Appropriate integration of workers with physical limitations into a manual workplace – development of an assessment tool
- Authors: Pearson, Jessie T
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/8209 , vital:21368
- Description: Background: People with physical limitations can contribute significantly to society and the economy, however, barriers to full and effective participation in the labour market often hinder decent employment. In light of this, placement decisions of impaired workers should be based on detailed information of the nature of the jobs available, as well as individual capabilities of the worker. An ergonomics approach to design attempts to achieve an appropriate balance between the capabilities of the worker and the requirements of the task and uses this balance to improve productivity and encourage physical and mental well-being, job satisfaction and safety. A specific analysis tool which can be applied to various workplaces and jobs, and provide information for decisions regarding placement of physically limited workers, will help to increase the percentage of correct placement in an appropriate workplace, resulting in optimum productivity and worker safety. Methods: An assessment tool which allows matching of job requirements and worker capabilities was developed based on a theoretical framework from Mattison and Goebel (2007), as well as principles defined by Almgren and Schaurig (2012) and Demura and Nakada (2010). The tool assesses range of motion, force and time components of the physical requirements of different tasks involved in the job, as well as movement capabilities and limitations of the worker. The tool was pilot tested in a case study with an above the knee amputee working at a research facility. Results: The tool successfully provided information regarding the matching of the work to the identified job. The output of the tool highlighted two tasks which would place the worker at risk due to physical requirements of the tasks being greater than movement capabilities of the worker. These tasks need to be further investigated to determine if accommodations can be made to assist the worker in safely performing the task, or if the job is not suitable for the worker. Conclusions: The tool developed was useful in providing information to inform appropriate placement of the physically limited worker. Further research needs to be done to validate and determine reliability of the tool.
- Full Text:
- Date Issued: 2017
- Authors: Pearson, Jessie T
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/8209 , vital:21368
- Description: Background: People with physical limitations can contribute significantly to society and the economy, however, barriers to full and effective participation in the labour market often hinder decent employment. In light of this, placement decisions of impaired workers should be based on detailed information of the nature of the jobs available, as well as individual capabilities of the worker. An ergonomics approach to design attempts to achieve an appropriate balance between the capabilities of the worker and the requirements of the task and uses this balance to improve productivity and encourage physical and mental well-being, job satisfaction and safety. A specific analysis tool which can be applied to various workplaces and jobs, and provide information for decisions regarding placement of physically limited workers, will help to increase the percentage of correct placement in an appropriate workplace, resulting in optimum productivity and worker safety. Methods: An assessment tool which allows matching of job requirements and worker capabilities was developed based on a theoretical framework from Mattison and Goebel (2007), as well as principles defined by Almgren and Schaurig (2012) and Demura and Nakada (2010). The tool assesses range of motion, force and time components of the physical requirements of different tasks involved in the job, as well as movement capabilities and limitations of the worker. The tool was pilot tested in a case study with an above the knee amputee working at a research facility. Results: The tool successfully provided information regarding the matching of the work to the identified job. The output of the tool highlighted two tasks which would place the worker at risk due to physical requirements of the tasks being greater than movement capabilities of the worker. These tasks need to be further investigated to determine if accommodations can be made to assist the worker in safely performing the task, or if the job is not suitable for the worker. Conclusions: The tool developed was useful in providing information to inform appropriate placement of the physically limited worker. Further research needs to be done to validate and determine reliability of the tool.
- Full Text:
- Date Issued: 2017
Investigation of the bioconversion of constituents of olive effluents for the production of valuable chemical compounds
- Authors: Notshe, Thandiwe Loretta
- Date: 2002
- Subjects: Phenols , Sewage -- Purification , Effluent quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4078 , http://hdl.handle.net/10962/d1007446 , Phenols , Sewage -- Purification , Effluent quality
- Description: Olive mill wastewater is produced in large quantities during the production of olive oil and olive production effluents are produced during the processing of olives. This project was planned to find a use for constituents found in olive production wastewater. The task was carried out by first characterizing the olive effluents, then screening microorganisms for growth in the effluents and reduction of the pollutant properties of the effluents. An investigation into the biotransformation of aromatic compounds present in the effluents into useful chemicals, was carried out. The olive production effluents were collected from different stages in the process for treating olive wastewater, viz, a fermentation tank (FB), the surface of a digester (LV) and an evaporation pond (SO). The three effluents were characterized by investigating their phenolic composition. Protocatechuic acid, vanillic acid, syringic acid, hydroxyphenyl acetic acid, coumaric acid and ferulic acid were identified in an olive effluent, FB, using thin layer chromatography (TLC) and High perfomance liquid chromatography (HPLC). Hydroxyphenyl acetic acid constitutes almost 60% of the organics in olive effluent FB. Five bacteria, namely RU-LV1; RU-FBI and RU-FB2; RU-SOI and RU-S02, were isolated from the olive effluents LV, FB and SO respectively. These isolates were found to be halotolerant and were able to grow over a broad temperature and pH range, with the maximum temperature and pH for growth being 28°C and pH 7 respectively. A range of microorganisms were evaluated for their ability to grow and reduce the total phenolic content of the olive effluents. Among these Neurospora crassa showed the highest potential for the biological reduction of total phenolics in olive effluents. Approximately 70% of the total phenolic content was removed by N. crassa. Trametes verscilor, Pseudomonas putida strains, RU-KMI and RU-KM3s, and the bacteria isolated from olive effluents could also degrade the total phenolic content of olive effluents, but to a lesser extent. The ability of the five bacterial isolates to grow and degrade aromatic compounds was assessed by growing them in medium with standard aromatic compounds. RU-L V1 degraded 96%, 100%, 73% and 100% of caffeic acid, protocatechuic acid, p-coumaric acid and vanillic acid respectively. The other isolates degraded caffeic acid and protocatechuic acid, but their ability to degraded p-coumaric acid and vanillic acid was found to be lesser than the ability of RU-LV1 to degrade the same aromatic compounds. Whole cells of RU-LV1 degraded vanillic acid but no metabolic products were observed on HPLC analysis. Resting cells, French pressed extract, cell free extracts and cell debris from RU-LV1 cells induced with vanillic acid degraded vanillic acid, ferulic acid and vanillin at rates higher than those obtained from non-induced cultures. No products were observed during the degradation of vanillic acid. Ferulic acid was converted into vanillic acid by French pressed extract, cell free extract and cell debris of RU-LV1. The maximum yield of vanillic acid as a product (0 .23 mM, 50 %yield) was obtained when cell free extracts of RU-LVI, grown in glucose and induced by vanillic acid, were used for the degradation of 0.4 mM ferulic acid. Vanillin was rapidly converted into vanillic acid by resting cells, cell free extracts and French pressed extract of RU-LVI. Using molecular techniques, the similarity ranking of the RU-LVI 16S rRNA gene and its clone showed a high similarity to Corynebacterium glutamicum and Corynebacterium acedopltilum. The rapid degradation of vanillin to vanillic acid suggests that extracts from RU-LV1 degrade ferulic acid into vanillin which is immediately oxidized to vanillic acid. Vanillic acid is also considered as a high value chemical. This project has a potential of producing useful chemicals from cheap substrates that can be found in olive effluents. , KMBT_363
- Full Text:
- Date Issued: 2002
- Authors: Notshe, Thandiwe Loretta
- Date: 2002
- Subjects: Phenols , Sewage -- Purification , Effluent quality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4078 , http://hdl.handle.net/10962/d1007446 , Phenols , Sewage -- Purification , Effluent quality
- Description: Olive mill wastewater is produced in large quantities during the production of olive oil and olive production effluents are produced during the processing of olives. This project was planned to find a use for constituents found in olive production wastewater. The task was carried out by first characterizing the olive effluents, then screening microorganisms for growth in the effluents and reduction of the pollutant properties of the effluents. An investigation into the biotransformation of aromatic compounds present in the effluents into useful chemicals, was carried out. The olive production effluents were collected from different stages in the process for treating olive wastewater, viz, a fermentation tank (FB), the surface of a digester (LV) and an evaporation pond (SO). The three effluents were characterized by investigating their phenolic composition. Protocatechuic acid, vanillic acid, syringic acid, hydroxyphenyl acetic acid, coumaric acid and ferulic acid were identified in an olive effluent, FB, using thin layer chromatography (TLC) and High perfomance liquid chromatography (HPLC). Hydroxyphenyl acetic acid constitutes almost 60% of the organics in olive effluent FB. Five bacteria, namely RU-LV1; RU-FBI and RU-FB2; RU-SOI and RU-S02, were isolated from the olive effluents LV, FB and SO respectively. These isolates were found to be halotolerant and were able to grow over a broad temperature and pH range, with the maximum temperature and pH for growth being 28°C and pH 7 respectively. A range of microorganisms were evaluated for their ability to grow and reduce the total phenolic content of the olive effluents. Among these Neurospora crassa showed the highest potential for the biological reduction of total phenolics in olive effluents. Approximately 70% of the total phenolic content was removed by N. crassa. Trametes verscilor, Pseudomonas putida strains, RU-KMI and RU-KM3s, and the bacteria isolated from olive effluents could also degrade the total phenolic content of olive effluents, but to a lesser extent. The ability of the five bacterial isolates to grow and degrade aromatic compounds was assessed by growing them in medium with standard aromatic compounds. RU-L V1 degraded 96%, 100%, 73% and 100% of caffeic acid, protocatechuic acid, p-coumaric acid and vanillic acid respectively. The other isolates degraded caffeic acid and protocatechuic acid, but their ability to degraded p-coumaric acid and vanillic acid was found to be lesser than the ability of RU-LV1 to degrade the same aromatic compounds. Whole cells of RU-LV1 degraded vanillic acid but no metabolic products were observed on HPLC analysis. Resting cells, French pressed extract, cell free extracts and cell debris from RU-LV1 cells induced with vanillic acid degraded vanillic acid, ferulic acid and vanillin at rates higher than those obtained from non-induced cultures. No products were observed during the degradation of vanillic acid. Ferulic acid was converted into vanillic acid by French pressed extract, cell free extract and cell debris of RU-LV1. The maximum yield of vanillic acid as a product (0 .23 mM, 50 %yield) was obtained when cell free extracts of RU-LVI, grown in glucose and induced by vanillic acid, were used for the degradation of 0.4 mM ferulic acid. Vanillin was rapidly converted into vanillic acid by resting cells, cell free extracts and French pressed extract of RU-LVI. Using molecular techniques, the similarity ranking of the RU-LVI 16S rRNA gene and its clone showed a high similarity to Corynebacterium glutamicum and Corynebacterium acedopltilum. The rapid degradation of vanillin to vanillic acid suggests that extracts from RU-LV1 degrade ferulic acid into vanillin which is immediately oxidized to vanillic acid. Vanillic acid is also considered as a high value chemical. This project has a potential of producing useful chemicals from cheap substrates that can be found in olive effluents. , KMBT_363
- Full Text:
- Date Issued: 2002
Gold exploration northeast of Ngundu Halt, northern marginal zone of the Limpopo Belt, Zimbabwe
- Authors: Simango, Robert Zulu
- Date: 2004 , 2013-05-30
- Subjects: Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5007 , http://hdl.handle.net/10962/d1005844 , Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Description: Gold exploration was conducted in northern margin, granulite-facies rocks of the Limpopo Belt. Methods used in the prospecting include drainage, soil and rock geochemistry, geophysical surveys, geological mapping, trenching and diamond drilling. These techniques successfully led to the discovery of two medium size, mesothermal gold deposits (Grid 2s and Grid 4). Objectives of this study were to (a) document the exploration methodology used; (b) describe the regional geology; (c) establish a mineral deposit model; (d) outline the methods and results of various exploration techniques; (e) outline follow-up procedures and evaluation of anomalies; and (f) discuss results of the exploration exercise and conclusions. The granulite-facies terrain comprises Charno-enderbites, mafic and felsic to intermediate metavolcanic rocks and meta-sediments. Renco Mine situated immediately east of the study area, was selected as the ore deposit model for the exploration program. Gold mineralization occurs in shear and thrust zones within an enderbite. The gold deposits are structurally controlled by a first-order, Sinistral transcrustal Mauch Shear Zone, which is parallel to a regional east-northeast penetrative foliation. The deposits are in dilation zones where the Mauch Shear (a) is intersected by a dextral east-west shear (Grid 2s), or (b) has a sinistral splay (Grid 4 and Renco). Close to these deposits, the Mauch Shear is in contact with a "greenstone belt", which is a possible source of crustal metamorphic ore fluids and gold. The Grid 2s deposit contains fine-grained, disseminated free gold, and small amounts of pyrrhotite, pyrite and chalcopyrite in quartz veins within third-order shears in K-feldspar granite. K-feldspar, sericitic, silicic, sulphidation and carbonate alteration characterizes the deposit, which has a proposed mantle-degassing model. The Grid 4 deposit is magmatic porphyry-type, with CuMo and Au in third- and fourth-order shears respectively. Mineralization comprises disseminated to semi-massive pyrrhotite, pyrite, chalcopyrite, sphalerite, bismuth, molybdenite and gold. Wall rock alteration includes biotitic, chloritic, silicic, sulphidation and carbonate. In Grid 2s, Grid 4 and Renco deposits, the alteration mineral assemblages are in three facies, which are granulite, amphibolte and greenschist. In the three deposits, the mineralization occurs with the amphibolite-facies, indicating post-peak, retrograde metamorphic conditions. , Illustrations (maps) only available in print form at Cory Library , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
- Authors: Simango, Robert Zulu
- Date: 2004 , 2013-05-30
- Subjects: Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5007 , http://hdl.handle.net/10962/d1005844 , Geology -- Zimbabwe , Gold ores -- Geology -- Zimbabwe , Greenstone belts -- Zimbabwe , Gold mines and mining -- Zimbabwe
- Description: Gold exploration was conducted in northern margin, granulite-facies rocks of the Limpopo Belt. Methods used in the prospecting include drainage, soil and rock geochemistry, geophysical surveys, geological mapping, trenching and diamond drilling. These techniques successfully led to the discovery of two medium size, mesothermal gold deposits (Grid 2s and Grid 4). Objectives of this study were to (a) document the exploration methodology used; (b) describe the regional geology; (c) establish a mineral deposit model; (d) outline the methods and results of various exploration techniques; (e) outline follow-up procedures and evaluation of anomalies; and (f) discuss results of the exploration exercise and conclusions. The granulite-facies terrain comprises Charno-enderbites, mafic and felsic to intermediate metavolcanic rocks and meta-sediments. Renco Mine situated immediately east of the study area, was selected as the ore deposit model for the exploration program. Gold mineralization occurs in shear and thrust zones within an enderbite. The gold deposits are structurally controlled by a first-order, Sinistral transcrustal Mauch Shear Zone, which is parallel to a regional east-northeast penetrative foliation. The deposits are in dilation zones where the Mauch Shear (a) is intersected by a dextral east-west shear (Grid 2s), or (b) has a sinistral splay (Grid 4 and Renco). Close to these deposits, the Mauch Shear is in contact with a "greenstone belt", which is a possible source of crustal metamorphic ore fluids and gold. The Grid 2s deposit contains fine-grained, disseminated free gold, and small amounts of pyrrhotite, pyrite and chalcopyrite in quartz veins within third-order shears in K-feldspar granite. K-feldspar, sericitic, silicic, sulphidation and carbonate alteration characterizes the deposit, which has a proposed mantle-degassing model. The Grid 4 deposit is magmatic porphyry-type, with CuMo and Au in third- and fourth-order shears respectively. Mineralization comprises disseminated to semi-massive pyrrhotite, pyrite, chalcopyrite, sphalerite, bismuth, molybdenite and gold. Wall rock alteration includes biotitic, chloritic, silicic, sulphidation and carbonate. In Grid 2s, Grid 4 and Renco deposits, the alteration mineral assemblages are in three facies, which are granulite, amphibolte and greenschist. In the three deposits, the mineralization occurs with the amphibolite-facies, indicating post-peak, retrograde metamorphic conditions. , Illustrations (maps) only available in print form at Cory Library , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
The sedimentology and depositional model of VS5 reef at Beatrix mine and surrounding areas of the Freestate Goldfield, South Africa
- Authors: Shivambu, Steven
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4942 , vital:20745
- Description: Historically, placers of economic importance at Sibanye Gold's Beatrix No. 3 Shaft were Beatrix Reef, Aandenk Reef and Composite of the two reefs. Recently, the VS5 placer has emerged to be a significant contributor of ore tonnages mined on the Shaft as mining advances into deeper levels towards the northern portion of the mine lease area. Gold concentration in the VS5 Reef is highly variable from uneconomic, through marginal to economic gold values. A good knowledge of the sedimentological framework of the VS5 Reef was considered necessary in order to interpret the variable distribution of the gold within the VS5 placer. The aim of this study was to determine the depositional environments that played a major role during the formation of the VS5 placer by means of investigating the macroscopic sedimentological parameters of this particular reef. These sedimentological parameters were used as the basis for the subdivision of VS5 Reef into different facies recognized in the mine and surrounding areas. It was recognized that the VS5 placer was formed in a distal, braided fluvial environment by the reworking of the pre-existing Aandenk Reef by new materials containing significant amount of nondurable materials (see definition on page xii) such as shale detritus. Where there is no evidence of reworking of the older Aandenk Reef, the VS5 Reef occurs as poorly sorted, polymictic conglomerate with abundance of non-durable detritus. This is referred to as the Immature (IV) VS5 facies and occurs in the northern portion of the study area. The degree of reworking of the gravel bars by waves and current action resulted in the formation of well sorted, oligomictic conglomerates of the Beatrix facies in the southern portion of the mine. At the boundaries between the Immature VS5 and Beatrix facies occurs the Transitional (Sub-mature) VS5 facies, characterized by reef comprising a polymictic upper portion and a basal more mature oligomictic unit. The Transitional VS5 facies extends across the current central northern mining faces of Beatrix No. 3 Shaft with a northwest-southeast trend. There is a strong correlation between the VS5 lithofacies and distribution of gold mineralization. The Immature VS5 facies is poorly mineralized, with gold values averaging 200 c.m.g/t and lower. The Transitional (Sub-mature) VS5 facies has elevated gold values, ranging from 300 c.m.g/t to 1500 cm.g/t. Mineralization in this unit tend to be bottom loaded as well as at the base of each cyclic unit. The Beatrix facies records the highest grades averaging >1500 cmg/t. The improved understanding of the VS5 lithofacies made it possible to predict gold mineralization and aid planning to mine into viable VS5 areas.
- Full Text:
- Date Issued: 2017
- Authors: Shivambu, Steven
- Date: 2017
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/4942 , vital:20745
- Description: Historically, placers of economic importance at Sibanye Gold's Beatrix No. 3 Shaft were Beatrix Reef, Aandenk Reef and Composite of the two reefs. Recently, the VS5 placer has emerged to be a significant contributor of ore tonnages mined on the Shaft as mining advances into deeper levels towards the northern portion of the mine lease area. Gold concentration in the VS5 Reef is highly variable from uneconomic, through marginal to economic gold values. A good knowledge of the sedimentological framework of the VS5 Reef was considered necessary in order to interpret the variable distribution of the gold within the VS5 placer. The aim of this study was to determine the depositional environments that played a major role during the formation of the VS5 placer by means of investigating the macroscopic sedimentological parameters of this particular reef. These sedimentological parameters were used as the basis for the subdivision of VS5 Reef into different facies recognized in the mine and surrounding areas. It was recognized that the VS5 placer was formed in a distal, braided fluvial environment by the reworking of the pre-existing Aandenk Reef by new materials containing significant amount of nondurable materials (see definition on page xii) such as shale detritus. Where there is no evidence of reworking of the older Aandenk Reef, the VS5 Reef occurs as poorly sorted, polymictic conglomerate with abundance of non-durable detritus. This is referred to as the Immature (IV) VS5 facies and occurs in the northern portion of the study area. The degree of reworking of the gravel bars by waves and current action resulted in the formation of well sorted, oligomictic conglomerates of the Beatrix facies in the southern portion of the mine. At the boundaries between the Immature VS5 and Beatrix facies occurs the Transitional (Sub-mature) VS5 facies, characterized by reef comprising a polymictic upper portion and a basal more mature oligomictic unit. The Transitional VS5 facies extends across the current central northern mining faces of Beatrix No. 3 Shaft with a northwest-southeast trend. There is a strong correlation between the VS5 lithofacies and distribution of gold mineralization. The Immature VS5 facies is poorly mineralized, with gold values averaging 200 c.m.g/t and lower. The Transitional (Sub-mature) VS5 facies has elevated gold values, ranging from 300 c.m.g/t to 1500 cm.g/t. Mineralization in this unit tend to be bottom loaded as well as at the base of each cyclic unit. The Beatrix facies records the highest grades averaging >1500 cmg/t. The improved understanding of the VS5 lithofacies made it possible to predict gold mineralization and aid planning to mine into viable VS5 areas.
- Full Text:
- Date Issued: 2017
A taxonomic study of Senecio speciosus, Senecio macrocephalus and possible hybrid populations using morphological data, toxicty tests and chromatography
- Authors: Lewis, Gillian Elizabeth
- Date: 1995
- Subjects: Senecio , Senecio -- Analysis , Shrimps , Artemia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4209 , http://hdl.handle.net/10962/d1003778
- Description: The variation between populations of Senecio speciosus Willd., Senecio macrocephalus DC. and intermediate plants was investigated in a comparative study of morphological characters, toxicity of plant extracts to brine shrimps (Artemia salina) and chromatography of plant extracts. Specimens were collected at 18 localities in the Eastern Cape Province. All these specimens were examined morphologically and chemical extracts were tested for toxicity and by comparative chromatography. The collection of Senecio speciosus and Senecio macrocephalus specimens in the Selmar Schonland Herbarium (GRA) was also examined morphologically. Six geographical areas were represented in the combined collections. Analysis of morphological data separated typical Senecio speciosus and Senecio macrocephalus at either end of hybrid index histograms and principal components analysis diagrams. The intermediate populations displayed morphological characters of both Senecio speciosus and Senecio macrocephalus. Some specimens were intermediate between these two species, falling within the range of variation of these species while others fell outside this range. The Brine Shrimp Assay was used to test for toxicity and to investigate the possibility of using toxicity data as a genetic marker in taxonomic studies. As Senecio speciosus extracts were less than 1% toxic and Senecio macrocephalus extracts were at least 95% toxic to the brine shrimps it is suggested that in this case toxicity can be used as a genetic marker. Toxicity can even be described as a good taxonomic character as discontinuity is very sudden and complete. The intermediate plants in the Grahamstown area were at least 92% toxic to the brine shrimps linking them to Senecio macrocephalus. Thin layer and paper chromatography were used as comparative techniques to study the chemical profiles of the specimens. Alkaloids, terpenoids and flavonoids were studied. Thin layer chromatography to separate the alkaloid components of the plant extracts showed Senecio speciosus and Senecio macrocephalus to have distinct chemical profiles suggesting that they are separate species. The intermediate plants- were found to contain chemical compounds matching either or both Senecio speciosus and Senecio macrocephalus suggesting that they may have arisen by hybridisation. In a preliminary investigation Senecio speciosus extracts showed a complete lack of terpenoid compounds whereas extracts from Senecio macrocephalus and the intermediate specimens tested gave a terpenoid colour reaction in the basal spot only. This links the intermediate populations with Senecio macrocephalus. Paper chromatography to separate the flavonoid constituents of the plant extracts also showed typical Senecio speciosus and Senecio macrocephalus to be distinct. The intermediate populations contained flavonoid compounds from one or both of these species. The populations in the Grahamstown area show morphological features close to and in some cases indistinguishable from Senecio speciosus. Chemically these specimens show some similarities with Senecio macrocephalus. In the East London area specimens show a similar mixture of characters but appear morphologically to be closer to Senecio macrocephalus. However, in the Amatole Mountains, despite both species being present in the same locality it appears that no hybridisation has occurred. It is therefore suggested that at some of the localities where the geographical ranges of Senecio speciosus and Senecio macrocephalus overlap in the Eastern Cape Province hybridisation between these two species occurs.
- Full Text:
- Date Issued: 1995
- Authors: Lewis, Gillian Elizabeth
- Date: 1995
- Subjects: Senecio , Senecio -- Analysis , Shrimps , Artemia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4209 , http://hdl.handle.net/10962/d1003778
- Description: The variation between populations of Senecio speciosus Willd., Senecio macrocephalus DC. and intermediate plants was investigated in a comparative study of morphological characters, toxicity of plant extracts to brine shrimps (Artemia salina) and chromatography of plant extracts. Specimens were collected at 18 localities in the Eastern Cape Province. All these specimens were examined morphologically and chemical extracts were tested for toxicity and by comparative chromatography. The collection of Senecio speciosus and Senecio macrocephalus specimens in the Selmar Schonland Herbarium (GRA) was also examined morphologically. Six geographical areas were represented in the combined collections. Analysis of morphological data separated typical Senecio speciosus and Senecio macrocephalus at either end of hybrid index histograms and principal components analysis diagrams. The intermediate populations displayed morphological characters of both Senecio speciosus and Senecio macrocephalus. Some specimens were intermediate between these two species, falling within the range of variation of these species while others fell outside this range. The Brine Shrimp Assay was used to test for toxicity and to investigate the possibility of using toxicity data as a genetic marker in taxonomic studies. As Senecio speciosus extracts were less than 1% toxic and Senecio macrocephalus extracts were at least 95% toxic to the brine shrimps it is suggested that in this case toxicity can be used as a genetic marker. Toxicity can even be described as a good taxonomic character as discontinuity is very sudden and complete. The intermediate plants in the Grahamstown area were at least 92% toxic to the brine shrimps linking them to Senecio macrocephalus. Thin layer and paper chromatography were used as comparative techniques to study the chemical profiles of the specimens. Alkaloids, terpenoids and flavonoids were studied. Thin layer chromatography to separate the alkaloid components of the plant extracts showed Senecio speciosus and Senecio macrocephalus to have distinct chemical profiles suggesting that they are separate species. The intermediate plants- were found to contain chemical compounds matching either or both Senecio speciosus and Senecio macrocephalus suggesting that they may have arisen by hybridisation. In a preliminary investigation Senecio speciosus extracts showed a complete lack of terpenoid compounds whereas extracts from Senecio macrocephalus and the intermediate specimens tested gave a terpenoid colour reaction in the basal spot only. This links the intermediate populations with Senecio macrocephalus. Paper chromatography to separate the flavonoid constituents of the plant extracts also showed typical Senecio speciosus and Senecio macrocephalus to be distinct. The intermediate populations contained flavonoid compounds from one or both of these species. The populations in the Grahamstown area show morphological features close to and in some cases indistinguishable from Senecio speciosus. Chemically these specimens show some similarities with Senecio macrocephalus. In the East London area specimens show a similar mixture of characters but appear morphologically to be closer to Senecio macrocephalus. However, in the Amatole Mountains, despite both species being present in the same locality it appears that no hybridisation has occurred. It is therefore suggested that at some of the localities where the geographical ranges of Senecio speciosus and Senecio macrocephalus overlap in the Eastern Cape Province hybridisation between these two species occurs.
- Full Text:
- Date Issued: 1995
A study of possible interactions between the pineal gland and the opioidergic system
- Authors: Khan, Razeeya B
- Date: 1990
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3729 , http://hdl.handle.net/10962/d1001468
- Description: Recent observations suggest a link between the pineal gland and the opioid system. Possible areas of interaction between the pineal gland and the opioidergic system in Wistar rats were investigated. The effect of opioids on the pineal gland in organ culture was monitored. Neither morphine, methadone nor the opioid antagonist naloxone was found to affect [¹⁴C]-serotonin metabolism by the pineal gland in vitro. Both the pineal gland and the opioid system are influenced by exposure to stressful stimuli. Morphine and melatonin had protective effects on stress-induced gastric lesions. The ability of melatonin to inhibit lesion formation was found not to be exerted via an opioidergic mechanism. Evidence has been obtained for a possible modulation of the stress response by the pineal gland . The opioid drugs are the most potent analgesic agents available. A possible interaction between the opioid system and the pineal gland in the modulation of the response to noxious stimuli was investigated. An intact pineal gland was found to be necessary for the manifestation of the nocturnally increased response of rats to noxious stimuli
- Full Text:
- Date Issued: 1990
- Authors: Khan, Razeeya B
- Date: 1990
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3729 , http://hdl.handle.net/10962/d1001468
- Description: Recent observations suggest a link between the pineal gland and the opioid system. Possible areas of interaction between the pineal gland and the opioidergic system in Wistar rats were investigated. The effect of opioids on the pineal gland in organ culture was monitored. Neither morphine, methadone nor the opioid antagonist naloxone was found to affect [¹⁴C]-serotonin metabolism by the pineal gland in vitro. Both the pineal gland and the opioid system are influenced by exposure to stressful stimuli. Morphine and melatonin had protective effects on stress-induced gastric lesions. The ability of melatonin to inhibit lesion formation was found not to be exerted via an opioidergic mechanism. Evidence has been obtained for a possible modulation of the stress response by the pineal gland . The opioid drugs are the most potent analgesic agents available. A possible interaction between the opioid system and the pineal gland in the modulation of the response to noxious stimuli was investigated. An intact pineal gland was found to be necessary for the manifestation of the nocturnally increased response of rats to noxious stimuli
- Full Text:
- Date Issued: 1990
An integration of reduction and logic for programming languages
- Authors: Wright, David A
- Date: 1988
- Subjects: Logic programming languages , Programming languages (Electronic computers)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4570 , http://hdl.handle.net/10962/d1002035
- Description: A new declarative language is presented which captures the expressibility of both logic programming languages and functional languages. This is achieved by conditional graph rewriting, with full unification as the parameter passing mechanism. The syntax and semantics are described both formally and informally, and examples are offered to support the expressibility claim made above. The language design is of further interest due to its uniformity and the inclusion of a novel mechanism for type inference in the presence of derived type hierarchies
- Full Text:
- Date Issued: 1988
- Authors: Wright, David A
- Date: 1988
- Subjects: Logic programming languages , Programming languages (Electronic computers)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4570 , http://hdl.handle.net/10962/d1002035
- Description: A new declarative language is presented which captures the expressibility of both logic programming languages and functional languages. This is achieved by conditional graph rewriting, with full unification as the parameter passing mechanism. The syntax and semantics are described both formally and informally, and examples are offered to support the expressibility claim made above. The language design is of further interest due to its uniformity and the inclusion of a novel mechanism for type inference in the presence of derived type hierarchies
- Full Text:
- Date Issued: 1988
The isolation of muscle activity and ground reaction force patterns associated with postural control in four load manipulation tasks
- Authors: Pettengell, Clare Louise
- Date: 2010
- Subjects: Physical fitness , Exercise , Materials handling , Manual work , Lifting and carrying
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5125 , http://hdl.handle.net/10962/d1005203 , Physical fitness , Exercise , Materials handling , Manual work , Lifting and carrying
- Description: Although much effort has been placed into the reduction of risks associated with manual materials handling, risk of musculoskeletal disorder development remains high. This may be due to the additional muscle activity necessary for the maintenance of postural equilibrium during work tasks. This research proposes that postural control and subsequent additional muscle activity is influenced by the magnitude of the external load and the degree of body movement. The objective of this research was to identify whether performing tasks with increased external load and with a greater degree of trunk motion places additional strain on the musculoskeletal system in excess of that imposed by task demands. Twenty-four male and twenty-four female subjects performed four load manipulation tasks under three loading conditions (0.8kg, 1.6kg, and 4kg). Each task comprised of a static and dynamic condition. For the static condition, subjects maintained a stipulated posture for ten seconds. The dynamic condition required subjects to move and replace a box once every three seconds, such that a complete lift and lower cycle was performed in six seconds. Throughout task completion, muscle activity of six pairs of trunk muscles were analysed using surface electromyography. This was accompanied by data regarding ground reaction forces obtained through the use of a force platform. After the completion of each condition subjects were required to identify and rate body discomfort. Differential analysis was used to isolate the muscle activity and ground reaction forces attributed to increased external load and increased trunk movement. It was found that the heaviest loading conditions (4kg) resulted in significantly greater (p<0.05) muscle activation in the majority of muscles during all tasks investigated. The trend of muscle activity attributed to load was similar in all significantly altered muscles and activation was greatest in the heaviest loading condition. A degree of movement efficiency occurred in some muscles when manipulating loads of 0.8kg and 1.6kg. At greater loads, this did not occur suggesting that heavier loading conditions result in additional strain on the body in excess of that imposed by task demands. In manipulated data, trend of vertical ground reaction forces increased with increased load in all tasks. Sagittal movement of the centre of pressure attributed to load was significantly affected in manipulated data in the second movement phase of the “hip shoulder” task and the second movement phase of the “hip twist” task. The “hip reach” task was most affected by increased load magnitude as muscle activity attributed to load was significantly different (p<0.05) under increased loading conditions in both movement phases in all muscles. Further, a significant interactional effect (p<0.05) between condition and data point was found in all muscles with the exception of the right and left lumbar erector spinae during the second movement phase of the “hip reach” task. Muscle activity associated with increased trunk motion resulted in additional strain on the trunk muscles in the “hip shoulder” and “hip reach” tasks as muscle activity associated with the static component of each of the above tasks was greater than that of the dynamic tasks. Trend of ground reaction forces attributed to increased trunk motion generally increased under increased loading conditions. Additionally, a significant interactional effect (p<0.05) between load and muscle activity pattern was found in all muscles during all tasks, with the exception of the right rectus abdominis in the first movement phase of the “hip shoulder’ task, the left rectus abdominis in the second movement phase of the “hip knee” task and the right latissimus dorsi during the first movement phase of the “hip twist” task. This was accompanied by a significant interactional effect (p<0.05) between load and sagittal centre of pressure movement attributed to load, in both movement phases of all tasks investigated. From this research it can be proposed that guidelines may underestimate risk and subsequently under predict the strain in tasks performed with greater external loads as well as tasks which require a greater degree of trunk motion. Therefore, this study illustrates the importance of the consideration of the muscle activity necessary to maintain postural equilibrium in overall load analyses.
- Full Text:
- Date Issued: 2010
- Authors: Pettengell, Clare Louise
- Date: 2010
- Subjects: Physical fitness , Exercise , Materials handling , Manual work , Lifting and carrying
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5125 , http://hdl.handle.net/10962/d1005203 , Physical fitness , Exercise , Materials handling , Manual work , Lifting and carrying
- Description: Although much effort has been placed into the reduction of risks associated with manual materials handling, risk of musculoskeletal disorder development remains high. This may be due to the additional muscle activity necessary for the maintenance of postural equilibrium during work tasks. This research proposes that postural control and subsequent additional muscle activity is influenced by the magnitude of the external load and the degree of body movement. The objective of this research was to identify whether performing tasks with increased external load and with a greater degree of trunk motion places additional strain on the musculoskeletal system in excess of that imposed by task demands. Twenty-four male and twenty-four female subjects performed four load manipulation tasks under three loading conditions (0.8kg, 1.6kg, and 4kg). Each task comprised of a static and dynamic condition. For the static condition, subjects maintained a stipulated posture for ten seconds. The dynamic condition required subjects to move and replace a box once every three seconds, such that a complete lift and lower cycle was performed in six seconds. Throughout task completion, muscle activity of six pairs of trunk muscles were analysed using surface electromyography. This was accompanied by data regarding ground reaction forces obtained through the use of a force platform. After the completion of each condition subjects were required to identify and rate body discomfort. Differential analysis was used to isolate the muscle activity and ground reaction forces attributed to increased external load and increased trunk movement. It was found that the heaviest loading conditions (4kg) resulted in significantly greater (p<0.05) muscle activation in the majority of muscles during all tasks investigated. The trend of muscle activity attributed to load was similar in all significantly altered muscles and activation was greatest in the heaviest loading condition. A degree of movement efficiency occurred in some muscles when manipulating loads of 0.8kg and 1.6kg. At greater loads, this did not occur suggesting that heavier loading conditions result in additional strain on the body in excess of that imposed by task demands. In manipulated data, trend of vertical ground reaction forces increased with increased load in all tasks. Sagittal movement of the centre of pressure attributed to load was significantly affected in manipulated data in the second movement phase of the “hip shoulder” task and the second movement phase of the “hip twist” task. The “hip reach” task was most affected by increased load magnitude as muscle activity attributed to load was significantly different (p<0.05) under increased loading conditions in both movement phases in all muscles. Further, a significant interactional effect (p<0.05) between condition and data point was found in all muscles with the exception of the right and left lumbar erector spinae during the second movement phase of the “hip reach” task. Muscle activity associated with increased trunk motion resulted in additional strain on the trunk muscles in the “hip shoulder” and “hip reach” tasks as muscle activity associated with the static component of each of the above tasks was greater than that of the dynamic tasks. Trend of ground reaction forces attributed to increased trunk motion generally increased under increased loading conditions. Additionally, a significant interactional effect (p<0.05) between load and muscle activity pattern was found in all muscles during all tasks, with the exception of the right rectus abdominis in the first movement phase of the “hip shoulder’ task, the left rectus abdominis in the second movement phase of the “hip knee” task and the right latissimus dorsi during the first movement phase of the “hip twist” task. This was accompanied by a significant interactional effect (p<0.05) between load and sagittal centre of pressure movement attributed to load, in both movement phases of all tasks investigated. From this research it can be proposed that guidelines may underestimate risk and subsequently under predict the strain in tasks performed with greater external loads as well as tasks which require a greater degree of trunk motion. Therefore, this study illustrates the importance of the consideration of the muscle activity necessary to maintain postural equilibrium in overall load analyses.
- Full Text:
- Date Issued: 2010
A contribution towards an understanding of the intensive tank culture of an ornamental Cichlid, Aulonocara Baenschi, from Chipoka, Lake Malawi
- Authors: Impson, N D (Neville Dean)
- Date: 1988
- Subjects: Cichlids -- Nysas, Lake , Cichlids -- Nyasa, Lake -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5208 , http://hdl.handle.net/10962/d1004596 , Cichlids -- Nysas, Lake , Cichlids -- Nyasa, Lake -- Physiology
- Description: The intensive tank culture of ornamental mouthbrooding cichlids poses several problems which limit their aquaculture potential. This project addressed some of these problems for Aulonocara baenschi. The production of juveniles in 2501 aquaria was accelerated when: a) aquaria were equipped with refuges, b) females of less than 70mm in standard length were used as broodstock, c) mouthbrooding females were replaced with gravid females at seven day intervals, and d) embryos were removed from the mouths of females at replacement times for artificial incubation. Two sex ratios also accelerated juvenile production. The sex ratio (male:females) 1:30 yielded the highest spawning returns per tank, and therefore represented the most effective utilization of aquarium space (a critical consideration for the small-scale culturist). Contrastingly, the sex ratio 1:12 yielded the highest clutch sizes and a high percentage female spawning return, and therefore represented the most effective utilization of broodstock (an important consideration for culturists inhibited by financial constraints or having an abundance of culture vessels). The reproductive behaviour of A. baenschi was described. Emphasis was given to aspects of reproduction of relevance to culture, for example; spawning times and seasons, clutch size and its relationship with female size, age and size of sexes at first spawning, embryo development rate and size of first swimming juveniles. The slow growth rate of juveniles, combined with a late attainment of marketable size (± seven months) was a major limitation affecting the cuIture potential of A. baenschi. Two factors favouring the cuIture of this species was the high survival rate recorded for both adults and juveniles, and the comparatively high prices fetched by fish on domestic wholesale markets (R4,00 per fish). It is recommended that A. baenschi should not be cultured exclusively for the relatively small South African ornamental fish market. A more profitable strategy for domestic culturists should involve a major production effort with A. baenschi and other desirable species of Aulonocara (e.g . A. ethelwynnae; A. hansbaenschi; A. stuartgranti & A. maylandi) for foreign markets (in particular, the U.S.A.; Western Europe & Japan). Not only are these markets massive, but prevailing exchange rates of the Rand with these currencies favour such a strategy.
- Full Text:
- Date Issued: 1988
- Authors: Impson, N D (Neville Dean)
- Date: 1988
- Subjects: Cichlids -- Nysas, Lake , Cichlids -- Nyasa, Lake -- Physiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5208 , http://hdl.handle.net/10962/d1004596 , Cichlids -- Nysas, Lake , Cichlids -- Nyasa, Lake -- Physiology
- Description: The intensive tank culture of ornamental mouthbrooding cichlids poses several problems which limit their aquaculture potential. This project addressed some of these problems for Aulonocara baenschi. The production of juveniles in 2501 aquaria was accelerated when: a) aquaria were equipped with refuges, b) females of less than 70mm in standard length were used as broodstock, c) mouthbrooding females were replaced with gravid females at seven day intervals, and d) embryos were removed from the mouths of females at replacement times for artificial incubation. Two sex ratios also accelerated juvenile production. The sex ratio (male:females) 1:30 yielded the highest spawning returns per tank, and therefore represented the most effective utilization of aquarium space (a critical consideration for the small-scale culturist). Contrastingly, the sex ratio 1:12 yielded the highest clutch sizes and a high percentage female spawning return, and therefore represented the most effective utilization of broodstock (an important consideration for culturists inhibited by financial constraints or having an abundance of culture vessels). The reproductive behaviour of A. baenschi was described. Emphasis was given to aspects of reproduction of relevance to culture, for example; spawning times and seasons, clutch size and its relationship with female size, age and size of sexes at first spawning, embryo development rate and size of first swimming juveniles. The slow growth rate of juveniles, combined with a late attainment of marketable size (± seven months) was a major limitation affecting the cuIture potential of A. baenschi. Two factors favouring the cuIture of this species was the high survival rate recorded for both adults and juveniles, and the comparatively high prices fetched by fish on domestic wholesale markets (R4,00 per fish). It is recommended that A. baenschi should not be cultured exclusively for the relatively small South African ornamental fish market. A more profitable strategy for domestic culturists should involve a major production effort with A. baenschi and other desirable species of Aulonocara (e.g . A. ethelwynnae; A. hansbaenschi; A. stuartgranti & A. maylandi) for foreign markets (in particular, the U.S.A.; Western Europe & Japan). Not only are these markets massive, but prevailing exchange rates of the Rand with these currencies favour such a strategy.
- Full Text:
- Date Issued: 1988
Parametrised gains for direction-dependent calibration
- Authors: Russeeaeon, Cyndie
- Date: 2021
- Subjects: Radio astronomy , Radio inferometers , Radio inferometers -- Calibration
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172400 , vital:42196
- Description: Calibration in radio interferometry describes the process of estimating and correcting for instrumental errors from data. Direction-Dependent (DD) calibration entails correcting for corruptions which vary across the sky. For small field of view observations, DD corruptions can be ignored but for wide fild observations, it is crucial to account for them. Traditional maximum likelihood calibration is not necessarily efficient in low signal-to-noise ratio (SNR) scenarios and this can lead to ovefitting. This can bias continuum subtraction and hence, restrict the spectral line studies. Since DD effects are expected to vary smoothly across the sky, the gains can be parametrised as a smooth function of the sky coordinates. Hence, we implement a solver where the atmosphere is modelled using a time-variant 2-dimensional phase screen with an arbitrary known frequency dependence. We assume arbitrary linear basis functions for the gains over the phase screen. The implemented solver is ptimised using the diagonal approximation of the Hessian as shown in previous studies. We present a few simulations to illustrate the performance of the solver.
- Full Text:
- Date Issued: 2021
- Authors: Russeeaeon, Cyndie
- Date: 2021
- Subjects: Radio astronomy , Radio inferometers , Radio inferometers -- Calibration
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172400 , vital:42196
- Description: Calibration in radio interferometry describes the process of estimating and correcting for instrumental errors from data. Direction-Dependent (DD) calibration entails correcting for corruptions which vary across the sky. For small field of view observations, DD corruptions can be ignored but for wide fild observations, it is crucial to account for them. Traditional maximum likelihood calibration is not necessarily efficient in low signal-to-noise ratio (SNR) scenarios and this can lead to ovefitting. This can bias continuum subtraction and hence, restrict the spectral line studies. Since DD effects are expected to vary smoothly across the sky, the gains can be parametrised as a smooth function of the sky coordinates. Hence, we implement a solver where the atmosphere is modelled using a time-variant 2-dimensional phase screen with an arbitrary known frequency dependence. We assume arbitrary linear basis functions for the gains over the phase screen. The implemented solver is ptimised using the diagonal approximation of the Hessian as shown in previous studies. We present a few simulations to illustrate the performance of the solver.
- Full Text:
- Date Issued: 2021
The Rhodes BioSure process in the treatment of acid mine drainage wastewaters
- Authors: Corbett, Christopher John
- Date: 2001 , 2013-05-03
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4077 , http://hdl.handle.net/10962/d1007405
- Description: While sulphate-enriched wastewaters are generated in a number of industrial processes, such as tanning, paper manufacture and metals processing, the principal contributors to large-scale pollution from this source in South Africa are the gold and coal mining industries. Both biological and physico-chemical processes, set in train by mining operations, give rise to the oxidation of sulphur species, and the resultant generation of AMD. The Vaal River system is most affected and receives large tonnages of mining related salinity as both direct discharges, and in diffuse runoff flows. The long-term burden of this problem, and sustaining ongoing treatment over the time-frames involved will almost certainly resort to the community inhabiting the area, notwithstanding progressive mine closure legislation and comprehensive regulation governing the polluterpays principle. The volume and time-frame of the AMD problem, and the need for a long-term and sustainable response has focused interest in biological treatment approaches. These have concentrated on active and passive treatment systems, both of which rely on microbial activity related to the biological sulphur cycle. Notwithstanding the reactor type, and the particular treatment approach used, widespread application of active AMD treatment has not yet been seen on any large scale. Singular factors constraining process development are bioreactor design, cost of bioreactor construction, and the cost of the carbon source and electron donor for the biological sulphate reduction process. The SRB are able to utilise only a limited range of small organic molecules. The studies reported here were motivated by the need to evaluate low-cost options and the treatment of high volume AMD flows. This has focussed research activity on bioprocess developments using complex organic compounds derived from waste streams as electron donor sources, and the integration of AMD treatment with other waste treatment objectives. The co-disposal of organic wastes with AMD treatment would enable the development of an 'integrated resource management' approach to the problem, including sustainability of treatment operations over the long time-frames involved. Apart from the cost advantages accrued to waste treatment, the recovery of the treated water as a resource to the wider community provides a potentially important value-added function to the combined operation. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2001
- Authors: Corbett, Christopher John
- Date: 2001 , 2013-05-03
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4077 , http://hdl.handle.net/10962/d1007405
- Description: While sulphate-enriched wastewaters are generated in a number of industrial processes, such as tanning, paper manufacture and metals processing, the principal contributors to large-scale pollution from this source in South Africa are the gold and coal mining industries. Both biological and physico-chemical processes, set in train by mining operations, give rise to the oxidation of sulphur species, and the resultant generation of AMD. The Vaal River system is most affected and receives large tonnages of mining related salinity as both direct discharges, and in diffuse runoff flows. The long-term burden of this problem, and sustaining ongoing treatment over the time-frames involved will almost certainly resort to the community inhabiting the area, notwithstanding progressive mine closure legislation and comprehensive regulation governing the polluterpays principle. The volume and time-frame of the AMD problem, and the need for a long-term and sustainable response has focused interest in biological treatment approaches. These have concentrated on active and passive treatment systems, both of which rely on microbial activity related to the biological sulphur cycle. Notwithstanding the reactor type, and the particular treatment approach used, widespread application of active AMD treatment has not yet been seen on any large scale. Singular factors constraining process development are bioreactor design, cost of bioreactor construction, and the cost of the carbon source and electron donor for the biological sulphate reduction process. The SRB are able to utilise only a limited range of small organic molecules. The studies reported here were motivated by the need to evaluate low-cost options and the treatment of high volume AMD flows. This has focussed research activity on bioprocess developments using complex organic compounds derived from waste streams as electron donor sources, and the integration of AMD treatment with other waste treatment objectives. The co-disposal of organic wastes with AMD treatment would enable the development of an 'integrated resource management' approach to the problem, including sustainability of treatment operations over the long time-frames involved. Apart from the cost advantages accrued to waste treatment, the recovery of the treated water as a resource to the wider community provides a potentially important value-added function to the combined operation. , KMBT_363 , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Date Issued: 2001
Studies on the fermentation of molasses by Clostridium acetobutylicum
- Authors: Barber, Jennifer Mary
- Date: 1978
- Subjects: Molasses , Clostridium acetobutylicum , Fermentation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4084 , http://hdl.handle.net/10962/d1007611 , Molasses , Clostridium acetobutylicum , Fermentation
- Description: The bacterium Clostridium acetobutylicum produces acetone and n [subscript] - butanol from molasses in an industrial fermentation system. Although the bacterium has been cultured in liquid media it does not grow well on agar plates and requires high concentrations of hydrogen. Pretreatment of agar plates with bovine catalase improves growth on agar media. The bacteria produce an area of clearing (halo) on Potato agar plates due to butyric acid (the precursor of n [subscript]-butanol) and ß -amylase production. This characteristic will be used as a plate screening assay for the selection of high solvent producing mutants. A laboratory scale fermentation system was developed and detailed studies including pH, turbidity and cell morphology changes, and the details of solvent production were undertaken. The fermentation was optimized for mutant selection. The production of normal solvent yields by isolated clones is required for the mutant selection programme. Studies revealed that sporulation of the clones increased their solvent yield although solvent yields were still lower than normal. Efficient sporulation is therefore a prerequisite for clone fermentation. The origin of the phage infection during the factory outbreak was determined and resistant clones obtained. The presence of a bacteriocin-like toxin causing decreases in turbidity was identified during the final fermentation stage. The strain sensitivity, optimum conditions for stability as well as the kinetics of inactivation and lethality have been investigated. Preliminary characterization and purification studies indicate the proteinaceous nature of the toxin. , KMBT_363
- Full Text:
- Date Issued: 1978
- Authors: Barber, Jennifer Mary
- Date: 1978
- Subjects: Molasses , Clostridium acetobutylicum , Fermentation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4084 , http://hdl.handle.net/10962/d1007611 , Molasses , Clostridium acetobutylicum , Fermentation
- Description: The bacterium Clostridium acetobutylicum produces acetone and n [subscript] - butanol from molasses in an industrial fermentation system. Although the bacterium has been cultured in liquid media it does not grow well on agar plates and requires high concentrations of hydrogen. Pretreatment of agar plates with bovine catalase improves growth on agar media. The bacteria produce an area of clearing (halo) on Potato agar plates due to butyric acid (the precursor of n [subscript]-butanol) and ß -amylase production. This characteristic will be used as a plate screening assay for the selection of high solvent producing mutants. A laboratory scale fermentation system was developed and detailed studies including pH, turbidity and cell morphology changes, and the details of solvent production were undertaken. The fermentation was optimized for mutant selection. The production of normal solvent yields by isolated clones is required for the mutant selection programme. Studies revealed that sporulation of the clones increased their solvent yield although solvent yields were still lower than normal. Efficient sporulation is therefore a prerequisite for clone fermentation. The origin of the phage infection during the factory outbreak was determined and resistant clones obtained. The presence of a bacteriocin-like toxin causing decreases in turbidity was identified during the final fermentation stage. The strain sensitivity, optimum conditions for stability as well as the kinetics of inactivation and lethality have been investigated. Preliminary characterization and purification studies indicate the proteinaceous nature of the toxin. , KMBT_363
- Full Text:
- Date Issued: 1978
Effects of small-scale water movement on the settlement and growth rates of the brown mussel Perna perna, on the south-east coast of South Africa
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
- Authors: Mathagu, Tendamudzimu Titus
- Date: 2003
- Subjects: Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5682 , http://hdl.handle.net/10962/d1005368 , Mussels -- South Africa , Perna -- South Africa , Perna -- Growth
- Description: The effects of small scale (cm) water movement on the settlement and growth rates of the brown mussel Perna perna were investigated on the south-east coast of South Africa (33°28′S, 27°10′E). L-shaped metal baffles attached to the substratum decreased the erosion rates of cement balls and it was concluded that the baffles decreased the water flow rate around cement balls. These L-shaped baffles were then used to decrease water flow rates around mussel patches and pot-scouring pads used as artificial substrata for the settlement of P.perna larvae. Anova indicated that settlement rate varied by date and site while decreased water flow rate significantly increased larval settlement (p<0.05), only on the site and day that had the overall highest number of settlers. Mussels in the low zone had significantly higher growth rates than those in the high zone. Decreased water flow rate significantly increased mussel growth rate in the lower zone (Anova, p<0.05), while it did not have a significant effect on the mussel in the high zone. Thus water flow manipulation increased growth rates in the zone, which already had high growth rate. It was concluded that small-scale (cm) water flow patterns have an effect on both Perna perna settlement and growth rates, but only under specific conditions. Larval settlement rate was significantly increased by water flow manipulation on the site and day that had the highest number of settlers. Growth rates were significantly increased by decreased water flow rate only in the low zone, where growth rates are the highest. Although water flow was manipulated in both zones its effect in the high zone was insignificant (Anova) compared to other factors affecting growth rates at this tidal level.
- Full Text:
- Date Issued: 2003
The natural history of the humpback dolphin, Sousa chinensis, in KwaZulu-Natal, South Africa : age, growth and reproduction
- Authors: Nolte, Zianca
- Date: 2014
- Subjects: Sousa -- South Africa -- KwaZulu-Natal , Dolphins -- Behavior -- South Africa -- KwaZulu-Natal , Dolphins -- Age determination -- South Africa -- KwaZulu-Natal , Dolphins -- Development -- South Africa -- KwaZulu-Natal , Dolphins -- South Africa -- KwaZulu-Natal -- Reproduction , Dolphins -- Physiology -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5878 , http://hdl.handle.net/10962/d1013178
- Description: Globally, inshore cetaceans are being threatened by a number of anthropogenic activities. The Indo-Pacific humpback dolphin, Sousa chinensis, is currently listed as ‘near threatened’ by the International Union for the Conservation of Nature (IUCN). In order to be able to advise on management and conservation strategies, knowledge on the life history of the species is required. To date very little is known about the biology of humpback dolphins. The aim of the present study was to determine basic life history parameters, including age, growth and reproduction of humpback dolphins incidentally caught in shark nets. Age was estimated by counting the growth layer groups (GLGs) in the dentine and cementum of sectioned and stained teeth. Both a Von Bertalanffy and a Gompertz growth curve fitted well to the data, but for comparison with previous studies on Sousa, the Gompertz growth function was adopted to describe the relationship between length and age for KwaZulu-Natal populations. Length at birth was estimated between 104.33 and 111.57 cm for males and females, respectively. Asymptotic length was reached at 266.48 cm and 239.29 cm for males and females, respectively. This corresponds to the attainment of physical maturity at 24 GLGs in males and 16 GLGs in females. Asymptotic mass for males could not be determined, while for females it occurred around 160 kg. The maximum age estimates and recorded lengths were 24 GLGs and 279 cm for males and 17.7 GLGs and 249 cm for females. Differences in length-at-age and mass-at-age for S. chinensis suggest sexual dimorphism. The attainment of sexual maturity in males occurred between 9 and 10 GLGs, corresponding to 230 cm total body length and 140 kg. The maximum combined testis mass of mature males comprised 0.42% of total body mass, and a roving male mating system was proposed. In females, sexual maturity occurred around 7.6 GLG, between 220 and 222 cm and 104 - 140 kg. The ovulation rate is estimated at 0.2 ovulations per annum, suggesting a calving interval of five years. It is evident from the results obtained in the present study that geographical differences exist in the life history parameters of S. chinensis. As a result, regional conservation and management strategies are imperative. Results from this study can therefore assist in assessing the status of existing population structures in the KwaZulu-Natal coastal waters, and the implementation of regional mitigation strategies to ensure the continued survival of humpback dolphins in the region.
- Full Text:
- Date Issued: 2014
- Authors: Nolte, Zianca
- Date: 2014
- Subjects: Sousa -- South Africa -- KwaZulu-Natal , Dolphins -- Behavior -- South Africa -- KwaZulu-Natal , Dolphins -- Age determination -- South Africa -- KwaZulu-Natal , Dolphins -- Development -- South Africa -- KwaZulu-Natal , Dolphins -- South Africa -- KwaZulu-Natal -- Reproduction , Dolphins -- Physiology -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5878 , http://hdl.handle.net/10962/d1013178
- Description: Globally, inshore cetaceans are being threatened by a number of anthropogenic activities. The Indo-Pacific humpback dolphin, Sousa chinensis, is currently listed as ‘near threatened’ by the International Union for the Conservation of Nature (IUCN). In order to be able to advise on management and conservation strategies, knowledge on the life history of the species is required. To date very little is known about the biology of humpback dolphins. The aim of the present study was to determine basic life history parameters, including age, growth and reproduction of humpback dolphins incidentally caught in shark nets. Age was estimated by counting the growth layer groups (GLGs) in the dentine and cementum of sectioned and stained teeth. Both a Von Bertalanffy and a Gompertz growth curve fitted well to the data, but for comparison with previous studies on Sousa, the Gompertz growth function was adopted to describe the relationship between length and age for KwaZulu-Natal populations. Length at birth was estimated between 104.33 and 111.57 cm for males and females, respectively. Asymptotic length was reached at 266.48 cm and 239.29 cm for males and females, respectively. This corresponds to the attainment of physical maturity at 24 GLGs in males and 16 GLGs in females. Asymptotic mass for males could not be determined, while for females it occurred around 160 kg. The maximum age estimates and recorded lengths were 24 GLGs and 279 cm for males and 17.7 GLGs and 249 cm for females. Differences in length-at-age and mass-at-age for S. chinensis suggest sexual dimorphism. The attainment of sexual maturity in males occurred between 9 and 10 GLGs, corresponding to 230 cm total body length and 140 kg. The maximum combined testis mass of mature males comprised 0.42% of total body mass, and a roving male mating system was proposed. In females, sexual maturity occurred around 7.6 GLG, between 220 and 222 cm and 104 - 140 kg. The ovulation rate is estimated at 0.2 ovulations per annum, suggesting a calving interval of five years. It is evident from the results obtained in the present study that geographical differences exist in the life history parameters of S. chinensis. As a result, regional conservation and management strategies are imperative. Results from this study can therefore assist in assessing the status of existing population structures in the KwaZulu-Natal coastal waters, and the implementation of regional mitigation strategies to ensure the continued survival of humpback dolphins in the region.
- Full Text:
- Date Issued: 2014
The use of remote sensing and Geographic Information System (GIS) techniques, to interpret savanna ecosystem patterns in the Sabi Sand Game Reserve, Mpumalanga province
- Fortescue, Alexander Kenneth John
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
- Authors: Fortescue, Alexander Kenneth John
- Date: 1997
- Subjects: Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4857 , http://hdl.handle.net/10962/d1005533 , Sabi-Sand Game Reserve (South Africa) , Savanna ecology -- South Africa -- Mpumalanga , Geographic information systems , Savanna ecology -- Remote sensing
- Description: This thesis explores techniques which ultimately strive to optimize production systems in rangeland areas of southern Africa. By linking spatially significant, satellite derived data to practical measurements of vegetation structure, valuable insight has been derived on processes of ecosystem function, in the Sabi Sand Game Reserve. A broad ecosystem response mechanism has been established from a conventional Normalized Differentiation Vegetation Index (NDVI). By responding to increases in production, which are driven by disturbance, this index has allowed quantitative systems theory in savanna to be tested and refined. Methods of biomass and production estimation which are specifically designed to reduce the cost and time involved with the more conventional method of destructive harvesting have been tested in the savanna at the Sabi Sand Game Reserve. Results from these estimates relate well with data derived through destructive harvesting in structurally similar savanna. Moreover, by relating the above-ground woody production estimates to remere sensing indices, it was possible to demonstrate that the problem of extrapolation, universal to most biomass and production studies can be overcome. Since remote sensing encompasses an array of tools fundamental to rangeland inventory, monitoring and management, valuable spatially significant information pertaining to ecosystem structure and function has been provided for managers in the Sabi Sand Game Reserve.
- Full Text:
- Date Issued: 1997
The ichthyofauna and piscivorous avifauna in a small temporarily open/closed Eastern Cape estuary, South Africa
- Authors: Blake, Justin David
- Date: 2010
- Subjects: Estuarine fishes -- South Africa -- Eastern Cape , Bird populations -- South Africa -- Riet River Estuary , Estuaries -- South Africa -- Eastern Cape , Fish populations -- South Africa -- Riet River Estuary , Estuarine animals -- South Africa -- Riet River Estuary , Birds -- South Africa -- Riet River Estuary , Riet River Estuary (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5709 , http://hdl.handle.net/10962/d1005395 , Estuarine fishes -- South Africa -- Eastern Cape , Bird populations -- South Africa -- Riet River Estuary , Estuaries -- South Africa -- Eastern Cape , Fish populations -- South Africa -- Riet River Estuary , Estuarine animals -- South Africa -- Riet River Estuary , Birds -- South Africa -- Riet River Estuary , Riet River Estuary (South Africa)
- Description: The spatial and temporal patterns in selected components of the ichthyofauna and piscivorous avifauna in the small temporarily open/closed Riet River Estuary located on the eastern seaboard of southern Africa was investigated monthly over the period August 2005 to July 2006. The ichthyofauna within the littoral zone of the estuary was sampled using a 5 m seine net (8 stations) while a 30 m seine net (4 stations) was employed to sample the fish in the channel. Bird counts were made along repeat transects along the length of the estuary. Total ichthyofaunal abundances and biomass ranged between 1.60 and 8.67 individuals m⁻² and 0.45 to 21.76 g wwt m⁻² within the littoral zone, and between 0.08 and 0.44 individuals m⁻² and 0.58 and 36.52 g wwt m⁻² in the channel of the estuary. The highest values were generally recorded during the summer months. Results of the numerical analysis indicated that the breaching events recorded over the study period did not lead to a common trend in the ichthyofaunal community. In the absence of a link to the marine environment, the ichthyofaunal community in the littoral zone was numerically dominated by the estuarine resident species, Gilchristella aestuaria and to a lesser extent by Glossogobius callidus, which collectively accounted for ca. 54% of the total ichthyofauna sampled. The establishment of a link to the marine environment coincided with increased numbers of marine breeding species including Atherina breviceps and Rhabdosargus holubi to total fish counts within the estuary. Hierarchical cluster analysis did not identify any spatial patterns in the community structure of the ichthyofauna in the littoral zone or channel zone of the estuary, which could likely be linked to the absence of any distinct horizontal patterns in salinity and temperature within the system. A total of thirteen piscivorous bird species was recorded over the study period. Of the recorded species, six species were wading piscivores, four species were aerial divers and the remaining three species were pursuit swimmers. There were no significant correlations between the estimates of the ichthyofaunal abundance and biomass and bird numbers evident during the study (P> 0.05 in both cases). The Reed Cormorant (Phalacrocorax africanus) was the dominant species throughout the study, with a mean of 8.25 (SD ± 7.90) individuals per count. Mean values of the Pied Kingfisher (Ceryle rudis) and Giant Kingfisher (Megaceryle maximus) were 3.42 (SD ± 1.20) and 1.17 (SD ± 0.60) individuals per count, respectively. The remaining species revealed mean values < 0.5 individuals per count. The highest bird numbers were recorded in winter reflecting the migration of large numbers of the Reed Cormorant into the system. Breaching events were associated with a decrease in total bird numbers, which was most likely due to loss of potential foraging habitat (littoral zone) for waders resulting from reduced water levels. Monthly food consumption by all piscivorous birds revealed large temporal variability, ranging from 26.35 to 140.58 kg per month. The observed variability could be linked to mouth phase and bird numbers.
- Full Text:
- Date Issued: 2010
- Authors: Blake, Justin David
- Date: 2010
- Subjects: Estuarine fishes -- South Africa -- Eastern Cape , Bird populations -- South Africa -- Riet River Estuary , Estuaries -- South Africa -- Eastern Cape , Fish populations -- South Africa -- Riet River Estuary , Estuarine animals -- South Africa -- Riet River Estuary , Birds -- South Africa -- Riet River Estuary , Riet River Estuary (South Africa)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5709 , http://hdl.handle.net/10962/d1005395 , Estuarine fishes -- South Africa -- Eastern Cape , Bird populations -- South Africa -- Riet River Estuary , Estuaries -- South Africa -- Eastern Cape , Fish populations -- South Africa -- Riet River Estuary , Estuarine animals -- South Africa -- Riet River Estuary , Birds -- South Africa -- Riet River Estuary , Riet River Estuary (South Africa)
- Description: The spatial and temporal patterns in selected components of the ichthyofauna and piscivorous avifauna in the small temporarily open/closed Riet River Estuary located on the eastern seaboard of southern Africa was investigated monthly over the period August 2005 to July 2006. The ichthyofauna within the littoral zone of the estuary was sampled using a 5 m seine net (8 stations) while a 30 m seine net (4 stations) was employed to sample the fish in the channel. Bird counts were made along repeat transects along the length of the estuary. Total ichthyofaunal abundances and biomass ranged between 1.60 and 8.67 individuals m⁻² and 0.45 to 21.76 g wwt m⁻² within the littoral zone, and between 0.08 and 0.44 individuals m⁻² and 0.58 and 36.52 g wwt m⁻² in the channel of the estuary. The highest values were generally recorded during the summer months. Results of the numerical analysis indicated that the breaching events recorded over the study period did not lead to a common trend in the ichthyofaunal community. In the absence of a link to the marine environment, the ichthyofaunal community in the littoral zone was numerically dominated by the estuarine resident species, Gilchristella aestuaria and to a lesser extent by Glossogobius callidus, which collectively accounted for ca. 54% of the total ichthyofauna sampled. The establishment of a link to the marine environment coincided with increased numbers of marine breeding species including Atherina breviceps and Rhabdosargus holubi to total fish counts within the estuary. Hierarchical cluster analysis did not identify any spatial patterns in the community structure of the ichthyofauna in the littoral zone or channel zone of the estuary, which could likely be linked to the absence of any distinct horizontal patterns in salinity and temperature within the system. A total of thirteen piscivorous bird species was recorded over the study period. Of the recorded species, six species were wading piscivores, four species were aerial divers and the remaining three species were pursuit swimmers. There were no significant correlations between the estimates of the ichthyofaunal abundance and biomass and bird numbers evident during the study (P> 0.05 in both cases). The Reed Cormorant (Phalacrocorax africanus) was the dominant species throughout the study, with a mean of 8.25 (SD ± 7.90) individuals per count. Mean values of the Pied Kingfisher (Ceryle rudis) and Giant Kingfisher (Megaceryle maximus) were 3.42 (SD ± 1.20) and 1.17 (SD ± 0.60) individuals per count, respectively. The remaining species revealed mean values < 0.5 individuals per count. The highest bird numbers were recorded in winter reflecting the migration of large numbers of the Reed Cormorant into the system. Breaching events were associated with a decrease in total bird numbers, which was most likely due to loss of potential foraging habitat (littoral zone) for waders resulting from reduced water levels. Monthly food consumption by all piscivorous birds revealed large temporal variability, ranging from 26.35 to 140.58 kg per month. The observed variability could be linked to mouth phase and bird numbers.
- Full Text:
- Date Issued: 2010
Accelerated implementations of the RIME for DDE calibration and source modelling
- Authors: Van Staden, Joshua
- Date: 2021
- Subjects: Radio astronomy , Radio inferometers , Radio inferometers -- Calibration , Radio astronomy -- Data processing , Radio inferometers -- Data processing , Radio inferometers -- Calibration -- Data processing
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172422 , vital:42199
- Description: Second- and third-generation calibration methods filter out subtle effects in interferometer data, and therefore yield significantly higher dynamic ranges. The basis of these calibration techniques relies on building a model of the sky and corrupting it with models of the effects acting on the sources. The sensitivities of modern instruments call for more elaborate models to capture the level of detail that is required to achieve accurate calibration. This thesis implements two types of models to be used in for second- and third-generation calibration. The first model implemented is shapelets, which can be used to model radio source morphologies directly in uv space. The second model implemented is Zernike polynomials, which can be used to represent the primary beam of the antenna. We implement these models in the CODEX-AFRICANUS package and provide a set of unit tests for each model. Additionally, we compare our implementations against other methods of representing these objects and instrumental effects, namely NIFTY-GRIDDER against shapelets and a FITS-interpolation method against the Zernike polynomials. We find that to achieve sufficient accuracy, our implementation of the shapelet model has a higher runtime to that of the NIFTY-GRIDDER. However, the NIFTY-GRIDDER cannot simulate a component-based sky model while the shapelet model can. Additionally, the shapelet model is fully parametric, which allows for integration into a parameterised solver. We find that, while having a smaller memory footprint, our Zernike model has a greater computational complexity than that of the FITS-interpolated method. However, we find that the Zernike implementation has floating-point accuracy in its modelling, while the FITS-interpolated model loses some accuracy through the discretisation of the beam.
- Full Text:
- Date Issued: 2021
- Authors: Van Staden, Joshua
- Date: 2021
- Subjects: Radio astronomy , Radio inferometers , Radio inferometers -- Calibration , Radio astronomy -- Data processing , Radio inferometers -- Data processing , Radio inferometers -- Calibration -- Data processing
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/172422 , vital:42199
- Description: Second- and third-generation calibration methods filter out subtle effects in interferometer data, and therefore yield significantly higher dynamic ranges. The basis of these calibration techniques relies on building a model of the sky and corrupting it with models of the effects acting on the sources. The sensitivities of modern instruments call for more elaborate models to capture the level of detail that is required to achieve accurate calibration. This thesis implements two types of models to be used in for second- and third-generation calibration. The first model implemented is shapelets, which can be used to model radio source morphologies directly in uv space. The second model implemented is Zernike polynomials, which can be used to represent the primary beam of the antenna. We implement these models in the CODEX-AFRICANUS package and provide a set of unit tests for each model. Additionally, we compare our implementations against other methods of representing these objects and instrumental effects, namely NIFTY-GRIDDER against shapelets and a FITS-interpolation method against the Zernike polynomials. We find that to achieve sufficient accuracy, our implementation of the shapelet model has a higher runtime to that of the NIFTY-GRIDDER. However, the NIFTY-GRIDDER cannot simulate a component-based sky model while the shapelet model can. Additionally, the shapelet model is fully parametric, which allows for integration into a parameterised solver. We find that, while having a smaller memory footprint, our Zernike model has a greater computational complexity than that of the FITS-interpolated method. However, we find that the Zernike implementation has floating-point accuracy in its modelling, while the FITS-interpolated model loses some accuracy through the discretisation of the beam.
- Full Text:
- Date Issued: 2021
Biology and ecology of Glossogobius callidus (Smith 1937) in irrigation impoundments in the Sundays River Valley of the Eastern Cape
- Authors: Mofu, Lubabalo
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1136 , vital:20023
- Description: The River Goby Glossogobius callidus (Smith, 1937) is a native abundant fish in both freshwater and estuarine habitats in the Cape Fold Ecoregion, yet little information is available on its life-history. This study aims to contribute to knowledge on the age and growth, reproductive biology and the diet and feeding habits of G. callidus in irrigation impoundments. Glossogobius callidus was sampled monthly from August 2013 till March 2015; from the irrigation ponds in the Sundays River Valley, Eastern Cape Province, South Africa. To determine sex, gonads were visually assessed under a dissecting microscope to confirm the sex based on the shape of the urogenital papillae. Fish were then dissected to confirm sex and gonads were categorised into five macroscopic stages which were histologically validated. Microscopic stages of gonadal development were discerned based on nuclear and cytoplasmic characteristics of the oocyte or sperm. Ovaries and sperms were assigned stages based on the most advanced type of oocyte present. In total 2054 fishes ranging in length from 21.1 mm to 137.2 mm TL were sampled. The sex ratio (1.1 males: 1 females) did not differ from unity (x2 = 0.027, df = 1, p = 0.87). Length at 50% maturity (Lm) was 70 mm TL females and 72 mm TL for males. Spawning season was mid-spring and mid-summer and mean ± S.D absolute fecundity was estimated at 1028.2 ± 131.7 ova/fish. Relative fecundity (number of vitellogenic oocytes per gram of eviscerated fish mass) were estimated at 50 ± 18 ova/fish gram. Otoliths from 560 fish were used for ageing. Growth zone deposition rate was validated using edge analysis. As a unimodal periodic regression model best described the temporal proportion of opaque zone deposition on the edge of otoliths over a one-year period, growth zone deposition rate was validated as annual. The oldest female fish was a 4-year old 84.4 mm TL fish and the oldest male was a 7-year old 100.5 mm TL fish. The length-at-age for the entire population of 560 G. callidus provided von Bertalanffy parameters of Lt = 92 (1 - e -0.58(t + 0.4)) mm TL for the entire population, Lt = 70 (1 - e -1.8 (t + 0.06)) mm TL for males and Lt = 65 (1 - e -1.8 (t + 0.05)) mm TL for females. Converting length at maturity to age at maturity demonstrated that G. callidus attained maturity at an age of 2-years. Growth performance described using the phi-prime index showed that G. callidus had lower growth performance compared to the invasive Neogobius melanostomus. Using age structure, natural mortality was estimated at 1.31 yr-1 using catch curve analysis. Diet of G. callidus comprised of ten taxonomic groups. Among these, aquatic invertebrates were the most diverse group but while relative contribution of the dietary components varied across all size classes and seasons, the key prey items were consistently found in all size classes. These were Diptera, Hemiptera, Trichoptera, Odonata, Cladocera, Copepoda, Hydracarina, Amphipoda, Crustacea, and Mollusca. While dietary differences were observed between the size classes and throughout the seasons, G. callidus can be regarded as a generalist feeder preying on an array of different species. Given its abundance and diet, I suggest that G. callidus contribute considerably to the invertebrate predation pressure in these artificial aquatic environments in an arid region. In summary, medium fecundity, fast growth, moderate maturity, and a generalist feeding behaviour demonstrate that G. callidus is an equilibrium life strategist. In comparison with other species, the life-history traits of G. callidus from irrigation impoundments resemble those of other freshwater goby species, some of which are global invaders.
- Full Text:
- Date Issued: 2016
- Authors: Mofu, Lubabalo
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/1136 , vital:20023
- Description: The River Goby Glossogobius callidus (Smith, 1937) is a native abundant fish in both freshwater and estuarine habitats in the Cape Fold Ecoregion, yet little information is available on its life-history. This study aims to contribute to knowledge on the age and growth, reproductive biology and the diet and feeding habits of G. callidus in irrigation impoundments. Glossogobius callidus was sampled monthly from August 2013 till March 2015; from the irrigation ponds in the Sundays River Valley, Eastern Cape Province, South Africa. To determine sex, gonads were visually assessed under a dissecting microscope to confirm the sex based on the shape of the urogenital papillae. Fish were then dissected to confirm sex and gonads were categorised into five macroscopic stages which were histologically validated. Microscopic stages of gonadal development were discerned based on nuclear and cytoplasmic characteristics of the oocyte or sperm. Ovaries and sperms were assigned stages based on the most advanced type of oocyte present. In total 2054 fishes ranging in length from 21.1 mm to 137.2 mm TL were sampled. The sex ratio (1.1 males: 1 females) did not differ from unity (x2 = 0.027, df = 1, p = 0.87). Length at 50% maturity (Lm) was 70 mm TL females and 72 mm TL for males. Spawning season was mid-spring and mid-summer and mean ± S.D absolute fecundity was estimated at 1028.2 ± 131.7 ova/fish. Relative fecundity (number of vitellogenic oocytes per gram of eviscerated fish mass) were estimated at 50 ± 18 ova/fish gram. Otoliths from 560 fish were used for ageing. Growth zone deposition rate was validated using edge analysis. As a unimodal periodic regression model best described the temporal proportion of opaque zone deposition on the edge of otoliths over a one-year period, growth zone deposition rate was validated as annual. The oldest female fish was a 4-year old 84.4 mm TL fish and the oldest male was a 7-year old 100.5 mm TL fish. The length-at-age for the entire population of 560 G. callidus provided von Bertalanffy parameters of Lt = 92 (1 - e -0.58(t + 0.4)) mm TL for the entire population, Lt = 70 (1 - e -1.8 (t + 0.06)) mm TL for males and Lt = 65 (1 - e -1.8 (t + 0.05)) mm TL for females. Converting length at maturity to age at maturity demonstrated that G. callidus attained maturity at an age of 2-years. Growth performance described using the phi-prime index showed that G. callidus had lower growth performance compared to the invasive Neogobius melanostomus. Using age structure, natural mortality was estimated at 1.31 yr-1 using catch curve analysis. Diet of G. callidus comprised of ten taxonomic groups. Among these, aquatic invertebrates were the most diverse group but while relative contribution of the dietary components varied across all size classes and seasons, the key prey items were consistently found in all size classes. These were Diptera, Hemiptera, Trichoptera, Odonata, Cladocera, Copepoda, Hydracarina, Amphipoda, Crustacea, and Mollusca. While dietary differences were observed between the size classes and throughout the seasons, G. callidus can be regarded as a generalist feeder preying on an array of different species. Given its abundance and diet, I suggest that G. callidus contribute considerably to the invertebrate predation pressure in these artificial aquatic environments in an arid region. In summary, medium fecundity, fast growth, moderate maturity, and a generalist feeding behaviour demonstrate that G. callidus is an equilibrium life strategist. In comparison with other species, the life-history traits of G. callidus from irrigation impoundments resemble those of other freshwater goby species, some of which are global invaders.
- Full Text:
- Date Issued: 2016
Categorising Network Telescope data using big data enrichment techniques
- Authors: Davis, Michael Reginald
- Date: 2019
- Subjects: Denial of service attacks , Big data , Computer networks -- Security measures
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92941 , vital:30766
- Description: Network Telescopes, Internet backbone sampling, IDS and other forms of network-sourced Threat Intelligence provide researchers with insight into the methods and intent of remote entities by capturing network traffic and analysing the resulting data. This analysis and determination of intent is made difficult by the large amounts of potentially malicious traffic, coupled with limited amount of knowledge that can be attributed to the source of the incoming data, as the source is known only by its IP address. Due to the lack of commonly available tooling, many researchers start this analysis from the beginning and so repeat and re-iterate previous research as the bulk of their work. As a result new insight into methods and approaches of analysis is gained at a high cost. Our research approaches this problem by using additional knowledge about the source IP address such as open ports, reverse and forward DNS, BGP routing tables and more, to enhance the researcher's ability to understand the traffic source. The research is a BigData experiment, where large (hundreds of GB) datasets are merged with a two month section of Network Telescope data using a set of Python scripts. The result are written to a Google BigQuery database table. Analysis of the network data is greatly simplified, with questions about the nature of the source, such as its device class (home routing device or server), potential vulnerabilities (open telnet ports or databases) and location becoming relatively easy to answer. Using this approach, researchers can focus on the questions that need answering and efficiently address them. This research could be taken further by using additional data sources such as Geo-location, WHOIS lookups, Threat Intelligence feeds and many others. Other potential areas of research include real-time categorisation of incoming packets, in order to better inform alerting and reporting systems' configuration. In conclusion, categorising Network Telescope data in this way provides insight into the intent of the (apparent) originator and as such is a valuable tool for those seeking to understand the purpose and intent of arriving packets. In particular, the ability to remove packets categorised as non-malicious (e.g. those in the Research category) from the data eliminates a known source of `noise' from the data. This allows the researcher to focus their efforts in a more productive manner.
- Full Text:
- Date Issued: 2019
- Authors: Davis, Michael Reginald
- Date: 2019
- Subjects: Denial of service attacks , Big data , Computer networks -- Security measures
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92941 , vital:30766
- Description: Network Telescopes, Internet backbone sampling, IDS and other forms of network-sourced Threat Intelligence provide researchers with insight into the methods and intent of remote entities by capturing network traffic and analysing the resulting data. This analysis and determination of intent is made difficult by the large amounts of potentially malicious traffic, coupled with limited amount of knowledge that can be attributed to the source of the incoming data, as the source is known only by its IP address. Due to the lack of commonly available tooling, many researchers start this analysis from the beginning and so repeat and re-iterate previous research as the bulk of their work. As a result new insight into methods and approaches of analysis is gained at a high cost. Our research approaches this problem by using additional knowledge about the source IP address such as open ports, reverse and forward DNS, BGP routing tables and more, to enhance the researcher's ability to understand the traffic source. The research is a BigData experiment, where large (hundreds of GB) datasets are merged with a two month section of Network Telescope data using a set of Python scripts. The result are written to a Google BigQuery database table. Analysis of the network data is greatly simplified, with questions about the nature of the source, such as its device class (home routing device or server), potential vulnerabilities (open telnet ports or databases) and location becoming relatively easy to answer. Using this approach, researchers can focus on the questions that need answering and efficiently address them. This research could be taken further by using additional data sources such as Geo-location, WHOIS lookups, Threat Intelligence feeds and many others. Other potential areas of research include real-time categorisation of incoming packets, in order to better inform alerting and reporting systems' configuration. In conclusion, categorising Network Telescope data in this way provides insight into the intent of the (apparent) originator and as such is a valuable tool for those seeking to understand the purpose and intent of arriving packets. In particular, the ability to remove packets categorised as non-malicious (e.g. those in the Research category) from the data eliminates a known source of `noise' from the data. This allows the researcher to focus their efforts in a more productive manner.
- Full Text:
- Date Issued: 2019
Geochemical exploration for copper - cobalt in the Democratic Republic of Congo, Central African Copperbelt: a case study on PR851
- Authors: Katombe-Kisumbule, Paul
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3035 , vital:20354
- Description: The PR851 licence area is located at about 80 km west from the town of Likasi in the district of Haut-Katanga and 175 km north-west of Lubumbashi, the capital city of Katanga Province in the Democratic Republic of Congo. The exploration licence was granted by the government of the Democratic Republic of Congo to First Quantum Minerals Ltd through its Congolese subsidiary Compagnie Minière de Sakania Sprl (CoMiSa Sprl) under certificate N˚ CAMI/CR/70/2003 on the 10th of October 2003 for a period of 5 years with a possibility of renewal for 3 years in respect to the new Congolese mining code. The PR851 area lies on fragments of Mines Subgroup rocks of the Roan Group in the Congolese Copperbelt where most of the Cu-Co and stratiform-stratabound deposits such as Kipushi, Ruashi-Etoile, Kinsevere, Kipoi, Luishya, Luswishi, Shituru, Kamoya, Kambove, Tenke- Fungurume, Shinkolobwe, Swambo, Mindingi and Kamoto among others are found. During the 20th century, the Union Minière du Haut Katanga (U.M.H.K.) undertook mineral exploration in the Congolese Copperbelt and numerous copper- and cobalt-occurrences were identified (for instance Kibamba copper occurrence in PR851 area). From 2003, the Compagnie Minière de Sakania Sprl initiated a grassroots exploration program in PR851 area and geochemical exploration survey as one of the mineral exploration tools was implemented to aim at detecting copper and cobalt concentration in soil. The B horizon of the thick tropical soil in the area was sampled and soil samples were sent to Genalysis laboratories in Johannesburg, Republic of South Africa for main chemical analysis of Cu and Co only, whereas 10% of analyzed samples were dispatched to Perth, Western Australia for quality control analysis. Thresholds for anomalies of copper and cobalt were defined by literature comparison, standard deviations and spatial analysis. The anomalies were tested at a later stage by reverse circulation / diamond drilling during the year of 2005 to 2008 and the Cu-Co resources were estimated by Digital Mining Services of Harare, Zimbabwe in the year of 2008. Geological logging of chips from reverse circulation and diamond drill cores revealed that copper mineralization is represented by malachite, chrysocolla, chalcopyrite and bornite whereas cobalt mineralization appeared in form of heterogenite. The source of supergene mineralization remains unknown. Recommendations have been made to undertake more geological exploration work in order to fully investigate the geological setting and structural architecture of the region, which may result in a better understanding of the Cu-Co mineralization system and ore genesis. The latter has been no consensus up-to-date and different theories have been proposed to discuss the ore genesis, including syn- and dia- genetic, synorogenic and sulphide remobilization to late-to-post- orogenic Cu-Zn-Pb Kipushi-type deposit. However, geological observations favored that the diagenetic and syngenetic models are applicable to numerous deposits in the Central African Copperbelt.
- Full Text:
- Date Issued: 2016
- Authors: Katombe-Kisumbule, Paul
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/3035 , vital:20354
- Description: The PR851 licence area is located at about 80 km west from the town of Likasi in the district of Haut-Katanga and 175 km north-west of Lubumbashi, the capital city of Katanga Province in the Democratic Republic of Congo. The exploration licence was granted by the government of the Democratic Republic of Congo to First Quantum Minerals Ltd through its Congolese subsidiary Compagnie Minière de Sakania Sprl (CoMiSa Sprl) under certificate N˚ CAMI/CR/70/2003 on the 10th of October 2003 for a period of 5 years with a possibility of renewal for 3 years in respect to the new Congolese mining code. The PR851 area lies on fragments of Mines Subgroup rocks of the Roan Group in the Congolese Copperbelt where most of the Cu-Co and stratiform-stratabound deposits such as Kipushi, Ruashi-Etoile, Kinsevere, Kipoi, Luishya, Luswishi, Shituru, Kamoya, Kambove, Tenke- Fungurume, Shinkolobwe, Swambo, Mindingi and Kamoto among others are found. During the 20th century, the Union Minière du Haut Katanga (U.M.H.K.) undertook mineral exploration in the Congolese Copperbelt and numerous copper- and cobalt-occurrences were identified (for instance Kibamba copper occurrence in PR851 area). From 2003, the Compagnie Minière de Sakania Sprl initiated a grassroots exploration program in PR851 area and geochemical exploration survey as one of the mineral exploration tools was implemented to aim at detecting copper and cobalt concentration in soil. The B horizon of the thick tropical soil in the area was sampled and soil samples were sent to Genalysis laboratories in Johannesburg, Republic of South Africa for main chemical analysis of Cu and Co only, whereas 10% of analyzed samples were dispatched to Perth, Western Australia for quality control analysis. Thresholds for anomalies of copper and cobalt were defined by literature comparison, standard deviations and spatial analysis. The anomalies were tested at a later stage by reverse circulation / diamond drilling during the year of 2005 to 2008 and the Cu-Co resources were estimated by Digital Mining Services of Harare, Zimbabwe in the year of 2008. Geological logging of chips from reverse circulation and diamond drill cores revealed that copper mineralization is represented by malachite, chrysocolla, chalcopyrite and bornite whereas cobalt mineralization appeared in form of heterogenite. The source of supergene mineralization remains unknown. Recommendations have been made to undertake more geological exploration work in order to fully investigate the geological setting and structural architecture of the region, which may result in a better understanding of the Cu-Co mineralization system and ore genesis. The latter has been no consensus up-to-date and different theories have been proposed to discuss the ore genesis, including syn- and dia- genetic, synorogenic and sulphide remobilization to late-to-post- orogenic Cu-Zn-Pb Kipushi-type deposit. However, geological observations favored that the diagenetic and syngenetic models are applicable to numerous deposits in the Central African Copperbelt.
- Full Text:
- Date Issued: 2016