Quantification of pre-competitive sleep/wake behaviour in a sample of South African cyclists
- Authors: Steenekamp, Travis
- Date: 2018
- Subjects: Sleep deprivation , Cyclists Health and hygiene South Africa , Sleep Physiological aspects , Performance , Performance anxiety
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59015 , vital:27408
- Description: The quantification of athlete pre-competitive sleep behaviour is of interest owing to the possibility that sleep loss may have a negative effect on health and performance. The purpose of this study was to monitor and quantify the sleep/wake patterns of South African cyclists prior to competitive races. A total of 336 cyclists, male and female and of differing competition levels, cycling in either the 2015 Tsogo Sun Amashova or the 2016 Telkom 94.7 Cycle Challenge completed an altered version of the Competitive Sports and Sleep Questionnaire. The questionnaire asked cyclists to report on precompetitive sleep over the past year. A subset of 92 cyclists also recorded a Core Consensus Sleep Diary for the three nights leading up to the races. The questionnaire showed that 67% of the cyclists reported worsened sleep at least once prior to competition within the past 12 months. The sleep diary found that the cyclists’ average sleep duration the night before the races was 6h19min (±1h38min), which was significantly less than two and three nights prior to the races. Sleep quality was also shown to deteriorate significantly the night before the races. The contributing factors leading to worsened pre-competitive sleep were the time the cyclists had to wake-up as well as perceived increases in sleep latency and awakenings after sleep onset. Anxiety was found to be the major cause of sleep disturbances. While females were found to be significantly more likely to report having experienced poorer sleep before competition in the past year, the sleep diary showed no difference in sleep the night before the races between the sexes. Females were significantly more likely to report instances of unpleasant dreams and waking up during the night. Again, the sleep diary data did not corroborate these findings. Females were also found to report significantly more accounts of nervousness or thoughts about competition as being the cause of sleep problems. There was no difference in sleep loss the night before competition when comparing competition-level groups. The only significant difference was that recreational cyclists were more likely to report sleeping in foreign environments as a cause of sleep disturbances. Despite a large percentage of cyclists experiencing pre-competitive sleep loss, over half (55%) perceived sleep loss to have no impact on their performance. Analysis of pre-sleep behaviour also revealed that the cyclists engaged in several practices that may have a negative effect on subsequent sleep. The vast majority of the cyclists (61%) indicated having no specific strategy to help them sleep the night before competition. Fifteen percent of cyclists reporting using media devices to help them fall asleep, a practice that has been shown to disrupt sleep. In conclusion, most cyclists, regardless of sex and level of competition experience precompetitive sleep loss attributed largely to anxiety but with the perception that this loss in sleep does not negatively impact their performance.
- Full Text:
- Date Issued: 2018
Quantification of water resources uncertainties in two sub-basins of the Limpopo River basin
- Authors: Oosthuizen, Nadia
- Date: 2018
- Subjects: Hydrologic models -- Limpopo River Watershed , Water-supply -- Limpopo River Watershed , Water-supply -- Management , Sustainable development , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Reservoirs -- Limpopo River Watershed
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63267 , vital:28388
- Description: The demand for water is rapidly growing, placing more strain on access to the resources and subsequently its management. For sustainable management, there is a need to accurately quantify the available water resources. Unfortunately, the data required for such assessments are frequently far from sufficient in terms of availability and quality, especially in southern Africa. In the absence of historical observed data, models are generally used to describe the different hydrological processes and generate data and information that will inform management and policy decision making. Ideally, any hydrological model should be based on a sound conceptual understanding of the processes in the basin and be backed by quantitative information for the parameterization of the model. Such data is however, often inadequate in many sub-basins necessitating the incorporation of the uncertainty related to the estimation process. Model parameter estimation and input data are significant sources of uncertainty that should be quantified. Also, in southern Africa water use data are unreliable because available databases consist of licensed information and actual use is generally unknown. In this study, the water resources of two sub-basins of the Limpopo River basin – the Mogalakwena in South Africa and the Shashe shared between Botswana and Zimbabwe – are estimated. The study assessed how uncertainties in the Pitman model parameterisation and input water use data affect the estimation of surface water resources of the selected sub-basins. Farm reservoirs and irrigated areas data from various sources were collected and used to run the Pitman model. Results indicate that the total model output uncertainty is higher for the Shashe sub-basin which is more data scarce than the Mogalakwena sub-basin. The study illustrates the importance of including uncertainty in the water resources assessment process to provide baseline data for decision making in resource management and planning. The study reviews existing information sources associated with the quantification of water balance components and gives an update of water resources of the sub-basin. The flows generated by the model at the outlet of the basin were between 22.6 Mm3 and 24.7 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The total predictive uncertainty of the model increased to between 22.2 Mm3 and 25.0 Mm3 when anthropogenic water use data such as small farm and large reservoirs and irrigation were included. The flows generated for Shashe was between 11.7 Mm3 and 14.5 Mm3 per month when incorporating uncertainty to the main physical runoff generating parameters. The predictive uncertainty of the model changed to 11.7 Mm3 and 17.7 Mm3 after the water use uncertainty was added. However, it is expected that the uncertainty could be reduced by using higher resolution remote sensing imagery.
- Full Text:
- Date Issued: 2018
Reducing the brittleness of poly-furfuryl alcohol resin used in composites
- Authors: Pillay, Princeton
- Date: 2018
- Subjects: Textile chemistry , Textile chemicals
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34350 , vital:33339
- Description: The thermoset market is dominated with petroleum-based products. The rising concerns on depletion of non-renewable resources and climate change has motivated researches and industries to find green alternatives for petroleum based materials. The thermoset polymer poly-furfuryl alcohol (PFA) displays good chemical, viscoelastic and moisture stability properties and importantly is bio-based, however, the cured PFA resin is very brittle. The approach of incorporating different types of particulate fillers into the PFA matrix and reinforcing the PFA matrix with flax fabric was used to address the brittleness issue associated with PFA. In the first study, flax fabric was treated with a diammonium phosphate based flame-retardant to reduce the flammability. Compression moulding was used to produce PFA biocomposites and PFA laminates. The effect of the flame-retardant was investigated using Scanning electron microscope (SEM), x-ray diffraction (XRD), fourier transform infrared (FTIR), and cone calorimeter, flexural and tensile tests. The flame-retardant treatment significantly improved the flammability properties, however, decreased the flexural and tensile properties. In the second study, 10 different fillers were selected, these being; ZnO, Clay, montmorillonite (MMT), Rubber, Chitin, Starch, CaCO3, Chitosan, Lignin and TiO2. These fillers were incorporated into the PFA resin at 2% and 5% concentration and reinforced with untreated (UT) flax fabric and flame-retardant (FR) treated flax fabric. Flexural, tensile and izod impact tests were performed on the cured laminates. Thermogravimetric analysis (TGA), SEM and micro x-ray computed tomography scan (CT scan) analysis was performed on selected samples. The inclusion of MMT and Rubber significantly increased the strength and the stiffness of the PFA/UT-Flax laminate while Clay and ZnO reduced the brittleness of the PFA/UT-Flax laminate. FR laminates generally exhibited poor mechanical properties regardless of the type of filler. This was the result of FR damaging the flax fibres during the compression moulding process and hindered the interaction between the PFA matrix and flax fabric. TGA results showed that FR treatment increased the thermal stability of the PFA laminate. SEM and CT scan analysis illustrated the large amount of voids between fabric layers, especially for UT-Flax laminates. The fillers MMT, Rubber and ZnO had a positive effect on the mechanical properties of UT-Flax laminates and therefore were used in the third study. A Box Behnken design of experiment was developed in which the concentration of MMT, Rubber and ZnO was varied between 0 – 5%. Multiple linear regression was used to model the mechanical properties of the PFA/UT-Flax laminates based on a full quadratic model. An optimized filler combination was determined with Solver ®. The experimental results of the optimised PFA/UT-Flax laminate were compared to the values predicted with the statistical model.
- Full Text:
- Date Issued: 2018
Regional and community food systems for rural households :|bthe case of maize in Mqanduli, Eastern Cape Province, South Africa
- Authors: Qangule, Mondli
- Date: 2018
- Subjects: Sustainable agriculture -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Agricultural systems -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10232 , vital:35383
- Description: Smallholder farmers have been growing food in their communities, but some are still food insecure. Therefore, appropriate food systems are very important for smallholder farmers’ self-reliance as well as food and nutrition security. The study focuses only on community and regional maize food systems for rural households. The main aim of this study was to investigate the regional and community food systems for smallholder maize farmers in Mqanduli. The objectives of the study were to profile smallholder maize farmers, describing the existing maize food systems and patterns in Mqanduli and also to determine factors that influence farmers’ participation in local or regional markets. Availability or convenient sampling and random sampling techniques were used to collect primary data from smallholder maize farmers. Descriptive statistics was used to profile smallholder farmers, as well as, in describing the existing maize food systems at Mqanduli. The binary logistic regression model was used to analyse the variables that had influenced the smallholder famers’ participation in markets. Descriptive results revealed that, smallholder maize farmers in Mqanduli are characterised by high participation in both local and regional markets. Moreover, they utilized both community and regional food systems. Logistic regression results indicated that, out of 11 variables included in the analysis as factors influencing farmers’ participation, 6 of them (age, level of education, market information, distance, access to credit and extension visit) were found to be significant and 5 (gender, amount of land, transport availability etc) were not significant. However, access to credit and distance were found to be the most significant variables, showing a positive relationship to smallholder maize producer`s market participation. Therefore, it was recommended that, there must be more investment in research by government and policy makers when it comes to food systems especially in rural areas, to enhance smallholders’ livelihood. More access to credit is also needed by farmers in order to be able to market their produces.
- Full Text:
- Date Issued: 2018
Rose-scented geranium oil yield and composition as affected by leaf age, herbage drying and paclobutrazol
- Authors: Dyafta, Viwe
- Date: 2018
- Subjects: Essences and essential oils Rose geranium oil
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10747 , vital:35733
- Description: Essential oil of rose scented-geranium is highly versatile and this makes it a very important essential oil in aromatherapy, medicine and cosmetics as well as in flavouring of food and drinks for different industries. The value of the essential oil is directly related to the quality of the oil. Therefore, it is important that the geranium growers take good care of agricultural practices in the production of essential oils as it is a crucial step where oil quality and yield is either obtained or lost. Thus, growing conditions and harvesting time must be cautiously established and controlled including herbage drying to ensure optimum yields and high quality of rose-scented geranium oil. The geranium oil production industry in South Africa is still expanding and oil yield & quality variation is important. This study was undertaken to determine the effects of herbage drying and method, leaf age and paclobutrazol concentrations on oil yield and quality of rose-scented geranium. The responses of oil yield and quality to drying effect was conducted on plant materials which were harvested from the University of Fort Hare Research Farm and glasshouse in December 2014 and October 2015. To determine the effect of drying method on essential oil yield and composition of rose-scented geranium the harvested leaves were dried in direct sunlight (20-35℃) and in a shade conditions (25℃/room temperature). Essential oil was obtained by hydro-distillation using a Clevenger apparatus. The oil samples were analysed by gas chromatography (GC) at the Dohne Agricultural institute. The major components of the oil conducted under the shade method were Linalool (5.58 percent), Menthone (0.68 percent), Citronellol (36.14 percent), Geraniol (7.29 percent), CitronellylFormate (15.39 percent) and GeranylFormate (3.30 percent), whereas those that were sun dried comprised of Linalool (3.56percent), Menthone (0.76 percent), Citronellol (32.25 percent), Geraniol (6.49 percent), CitronellylFormate (14.84 percent) and GeranylFormate (3.15 percent). The analysis of variance showed that freshly dried herbage followed by shade drying is suitable for highest oil yield. In addition, changes in essential oil composition and oil yield with leaf age in rose-scented geranium (Pelargonium capitatum x P. radens cv. Rose) were investigated in a glasshouse of the University of Fort Hare, during January to April and April to August 2012. The plants were allowed to grow to about 12-leaf stage. From top to bottom, the leaves were put into five groups (each group comprising two successive leaves, Pairs 1, 2, 3, 4 and 5). Leaf growth (leaf fresh and dry mass), and essential oil yield and composition data were collected and compared. The results indicated that, leaf fresh and dry mass data were significantly lower in the top-most (youngest leaves) as compared with the rest of the leaf pairs harvested. Essential oil in the youngest leaves was colourless, but as the leaves advanced with age, the oil tended to have a blue-green colour. Oil content (on dry mass basis) from the top to bottom, for Leaf Pairs 1, 2, 3, 4, and 5 were about 7.0, 4.9, 3.2, 2.4, 1.9 percent, respectively. Oil yield showed a significant increase in the second youngest pair of leaves and progressively declined, resulting in a significant lower yield in the oldest leaves. Leaf Pairs 1, 2, 3, 4 and 5, contributed about 19.3, 22.0, 17.71, 12.03 and 8.5 percent of the total yield per branch, respectively. Citronellol:Geraniol ratio was significantly lower in the young leaves than in the old leaves. Linalool and Geranylformate concentrations were the highest in the youngest leaves, and the opposite was observed in isomenthone. Other essential oil components did respond to leaf age. In support of research by Góra et al. (2002), Motsa et al. (2006) and Southwell and Stiff (1989), the current results indicate that early leaf age affects essential oil yield and composition. Thus, shorter regrowth cycles would increase essential oil yield and quality of rose-scented geranium. The paclobutrazol experiment was conducted in a glasshouse at the University of Fort Hare, Alice. A randomized complete block design with four replications was applied. One month after cutting back of the plants, PBZ was applied at the rates of 0, 100, 200 and 300 mg/l on the regrowth and harvested at four months of age. Data, such as chlorophyll content, plant circumference, plant height, fresh and dry mass and oil composition, were determined. The results highlighted that with an increase in PBZ concentration, total herbage mass and plant height tended to decline (Esmaielpour et al., 2011). Thus, in most cases herbage fresh and dry weight of treated plants had lower weight than the control. Paclobutrazol significantly reduced canopy circumference. There was no significant difference (P< 0.05) in oil yield and composition. Furthermore, observations showed that plants receiving PBZ had a deep green colour although the chlorophyll data did not show a significant difference. These results clearly show that PBZ helps geranium plants with compact canopy, which would enable farmers to increase income by increasing planting density, reducing distillation cost of the herbage volume and mass without reducing oil yield per plant. The findings, add another dimension to practical use of this hormone for commercial cultivation.
- Full Text:
- Date Issued: 2018
Ruthenium (II) complexes of mixed bipyridyl and dithiolate/thiourea ligands :|bsynthesis, characterization, photophysical and electrochemical studies
- Authors: Nkombi, Pelokazi
- Date: 2018
- Subjects: Ruthenium Ruthenium compounds Ligands
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10134 , vital:35358
- Description: Energy is one of the most important factor to influence human lives. The increased in energy demand as well as the detrimental effects posed by emission of greenhouse gases due to continue use of fossil fuels for electricity generation has led to a renewed focus on energy production using renewable energy sources which are relatively cheap, clean and environmentally sustainable. Among the various renewable energy sources used so far, the Dye Synthesized Solar Cells (DSSCs), a form of photovoltaic device is reported for their better efficiencies despite their low cost of production and ability to work relatively under low light conditions. A recent report on the solar-to-electricity conversion efficiency of a typical DSSC sensitizer made from zinc based porphyrin dye coupled with sintered titanium(IV) oxide as semiconductor was 13 percent. In this study, 2,2-bipyridyl-4,4-dicarboxylic acid (bpydc) was used as mixed ligand and four dithiolate ligands; L1 = dipotassium ethoxycarbonyl-1-cyanoethylene-2,2-dithiolate, L2 = dipotassium bis(ethoxycarbonyl)ethane-2,2-dithiolate, L3 = dipotassium cyanodithio imidocarbonate and L4 = dipotassium 2,2-dicyanoethylene-2,2-dithiolate were synthesized while four alkyl thiourea ligands, L5 = 1,3-dimethyl thiourea, L6 = 1,3-diethyl thiourea, L7 = 1,3-diisopropyl thiourea and L8 = 1-methyl thiourea were purchased and used as supplied without further purification. These ligands were used to prepare eight ruthenium(II) complexes of mixed bipyridyl/dithiolate/thiourea. The compounds were characterised by elemental analysis and spectroscopic techniques, namely: Fourier transform infrared (FTIR), Nuclear Magnetic Resonance (NMR), ultraviolet-visible and photoluminescence (PL). Cyclic voltammetry (CV) and square wave voltammetry (SWV) were used for the electrochemical studies. Photoluminescence and UV-Vis spectroscopies were used for geometric and photophysical studies of the complexes respectively. FTIR spectra confirmed presence of functional groups in ligands and coordination of these ligands to ruthenium(II) ions to form complexes. The UV-Vis confirmed that the Ru(II) dithiolene complexes exhibited square planar geometries while the Ru(II) thiourea complexes gave octahedral geometries, this was deduced from the transitions assigned to the complexes. All the ruthenium(II) complexes synthesized showed photoluminescence properties that are suitable for light harvesting and application for dye-sensitized solar cells. Cyclic and square wave voltammetry show Ru(II) thiourea complexes have better redox properties when compared to Ru(II) dithiolate complexes which is ascribed to ligand strength field possibly due to contribution from the two bonded NCS groups.
- Full Text:
- Date Issued: 2018
Scaffold accidents relative to South African construction
- Authors: Rantsatsi, Ndaleni Phinias
- Date: 2018
- Subjects: Construction industry -- Accidents -- South Africa , Construction industry -- Safety measures -- South Africa Building -- Accidents Accidents -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/35114 , vital:33627
- Description: The aim of this research is to highlight the types, frequency and causes of accident experienced by the scaffold workers on construction sites. As a result, provide recommendations on how to prevent or reduce accidents of scaffolding contractors on construction sites A review of related literature was conducted, primarily to avoid repeating existing research, to generate new findings. The quantitative research approach was adopted, and a non-experimental research design was used for this research which prompted the use of questionnaires for scaffold site management and scaffold workers. The sampling included site scaffold management, supervisors, health and safety practitioners, scaffold labourers, scaffold fixers/erectors, scaffold team leaders/ charge hands and scaffold inspectors in the South African construction industry in all nine provinces. The research findings revealed that slips, trips and falls accidents, struck by accidents and caught in/between accidents were the common accidents affecting scaffold workers on construction sites. The results further revealed that unsafe acts and conditions were the main causes of scaffold accidents. The empirical findings also revealed that most scaffold accidents occur during dismantling, manual handling and erection of scaffolding. The respondents are mostly working in the Limpopo and Mpumalanga provinces of South Africa. The research is vitally important for construction industry, scaffold contractors, clients and South African Department of Labour. It is recommended that a national accident register system be developed where accidents are captured and analysed to prevent possible accidents relative to scaffold contractors.
- Full Text:
- Date Issued: 2018
Smallholder farmers' selection criteria of maize varieties in Eastern Cape Province (Implications for adoption of GM maize) : the case of Port St. Johns, Flagstaff and Mqanduli
- Authors: Ngcinela, Siphokazi
- Date: 2018
- Subjects: Genetically modified foods
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10178 , vital:35372
- Description: Different maize varieties are produced by smallholder farmers in Eastern Cape Province in different agro ecological zones. Government cropping programmes have been promoting the production of GM maize varieties by smallholder farmers to enhance food security. However, there is no evidence to show how smallholder farmers are selecting the maize varieties they want to produce. On the other hand, smallholder farmers are slowly adopting GM maize due to number of factors affecting them. The study adopted Cross sectional design to collect the data from smallholder farmers from the three study sites. The sample size was 704 respondents. A semi structured questionnaire was used to collect primary data from smallholder farmers in Mqanduli (Lowest rainfall), Flagstaff (moderate rainfall) Port St. Johns LM (highest rainfall), under OR Tambo DM. Multistage sampling was utilised. SPSS version 24 was used to analyse descriptive statistics and Multinomial logistic regression model. STATA version 13 was used to analyse Crag’s double hurdle model. The results showed that, farmers were producing GM maize (Ht and Bt), unimproved OPV (landrace) and improved OPV (Sahara). The majority of farmers were producing OPVs. The findings further showed that, the selection of GM maize varieties is positively related to maize threat stalk borer damage. The results indicated that, most of the respondents were not aware of the GM permit conditions thus, they failed to comply with the expected conditions. The following variables influenced the adoption and intensity of adoption of GM maize: gender, highest educational level, household size, employment status, access to land, access to market, access to credit, membership to farmers group, main source of income, farm size, and access to extension services. It was concluded that from the three study areas different maize varieties were produced. Adoption of GM maize was influenced by the number of factors. GM maize permit condition were not met by smallholder farmers. It was recommended that, research should be done on OPVs which are the most preferred varieties by smallholder farmers. Extension officers and those who are adopting GM maize should be educated and trained about GM maize permit conditions.
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- Date Issued: 2018
Spatial and temporal heterogeneity of plant flammability
- Authors: Calitz, Wynand
- Date: 2018
- Subjects: Forest plants , Forest ecology Plants -- Adaptation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23500 , vital:30572
- Description: Heterogeneity in the natural environment has led to plants adapting traits to fit a niche. Within natural systems, fire has been a major driver of vegetation across the globe. Flammability has been suggested by many to be a trait adapted to reoccurring fire events. Much of the literature on flammability is theoretical and little has been done to cement it as a functional trait. In this thesis, I explore flammability across a wide range of plant species from both fire-free and -driven communities and compare observed results to other functional traits to identify if any link may exist between fire and being flammable. I further focus on the impact moisture availability may have on flammability as fire regimes are often correlated to rainfall season. Lastly, I investigate how different vegetation types respond to seasonal climate in terms of flammability. As a functional trait, flammability does correlate with traits associated with fire-driven system (e.g. small leaves in dense twig matrix). However, fire associated traits were also observed in fire-free species (Forest, Thicket, and Nama-Karoo), and in some cases traits not associated to fire proved flammable (e.g. large leaves on trees). I find that at a regional scale, plant moisture only correlates to flammability when rainfall amounts are well above or below average (e.g. drought). I also identify that species have different responses to moisture fluctuations and that inherent or accidental responses may influence observed flammability (e.g. trichomes). Lastly, I note that some biomes indicate strong association to season or climate (Fynbos and Thicket), while others indicate plasticity towards weather with species having different responses (Grassland). The study is the first to present estimates of flammability across a large number of species sampled at different times of the year. Future research will have to approach flammability as a meta-analysis by experimenting on different scales, particularly temporal and spatial scales.
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- Date Issued: 2018
Spatial variation in modelled hydrodynamic characteristics associated with valley confinement in the Krom River wetland: implications for the initiation of erosional gullies
- Authors: Schlegel, Philippa Kirsten
- Date: 2018
- Subjects: Soil erosion South Africa Eastern Cape , Wetland management South Africa Kromme River (Eastern Cape) , Wetland conservation South Africa Kromme River (Eastern Cape)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58684 , vital:27356
- Description: Gully erosion is a significant and widespread feature of southern African wetlands, including the wetlands of the Krom River, Eastern Cape. Gully erosion in wetlands is consistently being viewed as a major contributing factor to wetland degradation and eventual collapse. Many gullies exist in the Krom River and Working for Wetlands has spent large sums of money to stabilise head-cuts with the expectation that further erosion would be halted and possibly avoided altogether. Observations in the Krom River wetlands have revealed that most gullies in the wetland are initiated where the width of the trunk valley has been reduced as a consequence of deposition by tributary alluvial fans that impinge on the trunk valley and reduce its width. The aim of this study was to examine variation in hydrodynamic characteristics for a range of discharges, as flow in the broad Kompanjiesdrif basin (~250 meters wide) is confined in a downstream direction to a width of less than 50 meters by a combination of a large impinging left bank tributary alluvial fan that coincides with a resistant bedrock lithology. The study was done by collecting topographical survey data using a Differential Global Positioning System in order to create a Digital Terrain Model with a suitable resolution. Flow was recorded using a Marsh-McBirney Model 2000 Flo-Mate as well as recording the flood extent for each flow condition; this was used in the calibration process of the model. Vegetation measurements were conducted in order to calculate a roughness value across the valley floor. A two-dimensional raster based flood inundation model, CAESAR-Lisflood and a one-dimensional hydraulic analysis model, HEC-RAS, were then used to simulate different parameters associated with variation in discharge, including flow velocity, water depth and stream power, thereby creating a better understanding of the hydraulic characteristics that may promote the formation of gullies in the wetland. Based on these hydraulic analyses it is evident that the effect of impinging alluvial fans on hydraulic characteristics such as flow velocity, water depth and stream power, may lead to the initiation of gullies within the Krom River wetland. This work improves understanding of the collapse of palmiet wetlands in steep-sided valleys within the Cape Fold Mountains of South Africa, and can aid in wetland management.
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- Date Issued: 2018
Strength and conditioning practices of high school rugby coaches: a South African context
- Authors: Robinson, Bradley Charles
- Date: 2018
- Subjects: Rugby football coaches South Africa , Rugby football Coaching , Rugby football Physiological aspects , Rugby football Training , High school students Social conditions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63459 , vital:28413
- Description: Although the sport of rugby union is well established, the strength and conditioning practices of high school level players are not well known. Therefore, the purpose of this study was to examine the current strength and conditioning practices that coaches implement at South African high school level rugby. A secondary purpose was to compare practices between different types of schooling systems available in South Africa. An online survey or in person interview (depending on the school), adapted from previous strength and conditioning questionnaires, was conducted with 43 responses; including 28 schools among the top 100 rugby schools in South Africa for 2016 and 15 no-fee paying public schools in the Eastern Cape Province of South Africa. Results indicated that the top 100 rugby schools implement conditioning practices similar to the best-known international practices compared to no-fee paying schools who lacked the knowledge and skills in various strength and conditioning principles. It was found that all no-fee paying school coaches had insufficient qualifications to administer the correct training techniques. Coaches at all schools lacked the appropriate knowledge on injury prevention and scientifically based training programmes. It was concluded that education and skills around the best strength and conditioning practices for school level coaches needs to be improved and particularly in less privileged schools. The main goal being to reduce the risk of injury and improve performance across all sectors of the rugby playing population within the country. This was deemed crucial to the transformation goals set out by the South African Rugby Union, which would benefit from player development in lower socioeconomic schools.
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- Date Issued: 2018
Subjective measurements of persistence of time series
- Authors: Poswayo, Sihle
- Date: 2018
- Subjects: Time-series analysis , Space and time Time -- Philosophy
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/34372 , vital:33361
- Description: In this paper we suggest the use of subjective judgements to measure persistence in time series by comparing pairs of graphs with different Hurst exponents. The group of respondents consisted of 40 volunteers who were asked to identify the more jagged out of two graphs presented to them (that is, less persistent). The respondents were approached as a group and requested to work independently in the completion of ques- tionnaires administered to them. The respondents were supervised by the researchers. The graphs were simulated using time series package of Mathematica R [26]. The re- sponses were processed using an algorithm based on the Thurstone-Mosteller model for paired comparisons [29]. The results of the analysis show that the human eye is capable of distinguishing graphs of time series with Hurst exponent difference as small as only 0.02.
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- Date Issued: 2018
Sulphur isotope study of pyrite from the Twangiza-Namoya Gold Belt, (South Kivu, DRC): a proxy of gold provenance
- Authors: Moloto, Thapelo Refiloe Patience
- Date: 2018
- Subjects: Isotope geology -- Congo (Democratic Republic) , Pyrites -- Congo (Democratic Republic) , Gold mines and mining -- Congo (Democratic Republic) , Sulfur -- Isotopes -- Congo (Democratic Republic) , Hydrothermal deposits -- Congo (Democratic Republic) , Twangiza-Namoya Gold Belt, (South Kivu, DRC)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60552 , vital:27793
- Description: Gold in the highly prospective Twangiza-Namoya Gold Belt (TNGB) in the eastern Democratic Republic of Congo (DRC), with its four main deposits at Twangiza, Kamituga, Lugushwa and Namoya, appears to be correlated with the presence of sulphide minerals. Sulphur isotopic compositions of pyrite in the metasedimentary host rocks and in hydrothermal veins are used to identify the possible primary sources of hydrothermal sulphur and, by proxy, hydrothermal gold. The sulphur isotope signatures of the pyrites from the TNGB deposits show an overall range from -18.4%o to +22.6%o. S34 values in host rock pyrite are: -2.2%o to +3.0%o (Twangiza deposit), -4.2%o to -0.6% (Kamituga deposit), -18.4% to -12.7% (Lugushwa deposit), and +12.4% to +22.6% (Namoya deposit). The sulphur isotopic signature of vein pyrite is -5.2% to +3.0% (Twangiza deposit), -9.1% to -7.4% (Kamituga deposit), -0.3% to +3.2% (Lugushwa deposit) and +1.3% to +20.4% (Namoya deposit). The isotopic data indicate a primary sedimentary to evaporitic source of sulphur in the host rock pyrite. Pyrite from metadiorites shows magmatic S isotope compositions. Native gold was found in both sedimentary host rock and vein samples. This indicates that native gold was present in the primary metasedimentary sequence of the TNGB. Some vein pyrites in the TNGB have isotopic signatures that are similar to that of the host rock pyrite. These veins have formed from fluids extracted from the hosting metasedimentary sequence. Conversely, other vein pyrite shows different S34S values compared to the host rock pyrite, suggesting a fluid source that is different from the sedimentary source. Possibly, particularly in the Lugushwa deposit, an igneous source may have released sulphur and possibly gold bearing fluids in addition to those extracted from the sedimentary sequences in the TNGB. However, there is abundant evidence for sulphur and gold mobilised in the sedimentary host rocks and precipitated in the hydrothermal system of the TNGB.
- Full Text:
- Date Issued: 2018
Synthesis and application of novel coumarin-triazole-based polymeric sensors towards metal ion sensing
- Authors: Battison, Aidan Leigh
- Date: 2018
- Subjects: Polymers -- Optical properties , Polymers -- Electric properties Biosensors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23636 , vital:30591
- Description: One of the greatest challenges in the South African society is the pollutants which we are exposed to within our environment. The mismanagement and release of toxic analytes via different chemical, agricultural and industrial processes has led to a critical need for advanced monitoring systems for environmental protection, remediation and restoration. Industrial processes release a plethora of different pollutants into the earth, atmosphere, and aquatic ecosystems. Most pollutant causing activities are due to mining, agriculture, industry and chemical storage. Most contaminants released by these processes are not biodegradable and may be able to exude into water systems where they present an immense threat to environmental and human health. The number of different analytes released into the environment is greater than the number of sensors able to detect these species. Clearly, there is a need for a rapid and low-cost means of detection, recognition, and monitoring of these analytes. Fluorescent coumarin-triazole-based polymeric materials were designed and investigated as potential sensors for these metal ionic species. The Cu(I)-catalyzed 1,3-dipolar cycloaddition of azides and alkynes was the focus method of polymerization to form the fluorescence enhancing triazole moiety. The coumarin-triazole units formed the backbone of these polymeric material. The photophysical properties of the starting monomers and polymers were investigated in THF solvent. The polymers showed to have higher absorption and emission intensities than their respective starting monomers. The chemosensing capabilities of the polymers for metal ions were investigated through their emission properties. The polymers showed to have the greatest response towards Hg2+ and Ag+. Furthermore, the polymers displayed a reversible response towards Hg2+ in the presence of EDTA. The most responsive and reversible polymer system was applied for metal sensing capabilities towards Hg2+ from a known water source. This polymer proved to be a sensitive and reversible chemosensor for Hg2+ ions. The site of metal complexation on the polymer systems was verified by 1H NMR and FT-IR spectroscopy and was found to be mainly the triazole moieties from the polymer backbone. Finally, the possible mechanism for the fluorescent response of Hg2+ and Ag+ was also investigated.
- Full Text:
- Date Issued: 2018
Synthesis of folate-conjugated palladium nanoparticles
- Authors: Xolo, Luthando
- Date: 2018
- Subjects: Nanotechnology , Nanostructured materials Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36442 , vital:33943
- Description: In this study, the synthesis of two new folate-conjugated palladium (Pd) nanoparticles was carried out. This was done via two steps; firstly, the synthesis of palladium nanoparticles (PdNPs) capped with 4-aminothiophenol (4-Atp) and secondly, they were conjugated to the folate to form Folate-4Atp-PdNPs. All the above were characterized by using Fourier Transform Infrared spectroscopy (FTIR) which confirmed the formation of the targeted product (PdNPs-4-Atp-folate) as well as the 2-Aet linked with folate product (2-Aet-folate). The optical properties of the products formed were characterized further by using UV-Vis spectroscopy and Photoluminescence (PL). The size and shape of the nanoparticles were obtained by Transmission Electron Microscopy (TEM). The FTIR confirmed the formation of desired nanoparticles (Fa-4Atp-PdNPs), with peak of C=O stretching vibration at 1659 cm-1. The UV-Vis showed absorption peaks at 236 nm and 285 nm which was due to n-π* and π-π* transitions. The nanoparticles also showed excitation and emission peaks at 360 nm and 455 nm from the PL when excitation wavelength was set at 270 nm. The methanol soluble nanoparticles had an average size of 36 nm while the water-soluble nanoparticles were 4 nm in size. The HRTEM also showed the methanol nanoparticles were amorphous while the water-soluble nanoparticles were crystalline. The work reports on comparison of the methanol-soluble and water-soluble nanoparticles size distribution and the effect of capping agent used on the nanoparticles.
- Full Text:
- Date Issued: 2018
Synthesis, characterization and in vitro antiplasmodial evaluation of 4-& 8-aminoquinoline based-hybrid compounds
- Authors: Nqoro, Xhamla
- Date: 2018
- Subjects: Plasmodium falciparum
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/14649 , vital:40026
- Description: Malaria is a deadly disease and its drug resistance has been reported to be a challenge globally. The death toll caused by malaria has increased rapidly in different regions of the world. Quinoline scaffold molecules are combined with other classes of antimalarials to tackle drug resistance. The combination of quinoline scaffolds with other antimalarial compounds and metals-based drugs have been reported to be a potential approach to overcome drug resistance common in the currently used antimalarials. 4-Aminoquinoline was hybridized with selected organic molecules and metal-based compounds to form a class of hybrid compounds containing either an amide bond or ester bond as a linker between the parent molecules. 4-Aminoquinoline derivatives are known compounds and they were prepared via known synthetic routes and characterized. The hybrid compounds were characterized and the FTIR results confirmed the successful linkage of 4-aminoquinoline derivatives to selected organic scaffolds to form hybrid compounds. NMR results confirmed the successful formation of hybrid compounds. MS showed signals of the hybrid molecules confirming the successful isolation of the hybrid compounds. In vitro antiplasmodial assay was performed against asexual parasite and chloroquine was used as a reference drug. The percentage inhibition effects of the hybrid compounds were in a range of 96-102% at 5 µM and 36-96% at 1 µM suggesting that the percentage inhibition effect of the hybrid compounds was influenced by the drug concentration. Hybridization of either 4-aminosalicylic scaffold or ferrocene butanoic acid with 4- aminoquinoline derivatives is a potential synthetic route that can result in potent antimalarials. However, more research is needed to fully understand the structure-activity relationship of these hybrid compounds.
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- Date Issued: 2018
Synthesis, characterization and photophysical studies of RU(II)bipyridyl-dithiocarbamate complexes as sensitizers for dye sensitized solar cells
- Authors: Fudo, Zintle
- Date: 2018
- Subjects: Dye-sensitized solar cells Renewable energy sources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/6168 , vital:29498
- Description: The depletion of fossil fuels and the increasing energy demand for energy has led to the search for better and improved technologies with special focus renewable energy, especially solar cells. The first generation solar cells based on silicon are expensive, hence dye sensitized solar cells come in as a better alternative as these solar cells are environmental friendly, they have moderately good conversion efficiency and they are relatively cheap to produce. Dithiocarbamate ligands have been widely used in many research fields, as these are versatile ligands. Coordination of dithiocarbamates with metals such as ruthenium has produced high conversion efficiency and have the ability to extend the MLCT absorptions, and this can further extend their wavelength. In this study five dithiocarbamate sodium salt ligands were prepared and were coded as FL1= Aniline, FL2= p- toluidine, FL3= p- anisidine, FL4=dibenzyl, FL5=diphenyl. These ligands were used to synthesize Ru(II) metal complexes which were formulated as [Ru(FLx)(dcbpy)(NCS)] and [Ru(FLx)2(dcbpy)] where FLx is the dithiocarbamate ligand and dcbpy is 2,2-bipyridine-4,4’-dicarboxylic acid and the complexes were coded as FCx. The synthesized compounds were characterized using techniques such as the melting point, molar conductivity, FT-IR and NMR spectroscopy. For spectroelectrochemical studies of the metal complexes, techniques such as UV-Vis and photoluminescence spectroscopy were carried out. Furthermore, redox properties of the complexes were analyzed using cyclic and square wave voltammetry. The FT-IR displayed all the expected peaks of interest both in the dithiocarbamate ligands and in the metal complexes. The electronic spectra confirmed the successful coordination of ligand to the metal centre, the electronic spectra of the complexes also confirmed the six coordinate octahedral geometry of the complexes. The complexes exhibited some photoluminescence properties that are suitable for dye sensitization. The cyclic voltammogram of the complexes displayed more reduction potentials that could be attributed to the π-conjugation in the ligands incorporated during synthesis. The square wave voltammogram of the complexes is in agreement with the results obtained in cyclic voltammetry.
- Full Text:
- Date Issued: 2018
Testing the application of coastal altimetry in two South-Eastern African bights: the relationship between mesoscale features and chlorophyll-a, cyclonic eddies in the Indian Ocean
- Authors: Ziegler, Lisa
- Date: 2018
- Subjects: Oceanography -- Remote sensing -- Indian Ocean
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/15225 , vital:28188
- Description: Enhanced coastal altimetry, adaptive Leading-Edge Subwaveform(ALES), was used to study wo well known eddies along the southeastern African coast, namely the Delagoa Bight Lee Eddy and the Durban Lee Eddy. I address a two part problem. Firstly, how well does the application of coastal altimetry techniques behave in the coastal region? Secondly, is there a relationship between the eddies’ presence and chlorophyll-a (chl-a). Sea level anomalies (SLA) were computed from the re-tracked ALES data of two satellite missions — Envisat (used for Delagoa Bight eddy) and Jason -2 (for the Durban eddy) with geophysical corrections removed. These datasets were compared with the original satellite, 1 Hz RADS, AND AVISO gridded data. Two regions were selected to see if there was a biophysical link. A centre region of the eddy and an outside region of the eddy were taken. Results indicate that coastal altimetrywas successful in delimiting both features. ALES was less noisey and able to recover more data that were missed by the 1 Hz RADS dataset. Hovmöller plots showed the Delagoa Bight eddy to be more of a transient feature than semi-permanent, as had previously been suggested. Results from the linear model indicate a negative correlation between SLA and chl-a. This influence could be through facilitation of chl-a in the bight or just retaining chla. This is hard to elucidate without in situ data. These results show a promising indication that coastal altimetry will be a useful and reliable product to further biophysical coupling research along the coast.
- Full Text:
- Date Issued: 2018
The association of the bushclumps of Calcrete Bontveld with adjacent thicket
- Authors: Carvalho, Shandon Luke
- Date: 2018
- Subjects: Plant ecology -- South Africa -- Eastern Cape , Biodiversity conservation Landscape ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21949 , vital:29806
- Description: The thicket mosaic vegetation type known as Calcrete Bontveld is now only found at three sites within the Eastern Cape Province. Consisting of thicket-like bushclumps scattered among grassy dwarf shrubland, this vegetation is isolated from other systems due to its unique geographical location and the surrounding Valley Thicket. A strong similarity between the bushclumps of Calcrete Bontveld and the adjacent Valley Thicket has led to the aim of this study, which was to demonstrate that an association exists between these two vegetation types. To investigate this, two sites, namely Grassridge (natural vegetation on a mine) and Shamwari (natural due to its status as a reserve), were selected. This provided a unique comparison of the functionality of the two vegetation types and identified key processes responsible for the existence of this association. In terms of edaphic variables, soil organic content and field capacity, values were similar between bushclumps and thicket while soil depth was the greatest in thicket at both sites. At both sites, life forms, diversity and similarity indices were similar for bushclumps and thicket. By utilizing the Island Biogeography Theory, these bushclumps show an island-type origin and the distance between them and the adjacent Valley Thicket (mainland-type), as well as their size, influenced the association between the two vegetation types. Commonality of species between thicket and bushclumps are postulated to be tied to their dispersal mechanisms and fruit types. Bushclump isolation on flat-topped ridges excluded thicket species dispersed by autochory and anemochory. Zoochorous dispersal (by birds and mammals) was the common factor in the transfer of species between thicket and bushclumps as the latter is a large resource patch for fauna. The size of the bushclumps and their distance from the thicket influenced zoochorous dispersal. Larger and closer bushclumps attracted more birds and mammals than the small or more distant ones. These effects differ at the two sites due to the complex animal interaction that occurs in the Shamwari Game Reserve as opposed to the reduced animal interaction at Grassridge. This study suggests that an association exists between the bushclumps of Calcrete Bontveld and the adjacent Valley Thicket, and is reliant on the natural zoochory that occurs at each site.
- Full Text:
- Date Issued: 2018
The contribution of small-scale fisheries to rural livelihoods and food security : evidence from Hamburg, Eastern Cape Province, South Africa
- Authors: Budaza, Nwabisa
- Date: 2018
- Subjects: Small-scale fisheries -- South Africa -- Eastern Cape Food supply -- South Africa -- Eastern Cape Fishery management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10338 , vital:35396
- Description: Small-scale fisheries are known to provide food and income to millions of people around the world, but their role and existence is often ignored in development planning. The growing human demand for animal protein has become one of the foremost world challenges for which aquatic organisms have a significant role to play. In South Africa, small-scale fisheries have been recognized since the end of Apartheid, but the extent of the contribution of the sector to rural livelihoods and food security is not well understood. Using data drawn from a sample of 80 fishers in the coastal community of Hamburg, Eastern Cape, this dissertation presents an assessment of the contribution of small-scale fisheries to rural livelihoods, income and food security. The primary data were collected from the fishers using a structured questionnaire and non-probability sampling. The data were analysed with the assistance of descriptive techniques and a few simply statistical tests. The results of the study indicate that fishers in Hamburg catch a wide range of fish, which include wild kob, octopus, spotted grunter, white/black mussel cracker and white steenbras. Fishers in the study area are not solely dependent on small-scale fisheries for their livelihoods, income and food security, but generally supplement their welfare payments with fishing in order to sustain their livelihoods. About 78percent of the surveyed fishers depend on government grants, including old age grants, child support grants and social care grant. In terms of employment, 15percent of the surveyed fishers are casually employed, while 6percent are formally employed on a contract basis. Although they are not only dependent on fishing, nevertheless fishing is an important source of livelihood, income and food security. About 37percent of the fishers harvest marine resources for home consumption, while 7percent harvest solely for income, and 56percent harvest for both home consumption and income. Income generated from fisheries is approximately R935 per month and is used to buy food, electricity, fishing equipment and other household needs. The findings from this research underline the need for interventions such as coordinated institutions, improved infrastructure, improved monitoring and enforcement systems, as well as improved access to permit/fishing rights for sustainable use of marine resources.
- Full Text:
- Date Issued: 2018