Academic readiness of students for higher education: a case for academic support at Rhodes University
- Authors: Khoza, Lebogang Peter
- Date: 2020
- Subjects: College student development programs -- South Africa -- Makhanda , Dropouts -- Prevention , College students -- South Africa-- Makhanda -- Social conditions , School failure -- South Africa -- Makhanda , Academic achievement-- South Africa -- Makhanda , Student adjustment -- South Africa -- Makhanda , Counseling in higher education -- South Africa -- Makhanda , Student Integration Model , Conceptual Framework Model , Geometric Design of Student Persistence
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/147848 , vital:38678
- Description: The worrying existence of incidences of student retention, poor pass rates and an increase in repetition rates is a cause for concern for institutions of higher learning in South Africa. The problem of student retention is not new in our institutions of higher learning. Support structures, strategies, and policies need to be developed for different academic and social challenges that students face daily. This study explores the need for academic support at Rhodes University; it also explores the internal and external problems that students face, the perceptions and experiences of students on academic support available to them. The study implemented a narrative research approach implanted within a qualitative research framework. Data was collected through a questionnaire, and narrative interviews. Tinto’s Student Integration Model was used to analyse the data in this study and was supplemented by Louw’s conceptual framework model and Swail’s Geometric Design of Student Persistence. These three models position the student experience as the foundation for academic support programmes and development. The study argues that as long as effective and adequate academic support is lacking, students will continue to experience difficulties in completing their studies. The findings from the study reveal that at present, Rhodes University provides support to students who are in extended studies. However, this support system disadvantages many students, notably those not in the extended studies programme. As a result, such students are not supported through strategies and structures that extended studies students receive. Furthermore, the data generates internal and external problems that student face daily, as a result, the findings showed that there is a need for academic support at Rhodes. The study recommends that Rhodes University must establish an academic unit that will provide academic support to all students registered in the university.
- Full Text:
- Date Issued: 2020
- Authors: Khoza, Lebogang Peter
- Date: 2020
- Subjects: College student development programs -- South Africa -- Makhanda , Dropouts -- Prevention , College students -- South Africa-- Makhanda -- Social conditions , School failure -- South Africa -- Makhanda , Academic achievement-- South Africa -- Makhanda , Student adjustment -- South Africa -- Makhanda , Counseling in higher education -- South Africa -- Makhanda , Student Integration Model , Conceptual Framework Model , Geometric Design of Student Persistence
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/147848 , vital:38678
- Description: The worrying existence of incidences of student retention, poor pass rates and an increase in repetition rates is a cause for concern for institutions of higher learning in South Africa. The problem of student retention is not new in our institutions of higher learning. Support structures, strategies, and policies need to be developed for different academic and social challenges that students face daily. This study explores the need for academic support at Rhodes University; it also explores the internal and external problems that students face, the perceptions and experiences of students on academic support available to them. The study implemented a narrative research approach implanted within a qualitative research framework. Data was collected through a questionnaire, and narrative interviews. Tinto’s Student Integration Model was used to analyse the data in this study and was supplemented by Louw’s conceptual framework model and Swail’s Geometric Design of Student Persistence. These three models position the student experience as the foundation for academic support programmes and development. The study argues that as long as effective and adequate academic support is lacking, students will continue to experience difficulties in completing their studies. The findings from the study reveal that at present, Rhodes University provides support to students who are in extended studies. However, this support system disadvantages many students, notably those not in the extended studies programme. As a result, such students are not supported through strategies and structures that extended studies students receive. Furthermore, the data generates internal and external problems that student face daily, as a result, the findings showed that there is a need for academic support at Rhodes. The study recommends that Rhodes University must establish an academic unit that will provide academic support to all students registered in the university.
- Full Text:
- Date Issued: 2020
Acceptance of ambulatory blood pressure monitoring in a semi-rural population in South Africa:
- Chiwanza, Farisai, Irwin, Yoland, Dowse, Roslind
- Authors: Chiwanza, Farisai , Irwin, Yoland , Dowse, Roslind
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157072 , vital:40084 , DOI: https://doi.org/10.4102/hsag.v25i0.1336
- Description: Ambulatory blood pressure monitoring is a valuable tool that helps in providing an insight into the diagnosis and management of hypertension; however, no evidence exists of its acceptance in the diverse South African population. We assessed the acceptance of an ambulatory blood pressure monitor in patients attending public sector primary health care (PHC) clinics. Five PHC clinics in the Makana subdistrict in the Eastern Cape.
- Full Text:
- Date Issued: 2020
- Authors: Chiwanza, Farisai , Irwin, Yoland , Dowse, Roslind
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157072 , vital:40084 , DOI: https://doi.org/10.4102/hsag.v25i0.1336
- Description: Ambulatory blood pressure monitoring is a valuable tool that helps in providing an insight into the diagnosis and management of hypertension; however, no evidence exists of its acceptance in the diverse South African population. We assessed the acceptance of an ambulatory blood pressure monitor in patients attending public sector primary health care (PHC) clinics. Five PHC clinics in the Makana subdistrict in the Eastern Cape.
- Full Text:
- Date Issued: 2020
Access to social grants information by the Balfour Village elderly population in Eastern Cape Province, South Africa
- Authors: Faku, Andile
- Date: 2020
- Subjects: Information services Information resources
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Library and Information Science)
- Identifier: http://hdl.handle.net/10353/18096 , vital:42231
- Description: This study sought to investigate the access to information about social grants by the elderly population of Balfour village in Raymond Mhlaba Local Municipality in SA’s Eastern Cape Province. A study on access to information is quite relevant in the knowledge-based economies. People act when they have information and similarly elderly people require information in order to access their grants. This study is quite relevant in the Library and Information Science field. The targeted population for the study were the elderly people of the Balfour village. The qualitative research approach was used in this study. The researcher selected a sample for the study using snowballsampling procedure. Both in-depth interviews and questionnaires were employed as methods of gathering data and thematic analysis of data was used. Results showed that there is a lack of information dissemination and access to information about social grants for elderly people living in Balfour. The study found out that elderly people in Balfour complained that, in most cases, they were not sure about the documents they were supposed to bring with them when they visited the South African Social Security Agency offices. This indicates the need for SASSA to train their staff members to be customer orientated and encourage staff to empower themselves with formal educational qualifications. In addition, the distance to and from SASSA offices is of great concern because elderly people spend significant amounts of money for travelling these distances. Therefore, there must be an office that is situated in a favourable distance to the elderly so that they do not struggle when they want to reach SASSA offices. Another option would be to avail a mobile office that may serve the area two or three times a week.
- Full Text:
- Date Issued: 2020
- Authors: Faku, Andile
- Date: 2020
- Subjects: Information services Information resources
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Library and Information Science)
- Identifier: http://hdl.handle.net/10353/18096 , vital:42231
- Description: This study sought to investigate the access to information about social grants by the elderly population of Balfour village in Raymond Mhlaba Local Municipality in SA’s Eastern Cape Province. A study on access to information is quite relevant in the knowledge-based economies. People act when they have information and similarly elderly people require information in order to access their grants. This study is quite relevant in the Library and Information Science field. The targeted population for the study were the elderly people of the Balfour village. The qualitative research approach was used in this study. The researcher selected a sample for the study using snowballsampling procedure. Both in-depth interviews and questionnaires were employed as methods of gathering data and thematic analysis of data was used. Results showed that there is a lack of information dissemination and access to information about social grants for elderly people living in Balfour. The study found out that elderly people in Balfour complained that, in most cases, they were not sure about the documents they were supposed to bring with them when they visited the South African Social Security Agency offices. This indicates the need for SASSA to train their staff members to be customer orientated and encourage staff to empower themselves with formal educational qualifications. In addition, the distance to and from SASSA offices is of great concern because elderly people spend significant amounts of money for travelling these distances. Therefore, there must be an office that is situated in a favourable distance to the elderly so that they do not struggle when they want to reach SASSA offices. Another option would be to avail a mobile office that may serve the area two or three times a week.
- Full Text:
- Date Issued: 2020
Accessibility of agricultural information by smallholder farmers in Amatole District Municipality: Nexus between agricultural extension services and the library
- Authors: Sigigaba, Masimthembe
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/18849 , vital:42870
- Description: Accessibility to relevant, accurate and timely information remains vital in farming. For farmers to improve their productivity they depend on access to pertinent agricultural information. Such information updated them about new agricultural technologies, climate change, new cultivars, access to market and access to financial assistance. These types of information help farmers in decision making regarding their farming. Agricultural extension officers remain a reliable source where farmers could obtain relevant agricultural information. Community libraries are also channels that could be used by agricultural extension officers to complement their work of providing farmers with information. Thus, the study sought to assess linkage between these two institutions to provide farmers with information. A positivism paradigm with quantitative research approach were adopted in the study. Smallholder farmers (169), agricultural extension officers (5) and librarians (15) were the unit of analysis. A semi-structured questionnaire was used for data collection and SPSS software for analysis. Findings revealed that, agricultural extension officers mostly utilise interpersonal channels that include demonstrations, group meetings and face-to-face interaction to provide farmers with information. Community libraries were found to be non-utilised by extension services and also by farmers. Farmers were of the perception that libraries are meant for educated people. It was also discovered that community libraries have information on agriculture that only targets learners who are taking agriculture in school as a subject. There was no existing linkage between agricultural extension services and community libraries working together to provide farmers with pertinent agricultural information that can help them improve productivity
- Full Text:
- Date Issued: 2020
- Authors: Sigigaba, Masimthembe
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/18849 , vital:42870
- Description: Accessibility to relevant, accurate and timely information remains vital in farming. For farmers to improve their productivity they depend on access to pertinent agricultural information. Such information updated them about new agricultural technologies, climate change, new cultivars, access to market and access to financial assistance. These types of information help farmers in decision making regarding their farming. Agricultural extension officers remain a reliable source where farmers could obtain relevant agricultural information. Community libraries are also channels that could be used by agricultural extension officers to complement their work of providing farmers with information. Thus, the study sought to assess linkage between these two institutions to provide farmers with information. A positivism paradigm with quantitative research approach were adopted in the study. Smallholder farmers (169), agricultural extension officers (5) and librarians (15) were the unit of analysis. A semi-structured questionnaire was used for data collection and SPSS software for analysis. Findings revealed that, agricultural extension officers mostly utilise interpersonal channels that include demonstrations, group meetings and face-to-face interaction to provide farmers with information. Community libraries were found to be non-utilised by extension services and also by farmers. Farmers were of the perception that libraries are meant for educated people. It was also discovered that community libraries have information on agriculture that only targets learners who are taking agriculture in school as a subject. There was no existing linkage between agricultural extension services and community libraries working together to provide farmers with pertinent agricultural information that can help them improve productivity
- Full Text:
- Date Issued: 2020
Acetophenone substituted phthalocyanines and their graphene quantum dots conjugates as photosensitizers for photodynamic antimicrobial chemotherapy against Staphylococcus aureus
- Openda, Yolande I, Sen, Pinar, Managa, Muthumuni, Nyokong, Tebello
- Authors: Openda, Yolande I , Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186507 , vital:44506 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.101607"
- Description: This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.
- Full Text:
- Date Issued: 2020
- Authors: Openda, Yolande I , Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186507 , vital:44506 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.101607"
- Description: This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.
- Full Text:
- Date Issued: 2020
Activity of diverse chalcones against several targets: statistical analysis of a high-throughput virtual screen of a custom chalcone library
- Authors: Sarron, Arthur F D
- Date: 2020
- Subjects: Acetophenone , Benzaldehyde , Ketones , Pyruvate kinase , Drug development , Aromatic compounds , Heat shock proteins
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/116028 , vital:34291
- Description: Chalcone family molecules are well known to have therapeutic proprieties (anti-inflammatory, anti-microbial or anti-cancer, etc). However the mechanism of action in some cases is not well known. A virtual library of this family of compounds was constructed using custom scripts, based on the aldol condensation, and this library was modified further to analogues by expansion of the α,β-unsaturated ketone linker. Acetophenone and benzaldehyde derivatives which are available and purchasable were used as a base to design the chalcone virtual library. 8063 chalcones were constructed and geometrically optimized with Gaussian 09. Their physicochemical characteristics linked to the Lipinski rules were analyzed with Knime and CDK. The entire library was after docked against several targets including HIV-1 integrase, MRSA pyruvate kinase, HSP90, COX-1, COX-2, ALR2, MAOA, MAOB, acetylcholinesterase, butyrylcholinesterase and PLA2. With the exception of MAOA, which does not have a crystal structure ligand, all dockings were validated by redocking the original ligand provided by the literature. These targets are known in the literature to be inhibited by chalcone-derivatives. However, specificity of the particular known chalcone inhibitors to the particular targets is not known. To this end the performance of the generated chalcone library against the list of targets was of interest. The binding energy of ligand-protein complexes was generally good across the library. Statistical analysis including principal component analysis and hierarchical clustering analysis were made in order to investigate for any physical/chemical characteristics which might explain what chalcone features affect the binding energy of the ligand-protein complexes. The spherical polar coordinates defining the orientation of the binding poses were also calculated and used in the statistical analysis. The statistical analysis has allowed us to hypothesize the importance of these radial distances and the polar angles of key atoms in the chalcones in binding to the pyruvate kinase crystal structure. This was validated by the docking of another small library of compound models in which the α,β-unsaturated ketone chain of the chalcone was replaced by incrementally longer conjugated chains. Further studies on the chalcones themselves reveal rotameric systems in both cis and trans-configurations (which may impact binding), and also studied was the effect of Topliss-based modification and its impact of binding to HSP90. Molecular dynamics confirmed good binding of identified chalcone hits.
- Full Text:
- Date Issued: 2020
- Authors: Sarron, Arthur F D
- Date: 2020
- Subjects: Acetophenone , Benzaldehyde , Ketones , Pyruvate kinase , Drug development , Aromatic compounds , Heat shock proteins
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/116028 , vital:34291
- Description: Chalcone family molecules are well known to have therapeutic proprieties (anti-inflammatory, anti-microbial or anti-cancer, etc). However the mechanism of action in some cases is not well known. A virtual library of this family of compounds was constructed using custom scripts, based on the aldol condensation, and this library was modified further to analogues by expansion of the α,β-unsaturated ketone linker. Acetophenone and benzaldehyde derivatives which are available and purchasable were used as a base to design the chalcone virtual library. 8063 chalcones were constructed and geometrically optimized with Gaussian 09. Their physicochemical characteristics linked to the Lipinski rules were analyzed with Knime and CDK. The entire library was after docked against several targets including HIV-1 integrase, MRSA pyruvate kinase, HSP90, COX-1, COX-2, ALR2, MAOA, MAOB, acetylcholinesterase, butyrylcholinesterase and PLA2. With the exception of MAOA, which does not have a crystal structure ligand, all dockings were validated by redocking the original ligand provided by the literature. These targets are known in the literature to be inhibited by chalcone-derivatives. However, specificity of the particular known chalcone inhibitors to the particular targets is not known. To this end the performance of the generated chalcone library against the list of targets was of interest. The binding energy of ligand-protein complexes was generally good across the library. Statistical analysis including principal component analysis and hierarchical clustering analysis were made in order to investigate for any physical/chemical characteristics which might explain what chalcone features affect the binding energy of the ligand-protein complexes. The spherical polar coordinates defining the orientation of the binding poses were also calculated and used in the statistical analysis. The statistical analysis has allowed us to hypothesize the importance of these radial distances and the polar angles of key atoms in the chalcones in binding to the pyruvate kinase crystal structure. This was validated by the docking of another small library of compound models in which the α,β-unsaturated ketone chain of the chalcone was replaced by incrementally longer conjugated chains. Further studies on the chalcones themselves reveal rotameric systems in both cis and trans-configurations (which may impact binding), and also studied was the effect of Topliss-based modification and its impact of binding to HSP90. Molecular dynamics confirmed good binding of identified chalcone hits.
- Full Text:
- Date Issued: 2020
Adaptive Neuro-Fuzzy Inference System modelling of surface topology in ultra-high precision diamond turning of rapidly solidified aluminium grade (RSA 443)
- Authors: Zvikomborero, Hweju
- Date: 2020
- Subjects: Mechatronics Surface roughness -- Measurement
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49441 , vital:41721
- Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
- Full Text:
- Date Issued: 2020
- Authors: Zvikomborero, Hweju
- Date: 2020
- Subjects: Mechatronics Surface roughness -- Measurement
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49441 , vital:41721
- Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
- Full Text:
- Date Issued: 2020
Addo Elephant National Park 1900 – 1955: An Environmental History of the struggle between elephants and emerging commercial farmers in the Sundays River Valley
- Jones,Nicholas Austen Inskip
- Authors: Jones,Nicholas Austen Inskip
- Date: 2020
- Subjects: Wildlife conservation -- South Africa -- Addo National Park
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46922 , vital:39733
- Description: The research covers the first half of the 20th Century in the Sundays River Valley, and the relations between the elephants and the local farmers. The research includes some discussion of the implementation of new ideas to agriculture, irrigation, and colonial settlement with the interplay between the colonial farmers and the Administration. There is reference to the early politics surrounding nature conservation and the difficulties faced by farmers from wildlife and the difficulty wildlife face trying to co-exist alongside early intensive commercial agriculture.Included is the decision making process of the Colonial administration with reference to wildlife and agriculture relating to charismatic animal species.
- Full Text:
- Date Issued: 2020
- Authors: Jones,Nicholas Austen Inskip
- Date: 2020
- Subjects: Wildlife conservation -- South Africa -- Addo National Park
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46922 , vital:39733
- Description: The research covers the first half of the 20th Century in the Sundays River Valley, and the relations between the elephants and the local farmers. The research includes some discussion of the implementation of new ideas to agriculture, irrigation, and colonial settlement with the interplay between the colonial farmers and the Administration. There is reference to the early politics surrounding nature conservation and the difficulties faced by farmers from wildlife and the difficulty wildlife face trying to co-exist alongside early intensive commercial agriculture.Included is the decision making process of the Colonial administration with reference to wildlife and agriculture relating to charismatic animal species.
- Full Text:
- Date Issued: 2020
Addressing flux suppression, radio frequency interference, and selection of optimal solution intervals during radio interferometric calibration
- Authors: Sob, Ulrich Armel Mbou
- Date: 2020
- Subjects: CubiCal (Software) , Radio -- Interference , Imaging systems in astronomy , Algorithms , Astronomical instruments -- Calibration , Astronomy -- Data processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147714 , vital:38663
- Description: The forthcoming Square Kilometre Array is expected to provide answers to some of the most intriguing questions about our Universe. However, as it is already noticeable from MeerKAT and other precursors, the amounts of data produced by these new instruments are significantly challenging to calibrate and image. Calibration of radio interferometric data is usually biased by incomplete sky models and radio frequency interference (RFI) resulting in calibration artefacts that limit the dynamic range and image fidelity of the resulting images. One of the most noticeable of these artefacts is the formation of spurious sources which causes suppression of real emissions. Fortunately, it has been shown that calibration algorithms employing heavy-tailed likelihood functions are less susceptible to this due to their robustness against outliers. Leveraging on recent developments in the field of complex optimisation, we implement a robust calibration algorithm using a Student’s t likelihood function and Wirtinger derivatives. The new algorithm, dubbed the robust solver, is incorporated as a subroutine into the newly released calibration software package CubiCal. We perform statistical analysis on the distribution of visibilities and provide an insight into the functioning of the robust solver and describe different scenarios where it will improve calibration. We use simulations to show that the robust solver effectively reduces the amount of flux suppressed from unmodelled sources both in direction independent and direction dependent calibration. Furthermore, the robust solver is shown to successfully mitigate the effects of low-level RFI when applied to a simulated and a real VLA dataset. Finally, we demonstrate that there are close links between the amount of flux suppressed from sources, the effects of the RFI and the employed solution interval during radio interferometric calibration. Hence, we investigate the effects of solution intervals and the different factors to consider in order to select adequate solution intervals. Furthermore, we propose a practical brute force method for selecting optimal solution intervals. The proposed method is successfully applied to a VLA dataset.
- Full Text:
- Date Issued: 2020
- Authors: Sob, Ulrich Armel Mbou
- Date: 2020
- Subjects: CubiCal (Software) , Radio -- Interference , Imaging systems in astronomy , Algorithms , Astronomical instruments -- Calibration , Astronomy -- Data processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147714 , vital:38663
- Description: The forthcoming Square Kilometre Array is expected to provide answers to some of the most intriguing questions about our Universe. However, as it is already noticeable from MeerKAT and other precursors, the amounts of data produced by these new instruments are significantly challenging to calibrate and image. Calibration of radio interferometric data is usually biased by incomplete sky models and radio frequency interference (RFI) resulting in calibration artefacts that limit the dynamic range and image fidelity of the resulting images. One of the most noticeable of these artefacts is the formation of spurious sources which causes suppression of real emissions. Fortunately, it has been shown that calibration algorithms employing heavy-tailed likelihood functions are less susceptible to this due to their robustness against outliers. Leveraging on recent developments in the field of complex optimisation, we implement a robust calibration algorithm using a Student’s t likelihood function and Wirtinger derivatives. The new algorithm, dubbed the robust solver, is incorporated as a subroutine into the newly released calibration software package CubiCal. We perform statistical analysis on the distribution of visibilities and provide an insight into the functioning of the robust solver and describe different scenarios where it will improve calibration. We use simulations to show that the robust solver effectively reduces the amount of flux suppressed from unmodelled sources both in direction independent and direction dependent calibration. Furthermore, the robust solver is shown to successfully mitigate the effects of low-level RFI when applied to a simulated and a real VLA dataset. Finally, we demonstrate that there are close links between the amount of flux suppressed from sources, the effects of the RFI and the employed solution interval during radio interferometric calibration. Hence, we investigate the effects of solution intervals and the different factors to consider in order to select adequate solution intervals. Furthermore, we propose a practical brute force method for selecting optimal solution intervals. The proposed method is successfully applied to a VLA dataset.
- Full Text:
- Date Issued: 2020
Adol-Safety: A Framework for Empowering Parents to be Aware of Social Network Threats Affecting Adolescents
- Mjoli, Phumelela, Shibeshi, Z
- Authors: Mjoli, Phumelela , Shibeshi, Z
- Date: 2020
- Subjects: Social networks Social media|
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/12016 , vital:39127
- Description: The use of social networks has grown so much that adolescents have become active members of various social networks such as Twitter, Facebook, and Instagram, etc. The gradual change in how people choose to communicate, socialize and share ideas today has influenced adolescents to an extent that they find themselves wanting to engage more on social networks than they really should due to peer pressure. Whenever a person joins social networks or browses the Internet, they by default are exposed and become vulnerable to many cyber threats. Cyber threats are driven by users that have negative intentions on the Internet or social networks. Adolescents are no exception to these cyber threats. The findings of this research reveal that threats such as cyberbullying, harassment, and online predators to name a few are often designed to abuse and affect adolescents). Therefore, this research aims to prevent such threats from prevailing by empowering parents to be aware of the threats that affect their adolescents in an online environment, which typically includes social networks. To achieve this, this research starts by investigating the cyber threats that affect adolescents and then explores ways that can be used to empower parents. A framework is developed to handle this. The framework includes strategies that parents can adopt and ways in which safety on social networks can be increased, as well as guidelines that can be followed in order to prevent cyber threats. The framework also aims to enhance a parent-child relationship that can help in preventing social network threats. Lastly, the framework is implemented as a knowledgesharing website that can be used by parents to receive and give an insight into social network threats that influence adolescents on social networks.
- Full Text:
- Date Issued: 2020
- Authors: Mjoli, Phumelela , Shibeshi, Z
- Date: 2020
- Subjects: Social networks Social media|
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/12016 , vital:39127
- Description: The use of social networks has grown so much that adolescents have become active members of various social networks such as Twitter, Facebook, and Instagram, etc. The gradual change in how people choose to communicate, socialize and share ideas today has influenced adolescents to an extent that they find themselves wanting to engage more on social networks than they really should due to peer pressure. Whenever a person joins social networks or browses the Internet, they by default are exposed and become vulnerable to many cyber threats. Cyber threats are driven by users that have negative intentions on the Internet or social networks. Adolescents are no exception to these cyber threats. The findings of this research reveal that threats such as cyberbullying, harassment, and online predators to name a few are often designed to abuse and affect adolescents). Therefore, this research aims to prevent such threats from prevailing by empowering parents to be aware of the threats that affect their adolescents in an online environment, which typically includes social networks. To achieve this, this research starts by investigating the cyber threats that affect adolescents and then explores ways that can be used to empower parents. A framework is developed to handle this. The framework includes strategies that parents can adopt and ways in which safety on social networks can be increased, as well as guidelines that can be followed in order to prevent cyber threats. The framework also aims to enhance a parent-child relationship that can help in preventing social network threats. Lastly, the framework is implemented as a knowledgesharing website that can be used by parents to receive and give an insight into social network threats that influence adolescents on social networks.
- Full Text:
- Date Issued: 2020
African Foreign Policies: Selecting signifiers to explain agency
- Authors: Bischoff, Paul, 1954-
- Date: 2020
- Subjects: Africa Foreign relations 1960- , Africa Politics and government 1960-
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/161716 , vital:40657 , ISBN 9780367348281 , https://www.routledge.com/African-Foreign-Policies-Selecting-Signifiers-to-Explain-Agency/Bischoff/p/book/9780367348281
- Description: This book explores, at a time when several powers have become serious players on the continent, aspects of African agency, past and present, by African writers on foreign policy, representative of geography, language and state size. In the past, African foreign policy has largely been considered within the context of reactions to the international or global 'external factor'. This ground-breaking book, however, looks at how foreign policy has been crafted and used in response not just to external, but also, mainly, domestic imperatives or (theoretical) signifiers. As such, it narrates individual and changing foreign policy orientations over time - and as far back as independence - with mainly African-based scholars who present their own constructs of what is a useful theoretical narrative regarding foreign policy on the continent - how theory is adapted to local circumstance or substituted for continentally based ontologies. The book therefore contends that the African experience carries valuable import for expanding general understandings of foreign policy in general. This book will be of key interest to scholars and students of Foreign Policy Analysis, Foreign Policy Studies, African International Relations/Politics/Studies, Diplomacy and more broadly to International Relations. , Introduction / Paul-Henri Bischoff -- What Next? Past and present African foreign policy concepts and practices / Paul-Henri Bischoff -- The African Union as a Foreign Policy Player: African Agency in International Cooperation / Tshepo Gwatiwa -- Unprincipled Pragmatism and Anti-Imperialist Impulses in an Interconnected World: The Zuma Presidency, 2009-2017 / Mzukisi Qobo -- Towards A Strategic Culture Approach to Understanding and Conceptualising Ethiopia's Foreign Policy Towards Israel and the Middle Eastern Arab Countries / Makonnen Tesfaye -- Nigeria's Foreign Policy and Intervention Behaviour in Africa: What Role for Agency? / Olumuyiwa Amao -- Zimbabwe and New Signifiers: Towards a cultural political economy of Foreign Policy Making / Mike Mavura -- Realist Conceptions of Kenya's Foreign Policy and Foreign Policy Behaviour: A Theoretical and Contextual Disposition / Korwa Gombe Adar and Mercy Kathambi Kaburu -- Addressing the Conceptual Void of African Small State Foreign Policy in Orthodox Theory: A Case Study of Botswana's Principled Pragmatism / Kabelo M. Mahupela -- Tunisia's Foreign Policy Towards France Before and After an Undemanding 'Revolution': A Theoretical Explanation of the An-Nahdha-led Interim Governments' Soft Policy / Ahmed Ali Salem -- Straddling Between Convergence and Divergence: A Constructivist's View of Malawi's Foreign Policy in Post-independence Africa / Eugenio Njoloma -- Strategies of a Small State Between Realism and Liberalism: Sixty Years of Guinea's Diplomacy and Foreign Policy (1958-2018) / Issaka K. Souaré -- Rethinking SADC's Collective Policymaking Processes on External Relations and Non-state Participation for Region-building / Cecilia Lwiindi Nedziwe -- Towards an Understanding of the Interplay Between Ghana's Foreign and Defence Policies / Kwesi Aning and Kwaku Danso -- Conclusion / Paul-Henri Bischoff
- Full Text:
- Date Issued: 2020
- Authors: Bischoff, Paul, 1954-
- Date: 2020
- Subjects: Africa Foreign relations 1960- , Africa Politics and government 1960-
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/161716 , vital:40657 , ISBN 9780367348281 , https://www.routledge.com/African-Foreign-Policies-Selecting-Signifiers-to-Explain-Agency/Bischoff/p/book/9780367348281
- Description: This book explores, at a time when several powers have become serious players on the continent, aspects of African agency, past and present, by African writers on foreign policy, representative of geography, language and state size. In the past, African foreign policy has largely been considered within the context of reactions to the international or global 'external factor'. This ground-breaking book, however, looks at how foreign policy has been crafted and used in response not just to external, but also, mainly, domestic imperatives or (theoretical) signifiers. As such, it narrates individual and changing foreign policy orientations over time - and as far back as independence - with mainly African-based scholars who present their own constructs of what is a useful theoretical narrative regarding foreign policy on the continent - how theory is adapted to local circumstance or substituted for continentally based ontologies. The book therefore contends that the African experience carries valuable import for expanding general understandings of foreign policy in general. This book will be of key interest to scholars and students of Foreign Policy Analysis, Foreign Policy Studies, African International Relations/Politics/Studies, Diplomacy and more broadly to International Relations. , Introduction / Paul-Henri Bischoff -- What Next? Past and present African foreign policy concepts and practices / Paul-Henri Bischoff -- The African Union as a Foreign Policy Player: African Agency in International Cooperation / Tshepo Gwatiwa -- Unprincipled Pragmatism and Anti-Imperialist Impulses in an Interconnected World: The Zuma Presidency, 2009-2017 / Mzukisi Qobo -- Towards A Strategic Culture Approach to Understanding and Conceptualising Ethiopia's Foreign Policy Towards Israel and the Middle Eastern Arab Countries / Makonnen Tesfaye -- Nigeria's Foreign Policy and Intervention Behaviour in Africa: What Role for Agency? / Olumuyiwa Amao -- Zimbabwe and New Signifiers: Towards a cultural political economy of Foreign Policy Making / Mike Mavura -- Realist Conceptions of Kenya's Foreign Policy and Foreign Policy Behaviour: A Theoretical and Contextual Disposition / Korwa Gombe Adar and Mercy Kathambi Kaburu -- Addressing the Conceptual Void of African Small State Foreign Policy in Orthodox Theory: A Case Study of Botswana's Principled Pragmatism / Kabelo M. Mahupela -- Tunisia's Foreign Policy Towards France Before and After an Undemanding 'Revolution': A Theoretical Explanation of the An-Nahdha-led Interim Governments' Soft Policy / Ahmed Ali Salem -- Straddling Between Convergence and Divergence: A Constructivist's View of Malawi's Foreign Policy in Post-independence Africa / Eugenio Njoloma -- Strategies of a Small State Between Realism and Liberalism: Sixty Years of Guinea's Diplomacy and Foreign Policy (1958-2018) / Issaka K. Souaré -- Rethinking SADC's Collective Policymaking Processes on External Relations and Non-state Participation for Region-building / Cecilia Lwiindi Nedziwe -- Towards an Understanding of the Interplay Between Ghana's Foreign and Defence Policies / Kwesi Aning and Kwaku Danso -- Conclusion / Paul-Henri Bischoff
- Full Text:
- Date Issued: 2020
Afromelampsalta, a new genus, a new species, and five new combinations of African cicadettine cicadas (Hemiptera: Cicadidae: Cicadettinae):
- Sanborn, Allen F, Villet, Martin H
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140680 , vital:37909
- Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
- Full Text:
- Date Issued: 2020
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140680 , vital:37909
- Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
- Full Text:
- Date Issued: 2020
Age is nothing but a number: Ben 10s, sugar mummies, and the South African gender order in the Daily Sun’s Facebook page
- Authors: Mlangeni, Ntombikayise Lina
- Date: 2020
- Subjects: May-December romances -- South Africa , Women in mass media , Men in mass media , Sex role in mass media , Masculinity in mass media , Feminism and mass media , Critical discourse analysis , Unemployment -- Social aspects -- South Africa , Daily Sun (South Africa) , Ben 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167077 , vital:41435
- Description: This thesis examines how meanings of masculinity and femininity are negotiated by South Africans on a social media platform linked to a popular local tabloid newspaper. In particular it explores conversations surrounding the Ben 10 phenomenon on the Daily Sun’s Facebook page. A Ben 10 is commonly understood as a young man who enters into a sexual relationship with an older woman, mostly in township settings, and readers engage vociferously over the meanings of such relationships. Using a constructivist understanding of gender, a thematic analysis is used to examine the Facebook comments on the Daily Sun’s most popular Ben 10 stories. South Africa’s constitution promotes the right to gender equality and freedom, which contributes to the normalisation of sex in public conversations and political debate. However, with high levels of unemployment and poverty in South Africa, the narrative of masculine success through work remains relatively unattainable. This tension between the narrative of male-bread winner through work and the reality of South Africa’s poverty and unemployment has been referred to as the crisis of masculinity. This thesis will argue that tabloids can play a strong political role by providing an alternative public sphere and that they can also assist their readers in coping with life in a democratic society by creating an imagined community of people sharing common experiences.
- Full Text:
- Date Issued: 2020
- Authors: Mlangeni, Ntombikayise Lina
- Date: 2020
- Subjects: May-December romances -- South Africa , Women in mass media , Men in mass media , Sex role in mass media , Masculinity in mass media , Feminism and mass media , Critical discourse analysis , Unemployment -- Social aspects -- South Africa , Daily Sun (South Africa) , Ben 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167077 , vital:41435
- Description: This thesis examines how meanings of masculinity and femininity are negotiated by South Africans on a social media platform linked to a popular local tabloid newspaper. In particular it explores conversations surrounding the Ben 10 phenomenon on the Daily Sun’s Facebook page. A Ben 10 is commonly understood as a young man who enters into a sexual relationship with an older woman, mostly in township settings, and readers engage vociferously over the meanings of such relationships. Using a constructivist understanding of gender, a thematic analysis is used to examine the Facebook comments on the Daily Sun’s most popular Ben 10 stories. South Africa’s constitution promotes the right to gender equality and freedom, which contributes to the normalisation of sex in public conversations and political debate. However, with high levels of unemployment and poverty in South Africa, the narrative of masculine success through work remains relatively unattainable. This tension between the narrative of male-bread winner through work and the reality of South Africa’s poverty and unemployment has been referred to as the crisis of masculinity. This thesis will argue that tabloids can play a strong political role by providing an alternative public sphere and that they can also assist their readers in coping with life in a democratic society by creating an imagined community of people sharing common experiences.
- Full Text:
- Date Issued: 2020
Age of squid Loligo reynaudii d’Orbigny, 1845, and its possible use to test effectiveness of the closed season in protecting this resource
- Mwanangombe, Collette Habani
- Authors: Mwanangombe, Collette Habani
- Date: 2020
- Subjects: Loliginidae -- Spawning -- South Africa , Loliginidae -- Age determination , Loligo fisheries -- South Africa , Fishery management -- South Africa , Otoliths , Loliginidae – Eggs -- Incubation , Loliginidae – Growth , Fish stock assessment -- South Africa , Recruitment (Population biology) -- South Africa , Loligo reynaudii d’Orbigny
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/144333 , vital:38336
- Description: This study presents age distributions representing populations of adult Loligo reynaudii, together with the results of spawning and commercial catches to assist in understanding the beneficial role of the closed season. The results were based on 791 samples collected during three closed seasons (November: 2003, 2004 and 2005) and out of closed season during April/May 2005. Age and predicted growth were examined by counting daily rings on statolith microstructures. The age in days after hatching ranged from 168 to 484 days (71-425 mm) in males and from 125 to 478 days (83-263 mm) in females. Average age at spawning was found to be 323 days in males and 316 days in females. Population estimates of growth rates were best described by a linear growth model which revealed that males grew faster than females in length as they grew older with growth rate ranging between 0.63 to 0.83 mm per day for males and between 0.22 to 0.32 mm per day for females. Back-calculated hatch dates and later egg-laying events for parental populations were determined. Results from back calculated egg laying dates (presented as percentage of frequency of all laying dates) indicated a highest total of 36%, 39% and 15% of eggs from all samples were laid during the closed season and nine days after the closed season during year 2003, 2004 and 2005 respectively. Monthly commercial total catches (2002-2005) showed an increase from November soon after the fishery resumed, up until the month of January. Daily catches were highest in November (up to 290 tonnes) relative to the daily catches observed in December and January in all the years. Results led to the conclusion that the closed season (25 October to 22 November) is beneficial for both the chokka resource and the fishery. This is because: a) there is time for enough spawning biomass to accumulate, which subsequently results in high catches (good fishery), in the current year, best immediately after season opens in November; b) there is a link in the results between egg laying dates in the period of closed season and immediately afterwards, and the magnitude of catches in last nine days of November.
- Full Text:
- Date Issued: 2020
- Authors: Mwanangombe, Collette Habani
- Date: 2020
- Subjects: Loliginidae -- Spawning -- South Africa , Loliginidae -- Age determination , Loligo fisheries -- South Africa , Fishery management -- South Africa , Otoliths , Loliginidae – Eggs -- Incubation , Loliginidae – Growth , Fish stock assessment -- South Africa , Recruitment (Population biology) -- South Africa , Loligo reynaudii d’Orbigny
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/144333 , vital:38336
- Description: This study presents age distributions representing populations of adult Loligo reynaudii, together with the results of spawning and commercial catches to assist in understanding the beneficial role of the closed season. The results were based on 791 samples collected during three closed seasons (November: 2003, 2004 and 2005) and out of closed season during April/May 2005. Age and predicted growth were examined by counting daily rings on statolith microstructures. The age in days after hatching ranged from 168 to 484 days (71-425 mm) in males and from 125 to 478 days (83-263 mm) in females. Average age at spawning was found to be 323 days in males and 316 days in females. Population estimates of growth rates were best described by a linear growth model which revealed that males grew faster than females in length as they grew older with growth rate ranging between 0.63 to 0.83 mm per day for males and between 0.22 to 0.32 mm per day for females. Back-calculated hatch dates and later egg-laying events for parental populations were determined. Results from back calculated egg laying dates (presented as percentage of frequency of all laying dates) indicated a highest total of 36%, 39% and 15% of eggs from all samples were laid during the closed season and nine days after the closed season during year 2003, 2004 and 2005 respectively. Monthly commercial total catches (2002-2005) showed an increase from November soon after the fishery resumed, up until the month of January. Daily catches were highest in November (up to 290 tonnes) relative to the daily catches observed in December and January in all the years. Results led to the conclusion that the closed season (25 October to 22 November) is beneficial for both the chokka resource and the fishery. This is because: a) there is time for enough spawning biomass to accumulate, which subsequently results in high catches (good fishery), in the current year, best immediately after season opens in November; b) there is a link in the results between egg laying dates in the period of closed season and immediately afterwards, and the magnitude of catches in last nine days of November.
- Full Text:
- Date Issued: 2020
Agents sans frontiers: cross-border aquatic weed biological control in the rivers of southern Mozambique
- Langa, Sílvia da Fátima, Hill, Martin P, Compton, Stephen G
- Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
- Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
- Full Text:
- Date Issued: 2020
- Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
- Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
- Full Text:
- Date Issued: 2020
Aileen wuornos : a psychobiographical study
- Authors: Fakude, Shuanize Xiluva
- Date: 2020
- Subjects: Women serial murderers
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/50789 , vital:42700
- Description: A psychobiographical study is an exploration of a unique individual’s entire lived life through a psychological lens. The aim of the study was to explore and describe the personality development of Aileen Wuornos within her socio-historical context by applying Erikson’s Theory of Psychosocial Development. Aileen Carol Wuornos was an American serial killer who murdered seven men in Florida between 1989 and 1990 by shooting them at point blank range. Wuornos’s life was marked by a difficult formative environment, maternal abandonment, and adoption by her grandparents. Wuornos continued to experience physical, emotional and sexual abuse at the hands of family members, friends and the community. Wuornos lived her life focusing on survival, and started to engage with petty crime and prostitution to do so. Her patterns escalated to include more serious criminal behaviour, culminating in serial murder. Wuornos was selected for this study using nonpropability purposive sampling. She was selected based on the researcher’s curiosity of her life events and experiences that led her to commit serial murders. Data was collected through a variety of primary and secondary sources on Wuornos and it was analysed using Miles and Huberman’s three steps process of data analysis, which includes data reduction, data display, and conclusion drawing and verification. The findings of this study indicate that Wuornos experiences severe difficulties in renegotiating the seven stages proposed by Erikson’s Theory of Psychosocial Development, and all the ego strengths that she developed were seriously delayed.
- Full Text: false
- Date Issued: 2020
- Authors: Fakude, Shuanize Xiluva
- Date: 2020
- Subjects: Women serial murderers
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/50789 , vital:42700
- Description: A psychobiographical study is an exploration of a unique individual’s entire lived life through a psychological lens. The aim of the study was to explore and describe the personality development of Aileen Wuornos within her socio-historical context by applying Erikson’s Theory of Psychosocial Development. Aileen Carol Wuornos was an American serial killer who murdered seven men in Florida between 1989 and 1990 by shooting them at point blank range. Wuornos’s life was marked by a difficult formative environment, maternal abandonment, and adoption by her grandparents. Wuornos continued to experience physical, emotional and sexual abuse at the hands of family members, friends and the community. Wuornos lived her life focusing on survival, and started to engage with petty crime and prostitution to do so. Her patterns escalated to include more serious criminal behaviour, culminating in serial murder. Wuornos was selected for this study using nonpropability purposive sampling. She was selected based on the researcher’s curiosity of her life events and experiences that led her to commit serial murders. Data was collected through a variety of primary and secondary sources on Wuornos and it was analysed using Miles and Huberman’s three steps process of data analysis, which includes data reduction, data display, and conclusion drawing and verification. The findings of this study indicate that Wuornos experiences severe difficulties in renegotiating the seven stages proposed by Erikson’s Theory of Psychosocial Development, and all the ego strengths that she developed were seriously delayed.
- Full Text: false
- Date Issued: 2020
Alignment in the orientation of LOFAR radio sources:
- Osinga, E, Miley, G K, van Weeren, R J, Shimwell, T W, Duncan, K J, Hardcastle, M J, Mechev, A P, Röttgering, H J A, Tasse, C, Williams, W L
- Authors: Osinga, E , Miley, G K , van Weeren, R J , Shimwell, T W , Duncan, K J , Hardcastle, M J , Mechev, A P , Röttgering, H J A , Tasse, C , Williams, W L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163452 , vital:41039 , https://doi.org/10.1051/0004-6361/202037680
- Description: Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei over large distances, but these results have proven controversial and so far, there is no clear explanation for this observed alignment. To investigate this case further, we tested the hypothesis that the position angles of radio galaxies are randomly oriented in the sky by using data from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS). A sample of 7555 double-lobed radio galaxies was extracted from the list of 318 520 radio sources in the first data release of LoTSS at 150 MHz. We performed statistical tests for uniformity of the two-dimensional (2D) orientations for the complete 7555 source sample. We also tested the orientation uniformity in three dimensions (3D) for the 4212 source sub-sample with photometric or spectroscopic redshifts.
- Full Text:
- Date Issued: 2020
- Authors: Osinga, E , Miley, G K , van Weeren, R J , Shimwell, T W , Duncan, K J , Hardcastle, M J , Mechev, A P , Röttgering, H J A , Tasse, C , Williams, W L
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163452 , vital:41039 , https://doi.org/10.1051/0004-6361/202037680
- Description: Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei over large distances, but these results have proven controversial and so far, there is no clear explanation for this observed alignment. To investigate this case further, we tested the hypothesis that the position angles of radio galaxies are randomly oriented in the sky by using data from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS). A sample of 7555 double-lobed radio galaxies was extracted from the list of 318 520 radio sources in the first data release of LoTSS at 150 MHz. We performed statistical tests for uniformity of the two-dimensional (2D) orientations for the complete 7555 source sample. We also tested the orientation uniformity in three dimensions (3D) for the 4212 source sub-sample with photometric or spectroscopic redshifts.
- Full Text:
- Date Issued: 2020
Alternative pine species/hybrids for the Cape timber growing regions of South Africa
- Authors: Van der Hoef, André
- Date: 2020
- Subjects: Species -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/47613 , vital:40258
- Description: Pinus radiata has been the preferred commercial sawtimber species for the Cape forestry region for many years. Since the introduction of Fusarium circinatum, and the susceptibility of P. radiata to this disease, the sustainable production of this pine species for the Cape has been negatively impacted due to poor survival in the nursery and in field plantings. For this reason, a number of additional pine species and hybrids have been established in the Cape region of South Africa since 2006 to identify taxa that would perform as well as or better than P. radiata. Three research trials were implemented on contrasting sites that contained eight common species/hybrids treatments that included P. elliottii, P. elliottii x P. caribaea, P. radiata, P. patula x P. greggii var. australis, P. patula x P. oocarpa, P. patula x P. tecunumanii (HE), P. patula x P. tecunumanii (LE) and P. tecunumanii (HE) x P. oocarpa were established at Witelsbos, Kruisfontein and Garcia across diverse soil types, drainage and climate conditions in the Cape. Survival, growth data and tree morphology (forking, foxtails, broken tops and stem form) were assessed at five years of age and individual tree volume was calculated. Five year results indicate that on the waterlogged site at Witelsbos P. elliottii and its hybrid with P. caribaea was best in terms of productivity, at the dry site of Garcia, P. taeda and P. elliottii demonstrated promise, and at Kruisfontein, the most fertile site, P. elliottii x P. caribaea, P. patula x P. tecunumanii (LE) and P. maximinoi were found to be promising alternatives to P. radiata. Wood properties were assessed at Kruisfontein at six-years of age. Basic density and Modulus of Elasticity (MOE) were found to be significantly different for the various species/hybrids. Pinus patula x P. tecunumanii (LE), P. patula x P. greggii (S), P. maximinoi and P. patula x P. tecunumanii (HE) were all significantly better than P. radiata, which would suggest that these taxa would have similar or superior wood strength over P. radiata, the preferred sawtimber species for the Cape region. Only P. tecunumanii (HE) x P. oocarpa had a higher basic density than P. radiata, but not significantly different. Species that had similar basic density were P. patula x P. greggii (S), P. taeda and P. tecunumanii (LE) x P. caribaea. Although P. elliottii x P. caribaea had the highest volume at Witelsbos and Kruisfontein, the timber qualities were the worst, suggesting that some breeding is needed to improve this hybrid to be an acceptable sawtimber species. From this study, several potential alternative species/hybrids have been identified that are tolerant to the F. circinatum pathogen and have acceptable growth and wood properties, compared to P. radiata.
- Full Text:
- Date Issued: 2020
- Authors: Van der Hoef, André
- Date: 2020
- Subjects: Species -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/47613 , vital:40258
- Description: Pinus radiata has been the preferred commercial sawtimber species for the Cape forestry region for many years. Since the introduction of Fusarium circinatum, and the susceptibility of P. radiata to this disease, the sustainable production of this pine species for the Cape has been negatively impacted due to poor survival in the nursery and in field plantings. For this reason, a number of additional pine species and hybrids have been established in the Cape region of South Africa since 2006 to identify taxa that would perform as well as or better than P. radiata. Three research trials were implemented on contrasting sites that contained eight common species/hybrids treatments that included P. elliottii, P. elliottii x P. caribaea, P. radiata, P. patula x P. greggii var. australis, P. patula x P. oocarpa, P. patula x P. tecunumanii (HE), P. patula x P. tecunumanii (LE) and P. tecunumanii (HE) x P. oocarpa were established at Witelsbos, Kruisfontein and Garcia across diverse soil types, drainage and climate conditions in the Cape. Survival, growth data and tree morphology (forking, foxtails, broken tops and stem form) were assessed at five years of age and individual tree volume was calculated. Five year results indicate that on the waterlogged site at Witelsbos P. elliottii and its hybrid with P. caribaea was best in terms of productivity, at the dry site of Garcia, P. taeda and P. elliottii demonstrated promise, and at Kruisfontein, the most fertile site, P. elliottii x P. caribaea, P. patula x P. tecunumanii (LE) and P. maximinoi were found to be promising alternatives to P. radiata. Wood properties were assessed at Kruisfontein at six-years of age. Basic density and Modulus of Elasticity (MOE) were found to be significantly different for the various species/hybrids. Pinus patula x P. tecunumanii (LE), P. patula x P. greggii (S), P. maximinoi and P. patula x P. tecunumanii (HE) were all significantly better than P. radiata, which would suggest that these taxa would have similar or superior wood strength over P. radiata, the preferred sawtimber species for the Cape region. Only P. tecunumanii (HE) x P. oocarpa had a higher basic density than P. radiata, but not significantly different. Species that had similar basic density were P. patula x P. greggii (S), P. taeda and P. tecunumanii (LE) x P. caribaea. Although P. elliottii x P. caribaea had the highest volume at Witelsbos and Kruisfontein, the timber qualities were the worst, suggesting that some breeding is needed to improve this hybrid to be an acceptable sawtimber species. From this study, several potential alternative species/hybrids have been identified that are tolerant to the F. circinatum pathogen and have acceptable growth and wood properties, compared to P. radiata.
- Full Text:
- Date Issued: 2020
AMBER force field parameters for the Zn (II) ions of the tunneling-fold enzymes GTP cyclohydrolase I and 6-pyruvoyl tetrahydropterin synthase
- Khairallah, Afrah, Tastan Bishop, Ozlem, Moses, Vuyani
- Authors: Khairallah, Afrah , Tastan Bishop, Ozlem , Moses, Vuyani
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429360 , vital:72604 , xlink:href="https://doi.org/10.1080/07391102.2020.1796800"
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase. Both GCH1 and PTPS enzymes contain Zn2+ ions in their active sites, and to accurately study their dynamic behaviors using all-atom molecular dynamics (MD) simulations, appropriate parameters that can describe their metal sites should be developed and validated. In this study, force field parameters of the GCH1 and PTPS metal centers were generated using quantum mechanics (QM) calculations and then validated through MD simulations to ensure their accuracy in describing and maintaining the Zn2+ ion coordination environment. The derived force field parameters will provide accurate and reliable MD simulations involving these two enzymes for future in-silico identification of drug candidates against the GCH1 and PTPS enzymes.
- Full Text:
- Date Issued: 2020
- Authors: Khairallah, Afrah , Tastan Bishop, Ozlem , Moses, Vuyani
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/429360 , vital:72604 , xlink:href="https://doi.org/10.1080/07391102.2020.1796800"
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase. Both GCH1 and PTPS enzymes contain Zn2+ ions in their active sites, and to accurately study their dynamic behaviors using all-atom molecular dynamics (MD) simulations, appropriate parameters that can describe their metal sites should be developed and validated. In this study, force field parameters of the GCH1 and PTPS metal centers were generated using quantum mechanics (QM) calculations and then validated through MD simulations to ensure their accuracy in describing and maintaining the Zn2+ ion coordination environment. The derived force field parameters will provide accurate and reliable MD simulations involving these two enzymes for future in-silico identification of drug candidates against the GCH1 and PTPS enzymes.
- Full Text:
- Date Issued: 2020
AMBER force field parameters for the Zn (II) ions of the tunneling-fold enzymes GTP cyclohydrolase I and 6-pyruvoyl tetrahydropterin synthase:
- Khairallah, Afrah, Tastan Bishop, Özlem, Moses, Vuyani
- Authors: Khairallah, Afrah , Tastan Bishop, Özlem , Moses, Vuyani
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163068 , vital:41009 , DOI: 10.1080/07391102.2020.1796800
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase.
- Full Text:
- Date Issued: 2020
- Authors: Khairallah, Afrah , Tastan Bishop, Özlem , Moses, Vuyani
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163068 , vital:41009 , DOI: 10.1080/07391102.2020.1796800
- Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase.
- Full Text:
- Date Issued: 2020