An investigation of the movement of sediment through the Noordhoek headland bypass dunefield system at Cape Recife, South Africa
- Authors: Goosen, Gerrit Pieter
- Date: 2018
- Subjects: Sedimentation and deposition , Fluvial geomorphology Geomorphology Sand dunes -- Environmental aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22101 , vital:29840
- Description: A detailed study of the movement of sediment across the Cape Recife headland via the Noordhoek headland bypass dunefield was conducted. The Noordhoek HBD is important because of the environmental impacts anticipated on the sewerage works, settling ponds, and road to the Cape Recife lighthouse situated in the migration path of the dunefield to the ENE of its active boundary. The primary objective of the study was to investigate the movement of sediment in and through the Noordhoek HBD system. This study has provided sand transportation and dune migration rates by making use of various dune monitoring techniques. In doing so, useful predictions have been made as to when the settling ponds and the road to the lighthouse will be inundated. An indication has also been given as to how much sand moves through the system. Some key findings from this research included: the net migration direction of the Noordhoek HBD was found to be towards the east-north-east; the wind environment at the study area was classified as a high energy wind environment; this study has highlighted that various climatic factors such as rainfall and temperature influence the movement of sediment through dune systems; sediment transport was found to be directly related to the source area and topography; the central zone of the dunefield proved to be a groundwater recharge zone for the western and eastern zones; and the leading lobes of the migrating Noordhoek dunefield are gradually covering stabilising vegetation by pulses of dunes moving through. In this study, it was calculated that presently a total volume of about 26 000 m3 of sand is migrating into the vegetation at the leading lobes annually. If the Noordhoek HBD is left to run its natural course and migrate across the Cape Recife headland to the downwind beach, an approximate volume of 26 000 m3 of sand could be supplied to the downwind beach by this system. In doing so, it has the potential to play a role in replenishing some of the sand to Port Elizabeth’s eroded southern beaches via a natural process.
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- Date Issued: 2018
Application of hidden Markov models and their extensions to animal movement data
- Authors: Van Niekerk, Bracken
- Date: 2018
- Subjects: Markov processes Animal locomotion Time-series analysis
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/23835 , vital:30624
- Description: Hidden Markov Models (HMMs) have become increasingly popular in animal movement studies as they provide a flexible modelling approach and take the correlation between successive observations into account. They can segment the movement paths into latent states, which can be considered as rough proxies for the behaviours of the animals. This study comprises of two sections, both involving the application of HMMs to large terrestrial mammal movement data. Usually step lengths representing the displacement distances between successive observations, turning angles measuring the tortuosity, or a bivariate input of both variables are used as inputs in the models. It has been found in the literature that the turning angle is either included in the modelling process or it is excluded without much justification for doing so. The first part of this study investigates the nfluence of the turning angle on the model output and resultant interpretations of the HMMs when modelling the trajectories of large terrestrial mammals in southern Africa. Results revealed at different time scales, and for both predator and herbivore species in this study, that the turning angle does not influence the state allocation of the HMMs, which is the main output in terms of interpreting the behaviours of the animals. It is thought in most cases that the inclusion of the turning angle overcomplicates the models unnecessarily without contributing any additional information in terms of the behavioural interpretations or improving the overall fit of the models. This was found for the variety of movements of the species under observation in this study. The second part of this study attempts to validate the state allocation of the HMMs fitted to eland trajectories in the Greater Addo Elephant National Park in the Eastern Cape, with the use of camera trap data. This presented a unique opportunity as this type of data is mainly used for abundance or capture-recapture studies, and the HMMs are rarely validated as the true behaviours of the animals are seldom known. Results revealed that the same diel patterns were detected by the HMMs that were shown by the classified camera trap data. Direct comparisons of the observations where the dates and times matched for the telemetry and camera trap data could be done in several rare instances, which revealed many similarities. Although it was not an ideal comparison, the camera trap data provided a rough validation of the state allocation of the HMMs used in the study.
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- Date Issued: 2018
Aquatic habitat shift assessment in a groundwater-fed semi-arid stream: an investigation into the response of Karoo hydroecology to system variability
- Authors: Ellis, Natalie
- Date: 2018
- Subjects: Aquatic habitats -- South Africa -- Karoo , Arid regions -- South Africa -- Karoo , Biotic communities -- South Africa -- Karoo , Stream ecology -- South Africa -- Karoo
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61882 , vital:28072
- Description: From introduction: The subject of biological response to changes in aquatic habitat is one which has been well explored in many regions of the world. Examples include work in south east Spain by Mellado Diaz et al. (2008) and Oliva-Paterna et al. (2003), in western United States of America by Hauer and Lorang (2004), and in West Germany by Meyer et al. (2003). Similarly, a number of studies have been conducted in semi-arid regions, exploring elements such as erosion, climate, lithology and landscape formations (e.g. Boardman et al., 2013; Le Maitre et al., 2007; Meyer et al., 2003). However, apart from the study by Uys (1997), and Uys and O’Keeffe (1997), there is a noticeable lack of literature on aquatic habitat shifts in semi-arid stream systems, despite these systems being recognised for their high natural variability. This study provides a base-level approach to conducting habitat shift assessments in a semi-arid stream system and monitoring the hydroecological responses to system variability.
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- Date Issued: 2018
Assessing growth response patterns of microalgae to varying environmental conditions using sediments from ephemeral wetlands
- Authors: Mazwane, Sixolile
- Date: 2018
- Subjects: Microalgae -- South Africa , Wetland conservation -- South Africa Landscape ecology -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/22398 , vital:29966
- Description: Ephemeral wetlands serve as habitats for different fauna and flora. Microalgae make up a bulk of primary production in newly inundated wetlands and have a big influence on the aquatic community structure. As ephemeral wetlands have cyclical drying and wetting phases, algal species found in these habitats have evolved adaptations (i.e. dormancy and cysts) to survive during dry periods and become productive upon inundation. Algae have been used as ecological indicators in many aquatic ecosystems including wetlands, particularly associated with water quality and with varying inundation states. Whilst temperature and water level have been shown to affect microalgal biomass independently, this study aims to assess the effects of these two factors simultaneously on microalgal biomass, species diversity and community changes. The aim of the study was to investigate microalgal dynamics using two ephemeral wetlands in the Nelson Mandela Bay Municipality. The growth response patterns of microalgal communities to varying temperatures and inundation levels through experiments using dry temporary wetland sediments was also assessed. Dry sediments were collected from two depression wetlands with different sediment characteristics (1592 and Elephant Wallow (EW)). The study consisted of replicated treatments with three different surface area: volume ratios (SA:V) (Low surface area: volume (LSAV), Medium (MSAV) and High (HSAV)), inundated with distilled water. The microcosms were placed inside a Conviron environmental growth chamber and illuminated at between 106 to 138 μmol.m-2s-1, with a 12:12 light-dark cycle at constant temperatures of 12 °C (mean winter) and 22 °C (mean summer). Physicochemical data were recorded, and biological samples were collected every 4 days over a 28-day inundation period. In the field, Electrical conductivity (EC) and pH showed a gradual increase over the inundation period. The systems were well oxygenated (6-10 mg L-1). Overall, phytoplankton biomass in the field was ~10 μg L-1 whereas benthic biomass (MPB) was significantly higher 10 – 300 mg L-1. Within the experiments, the phytoplankton biomass showed a pattern while MPB biomass increased gradually for both experiments. There were no significant (p>0.05) differences between the 1592 and EW phytoplankton biomass. However, the MPB biomass showed significant (p<0.05) differences between the two sediments (EW high, 1592 low) and the experiments, respectively. In the winter experiment, the 1592 sediment had high phytoplankton biomass compared to EW, the reverse was observed for the MPB biomass. In summer experiment, similar results were observed in terms of phytoplankton biomass. For the MPBs, 1592 had greater biomass for all treatments compared to EW. The phytoplankton community for both field samples and experiments was dominated by chlorophytes (>50 %), followed by cyanophytes and euglenophytes (with cryptophytes in summer experiment) for both field and experiments. The MPB community was dominated by bacillariophytes (55 %) and chlorophytes (25 %) in the 1592 sediments and this was also the case with EW sediments bacillariophytes (70 %), although cyanophytes (15 %) made up the remainder of the MPB community. The 1592 sediments supported higher diatom abundances under the HSAV compared to the same treatment from the EW wetland suggesting that possibly grain size or texture might be responsible. In contrast, sediments from EW under LSAV conditions showed higher diatom cell numbers possibly indicating that increased water depth has the propensity to support greater diatom assemblages compared with the same water level for sediments from 1592. The results indicate that microalgae community is influenced by sediment type more than it is by water level. From this study it was also established that microalgae were able to reemerge from their dormancy state upon inundation and that tank experiments were successful in simulating natural ephemeral wetland conditions. The findings from this study will add to the available baseline data on microalgal dynamics in the ephemeral wetlands in South Africa, especially in semi-arid areas. This information can be valuable in enhancing our understanding regarding the role of microalgae in ephemeral wetlands in order to conserve them.
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- Date Issued: 2018
Assessing the implementation and effects of the Fetsa Tlala Food Initiative Programme in achieving its vision of eradicating household level food insecurity in Lukhanji Local Municipality, Eastern Cape Province, South Africa
- Authors: Njara, L I
- Date: 2018
- Subjects: Poverty -- South Africa -- Eastern Cape Food security -- South Africa -- Eastern Cape Households -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10476 , vital:35484
- Description: Declining agrarian activities in significant parts of the country, even in the subsistence sector, has meant that access to food is increasingly a function of household cash income, hence low-income households experience inadequate access to food. Over 12 million people in South Africa are vulnerable to food insecurity. Since 2013, substantial efforts and large sums of money have been devoted to poverty reduction through government’s Fetsa Tlala Food Production Initiative. Fetsa Tlala was conceptualised as an integrated government framework that seeks to promote food and nutrition security and to address the structural causes of food insecurity, which continue to perpetuate inequality and social exclusion. The main objective of this study is to assess the implementation and effects of Fetsa Tlala. The specific objectives include: to measure the direct and indirect benefits of Fetsa Tlala; to assess the cost-effectiveness of the programme; to evaluate the model of the programme using a social systems approach; and to assess the implementation approach of Fetsa Tlala. A cross-sectional study was carried on a sample of 70 households and four Fetsa Tlala projects in the Eastern Cape. Households were selected using the simple random sampling procedure. Structured and semi-structured interviews using questionnaires were conducted. The research objectives were analysed using both qualitative and quantitative approaches. Among the quantitative approaches used was a micro simulation exercise, which was performed to help understand the cost-effectiveness of the programme. The results show that the business model of the programme is not built with sustainability in mind and the systems approach was ignored when designing the programme. Furthermore, the cost of the programme outweighs its benefits. This study recommends that the programme should take into account human development and build a needs-based approach going forward. Further recommendations are that the government should target relevant partners, and prioritise agricultural insurance, infrastructure and agro-processing.
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- Date Issued: 2018
Assessing the income derived from agricultural hawking in Buffalo City Metropolitan Municipality, Eastern Cape, South Africa
- Authors: Seteni, Vuyo
- Date: 2018
- Subjects: Street vendors -- South Africa -- Eastern Cape Street vendors -- South Africa -- Eastern Cape -- Economic conditions
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10167 , vital:35364
- Description: The hawking business has grown profusely in Buffalo City Metropolitan Municipality, to such an extent that street hawkers are found on every street corner of the Metro. The literature suggests that street hawking holds great potential for employment creation for the unskilled population who cannot find employment opportunities in the formal sector. In light of the proliferation of street hawking in BCMM, the study aimed at assessing the performance of agricultural hawkers in the municipality by means of looking at hawkers’ strategies, determining their sales and net income, and ascertaining their level of ‘job satisfaction’. The sample was selected from the population of hawkers in three major towns of BCMM, namely Mdantsane, East London and King William’s Town. A sum of 200 respondents were selected in the study through interval based probability sampling. The study made use of a cross tabulation of the hawkers’ income according to the three main towns. The results revealed that that agricultural hawking contributes to poverty alleviation in Buffalo City Metropolitan Municipality, as the majority of hawkers earn enough to live above the poverty line. A correlation matrix was used to ascertain the strength and direction of association between hawkers’ monthly income and selected independent variables. The study also used an ordered probit model to determine which specific variables affect hawkers’ monthly income generated from fruit and vegetable sales. The results from the model suggest that business training is significantly and positively related to increasing monthly income, as are age, years of experience, and membership of a hawkers’ association. The study recommends that Buffalo City Metropolitan Municipality build new markets and improve the infrastructure of existing markets, and also provide proper sanitation and clean water to avoid unhygienic situations in street hawkers’ markets.
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- Date Issued: 2018
Assessment of indigenous forest degradation and deforestation along the wild coast, near Port St John’s, Eastern Cape Province, South Africa
- Authors: Katende, Lukyamuzi Lucky Fulgentius
- Date: 2018
- Subjects: Deforestation -- South Africa -- Eastern Cape , Forest degradation -- South Africa -- Eastern Cape Forest management -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30649 , vital:31006
- Description: Indigenous forests along the Wild Coast of the Eastern Cape Province have experienced both degradation and deforestation over the past decades. In early 2000, steps were taken to rehabilitate some of the degraded areas. Nevertheless, there is no monitoring mechanism in place, so little is known about the extent of degradation and impact of the rehabilitation efforts. The present study assesses the extent to which deforestation and degradation of the indigenous forests have occurred, and evaluates rehabilitation efforts in the study area around Port Saint John’s. Forest degradation was defined as the decrease in forest cover density while deforestation was defined as an increase in the trend of light forests and/ or a decrease in dense forests. The details for this study were obtained from multi – temporal remotely sensed data for a period between 1982 and 2013 (31 years). Multi-temporal Landsat satellite imagery for 1982, 1986, 1989, 2002, 2009 and 2013 was acquired and analysed. On the basis of prior knowledge of the area, the supervised classification approach was used. The Maximum likelihood supervised classification technique was used to extract information from satellite data. The classified images were filtered using a majority filtering procedure to reduce noise. Google Earth (Astrium) ancillary images were used to refine the classification based on expert rules. The derived changes in the degraded and rehabilitated areas were further validated through field visits. The overall image classification accuracy generated from Landsat image data ranged from 80% to 90%. It was noted that the area of dense forest almost doubled between 1986 and 1989, coinciding with a 59% decrease in the light forest. Subsequently, dense forests increased by 14,820 ha while light forests decreased by 16,690 ha between 1989 and 2002. The subsequent reduction in light forest coverage is explained by the establishment of the Participatory Forest Management (PFMA) approach by Department of Water Affairs and Forestry (DWAF) which reversed the degradation trend. However, specific degradation hotspots were identified, particularly where new settlements have been established. The emergence of the non-vegetated area increased gradually from 7% in 1986 to 23.4% in 2013. Notably, dense forest was observed to have experienced higher rates of forest degradation and deforestation than the light forest. The highest number patches were 4 recorded between 2002 and 1998, followed by between 2010 and 2013 and lastly 1986. Based on spatial connectedness of patches, the year 1986 had the highest landscape connectedness of forest vegetation (CONAT = 35.3) followed by 2002 and 1996 while the year 2010 and 2013 had the lowest landscape contiguity. Over the study period, the distribution of patches clearly shows that forest degradation and deforestation rates were lower in the years 1986, 1998 and tremendously increased in the later period of between 2010 and 2013. However, as a result of rehabilitation efforts, dense forest was seen to steadily gain more land than light forest. Finer details of degradation trends could not be easily picked from the images used in the study, given their spatial resolution limitations. That notwithstanding, the trends identified are good for overview decisions. The study has also established that de-agraianisation, forest restoration and rehabilitation greatly contributed to increased forest cover. Therefore, with more use of GIS by forest managers, and imagery of the high resolution being readily available, forests will in future be easily monitored using remote sensing.
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- Date Issued: 2018
Assessment of pharmaceutical equivalence of topical cream products containing hydrocortisone acetate using in vitro release testing (IVRT)
- Authors: Mudyahoto, Nyengeterai Amanda
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63384 , vital:28404
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Assessment of pheromone specificity in Thaumatotibia leucotreta (Meyrick) populations with focus on pest monitoring and the regional rollout of the sterile insect technique in citrus
- Authors: Joubert, Francois D
- Date: 2018
- Subjects: Cryptophlebia leucotreta , Pheromone traps , Citrus -- Diseases and pests -- South Africa , Cryptophlebia leucotreta -- Contol , Cryptophlebia leucotreta -- Biological control
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60665 , vital:27812
- Description: False codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is considered the most important indigenous pest of citrus in southern Africa. It is recognized by several markets as a phytosanitary organism and the efficient control of this pest is now more important than ever. The pheromone communication between the male and female moths has been exploited in order to control FCM through the sterile insect technique (SIT). The sterilized males used for all SIT programmes across South Africa come from a colony that originates from wild material collected from the Citrusdal area of the Western Cape Province. The aim of this study was to determine if any differences in attractiveness of females to males exist between different geographical populations of FCM and if so what impact this would have on the male’s ability to locate females from other populations via the volatile sex pheromone released by the female. Laboratory trials with Y-tube olfactometers and flight tunnels tested the attraction of male moths to virgin females, but did not yield any consistent results. Field experiments were conducted with sterile male Citrusdal moths released and recaptured in yellow delta traps in two separate trials. For one trial, the traps were baited with live virgin females from five different geographical populations including Addo, Nelspruit, Marble Hall, Citrusdal and the Old colony, which is a mixture of several populations. For the other trial traps were baited with various synthetic pheromone blends including three regional blends which included South Africa, Ivory Coast and Malawi and three commercial blends including Pherolure, Isomate and Checkmate. For the virgin female trial the Citrusdal males showed a significant preference for females from their own population. There was also a significant difference in the recaptures from the different synthetic pheromones. The South African blend was the most attractive of all the regional and commercial blends. A cross-mating trial was also conducted under laboratory conditions in petri dishes with five different FCM populations including Citrusdal, Addo, Marble Hall, Nelspruit and Old (mixed origin). Females produced more eggs when mated with males from the same population for the Addo, Marble Hall, Nelspruit and Old (mixed origin) populations. The only case in which this was statistically significant was for the Marble Hall population. All the crosses produced viable eggs and the origin of the male or female did not influence egg hatch. The results from this study may lead to improvements in both the control and monitoring of FCM populations. The control methods include mating disruption, attract-and-kill and SIT. Tailoring these methods for a specific growing area with a pheromone blend originating from the area or releasing sterile moths from a colony that originates from the area may optimize the available monitoring and control options.
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- Date Issued: 2018
Assessment of the long-term response to rehabilitation of two wetlands in KwaZulu-Natal, South Africa
- Authors: Cowden, Craig
- Date: 2018
- Subjects: Wetlands -- South Africa -- KwaZulu-Natal Wetland restoration -- South Africa -- KwaZulu-Natal Wetland management -- South Africa -- KwaZulu-Natal Wetland conservation -- South Africa -- KwaZulu-Natal Wetland ecology -- South Africa -- KwaZulu-Natal Ecosystem management -- South Africa -- KwaZulu-Natal
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/60606 , vital:27802
- Description: Assessing the outputs and outcomes of wetland rehabilitation activities is recognised by the 'Working for Wetlands' programme in South Africa as important, but to date has been limited. An assessment of the ecological outcomes and the structural outputs of the Working for Wetlands rehabilitation implemented in the Killarney and Kruisfontein wetlands, KwaZulu-Natal, in 2005 was undertaken. The assessment of outcomes included an evaluation of the changes in terms of ecological integrity and the supply of ecosystem services, using WET-Health and WET- EcoServices assessment techniques respectively, and vegetation composition. Improvements in hydrological and geomorphic integrity were recorded in both wetlands, resulting in improved ecosystem services delivery. However, investigation of vegetation composition using the Wetland Index Value and Floristic Quality Assessment Index showed that, seven years after rehabilitation, KiNamey's vegetation composition had improved, but Kruisfontein's vegetation was still largely dominated by pioneer species and appeared to be stable, but in a severely transformed state. The response of these wetlands has shown that sites for rehabilitation should be screened before work begins, and wetlands requiring intensive management of vegetation recovery should be assessed in terms of the objectives and the anticipated benefits of the project. The assessment of the outputs included an evaluation of structural integrity, survival and cost- effectiveness. Limited issues, mostly relating to deviations from the designs during construction, were identified with regards to the structural outputs at each of the wetlands. However, the spreader canals at both Killarney and Kruisfontein wetlands were not functioning as intended and concentrated flows from the spreader canals were evident in both wetlands. The use of spreader canals should therefore be carefully planned and implemented for future wetland rehabilitation projects. Consideration of ZAR per hectare equivalent re-instated/secured provided a useful initial means of determining the cost-effectiveness of the wetland rehabilitation. However, additional factors need to be considered, such as, the nature of the rehabilitation activities, the type and size of the problem being addressed, rehabilitation of priority wetlands, limitations imposed by funders, and risks that need to be addressed by the rehabilitation strategy. Furthermore, the evaluation of the Killarney and Kruisfontein wetlands highlighted the need to revise the Water Research Commission's Wetland Management Series, especially those documents or guidelines relating to rehabilitation planning (WET-RehabPlan), interventions (WET-RehabMethods), and monitoring and evaluation (WET-RehabEvaluate).
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- Date Issued: 2018
Assessment of the microalgal community structure and biomass in surface waterbodies of the Eastern Cape Karoo region earmarked for shale gas exploration
- Authors: Roussouw, Natasha Kimberlee
- Date: 2018
- Subjects: Fresh water -- Eastern Cape , Water-supply -- South Africa -- Eastern Cape Water-supply, Rural -- South Africa -- Eastern Cape Constructed wetlands Watershed management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/35234 , vital:33655
- Description: The Eastern Cape Karoo region of South Africa typically displays low rainfall and high temperatures, which is particularly concerning considering the shale gas exploration/extraction project proposed recently. Almost 90% of the fracking fluid consists of water and with the Karoo region already classified as a water-stressed region, the increased demand for freshwater for fracking could put further pressure on water resources of the region. By understanding the ecological functioning of the lower trophic levels, likely implications for higher trophic levels can be determined, and ultimately, recommendations for mitigation actions can be made. Here, observations aimed at understanding the dynamics of lower trophic levels are presented, that is, the microalgal biomass and assemblage composition within three characteristic surface waterbodies of the region. In addition, the work focuses on the smaller, more dynamic temporary wetland systems typical of this water-scarce region, with the aim of understanding the significance of single species macrophyte cover in relation to the lower trophic levels. Thirty-three waterbodies were sampled (natural depressions = 13, dams = 9, rivers = 11) during November 2014 (austral spring) and April 2015 (austral autumn). Waterbody physico-chemistry, hydro-morphometry, habitat cover and surrounding land-use, as well as microalgal biomass and assemblage composition within each waterbody type were measured. Thirteen natural depression wetlands were sampled during October 2015, December 2015 and March 2016. Once again, waterbody physico-chemistry, microalgal biomass and assemblage composition were measured. However, in addition, Schoenoplectus decipiens macrophyte cover and microalgal (diatom) species composition were also determined. In general, no significant differences in microalgal biomass between the three main waterbody types of the Eastern Cape Karoo region were found; however, the different waterbody types each displayed distinct microalgal assemblage compositions. Also, Schoenoplectus decipiens cover had negligible effects on microalgal biomass and assemblages in the temporary wetlands investigated here. These results suggest that the generalist nature of species occupying these systems allows them to adapt to the ever-changing conditions typical of this region. Ongoing monitoring initiatives considering impending hydraulic fracturing activities should include a comprehensive species-level diversity census, which could further inform management of any impacts associated with this potential disturbance.
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- Date Issued: 2018
Bayesian hierarchical modelling with application in spatial epidemiology
- Authors: Southey, Richard Robert
- Date: 2018
- Subjects: Bayesian statistical decision theory , Spatial analysis (Statistics) , Medical mapping , Pericarditis , Mortality Statistics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59489 , vital:27617
- Description: Disease mapping and spatial statistics have become an important part of modern day statistics and have increased in popularity as the methods and techniques have evolved. The application of disease mapping is not only confined to the analysis of diseases as other applications of disease mapping can be found in Econometric and financial disciplines. This thesis will consider two data sets. These are the Georgia oral cancer 2004 data set and the South African acute pericarditis 2014 data set. The Georgia data set will be used to assess the hyperprior sensitivity of the precision for the uncorrelated heterogeneity and correlated heterogeneity components in a convolution model. The correlated heterogeneity will be modelled by a conditional autoregressive prior distribution and the uncorrelated heterogeneity will be modelled with a zero mean Gaussian prior distribution. The sensitivity analysis will be performed using three models with conjugate, Jeffreys' and a fixed parameter prior for the hyperprior distribution of the precision for the uncorrelated heterogeneity component. A simulation study will be done to compare four prior distributions which will be the conjugate, Jeffreys', probability matching and divergence priors. The three models will be fitted in WinBUGS® using a Bayesian approach. The results of the three models will be in the form of disease maps, figures and tables. The results show that the hyperprior of the precision for the uncorrelated heterogeneity and correlated heterogeneity components are sensitive to changes and will result in different results depending on the specification of the hyperprior distribution of the precision for the two components in the model. The South African data set will be used to examine whether there is a difference between the proper conditional autoregressive prior and intrinsic conditional autoregressive prior for the correlated heterogeneity component in a convolution model. Two models will be fitted in WinBUGS® for this comparison. Both the hyperpriors of the precision for the uncorrelated heterogeneity and correlated heterogeneity components will be modelled using a Jeffreys' prior distribution. The results show that there is no significant difference between the results of the model with a proper conditional autoregressive prior and intrinsic conditional autoregressive prior for the South African data, although there are a few disadvantages of using a proper conditional autoregressive prior for the correlated heterogeneity which will be stated in the conclusion.
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- Date Issued: 2018
Best simultaneous approximation in normed linear spaces
- Authors: Johnson, Solomon Nathan
- Date: 2018
- Subjects: Normed linear spaces , Approximation theory , Mathematical analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58985 , vital:27400
- Description: In this thesis we consider the problem of simultaneously approximating elements of a set B C X by a single element of a set K C X. This type of a problem arises when the element to be approximated is not known precisely but is known to belong to a set.Thus, best simultaneous approximation is a natural generalization of best approximation which has been studied extensively. The theory of best simultaneous approximation has been studied by many authors, see for example [4], [8], [25], [28], [26] and [12] to name but a few.
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- Date Issued: 2018
Biological activity of macrofungi in South Africa against respiratory and lung disease
- Authors: Didloff, Jenske
- Date: 2018
- Subjects: Macrofungi , Microbiology Medical microbiology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/30138 , vital:30835
- Description: Macrofungi represent an untapped source of natural bioactive compounds for various diseases, which have been targeted as potential therapeutic agents. The medicinal uses of macrofungi discovered to date include anticancer, antidiabetic, antioxidant, antimicrobial, and immunomodulatory properties. The knowledge regarding the medicinal uses of macrofungi in Africa is limited; however, it is believed that Africa may contain a large number of unidentified species of macrofungi. The objectives of this study were to: (i) screen the macrofungal extracts for antimicrobial activity against microorganisms responsible for respiratory diseases (e.g. Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae, Streptococcus pyogenes, Staphylococcus aureus, Mycobacterium tuberculosis, HIV-1), (ii) determine the effect of macrofungal extracts on bacterial morphology, (iii) investigate the cytotoxicity of macrofungal extracts against human lung carcinoma cells, and to elucidate the mechanism/s of action of cytotoxicity/anticancer activity. In vitro bioassays for antimicrobial activity included: ρ-iodonitrotetrazolium chloride assays and microplate alamar blue assay (MABA), while the HIV-1 reverse transcriptase colorimetric ELISA and HIV-1 protease fluorometric assay kits were used for anti-HIV activity. Cytotoxicity of the macrofungal species against A549 lung cancer cell line was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, and the IC50 values determined for the most cytotoxic macrofungal spp. The mechanism of cytotoxicity was investigated by cell cycle analysis and fluorescent staining to observe morphological and biochemical changes (i.e. acridine orange, caspase activation). Ethanol extracts of Amanita foetidissima, Gymnopilus junonius, Pisolithus tinctorius, Fomitopsis lilacinogilva, Stereum hirsutum and Pycnoporus sanguineus showed higher antimicrobial activity against the Gram-positive bacteria than aqueous extracts, with S. pneumoniae being the most susceptible. The ethanol extracts of Agaricus campestris, Chlorophyllum molybdites, Gymnopilus penetrans, Pseudophaeolus baudonii and Laetiporus sulphureus exhibited anti-TB (tuberculosis) activity with minimum inhibitory concentrations (MICs) ranging between 500-1,000 μg/mL. C. molybdites ethanol extract inhibited HIV-1 protease activity (IC50: 49.7 μg/mL). The macrofungal extracts did not inhibit HIV-1 reverse transcriptase activity. Ethanol extracts of F. lilacinogilva, G. junonius, P. sanguineus and the aqueous extract iv of P. baudonii were cytotoxic against A549 lung cancer cells at IC50 values of 69.2±3.6, 57±5, 7.4±1.1 and 53.6±1.1 μg/mL, respectively. Cell cycle arrest was observed in the G2 phase for both P. sanguineus and P. baudonii, and G2/M and early M phases for G. junonius and F. lilacinogilva, respectively. Apoptosis induced by macrofungal extracts was confirmed by fluorescent staining. Morphological and biochemical changes included chromatin condensation, membrane blebbing, loss of cytoskeletal structure, caspase activation and phosphatidylserine translocation. This study demonstrates the biological activities of selected macrofungal extracts and their potential mechanisms of action. Isolation and identification of active compounds require further analysis.
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- Date Issued: 2018
Biophysical monitoring of unphosphorylated STAT3 homodimerization
- Authors: Mtwebana, Sinethemba Siphokazi
- Date: 2018
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63957 , vital:28514
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
BODIPY dyes for singlet oxygen and optical limiting applications
- Authors: Harris, Jessica
- Date: 2018
- Subjects: Photosensitizing compounds , Active oxygen -- Physiological effect , Photochemotherapy , Cancer -- Treatment , Nonlinear optics , BODIPY (Boron-dipyrromethene)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58002 , vital:27014
- Description: A series of structurally related BODIPY dyes were synthesised and characterised. Their photophysical properties were studied in order to determine whether they would be suitable candidates for use as photosensitisers in the photodynamic therapy (PDT) treatment of cancer. The synthesis of two highly fluorescent BODIPY cores was achieved via the acid-catalysed condensation of a pyrrole and a functionalised aldehyde. In order to promote intersystem crossing, and hence improve the singlet oxygen generation of these dyes, bromine atoms were added at the 2,6-positions of the BODIPY core. These dibrominated analogues showed good singlet oxygen quantum yields, and excellent photostability in ethanol. In order to red-shift the main spectral bands of the BODIPY dyes towards the therapeutic window, vinyl/ styryl groups were introduced at the 3-, 5-, and 7-positions via a modified Knoevengal condensation reaction. The addition of vinyl/ styryl groups to the BODIPY core caused an increase in fluorescence quantum yield as well as a decrease in singlet oxygen quantum yield with respect to the dibrominated analogues. However, two of the red-shifted BODIPY dyes still showed moderate singlet oxygen quantum yields. The use of BODIPY dyes in nonlinear optics (NLO) was explored. The nonlinear optical characterisations and optical limiting properties of a series of 3,5-dithienylenevinylene BODIPY dyes were studied, both in dimethylformamide (DMF) solution and when embedded in poly(bisphenol A carbonate) (PBC) as thin films. The 3,5-dithienylenevinylene BODIPY dyes showed typical nonlinear absorption behaviour, with reverse saturable absorption (RSA) profiles, indicating that they have potential as optical limiters. The second-order hyperpolarizability (Y), and third-order nonlinear susceptibility (/m[/(3)]) values are also reported for these dyes. The optical limiting values of one of the BODIPY dyes in solution, and two of the BODIPY-embedded PBC films, were below the maximum threshold of 0.95 J-cm-2. The effect of addition of substituents on the electronic structure of the BODIPY dyes was investigated using TD-DFT calculations. The calculated trends closely followed those determined experimentally.
- Full Text:
- Date Issued: 2018
Calibration and validation of satellite data (images) over inland water bodies and the effect caused by the adjacency towards them
- Authors: Faniso, Zimbini
- Date: 2018
- Subjects: Hydrology Remote sensing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10353/10350 , vital:35400
- Description: Remote sensing of inland water quality is a particularly challenging satellite Earth observation (EO) application. This arises because inland water bodies are small and optically complex targets that are generally dark compared to surrounding land. Inland water bodies are source supplies of water for both living and non-living organisms, that include human beings hence they need an observation. The spatial distribution of water changes over time and that leads to issues in different sectors like agricultural sector, environmental services and ecological issues. Signal reaching the satellite is usually dominated by light scattered in the atmosphere. Aerosols are strongly variable atmospheric constituents and play a major role in generating this unwanted signal which must be quantified and removed before any conclusions about water state and condition. In order to see how the aerosols affected the water state the light scattered in the atmosphere will be observed through electromagnetic spectrum bands in the atmosphere. This study will analyse the visible and near infrared wavebands of the electromagnetic spectrum as well as where it will be easy to distinguish the atmospheric noise types. A field campaign has been executed at Roodeplaat dam near Pretoria relating to Calibration and Validation (CalVal) of the recently launched Sentinel 2 and Sentinel 3 satellites. In situ measurements were taken at Roodeplaat dam simultaneously with the satellite overpass. Atmospheric Radiative Transfer Modelling (RTM) is required to analyse the satellite surface measurement data that is in the form of radiant quantities. Aerosol models for radiative transfer have been evaluated and refined to improve retrieval accuracy of water-leaving radiance at Roodeplaat dam. A retrieval algorithm for water-leaving radiance (Lw) and remote-sensing reflectance has been developed to analyse the sensitivity of the retrieval to aerosol optical properties, sensitivities, as well as proposals for enhanced retrieval methods, are presented.
- Full Text:
- Date Issued: 2018
Capacitance spectroscopy of GaAs p-i-n solar cells embedded with GaNAs quantum wells
- Authors: Venter, Danielle Ahlers
- Date: 2018
- Subjects: Solar cells , Photocatalysis Nanotechnology Fuel cells
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/21593 , vital:29713
- Description: The search for higher efficiencies in solar cell technology has brought forth competitive ideas, among them tandem solar cells (TSC) and intermediate-band solar cells (IBSC). These cells deliver higher efficiencies by absorbing a wider range of the electro-magnetic spectrum compared to conventional cells, but do come with unique challenges. This includes, amongst others, the need to find suitable material systems, which can fully realise the requirements behind the concept. In this study, the notion of using dilute nitrides in III-V systems as a candidate for the IBSC is considered. Incorporation of GaNAs QW structures into GaAs p-i-n solar cells are structurally, optically and electrically characterised. At a first estimate the photovoltaic properties of the material is obtained through current-voltage (I-V) measurements under illumination. It is observed that the open circuit voltage (𝑉𝑂𝐶), short circuit current (𝐼𝑆𝐶) and conversion efficiency decrease upon the incorporation of the QWs. Electrically active defect levels are notorious for reducing the life time of electron-hole pairs, directly impacting cell efficiency. In an effort to gain a clearer understanding of this behavior, the study of electrically active deep level center present in such devices were investigated. A comprehensive understanding of defects in semiconductors remains of fundamental importance and thus reinforces this approach. This was done using two of the most commonly used semiconductor defect spectroscopy techniques viz. admittance spectroscopy (AS) and deep level transient spectroscopy (DLTS). Since in principle, these two techniques are similar, deep level related results were compared in order to verify the validity of the results. The devices under study, GaNAs/GaAs embedded QW p-i-n solar cells, were grown by molecular beam epitaxy (MBE). In particular, the doping of the quantum wells was varied and this effect on the electrical properties investigated. Four samples were studied and their electrical, optical and structural properties compared. The sample series consisted of a reference GaAs p-i-n diode that contained no embedded QWs and three GaAs p-i-n diodes each containing ten equally spaced and equally thick GaNAs QW layers. These layers were either Beryllium (Be) doped (p-type), un-doped or Silicon (Si) doped (n-type) respectively. Both AS and DLTS revealed deep level centers present in the devices. Each technique presented its own list of advantages and disadvantages and the collaborative use of both of them was found to be complementary in their determination of deep level defect centers. The correlation of these defects with the QWs is not clear as the structures were not optimized for capacitance spectroscopic measurements. NextNano++ simulation software was also used to theoretically model the electronic structure of the sample. The addition of the applied bias and its effect on the cross-over point of the Fermi level and the deep level energy, as well as the depletion width was investigated. This was a useful and essential tool for the interpretation of the results obtained and for the design of optimal structures for future studies.
- Full Text:
- Date Issued: 2018
Causes and impacts of delays in low-income housing projects in the greater Nelson Mandela Bay and Buffolo City Municipality
- Authors: Xongo, Nwabisa
- Date: 2018
- Subjects: Project management -- South Africa -- Nelson Mandela Bay Municipality , Project management -- South Africa -- Buffalo City Municipality Low-income housing -- South Africa -- Eastern Cape Public housing -- South Africa -- Eastern Cape Housing development -- South Africa Construction industry -- Management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/36259 , vital:33916
- Description: A construction project depends upon having correct people with the correct skills and usable equipment, therefore to deliver the project on time, on budget and specified quality. Project success can be attained if the construction works moves professionally within the time schedule. Delays to projects mean the go slow of process and all other related fields. The main aim of this study is to assess the numerous causes of delays and reasons for those delays that are currently affecting the project in low income housing projects in Nelson Mandela Bay and Buffalo City Metropolitan Municipality.
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- Date Issued: 2018
Challenges facing the state of construction health and safety management practices within the Eastern Cape: a case of the Sarah Baartman District
- Authors: Mafuya, Nomakhwezi
- Date: 2018
- Subjects: Industrial safety -- Management , Construction industry -- South Africa -- Eastern Cape Construction industry -- Safety measures -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/31532 , vital:31504
- Description: The construction industry has a poor Health and Safety (H&S) record globally and South Africa is no exception (Haupt, 2016: 1). The construction industry is integrally a high-impact and dangerous industry with less than a 50% ratio in compliance to H&S standards (PricewaterhouseCoppers (PwC), 2016). This study is aimed towards evolving a solution to mitigate the fatalities and injuries, occupational health hazards, non-compliance with legislation and design originated hazards and the reoccurring problems experienced by the Eastern Cape Department of Public Works (ECDPW) on projects. Literature points out that H&S performance is attributable to a lack of management commitment, inadequate supervision, inadequate H&S training, and lack of worker involvement (construction industry development board (cidb), 2009: 36). Huang and Hinze (2006: 179) contend that clients‟ participation in project H&S can significantly influence project performance. Various researchers have amplified the importance of leadership roles and involvement of clients in H&S. A quantitative survey and qualitative inquiry were utilised to gather and analyse data within the Eastern Cape province of South Africa. Three questionnaires were developed and distributed to a target population, and interviews were conducted. The study focuses on seven schools, namely; Stormsriver, Jubilee, Mfesane, Bongweni, David Livingstone, Kaiser Ngxwane and Bethelsdorp, which are on-going for the 2016/2017 financial period during which the research study was conducted. A total of 136 responses were used to analyse the data. All project stakeholders, namely: project managers, contractors‟ site managers, and workers contributed to the study. The frequency of H&S actions varied with each stakeholder dependent on the stage in which they were involved. The study determined that extensive inadequacy of construction expertise in terms of H&S including H&S consultants and departmental H&S personnel, inadequate management and supervision on site, inadequate workers participation, inadequate H&S training, inadequate expertise in H&S management, inadequate designer report, inadequate H&S knowledge and awareness, negligence, unsafe acts, unskilled workers, unsafe conditions, non-compliance with H&S regulations, Safe v Operating Procedure (SOPs) and Safe Working Procedures (SWPs), inadequate commitment of various project stakeholders, ignorance, poor client H&S leadership throughout certain aspects of the ECDPW projects are the primary cause of fatalities and injuries, ill-health, design originated hazards, non-compliance and the reoccurrence of problems. Recommendations were for H&S to be integrated within the Departments internal project systems from project inception to project close out, and to enhance H&S knowledge and skills in order to mitigate the reoccurrences of problems on projects.
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- Date Issued: 2018