SphereZyme (TM) technology for enhanced enzyme immobilisation application in biosensors
- Authors: Molawa, Letshego Gloria
- Date: 2011
- Subjects: Immobilized enzymes , Hydrolases , Hydrolysis , SphereZyme , Biosensors , Proteolytic enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3989 , http://hdl.handle.net/10962/d1004048 , Immobilized enzymes , Hydrolases , Hydrolysis , SphereZyme , Biosensors , Proteolytic enzymes
- Description: Self-immobilisation enzyme technologies, such as SphereZyme™, suffer from the lack of applicability to hydrolyse large substrates. Solid support immobilisation is usually a method of choice, to produce a stable biocatalyst for large substrates hydrolysis in the industry. In order to investigate this limitation, a commercial protease called Alcalase® was chosen as a model enzyme due to its natural activity (hydrolysis of large substrates-proteins). Prior to immobilising through the SphereZyme™ technology, Alcalase® was partially purified through dialysis followed by CM Sepharose™ FF cation exchanger. Sample contaminants, such as salts and stabilisers can inhibit protein crosslinking by reacting with glutaraldehyde. Alcalase® was successfully separated into 3 proteases with the major peak correlating to a positive control run on native PAGE, indicating that it was likely subtilisin Carlsberg. A 16% alkaline protease activity for azo-casein hydrolysis was retained when 5% v/v PEI: 25% v/v glutaraldehyde solution was used as a crosslinking agent in Alcalase® SphereZyme™ production. An increase in activity was also observed for monomeric substrates (PNPA) where the highest was 55%. The highest % activities maintained when 0.33 M EDA: 25% v/v glutaraldehyde solution was initially used as crosslinking agent were 4.5% and 1.6% for monomeric and polymeric substrates, respectively. PEI is a hydrophilic branched polymer with an abundance of amine groups compared to EDA. A comparison study of immobilisation efficiencies of SphereZyme™, Eupergit® and Dendrispheres was also performed for large substrate biocatalysis. The two latter technologies are solid-support immobilisation methods. Dendrispheres reached its maximum loading capacity in the first 5 minute of the one hour binding time. Twenty minutes was chosen as a maximum binding time since there was constant protein maintained on the solid support and no enzyme loss was observed during the 1 hour binding time. PEI at pH 11.5, its native pH, gave the highest immobilisation yield and specific activity over the PEI pH range of 11.5 to 7. SphereZyme™ had the highest ratio for azocasein hydrolysis followed by Dendrispheres and Eupergit®. The SphereZyme™ was also shown to be applicable to biosensors for phenol detection. Different modifications of glassy carbon electrode (GCE) were evaluated as a benchmark for the fabrication of SphereZyme™ modified phenol biosensor. GCE modified with laccase SphereZyme™ entrapped in cellulose membrane was the best modification due to the broad catechol range (<0.950 mM), high correlation coefficient (R2, 0.995) and relative high sensitivity factor (0.305 μA.mM-1). This type of biosensor was also shown to be electroactive at pH 7.0 for which its control, free laccase, lacked electroactivity. From the catalytic constants calculated, GCE modified with laccase SphereZyme™ entrapped in cellulose membrane also gave the highest effectiveness factor (Imax/Km app) of 1.84 μA.mM-1. The modified GCE with Alcalase® SphereZyme™ was relatively more sensitive than GCE modified with free Alcalase®.
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- Date Issued: 2011
Slow delivery of low-income housing at munipal level with special reference to the Nelson Mandela Bay Munipality
- Authors: Scheepers, Mario Jacques
- Date: 2011
- Subjects: SLow-income housing -- South Africa -- Port Elizabeth , Municipal services -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9671 , http://hdl.handle.net/10948/d1015968
- Description: The provision of adequate housing is an important part of government's commitment towards providing a better quality of life to the people of South Africa. Housing delivery is, however, not taking place to the extent and speed that will eliminate the backlog in housing delivery. The researcher aims to (i) evaluate and investigate the reasons why housing delivery at municipal level is slow, (ii) discuss the effect of inefficient implementation on delivery, (iii) examine the influence of the lack of infrastructure and the lack of skilled municipal officials and employees of construction organisations and the processes followed to make a success of housing delivery. Chapter 2, Section 26(1), Act 108 0f 1996 of the Constitution of South Africa states that everyone has the right to have access to adequate housing. This places an obligation on government to provide adequate housing to all citizens, within the restriction of available resources. The lack of land hampers the speed at which municipalities can deliver low-income housing. Housing and basic infrastructure (water, sewer and roads) form an integral part of the governments commitment to reduce poverty and improve the quality of life of South Africans. The fact that municipalities do not have capacity to address housing delivery and the fact that most artisans are near retirement age also influence the rate that houses can be delivered. Adequate housing processes are needed for housing delivery to take place, without it government will not succeed in delivering adequate housing. The results of the survey and the literature review confirm that housing delivery at municipality level is slow, that municipal officials need training and more employees to insure that housing delivery improves. The results also show the importance of infrastructure and land, the importance of implementing housing policies and processes adequately.
- Full Text:
- Date Issued: 2011
Incorporation of Ni(II)-dimethylglyoxime ion-imprinted polymer into electrospun polysulphone nanofibre for the determination of Ni(II) ions from aqueous samples
- Authors: Rammika, M , Darko, G , Torto, N
- Date: 2011
- Language: English
- Type: Article
- Identifier: vital:6589 , http://hdl.handle.net/10962/d1004172
- Description: Ni(II)-dimethylglyoxime ion-imprinted polymer (Ni(II)-DMG IIP) was encapsulated in polysulphone and electrospun into nanofibres with diameters ranging from 406 to 854 nm. The structures of the Ni(II)-DMG encapsulated-IIP nanofibre, non-imprinted encapsulated-polymer nanofibre and polysulphone nanofibre mats were observed by scanning electron microscopy and evaluated by infrared spectroscopy. Electrospinning increased the specific surface area of the Ni(II)-DMG encapsulated-IIP nanofibre mats, as was evidenced by the low masses of the Ni(II)-DMG encapsulated-IIP nanofibre mats used. The accuracy of the method was validated by analysing a custom solution of certified reference material (SEP-3); the concentration of Ni(II) obtained was close to the certified one. The limit of detection was found to be 4.0x10-4 μg∙mℓ−1 while the limit of quantification was found to be 1.2x10-3 μg∙mℓ−1. The recovery of Ni(II) achieved using the Ni(II)-DMG imprinted nanofibre mats in water samples was found to range from 83 to 89%, while that of non-imprinted nanofibre mats was found to range from 59 to 65%, and that of polysulphone from 55 to 62%.
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- Date Issued: 2011
Going against the tide: seeking regulations for private military/security companies in a globalized world
- Authors: Juma, Laurence
- Date: 2011
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/128822 , vital:36163 , https://hdl.handle.net/10520/EJC85398
- Description: This article discusses the role of privatization of security in Africa, but its focus is on private military and security companies (PMSCs). The article proceeds on the basis that there is need for effective regulatory frameworks for PMSCs that operate in conflict zones of Africa. Thus, it begins by appraising the existing normative standards at the international, regional and domestic level that apply to these companies, and thereafter, identifies their shortcomings in light of the prevailing security conditions within the continent. The article then posits broad theoretical imperatives for designing a more effective regulatory framework for PMSCs and concludes by proposing the establishment an overarching continental regime constructed on the basis of the suggested imperatives.
- Full Text: false
- Date Issued: 2011
An investigation into Southern African university students' use of proactive coping style
- Authors: Paddey, Michelle
- Date: 2011
- Subjects: College students -- Africa, Southern -- Life skills , Stress management , Stress in adolescence
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9396 , http://hdl.handle.net/10948/2074 , College students -- Africa, Southern -- Life skills , Stress management , Stress in adolescence
- Description: Proactive coping involves individuals developing resources to facilitate their promotion toward personal growth. The aim of this study was to determine whether differences occurred in the use of a proactive coping style between students from various Southern African countries and universities, in order to form cross-cultural comparisons for this construct. The Proactive Coping Inventory (PCI) was electronically distributed to collect the empirical data, with purposeful non-probability sampling being employed. The sample consisted of 622 students from three universities, one each in Botswana, Namibia and South Africa. Eleven hypotheses were set for investigation. Exploratory factor analysis resulted in the emergence of two distinct factors in the PCI, implying two separate subscales. A statistically significant relationship was found between proactive coping and both instrumental and emotional support seeking. A small, practically significant gender difference was discovered for emotional support seeking, and moderate differences were found between age and proactive coping. Southern African university students exhibit higher levels of proactive coping than preventative coping, strategic planning or emotional support seeking. Furthermore, they make use of proactive coping to a greater extent than individuals outside of the Southern Africa region. In terms of national and institutional culture, no statistically significant differences occurred for proactive coping between any of the countries or universities under study. These findings imply that regardless of a Southern African student's home country or university, he or she is likely to cope proactively. A possible explanation is because Africans generally value social support systems and collectivism, which assist individuals in coping proactively. These results also suggest that all three universities under study are effectively encouraging students to cope in a proactive manner, whether formally or informally, which is in line with the values of these institutions. It is recommended that Southern African universities focus more intentionally on becoming positive socialising systems through integrating the development of human strengths, thus enhancing the value that students and society gain from tertiary education. These findings add to the current body of knowledge relating to proactive coping, which is lacking in a Southern African context.
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- Date Issued: 2011
Effects of habitat patch size and isolation on the population structure of two siphonarian limpets
- Authors: Johnson, Linda Gail
- Date: 2011
- Subjects: Siphonaria , Limpets , Population biology , Marine ecology , Habitat selection , Animals -- Dispersal , Ecological heterogeneity , Animal populations , Biodiversity
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5679 , http://hdl.handle.net/10962/d1005364 , Siphonaria , Limpets , Population biology , Marine ecology , Habitat selection , Animals -- Dispersal , Ecological heterogeneity , Animal populations , Biodiversity
- Description: Habitat fragmentation is a fundamental process that determines trends and patterns of distribution and density of organisms. These patterns and trends have been the focus of numerous terrestrial and marine studies and have led to the development of several explanatory hypotheses. Systems and organisms are dynamic and no single hypothesis has adequately accounted for these observed trends. It is therefore important to understand the interaction of these processes and patterns to explain the mechanisms controlling population dynamics. The main aim of this thesis was to test the effect of patch size and isolation on organisms with different modes of dispersal. Mode of dispersal has previously been examined as a factor influencing the effects that habitat fragmentation has on organisms. Very few studies have, however, examined the mode of dispersal of marine organisms because it has long been assumed that marine animals are not directly influenced by habitat fragmentation because of large-scale dispersal. I used two co-occurring species of siphonariid limpets with different modes of dispersal to highlight that not only are marine organisms affected by habitat fragmentation but that they are affected in different ways. The two species of limpet, Siphonaria serrata and Siphonaria concinna, are found within the same habitat and have the same geographic range along the South African coastline, however, they have different modes of dispersal and development. The effect of patch size on organism density has been examined to a great extent with varied results. This study investigated whether habitat patch size played a key role in determining population density and limpet body sizes. The two species are found on the eastern and southern coasts of South Africa were examined across this entire biogeographic range. Patch size was found to have a significant effect on population density of the pelagic developer, S. concinna, but not the direct developing S. serrata. Patch size did play a role in determining limpet body size for both species. S. concinna body size was proposed to be effected directly by patch size whilst S. serrata body size was proposed to be affected indirectly by the effects of the S. concinna densities. The same patterns and trends were observed at five of the seven examined regions across the biogeographic range. The trends observed for S. concinna with respect to patch size conform to the source-sink hypothesis with large habitat patches acting as the source populations whilst the small habitat patches acted as the sink populations. Many previous studies have focused on the effects of habitat patch size at one point in time or over one season. I tested the influence of habitat patch size on the two species of limpets over a period of twelve months to determine whether the trends observed were consistent over time or whether populations varied with time. S. concinna showed a consistently significant difference between small and large patches; whilst S. serrata did not follow a consistent pattern. The mode of dispersal for the two limpets was used to explain the different trends shown by the two species. This examination allowed for the determining of source and sink populations for S. concinna through the examination of fluctuations in limpet body sizes and population densities at small and large habitat patches over twelve months. The direct developing S. serrata trends could not be explained using source-sink theory, as populations were independent from one another. S. serrata demonstrated body size differences at small and large patches which, may be explained by interspecific and intraspecific competition. Habitat isolation is known to play an important role in determining the structure of assemblages and the densities of populations. In this study the population density of the pelagic developing S. concinna showed a weak influence of degree of isolation whilst that of the direct developing S. serrata did not, which may be because of habitat patches along the South African coastline not having great enough degrees of isolation. The population size-structure was influenced directly influenced by isolation for S. concinna, whilst the different population size structure for S. serrata may be explained by assemblage co-dependence. The mode of dispersal showed effects on the relationship of population density and population size-structure with habitat size and isolation. This study indicates the importance of investigating patterns and processes across a range of spatial and temporal scales to gain a comprehensive understanding of factors effecting intertidal organisms.
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- Date Issued: 2011
Evaluating the effect of conservation agriculture basin tillage system on household food security in Mutasa
- Authors: Muchakwana, Thomasina
- Date: 2011
- Subjects: Food security -- Zimbabwe -- Mutasa District , Tillage -- Zimbabwe -- Mutasa District , Agricultural conservation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9113 , http://hdl.handle.net/10948/d1015054
- Description: The research was done with the aim of evaluating the effect of the basin tillage system as a method of conservation agriculture, on improving smallholder farmers’ food security in Mutasa, Manicaland Province in Zimbabwe. This research focussed on the 2010/2011 agricultural season. The main objectives of this study were to determine the contribution of CA basin tillage system on increasing yields per hectare, to evaluate which CA principles are being practiced by smallholder farmers, and to determine how many months the harvested maize will last. The study compares smallholder farmers who practiced CA with farmers who practiced other tillage methods. The other tillage methods are ploughing and conventional hand hoe tillage systems. On average the farmers who practiced CA used 0.47 hectares of land whilst farmers who practiced other tillage methods used an average of 0.43 hectares of land. The average amount of maize produced by smallholder farmers who practiced CA was 824 kg while who practiced other tillage methods produced an average of 498 kg. Farmers practicing CA produced yield with an average of 1175 kg/ha of maize grain while farmers who practiced other tillage methods produced an average of 946 kg/ha. Food security in this reaseach was measured by the amount of months the maize grain produced was lasting in relation with the household size. 57 percent of the farmers who practiced CA are food secure because they have maize grain to last them a full consumption year and moreover surplus. Only 27 percent of the farmers who practiced other tillage methods produced enough to last a full consumption year.
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- Date Issued: 2011
Factors impacting on engineering professionals' decision to seek alternative employment
- Authors: Mkwananzi, Nokuphumula
- Date: 2011
- Subjects: Labor turnover , Engineering -- Vocational guidance
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8749 , http://hdl.handle.net/10948/d1011335 , Labor turnover , Engineering -- Vocational guidance
- Description: The purpose of this study was to determine factors that impacted on engineering professionals’ decision to seek alternative employment, as well as to determine the decision making processes applied by engineering professionals when seeking alternative employment. A conceptual model was developed to illustrate the impact of various factors on labour turnover and the decision making processes that could be followed by engineering professionals when seeking alternative employment. The factors impacting on labour turnover were organised into four categories, namely external, internal, expectations and personal trait factors. The theoretical study revealed that employees were more likely to leave their present organisations if they perceived that there was ample opportunity for acceptable alternative employment (Bigliardi, Petroni & Dormio, 2005). Zimmerman (2008) stated that employee turnover was a problem faced by all organisations globally. In their study they mentioned that high labour turnover rates have been associated with decreased customer satisfaction, productivity, future revenue growth and profitability. A sense of instability and frustration can also cause work backlogs and slow productivity. At times employees lose faith in their organisations as more individuals seek alternative employment (Drake International, 2010). When the organisation experiences high turnover, burnout also increases and could possibly lead to stayers also seeking alternative employment. Previous studies contain evidence of an extensive poaching of South African engineering professionals (technologists and engineers) by overseas companies (Du Toit & Roodt, 2009). As a result of this mobility and the lack of significant engineering graduates entering the industry, companies competed for a limited number of engineering professionals. This challenge resulted in a higher labour turnover rate among engineers as the demand for engineering professionals was higher than the supply. The skills shortage of engineering professionals in South Africa was one of the perceived contributing factors impacting engineering professionals’ decision to seek alternative employment. Apart from the shortage of skills there were other factors that impacted on engineering professionals’ decision to seek alternative employment. External factors, such as slow recruitment due to the low economy, have been identified as having an impact on labour turnover rates. Bigliardi et al (2005) stated that external factors, also referred to as push factors, such as changes in economic, social and technological conditions,created challenges for retaining engineering professionals. Through developing multivariate models that combine a number of factors contributing to labour turnover and empirically testing these models, researchers have attempted to predict why individuals decide to seek alternative employment (MINTRAC, 2010). The job search process was evaluated and referred to as the process of looking for alternatives to a current job, and the evaluation of those alternatives (Brown, 2009). Various decision making models, including the rational decision making model, Steers and Mowday’s model, image theory and the unfolding path model were studied to provide an understanding of how engineering professionals decided whether to seek alternative employment. Donnell and Quirin (2006) explained two decision making models. These are the image theory and Lee and Mitchell’s unfolding model. According to Zimmerman (2008), the studies carried out did not clearly reflect the impact of individual characteristic factors. An empirical study, by means of a survey and a questionnaire as a data collecting tool, was conducted to determine the factors that impacted on engineering professionals at GIBB to seek alternative employment and the decision making process they applied in seeking alternative employment. This study reflected that personal traits such as openness to new experiences, high levels of competency, the ability to form relationships at work, a general level of commitment, ability to incorporate other people’s views at work and a general positive attitude towards work itself influenced the decision to seek alternative employment. The external, internal, expectancy and personal trait factors that were perceived to be the most influential in impacting on engineering professionals’ decision to seek alternative employment were presented in a revised concept model. This model could be valuable for developing retention strategies at GIBB. Future research that could be beneficial to GIBB and the engineering industry was also identified.
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- Date Issued: 2011
On the design and monitoring of photovoltaic systems for rural homes
- Authors: Williams, Nathaniel John
- Date: 2011
- Subjects: Photovoltaic cells , Dwellings -- Power supply
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10516 , http://hdl.handle.net/10948/1308 , Photovoltaic cells , Dwellings -- Power supply
- Description: It is estimated that 1.6 billion people today live without access to electricity. Most of these people live in remote rural areas in developing countries. One economic solution to this problem is the deployment of small domestic photovoltaic (PV) systems called solar home systems (SHS). In order to improve the performance and reduce the life cycle cost of these systems, accurate monitoring data of real SHSs is required. To this end, two SHSs typical of those found in the field were designed and installed, one in a rural area of the Eastern Cape of South Africa and the other in the laboratory. Monitoring systems were designed to record energy ows in the system and important environmental parameters. A novel technique was developed to correct for measurement errors occurring during the utilization of pulse width modulation charge control techniques. These errors were found to be as large as 47.6 percent. Simulations show that correction techniques produce measurement errors that are up to 20 times smaller than uncorrected values, depending upon the operating conditions. As a tool to aid in the analysis of monitoring data, a PV performance model was developed. The model, used to predict the maximum power point (MPP) power of a PV array, was able to predict MPP energy production to within 0.2 percent over the course of three days. Monitoring data from the laboratory system shows that the largest sources of energy loss are charge control, module under performance relative to manufacturer specifications and operation of the PV array away from MPP. These accounted for losses of approximately 18-27 percent, 15 percent and 8-11 percent of rated PV energy under standard test conditions, respectively. Energy consumed by loads on the systems was less than 50 percent of rated PV energy for both the remote and laboratory systems. Performance ratios (PR) for the laboratory system ranged from 0.38 to 0.49 for the three monitoring periods. The remote system produced a PR of 0.46. In both systems the PV arrays appear to have been oversized. This was due to overestimation of the energy requirements of the loads on the systems. In the laboratory system, the loads consisting of three compact fluorescent lamps and one incandescent lamp, were used to simulate a typical SHS load pro le and collectively consumed only 85 percent of their rated power. The 8 predicted load profile for the remote system proved to be signi cantly overestimated. The results of the monitoring project demonstrate the importance of acquiring an accurate estimation of the energy demand from loads on the system. Overestimations result in over-sized arrays and energy lost to charge control while under-sized systems risk damaging system batteries and load shedding. Significant under-performance of the PV module used in the laboratory system, underlines the importance of measuring module IV curves and verifying manufacturer specifications before system deployment. It was also found that signi cant PV array performance gains could be obtained by the use of maximum power point tracking charge controllers. Increased PV array performance leads to smaller arrays and reduced system cost.
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- Date Issued: 2011
Key safety, security, service and legal measures reuired for the successful management of a guest house
- Authors: Horn, Maryke Eda
- Date: 2011
- Subjects: Boardinghouses -- South Africa -- Management , Hospitality industry -- South Africa , Hospitality industry -- South Africa -- Safety measures , Boardinghouses -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8986 , http://hdl.handle.net/10948/1390 , Boardinghouses -- South Africa -- Management , Hospitality industry -- South Africa , Hospitality industry -- South Africa -- Safety measures , Boardinghouses -- Law and legislation -- South Africa
- Description: The significant growth in the South African tourism industry in recent years has placed much focus on the hospitality sector in the country. The hospitably sector performs a vital role in the South African economy, as is the case globally, to provide accommodation to international and national tourists. Guest houses in particular have become one of the fastest growing components of the South African tourism industry. However, operating a guest house is not merely providing a bed, shower and breakfast facility for which a client pays and hopefully returns again in future. Rather, it involves significantly more than providing physical amenities. Not only does a potential entrepreneur require a suitable facility in a well-positioned location, but guest house owners and management must adhere to various strenuous safety, security and service measures, as well as municipal by-laws, in a tough and ever-changing business environment. The central theme and the main objective of this study was to investigate the safety, security, service and legal measures that need to be adhered for the successful management of a guest house in the Nelson Mandela Bay Metro. Together with an outline of the various steps required to start a guest house, a sub-objective was to compile a guest house manual that can be used by new and existing guest house owners and managers to improve their business. The target group was divided into two sections, namely guest house owners and managers on the one hand, and guest house clients on the other - hence two separate questionnaires were developed and used as measuring instrument for the empirical study. The results revealed that clients in the Metro are in general satisfied with the service they receive and safety they experience when staying in guest houses in the Metro. The premises are mostly neat and clean, the towels and bedding are regularly replaced and clean, while the parking bays are sufficient and safe, staff members friendly and approachable, and bookings are done promptly. Over and above the different by-laws to observe, it is the duty of owners and management to provide clients with a safe, secure environment with excellent service, and with sufficient lighting at the entrances, parking and reception areas. All staircases should be steady and iv non-slip, and swimming pools should have secured fencing around and/ or should be covered by safety nets. Staff should follow the correct procedures in emergencies, while concerted efforts should be made to adapt guest houses for the specific needs of disabled and elderly clients. To prevent the outbreak of food poisoning, and to ensure personal and kitchen hygiene, as well as the correct storing of food, are other important responsibilities of owners and management. Therefore, for a guest house to be managed successfully, the owners and management must take into consideration the required safety, security, service and legal measures.
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- Date Issued: 2011
The effectiveness of livestock guarding dogs for livestock production and conservation in Namibia
- Authors: Potgieter, Gail Christine
- Date: 2011
- Subjects: Livestock protection dogs -- Namibia , Herding dogs -- Namibia , Livestock -- Predators of -- Control -- Namibia , Livestock -- Losses -- Namibia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10680 , http://hdl.handle.net/10948/1666 , Livestock protection dogs -- Namibia , Herding dogs -- Namibia , Livestock -- Predators of -- Control -- Namibia , Livestock -- Losses -- Namibia
- Description: The use of livestock guarding dogs (LGDs) to mitigate farmer-predator conflict in Namibia was evaluated. As farmer-predator conflict has two sides, LGDs were evaluated in terms of livestock production and conservation. The main objectives in terms of livestock production were to document: 1) the perceived ability of LGDs to reduce livestock losses in a cost-effective manner; 2) the farmers’ satisfaction with LGD performance; and 3) factors influencing LGD behaviour. The main objectives in terms of conservation were to record: 1) predator killing by farmers relative to LGD introduction; 2) direct impacts of LGDs on target (damage-causing) species; and 3) the impact of LGDs on non-target species. This evaluation was conducted on LGDs bred by the Cheetah Conservation Fund (CCF) and placed on farms in Namibia. The data were collected during face-to-face interviews with farmers using LGDs. Historical data from the CCF programme were used in conjunction with a complete survey of the farmers in the CCF LGD programme during 2009-2010. In terms of livestock production, 91 percent of the LGDs (n = 65) eliminated or reduced livestock losses. Subsequently, 73 percent of the farmers perceived their LGDs as economically beneficial, although a cost-benefit analysis showed that only 59 percent of the LGDs were cost-effective. Farmers were generally satisfied with the performance of their LGDs. However, farmer satisfaction was more closely linked to good LGD behaviour than the perceived reduction in livestock losses. The most commonly-reported LGD behavioural problems (n = 195) were staying at home rather than accompanying the livestock (21 percent) and chasing wildlife (19 percent). LGD staying home behaviour was linked to a lack of care on subsistence farms, as high quality dog food was not consistently provided. Care for LGDs declined with LGD age on subsistence, but not commercial, farms. In terms of conservation, predator-killing farmers killed fewer individuals in the year since LGD introduction than previously; this result was only significant for black-backed jackal Canis mesomelas. However, 37 LGDs killed jackals, nine killed baboons Papio ursinus, three killed caracals Caracal caracal and one killed a cheetah Acinonyx jubatus (n = 83). Farmers and LGDs combined killed significantly more jackals in the survey year than the same farmers (n = 36) killed before LGD introduction. Conversely, five farmers killed 3.2 ± 2.01 cheetahs each in the year before LGD introduction, whereas LGDs and these farmers combined killed only 0.2 ± 0.2 cheetahs per farm in the survey year. Only 16 LGDs (n = 83) killed non-target species. The high LGD success rate in terms of livestock production was facilitated by livestock husbandry practices in the study area. In terms of conservation, LGDs were more beneficial for apex predators than for mesopredators and had a minor impact on non-target species.
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- Date Issued: 2011
Studies in South African marine molluscan chemistry
- Authors: Bromley, Candice Leigh
- Date: 2011
- Subjects: Mollusks -- South Africa , Marine invertebrates -- South Africa , Marine metabolites -- South Africa , Chemical oceanography -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4356 , http://hdl.handle.net/10962/d1005021
- Description: This thesis investigates the variability occurring in the secondary metabolites produced by three South African marine molluscs. Chapter Two discusses the isolation and spectroscopic structure elucidation of the metabolites isolated from two Siphonaria species. The re-investigation of Siphonaria capensis yielded siphonarienfuranone (2.2) as the only common polypropionate isolated from both the 1998 and 2009 collections of S. capensis from the same areas suggesting possible seasonal or genetic variation in polypropionate production. The sterol cholest-7-en-3,5,7- triol (2.33) was also isolated form the 2009 collection of S. capensis and this is the first time this compound has been isolated from a Siphonaria species. The second species, Siphonaria oculus is closely related to S. capensis and the investigation into the former’s secondary metaboliteproduction revealed 2.2 as a major metabolite suggesting an inter-species overlap in polypropionate production. Three new polypropionate metabolites, 2.35, 2.36 and 2.37 were also isolated from S. oculus. An unsuccessful attempt was made to establish the absolute configuration of 2.37 using the modified Mosher’s method and the limited amount of 2.37 available prevented any further attempts at resolving the absolute configuration of this compound. The 1H NMR analysis of the defensive mucus collected directly from S. oculus revealed the presence of the acyclic polypropionate 2.37 as a minor metabolite. The absence of characteristic signals for the furanone containing compounds 2.2, 2.35 and 2.36, might suggest that these compounds cyclise from a hypothetical acyclic precursor (2.38) during standard work up of bulk acetone extracts of Siphonaria species. Chapter Three discusses the re-isolation and spectroscopic structure elucidation of the metabolites isolated from the nudibranch, Leminda millecra. Three known natural products, millecrone A (3.1), 8-hydroxycalamenene (3.6) and cubebenone (3.8) were re-isolated from our 2010 collection of L. millecra, as well as the new minor metabolite 8-acetoxycalamenene (3.16). The cytotoxic prenylated toluquinones and toluhydroquinones (3.9-3.15) initially isolated from the 1998 collection of L. millecra were not found in the 2010 collection supporting the hypothesis that these compounds may be of fungal origin. L. millecra clearly shows variability in the compounds sequestered by this species with millecrone A (3.1) being the only common metabolite in the three investigations of L. millecra to date. An unsuccessful attempt was made to establish the absolute configuration of 3.1, 3.6 and 3.8 through initial LAH reduction of the ketone moiety contained in 3.1 and 3.8 and esterification of the resultant diastereomeric alcohol mixtures and the phenol functionality in 3.6 with (1S)-camphanic chloride. Crystallisation of the (S)- camphanate esters of 3.6 and 3.8 for X-ray analysis were unsuccessful, while the unexpected conjugate addition of a hydride in 3.1 resulted in complex diastereomeric mixtures which could not be separated by HPLC.
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- Date Issued: 2011
Work-family conflict, stress and some demographic and occupational variables among female factory workers in East London, South Africa
- Authors: Dywili, Mtutuzeli
- Date: 2011
- Subjects: Work and family -- South Africa , Job stress -- South Africa , Women employees -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/24128 , vital:62382
- Description: The study examines work-family conflict, stress, and some demographic and occupational variables among female factory workers in East London, South Africa. The participants were female factory workers in East London, South Africa. The independent variables for the study were, demographic and occupational variables, while stress is the dependent variable. Work-family conflict is dependent on demographic and occupational variables, while on the other hand is independent to stress. The demographic variables concerned are age, marital status, number of children and age of the last born child. The occupational variable on the other hand is occupational level, i.e. managerial versus non-managerial. The measuring instruments were a self-designed questionnaire to measure the demographic and occupational variables, a questionnaire developed by Stephens and Sommer (1996) to measure work-family conflict (cronbach’s alpha = 0,90) and the Effort – Reward Imbalance (ERI) questionnaire (Pikhart, Bobak, Siegrist, Pajak, Rywick, Kyshegyi, Gostaus, Skodova& Marmot, 1996) to measure stress at workplace. Cronbach’s alpha for the whole questionnaire reaches the value of 0,89. , Thesis (MCom) -- Faculty of Management and Commerce, 2011
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- Date Issued: 2011
Response and adherence of HIV positive women to cervical cancer treatment
- Authors: Ngugi, Pearl
- Date: 2011
- Subjects: HIV infections -- Chemotherapy -- South Africa , Patient compliance -- South Africa , Cervix uteri -- Cancer -- Treatment , HIV-positive women -- South Africa , Antiretroviral agents -- South Africa
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:10162 , http://hdl.handle.net/10948/d1014129
- Description: It is estimated that 6742 South African women are diagnosed with cervical cancer and 3681 women die from the disease every year. In 1993, The Centers for Disease Control declared cervical cancer an Acquired Immunodeficiency Syndrome defining illness. Apart from persistent human papillomavirus infection, HIV infection is the most common co-factor contributing to cervical cancer in South Africa. Studies have noted that in HIV positive women, there has been an occurrence of faster progression to more advanced stages of cervical cancer with high cases of treatment failure and recurrence. There is limited literature available regarding the prognosis of HIV positive women who suffer from cervical cancer. Women who are HIV positive and have cervical cancer have not been evaluated in detail regarding their response and adherence to cervical cancer treatment. Standard treatment protocols for this set of patients have not been defined. The aim of this study was to assess how HIV positive women who have been diagnosed with cervical cancer responded and adhered to cervical cancer therapy which includes: curative radiotherapy; curative chemotherapy; concurrent chemoradiation or palliative radiotherapy. The study also evaluated the effects of the concurrent use of antiretrovirals and cervical cancer treatment. This was done to determine whether invasive cervical cancer in women who were HIV positive could be managed using the same treatment protocols as patients who were HIV negative. A historical cohort design was employed for the study. The study was conducted at the Oncology Department of a tertiary level hospital located in the Eastern Cape Province, South Africa. The total sample consisted of 196 medical records of women diagnosed with cervical cancer between 2005 and 2008. One hundred women were HIV negative, 83 were HIV positive and the HIV status of 13 women could not be determined. The records were audited over a period of two years from the date of diagnosis. The term „complete response‟ referred to patients who had no recurrence of cervical cancer and no evidence of metastases after undergoing treatment. At one month following treatment there was a significant difference in the incidence of complete response between the HIV positive patients and the HIV negative patients (Chi2 = 16.4, d.f. = 1, p = 0.00005, Cramer‟s V = 0.31). The significant difference in response to treatment between the HIV positive patients and the HIV negative patients was maintained at six months after treatment (Chi2 = 15, d.f. = 1, p = 0.00011, Cramer‟s V = 0.34), 12 months after treatment (Chi2 = 20.5, d.f. = 1, p = 0.00001, Cramer‟s V = 0.37), 18 months after treatment (Chi2 = 9.8, d.f. = 1, p = 0.00173, Cramer‟s V = 0.28) and 24 months after treatment (Chi2 = 5.0, d.f. = 1, p = 0.02571, Cramer‟s V = 0.26). At each of these intervals, cases of treatment failure and metastases were significantly higher in the HIV positive women than in the HIV negative women. Although there was no significant difference in the incidence of adherence between the HIV negative women, the HIV positive women who were on HAART and the HIV positive women who were not on HAART, there was a significant difference in the incidence of the various reasons for non adherence between the various groups. These reasons included: missed scheduled appointments (Chi2 = 2.9, d.f. = 2, p = 0.02385, Cramer‟s V = 0.31); low blood count (Chi2 = 4.0, d.f. = 2, p = 0.01327, Cramer‟s V = 0.15); radiotherapy induced skin breakdown (Chi2 = 0.6, d.f. = 2, p = 0.04581, Cramer‟s V = 0.16) and radiotherapy induced diarrhoea (Chi2 = 6.9, d.f. = 2, p = 0.03118, Cramer‟s V = 0.19). According to the 2004 National Antiretroviral Treatment Guidelines, cervical cancer patients would fall into the WHO stage IV category of HIV disease thus all patients with confirmed diagnosis of invasive cervical cancer should be commenced on antiretrovirals as soon as the cancer diagnosis is made regardless of their CD4 count. However, in the current study, 13 percent (n= 83) of the HIV positive women were not on antiretrovirals. The study concluded that HIV positive women had a higher incidence of both treatment failure and metastases to cervical cancer treatment. Standard radiotherapy and concurrent chemoradiation cervical cancer treatment protocols should be still be used in both HIV negative patients and HIV positive patients so as not to compromise tumour control. Furthermore, in accordance with the antiretroviral treatment guidelines, all HIV positive patients with cervical cancer should receive antiretrovirals irrespective of their CD4 count.
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- Date Issued: 2011
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
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- Date Issued: 2011
Challenging the forked tongue of multilingualism: scholarship in African languages at SA Universities with specific reference to Rhodes
- Authors: Kaschula, Russell H
- Date: 2011
- Language: English
- Type: Text
- Identifier: vital:586 , http://hdl.handle.net/10962/d1018946 , https://orcid.org/0000-0002-5481-6748
- Description: [From the text] Effective multilingualism will aid SA in creating Social Cohesion (cultural, linguistic), a National Government initiative forming part of language planning. Languages should be seen as part of our environment and “resource package” within an intercultural paradigm. All students exiting School and University must be proficient in an African language and English or Afrikaans.
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- Date Issued: 2011
Living by voices we shall never hear: seeing animals differently
- Authors: Mitchell, Pauline , Mitchell, Les
- Date: 2011
- Language: English
- Type: Monograph
- Identifier: vital:12230
- Description: We live in the midst of animals; the products of their bodies and products made from their bodies are everywhere. Over thousands of years we have used these beings for our own ends; for hauling loads, grinding grain, making roads, carrying people, working in mines, powering machinery, ploughing land and making war. Each day of the year we kill, on average, in the food industry alone, the same number of animals as there are people in the whole of southern Africa. Animals have been our unpaid, unacknowledged and, for the most part, appallingly treated slaves, on whose backs, it is no exaggeration to say, our present world has been built. Perhaps it is time to consider our relationship with them. For this book we originally asked Quakers and people attending Quaker Meetings to write about ‘seeing animals differently’ and our contributors are Friends or attenders or people who have some association with Friends. The authors live in the UK, South Africa, Zimbabwe, New Zealand, Australia and the United States. There is a saying that trying to organise Quakers is like trying to herd cats and the diversity in this small book clearly bears this out. We An introduction to the book Pauline and Les Mitchell Introduction have not made any attempt to impose uniformity or to ask authors to write to any formula, which means that what you read carries the original voice and style of the contributor. We feel that, rather than a weakness, this is a strength of the collection and shows how diverse yet interwoven our perspectives can be.
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- Date Issued: 2011
Expression of heat shock proteins on the plasma membrane of cancer cells : a potential multi-chaperone complex that mediates migration
- Authors: Kenyon, Amy
- Date: 2011 , 2011-03-29
- Subjects: Heat shock proteins , Protein folding , Molecular chaperones , Cancer -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4122 , http://hdl.handle.net/10962/d1013362
- Description: Current dogma suggests that the Heat Shock Protein (Hsp) molecular chaperones and associated co-chaperones function primarily within the cell, although growing evidence suggests a role for these proteins on the plasma membrane of cancer cells. Hsp90 does not function independently in vivo, but instead functions with a variety of partner chaperones and co-chaperones, that include Hsp70 and Hsp90/Hsp70 organising protein (Hop), which are thought to regulate ATP hydrolysis and the binding of Hsp90 to its client proteins. Hsp90 on the plasma membrane appears to have distinct roles in pathways leading to cell motility, invasion and metastasis. We hypothesised that Hsp90 on the plasma membrane is present as part of a multi-chaperone complex that participates in the chaperone-assisted folding of client membrane proteins in a manner analogous to the intracellular chaperone complex. This study characterised the membrane expression of Hsp90, Hsp70 and Hop in different cell models of different adhesive and migratory capacity, namely MDA-MB-231 (metastatic adherent breast cancer cell line), MCF-7 (non-metastatic adherent breast cancer cell line), U937 and THP1 (monocytic leukemia suspension cell lines). Membrane expression of the Hsps was analysed using a combination of subcellular fractionation, biotin-streptavidin affinity purification and immunofluorescence. This study provided evidence to suggest that Hsp90, Hsp70 and Hop are membrane associated in MDA-MB-231 and MCF-7 breast cancer cells. Hsp90, Hsp70 and Hop associated with the plasma membrane such that at least part of the protein is located extracellularly. Immunofluorescence analysis showed that Hsp90, Hsp70 and Hop at the leading edge may localize to membrane ruffles in MDA-MB-231 cells, in accordance with the published role of Hsp90 in migration. An increase in this response was seen in cells stimulated to migrate with SDF-1. By immunoprecipitation, we isolated a putative extracellular membrane associated complex containing Hsp90, Hsp70 and Hop. Using soluble Hsp90 and antibodies against membrane associated Hsp90, we suggested roles for soluble extracellular Hsp90 in mediating migration by wound healing assays and inducing actin reorganisation and vinculin-based focal adhesion formation. The effects of extracellular Hsp90 are mediated by signalling through an ERK1/2 dependent pathway. An anti-Hsp90 antibody against an N-terminal epitope in Hsp90 appeared to be able to overcome the death inducing effects of a combination of SDF-1 and AMD3100, while soluble Hsp90 could not overcome this effect. We propose that this study provides preliminary evidence that extracellular Hsp90 functions as part of a multi-chaperone complex that includes Hsp70 and Hop. The extracellular Hsp90 chaperone complex may mediate cell processes such as migration by modulating the conformation of cell surface receptors, leading to downstream signalling.
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- Date Issued: 2011
An assessment of the effectiveness of public consultation: the case study of selected ward committees in the Northern Bay Municipality
- Authors: Arends, Darrin
- Date: 2011
- Subjects: Municipal government -- South Africa -- Eastern Cape -- Citizen participation , Local government -- South Africa -- Eastern Cape -- Citizen participation , Political planning -- South Africa -- Eastern Cape -- Citizen participation , Communities -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:8187 , http://hdl.handle.net/10948/1535 , Municipal government -- South Africa -- Eastern Cape -- Citizen participation , Local government -- South Africa -- Eastern Cape -- Citizen participation , Political planning -- South Africa -- Eastern Cape -- Citizen participation , Communities -- South Africa -- Eastern Cape
- Description: Since 1994, the South African local government has been obligated to consult with its citizenry in respect of the processes of relating to service delivery. The South African Government has developed a wide range of legislation that ensures that communities are consulted on a continuous basis with regard to how services need to be rendered. Communities have a right to be consulted and to give input into issues affecting them. Public consultation as envisaged in the South African legislation has, however, not yielded the desired results which is evident in the spate of service delivery protests over poor or non service delivery. Therefore, this study seeks to analyse the effectiveness and efficiency of pubic consultation in the Northern Areas of the Nelson Mandela Bay Municipality. The researcher used qualitative research methods since it would provide the reader with more insight into how public consultation is implemented in the Nelson Mandela Bay Municipality. The communities, senior municipal officials, and councillors have been interviewed in a structured manner and a content analysis has been made of the minutes of the ward committees in the Northern Areas, the annual reports of the Municipality’s Oversight Committee and a range of other reading material. A number of findings has been made during this research project with the most pertinent being the non-compliance to certain sections of legislation by the Municipality. The communities in the Northern Areas generally felt that efficient and effective public consultation would reduce the number of service delivery protests in that part of the Municipality. A number of interventions need to be made by the political leadership with regard to public consultation and more resources need to be committed towards those processes.
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- Date Issued: 2011
Institutional constraints to horticulture production and marketing
- Authors: Mphahama, Litsoanelo Evodiah
- Date: 2011
- Subjects: Horticulture -- Economic aspects -- Lesotho , Agricultural extension work -- Lesotho , Gardening -- Lesotho , Food security -- Lesotho , Poverty -- Lesotho , Agricultural productivity -- Lesotho , Farm produce -- Lesotho -- Marketing , Land tenure -- Lesotho
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11182 , http://hdl.handle.net/10353/428 , Horticulture -- Economic aspects -- Lesotho , Agricultural extension work -- Lesotho , Gardening -- Lesotho , Food security -- Lesotho , Poverty -- Lesotho , Agricultural productivity -- Lesotho , Farm produce -- Lesotho -- Marketing , Land tenure -- Lesotho
- Description: Lesotho has a land area of about 30.340 square kilometers and is completely surrounded by the Republic of South Africa. Much of the country is mountainous. Its agricultural sector is characterized by low productivity due to erratic climatic conditions, limited arable land and fragile soils with a low water holding capacity. These conditions have proved very detrimental to crop production, rendering agriculture a risky economic activity. Numerous efforts have been made over the years to address the technical constraints confronting the sector, but nothing seems to be changing. The implication is that the technical/climatic factors mentioned above may be only part of the problem. The current situation whereby Lesotho imports nearly 95% of its domestic food requirements is unsustainable, but this desperate picture looks set to worsen with the continuing threats of contracting farm sizes and further declines in farmer participation rates. But this sector has continued to be an important source of household survival and existence. A study was designed and conducted during 2008 and 2009 to identify the institutional constraints to horticulture production in Lesotho, looking specifically at the obstacles to effective production and marketing of horticultural products. A total of 100 farming households were enumerated in four districts of the country, namely Butha Buthe, Berea, Mafeteng, and Thaba-Tseka. A range of institutional and non-price factors in the farming and marketing environment were incorporated in a binary choice model to investigate the degree of satisfaction of the farming households with their previous year’s farming results. To avoid selection bias in the sample, a probit model was chosen, and the Stata-10 software was used to estimate probit coefficients. The results provide indications that property rights, the agricultural extension service, the condition of the physical infrastructure, and distance to markets may be crucial elements threatening the existence of this sector in Lesotho. The difficulties in accessing markets and land remain important institutional constraints to horticulture production and marketing in Lesotho. Recommendations made on these issues include providing more policy support to homestead gardening and for these issues to be incorporated into the Vision 2020 process. Also to be included is the issue of addressing the growing national food insecurity and enhancing Basotho livelihoods in general.
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- Date Issued: 2011