Interest rate liberalisation and economic growth in SADC countries
- Authors: Moyo, Clement Zibusiso
- Date: 2018
- Subjects: Southern African Development Community , Economic development -- Africa, Southern Developing countries -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/22791 , vital:30087
- Description: The pioneers of financial liberalisation, McKinnon (1973) and Shaw (1973) argue that inter-est rates determined by market forces have a positive effect on economic growth rates. Inter-est rates that are kept at low levels through the intervention of a central bank discourage sav-ings and capital accumulation, and distort the allocation of resources. Interest rate liberalisa-tion results in higher real interest rates which could have a positive effect on savings, invest-ments and economic growth (Ang & McKibbin 2007). Interest rate liberalisation also reduces capital flight and encourages capital inflows by increasing return for investors which supple-ments domestic investments. Shaw (1973) argued that interest rate liberalisation promotes financial development by encouraging savings and increasing the availability of funds for lending purposes. The study provides an empirical analysis of the channels through which interest rate liberalisation impacts on economic growth in SADC countries for the period 1990 to 2015. The study is motivated by the concerns on the impact of interest rate liberalisation on eco-nomic growth in the period after the 2008-’09 global financial crisis as well as concerns that interest rate liberalisation increases the likelihood of financial crises. Higher interest rates resulting from interest rate liberalisation may increase the likelihood of financial crises by encouraging risk-taking on the part of banks in an attempt to take advantage of higher returns. Authorities in most countries have reduced interest rates in an attempt to boost aggregate demand, which is expected to speed up the recovery from the crisis. However, the lowering of interest rates may result in a decrease in savings and investments, which are the main drivers of long-term economic growth. Real interest rates below equilibrium may encourage banks to take more risks in their lending practices in order to earn higher returns which may result in an increase in non-performing loans. The influence of interest rates on financial crises has thus received considerable attention since the onset of the 2008-’09 global financial crisis and this thesis contributes to the literature by determining how interest rates impact on economic growth in SADC countries and whether interest rate liberalisation increases the likelihood of financial crises. The study examines the relationship between interest rate liberalisation and economic growth through different channels. These include savings and investments, capital flows and finan-cial development. The study uses the Pooled Mean Group (PMG) estimator proposed by Pesaran et al (1999) to estimate the effect of interest rate liberalisation on economic growth through the abovementioned channels. The study also examines whether interest rate liberalisation increases the likelihood of financial crises. This is estimated using the logit model, due to the binary nature of the dependent variable. The results provide limited support for the McKinnon and Shaw hypothesis. Interest rate liberalisation has a positive effect on economic growth through higher savings and investments. Interest rate liberalisation has a positive outcome on capital inflows, which indicates that the prospect of earning higher returns encourages foreign investors to invest in the domestic economy. However, capital inflows do not enhance economic growth. This could be due to the low levels of human capital in SADC countries. Interest rate liberalisation boosts financial development through higher savings and invest-ments. However, financial development has a negative effect on economic growth because of the link between financial development and financial crises. The results show that interest rate liberalisation decreases the likelihood of financial crises directly, however, it increases the probability of financial crises indirectly through financial development. This suggests that the major cause of financial crises in the region is the low levels of institutional quality and lack of adequate supervisory frameworks to monitor the functioning of the financial system. Therefore, the results imply that the negative impact of interest rate liberalisation may outweigh the positive effect of higher savings and investments in SADC countries. A number of policy recommendations can be drawn from the study. Liberalisation of interest rates has a positive effect on economic growth through savings and investments. However improving the levels of institutional quality is vital for preventing financial crises. Interest rate liberalisation may not have a direct influence on financial crises, but higher levels of fi-nancial development emanating from higher interest rates increase the likelihood of financial crises. Therefore, a sound monitoring framework is necessary for the benefits of financial liberalisation to be realised. Also, investment in education, training and research and development is a necessity so as to increase levels of human capital, which in turn may allow the region to reap the benefits of capital inflows.
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- Date Issued: 2018
Investigating combinations of feature extraction and classification for improved image-based multimodal biometric systems at the feature level
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
Investigating the experiences of grade 8 English first additional language learners within an English home language classroom: a case study
- Authors: Abader, Naadirah
- Date: 2018
- Subjects: Language and languages -- Study and teaching -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: http://hdl.handle.net/10948/22662 , vital:30050
- Description: Teaching English home language (EHL) to a classroom of learners who are predominantly from another mother tongue context is a complex process because of the challenges faced by the learners. They struggle to cope with the demands of the EHL classroom, especially when their mother tongue is not recognized within the classroom context, as they move between different linguistic spaces. Despite their diverse identities, English language teachers continue to apply the linguistic approach of English only. This study was aimed at investigating the ways in which the experiences of non-mother tongue speakers in the EHL classroom affect the identities of these learners. Through a qualitative approach using photovoice with learners an attempt was made to probe their experiences of bringing other languages into an English home language classroom. Participants included 33 Grade 8 learners and their four English teachers from Taah High School in Nelson Mandela Bay. The findings have implications for the way in which diverse linguistic learners are taught in an EHL classroom, as the space that caged and rendered learner participants voiceless because they are not allowed to draw on their mother tongue linguistic repertoires, were changed. Learners mentioned that their teachers do not acknowledge the identity that each of them brings to the classroom.
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- Date Issued: 2018
Investigation of the potential separation of isomers and related compounds using host compound (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol
- Authors: Pohl, Pieter Lourens
- Date: 2018
- Subjects: Chemistry, Organic , Clathrate compounds Thermal analysis
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23131 , vital:30432
- Description: In this study, we investigated the potential of a host compound, (2R,3R)-(−)-2,3-dimethoxy-1,1,4,4-tetraphenylbutane-1,4-diol (DMT), for use in the separation of isomers and related compounds using host-guest chemistry. The title molecule, DMT, is composed of a butane chain bearing hydroxyl moieties on the terminal carbons and methoxy moieties on the two internal, chiral carbon atoms. In addition, there are two phenyl rings on each of the terminal carbons. The synthesis of DMT was carried out by subjecting the diester of naturally-occurring optically active tartaric acid to a Grignard reaction employing phenylmagnesium bromide. Subsequent methylation of the secondary hydroxy groups with dimethyl sulfate afforded DMT. The resulting host molecule was investigated for its inclusion abilities by crystallizing with a number of potential aromatic, aliphatic and alicyclic guests such as toluene, aniline, nitrobenzene, anisole, cyclohexane, ethyl acetate and ethanol. Host:guest ratios were determined by means of 1H-NMR spectroscopy. Of the hosts investigated, DMT favoured a host:guest ratio of 2:1 for all included guests investigated. It complexed with most non-polycyclic aromatic guests as well as cyclohexane, cyclohexene and cyclohexanone. It was not able to include short chain or branched alcohols such as methanol, ethanol or 2-propanol, or other hetero-aliphatic or hetero- cyclic compounds such as diethyl ether, acetonitrile, morpholine or dioxane. Competition inclusion experiments were performed in which DMT was crystallized from equimolar and non-equimolar binary, ternary and quaternary mixtures of appropriate guests. The mother liquor mixtures and resultant crystals were subjected to GC-MS analysis in order to determine whether DMT showed discriminatory behaviour towards the guests from a mixture. It was observed that DMT was able to differentiate between related compounds, for example, the host preferred to include N,N-dimethylaniline compared with N-methylaniline and aniline. The host also discriminated against isomers, for example, p-xylene was preferentially included over o-xylene and m-xylene, while o-cresol was included in preference to p-cresol and m-cresol. Single crystal X-ray analysis was used to investigate the host–guest interactions responsible for guest inclusion, as well as to discern reasons for the host’s selective behaviour. X-ray data for the inclusion complexes indicated that each complex was isostructural, crystallizing in the monoclinic C2 crystal system. A pair of 1,3- and 2,4- intramolecular hydrogen bonds, as well as intramolecular non-classic hydrogen bonds between adjacent ortho-aromatic hydrogens and hydroxy moieties was a significant stabilizing factor for the geometry of the host. Guests were held within discrete cavities in the crystal lattice, and experienced only π–π stacking, CH–π interactions and other short contacts. Thermal analyses were used to determine the relative thermal stabilities of the complexes, and these data compared to the selectivity preference of DMT, obtained from the competition experiments, in order to assess the reasons for any discriminatory behaviour. Finally, Hirshfeld surface analysis data was used to determine if the thermal stability of the complexes was related to the number and type of interactions between host and guest.
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- Date Issued: 2018
Investigation of the thermo-chemical behaviour of coal-algae agglomerates
- Authors: Baloyi, Hope
- Date: 2018
- Subjects: Biomass energy , Coal -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23913 , vital:30642
- Description: There is a growing research interest in the co-processing of biomass and coal, with the aim of addressing the negative attributes associated with the thermal processing of coal alone. Biomass feedstocks are regarded as a clean, renewable source, and the co-utilization of biomass feedstocks with coal is deemed to have a potential to reduce emission of pollutants (i.e. NOx and SOx) and volatile organic compounds (VOC’s). Moreover, biomass are thermally reactive and thus facilitate the conversion of coal during co-processing. Biomass material and coal are two autonomous fuel materials with different chemical characteristics and have a dissimilar thermal behaviour making it difficult to achieve chemical interaction between the two solid fuels to contribute to the formation of products. Coalgae® Technology developed at the Nelson Mandela University, involves the biological treatment of coal fines by adsorbing live microalgae biomass (in slurry form) onto waste coal fines to form coal-microalgae agglomerates. This new innovative approach seeks to integrate bio-based feedstock into coal thermal processing and to improve the utilization and thermal efficiency of coal fines as well as the interaction between the volatile components of biomass and coal during thermal processing (e.g. devolatilization), thereby overcoming some of the challenges that confront the co-processing of coal and biomass. Coal fines are low-ranked coals, generally characterized by high contents of sulphur, high ash yields, low calorific values and poor thermal reactivity, and these attributes limits the thermo-chemical processing of the coal fines. Therefore, this investigation was undertaken to assess the thermo-chemical behaviour of coal-microalgae agglomerates, formed by adsorbing live microalgae slurry at varying ratios onto coal fines. For this purpose, the effects of adsorbing microalgae at varying ratios on the chemical characteristics and thermal behaviour of coal fines under pyrolytic conditions were investigated. The primary aim was to assess whether the thermo-chemical behaviour of coal-microalgae agglomerates, formed by adsorption of live microalgae onto fine coal, is substantively modified compared to a simple additive model of the original coal and pre-dried microalgae biomass samples. Results obtained from the proximate analyses performed on an Eltra Thermo-gravimetric analyzer (TGA) thermostep, have shown that the adsorption of microalgae slurry onto coal fines does not possess greater influence in improving the yield of volatiles and ash in coal fines than can be expected from a simple additive model of the original raw materials. Based on the ultimate analyses results, it was found that the adsorption of microalgae slurry resulted in a systematic reduction in the sulphur content, a notable increase in the hydrogen and oxygen contents, however, no significant disparities were found between the measured ultimate properties of coal-microalgae agglomerates as compared to the theoretically-expected ultimate properties from a simple linear combination of parental coal and microalgae biomass. Assessment of the thermal behaviour of parental samples and coal-microalgae agglomerates involved the use non-isothermal (40-900ºC, 20 K/min) thermogravimetry under inert conditions. It was found that the adsorption of microalgae slurry onto coal fines resulted in an improved thermal reactivity of coal fines, although, did not affect the overall pyrolysis characteristics of the coal fines. Comparison of the thermal profiles (measured and calculated TG/DTG curves), revealed that the yield of volatile products during the pyrolysis of coal-microalgae blends do not exceed the expected volatile yields from a simple combination of coal and microalgae biomass. These results suggest that there was no positive or accelerative synergistic interaction between volatile components of adsorbed microalgae and coal fines during pyrolysis. Mild pyrolysis of raw coal and coal-microalgae performed in a fixed-bed reactor furnace (450ºC), resulted in improved yields of Fossil-Bio crude (FBC) oil (derived from coal-microalgae pyrolysis), at increased biomass ratio compared to coal tar. FBC Oil was found to contain relatively high contents of oxygen, hydrogen, and low sulphur content than coal tar. GC-MS analyses showed the presence of a heterocyclic compounds (i.e. Indole and 2, 6 dimethyl pyridine) in the FBC oil and these were not identified in the coal tar. Furthermore, high boiling compounds such as Flourene, pyrene and pentacosane were identified in the coal tar, however not identified in the FBC oil. Simulated distillation results showed notable differences between the FBC oil and coal tar in terms of the distribution of boiling point fractions particularly, high boing point components. Semi-devolatilized chars derived from coal-microalgae agglomerates showed substantial degree of decarboxylation and dehydrogenation compared to the coal chars.
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- Date Issued: 2018
Key considerations for novel aptamer generation and aptasensor platform design: a case study on human α-thrombin and histamine as sensor targets
- Authors: Ho, Lance St John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63534 , vital:28432
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Knowledge and knowers in Educational Leadership and Management (ELM) Master’s Programmes in South Africa
- Authors: Kajee, Farhana Amod
- Date: 2018
- Subjects: Educational leadership -- South Africa , Teachers -- Training of -- South Africa , Education, Higher -- South Africa , Master of education degree -- South Africa , Knowledge, Theory of , Educational sociology -- South Africa , Education, Higher -- Aims and objectives -- South Africa , Legitimation Code Theory (LCT)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60698 , vital:27819
- Description: This dissertation examines the knowledge and knower practices in the Master’s in Educational Leadership and Management (ELM) coursework programmes at South African public universities. This study was prompted by my growing awareness of problems and tensions in the field of ELM generally, and at the level of programme design of the M Ed degree in particular. Many of these had been identified by a national audit of coursework M Eds in ELM (CHE, 2010), and this study sought to find a way of theorising these with a view to improving both course design and teaching. To this end I employed Maton’s Legitimation Code Theory (LCT) which enables critical engagement with knowledge and knowers in programmes, how they are positioned, and how this positioning may be problematic. Hence my first research question sought to discover and critique what counted as knowledge in these programmes and why, while the second asked how knowers were positioned, and why this had come to be the case. LCT has its roots in the work of Bernstein and Maton, whose preoccupation with curriculum was/is driven by a sense of social justice: if we can understand how and why the curriculum is organised and presented in a particular way, it becomes possible to re-imagine teaching and learning, making it accessible to a broader, more inclusive body of learners. The study also drew on critical realism as an underlabourer. This philosophy provided a nuanced understanding of ontology, encouraging and enabling me, as researcher, to unearth causal mechanisms driving the status quo. Only seven South African universities currently offer the coursework option of a Master’s degree in ELM, compared to thirteen when the audit was conducted in 2010. Six of the universities agreed to take part in the study. Data was gathered through content analysis of the six course outlines and interviews with individual co-ordinators or academics centrally involved in the programmes. Through the development of a translation device I was able to establishing that a knower code was dominant in the programmes. Using this point as my departure, I interrogated the knowledge practices and found that different types of knowledge were being privileged across the programmes, with some having a practical/professional leaning and others a more academic/theoretical orientation. The resultant tension does, I argue, restrict knowledge building and helps to account for the fact that the field is generally considered to be under-theorised. The fact all of these programme are registered with the same national qualifications authority, ostensibly following the same national guidelines for Master’s degrees is worrying. The study attempts to find underlying, historically significant reasons for this unevenness. An analysis of the programmes revealed a leaning towards supportive pedagogical approaches. While all programmes promote a cultivated gaze their purposes are not always the same. While a hegemonic practices potential for opening counts as knowledge, cultivated gaze can enable transformation, it can also encourage that can impede real change and empowerment. The study has the up much needed debate on what is meant by a Master’s in ELM, what and what kinds of knower are envisaged.
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- Date Issued: 2018
Knowledge practices and student access and success in General Chemistry at a Large South African University
- Authors: Mtombeni, Thabile Nokuthula
- Date: 2018
- Subjects: Chemistry -- Study and teaching (Higher) -- South Africa , Knowledge management , Education, Higher -- Curricula -- South Africa , Critical realism , Social integration -- South Africa , Educational equalization -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62873 , vital:28305
- Description: This dissertation reports on an investigation into the structuring principles of the General Chemistry curriculum at a Large South African University (LSAU). Student learning in the introductory modules of General Chemistry is critical for access to a range of fields since it is a requisite course for a variety of degree programmes. However, there is ample evidence that success in this subject remains a major challenge, particularly for black students. My quest in this study was to explore how the curriculum could enable greater epistemic access and thus include more students in science programmes at the LSAU. I investigated the organising principles underlying the curriculum practices of the General Chemistry module and explored the effects of the curriculum structure on student learning. Theoretically and conceptually, the study was underpinned by a social realist approach which holds that knowledge is stratified, differentiated, and has real emergent properties, powers and effects. The research question that I attempted to answer in this study was: How do knowledge practices privileged in the General Chemistry curriculum at the LSAU enable or constrain student learning? I adopted an intensive research design approach to conduct a qualitative case study using social realism and LCT as theoretical and analytical lenses. I used empirical data such as curriculum documents and interviews with lecturers to uncover the underlying generative mechanisms of the curriculum. I adopted a multi-layered data analysis process to make visible the underlying organising principles informing knowledge practices in the curriculum so that I could explain their potential effects on student learning. The first level of analysis explored the context of the curriculum and associated knowledge practices, and examined the pedagogic discourse evident in the curriculum. The second level of analysis revealed the inner logic structuring the curriculum and the associated knowledge practices. I used Maton’s Legitimation Code Theory (LCT): Specialisation to identify the specialisation codes, gazes and insights generated by the curriculum. For the third level of analysis, LCT: Semantics was used to generate the semantic profiles of learning activities to determine the extent to which the curriculum structure made cumulative learning possible. From the findings, it is evident that the verticality of knowledge in General Chemistry points to a recontextualising principle that prescribes the selection and arrangement of knowledge, and the special relationship of actors and discourses. As a result, the strong framing of the instructional discourse of General Chemistry curriculum structure is likely to constrain epistemological access for large numbers of students. In order to improve epistemological access to the field, weaker framing of the instructional discourse in introductory science is necessary. Weaker framing of the General Chemistry curriculum would require, in particular, changes to pacing, and that the evaluative criteria are made explicit. This is especially necessary when certain abstract and complex curricular content is taught, especially in the first semester. The findings also indicate that the nature of the organising principles in the curriculum are significant for improving epistemological access to knowledge. In terms of LCT: Specialisation, the General Chemistry curriculum generated a knowledge code and downplayed differences among social categories of students, thus positioning all equally in relation to the knowledge and practices of the field. Therefore, the structuring of the curriculum emphasises and legitimates students who have attained specialist knowledge without considering the nature of the new student coming into the educational setting. Simply, what is privileged is both the object of study (theoretical knowledge) and how it is studied (procedural knowledge). This finding is in line with the general outcomes of Chemistry education. In addition, the purist insight generated by the curriculum further attests to where the emphasis is placed in the curriculum. I argue that the lack of social relations in the curriculum poses a challenge for the holistic development of students as science knowers. The analysis of the learning activities shows rapid code shifts that indicate changes in cognitive demand and modes of thinking required of students. I argue that signposting the changes in complexity of knowledge and in the mode of thinking required could make learning, and thus epistemological access, more possible. Given the imperative of access to powerful knowledge, I contend that the curriculum should be reshaped to enable epistemological access for more students.
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- Date Issued: 2018
Labour dispute resolution in Kenya: compliance with international standards and a comparison with South Africa
- Authors: Gathongo, Johana Kambo
- Date: 2018
- Subjects: Dispute resolution (Law) -- South Africa Mediation and conciliation, Industrial -- South Africa , Dispute resolution (Law) – Kenya , Mediation and conciliation, Industrial -- Kenya , Arbitration, Industrial -- South Africa , Arbitration, Industrial -- Kenya
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: http://hdl.handle.net/10948/23980 , vital:30657
- Description: The thesis examines the effectiveness of the Kenyan labour dispute resolution system by undertaking a comparative analysis of South African and international labour standards. A comparative approach is adopted, which relies on primary and secondary sources of data, thereby undertaking an in-depth content analysis. The study provides a comprehensive discussion of the current legislative provisions and alternative dispute resolution (ADR) framework as recognised in both countries' national labour legislation as well as in a number of international labour standards instruments. In particular, the study illuminates and discusses the bottlenecks in the current Kenyan system and argues that it does not adequately respond to the needs of parties in terms of the international labour conventions. The study argues further that labour disputes should be resolved as quickly and informally as possible and at the lowest level possible. Similarly, disputes should ideally be resolved with little or no procedural technicalities, and without allowing them to drag on indefinitely. However, this study observes that there have been notable concerns in the current dual system of labour dispute resolution in Kenya. The problems include protracted referral timeframe for dismissal disputes, non-regulation of maximum timeframe for the agreed extension after 30 days conciliation period has lapsed, the absence of a statutory timeframe for appointing a conciliator/commissioner and arbitration process under both the Labour Relations Act, 2007 and the Employment Act, 2007. The study argues for Kenya to incorporate provisions in its labour laws of a proactive and expeditious dispute resolution thereby helping to resolve labour disputes in the most effective and efficient manner without necessarily having to resort to the courts. Likewise, the responsibility of resolving statutory labour disputes in Kenya is still heavily under the control of the government of Kenya through the Ministry of Labour. There is still no independent statutory dispute resolution institution (Conciliation, Mediation Commission) as envisaged by the Labour Relations Act, 2007. As a result, the Kenyan dispute resolution system has been criticised for lack of impartiality leading to the increases in strikes and lockouts. Similarly, it has made the attainment of effective and efficient labour dispute resolution difficult. In view of that, a comparative approach with South Africa is adopted with a view to informing Kenya how the establishment of independent institutions similar to the Commission for Conciliation Mediation and Arbitration, Bargaining Councils and specialised labour courts can lead to effective dispute resolution in Kenya. Given above, the study provides a wide range of remedial intervention intended to address the gaps and flaws highlighted in the study. Systematically, the study provides important suggestions and possible solutions for a better institutional framework and processes to address them. However, the study acknowledges that making effective and efficient labour dispute resolution a reality calls for renewed commitment from government and social partners and investment in appropriate human and financial resources. This requires a strong political will as well as concerted efforts from all role players in the labour relations community in the two respective countries.
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- Date Issued: 2018
Laccase production by selected bacteria species isolated from some aquatic and terrestrial milieu of the Eastern Cape : applications in wastewater treatment
- Authors: Unuofin, John Onolame
- Date: 2018
- Subjects: Laccase Sewage -- Purification -- Biological treatment Water -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9626 , vital:34810
- Description: Aromatic pollutants are a diverse group of chemicals which are continuously produced from industrialization, urbanization and sophistication in technological advancement. Pristine water source polluted by these chemicls makes the water unsafe for human consumption, and as well disrupts the trophic structure of the aquatic milieu. Physico-chemical treatment techniques employed so far have been accompanied by major drawbacks which have overriden the relative successes recorded, hence, greener, simpler and more efficient methods of pollutant transformation is imperative. The prospect of enzymatic treatment of pollutants has gradually been receiving growing attention in contemporary times due to the their environmental friendliness and production economic feasiblity. Laccase, a multicopper oxidase has heightened its appeal towards environmental and biotechnological applications due to its broad substrate specificity and its requirement of atmospheric molecular oxygen as a cosubstrate and the discharge of water as the byproduct. Hence, this present study was designed to evaluate the biotechnological potentials of laccases produced by some bacteria species from some aquatic biomes of the Eastern Cape Province, South Africa. The laccase-producing bacteria were isolated from selected environmental samples by selective enrichment using selective aromatic compounds as sole carbon source and subsequently, laccase-screening phenolic substrates. The laccase-producing bacteria were identified by molecular techniques as proteobacteria belonging to the following genera: Achromobacter, Bordetella, Citrobacter, Pseudomonas and Stenotrophomonas. Optimisation of laccase production in a submerged fermentation was by traditional and statistical methods, where four isolates (Hb9c; Achromobacter xylosoxidans HWN16, Hb16c; Bordetella bronchisepta HSO16, Berl11b2; Stenotrophomonas maltophilia BIJ16, Ie1c; Citrobacter freundii LLJ16) were evaluated for the fermentative production of laccase from lignocellulosic agroindustrial residues. Predictions from statistical optimisation showed that weakly acidic conditions (pH 5) and low agitation speed (100 rpm) were required for maximum laccase production from mandarin peelings (0.5 g/200 mL) and NaNO3 (0.25 g/200 mL) in Hb9c, maize stover (0.50 g/200 mL) and NaNO3 (0.050 g/200mL) in Berl11b2 while a lower agitation speed (50 rpm) was required for maximum laccase output from 2.0 g/200 mL maize stover and 0.050 g/200 mL KNO3 in Ie1c. However, 2.50 g/200 mL wheat bran, 0.050 g/200 mL yeast extract and 50 rpm agitiation under acidic conditions (pH3) yielded maximum laccase titres in Hb16c. Further characterisation of Hb9c and Ie1c laccase secretions portrayed their polyextremotolerant capacities. They were active at a broad range of tempertaure (0-90 degreesC); with optima at 70°C (Hb9c) and 60°C (Ie1c), pH (3-11); with optima at pH 6 (Ie1c) and pH 8 (Hb9c), respectively, and were equally thermo- and pH-stable. Their activities were either improved or left unabated by high concentrations of cations, detergents, and chloride. In addition, catalytic activities of Hb9c and Ie1c laccase secretions increased when they were preincubated with 2 – 20 percent of fluoride, a potent inhibitor. Consequently, a molecular perspective depicted the isolates to have multiple homologous laccase encoding genes. The enzymes were successfully immobilised on solid supports comprising gelatin and Na-alginate with a recovery of cca. 85 percent residual activity after 8 cycles of oprertional stability experiments. The immobilised laccases were remarkable in the decolourisation of synthetic dyes, albeit, free forms also elicited satisfactory performances. Ultimately, the application of free laccases in denim bleaching, individually or with a blend of a mediator, ABTS, showed that denim colours could be bleached without the need for chemical bleaching agents. The results obtained suggest the bacteria laccases produced from lignocellulosic wastes may serve as potent degraders of phenolic pollutants in water and, may also contribute to the bioeconomy and promote greener techniques for industrial applications.
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- Date Issued: 2018
Left-invariant optimal control problems of the Engel group: classification, stability, and integration
- Authors: McLean, Catherine Eve
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62949 , vital:28323 , http://doi.org/10.21504/10962/62949
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Linking people’s needs, preferences and values to ecosystem services provided by marine phytoplankton of Algoa Bay, South Africa
- Authors: Snow, Bernadette
- Date: 2018
- Subjects: Marine phytoplankton -- South Africa -- Port Elizabeth , Marine biology -- Research Biodiversity conservation -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/33363 , vital:32669
- Description: Marine, coastal and ocean development has gained impetus around the globe and in particular along Africa’s coastal states. A socio-ecological systems framework approach was adopted to explore marine and coastal socio-ecological systems in Algoa Bay, situated in the Eastern Cape, South Africa a Bay with a rich history steeped in culture and diversity. Phytoplankton biodiversity was determined for the Bay to characterise aspects of the marine environment in Algoa Bay. The policy landscape for South Africa was also analysed to characterise the governance landscape and identify if the policies, legislation and frameworks adopted and applied would support socio-ecological systems thinking and support equitable development of marine and coastal resources. Positives raised by manager are the general positive attitude and pro-environmental value system. To understand how people within the Nelson Mandela Bay Municipality value the marine and coastal environment, their knowledge of phytoplankton and services provided, governance knowledge, attitudes towards the future of the socio-environment landscape and value positions that would identify pro-environmental behaviour of the communities surveyed. Loss of marine and coastal environments and services would be a direct threat to spiritual and cultural practices and beliefs of the amaXhosa. Further access was a driving theme in this study and therefore development and conservation efforts need to heed the value and importance of having access to the marine and coastal environment, not only for sustaining livelihoods but for religious and leisure experiences. Size fractionated biomass was determined to describe the contribution of different cell size assemblages to the overall productivity of Algoa Bay. The analysis showed a general dominance of microplankton cell sizes with the picoplankton not contributing much towards the overall biomass of the period analysed. Cell size of the phytoplankton species provides an indication of the environmental changes, together with contribution towards biomass. Species that bloom also change the productivity of the system, for example a diatom bloom will increase productivity more so than a dinoflagellate bloom. Cell size will influence response of phytoplankton to environmental changes and how phytoplankton adapts physiologically to stressors such as climate change. However in the context of studies linking biodiversity to a socio-ecological framework, size fractionated data is not required and overall productivity and diversity of the system is better suited for this type of study. The direct link between the ecological and social data is the application of the information for management of the ecosystem and as an early warning system. The information learnt from the managers and community also highlights the need for a shared approach to gathering knowledge and learning about the world around us.
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- Date Issued: 2018
Livelihood and unemployment transitions : drivers and effects on welfare in Nigeria
- Authors: Fashogbon, Ayodele Emmanuel
- Date: 2018
- Subjects: Social service -- Nigeria Social problems -- Nigeria Nigeria -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9176 , vital:34302
- Description: Hunger, unemployment and social crisis are increasing in Nigeria. Statistics supports it that most of the able-bodied youth, both male and female, are not in employment, school or training in Nigeria while poverty rate is as high as a decade ago. A number of research efforts have looked at the micro and macroeconomic paths of the problem with less attention on dynamism of unemployment vis-a-vis the labour market transition, hence this study. This study investigates dynamism of labour market by assessing pattern and transition in labour market and out of labour, as well as determining the effect size of households head’s unemployment on household welfare. To achieve this objective, the General Household Survey (GHS) panel data for 2010/211 and 2012/2013 for Nigeria was used coupled with panel regression analyses to identify determinants of transitions from unemployment to productive sectors, and determinants of transition from productive sectors to unemployment, as well as effect of unemployment on household welfare while controlling for potential endogeneity in unemployment. Across the productive sectors and between 2010 and 2013, the descriptive results of transition show that workforce in the services sector (68 percent) are the most persistent, followed by agriculture (59 percent) and least is mining and manufacturing (44 percent). Transition from nonemployment occurred the most to services sector (22 percent), followed by out-of-labour force (18 percent), agriculture (15 percent) and least to mining and manufacturing (5 percent). Further, the results show that there are both locations and gender differences in the extent of transitions in the labour market. The econometric analyses reveal that job search characteristics, age, educational levels, gender, family ties, locations and time significantly determine transition from unemployment to productive sectors (agriculture or non-agriculture). Likewise, job characteristics, demographic variables, social network, location and time significantly determine switch from one productive sector to another or to unemployment. Moreover, it explicitly reveals as well from the analysis that household head month of unemployment reduces household total consumption and food consumption by 6.4 percent with gender and sectorial differences. The study recommends a combined and swift intervention on three sides: one, there is a need to stimulate education either through scholarship, or adult education from both public and private sectors; two, need to create jobs for youth to reduce potential social and economic crisis; and lastly there is a need to provide social support either in terms of public workfare, skills for jobs and unemployment benefits.
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- Date Issued: 2018
Local tourism governance of destination marketing organisations
- Authors: Bartis, Hugh Henry
- Date: 2018
- Subjects: Place marketing Tourism -- Marketing
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/17799 , vital:28455
- Description: Globally tourism is one of the biggest industries and its role is considered key in economic development. In South Africa, tourism is one of the main economic drivers. Thus, tourism contributes to the gross domestic product, generates foreign exchange and provides sustainable employment opportunities. In order to facilitate local economic development (LED), local destination marketing organisations (DMOs) need to ensure that their operations are geared towards optimising the economic advantages related to tourism growth and development. As a result the DMOs must be strategic and well-managed. One way of achieving this is to ensure that the board of directors and specifically the non-executive directors (NEDs) practise good governance. In South Africa, three (3) types of DMOs are found, namely those that are funded by local government and incorporated into the municipality. The second type of DMOs is funded by the private sector. The third type of DMOs is those funded by both the local government and the private sector. In this case, the DMO has an agreement with the local government in terms of what their mandate is and what the agreed outcomes would be. A board of directors, comprising both executive directors (EDs) and nonexecutive directors (NEDs) is responsible for the governance of the local DMO. The main research problem of the study is the attributes and experience of the nonexecutive directors that serve on the boards of DMOs in accordance with developmental standards of best practices. In order to address the main problem, the following research objectives were formulated: To identify best practice by examining the literature as to how NEDs are prepared to serve on boards of both listed and non-listed organisations. To determine whether any policy frameworks provide guidance to NEDs serving on DMOs in South Africa. To examine whether any training or preparatory programmes exist specifically for NEDs in DMOs. To investigate whether NEDs should have specific attributes that would improve their governance of DMOs. To develop a set of recommendations that would assist NEDs to play a more effective role when executing their responsibilities. In order to address these research objectives, a quantitative research methodology was adopted sampling all the DMOs in South Africa that could be identified and were governed by a board of directors. For this purpose, a self-completed questionnaire was distributed to the board of directors of DMOs and specifically the non-executive directors. The results of the study indicated that no guidelines existed that DMOs could follow to better prepare the NEDs of local DMOs. Furthermore, no policy frameworks provide guidance to NEDs serving on local DMOs. The only guidelines that exist are generic guidelines of the King IV Report for NEDs of listed and non-listed organisations. In addition, Pike (2016:108) listed a number of characteristics of good governance. The study also revealed that no training or preparatory programmes exist for the NEDs of local DMOs. Finally, the study highlighted five (5) attributes that NEDs consider as critical in fulfilling their obligations. These include the empowerment of NEDs, the commitment of NEDs, communication with NEDs, job satisfaction of the NEDs and the need for NEDs to understand policy frameworks relevant to their tasks.
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- Date Issued: 2018
Long-term analysis of ionospheric response during geomagnetic storms in mid, low and equatorial latitudes
- Authors: Matamba, Tshimangadzo Merline
- Date: 2018
- Subjects: Ionospheric storms , Coronal mass ejections , Corotating interaction regions , Solar flares , Global Positioning System , Ionospheric critical frequencies , Equatorial Ionization Anomaly (EIA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63991 , vital:28517
- Description: Understanding changes in the ionosphere is important for High Frequency (HF) communications and navigation systems. Ionospheric storms are the disturbances in the Earth’s upper atmosphere due to solar activities such as Coronal Mass Ejections (CMEs), Corotating interaction Regions (CIRs) and solar flares. This thesis reports for the first time on an investigation of ionospheric response to great geomagnetic storms (Disturbance storm time, Dst ≤ −350 nT) that occurred during solar cycle 23. The storm periods analysed were 29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004. Global Navigation Satellite System (GNSS), Total Electron Content (TEC) and ionosonde critical frequency of F2 layer (foF2) data over northern hemisphere (European sector) and southern hemisphere (African sector) mid-latitudes were used to study the ionospheric responses within 15E° - 40°E longitude and ±31°- ±46° geomagnetic latitude. Mid-latitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low latitude changes especially the expansion of Equatorial Ionization Anomaly (EIA) also known as the dayside ionospheric super-fountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive ionospheric storm effect at mid-latitudes for some storm periods. In other cases (e.g 29 October 2003), Prompt Penetration Electric Fields (PPEF), EIA expansion and large scale Traveling Ionospheric Disturbances (TIDs) were found to be present during the positive storm effect at mid-latitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45± 5. A further report on statistical analysis of ionospheric storm effects due to Corotating Interaction Region (CIR)- and Coronal Mass Ejection (CME)-driven storms was performed. The storm periods analyzed occurred during the period 2001 - 2015 which covers part of solar cycles 23 and 24. Dst≤ -30 nT and Kp≥ 3 indices were used to identify the storm periods considered. Ionospheric TEC derived from IGS stations that lie within 30°E - 40°E geographic longitude in mid, low and equatorial latitude over the African sector were used. The statistical analysis of ionospheric storm effects were compared over mid, low and equatorial latitudes in the African sector for the first time. Positive ionospheric storm effects were more prevalent during CME-driven and CIR-driven over all stations considered in this study. Negative ionospheric storm effects occurred only during CME-driven storms over mid-latitude stations and were more prevalent in summer. The other interesting finding is that for the stations considered over mid-, low, and equatorial latitudes, negative-positive ionospheric responses were only observed over low and equatorial latitudes. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low latitude stations compared to other latitude regions.
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- Date Issued: 2018
Macro-prudential banking regulation, interest rate spread and the conduct of monetary policy in South Africa
- Authors: Shayanewako,Varaidzo Batsirai
- Date: 2018
- Subjects: Monetary policy Economic stabilization
- Language: English
- Type: Thesis , Doctoral , D.Com
- Identifier: http://hdl.handle.net/10353/14093 , vital:39843
- Description: The joint implementation of macro-prudential regulatory and monetary policies is necessary for modern banking systems not only to achieve optimal interest rate spread but to cushion the economy against the catastrophic effects of systemic risk. Therefore, the understanding of the interconnection between macroprudential regulation, interest rate spread and monetary policy, supported with empirical evidence, enables economies to build health and sound financial systems and achieve desirable growth rates. Thus, this study utilises the Vector Error Correction (VEC) mechanism to empirically investigate the interconnection between macro-prudential regulation, interest rate spread and monetary policy in South Africa. Quarterly time series data for the period from 1994 to 2016 was employed with the New Keynesian Dynamic Stochastic General Equilibrium (NKDSGE) model as the framework for analysis. The findings of this study suggest that a negative relationship exists between interest rate spread, macro-prudential regulation and monetary policy in South Africa. Moreover, the systems equation provided evidence that a short run causality running from macroprudential regulation to monetary policy is prevalent in South Africa. The empirical model of the study was found to be desirable as evidence of no serial correlation, no ARCH effect and non-normality in residuals was detected. Evidence from this study further suggest that interest rate spread has a dampening effect on monetary policy, but in the long-run this effect seems reversible in South Africa. As a result, this study recommends that caution should be taken on the appropriate selection of measures of macro-prudential regulation and its tool-kit as it can be used to disguise the symptoms of a lax monetary policy. This implies that the South African Reserve Bank (SARB) should sternly supervise and regulate the extension of credit by commercial banks in line with its inflation targeting monetary policy rule in order to achieve financial stability and ensure optimal interest rate spread that can stimulate the economy to growth.
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- Date Issued: 2018
Mannich base metal complexes and their thiocyanate analogues as catalysts in the oxidation of Catechol
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
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- Date Issued: 2018
Microfinace and poverty alleviation in Uganda
- Authors: Ben, Ssembajjwe
- Date: 2018
- Subjects: Microfinance -- Uganda , Economic development -- Uganda Economic assistance, Domestic Poverty -- Economic aspects -- Uganda
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23624 , vital:30588
- Description: Microfinance began in Uganda in the early 1990s as a response to the failure by formal financial institutions to extend financial services to the poor because of the high transaction costs involved. These microfinance institutions provide financial and non-financial services to the poor in order for the poor to generate incomes and consequently alleviate poverty. The advent of microfinance institutions was not accidental but rather in response to the people’s needs and they have therefore been beneficial for the people of Uganda. Because of that, several MFIs have been initiated to help the poor. Although many services are provided, the study focused on credit services. As most of the MFIs have to balance the business goal of profit maximization and the social goal of poverty reduction, the main objective of this study was to explore whether microfinance in Uganda is an effective tool for poverty alleviation. The study was conducted in four districts, namely Mukono, Mpigi, Wakiso and Luwero. Using random probability sampling, a sample of 170 was drawn from a pool of 300 MFI clients. and all of them responded. MFI officials were also interviewed. A total 136 officials were obtained from 47 MFI branches. The study used descriptive methods of analysis, a Likert scale to derive means, as well as a Principal Component Analysis technique. Analysis of variance (ANOVA) was used to detect if there were any statistically significant differences among the demographic variables used in the study. A Probit Regression Model was used to determine the impact of certain variables drawn from Principal Component Analysis (PCA) on poverty in Uganda. The results obtained proved that MFIs in general are effective in combating poverty in Uganda. Variables that are significant in poverty reduction through loan use are land, education, employment, household incomes and occupations of the respondents, loan sizes and improved livelihoods. Despite the positive impact of MFI loans in Uganda, the MFIs are faced with a number of challenges. The results from the interviews with the MFI officials indicated that MFIs are challenged by increasing competition, bad debt, multiple borrowings by clients, and information asymmetry. The study recommended reduced interest rates on agricultural, education and business loans. The public must also be sensitised about borrowing and there should be increased monitoring and supervision of clients, improved assessment of creditworthiness, and government should ensure an enabling environment and encourage group loans. Effort should be exerted to create employment opportunities. The study also recommended improvement in market intelligence and to be alert in gathering information on client profiles. it was recommended that microloan insurance and savings must be encouraged, operational costs be reduced, portfolios be expanded to increase loans and outreach must be maximised. Lastly, the thesis put forward some potential areas for further studies.
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- Date Issued: 2018
Modelling Ionospheric vertical drifts over the African low latitude region
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
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- Date Issued: 2018
Modelling plant water use of the grassland and thicket biomes in the Eastern Cape, South Africa: towards an improved understanding of the impact of invasive alien plants on soil chemistry, biomass production and evapotranspiration
- Authors: Gwate, Onalenna
- Date: 2018
- Subjects: Grasslands -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Rangelands -- South Africa -- Eastern Cape , Range ecology-- South Africa -- Eastern Cape , Rangelands -- Water-supply , Rangelands -- Weed control , Evapotranspiration , Plant-water relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54800 , vital:26617
- Description: It is imperative to understand the strong coupling between the carbon capture process and water use to sustainably manage rangelands. Woody encroachment is undermining rangelands grass production. Evapotranspiration (ET) highlights the links between ecosystem carbon capture process and water use. It forms the biggest flux of the hydrological cycle after precipitation yet it is not well understood. The Grassland and the Albany Thicket (AT) biomes in the Eastern Cape, South Africa, provide an interesting space to study the dynamics in rangelands biomass production and the associated water use. Therefore, the main purpose of this study was to contribute towards management of rangelands by understanding the dynamics in rangeland grass production and water use. To achieve this aim, the impact of Acacia mearnsii, an invasive alien plant, on soil chemical properties and rangelands grass production was investigated. This was achieved by analysing the biophysical attributes of A. mearnsii as they related to grass production. Secondly, selected soil variables that could be used as a prognosis for landscape recovery or deterioration were evaluated. In addition, aboveground grass biomass was measured in areas cleared of A. mearnsii and regression equations were prepared to help model aboveground grass biomass in areas cleared of A. mearnsi. The thesis also explored dynamics in water vapour and energy fluxes in these two biomes using an eddy covariance system. Consequently, water vapour and energy fluxes were evaluated in order to understand landscape water use and energy partitioning in the landscape. The study also tested the application of Penman-Monteith equation based algorithms for estimating ET with micrometeorological techniques used for validation. Pursuant to this, the Penman- Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) equations were applied. In addition, some effort was devoted to improving the estimates of ET from the PMP by incorporating a direct soil evaporation component. Finally, the influence of local changes in catchment characteristics on ET was explored through the application of a variant of the Budyko framework and investigating dynamics in the evaporative index as well as applying tests for trends and shifts on ET and rainfall data to detect changes in mean quaternary catchment rainfall and ET. Results revealed that A. mearnsii affected soil chemical properties and impaired grass production in rangelands. Hence, thinning of canopies provided an optimal solution for enhanced landscape water use to sequestrate carbon, provide shade, grazing, and also wood fuel. It was also shown that across sites, ET was water limited since differences between reference ET and actual ET were large. ET was largely sensitive to vapour pressure deficit and surface conductance than to net radiation, indicating that the canopies were strongly coupled with the boundary layer. Rangeland ET was successfully simulated and evaporation from the soil was the dominant flux, hence there is scope for reducing the so-called ‘unproductive’ water use. Further, it was shown that the PML was better able to simulate ET compared to the PMP model as revealed by different model evaluation metrics such as the root mean square error, absolute mean square error and the root mean square observations standard deviation ratio. The incorporation of a soil evaporation component in the PMP model improved estimates of ET as revealed by the root mean square error. The results also indicated that both the catchment parameter (w) and the evaporative index were important in highlighting the impacts of land cover change on ET. It was also shown that, despite changes in the local environment such as catchment characteristics, global forces also affected ET at a local scale. Overall, the study demonstrated that combining remote sensing and ground based observations was important to better understand rangeland grass production and water use dynamics.
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- Date Issued: 2018