4. Electronic Theses and Dissertations (ETDs) - Faculties submissions
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Item Surface Brillouin scattering studies of high-temperature elasticity(University of the Witwatersrand, Johannesburg, 1999-03) Stoddart, Paul Randall; Comins, J. DarrelA novel technique has been developed for studying the elastic proper ties of opaque solids at high temperatures. The method is based on surface Brillouin scattering (SBS) and has the advantages of being contact-free and non-destructive. The elastic constants can be extracted from SBS measurements of the directional dependence of the surface wave velocities. An optical furnace was designed to provide the special scattering geometry required for these measurements. The technique has been evaluated on silicon and a single-crystal nickel-based superalloy, with measurements up to 800°C and 200°C respectively. Above these temperatures, measurements were precluded by a marked deterioration in the surface quality. The elastic constants for silicon compare favourably with the established ultrasonic values, particularly in terms of the changes as a function of temperature. Additional measurement were performed on silicon at temperatures up to 900°C in order to examine the well-known central mode feature. These results shed light on a major outstanding problem in SBS, because they reveal the presence of a second quasielastic mode that may be associated with scattering from diffusive excitations. Further measurements at high and low temperatures are proposed to confirm the mechanism. Silicon was also used as a test system to clarify certain aspects of the theory and practice of SBS that have not been properly dealt with before, such as the effects of surface anisotropy and of the extended collection aperture. This indicates that SBS provides effective elastic constants for the outer 300 nm of the sample surface and thus may be influenced by surface damage and surface contamination. In the case of the superalloy, the difficulties encountered in gathering data at higher temperatures suggests that modifications to the furnace arrangement are required. The larger relative error in the velocities also created problems in the extraction of the elastic constants. This difficulty was satisfactorily overcome by using the longitudinal threshold in the Lamb shoulder to fix the value of c₁₁. Although the work described here has been limited to temperatures below 900°C, it is clear that SBS provides a powerful method for probing the elastic properties of opaque solids at elevated temperatures.Item How Diversity and Inclusion May Transform South African Commercial Property Organisations at Top Management Level(University of the Witwatersrand, Johannesburg, 2017-08) Motshegare, Reabetswe Regina; Levy, DeborahThe purpose of this report is to outline contemporary transformation frameworks that emphasise diversity and inclusion and how the latter may likely transform Growthpoint Properties South Africa (Growthpoint S.A). The main focus of the consultancy report is to compare and contrast traditional transformation methodologies and contemporary diversity and inclusion methodologies as strategies to assist Growthpoint S.A transform its senior and executive management. The propositions are that; an effective transformation strategy for Growthpoint S.A is one that focuses on identification; inclusion; attraction; diversification and retention of key talent at senior levels. Furthermore, that once diversity and inclusion interventions are implemented, there will be transformation at senior and executive levels. Out of 15 executives in the management team, six representatives were interviewed. The limitations highlight that the majority of participants are South African and may have certain biased perceptions about the topic as opposed to the rest of the participants, who are foreign nationals. The methodology focuses on a thematic analysis and four themes namely: leadership; corporate culture; strategies and communication are identified. Following in-depth discussions, six recommendations are provided. These include 360-degree feedback; diversity and inclusion workshops; introduction of a diversity and inclusion forum; KPI’s that measure diversity and inclusion targets; workplace enhancement programmes that focus on diverse candidates and lastly, robust succession plans. The role of the researcher as a professional Human Resource Business Partner ensured that any work dealt with is approached ethically, and the researcher’s ability to do this ensured quality, reliability, validity and effectiveness of the research.Item Bypassing the union: An Employer's Right to Negotiate Directly with Striking Employees(University of the Witwatersrand, Johannesburg, 2016-08) Nkosi, Thulani Gift; Mahomed, ShahedaSouth African labour law influenced by the Constitution and notions of equity and fairness has undergone a total change and will, without doubt, continue to change to meet the ever changing nature of employment it seeks to regulate. It is after all in the nature of all laws to change with the society they seek to regulate and our labour law is no exception. Recently, focus has shifted to the institution of collective bargaining and the questions posed are whether our labour laws as they currently stand are capable of adequately regulating the process of collective bargaining in such a way that the main objective of collective bargaining which is to bring about industrial peace is promoted and maintained at all times. These questions are posed on the back of the unprecedented spates of prolonged violent strikes that have resulted in the destruction of property and loss of life as well as unimaginable financial losses not only for the employers affected but also for the economy as a whole. These unprecedented prolonged violent strikes have caused employers to engage in bargaining conduct that could erode the participation of trade unions from the collective bargaining process which bargaining conduct takes the form of employers bypassing trade unions and negotiating with striking employees directly. But do employers have a right to bypass trade unions in this way? This paper investigates this question against the background of the case of Amcu v Lonmin where the Labour Court on application by a trade union had to decide whether to grant an urgent interdict restraining employers from negotiating directly with striking employees. The employers considering themselves to be acting within their rights opposed the application. The Labour Court unfortunately dismissed the application on technical grounds relating to the lack of urgency without considering or deciding this question. This paper accordingly picks up the debate; considers the historical evolution of collective bargaining in our labour law including the voluntarist argument that is said to be embodied by the Labour Relations Act (LRA), and concludes that when all things considered employers in fact do not have a right to bypass trade unions. If employers had this right certain provisions of the LRA that guarantee trade union participation would be rendered nugatory and the whole collective bargaining process would become unworkable. The LRA envisions that once parties have voluntarily embarked on collective bargaining they bargain in good faith and do not bypass each other.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.