Aspects of the new repurchase system of monetary control in South Africa
- Authors: Springfield, Samantha Claire
- Date: 2001
- Subjects: Monetary policy -- South Africa Credit control -- South Africa
- Language: English
- Type: Thesis , Masters , MEcon
- Identifier: vital:940 , http://hdl.handle.net/10962/d1002673
- Description: The main objective of monetary policy is to protect the value of the currency, and in so doing, achieve the objectives of maximum economic growth, development, and the creation of employment opportunities. As from 1985, under the advice of the De Kock Commission, the South African Reserve Bank (SARB), implemented the classical cash reserve system of monetary control. Under this system, the SARB was willing to refinance the money market shortage fully, automatically, and on certain predetermined terms, conditions and costs. However, since the new political dispensation in 1994, South Africa’s financial markets have become more globalized, liberalised, and integrated. Thus, the classical cash reserve system had lost its usefulness, and was no longer effective. As from March 1998, the SARB implemented the new repurchase system of monetary control. In implementing the repurchase system of monetary control, South Africa was adopting a more eclectic approach. This system is aimed at making monetary policy more effective and more flexible in a financial environment filled with complexities. This study finds that the repurchase system has thus far been successful in meeting its objectives. Interest rates are more flexible and sensitive to developments in the domestic and external environment, the signalling mechanism of the SARB has proved to be successful, accommodation and interest rates are closely related and the interbank market has become more developed. Therefore, the repurchase system appears to be more efficient than the previous system of monetary control in South Africa.
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- Date Issued: 2001
Assembly of full-length cDNA, and heterologous expression, of Nudaurelia B virus RNA
- Authors: Luke, Gary Joseph
- Date: 2001
- Subjects: Imbrasia cytherea , RNA , Viruses , DNA
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3913 , http://hdl.handle.net/10962/d1003972 , Imbrasia cytherea , RNA , Viruses , DNA
- Description: Nudaurelia beta virus (NβV) is a monopartite genome virus belonging to the family Tetraviridae. Its host range has been found to be limited to a single insect order, the Lepidoptera (moths and butterflies). The single-stranded positive-sense RNA genome consists of 6625 nucleotides containing two open reading frames (ORFs). The 5' proximal ORF of 5778 nucleotides encodes a protein of 215 kDa containing three functional domains characteristic of RNA-dependent RNA polymerase. The 3' proximal ORF, of 1836 nucleotides, encodes the 66 kDa capsid precursor protein and overlaps the replicase gene by more than 99% and is in the +1 reading frame relative to the replicase reading frame. The full-length cDNA construct of the NβV genome was assembled using a homologous overlapping PCR linking method. The starting material consisted of seven overlapping pieces that were constructed for sequencing. Due to the degradation of the full-length RNA obtained from virus extracted from field-collected Nudaurelia cytherea capensis larvae other alternative methods needed to be applied. Sub-cloning using restriction enzyme sites also required an alternative method being used, due to the abundance of restriction sites of the same type in the NβV genome. This led to the use of a method similar to "DNA Shuffling" where overlapping pieces were connected using a modified PCR protocol. After the construction of the NβV genome, the full-length PCR product was cloned and checked for large insertion and deletions that could have resulted from the PCR amplification. The heterologous expression of the NβV capsid protein linked to a fusion protein (Glutathione S-transferase) in E.coli, confirmed the authenticity of the prescribed capsid gene ORF. The expression showed that the virus protein was subjected to protease digestion in DH5α E.coli, suggesting that the protein was insoluble in the cell cytoplasm. The capsid gene expression in a modified E.coli strain, Epicurian Coli BL21-CodonPlus (DE3)-RIL, resulted in high levels of the correct molecular weight protein with minimal degradation. The modified strain was designed for over-expression of eukaryotic protein with lowered protease activity. The above results have opened the way for further research that would yield valuable insight into the molecular biology and replication strategy of the NβV in cell cultures.
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- Date Issued: 2001
Attitudes and perceptions of marriage and divorce among Indian Muslim students
- Authors: Naidoo, Suraya
- Date: 2001
- Subjects: Muslim families -- Social life and customs , Muslim students -- Attitudes
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3289 , http://hdl.handle.net/10962/d1003077 , Muslim families -- Social life and customs , Muslim students -- Attitudes
- Description: This study explores the question of religion and ethnicity as a source of family diversity and ideology. An ideal-typical "traditional Muslim family ideology" was developed and tested. Eight Indian Muslim students at Rhodes University were asked about their attitudes and perceptions of marriage and family life, to determine the particular type of family ideology that these students embraced. Family-related issues such as marriage; the division of labour; gender roles; the extended family system; divorce; and polygamy were addressed. On the basis of the research results, it was found that these students largely adopted the "traditional Muslim family ideology". Religion and ethnicity were found to play an important role, in the make-up of these students' perception of marriage and family life, and a strong preference for the extended family was shown.
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- Date Issued: 2001
Bandwidth management and monitoring for IP network traffic : an investigation
- Authors: Irwin, Barry Vivian William
- Date: 2001
- Subjects: TCP/IP (Computer network protocol) , Computer networks , Electronic data processing -- Management , Computer networks -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4624 , http://hdl.handle.net/10962/d1006492 , TCP/IP (Computer network protocol) , Computer networks , Electronic data processing -- Management , Computer networks -- Management
- Description: Bandwidth management is a topic which is often discussed, but on which relatively little work has been done with regard to compiling a comprehensive set of techniques and methods for managing traffic on a network. What work has been done has concentrated on higher end networks, rather than the low bandwidth links which are commonly available in South Africa and other areas outside the United States. With more organisations increasingly making use of the Internet on a daily basis, the demand for bandwidth is outstripping the ability of providers to upgrade their infrastructure. This resource is therefore in need of management. In addition, for Internet access to become economically viable for widespread use by schools, NGOs and other academic institutions, the associated costs need to be controlled. Bandwidth management not only impacts on direct cost control, but encompasses the process of engineering a network and network resources in order to ensure the provision of as optimal a service as possible. Included in this is the provision of user education. Software has been developed for the implementation of traffic quotas, dynamic firewalling and visualisation. The research investigates various methods for monitoring and management of IP traffic with particular applicability to low bandwidth links. Several forms of visualisation for the analysis of historical and near-realtime traffic data are also discussed, including the use of three-dimensional landscapes. A number of bandwidth management practices are proposed, and the advantages of their combination, and complementary use are highlighted. By implementing these suggested policies, a holistic approach can be taken to the issue of bandwidth management on Internet links.
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- Date Issued: 2001
Case studies of brain fag syndrome in South Africa
- Authors: Finnemore, Gerard le Cornu
- Date: 2001
- Subjects: Brain fag syndrome , Brain -- Diseases
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2977 , http://hdl.handle.net/10962/d1002486 , Brain fag syndrome , Brain -- Diseases
- Description: Against the background of culture bound syndromes and the universalism/relativism debate, this research set out to investigate the diagnosis of brain fag syndrome by examining case studies in a South African context. Diagnostic criteria were identified by way of an analysis of the symptoms reported by a convenience sample of 20 black students experiencing problems related to study. In-depth case studies were conducted with three of the participants from the sample who most thoroughly met the criteria for brain fag syndrome. In a comparison between the brain fag diagnoses and the DSM-IV diagnoses, it was established that while the DSM-IV was not without merit in a cross cultural context, cultural differences were found which suggested the usefulness of the brain fag syndrome diagnosis. A speculative statement on the universalism/relativism debate was proposed based on the principle of complementarity derived from Quantum physics.
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- Date Issued: 2001
Chemical studies of chromone derivatives
- Authors: Sabbagh, Liezel Veronica
- Date: 2001
- Subjects: Benzopyrans Heterocyclic compounds -- Derivatives Coumarins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4424 , http://hdl.handle.net/10962/d1006899
- Description:
This study has focussed on several aspects of chromone chemistry, viz., (i) the influence of remote substituents on the basicity of 2-(N,N-dimethylamino)chromones, (ii) MoritaBaylis-Hillman reactions of substituted chromone-3-carbaldehydes and (iii) an investigation into the application of chromone chemistry in the total synthesis of the marine natural product, Rietone A. Selected 2-(N,N-dimethylamino )chromones were prepared using two different methods; firstly, via cyclisation of salicylate-derived N,N-dimethyl-3;.(2-hydroxyphenyl)-3- oxopropanamide precursors and, secondly, via 2-hydroxyacetophenone boron difluoride complexes. ¹³C NMR analysis of the 6- and 7-methoxy-2-(N,N-dimethylamino)chromones confirmed that protonation occurs at the chromone carbonyl oxygen rather than the amino nitrogen - a conclusion supported by mol~cular orbital calculations. Potentiometric analysis of 2-(N,N-dimethylamino )chromones in ethanol-water afforded pKa (pK [subscript a]) values in the range 2.22 - 2.52. The observed trend has been rationalised in terms of substituent effects with the aid of molecular orbital calculations at the semi-empirical and ab initio levels, while hydrogen-bonding effects have been used to account for the apparently anomalous result obtained for the 6-nitro derivative. A series of seven substituted chromone-3-carbaldehydes, prepared by the application of Vilsmeier-Haack methodology to the corresponding 2-hydroxyacetophenones, have been examined as substrates for Morita-Baylis-Hillman reactions, using DABCO as the catalyst and three different activated alkenes, viz., methyl acrylate, methyl vinyl ketone and acrylonitrile. In all cases, with the exception of 6-nitrochromone-3-carbaldehyde, the reactions have been shown to afford the expected Morita-Baylis-Hillman products. Use of methyl acrylate and methyl vinyl ketone as the activated alkene has been observed to afford additional, unprecedented dimeric products, which have been unambiguously characterised using a combination of single crystal X-ray analysis and spectroscopic (high resolution MS and NMR) techniques. Different dimer-like adducts have been isolated from reactions in which acrylonitrile was used as the activated alkene, and the structures of these novel products have-been determined
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- Date Issued: 2001
Clustering as a strategy for manufacturing performance in the Eastern Cape Automotive industry
- Authors: Makuwaza, Gwynneth Chandakaita
- Date: 2001
- Subjects: Automobile industry and trade , Automobile industry and trade -- South Africa -- Eastern Cape , Automobile industry and trade -- South Africa -- Eastern Cape -- Performance
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:937 , http://hdl.handle.net/10962/d1002670 , Automobile industry and trade , Automobile industry and trade -- South Africa -- Eastern Cape , Automobile industry and trade -- South Africa -- Eastern Cape -- Performance
- Description: South Africa's current industrial policy focuses on the economy at two levels: a sectoral and spatial level. The former relates to the manner in which industrial policy is concentrating on particular sectors i.e. industrial clusters. This shift in industrial policy from targeting individual industries to an emphasis on industrial clusters, has complemented the change in focus to export promotion under trade policy. Furthermore, there has been increasing recognition of the need to improve industry performance and competitiveness in order to successfully implement export growth. Industry clusters are considered as having the potential to increase manufacturing performance and can provide the basis for sustainable competitive advantage for nations. Consequently the concept of industry clusters was introduced in South Africa in 1997. Because industry clusters are relatively new in South Africa, most of the cluster initiatives in various sectors of the economy are in their early stages of development. Nevertheless, some are already showing signs of potential success in increasing competitiveness in particular sectors. This thesis uses Porter's "diamond" framework apprdach to investigate whether clustering has improved the manufacturing performance of the motor industry in the Eastern Cape. International experience from both developed and developing countries will illustrate the potential of clustering as a powerful strategy in increasing manufacturing performance and consequently competitiveness. Ultimately this should lead to long-term economic development, especially if government adopts clusterbased economic development policies. Information from a survey conducted on both the motor vehicle assemblers and component suppliers is used in this study. The findings reveal that it is mainly the motor vehicle assemblers who have experienced some improvements in manufacturing performance. The components sector on the other hand has not experienced any such improvements. This thesis concludes with the recommendation that it is important to develop cluster policy as a broader and dynamic view of competition. The main emphasis under such policy would be a move from targeting particular industries and providing subsidies towards focusing attention to all clusters in the economy. To effectively apply such a policy requires the repositioning of national, local and provincial government in order to become more involved in regional development issues. Moreover, the various levels of government need to incorporate cluster policy into their competitive strategies.
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- Date Issued: 2001
Cognitive behavioural treatment of chronic fatigue syndrome: an in-depth case study
- Authors: Rusch, Mary L
- Date: 2001
- Subjects: Chronic fatigue syndrome , Chronic fatigue syndrome -- Psychological aspects , Chronic fatigue syndrome -- Exercise therapy , Chronic fatigue syndrome -- Treatment
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3046 , http://hdl.handle.net/10962/d1002555
- Description: Chronic Fatigue Syndrome (CFS) is a chronic disabling condition characterised by persistent physical and mental fatigue, and a variety of somatic, psychological and neurological symptoms. The aetiology of CFS is unknown and the cause of the illness remains controversial. Cognitive-behavioural therapy (CBT) is a non-pharmacological treatment approach that has been shown to be effective in treating patients with CFS. It is based on a model that hypothesises that certain maladaptive thoughts and dysfunctional beliefs may contribute to self-defeating behaviour that perpetuates symptoms and disability, and thereby impedes recovery. The main aim of this study was to critically examine the cognitive-behavioural approach of CFS outlined by Sharpe, Chalder, Palmer & Wessely (1997) by conducting three in-depth case studies. An additional aim was to present a full cognitive developmental case conceptualisation of CFS based on the theories of Leahy (1996) and Young (1994). This case study evaluated the effectiveness of a CBT treatment programme in a 48-year-old Caucasian woman diagnosed with CFS for three years. The treatment consisted of sixteen sessions of CBT and was evaluated both quantitatively and qualitatively. On the basis of this study, a set of core maladaptive schema in the area of disconnection and rejection was identified. In addition, it was found that specific compensatory schemas had developed to offset the core maladaptive schemas and that this compensatory strategy played an important role in maintaining the condition. The results also showed a significant decline in fatigue coupled with a moderate decline in functional disability and depression. A one-month follow-up interview revealed evidence of a substantial consolidation of therapeutic gains in that the improvements observed at the end of the treatment were sustained. Finally, the feasibility of incorporating a cognitive-developmental and/or schema-focused model into the standard CBT treatment model is discussed and the case study method as a research toll is evaluated in light of the findings.
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- Date Issued: 2001
Community knowledge, cohesion and environmental sustainability : an educational case study in Clarkson
- Authors: Uithaler, Eldrid Marlon
- Date: 2001
- Subjects: Community life -- South Africa Social participation -- South Africa Community development -- South Africa Competency-based education -- South Africa Competency-based education -- Curricula
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1453 , http://hdl.handle.net/10962/d1003334
- Description: An ethnographic case study was done in the rural community of Clarkson which lies at the foot of the Tsitsikamma Mountains in the Eastern Cape, South Africa. Rural communities gathered and developed local wisdom on the natural resources around them. The study shows that in the past, life in Clarkson was characterised by such shared wisdom, an abundance of natural resources, as well as strong community cohesion. With the advent of modern lifestyles community cohesion and practices were disrupted and today, people living in Clarkson are less dependent on each other and on local resources. This study suggests that some of the past wisdom, community knowledge, practices and skills that existed for ages in Clarkson, can still be useful today in the context of environmental sustainability. The incorporation of this knowledge into the new outcomes-based education curriculum in South Africa and the local school curriculum, is explored.
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- Date Issued: 2001
Configuring convergence : southern African websites looking at American experience
- Authors: Berger, Guy
- Date: 2001
- Language: English
- Type: text
- Identifier: vital:535 , http://hdl.handle.net/10962/d1008553 , ISBN 0-86810-379-9
- Description: I want the Web to win. Africa’s news sites on the Internet need to succeed and survive. They’re a small guarantee against global marginalisation, and a critical intersection across our continent’s domestic divides. But the outlook is not good. At a conference I went to in Berkeley in April 2001, a venture capitalist had this to say: "If I were to make a speech on when there’ll be investment in new media again, it would be a rather short topic." The alarming closures and retrenchments at news websites in the USA are sending scary signals to our fledgling efforts back here. Starting and growing media enterprises of any sort in African conditions has never been easy. Long starved of investment, our cyberpublishing now faces even greater pressures as old media – newspapers, radio and TV – try to make ends meet under mounting threats. Advertising is shrinking, local costs are rising and currency falls are fuelling the price of imported production factors. Consumers have less cash to spend. Governments are giving even greater problems in some cases. Will we still be here in the morning, and in what condition? This booklet suggests the way forward is for new media to converge with selected partners, old media and new.
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- Date Issued: 2001
Continuity and change in Xhosa historiography during the nineteenth century : an exploration through textual analysis
- Authors: Tisani, Nomathamsanqa Cynthia
- Date: 2001
- Subjects: Xhosa (African people) -- History
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2563 , http://hdl.handle.net/10962/d1002416
- Description: This study is an exploration of the making of Xhosa historiography from the end of the eighteenth century to the close of the nineteenth century. Continuity and change are key features that are identifiable in the writing of Xhosa history over the period. Selected documents provide evidence on how different writers built on the works of their predecessors. At the same time, over a period of hundred years, due to changing socio-political contexts, new ideas and perceptions crept into Xhosa history. European writers, who dominated the writing of Xhosa history, were made up of colonial officials, missionaries, and travellers. Sharing a common European Christian background these writers brought along their particular understanding of history, and held assumptions about the indigenous people and their past. However such assumptions were always in a state of flux. South-east Africans were also major contributors to the making of Xhosa history. Their oral traditions were important sources from which Xhosa history was produced. The African and European encounter in the making of Xhosa history meanHhat historioracy and historiography came together in the production of Xhosa history. At the end of the eighteenth century there were a handful of European travellers who explored the interior of southern Africa and recorded their observations of indigenous communities. These observations of south-east Africans, whom they divided into three racial groups, formed the basis of later writings about the indigenous communiti~s. The beginning of the nineteenth century brought the establishment of British rule at the C,ppe. This introduced new players into the African-European drama that was being acted out on the frontier. Colonial officials set out to inform themselves about the indigenous people, and this meant writing up their history. From the 1820s missionaries were a main source of information on amaXhosa. Xhosa history produced under the missionary influence included works by African converts, among whom Noyi was the most noteworthy. As British imperialism gained ground from the middle of the nineteenth century, history was increasingly used by British officials as a tool to justify their colonial expansion. Under Governor Grey there was a deliberate production of a Xhosa history that depicted amaXhosa as having a barbaric past and in need of civilisation. Theal who consulted Dutch and British archives as well as oral tradition made a major contribution to the writing of Xhosa history. But Theal later began to select evidence to show that amaXhosa were recent immigrants into southeast Africa. During the last quarter ofthe nineteenth century a band of literate Africans, using newspapers like Isigidimi and later Imvo Zabantsundu, embarked on writing African history. This study highlights the development of certain themes in Xhosa history, themes which remained central in later years. The royal theme became pivotal and in the process displaced other histories in African communities, like clan histories. This study has also traced the roots of some historical myths. For example claims by early travellers about an empty land fed into the migration theme which sought to explain amaXhosa as recent immigrants into south-east Africa. Xhosa historiography, just like its European counterpart, marginalised ordinary people, especially women, and became primarily an account of the lives and activities of ruling men.
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- Date Issued: 2001
Credit accessibility and rural development in the former Ciskei: an overview of Keiskammahoek
- Authors: Kimemia, Peter Njau
- Date: 2001
- Subjects: Credit -- Research -- South Africa -- Ciskei , Rural development -- South Africa -- Ciskei , Poor -- South Africa -- Ciskei , Poor -- Developing countries
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3312 , http://hdl.handle.net/10962/d1003100 , Credit -- Research -- South Africa -- Ciskei , Rural development -- South Africa -- Ciskei , Poor -- South Africa -- Ciskei , Poor -- Developing countries
- Description: This study focuses on the issue of credit accessibility for the rural poor. Taking cognisance of the critical role played by innovative micro-lending mechanisms in the sphere of rural development, the study reaffirms the need to enhance access to financial services by rural communities. However, it also reveals the fact that there are numerous impediments to access to credit for the people living in parts of the Keiskammahoek District of the former Ciskei. Key among the impediments has been lack of awareness about the existence and the activities of micro-lending institutions. This has, in a large measure been blamed for many of the rural poor people's failure to approach such institutions for funding. As a result, the affected people's efforts to fully actualize themselves economically have to a certain extent been hampered. Consequently, as its core argument, this study views as crucial the need to tackle all the attendant impediments. It also suggests that as the first step, the government, NGOs as well as formal and informal lending institutions should endeavour to disseminate the requisite information on micro-financing and in enhancing the affected people's institutional capacity to effectively use credit obtained for commercially productive ventures. Without sorting out the basics first, credit extension even when easily availed may not have the desired impact. At worst, it may actually complicate the poverty situation as the people grapple with piling debts.
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- Date Issued: 2001
Cumulative mild head injury in rugby: a comparison of cognitive deficit and postconcussive symptomatology between schoolboy rugby players and non-contact sport controls
- Authors: Beilinsohn, Taryn
- Date: 2001
- Subjects: Rugby football injuries , Head -- Wounds and injuries -- Psychology , Head -- Wounds and injuries -- Complications , Brain damage
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2931 , http://hdl.handle.net/10962/d1002440 , Rugby football injuries , Head -- Wounds and injuries -- Psychology , Head -- Wounds and injuries -- Complications , Brain damage
- Description: This study investigates the cumulative effects of concussive and subconcussive mild head injury on the cognitive functioning of schoolboy rugby players. A comprehensive battery of neuropsychological tests and a self-report postconcussive questionnaire were administered to top level schoolboy rugby players (n=47), and a non-contact sport control group of top level schoolboy hockey players (n=34). Group comparisons of the percentage of individuals with cognitive deficit were carried out between i) the schoolboy rugby and the schoolboy hockey players, ii) the rugby forward and the rugby backline players; iii) the rugby forward and the schoolboy hockey players and, iv) the rugby backline and the schoolboy hockey players. Results on the neuropsychological test battery did not provide any substantial evidence of a higher level of neuropsychological impairment in the rugby players relative to the control group, or in the rugby forward players relative to the rugby backline players. Results obtained on the postconcussive symptom questionnaire provided tentative indications that the rugby players do report a greater frequency of postconcussive symptomatology. The symptoms most frequently reported were being easily angered, memory problems, clumsy speech and sleep difficulties. It was hypothesized that the absence of cognitive impairment in the schoolboy rugby players compared with that noted for professional players was due to their younger age, relatively high IQ and education level and a less intensive level of physical participation in the sport, and hence less accumulated exposure to the game, thereby decreasing their exposure to mild head injuries. From a theoretical perspective, these pre-existing conditions were considered to act as protective factors against reductions in brain reserve capacity and concomitant susceptibility to the onset of neuropsychological dysfunction.
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- Date Issued: 2001
Design, synthesis and characterization of novel rhenium(V) and technetium(V) complexes as potential radiopharmaceuticals
- Authors: Hlabela, Patrick Simon
- Date: 2001
- Subjects: Radiopharmaceuticals , Rhenium , Technetium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4306 , http://hdl.handle.net/10962/d1004964 , Radiopharmaceuticals , Rhenium , Technetium
- Description: A number of bidentate N, N-diethyl-N' -(R ')benzoylthiourea ligands (where R' = H,CH₃,CI,OCH₃ and N0₂) have been synthesized, as well as the three Re(V) precursor complexes, ReOCl₃(PPh₃)₂,[ReO₂(py)₄]CI and [n-Bu₄N] [ReOCI₄J. The reaction of N,N-diethyl-N'-benzoylthiourea (LH) with these three metal precursor complexes in methanol in the presence of a base gave a novel mixed-ligand complex bis(N,N-diethyl-N'-benzoylthioureato)methoxyoxorhenium(V), [ReO(L)₂(OMe)] (1). In the absence of a base and under an inert atmosphere, the reaction between [n-Bu₄N][ReOCI₄] and LH yielded bis(N,N-diethyl-N'-benzoylthioureato)chlorooxorhenium(V), [ReO(L)₂CI] (lb). The reaction of LH with [ReO₂(py)₄]CI in ethanol and iso-propanol in the presence of sodium acetate gave the novel mixed ligand complexes bis(N,N-diethyl-N'benzoylthioureato) ethoxyoxorhenium(V), [ReO(L)₂(OEt)] (6) and bis(N,N-diethyl-N'benzoylthioureato)(iso-propoxy)oxorhenium(V), [ReO(L)₂(OiPr)] (7), respectively. An oxygen bridged dirhenium complex, [(L)₂0Re-O-ReO(L)₂] (15) was obtained when the reaction was carried out in acetonitrile. A series of mixed ligand Re(V)-oxo complexes using N, N-diethyl-Nʾ-(R' )benzoylthiourea (LR'),N,N-morpholino-N' -(R')benzoylthiourea (morph-LR') and 8-(N-(R')benzoylthiocarbamoyl)-1,4-dioxa-8-azaspiro[4.5]decane ligands (spiro-LR') (where R' = H,CH₃,CI, OCH₃ and N0₂) ((1)(14) have been prepared by the reaction of [ReO₂(py)₄]CI and the ligand in the presence of sodium acetate in methanol. The solution state chemistry of these complexes has shown that complexes(1)-(14) (with the exception of (1b)) undergo dimerization in solution to give complex (15) in the presence of water. Preliminary ¹H NMR kinetics studies of the dimerization of (1), (6) and (7) to (15) have shown that the rate of dimerization decreases in the order (7) > (6) > (1). The rate of dimerization has also been compared for complexes (1), [ReO(morph-L)₂(OMe)] (8) and [ReO(spiro-L)₂(OMe)] (13) and the rate of dimerization was found to be fastest for (13). The crystal structures of (1), [ReO(LN0₂)₂(OMe)] (4), (6) and (15) have been determined. The Re(V)-oxo complexes (1), (4) and (6) have a slightly distorted octahedral geometry with the two acylthiourea ligands binding in a cis arrangement in the equatorial plane of the octahedron. The alkoxy and oxo ligands occupy the axial positions and are situated trans to each other. The crystal and molecular structure of complex (15), consist of two slightly distorted octahedral [ReO(L)₂] moieties bridged by an oxygen atom with a Re-O-Re bond angle of 175.2(2)°. The preliminary studies done in the present study have indicated that the complexation chemistry of technetium(V) with the N,N-diethyl-benzoylthiourea is different to that of rhenium (V). The reaction between [n-BuN₄][TcOCl₄] and N,N-diethyl-N'-benzoylthiourea yielded the square pyramidal cationic complex [TcO(L)₂]Cl. By contrast the octahedral methoxy complex [ReO(L )₂( OMe)] was obtained when the analogous Re(V)-oxo precursor, [n-Bu₄N] [ReOCI₄], was reacted with N,N-diethyl-N'-benzoylthiourea under the same reaction conditions.
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- Date Issued: 2001
Design, synthesis and evaluation of silver-specific ligands
- Authors: Daubinet, André
- Date: 2001
- Subjects: Ligands Ligands -- Design Ligands -- Analysis Ligands -- Evaluation Silver -- Metallurgy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4308 , http://hdl.handle.net/10962/d1004966
- Description: Several series of ligands, designed to chelate silver(I) specifically in the presence of base metals, have been synthesised. The ligands include: - dithiodiamide compounds, prepared by the condensation of acetanilide derivatives with 1,2-dibromoethane; propanenitrile and propanoic ester derivatives prepared from pyridine-2-carbaldehyde via the Morita-Baylis-Hillman reaction; and novel malonamide ligands from the reaction of diethyl malonate with a range of primary amines. The malonamide derivatives were prepared under both conventional thermal and microwave-assisted conditions, the latter proving to be highly efficient. The ligands were all characterised using a combination of spectroscopic and, where appropriate, elemental analysis; in one case, the structural assignment was confirmed by single-crystal X-ray analysis. The fragmentation patterns in the electron-impact mass spectra of the malonamide derivatives have been explored using high-resolution and meta-stable peak scanning techniques. Complexes of the malonamide ligands with copper(II) and silver(I) have been synthesised, and examination of these complexes has revealed distinct differences in their co-ordination preferences towards silver(I) and copper(II). Tentative, computer-modelled structures for the complexes have been proposed using the available spectroscopic and elemental analysis data. Computer modelling, at the Molecular Mechanics level, has also been used to assess the capacity of the ligand systems to adopt conformations suitable for the chelation of tetrahedral silver(I). Solvent extraction studies have been undertaken using aqueous metal ion solutions and various organic solvents. The dithiodiamide derivatives typically presented solubility problems, but one of the ligands, N,N´-bis(3-chlorophenyl)-3,6-dithiaoctanediamide, exhibited significant but slow extraction of silver(I) into toluene. The malonamide derivatives, however, proved to be readily soluble in ethyl acetate and, in some cases, exhibited good to excellent selectivity for silver(I) in the presence of the base metals copper and lead. Atomic absorption analysis revealed rapid equilibration times (<15 min) and high extraction efficiencies over a wide pH range (2.78 - 9.0). Metal selectivity has been determined by ICP-MS analysis of the residual silver, copper and lead present in the aqueous phase after 15 min, and one of the ligands, N,N´-bis(2-benzylsulfanylethyl)malonamide, exhibits excellent (≥ 96 %) silver(I) specificity.
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- Date Issued: 2001
Ecology and breeding biology of Lanner Falcons in the Eastern Cape Province, South Africa
- Authors: Stephenson, Alan
- Date: 2001
- Subjects: Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5667 , http://hdl.handle.net/10962/d1005352 , Birds -- Breeding , Birds -- South Africa -- Eastern Cape , Birds -- Ecology , Falcons -- South Africa -- Eastern Cape
- Description: Lanner Falcons Falco biarmicus are the commonest large falcons in Africa and this study in the coastal area of the Eastern Cape Province, South Africa investigated their ecology from 1984 to 2000. Lanners have recently been categorised as near-threatened and this study was initiated to ascertain if the population was stable. Breeding success of a small population, in different habitat types, was monitored intensively from 1997 to 2000, and the factors that inhibited breeding were investigated. The earliest onset of incubation was 17 July and the latest 16 August, with 2.2 young fledged per breeding pair over the four-year period. Incubation lasted 32 days and young fledged after 42-45 days. All nest sites were on cliffs with a mean height of 114 m, a mean vertical face of 53 m; 45% of the nests were in ravens’ nests. The aspect of cliff sites also influenced breeding success. Radio tracking was used to determine home range, habitat use and hunting methods, with prey species identified. Home ranges were between 66 km² and 249 km². Preferred prey was domestic chickens, pigeons and small birds during the breeding season. Foraging ranges were smaller in intensively cultivated areas with seed crops. Data obtained from ringing returns showed that no long distance movements occurred in this region, but two juveniles dispersed 152 km and 127 km. Conservation aspects with possible threats to Lanner Falcons such as poisons, electrocutions and direct persecution are discussed with some recommendations made for future research. Evidence from this study indicates that Lanner breeding success is not limited by nest site availability, but by rainfall timing and prey availability. Lanners foraged more in open areas than areas with tall vegetation, and benefited from intensive agriculture. This population appeared to be healthy and in no danger of declining in the near future.
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- Date Issued: 2001
Effect of feeding regimen, temperature and stocking density on growth and survival of juvenile clownfish (Amphiprion percula)
- Authors: Johnston, Gavin
- Date: 2001
- Subjects: Anemonefishes , Fishes -- Feeding and feeds , Fishes -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5274 , http://hdl.handle.net/10962/d1005118 , Anemonefishes , Fishes -- Feeding and feeds , Fishes -- Growth
- Description: In aquaculture, a thorough knowledge of the specific environmental requirements of a species is needed in order to maximize growth rate and survival. There is a paucity of data regarding the fundamental environmental requirements for the ongrowing phase of clownfish juveniles. This prompted the design of three experiments to determine the best feeding regimen, temperature and stocking density that maximize growth and survival of Amphiprion percula. Ration size and feeding frequency are important factors for optimizing fish growth during the juvenile grow-out phase. A factorial growth trial was conducted to determine the effect of feeding frequency and ration size on the growth of juvenile clownfish (Amphiprion percula).Three feeding frequencies (1, 2 and 3 times daily) and six rations (2,4,6,8, 10 and 12 % body weight per day (BW.day⁻¹)) were used to test the growth response over a twelve week period. Non-linear regression analysis on the effect of ration, independent of feeding frequency, on growth resulted in a significant (n = 36; r² = 68.7) parabolic model: In y = -0.0302x² + 0.5159x + -4.4377. Maximum growth corresponded to a ration of 8.5% BW.day⁻¹. Survival as a function of ration was significantly lower at 2% BW.day⁻¹. Data were further examined with Analysis of CoVariance (ANCOVA) to determine the effect of ration on growth at each feeding frequency. The combination revealed a maximum growth rate when the fish were fed a ration of 10% BW.day⁻¹ divided into two equal meals. The required ration per meal to maintain maximum growth was also found to decrease as feeding frequency increased. The determination of the best temperature for growth is of great importance due to the direct relationship between fish metabolism and temperature. The thermal preferendum of A. percula has already been estimated at 26 ± 0.7°C but it is not known whether this closely approximates the temperature for maximum growth. Sixteen tanks were set to different temperatures ranging between 21.5 and 30.2 °C. Ten juvenile A. percula were placed in each tank and growth was measured fortnightly over the course of the 10 week experiment. Non-linear regression analysis resulted in significant models for fish length (y = -0.0005x² + 0.00267x - 0.0338; r² = 56.7, n = 11) and weight (y= -0.00016x² + 0.0084x - 0.1073; r² = 61.6, n = 11). These models predict that maximum growth would be at 27.7 and 27.1 °C for length and weight, respectively. Temperature, over the range tested, had no apparent effect on survival. There was no significant difference between the temperatures for maximum growth and the preferred temperature. The effect of stocking densities ranging from 0.2 fish.L¹ to 4.0 fish.L⁻¹ on growth were used in the third experiment. The fish were fed to satiation twice daily and growth was measured fortnightly throughout the 8 week experiment. No effects on growth, survival or coefficient of variation were found within the range of stocking densities tested.
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- Date Issued: 2001
Elements of dream interpretation: laying the foundation of a basic model for clinical practice
- Authors: Schön, Joan
- Date: 2001
- Subjects: Dream interpretation Dreams
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3050 , http://hdl.handle.net/10962/d1002559
- Description: The study addresses certain paradoxes evident in the theory and practice of dream interpretation. These relate to the considerable value afforded to dreams in psychoanalytic thinking, compared with (1) the surprising dearth of literature, research, and training on dream interpretation in clinical practice, (2) the difficulties voiced by clinicians regarding dream interpretation, and (3) the diversity of keys employed by different schools to unlock the ‘truth’ of dreams. The intention of the study is to examine these paradoxes in order to develop a model fordream interpretation which falls within the ambit of psychodynamic psychotherapy. It is argued that there have been few insights over the century to match the seminal work of Freud (1900/1976), except perhaps the work of Carl Jung. As a result of the 1914 rift between these two, Jung’s insights have been largely ignored in mainstream psychoanalytic thinking and the focus on dreams has given way to other areas of development, such as, unconscious thinking, symbol formation, and interpretation in a general sense. These, it is argued, have contributed to a more comprehensive understanding of dreams and their interpretation. Thus a model would need to consider both Freud and Jung’s work, and later salient developments. It would also need to be informed by local, contemporary practice. The method used in this thesis is one of breaking down the process of dream interpretation into component parts, in order to examine useful contributions from different sources and to compare work with dreams to work with other material. The literature review examines the major theoretical contributions in relation to four elements of dreams interpretation: the nature and function of dreams, methods of dream interpretation, the meaning of dreams, and the goals of dream interpretation. A model which accommodates diverse theories without resorting to eclecticism is then proposed. Dream interpretation is further examined in the light of a multiphase clinical study, designed to provide different perspectives on the topic. The study yielded findingscompatible with the literature reviewed, as well as certain problems in relation to the proposed model. These included shortcomings of the elements used in the literature review, particularly the sequence of these elements, and caveats about affording dreams a special focus in the consulting room. Thus a second configuration was posited, namely the idea of viewing dream-work as a triangular situation, comprising the dream, the dreamer, and the dream interpreter. The final model which is the outcome of the study provides two interrelated methods of addressing dream interpretation which accommodate the theory/practice dichotomy. In the first, the elements of dreams and their interpretation are considered sequentially. This method provides a framework for considering theoretical contributions on dreams, as well as issues of technique, without recourse to the introduction of theory in the consulting room. In the second, dream interpretation is regarded as a triangular situation, comprising the interchange between therapist and patient in relation to the patient’s dream-life. This structure accommodates the alliance which is discernible in practice and draws on Segal’s (1957/1986) notion that the process of symbol formation is a triangular situation. The value of regarding ‘dream-work’ in the consulting room as a triangular situation is threefold: (1) it is akin to symbol formation in terms of the meaning reached; (2) dreams cannot be accurately interpreted in isolation from the contributions of both therapist and patient; and (3) it provides ‘dream-work’ in practice with its own structure, highlighting a perspective that dreams are an element of clinical practice, rather than a focus, a subtext within the broader framework of psychodynamic psychotherapy.
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- Date Issued: 2001
Environment as integrating organiser: a case study of curriculum 2005 in KwaMhlanga, South Africa
- Authors: Khumalo, Four-Ten Enock
- Date: 2001
- Subjects: Competency-based education -- Research -- South Africa Curriculum planning -- South Africa Environmental education -- Curricula -- South Africa -- Mpumalanga Environmental education -- Curricula
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1511 , http://hdl.handle.net/10962/d1003393
- Description: Curriculum 2005 is an attempt by the South African government to create and implement a strategic plan to change the formal school curriculum. The new curriculum has 'integration' as one of its focal features. This study is an investigation of the use of' environment' as an integrating' organiser' in the senior phase of Curriculum 2005 in a selection of schools in the Mpumalanga province. While the Curriculum 2005 framework encourages curriculum integration, this is an area which might be neglected during implementation, because there is so little experience among teachers of working in an 'integrated' way. Environmental education is an approach to education which requires and facilitates curriculum integration. This study has the potential to contribute to our understanding of the integration of environmental learning across the new curriculum. Questionnaires and vignettes based on document analysis, follow-up interviews and classroom observations, involving a small group of teachers, were used in conducting the study. The investigation has revealed that participating teachers show a limited understanding of the constructs 'environment' and 'phase organiser'. Teachers do not take or introduce a critical perspective on the nature and causes of environmental issues. They treat the construct 'environment' and associated issues quite superficially when working with learners. Participating teachers generally misunderstood the concept 'phase organisers' and tended to interpret it in concepts associated with the curriculum framework they were used to. Curriculum 2005 also requires teachers to take on a more active curriculum development role. This study looked at four teachers' attempts to develop learning programme units, and at the way in which two teachers implement their curriculum plans focussing on 'environment', in the classroom. It was found that participating teachers do not always follow the same sequence or steps when developing a learning programme. Learning programme units were not considered in developmental sequence, they lacked some form of continuity and links between intended learning outcomes and teaching activities were also lacking. There was inadequate integration between learning areas. Furthermore, integration between knowledge, skills, values and attitudes was also not quite clear among the teachers, and they tended to deal with environmental knowledge in a rather limited way, focussing instead on the awareness and attitudes. These findings are of concern, and they are in keeping with the Curriculum 2005 Review Report, which highlighted the danger of inadequate focus on curriculum content. On overall teachers seem to be struggling with the whole notion of 'integration', even though environment as a phase organiser is meant to assist with curriculum integration. The thesis ends with recommendations on how teachers might be assisted to achieve meaningful curriculum integration, through using learning outcomes as well as content knowledge relevant to environmental learning.
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- Date Issued: 2001
Enzymology of activated sewage sludge during anaerobic treatment of wastewaters : identification, characterisation, isolation and partial purification of proteases
- Authors: Tshivhunge, Azwiedziswi Sylvia
- Date: 2001
- Subjects: Sewage sludge , Sewage sludge -- Environmental aspects , Sewage sludge digestion , Anaerobic bacteria
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4012 , http://hdl.handle.net/10962/d1004072 , Sewage sludge , Sewage sludge -- Environmental aspects , Sewage sludge digestion , Anaerobic bacteria
- Description: During anaerobic digestion bacteria inside the digester require a carbon source for their growth and metabolism, sewage sludge was used as a carbon source in this study. The COD content was used to measure the disappearance of the substrate. COD content was reduced by 48.3% and 49% in the methanogenic and sulphidogenic bioreactors, respectively, while sulphate concentration was reduced by 40%, producing 70mg/L of hydrogen sulphide as the end product over the first 5-7 days. Sulphate (which is used as a terminal electron acceptor of sulphur reducing bacteria) has little or no effect on the sulphidogenic and methanogenic proteases. Sulphite and sulphide (the intermediate and end product of sulphate reduction) increased protease activity by 20% and 40%-80%, respectively. Maximum protease activity occurred on day 21 in the methanogenic reactor and on day 9 in the sulphidogenic reactor. The absorbance, which indicates the level of amino acid increased to 2 and 9 for methanogenic and sulphidogenic bioreactors, respectively. Proteases that were active during anaerobic digestion were associated with the pellet (organic particulate matter) of the sewage. These enzymes have an optimum activity at pH 10 and at temperature of 50°C. The proteases that were active at pH 5 and 7, had optimum temperatures at 30°C and 60°C, respectively. Due to their association with organic particulate matter, these enzymes were stable at their optimum temperatures for at least five hours at their respective pH. Inhibition by PMSF, TPCK and 1.10-phenanthroline suggested that proteases inside the anaerobic digester are a mixture of cysteine, serine and metalloproteases. At pH 5, however, EDTA appeared to enhance protease activity by 368% (three-fold). Acetic acid decreased protease activity by 21%, while both propionic and butyric acid at 200 mg/L cause total inhibition of protease activity while these acids at higher pH (where they exist as their corresponding salts) exerted little effect. Copper, iron and zinc inhibited protease activity by 85% at pH 5 with concentrations ranging between 200 and 600 mg/L. On the other hand, nickel, showed an increase in protease activity of nearly 250%. At pH 7 and 10, copper had no effect on protease activity while iron, nickel and zinc inhibited these enzymes by 20-40%. Proteases at pH 7 were extracted from the pellet by sonication, releasing 50% of the total enzymes into the solution. The enzymes were precipitated by ammonium sulphate precipitation, and further purified by ion exchange chromatography and gel filtration. Ion exchange chromatography revealed that most of the enzymes that hydrolyse proteins are negatively charged while gel filtration showed that their molecular weight is approximately 500 kDa.
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- Date Issued: 2001