Mineralogy and geochemistry of permian black shales and carbonate concretions in the lower ECCA formations of the Steytlerville- Jansenville area, southern Karoo basin
- Authors: Maake, Laurentias Tebatso
- Date: 2019
- Subjects: Black shales -- South Africa -- Jansenville , Geochemistry Chemistry, Analytic Mineralogy -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40643 , vital:36206
- Description: The Lower Permian Ecca Group formations of the Karoo Basin of South Africa have recently been identified as a target for shale gas exploration. These units, named the Prince Albert, Whitehill and Collingham formations, comprise organic-rich shales with occasional associated carbonate deposits, and siliciclastic facies. Mineralogical and geochemical investigations were conducted into carbonaceous shales and associated sedimentary rocks in the Jansenville area of the southern Karoo Basin with the ultimate aim to decipher the paleoenvironment and post-depositional conditions of these shales and their associated features such as prominent intra-formational carbonate deposits. Sediments of the main Karoo Basin were deposited from ~350 Ma to ~182 Ma, the end of sedimentation being marked by eruption of basaltic lava. This period, which began with the Dwyka continental glaciation, included tectonism of the Cape Fold Belt, the end-Permian mass extinction at ~250 Ma, and major intrusion of dolerite associated with the lavas of the Karoo Large Igneous Province. Subsequent to this, the basin experienced faulting associated with Gondwana breakup, uplift and intrusion of small volume kimberlite and melilite magmas, and erosion resulting in formation of a major escarpment. Each episode was imprinted upon the Karoo rocks and to a greater or lesser extent erases the signature of older episodes. To decipher the depositional paleoenvironment and post-depositional conditions of the black shales and the dolomite concretions posed a challenge due to deformation, orogeny, metamorphism, and weathering and erosion. Therefore, deep borehole core-logging and sampling was generally preferred over surface fieldwork, and trace elements backed up by scanning electron microscopy-based petrography was the method most relied upon to decipher the redox conditions of the black shales and the intra-formational carbonates. Relevant sections from three SOEKOR boreholes SP1/69, AB1/65 and QU1/65 were logged and carbonate concretions localities studied in four field locations. Samples collected from the core and field localities were prepared for thin section optical, SEM petrographical analysis, mineral identification, modal estimation by XRD, major, and trace element analysis by XRF and Laser Ablation-ICPMS, and acid leaching of a sample subset to determine the degree of pyritization (DOP). Logging of the SOEKOR boreholes indicates that in the western part of the basin all three lower Ecca formations, namely the Prince Albert, Whitehill and Collingham, overlie the tillites of the Dwyka Group, whereas near East London only the Whitehill Formation is present. Dwyka diamictites occur in all the studied boreholes overlying the crystalline basement in AB 1/65 and QU 1/65 boreholes whereas in the SP 1/69 the tillites rest above the quartzite of Witteberg Group of the Cape Supergroup. The shale consists of discontinuous, wavy and straight parallel laminae. Parallel, discontinuous and elongate micro-lenses of very fine-grained quartz are diagnostic and suggest late-stage silicification. Thin laminae of black shale are interlaminated with grey clay. The black shales are composed of quartz and clay minerals (illite and chlorite) as the major crystalline minerals with minor quantities of sulphides and heavy minerals. Organic matter occurs as unstructured, anhedral patches of amorphous material. It contains abundant small (~10nm) and less common larger (~100 nm) pores of subsphaeroidal shape. Carbonates occur as cementation and concretions. Heavy minerals identified by SEM include detrital zircon, thorite, titanite, authigenic fluorite, galena, sphene, and sphalerite and apatite, monazite and epidote-group minerals that appear to be of later stage metamorphic origin, some a product of hydrothermal feldspar alteration. Zircon and monazite show evidence of partial corrosion and/or new overgrowth. Titanite occurs in greater abundance in the SP1/69 section than other boreholes, where it exhibits a porphyroblastic texture suggesting secondary growth. These features all suggest modification of detrital minerals by metamorphic fluids and therefore some possible modification of bulk geochemical composition. Pyrite is abundant, commonly occurring as framboidal and occasional euhedral grains. Pyrite-bearing, calcite veins are common in the Whitehill Formation. Some pyrite is metamorphosed to pyrrhotite in the shales adjacent to dolerite intrusions. The carbonate deposits in the lower Ecca occur mostly as large concretions of 0.5-2.5 m in diameter at intensely faulted areas, and as laterally continuous beds at less intensely faulted areas. They consist of dominant dolomite with calcite (differentiated by thin section staining) and minor associated quartz veins, and appear to have formed in an early diagenetic stage of the black shale. Five different dolomite-rock textures were identified indicating varying crystal growth conditions. Calcite cementation types accompany these dolomite textures. The major types include mosaic, sparry and bladed/prismatic calcite cement. Calcite occurs mainly as cement in pores and grain replacement, as well as crudely radial septerian veins. XRD indicates that the carbonate concretions are made up of more than 90% dolomite, especially within the intensely folded areas. The remaining 10% consist of post-depositional quartz veins and secondary calcite associated with the quartz veins. In one locality (VAAL) the carbonate samples are dominates by bladed/prismatic calcite. The black shales in this study have similar geochemical signature to previously analysed samples from the Karoo Basin and to black shales worldwide. The geochemical signature results from the combined input of detrital sedimentary materials as well as enrichment or depletions acquired from pore water, biological activity and during diagenesis. Positive correlation of K2O, Na2O with Al2O3 suggests control by the detrital contribution. CaO and P2O5, have a negative correlation with Al2O3 suggesting a biogenic source. Elemental ratios suggest that the sediments derive from felsic source rock, most likely Cape Supergroup and underlying crystalline basement. These shales exhibit different degrees of trace-element enrichment relative to global average shale, the approximate order being Pb> V> Zn> Cr> Cu> Co > Ni. Assessment of selected trace elements, V/(V+Ni), V/Cr, Ni/Co and EF Mn ratios describes the paleoenvironment of these sediments to have been partially oxygenated before sulphate reduction interface. The pyrite size distribution, DOP, Fe and S correlation points to an organic matter limited environment, where the main sulphur sink is pyrite rather than organic matter. The DOP and Fe/Al indicated that the sediments became anoxic at the sediment-water interface (early diagenetic stages). V/Cr assessment of the dolomite concretions suggested partially oxygenated environment corresponding to the black shale deposition. The occurrence of concretions at the base of the Whitehill Formation, which has the highest TOC content of 14% compared to other associated formations, is evidence that organic matter preservation was important to their origins. The parameters used here to assess the redox conditions of the black shales and the dolomite concretions in this region of the Karoo Basin suggest a normal marine redox environment, rather than the anoxic Black Sea-type environment. The conditions that affected the lower Ecca formations varied from semi-oxygenated to oxygen depletion environment. The oxygen depletion environment occurred during the deposition of the Whitehill Formation of which organic matter preservation was favoured..
- Full Text:
- Date Issued: 2019
- Authors: Maake, Laurentias Tebatso
- Date: 2019
- Subjects: Black shales -- South Africa -- Jansenville , Geochemistry Chemistry, Analytic Mineralogy -- Analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40643 , vital:36206
- Description: The Lower Permian Ecca Group formations of the Karoo Basin of South Africa have recently been identified as a target for shale gas exploration. These units, named the Prince Albert, Whitehill and Collingham formations, comprise organic-rich shales with occasional associated carbonate deposits, and siliciclastic facies. Mineralogical and geochemical investigations were conducted into carbonaceous shales and associated sedimentary rocks in the Jansenville area of the southern Karoo Basin with the ultimate aim to decipher the paleoenvironment and post-depositional conditions of these shales and their associated features such as prominent intra-formational carbonate deposits. Sediments of the main Karoo Basin were deposited from ~350 Ma to ~182 Ma, the end of sedimentation being marked by eruption of basaltic lava. This period, which began with the Dwyka continental glaciation, included tectonism of the Cape Fold Belt, the end-Permian mass extinction at ~250 Ma, and major intrusion of dolerite associated with the lavas of the Karoo Large Igneous Province. Subsequent to this, the basin experienced faulting associated with Gondwana breakup, uplift and intrusion of small volume kimberlite and melilite magmas, and erosion resulting in formation of a major escarpment. Each episode was imprinted upon the Karoo rocks and to a greater or lesser extent erases the signature of older episodes. To decipher the depositional paleoenvironment and post-depositional conditions of the black shales and the dolomite concretions posed a challenge due to deformation, orogeny, metamorphism, and weathering and erosion. Therefore, deep borehole core-logging and sampling was generally preferred over surface fieldwork, and trace elements backed up by scanning electron microscopy-based petrography was the method most relied upon to decipher the redox conditions of the black shales and the intra-formational carbonates. Relevant sections from three SOEKOR boreholes SP1/69, AB1/65 and QU1/65 were logged and carbonate concretions localities studied in four field locations. Samples collected from the core and field localities were prepared for thin section optical, SEM petrographical analysis, mineral identification, modal estimation by XRD, major, and trace element analysis by XRF and Laser Ablation-ICPMS, and acid leaching of a sample subset to determine the degree of pyritization (DOP). Logging of the SOEKOR boreholes indicates that in the western part of the basin all three lower Ecca formations, namely the Prince Albert, Whitehill and Collingham, overlie the tillites of the Dwyka Group, whereas near East London only the Whitehill Formation is present. Dwyka diamictites occur in all the studied boreholes overlying the crystalline basement in AB 1/65 and QU 1/65 boreholes whereas in the SP 1/69 the tillites rest above the quartzite of Witteberg Group of the Cape Supergroup. The shale consists of discontinuous, wavy and straight parallel laminae. Parallel, discontinuous and elongate micro-lenses of very fine-grained quartz are diagnostic and suggest late-stage silicification. Thin laminae of black shale are interlaminated with grey clay. The black shales are composed of quartz and clay minerals (illite and chlorite) as the major crystalline minerals with minor quantities of sulphides and heavy minerals. Organic matter occurs as unstructured, anhedral patches of amorphous material. It contains abundant small (~10nm) and less common larger (~100 nm) pores of subsphaeroidal shape. Carbonates occur as cementation and concretions. Heavy minerals identified by SEM include detrital zircon, thorite, titanite, authigenic fluorite, galena, sphene, and sphalerite and apatite, monazite and epidote-group minerals that appear to be of later stage metamorphic origin, some a product of hydrothermal feldspar alteration. Zircon and monazite show evidence of partial corrosion and/or new overgrowth. Titanite occurs in greater abundance in the SP1/69 section than other boreholes, where it exhibits a porphyroblastic texture suggesting secondary growth. These features all suggest modification of detrital minerals by metamorphic fluids and therefore some possible modification of bulk geochemical composition. Pyrite is abundant, commonly occurring as framboidal and occasional euhedral grains. Pyrite-bearing, calcite veins are common in the Whitehill Formation. Some pyrite is metamorphosed to pyrrhotite in the shales adjacent to dolerite intrusions. The carbonate deposits in the lower Ecca occur mostly as large concretions of 0.5-2.5 m in diameter at intensely faulted areas, and as laterally continuous beds at less intensely faulted areas. They consist of dominant dolomite with calcite (differentiated by thin section staining) and minor associated quartz veins, and appear to have formed in an early diagenetic stage of the black shale. Five different dolomite-rock textures were identified indicating varying crystal growth conditions. Calcite cementation types accompany these dolomite textures. The major types include mosaic, sparry and bladed/prismatic calcite cement. Calcite occurs mainly as cement in pores and grain replacement, as well as crudely radial septerian veins. XRD indicates that the carbonate concretions are made up of more than 90% dolomite, especially within the intensely folded areas. The remaining 10% consist of post-depositional quartz veins and secondary calcite associated with the quartz veins. In one locality (VAAL) the carbonate samples are dominates by bladed/prismatic calcite. The black shales in this study have similar geochemical signature to previously analysed samples from the Karoo Basin and to black shales worldwide. The geochemical signature results from the combined input of detrital sedimentary materials as well as enrichment or depletions acquired from pore water, biological activity and during diagenesis. Positive correlation of K2O, Na2O with Al2O3 suggests control by the detrital contribution. CaO and P2O5, have a negative correlation with Al2O3 suggesting a biogenic source. Elemental ratios suggest that the sediments derive from felsic source rock, most likely Cape Supergroup and underlying crystalline basement. These shales exhibit different degrees of trace-element enrichment relative to global average shale, the approximate order being Pb> V> Zn> Cr> Cu> Co > Ni. Assessment of selected trace elements, V/(V+Ni), V/Cr, Ni/Co and EF Mn ratios describes the paleoenvironment of these sediments to have been partially oxygenated before sulphate reduction interface. The pyrite size distribution, DOP, Fe and S correlation points to an organic matter limited environment, where the main sulphur sink is pyrite rather than organic matter. The DOP and Fe/Al indicated that the sediments became anoxic at the sediment-water interface (early diagenetic stages). V/Cr assessment of the dolomite concretions suggested partially oxygenated environment corresponding to the black shale deposition. The occurrence of concretions at the base of the Whitehill Formation, which has the highest TOC content of 14% compared to other associated formations, is evidence that organic matter preservation was important to their origins. The parameters used here to assess the redox conditions of the black shales and the dolomite concretions in this region of the Karoo Basin suggest a normal marine redox environment, rather than the anoxic Black Sea-type environment. The conditions that affected the lower Ecca formations varied from semi-oxygenated to oxygen depletion environment. The oxygen depletion environment occurred during the deposition of the Whitehill Formation of which organic matter preservation was favoured..
- Full Text:
- Date Issued: 2019
An analysis of the use of DNS for malicious payload distribution
- Authors: Dube, Ishmael
- Date: 2019
- Subjects: Internet domain names , Computer networks -- Security measures , Computer security , Computer network protocols , Data protection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97531 , vital:31447
- Description: The Domain Name System (DNS) protocol is a fundamental part of Internet activities that can be abused by cybercriminals to conduct malicious activities. Previous research has shown that cybercriminals use different methods, including the DNS protocol, to distribute malicious content, remain hidden and avoid detection from various technologies that are put in place to detect anomalies. This allows botnets and certain malware families to establish covert communication channels that can be used to send or receive data and also distribute malicious payloads using the DNS queries and responses. Cybercriminals use the DNS to breach highly protected networks, distribute malicious content, and exfiltrate sensitive information without being detected by security controls put in place by embedding certain strings in DNS packets. This research undertaking broadens this research field and fills in the existing research gap by extending the analysis of DNS being used as a payload distribution channel to detection of domains that are used to distribute different malicious payloads. This research undertaking analysed the use of the DNS in detecting domains and channels that are used for distributing malicious payloads. Passive DNS data which replicate DNS queries on name servers to detect anomalies in DNS queries was evaluated and analysed in order to detect malicious payloads. The research characterises the malicious payload distribution channels by analysing passive DNS traffic and modelling the DNS query and response patterns. The research found that it is possible to detect malicious payload distribution channels through the analysis of DNS TXT resource records.
- Full Text:
- Date Issued: 2019
- Authors: Dube, Ishmael
- Date: 2019
- Subjects: Internet domain names , Computer networks -- Security measures , Computer security , Computer network protocols , Data protection
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97531 , vital:31447
- Description: The Domain Name System (DNS) protocol is a fundamental part of Internet activities that can be abused by cybercriminals to conduct malicious activities. Previous research has shown that cybercriminals use different methods, including the DNS protocol, to distribute malicious content, remain hidden and avoid detection from various technologies that are put in place to detect anomalies. This allows botnets and certain malware families to establish covert communication channels that can be used to send or receive data and also distribute malicious payloads using the DNS queries and responses. Cybercriminals use the DNS to breach highly protected networks, distribute malicious content, and exfiltrate sensitive information without being detected by security controls put in place by embedding certain strings in DNS packets. This research undertaking broadens this research field and fills in the existing research gap by extending the analysis of DNS being used as a payload distribution channel to detection of domains that are used to distribute different malicious payloads. This research undertaking analysed the use of the DNS in detecting domains and channels that are used for distributing malicious payloads. Passive DNS data which replicate DNS queries on name servers to detect anomalies in DNS queries was evaluated and analysed in order to detect malicious payloads. The research characterises the malicious payload distribution channels by analysing passive DNS traffic and modelling the DNS query and response patterns. The research found that it is possible to detect malicious payload distribution channels through the analysis of DNS TXT resource records.
- Full Text:
- Date Issued: 2019
The impact of elephants on thicket vegetation and other mammals in the Eastern Cape Province, South Africa
- Authors: Nuttall-Smith, Gareth David
- Date: 2019
- Subjects: Albany Thicket -- Effect of browsing on , Elephants -- South Africa -- Eastern Cape , African elephant populations -- South Africa -- Eastern Cape , Woody plants -- Effect of browsing on -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Vegetation monitoring -- South Africa -- Eastern Cape , African elephant populations -- Environmental aspects -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , African elephant -- Food , Vegetation dynamics -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76365 , vital:30554
- Description: African elephants (Loxodonta africana) were absent from large portions of the Eastern Cape Province of South Africa for more than 100 years following widespread hunting for ivory. However, recent shifts in land use practices have resulted in the establishment of many private game reserves throughout the region. Some of these reserves have reintroduced elephants, raising management concerns because of the perceived impact that elephants can have on vegetation and the animals that rely on it for resources. My thesis aimed to assess the role of elephants in determining the structure and complexity of the locally important Thicket Biome and how medium and large mammals are affected. I quantified the woody and succulent components of Albany Thicket across nine reserves with elephants between May 2016 and November 2017 using a modified Point-Centre-Quarter method. Camera traps were deployed at each site for the duration of a calendar year to measure the relative abundances of all medium and large mammals at the sites. Across all study sites, climatic conditions (specifically rainfall and temperature) were the primary drivers of woody vegetation structure and diversity. Elephants appeared to have little influence since they were reintroduced at low densities 20 years ago. The associated mammal communities were mostly influenced by the height and basal area coverage of the thicket across the sites. I conclude that because elephant populations have been maintained at relatively low densities across my study sites, negative effects on the thicket vegetation and the associated mammal communities were not observed. In fact, the establishment of private game reserves, even with elephants, present may offer sustainable conservation for the threatened Albany Thicket. However, these elephant populations are still relatively new and changes to the vegetation are likely to be cumulative. Thus, future research should focus on how the vegetation is affected over time. To this end, I recommend the establishment of permanent sampling stations across all reserves with elephants in the Eastern Cape Province.
- Full Text:
- Date Issued: 2019
- Authors: Nuttall-Smith, Gareth David
- Date: 2019
- Subjects: Albany Thicket -- Effect of browsing on , Elephants -- South Africa -- Eastern Cape , African elephant populations -- South Africa -- Eastern Cape , Woody plants -- Effect of browsing on -- South Africa -- Eastern Cape , Animal-plant relationships -- South Africa -- Eastern Cape , Vegetation monitoring -- South Africa -- Eastern Cape , African elephant populations -- Environmental aspects -- South Africa -- Eastern Cape , Biotic communities -- South Africa -- Eastern Cape , African elephant -- Food , Vegetation dynamics -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76365 , vital:30554
- Description: African elephants (Loxodonta africana) were absent from large portions of the Eastern Cape Province of South Africa for more than 100 years following widespread hunting for ivory. However, recent shifts in land use practices have resulted in the establishment of many private game reserves throughout the region. Some of these reserves have reintroduced elephants, raising management concerns because of the perceived impact that elephants can have on vegetation and the animals that rely on it for resources. My thesis aimed to assess the role of elephants in determining the structure and complexity of the locally important Thicket Biome and how medium and large mammals are affected. I quantified the woody and succulent components of Albany Thicket across nine reserves with elephants between May 2016 and November 2017 using a modified Point-Centre-Quarter method. Camera traps were deployed at each site for the duration of a calendar year to measure the relative abundances of all medium and large mammals at the sites. Across all study sites, climatic conditions (specifically rainfall and temperature) were the primary drivers of woody vegetation structure and diversity. Elephants appeared to have little influence since they were reintroduced at low densities 20 years ago. The associated mammal communities were mostly influenced by the height and basal area coverage of the thicket across the sites. I conclude that because elephant populations have been maintained at relatively low densities across my study sites, negative effects on the thicket vegetation and the associated mammal communities were not observed. In fact, the establishment of private game reserves, even with elephants, present may offer sustainable conservation for the threatened Albany Thicket. However, these elephant populations are still relatively new and changes to the vegetation are likely to be cumulative. Thus, future research should focus on how the vegetation is affected over time. To this end, I recommend the establishment of permanent sampling stations across all reserves with elephants in the Eastern Cape Province.
- Full Text:
- Date Issued: 2019
Reproductive isolation mechanisms of two cryptic species of Eccritotarsus (Hemiptera: Miridae), biological control agents of water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae)
- Authors: Mnguni, Sandiso
- Date: 2019
- Subjects: Eccritotarsus , Meridae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68133 , vital:29202
- Description: Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), is one of the world’s worst alien invasive plants. It is indigenous to the Amazon basin in South America but has become a problematic alien invasive in other parts of the world. As such, several host-specific biological control agents have been sourced from the native distributions in South America and have been released to control this plant where it has become problematic. Two of these agents include the geographically and reproductively isolated cryptic species of Eccritotarsus (Hemiptera: Miridae). One of these species was collected in the upper reaches of the Amazon River in Peru, while the other was collected over 3500km away from that site, in Florianopolis, southern Brazil. These cryptic species were thought to be a single species until recently, when DNA barcoding indicated that they were likely to be two species, and the species status has now been confirmed by interbreeding experiments and detailed morphological studies. The Brazilian population remains Eccritotarsus catarinensis (Carvalho), while the Peruvian population is now known as Eccritotarsus eichhorniae (Henry). The aim of this project was to investigate the mating behaviour and other behavioural traits of the two species that have resulted in reproductive isolation, and which could have led to speciation. In addition, investigations involving analysis of chemical compound compositions of the two species aimed to determine the extent to which the compounds played a role in the development and maintenance of reproductive isolation. To achieve the aims, behavioural-observation experiments were conducted in the form of no-choice, bi-choice and multi-choice tests in 1:1, 2:1 and 3:1 sex ratio assessments, both within and between species. Chemical compound compositions of E. catarinensis and E. eichhorniae were also assessed using Nuclear Magnetic Resonance (NMR), Solid-phase micro-extraction (SPME) and Gas-Chromatography Mass-Spectrometry (GC-MS) techniques. In no-choice experiments, the highest number of single and multiple copula incidences, and average total copula duration was found within species while copulation between species was much rarer. In bi-choice experiments, E. eichhorniae females and E. catarinensis males only chose to mate with their respective conspecifics, and within species copulations continued to have higher average total copula duration. In multi-choice experiments, the highest number of single and multiple copula incidences and average total copula duration was also found within species. GC-MS analysis suggested that E. catarinensis females and E. eichhorniae males have unique chemical compounds missing in their conspecifics and same sex of the other species. Further analysis suggested that E. catarinensis females and E. eichhorniae males have similar chemical compound compositions, whereas as E. eichhorniae females and E. catarinensis males have similar chemical compound compositions. These results suggest that there are behavioural differences that led to the development and maintenance of prezygotic reproductive isolation mechanisms, and that this is probably driven by pheromones in chemical compound compositions. These two species were geographically isolated in the native range and the populations have diverged to the point that they are now reproductively incompatible and therefore, distinct species. The main driver of the speciation is most likely mate recognition and attraction, as only reproductively important traits such as pheromones, genitalia, the scent glands and antennae have changed, while other traits, including host range and morphology, have remained remarkably stable. This provides evidence that differences in sexual selection in isolated populations may be important drivers of speciation and reproductive isolation in cryptic species.
- Full Text:
- Date Issued: 2019
- Authors: Mnguni, Sandiso
- Date: 2019
- Subjects: Eccritotarsus , Meridae , Noxious weeds -- Biological control -- South Africa , Aquatic weeds -- Biological control -- South Africa , Water hyacinth -- Biological control -- South Africa , Biological pest control agents
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68133 , vital:29202
- Description: Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach (Pontederiaceae), is one of the world’s worst alien invasive plants. It is indigenous to the Amazon basin in South America but has become a problematic alien invasive in other parts of the world. As such, several host-specific biological control agents have been sourced from the native distributions in South America and have been released to control this plant where it has become problematic. Two of these agents include the geographically and reproductively isolated cryptic species of Eccritotarsus (Hemiptera: Miridae). One of these species was collected in the upper reaches of the Amazon River in Peru, while the other was collected over 3500km away from that site, in Florianopolis, southern Brazil. These cryptic species were thought to be a single species until recently, when DNA barcoding indicated that they were likely to be two species, and the species status has now been confirmed by interbreeding experiments and detailed morphological studies. The Brazilian population remains Eccritotarsus catarinensis (Carvalho), while the Peruvian population is now known as Eccritotarsus eichhorniae (Henry). The aim of this project was to investigate the mating behaviour and other behavioural traits of the two species that have resulted in reproductive isolation, and which could have led to speciation. In addition, investigations involving analysis of chemical compound compositions of the two species aimed to determine the extent to which the compounds played a role in the development and maintenance of reproductive isolation. To achieve the aims, behavioural-observation experiments were conducted in the form of no-choice, bi-choice and multi-choice tests in 1:1, 2:1 and 3:1 sex ratio assessments, both within and between species. Chemical compound compositions of E. catarinensis and E. eichhorniae were also assessed using Nuclear Magnetic Resonance (NMR), Solid-phase micro-extraction (SPME) and Gas-Chromatography Mass-Spectrometry (GC-MS) techniques. In no-choice experiments, the highest number of single and multiple copula incidences, and average total copula duration was found within species while copulation between species was much rarer. In bi-choice experiments, E. eichhorniae females and E. catarinensis males only chose to mate with their respective conspecifics, and within species copulations continued to have higher average total copula duration. In multi-choice experiments, the highest number of single and multiple copula incidences and average total copula duration was also found within species. GC-MS analysis suggested that E. catarinensis females and E. eichhorniae males have unique chemical compounds missing in their conspecifics and same sex of the other species. Further analysis suggested that E. catarinensis females and E. eichhorniae males have similar chemical compound compositions, whereas as E. eichhorniae females and E. catarinensis males have similar chemical compound compositions. These results suggest that there are behavioural differences that led to the development and maintenance of prezygotic reproductive isolation mechanisms, and that this is probably driven by pheromones in chemical compound compositions. These two species were geographically isolated in the native range and the populations have diverged to the point that they are now reproductively incompatible and therefore, distinct species. The main driver of the speciation is most likely mate recognition and attraction, as only reproductively important traits such as pheromones, genitalia, the scent glands and antennae have changed, while other traits, including host range and morphology, have remained remarkably stable. This provides evidence that differences in sexual selection in isolated populations may be important drivers of speciation and reproductive isolation in cryptic species.
- Full Text:
- Date Issued: 2019
Quality in low - cost houses in Nelson Mandela Bay
- Authors: Gogela, Nwabisa
- Date: 2019
- Subjects: Housing development -- South Africa -- Nelson Mandela Bay Municipality , Housing -- South Africa -- Nelson Mandela Bay Municipality Dwellings -- Defects -- South Africa -- Nelson Mandela Bay Municipality Construction industry -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39709 , vital:35350
- Description: Numerous low cost houses in the Nelson Mandela Bay Municipality, and all over South Africa for that matter, have been handed back to the provincial governments by beneficiaries for remedial work in a government programme called Rectification. Several houses have required demolition and be rebuilt because of patent and latent defects. Government spends huge sums of money in rectifying and fixing the defects on houses that should have been built appropriately from the start; this leads to fruitless and ineffective expenditure. The Department of Human Settlements cannot be solely blamed for the poor quality housing delivery. The contractors, project managers and the inspectors from different stakeholders involved in a project also play a massive role in certifying that the houses delivered are of required norms and standards to assist in minimizing poor quality in the delivery of the low cost housing. The funding spent in rectifying low-cost housing has caused huge backlogs, triggering protests within the communities and, regrettably, incomplete projects around the Nelson Mandela Bay Municipality, contributing to urban decay. The aim of this study was to investigate the poor and unacceptable quality in the delivery of low-cost subsidized houses in the Nelson Mandela Metro Region. The focus of the study was to scrutinize the loopholes and the ambiguities that might exist throughout the life cycle of a low cost housing project, and suggestions to mitigate common problems emerging in various projects. A qualitative research approach was followed in this study. The sample was purposively selected and comprised of 15 beneficiaries residing in the three selected NMBM (housing projects), the Ward Councilors (3), Contractors (3), the Quality Assurance Project Managers managing and foreseeing these projects(3), Quality Coordinators(3) and Inspectors from each organization, (NHBRC, ECDHS and HDA), making three (3) in total.. The study revealed that skills shortage, insufficient workforce training and lack of strict quality control are some of the factors affecting quality. Compliancy to norms and standards is not fully emphasized to the relevant stakeholders during the initiation and the commencement of the project. Tools to measure the effectiveness of quality assurance practices are currently used, but it can be argued that they are not effective enough. The study has offered a set of recommendations to address the key findings.
- Full Text:
- Date Issued: 2019
- Authors: Gogela, Nwabisa
- Date: 2019
- Subjects: Housing development -- South Africa -- Nelson Mandela Bay Municipality , Housing -- South Africa -- Nelson Mandela Bay Municipality Dwellings -- Defects -- South Africa -- Nelson Mandela Bay Municipality Construction industry -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39709 , vital:35350
- Description: Numerous low cost houses in the Nelson Mandela Bay Municipality, and all over South Africa for that matter, have been handed back to the provincial governments by beneficiaries for remedial work in a government programme called Rectification. Several houses have required demolition and be rebuilt because of patent and latent defects. Government spends huge sums of money in rectifying and fixing the defects on houses that should have been built appropriately from the start; this leads to fruitless and ineffective expenditure. The Department of Human Settlements cannot be solely blamed for the poor quality housing delivery. The contractors, project managers and the inspectors from different stakeholders involved in a project also play a massive role in certifying that the houses delivered are of required norms and standards to assist in minimizing poor quality in the delivery of the low cost housing. The funding spent in rectifying low-cost housing has caused huge backlogs, triggering protests within the communities and, regrettably, incomplete projects around the Nelson Mandela Bay Municipality, contributing to urban decay. The aim of this study was to investigate the poor and unacceptable quality in the delivery of low-cost subsidized houses in the Nelson Mandela Metro Region. The focus of the study was to scrutinize the loopholes and the ambiguities that might exist throughout the life cycle of a low cost housing project, and suggestions to mitigate common problems emerging in various projects. A qualitative research approach was followed in this study. The sample was purposively selected and comprised of 15 beneficiaries residing in the three selected NMBM (housing projects), the Ward Councilors (3), Contractors (3), the Quality Assurance Project Managers managing and foreseeing these projects(3), Quality Coordinators(3) and Inspectors from each organization, (NHBRC, ECDHS and HDA), making three (3) in total.. The study revealed that skills shortage, insufficient workforce training and lack of strict quality control are some of the factors affecting quality. Compliancy to norms and standards is not fully emphasized to the relevant stakeholders during the initiation and the commencement of the project. Tools to measure the effectiveness of quality assurance practices are currently used, but it can be argued that they are not effective enough. The study has offered a set of recommendations to address the key findings.
- Full Text:
- Date Issued: 2019
The remote sensing of fires and their effects on soil properties in the uKhahlamba Drakensberg Park
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
- Authors: Moore, Natasha Jade
- Date: 2019
- Subjects: Remote sensing -- South Africa -- KwaZulu-Natal , Soil ecology -- South Africa -- KwaZulu-Natal , Grassland fires -- South Africa -- KwaZulu-Natal , Grassland fires -- Remote sensing -- South Africa -- KwaZulu-Natal , Soils -- Effect of fires on -- South Africa -- KwaZulu-Natal , uKhalamba Drakensberg Park (South Africa)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/94400 , vital:31042
- Description: Fires are a common and natural occurrence globally and specifically on the African continent. The Drakensberg Mountains are home to southern Africa’s high-altitude fire-climax grasslands, where fire is the dominant management tool. Fire is used to maintain the grasslands in the uKhahlamba Drakensberg Park (UDP) World Heritage Site, located on the eastern escarpment of the KwaZulu-Natal Drakensberg. This study aimed to investigate the spatial and temporal frequency of fires using remote sensing, and to investigate the effect of fire frequency on soil properties in the UDP. Remote sensing offers a set of supportive tools for the management of this sensitive vegetation and specifically to assess the frequency and spatial extent of fires. Field assessments can then be used to assess the impact of fires. Remotely sensed data were used to determine fire frequency and the spatial extent of fires in the UDP. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detection point data were processed to investigate the temporal resolution of fires. Landsat 5 and 8 imagery were utilised for conducting Normalised Burn Ratios (NBR) to determine the spatial extent of the burn scars of fires. The results from the remotely sensed data were used to select study sites for accessing the effects of fire frequency on soil properties. The remote sensing results showed the main fire season in the UDP was from May to October, and annual burn scars from the available Landsat data for 1998 to 2017 ranged from 22.5% to 57.67% of the UDP. Remote sensing was shown to be an effective tool for monitoring fires in the UDP, with a combination of satellite data producing the best results. Soil properties were highly varied across the UDP. Environmental factors were shown to have a more significant influence on soil properties than fire frequency. This study highlighted the complex nature and diversity of fires and soils across the UDP.
- Full Text:
- Date Issued: 2019
The hypolithic invertebrate community in the eastern Karoo: the role of rock size, microclimate and recolonization
- Authors: Van der Westhuizen, Tara
- Date: 2019
- Subjects: Habitat (Ecology) -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo Invertebrates Ecosystem management -- South Africa -- Karoo Soil microbial ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44191 , vital:37128
- Description: Hypolithic habitats are important for the persistence of fauna that utilize these habitats as refuges and resource patches. Little is known, however, about the composition and structure of this community in the semi-arid Karoo. The current study therefore aims to explore the patterns and processes behind hypolithic communities, through determining the effect of rock size and baboon presence on the hypolithic community, the influence of rock size on the microclimate experienced under rocks, as well as determining the short- (over five days) and long- (over 12 months) term colonisation of the hypolithic habitat following a rock rolling disturbance, in a semi-arid Karoo environment. The hypolithic fauna encountered, and the temperature and moisture content experienced under a range of rock sizes were measured. Additionally, hypolithic fauna under rocks that were rolled to mimic rock rolling by baboons were sampled after a set period (i.e. over five days and 12 months). Large rocks were found to provide a more stable microclimate than small rocks. The probability of hypolithic fauna presence was influenced by rock size and season, and hypolithic fauna abundance (except in the dry season), richness, body size and biomass did not correlate with rock size. Additionally, the probability of detecting hypolithic fauna under intermediate sized and larger rocks was greater in the presence of baboons than in the absence of baboons, and in the presence of baboons hypolithic fauna richness increased with rock size. Furthermore, it was shown that hypolithic fauna abundance and biomass did not differ under rolled rocks over a short- (i.e. over five days) or long- (i.e. over 12 months) term period. The short-term colonisation of hypolithic habitats was not influenced by season or rock density. Lastly, most of the change in hypolithic community composition (over 12 months) occurred in the first three months and thereafter the hypolithic community composition approached pre-disturbance levels in month 12. The hypolithic habitat was shown to be influenced by a variety of conditions and processes affecting hypolithic community composition and structure. This study therefore contributes to our understanding of the hypolithic invertebrate community in the eastern Karoo, and the influence of rock size, baboon presence, microclimate and colonisation on hypolithic community composition and structure.
- Full Text:
- Date Issued: 2019
- Authors: Van der Westhuizen, Tara
- Date: 2019
- Subjects: Habitat (Ecology) -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo Invertebrates Ecosystem management -- South Africa -- Karoo Soil microbial ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44191 , vital:37128
- Description: Hypolithic habitats are important for the persistence of fauna that utilize these habitats as refuges and resource patches. Little is known, however, about the composition and structure of this community in the semi-arid Karoo. The current study therefore aims to explore the patterns and processes behind hypolithic communities, through determining the effect of rock size and baboon presence on the hypolithic community, the influence of rock size on the microclimate experienced under rocks, as well as determining the short- (over five days) and long- (over 12 months) term colonisation of the hypolithic habitat following a rock rolling disturbance, in a semi-arid Karoo environment. The hypolithic fauna encountered, and the temperature and moisture content experienced under a range of rock sizes were measured. Additionally, hypolithic fauna under rocks that were rolled to mimic rock rolling by baboons were sampled after a set period (i.e. over five days and 12 months). Large rocks were found to provide a more stable microclimate than small rocks. The probability of hypolithic fauna presence was influenced by rock size and season, and hypolithic fauna abundance (except in the dry season), richness, body size and biomass did not correlate with rock size. Additionally, the probability of detecting hypolithic fauna under intermediate sized and larger rocks was greater in the presence of baboons than in the absence of baboons, and in the presence of baboons hypolithic fauna richness increased with rock size. Furthermore, it was shown that hypolithic fauna abundance and biomass did not differ under rolled rocks over a short- (i.e. over five days) or long- (i.e. over 12 months) term period. The short-term colonisation of hypolithic habitats was not influenced by season or rock density. Lastly, most of the change in hypolithic community composition (over 12 months) occurred in the first three months and thereafter the hypolithic community composition approached pre-disturbance levels in month 12. The hypolithic habitat was shown to be influenced by a variety of conditions and processes affecting hypolithic community composition and structure. This study therefore contributes to our understanding of the hypolithic invertebrate community in the eastern Karoo, and the influence of rock size, baboon presence, microclimate and colonisation on hypolithic community composition and structure.
- Full Text:
- Date Issued: 2019
A Statistical assessment of available solar resource across multiple sites in South Africa
- Authors: Eastwood, Kirstie
- Date: 2019
- Subjects: Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39907 , vital:35505
- Description: Around the globe, fossil fuels remain the primary source of energy at around 78% of the world’s total energy consumption. However, the associated carbon emissions, environmental impact, the depletion of fossil fuels and price and cost volatility are factors influencing the growing popularity of research into renewable energy. Solar power is acknowledged as the fastest-growing renewable energy, but the uncertainty surrounding the long-term projections of solar irradiance available for energy conversion is a hindrance when discussing the financial risk with potential investors. This study investigates the quality of freely available solar resource data in South Africa as well as proposes techniques for potential solar farm site comparisons. Tolerance intervals derived within a Bayesian framework provide information on the future available solar resource across multiple sites. These techniques capture the inherent variability in the available solar resource which equips investors with statistical methods that lead to the better understanding of the solar resource and thus aids in better decision-making.
- Full Text:
- Date Issued: 2019
- Authors: Eastwood, Kirstie
- Date: 2019
- Subjects: Mathematical statistics
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39907 , vital:35505
- Description: Around the globe, fossil fuels remain the primary source of energy at around 78% of the world’s total energy consumption. However, the associated carbon emissions, environmental impact, the depletion of fossil fuels and price and cost volatility are factors influencing the growing popularity of research into renewable energy. Solar power is acknowledged as the fastest-growing renewable energy, but the uncertainty surrounding the long-term projections of solar irradiance available for energy conversion is a hindrance when discussing the financial risk with potential investors. This study investigates the quality of freely available solar resource data in South Africa as well as proposes techniques for potential solar farm site comparisons. Tolerance intervals derived within a Bayesian framework provide information on the future available solar resource across multiple sites. These techniques capture the inherent variability in the available solar resource which equips investors with statistical methods that lead to the better understanding of the solar resource and thus aids in better decision-making.
- Full Text:
- Date Issued: 2019
The influence of briefing on Eastern Cape government project outcomes
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Government projects -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44562 , vital:38128
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
- Authors: Binqela, Lukhanyo
- Date: 2019
- Subjects: Government projects -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/44562 , vital:38128
- Description: South African Government projects are frequently completed with large cost overruns, extended schedules, quality concerns and an increase in emerging contractors making a significant loss in projects they undertake. The construction phase has been the focus of many studies on the causes of unfavourable project outcomes. However, the crucial stages in the construction process that influence the success of a project are the early ones. This is where major decisions that influence the features and form of a project occur. This study, which adopts a case study approach, aims to establish the influence of the brief development process on the outcome of Government projects in the Eastern Cape. Through the reviewed literature and primary data collection, the study aimed at establishing the influence of the brief that is utilised for a need analysis, to define a detailed scope of works, stakeholder engagement and the time management on Eastern Cape Government project outcomes. The Sarah Baartman district was the selected geographical scope of research. Five projects were selected; these included three schools, one emergency medical service facility and one office facility. The study revealed that Eastern Cape Government projects brief development is based on the client department 2013 Published Norms and Standards for state buildings and a need analysis for other stakeholders is not considered. The study further revealed that there is no stakeholder management in government projects; therefore, there is no stakeholder engagement plan during the brief development. The study further revealed that government time management is suboptimal because stakeholder needs are not realised. The research also found that Eastern Cape Government projects do not achieve stakeholder satisfaction and are delivered late. However, some Government projects are able to meet the desired quality and are within budget. The study thus proposes that the Eastern Cape Government projects need to adopt the dynamic brief development process and implement stakeholder management. The brief development process should be an ongoing process extending throughout the project life cycle responding in an innovative manner to emerging stakeholder requirements.
- Full Text:
- Date Issued: 2019
Categorising Network Telescope data using big data enrichment techniques
- Authors: Davis, Michael Reginald
- Date: 2019
- Subjects: Denial of service attacks , Big data , Computer networks -- Security measures
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92941 , vital:30766
- Description: Network Telescopes, Internet backbone sampling, IDS and other forms of network-sourced Threat Intelligence provide researchers with insight into the methods and intent of remote entities by capturing network traffic and analysing the resulting data. This analysis and determination of intent is made difficult by the large amounts of potentially malicious traffic, coupled with limited amount of knowledge that can be attributed to the source of the incoming data, as the source is known only by its IP address. Due to the lack of commonly available tooling, many researchers start this analysis from the beginning and so repeat and re-iterate previous research as the bulk of their work. As a result new insight into methods and approaches of analysis is gained at a high cost. Our research approaches this problem by using additional knowledge about the source IP address such as open ports, reverse and forward DNS, BGP routing tables and more, to enhance the researcher's ability to understand the traffic source. The research is a BigData experiment, where large (hundreds of GB) datasets are merged with a two month section of Network Telescope data using a set of Python scripts. The result are written to a Google BigQuery database table. Analysis of the network data is greatly simplified, with questions about the nature of the source, such as its device class (home routing device or server), potential vulnerabilities (open telnet ports or databases) and location becoming relatively easy to answer. Using this approach, researchers can focus on the questions that need answering and efficiently address them. This research could be taken further by using additional data sources such as Geo-location, WHOIS lookups, Threat Intelligence feeds and many others. Other potential areas of research include real-time categorisation of incoming packets, in order to better inform alerting and reporting systems' configuration. In conclusion, categorising Network Telescope data in this way provides insight into the intent of the (apparent) originator and as such is a valuable tool for those seeking to understand the purpose and intent of arriving packets. In particular, the ability to remove packets categorised as non-malicious (e.g. those in the Research category) from the data eliminates a known source of `noise' from the data. This allows the researcher to focus their efforts in a more productive manner.
- Full Text:
- Date Issued: 2019
- Authors: Davis, Michael Reginald
- Date: 2019
- Subjects: Denial of service attacks , Big data , Computer networks -- Security measures
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/92941 , vital:30766
- Description: Network Telescopes, Internet backbone sampling, IDS and other forms of network-sourced Threat Intelligence provide researchers with insight into the methods and intent of remote entities by capturing network traffic and analysing the resulting data. This analysis and determination of intent is made difficult by the large amounts of potentially malicious traffic, coupled with limited amount of knowledge that can be attributed to the source of the incoming data, as the source is known only by its IP address. Due to the lack of commonly available tooling, many researchers start this analysis from the beginning and so repeat and re-iterate previous research as the bulk of their work. As a result new insight into methods and approaches of analysis is gained at a high cost. Our research approaches this problem by using additional knowledge about the source IP address such as open ports, reverse and forward DNS, BGP routing tables and more, to enhance the researcher's ability to understand the traffic source. The research is a BigData experiment, where large (hundreds of GB) datasets are merged with a two month section of Network Telescope data using a set of Python scripts. The result are written to a Google BigQuery database table. Analysis of the network data is greatly simplified, with questions about the nature of the source, such as its device class (home routing device or server), potential vulnerabilities (open telnet ports or databases) and location becoming relatively easy to answer. Using this approach, researchers can focus on the questions that need answering and efficiently address them. This research could be taken further by using additional data sources such as Geo-location, WHOIS lookups, Threat Intelligence feeds and many others. Other potential areas of research include real-time categorisation of incoming packets, in order to better inform alerting and reporting systems' configuration. In conclusion, categorising Network Telescope data in this way provides insight into the intent of the (apparent) originator and as such is a valuable tool for those seeking to understand the purpose and intent of arriving packets. In particular, the ability to remove packets categorised as non-malicious (e.g. those in the Research category) from the data eliminates a known source of `noise' from the data. This allows the researcher to focus their efforts in a more productive manner.
- Full Text:
- Date Issued: 2019
Targeting allosteric sites of Escherichia coli heat shock protein 70 for antibiotic development
- Authors: Okeke, Chiamaka Jessica
- Date: 2019
- Subjects: Heat shock proteins , Escherichia coli , Allosteric proteins , Antibiotics , Molecular chaperones , Ligands (Biochemistry) , Molecular dynamics , Principal components analysis , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115998 , vital:34287
- Description: Hsp70s are members of the heat shock proteins family with a molecular weight of 70-kDa and are the most abundant group in bacterial and eukaryotic systems, hence the most extensively studied ones. These proteins are molecular chaperones that play a significant role in protein homeostasis by facilitating appropriate folding of proteins, preventing proteins from aggregating and misfolding. They are also involved in translocation of proteins into subcellular compartments and protection of cells against stress. Stress caused by environmental or biological factors affects the functionality of the cell. In response to these stressful conditions, up-regulation of Hsp70s ensures that the cells are protected by balancing out unfolded proteins giving them ample time to repair denatured proteins. Hsp70s is connected to numerous illnesses such as autoimmune and neurodegenerative diseases, bacterial infection, cancer, malaria, and obesity. The multi-functional nature of Hsp70s predisposes them as promising therapeutic targets. Hsp70s play vital roles in various cell developments, and survival pathways, therefore targeting this protein will provide a new avenue towards the discovery of active therapeutic agents for the treatment of a wide range of diseases. Allosteric sites of these proteins in its multi-conformational states have not been explored for inhibitory properties hence the aim of this study. This study aims at identifying allosteric sites that inhibit the ATPase and substrate binding activities using computational approaches. Using E. coli as a model organism, molecular docking for high throughput virtual screening was carried out using 623 compounds from the South African Natural Compounds Database (SANCDB; https://sancdb.rubi.ru.ac.za/) against identified allosteric sites. Ligands with the highest binding affinity (good binders) interacting with critical allosteric residues that are druggable were identified. Molecular dynamics (MD) simulation was also performed on the identified hits to assess for protein-inhibitor complex stability. Finally, principal component analysis (PCA) was performed to understand the structural dynamics of the ligand-free and ligand-bound structures during MD simulation.
- Full Text:
- Date Issued: 2019
- Authors: Okeke, Chiamaka Jessica
- Date: 2019
- Subjects: Heat shock proteins , Escherichia coli , Allosteric proteins , Antibiotics , Molecular chaperones , Ligands (Biochemistry) , Molecular dynamics , Principal components analysis , South African Natural Compounds Database
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/115998 , vital:34287
- Description: Hsp70s are members of the heat shock proteins family with a molecular weight of 70-kDa and are the most abundant group in bacterial and eukaryotic systems, hence the most extensively studied ones. These proteins are molecular chaperones that play a significant role in protein homeostasis by facilitating appropriate folding of proteins, preventing proteins from aggregating and misfolding. They are also involved in translocation of proteins into subcellular compartments and protection of cells against stress. Stress caused by environmental or biological factors affects the functionality of the cell. In response to these stressful conditions, up-regulation of Hsp70s ensures that the cells are protected by balancing out unfolded proteins giving them ample time to repair denatured proteins. Hsp70s is connected to numerous illnesses such as autoimmune and neurodegenerative diseases, bacterial infection, cancer, malaria, and obesity. The multi-functional nature of Hsp70s predisposes them as promising therapeutic targets. Hsp70s play vital roles in various cell developments, and survival pathways, therefore targeting this protein will provide a new avenue towards the discovery of active therapeutic agents for the treatment of a wide range of diseases. Allosteric sites of these proteins in its multi-conformational states have not been explored for inhibitory properties hence the aim of this study. This study aims at identifying allosteric sites that inhibit the ATPase and substrate binding activities using computational approaches. Using E. coli as a model organism, molecular docking for high throughput virtual screening was carried out using 623 compounds from the South African Natural Compounds Database (SANCDB; https://sancdb.rubi.ru.ac.za/) against identified allosteric sites. Ligands with the highest binding affinity (good binders) interacting with critical allosteric residues that are druggable were identified. Molecular dynamics (MD) simulation was also performed on the identified hits to assess for protein-inhibitor complex stability. Finally, principal component analysis (PCA) was performed to understand the structural dynamics of the ligand-free and ligand-bound structures during MD simulation.
- Full Text:
- Date Issued: 2019
Recruitment of bivalve molluscs with specific emphasis on Mytilus galloprovincialis in the Knysna estuarine embayment, South Africa
- Authors: Radloff, James Victor
- Date: 2019
- Subjects: Mytilus galloprovincialis -- South Africa -- Knysna Lagoon , Introduced aquatic organisms -- South Africa -- Knysna Lagoon , Mexilhao mussel -- South Africa -- Knysna Lagoon , Oysters -- South Africa -- Knysna Lagoon , Mytilidae -- South Africa -- Knysna Lagoon , Bivalves -- South Africa -- Knysna Lagoon
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76733 , vital:30613
- Description: Alien invasive species have the ability to transform or alter environments, often causing severe ecological and/or economic impacts. Marine bioinvasions are occurring globally and are most often facilitated (intentially and accidently) through anthropogenic activities including the building of inter-oceanic canals, shipping and commerce. The Mediterranean mussel, Mytilus galloprovincialis, is a globally successful marine alien invasive species which was first recorded on the west coast of South Africa in the late 1970s and the south coast in 1988. This species is thought to have reached the Knysna Estuary in the early 2000s and has colonised all man-made hard substrata in the embayment of the estuary. Although there are studies on recruitment of M. galloprovincialis on the rocky intertidal coasts of South Africa, there is little information on recruitment of this species in more sheltered estuarine environments. This study aimed to determine recruitment levels of M. galloprovincialis and other bivalves within the Knysna estuarine embayment. To determine monthly recruitment, 10 recruit collectors/pads (plastic pot scourers) were placed at three separate locations within the embayment of the estuary for a week on a monthly basis for 20 months. In addition, recruitment of M. galloprovincialis over spring and neap tides and different lunar phases was also determined at two sites within the Knysna estuarine embayment during the main reproductive season in 2018. The pads were deployed three days before a neap/spring tide and then collected three days after the respective tide. Finally, to look at how rapidly M. galloprovincialis and other macroinvertebrates (when M. galloprovincialis was excluded) would re-colonise free space, 18 plots (15x15 cm), consisting of three treatments including a control (A,B and C), were cleared in M. galloprovincialis mussel beds and then photographed monthly for 12 months. Four bivalve taxa (Mytilus galloprovincialis, Perna perna, Ostreidae, unidentified mytilid) were recorded during the monthly study. Recruitment levels for all bivalves differed significantly (P < 0.001) between months and sites, with peak recruitment occurring from late spring to early autumn (November – March). Mytilus galloprovincialis recruitment levels were greater than other bivalves and were up to 4.5x greater than other taxa. Recruitment also varied between years possibly owing to differences in larval supply and/or environmental factors. Spatial variation in bivalve recruitment was observed throughout the study. The greatest recruitment was at the site (Thesen Island Wharf) closer to the entrance of the embayment. By contrast at the site (Railway Bridge) furthest from the entrance lower recruitment was found. This difference is possibly due to differences in hydrodynamics or other biological and/or environmental factors. A preliminary tidal study found that M. galloprovincialis had significantly higher (P < 0.001) recruitment levels over spring tides than neap tides at Thesen Island Wharf, whereas recruitment at the Railway Bridge on spring and neap tides was not significantly different. In the study undertaken in the reproductive season only, recruitment levels were high over a two week period during both a spring and neap tide, suggesting that factors other than lunar phase and the state of tide are more important in determining the timing and intensity of recruitment. The clearance plots created and photographed over a 12 month period showed that M. galloprovincialis rapidly occupied free space (eight months to virtually cover all free space) by encroachment from the adjacent mussel bed. Limpets and barnacles were only able to colonise cleared space when M. galloprovincialis was excluded, suggesting that the mussel has the ability to outcompete indigenous macrofauna for space. The high recruitment levels of M. galloprovincialis compared to other indigenous bivalves, as well as its ability to occupy space rapidly are traits that must contribute to the success of the invasion of this species within the Knysna estuarine embayment, particulary within Thesen Islands Marina and Thesen Island Wharf.
- Full Text:
- Date Issued: 2019
- Authors: Radloff, James Victor
- Date: 2019
- Subjects: Mytilus galloprovincialis -- South Africa -- Knysna Lagoon , Introduced aquatic organisms -- South Africa -- Knysna Lagoon , Mexilhao mussel -- South Africa -- Knysna Lagoon , Oysters -- South Africa -- Knysna Lagoon , Mytilidae -- South Africa -- Knysna Lagoon , Bivalves -- South Africa -- Knysna Lagoon
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/76733 , vital:30613
- Description: Alien invasive species have the ability to transform or alter environments, often causing severe ecological and/or economic impacts. Marine bioinvasions are occurring globally and are most often facilitated (intentially and accidently) through anthropogenic activities including the building of inter-oceanic canals, shipping and commerce. The Mediterranean mussel, Mytilus galloprovincialis, is a globally successful marine alien invasive species which was first recorded on the west coast of South Africa in the late 1970s and the south coast in 1988. This species is thought to have reached the Knysna Estuary in the early 2000s and has colonised all man-made hard substrata in the embayment of the estuary. Although there are studies on recruitment of M. galloprovincialis on the rocky intertidal coasts of South Africa, there is little information on recruitment of this species in more sheltered estuarine environments. This study aimed to determine recruitment levels of M. galloprovincialis and other bivalves within the Knysna estuarine embayment. To determine monthly recruitment, 10 recruit collectors/pads (plastic pot scourers) were placed at three separate locations within the embayment of the estuary for a week on a monthly basis for 20 months. In addition, recruitment of M. galloprovincialis over spring and neap tides and different lunar phases was also determined at two sites within the Knysna estuarine embayment during the main reproductive season in 2018. The pads were deployed three days before a neap/spring tide and then collected three days after the respective tide. Finally, to look at how rapidly M. galloprovincialis and other macroinvertebrates (when M. galloprovincialis was excluded) would re-colonise free space, 18 plots (15x15 cm), consisting of three treatments including a control (A,B and C), were cleared in M. galloprovincialis mussel beds and then photographed monthly for 12 months. Four bivalve taxa (Mytilus galloprovincialis, Perna perna, Ostreidae, unidentified mytilid) were recorded during the monthly study. Recruitment levels for all bivalves differed significantly (P < 0.001) between months and sites, with peak recruitment occurring from late spring to early autumn (November – March). Mytilus galloprovincialis recruitment levels were greater than other bivalves and were up to 4.5x greater than other taxa. Recruitment also varied between years possibly owing to differences in larval supply and/or environmental factors. Spatial variation in bivalve recruitment was observed throughout the study. The greatest recruitment was at the site (Thesen Island Wharf) closer to the entrance of the embayment. By contrast at the site (Railway Bridge) furthest from the entrance lower recruitment was found. This difference is possibly due to differences in hydrodynamics or other biological and/or environmental factors. A preliminary tidal study found that M. galloprovincialis had significantly higher (P < 0.001) recruitment levels over spring tides than neap tides at Thesen Island Wharf, whereas recruitment at the Railway Bridge on spring and neap tides was not significantly different. In the study undertaken in the reproductive season only, recruitment levels were high over a two week period during both a spring and neap tide, suggesting that factors other than lunar phase and the state of tide are more important in determining the timing and intensity of recruitment. The clearance plots created and photographed over a 12 month period showed that M. galloprovincialis rapidly occupied free space (eight months to virtually cover all free space) by encroachment from the adjacent mussel bed. Limpets and barnacles were only able to colonise cleared space when M. galloprovincialis was excluded, suggesting that the mussel has the ability to outcompete indigenous macrofauna for space. The high recruitment levels of M. galloprovincialis compared to other indigenous bivalves, as well as its ability to occupy space rapidly are traits that must contribute to the success of the invasion of this species within the Knysna estuarine embayment, particulary within Thesen Islands Marina and Thesen Island Wharf.
- Full Text:
- Date Issued: 2019
BODIPY and porphyrin dyes for direct glucose sensing and optical limiting applications
- Authors: Ndebele, Nobuhle
- Date: 2019
- Subjects: Boron compounds , Boric acid , Porphyrins , Dyes and dying -- Chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97221 , vital:31412
- Description: A series of BODIPY dyes functionalised with boronic acid in the 3,5-positions were successfully synthesised and characterised by using various analytical techniques. The dyes were prepared through a slight modification of the conventional acid catalysed condensation method. Phenylboronic acid moieties were added as styryl groups at the 3,5-positions of the 1,3,5,7-tetrametylBODIPY cores using a modified Knoevengal condensation method. The addition of the styryls resulted in the main absorption band of the dyes red-shifting to the 630−650 nm region. The photophysical and electrochemical properties of these dyes were studied to determine whether the dyes are suitable for use in the fluorescent, colourimetric and electrochemical detection of glucose. Boronic acid moieties were added as bioreceptor recognition elements because they have an affinity for carbohydrates and therefore would be able to bind and “detect” glucose. The series of BODIPY dyes did not show a “turn-on” fluorescence effect upon addition with glucose at the physiological pH. This was attributed on the basis of molecular modelling to the absence of an MO localised on the boronic-acid-substituted styryl moieties that lie close in energy to the HOMO and LUMO that facilitates the formation of an intramolecular charge transfer state. However, colourimetric changes that are visible to the naked eye are observed at basic pH when glucose was added to the dye solutions. The dyes exhibited favourable electrochemical behaviour and were able to detect glucose directly in this context when glassy carbon electrodes are modified through the drop dry method. A series of Sn(IV) porphyrins with thienyl and phenyl groups at the meso-positions were successfully synthesised and characterised. Pyridine and tetrabutyl axial ligands were added to the porphyrins to limit aggregation. The optical limiting properties of these porphyrins and three styrylated BODIPY dyes were studied in benzene and dichloromethane. Dyes were also embedded in polystyrene and studied as thin films to further gauge their suitability for use in optical limiting applications. Second-order hyperpolarizability, third-order susceptibly, non-linear absorption with reversible saturable absorption and the optical limiting threshold, were the parameters studied. Three of the four porphyrins and the three styrylated BODIPY dyes showed favourable optical limiting behaviour, which was further enhanced when the dyes are embedded in polymer thin films.
- Full Text:
- Date Issued: 2019
- Authors: Ndebele, Nobuhle
- Date: 2019
- Subjects: Boron compounds , Boric acid , Porphyrins , Dyes and dying -- Chemistry
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/97221 , vital:31412
- Description: A series of BODIPY dyes functionalised with boronic acid in the 3,5-positions were successfully synthesised and characterised by using various analytical techniques. The dyes were prepared through a slight modification of the conventional acid catalysed condensation method. Phenylboronic acid moieties were added as styryl groups at the 3,5-positions of the 1,3,5,7-tetrametylBODIPY cores using a modified Knoevengal condensation method. The addition of the styryls resulted in the main absorption band of the dyes red-shifting to the 630−650 nm region. The photophysical and electrochemical properties of these dyes were studied to determine whether the dyes are suitable for use in the fluorescent, colourimetric and electrochemical detection of glucose. Boronic acid moieties were added as bioreceptor recognition elements because they have an affinity for carbohydrates and therefore would be able to bind and “detect” glucose. The series of BODIPY dyes did not show a “turn-on” fluorescence effect upon addition with glucose at the physiological pH. This was attributed on the basis of molecular modelling to the absence of an MO localised on the boronic-acid-substituted styryl moieties that lie close in energy to the HOMO and LUMO that facilitates the formation of an intramolecular charge transfer state. However, colourimetric changes that are visible to the naked eye are observed at basic pH when glucose was added to the dye solutions. The dyes exhibited favourable electrochemical behaviour and were able to detect glucose directly in this context when glassy carbon electrodes are modified through the drop dry method. A series of Sn(IV) porphyrins with thienyl and phenyl groups at the meso-positions were successfully synthesised and characterised. Pyridine and tetrabutyl axial ligands were added to the porphyrins to limit aggregation. The optical limiting properties of these porphyrins and three styrylated BODIPY dyes were studied in benzene and dichloromethane. Dyes were also embedded in polystyrene and studied as thin films to further gauge their suitability for use in optical limiting applications. Second-order hyperpolarizability, third-order susceptibly, non-linear absorption with reversible saturable absorption and the optical limiting threshold, were the parameters studied. Three of the four porphyrins and the three styrylated BODIPY dyes showed favourable optical limiting behaviour, which was further enhanced when the dyes are embedded in polymer thin films.
- Full Text:
- Date Issued: 2019
Comparison of mesozooplankton communities at three shallow seamounts in the South West Indian Ocean using size spectrum analysis
- Rasoloarijao, Zo, Huggett, Jenny
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
- Authors: Rasoloarijao, Zo , Huggett, Jenny
- Date: 2019
- Subjects: Seamounts
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43012 , vital:36731
- Description: Seamounts influence ocean dynamics and consequently the surrounding ecosystem. Zooplankton communities associated with seamounts may be influenced by various mechanisms related to increased retention,such as Taylor columns and/or enhanced local productivity, leading to increased predation pressure. Through this study we investigated mesozooplankton distribution and community structure in the vicinity of three shallow seamounts in the South West Indian Ocean (SWIO) during September 2016, December 2016 and April/May 2017 at La Pérouse, MadRidge and Walters Shoal respectively. The water-column was profiled at 42 stations using a CTD-F equipped with a L-ADCP and mesozooplankton was sampled with a Bongo net or a Hydrobios Midi MultiNet, both fitted with 200 µm mesh. Walters Shoal had significantly lower mesozooplankton total abundance and biovolume compared to La Perouse and MadRidge. La Perouse and MadRidge showed similar mesozooplankton community structures with steep Normalised Biovolume Size Spectrum (NBSS) slopes, indicating higher productivity and dominance of small organisms, compared to Walters Shoal where the slopes were flatter. Total and per taxon abundances and biovolumes at locations “On” and “Off” the seamount were similar, as was the size diversity for MadRidge and Walter Shoal. None of the environmental parameters tested had a significant effect on variability of the mesozooplankton community structure at the stations overall.
- Full Text:
- Date Issued: 2019
Applications of complex functions on problems in Banach algebras
- Authors: Snyman, Jandré Dillon
- Date: 2019
- Subjects: Banach algebras , Functions of several complex variables
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48643 , vital:41055
- Description: In this dissertation, we provide applications of complex function theory to problems in Banach algebras. We discuss the structure of analytic functions f : D → A, where D is a domain of C and A is a Banach algebra as given by Aupetit in [3]: either the set {λ ∈ D : Sp(f(λ)) is finite} is of capacity zero, or there exists an integer n such that Sp(f(λ)) has exactly n elements, for every λ, except on a closed, discrete set of capacity zero, where the spectrum has at most n−1 elements. This deep result, which describes the structure of Sp(f(λ)) for all λ ∈ D, relies heavily on subharmonic techniques, which are also included in the dissertation. Let A and B be Banach algebras. A linear mapping φ : A → B is called a Jordan homomorphism if and only if φ(xy + yx) = φ(x)φ(y) + φ(y)φ(x) for every x, y ∈ A. This is equivalent to saying that φ(x 2 ) = φ(x) 2 for every x ∈ A. The following problem, due to I. Kaplansky, is still unsolved for the general Banach algebra case: Let A and B be unital Banach algebras and φ : A → B a unital, invertibility preserving linear mapping. Under what conditions of A and B is φ a Jordan homomorphism? The author’s honours project [24] served as an exposition of the GleasonKahane-Żelazko Theorem [7, Theorem 4], which provides an answer to Kaplansky’s problem in the case where B = C. In this dissertation we look at other special cases of Kaplansky’s problem, such as the case where A and B are von Neumann algberas, as solved by Aupetit [4, Theorem 1.3] and remark that his result holds for the more general case where A is any C ∗ -algebra that has the property that every self-adjoint element is the limit of a sequence of linear combinations of orthogonal idempotents in A, and B is a semi-simple Banach algebra. This result relies heavily on complex function theory, spectral theory and holomorphic functional calculus. We also provide detailed expositions of the work of Taylor [27] in which an operator calculus on undounded, closed linear operators is developed, and the work of Allan [1] in which a holomorphic functional calculus is defined for locally convex algebras.
- Full Text:
- Date Issued: 2019
- Authors: Snyman, Jandré Dillon
- Date: 2019
- Subjects: Banach algebras , Functions of several complex variables
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/48643 , vital:41055
- Description: In this dissertation, we provide applications of complex function theory to problems in Banach algebras. We discuss the structure of analytic functions f : D → A, where D is a domain of C and A is a Banach algebra as given by Aupetit in [3]: either the set {λ ∈ D : Sp(f(λ)) is finite} is of capacity zero, or there exists an integer n such that Sp(f(λ)) has exactly n elements, for every λ, except on a closed, discrete set of capacity zero, where the spectrum has at most n−1 elements. This deep result, which describes the structure of Sp(f(λ)) for all λ ∈ D, relies heavily on subharmonic techniques, which are also included in the dissertation. Let A and B be Banach algebras. A linear mapping φ : A → B is called a Jordan homomorphism if and only if φ(xy + yx) = φ(x)φ(y) + φ(y)φ(x) for every x, y ∈ A. This is equivalent to saying that φ(x 2 ) = φ(x) 2 for every x ∈ A. The following problem, due to I. Kaplansky, is still unsolved for the general Banach algebra case: Let A and B be unital Banach algebras and φ : A → B a unital, invertibility preserving linear mapping. Under what conditions of A and B is φ a Jordan homomorphism? The author’s honours project [24] served as an exposition of the GleasonKahane-Żelazko Theorem [7, Theorem 4], which provides an answer to Kaplansky’s problem in the case where B = C. In this dissertation we look at other special cases of Kaplansky’s problem, such as the case where A and B are von Neumann algberas, as solved by Aupetit [4, Theorem 1.3] and remark that his result holds for the more general case where A is any C ∗ -algebra that has the property that every self-adjoint element is the limit of a sequence of linear combinations of orthogonal idempotents in A, and B is a semi-simple Banach algebra. This result relies heavily on complex function theory, spectral theory and holomorphic functional calculus. We also provide detailed expositions of the work of Taylor [27] in which an operator calculus on undounded, closed linear operators is developed, and the work of Allan [1] in which a holomorphic functional calculus is defined for locally convex algebras.
- Full Text:
- Date Issued: 2019
Effect of dietary Mucuna pruriens seed meal on the serum lipid profile and bone quality traits of broiler chickens
- Authors: Hempe, Chumani
- Date: 2019
- Subjects: Legumes Lipoproteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17213 , vital:40866
- Description: This study aimed at evaluating the effects of heated Mucuna pruriens seed meal on the blood serum lipid profile and bone quality parameters of broiler chickens. A total of 120 day-old unsexed Cobb 500 broiler chicks were randomly allocated for the 4 treatment diets (T1, T2, T3 and T4) containing 0, 10, 15, and 20% heated Mucuna pruriens seed meal. The birds were reared on wood shaving floor pens for 35 days. Birds were humanely slaughtered by severing the jugular vein using a sharp knife. Blood was collected into a tube, centrifuge and analyzed for a lipid profile analysis (total cholesterol (TC), high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides (TCD) as well as aspartate transaminase (AST) and alanine transaminase (ALT)) by enzymatic diagnostic kits (Diasys diagnostic kits). Both drumsticks severed using a sharp knife. After boiling in the water at 100°C for 10 mins the tibia bones were taken, air-dried for 96 hrs at room temperature and measured for weights. Bone length, strength, moisture and ash content as well as morphology were measured. The blood lipid profile of birds fed T1 was high (P < 0.05) for all the parameters measured, while T3 had the lowest (P < 0.05) profile. T2 and T4 had the same profile. ALT was found to be highest (P < 0.05) for T4 (5.27 ± 0.207/L) and lowest (P < 0.05) for T2 (4.67 ± 0.333/L) while AST was highest (P < 0.05) for T2 (320.13 ± 28.851/L) and lowest (P < 0.05) for T3 (208.47 ± 10.059/L). Treatment diet 3 (T3) was observed decreased bone quality among all diets; with the lowest (P < 0.05) bone strength (188.55 ± 12.039N), bone length (8.59 ± 0.131cm) and morphology (1.69 ± 0.058). Mucuna pruriens seed meal inclusion in broiler diets reduces blood serum lipids and 20% inclusion levels have no adverse effects on the bone quality attributes
- Full Text:
- Date Issued: 2019
- Authors: Hempe, Chumani
- Date: 2019
- Subjects: Legumes Lipoproteins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/17213 , vital:40866
- Description: This study aimed at evaluating the effects of heated Mucuna pruriens seed meal on the blood serum lipid profile and bone quality parameters of broiler chickens. A total of 120 day-old unsexed Cobb 500 broiler chicks were randomly allocated for the 4 treatment diets (T1, T2, T3 and T4) containing 0, 10, 15, and 20% heated Mucuna pruriens seed meal. The birds were reared on wood shaving floor pens for 35 days. Birds were humanely slaughtered by severing the jugular vein using a sharp knife. Blood was collected into a tube, centrifuge and analyzed for a lipid profile analysis (total cholesterol (TC), high density lipoproteins (HDL), low density lipoproteins (LDL), triglycerides (TCD) as well as aspartate transaminase (AST) and alanine transaminase (ALT)) by enzymatic diagnostic kits (Diasys diagnostic kits). Both drumsticks severed using a sharp knife. After boiling in the water at 100°C for 10 mins the tibia bones were taken, air-dried for 96 hrs at room temperature and measured for weights. Bone length, strength, moisture and ash content as well as morphology were measured. The blood lipid profile of birds fed T1 was high (P < 0.05) for all the parameters measured, while T3 had the lowest (P < 0.05) profile. T2 and T4 had the same profile. ALT was found to be highest (P < 0.05) for T4 (5.27 ± 0.207/L) and lowest (P < 0.05) for T2 (4.67 ± 0.333/L) while AST was highest (P < 0.05) for T2 (320.13 ± 28.851/L) and lowest (P < 0.05) for T3 (208.47 ± 10.059/L). Treatment diet 3 (T3) was observed decreased bone quality among all diets; with the lowest (P < 0.05) bone strength (188.55 ± 12.039N), bone length (8.59 ± 0.131cm) and morphology (1.69 ± 0.058). Mucuna pruriens seed meal inclusion in broiler diets reduces blood serum lipids and 20% inclusion levels have no adverse effects on the bone quality attributes
- Full Text:
- Date Issued: 2019
Determination of social, environmental and economic benefits for community participation in forestry in Mpumalanga, South Africa
- Long, Leo Searle, Chirwa, Paxie
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
- Authors: Long, Leo Searle , Chirwa, Paxie
- Date: 2019
- Subjects: Forests and forestry -- South Africa -- Mpumalanga
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34339 , vital:33307
- Description: Rural communities living adjacent to commercial forestry operations are often affected by numerous negative social issues such as poverty, unemployment, poor healthcare, and limited infrastructure, amongst others. In excess of 61% of forestry land managed by the state owned SAFCOL SOC Ltd is under land claim, as part of the Restitution of Land Rights Act (Act 22 of 1994). It is therefore necessary for forest companies to seek active means of engaging and partnering with these communities through a participatory forest management (PFM) approach. This study explored the sustainable (social, environmental and economic), benefits of such an approach as perceived (experienced) by these local rural communities, and specifically land claimants. The study was conducted in communities adjacent to SAFCOL plantations in the Mpumalanga Province of South Africa. Data were collected between May and June 2017 by means of a structured questionnaire. Surveys were conducted on 46 households within the identified communities so as to verify and evaluate perceived benefits in terms of forest products, ecosystem services and amenities/services/infrastructure provided by SAFCOL and the broader forest industry. The results indicated that these communities recognize and obtain numerous social, environmental and economic benefits from the forest including Non-Timber Forest Products (NTFPs) such as firewood; forest provisioning ecosystem services (FPESs) such as improved water quality; and more metaphysical benefits such as access to gravesites and the protection of traditions and customs. These benefits have the ability to improve the social well-being, economic independence, and the quality of environmental services obtained by the associated communities. It was however found that the utilization of these benefits was widely differentiated according to gender and land claimant status. Whilst males and females largely benefitted equally, there was a distinct benefit preference between genders for different NTFPs. For example males showed preference for the collection of building material, bush meat and for livestock husbandry, whilst females showed preference for the collection of firewood, medicinal plants and fruit, amongst others. Similarly, it was found that overall, non-land claimants benefited more than land claimants. Reasons for this are primarily due to the increased distance with which the land claimants live from the forest resource when compared to non-land claimants. The empirical value of the data produced through this study will be invaluable in negotiations with the land claimant communities on land settlement agreements, joint venture proposals, including Participatory Forest Management, and future land tenure. Through such inclusivity and vested interest in the sustainable management of the forests, corporate risk is reduced and community/land claimant relationships are reinforced. Such Participatory Forest Management arrangements are key to ensuring the longevity and resilience to the forest sector post-transfer of claimed land.
- Full Text:
- Date Issued: 2019
Improving the property rental market in Tshwane CBD
- Authors: Kganyago, Rapholo Joseph
- Date: 2019
- Subjects: Real property -- South Africa -- Pretoria , Rental housing -- South Africa -- Pretoria Building leases -- South Africa -- Pretoria Housing -- South Africa -- Pretoria
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40588 , vital:36185
- Description: The research focuses on investigating the Improvement of the property rental market in Tshwane CBD. This includes determining the factors leading to high dilapidation of the Tshwane rental properties in its CBD as well as establishing the challenges experienced by the tenants in respect to the comfort and safety of their rented properties. This includes determining challenges faced by the rental property owners in establishing safe, comfortable housing facilities that fulfill the tenants’ expectations. The research further determines to illuminate on economic opportunities that can be realised in improving the conditions of the rental property market. The research employs a mixed research approach, where 100 survey participants and 10 qualitative interviewees are used to gather empirical evidence for the study. This manages to bring congruency to the outcomes of the study. The research finds that rent seeking behaviours are prevalent in the Tshwane rental property market. The study finds that there is lack of adequate management of rental properties owing to challenges with timely maintenance costs that affect most rented properties in the CBD. The research illuminates further that rental property owners and employed agencies are not effectively upgrading or modifying security features in their commercialized units much to diminished safety of property and most importantly the tenants. The research also exposes that foreign nationals in rental property market are also part of the rent-seeking behaviours through some hidden costs and penalties that do not align with local authority regulations to unsuspecting and prospective tenants much like local rental property stakeholders. The research has recommended that regulatory agencies in the rental property market must be trained and assessed on performance metrics continuously to ensure that they effectively address and expose issues such as latent defects, health inspections of properties and a better understanding of rental property dynamics at inspection and certification of rental units as fit for commercial business. The research further recommends that urbanisation through gentrification requires sustainable partnerships between both private and public construction sector players with adequate consultation with communities affected near CBDs to encourage building of more structures that are affordable to middle-income earners residing in affected rental areas identified in the research phenomenon.
- Full Text:
- Date Issued: 2019
- Authors: Kganyago, Rapholo Joseph
- Date: 2019
- Subjects: Real property -- South Africa -- Pretoria , Rental housing -- South Africa -- Pretoria Building leases -- South Africa -- Pretoria Housing -- South Africa -- Pretoria
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/40588 , vital:36185
- Description: The research focuses on investigating the Improvement of the property rental market in Tshwane CBD. This includes determining the factors leading to high dilapidation of the Tshwane rental properties in its CBD as well as establishing the challenges experienced by the tenants in respect to the comfort and safety of their rented properties. This includes determining challenges faced by the rental property owners in establishing safe, comfortable housing facilities that fulfill the tenants’ expectations. The research further determines to illuminate on economic opportunities that can be realised in improving the conditions of the rental property market. The research employs a mixed research approach, where 100 survey participants and 10 qualitative interviewees are used to gather empirical evidence for the study. This manages to bring congruency to the outcomes of the study. The research finds that rent seeking behaviours are prevalent in the Tshwane rental property market. The study finds that there is lack of adequate management of rental properties owing to challenges with timely maintenance costs that affect most rented properties in the CBD. The research illuminates further that rental property owners and employed agencies are not effectively upgrading or modifying security features in their commercialized units much to diminished safety of property and most importantly the tenants. The research also exposes that foreign nationals in rental property market are also part of the rent-seeking behaviours through some hidden costs and penalties that do not align with local authority regulations to unsuspecting and prospective tenants much like local rental property stakeholders. The research has recommended that regulatory agencies in the rental property market must be trained and assessed on performance metrics continuously to ensure that they effectively address and expose issues such as latent defects, health inspections of properties and a better understanding of rental property dynamics at inspection and certification of rental units as fit for commercial business. The research further recommends that urbanisation through gentrification requires sustainable partnerships between both private and public construction sector players with adequate consultation with communities affected near CBDs to encourage building of more structures that are affordable to middle-income earners residing in affected rental areas identified in the research phenomenon.
- Full Text:
- Date Issued: 2019
Vulnerability in surf tourism: surf break decline and its impact on Herold's Bay, South Africa
- Authors: Schröder, Klaus
- Date: 2019
- Subjects: Surfing -- South Africa , Tourism -- Environmental aspects Climatic changes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43501 , vital:36900
- Description: Surfing has increasingly become a mainstream and demographically diverse activity that holds substantial economic worth. It also holds substantial social, cultural and spiritual value for participants and related communities. It is therefore not surprising that the maintenance of surf breaks has become an important element of coastal tourism, and that tourism management has had a growing concern with anthropogenic impacts on the shoreline. In line with these developments, this study investigates the vulnerability of surf tourism given the general consensus that there has been a human-induced decline of the river-mouth surf break in Herold’s Bay. An adapted ecological services model is used, and in line with such models, the status of the three types of capital (natural (physical) capital, climatic capital, and built capital) and their effect on recreation capital (surfing’s participation, market, and non-market values) over a twenty-year period is tracked. The findings identified alterations to the river bed morphology, beach morphology, wind direction, and swell intensity and frequency as the main determinants in surf break decline. The corresponding increase in vulnerability of Herold’s Bay’s surf tourism industry is also given as having negative socio-economic impacts. This study has underlined both the potential and the imperative to conserve, utilise and develop surf breaks and the surf tourism industry within South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Schröder, Klaus
- Date: 2019
- Subjects: Surfing -- South Africa , Tourism -- Environmental aspects Climatic changes -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/43501 , vital:36900
- Description: Surfing has increasingly become a mainstream and demographically diverse activity that holds substantial economic worth. It also holds substantial social, cultural and spiritual value for participants and related communities. It is therefore not surprising that the maintenance of surf breaks has become an important element of coastal tourism, and that tourism management has had a growing concern with anthropogenic impacts on the shoreline. In line with these developments, this study investigates the vulnerability of surf tourism given the general consensus that there has been a human-induced decline of the river-mouth surf break in Herold’s Bay. An adapted ecological services model is used, and in line with such models, the status of the three types of capital (natural (physical) capital, climatic capital, and built capital) and their effect on recreation capital (surfing’s participation, market, and non-market values) over a twenty-year period is tracked. The findings identified alterations to the river bed morphology, beach morphology, wind direction, and swell intensity and frequency as the main determinants in surf break decline. The corresponding increase in vulnerability of Herold’s Bay’s surf tourism industry is also given as having negative socio-economic impacts. This study has underlined both the potential and the imperative to conserve, utilise and develop surf breaks and the surf tourism industry within South Africa.
- Full Text:
- Date Issued: 2019
Bootstrap-based tolerance intervals for photovoltaic energy yield assessments
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019
- Authors: Deyzel, Jani Igna
- Date: 2019
- Subjects: Bootstrap (Statistics) , Mathematical statistics Photovoltaic power systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/39469 , vital:35256
- Description: The assessment of the energy yield of a photovoltaic (PV) system is one of the key assessments required by investors and developers. Currently, available methods used for this assessment only provide a point estimate as the final assessment. This study proposes a statistical technique which provides an additional energy yield assessment method by using tolerance intervals. Variance component models are used to better account for the variability present in the daily and hourly energy yields of three different PV modules. A bootstrap-based technique is used to obtain 𝛽-expectation and (𝛼,𝛽) two-sided tolerance intervals. These tolerance intervals provided more information with a content and confidence level for seasonal and yearly time-periods. In addition, the comparisons of the PV modules provide valuable information to investors and developers.
- Full Text:
- Date Issued: 2019