A best practice guideline for screening and managing chorioamnionitis
- Authors: Du Plessis, Allison Herlene
- Date: 2020
- Subjects: Bacterial diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46374 , vital:39575
- Description: Due to the complex nature of chorioamnionitis, women are often misdiagnosed, undiagnosed or only diagnosed after birth when it is too late to prevent maternal and neonatal complications. A lack of a comprehensive best practice guidelinefor screening and managing women withchorioamnionitis resultsin delayed treatment and management that could minimise maternal and neonatal complications. Saving Babiesreported that unexplained intra-uterine deathsremained the main primary (obstetric) cause of death for babies with a weight above 1000g (24.4%of all deaths). Of these unexplained uterine deaths, 33% are of normal birth weight (>2500g), and,therefore,most likely term gestation. Saving Babies further reported that 22.9% of all live births in South Africa was premature and 22.8% of birthswere unexplained intra-uterine deaths. Prematurity is one major complication of chorioamnionitis. When susceptibility for chorioamnionitis is considered during early pregnancy, it is possible to intervene and prevent or even reduce the incidences and complications of chorioamnionitis.A qualitative research study was conducted in three phases. In Phase One(Part One), a theoretically constructed patient scenario of chorioamnionitis was presented to ten midwives,and semi-structured individual interviews were done to elicit information regarding how they screen for and manage chorioamnionitis. In Phase One(Part Two), experienced medical practitioners in the field of obstetrics and gynaecology were individually interviewed, also using semi-structured individual interviewsto gain their views regarding chorioamnionitis as a contributing factor to maternal morbidity and mortality. Qualitative findings in Phase Oneindicated that there is a general lack of knowledge regarding chorioamnionitis among midwives, resulting ininadequate screening, misdiagnosis and mismanagement of the condition. Experienced medical practitioners confirmed that chorioamnionitis is underdiagnosed, misdiagnosed or undiagnosed and underreported,and they hold views that it is difficult to treat and control pregnancy-related infections according to current practice.An integrative literature review was conductedin Phase Twoand literature regarding diagnostic biomarkers, screening options to diagnose chorioamnionitis and management of chorioamnionitis were extracted. After evidence synthesisofPhase Oneand Phase Twodata, a best practice guidelinefor screening and managing viiwomen withchorioamnionitiswas developed usingthe National Institute for Health and Clinical Excellence guideline development approach in Phase Three. The purpose of the best practice guideline for screening and managing women with chorioamnionitis was to provide a guideline onhow to manage women who are at risk and those who present with signs and symptoms of chorioamnionitis at any stage during their pregnancy. Five recommendations were made that involve screening for chorioamnionitisand causative factors, biomarkers to diagnose chorioamnionitis, management of chorioamnionitis that includes pharmacological and non-pharmacological management, and health education to women.Ethics for this research study were guided by the ethical principles and guidelines of the Belmont Report. The trustworthiness of this research study was adopted from Ravitch and Carl,and was based on criticality, reflexivity, collaboration, and rigour. An independent coder and reviewer wereto verify the data that were included in the best practice guideline. Expert reviewersappraised the best practice guidelineusing Appraisal of Guidelines for Research and Evaluation II tools.
- Full Text:
- Date Issued: 2020
- Authors: Du Plessis, Allison Herlene
- Date: 2020
- Subjects: Bacterial diseases
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/46374 , vital:39575
- Description: Due to the complex nature of chorioamnionitis, women are often misdiagnosed, undiagnosed or only diagnosed after birth when it is too late to prevent maternal and neonatal complications. A lack of a comprehensive best practice guidelinefor screening and managing women withchorioamnionitis resultsin delayed treatment and management that could minimise maternal and neonatal complications. Saving Babiesreported that unexplained intra-uterine deathsremained the main primary (obstetric) cause of death for babies with a weight above 1000g (24.4%of all deaths). Of these unexplained uterine deaths, 33% are of normal birth weight (>2500g), and,therefore,most likely term gestation. Saving Babies further reported that 22.9% of all live births in South Africa was premature and 22.8% of birthswere unexplained intra-uterine deaths. Prematurity is one major complication of chorioamnionitis. When susceptibility for chorioamnionitis is considered during early pregnancy, it is possible to intervene and prevent or even reduce the incidences and complications of chorioamnionitis.A qualitative research study was conducted in three phases. In Phase One(Part One), a theoretically constructed patient scenario of chorioamnionitis was presented to ten midwives,and semi-structured individual interviews were done to elicit information regarding how they screen for and manage chorioamnionitis. In Phase One(Part Two), experienced medical practitioners in the field of obstetrics and gynaecology were individually interviewed, also using semi-structured individual interviewsto gain their views regarding chorioamnionitis as a contributing factor to maternal morbidity and mortality. Qualitative findings in Phase Oneindicated that there is a general lack of knowledge regarding chorioamnionitis among midwives, resulting ininadequate screening, misdiagnosis and mismanagement of the condition. Experienced medical practitioners confirmed that chorioamnionitis is underdiagnosed, misdiagnosed or undiagnosed and underreported,and they hold views that it is difficult to treat and control pregnancy-related infections according to current practice.An integrative literature review was conductedin Phase Twoand literature regarding diagnostic biomarkers, screening options to diagnose chorioamnionitis and management of chorioamnionitis were extracted. After evidence synthesisofPhase Oneand Phase Twodata, a best practice guidelinefor screening and managing viiwomen withchorioamnionitiswas developed usingthe National Institute for Health and Clinical Excellence guideline development approach in Phase Three. The purpose of the best practice guideline for screening and managing women with chorioamnionitis was to provide a guideline onhow to manage women who are at risk and those who present with signs and symptoms of chorioamnionitis at any stage during their pregnancy. Five recommendations were made that involve screening for chorioamnionitisand causative factors, biomarkers to diagnose chorioamnionitis, management of chorioamnionitis that includes pharmacological and non-pharmacological management, and health education to women.Ethics for this research study were guided by the ethical principles and guidelines of the Belmont Report. The trustworthiness of this research study was adopted from Ravitch and Carl,and was based on criticality, reflexivity, collaboration, and rigour. An independent coder and reviewer wereto verify the data that were included in the best practice guideline. Expert reviewersappraised the best practice guidelineusing Appraisal of Guidelines for Research and Evaluation II tools.
- Full Text:
- Date Issued: 2020
A best-practice guideline for facilitating adherence to anti-retroviral therapy for persons attending public hospitals in Ghana
- Authors: Agyeman-Yeboah, Joana
- Date: 2017
- Subjects: HIV infections -- Treatment -- Ghana , Health services administration -- Ghana Public health -- Ghana Hospital care -- Ghana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/13603 , vital:27256
- Description: The retention of persons on an HIV programme has been a global challenge. The success of any strategy to optimize adherence to anti-retroviral therapy (ART) depends on the intensive and effective adherence counselling and strategies. It is important to research whether persons receiving anti-retroviral therapy in public hospitals in Ghana are receiving the needed service that would optimize their adherence to the anti-retroviral therapy. Therefore, this study explored and described the experiences of healthcare professionals providing care, support and guidance to persons on ART at public hospitals in Ghana, as well as the best-practice guideline that could contribute to facilitating the ART adherence of patients. This study also explored and described the experiences of persons living with Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) on ART, regarding their adherence to the therapy. The study was organized into three phases. In Phase One: a qualitative, exploratory, descriptive and contextual design was employed. The research population included healthcare professionals, providing services at the HIV clinic at the public hospitals in Ghana, namely the Korle-Bu Teaching Hospital; the 37 Military Hospital and the Ridge Hospital. The healthcare professionals comprised of doctors, nurses, pharmacists and trained counsellors employed in any of the three public hospitals. Persons receiving ART at any of the three public hospitals were also part of the research population. Semi-structured interviews were conducted with healthcare professionals and persons receiving ART. Data were collected from healthcare professionals in relation to their experiences regarding the provision of ART services, their understanding of evidence-based practice and best-practice guidelines, as well as data on the experiences of persons receiving ART in relation to their adherence to the therapy. The data were analysed using Creswell’s six steps of data analysis; and the coding of the data was done according to Tesch’s eight steps of coding. Trustworthiness was ensured by using Lincoln and Guba’s framework which comprised credibility, transferability, dependability, confirmability and authenticity. Ethical principles such as beneficence and non-maleficence, respect for human dignity, justice, veracity, privacy and confidentiality were considered in the study. In phase two, the literature was searched by using an integrative literature review approach and critically appraising the methodological quality of the guidelines in order to identify the best available evidence related to adherence to ART. In Phase Three, a best-practice guideline for facilitating adherence to ART was developed for public hospitals in Ghana based on the findings of the empirical research of Phase One and the integrative literature review in Phase Two. The guideline was submitted to an expert panel for review; and it was modified, according to the recommendations of the panel.
- Full Text:
- Date Issued: 2017
- Authors: Agyeman-Yeboah, Joana
- Date: 2017
- Subjects: HIV infections -- Treatment -- Ghana , Health services administration -- Ghana Public health -- Ghana Hospital care -- Ghana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/13603 , vital:27256
- Description: The retention of persons on an HIV programme has been a global challenge. The success of any strategy to optimize adherence to anti-retroviral therapy (ART) depends on the intensive and effective adherence counselling and strategies. It is important to research whether persons receiving anti-retroviral therapy in public hospitals in Ghana are receiving the needed service that would optimize their adherence to the anti-retroviral therapy. Therefore, this study explored and described the experiences of healthcare professionals providing care, support and guidance to persons on ART at public hospitals in Ghana, as well as the best-practice guideline that could contribute to facilitating the ART adherence of patients. This study also explored and described the experiences of persons living with Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome (HIV/AIDS) on ART, regarding their adherence to the therapy. The study was organized into three phases. In Phase One: a qualitative, exploratory, descriptive and contextual design was employed. The research population included healthcare professionals, providing services at the HIV clinic at the public hospitals in Ghana, namely the Korle-Bu Teaching Hospital; the 37 Military Hospital and the Ridge Hospital. The healthcare professionals comprised of doctors, nurses, pharmacists and trained counsellors employed in any of the three public hospitals. Persons receiving ART at any of the three public hospitals were also part of the research population. Semi-structured interviews were conducted with healthcare professionals and persons receiving ART. Data were collected from healthcare professionals in relation to their experiences regarding the provision of ART services, their understanding of evidence-based practice and best-practice guidelines, as well as data on the experiences of persons receiving ART in relation to their adherence to the therapy. The data were analysed using Creswell’s six steps of data analysis; and the coding of the data was done according to Tesch’s eight steps of coding. Trustworthiness was ensured by using Lincoln and Guba’s framework which comprised credibility, transferability, dependability, confirmability and authenticity. Ethical principles such as beneficence and non-maleficence, respect for human dignity, justice, veracity, privacy and confidentiality were considered in the study. In phase two, the literature was searched by using an integrative literature review approach and critically appraising the methodological quality of the guidelines in order to identify the best available evidence related to adherence to ART. In Phase Three, a best-practice guideline for facilitating adherence to ART was developed for public hospitals in Ghana based on the findings of the empirical research of Phase One and the integrative literature review in Phase Two. The guideline was submitted to an expert panel for review; and it was modified, according to the recommendations of the panel.
- Full Text:
- Date Issued: 2017
A bioinorganic study of some cobalt(II) Schiff base complexes of variously substituted hydroxybenzaldimines
- Authors: Shaibu, Rafiu Olarewaju
- Date: 2008
- Subjects: Cobalt Schiff bases Artemia Spectrum analysis Ligands -- Analysis Bioinorganic chemistry Antineoplastic agents Cancer -- Chemotherapy Ligands -- Toxicity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4394 , http://hdl.handle.net/10962/d1006009
- Description: Syntheses of Schiff bases were carried out by reacting salicylaldyhde, ortho-vanillin, para-vanillin or vanillin with aniline, 1-aminonaphthalene, 4- and 3-aminopyridine, and also with 2- and 3-aminomethylpyridine. The various Schiff bases obtained from the condensation reaction were reacted with CoCl₂.6H₂0, triethylamine stripped CoCl₂.6H₂0 or Co(CH₃COO)₂ to form cobalt(Il) complexes of ratio 2:1. The complexes obtained from cobalt chloride designated as the "A series" are of the general formulae ML₂X₂.nH₂0 , (L = Schiff base, X = chlorine) while those obtained from cobalt acetate or triethylamine stripped cobalt chloride denoted as "B" and C" are of the general formulae ML₂. nH₂0. The few complexes that do not follow the general formulae highlighted above are: IA [M(HL)₃.Cl₂], (L = N-phenylsalicylaldimine), 4A = (MLCl₂), (L = N-phenylvanaldiminato), 7 A and 21 A (ML₂), (L = N-naphthyl-o-vanaldiminato, and N-methy-2-pyridylsalicylaldiminato respectively), 8A = MLCI, (L = N-naphthylvanaldiminato), 12A = M₂L₃Cl₂, (L = N-4-pyridylvanaldiminato), 15A (MLCI), (L = N-3-pyridyl-o-vanaldiminato). The ligands and their complexes were characterized using elemental analyses and cobalt analysis using ICP, FT-IR spectroscopy (mid and far-IR), NIR-UV/vis (diffuse reflectance), UV/vis in an aprotic and a protic solvents, while mass spectrometry, ¹HNMR and ¹³CNMR, was used to further characterized the ligands. The tautomeric nature of the Schiff bases were determined by examining the behaviour of Schiff bases and their complexes in a protic (e.g. MeOH) and non-protic (e.g. DMF) polar solvents. The effects of solvents on the electronic behaviour of the compounds were also examined. Using CDCl₃, the NMR technique was further used to confirm the structures of the Schiff bases. The tentative geometry of the complexes was determined using the spectra information obtained from the far infrared and the diffuse reflectance spectroscopy. With few exceptions, most of the "A" series are tetrahedral or distorted tetrahedral, while the "B + C" are octahedral or pseudooctahedral. A small number of complexes are assigned square-planar geometry owing to the characteristic spectral behaviour shown. In order to determine their biological activity, two biological assay methods (antimicrobial testing and brine shrimp lethality assay) were used. Using disc method, the bacteriostatic and fungicidal activities of the various Schiff bases and their respective complexes to Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa as well as Aspergillus niger, were measured and the average inhibition zones are tabulated and analysed. Both the Schiff bases and their complexes showed varying bacteriostatic and fungicidal activity against the bacteria and fungus tested. The inhibition activity is concentration dependent and potential antibiotic and fungicides are identified. To determine the toxicity of the ligands and their corresponding cobalt(II) complexes, brine shrimp lethality assay was used. The LD₅₀ of the tested compounds were calculated and the results obtained were tabulated for comparison.
- Full Text:
- Date Issued: 2008
- Authors: Shaibu, Rafiu Olarewaju
- Date: 2008
- Subjects: Cobalt Schiff bases Artemia Spectrum analysis Ligands -- Analysis Bioinorganic chemistry Antineoplastic agents Cancer -- Chemotherapy Ligands -- Toxicity
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4394 , http://hdl.handle.net/10962/d1006009
- Description: Syntheses of Schiff bases were carried out by reacting salicylaldyhde, ortho-vanillin, para-vanillin or vanillin with aniline, 1-aminonaphthalene, 4- and 3-aminopyridine, and also with 2- and 3-aminomethylpyridine. The various Schiff bases obtained from the condensation reaction were reacted with CoCl₂.6H₂0, triethylamine stripped CoCl₂.6H₂0 or Co(CH₃COO)₂ to form cobalt(Il) complexes of ratio 2:1. The complexes obtained from cobalt chloride designated as the "A series" are of the general formulae ML₂X₂.nH₂0 , (L = Schiff base, X = chlorine) while those obtained from cobalt acetate or triethylamine stripped cobalt chloride denoted as "B" and C" are of the general formulae ML₂. nH₂0. The few complexes that do not follow the general formulae highlighted above are: IA [M(HL)₃.Cl₂], (L = N-phenylsalicylaldimine), 4A = (MLCl₂), (L = N-phenylvanaldiminato), 7 A and 21 A (ML₂), (L = N-naphthyl-o-vanaldiminato, and N-methy-2-pyridylsalicylaldiminato respectively), 8A = MLCI, (L = N-naphthylvanaldiminato), 12A = M₂L₃Cl₂, (L = N-4-pyridylvanaldiminato), 15A (MLCI), (L = N-3-pyridyl-o-vanaldiminato). The ligands and their complexes were characterized using elemental analyses and cobalt analysis using ICP, FT-IR spectroscopy (mid and far-IR), NIR-UV/vis (diffuse reflectance), UV/vis in an aprotic and a protic solvents, while mass spectrometry, ¹HNMR and ¹³CNMR, was used to further characterized the ligands. The tautomeric nature of the Schiff bases were determined by examining the behaviour of Schiff bases and their complexes in a protic (e.g. MeOH) and non-protic (e.g. DMF) polar solvents. The effects of solvents on the electronic behaviour of the compounds were also examined. Using CDCl₃, the NMR technique was further used to confirm the structures of the Schiff bases. The tentative geometry of the complexes was determined using the spectra information obtained from the far infrared and the diffuse reflectance spectroscopy. With few exceptions, most of the "A" series are tetrahedral or distorted tetrahedral, while the "B + C" are octahedral or pseudooctahedral. A small number of complexes are assigned square-planar geometry owing to the characteristic spectral behaviour shown. In order to determine their biological activity, two biological assay methods (antimicrobial testing and brine shrimp lethality assay) were used. Using disc method, the bacteriostatic and fungicidal activities of the various Schiff bases and their respective complexes to Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa as well as Aspergillus niger, were measured and the average inhibition zones are tabulated and analysed. Both the Schiff bases and their complexes showed varying bacteriostatic and fungicidal activity against the bacteria and fungus tested. The inhibition activity is concentration dependent and potential antibiotic and fungicides are identified. To determine the toxicity of the ligands and their corresponding cobalt(II) complexes, brine shrimp lethality assay was used. The LD₅₀ of the tested compounds were calculated and the results obtained were tabulated for comparison.
- Full Text:
- Date Issued: 2008
A bring your own device information security behavioural model
- Authors: Musarurwa, Alfred
- Date: 2017
- Subjects: Data protection Computer security -- Management Privacy, Right of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8587 , vital:33166
- Description: The Bring Your Own Device (BYOD) phenomenon has become prevalent in the modern-day workplace, including the banking industry. Employees who own devices have become the unintended administrators of the organisation’s information as their mobile devices often carry information belonging to the organisation. The unintended administrator is not necessarily schooled or aware of the information security risks and challenges that are associated with the BYOD. This inadvertently shifts the management of organisational information security from the information technology (IT) administrator to the unintended administrator. This shift leaves the organisation at risk of information security breaches that can permeate the organisation, which result from the behaviour that the unintended administrator displays when operating the mobile device. This study introduces the BYOD Information Security Behavioural (BISB) model. The model constructs are a combination of individual and organisational traits of the unintended administrator. The purpose of this study is to mitigate the risks posed by the unintended administrator in organisations through the implementation this model. The risk that the unintended administrator poses in relation to the BYOD phenomenon results in chief information officers (CIOs) being unable to totally control these mobile devices. Traditional endpoint information security management tools and methods can no longer secure devices in the BYOD the way they can in the traditional network where they are confined to the organisation’s IT administrator. This results in the organisation’s information security becoming the responsibility of the unintended administrator. This study was conducted in the banking sector in Zimbabwe. It is noteworthy that the BYOD phenomenon has become prevalent in the banking sector among other organisational sectors like education, health or even government departments. Information security is also an important component of the banks as such and a choice was made to conduct the study in the banking industry. The design science research paradigm was followed in this study and included a survey of 270 bank employees in Zimbabwe, which received 170 complete responses. A literature review on both employee behaviour and organisational culture was conducted, followed by a case study of a commercial bank in Zimbabwe. The literature review culminated in traits that were then classified as individual traits and organisational traits. Six constructs –, knowledge, attitude, habit, environment, governance and training – were identified from the literature and combined to form the BYOD information security behavioural (BISB) model. Statistical calculations were conducted on the survey results which informed the reliability, validity and rigour of the model constructs. An expert review including industry experts was conducted to evaluate the BISB model. This study concludes by recommending that organisations in Zimbabwe should make use of the BISB model to mitigate the information security risks that are posed by the unintended administrator. While there are technical solutions for managing the information security risks that come with the BYOD, this study points out that without harnessing the individual and organisational traits that make up the BYOD information security behavioural model for the unintended administrator, technical solutions alone will not be effective.
- Full Text:
- Date Issued: 2017
- Authors: Musarurwa, Alfred
- Date: 2017
- Subjects: Data protection Computer security -- Management Privacy, Right of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/8587 , vital:33166
- Description: The Bring Your Own Device (BYOD) phenomenon has become prevalent in the modern-day workplace, including the banking industry. Employees who own devices have become the unintended administrators of the organisation’s information as their mobile devices often carry information belonging to the organisation. The unintended administrator is not necessarily schooled or aware of the information security risks and challenges that are associated with the BYOD. This inadvertently shifts the management of organisational information security from the information technology (IT) administrator to the unintended administrator. This shift leaves the organisation at risk of information security breaches that can permeate the organisation, which result from the behaviour that the unintended administrator displays when operating the mobile device. This study introduces the BYOD Information Security Behavioural (BISB) model. The model constructs are a combination of individual and organisational traits of the unintended administrator. The purpose of this study is to mitigate the risks posed by the unintended administrator in organisations through the implementation this model. The risk that the unintended administrator poses in relation to the BYOD phenomenon results in chief information officers (CIOs) being unable to totally control these mobile devices. Traditional endpoint information security management tools and methods can no longer secure devices in the BYOD the way they can in the traditional network where they are confined to the organisation’s IT administrator. This results in the organisation’s information security becoming the responsibility of the unintended administrator. This study was conducted in the banking sector in Zimbabwe. It is noteworthy that the BYOD phenomenon has become prevalent in the banking sector among other organisational sectors like education, health or even government departments. Information security is also an important component of the banks as such and a choice was made to conduct the study in the banking industry. The design science research paradigm was followed in this study and included a survey of 270 bank employees in Zimbabwe, which received 170 complete responses. A literature review on both employee behaviour and organisational culture was conducted, followed by a case study of a commercial bank in Zimbabwe. The literature review culminated in traits that were then classified as individual traits and organisational traits. Six constructs –, knowledge, attitude, habit, environment, governance and training – were identified from the literature and combined to form the BYOD information security behavioural (BISB) model. Statistical calculations were conducted on the survey results which informed the reliability, validity and rigour of the model constructs. An expert review including industry experts was conducted to evaluate the BISB model. This study concludes by recommending that organisations in Zimbabwe should make use of the BISB model to mitigate the information security risks that are posed by the unintended administrator. While there are technical solutions for managing the information security risks that come with the BYOD, this study points out that without harnessing the individual and organisational traits that make up the BYOD information security behavioural model for the unintended administrator, technical solutions alone will not be effective.
- Full Text:
- Date Issued: 2017
A case for institutional investigations in economic research methods with reference to South Africa's agricultural sector
- Authors: Mbatha, Cyril
- Date: 2008
- Subjects: Economic development -- South Africa Economic development -- Research -- Methodology Agriculture -- South Africa Agriculture -- Economic aspects -- South Africa Agricultural productivity -- South Africa Agriculture -- Research -- South Africa South Africa -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:972 , http://hdl.handle.net/10962/d1002706
- Description: Economic development remains elusive for many world economies, but especially those of African countries. The current global inequalities in terms of GNP per capita and human living standards between developed and developing nations have ensured that the challenges of food insecurities are only some of the many negative experiences of underdevelopment in the African continent. Hence, delivery pressures are increasing on policy makers and researchers to provide tangible and timely economic solutions to the resilient state of underdevelopment. In the policy fights against the challenges posed by a lack of development in South Africa, the agricultural sector has in the past and continues in the present to play a central role. Such is the case because the majority of citizens rely on agricultural production activities for their livelihoods. For instance, even though the sector only contributed four percent towards the national Gross Domestic Product in 2006, in the Eastern Cape Province, more than seventy percent of the total population resided in rural areas. Moreover, in 2004 more than sixty percent of the national formal and informal employment levels were found in the sector. These economic indicators do not only reinforce the assertions that high levels of geographical and sectoral inequalities exist in the country’s economy, but they also illustrate the importance of the agricultural sector in public policy attempts, which are aimed at achieving food security alongside long-term developmental objectives. Some economists, especially the proponents of institutionalism, have argued that most of the recommendations to public policy interventions from mainstream economic research endeavours are not adequately helpful. The recommendations generally lack well considered and socially effective ideas, mainly because there remains some level of ignorance about the impacts that institutions have on economic and social systems. Some argue that this ignorance is reflected in (flawed) hedonistic and rationalist assumptions made about economic actors and in the methodological thinking of many research designs and economic analyses. The misuse of formal tools and statistical methods, for example, are some of the important factors, which have led to failures of the discipline of economics to provide effective policy solutions to problems of underdevelopment and poverty, especially in poor country environments. The thesis, having taken account of the majority of criticisms levelled against the classical and new-classical economic schools of thought, argues that the discipline as a whole lacks a paradigmatic integration of institutional and new-classical economic perspectives to offer appropriate guidelines for a methodology aimed at achieving socially responsive research outputs. The lack of this integration has resulted in a skewed selection of methods by economists, which are employed in research without a supportive and in-depth understanding of institutional and social factors. To support the thesis, a more effective and integrated framework for economic research is developed and presented with case study illustrations in a cumulative manner. The 20th century history of agricultural policies in South Africa, the agricultural and institutional case studies from the Eastern Cape Province alongside reviews of other agricultural studies are all used in presenting a case for rigorous institutional investigations in general economic research. These are also used in developing the proposed integrated framework, which aims to give guidance in developing research methods, which are more socially responsive. Having shown the usefulness of the proposed research framework, the thesis recommends that public policy interventions (at national and local levels) should aim to eliminate all types of institutions which have high associated transactional costs. The interventions should also encourage the emergence and growth of the types of institutions, which present the lowest costs to initiatives of economic development. In the primary case studies from the Eastern Cape Province, the insecurity of land tenure and the various local initiatives of business ventures are highlighted as two examples of the types of institutions, which respectively present high and low transactional costs to local initiatives of agricultural and economic development.
- Full Text:
- Date Issued: 2008
- Authors: Mbatha, Cyril
- Date: 2008
- Subjects: Economic development -- South Africa Economic development -- Research -- Methodology Agriculture -- South Africa Agriculture -- Economic aspects -- South Africa Agricultural productivity -- South Africa Agriculture -- Research -- South Africa South Africa -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:972 , http://hdl.handle.net/10962/d1002706
- Description: Economic development remains elusive for many world economies, but especially those of African countries. The current global inequalities in terms of GNP per capita and human living standards between developed and developing nations have ensured that the challenges of food insecurities are only some of the many negative experiences of underdevelopment in the African continent. Hence, delivery pressures are increasing on policy makers and researchers to provide tangible and timely economic solutions to the resilient state of underdevelopment. In the policy fights against the challenges posed by a lack of development in South Africa, the agricultural sector has in the past and continues in the present to play a central role. Such is the case because the majority of citizens rely on agricultural production activities for their livelihoods. For instance, even though the sector only contributed four percent towards the national Gross Domestic Product in 2006, in the Eastern Cape Province, more than seventy percent of the total population resided in rural areas. Moreover, in 2004 more than sixty percent of the national formal and informal employment levels were found in the sector. These economic indicators do not only reinforce the assertions that high levels of geographical and sectoral inequalities exist in the country’s economy, but they also illustrate the importance of the agricultural sector in public policy attempts, which are aimed at achieving food security alongside long-term developmental objectives. Some economists, especially the proponents of institutionalism, have argued that most of the recommendations to public policy interventions from mainstream economic research endeavours are not adequately helpful. The recommendations generally lack well considered and socially effective ideas, mainly because there remains some level of ignorance about the impacts that institutions have on economic and social systems. Some argue that this ignorance is reflected in (flawed) hedonistic and rationalist assumptions made about economic actors and in the methodological thinking of many research designs and economic analyses. The misuse of formal tools and statistical methods, for example, are some of the important factors, which have led to failures of the discipline of economics to provide effective policy solutions to problems of underdevelopment and poverty, especially in poor country environments. The thesis, having taken account of the majority of criticisms levelled against the classical and new-classical economic schools of thought, argues that the discipline as a whole lacks a paradigmatic integration of institutional and new-classical economic perspectives to offer appropriate guidelines for a methodology aimed at achieving socially responsive research outputs. The lack of this integration has resulted in a skewed selection of methods by economists, which are employed in research without a supportive and in-depth understanding of institutional and social factors. To support the thesis, a more effective and integrated framework for economic research is developed and presented with case study illustrations in a cumulative manner. The 20th century history of agricultural policies in South Africa, the agricultural and institutional case studies from the Eastern Cape Province alongside reviews of other agricultural studies are all used in presenting a case for rigorous institutional investigations in general economic research. These are also used in developing the proposed integrated framework, which aims to give guidance in developing research methods, which are more socially responsive. Having shown the usefulness of the proposed research framework, the thesis recommends that public policy interventions (at national and local levels) should aim to eliminate all types of institutions which have high associated transactional costs. The interventions should also encourage the emergence and growth of the types of institutions, which present the lowest costs to initiatives of economic development. In the primary case studies from the Eastern Cape Province, the insecurity of land tenure and the various local initiatives of business ventures are highlighted as two examples of the types of institutions, which respectively present high and low transactional costs to local initiatives of agricultural and economic development.
- Full Text:
- Date Issued: 2008
A case study : exploring a DVD driven approach for teaching and learning mathematics, at secondary school level, with a framework of blended learning
- Authors: Padayachee, Pragashni
- Date: 2010
- Subjects: Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10504 , http://hdl.handle.net/10948/1384 , Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Description: Post-apartheid South Africa is witnessing an education crisis of significant proportions. The new outcomes-based education system has failed to deliver and universities are suffering the consequences of under-preparation of learners for tertiary studies especially in mathematics. The educator corps is lacking and it has become common practice for universities to deploy augmented programmes in mathematics for secondary school learners in the surrounding areas. This thesis describes a particular approach of blended learning, devised for the Incubator School Project (ISP), an initiative of the Nelson Mandela Metropolitan University (NMMU) in the Eastern Cape of South Africa. The defining feature of this blended approach is that it incorporates DVD technology, which offers an affordable and accessible option for the particular group of learners and the schools they attend. The thesis poses the research question: How did the use of the DVD approach within a blended learning environment support the learning of mathematics? This case study explores the particular blended approach and reports six fold on the approach – qualitatively based firstly on a questionnaire completed by learners and secondly on interviews of learners, thirdly on the facilitators reports, fourthly quantitatively on learner performance before and after the intervention. Fifthly six schools are used as a case study where the mathematics performance of the learners who participated in the ISP is compared to those who did not participate in the ISP. Finally the scope of blending of this model is evaluated by means of a radar chart, adapted from an existing radar measure. This research revealed that using the DVD approach within a blended learning environment did lead to an improvement in learners perceptions about mathematics, an improvement in the manner in which they learned mathematics, an extension in their mathematics knowledge and provided learners with a supportive environment in which to learn mathematics. The elements which supported learning in this approach are presented. The findings of the study suggest that this approach impacted favourably on the mathematics learning and enhanced the mathematics learning and performance of these learners. Recommendations are offered for practice, teachers and schools and for further research possibilities.
- Full Text:
- Date Issued: 2010
- Authors: Padayachee, Pragashni
- Date: 2010
- Subjects: Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10504 , http://hdl.handle.net/10948/1384 , Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Description: Post-apartheid South Africa is witnessing an education crisis of significant proportions. The new outcomes-based education system has failed to deliver and universities are suffering the consequences of under-preparation of learners for tertiary studies especially in mathematics. The educator corps is lacking and it has become common practice for universities to deploy augmented programmes in mathematics for secondary school learners in the surrounding areas. This thesis describes a particular approach of blended learning, devised for the Incubator School Project (ISP), an initiative of the Nelson Mandela Metropolitan University (NMMU) in the Eastern Cape of South Africa. The defining feature of this blended approach is that it incorporates DVD technology, which offers an affordable and accessible option for the particular group of learners and the schools they attend. The thesis poses the research question: How did the use of the DVD approach within a blended learning environment support the learning of mathematics? This case study explores the particular blended approach and reports six fold on the approach – qualitatively based firstly on a questionnaire completed by learners and secondly on interviews of learners, thirdly on the facilitators reports, fourthly quantitatively on learner performance before and after the intervention. Fifthly six schools are used as a case study where the mathematics performance of the learners who participated in the ISP is compared to those who did not participate in the ISP. Finally the scope of blending of this model is evaluated by means of a radar chart, adapted from an existing radar measure. This research revealed that using the DVD approach within a blended learning environment did lead to an improvement in learners perceptions about mathematics, an improvement in the manner in which they learned mathematics, an extension in their mathematics knowledge and provided learners with a supportive environment in which to learn mathematics. The elements which supported learning in this approach are presented. The findings of the study suggest that this approach impacted favourably on the mathematics learning and enhanced the mathematics learning and performance of these learners. Recommendations are offered for practice, teachers and schools and for further research possibilities.
- Full Text:
- Date Issued: 2010
A case study of a pre-service mathematics education course to grow and develop proficient teaching in mathematics in the intermediate phase
- Authors: Lee, Amanda Jane
- Date: 2014
- Subjects: Mathematics -- Study and teaching -- South Africa , Mathematics teachers -- Training of -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2004 , http://hdl.handle.net/10962/d1015664
- Description: This research study investigated the ways in which a mathematics module, informed by an enactivist philosophy, enabled pre-service teachers to unpack the reality of their teaching practice in terms of proficient teaching. Given the generally poor mathematics results in South Africa it is not enough for teachers to be merely proficient in Mathematics. They also need to be in a position to explain important mathematical concepts to children in a manner that will encourage and develop an understanding of the basic mathematical concepts. It was my intention with this study to determine whether a mathematics education module, that embraced the underlying themes of enactivism as part of its teaching pedagogy, could have the potential to develop and increase the skills of pre-service teachers’ teaching for proficiency in Mathematics. The mathematics module was underpinned by five themes of enactivism namely: autonomy, embodiment, emergence, sense-making and experience and was designed to supplement the pre-service teachers’ basic skills in Mathematics in the Intermediate Phase. This mathematics module was offered to fourth year pre-service teachers completing a B.Ed. in the Foundation Phase at a private institute specialising in the training of teachers. The theoretical framework was informed by enactivism and how the themes of enactivism could be used as a vehicle to develop teaching proficiency. The study was qualitative in nature and situated within an interpretivist paradigm. The specific perspectives of interpretivism that were used were hermeneutics, phenomenology and reflexivity. The research design was a case study that contained elements of action research and encompassed three phases of data collection. The first phase focused on the pre-service teachers’ approach to teaching Mathematics and what this brought forth in terms of the reality of their teaching practice and the problems they encountered. The second phase undertook to determine what growth and development of teaching proficiency in Mathematics had emerged over the research period. The final phase was undertaken after the pre-service teachers had graduated and were employed as full time teachers in the Intermediate Phase. The analytical framework and lens through which the data was analysed was that of Kilpatrick, Swafford and Findell’s (2001) strands of mathematical proficiency. The argument that I present is that the themes of enactivism did contribute to the growth of the pre-service teachers’ teaching for mathematical proficiency. The themes of embodiment and experience were major contributions in revealing that this was a reality for the pre-service teachers from a practical perspective and was what they would be able to take away with them. However the theme of emergence stood out as the principle that generated the most awareness and growth and which, in turn, affected the participants’ autonomy.
- Full Text:
- Date Issued: 2014
- Authors: Lee, Amanda Jane
- Date: 2014
- Subjects: Mathematics -- Study and teaching -- South Africa , Mathematics teachers -- Training of -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2004 , http://hdl.handle.net/10962/d1015664
- Description: This research study investigated the ways in which a mathematics module, informed by an enactivist philosophy, enabled pre-service teachers to unpack the reality of their teaching practice in terms of proficient teaching. Given the generally poor mathematics results in South Africa it is not enough for teachers to be merely proficient in Mathematics. They also need to be in a position to explain important mathematical concepts to children in a manner that will encourage and develop an understanding of the basic mathematical concepts. It was my intention with this study to determine whether a mathematics education module, that embraced the underlying themes of enactivism as part of its teaching pedagogy, could have the potential to develop and increase the skills of pre-service teachers’ teaching for proficiency in Mathematics. The mathematics module was underpinned by five themes of enactivism namely: autonomy, embodiment, emergence, sense-making and experience and was designed to supplement the pre-service teachers’ basic skills in Mathematics in the Intermediate Phase. This mathematics module was offered to fourth year pre-service teachers completing a B.Ed. in the Foundation Phase at a private institute specialising in the training of teachers. The theoretical framework was informed by enactivism and how the themes of enactivism could be used as a vehicle to develop teaching proficiency. The study was qualitative in nature and situated within an interpretivist paradigm. The specific perspectives of interpretivism that were used were hermeneutics, phenomenology and reflexivity. The research design was a case study that contained elements of action research and encompassed three phases of data collection. The first phase focused on the pre-service teachers’ approach to teaching Mathematics and what this brought forth in terms of the reality of their teaching practice and the problems they encountered. The second phase undertook to determine what growth and development of teaching proficiency in Mathematics had emerged over the research period. The final phase was undertaken after the pre-service teachers had graduated and were employed as full time teachers in the Intermediate Phase. The analytical framework and lens through which the data was analysed was that of Kilpatrick, Swafford and Findell’s (2001) strands of mathematical proficiency. The argument that I present is that the themes of enactivism did contribute to the growth of the pre-service teachers’ teaching for mathematical proficiency. The themes of embodiment and experience were major contributions in revealing that this was a reality for the pre-service teachers from a practical perspective and was what they would be able to take away with them. However the theme of emergence stood out as the principle that generated the most awareness and growth and which, in turn, affected the participants’ autonomy.
- Full Text:
- Date Issued: 2014
A century of IsiXhosa written poetry and the ideological contest in South Africa
- Authors: Mona, Godfrey Vulindlela
- Date: 2015
- Subjects: Xhosa poetry -- History and criticism , Protest poetry, Xhosa , Ideology and literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3651 , http://hdl.handle.net/10962/d1017892
- Description: The central argument of this inter-disciplinary study is that IsiXhosa written poetry of 1912 – 2012 is a terrain of the struggle between the contending dominant ideologies of Segregation, Apartheid and Charterism (post-Apartheid); and the subordinate/ subaltern ideologies of Africanism, Charterism (pre-democracy), Pan- Africanism, Black Consciousness Movement and other post Apartheid ideologies. The study highlights the mutual relationship between the text and the context by focussing on the ideological contest which manifests itself in both form and structure (i.e. aesthetic ideology) and the content (i.e. authorial ideology) of the poetry of different epochs between 1912 and 2012. The study is located within the framework of Antonio Gramsci’s theory of cultural construction. Gramsci postulates that ideology and culture play a significant role in the process of asserting hegemony. Important concepts that constitute Gramsci’s theory of praxis are: ideology, culture, hegemony, organic intellectuals and both ideological and repressive state apparatuses. The first chapter presents the problem, the objectives, the methodology, and the scope of the study. The second chapter presents Gramsci’s theory of cultural construction and the work of scholars who developed his theory further. The tool that is employed for analysis and interpretation of textual significations of IsiXhosa written poetry is the revolutionary aesthetics, which is proposed by Udenta. The third chapter analyses and interprets literature of the epoch of 1912-1934 and exposes the contest between Segregation and Africanism ideologies. The fourth chapter contextualises and analyses the literature of 1934 – 1948, the second phase of contestation between Segregation and Africanism. The fifth chapter deals with literature of the first and second halves of the Apartheid epoch (1948 - 1973). The Apartheid ideology contested with the Africanist ideology which transformed into the Charterism ideology in 1955. In 1960 Pan-Africanism ideology and in 1969 Black Consciousness Movement ideologies entered the contest. The sixth chapter examines literature of the period 1973 – 1994 which is the second phase of the Apartheid epoch that ends with the “glasnost” period of 1990 - 1994. The seventh chapter studies literature of the democracy period of 1994 – 2012. The eighth chapter is the summary and general conclusion. The illumination of the nexus between culture and ideology during the past century (1912 - 2012) will provide insights that will assist us in addressing the challenges we face during the democracy period, and in the development on Arts and Culture in general, and literature in particular
- Full Text:
- Date Issued: 2015
- Authors: Mona, Godfrey Vulindlela
- Date: 2015
- Subjects: Xhosa poetry -- History and criticism , Protest poetry, Xhosa , Ideology and literature
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3651 , http://hdl.handle.net/10962/d1017892
- Description: The central argument of this inter-disciplinary study is that IsiXhosa written poetry of 1912 – 2012 is a terrain of the struggle between the contending dominant ideologies of Segregation, Apartheid and Charterism (post-Apartheid); and the subordinate/ subaltern ideologies of Africanism, Charterism (pre-democracy), Pan- Africanism, Black Consciousness Movement and other post Apartheid ideologies. The study highlights the mutual relationship between the text and the context by focussing on the ideological contest which manifests itself in both form and structure (i.e. aesthetic ideology) and the content (i.e. authorial ideology) of the poetry of different epochs between 1912 and 2012. The study is located within the framework of Antonio Gramsci’s theory of cultural construction. Gramsci postulates that ideology and culture play a significant role in the process of asserting hegemony. Important concepts that constitute Gramsci’s theory of praxis are: ideology, culture, hegemony, organic intellectuals and both ideological and repressive state apparatuses. The first chapter presents the problem, the objectives, the methodology, and the scope of the study. The second chapter presents Gramsci’s theory of cultural construction and the work of scholars who developed his theory further. The tool that is employed for analysis and interpretation of textual significations of IsiXhosa written poetry is the revolutionary aesthetics, which is proposed by Udenta. The third chapter analyses and interprets literature of the epoch of 1912-1934 and exposes the contest between Segregation and Africanism ideologies. The fourth chapter contextualises and analyses the literature of 1934 – 1948, the second phase of contestation between Segregation and Africanism. The fifth chapter deals with literature of the first and second halves of the Apartheid epoch (1948 - 1973). The Apartheid ideology contested with the Africanist ideology which transformed into the Charterism ideology in 1955. In 1960 Pan-Africanism ideology and in 1969 Black Consciousness Movement ideologies entered the contest. The sixth chapter examines literature of the period 1973 – 1994 which is the second phase of the Apartheid epoch that ends with the “glasnost” period of 1990 - 1994. The seventh chapter studies literature of the democracy period of 1994 – 2012. The eighth chapter is the summary and general conclusion. The illumination of the nexus between culture and ideology during the past century (1912 - 2012) will provide insights that will assist us in addressing the challenges we face during the democracy period, and in the development on Arts and Culture in general, and literature in particular
- Full Text:
- Date Issued: 2015
A classification of large wetlands in Africa’s elevated drylands based on their formation, structure, and hydrological functioning using Earth Observation (EO) data and Geographic Information System (GIS)
- Authors: Lidzhegu, Zwidofhelangani
- Date: 2020
- Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142668 , vital:38100
- Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
- Full Text:
- Date Issued: 2020
- Authors: Lidzhegu, Zwidofhelangani
- Date: 2020
- Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142668 , vital:38100
- Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
- Full Text:
- Date Issued: 2020
A collaboratively constructed process model for understanding and supporting the work of the community volunteer in a community school
- Authors: Damons, Bruce Peter
- Date: 2017
- Subjects: Volunteer workers in education -- South Africa Community schools -- South Africa , Volunteers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/15049 , vital:28116
- Description: This thesis sought to explore how community volunteers could be recruited, supported and sustained to assist a community school operating in difficult socioeconomic conditions in achieving basic school functionality. Through a collaborative process, the participants in the study attempted to address a significant gap in the literature, namely how this could be achieved in a way that would be beneficial both to the community volunteers and to the school itself. Based on existing literature, the vast majority of South African schools are struggling to reach the basic functionality levels required in terms of legislation. My interest in this topic was piqued while serving as principal of one such school; hence the focus in this thesis on whether schools would benefit in terms of achieving functionality if they partnered with the communities in which they are located. However, communities are seldom actively involved in the schools and school activities on an ongoing daily basis. In this thesis, I argue for an opportunity for schools and the community to collaborate in a way that would be mutually beneficial. In this, I was guided by the School-Based Complementary Learning Framework (SBCLF) in gaining a greater understanding of how multiple stakeholders could support a school to obtain basic functionality. A key stakeholder is the community in which a school is located, and the multidimensional framework provided a framework to understand why the community would want to get involved in the school. Following a Participatory Action Learning and Action Research (PALAR) design, I recruited 15 community volunteers from the existing pool at my then school; some of whom had been volunteering for over twelve years. We formed an action learning set where we collaboratively sought to understand the processes and conditions needed to recruit, support and sustain community volunteers and their involvement in the school. From this action learning set emerged a key advisors’ set, comprising five members of the action learning set, who were entrusted with the responsibility of planning, preparing and analysing the action learning set meetings. Transcripts and visual artefacts from the action learning set meetings and a focus group meeting of the school management team were analysed to generate data, complemented by secondary sources, such as documents. This participatory approach to data generation allowed the voice of every participant to be heard; agency was increased through active participation; and the sense of affiliation to the group was deepened. The iterative design of the research process further ensured that the participants also engaged in a critical discourse analysis of the emerging data, of which the trustworthiness was enhanced through the use of dialogic and process, catalytic, rhetoric, democratic and outcome validity. The emergence of the data through this collaborative engagement was underpinned by the ethical values of mutual respect; equality and inclusion; democratic participation; active learning; making a difference; collective action; and personal integrity. The findings revealed that community volunteers did add immense value to the school by supporting teaching and learning processes. However, the community volunteers also harboured expectations of material support and opportunities to develop skills. In addition, the study revealed that the hierarchical culture and structures present in most South African schools need to become more democratic and collaborative, with those working to make the school more functional, including community volunteers, being valued, acknowledged and supported. The participants also constructed their understanding of what a community school should be and do and how it should serve the interests of the children from the community. A process model was constructed from these findings regarding on ways to recruit, sustain and support community volunteers involved in community schools, specially designed so that schools could adapt it to suit individual contexts. This study is unique; I am not aware of any similar study ever having been conducted in a community school in South Africa. Furthermore, the collaborative approach used in the study helped ensure that the methodology used could be of value to principals and other school stakeholders in addressing the various complex challenges that confront schools in these contexts. Also, the findings will add to the theoretical body of knowledge around volunteerism, especially in difficult socioeconomic conditions.
- Full Text:
- Date Issued: 2017
- Authors: Damons, Bruce Peter
- Date: 2017
- Subjects: Volunteer workers in education -- South Africa Community schools -- South Africa , Volunteers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/15049 , vital:28116
- Description: This thesis sought to explore how community volunteers could be recruited, supported and sustained to assist a community school operating in difficult socioeconomic conditions in achieving basic school functionality. Through a collaborative process, the participants in the study attempted to address a significant gap in the literature, namely how this could be achieved in a way that would be beneficial both to the community volunteers and to the school itself. Based on existing literature, the vast majority of South African schools are struggling to reach the basic functionality levels required in terms of legislation. My interest in this topic was piqued while serving as principal of one such school; hence the focus in this thesis on whether schools would benefit in terms of achieving functionality if they partnered with the communities in which they are located. However, communities are seldom actively involved in the schools and school activities on an ongoing daily basis. In this thesis, I argue for an opportunity for schools and the community to collaborate in a way that would be mutually beneficial. In this, I was guided by the School-Based Complementary Learning Framework (SBCLF) in gaining a greater understanding of how multiple stakeholders could support a school to obtain basic functionality. A key stakeholder is the community in which a school is located, and the multidimensional framework provided a framework to understand why the community would want to get involved in the school. Following a Participatory Action Learning and Action Research (PALAR) design, I recruited 15 community volunteers from the existing pool at my then school; some of whom had been volunteering for over twelve years. We formed an action learning set where we collaboratively sought to understand the processes and conditions needed to recruit, support and sustain community volunteers and their involvement in the school. From this action learning set emerged a key advisors’ set, comprising five members of the action learning set, who were entrusted with the responsibility of planning, preparing and analysing the action learning set meetings. Transcripts and visual artefacts from the action learning set meetings and a focus group meeting of the school management team were analysed to generate data, complemented by secondary sources, such as documents. This participatory approach to data generation allowed the voice of every participant to be heard; agency was increased through active participation; and the sense of affiliation to the group was deepened. The iterative design of the research process further ensured that the participants also engaged in a critical discourse analysis of the emerging data, of which the trustworthiness was enhanced through the use of dialogic and process, catalytic, rhetoric, democratic and outcome validity. The emergence of the data through this collaborative engagement was underpinned by the ethical values of mutual respect; equality and inclusion; democratic participation; active learning; making a difference; collective action; and personal integrity. The findings revealed that community volunteers did add immense value to the school by supporting teaching and learning processes. However, the community volunteers also harboured expectations of material support and opportunities to develop skills. In addition, the study revealed that the hierarchical culture and structures present in most South African schools need to become more democratic and collaborative, with those working to make the school more functional, including community volunteers, being valued, acknowledged and supported. The participants also constructed their understanding of what a community school should be and do and how it should serve the interests of the children from the community. A process model was constructed from these findings regarding on ways to recruit, sustain and support community volunteers involved in community schools, specially designed so that schools could adapt it to suit individual contexts. This study is unique; I am not aware of any similar study ever having been conducted in a community school in South Africa. Furthermore, the collaborative approach used in the study helped ensure that the methodology used could be of value to principals and other school stakeholders in addressing the various complex challenges that confront schools in these contexts. Also, the findings will add to the theoretical body of knowledge around volunteerism, especially in difficult socioeconomic conditions.
- Full Text:
- Date Issued: 2017
A combination of a stationary and non-stationary model to predict corporate failure in South Africa
- Authors: Court, Philip Wathen
- Date: 1994
- Subjects: Bankruptcy -- South Africa Business planning -- South Africa Business failures -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1183 , http://hdl.handle.net/10962/d1002800
- Description: Business failure should be of concern in most industralised countries and the importance of accurately evaluating the phenomenon from a management and investment point of view is enormous. Were it possible to predict failure with a certain degree of confidence, steps could be taken to rectify the situation and the benefit would accrue to all of the stakeholders in the macroenvironment. In essence, the profitability of a business is influenced by two sets of variables. In the first instance, it is influenced by a variety of internal (microeconomic) variables which are firm- specific and which management is generally able to control. A further distinction in this regard may be made between the financial and non-financial variables. In the second instance, it is generally accepted that profitability will be influenced by a number of external (macroeconomic) variables which are generally beyond the control of management. In the main, however, the profitability of the firm is generally determined by a combination of both sets of factors. To date, a great deal of research has been undertaken in an attempt to establish a reliable model which may be used to predict failure. This has mainly been confined to the microeconomic variables which can be used to predict failure and attempts have been made to isolate either a single financial ratio or a number of financial and non-financial variables which can be used to model corporate failure. The research has met with a certain degree of success although this appears to be confined to the economic environment to which the models have been applied. The models are less successful when applied to other macroenvironments. Limited research has been undertaken into the macroeconomic variables which contribute to business failure or to a combination of the two types of variables. It is appropriate therefore that further consideration be given to the establishment of a model incorporating ALL the variables which could contribute to corporate failure. The purpose of this research is to undertake an investigation of micro- and macroeconomic variables that are freely available to reserachers and which may be used in a failure prediction model. The intention is to obtain a comprehensive, yet simple model which can be used as an overall predictor of PENDING failure.
- Full Text:
- Date Issued: 1994
- Authors: Court, Philip Wathen
- Date: 1994
- Subjects: Bankruptcy -- South Africa Business planning -- South Africa Business failures -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1183 , http://hdl.handle.net/10962/d1002800
- Description: Business failure should be of concern in most industralised countries and the importance of accurately evaluating the phenomenon from a management and investment point of view is enormous. Were it possible to predict failure with a certain degree of confidence, steps could be taken to rectify the situation and the benefit would accrue to all of the stakeholders in the macroenvironment. In essence, the profitability of a business is influenced by two sets of variables. In the first instance, it is influenced by a variety of internal (microeconomic) variables which are firm- specific and which management is generally able to control. A further distinction in this regard may be made between the financial and non-financial variables. In the second instance, it is generally accepted that profitability will be influenced by a number of external (macroeconomic) variables which are generally beyond the control of management. In the main, however, the profitability of the firm is generally determined by a combination of both sets of factors. To date, a great deal of research has been undertaken in an attempt to establish a reliable model which may be used to predict failure. This has mainly been confined to the microeconomic variables which can be used to predict failure and attempts have been made to isolate either a single financial ratio or a number of financial and non-financial variables which can be used to model corporate failure. The research has met with a certain degree of success although this appears to be confined to the economic environment to which the models have been applied. The models are less successful when applied to other macroenvironments. Limited research has been undertaken into the macroeconomic variables which contribute to business failure or to a combination of the two types of variables. It is appropriate therefore that further consideration be given to the establishment of a model incorporating ALL the variables which could contribute to corporate failure. The purpose of this research is to undertake an investigation of micro- and macroeconomic variables that are freely available to reserachers and which may be used in a failure prediction model. The intention is to obtain a comprehensive, yet simple model which can be used as an overall predictor of PENDING failure.
- Full Text:
- Date Issued: 1994
A combination of platinum anticancer drugs and mangiferin causes increased efficacy in cancer cell lines
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
A combinatorial analysis of barred preferential arrangements
- Authors: Nkonkobe, Sithembele
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/36228 , vital:24530
- Description: For a non-negative integer n an ordered partition of a set Xn with n distinct elements is called a preferential arrangement (PA). A barred preferential arrangement (BPA) is a preferential arrangement with bars in between the blocks of the partition. An integer sequence an associated with the counting PA's of Xn has been intensely studied over a century and a half in many different contexts. In this thesis we develop a unified combinatorial framework to study the enumeration of BPAs and a special subclass of BPAs. The results of the study lead to a positive settlement of an open problem and a conjecture by Nelsen. We derive few important identities pertaining to the number of BPAs and restricted BPAs of an n element set using generating- functionology. Later we show that the number of restricted BPAs of Xn are intricately related to well-known numbers such as Eulerian numbers, Bell numbers, Poly-Bernoulli numbers and the number of equivalence classes of fuzzy subsets of Xn under some equivalent relation.
- Full Text:
- Date Issued: 2016
- Authors: Nkonkobe, Sithembele
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/36228 , vital:24530
- Description: For a non-negative integer n an ordered partition of a set Xn with n distinct elements is called a preferential arrangement (PA). A barred preferential arrangement (BPA) is a preferential arrangement with bars in between the blocks of the partition. An integer sequence an associated with the counting PA's of Xn has been intensely studied over a century and a half in many different contexts. In this thesis we develop a unified combinatorial framework to study the enumeration of BPAs and a special subclass of BPAs. The results of the study lead to a positive settlement of an open problem and a conjecture by Nelsen. We derive few important identities pertaining to the number of BPAs and restricted BPAs of an n element set using generating- functionology. Later we show that the number of restricted BPAs of Xn are intricately related to well-known numbers such as Eulerian numbers, Bell numbers, Poly-Bernoulli numbers and the number of equivalence classes of fuzzy subsets of Xn under some equivalent relation.
- Full Text:
- Date Issued: 2016
A combined modelling approach for simulating channel–wetland exchanges in large African river basins
- Authors: Makungu, Eunice J
- Date: 2020
- Subjects: Watersheds -- Africa , Watershed management -- Africa , Water resources development -- Africa -- International cooperation , Floodplain management -- Africa , Wetland ecology -- Simulation methods -- Africa , Wetland management -- Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/123288 , vital:35424
- Description: In Africa, many large and extensive wetlands are hydrologically connected to rivers, and their environmental integrity, as well as their influence on downstream flow regimes, depends on the prevailing channel–wetland exchange processes. These processes are inherently complex and vary spatially and temporally. Understanding channel–wetland exchanges is therefore, indispensable for the effective management of wetlands and the associated river basins. However, this information is limited in most of the river basins containing large wetlands in Africa. Furthermore, it is important to understand the links between upstream and downstream flow regimes and the wetland dynamics themselves, specifically where there are water resource developments that may affect these links (upstream developments), or be affected by them (downstream developments). Hydrological modelling of the entire basin using basin-scale models that include wetland components in their structures can be used to provide the information required to manage water resources in such basins. However, the level of detail of wetland processes included in many basin-scale models is typically very low and the lack of understanding of the wetland dynamics makes it difficult to quantify the relevant parameters. Detailed hydraulic models represent the channel-wetland exchanges in a much more explicit manner, but require relatively more data and time resources to establish than coarser scale hydrological models. The main objective of this study was, therefore, to investigate the use of a detailed hydraulic wetland model to provide a better understanding of channel–wetland exchanges and wetland dynamics, and to use the results to improve the parameterisation of a basin-scale model. The study focused on improving the water resource assessments modelling of three data-scarce African river basins that contain large wetlands: the floodplains of the Luangwa and Upper Zambezi River basins and the Usangu wetland in the Upper Great Ruaha River basin. The overall objective was achieved through a combined modelling approach that uses a detailed high-resolution LISFLOOD-FP hydraulic model to inform the structure and parameters of the GW Pitman monthly hydrological model. The results from the LISFLOOD-FP were used to improve the understanding of the channel–wetland exchange dynamics and to establish the wetland parameters required in the GW Pitman model. While some wetland parameters were directly quantified from the LISFLOOD-FP model results, others, which are highly empirical, were estimated by manually calibrating the GW Pitman wetland sub-model implemented in excel spreadsheets containing the LISFLOOD-FP model results. Finally, the GW Pitman model with the inclusion of the estimated wetland parameters was applied for each basin and the results compared to the available downstream observed flow data. The two models have been successfully applied in southern Africa, with the GW Pitman model being one of the most widely applied hydrological models in this region. To address the issue of data scarcity, during setup of these models, the study mainly relied on the global datasets which clearly adds to the overall uncertainty of the modelling approach. However, this is a typical situation for most of the data scarce regions of the continent. A number of challenges were, however, faced during the setup of the LISFLOOD-FP, mainly due to the limitations of the data inputs. Some of the LISFLOOD-FP data inputs include boundary conditions (upstream and downstream), channel cross-sections and wetland topography. In the absence of observed daily flows to quantify the wetland upstream boundary conditions, monthly flow volumes simulated using the GW Pitman monthly model (without including the wetland sub-model) were disaggregated into daily flows using a disaggregation sub-model. The simulated wetland inflows were evaluated using the observed flow data for downstream gauging stations that include the wetland effects. The results highlighted that it is important to understand the possible impacts of each wetland on the downstream flow regime during the evaluations of the model simulation results. Although the disaggregation approach cannot be validated due to a lack of observed data, it at least enables the simulated monthly flows to be used in the daily time step hydraulic model. One of the recommendations is that improvements are required in gauging station networks to provide more observed information for the main river and the larger tributary inflows into these large and important wetland systems. Even a limited amount of newly observed data would be helpful to reduce some of the uncertainties in the combined modelling approach. The SRTM 90 m DEM (used to represent wetland topography) was filtered to reduce local variations and noise effects (mainly vegetation bias), but there were some pixels that falsely affect the inundation results, and the recently released vegetation-corrected DEMs are suggested to improve the simulation results. Channel cross-section values derived from global datasets should be examined because some widths estimated from the Andreadis et al. (2013) dataset were found to be over-generalised and did not reflect widths measured using high-resolution Google Earth in many places. There is an indication that channel cross-sections digitised from Google Earth images can be successfully used in the model setup except in densely vegetated swamps where the values are difficult to estimate, and in such situations, field measured cross-section data are required. Small channels such as those found in the Usangu wetland could play major role in the exchange dynamics, but digitising them all was not straightforward and only key ones were included in the model setup. Clearly, this inevitably introduced uncertainties in the simulated results, and future studies should consider applying methods that simplify extractions of most of these channels from high-resolution images to improve the simulated results. The study demonstrated that the wetland and channel physical characteristics, as well as the seasonal flow magnitude, largely influence the channel–wetland exchanges and wetland dynamics. The inundation results indicated that the area–storage and storage–inflow relationships form hysteretic curves, but the shape of these curves vary with flood magnitude and wetland type. Anticlockwise hysteresis curves were observed in both relationships for the floodplains (Luangwa and Barotse), whereas there appears to be no dominant curve type for the Usangu wetlands. The lack of well-defined hysteretic relationships in the Usangu could be related to some of the difficulties (and resulting uncertainties) that were experienced in setting up the model for this wetland. The storage–inflow relationships in all wetlands have quite complex rising limbs due to multiple flow peaks during the main wet season. The largest inundation area and storage volume for the Barotse and Usangu wetlands occurred after the peak discharge of the wet season, a result that is clearly related to the degree of connectivity between the main channel and those areas of the wetlands that are furthest away from the channel. Hysteresis effects were found to increase with an increase in flood magnitudes and temporal variations in the wetland inflows. Overall, hysteresis behaviour is common in large wetlands and it is recommended that hysteresis curves should be reflected in basin-scale modelling of large river basins with substantial wetland areas. At a daily time scale, inflow–outflow relationships showed a significant peak reduction and a delayed time to peak of several weeks in the Barotse and Usangu wetlands, whereas the attenuation effects of the Luangwa floodplain are minimal. To a large extent, the LISFLOOD-FP results provided useful information to establish wetland parameters and assess the structure of Pitman wetland sub-model. The simple spreadsheet used to estimate wetland parameters did not account for the wetland water transfers from the upstream to the next section downstream (the condition that is included in the LISFLOOD-FP model) for the case when the wetlands were distributed across more than one sub-basin. It is recommended that a method that allows for the upstream wetland inflows and the channel inflows should be included in the spreadsheet. The same is true to the Pitman model structure, and a downstream transfer of water can be modelled through return flows to the channel. The structure of the wetland sub-model was modified to allow an option for the return flows to occur at any time during the simulation period to provide for types of wetlands (e.g. the Luangwa) where spills from the channel and drainage back to the channel occur simultaneously. The setup of the GW Pitman model with the inclusion of wetland parameters improved the simulation results. However, the results for the Usangu wetlands were not very satisfactory and the collection of additional field data related to exchange dynamics is recommended to achieve improvements. The impacts of the Luangwa floodplain on the flow regime of the Luangwa River are very small at the monthly time scale, whereas the Barotse floodplain system and the Usangu wetlands extensively regulate flows of the Zambezi River and the Great Ruaha River, respectively. The results highlighted the possibilities of regionalising some wetland parameters using an understanding of wetland physical characteristics and their water exchange dynamics. However, some parameters remain difficult to quantify in the absence of site-specific information about the water exchange dynamics. The overall conclusion is that the approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins. This approach is not restricted to the two used models, as it can be applied using different model combinations to achieve similar study purpose.
- Full Text:
- Date Issued: 2020
A combined modelling approach for simulating channel–wetland exchanges in large African river basins
- Authors: Makungu, Eunice J
- Date: 2020
- Subjects: Watersheds -- Africa , Watershed management -- Africa , Water resources development -- Africa -- International cooperation , Floodplain management -- Africa , Wetland ecology -- Simulation methods -- Africa , Wetland management -- Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/123288 , vital:35424
- Description: In Africa, many large and extensive wetlands are hydrologically connected to rivers, and their environmental integrity, as well as their influence on downstream flow regimes, depends on the prevailing channel–wetland exchange processes. These processes are inherently complex and vary spatially and temporally. Understanding channel–wetland exchanges is therefore, indispensable for the effective management of wetlands and the associated river basins. However, this information is limited in most of the river basins containing large wetlands in Africa. Furthermore, it is important to understand the links between upstream and downstream flow regimes and the wetland dynamics themselves, specifically where there are water resource developments that may affect these links (upstream developments), or be affected by them (downstream developments). Hydrological modelling of the entire basin using basin-scale models that include wetland components in their structures can be used to provide the information required to manage water resources in such basins. However, the level of detail of wetland processes included in many basin-scale models is typically very low and the lack of understanding of the wetland dynamics makes it difficult to quantify the relevant parameters. Detailed hydraulic models represent the channel-wetland exchanges in a much more explicit manner, but require relatively more data and time resources to establish than coarser scale hydrological models. The main objective of this study was, therefore, to investigate the use of a detailed hydraulic wetland model to provide a better understanding of channel–wetland exchanges and wetland dynamics, and to use the results to improve the parameterisation of a basin-scale model. The study focused on improving the water resource assessments modelling of three data-scarce African river basins that contain large wetlands: the floodplains of the Luangwa and Upper Zambezi River basins and the Usangu wetland in the Upper Great Ruaha River basin. The overall objective was achieved through a combined modelling approach that uses a detailed high-resolution LISFLOOD-FP hydraulic model to inform the structure and parameters of the GW Pitman monthly hydrological model. The results from the LISFLOOD-FP were used to improve the understanding of the channel–wetland exchange dynamics and to establish the wetland parameters required in the GW Pitman model. While some wetland parameters were directly quantified from the LISFLOOD-FP model results, others, which are highly empirical, were estimated by manually calibrating the GW Pitman wetland sub-model implemented in excel spreadsheets containing the LISFLOOD-FP model results. Finally, the GW Pitman model with the inclusion of the estimated wetland parameters was applied for each basin and the results compared to the available downstream observed flow data. The two models have been successfully applied in southern Africa, with the GW Pitman model being one of the most widely applied hydrological models in this region. To address the issue of data scarcity, during setup of these models, the study mainly relied on the global datasets which clearly adds to the overall uncertainty of the modelling approach. However, this is a typical situation for most of the data scarce regions of the continent. A number of challenges were, however, faced during the setup of the LISFLOOD-FP, mainly due to the limitations of the data inputs. Some of the LISFLOOD-FP data inputs include boundary conditions (upstream and downstream), channel cross-sections and wetland topography. In the absence of observed daily flows to quantify the wetland upstream boundary conditions, monthly flow volumes simulated using the GW Pitman monthly model (without including the wetland sub-model) were disaggregated into daily flows using a disaggregation sub-model. The simulated wetland inflows were evaluated using the observed flow data for downstream gauging stations that include the wetland effects. The results highlighted that it is important to understand the possible impacts of each wetland on the downstream flow regime during the evaluations of the model simulation results. Although the disaggregation approach cannot be validated due to a lack of observed data, it at least enables the simulated monthly flows to be used in the daily time step hydraulic model. One of the recommendations is that improvements are required in gauging station networks to provide more observed information for the main river and the larger tributary inflows into these large and important wetland systems. Even a limited amount of newly observed data would be helpful to reduce some of the uncertainties in the combined modelling approach. The SRTM 90 m DEM (used to represent wetland topography) was filtered to reduce local variations and noise effects (mainly vegetation bias), but there were some pixels that falsely affect the inundation results, and the recently released vegetation-corrected DEMs are suggested to improve the simulation results. Channel cross-section values derived from global datasets should be examined because some widths estimated from the Andreadis et al. (2013) dataset were found to be over-generalised and did not reflect widths measured using high-resolution Google Earth in many places. There is an indication that channel cross-sections digitised from Google Earth images can be successfully used in the model setup except in densely vegetated swamps where the values are difficult to estimate, and in such situations, field measured cross-section data are required. Small channels such as those found in the Usangu wetland could play major role in the exchange dynamics, but digitising them all was not straightforward and only key ones were included in the model setup. Clearly, this inevitably introduced uncertainties in the simulated results, and future studies should consider applying methods that simplify extractions of most of these channels from high-resolution images to improve the simulated results. The study demonstrated that the wetland and channel physical characteristics, as well as the seasonal flow magnitude, largely influence the channel–wetland exchanges and wetland dynamics. The inundation results indicated that the area–storage and storage–inflow relationships form hysteretic curves, but the shape of these curves vary with flood magnitude and wetland type. Anticlockwise hysteresis curves were observed in both relationships for the floodplains (Luangwa and Barotse), whereas there appears to be no dominant curve type for the Usangu wetlands. The lack of well-defined hysteretic relationships in the Usangu could be related to some of the difficulties (and resulting uncertainties) that were experienced in setting up the model for this wetland. The storage–inflow relationships in all wetlands have quite complex rising limbs due to multiple flow peaks during the main wet season. The largest inundation area and storage volume for the Barotse and Usangu wetlands occurred after the peak discharge of the wet season, a result that is clearly related to the degree of connectivity between the main channel and those areas of the wetlands that are furthest away from the channel. Hysteresis effects were found to increase with an increase in flood magnitudes and temporal variations in the wetland inflows. Overall, hysteresis behaviour is common in large wetlands and it is recommended that hysteresis curves should be reflected in basin-scale modelling of large river basins with substantial wetland areas. At a daily time scale, inflow–outflow relationships showed a significant peak reduction and a delayed time to peak of several weeks in the Barotse and Usangu wetlands, whereas the attenuation effects of the Luangwa floodplain are minimal. To a large extent, the LISFLOOD-FP results provided useful information to establish wetland parameters and assess the structure of Pitman wetland sub-model. The simple spreadsheet used to estimate wetland parameters did not account for the wetland water transfers from the upstream to the next section downstream (the condition that is included in the LISFLOOD-FP model) for the case when the wetlands were distributed across more than one sub-basin. It is recommended that a method that allows for the upstream wetland inflows and the channel inflows should be included in the spreadsheet. The same is true to the Pitman model structure, and a downstream transfer of water can be modelled through return flows to the channel. The structure of the wetland sub-model was modified to allow an option for the return flows to occur at any time during the simulation period to provide for types of wetlands (e.g. the Luangwa) where spills from the channel and drainage back to the channel occur simultaneously. The setup of the GW Pitman model with the inclusion of wetland parameters improved the simulation results. However, the results for the Usangu wetlands were not very satisfactory and the collection of additional field data related to exchange dynamics is recommended to achieve improvements. The impacts of the Luangwa floodplain on the flow regime of the Luangwa River are very small at the monthly time scale, whereas the Barotse floodplain system and the Usangu wetlands extensively regulate flows of the Zambezi River and the Great Ruaha River, respectively. The results highlighted the possibilities of regionalising some wetland parameters using an understanding of wetland physical characteristics and their water exchange dynamics. However, some parameters remain difficult to quantify in the absence of site-specific information about the water exchange dynamics. The overall conclusion is that the approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins. This approach is not restricted to the two used models, as it can be applied using different model combinations to achieve similar study purpose.
- Full Text:
- Date Issued: 2020
A commentary on the eleventh book of the Punica of Silius Italicus
- Matier, K O (Kenneth Ogilvie)
- Authors: Matier, K O (Kenneth Ogilvie)
- Date: 1980
- Subjects: Silius Italicus, Tiberius Catius. Punica Latin literature -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3624 , http://hdl.handle.net/10962/d1007535
- Description: Preface: The scope of the commentary is limited. I have been concerned with establishing the diction of Silius in Book 11. I have shown which words are confined to epic, which words are poetic and which words are prosaic. I have not attempted to establish whether there is a correlation between Silius' use of 'poetic' and' prosaic' words and the content of what he is saying. But I have noticed that Silius frequently uses prosaic words when he is following Livy or some other historical source. In other cases, Silius may be using prosaic words because of his own training as an orator. He is clearly indebted to Cicero. Nor have I attempted to establish whether there is any particular effect when Silius uses a'poetic' or 'prosaic' word or phrase or construction. I have been influenced by considerations of length and also by the fact that I believe any such attempted interpretation, although it might produce valuable results, would of necessity be much more subjective than what I have actually done. I leave any such interpretation to future researchers of Silius.
- Full Text:
- Date Issued: 1980
- Authors: Matier, K O (Kenneth Ogilvie)
- Date: 1980
- Subjects: Silius Italicus, Tiberius Catius. Punica Latin literature -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3624 , http://hdl.handle.net/10962/d1007535
- Description: Preface: The scope of the commentary is limited. I have been concerned with establishing the diction of Silius in Book 11. I have shown which words are confined to epic, which words are poetic and which words are prosaic. I have not attempted to establish whether there is a correlation between Silius' use of 'poetic' and' prosaic' words and the content of what he is saying. But I have noticed that Silius frequently uses prosaic words when he is following Livy or some other historical source. In other cases, Silius may be using prosaic words because of his own training as an orator. He is clearly indebted to Cicero. Nor have I attempted to establish whether there is any particular effect when Silius uses a'poetic' or 'prosaic' word or phrase or construction. I have been influenced by considerations of length and also by the fact that I believe any such attempted interpretation, although it might produce valuable results, would of necessity be much more subjective than what I have actually done. I leave any such interpretation to future researchers of Silius.
- Full Text:
- Date Issued: 1980
A comparative analysis of the use of participatory practices by indigenous trusts and mainstream development NGOs in Zvimba Communal Area Zimbabwe
- Authors: Mbanje, Bowden Bolt
- Date: 2020
- Subjects: Caritas Zimbabwe , Zvimba Community Share Ownership Trust (ZvCSOT) , Non-governmental organizations -- Zimbabwe -- Zvimba District , Community development -- Zimbabwe -- Zvimba District , Rural development -- Zimbabwe -- Zvimba District , Zvimba Communal Land (Zimbabwe)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167099 , vital:41437
- Description: This thesis compares the extent to which participatory practices have been used by Caritas Zimbabwe, a mainstream NGO, and the Zvimba Community Share Ownership Trust (ZvCSOT), an indigenous Trust, in Zvimba District, Zimbabwe. Participatory development initiatives are common practice in NGO and government development work in Zimbabwe. The thesis begins with a discussion of two aspects of participatory development (PD). Firstly, PD is discussed in relation to decentralization processes where central government transfers administrative and financial authority to sub-national government units in order to enhance the participation of rural communities in development interventions. Secondly, PD is discussed in relation to the increased role of NGOs in development work. During the 1980s and 1990s, shifts in development thinking resulted in NGOs being perceived as important actors who could attend to the development gaps left by an economically incapacitated state. Both NGOs and sub-national government units were seen to be closer to rural communities and so were thought to be in a better position to enhance the participation of these communities in meaningful development projects. An analysis of the practices of the NGO and CSOT under consideration in this study shows that while there has been much rhetorical commitment to participation, community participation in the development interventions of the NGO and the CSOT is inadequate. In introducing and implementing development interventions, there has been a tendency by both the NGO and CSOT to give priority to organizational preferences over local needs. While recognizing the participatory efforts made by mainstream development NGOs (Caritas in particular) and indigenous Trusts (Zvimba Community Share Ownership Trust in particular) in Zimbabwe, this thesis also considers the impact of other factors on participatory development initiatives. A major observation from the study is that in as much as we expect genuine participatory approaches which include grassroots communities’ inputs from the project’s conceptualization all the way to its evaluation, the challenge is that the elites at the higher level (central government and donor offices) have their own development preferences and interests while the elites at the lower levels (local government and NGO offices) also have their own priorities and needs. Consequently, local communities tend to be confined to implementing development projects foisted on them by elites at the higher level as well as those at the lower level. Worse still, the study shows that elites at the lowest level (community) sometimes hijack or take advantage of the imposed projects. Participation has been stalled by elites at various levels of the participatory development ladder. Thus, unless power imbalances are seriously addressed at all levels, participatory development will remain elusive.
- Full Text:
- Date Issued: 2020
- Authors: Mbanje, Bowden Bolt
- Date: 2020
- Subjects: Caritas Zimbabwe , Zvimba Community Share Ownership Trust (ZvCSOT) , Non-governmental organizations -- Zimbabwe -- Zvimba District , Community development -- Zimbabwe -- Zvimba District , Rural development -- Zimbabwe -- Zvimba District , Zvimba Communal Land (Zimbabwe)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167099 , vital:41437
- Description: This thesis compares the extent to which participatory practices have been used by Caritas Zimbabwe, a mainstream NGO, and the Zvimba Community Share Ownership Trust (ZvCSOT), an indigenous Trust, in Zvimba District, Zimbabwe. Participatory development initiatives are common practice in NGO and government development work in Zimbabwe. The thesis begins with a discussion of two aspects of participatory development (PD). Firstly, PD is discussed in relation to decentralization processes where central government transfers administrative and financial authority to sub-national government units in order to enhance the participation of rural communities in development interventions. Secondly, PD is discussed in relation to the increased role of NGOs in development work. During the 1980s and 1990s, shifts in development thinking resulted in NGOs being perceived as important actors who could attend to the development gaps left by an economically incapacitated state. Both NGOs and sub-national government units were seen to be closer to rural communities and so were thought to be in a better position to enhance the participation of these communities in meaningful development projects. An analysis of the practices of the NGO and CSOT under consideration in this study shows that while there has been much rhetorical commitment to participation, community participation in the development interventions of the NGO and the CSOT is inadequate. In introducing and implementing development interventions, there has been a tendency by both the NGO and CSOT to give priority to organizational preferences over local needs. While recognizing the participatory efforts made by mainstream development NGOs (Caritas in particular) and indigenous Trusts (Zvimba Community Share Ownership Trust in particular) in Zimbabwe, this thesis also considers the impact of other factors on participatory development initiatives. A major observation from the study is that in as much as we expect genuine participatory approaches which include grassroots communities’ inputs from the project’s conceptualization all the way to its evaluation, the challenge is that the elites at the higher level (central government and donor offices) have their own development preferences and interests while the elites at the lower levels (local government and NGO offices) also have their own priorities and needs. Consequently, local communities tend to be confined to implementing development projects foisted on them by elites at the higher level as well as those at the lower level. Worse still, the study shows that elites at the lowest level (community) sometimes hijack or take advantage of the imposed projects. Participation has been stalled by elites at various levels of the participatory development ladder. Thus, unless power imbalances are seriously addressed at all levels, participatory development will remain elusive.
- Full Text:
- Date Issued: 2020
A comparative polarimetric study of the 43 GHz and 86 GHz SiO masers toward the supergiant star VY CMa
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
- Full Text:
- Date Issued: 2012
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
- Full Text:
- Date Issued: 2012
A comparative study of artificial neural networks and physics models as simulators in evolutionary robotics
- Pretorius, Christiaan Johannes
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
A comparative study of atmospheric dynamics in the mesosphere and lower thermosphere (MLT) near Grahamstown (South Africa) and Adelaide (Australia)
- Authors: Malinga, Sandile Bethuel
- Date: 2002
- Subjects: Atmospheric physics Atmospheric physics -- South Africa -- Eastern Cape Atmospheric physics -- Australia Dynamic meteorology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5506 , http://hdl.handle.net/10962/d1007307
- Description: The observations made near Grahamstown (33 .3°S, 26.5°E), South Africa and Adelaide (34.5°S, 138.5°E), Australia over the years 1987 to 1994 are used to study the dynamics of the mesosphere and lower thermosphere (ML T) region with a focus on ∼ 90 km altitude. In particular this thesis deals with on the atmospheric mean flow and the solar diurnal and semi diurnal oscillations with a view to (i) deducing their patterns at the two sites, (ii) comparing the dynamic structures observed at the two sites with special emphases on longitudinal variations, and (iii) putting these observations in a global context by comparing with other ground-based observations, satellite observations and numerical simulations. The main findings are summarised below. The mean flow and the tides at Grahamstown and Adelaide are characteristically variable at planetary time scales. Wavelet spectral and multiresolution analyses reveal that the dominant planetary oscillation is the quasi-16-day oscillation. However, no apparent correlation in the 16-day waves of the mean flow, the diurnal tide and the semidiurnal tide was found. The short-term fluctuations were also investigated using complex demodulation and bispectral techniques and it was found that some of the observed variations in tides could be due to non-linear wave-wave interactions. The long-term trends of the mean flow and tides show patterns that are in broad agreement with theory, results from elsewhere (ground-based and satellite) and the results of the Global-Scale Wave Model and various models by Portnyagin and others. In general the mean flow, the amplitudes and phases of both tides were found to exhibit seasonal and interannual variations which are thought to be related to various factors including (i) changes in the atmospheric mean environment, (ii) thermotidal forcing (iii) gravity wave effects, (iv) planetary scale influence, (v) long-term (e.g. quasi-biennial oscillation) modulation, and (vi) solar activity. There are significant longitudinal differences in the dynamic structure between Grahamstown and Adelaide. More especially, Grahamstown tends to have stronger mean flow and tidal activity than Adelaide. For tides, these differences are thought to be partly due to nonmigrating tidal modes but, in general, migrating modes were found to be dominant.
- Full Text:
- Date Issued: 2002
- Authors: Malinga, Sandile Bethuel
- Date: 2002
- Subjects: Atmospheric physics Atmospheric physics -- South Africa -- Eastern Cape Atmospheric physics -- Australia Dynamic meteorology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5506 , http://hdl.handle.net/10962/d1007307
- Description: The observations made near Grahamstown (33 .3°S, 26.5°E), South Africa and Adelaide (34.5°S, 138.5°E), Australia over the years 1987 to 1994 are used to study the dynamics of the mesosphere and lower thermosphere (ML T) region with a focus on ∼ 90 km altitude. In particular this thesis deals with on the atmospheric mean flow and the solar diurnal and semi diurnal oscillations with a view to (i) deducing their patterns at the two sites, (ii) comparing the dynamic structures observed at the two sites with special emphases on longitudinal variations, and (iii) putting these observations in a global context by comparing with other ground-based observations, satellite observations and numerical simulations. The main findings are summarised below. The mean flow and the tides at Grahamstown and Adelaide are characteristically variable at planetary time scales. Wavelet spectral and multiresolution analyses reveal that the dominant planetary oscillation is the quasi-16-day oscillation. However, no apparent correlation in the 16-day waves of the mean flow, the diurnal tide and the semidiurnal tide was found. The short-term fluctuations were also investigated using complex demodulation and bispectral techniques and it was found that some of the observed variations in tides could be due to non-linear wave-wave interactions. The long-term trends of the mean flow and tides show patterns that are in broad agreement with theory, results from elsewhere (ground-based and satellite) and the results of the Global-Scale Wave Model and various models by Portnyagin and others. In general the mean flow, the amplitudes and phases of both tides were found to exhibit seasonal and interannual variations which are thought to be related to various factors including (i) changes in the atmospheric mean environment, (ii) thermotidal forcing (iii) gravity wave effects, (iv) planetary scale influence, (v) long-term (e.g. quasi-biennial oscillation) modulation, and (vi) solar activity. There are significant longitudinal differences in the dynamic structure between Grahamstown and Adelaide. More especially, Grahamstown tends to have stronger mean flow and tidal activity than Adelaide. For tides, these differences are thought to be partly due to nonmigrating tidal modes but, in general, migrating modes were found to be dominant.
- Full Text:
- Date Issued: 2002
A comparative study of conceptualisations and practices of inclusion as an aspect of social justice in three teacher education institutions in Canada, South Africa and Zimbabwe
- Authors: Musara, Ellison
- Date: 2020
- Subjects: Social justice and education , Teachers -- Training of -- Canada , Teachers -- Training of -- South Africa , Teachers -- Training of -- Zimbabwe , Educational sociology -- Canada , Educational sociology -- South Africa , Educational sociology -- Zimbabwe , Educational equalization , Inclusive education , Education -- Moral and ethical aspects , Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/144138 , vital:38314
- Description: This study sought to examine understandings and practices of inclusion as social justice in teacher education programmes in three countries: Canada, South Africa and Zimbabwe. While inclusive education has become an issue of increasing importance globally, contemporary research shows that not much attention has been given to the preparation of teachers as a key element in developing inclusive education systems. Recognising that pre-service teacher education is vital to the success and continued development of inclusive educational practice, the purpose of this qualitative study was to better understand the ways in which inclusion is understood and practiced in the field of teacher education. Using Roy Bhaskar’s (1978) critical realism as a metatheory and drawing on Fraser’s substantive theory of social justice (2008, 2009) and Tronto’s ethic of care (1993, 2013), this study explored the extent to which teacher education faculty and teacher candidates understood and practiced inclusion as an aspect of social justice. The data used in this study was generated through individual and focus group interviews and document analysis in three higher education institutions, one in each of the three countries. In Canada, four teacher educators took part in the interviews while five teacher candidates participated in the focus group. Similarly, in South Africa, three teacher educators and eight teacher candidates participated, and in Zimbabwe, four teacher educators and eight teacher candidates took part in the study respectively. Findings from the study revealed that inclusion still means different things to different people, reflecting contrasting theoretical and ideological orientations from which inclusion is considered, while still remaining a major educational policy concern in all three countries. In the Canadian and South African institutions, inclusion is viewed more in terms of systemic educational change in pursuit of equity, social justice and equal educational opportunities for all learners. In the Zimbabwean institution, the primary focus of inclusion remains creating conditions that make it possible for students with disabilities to overcome barriers to learning and participation by providing specialist educational measures and interventions intended to respond to specific forms of impairment. As a comparative study, it is hoped that this study will contribute to the knowledge of variations and patterns in the ways in which inclusive education is shaped by societal forces such as political, economic and cultural conditions.
- Full Text:
- Date Issued: 2020
- Authors: Musara, Ellison
- Date: 2020
- Subjects: Social justice and education , Teachers -- Training of -- Canada , Teachers -- Training of -- South Africa , Teachers -- Training of -- Zimbabwe , Educational sociology -- Canada , Educational sociology -- South Africa , Educational sociology -- Zimbabwe , Educational equalization , Inclusive education , Education -- Moral and ethical aspects , Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/144138 , vital:38314
- Description: This study sought to examine understandings and practices of inclusion as social justice in teacher education programmes in three countries: Canada, South Africa and Zimbabwe. While inclusive education has become an issue of increasing importance globally, contemporary research shows that not much attention has been given to the preparation of teachers as a key element in developing inclusive education systems. Recognising that pre-service teacher education is vital to the success and continued development of inclusive educational practice, the purpose of this qualitative study was to better understand the ways in which inclusion is understood and practiced in the field of teacher education. Using Roy Bhaskar’s (1978) critical realism as a metatheory and drawing on Fraser’s substantive theory of social justice (2008, 2009) and Tronto’s ethic of care (1993, 2013), this study explored the extent to which teacher education faculty and teacher candidates understood and practiced inclusion as an aspect of social justice. The data used in this study was generated through individual and focus group interviews and document analysis in three higher education institutions, one in each of the three countries. In Canada, four teacher educators took part in the interviews while five teacher candidates participated in the focus group. Similarly, in South Africa, three teacher educators and eight teacher candidates participated, and in Zimbabwe, four teacher educators and eight teacher candidates took part in the study respectively. Findings from the study revealed that inclusion still means different things to different people, reflecting contrasting theoretical and ideological orientations from which inclusion is considered, while still remaining a major educational policy concern in all three countries. In the Canadian and South African institutions, inclusion is viewed more in terms of systemic educational change in pursuit of equity, social justice and equal educational opportunities for all learners. In the Zimbabwean institution, the primary focus of inclusion remains creating conditions that make it possible for students with disabilities to overcome barriers to learning and participation by providing specialist educational measures and interventions intended to respond to specific forms of impairment. As a comparative study, it is hoped that this study will contribute to the knowledge of variations and patterns in the ways in which inclusive education is shaped by societal forces such as political, economic and cultural conditions.
- Full Text:
- Date Issued: 2020