Evaluating farmers' perceptions on climate variability and the impact of management practices on rangeland condition at Tukulu Farm, South Africa
- Authors: Huza, Siphamandla
- Date: 2018
- Subjects: Rangelands -- South Africa -- Eastern Cape Range management -- South Africa -- Eastern Cape Livestock -- Breeding -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , Pasture Science
- Identifier: http://hdl.handle.net/10353/10586 , vital:35611
- Description: Rangelands are ecological systems largely used for extensive livestock production, which continually play a vital role in developing the economy of rural communities worldwide. These ecosystems also have the potential to provide vital secondary resources like medicinal plants, firewood and wild foods. This study assessed the impacts of management practices on rangeland condition at Tukulu communal farm in the Eastern Cape province of South Africa. Communal farmers’ perceptions were also investigated on vegetation change and awareness to climate variability. A structured questionnaire with open-ended and closed questions was used to interview communal farmers about several components of their rangeland, their awareness to climate variability and their household demographics were recorded. A rangeland condition assessment with the use of a three-tier system was used to determine vegetation condition and assessment of vegetal change over the past ten to twenty years. Botanical species composition, biomass yield, basal cover, woody plant density, browsing units and soil chemical composition were measured. Tukulu communal rangeland was demarcated into three homogenous vegetation units (HVU) namely, open grassland, scattered bushland and dense bushland. Sample sites of (100×50 m)2 with four replicates were constructed in each HVU. Herbaceous vegetation and basal cover were determined along 100 m transects in each sample site using a step-point method. Aboveground biomass production was estimated using a quadrat system following a systematic sampling by cutting all material within 0.25 m2 quadrats located along 100 m transects. Woody plant density (plants/ha), tree equivalents (TE/ha) and browsing unit (BU/ha) were estimated from the number of woody plants, total woody heights and the number of acceptable and available (<1.5 m) woody species. Soil sample analysis was conducted to determine OC, P, K, N, Ca, Mg, Na, Zn, Cu, and Mn and soil pH in all three HVUs. The respondents consisted of 65 percent males and 35 percent females with an average of about five persons per household. The study revealed that communal farmers at Tukulu were fairly knowledgeable about the changes that have occurred in their rangeland. All respondents 100 percent perceived that their rangeland had changed from good to poor condition. This was characterized by the shift from grass dominance to woody plant encroachment. These changes were linked to the perceived changes in climate. Farmers at Tukulu communal area were generally aware of the changes in climate, 95 percent of the respondents’ perceived changes in weather patterns such as changes in rain seasons, hot weather conditions, unpredictable rainfalls, drought, heavy winds and increased temperatures. The results revealed that Tukulu communal rangeland comprised of high species diversity. Twenty-one herbaceous species and 24 woody species were recorded at Tukulu rangeland. The grass species composition was characterised by 71 percent Increaser II species, 24 percent Decreaser and 5 percent Increaser I species. A highly palatable Decreaser species Themeda triandra decreased in abundance from open grassland to scattered bushland. There were no significant differences (p>0.05) in biomass yield in all three HVUs. However, scattered bushland 761.5 kg/ha and dense bushland 735.8 kg/ha had higher biomass yield when compared to open grassland 688.5 kg/ha. Bush encroachment was observed in dense bushland as the woody plant density 4487.5 trees/ha and tree equivalents 3451.3 trees/ha were significantly (P<0.05) higher than the recommended threshold standards of 2400 trees/ha and 2500 TE/ha. Scattered bushland had tree density of 1900 trees/ha and tree-equivalents of 1534.3 TE/ha. Soil macro and micro nutrients differed significantly between the different HVUs. The levels of Na, Ca, Mg, Cu, Mn differed significantly (p<0.05) between HVUs, increasing from open grassland to dense bushland. Organic carbon concentrations were higher under tree canopies in dense bushland. However, the levels of phosphorus and potassium were higher in open grassland than in the wooded areas. Soil pH in scattered bushland (5.3) and dense bushland (5.18) were significantly higher (p<0.05) than in open grassland (4.89). This study shows complications in management policies governing the Tukulu communal area. There is a need to merge both scientific and indigenous ecological knowledge to ensure the desired outcomes, as this could indeed offer some great insights for communal areas. Therefore, a rangeland rehabilitation programme should be implemented at Tukulu communal rangeland, which will address the issue of bush encroachment and implement a rotational grazing system by fencing camps that will be based on acceptable stocking rates.
- Full Text:
- Date Issued: 2018
- Authors: Huza, Siphamandla
- Date: 2018
- Subjects: Rangelands -- South Africa -- Eastern Cape Range management -- South Africa -- Eastern Cape Livestock -- Breeding -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , Pasture Science
- Identifier: http://hdl.handle.net/10353/10586 , vital:35611
- Description: Rangelands are ecological systems largely used for extensive livestock production, which continually play a vital role in developing the economy of rural communities worldwide. These ecosystems also have the potential to provide vital secondary resources like medicinal plants, firewood and wild foods. This study assessed the impacts of management practices on rangeland condition at Tukulu communal farm in the Eastern Cape province of South Africa. Communal farmers’ perceptions were also investigated on vegetation change and awareness to climate variability. A structured questionnaire with open-ended and closed questions was used to interview communal farmers about several components of their rangeland, their awareness to climate variability and their household demographics were recorded. A rangeland condition assessment with the use of a three-tier system was used to determine vegetation condition and assessment of vegetal change over the past ten to twenty years. Botanical species composition, biomass yield, basal cover, woody plant density, browsing units and soil chemical composition were measured. Tukulu communal rangeland was demarcated into three homogenous vegetation units (HVU) namely, open grassland, scattered bushland and dense bushland. Sample sites of (100×50 m)2 with four replicates were constructed in each HVU. Herbaceous vegetation and basal cover were determined along 100 m transects in each sample site using a step-point method. Aboveground biomass production was estimated using a quadrat system following a systematic sampling by cutting all material within 0.25 m2 quadrats located along 100 m transects. Woody plant density (plants/ha), tree equivalents (TE/ha) and browsing unit (BU/ha) were estimated from the number of woody plants, total woody heights and the number of acceptable and available (<1.5 m) woody species. Soil sample analysis was conducted to determine OC, P, K, N, Ca, Mg, Na, Zn, Cu, and Mn and soil pH in all three HVUs. The respondents consisted of 65 percent males and 35 percent females with an average of about five persons per household. The study revealed that communal farmers at Tukulu were fairly knowledgeable about the changes that have occurred in their rangeland. All respondents 100 percent perceived that their rangeland had changed from good to poor condition. This was characterized by the shift from grass dominance to woody plant encroachment. These changes were linked to the perceived changes in climate. Farmers at Tukulu communal area were generally aware of the changes in climate, 95 percent of the respondents’ perceived changes in weather patterns such as changes in rain seasons, hot weather conditions, unpredictable rainfalls, drought, heavy winds and increased temperatures. The results revealed that Tukulu communal rangeland comprised of high species diversity. Twenty-one herbaceous species and 24 woody species were recorded at Tukulu rangeland. The grass species composition was characterised by 71 percent Increaser II species, 24 percent Decreaser and 5 percent Increaser I species. A highly palatable Decreaser species Themeda triandra decreased in abundance from open grassland to scattered bushland. There were no significant differences (p>0.05) in biomass yield in all three HVUs. However, scattered bushland 761.5 kg/ha and dense bushland 735.8 kg/ha had higher biomass yield when compared to open grassland 688.5 kg/ha. Bush encroachment was observed in dense bushland as the woody plant density 4487.5 trees/ha and tree equivalents 3451.3 trees/ha were significantly (P<0.05) higher than the recommended threshold standards of 2400 trees/ha and 2500 TE/ha. Scattered bushland had tree density of 1900 trees/ha and tree-equivalents of 1534.3 TE/ha. Soil macro and micro nutrients differed significantly between the different HVUs. The levels of Na, Ca, Mg, Cu, Mn differed significantly (p<0.05) between HVUs, increasing from open grassland to dense bushland. Organic carbon concentrations were higher under tree canopies in dense bushland. However, the levels of phosphorus and potassium were higher in open grassland than in the wooded areas. Soil pH in scattered bushland (5.3) and dense bushland (5.18) were significantly higher (p<0.05) than in open grassland (4.89). This study shows complications in management policies governing the Tukulu communal area. There is a need to merge both scientific and indigenous ecological knowledge to ensure the desired outcomes, as this could indeed offer some great insights for communal areas. Therefore, a rangeland rehabilitation programme should be implemented at Tukulu communal rangeland, which will address the issue of bush encroachment and implement a rotational grazing system by fencing camps that will be based on acceptable stocking rates.
- Full Text:
- Date Issued: 2018
Competition factors influencing client switching behaviour within the commercial banking industry
- Authors: Mathiyase, Kholiswa
- Date: 2017
- Subjects: Banks and banking -- South Africa , Competition -- South Africa , Financial services industry -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/45366 , vital:38574
- Description: Banks are faced with challenges of retaining clients and preventing them from switching to competitors. For many years the South African banking industry has been dominated by the big four banks that were not known to be client focused. The banks were also known for serving only the middle and high-income earners, with the banks having a high and non-transparent banking fee structure. As a result, Capitec Bank was established in 2001 and differentiated itself from the traditional ways of providing banking service. One of their value propositions, Capitec Bank provided low and transparent banking fees, provided a unique personalised service to cater for the unbanked market and is gradually serving the middle and high-income market as well. Capitec Bank managed to establish its presence in the South African banking industry despite the dominance of the big four banks. The banking industry environment has also been subjected to a number of changes, including the entrants of other non-traditional banks, changing client behaviour, technology, regulatory and political reforms and the current depressed economic conditions.
- Full Text:
- Date Issued: 2017
- Authors: Mathiyase, Kholiswa
- Date: 2017
- Subjects: Banks and banking -- South Africa , Competition -- South Africa , Financial services industry -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10948/45366 , vital:38574
- Description: Banks are faced with challenges of retaining clients and preventing them from switching to competitors. For many years the South African banking industry has been dominated by the big four banks that were not known to be client focused. The banks were also known for serving only the middle and high-income earners, with the banks having a high and non-transparent banking fee structure. As a result, Capitec Bank was established in 2001 and differentiated itself from the traditional ways of providing banking service. One of their value propositions, Capitec Bank provided low and transparent banking fees, provided a unique personalised service to cater for the unbanked market and is gradually serving the middle and high-income market as well. Capitec Bank managed to establish its presence in the South African banking industry despite the dominance of the big four banks. The banking industry environment has also been subjected to a number of changes, including the entrants of other non-traditional banks, changing client behaviour, technology, regulatory and political reforms and the current depressed economic conditions.
- Full Text:
- Date Issued: 2017
An analysis of balanced scorecard for improved customer satisfaction in local government: a comparative study of the City of Cape Town and the City of Johannesburg
- Authors: Makina, Clive
- Date: 2016
- Subjects: Organizational effectiveness Consumer satisfaction Performance -- Management
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/4596 , vital:28463
- Description: This study sought to understand the application of the BSC as a tool that facilitates customer satisfaction in local government service delivery. The main thrust was on its application in South African metropolitan municipalities with a view of establishing means of improving its adoption for better customer-focused performance measurement. This area has not received much attention, yet local government performance is in an unacceptable state. The study employed a secondary data analysis approach and findings from the study reflect widespread usage of the BSC but without proper consideration of factors influencing its successful application. Findings of this study reinforce previous study results that there is poor communication with regards to how the BSC must be applied. Its application is also faced with the challenge of lack of training on the use and application of the BSC. However, the tool has significantly transformed and shaped the functioning of South Africa’s two best performing metropolitan municipalities and altered their performance in a favourable manner. Through the BSC approach, the City of Cape Town and the City of Johannesburg have moved towards improving their relations with the customers they serve. The BSC allows the municipalities to take into consideration the non-financial assets that were previously not considered valuable in organisations. Accommodating the views of customers has gained much traction in these municipalities and measures have been put in place to ensure real time data enables managers to make decisions that attempt to address people’s needs and expectations. Conclusively, the study recommends strong improvement in training and communication of the objectives and goals of a PMS within an organisation. Strong emphasis should also be placed on listening to what the customers say and expect from service delivery. This will strengthen the use and value of CSS and CBP and help improve performance and the achievement of the NDP goals of 2030 through local government. This study sought to understand the application of the BSC as a tool that facilitates customer satisfaction in local government service delivery. The main thrust was on its application in South African metropolitan municipalities with a view of establishing means of improving its adoption for better customer-focused performance measurement. This area has not received much attention, yet local government performance is in an unacceptable state. The study employed a secondary data analysis approach and findings from the study reflect widespread usage of the BSC but without proper consideration of factors influencing its successful application. Findings of this study reinforce previous study results that there is poor communication with regards to how the BSC must be applied. Its application is also faced with the challenge of lack of training on the use and application of the BSC. However, the tool has significantly transformed and shaped the functioning of South Africa’s two best performing metropolitan municipalities and altered their performance in a favourable manner. Through the BSC approach, the City of Cape Town and the City of Johannesburg have moved towards improving their relations with the customers they serve. The BSC allows the municipalities to take into consideration the non-financial assets that were previously not considered valuable in organisations. Accommodating the views of customers has gained much traction in these municipalities and measures have been put in place to ensure real time data enables managers to make decisions that attempt to address people’s needs and expectations. Conclusively, the study recommends strong improvement in training and communication of the objectives and goals of a PMS within an organisation. Strong emphasis should also be placed on listening to what the customers say and expect from service delivery. This will strengthen the use and value of CSS and CBP and help improve performance and the achievement of the NDP goals of 2030 through local government..
- Full Text:
- Date Issued: 2016
- Authors: Makina, Clive
- Date: 2016
- Subjects: Organizational effectiveness Consumer satisfaction Performance -- Management
- Language: English
- Type: Thesis , Masters , Degree
- Identifier: http://hdl.handle.net/10353/4596 , vital:28463
- Description: This study sought to understand the application of the BSC as a tool that facilitates customer satisfaction in local government service delivery. The main thrust was on its application in South African metropolitan municipalities with a view of establishing means of improving its adoption for better customer-focused performance measurement. This area has not received much attention, yet local government performance is in an unacceptable state. The study employed a secondary data analysis approach and findings from the study reflect widespread usage of the BSC but without proper consideration of factors influencing its successful application. Findings of this study reinforce previous study results that there is poor communication with regards to how the BSC must be applied. Its application is also faced with the challenge of lack of training on the use and application of the BSC. However, the tool has significantly transformed and shaped the functioning of South Africa’s two best performing metropolitan municipalities and altered their performance in a favourable manner. Through the BSC approach, the City of Cape Town and the City of Johannesburg have moved towards improving their relations with the customers they serve. The BSC allows the municipalities to take into consideration the non-financial assets that were previously not considered valuable in organisations. Accommodating the views of customers has gained much traction in these municipalities and measures have been put in place to ensure real time data enables managers to make decisions that attempt to address people’s needs and expectations. Conclusively, the study recommends strong improvement in training and communication of the objectives and goals of a PMS within an organisation. Strong emphasis should also be placed on listening to what the customers say and expect from service delivery. This will strengthen the use and value of CSS and CBP and help improve performance and the achievement of the NDP goals of 2030 through local government. This study sought to understand the application of the BSC as a tool that facilitates customer satisfaction in local government service delivery. The main thrust was on its application in South African metropolitan municipalities with a view of establishing means of improving its adoption for better customer-focused performance measurement. This area has not received much attention, yet local government performance is in an unacceptable state. The study employed a secondary data analysis approach and findings from the study reflect widespread usage of the BSC but without proper consideration of factors influencing its successful application. Findings of this study reinforce previous study results that there is poor communication with regards to how the BSC must be applied. Its application is also faced with the challenge of lack of training on the use and application of the BSC. However, the tool has significantly transformed and shaped the functioning of South Africa’s two best performing metropolitan municipalities and altered their performance in a favourable manner. Through the BSC approach, the City of Cape Town and the City of Johannesburg have moved towards improving their relations with the customers they serve. The BSC allows the municipalities to take into consideration the non-financial assets that were previously not considered valuable in organisations. Accommodating the views of customers has gained much traction in these municipalities and measures have been put in place to ensure real time data enables managers to make decisions that attempt to address people’s needs and expectations. Conclusively, the study recommends strong improvement in training and communication of the objectives and goals of a PMS within an organisation. Strong emphasis should also be placed on listening to what the customers say and expect from service delivery. This will strengthen the use and value of CSS and CBP and help improve performance and the achievement of the NDP goals of 2030 through local government..
- Full Text:
- Date Issued: 2016
An insight into the profile characteristics and technical batting skill of adolescent cricket players
- Authors: Clark, Matthew Edward
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2838 , vital:20331
- Description: Background: Current traditional cricket practices incorporate the use of a netted-off pitch to provide cricket players the opportunity to hone their skills with bat and ball. The lack of ecological validity of these training environments results in the absence of important task and environmental constraints which influences the manner in which the sport is played. Objectives: The purpose of the current research was two-fold: firstly, it aimed to establish a profile database of adolescent cricket players in the Eastern Cape province of South Africa; and secondly, it aimed to investigate the efficacy of a constraints-led training intervention on skill development in adolescent cricket batsmen. Methods: Study I required 90 participants (u13: n = 40; u15: n = 50) to perform measures pertaining to anthropometric, morphological, flexibility and physical performance characteristics. This included stature, mass, body composition, limb length, flexibility, agility, and power measures. Study II was a case-control study (u15: n = 24), whereby the experimental group (n = 12) was exposed to a constraints-led batting protocol during the course of the cricket season. The objective of the protocol was to encourage the manipulation of the ball around the playing field. Pre- and post-intervention measures were performed using a batting skills test, which assessed batsmen’s capability to manipulate the ball to various areas of the playing field. Results: Study I revealed significant differences (p <0.0001) in stature, mass, limb length and power variables when comparing the u15 age group with the u13 age group. No differences were recorded for agility. The u13 age group had greater linear correlations for the variables of interest compared to the u15 age group. Study II revealed no differences in technical skill between the experimental group and the control (p <0.315).. The tests also revealed that adolescent batsmen favoured hitting deliveries through the extra-cover scoring zone. The third-man and fine-leg scoring zones were least preferred to hit deliveries through. A number of limitations to the study design resulted in the inability to determine the efficacy of a constraints-led batting protocol on skill development in an adolescent batting cohort. Conclusion: The results of study I indicated that the onset of puberty played an important role in the measures and performances between the u13 and u15 age groups. The results of study II indicated that adolescent batsmen are not adept at manipulating the ball around the field. Recommendations are provided for both studies.
- Full Text:
- Date Issued: 2016
- Authors: Clark, Matthew Edward
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2838 , vital:20331
- Description: Background: Current traditional cricket practices incorporate the use of a netted-off pitch to provide cricket players the opportunity to hone their skills with bat and ball. The lack of ecological validity of these training environments results in the absence of important task and environmental constraints which influences the manner in which the sport is played. Objectives: The purpose of the current research was two-fold: firstly, it aimed to establish a profile database of adolescent cricket players in the Eastern Cape province of South Africa; and secondly, it aimed to investigate the efficacy of a constraints-led training intervention on skill development in adolescent cricket batsmen. Methods: Study I required 90 participants (u13: n = 40; u15: n = 50) to perform measures pertaining to anthropometric, morphological, flexibility and physical performance characteristics. This included stature, mass, body composition, limb length, flexibility, agility, and power measures. Study II was a case-control study (u15: n = 24), whereby the experimental group (n = 12) was exposed to a constraints-led batting protocol during the course of the cricket season. The objective of the protocol was to encourage the manipulation of the ball around the playing field. Pre- and post-intervention measures were performed using a batting skills test, which assessed batsmen’s capability to manipulate the ball to various areas of the playing field. Results: Study I revealed significant differences (p <0.0001) in stature, mass, limb length and power variables when comparing the u15 age group with the u13 age group. No differences were recorded for agility. The u13 age group had greater linear correlations for the variables of interest compared to the u15 age group. Study II revealed no differences in technical skill between the experimental group and the control (p <0.315).. The tests also revealed that adolescent batsmen favoured hitting deliveries through the extra-cover scoring zone. The third-man and fine-leg scoring zones were least preferred to hit deliveries through. A number of limitations to the study design resulted in the inability to determine the efficacy of a constraints-led batting protocol on skill development in an adolescent batting cohort. Conclusion: The results of study I indicated that the onset of puberty played an important role in the measures and performances between the u13 and u15 age groups. The results of study II indicated that adolescent batsmen are not adept at manipulating the ball around the field. Recommendations are provided for both studies.
- Full Text:
- Date Issued: 2016
The associative behaviour of silky sharks, Carcharhinus falciformis, with floating objects in the open ocean
- Authors: Filmalter, John David
- Date: 2015
- Subjects: Silky shark , Silky shark -- Behavior , Silky shark -- Marking , Silky shark -- Food , Tuna fisheries -- Bycatches , Fish aggregation devices , Underwater acoustic telemetry , Fish tagging
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5381 , http://hdl.handle.net/10962/d1018177
- Description: The silky shark Carcharhinus falciformis forms the primary elasmobranch bycatch in tuna purse seine fisheries using fish aggregating devices (FADs) in all of the world’s tropical oceans. Its life-history traits of slow growth, late maturation and low fecundity make it vulnerable to over exploitation, as is apparent from historical bycatch trends. Very little is known about the associative behaviour of this species with floating objects, information which is essential in formulating effective mitigation and management measures. This study aims to address this knowledge gap through the use of various electronic tagging techniques in conjunction with dietary analysis. Dietary data were collected from 323 silky sharks incidentally caught at FADs. Approximately 40 percent of the diet consisted of prey associated with FADs while the remaining 60 percent were non-associated species of crustaceans, cephalopods and fishes. These results suggest that the associative behaviour is not primarily driven by trophic enhancement, but is likely a combination of predator avoidance, social interactions and feeding. Fine-scale behavioural data from silky sharks associated with drifting FADs were collected through the use of acoustic telemetry techniques. Acoustic tags were implanted into 38 silky sharks (69- 116 cm TL) at eight FADs. FADs were equipped with satellite linked acoustic receivers and abandoned to drift freely. Presence/absence and swimming depth data were telemetered via the Iridium satellite system. A total of 300 d of behavioural data were collected from 20 tagged individuals. Individuals remain associated with the same FAD for extended periods (min = 2.84 d, max = 30.60 d, mean = 15.69 d). Strong diel patterns were observed in both association and swimming depth. Typically individuals moved away from FADs after sunset and return later during the night, then remain closely associated until the following evening. Vertical behaviour also changed around sunset with sharks using fairly constant depths, within the upper 25 m, during the day and switching to rapid vertical movements during the night, with dives in excess of 250 m recoded. Broader scale movement behaviour was investigated using pop-up archival satellite tags (PSATs). Tags were deployed on 46 silky sharks (86-224.5 cm TL) for a total of 1495 d. Light data were used to calculate geolocation estimates and reconstruct the sharks’ trajectories. Movement patterns differed between animals and according to deployment duration. Several extensive horizontal movements were observed, with an average track length of 3240 km during an average tag deployment of 44.02 d. Horizontal movement patterns were found to correlate very closely with drift patterns of FADs. Consequently, it appears that the movement behaviour of juvenile silky sharks is strongly influenced by the movement of drifting FADs in this region. Ghost fishing of silky sharks through entanglement in FADs was also investigated using data derived from PSATs as well as underwater visual censuses. Thirteen per cent of the tagged sharks became entangled in FADs and entangled sharks were observed in 35 percent of the 51 FADs surveyed. Using this information in conjunction with estimated time that sharks remained entangled in the FAD (from depth data from PSATs), and scaling up according to estimates of FAD numbers, it was found that between 480 000 and 960 000 silky sharks are killed annually in this manner in the Indian Ocean. Subsequent management measures in this region prevent the deployment of FADs with netting that could lead to entanglement. Overall, floating objects appear to play a significant role in the juvenile life stages of silky sharks in this region. While their association with floating objects is clearly advantageous in an evolutionary sense, under current tuna fishery trends, this behaviour is certainly detrimental for the population.
- Full Text:
- Date Issued: 2015
- Authors: Filmalter, John David
- Date: 2015
- Subjects: Silky shark , Silky shark -- Behavior , Silky shark -- Marking , Silky shark -- Food , Tuna fisheries -- Bycatches , Fish aggregation devices , Underwater acoustic telemetry , Fish tagging
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5381 , http://hdl.handle.net/10962/d1018177
- Description: The silky shark Carcharhinus falciformis forms the primary elasmobranch bycatch in tuna purse seine fisheries using fish aggregating devices (FADs) in all of the world’s tropical oceans. Its life-history traits of slow growth, late maturation and low fecundity make it vulnerable to over exploitation, as is apparent from historical bycatch trends. Very little is known about the associative behaviour of this species with floating objects, information which is essential in formulating effective mitigation and management measures. This study aims to address this knowledge gap through the use of various electronic tagging techniques in conjunction with dietary analysis. Dietary data were collected from 323 silky sharks incidentally caught at FADs. Approximately 40 percent of the diet consisted of prey associated with FADs while the remaining 60 percent were non-associated species of crustaceans, cephalopods and fishes. These results suggest that the associative behaviour is not primarily driven by trophic enhancement, but is likely a combination of predator avoidance, social interactions and feeding. Fine-scale behavioural data from silky sharks associated with drifting FADs were collected through the use of acoustic telemetry techniques. Acoustic tags were implanted into 38 silky sharks (69- 116 cm TL) at eight FADs. FADs were equipped with satellite linked acoustic receivers and abandoned to drift freely. Presence/absence and swimming depth data were telemetered via the Iridium satellite system. A total of 300 d of behavioural data were collected from 20 tagged individuals. Individuals remain associated with the same FAD for extended periods (min = 2.84 d, max = 30.60 d, mean = 15.69 d). Strong diel patterns were observed in both association and swimming depth. Typically individuals moved away from FADs after sunset and return later during the night, then remain closely associated until the following evening. Vertical behaviour also changed around sunset with sharks using fairly constant depths, within the upper 25 m, during the day and switching to rapid vertical movements during the night, with dives in excess of 250 m recoded. Broader scale movement behaviour was investigated using pop-up archival satellite tags (PSATs). Tags were deployed on 46 silky sharks (86-224.5 cm TL) for a total of 1495 d. Light data were used to calculate geolocation estimates and reconstruct the sharks’ trajectories. Movement patterns differed between animals and according to deployment duration. Several extensive horizontal movements were observed, with an average track length of 3240 km during an average tag deployment of 44.02 d. Horizontal movement patterns were found to correlate very closely with drift patterns of FADs. Consequently, it appears that the movement behaviour of juvenile silky sharks is strongly influenced by the movement of drifting FADs in this region. Ghost fishing of silky sharks through entanglement in FADs was also investigated using data derived from PSATs as well as underwater visual censuses. Thirteen per cent of the tagged sharks became entangled in FADs and entangled sharks were observed in 35 percent of the 51 FADs surveyed. Using this information in conjunction with estimated time that sharks remained entangled in the FAD (from depth data from PSATs), and scaling up according to estimates of FAD numbers, it was found that between 480 000 and 960 000 silky sharks are killed annually in this manner in the Indian Ocean. Subsequent management measures in this region prevent the deployment of FADs with netting that could lead to entanglement. Overall, floating objects appear to play a significant role in the juvenile life stages of silky sharks in this region. While their association with floating objects is clearly advantageous in an evolutionary sense, under current tuna fishery trends, this behaviour is certainly detrimental for the population.
- Full Text:
- Date Issued: 2015
Alternative methods used by small-holder farmers to control ticks and bovine dermatophilosis and the impact of a changing interface of Amblyomma ticks on dermatophilosis in Zimbabwe
- Authors: Ndhkovu, Daud Nyosi
- Date: 2014
- Subjects: Ticks -- Control -- Africa, Southern , Dermatophilosis
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11830 , http://hdl.handle.net/10353/d1019764 , Ticks -- Control -- Africa, Southern , Dermatophilosis
- Description: This study was carried out to document the ethno-veterinary plants and non-plant remedies that farmers used to control dermatophilosis and ticks, and validate these in vitro and in vivo, as well as determine how the interface of Amblyomma variegatum and A. hebraeum affected the epidemiology of bovine dermatophilosis at selected small-holder areas in North-West Zimbabwe. A structured questionnaire survey was used to collect information on the control methods used by farmers for the control of bovine dermatophilosis and ticks. A total of 39 plants were used by farmers for various diseases, eleven of these plants were used for the control of dermatophilosis while three were for tick control. Across the study sites, dermatophilosis was controlled using eleven plants. Among these plants; six plants; Cissus quadrangularis, Catunaregan spinosa, Pterocarpus angolensis Carica papaya, Manihot esculenta and Blumea decurrens which were frequently used were selected for further studies. In vitro and in vivo studies were conducted to validate the efficacy of these plants. The minimum inhibitory concentration and bactericidal concentration assays were used for the in vitro validation of C. quadrangularis, C. spinosa and P. angolensis. Dermatophilus congolensis was more sensitive to P. angolensis average MIC = 0.63 mg/ml than to C. quadrangularis average MIC = iii 1.25 mg/ml and C. spinosa average MIC = 2.08 mg/ml. Cissus quadrangularis was selected for in vivo studies as this plant was the one most frequently used by farmers. Its therapeutic efficacy was compared to conventional antibiotics that farmers used to treat dermatophilosis infection. In the in vivo trials C. quadrangularis did not lead to appreciable reduction in clinical disease compared to the conventional drugs. The larval packet assay was the in vitro assay used to validate the efficacy of Carica papaya, Manihot esculenta and Blumea decurrens against larvae of A. hebraeum and Rhipicephalus appendiculatus. Manihot esculenta at 20 % w/v exhibited the highest larvicidal activity against R. appendiculatus. In the in vivo study, efficacy of the plants were investigated on naturally tick-infested cattle. Mannihot esculenta exhibited the largest tick load reduction compared to the other two plants but its performance was lower than that of conventional acaricides. The effect of A. variegatum and A. hebraeum on bovine dermatophilosis was investigated by evaluating how the presence or absence of these ticks and other herd level risk factors predicted clinical dermatophilosis and its prevalence at herd level. A structured questionnaire survey was carried out to collect data on potential risk factors. At the same time, cattle were physically examined for the presence of bovine dermatophilosis, according to a pre-defined case definition, and presence or absence of Amblyomma ticks was also recorded. The multivariable binary logistic model was developed with disease status as outcome, tick presence and infestion and herd level risk factors as predictors. Of the herds examined clinical bovine dermatophilosis was detected in 45% (84/185; 95% CI: 38.2, 52.6%) of them. Herds infested with Amblyomma variegatum were associated with higher odds (OR= 6.8; iv 95% CI: 1.71, 27.10) of clinical dermatophilosis while the association was not significant (P > 0.05) in A. hebraeum infested herds. It was concluded that management practices aimed at movement and tick control would help reduce the prevalence of clinical dermatophilosis in herds.
- Full Text:
- Date Issued: 2014
- Authors: Ndhkovu, Daud Nyosi
- Date: 2014
- Subjects: Ticks -- Control -- Africa, Southern , Dermatophilosis
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11830 , http://hdl.handle.net/10353/d1019764 , Ticks -- Control -- Africa, Southern , Dermatophilosis
- Description: This study was carried out to document the ethno-veterinary plants and non-plant remedies that farmers used to control dermatophilosis and ticks, and validate these in vitro and in vivo, as well as determine how the interface of Amblyomma variegatum and A. hebraeum affected the epidemiology of bovine dermatophilosis at selected small-holder areas in North-West Zimbabwe. A structured questionnaire survey was used to collect information on the control methods used by farmers for the control of bovine dermatophilosis and ticks. A total of 39 plants were used by farmers for various diseases, eleven of these plants were used for the control of dermatophilosis while three were for tick control. Across the study sites, dermatophilosis was controlled using eleven plants. Among these plants; six plants; Cissus quadrangularis, Catunaregan spinosa, Pterocarpus angolensis Carica papaya, Manihot esculenta and Blumea decurrens which were frequently used were selected for further studies. In vitro and in vivo studies were conducted to validate the efficacy of these plants. The minimum inhibitory concentration and bactericidal concentration assays were used for the in vitro validation of C. quadrangularis, C. spinosa and P. angolensis. Dermatophilus congolensis was more sensitive to P. angolensis average MIC = 0.63 mg/ml than to C. quadrangularis average MIC = iii 1.25 mg/ml and C. spinosa average MIC = 2.08 mg/ml. Cissus quadrangularis was selected for in vivo studies as this plant was the one most frequently used by farmers. Its therapeutic efficacy was compared to conventional antibiotics that farmers used to treat dermatophilosis infection. In the in vivo trials C. quadrangularis did not lead to appreciable reduction in clinical disease compared to the conventional drugs. The larval packet assay was the in vitro assay used to validate the efficacy of Carica papaya, Manihot esculenta and Blumea decurrens against larvae of A. hebraeum and Rhipicephalus appendiculatus. Manihot esculenta at 20 % w/v exhibited the highest larvicidal activity against R. appendiculatus. In the in vivo study, efficacy of the plants were investigated on naturally tick-infested cattle. Mannihot esculenta exhibited the largest tick load reduction compared to the other two plants but its performance was lower than that of conventional acaricides. The effect of A. variegatum and A. hebraeum on bovine dermatophilosis was investigated by evaluating how the presence or absence of these ticks and other herd level risk factors predicted clinical dermatophilosis and its prevalence at herd level. A structured questionnaire survey was carried out to collect data on potential risk factors. At the same time, cattle were physically examined for the presence of bovine dermatophilosis, according to a pre-defined case definition, and presence or absence of Amblyomma ticks was also recorded. The multivariable binary logistic model was developed with disease status as outcome, tick presence and infestion and herd level risk factors as predictors. Of the herds examined clinical bovine dermatophilosis was detected in 45% (84/185; 95% CI: 38.2, 52.6%) of them. Herds infested with Amblyomma variegatum were associated with higher odds (OR= 6.8; iv 95% CI: 1.71, 27.10) of clinical dermatophilosis while the association was not significant (P > 0.05) in A. hebraeum infested herds. It was concluded that management practices aimed at movement and tick control would help reduce the prevalence of clinical dermatophilosis in herds.
- Full Text:
- Date Issued: 2014
A Comparative study of two copper(II) based metal-organic frameworks : Cu2¼(OH)½B4C•8H2O and Cu2Na(OH)B4C•7H2O
- Authors: Coombes, Matthew
- Date: 2013
- Subjects: Copper , Organometallic compounds , Supramolecular organometallic chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4533 , http://hdl.handle.net/10962/d1016245
- Description: This study focussed on two copper(II)-containing metal-organic frameworks (MOFs): Cu2Na(OH)B4C•7H2O and Cu2¼(OH)½B4C•8H2O (B4C = 1,2,4,5- benzenetetracarboxylate). They are both covalent, three-dimensional metalorganic framework polymers containing voids filled with water molecules. Both were characterised by elemental analysis, infrared spectroscopy, X-ray powder diffractometry (both in situ and regular), thermogravimetric analysis, differential scanning calorimetry and X-ray photoelectron spectroscopy. These two MOFs are essentially identical, with the only difference being the substitution of sodium by copper at every 4th site (disordered throughout the crystal). The guest inclusion properties of both MOFs were studied and compared. Although both structures collapse on dehydration, it was observed that Cu2Na(OH)B4C•7H2O is able to take up signifcant amounts of water, methanol and ethanol. All these processes are fully reversible. Car-Parrinello molecular dynamics studies suggest that it is a strong interaction between the oxygen atoms on these molecules with the sodium cation of the MOF that is responsible for this signifcant uptake. In contrast, Cu2¼ (OH)½ B4C•8H2O, the MOF without a sodium cation, did not demonstrate any methanol or ethanol uptake, but was able to take up some water. The uptake of water, however, is not a fully reversible process. The absence of sodium likely results in insuffcient energy to draw methanol and ethanol into the framework, while a subtle rotation of a carboxylate group on dehydration decreases the ability of the framework to form hydrogen bonds, thus reducing the ability to take up water. A series of hydrothermal syntheses were performed in order to develop a method of synthesis superior to the current gel-based synthesis that requires several months and has poor yields. The hydrothermal products were characterized by elemental analysis, infrared spectroscopy, X-ray powder diffractometry, thermogravimetric analysis and differential scanning calorimetry. It was shown that the MOF Cu2Na(OH)B4C•7H2O may be synthesised in almost 100% yield by using a temperature of 120°C over a period of 72 hours. It was not possible to synthesise Cu2¼ (OH)½ B4C•8H2O in a 100% yield - it was only obtained as a minor product.
- Full Text:
- Date Issued: 2013
- Authors: Coombes, Matthew
- Date: 2013
- Subjects: Copper , Organometallic compounds , Supramolecular organometallic chemistry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4533 , http://hdl.handle.net/10962/d1016245
- Description: This study focussed on two copper(II)-containing metal-organic frameworks (MOFs): Cu2Na(OH)B4C•7H2O and Cu2¼(OH)½B4C•8H2O (B4C = 1,2,4,5- benzenetetracarboxylate). They are both covalent, three-dimensional metalorganic framework polymers containing voids filled with water molecules. Both were characterised by elemental analysis, infrared spectroscopy, X-ray powder diffractometry (both in situ and regular), thermogravimetric analysis, differential scanning calorimetry and X-ray photoelectron spectroscopy. These two MOFs are essentially identical, with the only difference being the substitution of sodium by copper at every 4th site (disordered throughout the crystal). The guest inclusion properties of both MOFs were studied and compared. Although both structures collapse on dehydration, it was observed that Cu2Na(OH)B4C•7H2O is able to take up signifcant amounts of water, methanol and ethanol. All these processes are fully reversible. Car-Parrinello molecular dynamics studies suggest that it is a strong interaction between the oxygen atoms on these molecules with the sodium cation of the MOF that is responsible for this signifcant uptake. In contrast, Cu2¼ (OH)½ B4C•8H2O, the MOF without a sodium cation, did not demonstrate any methanol or ethanol uptake, but was able to take up some water. The uptake of water, however, is not a fully reversible process. The absence of sodium likely results in insuffcient energy to draw methanol and ethanol into the framework, while a subtle rotation of a carboxylate group on dehydration decreases the ability of the framework to form hydrogen bonds, thus reducing the ability to take up water. A series of hydrothermal syntheses were performed in order to develop a method of synthesis superior to the current gel-based synthesis that requires several months and has poor yields. The hydrothermal products were characterized by elemental analysis, infrared spectroscopy, X-ray powder diffractometry, thermogravimetric analysis and differential scanning calorimetry. It was shown that the MOF Cu2Na(OH)B4C•7H2O may be synthesised in almost 100% yield by using a temperature of 120°C over a period of 72 hours. It was not possible to synthesise Cu2¼ (OH)½ B4C•8H2O in a 100% yield - it was only obtained as a minor product.
- Full Text:
- Date Issued: 2013
An exploratory case study of a Foundation Phase learning program to examine how curriculum contextualisation contributes to environmental learning and relevance
- Authors: Maqwelane, Nonkoliso Sheila
- Date: 2012
- Subjects: Education, Primary -- Research -- South Africa Environmental education -- Study and teaching (Elementary) -- South Africa Curriculum planning -- Research -- South Africa Literacy -- Study and teaching (Elementary) -- Research -- South Africa Life skills -- Study and teaching (Elementary) -- Research -- South Africa Experiential learning -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1889 , http://hdl.handle.net/10962/d1006041
- Description: This study is an exploration of contextual environmental learning through integrated life skills and literacy in a Foundation Phase classroom. It attempts to document, explore and clarify some of the challenges of situated environmental learning in a Foundation Phase classroom through an integrated program of life skills learning and literacy acquisition. The research draws on a rich but often overlooked cultural historical context of embodied intergenerational healthy living practices in a rural Eastern Cape context to construct a learning platform for a more carefully situated and potentially relevant education. The integrated life skills and literacy acquisition program thus unfolded as a contextual process of situated learning within a developing blend of listening, writing and reading to learn in a Grade 3 program of additive bilingualism. The data generated in the study and represented in Chapter 4 suggests curriculum contextualisation in an integrated Foundation Phase program can contribute to environmental learning with enhanced relevance and literacy skills. The evidence from working with learner knowledge and experience in a community context appears to be a key to meaningful curriculum contextualization in an integrated Foundation Phase programme producing enhanced literacy and relevance. It was noted that engaging elders (gogos) enabled the process of opening up local knowledge to link with learner experience and school knowledge to foster relevance, appeared to contribute to more meaningful learning across other learning areas. There is evidence that acquiring literacy skills is a lengthy process that is supported by learner interest and the relevance of what they are learning especially when it is acknowledged by the teacher and the community. The findings of an exploratory study such as this cannot be conclusive beyond the experience that I had of working with learners who were engaged in learning as well as acquiring literacy skills literacy skills. My personal enthusiasm and work with the Gogos and with a community focus were key factors that strengthened environmental learning across school, home and community. The experience has convinced me that this is the way we must work to enhance relevance and literacy in our Foundation Phase teaching.
- Full Text:
- Date Issued: 2012
- Authors: Maqwelane, Nonkoliso Sheila
- Date: 2012
- Subjects: Education, Primary -- Research -- South Africa Environmental education -- Study and teaching (Elementary) -- South Africa Curriculum planning -- Research -- South Africa Literacy -- Study and teaching (Elementary) -- Research -- South Africa Life skills -- Study and teaching (Elementary) -- Research -- South Africa Experiential learning -- Research -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1889 , http://hdl.handle.net/10962/d1006041
- Description: This study is an exploration of contextual environmental learning through integrated life skills and literacy in a Foundation Phase classroom. It attempts to document, explore and clarify some of the challenges of situated environmental learning in a Foundation Phase classroom through an integrated program of life skills learning and literacy acquisition. The research draws on a rich but often overlooked cultural historical context of embodied intergenerational healthy living practices in a rural Eastern Cape context to construct a learning platform for a more carefully situated and potentially relevant education. The integrated life skills and literacy acquisition program thus unfolded as a contextual process of situated learning within a developing blend of listening, writing and reading to learn in a Grade 3 program of additive bilingualism. The data generated in the study and represented in Chapter 4 suggests curriculum contextualisation in an integrated Foundation Phase program can contribute to environmental learning with enhanced relevance and literacy skills. The evidence from working with learner knowledge and experience in a community context appears to be a key to meaningful curriculum contextualization in an integrated Foundation Phase programme producing enhanced literacy and relevance. It was noted that engaging elders (gogos) enabled the process of opening up local knowledge to link with learner experience and school knowledge to foster relevance, appeared to contribute to more meaningful learning across other learning areas. There is evidence that acquiring literacy skills is a lengthy process that is supported by learner interest and the relevance of what they are learning especially when it is acknowledged by the teacher and the community. The findings of an exploratory study such as this cannot be conclusive beyond the experience that I had of working with learners who were engaged in learning as well as acquiring literacy skills literacy skills. My personal enthusiasm and work with the Gogos and with a community focus were key factors that strengthened environmental learning across school, home and community. The experience has convinced me that this is the way we must work to enhance relevance and literacy in our Foundation Phase teaching.
- Full Text:
- Date Issued: 2012
Implementation of environmental learning in the NSSC biology curriculum component: a case study of Namibia
- Tshiningayamwe, Sirkka Alina Nambashusan
- Authors: Tshiningayamwe, Sirkka Alina Nambashusan
- Date: 2012
- Subjects: Environmental education -- Namibia -- Case studies Environmental education -- Study and teaching (Secondary) -- Namibia -- Case studies Environmental education -- Evaluation -- Namibia -- Case studies Biology -- Study and teaching (Secondary) -- Namibia -- Case studies Biology -- Curricula
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1564 , http://hdl.handle.net/10962/d1003446
- Description: In the context of ecological crisis and environmental deterioration, teaching about environmental issues and the preservation of the world’s environment has become increasingly important across the globe (Chi-chung Ko & Chi-kin Lee, 2003). Of the various subjects taught in secondary schools, Science is often perceived as one that can make a significant contribution to environmental education. It is in this light that the study has looked at how Grade 11 and 12 Biology teachers in the Namibian context implement Environmental Learning (EL). This study was constituted as a case study of two schools in Windhoek, in the Khomas region. The study investigated the implementation of EL in the Biology curriculum focusing on the constraints and enabling factors influencing the implementation. This study employed qualitative methods, specifically semi-structured interviews, classroom observations and document analysis in its investigation of EL implementation. Purposive sampling was done and piloting of interview and observation schedules was used to refine the schedules. Ethical issues were taken into consideration throughout the study. The key findings from the study are as follows: - Teachers’ knowledge and interest in environmental education influence how teachers facilitate EL; - There is a mismatch between EL theories and practice; - Teaching of EL is mainly informed by the syllabus and not other curriculum documents, - Current assessment policy and practice impact on EL; and - Possibilities exist for improving EL in Namibia’s Biology curriculum. These key findings have been used to make recommendations for the study which are as follows: - Strengthen the subject content and interest of teachers; - There should be a match between EL theories and practice; - Reorient curriculum documents and other learning support materials used for EL; - Change in assessment approaches; and - Translate constraints of EL into enablers. The study concludes by calling for further research into EL pedagogies. This can be used to improve EL implementation in the region where the study was situated.
- Full Text:
- Date Issued: 2012
- Authors: Tshiningayamwe, Sirkka Alina Nambashusan
- Date: 2012
- Subjects: Environmental education -- Namibia -- Case studies Environmental education -- Study and teaching (Secondary) -- Namibia -- Case studies Environmental education -- Evaluation -- Namibia -- Case studies Biology -- Study and teaching (Secondary) -- Namibia -- Case studies Biology -- Curricula
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1564 , http://hdl.handle.net/10962/d1003446
- Description: In the context of ecological crisis and environmental deterioration, teaching about environmental issues and the preservation of the world’s environment has become increasingly important across the globe (Chi-chung Ko & Chi-kin Lee, 2003). Of the various subjects taught in secondary schools, Science is often perceived as one that can make a significant contribution to environmental education. It is in this light that the study has looked at how Grade 11 and 12 Biology teachers in the Namibian context implement Environmental Learning (EL). This study was constituted as a case study of two schools in Windhoek, in the Khomas region. The study investigated the implementation of EL in the Biology curriculum focusing on the constraints and enabling factors influencing the implementation. This study employed qualitative methods, specifically semi-structured interviews, classroom observations and document analysis in its investigation of EL implementation. Purposive sampling was done and piloting of interview and observation schedules was used to refine the schedules. Ethical issues were taken into consideration throughout the study. The key findings from the study are as follows: - Teachers’ knowledge and interest in environmental education influence how teachers facilitate EL; - There is a mismatch between EL theories and practice; - Teaching of EL is mainly informed by the syllabus and not other curriculum documents, - Current assessment policy and practice impact on EL; and - Possibilities exist for improving EL in Namibia’s Biology curriculum. These key findings have been used to make recommendations for the study which are as follows: - Strengthen the subject content and interest of teachers; - There should be a match between EL theories and practice; - Reorient curriculum documents and other learning support materials used for EL; - Change in assessment approaches; and - Translate constraints of EL into enablers. The study concludes by calling for further research into EL pedagogies. This can be used to improve EL implementation in the region where the study was situated.
- Full Text:
- Date Issued: 2012
An investigation of student leadership in an independent school in the Eastern Cape: ʺdo alternative forms of leadership (such as servant leadership) emerge through community building?ʺ
- Authors: Knott-Craig, Ian Duncan
- Date: 2008
- Subjects: Kingswood College Private schools -- South Africa -- Eastern Cape Servant leadership -- South Africa -- Eastern Cape Educational leadership -- South Africa -- Eastern Cape Community and school -- South Africa -- Eastern Cape Student volunteers in social service -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1643 , http://hdl.handle.net/10962/d1003525
- Description: Significant changes have taken place in recent years in leadership theory and practice world wide. Theorizations of effective leadership have evolved from being authoritarian and task-centered to a model in which leaders are encouraged to look beyond their self-interest and prioritize the interests of the group. This study investigates the development of an alternative form of leadership through community building in two male school boarding houses. It attempts to ascertain whether students are able to work collaboratively towards developing an environment conducive to servant leadership. Structured according to the transformative research paradigm, this action research study was conducted in an independent school, Kingswood College, in Grahamstown, South Africa. The College is a traditional independent co-educational school that prides itself on producing leaders. As the school was in the process of reviewing its leadership system, it became an appropriate site to investigate the development of community and to explore possibilities for the emergence of an alternative form of leadership that would reflect the attributes of servant leadership. The participants in the study were volunteers from two boarding houses, who agreed to reflect on their perceptions and experiences of the way in which their houses functioned. My research findings show that through their willingness to engage in moral dialogue, students can transform their boarding houses into closely-knit communities bound together by shared values and beliefs. Closer relationships make for better understanding. As the leaders take on the responsibility of caring for their juniors, a moral obligation begins to manifest itself. Leaders will display the attributes of servant leadership if they are prepared to acknowledge in practice this moral obligation to serve others.
- Full Text:
- Date Issued: 2008
- Authors: Knott-Craig, Ian Duncan
- Date: 2008
- Subjects: Kingswood College Private schools -- South Africa -- Eastern Cape Servant leadership -- South Africa -- Eastern Cape Educational leadership -- South Africa -- Eastern Cape Community and school -- South Africa -- Eastern Cape Student volunteers in social service -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1643 , http://hdl.handle.net/10962/d1003525
- Description: Significant changes have taken place in recent years in leadership theory and practice world wide. Theorizations of effective leadership have evolved from being authoritarian and task-centered to a model in which leaders are encouraged to look beyond their self-interest and prioritize the interests of the group. This study investigates the development of an alternative form of leadership through community building in two male school boarding houses. It attempts to ascertain whether students are able to work collaboratively towards developing an environment conducive to servant leadership. Structured according to the transformative research paradigm, this action research study was conducted in an independent school, Kingswood College, in Grahamstown, South Africa. The College is a traditional independent co-educational school that prides itself on producing leaders. As the school was in the process of reviewing its leadership system, it became an appropriate site to investigate the development of community and to explore possibilities for the emergence of an alternative form of leadership that would reflect the attributes of servant leadership. The participants in the study were volunteers from two boarding houses, who agreed to reflect on their perceptions and experiences of the way in which their houses functioned. My research findings show that through their willingness to engage in moral dialogue, students can transform their boarding houses into closely-knit communities bound together by shared values and beliefs. Closer relationships make for better understanding. As the leaders take on the responsibility of caring for their juniors, a moral obligation begins to manifest itself. Leaders will display the attributes of servant leadership if they are prepared to acknowledge in practice this moral obligation to serve others.
- Full Text:
- Date Issued: 2008
A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA
- Authors: Richter, Laura
- Date: 2006
- Subjects: Very long baseline interferometry , Polarization (Light) , Masers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5498 , http://hdl.handle.net/10962/d1005284
- Description: This thesis reports the calibration, imaging and analysis of one epoch of VLBI observations of the v (italics) = J (italics) = 1-0 transition of SiO towards VY CMa. Full polarisation information was recorded, allowing high resolution synthesis maps of each of the four Stokes parameters to be produced. A total of 81 maser components were extracted from the total intensity map, each approximately 1 mas in size. The emission spans approximately 100 x 80 mas in right ascension and declination and is concentrated to the east. The maser component positions were fitted to a ring of radius ~ 3.2R₊ (italics), or 7.2 x 1O¹⁴ cm for a stellar distance of 1.5 kpc. If the stellar position is assumed to be the centre of this ring then almost all of the maser components fall within the inner dust shell radius, which is at ~ 5R (italics)ϰ All of the maser components fall between 1.5R (italics)ϰ and 6R (italics)ϰ. A velocity gradient with position angle was observed in the sparsely filled western region of the maser ring. If interpreted as evidence of shell rotation, this gradient implies a rotational velocity of v (italics) rot (subscirpt) sin i (italics) = 18 km.s⁻¹. The fractional circular and linear polarisations of the maser spots were derived from the Stokes parameter maps. The mean fractional circular polarisation of the masers components was ~ 2 percent and the median fractional linear polarisation was ~ 6 percent, with many spots displaying over ~ 30 percent linear polarisation. The mean circular polarisation implies a magnetic field of ~ 4 G in the SiO maser region if the polarisation is due to Zeeman splitting. Two maser components display a rotation of linear polarisation position angle with velocity, possibly implying a connection between the magnetic field and the velocity field variations in the region of these components.
- Full Text:
- Date Issued: 2006
- Authors: Richter, Laura
- Date: 2006
- Subjects: Very long baseline interferometry , Polarization (Light) , Masers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5498 , http://hdl.handle.net/10962/d1005284
- Description: This thesis reports the calibration, imaging and analysis of one epoch of VLBI observations of the v (italics) = J (italics) = 1-0 transition of SiO towards VY CMa. Full polarisation information was recorded, allowing high resolution synthesis maps of each of the four Stokes parameters to be produced. A total of 81 maser components were extracted from the total intensity map, each approximately 1 mas in size. The emission spans approximately 100 x 80 mas in right ascension and declination and is concentrated to the east. The maser component positions were fitted to a ring of radius ~ 3.2R₊ (italics), or 7.2 x 1O¹⁴ cm for a stellar distance of 1.5 kpc. If the stellar position is assumed to be the centre of this ring then almost all of the maser components fall within the inner dust shell radius, which is at ~ 5R (italics)ϰ All of the maser components fall between 1.5R (italics)ϰ and 6R (italics)ϰ. A velocity gradient with position angle was observed in the sparsely filled western region of the maser ring. If interpreted as evidence of shell rotation, this gradient implies a rotational velocity of v (italics) rot (subscirpt) sin i (italics) = 18 km.s⁻¹. The fractional circular and linear polarisations of the maser spots were derived from the Stokes parameter maps. The mean fractional circular polarisation of the masers components was ~ 2 percent and the median fractional linear polarisation was ~ 6 percent, with many spots displaying over ~ 30 percent linear polarisation. The mean circular polarisation implies a magnetic field of ~ 4 G in the SiO maser region if the polarisation is due to Zeeman splitting. Two maser components display a rotation of linear polarisation position angle with velocity, possibly implying a connection between the magnetic field and the velocity field variations in the region of these components.
- Full Text:
- Date Issued: 2006
The refinement of protective salinity guidelines for South African freshwater resources
- Authors: Slaughter, Andrew Robert
- Date: 2005
- Subjects: Water salinization -- South Africa Salinization -- Control -- South Africa Salinity -- South Africa Freshwater ecology -- South Africa Water resources development -- South Africa Caridina Caridina -- Effect of pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6031 , http://hdl.handle.net/10962/d1006170
- Description: South Africa is an arid country and its growing population is putting freshwater resources under increasing pressure. Natural salinization of freshwater systems is being exacerbated by anthropogenic influences. The National Water Act (No. 36 of 1998) stipulates the need for an ecological Reserve, that quantity and quality of freshwater needed to protect freshwater ecosystems while allowing sustainable use of freshwater resources. Water guidelines do exist in the form of the South African Water Quality Guidelines (DWAF, 1996) and more recently, Jooste and Rossouw (2002) compiled benchmark values for water quality variables marking the boundaries between ecological health classes in the 4-category classification system. Predominantly international toxicity data were used to compile the guidelines and the benchmark values. In addition, there is a paucity of chronic toxicity data nationally and internationally. This thesis showed that it is statistically possible to derive protective chronic endpoints for salinity from acute toxicity data through extrapolation. The Acute to Chronic Ratio (ACR), Two-Step Linear Regression (LRA) and Multi-Factor Probit Analysis (MPA) extrapolation methods were investigated to derive chronic toxicity data from acute toxicity data. The authors of LRA and MPA recommend associating a time independent LCx value in the range of LC₀¸₀₁ to LC₁₀ with a Predicted No Effect Concentration (PNOEC). In addition to published methods, this thesis studied the possibility of equating a time independent LC₅₀ value and subjected to a safety factor of 5 (LRA LC₅₀/5), to the PNOEC. Extrapolated chronic toxicity data where the toxicants are NaCl and Na₂SO₄ were derived for indigenous South African macroinvertebrates. NaCl and Na₂SO₄ are salts associated with salinisation in South Africa. In addition, a chronic salinity toxicity test protocol for an indigenous South African aquatic macroinvertebrate was designed and chronic toxicity test were performed using NaCl and Na₂SO₄ as toxicants. The experimental chronic toxicity data produced were used to validate results from the acute to chronic extrapolation methods. Extrapolated chronic toxicity data were inputted into Species Sensitivity Distribution curves, and concentrations that were predicted to protect 95 % of species (PC95) were compared to the sub-lethality benchmarks proposed by Jooste and Rossouw (2002) for NaCl and Na₂SO₄. This study concluded that the LRA LC₅₀/5 extrapolation method is the most protective and accurate and proposed that LRA replace the ACR method in future guideline development for inorganic salts.
- Full Text:
- Date Issued: 2005
- Authors: Slaughter, Andrew Robert
- Date: 2005
- Subjects: Water salinization -- South Africa Salinization -- Control -- South Africa Salinity -- South Africa Freshwater ecology -- South Africa Water resources development -- South Africa Caridina Caridina -- Effect of pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:6031 , http://hdl.handle.net/10962/d1006170
- Description: South Africa is an arid country and its growing population is putting freshwater resources under increasing pressure. Natural salinization of freshwater systems is being exacerbated by anthropogenic influences. The National Water Act (No. 36 of 1998) stipulates the need for an ecological Reserve, that quantity and quality of freshwater needed to protect freshwater ecosystems while allowing sustainable use of freshwater resources. Water guidelines do exist in the form of the South African Water Quality Guidelines (DWAF, 1996) and more recently, Jooste and Rossouw (2002) compiled benchmark values for water quality variables marking the boundaries between ecological health classes in the 4-category classification system. Predominantly international toxicity data were used to compile the guidelines and the benchmark values. In addition, there is a paucity of chronic toxicity data nationally and internationally. This thesis showed that it is statistically possible to derive protective chronic endpoints for salinity from acute toxicity data through extrapolation. The Acute to Chronic Ratio (ACR), Two-Step Linear Regression (LRA) and Multi-Factor Probit Analysis (MPA) extrapolation methods were investigated to derive chronic toxicity data from acute toxicity data. The authors of LRA and MPA recommend associating a time independent LCx value in the range of LC₀¸₀₁ to LC₁₀ with a Predicted No Effect Concentration (PNOEC). In addition to published methods, this thesis studied the possibility of equating a time independent LC₅₀ value and subjected to a safety factor of 5 (LRA LC₅₀/5), to the PNOEC. Extrapolated chronic toxicity data where the toxicants are NaCl and Na₂SO₄ were derived for indigenous South African macroinvertebrates. NaCl and Na₂SO₄ are salts associated with salinisation in South Africa. In addition, a chronic salinity toxicity test protocol for an indigenous South African aquatic macroinvertebrate was designed and chronic toxicity test were performed using NaCl and Na₂SO₄ as toxicants. The experimental chronic toxicity data produced were used to validate results from the acute to chronic extrapolation methods. Extrapolated chronic toxicity data were inputted into Species Sensitivity Distribution curves, and concentrations that were predicted to protect 95 % of species (PC95) were compared to the sub-lethality benchmarks proposed by Jooste and Rossouw (2002) for NaCl and Na₂SO₄. This study concluded that the LRA LC₅₀/5 extrapolation method is the most protective and accurate and proposed that LRA replace the ACR method in future guideline development for inorganic salts.
- Full Text:
- Date Issued: 2005
Professional development in environmental education in Zanzibar, Tanzania: distances encountered in a semi-distance learning course
- Authors: Heylings, Phillippa Frances
- Date: 2000
- Subjects: Environmental education -- Tanzania -- Zanzibar Distance education -- Tanzania -- Zanzibar Environmental education Distance education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1715 , http://hdl.handle.net/10962/d1003598
- Description: In Zanzibar, in 1995, opportunities for professional development in environmental education were minimal. Yet the demand for professional development was high, especially because of an emphasis on formal qualifications in the country. Credibility was afforded to forms of professional development, aimed at creating more ‘experts’. Ongoing environmental education practice was not achieving its objectives. Into this setting, which was culturally and socio-politically different from the South African context where it was developed, I introduced the Rhodes University Certificate and Gold Fields Participatory Course in Environmental Education (RU/GF); a non-formal, counter-hegemonic course which encouraged critical reflection on the dominant orientations to environmental education practice – including professional development. I used critical ethnographic and action research methods to explore my praxiological interest, the adaptation of the RU/GF curriculum to the Zanzibar context. During the research process, a decision was made to formally accredit the RU/GF course. This decision did not alter the course orientation or the learning process but opened up possibilities for future curriculum development processes. It allowed the students both a formal qualification necessary for status and promotion, and participation in a learning process that challenged the dominant paradigm on professional development and status from within the socio-political context. The research took on a reflexive orientation to research and environmental education. Through a dialectical development of theory, method and results, several important issues emerged. These deal with the ‘distances’ encountered in attempting to address some of the perceived dichotomies in professional development in environmental education through semi-distance learning: the distances between status and learning; the need for career upgrading and the type of learning considered appropriate for professional development in environmental education; the non-quantifiable aims associated with a reflexive orientation to professional development and formal assessment demands for measurable criteria; the democratisation of open-entry courses and the elitism of restricted access; the focus on individual growth and the attainment of a normative grade; theory and practice; and finally distances between learner, text and language. The research supports similar findings emerging from evaluation of the RU/GF course in South Africa and resonates with, and contributes to, issues concerning professional development in environmental education being considered internationally.
- Full Text:
- Date Issued: 2000
- Authors: Heylings, Phillippa Frances
- Date: 2000
- Subjects: Environmental education -- Tanzania -- Zanzibar Distance education -- Tanzania -- Zanzibar Environmental education Distance education
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1715 , http://hdl.handle.net/10962/d1003598
- Description: In Zanzibar, in 1995, opportunities for professional development in environmental education were minimal. Yet the demand for professional development was high, especially because of an emphasis on formal qualifications in the country. Credibility was afforded to forms of professional development, aimed at creating more ‘experts’. Ongoing environmental education practice was not achieving its objectives. Into this setting, which was culturally and socio-politically different from the South African context where it was developed, I introduced the Rhodes University Certificate and Gold Fields Participatory Course in Environmental Education (RU/GF); a non-formal, counter-hegemonic course which encouraged critical reflection on the dominant orientations to environmental education practice – including professional development. I used critical ethnographic and action research methods to explore my praxiological interest, the adaptation of the RU/GF curriculum to the Zanzibar context. During the research process, a decision was made to formally accredit the RU/GF course. This decision did not alter the course orientation or the learning process but opened up possibilities for future curriculum development processes. It allowed the students both a formal qualification necessary for status and promotion, and participation in a learning process that challenged the dominant paradigm on professional development and status from within the socio-political context. The research took on a reflexive orientation to research and environmental education. Through a dialectical development of theory, method and results, several important issues emerged. These deal with the ‘distances’ encountered in attempting to address some of the perceived dichotomies in professional development in environmental education through semi-distance learning: the distances between status and learning; the need for career upgrading and the type of learning considered appropriate for professional development in environmental education; the non-quantifiable aims associated with a reflexive orientation to professional development and formal assessment demands for measurable criteria; the democratisation of open-entry courses and the elitism of restricted access; the focus on individual growth and the attainment of a normative grade; theory and practice; and finally distances between learner, text and language. The research supports similar findings emerging from evaluation of the RU/GF course in South Africa and resonates with, and contributes to, issues concerning professional development in environmental education being considered internationally.
- Full Text:
- Date Issued: 2000
The effects of particle precipitation on the ionosphere in the South Atlantic Anomaly Region
- Authors: Haggard, Raymond
- Date: 1994
- Subjects: Precipitation (Chemistry) Ionosphere Ionospheric electron density
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5463 , http://hdl.handle.net/10962/d1005248
- Description: The first ground based observations of aeronomic phenomena in the South Atlantic Anomaly Region are presented. These data show that enhancements in foF2 and foE can be directly attributed to precipitated electron energy fluxes in the Anomaly Region. The regular occurrence of particle induced sporadic-E ionization is also presented together with the first measurable 391.4 nm airglow radiation of about 16 R. The first comprehensive survey of energy fluxes carried by energetic particles using satellites is also presented for both daytime and nighttime as well as the seasonal fluctuations. We found that the nocturnally precipitated electron energy fluxes varied between 1 x 10⁻⁴ and 38 x 10⁻⁴ erg cm²s⁻¹, depending upon magnetic activity and season, whereas the daytime precipitated electron energy fluxes tended to vary between 1 x 10⁻³ and 8 x 10⁻³ erg cm⁻²s⁻¹, with a tendency to decrease during magnetically active periods. Electron density and temperature contours as well as NO⁺ and 0⁺ ions contours for nighttime are also presented. The main conclusion of the study is that precipitating electrons provide a significant and sometimes dominant source of ionization in the ionosphere over the South Atlantic Anomaly Region.
- Full Text:
- Date Issued: 1994
- Authors: Haggard, Raymond
- Date: 1994
- Subjects: Precipitation (Chemistry) Ionosphere Ionospheric electron density
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5463 , http://hdl.handle.net/10962/d1005248
- Description: The first ground based observations of aeronomic phenomena in the South Atlantic Anomaly Region are presented. These data show that enhancements in foF2 and foE can be directly attributed to precipitated electron energy fluxes in the Anomaly Region. The regular occurrence of particle induced sporadic-E ionization is also presented together with the first measurable 391.4 nm airglow radiation of about 16 R. The first comprehensive survey of energy fluxes carried by energetic particles using satellites is also presented for both daytime and nighttime as well as the seasonal fluctuations. We found that the nocturnally precipitated electron energy fluxes varied between 1 x 10⁻⁴ and 38 x 10⁻⁴ erg cm²s⁻¹, depending upon magnetic activity and season, whereas the daytime precipitated electron energy fluxes tended to vary between 1 x 10⁻³ and 8 x 10⁻³ erg cm⁻²s⁻¹, with a tendency to decrease during magnetically active periods. Electron density and temperature contours as well as NO⁺ and 0⁺ ions contours for nighttime are also presented. The main conclusion of the study is that precipitating electrons provide a significant and sometimes dominant source of ionization in the ionosphere over the South Atlantic Anomaly Region.
- Full Text:
- Date Issued: 1994
A study of petrol and diesel fuel blends with special reference to their thermodynamic properties and phase equilibria
- Authors: Heyward, Caroline
- Date: 1986
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21167 , http://hdl.handle.net/10962/6695
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols. Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application.
- Full Text:
- Date Issued: 1986
- Authors: Heyward, Caroline
- Date: 1986
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21167 , http://hdl.handle.net/10962/6695
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols. Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application.
- Full Text:
- Date Issued: 1986
A study of petrol and diesel fuel blends with special reference to their thermodynamic propeties and phase equilibria
- Authors: Hayward, Caroline
- Date: 1986
- Subjects: Gasoline , Diesel fuels , Thermodynamics , Liquid-liquid equilibrium , Alcohol as fuel
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4065 , http://hdl.handle.net/10962/d1004902 , Gasoline , Diesel fuels , Thermodynamics , Liquid-liquid equilibrium , Alcohol as fuel
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols . Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application. , KMBT_363
- Full Text:
- Date Issued: 1986
- Authors: Hayward, Caroline
- Date: 1986
- Subjects: Gasoline , Diesel fuels , Thermodynamics , Liquid-liquid equilibrium , Alcohol as fuel
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4065 , http://hdl.handle.net/10962/d1004902 , Gasoline , Diesel fuels , Thermodynamics , Liquid-liquid equilibrium , Alcohol as fuel
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols . Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application. , KMBT_363
- Full Text:
- Date Issued: 1986
The relationship between acquired resistance and transmission of Schistosoma Weinland, 1858, in man and its influences on the prevalence of S Capense (Harley, 1864) and S Mansoni Sambon, 1907, in Southern Rhodesia
- Authors: Clarke, H V de V
- Date: 1965
- Subjects: Platyhelminthes , Schistosoma , Schistosomiasis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5842 , http://hdl.handle.net/10962/d1010500 , Platyhelminthes , Schistosoma , Schistosomiasis
- Description: Bilharziasis ranks with Tuberculosis and Malaria as the three most important endemic diseases of man in Rhodesia. The prominence given to bilharziasis in the endemic diseases pattern arises from its high prevalence, particularly in the African population. It is probable that bilharziasis was endemic in the country even prior to the arrival in the conntry of the European settlers in 1890, but it was not until Orpen (1915) described the results of a small survey that local infections were proven. He reported 182 (31 percent) urinary infections in 592 African prisoners examined in the Salisbury gaol. In the ensuing 15 years there was only scanty evidence of the prevalence of the disease. However, in the decade 1931 to 1940 the Annual Public Health Reports of Southern Rhodesia indicated increasing prevalence, and this stimulated interest in the problem and led to the establishment in 1939 of a specialised laboratory to study the parasites causing the disease. The unpublished records of this laboratory indicate that in more recent years the disease has increased not only in prevalence but also in its intensity in infected individuals. Surveys show that the urinary form of the disease is more widespread than the intestinal form. Both forms are becoming more prevalent but the rapid increase of the latter, considered by most authorities to be the more severe, indicates that a greater importance must be accorded to it in the future. Introduction, p. 1.
- Full Text:
- Date Issued: 1965
- Authors: Clarke, H V de V
- Date: 1965
- Subjects: Platyhelminthes , Schistosoma , Schistosomiasis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5842 , http://hdl.handle.net/10962/d1010500 , Platyhelminthes , Schistosoma , Schistosomiasis
- Description: Bilharziasis ranks with Tuberculosis and Malaria as the three most important endemic diseases of man in Rhodesia. The prominence given to bilharziasis in the endemic diseases pattern arises from its high prevalence, particularly in the African population. It is probable that bilharziasis was endemic in the country even prior to the arrival in the conntry of the European settlers in 1890, but it was not until Orpen (1915) described the results of a small survey that local infections were proven. He reported 182 (31 percent) urinary infections in 592 African prisoners examined in the Salisbury gaol. In the ensuing 15 years there was only scanty evidence of the prevalence of the disease. However, in the decade 1931 to 1940 the Annual Public Health Reports of Southern Rhodesia indicated increasing prevalence, and this stimulated interest in the problem and led to the establishment in 1939 of a specialised laboratory to study the parasites causing the disease. The unpublished records of this laboratory indicate that in more recent years the disease has increased not only in prevalence but also in its intensity in infected individuals. Surveys show that the urinary form of the disease is more widespread than the intestinal form. Both forms are becoming more prevalent but the rapid increase of the latter, considered by most authorities to be the more severe, indicates that a greater importance must be accorded to it in the future. Introduction, p. 1.
- Full Text:
- Date Issued: 1965
Construction of a wide-frequency range double heterodyne conductance bridge and its use in the investigation of polarisation errors in conductance measurements
- Authors: Govinden, Herby Silvester
- Date: 1961
- Subjects: Electrodynamics Electrolytes -- Conductivity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5522 , http://hdl.handle.net/10962/d1012074
- Description: (1) Developments in a.c. conductance techniques during the past ninety years have been reviewed, and a brief outline is given of the older theories regarding electrolytic polarisation. (2) A conductance bridge - incorporating the double heterodyne principle - has been constructed, capable of giving resistance readings to an accuracy of 0.01% over a range of frequencies covering the best part of 100 kc/s. It has also been found possible to calibrate the oscillator so that frequency settings can be guaranteed to an accuracy of , at least, 0.1% in the range: 2 kc/S to 50 kc/S. (3) The Wheatstone Bridge Network has been slightly modified to enable measurements at the high frequencies. (4) Resistances in the measuring arm of the bridge have been calibrated 'in situ' by the method of intercomparison. (5) A brief description is given of the modern theories regarding electrode processes and modern methods of eliminating electrode effects. (6) Two types of conductance cells, with bright Pt electrodes, have been used to carry out measurements on potassium chloride solutions: (a) Thomas- Gledhill Cell (b) Nichol-Fuoss Cell. The latter incorporates concentric, cylindrical electrodes with the lead to the outer electrode acting as an electrical shield for the lead to the inner electrode. This cell was constructed and used for the first time in this laboratory. (7) From resistance-frequency graphs plotted, it is shown that the Jones and Christian extrapolation procedure cannot be applied (with any degree of confidence) to obtain the true resistance, when measurements are effected over an extended range of frequencies. (8) The method of resistance-reactance diagrams is discussed and applied to various networks of resistances and capacitances. (9) By drawing resistance-reactance diagrams for the experimental readings obtained, equivalent circuits have been derived - for all the solutions investigated in the N-F cell, and for the approx. O.OlD solution in the T-G cell - which approximate to cell behaviour in the range: 500 c/s to 75 kc/s. The less concentrated solutions in the T-G cell show peculiar behaviour at the high frequencies. (10) Probable reasons are advanced for deviations from linearity on resistance-frequency graphs. (11) A new method is proposed for determining the true resistance of solutions measured in cells of the N-F type. Summary, p. 166-167.
- Full Text:
- Date Issued: 1961
- Authors: Govinden, Herby Silvester
- Date: 1961
- Subjects: Electrodynamics Electrolytes -- Conductivity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5522 , http://hdl.handle.net/10962/d1012074
- Description: (1) Developments in a.c. conductance techniques during the past ninety years have been reviewed, and a brief outline is given of the older theories regarding electrolytic polarisation. (2) A conductance bridge - incorporating the double heterodyne principle - has been constructed, capable of giving resistance readings to an accuracy of 0.01% over a range of frequencies covering the best part of 100 kc/s. It has also been found possible to calibrate the oscillator so that frequency settings can be guaranteed to an accuracy of , at least, 0.1% in the range: 2 kc/S to 50 kc/S. (3) The Wheatstone Bridge Network has been slightly modified to enable measurements at the high frequencies. (4) Resistances in the measuring arm of the bridge have been calibrated 'in situ' by the method of intercomparison. (5) A brief description is given of the modern theories regarding electrode processes and modern methods of eliminating electrode effects. (6) Two types of conductance cells, with bright Pt electrodes, have been used to carry out measurements on potassium chloride solutions: (a) Thomas- Gledhill Cell (b) Nichol-Fuoss Cell. The latter incorporates concentric, cylindrical electrodes with the lead to the outer electrode acting as an electrical shield for the lead to the inner electrode. This cell was constructed and used for the first time in this laboratory. (7) From resistance-frequency graphs plotted, it is shown that the Jones and Christian extrapolation procedure cannot be applied (with any degree of confidence) to obtain the true resistance, when measurements are effected over an extended range of frequencies. (8) The method of resistance-reactance diagrams is discussed and applied to various networks of resistances and capacitances. (9) By drawing resistance-reactance diagrams for the experimental readings obtained, equivalent circuits have been derived - for all the solutions investigated in the N-F cell, and for the approx. O.OlD solution in the T-G cell - which approximate to cell behaviour in the range: 500 c/s to 75 kc/s. The less concentrated solutions in the T-G cell show peculiar behaviour at the high frequencies. (10) Probable reasons are advanced for deviations from linearity on resistance-frequency graphs. (11) A new method is proposed for determining the true resistance of solutions measured in cells of the N-F type. Summary, p. 166-167.
- Full Text:
- Date Issued: 1961
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