Local economic development: a case study of the Blue Crane Route Municipality, Eastern Cape, South Africa
- Authors: Boose, Refuoe
- Date: 2010
- Subjects: Local government -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape , Rural-urban relations -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Geography)
- Identifier: vital:11509 , http://hdl.handle.net/10353/248 , Local government -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape , Rural-urban relations -- South Africa -- Eastern Cape
- Description: Local economic development (LED) in the countries of the North is a voluntary activity of local government, in South Africa it is a mandatory activity. The purpose of LED is to build the capacity of a local area to improve its economic future and the quality of life for all. While local governments in South Africa are currently engaged with the concept of LED which is seen as a tool through which to achieve sustainable development, it is now recognized that there exists economic, social and environmental interdependence between rural and urban areas and a need for a balanced and mutually supportive approach to development of the rural and urban areas. Adopting the Rural-Urban, Economic and Enterprise Development (RUEED) concept, this study highlights the challenges and development problems experienced by the deep rural and urban communities in the implementation of LED activities within the Blue Crane Route Municipality (BCRM) due to the lack of social, economic and environmental sustainability and rural-urban linkages. This study located in the Blue Crane Route Municipality in the Eastern Cape, seeks to investigate and recommend a map or strategies linking together the urban communities with the poorer neighbourhoods in LED activities. The intensive research design that incorporates the case study method was used to achieve the objectives of this study. The empirical findings of the research indicate that the concept of rural-urban linkages is not an adopted strategy in implementing development programmes resulting in deep rural communities being excluded in LED activities initiated within the Blue Crane Route Municipality. The findings also reveal that the creation of employment opportunities and improvement in the standard of living are important dimensions of LED and rural-urban linkages. This study therefore recommends the adoption of a new perspective referred to as the rural-urban linkages for LED and the consideration of economic, social and environmental complementaries that exist between rural and urban areas in the Blue Crane Route Municipality. The study further indicates that it is critical that the LED policy and interventions reflect the existing patterns of interactions between the rural and urban areas of the Municipality.
- Full Text:
- Date Issued: 2010
- Authors: Boose, Refuoe
- Date: 2010
- Subjects: Local government -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape , Rural-urban relations -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Geography)
- Identifier: vital:11509 , http://hdl.handle.net/10353/248 , Local government -- South Africa -- Eastern Cape , Sustainable development -- South Africa -- Eastern Cape , Rural-urban relations -- South Africa -- Eastern Cape
- Description: Local economic development (LED) in the countries of the North is a voluntary activity of local government, in South Africa it is a mandatory activity. The purpose of LED is to build the capacity of a local area to improve its economic future and the quality of life for all. While local governments in South Africa are currently engaged with the concept of LED which is seen as a tool through which to achieve sustainable development, it is now recognized that there exists economic, social and environmental interdependence between rural and urban areas and a need for a balanced and mutually supportive approach to development of the rural and urban areas. Adopting the Rural-Urban, Economic and Enterprise Development (RUEED) concept, this study highlights the challenges and development problems experienced by the deep rural and urban communities in the implementation of LED activities within the Blue Crane Route Municipality (BCRM) due to the lack of social, economic and environmental sustainability and rural-urban linkages. This study located in the Blue Crane Route Municipality in the Eastern Cape, seeks to investigate and recommend a map or strategies linking together the urban communities with the poorer neighbourhoods in LED activities. The intensive research design that incorporates the case study method was used to achieve the objectives of this study. The empirical findings of the research indicate that the concept of rural-urban linkages is not an adopted strategy in implementing development programmes resulting in deep rural communities being excluded in LED activities initiated within the Blue Crane Route Municipality. The findings also reveal that the creation of employment opportunities and improvement in the standard of living are important dimensions of LED and rural-urban linkages. This study therefore recommends the adoption of a new perspective referred to as the rural-urban linkages for LED and the consideration of economic, social and environmental complementaries that exist between rural and urban areas in the Blue Crane Route Municipality. The study further indicates that it is critical that the LED policy and interventions reflect the existing patterns of interactions between the rural and urban areas of the Municipality.
- Full Text:
- Date Issued: 2010
Localisation of Theiler's murine encephalomyelitis virus protein 2C to the golgi apparatus using antibodies generated against a peptide region:
- Jauka, Tembisa, Mutsvunguma, Lorraine Z, Boshoff, Aileen, Edkins, Adrienne L, Knox, Caroline M
- Authors: Jauka, Tembisa , Mutsvunguma, Lorraine Z , Boshoff, Aileen , Edkins, Adrienne L , Knox, Caroline M
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165074 , vital:41206 , DOI: 10.1016/j.jviromet.2010.05.009
- Description: The picornavirus 2C protein is highly conserved and indispensible for virus replication. Polyclonal antibodies against Theiler's murine encephalomyelitis virus (TMEV) 2C protein were generated by immunisation of rabbits with a peptide comprising amino acids 31–210 of the protein. Antibodies were used to investigate the localisation of 2C in infected cells by indirect immunofluorescence and confocal microscopy. Analysis of infected cells revealed that the distribution of 2C changed during infection.
- Full Text:
- Date Issued: 2010
- Authors: Jauka, Tembisa , Mutsvunguma, Lorraine Z , Boshoff, Aileen , Edkins, Adrienne L , Knox, Caroline M
- Date: 2010
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/165074 , vital:41206 , DOI: 10.1016/j.jviromet.2010.05.009
- Description: The picornavirus 2C protein is highly conserved and indispensible for virus replication. Polyclonal antibodies against Theiler's murine encephalomyelitis virus (TMEV) 2C protein were generated by immunisation of rabbits with a peptide comprising amino acids 31–210 of the protein. Antibodies were used to investigate the localisation of 2C in infected cells by indirect immunofluorescence and confocal microscopy. Analysis of infected cells revealed that the distribution of 2C changed during infection.
- Full Text:
- Date Issued: 2010
Locating my media DNA
- Authors: Chiwota,Elijah
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454775 , vital:75375 , https://hdl.handle.net/10520/EJC139351
- Description: Imagine after working for seven years as a magazine writer and editor, Rhodes University offers you a place to study for an MA and your first assignment is a critique of a Stuart Hall article.
- Full Text:
- Date Issued: 2010
- Authors: Chiwota,Elijah
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/454775 , vital:75375 , https://hdl.handle.net/10520/EJC139351
- Description: Imagine after working for seven years as a magazine writer and editor, Rhodes University offers you a place to study for an MA and your first assignment is a critique of a Stuart Hall article.
- Full Text:
- Date Issued: 2010
Macrobenthic community structure across an inter- and subtidal gradient in a mangrove estuary
- Authors: Groenewald, Christoff J
- Date: 2010
- Subjects: Mangrove ecology -- South Africa -- Mngazana Estuary , Estuarine ecology -- South Africa -- Mngazana Estuary , Benthos -- South Africa -- Mngazana Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10695 , http://hdl.handle.net/10948/1240 , Mangrove ecology -- South Africa -- Mngazana Estuary , Estuarine ecology -- South Africa -- Mngazana Estuary , Benthos -- South Africa -- Mngazana Estuary
- Description: Macrozoobenthic community structure and composition was investigated along a subtidal-intertidal gradient in the Mngazana Estuary. Six transects were sampled between the spring high water mark (HWST) and the bottom of the river channel in the lower estuary. Fifteen replicate samples were collected along each transect using a Van Veen type grab (211 cm2 bite) during each of three sampling sessions. Samples were sieved through a 500 μm mesh bag and the invertebrates stored in bottles for further analysis in the laboratory. Additional grab samples were collected for sediment particle size analysis and organic matter. Physical variables measured at each transect included: salinity, temperature, dissolved oxygen, depth, pH, percentage mud, organic content and turbidity. Sediment compactness was measured at all intertidal transects and additional sediment samples were collected at mid shore and high shore transects for percentage water content analysis. A total of 104 species were recorded along the intertidal-subtidal gradient in the sampling area. Species richness was higher in the subtidal zone compared to the intertidal zone and polychaetes numerically dominated the macrozoobenthic community at most transects, during all three sessions. At high shore transects the community was characterised by having fewer species, consisting mostly of brachyurans, polychaetes and gastropods. Shannon diversity index (H’) was generally higher for subtidal transects (x¯ = 2.3; range: 2.8 to 1) than for intertidal transects (x¯ = 1.4; range: 2.2 to 0.6) indicating that the distribution of individuals among species in the intertidal zone experienced greater variability. Results for Hill’s numbers followed the same trend as Shannon diversity with subtidal communities mostly consisting of abundant species followed by very abundant species. Intertidal communities generally exhibited lower numbers of abundant and very abundant species. Sedimentary characteristics played a major role in structuring benthic communities in comparison to other physico-chemical variables. Organic content and mud content of the substrate were identified as important factors influencing community patterns observed along the subtidal-intertidal gradient. In addition, sediment compactness and water content of the substrate was found to influence intertidal community structure. Subtidal community structure possibly had a greater dependence on seasonal variations in abiotic and/or biotic factors. Cluster dendrograms used in conjunction with MDS ordination mapping revealed that macrozoobenthic communities were generally distinct between high shore intertidal transects iii and subtidal transects. Most species exhibited a broad spatial distribution along the subtidal-intertidal gradient with mid and high shore transects being the exception. Most species also exhibited marked shifts in abundance and this was especially noticeable at the transition between the subtidal and intertidal zone. Two polychaete species, Prionospio sexoculata and Capitella capitata, were very abundant species and featured amongst the most numerically dominant species collected during each sampling session.
- Full Text:
- Date Issued: 2010
- Authors: Groenewald, Christoff J
- Date: 2010
- Subjects: Mangrove ecology -- South Africa -- Mngazana Estuary , Estuarine ecology -- South Africa -- Mngazana Estuary , Benthos -- South Africa -- Mngazana Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10695 , http://hdl.handle.net/10948/1240 , Mangrove ecology -- South Africa -- Mngazana Estuary , Estuarine ecology -- South Africa -- Mngazana Estuary , Benthos -- South Africa -- Mngazana Estuary
- Description: Macrozoobenthic community structure and composition was investigated along a subtidal-intertidal gradient in the Mngazana Estuary. Six transects were sampled between the spring high water mark (HWST) and the bottom of the river channel in the lower estuary. Fifteen replicate samples were collected along each transect using a Van Veen type grab (211 cm2 bite) during each of three sampling sessions. Samples were sieved through a 500 μm mesh bag and the invertebrates stored in bottles for further analysis in the laboratory. Additional grab samples were collected for sediment particle size analysis and organic matter. Physical variables measured at each transect included: salinity, temperature, dissolved oxygen, depth, pH, percentage mud, organic content and turbidity. Sediment compactness was measured at all intertidal transects and additional sediment samples were collected at mid shore and high shore transects for percentage water content analysis. A total of 104 species were recorded along the intertidal-subtidal gradient in the sampling area. Species richness was higher in the subtidal zone compared to the intertidal zone and polychaetes numerically dominated the macrozoobenthic community at most transects, during all three sessions. At high shore transects the community was characterised by having fewer species, consisting mostly of brachyurans, polychaetes and gastropods. Shannon diversity index (H’) was generally higher for subtidal transects (x¯ = 2.3; range: 2.8 to 1) than for intertidal transects (x¯ = 1.4; range: 2.2 to 0.6) indicating that the distribution of individuals among species in the intertidal zone experienced greater variability. Results for Hill’s numbers followed the same trend as Shannon diversity with subtidal communities mostly consisting of abundant species followed by very abundant species. Intertidal communities generally exhibited lower numbers of abundant and very abundant species. Sedimentary characteristics played a major role in structuring benthic communities in comparison to other physico-chemical variables. Organic content and mud content of the substrate were identified as important factors influencing community patterns observed along the subtidal-intertidal gradient. In addition, sediment compactness and water content of the substrate was found to influence intertidal community structure. Subtidal community structure possibly had a greater dependence on seasonal variations in abiotic and/or biotic factors. Cluster dendrograms used in conjunction with MDS ordination mapping revealed that macrozoobenthic communities were generally distinct between high shore intertidal transects iii and subtidal transects. Most species exhibited a broad spatial distribution along the subtidal-intertidal gradient with mid and high shore transects being the exception. Most species also exhibited marked shifts in abundance and this was especially noticeable at the transition between the subtidal and intertidal zone. Two polychaete species, Prionospio sexoculata and Capitella capitata, were very abundant species and featured amongst the most numerically dominant species collected during each sampling session.
- Full Text:
- Date Issued: 2010
Macrophyte phenology in a temporarily open/closed Estuary compared with a permanently open Estuary
- Authors: Vromans, Deborah Claire
- Date: 2010
- Subjects: Estuarine ecology -- South Africa -- East Kleinemonde Estuary , Aquatic plants -- South Africa -- East Kleinemonde Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10612 , http://hdl.handle.net/10948/1393 , Estuarine ecology -- South Africa -- East Kleinemonde Estuary , Aquatic plants -- South Africa -- East Kleinemonde Estuary
- Description: Temporarily open/closed estuaries (TOCEs) are unpredictable environments that change in response to mouth condition, which is influenced by freshwater flooding or sea storm surges. The aim of the study was to determine whether macrophyte phenology in a TOCE was event driven rather than cyclically predictable and if it differed from permanently open estuaries (POEs). Macrophyte growth and flowering phenology in response to environmental conditions was investigated in the East Kleinemonde Estuary (TOCE) and the Kowie Estuary (POE) along the eastern coastline of South Africa. The lack of freshwater flooding due to low rainfall coupled with several overwash events resulted in a prolonged period of mouth closure from September 2008 to the end of this study period in 2010. This in turn caused the inundation of the supratidal and intertidal habitats, high water level (> 1.57 m amsl) and high salinity (30 - 42 ppt) in the TOCE. Principle Components Analysis showed that high water level and reduced sediments were the most significant environmental factors affecting macrophyte phenology. Macrophyte phenology in the POE was primarily driven by temperature, sediment redox potential and salinity. The saline high water level and reduced sediment significantly reduced macrophyte cover in all habitats in the TOCE. Macrophytes in the POE maintained high cover abundance due to seasonal re-growth compared to the TOCE where cover declined over the sampling period due to the high water level. Subsequent to water level dropping by as little as 11 - 20 cm in the TOCE, the intertidal species Sarcocornia tegetaria and Salicornia meyeriana completed their life-cycles and produced viable seeds within four and three months of germinating respectively. In contrast, the Sarcocornia hybrid and S. meyeriana in the POE took longer to complete their life-cycles, namely seven and nine months respectively, while S. tegataria did not germinate in situ but reproduced vegetatively despite producing seed. In the TOCE, the submerged species Ruppia cirrhosa and Chara vulgaris completed their life-cycles within five and three months and produced a maximum of 26 242 and 196 998 seeds m-2 respectively. Due to high water level and prolonged inundation, the reproductive periods were shorter for the intertidal and reed and sedge species in the TOCE compared to the POE. Seed output during the two reproduction periods varied between the two estuaries. Sarcocornia decumbens and S. tegetaria produced a substantially higher number of seeds in the TOCE compared to the POE, namely 0 - 102 847 versus 20 661 - 48 576 seeds m-²; and 7 001 - 45 542 versus 1 587 – 16 958 seeds m-² respectively. Seed output in the TOCE was significantly higher in S. tegetaria during the second reproduction period despite the significantly lower plant cover, which may be a function of the stressful environment in the TOCE. Seed production of S. meyeriana was significantly higher in the POE compared to the TOCE, with 264 224 - 640 292 compared with 24 050 - 27 643 seeds m-², due to higher plant cover in the POE. The research suggests that macrophyte phenology in the TOCE was significantly influenced by mouth condition. Further, macrophytes were able to demonstrate considerable phenotypic plasticity in response to changing and unfavourable environmental conditions. These data can be used in mouth management plans and freshwater requirement studies in TOCEs to ensure that macrophytes can complete their life-cycles and produce viable seeds for the safeguarding of habitat persistence and ecological processes. In impacted estuaries where artificial mouth opening is practised and the macrophytes have been severely degraded or extirpated, management should ensure that the intertidal and supratidal habitats are not inundated during peak flowering and seed production periods i.e. late spring to early autumn (November to March).
- Full Text:
- Date Issued: 2010
- Authors: Vromans, Deborah Claire
- Date: 2010
- Subjects: Estuarine ecology -- South Africa -- East Kleinemonde Estuary , Aquatic plants -- South Africa -- East Kleinemonde Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10612 , http://hdl.handle.net/10948/1393 , Estuarine ecology -- South Africa -- East Kleinemonde Estuary , Aquatic plants -- South Africa -- East Kleinemonde Estuary
- Description: Temporarily open/closed estuaries (TOCEs) are unpredictable environments that change in response to mouth condition, which is influenced by freshwater flooding or sea storm surges. The aim of the study was to determine whether macrophyte phenology in a TOCE was event driven rather than cyclically predictable and if it differed from permanently open estuaries (POEs). Macrophyte growth and flowering phenology in response to environmental conditions was investigated in the East Kleinemonde Estuary (TOCE) and the Kowie Estuary (POE) along the eastern coastline of South Africa. The lack of freshwater flooding due to low rainfall coupled with several overwash events resulted in a prolonged period of mouth closure from September 2008 to the end of this study period in 2010. This in turn caused the inundation of the supratidal and intertidal habitats, high water level (> 1.57 m amsl) and high salinity (30 - 42 ppt) in the TOCE. Principle Components Analysis showed that high water level and reduced sediments were the most significant environmental factors affecting macrophyte phenology. Macrophyte phenology in the POE was primarily driven by temperature, sediment redox potential and salinity. The saline high water level and reduced sediment significantly reduced macrophyte cover in all habitats in the TOCE. Macrophytes in the POE maintained high cover abundance due to seasonal re-growth compared to the TOCE where cover declined over the sampling period due to the high water level. Subsequent to water level dropping by as little as 11 - 20 cm in the TOCE, the intertidal species Sarcocornia tegetaria and Salicornia meyeriana completed their life-cycles and produced viable seeds within four and three months of germinating respectively. In contrast, the Sarcocornia hybrid and S. meyeriana in the POE took longer to complete their life-cycles, namely seven and nine months respectively, while S. tegataria did not germinate in situ but reproduced vegetatively despite producing seed. In the TOCE, the submerged species Ruppia cirrhosa and Chara vulgaris completed their life-cycles within five and three months and produced a maximum of 26 242 and 196 998 seeds m-2 respectively. Due to high water level and prolonged inundation, the reproductive periods were shorter for the intertidal and reed and sedge species in the TOCE compared to the POE. Seed output during the two reproduction periods varied between the two estuaries. Sarcocornia decumbens and S. tegetaria produced a substantially higher number of seeds in the TOCE compared to the POE, namely 0 - 102 847 versus 20 661 - 48 576 seeds m-²; and 7 001 - 45 542 versus 1 587 – 16 958 seeds m-² respectively. Seed output in the TOCE was significantly higher in S. tegetaria during the second reproduction period despite the significantly lower plant cover, which may be a function of the stressful environment in the TOCE. Seed production of S. meyeriana was significantly higher in the POE compared to the TOCE, with 264 224 - 640 292 compared with 24 050 - 27 643 seeds m-², due to higher plant cover in the POE. The research suggests that macrophyte phenology in the TOCE was significantly influenced by mouth condition. Further, macrophytes were able to demonstrate considerable phenotypic plasticity in response to changing and unfavourable environmental conditions. These data can be used in mouth management plans and freshwater requirement studies in TOCEs to ensure that macrophytes can complete their life-cycles and produce viable seeds for the safeguarding of habitat persistence and ecological processes. In impacted estuaries where artificial mouth opening is practised and the macrophytes have been severely degraded or extirpated, management should ensure that the intertidal and supratidal habitats are not inundated during peak flowering and seed production periods i.e. late spring to early autumn (November to March).
- Full Text:
- Date Issued: 2010
Male aggression and mating opportunity in a poeciliid fish
- Magellan, Kit, Kaiser, Horst
- Authors: Magellan, Kit , Kaiser, Horst
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447556 , vital:74656 , https://doi.org/10.1080/15627020.2010.11657250
- Description: One function of aggression in animals is to gain access to mates. Aggression may therefore be favoured by sexual selection, the strength of which can be assessed using repeatability of aggressive behaviour. Here, we tested the hypotheses that male swordtails, Xiphophorus sp., are consistent in the aggressive and mating behaviours exhibited and in the time spent at a close distance to females (female attendance), and that aggressive males gain increased opportunity to attempt copulation compared to their less aggressive conspecifics (sneak frequency). As predicted, aggression between males, and male display and sneak frequency were repeatable. However, male aggression was not significantly correlated with sneak frequency. The function of aggression in this species is not clear-cut and may have an indirect female access function through formation of dominance hierarchies or defence of resources. A surprising finding highlighted by this study was the contradictory results for consistency in female contact, with high repeatability scores indicating consistency in behaviour but the within-subjects component of repeated measures ANOVA showing differences in female contact between trials. The possible reasons for this discrepancy are discussed.
- Full Text:
- Date Issued: 2010
- Authors: Magellan, Kit , Kaiser, Horst
- Date: 2010
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/447556 , vital:74656 , https://doi.org/10.1080/15627020.2010.11657250
- Description: One function of aggression in animals is to gain access to mates. Aggression may therefore be favoured by sexual selection, the strength of which can be assessed using repeatability of aggressive behaviour. Here, we tested the hypotheses that male swordtails, Xiphophorus sp., are consistent in the aggressive and mating behaviours exhibited and in the time spent at a close distance to females (female attendance), and that aggressive males gain increased opportunity to attempt copulation compared to their less aggressive conspecifics (sneak frequency). As predicted, aggression between males, and male display and sneak frequency were repeatable. However, male aggression was not significantly correlated with sneak frequency. The function of aggression in this species is not clear-cut and may have an indirect female access function through formation of dominance hierarchies or defence of resources. A surprising finding highlighted by this study was the contradictory results for consistency in female contact, with high repeatability scores indicating consistency in behaviour but the within-subjects component of repeated measures ANOVA showing differences in female contact between trials. The possible reasons for this discrepancy are discussed.
- Full Text:
- Date Issued: 2010
Managerial decision making processes and affective outcomes as a function of individual factors and self-efficacy beliefs
- Authors: Myburgh, Wim
- Date: 2010
- Subjects: Decision making
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9893 , http://hdl.handle.net/10948/1141 , Decision making
- Description: Making decisions in the business environment is arguably the most challenging aspect of managers' yet also the easiest to fail in. Unlike individual decisions managers as agents for their organizations make decisions amidst high levels of ambiguity, incomplete information and mostly under time pressure. These are the very conditions that make managers vulnerable to the volition-undermining potential of decision-generated affect precisely when they are feeling over-extended to deal with such demands. Effective managerial decision making (MDM) involves more than applying a set of individual abilities. Managers face numerous obstacles, failures, and setbacks that often carry perturbing self-evaluative implications as well as social consequences that undermine their self-evaluations in ways that impair good use of their decision making skills (Bandura, 1997). Given the absence of a coherent theoretical framework in the literature the conceptual model of relations put forward attempts to organize and simplify how managers make decisions as agents of their organizations. Most conceptualizations apply oversimplified models that focus attention on one or a few variables, neglect the joint constellations of individual variable factors and the influence of individual self-generated influences as a contributing factor in MDM. As an ex post facto explanatory-predictive study the present research offers evidence of these links among the theoretically relevant constructs in order to formulate an account of their relations in a parsimonious framework that could guide future insights to explain and predict the intentions and direction of managerial decision behaviour. Conceptual research has outpaced empirical research in decision making of managers in organizations. A number of mini-theories exists that focus on a few variables using linear, antecedent-consequence relations with manipulations in laboratory environments that deal with decisions in contexts that are very different to those faced by managers. There is limited research on managers as research participants and empirical findings based on non-managerial samples and students may not generalize to managers in real life decision making. The present research used a non-probability, purposive sample (N = 196) of experienced managers in the Western Cape region of South Africa, all employed in private and public organizations (mean age 38.9 years, SD of 7.49, ethnic black managers constituted 15.8 percent of the sample). As part of the study it was necessary to construct and validate custom indicator measures in an independent pilot study from the same population. The pilot study determined the factor structures of the dimensionality and internal consistency of the custom-designed measures by way of both convergent, as well as, discriminative validity. The exploratory factor (EFA) and internal reliability analyses succeeded to provide both a comprehensive and empirical grasp on the constructs as was defined. Further, analyses of both standardized and custom-designed also revealed no significant difference between black and other managers across the pilot samples which provided confidence of the substantive relations of interest (i.e., the associations among the variables). Structural equation modeling (SEM) was chosen as the data analysis strategy of choice and a confirmatory factor analysis (CFA) demonstrated that the operational measures by and large succeeded in providing both a comprehensive and empirical grasp on the constructs as defined. The inter-construct relations were also consistent with expectations. Evidence for convergent validity however proved that the indicator measures for the allocation of attentional resources were less than adequate in order to provide an uncontaminated measure as a latent variable. The structural model was subjected to further scrutiny by way of a spectrum of goodness-of-fit statistics. The analyses revealed that the model was not adequate and the null hypothesis that the model fitted the population data was subsequently, rejected. It was also sensible to assess the degree of lack of fit of the model with reference to RMSEA which revealed a value of .08, that suggested a reasonable model fit. The poor structural model fit could however be attributed to the failure of the measured indicators used to provide an acceptable grasp of the allocation of attentional resources as a latent variable. The inherent structural flaws in the model could however not be unequivocally be ruled out as an additional possibility of poor fit. One conclusion is the possibility of an expanded model that requires additional indicator measures and additional paths. Notwithstanding these limitations, the present research provided support for social cognitive theory that underlies the model. In accordance with the literature and empirical findings the present research demonstrated mangers' decision making is much more than reason-based behaviour. The present research demonstrates the interdependencies and cumulative effects among individual factors, self-efficacy beliefs and temporal volitional processes, as psychological iv mechanisms through which social-structural factors are linked to the quality of MDM processes. The present research also presents an argument for the independent contributions of self-efficacy beliefs as causal influences on "hot temporal processes" that promote accuracy in decision making. Although present research demonstrates that the estimates were greater for cognitive ability than for both self-efficacy beliefs and social self-confidence it does not suggest that personality traits and self-efficacy beliefs have no utility. The present research demonstrates that cognitive ability combines with personality traits, self-efficacy beliefs and temporal processes (decision-generated affect and the allocation of attentional resources) in a complex manner through multiple pathways.
- Full Text:
- Date Issued: 2010
- Authors: Myburgh, Wim
- Date: 2010
- Subjects: Decision making
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9893 , http://hdl.handle.net/10948/1141 , Decision making
- Description: Making decisions in the business environment is arguably the most challenging aspect of managers' yet also the easiest to fail in. Unlike individual decisions managers as agents for their organizations make decisions amidst high levels of ambiguity, incomplete information and mostly under time pressure. These are the very conditions that make managers vulnerable to the volition-undermining potential of decision-generated affect precisely when they are feeling over-extended to deal with such demands. Effective managerial decision making (MDM) involves more than applying a set of individual abilities. Managers face numerous obstacles, failures, and setbacks that often carry perturbing self-evaluative implications as well as social consequences that undermine their self-evaluations in ways that impair good use of their decision making skills (Bandura, 1997). Given the absence of a coherent theoretical framework in the literature the conceptual model of relations put forward attempts to organize and simplify how managers make decisions as agents of their organizations. Most conceptualizations apply oversimplified models that focus attention on one or a few variables, neglect the joint constellations of individual variable factors and the influence of individual self-generated influences as a contributing factor in MDM. As an ex post facto explanatory-predictive study the present research offers evidence of these links among the theoretically relevant constructs in order to formulate an account of their relations in a parsimonious framework that could guide future insights to explain and predict the intentions and direction of managerial decision behaviour. Conceptual research has outpaced empirical research in decision making of managers in organizations. A number of mini-theories exists that focus on a few variables using linear, antecedent-consequence relations with manipulations in laboratory environments that deal with decisions in contexts that are very different to those faced by managers. There is limited research on managers as research participants and empirical findings based on non-managerial samples and students may not generalize to managers in real life decision making. The present research used a non-probability, purposive sample (N = 196) of experienced managers in the Western Cape region of South Africa, all employed in private and public organizations (mean age 38.9 years, SD of 7.49, ethnic black managers constituted 15.8 percent of the sample). As part of the study it was necessary to construct and validate custom indicator measures in an independent pilot study from the same population. The pilot study determined the factor structures of the dimensionality and internal consistency of the custom-designed measures by way of both convergent, as well as, discriminative validity. The exploratory factor (EFA) and internal reliability analyses succeeded to provide both a comprehensive and empirical grasp on the constructs as was defined. Further, analyses of both standardized and custom-designed also revealed no significant difference between black and other managers across the pilot samples which provided confidence of the substantive relations of interest (i.e., the associations among the variables). Structural equation modeling (SEM) was chosen as the data analysis strategy of choice and a confirmatory factor analysis (CFA) demonstrated that the operational measures by and large succeeded in providing both a comprehensive and empirical grasp on the constructs as defined. The inter-construct relations were also consistent with expectations. Evidence for convergent validity however proved that the indicator measures for the allocation of attentional resources were less than adequate in order to provide an uncontaminated measure as a latent variable. The structural model was subjected to further scrutiny by way of a spectrum of goodness-of-fit statistics. The analyses revealed that the model was not adequate and the null hypothesis that the model fitted the population data was subsequently, rejected. It was also sensible to assess the degree of lack of fit of the model with reference to RMSEA which revealed a value of .08, that suggested a reasonable model fit. The poor structural model fit could however be attributed to the failure of the measured indicators used to provide an acceptable grasp of the allocation of attentional resources as a latent variable. The inherent structural flaws in the model could however not be unequivocally be ruled out as an additional possibility of poor fit. One conclusion is the possibility of an expanded model that requires additional indicator measures and additional paths. Notwithstanding these limitations, the present research provided support for social cognitive theory that underlies the model. In accordance with the literature and empirical findings the present research demonstrated mangers' decision making is much more than reason-based behaviour. The present research demonstrates the interdependencies and cumulative effects among individual factors, self-efficacy beliefs and temporal volitional processes, as psychological iv mechanisms through which social-structural factors are linked to the quality of MDM processes. The present research also presents an argument for the independent contributions of self-efficacy beliefs as causal influences on "hot temporal processes" that promote accuracy in decision making. Although present research demonstrates that the estimates were greater for cognitive ability than for both self-efficacy beliefs and social self-confidence it does not suggest that personality traits and self-efficacy beliefs have no utility. The present research demonstrates that cognitive ability combines with personality traits, self-efficacy beliefs and temporal processes (decision-generated affect and the allocation of attentional resources) in a complex manner through multiple pathways.
- Full Text:
- Date Issued: 2010
Managing the implementation of management structure changes at the Eastern Cape Department of Education
- Authors: Muthige, Shumani Ralson
- Date: 2010
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8534 , http://hdl.handle.net/10948/1652
- Description: The Eastern Cape Department of Education has been in the forefront of the media – mostly for the wrong reasons. The major problems that have been reported range from the mismanagement of the feeding schemes, unpaid service providers, lack of adequate infrastructure, corruption committed by the officials, unfilled posts, poor service delivery and the second lowest matriculation pass rate in the country. Although there are many problems, as stated, this study research is focused on the management of change and its implementation in the organisational structure.
- Full Text:
- Date Issued: 2010
- Authors: Muthige, Shumani Ralson
- Date: 2010
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8534 , http://hdl.handle.net/10948/1652
- Description: The Eastern Cape Department of Education has been in the forefront of the media – mostly for the wrong reasons. The major problems that have been reported range from the mismanagement of the feeding schemes, unpaid service providers, lack of adequate infrastructure, corruption committed by the officials, unfilled posts, poor service delivery and the second lowest matriculation pass rate in the country. Although there are many problems, as stated, this study research is focused on the management of change and its implementation in the organisational structure.
- Full Text:
- Date Issued: 2010
Managing the perceptions about affirmitive action (AA)
- Authors: Swartbooi, Aurick Devlin
- Date: 2010
- Subjects: Affirmative action programs -- South Africa , Affirmative action programs -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8684 , http://hdl.handle.net/10948/1120 , Affirmative action programs -- South Africa , Affirmative action programs -- Law and legislation -- South Africa
- Description: The main research problem focused on the effective management of the perceptions about Affirmative Action (AA). A literature study and a survey were conducted to investigate the extent and nature of perceptions, the effect of these perceptions on labour and personal relations, current and suggested management practice of the perceptions of AA. A definition of AA, earlier measures of AA, the implementation of AA in the South African context, the stages of AA, theories, relevant legislation, perceptions and the management thereof are discussed. The survey was conducted at the George and Beaufort West District offices of the Department of Rural Development and Land Reform (DRDLR) with a response rate of 78.95 percent. The perceptions about AA can be managed effectively by complying with legislation, by involving and making all levels of employees responsible for the achievement of employment equity, skills development, personal development, consultation and communication.
- Full Text:
- Date Issued: 2010
- Authors: Swartbooi, Aurick Devlin
- Date: 2010
- Subjects: Affirmative action programs -- South Africa , Affirmative action programs -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8684 , http://hdl.handle.net/10948/1120 , Affirmative action programs -- South Africa , Affirmative action programs -- Law and legislation -- South Africa
- Description: The main research problem focused on the effective management of the perceptions about Affirmative Action (AA). A literature study and a survey were conducted to investigate the extent and nature of perceptions, the effect of these perceptions on labour and personal relations, current and suggested management practice of the perceptions of AA. A definition of AA, earlier measures of AA, the implementation of AA in the South African context, the stages of AA, theories, relevant legislation, perceptions and the management thereof are discussed. The survey was conducted at the George and Beaufort West District offices of the Department of Rural Development and Land Reform (DRDLR) with a response rate of 78.95 percent. The perceptions about AA can be managed effectively by complying with legislation, by involving and making all levels of employees responsible for the achievement of employment equity, skills development, personal development, consultation and communication.
- Full Text:
- Date Issued: 2010
Manure production and nutrient management in pasture-based dairy production systems
- Authors: Svinurai, Walter
- Date: 2010
- Subjects: Manures , Nitrogen -- Metabolism , Aloe -- South Africa , Pine bark , Pastures , Dairy cattle -- Nutrition , Dairy cattle -- Management , Dairy cattle -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11812 , http://hdl.handle.net/10353/475 , Manures , Nitrogen -- Metabolism , Aloe -- South Africa , Pine bark , Pastures , Dairy cattle -- Nutrition , Dairy cattle -- Management , Dairy cattle -- Feeding and feeds
- Description: Manure production and nutrient management in pasture-based dairy production systems by Walter Svinurai The effect of dietary treatments on nutrient excretion was determined and an attempt to improving the retention of excreted nitrogen in stored manure using Aloe ferox leaf gel (AFLG) and pine bark was conducted at a pasture-based dairy farm. The animal mass-balance method was used to determine nutrient excretion by cows fed on three dietary treatments, Lolium perrene-based treatment (LP), Lolium multiforium-based treatment (LM) and Lolium perenne- Trifolium repens -based treatment (LTF). In separate experiments, slurry from dairy cows fed LM was amended with AFLG and pine bark at concentrations of 25, 50, 75 and 100 g/l and stored under anaerobic conditions for 16 days. The highest and lowest excretions of N, P and K were observed in LM and LP treatments, respectively. Increasing dietary N improved K and N retention in milk and, consequently increased milk urea nitrogen (MUN) and N excretion (P < 0.05). The concentrations of AFLG affected N and P retention in manure (P < 0.05). The highest retention in total Kjeldahl nitrogen (TKN) of the initial was 42% AFLG at 25g/l inclusion rate. Ammonium nitrogen (AMN) concentration increased significantly due to the interactive effect of AFLG inclusion rate and time. Pine bark powder significantly improved N and P retention in manure at all concentrations. The retention in TKN was higher (P < 0.05) at 25g/l pine bark powder than other concentrations. The interaction effect of inclusion rate and time increased iii AMN (P < 0.05). Dietary treatments significantly affected nutrient excretion, and AFLG and pine bark considerably improved N retention in stored slurry. Findings from the filed trial suggest the need for more attention on managing dietary nutrients in the post-rainy and cool-dry season when growth of pasture influenced choice of dietary treatments that led to high nutrient excretion. Field simulation of the additives to determine their efficacy and environmental hazards was recommended.
- Full Text:
- Date Issued: 2010
- Authors: Svinurai, Walter
- Date: 2010
- Subjects: Manures , Nitrogen -- Metabolism , Aloe -- South Africa , Pine bark , Pastures , Dairy cattle -- Nutrition , Dairy cattle -- Management , Dairy cattle -- Feeding and feeds
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11812 , http://hdl.handle.net/10353/475 , Manures , Nitrogen -- Metabolism , Aloe -- South Africa , Pine bark , Pastures , Dairy cattle -- Nutrition , Dairy cattle -- Management , Dairy cattle -- Feeding and feeds
- Description: Manure production and nutrient management in pasture-based dairy production systems by Walter Svinurai The effect of dietary treatments on nutrient excretion was determined and an attempt to improving the retention of excreted nitrogen in stored manure using Aloe ferox leaf gel (AFLG) and pine bark was conducted at a pasture-based dairy farm. The animal mass-balance method was used to determine nutrient excretion by cows fed on three dietary treatments, Lolium perrene-based treatment (LP), Lolium multiforium-based treatment (LM) and Lolium perenne- Trifolium repens -based treatment (LTF). In separate experiments, slurry from dairy cows fed LM was amended with AFLG and pine bark at concentrations of 25, 50, 75 and 100 g/l and stored under anaerobic conditions for 16 days. The highest and lowest excretions of N, P and K were observed in LM and LP treatments, respectively. Increasing dietary N improved K and N retention in milk and, consequently increased milk urea nitrogen (MUN) and N excretion (P < 0.05). The concentrations of AFLG affected N and P retention in manure (P < 0.05). The highest retention in total Kjeldahl nitrogen (TKN) of the initial was 42% AFLG at 25g/l inclusion rate. Ammonium nitrogen (AMN) concentration increased significantly due to the interactive effect of AFLG inclusion rate and time. Pine bark powder significantly improved N and P retention in manure at all concentrations. The retention in TKN was higher (P < 0.05) at 25g/l pine bark powder than other concentrations. The interaction effect of inclusion rate and time increased iii AMN (P < 0.05). Dietary treatments significantly affected nutrient excretion, and AFLG and pine bark considerably improved N retention in stored slurry. Findings from the filed trial suggest the need for more attention on managing dietary nutrients in the post-rainy and cool-dry season when growth of pasture influenced choice of dietary treatments that led to high nutrient excretion. Field simulation of the additives to determine their efficacy and environmental hazards was recommended.
- Full Text:
- Date Issued: 2010
Maximization of power in randomized clinical trials using the minimization treatment allocation technique
- Authors: Marange, Chioneso Show
- Date: 2010
- Subjects: Clinical trials -- Statistical methods , Statistical hypothesis testing , Regression analysis , Logistic distribution , Estimation theory
- Language: English
- Type: Thesis , Masters , MSc (Biostatistics and Epidemiology)
- Identifier: vital:11777 , http://hdl.handle.net/10353/399 , Clinical trials -- Statistical methods , Statistical hypothesis testing , Regression analysis , Logistic distribution , Estimation theory
- Description: Generally the primary goal of randomized clinical trials (RCT) is to make comparisons among two or more treatments hence clinical investigators require the most appropriate treatment allocation procedure to yield reliable results regardless of whether the ultimate data suggest a clinically important difference between the treatments being studied. Although recommended by many researchers, the utilization of minimization has been seldom reported in randomized trials mainly because of the controversy surrounding the statistical efficiency in detecting treatment effect and its complexity in implementation. Methods: A SAS simulation code was designed for allocating patients into two different treatment groups. Categorical prognostic factors were used together with multi-level response variables and demonstration of how simulation of data can help to determine the power of the minimization technique was carried out using ordinal logistic regression models. Results: Several scenarios were simulated in this study. Within the selected scenarios, increasing the sample size significantly increased the power of detecting the treatment effect. This was contrary to the case when the probability of allocation was decreased. Power did not change when the probability of allocation given that the treatment groups are balanced was increased. The probability of allocation { } k P was seen to be the only one with a significant effect on treatment balance. Conclusion: Maximum power can be achieved with a sample of size 300 although a small sample of size 200 can be adequate to attain at least 80% power. In order to have maximum power, the probability of allocation should be fixed at 0.75 and set to 0.5 if the treatment groups are equally balanced.
- Full Text:
- Date Issued: 2010
- Authors: Marange, Chioneso Show
- Date: 2010
- Subjects: Clinical trials -- Statistical methods , Statistical hypothesis testing , Regression analysis , Logistic distribution , Estimation theory
- Language: English
- Type: Thesis , Masters , MSc (Biostatistics and Epidemiology)
- Identifier: vital:11777 , http://hdl.handle.net/10353/399 , Clinical trials -- Statistical methods , Statistical hypothesis testing , Regression analysis , Logistic distribution , Estimation theory
- Description: Generally the primary goal of randomized clinical trials (RCT) is to make comparisons among two or more treatments hence clinical investigators require the most appropriate treatment allocation procedure to yield reliable results regardless of whether the ultimate data suggest a clinically important difference between the treatments being studied. Although recommended by many researchers, the utilization of minimization has been seldom reported in randomized trials mainly because of the controversy surrounding the statistical efficiency in detecting treatment effect and its complexity in implementation. Methods: A SAS simulation code was designed for allocating patients into two different treatment groups. Categorical prognostic factors were used together with multi-level response variables and demonstration of how simulation of data can help to determine the power of the minimization technique was carried out using ordinal logistic regression models. Results: Several scenarios were simulated in this study. Within the selected scenarios, increasing the sample size significantly increased the power of detecting the treatment effect. This was contrary to the case when the probability of allocation was decreased. Power did not change when the probability of allocation given that the treatment groups are balanced was increased. The probability of allocation { } k P was seen to be the only one with a significant effect on treatment balance. Conclusion: Maximum power can be achieved with a sample of size 300 although a small sample of size 200 can be adequate to attain at least 80% power. In order to have maximum power, the probability of allocation should be fixed at 0.75 and set to 0.5 if the treatment groups are equally balanced.
- Full Text:
- Date Issued: 2010
Meaning in life and sense of coherence in HIV-positive adults
- Authors: Nolte, Coenraad B
- Date: 2010
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9857 , http://hdl.handle.net/10948/1562
- Description: Human Immunodeficiency Virus (HIV) infection is highly prevalent in South Africa and inevitably leads to an acute stage of the disease referred to as Acquired Immunodeficiency Syndrome (AIDS). Individual variations in the rate of HIV-disease progression are, amongst others, a function of the psychological reactions to an HIV-positive diagnosis and the prevalence of psychosocial stressors. This study was conducted in the context of the salutogenic paradigm and the existential psychological theory of Viktor Frankl. Sense of coherence is a key salutogenic concept and previous studies have suggested a positive correlation between the sense of coherence and the wellbeing of HIV-positive individuals. The objectives of this research were to explore and describe the search for meaning in life, the presence of meaning in life, the sense of coherence and the potential relationships among these concepts in HIV-positive adults. The research sample consisted of 62 participants recruited from an HIV wellness clinic in the Nelson Mandela Metropolitan area. Key findings included the following: Levels of search for meaning in life and presence of meaning in life were not found to be elevated or suppressed in the research sample. No significant relationship was found between the levels of search for meaning in life and presence of meaning in life. The level of sense of coherence of the sample was found to be lower than the level of sense of coherence obtained in previous studies from healthy, mixed populations in South Africa. A statistically significant relationship was found between the levels of presence of meaning in life and the sense of coherence. In conclusion it was proposed that presence of meaning in life is a fortifier of the sense of coherence.
- Full Text:
- Date Issued: 2010
- Authors: Nolte, Coenraad B
- Date: 2010
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9857 , http://hdl.handle.net/10948/1562
- Description: Human Immunodeficiency Virus (HIV) infection is highly prevalent in South Africa and inevitably leads to an acute stage of the disease referred to as Acquired Immunodeficiency Syndrome (AIDS). Individual variations in the rate of HIV-disease progression are, amongst others, a function of the psychological reactions to an HIV-positive diagnosis and the prevalence of psychosocial stressors. This study was conducted in the context of the salutogenic paradigm and the existential psychological theory of Viktor Frankl. Sense of coherence is a key salutogenic concept and previous studies have suggested a positive correlation between the sense of coherence and the wellbeing of HIV-positive individuals. The objectives of this research were to explore and describe the search for meaning in life, the presence of meaning in life, the sense of coherence and the potential relationships among these concepts in HIV-positive adults. The research sample consisted of 62 participants recruited from an HIV wellness clinic in the Nelson Mandela Metropolitan area. Key findings included the following: Levels of search for meaning in life and presence of meaning in life were not found to be elevated or suppressed in the research sample. No significant relationship was found between the levels of search for meaning in life and presence of meaning in life. The level of sense of coherence of the sample was found to be lower than the level of sense of coherence obtained in previous studies from healthy, mixed populations in South Africa. A statistically significant relationship was found between the levels of presence of meaning in life and the sense of coherence. In conclusion it was proposed that presence of meaning in life is a fortifier of the sense of coherence.
- Full Text:
- Date Issued: 2010
Mechanisms of habitat segregation between an invasive (Mytilus galloprovincialis) and an indigenous (Perna perna) mussel: adult growth and mortality
- Bownes, Sarah J, McQuaid, Christopher D
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6868 , http://hdl.handle.net/10962/d1011500
- Description: The invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna coexist intertidally on the south coast of South Africa through partial vertical habitat segregation: M. galloprovincialis dominates the upper shore and P. perna the lower shore. Recruitment patterns can explain the zonation of P. perna, but not the invasive species. We examined the role of post-recruitment interactions by measuring spatial and temporal differences in adult growth and mortality rates of the two species. Specifically, we tested the hypothesis that interspecific differences in growth and mortality reflect adult distribution patterns. The two study locations, Plettenberg Bay and Tsitsikamma, are 70 km apart with two sites (separated by 300–400 m) per location, each divided into three vertical zones. Growth was measured seasonally using different marking methods in 2001 and 2003. Cumulative adult mortality was measured through summer in 2003/2004. Both species generally grew more slowly upshore, but they showed different effects of season. For P. perna, growth was significantly reduced in winter in the low zone, but unaffected by season in the high zone. For M. galloprovincialis, growth was either unaffected by season or increased in winter, even in the high zone. Thus, growth of P. perna and M. galloprovincialis was reduced under cool winter and warm summer temperatures, respectively; and while growth was more similar between species in summer, M. galloprovincialis grew much faster than P. perna in winter. Mortality of P. perna increased upshore. For M. galloprovincialis, mortality was not zone-dependent and was significantly greater than for P. perna on the low-shore and (generally) across the shore in Tsitsikamma. Both species had higher growth and mortality rates in Plettenberg Bay than in Tsitsikamma. Thus, P. perna seems able to maintain spatial dominance on the low-shore and at certain sites because of higher mortality of M. galloprovincialis. We conclude that seasonality in growth of the two species reflects their biogeographic affinities and that coexistence is possible through pre-recruitment effects that limit the vertical distribution of P. perna and post-recruitment effects that limit M. galloprovincialis.
- Full Text:
- Date Issued: 2010
- Authors: Bownes, Sarah J , McQuaid, Christopher D
- Date: 2010
- Language: English
- Type: Article
- Identifier: vital:6868 , http://hdl.handle.net/10962/d1011500
- Description: The invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna coexist intertidally on the south coast of South Africa through partial vertical habitat segregation: M. galloprovincialis dominates the upper shore and P. perna the lower shore. Recruitment patterns can explain the zonation of P. perna, but not the invasive species. We examined the role of post-recruitment interactions by measuring spatial and temporal differences in adult growth and mortality rates of the two species. Specifically, we tested the hypothesis that interspecific differences in growth and mortality reflect adult distribution patterns. The two study locations, Plettenberg Bay and Tsitsikamma, are 70 km apart with two sites (separated by 300–400 m) per location, each divided into three vertical zones. Growth was measured seasonally using different marking methods in 2001 and 2003. Cumulative adult mortality was measured through summer in 2003/2004. Both species generally grew more slowly upshore, but they showed different effects of season. For P. perna, growth was significantly reduced in winter in the low zone, but unaffected by season in the high zone. For M. galloprovincialis, growth was either unaffected by season or increased in winter, even in the high zone. Thus, growth of P. perna and M. galloprovincialis was reduced under cool winter and warm summer temperatures, respectively; and while growth was more similar between species in summer, M. galloprovincialis grew much faster than P. perna in winter. Mortality of P. perna increased upshore. For M. galloprovincialis, mortality was not zone-dependent and was significantly greater than for P. perna on the low-shore and (generally) across the shore in Tsitsikamma. Both species had higher growth and mortality rates in Plettenberg Bay than in Tsitsikamma. Thus, P. perna seems able to maintain spatial dominance on the low-shore and at certain sites because of higher mortality of M. galloprovincialis. We conclude that seasonality in growth of the two species reflects their biogeographic affinities and that coexistence is possible through pre-recruitment effects that limit the vertical distribution of P. perna and post-recruitment effects that limit M. galloprovincialis.
- Full Text:
- Date Issued: 2010
Media convergence : an analysis of consumer engagement
- Authors: Muwanga-Zake, Semeyi
- Date: 2010
- Subjects: Mass media , Journalism
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8612 , http://hdl.handle.net/10948/1557 , Mass media , Journalism
- Description: Media convergence has meant that the traditional separations between the various media industries, such as the internet, broadcasting and telephone networks are slowly collapsing due to the growing use and influence of digital electronics - in effect, morphing or transforming the media landscape. A fundamental change in today's media landscape has been the shift in control over media content, consumer consumption patterns as well as the manner and level at which consumers interact. Thus, the extent to which success is achieved now depends on a customer centric engagement strategy that can be implemented across converged platforms. This study considers the challenges posed by media convergence. It also investigates how organisations adjusted strategies to mitigate these challenges.
- Full Text:
- Date Issued: 2010
- Authors: Muwanga-Zake, Semeyi
- Date: 2010
- Subjects: Mass media , Journalism
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8612 , http://hdl.handle.net/10948/1557 , Mass media , Journalism
- Description: Media convergence has meant that the traditional separations between the various media industries, such as the internet, broadcasting and telephone networks are slowly collapsing due to the growing use and influence of digital electronics - in effect, morphing or transforming the media landscape. A fundamental change in today's media landscape has been the shift in control over media content, consumer consumption patterns as well as the manner and level at which consumers interact. Thus, the extent to which success is achieved now depends on a customer centric engagement strategy that can be implemented across converged platforms. This study considers the challenges posed by media convergence. It also investigates how organisations adjusted strategies to mitigate these challenges.
- Full Text:
- Date Issued: 2010
Mediating factors in the relationship between childhood sexual abuse and HIV Sexual risk behaviour among men who have sex with men
- Authors: Heusser, Shelly Lucien
- Date: 2010
- Subjects: Adult child sexual abuse victims -- Sexual behavior -- South Africa , Sexually transmitted diseases -- Psychological aspects , Risk-taking (Psychology)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9873 , http://hdl.handle.net/10948/1398 , Adult child sexual abuse victims -- Sexual behavior -- South Africa , Sexually transmitted diseases -- Psychological aspects , Risk-taking (Psychology)
- Description: Previous studies have indicated an association between childhood sexual abuse (CSA) and an increased risk of engaging in unsafe behaviours during adulthood, including risky sexual practices. This study examined the relationship between CSA and adult HIV sexual risk behaviour among a sample of South African men who have sex with men (MSM). Potential pathological long-term mental health outcomes of CSA, including dissociation, sex-related substance abuse, depression, sexual compulsivity, impaired interpersonal communication, and over-reliance on submissive sexual scripts, were treated as variables mediating the relationship between CSA and sexual risk behaviour. Men frequenting a gay internet dating site were randomly selected to complete an electronic version of the anonymous survey. Results indicate that one-fourth of participants reported a history of CSA. Men with a history of unwanted sexual activity during childhood were more likely to report recreational substance abuse, sex-related substance abuse, sexual compulsivity, and adult revictimisation experiences. Men who were abused were also more likely to engage in unprotected anal intercourse compared to those who were not abused. Mediation analyses revealed that MSM who are survivors of CSA are particularly susceptible to drug abuse, sex-related drug abuse, and sexual compulsivity, and these sequelae in turn predict higher reported numbers of male sexual partners. The current data suggest that CSA is widespread among men at high risk for HIV infection, and that it may have a devastating influence on the quality of life and health risk behaviour of these men. These results also highlight the importance of mental health services and new approaches in HIV prevention for MSM who have been sexually abused as children. Further research is needed into the contextual factors of the childhood abuse experience which account for the variability in longterm negative mental health outcomes of CSA survivors.
- Full Text:
- Date Issued: 2010
- Authors: Heusser, Shelly Lucien
- Date: 2010
- Subjects: Adult child sexual abuse victims -- Sexual behavior -- South Africa , Sexually transmitted diseases -- Psychological aspects , Risk-taking (Psychology)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9873 , http://hdl.handle.net/10948/1398 , Adult child sexual abuse victims -- Sexual behavior -- South Africa , Sexually transmitted diseases -- Psychological aspects , Risk-taking (Psychology)
- Description: Previous studies have indicated an association between childhood sexual abuse (CSA) and an increased risk of engaging in unsafe behaviours during adulthood, including risky sexual practices. This study examined the relationship between CSA and adult HIV sexual risk behaviour among a sample of South African men who have sex with men (MSM). Potential pathological long-term mental health outcomes of CSA, including dissociation, sex-related substance abuse, depression, sexual compulsivity, impaired interpersonal communication, and over-reliance on submissive sexual scripts, were treated as variables mediating the relationship between CSA and sexual risk behaviour. Men frequenting a gay internet dating site were randomly selected to complete an electronic version of the anonymous survey. Results indicate that one-fourth of participants reported a history of CSA. Men with a history of unwanted sexual activity during childhood were more likely to report recreational substance abuse, sex-related substance abuse, sexual compulsivity, and adult revictimisation experiences. Men who were abused were also more likely to engage in unprotected anal intercourse compared to those who were not abused. Mediation analyses revealed that MSM who are survivors of CSA are particularly susceptible to drug abuse, sex-related drug abuse, and sexual compulsivity, and these sequelae in turn predict higher reported numbers of male sexual partners. The current data suggest that CSA is widespread among men at high risk for HIV infection, and that it may have a devastating influence on the quality of life and health risk behaviour of these men. These results also highlight the importance of mental health services and new approaches in HIV prevention for MSM who have been sexually abused as children. Further research is needed into the contextual factors of the childhood abuse experience which account for the variability in longterm negative mental health outcomes of CSA survivors.
- Full Text:
- Date Issued: 2010
Mental health care practitioners' perceptions of mental illness within the isiXhosa cultural context
- Authors: Lombo, Nocawa Philomina
- Date: 2010
- Subjects: Mental illness -- South Africa , Mental health personnel , Psychiatric nursing , Xhosa (African people) -- Psychology , Xhosa (African people) -- Social life and customs
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9997 , http://hdl.handle.net/10948/1179 , Mental illness -- South Africa , Mental health personnel , Psychiatric nursing , Xhosa (African people) -- Psychology , Xhosa (African people) -- Social life and customs
- Description: This study sought to explore the perceptions of mental health care practitioners’ perceptions on mental illness within the isiXhosa cultural context. A qualitative exploratory descriptive and contextual design was used for the study. A non-probability purposive sampling method was used to select eight participants from Komani Hospital in Queenstown. Data was collected through semi-structured interviews. The services of an Independent Interviewer were used to avoid any bias as interviews took place where the researcher is employed. All interviews were transcribed verbatim and the data collected was analyzed according to Tesch’s eight steps of data analysis as described in Cresswell (1994:155). The researcher utilized services of an Independent Coder who verified the identified major themes. Four major themes emerged from the analysis of the interview: Mental health care practitioner’s perceptions of mental illness, perception of the causes of mental illness within the isiXhosa cultural context, mental health care practitioners’ views in the management and treatment of mental illness and suggestions put forward to improve the services to mental health care users. The major findings of this study were the lack of knowledge of culture of mental health care users. It is recommended that it would be proper if there could be co-operation between mental health care practitioners and traditional healers by working together as a team.
- Full Text:
- Date Issued: 2010
Mental health care practitioners' perceptions of mental illness within the isiXhosa cultural context
- Authors: Lombo, Nocawa Philomina
- Date: 2010
- Subjects: Mental illness -- South Africa , Mental health personnel , Psychiatric nursing , Xhosa (African people) -- Psychology , Xhosa (African people) -- Social life and customs
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9997 , http://hdl.handle.net/10948/1179 , Mental illness -- South Africa , Mental health personnel , Psychiatric nursing , Xhosa (African people) -- Psychology , Xhosa (African people) -- Social life and customs
- Description: This study sought to explore the perceptions of mental health care practitioners’ perceptions on mental illness within the isiXhosa cultural context. A qualitative exploratory descriptive and contextual design was used for the study. A non-probability purposive sampling method was used to select eight participants from Komani Hospital in Queenstown. Data was collected through semi-structured interviews. The services of an Independent Interviewer were used to avoid any bias as interviews took place where the researcher is employed. All interviews were transcribed verbatim and the data collected was analyzed according to Tesch’s eight steps of data analysis as described in Cresswell (1994:155). The researcher utilized services of an Independent Coder who verified the identified major themes. Four major themes emerged from the analysis of the interview: Mental health care practitioner’s perceptions of mental illness, perception of the causes of mental illness within the isiXhosa cultural context, mental health care practitioners’ views in the management and treatment of mental illness and suggestions put forward to improve the services to mental health care users. The major findings of this study were the lack of knowledge of culture of mental health care users. It is recommended that it would be proper if there could be co-operation between mental health care practitioners and traditional healers by working together as a team.
- Full Text:
- Date Issued: 2010
Messages from the deep : water divinities, dreams and diviners in Southern Africa
- Authors: Bernard, Penelope Susan
- Date: 2010
- Subjects: Dreams -- Religious aspects , Zulu (African people) -- Religion , Xhosa (African people) -- Religion , Shamanism -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2112 , http://hdl.handle.net/10962/d1007644 , Dreams -- Religious aspects , Zulu (African people) -- Religion , Xhosa (African people) -- Religion , Shamanism -- South Africa
- Description: This thesis is a comparative regional study of a complex of beliefs and practices regarding the water divinities in southern Africa. These snake and mermaid-like divinities, which are said to work in conjunction with one's ancestors, are believed to be responsible for the calling and training of certain diviner-healers by taking them underwater for periods of time. In addition to granting healing knowledge, these divinities are associated with fertility, water and rain, and the origins of humanity. The research combines comparative ethnography with the anthropology of extraordinary experience (AEE), and focuses particularly on the Zulu, Cape Nguni, Shona and Khoisan groups. The use of the 'radical participation' method, as recommended by AEE, was facilitated by the author being identified as having a ' calling' from these water divinities, which subsequently resulted in her initiation under the guidance of a Zulu isangoma (diviner-healer) who had reputedly been taken underwater. The research details the rituals that were performed and how dreams are used to guide the training process of izangoma. This resulted in the research process being largely dream-directed, in that the author traces how the izangoma responded to various dreams she had and how these responses opened new avenues for understanding the phenomenon of the water divinities. The comparative study thus combines literature sources, field research and dream-directed experiences, and reveals a complex of recurring themes, symbols and norms pertaining to the water divinities across the selected groups. In seeking to explain both the commonalities and differences between these groups, the author argues for a four-level explanatory model that combines both conventional anthropological theory and extraordinary experience. Responses to the author's dream-led experiences are used to throw light on the conflicting discourses of morality regarding traditional healers and the water divinities in the context of political-economic transformations relating to capitalism and the moral economy; to illuminate the blending of ideas and practices between Zulu Zionists and diviner-healer traditions; and to link up with certain issues relating to San rock art, rain-making and healing rituals, which contribute to the debates regarding trance-induced rock art in southern Africa.
- Full Text:
- Date Issued: 2010
- Authors: Bernard, Penelope Susan
- Date: 2010
- Subjects: Dreams -- Religious aspects , Zulu (African people) -- Religion , Xhosa (African people) -- Religion , Shamanism -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2112 , http://hdl.handle.net/10962/d1007644 , Dreams -- Religious aspects , Zulu (African people) -- Religion , Xhosa (African people) -- Religion , Shamanism -- South Africa
- Description: This thesis is a comparative regional study of a complex of beliefs and practices regarding the water divinities in southern Africa. These snake and mermaid-like divinities, which are said to work in conjunction with one's ancestors, are believed to be responsible for the calling and training of certain diviner-healers by taking them underwater for periods of time. In addition to granting healing knowledge, these divinities are associated with fertility, water and rain, and the origins of humanity. The research combines comparative ethnography with the anthropology of extraordinary experience (AEE), and focuses particularly on the Zulu, Cape Nguni, Shona and Khoisan groups. The use of the 'radical participation' method, as recommended by AEE, was facilitated by the author being identified as having a ' calling' from these water divinities, which subsequently resulted in her initiation under the guidance of a Zulu isangoma (diviner-healer) who had reputedly been taken underwater. The research details the rituals that were performed and how dreams are used to guide the training process of izangoma. This resulted in the research process being largely dream-directed, in that the author traces how the izangoma responded to various dreams she had and how these responses opened new avenues for understanding the phenomenon of the water divinities. The comparative study thus combines literature sources, field research and dream-directed experiences, and reveals a complex of recurring themes, symbols and norms pertaining to the water divinities across the selected groups. In seeking to explain both the commonalities and differences between these groups, the author argues for a four-level explanatory model that combines both conventional anthropological theory and extraordinary experience. Responses to the author's dream-led experiences are used to throw light on the conflicting discourses of morality regarding traditional healers and the water divinities in the context of political-economic transformations relating to capitalism and the moral economy; to illuminate the blending of ideas and practices between Zulu Zionists and diviner-healer traditions; and to link up with certain issues relating to San rock art, rain-making and healing rituals, which contribute to the debates regarding trance-induced rock art in southern Africa.
- Full Text:
- Date Issued: 2010
Metabolic energy relations in the Eastern Cape Angulate Tortoise (Chersina Anguluta)
- Authors: Setlalekgomo, Mpho Rinah
- Date: 2010
- Subjects: Eastern Cape angulate Tortoise , Oxygen consumption (Physiology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10690 , http://hdl.handle.net/10948/1400 , Eastern Cape angulate Tortoise , Oxygen consumption (Physiology)
- Description: The daily oxygen consumption (VO2) pattern, the effects of varying ambient temperatures, season and mass on the resting oxygen consumption (RVO2) of Chersina angulata of the Eastern Cape were investigated. The RVO2 was measured using flow-through respirometry and specific resting oxygen consumption (sRVO2) calculated. To determine the daily pattern in the VO2 of C. angulata, the tortoises were acclimated in an environmentally controlled room (ECR) to an ambient temperature of 26 ± 1°C and a light regime of 14 hours of light and 10 hours of darkness (14L:10D) for at least a week prior to the RVO2 measurements. The RVO2 was measured at a constant temperature of 26 ± 1°C, and at three different light regimes, namely: 14L:10D, constant darkness (DD) and constant light (LL). There were no significant effects of mass or gender on the sRVO2 of the tortoises used. Rhythms in the sRVO2 were detected under all three light regimes. The amplitudes of the rhythm were largest at 14L:10D, followed by DD and smallest at LL regime. The persistence of the rhythmic pattern under constant conditions suggests the existence of an endogenous circadian rhythm in the sRVO2 for adult C. angulata. To test for the effect of ambient temperature on the sRVO2 of adult C. angulata, the tortoises were acclimated to 22 ± 1°C and a 14L:10D light regime prior to the RVO2 measurements. RVO2 was measured at eight experimental temperatures; 14°C, 18°C, 22°C, 26°C, 30°C, 35°C, 38°C and 40°C. The sRVO2 was not influenced by gender and increased with experimental temperatures, but this did not happen consistently over the whole range of temperatures tested. A plateau, possibly a thermal preferendum zone, was detected within the temperature range of 26 - 38°C. Determination of seasonal effect on the sRVO2 of adult C. angulata was accomplished by acclimating tortoises to standard summer and winter conditions. Seasonal effects were tested in the appropriate seasons. Winter experiments were conducted in winter and summer experiments conducted in summer. The RVO2 was measured at experimental temperature 14°C, 18°C and 22°C. In addition RVO2 of iv winter-acclimated tortoises was also measured at 10°C. The sRVO2 increased significantly with increasing temperature within the temperature range tested. No distinct pattern was observed in the seasonal acclimation of adult C. angulata. The metabolic rate-temperature curves of the summer and the winter-acclimated tortoises cross each other. Season and temperature had no significant effects on the mass-scaling exponent of the sRVO2. The exponent ranged from 0.48 to 0.73 within the temperature range of 22 - 38°C. Below and above this temperature range, the exponent ranged from 1.47 to 1.67. An inverse relationship was observed between sRVO2 and body mass over the temperature range of 22 - 38°C. At 14°C and 18°C, sRVO2 increased with body mass, while at 10°C and at 40°C the slope was 1.01.
- Full Text:
- Date Issued: 2010
- Authors: Setlalekgomo, Mpho Rinah
- Date: 2010
- Subjects: Eastern Cape angulate Tortoise , Oxygen consumption (Physiology)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10690 , http://hdl.handle.net/10948/1400 , Eastern Cape angulate Tortoise , Oxygen consumption (Physiology)
- Description: The daily oxygen consumption (VO2) pattern, the effects of varying ambient temperatures, season and mass on the resting oxygen consumption (RVO2) of Chersina angulata of the Eastern Cape were investigated. The RVO2 was measured using flow-through respirometry and specific resting oxygen consumption (sRVO2) calculated. To determine the daily pattern in the VO2 of C. angulata, the tortoises were acclimated in an environmentally controlled room (ECR) to an ambient temperature of 26 ± 1°C and a light regime of 14 hours of light and 10 hours of darkness (14L:10D) for at least a week prior to the RVO2 measurements. The RVO2 was measured at a constant temperature of 26 ± 1°C, and at three different light regimes, namely: 14L:10D, constant darkness (DD) and constant light (LL). There were no significant effects of mass or gender on the sRVO2 of the tortoises used. Rhythms in the sRVO2 were detected under all three light regimes. The amplitudes of the rhythm were largest at 14L:10D, followed by DD and smallest at LL regime. The persistence of the rhythmic pattern under constant conditions suggests the existence of an endogenous circadian rhythm in the sRVO2 for adult C. angulata. To test for the effect of ambient temperature on the sRVO2 of adult C. angulata, the tortoises were acclimated to 22 ± 1°C and a 14L:10D light regime prior to the RVO2 measurements. RVO2 was measured at eight experimental temperatures; 14°C, 18°C, 22°C, 26°C, 30°C, 35°C, 38°C and 40°C. The sRVO2 was not influenced by gender and increased with experimental temperatures, but this did not happen consistently over the whole range of temperatures tested. A plateau, possibly a thermal preferendum zone, was detected within the temperature range of 26 - 38°C. Determination of seasonal effect on the sRVO2 of adult C. angulata was accomplished by acclimating tortoises to standard summer and winter conditions. Seasonal effects were tested in the appropriate seasons. Winter experiments were conducted in winter and summer experiments conducted in summer. The RVO2 was measured at experimental temperature 14°C, 18°C and 22°C. In addition RVO2 of iv winter-acclimated tortoises was also measured at 10°C. The sRVO2 increased significantly with increasing temperature within the temperature range tested. No distinct pattern was observed in the seasonal acclimation of adult C. angulata. The metabolic rate-temperature curves of the summer and the winter-acclimated tortoises cross each other. Season and temperature had no significant effects on the mass-scaling exponent of the sRVO2. The exponent ranged from 0.48 to 0.73 within the temperature range of 22 - 38°C. Below and above this temperature range, the exponent ranged from 1.47 to 1.67. An inverse relationship was observed between sRVO2 and body mass over the temperature range of 22 - 38°C. At 14°C and 18°C, sRVO2 increased with body mass, while at 10°C and at 40°C the slope was 1.01.
- Full Text:
- Date Issued: 2010
Metallophthalocyanine-based molecular materials as catalysts for electrochemical reactions
- Zagal, José H, Griveau, Sophie J, Silva, Francisco, Nyokong, Tebello, Bedioui, Fethi
- Authors: Zagal, José H , Griveau, Sophie J , Silva, Francisco , Nyokong, Tebello , Bedioui, Fethi
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7239 , http://hdl.handle.net/10962/d1019718
- Description: Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O2 only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O2, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors. , Original publication is available at http://dx.doi.org/10.1016/j.ccr.2010.05.001
- Full Text: false
- Date Issued: 2010
- Authors: Zagal, José H , Griveau, Sophie J , Silva, Francisco , Nyokong, Tebello , Bedioui, Fethi
- Date: 2010
- Language: English
- Type: text , Article
- Identifier: vital:7239 , http://hdl.handle.net/10962/d1019718
- Description: Metallophthalocyanines confined on the surface of electrodes are active catalysts for a large variety of electrochemical reactions and electrode surfaces modified by these complexes can be obtained by simple adsorption on graphite and carbon. However, more stable electrodes can be achieved by coating their surfaces with electropolymerized layers of the complexes, that show similar activity than their monomer counterparts. In all cases, fundamental studies carried out with adsorbed layers of these complexes have shown that the redox potential is a very good reactivity index for predicting the catalytic activity of the complexes. Volcano-shaped correlations have been found between the electrocatalytic activity (as log I at constant E) versus the Co(II)/(I) formal potential (E°′) of Co-macrocyclics for the oxidation of several thiols, hydrazine and glucose. For the electroreduction of O2 only linear correlations between the electrocatalytic activity versus the M(III)/M(II) formal potential have been found using Cr, Mn, Fe and Co phthalocyanines but it is likely that these correlations are “incomplete volcano” correlations. The volcano correlations strongly suggest that E°′, the formal potential of the complex needs to be in a rather narrow potential window for achieving maximum activity, probably corresponding to surface coverages of an M-molecule adduct equal to 0.5 and to standard free energies of adsorption of the reacting molecule on the complex active site equal to zero. These results indicate that the catalytic activity of metallophthalocyanines for the oxidation of several molecules can be “tuned” by manipulating the E°′ formal potential, using proper groups on the macrocyclic ligand. This review emphasizes once more that metallophthalocyanines are extremely versatile materials with many applications in electrocatalysis, electroanalysis, just to mention a few, and they provide very good models for testing their catalytic activity for several reactions. Even though the earlier applications of these complexes were focused on providing active materials for electroreduction of O2, for making active cathodes for fuel cells, the main trend in the literature nowadays is to use these complexes for making active electrodes for electrochemical sensors. , Original publication is available at http://dx.doi.org/10.1016/j.ccr.2010.05.001
- Full Text: false
- Date Issued: 2010
Metallophthalocyanines as electrocatalysts and superoxide dismutase mimics
- Authors: Matemadombo, Fungisai
- Date: 2010
- Subjects: Mimicry (Chemistry) Electrocatalysis Superoxide dismutase Electrochemistry Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4325 , http://hdl.handle.net/10962/d1004985
- Description: Syntheses, spectral, electrochemical, and spectroelectrochemical studies of iron, cobalt, and manganese phthalocyanines are reported. The novel coordination of cobalt tetracarboxy metallophthalocyanine to an electrode premodified with aryl radicals and its use in the detection of thiocyanate are reported. This work describes the catalytic activity of cobalt phthalocyanine (CoPc) derivatives adsorbed onto glassy carbon electrodes for the electrocatalytical detection of nitrite, Lcysteine, and melatonin. The modified electrodes efficiently detected nitrite. The CoPc derivative modified electrodes proficiently detected L-cysteine whereas an un-modified electrode could not. This work presents the innovative electrochemical detection of melatonin using electrodes adsorbed with CoPc derivatives. These electrodes detected melatonin at more favorable electrochemical parameters relative to an un-modified gold electrode. The limits of melatonin detection of the modified electrodes lay in the 10⁻⁷ to 10⁻⁶ M region. The modified electrodes accurately detected capsule melatonin concentrations as specified by the supplier and could differentiate between a mixture of melatonin, tryptophan, and ascorbic acid. They reliably detected nitrite, L-cysteine, and melatonin in the 10⁻⁴ to 10⁻² M region. Metallophthalocyanine complexes substituted with thio groups were employed as self assembled monolayers (SAMs). Voltammetry, impedance, atomic force microscopy, and scanning electrochemical microscopy proved that the SAMs all act as selective and efficient barriers to ion permeability. All the SAMs in this work can be used as effective electrochemical sensors of nitrite and L-cysteine in the 10⁻⁴ to 10⁻² M region with competitive limits of detection whereas an un-modified electrode cannot detect Lcysteine. The manganese phthalocyanine SAM modified electrodes are arguably better nitrite and L-cysteine electrocatalysts relative to their iron and cobalt counterparts. Manganese phthalocyanines were used as superoxide dismutase (SOD) mimics. All manganese phthalocyanine complexes in this work acted as SOD mimics in an enzymatic system of superoxide production. From cellular studies, complexes 6d, 6e, 8d, 8e act as intracellular SOD mimics and are without significantly high cellular toxicity.
- Full Text:
- Date Issued: 2010
- Authors: Matemadombo, Fungisai
- Date: 2010
- Subjects: Mimicry (Chemistry) Electrocatalysis Superoxide dismutase Electrochemistry Phthalocyanines
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4325 , http://hdl.handle.net/10962/d1004985
- Description: Syntheses, spectral, electrochemical, and spectroelectrochemical studies of iron, cobalt, and manganese phthalocyanines are reported. The novel coordination of cobalt tetracarboxy metallophthalocyanine to an electrode premodified with aryl radicals and its use in the detection of thiocyanate are reported. This work describes the catalytic activity of cobalt phthalocyanine (CoPc) derivatives adsorbed onto glassy carbon electrodes for the electrocatalytical detection of nitrite, Lcysteine, and melatonin. The modified electrodes efficiently detected nitrite. The CoPc derivative modified electrodes proficiently detected L-cysteine whereas an un-modified electrode could not. This work presents the innovative electrochemical detection of melatonin using electrodes adsorbed with CoPc derivatives. These electrodes detected melatonin at more favorable electrochemical parameters relative to an un-modified gold electrode. The limits of melatonin detection of the modified electrodes lay in the 10⁻⁷ to 10⁻⁶ M region. The modified electrodes accurately detected capsule melatonin concentrations as specified by the supplier and could differentiate between a mixture of melatonin, tryptophan, and ascorbic acid. They reliably detected nitrite, L-cysteine, and melatonin in the 10⁻⁴ to 10⁻² M region. Metallophthalocyanine complexes substituted with thio groups were employed as self assembled monolayers (SAMs). Voltammetry, impedance, atomic force microscopy, and scanning electrochemical microscopy proved that the SAMs all act as selective and efficient barriers to ion permeability. All the SAMs in this work can be used as effective electrochemical sensors of nitrite and L-cysteine in the 10⁻⁴ to 10⁻² M region with competitive limits of detection whereas an un-modified electrode cannot detect Lcysteine. The manganese phthalocyanine SAM modified electrodes are arguably better nitrite and L-cysteine electrocatalysts relative to their iron and cobalt counterparts. Manganese phthalocyanines were used as superoxide dismutase (SOD) mimics. All manganese phthalocyanine complexes in this work acted as SOD mimics in an enzymatic system of superoxide production. From cellular studies, complexes 6d, 6e, 8d, 8e act as intracellular SOD mimics and are without significantly high cellular toxicity.
- Full Text:
- Date Issued: 2010