μCloud : a P2P cloud platform for computing service provision
- Authors: Fouodji Tasse, Ghislain
- Date: 2012 , 2012-08-22
- Subjects: Cloud computing , Peer-to-peer architecture (Computer networks) , Computer architecture , Computer service industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4663 , http://hdl.handle.net/10962/d1006669 , Cloud computing , Peer-to-peer architecture (Computer networks) , Computer architecture , Computer service industry
- Description: The advancements in virtualization technologies have provided a large spectrum of computational approaches. Dedicated computations can be run on private environments (virtual machines), created within the same computer. Through capable APIs, this functionality is leveraged for the service we wish to implement; a computer power service (CPS). We target peer-to-peer systems for this service, to exploit the potential of aggregating computing resources. The concept of a P2P network is mostly known for its expanded usage in distributed networks for sharing resources like content files or real-time data. This study adds computing power to the list of shared resources by describing a suitable service composition. Taking into account the dynamic nature of the platform, this CPS provision is achieved using a self stabilizing clustering algorithm. So, the resulting system of our research is based around a hierarchical P2P architecture and offers end-to-end consideration of resource provisioning and reliability. We named this system μCloud and characterizes it as a self-provisioning cloud service platform. It is designed, implemented and presented in this dissertation. Eventually, we assessed our work by showing that μCloud succeeds in providing user-centric services using a P2P computing unit. With this, we conclude that our system would be highly beneficial in both small and massively deployed environments. , KMBT_223 , Adobe Acrobat 9.51 Paper Capture Plug-in
- Full Text:
- Date Issued: 2012
- Authors: Fouodji Tasse, Ghislain
- Date: 2012 , 2012-08-22
- Subjects: Cloud computing , Peer-to-peer architecture (Computer networks) , Computer architecture , Computer service industry
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4663 , http://hdl.handle.net/10962/d1006669 , Cloud computing , Peer-to-peer architecture (Computer networks) , Computer architecture , Computer service industry
- Description: The advancements in virtualization technologies have provided a large spectrum of computational approaches. Dedicated computations can be run on private environments (virtual machines), created within the same computer. Through capable APIs, this functionality is leveraged for the service we wish to implement; a computer power service (CPS). We target peer-to-peer systems for this service, to exploit the potential of aggregating computing resources. The concept of a P2P network is mostly known for its expanded usage in distributed networks for sharing resources like content files or real-time data. This study adds computing power to the list of shared resources by describing a suitable service composition. Taking into account the dynamic nature of the platform, this CPS provision is achieved using a self stabilizing clustering algorithm. So, the resulting system of our research is based around a hierarchical P2P architecture and offers end-to-end consideration of resource provisioning and reliability. We named this system μCloud and characterizes it as a self-provisioning cloud service platform. It is designed, implemented and presented in this dissertation. Eventually, we assessed our work by showing that μCloud succeeds in providing user-centric services using a P2P computing unit. With this, we conclude that our system would be highly beneficial in both small and massively deployed environments. , KMBT_223 , Adobe Acrobat 9.51 Paper Capture Plug-in
- Full Text:
- Date Issued: 2012
Zoning the Southwestern Indian Ocean to mitigate impacts from ocean-based hydrocarbon exploration and production on sea turtles
- Authors: Pretorius, Dirk
- Date: 2019
- Subjects: Ocean zoning , Marine ecology -- Indian Ocean Sea turtles -- Indian Ocean Marine animals -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43303 , vital:36787
- Description: The conflict between sea turtles and the numerous socio-economic developments in the Southwestern Indian Ocean (SWIO) are set to intensify as countries are looking to develop their ocean-based economies. The Hydrocarbon Exploration and Production (HEP) industry is of particular importance, since many of the SWIO governments view it as catalyst for development. This has raised concerns about potentially significant environmental impacts from the HEP industry, to sea turtles and their habitats, based on international examples where sea turtles have been severely negatively impacted upon, like the Deepwater Horizon spill in the Gulf of Mexico. Given that the four sea turtles species in the SWIO are listed on the IUCN Red List of threatened species, the aim of this study was to derive priority areas for sea turtles in the face of HEP, that could be used in an ocean zoning strategy for sustainable economic development of HEP in the SWIO region. To achieve this, the study spatially represented the main life-history stages of sea turtles, i.e. the breeding, migrating and foraging areas of Caretta caretta (loggerhead turtles), Dermochelys coriacea (leatherback turtles), Chelonia mydas (green turtles) and Eretmochelys imbricata (hawksbill turtles), within a telemetry derived distribution for each species. This spatial representation was used to quantify the extent of Marine Protected Areas (MPAs) conserving sea turtles in the SWIO, which revealed that sea turtle breeding areas were well represented in MPAs, including C. caretta (~40 %), C. mydas (~53 %), E. imbricata (~59 %) and D. coriacea (~22 %), the latter being least protected by MPAs during breeding, possibly due to a far greater extent of their internesting areas than the other three species. MPA coverage of breeding areas could be positively correlated to the increasing population trends of C. caretta and C. mydas in the SWIO, and therefore the assumption was made that increasing population trends of sea turtles are in part related to MPA protection of their breeding areas. In addition, the potential impacts on sea turtles from existing and proposed HEP developments were assessed and mapped by using a novel, species-specific rating index. The results revealed the extensive nature of potential water pollution impacts on sea turtles, constituting 16 of the top 28 most significant impacts from HEP on sea turtles. Other significant impacts on sea turtles associated with the HEP industry, included habitat destruction, light pollution and noise pollution. Importantly, this study found that ~70 % of all potential HEP impacts (irrespective of significance) on adult nesting sea turtles could be avoided if seasonal sea turtle movement during critical life stages are included as species-specific HEP mitigation measures. The data and maps on the main life-history stages of sea turtles, and the potential cumulative impacts from the HEP industry, were used in a Systematic Conservation Planning process, to derive a concept ocean zoning. As final outcome of this study, the concept ocean zoning highlighted areas where increased protection to sea turtles, and management of the conflict between sea turtles and the HEP industry, will be required if the HEP industry is to develop in a sustainable manner in the SWIO.
- Full Text:
- Date Issued: 2019
- Authors: Pretorius, Dirk
- Date: 2019
- Subjects: Ocean zoning , Marine ecology -- Indian Ocean Sea turtles -- Indian Ocean Marine animals -- Ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43303 , vital:36787
- Description: The conflict between sea turtles and the numerous socio-economic developments in the Southwestern Indian Ocean (SWIO) are set to intensify as countries are looking to develop their ocean-based economies. The Hydrocarbon Exploration and Production (HEP) industry is of particular importance, since many of the SWIO governments view it as catalyst for development. This has raised concerns about potentially significant environmental impacts from the HEP industry, to sea turtles and their habitats, based on international examples where sea turtles have been severely negatively impacted upon, like the Deepwater Horizon spill in the Gulf of Mexico. Given that the four sea turtles species in the SWIO are listed on the IUCN Red List of threatened species, the aim of this study was to derive priority areas for sea turtles in the face of HEP, that could be used in an ocean zoning strategy for sustainable economic development of HEP in the SWIO region. To achieve this, the study spatially represented the main life-history stages of sea turtles, i.e. the breeding, migrating and foraging areas of Caretta caretta (loggerhead turtles), Dermochelys coriacea (leatherback turtles), Chelonia mydas (green turtles) and Eretmochelys imbricata (hawksbill turtles), within a telemetry derived distribution for each species. This spatial representation was used to quantify the extent of Marine Protected Areas (MPAs) conserving sea turtles in the SWIO, which revealed that sea turtle breeding areas were well represented in MPAs, including C. caretta (~40 %), C. mydas (~53 %), E. imbricata (~59 %) and D. coriacea (~22 %), the latter being least protected by MPAs during breeding, possibly due to a far greater extent of their internesting areas than the other three species. MPA coverage of breeding areas could be positively correlated to the increasing population trends of C. caretta and C. mydas in the SWIO, and therefore the assumption was made that increasing population trends of sea turtles are in part related to MPA protection of their breeding areas. In addition, the potential impacts on sea turtles from existing and proposed HEP developments were assessed and mapped by using a novel, species-specific rating index. The results revealed the extensive nature of potential water pollution impacts on sea turtles, constituting 16 of the top 28 most significant impacts from HEP on sea turtles. Other significant impacts on sea turtles associated with the HEP industry, included habitat destruction, light pollution and noise pollution. Importantly, this study found that ~70 % of all potential HEP impacts (irrespective of significance) on adult nesting sea turtles could be avoided if seasonal sea turtle movement during critical life stages are included as species-specific HEP mitigation measures. The data and maps on the main life-history stages of sea turtles, and the potential cumulative impacts from the HEP industry, were used in a Systematic Conservation Planning process, to derive a concept ocean zoning. As final outcome of this study, the concept ocean zoning highlighted areas where increased protection to sea turtles, and management of the conflict between sea turtles and the HEP industry, will be required if the HEP industry is to develop in a sustainable manner in the SWIO.
- Full Text:
- Date Issued: 2019
Yield responses, mineral levels of forages and soil in old arable land planted to four legume pasture species in Lushington communal area, South Africa
- Authors: Gulwa, Unathi
- Date: 2017
- Subjects: Forage plants -- South Africa -- Eastern Cape Minerals in animal nutrition Communal rangelands -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2799 , vital:28091
- Description: This study was conducted in the old arable land located in Lushington communal area in the Eastern Cape province of South Africa. The objectives of the study were to assess the effect of legume introduction on biomass yield, forage and soil mineral levels of the arable lands planted to four leguminous pastures in four seasons. Planting was done in March and October 2008 in Lushington. All legumes were subjected to grow under rain fed conditions. Trifolium vesiculosum (arrowleaf clover), Lespedeza cuneata (sericea lespedeza), Trifolium repens (white clover) and Lotus corniculatus (birdsfoot trefoil) are the four forage legume species that were sampled for the purposes of this study. The four legume species persisted out of the fourteen species that were initially tested for adaptability and persistence in the environmental conditions of Lushington communal area. The legumes, grasses and soils from these legume plots were sampled to determine the effect of legume introduction on the forage yield, mineral contents of the companion grasses and soils over four seasons. Plant and soil samples were collected once in spring (November) 2013, summer (February), autumn (March) and winter (May) 2014 for biomass production, macro and micronutrients determination. Results indicated that legume inclusion and season affected (P < 0.05) the total dry matter (TDM) yield production. Plots with Lespedeza cuneata had the highest TDM (1843 kg/ha) and control plots had the least dry matter production (1091 kg/ha). Summer season provided the highest (P < 0.05) TDM compared to the other seasons. Both legume and grass quality was also affected (P < 0.05) by legume inclusion in different seasons. Accordingly, grasses harvested from Trifolium repens plot showed higher CP level (10.90 percent) than those harvested from other plots whereas the lowest grass CP content (6.90 percent) was measured in the control treatment. L. cuneate had the highest (P < 0.05) CP level (11.00 percent) and T. repens had the least CP (6.63 percent) level. Grasses harvested in autumn had the highest (P < 0.05) CP level (12.50 percent) and those harvested in winter had the least CP level (4.60 percent). Similarly, all legume pastures harvested in spring had superior (P < 0.05) CP (10.80 percent) levels and those harvested in winter had the least CP (3.50 percent) level. Legume inclusion had an effect (P < 0.05) on both grass and legume macro nutrient contents. Trifolium repens plot had the highest grass K (1.07 percent), Ca (1.50 percent) and Mg (1.83 percent), whereas there were lower K (0.12 percent), Ca (1.25 percent) and Mg (1.08 percent) contents in grasses harvested from the control and T. vesiculosum plots, respectively. In legumes, macro nutrient concentrations: K (0.68 percent), Ca (1.75 percent) were superior in the T. vesiculosum plot in comparison to other plots. Season also affected (P < 0.05) both grass and legume macro nutrient content. There was higher K (0.90 percent), Ca (1.30 percent) and Mg (0.94 percent) content in grasses harvested in autumn whereas there were lower levels in winter harvests. In legumes, superior K (0.74 percent) and Mg (1.87 percent) content were attained during spring while the least were measured in winter (0.07 percent) and autumn (0.75 percent), respectively. Likewise, both legume inclusion and season had an significant effect (P < 0.05) on the forages micronutrient levels. During spring, there was superior soil P content (36.28 mg/kg) while during autumn; there was less P (22.58 mg/kg) content. The highest SOC level (1.49 percent) was measured in the T. repens plot whereas the lowest SOC (1.15 percent) was attained in the control plot. The results of this study showed that grass legume mixtures produced forages with high nutrient content and herbage yield. Legume planting in the old arable lands has a potential to improve soil quality parameters such as soil P and SOC content.
- Full Text:
- Date Issued: 2017
- Authors: Gulwa, Unathi
- Date: 2017
- Subjects: Forage plants -- South Africa -- Eastern Cape Minerals in animal nutrition Communal rangelands -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/2799 , vital:28091
- Description: This study was conducted in the old arable land located in Lushington communal area in the Eastern Cape province of South Africa. The objectives of the study were to assess the effect of legume introduction on biomass yield, forage and soil mineral levels of the arable lands planted to four leguminous pastures in four seasons. Planting was done in March and October 2008 in Lushington. All legumes were subjected to grow under rain fed conditions. Trifolium vesiculosum (arrowleaf clover), Lespedeza cuneata (sericea lespedeza), Trifolium repens (white clover) and Lotus corniculatus (birdsfoot trefoil) are the four forage legume species that were sampled for the purposes of this study. The four legume species persisted out of the fourteen species that were initially tested for adaptability and persistence in the environmental conditions of Lushington communal area. The legumes, grasses and soils from these legume plots were sampled to determine the effect of legume introduction on the forage yield, mineral contents of the companion grasses and soils over four seasons. Plant and soil samples were collected once in spring (November) 2013, summer (February), autumn (March) and winter (May) 2014 for biomass production, macro and micronutrients determination. Results indicated that legume inclusion and season affected (P < 0.05) the total dry matter (TDM) yield production. Plots with Lespedeza cuneata had the highest TDM (1843 kg/ha) and control plots had the least dry matter production (1091 kg/ha). Summer season provided the highest (P < 0.05) TDM compared to the other seasons. Both legume and grass quality was also affected (P < 0.05) by legume inclusion in different seasons. Accordingly, grasses harvested from Trifolium repens plot showed higher CP level (10.90 percent) than those harvested from other plots whereas the lowest grass CP content (6.90 percent) was measured in the control treatment. L. cuneate had the highest (P < 0.05) CP level (11.00 percent) and T. repens had the least CP (6.63 percent) level. Grasses harvested in autumn had the highest (P < 0.05) CP level (12.50 percent) and those harvested in winter had the least CP level (4.60 percent). Similarly, all legume pastures harvested in spring had superior (P < 0.05) CP (10.80 percent) levels and those harvested in winter had the least CP (3.50 percent) level. Legume inclusion had an effect (P < 0.05) on both grass and legume macro nutrient contents. Trifolium repens plot had the highest grass K (1.07 percent), Ca (1.50 percent) and Mg (1.83 percent), whereas there were lower K (0.12 percent), Ca (1.25 percent) and Mg (1.08 percent) contents in grasses harvested from the control and T. vesiculosum plots, respectively. In legumes, macro nutrient concentrations: K (0.68 percent), Ca (1.75 percent) were superior in the T. vesiculosum plot in comparison to other plots. Season also affected (P < 0.05) both grass and legume macro nutrient content. There was higher K (0.90 percent), Ca (1.30 percent) and Mg (0.94 percent) content in grasses harvested in autumn whereas there were lower levels in winter harvests. In legumes, superior K (0.74 percent) and Mg (1.87 percent) content were attained during spring while the least were measured in winter (0.07 percent) and autumn (0.75 percent), respectively. Likewise, both legume inclusion and season had an significant effect (P < 0.05) on the forages micronutrient levels. During spring, there was superior soil P content (36.28 mg/kg) while during autumn; there was less P (22.58 mg/kg) content. The highest SOC level (1.49 percent) was measured in the T. repens plot whereas the lowest SOC (1.15 percent) was attained in the control plot. The results of this study showed that grass legume mixtures produced forages with high nutrient content and herbage yield. Legume planting in the old arable lands has a potential to improve soil quality parameters such as soil P and SOC content.
- Full Text:
- Date Issued: 2017
Woody species composition and congregant appreciation of the cultural and spiritual services provided by cemeteries and church gardens in Grahamstown, South Africa
- Authors: De Lacy, Peter James Gerard
- Date: 2015
- Subjects: Plants -- Religious aspects , Cemeteries -- South Africa -- Grahamstown , Woody plants -- South Africa -- Grahamstown , Church gardens -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4783 , http://hdl.handle.net/10962/d1016401
- Description: Urbanization has increased rapidly throughout the world. The densification of urban areas has greatly reduced the number of natural areas occurring within the urban environment as well as impacting the ecosystem services that these areas provide. Urban greening and sustainable practices have been advocated as a means to once again provide the urban population with ecosystem services. Sacred natural areas that occur in surrounding forest, temple and cemetery sites have been known harbour a variety of biological diversity, as well as provide people with a number of cultural and spiritual benefits. Much of the literature on sacred natural sites comes from rural or eastern countries, leaving a large gap in the knowledge pertaining to information on these sites in both developed nations as well as urban areas. The aim of this study was to determine the abundance and composition of woody species, as well as the spiritual and cultural significance of sacred natural sites in Grahamstown. This study defined a sacred urban area as any form of garden surrounding a church, temple or mosque, as well as cemeteries. It looked at a total of 28 church gardens, one Hindu garden, one Mosque garden and five cemeteries in Grahamstown, South Africa. For each site the area was calculated and a tree and shrub inventory was done for all individuals above 1.5 m tall. Church/cemetery age, denomination and appearance were recorded as well as soil samples collected. An ordination of the data was done to summarize the community data, relating the community variation to environmental gradients. Questionnaires were completed by congregants who attended a religious building with a garden, as well as those that were not surrounded by a garden. These questionnaires were used to determine the cultural, spiritual and aesthetic value of trees and the sacred area, as well as the perceived and felt benefits that these areas provide. Those that were completed by congregants without gardens looked to find out whether or not it was believed that these areas would improve their experiences. There was an average plant density of 106.1 woody plants per hectare, with a total of 139 different species encountered. Of these, 56 percent were exotic species. This is slightly lower than that of studies done elsewhere in the world, but may be due to the omission of non-woody ornamentals and lawn species in this study. Of the top 11 most frequently occurring species, only two were indigenous. There was generally low similarity between plant assemblages found at the different sites. A significantly positive relationship was found between site size and woody plant basal area as well as the total number of woody plants. Site age and religious denomination had little influence on woody plant density, basal area, species richness or woody plant abundance. Congregants stated that a garden surrounding a religious building improved both their spiritual and aesthetic experiences. Stated spiritual and aesthetic experience was significantly influenced by basal area, while abundance significantly influenced stated aesthetic experience. Greenery was therefore important to many of the congregants, however, the species that were present were less influential. A greater sample size from a variety of religions and sacred areas within urban environments throughout the world would prove to be an interesting comparison for future research.
- Full Text:
- Date Issued: 2015
- Authors: De Lacy, Peter James Gerard
- Date: 2015
- Subjects: Plants -- Religious aspects , Cemeteries -- South Africa -- Grahamstown , Woody plants -- South Africa -- Grahamstown , Church gardens -- South Africa -- Grahamstown
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4783 , http://hdl.handle.net/10962/d1016401
- Description: Urbanization has increased rapidly throughout the world. The densification of urban areas has greatly reduced the number of natural areas occurring within the urban environment as well as impacting the ecosystem services that these areas provide. Urban greening and sustainable practices have been advocated as a means to once again provide the urban population with ecosystem services. Sacred natural areas that occur in surrounding forest, temple and cemetery sites have been known harbour a variety of biological diversity, as well as provide people with a number of cultural and spiritual benefits. Much of the literature on sacred natural sites comes from rural or eastern countries, leaving a large gap in the knowledge pertaining to information on these sites in both developed nations as well as urban areas. The aim of this study was to determine the abundance and composition of woody species, as well as the spiritual and cultural significance of sacred natural sites in Grahamstown. This study defined a sacred urban area as any form of garden surrounding a church, temple or mosque, as well as cemeteries. It looked at a total of 28 church gardens, one Hindu garden, one Mosque garden and five cemeteries in Grahamstown, South Africa. For each site the area was calculated and a tree and shrub inventory was done for all individuals above 1.5 m tall. Church/cemetery age, denomination and appearance were recorded as well as soil samples collected. An ordination of the data was done to summarize the community data, relating the community variation to environmental gradients. Questionnaires were completed by congregants who attended a religious building with a garden, as well as those that were not surrounded by a garden. These questionnaires were used to determine the cultural, spiritual and aesthetic value of trees and the sacred area, as well as the perceived and felt benefits that these areas provide. Those that were completed by congregants without gardens looked to find out whether or not it was believed that these areas would improve their experiences. There was an average plant density of 106.1 woody plants per hectare, with a total of 139 different species encountered. Of these, 56 percent were exotic species. This is slightly lower than that of studies done elsewhere in the world, but may be due to the omission of non-woody ornamentals and lawn species in this study. Of the top 11 most frequently occurring species, only two were indigenous. There was generally low similarity between plant assemblages found at the different sites. A significantly positive relationship was found between site size and woody plant basal area as well as the total number of woody plants. Site age and religious denomination had little influence on woody plant density, basal area, species richness or woody plant abundance. Congregants stated that a garden surrounding a religious building improved both their spiritual and aesthetic experiences. Stated spiritual and aesthetic experience was significantly influenced by basal area, while abundance significantly influenced stated aesthetic experience. Greenery was therefore important to many of the congregants, however, the species that were present were less influential. A greater sample size from a variety of religions and sacred areas within urban environments throughout the world would prove to be an interesting comparison for future research.
- Full Text:
- Date Issued: 2015
Woody encroachment and plant-root soil interactions in a semi-arid savanna
- Authors: Gusha, Bukho
- Date: 2015
- Subjects: Pastures -- Management Weeds Invasive plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12139 , vital:39174
- Description: Savannas occupy 1/8 of the global land surface, support a large proportion of the world’s human population and the majority of its rangeland and livestock. Woody encroachment has been reported as the major challenge in these landscapes. This study describes the differences between three contrasting tree density classes in a semi- arid savanna with the view to developing an improved understanding of woody encroachment which is prevalent in this region. The study attempted to determine if there was a relationship between lateral root distributions at varying soil depths with increasing levels of woody encroachment, and to compare species composition and soil water profiles in these rangelands. Three homogeneous vegetation units, namely: sparsely encroached (HVU1), grassland (HVU2) and Albany thicket (HVU3) were identified for the study sites. A Trench method was used determine root biomass and a step point method was used to determine herbaceous species composition in all the HVUs. The results showed that more Decreaser species (especially Themeda triandra) were recorded in a sparsely encroached site (HVU1) and grassland site (HVU2), while Cynodon dactylon was mostly recorded in the thicket site (HVU3). Acacia karroo was mostly recorded in HVU1 while in HVU2 other woody species such as Coddia rudis and Grewia occidentalis were also recoded. HVU3 had the poorest basal cover (point to tuft distance) (22.60 cm) while HVU1 (9.93 cm) and HVU2 (7.73 cm) had moderate basal cover. The herbaceous standing biomass was significantly different across the HVUs. HVU3 was higher (1206.15 kg ha-1) than HVU1 (942.43 kg ha-1) and HVU2 (677.10 kg ha-1). The soil moisture content was significantly different between the HVUs, but was not significantly different between the depths (p< 0.05). High soil moisture content was recorded in HVU3 compared to other HVUs. The results of Analysis of Variance (ANOVA) showed that soil depth and the type of homogenous vegetation unit (HVU) had significant effects (p<0.01) on root biomass. The pair wise t-test showed that there were no significant difference in root biomass between sparsely encroached (HVU1) and grassland (HVU2) sites (p>0.05), but there were significant differences in root biomass between grassland (HVU2) and thicket (HVU3) site (p<0.05). The mean for total root biomass found in the study was 2.66 kg m-2. In all the trenches most of the root biomass was found in depth 1 (0-30 cm) which was 2.43 kg m-2followed by 1.32 kg m-2 in depth 2 (30-60 cm) and 0.49 kg m-2 in depth 3 (60-90 cm). According to the results on species composition, herbaceous biomass, basal cover, soil moisture content and the root biomass, Kwezana communal rangeland has a potential of running a sustainable livestock production enterprise if proper management practices can be implemented. To improve the rangelands of Kwezana communal rangelands, management such as proper resting, burning, proper stocking rates and physically clearing of bushes should be considered.
- Full Text:
- Date Issued: 2015
- Authors: Gusha, Bukho
- Date: 2015
- Subjects: Pastures -- Management Weeds Invasive plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12139 , vital:39174
- Description: Savannas occupy 1/8 of the global land surface, support a large proportion of the world’s human population and the majority of its rangeland and livestock. Woody encroachment has been reported as the major challenge in these landscapes. This study describes the differences between three contrasting tree density classes in a semi- arid savanna with the view to developing an improved understanding of woody encroachment which is prevalent in this region. The study attempted to determine if there was a relationship between lateral root distributions at varying soil depths with increasing levels of woody encroachment, and to compare species composition and soil water profiles in these rangelands. Three homogeneous vegetation units, namely: sparsely encroached (HVU1), grassland (HVU2) and Albany thicket (HVU3) were identified for the study sites. A Trench method was used determine root biomass and a step point method was used to determine herbaceous species composition in all the HVUs. The results showed that more Decreaser species (especially Themeda triandra) were recorded in a sparsely encroached site (HVU1) and grassland site (HVU2), while Cynodon dactylon was mostly recorded in the thicket site (HVU3). Acacia karroo was mostly recorded in HVU1 while in HVU2 other woody species such as Coddia rudis and Grewia occidentalis were also recoded. HVU3 had the poorest basal cover (point to tuft distance) (22.60 cm) while HVU1 (9.93 cm) and HVU2 (7.73 cm) had moderate basal cover. The herbaceous standing biomass was significantly different across the HVUs. HVU3 was higher (1206.15 kg ha-1) than HVU1 (942.43 kg ha-1) and HVU2 (677.10 kg ha-1). The soil moisture content was significantly different between the HVUs, but was not significantly different between the depths (p< 0.05). High soil moisture content was recorded in HVU3 compared to other HVUs. The results of Analysis of Variance (ANOVA) showed that soil depth and the type of homogenous vegetation unit (HVU) had significant effects (p<0.01) on root biomass. The pair wise t-test showed that there were no significant difference in root biomass between sparsely encroached (HVU1) and grassland (HVU2) sites (p>0.05), but there were significant differences in root biomass between grassland (HVU2) and thicket (HVU3) site (p<0.05). The mean for total root biomass found in the study was 2.66 kg m-2. In all the trenches most of the root biomass was found in depth 1 (0-30 cm) which was 2.43 kg m-2followed by 1.32 kg m-2 in depth 2 (30-60 cm) and 0.49 kg m-2 in depth 3 (60-90 cm). According to the results on species composition, herbaceous biomass, basal cover, soil moisture content and the root biomass, Kwezana communal rangeland has a potential of running a sustainable livestock production enterprise if proper management practices can be implemented. To improve the rangelands of Kwezana communal rangelands, management such as proper resting, burning, proper stocking rates and physically clearing of bushes should be considered.
- Full Text:
- Date Issued: 2015
Woody encroachment and plant-root soil interactions in a semi-arid savanna
- Authors: Gusha, Bukho
- Date: 2015
- Subjects: Pastures -- Management Weeds Invasive plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12053 , vital:39131
- Description: Savannas occupy 1/8 of the global land surface, support a large proportion of the world’s human population and the majority of its rangeland and livestock. Woody encroachment has been reported as the major challenge in these landscapes. This study describes the differences between three contrasting tree density classes in a semi- arid savanna with the view to developing an improved understanding of woody encroachment which is prevalent in this region. The study attempted to determine if there was a relationship between lateral root distributions at varying soil depths with increasing levels of woody encroachment, and to compare species composition and soil water profiles in these rangelands. Three homogeneous vegetation units, namely: sparsely encroached (HVU1), grassland (HVU2) and Albany thicket (HVU3) were identified for the study sites. A Trench method was used determine root biomass and a step point method was used to determine herbaceousspecies composition in all the HVUs. The results showed that more Decreaser species (especially Themeda triandra) were recorded in a sparsely encroached site (HVU1) and grassland site (HVU2), while Cynodon dactylon was mostly recorded in the thicket site (HVU3). Acacia karroo was mostly recorded in HVU1 while in HVU2 other woody species such as Coddia rudis and Grewia occidentalis were also recoded. HVU3 had the poorest basal cover (point to tuft distance) (22.60 cm) while HVU1 (9.93 cm) and HVU2 (7.73 cm) had moderate basal cover. The herbaceous standing biomass was significantly different across the HVUs. HVU3 was higher (1206.15 kg ha-1) than HVU1 (942.43 kg ha-1) and HVU2 (677.10 kg ha-1). The soil moisture content was significantly different between the HVUs, but was not significantly different between the depths (p< 0.05). High soil moisture content was recorded in HVU3 compared to other HVUs. The results of Analysis of Variance (ANOVA) showed that soil depth and the type of homogenous vegetation unit (HVU) had significant effects (p<0.01) on root biomass. The pair wise t-test showed that there were no significant difference in root biomass between sparsely encroached (HVU1) and grassland (HVU2) sites (p>0.05), but there were significant differences in root biomass between grassland (HVU2) and thicket (HVU3) site (p<0.05). The mean for total root biomass found in the study was 2.66 kg m-2. In all the trenches most of the root biomass was found in depth 1 (0-30 cm) which was 2.43 kg m-2followed by 1.32 kg m-2 in depth 2 (30-60 cm) and 0.49 kg m-2 in depth 3 (60-90 cm). According to the results on species composition, herbaceous biomass, basal cover, soil moisture content and the root biomass, Kwezana communal rangeland has a potential of running a sustainable livestock production enterprise if proper management practices can be implemented. To improve the rangelands of Kwezana communal rangelands management such as proper resting, burning, proper stocking rates and physically clearing of bushes should be considered.
- Full Text:
- Date Issued: 2015
- Authors: Gusha, Bukho
- Date: 2015
- Subjects: Pastures -- Management Weeds Invasive plants
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/12053 , vital:39131
- Description: Savannas occupy 1/8 of the global land surface, support a large proportion of the world’s human population and the majority of its rangeland and livestock. Woody encroachment has been reported as the major challenge in these landscapes. This study describes the differences between three contrasting tree density classes in a semi- arid savanna with the view to developing an improved understanding of woody encroachment which is prevalent in this region. The study attempted to determine if there was a relationship between lateral root distributions at varying soil depths with increasing levels of woody encroachment, and to compare species composition and soil water profiles in these rangelands. Three homogeneous vegetation units, namely: sparsely encroached (HVU1), grassland (HVU2) and Albany thicket (HVU3) were identified for the study sites. A Trench method was used determine root biomass and a step point method was used to determine herbaceousspecies composition in all the HVUs. The results showed that more Decreaser species (especially Themeda triandra) were recorded in a sparsely encroached site (HVU1) and grassland site (HVU2), while Cynodon dactylon was mostly recorded in the thicket site (HVU3). Acacia karroo was mostly recorded in HVU1 while in HVU2 other woody species such as Coddia rudis and Grewia occidentalis were also recoded. HVU3 had the poorest basal cover (point to tuft distance) (22.60 cm) while HVU1 (9.93 cm) and HVU2 (7.73 cm) had moderate basal cover. The herbaceous standing biomass was significantly different across the HVUs. HVU3 was higher (1206.15 kg ha-1) than HVU1 (942.43 kg ha-1) and HVU2 (677.10 kg ha-1). The soil moisture content was significantly different between the HVUs, but was not significantly different between the depths (p< 0.05). High soil moisture content was recorded in HVU3 compared to other HVUs. The results of Analysis of Variance (ANOVA) showed that soil depth and the type of homogenous vegetation unit (HVU) had significant effects (p<0.01) on root biomass. The pair wise t-test showed that there were no significant difference in root biomass between sparsely encroached (HVU1) and grassland (HVU2) sites (p>0.05), but there were significant differences in root biomass between grassland (HVU2) and thicket (HVU3) site (p<0.05). The mean for total root biomass found in the study was 2.66 kg m-2. In all the trenches most of the root biomass was found in depth 1 (0-30 cm) which was 2.43 kg m-2followed by 1.32 kg m-2 in depth 2 (30-60 cm) and 0.49 kg m-2 in depth 3 (60-90 cm). According to the results on species composition, herbaceous biomass, basal cover, soil moisture content and the root biomass, Kwezana communal rangeland has a potential of running a sustainable livestock production enterprise if proper management practices can be implemented. To improve the rangelands of Kwezana communal rangelands management such as proper resting, burning, proper stocking rates and physically clearing of bushes should be considered.
- Full Text:
- Date Issued: 2015
Within- and between-beach variation in intertidal macrofaunal communities inhabiting two Transkei sandy beaches
- Authors: Dreyer, Nicolaas Burger
- Date: 2008
- Subjects: Intertidal animals -- Ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10700 , http://hdl.handle.net/10948/1070 , Intertidal animals -- Ecology -- South Africa
- Description: Until recently most sandy beach studies have made use of snapshot samples but the validity of this approach has been widely questioned. In this study we attempt to resolve this issue by repeatedly sampling two beaches using a stratified random design. Three sampling sessions took place, each approximately six months apart. The three sites on the first beach were selected according to the type of beach (reflective, intermediate and dissipative) with each morphological type duplicated on the second beach. Many of the physical variables measured had significant differences between the sampling sessions but only a few were significantly different between the Sites. Very few of the individual physical variables had significant relationships with the sandy beach macrofaunal abundance and density. However, composite indices had a greater number of significant relationships with the macrofaunal abundance and density. Also very few significant relationships were seen between the species richness and the physical variables of the beaches studied. Effluent line crossing frequency was the only physical variable that could predict species richness but it was considered a weak predictor. Changes in the zonation patterns within and between beaches were also investigated. The highest concentration of taxa and individuals was found near the low-water mark with a gradual reduction of both towards the high-water mark. Some of the sandy beach community variables (abundance, density and species richness) showed significant difference between the sampling sessions but no significant differences were seen between the two beaches. The presence of three zones was noted using MDS plots and Cluster diagrams. However, using a SIMPER analyses, four zones with the possibility of a fifth was noted.
- Full Text:
- Date Issued: 2008
- Authors: Dreyer, Nicolaas Burger
- Date: 2008
- Subjects: Intertidal animals -- Ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10700 , http://hdl.handle.net/10948/1070 , Intertidal animals -- Ecology -- South Africa
- Description: Until recently most sandy beach studies have made use of snapshot samples but the validity of this approach has been widely questioned. In this study we attempt to resolve this issue by repeatedly sampling two beaches using a stratified random design. Three sampling sessions took place, each approximately six months apart. The three sites on the first beach were selected according to the type of beach (reflective, intermediate and dissipative) with each morphological type duplicated on the second beach. Many of the physical variables measured had significant differences between the sampling sessions but only a few were significantly different between the Sites. Very few of the individual physical variables had significant relationships with the sandy beach macrofaunal abundance and density. However, composite indices had a greater number of significant relationships with the macrofaunal abundance and density. Also very few significant relationships were seen between the species richness and the physical variables of the beaches studied. Effluent line crossing frequency was the only physical variable that could predict species richness but it was considered a weak predictor. Changes in the zonation patterns within and between beaches were also investigated. The highest concentration of taxa and individuals was found near the low-water mark with a gradual reduction of both towards the high-water mark. Some of the sandy beach community variables (abundance, density and species richness) showed significant difference between the sampling sessions but no significant differences were seen between the two beaches. The presence of three zones was noted using MDS plots and Cluster diagrams. However, using a SIMPER analyses, four zones with the possibility of a fifth was noted.
- Full Text:
- Date Issued: 2008
Wind damage impacts on Eucalyptus species performance in South Africa
- Authors: Hechter, Heinrich
- Date: 2020
- Subjects: Commercial forests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48368 , vital:40853
- Description: Commercial forestry plantations in South Africa play an important role in the economy of the country, contributing 1.2% towards the gross domestic product, as well as with job creation in rural communities. Currently plantation forests cover 1% (1.2 million hectares) of the South African land surface, of which ±75 000 hectares (±43 000 hectares to Eucalyptus species) are re-established each year. Different timber companies afforest areas with different species to satisfy specific management objectives, with the two main objectives being for either the production of saw-timber or pulpwood. Species of the Eucalyptus genera are preferred as they are fast growing and have desirable wood and pulping properties. However, their productive potential can be negatively impacted by numerous abiotic and biotic risk factors. Of the various risk factors that forest stands are exposed to, wind and wind-related tree damage has received very little attention, both nationally and internationally. Wind-related tree damage may result in wind-throw (uprooting or stem breakage), or trees that tilt (lean off vertical). Trees that are tilting can recover to an upright position, but are likely to retain some level of stem sinuosity or butt-sweep. Although strong winds increase the risk of tree damage, a number of other factors can also act to predispose trees to wind-related damage. These include choice of planting stock (genotype and type of plant stock), planting practices (including soil cultivation), site factors (wind exposure, rainfall, soil texture and soil fertility) or excessive weed competition. Most of the literature dealing with wind-related tree damage has focused on trees growing in natural forests, whereas trees in natural forests differ from forest grown plantation trees in terms of above- and below-ground morphological differences, as well as the stability factors of the trees. There is a need to not only understand the impacts of severe (catastrophic) wind events on mature trees, but also to test management strategies that prevent, or minimize damage prior to any severe wind events. Two existing eucalypt trials were used to provide information on the influence of selected re-establishment silvicultural practices on short-term pulpwood and long-term saw-timber survival, growth and uniformity when influenced by catastrophic wind events, within South Africa.
- Full Text:
- Date Issued: 2020
- Authors: Hechter, Heinrich
- Date: 2020
- Subjects: Commercial forests -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48368 , vital:40853
- Description: Commercial forestry plantations in South Africa play an important role in the economy of the country, contributing 1.2% towards the gross domestic product, as well as with job creation in rural communities. Currently plantation forests cover 1% (1.2 million hectares) of the South African land surface, of which ±75 000 hectares (±43 000 hectares to Eucalyptus species) are re-established each year. Different timber companies afforest areas with different species to satisfy specific management objectives, with the two main objectives being for either the production of saw-timber or pulpwood. Species of the Eucalyptus genera are preferred as they are fast growing and have desirable wood and pulping properties. However, their productive potential can be negatively impacted by numerous abiotic and biotic risk factors. Of the various risk factors that forest stands are exposed to, wind and wind-related tree damage has received very little attention, both nationally and internationally. Wind-related tree damage may result in wind-throw (uprooting or stem breakage), or trees that tilt (lean off vertical). Trees that are tilting can recover to an upright position, but are likely to retain some level of stem sinuosity or butt-sweep. Although strong winds increase the risk of tree damage, a number of other factors can also act to predispose trees to wind-related damage. These include choice of planting stock (genotype and type of plant stock), planting practices (including soil cultivation), site factors (wind exposure, rainfall, soil texture and soil fertility) or excessive weed competition. Most of the literature dealing with wind-related tree damage has focused on trees growing in natural forests, whereas trees in natural forests differ from forest grown plantation trees in terms of above- and below-ground morphological differences, as well as the stability factors of the trees. There is a need to not only understand the impacts of severe (catastrophic) wind events on mature trees, but also to test management strategies that prevent, or minimize damage prior to any severe wind events. Two existing eucalypt trials were used to provide information on the influence of selected re-establishment silvicultural practices on short-term pulpwood and long-term saw-timber survival, growth and uniformity when influenced by catastrophic wind events, within South Africa.
- Full Text:
- Date Issued: 2020
White rhinoceros populations in the Eastern Cape: distribution, performance and diet
- Authors: Kraai, Manqhai
- Date: 2010
- Subjects: Rhinoceroses -- South Africa -- Eastern Cape , Rhinoceroses -- Habitat -- South Africa -- Eastern Cape , Rhinoceroses -- Behavior -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10692 , http://hdl.handle.net/10948/1297 , Rhinoceroses -- South Africa -- Eastern Cape , Rhinoceroses -- Habitat -- South Africa -- Eastern Cape , Rhinoceroses -- Behavior -- South Africa -- Eastern Cape
- Description: White rhino populations did not occur historically in the Eastern Cape, South Africa (Skead 2007). They have, however, been introduced into a number of reserves within the Eastern Cape for reasons such as conservation, ecotourism and hunting. Based on the literature on the species, it was hypothesized that white rhinoceros would have been introduced in grass-rich habitats, as they are bulk grazers. White rhinoceros populations were further assessed in terms of population establishment by outlining their distribution and performance since introductions and this was done by extracting intercalving intervals from the literature of native populations and comparing such to the Eastern Cape intercalving intervals, extracted from data obtained from landowners. Finally, the diet of white rhinoceros was quantified, in order to identify plant species potentially at risk from white rhino herbivory using Shamwari Private Game Reserve as a study site. The distribution of white rhino in the Eastern Cape varies in terms of habitat and vegetation types. The majority (62%) of white rhino are located in grass-poor habitats and are primarily there for ecotourism purposes with only a small percentage kept for conservation purposes in the state reserves. Limited data for intercalving intervals of the white rhino in Eastern Cape are comparable to those of populations in the natural range. The ex situ conservation of white rhino in the Eastern Cape proved to be a success as population numbers have increased markedly since the first survey was conducted (Buijs 1999). The diet section of this study showed that white rhino are highly selective grazers even in a grass-limiting habitat which is dominated by browse. Twenty-five principal dietary items were identified in their diet, with only six being preferred in autumn. These are thus the plant species that could be the most vulnerable to white rhino herbivory. Supplementary food provision plays a big part of the feeding scheme of white rhino in Shamwari Private Game Reserve during the winter season, revealing the little confidence that the management has on natural resource availability to the animals at this time. These findings support the value of the Eastern Cape for ex situ conservation of white rhino, and highlight plant species potentially at risk. There is a need for further research on the population performance of these animals, and the plants identified here need to be monitored to assess white rhino impact on the vegetation
- Full Text:
- Date Issued: 2010
- Authors: Kraai, Manqhai
- Date: 2010
- Subjects: Rhinoceroses -- South Africa -- Eastern Cape , Rhinoceroses -- Habitat -- South Africa -- Eastern Cape , Rhinoceroses -- Behavior -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10692 , http://hdl.handle.net/10948/1297 , Rhinoceroses -- South Africa -- Eastern Cape , Rhinoceroses -- Habitat -- South Africa -- Eastern Cape , Rhinoceroses -- Behavior -- South Africa -- Eastern Cape
- Description: White rhino populations did not occur historically in the Eastern Cape, South Africa (Skead 2007). They have, however, been introduced into a number of reserves within the Eastern Cape for reasons such as conservation, ecotourism and hunting. Based on the literature on the species, it was hypothesized that white rhinoceros would have been introduced in grass-rich habitats, as they are bulk grazers. White rhinoceros populations were further assessed in terms of population establishment by outlining their distribution and performance since introductions and this was done by extracting intercalving intervals from the literature of native populations and comparing such to the Eastern Cape intercalving intervals, extracted from data obtained from landowners. Finally, the diet of white rhinoceros was quantified, in order to identify plant species potentially at risk from white rhino herbivory using Shamwari Private Game Reserve as a study site. The distribution of white rhino in the Eastern Cape varies in terms of habitat and vegetation types. The majority (62%) of white rhino are located in grass-poor habitats and are primarily there for ecotourism purposes with only a small percentage kept for conservation purposes in the state reserves. Limited data for intercalving intervals of the white rhino in Eastern Cape are comparable to those of populations in the natural range. The ex situ conservation of white rhino in the Eastern Cape proved to be a success as population numbers have increased markedly since the first survey was conducted (Buijs 1999). The diet section of this study showed that white rhino are highly selective grazers even in a grass-limiting habitat which is dominated by browse. Twenty-five principal dietary items were identified in their diet, with only six being preferred in autumn. These are thus the plant species that could be the most vulnerable to white rhino herbivory. Supplementary food provision plays a big part of the feeding scheme of white rhino in Shamwari Private Game Reserve during the winter season, revealing the little confidence that the management has on natural resource availability to the animals at this time. These findings support the value of the Eastern Cape for ex situ conservation of white rhino, and highlight plant species potentially at risk. There is a need for further research on the population performance of these animals, and the plants identified here need to be monitored to assess white rhino impact on the vegetation
- Full Text:
- Date Issued: 2010
Wheat stress responses during Russian wheat aphid and Bird Cherry Oat aphid infestation: an analysis of differential protein regulation during plant biotic stress responses
- Louw, Cassandra Alexandrovna
- Authors: Louw, Cassandra Alexandrovna
- Date: 2007
- Subjects: Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3995 , http://hdl.handle.net/10962/d1004055 , Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Description: Plants possess a complex and poorly understood network of defence mechanisms that enable them to counteract the effects of abiotic and biotic stress. Aphid phloem feeding is source of biotic stress in plants. Russian wheat aphid and Bird Cherry-Oat aphid feeding cause significant losses in the annual wheat crop, and control by conventional methods such as pesticide application, has proved to be ineffective. Infestation by the Russian wheat aphid has a particularly devastating effect in South Africa. Aphid-resistant wheat cultivars have been identified but an incomplete understanding of the mechanism of the plant’s resistance thwarts the development of improved cultivars. A two-dimensional gel electrophoresis method was developed, partially optimised and validated in order to determine the effect of Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding on the Betta and Betta DN wheat proteome. Differentially expressed proteins that were up or down regulated more than two fold were identified using PDQuest™ Basic software and matched to known wheat proteins stored in the SwissProt protein database on the basis of their molecular mass and isolectric point. Initial analysis of the differential protein expression of Betta and Betta DN wheat in response to Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding at different growth stages revealed that younger plants display higher levels of resistance than older plants. Feeding by the Bird-Cherry Oat aphid does not result in the upregulation of proteins implicated in a defence response, which indicates that the damage incurred by the plant due to feeding by this aphid is not enough to trigger a classic defence response. Feeding by the more damaging Russian wheat aphid resulted in a stress response in susceptible wheat cultivar Betta, and a defence response in resistant wheat cultivar Betta DN. The infestation of Betta DN resulted in the upregulation of putative thaumatins and amylase trypsin inhibitors, indicating that the Betta DN resistance response could be due to the combined effect of protease inhibitors that discourage aphid phloem feeding and the activation of the salicylic acid and jasmonic acid plant defence pathways.
- Full Text:
- Date Issued: 2007
- Authors: Louw, Cassandra Alexandrovna
- Date: 2007
- Subjects: Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3995 , http://hdl.handle.net/10962/d1004055 , Russian wheat aphid , Plants, Effect of stress on , Wheat -- Diseases and pests , Rhopalosiphum , Plant proteins
- Description: Plants possess a complex and poorly understood network of defence mechanisms that enable them to counteract the effects of abiotic and biotic stress. Aphid phloem feeding is source of biotic stress in plants. Russian wheat aphid and Bird Cherry-Oat aphid feeding cause significant losses in the annual wheat crop, and control by conventional methods such as pesticide application, has proved to be ineffective. Infestation by the Russian wheat aphid has a particularly devastating effect in South Africa. Aphid-resistant wheat cultivars have been identified but an incomplete understanding of the mechanism of the plant’s resistance thwarts the development of improved cultivars. A two-dimensional gel electrophoresis method was developed, partially optimised and validated in order to determine the effect of Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding on the Betta and Betta DN wheat proteome. Differentially expressed proteins that were up or down regulated more than two fold were identified using PDQuest™ Basic software and matched to known wheat proteins stored in the SwissProt protein database on the basis of their molecular mass and isolectric point. Initial analysis of the differential protein expression of Betta and Betta DN wheat in response to Russian wheat aphid and Bird Cherry-Oat aphid phloem feeding at different growth stages revealed that younger plants display higher levels of resistance than older plants. Feeding by the Bird-Cherry Oat aphid does not result in the upregulation of proteins implicated in a defence response, which indicates that the damage incurred by the plant due to feeding by this aphid is not enough to trigger a classic defence response. Feeding by the more damaging Russian wheat aphid resulted in a stress response in susceptible wheat cultivar Betta, and a defence response in resistant wheat cultivar Betta DN. The infestation of Betta DN resulted in the upregulation of putative thaumatins and amylase trypsin inhibitors, indicating that the Betta DN resistance response could be due to the combined effect of protease inhibitors that discourage aphid phloem feeding and the activation of the salicylic acid and jasmonic acid plant defence pathways.
- Full Text:
- Date Issued: 2007
What limits an invasive biotic and abiotic effects on the distribution of the invasive mussel mytilus galloprovincialis on the South African coastline
- Authors: Hall, Madison
- Date: 2015
- Subjects: Perna , Mytilus galloprovincialis , Mussels -- South Africa , Introduced organisms -- Environmental aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5927 , http://hdl.handle.net/10962/d1017805
- Full Text:
- Date Issued: 2015
- Authors: Hall, Madison
- Date: 2015
- Subjects: Perna , Mytilus galloprovincialis , Mussels -- South Africa , Introduced organisms -- Environmental aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5927 , http://hdl.handle.net/10962/d1017805
- Full Text:
- Date Issued: 2015
Weight gain in hospitalised low birth weight (LBW) premature infants receiving breast milk or breast milk with human milk fortifier in the Nelson Mandela Bay Health District
- Authors: Wicomb, Ra-eesa
- Date: 2018
- Subjects: Premature infants -- South Africa -- Nelson Mandela Bay Municipality , Birth weight, Low -- South Africa -- Nelson Mandela Bay Municipality Birth weight -- South Africa -- Nelson Mandela Bay Municipality Infants -- Nutrition Children -- Nutrition -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23327 , vital:30529
- Description: Rationale: Worldwide, hospitals with premature units have one generalised objective, i.e. to achieve postnatal growth and body composition similar to that of a normal foetus of similar gestational age. Optimal nutrition leads to optimal neurodevelopment and breastfeeding (BF) is known as the golden standard for infant nutrition. Human breast milk (BM) has significant value for preterm and term infants and is of special benefit to HIV infected mothers. Maternal supplementation is provided as part of the standard protocol in certain hospitals in the Eastern Cape province to those mothers who breastfeed their low birth weight (LBW) infants after delivery. human milk fortifier (HMF) is a nutritional supplement that is added to expressed breast milk for feeding preterm infants in order to meet their high energy and protein needs and therefore supporting the recommended growth velocity of 10g/kg/day-15g/kg/day. Some hospitals within South Africa provide HMF to preterm infants as part of their standard nutritional protocol in order for the infant to gain weight if BM only failed to produce adequate results. To date, little to no South African studies support or discourage the use of HMF for LBW infants. This study aimed to describe the effect of maternal supplementation compared with breast milk with HMF, or a combination of maternal supplementation and breast milk with HMF, on growth velocity in hospitalised LBW premature infants within the Nelson Mandela Bay health district. The proposed study design followed a longitudinal, observational, descriptive study in a cohort of LBW infants. The study was analytical using quantitative empirical data. Study participants were selected, by using convenience sampling, at Dora Nginza Hospital, Zwide between October 2015 and August 2016 (ethics approval: EC_2016RP27_564). Quantitative data on anthropometric measurements was collected from study participants. Primary care givers provided written informed consent. Registered nurses were trained and performed anthropometrical measurements according to standardised methods. A structured questionnaire was completed by the principal reasarcher as a source of data collection. Numerical data was described using means and standard deviations. Chi squares were used to describe the associations between maternal risk factors and birth weight outcomes. ANOVA was used to determine the relationship between growth velocity and the various supplementation groups. A sample size of 91 LBW preterm infants and mother pairs were entered into this study. The majority of mothers, 64% (n=58) fell in the age category of 20-35 years old. Of the total maternal sample (n=88), 35% (n=31) were classified in the at risk age category, i.e. <20years old and >36years old. Out of the total infant sample (n=91), 65% (n=59) was classified as VLBW, 22% was LBW and 22% (n=20) was ELBW. No statistically significant association was found between infant growth velocity and maternal risk factors. The group receiving BM with HMF had a mean growth velocity of 19.75 g/kg/day (SD=6.45) that was statistically significantly (p<0.05) more than the other groups. The maternal supplementation only group and the maternal supplementation and BM fortification group showed mean growth velocities of 12.26 g/kg/day (SD=5.41) and 12.29 g/kg/day (SD=6.97) respectively. A post hoc test was done between growth velocity in the supplementated groups and the length of hospital stay. These results reveal that the group receiving BM with HMF had a significantly (p<0.05) shorter mean length of hospital stay of 11.29 days (SD=7.02), compared with the group on the combination of maternal supplementation and BM with HMF. In this study, infants receiving HMF with BM showed the highest growth velocity with the shortest hospital stay before discharge. In this group, infants were already receiving an adequate BM intake of 150-180 ml/kg/day prior to participation in the study. This meant that the HMF group consisted of more stable preterm infants compared to the rest of the supplementated groups. However, a large proportion of participants in the maternal supplementation group also showed adequate to good growth velocity. The researcher recommends the implementation of maternal supplementation only, as standard of care for all hospitalised lactating women. Furthermore, timeous addition of HMF to expressed BM is necessary for infants with growth velocities <15 g/kg/day. This may save costs to the hospital as the use of HMF allowed for better weight gain and earlier discharge.
- Full Text:
- Date Issued: 2018
- Authors: Wicomb, Ra-eesa
- Date: 2018
- Subjects: Premature infants -- South Africa -- Nelson Mandela Bay Municipality , Birth weight, Low -- South Africa -- Nelson Mandela Bay Municipality Birth weight -- South Africa -- Nelson Mandela Bay Municipality Infants -- Nutrition Children -- Nutrition -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23327 , vital:30529
- Description: Rationale: Worldwide, hospitals with premature units have one generalised objective, i.e. to achieve postnatal growth and body composition similar to that of a normal foetus of similar gestational age. Optimal nutrition leads to optimal neurodevelopment and breastfeeding (BF) is known as the golden standard for infant nutrition. Human breast milk (BM) has significant value for preterm and term infants and is of special benefit to HIV infected mothers. Maternal supplementation is provided as part of the standard protocol in certain hospitals in the Eastern Cape province to those mothers who breastfeed their low birth weight (LBW) infants after delivery. human milk fortifier (HMF) is a nutritional supplement that is added to expressed breast milk for feeding preterm infants in order to meet their high energy and protein needs and therefore supporting the recommended growth velocity of 10g/kg/day-15g/kg/day. Some hospitals within South Africa provide HMF to preterm infants as part of their standard nutritional protocol in order for the infant to gain weight if BM only failed to produce adequate results. To date, little to no South African studies support or discourage the use of HMF for LBW infants. This study aimed to describe the effect of maternal supplementation compared with breast milk with HMF, or a combination of maternal supplementation and breast milk with HMF, on growth velocity in hospitalised LBW premature infants within the Nelson Mandela Bay health district. The proposed study design followed a longitudinal, observational, descriptive study in a cohort of LBW infants. The study was analytical using quantitative empirical data. Study participants were selected, by using convenience sampling, at Dora Nginza Hospital, Zwide between October 2015 and August 2016 (ethics approval: EC_2016RP27_564). Quantitative data on anthropometric measurements was collected from study participants. Primary care givers provided written informed consent. Registered nurses were trained and performed anthropometrical measurements according to standardised methods. A structured questionnaire was completed by the principal reasarcher as a source of data collection. Numerical data was described using means and standard deviations. Chi squares were used to describe the associations between maternal risk factors and birth weight outcomes. ANOVA was used to determine the relationship between growth velocity and the various supplementation groups. A sample size of 91 LBW preterm infants and mother pairs were entered into this study. The majority of mothers, 64% (n=58) fell in the age category of 20-35 years old. Of the total maternal sample (n=88), 35% (n=31) were classified in the at risk age category, i.e. <20years old and >36years old. Out of the total infant sample (n=91), 65% (n=59) was classified as VLBW, 22% was LBW and 22% (n=20) was ELBW. No statistically significant association was found between infant growth velocity and maternal risk factors. The group receiving BM with HMF had a mean growth velocity of 19.75 g/kg/day (SD=6.45) that was statistically significantly (p<0.05) more than the other groups. The maternal supplementation only group and the maternal supplementation and BM fortification group showed mean growth velocities of 12.26 g/kg/day (SD=5.41) and 12.29 g/kg/day (SD=6.97) respectively. A post hoc test was done between growth velocity in the supplementated groups and the length of hospital stay. These results reveal that the group receiving BM with HMF had a significantly (p<0.05) shorter mean length of hospital stay of 11.29 days (SD=7.02), compared with the group on the combination of maternal supplementation and BM with HMF. In this study, infants receiving HMF with BM showed the highest growth velocity with the shortest hospital stay before discharge. In this group, infants were already receiving an adequate BM intake of 150-180 ml/kg/day prior to participation in the study. This meant that the HMF group consisted of more stable preterm infants compared to the rest of the supplementated groups. However, a large proportion of participants in the maternal supplementation group also showed adequate to good growth velocity. The researcher recommends the implementation of maternal supplementation only, as standard of care for all hospitalised lactating women. Furthermore, timeous addition of HMF to expressed BM is necessary for infants with growth velocities <15 g/kg/day. This may save costs to the hospital as the use of HMF allowed for better weight gain and earlier discharge.
- Full Text:
- Date Issued: 2018
Web-based visualisation techniques for reporting zoonotic outbreaks
- Authors: Ncube, Sinini Paul
- Date: 2012
- Subjects: Zoonoses -- Reporting , Communicable diseases -- Reporting , Communication in medicine , Medical telematics , Internet , Information visualization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4664 , http://hdl.handle.net/10962/d1006672 , Zoonoses -- Reporting , Communicable diseases -- Reporting , Communication in medicine , Medical telematics , Internet , Information visualization
- Description: Zoonotic diseases are diseases that are transmitted from animals or vectors to humans and vice versa. The public together with veterinarian authorities should readily access disease information as it is vital in rapidly controlling resultant zoonotic outbreak threats through improved awareness. Currently, the reporting of disease information in South Africa is predominantly limited to traditional methods of Information Communication Technologies (ICTs) like faxes, monthly newspaper reports, radios, phones and televisions. Although these are effective ways of communication, their disadvantage is that the information that most of them offer can only be accessed at specific times during a crisis. New technologies like the internet have become the most efficient way of distributing information in near-real-time. Many developed countries have used web-based reporting platforms to deliver timely information through temporal and geographic visualisation techniques. There has been an attempt in the use of web-based reporting in South Africa but most of these sites are characterised by heavy text which makes them time consuming to use or maintain. As a result most sites have not been updated or have ceased to exist because of the work load involved. The success of web reporting mechanisms in developed countries offers evidence that web-based reporting systems when appropriately visualised can improve the easy understanding of information and efficiency in the analysis of that data. In this thesis, a web-based reporting prototype was proposed after gathering information from different sources: literature related to disease reporting and the visualisation of infectious diseases; the exploration of the currently deployed web systems; and the investigation of user requirements from relevant parties. The proposed prototype system was then developed using Adobe Flash tools, Java and MySQL languages. A focus group then reviewed the developed system to ascertain that the relevant requirements had been incorporated and to obtain additional ideas about the system. This led to the proposal of a new prototype system that can be used by the authorities concerned as a plan to develop a fully functional disease reporting system for South Africa.
- Full Text:
- Date Issued: 2012
- Authors: Ncube, Sinini Paul
- Date: 2012
- Subjects: Zoonoses -- Reporting , Communicable diseases -- Reporting , Communication in medicine , Medical telematics , Internet , Information visualization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4664 , http://hdl.handle.net/10962/d1006672 , Zoonoses -- Reporting , Communicable diseases -- Reporting , Communication in medicine , Medical telematics , Internet , Information visualization
- Description: Zoonotic diseases are diseases that are transmitted from animals or vectors to humans and vice versa. The public together with veterinarian authorities should readily access disease information as it is vital in rapidly controlling resultant zoonotic outbreak threats through improved awareness. Currently, the reporting of disease information in South Africa is predominantly limited to traditional methods of Information Communication Technologies (ICTs) like faxes, monthly newspaper reports, radios, phones and televisions. Although these are effective ways of communication, their disadvantage is that the information that most of them offer can only be accessed at specific times during a crisis. New technologies like the internet have become the most efficient way of distributing information in near-real-time. Many developed countries have used web-based reporting platforms to deliver timely information through temporal and geographic visualisation techniques. There has been an attempt in the use of web-based reporting in South Africa but most of these sites are characterised by heavy text which makes them time consuming to use or maintain. As a result most sites have not been updated or have ceased to exist because of the work load involved. The success of web reporting mechanisms in developed countries offers evidence that web-based reporting systems when appropriately visualised can improve the easy understanding of information and efficiency in the analysis of that data. In this thesis, a web-based reporting prototype was proposed after gathering information from different sources: literature related to disease reporting and the visualisation of infectious diseases; the exploration of the currently deployed web systems; and the investigation of user requirements from relevant parties. The proposed prototype system was then developed using Adobe Flash tools, Java and MySQL languages. A focus group then reviewed the developed system to ascertain that the relevant requirements had been incorporated and to obtain additional ideas about the system. This led to the proposal of a new prototype system that can be used by the authorities concerned as a plan to develop a fully functional disease reporting system for South Africa.
- Full Text:
- Date Issued: 2012
Web-based M-learning system for ad-hoc learning of mathematical concepts amongst first year students at the University of Namibia
- Authors: Ntinda, Maria Ndapewa
- Date: 2014
- Subjects: Mathematics -- Study and teaching (Higher) -- Namibia , Mathematics -- Technological innovations , Mobile communication systems in education , Teaching -- Aids and devices , Educational innovations , Open source software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4701 , http://hdl.handle.net/10962/d1013174
- Description: In the last decade, there has been an increase in the number of web-enabled mobile devices, offering a new platform that can be targeted for the development of learning applications. Worldwide, developers have taken initiatives in developing mobile learning (M-learning) systems to provide students with access to learning materials regardless of time and location. The purpose of this study was to investigate whether it is viable for first year students enrolled at the University of Namibia (UNAM) to use mobile phones for ad-hoc learning of mathematical concepts. A system, EnjoyMath, aiming to assist students in preparing for tests, examinations, review contents and reinforce knowledge acquired during traditional classroom interactions was designed and implemented. The EnjoyMath system was designed and implemented through the use of the Human Centred Design (HCD) methodology. Two revolutions of the four-step process of the HCD cycle were completed in this study. Due to the distance between UNAM and Rhodes University (where the researcher was based), the researcher could not always work in close relation with the UNAM students. Students from the Extended Study Unit (ESU) at Rhodes University were therefore selected in the first iteration of the project due to their proximity to the researcher and their similar demographics to the first year UNAM students, while the UNAM students were targeted in the second iteration of the study. This thesis presents the outcome of the two pre-intervention studies of the first-year students' perceptions about M-learning conducted at Rhodes University and UNAM. The results of the pre-intervention studies showed that the students are enthusiastic about using an M-learning system, because it would allow them to put in more time to practice their skills whenever and wherever they are. Moreover, the thesis presents the different stages undertaken to develop the EnjoyMath system using Open Source Software (PHP and MySQL). The results of a user study (post-intervention) conducted with participants at UNAM, ascertained the participants' perception of the usability of the EnjoyMath system and are also presented in this thesis. The EnjoyMath system was perceived by the participants to be "passable"; hence an M-learning system could be used to compliment an E-learning system at UNAM.
- Full Text:
- Date Issued: 2014
- Authors: Ntinda, Maria Ndapewa
- Date: 2014
- Subjects: Mathematics -- Study and teaching (Higher) -- Namibia , Mathematics -- Technological innovations , Mobile communication systems in education , Teaching -- Aids and devices , Educational innovations , Open source software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4701 , http://hdl.handle.net/10962/d1013174
- Description: In the last decade, there has been an increase in the number of web-enabled mobile devices, offering a new platform that can be targeted for the development of learning applications. Worldwide, developers have taken initiatives in developing mobile learning (M-learning) systems to provide students with access to learning materials regardless of time and location. The purpose of this study was to investigate whether it is viable for first year students enrolled at the University of Namibia (UNAM) to use mobile phones for ad-hoc learning of mathematical concepts. A system, EnjoyMath, aiming to assist students in preparing for tests, examinations, review contents and reinforce knowledge acquired during traditional classroom interactions was designed and implemented. The EnjoyMath system was designed and implemented through the use of the Human Centred Design (HCD) methodology. Two revolutions of the four-step process of the HCD cycle were completed in this study. Due to the distance between UNAM and Rhodes University (where the researcher was based), the researcher could not always work in close relation with the UNAM students. Students from the Extended Study Unit (ESU) at Rhodes University were therefore selected in the first iteration of the project due to their proximity to the researcher and their similar demographics to the first year UNAM students, while the UNAM students were targeted in the second iteration of the study. This thesis presents the outcome of the two pre-intervention studies of the first-year students' perceptions about M-learning conducted at Rhodes University and UNAM. The results of the pre-intervention studies showed that the students are enthusiastic about using an M-learning system, because it would allow them to put in more time to practice their skills whenever and wherever they are. Moreover, the thesis presents the different stages undertaken to develop the EnjoyMath system using Open Source Software (PHP and MySQL). The results of a user study (post-intervention) conducted with participants at UNAM, ascertained the participants' perception of the usability of the EnjoyMath system and are also presented in this thesis. The EnjoyMath system was perceived by the participants to be "passable"; hence an M-learning system could be used to compliment an E-learning system at UNAM.
- Full Text:
- Date Issued: 2014
Web usage mining of organisational web sites
- Authors: Oosthuizen, Craig Peter
- Date: 2005
- Subjects: Web usage mining -- South Africa , Internet users -- South Africa , Information visualization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9595 , http://hdl.handle.net/10948/399 , Web usage mining -- South Africa , Internet users -- South Africa , Information visualization
- Description: Web Usage Mining (WUM) can be used to determine whether the information architecture of a web site is structured correctly. Existing WUM tools however, do not indicate which web usage mining algorithms are used or provide effective graphical visualisations of the results obtained. WUM techniques can be used to determine typical navigation patterns of the users of organisational web sites. An organisational web site can be described as a site which has a high level of content. The Computer Science & Information Systems (CS&IS) web site at the Nelson Mandela Metropolitan University (NMMU) is an example of such a web site. The process of combining WUM and information visualisation techniques in order to discover useful information about web usage patterns is called visual web mining. The goal of this research is to discuss the development of a WUM model and a prototype, called WebPatterns, which allows the user to effectively visualise web usage patterns of an organisational web site. This will facilitate determining whether the information architecture of the CS&IS web site is structured correctly. The WUM algorithms used in WebPatterns are association rule mining and sequence analysis. The purpose of association rule mining is to discover relationships between different web pages within a web site. Sequence analysis is used to determine the longest time ordered paths that satisfy a user specified minimum frequency. A radial tree layout is used in WebPatterns to visualise the static structure of the organisational web site. The structure of the web site is laid out radially, with the home page in the middle and other pages positioned in circles at various levels around it. Colour and other visual cues are used to show the results of the WUM algorithms. User testing was used to determine the effectiveness and usefulness of WebPatterns for visualising web usage patterns. The results of the user testing clearly show that the participants were highly satisfied with the visual design and information provided by WebPatterns. All the participants also indicated that they would like to use WebPatterns in the future. Analysis of the web usage patterns presented by WebPatterns was used to determine that the information architecture of the CS&IS web site can be restructured to better facilitate information retrieval. Changes to the CS&IS web site web were suggested, included placing embedded hyperlinks on the home page to the frequently accessed sections of the web site.
- Full Text:
- Date Issued: 2005
- Authors: Oosthuizen, Craig Peter
- Date: 2005
- Subjects: Web usage mining -- South Africa , Internet users -- South Africa , Information visualization
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:9595 , http://hdl.handle.net/10948/399 , Web usage mining -- South Africa , Internet users -- South Africa , Information visualization
- Description: Web Usage Mining (WUM) can be used to determine whether the information architecture of a web site is structured correctly. Existing WUM tools however, do not indicate which web usage mining algorithms are used or provide effective graphical visualisations of the results obtained. WUM techniques can be used to determine typical navigation patterns of the users of organisational web sites. An organisational web site can be described as a site which has a high level of content. The Computer Science & Information Systems (CS&IS) web site at the Nelson Mandela Metropolitan University (NMMU) is an example of such a web site. The process of combining WUM and information visualisation techniques in order to discover useful information about web usage patterns is called visual web mining. The goal of this research is to discuss the development of a WUM model and a prototype, called WebPatterns, which allows the user to effectively visualise web usage patterns of an organisational web site. This will facilitate determining whether the information architecture of the CS&IS web site is structured correctly. The WUM algorithms used in WebPatterns are association rule mining and sequence analysis. The purpose of association rule mining is to discover relationships between different web pages within a web site. Sequence analysis is used to determine the longest time ordered paths that satisfy a user specified minimum frequency. A radial tree layout is used in WebPatterns to visualise the static structure of the organisational web site. The structure of the web site is laid out radially, with the home page in the middle and other pages positioned in circles at various levels around it. Colour and other visual cues are used to show the results of the WUM algorithms. User testing was used to determine the effectiveness and usefulness of WebPatterns for visualising web usage patterns. The results of the user testing clearly show that the participants were highly satisfied with the visual design and information provided by WebPatterns. All the participants also indicated that they would like to use WebPatterns in the future. Analysis of the web usage patterns presented by WebPatterns was used to determine that the information architecture of the CS&IS web site can be restructured to better facilitate information retrieval. Changes to the CS&IS web site web were suggested, included placing embedded hyperlinks on the home page to the frequently accessed sections of the web site.
- Full Text:
- Date Issued: 2005
Weather neutral models for short-term electricity demand forecasting
- Authors: Nyulu, Thandekile
- Date: 2013
- Subjects: Electric power consumption -- Forecasting -- Mathematical models , Forecasting -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10578 , http://hdl.handle.net/10948/d1018751
- Description: Energy demand forecasting, and specifically electricity demand forecasting, is a fun-damental feature in both industry and research. Forecasting techniques assist all electricity market participants in accurate planning, selling and purchasing decisions and strategies. Generation and distribution of electricity require appropriate, precise and accurate forecasting methods. Also accurate forecasting models assist producers, researchers and economists to make proper and beneficial future decisions. There are several research papers, which investigate this fundamental aspect and attempt var-ious statistical techniques. Although weather and economic effects have significant influences on electricity demand, in this study they are purposely eliminated from investigation. This research considers calendar-related effects such as months of the year, weekdays and holidays (that is, public holidays, the day before a public holiday, the day after a public holiday, school holidays, university holidays, Easter holidays and major religious holidays) and includes university exams, general election days, day after elections, and municipal elections in the analysis. Regression analysis, cate-gorical regression and auto-regression are used to illustrate the relationships between response variable and explanatory variables. The main objective of the investigation was to build forecasting models based on this calendar data only and to observe how accurate the models can be without taking into account weather effects and economic effects, hence weather neutral models. Weather and economic factors have to be forecasted, and these forecasts are not so accurate and calendar events are known for sure (error-free). Collecting data for weather and economic factors is costly and time consuming, while obtaining calendar data is relatively easy.
- Full Text:
- Date Issued: 2013
- Authors: Nyulu, Thandekile
- Date: 2013
- Subjects: Electric power consumption -- Forecasting -- Mathematical models , Forecasting -- Mathematical models
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10578 , http://hdl.handle.net/10948/d1018751
- Description: Energy demand forecasting, and specifically electricity demand forecasting, is a fun-damental feature in both industry and research. Forecasting techniques assist all electricity market participants in accurate planning, selling and purchasing decisions and strategies. Generation and distribution of electricity require appropriate, precise and accurate forecasting methods. Also accurate forecasting models assist producers, researchers and economists to make proper and beneficial future decisions. There are several research papers, which investigate this fundamental aspect and attempt var-ious statistical techniques. Although weather and economic effects have significant influences on electricity demand, in this study they are purposely eliminated from investigation. This research considers calendar-related effects such as months of the year, weekdays and holidays (that is, public holidays, the day before a public holiday, the day after a public holiday, school holidays, university holidays, Easter holidays and major religious holidays) and includes university exams, general election days, day after elections, and municipal elections in the analysis. Regression analysis, cate-gorical regression and auto-regression are used to illustrate the relationships between response variable and explanatory variables. The main objective of the investigation was to build forecasting models based on this calendar data only and to observe how accurate the models can be without taking into account weather effects and economic effects, hence weather neutral models. Weather and economic factors have to be forecasted, and these forecasts are not so accurate and calendar events are known for sure (error-free). Collecting data for weather and economic factors is costly and time consuming, while obtaining calendar data is relatively easy.
- Full Text:
- Date Issued: 2013
Wavelength-modulation spectroscopy for the evaluation of the photoresponse of solar cells
- Mandanirina, Nambinintsoa Roméoh Hasinjatovo
- Authors: Mandanirina, Nambinintsoa Roméoh Hasinjatovo
- Date: 2016
- Subjects: Gallium arsenide semiconductors , Solar cells , Modulation spectroscopy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7244 , vital:21312
- Description: This study describes the development of a wavelength-modulation spectroscopy technique for the evaluation of solar cell devices. In particular, the technique is used to investigate the sub-bandgap response associated with the incorporation of GaSb quantum rings into the active region of a conventional GaAs p-i-n solar cell. These GaSb/GaAs quantum ring solar cells are a class of third generation cells, with the potential to exceed the Shockley-Queisser efficiency limit of single junction devices. Wavelength-modulation spectroscopy (WMS) techniques involve the modulation of the wavelength of a pseudo-monochromatic light source, with the resulting variation in the measured photocurrent then being a measure of the differential optical response of the solar cell. Although the conventional photocurrent spectrum of a solar cell is a good measure of the optical response characteristics, the differential technique gives supplemental detail related to the absorption spectrum. In addition to the basic WMS setup, we also developed an in situ flux correction module to ensure that a constant excitation intensity is maintained during the wavelength modulation. The excitation source inherently has a spectral dependence that leads to an undesirable contribution to the photocurrent signal. The operation of the flux corrected WMS setup has been demonstrated by photocurrent and photo-capacitance response measurements to obtain the differential quantum efficiency and charging characteristics of the quantum ring solar cells.
- Full Text:
- Date Issued: 2016
- Authors: Mandanirina, Nambinintsoa Roméoh Hasinjatovo
- Date: 2016
- Subjects: Gallium arsenide semiconductors , Solar cells , Modulation spectroscopy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/7244 , vital:21312
- Description: This study describes the development of a wavelength-modulation spectroscopy technique for the evaluation of solar cell devices. In particular, the technique is used to investigate the sub-bandgap response associated with the incorporation of GaSb quantum rings into the active region of a conventional GaAs p-i-n solar cell. These GaSb/GaAs quantum ring solar cells are a class of third generation cells, with the potential to exceed the Shockley-Queisser efficiency limit of single junction devices. Wavelength-modulation spectroscopy (WMS) techniques involve the modulation of the wavelength of a pseudo-monochromatic light source, with the resulting variation in the measured photocurrent then being a measure of the differential optical response of the solar cell. Although the conventional photocurrent spectrum of a solar cell is a good measure of the optical response characteristics, the differential technique gives supplemental detail related to the absorption spectrum. In addition to the basic WMS setup, we also developed an in situ flux correction module to ensure that a constant excitation intensity is maintained during the wavelength modulation. The excitation source inherently has a spectral dependence that leads to an undesirable contribution to the photocurrent signal. The operation of the flux corrected WMS setup has been demonstrated by photocurrent and photo-capacitance response measurements to obtain the differential quantum efficiency and charging characteristics of the quantum ring solar cells.
- Full Text:
- Date Issued: 2016
Water, salt and nutrient budgets of the Swartkops and Sundays river estuaries using the loicz biogeochemical budgeting protocol
- Authors: Potgieter, Matthys Johannes
- Date: 2008
- Subjects: Estuarine oceanography , Groundwater flow -- South Africa -- Swartkops River Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10705 , http://hdl.handle.net/10948/903 , Estuarine oceanography , Groundwater flow -- South Africa -- Swartkops River Estuary
- Description: The Swartkops River and Sundays River Estuaries are different in terms of morphology and the level of human impact. Budget models of DIP and DIN were constructed for each estuary at different riverine flow rates, using the Land-Ocean Interactions in the Coastal Zone (LOICZ) protocol. Nutrient dynamics in the estuaries were investigated using nutrient data and the results of the models. The Swartkops River Estuary acted as a sink of DIP and DIN, while being net heterotrophic. The Sundays River Estuary acted as a source of DIP and DIN, while being net autotrophic. Both systems were net denitrifying. The Swartkops River Estuary shows greater anthropogenic impacts in terms of nutrient loads than the Sundays River Estuary. A shift in nutrient concentration trends and system properties occurred between conditions of low and high riverine flow rates. The Swartkops River and Sundays River Estuaries were shown to be ‘outwellers’ of DIN and DIP, while having an important influence on the ratio of DIN:DIP exported to the adjacent ocean. Comparisons with other estuaries suggested that riverine flow into estuaries in the Eastern Cape region may display natural DIN:DIP ratios which are lower than the global average for “pristine” systems. Such ratios would be decreased further by increased water extraction for human activities.
- Full Text:
- Date Issued: 2008
- Authors: Potgieter, Matthys Johannes
- Date: 2008
- Subjects: Estuarine oceanography , Groundwater flow -- South Africa -- Swartkops River Estuary
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10705 , http://hdl.handle.net/10948/903 , Estuarine oceanography , Groundwater flow -- South Africa -- Swartkops River Estuary
- Description: The Swartkops River and Sundays River Estuaries are different in terms of morphology and the level of human impact. Budget models of DIP and DIN were constructed for each estuary at different riverine flow rates, using the Land-Ocean Interactions in the Coastal Zone (LOICZ) protocol. Nutrient dynamics in the estuaries were investigated using nutrient data and the results of the models. The Swartkops River Estuary acted as a sink of DIP and DIN, while being net heterotrophic. The Sundays River Estuary acted as a source of DIP and DIN, while being net autotrophic. Both systems were net denitrifying. The Swartkops River Estuary shows greater anthropogenic impacts in terms of nutrient loads than the Sundays River Estuary. A shift in nutrient concentration trends and system properties occurred between conditions of low and high riverine flow rates. The Swartkops River and Sundays River Estuaries were shown to be ‘outwellers’ of DIN and DIP, while having an important influence on the ratio of DIN:DIP exported to the adjacent ocean. Comparisons with other estuaries suggested that riverine flow into estuaries in the Eastern Cape region may display natural DIN:DIP ratios which are lower than the global average for “pristine” systems. Such ratios would be decreased further by increased water extraction for human activities.
- Full Text:
- Date Issued: 2008
Water requirements and distribution of Ammophila arenaria and Scaevola plumieri on South African coastal dunes
- Authors: Peter, Craig Ingram
- Date: 2000
- Subjects: Scaevola plumieri , Sand dune plants , Sand dune planting , Plants -- Transpiration , Sandworts , Plant-water relationships , Evapotranspiration , Plants, Effect of heat on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4219 , http://hdl.handle.net/10962/d1003788 , Scaevola plumieri , Sand dune plants , Sand dune planting , Plants -- Transpiration , Sandworts , Plant-water relationships , Evapotranspiration , Plants, Effect of heat on
- Description: Phenomenological models are presented which predicts transpiration rates (E) of individual leaves of Scaevola plumieri, an indigenous dune pioneer, and Ammophila arenaria, an exotic grass species introduced to stabilise mobile sand. In both cases E is predictably related to atmospheric vapour pressure deficit (VPD). VPD is calculated from measurements of ambient temperature and humidity, hence, where these two environmental variables are known, E can be calculated. Possible physiological reasons for the relationships of E to VPD in both species are discussed. Scaling from measurements of E at the leaf level to the canopy level is achieved by summing the leaf area of the canopy in question. E is predicted for the entire canopy leaf area by extrapolation to this larger leaf area. Predicted transpiration rates of individual shoot within the canopy were tested gravimetrically and shown to be accurate in the case of S. plumieri, but less so in the case of A. arenaria. Using this model, the amount of water used by a known area of sand dune is shown to be less than the rainfall input in the case of S. plumieri in wet and dry years. The water use of A. arenaria exceeds rainfall in the low-rainfall year of 1995, while in 1998 rainfall input is slightly higher than water extraction by the plants. Using a geographic information system (GIS), regional maps (surfaces) of transpiration were calculated from surfaces of mean monthly temperature and mean monthly relative humidity. Monthly surfaces of transpiration were subtracted from the monthly median rainfall to produce a surface of mean monthly water deficit. Areas of water surpluses along the coast correspond with the recorded distribution of both species in the seasons that the plants are most actively growing and reproducing. This suggests that unfavourable water availability during these two species growth periods limit their distributions along the coast. In addition to unfavourable water deficits, additional climatic variables that may be important in limiting the distribution of these two species were investigated using a discriminant function analysis.
- Full Text:
- Date Issued: 2000
- Authors: Peter, Craig Ingram
- Date: 2000
- Subjects: Scaevola plumieri , Sand dune plants , Sand dune planting , Plants -- Transpiration , Sandworts , Plant-water relationships , Evapotranspiration , Plants, Effect of heat on
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4219 , http://hdl.handle.net/10962/d1003788 , Scaevola plumieri , Sand dune plants , Sand dune planting , Plants -- Transpiration , Sandworts , Plant-water relationships , Evapotranspiration , Plants, Effect of heat on
- Description: Phenomenological models are presented which predicts transpiration rates (E) of individual leaves of Scaevola plumieri, an indigenous dune pioneer, and Ammophila arenaria, an exotic grass species introduced to stabilise mobile sand. In both cases E is predictably related to atmospheric vapour pressure deficit (VPD). VPD is calculated from measurements of ambient temperature and humidity, hence, where these two environmental variables are known, E can be calculated. Possible physiological reasons for the relationships of E to VPD in both species are discussed. Scaling from measurements of E at the leaf level to the canopy level is achieved by summing the leaf area of the canopy in question. E is predicted for the entire canopy leaf area by extrapolation to this larger leaf area. Predicted transpiration rates of individual shoot within the canopy were tested gravimetrically and shown to be accurate in the case of S. plumieri, but less so in the case of A. arenaria. Using this model, the amount of water used by a known area of sand dune is shown to be less than the rainfall input in the case of S. plumieri in wet and dry years. The water use of A. arenaria exceeds rainfall in the low-rainfall year of 1995, while in 1998 rainfall input is slightly higher than water extraction by the plants. Using a geographic information system (GIS), regional maps (surfaces) of transpiration were calculated from surfaces of mean monthly temperature and mean monthly relative humidity. Monthly surfaces of transpiration were subtracted from the monthly median rainfall to produce a surface of mean monthly water deficit. Areas of water surpluses along the coast correspond with the recorded distribution of both species in the seasons that the plants are most actively growing and reproducing. This suggests that unfavourable water availability during these two species growth periods limit their distributions along the coast. In addition to unfavourable water deficits, additional climatic variables that may be important in limiting the distribution of these two species were investigated using a discriminant function analysis.
- Full Text:
- Date Issued: 2000
Water quality, biomass and extracellular polymeric substances in an integrated algae pond system
- Authors: Jimoh, Taobat Adekilekun
- Date: 2018
- Subjects: Water -- Purification , Sewage -- Purification -- Anaerobic treatment , Sewage lagoons , Sewage disposal plants , ASPAM model (Acid mine drainage) , Integrated algae pond systems (IAPS)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57307 , vital:26871
- Description: Integrated algae pond systems (IAPS) combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Although, IAPS as a technology process offers many advantages including efficient and simultaneous N and P removal, no requirement for additional chemicals, O2 generation, CO2 mitigation, and a biomass with potential for valorization, a lack of technological advancement and the need for large land area, has limited the reach of this technology at industrial scale. In mitigation, peroxonation was introduced as a tertiary treatment unit and its effect on COD and TSS of IAPS treated water investigated. An effort was made to characterize the soluble but persistent COD in IAPS treated water and, productivity of the HRAOP mixed liquor was investigated to gain insight into the potential use of this biomass. Results show that peroxone treatment effectively reduced COD, TSS, and nutrient load of IAPS water without any significant impact on land area requirement. Indeed, summary data describing the effect of peroxone on quality of IAPS-treated water confirmed that it complies with the general limit values for either irrigation or discharge into a water resource that is not a listed water resource for volumes up to 2 ML of treated wastewater on any given day. Extraction followed by FT-IR spectroscopy was used to confirm albeit tentatively, the identity of the soluble but persistent COD in IAPS treated water as MaB-floc EPS. Results show that MaB-flocs from HRAOPs are assemblages of microorganisms produced as discrete aggregates as a result of microbial EPS production. A relationship between photosynthesis and EPS production was established by quantification of the EPS following exposure of MaB-flocs to either continuous light or darkness. Several novel strains of bacteria were isolated from HRAOP mixed liquor and 16S ribosomal genomic sequence analysis resulted in the molecular characterization of Planococcus maitriensis strain ECCN 45b. This is the first report of Planococcus maitriensis from a wastewater treatment process. Productivity and change in MaB-flocs concentration, measured as mixed liquor suspended solids (MLSS) between morning and evening were monitored and revealed that MLSS is composed of microalgae and bacteria but not fungi. Concentration varied from 77 mg L-1 in September (winter) to 285 mg L-1 in November (spring); pond productivity increased from 5.8 g m-2 d-1 (winter) to 21.5 g m-2 d-1 (spring); and, irrespective of MLSS concentration in late afternoon, approximately 39% was lost overnight, which presumably occurred due to passive removal by the algae settling pond. The outcomes of this research are discussed in terms of the quality of treated water, and the further development of IAPS as a platform technology for establishing a biorefinery within the wastewater treatment sector.
- Full Text:
- Date Issued: 2018
- Authors: Jimoh, Taobat Adekilekun
- Date: 2018
- Subjects: Water -- Purification , Sewage -- Purification -- Anaerobic treatment , Sewage lagoons , Sewage disposal plants , ASPAM model (Acid mine drainage) , Integrated algae pond systems (IAPS)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/57307 , vital:26871
- Description: Integrated algae pond systems (IAPS) combine the use of anaerobic and aerobic bioprocesses to effect wastewater treatment. Although, IAPS as a technology process offers many advantages including efficient and simultaneous N and P removal, no requirement for additional chemicals, O2 generation, CO2 mitigation, and a biomass with potential for valorization, a lack of technological advancement and the need for large land area, has limited the reach of this technology at industrial scale. In mitigation, peroxonation was introduced as a tertiary treatment unit and its effect on COD and TSS of IAPS treated water investigated. An effort was made to characterize the soluble but persistent COD in IAPS treated water and, productivity of the HRAOP mixed liquor was investigated to gain insight into the potential use of this biomass. Results show that peroxone treatment effectively reduced COD, TSS, and nutrient load of IAPS water without any significant impact on land area requirement. Indeed, summary data describing the effect of peroxone on quality of IAPS-treated water confirmed that it complies with the general limit values for either irrigation or discharge into a water resource that is not a listed water resource for volumes up to 2 ML of treated wastewater on any given day. Extraction followed by FT-IR spectroscopy was used to confirm albeit tentatively, the identity of the soluble but persistent COD in IAPS treated water as MaB-floc EPS. Results show that MaB-flocs from HRAOPs are assemblages of microorganisms produced as discrete aggregates as a result of microbial EPS production. A relationship between photosynthesis and EPS production was established by quantification of the EPS following exposure of MaB-flocs to either continuous light or darkness. Several novel strains of bacteria were isolated from HRAOP mixed liquor and 16S ribosomal genomic sequence analysis resulted in the molecular characterization of Planococcus maitriensis strain ECCN 45b. This is the first report of Planococcus maitriensis from a wastewater treatment process. Productivity and change in MaB-flocs concentration, measured as mixed liquor suspended solids (MLSS) between morning and evening were monitored and revealed that MLSS is composed of microalgae and bacteria but not fungi. Concentration varied from 77 mg L-1 in September (winter) to 285 mg L-1 in November (spring); pond productivity increased from 5.8 g m-2 d-1 (winter) to 21.5 g m-2 d-1 (spring); and, irrespective of MLSS concentration in late afternoon, approximately 39% was lost overnight, which presumably occurred due to passive removal by the algae settling pond. The outcomes of this research are discussed in terms of the quality of treated water, and the further development of IAPS as a platform technology for establishing a biorefinery within the wastewater treatment sector.
- Full Text:
- Date Issued: 2018