Polymer based electrospun nanofibers as diagnostic probes for the detection of toxic metal ions in water
- Authors: Ondigo, Dezzline Adhiambo
- Date: 2013
- Subjects: Heavy metals , Nanofibers , Nanoparticles , Colorimetric analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4557 , http://hdl.handle.net/10962/d1018261
- Description: The thesis presents the development of polymer based electrospun nanofibers as diagnostic probes for the selective detection of toxic metal ions in water. Through modification of the chemical characteristics of nanofibers by pre- and post-electrospinning treatments, three different diagnostic probes were successfully developed. These were the fluorescent pyridylazo-2-naphthol-poly(acrylic acid) nanofiber probe, the colorimetric probe based on glutathione-stabilized silver/copper alloy nanoparticles and the colorimetric probe based on 2-(2’-Pyridyl)-imidazole functionalized nanofibers. The probes were characterized by Fourier transform infrared spectroscopy (FTIR), Energy dispersive x-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The fluorescent nanofiber probe was developed towards the determination of Ni²⁺. Covalently functionalized pyridylazo-2-naphthol-poly(acrylic acid) polymeric nanofibers were employed. The solid state Ni²⁺ probe exhibited a good correlation between the fluorescence intensity and nickel concentration up to 1.0 mg/mL based on the Stern-Volmer mechanism. The detection limit of the nanofiber probe was found to be 0.07 ng/mL. The versatility of the fluorescent probe was demonstrated by affording a simple, rapid and selective detection of Ni²⁺ in the presence of other competing metal ions by direct analysis without employing any sample handling steps. For the second part of the study, a simple strategy based on the in-situ synthesis of the glutathione stabilized silver/copper alloy nanoparticles (Ag/Cu alloy NPs) in nylon 6 provided a fast procedure for fabricating a colorimetric probe for the detection of Ni²⁺ in water samples. The electrospun nanofiber composites responded to Ni²⁺ ions but did not suffer any interference from the other metal ions. The effect of Ni²⁺ concentration on the nanocomposite fibers was considered and the “eye-ball” limit of detection was found to be 5.8 μg/mL. Lastly, the third probe was developed by covalently linking an imidazole derivative; 2-(2′-Pyridyl)-imidazole (PIMH) to Poly(vinylbenzyl chloride) (PVBC) and nylon 6 nanofibers by post-electrospinning treatments using a wet chemical method and graft copolymerization technique, respectively. The post-electrospinning modifications of the nanofibers were achieved without altering their fibrous morphology. The color change to red-orange in the presence of Fe²⁺ for both the grafted nylon 6 (white) and the chemically modified PVBC (yellow) nanofibers was instantaneous. The developed diagnostic probes exhibited the desired selectivity towards the targeted metal ions.
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- Date Issued: 2013
Positions on the mat : a micro-ethnographic study of teachers' and learners' co-construction of an early literacy practice
- Authors: Van der Mescht, Caroline
- Date: 2013 , 2013-06-10
- Subjects: Literacy -- Study and teaching (Primary) -- South Africa -- Eastern Cape English language -- Study and teaching (Primary) -- South Africa -- Eastern Cape English literature -- Study and teaching (Primary) -- South Africa -- Eastern Cape Education, Primary -- Research -- South Africa -- Eastern Cape Teachers -- Psychology Language and culture
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1836 , http://hdl.handle.net/10962/d1004333
- Description: Thesis embargoed until end of 2023. , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Date Issued: 2013
Postcolonial monuments and public sculpture in Zimbabwe
- Authors: Samwanda, Biggie
- Date: 2013 , 2013-10-10
- Subjects: Benhura, Dominic, 1968- -- Criticism and interpretation Madebe, Adam -- Criticism and interpretation Postcolonialism and the arts Monuments -- Zimbabwe Public sculpture -- Zimbabwe Art -- Political aspects -- Zimbabwe Collective memory in art -- Zimbabwe Old Bulawayo (Zimbabwe) National Heroes Acre (Zimbabwe)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2447 , http://hdl.handle.net/10962/d1006825
- Description: The study critically examines public art in postcolonial Zimbabwe‘s cities of Harare and Bulawayo. In a case by case approach, I analyse the National Heroes Acre and Old Bulawayo monuments, and three contemporary sculptures – Dominic Benhura‘s Leapfrog (1993) and Adam Madebe‘s Ploughman (1987) and Looking into the future (1985). I used a qualitative research methodology to collect and analyse data. My research design utilised in-depth interviews, observation, content and document analysis, and photography to gather nuanced data and these methods ensured that data collected is validated and/or triangulated. I argue that in Zimbabwe, monuments and public sculpture serve as the necessary interface of the visual, cultural and political discourse of a postcolonial nation that is constantly in transition and dialogue with the everyday realities of trying to understand and construct a national identity from a nest of sub-cultures. I further argue that monuments and public sculpture in Zimbabwe abound with political imperatives given that, as visual artefacts that interlace with ritual performance, they are conscious creations of society and are therefore constitutive of that society‘s heritage and social memory. Since independence in 1980, monuments and public sculpture have helped to open up discursive space and dialogue on national issues and myths. Such discursive spaces and dialogues, I also argue, have been particularly animated from the late 1990s to the present, a period in which the nation has engaged in self-introspection in the face of socio-political change and challenges in the continual process of imagining the Zimbabwean nation. Little research focusing on postcolonial public art in Zimbabwe has hitherto been undertaken. This study addresses gaps in this literature while also providing a spring board from which future studies may emerge. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
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- Date Issued: 2013
Representation and use of indigenous heritage constructs : implications for the quality and relevance of heritage education in post colonial southern Africa
- Authors: Zazu, Cryton
- Date: 2013
- Subjects: Albany Museum (Grahamstown, South Africa) Cultural property -- Conservation and restoration -- Research -- Africa, Southern Great Zimbabwe (Extinct city) Indigenous peoples -- Material culture -- Africa, Southern Anthropological museums and collections -- Management -- Research -- Africa, Southern Cultural property -- Management -- Research Ethnoscience -- Study and teaching -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1407 , http://hdl.handle.net/10962/d1002015
- Description: This study explores representation and use of indigenous heritage constructs with a view to identifying implications thereof for the quality and relevance of heritage education practices in post colonial southern Africa. Framed within a critical hermeneutic research paradigm under-laboured by critical realist ontology, the study was conducted using a multiple case study research design. The data collection protocol was three-phased, starting with a process of contextual profiling, within which insights were gained into discourses shaping the constitution and orientation of heritage education practices at the Albany Museum in South Africa, the Great Zimbabwe Monument in Zimbabwe and the Supa Ngwao Museum in Botswana. The second phase of data collection entailed modelling workshops in which educators engaged in discussion around the status of heritage education in post apartheid South Africa. This highlighted, through modelled lessons, some of the tensions, challenges and implications for working with notions of social transformation and inclusivity in heritage education. The third phase of data collection involved in-depth interviews. Twelve purposively selected research participants were interviewed between 2010 and 2011. Data generated across the study was processed and subjected to different levels of critical discourse analysis. Besides noting how heritage education in post colonial southern Africa is poorly framed and under-researched, this study revealed that current forms of representing indigenous heritage constructs are influenced more by socio-political discourses than the need to protect and conserve local heritage resources. The study also noted that the observed heritage education practices are oriented more towards addressing issues related to marginalisation and alienation of indigenous cultures and practices, than enhancing learners’ agency to manage and utilise local heritage resources in a more sustainable ways. Based on these findings the study recommends re-positioning heritage education within the framework of Education for Sustainable Development (ESD). ESD acknowledges both issues of social justice and the dialectical interplay between nature and culture; as such, it may allow for representation and use of indigenous heritage constructs in ways that expand current political orientations to include sustainability as an additional objective of heritage education. Given that little research focusing on heritage education has been undertaken within southern Africa, the findings of this study provide a basis upon which future research may emerge.
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- Date Issued: 2013
Rural livelihoods, forest products and poverty alleviation: the role of markets
- Authors: Mutamba, Manyewu
- Date: 2013
- Subjects: Rural development -- Zambia Rural poor -- Zambia Zambia -- Rural conditions Forest management -- Zambia Forest conservation -- Zambia Households -- Economic aspects -- Zambia Forest products -- Zambia Forests and forestry -- Zambia Non-timber forest products -- Zambia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4741 , http://hdl.handle.net/10962/d1006081
- Description: There is growing acknowledgement that forests and forest products are central to rural livelihoods, but their role in lifting households out of poverty remains contentious. This study tested the assertion by proponents of forest based poverty alleviation that changing conditions in the use and management of forests and forest products has created opportunities for poor rural households to lift themselves out of poverty. The study used detailed annual income data from various household sectors in two contrasting sites in Zambia, namely Mufulira and Kabompo districts, analyzing the relative contribution of forest income to household livelihood, the effect of household wealth status on forest use, factors driving household participation in forest product trade, and the influence of distance to urban markets on trends in the use of forest products. The study found that forest based activities play a central role in the livelihoods of households in the two study sites, contributing close to half of total household income, and dwarfing the contribution of agricultural sectors such as cropping and livestock rearing which are generally regarded as the main income sources for rural households. Forest based sectors were also found to be particularly valuable sources of household cash, often coming at critical times to meet basic needs. The findings also revealed that without the contribution of forest income, the proportion of households that would fall below the poverty line would increase sharply in both study sites. Wealthier households earned higher magnitudes of both subsistence and cash income from forest based activities than their poorer counterparts. Even the share of total household income coming from forest based activities was also higher among these better-off households, confirming that these activities are lucrative and they are improving the wealth status of households. Household participation in forest product trade was found to be influenced by demographic factors such as number of productive household members, age and the education level of the household head. Economic factors such as the level of income from wage labour, household poverty level, and ownership of key assets such as a bicycle were found to be important. Distance of homestead from the forest was also found to be an important contextual variable. The influence of urban demand on the use of forest products by rural households was significant in the study area. Although local sales played an important part as a source of cash for households, the most preferred channels for trade were linked to urban markets, either through roadside markets, middlemen or direct sales to urban buyers. The study concluded that with improved local organization and support for product development and marketing, some forest based activities provide a viable poverty alleviation option for poor rural households who otherwise have limited economic opportunities to escape poverty.
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- Date Issued: 2013
Rural women's representation and participation in local governance in the Masvingo and Mashonaland central provinces of Zimbabwe
- Authors: Kurebwa, Jeffrey
- Date: 2013
- Subjects: Local government -- Women -- Zimbabwe , Public administration -- Citizen participation -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:8313 , http://hdl.handle.net/10948/d1020085
- Description: This study focused on the representation and participation of rural women in local governance in the Masvingo and Mashonaland Central provinces of Zimbabwe. It argued that increased representation and participation of women in local governance, particularly as ward councillors and senior administrative employees, is important and should be pursued. This has the potential to change the local governance system. The research further argued that change is more likely to occur when elected women are supported by the presence of more women at the most senior administrative levels in the local governance system. The presence of more women is required if the local governance system is to become inclusive of the diversity of the people it represents, especially women. This study rejected the assumption that rural women are passive recipients of local governance since they contribute significantly in fulfilling household and community needs and interests. Through their knowledge and understanding of the construction of power relations at the local level, rural women have creatively managed to produce, reproduce and use alternative strategies which are based on their sexuality and traditional gender roles in challenging and transforming gender inequality at the local level and in improving the quality of rural women. A National Gender Management System (NGMS) that can be used to effectively promote gender equity, equality and justice in local authorities has been developed. It is desirable that the NGMS be established within the existing organisational framework of central and local governments in Zimbabwe. This should be connected to the national structures to ensure that local level activities are systematically accounted for at the national level. The NGMS recognises the strategic importance of building partnerships with social actors at all levels. Qualitative research method was used in the study. The study used both primary and secondary data in analysing the representation and participation of rural women in local governance in the two selected provinces in Zimbabwe, namely Masvingo and Mashonaland Central. Primary data was collected through in-depth interviews and survey questionnaires, while secondary data was gathered through a literature survey of relevant textbooks, newspapers, and peer-reviewed journals, reports and legislation. The research findings indicated that rural women face a number of constraints in getting access to and participating in local governance. Some of the constraints include; cultural beliefs; violence against women; lack of resources; lack of mutual support among women; domestic responsibilities; and institutional factors. The contributions of the research to the study of women in local governance are discussed. Recommendations to increase the participation of women in local governance are made. These include creating an enabling environment for women’s political empowerment, gender-responsive budgets, capacity-building programmes, establishment of gender focal points, gender management committees and teams, increasing women’s self-worth and changing perceptions by men. The study also found that decentralisation in Zimbabwe has not brought local governance closer to rural women due to the interweaving cultural, structural, physical and financial barriers local government faces in ensuring gender equality.
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- Date Issued: 2013
Sedimentology and sequence stratigraphy of the Congo and Kalahari basins of South Central Africa and their evolution during the formation and break-up of West Gondwana
- Authors: Linol, Bastien
- Date: 2013
- Subjects: Sedimentary basins -- Africa , Sedimentology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10655 , http://hdl.handle.net/10948/d1012148 , Sedimentary basins -- Africa , Sedimentology
- Description: The high elevated (ca. 1100 m) continental Kalahari Basin (KB) of southern Africa and the linked lower lying (ca. 400 m) Congo Basin (CB) of central Africa preserve in their interiors extensive sedimentary rock sequences and sediments that represent a unique record of the Phanerozoic geodynamic and climatic evolution of sub-Saharan Africa. In this thesis, field observations and new borehole data from the Democratic Republic of Congo (DRC) and Botswana are integrated with new paleontology and geochronology to present a substantially revised stratigraphy for the CB, and south-central Africa in general. This work also introduces a new multiphase model for the subsidence and uplift history of the CB, and improves correlations with the Cape-Karoo Basin (CKB) of South Africa and the Paraná Basin (PB) of south-east Brazil. Four deep boreholes, each between 2 and 4.5 km deep, drilled in the centre of the CB in the 1950’s and 1970’s are re-examined together with the colonial literature (in French) and available seismic data. This stratigraphic and basin analysis is complemented with new U-Pb dates of detrital zircons from core-samples of two of the boreholes (Samba and Dekese), as well as from samples collected during field work in the Kwango region of the south-west DRC. This work, for the first time, constrains the maximum ages and source provenances of the successions in the CB. Following the Pan African orogens (ca. 650-530 Ma), extensive sequences of red beds were deposited by regional paleocurrents to the south. These are now best preserved (1 km thick) along the West Congo, Oubanguides, and Lufilian Belts surrounding the CB. Overlying a hiatus that represents most of the early-Paleozoic, is a 1 to 3 km thick succession of easterly derived glacial, and then continental sequences of the Karoo Supergroup. This succession records the first main episode of subsidence [10-15 m/Ma], interrupted by a phase of uplift that is likely related to far-field intracontinental deformation within Gondwana supercontinent during the Variscan and Cape Fold orogenies (ca. 250-330 Ma) at its peripheries. Detrital zircons from the lower Karoo diamictites are dated at 1.85-2.05 Ga and 1.37- 1.42 Ga, and thus sourced from Paleoproterozoic (Eburnean) and mid-Mesoproterozoic (Kibaran type-I) basement rocks in Uganda and Tanzania. Zircons from all the other successions in the CB date predominantly at 950-1050 Ma and 500-800 Ma. These are derived from sediment recycling of late-Mesoproterozoic (Kibaran type-II) and late- Neoproterozoic (Pan African) sources in the Central African Republic (CAR) and Chad. A distinct unconformity across the Karoo Supergroup in the CB is overlain by 500- 1000 m Jurassic-Cretaceous sequences, here named the Congo Supergroup. During initial rapid subsidence [10-50 m/Ma], late-Jurassic (Kimmeridgian) shallow marine to continental sedimentation attests to a short transgression of proto-Indian Ocean waters into the northern CB (at 160 m above present day sea-level), succeeded by widespread deposition of aeolian dunes that extend from the southern CB to the PB in South America. The youngest zircons from these aeolian sediments in the CB date at 190 Ma and 240-290 Ma, and most likely indicate the influence of extensive silicic volcanic ash derived from the proto-Andes along the south-western margin of Gondwana. Two superimposed mid-Cretaceous (Albian-Cenomanian) lacustrine sequences in the central CB record a succeeding, slower [10-15 m/Ma], phase of basin subsidence during the opening of the South Atlantic (ca. 85-135 Ma). These Cretaceous sequences are in turn truncated by another regional peneplanation surface covered by Cenozoic (Eocene) silcretized sands and alluviums of the Kalahari Group, only 50-250 m thick in the centre of the CB. Southward, on top of the Kalahari Plateau in the central desert region of north-west Botswana, new boreholes intercepted laterally equivalent condensed lacustrine carbonates and calcretes (20-50 m thick) covered by sands. These terrestrial sequences are key archives of late-Mesozoic – Cenozoic paleo-climate changes, yet they remain stratigraphically unresolved. This new analysis of the Phanerozoic continental basins of south-central Africa and their equivalents in South America, opens a fresh continental-scale window into how West Gondwana break-up and concomitant epeirogenic uplifts of Kalahari (>2 km) and Congo (>200 m) are linked to interactions between the lithosphere and mantle geodynamics, and how these processes likely affected global climate changes.
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- Date Issued: 2013
Self-esteem, coping and the psychology of infertility
- Authors: Jordaan, Hendrina Jacoba
- Date: 2013
- Subjects: Infertility -- Psychological aspects , Self-esteem -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9959 , http://hdl.handle.net/10948/d1020055
- Description: This exploratory-descriptive study, using multiple case studies, investigated the self-esteem, coping and psychology of infertility of a sample of individuals who have received infertility treatment at a privately managed health care unit. Infertility is a complex condition associated with the inability to conceive a child, frequently manifesting itself as a result of various biological factors. A literature review indicated that being on Artificial Reproductive Technology (ART) treatment significantly increases the stress in an individual. In an attempt to gain insight into the way patients undergoing infertility treatment find the strength to complete their treatment cycles, and to endure and overcome the pressures associated therewith, in order to continue their lives – in spite of a negative treatment/pregnancy result, the researcher found it necessary to investigate the self-esteem, coping and the psychology of patients undergoing infertility treatment. An exploratory descriptive research design was used and the participants were chosen by means of a non-probability purposive sampling procedure. The participants were given a package of questionnaires to complete under the supervision of the group facilitator and researcher, prior to, as well as after the intervention. The assessment consisted of a biographical questionnaire and two standardised paper and pencil measures. The participants’ self-esteem was explored using James Battle’s (1981) Culture-Free Self-Esteem Inventory; while the coping resources were explored using Hammer and Marting’s (1988) Coping Resource Inventory (CRI). Although these data were not analysable, due to the small sample size, it was utilised in a qualitative manner to support the findings from the qualitative data. The data were also gathered from the participants via a psychological intervention programme in the format of three focus group sessions. All the qualitative results were analysed, according to Tesch’s model of content analysis. The general finding was that the period of infertility treatment is experienced as both difficult and challenging by individuals, and that there is immense healing in the sharing of one’s narrative with other infertility patients. It also surfaced that selfesteem, especially one’s feelings of worth, is most affected by a diagnosis of infertility, as well as by going through the roller coaster of the emotions associated with the treatment and monthly cycle of infertility. It was evident from the narratives told by the participants that every domain of one’s self-esteem is affected by a diagnosis of infertility, and that the biggest challenge in maintaining a positive selfesteem seemed to be in finding a balance between one’s real self and one’s ideal self. Furthermore, this study found that the challenge related to coping for the participants in this study was to present a coherent life narrative to the ‘world’, despite intense feelings of being misunderstood by others, and being faced with the discourse of infertility, as part of one’s life script. The main coping responses utilized by participants included the re-channelling of one’s focus, using denial, seeking out familial and social support, bargaining with God, and nurturing hope and faith that this journey of infertility is merely just a journey and not a destination, with the destination that of being blessed with a biological child of one’s own.
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- Date Issued: 2013
Single-end reflectometric measurements of polarization-mode dispersion in single-mode optical fibres
- Authors: Fosuhene, Samuel Kofi
- Date: 2013
- Subjects: Fiber optics , Polarization (Light) , Optical measurements
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6280 , vital:21069
- Description: In this thesis two novel single-end methods are applied to measure and characterize polarization mode dispersion in single mode optical fibres. Polarization mode dispersion (PMD) is an important factor negatively affecting the successful implementation of high speed long haul optical fibre networks operating at bit rates of 10Gb/s and above. PMD measurements are thus important for quality control during manufacturing and cabling processes. It is also useful for network operators planning to upgrade bitrates in existing networks to 10Gb/s and beyond. In an optical fibre link, sections with particularly high PMD may act to increase the entire PMD of the link. Identifying and replacing such sections can greatly reduce the PMD of the link. PMD measurements can be forward or single-end. In forward measurements, both ends of the fibre are used for input and detection. In single-end configuration, only one end of the fibre is used. For this reason, single-end measurements are more practical for the field where fibre ends are situated several kilometres apart. Single-end techniques can be implemented with a continuous wave for non-local PMD measurements (by Fresnel reflection). If a pulsed wave is used, local measurements can be achieved (by total power due to Rayleigh scattering). Two single-end schemes, one based on Fresnel reflection and the other due to Rayleigh scattering have been applied to measure non-local and local PMD of standard single mode optical fibres. For the non-local PMD measurements, the general interferometric technique (GINTY) was modified to operate in a round-trip configuration. In this configuration, the fibre was treated as a concatenation of two identical fibre segments. Three different sets of fibres were investigated, each set representing a particular mode coupling regime. For polarization maintaining fibres, (PMFs), with no mode coupling, a factor of two was found between forward and single-end measurements. For long single mode fibres in the long length regime, the factor was 1.4. For a combination of PMF and single mode fibres, a factor of 1.6 was obtained. The method which is accurate, repeatable, low cost and robust is very suitable for field applications. The second method is the polarization optical time domain reflectometric (P-OTDR) technique. This technique performs local birefringence measurements by measuring the evolution of the states of polarization (SOP). The birefringence information from such measurements was extracted and analysed to characterise four different fibres. Beat lengths and correlation lengths extracted from the P-OTDR were used to calculate the differential group delay (DGD) of the fibres. Next an expression for the root-mean-square differential group delay was derived and applied to the birefringence measurements to calculate the DGDs at a single wavelength. This method which operates at a single wavelength has a huge advantage. Firstly it is able to measure completely all the fibre characteristic parameters. Secondly it can measure mean DGD, root mean square DGD and instantaneous DGD. A plot of instantaneous DGD vs. length enables one to identify and eliminate sections with particularly high DGD. Finally since the P-OTDR system operates with a single wavelength, real time monitoring of PMD is possible via multiplexing. The results obtained are repeatable, accurate and are in good agreement with the standard Jones Matrix Eigenanalysis (JME) technique.
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- Date Issued: 2013
Standards to facilitate optimal experiences of short-term study abroad nursing students at a higher education institution
- Authors: Du Rand, Sussara Maria
- Date: 2013
- Subjects: Nursing -- Study and teaching -- United States , Transcultural nursing , Nursing -- Cross-cultural studies , Foreign study , Nursing students
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10066 , http://hdl.handle.net/10948/d1020659
- Description: Advances in technology have made globalization and internationalization a reality in the world. National borders are becoming more permeable and migration of goods, services, and health care workers takes place more readily. Higher Education Institutions (HEIs) have become competitors and vendors in the global knowledge economy and are expected to develop job seekers that are responsible and engaged global citizens and employees. Offering study abroad programmes is one of the ways that HEIs achieve this goal. It is estimated that in 2010, 4.7 million people studied abroad (OECD, 2012:360), and it is anticipated that this number will grow to 15 million by the year 2025 (Altbach & Knight, 2006:9). South Africa is emerging as a regional hub for study and research in sub-Saharan Africa (UNESCO: 2012b). Many organizations that train nurses are internationalizing their curriculum which effectively means that Schools of Nursing are seeking placement for students to study, gain insight into other cultures and practices, and to gain clinical experience in other countries. Students, the customers of the Higher Education Institutions, often pay large sums of money to undertake these study abroad programmes and therefore expect good quality learning experiences in return. The aim of this qualitative, contextual, exploratory, and descriptive study was to explore and describe the expectations and experiences of international nursing students and faculty members at a Higher Educational Institution in South Africa in order to develop standards that will enable HEIs to optimize the experiences of short-term study abroad nursing students. An in-depth contextual investigation was conducted on globalization and internationalization, as well as the higher education and health systems of three countries to understand the context of the study abroad programmes. Qualitative data was gathered from students and faculty members using focus groups and individual interviews to establish their expectations and experiences of the programme. Thematic synthesis was carried out on the contextual data and the qualitative data. Thereafter, thematic synthesis analysis was conducted using both sets of results to develop standards that can be used to optimize the experience of short-term study abroad nursing students at a HEI. A total of 35 standards were developed around the following main themes: the objectives of study abroad programmes should be stated clearly before arrival and include the expectations of the global, national, and local communities, the higher education institution and the staff and students; study abroad programmes should be managed in an ethical manner and in an enabling environment, as part of their strategic goals and plans of a HEI; students should be exposed to a variety of experiences and differences between the sending and hosting countries during their study abroad programmes; Standards to Facilitate Optimal Experiences of Short-term Study Abroad Nursing Students at a HEI; study abroad programmes should be evaluated at different intervals and levels to ensure quality of the programmes and to ensure that the objectives/outcomes are met. A limitation of the study was the sampling of the clinical mentors which did not include representatives from the overseas universities. It is recommended that the standards that were developed in this study be introduced and tested in HEIs and that more research be conducted on different levels and groups with regard to study abroad programmes in future.
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- Date Issued: 2013
Strategies to provide holistic care and support to children who are AIDS orphans living in township communities
- Authors: Frood, Sharron Louise
- Date: 2013
- Subjects: Children of AIDS patients -- Care -- South Africa , Orphans -- Care -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10064 , http://hdl.handle.net/10948/d1020655
- Description: The human immunodeficiency virus/acquired immune-deficiency syndrome pandemic (HIV/AIDS) continues to increase in prevalence worldwide, particularly in South Africa. “AIDS, (Acquired Immune Deficiency Syndrome), has devastated the social and economic fabric of African societies, made orphans of a whole generation of children and become the epicentre of the HIV/AIDS pandemic” (Fassin, 2007: 76). Like the virus itself, the AIDS crisis mutates rapidly. Children who are AIDS orphans living in South Africa, as in other African countries, suffer from recurrent psychological trauma. It starts with the illness and death of their parents and is followed by cycles of poverty, malnutrition, stigma, exploitation, sickness and often sexual abuse. The figures concerning those affected, which are staggering, offer various predictions regarding the number of orphans left in the wake of the pandemic. Between 1990 and 2003, the number of orphaned children rose from fewer than 1 million to more than 12 million in sub-Saharan Africa (UNICEF, 2005: 68). South Africa is severely affected by the AIDS pandemic, with the largest number of HIV infections in the world, a total of 5.7 million (RSA, 2010: 10), affecting approximately 3.2 million women and 280 000 children aged from 0 to14 years. There is a significant variation in HIV prevalence per province, with the Eastern Cape (EC) reportedly having an average prevalence rate of 28 percent. Hence South Africa is likely to be the country with highest percentage of children orphaned by AIDS within its population. Orphanhood is a major consequence of the AIDS pandemic in South Africa with an estimated 2.2 million AIDS-orphaned children, 11,188 per 100,000 by 2015. Most children who are AIDS orphans living in township communities live predominantly uncared for and unsupported. Therefore the purpose of this research study was to develop strategies to provide care and support to children who are AIDS orphans living in township communities. To achieve the purpose of this research study, a qualitative, exploratory, descriptive and contextual design was used by the researcher to gain insight from health and social care practitioners who render care and support to children who are AIDS orphans living in these communities. The data from in-depth interviews with the health and social care practitoners was used by the researcher to develop strategies to provide care and support to children who are AIDS orphans living in township communities. The study comprised the following four phases: Phase One: During this phase, the researcher will present an overview of the current legislative framework policies at an international, national and provincial level, regarding the the rights of children living in South Africa. Phase Two: During this phase data from two research populations were collected and analysed. As the research process of this study dealt with two groups of participants, namely in group one health care practitioners and group two comprised social workers and psychologists, who work in the township communities to provide care and support to children who are AIDS orphans living in these communities. The researcher discussed each group separately in the discussion of phase two of the study. Phase Three: Comprised the themes identified in the data gathered from the transcribed in-depth interviews, the field notes as well as the reflective journals were cross-validated to ensure trustworthiness of the data which was then organised into a conceptual framework. The conceptual framework was used to clarify the relationships of the concepts and the themes identified during the research process and also used to link the gathered data to previously established models and theories (Schneider, 2004: 133). Phase Four: The last phase of the research design, focused on the development of the “Steps of progression strategies” to provide holistic care and support to children who are AIDS orphans living in township communities. This was done making use of the themes identified during data analysis and the literature sources used throughout this research process. The evaluation criteria of Chinn and Kramer (2008: 237-248) were used to evaluate the strategies. It is therefore concluded that the researcher succeeded in achieving the purpose of this study because strategies which were understandable, clear, simple, applicable and significant to nursing practice have been developed for use by the Department of Health and Department of Social Development as well as primary health and social care practitioners to provide holistic care and support to children who are AIDS orphans living in township communities in South Africa.
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- Date Issued: 2013
Structural analysis of synthetic ferrihydrite nanoparticles and its reduction in a hydrogen atmosphere
- Authors: Masina, Colani John
- Date: 2013
- Subjects: Ferric hydroxides , Minerals -- Analysis , Nanoparticles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10555 , http://hdl.handle.net/10948/d1020796
- Description: Ferrihydrite (FHYD), a nanocrystalline material has long been described as a poorly crystalline disordered mineral mainly due to its small crystal size which is typically 2−6 𝑛𝑚. The three-dimensional structure of the mineral has long been described by a multi-phase structural model that consists of Fe3+ only in octahedral (Oh) coordination. In this model ferrihydrite is described as a mixture of two major phases (akaganeite/goethite-like f-phase and feroxyhite-like d-phase) and a minor ultradispersed nanohematite phase. This model has been recently challenged and a new, single-phase model was proposed, having a basic structural motif closely related to the Baker-Figgs δ-Keggin cluster and is isostructural with the mineral akdalaite, Al10O14(OH)2. In its ideal form, the proposed new structure of FHYD consist of 80 % Oh and 20 % tetrahedral (Td) Fe3+ polyhedra which can be adequately described by a single-domain model with the hexagonal spacegroup 𝑃63𝑚𝑐 and unit cell dimensions 𝑎=5.95 Å and 𝑐=9.06 Å. In this study, nanoparticles of 2-line FHYD (FHYD2), 2-line FHYD deposited onto SiO2 (FHYD2/SiO2) and 6-line FHYD (FHYD6) synthesised using rapid hydrolysis of Fe(NO3)3.9H2O solutions were characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Mössbauer spectroscopy (MS) as well as magnetization and magnetic susceptibility measurements. The coordination environment of iron atoms in the structure of FHYD was investigated using TEM and MS. The thermal transformation of FHYD nanoparticles was monitored through changes in the magnetization as a function of temperature and the reduction behaviour in hydrogen environment was studied using temperature programmed reduction (TPR), in-situ XRD and MS. Electron diffraction, TEM/ scanning TEM (STEM) imaging, and electron energy loss (EELS) measurements were carried out on three different microscopes viz. JEOL JEM-2100 LaB6 TEM, aberration corrected Schottky-FEG JEOL JEM-ARM200F HRTEM and cold-FEG Zeiss SESAM TEM. EELS studies were concentrated mainly on the iron 𝐿-edge of FHYD and iron oxides reference spectra with well known crystal structures. The iron oxide Fe 𝐿-edge is usually characterized by two intense sharp peaks termed “white lines”. The fine structures introduced by the crystal field effect on the 𝐿- edge contain information that is highly specific to the Fe3+ site symmetry.
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- Date Issued: 2013
Synthesis, characterisation and biological activity of 2-(methylthiomethyl)anilines, 2-(methylthio)anilines, their Schiff-base derivatives and metal(II) (Co, Ni, Cu) complexes
- Authors: Olalekan, Temitope Elizabeth
- Date: 2013
- Subjects: Aniline , Schiff bases , Ligands , Nuclear magnetic resonance spectroscopy , Chelates , X-ray crystallography , Antimalarials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4562 , http://hdl.handle.net/10962/d1020868
- Description: A series of 31 sulfur-nitrogen donor ligands and 64 metal(II) complexes have been investigated. The thiomethylated aniline ligands 2–(methylthiomethyl)aniline 2MT and 2–(methylthio)aniline 2MA were synthesized with their substituted derivatives (-Me, -MeO, -Cl, -Br, -NO2) to serve as chelating agents. These ligands behave as bidentate ligands with SN donor group with Co(II), Ni(II) and Cu(II). The Co(II) and Ni(II) complexes have the ML2Cl2 molecular formula while the Cu(II) complexes formed with MLCl2 stoichiometry where L is the bidentate ligand. The ligands and their metal(II) complexes have been characterized by elemental analysis and with spectroscopic techniques. The trend observed in the NMR spectra and IR frequencies of the thiomethylated compounds shows there is a significant difference between the 2MT and 2MA series as a result of sulfur lone pairs extending the conjugation of the aromatic ring in the case of the latter. The effect of the position and electronic nature of ring substituent on the NMR shifts of the amine protons is discussed. The 6- and 5-membered chelate complexes formed by the 2MT and 2MA ligands respectively do not show significant diversity in their spectroscopic properties. From the elemental analysis for the Co(II) and Ni(II) complexes, their compositions reveal 1:2 M:L stoichiometry with 2 chlorine atoms from the respective metal salts. In addition, the spectroscopic data are largely indicative of tetragonally distorted structures for these solid complexes. The X-ray crystallography data reveal the Cu(II) complexes exist as square pyramidal dimers and with long Cu–Cl equitorial bonds fit into the tetragonally distorted octahedral structure. The electrolytic nature of Co(II) and Cu(II) complexes in DMF were found to be similar, they behave as non electrolytes in contrast to Ni(II) complexes which are 1:1 electrolytes. The electronic spectra of these metal(II) complexes were found to be different for both their solid forms and in solutions of DMF and DMSO and this has been discussed. The thiomethylated aniline ligands possess the amine and thioether groups which are present in many known biologically active compounds, hence the biological activity of the ligands and their metal complexes were tested against three strains of bacteria and one fungus. The methoxy-substituted derivatives were found to possess better inhibitory activity and this was similarly reflected in the metal(II) complexes. The activity of the complexes can be said to be in the order, Cu(II) > Co(II) > Ni(II). The Schiff-base derivatives were prepared from the ligands and para-methoxysalicylaldehyde and their Cu(II) complexes were synthesized in order to determine their biological activity. The Schiff-base ligands were found to be less active than their parent ligands. The Cu(II) complexes are not soluble in water, DMSO or DMF, as a result and could not be evaluated for their biological activity. Based on the good results from the antimicrobial evaluation, the antiplasmodial activity of some of the Co(II), Ni(II) and Cu(II) complexes of the thiomethylated ligands against Plasmodium falciparum (FCR-3) was determined. At 50 μM concentration level, the Cu(II) complexes show activity equal or better than the prophylactic chloroquine. The Cu(II) complexes with the methoxy-substituted demonstrated exceptional activity but their Co(II) and Ni(II) analogues did not show any activity. The cytotoxicity of the active Cu(II) complexes at 50 μM concentration was determined against the breast cancer cell line (MDA-MB-231). The compounds destroyed the cancer cell in the range of 28–40%, thus showing their preferred activity against the parasitic cell instead of the cancer cell. The selectivity demonstrated by these compounds have shown them to be potential antimalarial agents and this could be further investigated.
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- Date Issued: 2013
The adaptation of the 'Clinical Outcomes in Routine Evaluation-Outcome Measure' (CORE-OM) from English into a valid Xhosa measure of distress
- Authors: Campbell, Megan Michelle
- Date: 2013 , 2013-06-06
- Subjects: Psychometrics -- Research -- South Africa Psychology -- Mathematical models -- Research -- South Africa Psychological tests -- Research -- South Africa Mental health services -- Research -- South Africa Health services accessibility -- Research -- South Africa Language disorders -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2894 , http://hdl.handle.net/10962/d1001538
- Description: In South Africa access to mental healthcare resources is restricted for a number of reasons including language barriers that prevent suitable communication between mental healthcare professionals and African language speaking South Africans. The translation of psychometric tools into African languages has been identified as one method in improving access to psychological services for African language speakers. The Clinical Outcomes in Routine Evaluation - Outcome Measure (CORE-OM) has demonstrated its clinical utility within the United Kingdom (UK) National Healthcare Service (NHS) as a standardised psychotherapy outcome measure that evaluates the degree of psychological distress individuals present with at the start of psychotherapy treatment, and the degree of change that has been effected at the termination of therapy. A measure like the CORE-OM holds valuable clinical utility for the South African context. This thesis argues that the availability of a valid Xhosa version of the CORE-OM would allow for improved access to psychotherapy resources for Xhosa speaking individuals, and allow for the evaluation of the effectiveness of psychotherapy interventions conducted in Xhosa. The CORE-OM developers have provided a translation design and set of guidelines to standardise the translation of the CORE-OM into different languages. However this thesis argues that these guidelines are incomplete. Instead International Test Commission (ITC) guidelines are recommended as a culturally sensitive method to supplement current CORE-OM translation guidelines, in order to generate a valid Xhosa measure of distress. A mixed methods approach is applied which first investigates the construct equivalence and bias of the CORE-OM English version within a South African student population sample, both qualitatively and quantitatively, in order to establish the degree of adaptation required to generate a valid Xhosa version of distress. Next the CORE-OM English version is translated into Xhosa using the five-stage translation design prescribed by the CORE System Trust, supplemented by ITC guidelines. All changes made to the CORE-OM during translation into Xhosa are documented. The CORE-OM Xhosa version is then investigated for reliability and validity. This investigation reveals low internal reliability within the subjective wellbeing domain indicating that these items are less meaningful as depictions of distress within the Xhosa language. A reduced version of the CORE-OM demonstrates strong psychometric properties as a valid Xhosa measure of distress.
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- Date Issued: 2013
The application of the Rome Statute of the International Criminal Court to illegal natural resource exploitation in the Congo conflic
- Authors: Tsabora, James
- Date: 2013 , 2013-03-27
- Subjects: International criminal law -- Congo (Democratic Republic) Criminal procedure (International law) Natural resources -- Law and legislation -- Congo (Democratic Republic)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3665 , http://hdl.handle.net/10962/d1002612
- Description: This thesis explores the phenomenon of illegal natural resource exploitation in conflict zones and the application of international criminal law, particularly the Rome Statute of the International Criminal Court to combat the roblem. Contemporary African conflicts, such as the Democratic Republic of Congo conflict explored as a case study herein, have become increasingly distinguishable by the tight connection between war and various forms of illegal natural resource exploitation, particularly targeting valuable and precious mineral resources. With their incidence being highest in Africa, wars funded by illegally exploited natural resources have gradually become one of the greatest threats to regional peace and human security on the African continent. The Congo conflict clearly demonstrated the problematic nature and impact of illegal natural resource exploitation and the widespread human, economic and political costs associated with this phenomenon. This thesis is based on the initial assumption that the quest by conflict actors to profit from war through illegal natural resource exploitation activities is at the centre of the commission of serious human rights violations as well as the complexity and longevity of African conflicts. Developments in international criminal law, culminating in the adoption of the Rome Statute and the establishment of the International Criminal Court, have given impetus to the argument that any group of conflict actors should be subjected to the individual criminal responsibility regime of this legal framework. A further underlying assumption of this thesis is therefore that international criminal law can constrain the acts and conduct defined in this thesis as illegal natural resource exploitation activities since they constitute war crimes under the Rome Statute framework. However, despite illustrating the illegal resource exploitation activities of various state and non-state actors, this thesis is confined to an application of the Rome Statute based international criminal liability regime against members of armed rebel groups involved in such acts. In exploring these issues, this work examines international criminal law institutions and the relevance of international criminal justice in addressing particular phenomena prevalent during African armed conflicts. It further provides the stage to assess the potential of international criminal law in safeguarding natural resources for the benefit of African societies perennially exposed to the depredations of natural resource financed warfare. , Microsoft� Office Word 2007 , Adobe Acrobat 9.53 Paper Capture Plug-in
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- Date Issued: 2013
The contribution of submerged macrophytes and macroalgae to nutrient cycling in the Great Brak Estuary
- Authors: Human, Lucienne Ryno Daniel
- Date: 2013
- Subjects: Nutrient cycles -- South Africa -- Great Brak Estuary , Microalgae -- South Africa -- Great Brak Estuary , Estuarine ecology -- South Africa -- Great Brak Estuary
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10364 , http://hdl.handle.net/10948/d1021102
- Description: An ecological reserve study by the Department of Water Affairs on the Great Brak Estuary stated that there was a need to determine how much nitrogen and phosphorus was flowing through the estuary as well as how effective the macroalgae were at removing N and P. The objective of this study was to investigate the physico-chemical characteristics in the estuary and the influence of these on the submerged macrophytes and macroalgae. A nutrient budget for the estuary was developed in order to quantify the contribution of the submerged macrophytes and macroalgae relative to other contributing sources. The Wolwedans Dam located 3 km upstream from the estuary has reduced the amount of freshwater flow to the estuary by as much as 56 percent. The estuary has been allocated 2 x 106 m3 per annum of freshwater (ecological reserve) that is used to breach the mouth once or twice a year in spring or summer. Even though this water has been made available it is not sufficient to flush the estuary. Reduced flushing has led to an accumulation of organic matter and degradation in the water quality. Physico-chemical measurements between September 2010 and July 2012 showed that dissolved oxygen values were generally below 6 mg l-1. The average NH4+ concentration in the estuary was 7 μM and increased with depth to 12 μM at 2 m depths. Concentrations >45 μM were found in February and April 2011 at the 5 m deep hole at 3.4 km upstream. Negative correlations between dissolved oxygen and NH4+ during November 2010, February 2011, April 2011 and July 2011 (r = -0.68; -0.67; -0.63; -0.96) indicated that remineralisation of organic matter had occurred. Soluble reactive phosphorus (SRP) followed a similar trend to the NH4+ and was generally below 1 μM in the water column for most months, and had peaks at 1.0 km and 3.4 km in the bottom water. The abundance of submerged macrophytes and macroalgae below the N2 bridge were mostly influenced by mouth state and river inflow. During the closed phase the dominant macroalga Cladophora glomerata had an area cover ranging from 3000 to 6000 m2 while Zostera capensis and Ruppia cirrhosa covered an area of 2000 to 3500 m2 and 1500 to 2900 m2, respectively. After an artificial breach in February 2011, water drained out of the estuary leaving the alga stranded on the marshes and as the flood tide entered the macroalga was once again redistributed in the lower reaches. The alga utilised the available nutrients in the water column and expanded its area cover from 35000 m2 in February 2011 to 64000 m2 in March 2011. However, after the floods in June 2011, Cladophora glomerata had been washed out of the system while the submerged macrophytes responded positively extending their area cover. By comparing the artificial breach with the natural breach, and the effect on the estuary, an important observation was highlighted. Increasing the current allocated ecological reserve, and using a larger volume of water to breach the mouth artificially, would result in better scouring of sediment and associated organic matter out of the estuary. This would enable better oxygenation of the water column, reduce remineralisation and minimise algal blooms.
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- Date Issued: 2013
The ecology and management of the large carnivore guild on Shamwari Game Reserve, Eastern Cape
- Authors: O'Brien, John William
- Date: 2013
- Subjects: Cheetah -- Behavior -- South Africa -- Shamwari Game Reserve Shamwari Game Reserve (South Africa) Carnivora -- South Africa -- Shamwari Game Reserve Wildlife conservation -- South Africa -- Shamwari Game Reserve Game reserves -- Management -- South Africa -- Shamwari Game Reserve Lion -- Behavior -- South Africa -- Shamwari Game Reserve Lion -- Ecology -- South Africa -- Shamwari Game Reserve African wild dog -- Ecology -- South Africa -- Shamwari Game Reserve Cheetah -- Ecology -- South Africa -- Shamwari Game Reserve Lion -- Food -- South Africa -- Shamwari Game Reserve Lion -- Food -- South Africa -- Shamwari Game Reserve Cheetah -- Food -- South Africa -- Shamwari Game Reserve African wild dog -- Behavior -- South Africa -- Shamwari Game Reserve African wild dog -- Food -- South Africa -- Shamwari Game Reserve Leopard -- Behavior -- South Africa -- Shamwari Game Reserve Leopard -- Ecology -- South Africa -- Shamwari Game Reserve Leopard -- Food --South Africa -- Shamwari Game Reserve
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5609 , http://hdl.handle.net/10962/d1002604
- Description: Shamwari Game Reserve was the first enclosed conservation area in the Eastern Cape Province of South Africa to reintroduce free ranging lions, cheetahs, leopards and wild dogs back into their historic range. At that time (2000 – 2001), little information was available on the ecology and behaviour of these predators in the habitats of the Eastern Cape, and management decisions were based on assumptions and unfounded comparisons with extant populations but from quite different habitats. The aim of this study was therefore to obtain a better understanding of the feeding ecology and space use of the predator guild, and the carrying capacity of Shamwari Game Reserve to enable more informed management decisions. In addition, the reserve is a photographic based tourism venture and understanding both the ecological and financial sustainability of the predator guild was important. The diets of the predators were similar to those reported in other studies; larger predators killed a greater range of prey species than did smaller predators and a small number of prey species made up the majority of the kills. The larger predators had a higher mean kill mass than the smaller species and prey selection was influenced by prey size, prey abundance and prey habitat preference, and risk associated with hunting the species. Diet was flexible and responded to natural and management induced changes in prey abundance. There was a considerable overlap in space use by the lions, cheetahs and leopards with their core areas being centred on and around the Bushmans River. Space use was driven by resource distribution and landscape attributes, and by the presence of other predators of the same or different species. The long term viability of wild dog within the reserve was explored and the results confirmed that there was neither the required space nor the ecological processes and the wild dogs were removed from the reserve. A carrying capacity of the reserve for the predator guild was determined using the Maximum Sustainable Yield method to assess the potential prey species off take and a resultant density of 3.3 to 6.6 lion female equivalent units per 10 000 ha was established. The natural carrying capacity of the reserve with respect to predators will not sustain the tourism objectives and consequently prey supplementation was necessary to maintain predator density at levels high enough to sustain tourism. Under these conditions the large predator guild is still sustainable financially although careful, responsible management is needed to provide ecological sustainability.
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- Date Issued: 2013
The impact and control of waterweeds in the Southern Mozambique Basin rivers
- Authors: Langa, Sílvia da Fátima
- Date: 2013
- Subjects: Water hyacinth -- Mozambique Water ferns -- Mozambique Water lettuce -- Mozambique Salvinia molesta -- Mozambique Aquatic weeds -- Mozambique Invasive plants -- Mozambique Aquatic weeds -- Control -- Mozambique Invasive plants -- Control -- Mozambique Aquatic weeds -- Biological control -- Mozambique Invasive plants -- Biological control -- Mozambique Aquatic resources -- Management -- Mozambique Beetles -- Mozambique Insects as biological pest control agents -- Mozambique
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5587 , http://hdl.handle.net/10962/d1001905
- Description: In Mozambique, establishment of aquatic weeds has been enhanced through the increased enrichment of water bodies by nutrient runoffs from human and agricultural wastes that lead to an increase in nitrate and phosphate in the water. The aquatic weeds, water hyacinth (Eichhornia crassipes), red water fern ( Azolla microphylla), water lettuce (Pistia stratiotes) and salvinia (Salvinia molesta) were found in most watercourses in Mozambique and are becoming aggressive in some watercourses, especially in the Umbeluzi and Incomati rivers. Farmers and people living along the rivers are aware of the negative impact of the water weeds because the large mats of weeds cause loss of shoreline and navigability along the rivers. Other commonly perceived effects of aquatic invasive plants in Mozambique rivers include: reduced navigable surface area; difficulties for fishermen, which reduces income; increased prevalence of insects and insect-borne disease, and decreased aesthetic value. The methods currently used for the control and management of the aquatic weeds are mechanical and manual control. Both methods are costly, time consuming, and only provide a short-term solution to the problem. The study found that the weevils Neochetina eichhorniae and N. bruchi were effective biological control agents in the study area but their impact is too gradual compared to the aggressive proliferation of water hyacinth. The one year lab-experiment clearly demonstrated that the water lettuce weed had a significant impact on the recruitment of macro-invertebrates to the artificial substrates, and water lettuce contributed to the reduction of oxygen in the water and consequent reduction of macro-invertebrate abundance and diversity. The biodiversity recovered at the same time in the pools containing water lettuce controlled by N. affinis and water lettuce controlled by herbicide, but richness and diversity of macro-invertebrates was higher in the water lettuce controlled by N affinis during the first sampling occasion compared to the water lettuce in pools controlled by herbicide, where macro-invertebrates increased only when DO levels recovered after water lettuce mat decay. The number of taxa recorded in this study is an indication of the significance of macro-invertebrates in an aquatic environment. This therefore emphasizes the need for more research efforts into macrophyte and macro-invertebrate associations in the aquatic system to better understand the implications of habitat modification arising from human activities. It will also enable us to be better equipped with a more appropriate ecological understanding for aquatic resources management.
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- Date Issued: 2013
The influence of overwash and breaching events on the spatial and temporal patterns in ichthyofauna community composition in a temporarily open/closed southern African estuary
- Authors: Tweddle, Gavin Paul
- Date: 2013
- Subjects: Estuarine fishes -- Africa, Southern Marine fishes -- Africa, Southern Fishes -- Breeding -- Africa, Southern Fishes -- Effect of habitat modification on -- Africa, Southern Fishes -- Spawning -- Africa, Southern Gobiidae -- Africa, Southern Estuaries -- Africa, Southern Estuarine ecology -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5610 , http://hdl.handle.net/10962/d1002957
- Description: This study assessed the importance of overwash and breaching events on the ichthyofaunal community structure in the medium-sized temporarily open/closed Mpekweni Estuary located on the southeast coastline of southern Africa. The fish in the littoral zone of the estuary were sampled using a 5m seine net while the channel region was sampled using two nets, a smaller meshed 30m seine net to target the estuarine spawning species and the juvenile estuarine-dependant marine spawners, and a larger meshed 50m seine net to target the larger marine and freshwater spawning species. Intensive monthly sampling over two years provided data on selected physico-chemical and biological parameters. During the two year sampling period from November 2005 to October 2007 the estuary breached in late July 2006 and remained open till the sandbar re-formed across the mouth in late December 2006. Thus, sampling encompassed three open/closed phases 1) initial closed period, 2) open period and 3) re-closed period after the berm was re-formed. The open period was divided into two phases 1) the out-flow phase and 2) the tidal phase. A total of 36 fish species representing 19 families were sampled using the various seine nets employed during the investigation. In the littoral zone, the estuarine spawners (Estuarine Utilisation Category, [EUC] I), mainly the Gobiidae, Glossogobius callidus, dominated the samples numerically and by biomass. The smaller estuarine spawning species sampled in the channel were numerically dominated by Gilchristella aestuaria in conjunction with two other EUC I species, Atherina breviceps and G. callidus. The estuarine-dependant marine spawners (EUC II), however, dominated the ichthyofaunal biomass of the channel. The abundance and biomass of the larger species targeted were dominated by estuarine-dependant marine spawning species (EUC II), principally Rhabdosargus holubi. During the closed periods of the estuary, total fish abundance and biomass displayed weak seasonal patterns. The breaching event and subsequent open period was associated with a decrease in the total abundances of fish in the littoral zone and channel of the estuary, reflecting the out-flow of estuarine biomass-rich water into the marine environment. The breaching event coincided with a shift in the community composition of the ichthyofauna, reflecting the recruitment of marine spawning species into the estuary. Numerical analysis identified two distinct spatial fish communities within the estuary, a community associated with the mouth region and one comprising the rest of the estuary. The absence of any further spatial patterns in the ichthyofaunal community structure within the Mpekweni Estuary appear to be ascribed to the virtual absence of horizontal patterns in physico-chemical and biological parameters recorded in the system. Cohort analyses were employed to determine possible recruitment events for selected estuarine and marine spawning species. The estuarine spawning species displayed continuous recruitment patterns throughout the study, which appeared to be unaffected by the breaching event. Conversely, the larger marine spawning species displayed multiple cohorts, indicating non-continuous recruitment. Subsequent retrospective analysis of cohorts for the different species identified summer recruitment peaks that coincided with the breaching event and open period. Minor recruitment of marine spawning species also occurred during overwash events. The recruitment of ichthyofauna into the estuary was quantified during three distinct hydrological events: overwash, out-flow phase immediately after breaching and tidal phase during the period when the mouth was open. Estimates of fish recruitment were highest during the outflow phase immediately after the estuary breached and declined as the estuary became tidally inundated with marine water. Although not as high as the outflow and tidal phases, recruitment was evident during overwash events. Results of the current study highlight the importance of both breaching and overwashing events in structuring the ichthyofaunal community composition in a medium-sized southern African temporarily open/closed estuary. These results are broadly in agreement with similar studies conducted both locally and in other regions of the world.
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- Date Issued: 2013
The restoration of an alien-invaded riparian zone in grassy fynbos, South Africa
- Authors: Fourie, Saskia
- Date: 2013
- Subjects: Fynbos ecology -- South Africa Riparian ecology -- South Africa Riparian restoration -- South Africa Alien plants -- South Africa Invasive plants -- South Africa Endemic plants -- South Africa Plants -- Effect of fires on -- South Africa Soil seed banks -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4733 , http://hdl.handle.net/10962/d1003840
- Description: The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.
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- Date Issued: 2013