Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
A 150 MHz all sky survey with the Precision Array to Probe the Epoch of Reionization
- Authors: Chege, James Kariuki
- Date: 2020
- Subjects: Epoch of reionization -- Research , Astronomy -- Observations , Radio interferometers
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117733 , vital:34556
- Description: The Precision Array to Probe the Epoch of Reionization (PAPER) was built to measure the redshifted 21 cm line of hydrogen from cosmic reionization. Such low frequency observations promise to be the best means of understanding the cosmic dawn; when the first galaxies in the universe formed, and also the Epoch of Reionization; when the intergalactic medium changed from neutral to ionized. The major challenges to these observations is the presence of astrophysical foregrounds that are much brighter than the cosmological signal. Here, I present an all-sky survey at 150 MHz obtained from the analysis of 300 hours of PAPER observations. Particular focus is given to the calibration and imaging techniques that need to deal with the wide field of view of a non-tracking instrument. The survey covers ~ 7000 square degrees of the southern sky. From a sky area of 4400 square degrees out of the total survey area, I extract a catalogue of sources brighter than 4 Jy whose accuracy was tested against the published GLEAM catalogue, leading to a fractional difference rms better than 20%. The catalogue provides an all-sky accurate model of the extragalactic foreground to be used for the calibration of future Epoch of Reionization observations and to be subtracted from the PAPER observations themselves in order to mitigate the foreground contamination.
- Full Text:
- Date Issued: 2020
- Authors: Chege, James Kariuki
- Date: 2020
- Subjects: Epoch of reionization -- Research , Astronomy -- Observations , Radio interferometers
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/117733 , vital:34556
- Description: The Precision Array to Probe the Epoch of Reionization (PAPER) was built to measure the redshifted 21 cm line of hydrogen from cosmic reionization. Such low frequency observations promise to be the best means of understanding the cosmic dawn; when the first galaxies in the universe formed, and also the Epoch of Reionization; when the intergalactic medium changed from neutral to ionized. The major challenges to these observations is the presence of astrophysical foregrounds that are much brighter than the cosmological signal. Here, I present an all-sky survey at 150 MHz obtained from the analysis of 300 hours of PAPER observations. Particular focus is given to the calibration and imaging techniques that need to deal with the wide field of view of a non-tracking instrument. The survey covers ~ 7000 square degrees of the southern sky. From a sky area of 4400 square degrees out of the total survey area, I extract a catalogue of sources brighter than 4 Jy whose accuracy was tested against the published GLEAM catalogue, leading to a fractional difference rms better than 20%. The catalogue provides an all-sky accurate model of the extragalactic foreground to be used for the calibration of future Epoch of Reionization observations and to be subtracted from the PAPER observations themselves in order to mitigate the foreground contamination.
- Full Text:
- Date Issued: 2020
Reliving it through pen
- Authors: Chidi, Tsosheletso
- Date: 2020
- Subjects: South African fiction (English) , Northern Sotho poetry
- Language: English , Northern Sotho
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/163566 , vital:41049
- Description: This document consists of two parts: PART A: English Half Thesis (Creative Work) PART B: Dual Language Portfolio (Sepedi and English). This thesis focuses on witnessing the trauma of rape, inability to move on, denial and attempt to forget, it draws attention also to emotional abuse in a place called home, death and place. My work is influenced by Carolyn Fourche’s anthology, Against Forgetting: Poetry of Witness, Adam Bradley and Andrew Dubois’s The Anthology of the Rap, as well as Lesego Rampolokeng poem “Welcome to New Consciousness”.
- Full Text:
- Date Issued: 2020
- Authors: Chidi, Tsosheletso
- Date: 2020
- Subjects: South African fiction (English) , Northern Sotho poetry
- Language: English , Northern Sotho
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/163566 , vital:41049
- Description: This document consists of two parts: PART A: English Half Thesis (Creative Work) PART B: Dual Language Portfolio (Sepedi and English). This thesis focuses on witnessing the trauma of rape, inability to move on, denial and attempt to forget, it draws attention also to emotional abuse in a place called home, death and place. My work is influenced by Carolyn Fourche’s anthology, Against Forgetting: Poetry of Witness, Adam Bradley and Andrew Dubois’s The Anthology of the Rap, as well as Lesego Rampolokeng poem “Welcome to New Consciousness”.
- Full Text:
- Date Issued: 2020
Formulation and characterisation of a combination captopril and hydrochlorothiazide microparticulate dosage form for paediatric use
- Chikukwa, Mellisa Tafadzwa Ruramai
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
- Authors: Chikukwa, Mellisa Tafadzwa Ruramai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163216 , vital:41019 , doi:10.21504/10962/163216
- Description: Thesis (PhD)--Rhodes University, Pharmacy Faculty, Department of Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
Development of graphene materials and phthalocyanines for application in dye-sensitized solar cells
- Authors: Chindeka, Francis
- Date: 2020
- Subjects: Dye-sensitized solar cells , Graphene , Phthalocyanines , Molecular orbitals , Impedance spectroscopy
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166092 , vital:41328
- Description: Two sets of dye-sensitized solar cells (DSSCs) were fabricated. In the first set, dye-sensitized solar cells (DSSC) were fabricated by incorporating graphene materials as catalysts at the counter electrode. Platinum was also used as a catalyst for comparative purposes. Different phthalocyanines: hydroxyl indium tetracarboxyphenoxy phthalocyanine (1), chloro indium octacarboxy phthalocyanine (2) and dibenzoic acid silicon phthalocyanine (3) were used as dyes. Complex 3 gave the highest power conversion efficiency (η) of 3.19% when using nitrogen doped reduced graphene oxide nanosheets (NrGONS) as a catalyst at the counter electrode, and TiO2 containing rGONS at the anode. The value obtained is close to 3.8% obtained when using Pt catalyst instead of NrGONS at the cathode, thus confirming that NrGONS is a promising candidate to replace the more expensive Pt. The study also shows that placing rGONS on both the anode and cathode improves efficiency. In the second set, 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 (4) 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) showed significant improvement on the performance of the DSSC compared to previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
- Full Text:
- Date Issued: 2020
- Authors: Chindeka, Francis
- Date: 2020
- Subjects: Dye-sensitized solar cells , Graphene , Phthalocyanines , Molecular orbitals , Impedance spectroscopy
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/166092 , vital:41328
- Description: Two sets of dye-sensitized solar cells (DSSCs) were fabricated. In the first set, dye-sensitized solar cells (DSSC) were fabricated by incorporating graphene materials as catalysts at the counter electrode. Platinum was also used as a catalyst for comparative purposes. Different phthalocyanines: hydroxyl indium tetracarboxyphenoxy phthalocyanine (1), chloro indium octacarboxy phthalocyanine (2) and dibenzoic acid silicon phthalocyanine (3) were used as dyes. Complex 3 gave the highest power conversion efficiency (η) of 3.19% when using nitrogen doped reduced graphene oxide nanosheets (NrGONS) as a catalyst at the counter electrode, and TiO2 containing rGONS at the anode. The value obtained is close to 3.8% obtained when using Pt catalyst instead of NrGONS at the cathode, thus confirming that NrGONS is a promising candidate to replace the more expensive Pt. The study also shows that placing rGONS on both the anode and cathode improves efficiency. In the second set, 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 (4) 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) showed significant improvement on the performance of the DSSC compared to previous work on symmetrical carboxylated phthalocyanines with ɳ = 3.19%.
- Full Text:
- Date Issued: 2020
An investigation into the readiness of open source software to build a Telco Cloud for virtualising network functions
- Authors: Chindeka, Tapiwa C
- Date: 2020
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/124320 , vital:35593
- Description: Cloud computing offers new mechanisms that change the way networks can be created and managed. The increased demand for multimedia and Internet of Things (IoT) services using the Internet Protocol is also fueling the need to look more into a networking approach that is less reliant on physical hardware components and allows new networks and network components to be created on-demand. Network Function Virtualisation (NFV) is a networking paradigm that decouples network functions from the hardware on which they run on. This offers new approaches to telecommunication providers who are looking to new ways of improving Quality of Service (QoS) in cost effective ways. Cloud technologies have given way to more specialised cloud environments such as the telco cloud. The telco cloud is a cloud environment where telecommunication services are hosted utilising NFV techniques. As the use of telecommunication standards moves towards 5G, network services will be provided in a virtualised manner in order to keep up with the demand. Open source software is a driver for innovation as it is has a collaborative culture to support it. This research investigates the readiness of open source tools to build a telco cloud that supports functions such as autoscaling and fault tolerance. Currently available open source software was explored for the different aspects involved in building a cloud from the ground up. The ETSI NFV MANO framework is also discussed as it is a widely used guiding standard for implementing NFV. Guided by the ETSI NFV MANO framework, open source software was used in an experiment to build a resilient cloud environment in which a virtualised IP Multimedia Subsystem (vIMS) network was deployed. Through this experimentation, it is evident that open source tools are mature enough to build the cloud environment and its ETSI NFV MANO compliant orchestration. However, features such as autoscaling and fault tolerance are still fairly immature and experimental.
- Full Text:
- Date Issued: 2020
- Authors: Chindeka, Tapiwa C
- Date: 2020
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/124320 , vital:35593
- Description: Cloud computing offers new mechanisms that change the way networks can be created and managed. The increased demand for multimedia and Internet of Things (IoT) services using the Internet Protocol is also fueling the need to look more into a networking approach that is less reliant on physical hardware components and allows new networks and network components to be created on-demand. Network Function Virtualisation (NFV) is a networking paradigm that decouples network functions from the hardware on which they run on. This offers new approaches to telecommunication providers who are looking to new ways of improving Quality of Service (QoS) in cost effective ways. Cloud technologies have given way to more specialised cloud environments such as the telco cloud. The telco cloud is a cloud environment where telecommunication services are hosted utilising NFV techniques. As the use of telecommunication standards moves towards 5G, network services will be provided in a virtualised manner in order to keep up with the demand. Open source software is a driver for innovation as it is has a collaborative culture to support it. This research investigates the readiness of open source tools to build a telco cloud that supports functions such as autoscaling and fault tolerance. Currently available open source software was explored for the different aspects involved in building a cloud from the ground up. The ETSI NFV MANO framework is also discussed as it is a widely used guiding standard for implementing NFV. Guided by the ETSI NFV MANO framework, open source software was used in an experiment to build a resilient cloud environment in which a virtualised IP Multimedia Subsystem (vIMS) network was deployed. Through this experimentation, it is evident that open source tools are mature enough to build the cloud environment and its ETSI NFV MANO compliant orchestration. However, features such as autoscaling and fault tolerance are still fairly immature and experimental.
- Full Text:
- Date Issued: 2020
A critical analysis of the South African turnover tax system
- Authors: Chiromo, Samuel John
- Date: 2020
- Subjects: Small business -- Taxation -- South Africa , Small business -- South Africa -- Finance , Turnover tax -- South Africa , Government aid to small business -- South Africa , Tax incentives -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/166103 , vital:41329
- Description: The objective of the turnover tax system is to reduce the administrative burden on micro businesses and to contribute positively to boosting these businesses and the economic growth of South Africa. The over-arching goal of this research was to analyse the South African turnover tax to investigate to what extent the turnover tax system complies with generally accepted principles of a good tax system. The research was conducted within an interpretative post-positivism paradigm, applied a qualitative research methodology, and a doctrinal research method. A detailed review of the literature was conducted to establish the nature of South African turnover tax system and the extent of its compliance with generally accepted principles of a good tax system. The literature review included an in-depth analysis of the South African turnover tax system, an in-depth analysis of generally accepted principles of a good tax system, and an investigation of the extent to which turnover tax system complies with various elements of the principles of a good tax system. It was found in this study that the turnover tax system does not comply with certain of the elements of generally accepted principles of a good tax system and the study proposed several recommendations for the improvement of the turnover tax system. These recommendations include the establishment of training initiatives for micro business owners, reviewing the regulations pertaining to turnover tax and providing digital administration of turnover tax.
- Full Text:
- Date Issued: 2020
- Authors: Chiromo, Samuel John
- Date: 2020
- Subjects: Small business -- Taxation -- South Africa , Small business -- South Africa -- Finance , Turnover tax -- South Africa , Government aid to small business -- South Africa , Tax incentives -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/166103 , vital:41329
- Description: The objective of the turnover tax system is to reduce the administrative burden on micro businesses and to contribute positively to boosting these businesses and the economic growth of South Africa. The over-arching goal of this research was to analyse the South African turnover tax to investigate to what extent the turnover tax system complies with generally accepted principles of a good tax system. The research was conducted within an interpretative post-positivism paradigm, applied a qualitative research methodology, and a doctrinal research method. A detailed review of the literature was conducted to establish the nature of South African turnover tax system and the extent of its compliance with generally accepted principles of a good tax system. The literature review included an in-depth analysis of the South African turnover tax system, an in-depth analysis of generally accepted principles of a good tax system, and an investigation of the extent to which turnover tax system complies with various elements of the principles of a good tax system. It was found in this study that the turnover tax system does not comply with certain of the elements of generally accepted principles of a good tax system and the study proposed several recommendations for the improvement of the turnover tax system. These recommendations include the establishment of training initiatives for micro business owners, reviewing the regulations pertaining to turnover tax and providing digital administration of turnover tax.
- Full Text:
- Date Issued: 2020
A gendered analysis of conditional cash based transfers: a case study of Puntland Technical Vocational Skills Training Programme, Somalia
- Authors: Chitombi, Rumbidzai
- Date: 2020
- Subjects: Puntland Technical Vocational Skills Training Programme , Transfer payments -- Somalia -- Case studies , Economic assistance, Domestic -- Somalia , Economic development -- Social aspects -- Somalia , Women -- Somalia -- Social conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167335 , vital:41469
- Description: As part of the worldwide development system, conditional cash transfer (CCT) programmes have become an increasingly popular policy and development approach in seeking to address poverty, especially in developing countries. Under the CCT programmes, beneficiaries are given assistance in the form of either cash or cash vouchers after fulfilling certain obligations of the development programme, such as attending training, enacting proper health care, or ensuring regular school attendance of children. The programmes have been described as a ‘double-edged sword’ since they aim to address poverty and, at the same time, reduce reliance on government largesse. In this regard, they are seen as potentially effective, and more empowering, alternatives to more traditional social assistance programmes whereby poor people receive welfare assistance in the form of ‘in kind’ and ‘unconditional’ assistance, receiving this as either food or shelter commodities, and without having to meet any conditions in doing so. This ‘traditional’ way of assisting poor people has largely been criticised for creating a dependency syndrome amongst the beneficiaries. In certain cases, CCT programmes focus specifically on women, either in receiving the cash transfer or in meeting the conditions attached to the programme, or both. In this context, considerable debate exists in the scholarly literature about the effects of such CCT programmes on the situation and status of women, specifically in terms of possibly empowering women. While some scholars claim that these programmes enhance the human and financial assets of women, others argue that focusing specifically on women, and as care-givers within households, tends to reproduce gender-based inequalities and subordination. Since gender equality and female empowerment are now key issues in global development spheres, and at national levels, this thesis aims to contribute to literature on the effects of CCTs on gender and women’s empowerment. This is pursued by way of a gendered perspective on CCTs as a development methodology for empowering women with reference to Somalia, using the Puntland Technical Vocational Skills Training programme as a case study. This programme focused, in the main, on internally-displaced people in Somalia, with a particular emphasis on women in meeting the programme conditions (i.e. participating in a training programme) and in being the cash recipients. The study used both quantitative and qualitative approaches for data collection and analysis, focusing on sixty selected beneficiaries who participated in the Puntland Technical Vocational skills training programme in Somalia from 2013. The thesis examines the prevailing structures (including cultural dynamics and socio-economic factors) in Somalia which lead to women’s subordination, notably in the light of significant internal displacement because of war and conflict and the emergence of internally-displaced camps. On this basis, from a gendered perspective, there is a critical appraisal of the manner in which the Puntland CCT programme affected women’s subordinate status, including how it may have led to the restructuring of gendered relations at both household and community levels. In offering this appraisal with reference to the Puntland programme, the thesis argues that women’s subordination and, by extension, women’s empowerment, is multi-faceted, and that continuity and change along the dimensions of subordination is often uneven and contradictory. Further, as also demonstrated in the Puntland case study, women’s subordination (as a social totality) is not a totalising system, such that women regularly make use of gaps in the system as opportunities to enhance their well-being without confronting the totality of the system.
- Full Text:
- Date Issued: 2020
- Authors: Chitombi, Rumbidzai
- Date: 2020
- Subjects: Puntland Technical Vocational Skills Training Programme , Transfer payments -- Somalia -- Case studies , Economic assistance, Domestic -- Somalia , Economic development -- Social aspects -- Somalia , Women -- Somalia -- Social conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167335 , vital:41469
- Description: As part of the worldwide development system, conditional cash transfer (CCT) programmes have become an increasingly popular policy and development approach in seeking to address poverty, especially in developing countries. Under the CCT programmes, beneficiaries are given assistance in the form of either cash or cash vouchers after fulfilling certain obligations of the development programme, such as attending training, enacting proper health care, or ensuring regular school attendance of children. The programmes have been described as a ‘double-edged sword’ since they aim to address poverty and, at the same time, reduce reliance on government largesse. In this regard, they are seen as potentially effective, and more empowering, alternatives to more traditional social assistance programmes whereby poor people receive welfare assistance in the form of ‘in kind’ and ‘unconditional’ assistance, receiving this as either food or shelter commodities, and without having to meet any conditions in doing so. This ‘traditional’ way of assisting poor people has largely been criticised for creating a dependency syndrome amongst the beneficiaries. In certain cases, CCT programmes focus specifically on women, either in receiving the cash transfer or in meeting the conditions attached to the programme, or both. In this context, considerable debate exists in the scholarly literature about the effects of such CCT programmes on the situation and status of women, specifically in terms of possibly empowering women. While some scholars claim that these programmes enhance the human and financial assets of women, others argue that focusing specifically on women, and as care-givers within households, tends to reproduce gender-based inequalities and subordination. Since gender equality and female empowerment are now key issues in global development spheres, and at national levels, this thesis aims to contribute to literature on the effects of CCTs on gender and women’s empowerment. This is pursued by way of a gendered perspective on CCTs as a development methodology for empowering women with reference to Somalia, using the Puntland Technical Vocational Skills Training programme as a case study. This programme focused, in the main, on internally-displaced people in Somalia, with a particular emphasis on women in meeting the programme conditions (i.e. participating in a training programme) and in being the cash recipients. The study used both quantitative and qualitative approaches for data collection and analysis, focusing on sixty selected beneficiaries who participated in the Puntland Technical Vocational skills training programme in Somalia from 2013. The thesis examines the prevailing structures (including cultural dynamics and socio-economic factors) in Somalia which lead to women’s subordination, notably in the light of significant internal displacement because of war and conflict and the emergence of internally-displaced camps. On this basis, from a gendered perspective, there is a critical appraisal of the manner in which the Puntland CCT programme affected women’s subordinate status, including how it may have led to the restructuring of gendered relations at both household and community levels. In offering this appraisal with reference to the Puntland programme, the thesis argues that women’s subordination and, by extension, women’s empowerment, is multi-faceted, and that continuity and change along the dimensions of subordination is often uneven and contradictory. Further, as also demonstrated in the Puntland case study, women’s subordination (as a social totality) is not a totalising system, such that women regularly make use of gaps in the system as opportunities to enhance their well-being without confronting the totality of the system.
- Full Text:
- Date Issued: 2020
The value of economic capital as an indicator to protect prospective and existing ordinary shareholders
- Authors: Chonzi, Tendai Day
- Date: 2020
- Subjects: Banks and banking -- Risk management -- South Africa , Financial services industry -- Risk management -- South Africa , ABSA Bank , FirstRand Limited , Nedbank , Standard Bank Limited , Capitec Bank (South Africa)
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/145807 , vital:38468
- Description: South Africans banking sector is one of the most dominating banking sectors in Africa. The banking sector is privately owned and involves a lot of different stakeholders, who risk losing their investments. One of the stakeholders who are the bottom of the repayment chain are existing ordinary shareholders because they risk losing all their investment in the result of bankruptcy, liquidity crises or the inability of the bank to repay their shareholders. Regulators in the banking sector only protect the depositor and the stability of the banking sector but not ordinary shareholders. An internal supervisory measure called economic capital has recently received more attention because of its aim to protect ordinary shareholders and thus, existing and prospective shareholders can use its value as a protective indicator. Economic theory assumes that the higher the value of economic capital (the lower the economic capital shortfall), the lower the return on investment for existing ordinary shareholders. The aforementioned shows a trade-off between protection (economic capital) and returns. Literature by Larsson (2009) further suggests that banks are always reluctant with implementing internal measures to protect themselves because of the good regulatory regime in the sector, some banks think that they are “too big to fail” and the fact that the reserve banks are always on the standby as a bailout. The purpose of this research is to examine which of the top five commercial banks in South African actively protect their existing ordinary shareholders using the value of economic capital and possibly attract prospective ordinary shareholders, locally and internationally. The banks under study are Absa, Capitec, FirstRand, Nedbank and Standard Bank over ten years, starting from June 2009 to May 2019 and in monthly frequency. The observations totalled 120 and two models that are under the Return Series Method were in used, namely; Historical Simulation Model and Variance Covariance Model. Both models, although they were small deviations in the value of economic capital, concluded that Standard Bank protects its existing ordinary shareholders the most, followed by FirstRand, then Absa and last is Nedbank. Capitec was the only bank, after one financial shock that could not protect its existing ordinary shareholders. Moreover, evidence in the study shows a trade-off between economic capital and return on investment in the case of Capitec and Standard Bank. Standard Bank had the highest value of economic capital and second-lowest return on investment, while Capitec had the highest return on investment and lowest value of economic capital. The significant policy implication of the research is that financial institution needs to strike a balance between protection and profits; thus, a way of protecting various stakeholders. Financial shocks have proven that regulatory measures are weak and they are is need for internal measures (economic capital) which indicate how financial institution can sustain in such cases.
- Full Text:
- Date Issued: 2020
- Authors: Chonzi, Tendai Day
- Date: 2020
- Subjects: Banks and banking -- Risk management -- South Africa , Financial services industry -- Risk management -- South Africa , ABSA Bank , FirstRand Limited , Nedbank , Standard Bank Limited , Capitec Bank (South Africa)
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/145807 , vital:38468
- Description: South Africans banking sector is one of the most dominating banking sectors in Africa. The banking sector is privately owned and involves a lot of different stakeholders, who risk losing their investments. One of the stakeholders who are the bottom of the repayment chain are existing ordinary shareholders because they risk losing all their investment in the result of bankruptcy, liquidity crises or the inability of the bank to repay their shareholders. Regulators in the banking sector only protect the depositor and the stability of the banking sector but not ordinary shareholders. An internal supervisory measure called economic capital has recently received more attention because of its aim to protect ordinary shareholders and thus, existing and prospective shareholders can use its value as a protective indicator. Economic theory assumes that the higher the value of economic capital (the lower the economic capital shortfall), the lower the return on investment for existing ordinary shareholders. The aforementioned shows a trade-off between protection (economic capital) and returns. Literature by Larsson (2009) further suggests that banks are always reluctant with implementing internal measures to protect themselves because of the good regulatory regime in the sector, some banks think that they are “too big to fail” and the fact that the reserve banks are always on the standby as a bailout. The purpose of this research is to examine which of the top five commercial banks in South African actively protect their existing ordinary shareholders using the value of economic capital and possibly attract prospective ordinary shareholders, locally and internationally. The banks under study are Absa, Capitec, FirstRand, Nedbank and Standard Bank over ten years, starting from June 2009 to May 2019 and in monthly frequency. The observations totalled 120 and two models that are under the Return Series Method were in used, namely; Historical Simulation Model and Variance Covariance Model. Both models, although they were small deviations in the value of economic capital, concluded that Standard Bank protects its existing ordinary shareholders the most, followed by FirstRand, then Absa and last is Nedbank. Capitec was the only bank, after one financial shock that could not protect its existing ordinary shareholders. Moreover, evidence in the study shows a trade-off between economic capital and return on investment in the case of Capitec and Standard Bank. Standard Bank had the highest value of economic capital and second-lowest return on investment, while Capitec had the highest return on investment and lowest value of economic capital. The significant policy implication of the research is that financial institution needs to strike a balance between protection and profits; thus, a way of protecting various stakeholders. Financial shocks have proven that regulatory measures are weak and they are is need for internal measures (economic capital) which indicate how financial institution can sustain in such cases.
- 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
The relevance of industrial/organisational psychology research in “post” colonial/apartheid South Africa : exploring the views of academics
- Authors: Christison, Michael Alan
- Date: 2020
- Subjects: Psychology, Industrial -- Research -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140331 , vital:37880
- Description: This dissertation explored the views of academics who teach and research in the area of Industrial/Organisational Psychology in South Africa about the utility of the field in engaging with the post-1994 South African workplace, thereby remaining relevant. When it emerged as a field of study and practice, Industrial/Organisational Psychology research’s aim was to inform workplace practice and contribute to the betterment of society. It appears as if today this research is deemed irrelevant to the workplace and society, with many practitioners relying on their own knowledge and irrelevant repetitive one size-fit-all Euro-American developed theoretical framework and research evidence to solve the challenges of the post-1994 South African workplace, and to serve its society. The latter propelled the researcher to ask broadly the question of relevancy of the discipline in meeting the demands of the post-1994 South African workplace. Face-to-face, semi-structured interviews were employed to collect data on 8 senior and younger generations of academics in 3 different universities. The collected data was analysed using Braun and Clarke’s 6 steps of thematic analysis. The data and study as a whole was approached with a ‘post’-colonial lens and a Contexualist paradigm in order to contextualise in the present time the past nuances that arose in our country during the colonial and apartheid eras. Themes discussed seemed to indicate a lack of research focus by academics and their students due to limited time and stringent bureaucratic publication structures present both within their universities and outside. When it came to the discipline as seen through the lens of the data and what this suggested in terms of speaking to post-1994 workplace organisational psychological problems, the study found that the findings arising out of the research in I/O psychology appear to be of little relevance to whom they are currently aimed, leading to the idea of these studies acting as a change agent in the workplace and society to fall to the wayside.
- Full Text:
- Date Issued: 2020
- Authors: Christison, Michael Alan
- Date: 2020
- Subjects: Psychology, Industrial -- Research -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/140331 , vital:37880
- Description: This dissertation explored the views of academics who teach and research in the area of Industrial/Organisational Psychology in South Africa about the utility of the field in engaging with the post-1994 South African workplace, thereby remaining relevant. When it emerged as a field of study and practice, Industrial/Organisational Psychology research’s aim was to inform workplace practice and contribute to the betterment of society. It appears as if today this research is deemed irrelevant to the workplace and society, with many practitioners relying on their own knowledge and irrelevant repetitive one size-fit-all Euro-American developed theoretical framework and research evidence to solve the challenges of the post-1994 South African workplace, and to serve its society. The latter propelled the researcher to ask broadly the question of relevancy of the discipline in meeting the demands of the post-1994 South African workplace. Face-to-face, semi-structured interviews were employed to collect data on 8 senior and younger generations of academics in 3 different universities. The collected data was analysed using Braun and Clarke’s 6 steps of thematic analysis. The data and study as a whole was approached with a ‘post’-colonial lens and a Contexualist paradigm in order to contextualise in the present time the past nuances that arose in our country during the colonial and apartheid eras. Themes discussed seemed to indicate a lack of research focus by academics and their students due to limited time and stringent bureaucratic publication structures present both within their universities and outside. When it came to the discipline as seen through the lens of the data and what this suggested in terms of speaking to post-1994 workplace organisational psychological problems, the study found that the findings arising out of the research in I/O psychology appear to be of little relevance to whom they are currently aimed, leading to the idea of these studies acting as a change agent in the workplace and society to fall to the wayside.
- Full Text:
- Date Issued: 2020
A study of why some physic concepts in the South African Physical Science curriculum are poorly understood in order to develop a targeted action-research intervention for Newton’s second law
- Authors: Cobbing, Kathleen Margaret
- Date: 2020
- Subjects: Physics -- Study and teaching (Secondary) -- South Africa , Physics -- Examinations, questions, etc. -- South Africa , Motion -- Study and teaching (Secondary) -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146903 , vital:38575
- Description: Globally, many students show a poor understanding of concepts in high school physics and lack the necessary problem-solving skills that the course demands. The application of Newton’s second law was found to be particularly problematic through document analysis of South African examination feedback reports, as well as from an analysis of the physics examinations at a pair of well-resourced South African independent schools that follow the Independent Examination Board curriculum. Through an action-research approach, a resource for use by students was designed and modified to improve students’ understanding of this concept, while modelling problemsolving methods. The resource consisted of brief revision notes, worked examples and scaffolded exercises. The design of the resource was influenced by the theory of cognitive apprenticeship, cognitive load theory and conceptual change theory. One of the aims of the resource was to encourage students to translate between the different representations of a problem situation: symbolic, abstract, model and concrete. The impact of this resource was evaluated at a pair of schools using a mixed methods approach. This incorporated pre- and post-tests for a quantitative assessment, qualitative student evaluations and the analysis of examination scripts. There was an improvement from pre- to post-test for all four iterations of the intervention and these improvements were shown to be significant. The use of the resource led to an increase in the quality and quantity of diagrams drawn by students in subsequent assessments.
- Full Text:
- Date Issued: 2020
- Authors: Cobbing, Kathleen Margaret
- Date: 2020
- Subjects: Physics -- Study and teaching (Secondary) -- South Africa , Physics -- Examinations, questions, etc. -- South Africa , Motion -- Study and teaching (Secondary) -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146903 , vital:38575
- Description: Globally, many students show a poor understanding of concepts in high school physics and lack the necessary problem-solving skills that the course demands. The application of Newton’s second law was found to be particularly problematic through document analysis of South African examination feedback reports, as well as from an analysis of the physics examinations at a pair of well-resourced South African independent schools that follow the Independent Examination Board curriculum. Through an action-research approach, a resource for use by students was designed and modified to improve students’ understanding of this concept, while modelling problemsolving methods. The resource consisted of brief revision notes, worked examples and scaffolded exercises. The design of the resource was influenced by the theory of cognitive apprenticeship, cognitive load theory and conceptual change theory. One of the aims of the resource was to encourage students to translate between the different representations of a problem situation: symbolic, abstract, model and concrete. The impact of this resource was evaluated at a pair of schools using a mixed methods approach. This incorporated pre- and post-tests for a quantitative assessment, qualitative student evaluations and the analysis of examination scripts. There was an improvement from pre- to post-test for all four iterations of the intervention and these improvements were shown to be significant. The use of the resource led to an increase in the quality and quantity of diagrams drawn by students in subsequent assessments.
- Full Text:
- Date Issued: 2020
Carnivore intra-guild competition in Selati Game Reserve, Limpopo Province, South Africa
- Authors: Comley, Jessica
- Date: 2020
- Subjects: Hyenas -- Behavior -- South Africa , Hyenas -- South Africa , Hyenas -- Ecology -- South Africa , Top predators -- South Africa , Top predators -- Ecology -- South Africa , Animal communities -- South Africa , Animal behavior -- South Africa , Mutualism (Biology) -- South Africa , Coexistence of species -- South Africa , Game farms -- South Africa , Selati Game Reserve (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115558 , vital:34163
- Description: Carnivore intra-guild interactions can be important drivers of carnivore community composition and ecosystem functioning. Large carnivores are particularly important since they occupy the highest trophic levels and can exert extensive influences on subordinate carnivores and prey species. Given Africa’s rapidly expanding human population, enclosed reserves such as those found in South Africa, may become increasingly important for carnivore conservation. A major concern, however, is that the interactions and co-existence of multiple carnivores in these systems is poorly understood. Additionally, the majority of reserves in South Africa are small ( 400km²), potentially increasing the likelihood of competition. My research aimed to provide insight into the interactions and co-existence of a multi-carnivore community within a small, enclosed reserve in South Africa (Selati Game Reserve). I tackled this task by using a combination of field techniques including camera trap surveys, ungulate transect surveys, aerial count surveys, location data collected from collared large carnivores and scat and kill site analyses. I found that carnivore-carnivore interactions, and their associated impacts, varied within the carnivore guild and that co-existence may be due to trade-offs between various risks (i.e. interference and exploitative competition) and benefits (i.e. resources such as food and space). My findings also revealed that large carnivores, such as lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus) do not have homogenous effects and that site-specific research on multiple-carnivores is integral for conserving biodiversity and ecosystem dynamics. Lions were the dominant large carnivore (in terms of intra-guild predation, space use and resource use) despite being outnumbered seven to one by spotted hyaenas. Leopard occupancy was negatively influenced by lions and leopard diet overlapped almost completely (91%) with spotted hyaenas, suggesting increased kleptoparasitism of leopard kills by spotted hyaenas. While my study provides valuable insight into the complexity of carnivore intra-guild competition in a small, enclosed reserve it also highlights major research gaps and emphasises the need for ecosystem-based research throughout southern Africa to fully understand how multiple sympatric carnivores co-exist in these systems.
- Full Text:
- Date Issued: 2020
- Authors: Comley, Jessica
- Date: 2020
- Subjects: Hyenas -- Behavior -- South Africa , Hyenas -- South Africa , Hyenas -- Ecology -- South Africa , Top predators -- South Africa , Top predators -- Ecology -- South Africa , Animal communities -- South Africa , Animal behavior -- South Africa , Mutualism (Biology) -- South Africa , Coexistence of species -- South Africa , Game farms -- South Africa , Selati Game Reserve (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115558 , vital:34163
- Description: Carnivore intra-guild interactions can be important drivers of carnivore community composition and ecosystem functioning. Large carnivores are particularly important since they occupy the highest trophic levels and can exert extensive influences on subordinate carnivores and prey species. Given Africa’s rapidly expanding human population, enclosed reserves such as those found in South Africa, may become increasingly important for carnivore conservation. A major concern, however, is that the interactions and co-existence of multiple carnivores in these systems is poorly understood. Additionally, the majority of reserves in South Africa are small ( 400km²), potentially increasing the likelihood of competition. My research aimed to provide insight into the interactions and co-existence of a multi-carnivore community within a small, enclosed reserve in South Africa (Selati Game Reserve). I tackled this task by using a combination of field techniques including camera trap surveys, ungulate transect surveys, aerial count surveys, location data collected from collared large carnivores and scat and kill site analyses. I found that carnivore-carnivore interactions, and their associated impacts, varied within the carnivore guild and that co-existence may be due to trade-offs between various risks (i.e. interference and exploitative competition) and benefits (i.e. resources such as food and space). My findings also revealed that large carnivores, such as lions (Panthera leo), spotted hyaenas (Crocuta crocuta) and leopards (Panthera pardus) do not have homogenous effects and that site-specific research on multiple-carnivores is integral for conserving biodiversity and ecosystem dynamics. Lions were the dominant large carnivore (in terms of intra-guild predation, space use and resource use) despite being outnumbered seven to one by spotted hyaenas. Leopard occupancy was negatively influenced by lions and leopard diet overlapped almost completely (91%) with spotted hyaenas, suggesting increased kleptoparasitism of leopard kills by spotted hyaenas. While my study provides valuable insight into the complexity of carnivore intra-guild competition in a small, enclosed reserve it also highlights major research gaps and emphasises the need for ecosystem-based research throughout southern Africa to fully understand how multiple sympatric carnivores co-exist in these systems.
- Full Text:
- Date Issued: 2020
Long Waves of Strikes in South Africa: 1886–2019
- Authors: Cottle, Eddie
- Date: 2020
- Subjects: Strikes and lockouts South Africa , Long waves (Economics) South Africa , Business cycles South Africa , Industrial mobilization South Africa , Collective bargaining South Africa , Institutionalisation , Labor unions South Africa
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163228 , vital:41020 , doi:10.21504/10962/163228
- Description: Thesis (PhD)--Rhodes University, Faculty of Humanities, Institute for Social and Economic Research (ISER), 2020.
- Full Text:
- Date Issued: 2020
- Authors: Cottle, Eddie
- Date: 2020
- Subjects: Strikes and lockouts South Africa , Long waves (Economics) South Africa , Business cycles South Africa , Industrial mobilization South Africa , Collective bargaining South Africa , Institutionalisation , Labor unions South Africa
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163228 , vital:41020 , doi:10.21504/10962/163228
- Description: Thesis (PhD)--Rhodes University, Faculty of Humanities, Institute for Social and Economic Research (ISER), 2020.
- Full Text:
- Date Issued: 2020
‘This sea of darkness, craziness and opportunity’: students experiences of depression and social identities at a South African university
- Authors: Craig, Ashleigh
- Date: 2020
- Subjects: Depression, Mental -- South Africa -- Makhanda , Depression in adolescence -- South Africa -- Makhanda , College students -- Mental health -- South Africa -- Makhanda , Group identity -- South Africa -- Makhanda , Phenomenological psychology , Education, Higher -- Social aspects -- South Africa , Rhodes University
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/118632 , vital:34655
- Description: This study explores how the interaction between depression and social identities is experienced by South African university students. Semi-structured interviews were conducted with eight students at Rhodes University who have had depressive experiences and analysed using Interpretative Phenomenological Analysis. The following five superordinate themes emerged out of the data: 1) the self looking in, 2) the self looking out, 3) the misunderstood self, 4) the student self and 5) the loss of self. Findings showed that students’ depression is significantly influenced by their social identities, which are experienced as multi-faceted and ever-changing within the university context. The related therapeutic implications are also discussed.
- Full Text:
- Date Issued: 2020
- Authors: Craig, Ashleigh
- Date: 2020
- Subjects: Depression, Mental -- South Africa -- Makhanda , Depression in adolescence -- South Africa -- Makhanda , College students -- Mental health -- South Africa -- Makhanda , Group identity -- South Africa -- Makhanda , Phenomenological psychology , Education, Higher -- Social aspects -- South Africa , Rhodes University
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/118632 , vital:34655
- Description: This study explores how the interaction between depression and social identities is experienced by South African university students. Semi-structured interviews were conducted with eight students at Rhodes University who have had depressive experiences and analysed using Interpretative Phenomenological Analysis. The following five superordinate themes emerged out of the data: 1) the self looking in, 2) the self looking out, 3) the misunderstood self, 4) the student self and 5) the loss of self. Findings showed that students’ depression is significantly influenced by their social identities, which are experienced as multi-faceted and ever-changing within the university context. The related therapeutic implications are also discussed.
- Full Text:
- Date Issued: 2020
A comparative study of the tax measures for persons with disabilities in South Africa with those of Canada and the Republic of Ireland
- Authors: Currie, Natasha
- Date: 2020
- Subjects: People with disabilities -- Taxation -- South Africa , People with disabilities -- Taxation -- Law and legislation -- South Africa , People with disabilities -- Taxation -- Canada , People with disabilities -- Taxation -- Law and legislation -- Ireland , People with disabilities -- Taxation -- Ireland
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/170746 , vital:41956
- Description: Literature indicates that tax relief measures for persons with disabilities are important as they align with the principle of equity in the allocation of the tax burden. They are a government intervention that assists in decreasing the financial burden of medical care for persons with disabilities. The right of persons with disabilities to an adequate standard of living is contained in the landmark Convention on the Rights of Persons with Disabilities and Optional Protocol, a treaty of the United Nations, which South Africa ratified in 2007. The objective of the research was to provide a comparative study of tax relief measures for persons with disabilities in South Africa with those of Canada and the Republic of Ireland, with a view to identifying potential areas for improvement in South Africa. The requisite information was primarily collected through an extensive analysis of the tax legislation in the jurisdictions. The research found that tax relief measures for persons with disabilities and their families in South Africa are limited when compared with those of Canada and the Republic of Ireland. The comparative study identifies a number of potential tax relief measures for implementation in South Africa.
- Full Text:
- Date Issued: 2020
- Authors: Currie, Natasha
- Date: 2020
- Subjects: People with disabilities -- Taxation -- South Africa , People with disabilities -- Taxation -- Law and legislation -- South Africa , People with disabilities -- Taxation -- Canada , People with disabilities -- Taxation -- Law and legislation -- Ireland , People with disabilities -- Taxation -- Ireland
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/170746 , vital:41956
- Description: Literature indicates that tax relief measures for persons with disabilities are important as they align with the principle of equity in the allocation of the tax burden. They are a government intervention that assists in decreasing the financial burden of medical care for persons with disabilities. The right of persons with disabilities to an adequate standard of living is contained in the landmark Convention on the Rights of Persons with Disabilities and Optional Protocol, a treaty of the United Nations, which South Africa ratified in 2007. The objective of the research was to provide a comparative study of tax relief measures for persons with disabilities in South Africa with those of Canada and the Republic of Ireland, with a view to identifying potential areas for improvement in South Africa. The requisite information was primarily collected through an extensive analysis of the tax legislation in the jurisdictions. The research found that tax relief measures for persons with disabilities and their families in South Africa are limited when compared with those of Canada and the Republic of Ireland. The comparative study identifies a number of potential tax relief measures for implementation in South Africa.
- Full Text:
- Date Issued: 2020
Use of eco-art education in supporting the establishment of sustainability competencies in basic education: an interventionist case study
- Authors: Da Silva, Juliana Schmidt
- Date: 2020
- Subjects: Environment (Art) , Environmental education -- Brazil , Sustainable development -- Brazil , Education -- Curricula -- Brazil , Eco-art education
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/166127 , vital:41331
- Description: Recent socioecological approaches in Environmental Education acknowledge the complexity of “real-world situations”, which include environmental problems. One response to the challenge of enabling people to develop sustainability is the key competencies in sustainability framework. It can be faced as a guide to planning Environmental Education actions. On the other side, art practices hold potential to expand learning in varied ways. Art can offer the strategies employed in learning processes directed to sustainability, constituting the field of eco-art education. This research aims to investigate the integration of the visions of the key competencies in sustainability and the eco-art education in an Environmental Education project at high school level. Horta and Gastronomia (Vegetable Garden and Gastronomy) is an extra-curricular activity which happens every year at Irmão Jaime Biazus high school in Porto Alegre, Brazil. It addresses food security and sustainability associating the garden, the kitchen and exploration of sustainability issues using eco-art strategies. Action research approach is used, defining two research cycles to explore the effectiveness of eco-art for the development of key competencies in sustainability. The first cycle focuses on the eco-art activities applied in Horta and Gastronomia (2017 group) while the second cycle deals with a post-project intervention designed to observe indicators of the sustainability competencies and further explore eco-art strategies. This study adds to the field of sustainability competencies by exploring teaching strategies through eco-art education. Insight into key competencies in sustainability is given by presenting the investigation of the group of students about a situation of their reality. The activities implemented, classified according to their objectives, are contextualized regarding the competencies and in learning sequences. This research also contributes to the development of the sustainability competencies framework by applying the theory to a basic education level, adapting the work originally proposed to higher education contexts.
- Full Text:
- Date Issued: 2020
- Authors: Da Silva, Juliana Schmidt
- Date: 2020
- Subjects: Environment (Art) , Environmental education -- Brazil , Sustainable development -- Brazil , Education -- Curricula -- Brazil , Eco-art education
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/166127 , vital:41331
- Description: Recent socioecological approaches in Environmental Education acknowledge the complexity of “real-world situations”, which include environmental problems. One response to the challenge of enabling people to develop sustainability is the key competencies in sustainability framework. It can be faced as a guide to planning Environmental Education actions. On the other side, art practices hold potential to expand learning in varied ways. Art can offer the strategies employed in learning processes directed to sustainability, constituting the field of eco-art education. This research aims to investigate the integration of the visions of the key competencies in sustainability and the eco-art education in an Environmental Education project at high school level. Horta and Gastronomia (Vegetable Garden and Gastronomy) is an extra-curricular activity which happens every year at Irmão Jaime Biazus high school in Porto Alegre, Brazil. It addresses food security and sustainability associating the garden, the kitchen and exploration of sustainability issues using eco-art strategies. Action research approach is used, defining two research cycles to explore the effectiveness of eco-art for the development of key competencies in sustainability. The first cycle focuses on the eco-art activities applied in Horta and Gastronomia (2017 group) while the second cycle deals with a post-project intervention designed to observe indicators of the sustainability competencies and further explore eco-art strategies. This study adds to the field of sustainability competencies by exploring teaching strategies through eco-art education. Insight into key competencies in sustainability is given by presenting the investigation of the group of students about a situation of their reality. The activities implemented, classified according to their objectives, are contextualized regarding the competencies and in learning sequences. This research also contributes to the development of the sustainability competencies framework by applying the theory to a basic education level, adapting the work originally proposed to higher education contexts.
- Full Text:
- Date Issued: 2020
Unpacking the link between adaptive capacity, assets and responses of rural livelihoods facing multiple stressors in the Eastern Cape
- Dalu, Mwazvita Tapiwa Beatrice
- Authors: Dalu, Mwazvita Tapiwa Beatrice
- Date: 2020
- Language: English
- Type: thesis , text , Doctoral , Ph.D
- Identifier: http://hdl.handle.net/10962/147103 , vital:38593 , doi:10.21504/10962/147103
- Description: Thesis (PhD.)--Rhodes University, Faculty of Science, Environmental Science, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Dalu, Mwazvita Tapiwa Beatrice
- Date: 2020
- Language: English
- Type: thesis , text , Doctoral , Ph.D
- Identifier: http://hdl.handle.net/10962/147103 , vital:38593 , doi:10.21504/10962/147103
- Description: Thesis (PhD.)--Rhodes University, Faculty of Science, Environmental Science, 2020.
- Full Text:
- Date Issued: 2020
Water footprint and economic water productivity of citrus production: a comparison across three river valleys in the Eastern Cape Milands
- Authors: Danckwerts, Lindsay
- Date: 2020
- Subjects: Water in agriculture -- South Africa -- Eastern Cape , Water consumption -- South Africa -- Economic aspects , Water supply, Agricultural -- South Africa -- Eastern Cape , Citrus fruit industry -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/141064 , vital:37941
- Description: South Africa is a semi-arid, water scarce country. The nation has suffered a spate of severe droughts in several regions in recent years, which have significantly impacted the country’s economy. Global warming, population growth, and rising demand for water intensive products are only expected to intensify water supply problems in the future. The agricultural industry is the largest consumer of water in South Africa, accounting for the majority of total surface water withdrawals. As such, the agricultural sector is faced with complex and difficult management decisions in the face of a potential water supply crisis. The water footprint (WF) and economic water productivity (EWP) of citrus production across three river catchments located in the Eastern Cape Midlands (situated in the vicinity of the settlements of Adelaide, Cookhouse and Fort Beaufort respectively) were calculated and compared. In the long-term average (LTA), blue WF weighted across all three regions accounted for the greatest proportion of total WF (53%), followed in turn by green and grey WF (30% and 17% respectively). LTA blue and grey WF was lowest in the Adelaide region, while green WF was smallest in the Fort Beaufort region. Blue, green and grey WF were found to be greatest in the Cookhouse region. LTA EWP was greatest in the Fort Beaufort region and smallest in the Adelaide region. Of all variety groups assessed, lemons were found to have the lowest LTA crop water use and blue, green and grey WF when considering citrus production averaged across all three study regions. Satsumas has the second smallest LTA blue, green and grey WF, followed by navels, mid-season mandarins, and finally, late mandarins. Lemons had the greatest LTA EWP of all varieties, followed in turn by satsumas, late mandarins, mid-season mandarins and navels. Blue crop water use was consistently lowest in the designated wet year and highest in the dry year. However, this same trend was not necessarily true for WF findings. WF and EWP are useful indicators of water use which can be used to help guide complex water management decisions. However, these indicators are single-factor productivity measures applied in a multi-factor environment. It is therefore important that factors outside of water use are considered when making water management decisions. Moreover, it is important to examine the impact that the various components making up WF and EWP have on the resultant figures, rather than merely considering the superficial results themselves. Factors such as CWU, orchard maturity, crop choice, potential yield, climate, irrigation system, economic return, water allocation and water availability should all be taken into account.
- Full Text:
- Date Issued: 2020
- Authors: Danckwerts, Lindsay
- Date: 2020
- Subjects: Water in agriculture -- South Africa -- Eastern Cape , Water consumption -- South Africa -- Economic aspects , Water supply, Agricultural -- South Africa -- Eastern Cape , Citrus fruit industry -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/141064 , vital:37941
- Description: South Africa is a semi-arid, water scarce country. The nation has suffered a spate of severe droughts in several regions in recent years, which have significantly impacted the country’s economy. Global warming, population growth, and rising demand for water intensive products are only expected to intensify water supply problems in the future. The agricultural industry is the largest consumer of water in South Africa, accounting for the majority of total surface water withdrawals. As such, the agricultural sector is faced with complex and difficult management decisions in the face of a potential water supply crisis. The water footprint (WF) and economic water productivity (EWP) of citrus production across three river catchments located in the Eastern Cape Midlands (situated in the vicinity of the settlements of Adelaide, Cookhouse and Fort Beaufort respectively) were calculated and compared. In the long-term average (LTA), blue WF weighted across all three regions accounted for the greatest proportion of total WF (53%), followed in turn by green and grey WF (30% and 17% respectively). LTA blue and grey WF was lowest in the Adelaide region, while green WF was smallest in the Fort Beaufort region. Blue, green and grey WF were found to be greatest in the Cookhouse region. LTA EWP was greatest in the Fort Beaufort region and smallest in the Adelaide region. Of all variety groups assessed, lemons were found to have the lowest LTA crop water use and blue, green and grey WF when considering citrus production averaged across all three study regions. Satsumas has the second smallest LTA blue, green and grey WF, followed by navels, mid-season mandarins, and finally, late mandarins. Lemons had the greatest LTA EWP of all varieties, followed in turn by satsumas, late mandarins, mid-season mandarins and navels. Blue crop water use was consistently lowest in the designated wet year and highest in the dry year. However, this same trend was not necessarily true for WF findings. WF and EWP are useful indicators of water use which can be used to help guide complex water management decisions. However, these indicators are single-factor productivity measures applied in a multi-factor environment. It is therefore important that factors outside of water use are considered when making water management decisions. Moreover, it is important to examine the impact that the various components making up WF and EWP have on the resultant figures, rather than merely considering the superficial results themselves. Factors such as CWU, orchard maturity, crop choice, potential yield, climate, irrigation system, economic return, water allocation and water availability should all be taken into account.
- Full Text:
- Date Issued: 2020
Thermoluminescence and phototransferred phermoluminescence of synthetic quartz
- Authors: Dawam, Robert Rangmou
- Date: 2020
- Subjects: Thermoluminescence , Quartz
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145849 , vital:38472
- Description: The main aim of this investigation is on thermoluminescence and phototransferred thermoluminescence of synthetic quartz. Thermoluminescence was one of the tools used in characterising the electron traps parameters. The samples of quartz annealed at various temperatures up to 900̊C and the unannealed were used. The thermoluminescence glow curve was measured at 1̊C s~ 1 following beta irradiation to 40 Gy from the samples annealed at 500̊C and the unannealed consist of main peak at 70̊C and secondary peaks at 110, 180 and 310̊C. In comparison, the thermoluminescence glow curve for the sample annealed at 900̊C have main peak at 86̊C and the secondary ones at 170 and 310̊C. The kinetic analysis was carried out only on the main peak in each case. The activation energy was found to be decreasing with increase in annealing temperatures. The samples annealed at 500̊C and the unannealed were found to be affected by thermal quenching while sample annealed at 900̊C shows an inverse quenching for irradiation dose of 40 Gy. However, when the dose was reduce to 3 Gy the effects of thermal quenching was manifested. The activation energy of thermal quenching was also found to decrease with increase in annealing temperature. Thermally assisted optically stimulated luminescence measurement was carried out using continuous wave optical stimulated luminescence (CW-OSL). The samples studied were those annealed at 500̊C for 10 minutes, 900̊C for 10, 30, 60 minutes and 1000̊C for 10 minutes prior to use. The CW-OSL is stimulated using 470 nm blue LEDs at sample temperatures between 30 and 200̊C. It is measured after preheating to either 300 and 500̊C. When the integrated OSL intensity is plotted as a function of measurement temperature, the intensity goes through a peak. The increase in OSL intensity as a function of temperature is associated to thermal assistance and the decrease to thermal quenching. The kinetic parameters were evaluated by fitting the experimental data. The values of activation energies of thermal quenching are the same within experimental uncertainties for all the experimental conditions. This shows that annealing temperature, duration of annealing and irradiation dose have a negligible influence on the recombination site of luminescence using OSL. Phototransferred thermoluminescence (PTTL) induced from annealed samples using 470 nm blue light was also investigated. The quartz were annealed at 500 _C for 10 minutes, 900̊C for 10, 30, 60 minutes and 1000̊C for 10 minutes prior to use. The glow curves of conventional TL measured at 1 _C s1 following irradiation to 200 Gy shows six peaks in each case labelled I-VI for ease of reference whereas peaks observed under PTTL are referred to as A1 onwards. Only the first three peaks were reproduced under phototransfer for the sample annealed at 900̊C for 60 minutes and 1000̊C C for 10 minutes. Interestingly, for the intermediate duration of annealing of 30 minutes, the only peak that appears under phototransfer is the A1. For quartz annealed at 900̊C for 10 minutes, the PTTL appears as long as the preheating temperature does not exceed 560̊C. All other annealing temperatures, PTTL only appears for preheating to 450 and below. This shows that the occupancy of deep electron traps at temperatures beyond 450̊C or 560̊C is low. The activation energy for peaks A1, A2 and A3 were calculated. The PTTL peaks were studied for thermal quenching and peaks A1 and A3 were found to be affected. The activation energies for thermal quenching were determined as 0.62 ± 0.04 eV and 0.65 ± 0.02 eV for peaks A1 and A3 respectively. The experimental dependence of PTTL intensity on illumination time is modelled using sets of coupled linear differential equations based on systems of donors and acceptors whose number is determined by preheating temperature.
- Full Text:
- Date Issued: 2020
- Authors: Dawam, Robert Rangmou
- Date: 2020
- Subjects: Thermoluminescence , Quartz
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/145849 , vital:38472
- Description: The main aim of this investigation is on thermoluminescence and phototransferred thermoluminescence of synthetic quartz. Thermoluminescence was one of the tools used in characterising the electron traps parameters. The samples of quartz annealed at various temperatures up to 900̊C and the unannealed were used. The thermoluminescence glow curve was measured at 1̊C s~ 1 following beta irradiation to 40 Gy from the samples annealed at 500̊C and the unannealed consist of main peak at 70̊C and secondary peaks at 110, 180 and 310̊C. In comparison, the thermoluminescence glow curve for the sample annealed at 900̊C have main peak at 86̊C and the secondary ones at 170 and 310̊C. The kinetic analysis was carried out only on the main peak in each case. The activation energy was found to be decreasing with increase in annealing temperatures. The samples annealed at 500̊C and the unannealed were found to be affected by thermal quenching while sample annealed at 900̊C shows an inverse quenching for irradiation dose of 40 Gy. However, when the dose was reduce to 3 Gy the effects of thermal quenching was manifested. The activation energy of thermal quenching was also found to decrease with increase in annealing temperature. Thermally assisted optically stimulated luminescence measurement was carried out using continuous wave optical stimulated luminescence (CW-OSL). The samples studied were those annealed at 500̊C for 10 minutes, 900̊C for 10, 30, 60 minutes and 1000̊C for 10 minutes prior to use. The CW-OSL is stimulated using 470 nm blue LEDs at sample temperatures between 30 and 200̊C. It is measured after preheating to either 300 and 500̊C. When the integrated OSL intensity is plotted as a function of measurement temperature, the intensity goes through a peak. The increase in OSL intensity as a function of temperature is associated to thermal assistance and the decrease to thermal quenching. The kinetic parameters were evaluated by fitting the experimental data. The values of activation energies of thermal quenching are the same within experimental uncertainties for all the experimental conditions. This shows that annealing temperature, duration of annealing and irradiation dose have a negligible influence on the recombination site of luminescence using OSL. Phototransferred thermoluminescence (PTTL) induced from annealed samples using 470 nm blue light was also investigated. The quartz were annealed at 500 _C for 10 minutes, 900̊C for 10, 30, 60 minutes and 1000̊C for 10 minutes prior to use. The glow curves of conventional TL measured at 1 _C s1 following irradiation to 200 Gy shows six peaks in each case labelled I-VI for ease of reference whereas peaks observed under PTTL are referred to as A1 onwards. Only the first three peaks were reproduced under phototransfer for the sample annealed at 900̊C for 60 minutes and 1000̊C C for 10 minutes. Interestingly, for the intermediate duration of annealing of 30 minutes, the only peak that appears under phototransfer is the A1. For quartz annealed at 900̊C for 10 minutes, the PTTL appears as long as the preheating temperature does not exceed 560̊C. All other annealing temperatures, PTTL only appears for preheating to 450 and below. This shows that the occupancy of deep electron traps at temperatures beyond 450̊C or 560̊C is low. The activation energy for peaks A1, A2 and A3 were calculated. The PTTL peaks were studied for thermal quenching and peaks A1 and A3 were found to be affected. The activation energies for thermal quenching were determined as 0.62 ± 0.04 eV and 0.65 ± 0.02 eV for peaks A1 and A3 respectively. The experimental dependence of PTTL intensity on illumination time is modelled using sets of coupled linear differential equations based on systems of donors and acceptors whose number is determined by preheating temperature.
- Full Text:
- Date Issued: 2020