Phylogenetics and historical biogeography of the Teloganodidae (Ephemeroptera)
- Pereira da Conceicoa, Lyndall Louise
- Authors: Pereira da Conceicoa, Lyndall Louise
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64900 , vital:28629
- Description: The Teloganodidae are a mayfly family endemic to the southwestern Cape (South Africa), with relatives in Madagascar and Asia. Like many other aquatic invertebrates in Africa, they have been considerably understudied. Research into biodiversity and biogeography allows an understanding of the earth’s biota, producing knowledge which can be used to develop strategies to preserve and monitor this biota. Mismanagement of water systems places biodiversity of river fauna under an ever-increasing extinction threat. This investigation explores rivers in under-collected areas to determine how well teloganodids have been represented in the literature, with four genera and five species described at the onset of this study. A lectotype for Lestagella penicillata Barnard (1940) has been elected and described in detail, setting “benchmark” characters for future descriptions. Standard DNA sequencing methods provide portions of three mitochondrial genes; cytochrome oxidase subunit I (COI), small subunit ribosomal 16S RNA (16S), 12S ribosomal DNA (12S) and two nuclear genes, Histone 3 (H3) and 28S ribosomal DNA (28S) for up to 255 specimens. Fore and hind wings of 79 teloganodid adults were used to examine phylogenetic signal and evolutionary divergence using geometric morphometrics. A multi-faceted approach is used to investigate relationships between clades and the effects of deep-time climatic and landform changes which have influenced the diversity and distribution seen today. Tree (Bayesian Inference and Maximum Likelihood) and network (parsimony) phylogenies, ancestral reconstruction, historical biogeography and wingevolution of the Teloganodidae are investigated. Species tree analyses discovered 27 species and six genera. Distinct lineages are restricted to catchments, and strong phylogeographic structure was found within most genera. Southern African Teloganodidae are shown to have originated in the Cretaceous, with divergence and dispersal of lineages depended on their established locality at the time of tectonic events (uplift) and climatic changes (sea level regressions and transgressions). Geographic clines in wing-shape of Lestagella across its range imply evolutionary adaptations to specific catchment landscape and environment. A detailed analysis of biodiversity has many valuable contributions, from directing future research, understanding adaptive processes, fine-tuning phylogeographical and evolutionary hypotheses, to improving management and conservation decisions in order to preserve endemic biodiversity hotspots.
- Full Text:
- Date Issued: 2016
- Authors: Pereira da Conceicoa, Lyndall Louise
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64900 , vital:28629
- Description: The Teloganodidae are a mayfly family endemic to the southwestern Cape (South Africa), with relatives in Madagascar and Asia. Like many other aquatic invertebrates in Africa, they have been considerably understudied. Research into biodiversity and biogeography allows an understanding of the earth’s biota, producing knowledge which can be used to develop strategies to preserve and monitor this biota. Mismanagement of water systems places biodiversity of river fauna under an ever-increasing extinction threat. This investigation explores rivers in under-collected areas to determine how well teloganodids have been represented in the literature, with four genera and five species described at the onset of this study. A lectotype for Lestagella penicillata Barnard (1940) has been elected and described in detail, setting “benchmark” characters for future descriptions. Standard DNA sequencing methods provide portions of three mitochondrial genes; cytochrome oxidase subunit I (COI), small subunit ribosomal 16S RNA (16S), 12S ribosomal DNA (12S) and two nuclear genes, Histone 3 (H3) and 28S ribosomal DNA (28S) for up to 255 specimens. Fore and hind wings of 79 teloganodid adults were used to examine phylogenetic signal and evolutionary divergence using geometric morphometrics. A multi-faceted approach is used to investigate relationships between clades and the effects of deep-time climatic and landform changes which have influenced the diversity and distribution seen today. Tree (Bayesian Inference and Maximum Likelihood) and network (parsimony) phylogenies, ancestral reconstruction, historical biogeography and wingevolution of the Teloganodidae are investigated. Species tree analyses discovered 27 species and six genera. Distinct lineages are restricted to catchments, and strong phylogeographic structure was found within most genera. Southern African Teloganodidae are shown to have originated in the Cretaceous, with divergence and dispersal of lineages depended on their established locality at the time of tectonic events (uplift) and climatic changes (sea level regressions and transgressions). Geographic clines in wing-shape of Lestagella across its range imply evolutionary adaptations to specific catchment landscape and environment. A detailed analysis of biodiversity has many valuable contributions, from directing future research, understanding adaptive processes, fine-tuning phylogeographical and evolutionary hypotheses, to improving management and conservation decisions in order to preserve endemic biodiversity hotspots.
- Full Text:
- Date Issued: 2016
Phylogenetics of the keratin-feeding beetle family Trogidae (Coleoptera: Scarabaeoidea)
- Authors: Strümpher, Werner Petrus
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/1232 , vital:20037
- Description: Trogidae constitute a monophyletic and biologically unique family within the Scarabaeoidea, being the only keratinophagous group in its superfamily. Traditionally, the family has been divided into three distinctive genera, Omorgus Erichson, Polynoncus Burmeister, and Trox Fabricius. Although the taxonomy of the group is relatively well studied, recently changes to the existing classification have been proposed without the family as currently constituted being subjected to phylogenetic analyses. In this study I present the first molecular phylogeny for this cosmopolitan family, based on three partially sequenced gene regions: 16SrRNA, 18S rRNA and 28S rRNA domain 2. Analyses resolved relationships between and within genera and subgenera that are largely congruent with existing taxonomic hypotheses based on morphology. I recovered four well-supported radiations: Polynoncus, Omorgus, Holarctic Trox and Afrotropical Phoberus. One of the more surprising results was the monophyly of Phoberus. Based on the evidence, I propose reinstating the genus Phoberus to accommodate all Afrotropical (including Madagascan endemic) species. The results re-emphasise the validity of Scholtz’s (1986a) classification system for the genus Omorgusand its subgeneraand provide evidence of an African origin for Madagascan trogids. Divergence analysis was able to date the major events for the origin of extant lineages of Trogidae. The subsequent diversification of the major lineages is largely attributed to Pangaean and Gondwanan vicariance events in the Mid-Jurassic and early Late Cretaceous, respectively. The separation of the landmasses resulted in the evolution of four distinct groups: Omorgus, Polynoncus, Trox and Phoberus. The monophyletic subgenus Phoberus MacLeay is of particular interest; about one-third (14 of 40) of the species in the Afrotropical region have lost the ability to fly. To gain insights into the evolution of flightlessness in this clade, phylogenetic relationships among species were inferred using molecular sequence data. Four partial sequences of four genes (COI, 16S, 18S and 28S domain 2) were obtained for 27 species, covering all of the recognised species-groups. Estimated times of divergence were based on published mutation rates for COI. The results recovered eight monophyletic lineages, supporting the morphology-based subdivisions of the genus. Flightlessness evolved at least five times within the subgenus. There is no strong support for the re-acquisition of functional wings once they are lost. Diversification, and the present relictual distributions, in African Phoberus can be linked to climatic and geological events associated with the Miocene and Pliocene Climate Optimum in southern Africa. The evolution of flightlessness in Phoberus is consistent with the habitat stability hypothesis. All flightless species occupy refugial areas with relatively long-term environmental stability. Phoberus is a promising model group for studying evolutionary trends relating to flightlessness, speciation and biogeography. Flightlessness is a counterintuitive evolutionary development, given the many advantages of flight. To interpret the diversification in the flightless Phoberus capensis Scholtz, the phylogenetic relationships among several populations of P. capensis are investigated. Phylogenetic relationships among populations were inferred using molecular sequence data that suggested three distinct evolutionary lineages, which was also supported by morphological characters. Divergence time estimates suggest a Pliocene-Pleistocene diversification. Based on these results, it is suggested that P. capensis experienced climatically-driven allopatric speciation with sheltered Afrotemperate forests and high mountain peaks serving as important refugia in response to climatic exacerbations. The P. capensis complex thus represents a speciation process in which flight-restricted populations evolved in close allopatry, possibly as recently as the Pleistocene. Two of the three divergent and geographically distinct lineages are described as novel species. This study represents the most recent comprehensive work on the Trogidae. On the basis of this study, it is proposed that taxonomic changes to the generic classification of the family be made. Trogidae are formally divided into two subfamilies, Omorginae and Troginae. The subgenus Phoberus is restored to genus rank to include all the Afrotropical species, and Afromorgus is confirmed at subgeneric rank. The genus Madagatrox is synonymised with Phoberus.
- Full Text:
- Date Issued: 2016
- Authors: Strümpher, Werner Petrus
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/1232 , vital:20037
- Description: Trogidae constitute a monophyletic and biologically unique family within the Scarabaeoidea, being the only keratinophagous group in its superfamily. Traditionally, the family has been divided into three distinctive genera, Omorgus Erichson, Polynoncus Burmeister, and Trox Fabricius. Although the taxonomy of the group is relatively well studied, recently changes to the existing classification have been proposed without the family as currently constituted being subjected to phylogenetic analyses. In this study I present the first molecular phylogeny for this cosmopolitan family, based on three partially sequenced gene regions: 16SrRNA, 18S rRNA and 28S rRNA domain 2. Analyses resolved relationships between and within genera and subgenera that are largely congruent with existing taxonomic hypotheses based on morphology. I recovered four well-supported radiations: Polynoncus, Omorgus, Holarctic Trox and Afrotropical Phoberus. One of the more surprising results was the monophyly of Phoberus. Based on the evidence, I propose reinstating the genus Phoberus to accommodate all Afrotropical (including Madagascan endemic) species. The results re-emphasise the validity of Scholtz’s (1986a) classification system for the genus Omorgusand its subgeneraand provide evidence of an African origin for Madagascan trogids. Divergence analysis was able to date the major events for the origin of extant lineages of Trogidae. The subsequent diversification of the major lineages is largely attributed to Pangaean and Gondwanan vicariance events in the Mid-Jurassic and early Late Cretaceous, respectively. The separation of the landmasses resulted in the evolution of four distinct groups: Omorgus, Polynoncus, Trox and Phoberus. The monophyletic subgenus Phoberus MacLeay is of particular interest; about one-third (14 of 40) of the species in the Afrotropical region have lost the ability to fly. To gain insights into the evolution of flightlessness in this clade, phylogenetic relationships among species were inferred using molecular sequence data. Four partial sequences of four genes (COI, 16S, 18S and 28S domain 2) were obtained for 27 species, covering all of the recognised species-groups. Estimated times of divergence were based on published mutation rates for COI. The results recovered eight monophyletic lineages, supporting the morphology-based subdivisions of the genus. Flightlessness evolved at least five times within the subgenus. There is no strong support for the re-acquisition of functional wings once they are lost. Diversification, and the present relictual distributions, in African Phoberus can be linked to climatic and geological events associated with the Miocene and Pliocene Climate Optimum in southern Africa. The evolution of flightlessness in Phoberus is consistent with the habitat stability hypothesis. All flightless species occupy refugial areas with relatively long-term environmental stability. Phoberus is a promising model group for studying evolutionary trends relating to flightlessness, speciation and biogeography. Flightlessness is a counterintuitive evolutionary development, given the many advantages of flight. To interpret the diversification in the flightless Phoberus capensis Scholtz, the phylogenetic relationships among several populations of P. capensis are investigated. Phylogenetic relationships among populations were inferred using molecular sequence data that suggested three distinct evolutionary lineages, which was also supported by morphological characters. Divergence time estimates suggest a Pliocene-Pleistocene diversification. Based on these results, it is suggested that P. capensis experienced climatically-driven allopatric speciation with sheltered Afrotemperate forests and high mountain peaks serving as important refugia in response to climatic exacerbations. The P. capensis complex thus represents a speciation process in which flight-restricted populations evolved in close allopatry, possibly as recently as the Pleistocene. Two of the three divergent and geographically distinct lineages are described as novel species. This study represents the most recent comprehensive work on the Trogidae. On the basis of this study, it is proposed that taxonomic changes to the generic classification of the family be made. Trogidae are formally divided into two subfamilies, Omorginae and Troginae. The subgenus Phoberus is restored to genus rank to include all the Afrotropical species, and Afromorgus is confirmed at subgeneric rank. The genus Madagatrox is synonymised with Phoberus.
- Full Text:
- Date Issued: 2016
Predators of aerial insects and riparian cross-boundary trophic dynamics: web-building spiders, dragonflies and damselflies
- Authors: Chari, Lenin Dzibakwe
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55791 , vital:26734
- Description: This thesis characterises the cross-boundary trophic interactions of a relatively small model ecosystem, the Kowie River (Eastern Cape of South Africa), to explore their epistemic implications for systems ecology. Using web-building spiders and odonates (dragonflies and damselflies) as model organisms, I sought to investigate whether the diets of predators of aerial insects could be used to assess the strength of the trophic connectivity between freshwater and terrestrial systems in relation to variables such as stream width, distance from the river and aquatic insect emergence rates and abundances. Predator diet composition was determined by using a combination of diet analysis tools: direct observations of cross-subsidies, naturally-abundant stable (carbon and nitrogen) isotope analysis and fatty acid analysis. I also sought to reveal feeding niches and guilds among riparian aerial predators and investigate how the environment influenced predators’ access to aquatic prey subsidies. As emergent aquatic insect abundances decreased with an increase in distance from the river, and increased with stream width and seasonal changes from winter to summer, stable isotope and fatty acid analyses revealed distinct changes in web-building spider diet composition. Examination of the fatty acid eicosapentaenoic acid, a component commonly used as an indicator of consumer reliance on aquatic nutritional subsidies, showed that aquatic subsidies extended further inland at the wider sections of the river. Spiders and odonates at the wider sections of the Kowie River generally received more subsidies (56 – 70%) than those at the narrower sections (25 – 60%). When terrestrial insect biomass was distinctly low in winter, the benefit of aquatic subsidisation to spiders was relatively lower at the narrower sections of the Kowie River relative to the wide sections. As such, riparian areas adjacent to wide parts of the river were more likely to support larger populations of aerial predators than those at the narrow sections. Apart from the diet changes across time and space, there was evidence of inter-specific niche partitioning in both spiders and odonates, but no differences were observed between males and females of the same species. Results showed odonates of different sizes and hunting strategies had separate dietary niches, hence varied access to aquatic nutritional subsidies. The larger odonate taxa that frequently foraged mid-air had more varied diets and relied less on aquatic emergent insects than the smaller odonates that foraged from perches near the river. There was also evidence of niche partitioning amongst the spiders, as those that built horizontal webs captured more aquatic insects (40 – 78%) than the vertical orb-web builders (20 – 66%). This study showed that the nature and extent of trophic cross-boundary linkages in riparian areas largely depended on the availability of subsidies that varied seasonally and spatially. The width of the stream and seasonal variability emerged as important predictors of emergent insect abundances/biomasses that influenced predator feeding niches. The high mobility of odonates made their reliance on aquatic nutritional subsidies different from the less mobile spiders. The link between the width of the river and the extent of trophic connectivity has implications for riparian area management and definition of riparian buffer zones. However, the variation in diet niches amongst terrestrial consumers makes the results area-specific, and more studies are required that incorporate additional terrestrial predators in other fluvial systems so that we can make some generalizations on the dynamics of riparian trophic cross-boundary links.
- Full Text:
- Date Issued: 2016
- Authors: Chari, Lenin Dzibakwe
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/55791 , vital:26734
- Description: This thesis characterises the cross-boundary trophic interactions of a relatively small model ecosystem, the Kowie River (Eastern Cape of South Africa), to explore their epistemic implications for systems ecology. Using web-building spiders and odonates (dragonflies and damselflies) as model organisms, I sought to investigate whether the diets of predators of aerial insects could be used to assess the strength of the trophic connectivity between freshwater and terrestrial systems in relation to variables such as stream width, distance from the river and aquatic insect emergence rates and abundances. Predator diet composition was determined by using a combination of diet analysis tools: direct observations of cross-subsidies, naturally-abundant stable (carbon and nitrogen) isotope analysis and fatty acid analysis. I also sought to reveal feeding niches and guilds among riparian aerial predators and investigate how the environment influenced predators’ access to aquatic prey subsidies. As emergent aquatic insect abundances decreased with an increase in distance from the river, and increased with stream width and seasonal changes from winter to summer, stable isotope and fatty acid analyses revealed distinct changes in web-building spider diet composition. Examination of the fatty acid eicosapentaenoic acid, a component commonly used as an indicator of consumer reliance on aquatic nutritional subsidies, showed that aquatic subsidies extended further inland at the wider sections of the river. Spiders and odonates at the wider sections of the Kowie River generally received more subsidies (56 – 70%) than those at the narrower sections (25 – 60%). When terrestrial insect biomass was distinctly low in winter, the benefit of aquatic subsidisation to spiders was relatively lower at the narrower sections of the Kowie River relative to the wide sections. As such, riparian areas adjacent to wide parts of the river were more likely to support larger populations of aerial predators than those at the narrow sections. Apart from the diet changes across time and space, there was evidence of inter-specific niche partitioning in both spiders and odonates, but no differences were observed between males and females of the same species. Results showed odonates of different sizes and hunting strategies had separate dietary niches, hence varied access to aquatic nutritional subsidies. The larger odonate taxa that frequently foraged mid-air had more varied diets and relied less on aquatic emergent insects than the smaller odonates that foraged from perches near the river. There was also evidence of niche partitioning amongst the spiders, as those that built horizontal webs captured more aquatic insects (40 – 78%) than the vertical orb-web builders (20 – 66%). This study showed that the nature and extent of trophic cross-boundary linkages in riparian areas largely depended on the availability of subsidies that varied seasonally and spatially. The width of the stream and seasonal variability emerged as important predictors of emergent insect abundances/biomasses that influenced predator feeding niches. The high mobility of odonates made their reliance on aquatic nutritional subsidies different from the less mobile spiders. The link between the width of the river and the extent of trophic connectivity has implications for riparian area management and definition of riparian buffer zones. However, the variation in diet niches amongst terrestrial consumers makes the results area-specific, and more studies are required that incorporate additional terrestrial predators in other fluvial systems so that we can make some generalizations on the dynamics of riparian trophic cross-boundary links.
- Full Text:
- Date Issued: 2016
Rural livelihood strategies of female headed households in former Bantustans of post-apartheid South Africa: The case of Cala, Eastern Cape Province.
- Authors: Chirau, Takunda John
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3410 , http://hdl.handle.net/10962/d1021301
- Description: Communal areas in contemporary South Africa (that is, the former Bantustans of apartheid South Africa) continue to bear and endure, albeit in new forms, socio-economic and political vulnerabilities which are negatively affecting household livelihoods. Current studies on rural livelihoods have failed to keep pace in exploring and analysing the lived experiences and ever-changing challenges faced by these rural households. This thesis provides an understanding and explanation of the livelihood activities of specifically de facto and de jure female-headed households in the former Transkei Bantustan, with a specific focus on villages in Cala. This is framed analytically by feminist theories with their emphasis on systems of patriarchy and by a rural livelihoods framework. It uses a multiplicity of research methods, including focus group discussions, in-depth interviews, life histories and survey questionnaires. The major findings of the thesis show that the female-headed households in Cala depend upon agricultural-based activities and non-agriculturally-based activities and income (including social grants) but that they exist under conditions of extreme vulnerability which are subject to fluctuation. In the end, the livelihoods of female-headed households are precarious and unstable as they live under circumstances of poverty. However, the female heads are not mere passive victims of the rural crisis in post-apartheid South Africa, as they demonstrate qualities of ingenuity and resourcefulness including through a range of coping mechanisms. At the same time, rural communities continue to be marked by patriarchal norms and practices, including systems of chieftainship, which disempower women (including female heads), though this affects de jure heads and de facto heads differently. The thesis contributes to an understanding of rural livelihoods in communal areas (or former Bantustans) of present-day South Africa by way of ‘thick descriptions’ of the everyday lives of female heads in Cala. Further, in examining rural livelihoods, it highlights the importance of bringing to bear on the livelihoods framework a feminist perspective in pinpointing the additional livelihood burdens carried by rural women.
- Full Text:
- Date Issued: 2016
- Authors: Chirau, Takunda John
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3410 , http://hdl.handle.net/10962/d1021301
- Description: Communal areas in contemporary South Africa (that is, the former Bantustans of apartheid South Africa) continue to bear and endure, albeit in new forms, socio-economic and political vulnerabilities which are negatively affecting household livelihoods. Current studies on rural livelihoods have failed to keep pace in exploring and analysing the lived experiences and ever-changing challenges faced by these rural households. This thesis provides an understanding and explanation of the livelihood activities of specifically de facto and de jure female-headed households in the former Transkei Bantustan, with a specific focus on villages in Cala. This is framed analytically by feminist theories with their emphasis on systems of patriarchy and by a rural livelihoods framework. It uses a multiplicity of research methods, including focus group discussions, in-depth interviews, life histories and survey questionnaires. The major findings of the thesis show that the female-headed households in Cala depend upon agricultural-based activities and non-agriculturally-based activities and income (including social grants) but that they exist under conditions of extreme vulnerability which are subject to fluctuation. In the end, the livelihoods of female-headed households are precarious and unstable as they live under circumstances of poverty. However, the female heads are not mere passive victims of the rural crisis in post-apartheid South Africa, as they demonstrate qualities of ingenuity and resourcefulness including through a range of coping mechanisms. At the same time, rural communities continue to be marked by patriarchal norms and practices, including systems of chieftainship, which disempower women (including female heads), though this affects de jure heads and de facto heads differently. The thesis contributes to an understanding of rural livelihoods in communal areas (or former Bantustans) of present-day South Africa by way of ‘thick descriptions’ of the everyday lives of female heads in Cala. Further, in examining rural livelihoods, it highlights the importance of bringing to bear on the livelihoods framework a feminist perspective in pinpointing the additional livelihood burdens carried by rural women.
- Full Text:
- Date Issued: 2016
Selecting and augmenting a FOSS development and deployment environment for personalized video-oriented services in a Telco context
- Authors: Shibeshi, Zelalem Sintayehu
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/943 , vital:20005
- Description: The great demand for video services on the Internet is one contributing factor that led telecom companies to search for solutions to deliver innovative video services, using the different access technologies managed by them and leveraging the capacity of enforcing Quality of Service (QoS). One part of the solution was an infrastructure that guarantees QoS for these services, in the form of the IP Multimedia Subsystem (IMS) framework. The IMS framework was developed for delivering innovative multimedia services, but IMS alone does not provide the required services. This has led to further work in the area of multimedia service architectures. One noteworthy architecture is IPTV. IPTV is more than what its name implies, as it allows the development of various innovative video-oriented services and not just tv. When IPTV was introduced, many thought that it would bring back the revenue loss that telecom companies experienced to over-the-top (OTT) service providers. However, despite all its promises, the IPTV implementation has not shown as wide an uptake as one would expect. Although there could be various reasons for the slow penetration of IPTV, one reason could be the technical challenge that IPTV poses to service developers. One of the main reasons for the embarking of the research reported in this thesis was to identify and select free and open source software (FOSS) based platforms and augment them for easy development and deployment of video-oriented services. The thesis motivated how the IPTV architecture, with some modification, can be a good architecture to develop innovative video-oriented services. For a better understanding and investigate the issues of video-oriented service development on different platforms, we followed an incremental and iterative prototyping method. As a result, various video-oriented services were first developed and implementation-related issues were analyzed. This has helped us to identify problems that service developers face, including the requirement to utilize a number of protocols to develop an IPTV-based video-oriented service and the lack of a platform that provides a consistent programming interface to implement them all. The process also helped us to identify new uses cases through the process. As part of our selection process, we found that the Mobicents service development platform can be used as the basis for a good service development and deployment environment for video-oriented services. Mobicents is a Java-based service delivery platform for quick development, deployment and management of next generation network applications. Mobicents is a good choice because it provides a consistent programming interface and supports the various protocols needed in a consistent manner or an easy way to include the support for them. We used Mobicents to compose the environment that developers can use to build video-oriented services. Specifically we developed components and service building blocks that service developer can use to develop various innovative video-oriented services. During our research, we also identified various issues with regard to support from streaming servers in general and open source streaming servers in particular and also with the protocol they use. Specifically, we identified issues with Real Time Streaming Protocol (RTSP), a protocol specified as the media control protocol in the IPTV specification, and made proposals for solving them. We developed an RSTP proxy to augment the features lacking in the current streaming servers and implemented some of the features we proposed in it.
- Full Text:
- Date Issued: 2016
- Authors: Shibeshi, Zelalem Sintayehu
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/943 , vital:20005
- Description: The great demand for video services on the Internet is one contributing factor that led telecom companies to search for solutions to deliver innovative video services, using the different access technologies managed by them and leveraging the capacity of enforcing Quality of Service (QoS). One part of the solution was an infrastructure that guarantees QoS for these services, in the form of the IP Multimedia Subsystem (IMS) framework. The IMS framework was developed for delivering innovative multimedia services, but IMS alone does not provide the required services. This has led to further work in the area of multimedia service architectures. One noteworthy architecture is IPTV. IPTV is more than what its name implies, as it allows the development of various innovative video-oriented services and not just tv. When IPTV was introduced, many thought that it would bring back the revenue loss that telecom companies experienced to over-the-top (OTT) service providers. However, despite all its promises, the IPTV implementation has not shown as wide an uptake as one would expect. Although there could be various reasons for the slow penetration of IPTV, one reason could be the technical challenge that IPTV poses to service developers. One of the main reasons for the embarking of the research reported in this thesis was to identify and select free and open source software (FOSS) based platforms and augment them for easy development and deployment of video-oriented services. The thesis motivated how the IPTV architecture, with some modification, can be a good architecture to develop innovative video-oriented services. For a better understanding and investigate the issues of video-oriented service development on different platforms, we followed an incremental and iterative prototyping method. As a result, various video-oriented services were first developed and implementation-related issues were analyzed. This has helped us to identify problems that service developers face, including the requirement to utilize a number of protocols to develop an IPTV-based video-oriented service and the lack of a platform that provides a consistent programming interface to implement them all. The process also helped us to identify new uses cases through the process. As part of our selection process, we found that the Mobicents service development platform can be used as the basis for a good service development and deployment environment for video-oriented services. Mobicents is a Java-based service delivery platform for quick development, deployment and management of next generation network applications. Mobicents is a good choice because it provides a consistent programming interface and supports the various protocols needed in a consistent manner or an easy way to include the support for them. We used Mobicents to compose the environment that developers can use to build video-oriented services. Specifically we developed components and service building blocks that service developer can use to develop various innovative video-oriented services. During our research, we also identified various issues with regard to support from streaming servers in general and open source streaming servers in particular and also with the protocol they use. Specifically, we identified issues with Real Time Streaming Protocol (RTSP), a protocol specified as the media control protocol in the IPTV specification, and made proposals for solving them. We developed an RSTP proxy to augment the features lacking in the current streaming servers and implemented some of the features we proposed in it.
- Full Text:
- Date Issued: 2016
Shifting identities: An exploration of the possibilities for a syncretic Afrikaans theatre by means of three case studies – Hex (2003), Lady Anne (2007), Ekspedisies (2008)
- Authors: Gehring, Heike
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2165 , http://hdl.handle.net/10962/d1021269
- Description: This thesis investigates the possibilities for syncretic Afrikaans language theatre within a post-1994 South African society. The research sets out to explore in what manner theatre can be language-specific, while at the same time being able to cross language contexts. This exploration is driven by the wish to develop strategies for creating Afrikaans theatre that is able to reflect on a society “united in diversity”. In this regard it is argued that for theatre to be able to both retain and cross language barriers, processes of bonding and bridging are necessary. The thesis sets out first to explain why these processes are required and then to suggest ways in which such processes can be implemented in practice. A triangular approach is used, in which conceptual and theoretical frameworks are developed to reflect on actual theatre practices. Three of my own productions are used as case studies, namely Hex (2000; 2003), Lady Anne (2007) and Ekspedisies (2008). These productions can be understood to be “boundary objects” in Henk Borgdorff’s (2012: 177) sense of the word, in that they fulfil a dual function: they are artistic productions that can also be reconstituted to serve a research purpose beyond the productions themselves. All three works were first created for public consumption before becoming cases for this thesis. Many of the strategies that were developed and tested in creating these productions are examples of ways in which bonding and bridging in Afrikaans language theatre can be understood. Chapter One of the thesis contextualises the political currents and events that necessitated the impulse towards “bonding and bridging”. In this case the political and ethical impetus behind the practical explorations has been related predominantly to the democratisation of South African society, in which a paradigm shift happened from viewing the Afrikaans language as one over many to one amongst many. Within a multilingual South Africa, concerns are raised about ways in which to create theatre in South African languages other than English (often understood to be the only possible bridging language) that are able to cross language divides. Following this introduction to language-related concerns, Chapter Two explains how the shift from apartheid to democracy made space for shifts in identity – on personal as well as institutional levels: a progression from essentialised notions of culture to the celebration of plurality. This progression is then related to theatre, with an explanation of how the post-1994 theatre landscape demanded a reimagining of the form and function of theatre. In this re-imagination the notion of a “third space” is important; something that is introduced in this chapter as an alternative to polarised identity constructions. The function of the “third space” as an in-between space and a meeting point for diverse people and entities is a strong underlying theme of this thesis and it serves as a reoccurring touchstone to the ideas put forward. Chapter Three discusses the South African arts festival culture and its contribution to the South African theatre landscape. Particular focus is placed on the Klein Karoo National Arts festival (KKNK) as a platform for the development of the Afrikaans language within a post-1994 context. What is emphasized in particular is the attempt by the KKNK festival to be linguistically and culturally exploratory and inclusive in the face of language protectionism. After the contextual background of the first three chapters, the thesis shifts to an analysis of theories related to “hybridity” and “syncretism”. In Chapter Four the argument is put forward that of the various inclusive performance and theatre models that represent a multicultural society, the most responsive forms are those that are syncretic and hybrid. Principles that can contribute to the unification and merging of diverse and polarized societal groups are described, and suggestions are made for possible ways to bring about bonding and bridging within cultural practices. Having introduced these principles, examples are offered of how these theories might be understood in other disciplines, namely, religious studies, anthropology, history and a range of cultural practices. Following this broad discussion, Chapter Five describes syncretism and hybridity more specifically in theatre by means of relevant examples. Taking the discussion further into the realm of application, Chapter Six offers an overview of “workshop theatre”, “translation” and “collage making” as strategies for putting theories of hybridity and syncretism into practice. This is followed (in Chapters Seven, Eight and Nine) by a discussion of the three productions (Hex, Lady Anne and Ekspedisies) as case studies that demonstrate how these theories can be understood in practice. Practical strategies for bridging language divides are foregrounded, such as code switching as an approach for enabling a “co-habitation” of languages; physical theatre as a means for crossing language divides; and the creation of more than one language version of a production as a tactic to accommodate shifting contexts. Following on from the discoveries made in the foregoing chapters, I conclude that theories and practices related to notions of “third space”, “hybridity” and “syncretism” are ideal for creating theatre forms (in the Afrikaans language in particular) that can truly reflect a South African society which is “united in diversity”. The thesis ends by offering suggestions for ways in which new, future identities, can be developed.
- Full Text:
- Date Issued: 2016
- Authors: Gehring, Heike
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2165 , http://hdl.handle.net/10962/d1021269
- Description: This thesis investigates the possibilities for syncretic Afrikaans language theatre within a post-1994 South African society. The research sets out to explore in what manner theatre can be language-specific, while at the same time being able to cross language contexts. This exploration is driven by the wish to develop strategies for creating Afrikaans theatre that is able to reflect on a society “united in diversity”. In this regard it is argued that for theatre to be able to both retain and cross language barriers, processes of bonding and bridging are necessary. The thesis sets out first to explain why these processes are required and then to suggest ways in which such processes can be implemented in practice. A triangular approach is used, in which conceptual and theoretical frameworks are developed to reflect on actual theatre practices. Three of my own productions are used as case studies, namely Hex (2000; 2003), Lady Anne (2007) and Ekspedisies (2008). These productions can be understood to be “boundary objects” in Henk Borgdorff’s (2012: 177) sense of the word, in that they fulfil a dual function: they are artistic productions that can also be reconstituted to serve a research purpose beyond the productions themselves. All three works were first created for public consumption before becoming cases for this thesis. Many of the strategies that were developed and tested in creating these productions are examples of ways in which bonding and bridging in Afrikaans language theatre can be understood. Chapter One of the thesis contextualises the political currents and events that necessitated the impulse towards “bonding and bridging”. In this case the political and ethical impetus behind the practical explorations has been related predominantly to the democratisation of South African society, in which a paradigm shift happened from viewing the Afrikaans language as one over many to one amongst many. Within a multilingual South Africa, concerns are raised about ways in which to create theatre in South African languages other than English (often understood to be the only possible bridging language) that are able to cross language divides. Following this introduction to language-related concerns, Chapter Two explains how the shift from apartheid to democracy made space for shifts in identity – on personal as well as institutional levels: a progression from essentialised notions of culture to the celebration of plurality. This progression is then related to theatre, with an explanation of how the post-1994 theatre landscape demanded a reimagining of the form and function of theatre. In this re-imagination the notion of a “third space” is important; something that is introduced in this chapter as an alternative to polarised identity constructions. The function of the “third space” as an in-between space and a meeting point for diverse people and entities is a strong underlying theme of this thesis and it serves as a reoccurring touchstone to the ideas put forward. Chapter Three discusses the South African arts festival culture and its contribution to the South African theatre landscape. Particular focus is placed on the Klein Karoo National Arts festival (KKNK) as a platform for the development of the Afrikaans language within a post-1994 context. What is emphasized in particular is the attempt by the KKNK festival to be linguistically and culturally exploratory and inclusive in the face of language protectionism. After the contextual background of the first three chapters, the thesis shifts to an analysis of theories related to “hybridity” and “syncretism”. In Chapter Four the argument is put forward that of the various inclusive performance and theatre models that represent a multicultural society, the most responsive forms are those that are syncretic and hybrid. Principles that can contribute to the unification and merging of diverse and polarized societal groups are described, and suggestions are made for possible ways to bring about bonding and bridging within cultural practices. Having introduced these principles, examples are offered of how these theories might be understood in other disciplines, namely, religious studies, anthropology, history and a range of cultural practices. Following this broad discussion, Chapter Five describes syncretism and hybridity more specifically in theatre by means of relevant examples. Taking the discussion further into the realm of application, Chapter Six offers an overview of “workshop theatre”, “translation” and “collage making” as strategies for putting theories of hybridity and syncretism into practice. This is followed (in Chapters Seven, Eight and Nine) by a discussion of the three productions (Hex, Lady Anne and Ekspedisies) as case studies that demonstrate how these theories can be understood in practice. Practical strategies for bridging language divides are foregrounded, such as code switching as an approach for enabling a “co-habitation” of languages; physical theatre as a means for crossing language divides; and the creation of more than one language version of a production as a tactic to accommodate shifting contexts. Following on from the discoveries made in the foregoing chapters, I conclude that theories and practices related to notions of “third space”, “hybridity” and “syncretism” are ideal for creating theatre forms (in the Afrikaans language in particular) that can truly reflect a South African society which is “united in diversity”. The thesis ends by offering suggestions for ways in which new, future identities, can be developed.
- Full Text:
- Date Issued: 2016
Structural bioinformatics studies and tool development related to drug discovery
- Authors: Hatherley, Rowan
- Date: 2016
- Subjects: Structural bioinformatics , Drug development , Natural products -- Databases , Natural products -- Biotechnology , Sequence alignment (Bioinformatics) , Malaria -- Chemotherapy , Heat shock proteins , Plasmodium falciparum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4164 , http://hdl.handle.net/10962/d1020021
- Description: This thesis is divided into two distinct sections which can be combined under the broad umbrella of structural bioinformatics studies related to drug discovery. The first section involves the establishment of an online South African natural products database. Natural products (NPs) are chemical entities synthesised in nature and are unrivalled in their structural complexity, chemical diversity, and biological specificity, which has long made them crucial to the drug discovery process. South Africa is rich in both plant and marine biodiversity and a great deal of research has gone into isolating compounds from organisms found in this country. However, there is no official database containing this information, making it difficult to access for research purposes. This information was extracted manually from literature to create a database of South African natural products. In order to make the information accessible to the general research community, a website, named “SANCDB”, was built to enable compounds to be quickly and easily searched for and downloaded in a number of different chemical formats. The content of the database was assessed and compared to other established natural product databases. Currently, SANCDB is the only database of natural products in Africa with an online interface. The second section of the thesis was aimed at performing structural characterisation of proteins with the potential to be targeted for antimalarial drug therapy. This looked specifically at 1) The interactions between an exported heat shock protein (Hsp) from Plasmodium falciparum (P. falciparum), PfHsp70-x and various host and exported parasite J proteins, as well as 2) The interface between PfHsp90 and the heat shock organising protein (PfHop). The PfHsp70-x:J protein study provided additional insight into how these two proteins potentially interact. Analysis of the PfHsp90:PfHop also provided a structural insight into the interaction interface between these two proteins and identified residues that could be targeted due to their contribution to the stability of the Hsp90:Hop binding complex and differences between parasite and human proteins. These studies inspired the development of a homology modelling tool, which can be used to assist researchers with homology modelling, while providing them with step-by-step control over the entire process. This thesis presents the establishment of a South African NP database and the development of a homology modelling tool, inspired by protein structural studies. When combined, these two applications have the potential to contribute greatly towards in silico drug discovery research.
- Full Text:
- Date Issued: 2016
- Authors: Hatherley, Rowan
- Date: 2016
- Subjects: Structural bioinformatics , Drug development , Natural products -- Databases , Natural products -- Biotechnology , Sequence alignment (Bioinformatics) , Malaria -- Chemotherapy , Heat shock proteins , Plasmodium falciparum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4164 , http://hdl.handle.net/10962/d1020021
- Description: This thesis is divided into two distinct sections which can be combined under the broad umbrella of structural bioinformatics studies related to drug discovery. The first section involves the establishment of an online South African natural products database. Natural products (NPs) are chemical entities synthesised in nature and are unrivalled in their structural complexity, chemical diversity, and biological specificity, which has long made them crucial to the drug discovery process. South Africa is rich in both plant and marine biodiversity and a great deal of research has gone into isolating compounds from organisms found in this country. However, there is no official database containing this information, making it difficult to access for research purposes. This information was extracted manually from literature to create a database of South African natural products. In order to make the information accessible to the general research community, a website, named “SANCDB”, was built to enable compounds to be quickly and easily searched for and downloaded in a number of different chemical formats. The content of the database was assessed and compared to other established natural product databases. Currently, SANCDB is the only database of natural products in Africa with an online interface. The second section of the thesis was aimed at performing structural characterisation of proteins with the potential to be targeted for antimalarial drug therapy. This looked specifically at 1) The interactions between an exported heat shock protein (Hsp) from Plasmodium falciparum (P. falciparum), PfHsp70-x and various host and exported parasite J proteins, as well as 2) The interface between PfHsp90 and the heat shock organising protein (PfHop). The PfHsp70-x:J protein study provided additional insight into how these two proteins potentially interact. Analysis of the PfHsp90:PfHop also provided a structural insight into the interaction interface between these two proteins and identified residues that could be targeted due to their contribution to the stability of the Hsp90:Hop binding complex and differences between parasite and human proteins. These studies inspired the development of a homology modelling tool, which can be used to assist researchers with homology modelling, while providing them with step-by-step control over the entire process. This thesis presents the establishment of a South African NP database and the development of a homology modelling tool, inspired by protein structural studies. When combined, these two applications have the potential to contribute greatly towards in silico drug discovery research.
- Full Text:
- Date Issued: 2016
Synthesis and biological evaluation of novel thiazole-based compounds
- Authors: Olawode, Emmanual Oladayo
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62955 , vital:28325
- Description: Thesis embargoed for one-year period. Expected date of release: April 2019
- Full Text:
- Date Issued: 2016
- Authors: Olawode, Emmanual Oladayo
- Date: 2016
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62955 , vital:28325
- Description: Thesis embargoed for one-year period. Expected date of release: April 2019
- Full Text:
- Date Issued: 2016
Synthesis and exploration of resorcinol derivatives as Plasmodium falciparum Hsp90 inhibitors
- Authors: Umumararungu, Théoneste
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/717 , vital:19984
- Description: In this research project, we have synthesized a series of nine dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38, a potent Hsp90 inhibitor. These analogues were chosen because they share the same pharmacophore with NMS-E973 (L-1) 38 and were thus expected to have a similar biological activity. Moreover, it is generally easier to synthesize the dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38 as compared to their demethylated counterparts. Since other Hsp90 inhibitors such as geldanamycin 19 have demonstrated anti-plasmodial activity, we also expected our compounds to be Hsp90 inhibitors and to possess anti-plasmodial activity. However, our compounds were tested for growth inhibitory activity of Plasmodium falciparum and not for P. falciparum Hsp90 (PfHSP90) inhibitory activity. The synthesis involved a series of steps that led to the formation of the ester compound TU-011 (L-7) 43 that was then used as a precursor for different NMS-E973 (L-1) 38 analogues. The choice of analogues to be synthesized was dictated by binding affinity predictions obtained from molecular docking. The chosen synthetic analogues were active against chloroquine-sensitive Plasmodium falciparum (3D7 strain) in a Plasmodium lactate dehydrogenase assay and they were not generally cytotoxic to human cervical adenocarcinoma cell line HeLa. The most active of our compounds was TU-018 (L-103) 50 with an IC50 value of approximately 1.830 µM as compared to the standard, chloroquine, with an IC50 value of 0.01062 µM. Some of the compounds showed mild cytotoxicity towards HeLa cells with IC50 values higher than 25 µM as compared to the standard apoptosis inducer drug, emetine that had an IC50 value of 0.09948 µM. These results highlight the fact that the synthesized analogues are novel relatively non-toxic anti-plasmodial agents.
- Full Text:
- Date Issued: 2016
- Authors: Umumararungu, Théoneste
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/717 , vital:19984
- Description: In this research project, we have synthesized a series of nine dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38, a potent Hsp90 inhibitor. These analogues were chosen because they share the same pharmacophore with NMS-E973 (L-1) 38 and were thus expected to have a similar biological activity. Moreover, it is generally easier to synthesize the dimethyl ether resorcinol analogues of NMS-E973 (L-1) 38 as compared to their demethylated counterparts. Since other Hsp90 inhibitors such as geldanamycin 19 have demonstrated anti-plasmodial activity, we also expected our compounds to be Hsp90 inhibitors and to possess anti-plasmodial activity. However, our compounds were tested for growth inhibitory activity of Plasmodium falciparum and not for P. falciparum Hsp90 (PfHSP90) inhibitory activity. The synthesis involved a series of steps that led to the formation of the ester compound TU-011 (L-7) 43 that was then used as a precursor for different NMS-E973 (L-1) 38 analogues. The choice of analogues to be synthesized was dictated by binding affinity predictions obtained from molecular docking. The chosen synthetic analogues were active against chloroquine-sensitive Plasmodium falciparum (3D7 strain) in a Plasmodium lactate dehydrogenase assay and they were not generally cytotoxic to human cervical adenocarcinoma cell line HeLa. The most active of our compounds was TU-018 (L-103) 50 with an IC50 value of approximately 1.830 µM as compared to the standard, chloroquine, with an IC50 value of 0.01062 µM. Some of the compounds showed mild cytotoxicity towards HeLa cells with IC50 values higher than 25 µM as compared to the standard apoptosis inducer drug, emetine that had an IC50 value of 0.09948 µM. These results highlight the fact that the synthesized analogues are novel relatively non-toxic anti-plasmodial agents.
- Full Text:
- Date Issued: 2016
Synthesis of chiral ketopinic acid-derived catalysts and their evaluation in asymmetric transformations
- Authors: Hassan, Yusuf
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/550 , vital:19969
- Description: Four new (+)-ketopinic acid-derived Mn(III) complexes, three of which possess pseudo C2- symmetry, were synthesised as chiral catalyst candidates. The ligands were prepared by refluxing (+)-ketopinic acid with ethane-1,2-diamine, the resolved (R,R)- and (S,S)-1,2-diaminocyclohexanes, and 1,2-diaminobenzene in chloroform. Treatment of the ligands with manganese(II) acetate tetrahydrate in refluxing ethanol afforded the respective complexes as brown amorphous powders. Characterisation of the ligands and the corresponding complexes was achieved using 1-D and 2-D NMR, IR spectroscopy, and elemental analysis. Various homogeneous asymmetric transformations, were investigated using these four complexes, viz., aldol, and Baylis-Hillman reactions, aza-Michael addition of piperidine to the Baylis-Hillman adducts, epoxidation, and ketone and imine reduction. Asymmetric aldol reactions of benzaldehyde with the aryl ketones, acetophenone, propiophenone, -tetralone, 4-nitroacetophenone, and 4-methoxyacetophenone, conducted in the presence of 10 mole % of the chiral catalysts, afforded enantioselectivities of up to 99% e.e. Asymmetric Baylis-Hillman reactions of methyl- and tert-butyl acrylates with pyridine-2- carbaldehyde, 6-methylpyridine-2-carbaldehyde, 5-chlorosalicylaldehyde, benzaldehyde, 4-chlorobenzaldehyde, and 2-nitrobenzaldehyde were conducted in the presence of catalyst 139 (10 mole %) to afford enantioselectivities of up to 44% e.e. Aza-Michael addition of piperidine to racemic Baylis- Hillman adducts in the presence of the catalyst 139 (10 mole %) was found to proceed with diastereoselectivities of up to 91% d.e. Asymmetric epoxidation of trans-methyl styrene, styrene, trans-stilbene, cis-stilbene, and indene, using a 5 mole % chiral catalyst loading and m-CPBA as the oxygen source, gave enantioselectivities of up to 32 % e.e. Asymmetric reductions of acetophenone, 3-chloropropiophenone, 4-hydroxyacetophenone, -tetralone, and 2-hydroxy-1-acetonapthone were investigated using NaBH4 as the reducing agent and a 10 mole % loading of the chiral catalysts. A stereoselectivity of 68% e.e. was obtained in the reduction of acetophenone, but attempts to reduce the selected imines to the corresponding chiral amines proved to be unsuccessful — even in the absence of the catalysts. It thus became apparent that the catalytic version of the reaction was not feasible.
- Full Text:
- Date Issued: 2016
- Authors: Hassan, Yusuf
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/550 , vital:19969
- Description: Four new (+)-ketopinic acid-derived Mn(III) complexes, three of which possess pseudo C2- symmetry, were synthesised as chiral catalyst candidates. The ligands were prepared by refluxing (+)-ketopinic acid with ethane-1,2-diamine, the resolved (R,R)- and (S,S)-1,2-diaminocyclohexanes, and 1,2-diaminobenzene in chloroform. Treatment of the ligands with manganese(II) acetate tetrahydrate in refluxing ethanol afforded the respective complexes as brown amorphous powders. Characterisation of the ligands and the corresponding complexes was achieved using 1-D and 2-D NMR, IR spectroscopy, and elemental analysis. Various homogeneous asymmetric transformations, were investigated using these four complexes, viz., aldol, and Baylis-Hillman reactions, aza-Michael addition of piperidine to the Baylis-Hillman adducts, epoxidation, and ketone and imine reduction. Asymmetric aldol reactions of benzaldehyde with the aryl ketones, acetophenone, propiophenone, -tetralone, 4-nitroacetophenone, and 4-methoxyacetophenone, conducted in the presence of 10 mole % of the chiral catalysts, afforded enantioselectivities of up to 99% e.e. Asymmetric Baylis-Hillman reactions of methyl- and tert-butyl acrylates with pyridine-2- carbaldehyde, 6-methylpyridine-2-carbaldehyde, 5-chlorosalicylaldehyde, benzaldehyde, 4-chlorobenzaldehyde, and 2-nitrobenzaldehyde were conducted in the presence of catalyst 139 (10 mole %) to afford enantioselectivities of up to 44% e.e. Aza-Michael addition of piperidine to racemic Baylis- Hillman adducts in the presence of the catalyst 139 (10 mole %) was found to proceed with diastereoselectivities of up to 91% d.e. Asymmetric epoxidation of trans-methyl styrene, styrene, trans-stilbene, cis-stilbene, and indene, using a 5 mole % chiral catalyst loading and m-CPBA as the oxygen source, gave enantioselectivities of up to 32 % e.e. Asymmetric reductions of acetophenone, 3-chloropropiophenone, 4-hydroxyacetophenone, -tetralone, and 2-hydroxy-1-acetonapthone were investigated using NaBH4 as the reducing agent and a 10 mole % loading of the chiral catalysts. A stereoselectivity of 68% e.e. was obtained in the reduction of acetophenone, but attempts to reduce the selected imines to the corresponding chiral amines proved to be unsuccessful — even in the absence of the catalysts. It thus became apparent that the catalytic version of the reaction was not feasible.
- Full Text:
- Date Issued: 2016
The chemistry of Algoa Bay ascidians
- Authors: Bromley, Candice Leigh
- Date: 2016
- Subjects: Sea squirts -- South Africa -- Algoa Bay , Marine metabolites , Chemistry, Analytic , Liquid chromatography , Inductively coupled plasma mass spectrometry , Metal ions , Nucleosides , Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4560 , http://hdl.handle.net/10962/d1020606
- Description: This thesis investigates the chemistry of 25 ascidian species collected from Algoa Bay, South Africa with a concerted focus on metal accumulation by these ascidians and the possible interaction of these metals with ascidian metabolites. Chapter 2 details the screening techniques employed to establish the presence of nitrogenous metabolites (1H- 15N HMBC), hyper-accumulated metal ions (ICP-MS) and potential metal ion/ ascidian metabolite complexes (LC-ICP-MS/ESI-MS). Unfortunately, exhaustive attempts to detect intact metal ion/ascidian metabolite complexes through the use of liquid chromatography with parallel inductively coupled plasma mass spectrometry/electrospray mass spectrometry (LC-ICPMS/ ESI-MS) were unsuccessful. However, the LC-ICP-MS/ESI-MS data obtained for the crude organic extracts of six of the Algoa Bay ascidian species, Distaplia skoogi, Aplidium monile, Aplidium sp., Didemnum sp., Leptoclindines sp. and Polycitor sp. enabled identification of a number of ten halogenated metabolites, namely the indoles 2.28-2.30, and the tyramine and tyrosine derivatives (2.31-2.33, 2.41, 2.43, 2.44 and 2.46), within the ascidian extracts. This study confirmed that LC-ICP-MS/ESI-MS is a powerful tool for the dereplication of halogenated metabolites in complex mixtures especially where these compounds are present in very small amounts. This study is also the first report of these compounds (eight of which are known) in African ascidians. Compounds 2.32 and 2.46 have not been reported before from a marine source. Compounds 2.28-2.30 and 2.33 were present in sufficient amounts in the respective ascidian extracts to allow their isolation and structure elucidation using standard spectroscopic techniques Chapter 3 explores the ability of ascidians to accumulate a wide range of metal ions at concentrations which are often orders of magnitude higher than those of the surrounding sea water. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the total ion concentrations of 24 metals in 25 Algoa Bay ascidian species. To the best of our knowledge this is the largest and most extensive investigation of metal concentrations in a group of different ascidians occurring in the same area. Hypotheisizing that the metal ion concentrations for each ascidian specimen screened may represent a unique fingerprint for each specimen principal component analysis (PCA) was used in an attempt to establish whether there were spatial, temporal or phylogenetic relationships associated with the metal concentration fingerprints of the ascidians that formed part of this study. The PCA results showed that there were no statistically significant relationships between ascidian metal ion concentrations and either the collection year or the collection site of the ascidians. However, species from the family Didemnidae provided the clearest statistical evidence supporting a phylogenetic relationship between these ascidians and their hyperaccumulated metal ion profiles. Furthermore, these results suggested that ascidian species are indeed actively concentrating metal ions from the surrounding sea water and are not simply sinks for passively accumulated metal ions. Interestingly, the concentration of vanadium in the set of ascidians studied did not appear to correlate with any of the other metals accumulated by these ascidians suggesting that there is possibly a unique method employed for the accumulation of vanadium by ascidians. Chapter 4 investigated this possibility further after the nucleosides 4.10, 4.11, 4.13, 4.15, 4.17 and 4.40 were isolated from the vanadium accumulating ascidian Aplidium monile. Studies into the interactions between nucleosides and vanadyl are unfortunately rare and usually qualitative in nature with limited information provided about the stability or structures of the complexes formed. The vanadyl accumulating aplousobranch ascidians e.g. Aplidium monile dominated our study of Algoa Bay ascidians therefore providing us with the rationale to investigate the relatively little studied binding ability and stability of vandyl-nucleoside complexes. Potentiometric studies were conducted to determine the stability constants of complexes formed between the oxovanadium ion vanadyl (VO2+) and the commercially available nucleosides 4.10-4.14. The data afforded by this analysis clearly confirmed the complexity of the vanadyl/nucleoside complexation and suggested that guanosine (4.12) formed the most stable complex with oxovanadium ions. We were also able to establish a third protonation constant for the hydroxyl moiety in 4.12 with a logK 8.87 which has not been previously reported. Finally, Chapter 5 revisited the cytoxicity two Algoa Bay ascidians, Clavelina sp. and Atriolum marinense the extracts from which produced promising bioactivity results in previous studies against oesophageal cancer cells. The HP-20 fractionated extracts of Clavelina sp. and Atriolum marinense proved to be similalrly cytotoxic to breast cancer cells. With the exception for the 100% acetone(aq)fractions the NMR data for both species suggested that most active non polar fractions were dominated by what appeared to be structurally unremarkable fatty acid glycerides and as such were not pursued further. Purification of the 100% acetone(aq)fraction of A. marinense resulted in the isolation of a styrene trimer, 5.1, common to both ascidian extracts. The NMR simulation software WIN-DAISY was employed to confirm the structure of 5.1. Attempts to establish if 5.1 was an isolation artefact or a product of marine pollution were inconclusive
- Full Text:
- Date Issued: 2016
- Authors: Bromley, Candice Leigh
- Date: 2016
- Subjects: Sea squirts -- South Africa -- Algoa Bay , Marine metabolites , Chemistry, Analytic , Liquid chromatography , Inductively coupled plasma mass spectrometry , Metal ions , Nucleosides , Vanadium
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4560 , http://hdl.handle.net/10962/d1020606
- Description: This thesis investigates the chemistry of 25 ascidian species collected from Algoa Bay, South Africa with a concerted focus on metal accumulation by these ascidians and the possible interaction of these metals with ascidian metabolites. Chapter 2 details the screening techniques employed to establish the presence of nitrogenous metabolites (1H- 15N HMBC), hyper-accumulated metal ions (ICP-MS) and potential metal ion/ ascidian metabolite complexes (LC-ICP-MS/ESI-MS). Unfortunately, exhaustive attempts to detect intact metal ion/ascidian metabolite complexes through the use of liquid chromatography with parallel inductively coupled plasma mass spectrometry/electrospray mass spectrometry (LC-ICPMS/ ESI-MS) were unsuccessful. However, the LC-ICP-MS/ESI-MS data obtained for the crude organic extracts of six of the Algoa Bay ascidian species, Distaplia skoogi, Aplidium monile, Aplidium sp., Didemnum sp., Leptoclindines sp. and Polycitor sp. enabled identification of a number of ten halogenated metabolites, namely the indoles 2.28-2.30, and the tyramine and tyrosine derivatives (2.31-2.33, 2.41, 2.43, 2.44 and 2.46), within the ascidian extracts. This study confirmed that LC-ICP-MS/ESI-MS is a powerful tool for the dereplication of halogenated metabolites in complex mixtures especially where these compounds are present in very small amounts. This study is also the first report of these compounds (eight of which are known) in African ascidians. Compounds 2.32 and 2.46 have not been reported before from a marine source. Compounds 2.28-2.30 and 2.33 were present in sufficient amounts in the respective ascidian extracts to allow their isolation and structure elucidation using standard spectroscopic techniques Chapter 3 explores the ability of ascidians to accumulate a wide range of metal ions at concentrations which are often orders of magnitude higher than those of the surrounding sea water. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the total ion concentrations of 24 metals in 25 Algoa Bay ascidian species. To the best of our knowledge this is the largest and most extensive investigation of metal concentrations in a group of different ascidians occurring in the same area. Hypotheisizing that the metal ion concentrations for each ascidian specimen screened may represent a unique fingerprint for each specimen principal component analysis (PCA) was used in an attempt to establish whether there were spatial, temporal or phylogenetic relationships associated with the metal concentration fingerprints of the ascidians that formed part of this study. The PCA results showed that there were no statistically significant relationships between ascidian metal ion concentrations and either the collection year or the collection site of the ascidians. However, species from the family Didemnidae provided the clearest statistical evidence supporting a phylogenetic relationship between these ascidians and their hyperaccumulated metal ion profiles. Furthermore, these results suggested that ascidian species are indeed actively concentrating metal ions from the surrounding sea water and are not simply sinks for passively accumulated metal ions. Interestingly, the concentration of vanadium in the set of ascidians studied did not appear to correlate with any of the other metals accumulated by these ascidians suggesting that there is possibly a unique method employed for the accumulation of vanadium by ascidians. Chapter 4 investigated this possibility further after the nucleosides 4.10, 4.11, 4.13, 4.15, 4.17 and 4.40 were isolated from the vanadium accumulating ascidian Aplidium monile. Studies into the interactions between nucleosides and vanadyl are unfortunately rare and usually qualitative in nature with limited information provided about the stability or structures of the complexes formed. The vanadyl accumulating aplousobranch ascidians e.g. Aplidium monile dominated our study of Algoa Bay ascidians therefore providing us with the rationale to investigate the relatively little studied binding ability and stability of vandyl-nucleoside complexes. Potentiometric studies were conducted to determine the stability constants of complexes formed between the oxovanadium ion vanadyl (VO2+) and the commercially available nucleosides 4.10-4.14. The data afforded by this analysis clearly confirmed the complexity of the vanadyl/nucleoside complexation and suggested that guanosine (4.12) formed the most stable complex with oxovanadium ions. We were also able to establish a third protonation constant for the hydroxyl moiety in 4.12 with a logK 8.87 which has not been previously reported. Finally, Chapter 5 revisited the cytoxicity two Algoa Bay ascidians, Clavelina sp. and Atriolum marinense the extracts from which produced promising bioactivity results in previous studies against oesophageal cancer cells. The HP-20 fractionated extracts of Clavelina sp. and Atriolum marinense proved to be similalrly cytotoxic to breast cancer cells. With the exception for the 100% acetone(aq)fractions the NMR data for both species suggested that most active non polar fractions were dominated by what appeared to be structurally unremarkable fatty acid glycerides and as such were not pursued further. Purification of the 100% acetone(aq)fraction of A. marinense resulted in the isolation of a styrene trimer, 5.1, common to both ascidian extracts. The NMR simulation software WIN-DAISY was employed to confirm the structure of 5.1. Attempts to establish if 5.1 was an isolation artefact or a product of marine pollution were inconclusive
- Full Text:
- Date Issued: 2016
The Contribution of fruit from trees to improve household nutritional security in the context of deforestation in Cameroon
- Tata epse Ngome, Precillia Ijang
- Authors: Tata epse Ngome, Precillia Ijang
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/793 , vital:19991
- Description: Cameroon needs healthy citizens to archive emergence by 2035. Malnutrition and undernourishment is the highest burden in the World in recent times and a silent crisis facing most rural communities in forest areas of Cameroon. Its abstruseness makes extremely fragile political, social and economic planning to foster development in such areas. Therefore, it is time we bring appropriate understanding and new strategies on unpacking the complexities of food and nutritional security and define practical solutions to food insecurity. Working in the context of increasing deforestation, this thesis brings evidence on the situation of household food insecurity (FIS) access experience in forest areas which is not reported in current discussions at the national level. It further investigates the knowledge and awareness of households on the availability, accessibility, utilisation, vulnerability and consumption of nutrient rich food items using the example of fruits from trees. Thus, the aim of this research was to investigate strategies for addressing household FIS through increased domestic supply and consumption of fruits from trees in the context of deforestation in Cameroon. Data were collected through four rounds of structured interviews completed between August 2013 and October 2014. Analysis was done using simple citations and ordering, Principal Component Analysis (PCA), Likert scale, χ2-test of association and Cramer's V coefficient to test the strength of the association and means and ANOVA. The HFIAS approach used to determine household FIS. Only 1% of the population were food secure and the moderately deforested zone showed the worst trends in food insecurity. Therefore, the effect of deforestation was nuanced. Diverse fruit trees were registered. Households said they required fruits only 2.4 ± 1.5 times per week. Recently, the intake of 400 g of fruit per person per day for good health was announced as a priority of international recognition. However, households were not aware of the importance and frequency of fruit consumption with less than 50% of households eating fruits daily during the harvesting season. Fruit tree nurseries where scarce and seeds where obtained from local sources. Fruit tree diseases where rampant and up to 50% harvest lost was registered for some fruits species. This study has shown that food availability does not necessarily mean adequate food intake. Three opinions about fruit trees and the prevalence of food insecurity in Cameroon has been raised in this thesis. First, there is ineffectiveness in the eradication of FIS because even in agricultural conducive environments, hunger and food insecurity are still prevalent at high rates. Therefore, effective and efficient targeting of food insecured groups need to be promoted in all clusters of the population. Secondly, the national nutrition program is neglecting sensitisation on food consumption patterns and therefore people are not making use of nutrient rich foods even when this maybe found around their environments - taking the case of fruits from trees. Thus, very few people ate fruits and at irregular frequencies of consumption. Thus, there is need to design special campaign programs to promote the consumption of fruits from trees. Thirdly, the word-of-mouth or neighbour-to-neighbour dissemination approach on fruit trees planting has not been efficient across communities. As such nurseries where scarce and people obtained fruit trees plants from natural regeneration or found them on the field when establishing the field. Therefore, in this research, it is postulated that no matter the nature of efforts and level of intervention, what is certain is that addressing FIS requires effective targeting of the vulnerable population and the implementation of novel and practical approaches on promoting access to and consumption of fruits in the right frequencies. This research further revealed that poor eating habits was a problem and lack of knowledge about the frequency and intake of nutrient rich food was serious. For instance, people were not aware on the recommended frequency of fruit consumption and people ate infested fruit while reserving the healthy ones for sale. This is the trap of the food insecurity problem in some regions – knowledge about foods and ways of food utilisation. This is neither a problem of availability nor accessibility, but rather a problem of lack of knowledge and lack of sensitisation. From FAO reports on the state of food insecurity in the world and other studies of food intake in most developing nation, poor food consumption is a global problem in most poor regions and even in rich areas affected by obesity. Thus, there is a need to establish a high level policy framework maybe in the form of a convention or an intergovernmental panel at the level of the United Nations and/or the African Union on ‘reducing malnutrition in all its forms (rates, drivers and consequences on human health and the environment)’. This structure will promote setting priorities, strategies, monitoring on peoples eating habits, setting nutritional standards, and principles and indicators for observing under nutrition, over nutrition and associated problems within all population strata.
- Full Text:
- Date Issued: 2016
- Authors: Tata epse Ngome, Precillia Ijang
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/793 , vital:19991
- Description: Cameroon needs healthy citizens to archive emergence by 2035. Malnutrition and undernourishment is the highest burden in the World in recent times and a silent crisis facing most rural communities in forest areas of Cameroon. Its abstruseness makes extremely fragile political, social and economic planning to foster development in such areas. Therefore, it is time we bring appropriate understanding and new strategies on unpacking the complexities of food and nutritional security and define practical solutions to food insecurity. Working in the context of increasing deforestation, this thesis brings evidence on the situation of household food insecurity (FIS) access experience in forest areas which is not reported in current discussions at the national level. It further investigates the knowledge and awareness of households on the availability, accessibility, utilisation, vulnerability and consumption of nutrient rich food items using the example of fruits from trees. Thus, the aim of this research was to investigate strategies for addressing household FIS through increased domestic supply and consumption of fruits from trees in the context of deforestation in Cameroon. Data were collected through four rounds of structured interviews completed between August 2013 and October 2014. Analysis was done using simple citations and ordering, Principal Component Analysis (PCA), Likert scale, χ2-test of association and Cramer's V coefficient to test the strength of the association and means and ANOVA. The HFIAS approach used to determine household FIS. Only 1% of the population were food secure and the moderately deforested zone showed the worst trends in food insecurity. Therefore, the effect of deforestation was nuanced. Diverse fruit trees were registered. Households said they required fruits only 2.4 ± 1.5 times per week. Recently, the intake of 400 g of fruit per person per day for good health was announced as a priority of international recognition. However, households were not aware of the importance and frequency of fruit consumption with less than 50% of households eating fruits daily during the harvesting season. Fruit tree nurseries where scarce and seeds where obtained from local sources. Fruit tree diseases where rampant and up to 50% harvest lost was registered for some fruits species. This study has shown that food availability does not necessarily mean adequate food intake. Three opinions about fruit trees and the prevalence of food insecurity in Cameroon has been raised in this thesis. First, there is ineffectiveness in the eradication of FIS because even in agricultural conducive environments, hunger and food insecurity are still prevalent at high rates. Therefore, effective and efficient targeting of food insecured groups need to be promoted in all clusters of the population. Secondly, the national nutrition program is neglecting sensitisation on food consumption patterns and therefore people are not making use of nutrient rich foods even when this maybe found around their environments - taking the case of fruits from trees. Thus, very few people ate fruits and at irregular frequencies of consumption. Thus, there is need to design special campaign programs to promote the consumption of fruits from trees. Thirdly, the word-of-mouth or neighbour-to-neighbour dissemination approach on fruit trees planting has not been efficient across communities. As such nurseries where scarce and people obtained fruit trees plants from natural regeneration or found them on the field when establishing the field. Therefore, in this research, it is postulated that no matter the nature of efforts and level of intervention, what is certain is that addressing FIS requires effective targeting of the vulnerable population and the implementation of novel and practical approaches on promoting access to and consumption of fruits in the right frequencies. This research further revealed that poor eating habits was a problem and lack of knowledge about the frequency and intake of nutrient rich food was serious. For instance, people were not aware on the recommended frequency of fruit consumption and people ate infested fruit while reserving the healthy ones for sale. This is the trap of the food insecurity problem in some regions – knowledge about foods and ways of food utilisation. This is neither a problem of availability nor accessibility, but rather a problem of lack of knowledge and lack of sensitisation. From FAO reports on the state of food insecurity in the world and other studies of food intake in most developing nation, poor food consumption is a global problem in most poor regions and even in rich areas affected by obesity. Thus, there is a need to establish a high level policy framework maybe in the form of a convention or an intergovernmental panel at the level of the United Nations and/or the African Union on ‘reducing malnutrition in all its forms (rates, drivers and consequences on human health and the environment)’. This structure will promote setting priorities, strategies, monitoring on peoples eating habits, setting nutritional standards, and principles and indicators for observing under nutrition, over nutrition and associated problems within all population strata.
- Full Text:
- Date Issued: 2016
The development of a discovery and control environment for networked audio devices based on a study of current audio control protocols
- Authors: Eales, Andrew Arnold
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/539 , vital:19968
- Description: This dissertation develops a standard device model for networked audio devices and introduces a novel discovery and control environment that uses the developed device model. The proposed standard device model is derived from a study of current audio control protocols. Both the functional capabilities and design principles of audio control protocols are investigated with an emphasis on Open Sound Control, SNMP and IEC-62379, AES64, CopperLan and UPnP. An abstract model of networked audio devices is developed, and the model is implemented in each of the previously mentioned control protocols. This model is also used within a novel discovery and control environment designed around a distributed associative memory termed an object space. This environment challenges the accepted notions of the functionality provided by a control protocol. The study concludes by comparing the salient features of the different control protocols encountered in this study. Different approaches to control protocol design are considered, and several design heuristics for control protocols are proposed.
- Full Text:
- Date Issued: 2016
- Authors: Eales, Andrew Arnold
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/539 , vital:19968
- Description: This dissertation develops a standard device model for networked audio devices and introduces a novel discovery and control environment that uses the developed device model. The proposed standard device model is derived from a study of current audio control protocols. Both the functional capabilities and design principles of audio control protocols are investigated with an emphasis on Open Sound Control, SNMP and IEC-62379, AES64, CopperLan and UPnP. An abstract model of networked audio devices is developed, and the model is implemented in each of the previously mentioned control protocols. This model is also used within a novel discovery and control environment designed around a distributed associative memory termed an object space. This environment challenges the accepted notions of the functionality provided by a control protocol. The study concludes by comparing the salient features of the different control protocols encountered in this study. Different approaches to control protocol design are considered, and several design heuristics for control protocols are proposed.
- Full Text:
- Date Issued: 2016
The development of trilingual literacy in primary schools in Kenya
- Authors: Mose, Peter N
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/815 , vital:19993
- Description: The Kenyan language in education policy contemplates development of trilingual literacy skills in pupils by the end of standard three. The purpose of this study was to determine to what extent standard three pupils were literate in their mother tongue (Ekegusii), Kiswahili, and English. The study was undertaken in the context of; a language in education policy that provides for the use of mother tongues and Kiswahili (as languages of instruction) in rural and urban schools respectively up to the end of standard three, followed by a transition to an English medium from standard four; a general negative public attitude towards mother tongue instruction; and substantial empirical evidence in support of mother tongue instruction in basic education. Cummins’ Linguistic Interdependence and Linguistic Threshold Hypotheses guided the study. Adopting a mixed methods approach, the study used direct classroom observations, face-to-face interviews, document analyses, and reading tests to obtain data. Thematic, content, and statistical approaches were used in data analysis. It was found that various stakeholders understand key aspects of the language in education policy differently. Secondly, efforts in mother tongue instruction in schools are not motivated by theoretical and empirical foundations; development efforts are hence ineffective and inadequate leaving majority of learners with below average literacy skills in their mother tongue by the end of standard three. Thirdly, teachers do not implement the language in education policy as spelt out in the relevant documents; the three languages have therefore been allocated various classroom functions. Fourthly, the factors that motivate the disregard of the language policy include the language of examinations and textbooks, and transition to standard four in which English is the language of instruction. Lastly, reading scores indicate that majority of pupils transiting to standard four do not possess adequate reading skills to enable them read to learn in a mother tongue, Kiswahili, and English. This is observed across rural, peri-urban, and urban schools. The study recommends that: The ministry of education conducts workshops to re-educate the relevant stakeholders on the meaning and significance of the language in education policy and the significance of mother tongue instruction in second language, literacy, and skill development. This should be followed by a re-classification of primary schools on the basis of linguistic homogeneity, or otherwise, to ensure the intention of the policy is achieved. This could include empowering individual schools to determine language of instruction in lower primary based on language predominance. Secondly, the ministry should provide relevant resources for mother tongues and Kiswahili to develop them as effective languages of instruction as recommended by various past education commission reports. Additionally, a bilingual course in teacher training colleges to equip primary school teachers for bilingualism and biliteracy development should be introduced; one implication of this is teachers giving notes and tests in the languages spelt out in the policy. Thirdly, the ministry should intensify inspection of schools to assess implementation of the policy. Fourthly, future studies should assess mother tongue literacies as well, since they determine the extent and success of second language acquisition and learning; and measures should be put to ensure English is adequately resourced and taught well. Finally, mother tongue instruction should be extended up to, at least, standard five.
- Full Text:
- Date Issued: 2016
- Authors: Mose, Peter N
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/815 , vital:19993
- Description: The Kenyan language in education policy contemplates development of trilingual literacy skills in pupils by the end of standard three. The purpose of this study was to determine to what extent standard three pupils were literate in their mother tongue (Ekegusii), Kiswahili, and English. The study was undertaken in the context of; a language in education policy that provides for the use of mother tongues and Kiswahili (as languages of instruction) in rural and urban schools respectively up to the end of standard three, followed by a transition to an English medium from standard four; a general negative public attitude towards mother tongue instruction; and substantial empirical evidence in support of mother tongue instruction in basic education. Cummins’ Linguistic Interdependence and Linguistic Threshold Hypotheses guided the study. Adopting a mixed methods approach, the study used direct classroom observations, face-to-face interviews, document analyses, and reading tests to obtain data. Thematic, content, and statistical approaches were used in data analysis. It was found that various stakeholders understand key aspects of the language in education policy differently. Secondly, efforts in mother tongue instruction in schools are not motivated by theoretical and empirical foundations; development efforts are hence ineffective and inadequate leaving majority of learners with below average literacy skills in their mother tongue by the end of standard three. Thirdly, teachers do not implement the language in education policy as spelt out in the relevant documents; the three languages have therefore been allocated various classroom functions. Fourthly, the factors that motivate the disregard of the language policy include the language of examinations and textbooks, and transition to standard four in which English is the language of instruction. Lastly, reading scores indicate that majority of pupils transiting to standard four do not possess adequate reading skills to enable them read to learn in a mother tongue, Kiswahili, and English. This is observed across rural, peri-urban, and urban schools. The study recommends that: The ministry of education conducts workshops to re-educate the relevant stakeholders on the meaning and significance of the language in education policy and the significance of mother tongue instruction in second language, literacy, and skill development. This should be followed by a re-classification of primary schools on the basis of linguistic homogeneity, or otherwise, to ensure the intention of the policy is achieved. This could include empowering individual schools to determine language of instruction in lower primary based on language predominance. Secondly, the ministry should provide relevant resources for mother tongues and Kiswahili to develop them as effective languages of instruction as recommended by various past education commission reports. Additionally, a bilingual course in teacher training colleges to equip primary school teachers for bilingualism and biliteracy development should be introduced; one implication of this is teachers giving notes and tests in the languages spelt out in the policy. Thirdly, the ministry should intensify inspection of schools to assess implementation of the policy. Fourthly, future studies should assess mother tongue literacies as well, since they determine the extent and success of second language acquisition and learning; and measures should be put to ensure English is adequately resourced and taught well. Finally, mother tongue instruction should be extended up to, at least, standard five.
- Full Text:
- Date Issued: 2016
The effect of kelp supplementation in formulated feed on the production performance and gut microbiota of South African abalone (Haliotis midae)
- Authors: Nel, Aldi
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/899 , vital:20001
- Description: Formulated feeds with a relatively low (< 5 % of dry mass) kelp (Ecklonia maxima) inclusion level are widely used on commercial abalone (Haliotis midae) farms in South Africa. Although the use of kelp, a major constituent of the natural diet of H. midae, as a dietary supplement is considered to enhance abalone growth and feed utilisation, there are no published studies which quantify the effects of kelp inclusion in formulated feeds. Furthermore, the physiological mechanisms by which kelp supplementation may positively influence abalone digestive physiology and growth are largely unknown. As the kelp supplement is comprised mostly of soluble fibres and abalone gut bacteria associated with macroalgae (and its fibrous polysaccharides) are known to play a key role in digestion, it was hypothesised that the kelp supplement influences the gut-bacterial community profiles of cultured abalone through prebiotic and other metabolic effects. The present thesis thus examined the effect of kelp supplementation on the performance of abalone (Haliotis midae) fed formulated feeds and explored the influence of a kelp supplement on the abalone gut microbiota and its function in the gastrointestinal tract. The key hypotheses of the study were that kelp supplementation in formulated feed: 1) enhances abalone growth; 2) causes a shift in abalone gut-bacterial community composition through a prebiotic-like effect; 3) may induce changes in crop morphology as a result of potential bacterial-associated increases in volatile short-chain fatty acids, and 4) alters digestive enzyme activities in the abalone gut through changes in bacterial-derived (exogenous) digestive enzymes. The growth-promoting efficacy of low-level kelp supplementation was tested by feeding isonitrogenous and isoenergetic experimental feeds containing 0.00 – 3.54 % kelp (dry mass) to sub-adult abalone (~43 mm shell length) for eight months under commercial farm conditions. The growth trial established that kelp supplementation (0.44 – 3.54 % of dry mass) promoted faster growth and improved feed conversion and protein efficiency ratios in cultured abalone compared to abalone fed the non-supplemented control diet, while there were no significant differences in growth for abalone fed the different kelp-supplemented diets (0.44, 0.88, 1.76 and 3.54 % of dry mass). Feed conversion and protein efficiency ratios displayed significant correlations with kelp level in the range of 0.00 – 3.54 % dry mass, and it is therefore recommended that kelp be included in the formulated feeds of cultured South African abalone at a rate of up to 3.54 % of dry mass. A kelp-supplemented (0.88 % dry weight inclusion) feed was fed to abalone under farm conditions to compare gut physiological parameters (crop morphology, digestive enzyme activities and the gut microbiota) in abalone against that of abalone fed an isonitrogenous and isoenergetic non-supplemented control feed. To establish if the observed higher abalone growth rates were related to improved gastrointestinal tract epithelium activity and integrity, as reflected by epithelial cell growth in response to potential changes in bacterial-derived short-chain fatty acid production, crop epithelial morphology was compared between abalone fed the kelp-supplemented and control feeds. Kelp supplementation did not induce any observable changes in crop epithelial cell height for farm-reared sub-adult abalone fed the experimental diets on-farm for seven weeks. This was attributed to the similar macronutrient compositions of kelp-supplemented and control diets and/ or the common diet history of experimental abalone from weaning to the initiation of the experiment. Digestive enzyme activity was compared between abalone fed a kelp-supplemented and a control feed during an on-farm feeding trial with sub-adult abalone. Gut samples were collected after seven weeks and colorimetric enzyme assays were performed for the polysaccharide-degrading enzymes amylase, alginate lyase, laminarinase and fucoidanase, and for acid protease, trypsin and chymotrypsin activity. Amylase and alginate lyase activities were relatively high, compared to the other enzymes. Polysaccharidase and acid protease activity levels did not differ significantly between abalone fed kelp-supplemented and control feeds, but a greater variability in enzyme activity levels was observed in abalone fed the control diet. It was hypothesised that this might be due to the kelp supplement promoting a more stable and less opportunistic gut-bacterial community than the control diet. Pooled gut samples of abalone fed the kelp-supplemented diet were used for proteomic analyses to identify the composition of enzyme proteins of both endogenous and exogenous origin in the abalone digestive system. The key polysaccharidases and proteases in the gut samples of kelp-supplemented formulated feed-fed abalone were all of abalone origin, whereas the bacterial enzymes were of the types that form part of intermediate reactions in metabolic pathways. The results suggested that bacterial enzymes play a different role to abalone endogenous enzymes in the digestion of formulated feed. While abalone enzymes appear to be the main degraders of carbohydrate and protein macromolecules, the profile of exogenous enzymes suggests that they perform bioconversions of smaller organic compounds. The profiles of gut-bacterial communities of farm-reared sub-adult abalone fed kelpsupplemented and control feeds on-farm for seven weeks were analysed with metagenomic pyrosequencing and DGGE analyses, using 16S rDNA-targeted amplified DNA. The results indicated a shift in gut-bacterial composition with a higher abundance of Mollicutes in abalone fed kelp-supplemented feed compared to those fed the control feed. DGGE band patterns displayed a greater within-group similarity in gut bacteria for abalone fed the kelpsupplemented diet and the presence of unique and variable bands for bacteria in the guts of abalone fed the control diet. It was concluded that when cultured abalone are fed kelpsupplemented formulated feeds, more stable gut bacterial communities are present compared to a more opportunistic gut-bacterial community in abalone fed non-supplemented feeds, and that the observed increase in Mollicutes could reflect the restoration of the abalone gut microbiota to a more natural state. The novel application of proteomics to abalone nutrition in the present study demonstrated that gut-bacterial enzymes may form part of many different metabolic pathways and suggests that the metabolism of the gut microbiota serves as an extension of the abalone’s digestive metabolism. Future studies should quantify the contribution of commensal gut-bacteria to cultured abalone nutrition by employing metabolomic studies to characterize the utilisation of bacterial-derived metabolites by the abalone host.
- Full Text:
- Date Issued: 2016
- Authors: Nel, Aldi
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/899 , vital:20001
- Description: Formulated feeds with a relatively low (< 5 % of dry mass) kelp (Ecklonia maxima) inclusion level are widely used on commercial abalone (Haliotis midae) farms in South Africa. Although the use of kelp, a major constituent of the natural diet of H. midae, as a dietary supplement is considered to enhance abalone growth and feed utilisation, there are no published studies which quantify the effects of kelp inclusion in formulated feeds. Furthermore, the physiological mechanisms by which kelp supplementation may positively influence abalone digestive physiology and growth are largely unknown. As the kelp supplement is comprised mostly of soluble fibres and abalone gut bacteria associated with macroalgae (and its fibrous polysaccharides) are known to play a key role in digestion, it was hypothesised that the kelp supplement influences the gut-bacterial community profiles of cultured abalone through prebiotic and other metabolic effects. The present thesis thus examined the effect of kelp supplementation on the performance of abalone (Haliotis midae) fed formulated feeds and explored the influence of a kelp supplement on the abalone gut microbiota and its function in the gastrointestinal tract. The key hypotheses of the study were that kelp supplementation in formulated feed: 1) enhances abalone growth; 2) causes a shift in abalone gut-bacterial community composition through a prebiotic-like effect; 3) may induce changes in crop morphology as a result of potential bacterial-associated increases in volatile short-chain fatty acids, and 4) alters digestive enzyme activities in the abalone gut through changes in bacterial-derived (exogenous) digestive enzymes. The growth-promoting efficacy of low-level kelp supplementation was tested by feeding isonitrogenous and isoenergetic experimental feeds containing 0.00 – 3.54 % kelp (dry mass) to sub-adult abalone (~43 mm shell length) for eight months under commercial farm conditions. The growth trial established that kelp supplementation (0.44 – 3.54 % of dry mass) promoted faster growth and improved feed conversion and protein efficiency ratios in cultured abalone compared to abalone fed the non-supplemented control diet, while there were no significant differences in growth for abalone fed the different kelp-supplemented diets (0.44, 0.88, 1.76 and 3.54 % of dry mass). Feed conversion and protein efficiency ratios displayed significant correlations with kelp level in the range of 0.00 – 3.54 % dry mass, and it is therefore recommended that kelp be included in the formulated feeds of cultured South African abalone at a rate of up to 3.54 % of dry mass. A kelp-supplemented (0.88 % dry weight inclusion) feed was fed to abalone under farm conditions to compare gut physiological parameters (crop morphology, digestive enzyme activities and the gut microbiota) in abalone against that of abalone fed an isonitrogenous and isoenergetic non-supplemented control feed. To establish if the observed higher abalone growth rates were related to improved gastrointestinal tract epithelium activity and integrity, as reflected by epithelial cell growth in response to potential changes in bacterial-derived short-chain fatty acid production, crop epithelial morphology was compared between abalone fed the kelp-supplemented and control feeds. Kelp supplementation did not induce any observable changes in crop epithelial cell height for farm-reared sub-adult abalone fed the experimental diets on-farm for seven weeks. This was attributed to the similar macronutrient compositions of kelp-supplemented and control diets and/ or the common diet history of experimental abalone from weaning to the initiation of the experiment. Digestive enzyme activity was compared between abalone fed a kelp-supplemented and a control feed during an on-farm feeding trial with sub-adult abalone. Gut samples were collected after seven weeks and colorimetric enzyme assays were performed for the polysaccharide-degrading enzymes amylase, alginate lyase, laminarinase and fucoidanase, and for acid protease, trypsin and chymotrypsin activity. Amylase and alginate lyase activities were relatively high, compared to the other enzymes. Polysaccharidase and acid protease activity levels did not differ significantly between abalone fed kelp-supplemented and control feeds, but a greater variability in enzyme activity levels was observed in abalone fed the control diet. It was hypothesised that this might be due to the kelp supplement promoting a more stable and less opportunistic gut-bacterial community than the control diet. Pooled gut samples of abalone fed the kelp-supplemented diet were used for proteomic analyses to identify the composition of enzyme proteins of both endogenous and exogenous origin in the abalone digestive system. The key polysaccharidases and proteases in the gut samples of kelp-supplemented formulated feed-fed abalone were all of abalone origin, whereas the bacterial enzymes were of the types that form part of intermediate reactions in metabolic pathways. The results suggested that bacterial enzymes play a different role to abalone endogenous enzymes in the digestion of formulated feed. While abalone enzymes appear to be the main degraders of carbohydrate and protein macromolecules, the profile of exogenous enzymes suggests that they perform bioconversions of smaller organic compounds. The profiles of gut-bacterial communities of farm-reared sub-adult abalone fed kelpsupplemented and control feeds on-farm for seven weeks were analysed with metagenomic pyrosequencing and DGGE analyses, using 16S rDNA-targeted amplified DNA. The results indicated a shift in gut-bacterial composition with a higher abundance of Mollicutes in abalone fed kelp-supplemented feed compared to those fed the control feed. DGGE band patterns displayed a greater within-group similarity in gut bacteria for abalone fed the kelpsupplemented diet and the presence of unique and variable bands for bacteria in the guts of abalone fed the control diet. It was concluded that when cultured abalone are fed kelpsupplemented formulated feeds, more stable gut bacterial communities are present compared to a more opportunistic gut-bacterial community in abalone fed non-supplemented feeds, and that the observed increase in Mollicutes could reflect the restoration of the abalone gut microbiota to a more natural state. The novel application of proteomics to abalone nutrition in the present study demonstrated that gut-bacterial enzymes may form part of many different metabolic pathways and suggests that the metabolism of the gut microbiota serves as an extension of the abalone’s digestive metabolism. Future studies should quantify the contribution of commensal gut-bacteria to cultured abalone nutrition by employing metabolomic studies to characterize the utilisation of bacterial-derived metabolites by the abalone host.
- Full Text:
- Date Issued: 2016
The effect of shaped nanoparticles on the photophysicochemical behaviour of metallophthalocyanines
- Authors: D'Souza, Sarah
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/529 , vital:19967
- Description: The synthesis, spectroscopic characterization and photophysicochemical analysis of novel and known metallophthalocyanines are reported in this thesis. The novel lowsymmetry compounds were extensively studied. Selected phthalocyanines were conjugated to a variety of nanoparticles consisting of silver (AgNPs), gold (AuNPs) and zinc oxide (ZnO NPs) in order to improve their photophysical and photochemical behaviour. As with the phthalocyanines, the nanoparticles and phthalocyaninenanoparticle conjugates were thoroughly investigated. Research on the effect of the solvent used, as well as the influence of nanoparticle composition and shape on the properties of the phthalocyanines, were performed. The findings showed that there was a general increase in triplet quantum yields of the phthalocyanines in the presence of the nanoparticles. It was also noted that the use of different solvents directly affected the photophysicochemical properties. In the case of the nanoparticle conjugates, photophysical and photochemical changes were observed. Of significance were the gold nanostars, which decreased the degree of phthalocyanine aggregation in water, resulting in increased fluorescence lifetimes. The studies also revealed that the effect of the nanoparticle shape on the phthalocyanine properties was highly dependent on the nanoparticle material. The photodynamic antimicrobial activity of selected phthalocyanine-zinc oxide nanoparticle conjugates was investigated against Staphylococcus aureus (S. aureus) in solution. The phthalocyanines alone exhibited remarkable growth inhibition, however the presence of the nanoparticles in the conjugates increased the photoinactivation of S. aureus.
- Full Text:
- Date Issued: 2016
- Authors: D'Souza, Sarah
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/529 , vital:19967
- Description: The synthesis, spectroscopic characterization and photophysicochemical analysis of novel and known metallophthalocyanines are reported in this thesis. The novel lowsymmetry compounds were extensively studied. Selected phthalocyanines were conjugated to a variety of nanoparticles consisting of silver (AgNPs), gold (AuNPs) and zinc oxide (ZnO NPs) in order to improve their photophysical and photochemical behaviour. As with the phthalocyanines, the nanoparticles and phthalocyaninenanoparticle conjugates were thoroughly investigated. Research on the effect of the solvent used, as well as the influence of nanoparticle composition and shape on the properties of the phthalocyanines, were performed. The findings showed that there was a general increase in triplet quantum yields of the phthalocyanines in the presence of the nanoparticles. It was also noted that the use of different solvents directly affected the photophysicochemical properties. In the case of the nanoparticle conjugates, photophysical and photochemical changes were observed. Of significance were the gold nanostars, which decreased the degree of phthalocyanine aggregation in water, resulting in increased fluorescence lifetimes. The studies also revealed that the effect of the nanoparticle shape on the phthalocyanine properties was highly dependent on the nanoparticle material. The photodynamic antimicrobial activity of selected phthalocyanine-zinc oxide nanoparticle conjugates was investigated against Staphylococcus aureus (S. aureus) in solution. The phthalocyanines alone exhibited remarkable growth inhibition, however the presence of the nanoparticles in the conjugates increased the photoinactivation of S. aureus.
- Full Text:
- Date Issued: 2016
The effects of a gradual shift rotation and a split shift nap intervention on cognitive, physiological and subjective responses under simulated night shift settings
- Authors: Davy, Jonathan Patrick
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/517 , vital:19966
- Description: Introduction: Shift work, particularly work that occurs at night has been associated with numerous challenges to occupational safety and productivity. This stems from the associated extended wakefulness, circadian disruptions and sleep loss from the inversion of the sleep wake cycle, which predisposes shift workers to reduced alertness, increased fatigue and decrements in performance capacity. These effects may be exacerbated over consecutive night shifts as a result of reductions in sleep length associated with attempting to sleep against the alerting signals of the circadian rhythm during the day. Although a variety of shift work countermeasures exist, new and innovative fatigue management strategies are needed to mitigate the effects of night work. This study proposed two night shift interventions; the Rolling rotation and a split shift nap combination. Aims: The aim of this study was to explore the effects of these interventions to a conventional Fixed night shift arrangement. Selected performance, physiological and subjective measures were applied to track any effects during a five-day shift work study. Methods: The study was laboratory-based and performance was quantified through the application of computer-based perceptual, cognitive and motor tests. Student participants (24 females and 21 males) partook in the study, which adopted a nonrepeated measures design and spanned five consecutive days. During this time, participants were required to perform a simple beading task over five 8-hour shifts. Participants were split according to sex and chronotype between four independent conditions; 1. Fixed night condition required participants to complete one afternoon shift (14h00 – 22h00) and four consecutive night shifts (22h00 - 06h00) 2. Rolling rotation condition gradually “rolled” participants into the night shift by delaying the start and end of an afternoon shift by two hours each day (16h00 – 00h00, 18h00 – 02h00, 20h00 – 04h00, 22h00 – 06h00) until the times matched that of the Fixed night condition. 3. The split shift nap system was made up of two independent groups, both of which completed one afternoon (14h00 to 22h00) and four night shifts. The Nap early condition worked from 20h00 to 08h00, napping between 00h00 and 04h00, while the Nap late condition worked from 00h00 to 12h00 and napped between 04h00 and 08h00 during the night shifts. Napping, the opportunity for which was 200 minutes occurred in the laboratory, but post shift recovery sleep, for all conditions, happened outside the laboratory. During each shift, six test batteries were completed, in which the following measures were taken: 1. Performance: beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. 2. Physiological: heart rate, heart rate variability (r-MSSD, normalised Low frequency power: LFnu). 3. Self-reported measures: subjective sleepiness and reported sleep length and quality while outside the laboratory. Results: Analyses revealed that: 1. Measures of beading performance, simple reaction time, vigilance and object recognition, working memory, motor response time and control, all physiological measures, except LFnu and subjective sleepiness demonstrated the effects of time of day / fatigue, irrespective of condition. 2. There was no evidence of cumulative fatigue over the four night shifts in the performance and subjective measures and most of the physiological indicators. Beading output decreased significantly over the course of the night shifts, while reported post shift sleep length was significantly reduced with the start of the night shifts, irrespective of condition. 3. The majority of the physiological and performance measures did not differ significantly between conditions. However, there were some effects: the Rolling rotation condition produced the highest beading output compared to the Nap late condition; working memory was significantly lower in the Nap late condition compared to the other conditions. Furthermore, the nap opportunity in both the Nap early and Nap late conditions reduced subjective sleepiness, while napping during the night shift reduced post shift sleep length compared to the Rolling rotation and Fixed night conditions. There was also evidence of sleep inertia following pre-post nap test comparisons, which mainly affected visual perception tasks in both nap conditions. Sleep inertia possibly also accounted for an apparent dissociation between subjective and performance measures. Conclusions: Quantifying and interpreting the effects of night shift work in a laboratory setting has limitations. These stem mainly from the limited ecological validity of the performance outcome measures adopted and the characteristics of the sample that is tested. However, in order to fully understand the efficacy of any shift work countermeasure, the laboratory setting offers a safe, controlled environment in which to do so. The conclusions should thus be considered in light of these limitations. Night shift work negatively affected all elements of human information processing. The combination of reduced physiological arousal, extended wakefulness, increased perceptions of sleepiness and reduced total sleep obtained explained these decrements in performance. While cumulative fatigue has been reported as a challenge associated with night shift work, there was no conclusive evidence of this in the current study. In the case of the Rolling rotation, the gradual introduction to the night shift delayed the inevitable reduction in alertness and performance, which limits the viability of this intervention. The inclusion of the nap interventions was associated with reduced perceptions of sleepiness, which did not translate into improved performance, relative to the Rolling rotation and Fixed night conditions. Apart from considerations of how to manage sleep inertia post nap, the split shift nap intervention can provide an alternative to conventional night shift work arrangements.
- Full Text:
- Date Issued: 2016
- Authors: Davy, Jonathan Patrick
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/517 , vital:19966
- Description: Introduction: Shift work, particularly work that occurs at night has been associated with numerous challenges to occupational safety and productivity. This stems from the associated extended wakefulness, circadian disruptions and sleep loss from the inversion of the sleep wake cycle, which predisposes shift workers to reduced alertness, increased fatigue and decrements in performance capacity. These effects may be exacerbated over consecutive night shifts as a result of reductions in sleep length associated with attempting to sleep against the alerting signals of the circadian rhythm during the day. Although a variety of shift work countermeasures exist, new and innovative fatigue management strategies are needed to mitigate the effects of night work. This study proposed two night shift interventions; the Rolling rotation and a split shift nap combination. Aims: The aim of this study was to explore the effects of these interventions to a conventional Fixed night shift arrangement. Selected performance, physiological and subjective measures were applied to track any effects during a five-day shift work study. Methods: The study was laboratory-based and performance was quantified through the application of computer-based perceptual, cognitive and motor tests. Student participants (24 females and 21 males) partook in the study, which adopted a nonrepeated measures design and spanned five consecutive days. During this time, participants were required to perform a simple beading task over five 8-hour shifts. Participants were split according to sex and chronotype between four independent conditions; 1. Fixed night condition required participants to complete one afternoon shift (14h00 – 22h00) and four consecutive night shifts (22h00 - 06h00) 2. Rolling rotation condition gradually “rolled” participants into the night shift by delaying the start and end of an afternoon shift by two hours each day (16h00 – 00h00, 18h00 – 02h00, 20h00 – 04h00, 22h00 – 06h00) until the times matched that of the Fixed night condition. 3. The split shift nap system was made up of two independent groups, both of which completed one afternoon (14h00 to 22h00) and four night shifts. The Nap early condition worked from 20h00 to 08h00, napping between 00h00 and 04h00, while the Nap late condition worked from 00h00 to 12h00 and napped between 04h00 and 08h00 during the night shifts. Napping, the opportunity for which was 200 minutes occurred in the laboratory, but post shift recovery sleep, for all conditions, happened outside the laboratory. During each shift, six test batteries were completed, in which the following measures were taken: 1. Performance: beading output, eye accommodation time, choice reaction time, visual vigilance, simple reaction time, processing speed and object recognition, working memory, motor response time and tracking performance. 2. Physiological: heart rate, heart rate variability (r-MSSD, normalised Low frequency power: LFnu). 3. Self-reported measures: subjective sleepiness and reported sleep length and quality while outside the laboratory. Results: Analyses revealed that: 1. Measures of beading performance, simple reaction time, vigilance and object recognition, working memory, motor response time and control, all physiological measures, except LFnu and subjective sleepiness demonstrated the effects of time of day / fatigue, irrespective of condition. 2. There was no evidence of cumulative fatigue over the four night shifts in the performance and subjective measures and most of the physiological indicators. Beading output decreased significantly over the course of the night shifts, while reported post shift sleep length was significantly reduced with the start of the night shifts, irrespective of condition. 3. The majority of the physiological and performance measures did not differ significantly between conditions. However, there were some effects: the Rolling rotation condition produced the highest beading output compared to the Nap late condition; working memory was significantly lower in the Nap late condition compared to the other conditions. Furthermore, the nap opportunity in both the Nap early and Nap late conditions reduced subjective sleepiness, while napping during the night shift reduced post shift sleep length compared to the Rolling rotation and Fixed night conditions. There was also evidence of sleep inertia following pre-post nap test comparisons, which mainly affected visual perception tasks in both nap conditions. Sleep inertia possibly also accounted for an apparent dissociation between subjective and performance measures. Conclusions: Quantifying and interpreting the effects of night shift work in a laboratory setting has limitations. These stem mainly from the limited ecological validity of the performance outcome measures adopted and the characteristics of the sample that is tested. However, in order to fully understand the efficacy of any shift work countermeasure, the laboratory setting offers a safe, controlled environment in which to do so. The conclusions should thus be considered in light of these limitations. Night shift work negatively affected all elements of human information processing. The combination of reduced physiological arousal, extended wakefulness, increased perceptions of sleepiness and reduced total sleep obtained explained these decrements in performance. While cumulative fatigue has been reported as a challenge associated with night shift work, there was no conclusive evidence of this in the current study. In the case of the Rolling rotation, the gradual introduction to the night shift delayed the inevitable reduction in alertness and performance, which limits the viability of this intervention. The inclusion of the nap interventions was associated with reduced perceptions of sleepiness, which did not translate into improved performance, relative to the Rolling rotation and Fixed night conditions. Apart from considerations of how to manage sleep inertia post nap, the split shift nap intervention can provide an alternative to conventional night shift work arrangements.
- Full Text:
- Date Issued: 2016
The effects of land use on the avifauna and its conservation in a Kenyan coastal forest ecosystem, and the significance of the Arabuko Sokoke Forest to the local community
- Authors: Chiawo, David O
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5950 , http://hdl.handle.net/10962/d1020946
- Description: This study examines the effects of land use on the bird community of Arabuko Sokoke Forest, the largest area of coastal forest remaining in East Africa and a major Important Bird Area in mainland Kenya. Bird species diversity in three land use types (primary forest, plantation and farm lands) was compared using multivariate analysis to determine the response of different feeding guilds to habitat characteristics. The effect of habitat characteristics on overall bird diversity and specific feeding guilds was tested using linear mixed models. A total of 2600 bird observations were recorded during point counts, representing 97 bird species including 25 fruit-eating birds, 17 nectar feeders; and 60 species belonging exclusively to other feeding guilds. Land use had a significant effect on overall bird diversity and abundance. The distribution of frugivorous birds was primarily influenced by the presence of fruiting trees rather than land use type, while nectarivores were significantly affected by vertical habitat heterogeneity and vegetation type. Although the distribution of insectivorous birds is influenced by many habitat factors, proximity to natural forest, habitat heterogeneity, and the presence of large trees and fruiting trees appear to be most important to this guild. The natural forest has the greatest avian diversity and a distinctive community compared to plantation and farmlands. Patterns of habitat use by birds in the area suggest that vertical vegetation heterogeneity and complexity is especially significant in sustaining diverse and abundant bird populations, if they are in close proximity to native forests. Improvement of conservation management for the plantation and farmlands is thus critical for connectivity with other remnant primary forest patches in the area. Socio-economic data was collected from 109 forest adjacent households to determine the value of the forest to the local community and their perception of conservation issues. Arabuko Sokoke Forest is important in supplementing the livelihood needs of the local community. However, the community lacks information on the forest management plan and many people have little knowledge of local birds, which could limit their capacity to participate in conservation projects. Drivers for local community participation in conservation projects are primarily a sustainable income and the fulfillment of basic household needs. Community conservation education is needed to promote local knowledge of forest biodiversity, as well as clear frameworks for the active involvement of the local community in forest management. Support of community based projects is vital to achieve both the conservation and livelihood objectives of the Arabuko Sokoke Forest management plan.
- Full Text:
- Date Issued: 2016
- Authors: Chiawo, David O
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5950 , http://hdl.handle.net/10962/d1020946
- Description: This study examines the effects of land use on the bird community of Arabuko Sokoke Forest, the largest area of coastal forest remaining in East Africa and a major Important Bird Area in mainland Kenya. Bird species diversity in three land use types (primary forest, plantation and farm lands) was compared using multivariate analysis to determine the response of different feeding guilds to habitat characteristics. The effect of habitat characteristics on overall bird diversity and specific feeding guilds was tested using linear mixed models. A total of 2600 bird observations were recorded during point counts, representing 97 bird species including 25 fruit-eating birds, 17 nectar feeders; and 60 species belonging exclusively to other feeding guilds. Land use had a significant effect on overall bird diversity and abundance. The distribution of frugivorous birds was primarily influenced by the presence of fruiting trees rather than land use type, while nectarivores were significantly affected by vertical habitat heterogeneity and vegetation type. Although the distribution of insectivorous birds is influenced by many habitat factors, proximity to natural forest, habitat heterogeneity, and the presence of large trees and fruiting trees appear to be most important to this guild. The natural forest has the greatest avian diversity and a distinctive community compared to plantation and farmlands. Patterns of habitat use by birds in the area suggest that vertical vegetation heterogeneity and complexity is especially significant in sustaining diverse and abundant bird populations, if they are in close proximity to native forests. Improvement of conservation management for the plantation and farmlands is thus critical for connectivity with other remnant primary forest patches in the area. Socio-economic data was collected from 109 forest adjacent households to determine the value of the forest to the local community and their perception of conservation issues. Arabuko Sokoke Forest is important in supplementing the livelihood needs of the local community. However, the community lacks information on the forest management plan and many people have little knowledge of local birds, which could limit their capacity to participate in conservation projects. Drivers for local community participation in conservation projects are primarily a sustainable income and the fulfillment of basic household needs. Community conservation education is needed to promote local knowledge of forest biodiversity, as well as clear frameworks for the active involvement of the local community in forest management. Support of community based projects is vital to achieve both the conservation and livelihood objectives of the Arabuko Sokoke Forest management plan.
- Full Text:
- Date Issued: 2016
The gendered appropriation of the mobile phone for online health information by youths in Zimbabwean tertiary learning institutions
- Authors: Tsarwe, Stanley Zvinaiye
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/738 , vital:19986
- Description: The study uses domestication of technology and Cultural Studies theories to investigate how youth in three institutions of tertiary learning in Harare, Zimbabwe are accessing health-related information online using their smart phones. The study critically examines how youths deploy these digital media technologies to construct their identities in a context where social and political power is unevenly distributed. To understand these issues, the study uses a triangulated research design comprising a social survey, in-depth individual interviews and field observation for data collection. Results from this data gathering showed that the use of digital media technologies differ across gender, at least in terms of the distribution of online health seeking practices between male and female youths. According to the survey results, more women tend to use their mobile phones to access health-related information. Data from the individual in-depth interviews showed that the most significant site of social change (social disruption) relates to how digital media facilitates emerging new identities (i.e. identity in the broader sense as well as health-related and sexual health identities). For both young men and young women, mobile phones are used precisely for image management, peer acceptance and the desire to define respective feminities and masculinities within their social networks. Both male and female youths assert they are able to access a variety of information online, and some of this information would not easily accessible when sought from traditional structures such as their parents. This way, youth feel that digital media technologies allow them to cultivate their own preferred identities outside the purview of parental authority and social control. Drawing on postmodern literature, such emerging identities are predicated on cultural volatility, unpredictability, decentralisation and refusal to fixation and conformity to socially constructed identities about being a youth, or being a young Zimbabwean woman or man, for example. Thus, the use of mobile phones and mobile Internet by youths in Zimbabwe to access health-related information has sociopolitical significance, because it allows young people to fashion preferred identities that resists entrenched regimes of social power. For young people in Zimbabwe, online health seeking practices precisely reflects attempt towards negotiating with and circumvent the structural limitations of either an expensive health care system or the general curiosity associated with growing up. That way, it is arguable that youth use digital media technologies to help them exercise some level of social autonomy and agency in dealing with everyday life. Individual in-depth interviews demonstrated that mobile phones and mobile Internet can thus be seen as opening up more spaces for youth to learn more about issues about growing up, sexuality and adolescents that a conservative society such as Zimbabwe traditionally consider as ‘inappropriate’ for youth consumption. They argued that the inability of parents to discuss with them issues about growing up often result in them “finding out on our own” using digital media technologies to satisfy the desire to wean themselves from what they view as arbitrary and asymmetrical social power. The study demonstrated that youth use the mobile phone to challenge the social world of adults and to show resistance to it, thereby strengthening a subculture as well as constructing an identity. However, despite the positive attributes of social capital, connectivity and personalised experience afforded by the mobile phone, the mobile phone is sometimes a source of conflict in relationships between young men and women; that is, between unmarried partners. Young women reported that their boyfriends often force them to disclose who they communicate with using their mobile phones. They also reported that their boyfriends often did some random surveillance of their social media contacts and activities. Thus, whilst one of the mobile phone’s most powerful attribute is its ability to offer personalised experience, as well as offer synchronised and unlimited access to distant connections, results from in-depth interviews showed that some unwritten expectations and norms dictated that young men closely watch their ‘girlfriends’ social media activities, including their online search activities. As a result, privacy as well as the much touted relationship between mobile phone and women’s autonomy becomes contested arenas. Even at young ages, and before marriage, women are socialised to show subservience to their partners by allowing them access to their mobile phones.
- Full Text:
- Date Issued: 2016
- Authors: Tsarwe, Stanley Zvinaiye
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/738 , vital:19986
- Description: The study uses domestication of technology and Cultural Studies theories to investigate how youth in three institutions of tertiary learning in Harare, Zimbabwe are accessing health-related information online using their smart phones. The study critically examines how youths deploy these digital media technologies to construct their identities in a context where social and political power is unevenly distributed. To understand these issues, the study uses a triangulated research design comprising a social survey, in-depth individual interviews and field observation for data collection. Results from this data gathering showed that the use of digital media technologies differ across gender, at least in terms of the distribution of online health seeking practices between male and female youths. According to the survey results, more women tend to use their mobile phones to access health-related information. Data from the individual in-depth interviews showed that the most significant site of social change (social disruption) relates to how digital media facilitates emerging new identities (i.e. identity in the broader sense as well as health-related and sexual health identities). For both young men and young women, mobile phones are used precisely for image management, peer acceptance and the desire to define respective feminities and masculinities within their social networks. Both male and female youths assert they are able to access a variety of information online, and some of this information would not easily accessible when sought from traditional structures such as their parents. This way, youth feel that digital media technologies allow them to cultivate their own preferred identities outside the purview of parental authority and social control. Drawing on postmodern literature, such emerging identities are predicated on cultural volatility, unpredictability, decentralisation and refusal to fixation and conformity to socially constructed identities about being a youth, or being a young Zimbabwean woman or man, for example. Thus, the use of mobile phones and mobile Internet by youths in Zimbabwe to access health-related information has sociopolitical significance, because it allows young people to fashion preferred identities that resists entrenched regimes of social power. For young people in Zimbabwe, online health seeking practices precisely reflects attempt towards negotiating with and circumvent the structural limitations of either an expensive health care system or the general curiosity associated with growing up. That way, it is arguable that youth use digital media technologies to help them exercise some level of social autonomy and agency in dealing with everyday life. Individual in-depth interviews demonstrated that mobile phones and mobile Internet can thus be seen as opening up more spaces for youth to learn more about issues about growing up, sexuality and adolescents that a conservative society such as Zimbabwe traditionally consider as ‘inappropriate’ for youth consumption. They argued that the inability of parents to discuss with them issues about growing up often result in them “finding out on our own” using digital media technologies to satisfy the desire to wean themselves from what they view as arbitrary and asymmetrical social power. The study demonstrated that youth use the mobile phone to challenge the social world of adults and to show resistance to it, thereby strengthening a subculture as well as constructing an identity. However, despite the positive attributes of social capital, connectivity and personalised experience afforded by the mobile phone, the mobile phone is sometimes a source of conflict in relationships between young men and women; that is, between unmarried partners. Young women reported that their boyfriends often force them to disclose who they communicate with using their mobile phones. They also reported that their boyfriends often did some random surveillance of their social media contacts and activities. Thus, whilst one of the mobile phone’s most powerful attribute is its ability to offer personalised experience, as well as offer synchronised and unlimited access to distant connections, results from in-depth interviews showed that some unwritten expectations and norms dictated that young men closely watch their ‘girlfriends’ social media activities, including their online search activities. As a result, privacy as well as the much touted relationship between mobile phone and women’s autonomy becomes contested arenas. Even at young ages, and before marriage, women are socialised to show subservience to their partners by allowing them access to their mobile phones.
- Full Text:
- Date Issued: 2016
The influence of introduced forest management practices on transformative social learning in a selected social-ecological forest community : a case of PFM and REDD projects at Pugu and Kazimzumbwi Forest Reserves in Tanzania
- Authors: Ferdinand, Victoria Ugulumu
- Date: 2016
- Subjects: Forest management -- Tanzania , Forest reserves -- Tanzania , Transformative learning , Social ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2064 , http://hdl.handle.net/10962/d1020333
- Description: This research investigates the influence of introduced forest management approaches on transformative social learning in the community surrounding the Pugu and Kazimzumbwi forest reserves in Tanzania from 2000 to 2015. The term transformative social learning reflects an understanding of learning processes that emerge through conscious changes in the perspectives of individuals or communities while interacting with forest management practices. The investigation explores the learning (if any) that occurred in the community and how and why the learning occurred. It also explores whether the learning was social and transformative and examines the conditions that enable or constrain transformative social learning at the Pugu and Kazimzumbwi community. Thus, the three concepts of social learning, transformative learning, and social practices are central to the research. Participatory Forest Management (PFM) emerged globally in the early 1980s to mobilise rural capabilities and resources in development and environmental stewardship. The Pugu and Kazimzumbwi community was introduced to Participatory Forest Management (PFM) projects by the late 1990s. The recent global focus on empowering communities around forests has drawn attention towards transformational adaptation to climate change impacts and building resilience capacities. As a result, in 2011 the Pugu and Kazimzumbwi community started working with a project for Reduction of Emissions through Deforestation and forest Degradation (REDD), which forms a key focus in this study as the most recently introduced PFM with embedded social learning assumptions. This research is designed and conducted as a qualitative case study. The research seeks to study the complex object of socially and contextually constructed learning through a systemic exploration of learning,using semi-structured interviews, focus group discussions, analysis of documents and archival records as well as observations and a reflexive workshop. Supportive information throughfield notes and audio voice and video recording was also generated. A contextual profile of the research site was conducted in March 2012, prior to the actual data collection in 2013 and 2014. Field explorations during the contextual profile helped to describe the research site and promote initial understanding of the context. During data collection, field inquiries based on interactive relationships between a researcher and participants stimulated practice memories and people’s living experiences with forestry and the introduced PFM projects under examination. Analysis of data employed analytical modes of induction, abduction and retroduction. Thick descriptions of learning obtained from fieldi based interactionswere produced before re-contextualising data through theoretical lenses. The research employed realist social theory by Archer (1995), under-laboured by critical realism, and practice theory advanced by Schatzki (2012) and Kemmis et al. (2014). The research process as a whole was underlaboured by the layered ontology of critical realism which proposes emergence of phenomena in open systems as shaped by interacting mechanisms which in this study were both material / ecological and social /political /economic /cultural. And more...
- Full Text:
- Date Issued: 2016
- Authors: Ferdinand, Victoria Ugulumu
- Date: 2016
- Subjects: Forest management -- Tanzania , Forest reserves -- Tanzania , Transformative learning , Social ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2064 , http://hdl.handle.net/10962/d1020333
- Description: This research investigates the influence of introduced forest management approaches on transformative social learning in the community surrounding the Pugu and Kazimzumbwi forest reserves in Tanzania from 2000 to 2015. The term transformative social learning reflects an understanding of learning processes that emerge through conscious changes in the perspectives of individuals or communities while interacting with forest management practices. The investigation explores the learning (if any) that occurred in the community and how and why the learning occurred. It also explores whether the learning was social and transformative and examines the conditions that enable or constrain transformative social learning at the Pugu and Kazimzumbwi community. Thus, the three concepts of social learning, transformative learning, and social practices are central to the research. Participatory Forest Management (PFM) emerged globally in the early 1980s to mobilise rural capabilities and resources in development and environmental stewardship. The Pugu and Kazimzumbwi community was introduced to Participatory Forest Management (PFM) projects by the late 1990s. The recent global focus on empowering communities around forests has drawn attention towards transformational adaptation to climate change impacts and building resilience capacities. As a result, in 2011 the Pugu and Kazimzumbwi community started working with a project for Reduction of Emissions through Deforestation and forest Degradation (REDD), which forms a key focus in this study as the most recently introduced PFM with embedded social learning assumptions. This research is designed and conducted as a qualitative case study. The research seeks to study the complex object of socially and contextually constructed learning through a systemic exploration of learning,using semi-structured interviews, focus group discussions, analysis of documents and archival records as well as observations and a reflexive workshop. Supportive information throughfield notes and audio voice and video recording was also generated. A contextual profile of the research site was conducted in March 2012, prior to the actual data collection in 2013 and 2014. Field explorations during the contextual profile helped to describe the research site and promote initial understanding of the context. During data collection, field inquiries based on interactive relationships between a researcher and participants stimulated practice memories and people’s living experiences with forestry and the introduced PFM projects under examination. Analysis of data employed analytical modes of induction, abduction and retroduction. Thick descriptions of learning obtained from fieldi based interactionswere produced before re-contextualising data through theoretical lenses. The research employed realist social theory by Archer (1995), under-laboured by critical realism, and practice theory advanced by Schatzki (2012) and Kemmis et al. (2014). The research process as a whole was underlaboured by the layered ontology of critical realism which proposes emergence of phenomena in open systems as shaped by interacting mechanisms which in this study were both material / ecological and social /political /economic /cultural. And more...
- Full Text:
- Date Issued: 2016