The androgenic and anabolic effects of pine pollen on Nile tilapia (Oreochromis niloticus)
- Authors: Abaho, Ivan
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431615 , vital:72790 , DOI 10.21504/10962/431615
- Description: All-male tilapia aquaculture is desirable to control unwanted breeding. Besides, male tilapia individuals grow faster and bigger than females. Presently, most farmers use 17α- methyltestosterone (MT) to produce an all-male stock, although the hormone is associated with human health and environmental risks. Recently, plant-based products have been reported to induce masculinisation in fish and are considered safe nature-based alternatives to MT. The present study utilised pine pollen (PP) to induce female-to-male sex change in Nile tilapia (Oreochromis niloticus). Prior to the start of the research, there was insufficient information on the use of PP for sex inversion, with no published data on the sex change mechanism, hence limiting the progress in the application of the product from experimental to hatchery levels. In this study, the optimal dietary inclusion of PP for maximum masculinisation of Nile tilapia was investigated by feeding three-day-old fish graded PP levels (80, 160, 320, 640, 1,280, 1,920, 2,560 and 3,200 mg kg-1 basal diet) from 3 to 30 days post-hatch (dph). This was compared with fish of the same batch fed the same basal diet with no PP (CT; negative control) or the same basal diet supplemented with 60 mg MT kg-1 (MT; positive control). To confirm whether the sex change was complete, fish in all treatments were fed only a basal diet for an additional 84 days. The associated differences in the growth of the fish were also determined. Pine pollen and MT significantly skewed the expected 50:50 (male: female) ratio towards more male individuals (Chi-square: X2 = 54.396, df = 9, P < 0.001). The 1,280 mg PP kg-1 of diet equally induced masculinisation (80.0 ± 2.9 % males) as MT (89.2 ± 2.2 %), and both were significantly higher than 50.8 ± 2.2 % in the CT treatment. In addition to masculinization, dietary inclusion of 1,280 mg PP kg-1 improved fish growth, with the specific growth rate significantly higher than fish from the MT and CT treatments (One-way ANOVA: F(9, 20) =14.196, P < 0.001). An increment in the dietary levels of PP from 1,280 to 3,200 mg kg-1 further promoted the growth of the fish but did not affect masculinisation. The mechanism underlying PP-induced sex masculinisation was investigated using all-female Nile tilapia fed a basal diet supplemented with 1,280 mg PP kg-1 for 28 days from 3 dph, in comparison with fish fed a basal diet incorporated with 60 mg MT kg-1 (MT treatment) or only a basal diet (CT treatment). The expression of sex-related genes (dmrt1, amh, cyp19a1a, and foxl2), changes in sex steroid profiles (T: testosterone, 11-KT: 11-ketotestosterone, and E2: 17β-estradiol), and gonadal histology were analysed. Gene expression and sex steroid concentrations were significantly influenced by the interaction between dietary treatment and time, with the expression changing differently over time among the treatments (RM-ANOVA: P < 0.001). Pine pollen significantly up-regulated the expression of dmrt1 and amh, while cyp19a1a and foxl2 were down-regulated. Corresponding to male sex gene up-regulation, male-based steroids (11-KT and T) levels were also significantly amplified in both PP and MTtreated fish. The gene expression pattern and changes in sex steroids corresponded to a higher proportion of male individuals obtained in the MT and PP treatments (MT: 97.8 ± 1.1 % and PP: 77.8 ± 2.9 % males), implying female-to-male sex change induction. Subsequently, spermatogonia and spermatocytes were the dominant germ cells in the histological sections of the gonads obtained from the PP-treated fish. At the same time, the individuals from the MT treatment exhibited mainly spermatids and spermatozoa. In contrast, all the fish from the CT treatment remained females, having only ovarian tissues. This thesis confirmed that PP induces female-to-male sex change in Nile tilapia and enhances fish growth. The research contributed novel information on the mechanism underlying PP induced sex change, which included disrupting the expression of sex genes and the androgento- estrogen balance, ultimately determining the sexual fate of the fish. The findings provide a foundation for understanding the role of PP in masculinisation, with broad potential application in the aquaculture industry. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Abaho, Ivan
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431615 , vital:72790 , DOI 10.21504/10962/431615
- Description: All-male tilapia aquaculture is desirable to control unwanted breeding. Besides, male tilapia individuals grow faster and bigger than females. Presently, most farmers use 17α- methyltestosterone (MT) to produce an all-male stock, although the hormone is associated with human health and environmental risks. Recently, plant-based products have been reported to induce masculinisation in fish and are considered safe nature-based alternatives to MT. The present study utilised pine pollen (PP) to induce female-to-male sex change in Nile tilapia (Oreochromis niloticus). Prior to the start of the research, there was insufficient information on the use of PP for sex inversion, with no published data on the sex change mechanism, hence limiting the progress in the application of the product from experimental to hatchery levels. In this study, the optimal dietary inclusion of PP for maximum masculinisation of Nile tilapia was investigated by feeding three-day-old fish graded PP levels (80, 160, 320, 640, 1,280, 1,920, 2,560 and 3,200 mg kg-1 basal diet) from 3 to 30 days post-hatch (dph). This was compared with fish of the same batch fed the same basal diet with no PP (CT; negative control) or the same basal diet supplemented with 60 mg MT kg-1 (MT; positive control). To confirm whether the sex change was complete, fish in all treatments were fed only a basal diet for an additional 84 days. The associated differences in the growth of the fish were also determined. Pine pollen and MT significantly skewed the expected 50:50 (male: female) ratio towards more male individuals (Chi-square: X2 = 54.396, df = 9, P < 0.001). The 1,280 mg PP kg-1 of diet equally induced masculinisation (80.0 ± 2.9 % males) as MT (89.2 ± 2.2 %), and both were significantly higher than 50.8 ± 2.2 % in the CT treatment. In addition to masculinization, dietary inclusion of 1,280 mg PP kg-1 improved fish growth, with the specific growth rate significantly higher than fish from the MT and CT treatments (One-way ANOVA: F(9, 20) =14.196, P < 0.001). An increment in the dietary levels of PP from 1,280 to 3,200 mg kg-1 further promoted the growth of the fish but did not affect masculinisation. The mechanism underlying PP-induced sex masculinisation was investigated using all-female Nile tilapia fed a basal diet supplemented with 1,280 mg PP kg-1 for 28 days from 3 dph, in comparison with fish fed a basal diet incorporated with 60 mg MT kg-1 (MT treatment) or only a basal diet (CT treatment). The expression of sex-related genes (dmrt1, amh, cyp19a1a, and foxl2), changes in sex steroid profiles (T: testosterone, 11-KT: 11-ketotestosterone, and E2: 17β-estradiol), and gonadal histology were analysed. Gene expression and sex steroid concentrations were significantly influenced by the interaction between dietary treatment and time, with the expression changing differently over time among the treatments (RM-ANOVA: P < 0.001). Pine pollen significantly up-regulated the expression of dmrt1 and amh, while cyp19a1a and foxl2 were down-regulated. Corresponding to male sex gene up-regulation, male-based steroids (11-KT and T) levels were also significantly amplified in both PP and MTtreated fish. The gene expression pattern and changes in sex steroids corresponded to a higher proportion of male individuals obtained in the MT and PP treatments (MT: 97.8 ± 1.1 % and PP: 77.8 ± 2.9 % males), implying female-to-male sex change induction. Subsequently, spermatogonia and spermatocytes were the dominant germ cells in the histological sections of the gonads obtained from the PP-treated fish. At the same time, the individuals from the MT treatment exhibited mainly spermatids and spermatozoa. In contrast, all the fish from the CT treatment remained females, having only ovarian tissues. This thesis confirmed that PP induces female-to-male sex change in Nile tilapia and enhances fish growth. The research contributed novel information on the mechanism underlying PP induced sex change, which included disrupting the expression of sex genes and the androgento- estrogen balance, ultimately determining the sexual fate of the fish. The findings provide a foundation for understanding the role of PP in masculinisation, with broad potential application in the aquaculture industry. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
- Full Text:
- Date Issued: 2023-10-13
Development of an enzyme-synergy based bioreactor system for the beneficiation of apple pomace lignocellulosic waste
- Authors: Abboo, Sagaran
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/315 , vital:19947
- Description: Due to the finite supply of non-renewable fossil fuels, agro-industrial wastes are identified as alternate, renewable sources for energy supply. Large amounts of fruit waste are generated in South Africa due to fruit juice and wine processing from apples, grapes and citrus fruit. Apple pomace is the solid residue that is left over after juice, cider and wine processing and constitutes between 25-30% of the total fruit. On a global scale millions of tonnes of apple pomace are produced; between 2006-2007 over 46 million tonnes were produced. In South Africa a total production of 244 469 tonnes were produced during the 2011- 2012 season. Initially, apple pomace was regarded as a waste by-product used for animal feed and compost in soil, however presently it is considered a source of dietary fiber and natural antioxidants like polyphenols. In addition, apple pomace has a high carbohydrate content and can be enzymatically hydrolysed to produce sugar monomers which, in turn, can be fermented by yeasts to produce bioethanol. The polyphenols present in apple pomace can be used for their health properties, and the bioethanol can be used as a replacement for fossil fuel. Apple pomace is lignocellulosic in nature and consists of hemicellulose, cellulose, lignin and pectin. A combination of enzymes such as cellulases, hemicellulases, pectinases and lignases are required to operate in synergy for the degradation of lignocellulosic biomass. This is due to the recalcitrant nature of lignocellulose. This study investigated the degradation of apple pomace using a combination of commercially obtained enzyme cocktails viz. Viscozyme L , Celluclast 1.5L and Novozyme 188. The commercial enzymes Viscozyme L and Celluclast 1.5L were added in a ratio of 1:1 (50%:50%). The final concentrations of the enzymes were 0.019 mg/ml each. Novozyme 188 was added to provide a final concentration of 0.0024 mg/ml. A novel cost effective 20L bioreactor was designed, constructed and implemented for the degradation of apple pomace to produce value added products. The hydrolysis of the apple pomace was performed initially in 1 L flasks (batch fed) and, once optimized, scaled up to a 20 L bioreactor in batch mode. The bioreactors were operated at room temperature (22 ± 2ºC) and in an unbuffered system. The sugars released were detected and quantified using an optimized validated HPLC method established in this study. The sugars released in the bioreactors were mainly glucose, galactose, arabinose, cellobiose and fructose. The polyphenols released in this study were gallic acid, catechin, epicatechin, chlorogenic acid, rutin and phloridzin, which have a number of health benefits. The simultaneous analyses of the polyphenols were performed using a newly developed and validated HPLC method established in this study. This method was developed to detect nine polyphenols simultaneously. The two HPLC methods developed and validated in this study for the analysis of sugars and polyphenols demonstrated good accuracy, precision, reproducibility, linearity, robustness and sensitivity. Both analytical methods were validated according to the International Convention on Harmonization (ICH). The HPLC parameters for sugar analysis were: refractive index (RI) as the detection mode, the stationary phase was a ligand-exchange sugar column (Shodex SP0810) and an aqueous mobile phase in isocratic mode was used. The HPLC method for polyphenols employed UV diode array detection (DAD) as the detection mode, a reverse phase column as the stationary phase and a mobile phase of consisting of 0.01 M phosphoric acid in water and 100% methanol using gradient elution mode. The highest concentrations of sugars released in the novel 20 L bioreactor with 20% apple pomace (w/v) substrate loading were as follow: glucose (6.5 mg/ml), followed by galactose (2.1 mg/ml), arabinose (1.4 mg/ml), cellobiose (0.7 mg/ml) and fructose (0.5 mg/ml). The amounts of polyphenols released at 20% (w/v) apple pomace substrate were epicatechin (0.01 mg/ml), catechin (0.002 mg/ml), rutin (0.03 mg/ml), chlorogenic acid (0.002 mg/ml) and gallic acid 0.01 (mg/ml). Two mathematical models were developed in this study for kinetic analysis of lignocellulose (apple pomace) hydrolysis in the novel 20 L bioreactor, using the experimental data generated by the above HPLC analyses. The first model, modelling with regression, defines the hydrolysis of the sugars glucose, galactose, cellobiose and arabinose produced in the novel 20 L bioreactor at 5%, 10%, 15% and 20% (w/v) substrate concentrations. The regression model describes the sugars produced in the 20 L bioreactor by minimizing the error of the sugars released by finding a value for K which minimises the function which computes the sum of squares of errors between the solution curves and the data points. The second, more complex, model developed in this study used a system of differential equations model (ODE). This model solved the system by using a numerical method, such as the Runge-Kutta method, then fitted the solution curves to the data. Both models simulated (and had the ability to predict) the production of sugars in the novel 20 L bioreactor for apple pomace hydrolysis. These two models also revealed the time at which the maximum amount of sugars were released, which revealed the optimum time to run the 20 L bioreactor in order to be more cost effective. The optimum time for maximum glucose (the main sugar used in fermentation for biofuel production) release was determined to be around 60 h. The ODE model, in addition, determined the rate at which the substrate became depleted, as well as the rate at which the enzymes became deactivated for the various substrate loadings in the 20 L bioreactor. A third model was developed to determine the optimal running cost of the bioreactor which incorporated the substrate loading and the amount of glucose (g/L) produced. The novel 20 L bioreactor constructed from cost effective materials demonstrated that agro-industrial waste can be converted to value-added products by lignocellolytic enzymes. The sugars released from apple pomace can be used in biofuel production and the polyphenols as food supplements and nutraceuticals for health benefits. This novel study contributes to agro-industrial waste beneficiation via fuel production. In addition, using agro-industrial waste for the generation of value added products (instead of mere disposal) will help prevent environmental pollution.
- Full Text:
- Date Issued: 2016
- Authors: Abboo, Sagaran
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/315 , vital:19947
- Description: Due to the finite supply of non-renewable fossil fuels, agro-industrial wastes are identified as alternate, renewable sources for energy supply. Large amounts of fruit waste are generated in South Africa due to fruit juice and wine processing from apples, grapes and citrus fruit. Apple pomace is the solid residue that is left over after juice, cider and wine processing and constitutes between 25-30% of the total fruit. On a global scale millions of tonnes of apple pomace are produced; between 2006-2007 over 46 million tonnes were produced. In South Africa a total production of 244 469 tonnes were produced during the 2011- 2012 season. Initially, apple pomace was regarded as a waste by-product used for animal feed and compost in soil, however presently it is considered a source of dietary fiber and natural antioxidants like polyphenols. In addition, apple pomace has a high carbohydrate content and can be enzymatically hydrolysed to produce sugar monomers which, in turn, can be fermented by yeasts to produce bioethanol. The polyphenols present in apple pomace can be used for their health properties, and the bioethanol can be used as a replacement for fossil fuel. Apple pomace is lignocellulosic in nature and consists of hemicellulose, cellulose, lignin and pectin. A combination of enzymes such as cellulases, hemicellulases, pectinases and lignases are required to operate in synergy for the degradation of lignocellulosic biomass. This is due to the recalcitrant nature of lignocellulose. This study investigated the degradation of apple pomace using a combination of commercially obtained enzyme cocktails viz. Viscozyme L , Celluclast 1.5L and Novozyme 188. The commercial enzymes Viscozyme L and Celluclast 1.5L were added in a ratio of 1:1 (50%:50%). The final concentrations of the enzymes were 0.019 mg/ml each. Novozyme 188 was added to provide a final concentration of 0.0024 mg/ml. A novel cost effective 20L bioreactor was designed, constructed and implemented for the degradation of apple pomace to produce value added products. The hydrolysis of the apple pomace was performed initially in 1 L flasks (batch fed) and, once optimized, scaled up to a 20 L bioreactor in batch mode. The bioreactors were operated at room temperature (22 ± 2ºC) and in an unbuffered system. The sugars released were detected and quantified using an optimized validated HPLC method established in this study. The sugars released in the bioreactors were mainly glucose, galactose, arabinose, cellobiose and fructose. The polyphenols released in this study were gallic acid, catechin, epicatechin, chlorogenic acid, rutin and phloridzin, which have a number of health benefits. The simultaneous analyses of the polyphenols were performed using a newly developed and validated HPLC method established in this study. This method was developed to detect nine polyphenols simultaneously. The two HPLC methods developed and validated in this study for the analysis of sugars and polyphenols demonstrated good accuracy, precision, reproducibility, linearity, robustness and sensitivity. Both analytical methods were validated according to the International Convention on Harmonization (ICH). The HPLC parameters for sugar analysis were: refractive index (RI) as the detection mode, the stationary phase was a ligand-exchange sugar column (Shodex SP0810) and an aqueous mobile phase in isocratic mode was used. The HPLC method for polyphenols employed UV diode array detection (DAD) as the detection mode, a reverse phase column as the stationary phase and a mobile phase of consisting of 0.01 M phosphoric acid in water and 100% methanol using gradient elution mode. The highest concentrations of sugars released in the novel 20 L bioreactor with 20% apple pomace (w/v) substrate loading were as follow: glucose (6.5 mg/ml), followed by galactose (2.1 mg/ml), arabinose (1.4 mg/ml), cellobiose (0.7 mg/ml) and fructose (0.5 mg/ml). The amounts of polyphenols released at 20% (w/v) apple pomace substrate were epicatechin (0.01 mg/ml), catechin (0.002 mg/ml), rutin (0.03 mg/ml), chlorogenic acid (0.002 mg/ml) and gallic acid 0.01 (mg/ml). Two mathematical models were developed in this study for kinetic analysis of lignocellulose (apple pomace) hydrolysis in the novel 20 L bioreactor, using the experimental data generated by the above HPLC analyses. The first model, modelling with regression, defines the hydrolysis of the sugars glucose, galactose, cellobiose and arabinose produced in the novel 20 L bioreactor at 5%, 10%, 15% and 20% (w/v) substrate concentrations. The regression model describes the sugars produced in the 20 L bioreactor by minimizing the error of the sugars released by finding a value for K which minimises the function which computes the sum of squares of errors between the solution curves and the data points. The second, more complex, model developed in this study used a system of differential equations model (ODE). This model solved the system by using a numerical method, such as the Runge-Kutta method, then fitted the solution curves to the data. Both models simulated (and had the ability to predict) the production of sugars in the novel 20 L bioreactor for apple pomace hydrolysis. These two models also revealed the time at which the maximum amount of sugars were released, which revealed the optimum time to run the 20 L bioreactor in order to be more cost effective. The optimum time for maximum glucose (the main sugar used in fermentation for biofuel production) release was determined to be around 60 h. The ODE model, in addition, determined the rate at which the substrate became depleted, as well as the rate at which the enzymes became deactivated for the various substrate loadings in the 20 L bioreactor. A third model was developed to determine the optimal running cost of the bioreactor which incorporated the substrate loading and the amount of glucose (g/L) produced. The novel 20 L bioreactor constructed from cost effective materials demonstrated that agro-industrial waste can be converted to value-added products by lignocellolytic enzymes. The sugars released from apple pomace can be used in biofuel production and the polyphenols as food supplements and nutraceuticals for health benefits. This novel study contributes to agro-industrial waste beneficiation via fuel production. In addition, using agro-industrial waste for the generation of value added products (instead of mere disposal) will help prevent environmental pollution.
- Full Text:
- Date Issued: 2016
Phenolic compounds in water and the implications for rapid detection of indicator micro-organisms using ß-D-Galactosidase and ß-D-Glucuronidase
- Authors: Abboo, Sagaran
- Date: 2009
- Subjects: Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3978 , http://hdl.handle.net/10962/d1004037 , Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Description: Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.
- Full Text:
- Date Issued: 2009
- Authors: Abboo, Sagaran
- Date: 2009
- Subjects: Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3978 , http://hdl.handle.net/10962/d1004037 , Water -- Purification -- Biological treatment , Pollutants -- Biodegradation , Phenol , Organic water pollutants , Water quality biological assessment , Water -- Pollution
- Description: Faecal contamination in water is detected using appropriate microbial models such as total coliforms, faecal coliforms and E. coli. Βeta-D-Galactosidase (β-GAL) and Beta-D-glucuronidase (β-GUD) are two marker enzymes that are used to test for the presence of total coliforms and E. coli in water samples, respectively. Various assay methods have been developed using chromogenic and fluorogenic substrates. In this study, the chromogenic substrates chlorophenol red β-D-galactopyranoside (CPRG) for β-GAL and p-nitrophenyl-β-D-galactopyranoside (PNPG) for β-GUD were used. Potential problems associated with this approach include interference from other organisms present in the environment (e.g. plants, algae and other bacteria), as well as the presence of certain chemicals, such as phenolic compounds in water. Phenolic compounds are present in the aquatic environment due to their extensive industrial applications. The USA Enviromental Protection Agency (EPA) lists 11 Priority Pollutant Phenols (PPP) due to their high level of toxicity. This study investigated the interfering effects of the eleven PPP found in water on the enzyme activities of both the β-GAL and β-GUD enzyme assays. The presence of these PPP in the β-GAL and β-GUD enzyme assays showed that over and underestimation of activity may occur due to inhibition or activation of these enzymes. Three types of inhibition to enzyme activities were identified from double reciprocal Lineweaver-Burk plots. The inhibition constants (Ki) were determined for all inhibitory phenolic compounds from appropriate secondary plots. Furthermore, this study presented a validated reverse phase high performance liquid chromatography (RP-HPLC) method, developed for the simultaneous detection, separation and determination of all eleven phenolic compounds found in the environment. This method demonstrated good linearity, reproducibility, accuracy and sensitivity. Environmental water samples were collected from rivers, streams, industrial sites and wastewater treatment plant effluent. These samples were extracted and concentrated using a solid phase extraction (SPE) procedure prior to analysis employing the newly developed HPLC method in this study. Seasonal variations on the presence of the PPP in the environment were observed at certain collection sites. The concentrations found were between 0.033 μg/ml for 2,4-dinitrophenol in a running stream to 0.890 mg/ml for pentachlorophenol from an tannery industrial site. These concentrations of phenolic compounds found in these environments were able to interfere with the β-GAL and β-GUD enzyme assays.
- Full Text:
- Date Issued: 2009
A review of asbestos resources
- Authors: Abbott, Paul
- Date: 1983
- Subjects: Asbestos Asbestos -- Geology Silicate minerals Mineralogy Chrysotile
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4910 , http://hdl.handle.net/10962/d1001570
- Full Text:
- Date Issued: 1983
- Authors: Abbott, Paul
- Date: 1983
- Subjects: Asbestos Asbestos -- Geology Silicate minerals Mineralogy Chrysotile
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4910 , http://hdl.handle.net/10962/d1001570
- Full Text:
- Date Issued: 1983
Genetic and biological characterisation of a novel South African Plutella xylostella granulovirus (PlxyGV) isolate
- Authors: Abdulkadir, Fatima
- Date: 2014
- Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
- Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
- Full Text:
- Date Issued: 2014
- Authors: Abdulkadir, Fatima
- Date: 2014
- Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
- Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
- Full Text:
- Date Issued: 2014
Colonial policies and the failure of Somali secessionism in the Northern frontier district of Kenya colony, c.1890-1968
- Authors: Abdullahi, Abdirashid
- Date: 1998
- Subjects: Somalis -- Kenya -- History , Kenya -- History -- 1963- , Kenya -- Politics and government , Decolonization -- Kenya -- History -- 20th century , Kenya -- History -- To 1963
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2532 , http://hdl.handle.net/10962/d1002384 , Somalis -- Kenya -- History , Kenya -- History -- 1963- , Kenya -- Politics and government , Decolonization -- Kenya -- History -- 20th century , Kenya -- History -- To 1963
- Description: This thesis examines the events that took plac,e. in the Northern Frontier District I North Eastern Province of Kenya hetween the late nineteenth century and 1968. After 1900 the imposition of colonial policies impacted on the socio-economic and political structures of the Somali people. This thesis also examines the nature of Somali resistance l\P- to the late 1920s when Somali society was finally pacified. It further examines colonial policies such as the creation of the Somali-Galla line in 1919, the separation of the J uhaland region from the Kenya Colony in 1926 and the Special District Ordinance of 1934. Between 1946 and 1948 the British Government through its Foreign Minister, Ernest Bevin, attempted to unify Somali territories in the Horn of Africa and this raised Somali hopes of uni fication. The Bevin Plan collapsed because of the opposition of the United States, the Soviet Union, the French and Ethiopian leaders. Similar hopes of NFD Somali unification were raised hetween 1958 and 1963 because of the unification of the former British Somali land and Italian Somaliland. Due to the imminent end of British colonial rule in Kenya, the NFD Somali leaders demanded secession from Kenya to join up with the nascent Somali republic. But the NFDSomali hopes of unification with the Somali Repuhlic were dashed by 1964 because of the same opposition provided by the United States, the French and the Ethiopians. The British Government were all along half-hearted towards Somali unification attempts even though the field administrators adopted a pro-Somali attitude to the issue. In the early 1960s, however, the NFD Somali leaders were faced with the additional opposition of the new KANU government in Kenya. In 1964 the failure of the NFD Somalis to secede from Kenya led to the guerrilla war, what the Kenyan government called the 'shifta movement', that engulfed the North Eastern Region until 1968 when the Arusha Memorandum of Understanding was signed between the Kenyan and the Somali Governments. The signing of the Arusha Memorandum of Understanding by the Kenyan and Somali Governments did not satisfy· the NFD Somalis hopes of joining the Somali Republic. The main conclusion of this thesis is that the N FD Somalis, except for few collahorators, did at no time, whether in the colonial or post-colonial eras, accept heing in Kenya. By the late 1960s the prospects of NFD Somalis unifying with the Somali Republic were, in view of the forces arrayed against the Somali secessionist movement, slim; and they have remained slim since then.
- Full Text:
- Date Issued: 1998
- Authors: Abdullahi, Abdirashid
- Date: 1998
- Subjects: Somalis -- Kenya -- History , Kenya -- History -- 1963- , Kenya -- Politics and government , Decolonization -- Kenya -- History -- 20th century , Kenya -- History -- To 1963
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2532 , http://hdl.handle.net/10962/d1002384 , Somalis -- Kenya -- History , Kenya -- History -- 1963- , Kenya -- Politics and government , Decolonization -- Kenya -- History -- 20th century , Kenya -- History -- To 1963
- Description: This thesis examines the events that took plac,e. in the Northern Frontier District I North Eastern Province of Kenya hetween the late nineteenth century and 1968. After 1900 the imposition of colonial policies impacted on the socio-economic and political structures of the Somali people. This thesis also examines the nature of Somali resistance l\P- to the late 1920s when Somali society was finally pacified. It further examines colonial policies such as the creation of the Somali-Galla line in 1919, the separation of the J uhaland region from the Kenya Colony in 1926 and the Special District Ordinance of 1934. Between 1946 and 1948 the British Government through its Foreign Minister, Ernest Bevin, attempted to unify Somali territories in the Horn of Africa and this raised Somali hopes of uni fication. The Bevin Plan collapsed because of the opposition of the United States, the Soviet Union, the French and Ethiopian leaders. Similar hopes of NFD Somali unification were raised hetween 1958 and 1963 because of the unification of the former British Somali land and Italian Somaliland. Due to the imminent end of British colonial rule in Kenya, the NFD Somali leaders demanded secession from Kenya to join up with the nascent Somali republic. But the NFDSomali hopes of unification with the Somali Repuhlic were dashed by 1964 because of the same opposition provided by the United States, the French and the Ethiopians. The British Government were all along half-hearted towards Somali unification attempts even though the field administrators adopted a pro-Somali attitude to the issue. In the early 1960s, however, the NFD Somali leaders were faced with the additional opposition of the new KANU government in Kenya. In 1964 the failure of the NFD Somalis to secede from Kenya led to the guerrilla war, what the Kenyan government called the 'shifta movement', that engulfed the North Eastern Region until 1968 when the Arusha Memorandum of Understanding was signed between the Kenyan and the Somali Governments. The signing of the Arusha Memorandum of Understanding by the Kenyan and Somali Governments did not satisfy· the NFD Somalis hopes of joining the Somali Republic. The main conclusion of this thesis is that the N FD Somalis, except for few collahorators, did at no time, whether in the colonial or post-colonial eras, accept heing in Kenya. By the late 1960s the prospects of NFD Somalis unifying with the Somali Republic were, in view of the forces arrayed against the Somali secessionist movement, slim; and they have remained slim since then.
- Full Text:
- Date Issued: 1998
An analytical study of narrative techniques in Giono's Regain
- Authors: Abel, Hermione
- Date: 1986
- Subjects: French fiction , Novels , Criticism , Symbolism , Regain , Giono, Jean, 1895-1970 -- Criticism and interpretation
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3561 , http://hdl.handle.net/10962/d1002008
- Description: The dominant theme in Regain is that of death leading to rebirth. This dissertation attempts to explore Giono's narrative techniques within this context. No single chapter will be devoted to a specific technique; instead, the various devices used by the author are discussed as they emerge from the structure of the chapters. Justifying the field of study as defined in the "Introduction", the following three chapters outline the passage of life from death to eventual rebirth. With acknowledgement to Frank Kermode, who writes: "A concord of past, present and future three dreams which, as Augustine said, cross in our minds, as in the present of things past, the present of things present, and the present of things future" ¹, the first three chapters bear his terminology for their headings. Chapter One, "The Present of Things Past", deals with Mameche's loss of her husband and son. Chapter Two, "The Present of Things Present", focuses upon Mameche' s realization of Gaubert's departure, and the decision that she must do something to save the dying village of Aubignane. Chapter Three, "The Present of Things Future", sees Mameche setting out in search of a wife for Panturle, and succeeding. This brings to an end Part One of the novel. Interwoven throughout the chapters are paradigms from Greek mythology, rich in universal symbolism, and the author's belief in man's ability to fuse himself with his surroundings. The conclusion summarizes the findings of this study, attempting to show how an analysis of Giono's narrative technique provides an insight into such a novel as Regain. ¹The Sense of an Ending (London: Oxford University Press, 1966), rpt., 1970, p. 50.
- Full Text:
- Date Issued: 1986
- Authors: Abel, Hermione
- Date: 1986
- Subjects: French fiction , Novels , Criticism , Symbolism , Regain , Giono, Jean, 1895-1970 -- Criticism and interpretation
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3561 , http://hdl.handle.net/10962/d1002008
- Description: The dominant theme in Regain is that of death leading to rebirth. This dissertation attempts to explore Giono's narrative techniques within this context. No single chapter will be devoted to a specific technique; instead, the various devices used by the author are discussed as they emerge from the structure of the chapters. Justifying the field of study as defined in the "Introduction", the following three chapters outline the passage of life from death to eventual rebirth. With acknowledgement to Frank Kermode, who writes: "A concord of past, present and future three dreams which, as Augustine said, cross in our minds, as in the present of things past, the present of things present, and the present of things future" ¹, the first three chapters bear his terminology for their headings. Chapter One, "The Present of Things Past", deals with Mameche's loss of her husband and son. Chapter Two, "The Present of Things Present", focuses upon Mameche' s realization of Gaubert's departure, and the decision that she must do something to save the dying village of Aubignane. Chapter Three, "The Present of Things Future", sees Mameche setting out in search of a wife for Panturle, and succeeding. This brings to an end Part One of the novel. Interwoven throughout the chapters are paradigms from Greek mythology, rich in universal symbolism, and the author's belief in man's ability to fuse himself with his surroundings. The conclusion summarizes the findings of this study, attempting to show how an analysis of Giono's narrative technique provides an insight into such a novel as Regain. ¹The Sense of an Ending (London: Oxford University Press, 1966), rpt., 1970, p. 50.
- Full Text:
- Date Issued: 1986
The implementation and evaluation of a service-learning component in a second year undergraduate organic chemistry course
- Authors: Abel, Sarah Ruth
- Date: 2011 , 2010-10-03
- Subjects: Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4393 , http://hdl.handle.net/10962/d1006008 , Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Description: The project describes the action research implementation, and evaluation of learning, of a service-learning component in a second year undergraduate organic chemistry course. The research aims to explore the learning that takes place in a service-learning context while utilizing an action research methodology within the critical theory paradigm. This occurs in response to the world-wide call for Higher Education to produce people with civic competencies and responsiveness to the society in which they live (Boyer 1996). Educating young Chemists to see the importance of their knowledge and their responsibilities in society is an important pedagogical step in the effort to cross boundaries and make connections between people communities (Eyler and Giles 1999). The goal of this project was to explore and categorize the learning that takes place in a service-learning context and discover how these areas of learning impact the awareness of the parties involved with regard to the discipline of chemistry as well as social issues. The project makes use of Kolb‘s (1984) Experiential Learning Theory, and Eyler and Giles‘ (1999) categories of learning in service-learning and results indicate that service-learning can be a powerful pedagogical tool to increase learning in chemistry as well as in the areas of critical thinking, personal and social development, reflection and citizenship. Students‘ perceptions of themselves, their discipline and their responsibility to society were transformed by their experience of service-learning in their undergraduate chemistry course.
- Full Text:
- Date Issued: 2011
- Authors: Abel, Sarah Ruth
- Date: 2011 , 2010-10-03
- Subjects: Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4393 , http://hdl.handle.net/10962/d1006008 , Chemistry, Organic -- Study and teaching (Higher) -- South Africa , Action research in education -- South Africa , Experiential learning -- South Africa , Service learning -- South Africa
- Description: The project describes the action research implementation, and evaluation of learning, of a service-learning component in a second year undergraduate organic chemistry course. The research aims to explore the learning that takes place in a service-learning context while utilizing an action research methodology within the critical theory paradigm. This occurs in response to the world-wide call for Higher Education to produce people with civic competencies and responsiveness to the society in which they live (Boyer 1996). Educating young Chemists to see the importance of their knowledge and their responsibilities in society is an important pedagogical step in the effort to cross boundaries and make connections between people communities (Eyler and Giles 1999). The goal of this project was to explore and categorize the learning that takes place in a service-learning context and discover how these areas of learning impact the awareness of the parties involved with regard to the discipline of chemistry as well as social issues. The project makes use of Kolb‘s (1984) Experiential Learning Theory, and Eyler and Giles‘ (1999) categories of learning in service-learning and results indicate that service-learning can be a powerful pedagogical tool to increase learning in chemistry as well as in the areas of critical thinking, personal and social development, reflection and citizenship. Students‘ perceptions of themselves, their discipline and their responsibility to society were transformed by their experience of service-learning in their undergraduate chemistry course.
- Full Text:
- Date Issued: 2011
Exploring targeted metagenomics and untargeted metabolomics for characterising aquaponics bacterial ecology and phytochemistry
- Authors: Abraham, Benjamin Melakail
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192453 , vital:45227
- Description: Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Abraham, Benjamin Melakail
- Date: 2021-10-29
- Subjects: Uncatalogued
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192453 , vital:45227
- Description: Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-10-29
Photosynthetic and growth response of C₃ and C₄ subspecies of Alloteropsis semialata to nitrogen-supply
- Authors: Abraham, Trevor Ian
- Date: 2008
- Subjects: Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4182 , http://hdl.handle.net/10962/d1003750 , Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Description: The greater photosynthetic nitrogen use efficiency (PNUE) of C4 compared with C3 plants may explain the relative success of C4 grasses in nutrient poor environments. This study compared the responses in photosynthetic parameters, leaf nitrogen and biomass allocation between the C3 and C4 subspecies of Alloteropsis semialata supplied soil nitrogen at three levels. Photosynthesis was assessed by means of CO2 response curves and the leaf nitrogen content assayed. Plants were destructively harvested, leaf areas determined and the dry biomass of functional plant components was measured. Results confirmed that the higher PNUE of C4 plants allowed them to accumulate more biomass than C3 plants at the high nitrogen level, despite smaller leaf areas. The greater productivity of C4 plants enabled them to invest more in storage and sexual reproduction than in leaves when compared to the C3 plants. In contrast the C3 plants invested biomass in less efficient and more nitrogen demanding leaves and bigger root systems. PNUE and photosynthetic rates were not significantly affected by nitrogen-limitation in either subspecies and the major response was a decrease in biomass accumulation and an increase in biomass allocation to roots. This altered root to shoot ratio was accompanied by a lowered allocation to sexual reproduction in the C4 subspecies, but an unaltered allocation to leaves, while in the C3 subspecies there was a decrease in leaf allocation. In a further experiment, the C4 subspecies was supplied three levels of nitrogen provided as nitrate, or alternatively as ammonium plus nitrate, and leaves were excised to within 5 cm of the ground at the start of treatment. Prior to flowering, photosynthesis was assessed by means of CO2 response curves and the plants were destructively harvested. Leaf areas and the dry biomass of functional plant components were determined, and at levels of nitrogen supply higher than those found in savanna soils the rate of photosynthesis was increased. Leaf re-growth was reduced by severe nitrogen limitation and co-provision of nitrate and ammonium had no significant effect other than increased tillering. Both subspecies of Alloteropsis semialata are adapted to nutrient poor environments and maintain photosynthetic rates by reducing leaf area. The C4 subspecies is likely to show greater resilience in disturbance-prone environments by exploiting its higher PNUE to allocate greater resources to storage and sexual reproduction, while the C3 subspecies is usually found in environments with closed canopies which favour vegetative growth, and allocate greater resources to leaves and roots.
- Full Text:
- Date Issued: 2008
- Authors: Abraham, Trevor Ian
- Date: 2008
- Subjects: Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4182 , http://hdl.handle.net/10962/d1003750 , Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Description: The greater photosynthetic nitrogen use efficiency (PNUE) of C4 compared with C3 plants may explain the relative success of C4 grasses in nutrient poor environments. This study compared the responses in photosynthetic parameters, leaf nitrogen and biomass allocation between the C3 and C4 subspecies of Alloteropsis semialata supplied soil nitrogen at three levels. Photosynthesis was assessed by means of CO2 response curves and the leaf nitrogen content assayed. Plants were destructively harvested, leaf areas determined and the dry biomass of functional plant components was measured. Results confirmed that the higher PNUE of C4 plants allowed them to accumulate more biomass than C3 plants at the high nitrogen level, despite smaller leaf areas. The greater productivity of C4 plants enabled them to invest more in storage and sexual reproduction than in leaves when compared to the C3 plants. In contrast the C3 plants invested biomass in less efficient and more nitrogen demanding leaves and bigger root systems. PNUE and photosynthetic rates were not significantly affected by nitrogen-limitation in either subspecies and the major response was a decrease in biomass accumulation and an increase in biomass allocation to roots. This altered root to shoot ratio was accompanied by a lowered allocation to sexual reproduction in the C4 subspecies, but an unaltered allocation to leaves, while in the C3 subspecies there was a decrease in leaf allocation. In a further experiment, the C4 subspecies was supplied three levels of nitrogen provided as nitrate, or alternatively as ammonium plus nitrate, and leaves were excised to within 5 cm of the ground at the start of treatment. Prior to flowering, photosynthesis was assessed by means of CO2 response curves and the plants were destructively harvested. Leaf areas and the dry biomass of functional plant components were determined, and at levels of nitrogen supply higher than those found in savanna soils the rate of photosynthesis was increased. Leaf re-growth was reduced by severe nitrogen limitation and co-provision of nitrate and ammonium had no significant effect other than increased tillering. Both subspecies of Alloteropsis semialata are adapted to nutrient poor environments and maintain photosynthetic rates by reducing leaf area. The C4 subspecies is likely to show greater resilience in disturbance-prone environments by exploiting its higher PNUE to allocate greater resources to storage and sexual reproduction, while the C3 subspecies is usually found in environments with closed canopies which favour vegetative growth, and allocate greater resources to leaves and roots.
- Full Text:
- Date Issued: 2008
Understanding of biological teleology from a naturalistic perspective
- Authors: Abrahams, Sanaa
- Date: 2020
- Subjects: Teleology , Biology -- Philosophy , Evolution (Biology) -- Philosophy
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140534 , vital:37896
- Description: To the extent that teleological thinking is metaphysically suspect, many theorists attempt to shift the stigma of functional explanations by reducing function ascriptions, and aim thus to de-legitimise an appeal to teleological causal relations in an analysis of function. The point is to dispel the mystery which envelops the application of function concepts by reformulating biological functional explanations so as to dispense with teleology. My project is to interrogate the success with which teleological explanations have thus been eliminated in the biological sciences, and, over the course of this thesis, I conclude that a kind of teleological causation nevertheless remains the most adequate explanatory ground of natural products. My proposal is that functional explanations are causal explanations for the presence and maintenance of self-reproducing systems. I contend that, insofar as the attribution of function presupposes the valuation of a function-bearing system as a causal necessity for its constituent parts, functional explanation references distinct and irreducible holistic properties. Using Kantian metaphysics to frame the discussion, this thesis aims first to explore critically the subject of functional characterisations of biological phenomena, and second, the metaphysical basis of modern science. Its chief contributions to the philosophical function debate reside in proposing novel arguments in justification of what I consider is an improved formulation of an attempted definition of biological function, in which teleological causal powers are explicitly recognised and accommodated in functional explanation. Moreover, this thesis attempts a naturalistic reconstruction of the metaphysical entailments of the real causality of a whole
- Full Text:
- Date Issued: 2020
- Authors: Abrahams, Sanaa
- Date: 2020
- Subjects: Teleology , Biology -- Philosophy , Evolution (Biology) -- Philosophy
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140534 , vital:37896
- Description: To the extent that teleological thinking is metaphysically suspect, many theorists attempt to shift the stigma of functional explanations by reducing function ascriptions, and aim thus to de-legitimise an appeal to teleological causal relations in an analysis of function. The point is to dispel the mystery which envelops the application of function concepts by reformulating biological functional explanations so as to dispense with teleology. My project is to interrogate the success with which teleological explanations have thus been eliminated in the biological sciences, and, over the course of this thesis, I conclude that a kind of teleological causation nevertheless remains the most adequate explanatory ground of natural products. My proposal is that functional explanations are causal explanations for the presence and maintenance of self-reproducing systems. I contend that, insofar as the attribution of function presupposes the valuation of a function-bearing system as a causal necessity for its constituent parts, functional explanation references distinct and irreducible holistic properties. Using Kantian metaphysics to frame the discussion, this thesis aims first to explore critically the subject of functional characterisations of biological phenomena, and second, the metaphysical basis of modern science. Its chief contributions to the philosophical function debate reside in proposing novel arguments in justification of what I consider is an improved formulation of an attempted definition of biological function, in which teleological causal powers are explicitly recognised and accommodated in functional explanation. Moreover, this thesis attempts a naturalistic reconstruction of the metaphysical entailments of the real causality of a whole
- Full Text:
- Date Issued: 2020
Massed prolonged exposure therapy for PTSD and alcohol use: a single case experimental study of a university student
- Authors: Abrahams, Sherwin Owen
- Date: 2025-04-25
- Subjects: Prolonged exposure therapy , Post-traumatic stress disorder , Alcoholism , Flooding , College students Alcohol use South Africa , College students Psychology
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/478284 , vital:78173
- Description: Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are common among university students in South Africa. Bantjies et al. (2023) found a PTSD prevalence of 21.0% (n=28,268), and McGowan and Kagee (2013) reported that 90% (n=1337) had experienced at least one traumatic event. There is a high comorbidity between PTSD and AUD, especially in hazardous drinkers (Peltzer & Pengpid, 2015). Despite the prevalence, research on effective trauma-focused therapies (TFTs) in low-resource settings is limited (Booysen & Kagee, 2021). This study evaluates the effectiveness of massed-prolonged exposure (MPE) therapy for comorbid PTSD and AUD among South African university students, using a Single-Case Experimental Design (SCED). The participant (n=1) underwent comprehensive assessments using CAPS-5, AUDIT, PDS-5, and PCL-5, confirming PTSD and AUD diagnoses. Regular PCL-5 assessments during the intervention showed significant symptom improvement, and post-intervention assessments indicated the participant no longer met PTSD criteria. AUDIT scores also improved from 11 (harmful/hazardous drinking) to 6. The participant found MPE therapy to be feasible, acceptable, and appropriate. This study supports the effectiveness, feasibility and acceptability of MPE therapy and highlights the importance of evidence-based interventions to improve PTSD outcomes within university settings and in low-to-middle-income countries. , Thesis (MA) -- Faculty of Humanities, Psychology, 2025
- Full Text:
- Date Issued: 2025-04-25
- Authors: Abrahams, Sherwin Owen
- Date: 2025-04-25
- Subjects: Prolonged exposure therapy , Post-traumatic stress disorder , Alcoholism , Flooding , College students Alcohol use South Africa , College students Psychology
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/478284 , vital:78173
- Description: Post-traumatic stress disorder (PTSD) and alcohol use disorder (AUD) are common among university students in South Africa. Bantjies et al. (2023) found a PTSD prevalence of 21.0% (n=28,268), and McGowan and Kagee (2013) reported that 90% (n=1337) had experienced at least one traumatic event. There is a high comorbidity between PTSD and AUD, especially in hazardous drinkers (Peltzer & Pengpid, 2015). Despite the prevalence, research on effective trauma-focused therapies (TFTs) in low-resource settings is limited (Booysen & Kagee, 2021). This study evaluates the effectiveness of massed-prolonged exposure (MPE) therapy for comorbid PTSD and AUD among South African university students, using a Single-Case Experimental Design (SCED). The participant (n=1) underwent comprehensive assessments using CAPS-5, AUDIT, PDS-5, and PCL-5, confirming PTSD and AUD diagnoses. Regular PCL-5 assessments during the intervention showed significant symptom improvement, and post-intervention assessments indicated the participant no longer met PTSD criteria. AUDIT scores also improved from 11 (harmful/hazardous drinking) to 6. The participant found MPE therapy to be feasible, acceptable, and appropriate. This study supports the effectiveness, feasibility and acceptability of MPE therapy and highlights the importance of evidence-based interventions to improve PTSD outcomes within university settings and in low-to-middle-income countries. , Thesis (MA) -- Faculty of Humanities, Psychology, 2025
- Full Text:
- Date Issued: 2025-04-25
Decentralization and quality assurance in the Ugandan primary education sector
- Authors: Abu-Baker, Mutaaya Sirajee
- Date: 2018
- Subjects: Schools -- Decentralization -- Uganda , Education, Primary -- Uganda , Educational change -- Uganda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57390 , vital:26897
- Description: The study presented in this thesis is a case study analysis of decentralization and quality assurance in a decentralized set up of the Ugandan Primary Schooling. The research looked at how the monitoring and evaluation informed the policy formulation process to regulate quality assurance in a decentralized governance of primary education. The Study was positioned in the critical realist paradigm, interpretive in orientation and used both coding and thematic techniques to understand the teachers’, SMC members’, and officers’ (at district and ministry levels) experiences and perceptions of quality assurance in a decentralized set up. Data was gathered using interviews, document analysis and observation methods. The findings indicated that the study was affected by eleven themes: Management System and Leadership, Human Resource Management, Finance Administration and Management, Parenting and Nutrition, Politics, Motivation, Social Structures and Patterns, Legislative Process and Policies, Infrastructure Development and Management, Community Involvement in Education and Curriculum and Professionalism. The monitoring and evaluation system had a framework in which it operates, though there was no quality assurance policy to guide the provision of quality education. The study finally indicated that there are more threats in a decentralized set up that put Quality in danger. Secondly, there was absence of supervision/inspection in schools as there was no evidence to prove this due to absence of reports. However, document analysis indicated visits of officers to schools. Records management was a problem to schools. Decentralization was adopted at different levels by different countries to address specific problems identified in view of service delivery. Finally, though monitoring and evaluation results informed the policy and decision makers, there was no quality assurance policy to guide the provision of quality education in institutions.
- Full Text:
- Date Issued: 2018
- Authors: Abu-Baker, Mutaaya Sirajee
- Date: 2018
- Subjects: Schools -- Decentralization -- Uganda , Education, Primary -- Uganda , Educational change -- Uganda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57390 , vital:26897
- Description: The study presented in this thesis is a case study analysis of decentralization and quality assurance in a decentralized set up of the Ugandan Primary Schooling. The research looked at how the monitoring and evaluation informed the policy formulation process to regulate quality assurance in a decentralized governance of primary education. The Study was positioned in the critical realist paradigm, interpretive in orientation and used both coding and thematic techniques to understand the teachers’, SMC members’, and officers’ (at district and ministry levels) experiences and perceptions of quality assurance in a decentralized set up. Data was gathered using interviews, document analysis and observation methods. The findings indicated that the study was affected by eleven themes: Management System and Leadership, Human Resource Management, Finance Administration and Management, Parenting and Nutrition, Politics, Motivation, Social Structures and Patterns, Legislative Process and Policies, Infrastructure Development and Management, Community Involvement in Education and Curriculum and Professionalism. The monitoring and evaluation system had a framework in which it operates, though there was no quality assurance policy to guide the provision of quality education. The study finally indicated that there are more threats in a decentralized set up that put Quality in danger. Secondly, there was absence of supervision/inspection in schools as there was no evidence to prove this due to absence of reports. However, document analysis indicated visits of officers to schools. Records management was a problem to schools. Decentralization was adopted at different levels by different countries to address specific problems identified in view of service delivery. Finally, though monitoring and evaluation results informed the policy and decision makers, there was no quality assurance policy to guide the provision of quality education in institutions.
- Full Text:
- Date Issued: 2018
Relative contribution of wild foods to individual and household food security in the context of increasing vulnerability due to HIV/AIDS and climate variability
- Abu-Basutu, Keitometsi Ngulube
- Authors: Abu-Basutu, Keitometsi Ngulube
- Date: 2014
- Subjects: Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4774 , http://hdl.handle.net/10962/d1010864 , Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Description: Wild foods are an integral component of the household food basket, yet their quantified contribution to food security relative to other sources in the context of HIV/AIDS, climate change and variability remains underexplored. This study was carried out in Willowvale and Lesseyton which are rural communities in the Eastern Cape province of South Africa. Willowvale is a relatively remote, medium-rainfall coastal community, while Lesseyton is a peri-urban low rainfall inland community. Qualitative and quantitative methods were used to collect data from 78 HIV/AIDS afflicted households with 329 individuals and 87 non-afflicted households with 365 individuals in the two study sites. Households were visited quarterly over 12 months to assess food acquisition methods, dietary intake and quality, and levels of food security, and to determine strategies employed by households to cope with droughts. The wild foods investigated were wild meat, wild birds, wild fish, wild mushrooms, wild leafy vegetables and wild fruits. Diets were moderately well-balanced and limited in variety, with cereal items contributing 52 % to total calorie intake. Mid-upper arm circumference measurements showed that all respondents were adequately nourished. The bulk of the food consumed by households was purchased, with supplementation from own production, wild vegetables and wild fruits. In Willowvale, wild vegetables comprised 46 % of overall vegetable consumption for afflicted households and 32 % for non-afflicted households, while own fruit production comprised 100 % of fruit consumption. In Lesseyton, wild vegetables comprised only 6 % and 4 % of vegetable consumption for afflicted and non-afflicted households, while wild fruit comprised 63 % and 41 % for afflicted and non-afflicted households. More than 80 % of respondents from both afflicted and non-afflicted households had sufficient daily kilocalories, although the majority of afflicted households felt they were food insecure and sometimes collected wild foods as one of their multiple coping strategies. Hunting and gathering of wild foods was associated with site, household affliction status, gender, age and season. More than 80 % of respondents ate wild vegetables and said they were more drought tolerant than conventional vegetables, making them the most consumed wild food and approximately 16 % of respondents ate wild birds, making them the least consumed wild food. Approximately 14 % of respondents from afflicted households in Willowvale sold wild fish, whilst 34 % of respondents from afflicted households and 7 % from non-afflicted households sold wild fruits in Lesseyton. Strategies adopted by households to cope with droughts were different between the two study sites, and households in Willowvale used a wider range of strategies. Given the devastating effects of HIV/AIDS coupled with the drawbacks of climate change and variability on food security, wild foods represent a free and easy way for vulnerable households to obtain food.
- Full Text:
- Date Issued: 2014
- Authors: Abu-Basutu, Keitometsi Ngulube
- Date: 2014
- Subjects: Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4774 , http://hdl.handle.net/10962/d1010864 , Wild foods -- South Africa -- Eastern Cape , Food security -- South Africa , Food supply -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , HIV infections -- Social aspects -- South Africa , Chronically ill -- South Africa -- Economic conditions , Chronically ill -- South Africa -- Social conditions , Food -- Social aspects -- South Africa , Food -- Economic aspects -- South Africa
- Description: Wild foods are an integral component of the household food basket, yet their quantified contribution to food security relative to other sources in the context of HIV/AIDS, climate change and variability remains underexplored. This study was carried out in Willowvale and Lesseyton which are rural communities in the Eastern Cape province of South Africa. Willowvale is a relatively remote, medium-rainfall coastal community, while Lesseyton is a peri-urban low rainfall inland community. Qualitative and quantitative methods were used to collect data from 78 HIV/AIDS afflicted households with 329 individuals and 87 non-afflicted households with 365 individuals in the two study sites. Households were visited quarterly over 12 months to assess food acquisition methods, dietary intake and quality, and levels of food security, and to determine strategies employed by households to cope with droughts. The wild foods investigated were wild meat, wild birds, wild fish, wild mushrooms, wild leafy vegetables and wild fruits. Diets were moderately well-balanced and limited in variety, with cereal items contributing 52 % to total calorie intake. Mid-upper arm circumference measurements showed that all respondents were adequately nourished. The bulk of the food consumed by households was purchased, with supplementation from own production, wild vegetables and wild fruits. In Willowvale, wild vegetables comprised 46 % of overall vegetable consumption for afflicted households and 32 % for non-afflicted households, while own fruit production comprised 100 % of fruit consumption. In Lesseyton, wild vegetables comprised only 6 % and 4 % of vegetable consumption for afflicted and non-afflicted households, while wild fruit comprised 63 % and 41 % for afflicted and non-afflicted households. More than 80 % of respondents from both afflicted and non-afflicted households had sufficient daily kilocalories, although the majority of afflicted households felt they were food insecure and sometimes collected wild foods as one of their multiple coping strategies. Hunting and gathering of wild foods was associated with site, household affliction status, gender, age and season. More than 80 % of respondents ate wild vegetables and said they were more drought tolerant than conventional vegetables, making them the most consumed wild food and approximately 16 % of respondents ate wild birds, making them the least consumed wild food. Approximately 14 % of respondents from afflicted households in Willowvale sold wild fish, whilst 34 % of respondents from afflicted households and 7 % from non-afflicted households sold wild fruits in Lesseyton. Strategies adopted by households to cope with droughts were different between the two study sites, and households in Willowvale used a wider range of strategies. Given the devastating effects of HIV/AIDS coupled with the drawbacks of climate change and variability on food security, wild foods represent a free and easy way for vulnerable households to obtain food.
- Full Text:
- Date Issued: 2014
Exploring the diverse racialised responses to the ‘Ashwin Willemse incident’ through theories of race and coloniality of being
- Authors: Accom, Abner
- Date: 2022-10-14
- Subjects: Willemse, Ashwin, 1981- , Ethnic attitudes South Africa , Race awareness South Africa , Postcolonialism South Africa , South Africa Race relations , Decolonization South Africa , Racism in sports South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/405908 , vital:70218
- Description: On 19 May 2018 Ashwin Willemse, a coloured Springbok rugby player walked off the SuperSport set, a DSTV sports program, during a live broadcast. He accused his white co-hosts Nick Mallet and Naas Botha (two white apartheid-era Springboks) of patronising him (SABC News, 2018; Eyewitness News, 2018). Responses to the Willemse incident reflected racial divisions in the country. It appeared that many white South Africans criticised Willemse’s behaviour, while many black South Africans stated that they could identify with his response to the subtle racisms experienced in everyday life, and which he claimed to have experienced on the SuperSport program (SABC News, 2018; Eyewitness News, 2018). The racialised media outcry led Professor Jonathan Jansen, to ask: “why do two groups of people, staring at the same event ‘see’ two different realities” (Maleka, 2018: 4)? This thesis probes possible answers to Jonathan Jansen’s question regarding the Ashwin Willemse walkout. The thesis explores and analyses the diverse racialised responses to the ‘Willemse walkout’ through race theories and ‘coloniality of being’. Qualitative research methods were used in the form of a reception analysis involving two racially homogenous (black and white) focus group interviews, two in-depth individual interviews with black research participants, three in-depth individual interviews with white research participants, and a sample of tweets from black and white commentators who had opinions about the ‘Willemse walkout’. The thesis concludes that most black research participants supported Willemse’s actions and most of the white people in the group disagreed with Willemse’s behaviour. Their various opinions were largely due to their different lived experiences which were a consequence of South Africa’s colonial history, apartheid, and racial discrimination. , Thesis (MA) -- Faculty of Humanities, School of Journalism and Media Studies, 2022
- Full Text:
- Date Issued: 2022-10-14
- Authors: Accom, Abner
- Date: 2022-10-14
- Subjects: Willemse, Ashwin, 1981- , Ethnic attitudes South Africa , Race awareness South Africa , Postcolonialism South Africa , South Africa Race relations , Decolonization South Africa , Racism in sports South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/405908 , vital:70218
- Description: On 19 May 2018 Ashwin Willemse, a coloured Springbok rugby player walked off the SuperSport set, a DSTV sports program, during a live broadcast. He accused his white co-hosts Nick Mallet and Naas Botha (two white apartheid-era Springboks) of patronising him (SABC News, 2018; Eyewitness News, 2018). Responses to the Willemse incident reflected racial divisions in the country. It appeared that many white South Africans criticised Willemse’s behaviour, while many black South Africans stated that they could identify with his response to the subtle racisms experienced in everyday life, and which he claimed to have experienced on the SuperSport program (SABC News, 2018; Eyewitness News, 2018). The racialised media outcry led Professor Jonathan Jansen, to ask: “why do two groups of people, staring at the same event ‘see’ two different realities” (Maleka, 2018: 4)? This thesis probes possible answers to Jonathan Jansen’s question regarding the Ashwin Willemse walkout. The thesis explores and analyses the diverse racialised responses to the ‘Willemse walkout’ through race theories and ‘coloniality of being’. Qualitative research methods were used in the form of a reception analysis involving two racially homogenous (black and white) focus group interviews, two in-depth individual interviews with black research participants, three in-depth individual interviews with white research participants, and a sample of tweets from black and white commentators who had opinions about the ‘Willemse walkout’. The thesis concludes that most black research participants supported Willemse’s actions and most of the white people in the group disagreed with Willemse’s behaviour. Their various opinions were largely due to their different lived experiences which were a consequence of South Africa’s colonial history, apartheid, and racial discrimination. , Thesis (MA) -- Faculty of Humanities, School of Journalism and Media Studies, 2022
- Full Text:
- Date Issued: 2022-10-14
An investigation of the learning processes that take place during practical work activities when using electrical circuit boards in grade: a case study
- Authors: Accom, Gerald Charles
- Date: 2012
- Subjects: Competency-based education -- South Africa -- Eastern Cape -- Case studies Educational tests and measurements -- South Africa -- Eastern Cape -- Case studies Education -- Evaluation -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1961 , http://hdl.handle.net/10962/d1009687
- Description: Since the introduction of Outcomes Based Education (OBE) as a preferred method of teaching and learning with Curriculum 2005 in 1997, its existence has come under continuous threat for the past thirteen years. Its teething experiences included a revision in 2004 which saw the introduction of the Revised National Curriculum Statements (RNCS) and most recently, we are now standing on the threshold of the implementation of the Curriculum Assessment Policy Statements (CAPS) in 2012. Throughout the turbulent educational milieu, social constructivism has always been upheld as the preferred teaching and learning methodology and millions of rands have been invested in this regard. This study is thus premised on the concern that now after all the years of actively promoting social constructivist methodologies, the implementation of the CAPS could seriously negate reasonable strides made in this regard. Triggered by these curricular issues, a qualitative case study was conducted at a school in Grahamstown in the Eastern Cape, South Africa, investigating the learning processes occurring in group work sessions during lessons involving practical work in electricity using circuit boards in grade 8. Underpinned by an interpretivist paradigm, the study took place in two phases. The data was mainly generated through audio and video recording of two focus groups. An open coding system was employed to derive analytical categories and frequency tables were used to establish trends. In order to validate the data, two observer teachers were involved throughout the research process and this was followed up with semistructured interviews after the second phase. The two case studies, involving learners fitting a similar profile in respect of mother-tongue and age group, were engaged in a similar activity for almost a year apart. This study anticipated the revelation of the extent to which group practical activities in electricity promoted learning, how knowledge is constructed in group-settings and whether practical activities involving electrical circuit boards in grade 8 enhance learning? The main findings of my study revealed that these practical activities can promote learning and therefore should remain a preferred method of teaching.
- Full Text:
- Date Issued: 2012
- Authors: Accom, Gerald Charles
- Date: 2012
- Subjects: Competency-based education -- South Africa -- Eastern Cape -- Case studies Educational tests and measurements -- South Africa -- Eastern Cape -- Case studies Education -- Evaluation -- South Africa -- Eastern Cape -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1961 , http://hdl.handle.net/10962/d1009687
- Description: Since the introduction of Outcomes Based Education (OBE) as a preferred method of teaching and learning with Curriculum 2005 in 1997, its existence has come under continuous threat for the past thirteen years. Its teething experiences included a revision in 2004 which saw the introduction of the Revised National Curriculum Statements (RNCS) and most recently, we are now standing on the threshold of the implementation of the Curriculum Assessment Policy Statements (CAPS) in 2012. Throughout the turbulent educational milieu, social constructivism has always been upheld as the preferred teaching and learning methodology and millions of rands have been invested in this regard. This study is thus premised on the concern that now after all the years of actively promoting social constructivist methodologies, the implementation of the CAPS could seriously negate reasonable strides made in this regard. Triggered by these curricular issues, a qualitative case study was conducted at a school in Grahamstown in the Eastern Cape, South Africa, investigating the learning processes occurring in group work sessions during lessons involving practical work in electricity using circuit boards in grade 8. Underpinned by an interpretivist paradigm, the study took place in two phases. The data was mainly generated through audio and video recording of two focus groups. An open coding system was employed to derive analytical categories and frequency tables were used to establish trends. In order to validate the data, two observer teachers were involved throughout the research process and this was followed up with semistructured interviews after the second phase. The two case studies, involving learners fitting a similar profile in respect of mother-tongue and age group, were engaged in a similar activity for almost a year apart. This study anticipated the revelation of the extent to which group practical activities in electricity promoted learning, how knowledge is constructed in group-settings and whether practical activities involving electrical circuit boards in grade 8 enhance learning? The main findings of my study revealed that these practical activities can promote learning and therefore should remain a preferred method of teaching.
- Full Text:
- Date Issued: 2012
Graphene quantum dots and their metallophthalocyanines nanoconjugates as novel photoluminescent nanosensors
- Authors: Achadu, Ojodomo John
- Date: 2018
- Subjects: Quantum dots , Graphene , Phthalocyanines , Nanoconjugates , Novel photoluminescent nanosensors , Metallophthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60719 , vital:27821
- Description: The fabrication and application of graphene quantum dots (GQDs)-based photoluminescent probes for the detection of analytes is presented. GQDs were functionalized with complexes such as metallophthalocyanines (MPcs), metal nanoparticles (Au@Ag NPs), 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl (TEMPO), maleimide and thymine for the sensing of target analytes such as ascorbic acid (AA), biothiols (cysteine, homocysteine and glutathione) and mercury ion (Hg²+). The design strategy and approach was based on the quenching of the fluorescence of the GQDs upon functionalization with the above-mentioned complexes, which could be restored in the presence of the target analytes (due to their specific interaction affinity with the complexes). For the detection of AA, GQDs were covalently and/or non-covalently conjugated to TEMPO-bearing complexes to form GQDs-4A-TEMPO and GQDs-TEMPO-MPc systems with nanomolar limits of detection. For the detection of biothiols, Au@Ag NPs and maleimide-bearing complexes (MPc), which have specific affinity to interact with biothiols, were deployed. Hg²+ detection involved the use of GQDs and/or MPcs with thiol and thymine groups, respectively. In addition, a smart sensing platform was designed for the dual detection of biothiols and Hg²+ using supramolecular hybrid of polyethyleneimine functionalized-GQDs and MPc-Au@Ag conjugate. The probe could detect, in a sequential manner, Hg²+ and biothiols with high sensitivity. Results obtained from the LODs of the probes showed that GQDs sensing performances could be enhanced in the presence of MPcs. The probes designed in this work were successfully deployed in the assays of the target analytes in real samples and the recoveries obtained confirmed the analytical applicability of the probes.
- Full Text:
- Date Issued: 2018
- Authors: Achadu, Ojodomo John
- Date: 2018
- Subjects: Quantum dots , Graphene , Phthalocyanines , Nanoconjugates , Novel photoluminescent nanosensors , Metallophthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60719 , vital:27821
- Description: The fabrication and application of graphene quantum dots (GQDs)-based photoluminescent probes for the detection of analytes is presented. GQDs were functionalized with complexes such as metallophthalocyanines (MPcs), metal nanoparticles (Au@Ag NPs), 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl (TEMPO), maleimide and thymine for the sensing of target analytes such as ascorbic acid (AA), biothiols (cysteine, homocysteine and glutathione) and mercury ion (Hg²+). The design strategy and approach was based on the quenching of the fluorescence of the GQDs upon functionalization with the above-mentioned complexes, which could be restored in the presence of the target analytes (due to their specific interaction affinity with the complexes). For the detection of AA, GQDs were covalently and/or non-covalently conjugated to TEMPO-bearing complexes to form GQDs-4A-TEMPO and GQDs-TEMPO-MPc systems with nanomolar limits of detection. For the detection of biothiols, Au@Ag NPs and maleimide-bearing complexes (MPc), which have specific affinity to interact with biothiols, were deployed. Hg²+ detection involved the use of GQDs and/or MPcs with thiol and thymine groups, respectively. In addition, a smart sensing platform was designed for the dual detection of biothiols and Hg²+ using supramolecular hybrid of polyethyleneimine functionalized-GQDs and MPc-Au@Ag conjugate. The probe could detect, in a sequential manner, Hg²+ and biothiols with high sensitivity. Results obtained from the LODs of the probes showed that GQDs sensing performances could be enhanced in the presence of MPcs. The probes designed in this work were successfully deployed in the assays of the target analytes in real samples and the recoveries obtained confirmed the analytical applicability of the probes.
- Full Text:
- Date Issued: 2018
The phenomenolgoical experience of posttraumatic growth in the context of a traumatic bereavement
- Authors: Acheson, Kerry
- Date: 2009 , 2013-07-15
- Subjects: Post-traumatic stress disorder -- Case studies Bereavement -- Psychological aspects Death -- Psychological aspects Phenomenological psychology Grief
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3102 , http://hdl.handle.net/10962/d1004456
- Description: The present study involves an exploration of the phenomenological expenence of posttraumatic growth in the context of a traumatic bereavement. An idiographic case study of a student who had witnessed her mother's death twelve years previously was conducted. Semi-structured interviews elicited data which was analysed using interpretative phenomenological analysis (IP A). Posttraumatic growth was found to have developed with regards to self-perception, relationships, and also in a broader spiritual and existential domain. The findings of this study shed light on the extant posttraumatic growth literature. In particular, findings were discussed in relation to the posttraumatic growth model as proposed by Calhoun and Tedeschi (2006). As posttraumatic growth is a relatively young concept, further research is needed in order to understand the meaning of reported growth more fully. While posttraumatic growth has been investigated in the context of bereavement, future research should distinguish more clearly between growth following traumatic and non-traumatic bereavement. Posttraumatic growth has received minimal empirical attention in South Africa, and therefore exploration of this area is suggested in the future. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2009
- Authors: Acheson, Kerry
- Date: 2009 , 2013-07-15
- Subjects: Post-traumatic stress disorder -- Case studies Bereavement -- Psychological aspects Death -- Psychological aspects Phenomenological psychology Grief
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3102 , http://hdl.handle.net/10962/d1004456
- Description: The present study involves an exploration of the phenomenological expenence of posttraumatic growth in the context of a traumatic bereavement. An idiographic case study of a student who had witnessed her mother's death twelve years previously was conducted. Semi-structured interviews elicited data which was analysed using interpretative phenomenological analysis (IP A). Posttraumatic growth was found to have developed with regards to self-perception, relationships, and also in a broader spiritual and existential domain. The findings of this study shed light on the extant posttraumatic growth literature. In particular, findings were discussed in relation to the posttraumatic growth model as proposed by Calhoun and Tedeschi (2006). As posttraumatic growth is a relatively young concept, further research is needed in order to understand the meaning of reported growth more fully. While posttraumatic growth has been investigated in the context of bereavement, future research should distinguish more clearly between growth following traumatic and non-traumatic bereavement. Posttraumatic growth has received minimal empirical attention in South Africa, and therefore exploration of this area is suggested in the future. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2009
Writing the aerial dancing body a preliminary choreological investigation of the aesthetics and kinetics of the aerial dancing body
- Authors: Acker, Shaun Albert
- Date: 2010
- Subjects: Dance -- 19th century Dance -- 20th century Dance -- 21st century Aerialists Movement, Aesthetics of Feminine beauty (Aesthetics) Movement notation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2129 , http://hdl.handle.net/10962/d1002361
- Description: This mini-thesis investigates some of the nineteenth century socio-cultural ideals that have structured a connection between virtuosic aerial skill and bodily aesthetics. It views the emergence of a style of aerial kineticism that is structured from the gender ideologies of the period. It investigates the continual recurrence of this nineteenth century style amongst contemporary aerial dance works and outlines the possible frictions between this Victorian style of kineticism and contemporary aerial explorations. From this observation, a possible catalyst may be observed with which to relocate and inspire a study of aerial kinetics sans the nineteenth century aesthetic component. This kinesiological catalyst may be viewed in conjunction with the theories of ground-based kinetic theorist, Rudolph Laban’s choreutic study of the body in space. Thus, it may be possible to suggest and introduce a possible practical dance scholarship for aerial dance. This mini-thesis includes an introductory choreological investigation that draws on and integrates the disciplines of kinesiology; choreutic theory; existing aerial kinetic technique; musicology; and the physical sciences.
- Full Text:
- Date Issued: 2010
- Authors: Acker, Shaun Albert
- Date: 2010
- Subjects: Dance -- 19th century Dance -- 20th century Dance -- 21st century Aerialists Movement, Aesthetics of Feminine beauty (Aesthetics) Movement notation
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2129 , http://hdl.handle.net/10962/d1002361
- Description: This mini-thesis investigates some of the nineteenth century socio-cultural ideals that have structured a connection between virtuosic aerial skill and bodily aesthetics. It views the emergence of a style of aerial kineticism that is structured from the gender ideologies of the period. It investigates the continual recurrence of this nineteenth century style amongst contemporary aerial dance works and outlines the possible frictions between this Victorian style of kineticism and contemporary aerial explorations. From this observation, a possible catalyst may be observed with which to relocate and inspire a study of aerial kinetics sans the nineteenth century aesthetic component. This kinesiological catalyst may be viewed in conjunction with the theories of ground-based kinetic theorist, Rudolph Laban’s choreutic study of the body in space. Thus, it may be possible to suggest and introduce a possible practical dance scholarship for aerial dance. This mini-thesis includes an introductory choreological investigation that draws on and integrates the disciplines of kinesiology; choreutic theory; existing aerial kinetic technique; musicology; and the physical sciences.
- Full Text:
- Date Issued: 2010
Building cultural capital through value-driven leadership: a case study in an international finance company
- Authors: Ackerman, Mariana
- Date: 2006
- Subjects: Financial institutions, International -- Namibia Case studies , Leadership -- Namibia Case studies , Corporate culture -- Namibia Case studies , Organizational change -- Namibia Case studies , Organizational effectiveness -- Namibia Case studies
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:2919 , http://hdl.handle.net/10962/d1002428 , Financial institutions, International -- Namibia Case studies , Leadership -- Namibia Case studies , Corporate culture -- Namibia Case studies , Organizational change -- Namibia Case studies , Organizational effectiveness -- Namibia Case studies
- Description: Today, organizations are placed under extreme pressure to adapt to the ever-increasing changes in their environments in order to survive. Research proves that corporate culture has the ability to either blunt or aid change. Past research conducted in Z-Nam, a subsidiary of an international finance company situated in Namibia, indicated that a divided culture resulted in limitations in their functioning, including their adaptability. Pressure was placed on Z-Nam by its majority shareholder to internalise a set of core values into its daily functioning in order to build a strong adaptable culture. This objective called for values-driven leadership. The four core values identified by Head Office were integrity, respect, accountability and pushing beyond boundaries. In becoming more values-driven, values theory posits that Z-Nam will build its cultural capital and so reap the benefits of higher performance, talent retention and adaptability. In this way Z-Nam will be able to combat the weaknesses in its current culture. Leadership adaptability and the capacity to lead change were seen to distinguish cultural changes that succeed from those that do not. Principles inherent in the field of OD were also considered, as they are seen to assist in the effective management of change. The methodology involved a purposive sample being drawn that included the top leadership team and internal OD consultant. Semi-structured interviews were conducted and thematic analysis employed in analysing the resultant data with three main aims in mind. Firstly, to assess Z-Nam's top management's perception of the current set of values being lived in the organization, to establish their level of support for the desired set of values proposed by Head Office and lastly to establish whether the leadership team is ready to promote the adoption of a new set of core values. Through comparing the themes that emerged from the data with literature on OD, values, culture and change, the researcher was able to make inferences as to the leadership's readiness and capacity to successfully lead cultural change. These findings were substantiated with secondary data from previous research activities. It was found that Z-Nam was not utilising its culture as an asset and that several barriers existed to adopting and implementing the desired values. It was concluded that Z-Nam will not be able to successfully embark on cultural change until its leadership recognises the importance of culture and their personal responsibility in bringing about the desired change, adequately assimilates information from past research and comes to a consensus as to the necessary accommodations that need to be made.
- Full Text:
- Date Issued: 2006
- Authors: Ackerman, Mariana
- Date: 2006
- Subjects: Financial institutions, International -- Namibia Case studies , Leadership -- Namibia Case studies , Corporate culture -- Namibia Case studies , Organizational change -- Namibia Case studies , Organizational effectiveness -- Namibia Case studies
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:2919 , http://hdl.handle.net/10962/d1002428 , Financial institutions, International -- Namibia Case studies , Leadership -- Namibia Case studies , Corporate culture -- Namibia Case studies , Organizational change -- Namibia Case studies , Organizational effectiveness -- Namibia Case studies
- Description: Today, organizations are placed under extreme pressure to adapt to the ever-increasing changes in their environments in order to survive. Research proves that corporate culture has the ability to either blunt or aid change. Past research conducted in Z-Nam, a subsidiary of an international finance company situated in Namibia, indicated that a divided culture resulted in limitations in their functioning, including their adaptability. Pressure was placed on Z-Nam by its majority shareholder to internalise a set of core values into its daily functioning in order to build a strong adaptable culture. This objective called for values-driven leadership. The four core values identified by Head Office were integrity, respect, accountability and pushing beyond boundaries. In becoming more values-driven, values theory posits that Z-Nam will build its cultural capital and so reap the benefits of higher performance, talent retention and adaptability. In this way Z-Nam will be able to combat the weaknesses in its current culture. Leadership adaptability and the capacity to lead change were seen to distinguish cultural changes that succeed from those that do not. Principles inherent in the field of OD were also considered, as they are seen to assist in the effective management of change. The methodology involved a purposive sample being drawn that included the top leadership team and internal OD consultant. Semi-structured interviews were conducted and thematic analysis employed in analysing the resultant data with three main aims in mind. Firstly, to assess Z-Nam's top management's perception of the current set of values being lived in the organization, to establish their level of support for the desired set of values proposed by Head Office and lastly to establish whether the leadership team is ready to promote the adoption of a new set of core values. Through comparing the themes that emerged from the data with literature on OD, values, culture and change, the researcher was able to make inferences as to the leadership's readiness and capacity to successfully lead cultural change. These findings were substantiated with secondary data from previous research activities. It was found that Z-Nam was not utilising its culture as an asset and that several barriers existed to adopting and implementing the desired values. It was concluded that Z-Nam will not be able to successfully embark on cultural change until its leadership recognises the importance of culture and their personal responsibility in bringing about the desired change, adequately assimilates information from past research and comes to a consensus as to the necessary accommodations that need to be made.
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- Date Issued: 2006