Fire regimes in eastern coastal fynbos: drivers, ecology and management
- Authors: Kraaij, Tineke
- Date: 2012
- Subjects: Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10607 , http://hdl.handle.net/10948/d1008047 , Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Description: Conventional knowledge of fynbos fire ecology is based on the summer-autumn fire regimes of the western Cape Floral Kingdom (CFK) where the climate is Mediterranean. However, the climate in the eastern coastal-CFK is milder and rainfall occurs year-round, with presumed effects on fire regimes. The Garden Route National Park (GRNP) has recently been established in the region, in a landscape where indigenous forests, fire-prone fynbos shrublands and fire-sensitive plantations of invasive alien trees are interspersed. The park faces considerable challenges related to the management of fire, including significant pressure from the adjacent plantation industry to reduce wildfire hazard by burning fynbos at short intervals, and high levels of invasion by alien trees (largely Pinus species originating from plantations). This study sought to improve understanding of fire regimes in eastern coastal fynbos shrublands, and to provide guidelines for ecologically sound management of fire in the area. My approach entailed (i) an assessment of the context within which fire management was practiced during the past century; (ii) characterisation of the recent fire history and fire regime (1900–2010); (iii) characterisation of the seasonality of fire weather and lightning; (iv) estimation of minimum fire return intervals (FRIs) from juvenile periods and post-fire recruitment success of overstorey proteoids (non-sprouting, slow-maturing, serotinous Proteaceae); and (v) determination of the ecologically appropriate fire season from post-fire recruitment seasonality of proteoids. I established that historically, plantation protection enjoyed priority over fynbos conservation in the area that is now the GRNP. Fynbos close to plantations has most likely been compromised by frequent and low-intensity burning in the past, as well as by invasion by alien trees. In terms of area burnt (1900–2010), natural (lightning-ignited) fires dominated the fire regime, particularly in the east, whereas prescribed burning was relatively unimportant. Typical fire return intervals (FRIs; 8–26 years; 1980–2010) were comparable to those in other fynbos protected areas and appeared to be shorter in the eastern Tsitsikamma than in the western Outeniqua halves of the study area. Proteaceae juvenile periods (4–9 years) and post-fire recruitment success (following fires in ≥7 year-old vegetation) suggested that for biodiversity conservation purposes, FRIs should be no less than nine years in moist, productive fynbos. Increases in the total area burnt annually (since 1980) were correlated with long-term increases in average fire danger weather, suggesting that fire regime changes may be related to global change. Collectively, findings on the seasonality of actual fires and the seasonality of fire danger weather, lightning, and post-fire proteoid recruitment suggested that fires in eastern coastal fynbos are not limited to any particular season, and for this reason managers do not need to be concerned if fires occur in any season. The ecological requirements for higher fire intensity may nonetheless be constrained by a need for safety. I articulated these findings into ecological thresholds pertaining to the different elements of the fire regime in eastern coastal fynbos, to guide adaptive management of fire in the Garden Route National Park. I also recommended a fire management strategy for the park to address the aforementioned operational considerations within the constraints posed by ecological thresholds. Finally, I highlighted further research and monitoring needs.
- Full Text:
- Date Issued: 2012
- Authors: Kraaij, Tineke
- Date: 2012
- Subjects: Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10607 , http://hdl.handle.net/10948/d1008047 , Forest fires -- South Africa , Climatic changes , Prescribed burning , Fire ecology -- South Africa
- Description: Conventional knowledge of fynbos fire ecology is based on the summer-autumn fire regimes of the western Cape Floral Kingdom (CFK) where the climate is Mediterranean. However, the climate in the eastern coastal-CFK is milder and rainfall occurs year-round, with presumed effects on fire regimes. The Garden Route National Park (GRNP) has recently been established in the region, in a landscape where indigenous forests, fire-prone fynbos shrublands and fire-sensitive plantations of invasive alien trees are interspersed. The park faces considerable challenges related to the management of fire, including significant pressure from the adjacent plantation industry to reduce wildfire hazard by burning fynbos at short intervals, and high levels of invasion by alien trees (largely Pinus species originating from plantations). This study sought to improve understanding of fire regimes in eastern coastal fynbos shrublands, and to provide guidelines for ecologically sound management of fire in the area. My approach entailed (i) an assessment of the context within which fire management was practiced during the past century; (ii) characterisation of the recent fire history and fire regime (1900–2010); (iii) characterisation of the seasonality of fire weather and lightning; (iv) estimation of minimum fire return intervals (FRIs) from juvenile periods and post-fire recruitment success of overstorey proteoids (non-sprouting, slow-maturing, serotinous Proteaceae); and (v) determination of the ecologically appropriate fire season from post-fire recruitment seasonality of proteoids. I established that historically, plantation protection enjoyed priority over fynbos conservation in the area that is now the GRNP. Fynbos close to plantations has most likely been compromised by frequent and low-intensity burning in the past, as well as by invasion by alien trees. In terms of area burnt (1900–2010), natural (lightning-ignited) fires dominated the fire regime, particularly in the east, whereas prescribed burning was relatively unimportant. Typical fire return intervals (FRIs; 8–26 years; 1980–2010) were comparable to those in other fynbos protected areas and appeared to be shorter in the eastern Tsitsikamma than in the western Outeniqua halves of the study area. Proteaceae juvenile periods (4–9 years) and post-fire recruitment success (following fires in ≥7 year-old vegetation) suggested that for biodiversity conservation purposes, FRIs should be no less than nine years in moist, productive fynbos. Increases in the total area burnt annually (since 1980) were correlated with long-term increases in average fire danger weather, suggesting that fire regime changes may be related to global change. Collectively, findings on the seasonality of actual fires and the seasonality of fire danger weather, lightning, and post-fire proteoid recruitment suggested that fires in eastern coastal fynbos are not limited to any particular season, and for this reason managers do not need to be concerned if fires occur in any season. The ecological requirements for higher fire intensity may nonetheless be constrained by a need for safety. I articulated these findings into ecological thresholds pertaining to the different elements of the fire regime in eastern coastal fynbos, to guide adaptive management of fire in the Garden Route National Park. I also recommended a fire management strategy for the park to address the aforementioned operational considerations within the constraints posed by ecological thresholds. Finally, I highlighted further research and monitoring needs.
- Full Text:
- Date Issued: 2012
Force of habit the mystical foundations of the narcotic
- Authors: Howell, Simon Peter
- Date: 2012
- Subjects: Drug addiction -- Philosophy -- Research Drug addiction -- Political aspects -- Research Cocaine abuse -- Legal status, laws, etc. -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2784 , http://hdl.handle.net/10962/d1002994
- Description: This thesis aims to investigate and deconstruct the relationship between the narcotic, its narrative, and western modernity. To reveal the relationship, this thesis argues that it is possible to understand the philosophical, political, cultural and ethical dimensions of western modernity through the ulterior lens of the narcotic. As such, this thesis investigates western modernity's relationship to (a) cocaine as a specific narcotic, and (b) the concept of the narcotic with all its attendant connotations of addictions, illegitimacy, transgression, illegality, and so on. Accordingly, the thesis is both interpretive of the historical narrative of the narcotic of cocaine, and generative in its deconstruction of the relationship between western modernity and the concept of the narcotic. The deconstruction of this relationship ultimately reveals both prior narratives not as oppositional, but as supplementary. This has radical consequences for the manner in which we engage with narcotic use and the user - if the narcotic is supplement to the logic of western modernity, at each attempt to expel the use and user of the narcotic, rather then create difference, we self implicate ourselves in that expulsion and distance. To seek a new and more just means of dealing with the concept of the narcotic, and its use, therefore requires a new epistemological framework which can at once contemplate both narratives at the same time. To this end, the thesis suggests the use of critical complexity theory as one such methodological tool, if supplemented by the thoughts and strategies of Derridian deconstruction and Foucauldian discourse analysis.
- Full Text:
- Date Issued: 2012
- Authors: Howell, Simon Peter
- Date: 2012
- Subjects: Drug addiction -- Philosophy -- Research Drug addiction -- Political aspects -- Research Cocaine abuse -- Legal status, laws, etc. -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2784 , http://hdl.handle.net/10962/d1002994
- Description: This thesis aims to investigate and deconstruct the relationship between the narcotic, its narrative, and western modernity. To reveal the relationship, this thesis argues that it is possible to understand the philosophical, political, cultural and ethical dimensions of western modernity through the ulterior lens of the narcotic. As such, this thesis investigates western modernity's relationship to (a) cocaine as a specific narcotic, and (b) the concept of the narcotic with all its attendant connotations of addictions, illegitimacy, transgression, illegality, and so on. Accordingly, the thesis is both interpretive of the historical narrative of the narcotic of cocaine, and generative in its deconstruction of the relationship between western modernity and the concept of the narcotic. The deconstruction of this relationship ultimately reveals both prior narratives not as oppositional, but as supplementary. This has radical consequences for the manner in which we engage with narcotic use and the user - if the narcotic is supplement to the logic of western modernity, at each attempt to expel the use and user of the narcotic, rather then create difference, we self implicate ourselves in that expulsion and distance. To seek a new and more just means of dealing with the concept of the narcotic, and its use, therefore requires a new epistemological framework which can at once contemplate both narratives at the same time. To this end, the thesis suggests the use of critical complexity theory as one such methodological tool, if supplemented by the thoughts and strategies of Derridian deconstruction and Foucauldian discourse analysis.
- Full Text:
- Date Issued: 2012
Games as communication: an analysis of advertising in South Africa
- Authors: Wright, Bianca Maria-Teresa
- Date: 2012
- Subjects: Internet advertising , Branding (Marketing)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8417 , http://hdl.handle.net/10948/d1012929
- Description: Games as a form of communication have been examined by academics in the fields of game studies, narratology and media studies, among others, but the use of games to communicate advertising messages has not been adequately explored within the South African context. The study sought to investigate the phenomenon of advergaming, purpose-built games designed to communicate an advertising message, in South Africa, and to develop a model for the use of advergaming as a viral marketing tool in this context. Using a hybrid approach, the study examined the way that advertising agencies currently use advergames as well as the effectiveness of advergaming as a means to communicate a message. The study presents the results of a national survey of advertising agencies in South Africa, a content analysis of existing advergames and an analysis of three semi-structured group interview experiments conducted using selected advergames. The findings point to the potential of advergaming as a message communication tool, but also highlight the challenges that may hamper the widespread use of advergaming in South Africa. It proposes the use of the mobile environment as a means to reach a wider South African audience and in that way, overcome some of the obstacles to advergaming adoption. In addition, the results identify aspects of advergames that seem to correlate with the effectiveness of message communication.
- Full Text:
- Date Issued: 2012
- Authors: Wright, Bianca Maria-Teresa
- Date: 2012
- Subjects: Internet advertising , Branding (Marketing)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8417 , http://hdl.handle.net/10948/d1012929
- Description: Games as a form of communication have been examined by academics in the fields of game studies, narratology and media studies, among others, but the use of games to communicate advertising messages has not been adequately explored within the South African context. The study sought to investigate the phenomenon of advergaming, purpose-built games designed to communicate an advertising message, in South Africa, and to develop a model for the use of advergaming as a viral marketing tool in this context. Using a hybrid approach, the study examined the way that advertising agencies currently use advergames as well as the effectiveness of advergaming as a means to communicate a message. The study presents the results of a national survey of advertising agencies in South Africa, a content analysis of existing advergames and an analysis of three semi-structured group interview experiments conducted using selected advergames. The findings point to the potential of advergaming as a message communication tool, but also highlight the challenges that may hamper the widespread use of advergaming in South Africa. It proposes the use of the mobile environment as a means to reach a wider South African audience and in that way, overcome some of the obstacles to advergaming adoption. In addition, the results identify aspects of advergames that seem to correlate with the effectiveness of message communication.
- Full Text:
- Date Issued: 2012
Growth and characterization of ZnO nanorods using chemical bath deposition
- Authors: Urgessa, Zelalem Nigussa
- Date: 2012
- Subjects: Zinc oxide , Photoluminescence , Semiconductor nanocrystals , Semiconductors -- Materials , Chemical reactions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10559 , http://hdl.handle.net/10948/d1021124 , http://hdl.handle.net/10948/d1021119
- Description: Semiconductor devices are commonplace in every household. One application of semiconductors in particular, namely solid state lighting technology, is destined for a bright future. To this end, ZnO nanostructures have gained substantial interest in the research community, in part because of its requisite large direct band gap. Furthermore, the stability of the exciton (binding energy 60 meV) in this material, can lead to lasing action based on exciton recombination and possibly exciton interaction, even above room temperature. Therefore, it is very important to realize controllable growth of ZnO nanostructures and investigate their properties. The main motivation for this thesis is not only to successfully realize the controllable growth of ZnO nanorods, but also to investigate the structure, optical and electrical properties in detail by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy (steady state and time resolved) and X-ray diffraction (XRD). Furthermore, strong rectification in the ZnO/p-Si heterojunction is demonstrated. Nanorods have been successfully synthesized on silicon by a two-step process, involving the pre-coating of the substrate by a seed layer, followed by the chemical bath deposition of the nanorods. ZnO seed layers with particle sizes of about 5 nm are achieved by the thermal decomposition of zinc acetate dihydrate dissolved in ethanol. The effects of the seed layer density on the distribution, alignment and uniformity of subsequently grown nanorods were studied. The aspect ratio, orientation and distribution of nanorods are shown to be well controlled through adjusting the density of the ZnO nanoparticles pre-coated onto the substrates. It is shown that the seed layer is a prerequisite for the growth of well aligned ZnO nanorods on lattice mismatched Si substrate. The influence of various nanorod growth parameters on the morphology, optical and electrical properties of the nanorods were also systematically studied. These include the oxygen to zinc molar ratio, the pH of the growth solution, the concentration of the reactants, the growth temperature and growth time, different hydroxide precursors and the addition of surface passivating agents to the growth solution. By controlling these xii parameters different architectures of nanostructures, like spherical particles, well aligned nanorods, nanoflowers and thin films of different thicknesses are demonstrated. A possible growth mechanism for ZnO nanostructures in solution is proposed. XRD indicated that all the as-grown nanostructures produced above 45 C crystallize in the wurtzite structure and post growth annealing does not significantly enhance the crystalline quality of the material. In material grown at lower temperature, traces of zinc hydroxide were observed. The optical quality of the nanostructures was investigated using both steady-state PL and time-resolved (TR) PL from 4 K to room temperature. In the case of as-grown samples, both UV and defect related emissions have been observed for all nanostructures. The effect of post-growth annealing on the optical quality of the nanostructures was carefully examined. The effect of annealing in different atmospheres was also investigated. Regardless of the annealing environment annealing at a temperature as low as 300 C enhances the UV emission and suppresses defect related deep level emission. However, annealing above 500 C is required to out-diffuse hydrogen, the presence of which is deduced from the I4 line in the low temperature PL spectra of ZnO. TRPL was utilized to investigate lifetime decay profiles of nanorods upon different post growth treatments. The bound exciton lifetime strongly depends on the post-growth annealing temperature: the PL decay time is much faster for as grown rods, confirming the domination of surface assisted recombination. In general, the PL analysis showed that the PL of nanorods have the same characteristics as that of bulk ZnO, except for the stronger contribution from surface related bound excitons in the former case. Surface adsorbed impurities causing depletion and band bending in the near surface region is implied from both time resolved and steady state PL. Finally, although strong rectification in the ZnO/p-Si heterojunction is illustrated, no electroluminescence has been achieved. This is explained in terms of the band offset between ZnO and Si and interfacial states. Different schemes are proposed to improve the performance of ZnO/Si heterojunction light emitting devices.
- Full Text:
- Date Issued: 2012
- Authors: Urgessa, Zelalem Nigussa
- Date: 2012
- Subjects: Zinc oxide , Photoluminescence , Semiconductor nanocrystals , Semiconductors -- Materials , Chemical reactions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10559 , http://hdl.handle.net/10948/d1021124 , http://hdl.handle.net/10948/d1021119
- Description: Semiconductor devices are commonplace in every household. One application of semiconductors in particular, namely solid state lighting technology, is destined for a bright future. To this end, ZnO nanostructures have gained substantial interest in the research community, in part because of its requisite large direct band gap. Furthermore, the stability of the exciton (binding energy 60 meV) in this material, can lead to lasing action based on exciton recombination and possibly exciton interaction, even above room temperature. Therefore, it is very important to realize controllable growth of ZnO nanostructures and investigate their properties. The main motivation for this thesis is not only to successfully realize the controllable growth of ZnO nanorods, but also to investigate the structure, optical and electrical properties in detail by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy (steady state and time resolved) and X-ray diffraction (XRD). Furthermore, strong rectification in the ZnO/p-Si heterojunction is demonstrated. Nanorods have been successfully synthesized on silicon by a two-step process, involving the pre-coating of the substrate by a seed layer, followed by the chemical bath deposition of the nanorods. ZnO seed layers with particle sizes of about 5 nm are achieved by the thermal decomposition of zinc acetate dihydrate dissolved in ethanol. The effects of the seed layer density on the distribution, alignment and uniformity of subsequently grown nanorods were studied. The aspect ratio, orientation and distribution of nanorods are shown to be well controlled through adjusting the density of the ZnO nanoparticles pre-coated onto the substrates. It is shown that the seed layer is a prerequisite for the growth of well aligned ZnO nanorods on lattice mismatched Si substrate. The influence of various nanorod growth parameters on the morphology, optical and electrical properties of the nanorods were also systematically studied. These include the oxygen to zinc molar ratio, the pH of the growth solution, the concentration of the reactants, the growth temperature and growth time, different hydroxide precursors and the addition of surface passivating agents to the growth solution. By controlling these xii parameters different architectures of nanostructures, like spherical particles, well aligned nanorods, nanoflowers and thin films of different thicknesses are demonstrated. A possible growth mechanism for ZnO nanostructures in solution is proposed. XRD indicated that all the as-grown nanostructures produced above 45 C crystallize in the wurtzite structure and post growth annealing does not significantly enhance the crystalline quality of the material. In material grown at lower temperature, traces of zinc hydroxide were observed. The optical quality of the nanostructures was investigated using both steady-state PL and time-resolved (TR) PL from 4 K to room temperature. In the case of as-grown samples, both UV and defect related emissions have been observed for all nanostructures. The effect of post-growth annealing on the optical quality of the nanostructures was carefully examined. The effect of annealing in different atmospheres was also investigated. Regardless of the annealing environment annealing at a temperature as low as 300 C enhances the UV emission and suppresses defect related deep level emission. However, annealing above 500 C is required to out-diffuse hydrogen, the presence of which is deduced from the I4 line in the low temperature PL spectra of ZnO. TRPL was utilized to investigate lifetime decay profiles of nanorods upon different post growth treatments. The bound exciton lifetime strongly depends on the post-growth annealing temperature: the PL decay time is much faster for as grown rods, confirming the domination of surface assisted recombination. In general, the PL analysis showed that the PL of nanorods have the same characteristics as that of bulk ZnO, except for the stronger contribution from surface related bound excitons in the former case. Surface adsorbed impurities causing depletion and band bending in the near surface region is implied from both time resolved and steady state PL. Finally, although strong rectification in the ZnO/p-Si heterojunction is illustrated, no electroluminescence has been achieved. This is explained in terms of the band offset between ZnO and Si and interfacial states. Different schemes are proposed to improve the performance of ZnO/Si heterojunction light emitting devices.
- Full Text:
- Date Issued: 2012
Histopathological changes in male wistar rats maintained on a water-based sutherlandia frutescens extract
- Authors: Wickens, Nicolas John
- Date: 2012
- Subjects: Rats -- Physiology , Rats as laboratory animals
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/4742 , vital:20670
- Description: In this study a standardized 46 week chronic drinking water toxicity protocol was used to elucidate the toxic potential of Sutherlandia frutescens (S. frutescens) using histopathologic, morphometric and transmission electron microscopic analysis. The histopathologic changes in the duodenum, heart, kidney, liver, lung, pancreas and spleen of male Wistar rats were evaluated. Fifty-four rats were randomly divided into four groups: Group 1 – Normal diet control (ND control), n=7, Group 2 – Normal diet + plant extract (ND + p), n=9, Group 3 – High fat diet control (HFD control), n=19Group 4 – High fat diet + p (HFD + p), n=19In the high fat group male Wistar rats were fed ±55 g/day of a specialised high fat diet over a 46 week period to induce obesity and an insulin resistant state. The treatment groups (groups 2 and 4) received a dose concentration of a tea extract of the S. frutescens plant in their drinking water daily. This study showed that the consumption of S. frutescens significantly reduces weight gain in male Wistar rats on a chronic high fat diet (p≤0.001 vs. HFD control group). S. frutescens appears to propagate periportal and centrilobular glycogen storage in rat hepatocytes in the experimental groups as exemplified by a significantly (p≤0.0001 vs. control groups) increased incidences of Periodic Acid Schiff (PAS) positive staining S. frutescens also reduced intracellular lipid accumulation as made evident by the significantly lower incidence of epicardial adipose tissue (EAT), hepatic steatosis and pancreatic interstitial fat. Obesity was associated with increased fibrotic lesions such as myocardial perivascular fibrosis, centrilobular hepatic fibrosis and pancreatic periductal fibrosis. Obesity associated hypertension contributed to the widespread and significant increase in the average lesion severity of arterial congestion in all organs in the HFD control group. Pulmonary infection was equally prevalent in all rats. Despite the complex histopathology in all groups, differences in the control groups, such as, the presence of a conservative polymorphonuclear leukocyte (PMNL) infiltration, substantial intra-alveolar oedema and focal arterial wall hypertrophy in the control groups was highly suggestive of Sendai viral infection. However histopathologic evidence, in the treatment groups, suggested chronic recurrent viral infection with superimposed Mycoplasma pulmonis (M. pulmonis) bacterial infection. The impact of advanced suppurative pulmonary infection was widespread and exemplified by increased lesion incidences of spontaneous murine progressive cardiomyopathy (MCP) and spontaneous chronic progressive nephropathy (CPN) among others. In conclusion S. frutescens administered for 46 weeks to male Wistar rats significantly lowered intracellular lipid accumulation and obesity associated myocardial, renal, hepatobiliary, pulmonary and pancreatic histopathology. Moreover, duodenal, cardiovascular, hepatobiliary, pulmonary, renal, pancreatic and splenic tissue did not show histopathologic evidence of direct plant extract associated toxicity or carcinogenicity.
- Full Text:
- Date Issued: 2012
- Authors: Wickens, Nicolas John
- Date: 2012
- Subjects: Rats -- Physiology , Rats as laboratory animals
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: http://hdl.handle.net/10948/4742 , vital:20670
- Description: In this study a standardized 46 week chronic drinking water toxicity protocol was used to elucidate the toxic potential of Sutherlandia frutescens (S. frutescens) using histopathologic, morphometric and transmission electron microscopic analysis. The histopathologic changes in the duodenum, heart, kidney, liver, lung, pancreas and spleen of male Wistar rats were evaluated. Fifty-four rats were randomly divided into four groups: Group 1 – Normal diet control (ND control), n=7, Group 2 – Normal diet + plant extract (ND + p), n=9, Group 3 – High fat diet control (HFD control), n=19Group 4 – High fat diet + p (HFD + p), n=19In the high fat group male Wistar rats were fed ±55 g/day of a specialised high fat diet over a 46 week period to induce obesity and an insulin resistant state. The treatment groups (groups 2 and 4) received a dose concentration of a tea extract of the S. frutescens plant in their drinking water daily. This study showed that the consumption of S. frutescens significantly reduces weight gain in male Wistar rats on a chronic high fat diet (p≤0.001 vs. HFD control group). S. frutescens appears to propagate periportal and centrilobular glycogen storage in rat hepatocytes in the experimental groups as exemplified by a significantly (p≤0.0001 vs. control groups) increased incidences of Periodic Acid Schiff (PAS) positive staining S. frutescens also reduced intracellular lipid accumulation as made evident by the significantly lower incidence of epicardial adipose tissue (EAT), hepatic steatosis and pancreatic interstitial fat. Obesity was associated with increased fibrotic lesions such as myocardial perivascular fibrosis, centrilobular hepatic fibrosis and pancreatic periductal fibrosis. Obesity associated hypertension contributed to the widespread and significant increase in the average lesion severity of arterial congestion in all organs in the HFD control group. Pulmonary infection was equally prevalent in all rats. Despite the complex histopathology in all groups, differences in the control groups, such as, the presence of a conservative polymorphonuclear leukocyte (PMNL) infiltration, substantial intra-alveolar oedema and focal arterial wall hypertrophy in the control groups was highly suggestive of Sendai viral infection. However histopathologic evidence, in the treatment groups, suggested chronic recurrent viral infection with superimposed Mycoplasma pulmonis (M. pulmonis) bacterial infection. The impact of advanced suppurative pulmonary infection was widespread and exemplified by increased lesion incidences of spontaneous murine progressive cardiomyopathy (MCP) and spontaneous chronic progressive nephropathy (CPN) among others. In conclusion S. frutescens administered for 46 weeks to male Wistar rats significantly lowered intracellular lipid accumulation and obesity associated myocardial, renal, hepatobiliary, pulmonary and pancreatic histopathology. Moreover, duodenal, cardiovascular, hepatobiliary, pulmonary, renal, pancreatic and splenic tissue did not show histopathologic evidence of direct plant extract associated toxicity or carcinogenicity.
- Full Text:
- Date Issued: 2012
Hiv/Aids communication and youth behaviour in South Africa: a study of female high school students in the Eastern Cape Province
- Authors: Mpofu, Nkosinothando
- Date: 2012
- Subjects: HIV infections -- Social aspects -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , Communication in public health -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Com)
- Identifier: vital:11368 , http://hdl.handle.net/10353/d1015374 , HIV infections -- Social aspects -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , Communication in public health -- South Africa
- Description: Human Immuno-Deficiency Virus and Acquired Immune-Deficiency Syndrome communication remains one of the most significant tools in the fight against HIV/AIDS given the absence of the cure to fight the growth and spread of the global pandemic. Through the use of information, HIV/AIDS communication seeks to empower recipients or societies with skills that will help reduce their risk of infection. South Africa has seen a high visibility of HIV/AIDS communication programmes or campaigns aimed at empowering different audiences, whilst paying particular emphasis on the most vulnerable. Young people, in particular young women, have a higher prevalence of HIV/AIDS in South Africa. This has prompted the development of many youth focused communication campaigns which have sought to address factors that increase young people`s vulnerability to HIV infection. However, despite the high visibility of HIV/AIDS communication campaigns targeting young people, high risk behaviours are still being seen among young women. Important to note are the high teenage pregnancy rates, growing abuse of substances and even the premature engagement of sexual activities among female youths. This, therefore, raises questions on the effect of HIV/AIDS communication programmes in encouraging protective behaviour against risky behavioural practices amongst young women. Using both quantitative and qualitative research approaches to this study, an investigation was conducted into whether current HIV/AIDS communication campaigns have been limited (in terms of effectiveness) when it comes to communicating with young women on issues relating to HIV/AIDS. Awareness of HIV/AIDS and HIV/AIDS communication programmes, relevance of HIV/AIDS communication programmes, the factors that influence the use and understanding of HIV/AIDS messages and the impact of HIV/AIDS communication on attitude and behaviour change amongst female youths is measured. A total of 350 questionnaire copies were self-administered to 350 participants, with a 100 percent response rate. From the 350 participants, seventy five took part in focus group discussions. Data obtained was analysed using SPSS (for descriptive statistics), and the grounded theory. The results of the study indicate that all participants were aware of HIV/AIDS with at least 60% of the participants aware of at least three HIV/AIDS communication campaigns. When measuring the relevance of HIV/AIDS communication campaigns, participants (58%) indicate that issues discussed in most HIV/AIDS communication campaigns increased the relevance of HIV/AIDS messages to young women although such relevance was, for some respondents, affected by limited access to communication campaigns. Results also show that levels of knowledge and understanding of factors that expose young women to HIV infections differed amongst participants in as much as the factors that hinder the use of advice contained in HIV/AIDS messages also differed. Sixty-nine percent of the participants have knowledge and a better understanding of factors that expose young females to HIV infections. Twenty-five percent of the participants identified peer pressure, whilst 23% identified limited access to HIV/AIDS communication campaigns and another 18% identified a disregard of HIV/AIDS messages as significant factors that limit the ability of individuals to implement advice contained in HIV/AIDS messages. The results also indicate that although HIV/AIDS communication campaigns seem to have played a role in empowering some participants, there is still a significant minority whom communication has not effectively communicated with. Based on these findings, the study suggests, amongst other things, the need to intensify current HIV/AIDS communication campaigns through the provision of consistent messages on appropriate condom use, the identification of easily accessible communication channels and the development of thought provoking and attention grabbing campaigns as well as the need to continue to directly involve young women in the processes of their own development.
- Full Text:
- Date Issued: 2012
- Authors: Mpofu, Nkosinothando
- Date: 2012
- Subjects: HIV infections -- Social aspects -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , Communication in public health -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Com)
- Identifier: vital:11368 , http://hdl.handle.net/10353/d1015374 , HIV infections -- Social aspects -- South Africa , AIDS (Disease) -- Social aspects -- South Africa , Communication in public health -- South Africa
- Description: Human Immuno-Deficiency Virus and Acquired Immune-Deficiency Syndrome communication remains one of the most significant tools in the fight against HIV/AIDS given the absence of the cure to fight the growth and spread of the global pandemic. Through the use of information, HIV/AIDS communication seeks to empower recipients or societies with skills that will help reduce their risk of infection. South Africa has seen a high visibility of HIV/AIDS communication programmes or campaigns aimed at empowering different audiences, whilst paying particular emphasis on the most vulnerable. Young people, in particular young women, have a higher prevalence of HIV/AIDS in South Africa. This has prompted the development of many youth focused communication campaigns which have sought to address factors that increase young people`s vulnerability to HIV infection. However, despite the high visibility of HIV/AIDS communication campaigns targeting young people, high risk behaviours are still being seen among young women. Important to note are the high teenage pregnancy rates, growing abuse of substances and even the premature engagement of sexual activities among female youths. This, therefore, raises questions on the effect of HIV/AIDS communication programmes in encouraging protective behaviour against risky behavioural practices amongst young women. Using both quantitative and qualitative research approaches to this study, an investigation was conducted into whether current HIV/AIDS communication campaigns have been limited (in terms of effectiveness) when it comes to communicating with young women on issues relating to HIV/AIDS. Awareness of HIV/AIDS and HIV/AIDS communication programmes, relevance of HIV/AIDS communication programmes, the factors that influence the use and understanding of HIV/AIDS messages and the impact of HIV/AIDS communication on attitude and behaviour change amongst female youths is measured. A total of 350 questionnaire copies were self-administered to 350 participants, with a 100 percent response rate. From the 350 participants, seventy five took part in focus group discussions. Data obtained was analysed using SPSS (for descriptive statistics), and the grounded theory. The results of the study indicate that all participants were aware of HIV/AIDS with at least 60% of the participants aware of at least three HIV/AIDS communication campaigns. When measuring the relevance of HIV/AIDS communication campaigns, participants (58%) indicate that issues discussed in most HIV/AIDS communication campaigns increased the relevance of HIV/AIDS messages to young women although such relevance was, for some respondents, affected by limited access to communication campaigns. Results also show that levels of knowledge and understanding of factors that expose young women to HIV infections differed amongst participants in as much as the factors that hinder the use of advice contained in HIV/AIDS messages also differed. Sixty-nine percent of the participants have knowledge and a better understanding of factors that expose young females to HIV infections. Twenty-five percent of the participants identified peer pressure, whilst 23% identified limited access to HIV/AIDS communication campaigns and another 18% identified a disregard of HIV/AIDS messages as significant factors that limit the ability of individuals to implement advice contained in HIV/AIDS messages. The results also indicate that although HIV/AIDS communication campaigns seem to have played a role in empowering some participants, there is still a significant minority whom communication has not effectively communicated with. Based on these findings, the study suggests, amongst other things, the need to intensify current HIV/AIDS communication campaigns through the provision of consistent messages on appropriate condom use, the identification of easily accessible communication channels and the development of thought provoking and attention grabbing campaigns as well as the need to continue to directly involve young women in the processes of their own development.
- Full Text:
- Date Issued: 2012
Hydrological uncertainty analysis and scenario-based streamflow modelling for the Congo River Basin
- Authors: Tshimanga, Raphael Muamba
- Date: 2012
- Subjects: Congo River -- Regulation Hydrological surveys -- Congo River Watershed Water resources development -- Congo River Watershed Water resources development -- Environmental aspects -- Congo River Watershed Water supply -- Congo River Watershed River engineering -- Congo River Watershed
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6029 , http://hdl.handle.net/10962/d1006158
- Description: The effects of climate and environmental change are likely to exacerbate water stress in Africa over the next five decades. It appears obvious, therefore, that large river basins with considerable total renewable water resources will play a prominent role in regional cooperation to alleviate the pressure of water scarcity within Africa. However, managing water resources in the large river basins of Africa involves problems of data paucity, lack of technical resources and the sheer scale of the problem. These river basins are located in regions that are characterized by poverty, low levels of economic development and little food security. The rivers provide multiple goods and services that include hydro-power, water supply, fisheries, agriculture, transportation, and maintenance of aquatic ecosystems. Sustainable water resources management is a critical issue, but there is almost always insufficient data available to formulate adequate management strategies. These basins therefore represent some of the best test cases for the practical application of the science associated with the Predictions in Ungauged Basins (PUB). The thesis presents the results of a process-based hydrological modelling study in the Congo Basin. One of the primary objectives of this study was to establish a hydrological model for the whole Congo Basin, using available historical data. The secondary objective of the study was to use the model and assess the impacts of future environmental change on water resources of the Congo Basin. Given the lack of adequate data on the basin physical characteristics, the preliminary work consisted of assessing available global datasets and building a database of the basin physical characteristics. The database was used for both assessing relationships of similarities between features of physiographic settings in the basin (Chapters 3 and 4), and establishing models that adequately represent the basin hydrology (Chapters 5, 6, and 7). The representative model of the Congo Basin hydrology was then used to assess the impacts of future environmental changes on water resources availability of the Congo Basin (Chapter 8). Through assessment of the physical characteristics of the basin, relationships of similarities were used to determine homogenous regions with regard to rainfall variability, physiographic settings, and hydrological responses. The first observation that comes from this study is that these three categories of regional groups of homogenous characteristics are sensible with regards to their geographical settings, but the overlap and apparent relationships between them are weak. An explanation of this observation is that there are insufficient data, particularly associated with defining sub-surface processes, and it is possible that additional data would have assisted in the discrimination of more homogenous groups and better links between the different datasets. The model application in this study consisted of two phases: model calibration, using a manual approach, and the application of a physically-based a priori parameter estimation approach. While the first approach was designed to assess the general applicability of the model and identify major errors with regard to input data and model structure, the second approach aimed to establish an understanding of the processes and identify useful relationships between the model parameters and the variations in real hydrological processes. The second approach was also designed to quantify the sensitivity of the model outputs to the parameters of the model and to encompass information sharing between the basin physical characteristics and quantifying the parameters of the model. Collectively, the study’s findings show that these two approaches work well and are appropriate to represent the real hydrological processes of Congo Basin. The secondary objective of this study was achieved by forcing the hydrological model developed for the Congo Basin with downscaled Global Climate Model (GCMs) data in order to assess scenarios of change and future possible impacts on water resources availability within the basin. The results provide useful lessons in terms of basin-wide adaptation measures to future climates. The lessons suggest that there is a risk of developing inappropriate adaptation measures to future climate change based on large scale hydrological response, as the response at small scales shows a completely different picture from that which is based on large scale predictions. While the study has concluded that the application of the hydrological model has been successful and can be used with some degree of confidence for enhanced decision making, there remain a number of uncertainties and opportunities to improve the methods used for water resources assessment within the basin. The focus of future activities from the perspective of practical application should be on improved access to data collection to increase confidence in model predictions, on dissemination of the knowledge generated by this study, and on training in the use of the developed water resources assessment techniques.
- Full Text:
- Date Issued: 2012
- Authors: Tshimanga, Raphael Muamba
- Date: 2012
- Subjects: Congo River -- Regulation Hydrological surveys -- Congo River Watershed Water resources development -- Congo River Watershed Water resources development -- Environmental aspects -- Congo River Watershed Water supply -- Congo River Watershed River engineering -- Congo River Watershed
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6029 , http://hdl.handle.net/10962/d1006158
- Description: The effects of climate and environmental change are likely to exacerbate water stress in Africa over the next five decades. It appears obvious, therefore, that large river basins with considerable total renewable water resources will play a prominent role in regional cooperation to alleviate the pressure of water scarcity within Africa. However, managing water resources in the large river basins of Africa involves problems of data paucity, lack of technical resources and the sheer scale of the problem. These river basins are located in regions that are characterized by poverty, low levels of economic development and little food security. The rivers provide multiple goods and services that include hydro-power, water supply, fisheries, agriculture, transportation, and maintenance of aquatic ecosystems. Sustainable water resources management is a critical issue, but there is almost always insufficient data available to formulate adequate management strategies. These basins therefore represent some of the best test cases for the practical application of the science associated with the Predictions in Ungauged Basins (PUB). The thesis presents the results of a process-based hydrological modelling study in the Congo Basin. One of the primary objectives of this study was to establish a hydrological model for the whole Congo Basin, using available historical data. The secondary objective of the study was to use the model and assess the impacts of future environmental change on water resources of the Congo Basin. Given the lack of adequate data on the basin physical characteristics, the preliminary work consisted of assessing available global datasets and building a database of the basin physical characteristics. The database was used for both assessing relationships of similarities between features of physiographic settings in the basin (Chapters 3 and 4), and establishing models that adequately represent the basin hydrology (Chapters 5, 6, and 7). The representative model of the Congo Basin hydrology was then used to assess the impacts of future environmental changes on water resources availability of the Congo Basin (Chapter 8). Through assessment of the physical characteristics of the basin, relationships of similarities were used to determine homogenous regions with regard to rainfall variability, physiographic settings, and hydrological responses. The first observation that comes from this study is that these three categories of regional groups of homogenous characteristics are sensible with regards to their geographical settings, but the overlap and apparent relationships between them are weak. An explanation of this observation is that there are insufficient data, particularly associated with defining sub-surface processes, and it is possible that additional data would have assisted in the discrimination of more homogenous groups and better links between the different datasets. The model application in this study consisted of two phases: model calibration, using a manual approach, and the application of a physically-based a priori parameter estimation approach. While the first approach was designed to assess the general applicability of the model and identify major errors with regard to input data and model structure, the second approach aimed to establish an understanding of the processes and identify useful relationships between the model parameters and the variations in real hydrological processes. The second approach was also designed to quantify the sensitivity of the model outputs to the parameters of the model and to encompass information sharing between the basin physical characteristics and quantifying the parameters of the model. Collectively, the study’s findings show that these two approaches work well and are appropriate to represent the real hydrological processes of Congo Basin. The secondary objective of this study was achieved by forcing the hydrological model developed for the Congo Basin with downscaled Global Climate Model (GCMs) data in order to assess scenarios of change and future possible impacts on water resources availability within the basin. The results provide useful lessons in terms of basin-wide adaptation measures to future climates. The lessons suggest that there is a risk of developing inappropriate adaptation measures to future climate change based on large scale hydrological response, as the response at small scales shows a completely different picture from that which is based on large scale predictions. While the study has concluded that the application of the hydrological model has been successful and can be used with some degree of confidence for enhanced decision making, there remain a number of uncertainties and opportunities to improve the methods used for water resources assessment within the basin. The focus of future activities from the perspective of practical application should be on improved access to data collection to increase confidence in model predictions, on dissemination of the knowledge generated by this study, and on training in the use of the developed water resources assessment techniques.
- Full Text:
- Date Issued: 2012
Identification of novel marine algal compounds with differential anti-cancer activity: towards a cancer stem-cell specific chemotherapy
- Authors: De la Mare, Jo-Anne
- Date: 2012
- Subjects: Breast -- Cancer , Stem cells -- Research , Chemotherapy , Algae -- Biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4143 , http://hdl.handle.net/10962/d1016250
- Description: Breast cancer remains the leading cause of cancer-related death in women worldwide. Furthermore, it has been demonstrated that the treatment-resistant ER-PR-HER2/neu- sub-type is more common among women of African descent, necessitating the search for novel chemotherapies for this form of the disease. The secondary metabolites produced by marine algae represent a rich source of structurally unique compounds with chemotherapeutic potential, particularly in South Africa, whose oceans allegedly host 15 % of the total number of species in the world. Indeed, a recent study reported the isolation of a range of novel compounds from South African red and brown algae of the Plocamium, Portiera and Sargassum genera which displayed cytotoxicity against oesophageal cancer cells in vitro. The molecular mechanisms mediating this toxicity were unknown, as was the effect of these and similar compounds on metastatic ER-PR-HER2/neu- breast cancer cell lines or breast cancer stem cells. The current study aimed to address these questions by screening a library of twenty-two novel marine algal compounds for the ability to inhibit MDA-MB-231 and Hs578T breast cancer cells, while having no adverse effects on non-cancerous MCF12A breast epithelial cells. While twelve of these were toxic in the micromolar range against breast cancer cells, only the polyhalogenated monoterpenes RU004 and RU007, and the tetraprenylated quinone sargaquinoic acid (SQA) were identified as hit compounds based on the criteria that their cytotoxicity was specific to breast cancer and not healthy breast cells in vitro. On the other hand, the halogenated monoterpene RU015 was found to be highly toxic to both breast cancer and non-cancerous breast cell lines, while the halogenated monoterpene stereoisomers RU017 and RU018 were non-toxic to either of these cell lines. The mode of action of RU004, RU007, RU015 and SQA, together with the previously characterized carotenoid fucoxanthin (FXN), was assessed in terms of the type of cell death induced and the effect on cell cycle distribution of these compounds. Flow cytometric analysis of the extent of Hoescht 33342 and propidium iodide staining along with PARP cleavage studies suggested that SQA induced apoptosis in MDA-MB-231 cells. On the other hand, the highly toxic compound RU015 appeared to induce necrosis as evidenced by 50 kDa PARP cleavage product in MDA-MB-231 cells. The flow cytometry profiles of MDA-MB-231 and Hst578T cells treated with the hit compounds RU004 and RU007 were suggestive of the induction of apoptosis by these compounds. Cell cycle analysis by flow cytometry with propidium iodide staining revealed that both SQA and FXN induced G0-G1 arrest together with an increase in the apoptotic sub-G0 population, which agreed with previous reports in the literature. The molecular mechanism of action of SQA and FXN were further investigated by the identification of specific signal transducer molecules involved in mediating their anti-cancer activities. SQA was found to require the activity of numerous caspases, including caspase-3, -6, -8, -9, -10 and -13, for its cytotoxicity and was demonstrated to decrease the level of the antiapoptotic protein Bcl-2. On the other hand, FXN was shown to require caspase-1, -2, -3, -9 and - 10 for its toxicity. This, together with the ability to decrease the levels of Bcl-2, pointed to the involvement of the intrinsic pathway in particular in mediating the activity of FXN. The screening of algal compounds against non-cancerous breast epithelial cells carried out in this study, together with the investigation into their mechanisms of action, represent one of the few reports in which characterization of algal metabolites goes beyond the initial cytotoxicity assays. Finally, in order to assess the potential anti-cancer stem cell activity of the marine algal compounds, a subset of these was screened using a mammosphere assay technique developed in this study. The cancer stem cell (CSC) theory proposes that cancers arise from and are maintained by a specific subpopulation of cells able to undergo asymmetric cell division and termed CSCs. These CSCs are capable of anchorage-independent growth in serum-free culture conditions, such as those in the mammosphere assay. Using this assay, the novel halogenated monoterpene stereoisomers RU017 and RU018 were demonstrated to possess putative anti- CSC activity as evidenced by their ability to completely eliminate mammosphere formation in vitro. Furthermore, since RU017 and RU018 were non-toxic to both breast cancer and healthy breast cells, it appeared that the activity of the compounds was potentially specific to the CSCs. The results require further validation, but represent the first report of selective anti-CSC activity.
- Full Text:
- Date Issued: 2012
- Authors: De la Mare, Jo-Anne
- Date: 2012
- Subjects: Breast -- Cancer , Stem cells -- Research , Chemotherapy , Algae -- Biotechnology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4143 , http://hdl.handle.net/10962/d1016250
- Description: Breast cancer remains the leading cause of cancer-related death in women worldwide. Furthermore, it has been demonstrated that the treatment-resistant ER-PR-HER2/neu- sub-type is more common among women of African descent, necessitating the search for novel chemotherapies for this form of the disease. The secondary metabolites produced by marine algae represent a rich source of structurally unique compounds with chemotherapeutic potential, particularly in South Africa, whose oceans allegedly host 15 % of the total number of species in the world. Indeed, a recent study reported the isolation of a range of novel compounds from South African red and brown algae of the Plocamium, Portiera and Sargassum genera which displayed cytotoxicity against oesophageal cancer cells in vitro. The molecular mechanisms mediating this toxicity were unknown, as was the effect of these and similar compounds on metastatic ER-PR-HER2/neu- breast cancer cell lines or breast cancer stem cells. The current study aimed to address these questions by screening a library of twenty-two novel marine algal compounds for the ability to inhibit MDA-MB-231 and Hs578T breast cancer cells, while having no adverse effects on non-cancerous MCF12A breast epithelial cells. While twelve of these were toxic in the micromolar range against breast cancer cells, only the polyhalogenated monoterpenes RU004 and RU007, and the tetraprenylated quinone sargaquinoic acid (SQA) were identified as hit compounds based on the criteria that their cytotoxicity was specific to breast cancer and not healthy breast cells in vitro. On the other hand, the halogenated monoterpene RU015 was found to be highly toxic to both breast cancer and non-cancerous breast cell lines, while the halogenated monoterpene stereoisomers RU017 and RU018 were non-toxic to either of these cell lines. The mode of action of RU004, RU007, RU015 and SQA, together with the previously characterized carotenoid fucoxanthin (FXN), was assessed in terms of the type of cell death induced and the effect on cell cycle distribution of these compounds. Flow cytometric analysis of the extent of Hoescht 33342 and propidium iodide staining along with PARP cleavage studies suggested that SQA induced apoptosis in MDA-MB-231 cells. On the other hand, the highly toxic compound RU015 appeared to induce necrosis as evidenced by 50 kDa PARP cleavage product in MDA-MB-231 cells. The flow cytometry profiles of MDA-MB-231 and Hst578T cells treated with the hit compounds RU004 and RU007 were suggestive of the induction of apoptosis by these compounds. Cell cycle analysis by flow cytometry with propidium iodide staining revealed that both SQA and FXN induced G0-G1 arrest together with an increase in the apoptotic sub-G0 population, which agreed with previous reports in the literature. The molecular mechanism of action of SQA and FXN were further investigated by the identification of specific signal transducer molecules involved in mediating their anti-cancer activities. SQA was found to require the activity of numerous caspases, including caspase-3, -6, -8, -9, -10 and -13, for its cytotoxicity and was demonstrated to decrease the level of the antiapoptotic protein Bcl-2. On the other hand, FXN was shown to require caspase-1, -2, -3, -9 and - 10 for its toxicity. This, together with the ability to decrease the levels of Bcl-2, pointed to the involvement of the intrinsic pathway in particular in mediating the activity of FXN. The screening of algal compounds against non-cancerous breast epithelial cells carried out in this study, together with the investigation into their mechanisms of action, represent one of the few reports in which characterization of algal metabolites goes beyond the initial cytotoxicity assays. Finally, in order to assess the potential anti-cancer stem cell activity of the marine algal compounds, a subset of these was screened using a mammosphere assay technique developed in this study. The cancer stem cell (CSC) theory proposes that cancers arise from and are maintained by a specific subpopulation of cells able to undergo asymmetric cell division and termed CSCs. These CSCs are capable of anchorage-independent growth in serum-free culture conditions, such as those in the mammosphere assay. Using this assay, the novel halogenated monoterpene stereoisomers RU017 and RU018 were demonstrated to possess putative anti- CSC activity as evidenced by their ability to completely eliminate mammosphere formation in vitro. Furthermore, since RU017 and RU018 were non-toxic to both breast cancer and healthy breast cells, it appeared that the activity of the compounds was potentially specific to the CSCs. The results require further validation, but represent the first report of selective anti-CSC activity.
- Full Text:
- Date Issued: 2012
Integrated leadership : a leadership approach for school management teams
- Hendricks, Clarence Nowellin
- Authors: Hendricks, Clarence Nowellin
- Date: 2012
- Subjects: Educational leadership -- South Africa , School management and organization
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9575 , http://hdl.handle.net/10948/d1018610
- Description: School managers currently face major challenges of finding innovative ways to improve the quality of teaching and learning and ultimately student outcomes. This might be because contemporary leadership models promote either requisite curricular expertise or requisite leadership qualities or requisite norms and values which impact notably on teaching and learning. This study examined to which extent School Management Teams (SMT’s) contribute to the quality of teaching and learning when utilizing an integrated leadership approach in primary schools.The extent to which integrated leadership contributes to the quality of teaching and learning is investigated through an exploratory mixed method approach. Case studies in six different schools were conducted through both qualitative and quantitative research methods to obtain data regarding the thirty-six participants’ integrated leadership qualities. Data was gathered through focused group interviews, observations and a questionnaire. The Annual National Assessment results for two consecutive years (2010 and 2011) of grade three and six learners for literacy and numeracy were collected to determine the relationship between integrated leadership and quality teaching and learning and the extent to which integrated leadership impacted on student outcomes.The findings revealed that SMT’s confused integrated leadership with the utilization of qualities from a range of leadership styles each seeking to fit the purpose of an activity, and then claim they are employing an integrated leadership approach. Integrated leadership on the contrary is one leadership model with different qualities and when utilised as a complete package, in a unified manner, has the potential to have a significant impact on the quality of teaching and learning and ultimately student achievement. The findings also indicated that the majority of SMT members are either not utilising integrated leadership or occasionally utilise some of the integrated leadership qualities. This might be one of the main reasons for unsatisfactory academic performance in schools. Integrated leadership thus, when implemented in its totality at all times, possesses all the qualities to have a significant impact on the quality of teaching and learning nationally and internationally.
- Full Text:
- Date Issued: 2012
- Authors: Hendricks, Clarence Nowellin
- Date: 2012
- Subjects: Educational leadership -- South Africa , School management and organization
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9575 , http://hdl.handle.net/10948/d1018610
- Description: School managers currently face major challenges of finding innovative ways to improve the quality of teaching and learning and ultimately student outcomes. This might be because contemporary leadership models promote either requisite curricular expertise or requisite leadership qualities or requisite norms and values which impact notably on teaching and learning. This study examined to which extent School Management Teams (SMT’s) contribute to the quality of teaching and learning when utilizing an integrated leadership approach in primary schools.The extent to which integrated leadership contributes to the quality of teaching and learning is investigated through an exploratory mixed method approach. Case studies in six different schools were conducted through both qualitative and quantitative research methods to obtain data regarding the thirty-six participants’ integrated leadership qualities. Data was gathered through focused group interviews, observations and a questionnaire. The Annual National Assessment results for two consecutive years (2010 and 2011) of grade three and six learners for literacy and numeracy were collected to determine the relationship between integrated leadership and quality teaching and learning and the extent to which integrated leadership impacted on student outcomes.The findings revealed that SMT’s confused integrated leadership with the utilization of qualities from a range of leadership styles each seeking to fit the purpose of an activity, and then claim they are employing an integrated leadership approach. Integrated leadership on the contrary is one leadership model with different qualities and when utilised as a complete package, in a unified manner, has the potential to have a significant impact on the quality of teaching and learning and ultimately student achievement. The findings also indicated that the majority of SMT members are either not utilising integrated leadership or occasionally utilise some of the integrated leadership qualities. This might be one of the main reasons for unsatisfactory academic performance in schools. Integrated leadership thus, when implemented in its totality at all times, possesses all the qualities to have a significant impact on the quality of teaching and learning nationally and internationally.
- Full Text:
- Date Issued: 2012
Isolation, structural characterisation and evaluation of cytotoxic activity of natural products from selected South African marine red algae
- Authors: Knott, Michael George
- Date: 2012
- Subjects: Marine algae -- South Africa , Red algae -- South Africa , Pharmaceutical chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3862 , http://hdl.handle.net/10962/d1015460
- Description: The medicinal chemistry of selected marine algae indigenous to South Africa was investigated. Following the isolation and characterisation of a number of new and known compounds, the associated in vitro cytotoxic profiles of these new compounds was investigated. Plocamium maxillosum yielded two new cyclic polyhalogenated monoterpenes which were characterised as 2E-chloromethine-4E-chlorovinyl-4-methyl-5-cyclohexen-1-one (2.1) and 2Z-chloromethine-4E-chlorovinyl-4-methyl-5-cyclohexen-1-one (2.2) on the basis of one and two dimensional NMR spectroscopic data and MS analysis. These compounds were also found to have good cytotoxic activity against breast cancer cell lines. Although these compounds are based on a regular monoterpene skeleton, they represent an uncommon feature not often seen in cyclic halogenated monoterpenes from marine algae. Plocamium robertiae yielded one new cyclic polyhalogenated monoterpene identified as 4,5- dibromo-5-chloromethyl-1-chlorovinyl-2-chloro-methylcyclohexane (2.6) and one known compound called 2,4-dichloro-1-chlorovinyl-1-methylcyclohexane-5-ene or Plocamene D (2.9). Portieria hornemannii was collected from Port Edward in Natal and yielded three new compounds, namely; 3Z-1,6-dibromo-3-(bromomethylidene)-2,7-dichloro-7-methyloctane (3.1), 1E,3Z-1,6-dibromo-3-(bromomethylidene)-7-chloro-7-methyloct-1-ene (3.2), 1Z,3Z- 1,6-dibromo-3-(bromomethylidene)-7-chloro-7-methyloct-1-ene (3.3), and one known compound, namely; 3S,6R-6-bromo-3-(bromomethyl)-3,7-dichloro-7-methyloct-1-ene (3.4). Compounds 3.1 and 3.2 showed no cytotoxic activity against breast cancer cells. Another Portieria hornemannii sample was collected from Noordhoek in the Eastern Cape, it yielded one known compound referred to as 3Z-6-bromo-3-(bromomethylidene)-2,7- dichloro-7-methyloct-1-ene (3.5), as well as one new compound called portieric acid A (3.6) or 5-bromo-2-(bromomethylidene)-6-chloro-6-methylheptanoic acid. Portieric acid A showed slight cytotoxic activity and also represents a new class of compound within the genus Portieria. The isolation of secondary metabolites from the South African red alga, Laurencia glomerata, yielded two known compounds; 7-hydroxylaurene (4.9) and cis-neolaurencenyne (4.12), as well as one chamigrane related compound (4.11). Laurencia flexuosa yielded one known compound called 3Z-bromofucin (4.13). Using 1H NMR, GC and molecular systematics, a novel method for identifying different species of Laurencia was also investigated.
- Full Text:
- Date Issued: 2012
- Authors: Knott, Michael George
- Date: 2012
- Subjects: Marine algae -- South Africa , Red algae -- South Africa , Pharmaceutical chemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3862 , http://hdl.handle.net/10962/d1015460
- Description: The medicinal chemistry of selected marine algae indigenous to South Africa was investigated. Following the isolation and characterisation of a number of new and known compounds, the associated in vitro cytotoxic profiles of these new compounds was investigated. Plocamium maxillosum yielded two new cyclic polyhalogenated monoterpenes which were characterised as 2E-chloromethine-4E-chlorovinyl-4-methyl-5-cyclohexen-1-one (2.1) and 2Z-chloromethine-4E-chlorovinyl-4-methyl-5-cyclohexen-1-one (2.2) on the basis of one and two dimensional NMR spectroscopic data and MS analysis. These compounds were also found to have good cytotoxic activity against breast cancer cell lines. Although these compounds are based on a regular monoterpene skeleton, they represent an uncommon feature not often seen in cyclic halogenated monoterpenes from marine algae. Plocamium robertiae yielded one new cyclic polyhalogenated monoterpene identified as 4,5- dibromo-5-chloromethyl-1-chlorovinyl-2-chloro-methylcyclohexane (2.6) and one known compound called 2,4-dichloro-1-chlorovinyl-1-methylcyclohexane-5-ene or Plocamene D (2.9). Portieria hornemannii was collected from Port Edward in Natal and yielded three new compounds, namely; 3Z-1,6-dibromo-3-(bromomethylidene)-2,7-dichloro-7-methyloctane (3.1), 1E,3Z-1,6-dibromo-3-(bromomethylidene)-7-chloro-7-methyloct-1-ene (3.2), 1Z,3Z- 1,6-dibromo-3-(bromomethylidene)-7-chloro-7-methyloct-1-ene (3.3), and one known compound, namely; 3S,6R-6-bromo-3-(bromomethyl)-3,7-dichloro-7-methyloct-1-ene (3.4). Compounds 3.1 and 3.2 showed no cytotoxic activity against breast cancer cells. Another Portieria hornemannii sample was collected from Noordhoek in the Eastern Cape, it yielded one known compound referred to as 3Z-6-bromo-3-(bromomethylidene)-2,7- dichloro-7-methyloct-1-ene (3.5), as well as one new compound called portieric acid A (3.6) or 5-bromo-2-(bromomethylidene)-6-chloro-6-methylheptanoic acid. Portieric acid A showed slight cytotoxic activity and also represents a new class of compound within the genus Portieria. The isolation of secondary metabolites from the South African red alga, Laurencia glomerata, yielded two known compounds; 7-hydroxylaurene (4.9) and cis-neolaurencenyne (4.12), as well as one chamigrane related compound (4.11). Laurencia flexuosa yielded one known compound called 3Z-bromofucin (4.13). Using 1H NMR, GC and molecular systematics, a novel method for identifying different species of Laurencia was also investigated.
- Full Text:
- Date Issued: 2012
Knowledge retention strategies in selected Southern Africa public broadcasting corporations
- Authors: Dewah, Peterson
- Date: 2012
- Subjects: Knowledge management , Intellectual capital -- Management , Employee retention , Broadcasting -- South Africa , Broadcasting -- Zimbabwe , Broadcasting -- Botswana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11572 , http://hdl.handle.net/10353/438 , Knowledge management , Intellectual capital -- Management , Employee retention , Broadcasting -- South Africa , Broadcasting -- Zimbabwe , Broadcasting -- Botswana
- Description: Knowledge is now regarded as the most important resource surpassing other resources like land and capital. It is a foregone conclusion that knowledge flows out of organizations through various ways such as resignations, retirement and death yet, it does not seem as if organizations are employing strategies to retain such a vital component of production and service delivery. This study investigated the knowledge retention strategies in three Southern Africa Development Community (SADC) public broadcasting organizations of the South African Broadcasting Corporation in South African (SABC), the Department of Broadcasting Services (DBS) in Botswana and the Zimbabwe Broadcasting Corporation (ZBC) in Zimbabwe. The aim of this study was to establish how knowledge is captured and retained at such organizations. The objectives of the study were; to find out the types of strategies the three broadcasting organizations employ to capture and retain knowledge; establish how the three broadcasting organizational cultures enable knowledge acquisition, transfer, sharing and retention; establish the role of ICTs as tools and enablers of knowledge retention, creation, transfer and sharing in the three broadcasting organizations; and to propose recommendations on the best strategies for retention of knowledge in the three public broadcasting organizations as well as suggest areas for further and future research. v The study used the survey method and employed the triangulation design for data gathering. Data were collected from three SADC public broadcasting organizations. The population sample comprised 240 professional staff including 38 managers from different sections of the broadcasting organizations. The researcher collected data by administering a questionnaire to staff, interviews with managers and observations. Documentary analysis was also conducted in order to supplement data and fill in gaps. The researcher was mainly interested in gathering data that would give a comprehensive picture about knowledge retention methods in broadcasting organizations. There were four main findings. First, knowledge management as a relatively new concept and practice has not yet been properly embraced in the public broadcasting organization system in order to capture and retain knowledge that is acquired and generated in the organizations. There are no measures put in place in the organizations to retain the knowledge to ensure that once those who hold vital tacit knowledge are gone, the knowledge may still be available and accessible. Second, the study established that the respective organizational cultures impede on organizational knowledge retention. The study established that there was no culture of knowledge sharing. It also emerged that employees were not free to share their knowledge because of government regulations, prevailing political contexts, mistrust and general lack of incentive to share knowledge. Third, the study established that the organizations have no strategies or systems in place to capture the experts‟ knowledge or the knowledge of experienced staff and vi those approaching retiring age. The Human Resources Departments hold exit interviews that cover issues purely to do with why the person is leaving the organization instead of recording the work experiences and expertise of the departing employees. Fourth, the study revealed that the public broadcasting organizations still lag behind in collaborative and communicative technologies that facilitate knowledge transfer and sharing of tacit knowledge but retention of knowledge generally. The study also found that, some of the organizations studied did not have internet connectivity and websites were not yet functional, which hampered acquisition and sharing of knowledge for retention purposes. The importance of this study is that it has made a contribution and provided literature on knowledge retention strategies for public broadcasting corporations as part of knowledge management practice. On the basis of these findings the study recommended the following: appointment of knowledge management officers, establishment of Communities of Practice, encouraging knowledge sharing between employees, introduction of joint programmes with other broadcasting organizations by managers and their supervision of mentoring programmes; organizations to facilitate acquisition of information and communication technologies that enable knowledge management
- Full Text:
- Date Issued: 2012
- Authors: Dewah, Peterson
- Date: 2012
- Subjects: Knowledge management , Intellectual capital -- Management , Employee retention , Broadcasting -- South Africa , Broadcasting -- Zimbabwe , Broadcasting -- Botswana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11572 , http://hdl.handle.net/10353/438 , Knowledge management , Intellectual capital -- Management , Employee retention , Broadcasting -- South Africa , Broadcasting -- Zimbabwe , Broadcasting -- Botswana
- Description: Knowledge is now regarded as the most important resource surpassing other resources like land and capital. It is a foregone conclusion that knowledge flows out of organizations through various ways such as resignations, retirement and death yet, it does not seem as if organizations are employing strategies to retain such a vital component of production and service delivery. This study investigated the knowledge retention strategies in three Southern Africa Development Community (SADC) public broadcasting organizations of the South African Broadcasting Corporation in South African (SABC), the Department of Broadcasting Services (DBS) in Botswana and the Zimbabwe Broadcasting Corporation (ZBC) in Zimbabwe. The aim of this study was to establish how knowledge is captured and retained at such organizations. The objectives of the study were; to find out the types of strategies the three broadcasting organizations employ to capture and retain knowledge; establish how the three broadcasting organizational cultures enable knowledge acquisition, transfer, sharing and retention; establish the role of ICTs as tools and enablers of knowledge retention, creation, transfer and sharing in the three broadcasting organizations; and to propose recommendations on the best strategies for retention of knowledge in the three public broadcasting organizations as well as suggest areas for further and future research. v The study used the survey method and employed the triangulation design for data gathering. Data were collected from three SADC public broadcasting organizations. The population sample comprised 240 professional staff including 38 managers from different sections of the broadcasting organizations. The researcher collected data by administering a questionnaire to staff, interviews with managers and observations. Documentary analysis was also conducted in order to supplement data and fill in gaps. The researcher was mainly interested in gathering data that would give a comprehensive picture about knowledge retention methods in broadcasting organizations. There were four main findings. First, knowledge management as a relatively new concept and practice has not yet been properly embraced in the public broadcasting organization system in order to capture and retain knowledge that is acquired and generated in the organizations. There are no measures put in place in the organizations to retain the knowledge to ensure that once those who hold vital tacit knowledge are gone, the knowledge may still be available and accessible. Second, the study established that the respective organizational cultures impede on organizational knowledge retention. The study established that there was no culture of knowledge sharing. It also emerged that employees were not free to share their knowledge because of government regulations, prevailing political contexts, mistrust and general lack of incentive to share knowledge. Third, the study established that the organizations have no strategies or systems in place to capture the experts‟ knowledge or the knowledge of experienced staff and vi those approaching retiring age. The Human Resources Departments hold exit interviews that cover issues purely to do with why the person is leaving the organization instead of recording the work experiences and expertise of the departing employees. Fourth, the study revealed that the public broadcasting organizations still lag behind in collaborative and communicative technologies that facilitate knowledge transfer and sharing of tacit knowledge but retention of knowledge generally. The study also found that, some of the organizations studied did not have internet connectivity and websites were not yet functional, which hampered acquisition and sharing of knowledge for retention purposes. The importance of this study is that it has made a contribution and provided literature on knowledge retention strategies for public broadcasting corporations as part of knowledge management practice. On the basis of these findings the study recommended the following: appointment of knowledge management officers, establishment of Communities of Practice, encouraging knowledge sharing between employees, introduction of joint programmes with other broadcasting organizations by managers and their supervision of mentoring programmes; organizations to facilitate acquisition of information and communication technologies that enable knowledge management
- Full Text:
- Date Issued: 2012
Liquidity risk management by Zimbabwean commercial banks
- Authors: Chikoko, Laurine
- Date: 2012
- Subjects: Liquidity (Economics) , Banks and banking -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9027 , http://hdl.handle.net/10948/d1020344
- Description: Macroeconomic and financial market developments in Zimbabwe since 2000 have led to an increase in many banks‟ overall exposure to liquidity risk. The thesis highlights the importance of understanding and building comprehensive liquidity frameworks as defenses against liquidity stress. This study explores liquidity and liquidity risk management practices as well as the linkages and factors that affected different types of liquidity in the Zimbabwean banking sector during the Zimbabwean dollar and multiple currency eras. The research sought to present a comprehensive analysis of Zimbabwean commercial banks‟ liquidity risk management in challenging operating environments. Two periods were selected: January 2000 to December 2008 (the Zimbabwean dollar era) and March 2009 to June 2011 (the multiple currency era). Explanatory and survey research designs were used. The study applied econometric modeling using panel regression analysis to identify the major determinants of liquidity risk for 15 commercial banks in Zimbabwe. The financing gap ratio was used as the proxy for liquidity risk. The first investigation was on liquidity risk determinants in the Zimbabwean dollar era. The econometric investigations revealed that an increase in capital adequacy reduced liquidity risk and that there was a positive relationship between size and bank illiquidity. Liquidity risk was also explained by spreads. Inflation was positively related to liquidity risk and was a significant explanatory variable. Non-performing loans were not significant in explaining commercial banks‟ illiquidity, which is contrary to expectations. The second investigation was on commercial banks‟ liquidity risk determinants in the multiple currency era by using panel monthly data. The results showed that capital adequacy had a significant negative relationship with liquidity risk. The size of the bank was significant and positively related to bank illiquidity. Unlike in the Zimbabwean dollar era, spreads were negatively related to bank liquidity risk. Again, non-performing loans were a significant explanatory variable. The reserve requirements ratio and inflation also influenced bank illiquidity in the multiple currency regime. In both investigations, robustness tests for the main findings were done with an alternative dependent variable to the financing gap ratio. To complement the econometric analysis, a survey was conducted using questionnaires and interviews for the same 15 commercial banks. Empirical analysis in this research showed that during the 2000-2008 era; (i) no liquidity risk management guidelines were issued by the Reserve Bank of Zimbabwe until 2007. Banks relied on internal efforts in managing liquidity risk (ii) Liquidity was managed daily by treasury (iii) The operating environment was challenging with high inflation rates, which led to high demand for cash withdrawals by depositors (iv) Locally owned banks were more exposed to liquidity risk as compared to the foreign owned banks (v) Major sources of funds were new deposits, retention of maturities, shareholders, interbank borrowings, offshore lines of credit and also banks relied on the Reserve Bank of Zimbabwe as the lender of last resort (vi) Financial markets were active and banks offered a wide range of products (vii) To manage liquidity from depositors, banks relied on cash reserves, calculating and analysing the withdrawal patterns. When faced with cash shortages, banks relied on the daily limits set by the Reserve Bank of Zimbabwe (viii) Banks were lending but when the challenges deepened, they lent less in advances and increased investment in government securities. (ix) Inflation had major effects on liquidity risk management as it affected demand deposit tenors, fixed term products, corporate sector deposit mobilisation, cost of funds and investment portfolios (x) The regulatory environment was not favourable with RBZ policy measures designed to arrest inflation having negative repercussions on banks` liquidity management (xi) Banks had no liquidity crisis management frameworks. During the multiple currency exchange rate system (i) Commercial banks had problems in sourcing funds. They were mainly funded by transitory deposits with little coming in from treasury activities, interbank activities and offshore lines of credit. There was no lender of last resort function by the Reserve Bank of Zimbabwe. (ii) Some banks were still struggling to raise the minimum capital requirements (iii) Commercial banks offered narrow product ranges to clients (iv) To manage liquidity demand from clients, banks relied on the cash reserve ratio, and calculated the patterns of withdrawal, while some banks communicated with corporate clients on withdrawal schedules. (v) Zimbabwe commercial banks resumed the lending activity after dollarisation. Locally owned banks were aggressive, while foreign owned banks took a passive stance. There were problems with non-performing loans, especially from corporate clients, which exposed many banks to liquidity risk. (vi) Liquidity risk management in Zimbabwe was still guided by the Reserve Bank of Zimbabwe Risk Management Guideline BSD-04, 2007. All banks had liquidity risk management policies and procedure manuals but some banks were not adhering to them. Banks also had liquidity risk limits in place but some violated them. Furthermore, some banks were not conducting stress tests. Although all banks had contingency plans in place, none were testing them. Specifically, the research study highlighted the potential sources of liquidity risk in the Zimbabwean dollar and multiple currency periods. Based on the results, the study recommends survival strategies for banks in managing liquidity risk in such environments. It proposes a comprehensive liquidity management framework that clearly identifies, measures and control liquidity risk consistent with bank-specific and the country‟s macroeconomic developments. The envisaged framework would assist banks in dealing with illiquidity in a manner that would be less disruptive and that could render any future crisis less painful. Of importance is the recommendation that the central bank might not need to be too strict or too relaxed, but be moderate in ensuring an enabling regulatory environment. This would help banks to manage liquidity risk and at the same time protect depositors in any challenging operating environment. In both the studied time periods, there were transitory deposits. Generally there is need to inculcate a savings culture in Zimbabwe.
- Full Text:
- Date Issued: 2012
- Authors: Chikoko, Laurine
- Date: 2012
- Subjects: Liquidity (Economics) , Banks and banking -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9027 , http://hdl.handle.net/10948/d1020344
- Description: Macroeconomic and financial market developments in Zimbabwe since 2000 have led to an increase in many banks‟ overall exposure to liquidity risk. The thesis highlights the importance of understanding and building comprehensive liquidity frameworks as defenses against liquidity stress. This study explores liquidity and liquidity risk management practices as well as the linkages and factors that affected different types of liquidity in the Zimbabwean banking sector during the Zimbabwean dollar and multiple currency eras. The research sought to present a comprehensive analysis of Zimbabwean commercial banks‟ liquidity risk management in challenging operating environments. Two periods were selected: January 2000 to December 2008 (the Zimbabwean dollar era) and March 2009 to June 2011 (the multiple currency era). Explanatory and survey research designs were used. The study applied econometric modeling using panel regression analysis to identify the major determinants of liquidity risk for 15 commercial banks in Zimbabwe. The financing gap ratio was used as the proxy for liquidity risk. The first investigation was on liquidity risk determinants in the Zimbabwean dollar era. The econometric investigations revealed that an increase in capital adequacy reduced liquidity risk and that there was a positive relationship between size and bank illiquidity. Liquidity risk was also explained by spreads. Inflation was positively related to liquidity risk and was a significant explanatory variable. Non-performing loans were not significant in explaining commercial banks‟ illiquidity, which is contrary to expectations. The second investigation was on commercial banks‟ liquidity risk determinants in the multiple currency era by using panel monthly data. The results showed that capital adequacy had a significant negative relationship with liquidity risk. The size of the bank was significant and positively related to bank illiquidity. Unlike in the Zimbabwean dollar era, spreads were negatively related to bank liquidity risk. Again, non-performing loans were a significant explanatory variable. The reserve requirements ratio and inflation also influenced bank illiquidity in the multiple currency regime. In both investigations, robustness tests for the main findings were done with an alternative dependent variable to the financing gap ratio. To complement the econometric analysis, a survey was conducted using questionnaires and interviews for the same 15 commercial banks. Empirical analysis in this research showed that during the 2000-2008 era; (i) no liquidity risk management guidelines were issued by the Reserve Bank of Zimbabwe until 2007. Banks relied on internal efforts in managing liquidity risk (ii) Liquidity was managed daily by treasury (iii) The operating environment was challenging with high inflation rates, which led to high demand for cash withdrawals by depositors (iv) Locally owned banks were more exposed to liquidity risk as compared to the foreign owned banks (v) Major sources of funds were new deposits, retention of maturities, shareholders, interbank borrowings, offshore lines of credit and also banks relied on the Reserve Bank of Zimbabwe as the lender of last resort (vi) Financial markets were active and banks offered a wide range of products (vii) To manage liquidity from depositors, banks relied on cash reserves, calculating and analysing the withdrawal patterns. When faced with cash shortages, banks relied on the daily limits set by the Reserve Bank of Zimbabwe (viii) Banks were lending but when the challenges deepened, they lent less in advances and increased investment in government securities. (ix) Inflation had major effects on liquidity risk management as it affected demand deposit tenors, fixed term products, corporate sector deposit mobilisation, cost of funds and investment portfolios (x) The regulatory environment was not favourable with RBZ policy measures designed to arrest inflation having negative repercussions on banks` liquidity management (xi) Banks had no liquidity crisis management frameworks. During the multiple currency exchange rate system (i) Commercial banks had problems in sourcing funds. They were mainly funded by transitory deposits with little coming in from treasury activities, interbank activities and offshore lines of credit. There was no lender of last resort function by the Reserve Bank of Zimbabwe. (ii) Some banks were still struggling to raise the minimum capital requirements (iii) Commercial banks offered narrow product ranges to clients (iv) To manage liquidity demand from clients, banks relied on the cash reserve ratio, and calculated the patterns of withdrawal, while some banks communicated with corporate clients on withdrawal schedules. (v) Zimbabwe commercial banks resumed the lending activity after dollarisation. Locally owned banks were aggressive, while foreign owned banks took a passive stance. There were problems with non-performing loans, especially from corporate clients, which exposed many banks to liquidity risk. (vi) Liquidity risk management in Zimbabwe was still guided by the Reserve Bank of Zimbabwe Risk Management Guideline BSD-04, 2007. All banks had liquidity risk management policies and procedure manuals but some banks were not adhering to them. Banks also had liquidity risk limits in place but some violated them. Furthermore, some banks were not conducting stress tests. Although all banks had contingency plans in place, none were testing them. Specifically, the research study highlighted the potential sources of liquidity risk in the Zimbabwean dollar and multiple currency periods. Based on the results, the study recommends survival strategies for banks in managing liquidity risk in such environments. It proposes a comprehensive liquidity management framework that clearly identifies, measures and control liquidity risk consistent with bank-specific and the country‟s macroeconomic developments. The envisaged framework would assist banks in dealing with illiquidity in a manner that would be less disruptive and that could render any future crisis less painful. Of importance is the recommendation that the central bank might not need to be too strict or too relaxed, but be moderate in ensuring an enabling regulatory environment. This would help banks to manage liquidity risk and at the same time protect depositors in any challenging operating environment. In both the studied time periods, there were transitory deposits. Generally there is need to inculcate a savings culture in Zimbabwe.
- Full Text:
- Date Issued: 2012
Management perceptions regarding privatisation of parastatals in Zimbabwe
- Authors: Tshuma, Edward
- Date: 2012
- Subjects: Privatization -- Zimbabwe , Government business enterprises -- Zimbabwe , Zimbabwe -- Economic policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9324 , http://hdl.handle.net/10948/d1020923
- Description: In recent years the ownership of public organisations has been transferred from government to the private sector through privatisation owing to the poor performance of parastatals. In Zimbabwe, the privatisation of parastatals has been criticised as a result of the approach which has been adopted to privatise them, the transparency and the paceof the privatisation, the factors pushing for privatisation at the expense of local demand as well as the lack of an institutional framework for privatisation. The main objective of this study was to explore management perceptions regarding the privatisation of parastatals in Zimbabwe. This study is based on a combination of theories of privatisation and preceding results of studies looking at privatisation of parastatals in developing and developed countries. The secondary sources were the backbone in the formulation of a theoretical model on the management perceptions of privatisation which was used to guide this study. The extensive literature which was analysed revealed that independent factors such as stakeholder consultation, business conditions, government considerations, institutional framework and management of the privatisation process could influence management perceptions regarding privatisation. Perceptions of privatisation were identified as influencing two dependent variables, economic benefits and organisational performance. The variables of the study were operationalised and the hypotheses which identified relationships between the independent variables and perceptions of privatisation were formulated. Hypotheses in respect of perceptions of privatisation and the dependent variables were also formulated. In this study, a quantitative research approach was adopted as the study sought to investigate the relationships between variables. This study collected data through the use of a structured self-administered survey questionnaire which was distributed to 700 managers of parastatals in Zimbabwe. The parastatals which were used in this study were selected using the simple random sampling method whilst convenience sampling technique was used to select the managers. The survey yielded 301 usable questionnaires which were analysed using several statistical analysis techniques. The major findings of this study show that managers, employees and customers participate during privatisation and that privatisation in Zimbabwe is guided by a formal action plan. The study also showed that parastatals in Zimbabwe operate under stable macroeconomic conditions and that information regarding the bidding process is accessible to all parties. However, the results also showed that, in Zimbabwe privatisation is poorly implemented as a result of lack of structural capacity to enhance privatisation, lack of an autonomous institution to manage and lead the privatisation process. The results also show that privatisation in Zimbabwe lacks credibility as the valuation of organisations and assets is poorly done resulting in organisations being acquired at rates which are below market value. In addition, the results indicate that privatisation has failed to improve organisational performance and to change the management style from being reactive to being proactive. The study also found that privatisation brings about economic benefits such as effective governance and economic empowerment. The study recommends that government should ensure that managers, employees and customers participate in the privatisation process and that privatisation is implemented in a transparent manner so as to have a credible programme and achieve the intended objectives. The study also recommends that government should engage people and institutions which have the capacity to efficiently value the organisations and assets identified for privatisation. In addition, the study recommends that the government should appoint board members who possess the requisite skills and competencies, encourage partnerships between local and foreign investors so as to produce quality products and services as well as economic growth. This study has contributed to the existing body of knowledge by developing a theoretical model which can be utilised in other developing countries to test perceptions regarding the privatisation of parastatals. This study could assist the government, parastatals and other stakeholders by providing feedback regarding the privatisation of parastatals in Zimbabwe, so that remedial action can be implemented where deviations are recorded. The findings of this study could also assist the government of Zimbabwe and also other governments, by providing guidelines which can be adopted to implement a successful privatisation programme. This study provides useful and very practical guidelines to parastatals so as to ensure successful privatisation.
- Full Text:
- Date Issued: 2012
- Authors: Tshuma, Edward
- Date: 2012
- Subjects: Privatization -- Zimbabwe , Government business enterprises -- Zimbabwe , Zimbabwe -- Economic policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9324 , http://hdl.handle.net/10948/d1020923
- Description: In recent years the ownership of public organisations has been transferred from government to the private sector through privatisation owing to the poor performance of parastatals. In Zimbabwe, the privatisation of parastatals has been criticised as a result of the approach which has been adopted to privatise them, the transparency and the paceof the privatisation, the factors pushing for privatisation at the expense of local demand as well as the lack of an institutional framework for privatisation. The main objective of this study was to explore management perceptions regarding the privatisation of parastatals in Zimbabwe. This study is based on a combination of theories of privatisation and preceding results of studies looking at privatisation of parastatals in developing and developed countries. The secondary sources were the backbone in the formulation of a theoretical model on the management perceptions of privatisation which was used to guide this study. The extensive literature which was analysed revealed that independent factors such as stakeholder consultation, business conditions, government considerations, institutional framework and management of the privatisation process could influence management perceptions regarding privatisation. Perceptions of privatisation were identified as influencing two dependent variables, economic benefits and organisational performance. The variables of the study were operationalised and the hypotheses which identified relationships between the independent variables and perceptions of privatisation were formulated. Hypotheses in respect of perceptions of privatisation and the dependent variables were also formulated. In this study, a quantitative research approach was adopted as the study sought to investigate the relationships between variables. This study collected data through the use of a structured self-administered survey questionnaire which was distributed to 700 managers of parastatals in Zimbabwe. The parastatals which were used in this study were selected using the simple random sampling method whilst convenience sampling technique was used to select the managers. The survey yielded 301 usable questionnaires which were analysed using several statistical analysis techniques. The major findings of this study show that managers, employees and customers participate during privatisation and that privatisation in Zimbabwe is guided by a formal action plan. The study also showed that parastatals in Zimbabwe operate under stable macroeconomic conditions and that information regarding the bidding process is accessible to all parties. However, the results also showed that, in Zimbabwe privatisation is poorly implemented as a result of lack of structural capacity to enhance privatisation, lack of an autonomous institution to manage and lead the privatisation process. The results also show that privatisation in Zimbabwe lacks credibility as the valuation of organisations and assets is poorly done resulting in organisations being acquired at rates which are below market value. In addition, the results indicate that privatisation has failed to improve organisational performance and to change the management style from being reactive to being proactive. The study also found that privatisation brings about economic benefits such as effective governance and economic empowerment. The study recommends that government should ensure that managers, employees and customers participate in the privatisation process and that privatisation is implemented in a transparent manner so as to have a credible programme and achieve the intended objectives. The study also recommends that government should engage people and institutions which have the capacity to efficiently value the organisations and assets identified for privatisation. In addition, the study recommends that the government should appoint board members who possess the requisite skills and competencies, encourage partnerships between local and foreign investors so as to produce quality products and services as well as economic growth. This study has contributed to the existing body of knowledge by developing a theoretical model which can be utilised in other developing countries to test perceptions regarding the privatisation of parastatals. This study could assist the government, parastatals and other stakeholders by providing feedback regarding the privatisation of parastatals in Zimbabwe, so that remedial action can be implemented where deviations are recorded. The findings of this study could also assist the government of Zimbabwe and also other governments, by providing guidelines which can be adopted to implement a successful privatisation programme. This study provides useful and very practical guidelines to parastatals so as to ensure successful privatisation.
- Full Text:
- Date Issued: 2012
Management perceptions regarding skills shortages in gold mines
- Authors: Xingwana, Lumkwana
- Date: 2012
- Subjects: Labor supply--South Africa , Professional employees--South Africa , Occupational training--South Africa , Gold mines and mining--South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9279 , http://hdl.handle.net/10948/d1007959 , Labor supply--South Africa , Professional employees--South Africa , Occupational training--South Africa , Gold mines and mining--South Africa
- Description: The skills shortages in mining and mineral sector had existed for a decade and had a widespread effect on South Africa economy. It affects the level of economic productivity and reduces the country’s capacity to develop a knowledge society. This, in turn, affects the country’s functioning in the global economy. Despite the sector’s best efforts, the shortages continue to grow and threaten the delivery of projects and growth plans. Some researchers contend with the view that the persistence of skills shortages in mining and mineral sector is largely due to entrenched attitudes among both the industry and the community. They claim that employers have the means to change the educational profile of the subsectors by appointing recruits with higher levels of schooling. However, owing to the limited number of higher educated people living in the communities surrounding the mining operations and lack of interest in mining of people with higher levels of education, to name but few, employers are perceived to have a habit of employing people with little skills. The current study was aimed at investigating the impact of skills shortage on organisational performance, propensity to leave, competitive advantage and sustainability, from the management perceptive. The main objective of this study was to incorporate and embed previous research findings and theories into a comprehensive hypothetical model. A hypothetical model showed various factors that may influence skills shortage. Four independent variables (working environment, employment conditions, resources and education and training) were identified as variables that may influence skills shortage; and mediating variable (skills shortage) was also identified as a variable that have potential to affect dependent variables (organisational performance, propensity to leave, competitive advantage and sustainability) of gold mining sector. Furthermore, eight hypotheses were developed to test the relationship between independent, mediating and dependent variables. All these variables were clearly defined and operationalized with various items obtained from measuring instruments used in other similar studies. A purposive sample of 343 respondents was drawn from the population. A seven-point Likert scale and structured questionnaire were administered in person to the respondents and of which 300 were usable and subjected further to several statistical analyses. The validity and reliability of the measuring instrument was evaluated using significant effect p< = 0.001 and Pearson’s correlation test (α = 0.05). Data gathered were fed to and analysed by STATISTICA (version 10) and factor analysis and regression analyses were the statistical procedures used to test the significance of the relationships between the various independent and dependent variables. Consequently, working environment, resources and education and training were three independent variables that were identified as having ability to predict propensity to leave, competitive advantage and sustainability. An attempt was made to establish whether various demographic variables have an influence on mediating and dependent variables through the introduction of gender and position in the organisation while conducting an Analysis of Variance and Multiple linear regressions, but they obtained negative values. The conclusion is that demographic variables do not have over mediating and depended variables. The findings of this study states that with conducive working environment, availability of resources, the high levels of education and training, the country could produce skills that would reduce propensity to leave, drive competitive advantage and sustainability, innovation and entrepreneurship, create competitive advantages and boost employment sustainability.
- Full Text:
- Date Issued: 2012
- Authors: Xingwana, Lumkwana
- Date: 2012
- Subjects: Labor supply--South Africa , Professional employees--South Africa , Occupational training--South Africa , Gold mines and mining--South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9279 , http://hdl.handle.net/10948/d1007959 , Labor supply--South Africa , Professional employees--South Africa , Occupational training--South Africa , Gold mines and mining--South Africa
- Description: The skills shortages in mining and mineral sector had existed for a decade and had a widespread effect on South Africa economy. It affects the level of economic productivity and reduces the country’s capacity to develop a knowledge society. This, in turn, affects the country’s functioning in the global economy. Despite the sector’s best efforts, the shortages continue to grow and threaten the delivery of projects and growth plans. Some researchers contend with the view that the persistence of skills shortages in mining and mineral sector is largely due to entrenched attitudes among both the industry and the community. They claim that employers have the means to change the educational profile of the subsectors by appointing recruits with higher levels of schooling. However, owing to the limited number of higher educated people living in the communities surrounding the mining operations and lack of interest in mining of people with higher levels of education, to name but few, employers are perceived to have a habit of employing people with little skills. The current study was aimed at investigating the impact of skills shortage on organisational performance, propensity to leave, competitive advantage and sustainability, from the management perceptive. The main objective of this study was to incorporate and embed previous research findings and theories into a comprehensive hypothetical model. A hypothetical model showed various factors that may influence skills shortage. Four independent variables (working environment, employment conditions, resources and education and training) were identified as variables that may influence skills shortage; and mediating variable (skills shortage) was also identified as a variable that have potential to affect dependent variables (organisational performance, propensity to leave, competitive advantage and sustainability) of gold mining sector. Furthermore, eight hypotheses were developed to test the relationship between independent, mediating and dependent variables. All these variables were clearly defined and operationalized with various items obtained from measuring instruments used in other similar studies. A purposive sample of 343 respondents was drawn from the population. A seven-point Likert scale and structured questionnaire were administered in person to the respondents and of which 300 were usable and subjected further to several statistical analyses. The validity and reliability of the measuring instrument was evaluated using significant effect p< = 0.001 and Pearson’s correlation test (α = 0.05). Data gathered were fed to and analysed by STATISTICA (version 10) and factor analysis and regression analyses were the statistical procedures used to test the significance of the relationships between the various independent and dependent variables. Consequently, working environment, resources and education and training were three independent variables that were identified as having ability to predict propensity to leave, competitive advantage and sustainability. An attempt was made to establish whether various demographic variables have an influence on mediating and dependent variables through the introduction of gender and position in the organisation while conducting an Analysis of Variance and Multiple linear regressions, but they obtained negative values. The conclusion is that demographic variables do not have over mediating and depended variables. The findings of this study states that with conducive working environment, availability of resources, the high levels of education and training, the country could produce skills that would reduce propensity to leave, drive competitive advantage and sustainability, innovation and entrepreneurship, create competitive advantages and boost employment sustainability.
- Full Text:
- Date Issued: 2012
Marketers' perceptions of negotiation behaviour in a global scale
- Authors: Burhan, Ahmad Mtengwa
- Date: 2012
- Subjects: Negotiation in business -- Tanzania , Business enterprises -- Tanzania , Export marketing -- Tanzania
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: vital:9297 , http://hdl.handle.net/10948/d1013705
- Description: The success of international business depends on effective negotiations. Such negotiations do no happen in a vacuum, but usually in a specific environment that includes; time, surrounding, place, culture and people. The business environmental setting includes legal and political pluralism, currency fluctuations, foreign exchange, foreign government controls, bureaucracy, instability, change, ideological and cultural differences, as well as the influence of external stakeholders. These business negotiations environments can influence the behaviour of negotiation in global firms, impacting firms internationally. The reasons to negotiate on an international level may include considerations such as: choice of venue, culture to observe; and the outcome of the negotiation process. The aim of this study was to determine the influence of the international marketing environment, awareness of negotiation skill, interest groups and negotiation atmosphere on behaviour of marketers in a global firm. The study assessed the impact of negotiation behaviour on business agreements based on trust and certainty and level of commitment. The purpose of the study was to gauge the impact of negotiations behaviour pertaining to failure of business negotiations in Tanzania. In addition, the study endeavoured to determine the impact of environmental variables on the negotiation behaviour of marketers. The questionnaires used in the study comprised seven variables with statements linked to a five-point Likert-type interval scale varying from “strongly agree” to “strongly disagree. Self-administered questionnaires were used for data collection from global firms’ marketers and their management representatives; 323 questionnaires were collected from respondents. This study contributed to the literature on negotiation behaviour in a global firm and the perceptions of such global marketers in Tanzania. Many international companies in Tanzania find it difficult to formulate and implement a comprehensive business strategy; therefore, this study intends to equip international business managers with the leadership skills required. Based on the findings of this study, the negotiators and government are expected to play a major role in business negotiations to promote effective trade agreements despite limitations of political influence in the negotiation process. Political stability in a country enhances foreign business which in turn improves negotiation behaviour. A just legal system, with clear and unambiguous business guidelines and policies would benefit and promote local businesses and government representatives and negotiators in respect of international business negotiation behaviour. Reasonable tax and interest rates and fair business policies should improve international trade negotiations and business practices. In order to conduct successful international negotiations aspects such as culture, language differences, customs and traditions are important and should enjoy high priority. Aspects such as these mentioned influence the conducting and atmosphere and outcome of negotiations. The study reveals that the use of specialists and interpreters are imperative to guarantee understanding and successful outcomes. According to the findings negotiators should possess good negotiating skills to be able to steer the negotiation process through the different phases of negotiation that requires different negotiating skills at each stage of negotiation. It is clear that to have successful win-win negotiation outcomes the leading negotiator should put together a good team, with expert knowledge of product or conditions and negotiating skill, as well as possessing the attributes mentioned in the previous paragraph. The negotiator should also be able to determine authority limits, patience and observe negotiation ethics. No team disagreements concerning the business/project matters should be aired in front of counterparts during negotiations and professional conduct must prevail at all times. The findings of the study indicated that awareness of the practice of offering concessions regarding government tariff laws and price discounts that is in line with traditions in Tanzania. Concessions should not be made until all issues have been discussed, to avoid granting unnecessary benefits during negotiation that might be interpreted as bribery. This study concluded that it is important that marketers meet the requirements of business practices by sharing clear guidelines and policies regarding business practices, as this will lead to fruitful decisions. It was also found that negotiation behaviour improves when negotiators are willing to share information and agree that all communication must be in writing; marketers are more comfortable when there is a clear understanding of matters agreed upon, the choice of trading partners and that all trading agreements are written and a contract signed by all the parties, including governments where necessary. Marketers’ intentions are derived from the common interests of both parties and the negotiations should always take place in avenue that is suitable to both parties, conducted in fairness and offers must be reasonable and attainable with a positive outcome as the ultimate aim for both parties. This study reveals that negotiators insist on the use an agent or agents and sub-contractors to ensure mutually beneficial strategic business partnerships. However, when the role of the interest groups is explained to all participants, negotiation behaviour improves. It can also be concluded that negotiators allow interest groups to participate as team leaders and their number should be equal to the number of foreign negotiators, to ensure that marketers feel more at ease and comfortable to participate. An atmosphere based on bargaining power exerts a positive influence on the level of commitment among negotiating partners; and can be a predictor of the range of agreement as well as shape limits and priorities among dimensions of rivalry. However, it is important for marketers to express willingness to accept the terms of their counterpart’s bargaining zone regardless of non-profitable quotas at stake; identify areas of bargaining from foreign traders even if they are not attractive enough for local traders and are comfortable with the counterparts’ bargaining zone regarding fixed rates on exporting and importing quotas between trading partners to build trust among negotiators. In conclusion, it was found that negotiation behaviour has a positive influence on the level of commitment of trading partners. A positive business relationship is created on trust and a high-level of commitment which should be of great satisfaction to negotiating parties for future prospective negotiations.
- Full Text:
- Date Issued: 2012
- Authors: Burhan, Ahmad Mtengwa
- Date: 2012
- Subjects: Negotiation in business -- Tanzania , Business enterprises -- Tanzania , Export marketing -- Tanzania
- Language: English
- Type: Thesis , Doctoral , DBA
- Identifier: vital:9297 , http://hdl.handle.net/10948/d1013705
- Description: The success of international business depends on effective negotiations. Such negotiations do no happen in a vacuum, but usually in a specific environment that includes; time, surrounding, place, culture and people. The business environmental setting includes legal and political pluralism, currency fluctuations, foreign exchange, foreign government controls, bureaucracy, instability, change, ideological and cultural differences, as well as the influence of external stakeholders. These business negotiations environments can influence the behaviour of negotiation in global firms, impacting firms internationally. The reasons to negotiate on an international level may include considerations such as: choice of venue, culture to observe; and the outcome of the negotiation process. The aim of this study was to determine the influence of the international marketing environment, awareness of negotiation skill, interest groups and negotiation atmosphere on behaviour of marketers in a global firm. The study assessed the impact of negotiation behaviour on business agreements based on trust and certainty and level of commitment. The purpose of the study was to gauge the impact of negotiations behaviour pertaining to failure of business negotiations in Tanzania. In addition, the study endeavoured to determine the impact of environmental variables on the negotiation behaviour of marketers. The questionnaires used in the study comprised seven variables with statements linked to a five-point Likert-type interval scale varying from “strongly agree” to “strongly disagree. Self-administered questionnaires were used for data collection from global firms’ marketers and their management representatives; 323 questionnaires were collected from respondents. This study contributed to the literature on negotiation behaviour in a global firm and the perceptions of such global marketers in Tanzania. Many international companies in Tanzania find it difficult to formulate and implement a comprehensive business strategy; therefore, this study intends to equip international business managers with the leadership skills required. Based on the findings of this study, the negotiators and government are expected to play a major role in business negotiations to promote effective trade agreements despite limitations of political influence in the negotiation process. Political stability in a country enhances foreign business which in turn improves negotiation behaviour. A just legal system, with clear and unambiguous business guidelines and policies would benefit and promote local businesses and government representatives and negotiators in respect of international business negotiation behaviour. Reasonable tax and interest rates and fair business policies should improve international trade negotiations and business practices. In order to conduct successful international negotiations aspects such as culture, language differences, customs and traditions are important and should enjoy high priority. Aspects such as these mentioned influence the conducting and atmosphere and outcome of negotiations. The study reveals that the use of specialists and interpreters are imperative to guarantee understanding and successful outcomes. According to the findings negotiators should possess good negotiating skills to be able to steer the negotiation process through the different phases of negotiation that requires different negotiating skills at each stage of negotiation. It is clear that to have successful win-win negotiation outcomes the leading negotiator should put together a good team, with expert knowledge of product or conditions and negotiating skill, as well as possessing the attributes mentioned in the previous paragraph. The negotiator should also be able to determine authority limits, patience and observe negotiation ethics. No team disagreements concerning the business/project matters should be aired in front of counterparts during negotiations and professional conduct must prevail at all times. The findings of the study indicated that awareness of the practice of offering concessions regarding government tariff laws and price discounts that is in line with traditions in Tanzania. Concessions should not be made until all issues have been discussed, to avoid granting unnecessary benefits during negotiation that might be interpreted as bribery. This study concluded that it is important that marketers meet the requirements of business practices by sharing clear guidelines and policies regarding business practices, as this will lead to fruitful decisions. It was also found that negotiation behaviour improves when negotiators are willing to share information and agree that all communication must be in writing; marketers are more comfortable when there is a clear understanding of matters agreed upon, the choice of trading partners and that all trading agreements are written and a contract signed by all the parties, including governments where necessary. Marketers’ intentions are derived from the common interests of both parties and the negotiations should always take place in avenue that is suitable to both parties, conducted in fairness and offers must be reasonable and attainable with a positive outcome as the ultimate aim for both parties. This study reveals that negotiators insist on the use an agent or agents and sub-contractors to ensure mutually beneficial strategic business partnerships. However, when the role of the interest groups is explained to all participants, negotiation behaviour improves. It can also be concluded that negotiators allow interest groups to participate as team leaders and their number should be equal to the number of foreign negotiators, to ensure that marketers feel more at ease and comfortable to participate. An atmosphere based on bargaining power exerts a positive influence on the level of commitment among negotiating partners; and can be a predictor of the range of agreement as well as shape limits and priorities among dimensions of rivalry. However, it is important for marketers to express willingness to accept the terms of their counterpart’s bargaining zone regardless of non-profitable quotas at stake; identify areas of bargaining from foreign traders even if they are not attractive enough for local traders and are comfortable with the counterparts’ bargaining zone regarding fixed rates on exporting and importing quotas between trading partners to build trust among negotiators. In conclusion, it was found that negotiation behaviour has a positive influence on the level of commitment of trading partners. A positive business relationship is created on trust and a high-level of commitment which should be of great satisfaction to negotiating parties for future prospective negotiations.
- Full Text:
- Date Issued: 2012
Measuring the competitiveness of small, medium and micro enterprice contractors through the use of the register of contractors
- Gasa, Zanele Bridgette Nompumelelo
- Authors: Gasa, Zanele Bridgette Nompumelelo
- Date: 2012
- Subjects: Construction industry -- South Africa , Construction contracts -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9699 , http://hdl.handle.net/10948/d1014325
- Description: This research focuses on and summarises the methodology followed to demonstrate that the South African construction industry can use the Construction Registers Service, in particular the Register of Contractors, as a tool to measure the competitiveness of Small, Micro and Medium Enterprises (SMMEs). The Register of Contractors (RoC) was developed by the Construction Industry Development Board (cidb) in terms of the Construction Industry Development Board (cidb) Act 38 of 2000. As a tool, it was designed to offer a basis for sustainable constructor development, growth, improved delivery, performance and sustainable empowerment. It was also developed to be used by the construction industry to, inter alia, and provide statistical data which would enable the construction industry to better understand the contracting capacity in South Africa. Beyond providing the statistical data, the register of contractors was meant to be enhanced with functionalities that would measure the growth and performance of contractors as they apply business practices that improve their value offering to the construction industry as a whole. This research looks at how this tool can be used by the construction industry to measure the competitiveness of the contractors within the selected grades, with the intent of demonstrating the overall value of the RoC as a tool. The research undertaken looks at how the use of the RoC can measure the competitiveness of a targeted group of small contractors. The research limits itself to the entry levels of contractors registered with the cidb between grades 2 and 5 with a view to establish a benchmark for contractor competitiveness within those bands. The research further proves the correlation between contractor capability and the ‘ability’ to be competitive in growing their value proposition and businesses. The unit of study for the purposes of this research is at firm level drawing from a reflection on who is an active participant in the South African construction industry particularly as it pertains to the smaller contractors within the targeted group elucidated above. The focus of the research is on the efficacy of the RoC as a tool that identifies the areas needing targeted development to support SMMEs and the subsequent demonstration of improved business processes within that sector. The qualitative research methodology was followed through this study as its nature was such that there was no requirement to rely only entirely on statistics or numbers due to the articulated problem there needed to be a qualitative enquiry into data needed which would adequately land to a significant synthesis on the responses and arrive at suitable solutions to the identified problem. The qualitative research methodology followed by this study was used to gain insight into the construction SMMEs’ attitudes towards the sector within which they trade, their behaviours, their value systems [to the extent where this was possible], their concerns, their motivations and aspirations. All of these, the study concluded that they inform the business decisions which the SMMEs make. How structured information was collected and analysed provided a synthesis of themes and aided in extracting meaning. The main findings of the research were that there is no shared understanding within the local construction industry of what contractor competitiveness is and to what extent it would benefit both the industry and the SMME sector. As a result of this competitiveness could not be measured and there was no clarity as to what tools of measure could be used to forecast the capabilities of the industry. This research was focused on exploring how the RoC can be used to measure improved capability and competitiveness on the part of SMME contractors. The implications of these findings are that there would now be improved and measurable competitiveness allowing the contractors to bid for work both within their provincial regions but also outside of their geographical location and to measure their growth as they achieve higher grading statuses within the register of contractors (RoC). The efficacy of contractor development programmes would also improve as they go beyond enhancing contractor capacity but also include competence improvements, training for business acumen, improved capability and innovation. The conclusion is that South Africa’s construction industry could achieve sustainable development and growth as a result of SMME contractors whose competitiveness would have been measured through the use of the RoC tool. The main recommendation is that there be a clear understanding of competitiveness and what its benefits to the South African construction industry are whilst at the same time the RoC is acknowledged as the tool embedded with functionalities able to measure this competitiveness amongst graded contractors. The RoC would allow construction clients to not only measure contractor competitiveness but also that they may have an improved ability to measure the direct impacts of contractor development interventions. , Lolucubungulo lugxile ekubhekeni izimo ezinqala ngaphakathi komkhakha wezokwakha. Lubuka igalelo losonkontilaka abasebancane kulomkhakha ekuzithuthukiseni kanti futhi nemizamo eyenziwe uHulumeni endimeni edlalwe uhlu olushicilwelwe iBhodi yomkhakha wezokwakha (i-cidb). Umbhali walolucubungulo ukholelwa ekutheni loluhlu lungasetshenziswa hhayi kuphela ekuthuthikiseni ononkontilaka kodwa futhi ekwenzeni ukuthi bakhule kulo lona loluhlu baze bakwazi ukuthola amathuba angcono emisebenzi. Uhlu ekukhulunywa ngalo lapha lwashicilelwa i-cidb ngomgomo womthetho kaHulumeni we-Act 38 of 2000. Luyithuluzi elenzelwe ukuba likhulise umkhakha wezokwakha, lithuthukise osomabhizinisi abasebancane, likhuthaze imigomo efanelekile ekwakheni (improved delivery). Enye injongo yokushicilela lelithuluzi kwakuwukwenzela ukuthi kwaziwe inani labo osonkontilaka, ubulili babo nokuthi bagxile-phi ngokwezindawo zokusebenza. Konke loku kwakufanele ukuze uHulumeni kanye nabanye abaqashi bazi ukuthi uma kusikelwana ngemisebenzi bangaki na ononkontilaka abazokwazi ukufeza izidingo zemiphakathi esiphila kuyo? Lolucubungulo luzobheka ithuluzi elasungulwa umkhakha wokwakha ekutheni lingakwazi na ukudlondlobalisa osonkontilaka abasafufusa phakathi kwalemikhakha (grades) ababekwe kuyo? Kuzobhekwa futhi ubugugu balo lona lelithuluzi. Akuzoqxilwa kubo bonke osonkontilaka, kodwa kulabo abasabancane ngokwamabhizinisi abo ababekwe emazingeni kusukela ku-2 kuya ku-5 ngokoshicilelo le-cidb. Kuzobhekwa amakhono abo labosonkontilaka, kubhekwe futhi izinkomba ezingabadlondlobalisa ngokwamabhizinisi. Okunye okuhloswe yilolucubungulo ukubheka ukuthi umkhakha wezokwakha uyakwazi na ukukhiqiza amathuba anele isikhathi eside kwenzelwa osonkotilaka belu nokuthi uyakwazi na ukuqhubeka wakhe amathuba azokhuthaza ukukhula kwabo. Ekugcineni okufanele kufezwe yilolucubungulo wukuthi uhlu olushicilelwe losonkontilaka lungasiza ekukhuthazeni udlondlobalo losonkontilaka abancane.
- Full Text:
- Date Issued: 2012
- Authors: Gasa, Zanele Bridgette Nompumelelo
- Date: 2012
- Subjects: Construction industry -- South Africa , Construction contracts -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9699 , http://hdl.handle.net/10948/d1014325
- Description: This research focuses on and summarises the methodology followed to demonstrate that the South African construction industry can use the Construction Registers Service, in particular the Register of Contractors, as a tool to measure the competitiveness of Small, Micro and Medium Enterprises (SMMEs). The Register of Contractors (RoC) was developed by the Construction Industry Development Board (cidb) in terms of the Construction Industry Development Board (cidb) Act 38 of 2000. As a tool, it was designed to offer a basis for sustainable constructor development, growth, improved delivery, performance and sustainable empowerment. It was also developed to be used by the construction industry to, inter alia, and provide statistical data which would enable the construction industry to better understand the contracting capacity in South Africa. Beyond providing the statistical data, the register of contractors was meant to be enhanced with functionalities that would measure the growth and performance of contractors as they apply business practices that improve their value offering to the construction industry as a whole. This research looks at how this tool can be used by the construction industry to measure the competitiveness of the contractors within the selected grades, with the intent of demonstrating the overall value of the RoC as a tool. The research undertaken looks at how the use of the RoC can measure the competitiveness of a targeted group of small contractors. The research limits itself to the entry levels of contractors registered with the cidb between grades 2 and 5 with a view to establish a benchmark for contractor competitiveness within those bands. The research further proves the correlation between contractor capability and the ‘ability’ to be competitive in growing their value proposition and businesses. The unit of study for the purposes of this research is at firm level drawing from a reflection on who is an active participant in the South African construction industry particularly as it pertains to the smaller contractors within the targeted group elucidated above. The focus of the research is on the efficacy of the RoC as a tool that identifies the areas needing targeted development to support SMMEs and the subsequent demonstration of improved business processes within that sector. The qualitative research methodology was followed through this study as its nature was such that there was no requirement to rely only entirely on statistics or numbers due to the articulated problem there needed to be a qualitative enquiry into data needed which would adequately land to a significant synthesis on the responses and arrive at suitable solutions to the identified problem. The qualitative research methodology followed by this study was used to gain insight into the construction SMMEs’ attitudes towards the sector within which they trade, their behaviours, their value systems [to the extent where this was possible], their concerns, their motivations and aspirations. All of these, the study concluded that they inform the business decisions which the SMMEs make. How structured information was collected and analysed provided a synthesis of themes and aided in extracting meaning. The main findings of the research were that there is no shared understanding within the local construction industry of what contractor competitiveness is and to what extent it would benefit both the industry and the SMME sector. As a result of this competitiveness could not be measured and there was no clarity as to what tools of measure could be used to forecast the capabilities of the industry. This research was focused on exploring how the RoC can be used to measure improved capability and competitiveness on the part of SMME contractors. The implications of these findings are that there would now be improved and measurable competitiveness allowing the contractors to bid for work both within their provincial regions but also outside of their geographical location and to measure their growth as they achieve higher grading statuses within the register of contractors (RoC). The efficacy of contractor development programmes would also improve as they go beyond enhancing contractor capacity but also include competence improvements, training for business acumen, improved capability and innovation. The conclusion is that South Africa’s construction industry could achieve sustainable development and growth as a result of SMME contractors whose competitiveness would have been measured through the use of the RoC tool. The main recommendation is that there be a clear understanding of competitiveness and what its benefits to the South African construction industry are whilst at the same time the RoC is acknowledged as the tool embedded with functionalities able to measure this competitiveness amongst graded contractors. The RoC would allow construction clients to not only measure contractor competitiveness but also that they may have an improved ability to measure the direct impacts of contractor development interventions. , Lolucubungulo lugxile ekubhekeni izimo ezinqala ngaphakathi komkhakha wezokwakha. Lubuka igalelo losonkontilaka abasebancane kulomkhakha ekuzithuthukiseni kanti futhi nemizamo eyenziwe uHulumeni endimeni edlalwe uhlu olushicilwelwe iBhodi yomkhakha wezokwakha (i-cidb). Umbhali walolucubungulo ukholelwa ekutheni loluhlu lungasetshenziswa hhayi kuphela ekuthuthikiseni ononkontilaka kodwa futhi ekwenzeni ukuthi bakhule kulo lona loluhlu baze bakwazi ukuthola amathuba angcono emisebenzi. Uhlu ekukhulunywa ngalo lapha lwashicilelwa i-cidb ngomgomo womthetho kaHulumeni we-Act 38 of 2000. Luyithuluzi elenzelwe ukuba likhulise umkhakha wezokwakha, lithuthukise osomabhizinisi abasebancane, likhuthaze imigomo efanelekile ekwakheni (improved delivery). Enye injongo yokushicilela lelithuluzi kwakuwukwenzela ukuthi kwaziwe inani labo osonkontilaka, ubulili babo nokuthi bagxile-phi ngokwezindawo zokusebenza. Konke loku kwakufanele ukuze uHulumeni kanye nabanye abaqashi bazi ukuthi uma kusikelwana ngemisebenzi bangaki na ononkontilaka abazokwazi ukufeza izidingo zemiphakathi esiphila kuyo? Lolucubungulo luzobheka ithuluzi elasungulwa umkhakha wokwakha ekutheni lingakwazi na ukudlondlobalisa osonkontilaka abasafufusa phakathi kwalemikhakha (grades) ababekwe kuyo? Kuzobhekwa futhi ubugugu balo lona lelithuluzi. Akuzoqxilwa kubo bonke osonkontilaka, kodwa kulabo abasabancane ngokwamabhizinisi abo ababekwe emazingeni kusukela ku-2 kuya ku-5 ngokoshicilelo le-cidb. Kuzobhekwa amakhono abo labosonkontilaka, kubhekwe futhi izinkomba ezingabadlondlobalisa ngokwamabhizinisi. Okunye okuhloswe yilolucubungulo ukubheka ukuthi umkhakha wezokwakha uyakwazi na ukukhiqiza amathuba anele isikhathi eside kwenzelwa osonkotilaka belu nokuthi uyakwazi na ukuqhubeka wakhe amathuba azokhuthaza ukukhula kwabo. Ekugcineni okufanele kufezwe yilolucubungulo wukuthi uhlu olushicilelwe losonkontilaka lungasiza ekukhuthazeni udlondlobalo losonkontilaka abancane.
- Full Text:
- Date Issued: 2012
Mechanistic studies of unusual Miruta-Baylis-Hillman reactions
- Authors: Nyoni, Dubekile
- Date: 2012
- Subjects: Chemical reactions Benzaldehyde Acrylonitrile Methyl acrylate Coumarins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4400 , http://hdl.handle.net/10962/d1006692
- Description: This study has focussed on the application of synthetic, kinetic and exploratory theoretical methods in elucidating the reaction mechanisms of four Morita-Baylis-Hillman (MBH) type reactions, viz, i) the reactions of the disulfide 2,2'-dithiodibenzaldehyde with various activated alkenes in the presence of DBU and Ph₃P, ii) the reactions of chromone-3-carbaldehydes with MVK, iii) the reactions of chromone-2-carbaldehydes with acrylonitrile and iv) with methyl acrylate. Attention has also been given to the origin of the observed regioselectivity in Michaelis-Arbuzov reactions of 3-(halomethyl)coumarins. Cleavage of the sulfur-sulfur bond of aryl and heteroaryl disulfides by the nitrogen nucleophile DBU has been demonstrated, and a dramatic increase in the rate of tandem MBH and disulfide cleavage reactions of 2,2'-dithiodibenzaldehyde with the activated alkenes, MVK, EVK, acrylonitrile, methyl acrylate and tert-butyl acrylate has been achieved through the use of the dual organo-catalyst system, DBU-Ph₃P – an improvement accompanied by an increase in the yields of the isolated products. Detailed NMR-based kinetic studies have been conducted on the DBU-catalysed reactions of 2,2'-dithiodibenzaldehyde with MVK and methyl acrylate, and a theoretical kinetic model has been developed and complementary computational studies using Gaussian 03, at the DFT-B3LYP/6-31G(d) level of theory have provided valuable insights into the mechanism of these complex transformations. Reactions of chromone-3-carbaldehydes with MVK to afford chromone dimers and tricyclic products have been repeated, and a novel, intermediate MBH adduct has been isolated. The mechanisms of the competing pathways have been elucidated by DFT calculations and the development of a detailed theoretical kinetic model has ensued. Unusual transformations in MBH-type reactions of chromone-2-carbaldehydes with acrylonitrile and methyl acrylate have been explored and the structures of the unexpected products have been established using 1- and 2-D NMR, HRMS and X-ray crystallographic techniques. Attention has also been given to the synthesis of 3-(halomethyl)coumarins via the MBH reaction, and their subsequent Michaelis-Arbuzov reactions with triethyl phosphite. An exploratory study of the kinetics of the phosphonation reaction has been undertaken and the regio-selectivity of nucleophilic attack at the 4- and 1'-positions in the 3-chloro- and 3-(iodomethyl)coumarins has been investigated by calculating Mulliken charges, LUMO surfaces and Fukui condensed local softness functions.
- Full Text:
- Date Issued: 2012
- Authors: Nyoni, Dubekile
- Date: 2012
- Subjects: Chemical reactions Benzaldehyde Acrylonitrile Methyl acrylate Coumarins
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4400 , http://hdl.handle.net/10962/d1006692
- Description: This study has focussed on the application of synthetic, kinetic and exploratory theoretical methods in elucidating the reaction mechanisms of four Morita-Baylis-Hillman (MBH) type reactions, viz, i) the reactions of the disulfide 2,2'-dithiodibenzaldehyde with various activated alkenes in the presence of DBU and Ph₃P, ii) the reactions of chromone-3-carbaldehydes with MVK, iii) the reactions of chromone-2-carbaldehydes with acrylonitrile and iv) with methyl acrylate. Attention has also been given to the origin of the observed regioselectivity in Michaelis-Arbuzov reactions of 3-(halomethyl)coumarins. Cleavage of the sulfur-sulfur bond of aryl and heteroaryl disulfides by the nitrogen nucleophile DBU has been demonstrated, and a dramatic increase in the rate of tandem MBH and disulfide cleavage reactions of 2,2'-dithiodibenzaldehyde with the activated alkenes, MVK, EVK, acrylonitrile, methyl acrylate and tert-butyl acrylate has been achieved through the use of the dual organo-catalyst system, DBU-Ph₃P – an improvement accompanied by an increase in the yields of the isolated products. Detailed NMR-based kinetic studies have been conducted on the DBU-catalysed reactions of 2,2'-dithiodibenzaldehyde with MVK and methyl acrylate, and a theoretical kinetic model has been developed and complementary computational studies using Gaussian 03, at the DFT-B3LYP/6-31G(d) level of theory have provided valuable insights into the mechanism of these complex transformations. Reactions of chromone-3-carbaldehydes with MVK to afford chromone dimers and tricyclic products have been repeated, and a novel, intermediate MBH adduct has been isolated. The mechanisms of the competing pathways have been elucidated by DFT calculations and the development of a detailed theoretical kinetic model has ensued. Unusual transformations in MBH-type reactions of chromone-2-carbaldehydes with acrylonitrile and methyl acrylate have been explored and the structures of the unexpected products have been established using 1- and 2-D NMR, HRMS and X-ray crystallographic techniques. Attention has also been given to the synthesis of 3-(halomethyl)coumarins via the MBH reaction, and their subsequent Michaelis-Arbuzov reactions with triethyl phosphite. An exploratory study of the kinetics of the phosphonation reaction has been undertaken and the regio-selectivity of nucleophilic attack at the 4- and 1'-positions in the 3-chloro- and 3-(iodomethyl)coumarins has been investigated by calculating Mulliken charges, LUMO surfaces and Fukui condensed local softness functions.
- Full Text:
- Date Issued: 2012
Media and agriculture in Africa : a case study of agriculture radio programming in Malawi
- Authors: Manda, Levison Zeleza
- Date: 2012
- Subjects: Radio in agriculture -- Malawi , Communication -- Agriculture -- Malawi
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8434 , http://hdl.handle.net/10948/d1020925
- Description: This thesis argues that although participatory communication for development has been extolled to be more effective than the monologic or top-down communication approaches associated with the modernization development paradigm, its influence in making Malawian smallholder farmers adopt radio-mediated innovations and technologies seems to be minimal and ought to be reconsidered for more effective communication for development models. The study used mostly qualitative methodology, with focus group discussions, key informant interviews, and a semi-structured questionnaire to gather verbal and statistical from the primary beneficiaries in order data to understand why three mass media interventions in Malawi had similar effects when only one of them was strictly participatory. It found, inter alia, that in two sites food security was the overriding factor that influenced the community members to adopt radio messages while in the third the participants were mostly driven by the desire to earn money, essentially because the area is food-secure. Thus, participation in radio production was found not to have any significant role in the acceptance and adoption of radio-mediated innovations by the farming communities. Based on the above findings, the study recommends a) an integrated communication for development (IC4D) model that combines top-down information dissemination techniques and participatory communication approaches since the two reinforce more than they oppose each other, and b) the formation of a Communication for Development (C4D) pool fund in Malawi to finance C4D activities. The C4D pool fund is theorised to be resourced by the Malawi government departments, local farmers ‘organisations, international NGOs, and UN bodies such as UNICEF, WHO, and the FAO.
- Full Text:
- Date Issued: 2012
- Authors: Manda, Levison Zeleza
- Date: 2012
- Subjects: Radio in agriculture -- Malawi , Communication -- Agriculture -- Malawi
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8434 , http://hdl.handle.net/10948/d1020925
- Description: This thesis argues that although participatory communication for development has been extolled to be more effective than the monologic or top-down communication approaches associated with the modernization development paradigm, its influence in making Malawian smallholder farmers adopt radio-mediated innovations and technologies seems to be minimal and ought to be reconsidered for more effective communication for development models. The study used mostly qualitative methodology, with focus group discussions, key informant interviews, and a semi-structured questionnaire to gather verbal and statistical from the primary beneficiaries in order data to understand why three mass media interventions in Malawi had similar effects when only one of them was strictly participatory. It found, inter alia, that in two sites food security was the overriding factor that influenced the community members to adopt radio messages while in the third the participants were mostly driven by the desire to earn money, essentially because the area is food-secure. Thus, participation in radio production was found not to have any significant role in the acceptance and adoption of radio-mediated innovations by the farming communities. Based on the above findings, the study recommends a) an integrated communication for development (IC4D) model that combines top-down information dissemination techniques and participatory communication approaches since the two reinforce more than they oppose each other, and b) the formation of a Communication for Development (C4D) pool fund in Malawi to finance C4D activities. The C4D pool fund is theorised to be resourced by the Malawi government departments, local farmers ‘organisations, international NGOs, and UN bodies such as UNICEF, WHO, and the FAO.
- Full Text:
- Date Issued: 2012
Megaherbivores in succulent thicket: resource use and implications
- Authors: Landman, Marietjie
- Date: 2012
- Subjects: Elephants , African elephant , Black rhinoceros , Succulent plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10689 , http://hdl.handle.net/10948/d1007956 , Elephants , African elephant , Black rhinoceros , Succulent plants
- Description: This study aims to develop a predictive understanding of the resource use, impacts and interactions of elephant Loxodonta africana and black rhinoceros Diceros bicornis in the succulent thickets of the Eastern Cape, South Africa. While these megaherbivores typically dominate the biomass, elephant are more abundant, such that their impacts off-set that of all other herbivores. Consequently, this thesis has three main foci: first, developing a mechanistic understanding of the influences of elephant; second, developing predictive insights into elephant impacts on plant communities; finally, an understanding of the knockon-effects of the impacts for coexisting rhinoceros. Thus, by documenting the diet and dietary preferences of elephant, I firstly show that only about 18 percent of the species previously thought vulnerable to herbivory, occur in the diet. This refutes the generally held belief that elephant herbivory is the primary driver of decline among plants, and emphasizes the likely contribution of other mechanisms (e.g. trampling, knock-on-effects, etc.). Thus, the accurate prediction of the impacts caused by elephant requires an understanding of previously marginalized mechanisms. From here, I quantify >50 years of impacts on the thicket shrub community and test their spatial and temporal extent near water. I confirm the vulnerability of thicket to transformation (particularly near water) as the accumulated influences of elephant reduce community composition and structure, and predict that these impacts will eventually bring about landscape-level degradation and a significant loss of biodiversity. Importantly, results show an uneven distribution of effects between elements of this community: from community composition and structure, to the structure of individual canopy species and ecological functioning. While these findings confound our interpretation of the extent of the impacts, it demonstrates the importance of explicitly recognizing biodiversity and heterogeneity for the conservation management of elephant. Finally, I test the consequences of the impacts for coexisting rhinoceros. While I show that this causes rhinoceros to change their foraging strategies in the presence of elephant at high densities, I also show that elephant may facilitate access to food for rhinoceros at reduced densities. These findings indicate the importance of elephant in driving the structure and composition of the thicket shrub community and the consequences of this for coexisting large herbivores. Thus, developing a predictive understanding of the spatial and temporal variations of elephant impacts between elements of biodiversity and the mechanisms driving these changes are key to their management. This implies that the effective conservation management of elephant can only be achieved through the careful, scientific design of monitoring programmes.
- Full Text:
- Date Issued: 2012
- Authors: Landman, Marietjie
- Date: 2012
- Subjects: Elephants , African elephant , Black rhinoceros , Succulent plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10689 , http://hdl.handle.net/10948/d1007956 , Elephants , African elephant , Black rhinoceros , Succulent plants
- Description: This study aims to develop a predictive understanding of the resource use, impacts and interactions of elephant Loxodonta africana and black rhinoceros Diceros bicornis in the succulent thickets of the Eastern Cape, South Africa. While these megaherbivores typically dominate the biomass, elephant are more abundant, such that their impacts off-set that of all other herbivores. Consequently, this thesis has three main foci: first, developing a mechanistic understanding of the influences of elephant; second, developing predictive insights into elephant impacts on plant communities; finally, an understanding of the knockon-effects of the impacts for coexisting rhinoceros. Thus, by documenting the diet and dietary preferences of elephant, I firstly show that only about 18 percent of the species previously thought vulnerable to herbivory, occur in the diet. This refutes the generally held belief that elephant herbivory is the primary driver of decline among plants, and emphasizes the likely contribution of other mechanisms (e.g. trampling, knock-on-effects, etc.). Thus, the accurate prediction of the impacts caused by elephant requires an understanding of previously marginalized mechanisms. From here, I quantify >50 years of impacts on the thicket shrub community and test their spatial and temporal extent near water. I confirm the vulnerability of thicket to transformation (particularly near water) as the accumulated influences of elephant reduce community composition and structure, and predict that these impacts will eventually bring about landscape-level degradation and a significant loss of biodiversity. Importantly, results show an uneven distribution of effects between elements of this community: from community composition and structure, to the structure of individual canopy species and ecological functioning. While these findings confound our interpretation of the extent of the impacts, it demonstrates the importance of explicitly recognizing biodiversity and heterogeneity for the conservation management of elephant. Finally, I test the consequences of the impacts for coexisting rhinoceros. While I show that this causes rhinoceros to change their foraging strategies in the presence of elephant at high densities, I also show that elephant may facilitate access to food for rhinoceros at reduced densities. These findings indicate the importance of elephant in driving the structure and composition of the thicket shrub community and the consequences of this for coexisting large herbivores. Thus, developing a predictive understanding of the spatial and temporal variations of elephant impacts between elements of biodiversity and the mechanisms driving these changes are key to their management. This implies that the effective conservation management of elephant can only be achieved through the careful, scientific design of monitoring programmes.
- Full Text:
- Date Issued: 2012
Mesozooplankton dynamics in a biogeographical transition zone estuary
- Deyzel, (Shaun) Herklaas Phillipus
- Authors: Deyzel, (Shaun) Herklaas Phillipus
- Date: 2012
- Subjects: Marine zooplankton -- South Africa , Benthos -- South Africa , Estuarine ecology -- South Africa , Mangrove forests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10687 , http://hdl.handle.net/10948/d1007901 , Marine zooplankton -- South Africa , Benthos -- South Africa , Estuarine ecology -- South Africa , Mangrove forests
- Description: This thesis presents the first intensive community-level investigation of the mesozooplankton from a biogeographical transition zone estuary. The Mgazana Estuary is located along a rural, semi-undeveloped part of South Africa’s east coast, believed to represent a transition zone between the subtropical and warm-temperate biogeographical zones. The research represented in this thesis involves data collected over a five year period between 2002 and 2006, with additional data collection made in 2008. The study focussed on five areas of investigation, the first of which investigated the physico-chemical dynamics of the Mgazana Estuary. The Mgazana Estuary exhibited marked vertical, horizontal and regional structures in the hydrological environment. Prominent vertical and horizontal stratification characterised summer months. A substantial turbidity front was observed in the lower estuary during summer and winter. The upper estuary was marked by considerable variation in multiple variables but especially salinity. These structures appeared to have shifted in position over the horizontal plane, which was attributed to variation in freshwater flow. The second study focused on the spatial dynamics of mesozooplankton in the Mgazana Estuary. The zooplankton was rich and in terms of composition typical of mangrove systems. The Copepoda were dominant, numerically and in terms of taxonomic representation. Calanoids Acartiella natalensis and Pseudodiaptomus hessei characterised middle and upper reaches in summer and mostly upper reaches in winter. On community level, a highly structured assemblage arrangement was observed during summer and winter months. These trends were further scrutinised under the theoretical framework of ecological boundaries. In so doing, an agreeable spatial association emerged between specific assemblages and their environments. These trends were concluded to reflect ecoclinal as well as ecotonal properties, the latter describing interactions over narrow spatial bands of marked changes in turbidity. The third study investigated flooding events as short-lived extreme meteorological events and the influence on zooplankton. Within this regard, second-stage multivariate statistics was used to assess year-to-year variability in assemblage structures on whole-system and regional scales. The impact of two major flooding events that flushed the estuary some days prior to sampling could clearly be elucidated. Flooding emerged as a significant source of inter-annual variability in the zooplankton of the Mgazana Estuary. Second-stage multivariate analysis proved to be an effective analytical strategy for investigating inter-annual variability in species assemblage structures. Results from the preceding study prompted a detailed investigation into the spatio-temporal dynamics of Acartiella natalensis, the most important zooplankton species of the system aimed at elucidating flood responses. Acartiella natalensis showed indication of temporal arrest in association with flooding events in a similar fashion as is observed in seasonal variation trends in estuaries towards its geographical distribution limit south of the study area. It was concluded that A. natalensis was severely affected by floods and the possibility exist for entrainment of entire populations from the estuary during flooding events. The final study tested the hypothesis of post-flood propagation from a resting egg bank in the sediments of the Mgazana Estuary. Preliminary data revealed that numerous eggs were present in the sediments. Nauplii hatched from eggs under laboratory conditions were identified as belonging to the family Acartiidae. The preliminary mode of diapause is presented as a schematic model, emphasising the role of freshwater flow and specific environmental variables. This was the first discovery of resting eggs from a subtropical estuary from South Africa. It is hoped that the findings of this study would give rise to new research initiatives investigating the importance of resting stages in estuarine and coastal Copepoda species and the role such reproductive strategies may play in estuarine functioning.
- Full Text:
- Date Issued: 2012
- Authors: Deyzel, (Shaun) Herklaas Phillipus
- Date: 2012
- Subjects: Marine zooplankton -- South Africa , Benthos -- South Africa , Estuarine ecology -- South Africa , Mangrove forests
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10687 , http://hdl.handle.net/10948/d1007901 , Marine zooplankton -- South Africa , Benthos -- South Africa , Estuarine ecology -- South Africa , Mangrove forests
- Description: This thesis presents the first intensive community-level investigation of the mesozooplankton from a biogeographical transition zone estuary. The Mgazana Estuary is located along a rural, semi-undeveloped part of South Africa’s east coast, believed to represent a transition zone between the subtropical and warm-temperate biogeographical zones. The research represented in this thesis involves data collected over a five year period between 2002 and 2006, with additional data collection made in 2008. The study focussed on five areas of investigation, the first of which investigated the physico-chemical dynamics of the Mgazana Estuary. The Mgazana Estuary exhibited marked vertical, horizontal and regional structures in the hydrological environment. Prominent vertical and horizontal stratification characterised summer months. A substantial turbidity front was observed in the lower estuary during summer and winter. The upper estuary was marked by considerable variation in multiple variables but especially salinity. These structures appeared to have shifted in position over the horizontal plane, which was attributed to variation in freshwater flow. The second study focused on the spatial dynamics of mesozooplankton in the Mgazana Estuary. The zooplankton was rich and in terms of composition typical of mangrove systems. The Copepoda were dominant, numerically and in terms of taxonomic representation. Calanoids Acartiella natalensis and Pseudodiaptomus hessei characterised middle and upper reaches in summer and mostly upper reaches in winter. On community level, a highly structured assemblage arrangement was observed during summer and winter months. These trends were further scrutinised under the theoretical framework of ecological boundaries. In so doing, an agreeable spatial association emerged between specific assemblages and their environments. These trends were concluded to reflect ecoclinal as well as ecotonal properties, the latter describing interactions over narrow spatial bands of marked changes in turbidity. The third study investigated flooding events as short-lived extreme meteorological events and the influence on zooplankton. Within this regard, second-stage multivariate statistics was used to assess year-to-year variability in assemblage structures on whole-system and regional scales. The impact of two major flooding events that flushed the estuary some days prior to sampling could clearly be elucidated. Flooding emerged as a significant source of inter-annual variability in the zooplankton of the Mgazana Estuary. Second-stage multivariate analysis proved to be an effective analytical strategy for investigating inter-annual variability in species assemblage structures. Results from the preceding study prompted a detailed investigation into the spatio-temporal dynamics of Acartiella natalensis, the most important zooplankton species of the system aimed at elucidating flood responses. Acartiella natalensis showed indication of temporal arrest in association with flooding events in a similar fashion as is observed in seasonal variation trends in estuaries towards its geographical distribution limit south of the study area. It was concluded that A. natalensis was severely affected by floods and the possibility exist for entrainment of entire populations from the estuary during flooding events. The final study tested the hypothesis of post-flood propagation from a resting egg bank in the sediments of the Mgazana Estuary. Preliminary data revealed that numerous eggs were present in the sediments. Nauplii hatched from eggs under laboratory conditions were identified as belonging to the family Acartiidae. The preliminary mode of diapause is presented as a schematic model, emphasising the role of freshwater flow and specific environmental variables. This was the first discovery of resting eggs from a subtropical estuary from South Africa. It is hoped that the findings of this study would give rise to new research initiatives investigating the importance of resting stages in estuarine and coastal Copepoda species and the role such reproductive strategies may play in estuarine functioning.
- Full Text:
- Date Issued: 2012