but the limited availability of suitable seaweed for abalone food is an obstacle to future development. The aim of this study was to investigate whether a land-based recirculating seaweed-abalone integrated aquaculture system using Ulva lactuca was feasible as well as to test the differences between a commercial gravel bed recirculation syst...
ABSTRACT A new liquid scintillation counting technique to resolve mixtures of two pure beta-emitting radionuclides Winifred Margaret van Wyngaardt Submitted November 2007 Methods currently available for the accurate activity resolution of dual-label solutions of pure β-emitting radionuclides are mostly time consuming and involve much effort. The goal of this thesis was therefore to devise a simpler method to achieve the same objective. The technique developed is based on elements of two liqu...
ABSTRACT Survival analysis is a method for analysing the occurrence of a given event. This research seeks to evaluate the survival of HIVIAIDS, TB and co-infected patients and to identify the major prognostic factors that influence their survival. In this study, survival data for HIV/AIDS, TB and HIVITB co infection patients were obtained from St. Mathias Hospital in Yeji, Pru District of Brong Ahafo Region of Ghana. The data was fitted using both the Cox model and accelerated failure time mo...
Toxicity of ammonia, which can reach toxic levels in aquaculture systems, was investigated for Haliotis midae. Toxic FAN (free un-ionized ammonia) was estimated from TAN (total ammonia nitrogen) measurements. It was found that commonly used Nesslers and Palintest methods underestimated TAN. Tolerance of H midae to ammonia increased with increasing size, as indicated by 36 h LC50 values; farmed juvenile abalone (1 - 2.5 cm shell length) had the smallest LC50 of 9.8 f,lg rl FAN, whereas LC50 wa...