Determinants of export performance among small to medium enterprises in Zimbabwe
- Authors: Karambakuwa, Tapuwa Roseline
- Date: 2017
- Subjects: Economics -- Zimbabwe Small business -- Zimbabwe -- Management , Shipping -- Economic aspects -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/17647 , vital:28424
- Description: There is consensus that Small to Medium Enterprises (SME) exports play a critical role in the development of economies. It has been widely acknowledged in empirical research done around the world that small businesses make a significant contribution to economic development, employment, competitiveness and the reduction of regional disparities. However, empirical literature gives conflicting evidence on the determinants of export performance among SMEs. The study contributes towards the debate on SME exports by: (i) investigating the variables that determine export performance among SMEs in Zimbabwe (ii) establishing the competi-tiveness of Zimbabwe’s exports and (iii) ascertaining the major constraints faced by SME ex-porters in Zimbabwe The researcher gathered data from 120 SMEs and 10 institutions in Zimbabwe for the period 2009 to 2015. SME samples were chosen from Harare, Mashonaland Central and Mashonaland East provinces while all 10 of the institutions were chosen from Harare province. Convenient non-probability sampling method was used to select SMEs while stratified sampling technique was applied in the selection of institutions. Both qualitative and quantitative research methods were employed. For the quantitative approach, panel data ordinary least squares method was used in the form of the gravity model of trade. Export intensity (used as a measure of exports) was regressed against support institutions, business ownership, research & development, educational years, use of export processing zones, product type, export years, firm size, firm age, gender, distance from trading partner, Gross Domestic Product (GDP) of trading partner, and GDP of Zimbabwe. The random effects estimation method was used, basing on results from the Durbin-Wu-Hausman test. The null hypothesis was based on the premise that the variables under study do not determine export intensity of SMEs in Zimbabwe. Other null hypothesis were that the major constraint faced by SME exporters in Zimbabwe is not access to finance and that Zimbabwe’s exports are not competitive in the mining, agricultural and manufacturing sectors. The revealed comparative advantage index was computed to measure the competitiveness of Zimbabwe’s exports.For the qualitative approach, the study used the triangulation method which involved combining and utilising the questionnaire, interviews and focus group discussions. The results from the study indicated that following variables increased export intensity of Zimbabwean SMEs; business ownership, use of export processing zones, export years, firm size, and GDP of trading partner. The following variables have an inverse relationship with the export intensity of Zimbabwean SMEs: gender, distance from trading partner and research & development. The results also indicated that these further variables do not determine the export intensity of SMEs in Zimbabwe: support institutions, years of education, product type, firm age and GDP of Zimbabwe. The major constraint faced by exporting SMEs in Zimbabwe is limited access to finance. Zimbabwe is competitive in the agricultural and mining sector exports, but not in manufacturing sector exports The policy implication of the findings is that SME support needs to go beyond support institutions when it comes to SME export promotion. Further SMEs in the agriculture and mining sectors need to be promoted for export growth since Zimbabwe is competitive in these sectors. However the manufacturing sector cannot be ignored, since many economies have developed due to exports of manufactured products and a country needs to have balanced export growth in both primary and manufacturing sectors. In order to have motivated, career SME exporters, entrepreneurship education should begin from primary school right up to university so as to improve entrepreneurial aspirations, attitudes and behaviour in the long run.
- Full Text:
- Date Issued: 2017
Determinants of internet banking adoption by banks in Ghana
- Authors: Bart-Williams, Edem
- Date: 2015
- Subjects: Internet banking -- Ghana , Banks and banking -- Ghana , Banks and banking -- Automation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/3715 , vital:20457
- Description: Growth in information and communication technology (ICT) is drastically changing the way businesses, especially in the service industries, are conducted. The financial services industry and banking in particular, is not excluded from this technology explosion. Internet banking, even though not new in advanced countries, is a new transaction channel being used by banks in some parts of Africa, especially Ghana, to offer various products and services to their customers. However, this medium has not been fully exploited by these banks as there are many hurdles the banks must triumph over. In deploying this technology and these systems, there are several factors which banks must take into consideration before fully deploying such a system to their customers, hence the motivation for this study. The absence of suitable and sufficient knowledge on this topic also exposes a “rhetoric versus reality” argument of whether the intention to adopt Internet banking is critical to the strategies and ultimate success of banks in Ghana. For banks to stay ahead of competition as well as to attract and maintain their clientele, it is of paramount importance to gather and link the perspectives of both clients and bank managers in order for banks to ensure that they perform according to the needs and expectations of their clients. In order to achieve the intended results, an empirical study was conducted by taking into consideration the viewpoints of both bank clients and bank managers in determining the factors that customers take into consideration before adopting the Internet banking medium. The primary aim of this study was to quantify significant relationships between the selected variables. Therefore the positivism research paradigm was used, while the phenomenological paradigm was employed for the measuring instruments. Because multiple sources of data were used, from the perspectives of banking clients and managers in Ghana, methodological triangulation was adopted for this study. The results of the empirical investigation showed that both groups (clients and managers) considered the variables of market share, technology acceptance, diffusion of innovation, organisational variables, organisational efficiency, and business strategy to have direct influence on the adoption of Internet banking. However, they differed in opinion concerning the degree of influence of these variables. The bank managers’ responses leaned more towards strong agreement with the importance of these variables than did those of the bank clients. Thus, for bank clients to readily adopt the Internet banking medium for their banking transactions, bank managers must take a closer look at these determinant factors described in the study. The study showed that the population group, educational and income levels exerted an influence on the perceptions clients have regarding Internet banking adoption factors. It was found that the higher the education and income levels of the clients, the easier it was for them to adopt Internet banking. Also, the male group dominated the use of the Internet banking. This is supported by the fact that there is a growing middle class in Ghana that falls within this category of banking clients.
- Full Text:
- Date Issued: 2015
Developing an e-health framework through electronic healthcare readiness assessment
- Authors: Coleman, Alfred
- Date: 2010
- Subjects: Health -- Computer network resources , Medical care -- South Africa -- Computer network resources , Public health -- South Africa -- Computer network resources , Internet in medicine -- South Africa , Medical informatics -- South Africa , Telecommunication in medicine -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9729 , http://hdl.handle.net/10948/1519 , Health -- Computer network resources , Medical care -- South Africa -- Computer network resources , Public health -- South Africa -- Computer network resources , Internet in medicine -- South Africa , Medical informatics -- South Africa , Telecommunication in medicine -- South Africa
- Description: The major socio-economic development challenges facing most African countries include economic diversification, poverty, unemployment, diseases and the unsustainable use of natural resources. The challenge of quality healthcare provisioning is compounded by the HIV/AIDS pandemic in Sub Saharan Africa. However, there is a great potential in using electronic healthcare (e-health) as one of the supportive systems within the healthcare sector to address these pressing challenges facing healthcare systems in developing countries, including solving inequalities in healthcare delivery between rural and urban hospitals/clinics. The purpose of this study was to compile a Provincial E-health Framework (PEHF) based on the feedback from electronic healthcare readiness assessments conducted in selected rural and urban hospitals/clinics in the North West Province in South Africa. The e-healthcare readiness assessment was conducted in the light of effective use of ICT in patient healthcare record system, consultation among healthcare professionals, prescription of medication, referral of patients and training of healthcare professionals in ICT usage. The study was divided into two phases which were phases 1 and 2 and a qualitative design supported by a case study approach was used. Data were collected using different techniques to enhance triangulation of data. The techniques included group interviews, qualitative questionnaires, photographs, document analysis and expert opinions. The outcome of the assessment led to the compilation of the PEHF which was based on Service Oriented Architecture (SOA). SOA was chosen to integrate the hospitals/clinics‟ ICT infrastructure yet allowing each hospital/clinic the autonomy to control its own ICT environment. To assist hospitals/clinics integrate their ICT resources, this research study proposed an Infrastructure Network Architecture which clustered hospitals/clinics to share common ICT infrastructure instead of duplicating these resources. Furthermore, processes of the e-health services (e-patient health IV record system, e-consultation system, e-prescription system, e-referral system and e-training system) were provided to assist in the implementation of the PEHF. Finally, a set of guidelines were provided by the research study to aid the implementation of the PEHF.
- Full Text:
- Date Issued: 2010
Developing the marital life course perspective as a conceptual framework for describing and understanding marital life events and marital transitions
- Authors: Rautenbach, John Victor
- Date: 2015
- Subjects: Marriage , Marital status , Married people
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/2991 , vital:20384
- Description: This research seeks to explore the development of the Marital Life Course Perspective as a conceptual framework for describing and understanding marital life events and marital transitions. The study’s orientation is guided by the Life Course Perspective (Glen Elder Jr.) as a theoretical framework and draws on Interpretative Phenomenological Analysis (Jonathan Smith) and Concept Analysis (Walker & Avant) as methodological approaches. One hundred and thirty (130) academic works that use the term marital life course in their texts constituted a literature-dataset for a Concept Analysis (Walker & Avant, 1988; 2011) that tracked the theoretical development of the Marital Life Course Perspective since 1980 (George, 1980, p. 80). The residents of retirement centres and old age homes in East London and Buffalo City (all older than 65 years of age) were invited to share a retrospective history of their relationship experiences, about their multiple marital life events and the marital transitions that shaped their marital life course. The 16 women who participated in the in-depth interviews had all been previously married more than once and were currently single due to divorce or the death of their husbands. This empirical data was analysed using Interpretative Phenomenological Analysis (IPA) as a guide (Smith, Flowers, & Larkin, 2009). After the analysis and synthesis of both datasets the following proposed operational definition of the Marital Life Course Perspective was constructed: The Marital Life Course Perspective is a conceptual framework for describing and understanding marital life events and marital transitions. As a subset of the Life Course Perspective, the Marital Life Course Perspective seeks to understand all stages of the marital experience within their wider social and cultural contexts, which are shaped by the historical dimension of a cohort’s specific time and geographic location. Marital life events include, but are not limited to, marital status changes. An individual may experience multiple marriage life events throughout their life, each with associated role transitions that vary according to their temporality and the individuals whose lives are linked to the marital experience. Well-being and transition outcomes across the marital life course may be promoted or impeded by an interplay of risk and protective factors, and agency-related capacity or resilience.
- Full Text:
- Date Issued: 2015
Development and evaluation of the coach-athlete relationship enhancement intervention
- Authors: Kuit, Wim
- Date: 2018
- Subjects: Interpersonal relations , Coaching (Athletics) -- Psychological aspects Sports -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/22508 , vital:29989
- Description: An expanding body of sport psychology theory and research has highlighted the central role of the coach-athlete relationship (CAR) in the performance, satisfaction and well-being of coaches as well as athletes. Models have been developed that identify the key dimensions of CAR quality and the interpersonal behaviour that maintains it, but there remains a need for interventions that support coaches and athletes to optimise their interpersonal skills. This can be done by harnessing recent advances in personality theory which emphasise a more holistic and developmental view of the person and provide a basis for greater mutual understanding and adaptive interpersonal behaviour change in the CAR. The aims of this study were to develop the Coach-Athlete Relationship Enhancement (CARE) intervention through an integration of the Enneagram personality typology with current models of the CAR, and then to evaluate the impact of the CARE intervention on CAR quality. Sixty-two university-level athletes and their nine coaches participated in the study. Quantitative and qualitative results indicate that the CARE intervention significantly enhanced CAR quality, including direct and meta-perceptions of closeness, commitment and complementarity, as well as co-orientation. Intervention outcomes included enhanced mutual understanding in the CAR, enhanced self-awareness, enhanced team relationships, and adaptive interpersonal behaviour change. These outcomes were associated with a shared awareness between coaches and athletes of their Enneagram personality type traits and motivations. Coach-athlete relationship quality was further enhanced by re-constructing coaches’ and athletes’ personal narratives based on self-descriptions of Enneagram type strengths, and a redefinition of individuals’ core motivations to incorporate adaptive interpersonal behaviour change.
- Full Text:
- Date Issued: 2018
Development of a community pharmacy experiential learning programme in a South African context: a design research approach
- Authors: Kritiotis, Lia Costas , Thesis Advisor
- Date: 2018
- Subjects: Pharmacists -- Training of , Experintial training , Community development -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/17481 , vital:28353
- Description: Application of the design research approach to devise, develop and optimise an experiential learning programme and adaptation of the Volunteer Functions Inventory (VFI) to understand community pharmacists’ motives, are unique contributions to the global pharmacy education setting. This study generated new theory, in the form of substantive and procedural claims (design principles) regarding experiential learning programmes and preceptor and student motivation in a South African pharmacy educational context, which can be added to the existing international landscape and more importantly, plant the foundational seeds of insight that can be utilised as guiding tools by other South African pharmacy faculties.
- Full Text:
- Date Issued: 2018
Development of a creep sample retrieval technique and friction weld site repair procedure
- Authors: Wedderburn, Ian Norman
- Date: 2013
- Subjects: Friction welding
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9635 , http://hdl.handle.net/10948/d1020116
- Description: The remnant life monitoring of creep loaded high temperature and pressure components in power stations is critical to ensuring their safe and cost effective operation as failures can have severe consequences. Effective creep life condition monitoring allows for optimising component life predictions and subsequent plant maintenance decisions. In South Africa many power generation stations have been in operation well beyond their 30 year design service life, as such knowledge of the remnant creep life of high temperature and pressure components, such as steam pipelines, becomes of utmost importance. Techniques for the remnant creep life assessments of critical high temperature and pressure components must therefore be as effective as possible. The common and well accepted in-situ inspection technique for assessing creep damage in steam pipes is by the metallographic replication technique. The technique is however limited to the outer surface of the pipe, without information on damage within the wall. This research will illustrate a means of obtaining a sample for creep life analysis with depth through the wall of a pipe, as wells as an alternative technique for the repair of the sample retrieval site. A sample retrieval technique was developed that would retrieve a small diameter cylindrical sample from a cored blind hole for creep analysis by visual creep void assessment or by the small punch creep test. The small punch creep test requires only a small diameter thin disc of material for testing for which its results are comparable with conventional uniaxial creep testing which requires a much larger sample of material. The smaller sample requirement of the small punch creep test therefore allows for a vastly reduced invasive sample retrieval operation and consequently smaller repair size area. Also the fact that the sample is retrieved from a blind hole is advantageous since the pipe wall is not penetrated which would require full plant shutdown. A friction welding technique was identified as an alternative to traditional arc fusion welding for the repair of the sample retrieval site, this technique being the Friction Hydro Pillar Processing technique. Friction Hydro Pillar Processing is a solid-state welding technique and as such has a number of inherent benefits over arc fusion welding as the weld is performed below the melting temperature of the material. From a process point of view Friction Hydro Pillar Processing is ideally suited for automation, has virtually no fumes generated, minimal distortion is experienced and no spatter has to be removed afterwards. The technique has yet to see industrial application and as such development of suitable process parameters was undertaken. Finally, to apply the sample retrieval and repair operations in-situ to a steam pipe in a power plant suitable equipment was developed. Existing friction welding equipment is generally bulky workshop based equipment and is unsuitable for on-site work due to its size and weight. Therefore development of dedicated equipment was required to enable Friction Hydro Pillar Processing to be applied to steam pipes within a power plant environment.
- Full Text:
- Date Issued: 2013
Development of conservation strategies for Alepidea Amatymbica ECKL. & ZEYH. : a rare medicinal plant in the Eastern Cape, South Africa
- Authors: Mangoale, Ramatsobane Maureen
- Date: 2017
- Subjects: Medicinal plants Plants, Cultivated
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/8667 , vital:33400
- Description: Conservation through cultivation has been recommended as a means to relieve overexploitation of medicinal plants. However, the medicinal plants users believe that plants collected from the wild are more potent than cultivated ones. Hence, there is a need for scientific documentation of the potency of cultivated medicinal plants to contribute to the development of a sustainable management strategy to conserve wild populations. This study was aimed at documenting cultivation techniques of a known medicinal plant, Alepidea amatymbica and to validate its medicinal efficacy. In order to identify overexploited medicinal plants in the study area and thus develop their conservation strategy, a survey on the trade of medicinal plants was conducted in selected towns of Amathole District Municipality of the Eastern Cape, South Africa. The survey revealed 67 plants belonging to 46 different families. Twenty-five medicinal plants were identified as overexploited and scarce and they were prioritized for conservation. Furthermore, 69.14 percent of the respondents were not willing to use cultivated medicinal plants. Lack of belief on the potency of cultivated plants and cultivation techniques were mentioned as the most significant constraints to conservation of medicinal plants. Also, the time for cultivated plants to reach maturity deterred herbal medicine practitioners from cultivating them. Alepidea amatymbica was mentioned as one of the most overexploited medicinal plants which has become scarce in the study area. This medicinal plant was therefore selected for this study. In order to develop sustainable conservation program for the species, various studies which include survey on the medicinal plants trade, cultivation, comparative micromorphology, elemental composition, toxicity, phytochemical and antioxidant activity of the wild and cultivated A. amatymbica were conducted. Cultivation of Alepidea amatymbica was conducted to determine the appropriate planting depth and rhizome fragment length for the growth of this plant. The experiment was laid out in a Complete Randomized Block Design (CRBD) with two factors in 6×3 factorial design. There were six levels of fragment length (1, 2, 3, 4, 5 and 6 cm) and three levels of burial depth (2.5, 5 and 7.5 cm). Emergence rate, number of leaves, leaf area, and plant height, number of florets, rhizome length gain, rhizome weight gain, shoot moisture and rhizome moisture were measured as growth parameters. The best overall yield in terms of plant height, shoot emergence, rhizome weight gain, number of florets and number of leaves was observed in 7.5 cm planting depth at 6 cm rhizome length. Four centimetre rhizome length had the highest leaf area of 111.9±3.5 cm2, 101.3±3.5 cm2, 105±3.5 cm2 at 2.5, 5, 7.5 cm planting depth respectively. Shorter fragment lengths showed high potential for vegetative propagation in terms of rhizome length gain at all burial depths. Scanning electron microscopy (SEM) was used to examine the foliar micro morphological characteristics while energy dispersive x-ray spectroscopy (EDXS) was used to determine the elemental composition in different parts of the wild and cultivated plants. The study revealed numerous differences between the wild and cultivated ones. These include deposition of epicuticular waxes, stomatal apparatus, helical thickening of the xylem walls, thickening of the epidermal cell layer and presence of starch grains in the parenchyma cells of the cortex. The EDXS analysis also revealed disproportionate quantities of C, O, Ca, K, Al, Mg, Si, Br and N as the major constituents in both cultivated and wild A. amatymbica specimens. The quantities of elements varied in the different parts of wild and cultivated plants. Toxicity of the methanol, water and acetone extracts of the fresh rhizome of the wild and cultivated A. amatymbica were evaluated using hatchability of cysts and lethality on the hatched cysts (nauplii) of Artemia salina. The highest hatching success was observed in the water extracts of the wild plant (46.16percent) with a MIC of 0.184 mg/ml while the cultivated plants had a hatching success of 40.83percent with MIC of 0.208 mg/ml. Highest mortality was observed in the acetone extract of the wild plants at the lethal dose of 0.191 mg/ml while the cultivated plant had a lethal dose of 0.270 mg/ml. Water extracts of both wild and cultivated plants showed similar lethal dose (LD50) of >1 mg/ml. Methanol extracts of both the wild and cultivated species exhibited almost the same level of toxicity (0.695 mg/ml and 0.628 mg/ml, respectively). Based on the Bastos criterion of toxicity indices of the lethality test, all the plant fractions demonstrated cytotoxicity effect, although the degree of their toxicity varied among the plants used. Standard spectrophotometry assays were used to quantify the phytochemical contents and to determine the antioxidant potentials of the cultivated and wild A. amatymbica. The results revealed different levels of phytochemicals with corresponding antioxidant activities. The wild extracts had higher phytochemical contents in most of the assays than cultivated extracts. Total phenol in the wild extracts ranged from 32.30±3.43 to 117.8±8.45 mg GAE/g with the acetone extracts having the highest content while the water extracts was the least. The range in the total phenol of the cultivated species was 66.46±5.29 to 98.44±6.08 mg GAE/g with the methanol extracts having the highest content while water extracts was the least. The flavonoids content ranged from 55.01±6.51 to 99.09±7.20 mg QE/mg and from 48.65±7.74 to 67.32±4.1 mg QE/mg for the wild and cultivated plants, respectively. The alkaloids contents ranged from 14.70±0.04 to 17.80±0.015 percent in the wild species while it ranged from 11.98±0.14 to 13.21±0.06 percent in the cultivated species. The wild species also showed higher antioxidant activities in most of the assays evaluated. The study revealed successful cultivation of the wild species of Alepidea amatymbica using fragments from the rhizome. The micromorphological study of both the wild and cultivated species showed minimal differences in the helical thickening of the walls in the xylem vessels and starch grain accumulation pattern. Although herbal medicine practitioners believe that cultivated species are not potent, however this study revealed some levels of phytochemicals contents and antioxidant activities which are comparable to the wild species. Cultivation is a major strategy in conserving nature and their resources. Hence, the successful domestication of A. amatymbica would help in reducing the pressure on the wild species while also meeting their medicinal demands purposes, utilisation and conserving for future generations.
- Full Text:
- Date Issued: 2017
Development of high capacity lithium-manganese-rich cathode materials xLi2MnO3•(1-x)LiMn0.5Ni0.5O2 for lithium ion batteries
- Authors: Rapulenyane, Nomasonto
- Date: 2018
- Subjects: Lithium ion batteries , Electrochemistry Lithium cells
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/34766 , vital:33442
- Description: In this study, a facile synthesis method was developed to produce layered-layered cathode materials with the formula xLi2MnO3•(1-x)LiMO2 (M= Ni and Mn) referred to as lithium-manganese-rich materials for lithium ion batteries. The prepared materials displayed high capacity ≥200 mAh/g at a current density of 20 mA/g in the voltage range of 2.0 V to 4.8 V. In particular the cathode material prepared at pH 10.0 delivered a high initial discharge capacity of 266 mAh/g at 20 mA/g current density and maintained a discharge capacity ≥220 mAh/g at 50 mA/g after 50 cycles. The synthesis method was used to further investigate the effect of lithium ratio in the layered-layered material. Li1+xMn0.6Ni0.2O2, x= 0.2, 0.25, 0.3 and 0.4 cathode materials were produced respectively. The BET surface area analysis results showed that Li1.3Mn0.6Ni0.2O2 material had comparatively higher surface area to the other cathode materials and also delivered good electrochemical results. XPS showed that the cation distribution is affected by the increase in lithium ratio, the Mn4+ percentages decreased significantly with an increase in lithium ratio. All materials peaks deconvoluted into two peaks namely Mn4+ and Mn3+, Li1.3Mn0.6Ni0.2O2 had the highest percentages of the stable Mn4+ 70.8%. Further investigation focused on the effect of the sintering temperature on the structure and the electrochemical performance of Li1+xMn0.6Ni0.2O2, x= 0.25, 0.3 and 0.4 cathode materials. X-ray diffraction showed the same patterns for all cathode materials sintered at 700˚C, 800˚C and 900˚C. Rietveld refined results however, showed that the increase in the sintering temperature, results in a decrease in the Li2MnO3 component percentage in the layered structures. Scanning electron microscopy images further proved that the particle size increases with increasing temperature. The charge–discharge tests of coin cells demonstrated that the materials sintered at 800˚C delivered higher discharge capacities above 200 mAh/g at 20 mA/g current density when compared to the materials made at the lower temperatures. Lastly the cathode material prepared at pH 10.0 was further evaluated in a cell using lithium titanate oxide Li4Ti5O12 as anode material. The cells delivered an initial discharge capacity of 213 mAh/g at 20 mA/g within a voltage range 3.3V-0.5V. The coin cells developed in this work delivered good cycling performance.
- Full Text:
- Date Issued: 2018
Development of InSb/GaSb quantum dots by MOVPE
- Authors: Ahia, Chinedu Christian
- Date: 2018
- Subjects: Semiconductors , Quantum electronics Organometallic compounds
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/23382 , vital:30537
- Description: There has been an increasing interest in the modification of semiconductor band structures through the reduction of their dimensions, which simultaneously increases the band gap energy of the material and gives rise to flexibility in device properties. Advances in III-V antimony (Sb) based semiconductor fabrication have triggered the quest for extension of the emission/absorption wavelength range of this family of compounds for optoelectronic devices operating in the mid-infrared region of the electromagnetic spectrum. An interesting material system for mid-infrared (MIR) applications is indium antimonide (InSb) quantum dots (QDs) within a gallium antimonide (GaSb) matrix. However, its band alignment and emission wavelength has been the subject of some interest and controversy over the years. This study focuses on the development of InSb/GaSb QDs by metal organic vapour phase epitaxy (MOVPE). The samples were grown on different substrates using various growth parameters in order to vary the size, density and aspect ratio of the dots. Interfacial growth interruptions while flowing various source precursors through the reactor were investigated in order to influence the chemical termination of the surface, and hence the resulting strain in the structures. The samples were characterized using photoluminescence spectroscopy, scanning probe microscopy, scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Likewise, the band alignment, energy levels, and carrier wave functions of the samples in this work were modelled theoretically using the nextnanomat software (version 3.1.0.0). A comparison of growth on two different GaSb substrates [(100) 2° off towards <111>B ± 0.1ᵒ and (111) ± 0.1ᵒ] using similar growth conditions yielded a higher dot density on the (100) substrate compared to the (111) substrate. This was attributed to the presence of terraces/atomic steps induced by the misorientation on the (100) substrate, which invariably gives rise to increased adsorption and an enhanced sticking coefficient of adatoms. Studies on the influence of a buffer layer on the morphology of uncapped dots showed that the shape and size of the dots are sensitive to the thickness of the buffer layer. In some case a corrugated buffer surface resulted, which introduced order in the arrangement of the dots, which formed preferentially inside the troughs. An increase in the V/III ratio from 1.0 to 3.0 was found to reduce the areal density of the QDs, while an analysis of the diameter histograms showed a narrowing of the size distribution with an increase in V/III ratio. The larger size distribution at low V/III was ascribed to the increase in indium species and the increased indium adatom migration length. This leads to increased dot density and nucleation sites, and thus triggers an increase in the conversion of tiny QDs into thermodynamically more suitable larger dots via coalescence. However, as the V/III ratio increased, the number of indium adatoms available for growth on the surface reduced, which automatically led to a decrease in the migration length of indium species which is unfavourable for the production of nucleation sites and to a decrease in dot density. Low growth rates were found to be beneficial for the growth of a high density (~5×1010cm-2) of QDs. Photoluminescence (PL) analysis of the capped samples at low temperature (~10 K), using an excitation power of 2 mW, showed a PL peak at ∼732 meV. Upon an increase in laser power to 120 mW, a blue shift of ∼ 8 meV was noticed. This emission typically persisted up to 60–70 K. An increase in the number of InSb QD-layers, was observed to cause an increase in the luminescence spectral line width and a long-wavelength shift of the PL lines, together with an enhancement in the strength of the PL emission. However, high resolution transmission electron microscopy (HRTEM) of the capped dots revealed the formation of an InGaSb quantum well-like structure, ∼10 nm thick, which was responsible for the PL signal mentioned above. The absence of QDs in the capped sample was attributed to inter-diffusion of Ga and In during the deposition of the cap layer, giving rise to a quantum well (QW) instead of the intended QDs. The presence of threading dislocations and stacking faults were also observed in the TEM micrographs of the samples containing multilayers, which can account for the fast quenching of the PL emission with increasing temperature from these samples. Theoretical simulations of the band alignment, wave functions and energy levels were in good agreement with the data collected from the PL spectra of the samples.
- Full Text:
- Date Issued: 2018
Development of insulin resistance in a rat model and the effects of sutherlandia frutescens as treatment and prevention
- Authors: Mackenzie, Janine
- Date: 2010
- Subjects: Metabolic syndrome , Insulin resistance -- Animal models , Obesity -- Treatment
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10340 , http://hdl.handle.net/10948/d1016216
- Description: The global number of obese people has reached pandemic proportions. High caloric diets and reduced physical exercise are to blame for this growing epidemic. Obesity has a very complex association with several other metabolic disorders, such as insulin resistance (IR), diabetes mellitus type 2 (DMT2) and cardiovascular disease. This puts a huge burden on health care systems world wide and claims many lives. Sutherlandia frutescens is a traditionally used herb, which is known to have anti-diabetic properties. However, the direct mode of action of S. frutescens still remains to be elucidated. The aim of this study was to investigate the developmental stages of high fat diet (HFD)-induced IR, to illuminate the pathogenesis of IR with a focal point on modifications in the lipid metabolism. Furthermore, the effects of S. frutescens as a treatment or prevention drug for IR and associated metabolic changes were examined. Two sets of experiments were conducted on male Wistar rats. In the first experiment rats, one week post weaning received a low fat diet (LFD), high fat diet (HFD) or HFD supplemented with S. frutescens (50mg/kg BW/d). Rats were sacrificed at week 0, 1, 2, 4, 8 and 12 in the feeding regime. In a second experiment rats were fed with a LFD or a HFD for 12 weeks and treated thereafter with S. frutescens (50mg/kg BW/d), metformin (13mg/kg BW/d) or water (control) for 28 days. Rats in the second experiment were sacrificed at week 12 to confirm IR while concurrently run rats were sacrificed after 28 days of treatment. For all the experiments rats were anaesthetized, blood was removed and rats were dissected. Plasma samples were analyzed for insulin, glucose, blood lipid parameters and cytokines. Liver, muscle and adipose tissue were analyzed for glucose uptake, total lipid content, lipid profile and fatty acid profile. It was shown that the intake of HFD caused IR and hyperinsulinaemia. The developmental stages in experiment one confirmed that an increase in plasma free fatty acids preceeded the onset of IR. Plasma and tissue lipid parameters (free fatty acid-, triglyceride- and cholesterol concentrations) showed pathological modifications in the HFD group. An ectopic accumulation of fat was observed in muscle and liver, as well as a change in membrane fatty acid profile. The results for circulating cytokines were somewhat inconclusive. Rats supplemented with S. frutescens did not develop HFD-induced IR (study one) or IR was reversed (study two). S. frutescens treatment also resulted in positive changes in plasma and tissue lipid parameters. In summary, an animal model for HFD-induced IR was established and the detrimental effect of elevated plasma FFA on glucose and lipid metabolism was observed. A novel discovery suggests that the anti-diabetic mode of action of S. frutescens is through modulation of lipid metabolism. It was also established that S. frutescens has the potential to prevent IR in vivo.
- Full Text:
- Date Issued: 2010
Development of MOVPE-grown InAsSb for barrier diode applications
- Authors: Dobson, Stephen R
- Date: 2020
- Subjects: Gallium arsenide semiconductors , Electronics
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49071 , vital:41598
- Description: In this study, layers of GaSb, InAs and InAsSb are grown by metalorganic vapour phase epitaxy and characterised. Growth is conducted using the precursors of trimethylgallium, trimethylindium, trimethylantimony and tertiarybutylarsine. Focus is then placed on the characterisation of the materials, carried out by the techniques of X-ray diffraction, photoluminescence spectroscopy, Hall measurements and photocurrent spectroscopy. It is observed that V/III ratio plays a vital role in the growth of the GaSb and InAsSb layers. Epilayers of GaSb showed best crystalline quality when a V/III ratio of 1.2 was used at a growth temperature of 600 °C and a cell pressure of 600 Torr. Resultant Hall measurements indicated p-type GaSb. The Hall carrier concentrations of the p-type GaSb samples were analyzed considering electrical neutrality conditions and found to be highly compensated with evidence of band impurity conduction at low measurement temperatures. Both the donor and acceptor concentrations were determined to be of the order of 1016 cm−3 for all samples. For low temperature (< 150 K) a monovalent acceptor concentration is calculated to have an activation energy at approximately 20 meV. At high temperature (> 150 K) a divalent acceptor is extracted with an activation energy varying between samples based on compensation in a range of 90 meV to 70 meV. Photoluminescence measurements show four peaks with recombination mechanisms linked to the native acceptor identified in literature as either the gallium antisite and/or vacant gallium site. A fifth peak observed is attributed to the longitudinal phonon of the native acceptor. InAs and InAsSb epilayer are all grown at a temperature of 600 °C and cell pressure of 600 Torr. InAs is grown at a V/III ratio of 9.5 on GaAs substrate. Photoluminescence of the InAs layer shows two distinct peaks, one of which is an extrinsic band to band recombination. The other is attributed to free electron to acceptor or a donor-acceptor pair transition. An additional weak peak is also observed which is assigned to the longitudinal phonon of the band to band. InAsSb growth was conducted under a range of V/III ratios of 4.8 to 5, with a vapour phase composition of 0.4 to 0.435. Structural analysis via X-ray diffraction showed a 6 % to 12 % solid antimony content. Photoluminescence exhibited a single broad peak for all samples, with extended band tails. Temperature and power dependant analysis of luminescence indicated a convolution of extrinsic band to tail and band to band recombinations. Hall measurements indicated the InAsSb was n-type material with an apparent measured maximum mobility at 120 K of 9.5 × 103 cm2/V.s. and a room temperature apparent mobility of 7.5 × 103 cm2/V.s. Analysis of hall results using a two-layer model calculated a true bulk mobility of the epilayer at room temperature with an increased value of 15.4 × 103 cm2/V.s. The two-layer model details the effects of the surface conduction. From photoconductivity measurements and further analysis a resultant effective lifetime, at room temperature, was found to be on same order of magnitude as that of InAs materials. Application of a single Einstein oscillator extrapolated 0 K energy gaps for two samples of solid Sb contents of 6 % and 12 %, of 354 meV and 332 meV, respectively. Finally consideration was given to the growth of aluminium containing compounds, particularly AlGaSb. Multiple phases were observed under scanning electron microscope showing growth of GaSb regions surrounded by amorphous solid aluminium and/or aluminium oxide phases. The failure of the aluminium to incorporate into the desired crystal structure is speculated to be due to impure precursor introducing oxygen into the films. Additionally, the effectiveness of the gallium precursor compared to the aluminium precursor in helping the removal of the methyl groups at the growth surface, could also promote a preference for GaSb growth.
- Full Text:
- Date Issued: 2020
Development of spunlaced nonwoven filters from PAN, PPS and PI fibres for industrial use
- Authors: Maduna, Lebo
- Date: 2019
- Subjects: Textile fibers -- Mechanical properties , Nonwoven fabrics --Technological innovations Textile fibers, Synthetic -- Mechanical properties
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32610 , vital:32266
- Description: The aim of this work was to produce filter fabrics suitable for high temperature and other conditions encountered in coal power plants using the spunlacing manufacturing technique. Polyacrylonitrile (PAN), polyphenylene sulfide (PPS) and polyimide (PI) fibres being combined suitable for this purpose, each at three aerial density of (440, 500 and 560 g/m2) and each at three water jet pressures of (60, 80 and 90 bars) were produced. The effect of changing these on the fabric air permeability, tensile strength and filtration properties were investigated and optimized. For this purpose, the Box-Behnken experimental design (BBD) was considered the best and therefore used. The PPS/PI fabrics were found to consistently have the highest air permeability, tensile strength and filtration performance, followed by the PPS fabrics and the PAN fabrics. As could be expected, an increase in area weight and water jet pressure generally resulted in a decrease in air permeability irrespective of the fabric types, this being due to the increased number of fibres and therefore greater fibre surface area and entanglement respectively. For fabric tensile strength, the effects of varying fabric area weight and water jet pressure were not so straight forward. For cross direction (CD) an increase in water jet pressure resulted in an increase tensile strength whereas in the machine direction (MD) there was a decrease when the water jet pressure was increased. The filtration efficiency and dust holding capacity of the fabrics were found to be around 96% and 211g/m2, respectively, with the exception of the PPS (500 g/m2 80 bar) fabrics. Increasing the amount of dust being fed to the fabric during each loading cycle, it caused an increase in pressure drop, as the fabrics became increasingly clogged forming a cake layer.
- Full Text:
- Date Issued: 2019
Development of Tio 2 nanostructure arrays for photonic extraction of hydrogen gas
- Authors: Suliali, Nyasha Joseph
- Date: 2020
- Subjects: Nanostructures , Nanostructured materials Hydrogen
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49314 , vital:41620
- Description: Amid the energy crisis of the 21st century, renewable energy is a thriving field of study, light harvesting materials being a central theme due to the abundance of solar energy. Nanostructured TiO2 is the most studied photocatalysis material, since the discovery of its energy harvesting properties by Fujishima and Honda in 1972. Environmentally friendly products such as hydrogen fuel, can be produced using TiO2 due to its non-toxicity, chemical stability and photocatalytic activity. The surprising aspect of this important material is that it can be prepared using cost-effective methods such as hydrothermal synthesis, solution gelation and anodic oxidation. This research focused on the three key elements required to develop TiO2 photoelectrodes i.e. the deposition of Ti films on transparent substrates, a thorough analysis of the chemistry of the anodic oxidation process and the development of the TiO2 thin films. Glass substrates that have Ti films are the base component for TiO2 photoelectrode production. Ti films with thicknesses up to 4 μm, were developed on commercial F-doped SnO2 (FTO) glass substrates using high-power impulse magnetron sputtering (HiPIMS). The sputter deposition experiments were performed in the 1 to 8 kW range at a substrate temperature of 500 °C and Ar pressure of 400 mPa. At higher powers, thicker films were deposited, resulting in increased intensity of Xray-diffraction peaks. However, on comparing the XRD patterns, the (001) peak outgrew the rest regardless of thickness of the film. The deposition process therefore favoured orientation of most of the α-Ti phase crystallites with the [001] axis perpendicular to the substrate surface. Surface roughness results were interesting, showing a non-linear dependence of the surface roughness on HiPIMS pulse energy in the 1 to 8 kW range. The surface roughness is highest at the starting deposition power of 1450 W and reduces to a minimum at 4500 W. From this minimum, it increases to its second highest value at 7900 W. From this data, the parameters required to produce Ti films of lowest surface roughness, for deposition on commercial Technistro® FTO glass, were deduced at the inflection point, where the deposition power was 4500 W. The surface roughness obtained is a critical result for the anodic production of quality TiO2 photoelectrodes, which if high, leads to uneven etching, thus irregular and inefficient photoelectrodes. Direct current magnetron sputtering was also carried out in the 1 to 5 kW range to obtain ratios of power-normalised growth rates of the Ti films. This investigation provided the Ti films on FTO glass, the transparent, conductive substrates which were used to develop TiO2 photoelectrodes. To elucidate the chemistry of anodic oxidation of Ti, a mathematical model of the anodic current density, which had not been reported at the time of its publication, was developed. The technique, a highlight of this research, is a predictive numerical computation of the instantaneous quantities of species that participate in the anodization process. From eleven chemical reactions, 14 first order ordinary differential equations were compiled using the principles of chemical reaction kinetics. The pattern, transient behaviour and response to anodization parameters of the current density signal, were successfully predicted. Strong agreement between the model and measurements was demonstrated in seven experiments. The results confirm that the current density signal is a numerical integral of the kinetics of redox reactions of water. The bulk of this research was on the development of TiO2 nanotubular arrays on Ti foil substrates and Ti films on FTO glass. TiO2 films with well-defined tubular structures were synthesised. The films were developed in anhydrous, polar organic hosts with water and etching agents in the range of 10 V to 70 V. The control of geometrical properties of the tubes such as the length, pore diameter, wall thickness, tube separation and number of nanotubes per unit area was demonstrated. Anatase only and mixed anatase-rutile phase compositions were obtained at different annealing temperatures. Nanotubes with diameters as small as 20 nm and thickness as high as 29 μm were produced. Apart from an increase in nanotube thickness, a decrease in distance between nanotubes grown in diethylene glycol was observed at longer anodization times. Studies of the effects of anodization parameters on the current density measured, morphological and crystallographic properties of the nanotube films were conducted in three main investigations. The first was the study of the effect of anodization parameters on current density. Besides the obvious increase of current density with anodic voltage, the first steady state of the growth process was found to depend on the NH4F concentration. The second investigation focused on the effect of accelerated growth of TiO2 nanotubular films. In the study, 9 μm-thick nanotube films were synthesised at twice the growth rate of a 9 μm-thick control sample. The array obtained by accelerated growth had distinguishable nanotubes, however, the morphological quality was reduced. The third investigation demonstrates the control of the number of nanotubes per unit area. By varying the etchant content, the anodic voltage and the viscosity of the electrolyte host, various distributions were obtained. The research ends with a photoelectrochemical application: measurement on photocurrents generated in a two-electrode setup. The photocurrent densities measured in the off and on conditions were 30 nA/cm2 and 2.57 μA/cm2, respectively, demonstrating photoactivity of the developed films.
- Full Text:
- Date Issued: 2020
Digital capital: a mode of bridging capital for immigrant and refugee population
- Authors: Rosendahl, Patricia
- Date: 2016
- Subjects: Social capital (Sociology) -- United States , Immigrants -- United States
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/3645 , vital:20449
- Description: The resettlement of immigrant and refugee populations poses specific challenges to new host communities. Municipalities must find resources to assist these populations in transitioning into a new culture. Immediate needs are often adequate housing, health care, and primary schooling. While this transitioning process is still in play, the search for employment begins; often at the cost of consideration of longer-term needs, such as English or other host country language acquisition and planning for long-term career goals. Theorists in the field of social capital postulate that bonding and bridging social capital offers benefits for populations adjusting to new communities. Connections to like-minded individuals or pre-existing ethnic ties (bonding social capital) can provide support important to the well-being of individuals going through difficult social adjustments while connecting with new social groups (bridging social capital) can provide new information leading to expanding opportunities. The concept of bridging social capital for immigrant and refugee populations is the subject of this research study. It is situated within the context of our digital age in which information communication technology (ICT) is the primary mode of access to information and services. For the purpose of this thesis, the capability to exploit this mode of communication is thus identified as “digital capital.” As more and more governmental, educational, and social services are distributed within a technological environment, it is necessary to examine this mode of connection to information as a form of capital which can be viewed in a similar framework to other types of social capital. Access to technology and ICTs has been considered an integral element of the Development Goals as adopted by the United Nations for the Year 2000 Millennium Goals. Though later debates have questioned how ICTs may have benefited development goals, the pervasiveness of this form of information flow continues. Within Development Studies, Sen’s theory on the Capability Approach offers a valuable opportunity of connecting digital capital to development. Just as the Capabilities Approach accommodates the diversity of human values, characteristics, and functionings, so can digital capital provide flexibility through adaptation by the users to tailor the medium to meet specific needs. It is this freedom to adjust to individual needs and goals that allows this mode of bridging capital to hold a distinct advantage for immigrants and refugees who are searching for effective links into new social networks in the job search process. The role of the community college system has been at the forefront of providing educational training and social acclimation for this population in their quest for economic self-sufficiency in the resettlement process. A greater understanding of the role that technology plays in the success of immigrant and refugee resettlement is vitally important for the well-being of communities undergoing dynamic demographic change.
- Full Text:
- Date Issued: 2016
Digital storytelling to explore HIV- and AIDS- related stigma with secondary school learners in a rural community in KwaZulu-Natal
- Authors: Mnisi, Thoko Esther
- Date: 2014
- Subjects: AIDS (Disease) in adolescence -- Social aspects -- Africa, Southern , HIV infections -- Social aspects -- Africa, Southern , Stigma (Social psychology) -- South Africa -- KwaZulu-Natal , Digital storytelling
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9576 , http://hdl.handle.net/10948/d1018717
- Description: This study explores, through digital storytelling, the experiences of HIV- and AIDS-related stigma of rural community secondary school learners. HIV- and AIDS-related stigma is seen as an impediment to a proficient response to HIV and AIDS in communities, also rural communities, and requires addressing. The rural community in which the research is undertaken is particularly hard hit by HIV and AIDS. Learners’ experiences of HIV- and AIDS related stigma could therefore inform how school and community could engage with HIV- and AIDS-related stigma and how they could address it in a constructive way. The study attempts to respond to two research questions: What can digital storytelling reveal about secondary school learners’ experiences of HIV- and AIDS-related stigma in schools in a rural community? How can digital storytelling enable secondary school learners in school in a rural community to take action to address stigma? This qualitative study is positioned within a critical paradigm, and employs a community-based participatory research strategy. Twelve Grade 8 and 9 male and female learners aged 15 to 18 years, from two secondary schools in rural Vulindlela district of KwaZulu-Natal, South Africa, who experienced, witnessed or heard about HIV- and AIDS-related stigma participated. Digital storytelling, a visual participatory method, was used to generate the data, and this was complemented by group discussion and written pieces completed by the participants in reflection sessions. The thematic analysis of the data made use of participatory analysis: the analysis of the digital stories was done by the participants while the overarching analysis was done by the researcher. This study, located in the field of the Psychology of Education, is informed by the theoretical framework of symbolic interactionism. In terms of the experienced stigma, it was found that living with HIV and AIDS and the related stigma is perceived as a ‘hardship’. The stigma is experienced on many levels: in the family, at school, and from friends and members of the community. It has an impact on the individual on an intrapersonal and interpersonal level. The young person is caught up in a vicious cycle of silent suffering since there are no reliable and trustworthy people with whom he or she can share these challenges. Some so-called traditional beliefs and customs such as not talking about sex, and practices like virginity testing, also fuel HIV- and AIDS-related stigma. The use of derogatory terms and the severe criticism of early sexual debut along with the gossiping which is used to spread the stigmatising statements further complicate the hardship experienced by young people. Digital storytelling was found to not only enable the learners’ voices to be heard but also to enable their taking charge of the stigma and thus create the space for critical participation in this research. The implications for the study are that the pervasive stigma that young people experience should be addressed at every level of the community. The stakeholders such as the families, school, educators, the King (Inkosi) and Chiefs (Indunas) of the area, relevant departments with that of Education taking the lead, must work hand-in-hand with the affected young people. Such collaboration may allow for the identification of the problem, for reflection on it, and also for the addressing of it. HIV- and AIDS-related stigma, while it has changed since the emergence of HIV, still is an issue that many HIV-positive individuals have to contend with. This stigma is, however, contextual and how the individual is stigmatised fits in with the language, meaning and thought that a community constructs around stigma. While digital storytelling enables the uncovering of particular stories of stigma that learners experience in the context of a school in a rural community, the digital storytelling in and of itself enables a change in the language, meaning and thought around stigma in its drawing on the specifics of the stigma as experienced in the community. Also, digital storytelling is about sharing stories about, and experiences of HIV- and AIDS-related stigma and how these stories can be used as part of the solution. If such stories can be told, people can spread them just as gossip is spread, but in this case such spreading would work towards positive social change. I claim that in order to confront the challenges raised by the perpetuation of stigma, efforts must involve the communities and must tap into their own experiences of perpetuating or enduring stigmatisation. Suggestions by the very same people from the community who are at the front line of perpetuating and /or suffering the stigma must be considered. This may also become one way of instantly communicating the research findings back to the community involved in the research. Using digital storytelling can ensure getting self-tailored, contextual, specific views on how HIV- and AIDS-related stigma is experienced but also how it could be addressed.
- Full Text:
- Date Issued: 2014
Dimensions of a memorable experience within a marine tourism context
- Authors: Jonas, Altouise Glowdean
- Date: 2018
- Subjects: Customer relations -- Management , Customer relations Relationship marketing Tourism -- Environmental aspects Coastal zone management -- Environmental aspects
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30540 , vital:30958
- Description: Worldwide, businesses are operating in an environment which is continuously changing, forcing them to adapt their strategies in order to remain competitive. Two changes were of particular importance to this study. Firstly, businesses are faced with an increasing demand from consumers for experiences as opposed to products and services. Secondly, consumers are demanding experiences that are not just ordinary, but are unique and memorable. As one of the largest and most diverse industries globally, tourism offers a multitude of tourist activities. Marine tourism is one of the oldest, most popular and fastest developing types of tourism globally. Marine tourism has also become popular in South Africa. This popularity might be attributed to the country’s expansive coastline and to it being home to one of the most diverse marine systems in the world. Marine tourism makes significant contributions to South Africa’s economy. More benefits can be derived from this lucrative type of tourism if attention is given to the design and provision of marine tourism experiences that go beyond average experiences, and become memorable experiences. The reason for conducting this research was to provide the South African tourism industry, and marine tourism operators in particular, with information which might assist them in designing and staging memorable experiences. Such memorable experiences could result in a competitive advantage and enable the operators to attract more customers, which in turn, will benefit the individual operators, the industry as a whole, and ultimately, the South African economy. The study focused on three marine tourism activities, namely; shark-diving, visits to marine protected areas and whale-watching. Eight dimensions, namely; Delight, Hedonism, Involvement, Knowledge, Meaningfulness, Novelty, Refreshment and Social-Interaction were identified as prospective dimensions of a memorable experience within a marine tourism context. v The study employed purposive, convenience and snowball sampling to identify potential respondents. Primary data was collected by means of an online survey and paper-based self-administered questionnaires. Four hundred and forty-four useable responses were received. The results of the empirical study showed a positive correlation between all the dimensions and memorable experience for each of the three activities and for all the activities combined. A second order factor analysis showed that the eight dimensions loaded onto two factors. The resulting factors were named as the Affective Domain (consisting of Hedonism, Refreshment, Delight and Involvement) and the Cognitive Domain (consisting of Knowledge, Social- Interaction, Meaningfulness and Novelty). A positive relationship was found between the Affective Domain and Memorable Experience and also between the Cognitive Domain and Memorable Experience. The Cognitive domain showed a stronger relationship with Memorable Experience than what the Affective Domain did, for all the activities combined. The memorability of an experience in the case of all three activities combined can, firstly, be improved by Involvement. This is closely followed by the following dimensions in the Affective Domain; Delight, Hedonism and Refreshment. Under the Cognitive Domain the factor which is most important for improving memorability of all the activities combined is Meaningfulness, followed by Knowledge, Novelty and Social-Interaction. Finally, structural equation modelling confirmed a model representing the eight experience dimensions (Delight, Hedonism, Involvement, Knowledge, Meaningfulness, Novelty, Refreshment and Social-Interaction) and identified the relationships between the dimensions and Memorable Experience. This study makes four important contributions. Firstly, it contributes to the under-researched topic of marine tourism in South Africa. Secondly, it adds to the literature on memorable tourism experiences, specifically memorable marine tourism experiences and provides a measurement instrument and framework for further research. Thirdly, the study identifies and confirms that ‘delight’ is an important dimension of a memorable marine tourism experience. vi Lastly, a model was developed which can be used by marine tourism operators to enhance their strategies, operations and facilities which will enable operators to achieve a sustainable competitive advantage.
- Full Text:
- Date Issued: 2018
Drivers and consequences of residents' satisfaction with off-campus student housing in South-South, Nigeria
- Authors: Bella-Omunagbe, Ojo Cyprain
- Date: 2015
- Subjects: Student housing -- Nigeria , Housing -- Resident satisfaction , Residence and education , Universities and colleges -- Nigeria -- Administration
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9720 , http://hdl.handle.net/10948/d1021198
- Description: The student housing system worldwide and South-South Nigeria in particular has witnessed an unprecedented transformation, such that private off-campus student housing facilities (SHFs) are now the primary source of accommodation for students in tertiary institutions. A considerable gap exists between the supply and demand for on-campus student housing and the quest to fill this gap has stimulated the creation of a significant student housing market in the areas where these tertiary institutions are located. The prospect for economic investments in the student housing sector is high and private investors are involved in the provision and management of offcampus student housing. The main consequence of this practice in South-South, Nigeria is the delivery of low-quality buildings that are not able to meet the needs and expectations of residents. SHFs that are constructed without due regard to residents needs are characterised by dissatisfaction with attributes of housing and low investment performance. The implication is that residence users are often not satisfied with the attributes of the residential environment that are provided; thus their behaviours often impose some consequences on investors gains and objectives.Therefore, understanding the dynamics among attributes that are important to students, that give the required satisfaction, and the impact of the availability or lack-of on behaviour such as loyalty, willingness to pay for attributes and word of mouth behaviour are critical to profitability. Most often, the relationship among these attributes are treated as linear and symmetrical with the assumed implication that better attributes produce improved behaviours. However, this may not always be the case. This approach is rarely addressed and is little understood in student housing studies. Therefore, the aim of this study was to identify student housing attributes that act as drivers of resident atisfaction and the consequences/effects of these drivers on student behaviour in order to determine appropriate measures that could be used to develop, maintain and upgrade student accommodation. The methodology of the study included an extensive literature review and a field study conducted to obtain the perceptions of students in seven tertiary institutions located in South-South, Nigeria. The main task was to define attributes of student housing facilities based on the symmetric and asymmetric impact of the performance of attributes on satisfaction with residence. The Kano model and importance-performance analysis (IPA) were used to establish sets of criteria that could be used to prioritise attributes that are required in student housing for optimal investor gains. Analysis of the findings lead to the conclusions that different degrees of behaviour were associated to the perception of importance that is attached to attributes by residents and the satisfaction that is derived from the use of such attributes. The implication of the conclusions is that to meet users satisfaction needs, varied improvement strategies are required for different attributes in order to maximise the use of resources for maximum gains. The recommendations for investors in SHFs include among others to segment the SHFs market based on demographic characteristics, prioritise and provide only attributes that add-value to identified groups. Emphasis should also be placed on providing attributes that are not only satisfactory, but with capacity to improve loyalty/retention, willingness to pay and positive word of mouth behaviour. It is also recommended that the local authority should improve critical attributes that are deemed to be outside the scope of the investors.
- Full Text:
- Date Issued: 2015
Dynamics of macrophytes in the East Kleinemonde, a small temporarily open/closed South Afrcan Estuary
- Authors: Riddin, Taryn
- Date: 2011
- Subjects: Estuaries -- South Africa -- East Kleinemonde
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10605 , http://hdl.handle.net/10948/1529 , Estuaries -- South Africa -- East Kleinemonde
- Description: The East Kleinemonde Estuary is one of 175 temporarily open/closed estuaries (TOCEs) that represent 70 percent of estuaries in South Africa. TOCEs are small (mostly less than 100 ha), shallow estuaries (average depth < 2 m) that respond quickly to freshwater inflow events. Their connection to the sea can be highly variable resulting in considerable changes in abiotic and biotic conditions. Mouth status depends on a balance between freshwater inflow and marine influence, which in turn affects ambient abiotic conditions. The objective of the study was to identify the abiotic variables which influence macrophyte growth and habitat availability. It was hypothesised that water level and salinity were the two main drivers of macrophyte change and macrophyte habitat would respond very rapidly, in less than a month, when habitat was available. Macrophyte habitats would also have high sediment seed reserves to ensure persistence under highly variable abiotic conditions. Macrophyte cover was monitored monthly in the East Kleinemonde Estuary along three permanent transects. The dominant habitats were submerged macrophytes, intertidal salt marsh, supratidal salt marsh, reeds and sedges. The following abiotic variables; water level, water column salinity, water temperature, Secchi depth, air temperature and rainfall were also measured between March 2006 and January 2010. Time-lag responses of the macrophytes to water level and salinity changes up to four months prior to the sampling session were also assessed. The analysis of a one year dataset highlighted only water level as a driver of change in macrophyte cover, whereas the five year dataset identified salinity as an additional important abiotic driver. This is because during September 2008 to January 2010 a series of large marine overwash events maintained high salinity (> 30 ppt) and high water level (> 1.6 m amsl) in the estuary. Water level increased by up to 0.33 m due to large volumetric changes and salinity was significantly higher in the 16 month closed euhaline phase after the breach (31 ± 0.9 ppt) compared to 21.9 ± 0.9 ppt in the closed polyhaline phase before the September 2008 breach. This increase in salinity significantly reduced the cover of the submerged macrophytes Ruppia cirrhosa and Chara vulgaris. They were replaced by macroalgae during this high salinity phase. The cover of supratidal salt marsh and reed habitats was also significantly reduced during the high water level phase, which in turn would lead to the potential for bank destabilisation and erosion. Based on the average elevation above sea level position of the macrophytes in the East Kleinemonde iv Estuary, a threshold water level was identified as 1.55 amsl. This was taken to be the height above sea level at which there was a maximum cover change for each macrophyte habitat. Above this water level emergent macrophyte habitat would mainly be inundated. This, together with 30 ppt salinity, was identified as the two thresholds for macrophyte change in the East Kleinemonde Estuary. From these thresholds and the 5 year dataset four biotic states were identified as State A: open and tidal, State B: closed with a water level below 1.55 m amsl and salinity between 18 to 30 ppt, State C: closed and water level above 1.55 m amsl and salinity between 18 to 30 ppt and State D: closed and water level above 1.55 m amsl and salinity above 30 ppt. Intertidal salt marsh, reeds and sedges were dominant during the open phase. Submerged macrophytes were dominant during the closed polyhaline state and macroalgae during the closed euhaline state. The high variability of abiotic factors common in TOCEs and the response of macrophyte habitat indicated that macrophytes were resilient to changing states provided they were of relatively short (< 3 months) duration. Macrophytes in the East Kleinemonde Estuary were found to have fast growth rates and large seed reserves in the sediment. The seed banks in the East Kleinemonde, as well as the adjacent temporarily open/closed West Kleinemonde Estuary were quantified for the first time in a South African estuary. The averaged data from both estuaries showed that Charophyte öospores represented almost 72 percent of the sexual propagules in the sediment with a mean öospore density of 31 306 ± 2 293 m-2. This was despite the Charophytes being sparsely located and only representing a maximum of 32.5 percent cover in the above ground vegetation. Historically there must have been stands of Charophytes in the East Kleinemonde Estuary, such that öospores could accumulate to such high density found in this study. The second highest seed density was for the intertidal salt marsh plant Sarcocornia tegetaria (18 percent) (7 929 ± 688 seed m-2), followed by the submerged angiosperm Ruppia cirrhosa (7 percent) (2 852 ± 327 seeds m-2). Although seed density did not differ significantly with sediment depth, seeds still occurred at 20 cm below the surface of the sediment providing a regeneration source in the event of sediment scouring during a flood event. Germination studies in the greenhouse showed that most seeds were viable and Sarcocornia tegetaria began to germinate after 3 days to a maximum of 82 percent after 91 days. Submerged species only germinated after 18 days with a low maximum germination of between 11 and 15 percent. This study has made an original contribution to the field of knowledge on macrophyte responses in a small TOCE as it showed that macrophyte habitats in the East Kleinemonde Estuary have a high natural variability in cover over time, they respond quickly after a disturbance event such as a mouth breach and there are large sediment seed reserves that remain viable from 2 to more than 5 years. This ensures habitat persistence even under unfavourable conditions, such as prolonged periods of mouth closure with high water level and flooding which causes loss of salt marsh species. Given this natural variability it is necessary to predict responses both spatially and temporally in order to manage and maintain ecological functioning in TOCEs. This study identified dominant macrophyte habitat for different abiotic states through the use of water level and salinity thresholds. In the determination of the freshwater requirements of any South African estuary freshwater inflow rates are provided for each estuary's past, present and possible future freshwater inflow scenarios. These flow data are generated by hydrological models and simulated monthly inflow volumes for a period of about 72 years are provided. For the East Kleinemonde freshwater requirement study for any year in that 70-odd year period, the number of high flow and low flow mouth breaches were predicted, as well as the closed state periods. The threshold water level of 1.55 m amsl was also used to filter past, present and future inflow monthly volumes to determine the frequency of the four abiotic states identified in this study. It was based on a water level/water volume equation calculation from a digital elevation model. Results showed that the total closed period in the present state was 83 percent, made up of 48 percent of the time in a polyhaline state (State C) and 35 percent in a euahaline state (State D). A second method was used to quantify available spatial habitat under different water level scenarios. A spatial model was written in Model Builder, an application in ArcGIS that allowed a series of processes to be built. A habitat map was overlaid with a bathymetric map and by selecting water level, available habitat areas were determined and empirical equations of water level versus available habitat were produced. These equations were then used to calculate the available habitat areas for monthly water level conditions from the freshwater requirement study for the past, present and two future inflow scenarios. Using both the threshold water level method and the spatial availability model method it was possible to assess the effect of the two future inflow scenarios on macrophyte habitat vi response. Scenario 1 had a 16 percent reduction in mean annual runoff (MAR) generating low flows for 88.6 percent of the time and a 3.5 percent reduction in flood events. In Scenario 2 there would be a 12 percent reduction in MAR with low flows occurring for 87.5 percent of the year, a 5.3 percent reduction in floods and an 11.5 percent reduction in the open mouth state. The model showed that Scenario 1 would have the highest submerged macrophyte area (12.56 ha versus 12.48 ha in Scenario 2), whereas Scenario 2 produced the largest mudflat and intertidal salt marsh area (7.11 ha versus 7.34 ha) due to lower water level in conjunction with the bathymetry of the estuary. A reduction in freshwater inflow to TOCEs either due to anthropogenic influences or natural precipitation cycles is one of the main threats to the optimum functioning of these estuaries. The results from this study and the two methods of assessing the effect of freshwater inflow scenarios on macrophytes in TOCEs can be integrated into the current freshwater inflow assessment methodology in South Africa, as well as adding to our understanding of the ecological functioning of these small, highly variable estuaries. The methods provide a quick assessment of macrophyte habitat associated with abiotic states under past, present and future inflow scenarios. All that is required to predict macrophyte habitat for different freshwater inflow scenarios (present, past and future) is a habitat map, a bathymetric map and the elevation range of macrophytes in the TOCE being assessed. This, together with the knowledge of response rates, provides invaluable information for the management of TOCEs to maintain their ecological functioning under altered freshwater inflow regimes.
- Full Text:
- Date Issued: 2011
Ecophysiology and nutrient uptake mechanisms facilitating the prolonged bloom persistence by Cyanothece sp. in Lake St Lucia, South Africa
- Authors: Du Plooy, Schalk Jacobus
- Date: 2017
- Subjects: Cyanobacterial blooms , Cyanobacteria -- Physiology , Cyanobacteria
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/7344 , vital:21324
- Description: Cyanobacterial blooms are becoming more frequent worldwide, with possible negative effects on human health. The effects of climate change and eutrophication have been associated with persistent cyanobacterial blooms becoming more frequent. Altered water characteristics, salinity in particular, influence ecosystem dynamics that may lead to conditions conducive to cyanobacterial blooms. The occurrence of an 18-month long Cyanothece sp. bloom (the longest for any cyanobacterium recorded so far worldwide and the first of the genus) from June 2009 to December 2010 in Africa’s largest estuarine lake, St Lucia, highlighted the susceptibility of ecosystems to anthropogenic alterations. This study investigated the long-term survival and physiological adaptations of Cyanothece sp. to various and dynamic environmental conditions that contributed towards its bloom persistence. The main findings are the high salinities at which Cyanothece sp. could perform important physiological processes such as N uptake, N2 fixation and photosynthesis. Nutrient uptake (both nitrogen and phosphorus) was observed over the full experimental salinity range (0-300) while N2 fixation was only observed up to a salinity of 120. Nutrient uptake rates significantly decreased at this threshold salinity of 120. Interestingly, photosystem II activity was not observed in Cyanothece sp. during this study, but photosystem I activity was robust. Salinity had a minor influence on electron transport rates by photosystem I, high temperature (> 30°C) did however increase electron transport rates. Rapid responses to hypo-osmotic shock (i.e. osmotic downshift during freshening events) by Cyanothece sp. cells also helped minimize cell rupture due to high turgor pressure. Zooplankton abundance within the St Lucia system was negatively correlated with salinity, while grazing experiments indicated that the typical estuarine zooplankton species are able to graze on Cyanothece sp. cells. Therefore, the disappearance of zooplankton at salinities above 60 must have been an important factor in the bloom persistence. Apart from the ecological factors that were at play in St Lucia during the bloom period, the persistence of the Cyanothece sp. bloom can be attributed to the robust nature of their nutrient uptake, nitrogen fixation and photosynthetic systems to maintain activity despite extreme hypersalinity levels.
- Full Text:
- Date Issued: 2017