Catalytic activities of metallophthalocyanines towards detection and transformation of pollutants
- Authors: Agboola, Bolade Oyeyinka
- Date: 2007
- Subjects: Phthalocyanines Electrochemistry Pollutants -- Biodegradation Pollutants -- Measurement
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4427 , http://hdl.handle.net/10962/d1006922
- Description: Syntheses, spectral, electrochemical and spectroelectrochemical studies of new thiol-derivatised MPc complexes were satisfactorily carried out. For the first time, spectroelectrochemistry gave evidence for the formation of Ni²⁺/Ni⁺ process in a NiPc complex. Significant insights as to the nature of Fe⁺Pc and Ni⁺Pc spectra were obtained. Transformations of chlorophenols using chemical and photochemical methods are presented. For cobalt tetrasulphophthalocyanine catalysed oxidation of chlorophenols using hydrogen peroxide as the oxidant, types of oxidation products formed depended on the solvent conditions. Photolysis of aqueous solutions of chlorophenols in the presence of immobilised non-transition metal phthalocyanine photosensitisers onto Amerlite® was carried out. For the first time, MPcS[subscript mix] complexes were immobilised on Amberlite® for use in heterogeneous photocatalysis. Photolysis of the chlorophenols resulted mainly in the formation of chlorobenzoquinone derivatives. The generation of singlet oxygen (¹O₂) by these immobilised MPc photosensitisers was found to play a major role in their photoactivities. Modifications of gold electrodes with the newly synthesised thiol-derivatised MPc complexes via electropolymerisation and SAM techniques are presented. Cyclic voltammetry, impedance spectroscopy (NiPcs only) and spectroelectrochemical techniques (NiPcs only) confirmed that the complexes formed films on gold electrodes. Stable and well packed SAM films as evidenced by the voltammetric characterisation were obtained. For the first time, optimisation of the time for SAM formation based on CV technique was studied. First example of a formation of MnPc-SAM was achieved. Catalytic activities of the NiPc towards chlorophenol depended on the nature of the NiPc in the polymer films and also anti-fouling ability of the films depended on polymer film thickness. The FeTBMPc polymer modified gold electrode showed the best catalytic activity in terms of peak potential, E[subscript p] when compared to reported work in literature for nitrate electrooxidation. Cyclic voltammetry and spectroscopy studies showed that the CoPcs, FePcs and NiPcs catalysed nitrite oxidation involve 2 electrons in total while that of McPcs involve 1 electron. Better catalytic performance towards sulphite electrooxidation were obtained for the CoPcs, FePcs and MnPcs which have metal based redox processes within the range of the sulphite electrooxidation peak while the NiPcs which did not show metal based oxidation reaction performed less.
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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.
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Transcending state-centrism: new regionalism and the future of Southern African regional integration
- Authors: Blaauw, Lesley
- Date: 2007
- Subjects: Southern African Development Community Southern African Customs Union Southern African Development Coordination Conference Regionalism -- Africa, Southern Africa, Southern -- Economic integration
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2761 , http://hdl.handle.net/10962/d1002971
- Description: This dissertation argues that in the 1990s and beyond, the character and functions of regions and regionalism have experienced a major transformation. This requires a reconceptualisation of regions and regionalism that transcends state-centrism. The argument here is that the definition of regions and regionalism needs to recognise that other actors also participate in the construction of regions and the practise of regionalism. Up to now, however, theories of integration incompletely deal with outcomes appropriate to developing countries, states and regions. In the context where people remain vulnerable to top-down forms of regionalism driven by the forces of globalisation, this calls for a new approach in the analytical study of regionalism in a transnational context. The contention is that new regionalism, and its variant, developmental regionalism pay attention to the role those organised civil society actors and those marginalised by both globalisation and regionalisation play in promoting regionalism in a transnational context. Historically, state-centric regionalism in southern Africa was not aimed at achieving developmental objectives. In the case of SACU, the argument is that South Africa used its economic strength in a hegemonial way. To counter-act apartheid South Africa’s economic hegemony, SADCC was formed. SADCC achieved limited success in the fields of infrastructural development and in attracting donor aid. The end of the Cold War and the downfall of apartheid compelled these organisations to recast their objectives and purpose. For SACU this meant changing from an organisation dominated by South Africa to a fully-fledged inter-state one. Disconcertedly, however, about the reforms undertook by SACU, is that the disposition of member states remain important in determining the content and scope of regionalism. SADC, on the other hand, has also not sufficiently reform itself to achieve the ambitious goals it set-out for itself. Moreover, while SADC has since its inception in 1992 set-out to involve non-state actors in its regional integration efforts, limited institutional reform in 2000 and beyond, and elites at the forefront of institutional restructuring make it difficult for non-state actors to contribute to sustainable regional integration. In conclusion, this dissertation maintains that sustainable regionalist orders are best built by recognising that beyond the geometry of state-sovereignty, civil society organisations with a regional focus and the ordinary people of the region also contribute to regioness and as such to the re-conceptualisation of regional community in southern Africa.
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Spermiogenesis, sperm ultrastructure and reproductive tract morphology in cicadas implications for systematic relationships
- Authors: Chawanji, Abraham Simbarashe
- Date: 2007
- Subjects: Cicadas Cicadas -- Reproduction Spermiogenesis in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5770 , http://hdl.handle.net/10962/d1005458
- Description: Sperm structure in five species of cicadine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis, P. hirtipennis and Pycna semiclara) and five species of cicadettine cicadas (Melampsalta leucoptera, Quintilia walkeri, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) was investigated by light and electron microscopy. In addition, spermiogenesis in cicadas was described; the information was derived from two cicadettines (Diceroprocta biconica and M. matoposa) and three cicadines (Kongota punctigera, P. capensis and P. semiclara). Mature spermatozoa of all species investigated are elongate and filiform, consisting of three distinct regions: the head (acrosome and nucleus), mid-piece and tail. All species produce more than one discrete length of nucleated, motile sperm, a form of sperm polymorphism termed polymegaly. Polymegaly is expressed in three ways; sperm have uni-, bi- or trimodal nucleus and tail lengths. Besides the differences in length, there are also notable differences in the size of nuclei. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming spermatodesmata. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with a tubular substructure and a subacrosomal space. The anterior of the nucleus intrudes into the posterior section of the subacrosomal space. Anteriorly the acrosome is laterally flattened; posteriorly it extends as two tubular processes on either side of the nucleus that gradually decrease in diameter. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the putative centriolar adjunct which does not form in close proximity to the centriole and hence may not be a true centriolar adjunct. The lamellate disposition of the centriolar adjunct material within the sperm-midpiece of cicadettine cicadas is distinct, and separates these cicadas from their cicadine counterparts in which the centriolar adjunct material is non-lamellate. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. Except for size the architecture of short and long spermatozoa is generally similar in all species. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely related. Only long nuclei were observed in the fertilized eggs of A. zuluensis indicating that sperm with long nuclei might be favoured for fertilization. Spermiogenesis involves: (a) development of the acrosome from a proacrosomal granule; (b) development of the nucleus, characterized by elongation and streamlining with a simultaneous condensation of chromatin; (c) development of the axoneme from the centriole; (d) amalgamation of individual small mitochondria to form elongated mitochondrial derivatives in which cristae are arranged into regularly spaced lamellae; and (f) elimination of cytoplasm. The presence of a manchette, a transient microtubular organelle, which surrounds the acrosome, nucleus and mitochondrial derivatives, is a characteristic feature of spermiogenesis. The gross morphology of the reproductive tract in both male and female cicadas exhibits an organization similar to that in most oviparous insects. The non-functional spermatheca is the only exceptional feature in the female reproductive tract. Its role has been taken over by the common oviduct which, subsequently, has become modified into a swollen, differentiated structure with a dual role of receiving oocytes from the paired ovaries and storage of spermatozoa. Testis mass varies between cicada species; this variation might be linked to the intensity of sperm competition which has been found to be positively correlated with relative investment in spermatogenesis. Based on the preliminary findings of this study, K. punctigera, with its larger testis relative to body size, would be the ideal candidate to show the greatest levels of sperm competition. Accessory glands in both male and female A. zuluensis, D. biconica, P. hirtipennis and O. quadraticollis are very long; this character might be of phylogenetic significance. Despite being notoriously refractory spermiocladistics is potentially valuable in systematic and phylogenic studies of cicadas, especially at the subfamily level.
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A study of the summarizing strategies used by ESL first year science students at the University of Botswana
- Authors: Chimbganda, Ambrose Bruce
- Date: 2007
- Subjects: English language -- Study and teaching (Foreign speakers) -- Botswana English language -- Study and teaching (Higher) -- Botswana Science -- Study and teaching (Higher) -- Botswana Language and education -- Botswana College students -- Botswana -- Language
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2341 , http://hdl.handle.net/10962/d1002623
- Description: One of the major problems faced by speakers of English as a second language (ESL) or non-native speakers of English (NNS) is that when they go to college or university, they find themselves without sufficient academic literacy skills to enable them to navigate their learning successfully, such as the ability to summarize textual material. This thesis examines the summarizing strategies used by ESL first year science students at the University of Botswana. Using multiple data collection methods, otherwise known as triangulation or pluralistic research, which is a combination of quantitative and qualitative methods, one hundred and twenty randomly sampled students completed questionnaires and summarized a scientific text. In order to observe the students more closely, nine students (3 high-, 3 average- and 3 low-proficiency) were purposively selected from the sample and wrote a further summary. The nine students were later interviewed in order to find out from them the kinds of strategies they had used in summarizing the texts. To obtain systematic data, the summaries and the taped interview were coded and analyzed using a hybrid scoring classification previously used by other researchers. The results from the Likert type of questionnaire suggest that the ESL first year science students are 'aware' of the appropriate reading, production and self-assessment strategies to use when summarizing. However, when the data from the questionnaire were cross-checked against the strategies they had used in the actual summarization of the text, most of their claims, especially those of the low-proficiency students, were not sustained. As a whole, the results show that high-proficiency students produce more accurate idea units and are more capable of generalizing ideas than low-proficiency students who prefer to "cut and paste" ideas. There are also significant differences between high- and low proficiency students in the manner in which they decode the text: low-proficiency students produce more distortions in their summaries than high-proficiency students who generally give accurate information. Similarly, high-proficiency students are able to sort out global ideas from a labyrinth of localized ideas, unlike average- and low-proficiency students who include trivial information. The same trend is observed with paraphrasing and sentence combinations: high-proficiency students are generally able to recast and coordinate their ideas, unlike low-proficiency students who produce run-on ideas. In terms of the discrete cognitive and meta-cognitive skills preferred by students, low proficiency students are noticeably unable to exploit pre-summarizing cognitive strategies such as discriminating, selecting, note-making, grouping, inferring meanings of new words and using synonyms to convey the intended meanings. There are also greater differences between high- and low-proficiency students when it comes to the use of meta-cognitive strategies. Unlike high-proficiency students who use their reservoir of meta-cognitive skills such as self-judgment, low-proficiency students ostensibly find it difficult to direct their summaries to the demands of the task and are unable to check the accuracy of their summaries. The findings also show that some of the high-proficiency students and many average- and low-proficiency students distort idea units, find it difficult to use their own words and cannot distinguish between main and supporting details. This resulted in the production of circuitous summaries that often failed to capture the gist of the argument. The way the students processed the main ideas also reveals an inherent weakness: most students of different proficiency levels were unable to combine ideas from different paragraphs to produce a coherent text. Not surprising, then, there were too many long summaries produced by both high- and low-proficiency students. To tackle some of the problems related to summarization, pre-reading strategies can be taught, which activate relevant prior knowledge, so that the learning of new knowledge can be facilitated. During the reading process students can become more meta-cognitively aware by monitoring their level of understanding of the text by using, for example, the strategy suggested by Schraw (1998) of "stop, read and think". Text analysis can also be used to help the students identify the main themes or macro-propositions in a text, and hence gain a more global perspective of the content, which is important for selecting the main ideas in a text. A particularly useful approach to fostering a deeper understanding of content is to use a form of reciprocal or peer-mediated teaching, in which students in pairs can articulate to each other their understanding of the main ideas expressed in the text. As part of the solution to the problems faced by students when processing information, we need to take Sewlall's (2000: 170) advice that there should be "a paradigm shift in the learning philosophy from content-based to an emphasis on the acquisition of skills". In this regard, both content and ESL teachers need to train their students in the explicit use of summarizing strategies, and to plan interwoven lessons and learning activities that develop the learners' intellectual ways of dealing with different learning problems so that they can make learning quicker, easier, more effective and exciting.
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The microbial ecology of sulphidogenic lignocellulose degradation
- Authors: Clarke, Anna Maria
- Date: 2007
- Subjects: Microbial ecology , Lignocellulose , Sulfides , Lignin , Lignocellulose -- Biodegradation , Mines and mineral resources -- Waste disposal , Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4094 , http://hdl.handle.net/10962/d1008181
- Description: Acid mine drainage is a well known environmental pollutant, not only in South Africa, but throughout the world, and the use of microbial processes in the treatment of these wastes has been the subject of investigation over past decades. Lignocellulose packed-bed reactors have been used in passive treatment systems, and, although effective initially, they show early decline in performance while the packing material remains largely un-utilized. Little is known about this phenomenon which remains a severe constraint in the development of efficient passive mine water treatment systems. It has been proposed that the degradation pathways of the complex lignocellulose substrate may be limited in some way in these systems during the manifestation of this effect. This study has addressed the problem using a molecular microbial ecology methodology in an attempt to relate trophic functions of the microbial population to the physico-chemical data of the system. A field-scale lignocellulose packed-bed reactor located at Vryheid Coronation Colliery (Northern Kwa-Zulu Natal province, South Africa) was monitored for six years and the results showed the classic profile of performance decline related to a slowdown in sulphate reduction and alkalinity production. The reactor was decommissioned , comprehensive samples were collected along the depth profile and the microbial populations investigated by means of 16S rRNA gene methodology. The population was found to include cellulolytic Clostridia spp., CytophagaIFlavobacterlBacteroidetes, Sphingomonadaceae and as yet uncultured microorganisms related to microbiota identified in the rumen and termite gut. These are all known to be involved as primary fermenters of cellulose. Oesulphosporosinus was present as sulphate reducer. A comparison of substrata sampling and population distribution suggested that spatial and temporal gradients within the system may become established over the course of its operation. Based on these findings, a laboratory-scale reactor was constructed to simulate the performance of the packed-bed reactor under controlled experimental conditions. The laboratory-scale reactor was operated for 273 days and showed comparable performance to that in the field in both biomolecular and physicochemical data. Clearly defined trophic niches were observed. These results suggested that a sequence of events does occur in lignocellulose degradation over time. Based on the spatial and temporal column studies, a descriptive model was proposed to account for these events. It was found that fermentative organisms predominate in the inlet zone of the system using easily extractable compounds from the wood, thus providing feedstock for sulphate reduction occurring in the succeeding compartments. Production of sulphide and alkalinity appears to be involved in the enhancement of lignin degradation and this, in turn, appears to enhance access to the cellulose fraction. However, once the readily extractables are exhausted, the decline in sulphide and alkalinity production leads inexorably to a decline in the overall performance of the system as a sulphate reducing unit operation. These observations led to the proposal that with the addition of a limited amount of a readily available carbon source, such as molasses, in the initial zone of the the reactor, the ongoing generation of sulphide would be sustained and this in turn would sustain the microbial attack on the lignocellulose complex. This proposal was tested in scale-up studies and positive results indicate that the descriptive model may, to some extent, provide an account of events occurring in these systems. The work on sustaining lignocellulose degradation through the maintenance of sulphate reduction in the initial stages of the reactor flow path has led to the development of the Degrading Packed-bed Reactor concept and that, has subsequently been successfully evaluated in the field.
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Opportunity and constraint : historicity, hybridity and notions of cultural identity among farm workers in the Sundays River Valley
- Authors: Connor, Teresa Kathleen
- Date: 2007
- Subjects: Agricultural laborers -- South Africa -- Relocation Addo Elephant National Park (South Africa) Xhosa (African people) -- South Africa -- Eastern Cape -- Ethnic identity Forced migration -- South Africa -- Eastern Cape Land settlement -- South Africa -- Government policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2117 , http://hdl.handle.net/10962/d1008367
- Description: This thesis focuses on relationships of opportunity and constraint among farm workers in the Sundays River Valley (SRV), Eastern Cape Province. Relationships of 'constraint' include those experiences of displacement and forced removal and war, including forced removals by the apartheid state in 1960 and 1970. Relationships of 'opportunity' include the ways in which residents in the SRV have contested their experiences of upheaval and domination, and the formation of a regional sense of place and belonging/ investigate how farm workers actually draw elements of locality and identity from their experiences of upheaval, and how displacement bolsters feelings of belonging and place. Instead of viewing displacement as a once-off experience, this thesis investigates displacement in historical terms, as a long-term, 'serial' experience of human movement, which is continued in the present- specifically through the creation of the Greater Addo Elephant National Park. I concentrate on developing a spatialised and cultural notion of movemenUplacement. 'Place' is investigated as a term that refers to rather indeterminate feelings of nostalgia, memory and identity, which depend on a particular connection to territory (ie: 'space'). I emphasise that elements of place in the SRV are drawn from and expressed along dualistic lines, which juxtapose situations of opportunity and constraint. In this way, farm workers' sense of connection to farms and ancestral territory in the SRV depends on their experiences of stable residency and work on farms, as well as their memories of removal from land in the area. I emphasise that those elements of conservatism (expressed as 'tradition' and Redness) among Xhosa-speaking farm workers are indications of a certain hybridity of identity in the region, which depend on differentiation from other groups (such as so-called 'coloured' farm workers and 'white' farmers), as well as associations between these groups. This thesis lays emphasis upon those less visible and definable 'identities' in the Eastern Cape Province, specifically by shifting focus away from the exhomeland states of the Ciskei and Transkei, to more marginal expressions of identity and change (among farm workers) in the Province. I point out that labourers cannot solely be defined by their positions as farm workers, but by their place and sense of cultural belonging in the area. In this sense, I use the idea of work as a loaded concept that can comment on a range of cultural attitudes towards belonging and place, and which is firmly embedded in the private lives of labourers - beyond their simple socio-economic conditions of farm work. I use Bourdieu's conception of habitus and doxa to define work as a set of dispositions that have been historicised and internalised by workers to such an extent, that relationships of domination are sometimes inadvertently obscured through their apparent 'naturalness'. Moreover, I point out that work can be related to ritualised action in the SRV through the use of performance and practice-based anthropological theory. Both work and ritual are symbolic actions, and are sites of struggle within which workers express themselves dualistically. Rituals, specifically, are dramatic events that combine disharmonious and harmonious social processes - juxtaposing the powerlessness of workers (on farms), and the deep sense of belonging and place in the SRV. I argue that the deep historical connections in the SRV have largely been ignored by conservationists in the drive to establish new protected zones (such as the Greater Addo Elephant National Park), and that a new model of shared conservation management is needed for this Park.
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Masculinity, citizenship and political objection to compulsory military service in the South African Defence Force, 1978-1990
- Authors: Conway, Daniel John
- Date: 2013-08-15
- Subjects: Conscientious objectors -- South Africa End Conscription Campaign (South Africa) National service -- South Africa Draft -- South Africa South Africa -- Military policy Masculinity -- South Africa South Africa. South African Defense Force Gays in the military -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2601 , http://hdl.handle.net/10962/d1008383
- Description: This thesis conceptualises compulsory military service and objection to it as public performative acts that generate gendered and political identity. Conscription was the primary performance of citizenship and masculinity for white men in apartheid South Africa. Conscription was also a key governance strategy both in terms of upholding the authority of the state and in engendering discipline in the white population. Objection to military service was therefore a destabilising and transgressive public act. Competing conceptualisations of masculinity and citizenship are inherent in pro and anti-conscription discourses. The refusal to undertake military service places men outside the accepted means of graduating to ' real' manhood and patriotic citizenship. Although objection can be an iconic and transgressive act, objectors have an essentially ambivalent subjectivity in the public realm. Objectors are 'strangers' in a socially constructed and gendered binary of 'insiders' and 'outsiders' . This ambivalent status creates opportunities but also constraints for the performance of objection. The thesis analyses the effectiveness of objectors' performances and argues that there is a distinction between a radical challenge to hegemonic conceptions of militarised masculinity and citizenship and assimilatory challenges. The tension between radicalism and assimilation comes to the fore in response to the state's attacks on objectors. The militarised apartheid state is defined as not only masculine but heteronormative terms and it is the deployment of sexuality that is its most effective means of stigmatising and restricting the performance of objection. The thesis uses interview material, archival data and case studies and concludes that objectors (and their supporters) weaved multiple narratives into their performances but that as the 1980s progressed, the performance of objection to conscription became assimilatory and this demonstrates the heteronormativity of the state, military service and the public realm. , KMBT_363 , Adobe Acrobat 9.54 Paper Capture Plug-in
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Management of invasive aquatic weeds with emphasis on biological control in Senegal
- Authors: Diop, Ousseynou
- Date: 2007
- Subjects: Aquatic weeds -- Biological control -- Senegal Invasive plants -- Biological control -- Senegal Aquatic plants -- Biological control -- Senegal
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5728 , http://hdl.handle.net/10962/d1005414
- Description: In 1985 the Diama Dam was built near the mouth of the Senegal River to regulate flows during the rainy season and prevent the intrusion of seawater during the dry season. This created ideal conditions upstream of the dam wall for invasion by two highly invasive aquatic weeds, first by water lettuce Pistia stratiotes Linnaeus (Araceae) in 1993, and then by salvinia Salvinia molesta D.S. Mitchell (Salviniaceae) in 1999. This study was focused on the management of P. stratiotes and S. molesta. Following successes that were achieved elsewhere in the world, biological control programmes involving two weevil species were inaugurated against both weeds and research was focused on several aspects. These included pre-release studies to determine the weevils' host-specificity and impact on the plants in the laboratory, their subsequent mass-rearing and releases at selected sites and post-release evaluations on their impact on the weed populations in the field. Both programmes, which reprepresented the first biocontrol efforts against aquatic weeds in Senegal, proved highly successful with severe damage inflicted on the weed populations and complete control achieved within a relatively short time span. A laboratory exclusion experiment with N. affinis on P. stratiotes showed that in treated tubs, the weevil strongly depressed plant performance as measured by the plant growth parameters: mass, rosette diameter, root length, number of leaves and daughter plants whereas control plants were healthy. Field releases started in September 1994 and water coverage by P. stratiotes at Lake Guiers was reduced by 25% in January 1995 and 50% in April 1995. A general decline of 65% in water coverage by P. stratiotes was observed in June 1995 and by August 1995, eight months after releases P. stratiotes mats were destroyed. Further, although no releases were made there, good results were obtained within 18 months at Djoudj Park water bodies, located 150 km NW from Lake Guiers indicating the potential of the weevil to disperse long distances. In 2005, P. stratiotes reappeared and the weevil N. affinis has located and controlled all of these P. stratiotes recurrences after new releases. In 1999, S. molesta covered an estimated area of 18 000 ha on the Senegal River Left Bank and tributaries (Senegal) and 7 840 ha on the Senegal River Right Bank (Mauritania). Military and Civil Development Committee (CCMAD) and community volunteers made an effort to control S. molesta using physical removal, but this costly and labour-intensive approach was unsustainable. Hence, biological control was adopted by Senegal and Mauritania to manage the weed. Host range tests to assess feeding by C. salviniae on S. molesta and non-target plants and carried out on 13 crop species showed that no feeding damage was observed on the latter and weevils only fed on S. molesta. Field releases of some 48 953 weevils at 270 sites were made from early January 2002 to August 2002. Within one year, weevils were established and were being recovered up to 50 km from the release sites. In a case study conducted at one of the release sites, the S. molesta infestation was reduced from 100% to less than 3% 24 months after release. These results are discussed in the context of the weeds’ negative impact on aquatic systems and riverside communities, and in the involvement of these communities in the programmes.
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Camphor-derived chiral auxiliaries: a synthetic, mechanistic and computational study
- Authors: Duggan, Andrew Robert
- Date: 2007
- Subjects: Camphor Chirality Asymmetric synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4415 , http://hdl.handle.net/10962/d1006772
- Description: A broadly based approach has been undertaken to the development and use of camphor derivatives as chiral auxiliaries in asymmetric synthesis – an approach which has embraced synthetic, mechanistic and computational studies. The unambiguous characterization of mono- and dihydroxy-derivatives, obtained by reduction of chiral camphor ether dimers, has been achieved through detailed one- and two-dimensional NMR spectroscopic analysis. The resulting data has been used to establish both the regio- and stereochemistry of the hydroxyl groups. A camphor-derived cyclic iminolactone has been shown to provide a convenient platform for the synthesis of chiral α-amino acids, stereoselective monoalkylation of the iminolactone affording a range of products in yields of 52 - 65 % with up to 85 % d.e. The attempted development of chiral bifunctional Morita-Baylis-Hillman substrates has revealed an unexpected equilibration between isomeric bornane 2,3-diol monoacrylates via acid-catalysed intramolecular transesterification. A detailed [superscript 1]H NMR-based kinetic study of the rearrangement in various media and at various temperatures has permitted the determination of the kinetic and thermodynamic parameters. A computational study at the DFT level has been used to explore the potential energy surfaces of the acid-catalysed and uncatalysed transesterification of the monoacrylate esters. The theoretical data supports the involvement of cyclic intermediates and has provided a rational basis for predicting the favoured reaction pathways. Novel camphor-derived phenyl sulfonate esters and N-adamantylsulfonamides have been synthesised for use as chiral auxiliaries in the Morita-Baylis-Hillman reaction. Modeling at the Molecular Mechanics level has provided useful insights into possible conformational constraints and an adamantyl sulfonate auxiliary has been successfully used in the stereoselective synthesis of a range of products, generally in excellent yield and with up to 95 % d.e.
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A critical ethnographic study of report writing as a literacy practice by automotive engineers
- Authors: Harran, Marcelle
- Date: 2007
- Subjects: English language -- Written English -- South Africa Written communication -- South Africa Literacy -- Social aspects -- South Africa Engineers -- Language -- South Africa Communication in engineering -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1476 , http://hdl.handle.net/10962/d1003357
- Description: This study describes the social practices involved in the situated activity of report writing in an engineering automotive discourse community in South Africa. In particular, the study focuses on the subjectivity of predominantly English Second Language (ESL) engineers writing reports by determining what literacy means to them and what meanings they give to dominant literacy practices in report writing, especially feedback in text production. In the South African engineering workplace, because of the diversity and complexity of language and identity issues, the appropriation of the required literacy skills tends to be multifaceted. This context is made more complex as English is the business language upon which engineering is based with engineering competence often related to English proficiency. Therefore, the study is located within the understanding that literacy is always situated within specific discoursal practices whose ideologies, beliefs, power relations, values and identities are manifested rhetorically. The basis for this critical theory of literacy is the assertion that literacy is a social practice which involves not only observable units of behaviour but values, attitudes, feelings and social relationships. As the institution’s socio-cultural context in the form of embedded historical and institutional forces impact on writer identity and writing practices or ways of doing report writing, notions of writing as a transparent and autonomous system are also challenged. As critical ethnography is concerned with multiple perspectives, it was selected as the preferred methodology and critical realism to derive definitions of truth and validity. Critical ethnography explores cultural orientations of local practice contexts and incorporates multiple understandings providing a holistic understanding of the complexity of writing practices. As human experience can only be known under particular descriptions, usually in terms of available discourses such as language, writing and rhetoric, the dominant practices emerging in response to the report acceptance event are explored, especially that of supervisor feedback practices as they causally impact on report-writing practices during the practice of report acceptance. Although critical realism does not necessarily demonstrate successful causal explanations, it does look for substantial relations within wider contexts to illuminate part-whole relationships. Therefore, an attempt is made to find representativeness or fit with situated engineering literacy practices and wider and changing literacy contexts, especially the impact of Higher Education and world Englishes as well as the expanding influence of technological and digital systems on report-writing practices.
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The development and transfer of core competencies in multinational corporations : a study of three South African originated multinational corporations, compared and contrasted with a leading United States multinational
- Authors: Harvey, Neil M
- Date: 2007
- Subjects: Management -- South Africa International business enterprises -- South Afrca International business enterprises -- United States Core competencies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1197 , http://hdl.handle.net/10962/d1008369
- Description: The thesis studies the development and transfer of core competencies in multinational corporations. It aims to advance the general body of knowledge relating to core competencies, to have practical applicability for management practitioners and academics, to explain how three companies from South Africa became global leaders in their fields and to examine the lessons they learned about international business. Three South African originated multinationals and a US multinational company were studied. The basic methodology is a case study. The methods of research were personal interviews, telephone interviews, written questionnaires, documents, archival records and direct observations. Value chains were used to evaluate the effectiveness of methods of development and transfer and the success of transfer of core competencies. It is concluded that different and multiple methods are needed to develop and transfer core competencies. The effectiveness of methods varies by company and value chain location. There is a significant high degree of correlation between the ratings of success in transferring core competencies and the effectiveness of the methods used to transfer them. This gives substantial credibility to the information provided by the companies and highlights the importance of selecting appropriate methods. There are some variances between the research results and established literature on the development and transfer of core competencies. There are notable differences between the companies from South Africa and the US multinational on the effectiveness of methods used to develop and transfer core competencies. There are also areas where all the companies are in accord. "Roadmaps" covering the effectiveness of methods for developing and transferring core competencies in different locations in a value chain are presented. Practical examples of the companies' actions relating to acquisitions and post-acquisition integration, their experiences in different countries, challenges they face, the methods used to assess transfer, avoid pitfalls and improve transfer, and other issues are also provided.The success of the multinationals from South Africa is explained by a combination of history, competitive factor conditions, management practices, attributes and leadership. The conclusions of the thesis are followed by recommendations on how to improve the management, development and transfer of core competencies.
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A sociological analysis of intermediary non-governmental organizations and land reform in contemporary Zimbabwe
- Authors: Helliker, Kirk David
- Date: 2007
- Subjects: Non-governmental organizations -- Zimbabwe Land reform -- Zimbabwe Land use -- Zimbabwe Sociology -- Philosophy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3303 , http://hdl.handle.net/10962/d1003091
- Description: The thesis offers an original sociological understanding of intermediary Non-Governmental Organizations (NGOs) in the modern world. This is pursued through a study of NGOs and land reform in contemporary Zimbabwe. The prevailing literature on NGOs is marked by a sociological behaviourism that analyses NGOs in terms of external relations and the object-subject dualism. This behaviourism has both ‘structuralist’ and ‘empiricist’ trends that lead to instrumentalist and functionalist forms of argumentation. The thesis details an alternative conceptual corpus that draws upon the epistemological and theoretical insights of Marx and Weber. The epistemological reasoning of Marx involves processes of deconstruction and reconstruction. This entails conceptualizing NGOs as social forms that embody contradictory relations and, for analytical purposes, the thesis privileges the contradiction between ‘the global’ and ‘the local’. In this regard, it speaks about processes of ‘glocalization’ and ‘glocal modernities’ in which NGOs become immersed. The social field of NGOs is marked by ambiguities and tensions, and NGOs seek to ‘negotiate’ and manoeuvre their way through this field by a variety of organizational practices. Understanding these practices necessitates studying NGOs ‘from within’ and drawing specifically on Weber’s notion of ‘meaning’. These practices often entail activities that stabilize and simplify the world and work of NGOs, and this involves NGOs in prioritizing their own organizational sustainability. In handling the tension between ‘the global’ and ‘the local’, NGOs also tend to privilege global trajectories over local initiatives. The thesis illustrates these points in relation to the work of intermediary NGOs in Zimbabwe over the past ten years. Since the year 2000, a radical restructuring of agrarian relations has occurred, and this has been based upon the massive redistribution of land. In this respect, local empowering initiatives have dramatically asserted themselves against globalizing trajectories. These changes have posed serious challenges to ‘land’ NGOs, that is, NGOs involved in land reform either as advocates for reform or as rural development NGOs. The thesis shows how a range of diverse ‘land’ NGOs has ‘handled’ the heightened contradictions in their social field in ways that maintain their organizational coherence and integrity.
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A taxonomic revision of the southern African endemic genus Gazania (Asteraceae) based on morphometric, genetic and phylogeographic data
- Authors: Howis, Seranne
- Date: 2007
- Subjects: Compositae Plant genetics DNA Endemic plants -- South Africa Plant ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4200 , http://hdl.handle.net/10962/d1003769
- Description: Gazania is a small genus of the subtribe Gorteriinae, tribe Arctoteae, that is endemic to southern Africa. The genus was last revised in 1959 by Roessler, who noted that delimitation of the species of Gazania can be “extraordinarily difficult”. Morphometric data was collected to test the reality of the 16 species as delimited by Roessler, who based species boundaries on morphological characters. Only six taxa were found to be morphologically distinct, while the remaining samples showed no species cohesion. DNA sequence data from two nuclear spacer regions (ITS and ETS) and four chloroplast noncoding regions (the trnL and rpS16 introns, and the psbA-trnH and trnL-F spacers) of 43 samples were utilised to create a species level phylogeny and to investigate correlations between genetically delimited units and morphologically defined taxa. DNA sequence data reveal that seven species (as delimited by Roessler) are morphologically and genetically distinct. The remaining nine of Roessler’s species fall into a morphologically and genetically overlapping continuum that forms an ochlospecies. Phylogeographic methods (based on an expanded ITS and ETS DNA sequence data set from 169 samples) were employed to further resolve the limits of species, with special focus on the clades within the ochlospecies. These genetically defined clades were correlated with their geographical distributions, and in combination with molecular dating techniques, used to elucidate the recent climatic or environmental factors that may have shaped the phylogeographic structure of the genus. Phylogeographic patterns and molecular dating reveals that the genus Gazania is an example of a South African endemic clade that has undergone episodic cladogenesis in response to fluctuating climatic conditions over the last seven million years. The ochlospecies within Gazania is a result of repeated cycles of climate driven isolation in refugia and subsequent expansion and hybridization events during the Pliocene and Pleistocene. Comparisons with phylogeographic studies on other organisms reveal a common pattern indicative of the presence and evolutionary importance of an ancestral refugium in the arid Richtersveld / Namib region of southern Africa.
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Field and laboratory analyses of manual tasks in the South African automotive industry
- Authors: James, Jonathan Peter
- Date: 2007
- Subjects: Automobile industry and trade -- South Africa -- Safety measures , Human engineering -- South Africa , Automobile industry workers -- South Africa -- Health risk assessment , Industrial safety -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5121 , http://hdl.handle.net/10962/d1005199 , Automobile industry and trade -- South Africa -- Safety measures , Human engineering -- South Africa , Automobile industry workers -- South Africa -- Health risk assessment , Industrial safety -- South Africa
- Description: The present study adopted a “field-laboratory-field” approach in the assessment of the efficacy of ergonomics interventions specific to two selected tasks evaluated in a South African automotive industry. Initial field testing was conducted in an Eastern Cape (South Africa) automotive plant where high risk areas were identified during walkthrough ergonomics surveys in conjunction with interaction with operators. Temporal factors and working postures of 12 industrial workers were recorded and observed, while physiological and perceptual responses were assessed. Two priority areas were focused upon for analysis, namely the Paintshop and Bodyshop with the former identified as being the more taxing of the two tasks. Responses of 30 students participating in rigourously controlled laboratory simulations were subsequently collected while completing the two tasks, namely the Paintshop Trolley Transfer (PTT) and Car Door Carriage (CDC) for participants. Working postures, kinematic, physiological and perceptual responses were assessed pre- and post-intervention. Following the laboratory experimentation a basic re-evaluation was conducted at the plant to assess whether the proposed changes had a positive effect on working postures, physiological and perceptual responses. The results of the preliminary field investigation revealed a prevalence of awkward working postures and excessive manual work in both areas. Laboratory experimentation revealed a notable reduction in task demands pre- versus post-intervention. The PTT mean lean angle for two-handed pre-intervention pulling observations of 23.7° (±3.51) was reduced to 13.9° (±2.21) post-intervention. Low back disorder (LBD) risk was reduced during the two-handed pull intervention (from 36.8% ±8.03 to 21.7% ±5.31). A significant decrement in heart rate responses from 103 bt.min-1 (±11.62) to 93 bt.min[superscript -1] (±11.77) was recorded during the two-handed symmetrical pushing intervention. The electromyography (EMG) responses for one-handed pushing and pulling pre-intervention showed the highest levels of muscular activity in the right medial deltoid due to an awkward and asymmetrical posture. CDC responses demonstrated that minor changes in the storage height of the door resulted in a significant reduction in sagittal flexion from 28.0° (±4.78) to 20.7° (±5.65). Predictions of average probability of LBD risk were significantly reduced from 50.3% (±5.91) to 39.8% (±5.10) for post-intervention car door lifting. In addition, the greatest reduction in EMG activity as a %MVC was achieved during sub-task ii (reduced from 35.1 to 13.7% and 30.5 to 13.9% for left and right erector spinae respectively) which was associated with the introduction of the transfer trolley for the door transfer phase of the CDC. Re-evaluation in the automotive plant revealed that the most notable change has been the implementation of automated ride on trolleys in the Paintshop. The Bodyshop area has also been modified to allow more effective job rotation and the step into the storage bin has been reduced via a “low-cost” stepping platform. Mean heart rate recordings were reduced from 94 (±9.77) bt.min[superscript -1] to 81 (±3.72) bt.min[superscript -1] in the Paintshop. Overall the results demonstrate the effect of “low-cost” interventions in reducing the physical stresses placed on workers in the automotive industry where much of the work is still done manually.
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Trends in fish community structure and recruitment in a temporarily open/closed South African estuary
- Authors: James, Nicola Caroline
- Date: 2007
- Subjects: Fish communities -- South Africa -- Eastern Cape Marine fishes -- South Africa -- Eastern Cape Estuarine fishes -- South Africa -- Eastern Cape Estuarine ecology -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5332 , http://hdl.handle.net/10962/d1005178
- Description: Long-term interannual changes in richness, abundance, diversity and structure of the fish community in the temporarily open/closed East Kleinemonde Estuary, Eastern Cape, are described and the recruitment success of two estuary-dependent marine species assessed. In addition, laboratory experiments were conducted to assess the possible role of olfaction in the recruitment process of an estuary-dependent marine fish species. Multivariate analyses of the annual marine fish communites identified two distinct groups with more species recorded during years that succeeded spring (September to November) mouth opening events than in years following no mouth opening events in spring. Interannual community stability (IMD) and seriation (IMS) also increased from the ‘other’ to the ‘spring’ years. These results highlight the importance of the timing of mouth opening to the marine fish community in a temporarily open/closed estuary. This study also made use of long-term records of daily mouth state and linked them to the recruitment of distinct year-class cohorts in two spardis with contrasting lifehistory characteristics. Lithognathus lithognathus only recruited into the estuary in years when the mouth opened between late August and January. This was linked to the limited spawning season of this species and its inability to enter closed estuaries via wave overwash events. In contrast, recruitment by Rhabdosargus holubi juveniles appeared to be uninterrupted and was not determined by the seasonality of mouth opening. This species dominates the marine-spawning component of the East Kleinemonde Estuary and its success is attributed to an extended spawning season and its ability to recruit into estuaries during both overwash and open mouth conditions. Attraction of postflexion Rhabdosargus holubi larvae to estuary, surf zone and river water was also measured using a rectangular choice chamber. In two sets of experiments, conducted during peak recruitment periods, larvae from both the surf zone and estuary mouth region selected estuary water with a significantly higher frequency than sea water. Larvae collected in the mouth region showed a stronger preference for river water than those collected in the surf zone, thus suggesting that these fish are more attracted to freshwater influenced nursery areas once they have entered the estuary than those in the surf zone. Larvae collected in the marine environment also selected surf zone water with significantly higher frequencies than estuary water or offshore sea water, thus confirming the importance of the surf zone as an interim nursery area for postflexion R. holubi.
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Regulation of hyu gene expression in Agrobacterium tumefaciens strains RU-AE01 and RU-OR
- Authors: Jiwaji, Meesbah
- Date: 2007
- Subjects: Agrobacterium tumefaciens Amino acids Gene expression Hydrolysis Hydantoin Enzymes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3983 , http://hdl.handle.net/10962/d1004042
- Description: Several Agrobacterium tumefaciens strains have been isolated for their ability to produce D-amino acids from D, L-substituted hydantoins. The optically pure D-amino acids are used in the synthesis of pharmaceuticals, as food additives and as insecticides. This hydrolysis of D, L-substituted hydantoins is catalysed by two hydantoin-hydrolyzing enzymes, an hydantoinase and an N-carbamyl amino acid amidohydrolase. While the hydantoin-hydrolyzing enzymes have been studied in detail, the mechanisms that control expression of the hyu genes have not. The research reported in this work elucidates some of the mechanisms involved in the regulation of the hyu genes in A. tumefaciens strains. The hydantoin-hydrolyzing enzyme activity from the environmental isolate A. tumefaciens RU-AE01 was characterized. A broad host range vector for the simultaneous analysis of divergent promoters was constructed. The promoter regions responsible for the activation of transcription of hyuH and hyuC were identified by deletion analysis. It was proposed that transcription of hyuH was activated by a putative σ[superscript 54]-dependent promoter or a putative σ[superscript 70]-dependent promoter identified upstream of the hyuH gene. The hyuC gene was activated by a putative σ[superscript 70]-dependent promoter identified upstream of the hyuC gene. The regulation of hydantoinase and N-carbamyl amino acid amidohydrolase enzyme activity was compared to the regulation of transcription from the RU-AE01 hyuH-hyuC region. Expression of the hydantoin-hydrolyzing enzymes was regulated by induction which correlated with reporter enzyme expression from the hyuH and hyuC promoter regions. However, the expression of the hydantoin-hydrolyzing enzymes was also regulated by nitrogen catabolite repression (NCR). This did not correlate to the reporter gene expression of the hyuH promoter region but did compare to the reporter gene expression of the hyuC promoter region. This suggested that NCR of hyuH was at the post-translational level whereas NCR of the hyuC promoter was at the transcriptional level. Pathways involved in the regulation of the hyu genes were characterized. The production of the hydantoin-hydrolyzing enzymes in both A. tumefaciens strains RU-AE01 and RU-OR were regulated by proteins involved in the global ntr pathway. The levels of the hydantoin-hydrolyzing enzymes in strain RU-AE01 were elevated in the presence of increased levels of NtrB and NtrC illustrating the importance of the ntr pathway in the regulation of the levels of the hydantoin-hydrolyzing enzymes. Similarly, in RU-OR the presence of exogenous NtrB and NtrC elevated levels of N-carbamyl amino acid amidohydrolase activity. However, the levels of hydantoinase enzyme activity in strain RU-OR were elevated in the presence of NtrC alone. In addition, the presence of a His6-tagged NtrC molecule abolished the elevation in the levels of the hydantoinase but not the N-carbamyl amino acid amidohydrolase enzyme activity in strain RU-OR. This suggests that NtrC has a direct role in the regulation of the expression of hyuH in RU-OR. In addition, it indicates that the hyu genes in the two A. tumefaciens strains RU-AE01 and RU-OR are different. The presence of the RU-AE01 hyuH-hyuC fragment caused a dramatic increase in the hydantoin-hydrolyzing enzyme activity in strain RU-OR but not strain RU-AE01. This implied the incidence of a possible repressor protein in RU-OR, which is titrated out by the presence of the RU-AE01 hyuH-hyuC fragment. Protein-DNA binding assays suggest that this putative repressor may be 38 kDa in RU-OR cells.
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Genesis of environmental education policy in Botswana: construction and interpretation
- Authors: Ketlhoilwe, Mphemelang Joseph
- Date: 2007
- Subjects: Environmental education -- Botswana Education and state -- Botswana
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1549 , http://hdl.handle.net/10962/d1003431
- Description: This study is based on the 1994 Revised National Policy on Education (Botswana Government, 1994) that introduced environmental education into the Botswana’s education system. The main goals of this study were to understand the genealogy of and to critically analyze governmentality associated with environmental education policy in Botswana. Drawing on a post-structural genealogical approach to the subject matter (following Foucault) global historical events and their influence on policy in Botswana, views on environmental education and interpretation, and power relations in environmental education policy discourses were investigated. An investigation was conducted through document analysis, interviews, focus group discussions and observations. The analysis revealed that power relations have historically transcended environmental education policy discourses from global, regional to national levels. The exercise of power through international bodies, and bilateral and multilateral agreements has impacted on Botswana enabling her to enact policies to address socio-ecological crises or regulating them to sustainably utilize natural resources. However, evidence has shown that although Botswana accepted and introduced environmental education, structures were not ready for its implementation and hence some contextual problems are experienced by teachers in schools. The Revised National Policy on Education (RNPE) was constructed through a consultative process, but the final decision on what goes into the policy text was decided from the top (i.e. by the Ministry of Education senior officials). It emerged from this study that Botswana has inconsistently adopted sustainability and conservation-protection discourses in environmental education policy. The mix of the two discourses shows continuity of the protectionist-conservationist discourses and emergence of the current sustainable use discourse, creating a complex discourse environment. The study also revealed that in including these primarily western scientific discourses, other discourses were marginalized or excluded, which revealed continuity with colonial education discourses. The findings also revealed variance in the understanding of environmental education. The majority of the teachers understood and normalised new knowledge in environmental education as Environmental Science or Science, and equated environmental management activities with environmental education. Teachers deployed new governmentalities and normalizing strategies by following the traditional conservation and science epistemological and pedagogical discourses. They exercised various self-governing strategies to respond to the RNPE requirement regarding environmental education. The findings highlight the need for re-conceptualization of environmental education at macro(at Ministry of Education) and micro level. There is a need to harmonize the variation in policy interpretations and clarification of the conservation/environmental education and sustainability discourses running parallel in schools or to work more explicitly with multiple discourses. It has also emerged that teacher support mechanisms need review to enhance policy implementation. The study recommends that further and explicit analysis of environmental education discourses is critical for shaping the future of environmental education policy development and interpretation within Botswana’s education system.
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Causes of persistent rural poverty in Thika district of Kenya, c.1953-2000
- Authors: Kinyanjui, Felistus Kinuna
- Date: 2007
- Subjects: Poverty -- Kenya -- History Rural poor -- Kenya -- History Agriculture -- Kenya -- History Kenya -- History Kenya -- Politics and government
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2547 , http://hdl.handle.net/10962/d1002399
- Description: This study investigates the causes of poverty among the residents of Thika District in Kenya over the period 1953-2000. Using the articulation of modes of production perspective, the study traces the dynamics of poverty to the geography, history and politics of Thika District. The thrust of the argument is that livelihoods in the district changed during the period under investigation, but not necessarily for the better. Landlessness, collapse of the coffee industry, intergenerational poverty, and the ravages of diseases (particularly of HIV/AIDS) are analysed. This leads to the conclusion that causes of poverty in Thika District during the period under examination were complex as one form of deprivation led to another. The study established that poverty in Thika District during the period under review was a product of a process of exclusion from the centre of political power and appropriation. While race was the basis for allocation of public resources in colonial Kenya, ethnicity has dominated the independence period. Consequently, one would have expected the residents of Thika District, the home of Kenya’s first president, Mzee Jomo Kenyatta, to have benefited inordinately from public resources during his rule. Kenyatta’s administration, however, mainly benefited the Kikuyu elite. The study therefore demonstrates that during the period under examination, the Kikuyu, like any other Kenyan community, were a heterogeneous group whose differences were accentuated by class relations. Subaltern groups in Thika District therefore benefited minimally from state patronage, just like similar groups elsewhere in rural Kenya. By the late 1970s, the level of deprivation in rural Kenya had been contained as a result of favourable prices for the country’s agricultural exports. But in the subsequent period, poverty increased under the pressures of world economic recession and slowdowns in trade. The situation was worse for Kikuyu peasants as the Second Republic of President Daniel Moi deliberately attempted undermine the Kikuyu economically. For the majority of Thika residents, this translated into further marginalisation as the Moi regime lumped them together with the Kikuyu elite who had benefitted inordinately from public resources during the Kenyatta era. This study demonstrates that no single factor can explain the prevalence of poverty in Thika District during the period under consideration. However, the poor in the district devised survival mechanisms that could be replicated elsewhere. Indeed, the dynamics of poverty in Thika District represent a microcosm not just for the broader Kenyan situation but also of rural livelihoods elsewhere in the world. The study recommends land reform and horticulture as possible ways of reducing poverty among rural communities. Further, for a successful global war on poverty there is an urgent need to have the West go beyond rhetoric and deliver on its promises to make poverty history.
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The role of ants in structuring insect communities on the canopies of senegalia drepanolobium near Laikipia, Kenya
- Authors: Kuria, Simon Kamande
- Date: 2007
- Subjects: Ants -- Kenya Ants -- Behavior Insect societies -- Kenya Forest canopy ecology -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5758 , http://hdl.handle.net/10962/d1005446
- Description: In the black cotton ecosystem of Laikipia, Kenya, four symbiotic ants coexist at a fine spatial scale on canopies of Senegalia drepanolobium. They exhibit different aggressive behaviours and modify their tree canopies differently. These diverse behaviours were expected to affect the associated canopy arthropod communities. At the Kenya long-term exclosure experiment (KLEE) and its immediate environs at Mpala Research Centre, Laikipia, the insect communities coexisting with each of the four ant species were characterized, and their response to different vertebrate herbivory. Other ant species inhabiting the tree canopies or the ground were surveyed too. Pitfall trapping was used in sampling terrestrial ants, while beating and mist-blowing were used in collecting arboreal insects. Different sampling methods had varying efficacies, revealing the importance of using several methods. There are at least sixteen ant species in this ecosystem, all occurring on the ground, but only ten species on the trees. Terrestrial ant communities in this ecosystem cannot be used as indicators of grazing pressure for range management. A total of 10,145 individual insects were collected from the tree canopies, comprising of 117 species from seven orders and 25 families, forming a complex community of species interacting at different levels. Symbiotic ant species had a significant effect on insect community structure and composition. Crematogaster sjostedti was associated with a community that was significantly different from the other ant species. There was no significant effect of vertebrate feeding pressure on the canopy insect community, but there was an interaction effect between ant species and treatments. Significant differences between ant species mostly occurred on treatment plots where only cows were allowed to graze. One or more of the ant species may be a keystone species in this ecosystem even though experimental manipulations failed to confirm earlier findings. It was concluded that the one-year period during which experimental manipulations were carried out was not long enough to reflect takeover effects on the insect community. The four symbiotic ant species colonizing S. drepanolobium comprises of two guilds, the hemipteran-tending ants (C. sjostedti and Crematogaster mimosae) and non-tending ants (Crematogaster nigriceps and Tetraponera penzigi). Communities associated with these guilds were found to be significantly different in all four diversity indices. The black cotton ecosystem is species-poor compared to other ecosystem such as forests. The number of insect species that colonizes S. drepanolobium and coexists with acacia-ants forms a large proportion of the invertebrate community. Therefore, this ecosystem should be conserved to safeguard this invertebrate community. This will also give scientists a chance to establish how the various insect species coexist with symbiotic ants on tree canopies.
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