An investigation of the barriers and drivers to CDM renewable energy investment at the Metro, Kouga and Jeffreys Bay windfarms
- Authors: Staples, Daryl Nolan
- Date: 2016
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:871 , http://hdl.handle.net/10962/d1021316
- Description: This research is presented in three sections. Section 1 presents the research report in an academic journal article format. Section 2 provides a comprehensive literature review and Section 3 describes the research methodology and methods employed during the research. Climate change is the most urgent challenge facing planet earth today. The Intergovernmental Panel on Climate Change (IPCC) fifth assessment report (AR5) clearly states, “Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems” (IPCC, 2014:2). The Renewable Energy Policy Network for the 21st Century (REN21) published the 10th annual edition of the Renewables 2015 Global Status Report, which illustrates the importance of a zero emissions energy sector (REN21, 2015). Despite the world’s average annual 1,5% increase in energy consumption in recent years, and average 3% growth in Gross Domestic Product, carbon dioxide (CO2) emissions in 2014 were unchanged from 2013 levels (REN21, 2015). The report findings state, “For the first time in four decades, the world economy grew without a parallel rise in CO2 emissions” (REN21, 2015:17). Renewable energy and improved energy efficiency is key to limiting global warming and avoiding dangerous impacts from climate change (REN21, 2015). With a view to the successful outcome of the 21st Conference of the Parties (COP21) in December 2015, renewable energy could contribute significantly in mitigating climate change and supporting the Sustainable Development Goals (SDGs), specifically SDG 7, on Sustainable Energy for All (SAIREC, 2015). South Africa has been rated the 15th most attractive destination for investment in the renewable energy sector and could become a renewable energy leader in the African continent, according to the Renewable Energy Country Attractiveness Index of EY (Ernest and Young) (EY, 2015). And more...
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Dialogues of sexualities: An action research project
- Authors: Graham, Nicola Susan Jearey
- Date: 2016
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3275 , http://hdl.handle.net/10962/d1021271
- Description: Risky and abusive sexual behaviours, stemming largely from inequitable gendered norms, are a pervasive feature of the South African socio-sexual landscape. Literature shows that sexuality education programmes can be effective in reducing risky sexual practices, but South African school sexuality education has been shown to be largely inadequate. The question arises as to how to engage with high school learners about sexualities in meaningful ways. In an attempt to answer this, I implemented a dialogical sexuality action research project at a lower middle class urban high school. Freirian principles of critical consciousness and dialogical pedagogy were utilized, and these were infused with feminist post-structural understandings of a discursively constituted subject. The initial consultative process started in 2012 with two projects at the school. Data from these projects, and a further consultation with the school principal, provided baseline information on the gendered norms and the sexuality education in the school. I then instituted a dialogical sexuality intervention with a group of Grade 10 learners, aiming to bring gendered and sexual norms to visibility, to trouble them (thereby promoting participants’ critical consciousness around gendered norms), and to provide recognition for participants in a variety of subject positions. Ten sessions were conducted, with the focus of each session being planned by the group. The action research project attempted to promote understandings of the processes required to facilitate such aims. The dialogical format of the group generated curiosity and engagement, and there were suggestions that some participants were taking up safe-sex messages in a reflexive manner. A partial normalisation of some ‘hidden’ aspects of sex, particularly around issues pertaining to female sexuality, was enabled, and critical consciousness around the gendered inequities in ‘cheating’ was promoted. However, abstinence was relatively silenced, and male same-sex remained heavily stigmatised. No substantial action component beyond the group meetings was generated. Participant feedback indicated that they placed great value on the dialogical processes in the group, and that they enjoyed being able to talk about sexual and other personal aspects of their lives. I theorise that the value of the group was in the recognition that participants received as they were positioned in a variety of subject positions. Whilst dialogue was shown to be extremely valuable, there were suggestions that other, non-dialogical modes of recognition were also needed by participants.
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Characterisation of the HSP70-HSP90 organising protein gene and its link to cancer
- Authors: Weeks, Stacey
- Date: 2015
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/56006 , vital:26764
- Description: HOP (Heat shock protein 70/ Heat shock protein 90 organising protein) is a co-chaperone essential for client protein transfer from HSP70 to HSP90 within the HSP90 chaperone machine and has been found to be up-regulated in various cancers. However, minimal in vitro information can be found on the regulation of HOP expression. The aim of this study was to analyse the HOP gene structure across known orthologues, identify and characterise the HOP promoter, and identify the regulatory mechanisms influencing the expression of HOP in cancer. We hypothesized that the expression of HOP in cancer cells is likely regulated by oncogenic signalling pathways linked to cis-elements within the HOP promoter. An initial study of the evolution of the HOP gene speciation was performed across identified orthologues using Mega5.2. The evolutionary pathway of the HOP gene was traced from the unicellular organisms to fish, to amphibian and then to land mammal. The synteny across the orthologues was identified and the co-expression profile of HOP analysed. We identified the putative promoter region for HOP in silico and in vitro. Luciferase reporter assays were utilized to demonstrate promoter activity of the upstream region in vitro. Bioinformatic analysis of the active promoter region identified a large CpG island and a range of putative cis-elements. Many of the cis-elements interact with transcription factors which are activated by oncogenic pathways. We therefore tested the regulation of HOP levels by rat sarcoma viral oncogene homologue (RAS). Cancer cell lines were transfected with mutated RAS to observe the effect of constitutively active RAS expression on the production of HOP using qRT-PCR and Western Blot analyses. Additionally, inhibitors of the RAS signalling pathway were utilised to confirm the regulatory effect of mutated RAS on HOP expression. In cancer cell lines containing mutated RAS (Hs578T), HOP was up-regulated via a mechanism involving the MAPK signalling pathway and the ETS-1 and C/EBPβ cis-elements within the HOP promoter. These findings suggest for the first time that Hop expression in cancer may be regulated by RAS activation of the HOP promoter. Additionally, this study allowed us to determine the murine system to be the most suited genetic model organism with which to study the function of human HOP.
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Electrospun nanofibers as solid phase extraction sorbents and support for alkylphenols colorimetric probes
- Authors: Tancu, Yolanda
- Date: 2014
- Subjects: Nanofibers , Electrospinning , Extraction (Chemistry) , Sorbents , Phenols , Colorimetry , Transmission electron microscopy , High resolution spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4486 , http://hdl.handle.net/10962/d1012997
- Description: The thesis reports on fabricating alternative solid phase extraction (SPE) sorbents and colorimetric probes based on electrospun nanofibers for alkylphenols (APs). Hydroxyl methylated styrene [poly(co-styrene-CH₃OH)] and 3-oxobutanoate styrene [poly(co-styrene-OCOCH₃COCH₃)] copolymers were synthesized and fabricated into sorbent materials by electro-spinning/spraying. The fabricated morphologies consisting of bead free fibers, beaded fibers and particles were evaluated as SPE sorbents using batch experiments. Electropun fibers proved to be better sorbents as they exhibited extraction efficiency that exceeded 95% compared to 60% for beaded fibers and 40% for particles. In view to reduce sample and solvent volumes, smooth fibers were packed into pipette tips as SPE devices that yielded quantitative recoveries of APs from spiked wastewater samples. Recoveries ranged from 70% to 125% with LOD of 0.008, 0.01 and 0.1 μg mL⁻¹ for 4-tert octylphenol (4-t-OP), 4-octylphenol (4-OP) and 4-nonylphenol (4-NP) respectively, when using high performance liquid chromatography-fluorescence detector (HPLC-FLD). Furthermore, amino functionalised polydiacetylene polymers (PDAs), citrate capped gold (AuNPs) and silver nanoparticles (AgNPs) were evaluated as colorimetric probes for visual detection of APs. In colloidal studies, AuNPs probe showed a colour change from wine red to green upon introduction of analyte. UV-vis spectroscopy revealed the shifting of the surface plasmon resonance (SPR) peak from 525 nm to 729 nm induced by aggregation of AuNPs. For AgNPs probe, a colour change was observed from yellowish green to brown. Transmission electron microscopy (TEM) studies showed growth of AgNPs. A presumed oxidation of the analyte, forming an absorbing compound at 279 nm in both AgNPs and PDAs probes was also observed. For PDAs probe the colour change was from purple to pink. Concentrations as low as 30 μg mL⁻¹ were detectable in all colloidal based probes. Further colorimetric investigations were conducted with electrospun AuNPs-nylon 6 fiber mat. A colour change from purplish red to navy blue at concentrations of 1000 μg mL⁻¹ was observed. Electrospun AgNPs –nylon 6 fiber mat did not show a distinct colour change. High resolution scanning electron microscopy (HRSEM) revealed the analyte inducing the assembly of AuNPs and AgNPs as they covered the surface of the nanofiber mat. Electrospun nanofibers are a platform for analysis and thus tuning their chemistry will lead to sensitive and selective methods
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An investigation of how grade 10 learners make sense of concepts on refraction of light through exploring their cultural beliefs/everyday experiences about the rainbow : a case study
- Authors: Homateni, Rauha Kau Ndahalomwenyo
- Date: 2013
- Subjects: Science -- Study and teaching (Secondary) -- Namibia Light -- Study and teaching Light -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1827 , http://hdl.handle.net/10962/d1003713
- Description: This study took place at a private high school in the Kavango region with my 32 grade 10B learners as the research participants. Its objective was to investigate how the grade 10 learners make sense of concepts on refraction of light through exploring their cultural beliefs/everyday experiences about the rainbow. This research study was essentially triggered by my own classroom experience of teaching the topic on refraction of light. In order to achieve the goal of this research, a qualitative case study located within an interpretive paradigm was adopted. To gather data I used multiple data gathering techniques such as brainstorming session, learners conducting interviews in the community, practical activities and focus group interviews. This resulted in descriptive data that qualified to be analyzed in a qualitative way. The themes that emerged from the generated data were coded using upper letter cases and various colours. A methodological triangulation was employed by using multiple data generation techniques. Member checking during focus group interviews also ensured validity in this case study. The findings of this study revealed that the use of learners’ cultural beliefs/everyday experiences can be used to enhance learner engagement, meaning making and conceptual development during the science lessons. In addition, the ways in which practical activities are designed and presented to learners in the science classroom determine learners’ participation and conceptual attainment. Therefore, based on my research findings, I recommend that teachers need to be trained to be able to elicit and integrate learners’ cultural beliefs/everyday experiences in conjunction with hands-on practical activities which focus on conceptual development during their science lessons. However, although this study had many benefits, it also showed that it is not easy to close the gap between learners’ prior everyday knowledge and school science. This warrants further research.
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Cluster centre principals' perceptions of the implementation of the school cluster system in Namibia
- Authors: Aipinge, Lydia P
- Date: 2008
- Subjects: School management and organization -- Namibia Education -- Namibia School principals -- Namibia Educational leadership -- Namibia Educational change -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1449 , http://hdl.handle.net/10962/d1003330
- Description: The School Clustering System (SCS) was introduced five years after Namibia’s independence in 1990. The rationale for its implementation was to improve the quality of education in Namibian schools by enabling the sharing of resources, experience and expertise among clusters and facilitating school administration by pooling resources from several schools to be shared equally. It was piloted in Rundu and then gradually expanded to the whole country. The cluster system groups 5-7 schools that are eographically close and accessible to each other in one cluster under the leadership of one of the principals known as a Cluster Centre Principal (CCP). The purpose of this study was to investigate the perceptions of CCPs of the implementation of the SCS in two clusters of a particular circuit in the Omusati region. It is a case study involving two CCPs, one serving Inspector of Education (IE), a former Inspector of Education, several teachers, principals and parents. Data were collected through interviews, document analysis, and focus group discussions. The study found that the practice of cluster leaders is informed by contemporary leadership and management thinking. The participatory approach employed in clusterbased committees enables site-based management and collaboration. This has led to organisational learning. It was also found that a number of challenges are hampering the implementation of the SCS. These include lack of system support and inadequate resources. However, the human potential coupled with a high degree of readiness exhibited by cluster members are seen as potential drivers of further development of the system. The study recommends the adoption of a national policy that formalises the SCS as well as the strengthening of system support to build cluster capacity. It also makes suggestions for further research in organisational culture and behaviour with the aim of developing leadership and management practices in the SCS.
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Willingness to pay for the control of water hyacinth in an urban environment of South Africa
- Authors: Law, Matthew Charles
- Date: 2008
- Subjects: Water hyacinth -- Control -- South Africa , Urban ecology (Sociology) -- South Africa , Biodiversity -- Economic aspects -- South Africa , Biodiversity conservation -- Economic aspects -- South Africa , Biological invasions -- Economic aspects -- South Africa , Biological invasions -- Environmental aspects -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:996 , http://hdl.handle.net/10962/d1002731 , Water hyacinth -- Control -- South Africa , Urban ecology (Sociology) -- South Africa , Biodiversity -- Economic aspects -- South Africa , Biodiversity conservation -- Economic aspects -- South Africa , Biological invasions -- Economic aspects -- South Africa , Biological invasions -- Environmental aspects -- South Africa
- Description: Water hyacinth is recognised as one of the most problematic invasive aquatic plant species in Africa. For this reason considerable funds are spent each year on itscontrol. As a consequence of the amount of money being spent on problems such as the invasion of water hyacinth, and because of the recognition of the ongoing and accelerated efforts that are required in the future, recent research has focused on accurately quantifying the costs and benefits of control of invasive species to aid policy decisions.A comprehensive cost-benefit analysis would be able to identify if the funds are justified and are being spent effectively. This thesis provides an example of a cost-benefit analysis of funds spent on the control of water hyacinth in an urban environment in South Africa. In order to develop a comprehensive assessment of the total economic value of the control of water hyacinth to an urban population, the Nahoon River in East London was selected as the study site to calculate the benefits of control. In addition to valuing the direct services provided by the resources that are traded in the market (in this case water provision), a contingent valuation study was undertaken in Abbottsford and Dorchester Heights (two suburbs in East London banking the Nahoon River). These were done in order to assess any non-use value a sample of 132 households of the population has for the control of water hyacinth, and any use values that are not traded in the market, for example recreational value. When the benefits of control of water hyacinth were compared to the costs of one of the least cost effective methods of control (herbicidal control), the benefits outweighed the costs by a ratio of more than 4:1, and for the most cost effective method of control the ratio was almost 6:1. These results provide a justification for the funds that are devoted to the control of water hyacinth, providing an argument for the continued expenditure for its control, and for further research into more cost effective methods of control, such as biological control.
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Investigating teaching strategies used by teachers to foster environmental learning in the Namibian Life Science curriculum
- Authors: Hoabes, Rosina
- Date: 2004
- Subjects: Life sciences -- Study and teaching -- Namibia Education -- Namibia Teaching -- Namibia Effective teaching -- Namibia Curriculum planning -- Namibia Educational change -- Namibia Environmental education -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1590 , http://hdl.handle.net/10962/d1003472
- Description: This study was carried out to investigate the strategies used by teachers to foster environmental learning in the Namibian Life Science curriculum in four schools in Swakopmund, Erongo Education Region. This study is a qualitative case study. I used semi-structured interviews, observation and document analysis as instruments to collect data. Two schools were selected to participate in the case study. Research participants included four teachers (two teachers from each school) of which two teachers are teaching at each school. The study was contextualised through a review of policy changes in Namibian education, which focus on learner-centred education. The study identified six strategies used by teachers to foster environmental learning in the Life Sciences curriculum. These are planning; working with information; practical, excursions and clubs; involving the learners; using visual aids and teaching materials; and choosing topics with a local focus. Through a consideration of the different strategies used by teachers, in relation to the learner-centred nature of the educational reform project in Namibia the study provides insight into the way in which teachers view learner-centred education. The study also illuminates how strategies used by teachers reflect learner-centred education principles and it outlines a number of tensions emerging in the fostering of environmental learning in learner-centred ways. The study identifies further support required by teachers, and makes recommendations which will further enhance the strategies used by teachers to foster the environmental learning focus in Life Sciences, and also enhance learner-centred teaching in Life Science.
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Alkane oxidation using metallophthalocyanine as homogeneous catalysts
- Authors: Grootboom, Natasha Denise
- Date: 2002
- Subjects: Oxidation , Alkanes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4449 , http://hdl.handle.net/10962/d1007794
- Description: Iron polychlorophthalocyanine (FePc(Cl)₁₆) and tetrasulfophthalocyanine ([M¹¹TSPc]⁴) complexes of iron, cobalt and manganese are employed as catalysts for the oxidation of cyclohexane using tert-butyl hydroperoxide (TBHP), chloroperoxybenzoic acid (CPBA) and hydrogen peroxide as oxidants. Catalysis using the FePc(Cl)₁₆ was performed in a dimethylformamide:dichloromethane (3 :7) solvent mixture. For the [Fe¹¹TSPc]⁴⁻, [Co¹¹TSPc]⁻ and [Mn¹¹TSPc]⁴⁻catalysts, a water:methanol (1:9) mixture was employed. The products of the catalysis are cyclohexanone, cyclohexanol and cyclohexanediol. The relative percentage yields, percentage selectivity and overall percentage conversion of the products depended on types of oxidant, or catalyst, concentrations of substrate or catalysts and temperature. TBHP was found to be the best oxidant since minimal destruction of the catalyst and higher selectivity in the products were observed when this oxidant was employed. Of the four catalysts investigated [Fe¹¹TSPc]⁴⁻ yielded the highest overall percentage conversion of 20%.The mechanism of the oxidation of cyclohexane in the presence of the FePc(Cl)₁₆ and [M¹¹TSPc]⁴⁻ involves the oxidation of these catalysts, forming an Fe(IlI) phthalocyanine species as an intermediate. Electrocatalysis using [Co¹¹TSPc]⁴⁻ as catalyst, employed an aqueous pH 7 buffer medium for electro-oxidation of 4-pentenoic acid. An enone is suggested as the only oxidation product of 4-pentenoic acid. No degradation of [Co¹¹TSPc]⁴⁻ was observed during the electrocatalytic process. In this process water was used as a source of oxygen therefore eliminating the production of by products from oxidant as in the case of TBHP and CPBA. This system was studied In an attempt to set up conditions for alkane electrocatalytic oxidation.
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South African memoirs in a decade of transition: Athol Fugard's Cousins (1994), J.M. Coetzee's Boyhood (1997), and Breyten Breytenbach's Dog Heart (1999)
- Authors: Roux, Christine Ann
- Date: 2002
- Subjects: Autobiography , Fugard, Athol , Coetzee, J. M., 1940 , Breytenbach, Breyten
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2191 , http://hdl.handle.net/10962/d1002233 , Autobiography , Fugard, Athol , Coetzee, J. M., 1940 , Breytenbach, Breyten
- Description: This thesis examines three South African memoirs using M. M. Bakhtin’s theories of the dialogical relationship in language and literature. By offering an alternative to a postmodern or multicultural interpretation of autobiographies, Bakhtin’s precepts, that define a dialogic, help to reframe a way of discussing memoirs and avoiding dead-ends previously arrived at by essayists in James Olney’s 1980 collection. Bakhtin’s ideas discussed here, which include the “once-occurrent moment”, “architectonic contraposition”, ”emotional-volitional tone”, “alibi”, “non-alibi”, and “centripetal” and “centrifugal” force, help to rebuild a discussion based on temporary and evolving self truth rather than fiction, the postmodern interpretation, or confession, the new-age secular spiritualism based on multicultural and politically correct standards. For this, each author’s memoir had to be examined separately and a conclusion was arrived at through inductive analysis. Rather than try to find similar characteristics, I focused on what made each memoir different and unique. Janet Varner Gunn’s Autobiography: Toward A Poetics of Experience (1982) refocused the debate over autobiography on process. The question, what steps did each author take toward writing about himself, led the discussion to an examination of the priorities each author exemplified. Beginning with Fugard who emphasized spatial, concrete, and sensory detail to help him contain his emotional life, the thesis moves on to an examination of Coetzee’s sense of justice. From the physical and intellectual world follows Breytenbach’s spiritual space-making. In each memoir, control of space is evident on different levels of experience. Articulating space inevitably leads to a discussion of boundaries. Here, Charles Taylor’s emphasis on the modern self’s need to articulate a horizon or a framework is helpful in generalizing the effect of the autobiographical process. The conclusion reached is that autobiography is inherently centrifugal: it moves away from the center of cultural thinking because its “truth” bolsters itself on dialogical process which does not depend on a fixed authority but rather on communicative exchange. As an example of exchange, autobiography’s central truth is that it returns to a “unique point of origin”, namely the self, only to reconnect to the other in a potentially eternal exchange of responsiveness moving away from the center.
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A Zulu martyr? What are the factors that led to the sparse and irregular public commemoration of Maqbamusela Kbanyile in the Lutheran church to which he belonged?
- Authors: Nürnberger, Margarete Paula Luise
- Date: 2001
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:21087 , http://hdl.handle.net/10962/6301
- Description: From Foreword: About a fortnight after I had submitted the thesis on factors that lead to the sparse and irregular public commemoration of Maqhamusela Khanyile in the Lutheran church to which he belonged when the archivist of the Norwegian Mission Society in Stavanger sent an e-mail that new material had been found. It consisted of a miscellany of various documents connected with the erection of the first cross, dating from 1926-1940, to be found in Misjonskapets archiv SA, boks nr. 2A legg nr. 8. The new material falsified two hypotheses on which the thesis had worked. The first of these hypotheses states that the initiative for the erection of the first monument to Maqhamusela had come from the Anglican interest in and research on him in 1935. Source 1a in the new material proves that in 1926 there were already appeals for contributions towards such a monument among the Lutheran congregations that grew out of the Norwegian work. The second hypothesis falsified by the new material had issued from memories of interviewees (e.g. Dean Shobete in interview 33) which stated that a stone with the Zulu inscription had been placed in the saddle of the hill where the execution had taken place before the erection of the first cross. The new material proves that the suggestion for a marble plate dates from 1927 (source 2a) and that the slab was eventually ordered in October 1939. A receipt (document 10) for "making the Maqhamusela monument" is dated 11.5.1940. Altogether, then, there was earlier commemoration of Maqhamusela in the church of which he was a member than the thesis had found, and the impetus to erect a monument had come from White and some black Norwegian Lutherans themselves.
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The effect of different parameters on the rupture properties of leather in a tensile test
- Authors: Makhothe, Kelebohile
- Date: 1998
- Subjects: Leather -- Testing
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5462 , http://hdl.handle.net/10962/d1005247 , Leather -- Testing
- Description: This thesis explores the effect of some parameters on the breaking strain, strength and the shape of the stress-strain curve of bovine leather as revealed by uniaxial tensile tests. The parameters explored are fatliquoring, moisture content, strain rate and cyclic stressing. A basic mechanical model of a simple two-dimensional weave is created and used to describe the effect of such a weave on the shape of the stress-strain curve. It is found that fatliquoring lubricates and opens up the fibre structure and thereby makes the weave more extensible. The increase in the extensibility depends on the direction in which samples are cut and therefore the manner in which the fibres are orientated. Patliquoring is observed to increase the degree to which fibres pull out at break. There are indications that the strength of fatliquored leather decreases with time of storage, while the extensibility increases. The effect of the strain rate on the breaking strain, the tensile strength and the shape of the stress-strain curve is not very clear. The stressing and releasing leather decreases the strength of leather when the fibres are orientated preferentially along the direction of the applied stresses, but has an insignificant effect in the transverse direction. It is concluded that the degree of lubrication in a weave and the orientation of the fibre bundles significantly influence the performance of leather in a test. Both moisture and fatliquoring lubricate the weave. In both the cases the degree of fibre adhesions in a weave is decreased. A well lubricated weave allows its constituent fibres to slide and align along the direction of the applied stresses, and this tends to occur before the fibres themselves areextended. Cyclic testing, at low strains, ruptures fibre adhesions and as a result induces permanent set and makes a hide softer. Most of the work done in breaking the fibre adhesion is done in the first cycle.
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Interactions between ants, herbivorous insects and bracken (Pteridium aquilinum), a fern with extrafloral nectaries
- Authors: Rashbrook, Vanessa Karin
- Date: 1989
- Subjects: Arthropod pests -- South Africa Ants -- South Africa Ferns -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5592 , http://hdl.handle.net/10962/d1002042
- Description: Bracken (Pteridium aquilinum) is a cosmopolitan species of fern which possesses extrafloral nectaries. A survey of the arthropod fauna associated with the plant throughout its range in South Africa identified the most widespread and damaging bracken herbivores and those species most likely to be influenced by ants visiting the extrafloral nectaries. Seventeen herbivorous arthropods were found to be definitely feeding on bracken and a further thirteen species with a less certain status were recorded. In addition, several species of ants were observed on the fronds and feeding at the extrafloral nectarie. On the basis of their widespread distribution and abundance, four bracken herbivores emerged as being particularly detrimental to the plant in South Africa. They were an eriophyid gall mite, a leafhopper and two moths. The biology of the two lepidopterans, Appana cinisigna and Panotima sp., suggested that they were potentially vulnerable to ants at various stages of their life histories. Laboratory experiments were undertaken to observe ant-lepidopteran interactions under controlled conditions. The ant Crematogaster peringueyi rapidly removed exposed A. cini igna eggs, but did not appear to regard Panotima eggs as food items. Small instar larvae of both species proved vulnerable, but the larger larvae appeared capable of escaping ant predation. Ant exclusion experiments in the field, using natural and artificially augmented ant densities, were carried out at two sites near Grahamstown. The dominant ant species was C. peringueyi. Neither the numbers of lepidopterans nor levels of herbivory were significantly reduced by the presence of ants . Despite the implications of the laboratory tests, the results of these field experiments did not support the hypothesis that ants which visit bracken extrafloral nectaries benefit the plant. Ant-bracken field studies on other continents also reported no significant ant-related effects, though marginal reductions in the abundance of certain herbivores have been noted at one site in the U.K. Since ant protection does not appear to be an inevitable consequence of having extrafloral nectaries, their value to bracken is in some doubt. The most likely situation where effective protection will occur is when high densities of vulnerable herbivores are preyed upon by large numbers of aggressive ants. However, even under these conditions, enhancement of plant fitness is not inevitable. This raises the question of why extrafloral nectaries have been retained in a plant that is as successful and widespread as bracken.
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Isolation, purification and effect of ligands on the nicotinic cholinergic receptor
- Authors: Kapp, Eugene Anthony
- Date: 1989
- Subjects: Ligands (Biochemistry) , Nicotinic receptors
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4550 , http://hdl.handle.net/10962/d1018235
- Description: The nicotinic cholinergic receptor protein of the fish electric organ, Torpedo fuscomaculata, has been isolated, purified and shown to represent a true model for the nAChR from other species and higher vertebrates. It is an integral membrane protein composed of four different subunits, tightly associated with other functional, but non-specific proteins. Purification of the nicotinic cholinergic receptor by chromatofocusing demonstrates an improved method over that of affinity and ion-exchange chromatography. Gel chromatography and SDS-polyacrylamide gel electrophoresis show evidence of four subunits; a(40-44 kDa), 6(53 kDa ),'Y(63 kDa) and 6(66 kDa) despite some degradation of receptor molecules by intracellular proteases. Spectrophotometric and fluorimetric studies of receptor-ligand interactions, show the functional and chemical integrity of the receptor to remain intact after solubilisation. The effect of cholinergic ligands on purified receptor preparations indicate quenching of the intrinsic fluorescence of the receptor. Agonists, like acetylcholine, bind and cause local conformational transitions, changing the active region from a hydrophobic to a hydrophilic environment. This phenomenon is illustrated by the 10-fold increase in fluorescence when the receptor is in a desensitised state. Antagonists, such as d-Tubocurarine, block this conformational transition. In vitro rectus abdominis muscle preparations . show the nitrosamines, dimethylnitrosamine and diphenylnitrosamine, to be true agonists of the nAChR. However their low affinity and specificity for the receptor precludes them as photoaffmity labelling agents. Photoactivation of dimethylnitrosamine occurs when associated with an acidic hydrogen at the active site of the receptor, suggesting energy-transfer labelling to be more facile than photoaffmity labelling. The membrane-bound receptor, in the presence of these nitrosamines, undergoes conformational transitions regulating the opening and closing of the ion-channel. Desensitisation and receptor activation are shown to involve one and the same molecular transition.
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Self-concept as a measure of success in the military environment
- Authors: Besener, Paul Robert
- Date: 1987
- Subjects: Self-perception , Control , Recruits , Soldiers , Military , National service , South Africa , Pupils , Learners , Guidance , School curriculum
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: vital:1363 , http://hdl.handle.net/10962/d1001429
- Description: This piece of research is an attempt to evaluate the relationship between military 'success' and the psychological preparedness of recruits in terms of their self-concepts and locus of control orientations. The new recruit is forced to adapt to the military environment which will, in turn, attempt to change him into an effective soldier. It was noticed by the researcher, who was involved in military training at the time, that a number of recruits, even some with seemingly limited potential, coped well, while others who seemed to have the ability failed to cope adequately. Recruits completed questionnaires which provided the researcher with biographical data and background information. In addition, the Bledsoe Self-Concept Scale and the Nowicki and Strickland Locus of Control Scale were used in order to determine their self-concepts and locus of control orientations respectively, prior to the beginning of national service. Detailed unstructured interviews were also conducted with a sample of military personnel, to provide another basis for gathering data and for clarifying some of the issues involved. Briefly, the chief conclusion of this researcher is that a significant majority of 'successful' recruits in the military environment have a positive self-concept and an internal locus of control. On the basis of the above finding, it is suggested that there is a need to guide pupils about certain aspects of military life before they begin their National Service. There would seem to be a need for this guidance to be incorporated into the school curriculum, together with such practical aspects as cadets, shooting, etc. There is a shortage of this kind of research on the military situation in South Africa, and it is suggested that numerous issues in this field need to be researched for the benefit of future conscripts and the military alike.
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Labour migration, marriage and family life in a Ciskei village
- Authors: Manona, Cecil Wele
- Date: 1981
- Subjects: Migrant labor -- Social aspects -- South Africa -- Ciskei
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2107 , http://hdl.handle.net/10962/d1006884
- Description: From introduction: The aim of this thesis is to describe and analyse the effects of labour migration on marriage and family life. The field material is from Burnshill, a village situated in the Keiskammahoek district in the Ciskei. Keiskammahoek is bounded on the East by the districts of King William's Town and Stutterheim, on the West and South by Middledrift and on the North by Cathcart. The inhabitants of Burnshill are overwhelmingly Xhosa and Mfengu (the main ethnic groups in the Ciskei) but also include a small proportion of people whose clans are of Mpondo and Thembu origin. This village has undergone extensive change. As we shall show later, it was settled de novo by the Mfengu and the Xhosa during the second half of the past century. This is one of the reasons why it lacks the homogeneity and continuity of cultural tradition which are predominant features of long-established communities.
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"Holy baptism" : a reconsideration of the doctrine of holy baptism in the light of recent research
- Authors: Moore, Robert Humphrey
- Date: 1974
- Subjects: Baptism in the Holy Spirit , Holy Spirit -- Biblical teaching
- Language: English
- Type: Thesis , Bachelor , BDiv
- Identifier: vital:1239 , http://hdl.handle.net/10962/d1007686 , Baptism in the Holy Spirit , Holy Spirit -- Biblical teaching
- Description: Conclusion: This study has helped us to perceive the significance of Christian Baptism as it arose from its antecedents, and yet differed decisively from them in meaning and significance. We have seen how Baptism grew from the New Testament situation into the life of the Early Church. We have considered the sacramental nature of Baptism, that here, while the Community is visibly active, in this holy sacrament, God is the doer of what is done. It is by Him, whose Grace is seen in Jesus Christ, that we are brought to new life within the Community of His Covenant and what He can do for adults, He can do for infants as well. However, it is good for us to remember that His presence is also for our judgement, and that there therefore remains upon us as individuals and as Community the requirement of faith and faithfulness. We have seen how it is that the Holy Spirit is given in Baptism, and we believe it is through His indwelling presence and power that we are able to come into the Family of God and enjoy that fellowship with Him, which is salvation. We have also seen that, despite many centuries of thought and study, no final doctrinal definition of Baptism is yet achieved, and that the Churches are still giving this serious attention.
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