Modelling dispersal processes in impala-cheetah-lion ecosystems with infection in the lions
- Authors: Mbava, Willard
- Date: 2016
- Subjects: Predation (Biology) -- South Africa -- Kruger National Park Endangered species -- South Africa -- Kruger National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11782 , vital:26968
- Description: The study involved the predator-prey interaction of three species namely the predator (Cheetah Acinonyx jubatus), the super-predator (Lion Panthera leo), and their common prey (Impala Aepyceros melampus). The study area is the Kruger National Park. The predator being an endangered species, faces a survival problem. It is frequently killed by the super-predator to reduce competition for prey. The super-predator also scares away the predator o_ its kills. The prey forms the main diet of the predator. The plight of the predator motivated the author to formulate disease and reaction-diffusion models for the species interactions. The purpose of the models were to predict and explain the effect of large competition from the super-predator on the predator population. Important parameters related to additional predator mortality due to presence of super-predator, the disease incidence rate and induced death rate formed the focal points of the analysis. The dynamics of a predator-prey model with disease in super-predator were investigated. The super-predator species is infected with bovine Tuberculosis. In the study, the disease is considered as biological control to allow the predator population to regain from low numbers. The results highlight that in the absence of additional mortality on the predator by the super-predator, the predator population survives extinction. Furthermore, at current levels of disease incidence, the super-predator population is wiped out by the disease. However, the super-predator population survives extinction if the disease incidence rate is low. Persistence of all populations is possible in the case of low disease incidence rate and no additional mortality imparted on the predator. Furthermore, a two-species subsystem, prey and predator, is considered as a special case to determine the effect of super-predator removal from the system, on the survival of the predator. This is treated as a contrasting case from the smaller parks. The results show that the predator population thrives well in the total absence of its main competitor, with its population rising to at least twice the initial value. A reaction-diffusion three-species predator-prey model was formulated and analysed. Stability of the temporal and the spatio-temporal systems, existence and non-existence of stationary steady state solutions were studied. Conditions for the emergence of stationary patterns were deduced. The results show that by choosing the diffusion coeffcient d2 > _D 2 suffciently large, a non-constant positive solution is generated, that is, stationary patterns emerge, depicting dispersal of species. Predators were observed to occupy habitats surrounding prey. However, super-predators were observed to alternate their habitats, from staying away from prey to invading prey habitat. In the investigation, strategies to determine ways in which the predator species could be saved from extinction and its population improved were devised, and these included isolation of the predator from the super-predator.
- Full Text:
- Date Issued: 2016
- Authors: Mbava, Willard
- Date: 2016
- Subjects: Predation (Biology) -- South Africa -- Kruger National Park Endangered species -- South Africa -- Kruger National Park
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11782 , vital:26968
- Description: The study involved the predator-prey interaction of three species namely the predator (Cheetah Acinonyx jubatus), the super-predator (Lion Panthera leo), and their common prey (Impala Aepyceros melampus). The study area is the Kruger National Park. The predator being an endangered species, faces a survival problem. It is frequently killed by the super-predator to reduce competition for prey. The super-predator also scares away the predator o_ its kills. The prey forms the main diet of the predator. The plight of the predator motivated the author to formulate disease and reaction-diffusion models for the species interactions. The purpose of the models were to predict and explain the effect of large competition from the super-predator on the predator population. Important parameters related to additional predator mortality due to presence of super-predator, the disease incidence rate and induced death rate formed the focal points of the analysis. The dynamics of a predator-prey model with disease in super-predator were investigated. The super-predator species is infected with bovine Tuberculosis. In the study, the disease is considered as biological control to allow the predator population to regain from low numbers. The results highlight that in the absence of additional mortality on the predator by the super-predator, the predator population survives extinction. Furthermore, at current levels of disease incidence, the super-predator population is wiped out by the disease. However, the super-predator population survives extinction if the disease incidence rate is low. Persistence of all populations is possible in the case of low disease incidence rate and no additional mortality imparted on the predator. Furthermore, a two-species subsystem, prey and predator, is considered as a special case to determine the effect of super-predator removal from the system, on the survival of the predator. This is treated as a contrasting case from the smaller parks. The results show that the predator population thrives well in the total absence of its main competitor, with its population rising to at least twice the initial value. A reaction-diffusion three-species predator-prey model was formulated and analysed. Stability of the temporal and the spatio-temporal systems, existence and non-existence of stationary steady state solutions were studied. Conditions for the emergence of stationary patterns were deduced. The results show that by choosing the diffusion coeffcient d2 > _D 2 suffciently large, a non-constant positive solution is generated, that is, stationary patterns emerge, depicting dispersal of species. Predators were observed to occupy habitats surrounding prey. However, super-predators were observed to alternate their habitats, from staying away from prey to invading prey habitat. In the investigation, strategies to determine ways in which the predator species could be saved from extinction and its population improved were devised, and these included isolation of the predator from the super-predator.
- Full Text:
- Date Issued: 2016
Mechanism and synchronicity of wheat (Triticum aestivum) resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1
- Authors: Njom, Henry Akum
- Date: 2016
- Subjects: Wheat -- Disease and pest resistance Bacterial diseases of plants Russian wheat aphid
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2700 , vital:28056
- Description: Wheat (Triticum aestivum and T. Durum) is an extremely important agronomic crop produced worldwide. Wheat consumption has doubled in the last 30 years with approximately 600 million tons consumed per annum. According to the International Maize and Wheat Improvement Center, worldwide wheat demand will increase over 40 percent by 2020, while land as well as resources available for the production will decrease significantly if the current trend prevails. The wheat industry is challenged with abiotic and biotic stressors that lead to reduction in crop yields. Increase knowledge of wheat’s biochemical constitution and functional biology is of paramount importance to improve wheat so as to meet with this demand. Pesticides and fungicides are being used to control biotic stress imposed by insect pest and fungi pathogens but these chemicals pose a risk to the environment and human health. To this effect, there is re-evaluation of pesticides currently in use by the Environmental Protection Agency, via mandates of the 1996 Food Quality Protection Act and those with higher perceived risks are banned. Genetic resistance is now a more environmental friendly and effective method of controlling insect pest and rust diseases of wheat than the costly spraying with pesticides and fungicides. Although, resistant cultivars effectively prevent current prevailing pathotypes of leaf rust and biotypes of Russian wheat aphid from attacking wheat, new pathotypes and biotypes of the pathogen/pest may develop and infect resistant cultivars. Therefore, breeders are continually searching for new sources of resistance. Proteomic approaches can be utilised to ascertain target enzymes and proteins from resistant lines that could be utilised to augment the natural tolerance of agronomically favourable varieties of wheat. With this ultimate goal in mind, the aim of this study was to elucidate the mechanism and synchronicity of wheat resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1. To determine the resistance mechanism of the wheat cultivars to leaf rust infection and Russian wheat aphid infestation, a proteomics approach using two-dimensional gel electrophoresis was used in order to determine the effect of RWA SA1 on the wheat cultivars proteome. Differentially expressed proteins that were up or down regulated (appearing or disappearing) were identified using PDQuestTM Basic 2-DE Gel analysis software. Proteins bands of interest were in-gel trypsin digested as per the protocol described in Schevchenko et al. (2007) and analysed using a Dionex Ultimate 3000 RSLC system coupled to an AB Sciex 6600 TripleTOF mass spectrometer. Protein pilot v5 using Paragon search engine (AB Sciex) was used for comparison of the obtained MS/MS spectra with a custom database containing sequences of Puccinia triticina (Uniprot Swissprot), Triticum aestivum (Uniprot TrEMBL) and Russian wheat aphid (Uniprot TrEMBL) as well as a list of sequences from common contaminating proteins. Proteins with a threshold of ≥99.9 percent confidence were reported. A total of 72 proteins were putatively identified from the 37 protein spots excised originating from either leaf rust or Russian wheat aphid experiments. Sixty-three of these proteins were associated with wheat response to stress imposed by RWA SA1 feeding while 39 were associated with infection by Puccinia triticina. Several enzymes involved in the Calvin cycle, electron transport and ATP synthesis were observed to be differentially regulated suggesting greater metabolic requirements in the wheat plants following aphid infestation and leaf rust infection. Proteins directly associated with photosynthesis were also differentially regulated following RWA SA1 infestation and P.
- Full Text:
- Date Issued: 2016
- Authors: Njom, Henry Akum
- Date: 2016
- Subjects: Wheat -- Disease and pest resistance Bacterial diseases of plants Russian wheat aphid
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2700 , vital:28056
- Description: Wheat (Triticum aestivum and T. Durum) is an extremely important agronomic crop produced worldwide. Wheat consumption has doubled in the last 30 years with approximately 600 million tons consumed per annum. According to the International Maize and Wheat Improvement Center, worldwide wheat demand will increase over 40 percent by 2020, while land as well as resources available for the production will decrease significantly if the current trend prevails. The wheat industry is challenged with abiotic and biotic stressors that lead to reduction in crop yields. Increase knowledge of wheat’s biochemical constitution and functional biology is of paramount importance to improve wheat so as to meet with this demand. Pesticides and fungicides are being used to control biotic stress imposed by insect pest and fungi pathogens but these chemicals pose a risk to the environment and human health. To this effect, there is re-evaluation of pesticides currently in use by the Environmental Protection Agency, via mandates of the 1996 Food Quality Protection Act and those with higher perceived risks are banned. Genetic resistance is now a more environmental friendly and effective method of controlling insect pest and rust diseases of wheat than the costly spraying with pesticides and fungicides. Although, resistant cultivars effectively prevent current prevailing pathotypes of leaf rust and biotypes of Russian wheat aphid from attacking wheat, new pathotypes and biotypes of the pathogen/pest may develop and infect resistant cultivars. Therefore, breeders are continually searching for new sources of resistance. Proteomic approaches can be utilised to ascertain target enzymes and proteins from resistant lines that could be utilised to augment the natural tolerance of agronomically favourable varieties of wheat. With this ultimate goal in mind, the aim of this study was to elucidate the mechanism and synchronicity of wheat resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1. To determine the resistance mechanism of the wheat cultivars to leaf rust infection and Russian wheat aphid infestation, a proteomics approach using two-dimensional gel electrophoresis was used in order to determine the effect of RWA SA1 on the wheat cultivars proteome. Differentially expressed proteins that were up or down regulated (appearing or disappearing) were identified using PDQuestTM Basic 2-DE Gel analysis software. Proteins bands of interest were in-gel trypsin digested as per the protocol described in Schevchenko et al. (2007) and analysed using a Dionex Ultimate 3000 RSLC system coupled to an AB Sciex 6600 TripleTOF mass spectrometer. Protein pilot v5 using Paragon search engine (AB Sciex) was used for comparison of the obtained MS/MS spectra with a custom database containing sequences of Puccinia triticina (Uniprot Swissprot), Triticum aestivum (Uniprot TrEMBL) and Russian wheat aphid (Uniprot TrEMBL) as well as a list of sequences from common contaminating proteins. Proteins with a threshold of ≥99.9 percent confidence were reported. A total of 72 proteins were putatively identified from the 37 protein spots excised originating from either leaf rust or Russian wheat aphid experiments. Sixty-three of these proteins were associated with wheat response to stress imposed by RWA SA1 feeding while 39 were associated with infection by Puccinia triticina. Several enzymes involved in the Calvin cycle, electron transport and ATP synthesis were observed to be differentially regulated suggesting greater metabolic requirements in the wheat plants following aphid infestation and leaf rust infection. Proteins directly associated with photosynthesis were also differentially regulated following RWA SA1 infestation and P.
- Full Text:
- Date Issued: 2016
Measuring the performance of the banking sector in Zimbabwe
- Authors: Abel, Sanderson
- Date: 2016
- Subjects: Banks and banking -- Zimbabwe , Bank profits -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5110 , vital:20806
- Description: The measurement of the banking sector performance in Zimbabwe is motivated by the unique developments that typified the sector during the period 2009-2014 after emerging from an economic crisis. The Zimbabwean economy returned to stability and growth in 2009, after a decade long economic decline. Economic stability brought about growth in deposits, loans, assets, capitalization and profits during this period. The banking sector has been accused of excessive profiteering through overpricing their products, which culminated in the intervention by the authorities in the sector. The interest rates spread, fees and other charges were presumed to be high which motivated the need to understand whether the banking sector is efficient or inefficient given the high interest rate spreads between the deposit rates and lending rates. Furthermore the high interest rates have raised the question of whether banks were exploiting their market power to price their products highly or whether their prices were determined by the dictates of market forces. Continued profitability of the sector also called for an investigation into what was driving the persistence of profitability over time. The primary objective of this research was to measure the performance of the banking sector during the period 2009-2014. The study contributes to the empirical literature by measuring and assessing the drivers of banking sector competition, efficiency and profitability and applying them at much disaggregated levels. This study also contributes to the debate on the relationships among the performance measures of competition, profitability and efficiency. The study adopted a number of methods which contributes to the array of tools central banks can employ to measure bank performance. The study employed a number of methodologies to measure the competition, efficiency and profitability performance of the banking sector. Competition was estimated using the new empirical industrial organisation methods of Panza and Rose (1987) and the Lerner (1934) Index was used. Cost and revenue efficiency was estimated using the two step methods of Data Envelopment Analysis followed by the Tobit regression method. An assessment of the persistence and drivers of profitability was measured using the Generalised Method of Moments. This study shows that the banking sector was operating under monopolistic competition market structure. This implies that banks held some market power as a result of product differentiation due to unique features such as brands, image and advertising, among others. The study indicates that competition increased during the period 2009-2014. Market power/competition in the banking sector during the study period was driven by capital adequacy, non-performing loans, liquidity risk, cost-income ratio, economic growth and government policy on pricing of bank products. The study suggests that the banking sector experienced an average inefficiency level of approximately 35 per cent in relationship with the best performing institutions in the sample. As a result of stability experienced in the economy, the average revenue and cost efficiency increased between 2009 and 2014. The study further established that the discord around the implementation of the indigenisation and empowerment law, coupled with the government intervention in the banking sector had a negative impact on the banking sector efficiency. It also found that efficiency is determined by market power, capital adequacy, cost income ratio, economic growth, inflation, market share and profitability. The Granger Causality test between cost efficiency and market power suggests that causality is bidirectional. On the other hand granger causality between revenue efficiency and market power is unidirectional and positive, running from revenue efficiency to market power. The result implies that policy measures should bring a balance between increasing competition and improving the revenue efficiency. The study shows that the banking sector was profitable during the period 2009 to 2014. The profitability was a reflection of a stable macroeconomic environment, typified by low inflation levels, despite the crises during this period. It further reveals that the banking sector‟s profitability persisted over time, reflecting the regulatory structure of the sector. The study established that profitability was determined by market power, non-performing loans, liquidity risk, capital adequacy, bank size and cost efficiency. This implies profitability was driven by bank specific determinants. There are a number of policy implications derived from the study. Regulatory measures such as forced consolidations can lead to excessive market power by the banking institution; hence it should be moderated. Banks should enhance credit risk because NPLs has been dragging profits. Banks should take advantage of the various measures introduced, such as the setting up of the special purpose vehicle and credit reference bureau. The government should avoid tampering with market forces as this reduces competition, efficiency and profitability and put in place measures that grow the economy as it increases the efficiency and profitability of the banking sector.
- Full Text:
- Date Issued: 2016
- Authors: Abel, Sanderson
- Date: 2016
- Subjects: Banks and banking -- Zimbabwe , Bank profits -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5110 , vital:20806
- Description: The measurement of the banking sector performance in Zimbabwe is motivated by the unique developments that typified the sector during the period 2009-2014 after emerging from an economic crisis. The Zimbabwean economy returned to stability and growth in 2009, after a decade long economic decline. Economic stability brought about growth in deposits, loans, assets, capitalization and profits during this period. The banking sector has been accused of excessive profiteering through overpricing their products, which culminated in the intervention by the authorities in the sector. The interest rates spread, fees and other charges were presumed to be high which motivated the need to understand whether the banking sector is efficient or inefficient given the high interest rate spreads between the deposit rates and lending rates. Furthermore the high interest rates have raised the question of whether banks were exploiting their market power to price their products highly or whether their prices were determined by the dictates of market forces. Continued profitability of the sector also called for an investigation into what was driving the persistence of profitability over time. The primary objective of this research was to measure the performance of the banking sector during the period 2009-2014. The study contributes to the empirical literature by measuring and assessing the drivers of banking sector competition, efficiency and profitability and applying them at much disaggregated levels. This study also contributes to the debate on the relationships among the performance measures of competition, profitability and efficiency. The study adopted a number of methods which contributes to the array of tools central banks can employ to measure bank performance. The study employed a number of methodologies to measure the competition, efficiency and profitability performance of the banking sector. Competition was estimated using the new empirical industrial organisation methods of Panza and Rose (1987) and the Lerner (1934) Index was used. Cost and revenue efficiency was estimated using the two step methods of Data Envelopment Analysis followed by the Tobit regression method. An assessment of the persistence and drivers of profitability was measured using the Generalised Method of Moments. This study shows that the banking sector was operating under monopolistic competition market structure. This implies that banks held some market power as a result of product differentiation due to unique features such as brands, image and advertising, among others. The study indicates that competition increased during the period 2009-2014. Market power/competition in the banking sector during the study period was driven by capital adequacy, non-performing loans, liquidity risk, cost-income ratio, economic growth and government policy on pricing of bank products. The study suggests that the banking sector experienced an average inefficiency level of approximately 35 per cent in relationship with the best performing institutions in the sample. As a result of stability experienced in the economy, the average revenue and cost efficiency increased between 2009 and 2014. The study further established that the discord around the implementation of the indigenisation and empowerment law, coupled with the government intervention in the banking sector had a negative impact on the banking sector efficiency. It also found that efficiency is determined by market power, capital adequacy, cost income ratio, economic growth, inflation, market share and profitability. The Granger Causality test between cost efficiency and market power suggests that causality is bidirectional. On the other hand granger causality between revenue efficiency and market power is unidirectional and positive, running from revenue efficiency to market power. The result implies that policy measures should bring a balance between increasing competition and improving the revenue efficiency. The study shows that the banking sector was profitable during the period 2009 to 2014. The profitability was a reflection of a stable macroeconomic environment, typified by low inflation levels, despite the crises during this period. It further reveals that the banking sector‟s profitability persisted over time, reflecting the regulatory structure of the sector. The study established that profitability was determined by market power, non-performing loans, liquidity risk, capital adequacy, bank size and cost efficiency. This implies profitability was driven by bank specific determinants. There are a number of policy implications derived from the study. Regulatory measures such as forced consolidations can lead to excessive market power by the banking institution; hence it should be moderated. Banks should enhance credit risk because NPLs has been dragging profits. Banks should take advantage of the various measures introduced, such as the setting up of the special purpose vehicle and credit reference bureau. The government should avoid tampering with market forces as this reduces competition, efficiency and profitability and put in place measures that grow the economy as it increases the efficiency and profitability of the banking sector.
- Full Text:
- Date Issued: 2016
Managing change in organisational environment
- Authors: Markova, Elena
- Date: 2016
- Subjects: Organizational change , Conflict management , Teams in the workplace
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8129 , vital:25017
- Description: Twentieth century has set an unprecedented pace of change, which seems to be ever increasing. The changes are transforming every sphere of social life including business and organisational life. Globalisation has made organisational structures flatter but wider in reach. Advancements in information and communication technologies have made teams larger through vast and powerful information networks. These forces are triggering the reshaping and restructuring of every major industry worldwide nowadays. The main research aim of this study is to explore how organisational conflict is affected by change (and vice versa) in order to work out a set of recommendations which shall take form of practical intervention strategies for the improvement of organizational effectiveness by mitigating the dysfunctions of a conflict and adjusting employees' styles of handling interpersonal and intergroup conflict. Workplace conflict is an everyday reality. It is an inevitable result of human interaction in a competitive environment of the workplace. So, according to this assumption, conflict is not something vicious and destructive, but an intrinsic part of human interaction. Then, the conflict is not a problem in itself, the way it is managed is what defines whether the conflict is destructive or not.
- Full Text:
- Date Issued: 2016
- Authors: Markova, Elena
- Date: 2016
- Subjects: Organizational change , Conflict management , Teams in the workplace
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8129 , vital:25017
- Description: Twentieth century has set an unprecedented pace of change, which seems to be ever increasing. The changes are transforming every sphere of social life including business and organisational life. Globalisation has made organisational structures flatter but wider in reach. Advancements in information and communication technologies have made teams larger through vast and powerful information networks. These forces are triggering the reshaping and restructuring of every major industry worldwide nowadays. The main research aim of this study is to explore how organisational conflict is affected by change (and vice versa) in order to work out a set of recommendations which shall take form of practical intervention strategies for the improvement of organizational effectiveness by mitigating the dysfunctions of a conflict and adjusting employees' styles of handling interpersonal and intergroup conflict. Workplace conflict is an everyday reality. It is an inevitable result of human interaction in a competitive environment of the workplace. So, according to this assumption, conflict is not something vicious and destructive, but an intrinsic part of human interaction. Then, the conflict is not a problem in itself, the way it is managed is what defines whether the conflict is destructive or not.
- Full Text:
- Date Issued: 2016
Links between valley confinement, landforms and vegetation distribution in a semi-arid valley floor environment, Baviaanskloof, South Africa
- Authors: Smith-Adao, Lindie B
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/953 , vital:20006
- Description: Although a large body of international literature has advanced our understanding of river systems, a considerable amount of gaps exit in the knowledge of dryland systems. River systems reflect complex interactions between biophysical processes and patterns. Understanding how processes generate observed patterns and, in turn, how patterns influence processes is crucial to understanding river structure and function. It requires an interdisciplinary approach in both research and resulting applications. The aim of this thesis was to examine the relationship between valley confinement, fluvial style, valley floor morphology and vegetation in the semi-arid environment of the Baviaanskloof river catchment, South Africa. This interdisciplinary investigation used a mixed method approach that involved desktop analyses and field surveys to understand dynamics at multiple scales, from the whole catchment to local (site, reach and quadrat or sample plot) scales. The desktop analyses included historical rainfall patterns and climate extremes, aerial photograph time-series and remote sensing greenness indices, and the field surveys focussed on cross-valley landform profiles, groundwater depth levels, sediment size distribution and soil chemistry, and vegetation distribution patterns. Based on the integrative assessment of these techniques a framework was developed of the links between valley confinement, surface-groundwater interaction, hydrogeomorphic processes and landforms, vegetation and human activities. Study findings highlighted the fact that very strong links exist between these factors. In this semi-arid area water availability (groundwater and streamflow conditions) was the primary control on valley floor vegetation composition and patterning. One group of species was associated with the wetted channel reaches at confined and semi-confined valley settings, while the other was associated with dry bed channel reaches at unconfined valley settings. The analyses also indicated that the environmental variables which best explained the variation in vegetation at the differing geomorphic landforms were related to landform position (elevation and distance), sediment size (fine and coarse sand) and available phosphorus (i.e. human impacts). The different plants, in turn, also affected landforms through their influence on sediment erosion, transport and deposition. Specially, they build, maintained or modified geomorphic landforms at confined, semi-confined and unconfined valley settings across the valley floor. Valley confinement was a primary control influencing hydrogeomorphic processes and their associated landforms. Alluvial fans and terraces acted as critical additional controls at especially the unconfined valley setting. Implications for restoration efforts in the catchment included strategies that took cognisance of: active revegetation on floodplain surfaces related to former agricultural fields; channel switching associated with the highly dynamic and unpredictable nature of geomorphic features; unstable multi-thread braided channels in the unconfined valley setting; and the selection of representative monitoring sites.
- Full Text:
- Date Issued: 2016
- Authors: Smith-Adao, Lindie B
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/953 , vital:20006
- Description: Although a large body of international literature has advanced our understanding of river systems, a considerable amount of gaps exit in the knowledge of dryland systems. River systems reflect complex interactions between biophysical processes and patterns. Understanding how processes generate observed patterns and, in turn, how patterns influence processes is crucial to understanding river structure and function. It requires an interdisciplinary approach in both research and resulting applications. The aim of this thesis was to examine the relationship between valley confinement, fluvial style, valley floor morphology and vegetation in the semi-arid environment of the Baviaanskloof river catchment, South Africa. This interdisciplinary investigation used a mixed method approach that involved desktop analyses and field surveys to understand dynamics at multiple scales, from the whole catchment to local (site, reach and quadrat or sample plot) scales. The desktop analyses included historical rainfall patterns and climate extremes, aerial photograph time-series and remote sensing greenness indices, and the field surveys focussed on cross-valley landform profiles, groundwater depth levels, sediment size distribution and soil chemistry, and vegetation distribution patterns. Based on the integrative assessment of these techniques a framework was developed of the links between valley confinement, surface-groundwater interaction, hydrogeomorphic processes and landforms, vegetation and human activities. Study findings highlighted the fact that very strong links exist between these factors. In this semi-arid area water availability (groundwater and streamflow conditions) was the primary control on valley floor vegetation composition and patterning. One group of species was associated with the wetted channel reaches at confined and semi-confined valley settings, while the other was associated with dry bed channel reaches at unconfined valley settings. The analyses also indicated that the environmental variables which best explained the variation in vegetation at the differing geomorphic landforms were related to landform position (elevation and distance), sediment size (fine and coarse sand) and available phosphorus (i.e. human impacts). The different plants, in turn, also affected landforms through their influence on sediment erosion, transport and deposition. Specially, they build, maintained or modified geomorphic landforms at confined, semi-confined and unconfined valley settings across the valley floor. Valley confinement was a primary control influencing hydrogeomorphic processes and their associated landforms. Alluvial fans and terraces acted as critical additional controls at especially the unconfined valley setting. Implications for restoration efforts in the catchment included strategies that took cognisance of: active revegetation on floodplain surfaces related to former agricultural fields; channel switching associated with the highly dynamic and unpredictable nature of geomorphic features; unstable multi-thread braided channels in the unconfined valley setting; and the selection of representative monitoring sites.
- Full Text:
- Date Issued: 2016
Life history of the maritime platygastrid Echthrodesis lamorali Masner 1968 (Hymenoptera: Platygastridae: Scelioninae)
- Authors: Owen, Candice Ann
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/837 , vital:19995 , 10.21504/10962/837
- Description: Echthrodesis lamorali Masner 1968 (Hymenoptera: Platygastridae, Scelioninae) is an intertidal parasitoid wasp that uses the eggs of the maritime spider, Desis formidabilis O.P. Cambridge 1890 (Araneae: Desidae), as a host. This species is one of only three known maritime parasitoids globally, and is the only known spider egg parasitoid that attacks its host within the intertidal region in southern Africa. Originally described from ‘The Island’, Kommetjie (Western Cape, South Africa), this shore was the only known locality of the species at the commencement of this thesis. Furthermore, the extent of the parasitism pressure the wasp exerts on D. formidabilis was largely unknown, along with its basic biology (drivers of its broad-scale and fine-scale distribution patterns; parasitism incidence; and sex ratios) and morphological and physiological adaptations for living within the frequently saltwater-inundated environment. This thesis unravelled these aspects, as well as experimentally provided data for many components of the life history of E. lamorali that had only been hypothesized by other authors, at a variety of scales, from the country-wide ecosystem, to single shores, and finally to the scale of the individual. While the distribution of E. lamorali was found to be much wider than previously thought, it remained restricted to the shores of the Cape Peninsula (Western Cape, South Africa). The host spiders were located throughout a much wider distributional range than the wasp, from East London in the east to the Peninsula, but some behavioural and morphological differences were found between those within and outside of the range of the parasitoid, suggesting range-limitation imposed by the host on E. lamorali. This limitation may be strengthened by the general lack of suitable shore types within the close vicinity of the Peninsula. Modelling using macro-climatic conditions suggested that maximum temperatures and humidities were also largely limiting to E. lamorali, although these patterns were not observable in the micro-climates in which the species survives. The wasp populations and spiders within the range of E. lamorali as identified in Chapter 2 were assessed to determine any preferences for local conditions, including location along the Peninsula, nesting sites and intertidal zones within single shores, using AICc modelling, which detected parasitism patterns in D. formidabilis and E. lamorali populations, as well as the sex ratios in the latter species. The models showed that the spider population size and distribution was more influenced by bottom-up factors such as abiotic components of the shore than by parasitism, which only showed density dependence with the host at certain scales. Both host and parasitoid populations illustrated a preference for the middle zone on single shores. Observed spider nest characteristics suggested opportunistic nesting behaviour in the species, although preference was shown for construction along an east-west orientation and in locations with low sun exposure. Along with larger population sizes on the west coast over the east coast (not reflected by E. lamorali), these observations suggest that D. formidabilis prefers cooler environments. Spider brood success was 50% in unparasitized egg-sacs, but this figure halved when E. lamorali gained access to the eggs (of which 100% within a single compartment were parasitized each time). Encapsulation of the embryo was found to be positively correlated with parasitism, indicating some form of host resistance. Resultant parasitoid broods illustrated a strong female bias in the species, as is common for this group of insects. The life history of E. lamorali was then assessed at a smaller scale, that of the individual. Scanning electron microscopy of whole E. lamorali specimens and light microscopy of sectioned specimens demonstrated no morphological adaptations in the trachea and spiracles to cope with saltwater inundation. On the other hand, respirometry experiments categorically demonstrated that the species copes with inundation through the formation of a physical gill over the full habitus, and the induction of a state of torpor to reduce metabolic needs, when submerged. This precludes the need for any further morphological adaptations. Determination of the wasp’s critical thermal tolerance illustrated a wide temperature range with a particularly cold lower limit of -1.1ºC ± 0.16, suggesting the presence of related genera or ancestors in much colder environments. With a much broader distribution than previously thought, and the inclusion of the distributional range of E. lamorali within the Table Mountain National Park, this species is being effectively conserved and managed through the umbrella-conservation of the park. Links to the host proved to vary at differing scales, proving the need for scale considerations to be included in other similar biological and ecological studies. Finally, the species showed physiological adaptation to its intertidal existence. Echthrodesis lamorali, the only discovered maritime spider egg parasitoid in Southern Africa, displayed unusual characteristics at every scale of its life history and as such, warrants further investigation.
- Full Text:
- Date Issued: 2016
- Authors: Owen, Candice Ann
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/837 , vital:19995 , 10.21504/10962/837
- Description: Echthrodesis lamorali Masner 1968 (Hymenoptera: Platygastridae, Scelioninae) is an intertidal parasitoid wasp that uses the eggs of the maritime spider, Desis formidabilis O.P. Cambridge 1890 (Araneae: Desidae), as a host. This species is one of only three known maritime parasitoids globally, and is the only known spider egg parasitoid that attacks its host within the intertidal region in southern Africa. Originally described from ‘The Island’, Kommetjie (Western Cape, South Africa), this shore was the only known locality of the species at the commencement of this thesis. Furthermore, the extent of the parasitism pressure the wasp exerts on D. formidabilis was largely unknown, along with its basic biology (drivers of its broad-scale and fine-scale distribution patterns; parasitism incidence; and sex ratios) and morphological and physiological adaptations for living within the frequently saltwater-inundated environment. This thesis unravelled these aspects, as well as experimentally provided data for many components of the life history of E. lamorali that had only been hypothesized by other authors, at a variety of scales, from the country-wide ecosystem, to single shores, and finally to the scale of the individual. While the distribution of E. lamorali was found to be much wider than previously thought, it remained restricted to the shores of the Cape Peninsula (Western Cape, South Africa). The host spiders were located throughout a much wider distributional range than the wasp, from East London in the east to the Peninsula, but some behavioural and morphological differences were found between those within and outside of the range of the parasitoid, suggesting range-limitation imposed by the host on E. lamorali. This limitation may be strengthened by the general lack of suitable shore types within the close vicinity of the Peninsula. Modelling using macro-climatic conditions suggested that maximum temperatures and humidities were also largely limiting to E. lamorali, although these patterns were not observable in the micro-climates in which the species survives. The wasp populations and spiders within the range of E. lamorali as identified in Chapter 2 were assessed to determine any preferences for local conditions, including location along the Peninsula, nesting sites and intertidal zones within single shores, using AICc modelling, which detected parasitism patterns in D. formidabilis and E. lamorali populations, as well as the sex ratios in the latter species. The models showed that the spider population size and distribution was more influenced by bottom-up factors such as abiotic components of the shore than by parasitism, which only showed density dependence with the host at certain scales. Both host and parasitoid populations illustrated a preference for the middle zone on single shores. Observed spider nest characteristics suggested opportunistic nesting behaviour in the species, although preference was shown for construction along an east-west orientation and in locations with low sun exposure. Along with larger population sizes on the west coast over the east coast (not reflected by E. lamorali), these observations suggest that D. formidabilis prefers cooler environments. Spider brood success was 50% in unparasitized egg-sacs, but this figure halved when E. lamorali gained access to the eggs (of which 100% within a single compartment were parasitized each time). Encapsulation of the embryo was found to be positively correlated with parasitism, indicating some form of host resistance. Resultant parasitoid broods illustrated a strong female bias in the species, as is common for this group of insects. The life history of E. lamorali was then assessed at a smaller scale, that of the individual. Scanning electron microscopy of whole E. lamorali specimens and light microscopy of sectioned specimens demonstrated no morphological adaptations in the trachea and spiracles to cope with saltwater inundation. On the other hand, respirometry experiments categorically demonstrated that the species copes with inundation through the formation of a physical gill over the full habitus, and the induction of a state of torpor to reduce metabolic needs, when submerged. This precludes the need for any further morphological adaptations. Determination of the wasp’s critical thermal tolerance illustrated a wide temperature range with a particularly cold lower limit of -1.1ºC ± 0.16, suggesting the presence of related genera or ancestors in much colder environments. With a much broader distribution than previously thought, and the inclusion of the distributional range of E. lamorali within the Table Mountain National Park, this species is being effectively conserved and managed through the umbrella-conservation of the park. Links to the host proved to vary at differing scales, proving the need for scale considerations to be included in other similar biological and ecological studies. Finally, the species showed physiological adaptation to its intertidal existence. Echthrodesis lamorali, the only discovered maritime spider egg parasitoid in Southern Africa, displayed unusual characteristics at every scale of its life history and as such, warrants further investigation.
- Full Text:
- Date Issued: 2016
Leonotis leonurus: understanding the mechanism of anti-diabetic action and investigating a nano drug delivery system
- Odei-Addo, Frank, Levendal, Ruby-Ann
- Authors: Odei-Addo, Frank , Levendal, Ruby-Ann
- Date: 2016
- Subjects: Diabetes Plant extracts
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/13116 , vital:27153
- Description: Diabetes mellitus is a metabolic disease characterised by hyperglycaemia resulting from defects in insulin secretion, insulin action, or both. The leaf extract of Leonotis leonurus and its active compound marrubiin, have been shown to possess anti-diabetic, antiplatelet, anti-inflammatory and anti-coagulation activity. In the present study, the mechanism by which L. leonurus and marrubiin exert their anti-diabetic properties, the cross-talk between the peripheral tissues and a nano drug delivery system were investigated. Marrubiin in the plant extract was effectively quantified by an optimised reversed phase highperformance liquid chromatography (HPLC) protocol using a pentafluorophenyl (PFP) column with water and acetonitrile (50:50) as mobile phase, and a flow rate of 1ml/min. The chemical structure was determined using liquid chromatography-tandem mass spectroscopy LC-MS/MS. Real-time quantitative polymerase chain reaction (RT-qPCR) gene expression of selected adipokines and proteins implicated in Type-2 diabetes (T2D) were investigated in specific peripheral tissues isolated from an in vivo obese rat model. An in vitro cell culture model was used to determine the crosstalk between the peripheral tissues and pancreatic (INS-1E) β-cells. Various nanoformulations of L. leonurus extract were prepared and their effect on cytotoxicity (in Chang liver and INS-1 cells), insulin-mediated glucose uptake (Change liver cells) and insulin secretion (INS-1) were investigated. The average yield of marrubiin from the plant extract was 10% (n=3), with a molecular mass of 333.20Da and a molecular formula of C20H29O4 +. Results from the in vivo study showed that the L. leonurus extract significantly (p<0.05) enhanced the gene expression of adiponectin, peroxisome proliferator-activated receptor gamma (PPAR-γ), glucokinase (GK), uncoupling protein-2 (UCP-2) and reduced leptin in adipose tissue, but resistin, glucose transporters (GLUT), fatty acid synthase (FAS), insulin receptor substrate -1 (IRS-1) and phosphoenolpyruvate carboxykinase (PEPCK) gene expression were not affected. Marrubiin decreased gene expression of leptin and resistin, and increased IRS-1 and glucokinase in adipose tissue. In liver and muscle tissues, marrubiin and the L. leonurus extract reduced gene expression of PPAR-γ, IRS-1, glucokinase and PEPCK. In the in vitro crosstalk study (under normoglycaemic and hyperglycaemic conditions), conditioned medium from 3T3-L1 cells significantly (p<0.01) enhanced insulin secretion. This was not observed in INS-1E cells exposed to muscle- and liver-conditioned medium, respectively. The in vitro studies using a nanostructured lipid formulation (NLC) of the plant extract was not cytotoxic to either INS-1 and Chang liver cells. The NLC formulation significantly (p<0.05) enhanced glucose uptake in Chang liver cells and improved chronic insulin release in INS-1 cells (p<0.05). Based on the above findings from the in vivo and in vitro studies, both L. leonurus and marrubiin exerted an insulinotropic effect via adipose tissue on pancreatic β-cells. The findings in the in vivo study showed that marrubiin and the L. leonurus extract were employing their major anti-diabetic action via the adipose tissue.
- Full Text:
- Date Issued: 2016
- Authors: Odei-Addo, Frank , Levendal, Ruby-Ann
- Date: 2016
- Subjects: Diabetes Plant extracts
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/13116 , vital:27153
- Description: Diabetes mellitus is a metabolic disease characterised by hyperglycaemia resulting from defects in insulin secretion, insulin action, or both. The leaf extract of Leonotis leonurus and its active compound marrubiin, have been shown to possess anti-diabetic, antiplatelet, anti-inflammatory and anti-coagulation activity. In the present study, the mechanism by which L. leonurus and marrubiin exert their anti-diabetic properties, the cross-talk between the peripheral tissues and a nano drug delivery system were investigated. Marrubiin in the plant extract was effectively quantified by an optimised reversed phase highperformance liquid chromatography (HPLC) protocol using a pentafluorophenyl (PFP) column with water and acetonitrile (50:50) as mobile phase, and a flow rate of 1ml/min. The chemical structure was determined using liquid chromatography-tandem mass spectroscopy LC-MS/MS. Real-time quantitative polymerase chain reaction (RT-qPCR) gene expression of selected adipokines and proteins implicated in Type-2 diabetes (T2D) were investigated in specific peripheral tissues isolated from an in vivo obese rat model. An in vitro cell culture model was used to determine the crosstalk between the peripheral tissues and pancreatic (INS-1E) β-cells. Various nanoformulations of L. leonurus extract were prepared and their effect on cytotoxicity (in Chang liver and INS-1 cells), insulin-mediated glucose uptake (Change liver cells) and insulin secretion (INS-1) were investigated. The average yield of marrubiin from the plant extract was 10% (n=3), with a molecular mass of 333.20Da and a molecular formula of C20H29O4 +. Results from the in vivo study showed that the L. leonurus extract significantly (p<0.05) enhanced the gene expression of adiponectin, peroxisome proliferator-activated receptor gamma (PPAR-γ), glucokinase (GK), uncoupling protein-2 (UCP-2) and reduced leptin in adipose tissue, but resistin, glucose transporters (GLUT), fatty acid synthase (FAS), insulin receptor substrate -1 (IRS-1) and phosphoenolpyruvate carboxykinase (PEPCK) gene expression were not affected. Marrubiin decreased gene expression of leptin and resistin, and increased IRS-1 and glucokinase in adipose tissue. In liver and muscle tissues, marrubiin and the L. leonurus extract reduced gene expression of PPAR-γ, IRS-1, glucokinase and PEPCK. In the in vitro crosstalk study (under normoglycaemic and hyperglycaemic conditions), conditioned medium from 3T3-L1 cells significantly (p<0.01) enhanced insulin secretion. This was not observed in INS-1E cells exposed to muscle- and liver-conditioned medium, respectively. The in vitro studies using a nanostructured lipid formulation (NLC) of the plant extract was not cytotoxic to either INS-1 and Chang liver cells. The NLC formulation significantly (p<0.05) enhanced glucose uptake in Chang liver cells and improved chronic insulin release in INS-1 cells (p<0.05). Based on the above findings from the in vivo and in vitro studies, both L. leonurus and marrubiin exerted an insulinotropic effect via adipose tissue on pancreatic β-cells. The findings in the in vivo study showed that marrubiin and the L. leonurus extract were employing their major anti-diabetic action via the adipose tissue.
- Full Text:
- Date Issued: 2016
Land-use effects on mammal communities in the Fish-Kowie corridor, Eastern Cape, South Africa, with particular reference to carnivores
- Authors: Kok, Armand du Preez
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/561 , vital:19970
- Description: Human population growth is causing an increase in habitat transformation on a global scale, and this transformation is driven by changes in land-use practices. One consequence of habitat transformation is the negative effect it can have on mammal communities, especially carnivores. Carnivores are important components of ecosystems as they play an essential structuring role, but also often come into conflict with people. I studied the impact of land-use on mammalian diversity, the attitudes of landowners/managers towards carnivores, the distribution of carnivores, and the interactions among carnivore species in the Fish-Kowie corridor (FKC), an area of conservation concern, in the Eastern Cape, South Africa. Livestock and game farming are the two dominant land-use types in the FKC. Carnivore distribution data were collected between 2012 and 2014 using a robust camera trap survey that consisted of 432 camera stations (216 on livestock and 216 on game farms). In addition, the attitudes of 55 landowners/managers were assessed using semi- structured questionnaire interviews that were conducted in person. My results revealed that mammal diversity was similar on the two land-use types. However, individual species differed in their distribution on the two land-use types. In general, both livestock and game farmers had negative attitudes towards carnivores in the FKC, due to their depredation of valuable livestock and game species. Black-backed jackals (Canis mesomelas), caracals (Caracal caracal), leopards (Panthera pardus), and brown hyaenas (Parahyaena brunnea) were considered the most problematic carnivores, but sensitivity to land-use varied among these four species. Black- backed jackals had the highest occupancy rates of all four predators and were 3.8 times more likely to occupy sites on game farms compared to livestock farms. By contrast, leopards and brown hyaenas were only detected on game farms, and caracals did not appear to be sensitive to the effects of land-use. In general, the interactions among carnivores were weak and were likely driven by carnivore diversity, resource partitioning, and anthropogenic pressures. While there were many subtle differences in the distribution of mammal species and human attitudes towards wildlife on livestock and game farms in the FKC, there were also many similarities. My study has produced results that can be used by the FKC community to better understand how mammals and humans interact across the landscape, information that will ultimately contribute to future conservation planning in the area.
- Full Text:
- Date Issued: 2016
- Authors: Kok, Armand du Preez
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/561 , vital:19970
- Description: Human population growth is causing an increase in habitat transformation on a global scale, and this transformation is driven by changes in land-use practices. One consequence of habitat transformation is the negative effect it can have on mammal communities, especially carnivores. Carnivores are important components of ecosystems as they play an essential structuring role, but also often come into conflict with people. I studied the impact of land-use on mammalian diversity, the attitudes of landowners/managers towards carnivores, the distribution of carnivores, and the interactions among carnivore species in the Fish-Kowie corridor (FKC), an area of conservation concern, in the Eastern Cape, South Africa. Livestock and game farming are the two dominant land-use types in the FKC. Carnivore distribution data were collected between 2012 and 2014 using a robust camera trap survey that consisted of 432 camera stations (216 on livestock and 216 on game farms). In addition, the attitudes of 55 landowners/managers were assessed using semi- structured questionnaire interviews that were conducted in person. My results revealed that mammal diversity was similar on the two land-use types. However, individual species differed in their distribution on the two land-use types. In general, both livestock and game farmers had negative attitudes towards carnivores in the FKC, due to their depredation of valuable livestock and game species. Black-backed jackals (Canis mesomelas), caracals (Caracal caracal), leopards (Panthera pardus), and brown hyaenas (Parahyaena brunnea) were considered the most problematic carnivores, but sensitivity to land-use varied among these four species. Black- backed jackals had the highest occupancy rates of all four predators and were 3.8 times more likely to occupy sites on game farms compared to livestock farms. By contrast, leopards and brown hyaenas were only detected on game farms, and caracals did not appear to be sensitive to the effects of land-use. In general, the interactions among carnivores were weak and were likely driven by carnivore diversity, resource partitioning, and anthropogenic pressures. While there were many subtle differences in the distribution of mammal species and human attitudes towards wildlife on livestock and game farms in the FKC, there were also many similarities. My study has produced results that can be used by the FKC community to better understand how mammals and humans interact across the landscape, information that will ultimately contribute to future conservation planning in the area.
- Full Text:
- Date Issued: 2016
Job Engagement and Coping Strategies as Moderators of the Relationship between Occupational Stress and Burnout among Police Officers in the Eastern Cape, South Africa
- Authors: Dywili, Mtutuzeli
- Date: 2016
- Subjects: Police -- Job stress -- South Africa -- Eastern cape Job satisfaction -- South Africa -- Eastern Cape Employee motivation -- South Africa -- Eastern Cape Work -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7697 , vital:30707
- Description: Police work in South Africa is demanding and stressful. Literature reveals that occupational stress when fully manifest amount to emotional burnout. It was therefore the aim of this study to examine job engagement and coping strategies as moderators of the relationship between occupational stress and burnout among police officers. Using a sample of 377 police officers from the Eastern Cape, South Africa, data was collected using various scales namely; the Effort – Reward Imbalance (ERI) questionnaire (occupational stress), the Maslach Burnout Inventory – General Survey MBI-GS (emotional burnout), the Utrecht Work Engagement Scale (job engagement), and the Coping Orientation to Problems Experienced questionnaire (coping strategies). Correlation tests and regression analysis were ministered on the data to test the research hypotheses. The major finding of the study indicated that job engagement and coping strategies collectively significantly moderate the relationship between occupational stress and emotional burnout. However, job engagement on its own was reported to be an insignificant moderator of the relationship between occupational stress and emotional burnout.
- Full Text:
- Date Issued: 2016
- Authors: Dywili, Mtutuzeli
- Date: 2016
- Subjects: Police -- Job stress -- South Africa -- Eastern cape Job satisfaction -- South Africa -- Eastern Cape Employee motivation -- South Africa -- Eastern Cape Work -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/7697 , vital:30707
- Description: Police work in South Africa is demanding and stressful. Literature reveals that occupational stress when fully manifest amount to emotional burnout. It was therefore the aim of this study to examine job engagement and coping strategies as moderators of the relationship between occupational stress and burnout among police officers. Using a sample of 377 police officers from the Eastern Cape, South Africa, data was collected using various scales namely; the Effort – Reward Imbalance (ERI) questionnaire (occupational stress), the Maslach Burnout Inventory – General Survey MBI-GS (emotional burnout), the Utrecht Work Engagement Scale (job engagement), and the Coping Orientation to Problems Experienced questionnaire (coping strategies). Correlation tests and regression analysis were ministered on the data to test the research hypotheses. The major finding of the study indicated that job engagement and coping strategies collectively significantly moderate the relationship between occupational stress and emotional burnout. However, job engagement on its own was reported to be an insignificant moderator of the relationship between occupational stress and emotional burnout.
- Full Text:
- Date Issued: 2016
Isithako sohlahlubo-bunzululwazi-sakhono kwiimbalo zikaSaule: iinoveli ezintathu = decontsructive stylistic critique of Saule' s writings: the case of three novels
- Jaxa, Nontembiso Patricia, Kwatsha, Linda Loretta
- Authors: Jaxa, Nontembiso Patricia , Kwatsha, Linda Loretta
- Date: 2016
- Subjects: Xhosa literature -- Criticism, Textual , Literature -- Black authors -- History and criticism , South African literature -- History and criticism , Saule, N -- Criticism and interpretation , Saule, N -- Literary style
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/7762 , vital:23830
- Description: Kule ngxoxo kuqwalaselwa ukugqwesa kwesiThako Sohlahlubo-buNzululwazi-sakhono kuhlalutyo loncwadi. Olu phando lugxile ekuduliseni ukuba akukho luzalwano luthe ngqo, kwaye lusisigxina phakathi kwegama nentsingiselo, ngenxa yobumbaxa beentsingiselo zegama. Esi siThako siludondolo ekusinyelelwa ngalo kolu phando, ukuqaqambisa ukuba iitekisi azinantsingiselo izinzileyo. Ke ngoko ibe ayinabunyani mpela ingcamango yokuba igama linokunanyatheliswa intsingiselo ethile, ze loo ntsingiselo ibange ubuntsusa. Ingxoxo yophando, iphendula imibuzo ebuza ubuni besiThako Sohlahlubo-buNzululwazi-sakhono, nokuchana kwaso ekuhlalutyeni iitekisi zoncwadi. Imibuzo ikwabuza izizathu zokungazinzi kwentsingiselo yetekisi, nokungabi nakwalatheka ncam kwentsingiselo ajolise kuyo umbhali, ngotolo lwakhe oluluchongo-sigama. Le mibuzo iyaphenduleka kubuthumbu bengxoxo. Ingxoxo idandalazisa ukunzotshoba kwesi siThako kuhlahlubo, kuqanyelwa ngeengcingane zaso eziphambili. Ukuphendulwa kwemibuzo yophando, kufezekisa iinjongo zophando. Iinoveli ezichongelwe uphando, ziinoveli ezintathu zikaSaule, ezizezi: Ukhozi Olumaphiko, Umlimandlela kunye no-Vuleka Mhlaba, azikhethelwanga kuthelekiswa koko kukudandalazisa elubala ukunyanisa kwesiThako Sohlahlubo-buNzululwazi-sakhono, malunga nomba weentsingiselo. Ngazo, kudula ubunyani bophindaphindeko lwegama elinye kwimixholo ngemixholo, lizale iintsingiselo ezahlukileyo. Kanti, kukwadandalaza ukuba intsingiselo yegama ayixhomekekanga kumxholo, iyakwazi ukutyekeza ngaphaya kwawo, liveze nezinye iintsingiselo. Olu phando lungaluncedo kakhulu kubafundi nootitshala kuba kanye luphethe umba wokuhlalutywa kweetekisi, ngendlela ekhuthazwa yiNkcazelo yePolisi yeKharityhulam nokuHlola (2011). Ebethelela ukuba kufundo loncwadi kufuneka abafundi bayiqhaqhe ukuyihlalutya itekisi ukuze kuvele indlela eyakhiwe neyakheke ngayo, oko ke kukuHlahluba. Kanti ke nakubahlohli lungaluncedo kuba lutyhila okuninzi ngesiThako Sohlahlubo-buNzululwazi-sakhono. Ekuxoxeni, isiThako sobuNzululwazi Mlando-mbali, kurhatyulwe kuso, ukuxhasa imiba ethile kuphando. Ingxoxo Yahlulwe yazizahluko ngolu hlobo: Isahluko sokuqala, sidandalazisa ingxubakaxaka ethunuke yandulula uphando olu. Kwabekwa iinjongo, iziphumo-njongo zophando nemibuzo ekuza kucangcathwa kuyo kuphando. Kwaphengululwa iincwadi zeengcali kwisi-Thako Sohlahlubo-buNzululwazi-sakhono, kwarhewulwa nesiThako sobuNzululwazi beeNkumbulo noMlando-mbali. Isahluko sesibini, luphendululo lweencwadi olunzulileyo nolunabileyo, kupendlwa izimvo ezimalunga nobuni besiThako Sohlahlubo-buNzululwazi-sakhono. Kubekelelwa, kucutyungulwa iingcingane zaso, ezibe ludondolo lophando. Isahluko sesithathu, yingxoxo. Kuphicothwa iinoveli ezichongelwe uphando, zihlahlutywa, kusetyenziswa iingcamango neengcingane zesiThako Sohla-hlubo-buNzululwazi-sakhono. Ikakhulu kuqwalaselwa indlela izibini ezichasana ngokulinganayo ezivela ngayo. Kuduliswa ukuminxiselwa kwezo zikwinqanaba elingezantsi. Isahluko sesine, ingxoxo iyaqhuba, kuqwalselwa ukusetyenziswa kwamaze-nge nemiqondiso, neentsingiselo ezivelayo, nokwahluka kwazo, okukhokelela ukuba utekisi ibe nobuvumephika. Isahluko sesihlanu, uphando luqhubeka kudandalaziswa ukusetyenziswa kwezandi, isigama sokuchaza nezafobe, nemifanekiso-ngqondweni eyakhiwa zezi zixhobo zoncwadi, ze kuphendlwe iintsingiselo nefuthe lazo kwitekisi. Isahluko sesithandathu sigxile ekusetyenzisweni kwembali kuncwadi, ngendlela evuselela iinkumbulo. Kuso nakuba kuhlahlutywa kodwa kunce-diswa ngokurhabula kwisiThako sobuNzululwazi beeNkumbulo noMlando-mbali.
- Full Text:
- Date Issued: 2016
- Authors: Jaxa, Nontembiso Patricia , Kwatsha, Linda Loretta
- Date: 2016
- Subjects: Xhosa literature -- Criticism, Textual , Literature -- Black authors -- History and criticism , South African literature -- History and criticism , Saule, N -- Criticism and interpretation , Saule, N -- Literary style
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/7762 , vital:23830
- Description: Kule ngxoxo kuqwalaselwa ukugqwesa kwesiThako Sohlahlubo-buNzululwazi-sakhono kuhlalutyo loncwadi. Olu phando lugxile ekuduliseni ukuba akukho luzalwano luthe ngqo, kwaye lusisigxina phakathi kwegama nentsingiselo, ngenxa yobumbaxa beentsingiselo zegama. Esi siThako siludondolo ekusinyelelwa ngalo kolu phando, ukuqaqambisa ukuba iitekisi azinantsingiselo izinzileyo. Ke ngoko ibe ayinabunyani mpela ingcamango yokuba igama linokunanyatheliswa intsingiselo ethile, ze loo ntsingiselo ibange ubuntsusa. Ingxoxo yophando, iphendula imibuzo ebuza ubuni besiThako Sohlahlubo-buNzululwazi-sakhono, nokuchana kwaso ekuhlalutyeni iitekisi zoncwadi. Imibuzo ikwabuza izizathu zokungazinzi kwentsingiselo yetekisi, nokungabi nakwalatheka ncam kwentsingiselo ajolise kuyo umbhali, ngotolo lwakhe oluluchongo-sigama. Le mibuzo iyaphenduleka kubuthumbu bengxoxo. Ingxoxo idandalazisa ukunzotshoba kwesi siThako kuhlahlubo, kuqanyelwa ngeengcingane zaso eziphambili. Ukuphendulwa kwemibuzo yophando, kufezekisa iinjongo zophando. Iinoveli ezichongelwe uphando, ziinoveli ezintathu zikaSaule, ezizezi: Ukhozi Olumaphiko, Umlimandlela kunye no-Vuleka Mhlaba, azikhethelwanga kuthelekiswa koko kukudandalazisa elubala ukunyanisa kwesiThako Sohlahlubo-buNzululwazi-sakhono, malunga nomba weentsingiselo. Ngazo, kudula ubunyani bophindaphindeko lwegama elinye kwimixholo ngemixholo, lizale iintsingiselo ezahlukileyo. Kanti, kukwadandalaza ukuba intsingiselo yegama ayixhomekekanga kumxholo, iyakwazi ukutyekeza ngaphaya kwawo, liveze nezinye iintsingiselo. Olu phando lungaluncedo kakhulu kubafundi nootitshala kuba kanye luphethe umba wokuhlalutywa kweetekisi, ngendlela ekhuthazwa yiNkcazelo yePolisi yeKharityhulam nokuHlola (2011). Ebethelela ukuba kufundo loncwadi kufuneka abafundi bayiqhaqhe ukuyihlalutya itekisi ukuze kuvele indlela eyakhiwe neyakheke ngayo, oko ke kukuHlahluba. Kanti ke nakubahlohli lungaluncedo kuba lutyhila okuninzi ngesiThako Sohlahlubo-buNzululwazi-sakhono. Ekuxoxeni, isiThako sobuNzululwazi Mlando-mbali, kurhatyulwe kuso, ukuxhasa imiba ethile kuphando. Ingxoxo Yahlulwe yazizahluko ngolu hlobo: Isahluko sokuqala, sidandalazisa ingxubakaxaka ethunuke yandulula uphando olu. Kwabekwa iinjongo, iziphumo-njongo zophando nemibuzo ekuza kucangcathwa kuyo kuphando. Kwaphengululwa iincwadi zeengcali kwisi-Thako Sohlahlubo-buNzululwazi-sakhono, kwarhewulwa nesiThako sobuNzululwazi beeNkumbulo noMlando-mbali. Isahluko sesibini, luphendululo lweencwadi olunzulileyo nolunabileyo, kupendlwa izimvo ezimalunga nobuni besiThako Sohlahlubo-buNzululwazi-sakhono. Kubekelelwa, kucutyungulwa iingcingane zaso, ezibe ludondolo lophando. Isahluko sesithathu, yingxoxo. Kuphicothwa iinoveli ezichongelwe uphando, zihlahlutywa, kusetyenziswa iingcamango neengcingane zesiThako Sohla-hlubo-buNzululwazi-sakhono. Ikakhulu kuqwalaselwa indlela izibini ezichasana ngokulinganayo ezivela ngayo. Kuduliswa ukuminxiselwa kwezo zikwinqanaba elingezantsi. Isahluko sesine, ingxoxo iyaqhuba, kuqwalselwa ukusetyenziswa kwamaze-nge nemiqondiso, neentsingiselo ezivelayo, nokwahluka kwazo, okukhokelela ukuba utekisi ibe nobuvumephika. Isahluko sesihlanu, uphando luqhubeka kudandalaziswa ukusetyenziswa kwezandi, isigama sokuchaza nezafobe, nemifanekiso-ngqondweni eyakhiwa zezi zixhobo zoncwadi, ze kuphendlwe iintsingiselo nefuthe lazo kwitekisi. Isahluko sesithandathu sigxile ekusetyenzisweni kwembali kuncwadi, ngendlela evuselela iinkumbulo. Kuso nakuba kuhlahlutywa kodwa kunce-diswa ngokurhabula kwisiThako sobuNzululwazi beeNkumbulo noMlando-mbali.
- Full Text:
- Date Issued: 2016
Investigating the nature of the linguistic challenges of the Department of Basic Education (DBE) 2013 Grade 4 Mathematics ANAs and learners’ and teachers’ experience of them.
- Authors: Sibanda, Lucy
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2079 , http://hdl.handle.net/10962/d1021312
- Description: The underperformance of South African learners in literacy and numeracy is a source of grave concern, especially at the transition from Grade 3 to Grade 4. The challenge that complicates this shift is to some extent linguistic, since at Grade 4 in South Africa the majority of learners begin learning in English, which is an additional language for most. The study adopts a sociocultural view of language and learning. Vygotsky’s influential theoretical work on language and learning, in which language is considered central to learning and learning is a social process embedded in sociocultural settings, informs the study. The introduction of the Annual National Assessments (ANAs) across primary and secondary grades in South Africa in mathematics and literacy in 2011 provides the context for this research. It is against this background that the present study aimed, through a case study approach of three Grade 4 classes of English additional language (EAL) learners, to achieve four things, namely: to investigate the linguistic challenges of the 2013 Grade 4 mathematics ANAs; to analyse the learners’ written responses to the 2013 mathematics ANA items; to explore the 2013 Grade 4 learners’ difficulties and experiences of the 2013 mathematics ANAs, and to investigate the Grade 4 mathematics teachers’ perspectives of the language of the ANAs. In order to achieve these aims, the data was collected in four phases. The first phase of the study addressed the nature of the linguistic challenges of the Department of Basic Education Grade 4 mathematics ANAs. Data collection occurred in two parts: 1) Comparing Grade 4 ANAs to exemplars provided and 2) Analysing the language of the 2013 mathematics ANAs. This was done through content analysis and Shaftel et al.’s (2006) linguistic complexity checklist. Findings for part 1 of the study revealed that there were several inconsistencies in the questioning format and language used in the ANAs and in the exemplars. Findings of the content analysis done on the 2013 mathematics ANA test items using Shaftel et al.’s (2006) linguistic complexity checklist and Vale’s (2013) Linguistic Complexity Index formula point to many linguistic complexities in several test items, particularly in relation to recurrent use of: 7 or more letter words, homophones, prepositional phrases and specific mathematics vocabulary across the majority of questions. In phase 2, the analysis of 106 learners’ written responses for the 2013 mathematics ANA questions revealed that for many of the questions the language used was unfamiliar for Grade 4 learners using English as an additional language. This was aggravated by the inclusion in the ANAs of linguistic forms learners would not have encountered in their workbooks or exemplars intended to prepare the learners for the assessments. Therefore, linguistic complexity of items was a key contributing factor to learners’ poor performance in the test. In the third phase, the quantitative and qualitative analysis of the 26 learners’ interviews revealed that during the task-based interviews, learners experienced difficulties in the following skills: reading, comprehension, transformation, process and encoding. The greatest difficulties were experienced in comprehension and in reading, especially in the two classes where the learners were less proficient in the English language. The fourth phase, in which two Grade 4 mathematics teachers’ perceptions of the linguistic demands of the Grade 4 mathematics ANAs were presented and analysed, the teachers’ perceptions indicated that the mathematical language was mostly too difficult for the Grade 4 learners. Teachers also were of the opinion that learners’ reading skills were poor and they struggled to comprehend what they read. A dilemma regarding whether teachers should assist learners during the ANAs, satisfying the local needs for mediating the language or whether they should comply with the ANA policy which states that they may not assist learners was expressed by one of the teachers. A range of language challenges that teachers managed with various strategies were raised. These included one teacher’s use of code-switching during the teaching of mathematics. The study concludes with implications and recommendations. These include that test designers should minimise the language complexity of test items, especially in the early transition grades of learning in English. Research should be conducted on possibilities for allowing teachers to provide linguistic mediation to ANA questions in these transition years of learners learning in English.
- Full Text:
- Date Issued: 2016
- Authors: Sibanda, Lucy
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2079 , http://hdl.handle.net/10962/d1021312
- Description: The underperformance of South African learners in literacy and numeracy is a source of grave concern, especially at the transition from Grade 3 to Grade 4. The challenge that complicates this shift is to some extent linguistic, since at Grade 4 in South Africa the majority of learners begin learning in English, which is an additional language for most. The study adopts a sociocultural view of language and learning. Vygotsky’s influential theoretical work on language and learning, in which language is considered central to learning and learning is a social process embedded in sociocultural settings, informs the study. The introduction of the Annual National Assessments (ANAs) across primary and secondary grades in South Africa in mathematics and literacy in 2011 provides the context for this research. It is against this background that the present study aimed, through a case study approach of three Grade 4 classes of English additional language (EAL) learners, to achieve four things, namely: to investigate the linguistic challenges of the 2013 Grade 4 mathematics ANAs; to analyse the learners’ written responses to the 2013 mathematics ANA items; to explore the 2013 Grade 4 learners’ difficulties and experiences of the 2013 mathematics ANAs, and to investigate the Grade 4 mathematics teachers’ perspectives of the language of the ANAs. In order to achieve these aims, the data was collected in four phases. The first phase of the study addressed the nature of the linguistic challenges of the Department of Basic Education Grade 4 mathematics ANAs. Data collection occurred in two parts: 1) Comparing Grade 4 ANAs to exemplars provided and 2) Analysing the language of the 2013 mathematics ANAs. This was done through content analysis and Shaftel et al.’s (2006) linguistic complexity checklist. Findings for part 1 of the study revealed that there were several inconsistencies in the questioning format and language used in the ANAs and in the exemplars. Findings of the content analysis done on the 2013 mathematics ANA test items using Shaftel et al.’s (2006) linguistic complexity checklist and Vale’s (2013) Linguistic Complexity Index formula point to many linguistic complexities in several test items, particularly in relation to recurrent use of: 7 or more letter words, homophones, prepositional phrases and specific mathematics vocabulary across the majority of questions. In phase 2, the analysis of 106 learners’ written responses for the 2013 mathematics ANA questions revealed that for many of the questions the language used was unfamiliar for Grade 4 learners using English as an additional language. This was aggravated by the inclusion in the ANAs of linguistic forms learners would not have encountered in their workbooks or exemplars intended to prepare the learners for the assessments. Therefore, linguistic complexity of items was a key contributing factor to learners’ poor performance in the test. In the third phase, the quantitative and qualitative analysis of the 26 learners’ interviews revealed that during the task-based interviews, learners experienced difficulties in the following skills: reading, comprehension, transformation, process and encoding. The greatest difficulties were experienced in comprehension and in reading, especially in the two classes where the learners were less proficient in the English language. The fourth phase, in which two Grade 4 mathematics teachers’ perceptions of the linguistic demands of the Grade 4 mathematics ANAs were presented and analysed, the teachers’ perceptions indicated that the mathematical language was mostly too difficult for the Grade 4 learners. Teachers also were of the opinion that learners’ reading skills were poor and they struggled to comprehend what they read. A dilemma regarding whether teachers should assist learners during the ANAs, satisfying the local needs for mediating the language or whether they should comply with the ANA policy which states that they may not assist learners was expressed by one of the teachers. A range of language challenges that teachers managed with various strategies were raised. These included one teacher’s use of code-switching during the teaching of mathematics. The study concludes with implications and recommendations. These include that test designers should minimise the language complexity of test items, especially in the early transition grades of learning in English. Research should be conducted on possibilities for allowing teachers to provide linguistic mediation to ANA questions in these transition years of learners learning in English.
- Full Text:
- Date Issued: 2016
Integrated Algae Pond Systems for the Treatment of Municipal Wastewater
- Authors: Mambo, Mutsa Prudence
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5960 , http://hdl.handle.net/10962/d1021258
- Description: Integrated algae pond systems are a derivation of the Oswald designed advanced integrated wastewater ponding system, and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Integrated algae pond system technology was introduced to South Africa in 1996 and a pilot plant was designed and commissioned at the Belmont Valley wastewater treatment works in Grahamstown. Previous studies showed that this system delivered a final effluent superior to most pond systems deployed in South Africa but that it was unable to meet the general standard for nutrient removal and effluent discharge. This study was initiated to re-appraise integrated algae pond systems and to assess the potential of the technology as an effective municipal sewage treatment system. And more...
- Full Text:
- Date Issued: 2016
- Authors: Mambo, Mutsa Prudence
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5960 , http://hdl.handle.net/10962/d1021258
- Description: Integrated algae pond systems are a derivation of the Oswald designed advanced integrated wastewater ponding system, and combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Integrated algae pond system technology was introduced to South Africa in 1996 and a pilot plant was designed and commissioned at the Belmont Valley wastewater treatment works in Grahamstown. Previous studies showed that this system delivered a final effluent superior to most pond systems deployed in South Africa but that it was unable to meet the general standard for nutrient removal and effluent discharge. This study was initiated to re-appraise integrated algae pond systems and to assess the potential of the technology as an effective municipal sewage treatment system. And more...
- Full Text:
- Date Issued: 2016
Institutional change, institutional isolation and biodiversity governance in South Africa: a case study of the trout industry in alien and invasive species regulatory reforms
- Authors: Marire, Juniours
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/639 , vital:19977
- Description: The world, in recent decades, has witnessed an incalculable surge in global “wicked” policy problems that have long-term, and most often irreversible, impacts, not least terrorism, climate change, biodiversity losses and desertification. Wicked problems are wicked because there is no single epistemological system that can adequately coordinate policy action for addressing them. Literature abounds with international case studies of opposition to national institutions that are designed to put into effect global and regional policies for resolving wicked problems. This raises questions about what constitutes reasonable institutions, how such institutions can be designed and why societies sometimes fail to develop such institutions despite the obvious need for them. As a point of entry into these issues, the thesis adapted and extended the Northean (2007, 2012) macro meta-theoretic framework for studying the violence-development relationship, which focuses on the role of political and economic competition in the emergence of ‘right’ institutions that promote development, while containing violence. The Northean framework conceptualises two mutually exclusive social orders – the limited access order and the open access order – which provide the socio-cultural context for the evolution of specific institutions. The macro meta-theoretic framework was transformed into a micro metatheoretic framework in such a way that the limited access order and the open access order co-existed in the evolution of specific institutions. This reconceptualisation built on Bromley’s (2004, 2006) two realms of public policy: the realm of reasons (legislative-judicial system) and the realm of rules (administrative system) as well as the feminist concept of epistemic violence, which broadened the concept of violence from being exclusively physical to including the sociocognitive. The feminist concept of epistemic oppression logically fitted into, and became a new sub-category of, Commons’ (1899, 1924, 1934) theories of sovereignty and negotiational psychology. The innovations showed that either of these realms can be a limited access order, while the other can be an open access order or both can be open access orders or both can be limited access orders. The conceptual innovations were then used as an interpretive scheme in analysing the evolution of the South African invasive alien species regulatory reforms under the National Environmental Management: Biodiversity Act of 2004, using a case study of the trout sector, which was the most opposed to the reforms. There was a general perception among socioeconomic sectors that utilise invasive alien species that the regulatory reform processes for the governance of such species had institutionally isolated the sectors. Because of this perception, the regulatory reform process was contested, and implementation of the Fifth Chapter of the Act, which deals with the governance of invasive alien species, was delayed for nearly a decade. The thesis evaluated whether institutional isolation existed and how and why it came to be since it has implications for the reasonableness of emerging regulatory institutions, economic performance of sectors and efficient allocation of fiscal resources in institutional design processes. A mixed methods methodology was used, which included data analysis techniques such as semiosis, exploratory factor analysis, econometric estimation and document analysis. Policy documents, an online survey and key informant interviews comprised the data. The findings suggested six dimensions of institutional change that a theory of institutional change might have to address: the origin and continuity of pecuniary institutions; selfreinforcing mechanisms of the limited access policymaking order; succession and disbandment of the limited access policymaking order; exclusivity of negotiations in institutional design; tiers of institutional isolation; and the role of administrative discontinuities. Findings suggested that institutional isolation existed in the regulatory process, manifesting in three forms: administrative isolation, epistemological isolation and sectoral isolation. Administrative isolation was the most complex of the three in that it also involved a less obvious process of institutional isolation in the form of administrative redefinition of opportunity sets that were already legislatively redefined. The mechanisms of institutional isolation through which administrative isolation was sustained were administrative financing of research and careerism. The two mechanisms created a revolving door-type scenario through which invasion biologists supplied the administrative agency with candidates for senior (decision making) positions and the administrative agency, in turn, demanded specific types of knowledge over which the same epistemic community had a monopoly. The revolving door-type scenario was found to ideologically and physically entrench invasion biologists into the regulatory community. The consequence of the entrenchment was institutional hegemony, which manifested itself through the mechanism of epistemic violence insofar as the invasion biologists became the epistemic arbiters about what kinds of ideas and institutions really mattered in the governance of invasive alien species. Econometric estimates suggested that the extent to which an emerging institution is perceived to be reasonable by regulated sectors depends on the extent to which the institution is designed in a participatory and inclusive manner (that is, using integrative knowledge systems), the extent to which the designers used credible evidence and contextualised international evidence as well as the extent to which the emergent biodiversity governance institution was anthropocentric. However, findings suggested that the South African regulatory reform process fell short on all these four dimensions of reasonable institutions, which is characteristic of institutional design process shaped by hegemonic social imaginaries, resulting in institutional isolation. Emerging from the findings are several theoretical insights. Bush’s (1987) concept of institutional spaces under the Veblenian Dichotomy was extended, the result of which was identification of two stable institutional equilibria – one ceremonial and another instrumental. The ceremonial equilibrium was a typical limited access policymaking order and was responsible for the historical and present emergence of regressive institutions. Findings also suggested that the entrenched invasion biologists ceremonially encapsulated the knowledge fund that had been accumulated since the 1980s, which could have facilitated the consensual design of regulatory institutions for invasive alien species without protracted controversy. Findings suggested that a limited access policymaking order could only be disbanded by the intervention of an external sovereign agent (in this case the office of the state president) since the administrative agency, and the epistemic community that advised it, adopted the solutions that were empirically tested and proposed in the 1980s only after the intervention of the external sovereign agent. The instrumental equilibrium repealed the contested prisoner’s dilemma that was characteristic of the policy process and turned it into an assurance policy game by facilitating the identification of common interests. This finding logically links the study to a recent theoretical development in institutional theory – Ordonomics – which focuses on the causality between ideas and institutions. The findings imply that it is possible to design reasonable institutions as long as integrative (transdisciplinary) knowledge systems, including the non-scientific knowledge of the resource users, are incorporated. Integrative knowledge systems facilitate semantic innovations, which create social DNA, but epistemic violence destroys social DNA. They also imply that reliance on unidisciplinary knowledge systems in institutional design induces a large and inefficient transaction cost burden of public policy on the fiscus and private agents alike because of the inevitability of controversy, especially for wicked policy problems.
- Full Text:
- Date Issued: 2016
- Authors: Marire, Juniours
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/639 , vital:19977
- Description: The world, in recent decades, has witnessed an incalculable surge in global “wicked” policy problems that have long-term, and most often irreversible, impacts, not least terrorism, climate change, biodiversity losses and desertification. Wicked problems are wicked because there is no single epistemological system that can adequately coordinate policy action for addressing them. Literature abounds with international case studies of opposition to national institutions that are designed to put into effect global and regional policies for resolving wicked problems. This raises questions about what constitutes reasonable institutions, how such institutions can be designed and why societies sometimes fail to develop such institutions despite the obvious need for them. As a point of entry into these issues, the thesis adapted and extended the Northean (2007, 2012) macro meta-theoretic framework for studying the violence-development relationship, which focuses on the role of political and economic competition in the emergence of ‘right’ institutions that promote development, while containing violence. The Northean framework conceptualises two mutually exclusive social orders – the limited access order and the open access order – which provide the socio-cultural context for the evolution of specific institutions. The macro meta-theoretic framework was transformed into a micro metatheoretic framework in such a way that the limited access order and the open access order co-existed in the evolution of specific institutions. This reconceptualisation built on Bromley’s (2004, 2006) two realms of public policy: the realm of reasons (legislative-judicial system) and the realm of rules (administrative system) as well as the feminist concept of epistemic violence, which broadened the concept of violence from being exclusively physical to including the sociocognitive. The feminist concept of epistemic oppression logically fitted into, and became a new sub-category of, Commons’ (1899, 1924, 1934) theories of sovereignty and negotiational psychology. The innovations showed that either of these realms can be a limited access order, while the other can be an open access order or both can be open access orders or both can be limited access orders. The conceptual innovations were then used as an interpretive scheme in analysing the evolution of the South African invasive alien species regulatory reforms under the National Environmental Management: Biodiversity Act of 2004, using a case study of the trout sector, which was the most opposed to the reforms. There was a general perception among socioeconomic sectors that utilise invasive alien species that the regulatory reform processes for the governance of such species had institutionally isolated the sectors. Because of this perception, the regulatory reform process was contested, and implementation of the Fifth Chapter of the Act, which deals with the governance of invasive alien species, was delayed for nearly a decade. The thesis evaluated whether institutional isolation existed and how and why it came to be since it has implications for the reasonableness of emerging regulatory institutions, economic performance of sectors and efficient allocation of fiscal resources in institutional design processes. A mixed methods methodology was used, which included data analysis techniques such as semiosis, exploratory factor analysis, econometric estimation and document analysis. Policy documents, an online survey and key informant interviews comprised the data. The findings suggested six dimensions of institutional change that a theory of institutional change might have to address: the origin and continuity of pecuniary institutions; selfreinforcing mechanisms of the limited access policymaking order; succession and disbandment of the limited access policymaking order; exclusivity of negotiations in institutional design; tiers of institutional isolation; and the role of administrative discontinuities. Findings suggested that institutional isolation existed in the regulatory process, manifesting in three forms: administrative isolation, epistemological isolation and sectoral isolation. Administrative isolation was the most complex of the three in that it also involved a less obvious process of institutional isolation in the form of administrative redefinition of opportunity sets that were already legislatively redefined. The mechanisms of institutional isolation through which administrative isolation was sustained were administrative financing of research and careerism. The two mechanisms created a revolving door-type scenario through which invasion biologists supplied the administrative agency with candidates for senior (decision making) positions and the administrative agency, in turn, demanded specific types of knowledge over which the same epistemic community had a monopoly. The revolving door-type scenario was found to ideologically and physically entrench invasion biologists into the regulatory community. The consequence of the entrenchment was institutional hegemony, which manifested itself through the mechanism of epistemic violence insofar as the invasion biologists became the epistemic arbiters about what kinds of ideas and institutions really mattered in the governance of invasive alien species. Econometric estimates suggested that the extent to which an emerging institution is perceived to be reasonable by regulated sectors depends on the extent to which the institution is designed in a participatory and inclusive manner (that is, using integrative knowledge systems), the extent to which the designers used credible evidence and contextualised international evidence as well as the extent to which the emergent biodiversity governance institution was anthropocentric. However, findings suggested that the South African regulatory reform process fell short on all these four dimensions of reasonable institutions, which is characteristic of institutional design process shaped by hegemonic social imaginaries, resulting in institutional isolation. Emerging from the findings are several theoretical insights. Bush’s (1987) concept of institutional spaces under the Veblenian Dichotomy was extended, the result of which was identification of two stable institutional equilibria – one ceremonial and another instrumental. The ceremonial equilibrium was a typical limited access policymaking order and was responsible for the historical and present emergence of regressive institutions. Findings also suggested that the entrenched invasion biologists ceremonially encapsulated the knowledge fund that had been accumulated since the 1980s, which could have facilitated the consensual design of regulatory institutions for invasive alien species without protracted controversy. Findings suggested that a limited access policymaking order could only be disbanded by the intervention of an external sovereign agent (in this case the office of the state president) since the administrative agency, and the epistemic community that advised it, adopted the solutions that were empirically tested and proposed in the 1980s only after the intervention of the external sovereign agent. The instrumental equilibrium repealed the contested prisoner’s dilemma that was characteristic of the policy process and turned it into an assurance policy game by facilitating the identification of common interests. This finding logically links the study to a recent theoretical development in institutional theory – Ordonomics – which focuses on the causality between ideas and institutions. The findings imply that it is possible to design reasonable institutions as long as integrative (transdisciplinary) knowledge systems, including the non-scientific knowledge of the resource users, are incorporated. Integrative knowledge systems facilitate semantic innovations, which create social DNA, but epistemic violence destroys social DNA. They also imply that reliance on unidisciplinary knowledge systems in institutional design induces a large and inefficient transaction cost burden of public policy on the fiscus and private agents alike because of the inevitability of controversy, especially for wicked policy problems.
- Full Text:
- Date Issued: 2016
Influence of increased processing speed on the microstructure evolution and mechanical property relationship in friction stir welding of AA5182-H111 (T500)
- Authors: Bernard, Dreyer
- Date: 2016
- Subjects: Friction stir welding , Aluminum alloys -- Welding
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/7322 , vital:21319
- Description: Friction stir welding of 5xxx series aluminium is generally carried out at low travel speeds, which limits the commercial applications of this process. This manuscript discusses the dynamic eformation characteristics of AA5182-H111 (T500), which allowed a travel speed of 1500 mm/min to be realised. This was achieved by using a spindle speed of 500 rev/min; the same as that required to make a weld of 200 mm/min. The thermal cycles, microstructural evolution due to tool / work-piece interaction, and the local microstructural and mechanical properties of the completed weld are discussed for a travel speed for 200 mm/min and 1500 mm/min. At a rate of 200 mm/min, heat generated due to contact between the shoulder and work-piece surface was transferred ahead of the tool, driving dynamic recrystallization which lowered the flow stress. Hereafter the material entered the stir zone where it was extruded around the pin during a process of continuous dynamic crystallization. At a travel speed of 1500 mm/min, the rate of heat conduction ahead of the tool was not rapid enough, and the material was deformed at low temperatures. A low weld pitch rotations per unit length travelled) was required to ensure that the material was sufficiently strained, to allow the formation of geometric necessary boundaries, which resulted in grain subdivision. The number of high angle grain boundaries was increased through subdivision, thus, increasing the nucleation sites for dynamically recrystallized necklace grains to form. In the absence of heat conduction from the shoulder, the high plastic strain ahead of the tool provided the energy required to drive dynamic recrystallization. Heat was generated from the high plastic strain and during recrystallization, where the stored plastic energy was adiabatically released. Once the material entered the stir zone, the high strain rates associated with the tool rotation which drove dynamic recrystallization that allowed the material to reach high levels of strain, resulted significant grain refinement. The weld zone of the 200 mm/min displayed weld a slight increase in yield strength, with respect to the parent material, due to grain refinement to 10 μm, while the yield strength of the 1500 mm/min weld was significantly increased due to grain refinement to 5 μm. The high weld speed did, however, generate high tensile residual stresses. This work is not only significant for the field of friction stir welding, but also in terms of material processing. The dynamic deformation characteristics associated with Al-5Mg-Mn, alloys which was observed ahead of the tool, is of high value in processes where plastic deformation is applied to improve the mechanical properties of these alloys.
- Full Text:
- Date Issued: 2016
- Authors: Bernard, Dreyer
- Date: 2016
- Subjects: Friction stir welding , Aluminum alloys -- Welding
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/7322 , vital:21319
- Description: Friction stir welding of 5xxx series aluminium is generally carried out at low travel speeds, which limits the commercial applications of this process. This manuscript discusses the dynamic eformation characteristics of AA5182-H111 (T500), which allowed a travel speed of 1500 mm/min to be realised. This was achieved by using a spindle speed of 500 rev/min; the same as that required to make a weld of 200 mm/min. The thermal cycles, microstructural evolution due to tool / work-piece interaction, and the local microstructural and mechanical properties of the completed weld are discussed for a travel speed for 200 mm/min and 1500 mm/min. At a rate of 200 mm/min, heat generated due to contact between the shoulder and work-piece surface was transferred ahead of the tool, driving dynamic recrystallization which lowered the flow stress. Hereafter the material entered the stir zone where it was extruded around the pin during a process of continuous dynamic crystallization. At a travel speed of 1500 mm/min, the rate of heat conduction ahead of the tool was not rapid enough, and the material was deformed at low temperatures. A low weld pitch rotations per unit length travelled) was required to ensure that the material was sufficiently strained, to allow the formation of geometric necessary boundaries, which resulted in grain subdivision. The number of high angle grain boundaries was increased through subdivision, thus, increasing the nucleation sites for dynamically recrystallized necklace grains to form. In the absence of heat conduction from the shoulder, the high plastic strain ahead of the tool provided the energy required to drive dynamic recrystallization. Heat was generated from the high plastic strain and during recrystallization, where the stored plastic energy was adiabatically released. Once the material entered the stir zone, the high strain rates associated with the tool rotation which drove dynamic recrystallization that allowed the material to reach high levels of strain, resulted significant grain refinement. The weld zone of the 200 mm/min displayed weld a slight increase in yield strength, with respect to the parent material, due to grain refinement to 10 μm, while the yield strength of the 1500 mm/min weld was significantly increased due to grain refinement to 5 μm. The high weld speed did, however, generate high tensile residual stresses. This work is not only significant for the field of friction stir welding, but also in terms of material processing. The dynamic deformation characteristics associated with Al-5Mg-Mn, alloys which was observed ahead of the tool, is of high value in processes where plastic deformation is applied to improve the mechanical properties of these alloys.
- Full Text:
- Date Issued: 2016
Implementation of gender equality policies to enhance female leadership in Zimbabwean universities : towards a comprehensive framework
- Chitsamatanga, Bellita Banda
- Authors: Chitsamatanga, Bellita Banda
- Date: 2016
- Subjects: Sex differences in education Discrimination in education Women executives
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/13571 , vital:39680
- Description: This study critically examined the implementation of gender equality policies to enhance female leadership in Zimbabwean universities. Three theoretical frameworks were adopted for this study which were: The feminist critical policy analysis, top-down and bottom-up policy implementation theories. Within this study an interpretive paradigm which aligned with the qualitative approach and the case study design to better understand the phenomena were adopted. The study covered two state universities in Zimbabwe which were purposively selected. The participants who comprised Pro Vice Chancellors, Deputy Registrars Human Resources, Faculty Deans, Director of Gender Schools, Senior Administrative Registrars, Chairpersons of Departments and males and female academics were also purposively selected. Semi structured interviews, focus group discussion and document analysis were used as data collection instruments. Data were analysed using content analysis and the emerging results were organised into different themes reflective of the participant’s responses. The findings of the study presuppose that the state universities Zimbabwe were implementing gender sensitive organisational culture through open door policy and this promoted transformational leadership in both universities. The study revealed that both universities consulted internal and external gender experts and top-down and bottom-up consultations were made during policy formulation. It was discovered from the study that both universities had also utilised gender mainstreaming and affirmative action as strategies for promoting female leadership and gender equality. Despite teaching and learning, community engagement, research, recruitment and promotions which were used to promote the gender agenda, there were indications that these were being implemented in a haphazard manner. This adversely influenced active participation of females in decision making processes. The collected data also showed that both universities had enacted gender structures which were in line with international, regional and national gender policies and conventions and were being used to irradiate the importance of having gender parity in top positions. The findings of the study further illuminated that monitoring and evaluation of the gender equality policy and programs in place to advance females to leadership positions had not been done, leading to major impediments to achievement of gender balance. There also emerged a number of challenges which were uniform in both universities namely; lack of gender knowledge; commitment, lack of gender training and workshops, lack of consultation using bottom-up approach, gender budgeting and inadequate resources. Though the above mentioned were identified as encumbering features in both universities there was a substantiation of pockets of good practices. These were; implementation of gender equality policy, involvement of internal and external gender experts to policy formulation; promotion of shared power and authentic leadership through transparent selection of chairperson of departments; gender workshop and training; staff development programmes; enactment of gender structures, enhanced community engagement and liaison with NGOs to promote gender agenda at all levels. Regardless of the number of hurdles that indicate that universities continue to be fraught with challenges in promoting female leadership, the pockets of good practices are evidence that both universities are making positive strides through the implementation of gender equality policies to enhance female leadership. Therefore, to benchmark changes in universities, the study recommends that transformational leadership must permeate in all university structures to promote an organisational culture that is gender sensitive. There must be adequate resources, gender training and workshops; focal persons and points; commitment and political will, gender experts from governmental to ministerial levels and satellite gender structures. Monitoring and evaluation should be carried out in both universities and this should be guided by a framework so as to assist universities to tap into female empowerment and gender equality that will promote the interests of both genders, while retaining the quality and excellence in universities. Lastly, the findings of the study and the extant literature are indicative that enhancement of female leadership in universities is currently affected by a number of challenges. Therefore, as part of redress, the researcher recommends a comprehensive framework which illuminates pockets of good practices in implementing gender equality policies to enhance female leadership in universities.
- Full Text:
- Date Issued: 2016
- Authors: Chitsamatanga, Bellita Banda
- Date: 2016
- Subjects: Sex differences in education Discrimination in education Women executives
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/13571 , vital:39680
- Description: This study critically examined the implementation of gender equality policies to enhance female leadership in Zimbabwean universities. Three theoretical frameworks were adopted for this study which were: The feminist critical policy analysis, top-down and bottom-up policy implementation theories. Within this study an interpretive paradigm which aligned with the qualitative approach and the case study design to better understand the phenomena were adopted. The study covered two state universities in Zimbabwe which were purposively selected. The participants who comprised Pro Vice Chancellors, Deputy Registrars Human Resources, Faculty Deans, Director of Gender Schools, Senior Administrative Registrars, Chairpersons of Departments and males and female academics were also purposively selected. Semi structured interviews, focus group discussion and document analysis were used as data collection instruments. Data were analysed using content analysis and the emerging results were organised into different themes reflective of the participant’s responses. The findings of the study presuppose that the state universities Zimbabwe were implementing gender sensitive organisational culture through open door policy and this promoted transformational leadership in both universities. The study revealed that both universities consulted internal and external gender experts and top-down and bottom-up consultations were made during policy formulation. It was discovered from the study that both universities had also utilised gender mainstreaming and affirmative action as strategies for promoting female leadership and gender equality. Despite teaching and learning, community engagement, research, recruitment and promotions which were used to promote the gender agenda, there were indications that these were being implemented in a haphazard manner. This adversely influenced active participation of females in decision making processes. The collected data also showed that both universities had enacted gender structures which were in line with international, regional and national gender policies and conventions and were being used to irradiate the importance of having gender parity in top positions. The findings of the study further illuminated that monitoring and evaluation of the gender equality policy and programs in place to advance females to leadership positions had not been done, leading to major impediments to achievement of gender balance. There also emerged a number of challenges which were uniform in both universities namely; lack of gender knowledge; commitment, lack of gender training and workshops, lack of consultation using bottom-up approach, gender budgeting and inadequate resources. Though the above mentioned were identified as encumbering features in both universities there was a substantiation of pockets of good practices. These were; implementation of gender equality policy, involvement of internal and external gender experts to policy formulation; promotion of shared power and authentic leadership through transparent selection of chairperson of departments; gender workshop and training; staff development programmes; enactment of gender structures, enhanced community engagement and liaison with NGOs to promote gender agenda at all levels. Regardless of the number of hurdles that indicate that universities continue to be fraught with challenges in promoting female leadership, the pockets of good practices are evidence that both universities are making positive strides through the implementation of gender equality policies to enhance female leadership. Therefore, to benchmark changes in universities, the study recommends that transformational leadership must permeate in all university structures to promote an organisational culture that is gender sensitive. There must be adequate resources, gender training and workshops; focal persons and points; commitment and political will, gender experts from governmental to ministerial levels and satellite gender structures. Monitoring and evaluation should be carried out in both universities and this should be guided by a framework so as to assist universities to tap into female empowerment and gender equality that will promote the interests of both genders, while retaining the quality and excellence in universities. Lastly, the findings of the study and the extant literature are indicative that enhancement of female leadership in universities is currently affected by a number of challenges. Therefore, as part of redress, the researcher recommends a comprehensive framework which illuminates pockets of good practices in implementing gender equality policies to enhance female leadership in universities.
- Full Text:
- Date Issued: 2016
Impact of a holistic lifestyle management education programme on health and education outcomes of socioeconomically disadvantaged university students
- Authors: Morris-Paxton, Angela Ann
- Date: 2016
- Subjects: College students -- Mental health College students -- Health and hygiene Health promotion
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11909 , vital:27003
- Description: Disorders of lifestyle are increasing globally; countries in transition are suffering the double burden of both contagious and chronic disorders. The utilization of health education to address these issues has had variable results, but the most successful have incorporated human contact. The aim of this study was to measure the quantitative and qualitative impact of a wellness promotion programme on university students. The objective was to provide a structured facilitated holistic wellness education programme to a sample of socioeconomically disadvantaged students in Higher Education in the Eastern Cape Province, South Africa. Using a pragmatic mixed methodological approach to this critical evaluation, the impact on both wellness and academic progress was measured. Initial demographic data was gathered via a biographical questionnaire, pre- and post-intervention measurement of wellness, using the Wellness Questionnaire for Higher Education, as well as a semi-structured qualitative questionnaire and transcripts of academic results. Quantitative data was analysed using SPSS analysis software and qualitative data using the NVivo analysis package. The findings were that all students improved throughout the year in their overall wellness scores, in particular in areas such as avoiding excessive sun exposure and increasing the amount of physical exercise. This corresponded with an increase in the value that the participants attached to information on these aspects of wellness, which was attributed to the programme. Results revealed that there was a weak correlation between student wellness measured at the year-end and academic success overall, but a strong correlation between student wellness and academic success for the students that gained the highest marks. Analysis of the dimensions of wellness that correlated best with student success revealed that there was a particularly strong correlation between year-end career wellness and year-end academic success. In conclusion it was found that a positive and holistic salutogenic wellness education programme increased levels of student wellness overall, which translated into student academic success. The link between wellness and success was particularly strong in students that gained higher marks. Recommendations include that first-year higher education students receive a positive wellness education programme built into the curriculum of their first year of study and that the overall impact be monitored across a broader spectrum of students over the duration of their diploma or degree programme.
- Full Text:
- Date Issued: 2016
- Authors: Morris-Paxton, Angela Ann
- Date: 2016
- Subjects: College students -- Mental health College students -- Health and hygiene Health promotion
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11909 , vital:27003
- Description: Disorders of lifestyle are increasing globally; countries in transition are suffering the double burden of both contagious and chronic disorders. The utilization of health education to address these issues has had variable results, but the most successful have incorporated human contact. The aim of this study was to measure the quantitative and qualitative impact of a wellness promotion programme on university students. The objective was to provide a structured facilitated holistic wellness education programme to a sample of socioeconomically disadvantaged students in Higher Education in the Eastern Cape Province, South Africa. Using a pragmatic mixed methodological approach to this critical evaluation, the impact on both wellness and academic progress was measured. Initial demographic data was gathered via a biographical questionnaire, pre- and post-intervention measurement of wellness, using the Wellness Questionnaire for Higher Education, as well as a semi-structured qualitative questionnaire and transcripts of academic results. Quantitative data was analysed using SPSS analysis software and qualitative data using the NVivo analysis package. The findings were that all students improved throughout the year in their overall wellness scores, in particular in areas such as avoiding excessive sun exposure and increasing the amount of physical exercise. This corresponded with an increase in the value that the participants attached to information on these aspects of wellness, which was attributed to the programme. Results revealed that there was a weak correlation between student wellness measured at the year-end and academic success overall, but a strong correlation between student wellness and academic success for the students that gained the highest marks. Analysis of the dimensions of wellness that correlated best with student success revealed that there was a particularly strong correlation between year-end career wellness and year-end academic success. In conclusion it was found that a positive and holistic salutogenic wellness education programme increased levels of student wellness overall, which translated into student academic success. The link between wellness and success was particularly strong in students that gained higher marks. Recommendations include that first-year higher education students receive a positive wellness education programme built into the curriculum of their first year of study and that the overall impact be monitored across a broader spectrum of students over the duration of their diploma or degree programme.
- Full Text:
- Date Issued: 2016
Higher order modulation formats for high speed optical communication systems with digital signal processing aided receiver
- Chabata, Tichakunda Valentine
- Authors: Chabata, Tichakunda Valentine
- Date: 2016
- Subjects: Optical communications , Modulation (Electronics) , Signal processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/4775 , vital:20677
- Description: The drastic increase in the number of internet users and the general convergence of all other communication systems into an optical system have brought a sharp rise in demand for bandwidth and calls for high capacity transmission networks. Large unamplified transmission reach is another contributor in reducing deployment costs of an optical communication system. Spectrally efficient modulation formats are suggested as a solution to overcome the problems associated with limited channels and bandwidth of dense wavelength division multiplexing (DWDM) optical communication systems. Higher order modulation formats which are considered to be spectrally efficient and can increase the transmission capacity by transmitting more information in the amplitude, phase, polarization or a combination of all was studied. Different detection technologies are to be implemented to suit a particular higher order modulation format. In this research multilevel modulation formats, different detection technologies and a digital signal processing aided receiver were studied in a practical optical transmission system. The work in this thesis started with the implementation of the traditional amplitude shift keying (ASK) modulation and a differential phase shift keying (DPSK) modulation systems as they form the basic building block in the design of higher order modulation formats. Results obtained from using virtual photonics instruments (VPI)simulation software, receiver sensitivity for 10Gbpsnon-return-to-zero (NRZ), amplitude phase shift keying (ASK) and DPSK signals were measured to be -22.7 dBm and -22.0 dBm respectively. Performance comparison for the two modulation formats were done over different transmission distances. ASK also known as On-Off keying (OOK) performed better for shorter lengths whereas DPSK performed better for longer lengths of up to90km.Experimental results on a 10 Gbps NRZ- ASK signal gave a receiver sensitivity of -21.1 dBm from digital signal processing (DSP) aided receiver against -19.8 dBm from the commercial bit error ratio tester (BERT) yielding a small difference of 1.3 dB hence validating the reliability and accuracy of the digital signal processing (DSP) assisted receiver. Traditional direct detection scheme and coherent detection scheme performances were evaluated again on a 10 Gbps NRZ ASK signal. Coherent detection that can achieve a large unamplified transmission reach and has a higher passive optical splitting ratio was first evaluated using the VPI simulation software. Simulation results gave a receiver sensitivity of -30.4 dBm forcoherent detection and -18.3 dBm for direct detection, yielding a gain in receiver sensitivity of 12.1 dB. The complex coherently detected signal, from the experimental setup gave a receiver sensitivity of -20.6 dBm with a gain in receiver sensitivity of 3.5 dBm with respect to direct detection. A multilevel pulse amplitude modulation (4-PAM) that doubles the data rate per channel from10 Gbps to 20 Gbps by transmitting more information in the amplitude of the carrier signal was implemented. This was achieved by modulating the optical amplitude with an electrical four level amplitude shift keyed (ASK) signal. A receiver consisting of a single photodiode, three decision circuits and a decoding logic circuit was used to receive and extract the original transmitted data. A DSP aided receiver was used to evaluate the link performance. A receiver sensitivity of -12.8 dBm is attained with a dispersion penalty of about 7.2 dB after transmission through 25 km of G.652 fibre.
- Full Text:
- Date Issued: 2016
- Authors: Chabata, Tichakunda Valentine
- Date: 2016
- Subjects: Optical communications , Modulation (Electronics) , Signal processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/4775 , vital:20677
- Description: The drastic increase in the number of internet users and the general convergence of all other communication systems into an optical system have brought a sharp rise in demand for bandwidth and calls for high capacity transmission networks. Large unamplified transmission reach is another contributor in reducing deployment costs of an optical communication system. Spectrally efficient modulation formats are suggested as a solution to overcome the problems associated with limited channels and bandwidth of dense wavelength division multiplexing (DWDM) optical communication systems. Higher order modulation formats which are considered to be spectrally efficient and can increase the transmission capacity by transmitting more information in the amplitude, phase, polarization or a combination of all was studied. Different detection technologies are to be implemented to suit a particular higher order modulation format. In this research multilevel modulation formats, different detection technologies and a digital signal processing aided receiver were studied in a practical optical transmission system. The work in this thesis started with the implementation of the traditional amplitude shift keying (ASK) modulation and a differential phase shift keying (DPSK) modulation systems as they form the basic building block in the design of higher order modulation formats. Results obtained from using virtual photonics instruments (VPI)simulation software, receiver sensitivity for 10Gbpsnon-return-to-zero (NRZ), amplitude phase shift keying (ASK) and DPSK signals were measured to be -22.7 dBm and -22.0 dBm respectively. Performance comparison for the two modulation formats were done over different transmission distances. ASK also known as On-Off keying (OOK) performed better for shorter lengths whereas DPSK performed better for longer lengths of up to90km.Experimental results on a 10 Gbps NRZ- ASK signal gave a receiver sensitivity of -21.1 dBm from digital signal processing (DSP) aided receiver against -19.8 dBm from the commercial bit error ratio tester (BERT) yielding a small difference of 1.3 dB hence validating the reliability and accuracy of the digital signal processing (DSP) assisted receiver. Traditional direct detection scheme and coherent detection scheme performances were evaluated again on a 10 Gbps NRZ ASK signal. Coherent detection that can achieve a large unamplified transmission reach and has a higher passive optical splitting ratio was first evaluated using the VPI simulation software. Simulation results gave a receiver sensitivity of -30.4 dBm forcoherent detection and -18.3 dBm for direct detection, yielding a gain in receiver sensitivity of 12.1 dB. The complex coherently detected signal, from the experimental setup gave a receiver sensitivity of -20.6 dBm with a gain in receiver sensitivity of 3.5 dBm with respect to direct detection. A multilevel pulse amplitude modulation (4-PAM) that doubles the data rate per channel from10 Gbps to 20 Gbps by transmitting more information in the amplitude of the carrier signal was implemented. This was achieved by modulating the optical amplitude with an electrical four level amplitude shift keyed (ASK) signal. A receiver consisting of a single photodiode, three decision circuits and a decoding logic circuit was used to receive and extract the original transmitted data. A DSP aided receiver was used to evaluate the link performance. A receiver sensitivity of -12.8 dBm is attained with a dispersion penalty of about 7.2 dB after transmission through 25 km of G.652 fibre.
- Full Text:
- Date Issued: 2016
GPU Accelerated protocol analysis for large and long-term traffic traces
- Nottingham, Alastair Timothy
- Authors: Nottingham, Alastair Timothy
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/910 , vital:20002
- Description: This thesis describes the design and implementation of GPF+, a complete general packet classification system developed using Nvidia CUDA for Compute Capability 3.5+ GPUs. This system was developed with the aim of accelerating the analysis of arbitrary network protocols within network traffic traces using inexpensive, massively parallel commodity hardware. GPF+ and its supporting components are specifically intended to support the processing of large, long-term network packet traces such as those produced by network telescopes, which are currently difficult and time consuming to analyse. The GPF+ classifier is based on prior research in the field, which produced a prototype classifier called GPF, targeted at Compute Capability 1.3 GPUs. GPF+ greatly extends the GPF model, improving runtime flexibility and scalability, whilst maintaining high execution efficiency. GPF+ incorporates a compact, lightweight registerbased state machine that supports massively-parallel, multi-match filter predicate evaluation, as well as efficient arbitrary field extraction. GPF+ tracks packet composition during execution, and adjusts processing at runtime to avoid redundant memory transactions and unnecessary computation through warp-voting. GPF+ additionally incorporates a 128-bit in-thread cache, accelerated through register shuffling, to accelerate access to packet data in slow GPU global memory. GPF+ uses a high-level DSL to simplify protocol and filter creation, whilst better facilitating protocol reuse. The system is supported by a pipeline of multi-threaded high-performance host components, which communicate asynchronously through 0MQ messaging middleware to buffer, index, and dispatch packet data on the host system. The system was evaluated using high-end Kepler (Nvidia GTX Titan) and entry level Maxwell (Nvidia GTX 750) GPUs. The results of this evaluation showed high system performance, limited only by device side IO (600MBps) in all tests. GPF+ maintained high occupancy and device utilisation in all tests, without significant serialisation, and showed improved scaling to more complex filter sets. Results were used to visualise captures of up to 160 GB in seconds, and to extract and pre-filter captures small enough to be easily analysed in applications such as Wireshark.
- Full Text:
- Date Issued: 2016
- Authors: Nottingham, Alastair Timothy
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/910 , vital:20002
- Description: This thesis describes the design and implementation of GPF+, a complete general packet classification system developed using Nvidia CUDA for Compute Capability 3.5+ GPUs. This system was developed with the aim of accelerating the analysis of arbitrary network protocols within network traffic traces using inexpensive, massively parallel commodity hardware. GPF+ and its supporting components are specifically intended to support the processing of large, long-term network packet traces such as those produced by network telescopes, which are currently difficult and time consuming to analyse. The GPF+ classifier is based on prior research in the field, which produced a prototype classifier called GPF, targeted at Compute Capability 1.3 GPUs. GPF+ greatly extends the GPF model, improving runtime flexibility and scalability, whilst maintaining high execution efficiency. GPF+ incorporates a compact, lightweight registerbased state machine that supports massively-parallel, multi-match filter predicate evaluation, as well as efficient arbitrary field extraction. GPF+ tracks packet composition during execution, and adjusts processing at runtime to avoid redundant memory transactions and unnecessary computation through warp-voting. GPF+ additionally incorporates a 128-bit in-thread cache, accelerated through register shuffling, to accelerate access to packet data in slow GPU global memory. GPF+ uses a high-level DSL to simplify protocol and filter creation, whilst better facilitating protocol reuse. The system is supported by a pipeline of multi-threaded high-performance host components, which communicate asynchronously through 0MQ messaging middleware to buffer, index, and dispatch packet data on the host system. The system was evaluated using high-end Kepler (Nvidia GTX Titan) and entry level Maxwell (Nvidia GTX 750) GPUs. The results of this evaluation showed high system performance, limited only by device side IO (600MBps) in all tests. GPF+ maintained high occupancy and device utilisation in all tests, without significant serialisation, and showed improved scaling to more complex filter sets. Results were used to visualise captures of up to 160 GB in seconds, and to extract and pre-filter captures small enough to be easily analysed in applications such as Wireshark.
- Full Text:
- Date Issued: 2016
Gold nanoparticle–based colorimetric probes for dopamine detection
- Authors: Ngomane, Nokuthula
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4565 , http://hdl.handle.net/10962/d1021261
- Description: Colorimetric probes have become important tools in analysis and biomedical technology. This thesis reports on the development of such probes for the detection of dopamine (DA). Liquid and different solid state probes were developed utilizing un–functionalized gold nanoparticles (UF–AuNPs). The liquid state probe is based on the growth and aggregation of the UF–AuNPs in the presence of DA. Upon addition of the UF–AuNPs to various concentrations of DA, the shape, size and colour change results in spectral shifts from lower to higher wavelengths. The analyte can be easily monitored by the naked eye from 5.0 nM DA with a calculated limit of detection of 2.5 nM (3σ) under optimal pH. Ascorbic acid (AA) has a potential to interfere with DA detection in solution since it is often present in biological fluids, but in this case the interference was limited to solutions where its concentration was beyond 200 times greater than that of DA. Since most of the previously reported colorimetric probes, especially those for DA are solution based, the main focus of the thesis was in the development of a solid state based colorimetric probe in the form of nanofibre mats. To overcome the interference challenges experienced in the solution studies (the interference by high concentrations of AA), the suitability of molecularly imprinted polymers (MIPs) for the selective detection of DA was investigated. The results showed that the MIPs produced did not play a significant role in enhancing the selectivity towards DA. A probe composed of just the UF–AuNPs and Nylon–6 (UF–AuNPs + N6) was also developed. The UF–AuNPs were synthesized following an in situ reduction method. The probe was only selective to DA and insensitive to other catecholamines at physiological pH. Thus, the probe did not require any addition functionalities to achieve selectivity and sensitive to DA. The liquid state probe and the composite UF–AuNPs + N6 nanofibre probe were successfully applied to a whole blood sample and showed good selectivity towards DA. The simple, sensitive and selective probe could be an excellent alternative for on–site and immediate detection of DA without the use of instrumentation. For quantification of DA using the solid state probe, open–source software imageJ was used to assist in the analysis of the nanofibre colours. It was observed that the intensity of the colour increased with the increase in concentration of DA in a linear fashion. The use of imageJ can also be a great alternative where the colour changes are not so clear or for visually impaired people. The solid state probe developed can detect DA qualitatively and quantitatively. The work also forms a good foundation for development of such probes for other analyte.
- Full Text:
- Date Issued: 2016
- Authors: Ngomane, Nokuthula
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4565 , http://hdl.handle.net/10962/d1021261
- Description: Colorimetric probes have become important tools in analysis and biomedical technology. This thesis reports on the development of such probes for the detection of dopamine (DA). Liquid and different solid state probes were developed utilizing un–functionalized gold nanoparticles (UF–AuNPs). The liquid state probe is based on the growth and aggregation of the UF–AuNPs in the presence of DA. Upon addition of the UF–AuNPs to various concentrations of DA, the shape, size and colour change results in spectral shifts from lower to higher wavelengths. The analyte can be easily monitored by the naked eye from 5.0 nM DA with a calculated limit of detection of 2.5 nM (3σ) under optimal pH. Ascorbic acid (AA) has a potential to interfere with DA detection in solution since it is often present in biological fluids, but in this case the interference was limited to solutions where its concentration was beyond 200 times greater than that of DA. Since most of the previously reported colorimetric probes, especially those for DA are solution based, the main focus of the thesis was in the development of a solid state based colorimetric probe in the form of nanofibre mats. To overcome the interference challenges experienced in the solution studies (the interference by high concentrations of AA), the suitability of molecularly imprinted polymers (MIPs) for the selective detection of DA was investigated. The results showed that the MIPs produced did not play a significant role in enhancing the selectivity towards DA. A probe composed of just the UF–AuNPs and Nylon–6 (UF–AuNPs + N6) was also developed. The UF–AuNPs were synthesized following an in situ reduction method. The probe was only selective to DA and insensitive to other catecholamines at physiological pH. Thus, the probe did not require any addition functionalities to achieve selectivity and sensitive to DA. The liquid state probe and the composite UF–AuNPs + N6 nanofibre probe were successfully applied to a whole blood sample and showed good selectivity towards DA. The simple, sensitive and selective probe could be an excellent alternative for on–site and immediate detection of DA without the use of instrumentation. For quantification of DA using the solid state probe, open–source software imageJ was used to assist in the analysis of the nanofibre colours. It was observed that the intensity of the colour increased with the increase in concentration of DA in a linear fashion. The use of imageJ can also be a great alternative where the colour changes are not so clear or for visually impaired people. The solid state probe developed can detect DA qualitatively and quantitatively. The work also forms a good foundation for development of such probes for other analyte.
- Full Text:
- Date Issued: 2016
Financial characteristics of the nonprofit organisation: theory and evidence for the assessment of the financial condition of South African public universities
- Authors: Bunting, Mark Bevan
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:923 , http://hdl.handle.net/10962/d1021298 , http://orcid.org/0000-0002-3392-554X
- Description: In this thesis, an analytical framework is developed for the assessment of the financial condition of South African public universities. Foundational constructs of nonprofit economics are applied in the consideration of financial theories of nonprofit organisations in general, and public universities in particular. From this review, a number of hypotheses are developed. Each of these specifies a positive or negative association between a university's financial condition and a particular dimension of its assets, liabilities, equity, revenues, expenses and surplus. From the nonprofit financial analysis literature, ratios and indicators relevant to these hypotheses are selected. Audited data from the annual financial statements of the universities for the seven year period 2007 to 2013 are substantially transformed in mitigation of failures in accounting, auditing and accountability. The adjusted accounting numbers are used to calculate the financial indicators applicable to each university. Exploratory factor analysis is implemented to categorise and organise this large indicator set on the basis of identified associations with a smaller number of factors. It is found that the financial condition of South African public universities is defined by two broad financial characteristics, capital and revenue. Assessment of the capital dimension is informed by a focus on institutional equity, with particular emphasis on expendable equity and its proportionate relationships with surplus, total capital, and total expenses. The revenue dimension is appropriately evaluated in the context of a comparative and interactive consideration of the three main components of South African public university revenue, as well as the proportionate relationship between non-staff operating expenses and total expenses. The framework displays considerable levels of stability and consistency over the seven year review period, and its constructs are, in addition, robust to the application of multiple alternative confirmatory tests involving financial data that are independent of the factor solutions. The financial condition assessment framework developed in this thesis offers a contribution to a broader discourse in nonprofit finance and accounting, with a focus on public university finances.
- Full Text:
- Date Issued: 2016
- Authors: Bunting, Mark Bevan
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:923 , http://hdl.handle.net/10962/d1021298 , http://orcid.org/0000-0002-3392-554X
- Description: In this thesis, an analytical framework is developed for the assessment of the financial condition of South African public universities. Foundational constructs of nonprofit economics are applied in the consideration of financial theories of nonprofit organisations in general, and public universities in particular. From this review, a number of hypotheses are developed. Each of these specifies a positive or negative association between a university's financial condition and a particular dimension of its assets, liabilities, equity, revenues, expenses and surplus. From the nonprofit financial analysis literature, ratios and indicators relevant to these hypotheses are selected. Audited data from the annual financial statements of the universities for the seven year period 2007 to 2013 are substantially transformed in mitigation of failures in accounting, auditing and accountability. The adjusted accounting numbers are used to calculate the financial indicators applicable to each university. Exploratory factor analysis is implemented to categorise and organise this large indicator set on the basis of identified associations with a smaller number of factors. It is found that the financial condition of South African public universities is defined by two broad financial characteristics, capital and revenue. Assessment of the capital dimension is informed by a focus on institutional equity, with particular emphasis on expendable equity and its proportionate relationships with surplus, total capital, and total expenses. The revenue dimension is appropriately evaluated in the context of a comparative and interactive consideration of the three main components of South African public university revenue, as well as the proportionate relationship between non-staff operating expenses and total expenses. The framework displays considerable levels of stability and consistency over the seven year review period, and its constructs are, in addition, robust to the application of multiple alternative confirmatory tests involving financial data that are independent of the factor solutions. The financial condition assessment framework developed in this thesis offers a contribution to a broader discourse in nonprofit finance and accounting, with a focus on public university finances.
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- Date Issued: 2016