Thermal tolerance and the potential effects of climate change on coastal intertidal and estuarine organisms in the Kariega Estuary and adjacent intertitdal coastline, Eastern Cape, South Africa
- Authors: Van der Walt, Kerry-Ann
- Date: 2020
- Subjects: Ectotherms -- Climatic factors , Ectotherms -- Effect of temperature on , Fishes -- Climatic factors , Fishes -- Effect of temperature on , Climatic changes -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/148459 , vital:38741
- Description: Temperature changes due to the effects of climate change are evident on all continents and oceans. As a result, there is a growing concern over how marine ectotherms will respond to extreme or fluctuating environmental temperatures. Temperature changes have strong direct and indirect effects on individual, population, and ecosystem functioning traits. A multi-scale approach determining the thermal tolerance and performance of several marine ectotherms belonging to different coastal habitats is rarely considered in thermal physiology studies but is effective for an integrated ecosystem assessment. As such, for this thesis, I aimed to quantify and compare the thermal tolerance and performance of a range of coastal marine ectotherms (fish and macro-invertebrates) with different biogeographical distributions from estuarine, subtidal and rocky intertidal habitats to available and projected in situ temperature data. This was also undertaken to gauge the local vulnerability of each species across summer and winter in a warm-temperate region of South Africa. This was done using a multi-method physiological approach, which included the dynamic method (CTmax and CTmin), static respirometry and maximum heart rate fHmax). Results of the dynamic method on several fish and macro-invertebrate species indicated that there are differences in thermal tolerance according to taxonomy, biogeography and habitat for both summer and winter. Macro-invertebrate species generally had higher CTmax endpoints, lower CTmin endpoints, higher upper and lower breadths in tolerance, higher upper and lower thermal safety margins and higher thermal scopes than the fish species. This could be a result of the macro-invertebrate species studied being less mobile compared with fish species (which are able to move to more favourable conditions) as well as having broader geographical distributions. In addition, macro-invertebrates from the intertidal rock pool habitat (Palaemon peringueyi; Pernaperna) were more tolerant of high and low temperatures compared with the macro-invertebrates from the estuarine habitat (Clibanarius virescens; Parasesarma catenatum; Upogebia africana). Overall, macro-invertebrates, with the exception of Parechinus angulosus, investigated in this study indicated that current temperatures and projected climate change scenarios across seasons would not have a significant impact on them and that they are highly adaptable to changing temperature regimes. This sign of high tolerance was further supported by the heart rates of P. perna and P. catenatum under an acute increase in temperature (1.0 °C.h-1) which showed individuals of each species physiologically depressing their metabolism until a final Arrhenius breakpoint temperature was reached (TAB). Among the fish species investigated in this study, tropical species (Chaetodon marleyi; Kuhlia mugil) had the highest CTmax and CTmin endpoints when compared with the temperate (Diplodus capensis; Sarpa salpa), warm-water endemic (Chelon dumerili; Rhabdosargus holubi) and cool-water endemic (Chelon richardsonii) fishes. This suggests that due to their lower breadths in tolerance and thermal safety margins being small, tropical species may be less tolerant of cold temperatures and thermal variability, especially in the form of summer upwelling events which are expected to increase in intensity and frequency in this region as a result of anthropogenic climate change effects. On the other hand, however, if a temperature increase of 2.0 - 4.0 °C takes place at the end of the century as predicted by the Intergovernmental Panel on Climate Change (IPCC), it is likely that tropical species such as C. marleyi will become more common. Temperate species such as D. capensis and S. salpa were able to tolerate a wide range of temperatures (wide thermal scope) compared with the other fish species. These findings may suggest that D. capensis and S. salpa are thermally resilient and may be the least vulnerable to climate change effects and temperature variability. When evaluating the different life stages of D. capensis, however, using the dynamic method (juveniles and adults), static respirometry (juveniles) and maximum heart rate (adults), results suggested that juveniles of this temperate species will be more resilient to increases in ocean temperatures compared with the adults because they have a higher thermal tolerance (CTmax/TCRIT) and a greater metabolic scope (TOPT) at higher temperatures. For both juveniles and adults, temperatures beyond 28.0 °C (upper Tpej; Tarr) will have a significant impact on their physiology. Using a multi-scale and multi-method approach thus helped to identify which species or community may be vulnerable to the effects of climate change within shallow coastal environments in this warm-temperate climate change hotspot. Adopting this type of approach will assist policy makers in developing comprehensive climate change management frameworks for coastal ecosystems globally and around South Africa.
- Full Text:
- Authors: Van der Walt, Kerry-Ann
- Date: 2020
- Subjects: Ectotherms -- Climatic factors , Ectotherms -- Effect of temperature on , Fishes -- Climatic factors , Fishes -- Effect of temperature on , Climatic changes -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/148459 , vital:38741
- Description: Temperature changes due to the effects of climate change are evident on all continents and oceans. As a result, there is a growing concern over how marine ectotherms will respond to extreme or fluctuating environmental temperatures. Temperature changes have strong direct and indirect effects on individual, population, and ecosystem functioning traits. A multi-scale approach determining the thermal tolerance and performance of several marine ectotherms belonging to different coastal habitats is rarely considered in thermal physiology studies but is effective for an integrated ecosystem assessment. As such, for this thesis, I aimed to quantify and compare the thermal tolerance and performance of a range of coastal marine ectotherms (fish and macro-invertebrates) with different biogeographical distributions from estuarine, subtidal and rocky intertidal habitats to available and projected in situ temperature data. This was also undertaken to gauge the local vulnerability of each species across summer and winter in a warm-temperate region of South Africa. This was done using a multi-method physiological approach, which included the dynamic method (CTmax and CTmin), static respirometry and maximum heart rate fHmax). Results of the dynamic method on several fish and macro-invertebrate species indicated that there are differences in thermal tolerance according to taxonomy, biogeography and habitat for both summer and winter. Macro-invertebrate species generally had higher CTmax endpoints, lower CTmin endpoints, higher upper and lower breadths in tolerance, higher upper and lower thermal safety margins and higher thermal scopes than the fish species. This could be a result of the macro-invertebrate species studied being less mobile compared with fish species (which are able to move to more favourable conditions) as well as having broader geographical distributions. In addition, macro-invertebrates from the intertidal rock pool habitat (Palaemon peringueyi; Pernaperna) were more tolerant of high and low temperatures compared with the macro-invertebrates from the estuarine habitat (Clibanarius virescens; Parasesarma catenatum; Upogebia africana). Overall, macro-invertebrates, with the exception of Parechinus angulosus, investigated in this study indicated that current temperatures and projected climate change scenarios across seasons would not have a significant impact on them and that they are highly adaptable to changing temperature regimes. This sign of high tolerance was further supported by the heart rates of P. perna and P. catenatum under an acute increase in temperature (1.0 °C.h-1) which showed individuals of each species physiologically depressing their metabolism until a final Arrhenius breakpoint temperature was reached (TAB). Among the fish species investigated in this study, tropical species (Chaetodon marleyi; Kuhlia mugil) had the highest CTmax and CTmin endpoints when compared with the temperate (Diplodus capensis; Sarpa salpa), warm-water endemic (Chelon dumerili; Rhabdosargus holubi) and cool-water endemic (Chelon richardsonii) fishes. This suggests that due to their lower breadths in tolerance and thermal safety margins being small, tropical species may be less tolerant of cold temperatures and thermal variability, especially in the form of summer upwelling events which are expected to increase in intensity and frequency in this region as a result of anthropogenic climate change effects. On the other hand, however, if a temperature increase of 2.0 - 4.0 °C takes place at the end of the century as predicted by the Intergovernmental Panel on Climate Change (IPCC), it is likely that tropical species such as C. marleyi will become more common. Temperate species such as D. capensis and S. salpa were able to tolerate a wide range of temperatures (wide thermal scope) compared with the other fish species. These findings may suggest that D. capensis and S. salpa are thermally resilient and may be the least vulnerable to climate change effects and temperature variability. When evaluating the different life stages of D. capensis, however, using the dynamic method (juveniles and adults), static respirometry (juveniles) and maximum heart rate (adults), results suggested that juveniles of this temperate species will be more resilient to increases in ocean temperatures compared with the adults because they have a higher thermal tolerance (CTmax/TCRIT) and a greater metabolic scope (TOPT) at higher temperatures. For both juveniles and adults, temperatures beyond 28.0 °C (upper Tpej; Tarr) will have a significant impact on their physiology. Using a multi-scale and multi-method approach thus helped to identify which species or community may be vulnerable to the effects of climate change within shallow coastal environments in this warm-temperate climate change hotspot. Adopting this type of approach will assist policy makers in developing comprehensive climate change management frameworks for coastal ecosystems globally and around South Africa.
- Full Text:
The incidence of musculoskeletal disorders and stakeholder perceptions of work challenges in South-Eastern Nigerian quarry mining industry
- Authors: Egwuonwu, Victor Afamerfuna
- Date: 2020
- Subjects: Quarries and quarrying -- Health aspects -- Nigeria , Musculoskeletal system -- Diseases -- Nigeria , Miners -- Health and hygiene -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141263 , vital:37957
- Description: Musculoskeletal disorders (MSDs) are very common among industrial labourers, leading to sick leave absence, disability and low productivity at work. MSDs have multifactorial causes, thereby making it difficult to pinpoint the extent of the contributions of the various risks regarding the mechanism of its pathophysiology. Previously, attempts were made to study regional pain symptoms in varying occupational groups, disregarding the particularities of the different workplace situations. It is important to highlight, that quantifying physical exposure factors that contribute to MSDs occurrence using quantitative approach alone could be inadequate. It is therefore imperative to incorporate qualitative approach to unmask accompanying psychosocial stressors, which are mostly explanatory variables. The study investigated the following: 12-month retrospective prevalence of MSDs, prospective incidence, risk factors and pattern of MSDs in a 6-month follow-up survey of selected quarry mineworkers, who reported MSDs complaints at the mine clinic. The study also determined the level of psychosocial stress associated with working in the mine by understanding stakeholders’ perception of work challenges, and how it influenced recurrence of MSDs. The study utilised a mixed method design with two phases: phase 1 was an initial baseline retrospective prevalence and a prospective cohort-control incidence survey. The Cultural and Psychosocial Influence on Disability (CUPID) questionnaire was translated into an Igbo-language version, cross-culturally adapted and utilized. The instrument was administered via oral interview and sought information on the following: demographic characteristics; pain in different anatomical sites and associated disability for tasks of daily living; as well as information on any change of job and reason during the study period, recent pain in different anatomical sites and associated disability for tasks of daily living; distress from common somatic symptoms; mental health status, sickness absence in the past 5-months for musculoskeletal pain. Phase 2 was a qualitative focus group discussion that engaged mine stakeholders on their perceptions of work challenges. Descriptive statistics of mean and standard deviation was utilised to analyse sociodemographic characteristics of participants. MSD incidence rates were estimated and the patterns of MSD incidence at different anatomical sites were also determined. The Cox proportional regression analyses were utilised to compare hazard ratios of MSD risks between the exposed cohorts and unexposed cohorts in the phase one incidence survey, alpha level was set at 0.05. Transcription, thematic and content analyses with the aid of Nvivo version 11 for windows was used to interpret stakeholders’ perception of work challenges. The incidence of MSD was 6.2 per 1000, with shoulder pain being the most reported complaint (40% prevalence). This was followed by back pain with the distribution of back pain presented as follows: upper back (20.37%), lower back (45.50%) and both (34.13%). All participants reported previous medical history of back, shoulder and neck pain. The relative risk ratio of mineworkers to MSDs was 4.57, which implies that the mineworkers were approximately 5 times more at risk of developing MSDs compared to the recruited unexposed cohorts. Meanwhile, wrist pain (43.58%) was the highest MSD complaints which lead miners to be absent from work, followed by knee and back with 35.42% and 21% respectively. Physical job risks, such as III working underground and squatting or kneeling at work were all significantly associated with MSDs recurrence in all six body parts (HR: 1.12-1.92, 95%CI). Similarly, time pressure to complete task, low decision latitude, poor job satisfaction, somatisation and mental disorder, job insecurity, poor incentive system (HR: 1.01-1.75, 95%CI) were perceived by stakeholders’ and participants alike in the study to be significantly associated with MSDs incidence. Quarrymen are exposed to high MSD risks associated with elevated psychosocial stress from their difficult work situations. The South Eastern Nigerian mine stakeholders believed that the high incidence of MSDs may have a substantial impact on health and productivity in the near future. Necessitating a clear need for the promotion of stakeholder’s engagement concerning safe work policy implementation initiatives in the sector.
- Full Text:
- Authors: Egwuonwu, Victor Afamerfuna
- Date: 2020
- Subjects: Quarries and quarrying -- Health aspects -- Nigeria , Musculoskeletal system -- Diseases -- Nigeria , Miners -- Health and hygiene -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141263 , vital:37957
- Description: Musculoskeletal disorders (MSDs) are very common among industrial labourers, leading to sick leave absence, disability and low productivity at work. MSDs have multifactorial causes, thereby making it difficult to pinpoint the extent of the contributions of the various risks regarding the mechanism of its pathophysiology. Previously, attempts were made to study regional pain symptoms in varying occupational groups, disregarding the particularities of the different workplace situations. It is important to highlight, that quantifying physical exposure factors that contribute to MSDs occurrence using quantitative approach alone could be inadequate. It is therefore imperative to incorporate qualitative approach to unmask accompanying psychosocial stressors, which are mostly explanatory variables. The study investigated the following: 12-month retrospective prevalence of MSDs, prospective incidence, risk factors and pattern of MSDs in a 6-month follow-up survey of selected quarry mineworkers, who reported MSDs complaints at the mine clinic. The study also determined the level of psychosocial stress associated with working in the mine by understanding stakeholders’ perception of work challenges, and how it influenced recurrence of MSDs. The study utilised a mixed method design with two phases: phase 1 was an initial baseline retrospective prevalence and a prospective cohort-control incidence survey. The Cultural and Psychosocial Influence on Disability (CUPID) questionnaire was translated into an Igbo-language version, cross-culturally adapted and utilized. The instrument was administered via oral interview and sought information on the following: demographic characteristics; pain in different anatomical sites and associated disability for tasks of daily living; as well as information on any change of job and reason during the study period, recent pain in different anatomical sites and associated disability for tasks of daily living; distress from common somatic symptoms; mental health status, sickness absence in the past 5-months for musculoskeletal pain. Phase 2 was a qualitative focus group discussion that engaged mine stakeholders on their perceptions of work challenges. Descriptive statistics of mean and standard deviation was utilised to analyse sociodemographic characteristics of participants. MSD incidence rates were estimated and the patterns of MSD incidence at different anatomical sites were also determined. The Cox proportional regression analyses were utilised to compare hazard ratios of MSD risks between the exposed cohorts and unexposed cohorts in the phase one incidence survey, alpha level was set at 0.05. Transcription, thematic and content analyses with the aid of Nvivo version 11 for windows was used to interpret stakeholders’ perception of work challenges. The incidence of MSD was 6.2 per 1000, with shoulder pain being the most reported complaint (40% prevalence). This was followed by back pain with the distribution of back pain presented as follows: upper back (20.37%), lower back (45.50%) and both (34.13%). All participants reported previous medical history of back, shoulder and neck pain. The relative risk ratio of mineworkers to MSDs was 4.57, which implies that the mineworkers were approximately 5 times more at risk of developing MSDs compared to the recruited unexposed cohorts. Meanwhile, wrist pain (43.58%) was the highest MSD complaints which lead miners to be absent from work, followed by knee and back with 35.42% and 21% respectively. Physical job risks, such as III working underground and squatting or kneeling at work were all significantly associated with MSDs recurrence in all six body parts (HR: 1.12-1.92, 95%CI). Similarly, time pressure to complete task, low decision latitude, poor job satisfaction, somatisation and mental disorder, job insecurity, poor incentive system (HR: 1.01-1.75, 95%CI) were perceived by stakeholders’ and participants alike in the study to be significantly associated with MSDs incidence. Quarrymen are exposed to high MSD risks associated with elevated psychosocial stress from their difficult work situations. The South Eastern Nigerian mine stakeholders believed that the high incidence of MSDs may have a substantial impact on health and productivity in the near future. Necessitating a clear need for the promotion of stakeholder’s engagement concerning safe work policy implementation initiatives in the sector.
- Full Text:
Microbial fuel cells for remediation of metal rich wastewater coupled with bioelectricity generation
- Authors: Mshoperi, Edith
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124112 , vital:35540
- Description: Expected release date-April 2022
- Full Text: false
Microbial fuel cells for remediation of metal rich wastewater coupled with bioelectricity generation
- Authors: Mshoperi, Edith
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124112 , vital:35540
- Description: Expected release date-April 2022
- Full Text: false
Formulation, development and assessment of devil’s claw loaded phyto-elastosomes in thermo-responsive hydrogels
- Authors: Ntemi, Pascal Vitalis
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164568 , vital:41139 , doi:10.21504/10962/164568
- Description: Thesis (PhD)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Authors: Ntemi, Pascal Vitalis
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164568 , vital:41139 , doi:10.21504/10962/164568
- Description: Thesis (PhD)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
The role of the Hop co-chaperone in the formation of Hsp90 complexes: chaperone link to glycolysis
- Authors: Maharaj, Shantal
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163593 , vital:41051 , doi:10.21504/10962/163593
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Authors: Maharaj, Shantal
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163593 , vital:41051 , doi:10.21504/10962/163593
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
A classification of large wetlands in Africa’s elevated drylands based on their formation, structure, and hydrological functioning using Earth Observation (EO) data and Geographic Information System (GIS)
- Authors: Lidzhegu, Zwidofhelangani
- Date: 2020
- Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142668 , vital:38100
- Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
- Full Text:
- Authors: Lidzhegu, Zwidofhelangani
- Date: 2020
- Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142668 , vital:38100
- Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
- Full Text:
An investigation into the nature and adequacy of tax compliance tools available to assist small businesses in the state of Oklahoma in the United States of America
- Authors: Cary, Cindi L
- Date: 2020
- Subjects: Tax administration and procedure -- United States , United States. Internal Revenue Service , Small business -- Oklahoma , Small business -- United States , Taxpayer compliance -- Oklahoma , Taxpayer compliance -- United States
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141015 , vital:37937
- Description: This study identifies and analyses the effectiveness of the tax tools available to the small businesses that make up more than 99 per cent of all businesses in the United States and the state of Oklahoma through an extensive investigation of the small business resources offered by federal and state government agencies, higher education institutions and the professional accounting community. The study uses numerous measurements in order to acquire multiple perspectives and relies on the examination of government websites and documents, interviews, experiments, surveys, and questionnaires to determine the existing small business tax tools and their limitations. The research offers an in-depth analysis of the facts and limitations of the small business services offered by the Internal Revenue Service (IRS). The IRS is determined the largest source of small business tax tools, but limitations plague their effectiveness. Higher education is found guilty of not providing small business education in business or accounting disciplines, leaving college graduates ill-prepared to assist small businesses. Higher education is urged to implement a small business accounting curriculum that couples field experience with classroom lectures and textbooks. This study finds the accounting profession apathetic with regard to informing small businesses of accounting services and presses certified public accountants to be more involved in the education of future small business accountants. The study concludes with recommendations to reduce the small business tax burden by improving the existing small business tax tools.
- Full Text:
- Authors: Cary, Cindi L
- Date: 2020
- Subjects: Tax administration and procedure -- United States , United States. Internal Revenue Service , Small business -- Oklahoma , Small business -- United States , Taxpayer compliance -- Oklahoma , Taxpayer compliance -- United States
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141015 , vital:37937
- Description: This study identifies and analyses the effectiveness of the tax tools available to the small businesses that make up more than 99 per cent of all businesses in the United States and the state of Oklahoma through an extensive investigation of the small business resources offered by federal and state government agencies, higher education institutions and the professional accounting community. The study uses numerous measurements in order to acquire multiple perspectives and relies on the examination of government websites and documents, interviews, experiments, surveys, and questionnaires to determine the existing small business tax tools and their limitations. The research offers an in-depth analysis of the facts and limitations of the small business services offered by the Internal Revenue Service (IRS). The IRS is determined the largest source of small business tax tools, but limitations plague their effectiveness. Higher education is found guilty of not providing small business education in business or accounting disciplines, leaving college graduates ill-prepared to assist small businesses. Higher education is urged to implement a small business accounting curriculum that couples field experience with classroom lectures and textbooks. This study finds the accounting profession apathetic with regard to informing small businesses of accounting services and presses certified public accountants to be more involved in the education of future small business accountants. The study concludes with recommendations to reduce the small business tax burden by improving the existing small business tax tools.
- Full Text:
Quantifying ecosystem restoration recovery and restoration practice following the biological control of invasive alien macrophytes in Southern Africa
- Authors: Motitsoe, Samuel Nkopane
- Date: 2020
- Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167519 , vital:41488
- Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
- Full Text:
- Authors: Motitsoe, Samuel Nkopane
- Date: 2020
- Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167519 , vital:41488
- Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
- Full Text:
Non-marital fertility in South Africa: trends, determinants and implications
- Authors: Kara, Reesha
- Date: 2020
- Subjects: Fertility, Human -- South Africa , Child rearing -- South Africa , Parenting -- South Africa , Motherhood -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165620 , vital:41264
- Description: Background: Non-martial fertility is traditionally associated with teenage pregnancy however international and South African literature has detailed increases in the number of adult women who are having children outside of a marriage. South African literature on non-marital fertility is sparse as it lacks a national overview of the trends and determinants of non-marital fertility among women aged 30 and older. The aim of this study was to present a national overview of non-marital fertility among women aged 30 and older. South African’s attitudes to and opinions of non-marital fertility were also investigated, and the lived realities of older mothers were explored. Methods: A mixed-methods research design was employed where the General Household Survey, National Income Dynamics Study and the South African Social Attitudes Survey were the main data sources. Using these data sets, descriptive and inferential statistics were computed using Stata. Using purposive and snowball sampling, four never-married older mothers (NMOMs) from KwaZulu-Natal (Durban) were identified as research participants. The in-depth life histories of these women were collected through face-to- face semi-structured interviews. Results: The results show an 18.43% increase in never-married mothers aged 15- 49 between 2002 and 2017 and interestingly, this increase is not necessarily driven by older mothers (30-49). NMOMs belonged to households with a lower average per capita total monthly household income (R1873.91) compared to all mothers aged 30-49 (R3428.76). NMOMs were also more likely to live in female-headed households (89.52%), to be household heads (64.22%) and to live in traditional areas (35.72%). Between 2002 and 2017, there was a 76.76% increase in mothers (aged 30-49) who were never married and a 7.74% decrease in those who were married, indicating a change in the marital profile of mothers. Despite this national increase in non-marital fertility, South African’s believe that premarital sexual activity is wrong, and that childbearing should take place within a marriage. Similar sentiments were echoed in the in-depth life histories as being the sole breadwinner and primary caregiver, the research participants experienced challenges as single mothers. Conclusion and recommendations: The study has found that there has been an increase in non-marital fertility in South Africa between 2002 and 2017 and that there is an economic element to non-marital fertility in the country. Additional research into non-marital fertility at a national level is recommended with a focus on all women aged 15-49.
- Full Text:
- Authors: Kara, Reesha
- Date: 2020
- Subjects: Fertility, Human -- South Africa , Child rearing -- South Africa , Parenting -- South Africa , Motherhood -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165620 , vital:41264
- Description: Background: Non-martial fertility is traditionally associated with teenage pregnancy however international and South African literature has detailed increases in the number of adult women who are having children outside of a marriage. South African literature on non-marital fertility is sparse as it lacks a national overview of the trends and determinants of non-marital fertility among women aged 30 and older. The aim of this study was to present a national overview of non-marital fertility among women aged 30 and older. South African’s attitudes to and opinions of non-marital fertility were also investigated, and the lived realities of older mothers were explored. Methods: A mixed-methods research design was employed where the General Household Survey, National Income Dynamics Study and the South African Social Attitudes Survey were the main data sources. Using these data sets, descriptive and inferential statistics were computed using Stata. Using purposive and snowball sampling, four never-married older mothers (NMOMs) from KwaZulu-Natal (Durban) were identified as research participants. The in-depth life histories of these women were collected through face-to- face semi-structured interviews. Results: The results show an 18.43% increase in never-married mothers aged 15- 49 between 2002 and 2017 and interestingly, this increase is not necessarily driven by older mothers (30-49). NMOMs belonged to households with a lower average per capita total monthly household income (R1873.91) compared to all mothers aged 30-49 (R3428.76). NMOMs were also more likely to live in female-headed households (89.52%), to be household heads (64.22%) and to live in traditional areas (35.72%). Between 2002 and 2017, there was a 76.76% increase in mothers (aged 30-49) who were never married and a 7.74% decrease in those who were married, indicating a change in the marital profile of mothers. Despite this national increase in non-marital fertility, South African’s believe that premarital sexual activity is wrong, and that childbearing should take place within a marriage. Similar sentiments were echoed in the in-depth life histories as being the sole breadwinner and primary caregiver, the research participants experienced challenges as single mothers. Conclusion and recommendations: The study has found that there has been an increase in non-marital fertility in South Africa between 2002 and 2017 and that there is an economic element to non-marital fertility in the country. Additional research into non-marital fertility at a national level is recommended with a focus on all women aged 15-49.
- Full Text:
Conserving land for people: transformative adaptive co-management of sustainable protected areas in the eastern Democratic Republic of Congo
- Authors: Kalyongo, Kujirakwinja Deo
- Date: 2020
- Subjects: Protected areas -- Congo (Democratic Republic) , Protected areas -- Government policy -- Congo (Democratic Republic) , Protected areas -- Management -- Congo (Democratic Republic) , Conservation of natural resources -- Congo (Democratic Republic)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165912 , vital:41296
- Description: Conservation practices and approaches in the Democratic Republic of Congo (DRC), as in other parts of the world, have evolved from traditional to fortress and collaborative contemporary approaches such as adaptive co-management. These approaches aim to include multiple decision-makers using diversified resources and, existing formal and informal governance structures. Collaborative approaches also consider conflict resolution and external factors that can influence conservation outputs and outcomes. In the DRC context, conflicts over resources are related not only to resource access and power but also to the ineffectiveness of collaborative approaches that exclude stakeholders such as local communities. These conflicts have negatively affected protected areas and weakened the management and governance of protected areas. Therefore, evolving approaches such as adaptive co-management that consider power relations, the multi-scaled involvement of actors and learning loops to adjust strategies are seen as better options to improve the governance of protected areas and minimise the degradation of key ecosystems. My research explored the gazettement processes of three protected areas in the eastern DRC (Itombwe, Kabobo and Okapi Reserves). I focused on the influence of social-political, historical and psychological factors on the management and governance of protected areas in the DRC. In addition, the research reveals the inclusive gazettement processes of protected areas is the foundation of successful co-management approaches. I found that values and good governance practices play a key role in influencing local perceptions and support to conservation interventions. Whilst some conservation practitioners believe that economic benefits to communities are the most predominant motivating factor, I found that good conservation management practices can motivate communities to support protected area management. Bad management practices were related not only to inadequate conservation approaches and practices but also to factors such as corruption, inadequate law enforcement and the inappropriate equipment of rangers. Therefore, I suggest that long term protected area management in DRC should consider how the value of resources for communities and protected areas have been changing throughout the history of conservation, and how to best share power and responsibilities with local resource users and stakeholders. This is only possible if conservation practices and approaches, governance process and institutions are transformed at multiple levels.
- Full Text:
- Authors: Kalyongo, Kujirakwinja Deo
- Date: 2020
- Subjects: Protected areas -- Congo (Democratic Republic) , Protected areas -- Government policy -- Congo (Democratic Republic) , Protected areas -- Management -- Congo (Democratic Republic) , Conservation of natural resources -- Congo (Democratic Republic)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/165912 , vital:41296
- Description: Conservation practices and approaches in the Democratic Republic of Congo (DRC), as in other parts of the world, have evolved from traditional to fortress and collaborative contemporary approaches such as adaptive co-management. These approaches aim to include multiple decision-makers using diversified resources and, existing formal and informal governance structures. Collaborative approaches also consider conflict resolution and external factors that can influence conservation outputs and outcomes. In the DRC context, conflicts over resources are related not only to resource access and power but also to the ineffectiveness of collaborative approaches that exclude stakeholders such as local communities. These conflicts have negatively affected protected areas and weakened the management and governance of protected areas. Therefore, evolving approaches such as adaptive co-management that consider power relations, the multi-scaled involvement of actors and learning loops to adjust strategies are seen as better options to improve the governance of protected areas and minimise the degradation of key ecosystems. My research explored the gazettement processes of three protected areas in the eastern DRC (Itombwe, Kabobo and Okapi Reserves). I focused on the influence of social-political, historical and psychological factors on the management and governance of protected areas in the DRC. In addition, the research reveals the inclusive gazettement processes of protected areas is the foundation of successful co-management approaches. I found that values and good governance practices play a key role in influencing local perceptions and support to conservation interventions. Whilst some conservation practitioners believe that economic benefits to communities are the most predominant motivating factor, I found that good conservation management practices can motivate communities to support protected area management. Bad management practices were related not only to inadequate conservation approaches and practices but also to factors such as corruption, inadequate law enforcement and the inappropriate equipment of rangers. Therefore, I suggest that long term protected area management in DRC should consider how the value of resources for communities and protected areas have been changing throughout the history of conservation, and how to best share power and responsibilities with local resource users and stakeholders. This is only possible if conservation practices and approaches, governance process and institutions are transformed at multiple levels.
- Full Text:
Post-apartheid nostalgia and the future of the black visual archive
- Nsele, Zamansele Nsikakazi Busisiwe
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
Urbanisation, foraging and household food security in urban South Africa
- Authors: Garekae, Hesekia
- Date: 2020
- Subjects: Food sovereignty -- South Africa , Food security -- South Africa , Urban density -- South Africa , Urban agriculture -- Law and legislation -- South Africa , Sustainable urban development -- South Africa , Urban ecology (Sociology) -- South Africa , Nutrition surveys -- South Africa -- Potchefstroom , Nutrition surveys -- South Africa -- Thabazimbi , Wild plants, Edible -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167054 , vital:41433
- Description: Over the past several decades, the world’s population has been rapidly urbanising, which has resulted in a marked shift of global population from rural to urban areas. About half of the global population now reside in urban areas and is projected to increase to two-thirds by the year 2050. However, the majority of the future urban population growth is projected to be largely concentrated in Asia and sub-Saharan Africa. Despite the economic prospects normally synonymous with urbanisation, the current speed and scale of urban transformation comes with formidable challenges to contemporary urban society in these two continents. Urbanisation may presents social, economic, health and environmental challenges in urban areas, not least being a shift of the locus of food insecurity from rural to urban areas, leading to poor dietary diversity among many urban dwellers. Similarly, urbanisation alters key ecosystem services and drives habitat alteration and fragmentation, biodiversity loss, proliferation of non-native species and changes on species diversity and richness. The aforementioned changes can result in a deterioration of living conditions and decline on the quality of life for the urban dwellers. However, on the other hand, urban green infrastructure is posed as vital tool in promoting liveable cities and enhancing livelihood resilience. Against this backdrop, this study portrays wild plants, a component of urban green infrastructure, as a key resource in promoting food security and dietary diversity, thereby promoting livelihood resilience and reduced vulnerability, especially of the urban poor. Framed under the ‘right to the city’ approach, this study examined urban foraging practices and their potential contribution to dietary diversity and how they are shaped by and respond to urbanisation in two medium-sized South African towns. The study was conducted in the towns of Potchefstroom and Thabazimbi, South Africa. An explanatory sequential mixed method design was employed for data collection. Multi-stage sampling was employed in selecting the study participants. Firstly, the study towns were stratified into four socio-economic zones: informal, reconstruction and development programme, township and affluent. These zones resemble high density (informal, reconstruction and development programme), medium density (township) and low density (affluent) areas. Then, a total of 374 households were randomly sampled across the socio-economic zones for the main survey (Chapter 3 and 5). A subset of this sample, i.e. 72 participants was considered for dietary recalls, alongside with a random sample of 65 non-foragers (Chapter 4). An inventory of plant species available in a given foraging space was conducted from a total of 136 plots spread across different urban spaces (Chapter 2). Semi-structured interviews were conducted with a total of 81 participants (sub population of the main survey) for elucidating data on urban dynamics (Chapter 6). Lastly, complementary in-depth interviews with 46 participants were conducted. The findings showed that different urban spaces were constituted by diverse vegetation, with 262 distinct plant species encountered across the spaces. The majority (60.7%) were indigenous to South Africa. Species composition and diversity varied with space type, being significantly high in protected areas as compared to the other space types. About half (53%) of the identified plant species had at least one documented use, with medicine, food and firewood being modal, in order of frequency. Species composition and diversity differed between forageable and non-forageable species, being significantly high for forageable species. Urban foraging was widespread, about 68% of the respondents reported foraging. Foraging provided food, fuel energy, medicine, and cultural affirmation, among others. Despite the high prevalence rate of foraging, the study did not find any meaningful contribution of wild foods to overall diets. Nonetheless, wild foods demonstrated a substantial contribution in diversifying diets within particular food groups consumed such as vegetables, thus emerging essential in mitigating monotonous urban diets, particularly of the urban poor. Besides, the prevalence of foraging differed significantly between and within towns, being high for Thabazimbi (54.7%) and residents in the outskirts of town (86.2%) than Potchefstroom (45.3%) and residents in the inner part of town (33.3%). Participation in foraging was primarily a function of childhood (91.8%) exposure and experience with foraging, positive perceptions (79%) towards practice, resident in the outskirts of town (86.2%) and low household income (49.2%). The findings indicated that foraging was driven by multifaceted motivations, with culture (91.8%), health (88.7%), livelihoods needs (75.0%) and leisure (73.8%) being the most common. Vacant spaces (54.7%), riparian areas (30%), and domestic gardens (17.9%) were the most preferred foraging spaces, albeit with differences within towns. Similarly, the mean frequency of access varied with foraging spaces, being slightly high for vacant spaces than riparian areas and domestic gardens. The majority of the respondents were unaware of both formal and informal regulations managing urban landscapes, with those acknowledging some awareness falling short of articulating on the specificities of the regulations. Besides, the findings showed that foraging practice was threatened by urban transformation. Foragers perceived that the practice has changed over time, in terms of spaces, participants and regulations. There was a decreasing trend on the number and size of foraging spaces as well as shifting demographic trends of foragers. Moreover, urban transformation brought about a new set of regulations used for managing certain spaces within the urban landscape. However, some regulations prohibited or restricted access and rights to certain spaces for foraging. Hence, this prompted foragers to devise adaptation strategies to cope with the said changing dynamics. Exploring new foraging sites within and outside forager’s neighbourhoods and negotiating access entry were the most frequently mentioned adaptation strategies. This study contributes to the emerging body of knowledge on urban foraging, which has being seldom understood in the Global South.
- Full Text:
- Authors: Garekae, Hesekia
- Date: 2020
- Subjects: Food sovereignty -- South Africa , Food security -- South Africa , Urban density -- South Africa , Urban agriculture -- Law and legislation -- South Africa , Sustainable urban development -- South Africa , Urban ecology (Sociology) -- South Africa , Nutrition surveys -- South Africa -- Potchefstroom , Nutrition surveys -- South Africa -- Thabazimbi , Wild plants, Edible -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167054 , vital:41433
- Description: Over the past several decades, the world’s population has been rapidly urbanising, which has resulted in a marked shift of global population from rural to urban areas. About half of the global population now reside in urban areas and is projected to increase to two-thirds by the year 2050. However, the majority of the future urban population growth is projected to be largely concentrated in Asia and sub-Saharan Africa. Despite the economic prospects normally synonymous with urbanisation, the current speed and scale of urban transformation comes with formidable challenges to contemporary urban society in these two continents. Urbanisation may presents social, economic, health and environmental challenges in urban areas, not least being a shift of the locus of food insecurity from rural to urban areas, leading to poor dietary diversity among many urban dwellers. Similarly, urbanisation alters key ecosystem services and drives habitat alteration and fragmentation, biodiversity loss, proliferation of non-native species and changes on species diversity and richness. The aforementioned changes can result in a deterioration of living conditions and decline on the quality of life for the urban dwellers. However, on the other hand, urban green infrastructure is posed as vital tool in promoting liveable cities and enhancing livelihood resilience. Against this backdrop, this study portrays wild plants, a component of urban green infrastructure, as a key resource in promoting food security and dietary diversity, thereby promoting livelihood resilience and reduced vulnerability, especially of the urban poor. Framed under the ‘right to the city’ approach, this study examined urban foraging practices and their potential contribution to dietary diversity and how they are shaped by and respond to urbanisation in two medium-sized South African towns. The study was conducted in the towns of Potchefstroom and Thabazimbi, South Africa. An explanatory sequential mixed method design was employed for data collection. Multi-stage sampling was employed in selecting the study participants. Firstly, the study towns were stratified into four socio-economic zones: informal, reconstruction and development programme, township and affluent. These zones resemble high density (informal, reconstruction and development programme), medium density (township) and low density (affluent) areas. Then, a total of 374 households were randomly sampled across the socio-economic zones for the main survey (Chapter 3 and 5). A subset of this sample, i.e. 72 participants was considered for dietary recalls, alongside with a random sample of 65 non-foragers (Chapter 4). An inventory of plant species available in a given foraging space was conducted from a total of 136 plots spread across different urban spaces (Chapter 2). Semi-structured interviews were conducted with a total of 81 participants (sub population of the main survey) for elucidating data on urban dynamics (Chapter 6). Lastly, complementary in-depth interviews with 46 participants were conducted. The findings showed that different urban spaces were constituted by diverse vegetation, with 262 distinct plant species encountered across the spaces. The majority (60.7%) were indigenous to South Africa. Species composition and diversity varied with space type, being significantly high in protected areas as compared to the other space types. About half (53%) of the identified plant species had at least one documented use, with medicine, food and firewood being modal, in order of frequency. Species composition and diversity differed between forageable and non-forageable species, being significantly high for forageable species. Urban foraging was widespread, about 68% of the respondents reported foraging. Foraging provided food, fuel energy, medicine, and cultural affirmation, among others. Despite the high prevalence rate of foraging, the study did not find any meaningful contribution of wild foods to overall diets. Nonetheless, wild foods demonstrated a substantial contribution in diversifying diets within particular food groups consumed such as vegetables, thus emerging essential in mitigating monotonous urban diets, particularly of the urban poor. Besides, the prevalence of foraging differed significantly between and within towns, being high for Thabazimbi (54.7%) and residents in the outskirts of town (86.2%) than Potchefstroom (45.3%) and residents in the inner part of town (33.3%). Participation in foraging was primarily a function of childhood (91.8%) exposure and experience with foraging, positive perceptions (79%) towards practice, resident in the outskirts of town (86.2%) and low household income (49.2%). The findings indicated that foraging was driven by multifaceted motivations, with culture (91.8%), health (88.7%), livelihoods needs (75.0%) and leisure (73.8%) being the most common. Vacant spaces (54.7%), riparian areas (30%), and domestic gardens (17.9%) were the most preferred foraging spaces, albeit with differences within towns. Similarly, the mean frequency of access varied with foraging spaces, being slightly high for vacant spaces than riparian areas and domestic gardens. The majority of the respondents were unaware of both formal and informal regulations managing urban landscapes, with those acknowledging some awareness falling short of articulating on the specificities of the regulations. Besides, the findings showed that foraging practice was threatened by urban transformation. Foragers perceived that the practice has changed over time, in terms of spaces, participants and regulations. There was a decreasing trend on the number and size of foraging spaces as well as shifting demographic trends of foragers. Moreover, urban transformation brought about a new set of regulations used for managing certain spaces within the urban landscape. However, some regulations prohibited or restricted access and rights to certain spaces for foraging. Hence, this prompted foragers to devise adaptation strategies to cope with the said changing dynamics. Exploring new foraging sites within and outside forager’s neighbourhoods and negotiating access entry were the most frequently mentioned adaptation strategies. This study contributes to the emerging body of knowledge on urban foraging, which has being seldom understood in the Global South.
- Full Text:
Mechanism of action of non-synonymous single nucleotide variations associated with α-carbonic anhydrases II, IV and VIII
- Authors: Sanyanga, T. Allan
- Date: 2020
- Subjects: Carbonic anhydrase , Carbonic anhydrase -- Therapeutic use , Nucleotides
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167346 , vital:41470
- Description: The carbonic anhydrase (CA) group of enzymes are Zinc (Zn2+) metalloproteins responsible for the reversible hydration of CO2 to bicarbonate (BCT or HCO− 3 ) and protons (H+) for the facilitation of acid-base balance and homeostasis within the body. Across all organisms, a minimum of six CA families exist, including, α (alpha), β (beta), γ (gamma), δ (delta), η (eta) and ζ (zeta). Some organisms can have more than one family, with exception to humans that contain the α family solely. The α-CA family comprises of 16 isoforms (CA-I to CA-XV) including the CA-VIII, CA-X and CA-XI acatalytic isoforms. Of the catalytic isoforms, CA-II and CA-IV possess one of the fastest rates of reaction, and any disturbances to the function of these enzymes results in CA deficiencies and undesirable phenotypes. CA-II deficiencies result in osteopetrosis with renal tubular acidosis and cerebral calcification, whereas CA-IV deficiencies result in retinitis pigmentosa 17 (RP17). Phenotypic effects generally manifest as a result of poor protein folding and function due to the presence of non-synonymous single nucleotide variations (nsSNVs). Even within the acatalytic isoforms such as CA-VIII that llosterically regulates the affinity of inositol triphosphate (IP3) for the IP3 receptor type 1 (ITPR1) and regulates calcium (Ca2+) signalling, the presence of SNVs also causes phenotypes cerebellar ataxia, mental retardation, and dysequilibrium syndrome 3 (CAMRQ3). Currently the majority of research into the CAs is focused on the inhibition of these proteins to achieve therapeutic effects in patients via the control of HCO− production or reabsorption as observed in glaucoma and diuretic medications. Little research has therefore been devoted into the identification of stabilising or activating compound that could rescue protein function in the case of deficiencies. The main aim of this research was to identify and characterise the effects of nsSNVs on the structure and function of CA-II, CA-IV and CA-VIII to set a foundation for rare disease studies into the CA group of proteins. Combined bioinformatics approaches divided into four main objectives were implemented. These included variant identification, sequence analysis and protein characterisation, force field (FF) parameter generation, molecular dynamics (MD) simulation and dynamic residue network analysis (DRN). Six variants for each of the CA-II, CA-IV and CA-VIII proteins with pathogenic annotations were identified from the HUMA and Ensembl databases. These included the pathogenic variants K18E, K18Q, H107Y, P236H, P236R and N252D for CA-II. CA-IV included the pathogenic R69H, R219C and R219S, and benign N86K, N177K and V234I variants. CA-VIII included pathogenic S100A, S100P, G162R and R237Q, and benign S100L and E109D variants. CA-II has been more extensively studied than CA-IV and CA-VIII, therefore residues essential to its function and stability are known. To discover important residues and regions within the CA-IV and CA-VIII proteins sequence and motif analysis was performed across the α-CA family, using CA-II as a reference. Sequence analysis identified multiple conserved residues between the two acatalytic CA-II and CA-IV, and the acatalytic CA-VIII isoforms that were proposed to be essential for protein stability. With exception to the benign N86K CA-IV variant, none of the other pathogenic or benign CA-II, CA-IV and CA-VIII SNVs were located at functionally or structurally important residues. Motif analysis identified 11 conserved and important motifs within the α-CA family. Several of the identified variants were located on these motifs including K18E, K18Q, H107Y and N252D (CA-II); N86K, R219C, R219S and V234I (CA-IV); and E109D, G162R and R237Q (CA-VIII). As there were no x-ray crystal structures of the variant proteins, homology modelling was performed to calculate the protein structures for characterisation. In CA-VIII, the substitution of Ser for Pro at position 100 (variant S100P) resulted in destruction of the β-sheet that the SNV was located on. Little is known about the mechanism of interaction between CA-VIII and ITPR1, and residues involved. SiteMap and CPORT were used to identify binding site amino for CA-VIII and results identified 38 potential residues. Traditional FFs are incapable of performing MD simulations of metalloproteins. The AMBER ff14SB FF was extended and Zn2+ FF parameters calculated to add support for metalloprotein MD simulations. In the protein, Zn2+ was noted to have a charge less than +1. Variant effects on protein structure were then investigated using MD simulations. Root mean square deviation (RMSD) and radius of gyration (Rg) results indicated subtle SNV effects to the variant global structure in CA-II and CA-IV. However, with regards to CA-VIII RMSD analysis highlighted that variant presence was associated with increases to the structural rigidity of the protein. Principal component analysis (PCA) in conjunction with free energy analysis was performed to observe variant effects on protein conformational sampling in 3D space. The binding of BCT to CA-II induced greater protein conformational sampling and was associated with higher free energy. In CA-IV and CA-VIII PCA analysis revealed key differences in the mechanism of action of pathogenic and benign SNVs. In CA-IV, wild-type (WT) and benign variant protein structures clustered into single low energy well hinting at the presence of more stable structures. Pathogenic variants were associated with higher free energy and proteins sampled more conformations without settling into a low energy well. PCA analysis of CA-VIII indicated the opposite to CA-IV. Pathogenic variants were clustered into low energy wells, while the WT and benign variants showed greater conformational sampling. Dynamic cross correlation (DCC) analysis was performed using the MD-TASK suite to determine variant effects on residue movement. CA-II WT protein revealed that BCT and CO2 were associated with anti-correlated and correlated residue movement, highlighting at opposite mechanisms. In CA-IV and CA-VIII variant presence resulted in a change to residue correlation compared to the WT proteins. DRN analysis was performed to investigate SNV effects of residue accessibility and communication. Results demonstrated that SNVs are associated with allosteric effects on the CA protein structures, and effects are located on the stability assisting residues of the aromatic clusters and the active site of the proteins. CA-II studies discovered that Glu117 is the most important residue for communication, and variant presence results in a decrease to the usage of the residue. This effect was greatest in the CA-II H107Y SNV, and suggests that variants could have an effect on Zn2+ dissociation from the active site. Decreases to the usage of Zn2+ coordinating residues were also noted. Where this occurred, compensatory increases to the usage of other primary and secondary coordination residues were observed, that could possibly assist with the maintenance of Zn2+ within the active site. The CA-IV variants R69H and R219C highlighted potentially similar pathogenic mechanisms, whereas N86K and N177K hinted at potentially similar benign mechanisms. Within CA-VIII, variant presence was associated with changes to the accessibility of the N-terminal binding site residues. The benign CA-VIII variants highlighted possible compensatory mechanisms, whereby as one group of N-terminal residues loses accessibility, there was an increase to the accessibility of other binding site residues to possibly balance the effect. Catalytically, the proton shuttle residue His64 in CA-II was found to occupy a novel conformation named the “faux in” that brought the imidazole group even closer to the Zn2+ compared to the “in” conformation. Overall, compared to traditional MD simulations the incorporation of DRN allowed more detailed investigations into the variant mechanisms of action. This highlights the importance of network analysis in the study of the effects of missense mutations on the structure and function of proteins. Investigations of diseases at the molecular level is essential in the identification of disease pathogenesis and assists with the development of specifically tailored and better treatment options especially in the cases of genetically associated rare diseases.
- Full Text:
- Authors: Sanyanga, T. Allan
- Date: 2020
- Subjects: Carbonic anhydrase , Carbonic anhydrase -- Therapeutic use , Nucleotides
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167346 , vital:41470
- Description: The carbonic anhydrase (CA) group of enzymes are Zinc (Zn2+) metalloproteins responsible for the reversible hydration of CO2 to bicarbonate (BCT or HCO− 3 ) and protons (H+) for the facilitation of acid-base balance and homeostasis within the body. Across all organisms, a minimum of six CA families exist, including, α (alpha), β (beta), γ (gamma), δ (delta), η (eta) and ζ (zeta). Some organisms can have more than one family, with exception to humans that contain the α family solely. The α-CA family comprises of 16 isoforms (CA-I to CA-XV) including the CA-VIII, CA-X and CA-XI acatalytic isoforms. Of the catalytic isoforms, CA-II and CA-IV possess one of the fastest rates of reaction, and any disturbances to the function of these enzymes results in CA deficiencies and undesirable phenotypes. CA-II deficiencies result in osteopetrosis with renal tubular acidosis and cerebral calcification, whereas CA-IV deficiencies result in retinitis pigmentosa 17 (RP17). Phenotypic effects generally manifest as a result of poor protein folding and function due to the presence of non-synonymous single nucleotide variations (nsSNVs). Even within the acatalytic isoforms such as CA-VIII that llosterically regulates the affinity of inositol triphosphate (IP3) for the IP3 receptor type 1 (ITPR1) and regulates calcium (Ca2+) signalling, the presence of SNVs also causes phenotypes cerebellar ataxia, mental retardation, and dysequilibrium syndrome 3 (CAMRQ3). Currently the majority of research into the CAs is focused on the inhibition of these proteins to achieve therapeutic effects in patients via the control of HCO− production or reabsorption as observed in glaucoma and diuretic medications. Little research has therefore been devoted into the identification of stabilising or activating compound that could rescue protein function in the case of deficiencies. The main aim of this research was to identify and characterise the effects of nsSNVs on the structure and function of CA-II, CA-IV and CA-VIII to set a foundation for rare disease studies into the CA group of proteins. Combined bioinformatics approaches divided into four main objectives were implemented. These included variant identification, sequence analysis and protein characterisation, force field (FF) parameter generation, molecular dynamics (MD) simulation and dynamic residue network analysis (DRN). Six variants for each of the CA-II, CA-IV and CA-VIII proteins with pathogenic annotations were identified from the HUMA and Ensembl databases. These included the pathogenic variants K18E, K18Q, H107Y, P236H, P236R and N252D for CA-II. CA-IV included the pathogenic R69H, R219C and R219S, and benign N86K, N177K and V234I variants. CA-VIII included pathogenic S100A, S100P, G162R and R237Q, and benign S100L and E109D variants. CA-II has been more extensively studied than CA-IV and CA-VIII, therefore residues essential to its function and stability are known. To discover important residues and regions within the CA-IV and CA-VIII proteins sequence and motif analysis was performed across the α-CA family, using CA-II as a reference. Sequence analysis identified multiple conserved residues between the two acatalytic CA-II and CA-IV, and the acatalytic CA-VIII isoforms that were proposed to be essential for protein stability. With exception to the benign N86K CA-IV variant, none of the other pathogenic or benign CA-II, CA-IV and CA-VIII SNVs were located at functionally or structurally important residues. Motif analysis identified 11 conserved and important motifs within the α-CA family. Several of the identified variants were located on these motifs including K18E, K18Q, H107Y and N252D (CA-II); N86K, R219C, R219S and V234I (CA-IV); and E109D, G162R and R237Q (CA-VIII). As there were no x-ray crystal structures of the variant proteins, homology modelling was performed to calculate the protein structures for characterisation. In CA-VIII, the substitution of Ser for Pro at position 100 (variant S100P) resulted in destruction of the β-sheet that the SNV was located on. Little is known about the mechanism of interaction between CA-VIII and ITPR1, and residues involved. SiteMap and CPORT were used to identify binding site amino for CA-VIII and results identified 38 potential residues. Traditional FFs are incapable of performing MD simulations of metalloproteins. The AMBER ff14SB FF was extended and Zn2+ FF parameters calculated to add support for metalloprotein MD simulations. In the protein, Zn2+ was noted to have a charge less than +1. Variant effects on protein structure were then investigated using MD simulations. Root mean square deviation (RMSD) and radius of gyration (Rg) results indicated subtle SNV effects to the variant global structure in CA-II and CA-IV. However, with regards to CA-VIII RMSD analysis highlighted that variant presence was associated with increases to the structural rigidity of the protein. Principal component analysis (PCA) in conjunction with free energy analysis was performed to observe variant effects on protein conformational sampling in 3D space. The binding of BCT to CA-II induced greater protein conformational sampling and was associated with higher free energy. In CA-IV and CA-VIII PCA analysis revealed key differences in the mechanism of action of pathogenic and benign SNVs. In CA-IV, wild-type (WT) and benign variant protein structures clustered into single low energy well hinting at the presence of more stable structures. Pathogenic variants were associated with higher free energy and proteins sampled more conformations without settling into a low energy well. PCA analysis of CA-VIII indicated the opposite to CA-IV. Pathogenic variants were clustered into low energy wells, while the WT and benign variants showed greater conformational sampling. Dynamic cross correlation (DCC) analysis was performed using the MD-TASK suite to determine variant effects on residue movement. CA-II WT protein revealed that BCT and CO2 were associated with anti-correlated and correlated residue movement, highlighting at opposite mechanisms. In CA-IV and CA-VIII variant presence resulted in a change to residue correlation compared to the WT proteins. DRN analysis was performed to investigate SNV effects of residue accessibility and communication. Results demonstrated that SNVs are associated with allosteric effects on the CA protein structures, and effects are located on the stability assisting residues of the aromatic clusters and the active site of the proteins. CA-II studies discovered that Glu117 is the most important residue for communication, and variant presence results in a decrease to the usage of the residue. This effect was greatest in the CA-II H107Y SNV, and suggests that variants could have an effect on Zn2+ dissociation from the active site. Decreases to the usage of Zn2+ coordinating residues were also noted. Where this occurred, compensatory increases to the usage of other primary and secondary coordination residues were observed, that could possibly assist with the maintenance of Zn2+ within the active site. The CA-IV variants R69H and R219C highlighted potentially similar pathogenic mechanisms, whereas N86K and N177K hinted at potentially similar benign mechanisms. Within CA-VIII, variant presence was associated with changes to the accessibility of the N-terminal binding site residues. The benign CA-VIII variants highlighted possible compensatory mechanisms, whereby as one group of N-terminal residues loses accessibility, there was an increase to the accessibility of other binding site residues to possibly balance the effect. Catalytically, the proton shuttle residue His64 in CA-II was found to occupy a novel conformation named the “faux in” that brought the imidazole group even closer to the Zn2+ compared to the “in” conformation. Overall, compared to traditional MD simulations the incorporation of DRN allowed more detailed investigations into the variant mechanisms of action. This highlights the importance of network analysis in the study of the effects of missense mutations on the structure and function of proteins. Investigations of diseases at the molecular level is essential in the identification of disease pathogenesis and assists with the development of specifically tailored and better treatment options especially in the cases of genetically associated rare diseases.
- Full Text:
Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
Conceptualisations and pedagogical practices of academic literacy in Namibian higher education
- Authors: Julius, Lukas Homateni
- Date: 2021-04
- Subjects: Information literacy -- Study and teaching (Higher) -- Namibia , Academic writing -- Study and teaching -- Namibia , Qualitative research -- Methodology , Academic language -- Namibia , Information literacy -- Social aspects
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177293 , vital:42807 , 10.21504/10962/177293
- Description: The purpose of this study was to investigate academic literacy development lecturers’ conceptualisations of academic literacy and resultant pedagogical practices in academic development courses at three different Higher Education Institutional types in Namibia. The research sites were a Traditional University, a University of Technology and a Comprehensive University. The focus was to understand the extent to which the academics’ conceptions of academic literacy and the resultant pedagogical practices in the academic development courses at these three Higher Education Institutions (HEIs) facilitate epistemological access into students’ chosen fields of study. Bernstein’s Pedagogical theory (1990), Genre theory (1996) and Halliday’s Systemic Functional Linguistics (1978) were used as the study’s theoretical lenses and analytical framework. An interpretative paradigm and a qualitative case study design were employed as the research approach. Semi-structured interviews, classroom observations and documentary evidence were used to generate data. Research findings revealed a common (mis)conception of the nature of academic literacy, the resultant inadequate learning support offered to students in the selected academic literacy development courses, and a clear divorcing of academic literacy interventions from the students’ ‘home’ or mainstream disciplines at the three HEIs. The participants understood academic literacy from an autonomous position as a set of generic skills which could be taught outside of mainstream classes. Moreover, findings revealed that this understanding impacted on the design and assessments of all the academic literacy courses across the three universities under study. The study calls for a context sensitive model through which academic literacy acquisition can be scaffolded to meet the discipline-specific epistemological needs of the students. , Elalakano lyehokololoningomwa lyomapekapeko ndika olyo okukonakona ehumithokomeho lyomikalo dhokulesha nokushanga meilongngo lyopombada (oAcademic Literaci) maaputudhilongi, okukonakona omafatululo giisimanintsa moAcademic Literaci osho wo okutala iizemo yomikalo dhayooloka dhokulonga noku ilonga iilongwa yayooloka miiputudhilo yelongo lyopombada moNamibia. Omapekapeko ngaka oga li ga ningilwa miiputudhilo yomaukwatya ta ga landula; Oshiputudhiilo shopamudhigululwakalo, Oshiputudhilo shopaunongononi, nOshiputudilo shomailongo gaandjakana. Oshintsa shopokati shomapekapeko ngaka osho okuuva ko ondodo yowino osho wo euveko lyoAcademic Literaci maaputudhilongi nonkene euveko nontseyo ndjika tayi longithwa oku eta oshizemo tashi humitha komeho euveko lyopombanda lyaalongwa yomailongo geewino dhayooloka miiputudhilo itatu yelongo lyopombanda; shino otashi kwathele aalongwa yamone ontseyo ndjoka tayi ya kwathele meilongo lyawo. Omapekapeko ngano oga longitha omadhiladhiloukithi (eetheori) ga Bernstein’s Pedagogical theori (1990), Genre theori (1996) na Halliday’s Systemic Functional Linguistics theori (1978), mokufatulula nokundjandjukununa iizemo yomapekapeko. Omodela yokukonakona iizemo yongushu tayi ziilile maakonakonwa, oya tala ekonakono ndika onga oshintsa shopokati, oyo ya longithwa, opo ku monike uuyelele wothaathaa. Omikalo dha longifwa mokukonakona noku gongela uuyelele momapekapeko ngano ongaashi, eenkundathana dhayaali, omatalelo geetundi oshoyo omakonakono giinyanyangidhwa tayi kwandjangele nepekapeko ndika. Iizedjemo yepekapeko ndika otayi ulike kutya opena engwangwano montseyo nenge mefatululo lyuukwatya woAcademic Literaci, shoka sha eta enkundipalo meyambidhidho hali pewa aalongwa miilongwa yeewino dhayooloka. Shika otashi ulike kutya kapena etsokumwe pokati keenkambadhala tadhi ningwa kaapudhilongi dhokulonga oAcademic Litraci miilongwa ya yooloka mbyoka tayi ilongelwa kaalongwa miiputudhilo itatu yopombada. iizemmo yepekapeko olyo tuu mdika oya ulike wo kutya aalongwa mboka yaza komailongo ga yooloka oha yi ilongo nuudhigu opo ya pondole ondondo yomadhiladhilo gopombanda meilongo lyuukumwe. Mokukonakona euveko lyoAcademic Literaci, epekapeko ndika olya ndhindhilike kutya aakuthimbinga oyena euveko lyankundipala lyoterma ‘Academic Literaci,’ ano ya nyengwa okukwatakanitha oohedi dhopetameko ndhoka dhina oku ilongwa meikalekelo - ano pondje yiilongwa ikwao. Oshikwao, iizemo oya ulike kutya euveko ndika otali nwetha mo etungepo lyoAcademic Literaci onga oshilongwa, osho wo omakonakono gasho miiputudilo yombombanda itatu yakwatelwa momapekapeko. Hugunina, epekapeko ndika otali ulike/gandja oshiholelwa shomodela ndjoka oAcademic literacy tai vulu okulongwa opo yi kwatelemo eilongo lyiikwatelela kiilongwa osho yo komaitaalo nokeempumbwe dhaalongwa miiputudhilo yopombabda. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning (CHERTL), 2021
- Full Text:
- Authors: Julius, Lukas Homateni
- Date: 2021-04
- Subjects: Information literacy -- Study and teaching (Higher) -- Namibia , Academic writing -- Study and teaching -- Namibia , Qualitative research -- Methodology , Academic language -- Namibia , Information literacy -- Social aspects
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177293 , vital:42807 , 10.21504/10962/177293
- Description: The purpose of this study was to investigate academic literacy development lecturers’ conceptualisations of academic literacy and resultant pedagogical practices in academic development courses at three different Higher Education Institutional types in Namibia. The research sites were a Traditional University, a University of Technology and a Comprehensive University. The focus was to understand the extent to which the academics’ conceptions of academic literacy and the resultant pedagogical practices in the academic development courses at these three Higher Education Institutions (HEIs) facilitate epistemological access into students’ chosen fields of study. Bernstein’s Pedagogical theory (1990), Genre theory (1996) and Halliday’s Systemic Functional Linguistics (1978) were used as the study’s theoretical lenses and analytical framework. An interpretative paradigm and a qualitative case study design were employed as the research approach. Semi-structured interviews, classroom observations and documentary evidence were used to generate data. Research findings revealed a common (mis)conception of the nature of academic literacy, the resultant inadequate learning support offered to students in the selected academic literacy development courses, and a clear divorcing of academic literacy interventions from the students’ ‘home’ or mainstream disciplines at the three HEIs. The participants understood academic literacy from an autonomous position as a set of generic skills which could be taught outside of mainstream classes. Moreover, findings revealed that this understanding impacted on the design and assessments of all the academic literacy courses across the three universities under study. The study calls for a context sensitive model through which academic literacy acquisition can be scaffolded to meet the discipline-specific epistemological needs of the students. , Elalakano lyehokololoningomwa lyomapekapeko ndika olyo okukonakona ehumithokomeho lyomikalo dhokulesha nokushanga meilongngo lyopombada (oAcademic Literaci) maaputudhilongi, okukonakona omafatululo giisimanintsa moAcademic Literaci osho wo okutala iizemo yomikalo dhayooloka dhokulonga noku ilonga iilongwa yayooloka miiputudhilo yelongo lyopombada moNamibia. Omapekapeko ngaka oga li ga ningilwa miiputudhilo yomaukwatya ta ga landula; Oshiputudhiilo shopamudhigululwakalo, Oshiputudhilo shopaunongononi, nOshiputudilo shomailongo gaandjakana. Oshintsa shopokati shomapekapeko ngaka osho okuuva ko ondodo yowino osho wo euveko lyoAcademic Literaci maaputudhilongi nonkene euveko nontseyo ndjika tayi longithwa oku eta oshizemo tashi humitha komeho euveko lyopombanda lyaalongwa yomailongo geewino dhayooloka miiputudhilo itatu yelongo lyopombanda; shino otashi kwathele aalongwa yamone ontseyo ndjoka tayi ya kwathele meilongo lyawo. Omapekapeko ngano oga longitha omadhiladhiloukithi (eetheori) ga Bernstein’s Pedagogical theori (1990), Genre theori (1996) na Halliday’s Systemic Functional Linguistics theori (1978), mokufatulula nokundjandjukununa iizemo yomapekapeko. Omodela yokukonakona iizemo yongushu tayi ziilile maakonakonwa, oya tala ekonakono ndika onga oshintsa shopokati, oyo ya longithwa, opo ku monike uuyelele wothaathaa. Omikalo dha longifwa mokukonakona noku gongela uuyelele momapekapeko ngano ongaashi, eenkundathana dhayaali, omatalelo geetundi oshoyo omakonakono giinyanyangidhwa tayi kwandjangele nepekapeko ndika. Iizedjemo yepekapeko ndika otayi ulike kutya opena engwangwano montseyo nenge mefatululo lyuukwatya woAcademic Literaci, shoka sha eta enkundipalo meyambidhidho hali pewa aalongwa miilongwa yeewino dhayooloka. Shika otashi ulike kutya kapena etsokumwe pokati keenkambadhala tadhi ningwa kaapudhilongi dhokulonga oAcademic Litraci miilongwa ya yooloka mbyoka tayi ilongelwa kaalongwa miiputudhilo itatu yopombada. iizemmo yepekapeko olyo tuu mdika oya ulike wo kutya aalongwa mboka yaza komailongo ga yooloka oha yi ilongo nuudhigu opo ya pondole ondondo yomadhiladhilo gopombanda meilongo lyuukumwe. Mokukonakona euveko lyoAcademic Literaci, epekapeko ndika olya ndhindhilike kutya aakuthimbinga oyena euveko lyankundipala lyoterma ‘Academic Literaci,’ ano ya nyengwa okukwatakanitha oohedi dhopetameko ndhoka dhina oku ilongwa meikalekelo - ano pondje yiilongwa ikwao. Oshikwao, iizemo oya ulike kutya euveko ndika otali nwetha mo etungepo lyoAcademic Literaci onga oshilongwa, osho wo omakonakono gasho miiputudilo yombombanda itatu yakwatelwa momapekapeko. Hugunina, epekapeko ndika otali ulike/gandja oshiholelwa shomodela ndjoka oAcademic literacy tai vulu okulongwa opo yi kwatelemo eilongo lyiikwatelela kiilongwa osho yo komaitaalo nokeempumbwe dhaalongwa miiputudhilo yopombabda. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning (CHERTL), 2021
- Full Text:
Formulation and characterisation of a combination captopril and hydrochlorothiazide microparticulate dosage form for paediatric use
- Chikukwa, Mellisa Tafadzwa Ruramai
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
Determination of nonlinear optical properties of phthalocyanine regioisomers using computational models
- Date: 2020
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Nonlinear optics , Nonlinear optical spectroscopy , Refraction
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166197 , vital:41337
- Description: This work investigates the effects of the nonlinear optical properties of four different constitutional isomers (C4h, C2v, Cs, and D2h) of a series of tetrasubstituted phthalocyanines (free-base 3-4-tert-butylphenoxyether phthalocyanines, free-base 4-4-tertbutylphenoxyether phthalocyanines, SnCl2 tetra substituted 3-4-tert-butylphenoxyether phthalocyanine, and SnCl2 tetra substituted 4-4-tert-butylphenoxyether phthalocyanine). The properties investigated were the real and imaginary components of the 3rd order hyperpolarizability, as well as the excited state absorption and refraction cross sections. The investigations were performed with a z-scan over a range of laser beam intensities. This work determined the imaginary component of the 3rd order hyperpolarizability for the free-base and SnCl2 3-4-tert-butylphenoxyether phthalocyanines and 4-4-tert-butylphenoxyether phthalocyanines to be highly dependent on the excited state cross sections. The refraction caused due to the real component of the 3rd order hyperpolarizability of the phthalocyanines was also investigated, however, the values found were strongly dependent on the laser beam intensity and the cause of this was investigated. A Five-level model was developed and run on GPGPU computing devices in order to isolate the absorption and refractive cross sections. Theeffects of the regio substitution on the excited state cross sections were also investigated, and the 1st singlet excited state and 1st triplet state absorption cross sections were calculated for all constitutional isomers. It was found that the symmetry of the constitutional isomers have a disproportionately large effect on the excited state absorption when compared to the ground state absorption. The nonlinear refractive properties of all constitutional isomers were also investigated, and the values of the parametric susceptibility are reported herein. The nonlinear refraction was found to have less effect than was seen in the nonlinear absorption. The 1st singlet excited state and 1st triplet state refractive cross sections of all constitutional isomer was determined. The results indicated that if more than one excited state was present and contributing to the nonlinear refraction, then more data than was collected here would be required. However, the 1st singlet excited state cross section were successfully determined for the free-base constitutional isomers. This work concluded that the region substitution affected the excited states more than the ground state.
- Full Text:
- Date: 2020
- Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Nonlinear optics , Nonlinear optical spectroscopy , Refraction
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/166197 , vital:41337
- Description: This work investigates the effects of the nonlinear optical properties of four different constitutional isomers (C4h, C2v, Cs, and D2h) of a series of tetrasubstituted phthalocyanines (free-base 3-4-tert-butylphenoxyether phthalocyanines, free-base 4-4-tertbutylphenoxyether phthalocyanines, SnCl2 tetra substituted 3-4-tert-butylphenoxyether phthalocyanine, and SnCl2 tetra substituted 4-4-tert-butylphenoxyether phthalocyanine). The properties investigated were the real and imaginary components of the 3rd order hyperpolarizability, as well as the excited state absorption and refraction cross sections. The investigations were performed with a z-scan over a range of laser beam intensities. This work determined the imaginary component of the 3rd order hyperpolarizability for the free-base and SnCl2 3-4-tert-butylphenoxyether phthalocyanines and 4-4-tert-butylphenoxyether phthalocyanines to be highly dependent on the excited state cross sections. The refraction caused due to the real component of the 3rd order hyperpolarizability of the phthalocyanines was also investigated, however, the values found were strongly dependent on the laser beam intensity and the cause of this was investigated. A Five-level model was developed and run on GPGPU computing devices in order to isolate the absorption and refractive cross sections. Theeffects of the regio substitution on the excited state cross sections were also investigated, and the 1st singlet excited state and 1st triplet state absorption cross sections were calculated for all constitutional isomers. It was found that the symmetry of the constitutional isomers have a disproportionately large effect on the excited state absorption when compared to the ground state absorption. The nonlinear refractive properties of all constitutional isomers were also investigated, and the values of the parametric susceptibility are reported herein. The nonlinear refraction was found to have less effect than was seen in the nonlinear absorption. The 1st singlet excited state and 1st triplet state refractive cross sections of all constitutional isomer was determined. The results indicated that if more than one excited state was present and contributing to the nonlinear refraction, then more data than was collected here would be required. However, the 1st singlet excited state cross section were successfully determined for the free-base constitutional isomers. This work concluded that the region substitution affected the excited states more than the ground state.
- Full Text:
An evaluation of the cytotoxic activities of novel artemisinin derivatives: towards targeted therapies for triple-negative breast cancers (TNBC)
- Authors: Kajewole, Deborah Ifeoluwa
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163329 , vital:41029 , doi:10.21504/10962/163329
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Authors: Kajewole, Deborah Ifeoluwa
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163329 , vital:41029 , doi:10.21504/10962/163329
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
The current role of palm species Hyphaene Coriacea and Phoenix Reclanata in local livelihoods in the Zitundo area, southern Mozambique
- Authors: Martins, Angelina R O
- Date: 2020
- Subjects: Ilala palm -- Economic aspects -- Mozambique , Palms -- Economic aspects -- Mozambique , Non-timber forest products industry -- Mozambique , Sustainable development -- Mozambique , Conservation of natural resources -- Mozambique
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150613 , vital:38989
- Description: The majority of rural households in developing countries are heavily dependent on non-timber forest products (NTFPs) to fulfill much of their basic daily needs. In Mozambique more than 64% of the population lives in rural areas and depends heavily in the extraction of NTFPs to complement agricultural production. One substantial source of NTFPs are palm species. Palms are sources of food, building materials, cloth, ornaments, medicines, and are also used for cultural purposes. In southern Mozambique two important palms species used as NTFPs are Hyphaene coriacea and Phoenix reclinata. These two species provide an array of subsistence and commercial products. The sap, leaves and stems of these two palms are harvested by local people as sources of traditional beverages, weaving, roofing, fencing and furniture material as well as other household utensils. The effects (if any) of harvesting of these palm products on palm distribution, population structure, dynamics and viability have never been examined, and thus the sustainability of the practices and benefits flows to local livelihoods are unknow-n. Any effects harvesting effects may also be exacerbated by predicted climate change for the area. The present study aims to investigate the role of the palm species Hyphaene coriacea and Phoenix reclinata in the livelihoods of households in the Zitundo area, Matutuine district, southern Mozambique and under future climate scenarios. Specifically, this study: i) evaluates the abundance, population structure and harvesting selection of these species; ii) characterizes the ethnobotanical knowledge and use of the two species; iii) examines the local production and trade of palm wine in the area; iv) examines the contribution of palm income to livelihoods and income diversification in area; v) describes the local management practices and perceptions on palm productivity and abundance; and vi) models the current and future distribution of the these palm species in the area. To evaluate the abundance, population structure and stability of these two palm species a population census was carried out, and the size class distribution, Simpson index of dominance, permutation index and the quotient between successive size classes were calculated. I further calculated the preference ratio for specific size classes. Additionally a questionnaire survey was conducted with 179 randomly selected households from the 16 villages in the study area to characterize the ethnobotanical knowledge and use of these two species, as well as to examine the contribution of palm income to livelihoods and diversification. Standard ethnobotanical indices were used as measures of each palm species use and knowledge while principal component analysis and cluster analysis were applied to highlight the livelihood patterns and the role of diversification and of palm income in local livelihoods. Structured interviews with 37 palm tappers were additionally used to examine the local production and trade of palm wine in the area, while both the household survey and palm tappers interviews, were employed to investigate the local management practices and perceptions on palms productivity and abundance. Maxent Software was used to model the current and future under climate change distribution of the two palm species. Hyphaene coriacea was more abundant than Phoenix reclinata. Both species exhibited steep negative slopes in the regression analyses of size class distribution, indicating the presence of more individuals in shorter size classes. Although there was a dominance of shorter over taller size classes, limited recruitment was observed through low stem densities of seedlings and juveniles compared to the 1-50 cm size class The Simpson index of dominance, the permutation index, and the fluctuating quotients between the consecutive size classes showed a level of instability in both populations. Hyphaene coriacea appeared to be more resilient to tapping than Phoenix reclinata as showed by the higher rate of stem survival after tapping. Hyphaene coriacea was favored for tapping compared to Phoenix reclinata. The most preferred size class to tap for both species was between 101cm and 150 cm. Currently the distribution of Hyphaene coriacea and Phoenix reclinata was mostly confined to the eastern side of the study area. Most of the area was predicted as unsuitable for both palm species, with less than six percent predicted to be suitable or higher. The occurrence of both species appeared to be influenced mostly by water related variables, such as precipitation, and distance to rivers and distance to water bodies. The habitat suitability for Hyphaene coriacea was predicted to increase under future climate conditions scenarios, while little variation was predicted for Phoenix reclinata distribution. The knowledge about the uses of these two palm species was widespread in the area, although only 32% of respondents were engaged in palm exploitation. Thirteen palm products were exploited, with palm wine production from the sap of both palms being the dominant activity, followed by broom production from Phoenix reclinata stems and basket production from Hyphaene coriacea leaves. The cultural importance of these species included the production of anklets and skirts used during traditional dances and the use of palm wine in the traditional ritual of libation. Palm tapping was practiced year round in five of the sixteen villages in the area. Palm tapping was an important livelihood activity, contributing over 80% of tappers’ total annual income, and tappers earned up to three times more than the national minimum wage for the agricultural and forestry sector. Palm wine was also a highly commercial commodity in Zitundo area, with an average commercialization index above 60%. The income from palm wine sales showed an important role in mitigating the level of poverty in the area. Palm income accounted for over 60% reduction on poverty incidence among palm tappers. Households in Zitundo further engaged in some level of livelihood diversification. The majority of households adopted a wage-based strategy, although this strategy was among the less remunerative in terms of per capita cash income. A palm-based livelihood strategy, although adopted only by 11% of households, was one of the most remunerative strategies. Palm income played a vital role in enhancing household livelihoods and mitigating poverty in the area as shown by the lower poverty incidences among households engaged in the palm-based livelihood strategy than alternatives strategies. The village of household residency, along with household demographic and socio-economic characteristics appeared to determine the knowledge and exploitation level of palms as well as a households’ choice of livelihood strategy, level of palm wine returns, commercialization index and palm income dependency. The importance of palms in local livelihoods and poverty alleviation needs greater acknowledgement by government and development agencies in the area. Palm wine, broom and basket production have a high potential for income generation, and therefore should be included in future local development policies and poverty reduction strategies. Although palms are an open access resource in Zitundo area, the perception is that they are abundant and that tapping does not have many detrimental effects. However, this study found some negative impacts of tapping on the recruitment of both palms species. The inclusion of palm products in future development programs and poverty reduction strategies will require the design of participatory conservation and management strategies that involve all palm users groups and others stakeholders and include long-term participatory monitoring of the effect of palm use on the populations.
- Full Text:
- Authors: Martins, Angelina R O
- Date: 2020
- Subjects: Ilala palm -- Economic aspects -- Mozambique , Palms -- Economic aspects -- Mozambique , Non-timber forest products industry -- Mozambique , Sustainable development -- Mozambique , Conservation of natural resources -- Mozambique
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150613 , vital:38989
- Description: The majority of rural households in developing countries are heavily dependent on non-timber forest products (NTFPs) to fulfill much of their basic daily needs. In Mozambique more than 64% of the population lives in rural areas and depends heavily in the extraction of NTFPs to complement agricultural production. One substantial source of NTFPs are palm species. Palms are sources of food, building materials, cloth, ornaments, medicines, and are also used for cultural purposes. In southern Mozambique two important palms species used as NTFPs are Hyphaene coriacea and Phoenix reclinata. These two species provide an array of subsistence and commercial products. The sap, leaves and stems of these two palms are harvested by local people as sources of traditional beverages, weaving, roofing, fencing and furniture material as well as other household utensils. The effects (if any) of harvesting of these palm products on palm distribution, population structure, dynamics and viability have never been examined, and thus the sustainability of the practices and benefits flows to local livelihoods are unknow-n. Any effects harvesting effects may also be exacerbated by predicted climate change for the area. The present study aims to investigate the role of the palm species Hyphaene coriacea and Phoenix reclinata in the livelihoods of households in the Zitundo area, Matutuine district, southern Mozambique and under future climate scenarios. Specifically, this study: i) evaluates the abundance, population structure and harvesting selection of these species; ii) characterizes the ethnobotanical knowledge and use of the two species; iii) examines the local production and trade of palm wine in the area; iv) examines the contribution of palm income to livelihoods and income diversification in area; v) describes the local management practices and perceptions on palm productivity and abundance; and vi) models the current and future distribution of the these palm species in the area. To evaluate the abundance, population structure and stability of these two palm species a population census was carried out, and the size class distribution, Simpson index of dominance, permutation index and the quotient between successive size classes were calculated. I further calculated the preference ratio for specific size classes. Additionally a questionnaire survey was conducted with 179 randomly selected households from the 16 villages in the study area to characterize the ethnobotanical knowledge and use of these two species, as well as to examine the contribution of palm income to livelihoods and diversification. Standard ethnobotanical indices were used as measures of each palm species use and knowledge while principal component analysis and cluster analysis were applied to highlight the livelihood patterns and the role of diversification and of palm income in local livelihoods. Structured interviews with 37 palm tappers were additionally used to examine the local production and trade of palm wine in the area, while both the household survey and palm tappers interviews, were employed to investigate the local management practices and perceptions on palms productivity and abundance. Maxent Software was used to model the current and future under climate change distribution of the two palm species. Hyphaene coriacea was more abundant than Phoenix reclinata. Both species exhibited steep negative slopes in the regression analyses of size class distribution, indicating the presence of more individuals in shorter size classes. Although there was a dominance of shorter over taller size classes, limited recruitment was observed through low stem densities of seedlings and juveniles compared to the 1-50 cm size class The Simpson index of dominance, the permutation index, and the fluctuating quotients between the consecutive size classes showed a level of instability in both populations. Hyphaene coriacea appeared to be more resilient to tapping than Phoenix reclinata as showed by the higher rate of stem survival after tapping. Hyphaene coriacea was favored for tapping compared to Phoenix reclinata. The most preferred size class to tap for both species was between 101cm and 150 cm. Currently the distribution of Hyphaene coriacea and Phoenix reclinata was mostly confined to the eastern side of the study area. Most of the area was predicted as unsuitable for both palm species, with less than six percent predicted to be suitable or higher. The occurrence of both species appeared to be influenced mostly by water related variables, such as precipitation, and distance to rivers and distance to water bodies. The habitat suitability for Hyphaene coriacea was predicted to increase under future climate conditions scenarios, while little variation was predicted for Phoenix reclinata distribution. The knowledge about the uses of these two palm species was widespread in the area, although only 32% of respondents were engaged in palm exploitation. Thirteen palm products were exploited, with palm wine production from the sap of both palms being the dominant activity, followed by broom production from Phoenix reclinata stems and basket production from Hyphaene coriacea leaves. The cultural importance of these species included the production of anklets and skirts used during traditional dances and the use of palm wine in the traditional ritual of libation. Palm tapping was practiced year round in five of the sixteen villages in the area. Palm tapping was an important livelihood activity, contributing over 80% of tappers’ total annual income, and tappers earned up to three times more than the national minimum wage for the agricultural and forestry sector. Palm wine was also a highly commercial commodity in Zitundo area, with an average commercialization index above 60%. The income from palm wine sales showed an important role in mitigating the level of poverty in the area. Palm income accounted for over 60% reduction on poverty incidence among palm tappers. Households in Zitundo further engaged in some level of livelihood diversification. The majority of households adopted a wage-based strategy, although this strategy was among the less remunerative in terms of per capita cash income. A palm-based livelihood strategy, although adopted only by 11% of households, was one of the most remunerative strategies. Palm income played a vital role in enhancing household livelihoods and mitigating poverty in the area as shown by the lower poverty incidences among households engaged in the palm-based livelihood strategy than alternatives strategies. The village of household residency, along with household demographic and socio-economic characteristics appeared to determine the knowledge and exploitation level of palms as well as a households’ choice of livelihood strategy, level of palm wine returns, commercialization index and palm income dependency. The importance of palms in local livelihoods and poverty alleviation needs greater acknowledgement by government and development agencies in the area. Palm wine, broom and basket production have a high potential for income generation, and therefore should be included in future local development policies and poverty reduction strategies. Although palms are an open access resource in Zitundo area, the perception is that they are abundant and that tapping does not have many detrimental effects. However, this study found some negative impacts of tapping on the recruitment of both palms species. The inclusion of palm products in future development programs and poverty reduction strategies will require the design of participatory conservation and management strategies that involve all palm users groups and others stakeholders and include long-term participatory monitoring of the effect of palm use on the populations.
- Full Text:
CO2-induced woody thickening depends strongly on interacting abiotic and biotic factors
- Authors: Raubenheimer, Sarah Lynn
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164646 , vital:41151 , doi:10.21504/10962/164646
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Botany, 2020
- Full Text:
- Authors: Raubenheimer, Sarah Lynn
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164646 , vital:41151 , doi:10.21504/10962/164646
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Botany, 2020
- Full Text: