SAIAB extension opening : lunch for the Deputy-Minister of Science and Technology
- Authors: Badat, Saleem
- Date: 2007
- Subjects: South African Institute of Aquatic Biodiversity (SAIAB)
- Language: English
- Type: text
- Identifier: vital:7657 , http://hdl.handle.net/10962/d1015785
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- Date Issued: 2007
Satellite television use among Zimbabwean professionals : an investigation into audience consumption of SABC Africa's '60 Minutes live in Africa'
- Authors: Mugoni, Petronella Chipo
- Date: 2007
- Subjects: Direct broadcast satellite television -- Zimbabwe Television viewers -- Zimbabwe Television viewers -- Zimbabwe -- Case studies Television broadcasting of news -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3512 , http://hdl.handle.net/10962/d1007707
- Description: Within the context of debates surrounding the consumption of global media by local audiences in Third World countries, this study explores the reasons behind satellite television subscription, and consumption of international news among a sample of young professional men and women in contemporary Zimbabwe. The study seeks to uncover how the research participants respond to news broadcast on SABC Africa's '60 minutes live in Africa', a programme which they can only access via satellite television in their country. Working within the frame of audience studies which insists on understanding media consumption and reception in context, this study examines how the respondents, situated within the specific Zimbabwe context, characterised as it is by serious social, economic and political challenges, respond to both regional news and news about their country on '60 minutes live in Africa'. Within the frame of qualitative research the study employs a two-stage sampling procedure and data collection strategy to uncover the factors that underpin international media consumption and reception by professional men and women situated in a country undergoing rapid change. The findings of the study point to the various social and individual factors that underlie media consumption choices as well as to the different socially patterned reasons why local audiences are either attracted to, or reject global media. The study found that SABC Africa's '60 minutes live in Africa' is more popular and better received than Western-broadcast programmes on channels such as BBC, CNN, and Sky News among Zimbabwean professionals. I also uncovered some evidence that cultural proximity and relevance are of supreme importance in determining which media audiences chose to consume and what level of engagement they bring to their reception of global media. These and other findings directly confront media models that privilege beliefs in cultural imperialism and the dominance of Western media and their effects on Third World audiences.
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- Date Issued: 2007
Securing media streams in an Asterisk-based environment and evaluating the resulting performance cost
- Authors: Clayton, Bradley
- Date: 2007 , 2007-01-08
- Subjects: Asterisk (Computer file) , Computer networks -- Security measures , Internet telephony -- Security measures
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4647 , http://hdl.handle.net/10962/d1006606 , Asterisk (Computer file) , Computer networks -- Security measures , Internet telephony -- Security measures
- Description: When adding Confidentiality, Integrity and Availability (CIA) to a multi-user VoIP (Voice over IP) system, performance and quality are at risk. The aim of this study is twofold. Firstly, it describes current methods suitable to secure voice streams within a VoIP system and make them available in an Asterisk-based VoIP environment. (Asterisk is a well established, open-source, TDM/VoIP PBX.) Secondly, this study evaluates the performance cost incurred after implementing each security method within the Asterisk-based system, using a special testbed suite, named DRAPA, which was developed expressly for this study. The three security methods implemented and studied were IPSec (Internet Protocol Security), SRTP (Secure Real-time Transport Protocol), and SIAX2 (Secure Inter-Asterisk eXchange 2 protocol). From the experiments, it was found that bandwidth and CPU usage were significantly affected by the addition of CIA. In ranking the three security methods in terms of these two resources, it was found that SRTP incurs the least bandwidth overhead, followed by SIAX2 and then IPSec. Where CPU utilisation is concerned, it was found that SIAX2 incurs the least overhead, followed by IPSec, and then SRTP.
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- Date Issued: 2007
Securing softswitches from malicious attacks
- Authors: Opie, Jake Weyman
- Date: 2007
- Subjects: Internet telephony -- Security measures , Computer networks -- Security measures , Digital telephone systems , Communication -- Technological innovations , Computer network protocols , TCP/IP (Computer network protocol) , Switching theory
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4683 , http://hdl.handle.net/10962/d1007714 , Internet telephony -- Security measures , Computer networks -- Security measures , Digital telephone systems , Communication -- Technological innovations , Computer network protocols , TCP/IP (Computer network protocol) , Switching theory
- Description: Traditionally, real-time communication, such as voice calls, has run on separate, closed networks. Of all the limitations that these networks had, the ability of malicious attacks to cripple communication was not a crucial one. This situation has changed radically now that real-time communication and data have merged to share the same network. The objective of this project is to investigate the securing of softswitches with functionality similar to Private Branch Exchanges (PBX) from malicious attacks. The focus of the project will be a practical investigation of how to secure ILANGA, an ASTERISK-based system under development at Rhodes University. The practical investigation that focuses on ILANGA is based on performing six varied experiments on the different components of ILANGA. Before the six experiments are performed, basic preliminary security measures and the restrictions placed on the access to the database are discussed. The outcomes of these experiments are discussed and the precise reasons why these attacks were either successful or unsuccessful are given. Suggestions of a theoretical nature on how to defend against the successful attacks are also presented.
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- Date Issued: 2007
Securitisation and its application to low cost housing finance in South Africa
- Authors: Zimbwa, Allan Golden
- Date: 2007
- Subjects: South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1011 , http://hdl.handle.net/10962/d1002746 , South Africa. Constitution , Human rights -- Government policy -- South Africa , Right to housing -- South Africa , Housing -- Law and legislation -- South Africa , Housing policy -- South Africa , Low income housing -- South Africa
- Description: Section 26 of the Constitution of South Africa Act 108 of 1996 provides that housing is a basic human right and that the government must take reasonable legislative and other measures to achieve the realisation of this right. A number of measures were taken to try to resolve this socio-economic issue. A number of housing institutions were established , various pieces of legislation were passed and housing subsidies were provided. However, housing backlogs remain a challenge. In March 1994 the housing backlog was estimated between 1,3 and 1,8 million units. When more than a million houses were provided by 2001 , the housing backlog had increased to between 2 and 3 million houses. To date subsidies in excess of R29 billion have been spent on housing provision. A study by the Department of Housing concluded that, at the current rate of increase of housing funding vis-a-vis the growing backlog and rapid urbanisation, the household backlog will not be changed in ten years' time. The United States of America (USA) had a similar low cost housing problem, but securitisation alleviated it with the participation of government agencies Fannie Mae, Ginnie Mae and Freddie Mac. In South Africa, the NHFC tried to emulate the USA model by establishing Gateway Home Loans (Pty) Limited (Gateway) in 1999. Gateway, however, was not a success. This research investigates whether securitisation can be applied in South Africa to alleviate the low cost housing issue. The study finds that there is a credit availability gap for the low income sector earning less than R8 000 per month because of the perceived risk of default and unwillingness by banks to lend to this sector. The increase in housing backlog that continues unabated, inadequate housing finance system to low income earners, the lessons learnt from the failure of Gateway, the success factors of the USA securitisation model and the sound and sophisticated South African financial system are the rationale for applying securitisation. A proposal of how to effectively apply securitisation to low cost housing in South Africa is provided with recommendations to revive the primary market.
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- Date Issued: 2007
Segregated housing and contested identities: the case of the King William's Town coloured community, 1895 - 1946
- Authors: Victor, Stephanie Emilia
- Date: 2007
- Subjects: Colored people (South Africa) -- Race identity Colored people (South Africa) -- Political activity South Africa -- Race relations Colored people (South Africa) -- Housing Housing -- South Africa -- King William's Town Colored people (South Africa) -- Relocation Colored people (South Africa) -- South Africa -- King William's Town
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2568 , http://hdl.handle.net/10962/d1002421
- Description: This thesis is a case study of the dynamics of coloured housing in King William's Town between 1895 and 1946. The impact of spatial segregation on pre-apartheid coloured settlements in the Eastern Cape has largely been ignored up to the present. This needs to be rectified as the lack of in-depth enquiry can lead to misinterpretations that may influence contemporary politics and identity formation. Through research based on primary sources, it has become apparent that segregation in King William's Town was safeguarded and rationalized through the discourses of sanitation and civilization, and the practices of relocation and removal. The existing slum cond itions were used as a convenient excuse to implement municipal control. Segregation compounded the problem of poverty, inequitable access to housing and the provision of basic services. As a result, local coloured housing was increasingly characterised by a shortage of decent accommodation and basic services, decreasing home ownership and increasing municipal tenancy. In addition, through the implementation of the 1923 Natives (Urban Areas) Act and the 1934 Slums Act, high sanitation standards were set, but the Council itself provided inferior services. Ironically, conditions in the relocated municipal settlements were also not on par with the provisions stipulated in the Slums Act that were used to effect removal in the first place. The implementation of racially exclusive housing was, therefore, not driven by a single role player. It was pioneered by the local authorities, legalised by national government and supported by the coloured elite, when needed, in an attempt to access decent housing. This occurred mainly through the political manoeuvring of the coloured elite, and specifically the African Political (later People's) Organisation (APO), the Afrikaanse Nasionale Bond (AN B) and the locally constituted Coloured Welfare Association (CWA) in King William 's Town. These organisations attempted to procure access to housing within the narrow boundaries of a prescribed identity. Segregated housing therefore fostered and sustained coloured identity. It consolidated feelings of separateness and division and provided impetus for the construction of race and even racial tension. Coloured identity attempted to serve as a rallying point to overcome differences in religion, family and social networks and place of residence in order to procure access to housing. It was not, however, able to overcome the occasional division between settlements, caused by well-developed placeidentities, which still inform the contemporary housing milieu. The coloured elite initially did not question the legitimacy of coloured identity. Only in 1939, under threats of increased residential segregation, combined with the resulting opposition in coloured protest politics, was the legitimacy of coloured identity publicly contested . By 1943, with the creation of the Coloured Advisory Council (CAC), local coloured unity proved to be insufficient. A division within the ranks of the local coloured elite was evident. As a result, the expression of coloured identity still remains contested in contemporary King William's Town.
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- Date Issued: 2007
Selecting stories to tell: the gatekeeping of international news at SAfm
- Authors: Ticha, Abel Akara
- Date: 2007
- Subjects: South African Broadcasting Corporation SAfm (South Africa) Radio broadcasting -- South Africa Foreign news -- South Africa Radio journalism -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3499 , http://hdl.handle.net/10962/d1004520
- Description: The premise of this thesis is that the selection of international news to be aired on the bulletins of SAfm by SABC Radio News staff is influenced by more complex factors than could be seen solely from the prism of an empirical journalistic paradigm. Drawing from data obtained through participant observation and interviewing, it is noted that there has been a revolution from a propagandist approach during apartheid to a professional approach following the demise of apartheid, in the selection of international news for bulletins on SAfm. Using Lewin's theory of forces in decision making and locating it within four out of five levels of a framework of gatekeeping analysis provided by Shoemaker (1991) and Shoemaker et al (200 I), it is concluded that the delimiting well-tested routines of newsmaking act as powerful companions of individuals' selection decisions of international news broadcast on SAfm's bulletins. However, these routines are adapted to meet the organisational demands of the SABC, which as a Public Service Broadcaster (PBS) has embraced the discourse of South African nationalism/panAfricanism, as a major philosophy underpinning the Corporation's coverage of the world. Therefore, some individual, routine and organisational factors influencing the se lection of international news broadcast on SAfm's bulletins, are predetermined and co-determined by the social system (the ideological/discursive structure), which is promoted by certain social institutions. Instances of spokespersons of such institutions as governments, international governmental and non-governmental organisations, etc., officiating the news abound; the gatekeepers use them to meet routine professional standards of journalism. This potentially works to sustain the hegemonic discourses of the powerful in international affairs (in tenns of core/peripheral nations relations, and elite classlruled majority relations) though there is a conscious oppositional effort to modify or dwarf stories that explicitly promote imperialism and to hold rulers accountable to the public. It is posited that the time is ripe for newsworkers responsible for the production of bulletins for SAfm to take the risk that may be necessary to inject a few changes in routine practices that could limit the engineering of consent to the powerful elites in the international arena.
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- Date Issued: 2007
Severe convective storm risk in the Eastern Cape Province of South Africa
- Authors: Pyle, Desmond Mark
- Date: 2007
- Subjects: Storms -- South Africa -- Eastern Cape Natural disasters -- South Africa -- Eastern Cape Disasters -- South Africa -- Eastern Cape Disaster relief -- South Africa -- Eastern Cape -- Management Meteorology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4853 , http://hdl.handle.net/10962/d1005529
- Description: This study investigates the temporal, spatial and impact characteristics of severe convective storm hazard and risk in the Eastern Cape Province of South Africa. Using historical data on severe convective storms dating from 1897, patterns of the hazard threat and risk to various geographic populations were investigated. A conceptual framework that emphasises the combined role hazard and vulnerability play in defining risk was used for the study. A methodology for ranking the severity of the storms in the historical dataset, based on recorded damage/impact, was specifically developed for the study. It is intended that this methodology will have a potentially wider application and may be adapted to a range of hazard impact and risk studies in South Africa and internationally. The study was undertaken within the context of the South African Disaster Management Act of 2002. Findings of the study show that severe convective storms can occur throughout the province, but there are clearly demarcated areas of higher frequency and concentration. The impact of storms is particularly severe on impoverished and vulnerable rural populations in the eastern parts of the province, where there is an urgent need for building capacity in disaster risk management. A major outcome of the study is the production of a severe convective storm hazard/risk map of the Eastern Cape, which it is hoped will be of benefit to a number of stakeholders in the province, particularly disaster management, but also the South African Weather Service, agricultural organisations, development/planning authorities, educational authorities and risk insurers. It is hoped that this map and the study in general will assist in guiding the operational responses of the various authorities, especially in terms of those interventions aimed at disaster risk reduction in the Eastern Cape.
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- Date Issued: 2007
Social learning processes in a citrus farming community of practice
- Authors: Downsborough, Linda
- Date: 2007
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1878 , http://hdl.handle.net/10962/d1005859
- Description: Learning takes place in a number of ways. Situated learning for example, tries to shift the focus from the individual as a learner to the learner participating in the social world and from learning as a strictly cognitive process to a more encompassing view of social practice. The overall aim of this research was to gain a deeper understanding of the ways in which learning takes place in and between members of a citrus farming community, in other words it was to investigate the social learning processes. The research was undertaken in Patensie, a citrus farming community of the Gamtoos River Valley, Eastern Cape, South Africa. Data was generated through the use of interviews and informal discussions with participants together with document analysis, such as minutes of meetings. I also made observations of the learning interactions that were evident and also the interactions that were evident in the area as a whole. The data was analysed in two phases, the first involved reading across the interview transcripts and organizing the data under broad themes while the second phase made use of an analytical framework, a Community of Practice perspective to further analyze and engage with the data. I drew quite strongly on the ideas of situated learning, Communities of Practice and the notion of Legitimate Peripheral Participation (Lave & Wenger, 1991) as a means to understand, interpret and describe the social learning processes. The research highlighted that in this case study, citrus farmers learn in a number of sociological ways, for example through intergenerational learning (in the family), learning from each other in a Community of Practice, learning from private consultants and extensions officers as well as from other organizations and institutions. It also considered how farmers' learning had influenced land use practice in the area. This brought to the fore an emerging partnership with a conservation agent based on providing economic incentives to farmers to engage in sustainable landuse practices. It is hoped that this research may inform future educational endeavours by shedding light on the social learning processes and by drawing attention to key aspects of learning that may previously have been overlooked in research.
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- Date Issued: 2007
Spermiogenesis, sperm ultrastructure and reproductive tract morphology in cicadas implications for systematic relationships
- Authors: Chawanji, Abraham Simbarashe
- Date: 2007
- Subjects: Cicadas Cicadas -- Reproduction Spermiogenesis in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5770 , http://hdl.handle.net/10962/d1005458
- Description: Sperm structure in five species of cicadine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis, P. hirtipennis and Pycna semiclara) and five species of cicadettine cicadas (Melampsalta leucoptera, Quintilia walkeri, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) was investigated by light and electron microscopy. In addition, spermiogenesis in cicadas was described; the information was derived from two cicadettines (Diceroprocta biconica and M. matoposa) and three cicadines (Kongota punctigera, P. capensis and P. semiclara). Mature spermatozoa of all species investigated are elongate and filiform, consisting of three distinct regions: the head (acrosome and nucleus), mid-piece and tail. All species produce more than one discrete length of nucleated, motile sperm, a form of sperm polymorphism termed polymegaly. Polymegaly is expressed in three ways; sperm have uni-, bi- or trimodal nucleus and tail lengths. Besides the differences in length, there are also notable differences in the size of nuclei. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming spermatodesmata. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with a tubular substructure and a subacrosomal space. The anterior of the nucleus intrudes into the posterior section of the subacrosomal space. Anteriorly the acrosome is laterally flattened; posteriorly it extends as two tubular processes on either side of the nucleus that gradually decrease in diameter. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the putative centriolar adjunct which does not form in close proximity to the centriole and hence may not be a true centriolar adjunct. The lamellate disposition of the centriolar adjunct material within the sperm-midpiece of cicadettine cicadas is distinct, and separates these cicadas from their cicadine counterparts in which the centriolar adjunct material is non-lamellate. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. Except for size the architecture of short and long spermatozoa is generally similar in all species. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely related. Only long nuclei were observed in the fertilized eggs of A. zuluensis indicating that sperm with long nuclei might be favoured for fertilization. Spermiogenesis involves: (a) development of the acrosome from a proacrosomal granule; (b) development of the nucleus, characterized by elongation and streamlining with a simultaneous condensation of chromatin; (c) development of the axoneme from the centriole; (d) amalgamation of individual small mitochondria to form elongated mitochondrial derivatives in which cristae are arranged into regularly spaced lamellae; and (f) elimination of cytoplasm. The presence of a manchette, a transient microtubular organelle, which surrounds the acrosome, nucleus and mitochondrial derivatives, is a characteristic feature of spermiogenesis. The gross morphology of the reproductive tract in both male and female cicadas exhibits an organization similar to that in most oviparous insects. The non-functional spermatheca is the only exceptional feature in the female reproductive tract. Its role has been taken over by the common oviduct which, subsequently, has become modified into a swollen, differentiated structure with a dual role of receiving oocytes from the paired ovaries and storage of spermatozoa. Testis mass varies between cicada species; this variation might be linked to the intensity of sperm competition which has been found to be positively correlated with relative investment in spermatogenesis. Based on the preliminary findings of this study, K. punctigera, with its larger testis relative to body size, would be the ideal candidate to show the greatest levels of sperm competition. Accessory glands in both male and female A. zuluensis, D. biconica, P. hirtipennis and O. quadraticollis are very long; this character might be of phylogenetic significance. Despite being notoriously refractory spermiocladistics is potentially valuable in systematic and phylogenic studies of cicadas, especially at the subfamily level.
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- Date Issued: 2007
Stakeholders' perceptions of parents' involvement in the governance of a Namibian rural school
- Authors: Niitembu, Martha M
- Date: 2007
- Subjects: School management and organization -- Namibia Education -- Parent participation -- Namibia Education and state -- Namibia Rural schools -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1770 , http://hdl.handle.net/10962/d1003655
- Description: The issue of decentralisation has been one of the top priorities of the Namibian education system since independence in 1990. One of the decentralisation aims was to enhance parental involvement in education by establishing School Boards. However, School Boards and the role of parents in school management have been considered ineffective for several years which led to the promulgation of Education Act 16 of 2001 in which the roles of School Boards are strengthened and clarified. This study sought to investigate School Board members’ perceptions, understanding and experiences of parents’ involvement in school governance more specifically after the implementation of the Education Act of 2001 in 2003. This study is an interpretive case study of one combined rural school in the Ohangwena educational region of Namibia. This research employed three data collection techniques, namely semi-structured interviews, observation and document analysis. The main findings of this study reveal that there is a lack of joint understanding and shared vision between educators and parents in the School Board. This problem underpins other more symptomatic problems, such as lack of accountability in the matter of school finances, differences in understanding the roles of School Board members and lack of parents’ motivation from the school management. The study further reveals the ineffectiveness and insufficiency of the training provided in the past. It highlights some of the challenges that hinder the effective involvement of parents in rural school governance, such as poor educational background among parents, poor knowledge of the English language and poor understanding of educational issues. However the findings also acknowledge parents’ participation and their full involvement in decision-making. The findings show that the new School Board elected in terms of the Education Act of 2001 has been more effective than previous School Boards and has reached a number of achievements such as being instrumental in solving disciplinary problems, purchasing school assets and renovating classrooms. Recommendations for practice and for further research are made.
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- Date Issued: 2007
Statistical analyses of artificial waterpoints: their effect on the herbaceous and woody structure composition within the Kruger National Park
- Authors: Goodall, Victoria Lucy
- Date: 2007
- Subjects: South African National Parks , Ecology -- Statistical methods , Regression analysis , Log-linear models , Game reserves -- South Africa , Kruger National Park (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5570 , http://hdl.handle.net/10962/d1002810 , South African National Parks , Ecology -- Statistical methods , Regression analysis , Log-linear models , Game reserves -- South Africa , Kruger National Park (South Africa)
- Description: The objective of this project is to link the statistical theory used in the ecological sciences with an actual project that was developed for the South African National Parks Scientific Services. It investigates the changes that have occurred in the herbaceous and woody structure due to the closure of artificial waterpoints; including the impacts that elephants and other herbivores have on the vegetation of the Kruger National Park. This project was designed in conjunction with South African National Parks (SANP) Scientific Services and it is a registered project with this department. The results of this project will be submitted to Scientific Services in accordance with the terms and conditions of a SANP research project. A major concern within the KNP is the declining numbers of rare antelope and numerous projects have been developed to investigate possible ways of halting this decline and thus protecting the heterogeneity of the Kruger National Park. Three different datasets were investigated, covering three aspects of vegetation structure and composition within the KNP. The first investigated the changes that have occurred since the N'washitsumbe enclosure in the Far Northern KNP was fenced off from the rest of the park. The results show that over the 40 years since the enclosure was built, changes have occurred which have resulted in a significant difference in the abundance of Increaser 2 and Decreaser grass species between the inside and the outside of the enclosure. Increaser 2 and Decreaser categories are the result of a grass species classification depending on whether the species thrives or is depressed by heavy grazing. The difference in grass species composition and structure between the inside and the outside of the enclosure indicates that the grazing animals within the KNP have influenced the grass composition in a way that favours the dominant animals. This has resulted in a declining roan antelope population - one of the species that is considered as a 'rare antelope'. Many artificial waterpoints (boreholes and dams) have also been closed throughout the KNP in the hope of resulting in a change in vegetation structure and composition in favour of the roan. Veld condition assessment data for 87 boreholes throughout the Park was analyzed to determine whether the veld in the vicinity is beginning to change towards a more Decreaser dominated sward which would favour the roan. The results were analyzed for the different regions of the Park; and they indicate that changes are becoming evident; however, the results are not particularly conclusive, yet. The majority of the boreholes were closed between 1994 and 1998 which means that not a lot of data were available to be analyzed. A similar study conducted in another 10 years time might reveal more meaningful results. However the results are moving in the direction hoped for by the management of the KNP. The results show that the grass composition has a higher proportion of Decreaser grasses since the closure of the waterpoints, and the grass biomass around these areas has also improved. The results were analyzed on an individual basis; and then on a regional basis as the minimal data meant that the individual analyses did not provide any significant results. A third study was then done on the impact that the rapidly increasing elephant population on the vegetation within the Riparian zone along three rivers in the Far Northern region of the KNP. The riparian zone is an important part of the landscape, in terms of providing food for many animals as well as shade. The elephant population has increased substantially since the termination of the culling program and this means that the feeding requirements of the population has increased which could result in severe damage upon the vegetation, as elephants can be very destructive feeders. The results show surprising differences between the three years of data that were analyzed; however the results indicate that the elephants are targeting specific height ranges of trees when feeding; however they do not seem to consistently target specific tree species. This is positive for the diversity of the Riparian zone as this region is very important both ecologically and aesthetically for the tourists who visit the Park.
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- Date Issued: 2007
Studies towards the development of novel multidentate ligands
- Authors: Magqi, Nceba
- Date: 2007
- Subjects: Density functionals , Ligands , Ligands -- Design , Ligands -- Analysis , Camphor
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4358 , http://hdl.handle.net/10962/d1005023 , Density functionals , Ligands , Ligands -- Design , Ligands -- Analysis , Camphor
- Description: In this study, attention has been given to the design and synthesis of novel multidentate ligands for use in the construction of ruthenium-based metathesis catalysts, and their chelating potential has been explored by computer modelling at the Density Functional Theory (DFT) level. Both Kemp’s triacid (1,3,5-trimethyl-1,3,5-cyclohexanetricarboxylic acid) and D-(+)-camphor have been investigated as molecular scaffolds for the development of such ligands. However selective elaboration of the functional groups in Kemp’s triacid proved difficult to achieve, and the research has focused on the development of camphor derivatives. The synthesis of the camphor-based ligands has involved C-8 functionalisation and ring-opening of the bicyclic system to afford tridentate products. The formation of 9-iodocamphorquinone bis(ethylene ketal) together with the desired product, the 8-iodo isomer, has been confirmed by single crystal X-ray analysis of both compounds. Formation of the 9-iodo analogue has provided new insights into the intramolecular rearrangement of camphor skeleton, and the mechanistic implications have been assessed by coset analysis. Attempts to effect nucleophilic displacement of the 8-halogeno groups by nucleophilic donor moieties proved unexpectedly difficult and, coupled with the susceptibility of the carbonyl groups to nucleophilic attack, has led to the formation of novel tricyclic products, viz., 1,6-dimethyl-3-(2-pyridylamino)-4-oxatricyclo[4.3.0.0[superscript 3,7]]-2-nonanone and 6,7-dimethyl-3-(2-pyridylamino)-4-oxatricyclo -[4.3.0.0[superscript 3,7]]-2-nonanone. However the diphenylphosphine group was successfully introduced at C-8 and oxidative ring-opening of the camphor skeleton has afforded the tridentate ligands, 2-(diphenylphosphinoylmethyl)-1,2-dimethyl-1,3-cyclopentanedicarboxylic acid and 2-(diphenylphosphinoylmethyl)-1,3-bis(hydroxymethyl)1,2-dimethylcyclopentane. One- and two-dimensional NMR and, where appropriate, high-resolution MS methods have been used to characterise the products. Three [superscript 13]C NMR chemical shift prediction programmes, viz., ChemWindow and the MODGRAPH neural network and HOSE (Hierachially Ordered Spherical description of Environment), have been applied to representative compounds to assess their efficacy. While the predicted shifts correlated reasonably well with the experimental data, they proved to be insufficiently accurate to differentiate the isomeric systems examined.
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- Date Issued: 2007
Study of metallophthalocyanines attached onto pre-modified gold surfaces
- Authors: Mashazi, Philani Nkosinathi
- Date: 2007
- Subjects: Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Glucose -- Measurement
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4361 , http://hdl.handle.net/10962/d1005026 , Phthalocyanines , Electrochemistry , Electrodes, Enzyme , Glucose -- Measurement
- Description: Tetra-carboxy acid chloride phthalocyanine complexes of cobalt, iron and manganese were synthesized and characterized using spectroscopic and electrochemical techniques. These complexes were fabricated as thin films on gold electrode following a covalent immobilization and self-assembling methods. Surface electrochemical and spectroscopic characterization showed that these complexes are surface-confined species. The characterization using spectroscopic and electrochemical methods confirmed the formation of thiol and MPc SAMs on gold electrode. The electrocatalytic behaviour of the SAM modified gold electrodes was studied for the detection of L-cysteine and hydrogen peroxide. The limits of detection (LoD) for Lcysteine were of the orders of 10[superscript -7] mol.L[superscript -1] for all the MPc complexes studied and the LoD for hydrogen peroxide at cobalt phthalocyanine modified gold electrode was of the orders of 10[superscript -7]mol.L[superscript -1] for both electrocatalytic oxidation and reduction. The modification process for gold electrodes was reproducible and showed good stability, if stored in pH 4 phosphate buffer solutions and can be used over a long period of time. The cobalt phthalocyanine modified gold electrode was also investigated for the fabrication of glucose oxidase (GOx)-based biosensor and as an electron mediator between the enzyme and gold electrode. The behaviour of the enzyme modified gold electrode towards the detection of glucose was studied and the results gave a limit of detection of the orders of 10[superscript -6] mol.L[superscript -1] with low binding constant (4.8 mM) of enzyme (GOx) to substrate (glucose) referred to as Michaelis-Menten constant. The practical applications, i.e. the real sample analysis and interference studies, for the enzyme modified gold electrodes were investigated. These studies showed that the enzyme electrode is valuable and can be used for glucose detection.
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- Date Issued: 2007
Study of titanium, tantalum and chromium catalysts for use in industrial transformations
- Authors: Tau, Prudence Lerato
- Date: 2007
- Subjects: Titanium Tantalum Phthalocyanines Electrochemistry Photochemotherapy Chromium Spectrum analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4363 , http://hdl.handle.net/10962/d1005028
- Description: PART A The syntheses, spectroscopic and electrochemical characterisation of a series of titanium and tantalum phthalocyanine complexes are reported. The complexes are unsubstituted and substituted at either the peripheral or non-peripheral positions with sulphonates, aryloxy, arylthio or amino groups. The complexes mostly exhibit Qbands in the near-infrared region as well as interesting properties in different solvents. The interaction of differently sulphonated titanium and tantalum phthalocyanine complexes with methyl viologen (MV[superscript 2+]), and hence the stoichiometry and association constants are evaluated. Detailed photophysicochemical properties of the complexes were investigated and are for the first time presented with fluorescence lifetimes easily obtained from fluorescence quenching studies. The transformation of 1-hexene photocatalysed by aryloxy- and arylthio-appended complexes is also presented for the first time. The electrochemical properties of the complexes are unknown and are thus presented. Cyclic (CV) and square wave (SWV) voltammetries, chronocoulometry and spectroelectrochemistry are employed in the study of the complexes. Two oneelectron reductions and a simultaneous 4-electron reduction are observed for the unsubstituted Cl[subscript 3]TaPc. Reduction occurs first at the metal followed by ring-based processes. The tetra- and octa-substituted derivatives however exhibit peculiar electrochemical behaviour where a multi-electron transfer process occurs for complexes bearing certain substituents. For all complexes, the first two reductions are metal-based followed by ring-based processes. A comparative study of the electrocatalytic activities of the complexes towards the oxidation of nitrite is also investigated. The complexes are immobilised onto a glassy carbon electrode either by drop-dry or electropolymerisation methods. All the modified electrodes exhibit improved electrocatalytic oxidation of nitrite than the unmodified electrodes by a twoelectron mechanism producing nitrate ions. Catalytic currents are enhanced and nitrite overpotential reduced to ~ 0.60 V. Kinetic parameters are determined for all complexes and a mechanism is proposed. PART B: The syntheses and electrochemical characterisation of chromium and titanium complexes for the selective trimerisation of ethylene to 1-hexene are presented. The synthesis of the chromium complex requires simple steps while tedious steps are used for the air-sensitive titanium complex. The spectroscopic interaction of the chromium complex with the co-catalyst methylaluminoxane is investigated. The complexes are characterised by electrochemical methods such as cyclic voltammetry and spectroelectrochemistry.
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- Date Issued: 2007
Synthesis of novel coumarin derivatives as potential inhibitors of HIV-1 protease
- Authors: Rose, Nathan Rolf
- Date: 2007 , 2013-07-01
- Subjects: Coumarins , Protease Inhibitors , Heterocyclic compounds -- Derivatives , HIV infections -- Treatment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4430 , http://hdl.handle.net/10962/d1007220 , Coumarins , Protease Inhibitors , Heterocyclic compounds -- Derivatives , HIV infections -- Treatment
- Description: This research has focused on the development of novel coumann derivatives containing peptide-like side chains as potential HIV-1 protease inhibitors. The reaction of various salicylaldehyde derivatives with tert-butyl acrylate In the presence of 1,4- diazabicyclo[2.2.2]octane (DABCO) has afforded a series of Baylis-Hillman adducts in moderate yield. Cyclisation of the adducts in the presence of HCI afforded the corresponding 3-(chloromethyl)coumarin derivatives, which have been reacted with various amine hydrochlorides in the presence of Proton Sponge® to afford a series of novel 3- (aminomethyl)coumarin derivatives, which were fully characterised by NMR and HRMS methods. Various approaches to the introduction of hydroxyl or amino groups at the C-4 position of coumarin and the 3-(chloromethyl)coumarin derivatives have been explored; these have included dihydroxylation of the coumarin double bond, and the synthesis of 4- benzylaminocoumarin derivatives as potential intermediates. The Vilsmeier-Haack and Mannich reactions have also been investigated as possible methods of introducing the desired peptide-like functionality. Computer modelling of selected structures has indicated that some of the novel 3- (aminomethyl)coumarin derivatives may exhibit activity as inhibitors of HIV-1 protease. The planned enzyme inhibition assays were unfortunately precluded by the aqueous insolubility of the selected compounds. Three ¹³C NMR chemical shift algorithms, viz., Modgraph Neural Network, Modgraph HOSE and Chern Window, have been applied to selected compounds prepared in this study. The Modgraph Neural Network algorithm was found, in all cases, to provide the most accurate correlations with the experimentally-determined chemical shifts. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Date Issued: 2007
Synthesis of triprenylated toluquinone and toluhydroquinone metabolites from a marine-derived Penicillium fungus
- Authors: Scheepers, Brent Ashley
- Date: 2007
- Subjects: Penicillium , Antineoplastic agents , Marine fungi , Quinone
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4373 , http://hdl.handle.net/10962/d1005038 , Penicillium , Antineoplastic agents , Marine fungi , Quinone
- Description: This project forms part of a collaborative effort between the marine natural products chemists at Rhodes University and the medical biochemists at the University of Cape Town’s School of Medicine. Our UCT collaborators tested the cytotoxicity of a group of toluhydroquinones and toluquinones (9-15) against the oesophageal cancer cell line WHCO1 and revealed that the triprenylated toluhydroquinone 11 and it’s oxidised analogue 12 were the most active. This thesis presents an investigation into the role of the polyprenyl side-chain in the cytotoxicity of compound 11 and it’s oxidised analogue 12 by synthesizing and testing the cytotoxicity of simplified analogues of this compound. The synthesis of the two ortho-prenylated toluhydroquinone analogues 5-methyl-2-[(2'E,6'E)-3',7' -dimethyl-2',6'-octadienyl]-1,4-benzenediol (19) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-1,4-benzenediol (21) and their two ortho-prenylated toluquinone analogues, 5-methyl-2-[(2'E,6'E)-3',7'-dimethyl-2',6'-octadienyl]-2,5-cyclohexadiene-1,4-dione (20) and 5-methyl-2-[(2'E,6'E)-3',7',11'-trimethyl-2',6',10'-dodecatrienyl]-2,5-cyclohexadiene-1,4-dione (22) is described. Our initial attempts to couple geranyl bromide, farnesyl bromide and farnesal to the aromatic precursors m-cresol and 1,4-dimethoxy-2-methylbenzene using directed ortho-prenylation and phenoxide carbon-alkylation were unsuccessful. The four target analogues were eventually synthesized via the initial metal halogen exchange reaction between 1-bromo-2,5-dimethoxy-4-methylbenzene and geranyl bromide/farnesyl bromide using n-BuLi and TMEDA in ditheyl ether at 0 °C to yield 92 and 104 respectively in moderate yield. The demethylation of both compounds preceded smoothly using AgO giving the target analogues 20 and 22 in good yield (approx. 90 %). The reduction of quinones 20 and 22 with sodium dithionite gave 19 and 21 in quantitative yield. The synthesis reported here is the first regioselective synthesis of these compounds. The anti-oesophageal cancer activity of 19-22 and two commercially available non-prenylated analogues 17 and 18 were tested against WHCO1. The conclusion drawn from the anti-oesophageal cancer study was that the polyprenyl side-chain plays a negligable role in the cytotoxicity of compounds such as 11 and 9 against the oesophageal cancer cell line WHCO1.
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- Date Issued: 2007
Teacher motivation in a South African school
- Authors: Kovach, John C
- Date: 2007
- Subjects: Teacher morale -- South Africa -- Eastern Cape Teachers -- Professional ethics -- South Africa -- Eastern Cape Teacher-administrator relationships -- South Africa -- Eastern Cape Educational leadership -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1790 , http://hdl.handle.net/10962/d1003675
- Description: This study explores and attempts to shed light on what motivates teachers and how teacher motivation is affected by a principal's leadership style. The worldviews of pragmatism and critical realism were used as the basis for exploring teacher motivation in a South African school. A primary school in the Eastern Cape of South Africa was chosen for the case study. Three data gathering tools, a leadership questionnaire, teacher survey, and interviews were used to generate data on teacher motivation and the interaction between leadership style and teacher motivation. In regards to teachers, religion, social justice, and self-efficacy were all identified as motivators. The principal was strongly charismatic in her leadership and along with transformational and social justice leadership played a major role in influencing teacher behaviors. Self-determination theory was identified as helping to explain different levels of intrinsic and extrinsic motivation and thereby to better understand varying degrees of teacher motivation. There are many difficulties in South African education and around the world in general and this study is premised on the belief that if teacher motivation can be studied and advanced there will be an improvement in education and learning. This thesis was limited in its scope and ability to fully explore the different levels of ontology as outlined by the critical realist and this is identified as a possible future course of action for not only studying teacher motivation but getting to the 'heart of the matter'.
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- Date Issued: 2007
The artistic path to virtue
- Authors: Sher, Gavin
- Date: 2007
- Subjects: Aristotle -- Nicomachean ethics , Virtue , Ethics , Fiction , Narration (Rhetoric)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2732 , http://hdl.handle.net/10962/d1004370 , Aristotle -- Nicomachean ethics , Virtue , Ethics , Fiction , Narration (Rhetoric)
- Description: Most people share a strong intuition that there is much to be learned from great literature and other forms of narrative art. This intuition is, however, philosophically contentious. Plato was the first to argue against the possibility of learning anything from narrative art, but he founded a tradition that persists to the present day. I will engage in this debate in order to examine the role narratives might be able to play in acquiring virtue on Aristotle's ethical account, as it is presented in Nicomachean Ethics. I will claim that narratives have so long seemed a problematic source of learning because philosophers have traditionally approached the issue in the wrong way. They have typically tried to show how we might acquire propositional knowledge through our engagement with art, but this approach has failed because of insoluble problems involved in satisfying the justification criterion. Fictions may be rescued from their problematic status by realising that what we truly get from them is, instead, a type of knowledge-how. I will argue that Aristotelian virtue is itself a kind of knowledge-how and so the type of learning that takes place in engaging with narratives has a role to play in its acquisition and exercise. Virtue depends on types of reasoning that are themselves kinds of knowledge-how and which are employed and improved in engaging with narrative art. These types of reasoning will be described as conceptual, emotional and imaginative understanding. I will show how each is important in relation to virtue and how each is a kind of knowledge-how that may be improved through exposure to narrative art.
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- Date Issued: 2007
The biology and systematics of South African pipefishes of the genus Syngnathus
- Authors: Mwale, Monica
- Date: 2007
- Subjects: Pipefishes -- South Africa Syngnathus -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5237 , http://hdl.handle.net/10962/d1005080
- Description: Syngnathus the most speciose genus in the family Syngnathidae is widely in the Atlantic and Eastern Pacific oceans. However, it is poorly represented in the Indian Ocean with the only two species, Syngnathus temminckii and S. watermeyeri occurring in Southern African estuaries and coastal areas. Syngnathus temminckii the most common South African pipefish has been synonymised with S. acus, as the morphological and genetic divergence between these two populations has not been documented. There is also uncertainty in the taxonomic status of S. watermeyeri, an endemic estuarine pipefish that is restricted to two Eastern Cape estuaries. The purpose of this study was therefore to compare biological, morphological and genetic variation of South African Syngnathus species among different populations/locations, and with European populations of S. acus. Sixteen meristic and ten morphometric characteristics were quantified from specimens obtained from field as well as various international natural history museum collections. Univariate (ANOVA) and multivariate (principal component analysis and discriminant analyses) analyses were used to assess morphological differences among the species. Morphometric variables were adjusted as ratios of the standard length and using an allometric procedure. ANCOVA analysis indicated significant differences between S. acus and S. temminckii for the relationships of the standard length (SL) and all morphological characters. There was no significant correlation between SL and snout length, snout depth, inter-orbital width and trunk depth for S. watermeyeri. The analyses provided evidence for distinct populations of S. acus, S. temminckii and S. watermeyeri although morphological character differentiation was greater between S. watermeyeri and the other two larger species. Although, significant differences were observed for meristic characters, pairwise comparisons did not reflect a clear pattern of variability. Most of the measured morphological characters contributed more than 70% to the morphological variation between the populations. Plot of the canonical scores for the variables resulted in the specimens clustering according to species groups and locations of S. temminckii. Sequences of 750 base pairs of the mitochondrial cytochrome gene from 11 localities were compared with published sequences of other species of Syngnathus. Phylogenetic analysis was performed using parsimony, maximum likelihood (ML) and Bayesian inference (BI). The South African species were revealed to be sister-taxa with about 6 % divergence, while S. temminckii and S. acus had about 11% sequence divergence. 20 haplotypes among 46 total specimens from the three species. Gene flow was estimated at approximately 3 migrants per generation between the two South African populations and about 1 per generation between S. temminckii and S. acus. Such strong stock structuring among presumably recently established post-Pliocene (< 2 Million years ago) populations suggests that these species are reproductively isolated. Morphological and genetic variation observed in this study combined with current knowledge of life history attributes of the South African pipefishes indicate that conservative management decisions are necessary until the patterns and extent of differentiation among populations species-wide can be investigated further. It is thus being proposed that the name of the South African population of S. acus be changed to Syngnathus temminckii (Kaup, 1856).
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- Date Issued: 2007