Photo-physicochemical characterization and in vitro Photodynamic Therapy Activity of Phthalocyanine-Graphene Quantum Dots Conjugates
- Authors: Nene, Lindokuhle Cindy
- Date: 2020
- Subjects: Photochemotherapy , Cancer -- Chemotherapy , Quantum dots , Graphene , Nanomedicine
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/140463 , vital:37891
- Description: This thesis reports on the preparation of several differently substituted Zn(II) phthalocyanine (Pc) complexes and their respective graphene quantum dots (GQDs) conjugates. In addition, Pc complexes substituted with biologically active molecules used in cancer therapeutics, namely: benzothiazole and morpholine, were also prepared and conjugated to GQDs. The photo-physicochemical properties were determined for both the complexes and their respective conjugates including the fluorescence/ triplet quantum yields and lifetimes as well as the singlet oxygen generating abilities. Upon conjugation to GQDs, the fluorescence of the Pc complexes decreased (insignificant decrease in some cases), with an increase in the triplet quantum yields. However, the singlet quantum yields of the Pcs in the conjugates did not show an increase with the increase in the triplet quantum yields. This is suspected to be due to the screening effect. The cytotoxicity of the complexes in vitro decreased upon conjugation, as a result of reduced actual number of Pc units provided in the conjugate for therapy. An increase in the efficacy upon quaternization was observed, and a relatively better performance was also observed for the cationic complex in combination with the biotin- functionalized GQDs, 7-GQDs-Biotin. Moreover, the cellular uptake of 7-GQDs-Biotin over 24 h was relatively high compared to complexes alone and other Pcs-GQDs conjugates.
- Full Text:
- Date Issued: 2020
- Authors: Nene, Lindokuhle Cindy
- Date: 2020
- Subjects: Photochemotherapy , Cancer -- Chemotherapy , Quantum dots , Graphene , Nanomedicine
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/140463 , vital:37891
- Description: This thesis reports on the preparation of several differently substituted Zn(II) phthalocyanine (Pc) complexes and their respective graphene quantum dots (GQDs) conjugates. In addition, Pc complexes substituted with biologically active molecules used in cancer therapeutics, namely: benzothiazole and morpholine, were also prepared and conjugated to GQDs. The photo-physicochemical properties were determined for both the complexes and their respective conjugates including the fluorescence/ triplet quantum yields and lifetimes as well as the singlet oxygen generating abilities. Upon conjugation to GQDs, the fluorescence of the Pc complexes decreased (insignificant decrease in some cases), with an increase in the triplet quantum yields. However, the singlet quantum yields of the Pcs in the conjugates did not show an increase with the increase in the triplet quantum yields. This is suspected to be due to the screening effect. The cytotoxicity of the complexes in vitro decreased upon conjugation, as a result of reduced actual number of Pc units provided in the conjugate for therapy. An increase in the efficacy upon quaternization was observed, and a relatively better performance was also observed for the cationic complex in combination with the biotin- functionalized GQDs, 7-GQDs-Biotin. Moreover, the cellular uptake of 7-GQDs-Biotin over 24 h was relatively high compared to complexes alone and other Pcs-GQDs conjugates.
- Full Text:
- Date Issued: 2020
Photocatalysis of 4-chloro and 4-nonylphenols using novel symmetric phthalocyanines and asymmetric porphyrin supported on polyacrylonitrite nanofibres
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
- Full Text:
- Date Issued: 2020
- Authors: Jones, Benjamin Martin
- Date: 2020
- Subjects: Nanoparticles , Phthalocyanines , Electrospinning , Porphyrins , Nanofibers , Photocatalysis , Photocatalysis -- Environmental aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164770 , vital:41163
- Description: This work explores the synthesis and characterisation of novel symmetrical phthalocyanines and novel asymmetric porphyrins that have been embedded or linked respectively,and electrospun into fibres for application in the photocatalysis of environmental pollutants. The phthalocyanines contain pyrrole moieties without hetero atom linkers to maintain a rigid structure. The porphyrin contains a carboxy moiety utilized to construct an amide bond between the complex and the polymer prior to the spinning process. The new compounds were characterized by elemental analyses, proton nuclear magnetic resonance (HNMR)Fourier-transform infrared spectroscopy (FTIR), MALDI-TOF and UV-vis spectroscopy. The general trends of fluorescence, triplet and singlet oxygen quantum yields are described as well as their appropriate lifetimes. The photocatalytic activity of phthalocyanine embedded fibres were compared against those that had been dyed. Unfortunately, during the degradation process, the dyed fibres leeched compound and the studies could not be continued. It was seen that the porphyrin fibres linked to the polymer showed the most efficient photocatalytic activity against 4-cholorphenol and 4-nonylphenol due to irradiation at lower wavelengths consequently having higher frequencies and transferring more energy.
- Full Text:
- Date Issued: 2020
Poor whites and the post-apartheid labour market: a study of perceptions and experiences of work among residents in a homeless shelter in Johannesburg
- Authors: Wollnik, Nadjeschda
- Date: 2020
- Subjects: Poor whites -- South Africa , Poor whites -- South Africa -- Atitudes , Shelters for the homeless -- South Africa , Unemployed -- South Africa -- Attitudes , Unemployed -- South Africa , South Africa -- Social conditions -- 1994- , South Africa -- Economic conditions -- 1991-
- Language: English
- Type: text , Thesis , Masters , MSocSci
- Identifier: http://hdl.handle.net/10962/148540 , vital:38748
- Description: Despite historical precedents, poverty among white people in South Africa remains an anomaly and a paradox. Likewise, the perceptions of work and employment among poor (under- and unemployed) whites in contemporary South Africa have received scant attention in the scholarly literature. Using the conceptual frameworks of critical whiteness studies and segmented labour market theory – as a way of combining subjective and objective considerations – this research seeks to describe and explain the perceptions and experiences of the labour market among poor whites living in a homeless shelter in Johannesburg. Eight respondents were chosen for extended, in-depth interviews in an effort to develop a fine-grained understanding of the pre-existing circumstances that affected their access to information and thus shaped their choices in the labour market, as well as to ascertain what they believed to be the barriers that they face in the labour market. The findings varied, with most of the interviewees seeing ‘being white’ as the reason for their poverty and unemployment, while others exhibited some awareness of the role of their lack of skills and qualifications in their capacity to compete in higher segments of the labour market. The findings were also varied in the sense that not all interviewees experienced poverty in the same manner, with some having been part of the middle class prior to becoming poor, while others having been poor their entire lives. It was also found that class or socio-economic status seemed to have a greater impact than race on the labour market prospects of the interviewees. It is argued that the perceptions of these poor whites, which are informed by their lack of information about the workings of the labour market, rather than their lack of qualifications or their race, most affected their prospects in the labour market. The mechanisms they rely on when seeking employment reveal a poor knowledge of the local labour market and the ways in which they think their skillsets match up to the types of jobs they desire. The lack of understanding of the South African labour market and the policies that are in place to redress the legacies of apartheid are among the factors influencing the lack of success these poor whites are experiencing in their search for work.
- Full Text:
- Date Issued: 2020
- Authors: Wollnik, Nadjeschda
- Date: 2020
- Subjects: Poor whites -- South Africa , Poor whites -- South Africa -- Atitudes , Shelters for the homeless -- South Africa , Unemployed -- South Africa -- Attitudes , Unemployed -- South Africa , South Africa -- Social conditions -- 1994- , South Africa -- Economic conditions -- 1991-
- Language: English
- Type: text , Thesis , Masters , MSocSci
- Identifier: http://hdl.handle.net/10962/148540 , vital:38748
- Description: Despite historical precedents, poverty among white people in South Africa remains an anomaly and a paradox. Likewise, the perceptions of work and employment among poor (under- and unemployed) whites in contemporary South Africa have received scant attention in the scholarly literature. Using the conceptual frameworks of critical whiteness studies and segmented labour market theory – as a way of combining subjective and objective considerations – this research seeks to describe and explain the perceptions and experiences of the labour market among poor whites living in a homeless shelter in Johannesburg. Eight respondents were chosen for extended, in-depth interviews in an effort to develop a fine-grained understanding of the pre-existing circumstances that affected their access to information and thus shaped their choices in the labour market, as well as to ascertain what they believed to be the barriers that they face in the labour market. The findings varied, with most of the interviewees seeing ‘being white’ as the reason for their poverty and unemployment, while others exhibited some awareness of the role of their lack of skills and qualifications in their capacity to compete in higher segments of the labour market. The findings were also varied in the sense that not all interviewees experienced poverty in the same manner, with some having been part of the middle class prior to becoming poor, while others having been poor their entire lives. It was also found that class or socio-economic status seemed to have a greater impact than race on the labour market prospects of the interviewees. It is argued that the perceptions of these poor whites, which are informed by their lack of information about the workings of the labour market, rather than their lack of qualifications or their race, most affected their prospects in the labour market. The mechanisms they rely on when seeking employment reveal a poor knowledge of the local labour market and the ways in which they think their skillsets match up to the types of jobs they desire. The lack of understanding of the South African labour market and the policies that are in place to redress the legacies of apartheid are among the factors influencing the lack of success these poor whites are experiencing in their search for work.
- Full Text:
- Date Issued: 2020
Post release evaluation of the distribution and efficacy of Eccritotarsus catarinensis and Eccritotarsus eichhorniae on Pontederia crassipes in South Africa
- Authors: Maseko, Zolile
- Date: 2020
- Subjects: Water hyacinth -- Biological control -- South Africa , Weeds -- Biological control -- South Africa , Miridae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/143046 , vital:38196
- Description: Biological control involves the release of new species into the environment and therefore, needs to be carefully monitored through post-release assessments which have been largely neglected in the science. Post-release evaluations of biological control programmes reveal whether the control agent has established and if it impacts weed demography, while cost-benefit analyses require a different set of data that show the magnitude on return on investment. The biological control effort on Pontederia crassipes in South Africa uses, amongst others, two species of mirid, Eccritotarsus catarinensis and E. eichhorniae. Initially, they were released as a single species, but were recently divided using molecular techniques. Eccritotarsus catarinensis was released in 1999, and E. eichhorniae in 2007. After many releases over two decades, there was need to assess where each species was established in the country. Molecular techniques proved to be valuable in identifying the two species as they are morphologically indistinguishable in the field. Therefore, molecular techniques should be routinely used for screening biocontrol agents, whether new or as re-introductions. Annual surveys of the mirid release sites around South Africa were undertaken between 2016 and 2019. At each site both insect and plant parameters were measured. Only E. catarinensis is established in the field in South Africa despite the multiple releases of E. eichhorniae at over 70 sites across the country, and E. catarinensis has established at only 22 of the 45 release sites accessed during this study. This thesis tested climate, interaction with other agents already on P. crassipes, and direct competition between the two mirid species as reasons for the lack of establishment of E. eichhorniae. The results of the country-wide surveys showed that climate and water trophic status were the major determinants in the establishment of E. catarinensis. Most of the establishment was recorded in the warmer regions of the country, however, a few populations of the mirid also established in cooler areas, thus demonstrating a degree of thermal plasticity, and possible microclimates as the mirids persisted at sites shaded by riparian vegetation. Stochastic events such as active herbicide campaigns, winter frosts, droughts and floods were responsible for the absence of the mirid at some sites. At some of the eutrophic sites, despite the abundance of E. catarinensis, plants still proliferated as the water trophic status facilitated plant growth, thus, plants were able to compensate for the damage inflicted by the mirid. A more intensive, monthly, post-release evaluation was conducted on the Kubusi River, Eastern Cape Province between 2016 and 2019. This is regarded as one of the cooler water hyacinth sites. Populations of biological control agents at this site fluctuated seasonally. At this site, cold winters caused frosting of the leaves of P. crassipes with the exception of plants growing under overhanging vegetation that provided a refuge for the mirid. But, cool temperatures in the winter months (May to August) severely reduced the populations of E. catarinensis that required a long recovery phase in spring. The consequence of this was that the plants grew unchecked from the onset of the growing season forming dense mats. Of the four agents at the Kubusi River site, Eccritotarsus catarinensis recovered slowest after winter, with lag phases ranging from two months to several months of the three-year period. The release of a suite of agents has implications on the agents themselves, where interactions between the agents can be important. Interactions between pairs and even multiple agents can have implications for biocontrol, where agents are either complimentary or interfere with each other. In this case, because E. catarinensis recovered the slowest of the four agents at the site, plants were of a poor quality by mid-summer resulting in low mirid populations. Competition in weed biological control could be expected to be strongest between pairs of agents that share the same niche, and this could be the reason why E. eichhorniae failed to establish at sites where E. catarinensis had already been established for several years. When the two mirids were combined in manipulated trials in a polytunnel, populations were lower compared to when the two mirids occurred separately. Under warm conditions, it is likely that E. eichhorniae would be the superior agent compared to E. catarinensis. The evaluations discussed in this thesis highlighted gaps in agent release methodology in multispecies settings, as well as the need for strategic augmentation pre- and post-winter. It is important to release agents that will complement each other rather than compete, therefore, when releasing agents in a multispecies setting, niche differentiation needs to be considered. Here it is concluded that the best practice for dealing with the mirids is that they should be released individually, and at sites that have no other biological control agents in order to ultimately assess their efficacy. Landscape level, long-term monitoring of biological control programmes shows the impact of the control programme at a broader scale and, are far more informative than short-term studies and at fewer sites. Long-term post-release evaluations should be mandatory in biological control programmes. Furthermore, these assessments will help develop new strategies or improve on existing ones, thus achieve greater success in control.
- Full Text:
- Date Issued: 2020
- Authors: Maseko, Zolile
- Date: 2020
- Subjects: Water hyacinth -- Biological control -- South Africa , Weeds -- Biological control -- South Africa , Miridae -- South Africa , Insects as biological pest control agents -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/143046 , vital:38196
- Description: Biological control involves the release of new species into the environment and therefore, needs to be carefully monitored through post-release assessments which have been largely neglected in the science. Post-release evaluations of biological control programmes reveal whether the control agent has established and if it impacts weed demography, while cost-benefit analyses require a different set of data that show the magnitude on return on investment. The biological control effort on Pontederia crassipes in South Africa uses, amongst others, two species of mirid, Eccritotarsus catarinensis and E. eichhorniae. Initially, they were released as a single species, but were recently divided using molecular techniques. Eccritotarsus catarinensis was released in 1999, and E. eichhorniae in 2007. After many releases over two decades, there was need to assess where each species was established in the country. Molecular techniques proved to be valuable in identifying the two species as they are morphologically indistinguishable in the field. Therefore, molecular techniques should be routinely used for screening biocontrol agents, whether new or as re-introductions. Annual surveys of the mirid release sites around South Africa were undertaken between 2016 and 2019. At each site both insect and plant parameters were measured. Only E. catarinensis is established in the field in South Africa despite the multiple releases of E. eichhorniae at over 70 sites across the country, and E. catarinensis has established at only 22 of the 45 release sites accessed during this study. This thesis tested climate, interaction with other agents already on P. crassipes, and direct competition between the two mirid species as reasons for the lack of establishment of E. eichhorniae. The results of the country-wide surveys showed that climate and water trophic status were the major determinants in the establishment of E. catarinensis. Most of the establishment was recorded in the warmer regions of the country, however, a few populations of the mirid also established in cooler areas, thus demonstrating a degree of thermal plasticity, and possible microclimates as the mirids persisted at sites shaded by riparian vegetation. Stochastic events such as active herbicide campaigns, winter frosts, droughts and floods were responsible for the absence of the mirid at some sites. At some of the eutrophic sites, despite the abundance of E. catarinensis, plants still proliferated as the water trophic status facilitated plant growth, thus, plants were able to compensate for the damage inflicted by the mirid. A more intensive, monthly, post-release evaluation was conducted on the Kubusi River, Eastern Cape Province between 2016 and 2019. This is regarded as one of the cooler water hyacinth sites. Populations of biological control agents at this site fluctuated seasonally. At this site, cold winters caused frosting of the leaves of P. crassipes with the exception of plants growing under overhanging vegetation that provided a refuge for the mirid. But, cool temperatures in the winter months (May to August) severely reduced the populations of E. catarinensis that required a long recovery phase in spring. The consequence of this was that the plants grew unchecked from the onset of the growing season forming dense mats. Of the four agents at the Kubusi River site, Eccritotarsus catarinensis recovered slowest after winter, with lag phases ranging from two months to several months of the three-year period. The release of a suite of agents has implications on the agents themselves, where interactions between the agents can be important. Interactions between pairs and even multiple agents can have implications for biocontrol, where agents are either complimentary or interfere with each other. In this case, because E. catarinensis recovered the slowest of the four agents at the site, plants were of a poor quality by mid-summer resulting in low mirid populations. Competition in weed biological control could be expected to be strongest between pairs of agents that share the same niche, and this could be the reason why E. eichhorniae failed to establish at sites where E. catarinensis had already been established for several years. When the two mirids were combined in manipulated trials in a polytunnel, populations were lower compared to when the two mirids occurred separately. Under warm conditions, it is likely that E. eichhorniae would be the superior agent compared to E. catarinensis. The evaluations discussed in this thesis highlighted gaps in agent release methodology in multispecies settings, as well as the need for strategic augmentation pre- and post-winter. It is important to release agents that will complement each other rather than compete, therefore, when releasing agents in a multispecies setting, niche differentiation needs to be considered. Here it is concluded that the best practice for dealing with the mirids is that they should be released individually, and at sites that have no other biological control agents in order to ultimately assess their efficacy. Landscape level, long-term monitoring of biological control programmes shows the impact of the control programme at a broader scale and, are far more informative than short-term studies and at fewer sites. Long-term post-release evaluations should be mandatory in biological control programmes. Furthermore, these assessments will help develop new strategies or improve on existing ones, thus achieve greater success in control.
- Full Text:
- Date Issued: 2020
Post-apartheid nostalgia and the future of the black visual archive
- Nsele, Zamansele Nsikakazi Busisiwe
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Date Issued: 2020
- Authors: Nsele, Zamansele Nsikakazi Busisiwe
- Date: 2020
- Subjects: Nostalgia in art , Memory in art , Africa -- In art , Africans in art , Fanon, Frantz, 1925-1961. Peau noire, masques blancs. English , South Africa -- In art , Black people in art
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167177 , vital:41444
- Description: The implications of nostalgia often strike a discordant note in post-apartheid discourse and this has opened up critical possibilities for research scholarship. For instance, Jacob Dlamini’s memoir Native Nostalgia entered the discursive fray in 2009, and it was subsequently followed by Derek Hook’s psychoanalytical approach in (Post) apartheid Conditions: Psychoanalysis and Social Formation in 2014. Notably, there is not yet a sustained and intensive research focus that has been conducted on post-apartheid forms of nostalgia within the discipline of art history and visual culture. I present this dissertation as a response to this gap. This thesis identifies mainly two competing nostalgias in post-apartheid South Africa. Through the analysis of selected artwork and media imagery, this dissertation critiques the connections of these nostalgias to the representation of the black figure in post-apartheid visual culture and the implications thereof. I argue that nostalgias for an apartheid-colonial-imperialist past operate through erasure and in the sanitisation of memory and as a result they render suffering indiscernible or in a sadomasochistic way consumes suffering as enjoyable. This thesis simultaneously critiques art work and visual representation that responds to South Africa’s nostalgia for the future: a restorative nostalgia that has emerged in the form of “rainbow nationalism”. This is a form of nostalgia that is underpinned by a dogged commitment to triumphalism and as a result erases the ongoing scenes of abjection. I use nostalgia and Afropessimism as analytical frameworks to argue that both real and visual representational forces work in tandem to restrain the future and this, I suggest is fulfilled by the transference of the black body from one state of unfreedom to next, resonating with a cyclical pattern. Frantz Fanon’s (1967) Black Skin White Mask forms the conceptual bedrock of my study, particularly his visual layout of “negrophobogenesis” and colonial temporality, which he describes as a “hellish cycle” or as an “infernal cycle” wherein the past overwhelms the present and ideas of the future.
- Full Text:
- Date Issued: 2020
Prediction of mass spectra for natural products using an ab initio approach
- Authors: Novokoza, Yolanda
- Date: 2020
- Subjects: Molecular dynamics , Molecular dynamics -- Computer simulation , Mass spectroscopy , Electron impact ionization
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167166 , vital:41443
- Description: Mass spectrometry (MS) is a technique that measures the fragmentation of molecules, dependent on the molecule’s chemical composition and structure, by first introducing a charge on the molecules. The instrument records the mass to charge ratio, but the energy from the ionization process causes the molecule to fragment. The resultant mass spectrum is highly indicative of not only the molecule analyzed, but also its chemical composition. MS is used in research and industry for both routine and research purposes. One such way to ionize molecules for MS is by bombarding the molecule with electrons which is the basis of electron impact mass spectrometry (EIMS). Although EIMS is widely used, prediction of electron impact mass spectra from first principles is a challenging problem due to a need to accurately determine the probability of different fragmentation pathways of a molecule. Ab initio molecular dynamics based methods are able to explore in an automatic fashion the energetically available fragmentation paths thus give reaction mechanisms in an unbiased way. The mass spectra of five molecules have been explored in work-flows leading to the prediction of mass spectra. These molecules include three natural products alpha-hispanolol, PFB oxime derivative and boronolide (for which experimental mass spectra were not available) and two compounds from the NIST database (for which experimental mass spectra were available). For each of these systems many random conformations were generated using the RDKit library. To all conformations random velocities were applied to each atom. Ab initio molecular dynamics was performed on each conformer, using these initial random velocities using CP2K software, at DFTB+ level at a variety of highly raised temperatures (to accelerate the formation of fragments) Fragmentation was monitored by iterating through all bonds, and identifying bond breakages during dynamics. Graph theoretical packages were used then to track distinct fragments generated. For each of these fragments, charges were determined from Mulliken analysis for all atoms on the fragment from the QM calculations and sum of atomic spin densities per fragment was also plotted. The fragment with the greatest charge (corresponding to the formation of a cation fragment) was taken for plotting on the mass spectrum. Finally, from the mass of the fragment and its elemental composition, the isotopic distribution for the fragment was determined, and this distribution was included by addition in to the mass spectrum. For all trajectories, the sum of all isotopic distributions determined the final mass spectrum.
- Full Text:
- Date Issued: 2020
- Authors: Novokoza, Yolanda
- Date: 2020
- Subjects: Molecular dynamics , Molecular dynamics -- Computer simulation , Mass spectroscopy , Electron impact ionization
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/167166 , vital:41443
- Description: Mass spectrometry (MS) is a technique that measures the fragmentation of molecules, dependent on the molecule’s chemical composition and structure, by first introducing a charge on the molecules. The instrument records the mass to charge ratio, but the energy from the ionization process causes the molecule to fragment. The resultant mass spectrum is highly indicative of not only the molecule analyzed, but also its chemical composition. MS is used in research and industry for both routine and research purposes. One such way to ionize molecules for MS is by bombarding the molecule with electrons which is the basis of electron impact mass spectrometry (EIMS). Although EIMS is widely used, prediction of electron impact mass spectra from first principles is a challenging problem due to a need to accurately determine the probability of different fragmentation pathways of a molecule. Ab initio molecular dynamics based methods are able to explore in an automatic fashion the energetically available fragmentation paths thus give reaction mechanisms in an unbiased way. The mass spectra of five molecules have been explored in work-flows leading to the prediction of mass spectra. These molecules include three natural products alpha-hispanolol, PFB oxime derivative and boronolide (for which experimental mass spectra were not available) and two compounds from the NIST database (for which experimental mass spectra were available). For each of these systems many random conformations were generated using the RDKit library. To all conformations random velocities were applied to each atom. Ab initio molecular dynamics was performed on each conformer, using these initial random velocities using CP2K software, at DFTB+ level at a variety of highly raised temperatures (to accelerate the formation of fragments) Fragmentation was monitored by iterating through all bonds, and identifying bond breakages during dynamics. Graph theoretical packages were used then to track distinct fragments generated. For each of these fragments, charges were determined from Mulliken analysis for all atoms on the fragment from the QM calculations and sum of atomic spin densities per fragment was also plotted. The fragment with the greatest charge (corresponding to the formation of a cation fragment) was taken for plotting on the mass spectrum. Finally, from the mass of the fragment and its elemental composition, the isotopic distribution for the fragment was determined, and this distribution was included by addition in to the mass spectrum. For all trajectories, the sum of all isotopic distributions determined the final mass spectrum.
- Full Text:
- Date Issued: 2020
Quantifying ecosystem restoration recovery and restoration practice following the biological control of invasive alien macrophytes in Southern Africa
- Authors: Motitsoe, Samuel Nkopane
- Date: 2020
- Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167519 , vital:41488
- Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
- Full Text:
- Date Issued: 2020
- Authors: Motitsoe, Samuel Nkopane
- Date: 2020
- Subjects: Salvinia molesta , Ceratophyllum demersum , Nymphaea mexicana , Invasive plants -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Restoration monitoring (Ecology) -- South Africa , Biolotical invasions -- Environmental aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167519 , vital:41488
- Description: Invasive alien aquatic plants (IAAP) species are known to have deleterious effects on the freshwater ecosystems they invade. This includes both socio-economic and ecologically important ecosystem goods and services. Thus, IAAP species are declared a serious threat, second only to habitat modification for causing a loss of aquatic biodiversity. Three control methods have been widely applied to control IAAP species invasion globally; mechanical, chemical and biological control. Both mechanical and chemical control methods are considered short-term and expensive, whereas biological control methods are regarded an effective and long-term solution for IAAP species control at the landscape level. But, little is known of the ecological recovery following the biological control of IAAP species, with mechanical control known to have had mixed success and chemical control to have non-targeted effects on aquatic ecosystems, causing harm to wildlife and human well-being. Biological control practitioners measure the success of biological control based on: (1) the biological control agents’ establishment and the negative impacts they impose on the targeted weed; and (2) the weeds biomass reduction and an increase in native macrophytes species. Arguably, measures of biological control success have been subjective and variable across the globe. Although some field studies have demonstrated biological control success to have positive socio-economic returns, there is little literature on ecological benefits. Furthermore, there is limited understanding on ecosystem recovery and possible restoration efforts following the biological control IAAP species, as compared to alien weeds in terrestrial and riparian ecosystems. Thus, this thesis aimed to quantify the ecological recovery i.e. aquatic biodiversity, ecosystem processes and trophic interactions following the management of Salvinia molesta in freshwater ecosystems. The research employed a suite of Before-After Control-Impact mesocosm and field studies to investigate the response of aquatic microalgae, macroinvertebrates and their interactions (food web structure and function) during S. molesta infestation and after mechanical and biological control. The mesocosm experiment (Before invasion, During invasion & After control) showed that both aquatic microalgae and macroinvertebrate diversity indices were reliable biological indicators of S. molesta ecological impacts and recovery following control. The restored treatment (100% S. molesta cover + biological control agents), demonstrated complete aquatic microalgae and macroinvertebrate recovery following biological control, similar to the control treatment (open water), where the degraded/impacted treatment (100% S. molesta cover with no biological control agents) showed a drastic decline in aquatic biodiversity and a complete shift in aquatic biota assemblage structure. Thus, the biological control effort by Cyrtobagous salviniae, the biological control agent for S. molesta, assisted in the recovery of aquatic biota following successful biological control. The field study (four field sites, two sites controlled mechanically and two biologically) investigated water quality, aquatic biodiversity and community trophic interactions (aquatic food web) “before and after” S. molesta control. The study showed a drastic decline in aquatic biodiversity (with three sites showing no record of aquatic macroinvertebrates, thus no biotic interactions during infestation) and poor water quality due to the shade-effect (light barrier due to floating S. molesta mats on the water surface) during the “before” S. molesta control phase. However, following both mechanical and biological control (“after” S. molesta control phase), there was a significant shift in abiotic and biotic ecosystem characteristics as compared to the “before” S. molesta control phase. Thus, rapid ecosystem recovery was apparent as a result of aquatic microalgae and macroinvertebrates recolonisation. Sites showed a normal functioning ecosystem where improved water quality, increased biodiversity, productivity and trophic interactions, was indicative of the return of biologically and functionally important species which were lost during the “before” S. molesta phase. Although the clear water state showed positive outcomes at Westlake River, these were short lived when the system was dominated by a cosmopolitan submerged Ceratophyllum demersum, and later replaced by a floating-leaved emergent IAAP Nymphaea mexicana. Each state was responsible for a significant shift in both biotic and abiotic characteristics, affirming macrophyte abilities to influence aquatic environments structure and functions. Furthermore, this event showed a clear example of a secondary invasion. Thus, a holistic IAAP species management strategy is necessary to restore previously invaded ecosystems and prevent subsequent secondary invasion and ecosystem degradation. In conclusion, the S. molesta shade-effect like any other free-floating IAAP species, was identified as the main degrading factor and responsible for water quality reduction, loss of aquatic diversity and shift in aquatic biota assemblage structure. Following S. molesta removal (or shade-effect elimination), there was a positive response to aquatic ecosystem species abundance, richness, diversity and community structure. Therefore, in combination, aquatic biota recolonisation rate and increases in biological and functional diversity were instrumental in the recovery of ecosystem structure and functions, following the control of S. molesta. Echoing existing literature, this thesis recommends: (1) IAAP species management programmes (mechanical and/or biological control) should not only aim to control the weed but also focus on ecosystems recovery and possible restoration goals; (2) biological control should be used where appropriate to combat free-floating IAAP species in freshwater ecosystems, followed by active introduction of native macrophyte propagules since they are limited by anthropogenic activities; and (3) more freshwater case studies are needed to add to our understanding of IAAP species management and restoration effort incorporating long-term monitoring.
- Full Text:
- Date Issued: 2020
Re-adjustment of masculinities and sexualities amongst first year male students at Rhodes University in the wake of the residence Consent Talk’s programme
- Authors: Ntisana, Thulani
- Date: 2020
- Subjects: Communication in higher education - South Africa -- Makhanda , Rape in universities and colleges -- South Africa -- Makhanda , Masculinity -- South Africa -- Makhanda , Male college students -- Social life and customs -- South Africa -- Makhanda , Male college students -- Sexual behavior -- South Africa -- Makhanda , Male college students -- Conduct of life -- South Africa -- Makhanda , Men -- Identity , Male domination (Social structure) , Patriarchy -- South Africa , Women -- Violence against -- South Africa , Social problems -- South Africa , Consent Talks , #RUreferencelist
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/148956 , vital:38790
- Description: This study seeks to understand how Rhodes University first-year male students adjusted and re-adjusted their masculinities and sexualities in light of the Consent Talk programme offered by the university, the aim of which is to liberate masculinities and femininities from patriarchal and dominant discourses. In the past 26 years, South Africa has seen an increase in academic research establishing causal links between boys, men, masculinities and a number of social ills such as the HIV/AIDs epidemic, violence against women, substance abuse, homophobia, gender-based violence and a lower pass rate amongst boys. This in turn inspired an increase in interventions seeking to involve boys and men in order to identify and address their role in combating gender based violence. These various forms of social deviances that have been linked to masculinity have indicated that young men's masculinity is in crisis and as a result needs great attention in order to address the social issues linked to them. Institutions of higher learning have proven to be microcosms of the larger society. Universities have become highly sexualised spaces; coercive sexual practices in heterosexual relationships are a norm, young women don't feel safe and have lost confidence in universities addressing their concerns. With the emergence of the #RUreferencelist in 2016, the spotlight fell on Rhodes University; young women challenged the rape culture and sexual assaults on campus. In 2016, staff members who are well-informed and educated on issues of gender, sexuality and rape initiated discussions with students in their residences; these discussions were later to be called the Consent Talks. This research makes use of Pierre Bourdieu’s critical theory in understanding how young men negotiate their masculinity within the field of higher education, at Rhodes University. Bourdieu’s three main concepts, field, habitus and capital are used to describe how young men negotiate their masculinity and how the field of gender intersects with the field of higher education. A qualitative paradigm has been employed. The study has collected data through the use of in-depth interviews to get a richer insight into the participants’ perspectives. There were 15 interviews conducted in total for this study, 14 were with first year male students, and one with a senior official of the University. The data was analysed through a qualitative thematic analysis. The findings of the research reveal that some of the participants were exposed to patriarchal and dominant forms of masculinity when growing up. However, most of the participants revealed they were also exposed to alternative masculinities. These were either taught or learnt at home, from family members, circumcision school, church or peers in society. Both the dominant and alternative masculinities were revealed in the discourses of what it means to be a man and in how the young men performed their masculinities. Furthermore, one of the major themes that emerged was that most of the young men in the study were raised by single mothers with mothers playing a significant role in encouraging healthy masculinities. The findings went on to reveal that families (mothers, fathers, older siblings and culture) play a role in socialising and shaping healthy masculinities. The acceptance or rejection of either dominant or alternative masculinities was influenced by an exposure to an environment that either encouraged or shunned either dominant or alternative masculinities. The findings further unveils that different societies are strongly identified with their own definitions of what it means to be a man and are not open to other definitions of masculinity. Moreover, most of the participants accepted the content of what was taught in the Consent Talks; however sought healthy participation, interaction and inclusion of female students. Lastly, the study has also revealed that knowledge of the consequences of breaking (the law) university’s policy does affect some change of behaviour in potential perpetrators.
- Full Text:
- Date Issued: 2020
- Authors: Ntisana, Thulani
- Date: 2020
- Subjects: Communication in higher education - South Africa -- Makhanda , Rape in universities and colleges -- South Africa -- Makhanda , Masculinity -- South Africa -- Makhanda , Male college students -- Social life and customs -- South Africa -- Makhanda , Male college students -- Sexual behavior -- South Africa -- Makhanda , Male college students -- Conduct of life -- South Africa -- Makhanda , Men -- Identity , Male domination (Social structure) , Patriarchy -- South Africa , Women -- Violence against -- South Africa , Social problems -- South Africa , Consent Talks , #RUreferencelist
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/148956 , vital:38790
- Description: This study seeks to understand how Rhodes University first-year male students adjusted and re-adjusted their masculinities and sexualities in light of the Consent Talk programme offered by the university, the aim of which is to liberate masculinities and femininities from patriarchal and dominant discourses. In the past 26 years, South Africa has seen an increase in academic research establishing causal links between boys, men, masculinities and a number of social ills such as the HIV/AIDs epidemic, violence against women, substance abuse, homophobia, gender-based violence and a lower pass rate amongst boys. This in turn inspired an increase in interventions seeking to involve boys and men in order to identify and address their role in combating gender based violence. These various forms of social deviances that have been linked to masculinity have indicated that young men's masculinity is in crisis and as a result needs great attention in order to address the social issues linked to them. Institutions of higher learning have proven to be microcosms of the larger society. Universities have become highly sexualised spaces; coercive sexual practices in heterosexual relationships are a norm, young women don't feel safe and have lost confidence in universities addressing their concerns. With the emergence of the #RUreferencelist in 2016, the spotlight fell on Rhodes University; young women challenged the rape culture and sexual assaults on campus. In 2016, staff members who are well-informed and educated on issues of gender, sexuality and rape initiated discussions with students in their residences; these discussions were later to be called the Consent Talks. This research makes use of Pierre Bourdieu’s critical theory in understanding how young men negotiate their masculinity within the field of higher education, at Rhodes University. Bourdieu’s three main concepts, field, habitus and capital are used to describe how young men negotiate their masculinity and how the field of gender intersects with the field of higher education. A qualitative paradigm has been employed. The study has collected data through the use of in-depth interviews to get a richer insight into the participants’ perspectives. There were 15 interviews conducted in total for this study, 14 were with first year male students, and one with a senior official of the University. The data was analysed through a qualitative thematic analysis. The findings of the research reveal that some of the participants were exposed to patriarchal and dominant forms of masculinity when growing up. However, most of the participants revealed they were also exposed to alternative masculinities. These were either taught or learnt at home, from family members, circumcision school, church or peers in society. Both the dominant and alternative masculinities were revealed in the discourses of what it means to be a man and in how the young men performed their masculinities. Furthermore, one of the major themes that emerged was that most of the young men in the study were raised by single mothers with mothers playing a significant role in encouraging healthy masculinities. The findings went on to reveal that families (mothers, fathers, older siblings and culture) play a role in socialising and shaping healthy masculinities. The acceptance or rejection of either dominant or alternative masculinities was influenced by an exposure to an environment that either encouraged or shunned either dominant or alternative masculinities. The findings further unveils that different societies are strongly identified with their own definitions of what it means to be a man and are not open to other definitions of masculinity. Moreover, most of the participants accepted the content of what was taught in the Consent Talks; however sought healthy participation, interaction and inclusion of female students. Lastly, the study has also revealed that knowledge of the consequences of breaking (the law) university’s policy does affect some change of behaviour in potential perpetrators.
- Full Text:
- Date Issued: 2020
Red and other short stories
- Authors: Harrison, Francis J
- Date: 2020
- Subjects: South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/141583 , vital:37987
- Description: Part A: Thesis (Creative Work);Part B: Portfolio. Final submission for the degree of Master of Arts in Creative Writing (MACW).
- Full Text:
- Date Issued: 2020
- Authors: Harrison, Francis J
- Date: 2020
- Subjects: South African fiction (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/141583 , vital:37987
- Description: Part A: Thesis (Creative Work);Part B: Portfolio. Final submission for the degree of Master of Arts in Creative Writing (MACW).
- Full Text:
- Date Issued: 2020
Reef fish associations with benthic habitats at a remote protected coral reef ecosystem in the Western Indian Ocean-Aldabra Atoll, Seychelles
- Authors: Haupt, Philip
- Date: 2020
- Subjects: Coral reef ecology -- Aldabra Islands (Seychelles) , Reef fishes -- Aldabra Islands (Seychelles) , Benthic animals -- Aldabra Islands (Seychelles)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141629 , vital:37991
- Description: The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef.
- Full Text:
- Date Issued: 2020
- Authors: Haupt, Philip
- Date: 2020
- Subjects: Coral reef ecology -- Aldabra Islands (Seychelles) , Reef fishes -- Aldabra Islands (Seychelles) , Benthic animals -- Aldabra Islands (Seychelles)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/141629 , vital:37991
- Description: The aim of the thesis is to develop an understanding of the associations between reef fish and benthic habitats and assess the modifying effects of environmental processes on these relationships at Aldabra, a pristine atoll in the Western Indian Ocean (WIO). Conducting research in pristine, or reference coral reef ecosystem, removes the impact of direct anthropogenic disturbances and provides essential information on natural ecosystem structure and functioning. Three primary hypotheses were tested: 1) Environmental drivers such as depth and exposure to wave energy determine the spatial distribution of benthic habitats; 2) The reef fish assemblage structure is explained by habitat at multiple scales and modified by the effects of environmental drivers such as depth, wave energy and cyclical temporal drivers such as time and tides; 3) The reef fish assemblage at Aldabra represents a pristine reef fish assemblage, comprising high levels of herbivores and predators. The research focussed on the benthic habitat on the seaward reefs between the shoreline and 50 m depth. The first objective was to characterise the benthic habitats on Aldabra Atoll’s seaward reefs and map their spatial distributions using remotely sensed imagery and ground truthing data. The second was to assess the influence of depth and exposure to wave energy on the distribution of benthic habitats. The third was to identify the most suitable standardised method to survey the reef fish assemblage structure on Aldabra’s, and fourth to determine the effect of tide and time of day on the reef fish assemblage. The fifth objective was to establish the association between reef fish assemblage structure and benthic habitats and to test how species-size influenced the scale of habitat at which the associations were most apparent. Four categories of geomorphic reef zones (reef flats (19.2 km2), top of the forereef slope (7.8 km2), deep forereef slope (11.6 km2), and reef platform (14.3 km2)) were manually delineated following the visual outlines of reef features from satellite imagery. The six broad-scale and twelve fine-scale benthic habitats were mapped using a supervised maximum likelihood classification and the spatial coverage of each determined. The broad-scale habitats were 1) Epilithic algal matrix, 2) Hard and soft (coral, 3) Rubble, 4) Macroalgae, 5) Seagrass and 6) Sand. Similarly, twelve fine-scale benthic habitats were characterised and mapped, for example, Hard coral (19 %) including massive and submassive forms with Millepora and Rhytisma. The broad-scale benthic habitat map had an overall producer accuracy of 54 % and fine-scale habitat map 29 %, which was consistent with studies using similar habitat classification methods. The prevailing wave energy, depth and the directional orientation of coral reefs (aspect) significantly influenced the probability of occurrence of each of the broad-scale benthic habitats, and there was a shift in peak probability of occurrence of all habitat categories to a greater depth with an increase in wave energy. The strong relationship of benthic habitats with depth and wave energy suggests that the distributions of benthic habitats are likely to change with sea-level rise and increased intensity and frequency of storms in future. Overall, 338 fish species from 51 families, including 14 species of elasmobranch were recorded using Baited Remote Underwater Video systems (BRUVs) and unbaited Remote Underwater Video systems (RUVS) from 231 samples. Fish were significantly more abundant when observed using BRUVs (119 ± 7) relative to RUVs (92 ± 7), and the assemblage structures were significantly different between the two sampling methods. Abundance and species richness of generalist carnivores and piscivores were significantly greater in BRUVs, while RUVs recorded significantly greater numbers of herbivores and more species of herbivore and corallivore. The results suggest that BRUVs are better suited when studying predatory fish which may not be detected without bait. However, when surveying a taxonomically and functionally diverse assemblage of fishes at a pristine reef, RUVs may provide a more accurate estimate of natural reef fish assemblage structure. Reef fish assemblages observed using RUVs were significantly different between morning-high-tide, midday-low-tide and evening-high-tide for all trophic groups. However, the reef fish assemblage structure observed using BRUVs was insensitive to change in tide and time of day, which may be explained by the attraction effect of bait dampening the effect of tide and time of day. While RUVs appear better to detect more subtle variations in fish assemblage structure, care needs to be taken when designing research programmes that use RUVs, as the sampling design should account for tide and time of day to avoid misinterpreting the cyclical variation, which may confound results. Reef fish assemblages were significantly different among habitats within geomorphic reef zones, broad-scale and fine-scale habitats. Species turnover rates were significantly different for all Actinopterygii size-class categories between the three scales of habitat. No marked differences in species turnover rates among habitats were detected for the majority of Elasmobranch size-class categories. The strong habitat dependency over various spatial scales indicates that effective conservation of Actinopterygii fish at Aldabra, and elsewhere in similar ecosystems requires protection of representative sets of benthic habitats. However, Elasmobranch conservation requires sufficiently large areas as these species utilise multiple habitats, over multiple scales, which are likely to exceed the confines of Aldabra’s reef.
- Full Text:
- Date Issued: 2020
Relevant knowledge: content analysis of research conducted by South African psychology masters students (2008-2012
- Authors: Whitehead, Tracey
- Date: 2020
- Subjects: Psychology -- Research -- South Africa , Psychology -- Study and teaching (Higher) -- South Africa , Psychology students -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167683 , vital:41503
- Description: In South Africa, Psychology has had a chequered past mainly due to its role in the justification of apartheid policies. Due to apartheid's socio-economic injustices, confidence in the applicability of psychological knowledge to South Africa's social problems was insufficient. Psychologists attempted to raise consciousness of the social relevance of psychology by contributing relevant knowledge and being reactive to social inequalities and related psychosocial issues affecting South Africa. This study aimed to conduct a content analysis of trends in research produced by Psychology Masters' students in the fields of Clinical, Counselling and Research psychology over a period of 5 years (2008-2012). The corpus of data was then compared with the key issues raised in the United Nations Development Programme's South Africa human development report (2003), along with a focus on articles published by Macleod (2004) and Macleod and Howell (2013). It emerged that Empirical Qualitative studies, based on post-modern frameworks, as well as HIV/AIDS, Knowledge Production, Assessment and Measurement and Programme development and evaluation, dominated psychological research. Participants were mainly urban, middle class adults living in the 3 wealthiest provinces. University students were the most popular participant group. While it is encouraging that students were attempting to engage with psychosocial issues, the limited number of key social issues addressed, the under-representation of certain sectors of the South African population, as well as the impact of socioeconomic status on well-being requires greater attention at Masters' level to ensure Psychology's psychosocial relevance.
- Full Text: false
- Date Issued: 2020
- Authors: Whitehead, Tracey
- Date: 2020
- Subjects: Psychology -- Research -- South Africa , Psychology -- Study and teaching (Higher) -- South Africa , Psychology students -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167683 , vital:41503
- Description: In South Africa, Psychology has had a chequered past mainly due to its role in the justification of apartheid policies. Due to apartheid's socio-economic injustices, confidence in the applicability of psychological knowledge to South Africa's social problems was insufficient. Psychologists attempted to raise consciousness of the social relevance of psychology by contributing relevant knowledge and being reactive to social inequalities and related psychosocial issues affecting South Africa. This study aimed to conduct a content analysis of trends in research produced by Psychology Masters' students in the fields of Clinical, Counselling and Research psychology over a period of 5 years (2008-2012). The corpus of data was then compared with the key issues raised in the United Nations Development Programme's South Africa human development report (2003), along with a focus on articles published by Macleod (2004) and Macleod and Howell (2013). It emerged that Empirical Qualitative studies, based on post-modern frameworks, as well as HIV/AIDS, Knowledge Production, Assessment and Measurement and Programme development and evaluation, dominated psychological research. Participants were mainly urban, middle class adults living in the 3 wealthiest provinces. University students were the most popular participant group. While it is encouraging that students were attempting to engage with psychosocial issues, the limited number of key social issues addressed, the under-representation of certain sectors of the South African population, as well as the impact of socioeconomic status on well-being requires greater attention at Masters' level to ensure Psychology's psychosocial relevance.
- Full Text: false
- Date Issued: 2020
Reliving it through pen
- Authors: Chidi, Tsosheletso
- Date: 2020
- Subjects: South African fiction (English) , Northern Sotho poetry
- Language: English , Northern Sotho
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/163566 , vital:41049
- Description: This document consists of two parts: PART A: English Half Thesis (Creative Work) PART B: Dual Language Portfolio (Sepedi and English). This thesis focuses on witnessing the trauma of rape, inability to move on, denial and attempt to forget, it draws attention also to emotional abuse in a place called home, death and place. My work is influenced by Carolyn Fourche’s anthology, Against Forgetting: Poetry of Witness, Adam Bradley and Andrew Dubois’s The Anthology of the Rap, as well as Lesego Rampolokeng poem “Welcome to New Consciousness”.
- Full Text:
- Date Issued: 2020
- Authors: Chidi, Tsosheletso
- Date: 2020
- Subjects: South African fiction (English) , Northern Sotho poetry
- Language: English , Northern Sotho
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/163566 , vital:41049
- Description: This document consists of two parts: PART A: English Half Thesis (Creative Work) PART B: Dual Language Portfolio (Sepedi and English). This thesis focuses on witnessing the trauma of rape, inability to move on, denial and attempt to forget, it draws attention also to emotional abuse in a place called home, death and place. My work is influenced by Carolyn Fourche’s anthology, Against Forgetting: Poetry of Witness, Adam Bradley and Andrew Dubois’s The Anthology of the Rap, as well as Lesego Rampolokeng poem “Welcome to New Consciousness”.
- Full Text:
- Date Issued: 2020
Resisting the ‘Native Informant’ trope in examples of African Diaspora art and literature
- Authors: Nuen, Tinika
- Date: 2020
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/131657 , vital:36708
- Description: This thesis draws attention to the existence of the ‘native informant’ trope in the African Diaspora. It argues that a strong emphasis towards studying diasporic groups in relation to their African origin revives, consequently, the colonial politics that underpin the continent as an unknown mythical place. In response to this issue, I introduce multidisciplinary case studies that highlight various artists and authors who resist and challenge the diasporic individual as the ‘native informant’. Their works reinterpret and redefine the relationship between African communities, their connection to the continent and their experiences of living abroad. Analysing the exhibitions Looking Both Ways, Africa Remix and Flow, I investigate their visual art discourses that interpret diasporic artists and their works as cultural embodiments of their African background. As a result, the three art shows marginalise other potential readings to view diasporic experiences. This thesis introduces three resistant themes that reconceive the diasporic person’s relationship to the African Diaspora based on language, spatial interaction and self-identification opposed to a geographic tie. The first theme (language) references Victor Ekpuk’s drawings and Isidore Okpewho’s novel Call Me By My Rightful Name to suggest a language based diasporic experience. The second theme (spatial interaction) looks at Emeka Ogboh’s sound installations and Teju Cole’s novel Open City. Both works examine a diasporic individual’s conflicted engagement with her place of origin. The third theme (self-identification) considers the individual-community relationship in Wura-Natasha Ogunji’s performance art and Chika Unigwe’s novel On Black Sisters’ Street. Each of these visual-literary pairs focus on various components that shape the African diasporic lifestyle. My research re-interprets the continent’s significance in the diaspora from a geographic construct to a socio-spiritual connection to a community. Firstly, it outlines the persistent issue of a colonial residue in Africa’s definition as a physical-cultural space, and secondly, it offers three alternative discourses to read diasporic identities outside a geographic framework. I argue that belonging is a social individual-collective effort rather than an anchor to a tangible environment.
- Full Text:
- Date Issued: 2020
- Authors: Nuen, Tinika
- Date: 2020
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/131657 , vital:36708
- Description: This thesis draws attention to the existence of the ‘native informant’ trope in the African Diaspora. It argues that a strong emphasis towards studying diasporic groups in relation to their African origin revives, consequently, the colonial politics that underpin the continent as an unknown mythical place. In response to this issue, I introduce multidisciplinary case studies that highlight various artists and authors who resist and challenge the diasporic individual as the ‘native informant’. Their works reinterpret and redefine the relationship between African communities, their connection to the continent and their experiences of living abroad. Analysing the exhibitions Looking Both Ways, Africa Remix and Flow, I investigate their visual art discourses that interpret diasporic artists and their works as cultural embodiments of their African background. As a result, the three art shows marginalise other potential readings to view diasporic experiences. This thesis introduces three resistant themes that reconceive the diasporic person’s relationship to the African Diaspora based on language, spatial interaction and self-identification opposed to a geographic tie. The first theme (language) references Victor Ekpuk’s drawings and Isidore Okpewho’s novel Call Me By My Rightful Name to suggest a language based diasporic experience. The second theme (spatial interaction) looks at Emeka Ogboh’s sound installations and Teju Cole’s novel Open City. Both works examine a diasporic individual’s conflicted engagement with her place of origin. The third theme (self-identification) considers the individual-community relationship in Wura-Natasha Ogunji’s performance art and Chika Unigwe’s novel On Black Sisters’ Street. Each of these visual-literary pairs focus on various components that shape the African diasporic lifestyle. My research re-interprets the continent’s significance in the diaspora from a geographic construct to a socio-spiritual connection to a community. Firstly, it outlines the persistent issue of a colonial residue in Africa’s definition as a physical-cultural space, and secondly, it offers three alternative discourses to read diasporic identities outside a geographic framework. I argue that belonging is a social individual-collective effort rather than an anchor to a tangible environment.
- Full Text:
- Date Issued: 2020
Resource recovery options in brewery effluent treatment using activated sludge and high rate algal ponds: assessing environmental impacts
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Date Issued: 2020
- Authors: Taylor, Richard Peter
- Date: 2020
- Subjects: Sewage -- Purification -- Activated sludge process , Sewage disposal plants , Sewage -- Purification -- Biological treatament , Sewage -- Purification -- Nitrogen removal , Brewery waste , Breweries -- Waste disposal , Microalgae -- Biotechnology , Algal biofuels
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/153746 , vital:39507
- Description: Wastewater treatment plants (WWTPs) are designed to clean effluents, but they also consume resources and produce waste. Various treatment technologies allow for the recovery of energy, nutrients and water from effluents turning this waste into products, which increases their sustainability and decreases the impact of WWTPs on the environment. There is a lack of literature which comprehensively compares the treatment performances, environmental impacts and beneficial downstream uses of the biomass generated by high rate algal pond (HRAP) and activated sludge (AS) treatment systems. This thesis aimed to compare (1) effluent treatment performance, (2) emissions and (3) downstream use of algae cultured in HRAP to sludge produced in AS and to obtain data to conduct a life cycle analysis (LCA) to compare the systems. The focus was on adding value to the effluent treatment process, while identifying the associated environmental impacts and contributing to the first ever zero-waste brewery effluent treatment system. Furthermore, these data were used to provide a basis to critically review and contribute to improving the methods used in the LCA of effluent treatment systems; particularly since this was the first wastewater treatment LCA that compared AS and HRAP using data collected from the same temporal and geographic location and from a single effluent stream. The electrical consumption water emission and land application of waste biomass caused the major environmental impacts of both treatment systems. The HRAP had less than 50 % of the electrical energy consumption (0.11±0.01 kW/m3 of effluent treated) compared to the AS system (0.29±0.11 kW/m3) which resulted in the technology having a lower climate change, photochemical oxidant formation, freshwater and marine ecotoxicity and fossil fuel depletion impact. It is imperative to understand the method of electrical energy (fossil fuel vs renewable) generation when conducting a LCA and deciding which technologies to use, since they have a major influence on the aforementioned impacts. The biogas yield of algal and sludge substrates was similar with an average gas production of 241 ml/g volatile solids fed. Biogas from algae fed digesters had a significantly higher methane content (64.73±0.81 %) and lower carbon dioxide content (22.94±0.24 %) when compared to WAS fed digesters (60.08±0.18 % and 27.37±0.43 %) respectively due to it being a less oxidised substrate. Swiss chard plants (Beta vulgaris) fertilised with anaerobically digested (AD) algae or sludge had a significantly higher mean biweekly yield (5.08±0.73 kg/m2) when compared to the inorganic-fertiliser control (3.45±0.89 kg/m2; p<0.0001). No difference was observed in the soil’s physical fertility when algae or sludge were applied to the soil (p>0.05). The HRAP produced more biomass (317.18±27.76 g/m3) than the AS (83.12±64.91 g/m3), which resulted in a significantly greater downstream production of biogas and fertiliser per volume of effluent treated. According to the LCA, this also resulted in the HRAP system having a higher terrestrial ecotoxicity, due to the greater volume of solids and thus heavy metals applied to the soil. This interpretation can be misleading, because the mass of heavy metals released into the environment is the same for both systems, with a greater portion being applied to the land in the HRAP scenario and discharged into fresh water in the case of AS. Future LCA models should clarify if these biomasses are going to be applied to a single piece of land or multiple sites as this will influence the risk of contamination via pollutant build up in the soil. The application of sludge or algae on soil increased the soil’s sodium concentration and sodium absorption ratio from 774.80±13.66 mg/kg to 952.17±34.89 mg/kg and 2.91±0.04 to 3.53±0.13, respectively. Regulations on the application of algae or sludge on agricultural soils should be altered to consider the limit values for sodium and future LCA’s associated with effluent treatment facilities should incorporate the possibility of soil contamination through sodium build-up. This work also conceptualised the importance of reporting water emissions in wastewater treatment LCA in as much detail as possible, because this had a significant influence on the eutrophication impacts on water systems. Reporting water emissions as total nitrogen underestimated downstream eutrophication impacts compared with those using nitrogen-species concentration (ammonia, nitrite, nitrate etc). A marine eutrophication sensitivity co-efficient should be included in future LCA models which accounts for the probability of nitrogen and phosphorus emissions entering the coastal environment as well as the vulnerability of the marine environment to eutrophication. Activated sludge systems are favourable for situations where space is limited, were there are inadequate options for biomass disposal (biomass not be used in agriculture or AD) and were electricity is generated from a renewable source; whereas, HRAP are more suitable under circumstances where electricity production relies on fossil fuel that carries a high environmental impact and where options are available to use the biomass for economic gain such as biogas and fertiliser production. This thesis contributes towards a zero-waste brewery effluent treated process. The HRAP and AS treated effluent for reuse in the brewery or in agricultural irrigation. The solids were anaerobically digested, and the carbon was recovered as a biogas, while the digestate was applied as an agricultural fertiliser. This allowed for the recovery of water, nutrients and carbon.
- Full Text:
- Date Issued: 2020
Rethinking corporate social responsibility in the mining industry: focusing on recipients’ perspectives
- Authors: Hlatshwayo, Thina M
- Date: 2020
- Subjects: Social responsibility of business -- South Africa -- Case studies , Mining industries -- Social aspects-- South Africa , Sustainable developmenet -- Social aspects -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/141711 , vital:37998
- Description: Views on the importance of companies engaging in CSR initiatives have been debated widely and critics of the concept continue to argue both locally and globally. The objective of the study was to gain an in-depth understanding of the recipients’ perspectives on their involvement in CSR projects implemented in their community by a chosen mining company and the successes and challenges of the project. A qualitative research approach was used for the study. Using nonprobability purpose sampling, a total of 15 participants from Lusikisiki were selected for the study. The data obtained was analysed using inductive thematic analysis. The results of the study were discussed based on the three research questions of the study which focused on recipients’ perspectives on their involvement in the projects and their perceptions on the successes and challenges of the projects. The study found that the chosen mining company made a significant contribution towards developing the community. Furthermore, the study found that recipients’ involvement in the projects enabled them to realize their assets in one of the projects as a result of the shift in approach by the organisation as the project progressed (Needs Based Approach to ABCD Approach). In addition, the study found that the successes of the projects changed the recipients’ perceptions of themselves and enabled them to actively engage in transforming their lives. However, the projects did face many challenges and recipients posited that more still needs to be done by organisations to develop communities and ensure that projects remain sustainable long after their partnership has dissolved.
- Full Text:
- Date Issued: 2020
- Authors: Hlatshwayo, Thina M
- Date: 2020
- Subjects: Social responsibility of business -- South Africa -- Case studies , Mining industries -- Social aspects-- South Africa , Sustainable developmenet -- Social aspects -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/141711 , vital:37998
- Description: Views on the importance of companies engaging in CSR initiatives have been debated widely and critics of the concept continue to argue both locally and globally. The objective of the study was to gain an in-depth understanding of the recipients’ perspectives on their involvement in CSR projects implemented in their community by a chosen mining company and the successes and challenges of the project. A qualitative research approach was used for the study. Using nonprobability purpose sampling, a total of 15 participants from Lusikisiki were selected for the study. The data obtained was analysed using inductive thematic analysis. The results of the study were discussed based on the three research questions of the study which focused on recipients’ perspectives on their involvement in the projects and their perceptions on the successes and challenges of the projects. The study found that the chosen mining company made a significant contribution towards developing the community. Furthermore, the study found that recipients’ involvement in the projects enabled them to realize their assets in one of the projects as a result of the shift in approach by the organisation as the project progressed (Needs Based Approach to ABCD Approach). In addition, the study found that the successes of the projects changed the recipients’ perceptions of themselves and enabled them to actively engage in transforming their lives. However, the projects did face many challenges and recipients posited that more still needs to be done by organisations to develop communities and ensure that projects remain sustainable long after their partnership has dissolved.
- Full Text:
- Date Issued: 2020
Rhodes University students’ experiences of living as students on National'Student Financial Aid Scheme (NSFAS) funding
- Authors: Mgwili, Thab’sile
- Date: 2020
- Subjects: National Student Financial Aid Scheme (South Africa) , Rhodes University -- Students -- Finance , Education, Higher -- South Africa , Education, Higher -- Finance -- South Africa , Student aid -- South Africa , Welfare state -- South Africa , Student financial aid administration -- South Africa , Student financial aid administration -- South Africa -- Case studies
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/147961 , vital:38697
- Description: This study explores Rhodes University students’ experiences of living as students on National Student Financial Aid Scheme (NSFAS) funding. The Marxist theoretical framework critique of neoliberalism and welfare systems is used. The Marxist theory is the main theory that underpins the study. Eighteen participants were involved in an in-depth interview process. Out of 18 participants, one is a staff member at Rhodes University Financial Aid Office. The key findings of this research revealed the unfavorable circumstances of students on NSFAS at Rhodes University. Secondly, it was discovered that students shared similar sentiments as NSFAS and DHET: They recognize the major areas that need to be addressed by NSFAS. Thirdly, NSFAS had to some extent made a positive contribution to the higher education sector. Suggestions have been made on how my study may be improved to yield even better results.
- Full Text:
- Date Issued: 2020
- Authors: Mgwili, Thab’sile
- Date: 2020
- Subjects: National Student Financial Aid Scheme (South Africa) , Rhodes University -- Students -- Finance , Education, Higher -- South Africa , Education, Higher -- Finance -- South Africa , Student aid -- South Africa , Welfare state -- South Africa , Student financial aid administration -- South Africa , Student financial aid administration -- South Africa -- Case studies
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/147961 , vital:38697
- Description: This study explores Rhodes University students’ experiences of living as students on National Student Financial Aid Scheme (NSFAS) funding. The Marxist theoretical framework critique of neoliberalism and welfare systems is used. The Marxist theory is the main theory that underpins the study. Eighteen participants were involved in an in-depth interview process. Out of 18 participants, one is a staff member at Rhodes University Financial Aid Office. The key findings of this research revealed the unfavorable circumstances of students on NSFAS at Rhodes University. Secondly, it was discovered that students shared similar sentiments as NSFAS and DHET: They recognize the major areas that need to be addressed by NSFAS. Thirdly, NSFAS had to some extent made a positive contribution to the higher education sector. Suggestions have been made on how my study may be improved to yield even better results.
- Full Text:
- Date Issued: 2020
Satire in J.J. R. Jolobe's literary works : a critique in relation to contemporary South Africa
- Authors: Benayo, Xolela
- Date: 2020
- Subjects: Jolobe, James J. R. , Xhosa literature -- History and criticism , Xhosa poetry -- History and criticism , Humor in literature , Xhosa literature -- Humor , Xhosa language
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/161762 , vital:40667
- Description: J.J.R. Jolobe is regarded as one of the individuals who made a valuable contribution to the development of isiXhosa literature through his works, notably in his poetry (Ilitha, Umyezo; Jolobe 1936). His poetry ranges from abstract subjects to more philosophical matters. This study is aimed at decoding the manner in which he employs satire to conscientise African people of the then horrible situation that they were facing. With that said, poetry will not be the only work that this thesis analyses in the process of evaluating Jolobe’s satire; his essays will also be examined (Amavo; Jolobe 1940). Based on the writings of various authors specialising in the subject, satire has been deemed to be a style of literary writing, one which involves invective satire. For the researcher, that statement will be rebutted, as it will be argued that the mode of satire need not be wholly invective. Jolobe’s light-hearted satire not only showcases the amusing side of his writings, but also indicates the seriousness with which they were intended. Themes covered in Jolobe’s satire have inspired the researcher to evaluate these literary texts in relation to modern contexts, especially when it comes to the relationship between the lines of the author’s experience and the public. With that said, the social role of satire is something that one cannot deny. One could therefore say that there is an urgent need for African satirists to face the existing social and economic reality as authentically as possible. The voice of a satirist should also echo the voice of their society as a whole. Satirical study in post-colonial Africa, in South Africa in particular, is useful due to the idea that the works of the likes of Jolobe may diminish in significance due to neo-colonialism. In fact, this is the point which is considered in this study of Jolobe’s satire. This study also examines stages afforded to the development of satire in Africa, especially in the post-colonial era. The purpose is to identify the effects of satire that are related to socio-political as well as religious factors. These factors are often seen as those that play a vital role is one’s personal morals, and those that are meant to shape the whole community. Jolobe addresses imperialism and the class struggle, which speaks to the society’s loyalties regarding the mobilization toward realizing the dream of being independent. This speaks to the works analysed, revealing protests against oppression and exploitation by imperialists; such works show how inhumane people could be against those who they deem to be beneath their standards. Researchers like Mahlasela (1973), Sirayi (1985), Kwetana (2000) and Khumalo (2015) are amongst those who have made it a point to study Jolobe to ensure that these works are kept alive, along with their significance. Other prospective researchers can follow suite in researching the great Jolobe. In ensuring that the aims of this study come to light, the researcher will be using socialist realism as a way of seeing that the works of Jolobe are realistic in nature. With that said, there will be an exploration of allegoric satire. Satiric allegory will be evaluated with regard to the view that it represents a unique slant on satire, whereby it deems satire to be more than just a supportive method of literary criticism. This allows the researcher to hold the view that satire should not be a restrictive framework when dealing with African literature. Satire as a modern form of criticism can be viewed as having an element of humanism, which would result in the satirist doing all he can to make sure that what is satirized is not isolated from the struggle of the community. It is for the above-mentioned reasons that we see a big challenge in the future development of satiric discourse in African literature.
- Full Text:
- Date Issued: 2020
- Authors: Benayo, Xolela
- Date: 2020
- Subjects: Jolobe, James J. R. , Xhosa literature -- History and criticism , Xhosa poetry -- History and criticism , Humor in literature , Xhosa literature -- Humor , Xhosa language
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/161762 , vital:40667
- Description: J.J.R. Jolobe is regarded as one of the individuals who made a valuable contribution to the development of isiXhosa literature through his works, notably in his poetry (Ilitha, Umyezo; Jolobe 1936). His poetry ranges from abstract subjects to more philosophical matters. This study is aimed at decoding the manner in which he employs satire to conscientise African people of the then horrible situation that they were facing. With that said, poetry will not be the only work that this thesis analyses in the process of evaluating Jolobe’s satire; his essays will also be examined (Amavo; Jolobe 1940). Based on the writings of various authors specialising in the subject, satire has been deemed to be a style of literary writing, one which involves invective satire. For the researcher, that statement will be rebutted, as it will be argued that the mode of satire need not be wholly invective. Jolobe’s light-hearted satire not only showcases the amusing side of his writings, but also indicates the seriousness with which they were intended. Themes covered in Jolobe’s satire have inspired the researcher to evaluate these literary texts in relation to modern contexts, especially when it comes to the relationship between the lines of the author’s experience and the public. With that said, the social role of satire is something that one cannot deny. One could therefore say that there is an urgent need for African satirists to face the existing social and economic reality as authentically as possible. The voice of a satirist should also echo the voice of their society as a whole. Satirical study in post-colonial Africa, in South Africa in particular, is useful due to the idea that the works of the likes of Jolobe may diminish in significance due to neo-colonialism. In fact, this is the point which is considered in this study of Jolobe’s satire. This study also examines stages afforded to the development of satire in Africa, especially in the post-colonial era. The purpose is to identify the effects of satire that are related to socio-political as well as religious factors. These factors are often seen as those that play a vital role is one’s personal morals, and those that are meant to shape the whole community. Jolobe addresses imperialism and the class struggle, which speaks to the society’s loyalties regarding the mobilization toward realizing the dream of being independent. This speaks to the works analysed, revealing protests against oppression and exploitation by imperialists; such works show how inhumane people could be against those who they deem to be beneath their standards. Researchers like Mahlasela (1973), Sirayi (1985), Kwetana (2000) and Khumalo (2015) are amongst those who have made it a point to study Jolobe to ensure that these works are kept alive, along with their significance. Other prospective researchers can follow suite in researching the great Jolobe. In ensuring that the aims of this study come to light, the researcher will be using socialist realism as a way of seeing that the works of Jolobe are realistic in nature. With that said, there will be an exploration of allegoric satire. Satiric allegory will be evaluated with regard to the view that it represents a unique slant on satire, whereby it deems satire to be more than just a supportive method of literary criticism. This allows the researcher to hold the view that satire should not be a restrictive framework when dealing with African literature. Satire as a modern form of criticism can be viewed as having an element of humanism, which would result in the satirist doing all he can to make sure that what is satirized is not isolated from the struggle of the community. It is for the above-mentioned reasons that we see a big challenge in the future development of satiric discourse in African literature.
- Full Text:
- Date Issued: 2020
Seasonal trends of rainfall intensity, ground cover and sediment dynamics in the Little Pot River and Gqukunqa River catchments, South Africa
- Authors: Herd-Hoare, Sean
- Date: 2020
- Subjects: Land degradation -- Control -- South Africa -- Eastern Cape , Vegetation mapping -- South Africa -- Eastern Cape , Rain and rainfall -- South Africa -- Eastern Cape , Gqukunqa River catchment (South Africa) , Little Pot River catchment (South Africa) , Tsitsa River catchment (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146288 , vital:38512
- Description: Natural rangelands provide a variety of ecosystem services including livestock production which occurs on land under freehold land tenure and on land under communal tenure. There is an ongoing debate around the extent to which land degradation is occurring on these rangelands under different land management and land tenure systems and what the main degradation drivers are. Over-grazing, rainfall and soil type are key drivers of rangeland dynamics and the resultant sediment yield in the river systems, however, over-grazing is an outcome of land management while rainfall and soil type are natural drivers. This study explores the relationship between rainfall and daily sediment flux as well as the seasonal trends of vegetation cover and the study is part of a greater research effort called the Tsitsa Project which is based in the Tsitsa River catchment (near Maclear, Eastern Cape, South Africa). The Tsitsa Project aims at developing and managing both land and water in a sustainable way by improving the land, water and lives of people living in the Tsitsa River catchment. The restoration efforts of the Tstisa Project will aid in extending the lifespan of both the proposed dams on the Tsitsa River. The Tsitsa River catchment is characterised by grasslands, steep topography, highly erodible soils with many large gullies present and a very high sediment yield in the Tsitsa River which allowed for the exploration of some of the system drivers of sediment yield in this catchment. The study involved two sub-catchments of the Upper Tsitsa River catchment of different land management strategies: one dominated by commercial livestock farms (Little Pot River catchment) and one dominated by communal rangelands (Gqukunqa River catchment). The aim of this study was to determine the seasonal trends of rainfall intensity, ground cover and sediment dynamics in the Little Pot River and Gqukunqa River catchments. The purpose of the findings was to improve management strategies in degraded areas and catchments. In order to achieve this aim a variety of field and desktop methods were used. Field methods involved measuring variables including: vegetation biomass, vegetation cover, soil surface hardness, biocrust cover and slope angle for a range of Normalized Difference Vegetation Index (NDVI) values from the Sentinel-2A sensor. The study assessed the system response of the field variables in both catchments over one rainfall season (2018-2019). Desktop methods included various NDVI analyses as well as analyses of trends and relationships between vegetation dynamics, rainfall and sediment. The relationship between erosive rainfall events, daily rainfall, antecedent rainfall and daily sediment flux was explored over the time period of January 2016 to January 2019 and October 2015 to January 2019 for the Little Pot River catchment and the Gqukunqa River catchment respectively. NDVI was explored as a proxy for vegetation cover to extrapolate across the catchments and monitoring period. NDVI was found to have a weak positive relationship with vegetation cover and biomass (R2 values ranged from 0,04 to 0,525). Mean monthly catchment NDVI values, biomass and vegetation cover increased throughout the wet season of 2018-2019 in both catchments. Mean monthly NDVI values increased from 0,26 to 0,55 in the Little Pot River catchment and from 0,29 to 0,53 in the Gqukunqa River catchment over the course of the 2018-2019 wet season. NDVI, biomass and vegetation cover was found to be higher on south-facing slopes than north-facing slopes in both catchments for the majority of the wet season. The Gqukunqa River has significantly higher daily sediment fluxes than the Little Pot River despite similar NDVI and rainfall intensities which is owed to the dispersive soils in the Gqukunqa River catchment. Soil surface hardness results were inconclusive due to rainfall before or during every field trip which changed the properties of the soil. The largest erosive rainfall, daily rainfall and daily sediment events occurred from January to March each wet season in both catchments. Rainfall intensity and sediment fluxes were found to have a weak relationship, however, there was a stronger relationship found between antecedent rainfall and sediment flux. The larger daily sediment fluxes in each catchment often did not result from an erosive rainfall event on the same day but rather from multiple days of rainfall which can result in saturated soils and runoff leading to surface and sub-surface erosion. The possibility of sub-surface erosion via chemical processes contributing to the larger sediment events was also explored to explain the stronger relationship between antecedent rainfall and daily sediment flux.
- Full Text:
- Date Issued: 2020
- Authors: Herd-Hoare, Sean
- Date: 2020
- Subjects: Land degradation -- Control -- South Africa -- Eastern Cape , Vegetation mapping -- South Africa -- Eastern Cape , Rain and rainfall -- South Africa -- Eastern Cape , Gqukunqa River catchment (South Africa) , Little Pot River catchment (South Africa) , Tsitsa River catchment (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/146288 , vital:38512
- Description: Natural rangelands provide a variety of ecosystem services including livestock production which occurs on land under freehold land tenure and on land under communal tenure. There is an ongoing debate around the extent to which land degradation is occurring on these rangelands under different land management and land tenure systems and what the main degradation drivers are. Over-grazing, rainfall and soil type are key drivers of rangeland dynamics and the resultant sediment yield in the river systems, however, over-grazing is an outcome of land management while rainfall and soil type are natural drivers. This study explores the relationship between rainfall and daily sediment flux as well as the seasonal trends of vegetation cover and the study is part of a greater research effort called the Tsitsa Project which is based in the Tsitsa River catchment (near Maclear, Eastern Cape, South Africa). The Tsitsa Project aims at developing and managing both land and water in a sustainable way by improving the land, water and lives of people living in the Tsitsa River catchment. The restoration efforts of the Tstisa Project will aid in extending the lifespan of both the proposed dams on the Tsitsa River. The Tsitsa River catchment is characterised by grasslands, steep topography, highly erodible soils with many large gullies present and a very high sediment yield in the Tsitsa River which allowed for the exploration of some of the system drivers of sediment yield in this catchment. The study involved two sub-catchments of the Upper Tsitsa River catchment of different land management strategies: one dominated by commercial livestock farms (Little Pot River catchment) and one dominated by communal rangelands (Gqukunqa River catchment). The aim of this study was to determine the seasonal trends of rainfall intensity, ground cover and sediment dynamics in the Little Pot River and Gqukunqa River catchments. The purpose of the findings was to improve management strategies in degraded areas and catchments. In order to achieve this aim a variety of field and desktop methods were used. Field methods involved measuring variables including: vegetation biomass, vegetation cover, soil surface hardness, biocrust cover and slope angle for a range of Normalized Difference Vegetation Index (NDVI) values from the Sentinel-2A sensor. The study assessed the system response of the field variables in both catchments over one rainfall season (2018-2019). Desktop methods included various NDVI analyses as well as analyses of trends and relationships between vegetation dynamics, rainfall and sediment. The relationship between erosive rainfall events, daily rainfall, antecedent rainfall and daily sediment flux was explored over the time period of January 2016 to January 2019 and October 2015 to January 2019 for the Little Pot River catchment and the Gqukunqa River catchment respectively. NDVI was explored as a proxy for vegetation cover to extrapolate across the catchments and monitoring period. NDVI was found to have a weak positive relationship with vegetation cover and biomass (R2 values ranged from 0,04 to 0,525). Mean monthly catchment NDVI values, biomass and vegetation cover increased throughout the wet season of 2018-2019 in both catchments. Mean monthly NDVI values increased from 0,26 to 0,55 in the Little Pot River catchment and from 0,29 to 0,53 in the Gqukunqa River catchment over the course of the 2018-2019 wet season. NDVI, biomass and vegetation cover was found to be higher on south-facing slopes than north-facing slopes in both catchments for the majority of the wet season. The Gqukunqa River has significantly higher daily sediment fluxes than the Little Pot River despite similar NDVI and rainfall intensities which is owed to the dispersive soils in the Gqukunqa River catchment. Soil surface hardness results were inconclusive due to rainfall before or during every field trip which changed the properties of the soil. The largest erosive rainfall, daily rainfall and daily sediment events occurred from January to March each wet season in both catchments. Rainfall intensity and sediment fluxes were found to have a weak relationship, however, there was a stronger relationship found between antecedent rainfall and sediment flux. The larger daily sediment fluxes in each catchment often did not result from an erosive rainfall event on the same day but rather from multiple days of rainfall which can result in saturated soils and runoff leading to surface and sub-surface erosion. The possibility of sub-surface erosion via chemical processes contributing to the larger sediment events was also explored to explain the stronger relationship between antecedent rainfall and daily sediment flux.
- Full Text:
- Date Issued: 2020
Sexual attraction and mating compatibility between Thaumatotibia leucotreta populations and implications for semiochemical dependent technologies
- Authors: Upfold, Jennifer Kate
- Date: 2020
- Subjects: Cryptophlebia leucotreta -- South Africa , Cryptophlebia leucotreta -- Reproduction , Citrus -- Disease and pests -- Control -- South Africa , Insect sterilization -- South Africa , Pheromones , Pheromone traps
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/148526 , vital:38747
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick), is the most important pest for the cultivation of citrus in South Africa. False codling moth is indigenous to southern Africa and is a regulated pest of many international markets for phytosanitary concerns. Considerable research efforts have been invested in the past decades to develop semiochemcial technologies, such as monitoring with sex pheromones, attract-and-kill, mating disruption and the sterile insect technique. One of the potential obstacles identified with semiochemical control is the differences in the ratio of the compounds comprising the sex pheromone at different geographical locations, resulting in what is known as regional attraction. This has been identified in FCM populations from three different countries, however, regional attraction within South African FCM populations was unknown. Therefore, the study assessed the genetic integrity of five laboratory-reared FCM populations originating from geographically isolated populations in South Africa using the AFLP technique in order to assess regional attractiveness within the country. The results found isolated populations from Addo, Citrusdal, Marble Hall, Nelspruit and a fifth group found to be closely related to Addo and Citrusdal called the ‘Old’ colony. These five genetically isolated populations as well as a population from Xsit (Pty) Ltd, used for the sterile insect technique (SIT), were used in regional attractiveness trials. Males were significantly (P = <0.05) more attracted to females originating from the same population. No significant attraction could be determined from the sterile males, as the recapture rates in the trap were too low. Furthermore, regional attractiveness was assessed through choice/ no-choice mating compatibility trials. Significant sexual isolation (ISI) occurred between mating combinations Addo × Nelspruit (ISI = 0,13; t2 = 6.23; p = 0.02), Addo × Marble Hall (ISI = 0,11; t2 = 4.72; p = 0.04), Citrusdal × Nelspruit (ISI = 0,11; t2 = 4.95; p = 0.04), and Citrusdal × Marble Hall (ISI = 0,12; t2 = 4.31; p = 0.04). In these combinations, Addo and Citrusdal males were found to have outcompeted Nelspruit and Marble Hall males for more mating events. Significant sexual isolation was also recorded for Sterile × Marble Hall (ISI = 0.12; t2 = 4.98; p =0.01) and Sterile × Citrusdal (ISI = 0.13; t2 = 3.96; p = 0.01) populations. The male relative performance index was significant in both combinations, indicating that non-sterile laboratory males outcompeted the sterile males in these two combinations. When given no choice, evaluated as spermatophore transfer/ female/ 48h, all males (including sterile) were successful in transferring spermatophores to all FCM populations, with no significant differences. These results indicate that there may be incipient pre-isolation mechanisms affected by local natural selection, resulting in localised sexual attraction via differences in the sex pheromone ratios. These findings provide important information for semiochemical technologies and the implication of these results with regard to monitoring with sex pheromones, attract-and-kill, mating disruption and sterile insect technique are discussed.
- Full Text:
- Date Issued: 2020
- Authors: Upfold, Jennifer Kate
- Date: 2020
- Subjects: Cryptophlebia leucotreta -- South Africa , Cryptophlebia leucotreta -- Reproduction , Citrus -- Disease and pests -- Control -- South Africa , Insect sterilization -- South Africa , Pheromones , Pheromone traps
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/148526 , vital:38747
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick), is the most important pest for the cultivation of citrus in South Africa. False codling moth is indigenous to southern Africa and is a regulated pest of many international markets for phytosanitary concerns. Considerable research efforts have been invested in the past decades to develop semiochemcial technologies, such as monitoring with sex pheromones, attract-and-kill, mating disruption and the sterile insect technique. One of the potential obstacles identified with semiochemical control is the differences in the ratio of the compounds comprising the sex pheromone at different geographical locations, resulting in what is known as regional attraction. This has been identified in FCM populations from three different countries, however, regional attraction within South African FCM populations was unknown. Therefore, the study assessed the genetic integrity of five laboratory-reared FCM populations originating from geographically isolated populations in South Africa using the AFLP technique in order to assess regional attractiveness within the country. The results found isolated populations from Addo, Citrusdal, Marble Hall, Nelspruit and a fifth group found to be closely related to Addo and Citrusdal called the ‘Old’ colony. These five genetically isolated populations as well as a population from Xsit (Pty) Ltd, used for the sterile insect technique (SIT), were used in regional attractiveness trials. Males were significantly (P = <0.05) more attracted to females originating from the same population. No significant attraction could be determined from the sterile males, as the recapture rates in the trap were too low. Furthermore, regional attractiveness was assessed through choice/ no-choice mating compatibility trials. Significant sexual isolation (ISI) occurred between mating combinations Addo × Nelspruit (ISI = 0,13; t2 = 6.23; p = 0.02), Addo × Marble Hall (ISI = 0,11; t2 = 4.72; p = 0.04), Citrusdal × Nelspruit (ISI = 0,11; t2 = 4.95; p = 0.04), and Citrusdal × Marble Hall (ISI = 0,12; t2 = 4.31; p = 0.04). In these combinations, Addo and Citrusdal males were found to have outcompeted Nelspruit and Marble Hall males for more mating events. Significant sexual isolation was also recorded for Sterile × Marble Hall (ISI = 0.12; t2 = 4.98; p =0.01) and Sterile × Citrusdal (ISI = 0.13; t2 = 3.96; p = 0.01) populations. The male relative performance index was significant in both combinations, indicating that non-sterile laboratory males outcompeted the sterile males in these two combinations. When given no choice, evaluated as spermatophore transfer/ female/ 48h, all males (including sterile) were successful in transferring spermatophores to all FCM populations, with no significant differences. These results indicate that there may be incipient pre-isolation mechanisms affected by local natural selection, resulting in localised sexual attraction via differences in the sex pheromone ratios. These findings provide important information for semiochemical technologies and the implication of these results with regard to monitoring with sex pheromones, attract-and-kill, mating disruption and sterile insect technique are discussed.
- Full Text:
- Date Issued: 2020
Shoutfighting and other fiction
- Authors: Rasmenike, Nonqubela Evelyn
- Date: 2020
- Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/144500 , vital:38351
- Description: This document consists of three parts: Part A: English Half Thesis (Creative Work) ; Part B: IsiXhosa Half Thesis (Creative Work) ; Part C: Portfolio.
- Full Text:
- Date Issued: 2020
- Authors: Rasmenike, Nonqubela Evelyn
- Date: 2020
- Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century
- Language: English , Xhosa
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/144500 , vital:38351
- Description: This document consists of three parts: Part A: English Half Thesis (Creative Work) ; Part B: IsiXhosa Half Thesis (Creative Work) ; Part C: Portfolio.
- Full Text:
- Date Issued: 2020