Identification of SANCDB compounds against G2019S and I2020T variants of leucine-rich repeat Kinase 2 (LRRK2) for the development of drugs against Parkinson’s Disease
- Authors: Baye, Bertha Cinthia
- Date: 2020
- Subjects: Antiparkinsonian agents , Parkinson's disease -- Treatment , Protein kinases , Parkinson's disease -- Chemotherapy , Molecules -- Models
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/138764 , vital:37671
- Description: Parkinson’s disease is a type of movement disorder that occurs when nerve cells in the brain stop producing dopamine. It is the second neurodegenerative disease affecting 1-2% of people above the ages of 65 years old. There is a worldwide prevalence of 7 to 10 million affected people of all cultures and race. Studies have shown that mutation that causes Parkinson’s disease result in increased kinase activity. The c.6055 G > A in exon 41 is the most prevalent LRRK2 variation which causes a substitution of glycine to serine in G2019S in the highly activated loop of its MAP kinase domain. The LRRK2 G2019S variant is the most common genetic determinant of Parkinson’s disease identified to date. This work focused on building accurate 3D models of the LRRK2 kinase domain, that were used for large-scale in silico docking against South African natural compounds from the South African Natural Compounds Database (SANCDB; https://sancdb.rubi.ru.ac.za/). Molecular docking was performed to identify compounds that formed interactions with the active site of the protein and had the lowest binding energy scores. Molecular dynamics simulations showed different movements of the protein-ligand complexes and behavioural difference of the wildtype and the variants, all three structures proved to be compact. Network analysis was done to study residue interactions, contact maps, dynamic cross correlations, average BC and average L were used to study the residue interactions and general residue contribution to the functioning of the protein..
- Full Text:
- Date Issued: 2020
- Authors: Baye, Bertha Cinthia
- Date: 2020
- Subjects: Antiparkinsonian agents , Parkinson's disease -- Treatment , Protein kinases , Parkinson's disease -- Chemotherapy , Molecules -- Models
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/138764 , vital:37671
- Description: Parkinson’s disease is a type of movement disorder that occurs when nerve cells in the brain stop producing dopamine. It is the second neurodegenerative disease affecting 1-2% of people above the ages of 65 years old. There is a worldwide prevalence of 7 to 10 million affected people of all cultures and race. Studies have shown that mutation that causes Parkinson’s disease result in increased kinase activity. The c.6055 G > A in exon 41 is the most prevalent LRRK2 variation which causes a substitution of glycine to serine in G2019S in the highly activated loop of its MAP kinase domain. The LRRK2 G2019S variant is the most common genetic determinant of Parkinson’s disease identified to date. This work focused on building accurate 3D models of the LRRK2 kinase domain, that were used for large-scale in silico docking against South African natural compounds from the South African Natural Compounds Database (SANCDB; https://sancdb.rubi.ru.ac.za/). Molecular docking was performed to identify compounds that formed interactions with the active site of the protein and had the lowest binding energy scores. Molecular dynamics simulations showed different movements of the protein-ligand complexes and behavioural difference of the wildtype and the variants, all three structures proved to be compact. Network analysis was done to study residue interactions, contact maps, dynamic cross correlations, average BC and average L were used to study the residue interactions and general residue contribution to the functioning of the protein..
- Full Text:
- Date Issued: 2020
A personality-based surveillance model for Facebook apps
- Authors: Van der Schyff, Karl Izak
- Date: 2020
- Subjects: Facebook (Electronic resource) , Electronic surveillance -- Psychological aspects , Online social networks -- Psychological aspects , Social media -- Psychological aspects , Personality
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145534 , vital:38447
- Description: The surveillance of data through the use of Facebook Apps is an ongoing and persistent problem that impacts millions of users. Nonetheless, limited research has been conducted investigating to what extent a Facebook user’s personality influences their awareness of such surveillance practices. Thus, to understand this situation better, the current study inductively developed four propositions from secondary data sources as part of a detailed content analysis. Spanning three search and analysis phases the content analysis led to the development of the research model. Guided by the propositions and research questions, a questionnaire was developed based on the relevant constructs prescribed by the Theory of Planned Behaviour. This questionnaire was used, and a total of 651 responses were collected from Facebook users over the age of 18 years old and residing in the United States of America. Primary data took place at both a univariate and multivariate level with a specific focus on the development of a structural model. Interpretation of the structural model revealed that out of all the Big Five personality traits, Conscientiousness exhibited the strongest relationship with information security awareness followed by Openness to Experience and Neuroticism, respectively. The results further indicated that the model constructs based on attitude, social norms and awareness significantly influenced the intended use of Facebook Apps. The study also contributes by indicating which personality traits are most vulnerable to Facebook App surveillance. For example, it was found that individuals high in Conscientiousness are the least vulnerable with individuals high in Extraversion being the most vulnerable. Since the results indicate that not all the personality traits are significantly related to the model constructs, additional factors may contribute to App surveillance in this context. Concerning this, factors such as user apathy, information privacy, privacy concerns, control and Facebook dependency are discussed as a means to argue why this might be the case.
- Full Text:
- Date Issued: 2020
- Authors: Van der Schyff, Karl Izak
- Date: 2020
- Subjects: Facebook (Electronic resource) , Electronic surveillance -- Psychological aspects , Online social networks -- Psychological aspects , Social media -- Psychological aspects , Personality
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145534 , vital:38447
- Description: The surveillance of data through the use of Facebook Apps is an ongoing and persistent problem that impacts millions of users. Nonetheless, limited research has been conducted investigating to what extent a Facebook user’s personality influences their awareness of such surveillance practices. Thus, to understand this situation better, the current study inductively developed four propositions from secondary data sources as part of a detailed content analysis. Spanning three search and analysis phases the content analysis led to the development of the research model. Guided by the propositions and research questions, a questionnaire was developed based on the relevant constructs prescribed by the Theory of Planned Behaviour. This questionnaire was used, and a total of 651 responses were collected from Facebook users over the age of 18 years old and residing in the United States of America. Primary data took place at both a univariate and multivariate level with a specific focus on the development of a structural model. Interpretation of the structural model revealed that out of all the Big Five personality traits, Conscientiousness exhibited the strongest relationship with information security awareness followed by Openness to Experience and Neuroticism, respectively. The results further indicated that the model constructs based on attitude, social norms and awareness significantly influenced the intended use of Facebook Apps. The study also contributes by indicating which personality traits are most vulnerable to Facebook App surveillance. For example, it was found that individuals high in Conscientiousness are the least vulnerable with individuals high in Extraversion being the most vulnerable. Since the results indicate that not all the personality traits are significantly related to the model constructs, additional factors may contribute to App surveillance in this context. Concerning this, factors such as user apathy, information privacy, privacy concerns, control and Facebook dependency are discussed as a means to argue why this might be the case.
- Full Text:
- Date Issued: 2020
But is it publishable? Mastering the MMed message
- Authors: A G Parrish , E S Grossman,
- Date: 202
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3353 , vital:43318 , http://www.samj.org.za/index.php/samj/article/view/13033
- Description: The research requirement for South African specialist registration offers opportunities and challenges. For some clinicians it may spark a lifelong interest in clinical investigation, while for many others it may provide a potential publication opportunity. Integrating the specific requirements of an MMed mini-dissertation with those of standard medical publications can be difficult for first-time authors and their supervisors; published guidance caters to full-length laboratory Master’s or doctoral research. We suggest that research is more likely to be publishable if it is locally relevant, has a clear clinical message and is coherently presented.
- Full Text:
- Date Issued: 202
- Authors: A G Parrish , E S Grossman,
- Date: 202
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3353 , vital:43318 , http://www.samj.org.za/index.php/samj/article/view/13033
- Description: The research requirement for South African specialist registration offers opportunities and challenges. For some clinicians it may spark a lifelong interest in clinical investigation, while for many others it may provide a potential publication opportunity. Integrating the specific requirements of an MMed mini-dissertation with those of standard medical publications can be difficult for first-time authors and their supervisors; published guidance caters to full-length laboratory Master’s or doctoral research. We suggest that research is more likely to be publishable if it is locally relevant, has a clear clinical message and is coherently presented.
- Full Text:
- Date Issued: 202
Effect of increasing fossil shell flour levels on digestive and metabolic utilization, health, body weight change and wool production, and quality in Dohne-Merino wethers
- Authors: Ikusika, Olusegun Oyebade
- Date: 2020
- Subjects: Merino sheep Sheep -- Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18465 , vital:42542
- Description: The study's broad objective was to assess growth performance, blood and parasitic profiles, wool parameters, methane emission, and nutritional status of Dohne-Merino wethers fed diets supplemented with varying levels of fossil shell flour. Twenty-four Dohne-Merino wethers, averagely weighing 20.0±1.50 kg, were divided into four groups and used in this study. The effects of varying inclusion levels of fossil shell flour (FSF) (0, 2, 4, and 6 %) on feed intake, water intake, nutrient digestibility, N-retention, hematobiochemical and parasitic profiles, body condition scores, feed preference, wool parameters and methane output were determined. The influence of FSF's varying inclusion levels on fermentation parameters, in vitro true digestibility, and relative feed values were also determined. Wethers fed with 4% FSF inclusion level diet showed the highest (P<0.05) values for dry matter intake, average daily weight gain, N retention, (Nitrogen retention) and apparent digestibility of crude protein (CP), Ether Extract (EE) and Ash 6 % (P < 0.05). The urinary N and fecal N were lowest in wethers fed 4% FSF inclusion level and highest in those fed on diets without FSF (P < 0.05). Water intake was highest in wethers fed 0% FSF diet, followed by those fed on 4% and lowest in 6% FSF (P< 0.05). There was a significant increase in white blood cell counts in wethers fed on a diet with 4% and 6% FSF inclusion levels from day 10 to 100 compared to wethers fed on a diet with 0% and 2% FSF (P <0.05). Red blood cell counts also increased significantly in wethers fed on a diet containing 4% FSF, but a slight increase in wethers with 6 % FSF diet, throughout the experimental period (P < 0.05). Blood urea was highest in wethers fed 0% FSF inclusion level and lowest in 6% at day 30 to day 100. Wethers on 4% FSF diet showed an increase in blood urea from day 30 to day 100 (P < 0.05) while wethers on 0% and 2% remained unchanged (P<0.05) during this period and not different (P > 0.05) from wethers on 4% FSF as well. The total protein concentration, albumin, total bilirubin, Na, K, glucose, cholesterol, and liver enzymes were normal for wethers. However, serum creatinine level was lower in wethers fed on 4% FSF than those on 0% FSF (P < 0.01). Haemonchus and Coccidian fecal egg counts were low in wethers fed diets with 2%, 4%, and 6 % FSF (P < 0.01) compared 11 with wethers fed with 0% FSF inclusion level during the same period. The body condition score of wethers fed on diets with 2%, 4%, and 6% FSF inclusion levels were higher than those on 0% (P < 0.05). Wool yield, staple length, the coefficient variation of the fibre diameter, and fibre of wethers fed on diets with FSF were higher than those without FSF (P < 0.05). The fibre diameter of the wethers fed on FSF supplemented diets was the same as those on 0 % FSF (P > 0.05). The wethers spent more time on FSF supplemented diets and consumed more feed compared to that without FSF supplemented (P < 0.05). The levels of FSF inclusion in the diet affected the enteric methane output (ppm-m), where 4 % FSF had the highest enteric methane output while wethers on 2 % FSF had the lowest methane output (P < 0.05). Resting wethers produced more methane (g/day) than those feeding or standing (P < 0.05). Increasing levels of FSF did not affect ruminal temperature and pH. Ammonia-N increased with increasing FSF except in wethers fed on a diet with 4% FSF (P < 0.01). The total molar concentrations of the wethers' volatile fatty acids decreased with increasing FSF levels (P > 0.05). The acetic propionic ratio of the wethers also decreased except at a 4% inclusion level. The in vitro true digestibility dry matter (IVTDDM), in vitro true digestibility neutral detergent fibre (IVTDNDF), and in vitro true digestibility acid detergent fibre (IVTDADF) of the wethers decreased up to 4% FSF inclusion but tended to increase at 6% inclusion. This study's result as one of the pioneer studies in Dohne-Marino wethers showed that FSF treatment has the potential to improve the nutritional status of the animal and the animal performance and wool quality. Health-wise, FSF decrease nematode population and boost animal immunity as seen in RBC and WBC counts. It also can play a major role in protecting the environment, as seen in its reduction in feacal and urinary nitrogen, which is heavily involved in environmental pollution. Result also confirmed that the best period to target for methane mitigation in ruminants is the resting period. In conclusion, the inclusion of FSF in the diet of Dohne-Merino wethers has the potential to improve the overall performance, with a 4% FSF inclusion level having optimal productivity. However, future research is required to investigate FSF's effect on meat quality, rumen microbial community, in-vivo digestibility, and milk production.
- Full Text:
- Date Issued: 2020
- Authors: Ikusika, Olusegun Oyebade
- Date: 2020
- Subjects: Merino sheep Sheep -- Quality
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/18465 , vital:42542
- Description: The study's broad objective was to assess growth performance, blood and parasitic profiles, wool parameters, methane emission, and nutritional status of Dohne-Merino wethers fed diets supplemented with varying levels of fossil shell flour. Twenty-four Dohne-Merino wethers, averagely weighing 20.0±1.50 kg, were divided into four groups and used in this study. The effects of varying inclusion levels of fossil shell flour (FSF) (0, 2, 4, and 6 %) on feed intake, water intake, nutrient digestibility, N-retention, hematobiochemical and parasitic profiles, body condition scores, feed preference, wool parameters and methane output were determined. The influence of FSF's varying inclusion levels on fermentation parameters, in vitro true digestibility, and relative feed values were also determined. Wethers fed with 4% FSF inclusion level diet showed the highest (P<0.05) values for dry matter intake, average daily weight gain, N retention, (Nitrogen retention) and apparent digestibility of crude protein (CP), Ether Extract (EE) and Ash 6 % (P < 0.05). The urinary N and fecal N were lowest in wethers fed 4% FSF inclusion level and highest in those fed on diets without FSF (P < 0.05). Water intake was highest in wethers fed 0% FSF diet, followed by those fed on 4% and lowest in 6% FSF (P< 0.05). There was a significant increase in white blood cell counts in wethers fed on a diet with 4% and 6% FSF inclusion levels from day 10 to 100 compared to wethers fed on a diet with 0% and 2% FSF (P <0.05). Red blood cell counts also increased significantly in wethers fed on a diet containing 4% FSF, but a slight increase in wethers with 6 % FSF diet, throughout the experimental period (P < 0.05). Blood urea was highest in wethers fed 0% FSF inclusion level and lowest in 6% at day 30 to day 100. Wethers on 4% FSF diet showed an increase in blood urea from day 30 to day 100 (P < 0.05) while wethers on 0% and 2% remained unchanged (P<0.05) during this period and not different (P > 0.05) from wethers on 4% FSF as well. The total protein concentration, albumin, total bilirubin, Na, K, glucose, cholesterol, and liver enzymes were normal for wethers. However, serum creatinine level was lower in wethers fed on 4% FSF than those on 0% FSF (P < 0.01). Haemonchus and Coccidian fecal egg counts were low in wethers fed diets with 2%, 4%, and 6 % FSF (P < 0.01) compared 11 with wethers fed with 0% FSF inclusion level during the same period. The body condition score of wethers fed on diets with 2%, 4%, and 6% FSF inclusion levels were higher than those on 0% (P < 0.05). Wool yield, staple length, the coefficient variation of the fibre diameter, and fibre of wethers fed on diets with FSF were higher than those without FSF (P < 0.05). The fibre diameter of the wethers fed on FSF supplemented diets was the same as those on 0 % FSF (P > 0.05). The wethers spent more time on FSF supplemented diets and consumed more feed compared to that without FSF supplemented (P < 0.05). The levels of FSF inclusion in the diet affected the enteric methane output (ppm-m), where 4 % FSF had the highest enteric methane output while wethers on 2 % FSF had the lowest methane output (P < 0.05). Resting wethers produced more methane (g/day) than those feeding or standing (P < 0.05). Increasing levels of FSF did not affect ruminal temperature and pH. Ammonia-N increased with increasing FSF except in wethers fed on a diet with 4% FSF (P < 0.01). The total molar concentrations of the wethers' volatile fatty acids decreased with increasing FSF levels (P > 0.05). The acetic propionic ratio of the wethers also decreased except at a 4% inclusion level. The in vitro true digestibility dry matter (IVTDDM), in vitro true digestibility neutral detergent fibre (IVTDNDF), and in vitro true digestibility acid detergent fibre (IVTDADF) of the wethers decreased up to 4% FSF inclusion but tended to increase at 6% inclusion. This study's result as one of the pioneer studies in Dohne-Marino wethers showed that FSF treatment has the potential to improve the nutritional status of the animal and the animal performance and wool quality. Health-wise, FSF decrease nematode population and boost animal immunity as seen in RBC and WBC counts. It also can play a major role in protecting the environment, as seen in its reduction in feacal and urinary nitrogen, which is heavily involved in environmental pollution. Result also confirmed that the best period to target for methane mitigation in ruminants is the resting period. In conclusion, the inclusion of FSF in the diet of Dohne-Merino wethers has the potential to improve the overall performance, with a 4% FSF inclusion level having optimal productivity. However, future research is required to investigate FSF's effect on meat quality, rumen microbial community, in-vivo digestibility, and milk production.
- Full Text:
- Date Issued: 2020
Cloud computing for competitive advantage: A case of rural SMEs in the Eastern Cape Province of South Africa
- Authors: Mpongwana , Mbongo Mhlanga
- Date: 2020
- Subjects: Cloud computing -- Economic aspects , Business enterprises -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/50415 , vital:42166
- Description: The emergence of new ICTs over the past decades has had a substantial impact on commerce and to societies in general. However, the high costs and the relevant skills and expertise that are associated with the implementation and maintenance of the latest ICTs impedes SMEs from taking full advantage of their use. The introduction and adoption of cloud computing has addressed some of these challenges for SMEs. Despite this, SMEs in rural South Africa have not fully adopted or realized the advantages of cloud computing, which could be owing to a number of factors.The aim of this study was to explore how rural SMEs in the Eastern Cape Province of South Africa can leverage on the capabilities of cloud computing for competitive advantage. The study adopted an interpretivist, quantitative approach to identifying the enablers and barriers of cloud computing adoption. The research population was defined as all the SMEs that operate outside of Buffalo City and Nelson Mandela Bay Metropolitan Municipalities. Convenience and snowball sampling techniques were used as non-probability sampling methods. Data was collected from the participants using a structured self-administered online questionnaire. The Technology-Organization-Environment framework was used as a basis in formulating the research theoretical framework, focusing on technological, organizational and environmental elements that could potentially influence adoption of cloud computing by rural SMEs. Microsoft Power BI was used to present demographic information as well as descriptive statistics for the factors included in the proposed research model. IBM SPSS 22 was used for correlation and linear regression analysis. The review of related literature revealed that access to markets, access to finance, inadequate public infrastructure and lack of skilled resources are some of the major challenges that rural SMEs face. This study found seven of the statistically examined factors to be significant predictors of cloud adoption by rural Eastern Cape SMEs. These are market demand, use of online-based marketing, having formal business plans, reliable electricity, awareness of SaaS, use of basic Internet-based services such as email and websites as well as Internet costs.
- Full Text:
- Date Issued: 2020
- Authors: Mpongwana , Mbongo Mhlanga
- Date: 2020
- Subjects: Cloud computing -- Economic aspects , Business enterprises -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/50415 , vital:42166
- Description: The emergence of new ICTs over the past decades has had a substantial impact on commerce and to societies in general. However, the high costs and the relevant skills and expertise that are associated with the implementation and maintenance of the latest ICTs impedes SMEs from taking full advantage of their use. The introduction and adoption of cloud computing has addressed some of these challenges for SMEs. Despite this, SMEs in rural South Africa have not fully adopted or realized the advantages of cloud computing, which could be owing to a number of factors.The aim of this study was to explore how rural SMEs in the Eastern Cape Province of South Africa can leverage on the capabilities of cloud computing for competitive advantage. The study adopted an interpretivist, quantitative approach to identifying the enablers and barriers of cloud computing adoption. The research population was defined as all the SMEs that operate outside of Buffalo City and Nelson Mandela Bay Metropolitan Municipalities. Convenience and snowball sampling techniques were used as non-probability sampling methods. Data was collected from the participants using a structured self-administered online questionnaire. The Technology-Organization-Environment framework was used as a basis in formulating the research theoretical framework, focusing on technological, organizational and environmental elements that could potentially influence adoption of cloud computing by rural SMEs. Microsoft Power BI was used to present demographic information as well as descriptive statistics for the factors included in the proposed research model. IBM SPSS 22 was used for correlation and linear regression analysis. The review of related literature revealed that access to markets, access to finance, inadequate public infrastructure and lack of skilled resources are some of the major challenges that rural SMEs face. This study found seven of the statistically examined factors to be significant predictors of cloud adoption by rural Eastern Cape SMEs. These are market demand, use of online-based marketing, having formal business plans, reliable electricity, awareness of SaaS, use of basic Internet-based services such as email and websites as well as Internet costs.
- Full Text:
- Date Issued: 2020
The use of ritual as physical and spiritual medium and its documentation in Buhlebezwe Siwani’s contemporary visual arts performance
- Authors: Lila, Philiswa
- Date: 2020
- Subjects: Arts and religion , Ritual -- South Africa , Performance art -- Religious aspects -- South Africa , Women performance artists -- South Africa , Siwani, Buhlebezwe, 1987-
- Language: English
- Type: text , Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/166160 , vital:41334
- Description: This thesis is motivated by my experience of Inzilo: Ngoba ngihlala kwabafileyo, a live performance by South African visual artist Buhlebezwe Siwani. The performance took place at Michaelis Galleries, University of Cape Town (UCT), as part of a group exhibition Between Subject and Object: human remains at the interface of art and science (2014), which accompanied the Medical Humanities in Africa Conference (from 28 – 29 August 2014). As an entry into my discussion, I describe how Siwani’s performance makes use of death and burial ritual in what seems to be an intention to make art that is (re)presenting an activity of reality to invade and control the sphere of feelings, emotions and a sense of ceremony that is dependent on both ritual and rites of the performance. I grapple with the fact that I experienced a ritual performance in a gallery space. Furthermore, I question how walking out of the performance I thought of the lines between art and/or life. The role of ritual in my thesis explores the symbolic meanings, powers and intentions of ritual rites in Africa. This reflection maps out historical locations that are relevant to the major debates, definitions, themes and the experiences of ritual as part of academic research. From Siwani’s practice as an artist and isangoma to other expressions in the fields of history, sociology, religion, feminism, to mention a few, my thesis is an enquiry that engages ritual and performance art theory and scholarship. Through a qualitative analysis, my methodology rejects a chronological, thematic and discipline centered research. Rather, I use a multidisciplinary approach based on critical visual analysis as knowledge creation in the visual arts, for example archives, documentation, performance, text, video, installation, painting, sculpture, etc. The findings suggests that the role of ritual in performance art is not a singular exploration, nor is it based on separating ritual and performance art. The results further reveal that ritual in performance art is not a reenactment of patterns and human behaviours, nor is the notion of reenactment used to denote the myriad meanings and functions of re-performing historical ritual events into performance art. Throughout, my thesis provides a focus that demonstrates the significance of how ritual in performance art has a profound subjective (personal or individual) and collective holistic way of serving human and spiritual needs, and that of creating an environment that is open to the content and context of art as it relates with traditional African religious practices, beliefs and knowledges. Focus is given to three major themes that make up the three chapters of my research: firstly, I reflect on death as personified by Siwani’s performance Inzilo: Ngoba ii ngihlala kwabafileyo and her role as isangoma. Here death is used to draw specific attention to the body in process of embodied presence and absence of physical and spiritual worlds. Secondly, drawing on Siwani’s concept of secrecy and boundaries of concealing and revealing rituals meanings and powers as isangoma, I question the role of secrets, which highlights the significance of bodies (human and natural sites of ritual) in ritual performance. Finally, the idea of a trace is explored. The intersecting use of a trace as the thinking-making-doing of ritual in performance articulates a connected thread that sets in motion the trace of ritual (installation, image and marked space pf ritual) as an afterlife that offers a continued space of processual ceremony for multiple effective encounters and movements..
- Full Text:
- Date Issued: 2020
- Authors: Lila, Philiswa
- Date: 2020
- Subjects: Arts and religion , Ritual -- South Africa , Performance art -- Religious aspects -- South Africa , Women performance artists -- South Africa , Siwani, Buhlebezwe, 1987-
- Language: English
- Type: text , Thesis , Masters , MFA
- Identifier: http://hdl.handle.net/10962/166160 , vital:41334
- Description: This thesis is motivated by my experience of Inzilo: Ngoba ngihlala kwabafileyo, a live performance by South African visual artist Buhlebezwe Siwani. The performance took place at Michaelis Galleries, University of Cape Town (UCT), as part of a group exhibition Between Subject and Object: human remains at the interface of art and science (2014), which accompanied the Medical Humanities in Africa Conference (from 28 – 29 August 2014). As an entry into my discussion, I describe how Siwani’s performance makes use of death and burial ritual in what seems to be an intention to make art that is (re)presenting an activity of reality to invade and control the sphere of feelings, emotions and a sense of ceremony that is dependent on both ritual and rites of the performance. I grapple with the fact that I experienced a ritual performance in a gallery space. Furthermore, I question how walking out of the performance I thought of the lines between art and/or life. The role of ritual in my thesis explores the symbolic meanings, powers and intentions of ritual rites in Africa. This reflection maps out historical locations that are relevant to the major debates, definitions, themes and the experiences of ritual as part of academic research. From Siwani’s practice as an artist and isangoma to other expressions in the fields of history, sociology, religion, feminism, to mention a few, my thesis is an enquiry that engages ritual and performance art theory and scholarship. Through a qualitative analysis, my methodology rejects a chronological, thematic and discipline centered research. Rather, I use a multidisciplinary approach based on critical visual analysis as knowledge creation in the visual arts, for example archives, documentation, performance, text, video, installation, painting, sculpture, etc. The findings suggests that the role of ritual in performance art is not a singular exploration, nor is it based on separating ritual and performance art. The results further reveal that ritual in performance art is not a reenactment of patterns and human behaviours, nor is the notion of reenactment used to denote the myriad meanings and functions of re-performing historical ritual events into performance art. Throughout, my thesis provides a focus that demonstrates the significance of how ritual in performance art has a profound subjective (personal or individual) and collective holistic way of serving human and spiritual needs, and that of creating an environment that is open to the content and context of art as it relates with traditional African religious practices, beliefs and knowledges. Focus is given to three major themes that make up the three chapters of my research: firstly, I reflect on death as personified by Siwani’s performance Inzilo: Ngoba ii ngihlala kwabafileyo and her role as isangoma. Here death is used to draw specific attention to the body in process of embodied presence and absence of physical and spiritual worlds. Secondly, drawing on Siwani’s concept of secrecy and boundaries of concealing and revealing rituals meanings and powers as isangoma, I question the role of secrets, which highlights the significance of bodies (human and natural sites of ritual) in ritual performance. Finally, the idea of a trace is explored. The intersecting use of a trace as the thinking-making-doing of ritual in performance articulates a connected thread that sets in motion the trace of ritual (installation, image and marked space pf ritual) as an afterlife that offers a continued space of processual ceremony for multiple effective encounters and movements..
- Full Text:
- Date Issued: 2020
Photocatalysis of 4-chloro and 4-nonylphenols using novel symmetric phthalocyanines and asymmetric porphyrin supported on polyacrylonitrite nanofibres
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
- Full Text:
- Date Issued: 2020
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
- Full Text:
- Date Issued: 2020
Synthesis, photophysicochemical properties and photodynamic therapy activities of indium and zinc phthalocyanines when incorporated into Pluronic polymer micelles
- Authors: Motloung, Banele Mike
- Date: 2020
- Subjects: Indium , Zinc , Phthalocyanines , Polymers , Photochemotherapy , Micelles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167529 , vital:41489
- Description: This thesis reports on the syntheses, photophysicochemical properties and photodynamic therapy activities of symmetrical metallophthalocyanines (MPcs) when alone or when incorporated into Pluronic polymer micelles. The Pcs contain either zinc or indium as central metals and have phenyldiazenylphenoxy, pyridine-2-yloxy and benzo[d]thiazol-2-ylthio as ring substituents. Spectroscopic and microscopic techniques were used to confirm the formation MPcs with micelles. The photophysics and photochemistry of the Pcs were assessed when alone and with micelles. All the studied Pcs showed good photophysicochemical behavior with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yields. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy atom effect obtained from the former. The in vitro dark cytotoxicity and photodynamic therapy of the Pc complexes and conjugates against MCF7 cells was tested. All studied Pc complexes alone and with micelles showed minimum dark toxicity making them applicable for PDT. All complexes displayed good phototoxicity < 50% cell viability (except for complex 2 > 50% cell viability) at concentrations ≤100 μg/mL, however the conjugates showed < 45% cell viability at concentrations ≤ 100 μg/mL, probably due to the small micellar size and EPR effect. The findings from this work show the importance of incorporating photosensitizers such as phthalocyanines into Pluronic polymers micelles and making them water soluble and ultimately improving their photodynamic effect.
- Full Text:
- Date Issued: 2020
- Authors: Motloung, Banele Mike
- Date: 2020
- Subjects: Indium , Zinc , Phthalocyanines , Polymers , Photochemotherapy , Micelles
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167529 , vital:41489
- Description: This thesis reports on the syntheses, photophysicochemical properties and photodynamic therapy activities of symmetrical metallophthalocyanines (MPcs) when alone or when incorporated into Pluronic polymer micelles. The Pcs contain either zinc or indium as central metals and have phenyldiazenylphenoxy, pyridine-2-yloxy and benzo[d]thiazol-2-ylthio as ring substituents. Spectroscopic and microscopic techniques were used to confirm the formation MPcs with micelles. The photophysics and photochemistry of the Pcs were assessed when alone and with micelles. All the studied Pcs showed good photophysicochemical behavior with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yields. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy atom effect obtained from the former. The in vitro dark cytotoxicity and photodynamic therapy of the Pc complexes and conjugates against MCF7 cells was tested. All studied Pc complexes alone and with micelles showed minimum dark toxicity making them applicable for PDT. All complexes displayed good phototoxicity < 50% cell viability (except for complex 2 > 50% cell viability) at concentrations ≤100 μg/mL, however the conjugates showed < 45% cell viability at concentrations ≤ 100 μg/mL, probably due to the small micellar size and EPR effect. The findings from this work show the importance of incorporating photosensitizers such as phthalocyanines into Pluronic polymers micelles and making them water soluble and ultimately improving their photodynamic effect.
- Full Text:
- Date Issued: 2020
Market timing and portfolio returns: an empirical analysis of the potential profitability of buy-sell strategies, based on South African equities 2009-2018
- Authors: Mulweli, Ramulongo
- Date: 2020
- Subjects: Johannesburg Stock Exchange , Stocks -- Charts, diagrams, etc. , Investment analysis -- South Africa , Stocks -- South Africa , Stocks -- South Africa -- Cast studies
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/144487 , vital:38350
- Description: South Africa’s financial markets have become larger and more complex over recent decades. The number of market participants who are using technical analysis techniques to predict the market’s movement has been growing rapidly. This research aims to investigate if historical share prices can be used when forecasting the market’s direction and to examine the profitability of the Japanese candlestick patterns. The study is based on ten companies selected from the JSE top 40 2019 composition. These are Aspen Pharmacy Holding, Capitec Bank Holding LTD, Discovery LTD, Kumba Iron Ore LTD, Mondi PLC, Mr. Price Group LTD, MTN Group LTD, Naspers LTD, SASOL LTD, and Shoprite Holdings LTD. These were selected from the JSE top 40 based on market capitalization and sector. This research analyzes eight candlestick reversal patterns; four are bullish patterns namely: doji star, hammer, bullish engulfing and the piercing lines and the other four are bearish patterns namely: shooting star, hanging man, bearish engulfing and the dark cloud cover. The ARCH and GARCH models are used to test for correlation between past share prices and future share prices and the binomial test and the mean return calculations were used to test the profitability of candlestick patterns. The sample is from Thomson DataStream 2019 and IRESS SA 2019 and covers ten years with 2496 observations starting from 02 January 2009 to 31 December 2018. The findings from the ARCH and GARCH tests revealed that there is a serial correlation between the returns from the previous day and the returns for the current day. The results from the mean returns and the binomial tests show strong evidence that the shooting star, hanging man, bearish engulfing and the bulling engulfing are statistically significant in predicting the share price movements. On the other hand, there was no evidence that the dark cloud cover, piercing lines, and the bullish doji can predict share price movements. Additionally, further studies on this topic could be improved by adding different candlestick patterns and the total number of companies analyzed. The results could also be improved by analyzing the candlestick reversal patterns when they are used with other trading rules such as support resistance levels and oscillators.
- Full Text:
- Date Issued: 2020
- Authors: Mulweli, Ramulongo
- Date: 2020
- Subjects: Johannesburg Stock Exchange , Stocks -- Charts, diagrams, etc. , Investment analysis -- South Africa , Stocks -- South Africa , Stocks -- South Africa -- Cast studies
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/144487 , vital:38350
- Description: South Africa’s financial markets have become larger and more complex over recent decades. The number of market participants who are using technical analysis techniques to predict the market’s movement has been growing rapidly. This research aims to investigate if historical share prices can be used when forecasting the market’s direction and to examine the profitability of the Japanese candlestick patterns. The study is based on ten companies selected from the JSE top 40 2019 composition. These are Aspen Pharmacy Holding, Capitec Bank Holding LTD, Discovery LTD, Kumba Iron Ore LTD, Mondi PLC, Mr. Price Group LTD, MTN Group LTD, Naspers LTD, SASOL LTD, and Shoprite Holdings LTD. These were selected from the JSE top 40 based on market capitalization and sector. This research analyzes eight candlestick reversal patterns; four are bullish patterns namely: doji star, hammer, bullish engulfing and the piercing lines and the other four are bearish patterns namely: shooting star, hanging man, bearish engulfing and the dark cloud cover. The ARCH and GARCH models are used to test for correlation between past share prices and future share prices and the binomial test and the mean return calculations were used to test the profitability of candlestick patterns. The sample is from Thomson DataStream 2019 and IRESS SA 2019 and covers ten years with 2496 observations starting from 02 January 2009 to 31 December 2018. The findings from the ARCH and GARCH tests revealed that there is a serial correlation between the returns from the previous day and the returns for the current day. The results from the mean returns and the binomial tests show strong evidence that the shooting star, hanging man, bearish engulfing and the bulling engulfing are statistically significant in predicting the share price movements. On the other hand, there was no evidence that the dark cloud cover, piercing lines, and the bullish doji can predict share price movements. Additionally, further studies on this topic could be improved by adding different candlestick patterns and the total number of companies analyzed. The results could also be improved by analyzing the candlestick reversal patterns when they are used with other trading rules such as support resistance levels and oscillators.
- Full Text:
- Date Issued: 2020
The development of a framework to facilitate an increase level of self employment mongst the rural youth by promoting increased level of entrepreneurial intent
- Authors: Lindoor, Jillian
- Date: 2020
- Subjects: Youth-- Employment -- South Africa -- Eastern Cape , Rural youth -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/49878 , vital:41812
- Description: Natural resources and unique livelihoods within rural areas could be transformed into investments that would attract affluent urban groups and benefit the wider community,reduce unemployment and create self-employment among the youth. However limited employment opportunities, ongoing failure of local development projects, low level of self-acknowledge conviction amongst the rural youth to set up new business ventures is low exists. These issues that serve as the motivation for this research, are evident in the Dr Beyers Naude Local Municipality (BNLM) in the Eastern Cape of South Africa. These issues increases poverty, alcohol and substance abuse. It is important to find a solution to the problem and develop the local economy, increase employment, reduce poverty and assist in contributing to the millennium goals as set out by the United Nations. The research objective of the study is therefore to investigate what methods can be implemented to facilitate an increase in the level of self-employment amongst the rural youth by promoting an increased level of entrepreneurial intent.
- Full Text:
- Date Issued: 2020
- Authors: Lindoor, Jillian
- Date: 2020
- Subjects: Youth-- Employment -- South Africa -- Eastern Cape , Rural youth -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10948/49878 , vital:41812
- Description: Natural resources and unique livelihoods within rural areas could be transformed into investments that would attract affluent urban groups and benefit the wider community,reduce unemployment and create self-employment among the youth. However limited employment opportunities, ongoing failure of local development projects, low level of self-acknowledge conviction amongst the rural youth to set up new business ventures is low exists. These issues that serve as the motivation for this research, are evident in the Dr Beyers Naude Local Municipality (BNLM) in the Eastern Cape of South Africa. These issues increases poverty, alcohol and substance abuse. It is important to find a solution to the problem and develop the local economy, increase employment, reduce poverty and assist in contributing to the millennium goals as set out by the United Nations. The research objective of the study is therefore to investigate what methods can be implemented to facilitate an increase in the level of self-employment amongst the rural youth by promoting an increased level of entrepreneurial intent.
- Full Text:
- Date Issued: 2020
Investigating the relationship between Heat Shock Proteins and HIV Transactivator of Transcription
- Authors: Flax, Lili Marie
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163307 , vital:41027
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Flax, Lili Marie
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163307 , vital:41027
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
The effects of directed financing on growth and performance of smallholder farmers in the Western Cape Province
- Authors: Deliwe, Peliwe
- Date: 2020
- Subjects: Farms, Small -- South Africa -- Western Cape -- Finance
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/47705 , vital:40328
- Description: Agriculture is of great significance in the South African economy as it contributes over 3% of the country’s Gross Domestic Product (GDP), and accounting for more than 10% of the formal sector employment. Although agriculture is seasonal, it is regarded as an intensive employment sector which plays a critical role on promoting empowerment and improving food security. The smallholder farming sector is the result of policies targeting the participation of previously disadvantaged individual (PDI’s) in the food economy, particularly through land use and ownership (Isdardi, Jordaan & van Schalkwyk, 2008: 1). Smallholder farmers are neither commercial farmers nor subsistence in nature but have become the focus of government’s efforts to achieve transformation within the broad agricultural sector.
- Full Text:
- Date Issued: 2020
- Authors: Deliwe, Peliwe
- Date: 2020
- Subjects: Farms, Small -- South Africa -- Western Cape -- Finance
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: http://hdl.handle.net/10948/47705 , vital:40328
- Description: Agriculture is of great significance in the South African economy as it contributes over 3% of the country’s Gross Domestic Product (GDP), and accounting for more than 10% of the formal sector employment. Although agriculture is seasonal, it is regarded as an intensive employment sector which plays a critical role on promoting empowerment and improving food security. The smallholder farming sector is the result of policies targeting the participation of previously disadvantaged individual (PDI’s) in the food economy, particularly through land use and ownership (Isdardi, Jordaan & van Schalkwyk, 2008: 1). Smallholder farmers are neither commercial farmers nor subsistence in nature but have become the focus of government’s efforts to achieve transformation within the broad agricultural sector.
- Full Text:
- Date Issued: 2020
A trait-based approach to identify indicators for measuring rocky reef ecosystem condition in South Africa
- Authors: Smit, Kaylee
- Date: 2020
- Subjects: Environmental management -- Evaluation , Environmental monitoring -- Methodology Marine ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49292 , vital:41618
- Description: An important yet challenging task for effective ecosystem-based management of marine ecosystems is the reliable measurement and monitoring of changes in ecosystem condition. In South Africa, the National Biodiversity Assessment (NBA) has relied on cumulative pressure mapping, based on the calculation of cumulative impact scores, as a proxy for measures of marine ecosystem condition. While this method is practical for broad scale assessments where ecological data are lacking, there is a need to groundtruth this approach at local scales using in-situ data. The aim of this thesis was to identify potential indicators that can be used to measure the ecosystem condition of subtidal rocky reefs on the East coast of South Africa to groundtruth national pressure-based condition assessments. This thesis constituted the first attempt to conduct a comprehensive assessment of rocky reef ecosystem condition to validate national pressure-based assessments in South Africa. Based on a comprehensive literature review, a traits-based approach was selected to ensure that ecosystem structure and function were included in condition measurements. Fish and benthic community data were collected using baited remote underwater stereo-video systems (144 video samples) from the Natal Shelf ecoregion. Sampling spanned a gradient of low to high human pressures, which incorporated an effective Marine Protected Area (to define reference conditions), as well as areas exposed to intermediate levels of human pressures and a highly impacted area offshore of a large metropolitan port city. Structural and functional indicators were compared among localities and suitable functional indicators were aggregated into multimetric indices (MMIs) to provide an integrated measurement of ecosystem condition. Approximately 840 benthic biota and 10 400 fish (representing 176 identified fish species) were counted. Results showed that functional indicators, particularly size-based ones, were more effective at detecting changes in ecosystem condition compared with structural indicators based on taxonomy. Reefs in good ecological condition had a higher biomass of target species and a higher proportion of large predatory fish with more adults, compared with impacted areas. Benthic communities, however, appeared less responsive to cumulative pressures. The MMIs, using fish and benthic community data, were used to compare condition categories with those from the NBA. Results showed that the pressure-based assessments provided a reasonable proxy of broad patterns of rocky reef ecosystem condition. However, fine-scale discrepancies between results from the data-driven approach versus the proxy method suggested that broad-scale proxies might overestimate condition in some areas and underestimate it in others. To build on these results, the applicability of structural and functional indicators and MMIs were tested using an independent stereo-BRUVs dataset from the Agulhas Shelf ecoregion. Findings showed that not all MPAs were in good ecological condition compared with adjacent impacted areas, as was estimated by the NBA. However, there is a need to improve the quality of trait data and to test indicators and indices in other ecoregions, ecosystem types and in response to a broader range of improved pressure data. Furthermore, there is a need to apply innovative research to guide the calculation of thresholds for condition categories to advance condition assessments.
- Full Text:
- Date Issued: 2020
- Authors: Smit, Kaylee
- Date: 2020
- Subjects: Environmental management -- Evaluation , Environmental monitoring -- Methodology Marine ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49292 , vital:41618
- Description: An important yet challenging task for effective ecosystem-based management of marine ecosystems is the reliable measurement and monitoring of changes in ecosystem condition. In South Africa, the National Biodiversity Assessment (NBA) has relied on cumulative pressure mapping, based on the calculation of cumulative impact scores, as a proxy for measures of marine ecosystem condition. While this method is practical for broad scale assessments where ecological data are lacking, there is a need to groundtruth this approach at local scales using in-situ data. The aim of this thesis was to identify potential indicators that can be used to measure the ecosystem condition of subtidal rocky reefs on the East coast of South Africa to groundtruth national pressure-based condition assessments. This thesis constituted the first attempt to conduct a comprehensive assessment of rocky reef ecosystem condition to validate national pressure-based assessments in South Africa. Based on a comprehensive literature review, a traits-based approach was selected to ensure that ecosystem structure and function were included in condition measurements. Fish and benthic community data were collected using baited remote underwater stereo-video systems (144 video samples) from the Natal Shelf ecoregion. Sampling spanned a gradient of low to high human pressures, which incorporated an effective Marine Protected Area (to define reference conditions), as well as areas exposed to intermediate levels of human pressures and a highly impacted area offshore of a large metropolitan port city. Structural and functional indicators were compared among localities and suitable functional indicators were aggregated into multimetric indices (MMIs) to provide an integrated measurement of ecosystem condition. Approximately 840 benthic biota and 10 400 fish (representing 176 identified fish species) were counted. Results showed that functional indicators, particularly size-based ones, were more effective at detecting changes in ecosystem condition compared with structural indicators based on taxonomy. Reefs in good ecological condition had a higher biomass of target species and a higher proportion of large predatory fish with more adults, compared with impacted areas. Benthic communities, however, appeared less responsive to cumulative pressures. The MMIs, using fish and benthic community data, were used to compare condition categories with those from the NBA. Results showed that the pressure-based assessments provided a reasonable proxy of broad patterns of rocky reef ecosystem condition. However, fine-scale discrepancies between results from the data-driven approach versus the proxy method suggested that broad-scale proxies might overestimate condition in some areas and underestimate it in others. To build on these results, the applicability of structural and functional indicators and MMIs were tested using an independent stereo-BRUVs dataset from the Agulhas Shelf ecoregion. Findings showed that not all MPAs were in good ecological condition compared with adjacent impacted areas, as was estimated by the NBA. However, there is a need to improve the quality of trait data and to test indicators and indices in other ecoregions, ecosystem types and in response to a broader range of improved pressure data. Furthermore, there is a need to apply innovative research to guide the calculation of thresholds for condition categories to advance condition assessments.
- Full Text:
- Date Issued: 2020
The impact of the slum upgrading approach on the livelihoods of scheme participants in Uganda : using the sustainable livelihoods framework
- Authors: Karungi, Doreen
- Date: 2020
- Subjects: Slums -- Public welfare -- Uganda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48412 , vital:40874
- Description: International and local agencies recommend implementing slum upgrading projects in slum areas for slum improvement. However, with no model or guiding principles provided to slum upgrading project implementers on how to upgrade a slum, slum clearance and redevelopment are implemented rather than slum upgrading consequently projects fail to benefit the target group, slum dwellers. Data collection, took place in five areas in Uganda that implemented slum upgrading. In depth interviews were held with project beneficiaries, local council officials and association executives, and government officials at the Ministry of Lands, Housing and Urban Development. Field observation, and document analysis was carried out. Data analysis involved the use of the sustainable livelihoods framework. This study demonstrates that the slum upgrading approach adopted in Uganda exhibited low sustainability and undercut the sustainability of livelihoods of scheme participants. Slum dwellers faced vulnerabilities from loss of land, characterized by rights based actions resulting in minimal to no compensation or eviction and loss of existing livelihoods. Slum upgrading projects introduced new livelihood opportunities that were too few for slum dwellers, were not sustainable and ended during or with project implementation, leaving beneficiaries without employment or income opportunities. Increased vulnerability was observed as slum dwellers that did not benefit from the project were displaced to worse conditions while slum dwellers that benefitted, project beneficiaries remained poor and in debt, with project loans to repay. Although project beneficiaries were provided with access to assets, they were unable to draw on these to build their livelihoods. Some beneficiaries sold plots and project houses allocated to them and moved to adjacent slums, where they lived in worse conditions. At the time of the current research, good quality houses in the slum upgrading areas did not belong to the original beneficiaries old dilapidated structures were occupied by project beneficiaries. This study shows that income earning activities carried out at the time of the study were similar to those carried out prior to the introduction of slum upgrading in project areas and were destroyed during project implementation or banned by implementers. These activities were however carried out in incomplete houses, vacant plots, temporary structures in project areas and in adjacent swamps and forest. Generally, after completion of slum upgrading projects, project areas, adjacent swamps and forest were characterized by haphazard developments including: rentals, informal businesses, farming, brewing and distilling local alcohol used by beneficiaries to derive livelihoods, in other words, slums were recreated, a problem slum upgrading project implementers set out to solve - except in one study area where the project was implemented differently as a result of persist rights based actions.
- Full Text:
- Date Issued: 2020
- Authors: Karungi, Doreen
- Date: 2020
- Subjects: Slums -- Public welfare -- Uganda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/48412 , vital:40874
- Description: International and local agencies recommend implementing slum upgrading projects in slum areas for slum improvement. However, with no model or guiding principles provided to slum upgrading project implementers on how to upgrade a slum, slum clearance and redevelopment are implemented rather than slum upgrading consequently projects fail to benefit the target group, slum dwellers. Data collection, took place in five areas in Uganda that implemented slum upgrading. In depth interviews were held with project beneficiaries, local council officials and association executives, and government officials at the Ministry of Lands, Housing and Urban Development. Field observation, and document analysis was carried out. Data analysis involved the use of the sustainable livelihoods framework. This study demonstrates that the slum upgrading approach adopted in Uganda exhibited low sustainability and undercut the sustainability of livelihoods of scheme participants. Slum dwellers faced vulnerabilities from loss of land, characterized by rights based actions resulting in minimal to no compensation or eviction and loss of existing livelihoods. Slum upgrading projects introduced new livelihood opportunities that were too few for slum dwellers, were not sustainable and ended during or with project implementation, leaving beneficiaries without employment or income opportunities. Increased vulnerability was observed as slum dwellers that did not benefit from the project were displaced to worse conditions while slum dwellers that benefitted, project beneficiaries remained poor and in debt, with project loans to repay. Although project beneficiaries were provided with access to assets, they were unable to draw on these to build their livelihoods. Some beneficiaries sold plots and project houses allocated to them and moved to adjacent slums, where they lived in worse conditions. At the time of the current research, good quality houses in the slum upgrading areas did not belong to the original beneficiaries old dilapidated structures were occupied by project beneficiaries. This study shows that income earning activities carried out at the time of the study were similar to those carried out prior to the introduction of slum upgrading in project areas and were destroyed during project implementation or banned by implementers. These activities were however carried out in incomplete houses, vacant plots, temporary structures in project areas and in adjacent swamps and forest. Generally, after completion of slum upgrading projects, project areas, adjacent swamps and forest were characterized by haphazard developments including: rentals, informal businesses, farming, brewing and distilling local alcohol used by beneficiaries to derive livelihoods, in other words, slums were recreated, a problem slum upgrading project implementers set out to solve - except in one study area where the project was implemented differently as a result of persist rights based actions.
- Full Text:
- Date Issued: 2020
Analytical evaluation of the effect of aggregate variation on Asphalt Mixture Properties
- Authors: Van Eck, Elandre
- Date: 2020
- Subjects: Aggregates (Building materials)
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49639 , vital:41743
- Description: This research study aimed to conduct an analytical evaluation of the effect of aggregate grading on the properties of asphalt mixtures. This was achieved by obtaining asphalt mix designs from approved civil engineering organisations and determining the relationship between the aggregate grading and the corresponding properties of the asphalt mix designs.
- Full Text: false
- Date Issued: 2020
- Authors: Van Eck, Elandre
- Date: 2020
- Subjects: Aggregates (Building materials)
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49639 , vital:41743
- Description: This research study aimed to conduct an analytical evaluation of the effect of aggregate grading on the properties of asphalt mixtures. This was achieved by obtaining asphalt mix designs from approved civil engineering organisations and determining the relationship between the aggregate grading and the corresponding properties of the asphalt mix designs.
- Full Text: false
- Date Issued: 2020
The effect of age and maturation on anthropometric characteristics and physical abilities of youth South African footballers
- Authors: De Beer, Ashley
- Date: 2020
- Subjects: Soccer -- Physiologial aspects , Soccer players -- South Africa -- Makhanda -- Physiology , Soccer players -- South Africa -- Makhanda -- Psychophysiology , Makana Local Football Association (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/141222 , vital:37954
- Description: Currently there is limited research investigating the football related abilities of youth South African individuals. Populations from North and South America, Europe and Asia have been extensively covered in terms of their anthropometric characteristics, physical abilities, technical competency, tactical understanding as well as various personality traits. In describing these details, and especially how each is affected during the ageing and pubertal process, a more informed understanding of the talent development systems is created. A holistic approach to talent development is required to effectively and efficiently produce elite level footballers. An important consideration is the unique socio-economic environment many youth footballers experience which may impact on the talent development process. The present study therefore sought to quantify the anthropometric characteristics and the physical ability level of youth South African footballers from Local Football Association in Makhanda in the Sarah Baartman Region of the Eastern Cape province. In order to achieve this a two-factorial design was used with age and maturity status as independent variables. Anthropometric characteristics were tested by finding the height, weight, body mass index and total fat percentage of participants. Physical ability was determined by results for aerobic capacity, power, acceleration, speed and agility. All tests were football specific and had been widely used in a variety of footballing studies. Additional demographic and socio-economic information was also recorded. A total of 136 participants were placed in their respective Under 11, 13, 15 or Under 19 age groups, while the maturity status of 96 participants were stratified into five distinct categories. Statistical analyses was conducted using p-value significance, with appropriate Tukey post-hoc tests administered when necessary, while effect sizes were calculated using Cohen’s d. Significant changes and practical effect sizes were present for nearly all dependent variables when either stratified by age or by maturity. Total fat percentage was the only dependent variable which was not influenced by either age or maturity. Age and maturity effect sizes for total body fat percentage indicated practical changes present which did not occur during statistical analysis. The present results indicate poor values when compared to normative data or that of other football playing study populations. Further longitudinal research is required to better understand individual growth rates for youth South African footballers, particularly from the Makana region. Implications of the thesis may determine long term development pathways, while the delayed maturity rate is a critical finding which needs to be further researched.
- Full Text:
- Date Issued: 2020
- Authors: De Beer, Ashley
- Date: 2020
- Subjects: Soccer -- Physiologial aspects , Soccer players -- South Africa -- Makhanda -- Physiology , Soccer players -- South Africa -- Makhanda -- Psychophysiology , Makana Local Football Association (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/141222 , vital:37954
- Description: Currently there is limited research investigating the football related abilities of youth South African individuals. Populations from North and South America, Europe and Asia have been extensively covered in terms of their anthropometric characteristics, physical abilities, technical competency, tactical understanding as well as various personality traits. In describing these details, and especially how each is affected during the ageing and pubertal process, a more informed understanding of the talent development systems is created. A holistic approach to talent development is required to effectively and efficiently produce elite level footballers. An important consideration is the unique socio-economic environment many youth footballers experience which may impact on the talent development process. The present study therefore sought to quantify the anthropometric characteristics and the physical ability level of youth South African footballers from Local Football Association in Makhanda in the Sarah Baartman Region of the Eastern Cape province. In order to achieve this a two-factorial design was used with age and maturity status as independent variables. Anthropometric characteristics were tested by finding the height, weight, body mass index and total fat percentage of participants. Physical ability was determined by results for aerobic capacity, power, acceleration, speed and agility. All tests were football specific and had been widely used in a variety of footballing studies. Additional demographic and socio-economic information was also recorded. A total of 136 participants were placed in their respective Under 11, 13, 15 or Under 19 age groups, while the maturity status of 96 participants were stratified into five distinct categories. Statistical analyses was conducted using p-value significance, with appropriate Tukey post-hoc tests administered when necessary, while effect sizes were calculated using Cohen’s d. Significant changes and practical effect sizes were present for nearly all dependent variables when either stratified by age or by maturity. Total fat percentage was the only dependent variable which was not influenced by either age or maturity. Age and maturity effect sizes for total body fat percentage indicated practical changes present which did not occur during statistical analysis. The present results indicate poor values when compared to normative data or that of other football playing study populations. Further longitudinal research is required to better understand individual growth rates for youth South African footballers, particularly from the Makana region. Implications of the thesis may determine long term development pathways, while the delayed maturity rate is a critical finding which needs to be further researched.
- Full Text:
- Date Issued: 2020
Detection and effects of selected pharmaceutical compounds from selected water bodies in the Eastern Cape Province, South Africa
- Authors: Setshedi, Koketso Josinah
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177074 , vital:42788
- Description: Theses embargoed. Release date March 2023. , Thesis (MSc) -- Faculty of Pharmacy, Department of Pharmaceutical Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Setshedi, Koketso Josinah
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177074 , vital:42788
- Description: Theses embargoed. Release date March 2023. , Thesis (MSc) -- Faculty of Pharmacy, Department of Pharmaceutical Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
BEd foundation phase fourth year student teachers’ self-efficacy beliefs towards teaching mathematics and the self-reported factors that influence these self-efficacy beliefs
- Authors: Harrison, Chloe
- Date: 2020
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Mathematics teachers -- Training of -- South Africa , Educational evaluation -- South Africa , Student teachers -- Training of -- South Africa , Student teachers -- Rating of -- South Africa , Social cognitive theory , Self-efficacy
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/147004 , vital:38584
- Description: The underperformance of mathematics teaching and learning is a pressing concern in South Africa. Many foundation phase in-service teachers show inadequate mathematics content knowledge which creates barriers to their learners acquiring adequate mathematics skills. Teacher training programmes offer a key opportunity to improve the instructional practices of teachers at foundation phase level. In order to improve the teaching skills of in-service teachers, one focus must be on teacher training programmes. Unfortunately, there are many foundation phase student teachers who are leaving the profession within the first few years of teaching reportedly due to low levels of motivation. This research investigates the self-efficacy beliefs of pre-service student teachers. It also focuses on foundation phase student teachers as they experience significant challenges to their self-efficacy beliefs in mathematics and mathematics teaching. Self-efficacy is the key theory of the study. It stems from Bandura’s social cognitive theory and is an individual’s judgments about their capabilities, skills and perceived performance. This qualitative research adopts an interpretivist approach which seeks to identify Bed foundation phase fourth year student teachers’ self-efficacy beliefs towards teaching mathematics and the self-reported factors influencing such beliefs. This research found that BEd foundation phase fourth year student teachers have low self-efficacy beliefs towards teaching mathematics. The purpose of this research is to raise awareness of the BEd student teachers’ low self-efficacy beliefs towards teaching mathematics. The results from this research will provide a platform for future intervention research, as well as potentially influencing student teacher training programmes.
- Full Text:
- Date Issued: 2020
- Authors: Harrison, Chloe
- Date: 2020
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Mathematics teachers -- Training of -- South Africa , Educational evaluation -- South Africa , Student teachers -- Training of -- South Africa , Student teachers -- Rating of -- South Africa , Social cognitive theory , Self-efficacy
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/147004 , vital:38584
- Description: The underperformance of mathematics teaching and learning is a pressing concern in South Africa. Many foundation phase in-service teachers show inadequate mathematics content knowledge which creates barriers to their learners acquiring adequate mathematics skills. Teacher training programmes offer a key opportunity to improve the instructional practices of teachers at foundation phase level. In order to improve the teaching skills of in-service teachers, one focus must be on teacher training programmes. Unfortunately, there are many foundation phase student teachers who are leaving the profession within the first few years of teaching reportedly due to low levels of motivation. This research investigates the self-efficacy beliefs of pre-service student teachers. It also focuses on foundation phase student teachers as they experience significant challenges to their self-efficacy beliefs in mathematics and mathematics teaching. Self-efficacy is the key theory of the study. It stems from Bandura’s social cognitive theory and is an individual’s judgments about their capabilities, skills and perceived performance. This qualitative research adopts an interpretivist approach which seeks to identify Bed foundation phase fourth year student teachers’ self-efficacy beliefs towards teaching mathematics and the self-reported factors influencing such beliefs. This research found that BEd foundation phase fourth year student teachers have low self-efficacy beliefs towards teaching mathematics. The purpose of this research is to raise awareness of the BEd student teachers’ low self-efficacy beliefs towards teaching mathematics. The results from this research will provide a platform for future intervention research, as well as potentially influencing student teacher training programmes.
- Full Text:
- Date Issued: 2020
Impacts of cattle grazing pressure on vegetation and soil characteristics in an arid grassland of South Africa
- Authors: Botha, Gert Stephanus
- Date: 2020
- Subjects: Grazing -- Environmental aspects -- South Africa , Cattle -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/${Handle} , vital:39749
- Description: Natural rangelands are often degraded due to the implementation of incorrect grazing systems. One potential solution is the use of short duration, high intensity grazing. The impacts of this grazing system on, inter alia, vegetation and soil properties have not yet been comprehensively tested within the arid rangelands of South Africa. This study aimed to determine the impacts of grazing intensity on vegetation composition, forage quantity and quality, and soil compaction, soil water infiltration rates and soil chemical properties in an arid grassland in South Africa. The following three grazing treatments were compared: no grazing (NG), low intensity grazing (LIG) and high intensity grazing (HIG). A total of 18 plots (six replicates per treatment) were grazed with Bonsmara cattle. Each plot, 4 ha in size, was surveyed pre-grazing, directly after grazing, and again three, six and 12 months post-grazing. The results indicated that different grazing intensities did not affect grass diversity and the veld condition a year after grazing. Phytomass was influenced by grazing intensity, with no grazing having the highest phytomass throughout the study period. Soil compaction differed among seasons but not among treatments, with summer surveys recording the lowest soil compaction rates. The soil water infiltration rates did not differ between the three different treatments, indicating that grazing intensity did not affect infiltration rates. However, grazing did seem to improve soil nutrient levels when compared to NG. The grazed treatments had higher NH4+, K+, and organic carbon than the NG treatment. Nevertheless, there was no significant difference in nutrients levels when comparing the LIG system to the HIG system. When comparing the soil nutrients levels within a treatment over time, only the HIG treatment showed an increase in soil nutrient levels (Mg2+) over time, whereas the LIG and NG treatments showed no changed throughout the study period. Generally, the study results indicated that in the short term there was no advantage to using higher grazing intensity, although the presence of grazing (as opposed to no grazing) is advantageous to arid grassland functioning.
- Full Text:
- Date Issued: 2020
- Authors: Botha, Gert Stephanus
- Date: 2020
- Subjects: Grazing -- Environmental aspects -- South Africa , Cattle -- Feeding and feeds -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/${Handle} , vital:39749
- Description: Natural rangelands are often degraded due to the implementation of incorrect grazing systems. One potential solution is the use of short duration, high intensity grazing. The impacts of this grazing system on, inter alia, vegetation and soil properties have not yet been comprehensively tested within the arid rangelands of South Africa. This study aimed to determine the impacts of grazing intensity on vegetation composition, forage quantity and quality, and soil compaction, soil water infiltration rates and soil chemical properties in an arid grassland in South Africa. The following three grazing treatments were compared: no grazing (NG), low intensity grazing (LIG) and high intensity grazing (HIG). A total of 18 plots (six replicates per treatment) were grazed with Bonsmara cattle. Each plot, 4 ha in size, was surveyed pre-grazing, directly after grazing, and again three, six and 12 months post-grazing. The results indicated that different grazing intensities did not affect grass diversity and the veld condition a year after grazing. Phytomass was influenced by grazing intensity, with no grazing having the highest phytomass throughout the study period. Soil compaction differed among seasons but not among treatments, with summer surveys recording the lowest soil compaction rates. The soil water infiltration rates did not differ between the three different treatments, indicating that grazing intensity did not affect infiltration rates. However, grazing did seem to improve soil nutrient levels when compared to NG. The grazed treatments had higher NH4+, K+, and organic carbon than the NG treatment. Nevertheless, there was no significant difference in nutrients levels when comparing the LIG system to the HIG system. When comparing the soil nutrients levels within a treatment over time, only the HIG treatment showed an increase in soil nutrient levels (Mg2+) over time, whereas the LIG and NG treatments showed no changed throughout the study period. Generally, the study results indicated that in the short term there was no advantage to using higher grazing intensity, although the presence of grazing (as opposed to no grazing) is advantageous to arid grassland functioning.
- Full Text:
- Date Issued: 2020
Optical diamond turning of rapidly solidified aluminium alloy grade - 431
- Authors: Oyekunle, Funsho Adekunle
- Date: 2020
- Subjects: Aluminum alloys
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46860 , vital:39670
- Description: The high demand for ultraprecision machining systems is increasing day by day. The technology leads to increased productivity and quality manufactured products, with an excellent surface finish. Therefore, these products are in demand in many industrial fields such as space, national defence, the medical industry and other high-tech industries. Single point diamond turning (SPDT) is the core technology of ultraprecision machining, which makes use of single-point crystalline diamond as a cutting tool. This technique is used for machining an extensive selection of complex optical surfaces and other engineering products with a quality surface finish. SPDT can achieve dimensional tolerances in order of 0.01um and surface roughness in order of 1nm. SPDT is not restricted, but mostly applicable, to non-ferrous alloys; due to their reflective properties and microstructure that discourages tool wear. The focus of this study is the development of predictive optimisation models, used to analyse the influence of machining parameters (speed, feed, and depth of cut) on surface roughness. Moreover, the study aims to obtain the optimal machining parameters that would lead to minimum surface roughness during the diamond turning of Rapidly Solidified Aluminium (RSA) 431. In this study, Precitech Nanoform 250 Ultra grind machine was used to perform two experiments on RSA 431. The first machining process, experiment 1, was carried out using pressurized kerosene mist; while experiment 2 was carried out with water as the cutting fluid. In each experiment, machine parameters were varied at intervals and the surface roughness of the workpiece was measured at each variation. The measurements were taken through a contact method using Taylor Hobson PGI Dimension XL surface Profilometer. Acoustic emission (AE) was employed as a precision sensing technique – to optimize the machining quality process and provide indications of the expected surface roughness. The results obtained revealed that better surface roughness can be generated when RSA 431 is diamond-turned using water as a cutting fluid, rather than kerosene mist. Predictive models for surface roughness were developed for each experiment, using response surface methodology (RSM) and artificial neural networks (ANN). Moreover, RSM was used for optimisation. Time domain features acquired from AE signals, together with the three cutting parameters, were used as input parameters in the ANN design. The results of the predictive models show a close relationship between the predicted values and the experimental values for surface roughness. The developed models have been compared in terms of accuracy and cost of computation - using the mean absolute percentage error (MAPE).
- Full Text:
- Date Issued: 2020
- Authors: Oyekunle, Funsho Adekunle
- Date: 2020
- Subjects: Aluminum alloys
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46860 , vital:39670
- Description: The high demand for ultraprecision machining systems is increasing day by day. The technology leads to increased productivity and quality manufactured products, with an excellent surface finish. Therefore, these products are in demand in many industrial fields such as space, national defence, the medical industry and other high-tech industries. Single point diamond turning (SPDT) is the core technology of ultraprecision machining, which makes use of single-point crystalline diamond as a cutting tool. This technique is used for machining an extensive selection of complex optical surfaces and other engineering products with a quality surface finish. SPDT can achieve dimensional tolerances in order of 0.01um and surface roughness in order of 1nm. SPDT is not restricted, but mostly applicable, to non-ferrous alloys; due to their reflective properties and microstructure that discourages tool wear. The focus of this study is the development of predictive optimisation models, used to analyse the influence of machining parameters (speed, feed, and depth of cut) on surface roughness. Moreover, the study aims to obtain the optimal machining parameters that would lead to minimum surface roughness during the diamond turning of Rapidly Solidified Aluminium (RSA) 431. In this study, Precitech Nanoform 250 Ultra grind machine was used to perform two experiments on RSA 431. The first machining process, experiment 1, was carried out using pressurized kerosene mist; while experiment 2 was carried out with water as the cutting fluid. In each experiment, machine parameters were varied at intervals and the surface roughness of the workpiece was measured at each variation. The measurements were taken through a contact method using Taylor Hobson PGI Dimension XL surface Profilometer. Acoustic emission (AE) was employed as a precision sensing technique – to optimize the machining quality process and provide indications of the expected surface roughness. The results obtained revealed that better surface roughness can be generated when RSA 431 is diamond-turned using water as a cutting fluid, rather than kerosene mist. Predictive models for surface roughness were developed for each experiment, using response surface methodology (RSM) and artificial neural networks (ANN). Moreover, RSM was used for optimisation. Time domain features acquired from AE signals, together with the three cutting parameters, were used as input parameters in the ANN design. The results of the predictive models show a close relationship between the predicted values and the experimental values for surface roughness. The developed models have been compared in terms of accuracy and cost of computation - using the mean absolute percentage error (MAPE).
- Full Text:
- Date Issued: 2020