Exploring domestic workers’ subjectivities through stories of their personal childcare arrangements
- Authors: Michaeu, Nisha
- Date: 2021
- Subjects: Women household employees, Black -- Social conditions -- South Africa , Women household employees, Black -- Social conditions -- South Africa -- Case studies , Women household employees, Black -- Psychology -- South Africa , Day care aides -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/172029 , vital:42150
- Description: Domestic service has long been a major sector of the South African labour market, for black women particularly, who must support their family and children. Existing research has stressed the way in which race, class and gender has shaped the oppressive character of domestic service in South Africa. In this narrative study a new slant is provided on this existing theoretical discussion of domestic labour, one that is focused on exploring the agentic human being beyond ‘the servant question’. This study uses narrative interviews with domestic workers in Makhanda/Grahamstown in the Eastern Cape province of South Africa to show how we can expand on potentially limited or constricted passive ‘domestic worker identities’ and ideas/beliefs about women who do domestic work. A performative and positioning narrative analysis is used to explore the subject positions of domestic workers in their stories about their childcare arrangements. This analysis examines multiple shifting identities and positions that are used by domestic workers in relation to their maternal subjectivity and their audience (here, a white trainee-psychologist esearcher), while highlighting the significance of narrative methodology in making these positions visible. The areas of focus were their history, experience of domestic work, life outside of domestic work, family network/dynamics and personal childcare arrangements. Under these areas of focus the following was analysed: the ways in which the storyteller positioned herself in her narrative, how she compared/contrasted or located herself in relation to the other, claims of identity that were made, what she incorporated or purposefully left out, words and phrases that were chosen, which sections of talk were embellished or elaborated on and appeals that were made to the interviewer (Riessman, 2002). Through exploring the micro-practices of domestic workers’ lives the study found that there were various subject positions constructed and used by this group of women. Findings showed that domestic workers positioned themselves actively as breadwinners, good mothers who give their children opportunities that they were not given, nurturers and crafty mothers who secure good care for their children. In contrast to these active subject positions, positions of sacrifice were performed when domestic workers spoke about leaving their young children in the care of another while they worked. The study also found that participants managed complex positions of disappointment and unmet expectations for a better life in the new South Africa by using narratives of resistance and agency. In certain instances, identity appeals were made to the interviewer that they, and other women who do domestic work, are entrepreneurial and creative with their income and possess skills outside of their day-to-day household cleaning jobs. This was interpreted as an attempt to extend the domestic worker identity positioning beyond the traditionally accepted notions of unskilled/uneducated women who do domestic work. In the study this allowed for more subject positions to be taken up in terms of identities and selves, beyond just being a “domestic worker”.
- Full Text:
- Date Issued: 2021
- Authors: Michaeu, Nisha
- Date: 2021
- Subjects: Women household employees, Black -- Social conditions -- South Africa , Women household employees, Black -- Social conditions -- South Africa -- Case studies , Women household employees, Black -- Psychology -- South Africa , Day care aides -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/172029 , vital:42150
- Description: Domestic service has long been a major sector of the South African labour market, for black women particularly, who must support their family and children. Existing research has stressed the way in which race, class and gender has shaped the oppressive character of domestic service in South Africa. In this narrative study a new slant is provided on this existing theoretical discussion of domestic labour, one that is focused on exploring the agentic human being beyond ‘the servant question’. This study uses narrative interviews with domestic workers in Makhanda/Grahamstown in the Eastern Cape province of South Africa to show how we can expand on potentially limited or constricted passive ‘domestic worker identities’ and ideas/beliefs about women who do domestic work. A performative and positioning narrative analysis is used to explore the subject positions of domestic workers in their stories about their childcare arrangements. This analysis examines multiple shifting identities and positions that are used by domestic workers in relation to their maternal subjectivity and their audience (here, a white trainee-psychologist esearcher), while highlighting the significance of narrative methodology in making these positions visible. The areas of focus were their history, experience of domestic work, life outside of domestic work, family network/dynamics and personal childcare arrangements. Under these areas of focus the following was analysed: the ways in which the storyteller positioned herself in her narrative, how she compared/contrasted or located herself in relation to the other, claims of identity that were made, what she incorporated or purposefully left out, words and phrases that were chosen, which sections of talk were embellished or elaborated on and appeals that were made to the interviewer (Riessman, 2002). Through exploring the micro-practices of domestic workers’ lives the study found that there were various subject positions constructed and used by this group of women. Findings showed that domestic workers positioned themselves actively as breadwinners, good mothers who give their children opportunities that they were not given, nurturers and crafty mothers who secure good care for their children. In contrast to these active subject positions, positions of sacrifice were performed when domestic workers spoke about leaving their young children in the care of another while they worked. The study also found that participants managed complex positions of disappointment and unmet expectations for a better life in the new South Africa by using narratives of resistance and agency. In certain instances, identity appeals were made to the interviewer that they, and other women who do domestic work, are entrepreneurial and creative with their income and possess skills outside of their day-to-day household cleaning jobs. This was interpreted as an attempt to extend the domestic worker identity positioning beyond the traditionally accepted notions of unskilled/uneducated women who do domestic work. In the study this allowed for more subject positions to be taken up in terms of identities and selves, beyond just being a “domestic worker”.
- Full Text:
- Date Issued: 2021
Exploring the role of supervisors in developing employee commitment in a Namibian Public Institution from the subordinates’ perspective
- Authors: Daniel, Anna
- Date: 2021
- Subjects: Supervisors -- Namibia -- Case studies , Leadership -- Namibia -- Case studies , Employee motivation -- Namibia -- Case studies , Employee loyalty -- Namibia -- Case studies , Supervision -- Namibia -- Case studies , Management -- Employee participation -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/170770 , vital:41958
- Description: Over the years, scholars have noted the importance of organisations managing the performance of their employees by effectively maintaining their commitment. Hence, l ite rature highlighted that employee s have the potential to be recognised as a source of competitive advantage for an organisation and not a resource of an organisation. The main aim of the study was to explore the role of supervisors in developing employee commitment in a Namibian Public Ins titution from the subordinates’ perspective. The focus of this research was to understand how subordinates were included in decision making and were supported by their supervisors , and on how subordinates received feed b ack on role fulfilment and performance from their supervisors. Furthermore, the study described how subordinates viewed the leadership behaviour of their supervisors and how this i nfluenced employee commitment. The data was collected using qualitative me t hods through semi - structured face - to - face interview s with the subordinates of the selected institution. During this study, a sample of 15 subordinates taken from a population of 266 within the institution’s structure was inte rviewed . The interview quest ion s were based on how supervisors included subordinates in decision making, developed subordinates ’ support and delivered feedback on role and performance. The study used secondary data to determine the level of performance against set targets of the inst itu tion, using the annual performance report of the institution. In addition , the study used the staff access control syste m to determine the work time s of employees Lastly, the study analysed the data regarding staff resignation for the last five years to a ssess the level of staff turnover rate of the institution. The study f ound that the subordinates felt the re should be greater subordinate inclusion in decision making, increased levels of re gular feedback and higher levels of support shown by supervis ors t o subordinates when e xecuting their jobs. The study further highlighted the importance of supervisors to develop the ability of shifting from one leadership style to another depending on the situation at hand. The study reviewed six leadership style s that could influence commitment . Therefore, the study recommend s th at the institution direct its attention towards developing the situational leadership skills of their supervisors and developing their skills to enable them to better harmonise teamwork, increas e regular communication and give regular feedback to their subordinates . The results from this research will be beneficial to public institutions within the region and will, in add ition, enhance the academic body of literature in this field . The s tudy will draw the attention of supervisors to the importance of their behaviour, conduct, and their subsequent impact on employee commitment.
- Full Text:
- Date Issued: 2021
- Authors: Daniel, Anna
- Date: 2021
- Subjects: Supervisors -- Namibia -- Case studies , Leadership -- Namibia -- Case studies , Employee motivation -- Namibia -- Case studies , Employee loyalty -- Namibia -- Case studies , Supervision -- Namibia -- Case studies , Management -- Employee participation -- Namibia -- Case studies
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/170770 , vital:41958
- Description: Over the years, scholars have noted the importance of organisations managing the performance of their employees by effectively maintaining their commitment. Hence, l ite rature highlighted that employee s have the potential to be recognised as a source of competitive advantage for an organisation and not a resource of an organisation. The main aim of the study was to explore the role of supervisors in developing employee commitment in a Namibian Public Ins titution from the subordinates’ perspective. The focus of this research was to understand how subordinates were included in decision making and were supported by their supervisors , and on how subordinates received feed b ack on role fulfilment and performance from their supervisors. Furthermore, the study described how subordinates viewed the leadership behaviour of their supervisors and how this i nfluenced employee commitment. The data was collected using qualitative me t hods through semi - structured face - to - face interview s with the subordinates of the selected institution. During this study, a sample of 15 subordinates taken from a population of 266 within the institution’s structure was inte rviewed . The interview quest ion s were based on how supervisors included subordinates in decision making, developed subordinates ’ support and delivered feedback on role and performance. The study used secondary data to determine the level of performance against set targets of the inst itu tion, using the annual performance report of the institution. In addition , the study used the staff access control syste m to determine the work time s of employees Lastly, the study analysed the data regarding staff resignation for the last five years to a ssess the level of staff turnover rate of the institution. The study f ound that the subordinates felt the re should be greater subordinate inclusion in decision making, increased levels of re gular feedback and higher levels of support shown by supervis ors t o subordinates when e xecuting their jobs. The study further highlighted the importance of supervisors to develop the ability of shifting from one leadership style to another depending on the situation at hand. The study reviewed six leadership style s that could influence commitment . Therefore, the study recommend s th at the institution direct its attention towards developing the situational leadership skills of their supervisors and developing their skills to enable them to better harmonise teamwork, increas e regular communication and give regular feedback to their subordinates . The results from this research will be beneficial to public institutions within the region and will, in add ition, enhance the academic body of literature in this field . The s tudy will draw the attention of supervisors to the importance of their behaviour, conduct, and their subsequent impact on employee commitment.
- Full Text:
- Date Issued: 2021
External Factors affecting Blackboard Learning Management System adoption by Students: Evidence from a Historically Disadvantaged Higher Education Institution in South Africa
- O. Matarirano, M. Panicker, N.R. Jere https://orcid.org/0000-0001-8966-2753, A. Maliwa
- Authors: O. Matarirano , M. Panicker , N.R. Jere https://orcid.org/0000-0001-8966-2753 , A. Maliwa
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3304 , vital:43306 , https://doi.org/10.20853/35-2-4025
- Description: Learning Management Systems (LMS) have the ability to transform learning experiences of students in Higher Education Institutions (HEI). In addition to the developmental benefits, LMS assist teaching and learning during student unrests, a common feature in historically disadvantaged institutions in South Africa. Regardless of the benefits of LMS platforms such as Blackboard, the utilisation by university students at the institution under study has been very low. Applying cross sectional electronic survey, this study identifies the key factors influencing technology adoption, as identified in the General Extended Technology Acceptance Model for E-Learning (GETAMEL), behind perceived ease of use and perceived usefulness in the adoption of technology. A sample of 125 students at a historically disadvantaged institution in South Africa was considered for the study. Data was collected to understand their perceptions on use of Blackboard Learning Management System (BB) for learning. Data was analysed with SmartPLS statistical analysis software. Results show that perceived ease of use of BB is influenced by computer self-efficacy, computer amusement and computer anxiety whilst perceived usefulness of BB is influenced by subjective norm and computer enjoyment. The findings also show computer experience to significantly affect computer self-efficacy and computer self-efficacy to affect computer enjoyment. The article presents the external factors that affect the usage of LMS at one of the historically disadvantaged HEI in South Africa. HEI leadership has to prioritise the identified external factors to increase chances of acceptance and utilisation of Blackboard by learners.
- Full Text:
- Date Issued: 2021
- Authors: O. Matarirano , M. Panicker , N.R. Jere https://orcid.org/0000-0001-8966-2753 , A. Maliwa
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/3304 , vital:43306 , https://doi.org/10.20853/35-2-4025
- Description: Learning Management Systems (LMS) have the ability to transform learning experiences of students in Higher Education Institutions (HEI). In addition to the developmental benefits, LMS assist teaching and learning during student unrests, a common feature in historically disadvantaged institutions in South Africa. Regardless of the benefits of LMS platforms such as Blackboard, the utilisation by university students at the institution under study has been very low. Applying cross sectional electronic survey, this study identifies the key factors influencing technology adoption, as identified in the General Extended Technology Acceptance Model for E-Learning (GETAMEL), behind perceived ease of use and perceived usefulness in the adoption of technology. A sample of 125 students at a historically disadvantaged institution in South Africa was considered for the study. Data was collected to understand their perceptions on use of Blackboard Learning Management System (BB) for learning. Data was analysed with SmartPLS statistical analysis software. Results show that perceived ease of use of BB is influenced by computer self-efficacy, computer amusement and computer anxiety whilst perceived usefulness of BB is influenced by subjective norm and computer enjoyment. The findings also show computer experience to significantly affect computer self-efficacy and computer self-efficacy to affect computer enjoyment. The article presents the external factors that affect the usage of LMS at one of the historically disadvantaged HEI in South Africa. HEI leadership has to prioritise the identified external factors to increase chances of acceptance and utilisation of Blackboard by learners.
- Full Text:
- Date Issued: 2021
Farm notes
- Authors: Berold, Robert
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , poem
- Identifier: http://hdl.handle.net/10962/468683 , vital:77113 , ISBN 0028-4459 , https://journals.co.za/doi/epdf/10.10520/ejc-iseacoin_v57_n2_a6
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 2021
- Authors: Berold, Robert
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , poem
- Identifier: http://hdl.handle.net/10962/468683 , vital:77113 , ISBN 0028-4459 , https://journals.co.za/doi/epdf/10.10520/ejc-iseacoin_v57_n2_a6
- Description: New Coin is one of South Africa's most established and influential poetry journals. It publishes poetry, and poetry-related reviews, commentary and interviews. New Coin places a particular emphasis on evolving forms and experimental use of the English language in poetry in the South African context. In this sense it has traced the most exciting trends and currents in contemporary poetry in South Africa for a decade of more. The journal is published twice a year in June and December by the Institute for the Study of English in Africa (ISEA), Rhodes University.
- Full Text:
- Date Issued: 2021
Feasibility Study: Computing Confidence Interval (CI) for IBR Data Using Bootstrapping Technique
- Chindipha, Stones D, Irwin, Barry V W
- Authors: Chindipha, Stones D , Irwin, Barry V W
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427665 , vital:72454 , https://www.researchgate.net/profile/Barry-Ir-win/publication/358895311_Feasibility_Study_Computing_Confidence_Inter-val_CI_for_IBR_Data_Using_Bootstrapping_Technique/links/621bdc469947d339eb6e578b/Feasibility-Study-Computing-Confidence-Interval-CI-for-IBR-Data-Using-Bootstrapping-Technique.pdf
- Description: Statistical bootstrapping has been used in different fields over the years since it was introduced as a technique that one can use to simulate data. In this study, parametric and nonparametric bootstrapping techniques were used to create samples of different compositions from the baseline data. The bootstrap distribution of a point estimator of a population parameter has been used in the past to produce a bootstrapped confidence interval (CI) for the parameter’s true value, if the parameter is written as a function of the population’s distribution. Population parameters are estimated with many point estimators. The study used mean as the population parameter of interest from which bootstrap samples were created. This research was more interested in the CI side of bootstrapping and it is this aspect that this paper focused on. This is the case because the study wanted to offer a certain degree of assurance and reliability of IBR data to users who may not have access to a larger ’lens’ of a network telescope to allow them to monitor security threats in their network. The primary interest in the dataset were source and destination IP (DSTIP) addresses, thus the study selected different size pools of DSTIP addresses to simulate bootstrap samples.
- Full Text:
- Date Issued: 2021
- Authors: Chindipha, Stones D , Irwin, Barry V W
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/427665 , vital:72454 , https://www.researchgate.net/profile/Barry-Ir-win/publication/358895311_Feasibility_Study_Computing_Confidence_Inter-val_CI_for_IBR_Data_Using_Bootstrapping_Technique/links/621bdc469947d339eb6e578b/Feasibility-Study-Computing-Confidence-Interval-CI-for-IBR-Data-Using-Bootstrapping-Technique.pdf
- Description: Statistical bootstrapping has been used in different fields over the years since it was introduced as a technique that one can use to simulate data. In this study, parametric and nonparametric bootstrapping techniques were used to create samples of different compositions from the baseline data. The bootstrap distribution of a point estimator of a population parameter has been used in the past to produce a bootstrapped confidence interval (CI) for the parameter’s true value, if the parameter is written as a function of the population’s distribution. Population parameters are estimated with many point estimators. The study used mean as the population parameter of interest from which bootstrap samples were created. This research was more interested in the CI side of bootstrapping and it is this aspect that this paper focused on. This is the case because the study wanted to offer a certain degree of assurance and reliability of IBR data to users who may not have access to a larger ’lens’ of a network telescope to allow them to monitor security threats in their network. The primary interest in the dataset were source and destination IP (DSTIP) addresses, thus the study selected different size pools of DSTIP addresses to simulate bootstrap samples.
- Full Text:
- Date Issued: 2021
Field-based ecological studies to assess prospective biological control agents for invasive alien plants: An example from giant rat's tail grass
- Sutton, Guy F, Canavan, Kim N, Day, Michael M, Paterson, Iain D
- Authors: Sutton, Guy F , Canavan, Kim N , Day, Michael M , Paterson, Iain D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423756 , vital:72091 , xlink:href="https://doi.org/10.1111/1365-2664.13834"
- Description: Biological control (biocontrol) of invasive alien plants is a widely utilised weed management tool. Prospective biocontrol agents are typically assessed through host specificity testing and pre-release efficacy studies performed in quarantine. However, rearing of the potential biocontrol agents and/or test plants is often difficult or impossible under quarantine conditions. Moreover, practitioners may attain laboratory artefacts in quarantine, which may result in the potential agent being needlessly rejected. Field-based studies in the weed's indigenous distribution could overcome these issues.
- Full Text:
- Date Issued: 2021
- Authors: Sutton, Guy F , Canavan, Kim N , Day, Michael M , Paterson, Iain D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423756 , vital:72091 , xlink:href="https://doi.org/10.1111/1365-2664.13834"
- Description: Biological control (biocontrol) of invasive alien plants is a widely utilised weed management tool. Prospective biocontrol agents are typically assessed through host specificity testing and pre-release efficacy studies performed in quarantine. However, rearing of the potential biocontrol agents and/or test plants is often difficult or impossible under quarantine conditions. Moreover, practitioners may attain laboratory artefacts in quarantine, which may result in the potential agent being needlessly rejected. Field-based studies in the weed's indigenous distribution could overcome these issues.
- Full Text:
- Date Issued: 2021
Flavonoids from the Genus Euphorbia
- Magozwi, Douglas K, Dinala, Mmabatho, Mokwana, Nthabiseng, Siwe-Noundou, Xavier, Krause, Rui W M, Sonopo, Molahleli, McGaw, Lyndy J, Augustyn, Wilma A, Tembu, Vuyelwa J
- Authors: Magozwi, Douglas K , Dinala, Mmabatho , Mokwana, Nthabiseng , Siwe-Noundou, Xavier , Krause, Rui W M , Sonopo, Molahleli , McGaw, Lyndy J , Augustyn, Wilma A , Tembu, Vuyelwa J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191736 , vital:45159 , xlink:href="https://doi.org/10.3390/ph14050428"
- Description: Plants of the genus Euphorbia are widely distributed across temperate, tropical and subtropical regions of South America, Asia and Africa with established Ayurvedic, Chinese and Malay ethnomedical records. The present review reports the isolation, occurrence, phytochemistry, biological properties, therapeutic potential and structure–activity relationship of Euphorbia flavonoids for the period covering 2000–2020, while identifying potential areas for future studies aimed at development of new therapeutic agents from these plants. The findings suggest that the extracts and isolated flavonoids possess anticancer, antiproliferative, antimalarial, antibacterial, anti-venom, anti-inflammatory, anti-hepatitis and antioxidant properties and have different mechanisms of action against cancer cells. Of the investigated species, over 80 different types of flavonoids have been isolated to date. Most of the isolated flavonoids were flavonols and comprised simple O-substitution patterns, C-methylation and prenylation. Others had a glycoside, glycosidic linkages and a carbohydrate attached at either C-3 or C-7, and were designated as d-glucose, l-rhamnose or glucorhamnose. The structure–activity relationship studies showed that methylation of the hydroxyl groups on C-3 or C-7 reduces the activities while glycosylation loses the activity and that the parent skeletal structure is essential in retaining the activity. These constituents can therefore offer potential alternative scaffolds towards development of new Euphorbia-based therapeutic agents.
- Full Text:
- Date Issued: 2021
- Authors: Magozwi, Douglas K , Dinala, Mmabatho , Mokwana, Nthabiseng , Siwe-Noundou, Xavier , Krause, Rui W M , Sonopo, Molahleli , McGaw, Lyndy J , Augustyn, Wilma A , Tembu, Vuyelwa J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/191736 , vital:45159 , xlink:href="https://doi.org/10.3390/ph14050428"
- Description: Plants of the genus Euphorbia are widely distributed across temperate, tropical and subtropical regions of South America, Asia and Africa with established Ayurvedic, Chinese and Malay ethnomedical records. The present review reports the isolation, occurrence, phytochemistry, biological properties, therapeutic potential and structure–activity relationship of Euphorbia flavonoids for the period covering 2000–2020, while identifying potential areas for future studies aimed at development of new therapeutic agents from these plants. The findings suggest that the extracts and isolated flavonoids possess anticancer, antiproliferative, antimalarial, antibacterial, anti-venom, anti-inflammatory, anti-hepatitis and antioxidant properties and have different mechanisms of action against cancer cells. Of the investigated species, over 80 different types of flavonoids have been isolated to date. Most of the isolated flavonoids were flavonols and comprised simple O-substitution patterns, C-methylation and prenylation. Others had a glycoside, glycosidic linkages and a carbohydrate attached at either C-3 or C-7, and were designated as d-glucose, l-rhamnose or glucorhamnose. The structure–activity relationship studies showed that methylation of the hydroxyl groups on C-3 or C-7 reduces the activities while glycosylation loses the activity and that the parent skeletal structure is essential in retaining the activity. These constituents can therefore offer potential alternative scaffolds towards development of new Euphorbia-based therapeutic agents.
- Full Text:
- Date Issued: 2021
Folic acid-modified phthalocyanine-nanozyme loaded liposomes for targeted photodynamic therapy
- Nwahara, Nnamdi, Abrahams, Garth, Prinsloo, Earl, Nyokong, Tebello
- Authors: Nwahara, Nnamdi , Abrahams, Garth , Prinsloo, Earl , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231369 , vital:49881 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102527"
- Description: The hypoxic tumour microenvironment and poor spatiotemporal localization of photosensitizers are two significant obstacles that limit practical applications of photodynamic therapy. In response, a biocompatible, light-activatable liposome integrated with both a zinc phthalocyanine photodynamic component and Pt nanoparticles-decorated with MnO2 catalase-mimicking component are engineered. This multifunctional system was rationally designed using unsaturated phospholipids to achieve on-demand drug release following light irradiation. Specificity was achieved by folic acid functionalization resulting in folate-modified liposomes (FTLiposomes). We demonstrated its specific uptake by fluorescence imaging using folate receptor (FR) overexpressing HeLa and MCF-7 cells as in vitro models. This multifunctional liposome exhibits superior hypoxic anti-tumour effects and holds the potential to reduce side effects associated with untargeted therapy. Fluorescence of the constituent ZnPc and folate-receptor targeting could enable tracking and permit spatiotemporal regulation for improved cancer treatment.
- Full Text:
- Date Issued: 2021
- Authors: Nwahara, Nnamdi , Abrahams, Garth , Prinsloo, Earl , Nyokong, Tebello
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/231369 , vital:49881 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102527"
- Description: The hypoxic tumour microenvironment and poor spatiotemporal localization of photosensitizers are two significant obstacles that limit practical applications of photodynamic therapy. In response, a biocompatible, light-activatable liposome integrated with both a zinc phthalocyanine photodynamic component and Pt nanoparticles-decorated with MnO2 catalase-mimicking component are engineered. This multifunctional system was rationally designed using unsaturated phospholipids to achieve on-demand drug release following light irradiation. Specificity was achieved by folic acid functionalization resulting in folate-modified liposomes (FTLiposomes). We demonstrated its specific uptake by fluorescence imaging using folate receptor (FR) overexpressing HeLa and MCF-7 cells as in vitro models. This multifunctional liposome exhibits superior hypoxic anti-tumour effects and holds the potential to reduce side effects associated with untargeted therapy. Fluorescence of the constituent ZnPc and folate-receptor targeting could enable tracking and permit spatiotemporal regulation for improved cancer treatment.
- Full Text:
- Date Issued: 2021
Force Field Parameters for Fe2+ 4S2− 4 Clusters of Dihydropyrimidine Dehydrogenase, the 5-Fluorouracil Cancer Drug Deactivation Protein: A Step towards In Silico Pharmacogenomics Studies
- Tendwa, Maureen B, Chebon-Bore, Lorna, Lobb, Kevin A, Musyoka, Thommas M, Taştan Bishop, Özlem
- Authors: Tendwa, Maureen B , Chebon-Bore, Lorna , Lobb, Kevin A , Musyoka, Thommas M , Taştan Bishop, Özlem
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451078 , vital:75016 , xlink:href="https://doi.org/10.3390/molecules26102929 "
- Description: The dimeric dihydropyrimidine dehydrogenase (DPD), metalloenzyme, an adjunct anti-cancer drug target, contains highly specialized 4 × Fe2+4S2−4 clusters per chain. These clusters facilitate the catalysis of the rate-limiting step in the pyrimidine degradation pathway through a harmonized electron transfer cascade that triggers a redox catabolic reaction. In the process, the bulk of the administered 5-fluorouracil (5-FU) cancer drug is inactivated, while a small proportion is activated to nucleic acid antimetabolites. The occurrence of missense mutations in DPD protein within the general population, including those of African descent, has adverse toxicity effects due to altered 5-FU metabolism. Thus, deciphering mutation effects on protein structure and function is vital, especially for precision medicine purposes. We previously proposed combining molecular dynamics (MD) and dynamic residue network (DRN) analysis to decipher the molecular mechanisms of missense mutations in other proteins. However, the presence of Fe2+4S2−4 clusters in DPD poses a challenge for such in silico studies. The existing AMBER force field parameters cannot accurately describe the Fe2+ center coordination exhibited by this enzyme. Therefore, this study aimed to derive AMBER force field parameters for DPD enzyme Fe2+ centers, using the original Seminario method and the collation features Visual Force Field Derivation Toolkit as a supportive approach. All-atom MD simulations were performed to validate the results. Both approaches generated similar force field parameters, which accurately described the human DPD protein Fe2+4S2−4 cluster architecture. This information is crucial and opens new avenues for in silico cancer pharmacogenomics and drug discovery related research on 5-FU drug efficacy and toxicity issues.
- Full Text:
- Date Issued: 2021
- Authors: Tendwa, Maureen B , Chebon-Bore, Lorna , Lobb, Kevin A , Musyoka, Thommas M , Taştan Bishop, Özlem
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/451078 , vital:75016 , xlink:href="https://doi.org/10.3390/molecules26102929 "
- Description: The dimeric dihydropyrimidine dehydrogenase (DPD), metalloenzyme, an adjunct anti-cancer drug target, contains highly specialized 4 × Fe2+4S2−4 clusters per chain. These clusters facilitate the catalysis of the rate-limiting step in the pyrimidine degradation pathway through a harmonized electron transfer cascade that triggers a redox catabolic reaction. In the process, the bulk of the administered 5-fluorouracil (5-FU) cancer drug is inactivated, while a small proportion is activated to nucleic acid antimetabolites. The occurrence of missense mutations in DPD protein within the general population, including those of African descent, has adverse toxicity effects due to altered 5-FU metabolism. Thus, deciphering mutation effects on protein structure and function is vital, especially for precision medicine purposes. We previously proposed combining molecular dynamics (MD) and dynamic residue network (DRN) analysis to decipher the molecular mechanisms of missense mutations in other proteins. However, the presence of Fe2+4S2−4 clusters in DPD poses a challenge for such in silico studies. The existing AMBER force field parameters cannot accurately describe the Fe2+ center coordination exhibited by this enzyme. Therefore, this study aimed to derive AMBER force field parameters for DPD enzyme Fe2+ centers, using the original Seminario method and the collation features Visual Force Field Derivation Toolkit as a supportive approach. All-atom MD simulations were performed to validate the results. Both approaches generated similar force field parameters, which accurately described the human DPD protein Fe2+4S2−4 cluster architecture. This information is crucial and opens new avenues for in silico cancer pharmacogenomics and drug discovery related research on 5-FU drug efficacy and toxicity issues.
- Full Text:
- Date Issued: 2021
Formative Assessment for Quality Environmental Learning in Natural Sciences Classrooms
- Mgoqi, Nomvuyo, Schudel, Ingrid J
- Authors: Mgoqi, Nomvuyo , Schudel, Ingrid J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435127 , vital:73132 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: The study that informs this chapter aimed at exploring how teachers used formative assessment strategies to support higher order thinking in environmental topics taught in Natural Sciences classrooms (Mgoqi 2019). Higher order thinking is used widely by educational curriculum developers and assessment experts to design test items that measure a variety of thinking skills (Haladyna 2004). For example, the Curriculum Assessment Policy Statement (CAPS) Natural Sciences developers have framed low, middle and high order cognitive levels for guiding classroom assessment (South Africa DBE 2011). These levels describe the way in which learners are expected to work with knowledge as follows: knowing (low order); understanding and applying (medium order); and evaluating, analysing and synthesising (high order). These cognitive levels are closely linked to Bloom’s Taxonomy of Learning which Zohar and Dori (2003) used to describe higher order thinking as analysing, evaluating and creating. These latter three levels build on the lower order thinking levels of remembering, understanding and applying. These higher order thinking skills are important for environmental learning which promotes ‘critical thinking, understanding complex systems, imagining future scenarios, and making decisions in a participatory and collaborative way’ (Unesco 2014: 33). In this chapter, a revised Bloom’s Taxonomy as proposed by Krathwohl (2002) is discussed and used as a lens to review the cognitive levels evident in the activities planned and implemented by teachers.
- Full Text:
- Date Issued: 2021
- Authors: Mgoqi, Nomvuyo , Schudel, Ingrid J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/435127 , vital:73132 , ISBN 9781928502241 , https://library.oapen.org/handle/20.500.12657/64082
- Description: The study that informs this chapter aimed at exploring how teachers used formative assessment strategies to support higher order thinking in environmental topics taught in Natural Sciences classrooms (Mgoqi 2019). Higher order thinking is used widely by educational curriculum developers and assessment experts to design test items that measure a variety of thinking skills (Haladyna 2004). For example, the Curriculum Assessment Policy Statement (CAPS) Natural Sciences developers have framed low, middle and high order cognitive levels for guiding classroom assessment (South Africa DBE 2011). These levels describe the way in which learners are expected to work with knowledge as follows: knowing (low order); understanding and applying (medium order); and evaluating, analysing and synthesising (high order). These cognitive levels are closely linked to Bloom’s Taxonomy of Learning which Zohar and Dori (2003) used to describe higher order thinking as analysing, evaluating and creating. These latter three levels build on the lower order thinking levels of remembering, understanding and applying. These higher order thinking skills are important for environmental learning which promotes ‘critical thinking, understanding complex systems, imagining future scenarios, and making decisions in a participatory and collaborative way’ (Unesco 2014: 33). In this chapter, a revised Bloom’s Taxonomy as proposed by Krathwohl (2002) is discussed and used as a lens to review the cognitive levels evident in the activities planned and implemented by teachers.
- Full Text:
- Date Issued: 2021
From introduction to nuisance growth: A review of traits of alien aquatic plants which contribute to their invasiveness
- Hussner, Andreas, Heidbuchel, Patrick, Coetzee, Julie A, Gross, Elisabeth M
- Authors: Hussner, Andreas , Heidbuchel, Patrick , Coetzee, Julie A , Gross, Elisabeth M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424006 , vital:72115 , xlink:href="https://doi.org/10.1007/s10750-020-04463-z"
- Description: Invasive alien aquatic plant species (IAAPs) cause serious ecological and economic impact and are a major driver of changes in aquatic plant communities. Their invasive success is influenced by both abiotic and biotic factors. Here, we summarize the existing knowledge on the biology of 21 IAAPs (four free-floating species, eight sediment-rooted, emerged or floating-leaved species, and nine sediment-rooted, submerged species) to highlight traits that are linked to their invasive success. We focus on those traits which were documented as closely linked to plant invasions, including dispersal and growth patterns, allelopathy and herbivore defence. The traits are generally specific to the different growth forms of IAAPs. In general, the species show effective dispersal and spread mechanisms, even though sexual and vegetative spread differs strongly between species. Moreover, IAAPs show varying strategies to cope with the environment. The presented overview of traits of IAAPs will help to identify potential invasive alien aquatic plants. Further, the information provided is of interest for developing species-specific management strategies and effective prevention measures.
- Full Text:
- Date Issued: 2021
- Authors: Hussner, Andreas , Heidbuchel, Patrick , Coetzee, Julie A , Gross, Elisabeth M
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/424006 , vital:72115 , xlink:href="https://doi.org/10.1007/s10750-020-04463-z"
- Description: Invasive alien aquatic plant species (IAAPs) cause serious ecological and economic impact and are a major driver of changes in aquatic plant communities. Their invasive success is influenced by both abiotic and biotic factors. Here, we summarize the existing knowledge on the biology of 21 IAAPs (four free-floating species, eight sediment-rooted, emerged or floating-leaved species, and nine sediment-rooted, submerged species) to highlight traits that are linked to their invasive success. We focus on those traits which were documented as closely linked to plant invasions, including dispersal and growth patterns, allelopathy and herbivore defence. The traits are generally specific to the different growth forms of IAAPs. In general, the species show effective dispersal and spread mechanisms, even though sexual and vegetative spread differs strongly between species. Moreover, IAAPs show varying strategies to cope with the environment. The presented overview of traits of IAAPs will help to identify potential invasive alien aquatic plants. Further, the information provided is of interest for developing species-specific management strategies and effective prevention measures.
- Full Text:
- Date Issued: 2021
Futures analysis
- Hichert, Tanya, Biggs, Reinette, de Vos, Alta
- Authors: Hichert, Tanya , Biggs, Reinette , de Vos, Alta
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433871 , vital:73006 , ISBN 9781000401516 , https://library.oapen.org/handle/20.500.12657/49560
- Description: Futures analysis methods can help people to think constructively and systematically about the future and advance our understanding of change and uncertainty in complex social-ecological systems (SES). This is important because there is not one single predictable future but multiple ones, depending on the complex, unpredictable interplays and interactions of actors, institutions, ecological processes and other elements of the system and its dynamics. Actively developing ideas, images and/or stories about different futures can enable us to make different choices and take different actions in the present in relation to, for example, risk mitigation, adaptation, resource allocation and strategy development, which can help build more sustainable and just futures.
- Full Text:
- Date Issued: 2021
- Authors: Hichert, Tanya , Biggs, Reinette , de Vos, Alta
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , book chapter
- Identifier: http://hdl.handle.net/10962/433871 , vital:73006 , ISBN 9781000401516 , https://library.oapen.org/handle/20.500.12657/49560
- Description: Futures analysis methods can help people to think constructively and systematically about the future and advance our understanding of change and uncertainty in complex social-ecological systems (SES). This is important because there is not one single predictable future but multiple ones, depending on the complex, unpredictable interplays and interactions of actors, institutions, ecological processes and other elements of the system and its dynamics. Actively developing ideas, images and/or stories about different futures can enable us to make different choices and take different actions in the present in relation to, for example, risk mitigation, adaptation, resource allocation and strategy development, which can help build more sustainable and just futures.
- Full Text:
- Date Issued: 2021
God Abhors Corruption: Some Thoughts on Acts 5:1-11 with special reference to the South African Countercorruption Efforts
- Authors: Speckman, McGlory
- Date: 2021
- Subjects: Corruption South Africa God Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7060 , vital:52805 , xlink:href=":https://doi.org/10.46222/pharosjot.102.036"
- Description: Corruption has become a buzz word the world-over today. South Africa is no less affected by it than are other countries. Many counter-corruption measures have been devised from a political perspective with no visible results. This reflection is an attempt to introduce a religious intervention. The article argues that the narrative of Ananias and Sapphira (Acts: 1-11) has all the elements of corruption as we know it today as well as a decisive response to it. Redaction criticism is employed in reading the narrative of Ananias and Sapphira with particular reference to the South African counter-corruption efforts. The reading reveals that God abhors corruption, this being inferred from the ‘double-deaths’ of the corrupt couple. A conclusion is therefore reached that drastic action against perpetrators is imperative and that trustees of state authority who fail to act against corruption and its perpetrators do not deserve to be rewarded with office. Keywords: corruption, counter-corruption efforts, Acts 5:1-11, consequence management, Ananias and Sapphira, koinonia community, South Africa
- Full Text:
- Date Issued: 2021
- Authors: Speckman, McGlory
- Date: 2021
- Subjects: Corruption South Africa God Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/7060 , vital:52805 , xlink:href=":https://doi.org/10.46222/pharosjot.102.036"
- Description: Corruption has become a buzz word the world-over today. South Africa is no less affected by it than are other countries. Many counter-corruption measures have been devised from a political perspective with no visible results. This reflection is an attempt to introduce a religious intervention. The article argues that the narrative of Ananias and Sapphira (Acts: 1-11) has all the elements of corruption as we know it today as well as a decisive response to it. Redaction criticism is employed in reading the narrative of Ananias and Sapphira with particular reference to the South African counter-corruption efforts. The reading reveals that God abhors corruption, this being inferred from the ‘double-deaths’ of the corrupt couple. A conclusion is therefore reached that drastic action against perpetrators is imperative and that trustees of state authority who fail to act against corruption and its perpetrators do not deserve to be rewarded with office. Keywords: corruption, counter-corruption efforts, Acts 5:1-11, consequence management, Ananias and Sapphira, koinonia community, South Africa
- Full Text:
- Date Issued: 2021
Grand challenges in urban agriculture: ecological and social approaches to transformative sustainability
- Zimmerer, Karl S, Bell, Martha G, Chirisa, Innocent, Duvall, Chris S, Egerer, Monika, Hung, Po-Yi, Lerner, Amy M, Shackleton, Charlie M, Ward, James D, Ochoa, Carolina Y
- Authors: Zimmerer, Karl S , Bell, Martha G , Chirisa, Innocent , Duvall, Chris S , Egerer, Monika , Hung, Po-Yi , Lerner, Amy M , Shackleton, Charlie M , Ward, James D , Ochoa, Carolina Y
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402287 , vital:69838 , xlink:href="https://doi.org/10.3389/fsufs.2021.668561"
- Description: This synopsis of the Grand Challenges of Urban Agriculture (UA) is framed by the urgent need to understand and strengthen the expanding yet highly diverse roles of UA amid rapid global urbanization, failures of predominant food systems, and crises in systems of physical and mental health. More than half of humanity lives in cities today and by 2030 this is projected to grow to 60.4 percent, ∼5 billion people (UN Habitat, 2020). More than 90 percent of urban demographic increase is anticipated to take place in the developing world. Ecological and social dimensions of UA are situated in these expanding spaces of cities, towns, and villages (along with their urban fringe or peri-urban areas), and among their diverse populations. UA is further situated in the powerful, far-reaching influences of urbanization processes that occur within and beyond these spaces. UA is thus integral to the prospect of Urban Sustainability as SDG 11 (“Make cities and human settlements inclusive, safe, resilient and sustainable”) of the U.N.’s 2030 Agenda for Sustainable Development.
- Full Text:
- Date Issued: 2021
- Authors: Zimmerer, Karl S , Bell, Martha G , Chirisa, Innocent , Duvall, Chris S , Egerer, Monika , Hung, Po-Yi , Lerner, Amy M , Shackleton, Charlie M , Ward, James D , Ochoa, Carolina Y
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/402287 , vital:69838 , xlink:href="https://doi.org/10.3389/fsufs.2021.668561"
- Description: This synopsis of the Grand Challenges of Urban Agriculture (UA) is framed by the urgent need to understand and strengthen the expanding yet highly diverse roles of UA amid rapid global urbanization, failures of predominant food systems, and crises in systems of physical and mental health. More than half of humanity lives in cities today and by 2030 this is projected to grow to 60.4 percent, ∼5 billion people (UN Habitat, 2020). More than 90 percent of urban demographic increase is anticipated to take place in the developing world. Ecological and social dimensions of UA are situated in these expanding spaces of cities, towns, and villages (along with their urban fringe or peri-urban areas), and among their diverse populations. UA is further situated in the powerful, far-reaching influences of urbanization processes that occur within and beyond these spaces. UA is thus integral to the prospect of Urban Sustainability as SDG 11 (“Make cities and human settlements inclusive, safe, resilient and sustainable”) of the U.N.’s 2030 Agenda for Sustainable Development.
- Full Text:
- Date Issued: 2021
Handwriting Recognition using Deep Learning with Effective Data Augmentation Techniques
- Brown, Dane L, Lidzhade, Ipfi
- Authors: Brown, Dane L , Lidzhade, Ipfi
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465700 , vital:76633 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9519359"
- Description: Machine learning techniques have been successfully used in deciphering handwritten text. Deep learning has made further improvements in this regard. However, they require substantial amounts of training data. This research aims to improve the effectiveness of classification accuracy in the presence of limited training data on handwriting recognition. The main focus thus involves enabling deep models to converge during training on smaller datasets using data augmentation. This will allow for broader use of these systems across more regions, greater accessibility, and future related systems to be less reliant on the amount of data available. Therefore, the proposed research includes an image processing and machine learning approach to handwriting recognition while generating more sample data in various ways. Applying random cropping as an augmentation technique resulted in higher accuracy than several other augmentation techniques examined in this paper. Some of these techniques performed worse than on unaugmented data.
- Full Text:
- Date Issued: 2021
- Authors: Brown, Dane L , Lidzhade, Ipfi
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/465700 , vital:76633 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9519359"
- Description: Machine learning techniques have been successfully used in deciphering handwritten text. Deep learning has made further improvements in this regard. However, they require substantial amounts of training data. This research aims to improve the effectiveness of classification accuracy in the presence of limited training data on handwriting recognition. The main focus thus involves enabling deep models to converge during training on smaller datasets using data augmentation. This will allow for broader use of these systems across more regions, greater accessibility, and future related systems to be less reliant on the amount of data available. Therefore, the proposed research includes an image processing and machine learning approach to handwriting recognition while generating more sample data in various ways. Applying random cropping as an augmentation technique resulted in higher accuracy than several other augmentation techniques examined in this paper. Some of these techniques performed worse than on unaugmented data.
- Full Text:
- Date Issued: 2021
Happy without money: Minimally monetized societies can exhibit high subjective well-being
- Miñarro, Sara, Reyes-García V, Aswani, Shankar, Selim, Samiya, Barrington-Leigh, Christopher P, Galbraith, Eric D
- Authors: Miñarro, Sara , Reyes-García V , Aswani, Shankar , Selim, Samiya , Barrington-Leigh, Christopher P , Galbraith, Eric D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403430 , vital:69960 , xlink:href="https://doi.org/10.1371/journal.pone.0244569"
- Description: Economic growth is often assumed to improve happiness for people in low income countries, although the association between monetary income and subjective well-being has been a subject of debate. We test this assumption by comparing three different measures of subjective well-being in very low-income communities with different levels of monetization. Contrary to expectations, all three measures of subjective well-being were very high in the least-monetized sites and comparable to those found among citizens of wealthy nations. The reported drivers of happiness shifted with increasing monetization: from enjoying experiential activities in contact with nature at the less monetized sites, to social and economic factors at the more monetized sites. Our results suggest that high levels of subjective well-being can be achieved with minimal monetization, challenging the perception that economic growth will raise life satisfaction among low income populations.
- Full Text:
- Date Issued: 2021
- Authors: Miñarro, Sara , Reyes-García V , Aswani, Shankar , Selim, Samiya , Barrington-Leigh, Christopher P , Galbraith, Eric D
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/403430 , vital:69960 , xlink:href="https://doi.org/10.1371/journal.pone.0244569"
- Description: Economic growth is often assumed to improve happiness for people in low income countries, although the association between monetary income and subjective well-being has been a subject of debate. We test this assumption by comparing three different measures of subjective well-being in very low-income communities with different levels of monetization. Contrary to expectations, all three measures of subjective well-being were very high in the least-monetized sites and comparable to those found among citizens of wealthy nations. The reported drivers of happiness shifted with increasing monetization: from enjoying experiential activities in contact with nature at the less monetized sites, to social and economic factors at the more monetized sites. Our results suggest that high levels of subjective well-being can be achieved with minimal monetization, challenging the perception that economic growth will raise life satisfaction among low income populations.
- Full Text:
- Date Issued: 2021
Heavy metal profiles in limpets and algae on the Eastern Cape coast of South Africa
- N Mbandzi, N., Nakin, MDV., Saibu, GM, Oyedeji, AO
- Authors: N Mbandzi, N. , Nakin, MDV. , Saibu, GM , Oyedeji, AO
- Date: 2021
- Subjects: Marine Pollution Bioaccumulation Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6936 , vital:52572 , xlink:href="https://doi.org/10.2989/1814232X.2021.1948918"
- Description: Heavy metal pollution is an increasing threat to the marine environment and is a major health concern. Both marine limpets and algae have been employed as biomonitors elsewhere in the world, but there are few or no data for these taxa along the South African coast. We investigated heavy metal concentrations in the tissues of selected limpet and algae species sampled at four sites on the southeast coast of South Africa (Silaka, Hluleka, Mthatha and Mbhashe), and determined whether there was any relationship between heavy metal concentrations in the limpets and their algae food sources as evidenced by the trophic transfer factor (TTF). Samples were collected in July 2019 and the tissues were digested following normal protocols. Heavy metals were detected using inductively coupled plasma optical emission spectrometry (ICP-OES). Significant differences in metal concentrations were observed among the algae species. The soft tissues of limpets from Silaka had the highest heavy metal concentrations, and samples from Mthatha had the lowest, with only mercury (Hg) occurring in high concentrations. Metal concentrations in soft tissues were generally 10-times higher than in shell tissues and differed between lower- and upper-shore species. Cadmium (Cd) biomagnified (TTF > 1) in all limpet species at all sites. Cd, arsenic (As), lead (Pb) and Hg measured in our study were above the maximum limits set by the South African Department of Health. This study suggests that the use of limpet and algae species as bioindicators is feasible since they are widely distributed and can accumulate a wide range of heavy metals.
- Full Text:
- Date Issued: 2021
- Authors: N Mbandzi, N. , Nakin, MDV. , Saibu, GM , Oyedeji, AO
- Date: 2021
- Subjects: Marine Pollution Bioaccumulation Article
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/11260/6936 , vital:52572 , xlink:href="https://doi.org/10.2989/1814232X.2021.1948918"
- Description: Heavy metal pollution is an increasing threat to the marine environment and is a major health concern. Both marine limpets and algae have been employed as biomonitors elsewhere in the world, but there are few or no data for these taxa along the South African coast. We investigated heavy metal concentrations in the tissues of selected limpet and algae species sampled at four sites on the southeast coast of South Africa (Silaka, Hluleka, Mthatha and Mbhashe), and determined whether there was any relationship between heavy metal concentrations in the limpets and their algae food sources as evidenced by the trophic transfer factor (TTF). Samples were collected in July 2019 and the tissues were digested following normal protocols. Heavy metals were detected using inductively coupled plasma optical emission spectrometry (ICP-OES). Significant differences in metal concentrations were observed among the algae species. The soft tissues of limpets from Silaka had the highest heavy metal concentrations, and samples from Mthatha had the lowest, with only mercury (Hg) occurring in high concentrations. Metal concentrations in soft tissues were generally 10-times higher than in shell tissues and differed between lower- and upper-shore species. Cadmium (Cd) biomagnified (TTF > 1) in all limpet species at all sites. Cd, arsenic (As), lead (Pb) and Hg measured in our study were above the maximum limits set by the South African Department of Health. This study suggests that the use of limpet and algae species as bioindicators is feasible since they are widely distributed and can accumulate a wide range of heavy metals.
- Full Text:
- Date Issued: 2021
High-Level Modelling for Typed Functional Programming
- Authors: Motara, Yusuf, M
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429035 , vital:72555 , https://doi.org/10.1007/978-3-030-83978-9_4
- Description: There is currently no way to model the high-level structural design of a functional system. Given the strong links between functional programming and mathematics, it is hypothesised that the language of mathematics can provide insight into how a functional system might be modelled. The approach is successful and both philosophy and the language of mathematics are used to identify the necessary modelling concepts and briefly outline some modelling notation alongside a small case study.
- Full Text:
- Date Issued: 2021
- Authors: Motara, Yusuf, M
- Date: 2021
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429035 , vital:72555 , https://doi.org/10.1007/978-3-030-83978-9_4
- Description: There is currently no way to model the high-level structural design of a functional system. Given the strong links between functional programming and mathematics, it is hypothesised that the language of mathematics can provide insight into how a functional system might be modelled. The approach is successful and both philosophy and the language of mathematics are used to identify the necessary modelling concepts and briefly outline some modelling notation alongside a small case study.
- Full Text:
- Date Issued: 2021
High-resolution geological, petrological and geochemical investigation of the mid mid-lower c. 3.3 Ga Kromberg type type-section, Barberton greenstone belt, South Africa Africa
- Authors: Ndlela, Sibusisiwe
- Date: 2021
- Subjects: Petrology -- Eswatini and South Africa -- Barberton Greenstone Belt , Geology -- Eswatini and South Africa -- Barberton Greenstone Belt , Geochemistry -- Eswatini and South Africa -- Barberton Greenstone Belt , Onverwacht Group (South Africa) , Barberton Greenstone Belt (Eswatini and South Africa) , Groups (Stratigraph) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172241 , vital:42179
- Description: The geology of the SE limb of the Kromberg type-section, its origin and its evolution has remained controversial for more than five decades since its discovery by Viljoen and Viljoen (1969). Different lithostratigraphy and geodynamic models have been proposed that were centred around two end-member models, a continuous layer-cake stratigraphy model (Viljoen and Viljoen, 1969c, Lowe et al., 1999) or a tectono-stratigraphic model (de Wit et al., 2011, Furnes et al., 2012). Additionally, the Kromberg type-section mafic-ultramafic sequence represents a relatively thin, dismembered sequence compared to other formations or ‘complexes’ in the Onverwacht Group. Previous geology workers relied on the field interpretations for the construction of the geological architecture of the Kromberg type-section; but no petrographic analyses were conducted for accurate, integrated geological characterization of different rock compositions. To address controversies centred around the Kromberg type-section geology and geodynamic setting, this study is aimed at testing previously proposed stratigraphic and geodynamic models by integrating high-resolution geological mapping, petrography, mineral chemistry and whole-rock geochemistry to verify rock characterization. The aim is to accurately reconstruct the volcano-sedimentary architecture of the Kromberg type-section and to compare this to the results of previous fieldwork. Moreover, the manner in which the Kromberg sequence may relate to current Archean geodynamic models is evaluated, and a new model explaining the origin and evolution of the Kromberg type sequence is proposed. The integration of high-resolution field mapping, petrography and geochemistry has allowed for a high precision study and that has resulted in the construction of a new geological architecture for the SE limb of the Kromberg type-section. The stratigraphic thickness of the SE limb of the Kromberg sequence comprises dominant c. 80% volcanic rocks and minor c. 15% intrusive rocks, intercalated by 7 volcano-sedimentary chert horizons (c. 5%). Four main rock types (groups) are present in the Kromberg type-section with two sub-types of komatiitic basalts (the Badplaas-type and Geluk-types), Fe-rich tholeiitic basalt, cumulate peridotite, and a metadunite. Although the Kromberg type-section records sub-greenschist to lower greenschist facies, more than 50% of the rock samples classify as altered with parts of the stratigraphy recording extensive chloritization and severe ocean-floor silicification. Geochemical data revealed an enrichment in SiO2, K2O, Ba, Rb and variation in HREE for highly silicified samples whereas, chloritized samples are enriched in FeO and have concave upward LREE patterns. Partially chloritized tholeiites and komatiitic basalts have overlapping SiO2 signatures, relatively flat REE patterns and a small negative Nb anomaly in the primitive mantle-normalized spider diagrams. This thesis provides the first Lu-Hf isotope data on whole rock samples from the Kromberg type-section. The εHf values at t=3.33 Ga range between -0.62 to +4.18 and Hf model ages range between 3.43 - 4.27 Ga. The rock compositions are compared to the geochemistry of other greenstone belt rocks, which are considered to provide insight onto the geodynamic setting under which the Kromberg mafic-ultramafic sequence formed. The rock compositions reveal plume-related processes where a primitive mantle melt interacts with recycled mafic crust or mafic lower crust of older units of the Onverwacht Group. Only a small Nb anomaly is found in some samples and the data plots outside the subduction zone (forearc and back-arc) field. Rare-Earth element profiles are flat and not consistent with a subduction zone signature, as proposed in previous studies. Rifting of an oceanic floor in a juvenile basin is proposed for the formation of the Kromberg type-section rocks, prior to being tectonically accreted during regional transpressional deformation at c. 3.23 Ga.
- Full Text:
- Date Issued: 2021
- Authors: Ndlela, Sibusisiwe
- Date: 2021
- Subjects: Petrology -- Eswatini and South Africa -- Barberton Greenstone Belt , Geology -- Eswatini and South Africa -- Barberton Greenstone Belt , Geochemistry -- Eswatini and South Africa -- Barberton Greenstone Belt , Onverwacht Group (South Africa) , Barberton Greenstone Belt (Eswatini and South Africa) , Groups (Stratigraph) -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172241 , vital:42179
- Description: The geology of the SE limb of the Kromberg type-section, its origin and its evolution has remained controversial for more than five decades since its discovery by Viljoen and Viljoen (1969). Different lithostratigraphy and geodynamic models have been proposed that were centred around two end-member models, a continuous layer-cake stratigraphy model (Viljoen and Viljoen, 1969c, Lowe et al., 1999) or a tectono-stratigraphic model (de Wit et al., 2011, Furnes et al., 2012). Additionally, the Kromberg type-section mafic-ultramafic sequence represents a relatively thin, dismembered sequence compared to other formations or ‘complexes’ in the Onverwacht Group. Previous geology workers relied on the field interpretations for the construction of the geological architecture of the Kromberg type-section; but no petrographic analyses were conducted for accurate, integrated geological characterization of different rock compositions. To address controversies centred around the Kromberg type-section geology and geodynamic setting, this study is aimed at testing previously proposed stratigraphic and geodynamic models by integrating high-resolution geological mapping, petrography, mineral chemistry and whole-rock geochemistry to verify rock characterization. The aim is to accurately reconstruct the volcano-sedimentary architecture of the Kromberg type-section and to compare this to the results of previous fieldwork. Moreover, the manner in which the Kromberg sequence may relate to current Archean geodynamic models is evaluated, and a new model explaining the origin and evolution of the Kromberg type sequence is proposed. The integration of high-resolution field mapping, petrography and geochemistry has allowed for a high precision study and that has resulted in the construction of a new geological architecture for the SE limb of the Kromberg type-section. The stratigraphic thickness of the SE limb of the Kromberg sequence comprises dominant c. 80% volcanic rocks and minor c. 15% intrusive rocks, intercalated by 7 volcano-sedimentary chert horizons (c. 5%). Four main rock types (groups) are present in the Kromberg type-section with two sub-types of komatiitic basalts (the Badplaas-type and Geluk-types), Fe-rich tholeiitic basalt, cumulate peridotite, and a metadunite. Although the Kromberg type-section records sub-greenschist to lower greenschist facies, more than 50% of the rock samples classify as altered with parts of the stratigraphy recording extensive chloritization and severe ocean-floor silicification. Geochemical data revealed an enrichment in SiO2, K2O, Ba, Rb and variation in HREE for highly silicified samples whereas, chloritized samples are enriched in FeO and have concave upward LREE patterns. Partially chloritized tholeiites and komatiitic basalts have overlapping SiO2 signatures, relatively flat REE patterns and a small negative Nb anomaly in the primitive mantle-normalized spider diagrams. This thesis provides the first Lu-Hf isotope data on whole rock samples from the Kromberg type-section. The εHf values at t=3.33 Ga range between -0.62 to +4.18 and Hf model ages range between 3.43 - 4.27 Ga. The rock compositions are compared to the geochemistry of other greenstone belt rocks, which are considered to provide insight onto the geodynamic setting under which the Kromberg mafic-ultramafic sequence formed. The rock compositions reveal plume-related processes where a primitive mantle melt interacts with recycled mafic crust or mafic lower crust of older units of the Onverwacht Group. Only a small Nb anomaly is found in some samples and the data plots outside the subduction zone (forearc and back-arc) field. Rare-Earth element profiles are flat and not consistent with a subduction zone signature, as proposed in previous studies. Rifting of an oceanic floor in a juvenile basin is proposed for the formation of the Kromberg type-section rocks, prior to being tectonically accreted during regional transpressional deformation at c. 3.23 Ga.
- Full Text:
- Date Issued: 2021
Higher temperatures are associated with reduced nestling body condition in a range restricted mountain bird
- Oswald, Krista N, Smit, Ben, Lee, Alan T K, Peng, Ceili L, Brock, Cameryn, Cunningham, Susan J
- Authors: Oswald, Krista N , Smit, Ben , Lee, Alan T K , Peng, Ceili L , Brock, Cameryn , Cunningham, Susan J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440547 , vital:73791 , https://doi.org/10.1111/jav.02756
- Description: Demonstrated negative effects of increased temperatures on avian reproductive success suggest a mechanism by which climate change may impact species persistence. High temperatures can result in reduced parental care and reduced nestling condition in passerines with dependent young, resulting in lowered fledging success and population recruitment. We examined provisioning rate and nestling condition in a South African mountain endemic, the Cape rockjumper Chaetops frenatus, whose population declines correlate with warming habitat. Our aim was to determine whether rockjumper reproductive success could be affected by high air temperatures. We set up video cameras on nests at three nestling age classes (≤ 7 days old; 8–12 days old; ≥ 13 days old) for 8 hours on 37 separate days.
- Full Text:
- Date Issued: 2021
- Authors: Oswald, Krista N , Smit, Ben , Lee, Alan T K , Peng, Ceili L , Brock, Cameryn , Cunningham, Susan J
- Date: 2021
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/440547 , vital:73791 , https://doi.org/10.1111/jav.02756
- Description: Demonstrated negative effects of increased temperatures on avian reproductive success suggest a mechanism by which climate change may impact species persistence. High temperatures can result in reduced parental care and reduced nestling condition in passerines with dependent young, resulting in lowered fledging success and population recruitment. We examined provisioning rate and nestling condition in a South African mountain endemic, the Cape rockjumper Chaetops frenatus, whose population declines correlate with warming habitat. Our aim was to determine whether rockjumper reproductive success could be affected by high air temperatures. We set up video cameras on nests at three nestling age classes (≤ 7 days old; 8–12 days old; ≥ 13 days old) for 8 hours on 37 separate days.
- Full Text:
- Date Issued: 2021