Photosynthetic and growth responses of C3 and C4 grasses to short- duration sunflecks and resultant consequences for their performance in understory environments
- Authors: Adams, Claire Elizabeth
- Date: 2017
- Subjects: Understory plants -- Effect of light on , Grasses -- Effect of light on -- South Africa , Erharta -- Effect of light on , Brachiara -- Effect of light on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5016 , vital:20753
- Description: Low C4 grass species abundance in understory environments is thought to be as a result of their high-light requirements, lack of photosynthetic advantage relative to C3 species in cooler environments, and an inability to adequately utilise sunflecks. This study sets out to investigate this theory, hypothesizing that C3 grass species outperform C4 grass species under the canopy, not as a result of quantum efficiency temperature effects, but as a result of C4 species inability to utilize short-duration sunflecks. Short sunflecks could result in a breakdown in assimilate movement between the mesophyll (MSC) and bundle sheath (BSC) cells. The role of BSC leakiness, stomata and PSII efficiency on the ability of C3 and C4 Alloteropsis semialata to utilize short-duration sunflecks was investigated using gaseous exchange and chlorophyll fluorescence techniques, while the growth of both subspecies under a simulated flecking-light environment tested whether these measured responses translated into effects on growth. As C3 grasses are known to possess higher levels of stomatal conductance in relation to C4 species, results showed that C3 A. semialata was able to utilize short-duration sunflecks as a result of increased stomatal conductance and an ability to induce photosynthesis under various light flecking conditions. In contrast, C4 A. semialata was unable to utilize sunflecks possibly as a result of energetic limitations of the carboxylation mechanism (PSII) and not because of increased bundle sheath leakiness. These photosynthetic responses translated into growth differences when both types were grown in an artificially flecking light environment. The photosynthetic differences noted for C3 and C4 A.semialata were also evident in shade adapted understory grasses; Erharta erecta (C3), Dactylotenium australe (C4) and Brachiaria chusqueoides (C4). As photosynthetic induction was marginally more rapid in all species relative to A. semialata it suggests some degree of adaptation in shade grasses, however the inability of the C4 species to utilise short sunflecks remained. As a result, it was hypothesized that C3 shade adapted E. erecta and C4 B. chusqueoides, co-inhabiting the same forest understory, are able to do so because of differences in light micro-environments associated with each species. However, canopy openness and light profiles determined for theses micro-climates showed no differences and that both species have persisted within a relatively stable understory environment. The coexistence was possible as the understory was supplied with a significant proportion of its daily light in flecks sufficiently long as to not compromise C4 productivity. A survey of 10 species of grasses under various canopy densities and in the open showed a strong negative linear relationship between canopy openness and the rate at which photosynthesis was induced by flecking light, which has not been shown before. This did not result from the phylogenetic relationship between species and could be shown for a single species (E. erecta) growing in a range of light environments. This demonstrates that C4 grasses, despite adaptation, would be limited from sunfleck environments if a significant proportion of the daily light available consists of flecks of short-duration. The generation of such environments may occur as a result of woody thickening and could help explain the observed decline in C4 grasses under these conditions.
- Full Text:
- Date Issued: 2017
- Authors: Adams, Claire Elizabeth
- Date: 2017
- Subjects: Understory plants -- Effect of light on , Grasses -- Effect of light on -- South Africa , Erharta -- Effect of light on , Brachiara -- Effect of light on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5016 , vital:20753
- Description: Low C4 grass species abundance in understory environments is thought to be as a result of their high-light requirements, lack of photosynthetic advantage relative to C3 species in cooler environments, and an inability to adequately utilise sunflecks. This study sets out to investigate this theory, hypothesizing that C3 grass species outperform C4 grass species under the canopy, not as a result of quantum efficiency temperature effects, but as a result of C4 species inability to utilize short-duration sunflecks. Short sunflecks could result in a breakdown in assimilate movement between the mesophyll (MSC) and bundle sheath (BSC) cells. The role of BSC leakiness, stomata and PSII efficiency on the ability of C3 and C4 Alloteropsis semialata to utilize short-duration sunflecks was investigated using gaseous exchange and chlorophyll fluorescence techniques, while the growth of both subspecies under a simulated flecking-light environment tested whether these measured responses translated into effects on growth. As C3 grasses are known to possess higher levels of stomatal conductance in relation to C4 species, results showed that C3 A. semialata was able to utilize short-duration sunflecks as a result of increased stomatal conductance and an ability to induce photosynthesis under various light flecking conditions. In contrast, C4 A. semialata was unable to utilize sunflecks possibly as a result of energetic limitations of the carboxylation mechanism (PSII) and not because of increased bundle sheath leakiness. These photosynthetic responses translated into growth differences when both types were grown in an artificially flecking light environment. The photosynthetic differences noted for C3 and C4 A.semialata were also evident in shade adapted understory grasses; Erharta erecta (C3), Dactylotenium australe (C4) and Brachiaria chusqueoides (C4). As photosynthetic induction was marginally more rapid in all species relative to A. semialata it suggests some degree of adaptation in shade grasses, however the inability of the C4 species to utilise short sunflecks remained. As a result, it was hypothesized that C3 shade adapted E. erecta and C4 B. chusqueoides, co-inhabiting the same forest understory, are able to do so because of differences in light micro-environments associated with each species. However, canopy openness and light profiles determined for theses micro-climates showed no differences and that both species have persisted within a relatively stable understory environment. The coexistence was possible as the understory was supplied with a significant proportion of its daily light in flecks sufficiently long as to not compromise C4 productivity. A survey of 10 species of grasses under various canopy densities and in the open showed a strong negative linear relationship between canopy openness and the rate at which photosynthesis was induced by flecking light, which has not been shown before. This did not result from the phylogenetic relationship between species and could be shown for a single species (E. erecta) growing in a range of light environments. This demonstrates that C4 grasses, despite adaptation, would be limited from sunfleck environments if a significant proportion of the daily light available consists of flecks of short-duration. The generation of such environments may occur as a result of woody thickening and could help explain the observed decline in C4 grasses under these conditions.
- Full Text:
- Date Issued: 2017
Apparent digestibility coefficients of feed ingredients and essential amino acid requirements of dusky kob (Argyrosomus japonicus)
- Authors: Adesola, Abidemi Adejoke
- Date: 2017
- Subjects: Amino acids in animal nutrition , Fishes -- Feeding and feeds , Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Nutrition , Argyrosomus -- Nutrition , Argyrosomus japonicus -- Feeding and feeds , Argyrosomus -- Feeding and feeds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/32140 , vital:24014
- Description: Important to the evaluation of potential feed ingredients for inclusion in fish diets should be their digestibility and amino acid requirement so that feeds can be formulated on a digestible basis rather than a gross nutrient basis. This thesis established techniques for faecal collection, the validity of digestibility markers, it determined apparent digestibility coefficients for various novel feed ingredients, and it established the optimal lysine requirement for Argyrosomus japonicus, which was used to estimate each of the essential amino acid requirements by using the ideal protein concept. There were no significant differences in dry matter apparent digestibility coefficients when faeces were collected by stripping (77.0 %), dissection (80.1 %) or settlement (83.5 %). Faecal collection by the settlement method produced the most reliable digestibility data. Apparent digestibility coefficients for dry matter, crude protein and energy calculated using acid-insoluble ash were higher (84.0 %, 93.2 % and 93.0 %, respectively) than those using chromic oxide (55.7 %, 79.1 % and 78.2 %) and titanium dioxide (58.6 %, 79.7 % and 80.5 %). The magnitude of variation in digestibility coefficients obtained using acid-insoluble ash was always lower than that obtained with the other markers. Therefore, acid-insoluble ash was preferred as a dietary marker. Using the above protocol, protein and amino acid digestibility of some animal and plant protein ingredients were evaluated in a series of experiments. The first trial compared the apparent digestibility coefficients of some animal products included as single protein source in the test diets. Apparent protein digestibility values were 84.5 %, 83.8 %, 85.8 % and 83.1 % for fishmeal-prime, fishmeal-standard, poultry meal and pork meal, respectively. Apparent digestibility coefficients for poultry meal were comparable to those of fishmeal, which indicate its potential as a substitute for fishmeal in the diets of A. japonicus. The second trial determined the apparent coefficients of plant and animal protein sources included at 30 % into a practical reference diet (70 %). Apparent protein digestibility ranged from 92.4 % in sunflower meal to 85.5 % in corn gluten meal. Soybean meal is a promising feed ingredient in A. japonicus due to the high apparent digestibility of its protein (92.0 %) and essential amino acid digestibility (mean average 91.4 %). A fundamental assumption in fish feed formulation is that the digestibility of nutrients is additive, i.e., digestibility of a nutrient in one ingredient does not interact with the digestibility of the same nutrient in another ingredient. In the third trial, additivity of feed ingredients was tested using pork meal and poultry meal. The results indicate that the apparent digestibility coefficient of animal protein ingredients could be calculated from compound diets to accurately determine protein and amino acid digestibility in A. japonicus, and possibly other carnivorous fish species. Dietary essential amino acid requirements were determined for juvenile A. japonicus in two trials. A dose-response study was conducted using crystalline lysine to determine the optimal requirement of dietary lysine for A. japonicus. Optimal dietary lysine was estimated at 31.7 g kg-¹ dry diet, corresponding to 73.5 g kg-¹ of dietary protein, based on specific growth rate and broken-line segmented regression analyses. Dietary requirements for other essential amino acids ranged from 22 g kg-¹ (histidine) to 71 g kg-¹ (leucine) crude protein. The results of the present study provided a research tool that could be used to assess and verify the conclusions of earlier dietary work on A. japonicus and in further studies to develop least cost diet formulations for this species. The study also adds to the knowledge of the nutritional requirements of A. japonicus by providing information on the digestibility of plants and animal protein ingredients. It also contributes to future dietary research for this species because this study determines, for the first time, the most suitable methods for investigating the digestibility of raw materials for A. japonicus.
- Full Text:
- Date Issued: 2017
- Authors: Adesola, Abidemi Adejoke
- Date: 2017
- Subjects: Amino acids in animal nutrition , Fishes -- Feeding and feeds , Argyrosomus japonicus , Argyrosomus , Argyrosomus japonicus -- Nutrition , Argyrosomus -- Nutrition , Argyrosomus japonicus -- Feeding and feeds , Argyrosomus -- Feeding and feeds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/32140 , vital:24014
- Description: Important to the evaluation of potential feed ingredients for inclusion in fish diets should be their digestibility and amino acid requirement so that feeds can be formulated on a digestible basis rather than a gross nutrient basis. This thesis established techniques for faecal collection, the validity of digestibility markers, it determined apparent digestibility coefficients for various novel feed ingredients, and it established the optimal lysine requirement for Argyrosomus japonicus, which was used to estimate each of the essential amino acid requirements by using the ideal protein concept. There were no significant differences in dry matter apparent digestibility coefficients when faeces were collected by stripping (77.0 %), dissection (80.1 %) or settlement (83.5 %). Faecal collection by the settlement method produced the most reliable digestibility data. Apparent digestibility coefficients for dry matter, crude protein and energy calculated using acid-insoluble ash were higher (84.0 %, 93.2 % and 93.0 %, respectively) than those using chromic oxide (55.7 %, 79.1 % and 78.2 %) and titanium dioxide (58.6 %, 79.7 % and 80.5 %). The magnitude of variation in digestibility coefficients obtained using acid-insoluble ash was always lower than that obtained with the other markers. Therefore, acid-insoluble ash was preferred as a dietary marker. Using the above protocol, protein and amino acid digestibility of some animal and plant protein ingredients were evaluated in a series of experiments. The first trial compared the apparent digestibility coefficients of some animal products included as single protein source in the test diets. Apparent protein digestibility values were 84.5 %, 83.8 %, 85.8 % and 83.1 % for fishmeal-prime, fishmeal-standard, poultry meal and pork meal, respectively. Apparent digestibility coefficients for poultry meal were comparable to those of fishmeal, which indicate its potential as a substitute for fishmeal in the diets of A. japonicus. The second trial determined the apparent coefficients of plant and animal protein sources included at 30 % into a practical reference diet (70 %). Apparent protein digestibility ranged from 92.4 % in sunflower meal to 85.5 % in corn gluten meal. Soybean meal is a promising feed ingredient in A. japonicus due to the high apparent digestibility of its protein (92.0 %) and essential amino acid digestibility (mean average 91.4 %). A fundamental assumption in fish feed formulation is that the digestibility of nutrients is additive, i.e., digestibility of a nutrient in one ingredient does not interact with the digestibility of the same nutrient in another ingredient. In the third trial, additivity of feed ingredients was tested using pork meal and poultry meal. The results indicate that the apparent digestibility coefficient of animal protein ingredients could be calculated from compound diets to accurately determine protein and amino acid digestibility in A. japonicus, and possibly other carnivorous fish species. Dietary essential amino acid requirements were determined for juvenile A. japonicus in two trials. A dose-response study was conducted using crystalline lysine to determine the optimal requirement of dietary lysine for A. japonicus. Optimal dietary lysine was estimated at 31.7 g kg-¹ dry diet, corresponding to 73.5 g kg-¹ of dietary protein, based on specific growth rate and broken-line segmented regression analyses. Dietary requirements for other essential amino acids ranged from 22 g kg-¹ (histidine) to 71 g kg-¹ (leucine) crude protein. The results of the present study provided a research tool that could be used to assess and verify the conclusions of earlier dietary work on A. japonicus and in further studies to develop least cost diet formulations for this species. The study also adds to the knowledge of the nutritional requirements of A. japonicus by providing information on the digestibility of plants and animal protein ingredients. It also contributes to future dietary research for this species because this study determines, for the first time, the most suitable methods for investigating the digestibility of raw materials for A. japonicus.
- Full Text:
- Date Issued: 2017
Perceptions and livelihood uses of an invasive alien tree (acacia dealbata) by rural communities in the Eastern Cape
- Authors: Agripa, Ngorima
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5326 , vital:20813
- Description: The negative impacts which invasive alien species have on ecosystems are well documented but there is paucity of information on their impacts on rural communities. Due to ecological impacts that may be associated with Acacia dealbata invasions the Agricultural Research Council Plant Protection Institute is considering releasing a biocontrol agent for A. dealbata. The actual social impacts of A. dealbata invasion and control are likely to be related to its importance in rural livelihoods. This thesis reports on the perceptions and livelihood uses of A. dealbata in the Eastern Cape. Three study sites were assessed, Matatiele, Mount Fletcher and Maclear. The study involved 150 household surveys, one focus group discussion and one transect walk at each site, key informant interviews and frequent house visits to acquire reliable data. Results show that 100 % of households in the three sites use Silver Wattle extensively for firewood. In Matatiele 64 %, 72 % in Mount Fletcher and 84 % of households in Maclear use Silver Wattle for fencing. To carve tools 76 % in Matatiele, 76 % in Mount Fletcher and 84 % households in Maclear use Silver Wattle. For medicinal purposes 18 % in Matatiele, 20 % in Mount Fletcher and 16 % in Maclear use Silver Wattle, whilst 78 % in Matatiele, 80 % in Mount Fletcher and 80 % in Maclear use it for fodder purposes. Many respondents felt that Silver Wattle is too abundant within their areas such that it now has many negative impacts associated with it. Perceptions of local people towards A. dealbata are neither static nor uniform, but are influenced by time since the invasion and now abundance of the species. There are no alternatives which provide the same services provided by Silver Wattle. Benefits and constraints due to A. dealbata invasion are experienced by everyone irrespective of wealth and gender. In conclusion, Silver Wattle is a valuable resource to these rural communities, but increasing abundance is incurring high costs to grazing resources and landscape accessibility.
- Full Text:
- Date Issued: 2017
- Authors: Agripa, Ngorima
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/5326 , vital:20813
- Description: The negative impacts which invasive alien species have on ecosystems are well documented but there is paucity of information on their impacts on rural communities. Due to ecological impacts that may be associated with Acacia dealbata invasions the Agricultural Research Council Plant Protection Institute is considering releasing a biocontrol agent for A. dealbata. The actual social impacts of A. dealbata invasion and control are likely to be related to its importance in rural livelihoods. This thesis reports on the perceptions and livelihood uses of A. dealbata in the Eastern Cape. Three study sites were assessed, Matatiele, Mount Fletcher and Maclear. The study involved 150 household surveys, one focus group discussion and one transect walk at each site, key informant interviews and frequent house visits to acquire reliable data. Results show that 100 % of households in the three sites use Silver Wattle extensively for firewood. In Matatiele 64 %, 72 % in Mount Fletcher and 84 % of households in Maclear use Silver Wattle for fencing. To carve tools 76 % in Matatiele, 76 % in Mount Fletcher and 84 % households in Maclear use Silver Wattle. For medicinal purposes 18 % in Matatiele, 20 % in Mount Fletcher and 16 % in Maclear use Silver Wattle, whilst 78 % in Matatiele, 80 % in Mount Fletcher and 80 % in Maclear use it for fodder purposes. Many respondents felt that Silver Wattle is too abundant within their areas such that it now has many negative impacts associated with it. Perceptions of local people towards A. dealbata are neither static nor uniform, but are influenced by time since the invasion and now abundance of the species. There are no alternatives which provide the same services provided by Silver Wattle. Benefits and constraints due to A. dealbata invasion are experienced by everyone irrespective of wealth and gender. In conclusion, Silver Wattle is a valuable resource to these rural communities, but increasing abundance is incurring high costs to grazing resources and landscape accessibility.
- Full Text:
- Date Issued: 2017
Negotiating the line between information and panic: a case study of vanguard’s coverage of the ebola outbreak in Nigeria
- Authors: Akingbade, Olutobi Elijah
- Date: 2017
- Subjects: Digital media -- Marketing , Marketing -- Technological innovations , Internet marketing , Carbonated beverages -- Marketing , Coca Cola (Trademark) -- Marketing , Social media -- Economic aspects , Soft drink industry -- Internet marketing , Health behavior in adolescence , Advertising -- Carbonated beverages , Obesity in adolescence , Drinking behavior
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/5903 , vital:20986
- Description: This study titled ‘Negotiating the line between information and panic: A case study of Vanguard’s coverage of the Ebola Outbreak in Nigeria’ investigates and evaluates Vanguard’s coverage of the 2014 Ebola Virus Disease (EVD) outbreak in Nigeria. This study was conducted to understand how Vanguard negotiated the line between the dissemination of actual EVD information and the possibility of creating panic and fear during the coverage of the outbreak. Using qualitative content analysis and interview embedded within a qualitative research design, the study was carried out against the backdrop of relevant literature that asserts that the mass media is an important carrier, prime mover and producer of tensions, anxieties, fears and panics while the print media specifically is argued to have as part of its history the business of irrational fear mongering and the creation of panic about social problems. Vanguard, rated as one of the ten largest newspapers in Nigeria, was purposively selected for this study. Vanguard did substantial reporting and dissemination of the 2014 EVD outbreak and it was possible to draw on the availability and accessibility of the electronic archives of the EVD articles. Using the theory of moral panic, the normative theories of the media and theories about essential constituents of journalism culture as a theoretical framework, the study reveals that Vanguard’s coverage of the 2014 EVD outbreak was challenging and more demanding compared to coverage of previous outbreaks of viral diseases in Nigeria by the print medium. The study shows that lack of sufficient understanding of the science that underlies EVD, the initial exclusion of the media from the national response to contain the outbreak, and the lack of sufficient proactive measures by government and the print medium were powerful factors in how the epidemic was reported. The study also shows an interesting dimension in Vanguard’s early and latter coverage of the EVD outbreak while it lasted in Nigeria. This dimension reveals a high number of EVD articles with the propensity to inspire fear and panic in the early days of the coverage compared to EVD articles with the propensity to douse fear and panic in the early and latter days of the outbreak. The study shows that while the challenges encountered stem from Ebola’s mode of transmission, lack of scientific and medically proven cure and early coverage amidst uncertainties, the inherent tensions and anxieties that characterised the outbreak coupled with Vanguard’s fire brigade approach led to the relatively high number of EVD articles with the propensity to inspire fear and panic. The study recommends the mass media’s inclusion in national responses to epidemics and ongoing training for health journalists to update their knowledge base about emerging and infectious diseases. The study also recommends for further study a reception analysis to enhance the socio-cultural understanding of how the EVD articles were received.
- Full Text:
- Date Issued: 2017
- Authors: Akingbade, Olutobi Elijah
- Date: 2017
- Subjects: Digital media -- Marketing , Marketing -- Technological innovations , Internet marketing , Carbonated beverages -- Marketing , Coca Cola (Trademark) -- Marketing , Social media -- Economic aspects , Soft drink industry -- Internet marketing , Health behavior in adolescence , Advertising -- Carbonated beverages , Obesity in adolescence , Drinking behavior
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/5903 , vital:20986
- Description: This study titled ‘Negotiating the line between information and panic: A case study of Vanguard’s coverage of the Ebola Outbreak in Nigeria’ investigates and evaluates Vanguard’s coverage of the 2014 Ebola Virus Disease (EVD) outbreak in Nigeria. This study was conducted to understand how Vanguard negotiated the line between the dissemination of actual EVD information and the possibility of creating panic and fear during the coverage of the outbreak. Using qualitative content analysis and interview embedded within a qualitative research design, the study was carried out against the backdrop of relevant literature that asserts that the mass media is an important carrier, prime mover and producer of tensions, anxieties, fears and panics while the print media specifically is argued to have as part of its history the business of irrational fear mongering and the creation of panic about social problems. Vanguard, rated as one of the ten largest newspapers in Nigeria, was purposively selected for this study. Vanguard did substantial reporting and dissemination of the 2014 EVD outbreak and it was possible to draw on the availability and accessibility of the electronic archives of the EVD articles. Using the theory of moral panic, the normative theories of the media and theories about essential constituents of journalism culture as a theoretical framework, the study reveals that Vanguard’s coverage of the 2014 EVD outbreak was challenging and more demanding compared to coverage of previous outbreaks of viral diseases in Nigeria by the print medium. The study shows that lack of sufficient understanding of the science that underlies EVD, the initial exclusion of the media from the national response to contain the outbreak, and the lack of sufficient proactive measures by government and the print medium were powerful factors in how the epidemic was reported. The study also shows an interesting dimension in Vanguard’s early and latter coverage of the EVD outbreak while it lasted in Nigeria. This dimension reveals a high number of EVD articles with the propensity to inspire fear and panic in the early days of the coverage compared to EVD articles with the propensity to douse fear and panic in the early and latter days of the outbreak. The study shows that while the challenges encountered stem from Ebola’s mode of transmission, lack of scientific and medically proven cure and early coverage amidst uncertainties, the inherent tensions and anxieties that characterised the outbreak coupled with Vanguard’s fire brigade approach led to the relatively high number of EVD articles with the propensity to inspire fear and panic. The study recommends the mass media’s inclusion in national responses to epidemics and ongoing training for health journalists to update their knowledge base about emerging and infectious diseases. The study also recommends for further study a reception analysis to enhance the socio-cultural understanding of how the EVD articles were received.
- Full Text:
- Date Issued: 2017
Investigating the use of models to develop Grade 8 learners’ conceptual understanding of and procedural fluency with fractions
- Authors: Albin, Simon
- Date: 2017
- Subjects: Fractions -- Study and teaching (Secondary) -- Namibia , Mathematics -- Study and teaching (Secondary) -- Namibia , Information visualization , Visual learning -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/36288 , vital:24537
- Description: Both my teaching experience and literature of this research study strongly suggested that fractions are difficult to teach and learn across the globe generally, and Namibia in particular. One of the identified contributing factors was teaching fractions by focusing on procedures and not the conceptual understanding. Therefore, this research project developed and implemented an intervention in order to experiment and suggest an alternative teaching approach of fractions using models. The purpose of this research was to: “Investigate the use of models to develop Grade 8 learners’ conceptual understanding of and procedural fluency with fractions”. This investigation had three areas of focus. Firstly, the study investigated the nature of learners’ conceptual understanding of and procedural fluency with fractions before the teaching intervention, by means of administering a pre-test and pre-interview and analysing learners’ responses. Secondly, the study investigated the changes in learners’ conceptual understanding of and procedural fluency with fractions after the teaching intervention, by means of administering a post-test, post-interviews and recall interviews, and analysing learners’ responses. Thirdly, this study investigated the possible influence of the teaching intervention on the changes in learners’ conceptual understanding of and procedural fluency with fractions by analysing the lesson videos and learners’ worksheets, and describe their critical interaction. This study was conducted at a multicultural urban secondary school located in the Oshikoto Region, Namibia. The sample consisted of 12 Grade 8 mathematics learners whose age ranged from 13-16 years old. A purposive sampling method was employed to select both the research site and participants. This research is framed as a case study, and is grounded within the interpretive paradigm and qualitative research. This research revealed that these learners displayed conceptual and procedural difficulties in their engagement with fraction models and fraction symbols, before the teaching intervention. Conceptually, the study found that these learners read fractions using inappropriate names; and learners did not identify the whole unit in the models and therefore identified fractions represented by the fraction models using different forms of inappropriate fraction symbols. Procedurally, the study found that these learners compared and ordered fractions inappropriately using the sizes of the numerators and denominators separately; and learners used the lowest common denominator method inappropriately for adding fractions with different denominators. The research also suggested conceptual and procedural changes in learners’ conceptual understanding of and procedural fluency with fractions and that the intervention seemed to help learners to engage better with fraction models and fraction symbols. Conceptually, the findings suggested that the intervention using area models and number lines, seemed to help these learners to read fractions using appropriate names; to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit. Procedurally, the learners compared and ordered fractions appropriately using either equal fraction bars, equal number lines, benchmarking or rules for comparing and ordering fractions with the same numerator or denominator; and learners used equal fraction bars to visually represent the lowest common denominator method and to recognise that only equally sized units can be counted together. This research identified four factors as possible influences of the teaching intervention. These factors are namely: identifying both fraction symbols and appropriate fraction names to see fractions as relational numbers; prompting to partition whole units of the fraction models and graphically illustrating fraction symbols to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit; graphically illustrating fraction symbols using the models to use equal fraction bars and number lines, benchmarking and rules for comparing; and graphically illustrating fraction denominations using equal fraction bars to recognise that only equally sized units can be counted together. This research strongly suggests that the effective use of models has the potential to develop learners’ conceptual understanding of and procedural fluency with fractions in a number of ways.
- Full Text:
- Date Issued: 2017
- Authors: Albin, Simon
- Date: 2017
- Subjects: Fractions -- Study and teaching (Secondary) -- Namibia , Mathematics -- Study and teaching (Secondary) -- Namibia , Information visualization , Visual learning -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/36288 , vital:24537
- Description: Both my teaching experience and literature of this research study strongly suggested that fractions are difficult to teach and learn across the globe generally, and Namibia in particular. One of the identified contributing factors was teaching fractions by focusing on procedures and not the conceptual understanding. Therefore, this research project developed and implemented an intervention in order to experiment and suggest an alternative teaching approach of fractions using models. The purpose of this research was to: “Investigate the use of models to develop Grade 8 learners’ conceptual understanding of and procedural fluency with fractions”. This investigation had three areas of focus. Firstly, the study investigated the nature of learners’ conceptual understanding of and procedural fluency with fractions before the teaching intervention, by means of administering a pre-test and pre-interview and analysing learners’ responses. Secondly, the study investigated the changes in learners’ conceptual understanding of and procedural fluency with fractions after the teaching intervention, by means of administering a post-test, post-interviews and recall interviews, and analysing learners’ responses. Thirdly, this study investigated the possible influence of the teaching intervention on the changes in learners’ conceptual understanding of and procedural fluency with fractions by analysing the lesson videos and learners’ worksheets, and describe their critical interaction. This study was conducted at a multicultural urban secondary school located in the Oshikoto Region, Namibia. The sample consisted of 12 Grade 8 mathematics learners whose age ranged from 13-16 years old. A purposive sampling method was employed to select both the research site and participants. This research is framed as a case study, and is grounded within the interpretive paradigm and qualitative research. This research revealed that these learners displayed conceptual and procedural difficulties in their engagement with fraction models and fraction symbols, before the teaching intervention. Conceptually, the study found that these learners read fractions using inappropriate names; and learners did not identify the whole unit in the models and therefore identified fractions represented by the fraction models using different forms of inappropriate fraction symbols. Procedurally, the study found that these learners compared and ordered fractions inappropriately using the sizes of the numerators and denominators separately; and learners used the lowest common denominator method inappropriately for adding fractions with different denominators. The research also suggested conceptual and procedural changes in learners’ conceptual understanding of and procedural fluency with fractions and that the intervention seemed to help learners to engage better with fraction models and fraction symbols. Conceptually, the findings suggested that the intervention using area models and number lines, seemed to help these learners to read fractions using appropriate names; to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit. Procedurally, the learners compared and ordered fractions appropriately using either equal fraction bars, equal number lines, benchmarking or rules for comparing and ordering fractions with the same numerator or denominator; and learners used equal fraction bars to visually represent the lowest common denominator method and to recognise that only equally sized units can be counted together. This research identified four factors as possible influences of the teaching intervention. These factors are namely: identifying both fraction symbols and appropriate fraction names to see fractions as relational numbers; prompting to partition whole units of the fraction models and graphically illustrating fraction symbols to identify the whole unit in the fraction models and to develop a sense of the size of fractions in relation to one whole unit; graphically illustrating fraction symbols using the models to use equal fraction bars and number lines, benchmarking and rules for comparing; and graphically illustrating fraction denominations using equal fraction bars to recognise that only equally sized units can be counted together. This research strongly suggests that the effective use of models has the potential to develop learners’ conceptual understanding of and procedural fluency with fractions in a number of ways.
- Full Text:
- Date Issued: 2017
Positioning 'the self': comparative case studies of first generation students' academic identities when home meets campus in a rapidly transforming higher education context
- Authors: Alcock, Andrea
- Date: 2017
- Subjects: First-generation college students -- South Africa , First-generation college students -- South Africa -- Case studies , Social perception -- South Africa , Educational equalization -- South Africa , College students -- South Africa -- Attitudes , College students, Black -- South Africa -- Attitudes , College students, Black -- South Africa -- Psychology
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/6897 , vital:21198
- Description: This research offers an in-depth view of the self-positioning of a sample of seven first generation students in an extended curriculum programme for Arts and Design at the Durban University of Technology. This comparative case study aims to examine how these participants took up, held or resisted positions, during the transitional process of entering a university. The students' responses were elicited in order to explore the development of student academic identity in this stage of late adolescence. Using positioning theory as an analytical framework, a visual methodology was employed to generate data during photo-elicitation interviews. For these, participants were invited to take metaphorical and non-mimetic photographs, in response to the prompt "Take photographs that show you as a student at home and on campus". Themes that surfaced were examined using positioning theory where the storylines, speech acts and rights and duties form the apex points of the positioning triangle that acts as a framework to analyse the participants' narratives. The study revealed the ways in which participants positioned their home communities and thereby developed their own agency. The majority of the participants used their self-positioning in relation to these home communities to build their academic identities. It was evident in the data that certain role models and peers played a significant part in such self-positioning. The rural to urban migration described by some of the participants indicated that the transition students navigated as they developed their academic identities was profound. The university was often perceived in this process as a powerful structure which offered opportunities but could simultaneously be experienced as alienating. Financial challenges added to the complexity of this experience. The development of student academic identity was evident in positioning statements of the participants and, in some cases, a professional identity was revealed. The analysis indicated that the participants were able to use their self-positioning to overcome many of their challenges through the creation of agential power and resilience. Furthermore the emergence of academic identity seemed to give rise to a positive view of 'the self' in relation to the period of transition to university.
- Full Text:
- Date Issued: 2017
- Authors: Alcock, Andrea
- Date: 2017
- Subjects: First-generation college students -- South Africa , First-generation college students -- South Africa -- Case studies , Social perception -- South Africa , Educational equalization -- South Africa , College students -- South Africa -- Attitudes , College students, Black -- South Africa -- Attitudes , College students, Black -- South Africa -- Psychology
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/6897 , vital:21198
- Description: This research offers an in-depth view of the self-positioning of a sample of seven first generation students in an extended curriculum programme for Arts and Design at the Durban University of Technology. This comparative case study aims to examine how these participants took up, held or resisted positions, during the transitional process of entering a university. The students' responses were elicited in order to explore the development of student academic identity in this stage of late adolescence. Using positioning theory as an analytical framework, a visual methodology was employed to generate data during photo-elicitation interviews. For these, participants were invited to take metaphorical and non-mimetic photographs, in response to the prompt "Take photographs that show you as a student at home and on campus". Themes that surfaced were examined using positioning theory where the storylines, speech acts and rights and duties form the apex points of the positioning triangle that acts as a framework to analyse the participants' narratives. The study revealed the ways in which participants positioned their home communities and thereby developed their own agency. The majority of the participants used their self-positioning in relation to these home communities to build their academic identities. It was evident in the data that certain role models and peers played a significant part in such self-positioning. The rural to urban migration described by some of the participants indicated that the transition students navigated as they developed their academic identities was profound. The university was often perceived in this process as a powerful structure which offered opportunities but could simultaneously be experienced as alienating. Financial challenges added to the complexity of this experience. The development of student academic identity was evident in positioning statements of the participants and, in some cases, a professional identity was revealed. The analysis indicated that the participants were able to use their self-positioning to overcome many of their challenges through the creation of agential power and resilience. Furthermore the emergence of academic identity seemed to give rise to a positive view of 'the self' in relation to the period of transition to university.
- Full Text:
- Date Issued: 2017
New spaces and old stories: the Luminance woman, black womanhood and the illusion of the “new” South Africa
- Alweendo, Ndapwa Magano Nelao
- Authors: Alweendo, Ndapwa Magano Nelao
- Date: 2017
- Subjects: Luminance stores (South Africa) , Dhlomo, Khanyi , Dlamini, Judy , Women, Black -- South Africa -- Social life and customes , Women, Black -- South Africa -- Social conditions , Clothing trade -- South Africa , Social classes -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/42619 , vital:25220
- Description: This study examines ideas of black womanhood in post-apartheid South Africa. The opening of the Luminance boutique in 2013, previously owned by South African businesswoman and media mogul Khanyi Dhlomo in Johannesburg’s ultra-exclusive Hyde Park Corner, has been articulated as representing a rupture in the public and private performance of black womanhood. Luminance has positioned itself as a provider of world-class style and beauty and has embraced a narrative of black women’s empowerment in the process. The study is based on narrative semistructured interviews conducted Johannesburg with black women who have shopped at the boutique and women who believe themselves as having a meaningful connection to the store. The literature on black women, both internationally and in South Africa, acknowledges that black women experience multiple and intersecting oppressions of race, class and gender, among others. Located within black feminist theory, the study argues that the Luminance woman does represent some rupture in the historic understanding of black womanhood in South Africa. This woman is an elite player in both the corporate world and the world of luxury consumption, and is certainly entering spaces to which black women have historically been denied access. However, this study argues that there is a danger in reducing this woman to an oversimplified character, allowing responses to her to ignore the complexities of her reality in favour of the simplicity of her story, and ignore the structural socioeconomic challenges that continue to shape the lives of all black women in postapartheid South Africa. In this regard, the Luminance woman, while on the surface appearing to be an empowering new iteration of womanhood that should inspire other black woman, contributes to the erasure of her particular marginal experiences, and the oppression of black women in general. The story of the Luminance women contributes to a narrative of individual hard work and determination that frames her as a respectable example of what the “new” South Africa has delivered for its citizens. This woman is a model example of a South African who has succeeded because she took advantage of the opportunities supposedly afforded to all in the post-1994 era. It is therefore argued that praise of the Luminance woman serves a dual purpose: to reinforce the myth of equal opportunity in South Africa, and to lessen the legitimacy of marginalised groups’ experiences of oppression, especially black women who continue to constitute the poor majority.
- Full Text:
- Date Issued: 2017
- Authors: Alweendo, Ndapwa Magano Nelao
- Date: 2017
- Subjects: Luminance stores (South Africa) , Dhlomo, Khanyi , Dlamini, Judy , Women, Black -- South Africa -- Social life and customes , Women, Black -- South Africa -- Social conditions , Clothing trade -- South Africa , Social classes -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/42619 , vital:25220
- Description: This study examines ideas of black womanhood in post-apartheid South Africa. The opening of the Luminance boutique in 2013, previously owned by South African businesswoman and media mogul Khanyi Dhlomo in Johannesburg’s ultra-exclusive Hyde Park Corner, has been articulated as representing a rupture in the public and private performance of black womanhood. Luminance has positioned itself as a provider of world-class style and beauty and has embraced a narrative of black women’s empowerment in the process. The study is based on narrative semistructured interviews conducted Johannesburg with black women who have shopped at the boutique and women who believe themselves as having a meaningful connection to the store. The literature on black women, both internationally and in South Africa, acknowledges that black women experience multiple and intersecting oppressions of race, class and gender, among others. Located within black feminist theory, the study argues that the Luminance woman does represent some rupture in the historic understanding of black womanhood in South Africa. This woman is an elite player in both the corporate world and the world of luxury consumption, and is certainly entering spaces to which black women have historically been denied access. However, this study argues that there is a danger in reducing this woman to an oversimplified character, allowing responses to her to ignore the complexities of her reality in favour of the simplicity of her story, and ignore the structural socioeconomic challenges that continue to shape the lives of all black women in postapartheid South Africa. In this regard, the Luminance woman, while on the surface appearing to be an empowering new iteration of womanhood that should inspire other black woman, contributes to the erasure of her particular marginal experiences, and the oppression of black women in general. The story of the Luminance women contributes to a narrative of individual hard work and determination that frames her as a respectable example of what the “new” South Africa has delivered for its citizens. This woman is a model example of a South African who has succeeded because she took advantage of the opportunities supposedly afforded to all in the post-1994 era. It is therefore argued that praise of the Luminance woman serves a dual purpose: to reinforce the myth of equal opportunity in South Africa, and to lessen the legitimacy of marginalised groups’ experiences of oppression, especially black women who continue to constitute the poor majority.
- Full Text:
- Date Issued: 2017
In silico analysis of plasmodium falciparum Hsp70-x for potential binding sites and hits
- Authors: Amusengeri, Arnold
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59136 , vital:27435
- Description: Restricted access-thesis embargoed for 1 year - release date April 2019
- Full Text:
- Date Issued: 2017
- Authors: Amusengeri, Arnold
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59136 , vital:27435
- Description: Restricted access-thesis embargoed for 1 year - release date April 2019
- Full Text:
- Date Issued: 2017
The effects of changing western worldviews on morals and ethics in economics: a protestant perspective
- Authors: Appalraju, Nerusha
- Date: 2017
- Subjects: Economics -- Moral and ethical aspects , Neoclassical school of economics , Capitalism -- Religious aspects -- Protestant churches , Feminist economics , Economics -- Religious aspects , Environmental economics -- Moral and ethical aspects , Smith, Adam, 1723-1790 , Weber, Max, 1864-1920
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/32480 , vital:24050
- Description: The World Economics Association held an online conference in 2012 where they published many papers on ethics in economics. The topic of ethics in economics became more serious and popular following the 2008 financial crisis. However the case for a professional code of ethics in economics is difficult to introduce and implement due to the multidisciplinary approach of the discipline. Therefore authors such as Dow (2012), De Martino (2012), Freeman (2012) and Earl (2012) urged economists to start thinking about ethics in economics from a pluralistic view. This thesis studied the effects of changing Western worldviews on morals and ethics in economics from a Protestant perspective. Numerous authoritative sources were considered and used to create a discussion and analysis of how diverse Western worldviews impact on the type of economics which is prescribed and practiced. It was found that different Western worldviews create various standards of understanding and evaluation, which result in varying opinions on what constitutes as morally or ethically acceptable within the discipline of economics.
- Full Text:
- Date Issued: 2017
- Authors: Appalraju, Nerusha
- Date: 2017
- Subjects: Economics -- Moral and ethical aspects , Neoclassical school of economics , Capitalism -- Religious aspects -- Protestant churches , Feminist economics , Economics -- Religious aspects , Environmental economics -- Moral and ethical aspects , Smith, Adam, 1723-1790 , Weber, Max, 1864-1920
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/32480 , vital:24050
- Description: The World Economics Association held an online conference in 2012 where they published many papers on ethics in economics. The topic of ethics in economics became more serious and popular following the 2008 financial crisis. However the case for a professional code of ethics in economics is difficult to introduce and implement due to the multidisciplinary approach of the discipline. Therefore authors such as Dow (2012), De Martino (2012), Freeman (2012) and Earl (2012) urged economists to start thinking about ethics in economics from a pluralistic view. This thesis studied the effects of changing Western worldviews on morals and ethics in economics from a Protestant perspective. Numerous authoritative sources were considered and used to create a discussion and analysis of how diverse Western worldviews impact on the type of economics which is prescribed and practiced. It was found that different Western worldviews create various standards of understanding and evaluation, which result in varying opinions on what constitutes as morally or ethically acceptable within the discipline of economics.
- Full Text:
- Date Issued: 2017
I want to believe there is a girl here under the table
- Authors: Asfour, Fouad-Martin
- Date: 2017
- Subjects: Creative writing (Higher education) South Africa , South African fiction (English) 21st century
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/7190 , vital:21227
- Description: Written in non-linear fragments, my thesis is what Audre Lorde in her novel Zami calls a "biomythography" - the weaving together of myth, history and biography in epic narrative form, a style of composition that represents all the ways in which we perceive the world. Using repetition and shifting memories, I draw from my bicultural upbringing in Offenbach, a city in Germany populated mostly by migrants, as well as my experience of working in art and culture internationally, travelling and living in different countries. Interrogating objects, buildings, family photographs, books and movies, and listening to the silences of the unvoiced, I upset and play with experiences of othering, assumptions and expectations about identity and ask questions about home, belonging and migration, mother tongue and translation. I draw inspiration from Korean American artist Theresa Hak Kyung Cha's use of texts, documents and images to explore dislocation and memory, as well as authors who engage language, translation and belonging such as Mikhail Shishkin, Yoko Tawada, Gloria Anzaldua and Mohammed Khair-Eddine.
- Full Text:
- Date Issued: 2017
- Authors: Asfour, Fouad-Martin
- Date: 2017
- Subjects: Creative writing (Higher education) South Africa , South African fiction (English) 21st century
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/7190 , vital:21227
- Description: Written in non-linear fragments, my thesis is what Audre Lorde in her novel Zami calls a "biomythography" - the weaving together of myth, history and biography in epic narrative form, a style of composition that represents all the ways in which we perceive the world. Using repetition and shifting memories, I draw from my bicultural upbringing in Offenbach, a city in Germany populated mostly by migrants, as well as my experience of working in art and culture internationally, travelling and living in different countries. Interrogating objects, buildings, family photographs, books and movies, and listening to the silences of the unvoiced, I upset and play with experiences of othering, assumptions and expectations about identity and ask questions about home, belonging and migration, mother tongue and translation. I draw inspiration from Korean American artist Theresa Hak Kyung Cha's use of texts, documents and images to explore dislocation and memory, as well as authors who engage language, translation and belonging such as Mikhail Shishkin, Yoko Tawada, Gloria Anzaldua and Mohammed Khair-Eddine.
- Full Text:
- Date Issued: 2017
An intervention on how using easily accessible resources to carry out hands-on practical activities in science influences science teachers’ conceptual development and dispositions
- Authors: Asheela, Eva Ndagwedha
- Date: 2017
- Subjects: Science teachers -- In-service training -- Namibia , Science teachers -- Namibia -- Case studies , Science -- Study and teaching -- Activity programs -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/8330 , vital:21385
- Description: The reform and transformation of education systems in terms of enhancing Science, Technology Engineering and Mathematics (STEM) education in the schooling systems is gaining momentum in different parts of the world. It is argued that there is a need to enhance science education, particularly in Africa, because science education is considered to be the main vehicle through which the greater objectives such as national development and improvement in the quality of life can be realised. Namibia as a country is no exception. A key way through which science education can be enhanced is through carrying out practical activities during teaching and learning. Despite the crucial role that practical activities play in science subjects, it appears that they are not carried out in most of the Namibian science classrooms. It is against this background that this study explored an intervention on how easily accessible resources to carry out hands-on practical activities in science, influenced science teachers’ conceptual development and dispositions towards the use of practical activities in science. In this study, a mixed methods case study approach underpinned by an interpretive paradigm was adopted. The research was conducted with 21 in-service science teachers from schools in Namibia who were all on a two year part-time BEd (Honours) program delivered in Namibia by a South African university from the Eastern Cape. To generate data, document analysis, questionnaires, semi-structured interviews, an intervention in the form of workshops on practical activities, lesson observations, which were videotaped, as well as teacher reflections were used. Conceptual development, disposition and professional development served as the conceptual lenses. Vygotsky’s sociocultural theory in conjunction with Shulman’s pedagogical content knowledge (PCK) were the theoretical frameworks adopted in the study.The findings showed that there was a general perception among the participants before the intervention that in order to carry out practical activities, well-equipped laboratories, conventional chemicals and equipment are needed. Some teachers had never used practical activities in their science classes with a range of constraints or hindrances provided as reasons. The findings additionally showed that for teachers to use easily accessible resources to carry out practical activities in their science classrooms, they need the knowledge and exposure on how to use these resources. The findings thus showed that this professional development approach raised motivation, knowledge and the skills of the science teacher participants to include practical activities in their science lessons using easily accessible resources. A recommendation is that if teachers are given opportunities, through professional development platforms to engage in hands- on practical activities using easily accessible resources, they can be enabled and motivated to implement these in their science classrooms.
- Full Text:
- Date Issued: 2017
- Authors: Asheela, Eva Ndagwedha
- Date: 2017
- Subjects: Science teachers -- In-service training -- Namibia , Science teachers -- Namibia -- Case studies , Science -- Study and teaching -- Activity programs -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/8330 , vital:21385
- Description: The reform and transformation of education systems in terms of enhancing Science, Technology Engineering and Mathematics (STEM) education in the schooling systems is gaining momentum in different parts of the world. It is argued that there is a need to enhance science education, particularly in Africa, because science education is considered to be the main vehicle through which the greater objectives such as national development and improvement in the quality of life can be realised. Namibia as a country is no exception. A key way through which science education can be enhanced is through carrying out practical activities during teaching and learning. Despite the crucial role that practical activities play in science subjects, it appears that they are not carried out in most of the Namibian science classrooms. It is against this background that this study explored an intervention on how easily accessible resources to carry out hands-on practical activities in science, influenced science teachers’ conceptual development and dispositions towards the use of practical activities in science. In this study, a mixed methods case study approach underpinned by an interpretive paradigm was adopted. The research was conducted with 21 in-service science teachers from schools in Namibia who were all on a two year part-time BEd (Honours) program delivered in Namibia by a South African university from the Eastern Cape. To generate data, document analysis, questionnaires, semi-structured interviews, an intervention in the form of workshops on practical activities, lesson observations, which were videotaped, as well as teacher reflections were used. Conceptual development, disposition and professional development served as the conceptual lenses. Vygotsky’s sociocultural theory in conjunction with Shulman’s pedagogical content knowledge (PCK) were the theoretical frameworks adopted in the study.The findings showed that there was a general perception among the participants before the intervention that in order to carry out practical activities, well-equipped laboratories, conventional chemicals and equipment are needed. Some teachers had never used practical activities in their science classes with a range of constraints or hindrances provided as reasons. The findings additionally showed that for teachers to use easily accessible resources to carry out practical activities in their science classrooms, they need the knowledge and exposure on how to use these resources. The findings thus showed that this professional development approach raised motivation, knowledge and the skills of the science teacher participants to include practical activities in their science lessons using easily accessible resources. A recommendation is that if teachers are given opportunities, through professional development platforms to engage in hands- on practical activities using easily accessible resources, they can be enabled and motivated to implement these in their science classrooms.
- Full Text:
- Date Issued: 2017
Data compression, field of interest shaping and fast algorithms for direction-dependent deconvolution in radio interferometry
- Authors: Atemkeng, Marcellin T
- Date: 2017
- Subjects: Radio astronomy , Solar radio emission , Radio interferometers , Signal processing -- Digital techniques , Algorithms , Data compression (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6324 , vital:21089
- Description: In radio interferometry, observed visibilities are intrinsically sampled at some interval in time and frequency. Modern interferometers are capable of producing data at very high time and frequency resolution; practical limits on storage and computation costs require that some form of data compression be imposed. The traditional form of compression is simple averaging of the visibilities over coarser time and frequency bins. This has an undesired side effect: the resulting averaged visibilities “decorrelate”, and do so differently depending on the baseline length and averaging interval. This translates into a non-trivial signature in the image domain known as “smearing”, which manifests itself as an attenuation in amplitude towards off-centre sources. With the increasing fields of view and/or longer baselines employed in modern and future instruments, the trade-off between data rate and smearing becomes increasingly unfavourable. Averaging also results in baseline length and a position-dependent point spread function (PSF). In this work, we investigate alternative approaches to low-loss data compression. We show that averaging of the visibility data can be understood as a form of convolution by a boxcar-like window function, and that by employing alternative baseline-dependent window functions a more optimal interferometer smearing response may be induced. Specifically, we can improve amplitude response over a chosen field of interest and attenuate sources outside the field of interest. The main cost of this technique is a reduction in nominal sensitivity; we investigate the smearing vs. sensitivity trade-off and show that in certain regimes a favourable compromise can be achieved. We show the application of this technique to simulated data from the Jansky Very Large Array and the European Very Long Baseline Interferometry Network. Furthermore, we show that the position-dependent PSF shape induced by averaging can be approximated using linear algebraic properties to effectively reduce the computational complexity for evaluating the PSF at each sky position. We conclude by implementing a position-dependent PSF deconvolution in an imaging and deconvolution framework. Using the Low-Frequency Array radio interferometer, we show that deconvolution with position-dependent PSFs results in higher image fidelity compared to a simple CLEAN algorithm and its derivatives.
- Full Text:
- Date Issued: 2017
- Authors: Atemkeng, Marcellin T
- Date: 2017
- Subjects: Radio astronomy , Solar radio emission , Radio interferometers , Signal processing -- Digital techniques , Algorithms , Data compression (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6324 , vital:21089
- Description: In radio interferometry, observed visibilities are intrinsically sampled at some interval in time and frequency. Modern interferometers are capable of producing data at very high time and frequency resolution; practical limits on storage and computation costs require that some form of data compression be imposed. The traditional form of compression is simple averaging of the visibilities over coarser time and frequency bins. This has an undesired side effect: the resulting averaged visibilities “decorrelate”, and do so differently depending on the baseline length and averaging interval. This translates into a non-trivial signature in the image domain known as “smearing”, which manifests itself as an attenuation in amplitude towards off-centre sources. With the increasing fields of view and/or longer baselines employed in modern and future instruments, the trade-off between data rate and smearing becomes increasingly unfavourable. Averaging also results in baseline length and a position-dependent point spread function (PSF). In this work, we investigate alternative approaches to low-loss data compression. We show that averaging of the visibility data can be understood as a form of convolution by a boxcar-like window function, and that by employing alternative baseline-dependent window functions a more optimal interferometer smearing response may be induced. Specifically, we can improve amplitude response over a chosen field of interest and attenuate sources outside the field of interest. The main cost of this technique is a reduction in nominal sensitivity; we investigate the smearing vs. sensitivity trade-off and show that in certain regimes a favourable compromise can be achieved. We show the application of this technique to simulated data from the Jansky Very Large Array and the European Very Long Baseline Interferometry Network. Furthermore, we show that the position-dependent PSF shape induced by averaging can be approximated using linear algebraic properties to effectively reduce the computational complexity for evaluating the PSF at each sky position. We conclude by implementing a position-dependent PSF deconvolution in an imaging and deconvolution framework. Using the Low-Frequency Array radio interferometer, we show that deconvolution with position-dependent PSFs results in higher image fidelity compared to a simple CLEAN algorithm and its derivatives.
- Full Text:
- Date Issued: 2017
Biogeomorphic aspects of lichen colonisation in part of western Dronning Maud Land, Antarctica
- Authors: Ayres, Gabrielle Alexzena
- Date: 2017
- Subjects: Lichen communities -- Queen Maud Land , Lichens -- Ecology -- Queen Maud Land , Polar regions , Ecology -- Polar regions , Antarctica , Ecology -- Antarctica
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/19713 , vital:22477
- Description: Ice-free regions in Antarctica provide natural laboratories for investigating and modelling change in landscapes and ecosystems. The terrestrial ecosystems in western Dronning Maud Land are potentially critical to improve current understanding of polar ecosystems, however, they remain poorly represented and under-protected. Lichen habitats were used to elucidate geomorphic-biological feedbacks that shape the landscape’s topography and biodiversity, which in turn promote environmental heterogeneity. Environmental parameters acting on two landforms were measured to determine the colonisation and growth of lichens in niche habitats. The habitats were identified and characterised, and topographic heterogeneity was found to control lichen colonisation. Micro-topographical niches provide the most stable environments for colonisation, and are preferred habitats. Lichen-habitat interactions were species specific, and closely related to insolation and moisture availability. The bidirectional relationships between rock weathering and lichen colonisation was ascertained. Results showed that lichens are good indicators of landform heterogeneity, but also promote landform heterogeneity. Given the habitat preferences of specific lichen species, they provide proxy to evaluating environmental responses, especially environmental change. The findings of this research are to be used as baseline data for future studies exploring ecosystem development in emerging landforms.
- Full Text:
- Date Issued: 2017
- Authors: Ayres, Gabrielle Alexzena
- Date: 2017
- Subjects: Lichen communities -- Queen Maud Land , Lichens -- Ecology -- Queen Maud Land , Polar regions , Ecology -- Polar regions , Antarctica , Ecology -- Antarctica
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/19713 , vital:22477
- Description: Ice-free regions in Antarctica provide natural laboratories for investigating and modelling change in landscapes and ecosystems. The terrestrial ecosystems in western Dronning Maud Land are potentially critical to improve current understanding of polar ecosystems, however, they remain poorly represented and under-protected. Lichen habitats were used to elucidate geomorphic-biological feedbacks that shape the landscape’s topography and biodiversity, which in turn promote environmental heterogeneity. Environmental parameters acting on two landforms were measured to determine the colonisation and growth of lichens in niche habitats. The habitats were identified and characterised, and topographic heterogeneity was found to control lichen colonisation. Micro-topographical niches provide the most stable environments for colonisation, and are preferred habitats. Lichen-habitat interactions were species specific, and closely related to insolation and moisture availability. The bidirectional relationships between rock weathering and lichen colonisation was ascertained. Results showed that lichens are good indicators of landform heterogeneity, but also promote landform heterogeneity. Given the habitat preferences of specific lichen species, they provide proxy to evaluating environmental responses, especially environmental change. The findings of this research are to be used as baseline data for future studies exploring ecosystem development in emerging landforms.
- Full Text:
- Date Issued: 2017
Visual narratives of division in contemporary Palestinian art and social space
- Authors: Baasch, Rachel Mary
- Date: 2017
- Subjects: Art, Palestinian Arab , Art, Palestinian Arab -- Political aspects , Art and society -- Palestine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41770 , vital:25132
- Description: This study analyses artworks by contemporary Palestinian artists that respond to visual narratives of division in social space from a perspective grounded in a South African context. The state of Israel is built on Historic Palestine. Political Zionism has created an ideological narrative of division that positions people of the Jewish faith as the rightful heirs to the land on which Palestinians have lived for centuries. In order to execute their vision of an exclusively Jewish nation state, the founding pioneers of political Zionism colonised and ethnically cleansed Historic Palestine, establishing Israel in 1948. To sustain the exclusive claim to Palestinian land, Israel has divided the space and the people in it at every possible level. The greatest testament to these efforts is the Israeli apartheid wall and checkpoint security system that can be described as a monumental visual narrative of division. With each second that passes, Israel claims more Palestinian land and expands on existing fences, walls and barriers. It is no secret that the Occupied Palestinian Territories are rapidly transforming into open-air prisons. Israel has stolen the Palestinian horizon line and replaced it with a concrete wall that blocks out light, vision and optimism. Within the shadows of these conflicted, traumatised sites of division, Palestinian artists seek openings, cracks and loopholes that signal the possibility for physical and psychological transgression of these seemingly impenetrable structures of division. I have developed a creative methodology that can be understood through the metaphor of ‘looking with the skin’ as a way to identify and analyse visual narratives of division and artistic responses to sites of division in Palestinian social space. Looking with the skin combines aspects of participant observation (specifically the emphasis on engaged fieldwork) from the discipline of Anthropology with the method of visual analysis from the discipline of Art History. In my application of this method through primary fieldwork conducted within the Occupied Palestinian West Bank Territory from 2013 and 2014, I have learnt that Israel’s colonisation, military occupation and system of apartheid directly impacts the ability of Palestinian artists to make and disseminate their work as well as the choice of content within their artwork. The artworks analysed in this thesis by the artists Khaled Jarrar, Y ael Bartana, Larissa Sansour, Hasan Darahgmeh, Fareh Saleh and Emily Jacir can be positioned in relation to artworks by artists based within a South African context, namely Thando Mama, Serge Alain Nitegeka and Doung Anwar Jahangeer. In this thesis I present a combination of my own photographic documentation of sites of division with the West Bank OPT in relation to the specific artworks made by the artists mentioned above. In my analysis of the photographic documentation and the artists’ work I highlight similarities, parallels, threads and intersecting narratives that connect different artists to one another and to the sites of division they are responding to within their artistic practice. This study carves a small conceptual pathway through ideological and physical walls from South Africa to Palestine through the study of contemporary art and visual culture.
- Full Text:
- Date Issued: 2017
- Authors: Baasch, Rachel Mary
- Date: 2017
- Subjects: Art, Palestinian Arab , Art, Palestinian Arab -- Political aspects , Art and society -- Palestine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41770 , vital:25132
- Description: This study analyses artworks by contemporary Palestinian artists that respond to visual narratives of division in social space from a perspective grounded in a South African context. The state of Israel is built on Historic Palestine. Political Zionism has created an ideological narrative of division that positions people of the Jewish faith as the rightful heirs to the land on which Palestinians have lived for centuries. In order to execute their vision of an exclusively Jewish nation state, the founding pioneers of political Zionism colonised and ethnically cleansed Historic Palestine, establishing Israel in 1948. To sustain the exclusive claim to Palestinian land, Israel has divided the space and the people in it at every possible level. The greatest testament to these efforts is the Israeli apartheid wall and checkpoint security system that can be described as a monumental visual narrative of division. With each second that passes, Israel claims more Palestinian land and expands on existing fences, walls and barriers. It is no secret that the Occupied Palestinian Territories are rapidly transforming into open-air prisons. Israel has stolen the Palestinian horizon line and replaced it with a concrete wall that blocks out light, vision and optimism. Within the shadows of these conflicted, traumatised sites of division, Palestinian artists seek openings, cracks and loopholes that signal the possibility for physical and psychological transgression of these seemingly impenetrable structures of division. I have developed a creative methodology that can be understood through the metaphor of ‘looking with the skin’ as a way to identify and analyse visual narratives of division and artistic responses to sites of division in Palestinian social space. Looking with the skin combines aspects of participant observation (specifically the emphasis on engaged fieldwork) from the discipline of Anthropology with the method of visual analysis from the discipline of Art History. In my application of this method through primary fieldwork conducted within the Occupied Palestinian West Bank Territory from 2013 and 2014, I have learnt that Israel’s colonisation, military occupation and system of apartheid directly impacts the ability of Palestinian artists to make and disseminate their work as well as the choice of content within their artwork. The artworks analysed in this thesis by the artists Khaled Jarrar, Y ael Bartana, Larissa Sansour, Hasan Darahgmeh, Fareh Saleh and Emily Jacir can be positioned in relation to artworks by artists based within a South African context, namely Thando Mama, Serge Alain Nitegeka and Doung Anwar Jahangeer. In this thesis I present a combination of my own photographic documentation of sites of division with the West Bank OPT in relation to the specific artworks made by the artists mentioned above. In my analysis of the photographic documentation and the artists’ work I highlight similarities, parallels, threads and intersecting narratives that connect different artists to one another and to the sites of division they are responding to within their artistic practice. This study carves a small conceptual pathway through ideological and physical walls from South Africa to Palestine through the study of contemporary art and visual culture.
- Full Text:
- Date Issued: 2017
The role of protected areas in the conservation and management of fisheries in the Chobe District of Botswana
- Authors: Bakane, Modiegi
- Date: 2017
- Subjects: Cichlids Botswana Chobe District , Protected areas Botswana Chobe District , Fishery management Botswana Chobe District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7459 , vital:21262
- Description: This study was aimed at better understanding the function of protected areas as a management strategy for the Chobe District fishery in Botswana, by first investigating the relative abundance in fish communities in and outside protected areas and secondly, by performing an assessment of the biology of commercially important large cichlid species viz threespot tilapia Oreochromis andersonii, greenhead tilapia Oreochromis macrochir and redbreast tilapia Coptodon rendalli. In this study, data and specimens were collected during seasonal surveys between September 2014 and April 2015, using the standard graded fleets of gillnets employed in other programmes in the region, together with D-nets, angling and electro-fishing. The study demonstrated that fish communities in the floodplain ecosystems in the Chobe District of Botswana were representative of the region, containing some 70 species in 14 families. This study also demonstrated that for all the species collected, the mean Catch Per Unit Effort (CPUE) by weight for all the species was significantly higher in protected areas (Kruskal Wallis Test; P<0.05) namely, Zibadianja Lagoon (38 ± 31 kg/net.night"1 and Savuti River/marsh 25 ± 19 kg/net.night"1) than in the fished Chobe River floodplains CPUE (6 ± 3 kg/net.night-1). Biological contributions were estimates of longevity, growth and maturity for O. andersonii, O. macrochir and C. rendalli. Age and growth were estimated using sectioned sagittal otoliths. The Von Bertalanffy growth equation from otolith derived length at age was Lt(mm) =298 (1-e-0 59(t=- 098)) for O. andersonii and Lt(mm) = 337 (1-e-0'20(t=-235)) for C. rendalli. The results indicated that protected areas enhanced fish longevity, and fish in protected areas were larger and older than those in exploited areas. Maturity estimates for the large cichlids were consistent with other research in the region and the length-at-50% maturity was estimated as 250mm Lt for O. andersonii, 225 mm Lt for O. macrochir and 210 mm Lt for C. rendalli. Management recommendations are therefore to retain gill net mesh size regulations that ensure that these fish reach maturity and can breed before being harvested and to assess the possibility of increasing the number of protected areas in the district.
- Full Text:
- Date Issued: 2017
- Authors: Bakane, Modiegi
- Date: 2017
- Subjects: Cichlids Botswana Chobe District , Protected areas Botswana Chobe District , Fishery management Botswana Chobe District
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/7459 , vital:21262
- Description: This study was aimed at better understanding the function of protected areas as a management strategy for the Chobe District fishery in Botswana, by first investigating the relative abundance in fish communities in and outside protected areas and secondly, by performing an assessment of the biology of commercially important large cichlid species viz threespot tilapia Oreochromis andersonii, greenhead tilapia Oreochromis macrochir and redbreast tilapia Coptodon rendalli. In this study, data and specimens were collected during seasonal surveys between September 2014 and April 2015, using the standard graded fleets of gillnets employed in other programmes in the region, together with D-nets, angling and electro-fishing. The study demonstrated that fish communities in the floodplain ecosystems in the Chobe District of Botswana were representative of the region, containing some 70 species in 14 families. This study also demonstrated that for all the species collected, the mean Catch Per Unit Effort (CPUE) by weight for all the species was significantly higher in protected areas (Kruskal Wallis Test; P<0.05) namely, Zibadianja Lagoon (38 ± 31 kg/net.night"1 and Savuti River/marsh 25 ± 19 kg/net.night"1) than in the fished Chobe River floodplains CPUE (6 ± 3 kg/net.night-1). Biological contributions were estimates of longevity, growth and maturity for O. andersonii, O. macrochir and C. rendalli. Age and growth were estimated using sectioned sagittal otoliths. The Von Bertalanffy growth equation from otolith derived length at age was Lt(mm) =298 (1-e-0 59(t=- 098)) for O. andersonii and Lt(mm) = 337 (1-e-0'20(t=-235)) for C. rendalli. The results indicated that protected areas enhanced fish longevity, and fish in protected areas were larger and older than those in exploited areas. Maturity estimates for the large cichlids were consistent with other research in the region and the length-at-50% maturity was estimated as 250mm Lt for O. andersonii, 225 mm Lt for O. macrochir and 210 mm Lt for C. rendalli. Management recommendations are therefore to retain gill net mesh size regulations that ensure that these fish reach maturity and can breed before being harvested and to assess the possibility of increasing the number of protected areas in the district.
- Full Text:
- Date Issued: 2017
Exploring transformative social learning and sustainability in community based irrigation scheme contexts in Mozambique
- Authors: Baloi, Aristides
- Date: 2017
- Subjects: Social learning -- Mozambique , Irrigation -- Social aspects -- Mozambique , Water resources development -- Mozambique , Sustainable agriculture -- Mozambique , Community development -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50154 , vital:25963
- Description: This study set out to examine transformative social learning and sustainability in the context of community-based irrigation systems in Mozambique. These irrigation systems are socio-ecological in nature. The history of irrigation systems in Mozambique can be described in two periods: pre-Independence period (mainly the colonial period) and the post-Independence period from 1975 onwards. Most recently, the Mozambique Government has introduced a policy which supports community-based irrigation system implementation and management via irrigation associations in a move to support a shift from rain-fed farming practices to irrigation-supported farming practices amongst smallholder farmers. It is this shift in the object of activity that this study focusses on. It does this by studying learning process in the constituted irrigation associations, examining whether such learning is transformative and sustainability oriented or not, and how such learning can be further expanded and supported. Learning may occur in socio-ecological systems, but whether that learning enables transformation and sustainability of irrigation systems and the constituted associations is as yet under-explored in the Mozambique context and in the context of Education for Sustainable Development in southern Africa. The aim of this research was therefore to understand transformative social learning within the development of sustainable irrigation practices in the context of irrigation associations and new agrarian policy development in Mozambique. To examine transformative social learning in sustainable irrigation system practices (including management practices), the study worked with three research goals, which also formed phases of the study’s design: GOAL 1: Examine how and what transformative social learning has (or has not) emerged in existing activity systems to date (Phase 1: Activity System Analysis). GOAL 2: Examine how transformative social learning could emerge through expansive learning processes (Phase 2: Identification of contradictions and new solution modelling through Developmental Work Research and Change Laboratories). GOAL 3: Identify what opportunities exist for ongoing transformative social learning (Phase 3: Identification of absences and ongoing dialectical transformation possibilities). The study draws on theories of Social Learning, Transformative Learning and Cultural Historical Activity Theory’s (CHAT) expansive learning and formative interventionist research framework to develop insights into the learning processes. It works especially with third generation Cultural Historical Activity Theory which provides a theory of expansive social learning and collective transformative agency formation, which I deemed most appropriate for the need to understand the transformation of farmers’ activities in a collective formation such as an irrigation association. The study involved identification and examination of interacting activity systems, contradictions or dissonances in two case studies of community-based irrigation system development via the respective associations. It involved identifying existing learning, as well as engaging in formative intervention research to expand learning in two case study sites: namely the Macubulane and Massaca Irrigation Associations, located near Maputo, Mozambique in the Inkomati and Umbeluzi river basins. The Macubulane community practices a monocropping system of sugar cane plantations using sprinkler irrigation methods and the Massaca community practices a mixed cropping system growing vegetables using mainly gravity or furrow irrigation methods. The study uses a qualitative research approach and is underlaboured by Dialectical Critical Realism which allowed for a deeper probing of ontology and transformative praxis, and transformative learning. The study used methods which included in-depth interviews, change laboratory workshops, document analysis and focus group interviews with farmers and subjects in associated activity systems. Analysis involved activity system analysis, identification of contradictions, modeling of solutions, transformative agency analysis, as well as analysis of real and nominal absences and generative mechanisms as recommended in dialectical critical realism. I used inductive, abductive and retroductive modes of inference, relying on the latter to identify further potential for transformative learning. The study demonstrates that within the associations, transformative social learning is taking place as farmers seek to address problems and contradictions. This learning leads to the creation of new agency and capabilities by ensuring good yields and continuous improvement of management practices and social status. Learning operates through formal mediation in the irrigation system of workplace-based operation, maintenance and crop management practices (i.e. through workplace learning). Social learning occurs through collective engagement with the constraints that the association faces while applying new knowledge, introducing new technology, in the process of administration and planning of irrigation activities. Expansive learning is possible when mediated actively through formative interventions in change laboratory workshops. All three types of learning were found to be present and possible in the context of the two irrigation scheme contexts. The main study findings are that transformative social learning is a collective object-driven process in the context of a transforming object (from rain-fed to sustainable community-based irrigation scheme farming in this study), that can be explained from the level of generative mechanisms and associated real absences that shape nominal absences and contradictions within and between activity systems. These induce, and have potential to induce, transformative learning in irrigation systems, including the emergence of transformative agency via learning through workplace-based, wider social learning, and expansive learning interaction processes amongst subjects in interacting activity systems. Absenting absences is also crucial for extending the potential of transformative learning in irrigation associations. The study further shows how critical realism helps to interpret learning processes and how it strengthens the empirical findings obtained from qualitative analysis. A key outcome of the study is a model that frames conceptualisation of transformative social learning in irrigation systems. The model and the insights gained into farmers learning around the transformation of the object of activity explored in this study have implications for wider curriculum and policy development interventions. The study therefore also makes recommendations for curriculum development and policy implementation intervention. The curriculum development recommendations are not at the level of making recommendations for new courses only, but frame how the design of new courses should take into account the wider processes of learning and change associated with the transformation of an object of activity as articulated in the study. It recommends an approach that allows for in-field engagement with contradictions and the absenting of absences (a problem-based type of curriculum) that will also allow for conceptual development and understanding of the changing object of activity (i.e. community-based irrigation scheme practice and management). The main policy recommendation made from the study is to invest more in farmer support and farmers’ learning so that they can transition from rain-fed agriculture to sustainable irrigation scheme development and management via their associations. The research contributes to knowledge production on irrigation practices; considering that substantial understandings were generated through analysis of communal irrigation scheme practice and management and its implications, especially from a transformative learning perspective. As shown in this study, transformative social learning theories are still not well understood in the context of irrigation system development, and this study has contributed knowledge to this field. The study contributes towards understanding of sustainability learning in irrigation associations in terms of concepts and practices. The study offers a model for transformative social learning in irrigation scheme development and suggests an expanded curriculum for community-based irrigation association practice and management. Overall, the study contributes to an understanding of transformative, sustainability oriented learning processes as support for the emergence of community-based irrigation associations. Additionally, the study has added perspectives on how to frame transformative social learning from a CHAT and critical realist perspective in Education for Sustainable Development. The study also contributes to a growing body of scholarship in southern Africa which seeks to develop expansive, transformative social learning approaches in response to concerns experienced by communities who are reliant on natural resources and the environment for their livelihoods and well-being, and who are also seeking to emerge out of poverty.
- Full Text:
- Date Issued: 2017
- Authors: Baloi, Aristides
- Date: 2017
- Subjects: Social learning -- Mozambique , Irrigation -- Social aspects -- Mozambique , Water resources development -- Mozambique , Sustainable agriculture -- Mozambique , Community development -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50154 , vital:25963
- Description: This study set out to examine transformative social learning and sustainability in the context of community-based irrigation systems in Mozambique. These irrigation systems are socio-ecological in nature. The history of irrigation systems in Mozambique can be described in two periods: pre-Independence period (mainly the colonial period) and the post-Independence period from 1975 onwards. Most recently, the Mozambique Government has introduced a policy which supports community-based irrigation system implementation and management via irrigation associations in a move to support a shift from rain-fed farming practices to irrigation-supported farming practices amongst smallholder farmers. It is this shift in the object of activity that this study focusses on. It does this by studying learning process in the constituted irrigation associations, examining whether such learning is transformative and sustainability oriented or not, and how such learning can be further expanded and supported. Learning may occur in socio-ecological systems, but whether that learning enables transformation and sustainability of irrigation systems and the constituted associations is as yet under-explored in the Mozambique context and in the context of Education for Sustainable Development in southern Africa. The aim of this research was therefore to understand transformative social learning within the development of sustainable irrigation practices in the context of irrigation associations and new agrarian policy development in Mozambique. To examine transformative social learning in sustainable irrigation system practices (including management practices), the study worked with three research goals, which also formed phases of the study’s design: GOAL 1: Examine how and what transformative social learning has (or has not) emerged in existing activity systems to date (Phase 1: Activity System Analysis). GOAL 2: Examine how transformative social learning could emerge through expansive learning processes (Phase 2: Identification of contradictions and new solution modelling through Developmental Work Research and Change Laboratories). GOAL 3: Identify what opportunities exist for ongoing transformative social learning (Phase 3: Identification of absences and ongoing dialectical transformation possibilities). The study draws on theories of Social Learning, Transformative Learning and Cultural Historical Activity Theory’s (CHAT) expansive learning and formative interventionist research framework to develop insights into the learning processes. It works especially with third generation Cultural Historical Activity Theory which provides a theory of expansive social learning and collective transformative agency formation, which I deemed most appropriate for the need to understand the transformation of farmers’ activities in a collective formation such as an irrigation association. The study involved identification and examination of interacting activity systems, contradictions or dissonances in two case studies of community-based irrigation system development via the respective associations. It involved identifying existing learning, as well as engaging in formative intervention research to expand learning in two case study sites: namely the Macubulane and Massaca Irrigation Associations, located near Maputo, Mozambique in the Inkomati and Umbeluzi river basins. The Macubulane community practices a monocropping system of sugar cane plantations using sprinkler irrigation methods and the Massaca community practices a mixed cropping system growing vegetables using mainly gravity or furrow irrigation methods. The study uses a qualitative research approach and is underlaboured by Dialectical Critical Realism which allowed for a deeper probing of ontology and transformative praxis, and transformative learning. The study used methods which included in-depth interviews, change laboratory workshops, document analysis and focus group interviews with farmers and subjects in associated activity systems. Analysis involved activity system analysis, identification of contradictions, modeling of solutions, transformative agency analysis, as well as analysis of real and nominal absences and generative mechanisms as recommended in dialectical critical realism. I used inductive, abductive and retroductive modes of inference, relying on the latter to identify further potential for transformative learning. The study demonstrates that within the associations, transformative social learning is taking place as farmers seek to address problems and contradictions. This learning leads to the creation of new agency and capabilities by ensuring good yields and continuous improvement of management practices and social status. Learning operates through formal mediation in the irrigation system of workplace-based operation, maintenance and crop management practices (i.e. through workplace learning). Social learning occurs through collective engagement with the constraints that the association faces while applying new knowledge, introducing new technology, in the process of administration and planning of irrigation activities. Expansive learning is possible when mediated actively through formative interventions in change laboratory workshops. All three types of learning were found to be present and possible in the context of the two irrigation scheme contexts. The main study findings are that transformative social learning is a collective object-driven process in the context of a transforming object (from rain-fed to sustainable community-based irrigation scheme farming in this study), that can be explained from the level of generative mechanisms and associated real absences that shape nominal absences and contradictions within and between activity systems. These induce, and have potential to induce, transformative learning in irrigation systems, including the emergence of transformative agency via learning through workplace-based, wider social learning, and expansive learning interaction processes amongst subjects in interacting activity systems. Absenting absences is also crucial for extending the potential of transformative learning in irrigation associations. The study further shows how critical realism helps to interpret learning processes and how it strengthens the empirical findings obtained from qualitative analysis. A key outcome of the study is a model that frames conceptualisation of transformative social learning in irrigation systems. The model and the insights gained into farmers learning around the transformation of the object of activity explored in this study have implications for wider curriculum and policy development interventions. The study therefore also makes recommendations for curriculum development and policy implementation intervention. The curriculum development recommendations are not at the level of making recommendations for new courses only, but frame how the design of new courses should take into account the wider processes of learning and change associated with the transformation of an object of activity as articulated in the study. It recommends an approach that allows for in-field engagement with contradictions and the absenting of absences (a problem-based type of curriculum) that will also allow for conceptual development and understanding of the changing object of activity (i.e. community-based irrigation scheme practice and management). The main policy recommendation made from the study is to invest more in farmer support and farmers’ learning so that they can transition from rain-fed agriculture to sustainable irrigation scheme development and management via their associations. The research contributes to knowledge production on irrigation practices; considering that substantial understandings were generated through analysis of communal irrigation scheme practice and management and its implications, especially from a transformative learning perspective. As shown in this study, transformative social learning theories are still not well understood in the context of irrigation system development, and this study has contributed knowledge to this field. The study contributes towards understanding of sustainability learning in irrigation associations in terms of concepts and practices. The study offers a model for transformative social learning in irrigation scheme development and suggests an expanded curriculum for community-based irrigation association practice and management. Overall, the study contributes to an understanding of transformative, sustainability oriented learning processes as support for the emergence of community-based irrigation associations. Additionally, the study has added perspectives on how to frame transformative social learning from a CHAT and critical realist perspective in Education for Sustainable Development. The study also contributes to a growing body of scholarship in southern Africa which seeks to develop expansive, transformative social learning approaches in response to concerns experienced by communities who are reliant on natural resources and the environment for their livelihoods and well-being, and who are also seeking to emerge out of poverty.
- Full Text:
- Date Issued: 2017
Exploring attitudes and perceptions about the knowledge acquisition process and experiences of Ngangelizwe youth graduates in the Eastern Cape to understand the significance of their education: a Freirean approach
- Authors: Bango, Yanda Tamsanqeleka
- Date: 2017
- Subjects: Freire, Paulo, 1921-1997 , Education -- Sociological aspects -- South Africa -- Mthatha , College graduates, Black -- South Africa -- Mthatha -- Attitudes , College graduates, Black -- South Africa -- Mthatha -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/4277 , vital:20642
- Description: Education is a critical phenomenon which cannot be ignored as its effects cut across all spheres of life, especially the social and economic aspects. In the particular case of South Africa, education has been a serious issue of concern for a very long time and after the transition process took place in 1994 it became a priority on all agendas of governance. Expanding on the already existing debate about education in South Africa, this thesis specifically explores attitudes and perceptions about the knowledge acquisition process and experiences of Ngangelizwe youth graduates to understand the significance of education in their lives. As Freire wrote about the phenomenon of education from the point of view of the oppressed and marginalized in society, his theory explains and aids as a tool for careful analysis in this case. Moreover, considering that at the centre of Freire’s world view was the belief that humans have an ontological vocation to become more fully human, the youth graduates of Ngangelizwe became a good case as they live under conditions that one would regard as dehumanizing and oppressive. The youth graduates’ actions and attitudes would therefore guide and provide indication as to whether their education, both from academic spaces and the community, has empowered them to challenge the dehumanizing and oppressive nature of the dominant culture as a means to becoming fully human in their life and time, particularly in their community of Ngangelizwe. While the general finding has been that the participants’ education portrays both elements of banking and problem-posing education, it was also discovered that it all depends on the level and forces of education that the participants receive their inspiration from. This is due to the fact that education is not one dimensional, it begins from the moment one is born up until he or she no longer exists on earth. Therefore, education does not belong to one group of people; everyone has the ability to educate in as much as he or she has the ability to be educated.
- Full Text:
- Date Issued: 2017
- Authors: Bango, Yanda Tamsanqeleka
- Date: 2017
- Subjects: Freire, Paulo, 1921-1997 , Education -- Sociological aspects -- South Africa -- Mthatha , College graduates, Black -- South Africa -- Mthatha -- Attitudes , College graduates, Black -- South Africa -- Mthatha -- Case studies
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/4277 , vital:20642
- Description: Education is a critical phenomenon which cannot be ignored as its effects cut across all spheres of life, especially the social and economic aspects. In the particular case of South Africa, education has been a serious issue of concern for a very long time and after the transition process took place in 1994 it became a priority on all agendas of governance. Expanding on the already existing debate about education in South Africa, this thesis specifically explores attitudes and perceptions about the knowledge acquisition process and experiences of Ngangelizwe youth graduates to understand the significance of education in their lives. As Freire wrote about the phenomenon of education from the point of view of the oppressed and marginalized in society, his theory explains and aids as a tool for careful analysis in this case. Moreover, considering that at the centre of Freire’s world view was the belief that humans have an ontological vocation to become more fully human, the youth graduates of Ngangelizwe became a good case as they live under conditions that one would regard as dehumanizing and oppressive. The youth graduates’ actions and attitudes would therefore guide and provide indication as to whether their education, both from academic spaces and the community, has empowered them to challenge the dehumanizing and oppressive nature of the dominant culture as a means to becoming fully human in their life and time, particularly in their community of Ngangelizwe. While the general finding has been that the participants’ education portrays both elements of banking and problem-posing education, it was also discovered that it all depends on the level and forces of education that the participants receive their inspiration from. This is due to the fact that education is not one dimensional, it begins from the moment one is born up until he or she no longer exists on earth. Therefore, education does not belong to one group of people; everyone has the ability to educate in as much as he or she has the ability to be educated.
- Full Text:
- Date Issued: 2017
Nonlinear optical responses of phthalocyanines in the presence of nanomaterials or when embedded in polymeric materials
- Authors: Bankole, Owolabi Mutolib
- Date: 2017
- Subjects: Phthalocyanines , Phthalocyanines -- Optical properties , Alkynes , Triazoles , Nonlinear optics , Photochemistry , Complex compounds , Amines , Mercaptopyridine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/45794 , vital:25548
- Description: This work describes the synthesis, photophysical and nonlinear optical characterizations of alkynyl Pcs (1, 2, 3, 8 and 9), 1,2,3-triazole ZnPc (4), mercaptopyridine Pcs (5, 6 and 7) and amino Pcs (10 and 11). Complexes 1, 2, 4, 7, 8, 9 and 11 were newly synthesized and characterized using techniques including 1H-NMR, MALDI-TOF, UV-visible spectrophotometry, FTIR and elemental analysis. The results of the characterizations were in good agreement with their molecular structures, and confirmed the purity of the new molecules. Complex 10 was covalently linked to pristine graphene (GQDs), nitrogen- doped (NGQDs), and sulfur-nitrogen co-doped (SNGQDs) graphene quantum dots; gold nanoparticles (AuNPs); poly(acrylic acid) (PAA); Fe3O4@Ag core-shell and Fe3O4- Ag hybrid nanoparticles via covalent bonding. Complex 11 was linked to Agx Auy alloy nanoparticles via NH2-Au and/or Au-S bonding, 2 and 3 were linked to gold nanoparticles (AuNPs) via clicked reactions. Evidence of successful conjugation of 2, 3, 10 and 11 to nanomaterials was revealed within the UV-vis, EDS, TEM, XRD and XPS spectra. Optical limiting (OL) responses of the samples were evaluated using open aperture Z-scan technique at 532 nm and 10 ns radiation in solution or when embedded in polymer mixtures. The analyses of the Z-scan data for the studied samples did fit to a two-photon absorption mechanism (2PA), but the Pcs and Pc-nanomaterial or polymer composites also possess the multi-photon absorption mechanisms aided by the triplet-triplet population to have reverse saturable absorption (RSA) occur. Phthalocyanines doped in polymer matrices showed larger nonlinear absorption coefficients (ßeff), third-order susceptibility (Im [x(3)]) and second-order hyperpolarizability (y), with an accompanying low intensity threshold (Ium) than in solution. Aggregation in DMSO negatively affected NLO behaviour of Pcs (8 as a case study) at low laser power, and improved at relatively higher laser power. Heavy atom-substituted Pcs (6) enhanced NLO and OL properties than lighter atoms such as 5 and 7. Direct relationship between enhanced photophysical properties and nonlinear effects favoured by excited triplet absorption of the 2, 3, 10 and 11 in presence of nanomaterials was established. Major factor responsible for the enhanced nonlinearities of 10 in the presence of NGQDs and SNGQDs were fully described and attributed to the surface defects caused by the presence of heteroatoms such as nitrogen and sulfur. The studies showed that phthalocyanines-nanomaterial composites were useful in applications such as optical switching, pulse compressor and laser pulse narrowing.
- Full Text:
- Date Issued: 2017
- Authors: Bankole, Owolabi Mutolib
- Date: 2017
- Subjects: Phthalocyanines , Phthalocyanines -- Optical properties , Alkynes , Triazoles , Nonlinear optics , Photochemistry , Complex compounds , Amines , Mercaptopyridine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/45794 , vital:25548
- Description: This work describes the synthesis, photophysical and nonlinear optical characterizations of alkynyl Pcs (1, 2, 3, 8 and 9), 1,2,3-triazole ZnPc (4), mercaptopyridine Pcs (5, 6 and 7) and amino Pcs (10 and 11). Complexes 1, 2, 4, 7, 8, 9 and 11 were newly synthesized and characterized using techniques including 1H-NMR, MALDI-TOF, UV-visible spectrophotometry, FTIR and elemental analysis. The results of the characterizations were in good agreement with their molecular structures, and confirmed the purity of the new molecules. Complex 10 was covalently linked to pristine graphene (GQDs), nitrogen- doped (NGQDs), and sulfur-nitrogen co-doped (SNGQDs) graphene quantum dots; gold nanoparticles (AuNPs); poly(acrylic acid) (PAA); Fe3O4@Ag core-shell and Fe3O4- Ag hybrid nanoparticles via covalent bonding. Complex 11 was linked to Agx Auy alloy nanoparticles via NH2-Au and/or Au-S bonding, 2 and 3 were linked to gold nanoparticles (AuNPs) via clicked reactions. Evidence of successful conjugation of 2, 3, 10 and 11 to nanomaterials was revealed within the UV-vis, EDS, TEM, XRD and XPS spectra. Optical limiting (OL) responses of the samples were evaluated using open aperture Z-scan technique at 532 nm and 10 ns radiation in solution or when embedded in polymer mixtures. The analyses of the Z-scan data for the studied samples did fit to a two-photon absorption mechanism (2PA), but the Pcs and Pc-nanomaterial or polymer composites also possess the multi-photon absorption mechanisms aided by the triplet-triplet population to have reverse saturable absorption (RSA) occur. Phthalocyanines doped in polymer matrices showed larger nonlinear absorption coefficients (ßeff), third-order susceptibility (Im [x(3)]) and second-order hyperpolarizability (y), with an accompanying low intensity threshold (Ium) than in solution. Aggregation in DMSO negatively affected NLO behaviour of Pcs (8 as a case study) at low laser power, and improved at relatively higher laser power. Heavy atom-substituted Pcs (6) enhanced NLO and OL properties than lighter atoms such as 5 and 7. Direct relationship between enhanced photophysical properties and nonlinear effects favoured by excited triplet absorption of the 2, 3, 10 and 11 in presence of nanomaterials was established. Major factor responsible for the enhanced nonlinearities of 10 in the presence of NGQDs and SNGQDs were fully described and attributed to the surface defects caused by the presence of heteroatoms such as nitrogen and sulfur. The studies showed that phthalocyanines-nanomaterial composites were useful in applications such as optical switching, pulse compressor and laser pulse narrowing.
- Full Text:
- Date Issued: 2017
Ecosystem engineering by the wetland plant palmiet: does it control fluvial form and promote diffuse flow in steep-sided valleys of the Cape Fold Mountains
- Authors: Barclay, Amy
- Date: 2017
- Subjects: Prionium serratum , Wetlands -- South Africa -- Eastern Cape , Aquatic plants -- South Africa -- Eastern Cape , Peatland ecology -- South Africa -- Eastern Cape , Kromme River (Eastern Cape, South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4646 , vital:20708
- Description: Ecosystem engineering refers to the way that organisms control the structure and function of ecosystems. It has been suggested that palmiet (Prionium serratum, Thurniaceae) works as an ecosystem engineer, shaping peat wetlands in South Africa. However, there is currently a paucity of evidence supporting this claim. Palmiet has a dense root, rhizome and stem system that forms dense stands, growing from channel banks into fast flowing river channels. This slows river flows, traps sediment, which builds up riverbeds and ultimately blocks river channels, turning the river into a wetland. The aim of this study was to determine if palmiet is an ecosystem engineer and to document its pattern of colonisation and the nature of its control of a fluvial system. This was achieved by undertaking vegetation surveys in the Kromrivier Wetland in the Eastern Cape. The data was analyzed using vegetation classification and ordination, where vegetation communities were linked to environmental factors. It was found that palmiet occupied three distinctive habitats; 1) on near-horizontal valley- bottom habitats filled with sediments that are a mixture of autochthonous organic sediment and allochthonous clastic fines, 2) the bed of gullies that have recently filled with coarse grained clastic sediment, and 3) open water bodies. Three conceptual models were developed, one that accounts for the process of gully bed colonisation, sediment trapping and gully filling, another involving rapid colonisation of sedimentary fill from tributary sediment sources that block a gully, and the third involving colonisation of open-water areas that form in former gullies upstream of the blockage. The study suggests that the wetland has been characterised by repeated cutting and filling cycles, despite which, palmiet has repeatedly reinstated diffuse flow conditions across the valley floor. Palmiet was indicated to exert a key control on fluvial form and dynamics of the wetlands in the Kromrivier valley.
- Full Text:
- Date Issued: 2017
- Authors: Barclay, Amy
- Date: 2017
- Subjects: Prionium serratum , Wetlands -- South Africa -- Eastern Cape , Aquatic plants -- South Africa -- Eastern Cape , Peatland ecology -- South Africa -- Eastern Cape , Kromme River (Eastern Cape, South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4646 , vital:20708
- Description: Ecosystem engineering refers to the way that organisms control the structure and function of ecosystems. It has been suggested that palmiet (Prionium serratum, Thurniaceae) works as an ecosystem engineer, shaping peat wetlands in South Africa. However, there is currently a paucity of evidence supporting this claim. Palmiet has a dense root, rhizome and stem system that forms dense stands, growing from channel banks into fast flowing river channels. This slows river flows, traps sediment, which builds up riverbeds and ultimately blocks river channels, turning the river into a wetland. The aim of this study was to determine if palmiet is an ecosystem engineer and to document its pattern of colonisation and the nature of its control of a fluvial system. This was achieved by undertaking vegetation surveys in the Kromrivier Wetland in the Eastern Cape. The data was analyzed using vegetation classification and ordination, where vegetation communities were linked to environmental factors. It was found that palmiet occupied three distinctive habitats; 1) on near-horizontal valley- bottom habitats filled with sediments that are a mixture of autochthonous organic sediment and allochthonous clastic fines, 2) the bed of gullies that have recently filled with coarse grained clastic sediment, and 3) open water bodies. Three conceptual models were developed, one that accounts for the process of gully bed colonisation, sediment trapping and gully filling, another involving rapid colonisation of sedimentary fill from tributary sediment sources that block a gully, and the third involving colonisation of open-water areas that form in former gullies upstream of the blockage. The study suggests that the wetland has been characterised by repeated cutting and filling cycles, despite which, palmiet has repeatedly reinstated diffuse flow conditions across the valley floor. Palmiet was indicated to exert a key control on fluvial form and dynamics of the wetlands in the Kromrivier valley.
- Full Text:
- Date Issued: 2017
Contributions to the study of nonholonomic Riemannian manifolds
- Authors: Barrett, Dennis Ian
- Date: 2017
- Subjects: Riemannian manifolds , Curvature , Lie groups , Geometry, Riemannian , Tensor fields
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/7554 , vital:21272 , DOI https://doi.org/10.21504/10962/7554
- Description: In this thesis we consider nonholonomic Riemannian manifolds, and in particular, left- invariant nonholonomic Riemannian structures on Lie groups. These structures are closely related to mechanical systems with (positive definite) quadratic Lagrangians and nonholo- nomic constraints linear in velocities. In the first chapter, we review basic concepts of non- holonomic Riemannian geometry, including the left-invariant structures. We also examine the class of left-invariant structures with so-called Cartan-Schouten connections. The second chapter investigates the curvature of nonholonomic Riemannian manifolds and the Schouten and Wagner curvature tensors. The Schouten tensor is canonically associated to every non- holonomic Riemannian structure (in particular, we use it to define isometric invariants for structures on three-dimensional manifolds). By contrast, the Wagner tensor is not generally intrinsic, but can be used to characterise flat structures (i.e., those whose associated parallel transport is path-independent). The third chapter considers equivalence of nonholonomic Rie- mannian manifolds, particularly up to nonholonomic isometry. We also introduce the notion of a nonholonomic Riemannian submanifold, and investigate the conditions under which such a submanifold inherits its geometry from the enveloping space. The latter problem involves the concept of a geodesically invariant distribution, and we show it is also related to the curvature. In the last chapter we specialise to three-dimensional nonholonomic Riemannian manifolds. We consider the equivalence of such structures up to nonholonomic isometry and rescaling, and classify the left-invariant structures on the (three-dimensional) simply connected Lie groups. We also characterise the flat structures in three dimensions, and then classify the flat structures on the simply connected Lie groups. Lastly, we consider three typical examples of (left-invariant) nonholonomic Riemannian structures on three-dimensional Lie groups, two of which arise from problems in classical mechanics (viz., the Chaplygin problem and the Suslov problem). , Thesis (PhD) -- Faculty of Science, Mathematics (Pure and Applied), 2017
- Full Text:
- Date Issued: 2017
- Authors: Barrett, Dennis Ian
- Date: 2017
- Subjects: Riemannian manifolds , Curvature , Lie groups , Geometry, Riemannian , Tensor fields
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/7554 , vital:21272 , DOI https://doi.org/10.21504/10962/7554
- Description: In this thesis we consider nonholonomic Riemannian manifolds, and in particular, left- invariant nonholonomic Riemannian structures on Lie groups. These structures are closely related to mechanical systems with (positive definite) quadratic Lagrangians and nonholo- nomic constraints linear in velocities. In the first chapter, we review basic concepts of non- holonomic Riemannian geometry, including the left-invariant structures. We also examine the class of left-invariant structures with so-called Cartan-Schouten connections. The second chapter investigates the curvature of nonholonomic Riemannian manifolds and the Schouten and Wagner curvature tensors. The Schouten tensor is canonically associated to every non- holonomic Riemannian structure (in particular, we use it to define isometric invariants for structures on three-dimensional manifolds). By contrast, the Wagner tensor is not generally intrinsic, but can be used to characterise flat structures (i.e., those whose associated parallel transport is path-independent). The third chapter considers equivalence of nonholonomic Rie- mannian manifolds, particularly up to nonholonomic isometry. We also introduce the notion of a nonholonomic Riemannian submanifold, and investigate the conditions under which such a submanifold inherits its geometry from the enveloping space. The latter problem involves the concept of a geodesically invariant distribution, and we show it is also related to the curvature. In the last chapter we specialise to three-dimensional nonholonomic Riemannian manifolds. We consider the equivalence of such structures up to nonholonomic isometry and rescaling, and classify the left-invariant structures on the (three-dimensional) simply connected Lie groups. We also characterise the flat structures in three dimensions, and then classify the flat structures on the simply connected Lie groups. Lastly, we consider three typical examples of (left-invariant) nonholonomic Riemannian structures on three-dimensional Lie groups, two of which arise from problems in classical mechanics (viz., the Chaplygin problem and the Suslov problem). , Thesis (PhD) -- Faculty of Science, Mathematics (Pure and Applied), 2017
- Full Text:
- Date Issued: 2017