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Mlanjeni's war charms: Ikhubalo likaMlanjeni

- Cocks, Michelle L, Dold, Anthony P

Authors: Cocks, Michelle L , Dold, Anthony P
Date: 2006
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/141349 , vital:37964 , https://hdl.handle.net/10520/EJC112911
Description: Most South Africans are familiar with lucky charms such as the four leaved clover of European origin, the Hamsa Hand (Arabic) or Hamesh Hand (Hebrew), the Hindu lucky elephant representing Ganesha, son of Siva, or the African ikhubalo. Amakhubalo refer to charms, often of plant origin, that have magical powers to ward off danger or to bring good luck. Charm plants are used almost everywhere in the Eastern Cape to ensure health, luck and success in sporting events, business, courtship, legal proceedings, safety against accidents and crime and protection against jealousy and sorcery.
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Date Issued: 2006

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Models of internet connectivity for secondary schools in the Grahamstown circuit

- Brandt, Ingrid Gisélle

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

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Molecular biology studies on the coelacanth: a review

- Modisakeng, Keoagile W, Amemiya, Chris T, Dorrington, Rosemary A, Blatch, Gregory L

Authors: Modisakeng, Keoagile W , Amemiya, Chris T , Dorrington, Rosemary A , Blatch, Gregory L
Date: 2006
Language: English
Type: Article
Identifier: vital:6466 , http://hdl.handle.net/10962/d1005795
Description: The discovery of the African coelacanth in 1938 and subsequently the Indonesian coelacanth in 1998 has resulted in a keen interest in molecular studies on the coelacanth. A major focus has been on the phylogenetic position of the coelacanth. Lobe-finned fish such as the coelacanth are thought to be at the base of the evolutionary branch of fish leading to tetrapods. These studies have further aimed to resolve the phylogenetic relationship of extant lobe-finned fish (two coelacanth species and the lungfishes) to vertebrates. Notwithstanding the lack of readily accessible good-quality coelacanth tissue, several major contributions to coelacanth molecular studies and biology have been possible. The mitochondrial genome sequences of both species of the coelacanth suggest that they diverged from one another 40–30 million years ago. A number of large gene families such as the HOX, protocadherin and heat shock protein clusters have been characterized. Furthermore, the recent successful construction of a large-insert (150–200 kilobase) genomic library of the Indonesian coelacanth will prove to be an invaluable tool in both comparative and functional genomics. Here we summarize and evaluate the current status of molecular research, published and databased, for both the African (Latimeria chalumnae) and the Indonesian (Latimeria menadoensis) coelacanth.
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Date Issued: 2006

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

- Lehobo, Limakatso

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

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Monitoring and intelligent control for complex curvature friction stir welding

- Hua, Tao

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

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

- Childs, Amber-Robyn

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

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Moving from performance appraisal to performance management at Goldmaster

- Verhulp, Ian Marc

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

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Much Ado: Directed by Linda-Louise Swain, 2006. 21 February-4 March: theatre review

- Wright, Laurence

Authors: Wright, Laurence
Date: 2006
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/455654 , vital:75446 , https://hdl.handle.net/10520/EJC48071
Description: Shakespeare’s comedies are full of froth and frivol, none more so than Much Ado, which purportedly advertises an overt lack of seriousness in its title. If a production misses the essential lightness of such plays, two things happen. First, the audience is lost, hopelessly at sea, completely bewildered. Second, those unexpected moments where the genius of comedy suddenly erupts in searing insight become indistinguishable from the general temper of events.
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Date Issued: 2006

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Near-real time foF2 predictions using neural networks

- Oyeyemi, E O, McKinnell, Lee-Anne, Poole, Allon W V

Authors: Oyeyemi, E O , McKinnell, Lee-Anne , Poole, Allon W V
Date: 2006
Language: English
Type: text , Article
Identifier: vital:6804 , http://hdl.handle.net/10962/d1004167
Description: This paper describes the use of the neural network (NN) technique for the development of a near-real time global foF2 (NRTNN) empirical model. The data used are hourly daily values of foF2 from 26 worldwide ionospheric stations (based on availability) during the period 1976–1986 for training the NN and between 1977 and 1989 for verifying the prediction accuracy. The training data set includes all periods of quiet and disturbed geomagnetic conditions. Two categories of input parameters were used as inputs to the NN. The first category consists of geophysical parameters that are temporally or spatially related to the training stations. The second category, which is related to the foF2 itself, consists of three recent past observations of foF2 (i.e. real-time foF2 (F0), 2 h (F−2) and 1 h (F−1) prior to F0) from four control stations (i.e. Boulder (40.0°N, 254.7°E), Grahamstown (33.3°S, 26.5°E), Dourbes (50.1°N, 4.6°E) and Port Stanley (51.7°S, 302.2°E). The performance of the NRTNN was verified under both geomagnetically quiet and disturbed conditions with observed data from a few verification stations. A comparison of the root mean square error (RMSE) differences between measured values and the NRTNN predictions with our earlier standard foF2 NN empirical model is also illustrated. The results reveal that NRTNN will predict foF2 in near-real time with about 1 MHz RMSE difference anywhere on the globe, provided real time data is available at the four control stations. From the results it is also evident that in addition to the geophysical information from any geographical location, recent past observations of foF2 from these control stations could be used as inputs to a NN for near-real time foF2 predictions. Results also reveal that there is a temporal correlation between measured foF2 values at different locations.
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Date Issued: 2006

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Negotiating impoverishment: Farm worker responses to displacement following land invasions in Zimbabwe's "Fast Track Land Reform Programme"

- Hartnack, Andrew Michael Carl

Authors: Hartnack, Andrew Michael Carl
Date: 2006
Subjects: Uncatalogued
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/197076 , vital:45834
Description: This thesis investigates the impacts of sudden, unplanned, and violent displacement on farm workers such as Frank Juwawo during Zimbabwe’s recent Fast Track Land Reform Programme. It seeks to illustrate how the members of a complex community were differentially impacted by displacement and displayed differing abilities to mitigate the resulting social and economic impoverishment. In order to illuminate this particular displacement scenario, this thesis uses theoretical and analytical tools developed in the field of displacement studies, adapting them to suit the kind of displacement experienced by Zimbabwean farm workers. , Thesis (MA) -- Faculty of Humanities, Anthropology, 2006
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Date Issued: 2006

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Nestmate recognition and genetic variability among individuals from nests of the queenless ponerine ant, Streblognathus aethiopicus Smith (Hymenoptera: Formicidae)

- Schluns, E A, Neumann, Peter, Schluns, H, Hepburn, H Randall, Moritz, Robin F A

Authors: Schluns, E A , Neumann, Peter , Schluns, H , Hepburn, H Randall , Moritz, Robin F A
Date: 2006
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/452000 , vital:75094 , https://hdl.handle.net/10520/EJC32667
Description: Nestmate recognition in the queenless ponerine ant, Streblognathus aethiopicus, was evaluated with a behavioural bioassay. Ten pairs of nests were randomly chosen from an aggregation of 74 nests. While nestmates never showed aggression towards each other, the behaviour towards non-nestmates was either aggressive or non-aggressive, demonstrating the ability to recognize nestmates. Also, the nests in this aggregation were evenly spaced, further supporting the notion of territoriality in this species. To evaluate the relative importance of environment and genetics on the observed variation in nestmate recognition, we measured the spatial and genetic distances between nests. Workers of 13 nests were genotyped with the AFLP technique. Multiple regression analysis revealed no significant impact of spatial and genetic distance on aggressive behaviour. Thus, further studies are necessary to reveal the actual mechanisms underlying nestmate recognition in this species. Two distinct groups of nests with genetically homogeneous and heterogeneous workers were found, which may indicate gamergate replacement or colony fission.
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Date Issued: 2006

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New and improved : Linda in Java

- Wells, George C

Authors: Wells, George C
Date: 2006
Language: English
Type: Article
Identifier: vital:6613 , http://hdl.handle.net/10962/d1011511 , http://www.sciencedirect.com/science/article/pii/S0167642305000869
Description: This paper discusses the current resurgence of interest in the Linda coordination language for parallel and distributed programming. Particularly in the Java field, there have been a number of developments over the past few years. These developments are summarised together with the advantages of using Linda for programming concurrent systems. Some problems with the basic Linda approach are also discussed and a novel solution to these is presented. The power and flexibility of the proposed extensions to the Linda programming model are illustrated by considering a number of example applications, including a detailed case study of visual language parsing.
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Date Issued: 2006

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

- Morkel, Chantelle

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

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Non-renewal of a fixed-term employment contract

- Timothy, Lester Clement

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

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Non-steroidal anti-inflammatory agents, tolmetin and sulindac, inhibit liver tryptophan 2,3-dioxygenase activity and alter brain neurotransmitter levels

- Dairam, A, Antunes, Edith M, Saravanan, K S, Daya, Santylal

Authors: Dairam, A , Antunes, Edith M , Saravanan, K S , Daya, Santylal
Date: 2006
Language: English
Type: Article
Identifier: vital:6358 , http://hdl.handle.net/10962/d1006050 , http://dx.doi.org/10.1016/j.lfs.2006.07.028
Description: Hepatic tryptophan 2,3-dioxygenase (TDO) is one of the rate-limiting enzymes in tryptophan catabolism and plays an important role in regulating the physiological flux of tryptophan into relevant metabolic pathways. In this study, we determined the effect of the non-steroidal anti-inflammatory agents, tolmetin and sulindac, on rat liver TDO activity and the subsequent changes in the hippocampal and striatal neurotransmitter levels. The amount of melatonin produced by the pineal gland was also measured using high performance liquid chromatography (HPLC). Treatment of rats with tolmetin or sulindac (5 mg/kg/bd for 5 days) significantly inhibited liver TDO activity. The results show that whilst tolmetin and sulindac increase serotonin levels in the hippocampus, these agents also significantly reduce dopamine levels in the striatum. Tolmetin, but not sulindac, increased the amount of melatonin produced by the pineal gland. The results of this study suggest that whilst tolmetin and sulindac may be beneficial for patients suffering from depression, these agents also have the potential to induce adverse effects in patients suffering with neurological disorders such as Parkinson's disease.
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Date Issued: 2006

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Novel amperometric glucose biosensor based on an ether-linked cobalt(II) phthalocyaninecobalt(II) tetraphenylporphyrin pentamer as a redox mediator

- Ozoemena, Kenneth I, Nyokong, Tebello

Authors: Ozoemena, Kenneth I , Nyokong, Tebello
Date: 2006
Language: English
Type: Article
Identifier: vital:6583 , http://hdl.handle.net/10962/d1004148
Description: The development of cobalt(II) phthalocyanine–cobalt(II) tetra(5-phenoxy-10,15,20-triphenylporphyrin), (CoPc–(CoTPP)[subscript 4]) pentamer as a novel redox mediator for amperometric enzyme electrode sensitive to glucose is described. A glassy carbon electrode (GCE) was first modified with the pentamer, then followed by the immobilization onto the GCE–CoPc–(CoTPP)[subscript 4] with glucose oxidase (GOx) through cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) and Nafion® cation-exchange polymer. The proposed biosensor displayed good amperometric respose charateristics to glucose in pH 7.0 PBS solution; such as low overpotentials (+400 mV versus Ag|AgCl), very fast amperometric response time (~5 s), linear concentration range extended up to 11 mM, with 10 μM detection limit. The biosensor exhibited electrochemical Michaelis–Menten kinetics and showed an average apparent Michaelis–Menten constant (K′M) of 14.91 ± 0.46 mM over a storage period of 2 weeks.
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Date Issued: 2006

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

- Jennings, Michael Evan

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

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Observations of the habitats and biodiversity of the submarine canyons at Sodwana Bay

- Sink, K J, Boshoff, W, Samaai, Toufiek, Timm, P G, Kerwath, S E

Authors: Sink, K J , Boshoff, W , Samaai, Toufiek , Timm, P G , Kerwath, S E
Date: 2006
Language: English
Type: Article
Identifier: vital:6771 , http://hdl.handle.net/10962/d1008065
Description: The discovery of coelacanths, Latimeria chalumnae, in Jesser Canyon off Sodwana Bay in northern KwaZulu-Natal in 2000 triggered renewed interest in the deep subtidal habitats associated with submarine canyons. Information stemming from three recreational Trimix diving expeditions in Wright and Jesser canyons between April 1998 and June 2001 revealed distinct and diverse invertebrate and fish communities in the canyons of the Greater St Lucia Wetland Park (GSLWP). In total, 69 invertebrate taxa were collected from Wright Canyon, including at least 15 new records for South Africa plus 11 potential new species and 16 range or depth extensions. Divers documented the first five coelacanth specimens and obtained information on fish distribution and abundance. Five different habitat types were recognized supporting distinct biological communities; the sandy plains outside of the canyons, scattered rock outcrops within the sandy plains, the canyon margin, canyon walls and caves and overhangs. The canyon margin is the richest habitat and supports dense communities of invertebrate suspension feeders, as well as a diverse and abundant fish fauna. Dominant canyon invertebrates included sponges, black corals, gorgonians, alcyonarian soft corals and stylasterine lace corals. These invertebrates support a diverse epifauna including basket- and brittlestars, winged oysters and other molluscs. The canyons within the GSLWP protect large populations of commercially important linefish species including the sparids, Chrysoblephus puniceus, C. anglicus, Polysteganus praeorbitalis and P. caeruleopunctatus, as well as several species of serranids and lutjanids. Additional biological sampling and standardized quantitative sampling within the canyons and deep reefs is required to develop a better understanding of their biological communities and the factors that shape them.
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Date Issued: 2006

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