An investigation into the fire regimes of the upper Tsitsa River catchment
- Authors: Snyman, Gareth
- Date: 2020
- Subjects: Prescribed burning -- Environmental aspects -- South Africa , Fire ecology -- South Africa , Tsitsa River catchment (South Africa) , Soil erosion -- South Africa , Grasslands -- Management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/145256 , vital:38422
- Description: South African grasslands are rich in flora and fauna and are a dominant vegetation cover in many of the water catchment areas, while providing a multitude of services to local communities and the environment. Fires have been the primary tool used to manage grasslands for livestock production for many years. However, there is debate about how they impact and alter landscapes and there are two schools of thought throughout literature. One argument is that fires are detrimental to landscapes; altering hydrological processes by causing excess soil erosion and changing soil properties. The other opinion is that fires are beneficial to ecosystems; maintaining vegetation structure, preventing bush encroachment, cycling nutrients and allowing for new plant growth. This study focused on the effects of fire regimes on soil properties in order to better understand the role that fire plays in geomorphic processes in the upper Tsitsa River catchment. The catchment falls under two land management types- commercial and communal, with the latter being severely degraded. Fire regimes were determined using a combination of Landsat and MODIS remotely sensed data and testing was carried out on soils exposed to different Fire Return Intervals (FRI). It was found that soils that were exposed to a high fire frequency (1-2-year FRI) exhibited a significantly higher degree of water repellency (p< 0.001) and surface hardness (p< 0.001) than soils that were exposed to a low fire frequency (3-4 year FRI), which indicates increased erosion potential. However, whilst a higher fire frequency resulted in altered soil characteristics, it contributed to landscape degradation as suggested in the literature, and soils are able to return to their previous state in over a short period of time. Further investigation into factors affecting fire regimes found that geology influenced vegetation type, resulting in differences in biomass in the two land management areas. The commercially managed land supported a high biomass, which resulted in a more natural fire regime with frequent fires, whilst the communally managed land supported less biomass. Smaller fuel loads and increased landscape fragmentation through overgrazing and road networks resulted in an altered fire regime with less frequent fires. Although the communally managed land has an altered fire regime, this research suggests that fires are not influencing the severe degradation present in these areas, and this is rather a function of geology and mismanagement of land. Whilst fire and grazing management plans can be implemented to alter the modified fire regime in the communal areas back to its natural state, this would take a long time and an increase in fires would pose a threat to surrounding communities. Overall the fire regimes in the upper Tsitsa River catchment are being altered by human influence and land management type, and whilst fire frequency is negatively altering soil properties, these soils can return to their natural state. The severe land degradation present in the communally managed areas are not a function of fire frequency and rather of geology and land management.
- Full Text:
- Date Issued: 2020
- Authors: Snyman, Gareth
- Date: 2020
- Subjects: Prescribed burning -- Environmental aspects -- South Africa , Fire ecology -- South Africa , Tsitsa River catchment (South Africa) , Soil erosion -- South Africa , Grasslands -- Management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/145256 , vital:38422
- Description: South African grasslands are rich in flora and fauna and are a dominant vegetation cover in many of the water catchment areas, while providing a multitude of services to local communities and the environment. Fires have been the primary tool used to manage grasslands for livestock production for many years. However, there is debate about how they impact and alter landscapes and there are two schools of thought throughout literature. One argument is that fires are detrimental to landscapes; altering hydrological processes by causing excess soil erosion and changing soil properties. The other opinion is that fires are beneficial to ecosystems; maintaining vegetation structure, preventing bush encroachment, cycling nutrients and allowing for new plant growth. This study focused on the effects of fire regimes on soil properties in order to better understand the role that fire plays in geomorphic processes in the upper Tsitsa River catchment. The catchment falls under two land management types- commercial and communal, with the latter being severely degraded. Fire regimes were determined using a combination of Landsat and MODIS remotely sensed data and testing was carried out on soils exposed to different Fire Return Intervals (FRI). It was found that soils that were exposed to a high fire frequency (1-2-year FRI) exhibited a significantly higher degree of water repellency (p< 0.001) and surface hardness (p< 0.001) than soils that were exposed to a low fire frequency (3-4 year FRI), which indicates increased erosion potential. However, whilst a higher fire frequency resulted in altered soil characteristics, it contributed to landscape degradation as suggested in the literature, and soils are able to return to their previous state in over a short period of time. Further investigation into factors affecting fire regimes found that geology influenced vegetation type, resulting in differences in biomass in the two land management areas. The commercially managed land supported a high biomass, which resulted in a more natural fire regime with frequent fires, whilst the communally managed land supported less biomass. Smaller fuel loads and increased landscape fragmentation through overgrazing and road networks resulted in an altered fire regime with less frequent fires. Although the communally managed land has an altered fire regime, this research suggests that fires are not influencing the severe degradation present in these areas, and this is rather a function of geology and mismanagement of land. Whilst fire and grazing management plans can be implemented to alter the modified fire regime in the communal areas back to its natural state, this would take a long time and an increase in fires would pose a threat to surrounding communities. Overall the fire regimes in the upper Tsitsa River catchment are being altered by human influence and land management type, and whilst fire frequency is negatively altering soil properties, these soils can return to their natural state. The severe land degradation present in the communally managed areas are not a function of fire frequency and rather of geology and land management.
- Full Text:
- Date Issued: 2020
Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Mur amide ligases , Ligases , Ligand binding (Biochemistry) , Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163430 , vital:41036
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Mur amide ligases , Ligases , Ligand binding (Biochemistry) , Antibacterial agents
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163430 , vital:41036
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
Analysis of bacterial Mur amide ligase enzymes for the identification of inhibitory compounds by in silico methods
- Chamboko, Chiratidzo Respina
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
- Authors: Chamboko, Chiratidzo Respina
- Date: 2020
- Subjects: Pathogenic microorganisms -- Analysis , Drug resistance in microorganisms , Microorganisms -- Effect of drugs on , Antibiotics -- Effectiveness , Pathogenic bacteria , Drug tolerance , Enzymes -- Analysis , Peptide antibiotics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/161911 , vital:40690
- Description: An increased emergence of resistant pathogenic bacterial strains over the years has resulted in many people dying of untreatable infections. This has become one of the most critical global public health problems, as resistant strains are complicating treatment of infectious diseases, increasing human morbidity, mortality, and health care costs. A very limited amount of effective antibiotics is currently available, but the development of novel classes of antibacterial agents is becoming a priority. Mur amide ligases are enzymes that have been identified as potentially good targets for antibiotics, as they are uniquely found in bacteria. They are responsible for the formation of peptide bonds in a growing peptidoglycan structure for bacterial cell walls. The current work presented here focused on characterizing these Mur amide ligase enzymes and obtaining inhibitory compounds that could potentially be of use in drug discovery of antibacterial agents. To do this, multiple sequence alignment, motif analysis and phylogenetic tree constructions were carried out, followed by docking studies and molecular dynamic simulations. Prior to docking, homology modelling of missing residues in the MurF structure (PDB 1GG4) was performed. Characterization results revealed the Mur amide ligase enzymes contained defined conservation in limited regions, that ultimately mapped towards the central domain responsible for ATP binding (presence of a conserved GKT motif). Further analysis of results further unraveled the unique patterns observed within each group of the family of enzymes. As a result of these findings, docking studies were carried out on each Mur amide ligase structure. At most, two ligands were identified to be sufficiently inhibiting each Mur amide ligase. The ligands obtained were SANC00574 and SANC00575 for MurC, SANC00290 and SANC00438 for MurD, SANC00290 and SANC00525 for MurE and SANC00290 and SANC00434 for MurF. The two best ligands identified for each enzyme had docked in the active site of their respective proteins, passed Lipinski’s rule of five and had substantially low binding energies. Molecular dynamic simulations were then performed to analyze the behavior of the proteins and protein-ligand complexes, to confirm the lead compounds as good inhibitors of the Mur amide ligases. In the case of MurC, MurD and MurE complexes, the identified ligands clearly impacted the behavior of the protein, as the ligand bound proteins became more compact and stable, while flexibility decreased. There was however an opposite effect on MurF complexes, that resulted in identified inhibitors being discarded. As a potential next step, in vivo and in vitro experiments can be performed with identified ligands from this research, to further support the information presented.
- Full Text:
- Date Issued: 2020
Social media big data: a diary study of ten pharmaceutical firms
- Authors: Baker, Nadia Samantha
- Date: 2020
- Subjects: Big data , Internet in medicine , Social media in medicine , Internet marketing -- Evaluation , Pharmacy management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/140737 , vital:37914
- Description: Purpose: The goal of the research was to demonstrate how firms can use social media big data, to make strategic business decisions, through the lens of Resource Based Theory (RBT) and Dynamic Capability Theory (DCT), that could lead to a sustained competitive advantage. In and of its own, big data, does not constitute a competitive advantage. It may hold value for the firm, but lacks rarity, inimitability, and is not substitutable (Braganza, et al. 2017; Mata, Fuerst and Barney, 1995; Delmonte, 2003). It is in the analysis of this data, through RBT and DCT, that will turn the information into useful business intelligence (Amit and Schoemaker, 1993; Barney, 1991; 1995; Marr, 2015; Gupta and George, 2016; Kurtmollaiev, et al., 2018). Most importantly, firms must constantly reconfigure their resources in line with the dynamic business environment to ensure superior performance (Teece, Pisano and Shuen, 1997; Helfat, et al., 2007; Teece, 2014; 2018). Method: In this study, a qualitative approach was used to examine the RBT (Value, Rarity, Inimitability and Non-Substitutable - VRIN Framework) and DCT, to describe and understand the relevant theories and to build upon the quantitative results. While a quantitative approach was used to analyse the social media sentiment as depicted by Social Mention metrics. A novel technique, Chernoff Faces, was used to analyse and visualize the data (de Vos, Strydom, Fouche and Delport, 2011). Results and Findings: The research results show that, while the 10 firms in the study all have a presence on social media, it is on selective platforms. The content that is posted, is on very specific topics (Narayan, 2017; Cornejo, 2018). The Chernoff Faces indicate that the firms’ Social Mention metrics, over the 30 day period, was at low values. Since strength of social mention is depicted by the face line, the thin, long, generally sad looking faces implies that more than 70 percent of the firms’ social media strength over the study period, was weak. Conclusion: The literature indicates that the true value of big data and big data analytics can only be realised if firms make sound business decisions and act upon it swiftly.
- Full Text:
- Date Issued: 2020
- Authors: Baker, Nadia Samantha
- Date: 2020
- Subjects: Big data , Internet in medicine , Social media in medicine , Internet marketing -- Evaluation , Pharmacy management -- South Africa
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/140737 , vital:37914
- Description: Purpose: The goal of the research was to demonstrate how firms can use social media big data, to make strategic business decisions, through the lens of Resource Based Theory (RBT) and Dynamic Capability Theory (DCT), that could lead to a sustained competitive advantage. In and of its own, big data, does not constitute a competitive advantage. It may hold value for the firm, but lacks rarity, inimitability, and is not substitutable (Braganza, et al. 2017; Mata, Fuerst and Barney, 1995; Delmonte, 2003). It is in the analysis of this data, through RBT and DCT, that will turn the information into useful business intelligence (Amit and Schoemaker, 1993; Barney, 1991; 1995; Marr, 2015; Gupta and George, 2016; Kurtmollaiev, et al., 2018). Most importantly, firms must constantly reconfigure their resources in line with the dynamic business environment to ensure superior performance (Teece, Pisano and Shuen, 1997; Helfat, et al., 2007; Teece, 2014; 2018). Method: In this study, a qualitative approach was used to examine the RBT (Value, Rarity, Inimitability and Non-Substitutable - VRIN Framework) and DCT, to describe and understand the relevant theories and to build upon the quantitative results. While a quantitative approach was used to analyse the social media sentiment as depicted by Social Mention metrics. A novel technique, Chernoff Faces, was used to analyse and visualize the data (de Vos, Strydom, Fouche and Delport, 2011). Results and Findings: The research results show that, while the 10 firms in the study all have a presence on social media, it is on selective platforms. The content that is posted, is on very specific topics (Narayan, 2017; Cornejo, 2018). The Chernoff Faces indicate that the firms’ Social Mention metrics, over the 30 day period, was at low values. Since strength of social mention is depicted by the face line, the thin, long, generally sad looking faces implies that more than 70 percent of the firms’ social media strength over the study period, was weak. Conclusion: The literature indicates that the true value of big data and big data analytics can only be realised if firms make sound business decisions and act upon it swiftly.
- Full Text:
- Date Issued: 2020
Environmental drivers of the composition and distribution of larval fish assemblages off the south coast of South Africa
- Authors: Trassierra, Jaqueline Anne
- Date: 2019
- Subjects: Fishes -- Larvae -- South Africa -- Eastern Cape , Fishes -- Larvae -- Migration -- South Africa -- Eastern Cape , Fishes -- Larvae -- Dispersal -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68154 , vital:29207
- Description: The species composition, distribution and patterns of vertical migration of larval fish assemblages were investigated in March and in September 2013 within two adjacent log spiral bays, Algoa Bay and St Francis Bay, on the south coast of South Africa. Fish larvae were collected by means of a boat towed bongo net (57 cm diameter; mesh aperture 500 μm). An onshore (2 km) and an offshore (3 km) station were each sampled twice during the daytime (06:00 – 18:00) with two horizontal tows: near the surface (0.5 m) and close to the bottom (12 m). Tows were repeated at night (18:00 – 23:00) for onshore sites. Larval catches included 16 fish families and 40 species. A multivariate analysis indicated that the species composition was significantly different between Algoa Bay and St Francis Bay, with Engraulidae, Blenniidae, Sparidae, Soleidae and Cynoglossidae making important contributions to the larval fish catch in Algoa Bay, while Blenniidae, Engraulidae, Tripterygiidae, Sparidae and Gobiesocidae contributed significantly in St Francis Bay. Differences in assemblage composition were noted between the Spring (September–October) and Autumn (March-April) months. The species composition of larval fish assemblages was related to wind speed, wave height, cloud cover, sea water temperature, depth, average current speed and direction. Wind speed, wave height, temperature and depth significantly contributed to the variation in larval fish densities. Abundances of larval fishes were greater offshore than onshore, larvae from pelagic eggs dominated catches offshore, while larvae from demersal eggs dominated onshore catches. Habitat structure strongly influenced the composition of larval fishes between the bays and abundances were significantly greater at night than during the day. Most larval fishes displayed a reverse diel vertical migration pattern and were most influenced by predators, wind speed and cloud cover. This study shows that larval fish assemblages are highly complex and patchy. Spawning mode, individual species behaviour, diel vertical migration, current structure, depth, temperature, wind speed, cloud cover and type of habitat substratum all influence larval fish composition and distribution in the nearshore waters of South Africa.
- Full Text:
- Date Issued: 2019
- Authors: Trassierra, Jaqueline Anne
- Date: 2019
- Subjects: Fishes -- Larvae -- South Africa -- Eastern Cape , Fishes -- Larvae -- Migration -- South Africa -- Eastern Cape , Fishes -- Larvae -- Dispersal -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/68154 , vital:29207
- Description: The species composition, distribution and patterns of vertical migration of larval fish assemblages were investigated in March and in September 2013 within two adjacent log spiral bays, Algoa Bay and St Francis Bay, on the south coast of South Africa. Fish larvae were collected by means of a boat towed bongo net (57 cm diameter; mesh aperture 500 μm). An onshore (2 km) and an offshore (3 km) station were each sampled twice during the daytime (06:00 – 18:00) with two horizontal tows: near the surface (0.5 m) and close to the bottom (12 m). Tows were repeated at night (18:00 – 23:00) for onshore sites. Larval catches included 16 fish families and 40 species. A multivariate analysis indicated that the species composition was significantly different between Algoa Bay and St Francis Bay, with Engraulidae, Blenniidae, Sparidae, Soleidae and Cynoglossidae making important contributions to the larval fish catch in Algoa Bay, while Blenniidae, Engraulidae, Tripterygiidae, Sparidae and Gobiesocidae contributed significantly in St Francis Bay. Differences in assemblage composition were noted between the Spring (September–October) and Autumn (March-April) months. The species composition of larval fish assemblages was related to wind speed, wave height, cloud cover, sea water temperature, depth, average current speed and direction. Wind speed, wave height, temperature and depth significantly contributed to the variation in larval fish densities. Abundances of larval fishes were greater offshore than onshore, larvae from pelagic eggs dominated catches offshore, while larvae from demersal eggs dominated onshore catches. Habitat structure strongly influenced the composition of larval fishes between the bays and abundances were significantly greater at night than during the day. Most larval fishes displayed a reverse diel vertical migration pattern and were most influenced by predators, wind speed and cloud cover. This study shows that larval fish assemblages are highly complex and patchy. Spawning mode, individual species behaviour, diel vertical migration, current structure, depth, temperature, wind speed, cloud cover and type of habitat substratum all influence larval fish composition and distribution in the nearshore waters of South Africa.
- Full Text:
- Date Issued: 2019
Identification of possible natural compounds as potential inhibitors against Plasmodium M1 alanyl aminopeptidase
- Soliman, Omar Samir Abdel Ghaffar
- Authors: Soliman, Omar Samir Abdel Ghaffar
- Date: 2019
- Subjects: Plasmodium , Malaria -- Chemotherapy , Plasmodium -- Inhibitors , Drug resistance in microorganisms , Aminopeptidases
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72284 , vital:30026
- Description: Malaria is a major tropical health problem with a 29% mortality rate among people of all ages; it also affects 35% of the children. Despite the decrease in mortality rate in recent years, malaria still results in around 2000 deaths per day. Malaria is caused by Plasmodium parasites and is transmitted to humans via the bites from infected female Anopheles mosquitoes during blood meals. There are five different Plasmodium species that can cause human malaria, which include Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale and Plasmodium knowlesi. Among these five species, the most pathogenic ones are Plasmodium falciparum and Plasmodium vivax. Malaria is usually hard to diagnose because the symptoms are not exclusive to malaria and very similar to flu, e.g., fever, muscle pain, and chills, which lead to the misdiagnosis of malaria cases. Malaria is lethal if not treated because it can cause severe complications in the respiratory tract, liver, metabolic acidosis, and hypoglycemia. The malaria parasite life cycle includes two types of hosts, i.e., a human host and female Anopheles mosquito host. Malaria continuously develops resistance to the available drugs, which is one of the major challenges in disease control. This situation confirms the need to develop new drugs that target virulence factors of malaria. The malarial parasite has three main life cycle stages, which include the host liver stage, host blood stage and vector stage. In the blood stage, parasites degrade hemoglobin to amino acids, which is important as these parasites cannot produce their own amino acids. Different proteases are involved in this hemoglobin degradation process. M1 alanyl aminopeptidase is one of these proteases involved at the end of hemoglobin degradation. This study focused on M1 alanyl aminopeptidase as a potential drug target. M1 alanyl aminopeptidase consists of four domains: N-terminal domain, catalytic domain, middle domain and C-terminal domain. The catalytic domain remains conserved among different Plasmodium species. Inhibition of this enzyme might prevent Plasmodium growth as it can’t produce its own amino acids. In this study, sequence analysis was carried out in both human and Plasmodium M1 alanyl aminopeptidase to identify conserved and divergent regions between them. 3D protein models of the M1 alanyl aminopeptidase from Plasmodium species were built and validated. Then the generated models were used for virtual screening against 623 compounds retrieved from the South African Natural Compounds Database (SANCDB, https://sancdb.rubi.ru.ac.za/). Virtual screening was done using blind and targeted docking methods. Docking was used to identify compounds with selective high binding affinity to the active site of the parasite protein. In this study, one SANCDB compound was selected for each protein: SANC00531 was selected against P. falciparum M1 alanyl aminopeptidase, SANC00469 against P. knowlesi, SANC00660 against P. vivax, SANC00144 against P. ovale and SANC00109 against P. malariae. It was found that Plamsodium M1 alanyl aminopeptidase can be used as a potential drug target as it showed selective binding against different inhibitor compounds. This result will be investigated in future work though molecular dynamic analysis to investigate the stability of protein-ligand complexes.
- Full Text:
- Date Issued: 2019
- Authors: Soliman, Omar Samir Abdel Ghaffar
- Date: 2019
- Subjects: Plasmodium , Malaria -- Chemotherapy , Plasmodium -- Inhibitors , Drug resistance in microorganisms , Aminopeptidases
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/72284 , vital:30026
- Description: Malaria is a major tropical health problem with a 29% mortality rate among people of all ages; it also affects 35% of the children. Despite the decrease in mortality rate in recent years, malaria still results in around 2000 deaths per day. Malaria is caused by Plasmodium parasites and is transmitted to humans via the bites from infected female Anopheles mosquitoes during blood meals. There are five different Plasmodium species that can cause human malaria, which include Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale and Plasmodium knowlesi. Among these five species, the most pathogenic ones are Plasmodium falciparum and Plasmodium vivax. Malaria is usually hard to diagnose because the symptoms are not exclusive to malaria and very similar to flu, e.g., fever, muscle pain, and chills, which lead to the misdiagnosis of malaria cases. Malaria is lethal if not treated because it can cause severe complications in the respiratory tract, liver, metabolic acidosis, and hypoglycemia. The malaria parasite life cycle includes two types of hosts, i.e., a human host and female Anopheles mosquito host. Malaria continuously develops resistance to the available drugs, which is one of the major challenges in disease control. This situation confirms the need to develop new drugs that target virulence factors of malaria. The malarial parasite has three main life cycle stages, which include the host liver stage, host blood stage and vector stage. In the blood stage, parasites degrade hemoglobin to amino acids, which is important as these parasites cannot produce their own amino acids. Different proteases are involved in this hemoglobin degradation process. M1 alanyl aminopeptidase is one of these proteases involved at the end of hemoglobin degradation. This study focused on M1 alanyl aminopeptidase as a potential drug target. M1 alanyl aminopeptidase consists of four domains: N-terminal domain, catalytic domain, middle domain and C-terminal domain. The catalytic domain remains conserved among different Plasmodium species. Inhibition of this enzyme might prevent Plasmodium growth as it can’t produce its own amino acids. In this study, sequence analysis was carried out in both human and Plasmodium M1 alanyl aminopeptidase to identify conserved and divergent regions between them. 3D protein models of the M1 alanyl aminopeptidase from Plasmodium species were built and validated. Then the generated models were used for virtual screening against 623 compounds retrieved from the South African Natural Compounds Database (SANCDB, https://sancdb.rubi.ru.ac.za/). Virtual screening was done using blind and targeted docking methods. Docking was used to identify compounds with selective high binding affinity to the active site of the parasite protein. In this study, one SANCDB compound was selected for each protein: SANC00531 was selected against P. falciparum M1 alanyl aminopeptidase, SANC00469 against P. knowlesi, SANC00660 against P. vivax, SANC00144 against P. ovale and SANC00109 against P. malariae. It was found that Plamsodium M1 alanyl aminopeptidase can be used as a potential drug target as it showed selective binding against different inhibitor compounds. This result will be investigated in future work though molecular dynamic analysis to investigate the stability of protein-ligand complexes.
- Full Text:
- Date Issued: 2019
A sociological analysis of Rhodes University Students previously diagnosed with Attention Deficit/Hyperactivity Disorder (ADHD) and prescribed psychostimulant medications
- Authors: Brasher, Chelsea Marilyn
- Date: 2017
- Subjects: Stereotypes (Social psychology) , Mental illness -- Public opinion , Attention-deficit hyperactivity disorder , Attention-deficit hyperactivity disorder -- Treatment , Symbolic interactionism
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/7610 , vital:21278
- Description: Using the theoretical framework of symbolic interactionism, bringing into account the labelling theory, the stigmas attached upon mental health issues and the medicalization approach, this study sought to document and analyze the viewpoints that previously diagnosed Rhodes University students hold towards the ADHD label and the subsequent usage of psychostimulant medications. Seven respondents were involved in an in-depth interviewing process. Out of the seven respondents chosen, five of the respondents were diagnosed in their primary school years, whereas the other two respondents were diagnosed in their late teenage years or early adult years. These respondents were included to enlighten and support the narrative of the five respondents diagnosed in their youth. The findings varied, with some of the respondents feeling negatively affected by having the ADHD label attached to them, and others, positively affected by it. The findings were also diverse in terms of how the respondents experienced stimulant usage, with some believing that the benefits of usage outweigh the costs, and others, the opposite. At a general level, it was discovered that the respondents were not affected by the ADHD label in terms of their interactions with others in primary school. It was only as they got older did some become fearful of the stigma attached to the ADHD label, and that of medication.
- Full Text:
- Date Issued: 2017
- Authors: Brasher, Chelsea Marilyn
- Date: 2017
- Subjects: Stereotypes (Social psychology) , Mental illness -- Public opinion , Attention-deficit hyperactivity disorder , Attention-deficit hyperactivity disorder -- Treatment , Symbolic interactionism
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/7610 , vital:21278
- Description: Using the theoretical framework of symbolic interactionism, bringing into account the labelling theory, the stigmas attached upon mental health issues and the medicalization approach, this study sought to document and analyze the viewpoints that previously diagnosed Rhodes University students hold towards the ADHD label and the subsequent usage of psychostimulant medications. Seven respondents were involved in an in-depth interviewing process. Out of the seven respondents chosen, five of the respondents were diagnosed in their primary school years, whereas the other two respondents were diagnosed in their late teenage years or early adult years. These respondents were included to enlighten and support the narrative of the five respondents diagnosed in their youth. The findings varied, with some of the respondents feeling negatively affected by having the ADHD label attached to them, and others, positively affected by it. The findings were also diverse in terms of how the respondents experienced stimulant usage, with some believing that the benefits of usage outweigh the costs, and others, the opposite. At a general level, it was discovered that the respondents were not affected by the ADHD label in terms of their interactions with others in primary school. It was only as they got older did some become fearful of the stigma attached to the ADHD label, and that of medication.
- Full Text:
- Date Issued: 2017
Masculine performance and enactment in the Rhodes University Rowing Club
- Authors: Dlamini, Thobile Lungile
- Date: 2017
- Subjects: Masculinity in sports -- South Africa , College sports -- South Africa , Male college athletes -- Psychology -- South Africa -- Case studies , Masculinity , Sex role , Rhodes University. Rowing Club , Rhodes University -- Students -- Psychology
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/4315 , vital:20647
- Description: Drawing on the interactions between gender and power in the South African context, this study explores how masculinities are produced, reproduced and contested in one particular realm of social life, namely organised university sport. The study focuses on a rowing club at a historically white South African university (RURC). The narratives of ten male participants (aged between 19 and 23) who self-identified as heterosexual and were recruited from RURC, were utilised to make meaning of the process of identity construction of young males who participate in organised sport within the higher education sphere. The ethnographic aspect of the study, which spanned over three months, provided a window into the norms, values and rituals of the club and how these variously reinforce or interrupt the prevailing gender order. Employing Connell’s typology of masculinities as a lens, the study traces the lived construction of masculinity in the individual lives of the members of RURC as one sphere of university life in which masculinities are produced and contested. Within a wider culture that has been characterised as white, heteronormative and patriarchal, the study argues that although masculinities and masculine performances in the RURC are highly contested the practices of the club ultimately perpetuate an exclusionary, orthodox masculinity.
- Full Text:
- Date Issued: 2017
- Authors: Dlamini, Thobile Lungile
- Date: 2017
- Subjects: Masculinity in sports -- South Africa , College sports -- South Africa , Male college athletes -- Psychology -- South Africa -- Case studies , Masculinity , Sex role , Rhodes University. Rowing Club , Rhodes University -- Students -- Psychology
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/4315 , vital:20647
- Description: Drawing on the interactions between gender and power in the South African context, this study explores how masculinities are produced, reproduced and contested in one particular realm of social life, namely organised university sport. The study focuses on a rowing club at a historically white South African university (RURC). The narratives of ten male participants (aged between 19 and 23) who self-identified as heterosexual and were recruited from RURC, were utilised to make meaning of the process of identity construction of young males who participate in organised sport within the higher education sphere. The ethnographic aspect of the study, which spanned over three months, provided a window into the norms, values and rituals of the club and how these variously reinforce or interrupt the prevailing gender order. Employing Connell’s typology of masculinities as a lens, the study traces the lived construction of masculinity in the individual lives of the members of RURC as one sphere of university life in which masculinities are produced and contested. Within a wider culture that has been characterised as white, heteronormative and patriarchal, the study argues that although masculinities and masculine performances in the RURC are highly contested the practices of the club ultimately perpetuate an exclusionary, orthodox masculinity.
- Full Text:
- Date Issued: 2017
New spaces and old stories: the Luminance woman, black womanhood and the illusion of the “new” South Africa
- Alweendo, Ndapwa Magano Nelao
- Authors: Alweendo, Ndapwa Magano Nelao
- Date: 2017
- Subjects: Luminance stores (South Africa) , Dhlomo, Khanyi , Dlamini, Judy , Women, Black -- South Africa -- Social life and customes , Women, Black -- South Africa -- Social conditions , Clothing trade -- South Africa , Social classes -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/42619 , vital:25220
- Description: This study examines ideas of black womanhood in post-apartheid South Africa. The opening of the Luminance boutique in 2013, previously owned by South African businesswoman and media mogul Khanyi Dhlomo in Johannesburg’s ultra-exclusive Hyde Park Corner, has been articulated as representing a rupture in the public and private performance of black womanhood. Luminance has positioned itself as a provider of world-class style and beauty and has embraced a narrative of black women’s empowerment in the process. The study is based on narrative semistructured interviews conducted Johannesburg with black women who have shopped at the boutique and women who believe themselves as having a meaningful connection to the store. The literature on black women, both internationally and in South Africa, acknowledges that black women experience multiple and intersecting oppressions of race, class and gender, among others. Located within black feminist theory, the study argues that the Luminance woman does represent some rupture in the historic understanding of black womanhood in South Africa. This woman is an elite player in both the corporate world and the world of luxury consumption, and is certainly entering spaces to which black women have historically been denied access. However, this study argues that there is a danger in reducing this woman to an oversimplified character, allowing responses to her to ignore the complexities of her reality in favour of the simplicity of her story, and ignore the structural socioeconomic challenges that continue to shape the lives of all black women in postapartheid South Africa. In this regard, the Luminance woman, while on the surface appearing to be an empowering new iteration of womanhood that should inspire other black woman, contributes to the erasure of her particular marginal experiences, and the oppression of black women in general. The story of the Luminance women contributes to a narrative of individual hard work and determination that frames her as a respectable example of what the “new” South Africa has delivered for its citizens. This woman is a model example of a South African who has succeeded because she took advantage of the opportunities supposedly afforded to all in the post-1994 era. It is therefore argued that praise of the Luminance woman serves a dual purpose: to reinforce the myth of equal opportunity in South Africa, and to lessen the legitimacy of marginalised groups’ experiences of oppression, especially black women who continue to constitute the poor majority.
- Full Text:
- Date Issued: 2017
- Authors: Alweendo, Ndapwa Magano Nelao
- Date: 2017
- Subjects: Luminance stores (South Africa) , Dhlomo, Khanyi , Dlamini, Judy , Women, Black -- South Africa -- Social life and customes , Women, Black -- South Africa -- Social conditions , Clothing trade -- South Africa , Social classes -- South Africa
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/42619 , vital:25220
- Description: This study examines ideas of black womanhood in post-apartheid South Africa. The opening of the Luminance boutique in 2013, previously owned by South African businesswoman and media mogul Khanyi Dhlomo in Johannesburg’s ultra-exclusive Hyde Park Corner, has been articulated as representing a rupture in the public and private performance of black womanhood. Luminance has positioned itself as a provider of world-class style and beauty and has embraced a narrative of black women’s empowerment in the process. The study is based on narrative semistructured interviews conducted Johannesburg with black women who have shopped at the boutique and women who believe themselves as having a meaningful connection to the store. The literature on black women, both internationally and in South Africa, acknowledges that black women experience multiple and intersecting oppressions of race, class and gender, among others. Located within black feminist theory, the study argues that the Luminance woman does represent some rupture in the historic understanding of black womanhood in South Africa. This woman is an elite player in both the corporate world and the world of luxury consumption, and is certainly entering spaces to which black women have historically been denied access. However, this study argues that there is a danger in reducing this woman to an oversimplified character, allowing responses to her to ignore the complexities of her reality in favour of the simplicity of her story, and ignore the structural socioeconomic challenges that continue to shape the lives of all black women in postapartheid South Africa. In this regard, the Luminance woman, while on the surface appearing to be an empowering new iteration of womanhood that should inspire other black woman, contributes to the erasure of her particular marginal experiences, and the oppression of black women in general. The story of the Luminance women contributes to a narrative of individual hard work and determination that frames her as a respectable example of what the “new” South Africa has delivered for its citizens. This woman is a model example of a South African who has succeeded because she took advantage of the opportunities supposedly afforded to all in the post-1994 era. It is therefore argued that praise of the Luminance woman serves a dual purpose: to reinforce the myth of equal opportunity in South Africa, and to lessen the legitimacy of marginalised groups’ experiences of oppression, especially black women who continue to constitute the poor majority.
- Full Text:
- Date Issued: 2017
New Labour Bill attacks workers rights
- COSATU
- Authors: COSATU
- Date: June 1997
- Subjects: COSATU
- Language: English, Afrikaans
- Type: text
- Identifier: http://hdl.handle.net/10962/135293 , vital:37255
- Description: The new Labour Relations Bill is a fundamental attack on many of the rights that workers have won over the past ten years. Just a few years ago the bosses and the government were complaining that unions are going on too many illegal strikes. Now that unions are more and more going on legal strikes, they want to make it as difficult as possible for unions to strike legally.
- Full Text:
- Date Issued: June 1997
- Authors: COSATU
- Date: June 1997
- Subjects: COSATU
- Language: English, Afrikaans
- Type: text
- Identifier: http://hdl.handle.net/10962/135293 , vital:37255
- Description: The new Labour Relations Bill is a fundamental attack on many of the rights that workers have won over the past ten years. Just a few years ago the bosses and the government were complaining that unions are going on too many illegal strikes. Now that unions are more and more going on legal strikes, they want to make it as difficult as possible for unions to strike legally.
- Full Text:
- Date Issued: June 1997
The external dimension in the transformation of Afrikaner Nationalism
- Authors: Botha, André Pedro
- Date: 1995
- Subjects: Afrikaners -- Ethnic identity , Afrikaners -- Politics and government , Nationalism -- South Africa -- History , Economic sanctions -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2763 , http://hdl.handle.net/10962/d1002973 , Afrikaners -- Ethnic identity , Afrikaners -- Politics and government , Nationalism -- South Africa -- History , Economic sanctions -- South Africa
- Description: This work looks at Afrikaner Nationalism, and more closely the changes it has undergone in years since external pressure has been applied against it from as early as 1946. This has been accomplished by placing it against the background of the international context ego as in relation to India and the British Commonwealth. Following a discussion of the ideology of nationalism in general, the thesis examines the specific case of Afrikaner Nationalism, which it portrays as an example of ethnonationalism. This latter is distinguished by familial ties and other stereotypes. After outlining the changing characteristics of Afrikaner Nationalism over time by reference to pronounciations by its leaders and other prominent spokesmen, this process of change is analysed with particular regard to the role played by international and other external pressures upon Afrikaner Nationalism. By carefully describing the changing attitudes of elite groups within Afrikaner Nationalism, the thesis assesses the impact of external factors. Then it is reasonably stated in this work that Afrikaner elites have become less exclusive under external pressure. The writer of this study is of the opinion that, give the fact that the doors of the National Party were thrown open, Afrikaner Nationalism and its aforementioned ideological organ are no longer identical.
- Full Text:
- Date Issued: 1995
- Authors: Botha, André Pedro
- Date: 1995
- Subjects: Afrikaners -- Ethnic identity , Afrikaners -- Politics and government , Nationalism -- South Africa -- History , Economic sanctions -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2763 , http://hdl.handle.net/10962/d1002973 , Afrikaners -- Ethnic identity , Afrikaners -- Politics and government , Nationalism -- South Africa -- History , Economic sanctions -- South Africa
- Description: This work looks at Afrikaner Nationalism, and more closely the changes it has undergone in years since external pressure has been applied against it from as early as 1946. This has been accomplished by placing it against the background of the international context ego as in relation to India and the British Commonwealth. Following a discussion of the ideology of nationalism in general, the thesis examines the specific case of Afrikaner Nationalism, which it portrays as an example of ethnonationalism. This latter is distinguished by familial ties and other stereotypes. After outlining the changing characteristics of Afrikaner Nationalism over time by reference to pronounciations by its leaders and other prominent spokesmen, this process of change is analysed with particular regard to the role played by international and other external pressures upon Afrikaner Nationalism. By carefully describing the changing attitudes of elite groups within Afrikaner Nationalism, the thesis assesses the impact of external factors. Then it is reasonably stated in this work that Afrikaner elites have become less exclusive under external pressure. The writer of this study is of the opinion that, give the fact that the doors of the National Party were thrown open, Afrikaner Nationalism and its aforementioned ideological organ are no longer identical.
- Full Text:
- Date Issued: 1995
An investigation into the relationship between creativity and academic performance in school children
- Authors: Noble, Sybil
- Date: 1970
- Subjects: Creative ability , Academic achievement , Performance in children
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3221 , http://hdl.handle.net/10962/d1012964
- Description: The subject of creativity is of interest not only to the research worker and educationist but also, with its related mental health aspect, to the clinical psychologist. As the writer's interest is in clinical psychology the opportunity, which occurred in 1968, to undertake research on creativity, was welcomed. This opportunity arose out of a larger piece of research into the relationships between personality variables and mathematical ability in school children. This involved the administration of personality tests and tests of arithmetic and mathematical ability to all the English speaking school children in Grahamstown from Standard 2 to Standard 10. The writer assisted in this testing program and did the greater part of the marking, scoring and entering on computer sheets. Thus personality test scores for over 2,000 children from the age of 8 or 9 to 17 or 18, both boys and girls were available. It was found possible to extend the computer program to calculate a score for creativity based on a combination of Cattell's personality factors and it was decided to compare these creativity scores with actual school performance, as measured by internal school examinations, which with the cooperation and agreement of the Cape Education Department and local schools, the writer was able to obtain. Intro., p.1.
- Full Text:
- Date Issued: 1970
- Authors: Noble, Sybil
- Date: 1970
- Subjects: Creative ability , Academic achievement , Performance in children
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3221 , http://hdl.handle.net/10962/d1012964
- Description: The subject of creativity is of interest not only to the research worker and educationist but also, with its related mental health aspect, to the clinical psychologist. As the writer's interest is in clinical psychology the opportunity, which occurred in 1968, to undertake research on creativity, was welcomed. This opportunity arose out of a larger piece of research into the relationships between personality variables and mathematical ability in school children. This involved the administration of personality tests and tests of arithmetic and mathematical ability to all the English speaking school children in Grahamstown from Standard 2 to Standard 10. The writer assisted in this testing program and did the greater part of the marking, scoring and entering on computer sheets. Thus personality test scores for over 2,000 children from the age of 8 or 9 to 17 or 18, both boys and girls were available. It was found possible to extend the computer program to calculate a score for creativity based on a combination of Cattell's personality factors and it was decided to compare these creativity scores with actual school performance, as measured by internal school examinations, which with the cooperation and agreement of the Cape Education Department and local schools, the writer was able to obtain. Intro., p.1.
- Full Text:
- Date Issued: 1970
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