"Is more, less?" : insect-insect interactions in a biological control context using water hyacinth as a model
- Authors: Weyl, Philip Sebastian Richard
- Date: 2012
- Subjects: Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5724 , http://hdl.handle.net/10962/d1005410 , Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Description: Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.
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'Becoming citizens': young people making sense of citizenship on a South African community radio station youth show
- Authors: Karamagi, Sharon Benna Kyakyo
- Date: 2012
- Subjects: Citizenship -- Study and teaching -- South Africa Youth -- Social conditions Community radio -- South Africa -- Grahamstown Grahamstown (South Africa) -- Economic conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3444 , http://hdl.handle.net/10962/d1002898
- Description: This research set out to investigate the role that community radio can potentially play as a space in which young people engage with their own role as citizens and, in so doing, participate in discussions that seek to address social problems in a community divided by class, income, gender and race. The study examines how a local community radio station - Radio Grahamstown - developed a youth programme Y4Yin which the producers of the show and its audience came together to negotiate the meaning of citizenship. The study examines whether this interactive programme was able to function as something like a public sphere where in young people were able to develop a greater sense of agency, at least in the realm of citizenship. Using evidence gathered through focus group discussions with a group of young school-going leamers, interviews conducted with the producers of the show Y4Y, and drawing on Dahlgren's elaboration of a functional public sphere, the research concludes that the show provided a useful platform for Grahamstown high school students to develop their own notions of citizenship and to, at least partially and tentatively, build some 'bridges' across the vectors of socio-economic division in the town. However, the research also concludes that the Y4Y producers often failed to use a mode of address contemporary to the youth and often did not use production techniques congruent with young people's cultural tastes. This limited the programme's appeal and its potential as an enabler of discussion about notions of citizenship and as a platform for social bridging. In addition, because of the producers' control over the choice of topics put up for discussion, open interaction was more limited than could have been expected. In addition, the study also concludes that various limitations to the leamers' freedom of expression (including their fear that teachers might be listening in to the shows) inhibited the programme's role as a deliberative public sphere where issues could be aired, common ground found, and solutions discussed.
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A baculovirus-mediated expression system for the analysis of HaSV RNA packaging
- Authors: Mendes, Adriano
- Date: 2012
- Subjects: RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4025 , http://hdl.handle.net/10962/d1004085 , RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Description: The Helicoverpa armigera stunt virus (HaSV) is a member of a family of small nonenveloped (+) ssRNA insect viruses currently known as the Tetraviridae. This family is unique in terms of the T=4 quasi-symmetry of its capsid particles and the unusually narrow host range and tissue tropism. Assembly of tetraviral particles has been well characterised and involves the combination of 240 copies of a single capsid precursor protein (VCap) into a procapsid followed by autoproteolytic cleavage to yield the major (β) and minor (γ) capsid subunits within the mature particle. HaSV has two genomic RNAs, RNA 1 encoding the replicase and RNA 2 encoding VCap and p17, the ORF of which lies upstream of and overlaping with the 5’ end of the VCap ORF. Prior to this study, Vlok (2009) used a plasmid expression system to study RNA packaging in HaSV VLPs assembled in Spodoptera frugiperda 9 (Sf9) cells co-expressing p17 and VCap. The study showed that the p17 ORF was required for the packaging of RNA 2 during capsid assembly but it was unclear whether p17 expression was required for packaging. In addition, expression from the transfected plasmids was sub-optimal affecting both the yield of VLPs and the detection of p17. The aim of this study was to use the plasmid system to test whether p17 expression was required for plasmid-derived VLP RNA packaging and then develop a baculovirus-mediated system to test this hypothesis. By using a plasmid in which the start codon of p17 was mutated, it was shown that p17 expression was required for RNA 2 packaging into plasmid-VLPs. For the baculovirus system, four recombinant baculoviruses based upon the pFastBac Dual expression system, were constructed. These included Bac20, expressing wild type RNA 2, Bac21, RNA 2 with p17 silenced, Bac23, RNA 2 and p17 expressed on a separate transcript and Bac24, RNA 2 with p17 silenced plus p17 expressed on a separate transcript. Assembly of VLPs was more efficient using the baculovirus expression system and p17 expression was observed in cells infected with Bac20, Bac23 and Bac24, but not Bac21. In contrast to the plasmid-VLPs, bac-VLPs did not require p17 for the encapsidation of RNA 2. In addition to RNA 2, Bac23 and Bac24 packaged the p17 mRNA transcribed separately from RNA 2. This insinuated that bac-VLPs may be packaging RNA non-selectively. It was proposed that p17 may play a role in packaging in an RNA-limiting environment (plasmid system) but functioned differently when viral RNA was in excess (baculovirus system). This data points to the importance of developing a replication system for the analysis of the packaging pathways of these viruses and this study has laid down the foundations for such a system in which RNA 1 and RNA 2 can be introduced into a single cell by means of a single recombinant virus.
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A case study describing factors perceived to be impacting staff satisfaction amongst health care professionals at the East London Hospital complex
- Authors: Galo, Luntu
- Date: 2012
- Subjects: Medical personnel -- Job satisfaction -- South Africa -- Case studies Medical personnel -- Job stress -- South Africa -- Case studies Medical personnel -- South Africa -- Attitudes -- Case studies Hospitals -- South Africa -- Administration Health services administration -- South Africa Health planning -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:784 , http://hdl.handle.net/10962/d1003905
- Description: This thesis was born from a concern the researcher had with regard to negative reports in the media emanating from 4 babies that died at Cecilia Makiwane Hospital Peadiatric ICU unit due to power supply failure. The most significant of these negative reports was in 2007 when the Daily Dispatch ran a series of articles regarding what they termed avoidable deaths over the last 14 years. The ease with which staff communicated with the media together with the high absenteeism rate and high turnover was a cause for concern. When the researcher analysed the history of the problem, it immerged from the respondents’ responses that the rationalistion process undertaken by the Eastern Cape Department of Health (ECDoH) was a significant root cause to the problem. The literature review focused on three areas viz.: Organisational Culture, Organisational Change, Foundations of Satisfaction. This focus was used to confine the problem to a manageable project but secondly each of the aspects are interwoven. Routledge (2010) notes that culture is the reflection of the values advocated by a founder or leader by way of his/her day to day actions. This is done by the leader creating a perception or viewpoint that assists the employees to achieve the organisation’s mission, vision and goals. In any organisation change is a constant and it needs to be effectively managed. With government institutions like the East London Hospital Complex (ELHC) directives come from the top and are implemented by an unprepared and untrained leadership and management cadre and clear communication of vision and objective of the desired outcomes never happens. The aim of the research was to: describe the existing Organisational Culture present at ELHC (Perform an organisational diagnosis); describe the impact of change (rationalisation) and to analyze why there was such a high staff turnover. It is clear from the results of the survey conducted that significant dissatisfaction prevailed relating to how the institution was managed. Dissatisfaction amongst the health professionals was general but also specific to the following: leadership and management issues, fairness, remuneration and lack of resources. The recommendations therefore focused on developing management and leadership within the proposal of Dubrin’s model (2001).
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A case study of Bigodi Wetland Sanctuary as a community driven Community-Based Natural Resource Management initiative : maintaining livelihoods and wetland health
- Authors: Gosling, Amanda Karen
- Date: 2012
- Subjects: Wetland conservation -- Uganda , Wetland ecology -- Uganda , Natural resources management areas -- Uganda , Rural development -- Uganda
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4752 , http://hdl.handle.net/10962/d1007065 , Wetland conservation -- Uganda , Wetland ecology -- Uganda , Natural resources management areas -- Uganda , Rural development -- Uganda
- Description: Community-Based Natural Resource Management (CBNRM) is considered a win-win approach to reconcile conservation with natural resource use. CBNRM aims to accomplish conservation whilst prioritising development and contributing to poverty alleviation. This study analysed the different components of a CBNRM initiative, Bigodi Wetland Sanctuary (BWS), located in western Uganda. The study was carried out by interviewing the managing committee members (n= 8) as well as local households (n= 68) regarding the manner in which the project works, and the associated benefits and constraints. The main management issues recognised were a lack of monitoring and committee cohesiveness. The information gathered through the household survey enabled the calculation of the value of local livelihood options. This was done on the premise that conservation is better accepted when land users realise the economic value of natural resources. The average annual value of household livelihoods was represented by 30% crop production, 57% natural resource use, and 13% livestock. Lastly, wetland assessments were performed using the WET-Health and WET-EcoServices methodologies from the Wetland Management Series. These assessments indicated that the impacts of local livelihoods on the wetland were currently low but potential issues could arise with the increasing human population density. Ultimately, BWS presents both environmental and social costs and benefits. With a detailed and interdisciplinary method specific recommendations of improvement can be made to reduce such costs and further reconcile the conservation of Bigodi Wetland with local natural resource use..
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A comparative polarimetric study of the 43 GHz and 86 GHz SiO masers toward the supergiant star VY CMa
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
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A critical realist exploration of the implementation of a new curriculum in Swaziland
- Authors: Pereira, Liphie
- Date: 2012
- Subjects: Critical realism Education -- Philosophy Critical pedagogy -- Swaziland Curriculum change -- Swaziland Education -- Swaziland Education and state -- Swaziland Education -- Aims and objectives -- Swaziland Critical discourse analysis International General Certificate of Secondary Education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1484 , http://hdl.handle.net/10962/d1003365
- Description: This study offers an in-depth exploration of the conditions from which the implementation of a curriculum called the International General Certificate of Secondary Education (IGCSE), later localised into Swaziland General Certificate of Secondary Education (SGCSE), emerged and the constraining and enabling conditions for the implementation of the new I/SGCSE curriculum. It derives its theoretical foundation from Roy Bhaskar’s critical realism and Margaret Archer’s concept of analytical separability. The study therefore offers explanations about the curriculum change and its implementation that are based on how structural, cultural, and agential mechanisms operating at a deeper level of reality (the intransitive layer of reality or the domain of the real) and existing independently of what we see, know or believe of them (the transitive layer of reality or domains of the actual and empirical) interacted to condition the emergence of I/SGCSE and the way it is implemented. I conduct a critical discourse analysis of relevant literature, I/SGCSE documents and interview data in order to identify those mechanisms that were cultural and also those that were structural and agential. Bernstein’s concepts of classification and framing are used to analyse observation data in order to explore the influence of these mechanisms on the teaching practices of the teachers who took part in the study. Analysis of the data suggests that the change from General Certificate of Education Ordinary Level (GCE O-level) to I/SGCSE was conditioned by inconsistencies between the cultural and structural mechanisms of the Swazi context. Many of the cultural elements of the Swazi context such as the discourses of good citizens, of competitive advantage, and of quality education draw from global discourses which view relations between people from a postmodernist position and therefore support weakly classified and framed pedagogic practices. In contrast, the discourse of morality and many of the structural elements of the Swazi context, such as the pre2006 education system and the Tinkhundla government system, all view reality from a modernist position, therefore supporting strong relations of power and control. The cultural system therefore exerted more influence in conditioning the change from the strongly classified and framed GCE O-level curriculum to the weakly classified and framed I/SGCSE curriculum. Furthermore, the analysis of interview and observation data suggests that inconsistencies between the global discourses and the discourses and structures that teachers confront in their day-to-day lives, together with the decisions teachers made in response to structural constraints, created constraining conditions for the change from GCE O-level to I/SGCSE. The study adds to knowledge on curriculum change and implementation through insights into the enabling and constraining effects of mechanisms operating at a deeper level of reality on curriculum-change decisions and on the ability of teachers to implement curriculum changes. The focus on the deeper level of reality may therefore contribute towards emancipatory knowledge which could be used not only by the Ministry of Education and Training and teachers in Swaziland but also elsewhere to inform future planning, decision making, and practice in relation to curriculum change and implementation.
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A framework for the development and measurement of agile enterprise architecture
- Authors: Mthupha, Bokang
- Date: 2012
- Subjects: Management information systems -- Research Industrial management -- Technological innovations -- Research Industrial organization -- Technological innovations -- Research System design
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1147 , http://hdl.handle.net/10962/d1002777
- Description: Enterprise architecture is the high-level design of the entire business, facilitated by enterprise architects. "Agile enterprise architecture" is the term used in enterprise architecture to describe an architecture that caters for future unknowns, enabling change to occur rapidly without undue resource utilization, yet in a controlled manner and with minimal adverse impact. Some enterprise architects still use outdated, rigid approaches to enterprise architecture which are incompatible with today‟s business environment. In addition, there is limited research into methods that can be applied to measure the agility of enterprise architecture. The current environment is such that there is a need for a more agile approach to developing and measuring enterprise architecture. This work will lead to the creation of a Framework for The Development and Measurement of Agile Enterprise Architecture. In support of the main goal of the development of the framework, a literature review will be conducted focusing on the necessary sub-goals of the research. The first sub-goal of the literature review is to develop a comprehensive definition for enterprise architecture (referred to as EA), as well as discover how it is currently practiced. Thereafter, the literature review will investigate a comprehensive definition for agility and research why it is emerging as a critical topic. The next chapter of the literature review will research how agility fits within the context of EA, uncovering a comprehensive definition for agile EA and the best practices in agile EA development. The final chapter of the literature review will investigate suitable measurement techniques that can be used to assess the level of agility of EA. On completion of the literature review, a preliminary framework will be created using the most important contributions from the literature. An empirical study will be conducted to explore the definitions for EA, agility, agile EA, the methods to measure the agility of EA and the concepts for the development of agile EA summarised in the preliminary framework. Data analysis follows an interpretive and qualitative approach based on four case studies through interviews with systems experts in four South African organizations in one province. Each interviewee was interviewed once. The initial interview with a Principal Consultant on Enterprise Strategy Consulting at organisation # 1 formed the basis of an exploratory study; the results of which were used to refine the research instrument and preliminary framework. Thereafter, a more rigorous empirical study focused on interviews with the Chief Architect, Senior Manager in Advisory Services and an Enterprise Architect at organizations 2, 3 and 4 respectively was conducted. The research follows an inductive approach to capture the interpretive experiences of participants and develop theoretical propositions from them. Following the exploratory pilot study it became necessary to make changes to the preliminary framework and initial survey instrument created. Thereafter, the empirical study consisting of the remaining three cases was conducted to test the important aspects of the framework and literature definitions. The analysis of the results of the empirical study prompted further changes to the theoretical framework and definitions created. The interviews conducted with each of the organizations confirmed the factors for agile EA development as well as the effectiveness of the definitions created in the literature review. The research uncovered that the need for a more agile approach to developing EA and a way to measure the level of agility of EA has become more and more significant in organizations. This begins with a better understanding of EA, agility, how agility fits within the context of EA, as well as appropriate methods to measure agility.
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A process-genre approach to teaching argumentative writing to grade nine learners
- Authors: Elson, Jillian Margaret
- Date: 2012
- Subjects: English language -- Rhetoric -- Study and teaching (Secondary) English language -- Writing -- Study and teaching (Secondary) Written communication
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1714 , http://hdl.handle.net/10962/d1003597
- Description: This action research study aimed to improve teaching and learning of argumentative writing through a process-genre approach. Learners were carefully guided through the processes of writing the argumentative genre, with the focus being on teaching of the genre and on the structural conventions of writing arguments. Participants were a class of grade nine learners who speak English as a first language. They were chosen for this study as Grade Nine is a crucial year for writing development before learners enter the senior phase and are met with heightened expectations in the curriculum, that often they struggle to meet, as their writing has not been sufficiently developed to an academic level. The focus of writing in Grade Nine is on narrative and prose, so this writing intervention, in which a teaching module was developed in collaboration with the 1eamers, aimed to broaden their writing skills and provide them with a head start in leaming the fine art of argumentation, as this is a useful skill to acquire for purposes even beyond the classroom. Genre theorists advocate the importance of teaching genres to leamers at a young age, as it allows them access into different communities of discourse, as they become aware and understand the conventions held by a patiicular community, and realize the purpose of different styles of writing for effectively communicating, which prepares them to meet the expectations of their audience. Teaching the structures of different genres therefore allows the writer, and the audience, a framework for understanding the text. The process approach has been widely used by educators as it focuses on explicit teaching of writing processes that are fundamental to leamers' development in writing. Learners need to be carefully guided from the initial stages, to the more complex stages (especially in argumentative writing which has been deemed the most complex genre for learners to master) in order to understand the complexities of constructing an essay in a cohesive way, as they need to consider multiple aspects of writing, such as the linguistic features, rhetorical features and structural features of the genre and unify them into a sound argument. This takes time, practice and revision, and extensive feedback is required. The process-genre approach proved to be successful in this study, as leamers showed remarkable improvements in their writing from the initial stages of writing to the final drafts of their essays. The findings revealed that explicit teaching of genres and structural elements of writing is vital for ensuring learners' development. Learners require modelling of the genre, scaffolding and careful guidance through step-by-step processes in order to build confidence and express their ideas effectively in written text. The findings indicate the relevance of using the process-genre approach for teaching and learning and that teaching and learning writing is indeed a process that needs more time and practice that is cUiTently allocated in the curriculum.
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A South African perspective on the tax implications of virtual asset accumulation and transactions stemming from persistent virtual worlds
- Authors: Haupt, Alexander
- Date: 2012
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:884 , http://hdl.handle.net/10962/d1001638
- Description: Massively multiplayer online role-playing games are growing in popularity with millions of people participating in these persistent online environments on a daily basis. Accompanying the ever-increasing subscription numbers is an increase in real money trade transactions stemming from these game worlds. The research question to be addressed in this thesis is whether transactions stemming from virtual worlds have real-world taxation consequences. The goal of this research is to determine the taxability of virtual assets obtained in structured as well as unstructured virtual environments and to attempt to establish the differences between capital and revenue receipts in these virtual realms, taking into account the nature of a receipt. The general deduction formula is applied to establish the deductibility of expenditure incurred whilst participating in these virtual environments. Sundry matters such as Value-Added Tax, donations tax, the withholding tax on gambling gains and tax avoidance will also be addressed. The methodology adopted for the research could best be described as interpretative, aimed at analysing and interpreting the relationship between real world taxes and persistent virtual worlds and the transactions that stem from participation therein. The research is based purely on documentary evidence. After applying relevant tax legislation to virtual economies it became evident that merely because virtual assets only exist in virtual reality does not necessarily preclude them real world tax consequences. It was concluded, however, that it is not practical for the South African Revenue Service to monitor all virtual world transactions or for participant taxpayers to calculate the real world value of each and every asset acquired in-world. As a result, it was concluded that real world tax consequences should only be applied in situations where participants actually convert their virtual assets into real world currency.
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A spatial and temporal analysis of the changes in alien macrophyte communities and a baseline assessment of the macroinvertebrates associated with Eurasian watermilfoil, Myriophyllum spicatum L. (Haloragaceae) in the Vaal River
- Authors: Fordham, Colin Justin
- Date: 2012
- Subjects: Water hyacinth -- Control -- South Africa , Aquatic weeds -- Control -- South Africa , Eurasian watermilfoil -- South Africa , Water quality management -- South Africa , Freshwater invertebrates -- Ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5767 , http://hdl.handle.net/10962/d1005455 , Water hyacinth -- Control -- South Africa , Aquatic weeds -- Control -- South Africa , Eurasian watermilfoil -- South Africa , Water quality management -- South Africa , Freshwater invertebrates -- Ecology -- South Africa
- Description: The majority of South Africa’s fresh water (lotic and lentic), is eutrophic and this has resulted in water hyacinth, Eichhornia crassipes (C.Mart.) Solms. (Pontederiaceae) becoming South Africa’s most damaging aquatic macrophyte. Recently however, concerns have also been voiced over the presence of highly invasive submerged macrophyte species, such as Eurasian water-milfoil, Myriophyllum spicatum L. (Haloragaceae) in the Vaal River. Interaction studies between floating and submerged macrophytes have shown that floating macrophyte dominance restricts light penetration into the water column shading out submerged macrophytes while submerged macrophyte dominance reduces nutrient availability in the water column limiting floating macrophyte growth. This cycle ensures that these species cannot coexist in the same habitat for extended periods of time. The aims of this thesis were to: 1. Investigate changes in the historical and current macrophyte dominance in the Vaal River 2. Determine whether these changes could be attributed to stochastic events, such as floods and herbicide control measures. 3. The physio-chemical conditions of the water column, and whether pressure from herbivory by macroinvertebrates had possibly influenced Eurasian water-milfoil’s ability to dominate. Spatial and temporal analysis of satellite imagery revealed that water hyacinth and submerged macrophyte species dominated different regions of the study area over different periods of time from 2006 to 2010. This was significantly correlated with nitrate concentrations of the water column. One of the lower Vaal River Water Management Areas (WMA) had changed from a water hyacinth dominated state in 2006 to an alternative submerged macrophyte dominated stable state in 2008. It was concluded that this change could be attributed to: a stochastic flooding event in 2006; perturbation from integrated control measures implemented against water hyacinth; and low nitrate concentrations of the WMA. The lack of any substantial macroinvertebrate herbivory pressure or control measures implemented against Eurasian water-milfoil, compared to similar surveys conducted in the U.S.A. and its native range in Eurasia was shown to contribute to its dominance. Future successful integrated control programmes, including biological control against Eurasian water-milfoil, could provide the perturbation required to restore the ecosystem. However, without the reduction in nitrate concentration levels, water hyacinth will remain the dominant stable state of the rest of the Vaal River.
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A structural and functional specification of a SCIM for service interaction management and personalisation in the IMS
- Authors: Tsietsi, Mosiuoa Jeremia
- Date: 2012
- Subjects: Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4606 , http://hdl.handle.net/10962/d1004864 , Internet Protocol multimedia subsystem , Internet Protocol multimedia subsystem -- Specifications , Long-Term Evolution (Telecommunications) , European Telecommunications Standards Institute , Wireless communication systems , Multimedia communications
- Description: The Internet Protocol Multimedia Subsystem (IMS) is a component of the 3G mobile network that has been specified by standards development organisations such as the 3GPP (3rd Generation Partnership Project) and ETSI (European Telecommunication Standards Institute). IMS seeks to guarantee that the telecommunication network of the future provides subscribers with seamless access to services across disparate networks. In order to achieve this, it defines a service architecture that hosts application servers that provide subscribers with value added services. Typically, an application server bundles all the functionality it needs to execute the services it delivers, however this view is currently being challenged. It is now thought that services should be synthesised from simple building blocks called service capabilities. This decomposition would facilitate the re-use of service capabilities across multiple services and would support the creation of new services that could not have originally been conceived. The shift from monolithic services to those built from service capabilities poses a challenge to the current service model in IMS. To accommodate this, the 3GPP has defined an entity known as a service capability interaction manager (SCIM) that would be responsible for managing the interactions between service capabilities in order to realise complex services. Some of these interactions could potentially lead to undesirable results, which the SCIM must work to avoid. As an added requirement, it is believed that the network should allow policies to be applied to network services which the SCIM should be responsible for enforcing. At the time of writing, the functional and structural architecture of the SCIM has not yet been standardised. This thesis explores the current serv ice architecture of the IMS in detail. Proposals that address the structure and functions of the SCIM are carefully compared and contrasted. This investigation leads to the presentation of key aspects of the SCIM, and provides solutions that explain how it should interact with service capabilities, manage undesirable interactions and factor user and network operator policies into its execution model. A modified design of the IMS service layer that embeds the SCIM is subsequently presented and described. The design uses existing IMS protocols and requires no change in the behaviour of the standard IMS entities. In order to develop a testbed for experimental verification of the design, the identification of suitable software platforms was required. This thesis presents some of the most popular platforms currently used by developers such as the Open IMS Core and OpenSER, as well as an open source, Java-based, multimedia communication platform called Mobicents. As a precursor to the development of the SCIM, a converged multimedia service is presented that describes how a video streaming application that is leveraged by a web portal was implemented for an IMS testbed using Mobicents components. The Mobicents SIP Servlets container was subsequently used to model an initial prototype of the SCIM, using a mUlti-component telephony service to illustrate the proposed service execution model. The design focuses on SIP-based services only, but should also work for other types of IMS application servers as well.
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A systematic revision of selected genera of afrotropical curtonotidae (Diptera: schizophora: ephydroidea) : a phylogenetic approach
- Authors: Kirk-Spriggs, Ashley H
- Date: 2012
- Subjects: Curtonotidae -- Research Diptera -- Research Flies -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5627 , http://hdl.handle.net/10962/d1004747
- Description: The first comprehensive phylogeny of the family Curtonotidae is presented based on molecular markers and morphology. This enabled assessment of evolutionary relatedness, species radiation and zoogeography. A revised classification of the world fauna of the family, based on the results of this study is outlined. Nomenclatural acts flowing from these analyses include: the recognition three new Afrotropical species of Axinota van der Wulp; four new species of a new genus, Tigrisomyia Kirk-Spriggs; and nineteen new species of Curtonotum (six Madagascan and thirteen African). Ten informal species-groups of Curtonotum are recognised. Identification keys are provided for the Afrotropical species of these genera and errors in previous interpretations and designation of type specimens are resolved. Species distributions are mapped and interpreted and discussion is made of the historical biogeographical significance of these distributions.
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Adolescents' knowledge about abortion and emergency contraception a survey study
- Authors: Seutlwadi, Lebogang
- Date: 2012
- Subjects: Birth control -- Social aspects -- South Africa -- Buffalo City Emergency contraceptives -- Social aspects -- South Africa -- Buffalo City Reproductive rights -- South Africa Teenage pregnancy -- Social aspects -- South Africa -- Buffalo City Teenage pregnancy -- Psychological aspects -- South Africa -- Buffalo City Abortion -- Social aspects -- South Africa -- Buffalo City Abortion -- Health aspects -- South Africa -- Buffalo City Abortion -- Psychological aspects -- South Africa -- Buffalo City Teenagers -- Sexual behavior -- South Africa -- Buffalo City Sex instruction for teenagers -- South Africa -- Buffalo City Health education -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3052 , http://hdl.handle.net/10962/d1002561
- Description: Adolescents have become focal points of discussions and debates regarding sexuality and reproductive health matters. However, little research has been done particularly in South Africa to examine their knowledge concerning abortion and emergency contraception. Research indicates that a substantial proportion of adolescent pregnancies are unintended or unwanted. Abortion and emergency contraception are both time-sensitive services. Thus having accurate and comprehensive knowledge about both abortion and emergency contraception is pivotal, in the case of unintended or unwanted pregnancy or when engaging in unprotected sex or experiencing contraceptive failure that could lead to pregnancy. The 1994 International Conference on Population and Development (ICPD) defined reproductive health rights for both men and women as the right to "decide freely and responsibly the number, spacing and timing of their children and to have the information and means to do so" (p. 60). That is, men and women should "have the right to make decisions concerning their reproduction free of discrimination, violence and coercion" (ICPD, 1994, p.60). Based on these definitions, it is rather evident that comprehensive and accurate knowledge are at the core of one's ability to make an informed consent. This is confirmed by Adler's (1992, p. 289) definition of informed consent or choice "a) access to sufficient information b) understanding the information c) competence to evaluate potential consequences d) freedom to make a choice and e) the ability to make and express that choice". It is from this framework that this study emerged. The aim of this study was to examine adolescents' knowledge concerning abortion and emergency contraception. The participants were Grade 11 learners between the ages of 15-24 years from five different schools in the Buffalo City Municipality. A sample of 514 was achieved. Data were analysed using descriptive cross-tabulation, chi-square and qualitative methods where appropriate. The results revealed that most of the participants did not have sufficient accurate knowledge concerning the Choice on Termination of Pregnancy Act, consequences of legal abortion and emergency contraceptive pills to make informed decisions. Furthermore, data also revealed that the participants' schools playa role in their sexual activity, their knowledge about the Choice on Termination of Pregnancy Act and about emergency contraceptive pills. Although this method made it feasible for the researcher to make general assumptions, non-responses were one of the limitations of the study. Similar research in various municipalities/cities in and outside the Eastern Cape is recommended so as to increase further awareness concerning the level of knowledge that adolescents have about contraceptive pills particularly emergency contraceptive pills, the Choice on Termination of Pregnancy Act and abortion in general.
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An analysis of ionospheric response to geomagnetic disturbances over South Africa and Antarctica
- Authors: Ngwira, Chigomezyo Mudala
- Date: 2012
- Subjects: Geomagnetism -- South Africa , Geomagnetism -- Antarctica , Ionospheric storms -- South Africa , Ionospheric storms -- Antarctica
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5534 , http://hdl.handle.net/10962/d1012957
- Description: The ionosphere is of practical importance for satellite-based communication and navigation systems due to its variable refractive nature which affects the propagation of trans-ionospheric radio signals. This thesis reports on the first attempt to investigate the mechanisms responsible for the generation of positive ionospheric storm effects over mid-latitude South Africa. The storm response on 15 May 2005 was associated with equatorward neutral winds and the passage of travelling ionospheric disturbances (TIDs). The two TIDs reported in this thesis propagated with average velocities of ∼438 m/s and ∼515 m/s respectively. The velocity of the first TID (i.e. 438 m/s) is consistent with the velocities calculated in other studies for the same storm event. In a second case study, the positive storm enhancement on both 25 and 27 July 2004 lasted for more than 7 hours, and were classified as long-duration positive ionospheric storm effects. It has been suggested that the long-duration positive storm effects could have been caused by large-scale thermospheric wind circulation and enhanced equatorward neutral winds. These processes were in turn most likely to have been driven by enhanced and sustained energy input in the high-latitude ionosphere due to Joule heating and particle energy injection. This is evident by the prolonged high-level geomagnetic activity on both 25 and 27 July. This thesis also reports on the phase scintillation investigation at the South African Antarctic polar research station during solar minimum conditions. The multi-instrument approach that was used shows that the scintillation events were associated with auroral electron precipitation and that substorms play an essential role in the production of scintillation in the high latitudes. Furthermore, the investigation reveals that external energy injection into the ionosphere is necessary for the development of high-latitude irregularities which produce scintillation. Finally, this thesis highlights inadequate data resources as one of the major shortcomings to be addressed in order to fully understand and distinguish between the various ionospheric storm drivers over the Southern Africa mid-latitude region. The results presented in this thesis on the ionospheric response during geomagnetic storms provide essential information to direct further investigation aimed at developing this emerging field of study in South Africa.
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An analysis of pacing and sequencing of reading instruction in three grade 1 classrooms where isiXhosa is the language of learning and teaching
- Authors: Masola, Athambile
- Date: 2012
- Subjects: Reading (Elementary) -- Study and teaching -- Foreign speakers -- Research -- South Africa Literacy -- Education (Primary) -- Research -- South Africa English language -- Study and teaching -- South Africa -- Foreign speakers
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1420 , http://hdl.handle.net/10962/d1003301
- Description: Reading development in the Foundation Phase (FP) is central to children’s success as they progress through school. However, evaluations in South Africa such as the Annual National Assessments (ANAs) and the Progress in International Reading Literacy Study (PIRLS) (2006) show that reading achievement in the Foundation Phase is low, especially for children learning with African languages as their home language. This thesis examines pacing and sequencing in three Grade 1 literacy classes where isiXhosa is the language of learning and teaching (LOLT). The research took the form of a case study, focusing on the teachers’ classroom practice and how they understand their practice. Documents related to reading development in the Foundation Phase are analysed with regard to pacing and sequencing, examining how the curriculum frames literacy for teachers in the Foundation Phase. The teachers’ understanding in relation to their social context is also an important part of this research. In the thesis the way in which the teachers sequence and pace learning is analysed, drawing on Bernstein’s notions of internal and external framing, and Bourdieu’s notion of the habitus. The intended curriculum and the implemented curriculum are then compared. The results confirm that in low socio‐economic status (SES) schools, the level of poverty has an impact on teaching practice. The results also show that pacing and sequencing are reliant on the degree of planning amongst teachers. The level of development amongst learners also plays a role in how teachers organise their practice in order to differentiate the teaching of reading for all learners. The understanding that teachers have about their teaching practice are layered and influenced by their experiences, history and memories as teachers. The thesis concludes that there is a need to develop teachers’ understanding of planning and organising the teaching of reading, especially when the learners are from poor communities and do not get support in the home. In order for teachers to improve their practice, it is important for them to have the opportunity to reflect on and understand their practice.
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An analysis of the determinants and recent decline of private savings in South Africa
- Authors: Linde, Kathryn Leigh
- Date: 2012
- Subjects: Saving and investment -- Research -- South Africa Finance, Personal -- Research -- South Africa Corporations -- Finance -- Research -- South Africa Economic development -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1007 , http://hdl.handle.net/10962/d1002742
- Description: Low domestic saving rates make South Africa highly dependent on foreign capital inflows to fund higher investment levels. These inflows are highly volatile and may prove to be unsustainable in the long-run. This study analyses the determinants of private saving in South Africa, with specific reference to the decline in private saving rates that occurred at a time of higher economic growth prior to the 2008 global financial crisis. The Johansen cointegration method is used to estimate separate vector error correction models (VECM) in order to assess the effect of specific variables on both corporate and household saving. The results obtained that are common to both corporate and household savmg show that the govemment budget balance negatively impacts private saving rates though the offset is less than one. The real prime overdraft rate positively impacts private saving, although the result is small . The impact of real Gross Domestic Product (GDP) is positive. In recent years, however, private saving rates fell alongside higher economic growth, which may reflect a structural change in corporate saving behaviour. The results distinct to the corporate saving model show that commodity prices have a negative impact on corporate saving. This does not conform to a priori expectations, but is supported by the behaviour of these two variables in recent years. Foreign savings were found to impact negatively on corporate saving. This result is important, since the dependence of the South African economy on foreign capital inflows to fund higher investment levels is reflected by high current account deficits during recent periods of economic growth. Evidence of financial liberalization negatively impacting on private saving in South Africa due to the removal of borrowing constraints was found. A negative relationship was found between corporate saving and investment demonstrating that corporations have reduced levels of retained eamings for funding investment expenditures. The results distinct to the household saving model provide evidence of a negative wealth effect in South Africa, with rising housing wealth found to increase consumption. Evidence of households "piercing the corporate veil" in South Africa was found. Therefore, households view corporate saving behaviour as essentially being conducted on their behalf. This finding and the finding that the offset between the budget deficit and private saving is less than one suggest that counter-cyclical fiscal policy will be an important policy response for achieving higher domestic saving rates in South Africa.
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An analysis of the financing mechanisms proposed for funding national health insurance in South Africa
- Authors: Stevens, Nicol Susan
- Date: 2012
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:888 , http://hdl.handle.net/10962/d1001642
- Description: In the 2011 Budget Speech, the Minister of Finance announced that South Africa would be introducing National Health Insurance. The Minister described the financing mechanisms under consideration for funding National Health Insurance. The Minister also referred to eight countries, namely Japan, South Korea, Taiwan, Chile, Colombia, Mexico, Thailand and Vietnam as examples of countries which had successfully implemented universal health coverage. These countries were selected for the purpose of the present research. The goal of this study was to analyse the health care financing mechanisms under consideration in South Africa to determine if they were in line with international trends and "best practice" in relation to South Africa's economic profile. To determine whether the economic situation in South Africa is comparable to the eight countries selected for the research, a high-level comparison was made of the economic profile of South Africa and the eight countries, based on certain demographic, macro-economic, health expenditure and health status indicators. The health care financing mechanisms used in the eight countries was also analysed. International trends suggested that health care should be financed primarily through pre-payment systems, that financing mechanisms should preferably be progressive in nature and that a large share of funding should be from government sources (albeit shared between general tax revenue and specific health care contributions). The financing mechanisms under consideration in South Africa reflect these norms. The health systems in the eight countries analysed all exhibited elements of "good performance" and also complied, to a large extent, with international trends, but the frnancing models used for funding health care in the eight countries were country-specific and could therefore not be compared directly or used to recommend a system for South Africa. Areas not addressed by this thesis include the implications of a centralised healthcare system, the implications of a single-payer system, the benefit package to be offered and its cost implications, the role of private healthcare providers and how the significant human resource scarcity and infrastructure backlogs will be addressed.
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An analysis of the impact of tax changes between 1996 and 2012 on the tax burden of individuals in South Africa
- Authors: Krug, Lee
- Date: 2012
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:885 , http://hdl.handle.net/10962/d1001639
- Description: The objective of the research was to determine whether the changes made to the Income Tax Act, 58 of 1962 between 1996 and 2012, in respect of fringe benefits, allowances, deductions, tax tables and rebates, where these changes apply to individuals, have resulted in relieving the tax burden placed on individuals in South Africa. The research was conducted by means of a critical analysis of documentary data with specific reference to the Income Tax Act, annual amendments to the Income Tax Act, statistics relating to tax collections, the National Budget and the Annual Budget Speeches as tabled by the Minister of Finance. These sources were utilised to analyse the amendments to the Act that have taken place over the last sixteen years, where they impact on the tax liability of an individual. A hypothetical example incorporating all the variables identified in the analysis of the tax amendments was used to provide a detailed analysis of the tax payable by an individual on an inflation-adjusted year-on-year basis. The research found that, whilst personal income tax is still the largest contributor to the national budget of South Africa, its contribution has decreased from 40.2 percent in 1996 to 34.3 percent in 2010. This decrease is partly attributable to the extensive tax reforms undertaken by Government with respect to the tax tables, resulting in a reduction in the marginal tax rates and increased tax rebates which had the effect that the individual taxpayer (as illustrated in the hypothetical example) experienced a decrease in the average rate of tax. In contrast to this, the increase in the taxable income of the hypothetical taxpayer exceeded the average rate of inflation over the period. Furthermore, the actual revenue collected by the government from personal income tax has increased by approximately eleven percent per annum, which far exceeds the average inflation rate of 6.23 percent. The research indicated that this could be the result of the increase in the taxable value of fringe benefits, specifically medical aid contributions and company cars, as well as the inclusion of the full amount of allowances in taxable income and the limits placed on the deductions an individual may claim. The result is a broadening of the tax base of the individual taxpayer. Therefore, although the government may have achieved its goal of a fairer tax system, the amendments made to fringe benefits, allowances and deductions have resulted in an increase in the average taxable income of individuals.
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An analysis of the Libor and Swap market models for pricing interest-rate derivatives
- Authors: Mutengwa, Tafadzwa Isaac
- Date: 2012
- Subjects: LIBOR market model , Monte Carlo method , Interest rates -- Mathematical models , Derivative securities
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5573 , http://hdl.handle.net/10962/d1005535
- Description: This thesis focuses on the non-arbitrage (fair) pricing of interest rate derivatives, in particular caplets and swaptions using the LIBOR market model (LMM) developed by Brace, Gatarek, and Musiela (1997) and Swap market model (SMM) developed Jamshidan (1997), respectively. Today, in most financial markets, interest rate derivatives are priced using the renowned Black-Scholes formula developed by Black and Scholes (1973). We present new pricing models for caplets and swaptions, which can be implemented in the financial market other than the Black-Scholes model. We theoretically construct these "new market models" and then test their practical aspects. We show that the dynamics of the LMM imply a pricing formula for caplets that has the same structure as the Black-Scholes pricing formula for a caplet that is used by market practitioners. For the SMM we also theoretically construct an arbitrage-free interest rate model that implies a pricing formula for swaptions that has the same structure as the Black-Scholes pricing formula for swaptions. We empirically compare the pricing performance of the LMM against the Black-Scholes for pricing caplets using Monte Carlo methods.
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