4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item Design and development of a bioactive-loaded polymer-engineered neural device for potential application in reducing neurological deficits after spinal cord injuries and neuro-regeneration(University of the Witwatersrand, Johannesburg, 2017) Kumar, Pradeep; Choonara, Yahya Essop; Modi, Girish; Naidoo, Dinesh; Pillay, VinessTraumatic Spinal Cord Injuries (SCI), due to their devastating nature, present several interventional challenges (extensive inflammation, axonal tethering, scar formation, neuronal degeneration and functional loss) that need to be addressed before even a slight neuronal recovery can be achieved. Recent post-TSCI investigational approaches include support strategies capable of providing scaffold architecture to allow axonal growth and conformal repair. This research provided detailed insight towards the development and fabrication of six specialized Polymer-Engineered Neural Devices (PENDs): 1) poly(lactic-co-glycolic acid)-gliadin (PLGA-GLDN) nanofibrous mats, 2) polyacrylamidated chitosan (PAAm-g-HT) scaffold, 3) functionalized chitosan methoxypolyethylene glycol (CHT-mPEG) cryosponges, 4) polyacrylonitrile-elastin-collagen (PANi-EC) neurosponge, 5) methylcellulose-alginate-polyethylene glycol (MAP) thermogel, and 6) chitosan-luronic F127-β glycerophosphate (CHT-PF127-βGP) composite thermogel for potential restriction, repair, regeneration, restoration and reorganization post-SCI. The latest trends in biomaterials-based SCI intervention were reviewed, discussed and analyzed in detail throughout the thesis. The research also involved an in silico analytico mathematical interpretation of multi(biomed)material assemblies wherein quantification of energy surfaces and molecular attributes via atomistic, dynamic, and docking simulations was carried out. The in silico experimentation additionally confirmed the potential of curcumin as a bioactive of choice for SCI intervention. Curcumin and dexamethasone were incorporated into the compact scaffolds and the bioactive release was determined over a period extending up to 60 days. The PLGA-GLDN nanofibrous mats demonstrated the formation of a compatible blend among the component polymers at equal weight ratios (PG55) as confirmed by quantitative physicochemical characterizations. Image processing analysis (DiameterJ plug-in of ImageJ) was performed on the SEM images of nanofibers to quantify the size, porosity, and orientation of the samples. Nanofibers within the size range of 10nm and 250nm were obtained in case of compatible blend and the nano stack was used for in vivo implantation post-SCI. Polyacrylamidated chitosan (PAAm-g-CHT) was synthesized via a unique persulfate-mediated polymer slicing and complexation as determined by static lattice atomistic simulations. The graft copolymer so obtained was fabricated into an anisotropic neurodurable scaffold. The CHT/mPEG cryosponges showed unique morphological features such as fringe thread-like structures (CHT alone); hemispherical, pebble-like structures (CHT-mPEG); curved quartz crystal-like or crystal-flower-like structures (CHT-mPEG-CHO); and grouped, congealed, steep-sided canyon-like structures (CHT-mPEG COOH). A novel image processing protocol involving DiameterJ and ND plugins of ImageJ software was employed for analyses of the SEM micrographs in terms of % porosity, pore wall thickness and % xiiehaviorxii of the porous scaffolds. The PANi-EC interpenetrating polymer network neurosponges were synthesized employing free radical polymerization under acidic conditions wherein first-in-the-world spinomimetic scaffolds were obtained. The unique feature of the PANi-EC neurosponge was the formation of a fibrous neurotunnel architecture mimicking the native spinal cord. The physicochemical characterization revealed that the secondary structure of the peptide molecules (elastin and collagen) rearranged in the presence of PANi to their native extracellular matrix (ECM) form confirming the self-assembling nature of the polymer-peptide architecture. Furthermore, the PANi-EC neurosponge provided a perfect balance of matrix resilience and matrix hardness similar to the native collagen-elastin complex in vivo. Two very interesting tri-component thermogels were reported here viz. a simple blend thermogel comprising methylcellulose, sodium alginate and poly(ethylene glycol) and a complex thermogel incorporating chitosan, Pluronic F127 and β-glycerophosphate. Both the thermogels solidified at physiological temperature confirming their applicability in vivo. The outstanding feature of MAP thermogels was the formation of hydrogen bonded O-H…C=O which only formed in the tripolymeric blend while the bipolymeric blends showing no such interaction. We proposed that the MAP thermogel self-assembled into a repeating network structure represented by “PEG400-ALG-hydrophillicMChydrophobic}-{hydrophobicMC-hydrophilic}-ALG-PEG400” and the physical “compression” might have led to the formation of hydrogen bonded O-H…C=O among MC/alginate or PEG/alginate in the presence of PEG or MC, respectively. In case of the complex CHT/PF127/βGP thermogel, a unique triphasic gel-sol-gel transition xiiehavior was observed with the thermogel forming a gel-phase at lower temperatures (T<20°C), a sol-phase at intermediate temperatures (20°C35°C). The MTT proliferation studies indicated that all polymer engineered neural devices (PANi-alone matrix) were capable of efficiently supporting the growth of PC12 cells compared to the control over a period of 72 hours. The fundamental objective of this thesis was to test the applicability and capability of various biomaterial composites towards the repair and regeneration of neuronal tissue after traumatic spinal cord injury. Although drug-loaded scaffolds were also developed, only drug-free scaffolds (PLGA-Gliadin 5:5 electrospun nanofibers; PANi-Elastin-Collagen neurosponge; and Chitosan/Pluronic F127/β-glycerophosphate thermogel) were tested in vivo for the proof-of-concept. The 21-point scale BBB locomotor rating analysis demonstrated that PEND I (14), PEND II (19) and PEND III (18) provided significant motor recovery as compared to the lesion-control (5) group 28 days post-SCI and –implantation. The immunohistochemistry confirmed that reparative changes were accompanied by marked upregulation of iNOS, a notable influx of ED1-positive chronic inflammatory cells, the appearance of multinucleate cells characteristic of presumptive regenerative neuroblasts and near-complete loss of GFAP and NF-200 protein/structural integrity. Almost complete functional and neurostructural recovery was observed with post-SCI implantation of PEND II and III. In conclusion, the composite scaffolds tested in this research demonstrated immense potential in improving the neurological, neurochemical, and behavioral outcome after implantation post-SCI.Item Financial inclusion in South Africa: An analysis of the financial sector regulatory framework and proposals for reform(2018-09) Duma, Amanda; Kawadza, HerbertAbstract Not Available.Item Surgical aortopulmonary shunts - a thirty-seven year experience in a South African tertiary institution(University of the Witwatersrand, Johannesburg, 2019-11) Dladla-Mukansi, Nontobeko Charity; Cilliers, Antoinette; Mammen, Vijay; Vanderdonk, KathyIntroduction: The surgical aortopulmonary shunt is a valuable palliative procedure in the management of congenital heart diseases. There is a paucity of data regarding aortopulmonary shunts in the developing world, including South Africa. Objectives: The primary objective was to describe the demographic, clinical and echocardiographic characteristics of children between ages 0 and 14 years that underwent surgical aortopulmonary shunts. The secondary objectives were to describe trends in aortopulmonary shunt designs, outcomes in terms of morbidity and mortality, progression to definitive surgery and to assess patency of shunts. Material and Methods: A retrospective clinical audit of patient files who underwent an aortopulmonary shunt between 01 January 1980 to 30 December 2016 was undertaken at Chris Hani Baragwanath Academic Hospital (CHBAH) in Soweto, Johannesburg. The study period was divided into 3 stages and for descriptive purposes as follows: 1980-1991 refers to period 1, 1992-2003 refers to period 2 and 2004-2016 refers to period 3. Results: A total of 177 aortopulmonary shunts were done over the 37-year study period. Of these 177 patients, 165 (93.2%) patient files were available. Fifty-six percent of the patients included in the study were male. The majority of patients were from the Gauteng Province (76.8%). The four most common diagnoses across the entire study period were tricuspid atresia (26.0%), pulmonary atresia with VSD (23.7%), tetralogy of Fallot (23.2%) and complex cardiac lesions (16.9%), with no particular trend in the proportion of these diagnoses presenting across this study period. There was no statistical difference between period 1 and 2 (p-value a=0,328) and between period 1 and 3 (p-value b=0,548). The total number of all surgeries done over the entire study period was 2145, of which 8.3% were aortopulmonary shunts. Period 1 had the highest percentage [35 (10.9%)] of aortopulmonary shunts compared to the total number of surgeries performed. There was a decline in the number of aortopulmonary shunts performed over the study periods 1-3. With no statistical difference across periods as shown in table 1 with p-value a and b. Of the different types of aortopulmonary shunts, most patients [157 (88.7%)] had a modified Blalock-Taussig shunt (BTS). The remainder of the shunts included 3 (1.7%) classic BTS, 12 (6.8%) central shunts and 5 (2.8%) unknown BTS. The percentage of modified BTS done increased from 80% in period 1 to 87.3% in period 2 and to 95.2% in period 3. Period 1 had the most complications (28.6%) compared to 11.4% in period 2 and 19.1% in period 3. Sepsis as a complication following surgery increased over the study period from 2.9% in period 1 to 3.8% and 7.9% in periods 2 and 3 respectively. Early mortality was 17.1%, 26.6% and 25.4% from periods 1-3 respectively. Late mortality declined from 17.0% in period 1 to 11.4% and 0% in periods 2 and 3 respectively. Only 37 (20.9%) patients were documented to have further surgery after the initial aortopulmonary shunt. Across all three study periods, no blocked shunts were documented. Conclusions: This study describes the characteristics and outcomes of aortopulmonary shunts over a 37-year period in a tertiary care resource limited low to middle income country setting. The commonest cardiac lesions for which aortopulmonary shunts are performed are tricuspid atresia, pulmonary atresia with VSD, tetralogy of Fallot and other complex cyanotic cardiac lesions. The frequency of aortopulmonary shunts compared to total surgeries has corrective surgery for these cardiac lesions. The modified BTS is the most frequently performed aortopulmonary shunt used for palliative surgery in our setting, which is a similar trend in developed countries. The morbidity and mortality in this study is higher than developed countries, with sepsis being the most common complication. Attention to infection control practises need to be emphasized peri- and post-operatively in our hospitals.Item The influence of Entrepreneurial Capital on the performance of subcontracting SMMEs in Gauteng, South Africa(University of the Witwatersrand, Johannesburg, 2019-03) Rampa, Mmatsatsi; Galawe, JabulileThis study explores the prospect of entrepreneurial capital in stimulating SMME performance. It seeks to investigate the use of non-financial capital (entrepreneurial capital) in SMMEs registered under the CIDB, in the general building sector, and its influence on SMME performance. It unpacks the two dimensions of entrepreneurial capital which are entrepreneurial commitment and entrepreneurial competence. This study is a quantitative research, based on a positivism research paradigm. The survey structured research instrument was collected using Qualtrics. The primary data, with a sample size of 377, was distributed using emails and was consolidated via Qualtrics. The data analysis and interpretation was based on descriptive analysis, correlation analysis, exploratory analysis and multiple linear regression analysis. The study was initially designed to analyse the two dimensions (entrepreneurial competence and commitment) collectively with their antecedents (opportunity, relationship, conceptual, organising and strategic competencies); and (normative, continuous and affective commitment) respectively. The survey findings could not converge into a clear multi-dimensional factor structure for each construct. Hence the analysis could only be undertaken at the dimensions level without breaking them down any further into their sub-sets. Entrepreneurial competence was the only one of the two that emerged as the statistically significant predictor of SMME performance. However, both dimensions had a positive influence with business performance, though entrepreneurial commitments’ influence was weak and not statistically significant. SMME owners/managers should continuously advance and assess their specific entrepreneurial competence in order to positively influence their business performance. Policy makers, training and support programmes should align content to specific entrepreneurial competence.Item The Case of Analytic Philosophy as ‘the Philosophy’ and Its Problem for the Decolonization of the Curriculum(University of the Witwatersrand, Johannesburg, 2018) Ramaphala, Dorcus; Etieyibo, EdwinIn this research, I shall be examining two related issues. The first issue is about whether the presentation of analytic philosophy as the proper and only method of doing philosophy is justified. The second concerns the problems posed for the decolonization of the philosophy curriculum by this hegemonic and triumphant position of analytic philosophy as “the philosophy.” My motivation for engaging with these issues is to try and make the case for other philosophical traditions and methods, including African philosophy as legitimate and proper philosophical enterprises even when they do not share all or some of the traits and features of analytic philosophy. Success in making this case seems crucial to the project of decolonizing the philosophy curriculum.Item Men, Masculinity, Aggression and Dominance: An Exploration of How Young Men are Socialized to Deal with Situations of Man-on-Man Aggression and Dominance(University of the Witwatersrand, Johannesburg, 2019) Vilakazi, Zinhle; Davies, NickThere is a considerable body of research placing young South African men at the core of interpersonal violence. Within these studies they are frequently positioned as both perpetrators and victims of extreme and homicidal modes of aggression. In light of this gendered nature of interpersonal violence, this study was directed at exploring how young men’s responses to a situation of man-on-man aggression and dominance might be linked to how society encourages or expects a certain masculine performance from men in such situations. This study’s secondary goal was to offer some ideas about how young men might establish a masculine identity through aggression and dominance. In the pursuing research aims, a total of 14 young adult men attending university participated in this qualitative study. From the analysis what became evident was the continuous pressure that young adult men experience in society, through various social institutions, to somehow fit into dominant or hegemonic constructions of masculinity. Within the context of this study, the proximal cause of aggression and dominance was attributed to broader concerns regarding presentation of a masculine identity, self-worth and social status.Item Exploring the use of Process Drama in dialogues on Race and Memory among black ‘Born Frees’ of South Africa(University of the Witwatersrand, Johannesburg, 2018) Radebe, Tebogo; Lepere, RefiloeThis research project examines the use of Process Drama in creating dialogue about race and memory among Black Born Frees in South Africa. Process Drama was used as a dialogue facilitation tool, which involved both participants and a facilitator in role. The study further unpacks how process drama impacted participants’ attitudes on race and memory. Reflective practice is employed to interrogate how Process Drama creates empathy, to enable reflection on lived experiences, to lead to an examination of stereotypes around race and memory through constructive dialogue. The research focuses on the facilitation of improvised, episodic scenes and creation of images structured around themes of race and memory leading to post 1994 democratic South Africa. From the facilitation process, it emerged that improvisation in the dramatic action enables dialogue by allowing the participants to raise each other’s awareness by sharing various perspectives and understandings. Using a Process Recording as a tool for analysing the facilitator in action the paper makes a case for performative writing as way to present the process and findings of the research. The method of allowing the participants voices to be heard and validated began a process of healing psychological and emotional wounds among the black born frees.Item Characterisation of a geothermal resource at Kwako Hills in Zambia using magnetic and natural source audio magnetotelluric methods(University of the Witwatersrand, Johannesburg, 2019) Chinamora, Blessing; Dr Jones, Mike; Prof Webb, SusanThe announcement by the Zambian government that geothermal energy will be recognized as an energy source in the 2013 national budget drew a lot of attention to investors and scientists. Since the 1950s reconnaissance geoscientific surveys have been carried out on geothermal targets in Zambia by the Geological Survey of Zambia (GSZ). The GSZ, together with an Italian company (DAL, SpA), studied various hot springs (Legg, 1974) and as a result, various prospects have been considered for development or exploration. In this research, the Kwako Hills prospect which is located near Mumbwa district, about 150 km northwest of Lusaka, hosts two hot springs which are good surface manifestations for geothermal energy potential was investigated for its geothermal energy reservoir potential using magnetic and natural source audio-magnetotelluric (NSAMT) geophysical methods. The focus of these surveys was on examining the structural controls that govern the occurrence of the hot springs and the outcropping Hook Batholith just to the north of the east-west trending alluvium filled valley. The northern branch of the alluvium valley has a northwest–southeast trend which is the same as the minor fault controlling the two hot springs. These structural controls increase the vertical permeability in the area causing the thermal waters to circulate to depths where they acquire their heat. Permeability is high at intersections of faults and fracture zones, intersection of major and minor faults or intersection of faults and sedimentary aquifers. Major ENE and NE trending faults were mapped along the Mwembeshi Shear Zone and the boundary between the Hook Batholith and the Katanga sediments respectively. The area is underlain by foliated basement granitic gneiss, Hook Batholith granites and Katanga metasediments that are broken into fractures along the foliation trends that control the occurrence and flow of rivers and streams. Overlying the basement rocks are the recent Karoo and Kundelungu sediments which are also permeable along the bedding or cleavage planes. The vegetation pattern, flow and occurrence of rivers or streams reflect trends of zones of weakness in the basement. Fractured zones developed along these foliations and were mapped at outcropping scale using Google Earth, aeromagnetic and ground magnetic data interpretation. Interpretation of aeromagnetic data confirmed the foliation trends that were suggested by Abell (1970) and Naydenov et al. (2014). One dimensional (1D) and two dimensional (2D) magnetotelluric (MT) resistivity models were created on the basis of a 120 MT sounding data set. A dimensionality and distortion analysis of the NSAMT data was carried out based on the approach of Groom and Bailey (1989) and it was concluded that the data were collected almost perpendicular to strike, which is also supported by the geological mapping. MT smooth inversion models showed the lateral and vertical extent of the potential geothermal reservoir. Different 2D MT inversion approaches were applied to investigate the lateral continuity of the conductive sedimentary layer of the Kundelungu unit (slate, siltstone and shale). In order to map the subsurface structure of the area, a magnetic model was then produced using the acquired ground magnetic data and constrained using magnetic susceptibility measurements, MT data and geology mapped on the surface. Magnetic data interpretation confirmed an NW-SE fault controlling the hot springs, which was mapped using the NSAMT inversion results. The research shows that there is a lateral conductive, water saturated zone (reservoir) present between 150 m and 550 m depth and deeply seated faults in the basin. Along the deeply seated faults the conductive zones are vertical and continue with depth. The information shows that the thermal waters of the hot springs appear to circulate to depths more than 2.5 km along deep seated faults and foliation fractures penetrating the foliated rocks of the Hook Batholith and basement rocks. This water is heated by the regional geothermal gradient of 23ºC/km. Further exploration can be carried out on the study area to prove its potential for a geothermal resource.Item Experiences of positive psychology coaching for women’s success in workplace(University of the Witwatersrand, Johannesburg, 2018) Mokwele, MapasekaThe findings of the study revealed that positive psychology coaching assists the coachees in their ability to develop positive thinking; it helps to improve confidence and resilience, enhances self-awareness and interpersonal skills, enhances learning and knowledge and also enhances decision making skills. Despite this, there were challenges that were highlighted during the use of positive psychology coaching. There were three core challenges that were revealed by the findings, which were the personal coachee challenges, environmental challenges, as well as the PPC tools and methodology challenges. The findings show there were overall benefits which entailed higher level of self-awareness and control where the coachees were able to tap into their strengths, increased their energy, eliminated negative thoughts and felt empowered in so far as being able to achieve all their desires. It is evident that positive psychology coaching is a vital tool for women in leadership as it enhances their ability to go for what they want and believe in themselves, thereby reaching their optimum psychological aspects resulting in success in the workplaceItem Early-stage entrepreneurs’ marketing activity in South Africa(University of the Witwatersrand, Johannesburg, 2019) Botha, Jamie-Lee Ann; Mazonde, NomusaPurpose: This paper explored the unique characteristics of the marketing function of early-stage entrepreneurs operating in South Africa. Methodology/approach: A qualitative study was done. The data was collected by doing unstructured face-to-face interviews to conceptualise the unique marketing activities of early-stage entrepreneurs operating in the South African market. Findings: The study indicated that entrepreneurs do digital marketing; however, the primary marketing activity is the ‘on the ground’ marketing. Entrepreneurs still execute old fashioned, cold calling and relationship building with the customer at the centre of the business. Entrepreneurs boasted of their agility to adopt new technology and offer personalised service and product packages to meet the customer’s needs. Value: This paper uncovered the marketing activities of early-stage entrepreneurs and highlighted the marketing areas that need improvement. The results will assist entrepreneurs in the early business development stages with their marketing endeavours and enhance the business performance. The research contributed to the domain of entrepreneurial marketing