The consumption and use of wild foods by children across a deforestation gradient in Zomba District, Malawi
- Authors: Maseko, Heather Nonhlanhla
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3212 , vital:20392
- Description: Despite consensus on their significant nutritional value, wild foods are continually excluded from both food security statistics and economic values of natural resources. Though largely unexplored, there is evidence on the use of wild foods by children to supplement their diets and as a source of income. Children have knowledge on the gathering and hunting of selected wild food species and sources thereof. Wetlands, agro-ecosystems, natural forests, human landscapes and river systems remain important sources of wild food resources. The provision of and access to these resources are significantly affected by the interference and disruption to natural ecosystems. In Malawi, interference has been largely due to deforestation and land use change caused by an interplay of pressures from population growth for development and agricultural expansion. Against this background, the implications of deforestation and vegetation cover on the availability of wild foods and their access and use by children is largely unexplored. Through a comprehensive analysis of data collected from 150 children and 50 elderly men and women, the integration of Participatory Rural Appraisal (PRA) exercises and Geographic Information System (GIS), in the four sites of Mpheta, Mtuluma, Kasonga and Makombe in Zomba district, wild foods availability was established and their contribution to the nutritional status of children and households’ food security assessed. Study sites were identified along the deforestation gradient of Lake Chilwa, Zomba Mountain and Shire River basin with an additional focus on varying landscapes. One hundred and twenty species of wild foods were identified with greatest availability in areas of high vegetation cover and the lowest in areas of low vegetation cover, but with meaningful differences per wild food category. There was considerable reduction in the availability of wild foods with increasing deforestation; mainly wild game and fruits species and, in turn, decreased access of these by children. Nevertheless, small game, insects, other wild fruits and wild vegetables thrive well in agro-ecosystems and therefore were minimally affected by deforestation but largely by management practices of those systems and can be possibly improved through the promotion of agro-ecological farming systems. The research reveals that wild foods form an important component of the starch based diets of households from agricultural communities in the various landscapes. Besides securing the household’s food base, all children largely supplemented their diets with wild foods but with increased dependence by children from poorer households who are highly vulnerable to food insecurity. Access and use of wild foods was largely dependent on children’s knowledge, perceptions of the wild food and ease of access, with considerable variations due to gender and socio-cultural norms. Besides contributing to the nutritional status and food security, commercialisation of wild foods was common among children, hence providing them with an alternative livelihood strategy and in some cases only viable source of income.
- Full Text:
- Authors: Maseko, Heather Nonhlanhla
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3212 , vital:20392
- Description: Despite consensus on their significant nutritional value, wild foods are continually excluded from both food security statistics and economic values of natural resources. Though largely unexplored, there is evidence on the use of wild foods by children to supplement their diets and as a source of income. Children have knowledge on the gathering and hunting of selected wild food species and sources thereof. Wetlands, agro-ecosystems, natural forests, human landscapes and river systems remain important sources of wild food resources. The provision of and access to these resources are significantly affected by the interference and disruption to natural ecosystems. In Malawi, interference has been largely due to deforestation and land use change caused by an interplay of pressures from population growth for development and agricultural expansion. Against this background, the implications of deforestation and vegetation cover on the availability of wild foods and their access and use by children is largely unexplored. Through a comprehensive analysis of data collected from 150 children and 50 elderly men and women, the integration of Participatory Rural Appraisal (PRA) exercises and Geographic Information System (GIS), in the four sites of Mpheta, Mtuluma, Kasonga and Makombe in Zomba district, wild foods availability was established and their contribution to the nutritional status of children and households’ food security assessed. Study sites were identified along the deforestation gradient of Lake Chilwa, Zomba Mountain and Shire River basin with an additional focus on varying landscapes. One hundred and twenty species of wild foods were identified with greatest availability in areas of high vegetation cover and the lowest in areas of low vegetation cover, but with meaningful differences per wild food category. There was considerable reduction in the availability of wild foods with increasing deforestation; mainly wild game and fruits species and, in turn, decreased access of these by children. Nevertheless, small game, insects, other wild fruits and wild vegetables thrive well in agro-ecosystems and therefore were minimally affected by deforestation but largely by management practices of those systems and can be possibly improved through the promotion of agro-ecological farming systems. The research reveals that wild foods form an important component of the starch based diets of households from agricultural communities in the various landscapes. Besides securing the household’s food base, all children largely supplemented their diets with wild foods but with increased dependence by children from poorer households who are highly vulnerable to food insecurity. Access and use of wild foods was largely dependent on children’s knowledge, perceptions of the wild food and ease of access, with considerable variations due to gender and socio-cultural norms. Besides contributing to the nutritional status and food security, commercialisation of wild foods was common among children, hence providing them with an alternative livelihood strategy and in some cases only viable source of income.
- Full Text:
The design, development and evaluation of cross-platform mobile applications and services supporting social accountability monitoring
- Authors: Reynell, Edward Robin
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3652 , vital:20533
- Description: Local government processes require meaningful and effective participation from both citizens and their governments in order to remain truly democratic. This project investigates the use of mobile phones as a tool for supporting this participation. MobiSAM, a system which aims to enhance the Social Accountability Monitoring (SAM) methodology at local government level, has been designed and implemented. The research presented in this thesis examines tools and techniques for the development of cross-platform client applications, allowing access to the MobiSAM service, across heterogeneous mobile platforms, handsets and interaction styles. Particular attention is paid to providing an easily navigated user interface (UI), as well as offering clear and concise visualisation capabilities. Depending on the host device, interactivity is also included within these visualisations, potentially helping provide further insight into the visualised data. Guided by the results obtained from a comprehensive baseline study of the Grahamstown area, steps are taken in an attempt to lower the barrier of entry to using the MobiSAM service, potentially maximising its market reach. These include extending client application support to all identified mobile platforms (including feature phones); providing multi-language UIs (in English, isiXhosa and Afrikaans); as well as ensuring client application data usage is kept to a minimum. The particular strengths of a given device are also leveraged, such as its camera capabilities and built-in Global Positioning System (GPS) module, potentially allowing for more effective engagement with local municipalities. Additionally, a Short Message Service (SMS) gateway is developed, allowing all Global System for Mobile Communications (GSM) compatible handsets access to the MobiSAM service via traditional SMS. Following an iterative, user-centred design process, a thorough evaluation of the client application is also performed, in an attempt to gather feedback relating to the navigation and visualisation capabilities. The results of which are used to further refine its design. A comparative usability evaluation using two different versions of the cross-platform client application is also undertaken, highlighting the perceived memorability, learnabilitv and satisfaction of each. Results from the evaluation reveals which version of the client application is to be deployed during future pilot studies.
- Full Text:
- Authors: Reynell, Edward Robin
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3652 , vital:20533
- Description: Local government processes require meaningful and effective participation from both citizens and their governments in order to remain truly democratic. This project investigates the use of mobile phones as a tool for supporting this participation. MobiSAM, a system which aims to enhance the Social Accountability Monitoring (SAM) methodology at local government level, has been designed and implemented. The research presented in this thesis examines tools and techniques for the development of cross-platform client applications, allowing access to the MobiSAM service, across heterogeneous mobile platforms, handsets and interaction styles. Particular attention is paid to providing an easily navigated user interface (UI), as well as offering clear and concise visualisation capabilities. Depending on the host device, interactivity is also included within these visualisations, potentially helping provide further insight into the visualised data. Guided by the results obtained from a comprehensive baseline study of the Grahamstown area, steps are taken in an attempt to lower the barrier of entry to using the MobiSAM service, potentially maximising its market reach. These include extending client application support to all identified mobile platforms (including feature phones); providing multi-language UIs (in English, isiXhosa and Afrikaans); as well as ensuring client application data usage is kept to a minimum. The particular strengths of a given device are also leveraged, such as its camera capabilities and built-in Global Positioning System (GPS) module, potentially allowing for more effective engagement with local municipalities. Additionally, a Short Message Service (SMS) gateway is developed, allowing all Global System for Mobile Communications (GSM) compatible handsets access to the MobiSAM service via traditional SMS. Following an iterative, user-centred design process, a thorough evaluation of the client application is also performed, in an attempt to gather feedback relating to the navigation and visualisation capabilities. The results of which are used to further refine its design. A comparative usability evaluation using two different versions of the cross-platform client application is also undertaken, highlighting the perceived memorability, learnabilitv and satisfaction of each. Results from the evaluation reveals which version of the client application is to be deployed during future pilot studies.
- Full Text:
The development of captopril pellets using the principles of quality by design
- Veerubhotla, Hari Mani Krishna
- Authors: Veerubhotla, Hari Mani Krishna
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64769 , vital:28599
- Description: Expected release date-May 2018
- Full Text:
- Authors: Veerubhotla, Hari Mani Krishna
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64769 , vital:28599
- Description: Expected release date-May 2018
- Full Text:
The effect of novel thiazole-derived small molecules on the neuronal differentiation of human neuroblastoma SH-SY5Y cells
- Authors: Joos-Vandewalle, Julia
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64507 , vital:28554
- Description: Expected release date-April 2020
- Full Text:
- Authors: Joos-Vandewalle, Julia
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/64507 , vital:28554
- Description: Expected release date-April 2020
- Full Text:
The efficacy of a community based eccentric hamstring strengthening program in peri-urban Black South African soccer players
- Authors: Ryan, Bennett
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3573 , vital:20526
- Description: Introduction: Hamstring injury prevalence in soccer remains a major concern. Research in this context has focused on Caucasian populations with little attention given to other ethnic groups. The compatibility and applicability of such research to the South African context, particularly at an amateur level, may be minimal due to fundamental differences in physical characteristics, as well as complexities with regards to implementation. The aim of this investigation was therefore twofold. 1) Identify the lower extremity strength and performance profile of Peri-urban Amateur South African Players, and 2) Assess the efficacy of a community based intervention through the use of the Nordic Hamstring Exercise. Methods: 19 Black male Eastern Cape amateur players participated in a 12 week randomly controlled trial (9 = Control, 10 = Intervention). All participants completed regular training, while the intervention group, in addition, performed the Nordic Hamstring exercise post warm up. The incremental program design was taken from Mjolsnes et al. (2004), with a progressive increase in both sets and repetitions. Compliance was defined as completion of the required exercises for that session. Isokinetic strength evaluations (at 60°.s-1 and 180°.s-1) including assessment of peak torque and total work, as well as performance measures of countermovement and squat jump, were completed pre and post intervention, with the profile of the Peri-urban player the combined responses of both groups at baseline. Additionally, both the functional ratio (Eccentric Hamstrings/Concentric Quadriceps) and eccentric utilization ratio (Countermovement Jump/Squat Jump) were calculated. Results: Concentric quadriceps peak torque at baseline reported values of 195 (±22) Nm and 141 (±21) Nm at 60°.s-1 and 180°.s-1. Values of 162 (±21) Nm were observed for peak torque of the eccentric hamstrings at 60°.s-1, while 157 (±18) Nm was indicated at 180°.s-1. Mean functional ratio responses were observed as 0.83 (±0.11) and 1.12 (±0.16) for 60°.s-1 and 180°.s-1 respectively. Additionally, the eccentric utilization ratio responses were recorded as 1.04 (±0.08). Regarding the intervention, concentric quadriceps total work of the dominant limb significantly improved over the time course of experimentation within the intervention group. Other quadriceps variables, concentric hamstrings, squat jump capability and performance measures all reported no significant changes (p>0.05) over the course of assessment when compared to the control. Eccentric hamstrings peak torque observed significant improvements (p<0.05) of between 5.72 and 12.82 % within the intervention group, while the countermovement jump indicated a significant 15.59 % increase (p<0.05). Additionally, the functional ratio and the eccentric utilization ratio both indicated no significant changes (p>0.05), with a 2.48-7.66 % and 5.33 % improvement noted following completion of assessment. Conclusion: Isokinetic responses at baseline observed decreased quadriceps strength, and increased hamstring strength when compared to both amateur and professional populations examined in previous studies, for both isokinetic testing speeds. Additionally, performance measures indicated similar responses to other amateur populations. Regarding the intervention, significant improvements in eccentric hamstring peak torque and countermovement jump indicate the partial success of the present intervention. Additionally, while the functional ratio and eccentric utilization ratio reported no significant changes, improvements were noted within the intervention group while the control noted no change. The Nordic hamstring lower therefore resulted in strength improvements within the eccentric hamstrings, reported as a significant factor for injury risk, however, such changes were not sufficient to significantly impact the functional ratio. It can be concluded that community based programs within South Africa have the potential to be effective; however, there are many barriers to implementation, including, language, ethnic and cultural differences, while a lack of resources and infrastructure play a significant role in a lack of development. More research of this nature is required to provide scientific support for structures and guidelines for the peri-urban community based South African player, to ensure the efficacy of internationally successful interventions such as the Nordic exercise.
- Full Text:
- Authors: Ryan, Bennett
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3573 , vital:20526
- Description: Introduction: Hamstring injury prevalence in soccer remains a major concern. Research in this context has focused on Caucasian populations with little attention given to other ethnic groups. The compatibility and applicability of such research to the South African context, particularly at an amateur level, may be minimal due to fundamental differences in physical characteristics, as well as complexities with regards to implementation. The aim of this investigation was therefore twofold. 1) Identify the lower extremity strength and performance profile of Peri-urban Amateur South African Players, and 2) Assess the efficacy of a community based intervention through the use of the Nordic Hamstring Exercise. Methods: 19 Black male Eastern Cape amateur players participated in a 12 week randomly controlled trial (9 = Control, 10 = Intervention). All participants completed regular training, while the intervention group, in addition, performed the Nordic Hamstring exercise post warm up. The incremental program design was taken from Mjolsnes et al. (2004), with a progressive increase in both sets and repetitions. Compliance was defined as completion of the required exercises for that session. Isokinetic strength evaluations (at 60°.s-1 and 180°.s-1) including assessment of peak torque and total work, as well as performance measures of countermovement and squat jump, were completed pre and post intervention, with the profile of the Peri-urban player the combined responses of both groups at baseline. Additionally, both the functional ratio (Eccentric Hamstrings/Concentric Quadriceps) and eccentric utilization ratio (Countermovement Jump/Squat Jump) were calculated. Results: Concentric quadriceps peak torque at baseline reported values of 195 (±22) Nm and 141 (±21) Nm at 60°.s-1 and 180°.s-1. Values of 162 (±21) Nm were observed for peak torque of the eccentric hamstrings at 60°.s-1, while 157 (±18) Nm was indicated at 180°.s-1. Mean functional ratio responses were observed as 0.83 (±0.11) and 1.12 (±0.16) for 60°.s-1 and 180°.s-1 respectively. Additionally, the eccentric utilization ratio responses were recorded as 1.04 (±0.08). Regarding the intervention, concentric quadriceps total work of the dominant limb significantly improved over the time course of experimentation within the intervention group. Other quadriceps variables, concentric hamstrings, squat jump capability and performance measures all reported no significant changes (p>0.05) over the course of assessment when compared to the control. Eccentric hamstrings peak torque observed significant improvements (p<0.05) of between 5.72 and 12.82 % within the intervention group, while the countermovement jump indicated a significant 15.59 % increase (p<0.05). Additionally, the functional ratio and the eccentric utilization ratio both indicated no significant changes (p>0.05), with a 2.48-7.66 % and 5.33 % improvement noted following completion of assessment. Conclusion: Isokinetic responses at baseline observed decreased quadriceps strength, and increased hamstring strength when compared to both amateur and professional populations examined in previous studies, for both isokinetic testing speeds. Additionally, performance measures indicated similar responses to other amateur populations. Regarding the intervention, significant improvements in eccentric hamstring peak torque and countermovement jump indicate the partial success of the present intervention. Additionally, while the functional ratio and eccentric utilization ratio reported no significant changes, improvements were noted within the intervention group while the control noted no change. The Nordic hamstring lower therefore resulted in strength improvements within the eccentric hamstrings, reported as a significant factor for injury risk, however, such changes were not sufficient to significantly impact the functional ratio. It can be concluded that community based programs within South Africa have the potential to be effective; however, there are many barriers to implementation, including, language, ethnic and cultural differences, while a lack of resources and infrastructure play a significant role in a lack of development. More research of this nature is required to provide scientific support for structures and guidelines for the peri-urban community based South African player, to ensure the efficacy of internationally successful interventions such as the Nordic exercise.
- Full Text:
The EPR paradox: back from the future
- Authors: Bryan, Kate Louise Halse
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2881 , vital:20338
- Description: The Einstein-Podolsky-Rosen (EPR) thought experiment produced a problem regarding the interpretation of quantum mechanics provided for entangled systems. Although the thought experiment was reformulated mathematically in Bell's Theorem, the conclusion regarding entanglement correlations is still debated today. In an attempt to provide an explanation of how entangled systems maintain their correlations, this thesis investigates the theory of post-state teleportation as a possible interpretation of how information moves between entangled systems without resorting to nonlocal action. Post-state teleportation describes a method of communicating to the past via a quantum information channel. The resulting picture of the EPR thought experiment relied on information propagating backward from a final boundary condition to ensure all correlations were maintained. Similarities were found between this resolution of the EPR paradox and the final state solution to the black hole information paradox and the closely related firewall problem. The latter refers to an apparent conflict between unitary evaporation of a black hole and the strong subadditivity condition. The use of observer complementarity allows this solution of the black hole problem to be shown to be the same as a seemingly different solution known as “ER=EPR", where ‘ER’ refers to an Einstein-Rosen bridge or wormhole.
- Full Text:
- Authors: Bryan, Kate Louise Halse
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2881 , vital:20338
- Description: The Einstein-Podolsky-Rosen (EPR) thought experiment produced a problem regarding the interpretation of quantum mechanics provided for entangled systems. Although the thought experiment was reformulated mathematically in Bell's Theorem, the conclusion regarding entanglement correlations is still debated today. In an attempt to provide an explanation of how entangled systems maintain their correlations, this thesis investigates the theory of post-state teleportation as a possible interpretation of how information moves between entangled systems without resorting to nonlocal action. Post-state teleportation describes a method of communicating to the past via a quantum information channel. The resulting picture of the EPR thought experiment relied on information propagating backward from a final boundary condition to ensure all correlations were maintained. Similarities were found between this resolution of the EPR paradox and the final state solution to the black hole information paradox and the closely related firewall problem. The latter refers to an apparent conflict between unitary evaporation of a black hole and the strong subadditivity condition. The use of observer complementarity allows this solution of the black hole problem to be shown to be the same as a seemingly different solution known as “ER=EPR", where ‘ER’ refers to an Einstein-Rosen bridge or wormhole.
- Full Text:
The impact of three different footwear conditions on individual biomechanical, physiological and perceptual responses during running.
- Authors: McDougall, Justin John
- Date: 2016
- Subjects: Running -- Physiological aspects , Running shoes -- Physiological aspects , Running -- Health aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5177 , http://hdl.handle.net/10962/d1019988
- Description: Background: Despite the introduction of running footwear in the 1970’s, running injury rates continue to be unacceptably high. The subsequent revival of barefoot running and the introduction of minimalist footwear occurred, in an attempt to reduce injury rates and increase performance. There is much contention in the literature around the effectiveness of these footwear conditions. Furthermore individual responses have recently been proposed to provide more accurate and reflective conclusions than the use of mean data. Objectives: Twofold: a) to compare the biomechanical, physiological and perceptual responses between the shod, minimalist and barefoot footwear conditions and b) to assess and compare individual responses under these footwear conditions. Methods: 26 well-trained, male, habitually shod endurance runners, aged between 18 - 30 years completed three experimental sessions on an indoor runway and motorized treadmill. Each session was completed in either the shod, minimalist or barefoot condition, running at 15km.h-1. Variables assessed included stride rate, stride length, impact peak, vertical impact and average loading rate and strike time (biomechanical); heart rate, oxygen consumption and electromyography (physiological); and rating of perceived exertion and body discomfort (perceptual). Results: Biomechanics – Stride rate and stride length showed a significant (p<0.001) increase and decrease respectively when running in the minimalist or barefoot conditions versus shod. Running barefoot versus the minimalist and shod conditions resulted in a significantly (p<0.001) greater vertical impact loading rate. Strike time was significantly (p=0.008) reduced running in the minimalist and barefoot conditions versus shod. Physiology – Running barefoot versus shod resulted in a significantly (p=0.02) reduced heart rate and Tibialis Anterior activity (p=0.005). There was a large variability in individual responses for many variables, with responders and non-responders seen. Conclusion: The study suggests that there are significant differences between all three forms of running for some variables. It was further noted that there is support for the proposal that individual responses are highly variable and should be analysed accordingly
- Full Text:
- Authors: McDougall, Justin John
- Date: 2016
- Subjects: Running -- Physiological aspects , Running shoes -- Physiological aspects , Running -- Health aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5177 , http://hdl.handle.net/10962/d1019988
- Description: Background: Despite the introduction of running footwear in the 1970’s, running injury rates continue to be unacceptably high. The subsequent revival of barefoot running and the introduction of minimalist footwear occurred, in an attempt to reduce injury rates and increase performance. There is much contention in the literature around the effectiveness of these footwear conditions. Furthermore individual responses have recently been proposed to provide more accurate and reflective conclusions than the use of mean data. Objectives: Twofold: a) to compare the biomechanical, physiological and perceptual responses between the shod, minimalist and barefoot footwear conditions and b) to assess and compare individual responses under these footwear conditions. Methods: 26 well-trained, male, habitually shod endurance runners, aged between 18 - 30 years completed three experimental sessions on an indoor runway and motorized treadmill. Each session was completed in either the shod, minimalist or barefoot condition, running at 15km.h-1. Variables assessed included stride rate, stride length, impact peak, vertical impact and average loading rate and strike time (biomechanical); heart rate, oxygen consumption and electromyography (physiological); and rating of perceived exertion and body discomfort (perceptual). Results: Biomechanics – Stride rate and stride length showed a significant (p<0.001) increase and decrease respectively when running in the minimalist or barefoot conditions versus shod. Running barefoot versus the minimalist and shod conditions resulted in a significantly (p<0.001) greater vertical impact loading rate. Strike time was significantly (p=0.008) reduced running in the minimalist and barefoot conditions versus shod. Physiology – Running barefoot versus shod resulted in a significantly (p=0.02) reduced heart rate and Tibialis Anterior activity (p=0.005). There was a large variability in individual responses for many variables, with responders and non-responders seen. Conclusion: The study suggests that there are significant differences between all three forms of running for some variables. It was further noted that there is support for the proposal that individual responses are highly variable and should be analysed accordingly
- Full Text:
The phytogeography of Southern Mistbelt Forests of the Eastern Cape, South Africa
- Authors: Matiwane, Aviwe
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3224 , vital:20393
- Description: In the Eastern Cape, a moisture gradient (from west to east) exists along the Escarpment where patches of Southern Mistbelt Forests (SMF) occur. There is a notable profusion of plants in these forests, but the factors that drive plant species composition and abundance in these patches is poorly understood and such knowledge is critical if we are to address or mitigate the problems imposed by global change. Many of our ideas on plant community assembly are based on the premise that species differ in their environmental requirements for successful regeneration, especially when young. The aims of this study were to document the floristic diversity of poorly known patches of Southern Mistbelt Forests in the Eastern Cape and identify the environmental factors that influence plant community composition in these forest patches. Twenty six forest patches across the Eastern Cape were sampled. In each forest 400m2 circular plots were constructed. The diameter at breast height and stem counts for the tree species was taken and the % cover of the herbaceous species was recorded. General collections were also made to supplement the plot data in order to obtain a comprehensive flora for each forest patch. All sampling was done during the summer season of 2013 and 2014. Using plot data, Hierarchal Cluster Analysis and Multidimensional Scaling Analysis were done to compare similarities between patches. Plots from the same forest patch clustered which indicated that the species composition in each forest patch was unique. However, this pattern went down when only tree species were considered. Plant diversity also varied between patches; with those located in the east being generally more diverse than those in the west are. Clustering patterns in fragmented communities and differences in species diversity indicate evidence of species “nestedness”. Analysis of nestedness indicated that these forest patches were significantly nested. To identify which environmental variables might be correlated with both species diversity and nestedness, twelve environmental variables was selected for analysis using Canonical Correspondence Analysis and Principal Component Analysis. Results show that Mean Annual Precipitation, Mean Annual Potential Evapotranspiration, and percentage of Organic Matter of the soil were most strongly correlated with the patterns of diversity observed in these forest patches. Regression analysis indicated that Mean Annual Precipitation accounted for most of the variation in species diversity, especially for the herbaceous species. The herbaceous species thus show a greater sensitivity to “climate filtering” as a consequence of rainfall gradients. With the implementation of suitable monitoring programs, changes in abundance or even local extinction of these species can act as an early warning indicator of the possible long-term effects of climate change on forest communities.
- Full Text:
- Authors: Matiwane, Aviwe
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3224 , vital:20393
- Description: In the Eastern Cape, a moisture gradient (from west to east) exists along the Escarpment where patches of Southern Mistbelt Forests (SMF) occur. There is a notable profusion of plants in these forests, but the factors that drive plant species composition and abundance in these patches is poorly understood and such knowledge is critical if we are to address or mitigate the problems imposed by global change. Many of our ideas on plant community assembly are based on the premise that species differ in their environmental requirements for successful regeneration, especially when young. The aims of this study were to document the floristic diversity of poorly known patches of Southern Mistbelt Forests in the Eastern Cape and identify the environmental factors that influence plant community composition in these forest patches. Twenty six forest patches across the Eastern Cape were sampled. In each forest 400m2 circular plots were constructed. The diameter at breast height and stem counts for the tree species was taken and the % cover of the herbaceous species was recorded. General collections were also made to supplement the plot data in order to obtain a comprehensive flora for each forest patch. All sampling was done during the summer season of 2013 and 2014. Using plot data, Hierarchal Cluster Analysis and Multidimensional Scaling Analysis were done to compare similarities between patches. Plots from the same forest patch clustered which indicated that the species composition in each forest patch was unique. However, this pattern went down when only tree species were considered. Plant diversity also varied between patches; with those located in the east being generally more diverse than those in the west are. Clustering patterns in fragmented communities and differences in species diversity indicate evidence of species “nestedness”. Analysis of nestedness indicated that these forest patches were significantly nested. To identify which environmental variables might be correlated with both species diversity and nestedness, twelve environmental variables was selected for analysis using Canonical Correspondence Analysis and Principal Component Analysis. Results show that Mean Annual Precipitation, Mean Annual Potential Evapotranspiration, and percentage of Organic Matter of the soil were most strongly correlated with the patterns of diversity observed in these forest patches. Regression analysis indicated that Mean Annual Precipitation accounted for most of the variation in species diversity, especially for the herbaceous species. The herbaceous species thus show a greater sensitivity to “climate filtering” as a consequence of rainfall gradients. With the implementation of suitable monitoring programs, changes in abundance or even local extinction of these species can act as an early warning indicator of the possible long-term effects of climate change on forest communities.
- Full Text:
The trophic and spatial ecology of juvenile porcupine rays Urogymnus asperrimus at the remote St. Joseph Atoll
- Authors: Elston, Chantel
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/965 , vital:20007
- Description: Little information exists for the widely occurring but rare porcupine ray Urogymnus asperrimus. This is a concern given that it is a vulnerable species and likely plays an important ecological role in tropical atoll ecosystems. The aims of this thesis were to investigate the trophic and spatial ecology of juvenile porcupine rays within the St. Joseph Atoll, which is hypothesized to be functioning as a nursery for this species. Specific objectives were to determine i) the dietary composition and resource selectivity displayed by juvenile porcupine rays, ii) residency to the atoll, space use, and seasonality in movements, and iii) whether environmental factors affect short-term movements. Gastric lavage was used to collect stomach contents from 55 juveniles and sediment samples were collected. Thirteen juveniles were implanted with acoustic transmitters and monitored for a year by an array of 88 acoustic receivers situated in and around the St. Joseph Atoll. Porcupine rays appeared to be generalist and opportunistic feeders, foraging predominantly on annelids with the highest environmental availability. Polychaetes of the family Capitellidae were the most important prey item (Index of Importance = 35%). Rays only fed on deep infaunal prey, likely because of their foraging behaviour, suggesting they may influence this community. There was a size-related shift in the crustacean families consumed. The tagged rays displayed high residency to the atoll (mean residency index of 64%) and restricted movements, with small core use and activity space areas (mean of 0.5km² and 3km² respectively) and the majority of detections were recorded within 1km of their tagging locations. The rays favoured the sand ats where 88% of detections occurred. Transient use of the lagoon and fringe reef peaked in the north-west monsoon season, indicating a seasonal usage of these habitats. The effects of temperature and water depth on movements were manifested as diel and tidal cyclical patterns in presence. Evidence illustrates that the St. Joseph Atoll constitutes an important nursery for this species, which has been declared a Marine Protected Area. A major determinant behind the dependence of this nursery habitat is related to predator avoidance. Thermoregulatory behaviours were identified, suggesting that this species is vulnerable to climate change.
- Full Text:
- Authors: Elston, Chantel
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/965 , vital:20007
- Description: Little information exists for the widely occurring but rare porcupine ray Urogymnus asperrimus. This is a concern given that it is a vulnerable species and likely plays an important ecological role in tropical atoll ecosystems. The aims of this thesis were to investigate the trophic and spatial ecology of juvenile porcupine rays within the St. Joseph Atoll, which is hypothesized to be functioning as a nursery for this species. Specific objectives were to determine i) the dietary composition and resource selectivity displayed by juvenile porcupine rays, ii) residency to the atoll, space use, and seasonality in movements, and iii) whether environmental factors affect short-term movements. Gastric lavage was used to collect stomach contents from 55 juveniles and sediment samples were collected. Thirteen juveniles were implanted with acoustic transmitters and monitored for a year by an array of 88 acoustic receivers situated in and around the St. Joseph Atoll. Porcupine rays appeared to be generalist and opportunistic feeders, foraging predominantly on annelids with the highest environmental availability. Polychaetes of the family Capitellidae were the most important prey item (Index of Importance = 35%). Rays only fed on deep infaunal prey, likely because of their foraging behaviour, suggesting they may influence this community. There was a size-related shift in the crustacean families consumed. The tagged rays displayed high residency to the atoll (mean residency index of 64%) and restricted movements, with small core use and activity space areas (mean of 0.5km² and 3km² respectively) and the majority of detections were recorded within 1km of their tagging locations. The rays favoured the sand ats where 88% of detections occurred. Transient use of the lagoon and fringe reef peaked in the north-west monsoon season, indicating a seasonal usage of these habitats. The effects of temperature and water depth on movements were manifested as diel and tidal cyclical patterns in presence. Evidence illustrates that the St. Joseph Atoll constitutes an important nursery for this species, which has been declared a Marine Protected Area. A major determinant behind the dependence of this nursery habitat is related to predator avoidance. Thermoregulatory behaviours were identified, suggesting that this species is vulnerable to climate change.
- Full Text:
The use of treated brewery effluent as a water and nutrient source in crop irrigation
- Authors: Taylor, Richard Peter
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5390 , http://hdl.handle.net/10962/d1021265
- Description: Brewery effluent (BE) needs to be treated before it can be released into the environment, reused or used in down-stream activities. Current technologies used to address this concern at the experimental wastewater treatment plant at Ibahyi Brewery (SAB Ltd) include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW). The aim of this work was to determine if BE treated in these systems might be suitable for crop irrigation. A test crop, cabbage (Brassica oleracea cv. Star 3301), grew best on post-AD and post-PFP BE compared to those irrigated with post-HRAP or post-CW effluent. However, the yield was 13% lower than cabbage plants irrigated with a commercial nutrient solution and fresh water. The relatively high conductivity (3019.05 ± 48.72 μs/cm2) of BE may be the main factor reducing the cabbage yields. Post-HRAP and post-CW BE were the least suitable for irrigated crop production due to the higher conductivity and lower nutrient content of these treated effluents. After three months, soils irrigated with post-AD and post-PFP BE had a significantly higher sodium content and sodium adsorption ratio (3919 ± 94.77 mg/kg & 8.18 ± 0.17) than soil irrigated with a commercial nutrient solution (920.58 ± 27.46 mg/kg & 2.20 ± 0.05; p<0.05). However, this was not accompanied by a deterioration in the soil’s hydro-physical properties, nor a change in the metabolic community structure of the soil (p>0.05). After prolonged irrigation with treated BE, sodium is likely to build up in the soil and this can be expected to be accompanied by a deterioration in the soil physical structure. However, crops species such as millet (Echinochloa esculenta), lucerne (Medicago sativa) and saltbush (Atriplex nummularia) reduced the build-up of sodium in the soil. The results suggest that sodium was mainly removed from the soil through plant-assisted leaching. Of the crops grown, lucerne showed the most promise because it improved the soil physical properties, is able to grow well in alkaline environments, is a popular fodder crop and can be harvested multiple times from a single stand. Brewery effluent is more suitable for soil production systems than hydroponic production systems because the soil was able to act as a buffer against the high pH of post-AD BE, whereas in a hydroponics systems the high pH reduced the availability of key minerals to plants. In conclusion brewery effluent contains sufficient plants nutrients to support the growth of cabbages, saltbush, lucerne and millet. However the sodium content of BE is a concern as it accumulates in the soil, and in the long-term it may lead to soil degradation. It is suggested that the brewery change the pH neutralising treatment of BE from sodium hydroxide to potassium hydroxide, or dolomitic lime (calcium and magnesium carbonate) because this would reduce the introduction of sodium into the system, and would increase the suitability of BE for crop production, given potassium and calcium are plant nutrients. The benefits of developing this nutrient and water resource could contribute to cost-reductions at the brewery, more efficient water, nutrient and energy management, create job opportunities with the potential of improving food security in the local community.
- Full Text:
- Authors: Taylor, Richard Peter
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5390 , http://hdl.handle.net/10962/d1021265
- Description: Brewery effluent (BE) needs to be treated before it can be released into the environment, reused or used in down-stream activities. Current technologies used to address this concern at the experimental wastewater treatment plant at Ibahyi Brewery (SAB Ltd) include anaerobic digestion (AD), primary facultative ponds (PFP), high rate algal ponds (HRAP) and constructed wetlands (CW). The aim of this work was to determine if BE treated in these systems might be suitable for crop irrigation. A test crop, cabbage (Brassica oleracea cv. Star 3301), grew best on post-AD and post-PFP BE compared to those irrigated with post-HRAP or post-CW effluent. However, the yield was 13% lower than cabbage plants irrigated with a commercial nutrient solution and fresh water. The relatively high conductivity (3019.05 ± 48.72 μs/cm2) of BE may be the main factor reducing the cabbage yields. Post-HRAP and post-CW BE were the least suitable for irrigated crop production due to the higher conductivity and lower nutrient content of these treated effluents. After three months, soils irrigated with post-AD and post-PFP BE had a significantly higher sodium content and sodium adsorption ratio (3919 ± 94.77 mg/kg & 8.18 ± 0.17) than soil irrigated with a commercial nutrient solution (920.58 ± 27.46 mg/kg & 2.20 ± 0.05; p<0.05). However, this was not accompanied by a deterioration in the soil’s hydro-physical properties, nor a change in the metabolic community structure of the soil (p>0.05). After prolonged irrigation with treated BE, sodium is likely to build up in the soil and this can be expected to be accompanied by a deterioration in the soil physical structure. However, crops species such as millet (Echinochloa esculenta), lucerne (Medicago sativa) and saltbush (Atriplex nummularia) reduced the build-up of sodium in the soil. The results suggest that sodium was mainly removed from the soil through plant-assisted leaching. Of the crops grown, lucerne showed the most promise because it improved the soil physical properties, is able to grow well in alkaline environments, is a popular fodder crop and can be harvested multiple times from a single stand. Brewery effluent is more suitable for soil production systems than hydroponic production systems because the soil was able to act as a buffer against the high pH of post-AD BE, whereas in a hydroponics systems the high pH reduced the availability of key minerals to plants. In conclusion brewery effluent contains sufficient plants nutrients to support the growth of cabbages, saltbush, lucerne and millet. However the sodium content of BE is a concern as it accumulates in the soil, and in the long-term it may lead to soil degradation. It is suggested that the brewery change the pH neutralising treatment of BE from sodium hydroxide to potassium hydroxide, or dolomitic lime (calcium and magnesium carbonate) because this would reduce the introduction of sodium into the system, and would increase the suitability of BE for crop production, given potassium and calcium are plant nutrients. The benefits of developing this nutrient and water resource could contribute to cost-reductions at the brewery, more efficient water, nutrient and energy management, create job opportunities with the potential of improving food security in the local community.
- Full Text:
Thermoluminescence of annealed synthetic quartz
- Atang, Elizabeth Fende Midiki
- Authors: Atang, Elizabeth Fende Midiki
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/420 , vital:19957
- Description: The kinetic and dosimetric features of the main thermoluminescent peak of synthetic quartz have been investigated in quartz ordinarily annealed at 500_C as well as quartz annealed at 500_C for 10 minutes. The main peak is found at 78 _C for the samples annealed at 500_C for 10 minutes irradiated to 10 Gy and heated at 1.0 _C/s. For the samples ordinarily annealed at 500_C the main peak is found at 106 _C after the sample has been irradiated to 30 Gy and heated at 5.0 _C/s. In these samples, the intensity of the main peak is enhanced with repetitive measurement whereas its maximum temperature is unaffected. The peak position of the main peak in the sample is independent of the irradiation dose and this, together with its fading characteristics, are consistent with first-order kinetics. For doses between 5 and 25 Gy, the dose response of the main peak of the annealed sample is superlinear. The half-life of the main TL peak of the annealed sample is about 1 h. The activation energy E of the main peak is around 0.90 eV. For a heating rate of 0.4 _C/s, its order of kinetics b derived from the whole curve method of analysis is 1.0. Following irradiation, preheating and illumination with 470 nm blue light, the main peak in the annealed sample is regenerated during heating. The resulting phototransferred peak occurs at the same temperature as the original peak and has similar kinetic and dosimetric features, with a half-life of about 1 h. For a preheat temperature of 200 _C, the intensity of the phototransferred peak in the sample increases with illumination time up to a maximum and decreases thereafter. At longer illumination times, no further decrease in the intensity of the phototransferred peak is observed. The traps associated with the 325 _C peak are the main source of the electrons responsible for the regenerated peak.
- Full Text:
- Authors: Atang, Elizabeth Fende Midiki
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/420 , vital:19957
- Description: The kinetic and dosimetric features of the main thermoluminescent peak of synthetic quartz have been investigated in quartz ordinarily annealed at 500_C as well as quartz annealed at 500_C for 10 minutes. The main peak is found at 78 _C for the samples annealed at 500_C for 10 minutes irradiated to 10 Gy and heated at 1.0 _C/s. For the samples ordinarily annealed at 500_C the main peak is found at 106 _C after the sample has been irradiated to 30 Gy and heated at 5.0 _C/s. In these samples, the intensity of the main peak is enhanced with repetitive measurement whereas its maximum temperature is unaffected. The peak position of the main peak in the sample is independent of the irradiation dose and this, together with its fading characteristics, are consistent with first-order kinetics. For doses between 5 and 25 Gy, the dose response of the main peak of the annealed sample is superlinear. The half-life of the main TL peak of the annealed sample is about 1 h. The activation energy E of the main peak is around 0.90 eV. For a heating rate of 0.4 _C/s, its order of kinetics b derived from the whole curve method of analysis is 1.0. Following irradiation, preheating and illumination with 470 nm blue light, the main peak in the annealed sample is regenerated during heating. The resulting phototransferred peak occurs at the same temperature as the original peak and has similar kinetic and dosimetric features, with a half-life of about 1 h. For a preheat temperature of 200 _C, the intensity of the phototransferred peak in the sample increases with illumination time up to a maximum and decreases thereafter. At longer illumination times, no further decrease in the intensity of the phototransferred peak is observed. The traps associated with the 325 _C peak are the main source of the electrons responsible for the regenerated peak.
- Full Text:
Toward an automated botnet analysis framework: a darkcomet case-study
- Authors: du Bruyn, Jeremy Cecil
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2937 , vital:20344
- Full Text:
- Authors: du Bruyn, Jeremy Cecil
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/2937 , vital:20344
- Full Text:
Towards an alternative spatial-based management approach for estuarine fisheries in South Africa, with a case study from the Sundays Estuary
- Authors: Kramer, Rachel
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1007 , vital:20012
- Description: Estuaries are productive habitats and biologically important ecosystems which serve as juvenile nursery areas and feeding grounds for adults from a host of fish species. They are, however, threatened habitats, increasingly exposed to human disturbance and exploitation. The stocks of several South African estuary-dependent linefish species are now considered as either overexploited or collapsed. It is clear that their dependence on estuaries would warrant the inclusion of these ecosystems into marine reserve planning exercises. Since traditional management strategies (e.g. bag and size limit restrictions) have proven ineffective for estuarine fisheries, there is a need for alternative management measures, such as spatial and temporal restrictions, to ensure increased survival of juveniles and recovery of adult breeding populations. This thesis explored the potential for an ecosystem-based approach through the application of a rapid sustainability assessment technique, and a spatial-based management approach for an important fishery species, using conservation planning software. The Sundays Estuary, Eastern Cape, South Africa falls within the footprint of the Addo Elephant National Park, with a proposed expansion to include a marine protected area (MPA). However the estuaries resources were not considered during the planning of the proposed MPA. This study conducted an indicator-based sustainability assessment based on the principles of sustainable development. The results showed that present levels of exploitation, due to non-compliance and a lack of law enforcement are unsustainable. The sustainability of the Sundays Estuary had a low overall sustainability score of only 23.8%. With limited enforcement of estuarine fisheries regulations in South Africa, alternative management measures such as spatial regulations may provide a viable option forward. The sustainability of fishery resources depends on the comprehensive understanding of the fishery resource. Acoustic telemetry is a technique that has been widely adopted to infer habitat and area use patterns of fish species. The second component of this study made use of high resolution telemetry data collected on juvenile dusky kob Argyrosomus japonicus movements within the Sundays Estuary to conduct a scenario-based approach using Marxan conservation planning software. The best solution given by Marxan, in the form of a protected area for the conservation of juvenile A. japonicus in the Sundays Estuary was identified in the middle (starting 7km from the mouth) to the upper reaches (approximately 16km from the mouth) of the estuary, ultimately providing protection to tagged individuals for 61% of their time in the estuary. Although Marxan presented a best solution, the Sundays Estuary’s small size and shape, and minimal features used, was too simplistic to be included into a Marxan analysis. However, new methods and tools to analyse and plan spatial-based management options at this scale are currently being developed. Using the Sundays Estuary as a case study, a decision tree was then developed as a protocol to assist management address the challenges of effective estuarine management depending on the unique biological and socio-economic characteristics of individual estuaries in South Africa.
- Full Text:
- Authors: Kramer, Rachel
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1007 , vital:20012
- Description: Estuaries are productive habitats and biologically important ecosystems which serve as juvenile nursery areas and feeding grounds for adults from a host of fish species. They are, however, threatened habitats, increasingly exposed to human disturbance and exploitation. The stocks of several South African estuary-dependent linefish species are now considered as either overexploited or collapsed. It is clear that their dependence on estuaries would warrant the inclusion of these ecosystems into marine reserve planning exercises. Since traditional management strategies (e.g. bag and size limit restrictions) have proven ineffective for estuarine fisheries, there is a need for alternative management measures, such as spatial and temporal restrictions, to ensure increased survival of juveniles and recovery of adult breeding populations. This thesis explored the potential for an ecosystem-based approach through the application of a rapid sustainability assessment technique, and a spatial-based management approach for an important fishery species, using conservation planning software. The Sundays Estuary, Eastern Cape, South Africa falls within the footprint of the Addo Elephant National Park, with a proposed expansion to include a marine protected area (MPA). However the estuaries resources were not considered during the planning of the proposed MPA. This study conducted an indicator-based sustainability assessment based on the principles of sustainable development. The results showed that present levels of exploitation, due to non-compliance and a lack of law enforcement are unsustainable. The sustainability of the Sundays Estuary had a low overall sustainability score of only 23.8%. With limited enforcement of estuarine fisheries regulations in South Africa, alternative management measures such as spatial regulations may provide a viable option forward. The sustainability of fishery resources depends on the comprehensive understanding of the fishery resource. Acoustic telemetry is a technique that has been widely adopted to infer habitat and area use patterns of fish species. The second component of this study made use of high resolution telemetry data collected on juvenile dusky kob Argyrosomus japonicus movements within the Sundays Estuary to conduct a scenario-based approach using Marxan conservation planning software. The best solution given by Marxan, in the form of a protected area for the conservation of juvenile A. japonicus in the Sundays Estuary was identified in the middle (starting 7km from the mouth) to the upper reaches (approximately 16km from the mouth) of the estuary, ultimately providing protection to tagged individuals for 61% of their time in the estuary. Although Marxan presented a best solution, the Sundays Estuary’s small size and shape, and minimal features used, was too simplistic to be included into a Marxan analysis. However, new methods and tools to analyse and plan spatial-based management options at this scale are currently being developed. Using the Sundays Estuary as a case study, a decision tree was then developed as a protocol to assist management address the challenges of effective estuarine management depending on the unique biological and socio-economic characteristics of individual estuaries in South Africa.
- Full Text:
Towards determining the dietary lysine requirement in the South African abalone, Haliotis midae
- Authors: Lloyd, Kyle Everett
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1024 , vital:20014
- Description: Animals generally do not have a requirement for protein, but instead have a requirement for specific essential amino acids (EAAs) and non-essential amino acids (NEAAs). The NEAAs are those that can be synthesised by the animal, however, EAAs cannot be synthesised and must therefore be supplied as part of the diet. When these amino acids (AAs) are supplied in the correct ratios and with the correct level of digestible energy, nutritionists can maximise somatic growth from proteins. This has resulted in increased research into the use of crystalline AAs as a tool in feed formulation research in order to quantify the AA requirements in aquaculture species, and allow for alternative protein sources (other than fishmeal) to be utilised. In common with other water soluble nutrients, leaching of crystalline AAs from diets prior to ingestion is of concern in an aquatic environment. Microencapsulation techniques have been successfully employed to restrict micronutrient leaching, and improve ingestion rates. In this research, LysiPEARL™ (Kemin®) was used as a means to determine the lysine requirement in Haliotis. midae. This encapsulated lysine product is used in the dairy cattle industry as an effective source of rumen bypass for intestinal release of lysine. It has previously been proposed that crystalline AAs are not suitable for AA studies in H. midae due to the slow feeding rates of the species as well as the solubility of these AAs. However, 90.00 % of supplemented lysine was maintained in this study after a six hour period of leaching, showing that if effective microencapsulation techniques are used, it is possible to use crystalline amino acids to supplement protein bound lysine in abalone feeds. Six isoenergetic (15.90 MJ/kg), isolipidic (6.00 %) and isonitrogenous (29.00 %) diets enriched with 5.52, 6.40, 7.28, 8.14, 9.00 and 9.86 % lysine (as a % of protein) were fed to triplicate groups of 20 H. midae (20.41 ± 1.95 mm SL 1.51 ± 0.44 g w.wt) for 90 days. Wet weight and shell length measurements were taken every 30 days and specific growth rate (SGR) (% body weight.day-1), feed conversion ratio (FCR), protein efficiency ratio (PER), feed consumption (% body weight.day-1) and condition factor were calculated for each dietary treatment. Linear regression showed that FCR increased as dietary lysine increased (Regression analysis, p=0.031), and that PER reduced as dietary lysine increased (Regression analysis, p=0.026). Feed consumption also increased as dietary lysine increased (Regression analysis, p<0.001). The inclusion of lysine at 7.28 % of the total protein in the diet resulted in significantly superior SGR (0.57±0.01 % body weight.day-1) to that of 5.52 % (0.42±0.05 % body weight.day-1), FCR (1.51±0.05) to that of 8.14 % (1.99±0.21) and PER (2.45±0.07) to that of 8.14 % (1.99±0.18; ANOVA, p<0.05). There was a significant difference found in feed consumption (% body wt.d-1), with consumption increasing significantly between the first three dietary treatments and the last three dietary treatments (ANOVA, p<0.001). There was no significant improvement in SGR when dietary lysine increased above 7.28 % of the dietary protein in the diet, indicating that dietary lysine requirement was being met at 7.28 %, after which excess lysine promoted no growth response. The diet producing the best SGR, PER and FCR in this study was diet 3 which had a measured lysine content of 6.90 %. The results of the present study suggest that the lysine requirement in H. midae is in the range of 6.00 - 7.00 % of dietary protein. From these data amino acid ratios were used to estimate optimum inclusion levels of other essential amino acids. However, lysine availability in LysiPEARL™ may have resulted in over estimations due to the lipid encapsulation technique used, and haliotids limited ability to efficiently digest lipids. For this reason EAA requirements were suggested based on three different hypothetical scenarios of lysine availability from LysiPEARL™.
- Full Text:
- Authors: Lloyd, Kyle Everett
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1024 , vital:20014
- Description: Animals generally do not have a requirement for protein, but instead have a requirement for specific essential amino acids (EAAs) and non-essential amino acids (NEAAs). The NEAAs are those that can be synthesised by the animal, however, EAAs cannot be synthesised and must therefore be supplied as part of the diet. When these amino acids (AAs) are supplied in the correct ratios and with the correct level of digestible energy, nutritionists can maximise somatic growth from proteins. This has resulted in increased research into the use of crystalline AAs as a tool in feed formulation research in order to quantify the AA requirements in aquaculture species, and allow for alternative protein sources (other than fishmeal) to be utilised. In common with other water soluble nutrients, leaching of crystalline AAs from diets prior to ingestion is of concern in an aquatic environment. Microencapsulation techniques have been successfully employed to restrict micronutrient leaching, and improve ingestion rates. In this research, LysiPEARL™ (Kemin®) was used as a means to determine the lysine requirement in Haliotis. midae. This encapsulated lysine product is used in the dairy cattle industry as an effective source of rumen bypass for intestinal release of lysine. It has previously been proposed that crystalline AAs are not suitable for AA studies in H. midae due to the slow feeding rates of the species as well as the solubility of these AAs. However, 90.00 % of supplemented lysine was maintained in this study after a six hour period of leaching, showing that if effective microencapsulation techniques are used, it is possible to use crystalline amino acids to supplement protein bound lysine in abalone feeds. Six isoenergetic (15.90 MJ/kg), isolipidic (6.00 %) and isonitrogenous (29.00 %) diets enriched with 5.52, 6.40, 7.28, 8.14, 9.00 and 9.86 % lysine (as a % of protein) were fed to triplicate groups of 20 H. midae (20.41 ± 1.95 mm SL 1.51 ± 0.44 g w.wt) for 90 days. Wet weight and shell length measurements were taken every 30 days and specific growth rate (SGR) (% body weight.day-1), feed conversion ratio (FCR), protein efficiency ratio (PER), feed consumption (% body weight.day-1) and condition factor were calculated for each dietary treatment. Linear regression showed that FCR increased as dietary lysine increased (Regression analysis, p=0.031), and that PER reduced as dietary lysine increased (Regression analysis, p=0.026). Feed consumption also increased as dietary lysine increased (Regression analysis, p<0.001). The inclusion of lysine at 7.28 % of the total protein in the diet resulted in significantly superior SGR (0.57±0.01 % body weight.day-1) to that of 5.52 % (0.42±0.05 % body weight.day-1), FCR (1.51±0.05) to that of 8.14 % (1.99±0.21) and PER (2.45±0.07) to that of 8.14 % (1.99±0.18; ANOVA, p<0.05). There was a significant difference found in feed consumption (% body wt.d-1), with consumption increasing significantly between the first three dietary treatments and the last three dietary treatments (ANOVA, p<0.001). There was no significant improvement in SGR when dietary lysine increased above 7.28 % of the dietary protein in the diet, indicating that dietary lysine requirement was being met at 7.28 %, after which excess lysine promoted no growth response. The diet producing the best SGR, PER and FCR in this study was diet 3 which had a measured lysine content of 6.90 %. The results of the present study suggest that the lysine requirement in H. midae is in the range of 6.00 - 7.00 % of dietary protein. From these data amino acid ratios were used to estimate optimum inclusion levels of other essential amino acids. However, lysine availability in LysiPEARL™ may have resulted in over estimations due to the lipid encapsulation technique used, and haliotids limited ability to efficiently digest lipids. For this reason EAA requirements were suggested based on three different hypothetical scenarios of lysine availability from LysiPEARL™.
- Full Text:
Using bioinformatics tools to screen for trypanosomal cathepsin B cysteine protease inhibitors from the SANCDB as a novel therapeutic modality against Human African Trypanosomiasis (HAT)
- Authors: Mokhawa, Gaone
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3304 , vital:20470
- Description: Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a fatal chronic disease that is caused by flagellated protozoans, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. HAT is spread by a bite from an infected tsetse fly of the Glosina genus. Up to 60 million people in 36 countries in sub-Saharan Africa are at a risk of infection from HAT with up to 30 000 deaths reported every year. Current chemotherapy for HAT is insufficient since the available drugs exhibit unacceptable side effects (toxicity) and parasite resistance. Novel treatments and approaches for development of specific and more potent drugs for HAT are therefore required. One approach is to target vital proteins that are essential to the life cycle of the parasite. The main interest of this study is to explore Trypanosoma brucei cathepsin B-like protease (TbCatB) structural and functional properties with the primary goal of discovering non peptide small molecule inhibitors of TbCatB using bioinformatics approaches. TbCatB is a papain family C1 cysteine protease which belongs to clan CA group and it has emerged as a potential HAT drug target. Papain family cysteine proteases of Clan CA group of Trypanosoma brucei (rhodesain and TbCatB) have demonstrated potential as chemotherapeutic targets using synthetic protease inhibitors like Z-Phe-Ala-CHN2 to kill the parasite in vitro and in vivo. TbCatB has been identified as the essential cysteine protease of T. brucei since mRNA silencing of TbCatB killed the parasite and resulted in a cure in mice infected with T. brucei while mRNA silencing of rhodesain only extended mice life. TbCatB is therefore a promising drug target against HAT and the discovery and development of compounds that can selectively inhibit TbCatB without posing any danger to the human host represent a great therapeutic solution for treatment of HAT. To understand protein-inhibitor interactions, useful information can be obtained from high resolution protease-inhibitor crystal structure complexes. This study aims to use bioinformatics approaches to carry out comparative sequence, structural and functional analysis of TbCatB protease and its homologs from T. congolense, T, cruzi, T. vivax and H. sapien as well as to identify non-peptide small molecule inhibitors of TbCatB cysteine proteases from natural compounds of South African origin. Sequences of TbCatB (PDB ID: 3HHI) homologs were retrieved by a BLAST search. Human cathepsin B (PDB ID: 3CBJ) was selected from a list of templates for homology modelling found by HHpred. MODELLER version 9.10 program was used to generate a hundred models for T. congolense, T, cruzi and T. vivax cathepsin B like proteases using 3HHI and 3CBJ as templates. The best models were chosen based on their low DOPE Z scores before validation using MetaMQAPII, ANOLEA, PROCHECK and QMEAN6. The DOPE Z scores and the RMSD (RMS) values of the calculated models indicate that the models are of acceptable energy (stability) and fold (conformation). Results from the different MQAPs indicate the models are of acceptable quality and they can be used for docking studies. High throughput screening of SANCDB using AutoDock Vina revealed nine compounds, SANC00 478, 479, 480, 481, 482, 488, 489, 490 and 491, having a strong affinity for Trypanosoma spp. cathepsin B proteases than HsCatB. SANC00488 has the strongest binding to Trypanosoma spp. cathepsin B proteases and the weakest binding to HsCatB protease. Molecular dynamics (MD) simulations show that the complexes between SANC00488 and TbCatB, TcCatB, TcrCatB and TvCatB are stable and do not come apart during simulation. The complex between this compound and HsCatB however is unstable and comes apart during simulation. Residues that are important for the stability of SANC00488-TbCatB complex are Gly328 of the S2 subsite, Phe208, and Ala256. In conclusion SANC00488 is a good candidate for development of a drug against HAT.
- Full Text:
- Authors: Mokhawa, Gaone
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3304 , vital:20470
- Description: Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a fatal chronic disease that is caused by flagellated protozoans, Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense. HAT is spread by a bite from an infected tsetse fly of the Glosina genus. Up to 60 million people in 36 countries in sub-Saharan Africa are at a risk of infection from HAT with up to 30 000 deaths reported every year. Current chemotherapy for HAT is insufficient since the available drugs exhibit unacceptable side effects (toxicity) and parasite resistance. Novel treatments and approaches for development of specific and more potent drugs for HAT are therefore required. One approach is to target vital proteins that are essential to the life cycle of the parasite. The main interest of this study is to explore Trypanosoma brucei cathepsin B-like protease (TbCatB) structural and functional properties with the primary goal of discovering non peptide small molecule inhibitors of TbCatB using bioinformatics approaches. TbCatB is a papain family C1 cysteine protease which belongs to clan CA group and it has emerged as a potential HAT drug target. Papain family cysteine proteases of Clan CA group of Trypanosoma brucei (rhodesain and TbCatB) have demonstrated potential as chemotherapeutic targets using synthetic protease inhibitors like Z-Phe-Ala-CHN2 to kill the parasite in vitro and in vivo. TbCatB has been identified as the essential cysteine protease of T. brucei since mRNA silencing of TbCatB killed the parasite and resulted in a cure in mice infected with T. brucei while mRNA silencing of rhodesain only extended mice life. TbCatB is therefore a promising drug target against HAT and the discovery and development of compounds that can selectively inhibit TbCatB without posing any danger to the human host represent a great therapeutic solution for treatment of HAT. To understand protein-inhibitor interactions, useful information can be obtained from high resolution protease-inhibitor crystal structure complexes. This study aims to use bioinformatics approaches to carry out comparative sequence, structural and functional analysis of TbCatB protease and its homologs from T. congolense, T, cruzi, T. vivax and H. sapien as well as to identify non-peptide small molecule inhibitors of TbCatB cysteine proteases from natural compounds of South African origin. Sequences of TbCatB (PDB ID: 3HHI) homologs were retrieved by a BLAST search. Human cathepsin B (PDB ID: 3CBJ) was selected from a list of templates for homology modelling found by HHpred. MODELLER version 9.10 program was used to generate a hundred models for T. congolense, T, cruzi and T. vivax cathepsin B like proteases using 3HHI and 3CBJ as templates. The best models were chosen based on their low DOPE Z scores before validation using MetaMQAPII, ANOLEA, PROCHECK and QMEAN6. The DOPE Z scores and the RMSD (RMS) values of the calculated models indicate that the models are of acceptable energy (stability) and fold (conformation). Results from the different MQAPs indicate the models are of acceptable quality and they can be used for docking studies. High throughput screening of SANCDB using AutoDock Vina revealed nine compounds, SANC00 478, 479, 480, 481, 482, 488, 489, 490 and 491, having a strong affinity for Trypanosoma spp. cathepsin B proteases than HsCatB. SANC00488 has the strongest binding to Trypanosoma spp. cathepsin B proteases and the weakest binding to HsCatB protease. Molecular dynamics (MD) simulations show that the complexes between SANC00488 and TbCatB, TcCatB, TcrCatB and TvCatB are stable and do not come apart during simulation. The complex between this compound and HsCatB however is unstable and comes apart during simulation. Residues that are important for the stability of SANC00488-TbCatB complex are Gly328 of the S2 subsite, Phe208, and Ala256. In conclusion SANC00488 is a good candidate for development of a drug against HAT.
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A comparison of open source and proprietary digital forensic software
- Authors: Sonnekus, Michael Hendrik
- Date: 2015
- Subjects: Computer crimes , Computer crimes -- Investigation , Electronic evidence , Open source software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4717 , http://hdl.handle.net/10962/d1017939
- Description: Scrutiny of the capabilities and accuracy of computer forensic tools is increasing as the number of incidents relying on digital evidence and the weight of that evidence increase. This thesis describes the capabilities of the leading proprietary and open source digital forensic tools. The capabilities of the tools were tested separately on digital media that had been formatted using Windows and Linux. Experiments were carried out with the intention of establishing whether the capabilities of open source computer forensics are similar to those of proprietary computer forensic tools, and whether these tools could complement one another. The tools were tested with regards to their capabilities to make and analyse digital forensic images in a forensically sound manner. The tests were carried out on each media type after deleting data from the media, and then repeated after formatting the media. The results of the experiments performed demonstrate that both proprietary and open source computer forensic tools have superior capabilities in different scenarios, and that the toolsets can be used to validate and complement one another. The implication of these findings is that investigators have an affordable means of validating their findings and are able to more effectively investigate digital media.
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- Authors: Sonnekus, Michael Hendrik
- Date: 2015
- Subjects: Computer crimes , Computer crimes -- Investigation , Electronic evidence , Open source software
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4717 , http://hdl.handle.net/10962/d1017939
- Description: Scrutiny of the capabilities and accuracy of computer forensic tools is increasing as the number of incidents relying on digital evidence and the weight of that evidence increase. This thesis describes the capabilities of the leading proprietary and open source digital forensic tools. The capabilities of the tools were tested separately on digital media that had been formatted using Windows and Linux. Experiments were carried out with the intention of establishing whether the capabilities of open source computer forensics are similar to those of proprietary computer forensic tools, and whether these tools could complement one another. The tools were tested with regards to their capabilities to make and analyse digital forensic images in a forensically sound manner. The tests were carried out on each media type after deleting data from the media, and then repeated after formatting the media. The results of the experiments performed demonstrate that both proprietary and open source computer forensic tools have superior capabilities in different scenarios, and that the toolsets can be used to validate and complement one another. The implication of these findings is that investigators have an affordable means of validating their findings and are able to more effectively investigate digital media.
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A flight of fancy in the Chorister Robin-Chat (Cossypha dichroa) : an isotopic standpoint
- Wolmarans, Milena Helena Louise
- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
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- Authors: Wolmarans, Milena Helena Louise
- Date: 2015
- Subjects: Muscicapidae -- South Africa , Muscicapidae -- Food , Muscicapidae -- Habitat , Muscicapidae -- Habitat -- Conservation , Forest birds -- South Africa , Isotopes , Stable isotope tracers
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5920 , http://hdl.handle.net/10962/d1017207
- Description: Forested areas have been cited for their highly diverse floral and faunal assemblages, which are currently under threat from anthropogenic activities that restrict their range and deplete the resources produced within these naturally fragmented patches. Historically, up to 67 percent of avifaunal species associated with well-treed areas have undergone localised extinctions, consequentially affecting biodiversity as a measure of species richness and ecosystem functionality. To date, more than 900 of the bird species affiliated with forests are under threat and despite the theory surrounding functional redundancy, the mass extinction that is currently underway poses considerable limitations on the ecological integrity of these biomes. In South Africa, indigenous forest (one of the rarest biomes), occurs predominantly in small isolated patches along the eastern escarpment. With mountainous terrain emphasised as ‘prominent hotspots of extinction’, the limited dispersal and habitat sensitivity of montane forest fauna renders these species more prone to localised extinctions. BirdLife International, the IUCN and SABAP2 all indicate reductions in the range and abundance of the Chorister Robin-Chat (Cossypha dichroa) - an endemic forest specialist that is reported to move seasonally between high-altitude forest patches where they breed in summer, and lowland coastal forests where they overwinter. Beyond diet, body morphology and vocalisations, much of the information available on the altitudinal movements of C. dichroa is based on secondary sources and the assumptions therein. This study aimed to investigate the potential utilisation of δ13C and δ15N stable isotopes in determining the dietary niche width and altitudinal movements of C. dichroa. Feathers obtained in forested patches of the Limpopo, KwaZulu-Natal and Eastern Cape provinces exhibited a wide trophic niche width and generalised diet. Strong regional separation is apparent in the isotopic signatures suggesting little movement between provinces. A comparison of 13C-isotopes showed minimal variation that point to a uniformity in the carbon-base utilised by C. dichroa across their range. The 15N-signatures obtained in Limpopo, however, revealed a distinct trophic segregation between the northern-most Chorister populations and their southern counterparts. No altitudinal movements were detected in the isotopic signatures of recaptured Choristers, but more research is needed to investigate the long-term accuracy of these results and the breeding potential of resident Choristers in lowland coastal forests; especially when considering the reduced range and abundance reported for this endemic species.
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A Framework for using Open Source intelligence as a Digital Forensic Investigative tool
- Authors: Rule, Samantha Elizabeth
- Date: 2015
- Subjects: Open source intelligence , Criminal investigation , Electronic evidence
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4715 , http://hdl.handle.net/10962/d1017937
- Description: The proliferation of the Internet has amplified the use of social networking sites by creating a platform that encourages individuals to share information. As a result there is a wealth of information that is publically and easily accessible. This research explores whether open source intelligence (OSINT), which is freely available, could be used as a digital forensic investigative tool. A survey was created and sent to digital forensic investigators to establish whether they currently use OSINT when performing investigations. The survey results confirm that OSINT is being used by digital forensic investigators when performing investigations but there are currently no guidelines or frameworks available to support the use thereof. Additionally, the survey results showed a belief amongst those surveyed that evidence gleaned from OSINT sources is considered supplementary rather than evidentiary. The findings of this research led to the development of a framework that identifies and recommends key processes to follow when conducting OSINT investigations. The framework can assist digital forensic investigators to follow a structured and rigorous process, which may lead to the unanimous acceptance of information obtained via OSINT sources as evidentiary rather than supplementary in the near future.
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- Authors: Rule, Samantha Elizabeth
- Date: 2015
- Subjects: Open source intelligence , Criminal investigation , Electronic evidence
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4715 , http://hdl.handle.net/10962/d1017937
- Description: The proliferation of the Internet has amplified the use of social networking sites by creating a platform that encourages individuals to share information. As a result there is a wealth of information that is publically and easily accessible. This research explores whether open source intelligence (OSINT), which is freely available, could be used as a digital forensic investigative tool. A survey was created and sent to digital forensic investigators to establish whether they currently use OSINT when performing investigations. The survey results confirm that OSINT is being used by digital forensic investigators when performing investigations but there are currently no guidelines or frameworks available to support the use thereof. Additionally, the survey results showed a belief amongst those surveyed that evidence gleaned from OSINT sources is considered supplementary rather than evidentiary. The findings of this research led to the development of a framework that identifies and recommends key processes to follow when conducting OSINT investigations. The framework can assist digital forensic investigators to follow a structured and rigorous process, which may lead to the unanimous acceptance of information obtained via OSINT sources as evidentiary rather than supplementary in the near future.
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A geochemical and morphological investigation of placer gold grains from the southern Seward Peninsula, Alaska : implications for source and transport mechanisms
- Gauntlett, Ernest John Herbert
- Authors: Gauntlett, Ernest John Herbert
- Date: 2015
- Subjects: Placer deposits -- Alaska -- Seward Peninsula , Gold alloys , Gold mines and mining -- Alaska -- Seward Peninsula , Geochemical surveys -- Alaska -- Seward Peninsula , Trace elements -- Alaska -- Seward Peninsula , Drift -- Alaska -- Seward Peninsula , Gold -- Standards of fineness
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5085 , http://hdl.handle.net/10962/d1018202
- Description: [Partial abstract]: This study presents the first detailed geochemical and morphological characterisation of gold grains from the southern Seward Peninsula, Alaska, a region with significant historical and on-going placer gold mining. Quantitative Au, Ag, Hg, and Cu data are presented for gold grains from eleven sites. Additionally, quantitative Te, W, As, and Sb trace element data are presented for gold grains from ten of the eleven sites. Although it is acknowledged that quantitative trace element analysis of gold grains is a relatively new endeavour, the limited trace element data obtained in this study suggest that trace element analysis could be useful for characterising gold sources on the southern Seward Peninsula. Major and minor element geochemical profiling is sufficient at differentiating between sites from regional provenance systems but insufficient at differentiating between sites within a single system. Differentiating among sites within a single system will likely require microchemical analysis of mineral inclusions and analysis of trace element signatures.
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- Authors: Gauntlett, Ernest John Herbert
- Date: 2015
- Subjects: Placer deposits -- Alaska -- Seward Peninsula , Gold alloys , Gold mines and mining -- Alaska -- Seward Peninsula , Geochemical surveys -- Alaska -- Seward Peninsula , Trace elements -- Alaska -- Seward Peninsula , Drift -- Alaska -- Seward Peninsula , Gold -- Standards of fineness
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5085 , http://hdl.handle.net/10962/d1018202
- Description: [Partial abstract]: This study presents the first detailed geochemical and morphological characterisation of gold grains from the southern Seward Peninsula, Alaska, a region with significant historical and on-going placer gold mining. Quantitative Au, Ag, Hg, and Cu data are presented for gold grains from eleven sites. Additionally, quantitative Te, W, As, and Sb trace element data are presented for gold grains from ten of the eleven sites. Although it is acknowledged that quantitative trace element analysis of gold grains is a relatively new endeavour, the limited trace element data obtained in this study suggest that trace element analysis could be useful for characterising gold sources on the southern Seward Peninsula. Major and minor element geochemical profiling is sufficient at differentiating between sites from regional provenance systems but insufficient at differentiating between sites within a single system. Differentiating among sites within a single system will likely require microchemical analysis of mineral inclusions and analysis of trace element signatures.
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A light-emitting-diode pulsing system for measurement of time-resolved luminescence
- Authors: Uriri, Solomon Akpore
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20976 , http://hdl.handle.net/10962/5788
- Description: A new light-emitting-diode based pulsing system for measurement of time-resolved luminescence has been developed. The light-emitting-diodes are pulsed at various pulse-widths by a 555-timer operated as a monostable multivibrator. The light-emitting-diodes are arranged in a dural holder connected in parallel in sets of four, each containing four diodes in series. The output pulse from the 555-timer is fed into an 2N7000 MOSFET to produce a pulse-current of 500 mA to drive the set of 16 light-emitting-diodes. This size of current is sufficient to drive the diodes with each driven at a pulse-current of 90 mA with a possible maximum of 110 mA per diode. A multichannel scaler is used to trigger the pulsing system and to record data at selectable dwell times. The system is capable of generating pulse-widths in the range of microseconds upwards.
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- Authors: Uriri, Solomon Akpore
- Date: 2015
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:20976 , http://hdl.handle.net/10962/5788
- Description: A new light-emitting-diode based pulsing system for measurement of time-resolved luminescence has been developed. The light-emitting-diodes are pulsed at various pulse-widths by a 555-timer operated as a monostable multivibrator. The light-emitting-diodes are arranged in a dural holder connected in parallel in sets of four, each containing four diodes in series. The output pulse from the 555-timer is fed into an 2N7000 MOSFET to produce a pulse-current of 500 mA to drive the set of 16 light-emitting-diodes. This size of current is sufficient to drive the diodes with each driven at a pulse-current of 90 mA with a possible maximum of 110 mA per diode. A multichannel scaler is used to trigger the pulsing system and to record data at selectable dwell times. The system is capable of generating pulse-widths in the range of microseconds upwards.
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