The incidence of musculoskeletal disorders and stakeholder perceptions of work challenges in South-Eastern Nigerian quarry mining industry
- Authors: Egwuonwu, Victor Afamerfuna
- Date: 2020
- Subjects: Quarries and quarrying -- Health aspects -- Nigeria , Musculoskeletal system -- Diseases -- Nigeria , Miners -- Health and hygiene -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141263 , vital:37957
- Description: Musculoskeletal disorders (MSDs) are very common among industrial labourers, leading to sick leave absence, disability and low productivity at work. MSDs have multifactorial causes, thereby making it difficult to pinpoint the extent of the contributions of the various risks regarding the mechanism of its pathophysiology. Previously, attempts were made to study regional pain symptoms in varying occupational groups, disregarding the particularities of the different workplace situations. It is important to highlight, that quantifying physical exposure factors that contribute to MSDs occurrence using quantitative approach alone could be inadequate. It is therefore imperative to incorporate qualitative approach to unmask accompanying psychosocial stressors, which are mostly explanatory variables. The study investigated the following: 12-month retrospective prevalence of MSDs, prospective incidence, risk factors and pattern of MSDs in a 6-month follow-up survey of selected quarry mineworkers, who reported MSDs complaints at the mine clinic. The study also determined the level of psychosocial stress associated with working in the mine by understanding stakeholders’ perception of work challenges, and how it influenced recurrence of MSDs. The study utilised a mixed method design with two phases: phase 1 was an initial baseline retrospective prevalence and a prospective cohort-control incidence survey. The Cultural and Psychosocial Influence on Disability (CUPID) questionnaire was translated into an Igbo-language version, cross-culturally adapted and utilized. The instrument was administered via oral interview and sought information on the following: demographic characteristics; pain in different anatomical sites and associated disability for tasks of daily living; as well as information on any change of job and reason during the study period, recent pain in different anatomical sites and associated disability for tasks of daily living; distress from common somatic symptoms; mental health status, sickness absence in the past 5-months for musculoskeletal pain. Phase 2 was a qualitative focus group discussion that engaged mine stakeholders on their perceptions of work challenges. Descriptive statistics of mean and standard deviation was utilised to analyse sociodemographic characteristics of participants. MSD incidence rates were estimated and the patterns of MSD incidence at different anatomical sites were also determined. The Cox proportional regression analyses were utilised to compare hazard ratios of MSD risks between the exposed cohorts and unexposed cohorts in the phase one incidence survey, alpha level was set at 0.05. Transcription, thematic and content analyses with the aid of Nvivo version 11 for windows was used to interpret stakeholders’ perception of work challenges. The incidence of MSD was 6.2 per 1000, with shoulder pain being the most reported complaint (40% prevalence). This was followed by back pain with the distribution of back pain presented as follows: upper back (20.37%), lower back (45.50%) and both (34.13%). All participants reported previous medical history of back, shoulder and neck pain. The relative risk ratio of mineworkers to MSDs was 4.57, which implies that the mineworkers were approximately 5 times more at risk of developing MSDs compared to the recruited unexposed cohorts. Meanwhile, wrist pain (43.58%) was the highest MSD complaints which lead miners to be absent from work, followed by knee and back with 35.42% and 21% respectively. Physical job risks, such as III working underground and squatting or kneeling at work were all significantly associated with MSDs recurrence in all six body parts (HR: 1.12-1.92, 95%CI). Similarly, time pressure to complete task, low decision latitude, poor job satisfaction, somatisation and mental disorder, job insecurity, poor incentive system (HR: 1.01-1.75, 95%CI) were perceived by stakeholders’ and participants alike in the study to be significantly associated with MSDs incidence. Quarrymen are exposed to high MSD risks associated with elevated psychosocial stress from their difficult work situations. The South Eastern Nigerian mine stakeholders believed that the high incidence of MSDs may have a substantial impact on health and productivity in the near future. Necessitating a clear need for the promotion of stakeholder’s engagement concerning safe work policy implementation initiatives in the sector.
- Full Text:
- Date Issued: 2020
- Authors: Egwuonwu, Victor Afamerfuna
- Date: 2020
- Subjects: Quarries and quarrying -- Health aspects -- Nigeria , Musculoskeletal system -- Diseases -- Nigeria , Miners -- Health and hygiene -- Nigeria
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141263 , vital:37957
- Description: Musculoskeletal disorders (MSDs) are very common among industrial labourers, leading to sick leave absence, disability and low productivity at work. MSDs have multifactorial causes, thereby making it difficult to pinpoint the extent of the contributions of the various risks regarding the mechanism of its pathophysiology. Previously, attempts were made to study regional pain symptoms in varying occupational groups, disregarding the particularities of the different workplace situations. It is important to highlight, that quantifying physical exposure factors that contribute to MSDs occurrence using quantitative approach alone could be inadequate. It is therefore imperative to incorporate qualitative approach to unmask accompanying psychosocial stressors, which are mostly explanatory variables. The study investigated the following: 12-month retrospective prevalence of MSDs, prospective incidence, risk factors and pattern of MSDs in a 6-month follow-up survey of selected quarry mineworkers, who reported MSDs complaints at the mine clinic. The study also determined the level of psychosocial stress associated with working in the mine by understanding stakeholders’ perception of work challenges, and how it influenced recurrence of MSDs. The study utilised a mixed method design with two phases: phase 1 was an initial baseline retrospective prevalence and a prospective cohort-control incidence survey. The Cultural and Psychosocial Influence on Disability (CUPID) questionnaire was translated into an Igbo-language version, cross-culturally adapted and utilized. The instrument was administered via oral interview and sought information on the following: demographic characteristics; pain in different anatomical sites and associated disability for tasks of daily living; as well as information on any change of job and reason during the study period, recent pain in different anatomical sites and associated disability for tasks of daily living; distress from common somatic symptoms; mental health status, sickness absence in the past 5-months for musculoskeletal pain. Phase 2 was a qualitative focus group discussion that engaged mine stakeholders on their perceptions of work challenges. Descriptive statistics of mean and standard deviation was utilised to analyse sociodemographic characteristics of participants. MSD incidence rates were estimated and the patterns of MSD incidence at different anatomical sites were also determined. The Cox proportional regression analyses were utilised to compare hazard ratios of MSD risks between the exposed cohorts and unexposed cohorts in the phase one incidence survey, alpha level was set at 0.05. Transcription, thematic and content analyses with the aid of Nvivo version 11 for windows was used to interpret stakeholders’ perception of work challenges. The incidence of MSD was 6.2 per 1000, with shoulder pain being the most reported complaint (40% prevalence). This was followed by back pain with the distribution of back pain presented as follows: upper back (20.37%), lower back (45.50%) and both (34.13%). All participants reported previous medical history of back, shoulder and neck pain. The relative risk ratio of mineworkers to MSDs was 4.57, which implies that the mineworkers were approximately 5 times more at risk of developing MSDs compared to the recruited unexposed cohorts. Meanwhile, wrist pain (43.58%) was the highest MSD complaints which lead miners to be absent from work, followed by knee and back with 35.42% and 21% respectively. Physical job risks, such as III working underground and squatting or kneeling at work were all significantly associated with MSDs recurrence in all six body parts (HR: 1.12-1.92, 95%CI). Similarly, time pressure to complete task, low decision latitude, poor job satisfaction, somatisation and mental disorder, job insecurity, poor incentive system (HR: 1.01-1.75, 95%CI) were perceived by stakeholders’ and participants alike in the study to be significantly associated with MSDs incidence. Quarrymen are exposed to high MSD risks associated with elevated psychosocial stress from their difficult work situations. The South Eastern Nigerian mine stakeholders believed that the high incidence of MSDs may have a substantial impact on health and productivity in the near future. Necessitating a clear need for the promotion of stakeholder’s engagement concerning safe work policy implementation initiatives in the sector.
- Full Text:
- Date Issued: 2020
Towards a Mobile Bioethanol Unit for point of source conversion of sugar sources to bioethanol: design and feasibility study for South Africa
- Authors: Cech, Alexandra Louise
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59141 , vital:27439
- Description: Restricted access-thesis embargoed for 5 years
- Full Text:
- Date Issued: 2015
- Authors: Cech, Alexandra Louise
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/59141 , vital:27439
- Description: Restricted access-thesis embargoed for 5 years
- Full Text:
- Date Issued: 2015
Naming in Germany in the 20th century: a sociological study of naming in times of social change, with a focus on statistical problems in empirical onomastic research
- Authors: Huschka, Denis
- Date: 2018
- Subjects: Onomastics , Names, Personal -- Germany , Names, German -- Etymology , Names, German -- Social aspects , German language -- Etymology -- Names , German Socio Economic Panel Study (SOEP)
- Language: German , English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63054 , vital:28359
- Description: In this thesis names are used as social indicators to observe social change in Germany in the 20th century. The German Socio Economic Panel Study (SOEP) offers the rare opportunity to analyse representative survey data of first names. The empirical results of the analyses in this thesis offer a comprehensive picture on how the naming reality in Germany looks like and how naming changed in a period of about 100 years. Names can serve as social indicators. It is demonstrated how chosen names mirror social change in the German society: Name choices have become less traditional and more individual. Over time names from other world regions and cultures have found their way into the German culture. There are more different names in use today than 100 years ago and the names have become more evenly distributed over the population. Today children are less likely to share their names with many of their peers. These are signs of an increasingly individualised, transnationalised modern behaviour of the people in contemporary Germany. Almost all of these developments started earlier and tend to be more pronounced for girl’s names. The secularisation of the German society - however - did not cause substantial changes in naming over time. Christian names still are used to the greatest extent, but – possibly – not because they are regarded as being of Christian origin. The analyses of the social-structural influences on naming touch on some effects of education and status. The analyses of differences in naming between the two German states during the time of division adds some evidence to the real-life experience that naming in the communist East Germany was much more oriented towards the free western hemisphere – a kind of silent protest. Obviously naming was a possibility to distance oneself from an un-loved regime. On a methodological level referring to onomastics, the so-called „Large Number of are Events-Zone (LNRE)“, a feature of the distribution of names that has mostly been handled inappropriately up to now, is discussed with respect to its effects on name statistics when using samples. An alternative approach is proposed for the appropriate handling of this feature. , In der vorliegenden Arbeit werden Vornamen als soziale Indikatoren benutzt, um gesellschaftlichen Wandel im 20. Jahrhundert zu beschreiben. Das Soziooekonomische Panel (SOEP) bietet die seltene Möglichkeit, Umfragedaten über die Vornamen der Deutschen repräsentativ auszuwerten. Die empirischen Ergebnisse der vorliegenden Arbeit bieten einen umfassenden Einblick in die deutsche Vornamensrealität und über die Entwicklungen der Namensvergabe in 100 Jahren. Namen sind soziale Indikatoren. Es wird aufgezeigt, wie die Namensgebung den sozialen Wandel in der deutschen Gesellschaft spiegelt: Namenwahlen weisen über die Zeit weniger traditionelle Bezüge auf, sie wurden individueller. Namen aus anderen Kulturen und Ländern fanden Eingang in die deutsche Kultur. Es werden mehr verschiedene Namen benutzt als vor 100 Jahren und die typischerweise hoch konzentrierten Verteilungen der Vornamen stellen sich über die Zeit etwas weniger konzentriert dar. Heute geborene Kinder teilen ihre Namen mit anteilig weniger anderen Kindern ihrer Kohorte. Dies sind Anzeichen für eine individualisierte, transnational orientierte moderne Gesellschaft. Fast alle dieser Entwicklungen sind für Mädchennamen früher und in deutlicherem Maße zu beobachten. Die Säkularisierung der deutschen Gesellschaft hat hingegen wenig Einfluss auf die Vornamenswahlen genommen. Nach wie vor werden vor allem christliche Namen vergeben, auch wenn der christliche Bezug unter Umständen nicht mehr der maßgebliche Grund für die Auswahl ist. Die Analyse der sozialstrukturellen Einflüsse auf Namenswahlen bestätigt einige Effekte von Bildung und Status der Mütter. Die Analyse der Unterschiede in der Namensgebung der beiden deutschen Staaten während der 40 jährigen Teilung zeigt, dass der lebensweltliche Eindruck einer zunehmenden West-Orientierung der Namenswahlen ostdeutscher Eltern nicht trügt. Offenbar waren westliche Namen eine Möglichkeit, sich vom ungeliebten Regime zu distanzieren. Auf einer statistisch-methodischen Ebene wird eine bislang in der empirischen Onomastik unrichtig gehandhabte Besonderheit von Vornamensverteilungen – die Large Number of Rare Events-Zone (LNRE) – diskutiert und Lösungsvorschläge für den statistisch korrekten Umgang mit dieser Besonderheit in Gruppenvergleichen auf der Basis von Stichproben vorgelegt.
- Full Text:
- Date Issued: 2018
- Authors: Huschka, Denis
- Date: 2018
- Subjects: Onomastics , Names, Personal -- Germany , Names, German -- Etymology , Names, German -- Social aspects , German language -- Etymology -- Names , German Socio Economic Panel Study (SOEP)
- Language: German , English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63054 , vital:28359
- Description: In this thesis names are used as social indicators to observe social change in Germany in the 20th century. The German Socio Economic Panel Study (SOEP) offers the rare opportunity to analyse representative survey data of first names. The empirical results of the analyses in this thesis offer a comprehensive picture on how the naming reality in Germany looks like and how naming changed in a period of about 100 years. Names can serve as social indicators. It is demonstrated how chosen names mirror social change in the German society: Name choices have become less traditional and more individual. Over time names from other world regions and cultures have found their way into the German culture. There are more different names in use today than 100 years ago and the names have become more evenly distributed over the population. Today children are less likely to share their names with many of their peers. These are signs of an increasingly individualised, transnationalised modern behaviour of the people in contemporary Germany. Almost all of these developments started earlier and tend to be more pronounced for girl’s names. The secularisation of the German society - however - did not cause substantial changes in naming over time. Christian names still are used to the greatest extent, but – possibly – not because they are regarded as being of Christian origin. The analyses of the social-structural influences on naming touch on some effects of education and status. The analyses of differences in naming between the two German states during the time of division adds some evidence to the real-life experience that naming in the communist East Germany was much more oriented towards the free western hemisphere – a kind of silent protest. Obviously naming was a possibility to distance oneself from an un-loved regime. On a methodological level referring to onomastics, the so-called „Large Number of are Events-Zone (LNRE)“, a feature of the distribution of names that has mostly been handled inappropriately up to now, is discussed with respect to its effects on name statistics when using samples. An alternative approach is proposed for the appropriate handling of this feature. , In der vorliegenden Arbeit werden Vornamen als soziale Indikatoren benutzt, um gesellschaftlichen Wandel im 20. Jahrhundert zu beschreiben. Das Soziooekonomische Panel (SOEP) bietet die seltene Möglichkeit, Umfragedaten über die Vornamen der Deutschen repräsentativ auszuwerten. Die empirischen Ergebnisse der vorliegenden Arbeit bieten einen umfassenden Einblick in die deutsche Vornamensrealität und über die Entwicklungen der Namensvergabe in 100 Jahren. Namen sind soziale Indikatoren. Es wird aufgezeigt, wie die Namensgebung den sozialen Wandel in der deutschen Gesellschaft spiegelt: Namenwahlen weisen über die Zeit weniger traditionelle Bezüge auf, sie wurden individueller. Namen aus anderen Kulturen und Ländern fanden Eingang in die deutsche Kultur. Es werden mehr verschiedene Namen benutzt als vor 100 Jahren und die typischerweise hoch konzentrierten Verteilungen der Vornamen stellen sich über die Zeit etwas weniger konzentriert dar. Heute geborene Kinder teilen ihre Namen mit anteilig weniger anderen Kindern ihrer Kohorte. Dies sind Anzeichen für eine individualisierte, transnational orientierte moderne Gesellschaft. Fast alle dieser Entwicklungen sind für Mädchennamen früher und in deutlicherem Maße zu beobachten. Die Säkularisierung der deutschen Gesellschaft hat hingegen wenig Einfluss auf die Vornamenswahlen genommen. Nach wie vor werden vor allem christliche Namen vergeben, auch wenn der christliche Bezug unter Umständen nicht mehr der maßgebliche Grund für die Auswahl ist. Die Analyse der sozialstrukturellen Einflüsse auf Namenswahlen bestätigt einige Effekte von Bildung und Status der Mütter. Die Analyse der Unterschiede in der Namensgebung der beiden deutschen Staaten während der 40 jährigen Teilung zeigt, dass der lebensweltliche Eindruck einer zunehmenden West-Orientierung der Namenswahlen ostdeutscher Eltern nicht trügt. Offenbar waren westliche Namen eine Möglichkeit, sich vom ungeliebten Regime zu distanzieren. Auf einer statistisch-methodischen Ebene wird eine bislang in der empirischen Onomastik unrichtig gehandhabte Besonderheit von Vornamensverteilungen – die Large Number of Rare Events-Zone (LNRE) – diskutiert und Lösungsvorschläge für den statistisch korrekten Umgang mit dieser Besonderheit in Gruppenvergleichen auf der Basis von Stichproben vorgelegt.
- Full Text:
- Date Issued: 2018
The current utility of oligonucleotide aptamers in targeting the MUC1 mucin tumour marker
- Authors: Flanagan, Shane Patrick
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62969 , vital:28348
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Flanagan, Shane Patrick
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62969 , vital:28348
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Statistical Analysis of the Radio-Interferometric Measurement Equation, a derived adaptive weighting scheme, and applications to LOFAR-VLBI observation of the Extended Groth Strip
- Authors: Bonnassieux, Etienne
- Date: 2019
- Subjects: Radio astronomy , Astrophysics , Astrophysics -- Instruments -- Calibration , Imaging systems in astronomy , Radio interferometers , Radio telescopes , Astronomy -- Observations
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93789 , vital:30942
- Description: J.R.R Tolkien wrote, in his Mythopoeia, that “He sees no stars who does not see them first, of living silver made that sudden burst, to flame like flowers beneath the ancient song”. In his defense of myth-making, he formulates the argument that the attribution of meaning is an act of creation - that “trees are not ‘trees’ until so named and seen” - and that this capacity for creation defines the human creature. The scientific endeavour, in this context, can be understood as a social expression of a fundamental feature of humanity, and from this endeavour flows much understanding. This thesis, one thread among many, focuses on the study of astronomical objects as seen by the radio waves they emit. What are radio waves? Electromagnetic waves were theorised by James Clerk Maxwell (Maxwell 1864) in his great theoretical contribution to modern physics, their speed matching the speed of light as measured by Ole Christensen R0mer and, later, James Bradley. It was not until Heinrich Rudolf Hertz’s 1887 experiment that these waves were measured in a laboratory, leading to the dawn of radio communications - and, later, radio astronomy. The link between radio waves and light was one of association: light is known to behave as a wave (Young double-slit experiment), with the same propagation speed as electromagnetic radiation. Light “proper” is also known to exist beyond the optical regime: Herschel’s experiment shows that when diffracted through a prism, sunlight warms even those parts of a desk which are not observed to be lit (first evidence of infrared light). The link between optical light and unseen electromagnetic radiation is then an easy step to make, and one confirmed through countless technological applications (e.g. optical fiber to name but one). And as soon as this link is established, a question immediately comes to the mind of the astronomer: what does the sky, our Universe, look like to the radio “eye”? Radio astronomy has a short but storied history: from Karl Jansky’s serendipitous observation of the centre of the Milky Way, which outshines our Sun in the radio regime, in 1933, to Grote Reber’s hand-built back-yard radio antenna in 1937, which successfully detected radio emission from the Milky Way itself, to such monumental projects as the Square Kilometer Array and its multiple pathfinders, it has led to countless discoveries and the opening of a truly new window on the Universe. The work presented in this thesis is a contribution to this discipline - the culmination of three years of study, which is a rather short time to get a firm grasp of radio interferometry both in theory and in practice. The need for robust, automated methods - which are improving daily, thanks to the tireless labour of the scientists in the field - is becoming ever stronger as the SKA approaches, looming large on the horizon; but even today, in the precursor era of LOFAR, MeerKAT and other pathfinders, it is keenly felt. When I started my doctorate, the sheer scale of the task at hand felt overwhelming - to actually be able to contribute to its resolution seemed daunting indeed! Thankfully, as the saying goes, no society sets for itself material goals which it cannot achieve. This thesis took place at an exciting time for radio interferometry: at the start of my doctorate, the LOFAR international stations were - to my knowledge - only beginning to be used, and even then, only tentatively; MeerKAT had not yet shown its first light; the techniques used throughout my work were still being developed. At the time of writing, great strides have been made. One of the greatest technical challenges of LOFAR - imaging using the international stations - is starting to become reality. This technical challenge is the key problem that this thesis set out to address. While we only achieved partial success so far, it is a testament to the difficulty of the task that it is not yet truly resolved. One of the major results of this thesis is a model of a bright resolved source near a famous extragalactic field: properly modeling this source not only allows the use of international LOFAR stations, but also grants deeper access to the extragalactic field itself, which is otherwise polluted by the 3C source’s sidelobes. This result was only achieved thanks to the other major result of this thesis: the development of a theoretical framework with which to better understand the effect of calibration errors on images made from interferometric data, and an algorithm to strongly mitigate them. The structure of this manuscript is as follows: we begin with an introduction to radio interferometry, LOFAR, and the emission mechanisms which dominate for our field of interest. These introductions are primarily intended to give a brief overview of the technical aspects of the data reduced in this thesis. We follow with an overview of the Measurement Equation formalism, which underpins our theoretical work. This is the keystone of this thesis. We then show the theoretical work that was developed as part of the research work done during the doctorate - which was published in Astronomy & Astrophysics. Its practical application - a quality-based weighting scheme - is used throughout our data reduction. This data reduction is the next topic of this thesis: we contextualise the scientific interest of the data we reduce, and explain both the methods and the results we achieve.
- Full Text:
- Date Issued: 2019
- Authors: Bonnassieux, Etienne
- Date: 2019
- Subjects: Radio astronomy , Astrophysics , Astrophysics -- Instruments -- Calibration , Imaging systems in astronomy , Radio interferometers , Radio telescopes , Astronomy -- Observations
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93789 , vital:30942
- Description: J.R.R Tolkien wrote, in his Mythopoeia, that “He sees no stars who does not see them first, of living silver made that sudden burst, to flame like flowers beneath the ancient song”. In his defense of myth-making, he formulates the argument that the attribution of meaning is an act of creation - that “trees are not ‘trees’ until so named and seen” - and that this capacity for creation defines the human creature. The scientific endeavour, in this context, can be understood as a social expression of a fundamental feature of humanity, and from this endeavour flows much understanding. This thesis, one thread among many, focuses on the study of astronomical objects as seen by the radio waves they emit. What are radio waves? Electromagnetic waves were theorised by James Clerk Maxwell (Maxwell 1864) in his great theoretical contribution to modern physics, their speed matching the speed of light as measured by Ole Christensen R0mer and, later, James Bradley. It was not until Heinrich Rudolf Hertz’s 1887 experiment that these waves were measured in a laboratory, leading to the dawn of radio communications - and, later, radio astronomy. The link between radio waves and light was one of association: light is known to behave as a wave (Young double-slit experiment), with the same propagation speed as electromagnetic radiation. Light “proper” is also known to exist beyond the optical regime: Herschel’s experiment shows that when diffracted through a prism, sunlight warms even those parts of a desk which are not observed to be lit (first evidence of infrared light). The link between optical light and unseen electromagnetic radiation is then an easy step to make, and one confirmed through countless technological applications (e.g. optical fiber to name but one). And as soon as this link is established, a question immediately comes to the mind of the astronomer: what does the sky, our Universe, look like to the radio “eye”? Radio astronomy has a short but storied history: from Karl Jansky’s serendipitous observation of the centre of the Milky Way, which outshines our Sun in the radio regime, in 1933, to Grote Reber’s hand-built back-yard radio antenna in 1937, which successfully detected radio emission from the Milky Way itself, to such monumental projects as the Square Kilometer Array and its multiple pathfinders, it has led to countless discoveries and the opening of a truly new window on the Universe. The work presented in this thesis is a contribution to this discipline - the culmination of three years of study, which is a rather short time to get a firm grasp of radio interferometry both in theory and in practice. The need for robust, automated methods - which are improving daily, thanks to the tireless labour of the scientists in the field - is becoming ever stronger as the SKA approaches, looming large on the horizon; but even today, in the precursor era of LOFAR, MeerKAT and other pathfinders, it is keenly felt. When I started my doctorate, the sheer scale of the task at hand felt overwhelming - to actually be able to contribute to its resolution seemed daunting indeed! Thankfully, as the saying goes, no society sets for itself material goals which it cannot achieve. This thesis took place at an exciting time for radio interferometry: at the start of my doctorate, the LOFAR international stations were - to my knowledge - only beginning to be used, and even then, only tentatively; MeerKAT had not yet shown its first light; the techniques used throughout my work were still being developed. At the time of writing, great strides have been made. One of the greatest technical challenges of LOFAR - imaging using the international stations - is starting to become reality. This technical challenge is the key problem that this thesis set out to address. While we only achieved partial success so far, it is a testament to the difficulty of the task that it is not yet truly resolved. One of the major results of this thesis is a model of a bright resolved source near a famous extragalactic field: properly modeling this source not only allows the use of international LOFAR stations, but also grants deeper access to the extragalactic field itself, which is otherwise polluted by the 3C source’s sidelobes. This result was only achieved thanks to the other major result of this thesis: the development of a theoretical framework with which to better understand the effect of calibration errors on images made from interferometric data, and an algorithm to strongly mitigate them. The structure of this manuscript is as follows: we begin with an introduction to radio interferometry, LOFAR, and the emission mechanisms which dominate for our field of interest. These introductions are primarily intended to give a brief overview of the technical aspects of the data reduced in this thesis. We follow with an overview of the Measurement Equation formalism, which underpins our theoretical work. This is the keystone of this thesis. We then show the theoretical work that was developed as part of the research work done during the doctorate - which was published in Astronomy & Astrophysics. Its practical application - a quality-based weighting scheme - is used throughout our data reduction. This data reduction is the next topic of this thesis: we contextualise the scientific interest of the data we reduce, and explain both the methods and the results we achieve.
- Full Text:
- Date Issued: 2019
“Munhu wese ihama yako (everyone is your relative)”: Ubuntu and the social inclusion of students with disabilities at South African universities
- Authors: Chiwandire, Desire
- Date: 2021
- Subjects: College students with disabilities -- Education -- South Africa , Inclusive education -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/170578 , vital:41938 , 10.21504/10962/170578
- Description: Background: During apartheid, South African students with disabilities (SWDs) were educated in special schools and taught an inferior curriculum. Black learners with disabilities were discriminated against on grounds of both race and disability. Following South Africa’s first democratic election in 1994, the African National Congress (ANC) government put in place arrange of new laws to address the educational and other needs of those disadvantaged under apartheid, including persons with disabilities (PWDs). The South African government is a signatory of the 2006 United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) which has resulted in the country assuming obligations to promote inclusive education for ASWDs. However, research (see, for instance, Chiwandire & Vincent 2019; Chiwandire 2019; Mutanga 2019; Majoko & Phasha 2018; Mutanga et al. 2018; Mutanga 2017a; Chiwandire 2017; Israel 2017) has shown that SWDs continue to fare differently in comparison to their non-disabled peers in terms of participation in education with the likelihood of success. Higher education institutions (HEIs) have thus been urged to create conducive environments for the academic inclusion of SWDs with particular attention being paid to lecturers employing inclusive instructional strategies as well as flexible curricula, if they are to ensure the equal opportunity for academic success of SWDs in the regular classroom setting. The focus, to date, on academic inclusion, while important, has meant that issues relating to the social inclusion of SWDs have received minimal attention. Purpose: To date, there is a dearth of South African studies which have investigated the social inclusion needs of SWDs on South African campuses. Although a number of studies have given voice to the perspectives of SWDs and lecturers, with respect to their experiences in relation to matters of academic inclusion in South African higher education (HE), few have focused on Disability Unit Staff Members(DUSMs) who are pivotal to ensuring fair and equitable policies and practices for SWDs in HEIs. Disability Studies (DS) as a field has been criticised for being dominated by voices from the Global North, which fail to consider or effectively theorise Global South disability experiences in a contextually relevant way. The thesis argues that the failure to recognise the value of diversity and to treat SWDs as valued and welcomed participants in South African HEIs partly stems from policy, practice and relationships being informed by the Western individualist paradigm that prizes individual achievement and success rather than cooperation and mutuality. The African philosophy of Ubuntu, which stresses values of communalism, hospitality and respect for human dignity is offered here as an alternative starting point for achieving genuinely inclusive campuses. Methods: In-depth face-to-face qualitative interviews were conducted with 40 participants, most of whom were, at the time of being interviewed, Heads of Disability Units and DUSMs based at 10 different universities in four of South Africa’s nine provinces. Data were coded and analysed using Braun & Clarke’s (2006) method of inductive and deductive thematic analysis. Results: The findings of this study indicate that South African campuses are ableist spaces in which the social needs of SWDs are not prioritised. The thesis argues that in order for campuses to become genuinely inclusive, South African campuses ought to seek to inculcate in their members the values of the African worldview Ubuntu, in contrast to the dominant Western individualist orthodoxy. SWDs are being excluded and denied a sense of belonging and equal participation despite universities giving lip service to embracing such inclusive education-oriented values as co-operative learning. Non-disabled students steeped in Western individualism, which affirms the solitary pursuit of individual success rather than the value of interdependence and diversity, end up marginalising SWDs who are seen as less capable. DUSMs addressing the needs of SWDs through an ableist/Western individualist lens are not challenging unfair practices which are impairing the dignity of SWDs, particularly students with physical disabilities who are being forced to “fit into” oppressive inaccessible built environments on campuses. These DUSMs may unwittingly re-inscribe ableist assumptions that normalise discrimination against SWDs. Conclusions and Recommendations: Ubuntu values offer a starting point for building mutual respect and interdependence between SWDs and their non-disabled peers. The thesis finds however that as was the case in traditional African communities, which embraced the values of Ubuntu, acts of leadership are required if Ubuntu’s values of human dignity, mutual respect and acceptance are to be fostered on campuses. In a range of important ways, the dignity of SWDs is not respected at HEIs in South Africa. This includes, for example, such practical matters as the inaccessibility of toilets to wheelchair users and the lack of appropriate signage for blind students. Disrespectful attitudes and assumptions about SWDs on the part of non-disabled university members also result in SWDs’ human dignity being impaired. Ubuntu’s value of hospitality stresses the importance of promoting relations of group solidarity and interdependence between SWDs and their non-disabled peers. Both academic inclusion-oriented programmes and the promotion of a wide range of social activities, involving both SWDs and non-disabled students, can play an important role in cultivating the formation of long-term fruitful and respectful friendships between SWDs and non-disabled students. An enabling classroom environment alone is not enough to holistically address the social inclusion needs of SWDs. South African HEIs that embrace the Ubuntu values of communalism, human dignity and hospitality will be in a position to respect the needs of SWDs as “whole persons”. Amongst other things, this requires DUSMs to be fully empowered to make important decisions regarding vital matters such as disability inclusion, and it necessitates university management to relinquish their power, so that they may work collaboratively with DUSMs and SWDs, all on equal footing, to ensure that HE funding allocation, policy and planning also prioritises the social needs of SWDs.
- Full Text:
- Date Issued: 2021
- Authors: Chiwandire, Desire
- Date: 2021
- Subjects: College students with disabilities -- Education -- South Africa , Inclusive education -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/170578 , vital:41938 , 10.21504/10962/170578
- Description: Background: During apartheid, South African students with disabilities (SWDs) were educated in special schools and taught an inferior curriculum. Black learners with disabilities were discriminated against on grounds of both race and disability. Following South Africa’s first democratic election in 1994, the African National Congress (ANC) government put in place arrange of new laws to address the educational and other needs of those disadvantaged under apartheid, including persons with disabilities (PWDs). The South African government is a signatory of the 2006 United Nations Convention on the Rights of Persons with Disabilities (UNCRPD) which has resulted in the country assuming obligations to promote inclusive education for ASWDs. However, research (see, for instance, Chiwandire & Vincent 2019; Chiwandire 2019; Mutanga 2019; Majoko & Phasha 2018; Mutanga et al. 2018; Mutanga 2017a; Chiwandire 2017; Israel 2017) has shown that SWDs continue to fare differently in comparison to their non-disabled peers in terms of participation in education with the likelihood of success. Higher education institutions (HEIs) have thus been urged to create conducive environments for the academic inclusion of SWDs with particular attention being paid to lecturers employing inclusive instructional strategies as well as flexible curricula, if they are to ensure the equal opportunity for academic success of SWDs in the regular classroom setting. The focus, to date, on academic inclusion, while important, has meant that issues relating to the social inclusion of SWDs have received minimal attention. Purpose: To date, there is a dearth of South African studies which have investigated the social inclusion needs of SWDs on South African campuses. Although a number of studies have given voice to the perspectives of SWDs and lecturers, with respect to their experiences in relation to matters of academic inclusion in South African higher education (HE), few have focused on Disability Unit Staff Members(DUSMs) who are pivotal to ensuring fair and equitable policies and practices for SWDs in HEIs. Disability Studies (DS) as a field has been criticised for being dominated by voices from the Global North, which fail to consider or effectively theorise Global South disability experiences in a contextually relevant way. The thesis argues that the failure to recognise the value of diversity and to treat SWDs as valued and welcomed participants in South African HEIs partly stems from policy, practice and relationships being informed by the Western individualist paradigm that prizes individual achievement and success rather than cooperation and mutuality. The African philosophy of Ubuntu, which stresses values of communalism, hospitality and respect for human dignity is offered here as an alternative starting point for achieving genuinely inclusive campuses. Methods: In-depth face-to-face qualitative interviews were conducted with 40 participants, most of whom were, at the time of being interviewed, Heads of Disability Units and DUSMs based at 10 different universities in four of South Africa’s nine provinces. Data were coded and analysed using Braun & Clarke’s (2006) method of inductive and deductive thematic analysis. Results: The findings of this study indicate that South African campuses are ableist spaces in which the social needs of SWDs are not prioritised. The thesis argues that in order for campuses to become genuinely inclusive, South African campuses ought to seek to inculcate in their members the values of the African worldview Ubuntu, in contrast to the dominant Western individualist orthodoxy. SWDs are being excluded and denied a sense of belonging and equal participation despite universities giving lip service to embracing such inclusive education-oriented values as co-operative learning. Non-disabled students steeped in Western individualism, which affirms the solitary pursuit of individual success rather than the value of interdependence and diversity, end up marginalising SWDs who are seen as less capable. DUSMs addressing the needs of SWDs through an ableist/Western individualist lens are not challenging unfair practices which are impairing the dignity of SWDs, particularly students with physical disabilities who are being forced to “fit into” oppressive inaccessible built environments on campuses. These DUSMs may unwittingly re-inscribe ableist assumptions that normalise discrimination against SWDs. Conclusions and Recommendations: Ubuntu values offer a starting point for building mutual respect and interdependence between SWDs and their non-disabled peers. The thesis finds however that as was the case in traditional African communities, which embraced the values of Ubuntu, acts of leadership are required if Ubuntu’s values of human dignity, mutual respect and acceptance are to be fostered on campuses. In a range of important ways, the dignity of SWDs is not respected at HEIs in South Africa. This includes, for example, such practical matters as the inaccessibility of toilets to wheelchair users and the lack of appropriate signage for blind students. Disrespectful attitudes and assumptions about SWDs on the part of non-disabled university members also result in SWDs’ human dignity being impaired. Ubuntu’s value of hospitality stresses the importance of promoting relations of group solidarity and interdependence between SWDs and their non-disabled peers. Both academic inclusion-oriented programmes and the promotion of a wide range of social activities, involving both SWDs and non-disabled students, can play an important role in cultivating the formation of long-term fruitful and respectful friendships between SWDs and non-disabled students. An enabling classroom environment alone is not enough to holistically address the social inclusion needs of SWDs. South African HEIs that embrace the Ubuntu values of communalism, human dignity and hospitality will be in a position to respect the needs of SWDs as “whole persons”. Amongst other things, this requires DUSMs to be fully empowered to make important decisions regarding vital matters such as disability inclusion, and it necessitates university management to relinquish their power, so that they may work collaboratively with DUSMs and SWDs, all on equal footing, to ensure that HE funding allocation, policy and planning also prioritises the social needs of SWDs.
- Full Text:
- Date Issued: 2021
Studies in leaf domatia-mite mutualism in South Africa
- Authors: Situngu, Sivuyisiwe
- Date: 2018
- Subjects: Insect-plant relationships , Mites , Mutualism (Biology) , Biological pest control agents
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63334 , vital:28394
- Description: Plants have various traits which allow them to cope and resist their enemies including both insects and fungi . In some cases such traits allow plants to build mutualistic relationships with natural enemies of plant pests. This is the case in many dicotyledonous plants which produce leaf domatia. Leaf domatia are plant cavities usually found in the axils of major veins in the abaxial side of leaves. They are usually associated with mites and often mediate mutualistic relationships with predacious mites. Mites use leaf domatia primarily for shelter, to reproduce, and to develop. In turn, plants benefit from having predaceous mites on their leaves, because mites act as plant “bodyguards” and offer defence against pathogens and small arthropod herbivores. This phenomenon has been well documented all over the world, but Africa remains disproportionally understudied. The aim of this study was to fill the gap that exists in our knowledge of the extent of the distribution of leaf domatia-mite mutualisms and generate a better understanding of the diversity of mites found within leaf domatia from an African perspective. This was done by surveying plant species that bear leaf domatia from different vegetation types in South Africa. The plants with leaf domatia were examined for the presence of mites in order to determine patterns of mite abundance and diversity and, in so doing, address the following questions: • Does each tree species host have a specific mite or mite assemblage? • Do some mites prefer certain types of leaf domatia? • Do mites prefer a specific place in the tree canopy and does the microclimate in the tree canopy affect the distribution of mites? • Do different vegetation sites and types differ in their mite diversity and species composition? • Does mite abundance and diversity vary with seasons? Do coffee plantations have a different suite of mites than the adjacent forest? The anatomical structures of leaf domatia from six selected plant species(Coffea arabica, Gardenia thunbergia, Rothmannia capensis, Rothmannia globosa (Rubiaceae), Ocotea bullata (Lauraceae) and Tecoma capensis (Bignoniaceae) with different types of leaf domatia were also studied. The results from this study suggested that the key futures which distinguish domatia are the presence of an extra layer of tissue in the lower epidermis, a thick cuticle, cuticular folds, the presence of trichomes and an invagination. This study provides a better understating of the structure of leaf domatia. Leaf domatia bearing plants are widely distributed in South Africa, and species and vegetation-specific associations were assessed. Over 250 plant specimens with leaf domatia were collected and examined and more than 60 different mite species were found in association with the sampled plant species. The majority of mites found within the domatia of these tree species were predaceous and included mites from Stigmatidae, Tydeidae and Phytoseiidae. Furthermore, 15 new species were collected, suggesting that mites are understudied in South Africa. This study showed that the different vegetation types sampled did not differ markedly in terms of their mite biota and that similar mites were found across the region, and the association between leaf domatia and mites was found to be opportunistic and that mites had no preference for any particular domatia types. No host specificity relationship was observed between plants and mites. The assessment of mites associated with Coffea arabica showed that indigenous mites are able to colonise and establish a beneficial mutualism on exotic species. This is important as it ascertains that economically important plants that are cultivated outside their area of natural distribution can still benefit from this mutualism. This study also found that mite abundance and diversity in plants with leaf domatia were influenced by factors such as temperature, relative humidity and rainfall. Mite communities found in association with domatia changed as the year progressed and over the seasons. The seasonal fluctuations varied between the sampled plant species. In addition, this study found that mites were sensitive to extreme environmental conditions, and thus, mites preferred leaves found in the lower parts of the tree canopy and avoided exposed leaves. This study provides a better understanding of the distribution of domatia bearing plants in South Africa and their associated mites and contributes to our knowledge of the biodiversity of mites in the region. Furthermore, this study also adds to our understanding of the leaf domatia - mite mutualism in Africa. The applied example looking at the plant-mite mutualism in Coffea arabica highlights the importance of this mutualism in commercial plants.
- Full Text:
- Date Issued: 2018
- Authors: Situngu, Sivuyisiwe
- Date: 2018
- Subjects: Insect-plant relationships , Mites , Mutualism (Biology) , Biological pest control agents
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63334 , vital:28394
- Description: Plants have various traits which allow them to cope and resist their enemies including both insects and fungi . In some cases such traits allow plants to build mutualistic relationships with natural enemies of plant pests. This is the case in many dicotyledonous plants which produce leaf domatia. Leaf domatia are plant cavities usually found in the axils of major veins in the abaxial side of leaves. They are usually associated with mites and often mediate mutualistic relationships with predacious mites. Mites use leaf domatia primarily for shelter, to reproduce, and to develop. In turn, plants benefit from having predaceous mites on their leaves, because mites act as plant “bodyguards” and offer defence against pathogens and small arthropod herbivores. This phenomenon has been well documented all over the world, but Africa remains disproportionally understudied. The aim of this study was to fill the gap that exists in our knowledge of the extent of the distribution of leaf domatia-mite mutualisms and generate a better understanding of the diversity of mites found within leaf domatia from an African perspective. This was done by surveying plant species that bear leaf domatia from different vegetation types in South Africa. The plants with leaf domatia were examined for the presence of mites in order to determine patterns of mite abundance and diversity and, in so doing, address the following questions: • Does each tree species host have a specific mite or mite assemblage? • Do some mites prefer certain types of leaf domatia? • Do mites prefer a specific place in the tree canopy and does the microclimate in the tree canopy affect the distribution of mites? • Do different vegetation sites and types differ in their mite diversity and species composition? • Does mite abundance and diversity vary with seasons? Do coffee plantations have a different suite of mites than the adjacent forest? The anatomical structures of leaf domatia from six selected plant species(Coffea arabica, Gardenia thunbergia, Rothmannia capensis, Rothmannia globosa (Rubiaceae), Ocotea bullata (Lauraceae) and Tecoma capensis (Bignoniaceae) with different types of leaf domatia were also studied. The results from this study suggested that the key futures which distinguish domatia are the presence of an extra layer of tissue in the lower epidermis, a thick cuticle, cuticular folds, the presence of trichomes and an invagination. This study provides a better understating of the structure of leaf domatia. Leaf domatia bearing plants are widely distributed in South Africa, and species and vegetation-specific associations were assessed. Over 250 plant specimens with leaf domatia were collected and examined and more than 60 different mite species were found in association with the sampled plant species. The majority of mites found within the domatia of these tree species were predaceous and included mites from Stigmatidae, Tydeidae and Phytoseiidae. Furthermore, 15 new species were collected, suggesting that mites are understudied in South Africa. This study showed that the different vegetation types sampled did not differ markedly in terms of their mite biota and that similar mites were found across the region, and the association between leaf domatia and mites was found to be opportunistic and that mites had no preference for any particular domatia types. No host specificity relationship was observed between plants and mites. The assessment of mites associated with Coffea arabica showed that indigenous mites are able to colonise and establish a beneficial mutualism on exotic species. This is important as it ascertains that economically important plants that are cultivated outside their area of natural distribution can still benefit from this mutualism. This study also found that mite abundance and diversity in plants with leaf domatia were influenced by factors such as temperature, relative humidity and rainfall. Mite communities found in association with domatia changed as the year progressed and over the seasons. The seasonal fluctuations varied between the sampled plant species. In addition, this study found that mites were sensitive to extreme environmental conditions, and thus, mites preferred leaves found in the lower parts of the tree canopy and avoided exposed leaves. This study provides a better understanding of the distribution of domatia bearing plants in South Africa and their associated mites and contributes to our knowledge of the biodiversity of mites in the region. Furthermore, this study also adds to our understanding of the leaf domatia - mite mutualism in Africa. The applied example looking at the plant-mite mutualism in Coffea arabica highlights the importance of this mutualism in commercial plants.
- Full Text:
- Date Issued: 2018
A multi-threading software countermeasure to mitigate side channel analysis in the time domain
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
- Full Text:
- Date Issued: 2019
Responding to iconic images of risk through reflexive and narrative enquiry represented in a stratified text for environmental education readers
- Authors: Murphy, Mary
- Date: 2019
- Subjects: Sustainability -- Study and teaching , Environmental education -- Philosophy , Environmental degradation -- Study and teaching , Environmental degradation -- Philosophy , Reflection (Philosophy) , Archer, Margaret S (Margaret Scotford). Structure, agency, and the internal conversation
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/96768 , vital:31318
- Description: This thesis presents a stratified textual strategy to represent meaning developed through reflexive and narrative enquiry of environmental risk. Meaning that emerged in responses to iconic images of risk. Umberto Eco cautioned that iconic images over time become conventional taking over from that which they represent. Representations of risk become embedded through cultural coding. Semiotic theory provided access to the contextual and cultural content of environmental education as experienced during professional work as a radio presenter of “Environmental Matters”, as an environmental educator and activist. Methodological rigour was applied through the application of Margaret Archer's theory of the internal conversation and use of an online content management system. Both the reflexive tool of the internal conversation and the textual mechanism of the blog encouraged commitment to Paul Hart's criteria of trustworthiness and authenticity in the process of building the semiotic structure of the PhD. The Internal Conversation was used as a mediating tool in the PhD process and is presented in practice. Rethinking environmental risk from other species' perspectives through imagined experience was achieved through narrative enquiry. A noted anthropocentric limitation of the inability to interview animals for their experience of human-imposed risk was mitigated through representing the imagined, possible perspectives through story, which invites the reader to join the meaning-making process and open up discussions for and about environmental issues and action. This noted anthropocentrism was evident in debates among the characters about violence and non-violence as a conditioned theme and topic discussed in previous academic research about terrorism in divided societies. The story illustrates how the main character, a penguin called Polo, navigates through emerging meaning within a structure that confronts him with choices that end with a decision to become an agent for change. This story is a narrative example of the morphogenetic process. The multi-textual strategy presents possible methods for the exploration of risk (Vol. 1), reflexivity (Vol. 2) and representation (Vol. 3) for the application and contribution in/to environmental education.
- Full Text:
- Date Issued: 2019
- Authors: Murphy, Mary
- Date: 2019
- Subjects: Sustainability -- Study and teaching , Environmental education -- Philosophy , Environmental degradation -- Study and teaching , Environmental degradation -- Philosophy , Reflection (Philosophy) , Archer, Margaret S (Margaret Scotford). Structure, agency, and the internal conversation
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/96768 , vital:31318
- Description: This thesis presents a stratified textual strategy to represent meaning developed through reflexive and narrative enquiry of environmental risk. Meaning that emerged in responses to iconic images of risk. Umberto Eco cautioned that iconic images over time become conventional taking over from that which they represent. Representations of risk become embedded through cultural coding. Semiotic theory provided access to the contextual and cultural content of environmental education as experienced during professional work as a radio presenter of “Environmental Matters”, as an environmental educator and activist. Methodological rigour was applied through the application of Margaret Archer's theory of the internal conversation and use of an online content management system. Both the reflexive tool of the internal conversation and the textual mechanism of the blog encouraged commitment to Paul Hart's criteria of trustworthiness and authenticity in the process of building the semiotic structure of the PhD. The Internal Conversation was used as a mediating tool in the PhD process and is presented in practice. Rethinking environmental risk from other species' perspectives through imagined experience was achieved through narrative enquiry. A noted anthropocentric limitation of the inability to interview animals for their experience of human-imposed risk was mitigated through representing the imagined, possible perspectives through story, which invites the reader to join the meaning-making process and open up discussions for and about environmental issues and action. This noted anthropocentrism was evident in debates among the characters about violence and non-violence as a conditioned theme and topic discussed in previous academic research about terrorism in divided societies. The story illustrates how the main character, a penguin called Polo, navigates through emerging meaning within a structure that confronts him with choices that end with a decision to become an agent for change. This story is a narrative example of the morphogenetic process. The multi-textual strategy presents possible methods for the exploration of risk (Vol. 1), reflexivity (Vol. 2) and representation (Vol. 3) for the application and contribution in/to environmental education.
- Full Text:
- Date Issued: 2019
The investigation of type-specific features of the copper coordinating AA9 proteins and their effect on the interaction with crystalline cellulose using molecular dynamics studies
- Authors: Moses, Vuyani
- Date: 2018
- Subjects: Copper proteins , Cellulose , Molecular dynamics , Cellulose -- Biodegradation , Bioinformatics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58327 , vital:27230
- Description: AA9 proteins are metallo-enzymes which are crucial for the early stages of cellulose degradation. AA9 proteins have been suggested to cleave glycosidic bonds linking cellulose through the use of their Cu2+ coordinating active site. AA9 proteins possess different regioselectivities depending on the resulting cleavage they form and as result, are grouped accordingly. Type 1 AA9 proteins cleave the C1 carbon of cellulose while Type 2 AA9 proteins cleave the C4 carbon and Type 3 AA9 proteins cleave either C1 or C4 carbons. The steric congestion of the AA9 active site has been proposed to be a contributor to the observed regioselectivity. As such, a bioinformatics characterisation of type-specific sequence and structural features was performed. Initially AA9 protein sequences were obtained from the Pfam database and multiple sequence alignment was performed. The sequences were phylogenetically characterised and sequences were grouped into their respective types and sub-groups were identified. A selection analysis was performed on AA9 LPMO types to determine the selective pressure acting on AA9 protein residues. Motif discovery was then performed to identify conserved sequence motifs in AA9 proteins. Once type-specific sequence features were identified structural mapping was performed to assess possible effects on substrate interaction. Physicochemical property analysis was also performed to assess biochemical differences between AA9 LPMO types. Molecular dynamics (MD) simulations were then employed to dynamically assess the consequences of the discovered type-specific features on AA9-cellulose interaction. Due to the absence of AA9 specific force field parameters MD simulations were not readily applicable. As a result, Potential Energy Surface (PES) scans were performed to evaluate the force field parameters for the AA9 active site using the PM6 semi empirical approach and least squares fitting. A Type 1 AA9 active site was constructed from the crystal structure 4B5Q, encompassing only the Cu2+ coordinating residues, the Cu2+ ion and two water residues. Due to the similarity in AA9 active sites, the Type force field parameters were validated on all three AA9 LPMO types. Two MD simulations for each AA9 LPMO types were conducted using two separate Lennard-Jones parameter sets. Once completed, the MD trajectories were analysed for various features including the RMSD, RMSF, radius of gyration, coordination during simulation, hydrogen bonding, secondary structure conservation and overall protein movement. Force field parameters were successfully evaluated and validated for AA9 proteins. MD simulations of AA9 proteins were able to reveal the presence of unique type-specific binding modes of AA9 active sites to cellulose. These binding modes were characterised by the presence of unique type-specific loops which were present in Type 2 and 3 AA9 proteins but not in Type 1 AA9 proteins. The loops were found to result in steric congestion that affects how the Cu2+ ion interacts with cellulose. As a result, Cu2+ binding to cellulose was observed for Type 1 and not Type 2 and 3 AA9 proteins. In this study force field parameters have been evaluated for the Type 1 active site of AA9 proteins and this parameters were evaluated on all three types and binding. Future work will focus on identifying the nature of the reactive oxygen species and performing QM/MM calculations to elucidate the reactive mechanism of all three AA9 LPMO types.
- Full Text:
- Date Issued: 2018
- Authors: Moses, Vuyani
- Date: 2018
- Subjects: Copper proteins , Cellulose , Molecular dynamics , Cellulose -- Biodegradation , Bioinformatics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/58327 , vital:27230
- Description: AA9 proteins are metallo-enzymes which are crucial for the early stages of cellulose degradation. AA9 proteins have been suggested to cleave glycosidic bonds linking cellulose through the use of their Cu2+ coordinating active site. AA9 proteins possess different regioselectivities depending on the resulting cleavage they form and as result, are grouped accordingly. Type 1 AA9 proteins cleave the C1 carbon of cellulose while Type 2 AA9 proteins cleave the C4 carbon and Type 3 AA9 proteins cleave either C1 or C4 carbons. The steric congestion of the AA9 active site has been proposed to be a contributor to the observed regioselectivity. As such, a bioinformatics characterisation of type-specific sequence and structural features was performed. Initially AA9 protein sequences were obtained from the Pfam database and multiple sequence alignment was performed. The sequences were phylogenetically characterised and sequences were grouped into their respective types and sub-groups were identified. A selection analysis was performed on AA9 LPMO types to determine the selective pressure acting on AA9 protein residues. Motif discovery was then performed to identify conserved sequence motifs in AA9 proteins. Once type-specific sequence features were identified structural mapping was performed to assess possible effects on substrate interaction. Physicochemical property analysis was also performed to assess biochemical differences between AA9 LPMO types. Molecular dynamics (MD) simulations were then employed to dynamically assess the consequences of the discovered type-specific features on AA9-cellulose interaction. Due to the absence of AA9 specific force field parameters MD simulations were not readily applicable. As a result, Potential Energy Surface (PES) scans were performed to evaluate the force field parameters for the AA9 active site using the PM6 semi empirical approach and least squares fitting. A Type 1 AA9 active site was constructed from the crystal structure 4B5Q, encompassing only the Cu2+ coordinating residues, the Cu2+ ion and two water residues. Due to the similarity in AA9 active sites, the Type force field parameters were validated on all three AA9 LPMO types. Two MD simulations for each AA9 LPMO types were conducted using two separate Lennard-Jones parameter sets. Once completed, the MD trajectories were analysed for various features including the RMSD, RMSF, radius of gyration, coordination during simulation, hydrogen bonding, secondary structure conservation and overall protein movement. Force field parameters were successfully evaluated and validated for AA9 proteins. MD simulations of AA9 proteins were able to reveal the presence of unique type-specific binding modes of AA9 active sites to cellulose. These binding modes were characterised by the presence of unique type-specific loops which were present in Type 2 and 3 AA9 proteins but not in Type 1 AA9 proteins. The loops were found to result in steric congestion that affects how the Cu2+ ion interacts with cellulose. As a result, Cu2+ binding to cellulose was observed for Type 1 and not Type 2 and 3 AA9 proteins. In this study force field parameters have been evaluated for the Type 1 active site of AA9 proteins and this parameters were evaluated on all three types and binding. Future work will focus on identifying the nature of the reactive oxygen species and performing QM/MM calculations to elucidate the reactive mechanism of all three AA9 LPMO types.
- Full Text:
- Date Issued: 2018
A critique of language policy and implementation strategies used in selected institutions of higher learning in South Africa
- Authors: Somlata, Zakhile
- Date: 2018
- Subjects: Language policy South Africa , Translanguaging (Linguistics) , Language and education South Africa , Language and languages Study and teaching South Africa , Education, Higher South Africa , Multilingualism South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62571 , vital:28208
- Description: This thesis evaluated the language policy implementation strategies used in selected universities of South Africa. The Constitution of the Republic of South African (1996) recognises eleven official languages, namely: English, Afrikaans, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, SiSwati, Sepedi, Tshivenda and Xitsonga. These official languages should enjoy the parity of esteem in all domains. The language practices are very important in the education of students at all levels of education but this study focuses on the language policy implementation in universities. Most universities of South Africa have their language policies but the dilemma is on the implementation of those language policies. The overarching aim of this study is to evaluate how university use language policy for access and success of the students and to assess the language policy implementation strategies, monitoring and evaluation. The language is central to the success of the students and this study further investigated to what extent are the universities use the linguistic repertoires of the students in their education. This study is rooted in orientations of language planning: Language as problem, language as right and language as resource (Ruiz, 1984). This thesis employed a mixed methods approach (qualitative and quantitative method) with convergent parallel design. The data was collected from eleven universities of South Africa and the participants in each university were the "Key informants" (experts and insiders) which comprised of member of Executive Management, a member of the Institutional Language Committee and a language lecturer; and a cohort of forty third year students. The Key informants participated in the qualitative data collection through the structured interviews. The forty third year students participated in the quantitative data collected through survey questionnaires. The language policy documents of the universities were also sampled to get a better understanding of the real language practices and the language policy. The thematic analysis was used to analyse transcripts that were developed from the interviews, data from the students was analysed through descriptive and inferential analyses with Statistical Package for the Social Sciences (SPSS) as a statistical test and document analysis was used to analyse the language policies; The findings show that universities have commitment to access of the students to institutions of Higher Education. The success of the students is being thwarted by the monolingual approach where most of the universities use English only as the medium of instruction. The monolingual approach negatively affects the academic success and excellent academic performance of the majority of students. The findings show that there is high demand from the students that the course materials should be provided in African languages. All selected universities have their language policy which is something positive but most of them are outdated because they need to be reviewed at least after five years. The findings demonstrate that most universities lack the language policy implementation plans. The nonexistence of the language policy implementation plan adversely affects the implementation of the language policy. The study recommends that universities should provide the learning resources in African languages to meet the demands of the students. To maximise the success, students should be examined in any official languages of the university. The language policy implementation plans should be developed urgently so as to improve language policy implementation in universities. , Le thesisi iphonononge iindlela zokusetyenziswa komgaqo-nkqubo wolwimi kwiiyunivesithi ezichongiweyo zaseMzantsi Afrika. Umgaqo-siseko waseMzantsi Afrika (1996) athathela ingqalelo iilwimi ezisemthethweni ezilishumi elinanye, isiNgesi, isiBhulu, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, Sepedi, SiSwati, Tshivenda neXitsonga. Ezi lwimi zisemthethweni zifanele ukuba zisetyenziswe ngokulinganayo kuzo zonke iinkalo. Ukusetyenziswa kweelwimi kubalulekile kakhulu kwimfundo yabantwana kuwo onke amanqanaba emfundo kodwa olu phando lugxile ekusetyenzisweni komgaqo-nkqubo wolwimi kwiiyunivesithi. Uninzi lweeyunivesithi zinayo imigaqo-nkqubo yolwimi kodwa ingxaki isekusetyenzisweni kwaloo migaqo-nkqubo yolwimi. Ezona njongo zolu phando kukuphonononga ukuba iiyunivesithi ziyisebenzisa njani na imigaqo-nkqubo yolwimi ukuze abafundi bafikelele kwaye baphumelele ezifundweni kwakhona nokugocagoca izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi nokuhlola ukusebenza kwezo zicwangciso. Ulwimi ngundoqo kwimpumelelo yabafundi kwaye umyinge wokusetyenziswa kweelwimi zabafundi ekufundeni kwabo kuthe kwaphandwa. Esi sifundo sisekelwe kwiindlela zocwangciso-lwimi: Ulwimi njengengxaki, ulwimi njengelungelo nolwimi njengesixhobo (Ruiz, 1984). Le thesisi esebenzise indlela yophando entlantlu-mbini (eyobunjani neyobungakanani) kunye noyilo lwendibaniso kokunxuseneyo. Idatha yathi yaqokelelwa kwiiyunivesithi ezilishumi elinanye eMzantsi Afrika kwaye abathabathi nxaxheba babandakanya ilungu lesigqeba solawulo, ilungu lekomiti yeelwimi eyunivesithi nomhlohli wolwimi; kunye nabafundi abakunyaka wesithathu kwizifundo zabo kwiyunivesithi nganye. Idatha yaqokelelwa kubadlulisi-lwazi abaphambili beeyunivesithi ngodliwano-ndlebe oluqingqiweyo. Abafundi abalishumi elinesine bathi bathabathi inxaxheba kuqokelelo lwedatha ngokuthi bagcwalise uludwe lwemibuzo eyayicwangcisiwe. Umaxwebhu omgaqo-nkqubo wolwimi athi achongwa ukuze kubekho ukuqondakala phakathi kokusetyenziswa kolwimi kunye nokumgaqo-nkqubo wolwimi. Uhlalutyo ngokomxholo lwathi lwasetyenziswa ukuhlalutya ulwazi olwabhalwayo luvela kudliwano-ndlebe olwashicilelwayo, idatha eyayisuka kubafundi yathi yahlalutywa ngokusebenzisa uhlalutyo ngokwenkcazelo nangokuthelekelela kunye neStatistical Pakage for Social Sciences (SPSS) njengesixhobo senkcukacha-manani kwaye uhlalutyo loxwebhu lwathi lwasetyenziswa ukuhlalutya imigaqo-nkqubo yolwimi. Iziphumo zibonakalisa ukuba iiyunivesithi zizibophelele ekufikelelekeni kwabafundi kumaziko emfundo ephakamileyo. Impumelelo yabafundi ithi ithityazwe kukusetyenziswa kolwimi olunye apho uninzi lweeyunivesithi zisebenzisa isiNgesi kuphela njengolwimi lokufunda nokufundisa. Ukusetyenziswa kolwimi olunye kuthi kuchaphazela gwenxa impumelelo yabafundi nokuqhuba ngcono ezifundweni. Iziphumo zibonakalisa ukuba kukho imfuno emmandla kubafundi yokuba izixhobo zokufunda nokufundisa zifumaneke nangeelwimi zesiNtu. Inyathelo elihle lelokuba zonke iiyunivesithi ezichongiweyo zinayo imigaqo-nkqubo yolwimi kodwa imigaqo-nkqubo yolwimi emininzi midala kuba ifanelwe ukuba iphononongwe emva kweminyaka emihlanu ubuncinane. Iziphumo zibonakalisa ukuba iiyunivesithi azinazo izicwangciso zokusetyenziswa kwemigaqo-nkqubo yolwimi. Ukungabikho kwesicwangciso sokusetyenziswa komgaqo-nkqubo wolwimi kuchaphazela gwenxa ukusetyenziswa kwawo. Olu phando lundulula ukuba iiyunivesithi zifanele ukuba zibonelele ngezixhobo zokufunda nokufundisa ezingeelwimi zesiNtu ukukhawulelana neemfuno zabafundi. Ukwandisa impumelelo, abafundi kufanele ukuba bavavanywe ngalo naluphi na ulwimi olusemthethweni lweyunivesithi. Izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi zifanele ukuba ziveliswe njengenyewe engxamisekileyo ukuze kuphuculwe ukusetyenziswa kwemigaqo- nkqubo yolwimi kwiiyunivesithi.
- Full Text:
- Date Issued: 2018
- Authors: Somlata, Zakhile
- Date: 2018
- Subjects: Language policy South Africa , Translanguaging (Linguistics) , Language and education South Africa , Language and languages Study and teaching South Africa , Education, Higher South Africa , Multilingualism South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62571 , vital:28208
- Description: This thesis evaluated the language policy implementation strategies used in selected universities of South Africa. The Constitution of the Republic of South African (1996) recognises eleven official languages, namely: English, Afrikaans, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, SiSwati, Sepedi, Tshivenda and Xitsonga. These official languages should enjoy the parity of esteem in all domains. The language practices are very important in the education of students at all levels of education but this study focuses on the language policy implementation in universities. Most universities of South Africa have their language policies but the dilemma is on the implementation of those language policies. The overarching aim of this study is to evaluate how university use language policy for access and success of the students and to assess the language policy implementation strategies, monitoring and evaluation. The language is central to the success of the students and this study further investigated to what extent are the universities use the linguistic repertoires of the students in their education. This study is rooted in orientations of language planning: Language as problem, language as right and language as resource (Ruiz, 1984). This thesis employed a mixed methods approach (qualitative and quantitative method) with convergent parallel design. The data was collected from eleven universities of South Africa and the participants in each university were the "Key informants" (experts and insiders) which comprised of member of Executive Management, a member of the Institutional Language Committee and a language lecturer; and a cohort of forty third year students. The Key informants participated in the qualitative data collection through the structured interviews. The forty third year students participated in the quantitative data collected through survey questionnaires. The language policy documents of the universities were also sampled to get a better understanding of the real language practices and the language policy. The thematic analysis was used to analyse transcripts that were developed from the interviews, data from the students was analysed through descriptive and inferential analyses with Statistical Package for the Social Sciences (SPSS) as a statistical test and document analysis was used to analyse the language policies; The findings show that universities have commitment to access of the students to institutions of Higher Education. The success of the students is being thwarted by the monolingual approach where most of the universities use English only as the medium of instruction. The monolingual approach negatively affects the academic success and excellent academic performance of the majority of students. The findings show that there is high demand from the students that the course materials should be provided in African languages. All selected universities have their language policy which is something positive but most of them are outdated because they need to be reviewed at least after five years. The findings demonstrate that most universities lack the language policy implementation plans. The nonexistence of the language policy implementation plan adversely affects the implementation of the language policy. The study recommends that universities should provide the learning resources in African languages to meet the demands of the students. To maximise the success, students should be examined in any official languages of the university. The language policy implementation plans should be developed urgently so as to improve language policy implementation in universities. , Le thesisi iphonononge iindlela zokusetyenziswa komgaqo-nkqubo wolwimi kwiiyunivesithi ezichongiweyo zaseMzantsi Afrika. Umgaqo-siseko waseMzantsi Afrika (1996) athathela ingqalelo iilwimi ezisemthethweni ezilishumi elinanye, isiNgesi, isiBhulu, isiNdebele, isiXhosa, isiZulu, Sesotho, Setswana, Sepedi, SiSwati, Tshivenda neXitsonga. Ezi lwimi zisemthethweni zifanele ukuba zisetyenziswe ngokulinganayo kuzo zonke iinkalo. Ukusetyenziswa kweelwimi kubalulekile kakhulu kwimfundo yabantwana kuwo onke amanqanaba emfundo kodwa olu phando lugxile ekusetyenzisweni komgaqo-nkqubo wolwimi kwiiyunivesithi. Uninzi lweeyunivesithi zinayo imigaqo-nkqubo yolwimi kodwa ingxaki isekusetyenzisweni kwaloo migaqo-nkqubo yolwimi. Ezona njongo zolu phando kukuphonononga ukuba iiyunivesithi ziyisebenzisa njani na imigaqo-nkqubo yolwimi ukuze abafundi bafikelele kwaye baphumelele ezifundweni kwakhona nokugocagoca izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi nokuhlola ukusebenza kwezo zicwangciso. Ulwimi ngundoqo kwimpumelelo yabafundi kwaye umyinge wokusetyenziswa kweelwimi zabafundi ekufundeni kwabo kuthe kwaphandwa. Esi sifundo sisekelwe kwiindlela zocwangciso-lwimi: Ulwimi njengengxaki, ulwimi njengelungelo nolwimi njengesixhobo (Ruiz, 1984). Le thesisi esebenzise indlela yophando entlantlu-mbini (eyobunjani neyobungakanani) kunye noyilo lwendibaniso kokunxuseneyo. Idatha yathi yaqokelelwa kwiiyunivesithi ezilishumi elinanye eMzantsi Afrika kwaye abathabathi nxaxheba babandakanya ilungu lesigqeba solawulo, ilungu lekomiti yeelwimi eyunivesithi nomhlohli wolwimi; kunye nabafundi abakunyaka wesithathu kwizifundo zabo kwiyunivesithi nganye. Idatha yaqokelelwa kubadlulisi-lwazi abaphambili beeyunivesithi ngodliwano-ndlebe oluqingqiweyo. Abafundi abalishumi elinesine bathi bathabathi inxaxheba kuqokelelo lwedatha ngokuthi bagcwalise uludwe lwemibuzo eyayicwangcisiwe. Umaxwebhu omgaqo-nkqubo wolwimi athi achongwa ukuze kubekho ukuqondakala phakathi kokusetyenziswa kolwimi kunye nokumgaqo-nkqubo wolwimi. Uhlalutyo ngokomxholo lwathi lwasetyenziswa ukuhlalutya ulwazi olwabhalwayo luvela kudliwano-ndlebe olwashicilelwayo, idatha eyayisuka kubafundi yathi yahlalutywa ngokusebenzisa uhlalutyo ngokwenkcazelo nangokuthelekelela kunye neStatistical Pakage for Social Sciences (SPSS) njengesixhobo senkcukacha-manani kwaye uhlalutyo loxwebhu lwathi lwasetyenziswa ukuhlalutya imigaqo-nkqubo yolwimi. Iziphumo zibonakalisa ukuba iiyunivesithi zizibophelele ekufikelelekeni kwabafundi kumaziko emfundo ephakamileyo. Impumelelo yabafundi ithi ithityazwe kukusetyenziswa kolwimi olunye apho uninzi lweeyunivesithi zisebenzisa isiNgesi kuphela njengolwimi lokufunda nokufundisa. Ukusetyenziswa kolwimi olunye kuthi kuchaphazela gwenxa impumelelo yabafundi nokuqhuba ngcono ezifundweni. Iziphumo zibonakalisa ukuba kukho imfuno emmandla kubafundi yokuba izixhobo zokufunda nokufundisa zifumaneke nangeelwimi zesiNtu. Inyathelo elihle lelokuba zonke iiyunivesithi ezichongiweyo zinayo imigaqo-nkqubo yolwimi kodwa imigaqo-nkqubo yolwimi emininzi midala kuba ifanelwe ukuba iphononongwe emva kweminyaka emihlanu ubuncinane. Iziphumo zibonakalisa ukuba iiyunivesithi azinazo izicwangciso zokusetyenziswa kwemigaqo-nkqubo yolwimi. Ukungabikho kwesicwangciso sokusetyenziswa komgaqo-nkqubo wolwimi kuchaphazela gwenxa ukusetyenziswa kwawo. Olu phando lundulula ukuba iiyunivesithi zifanele ukuba zibonelele ngezixhobo zokufunda nokufundisa ezingeelwimi zesiNtu ukukhawulelana neemfuno zabafundi. Ukwandisa impumelelo, abafundi kufanele ukuba bavavanywe ngalo naluphi na ulwimi olusemthethweni lweyunivesithi. Izicwangciso zokusetyenziswa komgaqo-nkqubo wolwimi zifanele ukuba ziveliswe njengenyewe engxamisekileyo ukuze kuphuculwe ukusetyenziswa kwemigaqo- nkqubo yolwimi kwiiyunivesithi.
- Full Text:
- Date Issued: 2018
Biochemical characterisation and small molecule modulation of the interaction between two cytosolic Hsp70s from Trypanosoma brucei and potential co-chaperones
- Authors: Bentley, Stephen John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63402 , vital:28407
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
- Authors: Bentley, Stephen John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63402 , vital:28407
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
Constraining simulation uncertainties in a hydrological model of the Congo River Basin including a combined modelling approach for channel-wetland exchanges
- Authors: Kabuya, Pierre Mulamba
- Date: 2021-04
- Subjects: Congo River Watershed , Watersheds -- Congo (Democratic Republic) , Hydrologic models , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Wetland hydrology
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177997 , vital:42897 , 10.21504/10962/177997
- Description: Compared to other large river basins of the world, such as the Amazon, the Congo River Basin appears to be the most ungauged and less studied. This is partly because the basin lacks sufficient observational hydro-climatic monitoring stations and appropriate information on physiographic basin properties at a spatial scale deemed for hydrological applications, making it difficult to estimate water resources at the scale of sub-basins (Chapter 3). In the same time, the basin is facing the challenges related to rapid population growth, uncontrolled urbanisation as well as climate change. Adequate quantification of hydrological processes across different spatial and temporal scales in the basin, and the drivers of change, is essential for prediction and strategic planning to ensure sustainable management of water resources in the Congo River Basin. Hydrological models are particularly important to generate the required information. However, the shortness of the available streamflow records, lack of spatial representativeness of the available streamflow gauging stations and the lack of understanding of the processes in channel-wetland exchanges, are the main challenges that constrain the use of traditional approaches to models development. They also contribute to increased uncertainty in the estimation of water resources across the basin (Chapter 1 and 2). Given this ungauged nature of the Congo River Basin, it is important to resort to hydrological modelling approaches that can reasonably quantify and model the uncertainty associated with water resources estimation (Chapter 4) to make hydrological predictions reliable. This study explores appropriate methods for hydrological predictions and water resources assessment in ungauged catchments of the Congo River Basin. In this context, the core modelling framework combines the quantification of uncertainty in constraint indices, hydrological modelling and hydrodynamic modelling. The latter accounts for channel-wetland exchanges in sub-basins where wetlands exert considerable influence on downstream flow regimes at the monthly time scale. The constraint indices are the characteristics of a sub-basin’s long-term hydrological behaviour and may reflect the dynamics of the different components of the catchment water balance such as climate, water storage and different runoff processes. Currently, six constraint indices namely the mean monthly runoff volume (MMQ in m3 *106), mean monthly groundwater recharge depth (MMR in mm), the 10th, 50th and 90th percentiles of the flow duration curve expressed as a fraction of MMQ (Q10/MMQ, Q50/MMQ, Q90/MMQ) and the percentage of time that zero flows are expected (%Zero), are used in the modelling approach. These were judged to be the minimum number of key indices that can discriminate between different hydrological responses. The constraint indices in the framework help to determine an uncertainty range within which behavioural model parameters of the expected hydrological response can be identified. Predictive equations of the constraint indices across all climate and physiographic regions of the Congo Basin were based only on the aridity index because it was the most influential sub-basin attribute (Chapter 5) for which quantitative information was available. The degree of uncertainty in the constraint Q10/MMQ and Q50/MMQ indices is less than 41%, while it is somewhat higher for the mean monthly runoff (MMQ) and Q90/MMQ constraint indices. The established uncertainty ranges of the constraint indices were tested in some selected sub-basins of the Congo Basin, including the Lualaba (93 sub-basins), Sangha (24 sub-basins), Oubangui (19 sub-basins), Batéké plateaux (4 sub-basins), Kasai (4 sub-basins) and Inkisi (3 sub-basins). The results proved useful through the application of a 2-stage uncertainty approach of the PITMAN model. However, it comes out of this study that the application of the original constraint indices ranges (Chapter 5) generated satisfactory simulation results in some areas, while in others both small and large adjustments were required to fully capture some aspects of the observed hydrological responses (Chapter 6). Part of the reason is attributed to the availability and quality of streamflow data used to develop the constraint indices ranges (Chapter 5). The main issue identified in the modelling process was whether the changes made to the original constraints at headwater-gauged sub-basins can be applied to ungauged upstream sub-basins to match the observed flow at downstream gauging stations. Ideally, only gauged sub-basin’s constraints can be easily revised based on the observed flow. However, the refinement made to gauged sub-basins alone may fail to substantially affect the results if ungauged upstream sub-basins exert a major impact on defining downstream hydrological response. The majority of gauging stations used in this analysis are located downstream of many upstream ungauged sub-basins and therefore adjustments were required in ungauged sub-basins. These adjustments consist of shifting the full range of a constraint index either towards higher or lower values, depending on the degree to which the simulated uncertainty bounds depart from the observed flow. While this modelling approach seems effective in capturing many aspects of the hydrological responses with a reduced level of uncertainty compared to a previous study, it is recommended that the approach be extended to the remaining parts of the Congo Basin and assessed under current and future development conditions including environmental changes. A 2D hydrodynamic river-wetland model (LISFLOOD-FP) has been used to explicitly represent the inundation process exchanges between river channels and wetland systems. The hydrodynamic modelling outputs are used to calibrate the PITMAN wetland sub-model parameters. The five hydrodynamic models constructed for Ankoro, Kamalondo, Kundelungu, Mweru and Tshiangalele wetland systems have been partially validated using independent estimates of inundation extents available from Landsat imagery. Other sources of data such as remote sensing of water level altimetry, SAR images and wetland storage estimates may be used to improve the validation results. However, the important objective in this study was to make sure that flow volume exchanges between river channels and their adjacent floodplains were being simulated realistically. The wetland sub-model parameters are calibrated in a spreadsheet version of the PITMAN wetland routine to achieve visual correspondence between the LISFLOOD-FP and PITMAN wetland sub-model outputs (Storage volumes and channel outputs). The hysteretic patterns of the river-wetland processes were quantified using hysteresis indices and were associated with the spill and return flow parameters of the wetland sub-model and eventually with the wetland morphometric characteristics. One example is the scale parameter of the return flow function (AA), which shows a good relationship with the average surface slope of the wetland when the coefficient parameter (BB) of the same function is kept constant to a value of 1.25. The same parameter (AA) is a good indicator of the wetland emptying mechanism. A small AA indicates a wetland that slowly releases its flow, resulting in a highly delayed and attenuated hydrological response in downstream sub-basins. This understanding has a practical advantage for the estimation of the PITMAN wetland parameters in the many areas where it is not possible, or where the resources are not available, to run complex hydrodynamic models (Chapter 7). The inclusion of these LISFLOOD-FP informed wetland parameters in the basin-scale hydrological modelling results in acceptable simulations for the lower Lualaba drainage system. The small wetlands, like Ankoro and Tshiangalele, have a negligible impact on downstream flow regimes, whereas large wetlands, such as Kamalondo and Mweru, have very large impacts. In general, the testing of the original constraint indices in the region of wetlands and further downstream of the Lualaba drainage system has shown acceptable results. However, there remains an unresolved uncertainty issue related to the under and over-estimation of some aspects of the hydrological response at both Mulongo and Ankoro, two gauging stations in the immediate downstream of the Kamalondo wetland system. It is difficult to attribute this uncertainty to Kamalondo wetland parameters alone because many of the incremental sub-basins contributing to wetland inflows are ungauged. The issue at Mulongo is the under simulation of low flow, while the high flows at the Ankoro gauging station are over-simulated. However, the pattern of the calibrated constraint indices in this region (Chapter 8) shows that the under simulation of low flow at Mulongo cannot be attributed to incremental sub-basins (between Bukama, Kapolowe and Mulongo gauging stations), because their Q90/MMQ constraint indices are even slightly above the original constraint ranges, but maintain a spatial consistency with sub-basins of other regions. Similarly, sub-basins located between Mulongo, Luvua and Ankoro gauging stations have high flow indices slightly below the original constraint ranges and therefore they are unlikely to be responsible for the over simulation of high flow at the Ankoro gauging station. These facts highlight the need for a further understanding of the complex wetland system of Kamalondo. Short-term data collection and monitoring programme are required. Important tributaries that drain to this wetland need to be monitored by installing water level loggers and periodically collecting flow data and river bathymetry. This programme should lead to the development of rating curves of wetland input tributaries. This would partially solve the unresolved uncertainty issues at the Ankoro and Mulongo gauging stations. The integrated modelling approach offers many opportunities in the Congo Basin. The quantified and modelled uncertainty helps to identify regions with high uncertainty and allows for the identification of various data collection and management strategies that can potentially contribute to the uncertainty reduction. The quantified channel-wetland exchanges contribute to the improvement of the overall knowledge of water resources estimation within the regions where the effects of wetlands are evident even at the monthly time scale. In contrast, ignoring uncertainty in the estimates of water resources availability means that water resources planning and management decisions in the Congo Basin will continue to be based on inadequate information and unquantified uncertainty, thus increasing the risk associated with water resources decision making. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Kabuya, Pierre Mulamba
- Date: 2021-04
- Subjects: Congo River Watershed , Watersheds -- Congo (Democratic Republic) , Hydrologic models , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Wetland hydrology
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177997 , vital:42897 , 10.21504/10962/177997
- Description: Compared to other large river basins of the world, such as the Amazon, the Congo River Basin appears to be the most ungauged and less studied. This is partly because the basin lacks sufficient observational hydro-climatic monitoring stations and appropriate information on physiographic basin properties at a spatial scale deemed for hydrological applications, making it difficult to estimate water resources at the scale of sub-basins (Chapter 3). In the same time, the basin is facing the challenges related to rapid population growth, uncontrolled urbanisation as well as climate change. Adequate quantification of hydrological processes across different spatial and temporal scales in the basin, and the drivers of change, is essential for prediction and strategic planning to ensure sustainable management of water resources in the Congo River Basin. Hydrological models are particularly important to generate the required information. However, the shortness of the available streamflow records, lack of spatial representativeness of the available streamflow gauging stations and the lack of understanding of the processes in channel-wetland exchanges, are the main challenges that constrain the use of traditional approaches to models development. They also contribute to increased uncertainty in the estimation of water resources across the basin (Chapter 1 and 2). Given this ungauged nature of the Congo River Basin, it is important to resort to hydrological modelling approaches that can reasonably quantify and model the uncertainty associated with water resources estimation (Chapter 4) to make hydrological predictions reliable. This study explores appropriate methods for hydrological predictions and water resources assessment in ungauged catchments of the Congo River Basin. In this context, the core modelling framework combines the quantification of uncertainty in constraint indices, hydrological modelling and hydrodynamic modelling. The latter accounts for channel-wetland exchanges in sub-basins where wetlands exert considerable influence on downstream flow regimes at the monthly time scale. The constraint indices are the characteristics of a sub-basin’s long-term hydrological behaviour and may reflect the dynamics of the different components of the catchment water balance such as climate, water storage and different runoff processes. Currently, six constraint indices namely the mean monthly runoff volume (MMQ in m3 *106), mean monthly groundwater recharge depth (MMR in mm), the 10th, 50th and 90th percentiles of the flow duration curve expressed as a fraction of MMQ (Q10/MMQ, Q50/MMQ, Q90/MMQ) and the percentage of time that zero flows are expected (%Zero), are used in the modelling approach. These were judged to be the minimum number of key indices that can discriminate between different hydrological responses. The constraint indices in the framework help to determine an uncertainty range within which behavioural model parameters of the expected hydrological response can be identified. Predictive equations of the constraint indices across all climate and physiographic regions of the Congo Basin were based only on the aridity index because it was the most influential sub-basin attribute (Chapter 5) for which quantitative information was available. The degree of uncertainty in the constraint Q10/MMQ and Q50/MMQ indices is less than 41%, while it is somewhat higher for the mean monthly runoff (MMQ) and Q90/MMQ constraint indices. The established uncertainty ranges of the constraint indices were tested in some selected sub-basins of the Congo Basin, including the Lualaba (93 sub-basins), Sangha (24 sub-basins), Oubangui (19 sub-basins), Batéké plateaux (4 sub-basins), Kasai (4 sub-basins) and Inkisi (3 sub-basins). The results proved useful through the application of a 2-stage uncertainty approach of the PITMAN model. However, it comes out of this study that the application of the original constraint indices ranges (Chapter 5) generated satisfactory simulation results in some areas, while in others both small and large adjustments were required to fully capture some aspects of the observed hydrological responses (Chapter 6). Part of the reason is attributed to the availability and quality of streamflow data used to develop the constraint indices ranges (Chapter 5). The main issue identified in the modelling process was whether the changes made to the original constraints at headwater-gauged sub-basins can be applied to ungauged upstream sub-basins to match the observed flow at downstream gauging stations. Ideally, only gauged sub-basin’s constraints can be easily revised based on the observed flow. However, the refinement made to gauged sub-basins alone may fail to substantially affect the results if ungauged upstream sub-basins exert a major impact on defining downstream hydrological response. The majority of gauging stations used in this analysis are located downstream of many upstream ungauged sub-basins and therefore adjustments were required in ungauged sub-basins. These adjustments consist of shifting the full range of a constraint index either towards higher or lower values, depending on the degree to which the simulated uncertainty bounds depart from the observed flow. While this modelling approach seems effective in capturing many aspects of the hydrological responses with a reduced level of uncertainty compared to a previous study, it is recommended that the approach be extended to the remaining parts of the Congo Basin and assessed under current and future development conditions including environmental changes. A 2D hydrodynamic river-wetland model (LISFLOOD-FP) has been used to explicitly represent the inundation process exchanges between river channels and wetland systems. The hydrodynamic modelling outputs are used to calibrate the PITMAN wetland sub-model parameters. The five hydrodynamic models constructed for Ankoro, Kamalondo, Kundelungu, Mweru and Tshiangalele wetland systems have been partially validated using independent estimates of inundation extents available from Landsat imagery. Other sources of data such as remote sensing of water level altimetry, SAR images and wetland storage estimates may be used to improve the validation results. However, the important objective in this study was to make sure that flow volume exchanges between river channels and their adjacent floodplains were being simulated realistically. The wetland sub-model parameters are calibrated in a spreadsheet version of the PITMAN wetland routine to achieve visual correspondence between the LISFLOOD-FP and PITMAN wetland sub-model outputs (Storage volumes and channel outputs). The hysteretic patterns of the river-wetland processes were quantified using hysteresis indices and were associated with the spill and return flow parameters of the wetland sub-model and eventually with the wetland morphometric characteristics. One example is the scale parameter of the return flow function (AA), which shows a good relationship with the average surface slope of the wetland when the coefficient parameter (BB) of the same function is kept constant to a value of 1.25. The same parameter (AA) is a good indicator of the wetland emptying mechanism. A small AA indicates a wetland that slowly releases its flow, resulting in a highly delayed and attenuated hydrological response in downstream sub-basins. This understanding has a practical advantage for the estimation of the PITMAN wetland parameters in the many areas where it is not possible, or where the resources are not available, to run complex hydrodynamic models (Chapter 7). The inclusion of these LISFLOOD-FP informed wetland parameters in the basin-scale hydrological modelling results in acceptable simulations for the lower Lualaba drainage system. The small wetlands, like Ankoro and Tshiangalele, have a negligible impact on downstream flow regimes, whereas large wetlands, such as Kamalondo and Mweru, have very large impacts. In general, the testing of the original constraint indices in the region of wetlands and further downstream of the Lualaba drainage system has shown acceptable results. However, there remains an unresolved uncertainty issue related to the under and over-estimation of some aspects of the hydrological response at both Mulongo and Ankoro, two gauging stations in the immediate downstream of the Kamalondo wetland system. It is difficult to attribute this uncertainty to Kamalondo wetland parameters alone because many of the incremental sub-basins contributing to wetland inflows are ungauged. The issue at Mulongo is the under simulation of low flow, while the high flows at the Ankoro gauging station are over-simulated. However, the pattern of the calibrated constraint indices in this region (Chapter 8) shows that the under simulation of low flow at Mulongo cannot be attributed to incremental sub-basins (between Bukama, Kapolowe and Mulongo gauging stations), because their Q90/MMQ constraint indices are even slightly above the original constraint ranges, but maintain a spatial consistency with sub-basins of other regions. Similarly, sub-basins located between Mulongo, Luvua and Ankoro gauging stations have high flow indices slightly below the original constraint ranges and therefore they are unlikely to be responsible for the over simulation of high flow at the Ankoro gauging station. These facts highlight the need for a further understanding of the complex wetland system of Kamalondo. Short-term data collection and monitoring programme are required. Important tributaries that drain to this wetland need to be monitored by installing water level loggers and periodically collecting flow data and river bathymetry. This programme should lead to the development of rating curves of wetland input tributaries. This would partially solve the unresolved uncertainty issues at the Ankoro and Mulongo gauging stations. The integrated modelling approach offers many opportunities in the Congo Basin. The quantified and modelled uncertainty helps to identify regions with high uncertainty and allows for the identification of various data collection and management strategies that can potentially contribute to the uncertainty reduction. The quantified channel-wetland exchanges contribute to the improvement of the overall knowledge of water resources estimation within the regions where the effects of wetlands are evident even at the monthly time scale. In contrast, ignoring uncertainty in the estimates of water resources availability means that water resources planning and management decisions in the Congo Basin will continue to be based on inadequate information and unquantified uncertainty, thus increasing the risk associated with water resources decision making. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-04
Microbial fuel cells for remediation of metal rich wastewater coupled with bioelectricity generation
- Authors: Mshoperi, Edith
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124112 , vital:35540
- Description: Expected release date-April 2022
- Full Text: false
- Date Issued: 2020
Microbial fuel cells for remediation of metal rich wastewater coupled with bioelectricity generation
- Authors: Mshoperi, Edith
- Date: 2020
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124112 , vital:35540
- Description: Expected release date-April 2022
- Full Text: false
- Date Issued: 2020
Environmental conflict resolution: a critical analysis of the role of interests and value
- Authors: Mweshi, John
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55842 , vital:26740
- Description: This thesis intends to contribute to an enhanced understanding of environmental conflicts and their resolution. To accomplish this task the thesis will ascertain the role that value and interests play in environmental conflicts in order to establish an adequate basis upon which they can be resolved. In the process, the thesis will also examine three different approaches, namely, the Standard Approach; the Environmental Impact Assessment (EIA) framework; and the Structured Decision Making (SDM) approach. First, the standard approach is informed by the understanding that focusing on interests instead of human values makes the resolution of conflicts more tractable. In contrast, this thesis argues that an exclusive focus on interests, in the context of environmental conflict resolution, is inadequate in some important respects because there are other factors to be considered such as the environmental impacts at the root of the conflict. Second, the thesis examines the focus on impacts that characterises EIAs. It argues that this approach remedies the limitations of the standard approach insofar as impacts are understood in terms of object value. However, the EIA approach does not provide much guidance on how to deal with conflicting human values. Third, taking into account the fact that the standard approach does not address the question of object value, while the EIA addresses object value but does not deal directly with human values, the thesis examines the SDM approach to environmental risk decisions. The thesis argues that while the SDM approach claims to deal with conflicts involving human values head-on, it does not provide a viable alternative in terms of environmental conflict resolution. This is because it fails to recognise the key distinction between human values and object value despite acknowledging the presence of multiple value dimensions as a major obstacle to value trade-offs and therefore to the resolution of value conflicts. Finally, the thesis recommends an adequate basis upon which environmental conflicts can be resolved.
- Full Text:
- Date Issued: 2015
- Authors: Mweshi, John
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55842 , vital:26740
- Description: This thesis intends to contribute to an enhanced understanding of environmental conflicts and their resolution. To accomplish this task the thesis will ascertain the role that value and interests play in environmental conflicts in order to establish an adequate basis upon which they can be resolved. In the process, the thesis will also examine three different approaches, namely, the Standard Approach; the Environmental Impact Assessment (EIA) framework; and the Structured Decision Making (SDM) approach. First, the standard approach is informed by the understanding that focusing on interests instead of human values makes the resolution of conflicts more tractable. In contrast, this thesis argues that an exclusive focus on interests, in the context of environmental conflict resolution, is inadequate in some important respects because there are other factors to be considered such as the environmental impacts at the root of the conflict. Second, the thesis examines the focus on impacts that characterises EIAs. It argues that this approach remedies the limitations of the standard approach insofar as impacts are understood in terms of object value. However, the EIA approach does not provide much guidance on how to deal with conflicting human values. Third, taking into account the fact that the standard approach does not address the question of object value, while the EIA addresses object value but does not deal directly with human values, the thesis examines the SDM approach to environmental risk decisions. The thesis argues that while the SDM approach claims to deal with conflicts involving human values head-on, it does not provide a viable alternative in terms of environmental conflict resolution. This is because it fails to recognise the key distinction between human values and object value despite acknowledging the presence of multiple value dimensions as a major obstacle to value trade-offs and therefore to the resolution of value conflicts. Finally, the thesis recommends an adequate basis upon which environmental conflicts can be resolved.
- Full Text:
- Date Issued: 2015
Formulation, development and assessment of devil’s claw loaded phyto-elastosomes in thermo-responsive hydrogels
- Authors: Ntemi, Pascal Vitalis
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164568 , vital:41139 , doi:10.21504/10962/164568
- Description: Thesis (PhD)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
- Authors: Ntemi, Pascal Vitalis
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164568 , vital:41139 , doi:10.21504/10962/164568
- Description: Thesis (PhD)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
The role of the Hop co-chaperone in the formation of Hsp90 complexes: chaperone link to glycolysis
- Authors: Maharaj, Shantal
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163593 , vital:41051 , doi:10.21504/10962/163593
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
- Authors: Maharaj, Shantal
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163593 , vital:41051 , doi:10.21504/10962/163593
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Date Issued: 2020
Wagon bridges of the Eastern Cape, c. 1840 – 1900: the contribution of engineering to infrastructural development
- Authors: Walters, Dennis Evelyn
- Date: 2018
- Subjects: Bridges Design and construction 19th century , Civil engineers South Africa Cape of Good Hope , Great Britain. Crown Agents' Office , Public works Great Britain Colonies , Wagon trains South Africa Cape of Good Hope
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63877 , vital:28500
- Description: This thesis examines an aspect of economic and technological history which has been little explored in South African history. It argues that the military subjugation and the economic development of the Cape Colony, and particularly of the Eastern Cape, were contingent upon good transportation. The geography of the country, which included relatively impassable mountains and numerous often flooded rivers, necessitated bridges as well as roads. Both were expensive. As a leader in industrial technology, Britain was well placed to extend bridge-building skills to its colonies. This thesis examines the processes by which a small and undeveloped colony strove to create an efficient technological infrastructure. As wagon traffic increased through progress, delays in crossing rivers became a hindrance leading to agitation for bridges. It will be shown that the construction of wagon bridges over the numerous rivers encountered in the Eastern Cape Colony was imperative for the initial free flow of military forces and for later commercial expansion as new towns were established. The eastward expansion was led by the military during the frontier wars followed by the Royal Engineers who built roads and bridges along the eastern frontier. The new Colonial Secretary John Montagu, who arrived in 1843, boosted the colonial finances by overhauling the administration. He established the Central Road Board, an organisation that would drive the building of mountain passes, roads and bridges. The Public Works Department succeeded the Central Road Board and with the financial intervention of the Crown Agents for the Colonies, carried on with an extensive programme of road and bridge building. From the 1870s wagon bridge building lagged behind the huge railway building enterprise in response to the opening up of the diamond and gold mines. The final quarter of the 19th century saw increased bridge building activity in the Eastern Cape with the construction of many iron lattice girder, stone masonry arch and timber trestle bridges. The surviving bridges remain as mute testimony to the skill and expertise of British engineers such as Lewis, Woodifield, Robinson, Fforde, Wakefield, Berkley, Grier, Newey, Westhoven and others.
- Full Text:
- Date Issued: 2018
- Authors: Walters, Dennis Evelyn
- Date: 2018
- Subjects: Bridges Design and construction 19th century , Civil engineers South Africa Cape of Good Hope , Great Britain. Crown Agents' Office , Public works Great Britain Colonies , Wagon trains South Africa Cape of Good Hope
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63877 , vital:28500
- Description: This thesis examines an aspect of economic and technological history which has been little explored in South African history. It argues that the military subjugation and the economic development of the Cape Colony, and particularly of the Eastern Cape, were contingent upon good transportation. The geography of the country, which included relatively impassable mountains and numerous often flooded rivers, necessitated bridges as well as roads. Both were expensive. As a leader in industrial technology, Britain was well placed to extend bridge-building skills to its colonies. This thesis examines the processes by which a small and undeveloped colony strove to create an efficient technological infrastructure. As wagon traffic increased through progress, delays in crossing rivers became a hindrance leading to agitation for bridges. It will be shown that the construction of wagon bridges over the numerous rivers encountered in the Eastern Cape Colony was imperative for the initial free flow of military forces and for later commercial expansion as new towns were established. The eastward expansion was led by the military during the frontier wars followed by the Royal Engineers who built roads and bridges along the eastern frontier. The new Colonial Secretary John Montagu, who arrived in 1843, boosted the colonial finances by overhauling the administration. He established the Central Road Board, an organisation that would drive the building of mountain passes, roads and bridges. The Public Works Department succeeded the Central Road Board and with the financial intervention of the Crown Agents for the Colonies, carried on with an extensive programme of road and bridge building. From the 1870s wagon bridge building lagged behind the huge railway building enterprise in response to the opening up of the diamond and gold mines. The final quarter of the 19th century saw increased bridge building activity in the Eastern Cape with the construction of many iron lattice girder, stone masonry arch and timber trestle bridges. The surviving bridges remain as mute testimony to the skill and expertise of British engineers such as Lewis, Woodifield, Robinson, Fforde, Wakefield, Berkley, Grier, Newey, Westhoven and others.
- Full Text:
- Date Issued: 2018
Preimages for SHA-1
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
- Authors: Motara, Yusuf Moosa
- Date: 2018
- Subjects: Data encryption (Computer science) , Computer security -- Software , Hashing (Computer science) , Data compression (Computer science) , Preimage , Secure Hash Algorithm 1 (SHA-1)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57885 , vital:27004
- Description: This research explores the problem of finding a preimage — an input that, when passed through a particular function, will result in a pre-specified output — for the compression function of the SHA-1 cryptographic hash. This problem is much more difficult than the problem of finding a collision for a hash function, and preimage attacks for very few popular hash functions are known. The research begins by introducing the field and giving an overview of the existing work in the area. A thorough analysis of the compression function is made, resulting in alternative formulations for both parts of the function, and both statistical and theoretical tools to determine the difficulty of the SHA-1 preimage problem. Different representations (And- Inverter Graph, Binary Decision Diagram, Conjunctive Normal Form, Constraint Satisfaction form, and Disjunctive Normal Form) and associated tools to manipulate and/or analyse these representations are then applied and explored, and results are collected and interpreted. In conclusion, the SHA-1 preimage problem remains unsolved and insoluble for the foreseeable future. The primary issue is one of efficient representation; despite a promising theoretical difficulty, both the diffusion characteristics and the depth of the tree stand in the way of efficient search. Despite this, the research served to confirm and quantify the difficulty of the problem both theoretically, using Schaefer's Theorem, and practically, in the context of different representations.
- Full Text:
- Date Issued: 2018
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