The University of South Africa is the largest university on the African continent and attracts a third of all higher education students in South Africa. The university has a student headcount of over 300,000 students, including African and international students in 130 countries worldwide, making it one of the world's mega universities.Unisa is a dedicated open distance education institution. Open distance learning entails a student-centred approach that gives students flexibility and choice over what, when, where, and how they learn, and provides them with extensive student support.As a comprehensive university, Unisa offers both vocational and academic programmes, many of which have received international accreditation, as well as an extensive geographical footprint, giving their students recognition and employability in many countries the world over. Wikipedia.
Parawira W.,Kigali Institute of Science and Technology |
Tekere M.,University of South Africa
Critical Reviews in Biotechnology | Year: 2011
One of the major challenges faced in commercial production of lignocellulosic bioethanol is the inhibitory compounds generated during the thermo-chemical pre-treatment step of biomass. These inhibitory compounds are toxic to fermenting micro-organisms. The ethanol yield and productivity obtained during fermentation of lignocellulosic hydrolysates is decreased due to the presence of inhibiting compounds, such as weak acids, furans and phenolic compounds formed or released during thermo-chemical pre-treatment step such as acid and steam explosion. This review describes the application and/or effect of biological detoxification (removal of inhibitors before fermentation) or use of bioreduction capability of fermenting yeasts on the fermentability of the hydrolysates. Inhibition of yeast fermentation by the inhibitor compounds in the lignocellulosic hydrolysates can be reduced by treatment with enzymes such as the lignolytic enzymes, for example, laccase and micro-organisms such as Trichoderma reesei, Coniochaeta ligniaria NRRL30616, Trametes versicolor, Pseudomonas putida Fu1, Candida guilliermondii, and Ureibacillus thermosphaericus. Microbial and enzymatic detoxifications of lignocellulosic hydrolysate are mild and more specific in their action. The efficiency of enzymatic process is quite comparable to other physical and chemical methods. Adaptation of the fermentation yeasts to the lignocellulosic hydrolysate prior to fermentation is suggested as an alternative approach to detoxification. Increases in fermentation rate and ethanol yield by adapted micro-organisms to acid pre-treated lignocellulosic hydrolysates have been reported in some studies. Another approach to alleviate the inhibition problem is to use genetic engineering to introduce increased tolerance by Saccharomyces cerevisiae, for example, by overexpressing genes encoding enzymes for resistance against specific inhibitors and altering co-factor balance. Cloning of the laccase gene followed by heterologous expression in yeasts was shown to provide higher enzyme yields and permit production of laccases with desired properties for detoxification of lignocellulose hydrolysates. A combination of more inhibitor-tolerant yeast strains with efficient feed strategies such as fed-batch will likely improve lignocellulose-to-ethanol process robustness. © 2011 Informa Healthcare USA, Inc.
Sasakura N.,Kyoto University |
Sato Y.,University of South Africa
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2014
Canonical tensor model is a theory of dynamical fuzzy spaces in arbitrary space-time dimensions. Examining its simplest case, we find a connection to a special case of minisuperspace model of general relativity in arbitrary dimensions. This is a first step in interpreting variables in canonical tensor model based on the known language of general relativity. © 2014 The Authors.
Padayachee K.,University of South Africa
Computers and Security | Year: 2012
This paper aims at surveying the extrinsic and intrinsic motivations that influence the propensity toward compliant information security behavior. Information security behavior refers to a set of core information security activities that have to be adhered to by end-users to maintain information security as defined by information security policies. The intention is to classify the research done on compliant information security behavior from an end-user perspective and arrange it as a taxonomy predicated on Self-Determination Theory (SDT). In addition, the relative significance of factors that contribute to compliant information security behavior is evaluated on the basis of empirical studies. The taxonomy will be valuable in providing a comprehensive overview of the factors that influence compliant information security behavior and in identifying areas that require further research. © 2012 Elsevier Ltd. All rights reserved.
Odhiambo N.M.,University of South Africa
Energy Policy | Year: 2010
In this paper we examine the causal relationship between energy consumption and economic growth in three sub-Saharan African countries, namely South Africa, Kenya and Congo (DRC). We incorporate prices as an intermittent variable in a bivariate setting between energy consumption and economic growth-thereby creating a simple trivariate framework. Using the ARDL-bounds testing procedure, we find that the causality between energy consumption and economic growth varies significantly across the countries under study. The results show that for South Africa and Kenya there is a unidirectional causal flow from energy consumption to economic growth. However, for Congo (DRC) it is economic growth that drives energy consumption. These findings have important policy implications insofar as energy conservation policies are concerned. In the case of Congo (DRC), for example, the implementation of energy conservation policies may not significantly affect economic growth because the country's economy is not entirely energy dependent. However, for South Africa and Kenya there is a need for more energy supply augmentations in order to cope with the long-run energy demand. In the short-run, however, the two countries should explore more efficient and cost-effective sources of energy in order to address the energy dependency problem. © 2009 Elsevier Ltd. All rights reserved.
Ziramba E.,University of South Africa
Energy Policy | Year: 2010
This paper examines the demand for imported crude oil in South Africa as a function of real income and the price of crude oil over the period 1980-2006. We carried out the Johansen co integration multivariate analysis to determine the long-run income and price elasticities. A unique long-run cointegration relationship exists between crude oil imports and the explanatory variables. The short-run dynamics are estimated by specifying a general error correction model. The estimated long-run price and income elasticities of -0.147 and 0.429 suggest that import demand for crude oil is price and income inelastic. There is also evidence of unidirectional long-run causality running from real GDP to crude oil imports. © 2010 Elsevier Ltd.