An ion imprinted polymer for the determination of Ni (II) ions from mine tailing samples
- Authors: Rammika, Modise
- Date: 2011
- Subjects: Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4323 , http://hdl.handle.net/10962/d1004981 , Imprinted polymers , Metal ions , Polymerization , Mineral industries -- Waste disposal
- Description: A Ni(II)-dimethylglyoxime ion imprinted polymer {Ni(II)-DMG IIP} was synthesized by the trapping method using the bulk polymerisation format. The structures of the imprinted and non-imprinted polymer were evaluated by infrared spectroscopy and the morphology was observed by scanning electron microscopy. The Ni(II)-DMG IIP was optimised for pH, mass, time and by the uniform design experimental method for the molar ratios of monomer to crosslinker to porogen and template to ligands as well as keeping these parameters constant and varying the quantities of initiator, 2,2'-azobisisobutyronitrile (AIBN). The optimum pH was 8.5, optimum mass was 50 mg, optimum time was 1 min and the optimum molar ratios of crosslinker to monomer, monomer to template and nickel(II) sulfate hexahydrate (NiSO₄.6H₂O) to 4-vinylpyridine to dimethylglyoxime were found to be 3.3:1.0, 0.6:1.0 and 1.0:0.6:3.6 respectively with 30 mg and 8 mL as the optimum amounts of initiator and porogen respectively. Through this optimisation, recovery of Ni(II) was increased from 98 to 100%. Selectivity of the ion imprinted polymer was evaluated by analysing, using an inductively coupled plasma-optical emission spectrometer, for Ni(II) ions that were spiked with varying concentrations of Co(II), Cu(II), Zn(II), Pd(II), Fe(II), Ca(II), Mg(II), Na(I) and K(I) in aqueous samples. Selectivity studies also confirmed that the ion imprinted polymer had very good selectivity characterised by % RSD of less than 5 %. Co(II) was the only ion found to slightly interfere with the determination of Ni(II). The limits of detection and quantification were found to be 3x10⁻⁴ μg/mL and 9x10⁻⁴ μg/mL respectively. The method was evaluated by a custom solution of ground water certified reference material (SEP-3) and sandy soil reference material (BCR-142R) and the concentrations of Ni(II) obtained were not significantly different to the certified ones. The Ni(II)-DMG IIP was then evaluated in aqueous and soil samples where recoveries of 93 to 100% and 98 to 99% respectively were obtained with enrichment factors ranging from 2 to 18 in aqueous and 27 to 40 in soil samples. Finally, the Ni(II)-DMG IIP was used to analyse mine tailings samples and Ni(II) recovery of 99% was obtained with an enrichment factor of 2.
- Full Text:
An organisation development intervention in a secondary school in the Erongo region of Namibia
- Authors: Steenkamp, Angeline Anna
- Date: 2011
- Subjects: School management and organization -- Namibia -- Erongo Organizational change -- Namibia -- Erongo Curriculum planning -- Namibia -- Erongo
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1683 , http://hdl.handle.net/10962/d1003566
- Description: The challenge for Namibia is to translate Vision 2030 into realistic and implementable programmes and to develop and adopt a set of interventions which will raise the quality of education. The quality of education currently on offer varies from school to school and, indeed, from class to class (Namibia. MoE, 2006, p. 1). The National Standards and Performance Indicators (ETSIP, 2006) for schools in Namibia and the Education and Training Sector Improvement Programme (ETSIP), have been developed to address the quality of education across the country, and to make provision for school managers to be trained. Organisation Development is a planned change approach which focuses on the change processes of the organisation, by opening up communication, decreasing internal destructiveness – such as win-lose conflicts – and by increasing creativity in problem solving. It is based on the values and assumptions about people and their organisations. OD promotes interdependence and interconnectedness, involvement in problem solving and decision making. OD is a process for teaching people how to solve problems, take advantage of opportunities, and learn how to do better over time. OD was introduced to Evergreen Senior Secondary School in the form of a Survey Data Feedback (SDF) where data was collected, analysed and fed back to the participants. The case study involved 20 staff members made up of the principal, two head of departments and 17 teachers. Formal and focus-group interviews, as well as observation, were used to collect data. What was derived from the data was that the OD approach was something new to the participants, and served as an eye-opener. Further, it became evident from the data that participants had high hopes that OD would bring about immediate visible changes regarding the operation of their organisation. It is essential to remind participants that OD is a long-term change process, and not a “quick fix”.
- Full Text:
Analysis of volatility spillover effects between the South African, regional and world equity markets
- Authors: Mumba, Mabvuto
- Date: 2011
- Subjects: Financial crises International finance Stocks -- Prices -- Africa Stocks -- Prices -- South Africa Capital market -- Africa Capital market -- South Africa Foreign exchange rates Africa -- Economic conditions South Africa -- Economic conditions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:957 , http://hdl.handle.net/10962/d1002691
- Description: The current study examines the extent and magnitude by which global and regional shocks are transmitted to the volatility of returns in the stock markets of South Africa, Egypt, Nigeria, Botswana, Mauritius and Egypt. This is done so as to make inferences on the level of the domestic market‟s integration into the regional and world capital markets. By applying multivariate and univariate GARCH models, using weekly data from June 1995 to May 2010, the main empirical findings are threefold. Firstly, the volatility analytical framework finds statistically significant and time-varying volatility spillover effects from the regional and global markets to the South African market. Global shocks are generally stronger and account for up to 23.9 percent of the volatility of South Africa‟s equity market compared to weaker regional factors which account for less than 1 percent of domestic variance. Only in countries with strong bilateral trade and economic links with South Africa, such as Botswana and Namibia, is it found that regional factors are more dominant than global factors for domestic volatility. Compared to the other African markets, the joint influence of foreign shocks on domestic volatility is highest in South Africa and Egypt, two of Africa‟s largest and most developed markets. The results further demonstrate that for all the African markets the explanatory power of both regional and global factors for domestic volatility is not constant over time and tends to increase during turbulent market periods. Secondly, the analysis of the determinants of South frica‟s second moment linkages with the global market suggests that the volatility of the exchange rate plays a cardinal role in influencing the magnitude by which global shocks affect domestic volatility. The increased global integration in the second moments cannot be attributed to either increased trade integration, convergence in inflation rates or to convergence in interest rates between South Africa and the global markets. Lastly, tests were conducted to examine whether there have been contagion effects from the regional and global markets to South Africa from the 1997 Asian crisis and the 2007/8 global financial crisis. The results show no evidence of contagion during either the East Asian currency crisis or the recent global financial crisis to South Africa, while some African markets, such as Egypt, Mauritius and Botswana, exhibit contagion effects from either crisis. Overall, the empirical findings generally support the view that African markets are segmented both at the regional and global levels as domestic volatility is more influenced by local idiosyncratic shocks (the proportion not attributable to either global and regional factors). However, the volatility of South Africa, and to a lesser extent Egypt, remains relatively more open to global influence. This implies that the potential for gains from international portfolio diversification and the scope for success of policies aimed at the stabilisation of equity markets in these markets exist.
- Full Text:
Angel networks as a business start-up financing option in South Africa
- Authors: Sibanda, Zenzo
- Date: 2011
- Subjects: Angels (Investors) -- South Africa Small business -- Finance -- South Africa New business enterprises -- Finance -- South Africa Venture capital -- South Africa Microfinance -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1164 , http://hdl.handle.net/10962/d1002780
- Description: The following study is about business angels financing small business start-ups. It explores the aspect of starting up an entrepreneurial venture in which the entrepreneur seeks to secure start-up finance from lenders, raising the various issues that are known to characterise this engagement between the entrepreneur and the lender. Using the phenomenological paradigm, the study seeks to determine the awareness of small scale financing by entrepreneurs in South Africa, to determine the most commonly used source of start-up business funding in South Africa, to assess the extent to which business angel financing could be used to finance businesses in South Africa and to determine the factors impacting the use of business angel financing in South Africa. From these objectives, the study will also seek to determine the extent to which business angel networks could facilitate the financing of business start-ups. Small businesses invariably come up in different policy spheres as the main avenues to social and economic construction across national and regional lines. The importance of a successful business start up to a growing economy should not be underestimated. In line with this is the particular factor of gaining access to start up capital, which continues to emerge as a leading contributor to the success or failure of business start ups. Studies continue to verify that the most common challenge faced by most emerging entrepreneurs is start-up capital, either in the lack of this capital, the unfavourable conditions surrounding its availability, the lack of assets to serve as collateral for its use or the ambiguous flow of crucial information between lenders and providers of finance in the funding relationship (Abor and Biekpe, 2006: 69;Hernandez-Trillo, Pagan and Paxton, 2005: 435, ISPESE, 2005: 7, CDE, 2004: 5; Musengi 2003: 11). Roger Sorheim (2005: 179) refers to business angels as private individuals who offer risk capital to unlisted companies that are struggling to obtain start up capital to finance their business ideas. Business angels are further defined as high net-worth bearers of substantial private capital who predominantly invest in the early stage of high risk high potential return business ventures with a positive further growth potential. Business angel finance is typically a ‘once-off’ early stage form of small firm financing compared to the more frequent later stage venture capitalist funding. Studies show that business angels represent an underutilised wealth creation mechanism when it comes to small firm start-ups as most business angels contribute expertise in addition to finance to the start-ups they get involved in. This brings valuable business insight to the commercialisation of a good business idea. The business angel network exposes a range of potentially viable business prospects to willing investors by facilitating the flow of information about entrepreneurs and their businesses, thereby eliminating ambiguity, information asymmetry and transaction costs (Aernoudt and Erikson, 2002: 178; Van Osnabrugge and Robinson, 2000:374; Macht, 2006:1; Ehlrich, De Noble, Moore and Weaver, 1994:70; Sorheim, 2005:179). To achieve a holistic approach to a phenomenon which appears to be relatively new in South African business circles, the study will follow a qualitative approach in which two categories of populations will be used, one of small business operators and the other of business angels in South Africa. In the study, 20 small business operators and five business angels in Grahamstown will be approached using the convenience and snowballing sampling methods respectively. Face-to-face semi-structured interviews will be used as a data collection method and content analysis will be used as a data analysis tool (Collis and Hussey, 2003:156, Driver, Wood, Segal and Herrington, 2001:32, National Small Business Act ). There has been very limited research on business angels in the South African context, therefore the study would significantly contribute in entrepreneurship, government and small business development circles as it brings about attention to what the researcher predicts is an underutilised business start-up financing option.
- Full Text:
Application of catalysts and nanomaterials in the design of an electrochemical sensor for ochratoxin A
- Authors: Flanagan, Shane Patrick
- Date: 2011 , 2010-12-06
- Subjects: Ochratoxins , Filamentous fungi , Electrochemical sensors , Nanostructured materials , Catalysts , Food contamination
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4121 , http://hdl.handle.net/10962/d1013328
- Description: Ochratoxin A is the most potent chlorinated derivative of the ochratoxin group, consisting of a 5'-chlorinated dihydroisocoumarin moiety linked by an amide bond to l-phenylalanine. Produced as a secondary fungal metabolite by several species of Aspergillus and Penicillium, ochratoxin A has been shown to readily contaminate a large variety of commodities including cereals, groundnuts, dried fruit, spices and coffee. This has led to widespread contamination of ochratoxin in wine, beer, milk and meat products. As ochratoxin A is a potent nephrotoxin exhibiting teratogenic and carcinogenic properties, the development of a rapid screening platform for the cost effective control of ochratoxin A content in foodstuffs is therefore required. The evaluation of metallophthalocyanine and carbon nanotube electrode modification toward the development of a nanostructured biosensor capable of enhancing the electrochemical detection of ochratoxin A in complex media is presented. Cyclic voltammetry at a glassy carbon electrode allowed for the optimization of detection parameters including pH and type of supporting electrolyte. Britton-Robinson buffer was found to be the most suitable supporting electrolyte in terms of sensitivity and reproducibility obtaining a LOD of 0.28 μM as determined by differential pulse voltammetry. Subsequent analysis determined the dependence of OTA oxidation on pH in acidic media which proceeds with the transfer of two electrons to form a quinone/hydroquinone couple shown to adsorb to the electrode surface. Passivation of the electrode through adsorption of oxidation products was shown to severely limit the detection of OTA upon successive detection cycles. Comparison of various metallophthalocyanine modifiers showed an increase in sensitivity toward the detection of OTA at phthalocyanine complexes with metal based redox processes. However with the exception of NiPc and CoTCPc complexes, phthalocyanine modification was limited by the increase in deviation of current response and extent of fouling. NiPc modification showed an increase in sensitivity by two fold with fouling characteristics comparable to an unmodified electrode while low improvements in fouling was observed at CoTCPc modified electrodes with sensitivity in detection comparable to an unmodified electrode.Modification of the electrode with multi- and single walled carbon nanotubes produced a significant increase in sensitivity toward the detection of ochratoxin A. The electrocatalytic activity of nanotube modifiers was attributed to the increase in surface area and to the addition of oxygenated functional groups upon acid treatment as confirmed by Raman spectroscopy. Acid functionalization of the carbon nanotubes for a period of two hours produced the greatest increase in sensitivity obtaining a respective LOD of 0.09 μM and 0.03 μM for analysis of ochratoxin A at multi- and single walled carbon nanotube modified electrodes. Centrifugal purification of carbon nanotubes was deemed necessary to improve the electrocatalytic activity of the nanotube modifiers through the removal of carbonaceous impurities as visualized by atomic force microscopy. Furthermore, a crude lipase preparation, lipase A, was investigated as a potential biological recognition element for selective detection of ochratoxin A in complex media. Lipase A enabled the hydrolysis of ochratoxin A to the electroactive species ochratoxin α as confirmed by thin layer chromatography and voltammetric analysis. Additional isolation of a pure hydrolase from the lipase A preparation is required prior to utilization within a nanostructured biosensor platform capable of detecting ochratoxin A in complex media.
- Full Text:
Application of macroinvertebrate based biomonitoring approaches to assess anthropogenic impacts in the Swartkops River, South Africa
- Authors: Odume, Oghenekaro Nelson
- Date: 2011
- Subjects: Water -- Pollution -- South Africa -- Swartkops River Water quality biological assessment -- South Africa -- Swartkops River Environmental monitoring -- South Africa -- Swartkops River Aquatic invertebrates -- Effect of water pollution on -- South Africa -- Swartkops River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6040 , http://hdl.handle.net/10962/d1006199
- Description: A growing human population accompanied by urbanisation and industrialisation have led to over exploitation and pollution of freshwater resources and have consequently impacted on aquatic ecosystem health. The Swartkops River in the Eastern Cape of South Africa is no exception. It drains a heavily industrialised catchment which has led to deterioration of its water quality due to pollution. Integrated water resources management (IWRM) requires the concurrent sustainable use of water resources and the protection of aquatic ecosystem health. Macroinvertebrates are well known for their ability to reflect the health of the environment in which they live, thus they were used to assess anthropogenic impacts in the Swartkops River for this study. Macroinvertebrate based biomonitoring approaches, including the South African Scoring System version 5 (SASS5); a multimetric approach involving 19 metrics; Chironomidae community assessments and screening of morphological deformities in Chironomidae larvae, were applied at four selected sampling sites to assess environmental water quality in the Swartkops River. Macroinvertebrates were sampled us ing the SASS5 protocols. Chironomidae were mounted and identified as far as practically possible using available keys. Mentum, ligula, mandible, paraligula and antenna in Chironomidae larvae were screened for deformities. Physical and chemical water quality variables were measured at each of the selected sampling sites. All data were subjected to relevant statistical analyses. Of the four sites sampled during the study period, results revealed that water quality at site 1 was the least impacted with highest SASS5 scores, average score per taxa (ASPT) values, richness, diversity, equitability and Ephemeroptera –Plecoptera-Trichoptera (EPT) richness, as well as least incidences of chironomid deformities. Water quality at site 2 was considered the next least impacted with higher SASS5 scores, A SPT values, richness, diversity and equitability, and lower incidences of deformities compared to sites 3 and 4. SASS5 scores and ASPT values revealed that both sites 3 and 4 were critically modified but the multimetric analysis, Chironomidae community assessment and incidences of deformities in Chironomidae larvae indicated that site 3 is the most impacted of the four sampling sites, with least species diversity, richness, equitability and highest incidences of deformities. The study revealed the importance of multicriteria approach to environmental biomonitoring as an integrated water resources management tool, and based on the results, site 3, as the most impacted, could be prioritised for restoration intervention.
- Full Text:
Assessment of organochlorine pesticide residues in fish samples from the Okavango Delta, Botswana
- Authors: Mpofu, Christopher
- Date: 2011 , 2011-02-28
- Subjects: Pesticides , Organochlorine compounds , Freshwater fishes -- Effect of pesticides on -- Botswana -- Okavango River Delta , Water -- Pesticide content -- Botswana -- Okavango River Delta , Catfishes -- Botswana -- Okavango River Delta , Tigerfish -- Botswana -- Okavango River Delta , Redbreast tilapia -- Botswana -- Okavango River Delta
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4404 , http://hdl.handle.net/10962/d1006707 , Pesticides , Organochlorine compounds , Freshwater fishes -- Effect of pesticides on -- Botswana -- Okavango River Delta , Water -- Pesticide content -- Botswana -- Okavango River Delta , Catfishes -- Botswana -- Okavango River Delta , Tigerfish -- Botswana -- Okavango River Delta , Redbreast tilapia -- Botswana -- Okavango River Delta
- Description: This thesis presents an evaluation of the dispersive solid-phase extraction (d-SPE) method referred to as the quick, easy, cheap, effective, rugged and safe (QuEChERS) method for the determination of four organochlorine pesticide residues in fish samples. The pesticides investigated in this study were o, p′-DDT, p, p′-DDE, aldrin and dieldrin. The combined use of Gas Chromatography with an Electron Capture Detector (GC-ECD) and sensitive Time of Flight (TOF) mass detector facilitated the identification of the target analytes. In the absence of certified reference material, the overall analytical procedure was validated by systematic recovery experiments on spiked samples at three levels of 2, 5 and 10 ng/g. The targeted compounds were successfully extracted and their recovery ranged from 76 to 96% with relative standard deviations of less than 13%. The optimum QuEChERS conditions were 2g of fish powder, 10 ml acetonitrile and 1 min shaking time. The optimal conditions were applied to assess the levels of chlorinated pesticides in blunt-tooth catfish (Clarias ngamensis), tigerfish (Hydrocynus vittatus), Oreochromis andersonii and red-breasted tilapia (Tilapia rendalli) from the Okavango Delta, Botswana. Dieldrin, p, p′-DDE and aldrin were detected in all the analysed samples with a concentration range of 0.04 – 0.29, 0.07 – 0.33, 0.04 – 0.28 and 0.03 – 0.24 ng/g per dry weight in O. andersonii, C. ngamensis, T. rendalli and H. vittatus respectively. These concentrations were below the US-EPA 0.1 μg/g allowable limit in edible fish and the Australian Maximum Residue Limit (MRL) of 50 - 1000 ng/g in fresh fish. DDT was not detected in all the fish species investigated. The mean lipid content recorded in the fish samples were 1.24, 2.16, 2.18 and 4.21% for H. vittatus, T. rendalli, O. andersonni and C. ngamensis respectively. No systematic trend was observed between fish age and pesticide levels in fish. Acetylcholinesterase (AChE) activity assays were performed to assess the effects of organochlorine pesticides in Clarias ngamensis. The enzyme activity recorded in Clarias ngamensis from the Okavango Delta and the reference site was 12.31 μmol of acetylcholine iodide hydrolysed/min/g brain tissue. The enzyme activity remained the same indicating no enzyme inhibition. The conclusions drawn from this study are that the QuEChERS method is applicable for the determination of organochlorine pesticide residues in fish matrices. The fish from the Okavango Delta are safe for human consumption.
- Full Text:
Bayesian logistic regression models for credit scoring
- Authors: Webster, Gregg
- Date: 2011
- Subjects: Bayesian statistical decision theory Credit scoring systems Regression analysis Logistic regression analysis Monte Carlo method Markov processes Financial institutions
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:5574 , http://hdl.handle.net/10962/d1005538
- Description: The Bayesian approach to logistic regression modelling for credit scoring is useful when there are data quantity issues. Data quantity issues might occur when a bank is opening in a new location or there is change in the scoring procedure. Making use of prior information (available from the coefficients estimated on other data sets, or expert knowledge about the coefficients) a Bayesian approach is proposed to improve the credit scoring models. To achieve this, a data set is split into two sets, “old” data and “new” data. Priors are obtained from a model fitted on the “old” data. This model is assumed to be a scoring model used by a financial institution in the current location. The financial institution is then assumed to expand into a new economic location where there is limited data. The priors from the model on the “old” data are then combined in a Bayesian model with the “new” data to obtain a model which represents all the available information. The predictive performance of this Bayesian model is compared to a model which does not make use of any prior information. It is found that the use of relevant prior information improves the predictive performance when the size of the “new” data is small. As the size of the “new” data increases, the importance of including prior information decreases
- Full Text:
Being Indian, being MK: an exploration of the experiences and ethnic identities of Indian South African Umkhonto we Sizwe members
- Authors: Lalla, Varsha
- Date: 2011
- Subjects: Umkhonto we Sizwe (South Africa) -- Research Political activists -- Research -- South Africa East Indians -- Politics and government -- Research -- South Africa Ethnicity -- Political aspects -- South Africa -- Research
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2792 , http://hdl.handle.net/10962/d1003002
- Description: Umkhonto we Sizwe (MK) was a military organization dominated by black Africans. Although it is not generally associated with Indian South Africans, who form a minority in the country, there were Indian MK members. This thesis explores the way in which Indian MK members reconciled aspects of their ethnic identity with their membership of MK. It explores the experiences of two generations of members: those born between 1929 and 1944 and those born between 1960 and 1969. In particular it looks at whether they experienced tensions between their ethnic and political identities. It explores what set these Indian South Africans apart from the rest of the Indian South African community that did not join MK. It also looks at what significant differences there were between different generations of Indian MK members. The research results show that the first generation MK members believe that their MK activities were „the highest form of passive resistance‟. An explanation for this way of referring to their activities could be that this was a way of reconciling tensions between their ethnic and political identities. The first generation was also very critical of the Indian SA community. This could be because they still feel part of this community despite having a strong political consciousness that is different from most of the community. It was found that some of the features that set Indian MK members apart from other Indian South Africans were that they were not raised in very religious households and occupied a fairly low rather than „middle man‟ economic position. In addition, members of the first generation of MK members were raised in comparatively multi-racial areas. Both generations made the decision to join MK because of Indian role models. There were some marked differences between the two generations of MK veterans. Most notably, the younger did not see their activities as in line with passive resistance and they also displayed more ambivalence about their ethnic identities.
- Full Text:
Biomechanical, physiological and perceptual responses of three different athlete groups to the cycle-run transition
- Authors: Cripwell, Devin Matthew
- Date: 2011
- Subjects: Biomechanics -- Research , Human mechanics -- Research , Cycling -- Physiological aspects -- Research , Running -- Physiological aspects -- Research , Exercise -- Physiological aspects -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5106 , http://hdl.handle.net/10962/d1005184 , Biomechanics -- Research , Human mechanics -- Research , Cycling -- Physiological aspects -- Research , Running -- Physiological aspects -- Research , Exercise -- Physiological aspects -- Research
- Description: The transition from cycling to running has been identified as one of the key determinants of success in triathlon, as it has been suggested that the cycle may affect subsequent running efficiency such that running performance is significantly altered or reduced. It is also suggested that athletes more adapted to the transition itself, rather than purely running or cycling, may be more efficient during the post-cycle running bout. The current study sought to investigate the effects of prior cycling on subsequent selected biomechanical, physiological and perceptual responses of three different athlete groups. Subjects were selected on the basis of their sporting background, and were divided into three groups – triathletes, cyclists and runners. Experimentation required subjects to perform a seven minute treadmill running protocol at 15km.h⁻¹, during which biomechanical (EMG, Stride rate, Stride length, Vertical acceleration), physiological (HR, VO₂, EE) and perceptual (RPE) responses were recorded. After resting, subjects were required to perform a twenty minute stationary cycle at 70% of maximal aerobic power (previously determined), immediately followed by a second seven minute treadmill running protocol during which the same data were collected and compared to those collected during the first run. Biomechanical responses indicate that the cycle protocol had no effect on the muscle activity or vertical acceleration responses of any of the three subject groups, while the triathlete group significantly altered their gait responses in order to preserve running economy. The triathlete group was the least affected when considering the physiological responses, as running economy was preserved for this group. The runner and cyclist groups were significantly affected by the transition, as running economy decreased significantly for these groups. Perceptual responses indicate that athletes more experienced with the transition may find the transition from cycling to running to be easier than those inexperienced in this transition. It is apparent that a high intensity cycle protocol has limited statistical impact on selected biomechanical responses, while physiological and perceptual responses were altered, during a subsequent run, regardless of athlete type. That said, the ability of transition-trained athletes to transition comfortably between disciplines was highlighted, which may have important performance implications.
- Full Text:
Bluetooth audio and video streaming on the J2ME platform
- Authors: Sahd, Curtis Lee
- Date: 2011 , 2010-09-09
- Subjects: Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4633 , http://hdl.handle.net/10962/d1006521 , Bluetooth technology , Mobile communication systems , Communication -- Technological innovations , Communication -- Network analysis , Wireless communication systems , L2TP (Computer network protocol) , Computer network protocols , Streaming audio , Streaming video
- Description: With the increase in bandwidth, more widespread distribution of media, and increased capability of mobile devices, multimedia streaming has not only become feasible, but more economical in terms of space occupied by the media file and the costs involved in attaining it. Although much attention has been paid to peer to peer media streaming over the Internet using HTTP and RTSP, little research has focussed on the use of the Bluetooth protocol for streaming audio and video between mobile devices. This project investigates the feasibility of Bluetooth as a protocol for audio and video streaming between mobile phones using the J2ME platform, through the analysis of Bluetooth protocols, media formats, optimum packet sizes, and the effects of distance on transfer speed. A comparison was made between RFCOMM and L2CAP to determine which protocol could support the fastest transfer speed between two mobile devices. The L2CAP protocol proved to be the most suitable, providing average transfer rates of 136.17 KBps. Using this protocol a second experiment was undertaken to determine the most suitable media format for streaming in terms of: file size, bandwidth usage, quality, and ease of implementation. Out of the eight media formats investigated, the MP3 format provided the smallest file size, smallest bandwidth usage, best quality and highest ease of implementation. Another experiment was conducted to determine the optimum packet size for transfer between devices. A tradeoff was found between packet size and the quality of the sound file, with highest transfer rates being recorded with the MTU size of 668 bytes (136.58 KBps). The class of Bluetooth transmitter typically used in mobile devices (class 2) is considered a weak signal and is adversely affected by distance. As such, the final investigation that was undertaken was aimed at determining the effects of distance on audio streaming and playback. As can be expected, when devices were situated close to each other, the transfer speeds obtained were higher than when devices were far apart. Readings were taken at varying distances (1-15 metres), with erratic transfer speeds observed from 7 metres onwards. This research showed that audio streaming on the J2ME platform is feasible, however using the currently available class of Bluetooth transmitter, video streaming is not feasible. Video files were only playable once the entire media file had been transferred.
- Full Text:
Characterization of stratified L-topological spaces by convergence of stratified L-filters
- Authors: Orpen, David Lisle
- Date: 2011
- Subjects: Topology , Generalized spaces , Filters (Mathematics) , Topological spaces
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5402 , http://hdl.handle.net/10962/d1005216 , Topology , Generalized spaces , Filters (Mathematics) , Topological spaces
- Description: For the case where L is an ecl-premonoid, we explore various characterizations of SL-topological spaces, in particular characterization in terms of a convergence function lim: FS L(X) ! LX. We find we have to introduce a new axiom , L on the lim function in order to completely describe SL-topological spaces, which is not required in the case where L is a frame. We generalize the classical Kowalski and Fischer axioms to the lattice context and examine their relationship to the convergence axioms. We define the category of stratified L-generalized convergence spaces, as a generalization of the classical convergence spaces and investigate conditions under which it contains the category of stratified L-topological spaces as a reflective subcategory. We investigate some subcategories of the category of stratified L-generalized convergence spaces obtained by generalizing various classical convergence axioms.
- Full Text:
Co-utilisation of microalgae for wastewater treatment and the production of animal feed supplements
- Authors: Johnson, Hailey E
- Date: 2011
- Subjects: Microalgae -- Biotechnology , Algae culture , Algae products , Waste products as feed , Sewage -- Purification , Organic wastes -- Recycling , Food industry and trade -- Waste disposal , Agriculture -- Waste disposal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3940 , http://hdl.handle.net/10962/d1003999 , Microalgae -- Biotechnology , Algae culture , Algae products , Waste products as feed , Sewage -- Purification , Organic wastes -- Recycling , Food industry and trade -- Waste disposal , Agriculture -- Waste disposal
- Description: Microalgae have a variety of commercial applications, the oldest of which include utilisation as a food source and for use in wastewater treatment. These applications, however, are seldom combined due to toxicity concerns, for ethical reasons, and generally the requirement for cultivation of a single algae species for use as a feed supplement. These problems might be negated if a “safer” wastewater such as that from agricultural and/or commercial food production facilities were to be utilised and if a stable algae population can be maintained. In this investigation preliminary studies were carried out using an Integrated Algae Pond System (IAPS) for domestic wastewater treatment to determine the species composition in the associated High Rate Algae Ponds (HRAPs). The effect of different modes of operation, continuous versus batch, on nutrient removal, productivity and species composition was also investigated. Furthermore, indigenous species in the HRAP were isolated and molecularly identified as, Chlorella, Micractinium, Scenedesmus and Pediastrum. Additionally, the effect of the nor amino acid, 2-hydroxy-4-(methylthio)-butanoic acid (HMTBA) and its Cu-chelated derivative, on the growth and biochemical composition of Chlorella, Micractinium, Scenedesmus, Pediastrum and Spirulina was investigated. Species composition in the HRAP was stable under continuous operation with Micractinium dominating > 90% of the algae population. Under batch operation the population dynamic shifted; Chlorella outcompeted Micractinium possibly due to nutrient depletion and selective grazing pressures caused by proliferation of Daphnia. Higher species diversity was observed during batch mode as slower growing algae were able to establish in the HRAP. Nutrient removal efficiency and biomass productivity was higher in continuous mode, however lower nutrient levels were obtained in batch operation. HMTBA did not significantly affect growth rate, however treatment with 10 mg.L-1 resulted in slightly increased growth rate in Micractinium and increased final biomass concentrations in Chlorella, Micractinium and Spirulina (although this was not statistically significant for Micractinium and Spirulina), which are known mixotrophic species. Algae treated with Cu-HMTBA, showed reduced final biomass concentration with 10 mg.L-1, caused by Cu toxicity. Biochemical composition of the algae was species-specific and differed through the growth cycle, with high protein observed during early growth and high carbohydrate during late growth/early stationary phase. Additionally, 0.1 mg.L-1 HMTBA and Cu-HMTBA significantly reduced protein content in Chlorella, Micractinium, Scenedesmus and Pediastrum. In conclusion, operation of the HRAP in continuous culture provided suitable wastewater treatment with high productivity of an ideal species, Micractinium, for use in animal feed supplementation. This species had 40% protein content during growth (higher than the other species tested) and dominated the HRAP at > 90% of the algae population during continuous mode. Addition of HMTBA (> 1 mg.L-1) to algae cultivation systems and those treating wastewater, has the potential to improve productivity and the value of the biomass by enhancing protein content. Overall, the co-utilisation of microalgae for wastewater treatment and the generation of a biomass rich in protein, for incorporation into formulated animal feed supplements, represents a closed ecosystem which conserves nutrients and regenerates a most valuable resource, water.
- Full Text:
Cointegration in equity markets: a comparison between South African and major developed and emerging markets
- Authors: Petrov, Pavel
- Date: 2011
- Subjects: Cointegration Stock exchanges -- South Africa Stock exchanges -- Developing countries Stock exchanges -- Developed countries South Africa -- Economic conditions Portfolio management -- South Africa Econometrics Autoregression (Statistics)
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:5575 , http://hdl.handle.net/10962/d1005539
- Description: Cointegration has important implications for portfolio diversification. One of these is that in order to spread risk it is advisable to invest in markets that are not cointegrated. Over the last several decades communication technology has made the world a smaller place and hence cointegration in equity markets has become more prevalent. The bulk of research into cointegration focuses on developed and Asian markets, with little research been done on African markets. This study compares the Engle-Granger and Johansen tests for cointegration and uses them to calculate the level of cointegration between South African and other global equity markets. Each market is compared pair-wise with South Africa and the results have been that in general South Africa is cointegrated with other emerging markets but not really with African nor developed markets. Short-run analysis with the error correction was carried out and showed that in general markets respond slowly to any disequilibrium. Innovation accounting methods showed that the country placed first in Cholesky ordering dominates the other one. Multivariate cointegration was carried out using three selections of 4, 6 and 8 market portfolios. One of the markets was SA and the others were all chosen based on the criteria that they are not pair-wise cointegrated with SA. The level of cointegration varied depending on the portfolios, as did the error correction rates, impulse responses and variance decomposition. The one constant was that the USA dominated any portfolio where it was introduced. Recommendations were finally made about which market portfolio an investor should consider as most favourable.
- Full Text:
Cointegration, causality and international portfolio diversification : investigating potential benefits to a South African investor
- Authors: Msimanga, Nkululeko Lwazi
- Date: 2011
- Subjects: Cointegration , Econometrics , International finance , Stock exchanges -- South Africa , Stock exchanges -- Developing countries , Stock exchanges -- Developed countries , Investments -- South Africa , Portfolio management -- South Africa , Investment analysis , Autoregression (Statistics)
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:962 , http://hdl.handle.net/10962/d1002696 , Cointegration , Econometrics , International finance , Stock exchanges -- South Africa , Stock exchanges -- Developing countries , Stock exchanges -- Developed countries , Investments -- South Africa , Portfolio management -- South Africa , Investment analysis , Autoregression (Statistics)
- Description: Research studies on portfolio diversification have tended to focus on developed markets and paid less attention to emerging markets. Traditionally, correlation analysis has been used to determine potential benefits from diversification but current studies have shifted focus from correlation analysis to exploring cointegration analysis and other forms of tests such as the Vector Error Correction Methodology. The research seeks to find if it is beneficial for a South African investor to diversify their portfolio of emerging market equities over a long-term period. Daily weighted share indices for the period of January 1996 to November 2008 were collected and analysed through the application of the Johansen cointegration technique and Vector Error Correction Methodology. Granger Causality tests were also performed to established whether one variable can be useful in forecasting another variable. The study found that there was at least one statistically significant long-run relationship between the emerging markets. After testing for unit roots for all the share indices and their first difference using the Augmented Dickey-Fuller test (ADF), Philips-Perron and Kwiatkowski, Phillips, Schmidt, and Shin (KPSS) unit root tests, similar conclusions were m~de. All the unit root tests and their levels could not be rejected for all the series. However, unit root tests on the first differences were rejected, meaning that all series are of order 1(1) - evidence of cointegration. Simply put, emerging markets tend not to drift apart over time. This suggests that emerging markets offer limited benefits to investors who are looking to add some risk to their portfolios. In addition, the study also found evidence of both unidirectional and bidirectional causality (Granger-Cause tests) between markets. This implies that the conditions for a particular market are exogenous of the other market. The study concludes that emerging markets are gradually adopting the same profile as developed markets.
- Full Text:
Community radio and museum outreach: a case study of community radio practices to inform the environment and sustainability programmes of Livingstone Museum
- Authors: Muloongo, Arthanitius Henry
- Date: 2011
- Subjects: Community radio -- Zambia Livingstone Museum Museum outreach programs -- Zambia Environmental education -- Zambia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1454 , http://hdl.handle.net/10962/d1003335
- Description: This is a qualitative study whose purpose was to investigate the community radio education practices and the museum outreach education activities with a view to understanding how a museum-radio partnership may be used to engage the Livingstone community in environment and sustainability learning. Environment and sustainability issues require a community approach in order to bring about sustained responses to environmental challenges. As such, the study worked with social learning ideas of engaging the community in environment and sustainability learning. The data was generated mainly from face-to-face semi-structured interviews involving three community radio stations, Radio Listener Clubs and museum experts. The data generated was then presented to a strategy workshop involving the Livingstone Museum and Radio Musi-otunya staff. Arising from this workshop, recommendations were made about the possibility of the museum working in partnership with the radio to engage the community in environmental education. The study has shown that much of the museum environmental education activities have been confined to exhibitions and lectures within the museum building, which has affected the number of people being serviced by the museum. These education activities are arranged such that museum expert-led knowledge is presented to the audience with minimal community engagement on the environmental learning content. The study has also shown that community radio programming provides opportunities for community-led social learning which the Livingstone Museum could make use of to engage the community in environmental learning. Community radio programming allows community participation through Radio Listener Clubs, in identification and presentation of local environmental issues. This makes it a suitable tool to address locally relevant environmental issues, by the local community. Environmental issues are different from one place to another. Therefore environmental education approaches that bring issues into the museum may fail to address the different environmental education issues in different community context. The study concludes by recommending that Livingstone Museum should explore the use of community radio so that their expert knowledge and that of the radio producers could be used to shape environmental education programmes to go beyond awareness-raising.
- Full Text:
Consumer perceptions of private label brands: an Eastern Cape university-aged analysis
- Authors: Mpofu, Bukhosi Dumoluhle
- Date: 2011
- Subjects: House brands -- South Africa -- Eastern Cape Young consumers -- South Africa -- Eastern Cape Consumer behavior -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1167 , http://hdl.handle.net/10962/d1002783
- Description: This research investigates the consumer perceptions of private label brands amongst the university aged consumers from selected Eastern Cape universities. The research also aimed to ascertain whether or not generation Y consumers are aware of the existence of private labels, whether price, quality, advertising, packaging, reference groups and demographic variables influenced generation Y purchasing behavior of private label brands. To achieve these objectives, the research made use of the simple random technique to gather the primary data via the use of an online structured questionnaire. The sample population selected where the students in the Eastern Cape Province Universities (Rhodes and Nelson Mandela Metropolitan Universities) who reside off-campus. The assumption was that students who reside off-campus are more aware of private labels as they carry out shopping more than those that reside on campus and generally would have more disposable income and the reason that two different universities have been chosen is to provide a broad base of student opinions, covering varying cultural and income backgrounds, thus allowing for unbiased, valuable research. After pre-tests were conducted the questionnaire was made available online to easy the distribution of the questionnaire and allow for a greater response rate. Descriptive and inferential statistics where used to analyze the results of the questionnaire. The results showed that consumers are generally aware of private label brands and have at least seen them being advertised. Furthermore, the results showed that consumers purchase groceries based on price, quality and convenience of location of the grocery stores .The results indicate that Generation Y consumers are indeed a significant part of the consumer population and that they represent a confident, self reliant, optimistic and positive generation and are verbally and visually more sophisticated, creating a whole new language through digital media and that Generation Y consumers are generally aware of the existence of private labels. The results also indicate that Generation Y consumers strongly agreed that they purchase groceries based on price and quality, meaning price and quality are very influential when purchasing groceries and that the packaging of, generally, all private label brands was not attractive hence a conclusion was made that packaging of private labeled products does not influence Generation Y’s purchasing behaviour of private labels.
- Full Text:
Curating the reviled, beloved and quotidian: a retrospective of Vladimir Tretchikoff
- Authors: Lamprecht, Andrew Paul
- Date: 2011
- Subjects: Tretchikoff, Vladimir -- Criticism and interpretation Painters -- South Africa -- Criticism and interpretation Curatorship -- South Africa -- Art Kitsch
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2407 , http://hdl.handle.net/10962/d1002203
- Description: This thesis aims to contextualise my curation of 'Tretchikoff: The People's Painter' at the Iziko South African National Gallery by outlining the process by which I came to embark on this project and to examine the concepts of mass art and kitsch in relation to the painter. Mass art, in Noel Carroll's explication of the term, is art that utilises industrial processes of replication. Carroll argues that this leads to specific formal and structural tendencies in this art which have much in common with the pejorative concept of kitsch, or art that is lacking in taste or effuses excessive emotion. The latter term was and continues to be applied to Tretchikoff. Although some have attempted to 'reclaim' the word as a positive concept the negative associations that link this term to Tretchikoff are strong. Interrogating these concepts led me to decide to curate TretchikofPs retrospective by focusing on his painting and not including the prints for which he was so well known. Awareness of the complex associations and 'received knowledge' that his prints engender has influenced several curatorial decisions that I have taken. I consider the intellectual underpinnings of my curatorial strategy and argue for an 'open' exhibition which gives the viewer the opportunity to assess his work and legacy in an objective manner, free from as much curatorial mediation and didacticsm as possible. There are no answers to be offered in my curation of Tretchikxiff the People's Painter, rather I have aimed to set up dialogues, discussions, confrontations and challenges; I have offered simple relationships rather than complex juxtapositions I have aimed to position the artwork as the centre of the engagement relative to the viewer.
- Full Text:
Development of techniques for the isolation of a granulovirus from potato tuber moth, phthorimaea operculella (Zeller)
- Authors: King, Shirley Anne
- Date: 2011
- Subjects: Potato tuberworm -- Larvae , Agricultural pests -- Biological control , Potato tuberworm , Baculoviruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5910 , http://hdl.handle.net/10962/d1015202
- Description: Phthorimaea operculella, commonly known as the Potato Tuber Moth, is an economically important agricultural pest worldwide. The baculovirus, Phthorimaea operculella granulovirus (PhoGV) has been considered as a means of control alternative to chemical control because of its host specificity and harmless impact on other organisms and ecosystems. An isolate of PhoGV obtained from a South African PTM population would be beneficial in the production of a biopesticide, which is not yet available. An efficient and cost-effective rearing method would be advantageous for potential commercial production. Commercial table and seed potato plantations and storage facilities located in Patensie, Bathurst, Howick and Ivanhoe were surveyed for PTM infestations. Patensie was the only site where milky discoloured larvae were found, a potential symptom of PhoGV infection. TEM analysis revealed no virus in these samples. Since no virus was found in the field-collected samples, PTM insects were collected to initiate rearing in the laboratory. PTM was raised by three different methods in the laboratory. A cost/benefit analysis, survival rate, fertility and sex ratio were recorded for each rearing method. Rearing method one was deemed unsuccessful for efficient commercial rearing, as survival percentage and fertility were low. Rearing methods two and three had high survival rates and high fertility, and were efficient and less labour intensive than rearing method one. Rearing method three was the most productive technique, but for commercial production rearing method two was considered the most manageable and efficient. The sex ratio was 1:1 for all three cultures. The cost analysis revealed that rearing methods two and three were less expensive than rearing method one because less labour was required to monitor insects. The success of rearing PTM for 19 months will enable these cultures to be up-scaled to a large production facility for mass rearing. Virus was not found in the field surveys or in laboratory cultures, therefore chemical, temperature, humidity and carbon dioxide stressors were used in an attempt to initiate a baculoviral infection. Symptoms were exhibited in larvae subjected to chemical, temperature and humidity treatments, but these were confirmed by TEM analysis not to be a result of PhoGV infection. The success of rearing PTM in the laboratory suggests that the method could be used in the commercial rearing of the insects in a large mass-rearing facility. The data obtained from induction protocols have allowed for better understanding for future induction for PhoGV and other baculoviruses in other insect species. The failure to isolate a South African PhoGV strain for developing a biopesticide against PTM has motivated further studies in obtaining a baculovirus in order for South Africa to develop a commercial product against this pest.
- Full Text:
Development, manufacture and assessment of Clobetasol 17-propionate cream formulations
- Authors: Fauzee, Ayeshah Fateemah Beebee
- Date: 2011
- Subjects: Adrenocortical hormones , Adrenocortical hormones -- Physiological effect , Adrenocortical hormones -- Testing , Drugs -- Testing , Drugs -- Development , Dermatopharmacology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3856 , http://hdl.handle.net/10962/d1013324
- Description: Eczema or dermatitis is the most common dermatological condition accounting for one-third of all diagnoses in the total population surveyed in South Africa. The prevalence of seborrhoeic dermatitis, extreme photodermatitis and severe psoriasis has increased markedly over the last decade and this increase may be ascribed to the HIV epidemic, first diagnosed in South Africa in 1982. Potent innovator corticosteroids, such as clobetasol 17-propionate (CP) that are used to treat skin disorders, are expensive and there is therefore a need for the production of generic topical corticosteroid products. Formulation and manufacturing processes can be challenging aspects for formulation scientists to produce a robust product that will elicit an appropriate and desirable pharmacokinetic-pharmacodynamic profile. Laboratory scale CP creams were manufactured using different concentrations of Gelot® 64 and propylene glycol in order to establish a composition that would produce a formulation, with similar physical and chemical characteristics and in vitro release profile as an innovator product, Dermovate®. These formulations were assessed in terms of their viscosity, spreadability, pH, content uniformity and in vitro release characteristics using a Franz diffusion cell apparatus. A formulation containing 3% w/w Gelot® 64 and 46% v/v propylene glycol (CPLS-02) was found to exhibit similar viscosity and spreadability characteristics and released CP in a manner similar to Dermovate®. The mechanism of drug release was evaluated using mathematical models such as zero order, first order and Higuchi models. In addition, the in vitro release profiles were characterised by use of difference (f1) and similarity (f2 and Sd) factors. A scale-up formulation with the same % w/w composition as the laboratory scale was also investigated following manufacture using a Wintech® cream/ointment mixer. A Central Composite Design approach was used to investigate the effect of process variables on the performance of the scale-up cream formulations. The homogenisation speed, anchor speed, homogenisation time and cooling time were the process variables investigated. Thirty scale-up batches were manufactured and analysed in terms of their viscosity, spreadability, pH, % drug content and cumulative % drug released per unit area over 72 hours. Model fitting using Design-Expert® software was undertaken and revealed that a correlation between the process variables and the cream responses was most suitably described by quadratic polynomial relationships. The homogenisation speed had the most significant effect on the quality of the scale-up formulations, whereas the anchor speed had a secondary effect on the measured responses, for the formulations investigated. The qualitative interpretation and statistical analysis of the in vitro release data from the scale-up formulations using ANOVA and the f1, f2 and Sd factors revealed that one scale-up batch (CPSU-04), for which the process variables were a homogenisation speed of 1900 rpm, an anchor speed of 35 rpm, a homogenisation time of 100 minutes and a cooling time of 100 minutes, released CP at a similar rate and extent to Dermovate®. A diffusion-controlled mechanism appeared to be predominant in these formulations. A human skin blanching study, using both visual and chromameter assessments, was performed to establish whether batch CPSU-04 was bioequivalent to Dermovate®. The bioequivalence of the selected scale-up formulation to Dermovate® was confirmed, following the calculation of a 90% CI.
- Full Text: