Health and fitness of young, healthy adult females and the effect of an eight week pilates intervention
- Authors: Eaton, Lara Lee
- Date: 2018
- Subjects: Physical fitness for women -- South Africa -- Makhanda , Pilates method , Exercise for women -- South Africa -- Makhanda , Exercise -- Health aspects -- South Africa -- Makhanda , Exercise -- Physiological aspects -- South Africa -- Makhanda
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58267 , vital:27112
- Description: Purpose: The first phase of this study aimed to investigate the health and fitness status of young adult females in the local community. The second phase of this study investigated the impact of an eight week progressive Pilates intervention on selected health and fitness parameters in this cohort. Methods: Healthy young adult females aged 18-26 years (n=96), from the local community, partook in once-off tests including anthropometric measures (stature, body mass, Body Mass Index and waist circumference) as well as fitness parameters including balance, flexibility, muscular strength and endurance, and lastly lumbo-pelvic stability. Health measures investigated included blood pressure and spirometry. Where possible, results were compared to those of similar populations from national surveys or published normative data. Sedentary volunteers from this cohort were then randomised into a Pilates Exercise (PEx, n=12) or an inactive Control (Con, n=11) group, with their results from Phase 1 serving as baseline measures. Pilates classes were held twice weekly (60 minutes per session). All the measures from phase 1 were repeated at weeks 4 and 8. An additional intervention test included Transversus abdominis recruitment. Participants maintained habitual dietary intake and energy expenditure throughout. Nine PEx group and eight Con group participants completed the intervention. Results: The current sample (phase 1) was found to be healthier than comparative populations from national surveys, and significant differences (p<0.05) were found for all comparisons except Forced Expiratory Volume (FEV1), (p=0.64). Physical activity levels (230 min.week-1) exceeded that of the recommend weekly threshold (150 min.week-1). BMI, waist circumference, blood pressure and spirometry measures were all found to be within suggested healthy normal ranges. Pilates significantly improved lumbo-pelvic stability in the PEx group at weeks 4 (p<0.005) and 8 (p<0.002). Similarly, abdominal (p=0.00, d=1.1), upper limb (p=0.037, d=0.9) and lower limb endurance (p=0.02, d=1.0, between group d=0.73 for PEx) also improved with no changes in the Con group. PEx energy expenditure significantly increased from baseline to weeks 4 (p=0.007, d=10.7) and 8 (p=0.027, d=0.64), however body mass was maintained throughout. Conversely, Minute Ventilation decreased in the PEx cohort (p=0.010, d=0.95) from weeks 4 to 8. The Con group showed significant increases in body mass (p=0.018), leg strength (within-group Cohen’s d=-1.08 between weeks 0-8; d=-2 between weeks 4-8) and dynamic balance (p=0.01, d=-0.5). While no within-group changes were observed, Protein intake was significantly greater (p=0.036, d>0.8 at baseline and week 8) in the PEx group throughout the intervention. Medium between-group effect sizes (d>0.5) were noted for PEx BMI and waist circumference measures at all time points. Further, although not significant, the large within-group effect size (d=-0.84) between baseline and week 8 for PEx systolic blood pressure, suggested the 9 mm Hg was meaningful. The same time period also indicated a large within-group effect size (d=-0.8) for PEx dynamic balance, and a medium Cohen’s d for (d=0.57) PEx static balance. Conclusion: The local population of young adult females was found to be significantly healthier than those of comparable national samples. Further, Pilates participation significantly improved lumbo-pelvic stability and muscular endurance with meaningful changes in systolic blood pressure, and balance in previously sedentary young, adult females. Body mass was also maintained.
- Full Text:
- Date Issued: 2018
- Authors: Eaton, Lara Lee
- Date: 2018
- Subjects: Physical fitness for women -- South Africa -- Makhanda , Pilates method , Exercise for women -- South Africa -- Makhanda , Exercise -- Health aspects -- South Africa -- Makhanda , Exercise -- Physiological aspects -- South Africa -- Makhanda
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58267 , vital:27112
- Description: Purpose: The first phase of this study aimed to investigate the health and fitness status of young adult females in the local community. The second phase of this study investigated the impact of an eight week progressive Pilates intervention on selected health and fitness parameters in this cohort. Methods: Healthy young adult females aged 18-26 years (n=96), from the local community, partook in once-off tests including anthropometric measures (stature, body mass, Body Mass Index and waist circumference) as well as fitness parameters including balance, flexibility, muscular strength and endurance, and lastly lumbo-pelvic stability. Health measures investigated included blood pressure and spirometry. Where possible, results were compared to those of similar populations from national surveys or published normative data. Sedentary volunteers from this cohort were then randomised into a Pilates Exercise (PEx, n=12) or an inactive Control (Con, n=11) group, with their results from Phase 1 serving as baseline measures. Pilates classes were held twice weekly (60 minutes per session). All the measures from phase 1 were repeated at weeks 4 and 8. An additional intervention test included Transversus abdominis recruitment. Participants maintained habitual dietary intake and energy expenditure throughout. Nine PEx group and eight Con group participants completed the intervention. Results: The current sample (phase 1) was found to be healthier than comparative populations from national surveys, and significant differences (p<0.05) were found for all comparisons except Forced Expiratory Volume (FEV1), (p=0.64). Physical activity levels (230 min.week-1) exceeded that of the recommend weekly threshold (150 min.week-1). BMI, waist circumference, blood pressure and spirometry measures were all found to be within suggested healthy normal ranges. Pilates significantly improved lumbo-pelvic stability in the PEx group at weeks 4 (p<0.005) and 8 (p<0.002). Similarly, abdominal (p=0.00, d=1.1), upper limb (p=0.037, d=0.9) and lower limb endurance (p=0.02, d=1.0, between group d=0.73 for PEx) also improved with no changes in the Con group. PEx energy expenditure significantly increased from baseline to weeks 4 (p=0.007, d=10.7) and 8 (p=0.027, d=0.64), however body mass was maintained throughout. Conversely, Minute Ventilation decreased in the PEx cohort (p=0.010, d=0.95) from weeks 4 to 8. The Con group showed significant increases in body mass (p=0.018), leg strength (within-group Cohen’s d=-1.08 between weeks 0-8; d=-2 between weeks 4-8) and dynamic balance (p=0.01, d=-0.5). While no within-group changes were observed, Protein intake was significantly greater (p=0.036, d>0.8 at baseline and week 8) in the PEx group throughout the intervention. Medium between-group effect sizes (d>0.5) were noted for PEx BMI and waist circumference measures at all time points. Further, although not significant, the large within-group effect size (d=-0.84) between baseline and week 8 for PEx systolic blood pressure, suggested the 9 mm Hg was meaningful. The same time period also indicated a large within-group effect size (d=-0.8) for PEx dynamic balance, and a medium Cohen’s d for (d=0.57) PEx static balance. Conclusion: The local population of young adult females was found to be significantly healthier than those of comparable national samples. Further, Pilates participation significantly improved lumbo-pelvic stability and muscular endurance with meaningful changes in systolic blood pressure, and balance in previously sedentary young, adult females. Body mass was also maintained.
- Full Text:
- Date Issued: 2018
Historical analysis of leadership styles of headmasters at Kingswood College from 1993 to 2017
- Authors: Howden, Ryan Bradley
- Date: 2018
- Subjects: Educational leadership -- South Africa -- Makhanda -- Case studies , Kingswood College -- History , Educational change -- South Africa -- Makhanda , School principals-- South Africa -- Makhanda , Transformational leadership -- South Africa -- Makhanda , Private schools -- Business management , Full Range Leadership
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/62133 , vital:28131
- Description: A significant interest in school educational leadership has developed over the past two decades, whereby effective leadership is required in a continually changing educational environment. This study is a historical analysis of leadership styles of headmasters at Kingswood College in Grahamstown (Eastern Cape, South Africa) from 1993 to 2017. The aim is to identify leadership style(s) of headmasters using the Full Range Leadership (FRL) model as a guiding framework; to describe and interpret these style(s) in relation to the headmaster’s tenure; and to compare the headmasters’ leadership styles, noting key similarities and differences. The research method consists of interviews and a historical archival analysis. The researcher’s expectation is that headmasters will elicit a transformational leadership approach. Key findings were somewhat consistent with this hypothesis, as headmasters exhibit a general trend towards transformational leadership; although each headmaster identifies with a unique facet of transformational leadership, together with relevant supporting leadership style(s) that emerged from the data. Upon comparing headmasters, their primary leadership styles were as follows: Wilkinson identified with transactional, transformational and servant leadership; Hawke showed evidence of a transformational servant leader; Arguile elicited transformational and principle-based leadership; and Trafford depicted transformational and participative leadership. The researcher found that multiple factors in an ever-changing educational environment promoted the need for transformational leadership. The relationship between business management and educational leadership emerges as a key reflection, thus further research is required in this regard.
- Full Text:
- Date Issued: 2018
- Authors: Howden, Ryan Bradley
- Date: 2018
- Subjects: Educational leadership -- South Africa -- Makhanda -- Case studies , Kingswood College -- History , Educational change -- South Africa -- Makhanda , School principals-- South Africa -- Makhanda , Transformational leadership -- South Africa -- Makhanda , Private schools -- Business management , Full Range Leadership
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/62133 , vital:28131
- Description: A significant interest in school educational leadership has developed over the past two decades, whereby effective leadership is required in a continually changing educational environment. This study is a historical analysis of leadership styles of headmasters at Kingswood College in Grahamstown (Eastern Cape, South Africa) from 1993 to 2017. The aim is to identify leadership style(s) of headmasters using the Full Range Leadership (FRL) model as a guiding framework; to describe and interpret these style(s) in relation to the headmaster’s tenure; and to compare the headmasters’ leadership styles, noting key similarities and differences. The research method consists of interviews and a historical archival analysis. The researcher’s expectation is that headmasters will elicit a transformational leadership approach. Key findings were somewhat consistent with this hypothesis, as headmasters exhibit a general trend towards transformational leadership; although each headmaster identifies with a unique facet of transformational leadership, together with relevant supporting leadership style(s) that emerged from the data. Upon comparing headmasters, their primary leadership styles were as follows: Wilkinson identified with transactional, transformational and servant leadership; Hawke showed evidence of a transformational servant leader; Arguile elicited transformational and principle-based leadership; and Trafford depicted transformational and participative leadership. The researcher found that multiple factors in an ever-changing educational environment promoted the need for transformational leadership. The relationship between business management and educational leadership emerges as a key reflection, thus further research is required in this regard.
- Full Text:
- Date Issued: 2018
How the roles of CEO's differ in response to different circumstances and in the context of succession: Anglo American-a case study
- Authors: Ball, Leslie
- Date: 2018
- Subjects: Organizational change , Strategic planning , Executive succession , Anglo American Corporation of South Africa, ltd.
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/60799 , vital:27832
- Description: A review of the literature revealed that firms are inherently influenced by leadership in the upper echelons of the organization. The seminal paper of Hambrick and Mason (1984) has sparked much interest in the realm of organizational leadership. Studies involving organizational leadership have concentrated on leadership styles, the manner in which leadership takes place, leadership succession and organizational performance in an attempt to understand the dynamics of the senior leadership of organizations. Research has also explored how changes in the top management of firms has impacted its performance. This research has primarily been concerned with how a firm is impacted, once succession takes place, and has focused on financial performance, change in strategy and stockholder reaction (Shen & Cannella, 2002; Barron, Chulkov & Waddell, 2011; Friedman & Singh, 1989). Although their predisposition will largely influence the manner in which the incoming CEO acts, the literature has largely neglected the role the incoming CEO must fulfil, and how he/she steers the company, once appointed. In response, the following aim was developed to address this gap: To describe how the roles of two CEO's of the same company differed, during different time periods. The CEO assumes various strategic leadership roles, which they carry out in the context of their new environment once succession has taken place. From the literature, six strategic leadership roles were identified, which formed the foundation of this study. These were strategy formulation, strategy implementation, developing organizational culture, emphasizing ethical practices, managing the firm's resource portfolio and establishing balanced controls. The study set out to comparatively analyze two CEO's of the same firm during different periods. Both CEO's were investigated from the perspective of strategic leadership roles, allowing a comparison of their behaviour. The study analyses and describes these roles, and how they differed between the CEO's, in reaction to differing situational factors and in the context of succession. The study employed a deductive qualitative case study research design. This allowed the researcher to examine the complex phenomenon which have previously been studied at a more superficial level using quantitative methods (Baxter & Jack, 2008; Parrino, 1997; Jooste & Fourie, 2009). A qualitative methodological approach allowed the researcher to examine the topic through a lens which takes into account human variables and processes (Baxter & Jack, 2008). Data was sampled using purposive and convenience sampling while applying the critical incident technique. Data was collected through information sources such as news articles, press releases, annual reports, online interviews, news websites and other documents. Thematical analysis was used during the analysis phase of the study and allowed for patterns and links to be drawn between the collected data. The succession from one CEO to the next served as the comparative element of the study, which allowed for a contrasting of how both CEO's carried out their strategic leadership roles by adapting to their environment, and how they guided the strategic trajectory of the company. The study also took into account what both CEO's were confronted with at the start of their tenure and how this influenced how they carried out their leadership roles. It was found that Cynthia Carroll exercised her roles in a manner which addressed ethical and stakeholder engagement issues within the business. This was translated directly into how she guided the trajectory of the company. Upon appointment, Mark Cutifani exercised his roles in a manner which addressed the organizational performance and financial well-being of the company. This translated directly into how he shaped Anglo's trajectory in an attempt to better its financial performance. Given how they exercised their strategic roles in the company, each CEO influenced Anglo American's direction in a different way, which in turn, influenced the performance of the organization. It was shown that Cynthia Carroll improved the stakeholder engagement, communication and safety within the company, demonstrating behaviour that emphasized the importance of the ethics of the company. When the business had been carrying out its ethical practices effectively, but underperforming financially, Cutifani demonstrated the roles which would be geared toward resurrecting the organizational performance of the organization. Recommendations are made for further research including applying the same research method to investigate how these roles are carried out in companies which operate in a broad spectrum of industries.
- Full Text:
- Date Issued: 2018
- Authors: Ball, Leslie
- Date: 2018
- Subjects: Organizational change , Strategic planning , Executive succession , Anglo American Corporation of South Africa, ltd.
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/60799 , vital:27832
- Description: A review of the literature revealed that firms are inherently influenced by leadership in the upper echelons of the organization. The seminal paper of Hambrick and Mason (1984) has sparked much interest in the realm of organizational leadership. Studies involving organizational leadership have concentrated on leadership styles, the manner in which leadership takes place, leadership succession and organizational performance in an attempt to understand the dynamics of the senior leadership of organizations. Research has also explored how changes in the top management of firms has impacted its performance. This research has primarily been concerned with how a firm is impacted, once succession takes place, and has focused on financial performance, change in strategy and stockholder reaction (Shen & Cannella, 2002; Barron, Chulkov & Waddell, 2011; Friedman & Singh, 1989). Although their predisposition will largely influence the manner in which the incoming CEO acts, the literature has largely neglected the role the incoming CEO must fulfil, and how he/she steers the company, once appointed. In response, the following aim was developed to address this gap: To describe how the roles of two CEO's of the same company differed, during different time periods. The CEO assumes various strategic leadership roles, which they carry out in the context of their new environment once succession has taken place. From the literature, six strategic leadership roles were identified, which formed the foundation of this study. These were strategy formulation, strategy implementation, developing organizational culture, emphasizing ethical practices, managing the firm's resource portfolio and establishing balanced controls. The study set out to comparatively analyze two CEO's of the same firm during different periods. Both CEO's were investigated from the perspective of strategic leadership roles, allowing a comparison of their behaviour. The study analyses and describes these roles, and how they differed between the CEO's, in reaction to differing situational factors and in the context of succession. The study employed a deductive qualitative case study research design. This allowed the researcher to examine the complex phenomenon which have previously been studied at a more superficial level using quantitative methods (Baxter & Jack, 2008; Parrino, 1997; Jooste & Fourie, 2009). A qualitative methodological approach allowed the researcher to examine the topic through a lens which takes into account human variables and processes (Baxter & Jack, 2008). Data was sampled using purposive and convenience sampling while applying the critical incident technique. Data was collected through information sources such as news articles, press releases, annual reports, online interviews, news websites and other documents. Thematical analysis was used during the analysis phase of the study and allowed for patterns and links to be drawn between the collected data. The succession from one CEO to the next served as the comparative element of the study, which allowed for a contrasting of how both CEO's carried out their strategic leadership roles by adapting to their environment, and how they guided the strategic trajectory of the company. The study also took into account what both CEO's were confronted with at the start of their tenure and how this influenced how they carried out their leadership roles. It was found that Cynthia Carroll exercised her roles in a manner which addressed ethical and stakeholder engagement issues within the business. This was translated directly into how she guided the trajectory of the company. Upon appointment, Mark Cutifani exercised his roles in a manner which addressed the organizational performance and financial well-being of the company. This translated directly into how he shaped Anglo's trajectory in an attempt to better its financial performance. Given how they exercised their strategic roles in the company, each CEO influenced Anglo American's direction in a different way, which in turn, influenced the performance of the organization. It was shown that Cynthia Carroll improved the stakeholder engagement, communication and safety within the company, demonstrating behaviour that emphasized the importance of the ethics of the company. When the business had been carrying out its ethical practices effectively, but underperforming financially, Cutifani demonstrated the roles which would be geared toward resurrecting the organizational performance of the organization. Recommendations are made for further research including applying the same research method to investigate how these roles are carried out in companies which operate in a broad spectrum of industries.
- Full Text:
- Date Issued: 2018
Human capital and other stories
- Authors: Dludlu, John
- Date: 2018
- Subjects: Short stories, South African (English) -- 21st century , South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63121 , vital:28365
- Description: My collection of short stories is set mostly in Gauteng and revolves around mainly the lives of the urban, black elite almost three decades after the first non‐racial elections in South Africa. It captures emerging trends and fault lines and enquires into whether South Africa can continue on a different path from that of the rest of the continent. Themes covered in the collection, which still espouses idealism, include the acquisition of power, status and money, the use and abuse of these, as well as the psychosocial effects of money on this group. My writing is inspired by the courageous, inventive and introspective writings of the Drum generation of writers William Bloke Modisane, Nat Nakasa and Can Themba, as well as the use of language and the experimental form of writing as embodied in the work of Lidia Yuknavitch to deal with similarly pressing social issues of the day.
- Full Text:
- Date Issued: 2018
- Authors: Dludlu, John
- Date: 2018
- Subjects: Short stories, South African (English) -- 21st century , South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63121 , vital:28365
- Description: My collection of short stories is set mostly in Gauteng and revolves around mainly the lives of the urban, black elite almost three decades after the first non‐racial elections in South Africa. It captures emerging trends and fault lines and enquires into whether South Africa can continue on a different path from that of the rest of the continent. Themes covered in the collection, which still espouses idealism, include the acquisition of power, status and money, the use and abuse of these, as well as the psychosocial effects of money on this group. My writing is inspired by the courageous, inventive and introspective writings of the Drum generation of writers William Bloke Modisane, Nat Nakasa and Can Themba, as well as the use of language and the experimental form of writing as embodied in the work of Lidia Yuknavitch to deal with similarly pressing social issues of the day.
- Full Text:
- Date Issued: 2018
I won’t be long
- Mhlambi, Ntombi Kayise Millicent
- Authors: Mhlambi, Ntombi Kayise Millicent
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , South African poetry (English) -- 21st century , Short stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63603 , vital:28446
- Description: My thesis is a weave of short stories, flash fiction and vignettes of prose-poetry. It uses lyrical, scenic and explorative modes to explore the stories of women, past, present and future, from all walks of life. These women, young and old, struggle to find their way within a ‘world’ characterised as Salithambo (the pink castle) whose structures and survival preys on their bodies. The stories explore the themes of girlhood and maturation, violence (specifically against women), animality, scatology, time, gender roles and expectations, and their rejection. I draw inspiration, stylistically, from Irenosen Okojie’s depiction of beauty and terror in the same sentence; Selah Saterstrom’s fragmented plot and directorial stroke; Taban Lo Liyong & Amos Tutuola’s avant-gardism and amplification of language; Adania Shibli’s sensorial and spare prose, Lyudmila Petrushevskaya, Lily Hoang & Carol Oates’ normalized magic spell, Athena Villaverde & Espido Freire’s imaginative overload of childhood; Shelley Jackson & Chevisa Woods’ construction of body parts as bearing texts or as texts themselves.
- Full Text:
- Date Issued: 2018
- Authors: Mhlambi, Ntombi Kayise Millicent
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , South African poetry (English) -- 21st century , Short stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63603 , vital:28446
- Description: My thesis is a weave of short stories, flash fiction and vignettes of prose-poetry. It uses lyrical, scenic and explorative modes to explore the stories of women, past, present and future, from all walks of life. These women, young and old, struggle to find their way within a ‘world’ characterised as Salithambo (the pink castle) whose structures and survival preys on their bodies. The stories explore the themes of girlhood and maturation, violence (specifically against women), animality, scatology, time, gender roles and expectations, and their rejection. I draw inspiration, stylistically, from Irenosen Okojie’s depiction of beauty and terror in the same sentence; Selah Saterstrom’s fragmented plot and directorial stroke; Taban Lo Liyong & Amos Tutuola’s avant-gardism and amplification of language; Adania Shibli’s sensorial and spare prose, Lyudmila Petrushevskaya, Lily Hoang & Carol Oates’ normalized magic spell, Athena Villaverde & Espido Freire’s imaginative overload of childhood; Shelley Jackson & Chevisa Woods’ construction of body parts as bearing texts or as texts themselves.
- Full Text:
- Date Issued: 2018
In silico characterization of plasmodial transketolases as potential malaria drug target
- Authors: Boateng, Rita Afriyie
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63540 , vital:28433
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
- Authors: Boateng, Rita Afriyie
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63540 , vital:28433
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
In silico study of Plasmodium 1-deoxy-dxylulose 5-phosphate reductoisomerase (DXR) for identification of novel inhibitors from SANCDB
- Authors: Diallo, Bakary N'tji
- Date: 2018
- Subjects: Plasmodium 1-deoxy-dxylulose 5-phosphate reductoisomerase , Isoprenoids , Plasmodium , Antimalarials , Malaria -- Chemotherapy , Molecules -- Models , Molecular dynamics , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64012 , vital:28523
- Description: Malaria remains a major health concern with a complex parasite constantly developing resistance to the different drugs introduced to treat it, threatening the efficacy of the current ACT treatment recommended by WHO (World Health Organization). Different antimalarial compounds with different mechanisms of action are ideal as this decreases chances of resistance occurring. Inhibiting DXR and consequently the MEP pathway is a good strategy to find a new antimalarial with a novel mode of action. From literature, all the enzymes of the MEP pathway have also been shown to be indispensable for the synthesis of isoprenoids. They have been validated as drug targets and the X-ray structure of each of the enzymes has been solved. DXR is a protein which catalyses the second step of the MEP pathway. There are currently 255 DXR inhibitors in the Binding Database (accessed November 2017) generally based on the fosmidomycin structural scaffold and thus often showing poor drug likeness properties. This study aims to research new DXR inhibitors using in silico techniques. We analysed the protein sequence and built 3D models in close and open conformations for the different Plasmodium sequences. Then SANCDB compounds were screened to identify new potential DXR inhibitors with new chemical scaffolds. Finally, the identified hits were submitted to molecular dynamics studies, preceded by a parameterization of the manganese atom in the protein active site.
- Full Text:
- Date Issued: 2018
- Authors: Diallo, Bakary N'tji
- Date: 2018
- Subjects: Plasmodium 1-deoxy-dxylulose 5-phosphate reductoisomerase , Isoprenoids , Plasmodium , Antimalarials , Malaria -- Chemotherapy , Molecules -- Models , Molecular dynamics , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64012 , vital:28523
- Description: Malaria remains a major health concern with a complex parasite constantly developing resistance to the different drugs introduced to treat it, threatening the efficacy of the current ACT treatment recommended by WHO (World Health Organization). Different antimalarial compounds with different mechanisms of action are ideal as this decreases chances of resistance occurring. Inhibiting DXR and consequently the MEP pathway is a good strategy to find a new antimalarial with a novel mode of action. From literature, all the enzymes of the MEP pathway have also been shown to be indispensable for the synthesis of isoprenoids. They have been validated as drug targets and the X-ray structure of each of the enzymes has been solved. DXR is a protein which catalyses the second step of the MEP pathway. There are currently 255 DXR inhibitors in the Binding Database (accessed November 2017) generally based on the fosmidomycin structural scaffold and thus often showing poor drug likeness properties. This study aims to research new DXR inhibitors using in silico techniques. We analysed the protein sequence and built 3D models in close and open conformations for the different Plasmodium sequences. Then SANCDB compounds were screened to identify new potential DXR inhibitors with new chemical scaffolds. Finally, the identified hits were submitted to molecular dynamics studies, preceded by a parameterization of the manganese atom in the protein active site.
- Full Text:
- Date Issued: 2018
Influence of knowledge of the end-point on pacing during a 2000m rowing time trial
- Authors: Ferreira, Dean
- Date: 2018
- Subjects: Rowing -- Training , Rowing -- Coaching , Endurance sports -- Training , Rowers -- Ability testing , Rowing -- Training -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61636 , vital:28044
- Description: Introduction: A typical 2000 m rowing race requires maximal force production over six to eight minutes. Optimal distribution of energetic resources during such a race is vital for optimal performance. There is little research examining the pacing strategies employed by rowers, particularly at the sub-elite level. Aim: The purpose of this investigation was to determine the influence of knowledge of the end-point on pacing during a 2000 m rowing time trial. Methods: Eleven male rowers from a university rowing club volunteered to partake in the study. Each participant completed three experimental trials on an indoor rowing ergometer, each 2000 m. The only difference between the trials was the nature of the information provided beforehand. At the start of the control trial, participants were correctly informed about the distance to be covered. Participants were not informed of the distance to be completed in the unknown trial. For the deceptive trial, participants were told 1000 m would be completed, but when this distance was reached, they were told to continue for another 1000 m. During each trial muscle activity, power output, heart rate, performance time and perceptions of effort were measured.Results: The control trial was significantly (p<0.05) faster than both the unknown and deceptive trials, however the deceptive trial was the fastest of all trials at the 1000 m distance. The unknown trial was slowest at 1000 m and at 2000 m. Muscle activity, RPE, heart rate and power output were significantly (p<0.05) lower in the unknown trial compared to the control and deceptive trial. The control trial exhibited a reverse J-shape pacing profile. The deceptive trial revealed a significant (p<0.05) reduction in performance time, heart rate, power output and muscle activity after the 1000 m interval. The first 500 m interval had the fastest performance and highest power output in all trials. In all trials, RPE was highest at the end of the 2000 m, the greatest reading being obtained at the end of the control trial. During the first 1000 m of the deceptive trial, the dependant variables were similar to those in the control trial. Once the deception was revealed, there was a significant (p<0.05) reduction in the muscle activity, heart rate and power output. Conclusion: The results of this study indicate that accurate end-point information is crucial to the development of an optimal pacing strategy, and ultimately to successful performance. Rowers tend to adopt the reverse J-shape pacing profile most often due to the tactical and physiological benefits offered by this strategy. Unknown or inaccurate end-point information resulted in performance decrements due to the uncertainty associated with the exercise bout.
- Full Text:
- Date Issued: 2018
- Authors: Ferreira, Dean
- Date: 2018
- Subjects: Rowing -- Training , Rowing -- Coaching , Endurance sports -- Training , Rowers -- Ability testing , Rowing -- Training -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61636 , vital:28044
- Description: Introduction: A typical 2000 m rowing race requires maximal force production over six to eight minutes. Optimal distribution of energetic resources during such a race is vital for optimal performance. There is little research examining the pacing strategies employed by rowers, particularly at the sub-elite level. Aim: The purpose of this investigation was to determine the influence of knowledge of the end-point on pacing during a 2000 m rowing time trial. Methods: Eleven male rowers from a university rowing club volunteered to partake in the study. Each participant completed three experimental trials on an indoor rowing ergometer, each 2000 m. The only difference between the trials was the nature of the information provided beforehand. At the start of the control trial, participants were correctly informed about the distance to be covered. Participants were not informed of the distance to be completed in the unknown trial. For the deceptive trial, participants were told 1000 m would be completed, but when this distance was reached, they were told to continue for another 1000 m. During each trial muscle activity, power output, heart rate, performance time and perceptions of effort were measured.Results: The control trial was significantly (p<0.05) faster than both the unknown and deceptive trials, however the deceptive trial was the fastest of all trials at the 1000 m distance. The unknown trial was slowest at 1000 m and at 2000 m. Muscle activity, RPE, heart rate and power output were significantly (p<0.05) lower in the unknown trial compared to the control and deceptive trial. The control trial exhibited a reverse J-shape pacing profile. The deceptive trial revealed a significant (p<0.05) reduction in performance time, heart rate, power output and muscle activity after the 1000 m interval. The first 500 m interval had the fastest performance and highest power output in all trials. In all trials, RPE was highest at the end of the 2000 m, the greatest reading being obtained at the end of the control trial. During the first 1000 m of the deceptive trial, the dependant variables were similar to those in the control trial. Once the deception was revealed, there was a significant (p<0.05) reduction in the muscle activity, heart rate and power output. Conclusion: The results of this study indicate that accurate end-point information is crucial to the development of an optimal pacing strategy, and ultimately to successful performance. Rowers tend to adopt the reverse J-shape pacing profile most often due to the tactical and physiological benefits offered by this strategy. Unknown or inaccurate end-point information resulted in performance decrements due to the uncertainty associated with the exercise bout.
- Full Text:
- Date Issued: 2018
Integration of small-scale mohair farmers into the commercial agricultural economy in Lesotho: a new institutional economics approach
- Authors: Rantlo, Montoeli Ashby
- Date: 2018
- Subjects: Farms, Small Lesotho , Mohair Lesotho , Institutional economics , Transaction costs , Informal sector (Economics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62275 , vital:28149
- Description: Agriculture continues to be a strategic sector in the development of most low-income countries like Lesotho where small-scale farming is the dominant livelihood activity that provides income and employment to the people. Smallholder farmers' integration into the commercial agricultural markets is a crucial element for economic development and has become a part of development strategies for developing countries and the objectives of international development institutions. The integration of the smallholders into these markets is dependent upon a number of factors including formal and informal institutions. Factors like population growth and demographic changes, technological change and introduction of new commodities, development of infrastructure and market institutions, development of the nonfarm sector and broader economy, rising labour opportunity costs, and macroeconomic, trade and sectoral policies affecting prices and other driving forces determine market participation. In addition, development of input and output markets, institutions like property rights and land tenure, market regulations, cultural and social factors affecting consumption preferences, production and market opportunities and constraints, agro-climatic conditions, and production and market related risks are other factors that affect the commercialisation process. On the other hand, factors like smallholder resource endowments including land and other natural capital, labour, physical capital, and human capital among others are household specific and considered internal determinants of market participation. Nevertheless, the decision to participate in agricultural markets lies with the individual farming household. Under the New Institutional Economics (NIE), this decision is influenced by institutional factors such as risk and preferences, factors which affect household production and the level of costs associated with market transactions. These market transactions are commonly referred to as transaction costs. The study focused on investigating the institutions that limit the integration of small-scale mohair farmers into the commercial agricultural economy in Lesotho. The documentation and evaluation of the institutional structure of the mohair industry is performed whereby the institutional factors influencing participation of small-scale mohair farmers in formal, informal and illegal markets in Lesotho and factors contributing to transaction costs associated with the integration of small-scale farmers into the commercial mohair sector are investigated. Therefore, the investigation will help to address the institutional problems hindering the development of an effective marketing structure for the commercialisation of small-scale mohair producers in Lesotho. The results of the study show that the small-scale mohair farmers that use the formal markets are integrated into the commercial agricultural economy and these farmers' integration into the mainstream economy is influenced by access to government support in the form of shearing sheds, transport subsidies and advisory services. They also have access to market information, marketing infrastructure, knowledge of grades and standards and secure property rights. Other factors that helped their integration into the commercial economy is their contractual agreements with mohair buyers, path dependent based decision making as well as the collective approach to mohair farming. The small-scale mohair farmers using the informal markets do not receive the advantages received by the famers in the formal markets. These small-scale mohair farmers are not integrated into the commercial markets and their only option is the informal markets and their participation in these markets is enhanced by their marketing arrangements with the informal traders, culture influenced decisions, social capital and prompt payments. Despite integration into the commercial agricultural economy, small-scale farmers that use formal markets face the challenges of power imbalances, mistrust and conflicts which may affect this integration into the commercial markets if left unchecked. The study concludes that in the face of institutional challenges, the small-scale mohair farmers using the formal markets are integrated into the commercial agricultural economy and there is potential for improvement of their integration as well as the integration of the small-scale mohair farmers that use the informal markets if institutional challenges are addressed.
- Full Text:
- Date Issued: 2018
- Authors: Rantlo, Montoeli Ashby
- Date: 2018
- Subjects: Farms, Small Lesotho , Mohair Lesotho , Institutional economics , Transaction costs , Informal sector (Economics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62275 , vital:28149
- Description: Agriculture continues to be a strategic sector in the development of most low-income countries like Lesotho where small-scale farming is the dominant livelihood activity that provides income and employment to the people. Smallholder farmers' integration into the commercial agricultural markets is a crucial element for economic development and has become a part of development strategies for developing countries and the objectives of international development institutions. The integration of the smallholders into these markets is dependent upon a number of factors including formal and informal institutions. Factors like population growth and demographic changes, technological change and introduction of new commodities, development of infrastructure and market institutions, development of the nonfarm sector and broader economy, rising labour opportunity costs, and macroeconomic, trade and sectoral policies affecting prices and other driving forces determine market participation. In addition, development of input and output markets, institutions like property rights and land tenure, market regulations, cultural and social factors affecting consumption preferences, production and market opportunities and constraints, agro-climatic conditions, and production and market related risks are other factors that affect the commercialisation process. On the other hand, factors like smallholder resource endowments including land and other natural capital, labour, physical capital, and human capital among others are household specific and considered internal determinants of market participation. Nevertheless, the decision to participate in agricultural markets lies with the individual farming household. Under the New Institutional Economics (NIE), this decision is influenced by institutional factors such as risk and preferences, factors which affect household production and the level of costs associated with market transactions. These market transactions are commonly referred to as transaction costs. The study focused on investigating the institutions that limit the integration of small-scale mohair farmers into the commercial agricultural economy in Lesotho. The documentation and evaluation of the institutional structure of the mohair industry is performed whereby the institutional factors influencing participation of small-scale mohair farmers in formal, informal and illegal markets in Lesotho and factors contributing to transaction costs associated with the integration of small-scale farmers into the commercial mohair sector are investigated. Therefore, the investigation will help to address the institutional problems hindering the development of an effective marketing structure for the commercialisation of small-scale mohair producers in Lesotho. The results of the study show that the small-scale mohair farmers that use the formal markets are integrated into the commercial agricultural economy and these farmers' integration into the mainstream economy is influenced by access to government support in the form of shearing sheds, transport subsidies and advisory services. They also have access to market information, marketing infrastructure, knowledge of grades and standards and secure property rights. Other factors that helped their integration into the commercial economy is their contractual agreements with mohair buyers, path dependent based decision making as well as the collective approach to mohair farming. The small-scale mohair farmers using the informal markets do not receive the advantages received by the famers in the formal markets. These small-scale mohair farmers are not integrated into the commercial markets and their only option is the informal markets and their participation in these markets is enhanced by their marketing arrangements with the informal traders, culture influenced decisions, social capital and prompt payments. Despite integration into the commercial agricultural economy, small-scale farmers that use formal markets face the challenges of power imbalances, mistrust and conflicts which may affect this integration into the commercial markets if left unchecked. The study concludes that in the face of institutional challenges, the small-scale mohair farmers using the formal markets are integrated into the commercial agricultural economy and there is potential for improvement of their integration as well as the integration of the small-scale mohair farmers that use the informal markets if institutional challenges are addressed.
- Full Text:
- Date Issued: 2018
Interaction of catechol O-methyltransferase with gold and silver nanoparticles
- Authors: Usman, Aminu
- Date: 2018
- Subjects: Parkinson's disease , Methyltransferases , Catechol , Nanoparticles
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/61818 , vital:28063 , DOI https://doi.org/10.21504/10962/61818
- Description: Catechol O-methyltransferase (S-adenosyl-Z-methionine: catechol O-methyltransferase; COMT; EC 2.1.1.6) is a ubiquitous enzyme that catalyses the transfer of a methyl group from the cofactor, S-adenosyl-Z-methionine (SAM) to a hydroxyl group of endogenous and exogenous catechol-containing moieties. The physiological role of this enzyme is the methylation and thereby inactivation of the catechol-containing bio-active and bio-toxic compounds, including catechol-neurotransmitters, catechol-estrogens and catechol-containing drugs. Activity of this enzyme is implicated in the treatment of Parkinson’s disease and is associated with other diseases including breast cancer and an array neuropsychological disorders, such as schizophrenia. This thesis explores the use of gold and silver nanoparticles (NPs) (AuNPs and AgNPs) to inhibit the catalytic activity of mammalian COMT. Because of its accessibility and availability, we initially investigated bovine soluble COMT (BSCOMT) from liver tissue. Bioinformatic analyses and structural modeling revealed high (>90%) sequence similarity between BSCOMT and human soluble COMT (HSCOMT). BSCOMT was partially purified to 7.78 fold, 1.65% yield and had a specific activity of 0.052 U/mg. It had pH and temperature optima of 8.5 and 40oC, respectively. The Km, Vmax, Kcat and Kcat/Km towards esculetin methylation were respectively 1.475±0.130 pM, 0.0353±0.001 pmol/ml/min, 1.748 x 10-2±5.0x10-4 min-1 and 1.18x10-2 M-1. min-1. HSCOMT was expressed in Escherichia coli BL21(DE3) which showed optimal activity for esculetin methylation at pH and temperature of 7.0 and 30°C, respectively. It was purified to 5.62 fold, 22.6% yield with a specific activity of 3.85 U/mg. HSCOMT kinetic plots, upon incubation of the reaction mixture at 30°C for 5 min before addition of SAM was hyperbolic with Km, Vmax, Kcat and Kcat/Km values of 1.79 pM, 0.412 pmol/ml/min, 2.08 min-1 and 1.165 M-1. min-1, respectively. AuNPs and AgNPs showed a concentration dependent inhibition of HSCOMT activity upon increasing the 5 min incubation time to 1 h. Interestingly, HSCOMT kinetics, with 1 h incubation at 30°C, showed a sigmoidal curve, as well as increased activity. Incubation of the reaction mixture in the presence of 60 pM AuNPs and/or AgNPs for 1 hreversed the observed sigmoidal to a hyperbolic curve, with kinetic parameters comparable to those of 5 min incubation. SDS-PAGE analyses of HSCOMT after the kinetic experiments showed the enzyme incubated for 5 min as a monomer, while that which was incubated for 1 h migrated substantially as dimer. However, the HSCOMT incubated for 1 h in the presence of 60 pM AuNPs and/or AgNPs migrated as a monomer. This indicated that the extension of the incubation period allowed the dimerization of HSCOMT, which exhibited sigmoidal kinetics and higher activity. The presence of NPs impeded the HSCOMT dimerization which decreased the activity. Varying the concentration of SAM suggested that SAM had an allosteric modulatory effect on HSCOMT. Absorption spectroscopy indicated adsorption of HSCOMT on the gold and silver NP surfaces and the formation of NPs-HSCOMT corona. Fluorescence spectroscopy showed that the interaction of HSCOMT with both gold and silver NPs was governed by a static quenching mechanism, implying the formation of a non-fluorescent fluorophore-NP complex at the ground state. Further fluorometric analyses indicated that both gold and silver NPs had contact with Trp143; that the interactions were spontaneous and were driven by electrostatic interactions. Fourier transform infrared spectroscopic studies showed the adsorption of HSCOMT of the NPs surfaces to cause relaxation of the enzyme’s B-sheet structures. Molecular docking studies indicated involvement of largely hydrophilic amino acids, with the interacting distances of less than 3.5A. These findings signify the potential of nanotechnology in the control of COMT catalytic activity for the management of the COMT-related disorders. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2018
- Full Text:
- Date Issued: 2018
- Authors: Usman, Aminu
- Date: 2018
- Subjects: Parkinson's disease , Methyltransferases , Catechol , Nanoparticles
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/61818 , vital:28063 , DOI https://doi.org/10.21504/10962/61818
- Description: Catechol O-methyltransferase (S-adenosyl-Z-methionine: catechol O-methyltransferase; COMT; EC 2.1.1.6) is a ubiquitous enzyme that catalyses the transfer of a methyl group from the cofactor, S-adenosyl-Z-methionine (SAM) to a hydroxyl group of endogenous and exogenous catechol-containing moieties. The physiological role of this enzyme is the methylation and thereby inactivation of the catechol-containing bio-active and bio-toxic compounds, including catechol-neurotransmitters, catechol-estrogens and catechol-containing drugs. Activity of this enzyme is implicated in the treatment of Parkinson’s disease and is associated with other diseases including breast cancer and an array neuropsychological disorders, such as schizophrenia. This thesis explores the use of gold and silver nanoparticles (NPs) (AuNPs and AgNPs) to inhibit the catalytic activity of mammalian COMT. Because of its accessibility and availability, we initially investigated bovine soluble COMT (BSCOMT) from liver tissue. Bioinformatic analyses and structural modeling revealed high (>90%) sequence similarity between BSCOMT and human soluble COMT (HSCOMT). BSCOMT was partially purified to 7.78 fold, 1.65% yield and had a specific activity of 0.052 U/mg. It had pH and temperature optima of 8.5 and 40oC, respectively. The Km, Vmax, Kcat and Kcat/Km towards esculetin methylation were respectively 1.475±0.130 pM, 0.0353±0.001 pmol/ml/min, 1.748 x 10-2±5.0x10-4 min-1 and 1.18x10-2 M-1. min-1. HSCOMT was expressed in Escherichia coli BL21(DE3) which showed optimal activity for esculetin methylation at pH and temperature of 7.0 and 30°C, respectively. It was purified to 5.62 fold, 22.6% yield with a specific activity of 3.85 U/mg. HSCOMT kinetic plots, upon incubation of the reaction mixture at 30°C for 5 min before addition of SAM was hyperbolic with Km, Vmax, Kcat and Kcat/Km values of 1.79 pM, 0.412 pmol/ml/min, 2.08 min-1 and 1.165 M-1. min-1, respectively. AuNPs and AgNPs showed a concentration dependent inhibition of HSCOMT activity upon increasing the 5 min incubation time to 1 h. Interestingly, HSCOMT kinetics, with 1 h incubation at 30°C, showed a sigmoidal curve, as well as increased activity. Incubation of the reaction mixture in the presence of 60 pM AuNPs and/or AgNPs for 1 hreversed the observed sigmoidal to a hyperbolic curve, with kinetic parameters comparable to those of 5 min incubation. SDS-PAGE analyses of HSCOMT after the kinetic experiments showed the enzyme incubated for 5 min as a monomer, while that which was incubated for 1 h migrated substantially as dimer. However, the HSCOMT incubated for 1 h in the presence of 60 pM AuNPs and/or AgNPs migrated as a monomer. This indicated that the extension of the incubation period allowed the dimerization of HSCOMT, which exhibited sigmoidal kinetics and higher activity. The presence of NPs impeded the HSCOMT dimerization which decreased the activity. Varying the concentration of SAM suggested that SAM had an allosteric modulatory effect on HSCOMT. Absorption spectroscopy indicated adsorption of HSCOMT on the gold and silver NP surfaces and the formation of NPs-HSCOMT corona. Fluorescence spectroscopy showed that the interaction of HSCOMT with both gold and silver NPs was governed by a static quenching mechanism, implying the formation of a non-fluorescent fluorophore-NP complex at the ground state. Further fluorometric analyses indicated that both gold and silver NPs had contact with Trp143; that the interactions were spontaneous and were driven by electrostatic interactions. Fourier transform infrared spectroscopic studies showed the adsorption of HSCOMT of the NPs surfaces to cause relaxation of the enzyme’s B-sheet structures. Molecular docking studies indicated involvement of largely hydrophilic amino acids, with the interacting distances of less than 3.5A. These findings signify the potential of nanotechnology in the control of COMT catalytic activity for the management of the COMT-related disorders. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2018
- Full Text:
- Date Issued: 2018
Interactions between three biological control agents of water hyacinth, Eichhornia crassipes (Mart.) Solms (Pontederiaceae) in South Africa
- Authors: Petela, Nomvume
- Date: 2018
- Subjects: Water hyacinth -- South Africa , Water hyacinth -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Curculionidae , Delphacidae , Miridae , Neochetina eichhorniae Warner , Megamelus scutellaris Berg , Eccritotarsus eichhorniae Henry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60676 , vital:27814
- Description: Water hyacinth, Eichhomia crassipes (Mart.) Solms (Pontederiaceae) is a free-floating perennial weed that is regarded as the worst aquatic weed in the world because of its negative impacts on aquatic ecosystems. It is native to the Amazon Basin of South America, but since the late 1800s has spread throughout the world. The first record of the weed in South Africa was noted in 1908 on the Cape Flats and in KwaZulu-Natal, but it is now dispersed throughout the country. Mechanical and chemical control methods have been used against the weed, but biological control is considered the most cost-effective, sustainable and environmentally friendly intervention. Currently, nine biological control agents have been released against water hyacinth in South Africa, and Neochetina eichhorniae Warner (Coleoptera: Curculionidae) is used most widely to control it. However, in some sites, water hyacinth mats have still not been brought under control because of eutrophic waters and cool temperatures. It was therefore necessary to release new biological control agents to complement the impact of N. eichhorniae. Megamelus scutellaris Berg (Hemiptera: Delphacidae) was released in 2013, but little is known about how it interacts with other agents already present in South Africa. It is likely to compete with the established biological control agent, Eccritotarsus eichhorniae Henry (Heteroptera: Miridae), because they are both sap suckers. On the other hand, N. eichhorniae is the most widespread and thus the most important biological control agent for water hyacinth. The aim of this study, then, was to determine the interactions between the two sap-sucking agents in South Africa that presumably occupy similar niches on the plant, and the interaction between M. scutellerais and N. eichhorniae, the most widely distributed and abundant agent in South Africa. Three experiments were conducted at the Waainek Research Facility at Rhodes University, Grahamstown, Eastern Cape, South Africa. Plants were grown for two weeks and insect species were inoculated singly or in combination. Water hyacinth, plant growth parameters and insect parameters were measured every 14 days for a period of 12 weeks. The results of the study showed that feeding by either E. eichhorniae or M. scutellaris had no effect on the feeding of the other agent. Both agents reduced all the measured plant growth parameters equally, either singly or in combination (i.e. E. eichhorniae or M. scutellaris alone or together). The interaction between the two agents appears neutral and agents are likely to complement each other in the field. Prior feeding by E. eichhorniae or M. scutellaris on water hyacinth did not affect the subsequent feeding by either agent. Megamelus scutellaris prefers healthy fresh water hyacinth plants. In addition, planthoppers performed best in combination with the weevil, especially on plants with new weevil feeding scars. The results of the study showed that M. scutellaris is compatible with other biological control agents of water hyacinth that are already established in South Africa. Therefore, the introduction of M. scutellaris may enhance the biological control of water hyacinth in South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Petela, Nomvume
- Date: 2018
- Subjects: Water hyacinth -- South Africa , Water hyacinth -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Curculionidae , Delphacidae , Miridae , Neochetina eichhorniae Warner , Megamelus scutellaris Berg , Eccritotarsus eichhorniae Henry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60676 , vital:27814
- Description: Water hyacinth, Eichhomia crassipes (Mart.) Solms (Pontederiaceae) is a free-floating perennial weed that is regarded as the worst aquatic weed in the world because of its negative impacts on aquatic ecosystems. It is native to the Amazon Basin of South America, but since the late 1800s has spread throughout the world. The first record of the weed in South Africa was noted in 1908 on the Cape Flats and in KwaZulu-Natal, but it is now dispersed throughout the country. Mechanical and chemical control methods have been used against the weed, but biological control is considered the most cost-effective, sustainable and environmentally friendly intervention. Currently, nine biological control agents have been released against water hyacinth in South Africa, and Neochetina eichhorniae Warner (Coleoptera: Curculionidae) is used most widely to control it. However, in some sites, water hyacinth mats have still not been brought under control because of eutrophic waters and cool temperatures. It was therefore necessary to release new biological control agents to complement the impact of N. eichhorniae. Megamelus scutellaris Berg (Hemiptera: Delphacidae) was released in 2013, but little is known about how it interacts with other agents already present in South Africa. It is likely to compete with the established biological control agent, Eccritotarsus eichhorniae Henry (Heteroptera: Miridae), because they are both sap suckers. On the other hand, N. eichhorniae is the most widespread and thus the most important biological control agent for water hyacinth. The aim of this study, then, was to determine the interactions between the two sap-sucking agents in South Africa that presumably occupy similar niches on the plant, and the interaction between M. scutellerais and N. eichhorniae, the most widely distributed and abundant agent in South Africa. Three experiments were conducted at the Waainek Research Facility at Rhodes University, Grahamstown, Eastern Cape, South Africa. Plants were grown for two weeks and insect species were inoculated singly or in combination. Water hyacinth, plant growth parameters and insect parameters were measured every 14 days for a period of 12 weeks. The results of the study showed that feeding by either E. eichhorniae or M. scutellaris had no effect on the feeding of the other agent. Both agents reduced all the measured plant growth parameters equally, either singly or in combination (i.e. E. eichhorniae or M. scutellaris alone or together). The interaction between the two agents appears neutral and agents are likely to complement each other in the field. Prior feeding by E. eichhorniae or M. scutellaris on water hyacinth did not affect the subsequent feeding by either agent. Megamelus scutellaris prefers healthy fresh water hyacinth plants. In addition, planthoppers performed best in combination with the weevil, especially on plants with new weevil feeding scars. The results of the study showed that M. scutellaris is compatible with other biological control agents of water hyacinth that are already established in South Africa. Therefore, the introduction of M. scutellaris may enhance the biological control of water hyacinth in South Africa.
- Full Text:
- Date Issued: 2018
Interrogating teacher leadership development through a formative intervention: a case study in a rural Secondary School in northern Namibia
- Authors: Iyambo, David Kandiwapa
- Date: 2018
- Subjects: Educational leadership -- Namibia , School management and organization -- Namibia , Teachers -- Training of -- Namibia , Cultural Historical Activity Theory
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61547 , vital:28035
- Description: The Namibian education system has undergone major policy shifts from a ‘top-down’ hierarchical leadership practice to a more shared and democratic form of leadership in schools. These policies compel principals and school management team members to involve level-one teachers in decision-making and other leadership roles within their schools and beyond. However, to this end, the goals envisaged by policies for teachers to participate in, and contribute to the overall school leadership activities and decision-making have not been fully realised. This was due to the inherent hierarchy of the ‘top-down’ system and autocratic leadership style which remains powerful within the current school practice. Against this backdrop, this study interrogated how teacher leadership can be developed in a rural Secondary School in northern Namibia. The underlying cultural-historical conditions that promoted or constrained teacher leadership development were surfaced. Opportunities for changes in leadership practices through a formative intervention were developed. Cultural Historical Activity Theory (CHAT) was utilised as a theoretical and analytical framework in this study together with Grant’s Model of Teacher Leadership (2006; 2008; 2010). Five level-one teachers, two school management members and a school board chairperson were selected as research participants by means of a purposive sampling method. Furthermore, the study used document analysis, semi-structured interviews, questionnaires and change laboratory workshops as main tools for data generation. The findings revealed that participants understood the concept of teacher leadership differently and that teachers in the case study school were leading in all four zones of teacher leadership model (Grant, 2006; 2008; 2012) although their roles differed. However, the study also found that teacher leadership development was mostly intensified by managerial structures. It appeared from the findings of this study that conditions such as the role of the school management team (SMT) members in promoting teacher leadership development, a supportive organisational culture, and provision of learning support amongst staff members through the attendance of workshops emerged as factors promoting the development of teachers as leaders. The study also revealed that there were many cultural and historical tensions that constrained the practice of teacher leadership development in school. Thus, the study argues that limited leadership training and an inherent ‘top-down’ hierarchical style of leadership was the main underlying systemic causes that constrained teachers to be developed as leaders. Through the change laboratory workshops, the findings suggested that there was a need for continuous professional development initiatives and leadership training, as alternative way for the realisation of teacher leadership development. Finally, a recommendation that leadership aspects should be constituted in pre-and in-service professional development training as an ongoing practice is made.
- Full Text:
- Date Issued: 2018
- Authors: Iyambo, David Kandiwapa
- Date: 2018
- Subjects: Educational leadership -- Namibia , School management and organization -- Namibia , Teachers -- Training of -- Namibia , Cultural Historical Activity Theory
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61547 , vital:28035
- Description: The Namibian education system has undergone major policy shifts from a ‘top-down’ hierarchical leadership practice to a more shared and democratic form of leadership in schools. These policies compel principals and school management team members to involve level-one teachers in decision-making and other leadership roles within their schools and beyond. However, to this end, the goals envisaged by policies for teachers to participate in, and contribute to the overall school leadership activities and decision-making have not been fully realised. This was due to the inherent hierarchy of the ‘top-down’ system and autocratic leadership style which remains powerful within the current school practice. Against this backdrop, this study interrogated how teacher leadership can be developed in a rural Secondary School in northern Namibia. The underlying cultural-historical conditions that promoted or constrained teacher leadership development were surfaced. Opportunities for changes in leadership practices through a formative intervention were developed. Cultural Historical Activity Theory (CHAT) was utilised as a theoretical and analytical framework in this study together with Grant’s Model of Teacher Leadership (2006; 2008; 2010). Five level-one teachers, two school management members and a school board chairperson were selected as research participants by means of a purposive sampling method. Furthermore, the study used document analysis, semi-structured interviews, questionnaires and change laboratory workshops as main tools for data generation. The findings revealed that participants understood the concept of teacher leadership differently and that teachers in the case study school were leading in all four zones of teacher leadership model (Grant, 2006; 2008; 2012) although their roles differed. However, the study also found that teacher leadership development was mostly intensified by managerial structures. It appeared from the findings of this study that conditions such as the role of the school management team (SMT) members in promoting teacher leadership development, a supportive organisational culture, and provision of learning support amongst staff members through the attendance of workshops emerged as factors promoting the development of teachers as leaders. The study also revealed that there were many cultural and historical tensions that constrained the practice of teacher leadership development in school. Thus, the study argues that limited leadership training and an inherent ‘top-down’ hierarchical style of leadership was the main underlying systemic causes that constrained teachers to be developed as leaders. Through the change laboratory workshops, the findings suggested that there was a need for continuous professional development initiatives and leadership training, as alternative way for the realisation of teacher leadership development. Finally, a recommendation that leadership aspects should be constituted in pre-and in-service professional development training as an ongoing practice is made.
- Full Text:
- Date Issued: 2018
Investigating combinations of feature extraction and classification for improved image-based multimodal biometric systems at the feature level
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Date Issued: 2018
Investigating Grade 3 learners’ changing mathematical proficiency in a maths club programme focused on number sense progression
- Authors: Hebe, Gasenakeletso Ennie
- Date: 2018
- Subjects: Mathematical ability -- Testing , Education, Elementary -- South Africa , Mathematics -- Study and teaching (Elementary) -- Activity programs , Mathematics -- Remedial teaching , South African Numeracy Chair Project (SANCP)
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/62200 , vital:28137
- Description: Recent international reports, for example TIMSS (2011 & 2015), point to serious challenges in South African learner performance in Mathematics and Science. Of greatest concern is that research findings (e.g. Graven, Venkat, Westaway and Tshesane 2013) suggest that many South African learners show signs of mathematical knowledge gaps in the lower grades. Hence, there is a need to address challenges of this nature very early in Foundation Phase. This study was undertaken with a view to contribute towards addressing mathematical challenges encountered by learners in Foundation Phase. This empirical enquiry was undertaken under the auspices of the South African Numeracy Chair Project (SANCP) at Rhodes University whose mission is to develop sustainable ways of improving quality teaching and learning of Mathematics in South Africa. A relatively new SANCP programme called Pushing for Progression (PfP) run as part of the after-school Maths Clubs to develop the number sense and four Operations in learners was used to achieve the research aims of this study. Research participants were drawn from the Maths Clubs established by the researcher in a small rural town of Ottosdal in the North West Province of South Africa. This Study is grounded on the Vygotskian perspective and uses the interpretivist qualitative research method for data collection and analysis. Sampling was done opportunistically by enlisting participants (12 teachers and 117 learners) on the basis of their availability and willingness to participate. Pre- and post-assessment of learners’ proficiency on the four Basic Operations was conducted at the beginning and at the end of the research project, respectively. This was done to determine the impact of the project on learner performance. Data analysis was done thematically and through the comparison of learner results of the pre- and post-assessment. The findings point to the effectiveness of the PfP Programme in learner performance. This can be deduced from improved scores between pre- and post-assessment and the observations made by participant-teachers on their respective club learners’ mathematical proficiencies. Accordingly, based on the findings, this study recommends, inter alia, that since the PfP programme is still in its early stages, similar research be conducted elsewhere. Additionally, the Department of Basic Education could consider exploring the PfP programme as one of several other strategies to help improve learner proficiency in Mathematics.
- Full Text:
- Date Issued: 2018
- Authors: Hebe, Gasenakeletso Ennie
- Date: 2018
- Subjects: Mathematical ability -- Testing , Education, Elementary -- South Africa , Mathematics -- Study and teaching (Elementary) -- Activity programs , Mathematics -- Remedial teaching , South African Numeracy Chair Project (SANCP)
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/62200 , vital:28137
- Description: Recent international reports, for example TIMSS (2011 & 2015), point to serious challenges in South African learner performance in Mathematics and Science. Of greatest concern is that research findings (e.g. Graven, Venkat, Westaway and Tshesane 2013) suggest that many South African learners show signs of mathematical knowledge gaps in the lower grades. Hence, there is a need to address challenges of this nature very early in Foundation Phase. This study was undertaken with a view to contribute towards addressing mathematical challenges encountered by learners in Foundation Phase. This empirical enquiry was undertaken under the auspices of the South African Numeracy Chair Project (SANCP) at Rhodes University whose mission is to develop sustainable ways of improving quality teaching and learning of Mathematics in South Africa. A relatively new SANCP programme called Pushing for Progression (PfP) run as part of the after-school Maths Clubs to develop the number sense and four Operations in learners was used to achieve the research aims of this study. Research participants were drawn from the Maths Clubs established by the researcher in a small rural town of Ottosdal in the North West Province of South Africa. This Study is grounded on the Vygotskian perspective and uses the interpretivist qualitative research method for data collection and analysis. Sampling was done opportunistically by enlisting participants (12 teachers and 117 learners) on the basis of their availability and willingness to participate. Pre- and post-assessment of learners’ proficiency on the four Basic Operations was conducted at the beginning and at the end of the research project, respectively. This was done to determine the impact of the project on learner performance. Data analysis was done thematically and through the comparison of learner results of the pre- and post-assessment. The findings point to the effectiveness of the PfP Programme in learner performance. This can be deduced from improved scores between pre- and post-assessment and the observations made by participant-teachers on their respective club learners’ mathematical proficiencies. Accordingly, based on the findings, this study recommends, inter alia, that since the PfP programme is still in its early stages, similar research be conducted elsewhere. Additionally, the Department of Basic Education could consider exploring the PfP programme as one of several other strategies to help improve learner proficiency in Mathematics.
- Full Text:
- Date Issued: 2018
Investigating the influence of ring substitution on indole hydrogen bonding, with amino acids
- Authors: Nel, Donovan
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63509 , vital:28426
- Description: Expected release date-April 2019
- Full Text: false
- Date Issued: 2018
- Authors: Nel, Donovan
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63509 , vital:28426
- Description: Expected release date-April 2019
- Full Text: false
- Date Issued: 2018
Investigating the viability and performance of a pilot scale Fly Ash/Lime Filter Tower (FLFT) for greywater treatment and the fate of Triclosan post treatment
- Authors: Nondlazi, Sinoyolo
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63704 , vital:28473
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Nondlazi, Sinoyolo
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63704 , vital:28473
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Investigating thermal physiology as a tool to improve the release efficacy of insect biological control agents
- Authors: Griffith, Tamzin Camilla
- Date: 2018
- Subjects: Aquatic weeds -- Biological control , Water hyacinth -- Biological control , Insects -- Physiology , Miridae -- Effect of low temperatures on , Cold adaptation , Insects as biological pest control agents , Eccritotarsus catarinensis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63301 , vital:28391
- Description: Biological control is commonly used for the control of invasive aquatic weeds, which often involves the release of multiple host-specific agents. Releasing multiple agents has inherent safety concerns as the introduction of each new agent is associated with risks, but is often required to improve control where establishment is limited. Climatic incompatibility between the agent’s thermal physiology and its introduced range often causes agents to fail to establish. However, it has been suggested that the thermal physiology of insects is plastic. Therefore, the potential to manipulate their thermal physiologies before releasing them into the field needs to be explored; reducing the need to release additional agents, thereby ensuring the safety of biological control. This thesis therefore aimed to firstly, determine whether season and locality influenced the thermal physiology of two field populations of a water hyacinth (Eichhornia crassipes) control agent, the mirid Eccritotarsus catarinensis; one collected from the hottest establishment site, and one collected from the coldest establishment site in South Africa. Their thermal physiology was significantly influenced by season and not by the sites’ climate, suggesting their thermal physiology is plastic under field conditions. Secondly, the classical method of determining the lower critical thermal limit (CTmin), and a new respirometry method of determining this limit, compared the thermal physiology of two Eccritotarsus species reared in quarantine. Eccritotarsus catarinensis was significantly more cold tolerant than the more recently released Eccritotarsus eichhorniae, despite similar maintenance conditions, and as such, was used to establish whether cold hardening under laboratory conditions was possible. Successfully cold hardened E. catarinensis had a significantly lower CTmin compared to the field cold acclimated population, suggesting that cold hardening of agents could be conducted before release to improve their cold tolerance and increase their chances of establishment, allowing for further adaptation to colder climates in the field to occur. Increasing establishment of the most effective agents will decrease the number of agents needed in a biological control programme, thus encouraging a more parsimonious approach to biological control.
- Full Text:
- Date Issued: 2018
- Authors: Griffith, Tamzin Camilla
- Date: 2018
- Subjects: Aquatic weeds -- Biological control , Water hyacinth -- Biological control , Insects -- Physiology , Miridae -- Effect of low temperatures on , Cold adaptation , Insects as biological pest control agents , Eccritotarsus catarinensis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63301 , vital:28391
- Description: Biological control is commonly used for the control of invasive aquatic weeds, which often involves the release of multiple host-specific agents. Releasing multiple agents has inherent safety concerns as the introduction of each new agent is associated with risks, but is often required to improve control where establishment is limited. Climatic incompatibility between the agent’s thermal physiology and its introduced range often causes agents to fail to establish. However, it has been suggested that the thermal physiology of insects is plastic. Therefore, the potential to manipulate their thermal physiologies before releasing them into the field needs to be explored; reducing the need to release additional agents, thereby ensuring the safety of biological control. This thesis therefore aimed to firstly, determine whether season and locality influenced the thermal physiology of two field populations of a water hyacinth (Eichhornia crassipes) control agent, the mirid Eccritotarsus catarinensis; one collected from the hottest establishment site, and one collected from the coldest establishment site in South Africa. Their thermal physiology was significantly influenced by season and not by the sites’ climate, suggesting their thermal physiology is plastic under field conditions. Secondly, the classical method of determining the lower critical thermal limit (CTmin), and a new respirometry method of determining this limit, compared the thermal physiology of two Eccritotarsus species reared in quarantine. Eccritotarsus catarinensis was significantly more cold tolerant than the more recently released Eccritotarsus eichhorniae, despite similar maintenance conditions, and as such, was used to establish whether cold hardening under laboratory conditions was possible. Successfully cold hardened E. catarinensis had a significantly lower CTmin compared to the field cold acclimated population, suggesting that cold hardening of agents could be conducted before release to improve their cold tolerance and increase their chances of establishment, allowing for further adaptation to colder climates in the field to occur. Increasing establishment of the most effective agents will decrease the number of agents needed in a biological control programme, thus encouraging a more parsimonious approach to biological control.
- Full Text:
- Date Issued: 2018
Isolation, identification and genetic characterisation of a microsporidium isolated from the carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae)
- Authors: Lloyd, Melissa
- Date: 2018
- Subjects: Pyralidae , Pyralidae -- Genetics , Pyralidae -- Phylogeny , Pyralidae -- Pathogens , Cladistic analysis , Transmission electron microscopy , Carob moth (Ectomyelois ceratoniae)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61894 , vital:28075
- Description: Carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae) is an economically important pest, yet its biology and pest status on citrus in South Africa was, until recently, poorly understood. A study was initiated to determine the cause of collapse of a laboratory carob moth colony that was established to investigate the biology of carob moth on citrus and to develop integrated management strategies for the pest. An organism was isolated from deceased larvae and was morphologically identified as a microsporidium, based on transmission electron microscopy. Microsporidia are obligate intracellular parasites that have been found to infect almost all eukaryotes. Several Nosema species have been isolated from economically important insect pests, yet little genetic information is available from online databases for identification. Mature spores were recovered and measured using transmission electron microscopy. Spores were ovocylindrical with a wrinkled exospore, and had a length of 2.8 ± 0.02 pm and a width of 1.6 ± 0.04 pm. The identity of the microsporidium was confirmed by PCR amplification, sequencing and analysis of the regions encoding the ribosomal RNA. BLAST analysis of the different rRNA regions amplified showed that the microsporidium shared a 96 - 99 % identity with Nosema sp. M-Pr, Nosema carpocapsae, Nosema oulemae, Nosema sp. CO1, Microsporidium 57864, and Nosema bombi. Phylogenetic analysis of the SSU and LSU rRNA genes showed that the microsporidium clustered with the Nosema / Vairimorpha clade, supported by a bootstrap value of 100. The organisation of the RNA cistron was determined by PCR amplification using the primer set 18f and L1328r to be 5’-SSU-ITS-LSU-IGS-5S-3’, which confirms the placement of the microsporidium within the Nosema / Vairimorpha clade. Because the BLAST results showed a close relationship with Nosema carpocapsae, a microsporidium infecting codling moth, the pathogenicity of the microsporidium was tested against codling moth by inoculating artificial diet with a high spore concentration of 1.1 x 107 spores/ml and a low spore concentration of 1.1 x 104 spores/ml. DNA was extracted from deceased larvae inoculated with the high concentration, and PCR of the SSU rRNA gene and bacterial 16S region was performed. Mortality in the high concentration experiment was significant (p = 0.05), but the cause of infection was determined to be a bacterium, through sequencing and BLAST analysis of the bacterial 16S rDNA. The bacterium shared a 99 % identity with Bacillus cereus. Percentage mortality (p = 0.09), larval mass (p = 0.09) and instar (p = 0.24) did not differ significantly between treatments in the low concentration experiment. DNA was extracted from the larvae and PCR amplification of the SSU rRNA gene was performed to determine whether microsporidia were present. No SSU bands were observed in any of the treatments and percentage mortality was not significant, thus it was determined that no infection occurred. This is the first study to report the genetic characterisation of a microsporidium isolated from carob moth and provides important genetic information for classification of microsporidia within the Nosema / Vairimorpha clade. It is also one of few studies in which the complete rRNA cistron of a species within the Nosema / Vairimorpha clade has been sequenced. The identification of a microsporidium from a laboratory colony of carob moth is important as it provides information about pathogens infecting the carob moth and constraints to carob moth rearing, which is useful for further studies on rearing carob moth and for establishment of a clean colony for research purposes.
- Full Text:
- Date Issued: 2018
- Authors: Lloyd, Melissa
- Date: 2018
- Subjects: Pyralidae , Pyralidae -- Genetics , Pyralidae -- Phylogeny , Pyralidae -- Pathogens , Cladistic analysis , Transmission electron microscopy , Carob moth (Ectomyelois ceratoniae)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61894 , vital:28075
- Description: Carob moth, Ectomyelois ceratoniae (Zeller) (Lepidoptera: Pyralidae) is an economically important pest, yet its biology and pest status on citrus in South Africa was, until recently, poorly understood. A study was initiated to determine the cause of collapse of a laboratory carob moth colony that was established to investigate the biology of carob moth on citrus and to develop integrated management strategies for the pest. An organism was isolated from deceased larvae and was morphologically identified as a microsporidium, based on transmission electron microscopy. Microsporidia are obligate intracellular parasites that have been found to infect almost all eukaryotes. Several Nosema species have been isolated from economically important insect pests, yet little genetic information is available from online databases for identification. Mature spores were recovered and measured using transmission electron microscopy. Spores were ovocylindrical with a wrinkled exospore, and had a length of 2.8 ± 0.02 pm and a width of 1.6 ± 0.04 pm. The identity of the microsporidium was confirmed by PCR amplification, sequencing and analysis of the regions encoding the ribosomal RNA. BLAST analysis of the different rRNA regions amplified showed that the microsporidium shared a 96 - 99 % identity with Nosema sp. M-Pr, Nosema carpocapsae, Nosema oulemae, Nosema sp. CO1, Microsporidium 57864, and Nosema bombi. Phylogenetic analysis of the SSU and LSU rRNA genes showed that the microsporidium clustered with the Nosema / Vairimorpha clade, supported by a bootstrap value of 100. The organisation of the RNA cistron was determined by PCR amplification using the primer set 18f and L1328r to be 5’-SSU-ITS-LSU-IGS-5S-3’, which confirms the placement of the microsporidium within the Nosema / Vairimorpha clade. Because the BLAST results showed a close relationship with Nosema carpocapsae, a microsporidium infecting codling moth, the pathogenicity of the microsporidium was tested against codling moth by inoculating artificial diet with a high spore concentration of 1.1 x 107 spores/ml and a low spore concentration of 1.1 x 104 spores/ml. DNA was extracted from deceased larvae inoculated with the high concentration, and PCR of the SSU rRNA gene and bacterial 16S region was performed. Mortality in the high concentration experiment was significant (p = 0.05), but the cause of infection was determined to be a bacterium, through sequencing and BLAST analysis of the bacterial 16S rDNA. The bacterium shared a 99 % identity with Bacillus cereus. Percentage mortality (p = 0.09), larval mass (p = 0.09) and instar (p = 0.24) did not differ significantly between treatments in the low concentration experiment. DNA was extracted from the larvae and PCR amplification of the SSU rRNA gene was performed to determine whether microsporidia were present. No SSU bands were observed in any of the treatments and percentage mortality was not significant, thus it was determined that no infection occurred. This is the first study to report the genetic characterisation of a microsporidium isolated from carob moth and provides important genetic information for classification of microsporidia within the Nosema / Vairimorpha clade. It is also one of few studies in which the complete rRNA cistron of a species within the Nosema / Vairimorpha clade has been sequenced. The identification of a microsporidium from a laboratory colony of carob moth is important as it provides information about pathogens infecting the carob moth and constraints to carob moth rearing, which is useful for further studies on rearing carob moth and for establishment of a clean colony for research purposes.
- Full Text:
- Date Issued: 2018
Judging psycholegal reporting in civil court proceedings in the Eastern Cape
- Authors: Marais, Claire Anne
- Date: 2018
- Subjects: Court proceedings -- South Africa -- Eastern Cape , Evidence, Expert -- South Africa -- Eastern Cape , Forensic psychology -- South Africa -- Eastern Cape , Quality Rating Scale (QRS) , Psycholegal reporting -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/62999 , vital:28352
- Description: Purpose: The primary purpose for this research was to evaluate the quality of psycholegal reports, and the qualification of the authors. Previous research had revealed generalised poor practices in psycholegal report writing and the authors seemed unqualified as expert witness. This negatively influenced the impression and usefulness of expert psychological opinion in South African courts. The secondary purpose was to compare the results to those determined by Ireland (2012), which was a useful benchmark study in the UK as her findings corresponded with the literature. Method: This archival research analysed a hand-search sample of 20 reports written by 20 psychologists based nationally. These reports were submitted as expert opinion in civil proceedings in the Grahamstown Division of the Eastern Cape High Court between 2011 and 2016. Ireland and Pinschof’s (2009) measure ‘Quality Rating Scale’ was adapted for a South African context and used to evaluate quantitatively the reports. Focus was on the reports’ contents (fact and opinion), methods, process and overall rating, and the qualification of the authors. Results: Overall, two-thirds of the reports were rated as ‘good’ and ‘very good’. The results were generally more positive than Ireland’s (2012) findings. However, there were practices in the report writing that were deemed detrimental to the quality of the expert’s opinion. This included vague referral questions and unclear basis for concluding opinions and diagnosis. There was also a lack of discussions surrounding the scientific trustworthiness of testing methods and absent ethical considerations. Lastly, the specialised expertise of the experts was not adequately documented. Conclusion: The findings painted a more positive picture of psycholegal reporting in South Africa than illustrated in previous research, which seemingly relied on anecdotes and subjective surveys. This study used a systematic and objective measure. The findings of this study, previous research and ethical Rules of Conduct were used to consider recommendations for psycholegal report writing, and the improvement of the field of psycholegal work. Lastly, the focus of future research was discussed.
- Full Text:
- Date Issued: 2018
- Authors: Marais, Claire Anne
- Date: 2018
- Subjects: Court proceedings -- South Africa -- Eastern Cape , Evidence, Expert -- South Africa -- Eastern Cape , Forensic psychology -- South Africa -- Eastern Cape , Quality Rating Scale (QRS) , Psycholegal reporting -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/62999 , vital:28352
- Description: Purpose: The primary purpose for this research was to evaluate the quality of psycholegal reports, and the qualification of the authors. Previous research had revealed generalised poor practices in psycholegal report writing and the authors seemed unqualified as expert witness. This negatively influenced the impression and usefulness of expert psychological opinion in South African courts. The secondary purpose was to compare the results to those determined by Ireland (2012), which was a useful benchmark study in the UK as her findings corresponded with the literature. Method: This archival research analysed a hand-search sample of 20 reports written by 20 psychologists based nationally. These reports were submitted as expert opinion in civil proceedings in the Grahamstown Division of the Eastern Cape High Court between 2011 and 2016. Ireland and Pinschof’s (2009) measure ‘Quality Rating Scale’ was adapted for a South African context and used to evaluate quantitatively the reports. Focus was on the reports’ contents (fact and opinion), methods, process and overall rating, and the qualification of the authors. Results: Overall, two-thirds of the reports were rated as ‘good’ and ‘very good’. The results were generally more positive than Ireland’s (2012) findings. However, there were practices in the report writing that were deemed detrimental to the quality of the expert’s opinion. This included vague referral questions and unclear basis for concluding opinions and diagnosis. There was also a lack of discussions surrounding the scientific trustworthiness of testing methods and absent ethical considerations. Lastly, the specialised expertise of the experts was not adequately documented. Conclusion: The findings painted a more positive picture of psycholegal reporting in South Africa than illustrated in previous research, which seemingly relied on anecdotes and subjective surveys. This study used a systematic and objective measure. The findings of this study, previous research and ethical Rules of Conduct were used to consider recommendations for psycholegal report writing, and the improvement of the field of psycholegal work. Lastly, the focus of future research was discussed.
- Full Text:
- Date Issued: 2018
Key considerations for novel aptamer generation and aptasensor platform design: a case study on human α-thrombin and histamine as sensor targets
- Authors: Ho, Lance St John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63534 , vital:28432
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Ho, Lance St John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63534 , vital:28432
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018