"I felt that I deserved it" : an Investigation into HIV-related PTSD, traumatic life events, and the personal experiences of living with HIV : a mixed-method study
- Authors: Boulind, Melissa Jane
- Date: 2014
- Subjects: Post-traumatic stress disorder -- Psychological aspects -- Research -- South Africa -- Kwazulu HIV infections -- Psychological aspects -- Research -- South Africa -- Kwazulu HIV-positive persons -- South Africa -- Kwazulu -- Interviews Psychic trauma -- Research Stress (Psychology) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3211 , http://hdl.handle.net/10962/d1012172
- Description: There appears to be a growing body of literature focusing on PTSD and HIV-related PTSD (the diagnosis of HIV being the significant traumatic event) amongst HIV-positive samples, but only a few African studies that attempt to estimate the prevalence of PTSD amongst HIV-positive people, and even fewer that attempt to estimate the prevalence of HIV-related PTSD. The systemic review presented in this study is currently fully inclusive and is the most up-to-date available. Estimates of the prevalence of PTSD and HIV-related PTSD in South Africa range from 0.7 to 54.1% and, 4.2 to 40% respectively. The current cross-sectional study made use of a mixed-method approach to investigate traumatic life events, PTSD and HIV-related PTSD within a primary health-care centre in KwaZulu-Natal. The quantitative sample consisted of 159 adults (18-50 years) who were compliant on ARV medication. Using the CIDI-PTSD module, the adapted CIDI-PTSD module for HIV, and IES-R, findings indicated that 62% had reported some kind of traumatic event in their lifetime, with 29.6% of participants meeting the criteria for lifetime PTSD, and 40.9% meeting the criteria for lifetime HIV-related PTSD. Altogether, 57.9% of individuals met the criteria for some form of PTSD (either regular PTSD or HIV-related PTSD), and 12.6% met the criteria for both PTSD and HIV-related PTSD. Of the different categories of traumatic events, interpersonal violence has the highest rate of PTSD, followed by a diagnosis of and living with HIV, and then disaster. Furthermore, the IES-R was compared for its usefulness as a screening measure for PTSD against both the CIDI, but results suggest that it is an inferior screening measure to the PDS. The qualitative study consisted of six participants who were examined using IPA methodology informed by the Ehlers and Clark (2000) Model of trauma. Their experiences revealed experiences of stigma, a number of negative appraisals, negative emotions and coping behaviours. Some of the latter might serve as compensatory mechanisms to avoid negative judgements. Hypervigilance seems to be a feature of ARV-compliance that might confer added vulnerability to PTSD and other anxiety disorders.
- Full Text:
- Authors: Boulind, Melissa Jane
- Date: 2014
- Subjects: Post-traumatic stress disorder -- Psychological aspects -- Research -- South Africa -- Kwazulu HIV infections -- Psychological aspects -- Research -- South Africa -- Kwazulu HIV-positive persons -- South Africa -- Kwazulu -- Interviews Psychic trauma -- Research Stress (Psychology) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3211 , http://hdl.handle.net/10962/d1012172
- Description: There appears to be a growing body of literature focusing on PTSD and HIV-related PTSD (the diagnosis of HIV being the significant traumatic event) amongst HIV-positive samples, but only a few African studies that attempt to estimate the prevalence of PTSD amongst HIV-positive people, and even fewer that attempt to estimate the prevalence of HIV-related PTSD. The systemic review presented in this study is currently fully inclusive and is the most up-to-date available. Estimates of the prevalence of PTSD and HIV-related PTSD in South Africa range from 0.7 to 54.1% and, 4.2 to 40% respectively. The current cross-sectional study made use of a mixed-method approach to investigate traumatic life events, PTSD and HIV-related PTSD within a primary health-care centre in KwaZulu-Natal. The quantitative sample consisted of 159 adults (18-50 years) who were compliant on ARV medication. Using the CIDI-PTSD module, the adapted CIDI-PTSD module for HIV, and IES-R, findings indicated that 62% had reported some kind of traumatic event in their lifetime, with 29.6% of participants meeting the criteria for lifetime PTSD, and 40.9% meeting the criteria for lifetime HIV-related PTSD. Altogether, 57.9% of individuals met the criteria for some form of PTSD (either regular PTSD or HIV-related PTSD), and 12.6% met the criteria for both PTSD and HIV-related PTSD. Of the different categories of traumatic events, interpersonal violence has the highest rate of PTSD, followed by a diagnosis of and living with HIV, and then disaster. Furthermore, the IES-R was compared for its usefulness as a screening measure for PTSD against both the CIDI, but results suggest that it is an inferior screening measure to the PDS. The qualitative study consisted of six participants who were examined using IPA methodology informed by the Ehlers and Clark (2000) Model of trauma. Their experiences revealed experiences of stigma, a number of negative appraisals, negative emotions and coping behaviours. Some of the latter might serve as compensatory mechanisms to avoid negative judgements. Hypervigilance seems to be a feature of ARV-compliance that might confer added vulnerability to PTSD and other anxiety disorders.
- Full Text:
(Re-)inventing our selves/ourselves : identity and community in contemporary South African short fiction cycles.
- Authors: Marais, Susan Jacqueline
- Date: 2014
- Subjects: South African fiction (English) -- History and criticism , Matlou, Joël -- Criticism and interpretation , Magona, Sindiwe -- Criticism and interpretation , Vladislavić, Ivan, 1957- -- Criticism and interpretation , Wicomb, Zoë -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2326 , http://hdl.handle.net/10962/d1016357
- Description: In this study I focus on a number of collections of short fiction by the South African writers Joël Matlou, Sindiwe Magona, Zoë Wicomb and Ivan Vladislavić, all of which evince certain of the characteristics of short story cycles or sequences. In other words, they display what Forrest L. Ingram describes as “a double tendency of asserting the individuality of [their] components on the one hand and of highlighting, on the other, the bonds of unity which make the many into a single whole”. The cycle form, thus defined, is characterised by a paradoxical yet productive and frequently unresolved tension between “the individuality of each of the stories and the necessities of the larger unit”, between “the one and the many”, and between cohesion and fragmentation. It is this “dynamic structure of connection and disconnection” which singularly equips the genre to represent the interrelationship of singular and collective identities, or the “coherent multiplicity of community”. Ingram, for example, asserts that “Numerous and varied connective strands draw the co-protagonists of any story cycle into a single community. … However this community may be achieved, it usually can be said to constitute the central character of a cycle”. Not unsurprisingly, then, in its dominant manifestations over much of the twentieth century the short story cycle demonstrated a marked inclination towards regionalism and the depiction of localised enclaves, and this tendency towards “place-based short story cycles” in which topographical unity is a conspicuous feature was as pronounced in South Africa as elsewhere. However, the specific collections which are my concern here increasingly employ innovative and self-reflexive narrative strategies that unsettle generic expectations and interrogate the notions of regionalism and community conventionally associated with the short story cycle. My investigation seeks to explain this shift in emphasis, and its particular significance within the South African context.
- Full Text:
- Authors: Marais, Susan Jacqueline
- Date: 2014
- Subjects: South African fiction (English) -- History and criticism , Matlou, Joël -- Criticism and interpretation , Magona, Sindiwe -- Criticism and interpretation , Vladislavić, Ivan, 1957- -- Criticism and interpretation , Wicomb, Zoë -- Criticism and interpretation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2326 , http://hdl.handle.net/10962/d1016357
- Description: In this study I focus on a number of collections of short fiction by the South African writers Joël Matlou, Sindiwe Magona, Zoë Wicomb and Ivan Vladislavić, all of which evince certain of the characteristics of short story cycles or sequences. In other words, they display what Forrest L. Ingram describes as “a double tendency of asserting the individuality of [their] components on the one hand and of highlighting, on the other, the bonds of unity which make the many into a single whole”. The cycle form, thus defined, is characterised by a paradoxical yet productive and frequently unresolved tension between “the individuality of each of the stories and the necessities of the larger unit”, between “the one and the many”, and between cohesion and fragmentation. It is this “dynamic structure of connection and disconnection” which singularly equips the genre to represent the interrelationship of singular and collective identities, or the “coherent multiplicity of community”. Ingram, for example, asserts that “Numerous and varied connective strands draw the co-protagonists of any story cycle into a single community. … However this community may be achieved, it usually can be said to constitute the central character of a cycle”. Not unsurprisingly, then, in its dominant manifestations over much of the twentieth century the short story cycle demonstrated a marked inclination towards regionalism and the depiction of localised enclaves, and this tendency towards “place-based short story cycles” in which topographical unity is a conspicuous feature was as pronounced in South Africa as elsewhere. However, the specific collections which are my concern here increasingly employ innovative and self-reflexive narrative strategies that unsettle generic expectations and interrogate the notions of regionalism and community conventionally associated with the short story cycle. My investigation seeks to explain this shift in emphasis, and its particular significance within the South African context.
- Full Text:
A case study of a pre-service mathematics education course to grow and develop proficient teaching in mathematics in the intermediate phase
- Authors: Lee, Amanda Jane
- Date: 2014
- Subjects: Mathematics -- Study and teaching -- South Africa , Mathematics teachers -- Training of -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2004 , http://hdl.handle.net/10962/d1015664
- Description: This research study investigated the ways in which a mathematics module, informed by an enactivist philosophy, enabled pre-service teachers to unpack the reality of their teaching practice in terms of proficient teaching. Given the generally poor mathematics results in South Africa it is not enough for teachers to be merely proficient in Mathematics. They also need to be in a position to explain important mathematical concepts to children in a manner that will encourage and develop an understanding of the basic mathematical concepts. It was my intention with this study to determine whether a mathematics education module, that embraced the underlying themes of enactivism as part of its teaching pedagogy, could have the potential to develop and increase the skills of pre-service teachers’ teaching for proficiency in Mathematics. The mathematics module was underpinned by five themes of enactivism namely: autonomy, embodiment, emergence, sense-making and experience and was designed to supplement the pre-service teachers’ basic skills in Mathematics in the Intermediate Phase. This mathematics module was offered to fourth year pre-service teachers completing a B.Ed. in the Foundation Phase at a private institute specialising in the training of teachers. The theoretical framework was informed by enactivism and how the themes of enactivism could be used as a vehicle to develop teaching proficiency. The study was qualitative in nature and situated within an interpretivist paradigm. The specific perspectives of interpretivism that were used were hermeneutics, phenomenology and reflexivity. The research design was a case study that contained elements of action research and encompassed three phases of data collection. The first phase focused on the pre-service teachers’ approach to teaching Mathematics and what this brought forth in terms of the reality of their teaching practice and the problems they encountered. The second phase undertook to determine what growth and development of teaching proficiency in Mathematics had emerged over the research period. The final phase was undertaken after the pre-service teachers had graduated and were employed as full time teachers in the Intermediate Phase. The analytical framework and lens through which the data was analysed was that of Kilpatrick, Swafford and Findell’s (2001) strands of mathematical proficiency. The argument that I present is that the themes of enactivism did contribute to the growth of the pre-service teachers’ teaching for mathematical proficiency. The themes of embodiment and experience were major contributions in revealing that this was a reality for the pre-service teachers from a practical perspective and was what they would be able to take away with them. However the theme of emergence stood out as the principle that generated the most awareness and growth and which, in turn, affected the participants’ autonomy.
- Full Text:
- Authors: Lee, Amanda Jane
- Date: 2014
- Subjects: Mathematics -- Study and teaching -- South Africa , Mathematics teachers -- Training of -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2004 , http://hdl.handle.net/10962/d1015664
- Description: This research study investigated the ways in which a mathematics module, informed by an enactivist philosophy, enabled pre-service teachers to unpack the reality of their teaching practice in terms of proficient teaching. Given the generally poor mathematics results in South Africa it is not enough for teachers to be merely proficient in Mathematics. They also need to be in a position to explain important mathematical concepts to children in a manner that will encourage and develop an understanding of the basic mathematical concepts. It was my intention with this study to determine whether a mathematics education module, that embraced the underlying themes of enactivism as part of its teaching pedagogy, could have the potential to develop and increase the skills of pre-service teachers’ teaching for proficiency in Mathematics. The mathematics module was underpinned by five themes of enactivism namely: autonomy, embodiment, emergence, sense-making and experience and was designed to supplement the pre-service teachers’ basic skills in Mathematics in the Intermediate Phase. This mathematics module was offered to fourth year pre-service teachers completing a B.Ed. in the Foundation Phase at a private institute specialising in the training of teachers. The theoretical framework was informed by enactivism and how the themes of enactivism could be used as a vehicle to develop teaching proficiency. The study was qualitative in nature and situated within an interpretivist paradigm. The specific perspectives of interpretivism that were used were hermeneutics, phenomenology and reflexivity. The research design was a case study that contained elements of action research and encompassed three phases of data collection. The first phase focused on the pre-service teachers’ approach to teaching Mathematics and what this brought forth in terms of the reality of their teaching practice and the problems they encountered. The second phase undertook to determine what growth and development of teaching proficiency in Mathematics had emerged over the research period. The final phase was undertaken after the pre-service teachers had graduated and were employed as full time teachers in the Intermediate Phase. The analytical framework and lens through which the data was analysed was that of Kilpatrick, Swafford and Findell’s (2001) strands of mathematical proficiency. The argument that I present is that the themes of enactivism did contribute to the growth of the pre-service teachers’ teaching for mathematical proficiency. The themes of embodiment and experience were major contributions in revealing that this was a reality for the pre-service teachers from a practical perspective and was what they would be able to take away with them. However the theme of emergence stood out as the principle that generated the most awareness and growth and which, in turn, affected the participants’ autonomy.
- Full Text:
A formalised ontology for network attack classification
- Authors: Van Heerden, Renier Pelser
- Date: 2014
- Subjects: Computer networks -- Security measures Computer security Computer crimes -- Investigation Computer crimes -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4691 , http://hdl.handle.net/10962/d1011603
- Description: One of the most popular attack vectors against computers are their network connections. Attacks on computers through their networks are commonplace and have various levels of complexity. This research formally describes network-based computer attacks in the form of a story, formally and within an ontology. The ontology categorises network attacks where attack scenarios are the focal class. This class consists of: Denial-of- Service, Industrial Espionage, Web Defacement, Unauthorised Data Access, Financial Theft, Industrial Sabotage, Cyber-Warfare, Resource Theft, System Compromise, and Runaway Malware. This ontology was developed by building a taxonomy and a temporal network attack model. Network attack instances (also know as individuals) are classified according to their respective attack scenarios, with the use of an automated reasoner within the ontology. The automated reasoner deductions are verified formally; and via the automated reasoner, a relaxed set of scenarios is determined, which is relevant in a near real-time environment. A prototype system (called Aeneas) was developed to classify network-based attacks. Aeneas integrates the sensors into a detection system that can classify network attacks in a near real-time environment. To verify the ontology and the prototype Aeneas, a virtual test bed was developed in which network-based attacks were generated to verify the detection system. Aeneas was able to detect incoming attacks and classify them according to their scenario. The novel part of this research is the attack scenarios that are described in the form of a story, as well as formally and in an ontology. The ontology is used in a novel way to determine to which class attack instances belong and how the network attack ontology is affected in a near real-time environment.
- Full Text:
- Authors: Van Heerden, Renier Pelser
- Date: 2014
- Subjects: Computer networks -- Security measures Computer security Computer crimes -- Investigation Computer crimes -- Prevention
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4691 , http://hdl.handle.net/10962/d1011603
- Description: One of the most popular attack vectors against computers are their network connections. Attacks on computers through their networks are commonplace and have various levels of complexity. This research formally describes network-based computer attacks in the form of a story, formally and within an ontology. The ontology categorises network attacks where attack scenarios are the focal class. This class consists of: Denial-of- Service, Industrial Espionage, Web Defacement, Unauthorised Data Access, Financial Theft, Industrial Sabotage, Cyber-Warfare, Resource Theft, System Compromise, and Runaway Malware. This ontology was developed by building a taxonomy and a temporal network attack model. Network attack instances (also know as individuals) are classified according to their respective attack scenarios, with the use of an automated reasoner within the ontology. The automated reasoner deductions are verified formally; and via the automated reasoner, a relaxed set of scenarios is determined, which is relevant in a near real-time environment. A prototype system (called Aeneas) was developed to classify network-based attacks. Aeneas integrates the sensors into a detection system that can classify network attacks in a near real-time environment. To verify the ontology and the prototype Aeneas, a virtual test bed was developed in which network-based attacks were generated to verify the detection system. Aeneas was able to detect incoming attacks and classify them according to their scenario. The novel part of this research is the attack scenarios that are described in the form of a story, as well as formally and in an ontology. The ontology is used in a novel way to determine to which class attack instances belong and how the network attack ontology is affected in a near real-time environment.
- Full Text:
A lignocellulolytic enzyme system for fruit waste degradation : commercial enzyme mixture synergy and bioreactor design
- Authors: Gama, Repson
- Date: 2014
- Subjects: Enzymes -- Biotechnology , Enzymes -- Industrial applications , Lignocellulose -- Biodegradation , Biomass energy , Biomass conversion , Biochemical engineering , Agricultural wastes as fuel
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4114 , http://hdl.handle.net/10962/d1013073
- Description: Studies into sources of alternative liquid transport fuel energy have identified agro-industrial wastes, which are lignocellulosic in nature, as a potential feedstock for biofuel production against the background of depleting nonrenewable fossil fuels. In South Africa, large quantities of apple and other fruit wastes, called pomace, are generated from fruit and juice industries. Apple pomace is a rich source of cellulose, pectin and hemicellulose, making it a potential target for utilisation as a lignocellulosic feedstock for biofuel and biorefinery chemical production. Lignocellulosic biomass is recalcitrant in nature and therefore its degradation requires the synergistic action of a number of enzymes such as cellulases, hemicellulases, pectinases and ligninases. Commercial enzyme cocktails, containing some of these enzymes, are available and can be used for apple pomace degradation. In this study, the degradation of apple pomace using commercial enzyme cocktails was investigated. The main focus was the optimisation of the release of sugar monomers that could potentially be used for biofuel and biorefinery chemical production. There is no or little information reported in literature on the enzymatic degradation of fruit waste using commercial enzyme mixtures. This study first focused on the characterisation of the substrate (apple pomace) and the commercial enzyme cocktails. Apple pomace was found to contain mainly glucose, galacturonic acid, arabinose, galactose, lignin and low amounts of xylose and fructose. Three commercial enzyme cocktails were initially selected: Biocip Membrane, Viscozyme L (from Aspergillus aculeatus) and Celluclast 1.5L (a Trichoderma reesei ATCC 26921 cellulase preparation). The selection of the enzymes was based on activities declared by the manufacturers, cost and local availability. The enzymes were screened based on their synergistic cooperation in the degradation of apple pomace and the main enzymes present in each cocktail. Viscozyme L and Celluclast 1.5L, in a 50:50 ratio, resulted in the best degree of synergy (1.6) compared to any other combination. The enzyme ratios were determined on Viscozyme L and Celluclast 1.5L based on the protein ratio. Enzyme activity was determined as glucose equivalents using the dinitrosalicylic acid (DNS) method. Sugar monomers were determined using Megazyme assay kits. There is limited information available on the enzymes present in the commercial enzyme cocktails. Therefore, the main enzymes present in Viscozyme L and Celluclast 1.5L were identified using different substrates, each targeted for a specific enzyme and activity. Characterisation of the enzyme mixtures revealed a large number of enzymes required for apple pomace degradation and these included cellulases, pectinases, xylanases, arabinases and mannanases in different proportions. Viscozyme L contained mainly pectinases and hemicellulases, while Celluclast 1.5L displayed largely cellulase and xylanase activity, hence the high degree of synergy reported. The temperature optimum was 50ºC for both enzyme mixtures and pH optima were observed at pH 5.0 and pH 3.0 for Viscozyme L and Celluclast 1.5L, respectively. At 37ºC and pH 5.0, the enzymes retained more that 90% activity after 15 days of incubation, allowing the enzymes to be used together with less energy input. The enzymes were further characterised by determining the effect of various compounds, such as alcohols, sugars, phenolic compounds and metal ions at various concentrations on the activity of the enzymes during apple pomace hydrolysis. Apart from lignin, which had almost no effect on enzyme activity, all the compounds caused inhibition of the enzymes to varying degrees. The most inhibitory compounds were some organic acids and metal ions, as well as cellobiose and xylobiose. Using the best ratio for Viscozyme L and Celluclast 1.5L (50:50) for the hydrolysis of apple pomace, it was observed that synergy was highest at the initial stages of hydrolysis and decreased over time, though the sugar concentration increased. The type of synergy for optimal apple pomace hydrolysis was found to be simultaneous. There was no synergy observed between Viscozyme L and Celluclast 1.5L with ligninases - laccase, lignin peroxidase and manganese peroxidase. Hydrolysing apple pomace with ligninases prior to addition of Viscozyme L and Celluclast 1.5L did not improve degradation of the substrate. Immobilisation of the enzyme mixtures on different supports was performed with the aim of increasing stability and enabling reuse of the enzymes. Immobilisation methods were selected based on the chemical properties of the supports, availability, cost and applicability on heterogeneous and insoluble substrate like apple pomace. These methods included crosslinked enzyme aggregates (CLEAs), immobilisation on various supports such as nylon mesh, nylon beads, sodium alginate beads, chitin and silica gel beads. The immobilisation strategies were unsuccessful, mainly due to the low percentage of immobilisation of the enzyme on the matrix and loss of activity of the immobilised enzyme. Free enzymes were therefore used for the remainder of the study. Hydrolysis conditions for apple pomace degradation were optimised using different temperatures and buffer systems in 1 L volumes mixed with compressed air. Hydrolysis at room temperature, using an unbuffered system, gave a better performance as compared to a buffered system. Reactors operated in batch mode performed better (4.2 g/L (75% yield) glucose and 16.8 g/L (75%) reducing sugar) than fed-batch reactors (3.2 g/L (66%) glucose and 14.6 g/L (72.7% yield) reducing sugar) over 100 h using Viscozyme L and Celluclast 1.5L. Supplementation of β- glucosidase activity in Viscozyme L and Celluclast 1.5L with Novozyme 188 resulted in a doubling of the amount of glucose released. The main products released from apple pomace hydrolysis were galacturonic acid, glucose and arabinose and low amounts of galactose and xylose. These products are potential raw materials for biofuel and biorefinery chemical production. An artificial neural network (ANN) model was successfully developed and used for predicting the optimum conditions for apple pomace hydrolysis using Celluclast 1.5L, Viscozyme L and Novozyme 188. Four main conditions that affect apple pomace hydrolysis were selected, namely temperature, initial pH, enzyme loading and substrate loading, which were taken as inputs. The glucose and reducing sugars released as a result of each treatment and their combinations were taken as outputs for 1–100 h. An ANN with 20, 20 and 6 neurons in the first, second and third hidden layers, respectively, was constructed. The performance and predictive ability of the ANN was good, with a R² of 0.99 and a small mean square error (MSE). New data was successfully predicted and simulated. Optimal hydrolysis conditions predicted by ANN for apple pomace hydrolysis were at 30% substrate (wet w/v) and an enzyme loading of 0.5 mg/g and 0.2 mg/mL of substrate for glucose and reducing sugar, respectively, giving sugar concentrations of 6.5 mg/mL and 28.9 mg/mL for glucose and reducing sugar, respectively. ANN showed that enzyme and substrate loadings were the most important factors for the hydrolysis of apple pomace.
- Full Text:
- Authors: Gama, Repson
- Date: 2014
- Subjects: Enzymes -- Biotechnology , Enzymes -- Industrial applications , Lignocellulose -- Biodegradation , Biomass energy , Biomass conversion , Biochemical engineering , Agricultural wastes as fuel
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4114 , http://hdl.handle.net/10962/d1013073
- Description: Studies into sources of alternative liquid transport fuel energy have identified agro-industrial wastes, which are lignocellulosic in nature, as a potential feedstock for biofuel production against the background of depleting nonrenewable fossil fuels. In South Africa, large quantities of apple and other fruit wastes, called pomace, are generated from fruit and juice industries. Apple pomace is a rich source of cellulose, pectin and hemicellulose, making it a potential target for utilisation as a lignocellulosic feedstock for biofuel and biorefinery chemical production. Lignocellulosic biomass is recalcitrant in nature and therefore its degradation requires the synergistic action of a number of enzymes such as cellulases, hemicellulases, pectinases and ligninases. Commercial enzyme cocktails, containing some of these enzymes, are available and can be used for apple pomace degradation. In this study, the degradation of apple pomace using commercial enzyme cocktails was investigated. The main focus was the optimisation of the release of sugar monomers that could potentially be used for biofuel and biorefinery chemical production. There is no or little information reported in literature on the enzymatic degradation of fruit waste using commercial enzyme mixtures. This study first focused on the characterisation of the substrate (apple pomace) and the commercial enzyme cocktails. Apple pomace was found to contain mainly glucose, galacturonic acid, arabinose, galactose, lignin and low amounts of xylose and fructose. Three commercial enzyme cocktails were initially selected: Biocip Membrane, Viscozyme L (from Aspergillus aculeatus) and Celluclast 1.5L (a Trichoderma reesei ATCC 26921 cellulase preparation). The selection of the enzymes was based on activities declared by the manufacturers, cost and local availability. The enzymes were screened based on their synergistic cooperation in the degradation of apple pomace and the main enzymes present in each cocktail. Viscozyme L and Celluclast 1.5L, in a 50:50 ratio, resulted in the best degree of synergy (1.6) compared to any other combination. The enzyme ratios were determined on Viscozyme L and Celluclast 1.5L based on the protein ratio. Enzyme activity was determined as glucose equivalents using the dinitrosalicylic acid (DNS) method. Sugar monomers were determined using Megazyme assay kits. There is limited information available on the enzymes present in the commercial enzyme cocktails. Therefore, the main enzymes present in Viscozyme L and Celluclast 1.5L were identified using different substrates, each targeted for a specific enzyme and activity. Characterisation of the enzyme mixtures revealed a large number of enzymes required for apple pomace degradation and these included cellulases, pectinases, xylanases, arabinases and mannanases in different proportions. Viscozyme L contained mainly pectinases and hemicellulases, while Celluclast 1.5L displayed largely cellulase and xylanase activity, hence the high degree of synergy reported. The temperature optimum was 50ºC for both enzyme mixtures and pH optima were observed at pH 5.0 and pH 3.0 for Viscozyme L and Celluclast 1.5L, respectively. At 37ºC and pH 5.0, the enzymes retained more that 90% activity after 15 days of incubation, allowing the enzymes to be used together with less energy input. The enzymes were further characterised by determining the effect of various compounds, such as alcohols, sugars, phenolic compounds and metal ions at various concentrations on the activity of the enzymes during apple pomace hydrolysis. Apart from lignin, which had almost no effect on enzyme activity, all the compounds caused inhibition of the enzymes to varying degrees. The most inhibitory compounds were some organic acids and metal ions, as well as cellobiose and xylobiose. Using the best ratio for Viscozyme L and Celluclast 1.5L (50:50) for the hydrolysis of apple pomace, it was observed that synergy was highest at the initial stages of hydrolysis and decreased over time, though the sugar concentration increased. The type of synergy for optimal apple pomace hydrolysis was found to be simultaneous. There was no synergy observed between Viscozyme L and Celluclast 1.5L with ligninases - laccase, lignin peroxidase and manganese peroxidase. Hydrolysing apple pomace with ligninases prior to addition of Viscozyme L and Celluclast 1.5L did not improve degradation of the substrate. Immobilisation of the enzyme mixtures on different supports was performed with the aim of increasing stability and enabling reuse of the enzymes. Immobilisation methods were selected based on the chemical properties of the supports, availability, cost and applicability on heterogeneous and insoluble substrate like apple pomace. These methods included crosslinked enzyme aggregates (CLEAs), immobilisation on various supports such as nylon mesh, nylon beads, sodium alginate beads, chitin and silica gel beads. The immobilisation strategies were unsuccessful, mainly due to the low percentage of immobilisation of the enzyme on the matrix and loss of activity of the immobilised enzyme. Free enzymes were therefore used for the remainder of the study. Hydrolysis conditions for apple pomace degradation were optimised using different temperatures and buffer systems in 1 L volumes mixed with compressed air. Hydrolysis at room temperature, using an unbuffered system, gave a better performance as compared to a buffered system. Reactors operated in batch mode performed better (4.2 g/L (75% yield) glucose and 16.8 g/L (75%) reducing sugar) than fed-batch reactors (3.2 g/L (66%) glucose and 14.6 g/L (72.7% yield) reducing sugar) over 100 h using Viscozyme L and Celluclast 1.5L. Supplementation of β- glucosidase activity in Viscozyme L and Celluclast 1.5L with Novozyme 188 resulted in a doubling of the amount of glucose released. The main products released from apple pomace hydrolysis were galacturonic acid, glucose and arabinose and low amounts of galactose and xylose. These products are potential raw materials for biofuel and biorefinery chemical production. An artificial neural network (ANN) model was successfully developed and used for predicting the optimum conditions for apple pomace hydrolysis using Celluclast 1.5L, Viscozyme L and Novozyme 188. Four main conditions that affect apple pomace hydrolysis were selected, namely temperature, initial pH, enzyme loading and substrate loading, which were taken as inputs. The glucose and reducing sugars released as a result of each treatment and their combinations were taken as outputs for 1–100 h. An ANN with 20, 20 and 6 neurons in the first, second and third hidden layers, respectively, was constructed. The performance and predictive ability of the ANN was good, with a R² of 0.99 and a small mean square error (MSE). New data was successfully predicted and simulated. Optimal hydrolysis conditions predicted by ANN for apple pomace hydrolysis were at 30% substrate (wet w/v) and an enzyme loading of 0.5 mg/g and 0.2 mg/mL of substrate for glucose and reducing sugar, respectively, giving sugar concentrations of 6.5 mg/mL and 28.9 mg/mL for glucose and reducing sugar, respectively. ANN showed that enzyme and substrate loadings were the most important factors for the hydrolysis of apple pomace.
- Full Text:
A sociological analysis of the provision of extended studies as a means of addressing transformation at a historically white university
- Authors: Tanyanyiwa, Precious
- Date: 2014
- Subjects: Rhodes University , Articulation (Education) , Articulation (Education) -- South Africa -- Grahamstown , Educational equalization -- South Africa -- Grahamstown , Discrimination in education -- South Africa -- Grahamstown , Education, Higher -- South Africa -- Grahamstown , Bourdieu, Pierre, 1930-2002 , Sen, Amartya, 1933-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3370 , http://hdl.handle.net/10962/d1012655
- Description: Foundation provisioning has a long history in South Africa, and is central to the transformation agenda, particularly the broadening of successful participation in higher education (HE). As access initiatives underpinned by various conceptualisations, foundation programmes evolved from peripheral, to semi-integrated and finally fully integrated curricular models in the form of current Extended Studies Programmes (ESPs). Underpinning the provision of Extended Studies is the acknowledgment that students who enter institutions are essentially ill equipped to cope with the demands of higher education studies, “leaving institutions themselves free of the responsibility of student failure” (Akoojee & Nkomo, 2007:391). This under-preparedness has been attributed to the ‘articulation gap’ between secondary and higher education, which in turn contributes to low retention and graduation rates (CHE, 2013:17). Situated within an overarching commitment to access and success, the Extended Studies Programme attempts to systematically address the ‘articulation gap’. This study evaluated the extent to which the Rhodes University Humanities Extended Studies Programme is achieving its objectives from a transformation perspective, specifically the broadening of successful participation in higher education. The majority of previous works on the evaluation of foundation programmes focused on measurable dimensions of student access and success – that is retention and graduation rates. This thesis considered both the measurable outcomes of the programme as well as the actual teaching and learning process. Given the shifts that have taken place in foundation provisioning, the evaluation of the current model of foundation provisioning necessitated their location in history. Therefore, the evaluation of the Rhodes University Humanities Extended Studies Programme was undertaken in view of the shifts, achievements, challenges and critics of its predecessor programmes. Specifically, the following dimensions were considered in the evaluation of the programme: i) assumptions underpinning the design and purpose of the programme, ii) teaching and learning practices in the programme, iii) student and staff perceptions of the programme, iv) students’ experiences of the programme, v) the validity of the programme in the broader institution, and vi) the measurable outcomes of the programme − that is retention and graduation rates of students enrolled in the programme. The triangulation of qualitative data collection techniques provided access into the different layers of institutional relations, processes and structures, which not only affect teaching and learning in the programme, but also determine students’ engagement with different academic and social aspects of the broader university. The theoretical insights of Pierre Bourdieu and Amartya Sen were integrated in order to provide analytical tools for both understanding the causes of inequalities in higher education, and evaluating institutional processes and structures that perpetuate or transform inequalities. Whilst Bourdieu’s social reproduction thesis exposed the ways in which social structures shape educational processes and outcomes, Sen’s capability approach provided tools for evaluating both institutional arrangements and individual capabilities – that is, the freedom to achieve desired educational outcomes (Sen, 1992:48).
- Full Text:
- Authors: Tanyanyiwa, Precious
- Date: 2014
- Subjects: Rhodes University , Articulation (Education) , Articulation (Education) -- South Africa -- Grahamstown , Educational equalization -- South Africa -- Grahamstown , Discrimination in education -- South Africa -- Grahamstown , Education, Higher -- South Africa -- Grahamstown , Bourdieu, Pierre, 1930-2002 , Sen, Amartya, 1933-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3370 , http://hdl.handle.net/10962/d1012655
- Description: Foundation provisioning has a long history in South Africa, and is central to the transformation agenda, particularly the broadening of successful participation in higher education (HE). As access initiatives underpinned by various conceptualisations, foundation programmes evolved from peripheral, to semi-integrated and finally fully integrated curricular models in the form of current Extended Studies Programmes (ESPs). Underpinning the provision of Extended Studies is the acknowledgment that students who enter institutions are essentially ill equipped to cope with the demands of higher education studies, “leaving institutions themselves free of the responsibility of student failure” (Akoojee & Nkomo, 2007:391). This under-preparedness has been attributed to the ‘articulation gap’ between secondary and higher education, which in turn contributes to low retention and graduation rates (CHE, 2013:17). Situated within an overarching commitment to access and success, the Extended Studies Programme attempts to systematically address the ‘articulation gap’. This study evaluated the extent to which the Rhodes University Humanities Extended Studies Programme is achieving its objectives from a transformation perspective, specifically the broadening of successful participation in higher education. The majority of previous works on the evaluation of foundation programmes focused on measurable dimensions of student access and success – that is retention and graduation rates. This thesis considered both the measurable outcomes of the programme as well as the actual teaching and learning process. Given the shifts that have taken place in foundation provisioning, the evaluation of the current model of foundation provisioning necessitated their location in history. Therefore, the evaluation of the Rhodes University Humanities Extended Studies Programme was undertaken in view of the shifts, achievements, challenges and critics of its predecessor programmes. Specifically, the following dimensions were considered in the evaluation of the programme: i) assumptions underpinning the design and purpose of the programme, ii) teaching and learning practices in the programme, iii) student and staff perceptions of the programme, iv) students’ experiences of the programme, v) the validity of the programme in the broader institution, and vi) the measurable outcomes of the programme − that is retention and graduation rates of students enrolled in the programme. The triangulation of qualitative data collection techniques provided access into the different layers of institutional relations, processes and structures, which not only affect teaching and learning in the programme, but also determine students’ engagement with different academic and social aspects of the broader university. The theoretical insights of Pierre Bourdieu and Amartya Sen were integrated in order to provide analytical tools for both understanding the causes of inequalities in higher education, and evaluating institutional processes and structures that perpetuate or transform inequalities. Whilst Bourdieu’s social reproduction thesis exposed the ways in which social structures shape educational processes and outcomes, Sen’s capability approach provided tools for evaluating both institutional arrangements and individual capabilities – that is, the freedom to achieve desired educational outcomes (Sen, 1992:48).
- Full Text:
Adherence to antiretroviral therapy in children in Zimbabwe: a randomized control trial to validate a new self-reported adherence monitoring tool
- Authors: Mugore, Linnetie
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54734 , vital:26607
- Description: Background: Among children taking antiretroviral therapy (ART), self-reports have been widely reported to over-estimate adherence levels. Pill count adherence levels are often lower than self-reported levels, with unannounced home pill count adherence being lower than facility based pill count adherence. There is often poor agreement between pill count adherence levels and those measured using other objective adherence measuring methods such as Medication Event Monitoring Systems (MEMS®), which is widely viewed as the gold standard for adherence measurement. Objectives: The aim of this study was to design and evaluate a new self-reported paediatric adherence monitoring tool, assess the feasibility of using pill count methods in monitoring adherence and identify challenges to reporting adherence among children on ART in rural and urban Zimbabwe. Methods A dual centre, superiority, parallel design RCT was conducted to evaluate the newly-developed visually- and verbally-cued „past 10 days‟ tool for the assessment of adherence in children on ART at two sites in Zimbabwe; Harare Central Children‟s Hospital in an urban setting, and Murambinda Mission Hospital, a rural site. Child-caregiver pairs presenting to one of these facilities for the child‟s review of ART and refill of the medication were recruited, signed informed consent obtained, and were randomised for self-reported adherence monitoring into either the experimental group („new 10-day tool‟) or the control group („PACTG-style‟ self-report tool). Data (demographic, socioeconomic, and reported adherence) were collected in individual interviews with child-caregiver pairs. Additional adherence monitoring methods used for both groups included the Morisky-8-Item Medication Adherence Scale (MMAS-8) and a facility based pill count. FGDs were held with groups of caregivers and groups of children ≥13 years of age to understand reasons for non-adherence as well as issues around reporting non-adherence. Superiority testing was conducted by comparing adherent proportions and their confidence intervals (95% CI). Further concurrent validity test was done using the Mann-Whitney U test to evaluate the relationship between the new tool and the MMAS-8 scores. Agreement between the child and caregiver reports of adherence was used as a test of reliability of the new tool using the kappa statistic. Socio-demographic, clinical and care-related factors associated with adherence were identified using reported adherence in both child and caregiver groups in a logistic regression model. Two pill count methods were assessed for feasibility using the proportions of children with complete data for calculating adherence levels, and their CI and a comparison of the two methods, a routinely-used method and one that incorporated the reported residual quantity (RRQ) of medication at last refill. Results : Analysis included 245 child-caregiver pairs, 123 in the experimental group and 122 in the control group. The median age for children was 9 years. In the experimental group, adherence by caregiver and child reports ranged from 94.3% - 98.4% and 78.4% - 96.1%, and those in the control group ranged from 89.2% - 97.5% and 71.2% - 98.1%, respectively. There was no significant difference between adherence levels in the two groups. Adherence levels measured by both the experimental and control tools were found to be associated with MMAS-8 adherence levels (p <0.05). Agreement between child- and caregiver-reported adherence was moderate though significant (kappa; 0.407, p <0.05). Only about half of the children had adequate data to compute pill counts. Proportions adherent at 95% cut-off were 39% by the „routine pill count‟ and 58% by the „Pill count RRQ‟. Being an orphan was associated with child reported-adherence whereas use of non-human reminders, having a maternal relative as a primary caregiver and knowledge of dose frequency, were all associated with caregiver-reported adherence. Major causes of non-adherence mentioned during the FGDs included interference of medication administration times with scheduling of routine socio-economic activities and lack of support from some non-biological caregivers. Reporting of non-adherence appeared to be hampered by perceptions of negative reactions by healthcare workers to these reports and by caregivers being unaware that the child missed some doses. Conclusions: The „new 10-day tool‟ was not shown to be superior to the „PACTG-style tool‟ in detecting non-adherence, however this new tool was found to be a valid and reliable adherence monitoring tool that included a moderately long recall period of 10 days, can be applied without the need for the respondent to remember names of individual medicines in the
- Full Text:
- Authors: Mugore, Linnetie
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54734 , vital:26607
- Description: Background: Among children taking antiretroviral therapy (ART), self-reports have been widely reported to over-estimate adherence levels. Pill count adherence levels are often lower than self-reported levels, with unannounced home pill count adherence being lower than facility based pill count adherence. There is often poor agreement between pill count adherence levels and those measured using other objective adherence measuring methods such as Medication Event Monitoring Systems (MEMS®), which is widely viewed as the gold standard for adherence measurement. Objectives: The aim of this study was to design and evaluate a new self-reported paediatric adherence monitoring tool, assess the feasibility of using pill count methods in monitoring adherence and identify challenges to reporting adherence among children on ART in rural and urban Zimbabwe. Methods A dual centre, superiority, parallel design RCT was conducted to evaluate the newly-developed visually- and verbally-cued „past 10 days‟ tool for the assessment of adherence in children on ART at two sites in Zimbabwe; Harare Central Children‟s Hospital in an urban setting, and Murambinda Mission Hospital, a rural site. Child-caregiver pairs presenting to one of these facilities for the child‟s review of ART and refill of the medication were recruited, signed informed consent obtained, and were randomised for self-reported adherence monitoring into either the experimental group („new 10-day tool‟) or the control group („PACTG-style‟ self-report tool). Data (demographic, socioeconomic, and reported adherence) were collected in individual interviews with child-caregiver pairs. Additional adherence monitoring methods used for both groups included the Morisky-8-Item Medication Adherence Scale (MMAS-8) and a facility based pill count. FGDs were held with groups of caregivers and groups of children ≥13 years of age to understand reasons for non-adherence as well as issues around reporting non-adherence. Superiority testing was conducted by comparing adherent proportions and their confidence intervals (95% CI). Further concurrent validity test was done using the Mann-Whitney U test to evaluate the relationship between the new tool and the MMAS-8 scores. Agreement between the child and caregiver reports of adherence was used as a test of reliability of the new tool using the kappa statistic. Socio-demographic, clinical and care-related factors associated with adherence were identified using reported adherence in both child and caregiver groups in a logistic regression model. Two pill count methods were assessed for feasibility using the proportions of children with complete data for calculating adherence levels, and their CI and a comparison of the two methods, a routinely-used method and one that incorporated the reported residual quantity (RRQ) of medication at last refill. Results : Analysis included 245 child-caregiver pairs, 123 in the experimental group and 122 in the control group. The median age for children was 9 years. In the experimental group, adherence by caregiver and child reports ranged from 94.3% - 98.4% and 78.4% - 96.1%, and those in the control group ranged from 89.2% - 97.5% and 71.2% - 98.1%, respectively. There was no significant difference between adherence levels in the two groups. Adherence levels measured by both the experimental and control tools were found to be associated with MMAS-8 adherence levels (p <0.05). Agreement between child- and caregiver-reported adherence was moderate though significant (kappa; 0.407, p <0.05). Only about half of the children had adequate data to compute pill counts. Proportions adherent at 95% cut-off were 39% by the „routine pill count‟ and 58% by the „Pill count RRQ‟. Being an orphan was associated with child reported-adherence whereas use of non-human reminders, having a maternal relative as a primary caregiver and knowledge of dose frequency, were all associated with caregiver-reported adherence. Major causes of non-adherence mentioned during the FGDs included interference of medication administration times with scheduling of routine socio-economic activities and lack of support from some non-biological caregivers. Reporting of non-adherence appeared to be hampered by perceptions of negative reactions by healthcare workers to these reports and by caregivers being unaware that the child missed some doses. Conclusions: The „new 10-day tool‟ was not shown to be superior to the „PACTG-style tool‟ in detecting non-adherence, however this new tool was found to be a valid and reliable adherence monitoring tool that included a moderately long recall period of 10 days, can be applied without the need for the respondent to remember names of individual medicines in the
- Full Text:
An evaluation of macroinvertebrate-based biomonitoring and ecotoxicological assessments of deteriorating environmental water quality in the Swartkops River, South Africa
- Authors: Odume, Oghenekaro Nelson
- Date: 2014
- Subjects: Water -- Pollution -- South Africa -- Swartkops River , Water quality biological assessment -- South Africa -- Swartkops River , Environmental toxicology -- South Africa -- Swartkops River , Environmental monitoring -- South Africa -- Swartkops River , Aquatic invertebrates -- Effect of water pollution on -- South Africa -- Swartkops River , Chironomidae -- Effect of water pollution on -- South Africa -- Swartkops River , Freshwater ecology -- South Africa -- Swartkops River
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6046 , http://hdl.handle.net/10962/d1013156
- Description: Freshwater resources are increasingly subject to pollution because of escalating human population growth, accompanied by urbanisation, industrialisation, and the increased demand for food. Consequently, freshwater quality, and aquatic ecosystem structure and function have been severely impaired. The Swartkops River, which drains an urbanised and industrialised catchment in the Eastern Cape of South Africa, is no exception. An integrated environmental water quality (EWQ) approach is needed to measure the impacts of deteriorating water quality on its aquatic ecosystem structure and function to sustain these vital ecosystem-attributes. In this study, an integrated EWQ approach, which included i) analysis of water physico-chemical variables; ii) macroinvertebrate-based family-level taxonomic- and traits-based community analysis; iii) Chironomidae species-level taxonomic- and traits-based community analysis; iv) Chironomidae deformity-based sub-lethal analysis; and v) experimental investigation of long-term wastewater effluent effects, using model stream ecosystems, were applied to investigate environmental water quality in the Swartkops River. One upstream reference site and three downstream sites in the Swartkops River were monitored over a period of three years (August 2009 – September 2012). The family-level taxonomic community responses based on the South African Scoring System version 5 (SASS5) and a newly developed Swartkops multimetric index indicated very poor river health conditions for the three downstream sites, compared with the good condition of the upstream site. The Chironomidae species-level responses in the three downstream sites provided evidence of differences in biotic impairments, which were not evident with the family-level taxonomic data at these sites, thus highlighting the importance of species identification in freshwater biomonitoring. The family-level traits-based approach (TBA) showed that macroinvertebrates with gills and lungs were more abundant at the upstream site, decreasing markedly at the downstream sites. The relative abundance of macroinvertebrates relying on aerial and tegument respiration increased at the downstream sites compared with the upstream sites. The results of the family-level TBA highlighted the inextricable link between the traits-based approach (TBA) and taxonomic identification, clearly showing that the TBA is additional to, and not an alternative to, taxonomic recognition because important traits, e.g. reproductive cannot be used at a coarse taxonomic identification. A novel chironomid species traits-based functional strategies approach developed in this study, based on species combining similar sets of traits, proved sensitive in diagnosing the main abiotic water physico-chemical stressors. The functional traits responded predictably to deteriorating water quality and provided an adaptive and mechanistic basis for interpreting chironomid species occurrences at the four sampling sites, providing insight into why certain chironomid species occurred at one site but not at the other. Chironomid deformities provided evidence of sub-lethal in-stream biological response to deteriorating water quality. A newly developed deformity-based extended toxic score index proved sensitive, enabling the discrimination of the sampling sites, indicating that a biomonitoring tool based on sub-lethal effects could be used to assess the effects of deteriorating water quality before it reached lethal levels. Empirical evidence based on the taxonomic, traits and sub-lethal responses suggested that the changes in macroinvertebrate community structure were caused chiefly by the discharge of wastewater effluents into the river. This was supported by the model-stream ecosystem results indicating significant effects of effluents on the macroinvertebrate community structure, similar to the observed in-stream responses. The model stream results indicated that improved physico-chemical effluent quality compliance after 50% effluent dilution did not significantly reduce the effects of the effluent on the macroinvertebrate communities, showing that ecologically-based methods rather than physico-chemical measures alone are necessary to assess effluent quality. Finally, the results of the multi-criteria approach were integrated to propose tools to manage environmental water quality in the Swartkops River, and the benefits of the study were highlighted in the context of biomonitoring in South Africa.
- Full Text:
- Authors: Odume, Oghenekaro Nelson
- Date: 2014
- Subjects: Water -- Pollution -- South Africa -- Swartkops River , Water quality biological assessment -- South Africa -- Swartkops River , Environmental toxicology -- South Africa -- Swartkops River , Environmental monitoring -- South Africa -- Swartkops River , Aquatic invertebrates -- Effect of water pollution on -- South Africa -- Swartkops River , Chironomidae -- Effect of water pollution on -- South Africa -- Swartkops River , Freshwater ecology -- South Africa -- Swartkops River
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6046 , http://hdl.handle.net/10962/d1013156
- Description: Freshwater resources are increasingly subject to pollution because of escalating human population growth, accompanied by urbanisation, industrialisation, and the increased demand for food. Consequently, freshwater quality, and aquatic ecosystem structure and function have been severely impaired. The Swartkops River, which drains an urbanised and industrialised catchment in the Eastern Cape of South Africa, is no exception. An integrated environmental water quality (EWQ) approach is needed to measure the impacts of deteriorating water quality on its aquatic ecosystem structure and function to sustain these vital ecosystem-attributes. In this study, an integrated EWQ approach, which included i) analysis of water physico-chemical variables; ii) macroinvertebrate-based family-level taxonomic- and traits-based community analysis; iii) Chironomidae species-level taxonomic- and traits-based community analysis; iv) Chironomidae deformity-based sub-lethal analysis; and v) experimental investigation of long-term wastewater effluent effects, using model stream ecosystems, were applied to investigate environmental water quality in the Swartkops River. One upstream reference site and three downstream sites in the Swartkops River were monitored over a period of three years (August 2009 – September 2012). The family-level taxonomic community responses based on the South African Scoring System version 5 (SASS5) and a newly developed Swartkops multimetric index indicated very poor river health conditions for the three downstream sites, compared with the good condition of the upstream site. The Chironomidae species-level responses in the three downstream sites provided evidence of differences in biotic impairments, which were not evident with the family-level taxonomic data at these sites, thus highlighting the importance of species identification in freshwater biomonitoring. The family-level traits-based approach (TBA) showed that macroinvertebrates with gills and lungs were more abundant at the upstream site, decreasing markedly at the downstream sites. The relative abundance of macroinvertebrates relying on aerial and tegument respiration increased at the downstream sites compared with the upstream sites. The results of the family-level TBA highlighted the inextricable link between the traits-based approach (TBA) and taxonomic identification, clearly showing that the TBA is additional to, and not an alternative to, taxonomic recognition because important traits, e.g. reproductive cannot be used at a coarse taxonomic identification. A novel chironomid species traits-based functional strategies approach developed in this study, based on species combining similar sets of traits, proved sensitive in diagnosing the main abiotic water physico-chemical stressors. The functional traits responded predictably to deteriorating water quality and provided an adaptive and mechanistic basis for interpreting chironomid species occurrences at the four sampling sites, providing insight into why certain chironomid species occurred at one site but not at the other. Chironomid deformities provided evidence of sub-lethal in-stream biological response to deteriorating water quality. A newly developed deformity-based extended toxic score index proved sensitive, enabling the discrimination of the sampling sites, indicating that a biomonitoring tool based on sub-lethal effects could be used to assess the effects of deteriorating water quality before it reached lethal levels. Empirical evidence based on the taxonomic, traits and sub-lethal responses suggested that the changes in macroinvertebrate community structure were caused chiefly by the discharge of wastewater effluents into the river. This was supported by the model-stream ecosystem results indicating significant effects of effluents on the macroinvertebrate community structure, similar to the observed in-stream responses. The model stream results indicated that improved physico-chemical effluent quality compliance after 50% effluent dilution did not significantly reduce the effects of the effluent on the macroinvertebrate communities, showing that ecologically-based methods rather than physico-chemical measures alone are necessary to assess effluent quality. Finally, the results of the multi-criteria approach were integrated to propose tools to manage environmental water quality in the Swartkops River, and the benefits of the study were highlighted in the context of biomonitoring in South Africa.
- Full Text:
An exploration of an environmental resource management course for sustainable development practitioners in Kenya : a case study
- Authors: Oteki, Jane Bosibori
- Date: 2014
- Subjects: Environmental management -- Kenya Sustainable development -- Kenya Environmental management -- Study and teaching -- Kenya Sustainable development -- Study and teaching -- Kenya Environmental education -- Study and teaching -- Kenya Environmental sciences -- Study and teaching -- Kenya Technical University of Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1964 , http://hdl.handle.net/10962/d1011611
- Description: Environmental challenges facing the world currently call for efforts that can avert eminent disasters related to these challenges. In an effort to engage in conservation, the Environmental Resource Management course at Technical University offers an opportunity to train for sustainable development in the country. However, the development and implementation of courses aimed at developing careers in sustainability in institutions of higher learning are coming under scrutiny as questions are being asked about their contributions to sustainable development. This research explored the Environmental Resource Management course to understand how it was developed and implemented to address a practitioner in the environmental resources conservation sector. The study surfaced the contradictions in the course which can be used as a lens to re-orient the course to enable a practitioner in education for sustainable development to emerge. In Kenya, vocational courses in environmental education are a career choice for secondary school leavers and those engaged in the environmental conservation sector. This study carried out at Technical University of Kenya (TU-K) between January 2009 and April 2012 aimed at exploring how a diploma course: Environmental Resource Management (ERM) enabled the learners to become practitioners in environmental resource management. It surfaced contradictions and suggested transformative approaches to re-orient the course for sustainable development. This was necessitated by the paradigm shift in environmental education from environmental conservation education that emphasised ecological studies to Education for Sustainable Development that is broader and more holistic, encompassing social, economic and environmental aspects. The course has to be re-orientated to enable a practitioner in Education for Sustainable Development (ESD) to emerge considering the United Nations Decade of Education for Sustainable Development (UNDESD, 2005-2014). The course aims at training personnel for deployment in environmental conservation and management organisations to work as resource officers/supervisors in national parks, forestry management, water management, energy development projects officers, etc. Data was gathered through document analysis, questionnaires, interviews, observation and focus group discussions. Cultural Historical Activity Theory (CHAT) was engaged in surfacing contradictions in the Environmental Resource Management learning system in terms of its development and implementation. While Communities of Practice (COP) principles were used as the ontological underpinning for the ERM course. The results indicate that the ERM course was revised between 1998 and 2002 by experts from Saskatchewan Institute of Science and Technology (SIAST) in collaboration with TU-K staff under the programme, enhancing environmental management in Kenya. The research also established that the ERM course review process was informed by sustainable development principles, as outlined in Agenda 21. Further it was realised that the Develop a Curriculum (DACUM) process was engaged to develop the learning units. This course development envisaged Competency Based Education (CBE) as the main mode of the ERM delivery. CBE is student centred and allows for multi-entry and exit. The study however realised that at implementation this approach was partially incorporated, as the country’s education system is examination oriented and time bound. The study findings indicate that most of the units taught were on ecosystem management with the social and economic aspects having less space and time, therefore the three pillars of Education for Sustainable Development were not adequately addressed in the course to enable a practitioner in the concept to emerge. Also teaching and learning in the course was found to be more theoretical than practical with little hands-on activities because the main focus of the course was to enable the learners to acquire a certificate through examination rather than gain the appropriate competencies. Although the course was found to be enhancing ESD in relation to global and local sustainability issues, there were contradictions or challenges in the system that affected full realisation of the skills, knowledge, values and attitudes. For example the exclusion of the recipient staff in the planning of the course, lack of training of the lecturers on how to train on CBE, insufficient practical field excursions devoid of community engagement, lack of funds, lack of equipment and poor coordination. This study recommends a re-orientation of the course to a more practical approach to teaching such as: • Engagement of students with the community to solve real-life environmental problems; • Mainstreaming ESD in all courses in the institutions of higher learning so that environmental concerns are addressed by everyone; • Reviewing the educational policy to encourage solving of real-life environmental problems rather than passing theoretical examinations; • Enhancing competency based learning to enable students to become competent in their areas of specialisation; • Encouraging networking and direct involvement of the students in the community instead of spending more time in class; and • Establishing a Community of Practice among the students in Higher Education Institutions to enhance conservation practices. The study contributes in-depth insight into exploring courses in Technical Vocational Education and Training institutions using Communities of Practice as a lens within the Kenyan context. It gives some empirical and explanatory insight into how learning can emerge and be expanded in Education for Sustainable Development through relevant courses such as tje Environmental Resource Management course. It also provides learning tools to work with contradictions that arise from socio-cultural and historical dimensions of learning about natural resources in the Kenyan context. Its other key contribution is that it provides further insight into the re-orientation of the ERM courses to embrace ESD for a broader and a more holistic approach to natural resources conservation and poverty alleviation processes that are critical for responding to socio-ecological issues and risks and development challenges in Kenya.
- Full Text:
- Authors: Oteki, Jane Bosibori
- Date: 2014
- Subjects: Environmental management -- Kenya Sustainable development -- Kenya Environmental management -- Study and teaching -- Kenya Sustainable development -- Study and teaching -- Kenya Environmental education -- Study and teaching -- Kenya Environmental sciences -- Study and teaching -- Kenya Technical University of Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1964 , http://hdl.handle.net/10962/d1011611
- Description: Environmental challenges facing the world currently call for efforts that can avert eminent disasters related to these challenges. In an effort to engage in conservation, the Environmental Resource Management course at Technical University offers an opportunity to train for sustainable development in the country. However, the development and implementation of courses aimed at developing careers in sustainability in institutions of higher learning are coming under scrutiny as questions are being asked about their contributions to sustainable development. This research explored the Environmental Resource Management course to understand how it was developed and implemented to address a practitioner in the environmental resources conservation sector. The study surfaced the contradictions in the course which can be used as a lens to re-orient the course to enable a practitioner in education for sustainable development to emerge. In Kenya, vocational courses in environmental education are a career choice for secondary school leavers and those engaged in the environmental conservation sector. This study carried out at Technical University of Kenya (TU-K) between January 2009 and April 2012 aimed at exploring how a diploma course: Environmental Resource Management (ERM) enabled the learners to become practitioners in environmental resource management. It surfaced contradictions and suggested transformative approaches to re-orient the course for sustainable development. This was necessitated by the paradigm shift in environmental education from environmental conservation education that emphasised ecological studies to Education for Sustainable Development that is broader and more holistic, encompassing social, economic and environmental aspects. The course has to be re-orientated to enable a practitioner in Education for Sustainable Development (ESD) to emerge considering the United Nations Decade of Education for Sustainable Development (UNDESD, 2005-2014). The course aims at training personnel for deployment in environmental conservation and management organisations to work as resource officers/supervisors in national parks, forestry management, water management, energy development projects officers, etc. Data was gathered through document analysis, questionnaires, interviews, observation and focus group discussions. Cultural Historical Activity Theory (CHAT) was engaged in surfacing contradictions in the Environmental Resource Management learning system in terms of its development and implementation. While Communities of Practice (COP) principles were used as the ontological underpinning for the ERM course. The results indicate that the ERM course was revised between 1998 and 2002 by experts from Saskatchewan Institute of Science and Technology (SIAST) in collaboration with TU-K staff under the programme, enhancing environmental management in Kenya. The research also established that the ERM course review process was informed by sustainable development principles, as outlined in Agenda 21. Further it was realised that the Develop a Curriculum (DACUM) process was engaged to develop the learning units. This course development envisaged Competency Based Education (CBE) as the main mode of the ERM delivery. CBE is student centred and allows for multi-entry and exit. The study however realised that at implementation this approach was partially incorporated, as the country’s education system is examination oriented and time bound. The study findings indicate that most of the units taught were on ecosystem management with the social and economic aspects having less space and time, therefore the three pillars of Education for Sustainable Development were not adequately addressed in the course to enable a practitioner in the concept to emerge. Also teaching and learning in the course was found to be more theoretical than practical with little hands-on activities because the main focus of the course was to enable the learners to acquire a certificate through examination rather than gain the appropriate competencies. Although the course was found to be enhancing ESD in relation to global and local sustainability issues, there were contradictions or challenges in the system that affected full realisation of the skills, knowledge, values and attitudes. For example the exclusion of the recipient staff in the planning of the course, lack of training of the lecturers on how to train on CBE, insufficient practical field excursions devoid of community engagement, lack of funds, lack of equipment and poor coordination. This study recommends a re-orientation of the course to a more practical approach to teaching such as: • Engagement of students with the community to solve real-life environmental problems; • Mainstreaming ESD in all courses in the institutions of higher learning so that environmental concerns are addressed by everyone; • Reviewing the educational policy to encourage solving of real-life environmental problems rather than passing theoretical examinations; • Enhancing competency based learning to enable students to become competent in their areas of specialisation; • Encouraging networking and direct involvement of the students in the community instead of spending more time in class; and • Establishing a Community of Practice among the students in Higher Education Institutions to enhance conservation practices. The study contributes in-depth insight into exploring courses in Technical Vocational Education and Training institutions using Communities of Practice as a lens within the Kenyan context. It gives some empirical and explanatory insight into how learning can emerge and be expanded in Education for Sustainable Development through relevant courses such as tje Environmental Resource Management course. It also provides learning tools to work with contradictions that arise from socio-cultural and historical dimensions of learning about natural resources in the Kenyan context. Its other key contribution is that it provides further insight into the re-orientation of the ERM courses to embrace ESD for a broader and a more holistic approach to natural resources conservation and poverty alleviation processes that are critical for responding to socio-ecological issues and risks and development challenges in Kenya.
- Full Text:
An investigation into the bacterial diversity associated with South African latrunculid sponges that produce bioactive secondary metabolites
- Authors: Walmsley, Tara Aisling
- Date: 2014
- Subjects: Sponges -- South Africa -- Algoa Bay , Sponges -- Classification , Metabolites -- South Africa -- Algoa Bay , Marine metabolites -- South Africa -- Algoa Bay , PQQ (Biochemistry) , Bacterial diversity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4109 , http://hdl.handle.net/10962/d1012943
- Description: Algoa Bay Latrunculid sponges are well known for their production of cytotoxic pyrroloiminoquinones with speculation that these secondary metabolites may have a microbial origin. This study describes a thorough investigation into the bacterial community associated with Tsitsikamma favus, Tsitsikamma scurra a newly described Latrunculia sp. and a yellow encrusting sponge associated with T. scurra. Molecular and chemical characterisation were used in conjunction with traditional taxonomy in identification of the sponge specimens. The 28S rRNA and COX1 analysis confirmed the traditional taxonomy with T. favus and T. scurra being very closely related. Chemical analysis revealed that T. favus and T. scurra shared the discorhabdins 2,4-debromo-3-dihydrodiscorhabdin C, 7,8-dehydro-3-dihydrodiscorhabdin C and 14-bromo-1-hydroxy-discorhabdin V in common with each other and Tsitsikamma pedunculata indicating that these pyrroloiminoquinones are common to Tsitsikamma sponges in general. The bacterial community associated with T. favus was explored using 16S rRNA molecular techniques including DGGE, clonal libraries of full length 16S rRNA genes, as well as 454 pyrosequencing. DGGE analysis revealed that the bacterial community associated with T. favus appeared to be highly conserved, which was confirmed by both the clone library and 454 pyrosequencing, with the Betaproteobacteria as the most dominant class. Further exploration into T. favus, as well as T. scurra, Latrunculia sp. and the yellow encrusting sponge indicated that the bacterial populations associated with each of these sponge species were conserved and species specific. OTU analysis to the species level revealed that T. favus and T. scurra shared an abundant Spirochaete species in common while the most abundant species in the Latrunculia sp. and the yellow encrusting sponge belonged to the class Betaproteobacteria. The exclusivity of the tsitsikammamines to T. favus precipitated attempts to culture the T. favus associated bacteria, with a focus on the dominant betaproteobacterium as indicated by the 16S rRNA clone library. Actinobacteria associated with the Algoa Bay sponge specimens were also cultured and the actinobacterial isolates were sent for screening against Mycobacterium aurum with two Kocuria kristinae isolates and a Streptomyces albdioflavus isolate showing good antimycobacterial activity.
- Full Text:
- Authors: Walmsley, Tara Aisling
- Date: 2014
- Subjects: Sponges -- South Africa -- Algoa Bay , Sponges -- Classification , Metabolites -- South Africa -- Algoa Bay , Marine metabolites -- South Africa -- Algoa Bay , PQQ (Biochemistry) , Bacterial diversity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4109 , http://hdl.handle.net/10962/d1012943
- Description: Algoa Bay Latrunculid sponges are well known for their production of cytotoxic pyrroloiminoquinones with speculation that these secondary metabolites may have a microbial origin. This study describes a thorough investigation into the bacterial community associated with Tsitsikamma favus, Tsitsikamma scurra a newly described Latrunculia sp. and a yellow encrusting sponge associated with T. scurra. Molecular and chemical characterisation were used in conjunction with traditional taxonomy in identification of the sponge specimens. The 28S rRNA and COX1 analysis confirmed the traditional taxonomy with T. favus and T. scurra being very closely related. Chemical analysis revealed that T. favus and T. scurra shared the discorhabdins 2,4-debromo-3-dihydrodiscorhabdin C, 7,8-dehydro-3-dihydrodiscorhabdin C and 14-bromo-1-hydroxy-discorhabdin V in common with each other and Tsitsikamma pedunculata indicating that these pyrroloiminoquinones are common to Tsitsikamma sponges in general. The bacterial community associated with T. favus was explored using 16S rRNA molecular techniques including DGGE, clonal libraries of full length 16S rRNA genes, as well as 454 pyrosequencing. DGGE analysis revealed that the bacterial community associated with T. favus appeared to be highly conserved, which was confirmed by both the clone library and 454 pyrosequencing, with the Betaproteobacteria as the most dominant class. Further exploration into T. favus, as well as T. scurra, Latrunculia sp. and the yellow encrusting sponge indicated that the bacterial populations associated with each of these sponge species were conserved and species specific. OTU analysis to the species level revealed that T. favus and T. scurra shared an abundant Spirochaete species in common while the most abundant species in the Latrunculia sp. and the yellow encrusting sponge belonged to the class Betaproteobacteria. The exclusivity of the tsitsikammamines to T. favus precipitated attempts to culture the T. favus associated bacteria, with a focus on the dominant betaproteobacterium as indicated by the 16S rRNA clone library. Actinobacteria associated with the Algoa Bay sponge specimens were also cultured and the actinobacterial isolates were sent for screening against Mycobacterium aurum with two Kocuria kristinae isolates and a Streptomyces albdioflavus isolate showing good antimycobacterial activity.
- Full Text:
An investigation into the development of knowledge and strategies for the teaching of visual literacy in under-resourced Eastern Cape schools
- Authors: Mbelani, Madeyandile
- Date: 2014
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64401 , vital:28540
- Description: This thesis reports on a multiple case study PhD project that aimed to investigate meaningful and critical development of knowledge and strategies to teach visual literacy, a component of English First Additional Language (FAL) in six under-resourced schools of the Eastern Cape of South Africa. The study begins by locating visual literacy within a broad framework of literacy as a social practice, and discusses its importance. Further, it discusses complexities of making sense of and teaching visual literacy, especially for the majority of in-service teachers who experienced visual literacy neither as learners nor as teacher trainees. The gap between the curriculum and teachers’ classroom practices is what triggered this study to adopt a transformative paradigm. The main research question is, “How can teacher professional development in English Language Teaching advance in-service teachers’ knowledge of and strategies for meaningful and critical teaching and learning of visual literacy?” To respond to this question, I drew on cultural historical activity theory (CHAT) and critical realism (CR) to design four phases of this study that incorporated the seven stages of an expansive learning cycle. These phases focussed on exploring and expanding teachers’ sense making and teaching of visual literacy. I collected data through interviews, document analysis, videoed lessons and change laboratory (CL) workshops. I designed a data analysis tool that brought together CHAT, CR, multimodal social semiotics, critical discourse analysis and pedagogical discourse to make sense of the data. Through a process of reflexivity, the study illuminated layers of factors that constrained meaningful and critical teaching of visual literacy in the empirical, the actual and the real domains of reality. These factors include teachers’ unconscious reproduction of discourses of domination, their intolerance of diverse cultural discourses, resistance to curriculum change, and the fact that they are comfortable with the status quo. I brought these factors to CL workshops for expansive learning. The study contributes in-depth insight into English FAL in-service teacher development in the area of visual literacy. By locating the study within meaning making and teaching of visual literacy, it was possible to interrogate access, diversity, domination and design in teachers’ classroom practices. As a result of this study participants were made aware of the extent to which these factors enabled or hindered meaningful and critical teaching. Participants repositioned themselves as subjects of the activity system, thereby mobilising their agency to take control of the structures and cultures that condition their teaching.
- Full Text:
- Authors: Mbelani, Madeyandile
- Date: 2014
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64401 , vital:28540
- Description: This thesis reports on a multiple case study PhD project that aimed to investigate meaningful and critical development of knowledge and strategies to teach visual literacy, a component of English First Additional Language (FAL) in six under-resourced schools of the Eastern Cape of South Africa. The study begins by locating visual literacy within a broad framework of literacy as a social practice, and discusses its importance. Further, it discusses complexities of making sense of and teaching visual literacy, especially for the majority of in-service teachers who experienced visual literacy neither as learners nor as teacher trainees. The gap between the curriculum and teachers’ classroom practices is what triggered this study to adopt a transformative paradigm. The main research question is, “How can teacher professional development in English Language Teaching advance in-service teachers’ knowledge of and strategies for meaningful and critical teaching and learning of visual literacy?” To respond to this question, I drew on cultural historical activity theory (CHAT) and critical realism (CR) to design four phases of this study that incorporated the seven stages of an expansive learning cycle. These phases focussed on exploring and expanding teachers’ sense making and teaching of visual literacy. I collected data through interviews, document analysis, videoed lessons and change laboratory (CL) workshops. I designed a data analysis tool that brought together CHAT, CR, multimodal social semiotics, critical discourse analysis and pedagogical discourse to make sense of the data. Through a process of reflexivity, the study illuminated layers of factors that constrained meaningful and critical teaching of visual literacy in the empirical, the actual and the real domains of reality. These factors include teachers’ unconscious reproduction of discourses of domination, their intolerance of diverse cultural discourses, resistance to curriculum change, and the fact that they are comfortable with the status quo. I brought these factors to CL workshops for expansive learning. The study contributes in-depth insight into English FAL in-service teacher development in the area of visual literacy. By locating the study within meaning making and teaching of visual literacy, it was possible to interrogate access, diversity, domination and design in teachers’ classroom practices. As a result of this study participants were made aware of the extent to which these factors enabled or hindered meaningful and critical teaching. Participants repositioned themselves as subjects of the activity system, thereby mobilising their agency to take control of the structures and cultures that condition their teaching.
- Full Text:
An investigation into XSets of primitive behaviours for emergent behaviour in stigmergic and message passing antlike agents
- Authors: Chibaya, Colin
- Date: 2014
- Subjects: Ants -- Behavior -- Computer programs , Insects -- Behavior -- Computer programs , Ant communities -- Behavior , Insect societies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4698 , http://hdl.handle.net/10962/d1012965
- Description: Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
- Full Text:
- Authors: Chibaya, Colin
- Date: 2014
- Subjects: Ants -- Behavior -- Computer programs , Insects -- Behavior -- Computer programs , Ant communities -- Behavior , Insect societies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4698 , http://hdl.handle.net/10962/d1012965
- Description: Ants are fascinating creatures - not so much because they are intelligent on their own, but because as a group they display compelling emergent behaviour (the extent to which one observes features in a swarm which cannot be traced back to the actions of swarm members). What does each swarm member do which allows deliberate engineering of emergent behaviour? We investigate the development of a language for programming swarms of ant agents towards desired emergent behaviour. Five aspects of stigmergic (pheromone sensitive computational devices in which a non-symbolic form of communication that is indirectly mediated via the environment arises) and message passing ant agents (computational devices which rely on implicit communication spaces in which direction vectors are shared one-on-one) are studied. First, we investigate the primitive behaviours which characterize ant agents' discrete actions at individual levels. Ten such primitive behaviours are identified as candidate building blocks of the ant agent language sought. We then study mechanisms in which primitive behaviours are put together into XSets (collection of primitive behaviours, parameter values, and meta information which spells out how and when primitive behaviours are used). Various permutations of XSets are possible which define the search space for best performer XSets for particular tasks. Genetic programming principles are proposed as a search strategy for best performer XSets that would allow particular emergent behaviour to occur. XSets in the search space are evolved over various genetic generations and tested for abilities to allow path finding (as proof of concept). XSets are ranked according to the indices of merit (fitness measures which indicate how well XSets allow particular emergent behaviour to occur) they achieve. Best performer XSets for the path finding task are identifed and reported. We validate the results yield when best performer XSets are used with regard to normality, correlation, similarities in variation, and similarities between mean performances over time. Commonly, the simulation results yield pass most statistical tests. The last aspect we study is the application of best performer XSets to different problem tasks. Five experiments are administered in this regard. The first experiment assesses XSets' abilities to allow multiple targets location (ant agents' abilities to locate continuous regions of targets), and found out that best performer XSets are problem independent. However both categories of XSets are sensitive to changes in agent density. We test the influences of individual primitive behaviours and the effects of the sequences of primitive behaviours to the indices of merit of XSets and found out that most primitive behaviours are indispensable, especially when specific sequences are prescribed. The effects of pheromone dissipation to the indices of merit of stigmergic XSets are also scrutinized. Precisely, dissipation is not causal. Rather, it enhances convergence. Overall, this work successfully identify the discrete primitive behaviours of stigmergic and message passing ant-like devices. It successfully put these primitive behaviours together into XSets which characterize a language for programming ant-like devices towards desired emergent behaviour. This XSets approach is a new ant language representation with which a wider domain of emergent tasks can be resolved.
- Full Text:
An investigation of parameter relationships in a high-speed digital multimedia environment
- Authors: Chigwamba, Nyasha
- Date: 2014
- Subjects: Multimedia communications , Digital communications , Local area networks (Computer networks) , Computer network architectures , Computer network protocols , Computer sound processing , Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4725 , http://hdl.handle.net/10962/d1021153
- Description: With the rapid adoption of multimedia network technologies, a number of companies and standards bodies are introducing technologies that enhance user experience in networked multimedia environments. These technologies focus on device discovery, connection management, control, and monitoring. This study focused on control and monitoring. Multimedia networks make it possible for devices that are part of the same network to reside in different physical locations. These devices contain parameters that are used to control particular features, such as speaker volume, bass, amplifier gain, and video resolution. It is often necessary for changes in one parameter to affect other parameters, such as a synchronised change between volume and bass parameters, or collective control of multiple parameters. Thus, relationships are required between the parameters. In addition, some devices contain parameters, such as voltage, temperature, and audio level, that require constant monitoring to enable corrective action when thresholds are exceeded. Therefore, a mechanism for monitoring networked devices is required. This thesis proposes relationships that are essential for the proper functioning of a multimedia network and that should, therefore, be incorporated in standard form into a protocol, such that all devices can depend on them. Implementation mechanisms for these relationships were created. Parameter grouping and monitoring capabilities within mixing console implementations and existing control protocols were reviewed. A number of requirements for parameter grouping and monitoring were derived from this review. These requirements include a formal classification of relationship types, the ability to create relationships between parameters with different underlying value units, the ability to create relationships between parameters residing on different devices on a network, and the use of an event-driven mechanism for parameter monitoring. These requirements were the criteria used to govern the implementation mechanisms that were created as part of this study. Parameter grouping and monitoring mechanisms were implemented for the XFN protocol. The mechanisms implemented fulfil the requirements derived from the review of capabilities of mixing consoles and existing control protocols. The formal classification of relationship types was implemented within XFN parameters using lists that keep track of the relationships between each XFN parameter and other XFN parameters that reside on the same device or on other devices on the network. A common value unit, known as the global unit, was defined for use as the value format within value update messages between XFN parameters that have relationships. Mapping tables were used to translate the global unit values to application-specific (universal) units, such as decibels (dB). A mechanism for bulk parameter retrieval within the XFN protocol was augmented to produce an event-driven mechanism for parameter monitoring. These implementation mechanisms were applied to an XFN-protocol-compliant graphical control application to demonstrate their usage within an end user context. At the time of this study, the XFN protocol was undergoing standardisation within the Audio Engineering Society. The AES-64 standard has now been approved. Most of the implementation mechanisms resulting from this study have been incorporated into this standard.
- Full Text:
- Authors: Chigwamba, Nyasha
- Date: 2014
- Subjects: Multimedia communications , Digital communications , Local area networks (Computer networks) , Computer network architectures , Computer network protocols , Computer sound processing , Sound -- Recording and reproducing -- Digital techniques
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4725 , http://hdl.handle.net/10962/d1021153
- Description: With the rapid adoption of multimedia network technologies, a number of companies and standards bodies are introducing technologies that enhance user experience in networked multimedia environments. These technologies focus on device discovery, connection management, control, and monitoring. This study focused on control and monitoring. Multimedia networks make it possible for devices that are part of the same network to reside in different physical locations. These devices contain parameters that are used to control particular features, such as speaker volume, bass, amplifier gain, and video resolution. It is often necessary for changes in one parameter to affect other parameters, such as a synchronised change between volume and bass parameters, or collective control of multiple parameters. Thus, relationships are required between the parameters. In addition, some devices contain parameters, such as voltage, temperature, and audio level, that require constant monitoring to enable corrective action when thresholds are exceeded. Therefore, a mechanism for monitoring networked devices is required. This thesis proposes relationships that are essential for the proper functioning of a multimedia network and that should, therefore, be incorporated in standard form into a protocol, such that all devices can depend on them. Implementation mechanisms for these relationships were created. Parameter grouping and monitoring capabilities within mixing console implementations and existing control protocols were reviewed. A number of requirements for parameter grouping and monitoring were derived from this review. These requirements include a formal classification of relationship types, the ability to create relationships between parameters with different underlying value units, the ability to create relationships between parameters residing on different devices on a network, and the use of an event-driven mechanism for parameter monitoring. These requirements were the criteria used to govern the implementation mechanisms that were created as part of this study. Parameter grouping and monitoring mechanisms were implemented for the XFN protocol. The mechanisms implemented fulfil the requirements derived from the review of capabilities of mixing consoles and existing control protocols. The formal classification of relationship types was implemented within XFN parameters using lists that keep track of the relationships between each XFN parameter and other XFN parameters that reside on the same device or on other devices on the network. A common value unit, known as the global unit, was defined for use as the value format within value update messages between XFN parameters that have relationships. Mapping tables were used to translate the global unit values to application-specific (universal) units, such as decibels (dB). A mechanism for bulk parameter retrieval within the XFN protocol was augmented to produce an event-driven mechanism for parameter monitoring. These implementation mechanisms were applied to an XFN-protocol-compliant graphical control application to demonstrate their usage within an end user context. At the time of this study, the XFN protocol was undergoing standardisation within the Audio Engineering Society. The AES-64 standard has now been approved. Most of the implementation mechanisms resulting from this study have been incorporated into this standard.
- Full Text:
An investigation of protocol command translation as a means to enable interoperability between networked audio devices
- Authors: Igumbor, Osedum Peter
- Date: 2014
- Subjects: Streaming audio Data transmission systems Computer network protocols Computer networks -- Management Command languages (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4689 , http://hdl.handle.net/10962/d1011128
- Description: Digital audio networks allow multiple channels of audio to be streamed between devices. This eliminates the need for many different cables to route audio between devices. An added advantage of digital audio networks is the ability to configure and control the networked devices from a common control point. Common control of networked devices enables a sound engineer to establish and destroy audio stream connections between networked devices that are distances apart. On a digital audio network, an audio transport technology enables the exchange of data streams. Typically, an audio transport technology is capable of transporting both control messages and audio data streams. There exist a number of audio transport technologies. Some of these technologies implement data transport by exchanging OSI/ISO layer 2 data frames, while others transport data within OSI/ISO layer 3 packets. There are some approaches to achieving interoperability between devices that utilize different audio transport technologies. A digital audio device typically implements an audio control protocol, which enables it process configuration and control messages from a remote controller. An audio control protocol also defines the structure of the messages that are exchanged between compliant devices. There are currently a wide range of audio control protocols. Some audio control protocols utilize layer 3 audio transport technology, while others utilize layer 2 audio transport technology. An audio device can only communicate with other devices that implement the same control protocol, irrespective of a common transport technology that connects the devices. The existence of different audio control protocols among devices on a network results in a situation where the devices are unable to communicate with each other. Furthermore, a single control application is unable to establish or destroy audio stream connections between the networked devices, since they implement different control protocols. When an audio engineer is designing an audio network installation, this interoperability challenge restricts the choice of devices that can be included. Even when audio transport interoperability has been achieved, common control of the devices remains a challenge. This research investigates protocol command translation as a means to enable interoperability between networked audio devices that implement different audio control protocols. It proposes the use of a command translator that is capable of receiving messages conforming to one protocol from any of the networked devices, translating the received message to conform to a different control protocol, then transmitting the translated message to the intended target which understands the translated protocol message. In so doing, the command translator enables common control of the networked devices, since a control application is able to configure and control devices that conform to different protocols by utilizing the command translator to perform appropriate protocol translation.
- Full Text:
- Authors: Igumbor, Osedum Peter
- Date: 2014
- Subjects: Streaming audio Data transmission systems Computer network protocols Computer networks -- Management Command languages (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4689 , http://hdl.handle.net/10962/d1011128
- Description: Digital audio networks allow multiple channels of audio to be streamed between devices. This eliminates the need for many different cables to route audio between devices. An added advantage of digital audio networks is the ability to configure and control the networked devices from a common control point. Common control of networked devices enables a sound engineer to establish and destroy audio stream connections between networked devices that are distances apart. On a digital audio network, an audio transport technology enables the exchange of data streams. Typically, an audio transport technology is capable of transporting both control messages and audio data streams. There exist a number of audio transport technologies. Some of these technologies implement data transport by exchanging OSI/ISO layer 2 data frames, while others transport data within OSI/ISO layer 3 packets. There are some approaches to achieving interoperability between devices that utilize different audio transport technologies. A digital audio device typically implements an audio control protocol, which enables it process configuration and control messages from a remote controller. An audio control protocol also defines the structure of the messages that are exchanged between compliant devices. There are currently a wide range of audio control protocols. Some audio control protocols utilize layer 3 audio transport technology, while others utilize layer 2 audio transport technology. An audio device can only communicate with other devices that implement the same control protocol, irrespective of a common transport technology that connects the devices. The existence of different audio control protocols among devices on a network results in a situation where the devices are unable to communicate with each other. Furthermore, a single control application is unable to establish or destroy audio stream connections between the networked devices, since they implement different control protocols. When an audio engineer is designing an audio network installation, this interoperability challenge restricts the choice of devices that can be included. Even when audio transport interoperability has been achieved, common control of the devices remains a challenge. This research investigates protocol command translation as a means to enable interoperability between networked audio devices that implement different audio control protocols. It proposes the use of a command translator that is capable of receiving messages conforming to one protocol from any of the networked devices, translating the received message to conform to a different control protocol, then transmitting the translated message to the intended target which understands the translated protocol message. In so doing, the command translator enables common control of the networked devices, since a control application is able to configure and control devices that conform to different protocols by utilizing the command translator to perform appropriate protocol translation.
- Full Text:
Aspects of the ecology of leopards (Panthera Pardus) in the Little Karoo, South Africa
- Authors: Mann, Gareth
- Date: 2014
- Subjects: Leopard -- South Africa -- Little Karoo Leopard -- Monitoring -- South Africa -- Little Karoo Leopard -- Ecology -- South Africa -- Little Karoo Wildlife monitoring -- South Africa Wildlife conservation -- South Africa Animal populations -- South Africa -- Little Karoo Leopard -- Conservation -- South Africa -- Little Karoo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5855 , http://hdl.handle.net/10962/d1012241
- Description: Leopards (Panthera pardus) are the most common large predators, free roaming outside of protected areas across most of South Africa. Leopard persistence is attributed to their tolerance of rugged terrain that is subject to less development pressure, as well as their cryptic behaviour. Nevertheless, existing leopard populations are threatened indirectly by ongoing transformation of natural habitat and directly through hunting and conflict with livestock farmers. Together these threats may further isolate leopards to fragmented areas of core natural habitat. I studied leopard habitat preferences, population density, diet and the attitudes of landowners towards leopards in the Little Karoo, Western Cape, South Africa, an area of mixed land-use that contains elements of three overlapping global biodiversity hotspots. Data were gathered between 2010 and 2012 using camera traps set up at 141 sites over an area of ~3100km², GPS tracking collars fitted to three male leopards, scat samples (n=76), interviews with landowners (n=53) analysed in combination with geographical information system (GIS) layers. My results reveal that leopards preferred rugged, mountainous terrain of intermediate elevation, avoiding low-lying, open areas where human disturbance was generally greater. Despite relatively un-fragmented habitat within my study area, the leopard population density (0.75 leopards/100km²) was one of the lowest yet recorded in South Africa. This may reflect low prey densities in mountain refuges in addition to historical human persecution in the area. Currently local landowners are more tolerant of leopards than other wildlife species with incidents of conflict involving leopards being rare relative to black-backed jackals (Canis mesomelas), baboons (Papio hamadryas), caracals (Caracal caracal) and porcupine (Hystrix africaeaustralis). Although current levels of conflict between leopards and stock farmers are low, leopards do depredate livestock, which constitute 10-15% of their diet. Improved livestock husbandry measures and co-operation between conservation authorities and farmers are necessary to mitigate such conflict and balance economic security with biodiversity conservation in the region. Leopards are the only remaining top predators throughout much of the Little Karoo and the Western Cape and as such are predicted to play a critical role in ecosystem structure and the survival of other species. Current high levels of connectivity between areas of suitable leopard habitat bode well for the conservation status of leopards within this region and future conservation efforts need to ensure that narrow corridors linking such habitat are preserved. The potential for leopards to serve as both an umbrella and a flagship species for biodiversity conservation suggests that long term monitoring of this population would be a conservation priority for the Little Karoo.
- Full Text:
- Authors: Mann, Gareth
- Date: 2014
- Subjects: Leopard -- South Africa -- Little Karoo Leopard -- Monitoring -- South Africa -- Little Karoo Leopard -- Ecology -- South Africa -- Little Karoo Wildlife monitoring -- South Africa Wildlife conservation -- South Africa Animal populations -- South Africa -- Little Karoo Leopard -- Conservation -- South Africa -- Little Karoo
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5855 , http://hdl.handle.net/10962/d1012241
- Description: Leopards (Panthera pardus) are the most common large predators, free roaming outside of protected areas across most of South Africa. Leopard persistence is attributed to their tolerance of rugged terrain that is subject to less development pressure, as well as their cryptic behaviour. Nevertheless, existing leopard populations are threatened indirectly by ongoing transformation of natural habitat and directly through hunting and conflict with livestock farmers. Together these threats may further isolate leopards to fragmented areas of core natural habitat. I studied leopard habitat preferences, population density, diet and the attitudes of landowners towards leopards in the Little Karoo, Western Cape, South Africa, an area of mixed land-use that contains elements of three overlapping global biodiversity hotspots. Data were gathered between 2010 and 2012 using camera traps set up at 141 sites over an area of ~3100km², GPS tracking collars fitted to three male leopards, scat samples (n=76), interviews with landowners (n=53) analysed in combination with geographical information system (GIS) layers. My results reveal that leopards preferred rugged, mountainous terrain of intermediate elevation, avoiding low-lying, open areas where human disturbance was generally greater. Despite relatively un-fragmented habitat within my study area, the leopard population density (0.75 leopards/100km²) was one of the lowest yet recorded in South Africa. This may reflect low prey densities in mountain refuges in addition to historical human persecution in the area. Currently local landowners are more tolerant of leopards than other wildlife species with incidents of conflict involving leopards being rare relative to black-backed jackals (Canis mesomelas), baboons (Papio hamadryas), caracals (Caracal caracal) and porcupine (Hystrix africaeaustralis). Although current levels of conflict between leopards and stock farmers are low, leopards do depredate livestock, which constitute 10-15% of their diet. Improved livestock husbandry measures and co-operation between conservation authorities and farmers are necessary to mitigate such conflict and balance economic security with biodiversity conservation in the region. Leopards are the only remaining top predators throughout much of the Little Karoo and the Western Cape and as such are predicted to play a critical role in ecosystem structure and the survival of other species. Current high levels of connectivity between areas of suitable leopard habitat bode well for the conservation status of leopards within this region and future conservation efforts need to ensure that narrow corridors linking such habitat are preserved. The potential for leopards to serve as both an umbrella and a flagship species for biodiversity conservation suggests that long term monitoring of this population would be a conservation priority for the Little Karoo.
- Full Text:
Becoming and being: a critical realist study into the emergence of identity in emergency medical science students, and the construct of graduate attributes
- Authors: Millar, Bernadette Theresa
- Date: 2014
- Subjects: Critical realism , Emergency medical personnel -- Psychology , Emergency medical services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1327 , http://hdl.handle.net/10962/d1013175
- Description: This critical realist thesis seeks to understand how student, graduate and professional identities emerge in Emergency Medical Science (EMS) students at a South African University of Technology (UoT) as well as in professional paramedics in the Emergency Medical Care Services (EMCS). It further considers the construct of graduate attributes (GAs) and its relationship to emergence of identity and influence on curriculum design. The research design is that of a case study. The theoretical framework is critical realism whose depth ontology posits three domains of reality. Causal powers and generative mechanisms exist in the Real domain which cause events or phenomena to emerge in the Actual domain that are experienced in the Empirical domain. Using retroduction one may come to explore some of the causes for the event. Using Bhaskar’s concepts of identity, the self, absence and emergence, ontology and four-planar social being, a Bhaskarian explanatory framework of identity to explore the emergence of identity has been created. In exploring graduate attributes, a critical realist question is posed: “What must the world be like for GAs to exist” to explore the possibilities of the existence of GAs. It was found that student identity emerges diachronically in three moments, while professional paramedic identity starts to emerge during the third year of study mainly through the structure, culture and agency of workplace-based learning. In answer to the critical realist question it was found that GAs emerge from the neoliberalist commodification of universities. In seeking an alternative to GAs, traits and attitudes were explored. It was found that these emerge from curriculum, interplay of departmental structure, culture and agency of and from students’ being which makes them ontologically radically different from GAs. This study concludes that student, graduate and professional identities emerge from a person’s core constellational identity diachronically within four-planar social being and the interplay of structure, culture and agency. GAs cannot be related to the emergence of identity and curriculum design because of their ontology; however, if traits and attitudes are substituted for GAs, a close relationship does exist between emergence of identity, traits and attitudes and curriculum design.
- Full Text:
- Authors: Millar, Bernadette Theresa
- Date: 2014
- Subjects: Critical realism , Emergency medical personnel -- Psychology , Emergency medical services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1327 , http://hdl.handle.net/10962/d1013175
- Description: This critical realist thesis seeks to understand how student, graduate and professional identities emerge in Emergency Medical Science (EMS) students at a South African University of Technology (UoT) as well as in professional paramedics in the Emergency Medical Care Services (EMCS). It further considers the construct of graduate attributes (GAs) and its relationship to emergence of identity and influence on curriculum design. The research design is that of a case study. The theoretical framework is critical realism whose depth ontology posits three domains of reality. Causal powers and generative mechanisms exist in the Real domain which cause events or phenomena to emerge in the Actual domain that are experienced in the Empirical domain. Using retroduction one may come to explore some of the causes for the event. Using Bhaskar’s concepts of identity, the self, absence and emergence, ontology and four-planar social being, a Bhaskarian explanatory framework of identity to explore the emergence of identity has been created. In exploring graduate attributes, a critical realist question is posed: “What must the world be like for GAs to exist” to explore the possibilities of the existence of GAs. It was found that student identity emerges diachronically in three moments, while professional paramedic identity starts to emerge during the third year of study mainly through the structure, culture and agency of workplace-based learning. In answer to the critical realist question it was found that GAs emerge from the neoliberalist commodification of universities. In seeking an alternative to GAs, traits and attitudes were explored. It was found that these emerge from curriculum, interplay of departmental structure, culture and agency of and from students’ being which makes them ontologically radically different from GAs. This study concludes that student, graduate and professional identities emerge from a person’s core constellational identity diachronically within four-planar social being and the interplay of structure, culture and agency. GAs cannot be related to the emergence of identity and curriculum design because of their ontology; however, if traits and attitudes are substituted for GAs, a close relationship does exist between emergence of identity, traits and attitudes and curriculum design.
- Full Text:
Biochemical mechanisms towards understanding Alzheimer's disease
- Authors: Padayachee, Eden Rebecca
- Date: 2014
- Subjects: Alzheimer's disease Nitric-oxide synthase Biochemical markers Amyloid beta-protein Peptide hormones
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4103 , http://hdl.handle.net/10962/d1011092
- Description: The start of the amyloidogenic pathway in Alzheimer’s disease (AD) begins with the deposition of the Aβ₁₋₄₂ peptide surrounded by astrocytes. High levels of arginine and low amounts of neuronal nitric oxide synthase (nNOS) are associated with AD. These astrocytes store reserve arginine that is eventually metabolized by nNOS, within the vicinity of the Aβ₁₋₄₂ peptide. We propose the existence of an association vs. dissociation equilibrium between Aβ and nNOS such that nNOS is an amyloidogenic catalyst for fibrils. When Aβ binds to nNOS, it inhibits the activity of the enzyme (association phase). However when the amyloid peptide dissociates into a form that can no longer bind, later deduced as a fibril, the activity is restored. Thus, the interaction of Aβ with nNOS could serve to regulate the interaction between nNOS and arginine by restoring activity of the enzyme but at the same time promoting fibrillogenesis. Given this event occurring with the neuron, both nNOS and amyloid can serve as a biomarker for the early onset of AD. The enzyme nNOS catalyzed the formation of fibrils in the presence of Aβ peptides, while Ag nps were shown to reverse the fibril formation from Aβ peptides more so than Au and curcumin either through electrostatic or π-π stacking (aromatic) influences. Our studies have shown that the fragments of Aβ₁₋₄₂ i.e. the pentapeptide (Aβ₁₇₋₂₁) and the three glycine zipper peptides (Aβ₂₅₋₂₉, Aβ₂₉₋₃₃, Aβ₃₃₋₃₇) and the full length glycine zipper stretch (Aβ₂₅₋₃₇) all inhibited nNOS activity to varying degrees. The peptides Aβ₁₇₋₂₁ and Aβ₂₉₋₃₃ with their respective Ki values of 5.1 μM and 7.5 μM inhibited the enzyme the most. The Ki values for reversed sequenced peptides (Aβ₁₇₋₂₁r and Aβ₂₉₋₃₃r) were two fold greater than that of the original peptides while the Ki values for the polar forms (Aβ₁₇₋₂₁p and Aβ₂₉₋₃₃p) were between 3-4 fold greater than that of the original peptides. It was also found that Ag nps (Ki = 0.12 μM) inhibited the activity of nNOS the most compared to Au nps; (Ki = 0.15 μM) and curcumin (Ki = 0.25 μM). At 298K, all the ligands bound at a single site on the enzyme (n=1) and a single Trp residue (θ =1), (later identified as Trp678) was made available on the enzyme surface for quenching by the ligands. Increasing the temperature from 298K-313K, increased the value of Ksv and pointed to a dynamic quenching mechanism for Aβ peptides, nps and curcumin interaction with nNOS. The positive signs for entropy and enthalpy for all Aβ peptides nps and curcumin pointed to hydrophobic–hydrophobic interaction with the enzyme. The fact that Kd increased with temperature emphasized the endothermic nature of the binding reaction and the requirement of thermal energy to aid in diffusion of the ligand to the active site. It was concluded that the binding reaction between the ligands and nNOS was non-spontaneous and endothermic at low temperatures (+ΔG) but spontaneous at high temperatures (-ΔG). The two amino acids Tyr706 and Trp678 moved from their original positions, subject to ligand binding. Trp678 moved a minimum distance of 5 Å toward the heme while Tyr706 moved a maximum distance of 14 Å away from the heme. AutoDock 4.2 was a valuable tool in monitoring the distance of Trp678 within the enzyme interior and fluorescence resonance energy transfer (FRET) was efficient in monitoring the distance moved by Trp residues on the enzyme surface.
- Full Text:
- Authors: Padayachee, Eden Rebecca
- Date: 2014
- Subjects: Alzheimer's disease Nitric-oxide synthase Biochemical markers Amyloid beta-protein Peptide hormones
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4103 , http://hdl.handle.net/10962/d1011092
- Description: The start of the amyloidogenic pathway in Alzheimer’s disease (AD) begins with the deposition of the Aβ₁₋₄₂ peptide surrounded by astrocytes. High levels of arginine and low amounts of neuronal nitric oxide synthase (nNOS) are associated with AD. These astrocytes store reserve arginine that is eventually metabolized by nNOS, within the vicinity of the Aβ₁₋₄₂ peptide. We propose the existence of an association vs. dissociation equilibrium between Aβ and nNOS such that nNOS is an amyloidogenic catalyst for fibrils. When Aβ binds to nNOS, it inhibits the activity of the enzyme (association phase). However when the amyloid peptide dissociates into a form that can no longer bind, later deduced as a fibril, the activity is restored. Thus, the interaction of Aβ with nNOS could serve to regulate the interaction between nNOS and arginine by restoring activity of the enzyme but at the same time promoting fibrillogenesis. Given this event occurring with the neuron, both nNOS and amyloid can serve as a biomarker for the early onset of AD. The enzyme nNOS catalyzed the formation of fibrils in the presence of Aβ peptides, while Ag nps were shown to reverse the fibril formation from Aβ peptides more so than Au and curcumin either through electrostatic or π-π stacking (aromatic) influences. Our studies have shown that the fragments of Aβ₁₋₄₂ i.e. the pentapeptide (Aβ₁₇₋₂₁) and the three glycine zipper peptides (Aβ₂₅₋₂₉, Aβ₂₉₋₃₃, Aβ₃₃₋₃₇) and the full length glycine zipper stretch (Aβ₂₅₋₃₇) all inhibited nNOS activity to varying degrees. The peptides Aβ₁₇₋₂₁ and Aβ₂₉₋₃₃ with their respective Ki values of 5.1 μM and 7.5 μM inhibited the enzyme the most. The Ki values for reversed sequenced peptides (Aβ₁₇₋₂₁r and Aβ₂₉₋₃₃r) were two fold greater than that of the original peptides while the Ki values for the polar forms (Aβ₁₇₋₂₁p and Aβ₂₉₋₃₃p) were between 3-4 fold greater than that of the original peptides. It was also found that Ag nps (Ki = 0.12 μM) inhibited the activity of nNOS the most compared to Au nps; (Ki = 0.15 μM) and curcumin (Ki = 0.25 μM). At 298K, all the ligands bound at a single site on the enzyme (n=1) and a single Trp residue (θ =1), (later identified as Trp678) was made available on the enzyme surface for quenching by the ligands. Increasing the temperature from 298K-313K, increased the value of Ksv and pointed to a dynamic quenching mechanism for Aβ peptides, nps and curcumin interaction with nNOS. The positive signs for entropy and enthalpy for all Aβ peptides nps and curcumin pointed to hydrophobic–hydrophobic interaction with the enzyme. The fact that Kd increased with temperature emphasized the endothermic nature of the binding reaction and the requirement of thermal energy to aid in diffusion of the ligand to the active site. It was concluded that the binding reaction between the ligands and nNOS was non-spontaneous and endothermic at low temperatures (+ΔG) but spontaneous at high temperatures (-ΔG). The two amino acids Tyr706 and Trp678 moved from their original positions, subject to ligand binding. Trp678 moved a minimum distance of 5 Å toward the heme while Tyr706 moved a maximum distance of 14 Å away from the heme. AutoDock 4.2 was a valuable tool in monitoring the distance of Trp678 within the enzyme interior and fluorescence resonance energy transfer (FRET) was efficient in monitoring the distance moved by Trp residues on the enzyme surface.
- Full Text:
Can expansive (social) learning processes strengthen organisational learning for improved wetland management in a plantation forestry company, and if so how? : a case study of Mondi
- Authors: Lindley, David Stewart
- Date: 2014
- Subjects: Mondi Group , Wetland management -- South Africa , Wetland conservation -- Study and teaching (Continuing education) , Employees -- Training of -- South Africa , Action theory , Critical realism , Social learning , Environmental education -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2003 , http://hdl.handle.net/10962/d1015661
- Description: Mondi is an international packaging and paper company that manages over 300 000 ha of land in South Africa. After over a decade of working with Mondi to improve its wetland management, wetland sustainability practices were still not integrated into the broader forestry operations, despite some significant cases of successful wetland rehabilitation. An interventionist research project was therefore conducted to explore the factors inhibiting improved wetland management, and determine if and how expansive social learning processes could strengthen organisational learning and development to overcome these factors. In doing so, the research has investigated how informal adult learning supports organisational change to strengthen wetland and environmental sustainability practices, within a corporate plantation forestry context. How individual and/or group-based learning interactions translate to the collective, at the level of organisational change was a key issue probed in this study. The following three research questions were used to guide the research: 1. What tensions and contradictions exist in wetland management in a plantation forestry company? 2. Can expansive learning begin to address the tensions and contradictions that exist in wetland management in a plantation forestry company, for improved sustainability practices? 3. Can expansive social learning strengthen organisational learning and development, enabling Mondi to improve its wetland sustainability practices, and if so how does it do this? Cultural historical activity theory (CHAT) and the theory of expansive learning provided an epistemological framework for the research. The philosophy of critical realism gave ontological depth to the research, and contributed to a deeper understanding of CHAT and expansive learning. Critical realism was therefore used as a philosophy to underlabour the theoretical framework of the research. However CHAT and expansive learning could not provide the depth of detail required to explain how the expansive learning, organisational social change, and boundary crossings that are necessary for assembling the collective were taking place. Realist social theory (developed out of critical realism by Margaret Archer as an ontologically located theory of how and why social change occurs, or does not) supported the research to do this. The morphogenetic framework was used as a methodology for applying realist social theory. The expansive learning cycle was used as a methodology for applying CHAT and the theory of expansive learning; guiding the development of new knowledge creation required by Mondi staff to identify contradictions and associated tensions inhibiting wetland management, understand their root causes, and develop solutions. Through the expansive learning process, the tensions and contradictions become generative as a tool supporting expansive social learning, rather than as a means to an end where universal consensus was reached on how to circumvent the contradictions. The research was conducted in five phases: • Phase 1: Contextual profiling to identify and describe three activity systems in Mondi responsible for wetland management: 1) siviculture foresters; 2) environmental specialists; 3) community engagement facilitators. The data was generated and analysed through through document analysis, 17 interviews, 2nd generation CHAT analysis, and Critical Realist generative mechanism analysis; • Phase 2: Analysis and identification of tensions and contradictions through a first interventionist workshop. Modelling new solutions to deal with contractions, and examining and testing new models in and after the second interventionist workshop; • Phase 3: Implementing new models as wetland management projects and involved project implementation. This included boundary crossing practices of staff in the three activity systems, reflection and re-view in a further five progress review/interventionist workshops, and a management meeting and seminar; • Phase 4: Reflecting on the expansive learning process, results, and consolidation of changed practices, through nine reflective interviews and field observations; • Phase 5: Morphogenic/stasis analysis of the organisational change and development catalysed via the expansive social learning process (or not). The research found that expansive social learning processes supported organisational learning and development for improved wetland management by: 1) strengthening the scope, depth, and sophistication of participant understanding; 2) expanding the ways staff interact and collaboratively work together; 3) democratising decision making; 4) improving social relations between staff, reducing power differentials, and creating stronger relationships; 5) enhancing participant reflexivity through deeper understanding of social structures and cultural systems, and changing them to support improved wetland and environmental practice of staff, and developing the organisational structures and processes to strengthen organisational learning and development; and 6) using the contradictions identified as generative mechanisms to stimulate and catalyse organisational learning and development for changed wetland/environmental management.
- Full Text:
- Authors: Lindley, David Stewart
- Date: 2014
- Subjects: Mondi Group , Wetland management -- South Africa , Wetland conservation -- Study and teaching (Continuing education) , Employees -- Training of -- South Africa , Action theory , Critical realism , Social learning , Environmental education -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2003 , http://hdl.handle.net/10962/d1015661
- Description: Mondi is an international packaging and paper company that manages over 300 000 ha of land in South Africa. After over a decade of working with Mondi to improve its wetland management, wetland sustainability practices were still not integrated into the broader forestry operations, despite some significant cases of successful wetland rehabilitation. An interventionist research project was therefore conducted to explore the factors inhibiting improved wetland management, and determine if and how expansive social learning processes could strengthen organisational learning and development to overcome these factors. In doing so, the research has investigated how informal adult learning supports organisational change to strengthen wetland and environmental sustainability practices, within a corporate plantation forestry context. How individual and/or group-based learning interactions translate to the collective, at the level of organisational change was a key issue probed in this study. The following three research questions were used to guide the research: 1. What tensions and contradictions exist in wetland management in a plantation forestry company? 2. Can expansive learning begin to address the tensions and contradictions that exist in wetland management in a plantation forestry company, for improved sustainability practices? 3. Can expansive social learning strengthen organisational learning and development, enabling Mondi to improve its wetland sustainability practices, and if so how does it do this? Cultural historical activity theory (CHAT) and the theory of expansive learning provided an epistemological framework for the research. The philosophy of critical realism gave ontological depth to the research, and contributed to a deeper understanding of CHAT and expansive learning. Critical realism was therefore used as a philosophy to underlabour the theoretical framework of the research. However CHAT and expansive learning could not provide the depth of detail required to explain how the expansive learning, organisational social change, and boundary crossings that are necessary for assembling the collective were taking place. Realist social theory (developed out of critical realism by Margaret Archer as an ontologically located theory of how and why social change occurs, or does not) supported the research to do this. The morphogenetic framework was used as a methodology for applying realist social theory. The expansive learning cycle was used as a methodology for applying CHAT and the theory of expansive learning; guiding the development of new knowledge creation required by Mondi staff to identify contradictions and associated tensions inhibiting wetland management, understand their root causes, and develop solutions. Through the expansive learning process, the tensions and contradictions become generative as a tool supporting expansive social learning, rather than as a means to an end where universal consensus was reached on how to circumvent the contradictions. The research was conducted in five phases: • Phase 1: Contextual profiling to identify and describe three activity systems in Mondi responsible for wetland management: 1) siviculture foresters; 2) environmental specialists; 3) community engagement facilitators. The data was generated and analysed through through document analysis, 17 interviews, 2nd generation CHAT analysis, and Critical Realist generative mechanism analysis; • Phase 2: Analysis and identification of tensions and contradictions through a first interventionist workshop. Modelling new solutions to deal with contractions, and examining and testing new models in and after the second interventionist workshop; • Phase 3: Implementing new models as wetland management projects and involved project implementation. This included boundary crossing practices of staff in the three activity systems, reflection and re-view in a further five progress review/interventionist workshops, and a management meeting and seminar; • Phase 4: Reflecting on the expansive learning process, results, and consolidation of changed practices, through nine reflective interviews and field observations; • Phase 5: Morphogenic/stasis analysis of the organisational change and development catalysed via the expansive social learning process (or not). The research found that expansive social learning processes supported organisational learning and development for improved wetland management by: 1) strengthening the scope, depth, and sophistication of participant understanding; 2) expanding the ways staff interact and collaboratively work together; 3) democratising decision making; 4) improving social relations between staff, reducing power differentials, and creating stronger relationships; 5) enhancing participant reflexivity through deeper understanding of social structures and cultural systems, and changing them to support improved wetland and environmental practice of staff, and developing the organisational structures and processes to strengthen organisational learning and development; and 6) using the contradictions identified as generative mechanisms to stimulate and catalyse organisational learning and development for changed wetland/environmental management.
- Full Text:
Challenging desire : performing whiteness in post-apartheid South Africa
- Authors: Smit, Sonja
- Date: 2014
- Subjects: Performance art -- South Africa , Bailey, Brett, 1967- , Cohen, Steven, 1962- , Antwoord (Musical group) , MacGarry, Michael , Eurocentrism -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2164 , http://hdl.handle.net/10962/d1016358
- Description: The central argument of this thesis asserts that in the process of challenging dominant subject positions, such as whiteness, performance creates the possibilities for new or alternative arrangements of desire. It examines how the creative process of desire is forestalled (reified) by habitual representations of whiteness as a privileged position, and proposes that performance can be a valid form of resistance to static conceptions of race and subjectivity. The discussion takes into account how the privilege of whiteness finds representation through forms of neo-liberalism and neo-colonialism in the post apartheid context. The analysis focuses on the work of white South African artists whose work offers a critique from within the privileged “centre” of whiteness. The research is situated within the inter-disciplinary field of performance studies entailing a reading and application of critical texts to the analysis. Alongside this qualitative methodology surfaces a subjective dialogue with the information presented on whiteness. Part Two includes an analysis of Steven Cohen’s The Cradle of Humankind (2011), Brett Bailey’s Exhibit A (2011) and Michael MacGarry’s LHR-JNB (2010). Each section examines the way in which the respective works engage in a questioning of whiteness through performance. Part Three investigates South African rap-rave duo, Die Antwoord and how their appropriation of Zef interrogates desires for an essential authenticity. Part Four focuses on my own performance practice and the proposed value of engaging with a form of practice-led research. This is particularly relevant in relation to critical race studies that require a level of self-reflexivity from the researcher. It presents an analysis of the work entitled Villain (2012) as a disturbance of theatrical desire through a process of ‘becoming’. This notion of meaning and identity as ‘becoming’ is argued as a strategy to challenge prevailing modes of perception which can possibly restore the production of desire to the viewer. The thesis concludes with the notion that performance can offer a mode of immanent ethics which is significant in creating both vulnerable and critical forms of whiteness.
- Full Text:
- Authors: Smit, Sonja
- Date: 2014
- Subjects: Performance art -- South Africa , Bailey, Brett, 1967- , Cohen, Steven, 1962- , Antwoord (Musical group) , MacGarry, Michael , Eurocentrism -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2164 , http://hdl.handle.net/10962/d1016358
- Description: The central argument of this thesis asserts that in the process of challenging dominant subject positions, such as whiteness, performance creates the possibilities for new or alternative arrangements of desire. It examines how the creative process of desire is forestalled (reified) by habitual representations of whiteness as a privileged position, and proposes that performance can be a valid form of resistance to static conceptions of race and subjectivity. The discussion takes into account how the privilege of whiteness finds representation through forms of neo-liberalism and neo-colonialism in the post apartheid context. The analysis focuses on the work of white South African artists whose work offers a critique from within the privileged “centre” of whiteness. The research is situated within the inter-disciplinary field of performance studies entailing a reading and application of critical texts to the analysis. Alongside this qualitative methodology surfaces a subjective dialogue with the information presented on whiteness. Part Two includes an analysis of Steven Cohen’s The Cradle of Humankind (2011), Brett Bailey’s Exhibit A (2011) and Michael MacGarry’s LHR-JNB (2010). Each section examines the way in which the respective works engage in a questioning of whiteness through performance. Part Three investigates South African rap-rave duo, Die Antwoord and how their appropriation of Zef interrogates desires for an essential authenticity. Part Four focuses on my own performance practice and the proposed value of engaging with a form of practice-led research. This is particularly relevant in relation to critical race studies that require a level of self-reflexivity from the researcher. It presents an analysis of the work entitled Villain (2012) as a disturbance of theatrical desire through a process of ‘becoming’. This notion of meaning and identity as ‘becoming’ is argued as a strategy to challenge prevailing modes of perception which can possibly restore the production of desire to the viewer. The thesis concludes with the notion that performance can offer a mode of immanent ethics which is significant in creating both vulnerable and critical forms of whiteness.
- Full Text:
Challenging hegemony? : a provincial perspective on the limits of policy challenge in the South African state
- Authors: Reynolds, John
- Date: 2014 , 2014-06-24
- Subjects: Community development -- South Africa -- Eastern Cape , South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3372 , http://hdl.handle.net/10962/d1013031
- Description: This thesis provides a provincial perspective on the limits of policy challenge within the post-apartheid South African state. This perspective is located in the Eastern Cape Province of South Africa, which is one of the poorest of the nine provinces into which the national territory was divided during the constitutional negotiations prior to the landmark democratic elections of 1994. The empirical foundation for this perspective is an analysis of the process of developing the Eastern Cape Provincial Growth and Development Plan 2004-2014 (PGDP), which took place in 2002-2004. Starting with a broader theoretical discussion, followed by a brief contextual analysis of the South African economy, the structure of the post-apartheid South African state, and key growth and development policies, the more detailed engagement with the PGDP process is undertaken. Drawing on Jessop’s (2008) strategic-relational approach, this thesis argues that the PGDP process arose within a particular spatio-temporal context where new opportunities for policy challenge were possible, but that such challenge had to be negotiated on a strategically selective terrain on which that challenge was neutralised. The PGDP process unfolded as a complex dialectic of agency and a range of path-dependent institutional processes with varying temporal and spatial horizons (cf. Pierson, 2004, 2005) in which no particular outcomes were guaranteed, but in terms of which some outcomes were more likely than others. Although the organisation of state power was expressed in the content of the PGDP, that power had to be understood as fractured across a range of state and non-state institutions, but with the state as the primary site of the contingent organisation of power. The provincial sphere of government faces particular constraints with the South African state, which has implications for its policy scope and the possibilities of policy challenge, even where wider social support is achieved.
- Full Text:
- Authors: Reynolds, John
- Date: 2014 , 2014-06-24
- Subjects: Community development -- South Africa -- Eastern Cape , South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3372 , http://hdl.handle.net/10962/d1013031
- Description: This thesis provides a provincial perspective on the limits of policy challenge within the post-apartheid South African state. This perspective is located in the Eastern Cape Province of South Africa, which is one of the poorest of the nine provinces into which the national territory was divided during the constitutional negotiations prior to the landmark democratic elections of 1994. The empirical foundation for this perspective is an analysis of the process of developing the Eastern Cape Provincial Growth and Development Plan 2004-2014 (PGDP), which took place in 2002-2004. Starting with a broader theoretical discussion, followed by a brief contextual analysis of the South African economy, the structure of the post-apartheid South African state, and key growth and development policies, the more detailed engagement with the PGDP process is undertaken. Drawing on Jessop’s (2008) strategic-relational approach, this thesis argues that the PGDP process arose within a particular spatio-temporal context where new opportunities for policy challenge were possible, but that such challenge had to be negotiated on a strategically selective terrain on which that challenge was neutralised. The PGDP process unfolded as a complex dialectic of agency and a range of path-dependent institutional processes with varying temporal and spatial horizons (cf. Pierson, 2004, 2005) in which no particular outcomes were guaranteed, but in terms of which some outcomes were more likely than others. Although the organisation of state power was expressed in the content of the PGDP, that power had to be understood as fractured across a range of state and non-state institutions, but with the state as the primary site of the contingent organisation of power. The provincial sphere of government faces particular constraints with the South African state, which has implications for its policy scope and the possibilities of policy challenge, even where wider social support is achieved.
- Full Text: