Examining intraspecific multiple predator effects across shifting predator sex ratios:
- Cuthbert, Ross N, Dalu, Tatenda, Wasserman, Ryan J, Weyl, Olaf L F, Froneman, P William, Callaghan, Amanda, Dick, Jaimie T A
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
- Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
- Full Text:
- Date Issued: 2020
- Authors: Cuthbert, Ross N , Dalu, Tatenda , Wasserman, Ryan J , Weyl, Olaf L F , Froneman, P William , Callaghan, Amanda , Dick, Jaimie T A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150119 , vital:38941 , https://doi.org/10.1016/j.baae.2020.03.002
- Description: Predator-predator interactions, or “multiple predator effects” (MPEs), are pervasive in the structuring of communities and complicate predictive quantifications of ecosystem dynamics. The nature of MPEs is also context-dependent, manifesting differently among species, prey densities and habitat structures. However, there has hitherto been a lack of consideration for the implications of intraspecific demographic variation within populations for the strength of MPEs. The present study extends MPE concepts to examine intraspecific interactions among male and female predators across differences in prey densities using a functional response approach. Focusing on a copepod-mosquito model predator-prey system, interaction strengths of different sex ratio pairs of Lovenula raynerae were quantified towards larval Culex pipiens complex prey, with observations compared to both additive and substitutive model predictions.
- Full Text:
- Date Issued: 2020
Expansive learning in the leadership development of school learners
- Grant, Carolyn, Kajee, Farhana Amod
- Authors: Grant, Carolyn , Kajee, Farhana Amod
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281072 , vital:55689 , xlink:href="https://doi.org/10.1080/13603124.2020.1836405"
- Description: In many countries across the globe, and on the African continent in particular, young people do not have a voice in matters concerning their schooling. By virtue of their minor status, opportunities for participatory decision-making and leadership in schools are restricted, despite national policies to the contrary. This is all-too-often because leadership is (mis)understood as an adult phenomenon. In this article, we present a formative intervention, ‘Learners Lead’, which aimed at developing learner voice and leadership in learners through collective involvement in school change projects. Formulated as a documentary case study, data were generated from 95 research reports, the written assessments of the students registered for the Educational Leadership and Management elective within a postgraduate qualification in a South African university. Analysis drew on the pyramid of learner voice and the theory of expansive learning to examine if, and how, leadership development in learners occurred. The study found that expansive learning’s seven learning actions provided the necessary additional theoretical tools for understanding and unpacking the stages of leadership development as the school change projects unfolded. Implications for practice and research are discussed.
- Full Text:
- Date Issued: 2020
- Authors: Grant, Carolyn , Kajee, Farhana Amod
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/281072 , vital:55689 , xlink:href="https://doi.org/10.1080/13603124.2020.1836405"
- Description: In many countries across the globe, and on the African continent in particular, young people do not have a voice in matters concerning their schooling. By virtue of their minor status, opportunities for participatory decision-making and leadership in schools are restricted, despite national policies to the contrary. This is all-too-often because leadership is (mis)understood as an adult phenomenon. In this article, we present a formative intervention, ‘Learners Lead’, which aimed at developing learner voice and leadership in learners through collective involvement in school change projects. Formulated as a documentary case study, data were generated from 95 research reports, the written assessments of the students registered for the Educational Leadership and Management elective within a postgraduate qualification in a South African university. Analysis drew on the pyramid of learner voice and the theory of expansive learning to examine if, and how, leadership development in learners occurred. The study found that expansive learning’s seven learning actions provided the necessary additional theoretical tools for understanding and unpacking the stages of leadership development as the school change projects unfolded. Implications for practice and research are discussed.
- Full Text:
- Date Issued: 2020
Explored Vygotsky’s concept of mediation in a biliteracy project in the foundation phase of a township school
- Authors: Frans, Nompumelelo Grace
- Date: 2020
- Subjects: Literacy -- South Africa -- Case studies , Education, Elementary -- South Africa -- Case studies , Education, Bilingual -- South Africa -- Case studies , Vygotskiĭ, L S (Lev Semenovich), 1896-1934 , Biliteracy Project (South Africa)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/147204 , vital:38602
- Description: The research reported on in this thesis explored teacher mediation when a biliteracy approach through task-based teaching and learning is used in a Foundation Phase classroom in a township school in the Eastern Cape. It is an action research aimed at understanding and systematically investigating how and what it means to work with bilingual mediation to ensure cognition, with emphasis on task design, facilitation for cognition, mediation forms and language use. This thesis was motivated by three issues that are still not being adequately addressed: the low level of cognitive work in South African schools, the failure to use the home languages of children throughout schooling as a medium of instruction and assessment (while providing excellent access to English as subject), and a top-down approach to both policy development and teacher professionalisation. These three issues drove me to explore theories that can help address them, and that is how I came to rely mostly on mediation, biliteracy and a task-based approach to teaching. For this research, on data handling I prepared and taught six lessons, but only three of the six lessons were recorded, transcribed and analysed for empirical data. I chose data handling, as in my previous experience I found it to include all the mathematical problem-solving skills which involve addition subtraction, analysing and comparing information. It also offered opportunities for language use, and meaningful interactive co-construction and acquiring of knowledge in the process of teaching and learning. This turned into a form of theory-driven action research, which was also developmental. I was critically reflective on my practices, and my facilitation for cognition and how I use language to make cognition possible. I also looked at the types of activities that I gave learners to help reach maximum development. The data collected from the classroom interactions, shows how I, in some instances, would take decisions, implement them and then find them not to be effective. It also shows some of the challenges I came across, from myself and the learners. Learners challenges were, unfamiliarity with the systematic build-up of data handling, filling in tables, transferring information from one form into a different form, and constructing and analysing bar graphs. This was part of pedagogynot the policy, which indicated inadequate teacher development. This could be because data handling is allocated minimal weighting from the CAPS document, and teachers do not go as in depth as they need to in dealing with data handling. My challenge was to prepare the grade 3 class for more data handling encounters in the higher grades. I had to ensure they grasped data handling concepts in their mother tongue before the switch to English as LoLT, as prescribed by policy. Learners proved to have little or no knowledge with regards to data handling concepts, which meant I had to start from the basics, as I had nothing to build on, and then progress to grade 3 level in one year. This study suggests that for any concept that has to be taught, cognition must be a priority, and strategies on how to facilitate that needs to be well thought out. Teachers need to be aware of theories that can positively impact on their practices. Teacher development is key to improvement of education, especially in the Eastern Cape. That cannot be done in isolation, but in partnership with relevant stakeholders.
- Full Text:
- Date Issued: 2020
- Authors: Frans, Nompumelelo Grace
- Date: 2020
- Subjects: Literacy -- South Africa -- Case studies , Education, Elementary -- South Africa -- Case studies , Education, Bilingual -- South Africa -- Case studies , Vygotskiĭ, L S (Lev Semenovich), 1896-1934 , Biliteracy Project (South Africa)
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/147204 , vital:38602
- Description: The research reported on in this thesis explored teacher mediation when a biliteracy approach through task-based teaching and learning is used in a Foundation Phase classroom in a township school in the Eastern Cape. It is an action research aimed at understanding and systematically investigating how and what it means to work with bilingual mediation to ensure cognition, with emphasis on task design, facilitation for cognition, mediation forms and language use. This thesis was motivated by three issues that are still not being adequately addressed: the low level of cognitive work in South African schools, the failure to use the home languages of children throughout schooling as a medium of instruction and assessment (while providing excellent access to English as subject), and a top-down approach to both policy development and teacher professionalisation. These three issues drove me to explore theories that can help address them, and that is how I came to rely mostly on mediation, biliteracy and a task-based approach to teaching. For this research, on data handling I prepared and taught six lessons, but only three of the six lessons were recorded, transcribed and analysed for empirical data. I chose data handling, as in my previous experience I found it to include all the mathematical problem-solving skills which involve addition subtraction, analysing and comparing information. It also offered opportunities for language use, and meaningful interactive co-construction and acquiring of knowledge in the process of teaching and learning. This turned into a form of theory-driven action research, which was also developmental. I was critically reflective on my practices, and my facilitation for cognition and how I use language to make cognition possible. I also looked at the types of activities that I gave learners to help reach maximum development. The data collected from the classroom interactions, shows how I, in some instances, would take decisions, implement them and then find them not to be effective. It also shows some of the challenges I came across, from myself and the learners. Learners challenges were, unfamiliarity with the systematic build-up of data handling, filling in tables, transferring information from one form into a different form, and constructing and analysing bar graphs. This was part of pedagogynot the policy, which indicated inadequate teacher development. This could be because data handling is allocated minimal weighting from the CAPS document, and teachers do not go as in depth as they need to in dealing with data handling. My challenge was to prepare the grade 3 class for more data handling encounters in the higher grades. I had to ensure they grasped data handling concepts in their mother tongue before the switch to English as LoLT, as prescribed by policy. Learners proved to have little or no knowledge with regards to data handling concepts, which meant I had to start from the basics, as I had nothing to build on, and then progress to grade 3 level in one year. This study suggests that for any concept that has to be taught, cognition must be a priority, and strategies on how to facilitate that needs to be well thought out. Teachers need to be aware of theories that can positively impact on their practices. Teacher development is key to improvement of education, especially in the Eastern Cape. That cannot be done in isolation, but in partnership with relevant stakeholders.
- Full Text:
- Date Issued: 2020
Exploring affordances and hindrances when indigenous knowledge is integrated in the topic on waves and sound in a Grade 10 Physical Sciences township class
- Authors: Manyana, Xolani Justice
- Date: 2020
- Subjects: Physical sciences -- Study and teaching (Secondary) -- South Africa , Physical sciences -- Study and teaching (Secondary) -- South Africa -- Case studies , Ethnoscience -- Study and teaching -- South Africa , Schools -- South Africa -- Curricula , Social change
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/142889 , vital:38173
- Description: The lack of interest and hence the decline in the number of learners doing Science in schools, is attributed in part to the decontextualised ways in which Science is taught. As an attempt to address this challenge, the new South African National Curriculum Policy Statement (CAPS) encourages Science teachers to use culturally responsive pedagogies through integrating local or indigenous knowledge (IK) in Science lessons to make it accessible and relevant to learners. But, it does not explicitly state how Science teachers should go about enacting this. It is against this caveat that this study aimed at finding out indigenous practices and knowledge in the community and from two community members that could be integrated into the topic on waves and sound in Grade 10 Physical Sciences lessons with the view to establishing its influence (or not) on learners’ conceptions and dispositions towards Science. The study was conducted at Buyelembo Combined School (pseudonym), a township school in the Sarah Baartman District, in the Eastern Cape in South Africa. The research participants were 18 Grade 10 Physical Sciences learners, two Physical Sciences teachers and two community members. Data were generated using the learners’ group activity, discussions and presentations, observations (participatory observations and lesson observations), stimulated recall interviews and reflections. A thematic and inductive-deductive approach to data analysis was employed to come up with sub-themes and themes. Underpinned by an interpretivist perspective and informed by Vygotsky’s socio-cultural theory, a qualitative case study approach was adopted. Additionally, Ogunniyi’s Contiguity Argumentative Theory (CAT) was used as an analytical framework. The five cognitive states of CAT were employed to analyse data during the social interactions to surface any contradictions. The findings from this study revealed that there are indigenous practices and knowledge in relation to the sea that can be integrated into the topic on waves and sound in Grade 10 Physical Sciences lessons. However, regarding relevance of those indigenous practices and knowledge to science, the study revealed that the learners found no relevance at all but discussions and argumentation were enhanced. In addition, findings from this study revealed that the learners’ conceptions, dispositions, and sense-making in science were influenced positively through using hands-on practical activities when teaching Science concepts. Lastly, the study revealed that the use of mother tongue by the community members, learners and the teachers together with the language of learning and teaching promoted learner talk. Based on the findings of this study, I recommend that there is a need to support teachers on how to integrate indigenous practices and knowledge in their teaching, particularly when teaching Physical Sciences.
- Full Text:
- Date Issued: 2020
- Authors: Manyana, Xolani Justice
- Date: 2020
- Subjects: Physical sciences -- Study and teaching (Secondary) -- South Africa , Physical sciences -- Study and teaching (Secondary) -- South Africa -- Case studies , Ethnoscience -- Study and teaching -- South Africa , Schools -- South Africa -- Curricula , Social change
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/142889 , vital:38173
- Description: The lack of interest and hence the decline in the number of learners doing Science in schools, is attributed in part to the decontextualised ways in which Science is taught. As an attempt to address this challenge, the new South African National Curriculum Policy Statement (CAPS) encourages Science teachers to use culturally responsive pedagogies through integrating local or indigenous knowledge (IK) in Science lessons to make it accessible and relevant to learners. But, it does not explicitly state how Science teachers should go about enacting this. It is against this caveat that this study aimed at finding out indigenous practices and knowledge in the community and from two community members that could be integrated into the topic on waves and sound in Grade 10 Physical Sciences lessons with the view to establishing its influence (or not) on learners’ conceptions and dispositions towards Science. The study was conducted at Buyelembo Combined School (pseudonym), a township school in the Sarah Baartman District, in the Eastern Cape in South Africa. The research participants were 18 Grade 10 Physical Sciences learners, two Physical Sciences teachers and two community members. Data were generated using the learners’ group activity, discussions and presentations, observations (participatory observations and lesson observations), stimulated recall interviews and reflections. A thematic and inductive-deductive approach to data analysis was employed to come up with sub-themes and themes. Underpinned by an interpretivist perspective and informed by Vygotsky’s socio-cultural theory, a qualitative case study approach was adopted. Additionally, Ogunniyi’s Contiguity Argumentative Theory (CAT) was used as an analytical framework. The five cognitive states of CAT were employed to analyse data during the social interactions to surface any contradictions. The findings from this study revealed that there are indigenous practices and knowledge in relation to the sea that can be integrated into the topic on waves and sound in Grade 10 Physical Sciences lessons. However, regarding relevance of those indigenous practices and knowledge to science, the study revealed that the learners found no relevance at all but discussions and argumentation were enhanced. In addition, findings from this study revealed that the learners’ conceptions, dispositions, and sense-making in science were influenced positively through using hands-on practical activities when teaching Science concepts. Lastly, the study revealed that the use of mother tongue by the community members, learners and the teachers together with the language of learning and teaching promoted learner talk. Based on the findings of this study, I recommend that there is a need to support teachers on how to integrate indigenous practices and knowledge in their teaching, particularly when teaching Physical Sciences.
- Full Text:
- Date Issued: 2020
Exploring and modelling the effects of agricultural land management and climate change on agroecosystem services in the Eastern Cape, South Africa
- Authors: Choruma, Dennis Junior
- Date: 2020
- Subjects: Agricultural ecology -- South Africa -- Eastern Cape , Agriculture -- Environmental aspects -- South Africa -- Eastern Cape , Crops and climate -- South Africa -- Eastern Cape , Corn -- Climatic factors -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146756 , vital:38554
- Description: The aims of this study were to evaluate the impacts of agricultural land management strategies and climate change on irrigated maize production in the Eastern Cape, South Africa. To achieve these aims, the study was guided by two overarching research questions, subsequently broken down into more specific questions. The first research question examined the reasons behind farmers’ current agricultural land management practices, the values they assigned to different agroecosystem services, their perceptions of climate change and the adaptation strategies they used to address challenges associated with agricultural crop production and climate change. To answer these questions, a survey of conventional farmers in the Eastern Cape was carried out. The survey targeted farmers who used fertilisers and irrigation water in their day to day farming. Results showed that farmers recognised the different benefits that agroecosystems provided even though they were not familiar with the term ‘ecosystem services.’ Farmers assigned a high value to food provisioning compared to other agroecosystem services and managed their farms for maximum crop yields or maximum crop quality. Fertiliser and irrigation water management decisions were based on multiple factors such as cost, availability of farming equipment and crop yield or crop quality considerations. Survey results showed that while most farmers were able to state the amount of fertiliser used per growing season, the majority of farmers did not know the amount of water they used per growing season. From the farmers’ survey it was recommended that extension services and agricultural education programmes be strengthened in the region to increase farmers’ knowledge on effective agricultural land management strategies that support sustainable intensification. The second research question investigated the effects of agricultural land management strategies and climate change on crop yields in the Eastern Cape. This investigation was done in three steps. First, a crop model, the Environmental Policy Integrated Climate (EPIC) model was calibrated and validated using limited field data from maize variety trials carried out at the Cradock Research Farm in the Eastern Cape. Calibration and validation results proved satisfactory with model efficiencies (Nash Sutcliffe, NSE) greater than 0.5 for both calibration and validation. It was concluded that limited data from field trials on maize that only included grain yield and agricultural land management dates can be used for the calibration of the EPIC model to simulate maize production under South African conditions. In the second step, the calibrated model was applied to simulate different irrigation and fertiliser management strategies for maize production in the Eastern Cape. Different irrigation and Nitrogen (N) fertiliser levels were compared to find optimal irrigation and N fertiliser management strategies that would increase maize yields while minimising environmental pollution (nitrate leaching). Model outputs were also compared to the average yields obtained in the field trials (baseline) and to maize yields reported by farmers in the farmers’ survey. Results showed that improved management of irrigation water and N fertiliser could improve farmers’ maize yields from approximately 7.2 t ha-1 to approximately 12.2 t ha-1, an increase of approximately 69%. Results also revealed a trade-off between food provision and nitrate leaching. Simulations showed that increasing N fertiliser application under sufficient irrigation water levels would increase maize yields, however, this would be accompanied by an increase in N leaching. Lastly, the EPIC model was then applied to simulate the effects of future climate change on irrigated maize production in the Eastern Cape. For these simulations, the model was driven by statistically downscaled climate data derived from three General Circulation Models (GCMs) for two future climate periods, (2040-2069) and (2070-2099), under two Representative Concentration Pathways (RCPs): RCP 4.5 and RCP 8.5. Future maize yields were compared to the baseline (1980-2010) maize yield average. All three climate models predicted a decline in maize yields, with yields declining by as much as 23.8% in RCP 8.5, 2070-2099. Simulations also predicted increases in average daily maximum and minimum temperatures for both the two future climate periods under both RCPs. Results also indicated a decrease in seasonal irrigation water requirements. Nitrate leaching was projected to significantly increase towards the end of the century, increasing by as much as 373.8% in RCP 8.5 2070-2099. Concerning farmers’ perceptions of climate change, results showed that farmers were aware of climate change and identified temperature and rainfall changes as the most important changes in climate that they had observed. To adapt to climate change, farmers used a variety of adaptation strategies such as crop rotations and intercropping. Apart from challenges posed by climate change, farmers also faced other challenges such as access to markets and access to financial credit lines, challenges that prevented them from effectively adapting to climate change. The study therefore recommended that appropriate and adequate strategies be designed to help farmers in the region offset the projected decrease in maize production and increase crop yields while minimising negative environmental impacts.
- Full Text:
- Date Issued: 2020
- Authors: Choruma, Dennis Junior
- Date: 2020
- Subjects: Agricultural ecology -- South Africa -- Eastern Cape , Agriculture -- Environmental aspects -- South Africa -- Eastern Cape , Crops and climate -- South Africa -- Eastern Cape , Corn -- Climatic factors -- South Africa -- Eastern Cape , Land use -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146756 , vital:38554
- Description: The aims of this study were to evaluate the impacts of agricultural land management strategies and climate change on irrigated maize production in the Eastern Cape, South Africa. To achieve these aims, the study was guided by two overarching research questions, subsequently broken down into more specific questions. The first research question examined the reasons behind farmers’ current agricultural land management practices, the values they assigned to different agroecosystem services, their perceptions of climate change and the adaptation strategies they used to address challenges associated with agricultural crop production and climate change. To answer these questions, a survey of conventional farmers in the Eastern Cape was carried out. The survey targeted farmers who used fertilisers and irrigation water in their day to day farming. Results showed that farmers recognised the different benefits that agroecosystems provided even though they were not familiar with the term ‘ecosystem services.’ Farmers assigned a high value to food provisioning compared to other agroecosystem services and managed their farms for maximum crop yields or maximum crop quality. Fertiliser and irrigation water management decisions were based on multiple factors such as cost, availability of farming equipment and crop yield or crop quality considerations. Survey results showed that while most farmers were able to state the amount of fertiliser used per growing season, the majority of farmers did not know the amount of water they used per growing season. From the farmers’ survey it was recommended that extension services and agricultural education programmes be strengthened in the region to increase farmers’ knowledge on effective agricultural land management strategies that support sustainable intensification. The second research question investigated the effects of agricultural land management strategies and climate change on crop yields in the Eastern Cape. This investigation was done in three steps. First, a crop model, the Environmental Policy Integrated Climate (EPIC) model was calibrated and validated using limited field data from maize variety trials carried out at the Cradock Research Farm in the Eastern Cape. Calibration and validation results proved satisfactory with model efficiencies (Nash Sutcliffe, NSE) greater than 0.5 for both calibration and validation. It was concluded that limited data from field trials on maize that only included grain yield and agricultural land management dates can be used for the calibration of the EPIC model to simulate maize production under South African conditions. In the second step, the calibrated model was applied to simulate different irrigation and fertiliser management strategies for maize production in the Eastern Cape. Different irrigation and Nitrogen (N) fertiliser levels were compared to find optimal irrigation and N fertiliser management strategies that would increase maize yields while minimising environmental pollution (nitrate leaching). Model outputs were also compared to the average yields obtained in the field trials (baseline) and to maize yields reported by farmers in the farmers’ survey. Results showed that improved management of irrigation water and N fertiliser could improve farmers’ maize yields from approximately 7.2 t ha-1 to approximately 12.2 t ha-1, an increase of approximately 69%. Results also revealed a trade-off between food provision and nitrate leaching. Simulations showed that increasing N fertiliser application under sufficient irrigation water levels would increase maize yields, however, this would be accompanied by an increase in N leaching. Lastly, the EPIC model was then applied to simulate the effects of future climate change on irrigated maize production in the Eastern Cape. For these simulations, the model was driven by statistically downscaled climate data derived from three General Circulation Models (GCMs) for two future climate periods, (2040-2069) and (2070-2099), under two Representative Concentration Pathways (RCPs): RCP 4.5 and RCP 8.5. Future maize yields were compared to the baseline (1980-2010) maize yield average. All three climate models predicted a decline in maize yields, with yields declining by as much as 23.8% in RCP 8.5, 2070-2099. Simulations also predicted increases in average daily maximum and minimum temperatures for both the two future climate periods under both RCPs. Results also indicated a decrease in seasonal irrigation water requirements. Nitrate leaching was projected to significantly increase towards the end of the century, increasing by as much as 373.8% in RCP 8.5 2070-2099. Concerning farmers’ perceptions of climate change, results showed that farmers were aware of climate change and identified temperature and rainfall changes as the most important changes in climate that they had observed. To adapt to climate change, farmers used a variety of adaptation strategies such as crop rotations and intercropping. Apart from challenges posed by climate change, farmers also faced other challenges such as access to markets and access to financial credit lines, challenges that prevented them from effectively adapting to climate change. The study therefore recommended that appropriate and adequate strategies be designed to help farmers in the region offset the projected decrease in maize production and increase crop yields while minimising negative environmental impacts.
- Full Text:
- Date Issued: 2020
Exploring career information through developmental contextual focus groups with youth from disadvantaged backgrounds
- Authors: Phala, Phorogohlo Modipadi
- Date: 2020
- Subjects: Vocational guidance , Educational counseling , Focus groups , Action research , Youth -- South Africa -- Social conditions -- 1994- , Parental influences – South Africa , Vocational guidance -- Parent participation -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/130594 , vital:36442
- Description: This study investigates the importance of initiating career exploration discussions with young people from disadvantaged backgrounds, using the developmental-contextual framework of career development by Vondracek, Lerner & Schulenburg (1986). This model stresses the dynamic relationship between an individual, the ever-changing environment and how each influences the other. Based upon an earlier study by Spencer (1999), this study aims to explore the developmental-contextual model as the basis of successive group discussions at a pivotal moment in the lives of the youth from disadvantaged backgrounds. In addition, it aims to understand individuals’ perceptions of career education and the influences on career decision-making and aspiration. Data were collected through setting up and running a focus group session once a week over a period of five weeks, in which different career-related topics were discussed. The sample consisted of nine unemployed students who were currently not in a tertiary institution between the ages of 18-25 years. The findings indicated a noteworthy need for more relevant career interventions to be investigated and implemented for the diverse South African population. The study’s findings demonstrated that individuals might be more open to exploring career development through group rather than individual counselling. It was found that parents are the main career influencers in their children’s lives. Mothers were experienced as role models, supporters and encouragers while fathers were experienced as absent and unsupportive, playing little or no role in their children’s lives. The participants found this form of career exploration appealing as it allowed for peer consultation and the freedom to discuss career issues in a non-judgemental setting.
- Full Text:
- Date Issued: 2020
- Authors: Phala, Phorogohlo Modipadi
- Date: 2020
- Subjects: Vocational guidance , Educational counseling , Focus groups , Action research , Youth -- South Africa -- Social conditions -- 1994- , Parental influences – South Africa , Vocational guidance -- Parent participation -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/130594 , vital:36442
- Description: This study investigates the importance of initiating career exploration discussions with young people from disadvantaged backgrounds, using the developmental-contextual framework of career development by Vondracek, Lerner & Schulenburg (1986). This model stresses the dynamic relationship between an individual, the ever-changing environment and how each influences the other. Based upon an earlier study by Spencer (1999), this study aims to explore the developmental-contextual model as the basis of successive group discussions at a pivotal moment in the lives of the youth from disadvantaged backgrounds. In addition, it aims to understand individuals’ perceptions of career education and the influences on career decision-making and aspiration. Data were collected through setting up and running a focus group session once a week over a period of five weeks, in which different career-related topics were discussed. The sample consisted of nine unemployed students who were currently not in a tertiary institution between the ages of 18-25 years. The findings indicated a noteworthy need for more relevant career interventions to be investigated and implemented for the diverse South African population. The study’s findings demonstrated that individuals might be more open to exploring career development through group rather than individual counselling. It was found that parents are the main career influencers in their children’s lives. Mothers were experienced as role models, supporters and encouragers while fathers were experienced as absent and unsupportive, playing little or no role in their children’s lives. The participants found this form of career exploration appealing as it allowed for peer consultation and the freedom to discuss career issues in a non-judgemental setting.
- Full Text:
- Date Issued: 2020
Exploring how a genetic attribution to disease relates to stigma experiences of Xhosa patients with schizophrenia in South Africa
- Matshabane, Olivia P, Campbell, Megan, Faure, Marlyn C, Marshall, Patricia A, Mayosi, Bongani M, Stein, Dan J, Appelbaum, Paul S, de Vries, Jantina
- Authors: Matshabane, Olivia P , Campbell, Megan , Faure, Marlyn C , Marshall, Patricia A , Mayosi, Bongani M , Stein, Dan J , Appelbaum, Paul S , de Vries, Jantina
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302487 , vital:58201 , xlink:href="https://doi.org/10.1007/s00127-020-01875-z"
- Description: Background: Over the past three decades, a range of international stakeholders have highlighted the possibility that genomic research may impact stigma associated with psychiatric disorders. Limited research has been conducted in Africa to investigate this relation. Method In the present study, using focus group discussions, we explored the relation between genetic attribution and stigma among 36 Xhosa people with schizophrenia. We addressed three main questions: (1) What causal beliefs do Xhosa people with schizophrenia use to explain their illness and to what extent do genetic explanations play a role in these beliefs? (2) What are the internalised stigma experiences of Xhosa people with schizophrenia? (3) How do genetic explanations relate to stigma experiences, if at all? Results Most participants were able to define genetics and some linked genetics to disease causation. Despite adequate knowledge of genetics and an emphasis on genetic explanations of schizophrenia in the study, most participants held a multitude of causal explanations including: psychosocial, environmental, and cultural. Moreover, participants rarely mentioned disease cause when describing their stigma experiences. Discussion For this population group, there was no straight-forward relation between a genetic attribution and stigma. Therefore, we did not fnd evidence that genetic attribution may signifcantly increase stigma. Although North American and European literature provides conficting evidence regarding this relation, there is increased consensus that biomedical explanations for psychiatric disorders may reduce blame. This study found evidence supporting that consensus. This study provides an empirical foundation to inform ongoing work on the psychosocial implications of psychiatric genomics research in non-Western contexts.
- Full Text:
- Date Issued: 2020
- Authors: Matshabane, Olivia P , Campbell, Megan , Faure, Marlyn C , Marshall, Patricia A , Mayosi, Bongani M , Stein, Dan J , Appelbaum, Paul S , de Vries, Jantina
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/302487 , vital:58201 , xlink:href="https://doi.org/10.1007/s00127-020-01875-z"
- Description: Background: Over the past three decades, a range of international stakeholders have highlighted the possibility that genomic research may impact stigma associated with psychiatric disorders. Limited research has been conducted in Africa to investigate this relation. Method In the present study, using focus group discussions, we explored the relation between genetic attribution and stigma among 36 Xhosa people with schizophrenia. We addressed three main questions: (1) What causal beliefs do Xhosa people with schizophrenia use to explain their illness and to what extent do genetic explanations play a role in these beliefs? (2) What are the internalised stigma experiences of Xhosa people with schizophrenia? (3) How do genetic explanations relate to stigma experiences, if at all? Results Most participants were able to define genetics and some linked genetics to disease causation. Despite adequate knowledge of genetics and an emphasis on genetic explanations of schizophrenia in the study, most participants held a multitude of causal explanations including: psychosocial, environmental, and cultural. Moreover, participants rarely mentioned disease cause when describing their stigma experiences. Discussion For this population group, there was no straight-forward relation between a genetic attribution and stigma. Therefore, we did not fnd evidence that genetic attribution may signifcantly increase stigma. Although North American and European literature provides conficting evidence regarding this relation, there is increased consensus that biomedical explanations for psychiatric disorders may reduce blame. This study found evidence supporting that consensus. This study provides an empirical foundation to inform ongoing work on the psychosocial implications of psychiatric genomics research in non-Western contexts.
- Full Text:
- Date Issued: 2020
Exploring intermolecular contacts in multi-substituted benzaldehyde derivatives: X-ray, Hirshfeld surface and lattice energy analyses
- Hulushe, Siya T, Manyeruke, Meloddy H, Louzada, Marcel, Rigin, Sergei, Hosten, Eric C, Watkins, Gareth M
- Authors: Hulushe, Siya T , Manyeruke, Meloddy H , Louzada, Marcel , Rigin, Sergei , Hosten, Eric C , Watkins, Gareth M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148483 , vital:38743 , DOI: 10.1039/C9RA10752E
- Description: Crystal structures of six benzaldehyde derivatives (1–6) have been determined and their supramolecular networks were established by an X-ray crystallographic study. The study has shown that the compounds are linked by various intermolecular interactions such as weak C–H⋯O hydrogen bonding, and C–H⋯π, π–π and halogen bonding interactions which consolidate and strengthen the formation of these molecular assemblies. The carbonyl group generates diverse synthons in 1–6 via intermolecular C–H⋯O hydrogen bonds. An interplay of C–H⋯O hydrogen bonds, and C–H⋯π and π–π stacking interactions facilitates the formation of multi-dimensional supramolecular networks. Crystal packings in 4 and 5 are further generated by type I halogen⋯halogen bonding interactions. The differences in crystal packing are represented by variation of substitution positions in the compounds. Structure 3 is isomorphous with 4 but there are subtle differences in their crystal packing.
- Full Text:
- Date Issued: 2020
- Authors: Hulushe, Siya T , Manyeruke, Meloddy H , Louzada, Marcel , Rigin, Sergei , Hosten, Eric C , Watkins, Gareth M
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148483 , vital:38743 , DOI: 10.1039/C9RA10752E
- Description: Crystal structures of six benzaldehyde derivatives (1–6) have been determined and their supramolecular networks were established by an X-ray crystallographic study. The study has shown that the compounds are linked by various intermolecular interactions such as weak C–H⋯O hydrogen bonding, and C–H⋯π, π–π and halogen bonding interactions which consolidate and strengthen the formation of these molecular assemblies. The carbonyl group generates diverse synthons in 1–6 via intermolecular C–H⋯O hydrogen bonds. An interplay of C–H⋯O hydrogen bonds, and C–H⋯π and π–π stacking interactions facilitates the formation of multi-dimensional supramolecular networks. Crystal packings in 4 and 5 are further generated by type I halogen⋯halogen bonding interactions. The differences in crystal packing are represented by variation of substitution positions in the compounds. Structure 3 is isomorphous with 4 but there are subtle differences in their crystal packing.
- Full Text:
- Date Issued: 2020
Exploring socialities on Black Twitter: an ethnographic study of everyday concerns of South African users in 2018 and 2019
- Authors: Adebayo, Binwe
- Date: 2020
- Subjects: Twitter (Firm) , Social media South Africa , Social media and society South Africa , Black people and mass media South Africa , Language and the Internet South Africa , Mass media and culture South Africa , Race in mass media , Ethnicity in mass media , Mass media and minorities South Africa , Mass media Social aspects South Africa , Sex differences in mass media , Social media Political aspects South Africa , South Africa Social conditions , Finance In mass media , Intersectionality (Sociology) South Africa , Black Twitter
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140575 , vital:37900
- Description: In this thesis, I examine the phenomenon of Black Twitter, as it exists in South Africa. Drawing on its socio-cultural and linguistic elements, I analyse the kinds of socialities which are constituted on the platform. In the study, I do this by focusing on the key issues which drive the space by evaluating the key everyday concerns as expressed by its users. As such, the overarching lens focuses on three elements: Firstly, the idea of socialities and the way in which they manifest in online spaces; a focus on the everyday as an important site for social inquiry; and lastly the issue of ‘blackness’, in terms of the way it is used and understood in the South African Black Twitter context. Historically, the Black Twitter space has been linked almost exclusively to its broad base of African American users, who are significant both in terms of their numbers, and their impact on online social culture. However, in this study I engage with the ways in which Black Twitter has been adopted, co-opted and used by young South Africans. As a bona fide ‘member’ of South African Black Twitter, my approach to the study was cyberethnographic. Drawing on my access to the space, my knowledge of many of its members and dynamics, I engaged in participant observation as my primary methodology. My discussion focuses on three areas of everyday concerns, namely: gender and sexuality; race and politics; finances and the economy. These three areas emerge both as prominent sites of discussion, but also give the best insight into the ways in which young South Africans are grappling with these issues. My analysis focuses on how everyday concerns are handled on the platform, and I focus on the deployment of solidarity, formal language, platform-based language and the invocation of blackness. I argue in my conclusion that while the structure of the broad Black Twitter space reflects a leaning towards a digital public sphere, that the process and construction of Black Twitter’s ideas and content are approached via an incomplete, fluid convivial approach.
- Full Text:
- Date Issued: 2020
- Authors: Adebayo, Binwe
- Date: 2020
- Subjects: Twitter (Firm) , Social media South Africa , Social media and society South Africa , Black people and mass media South Africa , Language and the Internet South Africa , Mass media and culture South Africa , Race in mass media , Ethnicity in mass media , Mass media and minorities South Africa , Mass media Social aspects South Africa , Sex differences in mass media , Social media Political aspects South Africa , South Africa Social conditions , Finance In mass media , Intersectionality (Sociology) South Africa , Black Twitter
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140575 , vital:37900
- Description: In this thesis, I examine the phenomenon of Black Twitter, as it exists in South Africa. Drawing on its socio-cultural and linguistic elements, I analyse the kinds of socialities which are constituted on the platform. In the study, I do this by focusing on the key issues which drive the space by evaluating the key everyday concerns as expressed by its users. As such, the overarching lens focuses on three elements: Firstly, the idea of socialities and the way in which they manifest in online spaces; a focus on the everyday as an important site for social inquiry; and lastly the issue of ‘blackness’, in terms of the way it is used and understood in the South African Black Twitter context. Historically, the Black Twitter space has been linked almost exclusively to its broad base of African American users, who are significant both in terms of their numbers, and their impact on online social culture. However, in this study I engage with the ways in which Black Twitter has been adopted, co-opted and used by young South Africans. As a bona fide ‘member’ of South African Black Twitter, my approach to the study was cyberethnographic. Drawing on my access to the space, my knowledge of many of its members and dynamics, I engaged in participant observation as my primary methodology. My discussion focuses on three areas of everyday concerns, namely: gender and sexuality; race and politics; finances and the economy. These three areas emerge both as prominent sites of discussion, but also give the best insight into the ways in which young South Africans are grappling with these issues. My analysis focuses on how everyday concerns are handled on the platform, and I focus on the deployment of solidarity, formal language, platform-based language and the invocation of blackness. I argue in my conclusion that while the structure of the broad Black Twitter space reflects a leaning towards a digital public sphere, that the process and construction of Black Twitter’s ideas and content are approached via an incomplete, fluid convivial approach.
- Full Text:
- Date Issued: 2020
Exploring teaching and learning German as a foreign language at a South African institution of higher education: blended learning and collocations
- Authors: Ortner, Gwyndolen Jeanie
- Date: 2020
- Subjects: German language -- Study and teaching (Higher) -- South Africa , German language -- Study and teaching (Higher) -- Foreign speakers -- South Africa , German language -- Study and teaching (Higher) -- English speakers -- South Africa , Rhodes University -- Students , Rhodes University. German Studies
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167295 , vital:41465
- Description: German Studies students at Rhodes University have normally never studied the German language before enrolling for the first-year course and face the challenge of a fairly rapid linguistic advancement, in a context with very limited exposure to the foreign language outside the classroom. Free writing is an area which students find particularly challenging as it requires students to syndissertatione grammatical and vocabulary knowledge. Furthermore, South African students are often underprepared for the challenges they face at university regarding language, technology and finance, as they try to to assimilate to the academic environment and gain epistemological access to their various subjects, in this case, language acquisition and the attendant modules of translation, literature and cultural studies. The use of technology in teaching and learning, known as blended learning, is said to produce better results than face-to face teaching alone, through creating opportunities for more autonomous student learning. Scholars of instructed second-language acquisition also suggest using technology to improve language instruction. One particular area which is gaining ground is teaching students collocational structures through exploring large language corpora, to improve students’ language competencies such as writing fluency. However, both blended learning practices and corpus-based teaching practices suggested by scholars are often not reported on in a particular teaching and learning context, taking into account factors such as institutional infrastructure, student and staff backgrounds and preparedness, and larger socio-political factors. Thus, it remains unclear how these practices (blended learning and corpus-based teaching of collocations) may be integrated into standard urricula, particularly for languages other than English, which have been severely under-researched. The purpose of this research is to take a context-based approach to language teaching and thereby investigate current blended learning practices for German Studies at Rhodes University in South Africa and explore through an action research approach how to integrate collocational awareness into the curriculum, within the blended learning model. Insights from corpus linguistics guide an adaptation of teaching practice, helping students develop skills to aid with writing fluency, seeking to make the patterned nature of language salient to our students. This is undertaken in a scaffolded way, within the curriculum, making use firstly of the texts to which students are exposed in the textbook (comprehensible input) as a source of collocational examples, and following this by making use of reallife language data from an online German corpus, DWDS. Findings from the study reveal a number of best practices related to the use of blended learning and teaching collocations in context of the German foreign language curriculum at a South African institution of higher education.
- Full Text:
- Date Issued: 2020
- Authors: Ortner, Gwyndolen Jeanie
- Date: 2020
- Subjects: German language -- Study and teaching (Higher) -- South Africa , German language -- Study and teaching (Higher) -- Foreign speakers -- South Africa , German language -- Study and teaching (Higher) -- English speakers -- South Africa , Rhodes University -- Students , Rhodes University. German Studies
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167295 , vital:41465
- Description: German Studies students at Rhodes University have normally never studied the German language before enrolling for the first-year course and face the challenge of a fairly rapid linguistic advancement, in a context with very limited exposure to the foreign language outside the classroom. Free writing is an area which students find particularly challenging as it requires students to syndissertatione grammatical and vocabulary knowledge. Furthermore, South African students are often underprepared for the challenges they face at university regarding language, technology and finance, as they try to to assimilate to the academic environment and gain epistemological access to their various subjects, in this case, language acquisition and the attendant modules of translation, literature and cultural studies. The use of technology in teaching and learning, known as blended learning, is said to produce better results than face-to face teaching alone, through creating opportunities for more autonomous student learning. Scholars of instructed second-language acquisition also suggest using technology to improve language instruction. One particular area which is gaining ground is teaching students collocational structures through exploring large language corpora, to improve students’ language competencies such as writing fluency. However, both blended learning practices and corpus-based teaching practices suggested by scholars are often not reported on in a particular teaching and learning context, taking into account factors such as institutional infrastructure, student and staff backgrounds and preparedness, and larger socio-political factors. Thus, it remains unclear how these practices (blended learning and corpus-based teaching of collocations) may be integrated into standard urricula, particularly for languages other than English, which have been severely under-researched. The purpose of this research is to take a context-based approach to language teaching and thereby investigate current blended learning practices for German Studies at Rhodes University in South Africa and explore through an action research approach how to integrate collocational awareness into the curriculum, within the blended learning model. Insights from corpus linguistics guide an adaptation of teaching practice, helping students develop skills to aid with writing fluency, seeking to make the patterned nature of language salient to our students. This is undertaken in a scaffolded way, within the curriculum, making use firstly of the texts to which students are exposed in the textbook (comprehensible input) as a source of collocational examples, and following this by making use of reallife language data from an online German corpus, DWDS. Findings from the study reveal a number of best practices related to the use of blended learning and teaching collocations in context of the German foreign language curriculum at a South African institution of higher education.
- Full Text:
- Date Issued: 2020
Exploring the influence of marine science camps on learners’ motivation and dispositions towards scientific inquiry
- Authors: Hambaze, Nozipiwo
- Date: 2020
- Subjects: Science projects , Marine sciences -- Study and teaching -- South Africa -- Case studies , Active learning , Science camps -- South Africa -- Case studies , Experiential learning , Science -- Study and teaching -- South Africa -- Case studies , Motivation in education -- South Africa -- Case studies
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/163626 , vital:41062
- Description: For a number of years, it has been observed that learners’ motivation towards science has decreased , especially when th ey get to higher grades in secondary school. Strengthening learners’ motivation has become a very important area for educators to understand and reflect on. Many studies suggest that inquiry - based learning activities can provide a conducive learning enviro nment and build up learners ’ abilities and motivation to learn science beyond the classroom. It is against this backdrop that t his interventionist study s ought to investigate the influence of marine science camps on learners’ motivation towards scientific inquiry. The study was informed by Vygotsky ’s social constructivist theory and Wenger ’s community of practice theory. The participants were 21 grade 10 science learners from seven high schools in the Eastern Cape in South Africa. In order to answer the research questions , data w ere collected through the use of Student Motivation T owards Science Learning (SMTSL) questionnaires prior and post science camp, learner reflection journals and focus group interviews. Excel was used to analyse quantitative data w hereas an inductive - deductive thematic approach was used to analyse the qualitative data.The findin gs of the study revealed that through active participation learners’ dispositions shifted and became more positive after the scientific inquiry activity experience at the marine science camp. Furthermore , the findings of the study revealed that as a result of the marine science camp experiences learners were highly motivated to develop their own marine related science projects for the science fairs. Science fairs bear the testimony as one learner did not only co nduct a marine related project for a science fair but was awarded a gold medal at a regional science fair and a silver medal the national fair. The same lea r ne r was awarded an opportunity to present his project in other international fair. Notably also, l earners displayed increase science motivation as a result of participating at the marine science camp. iv This study thus recommends that i n order to enhance scie ntific inquiry among science learners, efforts in developing out - of - school programs not only by th e department of education but also other stakeholders such as universities are needed to inspire and motivate more learners in sciences. Additionally , pure sc ience faculties and social science s should work closely with each other to promote science.
- Full Text:
- Date Issued: 2020
- Authors: Hambaze, Nozipiwo
- Date: 2020
- Subjects: Science projects , Marine sciences -- Study and teaching -- South Africa -- Case studies , Active learning , Science camps -- South Africa -- Case studies , Experiential learning , Science -- Study and teaching -- South Africa -- Case studies , Motivation in education -- South Africa -- Case studies
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/163626 , vital:41062
- Description: For a number of years, it has been observed that learners’ motivation towards science has decreased , especially when th ey get to higher grades in secondary school. Strengthening learners’ motivation has become a very important area for educators to understand and reflect on. Many studies suggest that inquiry - based learning activities can provide a conducive learning enviro nment and build up learners ’ abilities and motivation to learn science beyond the classroom. It is against this backdrop that t his interventionist study s ought to investigate the influence of marine science camps on learners’ motivation towards scientific inquiry. The study was informed by Vygotsky ’s social constructivist theory and Wenger ’s community of practice theory. The participants were 21 grade 10 science learners from seven high schools in the Eastern Cape in South Africa. In order to answer the research questions , data w ere collected through the use of Student Motivation T owards Science Learning (SMTSL) questionnaires prior and post science camp, learner reflection journals and focus group interviews. Excel was used to analyse quantitative data w hereas an inductive - deductive thematic approach was used to analyse the qualitative data.The findin gs of the study revealed that through active participation learners’ dispositions shifted and became more positive after the scientific inquiry activity experience at the marine science camp. Furthermore , the findings of the study revealed that as a result of the marine science camp experiences learners were highly motivated to develop their own marine related science projects for the science fairs. Science fairs bear the testimony as one learner did not only co nduct a marine related project for a science fair but was awarded a gold medal at a regional science fair and a silver medal the national fair. The same lea r ne r was awarded an opportunity to present his project in other international fair. Notably also, l earners displayed increase science motivation as a result of participating at the marine science camp. iv This study thus recommends that i n order to enhance scie ntific inquiry among science learners, efforts in developing out - of - school programs not only by th e department of education but also other stakeholders such as universities are needed to inspire and motivate more learners in sciences. Additionally , pure sc ience faculties and social science s should work closely with each other to promote science.
- Full Text:
- Date Issued: 2020
Exploring the structural integrity of a picornavirus capsid
- Authors: Upfold, Nicole Sarah
- Date: 2020
- Subjects: Picornaviruses , Immunoglobulins , Capsids (Virology) , Viruses Morphology , RNA viruses
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/131837 , vital:36758 , DOI https://doi.org/10.21504/10962/131837
- Description: Picornaviruses are a diverse family of small RNA viruses that cause a broad range of human and veterinary diseases. Despite decades of research into the molecular biology of these pathogens, no antivirals and few vaccines are commercially available for the treatment and prevention of picornavirus infections. The capsids of these non-enveloped viruses are involved in many important aspects of the picornavirus lifecycle, such as cell attachment and entry, uncoating, and protection of the viral RNA. Although the structures of many picornavirus capsids have been solved, a broader understanding of the molecular determinants that are required for structural integrity and stability is imperative for an improved understanding of the basic biology of these viruses, and for designing effective control strategies. Collectively, this thesis aims to elucidate the molecular determinants of structural stability and integrity in the Theiler’s murine encephalomyelitis virus capsid (TMEV). To study the TMEV GDVII capsid using biochemical techniques, neutralising polyclonal antibodies were generated against GDVII particles. The antibodies recognised linear epitopes in the C-terminus of the VP1 protein, but not those present in VP2 or VP3. The VP1 C-terminal residues were mapped to a loop above the putative receptor binding pit on the capsid surface, which prompted an investigation into the potential binding site of the TMEV co-receptor, heparan sulphate. Molecular docking revealed that heparan interacts with residues of the receptor binding pocket, as well as residues of the adjoining VP1 C-terminal loop. These findings suggest that the antibodies neutralise virus infection by preventing attachment of the virus to the co-receptor and possibly the unknown primary receptor. Few studies have identified the specific residues and interactions at subunit interfaces that significantly contribute to picornavirus capsid stability, assembly, and function. A novel in-silico screen was developed for the prediction of hotspot residues at protein-protein interfaces of a virus capsid. This screen can be applied to elucidate the residues that contribute significantly to the intraprotomer, interprotomer and interpentamer interfaces of any picornavirus capsid, on condition that the structure of the virus is available. The screen was applied to TMEV GDVII resulting in the identification of hotspots, several of which correspond to residues that are known to be important for aspects of the virus lifecycle, such as those that contribute to pH stability or form part of receptor binding sites. This observation suggests that residues involved in specific capsid functions may also play a role in capsid stability. Many of the residues identified as hotspots in TMEV corresponded to those required for assembly, uncoating, and virus growth in representative picornaviruses from various genera, suggesting that the residues that regulate capsid stability may be somewhat conserved across the family. Hotspots identified at the interpentamer interfaces of TMEV were individually substituted to alanine to further explore their importance to the TMEV lifecycle. All the amino acid substitutions prevented completion of the virus lifecycle as no CPE was observed following transfection of susceptible cells. Immunofluorescence experiments demonstrated that virus protein synthesis and RNA replication were not inhibited by substitution of the hotspot residues, but that infectivity was severely impeded. This confirmed that the residues were required for some aspect of the virus lifecycle, such as capsid assembly, or were critical for maintaining the conformational stability of the TMEV particles. Virus capsids become unstable and are prone to dissociation under certain conditions such as extreme pH and non-physiological temperatures. The thermostability of TMEV was explored by selecting GDVII virions with improved thermal tolerance through serial passage and heat exposure. Thermostable virions that could tolerate temperatures above 57 °C had reduced infective titres compared to the wild type TMEV suggesting that the virus adapted to thermal stress at the expense of viral fitness. Sequencing the capsid encoding regions of the mutant virions revealed a pair of amino acid substitutions that were present in all mutants. Additional substitutions that were unique to viruses selected at different temperatures were also identified. Most of the substitutions were located within the intraprotomer interfaces of the virus, unlike previous studies on enteroviruses where mutations were mostly localised to the receptor binding pocket. This thesis provides the first analysis of the structural determinants of TMEV capsid stability. The generation of tools to further explore the capsid structures of TMEV and other picornaviruses provides an opportunity for future studies which may contribute to the development of novel control strategies against this important family of viruses. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text: false
- Date Issued: 2020
- Authors: Upfold, Nicole Sarah
- Date: 2020
- Subjects: Picornaviruses , Immunoglobulins , Capsids (Virology) , Viruses Morphology , RNA viruses
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/131837 , vital:36758 , DOI https://doi.org/10.21504/10962/131837
- Description: Picornaviruses are a diverse family of small RNA viruses that cause a broad range of human and veterinary diseases. Despite decades of research into the molecular biology of these pathogens, no antivirals and few vaccines are commercially available for the treatment and prevention of picornavirus infections. The capsids of these non-enveloped viruses are involved in many important aspects of the picornavirus lifecycle, such as cell attachment and entry, uncoating, and protection of the viral RNA. Although the structures of many picornavirus capsids have been solved, a broader understanding of the molecular determinants that are required for structural integrity and stability is imperative for an improved understanding of the basic biology of these viruses, and for designing effective control strategies. Collectively, this thesis aims to elucidate the molecular determinants of structural stability and integrity in the Theiler’s murine encephalomyelitis virus capsid (TMEV). To study the TMEV GDVII capsid using biochemical techniques, neutralising polyclonal antibodies were generated against GDVII particles. The antibodies recognised linear epitopes in the C-terminus of the VP1 protein, but not those present in VP2 or VP3. The VP1 C-terminal residues were mapped to a loop above the putative receptor binding pit on the capsid surface, which prompted an investigation into the potential binding site of the TMEV co-receptor, heparan sulphate. Molecular docking revealed that heparan interacts with residues of the receptor binding pocket, as well as residues of the adjoining VP1 C-terminal loop. These findings suggest that the antibodies neutralise virus infection by preventing attachment of the virus to the co-receptor and possibly the unknown primary receptor. Few studies have identified the specific residues and interactions at subunit interfaces that significantly contribute to picornavirus capsid stability, assembly, and function. A novel in-silico screen was developed for the prediction of hotspot residues at protein-protein interfaces of a virus capsid. This screen can be applied to elucidate the residues that contribute significantly to the intraprotomer, interprotomer and interpentamer interfaces of any picornavirus capsid, on condition that the structure of the virus is available. The screen was applied to TMEV GDVII resulting in the identification of hotspots, several of which correspond to residues that are known to be important for aspects of the virus lifecycle, such as those that contribute to pH stability or form part of receptor binding sites. This observation suggests that residues involved in specific capsid functions may also play a role in capsid stability. Many of the residues identified as hotspots in TMEV corresponded to those required for assembly, uncoating, and virus growth in representative picornaviruses from various genera, suggesting that the residues that regulate capsid stability may be somewhat conserved across the family. Hotspots identified at the interpentamer interfaces of TMEV were individually substituted to alanine to further explore their importance to the TMEV lifecycle. All the amino acid substitutions prevented completion of the virus lifecycle as no CPE was observed following transfection of susceptible cells. Immunofluorescence experiments demonstrated that virus protein synthesis and RNA replication were not inhibited by substitution of the hotspot residues, but that infectivity was severely impeded. This confirmed that the residues were required for some aspect of the virus lifecycle, such as capsid assembly, or were critical for maintaining the conformational stability of the TMEV particles. Virus capsids become unstable and are prone to dissociation under certain conditions such as extreme pH and non-physiological temperatures. The thermostability of TMEV was explored by selecting GDVII virions with improved thermal tolerance through serial passage and heat exposure. Thermostable virions that could tolerate temperatures above 57 °C had reduced infective titres compared to the wild type TMEV suggesting that the virus adapted to thermal stress at the expense of viral fitness. Sequencing the capsid encoding regions of the mutant virions revealed a pair of amino acid substitutions that were present in all mutants. Additional substitutions that were unique to viruses selected at different temperatures were also identified. Most of the substitutions were located within the intraprotomer interfaces of the virus, unlike previous studies on enteroviruses where mutations were mostly localised to the receptor binding pocket. This thesis provides the first analysis of the structural determinants of TMEV capsid stability. The generation of tools to further explore the capsid structures of TMEV and other picornaviruses provides an opportunity for future studies which may contribute to the development of novel control strategies against this important family of viruses. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text: false
- Date Issued: 2020
Exploring working with Grade 6 Elementary Agricultural Science teachers on how to integrate local knowledge in food preservation
- Authors: Sabina, Hashondili
- Date: 2020
- Subjects: Agriculture -- Study and teaching (Elementary) -- Namibia , Food -- Preservation -- Study and teaching (Elementary) -- Namibia , Education, Elementary -- Namibia , Ethnoscience -- Study and teaching (Elementary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/148093 , vital:38709
- Description: Many scholars have reported that science teachers are grappling with linking science to learners’ everyday life experiences and Namibian science teachers are no exception. As a result, learners are finding that scientific concepts often remain decontextualised and abstract. In light of this, the Namibian National Curriculum indicates that teaching and learning should start with the knowledge and experiences of learners from home. It also encourages teachers to integrate local knowledge into their science lessons but does not give proper guidelines on how science teachers should go about enacting this. This tension between curriculum formulation and implementation triggered my interest to carry out an interventionist research study aimed at exploring working with Grade 6 Elementary Agricultural Science teachers on how to integrate local knowledge on food preservation in particular. This study is underpinned by an interpretive paradigm, within which a qualitative case study was employed. It was conducted with three Grade 6 Elementary Agricultural Science teachers from three different schools in the Oshana region of Namibia. I used semi-structured interviews, document analysis, workshop discussions, participatory observation and reflections to gather data. Vygotsky’s socio-cultural theory together with Shulman’s pedagogical content knowledge theories was used as lenses to analyse my data. The findings of the study revealed that the sample teachers understood what indigenous knowledge is and its benefits but struggled to integrate it in their lessons. The findings of the study further revealed that the presentations by the expert community members enabled these teachers to identify possible science topics that they could teach, using some of the traditional practices such as food preservation. The study thus recommends that teachers need to be supported on how to integrate local knowledge or indigenous knowledge in their classrooms. Teachers should therefore be involved in professional learning communities that will help them share their difficulties they encounter during their teaching practices and to collaboratively come up with strategies to overcome such difficulties. Community members who are custodians of the cultural heritage should be invited to share their indigenous knowledge with science teachers so that they can link it from community members to classroom science.
- Full Text:
- Date Issued: 2020
- Authors: Sabina, Hashondili
- Date: 2020
- Subjects: Agriculture -- Study and teaching (Elementary) -- Namibia , Food -- Preservation -- Study and teaching (Elementary) -- Namibia , Education, Elementary -- Namibia , Ethnoscience -- Study and teaching (Elementary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/148093 , vital:38709
- Description: Many scholars have reported that science teachers are grappling with linking science to learners’ everyday life experiences and Namibian science teachers are no exception. As a result, learners are finding that scientific concepts often remain decontextualised and abstract. In light of this, the Namibian National Curriculum indicates that teaching and learning should start with the knowledge and experiences of learners from home. It also encourages teachers to integrate local knowledge into their science lessons but does not give proper guidelines on how science teachers should go about enacting this. This tension between curriculum formulation and implementation triggered my interest to carry out an interventionist research study aimed at exploring working with Grade 6 Elementary Agricultural Science teachers on how to integrate local knowledge on food preservation in particular. This study is underpinned by an interpretive paradigm, within which a qualitative case study was employed. It was conducted with three Grade 6 Elementary Agricultural Science teachers from three different schools in the Oshana region of Namibia. I used semi-structured interviews, document analysis, workshop discussions, participatory observation and reflections to gather data. Vygotsky’s socio-cultural theory together with Shulman’s pedagogical content knowledge theories was used as lenses to analyse my data. The findings of the study revealed that the sample teachers understood what indigenous knowledge is and its benefits but struggled to integrate it in their lessons. The findings of the study further revealed that the presentations by the expert community members enabled these teachers to identify possible science topics that they could teach, using some of the traditional practices such as food preservation. The study thus recommends that teachers need to be supported on how to integrate local knowledge or indigenous knowledge in their classrooms. Teachers should therefore be involved in professional learning communities that will help them share their difficulties they encounter during their teaching practices and to collaboratively come up with strategies to overcome such difficulties. Community members who are custodians of the cultural heritage should be invited to share their indigenous knowledge with science teachers so that they can link it from community members to classroom science.
- Full Text:
- Date Issued: 2020
F-and F+-band radioluminescence and the influence of annealing on its emission spectra in Al2O3: C, Mg:
- Chithambo, Makaiko L, Kalita, Jitumani M, Finch, A A
- Authors: Chithambo, Makaiko L , Kalita, Jitumani M , Finch, A A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150130 , vital:38942 , https://doi.org/10.1016/j.radmeas.2020.106306
- Description: Radioluminescence spectra of Al2O3:C,Mg monitored at temperatures up to 400 °C is reported. Measurements were made on samples either as received or on ones annealed at 1200 °C. Radioluminescence is observed at 410 nm for the unannealed sample but principally at 330 and 410 nm in the annealed sample with the emission at 330 nm dominant. Both bands are subject to thermal quenching but the change for the F+ band is atypical. Temperature induced effects on these and other bands are discussed, as are complementary measurements of thermoluminescence spectra.
- Full Text:
- Date Issued: 2020
- Authors: Chithambo, Makaiko L , Kalita, Jitumani M , Finch, A A
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/150130 , vital:38942 , https://doi.org/10.1016/j.radmeas.2020.106306
- Description: Radioluminescence spectra of Al2O3:C,Mg monitored at temperatures up to 400 °C is reported. Measurements were made on samples either as received or on ones annealed at 1200 °C. Radioluminescence is observed at 410 nm for the unannealed sample but principally at 330 and 410 nm in the annealed sample with the emission at 330 nm dominant. Both bands are subject to thermal quenching but the change for the F+ band is atypical. Temperature induced effects on these and other bands are discussed, as are complementary measurements of thermoluminescence spectra.
- Full Text:
- Date Issued: 2020
Fabrication of dye-sensitized solar cells based on push-pull asymmetrical substituted zinc and copper phthalocyanines and reduced graphene oxide nanosheet:
- Chindeka, Francis, Mashazi, Philani N, Britton, Jonathan, Oluwole, David O, Mapukata, Sivuyisiwe, Nyokong, Tebello
- Authors: Chindeka, Francis , Mashazi, Philani N , Britton, Jonathan , Oluwole, David O , Mapukata, Sivuyisiwe , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149076 , vital:38802 , https://doi.org/10.1016/j.jphotochem.2020.112612
- Description: Dye sensitized solar cells (DSSCs) were fabricated by using 2(3,5-biscarboxyphenoxy), 9(10), 16(17), 23(24)-tri(tertbutyl) phthalocyaninato Cu (4) and Zn (5) complexes as dyes on the ITO-TiO2 photoanodes containing reduced graphene oxide nanosheets (rGONS) or nitrogen-doped rGONS (NrGONS). The evaluation of the assembled DSSCs revealed that using ITO-TiO2-NrGONS-CuPc photoanode had the highest fill factor (FF) and power conversion efficiency (ɳ) of 69% and 4.36% respectively. These results show that the asymmetrical phthalocyanine complexes (4) and (5) exhibit significant improvement on the performance of the DSSC compared to our previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
- Full Text:
- Date Issued: 2020
- Authors: Chindeka, Francis , Mashazi, Philani N , Britton, Jonathan , Oluwole, David O , Mapukata, Sivuyisiwe , Nyokong, Tebello
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/149076 , vital:38802 , https://doi.org/10.1016/j.jphotochem.2020.112612
- Description: Dye sensitized solar cells (DSSCs) were fabricated by using 2(3,5-biscarboxyphenoxy), 9(10), 16(17), 23(24)-tri(tertbutyl) phthalocyaninato Cu (4) and Zn (5) complexes as dyes on the ITO-TiO2 photoanodes containing reduced graphene oxide nanosheets (rGONS) or nitrogen-doped rGONS (NrGONS). The evaluation of the assembled DSSCs revealed that using ITO-TiO2-NrGONS-CuPc photoanode had the highest fill factor (FF) and power conversion efficiency (ɳ) of 69% and 4.36% respectively. These results show that the asymmetrical phthalocyanine complexes (4) and (5) exhibit significant improvement on the performance of the DSSC compared to our previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
- Full Text:
- Date Issued: 2020
Fabrication of electrospun fibers from a porphyrin linked to polyacrylonitrile polymer for photocatalytic transformation of phenols
- Jones, Ben, Mafukidze, Donovan M, Nyokong, Tebello
- Authors: Jones, Ben , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186196 , vital:44472 , xlink:href="https://doi.org/10.1016/j.molstruc.2020.128191"
- Description: A novel mono-porphyrin (2) was employed for the photodegradation of 4-chlorophenol and 4-n-nonylphenol at pH 10.60. A partially modified polyacrylonitrile (PAN) polymer was utilized only as a support system for the photosensitiser to allow the formation of a covalent linkage. Complex 2 showed singlet oxygen values of 0.70 in dimethyl formamide and when conjugated (2-PAN) showed 0.39 in water. When employed against 4-chlorophenol a degradation efficiency (η) of 29.1% was achieved at 0.20 mol L−1 over a period of 10 min. When employed against 4-n-nonylphenol we obtained a η of 26.7% at 0.17 mol L−1 over a period of 10 min.
- Full Text:
- Date Issued: 2020
- Authors: Jones, Ben , Mafukidze, Donovan M , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186196 , vital:44472 , xlink:href="https://doi.org/10.1016/j.molstruc.2020.128191"
- Description: A novel mono-porphyrin (2) was employed for the photodegradation of 4-chlorophenol and 4-n-nonylphenol at pH 10.60. A partially modified polyacrylonitrile (PAN) polymer was utilized only as a support system for the photosensitiser to allow the formation of a covalent linkage. Complex 2 showed singlet oxygen values of 0.70 in dimethyl formamide and when conjugated (2-PAN) showed 0.39 in water. When employed against 4-chlorophenol a degradation efficiency (η) of 29.1% was achieved at 0.20 mol L−1 over a period of 10 min. When employed against 4-n-nonylphenol we obtained a η of 26.7% at 0.17 mol L−1 over a period of 10 min.
- Full Text:
- Date Issued: 2020
Falling towards the centre
- Authors: Maluleke, Vuyelwa
- Date: 2020
- Subjects: South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/142878 , vital:38125
- Description: I am interested in the poem as a textual body that is able to collect the ruptures, silences, music, and wounds of the body, Ukuzithutha, in order to perform their address. I seek to assemble these disfigured and fractured bodies, of which I am one, onto the page. And thus create an experimental, non-linear lyric of repetitions and fragmentations arranged into a memory text, to hold these stories against what Audre Lorde calls 'the tyranny of silence'. My thesis is influenced by Ntozake Shange's choreopoem, 'for colored girls who have considered suicide when the rainbow was enough', Claudia Rankine's 'Don't let me be Lonely', Sindiswa Bukusu's 'Loud and yellow laughter'. And Fiona Benson’s ‘Vertigo and Ghost’ whose form and lyric is a strong influence on the shape of the manuscript, and the construction of its mythologies.
- Full Text:
- Date Issued: 2020
- Authors: Maluleke, Vuyelwa
- Date: 2020
- Subjects: South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/142878 , vital:38125
- Description: I am interested in the poem as a textual body that is able to collect the ruptures, silences, music, and wounds of the body, Ukuzithutha, in order to perform their address. I seek to assemble these disfigured and fractured bodies, of which I am one, onto the page. And thus create an experimental, non-linear lyric of repetitions and fragmentations arranged into a memory text, to hold these stories against what Audre Lorde calls 'the tyranny of silence'. My thesis is influenced by Ntozake Shange's choreopoem, 'for colored girls who have considered suicide when the rainbow was enough', Claudia Rankine's 'Don't let me be Lonely', Sindiswa Bukusu's 'Loud and yellow laughter'. And Fiona Benson’s ‘Vertigo and Ghost’ whose form and lyric is a strong influence on the shape of the manuscript, and the construction of its mythologies.
- Full Text:
- Date Issued: 2020
Fertility, childbirth and parenting Defining sexual and gender relations
- Macleod, Catriona I, Morison, Tracy
- Authors: Macleod, Catriona I , Morison, Tracy
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/434112 , vital:73032 , ISBN 9781108460903 , https://biblio.co.uk/book/cambridge-handbook-international-psychology-women-fan-ny/d/1521282285?aid=frggad_source=1gclid=CjwKCAjwz42xBhB9EiwA48pT70yXdV4oAp4StC49UDVfIuCISAVjZGdeibEiPkf_CNtGgog6bJ7iDxoCgSIQAvD_BwE
- Description: Major historical shifts in the field of fertility, childbirth and parenting have implications for feminist psychologists working on these topics. These shifts include approaches to sexuality and reproduction: a population control emphasis in the late 1940s, a reproductive rights paradigm in the 1990s, and progression from reproductive rights to reproductive justice. Feminist psychologists must traverse the political landscape created by these broad approaches. In this chapter, we suggest ways in which such engagement may be facilitated through examination of mainstream assumptions and outcomes and the use of nuanced feminist research. Drawing from transnational feminisms, the principles of reproductive justice, and examples of research and interventions in reproductive decisionmaking, abortion, obstetric violence, ‘deviant’ (m)others, early reproduction and contraception, we argue that feminist psychology should attend to both global and crosscutting power relations concerning fertility and reproduction, as well as localised dynamics.
- Full Text:
- Date Issued: 2020
- Authors: Macleod, Catriona I , Morison, Tracy
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/434112 , vital:73032 , ISBN 9781108460903 , https://biblio.co.uk/book/cambridge-handbook-international-psychology-women-fan-ny/d/1521282285?aid=frggad_source=1gclid=CjwKCAjwz42xBhB9EiwA48pT70yXdV4oAp4StC49UDVfIuCISAVjZGdeibEiPkf_CNtGgog6bJ7iDxoCgSIQAvD_BwE
- Description: Major historical shifts in the field of fertility, childbirth and parenting have implications for feminist psychologists working on these topics. These shifts include approaches to sexuality and reproduction: a population control emphasis in the late 1940s, a reproductive rights paradigm in the 1990s, and progression from reproductive rights to reproductive justice. Feminist psychologists must traverse the political landscape created by these broad approaches. In this chapter, we suggest ways in which such engagement may be facilitated through examination of mainstream assumptions and outcomes and the use of nuanced feminist research. Drawing from transnational feminisms, the principles of reproductive justice, and examples of research and interventions in reproductive decisionmaking, abortion, obstetric violence, ‘deviant’ (m)others, early reproduction and contraception, we argue that feminist psychology should attend to both global and crosscutting power relations concerning fertility and reproduction, as well as localised dynamics.
- Full Text:
- Date Issued: 2020
Finite precision arithmetic in Polyphase Filterbank implementations
- Authors: Myburgh, Talon
- Date: 2020
- Subjects: Radio interferometers , Interferometry , Radio telescopes , Gate array circuits , Floating-point arithmetic , Python (Computer program language) , Polyphase Filterbank , Finite precision arithmetic , MeerKAT
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146187 , vital:38503
- Description: The MeerKAT is the most sensitive radio telescope in its class, and it is important that systematic effects do not limit the dynamic range of the instrument, preventing this sensitivity from being harnessed for deep integrations. During commissioning, spurious artefacts were noted in the MeerKAT passband and the root cause was attributed to systematic errors in the digital signal path. Finite precision arithmetic used by the Polyphase Filterbank (PFB) was one of the main factors contributing to the spurious responses, together with bugs in the firmware. This thesis describes a software PFB simulator that was built to mimic the MeerKAT PFB and allow investigation into the origin and mitigation of the effects seen on the telescope. This simulator was used to investigate the effects in signal integrity of various rounding techniques, overflow strategies and dual polarisation processing in the PFB. Using the simulator to investigate a number of different signal levels, bit-width and algorithmic scenarios, it gave insight into how the periodic dips occurring in the MeerKAT passband were the result of the implementation using an inappropriate rounding strategy. It further indicated how to select the best strategy for preventing overflow while maintaining high quantization effciency in the FFT. This practice of simulating the design behaviour in the PFB independently of the tools used to design the DSP firmware, is a step towards an end-to-end simulation of the MeerKAT system (or any radio telescope using nite precision digital signal processing systems). This would be useful for design, diagnostics, signal analysis and prototyping of the overall instrument.
- Full Text:
- Date Issued: 2020
- Authors: Myburgh, Talon
- Date: 2020
- Subjects: Radio interferometers , Interferometry , Radio telescopes , Gate array circuits , Floating-point arithmetic , Python (Computer program language) , Polyphase Filterbank , Finite precision arithmetic , MeerKAT
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146187 , vital:38503
- Description: The MeerKAT is the most sensitive radio telescope in its class, and it is important that systematic effects do not limit the dynamic range of the instrument, preventing this sensitivity from being harnessed for deep integrations. During commissioning, spurious artefacts were noted in the MeerKAT passband and the root cause was attributed to systematic errors in the digital signal path. Finite precision arithmetic used by the Polyphase Filterbank (PFB) was one of the main factors contributing to the spurious responses, together with bugs in the firmware. This thesis describes a software PFB simulator that was built to mimic the MeerKAT PFB and allow investigation into the origin and mitigation of the effects seen on the telescope. This simulator was used to investigate the effects in signal integrity of various rounding techniques, overflow strategies and dual polarisation processing in the PFB. Using the simulator to investigate a number of different signal levels, bit-width and algorithmic scenarios, it gave insight into how the periodic dips occurring in the MeerKAT passband were the result of the implementation using an inappropriate rounding strategy. It further indicated how to select the best strategy for preventing overflow while maintaining high quantization effciency in the FFT. This practice of simulating the design behaviour in the PFB independently of the tools used to design the DSP firmware, is a step towards an end-to-end simulation of the MeerKAT system (or any radio telescope using nite precision digital signal processing systems). This would be useful for design, diagnostics, signal analysis and prototyping of the overall instrument.
- Full Text:
- Date Issued: 2020
First candidates for γ vibrational bands built on the [505] 11/2− neutron orbital in odd-A Dy isotopes:
- Majola, S N T, Sithole, M A, Mdletshe, L, Hartley, D, Timár, J, Nyakó, B M, Allmond, J M, Bark, R A, Beausang, C, Bianco, L, Bucher, T D, Bvumbi, S P, Carpenter, M P, Chiara, C J, Cooper, N, Cullen, D M, Curien, D, Dinoko, T S, Gall, B J P, Garrett, P E, Greenlees, P T, Hirvonen, J, Jakobsson, U, Jones, P M, Julin, R, Juutinen, S, Ketelhut, S, Keswa, B V, Kondev, F G, Korichi, A, Kulp, W D, Lauritsen, T, Lawrie, E A, Makhathini, L, Masiteng, P L, Maqabuka, B, McCutchan, E A, Miller, D, Miller, S, Minkova, A, Msebi, L, Mthembu, S H, Ndayishmiye, J, Nieminen, P, Ngcobo, P Z, Ntshamgase, S S, Orce, J N, Peura, P, Rahkila, P, Redon, N, Riedinger, L L, Riley, M A, Roux, D G, Ruotsalainen, P, Piot, J, Saren, J, Sharpey-Schafer, J F, Scholey, C, Shirinda, O, Simpson, J, Sorri, J, Stefansecu, I, Stolze, S, Uusitalo, J, Wang, X, Werner, V, Wood, J L, Yu, C-H, Zhu, S, Zimba, G
- Authors: Majola, S N T , Sithole, M A , Mdletshe, L , Hartley, D , Timár, J , Nyakó, B M , Allmond, J M , Bark, R A , Beausang, C , Bianco, L , Bucher, T D , Bvumbi, S P , Carpenter, M P , Chiara, C J , Cooper, N , Cullen, D M , Curien, D , Dinoko, T S , Gall, B J P , Garrett, P E , Greenlees, P T , Hirvonen, J , Jakobsson, U , Jones, P M , Julin, R , Juutinen, S , Ketelhut, S , Keswa, B V , Kondev, F G , Korichi, A , Kulp, W D , Lauritsen, T , Lawrie, E A , Makhathini, L , Masiteng, P L , Maqabuka, B , McCutchan, E A , Miller, D , Miller, S , Minkova, A , Msebi, L , Mthembu, S H , Ndayishmiye, J , Nieminen, P , Ngcobo, P Z , Ntshamgase, S S , Orce, J N , Peura, P , Rahkila, P , Redon, N , Riedinger, L L , Riley, M A , Roux, D G , Ruotsalainen, P , Piot, J , Saren, J , Sharpey-Schafer, J F , Scholey, C , Shirinda, O , Simpson, J , Sorri, J , Stefansecu, I , Stolze, S , Uusitalo, J , Wang, X , Werner, V , Wood, J L , Yu, C-H , Zhu, S , Zimba, G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148827 , vital:38777 , https://0-journals.aps.org.wam.seals.ac.za/prc/abstract/10.1103/PhysRevC.101.044312
- Description: Rotational structures have been measured using the Jurogam II and GAMMASPHERE arrays at low spin following the 155Gd(α,2n)157Dy and 148Nd(12C,5n)155Dy reactions at 25 and 65 MeV, respectively. We report high-K bands, which are conjectured to be the first candidates of a Kπ=2+γ vibrational band, built on the [505]11/2− neutron orbital, in both odd-A155,157Dy isotopes. The coupling of the first excited K=0+ states or the so-called β vibrational bands at 661 and 676 keV in 154Dy and 156Dy to the [505]11/2− orbital, to produce a Kπ=11/2− band, was not observed in both 155Dy and 157Dy, respectively. The implication of these findings on the interpretation of the first excited 0+ states in the core nuclei 154Dy and 156Dy are also discussed.
- Full Text:
- Date Issued: 2020
- Authors: Majola, S N T , Sithole, M A , Mdletshe, L , Hartley, D , Timár, J , Nyakó, B M , Allmond, J M , Bark, R A , Beausang, C , Bianco, L , Bucher, T D , Bvumbi, S P , Carpenter, M P , Chiara, C J , Cooper, N , Cullen, D M , Curien, D , Dinoko, T S , Gall, B J P , Garrett, P E , Greenlees, P T , Hirvonen, J , Jakobsson, U , Jones, P M , Julin, R , Juutinen, S , Ketelhut, S , Keswa, B V , Kondev, F G , Korichi, A , Kulp, W D , Lauritsen, T , Lawrie, E A , Makhathini, L , Masiteng, P L , Maqabuka, B , McCutchan, E A , Miller, D , Miller, S , Minkova, A , Msebi, L , Mthembu, S H , Ndayishmiye, J , Nieminen, P , Ngcobo, P Z , Ntshamgase, S S , Orce, J N , Peura, P , Rahkila, P , Redon, N , Riedinger, L L , Riley, M A , Roux, D G , Ruotsalainen, P , Piot, J , Saren, J , Sharpey-Schafer, J F , Scholey, C , Shirinda, O , Simpson, J , Sorri, J , Stefansecu, I , Stolze, S , Uusitalo, J , Wang, X , Werner, V , Wood, J L , Yu, C-H , Zhu, S , Zimba, G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148827 , vital:38777 , https://0-journals.aps.org.wam.seals.ac.za/prc/abstract/10.1103/PhysRevC.101.044312
- Description: Rotational structures have been measured using the Jurogam II and GAMMASPHERE arrays at low spin following the 155Gd(α,2n)157Dy and 148Nd(12C,5n)155Dy reactions at 25 and 65 MeV, respectively. We report high-K bands, which are conjectured to be the first candidates of a Kπ=2+γ vibrational band, built on the [505]11/2− neutron orbital, in both odd-A155,157Dy isotopes. The coupling of the first excited K=0+ states or the so-called β vibrational bands at 661 and 676 keV in 154Dy and 156Dy to the [505]11/2− orbital, to produce a Kπ=11/2− band, was not observed in both 155Dy and 157Dy, respectively. The implication of these findings on the interpretation of the first excited 0+ states in the core nuclei 154Dy and 156Dy are also discussed.
- Full Text:
- Date Issued: 2020