Historical biogeography of the tribe Platypleurini Schmidt, 1918 (Hemiptera: Cicadidae) with a focus on Southern Africa
- Authors: Price, Benjamin Wills
- Date: 2010
- Subjects: Biogeography -- History -- Africa, Southern Cicadas -- Africa, Southern Cicada (Genus) -- Africa, Southern Biodiversity -- Africa, Southern Cicadas -- Variation -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5708 , http://hdl.handle.net/10962/d1005394
- Description: With our contemporary biota under increasing threat of extinction, it is of interest to understand where, why and how biological diversity is generated. If focussed on appropriate taxa, phylogeographic and phylogenetic studies can assist in the identification of both places and processes central to the origin and maintenance of biological diversity. It is explained why southern Africa presents a perfect test-bed for exploring such mechanisms of diversification and why cicadas (Hemiptera: Cicadidae) have proved very suitable tools for studies of historical biogeography. This study then exemplifies these points by providing the first large-scale investigation of the historical biogeography of the tribe Platypleurini Schmidt, 1918, with emphasis on the genus Platypleura Amyot & Seville, 1843 in southern Africa. Standard methods of DNA sequencing provided data from portions of the mitochondrial small subunit ribosomal 16S RNA (16S) and cytochrome oxidase subunits I (COI) and II (COII); and the nuclear elongation factor 1 alpha (EF-1α) from 400 ethanol-preserved specimens. These data were analysed using standard phylogenetic methods and a time scale of diversification was estimated using a Bayesian framework and both fossil data and DNA substitution rates. The results showed that the tribe is too recent to be of Gondwanan origin. The lack of monophyly of the genera represented in both Asia and Africa showed that the tribe needs formal taxonomic revision. Diversification of the African platypleurine genera coincides with aridification in the early Oligocene. Dispersal of Asian platypleurine taxa coincides with the meeting of Africa and Eurasia in the mid-Oligocene. Two radiations within African Platypleura are hypothesised; one distributed over most of sub-Saharan Africa and the second restricted to southern Africa, with clades restricted within regional biomes. Within each of the three focal biomes, cryptic taxonomic diversity was confirmed, suggesting that, even in relatively well understood groups such as the southern African platypleurine cicadas, molecular data can identify further diversity. Although each focal taxon was restricted to non-overlapping biomes, comparison of the three biomes highlighted interactions between palaeoclimates and fixed landscape features (coastal topography, river catchments and escarpments) as causative agents of vicariance, dispersal, extinction and diversification of these volant insects. The results of using co-distributed species for comparative study cautions against making inferences based on single-taxon datasets and highlights the need to use many, evolutionarily independent taxa when identifying mechanisms of diversification. The dating analyses imply that within-species lineage diversification occurred overwhelmingly within the Pleistocene, a trend that is being increasingly recognised in print for other biota. Some caveats about using phylogenetic approaches to estimate ancestral areas are illustrated. Several recommendations are made regarding additional taxa and data sources for understanding the origin and maintenance of biological diversity.
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- Date Issued: 2010
Rethinking South Africa's small-scale fisheries management paradigm and governance approach : evidence from the Eastern Cape
- Authors: Raemaekers, Serge
- Date: 2010
- Subjects: Fishery management -- South Africa -- Eastern Cape -- Case studies Fishery policy -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- Economic aspects -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- Social aspects -- South Africa -- Eastern Cape -- Case studies Small-scale fisheries -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5202 , http://hdl.handle.net/10962/d1003921
- Description: This thesis presents a first analysis of how the South African fisheries authority (MCM) has utilised its fisheries management toolbox and governance framework in response to the emerging biological, economic and social challenges of post-apartheid fisheries in the Eastern Cape Province. Despite recognition of the socio-economic circumstances of traditional subsistence fishers in the region, the national fisheries management authority implemented a 'target resource orientated' management approach similar to that used for South Africa's rights-based commercial fisheries. Anecdotal evidence of entrenched illegal fishing for abalone, spiny lobster, and species targeted by subsistence fishers however suggested that MCM's management approach was encountering serious problems, as the needs and circumstances of inshore fishers and fishing communities were not adequately being understood and addressed. A review of fisheries management literature therefore shaped the hypothesis that an underlying governance problem was responsible for the symptoms of management failure being observed. In this regard, management is seen as more concerned with the technical and regulatory measures of the day-to-day operations of regulated fisheries, while fisheries governance needs to take account of "the sum of legal, social, economic and political arrangements used to manage fisheries ... ". Thus, governance includes policy making and management decision-making, with simultaneous recognition of issues outside of the fisheries sector. It thus appeared that the underlying problem was rather one of broader fisheries governance and inappropriate governance objectives with consequent inappropriate resource management arrangements. This thesis set out to gather evidence to test this hypothesis.
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- Date Issued: 2010
The adoption of quality assurance in e-Health acquisition for rural hospitals in the Eastern Cape Province
- Authors: Ruxwana, Nkqubela
- Date: 2010
- Subjects: Quality assurance -- Management , Hospital care -- Quality control , Health facilities -- Quality control , Health -- Computer network resources , Public health -- Information services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9731 , http://hdl.handle.net/10948/1514 , Quality assurance -- Management , Hospital care -- Quality control , Health facilities -- Quality control , Health -- Computer network resources , Public health -- Information services
- Description: The evolution of e-health has the potential to assist in the management of scarce resources and the shortage of skills, enhance efficiencies, improve quality and increase work productivity within the healthcare sector. As a result, an increase is seen in e-health solutions developments with the aim to improve healthcare services, hospital information systems, health decision support, telemedicine and other technical systems that have the potential to reduce cost, improve quality, and enhance the accessibility and delivery of healthcare. However, unfortunately their implementation contiues to fail. Although there are several reasons for this, in this study a lack of project quality management is viewed as a key contributor to the failure of e-health solutions implementation projects in rural hospitals. This results in neglected aspects of quality assurance (QA), which forms an integral part of project quality management. The purpose of this study is to develop a Genertic Quality Assurance Model (GQAM) for the successful acquisition (i.e. development and implementation) of e-health solutions in rural hospitals in the Eastern Cape Province to enable improved quality of care and service delivery. In order to develop and test this model it was necessary to identify the QA methodologies that are currently used in rural hospitals and to evaluate their strengths and weaknesses, as well as their impact on project success. The study is divided into four phases; in each phase different study designs were followed. The study used triangulation of qualitative and some elements of quantitative research approaches, in terms of which a case study approach was adpoted to answer the research questions. This study did indeed develop a GQAM that can be used to ensure e-health solution success in rural hospitals. Furthermore, to aid in the implementation of this model, a set of QA value chain implementation guidelines were developed, as a framework, to inject the nodel into typical (SDLC) phases.
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- Date Issued: 2010
Grade 9 second-language learners in township schools : issues of language and mathematics when solving word problems
- Authors: Sepeng, Johannes Percy
- Date: 2010
- Subjects: Mathematics -- Language , Mathematics -- Study and teaching , Language and languages -- Mathematics , Second language acquisition -- Study and teaching
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9498 , http://hdl.handle.net/10948/1455 , Mathematics -- Language , Mathematics -- Study and teaching , Language and languages -- Mathematics , Second language acquisition -- Study and teaching
- Description: Second language (English) learning of mathematics is common in South African mathematics classrooms, including those in the Eastern Cape Province of South Africa where isiXhosa speakers are taught in the language that is not spoken at home by both teachers and learners. The purpose of this research was to investigate issues of language, both home (isiXhosa) and the language of learning and teaching (LoLT), i.e. English, when 9th grade second language learners engage in problem-solving and sense-making of wor(l)d problems in multilingual mathematics classrooms. In addition, the aim of the study was to explore whether the introduction of discussion and argumentation techniques in these classrooms can ameliorate these issues. The study used a pre-test – intervention – post-test mixed method design utilising both quantitative and qualitative data. The data collection strategies for the purpose of this study included interviews (learners [n=24] and teachers [n=4]), classroom observations, and tests (experimental [n=107] and comparison [69]) in four experimental and two comparison schools in townships of Port Elizabeth. This study is framed by socio-cultural perspective which proposes that collective and individual processes are directly related and that students‘ unrealistic responses to real world problems reflect the students‘ socio-cultural relationship to school mathematics and their willingness to employ the approaches emphasised in school. Analysis of the data generated from pre- and post-tests, interviews and classroom observation schedule suggest that the interventional strategy significantly improved the experimental learners‘ problem-solving skills and sense-making abilities in both English and isiXhosa (but more significantly in English). The statistical results illustrate that the experimental group performed statistical significantly (p < .0005) better in the English posttest compared to comparison group. The data also suggests that the interventional strategy in this study (discussion and argumentation techniques) positively influenced the participating learners‘ word problem-solving abilities. The experimental group appeared to show a tendency to consider reality marginally better than the comparison group after the intervention. In particular, learners seemed to make realistic considerations better in the isiXhosa translation post-test compared to the English post-test. A large practical significant (d = 0.86) difference between the experimental group and the comparison group was also noted in the isiXhosa translation compared to a moderate practical significance (d = 0.57) noted in the English tests after the intervention. As such, the results of the study suggest that the introduction of discussion and argumentation techniques in the teaching and learning of mathematics word problems had a positive effect on learners‘ ability to consider reality during word problem-solving in both languages. Analysis of learners‘ interviews suggests that, although English is the preferred LoLT, they would prefer dual-use/parallel-use of English and isiXhosa for teaching and learning mathematics. There was also evidence of the benefits of code-switching throughout most of the lessons observed, coupled with instances of peer translation, and/or re-voicing. Overall results in this study illustrate that number skills displayed and mathematical errors made by learners seem to be directly related to language use in the classroom.
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- Date Issued: 2010
Metabolic energy relations in the Eastern Cape Angulate Tortoise (Chersina Anguluta)
- Authors: Setlalekgomo, Mpho Rinah
- Date: 2010
- Subjects: Eastern Cape angulate Tortoise , Oxygen consumption (Physiology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10690 , http://hdl.handle.net/10948/1400 , Eastern Cape angulate Tortoise , Oxygen consumption (Physiology)
- Description: The daily oxygen consumption (VO2) pattern, the effects of varying ambient temperatures, season and mass on the resting oxygen consumption (RVO2) of Chersina angulata of the Eastern Cape were investigated. The RVO2 was measured using flow-through respirometry and specific resting oxygen consumption (sRVO2) calculated. To determine the daily pattern in the VO2 of C. angulata, the tortoises were acclimated in an environmentally controlled room (ECR) to an ambient temperature of 26 ± 1°C and a light regime of 14 hours of light and 10 hours of darkness (14L:10D) for at least a week prior to the RVO2 measurements. The RVO2 was measured at a constant temperature of 26 ± 1°C, and at three different light regimes, namely: 14L:10D, constant darkness (DD) and constant light (LL). There were no significant effects of mass or gender on the sRVO2 of the tortoises used. Rhythms in the sRVO2 were detected under all three light regimes. The amplitudes of the rhythm were largest at 14L:10D, followed by DD and smallest at LL regime. The persistence of the rhythmic pattern under constant conditions suggests the existence of an endogenous circadian rhythm in the sRVO2 for adult C. angulata. To test for the effect of ambient temperature on the sRVO2 of adult C. angulata, the tortoises were acclimated to 22 ± 1°C and a 14L:10D light regime prior to the RVO2 measurements. RVO2 was measured at eight experimental temperatures; 14°C, 18°C, 22°C, 26°C, 30°C, 35°C, 38°C and 40°C. The sRVO2 was not influenced by gender and increased with experimental temperatures, but this did not happen consistently over the whole range of temperatures tested. A plateau, possibly a thermal preferendum zone, was detected within the temperature range of 26 - 38°C. Determination of seasonal effect on the sRVO2 of adult C. angulata was accomplished by acclimating tortoises to standard summer and winter conditions. Seasonal effects were tested in the appropriate seasons. Winter experiments were conducted in winter and summer experiments conducted in summer. The RVO2 was measured at experimental temperature 14°C, 18°C and 22°C. In addition RVO2 of iv winter-acclimated tortoises was also measured at 10°C. The sRVO2 increased significantly with increasing temperature within the temperature range tested. No distinct pattern was observed in the seasonal acclimation of adult C. angulata. The metabolic rate-temperature curves of the summer and the winter-acclimated tortoises cross each other. Season and temperature had no significant effects on the mass-scaling exponent of the sRVO2. The exponent ranged from 0.48 to 0.73 within the temperature range of 22 - 38°C. Below and above this temperature range, the exponent ranged from 1.47 to 1.67. An inverse relationship was observed between sRVO2 and body mass over the temperature range of 22 - 38°C. At 14°C and 18°C, sRVO2 increased with body mass, while at 10°C and at 40°C the slope was 1.01.
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- Date Issued: 2010
Lag length selection for vector error correction models
- Authors: Sharp, Gary David
- Date: 2010
- Subjects: Akaike Information Criterion Mathematical models -- Evaluation Autoregression (Statistics) Error analysis (Mathematics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5568 , http://hdl.handle.net/10962/d1002808
- Description: This thesis investigates the problem of model identification in a Vector Autoregressive framework. The study reviews the existing research, conducts an extensive simulation based analysis of thirteen information theoretic criterion (IC), one of which is a novel derivation. The simulation exercise considers the evaluation of seven alternative error restricted vector autoregressive models with four different lag lengths. Alternative sample sizes and parameterisations are also evaluated and compared to results in the existing literature. The results of the comparative analysis provide strong support for the efficiency based criterion of Akaike and in particular the selection capability of the novel criterion, referred to as a modified corrected Akaike information criterion, demonstrates useful finite sample properties.
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- Date Issued: 2010
Dynamic adaptive cost model for wireless Internet connectivity in African rural communities
- Authors: Sibanda, Khulumani
- Date: 2010
- Subjects: Internet , Community development -- South Africa -- Eastern Cape , Cost effectiveness , Wireless communication systems , Rural development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Computer Science)
- Identifier: vital:11389 , http://hdl.handle.net/10353/380 , Internet , Community development -- South Africa -- Eastern Cape , Cost effectiveness , Wireless communication systems , Rural development -- South Africa -- Eastern Cape
- Description: In today’s dynamic technological landscape, wireless communication networks have become an important part of economic development. The emergence of wireless technologies raises hopes to extend communication to remote areas that have not seen any tangible deployment to date. As developing nations pin their hopes to wireless technologies, cost models for wireless communication networks are becoming vital to support the emerging technologies. However, varying cost changes raise critical challenges to the estimation of both capital expenditure and operational expenditure. The network deployment process has numerous events that may cause adjustments to initially estimated project costs. These adjustments are necessary for a cost management plan and this plan includes monitoring cost performance and ensuring that only appropriate changes are made to the network project. The incidents that may cause cost changes can not be entirely predicted as their distribution tend to change dynamically from time to time. Estimating network deployment costs in such a dynamic environment necessitates cost models that can adapt to random occurrence of cost changes. Widely used cost models are usually performed by experienced personnel whose engineering experience is derived from deploying similar networks. In this approach experienced personnel add a certain percentage to the cost estimate to cater for contingency costs. Certainly such an approach depends on individual opinion, making it subjective and void of mathematical estimating relationships which are of paramount importance in ensuring that estimated deployment costs are sufficient to deal with cost uncertainties. We observe that existing approaches can only explore a limited solution space and hence can lead to cost overruns if implemented in dynamically cost changing environments. This thesis presents a wireless communication network deployment cost model that incorporates uncertainties into the final cost estimate. The model is adaptive to unpredictable cost changes since it allows adjustments of confidence levels when calculating contingency costs. This allows dynamically updating the cost changes without the cost model being reconstructed from scratch. We make use of the Poisson process in modeling the occurrence of incidents that are responsible for causing cost changes during network deployment. We also show that the occurrence of the incidents causing cost change are random and tend to follow the Poisson distribution. Using different levels of confidence we model various cost contingencies and make sensitivity analyses to identify the probability of cost overrun when given different contingencies. The dynamic adaptive cost model can be used either at the strategic level to understand the cost of a particular technique or at the operational level, as a way to show how Poisson process in network deployment can compare with engineering experience and other estimating techniques. We believe that the model is useful for remote areas where deployment costs are volatile and the distribution of incidents causing cost change to original cost estimates are diverse and dynamically changing. Further we expect that our research improves the knowledge base of information about the costs for rural communities to connect to the Internet, consequently providing useful input to future policy debates. This work is further poised to be a utility function to help those planning internet infrastructure deployments in least developed regions.
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- Date Issued: 2010
Challenges in topside ionospheric modelling over South Africa
- Authors: Sibanda, Patrick
- Date: 2010
- Subjects: Ionospheric electron density -- South Africa Neural networks (Computer science) Atmosphere, Upper Ionosphere
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5453 , http://hdl.handle.net/10962/d1005238
- Description: This thesis creates a basic framework and provides the information necessary to create a more accurate description of the topside ionosphere in terms of the altitude variation of the electron density (Ne) over the South African region. The detailed overview of various topside ionospheric modelling techniques, with specific emphasis on their implications for the efforts to model the South African topside, provides a starting point towards achieving the goals. The novelty of the thesis lies in the investigation of the applicabilityof three different techniques to model the South African topside ionosphere: (1) The possibility of using Artificial Neural Network (ANN) techniques for empirical modelling of the topside ionosphere based on the available, however irregularly sampled, topside sounder measurements. The goal of this model was to test the ability of ANN techniques to capture the complex relationships between the various ionospheric variables using irregularly distributed measurements. While this technique is promising, the method did not show significant improvement over the International Reference Ionosphere (IRI) model results when compared with the actual measurements. (2) Application of the diffusive equilibrium theory. Although based on sound physics foundations, the method only operates on a generalised level leading to results that are not necessarily unique. Furthermore, the approach relies on many ionospheric variables as inputs which are derived from other models whose accuracy is not verified. (3) Attempts to complement the standard functional techniques, (Chapman, Epstein, Exponential and Parabolic), with Global Positioning System (GPS) and ionosonde measurements in an effort to provide deeper insights into the actual conditions within the ionosphere. The vertical Ne distribution is reconstructed by linking together the different aspects of the constituent ions and their transition height by considering how they influence the shape of the profile. While this approach has not been tested against actual measurements, results show that the method could be potentially useful for topside ionospheric studies. Due to the limitations of each technique reviewed, this thesis observes that the employment of an approach that incorporates both theoretical onsiderations and empirical aspects has the potential to lead to a more accurate characterisation of the topside ionospheric behaviour, and resulting in improved models in terms of reliability and forecasting ability. The point is made that a topside sounder mission for South Africa would provide the required measured topside ionospheric data and answer the many science questions that this region poses as well as solving a number of the limitations set out in this thesis.
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- Date Issued: 2010
Spatially resolved opto-electric measurements of photovoltaic materials and devices
- Authors: Thantsha, Nicolas Matome
- Date: 2010
- Subjects: Photovoltaic cells , Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10520 , http://hdl.handle.net/10948/1123 , Photovoltaic cells , Photovoltaic power systems , Photovoltaic power generation
- Description: The objective of this study is to characterize and analyse defects in solar cell devices. Materials used to fabricate solar cells are not defects free and therefore, there is a need to investigate defects in cells. To investigate this, a topographical technique was developed and employed which uses a non-destructive methodology to analyse solar cells. A system was built which uses a technique based on a laser beam induced current (LBIC). LBIC technique involves focusing light on to a surface of a solar cell device in order to create a photo-generated current that can be measured in the external circuit for analyses. The advantage of this technique is that it allows parameter extraction. Parameters that can be extracted include short-circuit current, carrier lifetime and also the external and internal quantum efficiency of a solar cell. In this thesis, LBIC measurements in the form of picture maps are used to indicate the distribution of the localized beam induced current within solar cells. Areas with low minority carrier lifetime in solar cells are made visible by LBIC mapping. Surface reflection intensity measurements of cells can also be mapped using the LBIC system developed in this study. The system is also capable of mapping photo-generated current of a cell below and above room temperature. This thesis also presents an assessment procedure capable of assessing the device and performance parameters with reference to I-V measurements. The dark and illuminated I-V characteristics of solar cells were investigated. The illuminated I-V characteristics of solar cells were obtained using a defocused laser beam. Dark I-V measurements were performed by applying voltage across the cell in the dark and measuring a current through it. The device parameters which describe the behaviour of I-V characteristic were extracted from the I-V data using Particle Swarm Optimization (PSO) method based on a one-and two-diode solar cell models. Solar cells of different technologies were analysed, namely, single-crystalline (c-Si) and multicrystalline (mc-Si) silicon, Edge-defined Film-fed Growth Si (EFG-Si) and Cu(In,Ga)(Se,S)2 (CIGSS) thin film based cells. The LBIC results illustrated the effect of surface reflection features and material defects in the solar cell investigated. IQE at a wavelength of 660 nm were measured on these cells and the results in general emphasised the importance of correcting optical losses, i.e. reflection loss, when characterizing different types of defects. The agreement between the IQE measurements and I-V characteristics of a cell showed that the differences in crystal grains influence the performance of a mc-Si cell. The temperature-dependence of I-V characteristics of a CIGSS solar cell was investigated. The results showed that, for this material, the photo response is reduced at elevated temperatures. In addition to LBIC using a laser beam, solar spectral radiation was employed to obtained device performance parameters. The results emphasised the effect of grain boundaries as a recombination centres for photo-generated hole-pairs. Lastly, mesa diode characterizations of solar cells were investigated. Mesa diodes are achieved by etching down a solar cell so that the plateau regions are formed. Mesa diodes expose the p-n junction, and therefore mesa diode analysis provides a better way of determining and revealing the fundamental current conduction mechanism at the junction. Mesa diodes avoid possible edge effects. This study showed that mesa diodes can be used to characterize spatial non-uniformities in solar cells. The results obtained in this study indicate that LBIC is a useful tool for defect characterization in solar cells. Also LBIC complements other characterization techniques such as I-V characterization.
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- Date Issued: 2010
Land use, compensational justice and energy resource extraction in Nigeria: a socio-historical study of petroleum and coal mining communities
- Authors: Umejesi, Ikechukwu
- Date: 2010
- Subjects: Compensation (Law) -- Nigeria , Right of property -- Nigeria , Mines and mineral resources -- Nigeria , Coal mines and mining -- Nigeria
- Language: English
- Type: Thesis , Doctoral , PhD (Sociology)
- Identifier: vital:11950 , http://hdl.handle.net/10353/344 , Compensation (Law) -- Nigeria , Right of property -- Nigeria , Mines and mineral resources -- Nigeria , Coal mines and mining -- Nigeria
- Description: Scholarly and public analyses of state-community conflict in resource-rich communities, especially in Nigeria, often portray the compensational practices of the state and extractive enterprises as unjust and unsustainable. According to this view, at least three issues foreground the “unjustness”, namely: a) Inadequate compensation of land owners when land is expropriated or degraded in the process of natural resource exploration and production; b) inadequate periodic rents paid by extractive firms to land owners; and c) lack of, or inadequate socio-economic infrastructure in the host communities of extractive operations. Most analysts have therefore argued for a revamp of the compensation system and have presented the inadequacy of compensation as the underlying cause of conflict in Nigeria‟s mining communities (see Frynas, 2000b:208; Okoji, 2002:205). This thesis subjects the compensation discourse to a closer examination, especially against the backdrop of underdevelopment, pervasive poverty, environmental damage and continuing corporate-community conflict in Nigeria‟s resource-rich rural communities. The main argument is that, because of some of its underlying neoliberal assumptions, much of the compensation discourse is flawed – which is why the discourse obscures the true character of state-community and corporate-community conflict. This more so, because the discourse relies mainly on post-colonial (that is, post-1960) experiences and contemporary advocacy literature, ignores the interplay between history and contemporary developments in state-community relations, and treats compensation as an independent variable. Drawing on the concept of collective memory, and utilising historical, ethnographic and survey data from two of Nigeria‟s oldest petroleum and coal-mining communities, the thesis examines how the evolution of the Nigerian state and collective memory about aspects of that evolution have shaped state-community relations in the extractive sector. It situates state- iii community resource-related conflict within the wider socio-historical matrix of state and community contestations for ecological and natural resource sovereignty. The key finding of the thesis is that within the context of socio-ecological rights, compensation demands by local communities are textured. In the case of the communities selected for the study, such demands are often made outside, rather than within, local ethnographic ideas of “justness” and “fairness”. Hence, land-related grievances associated with natural resource extraction persist, regardless of whether or not local demands for compensation are “adequately” met by the state and extractive corporations. The thesis enriches and extends our understanding of natural resource conflict by privileging both the sociological and historical contexts of the conflict and raising questions about the dominance the state enjoys over local communities and indigenous ecological spaces.
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- Date Issued: 2010
Justice through language : a critical analysis of the use of foreign African interpreters in South African courtrooms
- Authors: Usadolo, Sam Erevbenagie
- Date: 2010
- Subjects: Translators
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8363 , http://hdl.handle.net/10948/1503 , Translators
- Description: This study represents an analysis of the use of foreign African interpreters in South African courtrooms in the context of the necessity of court interpreting as a vehicle through which accused persons can express themselves in defence of their rights, which may have been violated. As a background to the study, due consideration is given to the history of interpreting, followed by some theoretical perspectives of interpreting, where the differences between translation and interpreting are explained. The discussion of some of the theoretical issues of interpreting also focuses on the notion of equivalence, and the divergent views of scholars regarding this notion, which range from formal equivalence (a source-language oriented approach), through dynamic equivalence (in terms of which translation/interpreting must be in agreement with the form and cultural expectations of the receptor language community) to skopos theory (functional in approach and target text oriented). In discussing the role of the court interpreter, the role boundaries with regard to his/her professional relationship with other participants in the courtroom are highlighted. A related topic, namely that of quality in interpreting, is investigated in relation to quality control by professional associations in different countries, who act as regulatory authorities in this regard. A review of court interpreting in South Africa and selected countries in Africa and the EU, such as Nigeria, Benin, Kenya, Zimbabwe, Namibia, Mozambique and Portugal reveals that efforts to develop court interpreting in some Africa and EU countries are either non-existent or at an incipient stage of development. While South Africa, compared to other countries in Africa, is making progress, she is far behind EU countries such as the UK, France and Spain –all of which possess accreditation systems, professional associations and registers of court interpreters. An analysis of the data collected on foreign African court interpreters shows that, although they work in the same courtrooms as their South African counterparts on a daily basis, they are treated differently in terms of employment procedures, training, remuneration, and such like. The study points out that some factors such as (a) the lack of adequate crosscultural awareness and (b) of a balanced proficiency in their language pair, as well as (c) and the existence of divergent dialects in those languages may pose a challenge to foreign African court interpreters in interpreting cross-border languages and in performing sight translations. The study further reveals that foreign African court interpreters are in serious breach of the professional code of conduct, as exemplified by instances of conflict of interest and partiality in their practices. As regards the management of court interpreters, the findings indicate a general laxity on the side of management, as a result of which there is a lack, inter alia, of an appropriate evaluation or monitoring strategy aimed at detecting such cases of conflict of interest and partiality.
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- Date Issued: 2010
Analysis processes as antecedents for decision-making related to growth strategies of South African Game Ranchers
- Authors: Van Eyk, Marlé
- Date: 2010
- Subjects: Tourism -- Marketing , Game farms -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9356 , http://hdl.handle.net/10948/1546 , Tourism -- Marketing , Game farms -- South Africa
- Description: Game ranching offers an economic alternative to conventional stock farming and is a means of supplementing income derived from agricultural activities. Competition is intensifying as ranchers continuously look for ways to improve and expand their businesses and gain a competitive advantage. Ranchers consequently have to find strategies that can ensure growth. Since a reciprocal relationship and dependency exists between a game ranch and the environment in which it operates, it is essential that ranchers take cognizance of aspects in the marketing environment that can either limit, and hence encumber the choice of growth strategy, or stimulate the growth potential of game ranches. As the objective of marketing is to offer customers superior value, it is pertinent for ranchers to know and understand the needs, requirements and motivations of visitors. Failure to do so will cause visitors to patronise other game ranches, or alternative tourism offerings that meet their expectations. A literature review was conducted to define strategy and assist in identifying growth strategies available to a game ranch. The literature review assisted in categorising elements in the external, internal and customer analysis phases of strategic marketing management. Surveys were conducted by means of self-completion questionnaires which were distributed throughout South Africa. Two sets of questionnaires were distributed - one to respondents with prior experience of a game ranch, and one to respondents with no-prior experience. A qualifying question directed the fieldworker to decide which questionnaire should be completed by the respondent. The surveys were constructed in such a way as to determine to what extent various factors would persuade respondents to visit a ranch or extend their stay. Based on a factor analysis, an eight factor structure emerged which represented the personal values of respondents and their levels of expectation for each of the factors. The eight factors were stimulation, universalism, tradition, security, hedonism, power, socialisation, and self-direction. The study revealed the following. - The majority of respondents with no-prior experience of a game ranch is either unaware of the offerings of game ranches, or perceives them as too expensive. - The sustainable use of natural resources is not only essential for the existence of a game ranch, but is also an important motivator for respondents to either visit a game ranch or extend their stay at a ranch. - Staff play a critical role in the overall experience of visitors and act as an important motivator to either visit/revisit a game ranch or extend their stay at the ranch. - Clean and comfortable overnight facilities are deemed important by all respondents. - Respondents have a strong desire to relax and spend time with family and friends. A decision-making framework from which game ranches can select applicable growth strategies resulted from the study. The decision-making framework comprises a three-phase process; phase 1 is the identification of a game ranch's target market; phase 2 is the use of a simplistic framework to determine a possible growth strategy for a game ranch; phase 3 is the identification of ways to implement the selected strategy. As the game ranch industry makes significant contributions to the economic, social and ecological welfare of South Africa, this study added to the body of knowledge of game ranching in South Africa, particularly with regard to the growth options available to game ranches. Recommendations for consideration of future research included the following. - As the current study investigated hunting and tourism, future research on growth strategies for game ranches could also include other aspects of game ranching such as the sale of live game and game products. - More focused empirical research into external and internal strategic analysis should be considered to supplement the empirical research into customer analysis resulting from the current study. - Finally, additional information obtained on the external and internal strategic analysis process could lead to expanding the decision-making framework developed in this study into a more holistic tool to be used in selecting a growth strategy, or combination of strategies for a game ranch3.
- Full Text:
- Date Issued: 2010
Fostering information security culture through intergrating theory and technology
- Authors: Van Niekerk, Johannes Frederick
- Date: 2010
- Subjects: Information technology -- Security measures , Data protection , Corporate culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9754 , http://hdl.handle.net/10948/1404 , Information technology -- Security measures , Data protection , Corporate culture -- South Africa
- Description: Today information can be seen as a basic commodity that is crucial to the continuous well-being of modern organizations. Many modern organizations will be unable to do business without access to their information resources. It is therefor of vital importance for organizations to ensure that their infor- mation resources are adequately protected against both internal and external threats. This protection of information resources is known as information security and is, to a large extent, dependent on the behavior of humans in the organization. Humans, at various levels in the organization, play vital roles in the pro- cesses that secure organizational information resources. Many of the prob- lems experienced in information security can be directly contributed to the humans involved in the process. Employees, either intentionally or through negligence, often due to a lack of knowledge, can be seen as the greatest threat to information security. Addressing this human factor in information security is the primary focus of this thesis. The majority of current approaches to dealing with the human factors in information security acknowledge the need to foster an information security culture in the organization. However, very few current approaches attempt to adjust the "generic" model(s) used to define organizational culture to be specific to the needs of information security. This thesis firstly proposes, and argues, such an adapted conceptual model which aims to improve the understanding of what an information security culture is. The thesis secondly focuses on the underlying role that information security educational programs play in the fostering of an organizational information security culture. It is argued that many current information security edu- cational programs are not based on sound pedagogical theory. The use of learning taxonomies during the design of information security educational programs is proposed as a possible way to improve the pedagogical rigor of such programs. The thesis also argues in favor of the use of blended and/or e-learning approaches for the delivery of information security educational content. Finally, this thesis provides a detailed overview demonstrating how the various elements contributed by the thesis integrates into existing trans- formative change management processes for the fostering of an organizational information security culture.
- Full Text:
- Date Issued: 2010
Indigenous technology and culture in the technology curriculum : starting the conversation : a case study
- Authors: Vandeleur, Sonja
- Date: 2010
- Subjects: Curriculum evaluation -- South Africa Curriculum planning -- South Africa Education -- Curricula -- South Africa Technology -- Study and teaching -- South Africa Indigenous peoples -- Education -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1573 , http://hdl.handle.net/10962/d1003455
- Description: Since the collapse of apartheid and the first democratic elections of 1994, education in South Africa has undergone fundamental transformation and part of this transformation was the reconstruction of the school curriculum. The new curriculum, known as Curriculum 2005 and developed in 1997, introduced Technology as a new learning area. This study is based on the inclusion of ‘indigenous technology and culture’, a new aspect introduced in a revision of Curriculum 2005. The broad goal of the study was to examine and explore pedagogic practice in relation to the inclusion of ‘indigenous technology and culture’ in the revised National Curriculum Statement for Technology. The study was informed by an examination of literature pertaining to philosophy of technology, indigenous knowledge systems and technology education. The review of the literature highlighted the contested nature of ‘indigenous knowledge systems’. Philosophies on the nature of technological knowledge were reviewed in order to explore the meaning of ‘technology’, and a comparative review of curriculum reform in regard to technology education in various parts of the world was conducted. This study presented an attempt to determine the rationale for the inclusion of ‘indigenous technology and culture’ in the revised National Curriculum Statement for Technology in South Africa and to explore and examine what teachers’ existing practices were in this regard. It also examined a process of participatory co-engagement with a focus group of teachers. This process was an attempt to implement ‘indigenous technology and culture’ of the curriculum in a more meaningful way. A case study approach using an in-depth, interpretive design was used. A questionnaire, document analysis, interviews and focus group discussions were used to conduct the investigation. What emerged from the data analysis was that there was unanimous support for the inclusion of ‘indigenous technology and culture’ in the technology curriculum, but implementation had been problematic. This was partly due to difficulties with the interpretation of this aspect in the curriculum as well as a lack of meaningful teaching and learning for various reasons. The study revealed that teachers face multiple dilemmas in implementing ‘indigenous technology and culture’ as an assessment standard. These dilemmas are pedagogical, political, conceptual, professional and cultural in nature. The intentions of the study were to build a comprehensive understanding of ‘indigenous technology and culture’ and to determine how a focus group of teachers were dealing with this new inclusion. The interpretive study concluded with implications and recommendations for further studies.
- Full Text:
- Date Issued: 2010
Integrated teaching strategies model for improved scientific literacy in second-language learners
- Authors: Villanueva, Mary Grace Flores
- Date: 2010
- Subjects: Science -- Study and teaching (Elementary) -- South Africa , Science -- South Africa -- Methodology , Science -- Curricula
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9514 , http://hdl.handle.net/10948/1107 , Science -- Study and teaching (Elementary) -- South Africa , Science -- South Africa -- Methodology , Science -- Curricula
- Description: The importance of a scientifically literate society is currently acknowledged both internationally and South Africa. The notion of scientific literacy in South Africa has emerged largely due to the government’s recognition of the role that science and technology plays in economic growth, employment creation, social redress and social development. However, in light of South Africa’s learner performance on international and national assessments such as TIMMS (2003) and PIRLS (2006), as well as the problems of teaching and learning in a second language, there appears to be a primary and pressing need to develop learners’ fundamental sense of scientific literacy (Norris & Phillips, 2003). Expanding learners’ ability to read, write and communicate in science may provide the necessary framework for engaging learners in the critical principles and foundations of the scientific endeavour (Hand, Prain, & Yore, 2001). As such, this study focuses on equipping and training grade six and seven science teachers to develop scientifically literate learners via professional development workshops with a strategy that supports reading, writing, talking and conducting (‘doing’) science through scientific investigations. The typology of triangulation and the mixed method research approach was supported by a fully mixed, concurrent, and equal status design (Leech & Onwuegbuzi, 2007). Quantitative data were collected from the baseline and post-intervention testing of learners’ problem solving skills, as well as their literacy skills in English and isiXhosa. Qualitative measures were generated through classroom observations, teacher interviews and learners’ science notebooks. The study was conducted in two different milieus in the Eastern Cape, South Africa. The first setting, in the rural area of Tyumie Valley near the Hogsback Mountains, was comprised of a sample of grade six and seven (multi-grade classrooms) teachers (n=7) and learners (n=168) from five experimental schools and two comparison schools. The second setting, in the urban townships area east of Port Elizabeth, was comprised of a sample of grade six teachers (n=8) and learners (n=675) from six experimental schools and two comparison schools. Mean differences between the experimental and the comparison groups were computed for the Raven’s Standard Progressive Matrices (RSPM) and the literacy tests, and the data generated were treated with an Analysis of Covariance (ANCOVA). The data suggest that the scientific literacy strategy improved the experimental learners’ problem solving skills. Both experimental groups demonstrated greater gains than that of the comparison schools. However, statistically significant improvements were only detected in Port Elizabeth. Improvements in learners’ literacy skills in isiXhosa and English varied according to each milieu. While the teachers initially identified challenges to learners’ reading and writing abilities, the analysis of learners’ science notebooks suggested that they used writings to support their investigations. Some teachers cited difficulties with certain aspects of the model, such as problems with developing an investigable question and argumentation, yet overall, teachers found the strategy useful for developing learners’ language skills, as well for strengthening their pedagogical practices in science. Teachers’ gradual improvements in the use of the model suggest that they were able to use the scientific literacy strategy to support the cognitive and linguistic development of second-language learners.
- Full Text:
- Date Issued: 2010
Isolation and evolution of novel nucleoside phosphorylases
- Authors: Visser, Daniel Finsch
- Date: 2010
- Subjects: AIDS (Disease) -- Treatment -- Africa HIV Infections -- Treatment -- Africa AIDS (Disease) -- Patients -- Africa HIV-Positive persons -- Africa Antiretroviral agents Pyrimidine nucleotides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3972 , http://hdl.handle.net/10962/d1004031
- Description: Approximately 33.4 million people are living with HIV/AIDS. Of those, 97% live in low and middle income countries, with 22.4 million in sub-Saharan Africa. Only 42% of the people who require anti-retrovirals (ARVs) in low to middle income countries are receiving anti-retroviral therapy (ART). There is a need to develop novel and cost effective methods for producing antiretroviral drugs. Stavudine and azidothymidine (AZT) were identified as potential targets because they could both be produced through a common intermediate – 5 methyluridine (5-MU). It has been established that the biocatalytic production of 5-methyluridine is possible through a reaction known as transglycosylation, in a process which has not previously been demonstrated as commercially viable. A selection of biocatalysts were expressed either in recombinant E. coli strains or in the wild type organisms, purified and then screened for their ability to produce 5-MU. A combination of Bacillus halodurans purine nucleoside phosphorylase 1 (BHPNP1) and E. coli uridine phosphorylase (EcUP) gave the highest 5-MU yield (80%). This result represents the first combination of free enzymes from different organisms, giving high yields of 5-MU under high substrate conditions. Both enzymes were purified and successfully characterised. The established pH optimum was pH 7.0 for both enzymes. Temperature optima and stability data for BHPNP1 (70 C and t1/2 at 60 C of 20.8 h) indicated that the biocatalytic step was operating within the capabilities of this enzyme and would operate well at elevated temperatures (up to 60 C). Conversely, the temperature optimum and stability data for EcUP (optimum of 40 C and t1/2 at 60 C of 9.9 h) indicated that the enzyme remained active at 40 C for the duration of a 25 h biotransformation, but at 60 C would only be operating at 20% of its optimum activity and would lose activity rapidly. BHPNP1 and EcUP were used in a bench scale (650 ml) transglycosylation for the production of 5-MU. A 5-MU yield of 79.1% was obtained at this scale with a reactor productivity of 1.37 g.l-1.h-1. Iterative saturation mutagenesis was used to rapidly evolve EcUP for improved thermostability. A moderately high throughput colorimetric method was developed for screening the mutants based on the release of p-nitrophenol upon phosphorolysis of a pyrimidine nucleoside analogue. By screening under 20 000 clones the mutant UPL8 was isolated. The mutant enzyme showed an optimum temperature of 60 C and improved stability at 60 C (t1/2 = 17.3 h). The increase in stability of UPL8 is due to only 2 mutations (Lys235Arg, Gln236Ala). These mutations may have caused an increase in stability due to interactions with other structural units in the protein, stabilization of the entrance to the binding pocket, or by decreasing the flexibility of the α-helix at the N-terminus. Transglycosylation experiments showed that the mutant enzyme UPL8 is a superior catalyst for the production of 5-MU. A 300% increase in reactor productivity was noted when free enzyme preparations of UPL8 was combined with BHPNP1 at 1.5% m.m-1 substrate loading. The high yield of 5-MU (75-80% mol.mol-1) was maintained at 9% m.m-1 substrate loading. A commercially viable productivity of 31 g.l-1.h-1 was thus realised. Further optimisation of the process could produce still higher productivities. Future work in directed evolution of nucleoside phosphorylases is envisaged for improved stability and enhanced substrate range for application to other commercially relevant transglycosylation reactions.
- Full Text:
- Date Issued: 2010
Intertidal patterns and processes : tracking the effects of coastline topography and settlement choice across life stages of the mussels perna perna and mytilus galloprovincialis
- Authors: Von Der Meden, Charles Eric Otto
- Date: 2010
- Subjects: Mexilhao mussel -- Behavior -- South Africa Mytilus galloprovincialis -- Behavior -- South Africa Perna -- Behavior -- South Africa Mussels -- Ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5721 , http://hdl.handle.net/10962/d1005407
- Description: Within landscapes, spatial heterogeneity is common and specific landscape features can influence propagule dispersal by wind or water, affecting population connectivity and dynamics. Coastline topographic features, such as bays and headlands, have a variety of biophysical effects on nearshore oceanography, larval transport, retention and supply, and the processes of larval settlement and recruitment. Although this has been demonstrated in several parts of the world, engendering a perception of a general ‘bay effect’, few studies have investigated this generality in a single experiment or region, by replicating at the level of ‘bay’. The Agulhas biogeographic region of the south coast of South Africa is a useful system within which to test for such generality. Using the intertidal mussels Mytilus galloprovincialis and Perna perna as model organisms, patterns of adult distribution were surveyed across four large ‘halfheart’ bays and intervening stretches of open coast, providing replication at the level of ‘bay’ and duplication of ecologically similar species. In support of a general, pervasive influence of bays on intertidal populations, mussel cover was found to be greater in bays than on the open coast for both species, although the effect was strongest for M. galloprovincialis. To explain this adult distribution, settlement, post-settlement mortality and recruitment were examined over 12mo at the same sites, with the prediction that rates of each would favour larger bay populations. Contrary to this, an interaction between month and bay-status was found, with greater settlement and recruitment on the open coast than in bays reflecting extreme settlement and recruitment events at 3 westerly open coast sites during summer. Re-analysis excluding these outliers, revealed the expected effect, of greater settlement and recruitment in bays. While this indicates the broad generality of the bay effect, it highlights exceptions and the need for replication in time and space when examining landscape effects. Measuring post-settlement mortality required testing small-scale settlement behaviour on established and newly deployed settler collectors. It was found that all settlers preferred collectors with biofilm, but that primary settlers avoided conspecific settlers, while secondary settlers were attracted to them. With discrepancies in settler attraction to new and established collectors accounted for, initial (over 2d) and longer-term (over 7d) post-settlement mortality rates were found to be substantial (ca 60 %) for both species. No topographic effect on p-s mortality was evident. Finally, recruit-settler, adult-recruit and interspecies correlations were examined at regional and local scales. Synergistic (or neutral) effects maintained the initial settlement pattern in recruit and adult populations regionally, but not at local scales; striking interspecies correlations suggested the influence of common regional transport processes. Ultimately, the results emphasize the importance of the direction of effects in different life stages and at different spatial scales, and the possibility that antagonistic effects may mask even strong patterns.
- Full Text:
- Date Issued: 2010
A social realist analysis of collaborative curriculum development processes in an academic department at a South African university
- Authors: Vorster, Jo-Anne
- Date: 2010
- Subjects: Rhodes University -- Curricula Journalism -- Study and teaching -- South Africa -- Grahamstown Curriculum planning -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3339 , http://hdl.handle.net/10962/d1004314
- Description: This study reports on a social-realist analysis of collaborative curriculum development in a journalism and media studies (JMS) department at a South African university. Archer's social-realist meta-theoretical framework is used to theorise about mechanisms that influence collaborative curriculum development within the context of the JMS Department. The thesis examines the cultural, structural and agential conditions that influenced the process of developing a JMS curriculum that aimed to integrate theory and practice. Bernstein's theories of knowledge recontextualisation and disciplinary knowledge structures are used in the analysis. Bernstein argues that knowledge recontextualisation constitutes a site of struggle. This thesis is an examination of the "struggles" for the epistemic-pedagogic device (Maton's elaboration of Bernstein's epistemic device) during the recontextualisation process that aimed to integrate media studies (MS) and media production (MP) in the JMS curriculum. Traditionally academic work has been an individual endeavour. However, given the growing need to work in disciplinary and inter-disciplinary teams, it is imperative to develop knowledge of the mechanisms that influence such practices. This thesis is a contribution to knowledge of collaborative processes at the level of an academic department in a university. It contributes to knowledge of cultural, structural and agential mechanisms that enable or constrain collaborative curriculum development within a particular kind of context. In addition it contributes to knowledge of the nature of leadership that may be necessary to facilitate productive collaborative relationships and practices in such a context. The curriculum development project reported on in this thesis was initiated in 2003; however, data collection for the study was conducted in 2006 when the curriculum for the fourth year (JMS 4) of the Bachelor of Journalism degree was developed. Since the JMS course prepares students to work as journalists or media workers it is necessary for the curriculum and pedagogy to be oriented both towards the academy and towards the media industries. The aim of the JMS degree is to develop students who will be critically reflexive journalists or media workers. As such the course is both theoretical (MS) and practical (MP). One of the findings of this research project is that the integration of MS and MP is a complex project given that the knowledge of the two disciplines is structured differently. MS is concept-dependent and some aspects of it can be applied to journalism and media practice, while MP is practical and thus context-dependent, though underpinned by theory. A further finding is that both the collaborative work and the integration project required different identity shifts from the lecturers in the JMS Department. Some were more able to make the shifts than others. The thesis shows that the knowledge recontextualisation struggles in the curriculum development processes of the Department of JMS centred around, inter alia, the setting of boundaries between the department and the media and journalism industries, between MS and MP and between MS theory and journalism theory. In addition, existing boundaries between MS and MP lecturers had to be traversed. These boundaries were circumscribed by, amongst other things, unequal power relations emanating from the higher status traditionally accorded to theoretical knowledge by universities, the tensions around the nature of journalism education and training and the differential properties and powers of the various lecturers within the department. The existence of a strong regulative discourse was found to be an important unifying mechanism in a tension-ridden context.
- Full Text:
- Date Issued: 2010
An investigation into the feasibility of incorporating didanosine into innovative solid lipid nanocarriers
- Authors: Wa Kasongo, Kasongo
- Date: 2010
- Subjects: Antiretroviral agents HIV infections -- Drug testing Didanosine Nanoparticles Drug delivery systems Nanostructured materials Lipids -- Therapeutic use
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3800 , http://hdl.handle.net/10962/d1003278
- Description: The research undertaken in these studies aimed to investigate the feasibility of developing and manufacturing innovative solid lipid carriers, such as solid lipid nanoparticles (SLN) and/or nanostructured lipid carriers (NLC) using a hot high pressure homogenization method, for didanosine(DDI). In addition, studies using in vitro differential protein adsorption were undertaken to establish whether the SLN and/or NLC have the potential to deliver DDI to the central nervous system (CNS). Prior to initiating pre-formulation, formulation development and optimization studies of DDI-Ioaded SLN and/or NLC, it was necessary to develop and validate an analytical method for the in vitro quantitation and analysis of DDI. An accurate, precise and sensitive RP-HPLC method with UV detection set at 248 nm was developed, optimized and validated for the quantitative in vitro analysis of DDI in formulations. Pre-formulation studies were designed to evaluate the thermal stability of DDI and to select and characterize lipid excipients that may be used for the manufacture of the nanocarriers. It was established that DDI is thermostable at temperatures not exceeding 163°C and therefore a hot high pressure homogenization technique could be used to manufacture DDI-loaded SLN and/or NLC. Lipid screening studies revealed that DDI is poorly soluble in both solid and liquid lipids. A combination of Precirol® ATO 5 and Transcutol® HP was found to have the best solubilizing-potential for DDI of all lipids investigated. The inclusion of Transcutol® HP into Precirol® ATO 5 changed the polymorphic form of the solid lipid from the stable 13-modification to a material that exhibited the co-existence between α- and β-polymorphic forms. The relatively high solubility of DDI in Transcutol® HP compared to Precirol® ATO 5 was an indication that a solid lipid matrix prepared from a binary mixture of Precirol® ATO 5 and Transcutol® HP was likely to have a higher loading capacity and encapsulation efficiency for DDI than a matrix consisting of Precirol® ATO 5 alone. Furthermore, the potential for the solid lipid matrix to exist in the α- and/or β-modifications when Transcutol® HP was added to Precirol® ATO 5 suggested that expulsion of DDI from a solid lipid matrix during prolonged storage periods was likely to be minimal. Therefore it was considered logical to investigate the feasibility of incorporating DDI into NLC and not in SLN. However, due to the limited solubility of DDI in lipids, formulation development of DDI-loaded NLC commenced using small quantities of DDI. Formulation development and optimization studies of DDI-loaded NLC were initially aimed at selecting a surfactant system that was capable of stabilizing NLC in an aqueous environment. Solutol® HS alone or a ternary mixture consisting of Solutol® HS, Tween® 80 and Lutrol® F68 was found to stabilize the nanoparticles in terms of particle size and the polydispersity index. The use of the ternary mixture as the surfactant system was preferred to using Solutol® HS alone as Lutrol® F68 and especially Tween® 80 have been successfully used to target the delivery of API to the brain. Aqueous DDI-free and DDI-Ioaded NLC containing increasing amounts of DDI were manufactured using hot high pressure homogenization at 800 bar for three cycles. The NLC formulations were characterized in terms of particle size, polydispersity index, zeta potential, and polymorphism, degree of crystallinity, encapsulation efficiency (EE), shape and surface morphology. The mean particle size for all formulations was below 250 nm with narrow polydispersity indices, indicating that narrow particle size distribution had been achieved. The d99% values for all formulations tested, were generated using laser diffractometry, and were below 400 nm, with span values ranging from 0.84 - 1.19 also suggesting that a narrow particle size distribution had been achieved. The zeta potential values measured in double distilled water with the conductivity adjusted to 50 μS/cm ranged from -18.4 to -11.4 mV. In addition, all the formulations showed a decrease in the degree of crystallinity as compared to the bulk lipid material and WAXS shows that the formulations existed in a single β-modification form. Furthermore DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. These parameters remained unaffected for most formulations following storage for two months at 25°C. In addition these formulations contained a mixture of spherical and non-spherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations. These studies showed that it was feasible to develop and incorporate small amounts of DDI into NLC. However in order to use these delivery systems for oral administration of DDI to paediatric patients, strategies to improve the amount of DDI that could be loaded into the particles and to achieve high encapsulation efficiencies had to be developed. The limited solubility of DDI in lipid media was identified as a major factor that affected the loading capacity and encapsulation efficiency of DDI in the NLC. Therefore, a novel strategy aimed at increasing the saturation solubility of DDI in the lipid by attempting to increase the dissolution velocity of the drug in the lipid using a particle size reduction approach, was designed and investigated. DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid medium was reduced gradually using hot high pressure homogenization and the product obtained from these studies was used to manufacture DDI-loaded NLC using a cold high pressure homogenization procedure. Although the encapsulation efficiency and drug loading following use of this approach was relatively high, the particles were large and showed a tendency to grow in size leading to the formation of microparticles after storage for two months at 25°C. In addition, the degree of crystallinity of the nanoparticles increased rapidly over the same storage period which led to expulsion of DDI nanoparticles for the NLC, despite the DDI loading in NLC being unaffected. It was clearly evident that this new approach of manufacturing solid lipid nanocarriers could be used as a platform not only for enhancing the loading capacity of DDI in solid lipid nanocarriers but also for other hydrophilic drugs. Differential protein adsorption patterns of DDI-loaded NLC were generated in vitro using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to establish the potential for these systems to deliver DDI to the CNS. NLC formulations containing small amounts of DDI were used as these formulations showed a better stability profile than the formulation with a higher encapsulation efficiency and drug loading capacity. Furthermore, the encapsulation efficiency and drug loading of DDI were considered sufficient for use in 2-D PAGE studies. Data obtained from 2-D PAGE analysis reveal that DDI-loaded NLC preferentially adsorb proteins in vitro that are responsible for specific brain targeting in vivo. More importantly, these studies reveal that in addition to Tween® 80 that has already been shown to have the potential to target CDDS to the brain, Solutol® HS 15 has the potential to achieve a similar objective. Consequently, DDI-loaded NLC have the potential to deliver DDI to the brain and these results may be used as a platform for conducting in vivo studies to establish whether DDI can cross the blood brain barrier and enter the CNS when administered in NLC which may in turn lead to a major breakthrough in the management of HIV/AIDS and Aids Dementia Complex (ADC).
- Full Text:
- Date Issued: 2010
Searching for common ground: developing mathematical reasoning through dialogue
- Authors: Webb, Marie Lynette
- Date: 2010
- Subjects: Mathematics -- Study and teaching -- South Africa , Mathematics teachers -- Training of -- South Africa , English language -- Usage -- South Africa
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9493 , http://hdl.handle.net/10948/1132 , Mathematics -- Study and teaching -- South Africa , Mathematics teachers -- Training of -- South Africa , English language -- Usage -- South Africa
- Description: In the majority of the schools in the Eastern Cape, South Africa, teaching and learning takes place in the second language, English, of both teachers and learners. The purpose of this research was to elicit the perceptions of teachers in multilingual mathematics classes about language issues that they encounter and to ascertain whether they could experientially learn the theory of dialogic teaching through an intervention in order to introduce dialogue in practice in their classes. The effect of the intervention on teacher practices was qualitatively observed and the effect of the teacher practices on learner reasoning competence, numeracy competence and English language competence was quantitatively tested by using validated pre- and post-tests. The study follows a mixed method concurrent triangulation design with both quantitative and qualitative results. Two cohorts of students/teachers studying for qualifications at Nelson Mandela Metropolitan University centres throughout the Eastern Cape expressed their opinions about language challenges and solutions through questionnaires, reflective writing and poetry. A cohort of BEd Honours (Mathematics and Science) students experienced a semester long intervention on the theory and practice of dialogic teaching, particularly exploratory talk, and were tasked to introduce the practice into their multilingual mathematics classes in the form of reported action research. The next phase of the study focussed on the practices of three teachers and their grade seven multilingual mathematics learners who were observed and tested over a period of nine months. The following year the observations and testing were repeated with one teacher and his grade seven learners to ascertain whether the intervention would result in similar findings. iv The results enhance the validity of the Vygotskian claim concerning the relationship between language use, social interaction and reasoning development. In classes where there was evidence of dialogic practices the learners collaborated in groups using code-switching and their main language. Their reasoning, numeracy and English skills test scores improved statistically significantly. Teachers were able to give voice to their deep-felt emotions through poetry. They felt that the devaluing of isiXhosa had resulted in the loss of learners’ main language literacy competencies and consequent loss of cultural capital; however they considered it necessary to develop English competence in the learners, even if it was at the expense of developing mathematical competence. The introduction of exploratory talk in their home languages served the dual purpose of promoting the value of isiXhosa in an academic environment as well as enhancing mathematical reasoning. It appears that when teachers focus on developing language as a tool for reasoning, significant improvements in learners’ problem solving competences occur. When the language used is the main language of both teachers and learners both mathematical understanding and cultural identity are enhanced. The study concludes with a suggestion for a model for future interventions to train teachers to introduce dialogic practices in multilingual mathematics classes.
- Full Text:
- Date Issued: 2010