Observing cosmic reionization with PAPER: polarized foreground simulations and all sky images
- Authors: Nunhokee, Chuneeta Devi
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Epoch of reionization -- Research , Hydrogen -- Spectra , Radio interferometers
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68203 , vital:29218
- Description: The Donald C. Backer Precision Array to Probe the Epoch of Reionization (PAPER, Parsons et al., 2010) was built with an aim to detect the redshifted 21 cm Hydrogen line, which is likely the best probe of thermal evolution of the intergalactic medium and reionization of neutral Hydrogen in our Universe. Observations of the 21 cm signal are challenged by bright astrophysical foregrounds and systematics that require precise modeling in order to extract the cosmological signal. In particular, the instrumental leakage of polarized foregrounds may contaminate the 21 cm power spectrum. In this work, we developed a formalism to describe the leakage due to instrumental widefield effects in visibility-based power spectra and used it to predict contaminations in observations. We find the leakage due to a population of point sources to be higher than the diffuse Galactic emission – for which we can predict minimal contaminations at k>0.3 h Mpc -¹ We also analyzed data from the last observing season of PAPER via all-sky imaging with a view to characterize the foregrounds. We generated an all-sky catalogue of 88 sources down to a flux density of 5 Jy. Moreover, we measured both polarized point source and the Galactic diffuse emission, and used these measurements to constrain our model of polarization leakage. We find the leakage due to a population of point sources to be 12% lower than the prediction from our polarized model.
- Full Text:
- Authors: Nunhokee, Chuneeta Devi
- Date: 2019
- Subjects: Cosmic background radiation , Astronomy -- Observations , Epoch of reionization -- Research , Hydrogen -- Spectra , Radio interferometers
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/68203 , vital:29218
- Description: The Donald C. Backer Precision Array to Probe the Epoch of Reionization (PAPER, Parsons et al., 2010) was built with an aim to detect the redshifted 21 cm Hydrogen line, which is likely the best probe of thermal evolution of the intergalactic medium and reionization of neutral Hydrogen in our Universe. Observations of the 21 cm signal are challenged by bright astrophysical foregrounds and systematics that require precise modeling in order to extract the cosmological signal. In particular, the instrumental leakage of polarized foregrounds may contaminate the 21 cm power spectrum. In this work, we developed a formalism to describe the leakage due to instrumental widefield effects in visibility-based power spectra and used it to predict contaminations in observations. We find the leakage due to a population of point sources to be higher than the diffuse Galactic emission – for which we can predict minimal contaminations at k>0.3 h Mpc -¹ We also analyzed data from the last observing season of PAPER via all-sky imaging with a view to characterize the foregrounds. We generated an all-sky catalogue of 88 sources down to a flux density of 5 Jy. Moreover, we measured both polarized point source and the Galactic diffuse emission, and used these measurements to constrain our model of polarization leakage. We find the leakage due to a population of point sources to be 12% lower than the prediction from our polarized model.
- Full Text:
Occurrence, feeding ecology, and population structure of two dolphin species, Tursiops aduncus and Delphinus delphis, off the Wild Coast of South Africa
- Authors: Caputo, Michelle Anne
- Date: 2019
- Subjects: Delphinus -- South Africa-- Kwazulu-Natal -- Ecology , Tursoops -- South Africa-- Kwazulu-Natal -- Ecology , Delphinus -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Tursoops -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Dolphins -- South Africa-- Kwazulu-Natal , Delphinus -- South Africa-- Kwazulu-Natal -- Behavior , Tursoops -- South Africa-- Kwazulu-Natal -- Behavior , Marine ecology -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115612 , vital:34197
- Description: Dolphins are apex predators and their movements, foraging activities and population dynamics play an important role in shaping their environment. Understanding their occurrence, movement patterns, and trophic ecology is essential to their conservation, especially as they are considered sentinel species. The Wild Coast of South Africa’s Eastern Cape, is characterized by the annual sardine (Sardinops sagax) run, which serves as an important foraging event for apex predators, including Indo-Pacific bottlenose (Tursiops aduncus) and long-beaked common dolphins (Delphinus delphis). Despite the ecological significance of this event, no dedicated surveys for these species have previously been conducted in this area. The main objectives of this research were to: investigate long-term occurrence of dolphins during the sardine run to determine if there have been any changes over the past 19 years, as has been predicted from common dolphin dietary investigations and anecdotal evidence; to determine short-term occurrence and movement patterns of selected inshore delphinids within the area, which is characterized by three marine protected areas (MPAs); and to use stable isotope analyses to determine trophic relationships and population structure of bottlenose and common dolphins within the region. Long-term data consisted of 131 opportunistic aerial surveys conducted between May and July over the period 1996 to 2014. Results from these surveys indicate that common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p=0.0343). Bottlenose dolphins, demonstrated no such trend (p=0.916). For both species, greater majority (> 70% of total counts) of sightings were made inside the MPAs. Short-term boat-based surveys were conducted three times a year between June 2014 and December 2016, contributing to a total of 47 days of surveys divided into three locations: Amathole, Hluleka, and Pondoland, each containing a MPA. Density and group size data were analyzed for both species and photographic identification analysis was performed for photographs of bottlenose dolphin dorsal fins. Results indicate that animal and sighting density did not differ temporally (bottlenose dolphin: sighting density – p=0.398, individual density –p=0.781; common dolphin: sighting density –p=0.472, individual density – p=0.204). Environmental factors (sea surface temperature, depth, substrate, and distance from shore) appeared to have limited effect on individual and sighting density and group size for both species (p>0.05). Photographic identification of bottlenose dolphins resulted in 2149 individuals, with a 11.8% resighting rate, with the highest resighting rate within the Pondoland MPA (16.1%). The resighting count did not differ temporally between monthly survey based on generalized linear models (p=0.866), but did differ between study areas (p<0.0001). These results provide the first evidence of the occurrence of both species of dolphin off the Wild Coast, as they were sighted in this region in all survey months. There was no trend in density based on temporal or environmental factors, which suggests other factors are influencing their occurrence. Resightings of bottlenose dolphins within the area suggest that there is some degree of residency, though the majority of animals were only sighted on a single occasion and there was no plateau in the discovery curve. A total of 256 biopsy samples (bottlenose dolphins =128; common dolphins=128) were collected during boat-based surveys. Bottlenose dolphin samples were also collected from adjacent areas to the southwest (Algoa Bay, n=22) and northeast (KwaZulu-Natal (KZN), n=20) of the Wild Coast to investigate similarities and differences between these areas. Despite a high degree of niche overlap between the two species (41%), common dolphins fed with a broader niche (standard ellipse area probability 0.89) than bottlenose dolphins in the summer and a narrower niche in the winter (probability 0.94). There was a clear spatial variation in the diet of bottlenose dolphins along the coast, with individuals from Algoa Bay and Amathole demonstrating 0% niche overlap with individuals from KZN, but the mechanism for these differences remains unclear as other species from South African waters demonstrate a strong southwest to northeast gradient in nitrogen for the Eastern Cape coastline. This research provides valuable baseline information regarding dolphins off the Wild Coast of South Africa, which remained largely unknown. My results indicate that bottlenose dolphins may be more resident in the Wild Coast than previous predicted, and confirm that common dolphins are highly mobile in this area.
- Full Text:
- Authors: Caputo, Michelle Anne
- Date: 2019
- Subjects: Delphinus -- South Africa-- Kwazulu-Natal -- Ecology , Tursoops -- South Africa-- Kwazulu-Natal -- Ecology , Delphinus -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Tursoops -- South Africa-- Kwazulu-Natal -- Feeding and feeds , Dolphins -- South Africa-- Kwazulu-Natal , Delphinus -- South Africa-- Kwazulu-Natal -- Behavior , Tursoops -- South Africa-- Kwazulu-Natal -- Behavior , Marine ecology -- South Africa -- Kwazulu-Natal
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115612 , vital:34197
- Description: Dolphins are apex predators and their movements, foraging activities and population dynamics play an important role in shaping their environment. Understanding their occurrence, movement patterns, and trophic ecology is essential to their conservation, especially as they are considered sentinel species. The Wild Coast of South Africa’s Eastern Cape, is characterized by the annual sardine (Sardinops sagax) run, which serves as an important foraging event for apex predators, including Indo-Pacific bottlenose (Tursiops aduncus) and long-beaked common dolphins (Delphinus delphis). Despite the ecological significance of this event, no dedicated surveys for these species have previously been conducted in this area. The main objectives of this research were to: investigate long-term occurrence of dolphins during the sardine run to determine if there have been any changes over the past 19 years, as has been predicted from common dolphin dietary investigations and anecdotal evidence; to determine short-term occurrence and movement patterns of selected inshore delphinids within the area, which is characterized by three marine protected areas (MPAs); and to use stable isotope analyses to determine trophic relationships and population structure of bottlenose and common dolphins within the region. Long-term data consisted of 131 opportunistic aerial surveys conducted between May and July over the period 1996 to 2014. Results from these surveys indicate that common dolphins, typically associated with sardines, decreased significantly in average group size over the study period (p=0.0343). Bottlenose dolphins, demonstrated no such trend (p=0.916). For both species, greater majority (> 70% of total counts) of sightings were made inside the MPAs. Short-term boat-based surveys were conducted three times a year between June 2014 and December 2016, contributing to a total of 47 days of surveys divided into three locations: Amathole, Hluleka, and Pondoland, each containing a MPA. Density and group size data were analyzed for both species and photographic identification analysis was performed for photographs of bottlenose dolphin dorsal fins. Results indicate that animal and sighting density did not differ temporally (bottlenose dolphin: sighting density – p=0.398, individual density –p=0.781; common dolphin: sighting density –p=0.472, individual density – p=0.204). Environmental factors (sea surface temperature, depth, substrate, and distance from shore) appeared to have limited effect on individual and sighting density and group size for both species (p>0.05). Photographic identification of bottlenose dolphins resulted in 2149 individuals, with a 11.8% resighting rate, with the highest resighting rate within the Pondoland MPA (16.1%). The resighting count did not differ temporally between monthly survey based on generalized linear models (p=0.866), but did differ between study areas (p<0.0001). These results provide the first evidence of the occurrence of both species of dolphin off the Wild Coast, as they were sighted in this region in all survey months. There was no trend in density based on temporal or environmental factors, which suggests other factors are influencing their occurrence. Resightings of bottlenose dolphins within the area suggest that there is some degree of residency, though the majority of animals were only sighted on a single occasion and there was no plateau in the discovery curve. A total of 256 biopsy samples (bottlenose dolphins =128; common dolphins=128) were collected during boat-based surveys. Bottlenose dolphin samples were also collected from adjacent areas to the southwest (Algoa Bay, n=22) and northeast (KwaZulu-Natal (KZN), n=20) of the Wild Coast to investigate similarities and differences between these areas. Despite a high degree of niche overlap between the two species (41%), common dolphins fed with a broader niche (standard ellipse area probability 0.89) than bottlenose dolphins in the summer and a narrower niche in the winter (probability 0.94). There was a clear spatial variation in the diet of bottlenose dolphins along the coast, with individuals from Algoa Bay and Amathole demonstrating 0% niche overlap with individuals from KZN, but the mechanism for these differences remains unclear as other species from South African waters demonstrate a strong southwest to northeast gradient in nitrogen for the Eastern Cape coastline. This research provides valuable baseline information regarding dolphins off the Wild Coast of South Africa, which remained largely unknown. My results indicate that bottlenose dolphins may be more resident in the Wild Coast than previous predicted, and confirm that common dolphins are highly mobile in this area.
- Full Text:
Perspectives on land and water politics at Mushandike Irrigation Scheme, Masvingo, Zimbabwe
- Authors: Mafukidze, Jonathan
- Date: 2019
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76479 , vital:30573
- Description: Access to, control and ownership of land and water, amongst other natural resources in Zimbabwe, shape and affect rural lives, livelihoods, social relations and social organisation. Rural poverty has been entrenched and exacerbated by, amongst other factors, highly restricted access to these scarce resources. Historically, Zimbabwe’s rural areas (such as communal areas, smallholder irrigation schemes and resettlement areas) have existed as sites of struggles where contestations and negotiations over access to, control or ownership of these resources have taken place. Resultantly, multifaceted and dynamic social relations have been weaved and contested social spaces carved out. In rural Zimbabwe, contestations have tended to be complex, nuanced and intricate, working themselves out in different ways across time and space. In their heightened and more visible state, they have been characterised by violent physical expressions which, in the history of the country, involved two wars of liberation, the First Chimurenga (1896-1897) and the Second Chimurenga (1960s to 1980). The most recent violent manifestation was through nation-wide land invasions, politically christened the Third Chimurenga, which peaked in 2000 and continued sporadically to this day. Few studies on smallholder irrigation schemes in Zimbabwe have focused on understanding how contestations for access to scarce land and water resources are framed and negotiated at the local level. Cognisant of this lacuna, this thesis uses social constructionism in examining, as a case study, Mushandike Smallholder Irrigation Scheme in Masvingo Province in order to understand and analyse how land and water politics occur at the local level. The study deploys a qualitative research methodology approach in examining local water and land politics, which involved original irrigation beneficiaries and more recent land invaders. Findings of the thesis indicate that land and water shortages have increased considerably in the past two decades at the irrigation scheme due to the influx of land invaders into the scheme. This influx has had a negative impact on agricultural production and other livelihood strategies. Both scheme members and land invaders lay claim to land and water at Mushandike. These claims are intricately constructed and contested, and they are linked to broader issues such as partisan party-politics, policy developments, and tradition, origin, indigeneity and belonging. Though the struggles over land and water at Mushandike are firmly rooted in the concrete conditions of existence and experiences of beneficiaries and land invaders, external actors such as political leaders, state bureaucrats and traditional chiefs tend to complicate and intensify the contestations.
- Full Text:
- Authors: Mafukidze, Jonathan
- Date: 2019
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76479 , vital:30573
- Description: Access to, control and ownership of land and water, amongst other natural resources in Zimbabwe, shape and affect rural lives, livelihoods, social relations and social organisation. Rural poverty has been entrenched and exacerbated by, amongst other factors, highly restricted access to these scarce resources. Historically, Zimbabwe’s rural areas (such as communal areas, smallholder irrigation schemes and resettlement areas) have existed as sites of struggles where contestations and negotiations over access to, control or ownership of these resources have taken place. Resultantly, multifaceted and dynamic social relations have been weaved and contested social spaces carved out. In rural Zimbabwe, contestations have tended to be complex, nuanced and intricate, working themselves out in different ways across time and space. In their heightened and more visible state, they have been characterised by violent physical expressions which, in the history of the country, involved two wars of liberation, the First Chimurenga (1896-1897) and the Second Chimurenga (1960s to 1980). The most recent violent manifestation was through nation-wide land invasions, politically christened the Third Chimurenga, which peaked in 2000 and continued sporadically to this day. Few studies on smallholder irrigation schemes in Zimbabwe have focused on understanding how contestations for access to scarce land and water resources are framed and negotiated at the local level. Cognisant of this lacuna, this thesis uses social constructionism in examining, as a case study, Mushandike Smallholder Irrigation Scheme in Masvingo Province in order to understand and analyse how land and water politics occur at the local level. The study deploys a qualitative research methodology approach in examining local water and land politics, which involved original irrigation beneficiaries and more recent land invaders. Findings of the thesis indicate that land and water shortages have increased considerably in the past two decades at the irrigation scheme due to the influx of land invaders into the scheme. This influx has had a negative impact on agricultural production and other livelihood strategies. Both scheme members and land invaders lay claim to land and water at Mushandike. These claims are intricately constructed and contested, and they are linked to broader issues such as partisan party-politics, policy developments, and tradition, origin, indigeneity and belonging. Though the struggles over land and water at Mushandike are firmly rooted in the concrete conditions of existence and experiences of beneficiaries and land invaders, external actors such as political leaders, state bureaucrats and traditional chiefs tend to complicate and intensify the contestations.
- Full Text:
Ph-responsive liposomal systems for site-specific pulmonary delivery of anti-tubercular drugs
- Nkanga, Christian Isalomboto
- Authors: Nkanga, Christian Isalomboto
- Date: 2019
- Subjects: Tuberculosis -- Chemotherapy , Lipsomes , Drug carriers (Pharmacy) , Rifampin , Hydrogen-ion concentration , Hydrogen-ion concentration -- Physiological effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/125832 , vital:35822
- Description: Tuberculosis (TB) is an infectious disease that has been reported to be the ninth leading cause of death worldwide, even though mostly considered as a poverty related disease. Despite the existence of potent anti-tubercular drugs (ATBDs), such as rifampicin (RIF) and isoniazid (INH), TB remains the major killer among many microbial diseases over the last five years. Although several factors are to be blamed for this deadly status, the most crucial issues encompass both the self-defensiveness of the causative agent (Mycobacterium tuberculosis), including its intra-macrophage location that compromises ATBDs accessibility, and the widespread/off target distribution of ATBDs. The need for novel drug delivery strategies therefore arises to provide selective distribution of ATBDs at the infected site. Among the drug vehicles explored in this field, liposomes have been reported to be the most suitable drug carriers due to their rapid uptake by alveolar macrophages, where M. tuberculosis often resides. Since liposomes experience media of different pH throughout the cell uptake process (endocytosis/phagocytosis), the use of pH change as a stimulus for controlled release looks promising for enhancing intra-macrophage delivery and minimizing premature ‘off-target’ release of ATBDs. However, the costly status of liposome technology, due to the use of sophisticated procedures and expensive materials (especially for pH-dependent delivery, where special lipids are required), may preclude wider developments of liposomal products, especially for the developing world. This study aimed at investigating liposomal encapsulation of pH-sensitive and fluorescent hydrazone derivatives of INH using crude soybean lecithin, as a cost-effective option for site-specific delivery combined with potential bio-imaging features. Another objective was to explore encapsulation of INH hydrazone derivatives with and without RIF in liposomes using a simple and organic solvent-free preparation method. Initially, INH was coupled with 4-hydroxy-benzaldehyde to yield a conjugate (INH-HB) that was encapsulated in liposomes using film hydration method with acceptable encapsulation efficiency (î), about 89 %. The prepared INH-HB loaded liposomes (IHL) were characterized by means of dynamic light scattering (DLS), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The release of INH from IHL was evaluated over 12 hours in media of different pH using dialysis. As hypothesized, pH dependent release of INH from IHL was observed with 22, 69, 83 and 100 % release obtained in media of pH 7.4, 6.4, 5.4 and 4.4, respectively. From this experimental trial, further development was undertaken by conjugating INH to a hydrophobic fluorescent tag, zinc (II) phthalocyanine (PC), through hydrazone linkages. The obtained conjugate (PC-INH) was loaded into liposomes (PIL) that were characterized using various spectroscopic techniques, including UV-Vis absorption and energy dispersive X-ray spectroscopy, which suggested the presence of PC-INH within the lipid bilayers. The release study performed in different pH media revealed 22, 41, 97 and 100 % of INH, respectively released at pH 7.4, 6.4, 5.4 and 4.4. This confirmed the potential of pH-triggered drug release from liposomes loaded with hydrazone drug derivatives. In addition, successful encapsulation of PC-INH using crude soybean lecithin inspired a new opening towards development of multimodal liposomes that could achieve controlled drug release with added benefits of image-guided biological tracking. However, the hydrophobic nature of PC-INH requires an effective strategy that could improve its solubility and favour extensive development. In this context, the tetra-substituted structure of PC-INH brought up the hypothesis that cyclodextrin (CD) complexation would facilitate PC-INH encapsulation in liposomes using an organic solvent-free method, called here the “heating method” (HM). Inclusion complexes of PC-INH with various CDs were therefore investigated, with gamma-CD complex (CP) giving the best results. These complexes were prepared in both solution and solid-state and further comprehensively characterized using UV-Vis spectroscopy, magnetic circular dichroism, NMR spectroscopy, diffusion ordered spectroscopy, DSC, XRD and Fourier transform infrared spectroscopy. CP-loaded liposomes prepared using HM exhibited greater î than film hydration liposomes, about 70 % versus 56 %, respectively. The HM-liposomal system (CPL) exhibited potentially useful nano particulate characteristics (i.e. mean particle size 240 nm and Zeta potential –57 mV), which remained unchanged over 5 weeks of stability study at 4 °C, and pH-dependent INH release behaviour alike PIL. Furthermore, CP was co-encapsulated with rifampicin (RIF) in liposomes using HM to investigate the possibility for future combination therapy. 1H-NMR spectroscopy, DSC, XRD and photophysical studies were performed for molecular assessment of the cargo in CP-RIF co-loaded liposomes (CPRL). The mean particle size, Zeta potential and î of CPRL were respectively 594 nm, –50 mV, 58 % for CP and 86 % for RIF. CPRL exhibited much higher release rates for both INH and RIF at pH 6.4, compared to those tested at pH 7.4. In addition, there was no cytotoxicity on HeLa cells, but attractive lung fibroblasts and epithelial cells uptake and viability. Hence, CPRL are promising for targeted ATBD delivery to alveolar macrophages following pulmonary administration. Overall, the developed pH-responsive liposomal system holds the promise for new openings towards wider developments of multifunctional liposomes for site-specific controlled pulmonary delivery of antimicrobials drugs.
- Full Text:
- Authors: Nkanga, Christian Isalomboto
- Date: 2019
- Subjects: Tuberculosis -- Chemotherapy , Lipsomes , Drug carriers (Pharmacy) , Rifampin , Hydrogen-ion concentration , Hydrogen-ion concentration -- Physiological effect
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/125832 , vital:35822
- Description: Tuberculosis (TB) is an infectious disease that has been reported to be the ninth leading cause of death worldwide, even though mostly considered as a poverty related disease. Despite the existence of potent anti-tubercular drugs (ATBDs), such as rifampicin (RIF) and isoniazid (INH), TB remains the major killer among many microbial diseases over the last five years. Although several factors are to be blamed for this deadly status, the most crucial issues encompass both the self-defensiveness of the causative agent (Mycobacterium tuberculosis), including its intra-macrophage location that compromises ATBDs accessibility, and the widespread/off target distribution of ATBDs. The need for novel drug delivery strategies therefore arises to provide selective distribution of ATBDs at the infected site. Among the drug vehicles explored in this field, liposomes have been reported to be the most suitable drug carriers due to their rapid uptake by alveolar macrophages, where M. tuberculosis often resides. Since liposomes experience media of different pH throughout the cell uptake process (endocytosis/phagocytosis), the use of pH change as a stimulus for controlled release looks promising for enhancing intra-macrophage delivery and minimizing premature ‘off-target’ release of ATBDs. However, the costly status of liposome technology, due to the use of sophisticated procedures and expensive materials (especially for pH-dependent delivery, where special lipids are required), may preclude wider developments of liposomal products, especially for the developing world. This study aimed at investigating liposomal encapsulation of pH-sensitive and fluorescent hydrazone derivatives of INH using crude soybean lecithin, as a cost-effective option for site-specific delivery combined with potential bio-imaging features. Another objective was to explore encapsulation of INH hydrazone derivatives with and without RIF in liposomes using a simple and organic solvent-free preparation method. Initially, INH was coupled with 4-hydroxy-benzaldehyde to yield a conjugate (INH-HB) that was encapsulated in liposomes using film hydration method with acceptable encapsulation efficiency (î), about 89 %. The prepared INH-HB loaded liposomes (IHL) were characterized by means of dynamic light scattering (DLS), transmission electron microscopy (TEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The release of INH from IHL was evaluated over 12 hours in media of different pH using dialysis. As hypothesized, pH dependent release of INH from IHL was observed with 22, 69, 83 and 100 % release obtained in media of pH 7.4, 6.4, 5.4 and 4.4, respectively. From this experimental trial, further development was undertaken by conjugating INH to a hydrophobic fluorescent tag, zinc (II) phthalocyanine (PC), through hydrazone linkages. The obtained conjugate (PC-INH) was loaded into liposomes (PIL) that were characterized using various spectroscopic techniques, including UV-Vis absorption and energy dispersive X-ray spectroscopy, which suggested the presence of PC-INH within the lipid bilayers. The release study performed in different pH media revealed 22, 41, 97 and 100 % of INH, respectively released at pH 7.4, 6.4, 5.4 and 4.4. This confirmed the potential of pH-triggered drug release from liposomes loaded with hydrazone drug derivatives. In addition, successful encapsulation of PC-INH using crude soybean lecithin inspired a new opening towards development of multimodal liposomes that could achieve controlled drug release with added benefits of image-guided biological tracking. However, the hydrophobic nature of PC-INH requires an effective strategy that could improve its solubility and favour extensive development. In this context, the tetra-substituted structure of PC-INH brought up the hypothesis that cyclodextrin (CD) complexation would facilitate PC-INH encapsulation in liposomes using an organic solvent-free method, called here the “heating method” (HM). Inclusion complexes of PC-INH with various CDs were therefore investigated, with gamma-CD complex (CP) giving the best results. These complexes were prepared in both solution and solid-state and further comprehensively characterized using UV-Vis spectroscopy, magnetic circular dichroism, NMR spectroscopy, diffusion ordered spectroscopy, DSC, XRD and Fourier transform infrared spectroscopy. CP-loaded liposomes prepared using HM exhibited greater î than film hydration liposomes, about 70 % versus 56 %, respectively. The HM-liposomal system (CPL) exhibited potentially useful nano particulate characteristics (i.e. mean particle size 240 nm and Zeta potential –57 mV), which remained unchanged over 5 weeks of stability study at 4 °C, and pH-dependent INH release behaviour alike PIL. Furthermore, CP was co-encapsulated with rifampicin (RIF) in liposomes using HM to investigate the possibility for future combination therapy. 1H-NMR spectroscopy, DSC, XRD and photophysical studies were performed for molecular assessment of the cargo in CP-RIF co-loaded liposomes (CPRL). The mean particle size, Zeta potential and î of CPRL were respectively 594 nm, –50 mV, 58 % for CP and 86 % for RIF. CPRL exhibited much higher release rates for both INH and RIF at pH 6.4, compared to those tested at pH 7.4. In addition, there was no cytotoxicity on HeLa cells, but attractive lung fibroblasts and epithelial cells uptake and viability. Hence, CPRL are promising for targeted ATBD delivery to alveolar macrophages following pulmonary administration. Overall, the developed pH-responsive liposomal system holds the promise for new openings towards wider developments of multifunctional liposomes for site-specific controlled pulmonary delivery of antimicrobials drugs.
- Full Text:
Photophysical properties and photodynamic therapy activities of symmetrical and asymmetrical porphyrins embedded into Pluronic polymer micelles and nonlinear optical properties of an asymmetrical phthalocyanine
- Authors: Managa, Muthumuni Elizabeth
- Date: 2019
- Subjects: Porphyrins , Phthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/67625 , vital:29122
- Description: This work reports on the synthesis of symmetrical and asymmetrical novel porphyrins that have been incorporated into Pluronic polymers, as well as the synthesis of asymmetrical phthalocyanine. The new compounds were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), mass spectrometry and UV–Visible spectroscopy. The porphyrins that are synthesised were not water soluble but upon incorporating into Pluronic polymer micelles, they became water soluble. The polymer was also modified and linked to folic acid, to enhance selectivity for photodynamic therapy application, where MCF7 breast cancer cells were used. The singlet oxygen quantum yields were lower for the metal free porphyrins as compared to metalled ones due to the heavy atom effect of ClGa, Zn and Cl2Si in the latter which encourages intersystem crossing to the triplet state. Singlet oxygen quantum yields for water soluble derivatives increased upon being encapsulated into the micelles for all. The Stern-Volmer constant (Ksv), binding constant (Kb) and number of binding sites (n) were investigated in order to understand the interaction between the polymer micelles and the porphyrins, and it was showed that the central metals play a role in the manner which the porphyrin interacts with the micelles. The dark toxicity and photodynamic activity of the novel porphyrins upon encapsulating to Pluronic polymer micelles is also reported. There was minimal dark toxicity for all complexes with > 90% cell survival. The photodynamic activity of water insoluble porphyrins improved when encapsulated into the micelles. Novel asymmetrical phthalocyanines were also synthesised for nonlinear optics (NLO) studies in solution and thin films.
- Full Text:
- Authors: Managa, Muthumuni Elizabeth
- Date: 2019
- Subjects: Porphyrins , Phthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/67625 , vital:29122
- Description: This work reports on the synthesis of symmetrical and asymmetrical novel porphyrins that have been incorporated into Pluronic polymers, as well as the synthesis of asymmetrical phthalocyanine. The new compounds were characterized by elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1H NMR), mass spectrometry and UV–Visible spectroscopy. The porphyrins that are synthesised were not water soluble but upon incorporating into Pluronic polymer micelles, they became water soluble. The polymer was also modified and linked to folic acid, to enhance selectivity for photodynamic therapy application, where MCF7 breast cancer cells were used. The singlet oxygen quantum yields were lower for the metal free porphyrins as compared to metalled ones due to the heavy atom effect of ClGa, Zn and Cl2Si in the latter which encourages intersystem crossing to the triplet state. Singlet oxygen quantum yields for water soluble derivatives increased upon being encapsulated into the micelles for all. The Stern-Volmer constant (Ksv), binding constant (Kb) and number of binding sites (n) were investigated in order to understand the interaction between the polymer micelles and the porphyrins, and it was showed that the central metals play a role in the manner which the porphyrin interacts with the micelles. The dark toxicity and photodynamic activity of the novel porphyrins upon encapsulating to Pluronic polymer micelles is also reported. There was minimal dark toxicity for all complexes with > 90% cell survival. The photodynamic activity of water insoluble porphyrins improved when encapsulated into the micelles. Novel asymmetrical phthalocyanines were also synthesised for nonlinear optics (NLO) studies in solution and thin films.
- Full Text:
Physicochemical properties and photodynamic therapy activities of indium and zinc phthalocyanine-nanoparticle conjugates
- Authors: Dube, Edith
- Date: 2019
- Subjects: Indium , Zinc , Phthalocyanines , Breast -- Cancer -- Photochemotherapy , Nanoparticles
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76506 , vital:30589
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position are reported. The Pcs contain either zinc or indium as central metals and have carboxyphenoxy, phenoxy propanoic acid, benzothiazole phenoxy, thiophine ethoxy or di-O-isopropylidene-α-D-glucopyranose as ring substituents. The Pcs were linked to NPs via an amide bond or through self-assembly. The photophysics and photochemistry of the Pcs were assessed when alone and with conjugates. All the studied Pcs showed good photophysicochemical behaviour with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yield. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy–atom effect obtained from the former. Asymmetrical Pcs displayed higher triplet and singlet oxygen quantum yields than their symmetrical counterparts. The triplet quantum yield, generally increased on linkage to nanoparticles (NPs) due to the heavy–atom effect of gold and silver in NPs. The conjugates to gold nanospheres yielded higher triplet and singlet quantum yields than their gold nanotriangles counterparts due to the higher loading by the former probably encouraged by their relatively small particle size. The in vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. All complexes displayed poor phototoxicity with >50Îll viability at concentrations≤ 160μg/mL, however the conjugates showed<50% cell viabilityatconcentrations≤ 160μg/mLprobably due to the enhanced singlet oxygen quantum yield. The findings from this work show the importance of linking photosensitises such as phthalocyanines to metal nanoparticles for the enhancement ofsinglet oxygen quantum yield and ultimately the photodynamic effect.
- Full Text:
- Authors: Dube, Edith
- Date: 2019
- Subjects: Indium , Zinc , Phthalocyanines , Breast -- Cancer -- Photochemotherapy , Nanoparticles
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76506 , vital:30589
- Description: The syntheses and characterization of symmetric and asymmetric Pcs functionalized at the peripheral position are reported. The Pcs contain either zinc or indium as central metals and have carboxyphenoxy, phenoxy propanoic acid, benzothiazole phenoxy, thiophine ethoxy or di-O-isopropylidene-α-D-glucopyranose as ring substituents. The Pcs were linked to NPs via an amide bond or through self-assembly. The photophysics and photochemistry of the Pcs were assessed when alone and with conjugates. All the studied Pcs showed good photophysicochemical behaviour with relatively high triplet and singlet oxygen quantum yields corresponding to their low fluorescence quantum yield. The Pcs with indium in their central cavity exhibited higher triplet and singlet oxygen quantum yields in comparison to their zinc counterparts due to the heavy–atom effect obtained from the former. Asymmetrical Pcs displayed higher triplet and singlet oxygen quantum yields than their symmetrical counterparts. The triplet quantum yield, generally increased on linkage to nanoparticles (NPs) due to the heavy–atom effect of gold and silver in NPs. The conjugates to gold nanospheres yielded higher triplet and singlet quantum yields than their gold nanotriangles counterparts due to the higher loading by the former probably encouraged by their relatively small particle size. The in vitro dark cytotoxicity and photodynamic therapy of selected Pc complexes and conjugates against MCF-7 cells was tested. All studied Pc complexes and conjugates showed minimum dark toxicity making them applicable for PDT. All complexes displayed poor phototoxicity with >50Îll viability at concentrations≤ 160μg/mL, however the conjugates showed<50% cell viabilityatconcentrations≤ 160μg/mLprobably due to the enhanced singlet oxygen quantum yield. The findings from this work show the importance of linking photosensitises such as phthalocyanines to metal nanoparticles for the enhancement ofsinglet oxygen quantum yield and ultimately the photodynamic effect.
- Full Text:
Plants, people, and place: complex, mutualistic, and co-evolving global patterns through time
- Authors: Van Wijk, Yvette Ethné
- Date: 2019
- Subjects: Ethnobotany -- South Africa -- Western Cape , Khoisan (African people) -- Ethnobotany , Human-plant relationships -- South Africa -- Western Cape , Plants -- Classification -- South Africa -- Western Cape , Plant remains (Archaeology) -- South Africa -- Western Cape , Ethnoscience -- South Africa -- Western Cape , Regression analysis
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76575 , vital:30609
- Description: My thesis studies and analyses the suite of distinctive plant taxa which persist in small patches of vegetation growing in close association with archaeological habitation sites in the southern Cape, South Africa. The unexpected correlation and overlap between botanical taxa collected at 75 site complexes, and ethnobotanical data collected in collaboration with modern Khoi-San communities in the same area, is explored and interrogated. Although sparse, reports of the same suite of taxa recovered from archaeological excavations in the Cape provinces provides depth of time to the study, linking the past to the present. The three-way correlation of a suite of plants closely associated with humans and habitation sites through time, allows for triangulation of the data in order to validate and cross verify the results using more than one frame of reference. Both the plants and the knowledge about their uses have persisted in spite of historical attrition, and alienation of land and language, suffered by the Khoi-San over the past 300 years. Drawing on a large body of primary and secondary data, and using an interdisciplinary, abductive and pragmatic mixed methods approach, a pattern can be traced throughout Africa and globally. Regression analysis strongly indicates that the most ubiquitous taxa were selected for a purpose and are not randomly present in association with humans. Botanical, anthropological, and archaeological studies seldom focus on the inter-connectedness of people and plants at the sites they inhabited. Very little research into modern vegetation in close association with the sites has been undertaken, and vegetation mapping has not captured the occurrence of these site-specific small vegetation patches recorded during my surveys. The topographically, geologically, and vegetatively complex and varied southern Cape, and greater Cape area, is extremely rich in archaeological sites and history. This study suggests that the value of site-specific plant taxa to humans throughout the aeons of pre-agricultural history, persists into the present. Due to tolerance of a broad range of climatic and environmental variables, there is value in the study of these ancient and neglected useful plants in the face of climate change. That this vegetation is so closely associated with archaeological sites of cultural and historic importance confers an urgency to recognising the existence and significance of the distinctive and possibly anthropogenic vegetation surrounding the sites.
- Full Text:
- Authors: Van Wijk, Yvette Ethné
- Date: 2019
- Subjects: Ethnobotany -- South Africa -- Western Cape , Khoisan (African people) -- Ethnobotany , Human-plant relationships -- South Africa -- Western Cape , Plants -- Classification -- South Africa -- Western Cape , Plant remains (Archaeology) -- South Africa -- Western Cape , Ethnoscience -- South Africa -- Western Cape , Regression analysis
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76575 , vital:30609
- Description: My thesis studies and analyses the suite of distinctive plant taxa which persist in small patches of vegetation growing in close association with archaeological habitation sites in the southern Cape, South Africa. The unexpected correlation and overlap between botanical taxa collected at 75 site complexes, and ethnobotanical data collected in collaboration with modern Khoi-San communities in the same area, is explored and interrogated. Although sparse, reports of the same suite of taxa recovered from archaeological excavations in the Cape provinces provides depth of time to the study, linking the past to the present. The three-way correlation of a suite of plants closely associated with humans and habitation sites through time, allows for triangulation of the data in order to validate and cross verify the results using more than one frame of reference. Both the plants and the knowledge about their uses have persisted in spite of historical attrition, and alienation of land and language, suffered by the Khoi-San over the past 300 years. Drawing on a large body of primary and secondary data, and using an interdisciplinary, abductive and pragmatic mixed methods approach, a pattern can be traced throughout Africa and globally. Regression analysis strongly indicates that the most ubiquitous taxa were selected for a purpose and are not randomly present in association with humans. Botanical, anthropological, and archaeological studies seldom focus on the inter-connectedness of people and plants at the sites they inhabited. Very little research into modern vegetation in close association with the sites has been undertaken, and vegetation mapping has not captured the occurrence of these site-specific small vegetation patches recorded during my surveys. The topographically, geologically, and vegetatively complex and varied southern Cape, and greater Cape area, is extremely rich in archaeological sites and history. This study suggests that the value of site-specific plant taxa to humans throughout the aeons of pre-agricultural history, persists into the present. Due to tolerance of a broad range of climatic and environmental variables, there is value in the study of these ancient and neglected useful plants in the face of climate change. That this vegetation is so closely associated with archaeological sites of cultural and historic importance confers an urgency to recognising the existence and significance of the distinctive and possibly anthropogenic vegetation surrounding the sites.
- Full Text:
Pyramidal deliberative democracy
- Authors: Danielsen, James
- Date: 2019
- Subjects: Democracy , Information technology -- Political aspects , Internet in public administration , Political participation -- Computer network resources , World politics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/74502 , vital:30309
- Description: This dissertation has two main objectives. First, to outline an ICT-facilitated model of democracy called ‘pyramidal democracy’ that reconciles deliberative democracy with mass engagement. Second, to suggest how this model of democracy might engender the democratisation of the global economy and thus the provision of a basic level of economic security for all global citizens. At the core of the model is the pyramidal deliberative network, a means of organising citizens into small online deliberative groups and linking these groups together by means of an iterative process of delegate-selection and group-formation. The pyramidal network enables citizens to aggregate their preferences in a deliberative manner, and then project social power by authorizing the delegates at the top-tier of the pyramidal network to communicate their social demands to elected officials or to other points of authority. The envisioned outcome is the democratisation of the public sphere by means of the proliferation of deliberative networks in the government, market, and civil society spheres. Transnational pyramidal networks may make it feasible to instantiate a new citizen-based schema of global governance and, thereby, facilitate the reform of the United Nations and enable a transition towards global peace, sustainability, and distributive justice. Distributive justice might be achieved by means of implementing the six components of a democratised economy: participatory budgeting, fee-and-dividend taxes, a basic income, monetary reform, workplace democracy, and the sharing economy. Taken together, these components might enable the universal provision of a social minimum – a universal basic income sufficient for basic security and real freedom. Taken to its logical conclusion, a democratised economy may also enable a transition towards a post-scarcity economic order characterised by a maximal stock of humanmade and natural capital that would not exceed the sustainable carrying capacity of the earth.
- Full Text:
- Authors: Danielsen, James
- Date: 2019
- Subjects: Democracy , Information technology -- Political aspects , Internet in public administration , Political participation -- Computer network resources , World politics
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/74502 , vital:30309
- Description: This dissertation has two main objectives. First, to outline an ICT-facilitated model of democracy called ‘pyramidal democracy’ that reconciles deliberative democracy with mass engagement. Second, to suggest how this model of democracy might engender the democratisation of the global economy and thus the provision of a basic level of economic security for all global citizens. At the core of the model is the pyramidal deliberative network, a means of organising citizens into small online deliberative groups and linking these groups together by means of an iterative process of delegate-selection and group-formation. The pyramidal network enables citizens to aggregate their preferences in a deliberative manner, and then project social power by authorizing the delegates at the top-tier of the pyramidal network to communicate their social demands to elected officials or to other points of authority. The envisioned outcome is the democratisation of the public sphere by means of the proliferation of deliberative networks in the government, market, and civil society spheres. Transnational pyramidal networks may make it feasible to instantiate a new citizen-based schema of global governance and, thereby, facilitate the reform of the United Nations and enable a transition towards global peace, sustainability, and distributive justice. Distributive justice might be achieved by means of implementing the six components of a democratised economy: participatory budgeting, fee-and-dividend taxes, a basic income, monetary reform, workplace democracy, and the sharing economy. Taken together, these components might enable the universal provision of a social minimum – a universal basic income sufficient for basic security and real freedom. Taken to its logical conclusion, a democratised economy may also enable a transition towards a post-scarcity economic order characterised by a maximal stock of humanmade and natural capital that would not exceed the sustainable carrying capacity of the earth.
- Full Text:
Reading to learn for secondary schooling: an interventionist action research study within a South African under-privileged setting
- Authors: Mataka, Tawanda Wallace
- Date: 2019
- Subjects: Rose, David, 1955-. Reading to learn , Reading (Secondary) , English language -- Study and teaching (Secondary) -- Foreign speakers -- South Africa , English language -- Study and teaching (Secondary) -- Foreign speakers -- South Africa -- Case studies , Literacy -- South Africa -- Makhanda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92191 , vital:30706
- Description: The study examined the contribution that Rose’s (2005) Reading to Learn (RtL) methodology made in development of advanced literacy abilities recommended in the schooling system. RtL was influenced by Bernstein’s theory of pedagogic discourse, Bruner, Vygotsky’s social learning theory and Halliday’s systemic functional linguistics theory. The study used the same cohort of learners during Grades 11 and 12 in a black township secondary school in Grahamstown, Eastern Cape, South Africa. RtL was birthed in Australia with the intention of accelerating literacy development of learners in disadvantaged communities. Based on its success in Australia, I implemented the methodology against a backdrop of continuously declining literacy standards in South African primary and secondary schools. Researchers on literacy acknowledge that socioeconomic and geosocial circumstances cannot be divorced from poor literacy performances in South African schools. Although these two factors play a role in regressing literacy, pedagogical approaches play a role. RtL was employed as an intervention strategy with learners whose literacy abilities were found lacking in comparison to curriculum demands. Despite the focus being on learners whose performance was below expected academic levels, the able learners were motivated to further their advanced abilities. The learners whose performance was previously compromised performed to par with their able counterparts. RtL provided all learners an opportunity to apply, with less difficulty, the language approved by the schooling system. The two research questions sought to illuminate the role RtL played in developing learners’ ability to read, so that they could converse with text and put into writing practice what they had read. In this regard, creative and transactional assignments were written, and performance assessed to evaluate the RtL intervention. Secondly, the research allowed me to get an insight through interviews with learners as to how they were positively or negatively influenced through RtL in learning English as a First Additional Language. The study was a longitudinal action research study which had a life span of 22 months. It was dominantly qualitative with a thin quantitative strand. Data to evaluate effectiveness was generated from learners’ written work and interviews. The learners’ work was analysed using an RtL assessment tool adopted from Rose (2018), for the purposes of uniformity and reliability. Findings from interviews highlighted various views regarding the positive impact of RtL. What emerged from the findings is a reflection of the positive impact RtL had on literacy development. Significantly, learners’ work improved across the board, true to Rose’s assertion that learners exposed to teaching using RtL principles experience accelerated literacy development. Based on these findings, RtL implemented in a township setting in South Africa yields results similar to those in Australia and other countries.
- Full Text:
- Authors: Mataka, Tawanda Wallace
- Date: 2019
- Subjects: Rose, David, 1955-. Reading to learn , Reading (Secondary) , English language -- Study and teaching (Secondary) -- Foreign speakers -- South Africa , English language -- Study and teaching (Secondary) -- Foreign speakers -- South Africa -- Case studies , Literacy -- South Africa -- Makhanda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92191 , vital:30706
- Description: The study examined the contribution that Rose’s (2005) Reading to Learn (RtL) methodology made in development of advanced literacy abilities recommended in the schooling system. RtL was influenced by Bernstein’s theory of pedagogic discourse, Bruner, Vygotsky’s social learning theory and Halliday’s systemic functional linguistics theory. The study used the same cohort of learners during Grades 11 and 12 in a black township secondary school in Grahamstown, Eastern Cape, South Africa. RtL was birthed in Australia with the intention of accelerating literacy development of learners in disadvantaged communities. Based on its success in Australia, I implemented the methodology against a backdrop of continuously declining literacy standards in South African primary and secondary schools. Researchers on literacy acknowledge that socioeconomic and geosocial circumstances cannot be divorced from poor literacy performances in South African schools. Although these two factors play a role in regressing literacy, pedagogical approaches play a role. RtL was employed as an intervention strategy with learners whose literacy abilities were found lacking in comparison to curriculum demands. Despite the focus being on learners whose performance was below expected academic levels, the able learners were motivated to further their advanced abilities. The learners whose performance was previously compromised performed to par with their able counterparts. RtL provided all learners an opportunity to apply, with less difficulty, the language approved by the schooling system. The two research questions sought to illuminate the role RtL played in developing learners’ ability to read, so that they could converse with text and put into writing practice what they had read. In this regard, creative and transactional assignments were written, and performance assessed to evaluate the RtL intervention. Secondly, the research allowed me to get an insight through interviews with learners as to how they were positively or negatively influenced through RtL in learning English as a First Additional Language. The study was a longitudinal action research study which had a life span of 22 months. It was dominantly qualitative with a thin quantitative strand. Data to evaluate effectiveness was generated from learners’ written work and interviews. The learners’ work was analysed using an RtL assessment tool adopted from Rose (2018), for the purposes of uniformity and reliability. Findings from interviews highlighted various views regarding the positive impact of RtL. What emerged from the findings is a reflection of the positive impact RtL had on literacy development. Significantly, learners’ work improved across the board, true to Rose’s assertion that learners exposed to teaching using RtL principles experience accelerated literacy development. Based on these findings, RtL implemented in a township setting in South Africa yields results similar to those in Australia and other countries.
- Full Text:
Regional thickening as game-changing: examining transnational activities of gender and women-focused civil society actors for region-building in Southern Africa
- Authors: Nedziwe, Cecilia Lwiindi
- Date: 2019
- Subjects: International relations , Southern Africa Development Community , Regionalism -- Africa, Southern , Africa, Southern -- Foreign relations -- 1994- , Women in development -- Africa, Southern , Women -- Social conditions -- Africa, Southern , Women -- Political activity -- Africa, Southern , Women in public life -- Africa, Southern , Civil society -- Africa, Southern
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/95420 , vital:31154
- Description: This thesis argues that norms, in general, have proliferated in a neo-liberalising context since the 1990s, in particular norms on gender, and how they have changed to indicate new agency and influence, amounts to game change. Despite growing transnational activities, regionalisation and the increasing interface between state and non-state regionalism in a transnational context since the advent of liberalisation and democratisation, analyses in regional International Relations (IR) studies, so far, largely maintain linear logic. The increasing non-state processes, and their connection to state processes in norm creation, norm adaptation, norm diffusion and implementation around broad questions of security including in the area of gender, amount to regional thickening. Regional thickening revealed in terms of increasing regionalisation, regionalism, and region-ness whose effect is game-changing challenges mainstream linear approaches in regional IR studies. Game-changing here, refers to, processes promoting the development of norms mentioned above in the interest of contributing to improved security across a region. This study is focused on Southern Africa, defined here, as the Southern African Development Community (SADC) region. This study’s analytical approach is informed by alternatives to mainstream approaches, emphasising processes, rather than linearity inherent in regional IR studies. By privileging the actual game-changing processes, interactions, and agency around the norm development cycle, this study examines how regional thickening in a transnational context promotes game-changing activities, promoting the development of the norm cycle, seeking to have improved security. A mixed method approach involving gathering of information from multiple primary and secondary sources are used. The study found transnational activities and regionalisation of gender and women-focused civil society actors, game-changing. These civil society actors organised in two ways. First, by way of advocacy and in seeking representation within intergovernmental policymaking structures at a regional level. Second, by way of organising around transnational communities in a transnational context in the interest of addressing gendered insecurities at localised levels. Regional thickening as game-changing here pointed to a growing recognition and participation of civil society actors in intergovernmental policymaking spaces as having created a groundswell for game change at localised levels. This led to policy development, adaptation, diffusion, and implementation by both state and non-state actors contributing to norm changes, improved social policies, and to greater security. The actual changes emerging from these actors’ activities on the ground are in terms of unlearning patriarchal behaviours, opening up development for women, and increasing their living standards, education, health, and their freedom. In assessing the transnational environment on gendered insecurity in Southern Africa, this thesis developed an innovative framework of regional thickening as game-changing. This framework plots how game-changing developed, evolved, and its importance in addressing gendered insecurity. The thesis has proposed that game-changing transnational activities and regionalisation that change, and diffuse norms to break learnt behaviour, have helped disrupt rigid institutionalisation, and are aiding to bring non-linear discourses to the fore.
- Full Text:
- Authors: Nedziwe, Cecilia Lwiindi
- Date: 2019
- Subjects: International relations , Southern Africa Development Community , Regionalism -- Africa, Southern , Africa, Southern -- Foreign relations -- 1994- , Women in development -- Africa, Southern , Women -- Social conditions -- Africa, Southern , Women -- Political activity -- Africa, Southern , Women in public life -- Africa, Southern , Civil society -- Africa, Southern
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/95420 , vital:31154
- Description: This thesis argues that norms, in general, have proliferated in a neo-liberalising context since the 1990s, in particular norms on gender, and how they have changed to indicate new agency and influence, amounts to game change. Despite growing transnational activities, regionalisation and the increasing interface between state and non-state regionalism in a transnational context since the advent of liberalisation and democratisation, analyses in regional International Relations (IR) studies, so far, largely maintain linear logic. The increasing non-state processes, and their connection to state processes in norm creation, norm adaptation, norm diffusion and implementation around broad questions of security including in the area of gender, amount to regional thickening. Regional thickening revealed in terms of increasing regionalisation, regionalism, and region-ness whose effect is game-changing challenges mainstream linear approaches in regional IR studies. Game-changing here, refers to, processes promoting the development of norms mentioned above in the interest of contributing to improved security across a region. This study is focused on Southern Africa, defined here, as the Southern African Development Community (SADC) region. This study’s analytical approach is informed by alternatives to mainstream approaches, emphasising processes, rather than linearity inherent in regional IR studies. By privileging the actual game-changing processes, interactions, and agency around the norm development cycle, this study examines how regional thickening in a transnational context promotes game-changing activities, promoting the development of the norm cycle, seeking to have improved security. A mixed method approach involving gathering of information from multiple primary and secondary sources are used. The study found transnational activities and regionalisation of gender and women-focused civil society actors, game-changing. These civil society actors organised in two ways. First, by way of advocacy and in seeking representation within intergovernmental policymaking structures at a regional level. Second, by way of organising around transnational communities in a transnational context in the interest of addressing gendered insecurities at localised levels. Regional thickening as game-changing here pointed to a growing recognition and participation of civil society actors in intergovernmental policymaking spaces as having created a groundswell for game change at localised levels. This led to policy development, adaptation, diffusion, and implementation by both state and non-state actors contributing to norm changes, improved social policies, and to greater security. The actual changes emerging from these actors’ activities on the ground are in terms of unlearning patriarchal behaviours, opening up development for women, and increasing their living standards, education, health, and their freedom. In assessing the transnational environment on gendered insecurity in Southern Africa, this thesis developed an innovative framework of regional thickening as game-changing. This framework plots how game-changing developed, evolved, and its importance in addressing gendered insecurity. The thesis has proposed that game-changing transnational activities and regionalisation that change, and diffuse norms to break learnt behaviour, have helped disrupt rigid institutionalisation, and are aiding to bring non-linear discourses to the fore.
- Full Text:
Responding to iconic images of risk through reflexive and narrative enquiry represented in a stratified text for environmental education readers
- Authors: Murphy, Mary
- Date: 2019
- Subjects: Sustainability -- Study and teaching , Environmental education -- Philosophy , Environmental degradation -- Study and teaching , Environmental degradation -- Philosophy , Reflection (Philosophy) , Archer, Margaret S (Margaret Scotford). Structure, agency, and the internal conversation
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/96768 , vital:31318
- Description: This thesis presents a stratified textual strategy to represent meaning developed through reflexive and narrative enquiry of environmental risk. Meaning that emerged in responses to iconic images of risk. Umberto Eco cautioned that iconic images over time become conventional taking over from that which they represent. Representations of risk become embedded through cultural coding. Semiotic theory provided access to the contextual and cultural content of environmental education as experienced during professional work as a radio presenter of “Environmental Matters”, as an environmental educator and activist. Methodological rigour was applied through the application of Margaret Archer's theory of the internal conversation and use of an online content management system. Both the reflexive tool of the internal conversation and the textual mechanism of the blog encouraged commitment to Paul Hart's criteria of trustworthiness and authenticity in the process of building the semiotic structure of the PhD. The Internal Conversation was used as a mediating tool in the PhD process and is presented in practice. Rethinking environmental risk from other species' perspectives through imagined experience was achieved through narrative enquiry. A noted anthropocentric limitation of the inability to interview animals for their experience of human-imposed risk was mitigated through representing the imagined, possible perspectives through story, which invites the reader to join the meaning-making process and open up discussions for and about environmental issues and action. This noted anthropocentrism was evident in debates among the characters about violence and non-violence as a conditioned theme and topic discussed in previous academic research about terrorism in divided societies. The story illustrates how the main character, a penguin called Polo, navigates through emerging meaning within a structure that confronts him with choices that end with a decision to become an agent for change. This story is a narrative example of the morphogenetic process. The multi-textual strategy presents possible methods for the exploration of risk (Vol. 1), reflexivity (Vol. 2) and representation (Vol. 3) for the application and contribution in/to environmental education.
- Full Text:
- Authors: Murphy, Mary
- Date: 2019
- Subjects: Sustainability -- Study and teaching , Environmental education -- Philosophy , Environmental degradation -- Study and teaching , Environmental degradation -- Philosophy , Reflection (Philosophy) , Archer, Margaret S (Margaret Scotford). Structure, agency, and the internal conversation
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/96768 , vital:31318
- Description: This thesis presents a stratified textual strategy to represent meaning developed through reflexive and narrative enquiry of environmental risk. Meaning that emerged in responses to iconic images of risk. Umberto Eco cautioned that iconic images over time become conventional taking over from that which they represent. Representations of risk become embedded through cultural coding. Semiotic theory provided access to the contextual and cultural content of environmental education as experienced during professional work as a radio presenter of “Environmental Matters”, as an environmental educator and activist. Methodological rigour was applied through the application of Margaret Archer's theory of the internal conversation and use of an online content management system. Both the reflexive tool of the internal conversation and the textual mechanism of the blog encouraged commitment to Paul Hart's criteria of trustworthiness and authenticity in the process of building the semiotic structure of the PhD. The Internal Conversation was used as a mediating tool in the PhD process and is presented in practice. Rethinking environmental risk from other species' perspectives through imagined experience was achieved through narrative enquiry. A noted anthropocentric limitation of the inability to interview animals for their experience of human-imposed risk was mitigated through representing the imagined, possible perspectives through story, which invites the reader to join the meaning-making process and open up discussions for and about environmental issues and action. This noted anthropocentrism was evident in debates among the characters about violence and non-violence as a conditioned theme and topic discussed in previous academic research about terrorism in divided societies. The story illustrates how the main character, a penguin called Polo, navigates through emerging meaning within a structure that confronts him with choices that end with a decision to become an agent for change. This story is a narrative example of the morphogenetic process. The multi-textual strategy presents possible methods for the exploration of risk (Vol. 1), reflexivity (Vol. 2) and representation (Vol. 3) for the application and contribution in/to environmental education.
- Full Text:
Rural food security in Mutare District, Zimbabwe, 1947-2010
- Authors: Kusena, Bernard
- Date: 2019
- Subjects: Mutare (Zimbabwe) -- History , Zimbabwe -- History , Food security -- Zimbabwe , Poverty -- Zimbabwe , Rural pooer -- Zimbabwe , Crop losses -- Zimbabwe , Food relief -- Zimbabwe
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92865 , vital:30757
- Description: By taking Mutare District as its lens to explore the dynamics of rural food security in Zimbabwe, this thesis assesses the role of the state in tackling hunger among its rural populations. It examines the impact of colonial and post-colonial food policy on efforts to combat food insecurity. The thesis explores the uneasy options pursued by rural communities in response to droughts and other threats of hunger. It identifies and ranks crop failure as the chief culprit to the district’s efforts towards food security. The thesis illustrates the contestations between the state and its rural people over which sustainable approaches to adopt in order to end hunger and how such debates continually shaped policy. It grapples with questions about the various understandings of food security advanced by scholars within the rural African context. It demonstrates, for instance, that the post-colonial state inherited an erstwhile crop production structure which shunned food crops in favour of cash crops. There was obvious bias against local preferences for a robust, home-grown food regime which did not put rural livelihoods at risk of starvation. The thesis also argues that food can be used as an instrument of war as evidenced during the liberation struggle when the vast majority of people residing in rural areas, particularly women and children, were pushed to the edges of survival. In addition, the thesis demonstrates that the infamous Marange diamonds turned out to be a curse rather than a blessing due to the state’s lack of transparency in the beneficiation chain. It concludes by a detailed examination of the political economy of food aid, demonstrating why donors have not succeeded for long to combat hunger in the district. In light of this background, the thesis provides a more nuanced analysis of the whole question of rural food security using archival material, newspapers, government and civil society reports, interviews and field observation. The thesis benefits from the use of a multi-pronged theoretical framework to capture the disparate themes that form the bedrock of this study.
- Full Text:
- Authors: Kusena, Bernard
- Date: 2019
- Subjects: Mutare (Zimbabwe) -- History , Zimbabwe -- History , Food security -- Zimbabwe , Poverty -- Zimbabwe , Rural pooer -- Zimbabwe , Crop losses -- Zimbabwe , Food relief -- Zimbabwe
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92865 , vital:30757
- Description: By taking Mutare District as its lens to explore the dynamics of rural food security in Zimbabwe, this thesis assesses the role of the state in tackling hunger among its rural populations. It examines the impact of colonial and post-colonial food policy on efforts to combat food insecurity. The thesis explores the uneasy options pursued by rural communities in response to droughts and other threats of hunger. It identifies and ranks crop failure as the chief culprit to the district’s efforts towards food security. The thesis illustrates the contestations between the state and its rural people over which sustainable approaches to adopt in order to end hunger and how such debates continually shaped policy. It grapples with questions about the various understandings of food security advanced by scholars within the rural African context. It demonstrates, for instance, that the post-colonial state inherited an erstwhile crop production structure which shunned food crops in favour of cash crops. There was obvious bias against local preferences for a robust, home-grown food regime which did not put rural livelihoods at risk of starvation. The thesis also argues that food can be used as an instrument of war as evidenced during the liberation struggle when the vast majority of people residing in rural areas, particularly women and children, were pushed to the edges of survival. In addition, the thesis demonstrates that the infamous Marange diamonds turned out to be a curse rather than a blessing due to the state’s lack of transparency in the beneficiation chain. It concludes by a detailed examination of the political economy of food aid, demonstrating why donors have not succeeded for long to combat hunger in the district. In light of this background, the thesis provides a more nuanced analysis of the whole question of rural food security using archival material, newspapers, government and civil society reports, interviews and field observation. The thesis benefits from the use of a multi-pronged theoretical framework to capture the disparate themes that form the bedrock of this study.
- Full Text:
Shifting contexts, shifting identities: a realist exploration of transnational mobility, change and identity construction in South African Higher Education expatriates in Abu Dhabi, UAE.
- Authors: Reid, Gillian Janet
- Date: 2019
- Subjects: College teacher mobility , College teacher mobility -- Abū Ẓaby (United Arab Emirates) , College teachers, Foreign -- Abū Ẓaby (United Arab Emirates) , College teachers -- Psychology , Expatriation -- Psychological aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92898 , vital:30760
- Description: Positioned in relation to the globalization of higher education, this realist study is approached from an interest in identity and focuses on nine South African academics professional contexts in South Africa and Abu Dhabi, UAE. As the context of identity formation and emergence is always local, the intention of this research was never to generalize. Rather, in using Bhaskar’s critical realism as its underpinning philosophy, and Archer’s social realism, theories on self, personal and the development and attainment of social identity - her concept of analytical dualism and her morphogenetic framework, this qualitative case study was designed to explore how global and national powers and mechanism effected change in this sub-group of academic’s respective higher education sectors and institutions in post- 1994 South Africa and in Abu Dhabi between 2008 and 2016. The study suggests that participants perceived their academic roles and role-incumbent professional identities to have been negatively impacted by the changes that were implemented in the South African higher education sector as a result the countries reintroduction to the global stage. Their response to become transnational educators in Abu Dhabi’s presented them with conditions that allied their professional experiences of the transformation of South African’s higher education sector. This led to a continued sense of loss of academic agency and powerlessness. This effecting the emergence, through the personal power of reflectivity, combined with discourse and affinity powers and mechanisms, in a social identity that supplanted their academic identities.
- Full Text:
- Authors: Reid, Gillian Janet
- Date: 2019
- Subjects: College teacher mobility , College teacher mobility -- Abū Ẓaby (United Arab Emirates) , College teachers, Foreign -- Abū Ẓaby (United Arab Emirates) , College teachers -- Psychology , Expatriation -- Psychological aspects
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/92898 , vital:30760
- Description: Positioned in relation to the globalization of higher education, this realist study is approached from an interest in identity and focuses on nine South African academics professional contexts in South Africa and Abu Dhabi, UAE. As the context of identity formation and emergence is always local, the intention of this research was never to generalize. Rather, in using Bhaskar’s critical realism as its underpinning philosophy, and Archer’s social realism, theories on self, personal and the development and attainment of social identity - her concept of analytical dualism and her morphogenetic framework, this qualitative case study was designed to explore how global and national powers and mechanism effected change in this sub-group of academic’s respective higher education sectors and institutions in post- 1994 South Africa and in Abu Dhabi between 2008 and 2016. The study suggests that participants perceived their academic roles and role-incumbent professional identities to have been negatively impacted by the changes that were implemented in the South African higher education sector as a result the countries reintroduction to the global stage. Their response to become transnational educators in Abu Dhabi’s presented them with conditions that allied their professional experiences of the transformation of South African’s higher education sector. This led to a continued sense of loss of academic agency and powerlessness. This effecting the emergence, through the personal power of reflectivity, combined with discourse and affinity powers and mechanisms, in a social identity that supplanted their academic identities.
- Full Text:
Stakeholder relationship management of a Chinese Mining Organisation in Zimbabwe
- Authors: Chodokufa, Kudakwashe
- Date: 2019
- Subjects: Industrial management -- Zimbabwe , Mineral industries -- Zimbabwe -- Management , Investments, Chinese -- Zimbabwe
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115127 , vital:34080
- Description: Media reports and research has pointed out problems in the way that Chinese mining organisations in Zimbabwe are managing stakeholder relationships. The problems ranging from disgruntled communities and allegations of labour violations. Taking into account the impact that China’s FDI has had on the ailing Zimbabwean economy research into the management of stakeholder relationships becomes imperative to understand how Chinese mining organisations build and manage stakeholder relationships. A review of stakeholder theory has revealed that there is not much emphasis by researchers on how organisations manage their stakeholder relationships, but rather on the identification and analysis of stakeholders. Research that has focused on stakeholder relationships has focused on different elements found in stakeholder relationship management and not necessarily on how stakeholder relationships should be managed. On the other hand, stakeholder theory does not seem to include social licence to operate which is important in stakeholder relationship management within the mining context. The purpose of this study is to develop a multidimensional stakeholder relationship management process for the Chinese mining organisation in Zimbabwe, showing dynamic interactions between multiple stakeholder networks with complementary, competitive and/or cooperative interests, while taking into account the possibility that interests may vary according to the underlying context. Thirteen semi-structured in-depth interviews were conducted with three stakeholder groups of a Chinese mining organisation as identified from the literature, namely employees, government and the community. The critical incident technique (CIT) was adopted in developing the interview questions and facilitated the data collection process. Participants described 36 critical incidents. According to multiple stakeholders, the findings suggest that, the Chinese managers built the relationship with multiple stakeholders through friendship, negotiation, pretend not to understand, referral, singing a contract, started with problems, they just arrived and through the government. With the same relationship being managed by the Chinese managers by being hard, rough and ruthless, authoritative, Chinese way of doing things, used avoidance, lack of competency, through a third party and resolving conflict when managing stakeholder relationships. Showing that the building and managing of stakeholder relationships is socially constructed and experienced differently by stakeholders. The positive and negative relationship characteristics influenced how stakeholder relationships are managed by the selected Chinese mining organisation. In the presence of positive relationship characteristics which included, friendship,there was flexibility, power dynamics, accountability depends on situations, commitment a show of investment, do cooperate to a certain extent, trust began with an open mind, shared values: hardwork and profit, shared values: culture was associated with the Chinese managing the relationship through being kind, supportive, motivating and understanding; complaint; through a third party; controlling; Chinese way of doing things; and performance and reward management of stakeholder relationships. Whilst negative relationship characteristics which included fear, their hearts were hardened, Chinese had power, intimidaton, not accountable, lack of commitment, communication understanding, connotations and intretations, communication done through a third party; no cooperation want to cut coners; trust are they conveying what is being said; deception and misrepresentation; trust depends on experience; being told lies and not transparent were associated with negative (being authoritative; hard, rough and ruthless; avoidance; blame shifting and pushy) stakeholder relationship management by the Chinese managers. Hence, a proposition that negative or positive relationship characteristics result in negative or positive stakeholder relationship management by the Chinese managers was propossed. The following challenges were experienced in the management of stakeholder relationships namely, communication, corruption, cheating, political environment, working conditions and broken promises. The dynamic multidimensional stakeholder relationship management process was subsequently revised to accommodate the new relationship characteristics and their positive and negative influence on how stakeholder relationships are managed. The main contribution of this study is the dynamic multidimensional stakeholder relationship management process which was developed within the context of a Chinese mining organisation in Africa. It is recommended that practitioners utilise the dynamic multidimensional stakeholder relationship management process to assist them in understanding and conducting research on stakeholder relationships. Further research is suggested on developing the research proposition made in the study and to empirically test the dynamic multidimension stakeholder relationship management process in other industries that posses different or similar contexts as this study.
- Full Text:
- Authors: Chodokufa, Kudakwashe
- Date: 2019
- Subjects: Industrial management -- Zimbabwe , Mineral industries -- Zimbabwe -- Management , Investments, Chinese -- Zimbabwe
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115127 , vital:34080
- Description: Media reports and research has pointed out problems in the way that Chinese mining organisations in Zimbabwe are managing stakeholder relationships. The problems ranging from disgruntled communities and allegations of labour violations. Taking into account the impact that China’s FDI has had on the ailing Zimbabwean economy research into the management of stakeholder relationships becomes imperative to understand how Chinese mining organisations build and manage stakeholder relationships. A review of stakeholder theory has revealed that there is not much emphasis by researchers on how organisations manage their stakeholder relationships, but rather on the identification and analysis of stakeholders. Research that has focused on stakeholder relationships has focused on different elements found in stakeholder relationship management and not necessarily on how stakeholder relationships should be managed. On the other hand, stakeholder theory does not seem to include social licence to operate which is important in stakeholder relationship management within the mining context. The purpose of this study is to develop a multidimensional stakeholder relationship management process for the Chinese mining organisation in Zimbabwe, showing dynamic interactions between multiple stakeholder networks with complementary, competitive and/or cooperative interests, while taking into account the possibility that interests may vary according to the underlying context. Thirteen semi-structured in-depth interviews were conducted with three stakeholder groups of a Chinese mining organisation as identified from the literature, namely employees, government and the community. The critical incident technique (CIT) was adopted in developing the interview questions and facilitated the data collection process. Participants described 36 critical incidents. According to multiple stakeholders, the findings suggest that, the Chinese managers built the relationship with multiple stakeholders through friendship, negotiation, pretend not to understand, referral, singing a contract, started with problems, they just arrived and through the government. With the same relationship being managed by the Chinese managers by being hard, rough and ruthless, authoritative, Chinese way of doing things, used avoidance, lack of competency, through a third party and resolving conflict when managing stakeholder relationships. Showing that the building and managing of stakeholder relationships is socially constructed and experienced differently by stakeholders. The positive and negative relationship characteristics influenced how stakeholder relationships are managed by the selected Chinese mining organisation. In the presence of positive relationship characteristics which included, friendship,there was flexibility, power dynamics, accountability depends on situations, commitment a show of investment, do cooperate to a certain extent, trust began with an open mind, shared values: hardwork and profit, shared values: culture was associated with the Chinese managing the relationship through being kind, supportive, motivating and understanding; complaint; through a third party; controlling; Chinese way of doing things; and performance and reward management of stakeholder relationships. Whilst negative relationship characteristics which included fear, their hearts were hardened, Chinese had power, intimidaton, not accountable, lack of commitment, communication understanding, connotations and intretations, communication done through a third party; no cooperation want to cut coners; trust are they conveying what is being said; deception and misrepresentation; trust depends on experience; being told lies and not transparent were associated with negative (being authoritative; hard, rough and ruthless; avoidance; blame shifting and pushy) stakeholder relationship management by the Chinese managers. Hence, a proposition that negative or positive relationship characteristics result in negative or positive stakeholder relationship management by the Chinese managers was propossed. The following challenges were experienced in the management of stakeholder relationships namely, communication, corruption, cheating, political environment, working conditions and broken promises. The dynamic multidimensional stakeholder relationship management process was subsequently revised to accommodate the new relationship characteristics and their positive and negative influence on how stakeholder relationships are managed. The main contribution of this study is the dynamic multidimensional stakeholder relationship management process which was developed within the context of a Chinese mining organisation in Africa. It is recommended that practitioners utilise the dynamic multidimensional stakeholder relationship management process to assist them in understanding and conducting research on stakeholder relationships. Further research is suggested on developing the research proposition made in the study and to empirically test the dynamic multidimension stakeholder relationship management process in other industries that posses different or similar contexts as this study.
- Full Text:
Statistical Analysis of the Radio-Interferometric Measurement Equation, a derived adaptive weighting scheme, and applications to LOFAR-VLBI observation of the Extended Groth Strip
- Authors: Bonnassieux, Etienne
- Date: 2019
- Subjects: Radio astronomy , Astrophysics , Astrophysics -- Instruments -- Calibration , Imaging systems in astronomy , Radio interferometers , Radio telescopes , Astronomy -- Observations
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93789 , vital:30942
- Description: J.R.R Tolkien wrote, in his Mythopoeia, that “He sees no stars who does not see them first, of living silver made that sudden burst, to flame like flowers beneath the ancient song”. In his defense of myth-making, he formulates the argument that the attribution of meaning is an act of creation - that “trees are not ‘trees’ until so named and seen” - and that this capacity for creation defines the human creature. The scientific endeavour, in this context, can be understood as a social expression of a fundamental feature of humanity, and from this endeavour flows much understanding. This thesis, one thread among many, focuses on the study of astronomical objects as seen by the radio waves they emit. What are radio waves? Electromagnetic waves were theorised by James Clerk Maxwell (Maxwell 1864) in his great theoretical contribution to modern physics, their speed matching the speed of light as measured by Ole Christensen R0mer and, later, James Bradley. It was not until Heinrich Rudolf Hertz’s 1887 experiment that these waves were measured in a laboratory, leading to the dawn of radio communications - and, later, radio astronomy. The link between radio waves and light was one of association: light is known to behave as a wave (Young double-slit experiment), with the same propagation speed as electromagnetic radiation. Light “proper” is also known to exist beyond the optical regime: Herschel’s experiment shows that when diffracted through a prism, sunlight warms even those parts of a desk which are not observed to be lit (first evidence of infrared light). The link between optical light and unseen electromagnetic radiation is then an easy step to make, and one confirmed through countless technological applications (e.g. optical fiber to name but one). And as soon as this link is established, a question immediately comes to the mind of the astronomer: what does the sky, our Universe, look like to the radio “eye”? Radio astronomy has a short but storied history: from Karl Jansky’s serendipitous observation of the centre of the Milky Way, which outshines our Sun in the radio regime, in 1933, to Grote Reber’s hand-built back-yard radio antenna in 1937, which successfully detected radio emission from the Milky Way itself, to such monumental projects as the Square Kilometer Array and its multiple pathfinders, it has led to countless discoveries and the opening of a truly new window on the Universe. The work presented in this thesis is a contribution to this discipline - the culmination of three years of study, which is a rather short time to get a firm grasp of radio interferometry both in theory and in practice. The need for robust, automated methods - which are improving daily, thanks to the tireless labour of the scientists in the field - is becoming ever stronger as the SKA approaches, looming large on the horizon; but even today, in the precursor era of LOFAR, MeerKAT and other pathfinders, it is keenly felt. When I started my doctorate, the sheer scale of the task at hand felt overwhelming - to actually be able to contribute to its resolution seemed daunting indeed! Thankfully, as the saying goes, no society sets for itself material goals which it cannot achieve. This thesis took place at an exciting time for radio interferometry: at the start of my doctorate, the LOFAR international stations were - to my knowledge - only beginning to be used, and even then, only tentatively; MeerKAT had not yet shown its first light; the techniques used throughout my work were still being developed. At the time of writing, great strides have been made. One of the greatest technical challenges of LOFAR - imaging using the international stations - is starting to become reality. This technical challenge is the key problem that this thesis set out to address. While we only achieved partial success so far, it is a testament to the difficulty of the task that it is not yet truly resolved. One of the major results of this thesis is a model of a bright resolved source near a famous extragalactic field: properly modeling this source not only allows the use of international LOFAR stations, but also grants deeper access to the extragalactic field itself, which is otherwise polluted by the 3C source’s sidelobes. This result was only achieved thanks to the other major result of this thesis: the development of a theoretical framework with which to better understand the effect of calibration errors on images made from interferometric data, and an algorithm to strongly mitigate them. The structure of this manuscript is as follows: we begin with an introduction to radio interferometry, LOFAR, and the emission mechanisms which dominate for our field of interest. These introductions are primarily intended to give a brief overview of the technical aspects of the data reduced in this thesis. We follow with an overview of the Measurement Equation formalism, which underpins our theoretical work. This is the keystone of this thesis. We then show the theoretical work that was developed as part of the research work done during the doctorate - which was published in Astronomy & Astrophysics. Its practical application - a quality-based weighting scheme - is used throughout our data reduction. This data reduction is the next topic of this thesis: we contextualise the scientific interest of the data we reduce, and explain both the methods and the results we achieve.
- Full Text:
- Authors: Bonnassieux, Etienne
- Date: 2019
- Subjects: Radio astronomy , Astrophysics , Astrophysics -- Instruments -- Calibration , Imaging systems in astronomy , Radio interferometers , Radio telescopes , Astronomy -- Observations
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93789 , vital:30942
- Description: J.R.R Tolkien wrote, in his Mythopoeia, that “He sees no stars who does not see them first, of living silver made that sudden burst, to flame like flowers beneath the ancient song”. In his defense of myth-making, he formulates the argument that the attribution of meaning is an act of creation - that “trees are not ‘trees’ until so named and seen” - and that this capacity for creation defines the human creature. The scientific endeavour, in this context, can be understood as a social expression of a fundamental feature of humanity, and from this endeavour flows much understanding. This thesis, one thread among many, focuses on the study of astronomical objects as seen by the radio waves they emit. What are radio waves? Electromagnetic waves were theorised by James Clerk Maxwell (Maxwell 1864) in his great theoretical contribution to modern physics, their speed matching the speed of light as measured by Ole Christensen R0mer and, later, James Bradley. It was not until Heinrich Rudolf Hertz’s 1887 experiment that these waves were measured in a laboratory, leading to the dawn of radio communications - and, later, radio astronomy. The link between radio waves and light was one of association: light is known to behave as a wave (Young double-slit experiment), with the same propagation speed as electromagnetic radiation. Light “proper” is also known to exist beyond the optical regime: Herschel’s experiment shows that when diffracted through a prism, sunlight warms even those parts of a desk which are not observed to be lit (first evidence of infrared light). The link between optical light and unseen electromagnetic radiation is then an easy step to make, and one confirmed through countless technological applications (e.g. optical fiber to name but one). And as soon as this link is established, a question immediately comes to the mind of the astronomer: what does the sky, our Universe, look like to the radio “eye”? Radio astronomy has a short but storied history: from Karl Jansky’s serendipitous observation of the centre of the Milky Way, which outshines our Sun in the radio regime, in 1933, to Grote Reber’s hand-built back-yard radio antenna in 1937, which successfully detected radio emission from the Milky Way itself, to such monumental projects as the Square Kilometer Array and its multiple pathfinders, it has led to countless discoveries and the opening of a truly new window on the Universe. The work presented in this thesis is a contribution to this discipline - the culmination of three years of study, which is a rather short time to get a firm grasp of radio interferometry both in theory and in practice. The need for robust, automated methods - which are improving daily, thanks to the tireless labour of the scientists in the field - is becoming ever stronger as the SKA approaches, looming large on the horizon; but even today, in the precursor era of LOFAR, MeerKAT and other pathfinders, it is keenly felt. When I started my doctorate, the sheer scale of the task at hand felt overwhelming - to actually be able to contribute to its resolution seemed daunting indeed! Thankfully, as the saying goes, no society sets for itself material goals which it cannot achieve. This thesis took place at an exciting time for radio interferometry: at the start of my doctorate, the LOFAR international stations were - to my knowledge - only beginning to be used, and even then, only tentatively; MeerKAT had not yet shown its first light; the techniques used throughout my work were still being developed. At the time of writing, great strides have been made. One of the greatest technical challenges of LOFAR - imaging using the international stations - is starting to become reality. This technical challenge is the key problem that this thesis set out to address. While we only achieved partial success so far, it is a testament to the difficulty of the task that it is not yet truly resolved. One of the major results of this thesis is a model of a bright resolved source near a famous extragalactic field: properly modeling this source not only allows the use of international LOFAR stations, but also grants deeper access to the extragalactic field itself, which is otherwise polluted by the 3C source’s sidelobes. This result was only achieved thanks to the other major result of this thesis: the development of a theoretical framework with which to better understand the effect of calibration errors on images made from interferometric data, and an algorithm to strongly mitigate them. The structure of this manuscript is as follows: we begin with an introduction to radio interferometry, LOFAR, and the emission mechanisms which dominate for our field of interest. These introductions are primarily intended to give a brief overview of the technical aspects of the data reduced in this thesis. We follow with an overview of the Measurement Equation formalism, which underpins our theoretical work. This is the keystone of this thesis. We then show the theoretical work that was developed as part of the research work done during the doctorate - which was published in Astronomy & Astrophysics. Its practical application - a quality-based weighting scheme - is used throughout our data reduction. This data reduction is the next topic of this thesis: we contextualise the scientific interest of the data we reduce, and explain both the methods and the results we achieve.
- Full Text:
Synthesis of pH responsive carriers for pulmonary drug delivery of anti-tuberculosis therapeutics: mesoporous silica nanoparticles and gelatin nanoparticles
- Authors: Ngoepe, Mpho Phehello
- Date: 2019
- Subjects: Drug delivery systems , Pulmonary pharmacology , Nanosilicon , Nanomedicine , Nanoparticles , Mesoporous materials , Silica , Tuberculosis -- Treatment
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76519 , vital:30590
- Description: Pulmonary drug delivery has historically been used as a route for delivery of therapeutics for respiratory disease management. However, while there are many advantages, there are also some serious limitations, arising mostly from the physical aspects of the inhaler devices. This is more profound when the devices are the driving force for controlling particle size generation, which results in non-uniform particles that end up being swallowed/wasted/expelled. One promising solution to overcome this limitation is to pre-formulate nano/microscale particles with a high degree of manufacturing control. Nanomedicine has advanced such that there are already several nanoparticle formulations commercially available. In the case of tuberculosis treatment, there is an opportunity not only to examine the use of nanoparticles for inhalation therapy, but to take advantage of the fact that the physiochemical environment of diseased tissue is significantly different to health lung tissue (lower pH and increased enzyme concentrations). We formulated two series of nanoparticles, whose design included moieties that could respond to pH and enzymes. To address variability, a Box-Behnken statistical approach was followed to construct mesoporous silica nanoparticles. These “hard nanoparticles” can entrap both lipophilic and hydrophilic drugs and were coated with a pH-sensitive hydrazone linker. It was observed that pH, calcination temperature and ratio of water to silica source played the greatest role, not only in controlling the physicochemical properties of the nanoparticles but also the drug release rate. A second series of nanoparticles were synthesized based on gelatin. This was done partly to add support the comparison of hard (inorganic silica) versus soft, organic particles, but also to enable enzymatic degradation and drug release. Again, diseased lung tissue expresses increased concentrations of gelatinase enzymes that could be used to stimulate drug release at the site of the disease. In addition, it was observed that the non-ionic surfactant C12E10 could interact with the protein via hydrophobic interactions thus affecting the gelatin folding. The folding states affected crosslinking with the pH responsive linker, which in turn affected the rate of drug release. To support the synthetic work, we sought to develop a unique 3D lung model directly from MRI data of tuberculosis infected lungs. This would not only permit the evaluation of our nanoparticles but could be used as a proxy for in-vivo studies in future to predict lung deposition in diseased lung. Thus, this study shows that it is possible to synthesize pH and enzyme sensitive nanoparticles for pulmonary drug delivery in the treatment and management of pulmonary tuberculosis. These particles could be loaded with either hydrophobic or hydrophilic drugs and their distribution in the airway modelled using an in-silico 3D model based on real data. Further development and verification of these results should improve treatment for pulmonary diseases and conditions such as tuberculosis. This is especially urgent in the face of multi-drug resistance and poor side effects profiles for current treatment.
- Full Text:
- Authors: Ngoepe, Mpho Phehello
- Date: 2019
- Subjects: Drug delivery systems , Pulmonary pharmacology , Nanosilicon , Nanomedicine , Nanoparticles , Mesoporous materials , Silica , Tuberculosis -- Treatment
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76519 , vital:30590
- Description: Pulmonary drug delivery has historically been used as a route for delivery of therapeutics for respiratory disease management. However, while there are many advantages, there are also some serious limitations, arising mostly from the physical aspects of the inhaler devices. This is more profound when the devices are the driving force for controlling particle size generation, which results in non-uniform particles that end up being swallowed/wasted/expelled. One promising solution to overcome this limitation is to pre-formulate nano/microscale particles with a high degree of manufacturing control. Nanomedicine has advanced such that there are already several nanoparticle formulations commercially available. In the case of tuberculosis treatment, there is an opportunity not only to examine the use of nanoparticles for inhalation therapy, but to take advantage of the fact that the physiochemical environment of diseased tissue is significantly different to health lung tissue (lower pH and increased enzyme concentrations). We formulated two series of nanoparticles, whose design included moieties that could respond to pH and enzymes. To address variability, a Box-Behnken statistical approach was followed to construct mesoporous silica nanoparticles. These “hard nanoparticles” can entrap both lipophilic and hydrophilic drugs and were coated with a pH-sensitive hydrazone linker. It was observed that pH, calcination temperature and ratio of water to silica source played the greatest role, not only in controlling the physicochemical properties of the nanoparticles but also the drug release rate. A second series of nanoparticles were synthesized based on gelatin. This was done partly to add support the comparison of hard (inorganic silica) versus soft, organic particles, but also to enable enzymatic degradation and drug release. Again, diseased lung tissue expresses increased concentrations of gelatinase enzymes that could be used to stimulate drug release at the site of the disease. In addition, it was observed that the non-ionic surfactant C12E10 could interact with the protein via hydrophobic interactions thus affecting the gelatin folding. The folding states affected crosslinking with the pH responsive linker, which in turn affected the rate of drug release. To support the synthetic work, we sought to develop a unique 3D lung model directly from MRI data of tuberculosis infected lungs. This would not only permit the evaluation of our nanoparticles but could be used as a proxy for in-vivo studies in future to predict lung deposition in diseased lung. Thus, this study shows that it is possible to synthesize pH and enzyme sensitive nanoparticles for pulmonary drug delivery in the treatment and management of pulmonary tuberculosis. These particles could be loaded with either hydrophobic or hydrophilic drugs and their distribution in the airway modelled using an in-silico 3D model based on real data. Further development and verification of these results should improve treatment for pulmonary diseases and conditions such as tuberculosis. This is especially urgent in the face of multi-drug resistance and poor side effects profiles for current treatment.
- Full Text:
Synthesis, characterisation and biological evaluation of novel anti-infective compounds bearing ferrocene, arylpyrrole, thiazolidinedione, quinoline and triazole moieties
- Authors: Oderinlo, Ogunyemi Olajide
- Date: 2019
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/114714 , vital:34016 , 10.21504/10962/114714
- Description: Expected release date-April 2022
- Full Text: false
- Authors: Oderinlo, Ogunyemi Olajide
- Date: 2019
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/114714 , vital:34016 , 10.21504/10962/114714
- Description: Expected release date-April 2022
- Full Text: false
The Afropolitan flâneur: literary representations of the city and contemporary urban identities in selected African and transnational texts
- Authors: Leff, Carol Willa
- Date: 2019
- Subjects: City and town life in literature , African literature (English) -- History and criticism , Flaneurs in literature
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115082 , vital:34076
- Description: When an individual walks the urban landscape there is a unique symbiosis between self and city. It is through walking the cityscape and observing the crowd and the surrounding environment that the archetypal literary figure of the European flâneur acts as a mirror of a particular time and space. But how might such a flâneur walk and observe the city in contemporary African and transnational literary texts? I argue that there is a literary re-imagining and repurposing of the flâneur figure which has hitherto not been acknowledged and explored: an Afropolitan flâneur. ‘Afropolitan’ is a term popularised by Taiye Selasi in a 2005 essay to refer to a ‘scattered tribe’ of ‘Africans of the world’ (n. pag.). In this dissertation, the entanglement of the Afropolitan subject and the European flâneur brings together past and present, Africa and the West. I first provide a historical and theoretical framework to illustrate how the flâneur figure ‘migrated’ from Europe to Africa, and how this figure is to be understood as a literary construct, in relation to current considerations of Afropolitanism. I go on to discuss a wide range of texts that engage with Afropolitan flâneurs who traverse cities in Africa (such as Johannesburg, Cape Town and Lagos), or global north cities (New York, Paris and London). While some of the Afropolitan flâneurs depicted in these texts are migrants or homeless individuals who struggle to adapt easily to a new environment, others, despite being more privileged, also sometimes experience uncomfortable assimilation in their new or strange city space. There are also those who seem to feel equally at home wherever they find themselves. As these Afropolitan flâneurs walk their way through the urban landscape in the texts under examination, they reflect different ways of being in the city. By problematising the binaries of local/global, national/transnational, black/white, slum/paradise, this dissertation seeks to address issues of belonging or not belonging and gestures towards new ways of understanding what it means to be an African in the world.
- Full Text:
- Authors: Leff, Carol Willa
- Date: 2019
- Subjects: City and town life in literature , African literature (English) -- History and criticism , Flaneurs in literature
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115082 , vital:34076
- Description: When an individual walks the urban landscape there is a unique symbiosis between self and city. It is through walking the cityscape and observing the crowd and the surrounding environment that the archetypal literary figure of the European flâneur acts as a mirror of a particular time and space. But how might such a flâneur walk and observe the city in contemporary African and transnational literary texts? I argue that there is a literary re-imagining and repurposing of the flâneur figure which has hitherto not been acknowledged and explored: an Afropolitan flâneur. ‘Afropolitan’ is a term popularised by Taiye Selasi in a 2005 essay to refer to a ‘scattered tribe’ of ‘Africans of the world’ (n. pag.). In this dissertation, the entanglement of the Afropolitan subject and the European flâneur brings together past and present, Africa and the West. I first provide a historical and theoretical framework to illustrate how the flâneur figure ‘migrated’ from Europe to Africa, and how this figure is to be understood as a literary construct, in relation to current considerations of Afropolitanism. I go on to discuss a wide range of texts that engage with Afropolitan flâneurs who traverse cities in Africa (such as Johannesburg, Cape Town and Lagos), or global north cities (New York, Paris and London). While some of the Afropolitan flâneurs depicted in these texts are migrants or homeless individuals who struggle to adapt easily to a new environment, others, despite being more privileged, also sometimes experience uncomfortable assimilation in their new or strange city space. There are also those who seem to feel equally at home wherever they find themselves. As these Afropolitan flâneurs walk their way through the urban landscape in the texts under examination, they reflect different ways of being in the city. By problematising the binaries of local/global, national/transnational, black/white, slum/paradise, this dissertation seeks to address issues of belonging or not belonging and gestures towards new ways of understanding what it means to be an African in the world.
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The Chase: historical and ethnographic observations on ‘Traditional Horse Racing’ in the Eastern Cape, c. 1850 to the present
- Authors: Paterson, Craig John
- Date: 2019
- Subjects: Horse racing -- South Africa -- Homelands , Masculinity -- South Africa – Homelands -- History , Migrant labor -- South Africa , Masculinity in sports -- South Africa -- Homelands Group identity -- South Africa – Homelands -- History , South Africa -- Social conditions -- 1961-1994 , South Africa -- Politics and government -- 20th century
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115328 , vital:34114
- Description: This thesis examines the development of a horse racing sport, umdyarho wamahashe, as it is practised in the former-bantustans of the Eastern Cape Province. Using varied source material – ethnographic, archival and oral – it provides a guide to understanding the historical development of umdyarho events and their meaning to participants. By drawing together available ‘fragments’ of material on horses and horse racing in the former-bantustans of Transkei and Ciskei, it argues that horse racing is derived from a pre-colonial cattle racing tradition which was made impossible by a collision of environmental pressures and colonial responses to them. It goes on to show how horses came to take on a ‘symbol set’ of masculine power and “growing up.” The nexus of horses, rapidly assimilated into daily life, and the changing material conditions confronting the people of the Eastern Cape, made horse racing an ideal outlet through which men might regain a sense of power in conditions which eroded their sense of control over their daily lives, and, as a result, their perceived masculinity. This thesis argues that through horse races, people of the Eastern Cape were provided an space in which they could at once celebrate their legacy (by acting as their ‘forebears’ did) and their potential (by showing who they would like to be, through the deployment of the horse as a symbol). It concludes by discussing and how the imposition of change from outside threatens the ‘spirit’ of this sport.
- Full Text:
- Authors: Paterson, Craig John
- Date: 2019
- Subjects: Horse racing -- South Africa -- Homelands , Masculinity -- South Africa – Homelands -- History , Migrant labor -- South Africa , Masculinity in sports -- South Africa -- Homelands Group identity -- South Africa – Homelands -- History , South Africa -- Social conditions -- 1961-1994 , South Africa -- Politics and government -- 20th century
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115328 , vital:34114
- Description: This thesis examines the development of a horse racing sport, umdyarho wamahashe, as it is practised in the former-bantustans of the Eastern Cape Province. Using varied source material – ethnographic, archival and oral – it provides a guide to understanding the historical development of umdyarho events and their meaning to participants. By drawing together available ‘fragments’ of material on horses and horse racing in the former-bantustans of Transkei and Ciskei, it argues that horse racing is derived from a pre-colonial cattle racing tradition which was made impossible by a collision of environmental pressures and colonial responses to them. It goes on to show how horses came to take on a ‘symbol set’ of masculine power and “growing up.” The nexus of horses, rapidly assimilated into daily life, and the changing material conditions confronting the people of the Eastern Cape, made horse racing an ideal outlet through which men might regain a sense of power in conditions which eroded their sense of control over their daily lives, and, as a result, their perceived masculinity. This thesis argues that through horse races, people of the Eastern Cape were provided an space in which they could at once celebrate their legacy (by acting as their ‘forebears’ did) and their potential (by showing who they would like to be, through the deployment of the horse as a symbol). It concludes by discussing and how the imposition of change from outside threatens the ‘spirit’ of this sport.
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The conservation, ecology, and distribution of the critically endangered Encephalartos latifrons Lehm
- Authors: Swart, Carin
- Date: 2019
- Subjects: Encephalartos , Cycadaceae , Cycads -- Conservation -- South Africa , Botany, Economic -- South Africa , Rare plants -- South Africa , Endangered plants -- South Africa , Wild plant trade -- Law and legislation -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/94483 , vital:31049
- Description: Cycads have attracted global attention both as horticulturally interesting and often valuable plants; but also as some of the most threatened organisms on the planet. In this thesis I investigate the conservation management, biology, reproductive ecology and distribution of Encephalartos latifrons populations in the wild and draw out conclusions on how best to conserve global cycad biodiversity. I also employ computer-modelling techniques in some of the chapters of this thesis to demonstrate how to improve conservation outcomes for E. latifrons and endangered species in general, where information on the distribution, biology and habitat requirements of such species are inherently limited, often precluding robust conservation decision-making. In Chapter 1 of this thesis I introduce the concept of extinction debt and elucidate the importance of in situ cycad conservation. I explain how the concept of extinction debt relates to single species, as well as give details on the mechanisms causing extinction debt in cycad populations. I introduce the six extinction trajectory threshold model and how this relates to extinction debt in cycads. I discuss the vulnerability of cycads to extinction and give an overview of biodiversity policy in South Africa. I expand on how national and global policies contribute to cycad conservation and present various global initiatives that support threatened species conservation. I conclude Chapter 1 by explaining how computer-based models can assist conservation decision-making for rare, threatened, and endangered species in the face of uncertainty. Chapter 2 of this thesis illustrates how a modelling approach, using limited available historical and present day locality information, is a feasible method to determine areas of suitable habitat for E. latifrons and other critically endangered cycad species where locality information is inherently uncommon. Results from this chapter show that conservation planning through structured decision-making may be improved by the use of computer models, even when locality data are limited. These results may be incorporated into biodiversity conservation plans or used to assist conservation-decision makers when undertaking recovery efforts for E. latifrons and may provide guidance to conservation planners and policy makers when undertaking conservation plans to improve cycad biodiversity both nationally and globally. There was limited information available in the biology and ecological requirements of E. latifrons. This information is important when making policy decisions such as the publication of non-detriment findings and compiling biodiversity management plans for this and other cycad species. Chapter 3 investigates the life-history, population structure, fire response and survival of an in situ E. latifrons population. A demographic census was undertaken between 2013 and 2017 on a previously undiscovered population. Population characteristics of the “new” population were compared to the demographics of a well-known and intensively managed population. Results of this chapter show that at least one in situ E. latifrons population is stable and increasing under current environmental conditions. Importantly, the population is naturally recruiting seedlings without the need for artificial pollination. Demographic information described in this chapter is a necessary precursor to undertaking a Population Viability Assessment for the species. This will assist conservation decision-makers when determining the best conservation management strategy for E. latifrons. It may also be useful to apply generalisatons to other cycad species (with similar life-histories and habitat requirements) where there is limited information available on the species biological and ecological requirements, restricting robust policy conservation decision-making. It was important for this study to determine the extent and variety of cone fauna within existing E. latifrons wild populations. Previous anecdotal evidence suggested that E. latifrons is functionally extinct as a species, but evidence to the contrary was found when a healthy, self-sustaining wild population was discovered to be naturally recruiting. It was important to establish the existence and diversity of male cone faunal species (an important breeding site for weevil pollinators) within wild populations. Chapter 4 set out to determine if potential pollinators exist in the wild and if so, how diverse are they and in what numbers. This is the first comprehensive analysis of cone fauna present in wild E. latifrons populations. Equally important was the need to determine if wild populations are capable of producing viable seeds under conditions conducive to natural pollination. Results of this chapter show that there is a relatively high diversity of insect fauna in the male cones of some wild E. latifrons populations. Furthermore, some wild populations are capable of producing viable seeds through natural pollination; even though they may not be naturally recruiting seedlings into the population. A staggered germination pattern displayed by one of the wild E. latifrons populations was studied, suggesting the evolution of an adaptive trait given the stochastic environment (climatically and disturbances such as fire) within which E. latifrons populations may be found. Species recovery (restoration and/or population augmentation) may be the only conservation solution remaining to save endangered species such as E. latifrons from extinction in the wild. Chapter 5 involves the return of 25 seedlings germinated as part of a seed viability experiment (see Chapter 4) back into a wild population from where they originated. The primary threat to seedling survival at the site was livestock activity (grazing/trampling). The population was subsequently fenced off to mitigate this threat and seedlings planted both inside and outside a fenced area to establish if there was a difference in seedling survival between the unprotected and protected sites. A high percentage (92%) of seedlings planted perished in total. None of the seedlings planted outside the fenced area survived over the monitoring period, while only two seedlings planted within the fenced area survived. Survival of the seedlings inside the fenced area was only after placing individual cages on the seedlings to prevent further losses. The primary causes of death for all seedlings included uprooting, and defoliation with some of the seedlings missing completely. This chapter found that the lack of natural seedling recruitment at the site was as a result of livestock activity. Grazing by livestock poses a significant threat to natural recruitment in some E. latifrons populations. Alternative restoration methods are suggested and protection of seedlings while undertaking a restoration/augmentation programme is emphasised. Developing conservation management plans for rare and/or endangered species is often met with high levels of uncertainty, particularly if there is limited information available on the biology and ecological requirements for the species concerned. Population viability analysis (PVA) is often suggested as a tool to determine conservation management scenarios that may enhance wild population persistence. The standard PVA approach is however problematic as it is a time-consuming process requiring the collection of demographic data over long time periods. In addition, the PVA approach does not take in to account non-biological factors which may impede the effective implementation of conservation plans. Chapter 6 of this thesis makes use of a Multi-Criteria Decision Making (MCDM) approach called the Analytical Hierarchy Process (AHP) to decide on the best conservation management strategy for an E. latifrons population. Sensitivity analysis was completed to test the robustness of the decision and to identify which criteria influenced the original results. In this study, the development of the decision tree and criteria judgements, were made solely by the researcher. It is emphasised that the decision outcome may be biased if not conducted as part of a multi-stakeholder workshop using the same approach. Nevertheless, it is recommended that a Population Viability Risk Management (PVRM) assessment be undertaken for E. latifrons using an MCDM approach such as AHP as a prestudy, before the revision of the Biodiversity Management Plan (BMP) for E. latifrons. This method is particularly useful when non-biological criteria are to be incorporated into the decision-making process. It is also a viable and holistic alternative to the standard PVA approach when developing conservation management plans for rare and endangered species. In Chapter 7 I review the concept of extinction debt in cycads using E. latifrons as an example. I assimilate historical information to understand mechanisms that may have impacted on E. latifrons populations in the past. This was done to understand the scale of extinction time lags on E. latifrons and to relate this to its present position on the exitinction trajectory. I recommend aligning South African policies and biodiversity assessments with international initiatives and draw out general conclusions for the conservation of global cycad biodiversity. I conclude by recommending further research for E. latifrons.
- Full Text:
- Authors: Swart, Carin
- Date: 2019
- Subjects: Encephalartos , Cycadaceae , Cycads -- Conservation -- South Africa , Botany, Economic -- South Africa , Rare plants -- South Africa , Endangered plants -- South Africa , Wild plant trade -- Law and legislation -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/94483 , vital:31049
- Description: Cycads have attracted global attention both as horticulturally interesting and often valuable plants; but also as some of the most threatened organisms on the planet. In this thesis I investigate the conservation management, biology, reproductive ecology and distribution of Encephalartos latifrons populations in the wild and draw out conclusions on how best to conserve global cycad biodiversity. I also employ computer-modelling techniques in some of the chapters of this thesis to demonstrate how to improve conservation outcomes for E. latifrons and endangered species in general, where information on the distribution, biology and habitat requirements of such species are inherently limited, often precluding robust conservation decision-making. In Chapter 1 of this thesis I introduce the concept of extinction debt and elucidate the importance of in situ cycad conservation. I explain how the concept of extinction debt relates to single species, as well as give details on the mechanisms causing extinction debt in cycad populations. I introduce the six extinction trajectory threshold model and how this relates to extinction debt in cycads. I discuss the vulnerability of cycads to extinction and give an overview of biodiversity policy in South Africa. I expand on how national and global policies contribute to cycad conservation and present various global initiatives that support threatened species conservation. I conclude Chapter 1 by explaining how computer-based models can assist conservation decision-making for rare, threatened, and endangered species in the face of uncertainty. Chapter 2 of this thesis illustrates how a modelling approach, using limited available historical and present day locality information, is a feasible method to determine areas of suitable habitat for E. latifrons and other critically endangered cycad species where locality information is inherently uncommon. Results from this chapter show that conservation planning through structured decision-making may be improved by the use of computer models, even when locality data are limited. These results may be incorporated into biodiversity conservation plans or used to assist conservation-decision makers when undertaking recovery efforts for E. latifrons and may provide guidance to conservation planners and policy makers when undertaking conservation plans to improve cycad biodiversity both nationally and globally. There was limited information available in the biology and ecological requirements of E. latifrons. This information is important when making policy decisions such as the publication of non-detriment findings and compiling biodiversity management plans for this and other cycad species. Chapter 3 investigates the life-history, population structure, fire response and survival of an in situ E. latifrons population. A demographic census was undertaken between 2013 and 2017 on a previously undiscovered population. Population characteristics of the “new” population were compared to the demographics of a well-known and intensively managed population. Results of this chapter show that at least one in situ E. latifrons population is stable and increasing under current environmental conditions. Importantly, the population is naturally recruiting seedlings without the need for artificial pollination. Demographic information described in this chapter is a necessary precursor to undertaking a Population Viability Assessment for the species. This will assist conservation decision-makers when determining the best conservation management strategy for E. latifrons. It may also be useful to apply generalisatons to other cycad species (with similar life-histories and habitat requirements) where there is limited information available on the species biological and ecological requirements, restricting robust policy conservation decision-making. It was important for this study to determine the extent and variety of cone fauna within existing E. latifrons wild populations. Previous anecdotal evidence suggested that E. latifrons is functionally extinct as a species, but evidence to the contrary was found when a healthy, self-sustaining wild population was discovered to be naturally recruiting. It was important to establish the existence and diversity of male cone faunal species (an important breeding site for weevil pollinators) within wild populations. Chapter 4 set out to determine if potential pollinators exist in the wild and if so, how diverse are they and in what numbers. This is the first comprehensive analysis of cone fauna present in wild E. latifrons populations. Equally important was the need to determine if wild populations are capable of producing viable seeds under conditions conducive to natural pollination. Results of this chapter show that there is a relatively high diversity of insect fauna in the male cones of some wild E. latifrons populations. Furthermore, some wild populations are capable of producing viable seeds through natural pollination; even though they may not be naturally recruiting seedlings into the population. A staggered germination pattern displayed by one of the wild E. latifrons populations was studied, suggesting the evolution of an adaptive trait given the stochastic environment (climatically and disturbances such as fire) within which E. latifrons populations may be found. Species recovery (restoration and/or population augmentation) may be the only conservation solution remaining to save endangered species such as E. latifrons from extinction in the wild. Chapter 5 involves the return of 25 seedlings germinated as part of a seed viability experiment (see Chapter 4) back into a wild population from where they originated. The primary threat to seedling survival at the site was livestock activity (grazing/trampling). The population was subsequently fenced off to mitigate this threat and seedlings planted both inside and outside a fenced area to establish if there was a difference in seedling survival between the unprotected and protected sites. A high percentage (92%) of seedlings planted perished in total. None of the seedlings planted outside the fenced area survived over the monitoring period, while only two seedlings planted within the fenced area survived. Survival of the seedlings inside the fenced area was only after placing individual cages on the seedlings to prevent further losses. The primary causes of death for all seedlings included uprooting, and defoliation with some of the seedlings missing completely. This chapter found that the lack of natural seedling recruitment at the site was as a result of livestock activity. Grazing by livestock poses a significant threat to natural recruitment in some E. latifrons populations. Alternative restoration methods are suggested and protection of seedlings while undertaking a restoration/augmentation programme is emphasised. Developing conservation management plans for rare and/or endangered species is often met with high levels of uncertainty, particularly if there is limited information available on the biology and ecological requirements for the species concerned. Population viability analysis (PVA) is often suggested as a tool to determine conservation management scenarios that may enhance wild population persistence. The standard PVA approach is however problematic as it is a time-consuming process requiring the collection of demographic data over long time periods. In addition, the PVA approach does not take in to account non-biological factors which may impede the effective implementation of conservation plans. Chapter 6 of this thesis makes use of a Multi-Criteria Decision Making (MCDM) approach called the Analytical Hierarchy Process (AHP) to decide on the best conservation management strategy for an E. latifrons population. Sensitivity analysis was completed to test the robustness of the decision and to identify which criteria influenced the original results. In this study, the development of the decision tree and criteria judgements, were made solely by the researcher. It is emphasised that the decision outcome may be biased if not conducted as part of a multi-stakeholder workshop using the same approach. Nevertheless, it is recommended that a Population Viability Risk Management (PVRM) assessment be undertaken for E. latifrons using an MCDM approach such as AHP as a prestudy, before the revision of the Biodiversity Management Plan (BMP) for E. latifrons. This method is particularly useful when non-biological criteria are to be incorporated into the decision-making process. It is also a viable and holistic alternative to the standard PVA approach when developing conservation management plans for rare and endangered species. In Chapter 7 I review the concept of extinction debt in cycads using E. latifrons as an example. I assimilate historical information to understand mechanisms that may have impacted on E. latifrons populations in the past. This was done to understand the scale of extinction time lags on E. latifrons and to relate this to its present position on the exitinction trajectory. I recommend aligning South African policies and biodiversity assessments with international initiatives and draw out general conclusions for the conservation of global cycad biodiversity. I conclude by recommending further research for E. latifrons.
- Full Text: