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Development of tourism diploma in IsiXhosa-speaking students' academic literacies : a multilingual intervention

  • Authors: Batyi, Thokozile Thelma
  • Date: 2014
  • Subjects: Education, Bilingual -- South Africa -- Port Elizabeth , Language and languages -- Study and teaching -- South Africa -- Port Elizabeth , Education -- Study and teaching (Higher) -- South Africa -- Port Elizabeth , Multilingual communication -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:8369 , http://hdl.handle.net/10948/d1020194
  • Description: In this study, it is argued that a bi/multilingual instruction is extremely beneficial for bi/multilingual students in higher education in South Africa. Since the adoption of democracy in 1994, cultural and linguistic diversity has become the norm in classrooms at Nelson Mandela Metropolitan University in Port Elizabeth. The testing of bi/multilingual strategies in this study (i.e. translation and development of multilingual glossaries; code-switching by tutor and students during teaching and learning; code-meshing by students online; and reading, speaking and writing bilingually), is an attempt to pedagogically adapt the curriculum to students’ needs. The data was collected from students in their Tourism Communication tutorial. The study was conducted in order to demonstrate that students benefit from bilingual pedagogies, which mobilise isiXhosa and English as languages of learning. Data was collected from tests, a questionnaire and interview, summaries, online discussions, written assignments and reflective journals in order to determine to what extent students’ performance was enhanced by bilingual tuition.
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  • Date Issued: 2014

The thermodynamics of binary liquid mixtures of compounds containing multiple bonds.

  • Authors: Baxter, Rodney Charles
  • Date: 1989
  • Subjects: Solution (Chemistry)
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:4531 , http://hdl.handle.net/10962/d1016079
  • Description: Excess thermodynamic properties have been determined for several binary liquid mixtures with the aim of testing various thermodynamic theories and postulates. Excess molar enthalpies, HEm, have been determined using an LKB flow microcalorimeter and excess molar volumes, VEm, have been determined using an Anton Paar vibrating tube densitometer. The activity coefficients at infinite dilution ƴ∞₁₃, have been determined using an atmospheric pressure gas-liquid chromatograph. The excess molar enthalpies and the excess molar volumes have been measured at 298.15 K for systems involving the bicyclic compounds decahydronaphthalene (decalin), 1,2,3,4-tetrahydronaphthalene (tetralin), bicyclohexyl, or cyclohexylbenzene mixed with 1- hexene, 1-hexyne, 1-heptene, 1-heptyne, cyclohexene, 1,3-cyclohexadiene, 1,4- cyclohexadiene, or benzene. These excess properties have also been measured for systems where the bicyclic compound has been replaced with benzene, cyclohexane or n-hexane. The results show defmite trends related to the size, shape, and the degree of unsaturation of the component molecules. The Flory theory has been used to predict excess molar enthalpies and excess molar volumes for {(a bicyclic compound or benzene or cyclohexane or n-hexane) +(an n-alkane or a 1-alkene or a 1-alkyne or a cycloalkane or cyclohexene or a cycloalkadiene or benzene)}. The one parameter equations offer reasonably good correlations between the predicted and the experimental results. More insight into the origins of the contnbutions to the excess thermodynamic properties for these systems has been gained by considering the approximate equations of Patterson and co-workers, which separate the interactional and the free volume contributions to the excess molar enthalpy and the excess molar volume. The one parameter equations have adequately rationalized a good deal of the observed behaviour for HEm and VEm. The theory of Liebermann and co-workers, which does not employ any adjustable parameters, has not been as successful at predicting the excess thermodynamic properties for the above systems. The activity coefficients at infinite dilution have been measured at 278.15 K, 288.15 K and 298.15 K for n-bexane, 1-bexene, 1-hexyne, n-heptane, 1-heptene, 1-heptyne, cyclohexane, cyclohexene, 1,3-cyclohexadiene, 1,4-cyclohexadiene, and benzene, in decalin, tetralin, bicyclohexyl, and cyclohexylbenzene. Solvent losses from the column have been accounted for by an extrapolation procedure. The activity coefficient results together with the HEm and VEm values have been used to calculate the partial molar excess thermodynamic properties of mixing at infinite dilution. The partial molar excess properties at infinite dilution for decalin mixtures are similar to those for bicyclohexyl mixtures. There is also a similarity between the properties of the tetralin mixtures and the cyclohexylbenzene mixtures. The cycloalkadienes, benzene and the 1-alkynes exhibit a strong dissociation effect on being mixed with the saturated solvents, decalin and bicyclohexyl, but associate strongly with tetralin and with cyclohexylbenzene. The Flory theory bas been used to predict activity coefficients at infinite dilution from the experimentally determined HEm results for { (n-bexane or 1-hexene or 1-hexyne or naheptane or 1-heptene or 1-beptyne) + (a bicyclic compound)}. The theory is much better at predicting values for mixtures where both components are either saturated molecules or are unsaturated molecules than for {saturated + unsaturated} mixtures.
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  • Date Issued: 1989

Servant leadership: antecedent to Quality of Worklife of customer service frontline employees

  • Authors: Bedser, Mark Bernard
  • Date: 2018
  • Subjects: Call center agents Servant leadership Customer Service -- Quality control Employee morale Job satisfaction Quality of work life
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/62144 , vital:28132
  • Description: Contact Centre agents operate in closely monitored and highly controlled environments and their work consists of solving service requests or assisting customers with information on products or services. Consequently their work involves a great deal of emotional labour and stress. It is not surprising then, that the working environment of the Contact Centre is reported to have a negative impact on the levels of Quality of Worklife of Contact Centre agents, and that in the Contact Centre context, it is likely that low levels of Quality of Worklife exist. It is argued that it is important for organisations to be particularly aware of the Quality of Worklife perceptions of their employees should they want to address Quality of Worklife levels and benefit from the positive consequences of higher levels of the construct. Numerous variables are reported to play either an antecedent, moderating, mediating, or consequential role in relation to the Quality of Worklife construct. A systems model of Quality of Worklife is developed, which illustrates the inter-relationships of these variables and how they affect and are affected by the Quality of Worklife construct. It is argued that leadership is an important antecedent to Quality of Worklife, and this is the antecedent of interest in this study. It is proposed that it is not just any leadership that will contribute to an improved Quality of Worklife, particularly within a challenging context such as the Contact Centre environment. Rather, it is suggested that certain qualities of leaders will have a greater influence on Quality of Worklife. For example, leaders who focus on relationships and are caring - characteristics associated with servant leaders - are deemed more suitable for the Contact Centre context. The research also proposes that there are close associations between Servant Leadership and Trust, which in turn has the potential to affect Quality of Worklife positively. It is argued, therefore, that Trust mediates the relationship between Servant Leadership and Quality of Worklife in the customer service frontline context. While there is a broad base of literature available on servant leadership that focuses on the senior or executive level of leadership, Van Dierendonck and Nuijten (2011) have argued that it is also relevant at the middle level of management and have validated an eight dimensional measure of servant leadership that is suitable for this management level. The Van Laar, Edwards and Easton (2007) Quality of Worklife model is also argued to be an appropriate model and measure of the Quality of Worklife construct, due to the robustness of the instrument design and the appropriateness of its underlying theory to the context of this research. Research has shown that leadership can have a significant relationship with Quality of Worklife. Moreover, a review of the literature on servant leadership reveals that trust, satisfaction, general well-being, and commitment to their jobs increases when employees are exposed to leadership behaviours associated with servant leadership. There is however, no evidence in the literature of any investigation of the relationship between Servant Leadership and Quality of Worklife, or of research investigating the partial mediating effects of Trust between these two constructs. Research was conducted to test this relationship. A survey questionnaire was administered amongst a sample of 555 Contact Centre agents, who were employed in eight different organisations. Confirmatory factor analysis procedures were conducted in STATA (V15.0), to test and validate the factor structure of Servant Leadership and Quality of Worklife models. The research also produced a Servant Leadership, Trust and Quality of Worklife structural equation model that supported the hypotheses of the relationships between the constructs. Mediation analysis confirmed Trust’s role as a mediator between Servant Leadership and Quality of Worklife. The structural equation model confirmed that synergies between Servant Leadership, Trust and Quality of Worklife exist, and that Trust partially mediates the relationship between Servant Leadership and Quality of Worklife. It is therefore argued that an increase in Servant Leadership behaviour by the manager or supervisor of frontline staff has a positive association with increases of Trust, as well as positive associations with Quality of Worklife experienced by employees in the frontline context. Moreover, it is also posited that the relationship between Servant Leadership and Quality of Worklife is partially mediated by Trust of the supervisor. The implications of these results are discussed, and recommendations made for management practice and further research.
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  • Date Issued: 2018

Enhanced visualisation techniques to support access to personal information across multiple devices

  • Authors: Beets, Simone Yvonne
  • Date: 2014
  • Subjects: Information visualisation , Database management , Web services , Personal information management
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:10500 , http://hdl.handle.net/10948/d1021136
  • Description: The increasing number of devices owned by a single user makes it increasingly difficult to access, organise and visualise personal information (PI), i.e. documents and media, across these devices. The primary method that is currently used to organise and visualise PI is the hierarchical folder structure, which is a familiar and widely used means to manage PI. However, this hierarchy does not effectively support personal information management (PIM) across multiple devices. Current solutions, such as the Personal Information Dashboard and Stuff I’ve Seen, do not support PIM across multiple devices. Alternative PIM tools, such as Dropbox and TeamViewer, attempt to provide a means of accessing PI across multiple devices, but these solutions also suffer from several limitations. The aim of this research was to investigate to what extent enhanced information visualisation (IV) techniques could be used to support accessing PI across multiple devices. An interview study was conducted to identify how PI is currently managed across multiple devices. This interview study further motivated the need for a tool to support visualising PI across multiple devices and identified requirements for such an IV tool. Several suitable IV techniques were selected and enhanced to support PIM across multiple devices. These techniques comprised an Overview using a nested circles layout, a Tag Cloud and a Partition Layout, which used a novel set-based technique. A prototype, called MyPSI, was designed and implemented incorporating these enhanced IV techniques. The requirements and design of the MyPSI prototype were validated using a conceptual walkthrough. The design of the MyPSI prototype was initially implemented for a desktop or laptop device with mouse-based interaction. A sample personal space of information (PSI) was used to evaluate the prototype in a controlled user study. The user study was used to identify any usability problems with the MyPSI prototype. The results were highly positive and the participants agreed that such a tool could be useful in future. No major problems were identified with the prototype. The MyPSI prototype was then implemented on a mobile device, specifically an Android tablet device, using a similar design, but supporting touch-based interaction. Users were allowed to upload their own PSI using Dropbox, which was visualised by the MyPSI prototype. A field study was conducted following the Multi-dimensional In-depth Long-term Case Studies approach specifically designed for IV evaluation. The field study was conducted over a two-week period, evaluating both the desktop and mobile versions of the MyPSI prototype. Both versions received positive results, but the desktop version was slightly preferred over the mobile version, mainly due to familiarity and problems experienced with the mobile implementation. Design recommendations were derived to inform future designs of IV tools to support accessing PI across multiple devices. This research has shown that IV techniques can be enhanced to effectively support accessing PI across multiple devices. Future work will involve customising the MyPSI prototype for mobile phones and supporting additional platforms.
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  • Date Issued: 2014

Conditions enabling or constraining the exercise of agency among new academics in higher education, conducive to the social inclusion of students

  • Authors: Behari-Leak, Kasturi
  • Date: 2015
  • Subjects: Social integration -- South Africa , Students -- South Africa -- Social conditions , Educational change -- South Africa , College teachers -- South Africa , Education, Higher -- South Africa , Critical realism , Social realism , Agent (Philosophy)
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1333 , http://hdl.handle.net/10962/d1020295
  • Description: This study, which is part of a National Research Foundation project on Social Inclusion in Higher Education (HE), focuses on the exercise of agency among new academics, conducive to the social inclusion of students. Transitioning from varied entry points into higher education, new academics face numerous challenges as they embed themselves in disciplinary and institutional contexts. Given the complexity and contested nature of the current higher education landscape, new academics are especially vulnerable. Using Roy Bhaskar’s critical realism as meta-theoretical framing and Margaret Archer’s social realist theory, with its methodological focus on analytical dualism and morphogenesis, this study offers a social realist account of how new academics engage with enabling and constraining conditions at institutional, faculty, departmental and classroom levels. Through an analysis of six individual narratives of mediation, this study explicates and exemplifies the range of agential choices exercised by new academics to mediate their contested spaces. A nuanced social and critical account of the material, ideational and agential conditions in HE shows that the courses of action taken by these new academics are driven through their concerns, commitments and projects in higher education. Yet, despite the university’s espousal of embracing change, the current induction and transition of new academics is inadequate to the task of transformation in higher education. Systemic conditions in HE, conducive to critical agency and social justice, are not enabling. Bhaskar’s Seven Scalar Being, used as an analytical frame and heuristic, guides the cross-case analysis of the six narratives across seven levels of ontology. The findings highlight that, despite difficult contextual influences, the positive exercise of agency is a marked feature of new participants in HE in this study. This has immediate implications for ways in which professional and academic development, and disciplinary and departmental programmes, could create and sustain conducive conditions for the professionalisation of new academics through more sensitised practices. Using alternative research methods such as photovoice to generate its data, this doctoral study proposes that new research methodologies, located in the third space, are needed now more than ever in HE sociological research, to recognise the researcher and the research participants as independent, autonomous and causally efficacious beings. To this end, this study includes a Chapter Zero, which captures the narrative of the doctoral scholar as researcher, who, shaped and influenced by established doctoral practices and traditions in the field, exercises her own doctoral agency in particular ways.
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  • Date Issued: 2015

The antifungal activity of an aqueous Tulbaghia violacea plant extract against Aspergillus flavus

  • Authors: Belewa, Xoliswa Vuyokazi
  • Date: 2015
  • Subjects: Medicinal plants , Antifungal agents , Fungi -- Biotechnology
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/5858 , vital:21001
  • Description: Phytochemical analysis of both HEA1 and the crude plant extract showed the presence of phenolics, tannins and saponins. Saponins were the predominant secondary metabolites and were mostly abundant in the plant extract and to a lesser extent in the active compound. Steroidal saponins, tannins and phenolics were also detected in the plant extract, but only the phenolics were detected in the active compound. The results of the phytochemical analysis showed that those compounds that were not present in the active compound could be removed from the crude extract during the TLC purification process. Investigation on the mechanism of action of the crude plant extract on the sterol production by A. flavus showed that the plant extract affected ergosterol biosynthesis by causing an accumulation of oxidosqualene in the ergosterol biosynthetic pathway resulting in a decline in ergosterol production. An oscillatory response in lanosterol production was observed in the presence of the plant extract, which may be an adaptation mechanism of A. flavus to unfavourable conditions and compensation for the loss of enzyme activity which may have occurred as a result of the accumulation of oxidosqualene. The antifungal activity of the plant extract on ergosterol production by A. flavus may also be due to saponins which target the cell membrane and ergosterol production in fungi. The effect of the plant extract on the fungal cell wall of A. flavus also showed that the plant extract caused a decline in β-(1, 3) glucan production by inhibiting β-glucan synthase. The plant extract also affected the chitin synthesis pathway of A. flavus, by causing a decline in chitin production, which was due to the inhibition of chitin synthase. Investigation of chitinase production using 4MU substrates showed that the plant extract caused an accumulation of chitobioses, by activating chitobiosidases and endochitinases. A decline in N-acetylglucosaminidase activity in the presence of the plant extract was observed and this prevented the formation of N-acetylglucosamine. The accumulation of chitobiosidase and endochitinase may be as a result of autolysis that may be triggered by A. flavus as a survival mechanism in the presence of the plant extract and as a compensatory mechanism for the loss of β-glucans and chitin. The antifungal effect of the plant extract on various components of the cell wall of A. flavus, makes T. violacea aqueous plant extract an ideal chemotherapeutic agent against both human and plant pathogens of Aspergillus. The broad spectrum of antifungal activity of T. violacea against A. flavus also eliminates any chances of the fungus developing resistance towards it and would make it a candidate for use as a potential antifungal agent. Further identification and possible chemical synthesis is needed to shed light on the safety and efficacy of the active compound for further development as a chemotherapeutic agent.
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  • Date Issued: 2015

Understanding the learning that occurs through up-skilling opportunities and practices in the marine sector of South Africa

  • Authors: Bell, Caroline Margaret
  • Date: 2019
  • Subjects: Biodiversity conservation -- South Africa , Human capital -- South Africa , Marine sciences -- Employees -- South Africa -- Training of , Biodiversity Human Capital Development Strategy (South Africa)
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/93966 , vital:30977
  • Description: South Africa is characterised by cultural and biological diversity which constitute a unique context in which to conduct educational research, such as this doctoral study looking at human capital development in the marine biodiversity context. The drive for transformation in the country is also a major factor to consider when researching any sector of the economy, in this case, the biodiversity sector. The biodiversity sector includes organisations involved in biodiversity conservation, research and management. Previous research in the sector has found a clear need for well-thought out workplace skills plans within conservation and research organisations. The national Biodiversity Human Capital Development Strategy that was produced in 2010 by the South African National Biodiversity Institute outlines how all the organisations involved in the biodiversity sector of South Africa need to participate in strengthening the sector through a range of human capital development strategies. This includes extending the existing human capacity of managers and scientists who are already in the workplace, i.e. up-skilling. In particular, ‘scarce’ skills, as identified by the national Environmental Sector Skills Plan need further attention and development. The scarce skills relevant to this study are: protected area managers; ecosystem managers and post-graduate researchers, hence the focus on managers and scientists in this research. The marine sector falls within the biodiversity sector and it faces multiple conservation challenges which are complex and it is therefore essential to have skilled and capable managers and scientists in place. By investigating the up-skilling opportunities and practices available to these marine professionals, the goal is to understand if and how learning takes place in the marine sector of South Africa. The main research question of this study is: How do up-skilling opportunities and practices enable learning in, through and for the workplace, by marine professionals? In addition, three sub-questions provide finer details and introduce the central concepts of the research: I. What up-skilling opportunities and professional practices exist in or for, marine research and conservation organisations and how are they constituted and enacted via practice-based sayings, doings and relatings? II. How do the individuals learn and exercise their agency within the socio-material realities of the marine scientific and management context, through making use of up-skilling opportunities that are both formal (e.g. course based) and informal? III. How do generative mechanisms shape the constitution and enactment of up-skilling opportunities and practices, and the learning and agency of marine professionals (scientists and managers)? The theoretical work of this study consisted of, first, considering sensitising concepts which included: defining skill and knowledge; considering what an up-skilling opportunity might look like; workplace learning (both formal and informal learning); professional practices, lifelong learning or adult education, and agency in the workplace. Critical realism was then employed as the meta-theory that underlabours this research, while the substantive theories used for analysis purposes were socio-materialism and practice theory. Of course, critical realism is a socio-material theory itself, and Bhaskar’s four-planar social being or Social Cube was used to interpret and synthesise the findings in the data chapters. The methodological framework of this study explores the implications of critical realism for research design and analysis and includes a contextual profiling phase, semi-structured interviews, analysis of documents and peer-reviewed papers, as well as observations. There are nine case studies that form the focus of this research and in total 18 research participants were involved. Data analysis included abduction and retroduction as the primary modes of inference and the main analytical tool was the framework of practice architectures where I took the ‘sayings’, ‘doings’ and ‘relatings’ as themes. Further themes were developed from the other relevant theories used in this study; hence socio-materialism, learning, agency, and formal and informal opportunities, were also used as themes when coding the data. Issues around validity, ethics and reflexivity are key elements of the research design and were carefully considered throughout the research process. The principal data chapters are structured in such a way that each sub-question is considered and ultimately the findings are presented in the form of generative mechanisms which included: the politics of social transformation and knowledge as a driving force of up-skilling; the influence of individual disposition and passion or will; the importance of the socio-material realities and realistic expectations; and how relationality is critical for the marine sector. Agency was a cross-cutting theme in all the discussions around learning, practices and the role of the material, and was highly influential on the mechanisms that have been described in this study. The experiences, events and mechanisms that were uncovered in this research provide insight into the forms of learning as these relate to up-skilling that occur in the marine sector, as well as the complex relationships between formal and informal learning. The professional practices that occur in the everyday working lives of the marine professionals were shown to be an integral part of the learning process, while formal, certified opportunities are important for strengthening the field and building conservation competence in the country. By uncovering the deeper structures and mechanisms that have power and causal efficacy when it comes to up-skilling opportunities, learning and professional practices, this study has contributed to the field of environmental education as it shows how up-skilling processes operate in complex formations that involve formal and informal learning processes in workplaces. The study also offers a more nuanced view of the relational objects in this field, such as up-skilling and workplace learning, via the inclusion of a socio-material analysis. Through a theoretical and methodological framework that focused on the material using the tools of practice theory and Bhaskar’s depth ontology and four-planar social being (to synthesise and interpret the findings from a critical realist perspective), this research highlights the unique context of up-skilling opportunities and practices in the marine sector and reveals the crucial role of agency in workplace practices. This leads to a better understanding of the up-skilling opportunities and practices of marine professionals in South Africa, which ultimately contributes towards improved human capital development in the biodiversity and environmental sectors. Through offering more complex insights into the forms of learning and up-skilling, as well as a distinct methodological contribution, this research has broader relevance for workplace learning research.
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  • Date Issued: 2019

From myth to allegory: a study of the poetry of W.H. Auden, with special reference to the poet's intention

  • Authors: Bell, I M
  • Date: 1968
  • Subjects: Auden, W. H., (Wystan Hugh), 1907-1973 -- Criticism and interpretation
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:2290 , http://hdl.handle.net/10962/d1009514 , Auden, W. H., (Wystan Hugh), 1907-1973 -- Criticism and interpretation
  • Description: The more attentively Auden's poetry is studied, the more one critical problem emerges. How can the poet of the "twenties and ' thirties be reconciled with the poet of the last three decades? "We've all got to come to terms with the later Auden" writes Professor Richard Hoggart, but he does not explain how. The man who wrote the pungent early poetry with its constant reiteration of warnings to a sick society that what was needed was " … death, death of the grain, our death, Death of the old gang … " before it could achieve "new styles of architecture, a change of heart", seems an entirely different person from the man who is on the side of Authority to-day; that is to say in so far as Auden can ever be said to be definitely on one side or another. Intro. p. 1.
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  • Date Issued: 1968

Government policy and industrial location in South Africa

  • Authors: Bell, Robert Trevor
  • Date: 1968
  • Subjects: South Africa -- Industries -- Location Industrial relations -- Government policy -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:1079 , http://hdl.handle.net/10962/d1009507
  • Description: Governments, naturally, pursue social and political as well as economic objectives. The degree to which economic and non-economic objectives harmonise with one another without government interference, however, obviously varies a good deal according to time and place. For instance in the nineteenth century, the priorities of British governments made possible a high degree of individual freedom in the economic sphere. This century, however, as Robbins suggests, has seen a great extension of state activity in the economic sphere, for both economic and non-economic reasons. This tendency, then, is not peculiar to South Africa, but the border industries policy, largely because of its ideological associations and the degree of intervention which it seems to imply, is a particularly controversial example. Chapter 1 para 2.
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  • Date Issued: 1968

Biotic and abiotic drivers of macroinvertebrate assemblages in a South African river

  • Authors: Bellingan, Terence Andrew
  • Date: 2018
  • Subjects: Aquatic insects -- South Africa -- Eastern Cape , Stream ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape , Riparian areas -- Management , Ecosystem management -- South Africa -- Eastern Cape , Mayflies -- South Africa -- Eastern Cape , Stoneflies -- South Africa -- Eastern Cape , Keiskamma River
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/61839 , vital:28067
  • Description: Aquatic insects are the most numerically abundant and diverse group of organisms found in lotic ecosystems in South Africa and the world over. They play vital roles in freshwater ecosystem functioning, processing nutrients and in turn forming integral links in stream food-webs. This thesis focussed on examining the macroinvertebrate fauna within three reaches of headwater streams of the Keiskamma River system: reaches that were considered to be fishless; reaches that were invaded by non-native salmonid species; and reaches that were dominated by native fish. I described the effects of predatory fish presence through detailed examination of macroinvertebrate assemblage composition; macroinvertebrate drift timing and density; and through niche utilisation determined from stable isotope data. Patterns in the macroinvertebrate assemblages of the headwaters of the Keiskamma River appear to be driven more strongly by flow rate and seasonal influences, but fish presence and biotope availability were also significant drivers. Niche shifts due to predator presence were not easy to detect and, while patterns of influence may have been evident, they were not found to be significant. However, I demonstrated that salmonids selectively feed on native fish species when the opportunity is presented, occupying significantly higher trophic levels when co-occurring with native fish than in invaded reaches where native fish are absent. Drift timing and density were demonstrated to be significantly different between reach for specific macroinvertebrate species from the Ephemeroptera and Plecoptera, under differing fish predation regimes, in agreement with what has been observed from studies in rivers elsewhere. In freshwater ecosystems of South Africa and worldwide, mitigation of negative effects of alien fishes through their removal using piscicides may also affect non-target organisms. To better understand the effects of just such a removal operation, employed for the first time in the history of freshwater conservation in South Africa, macroinvertebrate communities were assessed for non-target effects of rotenone. The fish eradication operations were demonstrated to have a short-term negative effect on the macroinvertebrate assemblage, through water quality index measurements and alteration of densities of macroinvertebrate taxa collected from stone surfaces. However, no long-term detrimental impact was observed as macroinvertebrate faunas returned to a comparable pre-treatment state within a year of each rotenone application.
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  • Date Issued: 2018

How to do things with speeches: a critical discourse analysis of military coup texts in Nigeria

  • Authors: Bello, Umar
  • Date: 2020
  • Subjects: Speeches, addresses, etc., Nigerian -- 20th century -- History and criticism , Critical discourse analysis -- Nigeria , Corpora (Linguistics) , Social sciences -- Philosophy , Intertextuality , Interpellation -- Nigeria , Forensics (Public speaking) , Oratory -- Nigeria , Nigeria -- Politics and government -- 1960- , Nigeria -- Social conditions -- 1960-
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/143336 , vital:38234
  • Description: Coup speeches that usher the military into political power in Nigeria are the central focus of this thesis. There are seven coup speeches that are notable in the changing of the political course in Nigeria and in enabling the military to rule Nigeria for 30 years, establishing another alternative political construct and party (Bangura 1991). The seven coup speeches along with two others, one a colonial proclamation of conquest and the other a counter coup speech (altogether making nine) constitute the data of this thesis. The analysis done here uses Critical Discourse Analysis, based on a combination of Fairclough (1989, 2001), Fairclough and Fairclough (2012), Thompson’s (1984, 1988 and 1990) works with complementary insights by Chilton (2004), to analyze the speeches in order to understand the ideologies, perceptions and arguments of the coup makers enshrined in the texts. I also employ a concordance analytic system in corpus linguistics to sort uses of important terms and lexical items. The analysis is divided into three broad parts, namely: an analysis of representation of social actors and their action, an analysis of the processes of interpellation and then an analysis of the premises of the arguments contained in the speeches. In the concluding part, there is a discussion of the dialectical nature of the coup speeches especially in the areas of mutual influences which aids in the gradual sedimentation of the political ideology of the military. In particular, there is a longitudinal intertextual analysis across all the speeches, from the earliest to the latest, to see how a coup speech genre is created. The contribution of this work to knowledge is in terms of combining discourse analysis and social theory to illuminate some aspects of Nigeria’s socio- political crises in depth and multifariously. This work helps in understanding the nature of Nigerian autocratic democracy, subservient followership by the citizenry and the supremacy of the military elite. The work employs a novel combination of representation, argumentation, interpellation and constitutive intertextuality in understanding military discourse. It looks at speaker intention, the exploitation of interpretation or reception and the formation of subjects in general and each with its importance and social context. The work as a whole reveals that the military try to build legitimacy by way of establishing authority through rhetorical arguments in varying degrees. These arguments are laid bare, and what they discern is that charges are decidedly trumped up by the military against their opponents and constructed to suit the spin of their moments. The coup makers in some instances construct strawmen of opponents and then go ahead to attack their constructed assumptions or they charge without substance using nominalizations, metaphorical constructions and presuppositions. They apply stipulative definitions and emotionally loaded words in evaluating their actions favourably and also in the negative evaluation of the actions of the opponents. At the level of interpellational analysis, the data reveals the use of language in gradually hailing the citizens as military subjects. The role of the audience changes here i.e. from those to be convinced in rhetorical evaluation of opponents to those to be firmly controlled. The persistent hailing and positioning of the citizens as military subjects help in concretizing their subjecthood. The reaction of the people in affirmation of support to the rule of the military is crucial and it completes the interpellation process. As observed by Clark (2007, 141) “many African societies are so inured to military intervention as not to regard it as aberrant”. This inuring of the societies has to do with hegemonic ideological practices in military discourses claiming legitimacy and the right to rule. At the reception level, this shows that most of the citizens have bought into the dominant ideology and are as such interpellated by it or have adopted what Hall (2015, 125) would call the ‘dominant-hegemonic position’. Aspects of argumentation, speech acts, and deontic modals used by the coup makers help in gradually solidifying the subservient nature of the citizens to the military junta. The diachronic and intertextual nature of the analysis also reveals that the colonial proclamation of conquest in Nigeria by Lord Fredrick Lugard possibly influenced the first coup speech in 1966 in terms of structure and genre. There are traces of the colonial proclamations found in the 1966 coup speech. In substance, the military appear to copy their colonial progenitors. Historically, the military were formed as an army of colonial conquest. There is a dialectical interplay between colonial discourse and military coup speeches. The first coup speech, for its part, influences other coup speeches and they in general impact on civilian political language. The work analyzes from the minute to the global and in this bid unties the layers of assumptions, constructions and points of views that underpin an otherwise objective presentation of reality. The study also engages social theory in illuminating aspects of discourse, social practice and political action. The works of post-structuralists like Foucault, Althusser, Bourdieu, Habermas, Laclau and Mouffe, Derrida etc. are employed in shedding light on the processes of social formation in the interpellation of subjects and in the construction of a new political authority by the military regimes.
  • Full Text:
  • Date Issued: 2020

Movement patterns, stock delineation and conservation of an overexploited fishery species, Lithognathus Lithognathus (Pisces: Sparidae)

  • Authors: Bennett, Rhett Hamilton
  • Date: 2012
  • Subjects: Reef fishes -- Behavior , Endangered species -- South Africa , Fish stock assessment -- South Africa , Fishery management -- South Africa , Fish communities -- South Africa , Sparidae , Lithognathus , Lithognathus -- Growth
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5374 , http://hdl.handle.net/10962/d1015709
  • Description: White steenbras Lithognathus lithognathus (Pisces: Sparidae) has been a major target species of numerous fisheries in South Africa, since the late 19th century. Historically, it contributed substantially to annual catches in commercial net fisheries, and became dominant in recreational shore catches in the latter half of the 20th century. However, overexploitation in both sectors resulted in severe declines in abundance. The ultimate collapse of the stock by the end of the last century, and the failure of traditional management measures to protect the species indicate that a new management approach for this species is necessary. The species was identified as a priority for research, management and conservation in a National Linefish Status Report. Despite knowledge on aspects of its biology and life history, little is known about juvenile habitat use patterns, home range dynamics and movement behaviour in estuaries. Similarly, the movement and migration of larger juveniles and adults in the marine environment are poorly understood. Furthermore, there is a complete lack of information on its genetic stock structure. Such information is essential for effective management of a fishery species. This thesis aimed to address the gaps in the understanding of white steenbras movement patterns and genetic stock structure, and provide an assessment of its current conservation status. The study adopted a multidisciplinary approach, incorporating a range of methods and drawing on available information, including published literature, unpublished reports and data from long-term monitoring programmes. Acoustic telemetry, conducted in a range of estuaries, showed high site fidelity, restricted area use, small home ranges relative to the size of the estuary, and a high level of residency within estuaries at the early juvenile life stage. Behaviour within estuaries was dominated by station-keeping, superimposed by a strong diel behaviour, presumably based on feeding and/or predator avoidance, with individuals entering the shallow littoral zone at night to feed, and seeking refuge in the deeper channel areas during the daytime. Conventional dart tagging and recapture data from four ongoing, long-term coastal fish tagging projects, spread throughout the distribution of this species, indicated high levels of residency in the surf zone at the late juvenile and sub-adult life stages. Consequently, juvenile and sub-adult white steenbras are vulnerable to localised depletion, although they can be effectively protected by suitably positioned estuarine protected areas (EPAs) and marine protected areas (MPAs), respectively. It has been hypothesized that adult white steenbras undertake large-scale coastal migrations between summer aggregation areas and winter spawning grounds. The scale of observed coastal movements was correlated with fish size (and age), with larger fish undertaking considerably longer-distance coastal movements than smaller individuals, supporting this hypothesis. Given the migratory behaviour of adults, and indications that limited spawning habitat exists, MPAs designed to protect white steenbras during the adult life stage should encompass all known spawning aggregation sites. The fishery is plagued by problems such as low compliance and low enforcement capacity, and alternative management measures, such as seasonal closure, need to be evaluated. Despite considerable conventional dart tagging effort around the coastline (5 782 fish tagged) with 292 recaptures there remains a lack of empirical evidence of fish migrating long distances (> 600 km) between aggregation and spawning areas. This uncertainty in the level of connectivity among coastal regions was addressed using mitochondrial DNA sequencing and genotyping of microsatellite repeat loci in the nuclear genome, which showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the white steenbras core distribution showed high genetic diversity, low genetic differentiation and no evidence of isolation by distance or localised spawning. Although historically dominant in several fisheries, analysis of long-term commercial and recreational catch data for white steenbras indicated considerable declines and ultimately stock collapse. Improved catch-per-unit-effort in two large MPAs subsequent to closure confirmed that MPAs can be effective for the protection of white steenbras. However, the current MPA network encompasses a low proportion of sandy shoreline, for which white steenbras exhibits an affinity. Many MPAs do not prohibit recreational shore angling, which currently accounts for the greatest proportion of the total annual catch. Furthermore, EPAs within the juvenile distribution protect a negligible proportion of the total available surface area of estuaries – habitat on which white steenbras is wholly dependent. Despite some evidence of recent increases in abundance in estuaries and the surf zone in certain areas, white steenbras meets the criteria for “Endangered” on the IUCN Red List of Threatened Species, and for “Protected species” status on the National Environmental Management: Biodiversity Act of South Africa. The species requires improved management, with consideration for its life-history style, estuarine dependency, surf zone residency, predictable spawning migrations and its poor conservation status. The multidisciplinary approach provides valuable information towards an improved scientific basis for the management of white steenbras and a framework for research that can be adopted for other overexploited, estuarine-associated coastal fishery species.
  • Full Text:
  • Date Issued: 2012

The application of human factors and ergonomics (HFE) to community-sport organisations in resource scarce contexts: a case study of grassroots football in Makana, Eastern Cape

  • Authors: Bennett, Ryan
  • Date: 2021
  • Subjects: Makana Local Football Association (South Africa) , Human engineering , Soccer teams -- South Africa -- Makhanda -- Management , Soccer -- Management -- South Africa
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/172412 , vital:42198 , 10.21504/10962/172412
  • Description: Background: Modern Human Factors and Ergonomics (HFE) focuses on the optimisation of complex socio-technical systems and has been challenged to contribute to broader societal issues. An example is within grassroots football organisations in resource-scarce areas such as Makana, South Africa. Through embedded participatory approaches, the research problem was co-constructed: To investigate the socio-technical system of the Makana Local Football Association (LFA). Method: A useful complex system modelling tool is that of Cognitive Work Analysis (CWA), with its 5 phases used to identify constraints and affordances. Three perspectives were adopted for the application of an adapted (to suit participant characteristics) CWA to the Makana LFA: 1) how work is prescribed by the governing body SAFA, 2) how subject matter experts (SME) disclose its current functioning, and 3) how SMEs imagine it could function. Five SMEs attended 12 three-hour workshops to complete the latter two perspectives. Results: The composite work domain analysis between work as prescribed and work as disclosed identified significant mismatches between how policymakers envision the system and how SMEs report its functioning. Key differences in perspectives included the fundamental purpose of the Makana LFA, while only four of 22 functions operate within the Makana LFA. Participants also identified key affordances for the LFA such as reorientation as a community sports organisation. Discussion: Comparison between perspectives indicated four mismatches. 1) SAFA views the LFA as the foundation of the talent identification and development infrastructure of South African football. SMEs view it as a community centred organisation. 2) A lack of human capacity is evident at the community level of Makana football. 3) Funding and assets are absent at this grassroots level. 4) The LFA relies on other stakeholders, but these relationships are not formalised. Policymakers, therefore, have a lack of knowledge of the contextual challenges faced by LFA administrators. It is recommended that SAFA view the LFA as a community sport organisation, focusing on improving human capacity, increasing funding, and formalising stakeholder networks. Furthermore, conceptual models from CWA provide explicit socio-technical system redesign recommendations. Conclusion: Large mismatches between the organising body SAFA and the actual functioning of the LFA significantly hinder the effective management and running of football at a grassroots level in resource-scarce contexts in South Africa. The perspectives approach to CWA was useful in elucidating the constraints and affordances of the Makana LFA socio-technical system and informing redesign opportunities. Systems HFE methodology is therefore well placed to contribute to broader societal issues within resources scarce contexts such as football in Makana. Furthermore, the philosophical underpinnings of systems based HFE were successful in the development of sustainable participatory research within the South African grassroots football context.
  • Full Text:
  • Date Issued: 2021

Biochemical characterisation and small molecule modulation of the interaction between two cytosolic Hsp70s from Trypanosoma brucei and potential co-chaperones

  • Authors: Bentley, Stephen John
  • Date: 2018
  • Subjects: Uncatalogued
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/63402 , vital:28407
  • Description: Expected release date-April 2019
  • Full Text:
  • Date Issued: 2018

Spatial and temporal variations in trophic connectivity within an estuarine environment : benthic-pelagic and terrestrial-aquatic linkages via invertebrates and fishes

  • Authors: Bergamino Roman, Leandro
  • Date: 2015
  • Subjects: Estuarine ecology -- South Africa , Marine invertebrates -- South Africa -- Ecology
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5921 , http://hdl.handle.net/10962/d1017799
  • Description: Estuarine ecosystems are among the most biologically productive areas and they provide important ecosystem services such as erosion control, habitat and refugia for several species. These environments are characterized by the presence of a variety of organic matter sources due to their transitional position between rivers and the sea. The biotic compositions can undergo spatial and seasonal changes along the estuary due to the spatial and temporal fluctuations of environmental factors such as salinity, temperature and seston loads. Therefore, the different combinations of biotic and abiotic factors make each estuary a unique ecosystem. Because of this spatial and temporal complexity, the understanding of estuarine food web structure and which factors affect the trophic relationships within the ecosystem through space and time represent challenging tasks. Furthermore, estuaries are under an increasing number of anthropogenic perturbations because of the growing concentration of human populations in coastal areas. Knowledge of ecosystem structure and functioning is essential for effective conservation and management planning of coastal areas.In this dissertation, I combine the utilization of biological tracers to examine spatial and temporal variability in the food web structure within a small temperate and microtidal estuary located in South Africa. To this end, fatty acid profiles and stable isotope signatures were measured in several primary organic matter sources and consumers (including zooplankton, fishes and benthic invertebrates) during four consecutive seasons and in three different estuarine regions: upper, middle, and lower reaches. The three reaches had distinct habitat features of vegetation type and morphology, and in particular the lower reaches were colonized by the marsh grass Spartina maritima. Isotopic mixing models were used to estimate the relative contribution of each food source to the diets of invertebrates and fishes within the estuarine food web. The isotopic and fatty acid data showed similar results. In general, the lower reaches of the estuary were characterized by a higher deposition and assimilation by brachyuran crabs of carbon derived from marsh grass detritus, whiletowards the upper reaches a mixture of microphytobenthos and particulate organic matter (phytoplankton and detritus) was deposited and sustained the pelagic and benthic fauna. The highest deposition and assimilation of marsh grass detritus in the lower reaches of the estuary occurred during periods of low freshwater discharge (autumn and winter). In the upper reaches, microphytobenthos and suspended particulate organic matter were dominant basal food resources for the food web during all seasons. These results indicated that benthic consumers incorporated mainly local carbon sources from their local habitat.To clarify isotopic and fatty acid patterns I examined the trophic behaviour of the sesarmid crab Sesarma catenata through laboratory feeding experiments. Results from these experiments validated that decomposed leaves of riparian trees and the salt marsh plant S. maritima were the preferred food of the sesarmid crabs, potentially due to high bacterial loads. The remaining leaf material not assimilated by crabs, together with faecal material, are likely important subsidies for adjacent environments, hence representing an important energy pathway involving the microbial food chain. Furthermore, this dissertation showed the importance of mobile top predators as vectors energetically connecting distinct food chains within the estuary (i.e. littoral, benthic and pelagic). I concluded that a combination of physical (i.e. patterns of freshwater discharge and estuary morphology) and biological factors (i.e. organism feeding behaviour, mobility, primary productivity, the local vegetation type) influence the pattern of dominant primary organic matter sources, and therefore the food web structure along the estuarine environment. In particular, marsh grass detritus contributed substantially to the diets of estuarine fauna during periods of low freshwater discharge. Given the importance of the salt marsh habitat in providing trophic resources, it is important to preserve this environment to sustain the natural biota and ecosystem functioning.
  • Full Text:
  • Date Issued: 2015

Social structure and rural economic development

  • Authors: Berger, Guy
  • Date: 1989
  • Subjects: Social structure -- Developing countries , Rural development-- Developing countries
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:2864 , http://hdl.handle.net/10962/d1007643
  • Description: New concepts and a synthesis of existing theories may assist in studying the relationship between social structure, development and rural development. The concept of social structure encompasses the concept of economic structure which may be analysed in terms of three "Moments" of production. On this basis, one can distinguish between heterogeneous and homogeneous relations of production structures. "Homogeneous relations" together with "system dynamics" and ''reproduction", define the concept of a mode of production. "Development" refers to the expansion of total productive capacity, premissed on advanced means of production, and corresponding to the particular relations and forces of production in an economic system. The capitalist mode of production has both tendencies and countertendencies to development. The latter prevail in the Third World due to the admixture and heterogeneity of production relations there, and to their subordinate articulation within an international capitalist economic system. In this context, underdevelopment is the result of the specific factors of monopoly competition, dependence-extraversion, disarticulation-unevenness, the three-tier structure of the peripheral economy, surplus transfer, and class structures and struggles. Rural development can be understood in terms of the specific contribution of agriculture to development, theorized as the "Agrarian Question". Agrarian capitalism has been slow to develop in the Third World, and the state of agriculture remains a problem there. "Rural development" has emerged as a deliberate and interventionist state strategy designed to restructure agrarian relations for development. This has contributed to the formation of particular heterogeneous relations of production articulated to the capitalist mode. In this context, the character of the associated classes has left the Agrarian Question unresolved. "Rural development" continues because it has an important~ and even primary, political significance - although this is not without contradictions.
  • Full Text:
  • Date Issued: 1989

Towards a cost-efficient & standardised monitoring protocol for subtidal reef fish in the Agulhas ecoregion of South Africa

  • Authors: Bernard, Anthony Thomas Firth
  • Date: 2013
  • Subjects: Reef fishes -- South Africa Reef fishes -- Monitoring--South Africa Fish stock assessment -- South Africa Coastal zone management -- South Africa Fish communities -- South Africa Marine parks and reserves -- South Africa Marine resources conservation -- South Africa Marine biodiversity conservation -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5585 , http://hdl.handle.net/10962/d1001674
  • Description: Under the growing demand for marine fish resources, and the apparent and expected impacts of global climate change, there is a need to conduct long-term monitoring (LTM) to ensure effective management of resources and conservation of biodiversity. However LTM programmes often suffer from design deficiencies and fail to achieve their objectives. These deficiencies stem from the fact that insufficient consideration is afforded to the design phase, with programmes selecting methods that are not suitable to address the objectives, or are not cost-efficient, compromising the sustainability of the LTM. To facilitate the establishment of LTM programmes along the southern coast of South Africa, background research needed to be conducted to identify which methods were most appropriate for LTM of reef fish. This study presents a detailed field-based assessment of the suitability and cost-efficiency of monitoring methods for long-term monitoring of reef fish in the Agulhas Ecoregion of South Africa. The approach adopted to identify the method, or suite of methods most suited for LTM, involved (i) the selection of methods considered suitable for LTM, (ii) the individual assessment and optimisation of method performance, and (iii) the comparative assessment of the fish community sampled by the different methods. The most suited method(s) were then identified as those that provide the most comprehensive assessment of the fish community and had the highest cost-efficiency. The research was conducted between January 2008 and 2011 in the Tsitsikamma and Table Mountain National Park (TNP and TMNP, respectively) marine protected areas (MPAs) within the Agulhas Ecoregion. The methods selected included fish traps (FT), controlled angling (CA), underwater visual census (UVC), remote underwater video (RUV), baited RUV (BRUV) and remotely operated vehicles (ROV). The individual assessment and optimisation was conducted with the FT, UVC, RUV and BRUV methods. The assessment of the FT method aimed to identify the optimal soak time, and whether or not the size of the funnel entrance to the trap affected the catch. The results identified that larger funnel entrances caught more fish and soak times of 80 minutes produced the highest catches per unit effort. However the data were highly variable and the method detected few of the species typical of the region. Fish traps were also associated with high levels of mortality of fish post-release. The assessment of UVC strip transect method involved directly comparing the precision of data collected by researchers and volunteers using a novel double-observer technique (paired-transects). The results showed considerable error in both the volunteers and researchers data, however the researchers produced significantly higher precision data, compared to the volunteers. The distinction between researchers and volunteers was not evident in the data for the dominant species of fish. For all observers, the abundance of a species in the sample had a significant influence on its detectability, with locally scarce or rare species poorly detected. UVC was able to sample the majority of species typical of reefs in the region, however it appeared plagued by observer and detectability biases. The assessments of RUV and BRUV were conducted simultaneously which enabled the assessment of the effect of bait on the observed fish community. In addition the optimal deployment time for both methods to maximise species richness and abundance was determined. The results showed that BRUV, and to a lesser degree RUV, were able to effectively survey the reef fish community for the region with a 50 minute and 35 minute deployment time, respectively. Baited remote underwater video was especially good at detecting the invertebrate and generalist carnivores, and cartilaginous species. On the other hand, RUV was more effective at surveying the microinvertebrate carnivores. Remote underwater video was characterised by higher data variability, compared to BRUV, and was ultimately considered a less cost-efficient monitoring method. Comparative methods assessments were conducted during two field experiments with the FT, UVC and BRUV methods in the TMNP MPA, and the FT, CA, UVC, RUV, BRUV and ROV methods compared in the TNP MPA. The objectives of the comparison were to investigate differences in the fish communities observed with the different methods, and to determine the power of the data to detect an annual 10% growth in the fish populations over a period of five years. The results from the method comparison were in turn used to conduct the cost-benefit analysis to determine the efficiency of the different methods at achieving monitoring objectives requiring population data from multiple trophic and functional groups with the community, and from species of fisheries importance. The results indicated that FT, CA and ROV were ineffective at monitoring the reef fish community, although CA appeared to provide valuable data for the dominant fisheries species. Both CA and FT required minimal initial investment however, the variability in the data translated into high annual monitoring costs, as the required sampling effort was great. The ROV required the highest initial investment and was identified as the least cost-efficient method. Underwater visual census was able to adequately survey the bony fish within the community, however it did not detect the cartilaginous species. Underwater visual census required a large initial investment and was not cost-efficient, as a many samples were required to account for the variability in the data. Remote underwater video provided a comprehensive assessment of the reef fish community, however it too was associated with high levels of variability in the data, compared to BRUV, reducing its cost-efficiency. BRUV provided the most comprehensive assessment of the reef fish community and was associated with the highest cost-efficiency to address the community and fisheries species monitoring objectives. During the course of this research stereo-BRUV has gained considerable support as an effective reef fish monitoring method. Although not tested during this research, stereo-BRUV is preferred to BRUV as it provides accurate data on the size of fish. However, the initial investment of stereo-BRUV is over three times that required for the BRUV. Although it is recommended that a baited video technique be used for LTM in the Agulhas Ecoregion, the choice between BRUV and stereo-BRUV will depend on the specific objectives of the programme and the available budget at the implementing agency.
  • Full Text:
  • Date Issued: 2013

Influence of increased processing speed on the microstructure evolution and mechanical property relationship in friction stir welding of AA5182-H111 (T500)

  • Authors: Bernard, Dreyer
  • Date: 2016
  • Subjects: Friction stir welding , Aluminum alloys -- Welding
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10948/7322 , vital:21319
  • Description: Friction stir welding of 5xxx series aluminium is generally carried out at low travel speeds, which limits the commercial applications of this process. This manuscript discusses the dynamic eformation characteristics of AA5182-H111 (T500), which allowed a travel speed of 1500 mm/min to be realised. This was achieved by using a spindle speed of 500 rev/min; the same as that required to make a weld of 200 mm/min. The thermal cycles, microstructural evolution due to tool / work-piece interaction, and the local microstructural and mechanical properties of the completed weld are discussed for a travel speed for 200 mm/min and 1500 mm/min. At a rate of 200 mm/min, heat generated due to contact between the shoulder and work-piece surface was transferred ahead of the tool, driving dynamic recrystallization which lowered the flow stress. Hereafter the material entered the stir zone where it was extruded around the pin during a process of continuous dynamic crystallization. At a travel speed of 1500 mm/min, the rate of heat conduction ahead of the tool was not rapid enough, and the material was deformed at low temperatures. A low weld pitch rotations per unit length travelled) was required to ensure that the material was sufficiently strained, to allow the formation of geometric necessary boundaries, which resulted in grain subdivision. The number of high angle grain boundaries was increased through subdivision, thus, increasing the nucleation sites for dynamically recrystallized necklace grains to form. In the absence of heat conduction from the shoulder, the high plastic strain ahead of the tool provided the energy required to drive dynamic recrystallization. Heat was generated from the high plastic strain and during recrystallization, where the stored plastic energy was adiabatically released. Once the material entered the stir zone, the high strain rates associated with the tool rotation which drove dynamic recrystallization that allowed the material to reach high levels of strain, resulted significant grain refinement. The weld zone of the 200 mm/min displayed weld a slight increase in yield strength, with respect to the parent material, due to grain refinement to 10 μm, while the yield strength of the 1500 mm/min weld was significantly increased due to grain refinement to 5 μm. The high weld speed did, however, generate high tensile residual stresses. This work is not only significant for the field of friction stir welding, but also in terms of material processing. The dynamic deformation characteristics associated with Al-5Mg-Mn, alloys which was observed ahead of the tool, is of high value in processes where plastic deformation is applied to improve the mechanical properties of these alloys.
  • Full Text:
  • Date Issued: 2016

The role of the euthecosome pteropod, limacina retroversa, in the polar frontal zone, Southern Ocean

  • Authors: Bernard, Kim Sarah
  • Date: 2007
  • Subjects: Pteropoda Limacidae Zooplankton -- Antarctic Ocean Copepoda Phytoplankton
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:5761 , http://hdl.handle.net/10962/d1005449
  • Description: The aim of the present study was to assess the ecological role of the euthecosome pteropod, Limacina retroversa, in particular, and the mesozooplankton community, in general, in the pelagic ecosystem of the Polar Frontal Zone (PFZ), Southern Ocean. Data were collected from four oceanographic surveys to the Indian sector of the PFZ during austral autumn 2000, 2002, 2004 and 2005. Copepods, mainly Calanus simillimus, Oithona similis, Clausocalanus spp. and Ctenocalanus spp., typically dominated total mesozooplankton counts, accounting for, on average, between 75.5 % and 88.1 % (Mean = 77.4 %; SD = 13.4 %) of the total, during the present investigation. Results of the study indicate that L. retroversa may, at times, contribute substantially to total mesozooplankton abundances. During the study, L. retroversa contributed between 0.0 and 30.0 % (Mean = 5.3 %; SD = 7.1 %) to total mesozooplankton numbers. Significant small-scale variability in abundance and size structure of L. retroversa and abundance of copepods was minimal. Inter-annual variability, on the other hand, was significant between some years. Total pteropod numbers were greatest during April 2002 and 2004, while copepods exhibited greatest abundances during April 2004 only. Pearson’s Correlation analysis suggested that L. retroversa abundances were positively correlated to total surface chlorophyll-a (chl-a) concentrations. The significantly lower chl-a concentrations recorded during April 2005 may explain the reduced pteropod numbers observed during that survey. The size class structure of L. retroversa comprised mainly small and mediumsized individuals during all four surveys. This corresponds well with records from the northern hemisphere (sub-Arctic and Arctic waters) where Limacina spp. are reported to exhibit maximum spawning during mid to late-summer. Higher abundances of large individuals only occurred during April 2005, when chl-a concentrations were very low; possibly the result of delayed spawning, due to reduced food availability. Ingestion rates of the four most abundant copepods, determined using the gut fluorescence technique, ranged between 159.32 ng (pigm) ind⁻¹ day⁻¹ and 728.36 ng (pigm) ind⁻¹ day⁻¹ (Mean = 321.01 ng (pigm) ind⁻¹ day⁻¹; SD = 173.91 ng (pigm) ind⁻¹ day). Ingestion rates of L. retroversa were much higher, ranging from an average of 4 28.68 ng (pigm) ind⁻¹ day⁻¹ in April 2002 to 4 196.88 ng (pigm) ind⁻¹day⁻¹in April 2005 (Mean = 4157.36 ng (pigm) ind⁻¹ day⁻¹; SD = 35.37 ng (pigm) ind⁻¹day⁻¹). Average daily grazing rates for the pteropod varied between 0.39 mg (pigm) m⁻² day⁻¹ in April 2005 and 17.69 mg (pigm) m-2 day-1 in April 2004 (Mean = 6.13 mg (pigm) m⁻² day⁻¹; SD = 11.04 mg (pigm) m⁻² day⁻¹); corresponding average daily grazing impacts ranged between 8.4 % and 139.8 % of the phytoplankton standing stock in April 2005 and 2004, respectively (Mean = 48.5 %; SD = 84.5 %). Average daily grazing rates of the four copepods ranged from 4.58 mg (pigm) m⁻² day⁻¹ to 8.77 mg (pigm) m⁻² day⁻¹ -1, during April 2002 and 2004, respectively (Mean = 6.28 mg (pigm) m⁻² day⁻¹; SD = 5.94 mg (pigm) m⁻² day⁻¹). Collectively, the copepods removed an average of between 31.6 % and 89.8 % of the phytoplankton standing stock per day, during April 2002 and 2004, respectively (Mean = 70.8 %; SD = 86.7 %). The daily grazing impact of the copepods accounted for an average of between 40.4 % and 87.8 % of the total zooplankton grazing impact, during April 2004 and 2005, respectively (Mean = 75.0 %; SD = 65.5 %). L. retroversa was responsible for an average of 52.4 % and 59.5 % of the total zooplankton grazing impact, during April 2002 and 2004, respectively. However, during April 2005, when L. retroversa numbers were significantly lower than previous years, the pteropod contributed an average of only 7.5 % to the total zooplankton grazing impact. Thus, during the present investigation,the pteropod was responsible for removing a mean of 48.9 % of the available phytoplankton (SD = 74.9 %). The predation impact of the dominant carnivorous macrozooplankton and micronekton in the PFZ was determined during April 2004 and 2005 using daily ration estimates obtained from the literature. Additionally, gut content analysis was used to determine the contribution of L. retroversa to the diet of the dominant predators. Average predation impact ranged from 1.1 % and 5.7 % of the total mesozooplankton standing stock during April 2004 and 2005, respectively (Mean = 3.8 %; SD = 12.3 %). Chaetognaths and euphausiids dominated total carnivore numbers and made the greatest contributions to total predation impact during both years. Copepods appeared to be the main prey item of the dominant carnivorous macrozooplankton-micronekton in the region. L. retroversa was only detected in the gut contents of the amphipod, Themisto gaudichaudi, but not in either of the chaetognath species (Eukrohnia hamata and Sagitta gazellae) or the myctophid fish (Electrona spp.). The pteropod was found in 19 % of amphipod guts dissected. Pearson’s Correlation analyses showed that the four major predatory zooplankton groups found in the PFZ (chaetognaths, euphausiids, amphipods and myctophid fish) were positively correlated to abundances of L. retroversa, suggesting that the pteropod might be an important prey item for many of the carnivorous macrozooplankton/micronekton in the PFZ. To conclude, L. retroversa may play an important role in the pelagic ecosystem of the PFZ, in austral autumn. However, ocean acidification and calcium carbonate undersaturation (as a result of increased anthropogenic carbon dioxide emissions), that is predicted to occur within the next 50 – 100 years, will most likely have significant implications for the Sub-Antarctic pelagic ecosystem if L. retroversa cannot adapt quickly enough to the changes.
  • Full Text:
  • Date Issued: 2007

Messages from the deep : water divinities, dreams and diviners in Southern Africa

  • Authors: Bernard, Penelope Susan
  • Date: 2010
  • Subjects: Dreams -- Religious aspects , Zulu (African people) -- Religion , Xhosa (African people) -- Religion , Shamanism -- South Africa
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: vital:2112 , http://hdl.handle.net/10962/d1007644 , Dreams -- Religious aspects , Zulu (African people) -- Religion , Xhosa (African people) -- Religion , Shamanism -- South Africa
  • Description: This thesis is a comparative regional study of a complex of beliefs and practices regarding the water divinities in southern Africa. These snake and mermaid-like divinities, which are said to work in conjunction with one's ancestors, are believed to be responsible for the calling and training of certain diviner-healers by taking them underwater for periods of time. In addition to granting healing knowledge, these divinities are associated with fertility, water and rain, and the origins of humanity. The research combines comparative ethnography with the anthropology of extraordinary experience (AEE), and focuses particularly on the Zulu, Cape Nguni, Shona and Khoisan groups. The use of the 'radical participation' method, as recommended by AEE, was facilitated by the author being identified as having a ' calling' from these water divinities, which subsequently resulted in her initiation under the guidance of a Zulu isangoma (diviner-healer) who had reputedly been taken underwater. The research details the rituals that were performed and how dreams are used to guide the training process of izangoma. This resulted in the research process being largely dream-directed, in that the author traces how the izangoma responded to various dreams she had and how these responses opened new avenues for understanding the phenomenon of the water divinities. The comparative study thus combines literature sources, field research and dream-directed experiences, and reveals a complex of recurring themes, symbols and norms pertaining to the water divinities across the selected groups. In seeking to explain both the commonalities and differences between these groups, the author argues for a four-level explanatory model that combines both conventional anthropological theory and extraordinary experience. Responses to the author's dream-led experiences are used to throw light on the conflicting discourses of morality regarding traditional healers and the water divinities in the context of political-economic transformations relating to capitalism and the moral economy; to illuminate the blending of ideas and practices between Zulu Zionists and diviner-healer traditions; and to link up with certain issues relating to San rock art, rain-making and healing rituals, which contribute to the debates regarding trance-induced rock art in southern Africa.
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  • Date Issued: 2010
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