Microcystin enhances the fitness of microcystin producing cyanobacteria at high light intensities by either preventing or retarding photoinhibition
- Authors: Phelan, Richard Reginald
- Date: 2013
- Subjects: Microcystins , Microcystis , Cyanobacterial toxins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10354 , http://hdl.handle.net/10948/d1020957
- Description: Several genera of cyanobacteria produce microcystin, a monocyclic peptide, with a unique chemical structure. To date, there have been over a 100 different structural variants of microcystin which have been identified. Microcystin production is affected by numerous environmental factors. However, the primary modulating factor for intracellular microcystin quota is the intracellular N:C ratio. No clearly defined biological role has been described for microcystin. Proposed roles for microcystin include defence against plankton grazers, metal chelation, an infochemical and a protectant against oxidative stress. There is sufficient evidence to support a biological role for microcystin in photosynthesis: microcystin is predominantly located in the thylakoid membranes, the microcystin gene cluster is differentially expressed as a function of light and a growth advantage for the microcystin producer in saturating light intensities. The purpose of this study is to investigate a possible biological role for microcystin in preventing photoinhibition and thus explaining the growth advantage observed in toxin-producers over non-toxin-producers. The uptake of exogenous microcystin was observed in Synechocystis PCC 6803 which was internalized and located in the thylakoid membranes and caused the inhibition of photosynthesis. Microcystin variants and increasing concentrations of microcystin-LR had no effect on the fluidity of the thylakoid membranes. The exposure of thylakoid membranes from Synechocystis PCC 6803 to physiologically relevant concentrations of different microcystin variants resulted in the inhibition of photosystem II activity but not photosystem I activity. The inhibition of photosystem II was variant dependent and concentration dependent for microcystin-LR and microcystin-RR. Chlorophyll a fluorescence data showed that photosystem II inhibition was caused by the inhibition of the oxygen evolving complex. Furthermore, a completion study revealed that the microcystin-producing Microcystis PCC 7806 had a competitive advantage over the non-microcystin producing ΔmcyA mutant of Microcystis PCC 7806 at high light intensities. The data indicates that microcystin protects the toxin-producer by either retarding or preventing photoinhibition and thus identifying the first data supported function for microcystin in cyanobacteria.
- Full Text:
- Date Issued: 2013
- Authors: Phelan, Richard Reginald
- Date: 2013
- Subjects: Microcystins , Microcystis , Cyanobacterial toxins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10354 , http://hdl.handle.net/10948/d1020957
- Description: Several genera of cyanobacteria produce microcystin, a monocyclic peptide, with a unique chemical structure. To date, there have been over a 100 different structural variants of microcystin which have been identified. Microcystin production is affected by numerous environmental factors. However, the primary modulating factor for intracellular microcystin quota is the intracellular N:C ratio. No clearly defined biological role has been described for microcystin. Proposed roles for microcystin include defence against plankton grazers, metal chelation, an infochemical and a protectant against oxidative stress. There is sufficient evidence to support a biological role for microcystin in photosynthesis: microcystin is predominantly located in the thylakoid membranes, the microcystin gene cluster is differentially expressed as a function of light and a growth advantage for the microcystin producer in saturating light intensities. The purpose of this study is to investigate a possible biological role for microcystin in preventing photoinhibition and thus explaining the growth advantage observed in toxin-producers over non-toxin-producers. The uptake of exogenous microcystin was observed in Synechocystis PCC 6803 which was internalized and located in the thylakoid membranes and caused the inhibition of photosynthesis. Microcystin variants and increasing concentrations of microcystin-LR had no effect on the fluidity of the thylakoid membranes. The exposure of thylakoid membranes from Synechocystis PCC 6803 to physiologically relevant concentrations of different microcystin variants resulted in the inhibition of photosystem II activity but not photosystem I activity. The inhibition of photosystem II was variant dependent and concentration dependent for microcystin-LR and microcystin-RR. Chlorophyll a fluorescence data showed that photosystem II inhibition was caused by the inhibition of the oxygen evolving complex. Furthermore, a completion study revealed that the microcystin-producing Microcystis PCC 7806 had a competitive advantage over the non-microcystin producing ΔmcyA mutant of Microcystis PCC 7806 at high light intensities. The data indicates that microcystin protects the toxin-producer by either retarding or preventing photoinhibition and thus identifying the first data supported function for microcystin in cyanobacteria.
- Full Text:
- Date Issued: 2013
Modulation of Plasmodium falciparum chaperones PfHsp70-1 and PfHsp70-x by small molecules
- Authors: Cockburn, Ingrid Louise
- Date: 2013
- Subjects: Plasmodium falciparum Heat shock proteins Molecular chaperones Homeostasis Protein folding Malaria Antimalarials Escherichia coli
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3887 , http://hdl.handle.net/10962/d1001747
- Description: The heat shock proteins of ~ 70 kDa (Hsp70s) are a conserved group of molecular chaperones important in maintaining the protein homeostasis in cells, carrying out functions including refolding of misfolded or unfolded proteins. Hsp70s function in conjunction with a number of other proteins including Hsp40 cochaperones. Central to the regulation Hsp70 activity is the Hsp70 ATPase cycle, involving ATP hydrolysis by Hsp70, and stimulation of this ATP hydrolysis by Hsp40. PfHsp70-1, the major cytosolic Hsp70 in the malaria parasite, Plasmodium falciparum, and PfHsp70-x, a novel malarial Hsp70 recently found to be exported to the host cell cytosol during the erythrocytic stages of the P. falciparum lifecycle, are both thought to play important roles in the malaria parasite’s survival and virulence, and thus represent novel antimalarial targets. Modulation of the function of these proteins by small molecules could thus lead to the development of antimalarials with novel targets and mechanisms. In the present study, malarial Hsp70s (PfHsp70-1 and PfHsp70-x), human Hsp70 (HSPA1A), malarial Hsp40 (PfHsp40) and human Hsp40 (Hsj1a) were recombinantly produced in Escherichia coli. In a characterisation of the chaperone activity of recombinant PfHsp70-x, the protein was found to have a basal ATPase activity (15.7 nmol ATP/min/mg protein) comparable to that previously described for PfHsp70-1, and an aggregation suppression activity significantly higher than that of PfHsp70-1. In vitro assays were used to screen five compounds of interest (lapachol, bromo-β-lapachona and malonganenones A, B and C) belonging to two compound classes (1,4 naphthoquinones and prenylated alkaloids) for modulatory effects on PfHsp70-1, PfHsp70-x and HsHsp70. A wide range of effects by compounds on the chaperone activities of Hsp70s was observed, including differential effects by compounds on different Hsp70s despite high conservation (≥ 70 % sequence identity) between the Hsp70s. The five compounds were shown to interact with all three Hsp70s in in vitro binding studies. Differential modulation by compounds was observed between the Hsj1a-stimulated ATPase activities of different Hsp70s, suggestive of not only a high degree of specificity of compounds to chaperone systems, but also distinct interactions between different Hsp70s and Hjs1a. The effects of compounds on the survival of P. falciparum parasites as well as mammalian cells was assessed. Bromo-β-lapachona was found to have broad effects across all systems, modulating the chaperone activities of all three Hsp70s, and showing significant toxicity toward both P. falciparum parasites and mammalian cells in culture. Malonganenone A was found to modulate only the malarial Hsp70s, not human Hsp70, showing significant toxicity toward malarial parasites (IC₅₀ ~ 0.8 μM), and comparatively low toxicity toward mammalian cells, representing therefore a novel starting point for a new class of antimalarials potentially targeting a new antimalarial drug target, Hsp70.
- Full Text:
- Date Issued: 2013
- Authors: Cockburn, Ingrid Louise
- Date: 2013
- Subjects: Plasmodium falciparum Heat shock proteins Molecular chaperones Homeostasis Protein folding Malaria Antimalarials Escherichia coli
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3887 , http://hdl.handle.net/10962/d1001747
- Description: The heat shock proteins of ~ 70 kDa (Hsp70s) are a conserved group of molecular chaperones important in maintaining the protein homeostasis in cells, carrying out functions including refolding of misfolded or unfolded proteins. Hsp70s function in conjunction with a number of other proteins including Hsp40 cochaperones. Central to the regulation Hsp70 activity is the Hsp70 ATPase cycle, involving ATP hydrolysis by Hsp70, and stimulation of this ATP hydrolysis by Hsp40. PfHsp70-1, the major cytosolic Hsp70 in the malaria parasite, Plasmodium falciparum, and PfHsp70-x, a novel malarial Hsp70 recently found to be exported to the host cell cytosol during the erythrocytic stages of the P. falciparum lifecycle, are both thought to play important roles in the malaria parasite’s survival and virulence, and thus represent novel antimalarial targets. Modulation of the function of these proteins by small molecules could thus lead to the development of antimalarials with novel targets and mechanisms. In the present study, malarial Hsp70s (PfHsp70-1 and PfHsp70-x), human Hsp70 (HSPA1A), malarial Hsp40 (PfHsp40) and human Hsp40 (Hsj1a) were recombinantly produced in Escherichia coli. In a characterisation of the chaperone activity of recombinant PfHsp70-x, the protein was found to have a basal ATPase activity (15.7 nmol ATP/min/mg protein) comparable to that previously described for PfHsp70-1, and an aggregation suppression activity significantly higher than that of PfHsp70-1. In vitro assays were used to screen five compounds of interest (lapachol, bromo-β-lapachona and malonganenones A, B and C) belonging to two compound classes (1,4 naphthoquinones and prenylated alkaloids) for modulatory effects on PfHsp70-1, PfHsp70-x and HsHsp70. A wide range of effects by compounds on the chaperone activities of Hsp70s was observed, including differential effects by compounds on different Hsp70s despite high conservation (≥ 70 % sequence identity) between the Hsp70s. The five compounds were shown to interact with all three Hsp70s in in vitro binding studies. Differential modulation by compounds was observed between the Hsj1a-stimulated ATPase activities of different Hsp70s, suggestive of not only a high degree of specificity of compounds to chaperone systems, but also distinct interactions between different Hsp70s and Hjs1a. The effects of compounds on the survival of P. falciparum parasites as well as mammalian cells was assessed. Bromo-β-lapachona was found to have broad effects across all systems, modulating the chaperone activities of all three Hsp70s, and showing significant toxicity toward both P. falciparum parasites and mammalian cells in culture. Malonganenone A was found to modulate only the malarial Hsp70s, not human Hsp70, showing significant toxicity toward malarial parasites (IC₅₀ ~ 0.8 μM), and comparatively low toxicity toward mammalian cells, representing therefore a novel starting point for a new class of antimalarials potentially targeting a new antimalarial drug target, Hsp70.
- Full Text:
- Date Issued: 2013
Molecular signaling in colorectal carcinogenesis : the roles and relationships of beta-catenin, PPARgamma and COX-2
- Authors: Fredericks, Ernst
- Date: 2013
- Subjects: Colon (Anatomy) -- Cancer , Cyclooxygenase 2 , Peroxisomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10357 , http://hdl.handle.net/10948/d1021014
- Description: Colorectal cancer (CRC) is a common disease with significant morbidity and mortality. In spite of significant advances in understanding the molecular signaling in this disorder, unanswered questions remain. Cyclooxygenase-2 (COX-2) and β-catenin have established roles in colorectal carcinogenesis, with both being upregulated early in the disease course. The role of peroxisome proliferator-activated receptor γ (PPARγ) is less clear, but has been shown to be downregulated in colon cancer models. Butyrate, a short chain fatty acid, produced by colon microbiota and transported into the colonocyte by transporter proteins, appears to be important in early carcinogenesis. The butyrate concentration is reduced in CRC and so are its transporters. Interleukin-17 (IL-17) plays a role in colitis-associated colorectal cancer (CAC), but its function in sporadic CRC is less clear. Similarly, Protein kinase C (PKC) has proven involvement in many solid tumours, including CRC, but its exact mechanistic role is still speculative. AIM: To investigate the role and possible signaling pathways of the major role players, β-catenin, COX-2 and PPARγ in early CRC. Further, to elucidate the mechanistic pathways of butyrate and its transporters, IL-17 and PKC in CRC. METHOD: Informed consent was obtained for all patients. Patients were recruited in various disease categories, including normal, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and CRC. Colon biopsy specimens were obtained during colonoscopy and used for immunohistochemistry (IHC) and gene expression analysis of the above genes by quantitative polymerase chain reaction (qPCR). RESULTS: β-catenin mRNA and protein expression was increased in CRC and the IBD groups compared to the normal group, while it was reduced in the IBS groups. COX-2 mRNA expression showed a steady increase from normal, through IBS, IBD and CRC groups to a statistically significant degree. The COX-2 protein expression, however, did not match the mRNA expression with increased COX-2 protein expression in normal and IBS groups and reduced expression in IBD and CRC groups. PPARγ mRNA expression was unchanged in IBD and CRC groups, but significantly increased in the IBS group compared to normal. Butyrate transporter, SLC16A1 mRNA was significantly reduced in CRC, but also in the IBS groups, which was unexpected. In the IBD group, SLC16A1 mRNA was unchanged in Crohn’s disease (CD) but significantly reduced in ulcerative colitis (UC). Similarly, SLC5A8 mRNA expression was significantly reduced in the CRC as well as the IBS groups. In the IBD groups, SLC5A8 was unchanged in UC but significantly increased in CD. IL-17 mRNA expression was significantly reduced in CRC and IBS groups, but unchanged in the IBD groups. PKCε mRNA was significantly increased in CRC as expected. In the IBD groups, PKCε mRNA was unchanged in CD but significantly increased in UC. In the IBS groups, PKCε mRNA in constipation –IBS (C-IBS) was significantly reduced, but unchanged in diarrhoea – IBS (D-IBS). CONCLUSIONS: β-catenin mRNA and protein expression was increased in CRC and the CRC promoting IBD groups. COX-2 protein expression was incongruent with the COX-2 mRNA expression and this may reflect homeostatic control mechanisms. High COX-2 mRNA expression in CRC and CRC promoting IBD groups may be a secondary phenomenon reflecting the inflammatory milieu, rather than a true carcinogenesis-related event. PPARγ does not appear to play a central role in early colon carcinogenesis, in spite of available literature suggesting otherwise. Butyrate transporters showed inconsistent results and for now no firm conclusions can be drawn from this. IL-17 may play a role in CAC as confirmed in this and other studies, but its role in sporadic CRC is tenuous and requires further investigation. Likewise for PKCε, upregulation is associated with increased tumourigenecity as shown in this study, however, the mechanistic pathway(s) involved is still speculative and requires further study.
- Full Text:
- Date Issued: 2013
- Authors: Fredericks, Ernst
- Date: 2013
- Subjects: Colon (Anatomy) -- Cancer , Cyclooxygenase 2 , Peroxisomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10357 , http://hdl.handle.net/10948/d1021014
- Description: Colorectal cancer (CRC) is a common disease with significant morbidity and mortality. In spite of significant advances in understanding the molecular signaling in this disorder, unanswered questions remain. Cyclooxygenase-2 (COX-2) and β-catenin have established roles in colorectal carcinogenesis, with both being upregulated early in the disease course. The role of peroxisome proliferator-activated receptor γ (PPARγ) is less clear, but has been shown to be downregulated in colon cancer models. Butyrate, a short chain fatty acid, produced by colon microbiota and transported into the colonocyte by transporter proteins, appears to be important in early carcinogenesis. The butyrate concentration is reduced in CRC and so are its transporters. Interleukin-17 (IL-17) plays a role in colitis-associated colorectal cancer (CAC), but its function in sporadic CRC is less clear. Similarly, Protein kinase C (PKC) has proven involvement in many solid tumours, including CRC, but its exact mechanistic role is still speculative. AIM: To investigate the role and possible signaling pathways of the major role players, β-catenin, COX-2 and PPARγ in early CRC. Further, to elucidate the mechanistic pathways of butyrate and its transporters, IL-17 and PKC in CRC. METHOD: Informed consent was obtained for all patients. Patients were recruited in various disease categories, including normal, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and CRC. Colon biopsy specimens were obtained during colonoscopy and used for immunohistochemistry (IHC) and gene expression analysis of the above genes by quantitative polymerase chain reaction (qPCR). RESULTS: β-catenin mRNA and protein expression was increased in CRC and the IBD groups compared to the normal group, while it was reduced in the IBS groups. COX-2 mRNA expression showed a steady increase from normal, through IBS, IBD and CRC groups to a statistically significant degree. The COX-2 protein expression, however, did not match the mRNA expression with increased COX-2 protein expression in normal and IBS groups and reduced expression in IBD and CRC groups. PPARγ mRNA expression was unchanged in IBD and CRC groups, but significantly increased in the IBS group compared to normal. Butyrate transporter, SLC16A1 mRNA was significantly reduced in CRC, but also in the IBS groups, which was unexpected. In the IBD group, SLC16A1 mRNA was unchanged in Crohn’s disease (CD) but significantly reduced in ulcerative colitis (UC). Similarly, SLC5A8 mRNA expression was significantly reduced in the CRC as well as the IBS groups. In the IBD groups, SLC5A8 was unchanged in UC but significantly increased in CD. IL-17 mRNA expression was significantly reduced in CRC and IBS groups, but unchanged in the IBD groups. PKCε mRNA was significantly increased in CRC as expected. In the IBD groups, PKCε mRNA was unchanged in CD but significantly increased in UC. In the IBS groups, PKCε mRNA in constipation –IBS (C-IBS) was significantly reduced, but unchanged in diarrhoea – IBS (D-IBS). CONCLUSIONS: β-catenin mRNA and protein expression was increased in CRC and the CRC promoting IBD groups. COX-2 protein expression was incongruent with the COX-2 mRNA expression and this may reflect homeostatic control mechanisms. High COX-2 mRNA expression in CRC and CRC promoting IBD groups may be a secondary phenomenon reflecting the inflammatory milieu, rather than a true carcinogenesis-related event. PPARγ does not appear to play a central role in early colon carcinogenesis, in spite of available literature suggesting otherwise. Butyrate transporters showed inconsistent results and for now no firm conclusions can be drawn from this. IL-17 may play a role in CAC as confirmed in this and other studies, but its role in sporadic CRC is tenuous and requires further investigation. Likewise for PKCε, upregulation is associated with increased tumourigenecity as shown in this study, however, the mechanistic pathway(s) involved is still speculative and requires further study.
- Full Text:
- Date Issued: 2013
Monitoring carbon stocks in the sub-tropical thicket biome using remote sensing and GIS techniques : the case of the Great Fish River Nature Reserve and its environs, Eastern Cape province, South Africa
- Authors: Nyamugama, Adolph
- Date: 2013
- Subjects: Fragmented landscapes -- South Africa -- Eastern Cape -- Remote sensing , Environmental degradation -- South Africa -- Eastern Cape , Remote sensing , Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10672 , http://hdl.handle.net/10948/d1020303
- Description: The subtropical thicket biome in the Eastern Cape Province of South Africa has been heavily degraded and transformed due overutilization during the last century. The highly degraded and transformed areas exhibit a significant loss of above ground carbon stocks (AGC) and loss of SOC content. Information about land use /cover change and fragmentation dynamics is a prerequisite for measuring carbon stock changes. The main aim of this study is to assess the trends of land use/cover change, fragmentation dynamics, model the temporal changes of AGC stocks in the Great Fish River Nature Reserve and its environs from 1972 to 2010, quantify and map the spatial distribution of SOC concentrations in the partial subtropical thicket cover in the Great Fish River Nature Reserve and environs (communal rangelands). Multi-temporal analyses based on 1972 Landsat MSS, 1982 and 1992 Landsat TM, 2002 Landsat ETM and 2010 SPOT 5 High Resolution images were used for land use/cover change detection and fragmentation analysis. Object oriented post-classification comparison was applied for land use/cover change detection analysis. Fragmentation dynamics analysis was carried out by computing and analyzing landscape metrics in land use/cover classes. Landscape fragmentation analyses revealed that thicket vegetation has increasingly become fragmented, characterized by smaller less linked patches of intact thicket cover. Landscape metrics for intact thicket and degraded thicket classes reflected fragmentation, as illustrated by the increase in the Number of Patches (NP), Patch Density (PD), Landscape Shape Index (LSI), and a decrease in Mean Patch Size (MPS). The use of remote sensing techniques and landscape metrics was vital for the understanding of the dynamics of land use/cover change and fragmentation. Baseline land use/cover maps produced for 1972, 1982, 1992 2002 and 2010 and fragmentation analyses were then used for analyzing carbon stock changes in the study area. To model the temporal changes of AGC stocks in the Great Fish River Nature Reserve and its environs from 1972 to 2010, a method based on the integration of RS and GIS was employed for the estimation of AGC stocks in a time series. A non-linear regression model was developed using NDVI values generated from SPOT 5 HRG satellite imagery of 2010 as the independent variable and AGC stock estimates from field plots as the dependent variable. The regression model was used to estimate AGC stocks for the entire study area on the 2010 SPOT 5 HRG and also extrapolated to the 1972 Landsat MSS, 1982 and 1992 Landsat TM, and 2002 Landsat ETM. The AGC stocks for the period 1972 -1982, 1982-1992, 1992-200) and 2002-2010 were compared by means of change detection analysis. The comparison of AGC stocks was carried out at subtropical thicket class level. The results showed a decline of AGC stocks in all the classes from 1972 to 2010. Degraded and transformed thicket classes had the highest AGC stock losses. The decline of AGC stocks was attributed to thicket transformation and degradation which were caused by anthropogenic activities. To map and quantify SOC concentration in partial (fractional) thicket vegetation cover, the spectral reflectance of both thicket vegetation and bare-soils was measured in situ. Soil samples were collected from the sampling sites and transported to the laboratory for spectral reflectance and SOC measurements. Thicket vegetation and bare soil reflectance were measured using spectroscopy both in situ and under laboratory conditions. Their respective endmembers were extracted from ASTER imagery using the Pixel Purity Index (PPI). The endmembers were validated with in situ and laboratory thicket and bare-soil reflectance signatures. The spectral unmixing technique was applied to ASTER imagery to discriminate pure pixels of thicket vegetation and bare-soils; a residual spectral image was produced. The Residual Spectral Unmixing (RSU) procedure was applied to the residual spectral image to produce an RSU soil spectrum image. Partial Least Squares Regression (PSLR) model was developed using spectral signatures of a residual soil spectrum image as the independent variable and SOC concentration measured from soil samples as the dependent variable. The PSLR prediction model was used to predict SOC concentration on the RSU soil spectral image. The predicted SOC concentration was then validated with SOC concentration measured from the field plots. A Strong correlation (R2 = 0.82) was obtained between the predicted SOC concentration and the SOC concentration measured from field samples. The PSLR was then used to generate a map of SOC concentration for the Great Fish River Nature Reserve and its environs. Areas with very low SOC concentrations were found in the degraded communal villages, as opposed to the higher SOC values in the protected area. The results confirmed that RS techniques are key to estimating and mapping the spatial distribution of SOC concentration in partial subtropical thicket vegetation. Partial thicket vegetation has a huge influence on the soil spectra; it can influence the prediction of SOC concentration. The use of the RSU approach eliminates partial thicket vegetation cover from bare soil spectra. The residual soil spectrum image contains enough information for the mapping of SOC concentration. The technique has the potential to augment the applicability of airborne imaging spectroscopy for soil studies in the sub-tropical thicket biome and similar environments.
- Full Text:
- Date Issued: 2013
- Authors: Nyamugama, Adolph
- Date: 2013
- Subjects: Fragmented landscapes -- South Africa -- Eastern Cape -- Remote sensing , Environmental degradation -- South Africa -- Eastern Cape , Remote sensing , Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10672 , http://hdl.handle.net/10948/d1020303
- Description: The subtropical thicket biome in the Eastern Cape Province of South Africa has been heavily degraded and transformed due overutilization during the last century. The highly degraded and transformed areas exhibit a significant loss of above ground carbon stocks (AGC) and loss of SOC content. Information about land use /cover change and fragmentation dynamics is a prerequisite for measuring carbon stock changes. The main aim of this study is to assess the trends of land use/cover change, fragmentation dynamics, model the temporal changes of AGC stocks in the Great Fish River Nature Reserve and its environs from 1972 to 2010, quantify and map the spatial distribution of SOC concentrations in the partial subtropical thicket cover in the Great Fish River Nature Reserve and environs (communal rangelands). Multi-temporal analyses based on 1972 Landsat MSS, 1982 and 1992 Landsat TM, 2002 Landsat ETM and 2010 SPOT 5 High Resolution images were used for land use/cover change detection and fragmentation analysis. Object oriented post-classification comparison was applied for land use/cover change detection analysis. Fragmentation dynamics analysis was carried out by computing and analyzing landscape metrics in land use/cover classes. Landscape fragmentation analyses revealed that thicket vegetation has increasingly become fragmented, characterized by smaller less linked patches of intact thicket cover. Landscape metrics for intact thicket and degraded thicket classes reflected fragmentation, as illustrated by the increase in the Number of Patches (NP), Patch Density (PD), Landscape Shape Index (LSI), and a decrease in Mean Patch Size (MPS). The use of remote sensing techniques and landscape metrics was vital for the understanding of the dynamics of land use/cover change and fragmentation. Baseline land use/cover maps produced for 1972, 1982, 1992 2002 and 2010 and fragmentation analyses were then used for analyzing carbon stock changes in the study area. To model the temporal changes of AGC stocks in the Great Fish River Nature Reserve and its environs from 1972 to 2010, a method based on the integration of RS and GIS was employed for the estimation of AGC stocks in a time series. A non-linear regression model was developed using NDVI values generated from SPOT 5 HRG satellite imagery of 2010 as the independent variable and AGC stock estimates from field plots as the dependent variable. The regression model was used to estimate AGC stocks for the entire study area on the 2010 SPOT 5 HRG and also extrapolated to the 1972 Landsat MSS, 1982 and 1992 Landsat TM, and 2002 Landsat ETM. The AGC stocks for the period 1972 -1982, 1982-1992, 1992-200) and 2002-2010 were compared by means of change detection analysis. The comparison of AGC stocks was carried out at subtropical thicket class level. The results showed a decline of AGC stocks in all the classes from 1972 to 2010. Degraded and transformed thicket classes had the highest AGC stock losses. The decline of AGC stocks was attributed to thicket transformation and degradation which were caused by anthropogenic activities. To map and quantify SOC concentration in partial (fractional) thicket vegetation cover, the spectral reflectance of both thicket vegetation and bare-soils was measured in situ. Soil samples were collected from the sampling sites and transported to the laboratory for spectral reflectance and SOC measurements. Thicket vegetation and bare soil reflectance were measured using spectroscopy both in situ and under laboratory conditions. Their respective endmembers were extracted from ASTER imagery using the Pixel Purity Index (PPI). The endmembers were validated with in situ and laboratory thicket and bare-soil reflectance signatures. The spectral unmixing technique was applied to ASTER imagery to discriminate pure pixels of thicket vegetation and bare-soils; a residual spectral image was produced. The Residual Spectral Unmixing (RSU) procedure was applied to the residual spectral image to produce an RSU soil spectrum image. Partial Least Squares Regression (PSLR) model was developed using spectral signatures of a residual soil spectrum image as the independent variable and SOC concentration measured from soil samples as the dependent variable. The PSLR prediction model was used to predict SOC concentration on the RSU soil spectral image. The predicted SOC concentration was then validated with SOC concentration measured from the field plots. A Strong correlation (R2 = 0.82) was obtained between the predicted SOC concentration and the SOC concentration measured from field samples. The PSLR was then used to generate a map of SOC concentration for the Great Fish River Nature Reserve and its environs. Areas with very low SOC concentrations were found in the degraded communal villages, as opposed to the higher SOC values in the protected area. The results confirmed that RS techniques are key to estimating and mapping the spatial distribution of SOC concentration in partial subtropical thicket vegetation. Partial thicket vegetation has a huge influence on the soil spectra; it can influence the prediction of SOC concentration. The use of the RSU approach eliminates partial thicket vegetation cover from bare soil spectra. The residual soil spectrum image contains enough information for the mapping of SOC concentration. The technique has the potential to augment the applicability of airborne imaging spectroscopy for soil studies in the sub-tropical thicket biome and similar environments.
- Full Text:
- Date Issued: 2013
Nonlinear effects with a focus on cross phase modulation and its impact on wavelength division multiplexing optical fibre networks
- Gamatham, Romeo Reginald Gunther
- Authors: Gamatham, Romeo Reginald Gunther
- Date: 2013
- Subjects: Wavelength division multiplexing , Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6302 , vital:21071
- Description: The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario.
- Full Text:
- Date Issued: 2013
- Authors: Gamatham, Romeo Reginald Gunther
- Date: 2013
- Subjects: Wavelength division multiplexing , Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6302 , vital:21071
- Description: The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario.
- Full Text:
- Date Issued: 2013
Novel applications of Morita-Baylis-Hillman methodology in organic synthesis
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
- Date Issued: 2013
- Authors: Mciteka, Lulama Patrick
- Date: 2013 , 2013-04-22
- Subjects: Organic compounds -- Synthesis -- Research Asymmetric synthesis Asymmetry (Chemistry) Chemical reactions -- Research Camphor -- Research AZT (Drug) -- Research Chemical inhibitors -- Research Chemistry -- Methodology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4439 , http://hdl.handle.net/10962/d1007598
- Description: The overall approach in the present investigation has been to explore applications of the Morita-Baylis-Hillman (MBH) reaction in asymmetric synthesis and in the continuation of systems with medicinal potential. To this end, a series of varied camphor-derived acrylate esters was prepared to serve as chiral substrates in asymmetric Morita-Baylis- Hillman reactions. Reduction of N-substituted camphor-10-sulfonamides afforded the 3- exo-hydroxy derivatives as the major products. Acylation of the corresponding sodium alkoxides gave the desired 3-exo-acrylate esters, isolation of which was complicated by concomitant formation of hydrochlorinated and diastereomeric competition products. Bulky camphorsulfonamides containing alkyl, dialkyl, aromatic and adamantyl groups were selected as N-substituents with the view of achieving stereoselective outcome in subsequent MBH reactions. The synthesis of novel camphor-derived Morita-Baylis-Hillman adducts using various pyridine-carboxaldehydes proceeded with exceptionally high yields with diastereoselectivities ranging from 7-33 % d.e. Both 1D and 2D NMR and HRMS techniques were employed to confirm the structures and an extensive study of the electropositive fragmentation patterns of a number of camphor-derived chiral acrylate esters was conducted. Attention has also been given to the application of MBH methodology in the construction of heterocyclic ‘cinnamate-like’ AZT conjugates which were designed to serve as dualaction HIV-1 integrase-reverse transcriptase (IN-RT) inhibitors. A number of pyridine carboxaldehyde-derived MBH adducts were synthesized using methyl, ethyl and t-butyl acrylates in the presence of 3-hydroxyquinuclidine (3-HQ) as catalyst. The yields for these reactions were excellent. The resulting MBH adducts were acetylated and subjected to aza-Michael addition using propargylamine. The resulting alkylamino compounds were then used in ‘Click reactions’ to form the targeted AZT-conjugates in moderate to excellent yield. In silico docking of computer modelled AZT-conjugates into the HIV-1 integrase and reverse transcriptase enzyme-active sites and potential hydrogen-bonding interaction with active-site amino acid residues were identified. The electrospray MS fragmentations of the AZT and the novel AZT-conjugates were also investigated and common fragmentation pathways were identified.
- Full Text:
- Date Issued: 2013
Numerical relativity on cosmological past null cones
- Van der Walt, Petrus Johannes
- Authors: Van der Walt, Petrus Johannes
- Date: 2013
- Subjects: Cosmology Numerical calculations General relativity (Physics) -- Mathematics Einstein field equations Gravity Gravitational waves Horizon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5396 , http://hdl.handle.net/10962/d1002959
- Description: The observational approach to cosmology is the endeavour to reconstruct the geometry of the Universe using only data that is theoretically verifiable within the causal boundaries of a cosmological observer. Using this approach, it was shown in [36] that given ideal cosmological observations, the only essential assumption necessary to determine the geometry of the Universe is a theory of gravity. Assuming General Relativity, the full set of Einstein field equations (EFEs) can be used to reconstruct the geometry of the Universe using direct observations on the past null cone (PNC) as initial conditions. Observationally and theoretically this is a very ambitious task and therefore, current developments have been restricted to spherically symmetric dust models while only relaxing the usual assumption of homogeneity in the radial direction. These restricted models are important for the development of theoretical foundations and also useful as verification models since they avoid the circularity of verifying what has already been assumed. The work presented in this thesis is the development of such a model where numerical relativity (NR) is used to simulate the observable universe. Similar to the work of Ellis and co-workers [36], a reference frame based on the PNC is used. The reference frame used here, however, is based on that of the characteristic formalism of NR, which has developed for calculating the propagation of gravitational waves. This provides a formalism that is well established in NR, making the use of existing algorithms possible. The Bondi-Sachs coordinates of the characteristic formalism is, however, not suitable for calculations beyond the observer apparent horizon (AH) since the diameter distance used as a radial coordinate becomes multi-valued when the cosmological PNC reconverges in the history of a universe, smaller in the past. With this taken into consideration, the Bondi-Sachs characteristic formalism is implemented for cosmology and the problem approaching the AH is investigated. Further developments address the limitations approaching the AH by introducing a metric based on the Bondi-Sachs metric where the radial coordinate is replaced with an affine parameter. The model is derived with a cosmological constant Λ incorporated into the EFEs where Λ is taken as a parameter of the theory of gravity rather than as a matter source term. Similar to the conventional characteristic formalism, this model consists of a system of differential equations for numerically evolving the EFEs as a characteristic initial value problem (CIVP). A numerical code implemented for the method has been found to be second order convergent. This code enables simulations of different models given identical data on the initial null cone and provides a method to investigate their physical consistency within the causally connected region of our current PNC. These developments closely follow existing 3D schemes developed for gravitational wave simulations, which should make it natural to extend the affine CIVP beyond spherical symmetric simulations. The developments presented in this thesis is an extended version of two papers published earlier.
- Full Text:
- Date Issued: 2013
- Authors: Van der Walt, Petrus Johannes
- Date: 2013
- Subjects: Cosmology Numerical calculations General relativity (Physics) -- Mathematics Einstein field equations Gravity Gravitational waves Horizon
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5396 , http://hdl.handle.net/10962/d1002959
- Description: The observational approach to cosmology is the endeavour to reconstruct the geometry of the Universe using only data that is theoretically verifiable within the causal boundaries of a cosmological observer. Using this approach, it was shown in [36] that given ideal cosmological observations, the only essential assumption necessary to determine the geometry of the Universe is a theory of gravity. Assuming General Relativity, the full set of Einstein field equations (EFEs) can be used to reconstruct the geometry of the Universe using direct observations on the past null cone (PNC) as initial conditions. Observationally and theoretically this is a very ambitious task and therefore, current developments have been restricted to spherically symmetric dust models while only relaxing the usual assumption of homogeneity in the radial direction. These restricted models are important for the development of theoretical foundations and also useful as verification models since they avoid the circularity of verifying what has already been assumed. The work presented in this thesis is the development of such a model where numerical relativity (NR) is used to simulate the observable universe. Similar to the work of Ellis and co-workers [36], a reference frame based on the PNC is used. The reference frame used here, however, is based on that of the characteristic formalism of NR, which has developed for calculating the propagation of gravitational waves. This provides a formalism that is well established in NR, making the use of existing algorithms possible. The Bondi-Sachs coordinates of the characteristic formalism is, however, not suitable for calculations beyond the observer apparent horizon (AH) since the diameter distance used as a radial coordinate becomes multi-valued when the cosmological PNC reconverges in the history of a universe, smaller in the past. With this taken into consideration, the Bondi-Sachs characteristic formalism is implemented for cosmology and the problem approaching the AH is investigated. Further developments address the limitations approaching the AH by introducing a metric based on the Bondi-Sachs metric where the radial coordinate is replaced with an affine parameter. The model is derived with a cosmological constant Λ incorporated into the EFEs where Λ is taken as a parameter of the theory of gravity rather than as a matter source term. Similar to the conventional characteristic formalism, this model consists of a system of differential equations for numerically evolving the EFEs as a characteristic initial value problem (CIVP). A numerical code implemented for the method has been found to be second order convergent. This code enables simulations of different models given identical data on the initial null cone and provides a method to investigate their physical consistency within the causally connected region of our current PNC. These developments closely follow existing 3D schemes developed for gravitational wave simulations, which should make it natural to extend the affine CIVP beyond spherical symmetric simulations. The developments presented in this thesis is an extended version of two papers published earlier.
- Full Text:
- Date Issued: 2013
On the implementation effectiveness and efficiency of ecological interventions in operational contexts : the case of Working for Water
- Authors: McConnachie, Matthew Morgan
- Date: 2013
- Subjects: Working for Water Programme Alien plants -- South Africa -- Eastern Cape Alien plants -- Control -- South Africa -- Eastern Cape Alien plants -- Control -- Cost effectiveness -- South Africa -- Eastern Cape Conservation of natural resources -- South Africa -- Eastern Cape Acacia mearnsii -- South Africa -- Eastern Cape Poverty -- South Africa -- Eastern Cape Revegetation -- South Africa -- Eastern Cape Restoration ecology -- South Africa -- Eastern Cape Environmental degradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4729 , http://hdl.handle.net/10962/d1001956
- Description: There is little understanding of the implementation efficiency and effectiveness of restoring plant invaded landscapes within operational contexts. South Africa's Working for Water (WfW) programme is arguably the most ambitious alien plant control programme in the world, yet little is known about its cost-effectiveness and the challenges it faces in linking poverty and environmental objectives. My first aim was to assess the cost-effectiveness of invasive plant removal, and the factors that underpin its effectiveness over large spatial and temporal scales. The second aim was to compare the accuracy of evidence-based findings with managers' experience-based beliefs, and to assess whether managers are willing to change their beliefs after being exposed to it. The third aim was to assess the costs and benefits of removal versus removal followed by active native re-vegetation. My final aim is to assess the challenges and lessons learnt by managers linking ecological restoration with poverty alleviation objectives, specifically within the public works model. My study area was focused primarily on two WfW river catchment projects in the western region of the Eastern Cape province. I adopted an interdisciplinary approach drawing from a range of methods such as observational studies, statistical modelling and interviews with managers. The key findings were that control efforts in the two catchment projects are largely inadequate owing to many sites being re-invaded and not enough resources being allocated to the catchments. It would take between 54 and 695 years to clear the respective catchments. In terms of cost-effectiveness, my results exceeded previous estimates by 1.5 to 8.6 times for each catchment project. After being exposed to the evidence-based findings, the managers did not change their beliefs when it came to forecasting the future effectiveness. I found that active native re-vegetation after removal of invasive plants is very costly and that priority should be given to understanding the effectiveness of the removal treatments on native species recovery. The managers cited significant challenges in effectively and efficiently meeting the programmes dual objectives. Based on a broader review of the public works literature I recommend WfW re-examine the type of public works they currently use.
- Full Text:
- Date Issued: 2013
- Authors: McConnachie, Matthew Morgan
- Date: 2013
- Subjects: Working for Water Programme Alien plants -- South Africa -- Eastern Cape Alien plants -- Control -- South Africa -- Eastern Cape Alien plants -- Control -- Cost effectiveness -- South Africa -- Eastern Cape Conservation of natural resources -- South Africa -- Eastern Cape Acacia mearnsii -- South Africa -- Eastern Cape Poverty -- South Africa -- Eastern Cape Revegetation -- South Africa -- Eastern Cape Restoration ecology -- South Africa -- Eastern Cape Environmental degradation -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4729 , http://hdl.handle.net/10962/d1001956
- Description: There is little understanding of the implementation efficiency and effectiveness of restoring plant invaded landscapes within operational contexts. South Africa's Working for Water (WfW) programme is arguably the most ambitious alien plant control programme in the world, yet little is known about its cost-effectiveness and the challenges it faces in linking poverty and environmental objectives. My first aim was to assess the cost-effectiveness of invasive plant removal, and the factors that underpin its effectiveness over large spatial and temporal scales. The second aim was to compare the accuracy of evidence-based findings with managers' experience-based beliefs, and to assess whether managers are willing to change their beliefs after being exposed to it. The third aim was to assess the costs and benefits of removal versus removal followed by active native re-vegetation. My final aim is to assess the challenges and lessons learnt by managers linking ecological restoration with poverty alleviation objectives, specifically within the public works model. My study area was focused primarily on two WfW river catchment projects in the western region of the Eastern Cape province. I adopted an interdisciplinary approach drawing from a range of methods such as observational studies, statistical modelling and interviews with managers. The key findings were that control efforts in the two catchment projects are largely inadequate owing to many sites being re-invaded and not enough resources being allocated to the catchments. It would take between 54 and 695 years to clear the respective catchments. In terms of cost-effectiveness, my results exceeded previous estimates by 1.5 to 8.6 times for each catchment project. After being exposed to the evidence-based findings, the managers did not change their beliefs when it came to forecasting the future effectiveness. I found that active native re-vegetation after removal of invasive plants is very costly and that priority should be given to understanding the effectiveness of the removal treatments on native species recovery. The managers cited significant challenges in effectively and efficiently meeting the programmes dual objectives. Based on a broader review of the public works literature I recommend WfW re-examine the type of public works they currently use.
- Full Text:
- Date Issued: 2013
Pedagogical ways-of-knowing in the design studio
- Authors: Kethro, Philippa
- Date: 2013
- Subjects: Graphic arts -- Education (Higher) Interior decoration -- Education (Higher) Fashion design -- Education (Higher) Industrial design -- Education (Higher) Aesthetics, Modern Art -- Philosophy Education, Higher -- Aims and objectives Interaction analysis in education Visual literacy Critical realism Communication and education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1840 , http://hdl.handle.net/10962/d1004338
- Description: This research addresses the effect of pedagogical ways-of-knowing in higher education design programmes such as Graphic Design, Interior Design, Fashion, and Industrial Design. One problematic aspect of design studio pedagogy is communication between teachers and students about the aesthetic visual meaning of the students’ designed objects. This problematic issue involves ambiguous and divergent ways-of-knowing the design meaning of these objects. The research focus is on the design teacher role in design studio interactions, and regards pedagogical ways-of-knowing as the ways in which teachers expect students to know visual design meaning. This pedagogical issue is complicated by the fact that there is no agreed-upon corpus of domain knowledge in design, so visual meaning depends greatly on the social knowledge retained by students and teachers. The thesis pursues an explanation of pedagogical ways-of-knowing that is approached through the philosophy of critical realism. How it is that particular events and experiences come to occur in a particular way is the general focus of critical realist philosophy. A critical realist approach to explanation is the use of abductive inference, or inference as to how it is that puzzling empirical circumstances emerge. An abductive strategy aims to explain how such circumstances emerge by considering them in a new light. This is done in this study by applying Luhmann’s theory of the emergence of cognition in communication to teacher ways-of-knowing in the design studio. Through the substantive use of Luhmann’s theory, an abductive conjecture of pedagogical ways-of-knowing is mounted. This conjecture is brought to bear on an examination of research data, in order to explain how pedagogical ways of-knowing constrain or enable the emergence of shared visual design meaning in the design studio. The abductive analysis explains three design pedagogical ways-of-knowing: design inquiry, design representation and design intent. These operate as macro relational mechanisms that either enable or constrain the emergence of shared visual design meaning in the design studio. The mechanism of relation is between design inquiry, design representation and design intent as historical knowing structures, and ways-of-knowing in respect of each of these knowing structures. For example, design inquiry as an historical knowing structure has over time moved from ways-of-knowing such as rationalistic problem solving to direct social observation and later to interpretive cultural analysis. The antecedence of these ways-of-knowing is important because communication about visual meaning depends upon prior knowledge, and teachers may then reproduce past ways-of-knowing. The many ways-of-knowing that respectively relate to design inquiry, design representation and design intent are shown to be communicatively formed and recursive over time. From a Luhmannian perspective, these ways-of-knowing operate as variational distinctions that indicate or relate to the knowing structures of design inquiry, design representation and design intent. This is the micro-level operation of pedagogical ways-of-knowing as relational mechanisms in design studio communication. Design teachers’ own ways-of-knowing may then embrace implicit way-of-knowing distinctions that indicate the knowledge structures of design inquiry, design representation and design intent. This implicit indication by distinction is the relational mechanism that may bring design teachers’ expectation that this and not that visual design meaning should apply in communication about any student’s designed object. Such an expectation influences communication between teachers and students about the potential future meaning of students’ designs. Consequently, shared visual design meaning may or may not emerge. The research explanation brings the opportunity for design teachers to make explicit the often implicit way-of-knowing distinctions they use, and to relate these distinctions to the knowing structures thus indicated. The study then offers a new perspective on the old design pedagogical problem of design studio conflict over the meaning of students’ designs. Options for applying this research explanation in design studio interactions between students and teachers are therefore suggested.
- Full Text:
- Date Issued: 2013
- Authors: Kethro, Philippa
- Date: 2013
- Subjects: Graphic arts -- Education (Higher) Interior decoration -- Education (Higher) Fashion design -- Education (Higher) Industrial design -- Education (Higher) Aesthetics, Modern Art -- Philosophy Education, Higher -- Aims and objectives Interaction analysis in education Visual literacy Critical realism Communication and education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1840 , http://hdl.handle.net/10962/d1004338
- Description: This research addresses the effect of pedagogical ways-of-knowing in higher education design programmes such as Graphic Design, Interior Design, Fashion, and Industrial Design. One problematic aspect of design studio pedagogy is communication between teachers and students about the aesthetic visual meaning of the students’ designed objects. This problematic issue involves ambiguous and divergent ways-of-knowing the design meaning of these objects. The research focus is on the design teacher role in design studio interactions, and regards pedagogical ways-of-knowing as the ways in which teachers expect students to know visual design meaning. This pedagogical issue is complicated by the fact that there is no agreed-upon corpus of domain knowledge in design, so visual meaning depends greatly on the social knowledge retained by students and teachers. The thesis pursues an explanation of pedagogical ways-of-knowing that is approached through the philosophy of critical realism. How it is that particular events and experiences come to occur in a particular way is the general focus of critical realist philosophy. A critical realist approach to explanation is the use of abductive inference, or inference as to how it is that puzzling empirical circumstances emerge. An abductive strategy aims to explain how such circumstances emerge by considering them in a new light. This is done in this study by applying Luhmann’s theory of the emergence of cognition in communication to teacher ways-of-knowing in the design studio. Through the substantive use of Luhmann’s theory, an abductive conjecture of pedagogical ways-of-knowing is mounted. This conjecture is brought to bear on an examination of research data, in order to explain how pedagogical ways of-knowing constrain or enable the emergence of shared visual design meaning in the design studio. The abductive analysis explains three design pedagogical ways-of-knowing: design inquiry, design representation and design intent. These operate as macro relational mechanisms that either enable or constrain the emergence of shared visual design meaning in the design studio. The mechanism of relation is between design inquiry, design representation and design intent as historical knowing structures, and ways-of-knowing in respect of each of these knowing structures. For example, design inquiry as an historical knowing structure has over time moved from ways-of-knowing such as rationalistic problem solving to direct social observation and later to interpretive cultural analysis. The antecedence of these ways-of-knowing is important because communication about visual meaning depends upon prior knowledge, and teachers may then reproduce past ways-of-knowing. The many ways-of-knowing that respectively relate to design inquiry, design representation and design intent are shown to be communicatively formed and recursive over time. From a Luhmannian perspective, these ways-of-knowing operate as variational distinctions that indicate or relate to the knowing structures of design inquiry, design representation and design intent. This is the micro-level operation of pedagogical ways-of-knowing as relational mechanisms in design studio communication. Design teachers’ own ways-of-knowing may then embrace implicit way-of-knowing distinctions that indicate the knowledge structures of design inquiry, design representation and design intent. This implicit indication by distinction is the relational mechanism that may bring design teachers’ expectation that this and not that visual design meaning should apply in communication about any student’s designed object. Such an expectation influences communication between teachers and students about the potential future meaning of students’ designs. Consequently, shared visual design meaning may or may not emerge. The research explanation brings the opportunity for design teachers to make explicit the often implicit way-of-knowing distinctions they use, and to relate these distinctions to the knowing structures thus indicated. The study then offers a new perspective on the old design pedagogical problem of design studio conflict over the meaning of students’ designs. Options for applying this research explanation in design studio interactions between students and teachers are therefore suggested.
- Full Text:
- Date Issued: 2013
Petrogenesis and metallogenesis of the Panzhihua Fe-Ti oxide ore-bearing mafic layered intrusion, SW China
- Authors: Howarth, Geoffrey Hamilton
- Date: 2013
- Subjects: Petrogenesis Metallogeny Intrusions (Geology) -- China -- Panzhihua Metallogenic provinces -- China -- Panzhihua Igneous rocks -- China -- Panzhihua Geochemistry Iron Titanium Oxides Ores Magmas
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4915 , http://hdl.handle.net/10962/d1001810
- Description: The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.
- Full Text:
- Date Issued: 2013
- Authors: Howarth, Geoffrey Hamilton
- Date: 2013
- Subjects: Petrogenesis Metallogeny Intrusions (Geology) -- China -- Panzhihua Metallogenic provinces -- China -- Panzhihua Igneous rocks -- China -- Panzhihua Geochemistry Iron Titanium Oxides Ores Magmas
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4915 , http://hdl.handle.net/10962/d1001810
- Description: The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.
- Full Text:
- Date Issued: 2013
Phototransformation of pollutants using lutetium and zinc phthalocyanines anchored on electrospun polymer fibers
- Authors: Zugle, Ruphino
- Date: 2013
- Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
- Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
- Full Text:
- Date Issued: 2013
- Authors: Zugle, Ruphino
- Date: 2013
- Subjects: Electrospinning Phthalocyanines Lutetium Zinc Polymers Dysprosium Pollutants Air Pollution Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4286 , http://hdl.handle.net/10962/d1002962
- Description: Novel lanthanide phthalocyanines containing dysprosium, erbium and lutetium as central metals were synthesized using phthalonitrile:metal salt ratio of 4:1 or lower phthalonitrile content as well as using unmetallated phthalocyanine. They were characterized using various spectroscopic and elemental analyses. Dysprosium bis-phthalocyanine was obtained while monomers were obtained for erbium and lutetium phthalocyanines. Theopen-shelldysprosiumbis-phthalocyanine and the monomeric complex of the open-shell erbium were neither fluorescent nor showed the ability to generate singlet oxygen. The triplet states of all the lutetium phthalocyanines were found to be populated with high triplet quantum yields and corresponding high singlet oxygen quantum yields. The fluorescence quantum yields of the lutetium phthalocyanines were however found to be very low. The lutetium phthalocyanines together with unsubstituted zinc phthalocyanine and its derivatives were successfully incorporated into electrospun polymer fibers either by covalent linkage or sorption forces. Spectral characteristics of the functionalized electrospun polymer fibers indicated that the phthalocyanines were bound and their integrity maintained within the fiber matrices. Most importantly the fluorescence and photoactivity of the phthalocyanines were equally maintained within the electrospun fibers. The functionalized electrospun polymer fibers especially those containing the zinc phthalocyanines could qualitatively detect nitrogen dioxide, a known environmental air pollutant. Also all the functionalized electrospun polystyrene and polysulfone fibers containing lutetium and zinc phthalocyanines could be applied for the photoconversion of 4-chlorophenol, 4-nitrophenol and methyl orange. Those of polystyrene could be re-used. Polyacrylic acid and polyurethane functionalized electrospun fibers were found not to be suitable for photocatalytic applications in aqueous medium. 4-Chlorophenol was found to be more susceptible to photodegradation while methyl orange very difficult to degrade.
- Full Text:
- Date Issued: 2013
Politics, polemics and practice: a history of narratives about, and responses to, AIDS in South Africa, 1980-1995
- Authors: Tsampiras, Carla
- Date: 2013
- Subjects: AIDS (Disease) -- Government policy -- South Africa AIDS (Disease) -- Political aspects -- South Africa -- History AIDS (Disease) -- South Africa -- Public opinion -- History AIDS (Disease) -- Social aspects -- South Africa -- History South Africa -- Politics and government -- 20th century African National Congress Health Policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2517 , http://hdl.handle.net/10962/d1001653
- Description: The ongoing urgency of addressing AIDS in South Africa has kept academics and activists focussed primarily on the immediate crises of AIDS ‘in the present’. This thesis, covering the period 1980 – 1995, examines narratives about, and responses to, AIDS ‘in the past’ and explores the interplay between these narratives and elites in medical and political communities trying to address AIDS during a period of political transition. The thesis begins by examining the hegemonic medico-scientific narratives about AIDS that featured in the South African Medical Journal, an important site of enquiry as AIDS was primarily conceived of as a ‘medical issue’. The SAMJ narratives, which often relied on constructed ‘AIDS avatars’, framed understandings of the syndrome and influenced responses to it by medical and political communities. The first community that the thesis explores is the African National Congress (ANC) in exile, which had to address AIDS in exile communities and prepare health strategies for ‘the new South Africa’. Secondly, the thesis analyses government responses to AIDS and argues that four phases of response can be identified. These phases were characterised by minimum concerns about obtaining information and providing health advice; efforts to gather infection data while exploiting political and public fear; attempts to extend health education and (belatedly) encourage broader engagement; and finally, consultative, democratic ideals. The thesis then examines the National Medical and Dental Association (NAMDA) a progressive medical organisation that worked with the ANC on influential health (and AIDS) strategies. NAMDA members ‘crossed over’ between various medical and political communities and both reinforced and challenged hegemonic AIDS narratives. Finally, the thesis moves from the abstract, via the practical, to the personal and concludes with a detailed account of the experiences of two sexuality activists at the intersections of these communities and narratives. By focussing on these medical and political communities, and analysing the relationships between these communities, the existing AIDS narratives, and individuals, the thesis also reveals the constructions of morality, ‘race’, gender, and sexuality that infused them. In doing this it shows how polemic and politics combined to influence practical responses to, and personal experiences of, AIDS.
- Full Text:
- Date Issued: 2013
- Authors: Tsampiras, Carla
- Date: 2013
- Subjects: AIDS (Disease) -- Government policy -- South Africa AIDS (Disease) -- Political aspects -- South Africa -- History AIDS (Disease) -- South Africa -- Public opinion -- History AIDS (Disease) -- Social aspects -- South Africa -- History South Africa -- Politics and government -- 20th century African National Congress Health Policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2517 , http://hdl.handle.net/10962/d1001653
- Description: The ongoing urgency of addressing AIDS in South Africa has kept academics and activists focussed primarily on the immediate crises of AIDS ‘in the present’. This thesis, covering the period 1980 – 1995, examines narratives about, and responses to, AIDS ‘in the past’ and explores the interplay between these narratives and elites in medical and political communities trying to address AIDS during a period of political transition. The thesis begins by examining the hegemonic medico-scientific narratives about AIDS that featured in the South African Medical Journal, an important site of enquiry as AIDS was primarily conceived of as a ‘medical issue’. The SAMJ narratives, which often relied on constructed ‘AIDS avatars’, framed understandings of the syndrome and influenced responses to it by medical and political communities. The first community that the thesis explores is the African National Congress (ANC) in exile, which had to address AIDS in exile communities and prepare health strategies for ‘the new South Africa’. Secondly, the thesis analyses government responses to AIDS and argues that four phases of response can be identified. These phases were characterised by minimum concerns about obtaining information and providing health advice; efforts to gather infection data while exploiting political and public fear; attempts to extend health education and (belatedly) encourage broader engagement; and finally, consultative, democratic ideals. The thesis then examines the National Medical and Dental Association (NAMDA) a progressive medical organisation that worked with the ANC on influential health (and AIDS) strategies. NAMDA members ‘crossed over’ between various medical and political communities and both reinforced and challenged hegemonic AIDS narratives. Finally, the thesis moves from the abstract, via the practical, to the personal and concludes with a detailed account of the experiences of two sexuality activists at the intersections of these communities and narratives. By focussing on these medical and political communities, and analysing the relationships between these communities, the existing AIDS narratives, and individuals, the thesis also reveals the constructions of morality, ‘race’, gender, and sexuality that infused them. In doing this it shows how polemic and politics combined to influence practical responses to, and personal experiences of, AIDS.
- Full Text:
- Date Issued: 2013
Polymer based electrospun nanofibers as diagnostic probes for the detection of toxic metal ions in water
- Authors: Ondigo, Dezzline Adhiambo
- Date: 2013
- Subjects: Heavy metals , Nanofibers , Nanoparticles , Colorimetric analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4557 , http://hdl.handle.net/10962/d1018261
- Description: The thesis presents the development of polymer based electrospun nanofibers as diagnostic probes for the selective detection of toxic metal ions in water. Through modification of the chemical characteristics of nanofibers by pre- and post-electrospinning treatments, three different diagnostic probes were successfully developed. These were the fluorescent pyridylazo-2-naphthol-poly(acrylic acid) nanofiber probe, the colorimetric probe based on glutathione-stabilized silver/copper alloy nanoparticles and the colorimetric probe based on 2-(2’-Pyridyl)-imidazole functionalized nanofibers. The probes were characterized by Fourier transform infrared spectroscopy (FTIR), Energy dispersive x-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The fluorescent nanofiber probe was developed towards the determination of Ni²⁺. Covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymeric nanofibers were employed. The solid state Ni²⁺ probe exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 mg/mL based on the Stern-Volmer mechanism. The detection limit of the nanofiber probe was found to be 0.07 ng/mL. The versatility of the fluorescent probe was demonstrated by affording a simple, rapid and selective detection of Ni²⁺ in the presence of other competing metal ions by direct analysis without employing any sample handling steps. For the second part of the study, a simple strategy based on the in-situ synthesis of the glutathione stabilized silver/copper alloy nanoparticles (Ag/Cu alloy NPs) in nylon 6 provided a fast procedure for fabricating a colorimetric probe for the detection of Ni²⁺ in water samples. The electrospun nanofiber composites responded to Ni²⁺ ions but did not suffer any interference from the other metal ions. The effect of Ni²⁺ concentration on the nanocomposite fibers was considered and the “eye-ball” limit of detection was found to be 5.8 μg/mL. Lastly, the third probe was developed by covalently linking an imidazole derivative; 2-(2′-Pyridyl)-imidazole (PIMH) to Poly(vinylbenzyl chloride) (PVBC) and nylon 6 nanofibers by post-electrospinning treatments using a wet chemical method and graft copolymerization technique, respectively. The post-electrospinning modifications of the nanofibers were achieved without altering their fibrous morphology. The color change to red-orange in the presence of Fe²⁺ for both the grafted nylon 6 (white) and the chemically modified PVBC (yellow) nanofibers was instantaneous. The developed diagnostic probes exhibited the desired selectivity towards the targeted metal ions.
- Full Text:
- Date Issued: 2013
- Authors: Ondigo, Dezzline Adhiambo
- Date: 2013
- Subjects: Heavy metals , Nanofibers , Nanoparticles , Colorimetric analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4557 , http://hdl.handle.net/10962/d1018261
- Description: The thesis presents the development of polymer based electrospun nanofibers as diagnostic probes for the selective detection of toxic metal ions in water. Through modification of the chemical characteristics of nanofibers by pre- and post-electrospinning treatments, three different diagnostic probes were successfully developed. These were the fluorescent pyridylazo-2-naphthol-poly(acrylic acid) nanofiber probe, the colorimetric probe based on glutathione-stabilized silver/copper alloy nanoparticles and the colorimetric probe based on 2-(2’-Pyridyl)-imidazole functionalized nanofibers. The probes were characterized by Fourier transform infrared spectroscopy (FTIR), Energy dispersive x-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The fluorescent nanofiber probe was developed towards the determination of Ni²⁺. Covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymeric nanofibers were employed. The solid state Ni²⁺ probe exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 mg/mL based on the Stern-Volmer mechanism. The detection limit of the nanofiber probe was found to be 0.07 ng/mL. The versatility of the fluorescent probe was demonstrated by affording a simple, rapid and selective detection of Ni²⁺ in the presence of other competing metal ions by direct analysis without employing any sample handling steps. For the second part of the study, a simple strategy based on the in-situ synthesis of the glutathione stabilized silver/copper alloy nanoparticles (Ag/Cu alloy NPs) in nylon 6 provided a fast procedure for fabricating a colorimetric probe for the detection of Ni²⁺ in water samples. The electrospun nanofiber composites responded to Ni²⁺ ions but did not suffer any interference from the other metal ions. The effect of Ni²⁺ concentration on the nanocomposite fibers was considered and the “eye-ball” limit of detection was found to be 5.8 μg/mL. Lastly, the third probe was developed by covalently linking an imidazole derivative; 2-(2′-Pyridyl)-imidazole (PIMH) to Poly(vinylbenzyl chloride) (PVBC) and nylon 6 nanofibers by post-electrospinning treatments using a wet chemical method and graft copolymerization technique, respectively. The post-electrospinning modifications of the nanofibers were achieved without altering their fibrous morphology. The color change to red-orange in the presence of Fe²⁺ for both the grafted nylon 6 (white) and the chemically modified PVBC (yellow) nanofibers was instantaneous. The developed diagnostic probes exhibited the desired selectivity towards the targeted metal ions.
- Full Text:
- Date Issued: 2013
Positions on the mat : a micro-ethnographic study of teachers' and learners' co-construction of an early literacy practice
- Authors: Van der Mescht, Caroline
- Date: 2013 , 2013-06-10
- Subjects: Literacy -- Study and teaching (Primary) -- South Africa -- Eastern Cape English language -- Study and teaching (Primary) -- South Africa -- Eastern Cape English literature -- Study and teaching (Primary) -- South Africa -- Eastern Cape Education, Primary -- Research -- South Africa -- Eastern Cape Teachers -- Psychology Language and culture
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1836 , http://hdl.handle.net/10962/d1004333
- Description: Thesis embargoed until end of 2023. , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Van der Mescht, Caroline
- Date: 2013 , 2013-06-10
- Subjects: Literacy -- Study and teaching (Primary) -- South Africa -- Eastern Cape English language -- Study and teaching (Primary) -- South Africa -- Eastern Cape English literature -- Study and teaching (Primary) -- South Africa -- Eastern Cape Education, Primary -- Research -- South Africa -- Eastern Cape Teachers -- Psychology Language and culture
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1836 , http://hdl.handle.net/10962/d1004333
- Description: Thesis embargoed until end of 2023. , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Postcolonial monuments and public sculpture in Zimbabwe
- Authors: Samwanda, Biggie
- Date: 2013 , 2013-10-10
- Subjects: Benhura, Dominic, 1968- -- Criticism and interpretation Madebe, Adam -- Criticism and interpretation Postcolonialism and the arts Monuments -- Zimbabwe Public sculpture -- Zimbabwe Art -- Political aspects -- Zimbabwe Collective memory in art -- Zimbabwe Old Bulawayo (Zimbabwe) National Heroes Acre (Zimbabwe)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2447 , http://hdl.handle.net/10962/d1006825
- Description: The study critically examines public art in postcolonial Zimbabwe‘s cities of Harare and Bulawayo. In a case by case approach, I analyse the National Heroes Acre and Old Bulawayo monuments, and three contemporary sculptures – Dominic Benhura‘s Leapfrog (1993) and Adam Madebe‘s Ploughman (1987) and Looking into the future (1985). I used a qualitative research methodology to collect and analyse data. My research design utilised in-depth interviews, observation, content and document analysis, and photography to gather nuanced data and these methods ensured that data collected is validated and/or triangulated. I argue that in Zimbabwe, monuments and public sculpture serve as the necessary interface of the visual, cultural and political discourse of a postcolonial nation that is constantly in transition and dialogue with the everyday realities of trying to understand and construct a national identity from a nest of sub-cultures. I further argue that monuments and public sculpture in Zimbabwe abound with political imperatives given that, as visual artefacts that interlace with ritual performance, they are conscious creations of society and are therefore constitutive of that society‘s heritage and social memory. Since independence in 1980, monuments and public sculpture have helped to open up discursive space and dialogue on national issues and myths. Such discursive spaces and dialogues, I also argue, have been particularly animated from the late 1990s to the present, a period in which the nation has engaged in self-introspection in the face of socio-political change and challenges in the continual process of imagining the Zimbabwean nation. Little research focusing on postcolonial public art in Zimbabwe has hitherto been undertaken. This study addresses gaps in this literature while also providing a spring board from which future studies may emerge. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Samwanda, Biggie
- Date: 2013 , 2013-10-10
- Subjects: Benhura, Dominic, 1968- -- Criticism and interpretation Madebe, Adam -- Criticism and interpretation Postcolonialism and the arts Monuments -- Zimbabwe Public sculpture -- Zimbabwe Art -- Political aspects -- Zimbabwe Collective memory in art -- Zimbabwe Old Bulawayo (Zimbabwe) National Heroes Acre (Zimbabwe)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2447 , http://hdl.handle.net/10962/d1006825
- Description: The study critically examines public art in postcolonial Zimbabwe‘s cities of Harare and Bulawayo. In a case by case approach, I analyse the National Heroes Acre and Old Bulawayo monuments, and three contemporary sculptures – Dominic Benhura‘s Leapfrog (1993) and Adam Madebe‘s Ploughman (1987) and Looking into the future (1985). I used a qualitative research methodology to collect and analyse data. My research design utilised in-depth interviews, observation, content and document analysis, and photography to gather nuanced data and these methods ensured that data collected is validated and/or triangulated. I argue that in Zimbabwe, monuments and public sculpture serve as the necessary interface of the visual, cultural and political discourse of a postcolonial nation that is constantly in transition and dialogue with the everyday realities of trying to understand and construct a national identity from a nest of sub-cultures. I further argue that monuments and public sculpture in Zimbabwe abound with political imperatives given that, as visual artefacts that interlace with ritual performance, they are conscious creations of society and are therefore constitutive of that society‘s heritage and social memory. Since independence in 1980, monuments and public sculpture have helped to open up discursive space and dialogue on national issues and myths. Such discursive spaces and dialogues, I also argue, have been particularly animated from the late 1990s to the present, a period in which the nation has engaged in self-introspection in the face of socio-political change and challenges in the continual process of imagining the Zimbabwean nation. Little research focusing on postcolonial public art in Zimbabwe has hitherto been undertaken. This study addresses gaps in this literature while also providing a spring board from which future studies may emerge. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Representation and use of indigenous heritage constructs : implications for the quality and relevance of heritage education in post colonial southern Africa
- Authors: Zazu, Cryton
- Date: 2013
- Subjects: Albany Museum (Grahamstown, South Africa) Cultural property -- Conservation and restoration -- Research -- Africa, Southern Great Zimbabwe (Extinct city) Indigenous peoples -- Material culture -- Africa, Southern Anthropological museums and collections -- Management -- Research -- Africa, Southern Cultural property -- Management -- Research Ethnoscience -- Study and teaching -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1407 , http://hdl.handle.net/10962/d1002015
- Description: This study explores representation and use of indigenous heritage constructs with a view to identifying implications thereof for the quality and relevance of heritage education practices in post colonial southern Africa. Framed within a critical hermeneutic research paradigm under-laboured by critical realist ontology, the study was conducted using a multiple case study research design. The data collection protocol was three-phased, starting with a process of contextual profiling, within which insights were gained into discourses shaping the constitution and orientation of heritage education practices at the Albany Museum in South Africa, the Great Zimbabwe Monument in Zimbabwe and the Supa Ngwao Museum in Botswana. The second phase of data collection entailed modelling workshops in which educators engaged in discussion around the status of heritage education in post apartheid South Africa. This highlighted, through modelled lessons, some of the tensions, challenges and implications for working with notions of social transformation and inclusivity in heritage education. The third phase of data collection involved in-depth interviews. Twelve purposively selected research participants were interviewed between 2010 and 2011. Data generated across the study was processed and subjected to different levels of critical discourse analysis. Besides noting how heritage education in post colonial southern Africa is poorly framed and under-researched, this study revealed that current forms of representing indigenous heritage constructs are influenced more by socio-political discourses than the need to protect and conserve local heritage resources. The study also noted that the observed heritage education practices are oriented more towards addressing issues related to marginalisation and alienation of indigenous cultures and practices, than enhancing learners’ agency to manage and utilise local heritage resources in a more sustainable ways. Based on these findings the study recommends re-positioning heritage education within the framework of Education for Sustainable Development (ESD). ESD acknowledges both issues of social justice and the dialectical interplay between nature and culture; as such, it may allow for representation and use of indigenous heritage constructs in ways that expand current political orientations to include sustainability as an additional objective of heritage education. Given that little research focusing on heritage education has been undertaken within southern Africa, the findings of this study provide a basis upon which future research may emerge.
- Full Text:
- Date Issued: 2013
- Authors: Zazu, Cryton
- Date: 2013
- Subjects: Albany Museum (Grahamstown, South Africa) Cultural property -- Conservation and restoration -- Research -- Africa, Southern Great Zimbabwe (Extinct city) Indigenous peoples -- Material culture -- Africa, Southern Anthropological museums and collections -- Management -- Research -- Africa, Southern Cultural property -- Management -- Research Ethnoscience -- Study and teaching -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1407 , http://hdl.handle.net/10962/d1002015
- Description: This study explores representation and use of indigenous heritage constructs with a view to identifying implications thereof for the quality and relevance of heritage education practices in post colonial southern Africa. Framed within a critical hermeneutic research paradigm under-laboured by critical realist ontology, the study was conducted using a multiple case study research design. The data collection protocol was three-phased, starting with a process of contextual profiling, within which insights were gained into discourses shaping the constitution and orientation of heritage education practices at the Albany Museum in South Africa, the Great Zimbabwe Monument in Zimbabwe and the Supa Ngwao Museum in Botswana. The second phase of data collection entailed modelling workshops in which educators engaged in discussion around the status of heritage education in post apartheid South Africa. This highlighted, through modelled lessons, some of the tensions, challenges and implications for working with notions of social transformation and inclusivity in heritage education. The third phase of data collection involved in-depth interviews. Twelve purposively selected research participants were interviewed between 2010 and 2011. Data generated across the study was processed and subjected to different levels of critical discourse analysis. Besides noting how heritage education in post colonial southern Africa is poorly framed and under-researched, this study revealed that current forms of representing indigenous heritage constructs are influenced more by socio-political discourses than the need to protect and conserve local heritage resources. The study also noted that the observed heritage education practices are oriented more towards addressing issues related to marginalisation and alienation of indigenous cultures and practices, than enhancing learners’ agency to manage and utilise local heritage resources in a more sustainable ways. Based on these findings the study recommends re-positioning heritage education within the framework of Education for Sustainable Development (ESD). ESD acknowledges both issues of social justice and the dialectical interplay between nature and culture; as such, it may allow for representation and use of indigenous heritage constructs in ways that expand current political orientations to include sustainability as an additional objective of heritage education. Given that little research focusing on heritage education has been undertaken within southern Africa, the findings of this study provide a basis upon which future research may emerge.
- Full Text:
- Date Issued: 2013
Rural livelihoods, forest products and poverty alleviation: the role of markets
- Authors: Mutamba, Manyewu
- Date: 2013
- Subjects: Rural development -- Zambia Rural poor -- Zambia Zambia -- Rural conditions Forest management -- Zambia Forest conservation -- Zambia Households -- Economic aspects -- Zambia Forest products -- Zambia Forests and forestry -- Zambia Non-timber forest products -- Zambia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4741 , http://hdl.handle.net/10962/d1006081
- Description: There is growing acknowledgement that forests and forest products are central to rural livelihoods, but their role in lifting households out of poverty remains contentious. This study tested the assertion by proponents of forest based poverty alleviation that changing conditions in the use and management of forests and forest products has created opportunities for poor rural households to lift themselves out of poverty. The study used detailed annual income data from various household sectors in two contrasting sites in Zambia, namely Mufulira and Kabompo districts, analyzing the relative contribution of forest income to household livelihood, the effect of household wealth status on forest use, factors driving household participation in forest product trade, and the influence of distance to urban markets on trends in the use of forest products. The study found that forest based activities play a central role in the livelihoods of households in the two study sites, contributing close to half of total household income, and dwarfing the contribution of agricultural sectors such as cropping and livestock rearing which are generally regarded as the main income sources for rural households. Forest based sectors were also found to be particularly valuable sources of household cash, often coming at critical times to meet basic needs. The findings also revealed that without the contribution of forest income, the proportion of households that would fall below the poverty line would increase sharply in both study sites. Wealthier households earned higher magnitudes of both subsistence and cash income from forest based activities than their poorer counterparts. Even the share of total household income coming from forest based activities was also higher among these better-off households, confirming that these activities are lucrative and they are improving the wealth status of households. Household participation in forest product trade was found to be influenced by demographic factors such as number of productive household members, age and the education level of the household head. Economic factors such as the level of income from wage labour, household poverty level, and ownership of key assets such as a bicycle were found to be important. Distance of homestead from the forest was also found to be an important contextual variable. The influence of urban demand on the use of forest products by rural households was significant in the study area. Although local sales played an important part as a source of cash for households, the most preferred channels for trade were linked to urban markets, either through roadside markets, middlemen or direct sales to urban buyers. The study concluded that with improved local organization and support for product development and marketing, some forest based activities provide a viable poverty alleviation option for poor rural households who otherwise have limited economic opportunities to escape poverty.
- Full Text:
- Date Issued: 2013
- Authors: Mutamba, Manyewu
- Date: 2013
- Subjects: Rural development -- Zambia Rural poor -- Zambia Zambia -- Rural conditions Forest management -- Zambia Forest conservation -- Zambia Households -- Economic aspects -- Zambia Forest products -- Zambia Forests and forestry -- Zambia Non-timber forest products -- Zambia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4741 , http://hdl.handle.net/10962/d1006081
- Description: There is growing acknowledgement that forests and forest products are central to rural livelihoods, but their role in lifting households out of poverty remains contentious. This study tested the assertion by proponents of forest based poverty alleviation that changing conditions in the use and management of forests and forest products has created opportunities for poor rural households to lift themselves out of poverty. The study used detailed annual income data from various household sectors in two contrasting sites in Zambia, namely Mufulira and Kabompo districts, analyzing the relative contribution of forest income to household livelihood, the effect of household wealth status on forest use, factors driving household participation in forest product trade, and the influence of distance to urban markets on trends in the use of forest products. The study found that forest based activities play a central role in the livelihoods of households in the two study sites, contributing close to half of total household income, and dwarfing the contribution of agricultural sectors such as cropping and livestock rearing which are generally regarded as the main income sources for rural households. Forest based sectors were also found to be particularly valuable sources of household cash, often coming at critical times to meet basic needs. The findings also revealed that without the contribution of forest income, the proportion of households that would fall below the poverty line would increase sharply in both study sites. Wealthier households earned higher magnitudes of both subsistence and cash income from forest based activities than their poorer counterparts. Even the share of total household income coming from forest based activities was also higher among these better-off households, confirming that these activities are lucrative and they are improving the wealth status of households. Household participation in forest product trade was found to be influenced by demographic factors such as number of productive household members, age and the education level of the household head. Economic factors such as the level of income from wage labour, household poverty level, and ownership of key assets such as a bicycle were found to be important. Distance of homestead from the forest was also found to be an important contextual variable. The influence of urban demand on the use of forest products by rural households was significant in the study area. Although local sales played an important part as a source of cash for households, the most preferred channels for trade were linked to urban markets, either through roadside markets, middlemen or direct sales to urban buyers. The study concluded that with improved local organization and support for product development and marketing, some forest based activities provide a viable poverty alleviation option for poor rural households who otherwise have limited economic opportunities to escape poverty.
- Full Text:
- Date Issued: 2013
Rural women's representation and participation in local governance in the Masvingo and Mashonaland central provinces of Zimbabwe
- Authors: Kurebwa, Jeffrey
- Date: 2013
- Subjects: Local government -- Women -- Zimbabwe , Public administration -- Citizen participation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8313 , http://hdl.handle.net/10948/d1020085
- Description: This study focused on the representation and participation of rural women in local governance in the Masvingo and Mashonaland Central provinces of Zimbabwe. It argued that increased representation and participation of women in local governance, particularly as ward councillors and senior administrative employees, is important and should be pursued. This has the potential to change the local governance system. The research further argued that change is more likely to occur when elected women are supported by the presence of more women at the most senior administrative levels in the local governance system. The presence of more women is required if the local governance system is to become inclusive of the diversity of the people it represents, especially women. This study rejected the assumption that rural women are passive recipients of local governance since they contribute significantly in fulfilling household and community needs and interests. Through their knowledge and understanding of the construction of power relations at the local level, rural women have creatively managed to produce, reproduce and use alternative strategies which are based on their sexuality and traditional gender roles in challenging and transforming gender inequality at the local level and in improving the quality of rural women. A National Gender Management System (NGMS) that can be used to effectively promote gender equity, equality and justice in local authorities has been developed. It is desirable that the NGMS be established within the existing organisational framework of central and local governments in Zimbabwe. This should be connected to the national structures to ensure that local level activities are systematically accounted for at the national level. The NGMS recognises the strategic importance of building partnerships with social actors at all levels. Qualitative research method was used in the study. The study used both primary and secondary data in analysing the representation and participation of rural women in local governance in the two selected provinces in Zimbabwe, namely Masvingo and Mashonaland Central. Primary data was collected through in-depth interviews and survey questionnaires, while secondary data was gathered through a literature survey of relevant textbooks, newspapers, and peer-reviewed journals, reports and legislation. The research findings indicated that rural women face a number of constraints in getting access to and participating in local governance. Some of the constraints include; cultural beliefs; violence against women; lack of resources; lack of mutual support among women; domestic responsibilities; and institutional factors. The contributions of the research to the study of women in local governance are discussed. Recommendations to increase the participation of women in local governance are made. These include creating an enabling environment for women’s political empowerment, gender-responsive budgets, capacity-building programmes, establishment of gender focal points, gender management committees and teams, increasing women’s self-worth and changing perceptions by men. The study also found that decentralisation in Zimbabwe has not brought local governance closer to rural women due to the interweaving cultural, structural, physical and financial barriers local government faces in ensuring gender equality.
- Full Text:
- Date Issued: 2013
- Authors: Kurebwa, Jeffrey
- Date: 2013
- Subjects: Local government -- Women -- Zimbabwe , Public administration -- Citizen participation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8313 , http://hdl.handle.net/10948/d1020085
- Description: This study focused on the representation and participation of rural women in local governance in the Masvingo and Mashonaland Central provinces of Zimbabwe. It argued that increased representation and participation of women in local governance, particularly as ward councillors and senior administrative employees, is important and should be pursued. This has the potential to change the local governance system. The research further argued that change is more likely to occur when elected women are supported by the presence of more women at the most senior administrative levels in the local governance system. The presence of more women is required if the local governance system is to become inclusive of the diversity of the people it represents, especially women. This study rejected the assumption that rural women are passive recipients of local governance since they contribute significantly in fulfilling household and community needs and interests. Through their knowledge and understanding of the construction of power relations at the local level, rural women have creatively managed to produce, reproduce and use alternative strategies which are based on their sexuality and traditional gender roles in challenging and transforming gender inequality at the local level and in improving the quality of rural women. A National Gender Management System (NGMS) that can be used to effectively promote gender equity, equality and justice in local authorities has been developed. It is desirable that the NGMS be established within the existing organisational framework of central and local governments in Zimbabwe. This should be connected to the national structures to ensure that local level activities are systematically accounted for at the national level. The NGMS recognises the strategic importance of building partnerships with social actors at all levels. Qualitative research method was used in the study. The study used both primary and secondary data in analysing the representation and participation of rural women in local governance in the two selected provinces in Zimbabwe, namely Masvingo and Mashonaland Central. Primary data was collected through in-depth interviews and survey questionnaires, while secondary data was gathered through a literature survey of relevant textbooks, newspapers, and peer-reviewed journals, reports and legislation. The research findings indicated that rural women face a number of constraints in getting access to and participating in local governance. Some of the constraints include; cultural beliefs; violence against women; lack of resources; lack of mutual support among women; domestic responsibilities; and institutional factors. The contributions of the research to the study of women in local governance are discussed. Recommendations to increase the participation of women in local governance are made. These include creating an enabling environment for women’s political empowerment, gender-responsive budgets, capacity-building programmes, establishment of gender focal points, gender management committees and teams, increasing women’s self-worth and changing perceptions by men. The study also found that decentralisation in Zimbabwe has not brought local governance closer to rural women due to the interweaving cultural, structural, physical and financial barriers local government faces in ensuring gender equality.
- Full Text:
- Date Issued: 2013
Sedimentology and sequence stratigraphy of the Congo and Kalahari basins of South Central Africa and their evolution during the formation and break-up of West Gondwana
- Authors: Linol, Bastien
- Date: 2013
- Subjects: Sedimentary basins -- Africa , Sedimentology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10655 , http://hdl.handle.net/10948/d1012148 , Sedimentary basins -- Africa , Sedimentology
- Description: The high elevated (ca. 1100 m) continental Kalahari Basin (KB) of southern Africa and the linked lower lying (ca. 400 m) Congo Basin (CB) of central Africa preserve in their interiors extensive sedimentary rock sequences and sediments that represent a unique record of the Phanerozoic geodynamic and climatic evolution of sub-Saharan Africa. In this thesis, field observations and new borehole data from the Democratic Republic of Congo (DRC) and Botswana are integrated with new paleontology and geochronology to present a substantially revised stratigraphy for the CB, and south-central Africa in general. This work also introduces a new multiphase model for the subsidence and uplift history of the CB, and improves correlations with the Cape-Karoo Basin (CKB) of South Africa and the Paraná Basin (PB) of south-east Brazil. Four deep boreholes, each between 2 and 4.5 km deep, drilled in the centre of the CB in the 1950’s and 1970’s are re-examined together with the colonial literature (in French) and available seismic data. This stratigraphic and basin analysis is complemented with new U-Pb dates of detrital zircons from core-samples of two of the boreholes (Samba and Dekese), as well as from samples collected during field work in the Kwango region of the south-west DRC. This work, for the first time, constrains the maximum ages and source provenances of the successions in the CB. Following the Pan African orogens (ca. 650-530 Ma), extensive sequences of red beds were deposited by regional paleocurrents to the south. These are now best preserved (1 km thick) along the West Congo, Oubanguides, and Lufilian Belts surrounding the CB. Overlying a hiatus that represents most of the early-Paleozoic, is a 1 to 3 km thick succession of easterly derived glacial, and then continental sequences of the Karoo Supergroup. This succession records the first main episode of subsidence [10-15 m/Ma], interrupted by a phase of uplift that is likely related to far-field intracontinental deformation within Gondwana supercontinent during the Variscan and Cape Fold orogenies (ca. 250-330 Ma) at its peripheries. Detrital zircons from the lower Karoo diamictites are dated at 1.85-2.05 Ga and 1.37- 1.42 Ga, and thus sourced from Paleoproterozoic (Eburnean) and mid-Mesoproterozoic (Kibaran type-I) basement rocks in Uganda and Tanzania. Zircons from all the other successions in the CB date predominantly at 950-1050 Ma and 500-800 Ma. These are derived from sediment recycling of late-Mesoproterozoic (Kibaran type-II) and late- Neoproterozoic (Pan African) sources in the Central African Republic (CAR) and Chad. A distinct unconformity across the Karoo Supergroup in the CB is overlain by 500- 1000 m Jurassic-Cretaceous sequences, here named the Congo Supergroup. During initial rapid subsidence [10-50 m/Ma], late-Jurassic (Kimmeridgian) shallow marine to continental sedimentation attests to a short transgression of proto-Indian Ocean waters into the northern CB (at 160 m above present day sea-level), succeeded by widespread deposition of aeolian dunes that extend from the southern CB to the PB in South America. The youngest zircons from these aeolian sediments in the CB date at 190 Ma and 240-290 Ma, and most likely indicate the influence of extensive silicic volcanic ash derived from the proto-Andes along the south-western margin of Gondwana. Two superimposed mid-Cretaceous (Albian-Cenomanian) lacustrine sequences in the central CB record a succeeding, slower [10-15 m/Ma], phase of basin subsidence during the opening of the South Atlantic (ca. 85-135 Ma). These Cretaceous sequences are in turn truncated by another regional peneplanation surface covered by Cenozoic (Eocene) silcretized sands and alluviums of the Kalahari Group, only 50-250 m thick in the centre of the CB. Southward, on top of the Kalahari Plateau in the central desert region of north-west Botswana, new boreholes intercepted laterally equivalent condensed lacustrine carbonates and calcretes (20-50 m thick) covered by sands. These terrestrial sequences are key archives of late-Mesozoic – Cenozoic paleo-climate changes, yet they remain stratigraphically unresolved. This new analysis of the Phanerozoic continental basins of south-central Africa and their equivalents in South America, opens a fresh continental-scale window into how West Gondwana break-up and concomitant epeirogenic uplifts of Kalahari (>2 km) and Congo (>200 m) are linked to interactions between the lithosphere and mantle geodynamics, and how these processes likely affected global climate changes.
- Full Text:
- Date Issued: 2013
- Authors: Linol, Bastien
- Date: 2013
- Subjects: Sedimentary basins -- Africa , Sedimentology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10655 , http://hdl.handle.net/10948/d1012148 , Sedimentary basins -- Africa , Sedimentology
- Description: The high elevated (ca. 1100 m) continental Kalahari Basin (KB) of southern Africa and the linked lower lying (ca. 400 m) Congo Basin (CB) of central Africa preserve in their interiors extensive sedimentary rock sequences and sediments that represent a unique record of the Phanerozoic geodynamic and climatic evolution of sub-Saharan Africa. In this thesis, field observations and new borehole data from the Democratic Republic of Congo (DRC) and Botswana are integrated with new paleontology and geochronology to present a substantially revised stratigraphy for the CB, and south-central Africa in general. This work also introduces a new multiphase model for the subsidence and uplift history of the CB, and improves correlations with the Cape-Karoo Basin (CKB) of South Africa and the Paraná Basin (PB) of south-east Brazil. Four deep boreholes, each between 2 and 4.5 km deep, drilled in the centre of the CB in the 1950’s and 1970’s are re-examined together with the colonial literature (in French) and available seismic data. This stratigraphic and basin analysis is complemented with new U-Pb dates of detrital zircons from core-samples of two of the boreholes (Samba and Dekese), as well as from samples collected during field work in the Kwango region of the south-west DRC. This work, for the first time, constrains the maximum ages and source provenances of the successions in the CB. Following the Pan African orogens (ca. 650-530 Ma), extensive sequences of red beds were deposited by regional paleocurrents to the south. These are now best preserved (1 km thick) along the West Congo, Oubanguides, and Lufilian Belts surrounding the CB. Overlying a hiatus that represents most of the early-Paleozoic, is a 1 to 3 km thick succession of easterly derived glacial, and then continental sequences of the Karoo Supergroup. This succession records the first main episode of subsidence [10-15 m/Ma], interrupted by a phase of uplift that is likely related to far-field intracontinental deformation within Gondwana supercontinent during the Variscan and Cape Fold orogenies (ca. 250-330 Ma) at its peripheries. Detrital zircons from the lower Karoo diamictites are dated at 1.85-2.05 Ga and 1.37- 1.42 Ga, and thus sourced from Paleoproterozoic (Eburnean) and mid-Mesoproterozoic (Kibaran type-I) basement rocks in Uganda and Tanzania. Zircons from all the other successions in the CB date predominantly at 950-1050 Ma and 500-800 Ma. These are derived from sediment recycling of late-Mesoproterozoic (Kibaran type-II) and late- Neoproterozoic (Pan African) sources in the Central African Republic (CAR) and Chad. A distinct unconformity across the Karoo Supergroup in the CB is overlain by 500- 1000 m Jurassic-Cretaceous sequences, here named the Congo Supergroup. During initial rapid subsidence [10-50 m/Ma], late-Jurassic (Kimmeridgian) shallow marine to continental sedimentation attests to a short transgression of proto-Indian Ocean waters into the northern CB (at 160 m above present day sea-level), succeeded by widespread deposition of aeolian dunes that extend from the southern CB to the PB in South America. The youngest zircons from these aeolian sediments in the CB date at 190 Ma and 240-290 Ma, and most likely indicate the influence of extensive silicic volcanic ash derived from the proto-Andes along the south-western margin of Gondwana. Two superimposed mid-Cretaceous (Albian-Cenomanian) lacustrine sequences in the central CB record a succeeding, slower [10-15 m/Ma], phase of basin subsidence during the opening of the South Atlantic (ca. 85-135 Ma). These Cretaceous sequences are in turn truncated by another regional peneplanation surface covered by Cenozoic (Eocene) silcretized sands and alluviums of the Kalahari Group, only 50-250 m thick in the centre of the CB. Southward, on top of the Kalahari Plateau in the central desert region of north-west Botswana, new boreholes intercepted laterally equivalent condensed lacustrine carbonates and calcretes (20-50 m thick) covered by sands. These terrestrial sequences are key archives of late-Mesozoic – Cenozoic paleo-climate changes, yet they remain stratigraphically unresolved. This new analysis of the Phanerozoic continental basins of south-central Africa and their equivalents in South America, opens a fresh continental-scale window into how West Gondwana break-up and concomitant epeirogenic uplifts of Kalahari (>2 km) and Congo (>200 m) are linked to interactions between the lithosphere and mantle geodynamics, and how these processes likely affected global climate changes.
- Full Text:
- Date Issued: 2013
Self-esteem, coping and the psychology of infertility
- Authors: Jordaan, Hendrina Jacoba
- Date: 2013
- Subjects: Infertility -- Psychological aspects , Self-esteem -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9959 , http://hdl.handle.net/10948/d1020055
- Description: This exploratory-descriptive study, using multiple case studies, investigated the self-esteem, coping and psychology of infertility of a sample of individuals who have received infertility treatment at a privately managed health care unit. Infertility is a complex condition associated with the inability to conceive a child, frequently manifesting itself as a result of various biological factors. A literature review indicated that being on Artificial Reproductive Technology (ART) treatment significantly increases the stress in an individual. In an attempt to gain insight into the way patients undergoing infertility treatment find the strength to complete their treatment cycles, and to endure and overcome the pressures associated therewith, in order to continue their lives – in spite of a negative treatment/pregnancy result, the researcher found it necessary to investigate the self-esteem, coping and the psychology of patients undergoing infertility treatment. An exploratory descriptive research design was used and the participants were chosen by means of a non-probability purposive sampling procedure. The participants were given a package of questionnaires to complete under the supervision of the group facilitator and researcher, prior to, as well as after the intervention. The assessment consisted of a biographical questionnaire and two standardised paper and pencil measures. The participants’ self-esteem was explored using James Battle’s (1981) Culture-Free Self-Esteem Inventory; while the coping resources were explored using Hammer and Marting’s (1988) Coping Resource Inventory (CRI). Although these data were not analysable, due to the small sample size, it was utilised in a qualitative manner to support the findings from the qualitative data. The data were also gathered from the participants via a psychological intervention programme in the format of three focus group sessions. All the qualitative results were analysed, according to Tesch’s model of content analysis. The general finding was that the period of infertility treatment is experienced as both difficult and challenging by individuals, and that there is immense healing in the sharing of one’s narrative with other infertility patients. It also surfaced that selfesteem, especially one’s feelings of worth, is most affected by a diagnosis of infertility, as well as by going through the roller coaster of the emotions associated with the treatment and monthly cycle of infertility. It was evident from the narratives told by the participants that every domain of one’s self-esteem is affected by a diagnosis of infertility, and that the biggest challenge in maintaining a positive selfesteem seemed to be in finding a balance between one’s real self and one’s ideal self. Furthermore, this study found that the challenge related to coping for the participants in this study was to present a coherent life narrative to the ‘world’, despite intense feelings of being misunderstood by others, and being faced with the discourse of infertility, as part of one’s life script. The main coping responses utilized by participants included the re-channelling of one’s focus, using denial, seeking out familial and social support, bargaining with God, and nurturing hope and faith that this journey of infertility is merely just a journey and not a destination, with the destination that of being blessed with a biological child of one’s own.
- Full Text:
- Date Issued: 2013
- Authors: Jordaan, Hendrina Jacoba
- Date: 2013
- Subjects: Infertility -- Psychological aspects , Self-esteem -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9959 , http://hdl.handle.net/10948/d1020055
- Description: This exploratory-descriptive study, using multiple case studies, investigated the self-esteem, coping and psychology of infertility of a sample of individuals who have received infertility treatment at a privately managed health care unit. Infertility is a complex condition associated with the inability to conceive a child, frequently manifesting itself as a result of various biological factors. A literature review indicated that being on Artificial Reproductive Technology (ART) treatment significantly increases the stress in an individual. In an attempt to gain insight into the way patients undergoing infertility treatment find the strength to complete their treatment cycles, and to endure and overcome the pressures associated therewith, in order to continue their lives – in spite of a negative treatment/pregnancy result, the researcher found it necessary to investigate the self-esteem, coping and the psychology of patients undergoing infertility treatment. An exploratory descriptive research design was used and the participants were chosen by means of a non-probability purposive sampling procedure. The participants were given a package of questionnaires to complete under the supervision of the group facilitator and researcher, prior to, as well as after the intervention. The assessment consisted of a biographical questionnaire and two standardised paper and pencil measures. The participants’ self-esteem was explored using James Battle’s (1981) Culture-Free Self-Esteem Inventory; while the coping resources were explored using Hammer and Marting’s (1988) Coping Resource Inventory (CRI). Although these data were not analysable, due to the small sample size, it was utilised in a qualitative manner to support the findings from the qualitative data. The data were also gathered from the participants via a psychological intervention programme in the format of three focus group sessions. All the qualitative results were analysed, according to Tesch’s model of content analysis. The general finding was that the period of infertility treatment is experienced as both difficult and challenging by individuals, and that there is immense healing in the sharing of one’s narrative with other infertility patients. It also surfaced that selfesteem, especially one’s feelings of worth, is most affected by a diagnosis of infertility, as well as by going through the roller coaster of the emotions associated with the treatment and monthly cycle of infertility. It was evident from the narratives told by the participants that every domain of one’s self-esteem is affected by a diagnosis of infertility, and that the biggest challenge in maintaining a positive selfesteem seemed to be in finding a balance between one’s real self and one’s ideal self. Furthermore, this study found that the challenge related to coping for the participants in this study was to present a coherent life narrative to the ‘world’, despite intense feelings of being misunderstood by others, and being faced with the discourse of infertility, as part of one’s life script. The main coping responses utilized by participants included the re-channelling of one’s focus, using denial, seeking out familial and social support, bargaining with God, and nurturing hope and faith that this journey of infertility is merely just a journey and not a destination, with the destination that of being blessed with a biological child of one’s own.
- Full Text:
- Date Issued: 2013