Biochemical characterisation of Pfj2, a Plasmodium falciparum heat shock protein 40 chaperone potentially involved in protein quality control in the endoplasmic reticulum
- Authors: Afolayan, Omolola Folasade
- Date: 2013
- Subjects: Plasmodium falciparum Endoplasmic reticulum Heat shock proteins Malaria , Mosquito-borne infectious disease
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3883 , http://hdl.handle.net/10962/d1001617
- Description: Plasmodium falciparum is a protozoan parasite that causes a severe form of malaria, a mosquito-borne infectious disease in humans. P. falciparum encodes a number of proteins to facilitate its life-cycle, including a type II heat shock protein 40 (Hsp40), Pfj2. Pfj2 shows a degree of homology to human ERdj5, a resident protein of the endoplasmic reticulum (ER) that promotes protein quality control by facilitating the degradation of misfolded proteins. The overall aim of this study was to further understand the function of Pfj2 in the P. falciparum cell by characterising it biochemically. A bioinformatic analysis of Pfj2 was carried out to enable the identification of a potential ER signal sequence and cleavage site. Furthermore, an analysis of Pfj2 protein sequence was performed to compare domain similarities and identities with typical type II Hsp40s namely, human ERdj5, S. cerevisiae Sis1, human Hsj1a and human DnaJB4. The method used included the insertion of the codon-optimised coding sequence for the processed ER form of Pfj2 into the prokaryotic expression vector, pQE30, to enable overproduction of a histidine-tagged protein. A 62 kDa His₆-Pfj2 was successfully expressed in Escherichia coli and purified using denaturing nickel affinity chromatography. ATPase assays were performed to determine the ability of His₆- Pfj2 to stimulate the chaperone activity of the ER Hsp70, also called immunoglobulin binding protein (BiP). Initial studies were conducted on readily available mammalian His₆-BiP as a control, which was shown to have an intrinsic activity of 12.07±3.92 nmolPi/min/mg. His₆- Pfj2 did not stimulate the ATPase activity of mammalian His₆-BiP, suggesting that it either could not act as a co-chaperone of mammalian His₆-BiP (specificity), or it required a misfolded substrate in the system. Therefore, ongoing studies are addressing the interaction of Pfj2 and misfolded substrates with P. falciparum BiP. The results of these studies will further our understanding of a poorly-studied parasite chaperone that represents a potential drug target for development of novel strategies for the control of a serious human disease
- Full Text:
- Date Issued: 2013
- Authors: Afolayan, Omolola Folasade
- Date: 2013
- Subjects: Plasmodium falciparum Endoplasmic reticulum Heat shock proteins Malaria , Mosquito-borne infectious disease
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3883 , http://hdl.handle.net/10962/d1001617
- Description: Plasmodium falciparum is a protozoan parasite that causes a severe form of malaria, a mosquito-borne infectious disease in humans. P. falciparum encodes a number of proteins to facilitate its life-cycle, including a type II heat shock protein 40 (Hsp40), Pfj2. Pfj2 shows a degree of homology to human ERdj5, a resident protein of the endoplasmic reticulum (ER) that promotes protein quality control by facilitating the degradation of misfolded proteins. The overall aim of this study was to further understand the function of Pfj2 in the P. falciparum cell by characterising it biochemically. A bioinformatic analysis of Pfj2 was carried out to enable the identification of a potential ER signal sequence and cleavage site. Furthermore, an analysis of Pfj2 protein sequence was performed to compare domain similarities and identities with typical type II Hsp40s namely, human ERdj5, S. cerevisiae Sis1, human Hsj1a and human DnaJB4. The method used included the insertion of the codon-optimised coding sequence for the processed ER form of Pfj2 into the prokaryotic expression vector, pQE30, to enable overproduction of a histidine-tagged protein. A 62 kDa His₆-Pfj2 was successfully expressed in Escherichia coli and purified using denaturing nickel affinity chromatography. ATPase assays were performed to determine the ability of His₆- Pfj2 to stimulate the chaperone activity of the ER Hsp70, also called immunoglobulin binding protein (BiP). Initial studies were conducted on readily available mammalian His₆-BiP as a control, which was shown to have an intrinsic activity of 12.07±3.92 nmolPi/min/mg. His₆- Pfj2 did not stimulate the ATPase activity of mammalian His₆-BiP, suggesting that it either could not act as a co-chaperone of mammalian His₆-BiP (specificity), or it required a misfolded substrate in the system. Therefore, ongoing studies are addressing the interaction of Pfj2 and misfolded substrates with P. falciparum BiP. The results of these studies will further our understanding of a poorly-studied parasite chaperone that represents a potential drug target for development of novel strategies for the control of a serious human disease
- Full Text:
- Date Issued: 2013
The study of hydroxyoximes and hydroxamic acids supported on macroporous resins and their use in the rapid seperation of metals
- Authors: Hemmes, Marlene
- Date: 1979
- Subjects: Chromatographic analysis , Separation (Technology) , Metal ions , Solvent extraction , Extraction (Chemistry) , Oximes , Metals -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4453 , http://hdl.handle.net/10962/d1009512
- Description: Introduction: The macroporous Amberlite XAD resins were coated with LIX-64N and examined for the rate of uptake of copper . XAD-7 was by far the best support and gave a satisfactory rate of uptake up to loadings of 60% (w/w). The specific surface area of XAD-7 was measured by the adsorption of methylene blue from aqueous solution. The area of the wetted resin was five times less than that of the dry resin. LIX-65N was purified and the anti isomer characterised using spectroscopic techniques . The rate of uptake of copper was not improved by use of purified LIX-65N or by addition of LIX-63. XAD-7 coated with LIX-65N was used in columns. Elution curves for copper showed negligible tailing, and rapid separations of copper from iron (111), nickel, cobalt and magnesium by selective absorption were achieved. Copper was concentrated from very dilute solution at a flow rate of 50 ml min -1 ,and a 99% recovery was obtained. The method was applied to the rapid determination of copper in brass and bronze. A series of long-chain hydroxamic acids were synthesised and tested for suitability as stationary phase on XAD-7. Oleohydroxamic acid and naphthenohydroxamic acid were the most promising. The r ate of uptake of copper was reduced by the use of nonylphenol or amyl alcohol as a diluent. The capacities for copper of the hydroxamic acids were less when supported on XAD-7 than when used as liquid ionexchangers. The distribution coefficients of cobalt, nickel, zinc, lead, vanadium, uranium, iron (111) and copper were measured as a function of pH. XAD-7 coated with oleohydroxamic acid was used in columns for the rapid separation of iron (111) from copper and of copper from nickel, cobalt, lead and zinc. Copper was concentrated from very dilute solution at a flow rate of 45 ml min -1 and a 100,8% recovery was obtained. Copper was successfully separated from nickel by selective elution. The elution curves obtained show negligible tailing. The resin loaded with oleohydroxamic acid lost capacity due to chemical instability. Naphthenohydroxamic acid supported on XAD-7 was not suitable for use in columns, because it was physically unstable.
- Full Text:
- Date Issued: 1979
- Authors: Hemmes, Marlene
- Date: 1979
- Subjects: Chromatographic analysis , Separation (Technology) , Metal ions , Solvent extraction , Extraction (Chemistry) , Oximes , Metals -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4453 , http://hdl.handle.net/10962/d1009512
- Description: Introduction: The macroporous Amberlite XAD resins were coated with LIX-64N and examined for the rate of uptake of copper . XAD-7 was by far the best support and gave a satisfactory rate of uptake up to loadings of 60% (w/w). The specific surface area of XAD-7 was measured by the adsorption of methylene blue from aqueous solution. The area of the wetted resin was five times less than that of the dry resin. LIX-65N was purified and the anti isomer characterised using spectroscopic techniques . The rate of uptake of copper was not improved by use of purified LIX-65N or by addition of LIX-63. XAD-7 coated with LIX-65N was used in columns. Elution curves for copper showed negligible tailing, and rapid separations of copper from iron (111), nickel, cobalt and magnesium by selective absorption were achieved. Copper was concentrated from very dilute solution at a flow rate of 50 ml min -1 ,and a 99% recovery was obtained. The method was applied to the rapid determination of copper in brass and bronze. A series of long-chain hydroxamic acids were synthesised and tested for suitability as stationary phase on XAD-7. Oleohydroxamic acid and naphthenohydroxamic acid were the most promising. The r ate of uptake of copper was reduced by the use of nonylphenol or amyl alcohol as a diluent. The capacities for copper of the hydroxamic acids were less when supported on XAD-7 than when used as liquid ionexchangers. The distribution coefficients of cobalt, nickel, zinc, lead, vanadium, uranium, iron (111) and copper were measured as a function of pH. XAD-7 coated with oleohydroxamic acid was used in columns for the rapid separation of iron (111) from copper and of copper from nickel, cobalt, lead and zinc. Copper was concentrated from very dilute solution at a flow rate of 45 ml min -1 and a 100,8% recovery was obtained. Copper was successfully separated from nickel by selective elution. The elution curves obtained show negligible tailing. The resin loaded with oleohydroxamic acid lost capacity due to chemical instability. Naphthenohydroxamic acid supported on XAD-7 was not suitable for use in columns, because it was physically unstable.
- Full Text:
- Date Issued: 1979
An investigation into the anxiolytic properties of melatonin in humans
- McCallaghan, Johannes Jacobus
- Authors: McCallaghan, Johannes Jacobus
- Date: 1999
- Subjects: Melatonin , Pineal gland -- Secretions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3772 , http://hdl.handle.net/10962/d1003250 , Melatonin , Pineal gland -- Secretions
- Description: The purpose of this project was to investigate the role of melatonin in the pathophysiology of anxiety in humans. The literature study confirmed the intimate relationship between serotonin and melatonin. Melatonin is not only able to act as an agonist (in physiological concentrations) and an antagonist (at higher concentrations) on serotonin receptors but via control of brain pyridoxal kinase activity might have an effect on GABA, serotonin, dopamine and norepinephrine synthesis. A clinical trial to investigate melatonin's effect on anxiety in humans was conducted as a pilot study. Thirty patients complaining of anxiety participated in a liN of 1" double blind placebo controlled trial. During the experiment each subject was thus exposed to melatonin and a placebo for a week at a time on two occasions. During the first phase of the experiment, (Pair '1) patients showed a statistically significant reduction in their anxiety levels during the first period (P1P1), which was not the case during the second period (P1P2). The improvement however continued during the second phase of the experiment (Pair 2) so that there was also a statistically significant improvement during P 2 P 2 (Period 2 / Pair 2) when placebo was administered. It could not conclusively be shown that melatonin was responsible for the improvement in the patients' anxiety. The explanation for these results suggests thelt the improvement was due to a: 1) placebo effect throughout, 2) psychotherapeutic effect due to contact with a clinician, 3) melatonin induced phase shift in the patient's endogenous melatonin response curve, 4) combination of all 3 options. This pilot study lays the groundwork for a much more exhaustive study in which the melatonin of the patients is determined before melatonin is administered, the role of the clinician is clarified and the most appropriate time for melatonin administration is sought .
- Full Text:
- Date Issued: 1999
- Authors: McCallaghan, Johannes Jacobus
- Date: 1999
- Subjects: Melatonin , Pineal gland -- Secretions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3772 , http://hdl.handle.net/10962/d1003250 , Melatonin , Pineal gland -- Secretions
- Description: The purpose of this project was to investigate the role of melatonin in the pathophysiology of anxiety in humans. The literature study confirmed the intimate relationship between serotonin and melatonin. Melatonin is not only able to act as an agonist (in physiological concentrations) and an antagonist (at higher concentrations) on serotonin receptors but via control of brain pyridoxal kinase activity might have an effect on GABA, serotonin, dopamine and norepinephrine synthesis. A clinical trial to investigate melatonin's effect on anxiety in humans was conducted as a pilot study. Thirty patients complaining of anxiety participated in a liN of 1" double blind placebo controlled trial. During the experiment each subject was thus exposed to melatonin and a placebo for a week at a time on two occasions. During the first phase of the experiment, (Pair '1) patients showed a statistically significant reduction in their anxiety levels during the first period (P1P1), which was not the case during the second period (P1P2). The improvement however continued during the second phase of the experiment (Pair 2) so that there was also a statistically significant improvement during P 2 P 2 (Period 2 / Pair 2) when placebo was administered. It could not conclusively be shown that melatonin was responsible for the improvement in the patients' anxiety. The explanation for these results suggests thelt the improvement was due to a: 1) placebo effect throughout, 2) psychotherapeutic effect due to contact with a clinician, 3) melatonin induced phase shift in the patient's endogenous melatonin response curve, 4) combination of all 3 options. This pilot study lays the groundwork for a much more exhaustive study in which the melatonin of the patients is determined before melatonin is administered, the role of the clinician is clarified and the most appropriate time for melatonin administration is sought .
- Full Text:
- Date Issued: 1999
Polyunsaturated fatty acid metabolism and effects on colon cancer cell biology in vitro.
- Authors: Bulcao, Candice
- Date: 2013
- Subjects: Unsaturated fatty acids , Unsaturated fatty acids in human nutrition , Colon (Anatomy)-- Cancer , Cancer -- Nutritional aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4137 , http://hdl.handle.net/10962/d1016128
- Description: Colon cancer is a leading cause of cancer related deaths worldwide. Lifestyle factors such as diet and exercise have been implicated as important agents in colon cancer development and progression. Epidemiological, in vivo and in vitro studies have found that n-3 polyunsaturated fatty acids (PUFAs) reduce colon carcinoma. The role of n-6 PUFAs remains a controversial topic, with studies indicating both promoting and preventing capabilities published. In order to better understand the effects of PUFAs on colon carcinoma, it is important to have an understanding of how they will be broken down in the body. During this study, in silico metabolism of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) predicted the formation of hydroxy-, di-hydroxy- and epoxy-FAs. A gas chromatography-mass spectrometry method was developed and validated for the detection of these PUFAs and their cytochrome P450 (CYP) metabolites. A human liver microsomal system for the in vitro metabolism of EPA, DHA and AA was optimised in terms of microsomal and PUFA concentration. The system resulted in the metabolism of the positive control, lauric acid, to 12-hydroxy-lauric acid but was unable to metabolise the PUFAs of interest. EPA, DHA and AA reduced cell viability in the colon carcinoma cell lines SW480 and SW620 in the micromolar concentration range (25 – 200 μM). The CYP epoxidation metabolite of EPA, 17, 18-epoxyeicosatetraenoic acid (17, 18-EpETE) resulted in a significant reduction in SW480 cell viability relative to the parent compound at lower concentrations (25 and 50 μM). Annexin V apoptosis analysis revealed that EPA and 17, 18- EpETE did not result in apoptosis in SW480 cells at a concentration of 25 μM and over an incubation period of 24 hours. A significant reduction in reactive oxygen species production was seen in SW480 cells after incubation with 25 μM 17, 18-EpETE for 24 hours. EPA and 17, 18-EpETE were implicated in the reduction of colon cancer metastasis since they were able to reduce SW480 migration and anchorage independent cell growth. These results indicate that the dietary intake of EPA, DHA and AA may be beneficial to one’s health due to the negative effects that these PUFAs had on colon carcinoma. Future studies are needed to confirm these benefits and compare the effects of the PUFAs to their CYP-metabolites.
- Full Text:
- Date Issued: 2013
- Authors: Bulcao, Candice
- Date: 2013
- Subjects: Unsaturated fatty acids , Unsaturated fatty acids in human nutrition , Colon (Anatomy)-- Cancer , Cancer -- Nutritional aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4137 , http://hdl.handle.net/10962/d1016128
- Description: Colon cancer is a leading cause of cancer related deaths worldwide. Lifestyle factors such as diet and exercise have been implicated as important agents in colon cancer development and progression. Epidemiological, in vivo and in vitro studies have found that n-3 polyunsaturated fatty acids (PUFAs) reduce colon carcinoma. The role of n-6 PUFAs remains a controversial topic, with studies indicating both promoting and preventing capabilities published. In order to better understand the effects of PUFAs on colon carcinoma, it is important to have an understanding of how they will be broken down in the body. During this study, in silico metabolism of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) predicted the formation of hydroxy-, di-hydroxy- and epoxy-FAs. A gas chromatography-mass spectrometry method was developed and validated for the detection of these PUFAs and their cytochrome P450 (CYP) metabolites. A human liver microsomal system for the in vitro metabolism of EPA, DHA and AA was optimised in terms of microsomal and PUFA concentration. The system resulted in the metabolism of the positive control, lauric acid, to 12-hydroxy-lauric acid but was unable to metabolise the PUFAs of interest. EPA, DHA and AA reduced cell viability in the colon carcinoma cell lines SW480 and SW620 in the micromolar concentration range (25 – 200 μM). The CYP epoxidation metabolite of EPA, 17, 18-epoxyeicosatetraenoic acid (17, 18-EpETE) resulted in a significant reduction in SW480 cell viability relative to the parent compound at lower concentrations (25 and 50 μM). Annexin V apoptosis analysis revealed that EPA and 17, 18- EpETE did not result in apoptosis in SW480 cells at a concentration of 25 μM and over an incubation period of 24 hours. A significant reduction in reactive oxygen species production was seen in SW480 cells after incubation with 25 μM 17, 18-EpETE for 24 hours. EPA and 17, 18-EpETE were implicated in the reduction of colon cancer metastasis since they were able to reduce SW480 migration and anchorage independent cell growth. These results indicate that the dietary intake of EPA, DHA and AA may be beneficial to one’s health due to the negative effects that these PUFAs had on colon carcinoma. Future studies are needed to confirm these benefits and compare the effects of the PUFAs to their CYP-metabolites.
- Full Text:
- Date Issued: 2013
Early stage ichthyofauna from shallow water habitats of the Angola-Benguela frontal zone
- Authors: Farthing, Matthew William
- Date: 2017
- Subjects: Fishes -- Larvae -- South Africa -- Atlantic coast , Fishes -- Larvae -- Angola -- Atlantic coast , Striped mullet -- Angola -- Atlantic coast
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50442 , vital:25988
- Description: Early stage fishes (larvae and early juveniles) were collected from an array of shallow water (±1.5m) habitats on the warm-temperate southern Angolan coastline between June 2014 and June 2015. This study, the first assessment of the early stages of coastal fishes in Angola, provides important new understanding of non-estuarine shallow water nursery habitat use by coastal fishes from the region. In total, 51 species from 18 teleost families were observed. The exposed surf zone was dominated by postflexion larvae, while the moderately exposed beach and sheltered bay were dominated by early juveniles. Both fish density and diversity peaked in the wet season (Feb – Apr 2015) for all habitats, attributed to the influx of summer spawning species. Diplodus sargus dominated catches from the exposed surf zone, and the timing of observations supports the growing consensus that sparid spawning is dictated by temperature, not season. The similitude of the observed species to those observed in warm temperate South Africa highlights the historical connection of the warm-temperate study area with warm-temperate South Africa, prior to the formation of the Benguela Current as a vicariant barrier. The classification of the study assemblage into established estuarine utilization categories showed that the surf zone hosted more exclusively marine species than comparable surf zones in South Africa, attributed to the absence of estuaries in southern Angola. However, the observation of the marine estuarine dependent Mugil cephalus in this study area devoid of estuaries suggests that estuarine dependency may be regionally specific for some taxa. It appears that the warm, sheltered, nutrient rich waters of Tombua Bay provide typically estuarine associated taxa with a suitable alternative, non-estuarine nursery habitat. This study provides evidence that the importance of estuaries as critical nursery habitats has been overemphasized for some warm-temperate coastal fishes. However, the absence of other marine estuarine dependent species from the study area suggests that some warm-temperate taxa do intrinsically rely on estuarine function for survival.
- Full Text:
- Date Issued: 2017
- Authors: Farthing, Matthew William
- Date: 2017
- Subjects: Fishes -- Larvae -- South Africa -- Atlantic coast , Fishes -- Larvae -- Angola -- Atlantic coast , Striped mullet -- Angola -- Atlantic coast
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/50442 , vital:25988
- Description: Early stage fishes (larvae and early juveniles) were collected from an array of shallow water (±1.5m) habitats on the warm-temperate southern Angolan coastline between June 2014 and June 2015. This study, the first assessment of the early stages of coastal fishes in Angola, provides important new understanding of non-estuarine shallow water nursery habitat use by coastal fishes from the region. In total, 51 species from 18 teleost families were observed. The exposed surf zone was dominated by postflexion larvae, while the moderately exposed beach and sheltered bay were dominated by early juveniles. Both fish density and diversity peaked in the wet season (Feb – Apr 2015) for all habitats, attributed to the influx of summer spawning species. Diplodus sargus dominated catches from the exposed surf zone, and the timing of observations supports the growing consensus that sparid spawning is dictated by temperature, not season. The similitude of the observed species to those observed in warm temperate South Africa highlights the historical connection of the warm-temperate study area with warm-temperate South Africa, prior to the formation of the Benguela Current as a vicariant barrier. The classification of the study assemblage into established estuarine utilization categories showed that the surf zone hosted more exclusively marine species than comparable surf zones in South Africa, attributed to the absence of estuaries in southern Angola. However, the observation of the marine estuarine dependent Mugil cephalus in this study area devoid of estuaries suggests that estuarine dependency may be regionally specific for some taxa. It appears that the warm, sheltered, nutrient rich waters of Tombua Bay provide typically estuarine associated taxa with a suitable alternative, non-estuarine nursery habitat. This study provides evidence that the importance of estuaries as critical nursery habitats has been overemphasized for some warm-temperate coastal fishes. However, the absence of other marine estuarine dependent species from the study area suggests that some warm-temperate taxa do intrinsically rely on estuarine function for survival.
- Full Text:
- Date Issued: 2017
The growth characteristics of sparid otoliths
- Authors: Lang, Judy Brenda
- Date: 1992
- Subjects: Fishes -- Age determination , Otoliths , Sparidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5285 , http://hdl.handle.net/10962/d1005129 , Fishes -- Age determination , Otoliths , Sparidae
- Description: The periodicity of formation of growth increments in the otoliths of South African sparids was validated by the oxytetracycline labelling technique. Intramuscular injections of oxytetracycline at a dosage of 250mg/kg marked the otoliths of laboratory held juvenile sparids, while a dosage range of 50 - 100mg/kg oxytetracycline, injected intramuscularly, marked adult sparids in the field. Laboratory held, larval sparid otoliths were marked by immersion for 24hrs a solution of 100-150mg/l alizarin complexone. Both daily (microstructural) and annual (macrostructural) growth increments were identified in the otoliths. The micro incremental pattern of deposition in the sparid otoliths conformed to the general pattern of otolith structure. Sparid otoliths consisted of a central opaque nucleus composed of multiple primordia. surrounding this nucleus were daily increments which decreased in width as the distance from the nucleus increased. Both check rings and subdaily increments were visible throughout the otolith. Minor environmental changes did not affect micro incremental deposition. Narrow opaque and wide hyaline annual growth zones were identified in sectioned sparid otoliths. Scanning electron microscope analysis of the annual growth zones revealed that microincrements within the opaque zone were narrowly spaced with prominent discontinuous phases. This resulted in the greater optical density and higher protein content of the zone. The hyaline zone was composed of widely spaced daily increments with prominent incremental phases accounting for the translucent nature of this zone. Opaque zone formation in the otoliths of many South African sparids was found to occur primarily during periods of reproductive activity and was shown to be indicative of slow otolith growth. The hyaline zone was formed after the spawning season, representative of fast otolith growth. The results of this study have resolved much of the controversy surrounding the rate of growth and time of formation of the opaque and hyaline growth zones in South African sparid otoliths.
- Full Text:
- Date Issued: 1992
- Authors: Lang, Judy Brenda
- Date: 1992
- Subjects: Fishes -- Age determination , Otoliths , Sparidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5285 , http://hdl.handle.net/10962/d1005129 , Fishes -- Age determination , Otoliths , Sparidae
- Description: The periodicity of formation of growth increments in the otoliths of South African sparids was validated by the oxytetracycline labelling technique. Intramuscular injections of oxytetracycline at a dosage of 250mg/kg marked the otoliths of laboratory held juvenile sparids, while a dosage range of 50 - 100mg/kg oxytetracycline, injected intramuscularly, marked adult sparids in the field. Laboratory held, larval sparid otoliths were marked by immersion for 24hrs a solution of 100-150mg/l alizarin complexone. Both daily (microstructural) and annual (macrostructural) growth increments were identified in the otoliths. The micro incremental pattern of deposition in the sparid otoliths conformed to the general pattern of otolith structure. Sparid otoliths consisted of a central opaque nucleus composed of multiple primordia. surrounding this nucleus were daily increments which decreased in width as the distance from the nucleus increased. Both check rings and subdaily increments were visible throughout the otolith. Minor environmental changes did not affect micro incremental deposition. Narrow opaque and wide hyaline annual growth zones were identified in sectioned sparid otoliths. Scanning electron microscope analysis of the annual growth zones revealed that microincrements within the opaque zone were narrowly spaced with prominent discontinuous phases. This resulted in the greater optical density and higher protein content of the zone. The hyaline zone was composed of widely spaced daily increments with prominent incremental phases accounting for the translucent nature of this zone. Opaque zone formation in the otoliths of many South African sparids was found to occur primarily during periods of reproductive activity and was shown to be indicative of slow otolith growth. The hyaline zone was formed after the spawning season, representative of fast otolith growth. The results of this study have resolved much of the controversy surrounding the rate of growth and time of formation of the opaque and hyaline growth zones in South African sparid otoliths.
- Full Text:
- Date Issued: 1992
The high pressure catalytic hydrogenation of the tannin of black wattle (Acacia mollissima Willd)
- Authors: Silk, M H
- Date: 1947
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21132 , http://hdl.handle.net/10962/6528
- Description: From Introduction: The wattle industry in South Africa has, from its commencement in the middle of the last century, gradually assumed a position of increasing importance in the economic structure of the country. Apart from the provision of a valuable tanning extract for home use and for export, the tree itself has proved of considerable importance to the Union’s mining industries. In addition there would appear to be possibilities for the utilisation in the near future, of the raw ground bark and the wattle extract for the manufacture of a number of by-products, including certain types of plastics.
- Full Text:
- Date Issued: 1947
- Authors: Silk, M H
- Date: 1947
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21132 , http://hdl.handle.net/10962/6528
- Description: From Introduction: The wattle industry in South Africa has, from its commencement in the middle of the last century, gradually assumed a position of increasing importance in the economic structure of the country. Apart from the provision of a valuable tanning extract for home use and for export, the tree itself has proved of considerable importance to the Union’s mining industries. In addition there would appear to be possibilities for the utilisation in the near future, of the raw ground bark and the wattle extract for the manufacture of a number of by-products, including certain types of plastics.
- Full Text:
- Date Issued: 1947
A comparison of web-based technologies to serve images from an Oracle9i database
- Authors: Swales, Dylan
- Date: 2004 , 2013-06-18
- Subjects: Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4583 , http://hdl.handle.net/10962/d1004380 , Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Description: The nature of Internet and Intranet Web applications has changed from a static content-distribution medium into an interactive, dynamic medium, often used to serve multimedia from back-end object-relational databases to Web-enabled clients. Consequently, developers need to make an informed technological choice for developing software that supports a Web-based application for distributing multimedia over networks. This decision is based on several factors. Among the factors are ease of programming, richness of features, scalability, and performance. The research focuses on these key factors when distributing images from an Oracle9i database using Java Servlets, JSP, ASP, and ASP.NET as the server-side development technologies. Prototype applications are developed and tested within each technology: one for single image serving and the other for multiple image serving. A matrix of recommendations is provided to distinguish which technology, or combination of technologies, provides the best performance and development platform for image serving within the studied envirorunent. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
- Authors: Swales, Dylan
- Date: 2004 , 2013-06-18
- Subjects: Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4583 , http://hdl.handle.net/10962/d1004380 , Active server pages , Microsoft .NET , JavaServer pages , Oracle (Computer file) , Internet searching , Web site development--Computer programs , World Wide Web , Online information services
- Description: The nature of Internet and Intranet Web applications has changed from a static content-distribution medium into an interactive, dynamic medium, often used to serve multimedia from back-end object-relational databases to Web-enabled clients. Consequently, developers need to make an informed technological choice for developing software that supports a Web-based application for distributing multimedia over networks. This decision is based on several factors. Among the factors are ease of programming, richness of features, scalability, and performance. The research focuses on these key factors when distributing images from an Oracle9i database using Java Servlets, JSP, ASP, and ASP.NET as the server-side development technologies. Prototype applications are developed and tested within each technology: one for single image serving and the other for multiple image serving. A matrix of recommendations is provided to distinguish which technology, or combination of technologies, provides the best performance and development platform for image serving within the studied envirorunent. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2004
The acute impact of extended aerobic exercise on cognitive performance
- Tichiwanhuyi, Tendayi Stephen
- Authors: Tichiwanhuyi, Tendayi Stephen
- Date: 2015
- Subjects: Aerobic exercises , Cognition -- Effect of exercise on , Exercise -- Physiological aspects , Exercise -- Psychological aspects , Visual perception , Short-term memory , Motor ability , Human information processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5173 , http://hdl.handle.net/10962/d1018182
- Description: Previous research has established a relationship between exercise and cognition, with more emphasis on this ascertained link, being made on the effects of long term and endurance exercise on cognition. However, enhanced worker effectiveness relies on a strong acute collaboration of physical and cognitive performance during task execution. As a result, the purpose of this study was to examine the acute effects of extended aerobic exercise on visual perception, working memory and motor responses, and to achieve this 24 participants (12 males and 12 females) aged between 18 and 24 participated in a 2 bout cycling exercise. The experimental condition had cycling resistance set at 60 percent of each individual’s maximum aerobic output and the control condition had zero cycling resistance, where three cognitive tasks were performed at 10 minute intervals during the cycling exercise. The results showed that exercise did not affect any significant changes on the cognitive performance measures over the entire cycling duration, as well as during the exercise phase (cycling with resistance). However, visual perception improved significantly (p<0.05) immediately after exercise. This led to the conclusion that moderate to high intensity exercise when performed for an extended duration, has selective effects on certain cognitive performance measures, with the time at which the performance is measured during the exercise being a relevant factor to be considered for maximum activation effects of the exercise.
- Full Text:
- Date Issued: 2015
- Authors: Tichiwanhuyi, Tendayi Stephen
- Date: 2015
- Subjects: Aerobic exercises , Cognition -- Effect of exercise on , Exercise -- Physiological aspects , Exercise -- Psychological aspects , Visual perception , Short-term memory , Motor ability , Human information processing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5173 , http://hdl.handle.net/10962/d1018182
- Description: Previous research has established a relationship between exercise and cognition, with more emphasis on this ascertained link, being made on the effects of long term and endurance exercise on cognition. However, enhanced worker effectiveness relies on a strong acute collaboration of physical and cognitive performance during task execution. As a result, the purpose of this study was to examine the acute effects of extended aerobic exercise on visual perception, working memory and motor responses, and to achieve this 24 participants (12 males and 12 females) aged between 18 and 24 participated in a 2 bout cycling exercise. The experimental condition had cycling resistance set at 60 percent of each individual’s maximum aerobic output and the control condition had zero cycling resistance, where three cognitive tasks were performed at 10 minute intervals during the cycling exercise. The results showed that exercise did not affect any significant changes on the cognitive performance measures over the entire cycling duration, as well as during the exercise phase (cycling with resistance). However, visual perception improved significantly (p<0.05) immediately after exercise. This led to the conclusion that moderate to high intensity exercise when performed for an extended duration, has selective effects on certain cognitive performance measures, with the time at which the performance is measured during the exercise being a relevant factor to be considered for maximum activation effects of the exercise.
- Full Text:
- Date Issued: 2015
The development of sustainability criteria to facilitate the selection of sanitation technologies within the Buffalo City Municipality (Eastern Cape Province, South Africa)
- Authors: Hoossein, Shafick
- Date: 2009
- Subjects: Sanitation -- South Africa -- Buffalo City Sustainable development -- South Africa -- Buffalo City Water -- Purification -- South Africa -- Buffalo City Sewage disposal -- South Africa -- Buffalo City Water quality -- South Africa -- Buffalo City Environmental health -- South Africa -- Buffalo City Environmental management -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:32275 , http://hdl.handle.net/10962/d1004595
- Description: Two and a half billion people mostly in sub-Saharan Africa and southern Asia remain without improved sanitation facilities despite the Millennium Development Goal 7's target to halve this number by 2015. While it might be tempting for developing countries such as South Africa to implement the cheapest and most rapidly constructed sanitation services simply to meet the desired target, this could have significant negative implications on human health and the environment over the long-term. As a result, there is a need to ensure that the most appropriate sustainable sanitation technologies are selected during the planning stage. The purpose of this research was therefore to document the development and pilot application of a flexible context-specific decision-support tool for sustainable sanitation technology selection within Buffalo City Municipality (BCM) in the Eastern Cape Province of South Africa. The first step in the development process was to ascertain the current status of sanitation within the municipality, with a specific focus on the main challenges related to the provision, maintenance and performance of these technologies. Thereafter, a participatory approach was employed involving BCM stakeholders to develop a series of sustainability criteria and indicators that took into consideration economic, social, environmental and technical concerns as well as legal requirements. The development process resulted in a list of 38 BCM sustainable sanitation selection criteria that were applied in a pilot study involving rural, urban and peri-urban communities within BCM. Certain criteria related to topographical features and the availability of piped water and land were considered useful for 'coarse screening' while others were applied during 'fine screening'. In order to enhance the context specificity of criteria, each was weighted, through consultation with key BCM stakeholders. This research confirmed that the sanitation situation in BCM was poor and preliminary evidence indicated that sanitation systems were negatively impacting on the quality of water resources within BCM justifying the need for a sustainable sanitation decision support tool. Based on the pilot application of the BCM Sustainability Selection Criteria List, the urine diversion technology was considered the most sustainable technology option in each study site. There were however, certain social criteria that received relatively low sustainability scores and these would need to be addressed prior to the approval of this technology for implementation. The approach adopted in this thesis was considered highly context-specific yet flexible and appropriate for adoption not only by BCM but other municipalities on a range of spatial scales.
- Full Text:
- Date Issued: 2009
- Authors: Hoossein, Shafick
- Date: 2009
- Subjects: Sanitation -- South Africa -- Buffalo City Sustainable development -- South Africa -- Buffalo City Water -- Purification -- South Africa -- Buffalo City Sewage disposal -- South Africa -- Buffalo City Water quality -- South Africa -- Buffalo City Environmental health -- South Africa -- Buffalo City Environmental management -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:32275 , http://hdl.handle.net/10962/d1004595
- Description: Two and a half billion people mostly in sub-Saharan Africa and southern Asia remain without improved sanitation facilities despite the Millennium Development Goal 7's target to halve this number by 2015. While it might be tempting for developing countries such as South Africa to implement the cheapest and most rapidly constructed sanitation services simply to meet the desired target, this could have significant negative implications on human health and the environment over the long-term. As a result, there is a need to ensure that the most appropriate sustainable sanitation technologies are selected during the planning stage. The purpose of this research was therefore to document the development and pilot application of a flexible context-specific decision-support tool for sustainable sanitation technology selection within Buffalo City Municipality (BCM) in the Eastern Cape Province of South Africa. The first step in the development process was to ascertain the current status of sanitation within the municipality, with a specific focus on the main challenges related to the provision, maintenance and performance of these technologies. Thereafter, a participatory approach was employed involving BCM stakeholders to develop a series of sustainability criteria and indicators that took into consideration economic, social, environmental and technical concerns as well as legal requirements. The development process resulted in a list of 38 BCM sustainable sanitation selection criteria that were applied in a pilot study involving rural, urban and peri-urban communities within BCM. Certain criteria related to topographical features and the availability of piped water and land were considered useful for 'coarse screening' while others were applied during 'fine screening'. In order to enhance the context specificity of criteria, each was weighted, through consultation with key BCM stakeholders. This research confirmed that the sanitation situation in BCM was poor and preliminary evidence indicated that sanitation systems were negatively impacting on the quality of water resources within BCM justifying the need for a sustainable sanitation decision support tool. Based on the pilot application of the BCM Sustainability Selection Criteria List, the urine diversion technology was considered the most sustainable technology option in each study site. There were however, certain social criteria that received relatively low sustainability scores and these would need to be addressed prior to the approval of this technology for implementation. The approach adopted in this thesis was considered highly context-specific yet flexible and appropriate for adoption not only by BCM but other municipalities on a range of spatial scales.
- Full Text:
- Date Issued: 2009
Assessing linkages between local ecological knowledge, HIV/AIDS and the commercialisation of natural resources across Southern Africa
- Authors: Weyer, Dylan James
- Date: 2012
- Subjects: AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4769 , http://hdl.handle.net/10962/d1007180 , AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Description: That natural resources (NRs) are important to those experiencing adversity, and, especially, vulnerability associated with HIV/AIDS, is well documented, particularly with respect to food and energy security. What is unclear is where HIV/AIDS ranks in terms of its significance in comparison to other household shocks, the role local ecological knowledge may (LEK) play in households' response to shock, a propos the types of coping strategies that are employed. Consequently, this research aims to bridge the knowledge gap between HIV/AIDS and the degree to which it is contributing to the expansion of NR commercialisation and to explore the unknowns surrounding the influence of LEK on people's choice of coping strategy. A two phase study was designed to provide quantitative rigour with qualitative depth. Phase one was an extensive, rapid survey of NR traders within urban and rural settings in five southern Africa countries. The principle objective was to profile the trade, the livelihoods of those involved and their reasons for entering the trade, to ultimately establish to what degree HIV/AIDS may have been a catalyst for this. Almost one third of the sample entered the trade in response to illness and/or death in their households, with 80% of deaths being of breadwinners. The findings illustrated considerable dependence on the sale of NRs; for almost 60% of the sample it was their household's only source of income. There was evidently increased blurring of the lines between rural and urban NR use with a greater diversity of products being traded in urban areas. Phase two involved in-depth interviews and work with a smaller sample at two sites selected based on the findings from the first phase. It incorporated three groups of households; non-trading, inexperienced trading and experienced trading households. Key areas of focus were household shocks, coping strategies employed in response to these and the role LEK may be playing in the choice of coping strategies. Within a two year period, 95% of households registered at least one shock, of which 80% recorded AIDS-related proxy shocks. Non-trading households were significantly worse-off in this regard, while in the case of non-AIDS proxy shocks, there was no such difference between groups. The most frequently employed coping strategy was the consumption and sale of NRs and was of particular importance when households were faced with AIDS proxy shocks. Trading households emerged as having superior levels of LEK in comparison to non-trading households, even for non-traded NRs, suggesting that prior LEK of NRs opened up opportunities to trade in NR as a coping strategy. Further inspection of the latter group however revealed that the portion of non-trading households who traded on a very ad hoc basis actually had comparable levels of LEK to the trading households. Despite the ad hoc trading households' vulnerable state and their disproportionately high level of AIDS proxy measures, they had at their disposal, sufficient LEK to unlock certain key coping strategies, namely the NR trade. In this sense there are apparent linkages between LEK, HIV/AIDS and the expansion of the commercialisation of NRs.
- Full Text:
- Date Issued: 2012
- Authors: Weyer, Dylan James
- Date: 2012
- Subjects: AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4769 , http://hdl.handle.net/10962/d1007180 , AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Description: That natural resources (NRs) are important to those experiencing adversity, and, especially, vulnerability associated with HIV/AIDS, is well documented, particularly with respect to food and energy security. What is unclear is where HIV/AIDS ranks in terms of its significance in comparison to other household shocks, the role local ecological knowledge may (LEK) play in households' response to shock, a propos the types of coping strategies that are employed. Consequently, this research aims to bridge the knowledge gap between HIV/AIDS and the degree to which it is contributing to the expansion of NR commercialisation and to explore the unknowns surrounding the influence of LEK on people's choice of coping strategy. A two phase study was designed to provide quantitative rigour with qualitative depth. Phase one was an extensive, rapid survey of NR traders within urban and rural settings in five southern Africa countries. The principle objective was to profile the trade, the livelihoods of those involved and their reasons for entering the trade, to ultimately establish to what degree HIV/AIDS may have been a catalyst for this. Almost one third of the sample entered the trade in response to illness and/or death in their households, with 80% of deaths being of breadwinners. The findings illustrated considerable dependence on the sale of NRs; for almost 60% of the sample it was their household's only source of income. There was evidently increased blurring of the lines between rural and urban NR use with a greater diversity of products being traded in urban areas. Phase two involved in-depth interviews and work with a smaller sample at two sites selected based on the findings from the first phase. It incorporated three groups of households; non-trading, inexperienced trading and experienced trading households. Key areas of focus were household shocks, coping strategies employed in response to these and the role LEK may be playing in the choice of coping strategies. Within a two year period, 95% of households registered at least one shock, of which 80% recorded AIDS-related proxy shocks. Non-trading households were significantly worse-off in this regard, while in the case of non-AIDS proxy shocks, there was no such difference between groups. The most frequently employed coping strategy was the consumption and sale of NRs and was of particular importance when households were faced with AIDS proxy shocks. Trading households emerged as having superior levels of LEK in comparison to non-trading households, even for non-traded NRs, suggesting that prior LEK of NRs opened up opportunities to trade in NR as a coping strategy. Further inspection of the latter group however revealed that the portion of non-trading households who traded on a very ad hoc basis actually had comparable levels of LEK to the trading households. Despite the ad hoc trading households' vulnerable state and their disproportionately high level of AIDS proxy measures, they had at their disposal, sufficient LEK to unlock certain key coping strategies, namely the NR trade. In this sense there are apparent linkages between LEK, HIV/AIDS and the expansion of the commercialisation of NRs.
- Full Text:
- Date Issued: 2012
Quantifying crop damage by Grey crowned crane balearica regulorum regulorum and evaluating changes in crane distribution in the North Eastern Cape, South Africa
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
- Full Text:
- Date Issued: 2011
- Authors: Van Niekerk, Mark Harry
- Date: 2011
- Subjects: Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5749 , http://hdl.handle.net/10962/d1005436 , Cranes (Birds) -- South Africa -- Eastern Cape , Cranes (Birds) -- Geographical distribution -- South Africa -- Eastern Cape , Cranes (Birds) -- Behavior -- South Africa -- Eastern Cape , Cranes (Birds) -- Food -- South Africa -- Eastern Cape , Corn -- Effect of grazing on -- South Africa -- Eastern Cape
- Description: Complaints of crop damage by cranes on planted maize in the North Eastern Cape, South Africa, have been increasing since the mid-1990‘s, and in some instances severe losses have been reported. Crop damage by the Grey Crowned Crane Balearica regulorum regulorum near the town of Maclear (31º04´S 28º22´E), has been quantified over two growing seasons, and assessed relative to losses caused by foraging Cape Crows Corvus capensis and other feeding damage assumed to be caused by insects. Twelve fields were selected based on previous patterns of crop depredation. Maize seed in seven of the fields was treated with the chemical ‗Gaucho‘ and five fields were planted with untreated maize. In order to determine the source of losses, twenty quadrats (4 m x 4 m) randomly distributed within each field were visited on average every second day, for a period of up to twenty eight days. Results indicate that seed treatments do act as a deterrent to feeding by both cranes and crows, however crane damage is generally insignificant compared to other sources of damage. My study also reviewed past sightings data of the Grey Crowned Crane in an effort to determine if the conversion of former grassland to plantations in this region may have increased foraging activity in maize fields. The data did not allow for clear-cut conclusions regarding changes in distribution or population trends. Conclusions provide direct input into the management of agricultural areas by enabling landowners to take steps to mitigate crop damage. These mitigation measures may either involve the application of seed treatments, or the planting of low risk crops in high risk areas. Future studies should consider the ppossible detrimental effects of chemical seed treatments on crane biology.
- Full Text:
- Date Issued: 2011
Technology in conservation: towards a system for in-field drone detection of invasive vegetation
- James, Katherine Margaret Frances
- Authors: James, Katherine Margaret Frances
- Date: 2020
- Subjects: Drone aircraft in remote sensing , Neural networks (Computer science) , Drone aircraft in remote sensing -- Case studies , Machine learning , Computer vision , Environmental monitoring -- Remote sensing , Invasive plants -- Monitoring
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/143408 , vital:38244
- Description: Remote sensing can assist in monitoring the spread of invasive vegetation. The adoption of camera-carrying unmanned aerial vehicles, commonly referred to as drones, as remote sensing tools has yielded images of higher spatial resolution than traditional techniques. Drones also have the potential to interact with the environment through the delivery of bio-control or herbicide, as seen with their adoption in precision agriculture. Unlike in agricultural applications, however, invasive plants do not have a predictable position relative to each other within the environment. To facilitate the adoption of drones as an environmental monitoring and management tool, drones need to be able to intelligently distinguish between invasive and non-invasive vegetation on the fly. In this thesis, we present the augmentation of a commercially available drone with a deep machine learning model to investigate the viability of differentiating between an invasive shrub and other vegetation. As a case study, this was applied to the shrub genus Hakea, originating in Australia and invasive in several countries including South Africa. However, for this research, the methodology is important, rather than the chosen target plant. A dataset was collected using the available drone and manually annotated to facilitate the supervised training of the model. Two approaches were explored, namely, classification and semantic segmentation. For each of these, several models were trained and evaluated to find the optimal one. The chosen model was then interfaced with the drone via an Android application on a mobile device and its performance was preliminarily evaluated in the field. Based on these findings, refinements were made and thereafter a thorough field evaluation was performed to determine the best conditions for model operation. Results from the classification task show that deep learning models are capable of distinguishing between target and other shrubs in ideal candidate windows. However, classification in this manner is restricted by the proposal of such candidate windows. End-to-end image segmentation using deep learning overcomes this problem, classifying the image in a pixel-wise manner. Furthermore, the use of appropriate loss functions was found to improve model performance. Field tests show that illumination and shadow pose challenges to the model, but that good recall can be achieved when the conditions are ideal. False positive detection remains an issue that could be improved. This approach shows the potential for drones as an environmental monitoring and management tool when coupled with deep machine learning techniques and outlines potential problems that may be encountered.
- Full Text:
- Date Issued: 2020
- Authors: James, Katherine Margaret Frances
- Date: 2020
- Subjects: Drone aircraft in remote sensing , Neural networks (Computer science) , Drone aircraft in remote sensing -- Case studies , Machine learning , Computer vision , Environmental monitoring -- Remote sensing , Invasive plants -- Monitoring
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/143408 , vital:38244
- Description: Remote sensing can assist in monitoring the spread of invasive vegetation. The adoption of camera-carrying unmanned aerial vehicles, commonly referred to as drones, as remote sensing tools has yielded images of higher spatial resolution than traditional techniques. Drones also have the potential to interact with the environment through the delivery of bio-control or herbicide, as seen with their adoption in precision agriculture. Unlike in agricultural applications, however, invasive plants do not have a predictable position relative to each other within the environment. To facilitate the adoption of drones as an environmental monitoring and management tool, drones need to be able to intelligently distinguish between invasive and non-invasive vegetation on the fly. In this thesis, we present the augmentation of a commercially available drone with a deep machine learning model to investigate the viability of differentiating between an invasive shrub and other vegetation. As a case study, this was applied to the shrub genus Hakea, originating in Australia and invasive in several countries including South Africa. However, for this research, the methodology is important, rather than the chosen target plant. A dataset was collected using the available drone and manually annotated to facilitate the supervised training of the model. Two approaches were explored, namely, classification and semantic segmentation. For each of these, several models were trained and evaluated to find the optimal one. The chosen model was then interfaced with the drone via an Android application on a mobile device and its performance was preliminarily evaluated in the field. Based on these findings, refinements were made and thereafter a thorough field evaluation was performed to determine the best conditions for model operation. Results from the classification task show that deep learning models are capable of distinguishing between target and other shrubs in ideal candidate windows. However, classification in this manner is restricted by the proposal of such candidate windows. End-to-end image segmentation using deep learning overcomes this problem, classifying the image in a pixel-wise manner. Furthermore, the use of appropriate loss functions was found to improve model performance. Field tests show that illumination and shadow pose challenges to the model, but that good recall can be achieved when the conditions are ideal. False positive detection remains an issue that could be improved. This approach shows the potential for drones as an environmental monitoring and management tool when coupled with deep machine learning techniques and outlines potential problems that may be encountered.
- Full Text:
- Date Issued: 2020
Synthesis of silver nanoparticles and their role against a thiazolekinase enzyme from Plasmodium falciparum
- Yao, Jia
- Authors: Yao, Jia
- Date: 2014
- Subjects: Silver , Nanoparticles , Thiazoles , Plasmodium falciparum , Antimalarials , Malaria -- Chemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4168 , http://hdl.handle.net/10962/d1020894
- Description: Malaria, a mosquito-borne infectious disease, caused by the protozoan Plasmodium genus, is the greatest health challenges worldwide. The plasmodial vitamin B1 biosynthetic enzyme PfThzK diverges significantly, both structurally and functionally from its counterpart in higher eukaryotes, thereby making it particularly attractive as a biomedical target. In the present study, PfThzK was recombinantly produced as 6×His fusion protein in E. coli BL21, purified using nickel affinity chromatography and size exclusion chromatography resulting in 1.03% yield and specific activity 0.28 U/mg. The enzyme was found to be a monomer with a molecular mass of 34 kDa. Characterization of the PfThzK showed an optimum temperature and pH of 37°C and 7.5 respectively, and it is relatively stable (t₁/₂=2.66 h). Ag nanoparticles were synthesized by NaBH₄/tannic acid, and characterized by UV-vis spectroscopy and transmission electron microscopy. The morphologies of these Ag nanoparticles (in terms of size) synthesized by tannic acid appeared to be more controlled with the size of 7.06±2.41 nm, compared with those synthesized by NaBH₄, with the sized of 12.9±4.21 nm. The purified PfThzK was challenged with Ag NPs synthesized by tannic acid, and the results suggested that they competitively inhibited PfThzK (89 %) at low concentrations (5-10 μM) with a Ki = 6.45 μM.
- Full Text:
- Date Issued: 2014
- Authors: Yao, Jia
- Date: 2014
- Subjects: Silver , Nanoparticles , Thiazoles , Plasmodium falciparum , Antimalarials , Malaria -- Chemotherapy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4168 , http://hdl.handle.net/10962/d1020894
- Description: Malaria, a mosquito-borne infectious disease, caused by the protozoan Plasmodium genus, is the greatest health challenges worldwide. The plasmodial vitamin B1 biosynthetic enzyme PfThzK diverges significantly, both structurally and functionally from its counterpart in higher eukaryotes, thereby making it particularly attractive as a biomedical target. In the present study, PfThzK was recombinantly produced as 6×His fusion protein in E. coli BL21, purified using nickel affinity chromatography and size exclusion chromatography resulting in 1.03% yield and specific activity 0.28 U/mg. The enzyme was found to be a monomer with a molecular mass of 34 kDa. Characterization of the PfThzK showed an optimum temperature and pH of 37°C and 7.5 respectively, and it is relatively stable (t₁/₂=2.66 h). Ag nanoparticles were synthesized by NaBH₄/tannic acid, and characterized by UV-vis spectroscopy and transmission electron microscopy. The morphologies of these Ag nanoparticles (in terms of size) synthesized by tannic acid appeared to be more controlled with the size of 7.06±2.41 nm, compared with those synthesized by NaBH₄, with the sized of 12.9±4.21 nm. The purified PfThzK was challenged with Ag NPs synthesized by tannic acid, and the results suggested that they competitively inhibited PfThzK (89 %) at low concentrations (5-10 μM) with a Ki = 6.45 μM.
- Full Text:
- Date Issued: 2014
Progestin receptor heterogeneity in a breast cancer cell line
- Authors: Levy, Anita Rochelle
- Date: 1995
- Subjects: Breast -- Cancer , Hormone receptors , Cancer cells -- Growth -- Regulation , Progesterone -- Receptors , Cellular control mechanisms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4039 , http://hdl.handle.net/10962/d1004100 , Breast -- Cancer , Hormone receptors , Cancer cells -- Growth -- Regulation , Progesterone -- Receptors , Cellular control mechanisms
- Description: Anti-oestrogens act via the oestrogen receptor whether they compete with the hormone for binding to the receptor and therefore interfere with DNA binding or inhibit transcriptional activity. These receptors exist as a large 85 complex and/or a small 45 form on sucrose density gradients. High performance ion-exchange chromatography has confirmed that the oestrogen and progestin complex is present in various isoforms. Progestin receptor heterogeneity could be influenced by the presence of oestrogens and anti-oestrogens in the culture media of hormone-dependent neoplastic cells. Cell culture methods offer the opportunity to test effects of specified components in repeated experiments on a homogeneous population of cells. MCF-7 and T47-D human breast cancer cell lines were conditioned to grow in a serum-free environment. There was no difference in cell proliferation rates, nor in their oestrogen or progestin receptor levels when compared to the same cells grown in conventional media. Receptors were present mainly in the large molecular 85 form. Both the MCF-7 and T47-D breast cancer cells showed an increase in proliferation rate with the addition of oestrogen or diethylstilbestrol. There was a corresponding loss of progestin receptor levels and an alteration in the high performance ion-exchange isoforms. Flow cytometry confirmed differences in the S-phase components of the cells following exposure to oestrogens. The proliferation rates of the cell lines as well as their progestin receptor levels decreased when treated with tamoxifen or the hydroxylated tamoxifen. There were marked changes on high performance ion-exchange chromatography profiles. DNA ploidy and S-phase showed signs of toxicity and there was an increase in cellular debris. The MCF-7 and T47-D human breast cancer cell line retained response to antioestrogen saturation.
- Full Text:
- Date Issued: 1995
- Authors: Levy, Anita Rochelle
- Date: 1995
- Subjects: Breast -- Cancer , Hormone receptors , Cancer cells -- Growth -- Regulation , Progesterone -- Receptors , Cellular control mechanisms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4039 , http://hdl.handle.net/10962/d1004100 , Breast -- Cancer , Hormone receptors , Cancer cells -- Growth -- Regulation , Progesterone -- Receptors , Cellular control mechanisms
- Description: Anti-oestrogens act via the oestrogen receptor whether they compete with the hormone for binding to the receptor and therefore interfere with DNA binding or inhibit transcriptional activity. These receptors exist as a large 85 complex and/or a small 45 form on sucrose density gradients. High performance ion-exchange chromatography has confirmed that the oestrogen and progestin complex is present in various isoforms. Progestin receptor heterogeneity could be influenced by the presence of oestrogens and anti-oestrogens in the culture media of hormone-dependent neoplastic cells. Cell culture methods offer the opportunity to test effects of specified components in repeated experiments on a homogeneous population of cells. MCF-7 and T47-D human breast cancer cell lines were conditioned to grow in a serum-free environment. There was no difference in cell proliferation rates, nor in their oestrogen or progestin receptor levels when compared to the same cells grown in conventional media. Receptors were present mainly in the large molecular 85 form. Both the MCF-7 and T47-D breast cancer cells showed an increase in proliferation rate with the addition of oestrogen or diethylstilbestrol. There was a corresponding loss of progestin receptor levels and an alteration in the high performance ion-exchange isoforms. Flow cytometry confirmed differences in the S-phase components of the cells following exposure to oestrogens. The proliferation rates of the cell lines as well as their progestin receptor levels decreased when treated with tamoxifen or the hydroxylated tamoxifen. There were marked changes on high performance ion-exchange chromatography profiles. DNA ploidy and S-phase showed signs of toxicity and there was an increase in cellular debris. The MCF-7 and T47-D human breast cancer cell line retained response to antioestrogen saturation.
- Full Text:
- Date Issued: 1995
The critical natural capital of the Buffalo City Municipality, South Africa : harnessing local action for biodiversity conservation
- Authors: Hagen, Brett
- Date: 2011
- Subjects: Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4753 , http://hdl.handle.net/10962/d1007075 , Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Description: Globally, ecosystems provide services of almost twice the value of global gross national product (Costanza et al., 2006). The Buffalo City Municipality (BCM), South Africa contains biodiversity of national and international importance (Pierce, 2003; Pierce et al., 2005). Despite this, the municipality continues to experience loss of both urban and rural biodiversity (Buffalo City Municipality, 2006a). This study sought to determine the status of biodiversity, and the potential for ecosystem services to contribute to conservation, within the BCM. Biodiversity features, including ecosystem type, species of special concern and biodiversity processes, were identified and mapped using a GIS to produce a biodiversity priority index for the BCM. Current transformation status was then mapped to determine the level of ecosystem degradation within the BCM. Priority biodiversity areas as well as individual biodiversity features were spatially overlain against current transformation status and protected areas and analysed using a GIS to determine the level of degradation and protection of BCM biodiversity. In total 3.5 % of total BCM biodiversity was protected. Of the 24 ecosystem types, 11 (45%) had less than 1% under protection, while 16 (67%) had less than five percent protected. Not restorable areas, thus completely lost to biodiversity conservation, comprised just less than a quarter of the total BCM area while un-impacted areas comprised just 12.3%. Twenty five ecosystem services were identified as being provided by intact natural ecosystems within the BCM. The natural capital providing these services was identified and mapped to produce an ecosystem service index (ESI) using a GIS. This ecosystem service index and the biodiversity priority index were overlain to determine their level of correlation. Overall ESI correlation with priority biodiversity was weak although several individual ecosystem services, including carbon sequestration, showed correlation. Using the above data layers an implementation plan and conservation framework was proposed to assist the coordination of local conservation action within the BCM. It is concluded that ecosystem services are a potentially useful tool for conservationists at the local level seeking to ensure that biodiversity has relevance to and receives protection from broader society.
- Full Text:
- Date Issued: 2011
- Authors: Hagen, Brett
- Date: 2011
- Subjects: Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4753 , http://hdl.handle.net/10962/d1007075 , Natural resources -- South Africa -- Buffalo City , Biodiversity conservation -- South Africa -- Buffalo City , Ecosystem services -- South Africa -- Buffalo City , Nature conservation -- South Africa -- Buffalo City , Environmental protection -- South Africa -- Buffalo City , Environmental degradation -- South Africa -- Buffalo City , Restoration ecology -- South Africa -- Buffalo City
- Description: Globally, ecosystems provide services of almost twice the value of global gross national product (Costanza et al., 2006). The Buffalo City Municipality (BCM), South Africa contains biodiversity of national and international importance (Pierce, 2003; Pierce et al., 2005). Despite this, the municipality continues to experience loss of both urban and rural biodiversity (Buffalo City Municipality, 2006a). This study sought to determine the status of biodiversity, and the potential for ecosystem services to contribute to conservation, within the BCM. Biodiversity features, including ecosystem type, species of special concern and biodiversity processes, were identified and mapped using a GIS to produce a biodiversity priority index for the BCM. Current transformation status was then mapped to determine the level of ecosystem degradation within the BCM. Priority biodiversity areas as well as individual biodiversity features were spatially overlain against current transformation status and protected areas and analysed using a GIS to determine the level of degradation and protection of BCM biodiversity. In total 3.5 % of total BCM biodiversity was protected. Of the 24 ecosystem types, 11 (45%) had less than 1% under protection, while 16 (67%) had less than five percent protected. Not restorable areas, thus completely lost to biodiversity conservation, comprised just less than a quarter of the total BCM area while un-impacted areas comprised just 12.3%. Twenty five ecosystem services were identified as being provided by intact natural ecosystems within the BCM. The natural capital providing these services was identified and mapped to produce an ecosystem service index (ESI) using a GIS. This ecosystem service index and the biodiversity priority index were overlain to determine their level of correlation. Overall ESI correlation with priority biodiversity was weak although several individual ecosystem services, including carbon sequestration, showed correlation. Using the above data layers an implementation plan and conservation framework was proposed to assist the coordination of local conservation action within the BCM. It is concluded that ecosystem services are a potentially useful tool for conservationists at the local level seeking to ensure that biodiversity has relevance to and receives protection from broader society.
- Full Text:
- Date Issued: 2011
NetwIOC: a framework for the automated generation of network-based IOCS for malware information sharing and defence
- Authors: Rudman, Lauren Lynne
- Date: 2018
- Subjects: Malware (Computer software) , Computer networks Security measures , Computer security , Python (Computer program language)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60639 , vital:27809
- Description: With the substantial number of new malware variants found each day, it is useful to have an efficient way to retrieve Indicators of Compromise (IOCs) from the malware in a format suitable for sharing and detection. In the past, these indicators were manually created after inspection of binary samples and network traffic. The Cuckoo Sandbox, is an existing dynamic malware analysis system which meets the requirements for the proposed framework and was extended by adding a few custom modules. This research explored a way to automate the generation of detailed network-based IOCs in a popular format which can be used for sharing. This was done through careful filtering and analysis of the PCAP hie generated by the sandbox, and placing these values into the correct type of STIX objects using Python, Through several evaluations, analysis of what type of network traffic can be expected for the creation of IOCs was conducted, including a brief ease study that examined the effect of analysis time on the number of IOCs created. Using the automatically generated IOCs to create defence and detection mechanisms for the network was evaluated and proved successful, A proof of concept sharing platform developed for the STIX IOCs is showcased at the end of the research.
- Full Text:
- Date Issued: 2018
- Authors: Rudman, Lauren Lynne
- Date: 2018
- Subjects: Malware (Computer software) , Computer networks Security measures , Computer security , Python (Computer program language)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60639 , vital:27809
- Description: With the substantial number of new malware variants found each day, it is useful to have an efficient way to retrieve Indicators of Compromise (IOCs) from the malware in a format suitable for sharing and detection. In the past, these indicators were manually created after inspection of binary samples and network traffic. The Cuckoo Sandbox, is an existing dynamic malware analysis system which meets the requirements for the proposed framework and was extended by adding a few custom modules. This research explored a way to automate the generation of detailed network-based IOCs in a popular format which can be used for sharing. This was done through careful filtering and analysis of the PCAP hie generated by the sandbox, and placing these values into the correct type of STIX objects using Python, Through several evaluations, analysis of what type of network traffic can be expected for the creation of IOCs was conducted, including a brief ease study that examined the effect of analysis time on the number of IOCs created. Using the automatically generated IOCs to create defence and detection mechanisms for the network was evaluated and proved successful, A proof of concept sharing platform developed for the STIX IOCs is showcased at the end of the research.
- Full Text:
- Date Issued: 2018
Overview and comparison of Besshi-type deposits ancient and recent
- Authors: Schoeman, Philo
- Date: 1996
- Subjects: Ore deposits -- Japan , Ore deposits -- Canada , Ore deposits -- Namibia , Ore deposits -- South Africa , Ore deposits
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4983 , http://hdl.handle.net/10962/d1005595 , Ore deposits -- Japan , Ore deposits -- Canada , Ore deposits -- Namibia , Ore deposits -- South Africa , Ore deposits
- Description: Besshi-type deposits range in age from early Proterozoic to early Tertiary, of which the largest number are late Proterozoic, early Palaeozoic or Mesozoic in age. No Archaean examples of Besshi-type deposits are known, probably due to insufficient availability of sialic crust for erosion and clastic marine sedimentation before the start of the Proterozoic. All Besshi-type deposits are contained within sequences of clastic sedimentary rock and intercalated basalts in a marine environment. The basalts and amphibolites are principally tholeiitic in composition. Besshi-type deposits characteristically form stratiform 1enses and sheet-like accumulations of semi-massive to massive sulphide. The main ore assemblage consists dominantly of pyrite and/or pyrrhotite with variable amounts of chalcopyrite, sphalerite and trace galena, arsenopyrite, gold and e1ectrum, barite being absent in general. The median Besshi-type deposit (n=75) contains 1.3 million tonnes (Mt) of massive sulphide with a Cu grade running at 1.43%. It is suggested that Besshi-type deposits form by both exhalative and synsedimentary replacement processes when considering geological features and comparisons with modern analogues in the Guaymas Basin, Middle Valley and Escanaba Trough. The currently forming metalliferous sediments in the Red Sea provide for a brine pool model explaining the lack of footwall feeder zones below sheet-like deposits. Where thick sulphide lenses are contained in some Besshi-type deposits, combinations of exhalative precipitation and sub-sea-floor replacement of permeable sediments and/or volcanic rocks, take place in the upper parts of submarine hydrothermal systems.
- Full Text:
- Date Issued: 1996
- Authors: Schoeman, Philo
- Date: 1996
- Subjects: Ore deposits -- Japan , Ore deposits -- Canada , Ore deposits -- Namibia , Ore deposits -- South Africa , Ore deposits
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4983 , http://hdl.handle.net/10962/d1005595 , Ore deposits -- Japan , Ore deposits -- Canada , Ore deposits -- Namibia , Ore deposits -- South Africa , Ore deposits
- Description: Besshi-type deposits range in age from early Proterozoic to early Tertiary, of which the largest number are late Proterozoic, early Palaeozoic or Mesozoic in age. No Archaean examples of Besshi-type deposits are known, probably due to insufficient availability of sialic crust for erosion and clastic marine sedimentation before the start of the Proterozoic. All Besshi-type deposits are contained within sequences of clastic sedimentary rock and intercalated basalts in a marine environment. The basalts and amphibolites are principally tholeiitic in composition. Besshi-type deposits characteristically form stratiform 1enses and sheet-like accumulations of semi-massive to massive sulphide. The main ore assemblage consists dominantly of pyrite and/or pyrrhotite with variable amounts of chalcopyrite, sphalerite and trace galena, arsenopyrite, gold and e1ectrum, barite being absent in general. The median Besshi-type deposit (n=75) contains 1.3 million tonnes (Mt) of massive sulphide with a Cu grade running at 1.43%. It is suggested that Besshi-type deposits form by both exhalative and synsedimentary replacement processes when considering geological features and comparisons with modern analogues in the Guaymas Basin, Middle Valley and Escanaba Trough. The currently forming metalliferous sediments in the Red Sea provide for a brine pool model explaining the lack of footwall feeder zones below sheet-like deposits. Where thick sulphide lenses are contained in some Besshi-type deposits, combinations of exhalative precipitation and sub-sea-floor replacement of permeable sediments and/or volcanic rocks, take place in the upper parts of submarine hydrothermal systems.
- Full Text:
- Date Issued: 1996
Historical perspectives and future directions for access to land, water and related ecosystem services in the Lower Sundays River Valley, South Africa: implications for human well being
- Authors: Chadzingwa, Karabo
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/442 , vital:19959
- Description: The legacy of South Africa’s history has facilitated unequal access to land and water resources. In the Lower Sundays River Valley (LSRV), a predominantly commercial farming area, differential access to land and water has impacted aspects of ecosystem service access and human well‐being for disenfranchised families over time. Despite the social, political and economic reform efforts in the past two decades, severe inertia towards efforts attempting to increase equitable access to land and water has been experienced. As a result, communities have mobilized and claimed their land from the government through the land restitution process. Based on a mixed‐methods approach, this research explores the ways in which access to land and water over time has influenced current levels of human well‐being among disenfranchised families. Provisioning and cultural ecosystem services were identified as key areas of loss as a result of forced evictions from land. Freedom of choice was a central and cross‐cutting theme regarding the ability to change levels of human well‐being. Although the loss of ecosystem services associated with land and water had an impact on households, the ecosystem services which are regarded as fundamental to human well‐being do not seem to have been lost. The study recommends the wide use of freedom of choice as an indicator for well‐being in the LSRV, as well as a consideration of subjective, objective and psychological measures of well‐being with regards to natural resources and ecosystem services access. Key agents in fostering desirable pathways toward equity and sustainability in the LSRV are identified with stakeholders as private businesses; inclusive governance; empowered and skilled individuals, as well as NGOs.
- Full Text:
- Date Issued: 2016
- Authors: Chadzingwa, Karabo
- Date: 2016
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/442 , vital:19959
- Description: The legacy of South Africa’s history has facilitated unequal access to land and water resources. In the Lower Sundays River Valley (LSRV), a predominantly commercial farming area, differential access to land and water has impacted aspects of ecosystem service access and human well‐being for disenfranchised families over time. Despite the social, political and economic reform efforts in the past two decades, severe inertia towards efforts attempting to increase equitable access to land and water has been experienced. As a result, communities have mobilized and claimed their land from the government through the land restitution process. Based on a mixed‐methods approach, this research explores the ways in which access to land and water over time has influenced current levels of human well‐being among disenfranchised families. Provisioning and cultural ecosystem services were identified as key areas of loss as a result of forced evictions from land. Freedom of choice was a central and cross‐cutting theme regarding the ability to change levels of human well‐being. Although the loss of ecosystem services associated with land and water had an impact on households, the ecosystem services which are regarded as fundamental to human well‐being do not seem to have been lost. The study recommends the wide use of freedom of choice as an indicator for well‐being in the LSRV, as well as a consideration of subjective, objective and psychological measures of well‐being with regards to natural resources and ecosystem services access. Key agents in fostering desirable pathways toward equity and sustainability in the LSRV are identified with stakeholders as private businesses; inclusive governance; empowered and skilled individuals, as well as NGOs.
- Full Text:
- Date Issued: 2016
Distribution of iron-titanium oxides in the vanadiferous main magnetite seam of the upper zone : Northern limb, Bushveld complex
- Authors: Gwatinetsa, Demand
- Date: 2014
- Subjects: Igneous rocks -- South Africa -- Bushveld Complex , Sulfide minerals -- South Africa -- Bushveld Complex , Vanadium -- South Africa -- Bushveld Complex , Titanium dioxide -- South Africa -- Bushveld Complex , Ferric oxide -- South Africa -- Bushveld Complex , Geology -- South Africa -- Bushveld Complex , Mineralogy -- South Africa -- Bushveld Complex , Mines and mineral resources -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5063 , http://hdl.handle.net/10962/d1013281
- Description: The main magnetite seam of the Upper Zone of the Rustenburg Layered Suite (SACS, 1980) on the Bushveld Complex is known to host the world‘s largest vanadium bearing titaniferous iron ores. The vanadiferous titanomagnetites, contain vanadium in sufficient concentrations (1.2 - 2.2 per cent V₂O₅) to be considered as resources and vanadium has been mined historically by a number of companies among them Anglo-American, Highveld Steel and Vanadium and VanMag Resources as well as currently by Evraz Highveld Steel and Vanadium Limited of South Africa. The titanomagnetites contain iron ore in the form of magnetite and titanium with concentrations averaging 50-75 per cent FeO and 12-21 per cent TiO₂. The titaniferous iron ores have been historically dismissed as a source of iron and titanium, due to the known difficulties of using iron ore with high titania content in blast furnaces. The economic potential for the extractability of the titaniferous magnetites lies in the capacity of the ores to be separated into iron rich and titanium rich concentrates usually through, crushing, grinding and magnetic separation. The separatability of iron oxides and titanium oxides, is dependent on the nature in which the titanium oxide occurs, with granular ilmenite being the most favourable since it can be separated from magnetite via magnetic separation. Titanium that occurs as finely exsolved lamellae or as iron-titanium oxides with low titania content such as ulvospinel render the potential recoverability of titanium poor. The Upper Zone vanadiferous titanomagnetites contain titanium in various forms varying from discrete granular ilmenite to finely exsolved lamellae as well as occurring as part of the minerals ulvospinel (Fe₂TiO₄) and titanomagnetite (a solid solution series between ulvospinel and magnetite) . Discrete ilmenite constitutes between 3-5 per cent by volume of the massive titanomagnetite ores, and between 5-10 per cent by volume of the magnetite-plagioclase cumulates with more than 50 per cent opaque oxide minerals. The purpose of this research was to investigate the mineralogical setting and distribution of the iron and titanium oxides within the magnetitite layers from top to bottom as well as spatially along a strike length of 2 000m to determine the potential for the titanium to be extracted from the titanomagnetite ores. The titanomagnetites of the Upper Zone of the Bushveld Complex with particular reference to the Northern Limb where this research was conducted contains titanium oxides as discrete ilmenite grains but in low concentrations whose potential for separate economic extraction will be challenging. The highest concentration of titanium in the magnetite ores is not contained in the granular ilmenite, but rather in ulvospinel and titanomagnetite as illustrated by the marked higher concentration of TiO₂ in the massive ores which contain less granular ilmenite in comparison to the disseminated ores which contain 3 to 8 percentage points higher granular ilmenite than the massive ores. On the scale of the main magnetite seam, the TiO₂ content increases with increasing stratigraphic height from being completely absent in the footwall anorthosite. The V₂2O₅ content also increases with stratigraphic height except for in one of the 3 boreholes where it drops with increasing height. The decrease or increase patterns are repeated in every seam. The titanomagnetites of the main magnetite seam display a variety of textures from coarse granular magnetite and ilmenite, to trellis ilmenite lamellae, intergranular ilmenite and magnesian spinels and fine exsolution lamellae of ulvospinel and ferro-magnesian spinels parallel to the magnetite cleavage. The bottom contact of the main magnetite seam is very sharp and there is no titanium or vanadium in the footwall barely 10cm below the contact. Chromium is present in the bottom of the 4 layers that constitute the main magnetite seam and it upwards decreases rapidly. In boreholes P21 and P55, there are slight reversals in the TiO₂ and V₂O₅ content towards the top of the magnetite seams.
- Full Text:
- Date Issued: 2014
- Authors: Gwatinetsa, Demand
- Date: 2014
- Subjects: Igneous rocks -- South Africa -- Bushveld Complex , Sulfide minerals -- South Africa -- Bushveld Complex , Vanadium -- South Africa -- Bushveld Complex , Titanium dioxide -- South Africa -- Bushveld Complex , Ferric oxide -- South Africa -- Bushveld Complex , Geology -- South Africa -- Bushveld Complex , Mineralogy -- South Africa -- Bushveld Complex , Mines and mineral resources -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5063 , http://hdl.handle.net/10962/d1013281
- Description: The main magnetite seam of the Upper Zone of the Rustenburg Layered Suite (SACS, 1980) on the Bushveld Complex is known to host the world‘s largest vanadium bearing titaniferous iron ores. The vanadiferous titanomagnetites, contain vanadium in sufficient concentrations (1.2 - 2.2 per cent V₂O₅) to be considered as resources and vanadium has been mined historically by a number of companies among them Anglo-American, Highveld Steel and Vanadium and VanMag Resources as well as currently by Evraz Highveld Steel and Vanadium Limited of South Africa. The titanomagnetites contain iron ore in the form of magnetite and titanium with concentrations averaging 50-75 per cent FeO and 12-21 per cent TiO₂. The titaniferous iron ores have been historically dismissed as a source of iron and titanium, due to the known difficulties of using iron ore with high titania content in blast furnaces. The economic potential for the extractability of the titaniferous magnetites lies in the capacity of the ores to be separated into iron rich and titanium rich concentrates usually through, crushing, grinding and magnetic separation. The separatability of iron oxides and titanium oxides, is dependent on the nature in which the titanium oxide occurs, with granular ilmenite being the most favourable since it can be separated from magnetite via magnetic separation. Titanium that occurs as finely exsolved lamellae or as iron-titanium oxides with low titania content such as ulvospinel render the potential recoverability of titanium poor. The Upper Zone vanadiferous titanomagnetites contain titanium in various forms varying from discrete granular ilmenite to finely exsolved lamellae as well as occurring as part of the minerals ulvospinel (Fe₂TiO₄) and titanomagnetite (a solid solution series between ulvospinel and magnetite) . Discrete ilmenite constitutes between 3-5 per cent by volume of the massive titanomagnetite ores, and between 5-10 per cent by volume of the magnetite-plagioclase cumulates with more than 50 per cent opaque oxide minerals. The purpose of this research was to investigate the mineralogical setting and distribution of the iron and titanium oxides within the magnetitite layers from top to bottom as well as spatially along a strike length of 2 000m to determine the potential for the titanium to be extracted from the titanomagnetite ores. The titanomagnetites of the Upper Zone of the Bushveld Complex with particular reference to the Northern Limb where this research was conducted contains titanium oxides as discrete ilmenite grains but in low concentrations whose potential for separate economic extraction will be challenging. The highest concentration of titanium in the magnetite ores is not contained in the granular ilmenite, but rather in ulvospinel and titanomagnetite as illustrated by the marked higher concentration of TiO₂ in the massive ores which contain less granular ilmenite in comparison to the disseminated ores which contain 3 to 8 percentage points higher granular ilmenite than the massive ores. On the scale of the main magnetite seam, the TiO₂ content increases with increasing stratigraphic height from being completely absent in the footwall anorthosite. The V₂2O₅ content also increases with stratigraphic height except for in one of the 3 boreholes where it drops with increasing height. The decrease or increase patterns are repeated in every seam. The titanomagnetites of the main magnetite seam display a variety of textures from coarse granular magnetite and ilmenite, to trellis ilmenite lamellae, intergranular ilmenite and magnesian spinels and fine exsolution lamellae of ulvospinel and ferro-magnesian spinels parallel to the magnetite cleavage. The bottom contact of the main magnetite seam is very sharp and there is no titanium or vanadium in the footwall barely 10cm below the contact. Chromium is present in the bottom of the 4 layers that constitute the main magnetite seam and it upwards decreases rapidly. In boreholes P21 and P55, there are slight reversals in the TiO₂ and V₂O₅ content towards the top of the magnetite seams.
- Full Text:
- Date Issued: 2014