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Mapping Grahamstown's security governance network : prospects and problems for democratic policing

  • Authors: Brereton, Catherine Margaret
  • Date: 2006
  • Subjects: Democracy -- South Africa , Police -- South Africa , Police administration -- South Africa -- Grahamstown , Police-community relations -- South Africa -- Grahamstown , Crime prevention -- South Africa -- Grahamstown , Police patrol -- South Africa -- Grahamstown , Private security services -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:2851 , http://hdl.handle.net/10962/d1006323 , Democracy -- South Africa , Police -- South Africa , Police administration -- South Africa -- Grahamstown , Police-community relations -- South Africa -- Grahamstown , Crime prevention -- South Africa -- Grahamstown , Police patrol -- South Africa -- Grahamstown , Private security services -- South Africa -- Eastern Cape
  • Description: The security of its citizens is often regarded as the democratic state's primary raison d'etre. However, with increasing crime and perceptions of insecurity among citizens, along with actual and perceived state policing inadequacies, citizens around the world have sought to make alternative arrangements for their security. The explosion of private alternatives to state policing has resulted in the need for the replacement of former static definitions of policing by more fluid understandings of what policing entails. Policing is no longer an activity undertaken exclusively by the 'state police.' Policing needs to be understood within a framework which recognises the existence of a variety of state, commercial, community groups and individuals which exist within loose and sometimes informal, sometimes formal, networks to provide for the security of citizens. Preceding the country's transition to democracy in 1994 'state' policing in South Africa was aimed at monitoring and suppressing the black population and as a result it conducted itself in a largely militaristic way. When the government of national unity assumed power in 1994 it was indisputable that the South African Police had to undergo major reform if it was to play an effective, co-operative and accountable role in a democratic South Africa. While state policing has unquestionably undergone enormous changes since the advent of democracy in 1994, so too has non-state policing. It is widely accepted that the dividing line between state and non-state policing in South Africa is increasingly blurred. Policing, by its very nature, holds the potential to threaten democracy. Consequently it is important that policing is democratically controlled. According to the Law Commission of Canada four values and principles - justice, equality, accountability, and efficiency - should support policing in a democracy. This thesis is a case study of policing in Grahamstown, a small city in South Africa's Eastern Cape province. It will be shown that the policing problem that currently plagues Grahamstown, and by extension South Africa, is not simply the result of a shortage of providers but rather a problem of co-coordinating and monitoring security governance to ensure that the city does not further develop into a society where the wealthy have greater access to security than the poor.
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  • Date Issued: 2006

Master of Education research portfolio

  • Authors: Iitula, Helena
  • Date: 2006
  • Subjects: Education -- Namibia Curriculum planning -- Namibia Education and state -- Namibia Competency-based education -- Namibia Teachers -- Training of -- Namibia Education, Secondary -- Namibia
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1948 , http://hdl.handle.net/10962/d1008196
  • Description: This Portfolio was submitted in 2005 to Rhodes University as a Research Portfolio presented in partial fulfilment of the requirements for the degree of Master of Education in General Education Theory and Practice. The Portfolio consists of seven (7) key parts. The reader of this Portfolio is courteously informed that the structure of this portfolio is to some extent differ from the thesis structure. Thus, the reader should be attentive not to weigh against the two. Further more, I hereby declare that this portfolio is my own work and that all the sources that I have used or quoted have been indicated and acknowledged by means of references indicated at the end of each part. Part 2 and 6 are the core parts of the portfolio. The focal point of part 2 is the contextual curriculum analysis of Grade 8-10 Oshindonga Curriculum in order to investigate its implementation in four educational circuits: Oshigambo, Onathinge, Onyaanya and Omuthiya in Oshikoto Region. Based on the findings of this analysis, lack of critical inquiry and reflective practice among Oshindonga teachers was identified as one of the major obstacles that preventing the effective implementation of the curriculum. Most of these teachers are Basic Education Teacher Diploma (BETD) postgraduates. Thus, part 3 and 4 were developed as supplements to inform the main research paper (part 6) which is related to teacher's professionalism in the classroom. The focus of part 3 (literature review) was on the teacher as a reflective practitioner. This is in line with the Namibian Education Policy, which identifies reflective practice as the heart of teacher professionalism. In this part, I explored a variety of views related to the notion of professionalism in teaching. I have also focused on views related to teacher's professional development both on macro and micro levels. These views provided a clarification and an underpinning framework on which to base my analysis of reflective practice as professionalism in education. Part 4 (education theories) focused on the digging of understanding of knowledge as an important theoretical domain of behaviourist and constructivist theories. I have tried to establish how the two theories (Behaviourist and Constructivist) view knowledge and its acquisition and to gain an understanding of how the two theories have been informing the practice. Subsequently, part 6 meant to investigate and assess the extent to which Basic Education Teacher Diploma postgraduate teachers are autonomously applying the theory of critical inquiry and reflective practice in the classroom. Both part 2 and 6 have findings. There is much correlation between the issues and problems in the implementation of the curriculum as identified in part 2 and the findings of the main research paper (part 6). Though critical inquiry and reflective practice is the key journey towards a high level of reflectivity and one of the significant characters of teacher professionalism in the classroom, most issues and problems identified were related to the insufficient practice of critical inquiry and reflective practices. Low correlation was found between critical inquiry and reflective practice theory and teachers' practices in the classroom. Despite to the fact that various rationales were mentioned as to why critical inquiry and reflective practice successful implementation is not taking place, the study positioned an emphasis on team working at school, cluster and circuit base that could contributed to a great extend to making teachers more competent and supporting themselves in mastering the applicable critical inquiry and reflective practice skills.
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  • Date Issued: 2006

Metabolic effects brought about by tricyclic antidepressants and the contribution of a medicinal plant in alleviating high fat diet induced insulin resistance in male wistar rats

  • Authors: Chadwick, Wayne
  • Date: 2006
  • Subjects: Rats -- Metabolism , Diabetes -- Research , Medicinal plants -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10329 , http://hdl.handle.net/10948/461 , Rats -- Metabolism , Diabetes -- Research , Medicinal plants -- South Africa
  • Description: Type II diabetes is becoming a growing problem in developed countries worldwide. The median age for diagnosis was around sixty, but recent surveys have shown that the entire age distribution curve shifting left. The incidence of type II diabetes is thought to be parallel with the growing rate of obesity associated with an unhealthy western diet. Type II diabetes is an expensive disease to manage, it is for this reason that cheaper medication needs to be investigated in the form of traditional plants, such as Sutherlandia frutescens. Prescription medication, such as tricyclic antidepressants, may also increase body weight thereby playing a role in obesity. The cause of weight gain in such cases may go unrecognized or lead to cessation of the medication with or without the practitioner’s knowledge or approval. It is therefore necessary to investigate the causative agents responsible for the excessive weight gain. Drinking water containing extracts of S. frutescens or metformin was administered to two groups of eleven insulin resistant male Wistar rats. The insulin resistant control group received water without any medication. Rats were sacrificed after 8 weeks allowing for fasting blood glucose, insulin and tissue glycogen content determination. Glucose uptake was also determined using [3H] deoxyglucose. The effect of the medication and the diet on muscle post receptor insulin signaling proteins was determined through Western blots. Liver proteomics was also performed using 2-D electrophoresis. In a separate experiment 26 male Wistar rats were exposed to strepotozotocin toxin, 7 of these rats received intravenous insulin treatment, 7 rats received S. frutescens extract and 7 rats received a combination of both medications, the remaining 5 received no treatment and served as the control. Rats were sacrificed after 6 days allowing for fasting blood glucose, insulin and tissue glycogen content determination. Two groups of 14 male Wistar rats received amitriptyline or trimipramine (common tricyclic antidepressants) in their drinking water, the control group (30 rats) received water without any medication. The rats’ weight and food consumption was monitored throughout the trial and their oxygen consumption was also determined. Rats were sacrificed after 6 weeks or 14 weeks of medicinal compliance allowing for fasting blood glucose, insulin and tissue glycogen content determination. Glucose uptake was also determined using [3H] deoxyglucose. S. frutescens treatment normalized circulating serum insulin levels and significantly increased the rate of glucose clearance. Certain post receptor insulin signaling proteins were also significantly increased relative to the insulin resistant control group. 2-D electrophoresis identified the normalization of protein levels associated with the urea cycle. S. frutescens was also able to, independently; maintain normoglycaemic levels in the strepotozotocin treated group. The tricyclic antidepressants significantly increased blood glucose levels while significantly reducing tissue glycogen levels for both sacrifice periods. Serum insulin remained unchanged while a significant increase in insulin degradation and insulin degrading enzyme levels were found for both antidepressants. S. frutescens shows promise as a low cost antidiabetic medication for future use. Although the antidepressants did not promote weight gain, the increase in blood glucose levels may be cause for concern in patients with a pre-disposition toward developing diabetes.
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  • Date Issued: 2006

Metathesis catalysts : an integrated computational, mechanistic and synthetic study

  • Authors: Sabbagh, Ingrid Theresa
  • Date: 2006
  • Subjects: Metathesis (Chemistry) Catalysis Metal catalysts Chemical kinetics
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4397 , http://hdl.handle.net/10962/d1006208
  • Description: An integrated approach to the design of potential rutheniun-based metathesis catalysts is described, in which closely defined synthetic forays provide the focus and rationale for detailed computational and mechanistic studies. The ground-state geometry of a 1st-generation Grubbs catalyst has been explored at the molecular mechanics, semi-empirical and DFT levels, and the resulting structures have been shown to compare favourably with literature data and with the structure of a known crystalline analogue. The DMol³ DFT code has also been shown to represent accurately both the geometry of the corresponding co-ordinatively unsaturated monophosphine derivative, and the ligand dissociation energy associated with its formation. A DFT free-energy profile of the degenerate metathesis of ethylene has been generated, using a truncated model of the 1st-generation Grubbs catalyst, permitting location, for the first time, of the three expected transition states and providing new information regarding the rate-determining step. DFT methods have been used to facilitate the design of a tridentate camphor-derived ligand for use in the construction of a novel Grubbs-type catalyst. The phosphine ligand dissociation energy of the putative catalyst and the ethylene metathesis energy profile of a truncated model have also been studies at the DFT level. The attempted synthesis of the proposed ligand proceeded via a novel 8-bromocamphoric anhydride intermediate and afforded several unexpected and novel products, including a cisfused γ-Iactone, and a bromo camphoric acid derivative. Single crystal X-ray analysis of the latter reveals a chiral, polymeric H-bonded packing arrangement, rendering it suitable for chiral inclusion studies. Computational methods, including the GAUSSIAN-based GIAO NMR prediction technique, were used to support the structural characterisation of the novel camphor derivatives. DFT-Ievel computational analysis of the C-8- and C-9 bromination of camphor has afforded theoretical insights which permit the reconciliation of two earlier empirical explanations regarding the regioselectivity of these transformations; moreover, the theoretical results suggest that a third, previously disregarded factor, plays a significant role. A coset analysis, in conjunction with DFT-Ievel energy profiling, has also been used to resolve conflicting opinions regarding the origin of the major byproduct. Computed electronic parameters (CEP's) have been calculated for the anionic ligands involved in a series of 2nd-generation Grubbs-Hoveyda-type catalysts, and used to explain some apparently anomalous trends in catalyst activity. A linear relationship between ligand CEP's and selected ¹H NMR chemical shifts has also been demonstrated and used to identify a transient ruthenium complex in solution. The ability of the malonate di-anion to bind to ruthenium in a bidentate manner has been explored and demonstrated, under suitable conditions. DFT methods have been used to design and assess the ruthenium-chelating potential of a novel tridentate malonate derivative. A synthetic pathway to this ligand has been designed and several novel heterocyclic intermediates have been isolated and characterised. An NMR-based kinetic study of the Grubbs-catalysed self-metathesis of l-octene has been completed, and the effects of temperature, concentration and solvent variations on the kinetic parameters have been studied. Application of the Guggenheim method and a simplified mechanistic model has permitted the accurate calculation of pseudorate constants for the initiation and, for the first time, the propagation phase of the reaction. Theoretical studies of this reaction at the DFT and molecular mechanics levels have been shown to support previous assumptions regarding the selectivity and temperature-dependence of metallacycle formation.
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  • Date Issued: 2006

Models of internet connectivity for secondary schools in the Grahamstown circuit

  • Authors: Brandt, Ingrid Gisélle
  • Date: 2006
  • Subjects: Internet in education -- South Africa -- Grahamstown , Computer networks -- South Africa -- Grahamstown , Information technology -- Study and teaching (Secondary) -- South Africa -- Grahamstown , Information technology -- South Africa -- Grahamstown , Computer-assisted instruction -- South Africa -- Grahamstown , Telecommunication in education -- South Africa -- Grahamstown , Education, Secondary -- South Africa -- Grahamstown -- Data processing
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4641 , http://hdl.handle.net/10962/d1006566 , Internet in education -- South Africa -- Grahamstown , Computer networks -- South Africa -- Grahamstown , Information technology -- Study and teaching (Secondary) -- South Africa -- Grahamstown , Information technology -- South Africa -- Grahamstown , Computer-assisted instruction -- South Africa -- Grahamstown , Telecommunication in education -- South Africa -- Grahamstown , Education, Secondary -- South Africa -- Grahamstown -- Data processing
  • Description: Information and Communication Technologies (ICTs) are becoming more pervasive in South African schools and are increasingly considered valuable tools in education, promoting the development of higher cognitive processes and allowing teachers and learners access to a plethora of information. This study investigates models of Internet connectivity for secondary schools in the Grahamstown Circuit. The various networking technologies currently available to South African schools, or likely to become available to South African schools in the future, are described along with the telecommunications legislation which governs their use in South Africa. Furthermore, current ICT in education projects taking place in South Africa are described together with current ICT in education policy in South Africa. This information forms the backdrop of a detailed schools survey that was conducted at all the 13 secondary schools in the Grahamstown Circuit and enriched with experimental work in the provision of metropolitan network links to selected schools, mostly via Wi-Fi. The result of the investigation is the proposal of a Grahamstown Circuit Metropolitan Education Network.
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  • Date Issued: 2006

Monetary policy transmission in South Africa: the prime rate-demand for credit phase

  • Authors: Lehobo, Limakatso
  • Date: 2006
  • Subjects: South African Reserve Bank , Monetary policy -- South Africa , Banks and banking -- South Africa , Bank loans -- South Africa , Financial institutions -- South Africa , Finance -- South Africa
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: vital:1128 , http://hdl.handle.net/10962/d1020850
  • Description: A voluminous literature attempts to explain the various channels of the monetary policy transmission mechanism through which central banks ultimately achieve price stability. However, most research focuses on interest rate pass-through and the demand for money phase, while there is limited research on the demand for credit. This study endeavours to contribute to the understanding of this neglected phase of monetary policy transmission by exploring the response of the real demand for bank credit by the private sector to changes in the real prime rate from 1990:1 to 2004:4 in South Africa. Firstly, the behaviour of the real prime rate in relation to the repo rate is explored using graphical analysis. The study observes that an increase in the repo rate causes an increase in the real prime rate, such that there is always a margin of three or four percentage points between the two rates. Secondly, using secondary data, the Johansen methodology is used to determine the relationship between the demand for bank credit and its determinants (GDP, inflation, real prime rate and real yield on government bonds). Two co-integrating relationships are found. The Gaussian errors from one co-integrating vector are used to model the Vector Error Correction Model, which provides the short-run dynamics and the long-run results, through the use of Eviews 5 software. The results of the study show that while all other variables are negatively related to the demand for bank credit in the long-run, GDP has a positive influence. In the short-run, yield on government bonds and inflation coefficients depict a positive association, while the coefficients of real prime rate and GDP are negative. The error correction coefficient is -0.32, which implies that a 32% adjustment to equilibrium happens in the demand for bank credit in a quarter and that the complete adjustment takes about three quarters to complete. Thirdly, the generalised impulse responses results indicate that the impact on the real prime rate affects the demand for bank credit from the first quarter. The study concludes that the real prime rate has a negative impact on the demand for credit both in the short-run and long-run.
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  • Date Issued: 2006

Monitoring and intelligent control for complex curvature friction stir welding

  • Authors: Hua, Tao
  • Date: 2006
  • Subjects: Friction welding , Fuzzy systems
  • Language: English
  • Type: Thesis , Doctoral , DTech
  • Identifier: vital:9612 , http://hdl.handle.net/10948/420 , Friction welding , Fuzzy systems
  • Description: A multi-input multi-output system to implement on-line process monitoring and intelligent control of complex curvature friction stir welding was proposed. An extra rotation axis was added to the existing three translation axes to perform friction stir welding of complex curvature other than straight welding line. A clamping system was designed for locating and holding the workpieces to bear the large force involved in the process between the welding tool and workpieces. Process parameters (feed rate, spindle speed, tilt angle and plunge depth), and process conditions (parent material and curvature), were used as factors for the orthogonal array experiments to collect sensor data of force, torque and tool temperature using multiple sensors and telemetry system. Using statistic analysis of the experimental data, sensitive signal features were selected to train the feed-forward neural networks, which were used for mapping the relationships between process parameters, process conditions and sensor data. A fuzzy controller with initial input/output membership functions and fuzzy rules generated on-line from the trained neural network was applied to perceive process condition changes and make adjustment of process parameters to maintain tool/workpiece contact and energy input. Input/output scaling factors of the fuzzy controller were tuned on-line to improve output response to the amount and trend of control variable deviation from the reference value. Simulation results showed that the presented neuro-fuzzy control scheme has adaptability to process conditions such as parent material and curvature changes, and that the control variables were well regulated. The presented neuro-fuzzy control scheme can be also expected to be applied in other multi-input multi-output machining processes.
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  • Date Issued: 2006

Movement patterns of spotted grunter, Pomadasys commersonnii (Haemulidae), in a highly turbid South African estuary

  • Authors: Childs, Amber-Robyn
  • Date: 2006
  • Subjects: Grunts (Fishes) -- South Africa -- Great Fish River , Pomadasys -- South Africa -- Great Fish River , Freshwater fishes -- South Africa -- Great Fish River , Fishes -- Behavior -- South Africa -- Great Fish River , Estuarine fishes -- South Africa -- Great Fish River , Estaurine ecology -- South Africa -- Great Fish River , Marine ecology -- South Africa -- Great Fish River
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5304 , http://hdl.handle.net/10962/d1005149 , Grunts (Fishes) -- South Africa -- Great Fish River , Pomadasys -- South Africa -- Great Fish River , Freshwater fishes -- South Africa -- Great Fish River , Fishes -- Behavior -- South Africa -- Great Fish River , Estuarine fishes -- South Africa -- Great Fish River , Estaurine ecology -- South Africa -- Great Fish River , Marine ecology -- South Africa -- Great Fish River
  • Description: The principal objective of this thesis was to gain an understanding of the movement patterns of spotted grunter Pomadasys commersonnii, an estuarine-dependent fishery species, in the turbid, freshwater dominated Great Fish Estuary. Both manual and automated telemetry methods were used to monitor the movements of spotted grunter during two separate studies conducted in summer and spring 2003 and 2004. Acoustic transmitters were surgically implanted into twenty spotted grunter with lengths between 263 and 387 mm TL in the first study and twenty spotted grunter ranging between 362 and 698 mm TL in the second study. The specific objectives were to gain an understanding of (i) the time spent in the estuarine environment (ii) the space use and home range size, and (iii) the abiotic factors governing the movement patterns of spotted grunter in the estuary. The nursery function of estuarine environments was highlighted in this study as adolescent spotted grunter spent a significantly larger proportion of their time in the estuary than adult fish (p < 0.0001; R² = 0.62). The increased frequency of sea trips, with the onset of sexual maturity, provided testimony of the end of the estuarinedependent phase of their life-cycle. Although considered to be predominantly marine, the adult spotted grunter in the Great Fish Estuary utilised the estuary for considerable periods. Adults are thought to frequent estuaries to forage, seek shelter and to possibly rid themselves of parasites. During this study, the number of sea trips made by tagged fish ranged from 0 to 53, and the duration ranged from 6 hours to 28 days. The tidal phase and time of day had a significant effect (p < 0.05) on the sea trips undertaken by fish. Most tagged spotted grunter left the estuary during the night (84%) on the outgoing tide, and most returned in the evening (77%) during the incoming tide. Sea temperature (p < 0.0001; R² = 0.34), barometric pressure (p = 0.004; R² = 0.19) and wind (p = 0.01) had a significant effect on the number of spotted grunter recorded in the estuary. Spotted grunter were more prone to return to the estuary after high barometric pressure, when low sea temperatures (upwelling events) prevailed. There was a significant positive relationship between home range size and fish length (p = 0.004; R² = 0.20). Small spotted grunter (< 450 mm TL) appeared to be highly resident, with a small home range (mean size = 129 167 m²), that was generally confined to a single core area. Larger individuals (> 450 mm TL) occupied larger home ranges (mean size = 218 435 m²) with numerous core areas. The home ranges of small and large spotted grunter overlapped considerably yielding evidence of two high use areas, situated 1.2 km and 7 km from the mouth of the Great Fish Estuary. Tagged spotted grunter were located in a wide range of salinity, turbidity and temperature, but were found to avoid temperatures below 16 ºC. The daily change in environmental variables (salinity, temperature and turbidity) had a significant effect on the change in fish position in the estuary (p < 0.0001; R² = 0.38). The distribution of tagged spotted grunter, particularly the larger individuals, in the Great Fish Estuary was influenced by the tidal phase (p < 0.05); they moved upriver on the incoming tide and downriver on the outgoing tide. This study provides an understanding of the movement patterns of spotted grunter in the estuary and between the estuarine and marine environments. Consequently, it provides information that will assist in the design of a management plan to promote sustainability of this important fishery species. The techniques used and developed in this study also have direct application for further studies on other important estuarinedependent fishery species.
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  • Date Issued: 2006

Moving from performance appraisal to performance management at Goldmaster

  • Authors: Verhulp, Ian Marc
  • Date: 2006
  • Subjects: Employees -- Rating of -- South Africa -- Cape Town , Performance standards , Personnel management , Jewelers -- South Africa -- Cape Town
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: vital:8750 , http://hdl.handle.net/10948/635 , Employees -- Rating of -- South Africa -- Cape Town , Performance standards , Personnel management , Jewelers -- South Africa -- Cape Town
  • Description: Performance management systems help align individual goals and objectives with those of the organisation. The system engages employees and thereby directs them toward achieving the strategic goals of the organisation. The purpose of this research study was to conduct an investigation at a manufacturing jeweller in the Western Cape to establish whether a performance management system would facilitate the achievement of the organisation’s strategic goals and objectives. Preliminary investigations showed that the organisation was using a performance appraisal process which was not effective in facilitating the organisation’s strategic objectives. Based on the initial investigation, this study was undertaken. To achieve the goals of this study, 33 employees of the organisation were presented with a questionnaire based on important key elements of performance management. Responses were received from 31 employees, of which one was from senior management, two from management, three from supervisory staff, and 25 from general staff members. Their responses to the questionnaire were analysed and evaluated and, based on the findings, recommendations were made. The results of the study showed that problems exist in the organisation which impede achievement of its strategic goals. A performance management system would assist the organisation in many of these areas to overcome the identified problems. The results of the study will enable the management of the organisation to design and implement a performance management system to facilitate the achievement of the organisation’s strategic goals.
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  • Date Issued: 2006

Non-interactive modeling tools and support environment for procedural geometry generation

  • Authors: Morkel, Chantelle
  • Date: 2006
  • Subjects: Computer graphics -- Mathematical models , Three-dimensional display systems , Computer simulation
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4644 , http://hdl.handle.net/10962/d1006589 , Computer graphics -- Mathematical models , Three-dimensional display systems , Computer simulation
  • Description: This research examines procedural modeling in the eld of computer graphics. Procedural modeling automates the generation of objects by representing models as procedures that provide a description of the process required to create the model. The problem we solve with this research is the creation of a procedural modeling environment that consists of a procedural modeling language and a set of non-interactive modeling tools. A goal of this research is to provide comparisons between 3D manual modeling and procedural modeling, which focus on the modeling strategies, tools and model representations used by each modeling paradigm. A procedural modeling language is presented that has the same facilities and features of existing procedural modeling languages. In addition, features such as caching and a pseudorandom number generator is included, demonstrating the advantages of a procedural modeling paradigm. The non-interactive tools created within the procedural modeling framework are selection, extrusion, subdivision, curve shaping and stitching. In order to demonstrate the usefulness of the procedural modeling framework, human and furniture models are created using this procedural modeling environment. Various techniques are presented to generate these objects, and may be used to create a variety of other models. A detailed discussion of each technique is provided. Six experiments are conducted to test the support of the procedural modeling benets provided by this non- interactive modeling environment. The experiments test, namely parameterisation, re-usability, base-shape independence, model complexity, the generation of reproducible random numbers and caching. We prove that a number of distinct models can be generated from a single procedure through the use parameterisation. Modeling procedures and sub-procedures are re-usable and can be applied to different models. Procedures can be base-shape independent. The level of complexity of a model can be increased by repeatedly applying geometry to the model. The pseudo-random number generator is capable of generating reproducible random numbers. The caching facility reduces the time required to generate a model that uses repetitive geometry.
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  • Date Issued: 2006

Non-renewal of a fixed-term employment contract

  • Authors: Timothy, Lester Clement
  • Date: 2006
  • Subjects: Fixed-term labor contracts -- South Africa , Labor laws and legislation -- South Africa
  • Language: English
  • Type: Thesis , Masters , LLM
  • Identifier: vital:10209 , http://hdl.handle.net/10948/431 , Fixed-term labor contracts -- South Africa , Labor laws and legislation -- South Africa
  • Description: In terms of the common law contract of employment an employee who is a party to a fixed term contract, unlike an indefinite period contract, cannot be dismissed. The contract terminates upon an agreed or ascertainable date determined by the parties and the conclusion of the contract. Section 186(1)(b) of the Labour Relations Act 1995, however, defines the failure to renew a fixed term contract on the same or similar terms where the employee reasonably expected the contract to be renewed, as a dismissal. In this treatise the scope and content of this provision is considered with reference to relevant case law. The factors and considerations that establish a reasonable expectation are highlighted and considered. The question as to whether or not this provision also provides for the situation where an employee expects indefinite employment is also considered and critically discussed. The author concludes that the provision should not be interpreted in such a manner that an expectation of permanent employment is created.
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  • Date Issued: 2006

Nutrient dynamics in and offshore of two permanently open South African estuaries with contrasting fresh water inflow

  • Authors: Jennings, Michael Evan
  • Date: 2006
  • Subjects: Estuaries -- South Africa -- Great Fish River , Estuaries -- South Africa -- Kariega River , Marine ecology -- South Africa , Freshwater ecology -- South Africa , Rivers -- Environmental aspects , Water quality management -- South Africa , Water -- Analysis
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5735 , http://hdl.handle.net/10962/d1005421 , Estuaries -- South Africa -- Great Fish River , Estuaries -- South Africa -- Kariega River , Marine ecology -- South Africa , Freshwater ecology -- South Africa , Rivers -- Environmental aspects , Water quality management -- South Africa , Water -- Analysis
  • Description: The nutrient dynamics in two contrasting estuaries and in the adjacent nearshore environment along the south-east coast of South Africa was investigated seasonally. Due to an inter-basin transfer of water from the Gariep Dam to the Great Fish River, the Great Fish estuary is a fresh water dominated, terrestrially driven system with an annual fresh water inflow of 250 – 650 x 10⁶ m³ per year. In contrast, the Kariega estuary is a fresh water deprived, marine dominated system with a fresh water inflow estimated at 2.5 – 35 x 10⁶ m³per year. The reduced fresh water inflow into the estuary is attributed to regular impoundments along the Kariega River. Water samples were collected from surface and subsurface layers along the length of the estuaries as well as from a series of transects occupied in the nearshore environment. Samples were analysed for nitrate, nitrite, ammonium, phosphate and silicate. Temperature and salinity were recorded at each station. A Land-Ocean Interactions in the Coastal Zone (LOICZ) budget was constructed for each estuary to describe the role of ecosystem-level metabolism as either a sink or a source of phosphorus, nitrogen and carbon. Seasonal variation in physico-chemical properties and nutrient concentrations in the Kariega estuary was minimal due to constant low inflow, while in the Great Fish estuary, concentrations varied in response to changes in flow rate. Nutrient concentrations were consistently higher in the Great Fish estuary than in the Kariega estuary, largely reflecting differences in fresh water inflow. During periods of high flow (32.92 m³.s⁻¹in the Great Fish River) dissolved inorganic nitrogen (DIN) concentrations in the Great Fish estuary were an order of magnitude higher than those recorded in the Kariega estuary. Results of the LOICZ budgeting procedures revealed that in spite of the contrasting hydrodynamic features, the estuaries behave in largely the same manner – both predominantly sources of nutrients with heterotrophic processes dominating over autotrophic actions and both were net denitrifyers during all surveys. This was, however, due to different sets of processes operating in the two estuaries, namely low nutrient concentrations resulting in microbial activity in the Kariega estuary, and riverine influx of nutrients and phytoplankton combined with a short residence time of the water in the Great Fish estuary. In the marine nearshore environment, higher nutrient concentrations were recorded adjacent to the Great Fish estuary than offshore of the Kariega estuary. This was due to a surface plume of less saline water leaving the Great Fish estuary, which acted as an ‘outweller’ of nutrients. Offshore of the Kariega estuary, on the other hand, the nutrient concentrations were characteristic of marine waters due to a lack of fresh water outflow from the estuary. Nutrient concentrations in the marine environment adjacent to the Kariega estuary were, at times, higher than those recorded within the estuary. This observation supports previous statements which suggest that the Kariega estuary is not an ‘outweller’ of dissolved nutrients and particulate material, but rather an extension of the marine environment.
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  • Date Issued: 2006

On the characterisation of copper indium diselenide based photovoltaic devices

  • Authors: Thantsha, Nicolas Matome
  • Date: 2006
  • Subjects: Photovoltaic cells
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10536 , http://hdl.handle.net/10948/443 , Photovoltaic cells
  • Description: Photovoltaic (PV) modules based on thin film systems of CuInSe2 (CIS) and its alloys on low cost substrates are promising candidates to meet the long term efficiency, reliability and manufacturing cost goals. The attention to the CIS solar cell technology is because of the high absorption coefficient of the solar cell absorber layer. Solar cells and PV modules are conventionally assessed by measuring the currentvoltage characteristic of the device. This thesis presents an assessment procedure developed capable of assessing the device parameters with reference to I-V measurements. This thesis then characterizes the performance of the CIS based solar cells and modules in conjunction with other PV modules of different technologies such as crystalline Silicon modules by analyzing the light and dark I-V measurements of the devices. The light and dark I-V characteristics of PV devices were investigated and device parameters were extracted from the I-V data. The extraction and interpretation of these device parameters has a variety of important applications. It has been proven that the device parameters can be used for quality control during production and to provide insights into the operation of the PV devices, thereby improving the efficiency of the devices. The assessment comprises light I-V measurements at standard test conditions (STC), irradiance dependence measurements, parasitic series and shunt resistances measurements and the dark I-V measurements of the PV devices. The PV modules assessed comprise different technologies, namely, thin film based modules (CIS and a-Si) and multicrystalline Si and Edged-defined Film-fed Growth Si (EFG-Si). The dark I-V measurements results showed that the EFG-Si module has acceptable shunt (900 W) and series (0.4 W) resistances, thereby leading to the higher power output depicted from the light I-V measurements. The low quality cells of a-Si module were so low that the fill factor was the smallest (43%). In addition, the dark I-V measurements results revealed that CIS modules are less dependent to temperature at high voltages.
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  • Date Issued: 2006

Optimisation of an in vitro model for anti-diabetic screening

  • Authors: Wilson, Gayle Pamela
  • Date: 2006
  • Subjects: Hypoglycemic agents , Diabetes -- Treatment -- South Africa , Materia medica, Vegetable -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:10308 , http://hdl.handle.net/10948/428 , Hypoglycemic agents , Diabetes -- Treatment -- South Africa , Materia medica, Vegetable -- South Africa
  • Description: The need for alternative strategies for the prevention and treatment of diabetes is growing rapidly as type II diabetes is reaching epidemic status in our society. This need was the basis for the creation of this study, as it was necessary to start looking towards medicinal plants as potential antidiabetic treatment and no comprehensive in vitro model existed. In creating a model for determining the effects of alternative traditional medicines as antidiabetic potentiates, it was necessary that two metabolic pathways, namely glucose uptake and insulin secretion, which play a significant role in glucose homeostasis, be at the centre of our investigations. The objective of this project was to optimize the methodology required to screen and ultimately determine the effectiveness of the plant extracts Kankerbos and MRC2003, as antidiabetic potentiates, through observing their effects on glucose utilisation and insulin secretion. If these medicinal plants are going to make a positive contribution to the health of type II diabetic South Africans, then the determination of their efficacy is essential. The cell lines used in this study included 3T3-L1 preadipocytes, Chang liver, C2C12 muscle and INS-1 rat pancreatic cells. Each cell line represents a different in vivo organ that is known to have an influence on glucose homeostasis in our bodies, each with its own unique metabolic pathways and mechanisms of activity, thereby making each one a vital component in the study. The positive controls for the two models were insulin and metformin (glucose utilisation) and glibenclamide (insulin secretion). Insulin was shown to provide a significant increase in the amount of glucose taken up in C2C12 muscle and Chang liver cells for acute conditions. Chronic treatments with metformin provided a significant increase in glucose utilised by Chang liver cells. Glibenclamide was an effective positive control for stimulating insulin secretion by INS-1 cells under acute conditions as there was a significant increase in the amount of insulin secreted. MRC2003 did not show any significant antidiabetic activity. Sutherlandia frutescens (Kankerbos) showed biological activities comparable to some of the more recognized antidiabetic compounds throughout the study. With regards to the glucose utilisation model, Kankerbos was seen to have both acute and chronic effects in different cell lines. In the C2C12 muscle cell line, Kankerbos significantly increased glucose uptake when they were exposed to acute conditions. Kankerbos also had a significant effect on the Chang liver cells as it was observed that under both acute and chronic conditions, this plant extract induced the uptake of glucose into these cells. With respect to the insulin secretion model involving INS-1 cells, no significant effect was seen during acute exposure with Kankerbos treatment. However during chronic exposure, an increase in insulin secretion was initiated by this plant extract. Overall, the results of this study suggest that Kankerbos has a twofold mechanism of action for its glucose-lowering effects. Given that Kankerbos is widely available in South Africa, this study was valuable as it provided an indication that Kankerbos has antidiabetic activities and could possibly be used as an alternative antidiabetic medication.
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  • Date Issued: 2006

Overcoming supply line barriers to the implementation of lean manufacturing in the Transwerk Uitenhage Plant

  • Authors: Madwara, Nomonde Juliet
  • Date: 2006
  • Subjects: Production management -- South Africa -- Uitenhage
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: vital:8621 , http://hdl.handle.net/10948/552 , Production management -- South Africa -- Uitenhage
  • Description: The objective of this study is to assess the Lean Manufacturing practices by Transwerk Uitenhage and to reveal the barriers to implementation of lean manufacturing strategies experienced by their supply line. This will be compared to what the literature says and suggestions to overcome these barriers will be developed.
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  • Date Issued: 2006

Participants' experience and perceptions of the Future Search Conference as an organizational change strategy in the Nursing Board of Namibia

  • Authors: Layne, Nelao
  • Date: 2006
  • Subjects: Organizational change -- Namibia Nursing -- Study and teaching -- Namibia
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:1882 , http://hdl.handle.net/10962/d1005909
  • Description: Future Search is a new concept in Namibia. This study looks at the application of a Future Search Conference (FSC) with the Nursing Board of Namibia with a view to investigating participants' experiences and perceptions of the FSC as an organizational change strategy. I conducted a case study in the interpretive paradigm, since I was interested in understanding the subjective experience and individual perceptions of five respondents with regard to the FSC. To obtain in-depth information on how participants felt about the FSC, I employed two data gathering tools: un-structured individual interviews and observation. The findings confirmed that the Future Search is a new concept in the Ministry of Health in particular and in Namibia as a whole. Participants are of the opinion that leaders and managers are key figures in the success or failure of the Future Search. They showed a tremendous interest in the process and are willing to embrace and master the tool so they could try it in their various areas of work. Emphasis was put on the need to get the FSC introduced to leaders and higher management cadres on a wider scale, because they are decision makers and can decide whether or not the Future Search could be institutionalized. This study concludes with an appeal from respondents to be exposed to the Future Search again in a better time frame than the short time we had.
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  • Date Issued: 2006

Patient education : the effect on patient behaviour

  • Authors: Shiri, Clarris
  • Date: 2006
  • Subjects: Patient education -- South Africa -- Eastern Cape Patient compliance -- South Africa -- Eastern Cape Hypertension -- Treatment -- South Africa Health care services -- South Africa Community health services -- South Africa
  • Language: English
  • Type: Thesis , Masters , MPharm
  • Identifier: vital:3790 , http://hdl.handle.net/10962/d1003268
  • Description: Evidence suggests that the prevalence of certain non-communicable diseases, such as hypertension, is increasing rapidly, and that patients with these diseases are making significant demands on the health services of the nations in sub-Saharan Africa. However, these countries also face other health-related challenges such as communicable diseases and underdevelopmentrelated diseases. Developing countries like South Africa have limited resources, in terms of man power and financial capital, to address the challenges that they are facing. Non-communicable diseases cannot be ignored and since health care providers cannot meet the challenges, it is worthwhile to empower patients to be involved in the management of their conditions. Patient education is a tool that can be used to enable patients to manage their chronic conditions and thereby reduce the morbidity and mortality rates of these conditions. The aim of this study was to investigate the effect of a patient education intervention on participants’ levels of knowledge about hypertension and its therapy, beliefs about medicines and adherence to anti-hypertensive therapy. The intervention consisted of talks and discussions with all the participants as one group and as individuals. There was also written information given to the participants. Their levels of knowledge about hypertension and its therapy were measured using one-on-one interviews and self-administered questionnaires. Beliefs about medicines were measured using the Beliefs about Medicines Questionnaire (BMQ) whilst adherence levels were measured using pill counts, elf-reports and prescription refill records. The participants’ blood pressure readings and body mass indices were also recorded throughout the study. The parameters before and after the educational intervention were compared using statistical analyses. The participants’ levels of knowledge about hypertension and its therapy significantly increased whilst their beliefs about medicines were positively modified after the educational intervention. There were also increases, though not statistically significant, in the participants’ levels of adherence to anti-hypertensive therapy. Unexpectedly, the blood pressure readings and body mass indices increased significantly. The participants gave positive feedback regarding the educational intervention and indicated a desire for similar programmes to be run continuously. They also suggested that such programmes be implemented for other common chronic conditions such as asthma and diabetes. This study proved that patient education programmes can be implemented to modify patients’ levels of knowledge about their conditions and the therapy, beliefs about medicines and adherence to therapy. However, such programmes need to be conducted over a long period of time since changes involving behaviour take a long time.
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  • Date Issued: 2006

Pharmaceutical analysis and drug interaction studies : African potato (Hypoxis hemerocallidea)

  • Authors: Purushothaman Nair, Vipin Devi Prasad
  • Date: 2006
  • Subjects: Potatoes -- Africa , Potatoes -- Therapeutic use , AIDS (Disease) -- Treatment , HIV infections -- Drug therapy , Medicinal plants
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:3865 , http://hdl.handle.net/10962/d1015802
  • Description: In order for a medicinal product to produce a consistent and reliable therapeutic response, it is essential that the final composition of the product is invariable and that the active ingredient/s is/are present in appropriate, non-toxic amounts. However, due to the complexity involved in the standardization of natural products, quality control (QC) criteria and procedures for the registration and market approval of such products are conspicuously absent in most countries around the world. African Potato (AP) is of great medical interest and this particular plant has gained tremendous popularity following the endorsement by the South African Minister of Health as a remedy for HIV/ AIDS patients. Very little information has appeared in the literature to describe methods for the quantitative analysis of hypoxoside, an important component in AP. It has also been claimed that sterols and sterolins present in AP are responsible for its medicinal property but is yet to be proven scientifically. To-date, no QC methods have been reported for the simultaneous quantitative analysis of the combination, β- sitosterol (BSS)/ stigmasterol (STG)/ stigmastanol (STN), purported to be present in preparations containing AP. The effect of concomitant administration of AP and other herbal medicines on the safety and efficacy of conventional medicines has not yet been fully determined. Amongst the objectives of this study was to develop and validate quantitative analytical methods that are suitable for the assay and quality control of plant material, extracts and commercial formulations containing AP. Hypoxoside was isolated from AP and characterized for use as a reference standard for the quality control of AP products and a stability-indicating HPLC/ UV assay method for the quantitative determination of hypoxoside was developed. In addition, a quantitative capillary zone electrophoretic (CZE) method was developed to determine hypoxoside, specifically for its advantages over HPLC. A HPLC method was also developed and validated for the quantitative analysis of BSS, STG and STN in commercially available oral dosage forms containing AP material or extracts thereof. The antioxidant activity of an aqueous extract of lyophilized corms of AP along with hypoxoside and rooperol were investigated. In comparison with the AP extracts and also with hypoxoside, rooperol showed significant antioxidant activity. The capacity of AP, (extracts, formulations, hypoxoside and rooperol as well as sterols to inhibit in vitro metabolism of drug substrates by human cytochrome P450 (CYP) enzymes such as CYP 3A4, 3A5 and CYP19 were investigated. Samples were also assessed for their effect on drug transport proteins such as P-glycoprotein (P-gp). Various extracts of AP, AP formulations, stigmasterol and the norlignans, in particular the aglycone rooperol, exhibited inhibitory effects on CYP 3A4, 3A5 and CYP19 mediated metabolism.These results suggest that concurrent therapy with AP and other medicines, in particular antiretroviral drugs, can have important implications for safety and efficacy. Large discrepancies in marker content between AP products were found. Dissolution testing of AP products was investigated as a QC tool and the results also revealed inconsistencies between different AP products.
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  • Date Issued: 2006

Plastochron index - an indicator of plant structure and function a case study using Pisum sativum L

  • Authors: Ade-Ademilua, Omobolanle Elizabeth
  • Date: 2006
  • Subjects: Plant anatomy Plant physiology Peas -- Anatomy Peas -- Physiology
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4183 , http://hdl.handle.net/10962/d1003751
  • Description: The use of chronological age for example, using days after sowing (DAS), or days after germination (DAG) as a time variable may result in the inherent variability between plants resulting in differences which can be large enough to obscure subtle developmental trends that become evident among plants sown at the same time. An alternative to DAS or DAG is the plastochron index (PI), first used by Erickson and Michelini (1957) as a morphological time scale and numerical index; which to according to the authors suggested and represented a more accurate reflection of the developmental status of a plant. The research presented in this thesis was therefore aimed specifically at utilizing the index in qualitative and quantitative analyses, to confirm its usefulness in analyzing and predicting plant growth and development. Specifically this research focused on investigating various morphological and physiological events that together, hopefully, would serve as a template for the prediction of the growth, development and reactions of Pisum sativum L. to different growth conditions. In Chapter 3, the use of the average length of the first pair of leaflets on each node as a suitable parameter for calculating PI in P. sativum is suggested. The results presented in Chapter 3 suggest that plant age is best expressed using the plastochron index, as this reflects the time interval between the initiations of successive pairs of leaflets. This section of the research has been published as “Ade-Ademilua OE, Botha CEJ (2005) A re-evaluation of plastochron index in peas - a case for using leaflet length. South African Journal of Botany 71: 76-80”. The PI formula developed was subsequently used in this research to conduct qualitative and quantitative investigations of plant growth and development in which all data and observations were related directly to the plastochron index. In Chapter 4, the sink to source transition in Pisum sativum L. leaves at different plastochron ages in nodulating plants was investigated using the phloem-mobile fluorescent marker, 5,6-carboxyfluorescein (5,6-CF). The results demonstrated that young leaves remained strong sinks up until LPI 0, after which sink-source transition occurred up to LPI 1.8 and leaflets transitioned to strong source systems by LPI 2.0. A well-developed cross-connected phloem system between paired leaflets in peas, and the petiole and the stem vascular supply was observed. The data presented in the second part of Chapter 4 suggest that the phloem transport between leaflet pairs is independent of the sink/source state of the leaflets, or of movement along the source to sink gradient. The data support the presence of a modular transport system which may ensure re-allocation and balancing between leaflets of the same physiological age and photosynthetic and transport status, thereby load-balancing the local transport system, before exporting to other younger (sink) regions. The investigation of leaf development using the plastochron index (Chapter 5) revealed that the formation of air spaces in the palisade and spongy mesophyll, one of the preparatory events for transition from sink to source state in developing leaves, occurs between LPI 0 and LPI 1 in pea leaflets. Results of the anatomical and ultrastructural study related to PI are presented in Chapter 5. The density of wall ingrowths in transfer cells of minor veins increased with LPI and appeared to be associated with the probable transition to source state and the related potential increase in the production of assimilates for export. The onset of wall ingrowth development in leaflets at LPI 0 provided evidence that sink-to-source transition commences at LPI 0 in P. sativum. Presumably-functional plasmodesmata as well as a few mature sieve elements were evident in class IV veins in the apical region of young and older leaflets at LPI 0. The number of mature sieve elements per vein however, increased with increasing LPI. Most class V veins were still undergoing division at LPI 0 and their sieve elements did not show signs of maturity until LPI 1. The increase in the number of mature metaphloem sieve elements in young, supposedly importing tissue at LPI 0 to older, supposedly exporting tissues at LPI 2 is evidence of the association between phloem maturation and transition from importing to exporting status. In Chapter 6, I report on the effects of elevated CO[subscript 2] on the growth and leaf development of nodulating and non-nodulating Pisum sativum L var. Greenfeast grown under controlled environment of the same nitrogen (6mM) and nitrogen- free nutrient solution conditions. Shortterm exposure to elevated CO[subscript 2] induced rapid plant growth, irrespective of treatment. However, long-term elevated CO[subscript 2] treatment did not affect rate of leaf appearance (RLA) in nodulated plants, irrespective of mineral N supply but enhanced RLA in non- nodulating plants supplied with mineral N. Supplied N resulted in a significant increase in leaflet elongation rate (LfER) under both ambient and elevated CO[subscript 2], but LfER was not significantly affected by nodulation but was increased by high CO[subscript 2]. This suggested that the growth of nodulating P. sativum L may not be significantly affected under CO[subscript 2] levels as high as 1000 μmol mol[superscript -1]. The data suggest that elevated CO[subscript 2] will enhance canopy size, provided adequate soil N is available and more so in non-nodulating plants. This section of the research has been published as “Ade-Ademilua OE, Botha CEJ (2004) The effects of elevated CO[subscript 2] and nitrogen availability supersedes the need for nodulation in peas grown under controlled environmental conditions. South African Journal of Botany 70: 816 – 823”. This thesis demonstrates that the similarity in the qualitative analyses results obtained from plants from different CO[subscript 2], nitrogen and nodulation treatment conditions, highlights the fact that plants of same PI value are at the same developmental state, irrespective of the growth condition. Furthermore, changes in plant structure and function observed under different growth conditions can be related simply to changes in plastochron index. The work presented in this thesis demonstrate that changes in plant structure and function analyzed are related to changes in PI. An important finding of this thesis is that with the use of PI, results can be compiled as a template for predicting the structure- function state of pea plants at any plastochron age, under any growth conditions, before using small representative sample populations.
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  • Date Issued: 2006

Population dynamics of the raggedtooth shark (carcharias taurus) along the east coast of South Africa

  • Authors: Dicken, Matthew Laurence
  • Date: 2006
  • Subjects: Sharks -- South Africa Shark fisheries -- South Africa Fish populations -- South Africa Sand tiger shark Fish tagging -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5310 , http://hdl.handle.net/10962/d1005155
  • Description: This thesis develops the first open population model for any shark species worldwide using the Cormack-Jolly-Seber (CJS) model. In conjunction with a tagging study, five auxiliary studies were conducted to investigate stock structure, post-release mortality, tag shedding, and tag-reporting rates. The results from each of the studies were used to correct for any violations of the models assumptions to provide the first unbiased estimates of survival and abundance for the raggedtooth shark (Carcharias taurus) in South Africa. The C. taurus population exhibited complex stock structuring, by size and sex. Competitive shore anglers fished an estimated 37, 820 fishing days.year⁻¹ (95% C.I. = 28, 281 - 47, 359 days.year⁻¹) for sharks, and caught 1764 (95% C.I. = 321 – 3207) C. taurus. Although released alive, post-release mortality ranged from 3.85% for young-of-the-year sharks to 18.46% for adult sharks. Between 1984 and 2004, a total of 3471 C. taurus were tagged. In all, 302-tagged sharks (8.7%) were recaptured. Both juvenile (< 1.8 m TL) and adult sharks (> 1.8 m TL) displayed philopatric behaviour for specific parts of their ranges, including gestating and parturition areas. Significant differences were observed in the percentage of recaptures between the different tag types, tagging programs, individual taggers and capture methods used to tag sharks. The annual tag retention rate for juvenile sharks, 94.19% (95% C.I. = 80.68% - 100.00%) was significantly higher than for adult sharks, estimated at 29.00% (95% C.I. = 6.76% - 64.39%). Tag reporting rates, from fishermen varied both spatially and temporally from 0.28 (95% C.I. = 0.00 – 0.63) to 0.77 (95% C.I. = 0.56 – 0.97). Associated tag wound damage and biofouling growth indicated that B-type tags were a suitable tag type for use on C. taurus, whereas C-type tags were not. The CJS bias-adjusted estimate for juvenile survival was 0.456 (95% C.I. = 0.367 – 0.516) and for adult sharks, 0.865 (95% C.I. = 0.795 – 0.915). From 1984 to 2004 the mean bias-adjusted population size for juvenile sharks was estimated at 3506 (95% C.I. = 2433 – 4350) and for adult sharks, 5899 (95% C.I. = 7216 – 11904). Trends in abundance over the 20-year study period indicated a stable, healthy population.
  • Full Text:
  • Date Issued: 2006
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