Damage recovery for robot controllers and simulators evolved using bootstrapped neuro-simulation
- Authors: Leonard, Brydon Andrew
- Date: 2019
- Subjects: Robots -- Control systems , Robots -- Programming Robotics Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40424 , vital:36164
- Description: Robots are becoming increasingly complex. This has made manually designing the software responsible for controlling these robots (controllers) challenging, leading to the creation of the field of evolutionary robotics (ER). The ER approach aims to automatically evolve robot controllers and morphologies by utilising concepts from biological evolution. ER techniques use evolutionary algorithms (EA) to evolve populations of controllers - a process that requires the evaluation of a large number of controllers. Performing these evaluations on a real-world robot is both infeasibly time-consuming and poses the risk of damage to the robot. Simulators present a solution to the issue by allowing the evaluation of controllers to take place on a virtual robot. Traditional methods of controller evolution in simulation encounter two major issues. Firstly, physics simulators are complex to create and are often very computationally expensive. Secondly, the reality gap is encountered when controllers are evolved in simulators that are unable to simulate the real world well enough due to implications or small inaccuracies in the simulation, which together cause controllers in the simulation to be unable to transfer effectively to reality. Bootstrapped Neuro-Simulation (BNS) is an ER algorithm that aims to address the issues inherent with the use of simulators. The algorithm concurrently creates a simulator and evolves a population of controllers. The process starts with an initially random population of controllers and an untrained simulator neural network (SNN), a type of robot simulator which utilises artificial neural networks (ANNs) to simulate a robot's behaviour. Controllers are then continually selected for evaluation in the real world, and the data from these real-world evaluations is used to train the controller-evaluation SNN. BNS is a relatively new algorithm that has not yet been explored in depth. An investigation was, therefore, conducted into BNS's ability to evolve closed-loop controllers. BNS was successful in evolving such controllers, and various adaptations to the algorithm were investigated for their ability to improve the evolution of closed-loop controllers. In addition, the factors which had the greatest impact on BNS's effectiveness were reported upon. Damage recovery is an area that has been the focus of a great deal of research. This is because the progression of the field of robotics means that robots no longer operate only in the safe environments that they once did. Robots are now put to use in areas as inaccessible as the surface of Mars, where repairs by a human are impossible. Various methods of damage recovery have previously been proposed and evaluated, but none focused on BNS as a method of damage recovery. In this research, it was hypothesised that BNS's constantly learning nature would allow it to recover from damage, as it would continue to use new information about the state of the real robot to evolve new controllers capable of functioning in the damaged robot. BNS was found to possess the hypothesised damage recovery ability. The algorithm's evaluation was carried out through the evolution of controllers for simple navigation and light-following tasks for a wheeled robot, as well as a locomotion task for a complex legged robot. Various adaptations to the algorithm were then evaluated through extensive parameter investigations in simulation, showing varying levels of effectiveness. These results were further confirmed through evaluation of the adaptations and effective parameter values in real-world evaluations on a real robot. Both a simple and more complex robot morphology were investigated.
- Full Text:
- Date Issued: 2019
- Authors: Leonard, Brydon Andrew
- Date: 2019
- Subjects: Robots -- Control systems , Robots -- Programming Robotics Neural networks (Computer science)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40424 , vital:36164
- Description: Robots are becoming increasingly complex. This has made manually designing the software responsible for controlling these robots (controllers) challenging, leading to the creation of the field of evolutionary robotics (ER). The ER approach aims to automatically evolve robot controllers and morphologies by utilising concepts from biological evolution. ER techniques use evolutionary algorithms (EA) to evolve populations of controllers - a process that requires the evaluation of a large number of controllers. Performing these evaluations on a real-world robot is both infeasibly time-consuming and poses the risk of damage to the robot. Simulators present a solution to the issue by allowing the evaluation of controllers to take place on a virtual robot. Traditional methods of controller evolution in simulation encounter two major issues. Firstly, physics simulators are complex to create and are often very computationally expensive. Secondly, the reality gap is encountered when controllers are evolved in simulators that are unable to simulate the real world well enough due to implications or small inaccuracies in the simulation, which together cause controllers in the simulation to be unable to transfer effectively to reality. Bootstrapped Neuro-Simulation (BNS) is an ER algorithm that aims to address the issues inherent with the use of simulators. The algorithm concurrently creates a simulator and evolves a population of controllers. The process starts with an initially random population of controllers and an untrained simulator neural network (SNN), a type of robot simulator which utilises artificial neural networks (ANNs) to simulate a robot's behaviour. Controllers are then continually selected for evaluation in the real world, and the data from these real-world evaluations is used to train the controller-evaluation SNN. BNS is a relatively new algorithm that has not yet been explored in depth. An investigation was, therefore, conducted into BNS's ability to evolve closed-loop controllers. BNS was successful in evolving such controllers, and various adaptations to the algorithm were investigated for their ability to improve the evolution of closed-loop controllers. In addition, the factors which had the greatest impact on BNS's effectiveness were reported upon. Damage recovery is an area that has been the focus of a great deal of research. This is because the progression of the field of robotics means that robots no longer operate only in the safe environments that they once did. Robots are now put to use in areas as inaccessible as the surface of Mars, where repairs by a human are impossible. Various methods of damage recovery have previously been proposed and evaluated, but none focused on BNS as a method of damage recovery. In this research, it was hypothesised that BNS's constantly learning nature would allow it to recover from damage, as it would continue to use new information about the state of the real robot to evolve new controllers capable of functioning in the damaged robot. BNS was found to possess the hypothesised damage recovery ability. The algorithm's evaluation was carried out through the evolution of controllers for simple navigation and light-following tasks for a wheeled robot, as well as a locomotion task for a complex legged robot. Various adaptations to the algorithm were then evaluated through extensive parameter investigations in simulation, showing varying levels of effectiveness. These results were further confirmed through evaluation of the adaptations and effective parameter values in real-world evaluations on a real robot. Both a simple and more complex robot morphology were investigated.
- Full Text:
- Date Issued: 2019
Exploring how millennials prepare their content for social media: a narrative study of online users
- Authors: Coleman, Robyn-Ann
- Date: 2019
- Subjects: Generation Y
- Language: English
- Type: Thesis , Masters , MSW
- Identifier: http://hdl.handle.net/10353/17542 , vital:41089
- Description: Millennials, (born between 1982 to 1996) referred to as ‘techno savvy’, are the largest and most highly educated generational cohort in this time. Introduced to technology early on in their lives has lead to a prolific use of social media. As possible future leaders, millennials also have the highest employment turnaround. The increased turnaround is because millennials are always on the lookout for better opportunities and purpose to meet their need for accelerated growth together with their need to belong. Social media platforms have the propensity to provide instantaneous and gratifying rewards, through various ways including self disclosure online. As millennials are seeking purpose and reward, communicating on a social media platform is way more rewarding than attempting to communicate. With the arena of face to face communication shifting to online communication this is becoming more amplified. This research study explored how millennials prepared to portray their content on Facebook and Instagram. A biographical narrative approach effectively acquired 15 individual millennials in-depth co-constructed narratives on how they prepare their online social media, and analysed through contexualising the co-constructed into a re-storied narrative with Connelly & Clandinin’s (2009) narrative analysis approach. Goffman’s dramaturgical approach, a conceptual framework based on micro social interaction was used to obtain insight into millennials online portrayal. The findings revealed that all of the participants utilised one or more of the following dramaturgical metaphors to portray themselves; a) they utilised props and /or filters to set the environment and filter their image online, b) they managed their impressions by being intentional in the selection of their images, and c) by intentionally selecting images or messages that portray roles their audience would affirm them for. The findings of this study highlights and provides insight in millennials’ preoccupation, distraction and portrayal online, which feeds into their need to be seen in a positive light and be affirmed. These findings provide social workers with new insight and perspective into millennials unspoken rich indepth narratives when millennials portray themselves online
- Full Text:
- Date Issued: 2019
- Authors: Coleman, Robyn-Ann
- Date: 2019
- Subjects: Generation Y
- Language: English
- Type: Thesis , Masters , MSW
- Identifier: http://hdl.handle.net/10353/17542 , vital:41089
- Description: Millennials, (born between 1982 to 1996) referred to as ‘techno savvy’, are the largest and most highly educated generational cohort in this time. Introduced to technology early on in their lives has lead to a prolific use of social media. As possible future leaders, millennials also have the highest employment turnaround. The increased turnaround is because millennials are always on the lookout for better opportunities and purpose to meet their need for accelerated growth together with their need to belong. Social media platforms have the propensity to provide instantaneous and gratifying rewards, through various ways including self disclosure online. As millennials are seeking purpose and reward, communicating on a social media platform is way more rewarding than attempting to communicate. With the arena of face to face communication shifting to online communication this is becoming more amplified. This research study explored how millennials prepared to portray their content on Facebook and Instagram. A biographical narrative approach effectively acquired 15 individual millennials in-depth co-constructed narratives on how they prepare their online social media, and analysed through contexualising the co-constructed into a re-storied narrative with Connelly & Clandinin’s (2009) narrative analysis approach. Goffman’s dramaturgical approach, a conceptual framework based on micro social interaction was used to obtain insight into millennials online portrayal. The findings revealed that all of the participants utilised one or more of the following dramaturgical metaphors to portray themselves; a) they utilised props and /or filters to set the environment and filter their image online, b) they managed their impressions by being intentional in the selection of their images, and c) by intentionally selecting images or messages that portray roles their audience would affirm them for. The findings of this study highlights and provides insight in millennials’ preoccupation, distraction and portrayal online, which feeds into their need to be seen in a positive light and be affirmed. These findings provide social workers with new insight and perspective into millennials unspoken rich indepth narratives when millennials portray themselves online
- Full Text:
- Date Issued: 2019
Incidence of cholera-causing and non cholera-causing pathogenic vibrio species in the river-k and two of its feeder wastewater treatment plants in the Raymond Mhlaba municipality, Eastern Cape province of South Africa
- Authors: Gcilitshana, Onele
- Date: 2019
- Subjects: Water -- Purification -- South Africa -- Eastern Cape Effluent quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15145 , vital:40190
- Description: Despite technological advances in water treatment and improved sanitation in many developing countries, acute microbial diseases still thrive and continue to distress millions of people. This is due to the high number of rural dwellers that still source water for drinking and other domestic uses from contaminated rivers. In South Africa, there have been reports on waterborne disease outbreaks, and specifically in the area understudy, two records of diarrhoeal outbreaks associated with consumption of river water were reported within the last decade. All those outbreaks and previous reports on isolation of other pathogenic bacteria within the area necessitated the conduction of this study in order to identify the potential causes of the cholera-associate diarrheal outbreaks previously reported in the area and nationally. This study was designed to assess the incidence of cholera-causing and non-cholera causing pathogens in final effluents and surface waters of the Raymond Mhlaba Local Municipality, Eastern Cape Province, South Africa. RiverK which serves as a major resource for domestic activities, agricultural practices as well as an abstraction point for a potable water treatment plant was used for this study. River-K freshwater and final effluents of its two feeder wastewater treatment plants were sampled monthly, over a twelve-month period (December 2016–November 2017). For purposes of confidentiality, the names of the wastewater treatment plants and river involved are coded in this report. A total of 108 water samples were assessed for the physicochemical parameters that influence the presence of Vibrio pathogens. For bacteriology, the membrane filtration method followed by polymerase chain reaction (PCR) was adopted to assess the incidence of cholera-causing and non-choleracausing Vibrio pathogens, as well as their virulence-associated genes from the two wastewater treatment plants and their receiving waterbody (River-K). Antibiotic susceptibility profiles of identified Vibrio species were determined using the disc diffusion method against a panel of xvi sixteen antibiotics commonly used as antimicrobial drugs of Vibrio infections. Multiple antibiotics resistance index (MARI) and phenotypes (MARP) were measured, and the existence of antibiotic resistance genes was evaluated by PCR using specific primer sets. Most of the physicochemical parameters measured (pH, TDS, temperature, salinity and DO) complied with the recommended standards for drinking water, while some fell short of the recommended limits (EC, turbidity, TSS, free chlorine). From the presumptive Vibrio isolates, 64.3% (476/740) were confirmed by PCR, with their Vibrio densities across all sampling points ranging between 0 and 2.7 × 104 CFU/100 mL, with high counts recorded in summer, hence their positive significant correlation (P< 0.01) with temperature. From the confirmed Vibrio isolates, only V. cholerae (53/476), V. mimicus (21/476) and V. parahaemolyticus (5/476) were detected. For virulence-associated genes, virulence genes homologous to V. cholerae virulence determinants, namely ompU (35%), TCP (14%), ACE (11%), ctx (7%) and HylA (4.5%) were widespread (independently) amongst the V. cholerae and V. mimicus species, while V. parahemolyticus isolates (100%) produced only the ToxR gene. Antibiogram profiling found resistance against some antibiotics such as Nalidixic acid (65%), Polymyxin B (43.8%) etc. The MAR indices ranged between 0 and 0.67 with 41.3% of the isolates recording MAR index values above 0.2. The results presented high degrees of MARPs ranging from four to eleven antimicrobials. For resistance gene detection, the SXT element was detected in 66% of the isolates, while cat1 (93%) was the most predominant, followed by aac (68%), ant (61%), with bla-V (7.1%) as the least detected gene. Findings from this study suggest that the wastewater effluents from the two wastewater treatment plants are potential sources of pathogenic Vibrio species and River-K contains a high quantity of pathogenic Vibrio species with fluctuating seasonal variations that reaffirm temperature as a strong reason for their abundance. The antibiotic-resistant Vibrio species isolated here carry a pool of virulence-associated genes and xvii antibiotic resistance genes, presenting a health threat to the communities that use it directly for domestic and irrigation purposes. In conclusion, some surface waters in the Eastern Cape Province, South Africa are widely contaminated with cholera-causing and non-cholera causing Vibrio pathogens; furthermore, some wastewater treatment plants are ineffective in adequately removing microbial contaminants and have become sources of pathogenic bacteria to their receiving waterbodie
- Full Text:
- Date Issued: 2019
- Authors: Gcilitshana, Onele
- Date: 2019
- Subjects: Water -- Purification -- South Africa -- Eastern Cape Effluent quality -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/15145 , vital:40190
- Description: Despite technological advances in water treatment and improved sanitation in many developing countries, acute microbial diseases still thrive and continue to distress millions of people. This is due to the high number of rural dwellers that still source water for drinking and other domestic uses from contaminated rivers. In South Africa, there have been reports on waterborne disease outbreaks, and specifically in the area understudy, two records of diarrhoeal outbreaks associated with consumption of river water were reported within the last decade. All those outbreaks and previous reports on isolation of other pathogenic bacteria within the area necessitated the conduction of this study in order to identify the potential causes of the cholera-associate diarrheal outbreaks previously reported in the area and nationally. This study was designed to assess the incidence of cholera-causing and non-cholera causing pathogens in final effluents and surface waters of the Raymond Mhlaba Local Municipality, Eastern Cape Province, South Africa. RiverK which serves as a major resource for domestic activities, agricultural practices as well as an abstraction point for a potable water treatment plant was used for this study. River-K freshwater and final effluents of its two feeder wastewater treatment plants were sampled monthly, over a twelve-month period (December 2016–November 2017). For purposes of confidentiality, the names of the wastewater treatment plants and river involved are coded in this report. A total of 108 water samples were assessed for the physicochemical parameters that influence the presence of Vibrio pathogens. For bacteriology, the membrane filtration method followed by polymerase chain reaction (PCR) was adopted to assess the incidence of cholera-causing and non-choleracausing Vibrio pathogens, as well as their virulence-associated genes from the two wastewater treatment plants and their receiving waterbody (River-K). Antibiotic susceptibility profiles of identified Vibrio species were determined using the disc diffusion method against a panel of xvi sixteen antibiotics commonly used as antimicrobial drugs of Vibrio infections. Multiple antibiotics resistance index (MARI) and phenotypes (MARP) were measured, and the existence of antibiotic resistance genes was evaluated by PCR using specific primer sets. Most of the physicochemical parameters measured (pH, TDS, temperature, salinity and DO) complied with the recommended standards for drinking water, while some fell short of the recommended limits (EC, turbidity, TSS, free chlorine). From the presumptive Vibrio isolates, 64.3% (476/740) were confirmed by PCR, with their Vibrio densities across all sampling points ranging between 0 and 2.7 × 104 CFU/100 mL, with high counts recorded in summer, hence their positive significant correlation (P< 0.01) with temperature. From the confirmed Vibrio isolates, only V. cholerae (53/476), V. mimicus (21/476) and V. parahaemolyticus (5/476) were detected. For virulence-associated genes, virulence genes homologous to V. cholerae virulence determinants, namely ompU (35%), TCP (14%), ACE (11%), ctx (7%) and HylA (4.5%) were widespread (independently) amongst the V. cholerae and V. mimicus species, while V. parahemolyticus isolates (100%) produced only the ToxR gene. Antibiogram profiling found resistance against some antibiotics such as Nalidixic acid (65%), Polymyxin B (43.8%) etc. The MAR indices ranged between 0 and 0.67 with 41.3% of the isolates recording MAR index values above 0.2. The results presented high degrees of MARPs ranging from four to eleven antimicrobials. For resistance gene detection, the SXT element was detected in 66% of the isolates, while cat1 (93%) was the most predominant, followed by aac (68%), ant (61%), with bla-V (7.1%) as the least detected gene. Findings from this study suggest that the wastewater effluents from the two wastewater treatment plants are potential sources of pathogenic Vibrio species and River-K contains a high quantity of pathogenic Vibrio species with fluctuating seasonal variations that reaffirm temperature as a strong reason for their abundance. The antibiotic-resistant Vibrio species isolated here carry a pool of virulence-associated genes and xvii antibiotic resistance genes, presenting a health threat to the communities that use it directly for domestic and irrigation purposes. In conclusion, some surface waters in the Eastern Cape Province, South Africa are widely contaminated with cholera-causing and non-cholera causing Vibrio pathogens; furthermore, some wastewater treatment plants are ineffective in adequately removing microbial contaminants and have become sources of pathogenic bacteria to their receiving waterbodie
- Full Text:
- Date Issued: 2019
A study of the southwestern Karoo basin in South Africa using magnetic and gravity data
- Authors: Nxantsiya, Zusakhe
- Date: 2017
- Subjects: Groundwater -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14043 , vital:39800
- Description: The early efforts of Booth, Johnson, Rubidge, Catuneanu, de Wit, Chevallier, Stankiewicz, Weckmann and many other scientists in studying the Karoo Supergroup has led to comprehensive documentation of the geology on the main Karoo Basin with regards to understanding the age, sedimentology, sedimentary facies and depositional environments. In spite of these studies, the subsurface structure, variations in thickness of various formations in large parts of the basin, the location and orientation of subsurface dolerite intrusions, and the depth to magnetic and gravity sources remains poorly documented. A geological study with the aid of geophysical techniques, magnetic and gravity, was conducted in the southwestern part of the main Karoo Basin. The objectives of the study were to construct numerous models of the main basin that image the crust to a depth of 45 km, to determine thicknesses of various formations, to relate observed geophysical anomalies with geological bodies and lineaments, to estimate the depth of existing anomalous bodies, to determine densities and porosity of various formations, as well as to determine the mineralogy of various rocks in the Karoo Basin. In total, seventy one rock samples were collected in the main Karoo Basin for density and mineralogical studies. The density results showed that the Beaufort and Ecca Group rocks have the low mean density of 2.490 g/cm3 amongst the rocks while the dolerite intrusions have the highest mean density of 2.697 g/cm3. The porosities of various rocks determined from the measured rock densities revealed that the Ecca Group shales, particularly the Whitehill Formation has the highest porosity of 4.5percent, while the Collingham Formation has the least porosity of 1.4 percent amongst the Ecca Group shales. Mineralogical analysis of seventeen XRD samples and 26 thin sections indicate that quartz, kaolinite, and plagioclase occur as the major mineral in most sandstones and shales in the Karoo Basin, while the pyrophyllite, smectite, and talc occur as minor minerals. Other mineral constituents include, calcite, mica, and amphibole. The 2½ dimensional (2½ D) gravity modelling along seven selected profiles, across the Beattie Magnetic Anomaly (BMA), revealed that the Ecca Group sediments, a target for shale gas exploration in the Karoo, occurs within a depth range of 0 - 4000 m from the surface. The basin deepens to a depth of 4600 m in the southwestern region, near the front of the Cape Fold Belt. It was observed as well that the Karoo dolerite sills are connected at depths and are mostly concentrated at the centre, the deepest part of the basin with some having saucer shape - like structure. These observations correspond well with the borehole data from AB 1/65 and QU 1/65 presented in Linol and de Wit (2016). Thickness isochore maps that were extracted from the gravity models indicate that the Ecca Group, which is the main target for hydrocarbon exploration, thickens to the south away from the centre of the basin and reaches thicknesses of greater than 3680 m. The Beaufort Group proves to be the thickest succession in the Karoo Basin with an estimated thickness of up to 6046 m. Constructed geophysical maps with the geology overlain reveal that most magnetic anomalies are due to dolerite intrusions, while gravity lows are due to less dense shales of the Ecca Group. The depth slices of magnetic data indicate that near surface magnetic bodies occur within the depth of 42 m from the surface whereas deep seated ones occur as deep as 9488 m and possibly deeper. Gravity depth slices reveal signatures that are predominant at depth of 2403 m are of short wavelength and are mainly lineaments and circular structures. They ultimately disappear at depth of 7120 m. The depth slices further indicate that the intensity of both magnetic and gravity long wavelength signatures become stronger with increasing depths.
- Full Text:
- Date Issued: 2017
- Authors: Nxantsiya, Zusakhe
- Date: 2017
- Subjects: Groundwater -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14043 , vital:39800
- Description: The early efforts of Booth, Johnson, Rubidge, Catuneanu, de Wit, Chevallier, Stankiewicz, Weckmann and many other scientists in studying the Karoo Supergroup has led to comprehensive documentation of the geology on the main Karoo Basin with regards to understanding the age, sedimentology, sedimentary facies and depositional environments. In spite of these studies, the subsurface structure, variations in thickness of various formations in large parts of the basin, the location and orientation of subsurface dolerite intrusions, and the depth to magnetic and gravity sources remains poorly documented. A geological study with the aid of geophysical techniques, magnetic and gravity, was conducted in the southwestern part of the main Karoo Basin. The objectives of the study were to construct numerous models of the main basin that image the crust to a depth of 45 km, to determine thicknesses of various formations, to relate observed geophysical anomalies with geological bodies and lineaments, to estimate the depth of existing anomalous bodies, to determine densities and porosity of various formations, as well as to determine the mineralogy of various rocks in the Karoo Basin. In total, seventy one rock samples were collected in the main Karoo Basin for density and mineralogical studies. The density results showed that the Beaufort and Ecca Group rocks have the low mean density of 2.490 g/cm3 amongst the rocks while the dolerite intrusions have the highest mean density of 2.697 g/cm3. The porosities of various rocks determined from the measured rock densities revealed that the Ecca Group shales, particularly the Whitehill Formation has the highest porosity of 4.5percent, while the Collingham Formation has the least porosity of 1.4 percent amongst the Ecca Group shales. Mineralogical analysis of seventeen XRD samples and 26 thin sections indicate that quartz, kaolinite, and plagioclase occur as the major mineral in most sandstones and shales in the Karoo Basin, while the pyrophyllite, smectite, and talc occur as minor minerals. Other mineral constituents include, calcite, mica, and amphibole. The 2½ dimensional (2½ D) gravity modelling along seven selected profiles, across the Beattie Magnetic Anomaly (BMA), revealed that the Ecca Group sediments, a target for shale gas exploration in the Karoo, occurs within a depth range of 0 - 4000 m from the surface. The basin deepens to a depth of 4600 m in the southwestern region, near the front of the Cape Fold Belt. It was observed as well that the Karoo dolerite sills are connected at depths and are mostly concentrated at the centre, the deepest part of the basin with some having saucer shape - like structure. These observations correspond well with the borehole data from AB 1/65 and QU 1/65 presented in Linol and de Wit (2016). Thickness isochore maps that were extracted from the gravity models indicate that the Ecca Group, which is the main target for hydrocarbon exploration, thickens to the south away from the centre of the basin and reaches thicknesses of greater than 3680 m. The Beaufort Group proves to be the thickest succession in the Karoo Basin with an estimated thickness of up to 6046 m. Constructed geophysical maps with the geology overlain reveal that most magnetic anomalies are due to dolerite intrusions, while gravity lows are due to less dense shales of the Ecca Group. The depth slices of magnetic data indicate that near surface magnetic bodies occur within the depth of 42 m from the surface whereas deep seated ones occur as deep as 9488 m and possibly deeper. Gravity depth slices reveal signatures that are predominant at depth of 2403 m are of short wavelength and are mainly lineaments and circular structures. They ultimately disappear at depth of 7120 m. The depth slices further indicate that the intensity of both magnetic and gravity long wavelength signatures become stronger with increasing depths.
- Full Text:
- Date Issued: 2017
A study of the southwestern Karoo basin in South Africa using magnetic and gravity data
- Authors: Nxantsiya, Zusakhe
- Date: 2017
- Subjects: Groundwater -- South Africa -- Karoo Aquifers -- South Africa -- Karoo Hydrology -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/4748 , vital:28509
- Description: The early efforts of Booth, Johnson, Rubidge, Catuneanu, de Wit, Chevallier, Stankiewicz, Weckmann and many other scientists in studying the Karoo Supergroup has led to comprehensive documentation of the geology on the main Karoo Basin with regards to understanding the age, sedimentology, sedimentary facies and depositional environments. In spite of these studies, the subsurface structure, variations in thickness of various formations in large parts of the basin, the location and orientation of subsurface dolerite intrusions, and the depth to magnetic and gravity sources remains poorly documented. A geological study with the aid of geophysical techniques, magnetic and gravity, was conducted in the southwestern part of the main Karoo Basin. The objectives of the study were to construct numerous models of the main basin that image the crust to a depth of 45 km, to determine thicknesses of various formations, to relate observed geophysical anomalies with geological bodies and lineaments, to estimate the depth of existing anomalous bodies, to determine densities and porosity of various formations, as well as to determine the mineralogy of various rocks in the Karoo Basin.
- Full Text:
- Date Issued: 2017
- Authors: Nxantsiya, Zusakhe
- Date: 2017
- Subjects: Groundwater -- South Africa -- Karoo Aquifers -- South Africa -- Karoo Hydrology -- South Africa -- Karoo
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/4748 , vital:28509
- Description: The early efforts of Booth, Johnson, Rubidge, Catuneanu, de Wit, Chevallier, Stankiewicz, Weckmann and many other scientists in studying the Karoo Supergroup has led to comprehensive documentation of the geology on the main Karoo Basin with regards to understanding the age, sedimentology, sedimentary facies and depositional environments. In spite of these studies, the subsurface structure, variations in thickness of various formations in large parts of the basin, the location and orientation of subsurface dolerite intrusions, and the depth to magnetic and gravity sources remains poorly documented. A geological study with the aid of geophysical techniques, magnetic and gravity, was conducted in the southwestern part of the main Karoo Basin. The objectives of the study were to construct numerous models of the main basin that image the crust to a depth of 45 km, to determine thicknesses of various formations, to relate observed geophysical anomalies with geological bodies and lineaments, to estimate the depth of existing anomalous bodies, to determine densities and porosity of various formations, as well as to determine the mineralogy of various rocks in the Karoo Basin.
- Full Text:
- Date Issued: 2017
The stability of tolerance of Sorghum spp to Striga asiatica L. Kuntze under diverse conditions and existence of pre-attachment resistance
- Authors: Mandumbu, Ronald
- Date: 2017
- Subjects: Sorghum Sorghum -- Drought tolerance Sorghum -- Effect of drought on
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2788 , vital:28088
- Description: Sorghum is the fifth most important cereal in the world and a staple food for humans. It is also a source of food and fodder for animals. In addition to the abiotic stresses such as drought, parasitic weeds of the genus Striga cause losses in sorghum production in sub Saharan Africa. Striga asiatica is a parasitic weed that attacks cereals in low input agricultural systems and is distributed throughout semi- arid regions of Africa. Most sorghum producing farmers rely on tolerance for their harvests in Striga infested fields yet the stability of tolerance in the face of a changing climate (recurrent droughts), new farming systems (mulch based agriculture) and existence of various Striga strains needs further investigation. Reduced strigolactones production was also studied as a resistance mechanism. The first study was focused on the determination of tolerance of Striga asiatica infested sorghum under drought in a pot study. Five sorghum lines were subjected to infestation with Striga and some were not infested while watering was done at 50 percent field capacity (FC) and 100 percent FC. The results showed that the five sorghum lines differed significantly in chlorophyll content and Normalised Differential Vegetation Index (NDVI). Infection did not lower chlorophyll content when it co-occurred with drought across all sorghum lines. Drought and infestation had mutually exclusive effects on chlorophyll content and NDVI. Under infestation, internode length was similar both at 100 percent FC and at 50 percent FC while under uninfested conditions, 100 percent FC gave the longer internode compared to 50 percent FC. Both infestation and irrigation regime reduced the sorghum head weight, illustrating that the two effects have synergistic effects on sorghum head weight. The second study sought to determine the effects of mulching and infestation on sorghum spp tolerance to Striga asiatica. The experiments were carried out in the seasons 2013/14 and 2014/15 summer seasons. The results indicated that mulching increased chlorophyll content in the 2014/15 season which was a drier season compared to 2013/14. In the 2014/15 season, mulching increased chlorophyll content in all varieties except Ruzangwaya, Mukadziusaende and SC Sila. When the same varieties were infested under mulch and infested without mulch, the results showed that mulching overcomes the effects of infestation in some varieties. Mulch also negates the effect of Striga parasitism and results in yield maintenance in sorghum varieties. The third study sought to determine the stability of sorghum lines when exposed to two Striga asiatica lines sourced from two places which are 500 km apart in Zimbabwe. The two strains were termed the Chiundura and Rushinga strains, based on where they were sourced. The experiments were conducted at Henderson Research Station (HRS) at Mazoe and at Bindura University of Science Education (BUSE). The results showed differential virulence for some traits while the two strains were equally virulent for some traits. The two strains were equally virulent on all sorghum lines with respect to chlorophyll content. The different sorghum lines responded differently to the effects of the two strains. The effects of the two strains were generally similar for head index, root index, and leaf index at all sites. Generally the Chiundura strain was more virulent to sorghum lines compared to Rushinga strain, confirming the existence of physiological strains of Striga in Zimbabwe. Therefore physiological speciation of Striga asiatica exists and this adds a further dimension to the complexity of Striga management in the smallholder sector. Quantification of strigolactone production by different sorghum genotypes was conducted in the laboratory using the agar gel assay. The genotype Mukadziusaende produced significantly the least (P<0.01) quantities of strigolactones, as inferred from the maximum germination distance (MGD) from the sorghum root. The MGD was negatively correlated to tiller numbers illustrating that the more the strigolactones the less the tillering capacity. Tiller numbers and MGD can therefore be used to select for reduced strigolactones production.
- Full Text:
- Date Issued: 2017
- Authors: Mandumbu, Ronald
- Date: 2017
- Subjects: Sorghum Sorghum -- Drought tolerance Sorghum -- Effect of drought on
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2788 , vital:28088
- Description: Sorghum is the fifth most important cereal in the world and a staple food for humans. It is also a source of food and fodder for animals. In addition to the abiotic stresses such as drought, parasitic weeds of the genus Striga cause losses in sorghum production in sub Saharan Africa. Striga asiatica is a parasitic weed that attacks cereals in low input agricultural systems and is distributed throughout semi- arid regions of Africa. Most sorghum producing farmers rely on tolerance for their harvests in Striga infested fields yet the stability of tolerance in the face of a changing climate (recurrent droughts), new farming systems (mulch based agriculture) and existence of various Striga strains needs further investigation. Reduced strigolactones production was also studied as a resistance mechanism. The first study was focused on the determination of tolerance of Striga asiatica infested sorghum under drought in a pot study. Five sorghum lines were subjected to infestation with Striga and some were not infested while watering was done at 50 percent field capacity (FC) and 100 percent FC. The results showed that the five sorghum lines differed significantly in chlorophyll content and Normalised Differential Vegetation Index (NDVI). Infection did not lower chlorophyll content when it co-occurred with drought across all sorghum lines. Drought and infestation had mutually exclusive effects on chlorophyll content and NDVI. Under infestation, internode length was similar both at 100 percent FC and at 50 percent FC while under uninfested conditions, 100 percent FC gave the longer internode compared to 50 percent FC. Both infestation and irrigation regime reduced the sorghum head weight, illustrating that the two effects have synergistic effects on sorghum head weight. The second study sought to determine the effects of mulching and infestation on sorghum spp tolerance to Striga asiatica. The experiments were carried out in the seasons 2013/14 and 2014/15 summer seasons. The results indicated that mulching increased chlorophyll content in the 2014/15 season which was a drier season compared to 2013/14. In the 2014/15 season, mulching increased chlorophyll content in all varieties except Ruzangwaya, Mukadziusaende and SC Sila. When the same varieties were infested under mulch and infested without mulch, the results showed that mulching overcomes the effects of infestation in some varieties. Mulch also negates the effect of Striga parasitism and results in yield maintenance in sorghum varieties. The third study sought to determine the stability of sorghum lines when exposed to two Striga asiatica lines sourced from two places which are 500 km apart in Zimbabwe. The two strains were termed the Chiundura and Rushinga strains, based on where they were sourced. The experiments were conducted at Henderson Research Station (HRS) at Mazoe and at Bindura University of Science Education (BUSE). The results showed differential virulence for some traits while the two strains were equally virulent for some traits. The two strains were equally virulent on all sorghum lines with respect to chlorophyll content. The different sorghum lines responded differently to the effects of the two strains. The effects of the two strains were generally similar for head index, root index, and leaf index at all sites. Generally the Chiundura strain was more virulent to sorghum lines compared to Rushinga strain, confirming the existence of physiological strains of Striga in Zimbabwe. Therefore physiological speciation of Striga asiatica exists and this adds a further dimension to the complexity of Striga management in the smallholder sector. Quantification of strigolactone production by different sorghum genotypes was conducted in the laboratory using the agar gel assay. The genotype Mukadziusaende produced significantly the least (P<0.01) quantities of strigolactones, as inferred from the maximum germination distance (MGD) from the sorghum root. The MGD was negatively correlated to tiller numbers illustrating that the more the strigolactones the less the tillering capacity. Tiller numbers and MGD can therefore be used to select for reduced strigolactones production.
- Full Text:
- Date Issued: 2017
Characterisation of the production and consumption of milk in the communal livestock production sector of the Eastern Cape Province, South Africa
- Authors: Kumbirai, Kaguru Tinashe
- Date: 2016
- Subjects: Milk consumption -- South Africa -- Eastern Cape Dairy farming -- Economic aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/3066 , vital:28251
- Description: The study was conducted in Eastern Cape Province, South Africa with the objective of characterising milk production and consumption among the communal households. A pretested semi-structured questionnaire was used to collect data through a single visit survey between June 2014 and May 2015. The study was undertaken in five randomly selected communal districts using a multi – stage area probability sampling method. Household sample size was calculated using a statistical methodology through a fixed formula based on a rural population size of 4410000, at a confidence level of 95 percent. A total of 500 households were selected with a sample size of 20 households in 5 communities within five different communal districts within the province. Half of the total sample size was used to represent the number of non-milk producing households (250) to get a true reflection on consumption profiles for nonproducers. Across the province the average communal family size was between 5-10 members with a monthly income of ZAR1340 per household. On average, pasture land size of the sampled households was 1 ha, with a range of 0.25-1.7 ha. The numbers of animals per species found in the studied province was highest for sheep (310) followed by cattle (227) and goat (87). Average livestock holding per household in the study area was 9.85 TLU (Tropical Livestock Unit). According to the respondents the predominant milking livestock numbers were between 1-3 animals milking per household. In the studied area traditional hand milking of livestock was the major milking practices at 12 percent in goats, 15 percent in sheep and 45 percent in cattle milk production. Consumption was the predominant reason for milk production recorded at 27 percent across the province. Milk production was 43 percent most preferred in cattle followed by 32 percent in goat and least at 29 percent in sheep across the province. In general, from the study it was noted that the majority (38 percent) of the respondents across the province indicated 0-5mins as the time it took to milk most milk producing livestock. The majority of the milking practices was done (37 percent) predominantly once a day, followed by 2 percent twice daily across the province. The daily milk production was on average (0.45±1.07) 2-5 litre in cattle, (4.86±0.814) 0-1litre in goats and (2.62±0.42) 0-1 litre sheep per producing house hold with in the province The monthly raw milk consumption in the province was (2.20± 1.42) 2-5 litres of cattle milk, (4.78±0.79) 2-5 litres of goat milk and (4.98±0.69) 2-5 litres of sheep milk per consuming household.
- Full Text:
- Date Issued: 2016
- Authors: Kumbirai, Kaguru Tinashe
- Date: 2016
- Subjects: Milk consumption -- South Africa -- Eastern Cape Dairy farming -- Economic aspects -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/3066 , vital:28251
- Description: The study was conducted in Eastern Cape Province, South Africa with the objective of characterising milk production and consumption among the communal households. A pretested semi-structured questionnaire was used to collect data through a single visit survey between June 2014 and May 2015. The study was undertaken in five randomly selected communal districts using a multi – stage area probability sampling method. Household sample size was calculated using a statistical methodology through a fixed formula based on a rural population size of 4410000, at a confidence level of 95 percent. A total of 500 households were selected with a sample size of 20 households in 5 communities within five different communal districts within the province. Half of the total sample size was used to represent the number of non-milk producing households (250) to get a true reflection on consumption profiles for nonproducers. Across the province the average communal family size was between 5-10 members with a monthly income of ZAR1340 per household. On average, pasture land size of the sampled households was 1 ha, with a range of 0.25-1.7 ha. The numbers of animals per species found in the studied province was highest for sheep (310) followed by cattle (227) and goat (87). Average livestock holding per household in the study area was 9.85 TLU (Tropical Livestock Unit). According to the respondents the predominant milking livestock numbers were between 1-3 animals milking per household. In the studied area traditional hand milking of livestock was the major milking practices at 12 percent in goats, 15 percent in sheep and 45 percent in cattle milk production. Consumption was the predominant reason for milk production recorded at 27 percent across the province. Milk production was 43 percent most preferred in cattle followed by 32 percent in goat and least at 29 percent in sheep across the province. In general, from the study it was noted that the majority (38 percent) of the respondents across the province indicated 0-5mins as the time it took to milk most milk producing livestock. The majority of the milking practices was done (37 percent) predominantly once a day, followed by 2 percent twice daily across the province. The daily milk production was on average (0.45±1.07) 2-5 litre in cattle, (4.86±0.814) 0-1litre in goats and (2.62±0.42) 0-1 litre sheep per producing house hold with in the province The monthly raw milk consumption in the province was (2.20± 1.42) 2-5 litres of cattle milk, (4.78±0.79) 2-5 litres of goat milk and (4.98±0.69) 2-5 litres of sheep milk per consuming household.
- Full Text:
- Date Issued: 2016
Measuring changes in residential segregation in Port Elizabeth, South Africa, from 1996-2011
- Authors: Odayar, Luveshni
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3641 , vital:20532
- Description: Racial segregation and inequality were the prime objectives of the colonial and apartheid spatial planning policies that governed the spatial development of the South African urban landscape. Since South Africa’s democratic transition after 1994, efforts have been made by government to facilitate racial integration and transform the apartheid urban fabric. Research into post-apartheid segregation is crucial to assess the success of governmental actions enacted thus far, while informing future spatial planning strategies. Most studies of these processes have relied solely on dichotomous indices to measure the extent of segregation between two groups. Few have utilized multi-group indices, which are more suited to investigating changes in multi-ethnic cases. Furthermore, the segregation indices used are typically aspatial. This study investigates the extent to which the segregationist legacy prevails in Port Elizabeth, a place widely considered to be the founding city of urban racial segregation. It also aims to investigate the impact of geographical scale on segregation. Theil’s multi-group Entropy Index and Duncan and Duncan’s Dissimilarity Index were derived from racial population data from the 1996, 2001 and 2011 National Censuses, and GIS was used to map changes in racial diversity both at tract level and across a range of geographical scales. To generate a more holistic understanding of the observed trends, statistical tests were performed to relate the observed patterns to socio-economic determinants, and feedback from the relevant government department was obtained. The results from the entropy indices reveal that segregation levels in Port Elizabeth have declined but still remain high: 84.6 % (1996), 79.2 % (2001) to 71.5 % (2011). This is a similar trend to those found in Cape Town and Johannesburg. The integration that did occur was characterized by one-way patterns of movement into former-White areas; this was predominantly confined to the Indian population, and to a lesser extent, the Coloured population. The vast majority of the African population remains confined to their former designated location areas. The White population remains the most segregated group, despite most of the racial integration occurring in former-White areas. Interview results and statistical tests revealed that persisting racial discrepancies in socio-economic factors (income, employment and education) can be considered major drivers influencing the observed trends in racial integration and persisting desegregation, as well as self-segregation.
- Full Text:
- Date Issued: 2016
- Authors: Odayar, Luveshni
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3641 , vital:20532
- Description: Racial segregation and inequality were the prime objectives of the colonial and apartheid spatial planning policies that governed the spatial development of the South African urban landscape. Since South Africa’s democratic transition after 1994, efforts have been made by government to facilitate racial integration and transform the apartheid urban fabric. Research into post-apartheid segregation is crucial to assess the success of governmental actions enacted thus far, while informing future spatial planning strategies. Most studies of these processes have relied solely on dichotomous indices to measure the extent of segregation between two groups. Few have utilized multi-group indices, which are more suited to investigating changes in multi-ethnic cases. Furthermore, the segregation indices used are typically aspatial. This study investigates the extent to which the segregationist legacy prevails in Port Elizabeth, a place widely considered to be the founding city of urban racial segregation. It also aims to investigate the impact of geographical scale on segregation. Theil’s multi-group Entropy Index and Duncan and Duncan’s Dissimilarity Index were derived from racial population data from the 1996, 2001 and 2011 National Censuses, and GIS was used to map changes in racial diversity both at tract level and across a range of geographical scales. To generate a more holistic understanding of the observed trends, statistical tests were performed to relate the observed patterns to socio-economic determinants, and feedback from the relevant government department was obtained. The results from the entropy indices reveal that segregation levels in Port Elizabeth have declined but still remain high: 84.6 % (1996), 79.2 % (2001) to 71.5 % (2011). This is a similar trend to those found in Cape Town and Johannesburg. The integration that did occur was characterized by one-way patterns of movement into former-White areas; this was predominantly confined to the Indian population, and to a lesser extent, the Coloured population. The vast majority of the African population remains confined to their former designated location areas. The White population remains the most segregated group, despite most of the racial integration occurring in former-White areas. Interview results and statistical tests revealed that persisting racial discrepancies in socio-economic factors (income, employment and education) can be considered major drivers influencing the observed trends in racial integration and persisting desegregation, as well as self-segregation.
- Full Text:
- Date Issued: 2016
Understanding how grade 11 Physical Science teachers mediate learning of the topic distillation in the Kavango Region
- Authors: Shifafure, Andreas Muronga
- Date: 2015
- Subjects: Science -- Study and teaching (Secondary) -- Namibia -- Kavango , Distillation -- Study and teaching (Secondary) -- Namibia -- Kavango , Teachers -- Training of -- Namibia -- Kavango , Community and school -- Namibia -- Kavango , Interdisciplinary approach to knowledge
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2046 , http://hdl.handle.net/10962/d1017357
- Description: The National Curriculum of Education was implemented with the broad view of including all learners as laid out in the document Toward Education for All. The curriculum emphasised that the topic distillation should be studied. According to the Examiners Reports, the topic distillation is one of the topics where learners face difficulties in the Namibian Senior Secondary Certificate Ordinary (NSSCO) examination Grade 12. This led me to do research on understanding how Physical Science teachers mediate the topic distillation in Namibia specifically in the Kavango region. The study was carried out at two rural schools with two teachers teaching Grade 11. The community member who I asked to demonstrate the making of Kashipembe was also a participant during this study. Kashipembe is a local cultural brew alcohol beverage commonly made in the Kavango East and West Regions of Namibia, which was used as a learning context in this research study. The study used a qualitative case study underpinned by an interpretive paradigm. Data was generated through the use of document analysis, semi-structured interviews, stimulated recall interviews, lesson observations, brainstorming and practical demonstration of making Kashipembe. These different methods of data gathering were used with the aim of triangulating and validating the data. Therefore, my theoretical framework adopted Vygotsky’s (1986) mediation of learning, social constructivism and pedagogical content knowledge according to Shulman’s (1986) theory. The emergent themes were identified inductively and they were colour coded. These themes were later developed into analytic statements which were used in the study. The findings indicate that the use of community knowledge and experience during the teaching of scientific concepts like distillation is important. These findings can also be used by the practising teachers to make their teaching more effective in the curriculums where distillation is included. Therefore, the Namibian curriculum developers need to include this community knowledge in the curriculum to make it easier for the learners to make sense of the topic distillation.
- Full Text:
- Date Issued: 2015
- Authors: Shifafure, Andreas Muronga
- Date: 2015
- Subjects: Science -- Study and teaching (Secondary) -- Namibia -- Kavango , Distillation -- Study and teaching (Secondary) -- Namibia -- Kavango , Teachers -- Training of -- Namibia -- Kavango , Community and school -- Namibia -- Kavango , Interdisciplinary approach to knowledge
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:2046 , http://hdl.handle.net/10962/d1017357
- Description: The National Curriculum of Education was implemented with the broad view of including all learners as laid out in the document Toward Education for All. The curriculum emphasised that the topic distillation should be studied. According to the Examiners Reports, the topic distillation is one of the topics where learners face difficulties in the Namibian Senior Secondary Certificate Ordinary (NSSCO) examination Grade 12. This led me to do research on understanding how Physical Science teachers mediate the topic distillation in Namibia specifically in the Kavango region. The study was carried out at two rural schools with two teachers teaching Grade 11. The community member who I asked to demonstrate the making of Kashipembe was also a participant during this study. Kashipembe is a local cultural brew alcohol beverage commonly made in the Kavango East and West Regions of Namibia, which was used as a learning context in this research study. The study used a qualitative case study underpinned by an interpretive paradigm. Data was generated through the use of document analysis, semi-structured interviews, stimulated recall interviews, lesson observations, brainstorming and practical demonstration of making Kashipembe. These different methods of data gathering were used with the aim of triangulating and validating the data. Therefore, my theoretical framework adopted Vygotsky’s (1986) mediation of learning, social constructivism and pedagogical content knowledge according to Shulman’s (1986) theory. The emergent themes were identified inductively and they were colour coded. These themes were later developed into analytic statements which were used in the study. The findings indicate that the use of community knowledge and experience during the teaching of scientific concepts like distillation is important. These findings can also be used by the practising teachers to make their teaching more effective in the curriculums where distillation is included. Therefore, the Namibian curriculum developers need to include this community knowledge in the curriculum to make it easier for the learners to make sense of the topic distillation.
- Full Text:
- Date Issued: 2015
The ecology and management of the large carnivore guild on Shamwari Game Reserve, Eastern Cape
- Authors: O'Brien, John William
- Date: 2013
- Subjects: Cheetah -- Behavior -- South Africa -- Shamwari Game Reserve Shamwari Game Reserve (South Africa) Carnivora -- South Africa -- Shamwari Game Reserve Wildlife conservation -- South Africa -- Shamwari Game Reserve Game reserves -- Management -- South Africa -- Shamwari Game Reserve Lion -- Behavior -- South Africa -- Shamwari Game Reserve Lion -- Ecology -- South Africa -- Shamwari Game Reserve African wild dog -- Ecology -- South Africa -- Shamwari Game Reserve Cheetah -- Ecology -- South Africa -- Shamwari Game Reserve Lion -- Food -- South Africa -- Shamwari Game Reserve Lion -- Food -- South Africa -- Shamwari Game Reserve Cheetah -- Food -- South Africa -- Shamwari Game Reserve African wild dog -- Behavior -- South Africa -- Shamwari Game Reserve African wild dog -- Food -- South Africa -- Shamwari Game Reserve Leopard -- Behavior -- South Africa -- Shamwari Game Reserve Leopard -- Ecology -- South Africa -- Shamwari Game Reserve Leopard -- Food --South Africa -- Shamwari Game Reserve
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5609 , http://hdl.handle.net/10962/d1002604
- Description: Shamwari Game Reserve was the first enclosed conservation area in the Eastern Cape Province of South Africa to reintroduce free ranging lions, cheetahs, leopards and wild dogs back into their historic range. At that time (2000 – 2001), little information was available on the ecology and behaviour of these predators in the habitats of the Eastern Cape, and management decisions were based on assumptions and unfounded comparisons with extant populations but from quite different habitats. The aim of this study was therefore to obtain a better understanding of the feeding ecology and space use of the predator guild, and the carrying capacity of Shamwari Game Reserve to enable more informed management decisions. In addition, the reserve is a photographic based tourism venture and understanding both the ecological and financial sustainability of the predator guild was important. The diets of the predators were similar to those reported in other studies; larger predators killed a greater range of prey species than did smaller predators and a small number of prey species made up the majority of the kills. The larger predators had a higher mean kill mass than the smaller species and prey selection was influenced by prey size, prey abundance and prey habitat preference, and risk associated with hunting the species. Diet was flexible and responded to natural and management induced changes in prey abundance. There was a considerable overlap in space use by the lions, cheetahs and leopards with their core areas being centred on and around the Bushmans River. Space use was driven by resource distribution and landscape attributes, and by the presence of other predators of the same or different species. The long term viability of wild dog within the reserve was explored and the results confirmed that there was neither the required space nor the ecological processes and the wild dogs were removed from the reserve. A carrying capacity of the reserve for the predator guild was determined using the Maximum Sustainable Yield method to assess the potential prey species off take and a resultant density of 3.3 to 6.6 lion female equivalent units per 10 000 ha was established. The natural carrying capacity of the reserve with respect to predators will not sustain the tourism objectives and consequently prey supplementation was necessary to maintain predator density at levels high enough to sustain tourism. Under these conditions the large predator guild is still sustainable financially although careful, responsible management is needed to provide ecological sustainability.
- Full Text:
- Date Issued: 2013
- Authors: O'Brien, John William
- Date: 2013
- Subjects: Cheetah -- Behavior -- South Africa -- Shamwari Game Reserve Shamwari Game Reserve (South Africa) Carnivora -- South Africa -- Shamwari Game Reserve Wildlife conservation -- South Africa -- Shamwari Game Reserve Game reserves -- Management -- South Africa -- Shamwari Game Reserve Lion -- Behavior -- South Africa -- Shamwari Game Reserve Lion -- Ecology -- South Africa -- Shamwari Game Reserve African wild dog -- Ecology -- South Africa -- Shamwari Game Reserve Cheetah -- Ecology -- South Africa -- Shamwari Game Reserve Lion -- Food -- South Africa -- Shamwari Game Reserve Lion -- Food -- South Africa -- Shamwari Game Reserve Cheetah -- Food -- South Africa -- Shamwari Game Reserve African wild dog -- Behavior -- South Africa -- Shamwari Game Reserve African wild dog -- Food -- South Africa -- Shamwari Game Reserve Leopard -- Behavior -- South Africa -- Shamwari Game Reserve Leopard -- Ecology -- South Africa -- Shamwari Game Reserve Leopard -- Food --South Africa -- Shamwari Game Reserve
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5609 , http://hdl.handle.net/10962/d1002604
- Description: Shamwari Game Reserve was the first enclosed conservation area in the Eastern Cape Province of South Africa to reintroduce free ranging lions, cheetahs, leopards and wild dogs back into their historic range. At that time (2000 – 2001), little information was available on the ecology and behaviour of these predators in the habitats of the Eastern Cape, and management decisions were based on assumptions and unfounded comparisons with extant populations but from quite different habitats. The aim of this study was therefore to obtain a better understanding of the feeding ecology and space use of the predator guild, and the carrying capacity of Shamwari Game Reserve to enable more informed management decisions. In addition, the reserve is a photographic based tourism venture and understanding both the ecological and financial sustainability of the predator guild was important. The diets of the predators were similar to those reported in other studies; larger predators killed a greater range of prey species than did smaller predators and a small number of prey species made up the majority of the kills. The larger predators had a higher mean kill mass than the smaller species and prey selection was influenced by prey size, prey abundance and prey habitat preference, and risk associated with hunting the species. Diet was flexible and responded to natural and management induced changes in prey abundance. There was a considerable overlap in space use by the lions, cheetahs and leopards with their core areas being centred on and around the Bushmans River. Space use was driven by resource distribution and landscape attributes, and by the presence of other predators of the same or different species. The long term viability of wild dog within the reserve was explored and the results confirmed that there was neither the required space nor the ecological processes and the wild dogs were removed from the reserve. A carrying capacity of the reserve for the predator guild was determined using the Maximum Sustainable Yield method to assess the potential prey species off take and a resultant density of 3.3 to 6.6 lion female equivalent units per 10 000 ha was established. The natural carrying capacity of the reserve with respect to predators will not sustain the tourism objectives and consequently prey supplementation was necessary to maintain predator density at levels high enough to sustain tourism. Under these conditions the large predator guild is still sustainable financially although careful, responsible management is needed to provide ecological sustainability.
- Full Text:
- Date Issued: 2013
Male and female cardiovascular risk in an urban, black working population
- Authors: Jackson, Lindsay May
- Date: 2011
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5127 , http://hdl.handle.net/10962/d1005205 , Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Description: The aim of this research project was to assess and compare cardiovascular disease (CVD) risk in black males and females from an urban, working population in the Makana (Grahamstown) region of the Eastern Cape, South Africa. Two-hundred and ninety one individuals (males: n = 143, females: n = 148) with a mean age of 42.6 (±8.1) years were voluntarily recruited from the greater urban Makana (Grahamstown) area. Eight Cardiovascular disease (CVD) risks were assessed: stature and mass were obtained in order to calculate body mass index (BMI) (mass/stature2). Obesity, defined as a morphological risk, was classified according to the World Health Organisation (WHO) BMI criteria (BMI>30kg.m-2), as well as according to measures of waist circumference (WC) and body composition. Hypertension, hypercholesterolemia and type II diabetes, were grouped as cardiovascular (CV) risks. Hypertension was defined as a blood pressure greater than 140/90mmHg (JNC-7); hypercholesterolemia, as total cholesterol greater than 6.2mmol.L-1 (NCEP); and type II diabetes, as total glucose greater than 12mmol.L-1 (WHO). Physical activity, diet, tobacco use, and alcohol consumption and dependence were grouped as lifestyle-related risks. These were assessed by means of self-reporting through the use of various validated questionnaires. Finally, self-reporting of obesity, hypertension, hypercholesterolemia and type II diabetes was assessed, in addition to perception questions on individuals’ perceived body shape and size (Ziebland figures). Self-reported and perceived responses were then compared to actual measures. Females were significantly (p<0.001) heavier than the males (92.7kg compared to 72.1kg) and had significantly (p<0.001) higher BMIs than their male counterparts (37.6kg.m-2 compared to 25.7 kg.-2). They also recorded significantly (p<0.001) higher waist circumference (WC) values and had significantly (p<0.001) higher percentage and total body fat. Significantly (p<0.001) more females were obese (81%) compared to males (17%). While a higher percentage of males (25 % compared to 22%) presented with stage I hypertension (≥140/90mmHg, <160/95mmHg), significantly (p<0.05) more females (14% compared to 8%) presented with stage II hypertension (>160/95mmHg). The prevalence of hypercholesterolemia at a high level of risk (>6.2mmol.L-1) was relatively low (2.1 % of males, 3.4% of females), but notably more participants (22% of males and 26% of females) presented with the condition at a moderate level of risk (>5mmol.L-1). Type II diabetes was the least prevalent CV risk factor, with no males and only 3% of females presenting with the condition. Males consumed significantly (p<0.05) more in terms of total energy intake (9024 vs. 7234 kJ) and were significantly (p<0.05) more active (3315 compared to 2660 MET-mins.week). A significantly (p<0.05) higher percentage of males smoked (51.1% compared to 3.4%), consumed alcohol (73.4% compared to 46.6%) and were alcohol dependent (40% compared to 33.5%). Both males and females tended to be ignorant of their health status, with both samples under-reporting obesity, hypertension and hypercholesterolemia, while over-reporting type II diabetes. Furthermore, obesity was significantly (p<0.05) underestimated, with both male and female individuals perceiving themselves to be notably smaller than they actually were. Physical activity and diet were important determinants of CVD risk in this black urban sample of individuals. Obesity, in particular central adiposity, was the most notable risk (particularly in females), followed by hypertension (particularly in males). Although some risks presented at a moderate level of risk, a clustering of risk factors was evident in both samples, with 12.6% and 41.2% of males and females presenting with two risk factors, and 2.8% and 8.1% of males and females respectively presenting with three risks.
- Full Text:
- Date Issued: 2011
- Authors: Jackson, Lindsay May
- Date: 2011
- Subjects: Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5127 , http://hdl.handle.net/10962/d1005205 , Cardiovascular system -- Diseases -- South Africa -- Grahamstown , Obesity -- South Africa -- Grahamstown , Hypertension -- South Africa -- Grahamstown , Hypercholesteremia -- South Africa -- Grahamstown , Diabetes -- South Africa -- Grahamstown , Lifestyles -- Health aspects -- South Africa -- Grahamstown , Health behavior -- South Africa -- Grahamstown , Health attitudes -- South Africa -- Grahamstown , Black people -- South Africa -- Grahamstown -- Health and hygiene
- Description: The aim of this research project was to assess and compare cardiovascular disease (CVD) risk in black males and females from an urban, working population in the Makana (Grahamstown) region of the Eastern Cape, South Africa. Two-hundred and ninety one individuals (males: n = 143, females: n = 148) with a mean age of 42.6 (±8.1) years were voluntarily recruited from the greater urban Makana (Grahamstown) area. Eight Cardiovascular disease (CVD) risks were assessed: stature and mass were obtained in order to calculate body mass index (BMI) (mass/stature2). Obesity, defined as a morphological risk, was classified according to the World Health Organisation (WHO) BMI criteria (BMI>30kg.m-2), as well as according to measures of waist circumference (WC) and body composition. Hypertension, hypercholesterolemia and type II diabetes, were grouped as cardiovascular (CV) risks. Hypertension was defined as a blood pressure greater than 140/90mmHg (JNC-7); hypercholesterolemia, as total cholesterol greater than 6.2mmol.L-1 (NCEP); and type II diabetes, as total glucose greater than 12mmol.L-1 (WHO). Physical activity, diet, tobacco use, and alcohol consumption and dependence were grouped as lifestyle-related risks. These were assessed by means of self-reporting through the use of various validated questionnaires. Finally, self-reporting of obesity, hypertension, hypercholesterolemia and type II diabetes was assessed, in addition to perception questions on individuals’ perceived body shape and size (Ziebland figures). Self-reported and perceived responses were then compared to actual measures. Females were significantly (p<0.001) heavier than the males (92.7kg compared to 72.1kg) and had significantly (p<0.001) higher BMIs than their male counterparts (37.6kg.m-2 compared to 25.7 kg.-2). They also recorded significantly (p<0.001) higher waist circumference (WC) values and had significantly (p<0.001) higher percentage and total body fat. Significantly (p<0.001) more females were obese (81%) compared to males (17%). While a higher percentage of males (25 % compared to 22%) presented with stage I hypertension (≥140/90mmHg, <160/95mmHg), significantly (p<0.05) more females (14% compared to 8%) presented with stage II hypertension (>160/95mmHg). The prevalence of hypercholesterolemia at a high level of risk (>6.2mmol.L-1) was relatively low (2.1 % of males, 3.4% of females), but notably more participants (22% of males and 26% of females) presented with the condition at a moderate level of risk (>5mmol.L-1). Type II diabetes was the least prevalent CV risk factor, with no males and only 3% of females presenting with the condition. Males consumed significantly (p<0.05) more in terms of total energy intake (9024 vs. 7234 kJ) and were significantly (p<0.05) more active (3315 compared to 2660 MET-mins.week). A significantly (p<0.05) higher percentage of males smoked (51.1% compared to 3.4%), consumed alcohol (73.4% compared to 46.6%) and were alcohol dependent (40% compared to 33.5%). Both males and females tended to be ignorant of their health status, with both samples under-reporting obesity, hypertension and hypercholesterolemia, while over-reporting type II diabetes. Furthermore, obesity was significantly (p<0.05) underestimated, with both male and female individuals perceiving themselves to be notably smaller than they actually were. Physical activity and diet were important determinants of CVD risk in this black urban sample of individuals. Obesity, in particular central adiposity, was the most notable risk (particularly in females), followed by hypertension (particularly in males). Although some risks presented at a moderate level of risk, a clustering of risk factors was evident in both samples, with 12.6% and 41.2% of males and females presenting with two risk factors, and 2.8% and 8.1% of males and females respectively presenting with three risks.
- Full Text:
- Date Issued: 2011
Breaking down subtle and implicit racial divides in higher education institutions : an educational management perspective
- Toni, Mademoiselle Noluthando
- Authors: Toni, Mademoiselle Noluthando
- Date: 2009
- Subjects: Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9529 , http://hdl.handle.net/10948/876 , Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Description: This thesis examined the manifestations of the various forms of racism in a South African institution of higher learning, the Nelson Mandela Metropolitan University (NMMU). The study further attempted to confront racism from the perspective of finding ways in which human relations of a diversified higher education population could be improved. As the issue at hand in this study relates to racism, critical race theory (CRT) was explored in an attempt to understand different perceptions and ways of dealing with racial inequality. CRT recognizes the complexities of racism and the construction of race as a way of justifying political, economic and social inequality (Stovall, 2006:247). This understanding played a role in making sense of perceived racial discrimination which is also connected to gender, age and social class. CRT conceptual tools, such as stories and counter stories featured strongly in the data collection process. Understanding the relationships of power, race and racism, as advocated by CRT, was vital in the process of analyzing data, reporting on the findings, and the proposed recommendations. The empirical data and literature provided insight in the design of a ‘Wheel of Humanity’ which serves as a succinct portrayal of ideas that can work in nurturing acceptable, to better, human relations. The study revealed that Meta-stereotypes influenced the perceptions of racist attitudes, behaviours and practices. As much as overt forms of racism were reported as minimal, subtle and implicit forms still exist, and are aggravated by the ‘culture of power’ that is taken for granted. The success of initiatives designed for the purposes of going beyond race, and adopting a humane approach in instilling the principles of ubuntu, depends on changing attitudes and preconceived ideas.
- Full Text:
- Date Issued: 2009
- Authors: Toni, Mademoiselle Noluthando
- Date: 2009
- Subjects: Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9529 , http://hdl.handle.net/10948/876 , Racism in higher education -- South Africa -- Port Elizabeth , Educational change -- South Africa -- Port Elizabeth
- Description: This thesis examined the manifestations of the various forms of racism in a South African institution of higher learning, the Nelson Mandela Metropolitan University (NMMU). The study further attempted to confront racism from the perspective of finding ways in which human relations of a diversified higher education population could be improved. As the issue at hand in this study relates to racism, critical race theory (CRT) was explored in an attempt to understand different perceptions and ways of dealing with racial inequality. CRT recognizes the complexities of racism and the construction of race as a way of justifying political, economic and social inequality (Stovall, 2006:247). This understanding played a role in making sense of perceived racial discrimination which is also connected to gender, age and social class. CRT conceptual tools, such as stories and counter stories featured strongly in the data collection process. Understanding the relationships of power, race and racism, as advocated by CRT, was vital in the process of analyzing data, reporting on the findings, and the proposed recommendations. The empirical data and literature provided insight in the design of a ‘Wheel of Humanity’ which serves as a succinct portrayal of ideas that can work in nurturing acceptable, to better, human relations. The study revealed that Meta-stereotypes influenced the perceptions of racist attitudes, behaviours and practices. As much as overt forms of racism were reported as minimal, subtle and implicit forms still exist, and are aggravated by the ‘culture of power’ that is taken for granted. The success of initiatives designed for the purposes of going beyond race, and adopting a humane approach in instilling the principles of ubuntu, depends on changing attitudes and preconceived ideas.
- Full Text:
- Date Issued: 2009
An evaluation of IMF structural adjustment programmes : lessons for South Africa
- Authors: Berolsky, Nuno Goncalo
- Date: 2000
- Subjects: International Monetary Fund , International Monetary Fund -- Developing countries , Structural adjustment (Economic policy) -- Developing countries , South Africa -- Economic policy
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:935 , http://hdl.handle.net/10962/d1002668 , International Monetary Fund , International Monetary Fund -- Developing countries , Structural adjustment (Economic policy) -- Developing countries , South Africa -- Economic policy
- Description: The mixed results of International Monetary Fund structural adjustment programmes in less developed countries are a major motivation for this research. Explanations must be advanced as to what may inhibit the success of such programmes. South Africa has often found itself in a precarious position- with a deteriorating balance of payments, a position similar to other countries that have accepted IMF loans. Furthermore, South Africa undertook an IMF loan in 1993. Financial support from the IMF incorporates structural adjustment programmes. These may include measures such as tighter monetary policy, reduction in the budget deficit, exchange rate devaluation and ceilings on domestic credit with increased interest rates (Ferguson, 1988). These policies illustrate the principle of ‘conditionality,’ whereby access to further loans is conditional on certain criteria being met, such as reduced budget deficits and inflation rates. The principle of conditionality has met with a great deal of criticism. Bacha (1987) and Dell (1982) argue that these aggregate demand-reducing conditions more often than not stagnate domestic economies, worsening the balance of payment and result in programme breakdowns. Essentially, they refer to the IMF conditions as ‘unrealistic.’ The IMF denies this, arguing that shortfalls are mainly due to a lack of political commitment to carry out its conditions (Winters, 1994). This issue of conditionality will be examined in detail, using three specific case studies. The aim of this study is to examine the characteristics of Brazil, Mexico and Zambia to see whether or not the IMF programmes were successful. Guidelines will be established for South African policy from these case studies. South Africa is trying to adjust to the competitiveness of the international economy. At the same time, the need for reconstruction and development exerts increasing pressures on the balance of payments. Guidelines are established for a successful economic adjustment for South Africa. The research concludes that South Africa is certainly in line for a successful transformation. The rigidities are not as extensive as has been the case in Brazil and Zambia. Institutionally, South Africa is sound. However there are still challenges in this area, such as export diversification and economic stability to attract foreign investment.
- Full Text:
- Date Issued: 2000
- Authors: Berolsky, Nuno Goncalo
- Date: 2000
- Subjects: International Monetary Fund , International Monetary Fund -- Developing countries , Structural adjustment (Economic policy) -- Developing countries , South Africa -- Economic policy
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:935 , http://hdl.handle.net/10962/d1002668 , International Monetary Fund , International Monetary Fund -- Developing countries , Structural adjustment (Economic policy) -- Developing countries , South Africa -- Economic policy
- Description: The mixed results of International Monetary Fund structural adjustment programmes in less developed countries are a major motivation for this research. Explanations must be advanced as to what may inhibit the success of such programmes. South Africa has often found itself in a precarious position- with a deteriorating balance of payments, a position similar to other countries that have accepted IMF loans. Furthermore, South Africa undertook an IMF loan in 1993. Financial support from the IMF incorporates structural adjustment programmes. These may include measures such as tighter monetary policy, reduction in the budget deficit, exchange rate devaluation and ceilings on domestic credit with increased interest rates (Ferguson, 1988). These policies illustrate the principle of ‘conditionality,’ whereby access to further loans is conditional on certain criteria being met, such as reduced budget deficits and inflation rates. The principle of conditionality has met with a great deal of criticism. Bacha (1987) and Dell (1982) argue that these aggregate demand-reducing conditions more often than not stagnate domestic economies, worsening the balance of payment and result in programme breakdowns. Essentially, they refer to the IMF conditions as ‘unrealistic.’ The IMF denies this, arguing that shortfalls are mainly due to a lack of political commitment to carry out its conditions (Winters, 1994). This issue of conditionality will be examined in detail, using three specific case studies. The aim of this study is to examine the characteristics of Brazil, Mexico and Zambia to see whether or not the IMF programmes were successful. Guidelines will be established for South African policy from these case studies. South Africa is trying to adjust to the competitiveness of the international economy. At the same time, the need for reconstruction and development exerts increasing pressures on the balance of payments. Guidelines are established for a successful economic adjustment for South Africa. The research concludes that South Africa is certainly in line for a successful transformation. The rigidities are not as extensive as has been the case in Brazil and Zambia. Institutionally, South Africa is sound. However there are still challenges in this area, such as export diversification and economic stability to attract foreign investment.
- Full Text:
- Date Issued: 2000
The effect of load carriage on selected metabolic and perceptual responses of military personnel
- Authors: Ramabhai, Leena I
- Date: 2000
- Subjects: Marching -- Physiological aspects , Military art and science , Marching -- Psychological aspects , Lifting and carrying
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5111 , http://hdl.handle.net/10962/d1005189
- Description: Taking a multi-disciplinary, integrated approach, the present study sought to examine selected physiological and psycho-physical parameters related to load carriage involving a 12 km march under military conditions. Military constraints hampered, but did not entirely inhibit the secondary aim of the study which concerned the effectiveness of relativising loads in order to normalise responses for all soldiers, irrespective of morphological diversity. Forty three subjects were measured in six groups using a test-retest experimental protocol. They were involved in a rest-broken 12 km march at 4 km.h⁻¹ under 40.5 kg absolute total load and under a relative load of 37% of body mass. Heart rates, ratings of perceived exertion (RPE) as well as area and intensity of discomfort were monitored for all subjects. Ten subjects were measured more extensively with regard to physiology using the Metamax, a portable ergospirometry system that provides all the data needed for a complete functional analysis of lung, heart, circulation and metabolic activity. Physiological responses (fc; fb; V̇T; V̇E; V̇O₂; EE; V̇CO₂; R; T°) indicated subjects were not severely physically taxed and that the loads imposed constituted a sub-maximal demand. Moreover, there appeared to be a limited cumulative effect over the 3.5 h. Data from the first and third hours were similar, while the significantly higher responses in the second hour reflected the challenge of the undulating terrain encountered during this section of the march. All responses during the Relative load conditions mirrored those of the Absolute load condition but, because the demands were less, the trends occurred at a reduced level. Furthermore, the reduction in inter-individual variability indicates that relativised load carriage tends to stress the soldiers in a more uniform manner. All "local" RPE responses were higher than "central" ratings, suggesting soldiers were in good cardiovascular condition and experienced marginally more strain in the lower limbs. There was increased perceived strain corresponding to the increase in gradient, with little cumulative effect over the three hours. The shoulders and feet were the two regions in which most discomfort was experienced; the shoulders being the worst area in the first hour and the feet being rated the worst after the third hour of marching. This study clearly demonstrates the probability of a significant improvement in mean combat-readiness following loaded marching by showing that, if loads are set at levels commensurate with individual capabilities to carry them without undue strain, unnecessary physical demands experienced by smaller, more gracile soldiers are reduced.
- Full Text:
- Date Issued: 2000
- Authors: Ramabhai, Leena I
- Date: 2000
- Subjects: Marching -- Physiological aspects , Military art and science , Marching -- Psychological aspects , Lifting and carrying
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5111 , http://hdl.handle.net/10962/d1005189
- Description: Taking a multi-disciplinary, integrated approach, the present study sought to examine selected physiological and psycho-physical parameters related to load carriage involving a 12 km march under military conditions. Military constraints hampered, but did not entirely inhibit the secondary aim of the study which concerned the effectiveness of relativising loads in order to normalise responses for all soldiers, irrespective of morphological diversity. Forty three subjects were measured in six groups using a test-retest experimental protocol. They were involved in a rest-broken 12 km march at 4 km.h⁻¹ under 40.5 kg absolute total load and under a relative load of 37% of body mass. Heart rates, ratings of perceived exertion (RPE) as well as area and intensity of discomfort were monitored for all subjects. Ten subjects were measured more extensively with regard to physiology using the Metamax, a portable ergospirometry system that provides all the data needed for a complete functional analysis of lung, heart, circulation and metabolic activity. Physiological responses (fc; fb; V̇T; V̇E; V̇O₂; EE; V̇CO₂; R; T°) indicated subjects were not severely physically taxed and that the loads imposed constituted a sub-maximal demand. Moreover, there appeared to be a limited cumulative effect over the 3.5 h. Data from the first and third hours were similar, while the significantly higher responses in the second hour reflected the challenge of the undulating terrain encountered during this section of the march. All responses during the Relative load conditions mirrored those of the Absolute load condition but, because the demands were less, the trends occurred at a reduced level. Furthermore, the reduction in inter-individual variability indicates that relativised load carriage tends to stress the soldiers in a more uniform manner. All "local" RPE responses were higher than "central" ratings, suggesting soldiers were in good cardiovascular condition and experienced marginally more strain in the lower limbs. There was increased perceived strain corresponding to the increase in gradient, with little cumulative effect over the three hours. The shoulders and feet were the two regions in which most discomfort was experienced; the shoulders being the worst area in the first hour and the feet being rated the worst after the third hour of marching. This study clearly demonstrates the probability of a significant improvement in mean combat-readiness following loaded marching by showing that, if loads are set at levels commensurate with individual capabilities to carry them without undue strain, unnecessary physical demands experienced by smaller, more gracile soldiers are reduced.
- Full Text:
- Date Issued: 2000
Investigation of the causative agents of the 1982 Gazankulu poliomyelitis outbreak, using four biochemical techniques
- Authors: Gibson, Katherine Margaret
- Date: 1989
- Subjects: Poliomyelitis -- Analysis , Poliomyelitis -- History -- South Africa , Poliomyelitis vaccine -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3878 , http://hdl.handle.net/10962/d1001612
- Description: Comparison of poliovirus strains was carried out to determine the origin of the virus in two isolates obtained during the 1982 outbreak of poliomyelitis in Gazankulu. Comparisons of the outbreak isolates with vaccine and wild-type strains of the same poliovirus type were carried out using four biochemical techniques. SDS-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional thin-layer chromatography (TLC) and reversed-phase high-performance liquid-chromatography (RP-HPLC) were used for comparing viral capsid proteins. Comparison of poliovirus strains at a genetic level was carried out using two-dimensional oligonucleotide mapping of viral RNA. Results showed the type 1 poliovirus isolate, 5061, to be a novel wild-type poliovirus. The type 2 isolate, 5068, was closely related to the poliovirus type 2 Sabin vaccine strain, P712. It was concluded that the intrinsic variability of poliovirus strains was responsible for the appearance of isolate 5068
- Full Text:
- Date Issued: 1989
- Authors: Gibson, Katherine Margaret
- Date: 1989
- Subjects: Poliomyelitis -- Analysis , Poliomyelitis -- History -- South Africa , Poliomyelitis vaccine -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3878 , http://hdl.handle.net/10962/d1001612
- Description: Comparison of poliovirus strains was carried out to determine the origin of the virus in two isolates obtained during the 1982 outbreak of poliomyelitis in Gazankulu. Comparisons of the outbreak isolates with vaccine and wild-type strains of the same poliovirus type were carried out using four biochemical techniques. SDS-polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional thin-layer chromatography (TLC) and reversed-phase high-performance liquid-chromatography (RP-HPLC) were used for comparing viral capsid proteins. Comparison of poliovirus strains at a genetic level was carried out using two-dimensional oligonucleotide mapping of viral RNA. Results showed the type 1 poliovirus isolate, 5061, to be a novel wild-type poliovirus. The type 2 isolate, 5068, was closely related to the poliovirus type 2 Sabin vaccine strain, P712. It was concluded that the intrinsic variability of poliovirus strains was responsible for the appearance of isolate 5068
- Full Text:
- Date Issued: 1989
The life and times of Kama Chungwa, 1798-1875
- Authors: Yekela, Drusilla Siziwe
- Date: 1989
- Subjects: Kama, William, 1798-1875 , Shaw, William, 1798-1872 , Methodist Church of Southern Africa -- Missions , Gqunukhwebe (African people) -- History , Wesleyville mission , Gqunukhwebe (African people) -- Kings and rulers , South Africa -- History -- Frontier Wars, 1811-1878 , South Africa -- History -- Xhosa Cattle-Killing, 1856-1857 , Converts -- South Africa , Cape of Good Hope (South Africa) -- Politics and government
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2520 , http://hdl.handle.net/10962/d1001849
- Description: Few students of History understand the derivation and/or origin of the Gqunukhwebe oath "Ndifung' uChungw' efel' ennyameni: I swear by Chungwa who is lying dead at Mnyameni (Alexandria)." A desire to eludicate this point and other related facts inspired me to undertake a close examination of the history of the Gqunukhwebe people, selecting as my main theme the life-work of Chief Kama. In the first chapter I am discussing the creation of the Gqunukhwebe Chiefdom under Khwane by the Xhosa King, Tshiwo. The central theme here is the Black-White confrontation of the 17th - 18th centuries on the Cape Eastern Frontier. As a result of the collision the Gqunukhwebe people were forced to make a home on the banks of the Thwecu River along the east coast. It was here that Kama reached early manhood. The second chapter describes the establishment of Wesleyville Missionary Station by William Shaw in 1823, the first Methodist Missionary Institution in all Xhosaland. In chapter three the discussion centers on the significance of Kama's conversion. An unforeseen outcome of his public profession of the Christian faith was that it not only stigmatized the latter religion as a force destructive of the old order in Xhosa society, but it also reshaped Kama's political image for the good of his religious life. He not only fled from the neighbourhood of his relations and sojourned in a strange land, but also reinforced the Colonial forces in the contemporary frontier struggles. His integrity, self-sacrifice and pro-Colonial inclination eventually won him Middledrift. Chapter four opens with Kama's settling in Middledrift. The theme here is two-pronged. It presents the 'Cattle-Killing' delusion as a source of new trials for the 'priest-chief', and at the same time exposes the Colonial Government's efforts to gain ascendancy above the Xhosa chiefs. Kama's land was the first testing ground in this respect, and the Chief was initially agreeable to the scheme. Chapter five alludes to instances of Chief Kama's unco-operative attitude as signs that his compromising spirit had its limits. An atmosphere of disregard towards Kama pervades the period. But the adversities that threatened to dominate his later life did not by any means shake his Christian principles and convictions. The traces of his good works may to this day be seen in Middledrift, the traditional home of the Kamas.
- Full Text:
- Date Issued: 1989
- Authors: Yekela, Drusilla Siziwe
- Date: 1989
- Subjects: Kama, William, 1798-1875 , Shaw, William, 1798-1872 , Methodist Church of Southern Africa -- Missions , Gqunukhwebe (African people) -- History , Wesleyville mission , Gqunukhwebe (African people) -- Kings and rulers , South Africa -- History -- Frontier Wars, 1811-1878 , South Africa -- History -- Xhosa Cattle-Killing, 1856-1857 , Converts -- South Africa , Cape of Good Hope (South Africa) -- Politics and government
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:2520 , http://hdl.handle.net/10962/d1001849
- Description: Few students of History understand the derivation and/or origin of the Gqunukhwebe oath "Ndifung' uChungw' efel' ennyameni: I swear by Chungwa who is lying dead at Mnyameni (Alexandria)." A desire to eludicate this point and other related facts inspired me to undertake a close examination of the history of the Gqunukhwebe people, selecting as my main theme the life-work of Chief Kama. In the first chapter I am discussing the creation of the Gqunukhwebe Chiefdom under Khwane by the Xhosa King, Tshiwo. The central theme here is the Black-White confrontation of the 17th - 18th centuries on the Cape Eastern Frontier. As a result of the collision the Gqunukhwebe people were forced to make a home on the banks of the Thwecu River along the east coast. It was here that Kama reached early manhood. The second chapter describes the establishment of Wesleyville Missionary Station by William Shaw in 1823, the first Methodist Missionary Institution in all Xhosaland. In chapter three the discussion centers on the significance of Kama's conversion. An unforeseen outcome of his public profession of the Christian faith was that it not only stigmatized the latter religion as a force destructive of the old order in Xhosa society, but it also reshaped Kama's political image for the good of his religious life. He not only fled from the neighbourhood of his relations and sojourned in a strange land, but also reinforced the Colonial forces in the contemporary frontier struggles. His integrity, self-sacrifice and pro-Colonial inclination eventually won him Middledrift. Chapter four opens with Kama's settling in Middledrift. The theme here is two-pronged. It presents the 'Cattle-Killing' delusion as a source of new trials for the 'priest-chief', and at the same time exposes the Colonial Government's efforts to gain ascendancy above the Xhosa chiefs. Kama's land was the first testing ground in this respect, and the Chief was initially agreeable to the scheme. Chapter five alludes to instances of Chief Kama's unco-operative attitude as signs that his compromising spirit had its limits. An atmosphere of disregard towards Kama pervades the period. But the adversities that threatened to dominate his later life did not by any means shake his Christian principles and convictions. The traces of his good works may to this day be seen in Middledrift, the traditional home of the Kamas.
- Full Text:
- Date Issued: 1989
The Aapiesboomen magnesite deposit, Burgersfort, Transvaal
- Authors: Taylor, N C
- Date: 1974
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21130 , http://hdl.handle.net/10962/6505
- Description: The published literature on magnesite is extensively reviewed as regards the properties, uses, production, occurrence and genesis of the mineral. Despite opposition from the producers of sea water magnesia in recent years, magnesite still finds a ready market for the manufacture of refractory materials, particularly in the steel industry. Less important uses include the manufacture of magnesium metal, carbonic acid gas, Sorel cement, paper, pharmaceuticals and fertilizers. Large bodies of cryptocrystalline magnesite occur in Greece, Yugoslavia, Turkey and India, while the deposits in Austria, Czechoslovakia, Russia and China produce most of the world supply of crystalline material. Four types of magnesite bodies may be distinguished: quartz-magnesite deposits, talc-magnesite occurrences, magnesite associated with sedimentary rocks and sagvandite, a magnesite-bronzite rock. Most South African deposits, including the Aapiesboomen body, belong to the first type. Experimental, field and textural evidence indicates that the quartz-magnesite deposits may form from serpentine under a wide range of hydrothermal and supergene conditions below about 400°C and between very low and very high concentrations of co2 in the fluid phase. Above 400°C talc is produced at the expense of quartz. Sedimentary magnesite has been observed t o form in present day saline lakes, but the large size of the older crystalline deposits associated with limestones and dolomites has been used as an argument against the use of the same principle to explain the genesis of the latter bodies : much controversy still surrounds the sedimentary-hydrothermal debate concerning their origin. It seems probable thet sagvandites are produced by a process of CO2- metasomatism.
- Full Text:
- Date Issued: 1974
- Authors: Taylor, N C
- Date: 1974
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21130 , http://hdl.handle.net/10962/6505
- Description: The published literature on magnesite is extensively reviewed as regards the properties, uses, production, occurrence and genesis of the mineral. Despite opposition from the producers of sea water magnesia in recent years, magnesite still finds a ready market for the manufacture of refractory materials, particularly in the steel industry. Less important uses include the manufacture of magnesium metal, carbonic acid gas, Sorel cement, paper, pharmaceuticals and fertilizers. Large bodies of cryptocrystalline magnesite occur in Greece, Yugoslavia, Turkey and India, while the deposits in Austria, Czechoslovakia, Russia and China produce most of the world supply of crystalline material. Four types of magnesite bodies may be distinguished: quartz-magnesite deposits, talc-magnesite occurrences, magnesite associated with sedimentary rocks and sagvandite, a magnesite-bronzite rock. Most South African deposits, including the Aapiesboomen body, belong to the first type. Experimental, field and textural evidence indicates that the quartz-magnesite deposits may form from serpentine under a wide range of hydrothermal and supergene conditions below about 400°C and between very low and very high concentrations of co2 in the fluid phase. Above 400°C talc is produced at the expense of quartz. Sedimentary magnesite has been observed t o form in present day saline lakes, but the large size of the older crystalline deposits associated with limestones and dolomites has been used as an argument against the use of the same principle to explain the genesis of the latter bodies : much controversy still surrounds the sedimentary-hydrothermal debate concerning their origin. It seems probable thet sagvandites are produced by a process of CO2- metasomatism.
- Full Text:
- Date Issued: 1974
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