Characterization of the Hsp40 partner proteins of Plasmodium falciparum Hsp70
- Authors: Njunge, James Mwangi
- Date: 2014
- Subjects: Plasmodium falciparum , Heat shock proteins , Malaria -- Chemotherapy , Protein-protein interactions , Erythrocytes -- Biotechnology , Molecular chaperones , Host-parasite relationships , Mitochondria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4117 , http://hdl.handle.net/10962/d1013186
- Description: Human malaria is an economically important disease caused by single-celled parasites of the Plasmodium genus whose biology displays great evolutionary adaptation to both its mammalian host and transmitting vectors. This thesis details the 70 kDa heat shock protein (Hsp70) and J protein chaperone complements in malaria parasites affecting humans, primates and rodents. Heat shock proteins comprise a family of evolutionary conserved and structurally related proteins that play a crucial role in maintaining the structural integrity of proteins during normal and stress conditions. They are considered future therapeutic targets in various cellular systems including Plasmodium falciparum. J proteins (Hsp40) canonically partner with Hsp70s during protein synthesis and folding, trafficking or targeting of proteins for degradation. However, in P. falciparum, these classes of proteins have also been implicated in aiding the active transport of parasite proteins to the erythrocyte cytosol following erythrocyte entry by the parasite. This host-parasite “cross-talk” results in tremendous modifications of the infected erythrocyte, imparting properties that allow it to adhere to the endothelium, preventing splenic clearance. The genome of P. falciparum encodes six Hsp70 homologues and a large number of J proteins that localize to the various intracellular compartments or are exported to the infected erythrocyte cytosol. Understanding the Hsp70-J protein interactions and/or partnerships is an essential step for drug target validation and illumination of parasite biology. A review of these chaperone complements across the Plasmodium species shows that P. falciparum possesses an expanded Hsp70-J protein complement compared to the rodent and primate infecting species. It further highlights how unique the P. falciparum chaperone complement is compared to the other Plasmodium species included in the analysis. In silico analysis showed that the genome of P. falciparum encodes approximately 49 J proteins, 19 of which contain a PEXEL motif that has been implicated in routing proteins to the infected erythrocyte. Most of these PEXEL containing J proteins are unique with no homologues in the human system and are considered as attractive drug targets. Very few of the predicted J proteins in P. falciparum have been experimentally characterized. To this end, cell biological and biochemical approaches were employed to characterize PFB0595w and PFD0462w (Pfj1) J proteins. The uniqueness of Pfj1 and the controversy in literature regarding its localization formed the basis for the experimental work. This is the first study showing that Pfj1 localizes to the mitochondrion in the intraerythrocytic stage of development of P. falciparum and has further proposed PfHsp70-3 as a potential Hsp70 partner. Indeed, attempts to heterologously express and purify Pfj1 for its characterization are described. It is also the first study that details the successful expression and purification of PfHsp70-3. Further, research findings have described for the first time the expression and localization of PFB0595w in the intraerythrocytic stages of P. falciparum development. Based on the cytosolic localization of both PFB0595w and PfHsp70-1, a chaperone – cochaperone partnership was proposed that formed the basis for the in vitro experiments. PFB0595w was shown for the first time to stimulate the ATPase activity of PfHsp70-1 pointing to a functional interaction. Preliminary surface plasmon spectroscopy analysis has revealed a potential interaction between PFB0595w and PfHsp70-1 but highlights the need for further related experiments to support the findings. Gel filtration analysis showed that PFB0595w exists as a dimer thereby confirming in silico predictions. Based on these observations, we conclude that PFB0595w may regulate the chaperone activity of PfHsp70-1 in the cytosol while Pfj1 may play a co-chaperoning role for PfHsp70-3 in the mitochondrion. Overall, this data is expected to increase the knowledge of the Hsp70-J protein partnerships in the erythrocytic stage of P. falciparum development, thereby enhancing the understanding of parasite biology.
- Full Text:
Combating corruption while respecting human rights : a critical study of the non-conviction based assets recovery mechanism in Kenya and South Africa
- Authors: Obura, Ken Otieno
- Date: 2014
- Subjects: Human rights -- Kenya , Human rights -- South Africa , Corruption -- Kenya , Corruption -- South Africa , Reparation (Criminal justice) -- Kenya , Reparation (Criminal justice) -- South Africa , Political corruption -- Kenya , Political corruption -- South Africa , Corruption investigation -- Kenya , Corruption investigation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3719 , http://hdl.handle.net/10962/d1013159
- Description: The thesis contributes to the search for sound anti-corruption laws and practices that are effective and fair. It argues for the respect for human rights in the crafting and implementation of anti-corruption laws as a requisite for successful control of corruption. The basis for this argument is threefold: First, human rights provide a framework for checking against abuse of state’s police power, an abuse which if allowed to take root, would make the fight against corruption lose its legitimacy in the eye of the people. Second, human rights ensure that the interest of individuals is catered for in the crafting of anti-corruption laws and practices thereby denying perpetrators of corruption legal excuses that can be exploited to delay or frustrate corruption cases in the courts of law. Third, human rights provide a useful framework for balancing competing interests in the area of corruption control – it enables society to craft measures that fulfils the public interest in the eradication of corruption while concomitantly assuring the competing public interest in the protection of individual members’ liberties – a condition that is necessary if the support of the holders of these competing interests is to be enlisted and fostered in the fight against corruption. The thesis focuses on the study of the non-conviction based assets recovery mechanism, a mechanism that allows the state to apply a procedure lacking in criminal law safeguards to address criminal behaviour. The mechanism is thus beset with avenues for abuse, which if unchecked could have debilitating effects not only to individual liberties but also to the long term legitimacy of the fight against corruption. In this regard, the thesis examines how the human rights framework has been used in Kenya and South Africa to check on the potential dangers of the non-conviction based mechanism and to provide for a proportional balance between the imperative of corruption control and the guarantee against arbitrary deprivation of property. The aim is to unravel the benefits of respecting human rights in the fight against corruption in general and in the non-conviction based assets recovery in particular. Kenya and South Africa are chosen for study because they provide two models of non-conviction based mechanisms with different levels of safeguards, for comparative consideration.
- Full Text:
Control, compliance and conformity at the University of Fort Hare 1916 - 2000: a Gramscian approach
- Authors: Johnson, Pamela
- Date: 2014
- Subjects: University of Fort Hare -- History , University of Fort Hare -- Administration , Higher education and state -- South Africa , Hegemony -- South Africa , Conformity -- Political aspects -- South Africa , Abuse of administrative power -- South Africa , Education, Higher -- South Africa -- Eastern Cape , South Africa -- Politics and government -- 1916-2000 , Apartheid -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1325 , http://hdl.handle.net/10962/d1013126
- Description: Arising from Marxist theory, critical theory investigates the mechanisms that enable continued domination in capitalist society, with a view to revealing the real, but obscured, nature of social relations and enabling these to be challenged by subjugated classes. Within the broad spectrum of Marxist theory, social relations of domination and subordination are assigned according to the relationship of social classes to economic production. However, the neo-Marxist perspective developed by Antonio Gramsci locates relations of power within the broader context of the political economy. In doing so, the role of the State in a capitalist society assumes greater significance than that of maintaining and securing social relations on behalf of the dominant class through coercion and force. Instead, the State embarks on a range of activities in the attempted “exercise of hegemony”, or the cultivation of general acceptance by all social classes of existing social relations and conditions. Gramsci refers to this desired outcome as “consent”, the product of the successful exercise of hegemony, a political function which is thus crucial to the accumulation of capital. When unsuccessful, dissent cannot be contained by the State, and the extent to which contestation constitutes a threat is revealed by recourse to coercion. The manner in which relations of power are cemented through the exercise of hegemony lies at the core of this thesis. It investigates the relationship between the State and the administrators of an institution within civil society, the University of Fort Hare, as well as the responses to the activities of the State and University Administration within the University itself, over an extended period of time between 1916 and 2000. This period is divided into three specific time frames, according to changes in the expression of the South African State. In general, it is seen that conformity characterises the relationship between the State and the University Administration, underscoring the success of the State in fostering the role of education in the reproduction of social relations and values and in eliciting conformity. The nature of conformity is seen to vary according to different expressions of the State and changes in social relations, which are in turn informed by the overarching political economy and events taking place within society and the University of Fort Hare. Manifestations of consent and dissent, as responses to the attempted exercise of hegemony, are presented in the three periods corresponding to different expressions of the State. Four reasons for conformity, as presented by Gramscian scholar Joseph V Femia (1981), are utilised in order to explain and illustrate the nature of control and compliance at the University of Fort Hare between 1916 and 2000.
- Full Text:
Cultural bias on the IELTS examination
- Authors: Freimuth, Hilda
- Date: 2014
- Subjects: International English Language Testing System -- Evaluation Language and culture -- United Arab Emirates English language -- Study and teaching -- Foreign speakers English language -- Examinations Critical realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1324 , http://hdl.handle.net/10962/d1012088
- Description: The study reported in this thesis investigated Emirati students’ claims related to experiences of cultural bias of the reading component of the IELTS examination through a critical realist lens. Critical realism posits a layered reality which allows for the conceptualization of experiences as emerging from the interplay of events and mechanisms found in two other realms of reality – the actual and the real. Experiences, therefore, have a different ontological status than the events and the causal mechanisms to which they are attributed. Social realism was used to further explore the depth of the realm of the real through Archer’s construct of analytical dualism. This allowed for the placement of generative mechanisms into three domains: structure, culture, and agency. There were two parts to this investigation: a content analysis and a focus group study. The first part of the content analysis consisted of analyzing 60 reading passages from 20 IELTS examinations for a number of cultural categories. These included such things as cultural objects, social roles, idiomatic expressions, traditions and festivals, superstitions and beliefs, and political and historical settings. The second part of the content analysis focused on the question types and syntactical structure of the 5 different IELTS examinations that the focus groups students sat. All three components of the analysis – the cultural content, question types, and syntactical structure – were conducted at the level of the actual. Findings indicated that on average, an IELTS examination contained 14 cultural references of various kinds. Only 4% of all geographical references pertained to the Middle East with the biggest share being western locations. The most common question types were matching questions, fill in the blank questions, and yes/no questions with more than 50% of all questions requiring some form of higher order thinking due to text reinterpretation. The study also found that the question types were not consistently distributed over the examinations with each consisting of a different variety of questions and some even having repetitive question types on one reading examination. The second part of the study was the focus groups. Here, 21 Emirati students sat 5 different IELTS examinations. Upon test completion, these students underwent a semistructured interview to relate their experiences of the test. These experiences, at the level of the empirical, all shared 7 ideas: reading is hard, the questions are too difficult, the passages are too long and difficult, the topics are unfamiliar, the topics are not interesting, the vocabulary is too difficult, and there is not enough time. When the processes of retroduction and abduction were applied to both the content analysis and these common experiences, numerous structures and discourses at the level of the real were identified as having contributed to the emergence of the feeling of bias at the level of the empirical. These structures included such things as the students’ school system (eg. curriculum, assessment, instructors etc.), religion, literacy practices, and home. In the cultural domain, a number of discourses were found to contribute to the experiences at the level of the empirical. Amongst these were the ‘Unimportance of Reading’, the culture of ‘Obedience’, the rejection of the ‘un-Islamic’, and the students’ sense of ‘Entitlement’.
- Full Text:
Curriculum outcomes, teaching practices and learner competencies in isiXhosa in three Grahamstown schools
- Authors: Fobe, Mila Pamella
- Date: 2014
- Subjects: Xhosa language -- Study and teaching (Primary) -- South Africa -- Grahamstown Xhosa language -- Study and teaching (Secondary) -- South Africa -- Grahamstown Language and education -- South Africa -- Grahamstown Curriculum planning Second language acquisition Public schools -- South Africa -- Grahamstown Language policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3630 , http://hdl.handle.net/10962/d1012072
- Description: This study looks at the curriculum outcomes, teaching practices and learner competencies in isiXhosa at three Eastern Cape schools and across three different grades, 7-9. It explores the link between language learning and teaching as well as the teaching strategies used within the classroom. In particular, the study seeks to analyse how isiXhosa is taught at three different levels of instruction, namely at Home Language (HL), First Additional Language (FAL) and Second Additional Language (SAL) levels. Qualitative methods were used, and the study took the form of interpretive case studies within the respective schools. The purpose of using multiple case studies was to investigate the reality within the three sites selected. The three schools had three extreme settings, in the sense that one of the schools is a rich isiXhosa environment and the other two schools are English environments. The tools used for data gathering were interviews, classroom observations, and an analysis of documents from the Department of Basic Education. Data was then presented and analysed in Chapter 4 and 5 against the backdrop of an extensive literature review in Chapter 2 as well as a detailed methodological approach as outlined in Chapter 3. One of the findings of this research indicates that in two of the schools the teaching culture is largely from a western perspective, whereas in one of the schools the learners are primarily isiXhosa speaking and teachers use a different linguistic approach to imparting knowledge. In the private and ex-Model C school it was found that a lack of exposure to isiXhosa is the primary cause of language problems for L2 learners. Secondly the L1 is not appropriately maintained or promoted in the school environment because it is presumed that learners are sufficiently exposed to their L1 at home. The research found therefore that in this particular schooling environment there is an inconsistency between the curricula that is taught in relation to the linguistic abilities of the learners, many of whom are mother tongue speakers of isiXhosa. Furthermore and more generally, it was found that teachers are still not well informed concerning South Africa’s Language-in-Education-Policy and there is a need for more inservice training that will focus on the nature of additional language acquisition in order to address the challenges of teaching these languages. The thesis concludes that extensive work needs to be done in order to reposition the teaching of isiXhosa at all three levels, but particularly at FAL level. This research shows that there is a disjuncture between the proposed curriculum/learning outcomes and the standards or levels achieved by the learners, more especially at FAL and SAL where oral proficiency in isiXhosa remains a challenge. Specific recommendations are contained in the final chapter of the thesis which also makes reference to the draft policy of the Ministry of Basic Education regarding the incremental introduction of the teaching of African languages from 2014 onwards. This thesis also makes takes as a point of departure the importance of multilingualism in a multicultural society such as South Africa where language is suggested as a strong factor in the fostering of social cohesion. It is for this reason that the thesis argues that the expert teaching of African languages, in this case isiXhosa, at both mother tongue and second language levels is of fundamental importance to the future of South African society.
- Full Text:
Development of an ionospheric map for Africa
- Authors: Ssessanga, Nicholas
- Date: 2014
- Subjects: Ionosondes Ionosphere Ionosphere -- Observations Ionosphere -- Research -- Africa Ionospheric electron density -- Africa Ionospheric critical frequencies
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5519 , http://hdl.handle.net/10962/d1011498
- Description: This thesis presents research pertaining to the development of an African Ionospheric Map (AIM). An ionospheric map is a computer program that is able to display spatial and temporal representations of ionospheric parameters such as, electron density and critical plasma frequencies, for every geographical location on the map. The purpose of this development was to make the most optimum use of all available data sources, namely ionosondes, satellites and models, and to implement error minimisation techniques in order to obtain the best result at any given location on the African continent. The focus was placed on the accurate estimation of three upper atmosphere parameters which are important for radio communications: critical frequency of the F2 layer (foF2), Total Electron Content (TEC) and the maximum usable frequency over a distance of 3000 km (M3000F2). The results show that AIM provided a more accurate estimation of the three parameters than the internationally recognised and recommended ionosphere model (IRI-2012) when used on its own. Therefore, the AIM is a more accurate solution than single independent data sources for applications requiring ionospheric mapping over the African continent.
- Full Text:
Development of styrene based imprinted sorbents for selective clean-up of metalloporphyrins in organic media
- Authors: Awokoya, Kehinde Nurudeen
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54521 , vital:26580
- Description: Most crude oils contain traces of vanadium and nickel complex with porphyrins (VTPP and NTPP) within their asphaltene fraction. Although these metals are only present in trace quantities, they have a significant and detrimental impact on the refining process by degrading the quality of intermediate and end products. Therefore, their selective removal is highly desirable. This thesis presents the development of nickel porphyrin, nickel vanadyl porphyrin imprinted nanofibers and vanadyl porphyrin imprinted polymer (MIP) particles for application as selective sorbents. Computational model based on the combination of molecular dynamics simulations and quantum mechanics was successfully applied to the styrene functional monomer selection. The particle was prepared by bulk polymerization and the nanofibers by a novel approach combining molecular imprinting and electrospinning technology. The morphologies, thermal stabilities and porosities of the imprinted sorbents were studied using SEM, TGA, and BET nitrogen gas adsorption. Chloroform was found to swell the polymer particles to a higher degree than methanol and acetonitrile. The adsorption characteristics of the imprinted sorbents best fitted with Freundlich isotherm model. The imprinted sorbents recorded high extraction efficiencies (EEs) of > 99 % in selectively extracting the metalloporphyrins. The impact of the template on the affinity of recognition for NTPP was evaluated. The results showed that the NTPP adsorption capacity increased as the molar ratio of NTPP to styrene was increased from 1:1 to 3:1. The optimal ratio of template to functional monomer which yielded the best specific affinity and highest recovery (99.9 %) was 3:1. The effects of trifluoroacetic acid (TFA), dichloromethane (DCM), dimethyl sulphoxide (DMSO), pentane (PEN) on electro-spinnability of the polymer solutions and the morphological appearance of the nanofibers were investigated. The imprinted nanofibers exhibited the same selectivity specialism for both NTPP and VTPP. A remarkable stability in relation to reusability was observed when imprinted nanofibers were used, as they could be reused nine times without incurring any significant loss in removal efficiency. The results were validated by analysing a certified reference material. The imprinted sorbents were therefore found to be selective sorbents that are well suited for handling trace metals in organic media.
- Full Text:
Direct and indirect effects of zooplanktivorous predators on the estuarine plankton community
- Authors: Wasserman, Ryan John
- Date: 2014
- Subjects: Zooplankton -- Effect of predation on , Predation (Biology) , Zooplankton -- Predators of , Copepoda
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5870 , http://hdl.handle.net/10962/d1012938
- Description: Although predation has been identified as a potentially important driver in terrestrial and freshwater ecosystems, estuarine planktonic research has focused largely on the so-called "bottom-up" drivers of community assemblages. As such, this thesis focuses on the direct and indirect effects of zooplanktivorous predators on the planktonic community in an estuarine environment. By using a suite of in situ mesocosm experiments, a number of hypotheses, pertaining to the major research themes associated with predator-prey interactions, are tested. These themes included trophic cascading, risk effects associated with predation events and the importance of predator diversity in maintaining prey communities. The first experiment assessed the significance of apex predation pressure for the planktonic community through trophic cascades. Various treatments using in situ mesocosms were established in a closed oligotrophic estuary to highlight the importance of predation in stabilising estuarine plankton abundances. Through either the removal (filtration) or addition of certain planktonic groups, varied trophic scenarios were established. The experimental treatment containing apex zooplanktivores had consequences for multiple trophic levels, exerting a stabilising pressure throughout the food web (Chapter 3). Furthermore, pyrosequencing of filtered water samples revealed that when compared to the remaining treatments, the treatment containing stable apex predatory pressure experienced limited temporal deviation-from-initial in bacterial community structure (Chapter 4). These findings are consistent with trophic cascade theory whereby predators mediate interactions at multiple lower trophic levels with consequent repercussions for diversity. To assess the non-consumptive effects of predators on prey, two experiments were conducted. Firstly, using egg numbers per clutch as a measure of potential reproductive output, the non-lethal effects of predatory pressure on reproductive success in a key planktonic copepod was investigated. In this study, the average clutch size of fecund female copepods was found to be consistently lower in the presence of predators when compared to females not exposed to predation threat (Chapter 5). The second study assessed the effects of conspecific chemical alarm cues associated with predation, on population dynamics of a copepod species. This study revealed that the copepods appear to detect the presence of chemical alarm cues associated with predation events, with repercussions for population demographics over time. Furthermore, it showed that in the absence of actual predation, copepod prey responses to alarm cues were adjusted over time, consistent with the threat sensitive predator avoidance hypothesis (Chapter 6). The final data chapter dealt with predator diversity and its implications for zooplankton community structure. By experimentally monitoring the effects of two alternate model predators on the metazoan community over time, dissimilarities in community level control emerged. Alternate key prey populations were regulated by the different model predators, highlighting the importance of predator and prey behaviour in mediating predator-prey interactions (Chapter 7). These results highlight the potential importance of predators in maintaining community dynamics in estuarine planktonic communities under certain conditions. This study represents some of the first work to address these various aspects of predator-prey dynamics within the context of planktonic estuarine ecology.
- Full Text:
Ecological consequences of non-native fish invasion in Eastern Cape headwater streams
- Authors: Ellender, Bruce Robert
- Date: 2014
- Subjects: Fishery management -- South Africa -- Eastern Cape Fishes -- Conservation -- South Africa Introduced fishes -- South Africa -- Eastern Cape Introduced organisms
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/69065 , vital:29380
- Description: The introduction, spread and concomitant impacts of non-native species are a global problem. Fish are among the most widely introduced vertebrate groups, with their impacts affecting multiple levels of organisation- from individuals, populations and communities, to entire ecosystems. In South Africa, the largest perceived threat to range-restricted endemic headwater stream fishes is said to be invasion by non-native fishes, however, as is the case elsewhere, invasive impacts are often a case of risk perception rather than actual risk analysis. Two range-restricted headwater species, the Eastern Cape redfin Pseudobarbus afer and the Border barb Barbus trevelyani are redlisted by the International Union for the Conservation of Nature (IUCN) as ‘Endangered’, primarily due to invasion by non-native fishes. To investigate invasions in South Africa, and provide a quantitative estimate of the impact of non-native fishes on the two imperilled endemics, P. afer and B. trevelyani, the overall aims of this thesis were to: (A) Provide a literature review on non-native fish invasions in South Africa; (B) Using two case studies on the headwaters of the perennial Keiskamma and episodic Swartkops River systems, investigate the naturalisation-invasion continuum to provide a holistic view of the invasion process in these variable environments. The specific thesis objectives were: (1) Reviewing current knowledge of invasive impacts of non-native fishes in South Africa; (2) Investigating invasibility of headwater stream environments by non-native fishes; (3) Determining the establishment success of non-native fishes, (4) Assessing the spatial and temporal impacts of invasion; (5) Understanding mechanisms responsible for non-native fish impacts; (6) Investigating the threat of non-native fish invasion on the genetic diversity of two the two headwater fishes, P. afer and B. trevelyani. Results from the literature review of fish invasions (Chapter 1) showed that South Africa has a long history of non-native fish introductions, spanning two and a half centuries. Currently, 55 species have been introduced or translocated. Many of these introduced species have become fully invasive (36%). Their impacts also span multiple levels of biological organisation. There was a general paucity of studies on fish invasions (38 studies), however, of those conducted, reviewed studies placed emphases on invasive impacts (25 studies) and the transport, introduction, establishment and spread stages of the invasion process were largely ignored. The two study systems, the Swartkops and Keiskamma Rivers, were heavily invaded and numbers of introduced species surpassed that of natives (Chapter 2, 3 and 5). Headwater streams had varying invasibility and a number of non-native species were successfully established (Chapter 2, 3, 5 and 6). The remainder of the invasions were casual incursions into headwater streams from source populations in mainstream and impoundment environments which were invasion hotspots. Irrespective of establishment, four predatory invaders (largemouth bass Micropterus salmoides, smallmouth bass M. dolomieu, brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss) impacted heavily on native fish communities (Chapter 3, 4 and 5). Two broad types of invasion were documented, top down invasion by non-native O. mykiss and S. trutta and upstream invasion by M. salmoides and M. dolomieu (Chapter 3 and 5). Their impacts included changes in community structure, extirpation from invaded stream reaches resulting in contracted distribution, and isolation and fragmentation of native fish populations. The impacts of non-native predatory fishes were particularly acute for P. afer and B. trevelyani. Where non-native predatory fish occurred, P. afer and B. trevelyani had been extirpated (Chapter 3 and 5). As a result both native species exhibited contracted distributions (>20% habitat loss due to invasion). Upstream invasion by centrarchids isolated and fragmented P. afer populations into headwater refugia, while top down invasion by salmonids excluded B. trevelyani from invaded, more pristine stream reaches, by forcing the species into degraded unsuitable lower stream reaches. Predation also disrupted population processes such as adult dispersal for P. afer, and centrarchid-invaded zones acted as demographic sinks, where adults dispersing through invaded reaches were rapidly depleted. While the Mandela lineage of P. afer exhibited little within or between drainage genetic structuring, B. trevelyani was >4% divergent between drainages, and up to 2% divergent between streams within the Keiskamma River system (Chapter 7). The distribution of genetic diversity for B. trevelyani also indicated that the loss of diversity was imminent without immediate conservation interventions. This thesis has provided conclusive evidence that native fishes are vulnerable to invasion and that non-native predatory fishes have significant impacts on native fishes in Eastern Cape headwater streams. If management and conservation measures are implemented, the unwanted introduction and spread of non-native fishes may be restricted, allowing native fishes opportunities for recovery.
- Full Text:
Electrospun fiber based colorimetric probes for aspartate aminotransferase and I7ß-estradiol
- Authors: Pule, Bellah Oreeditse
- Date: 2014
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54869 , vital:26623
- Description: Fabrication, characterization and application of electrospun polymer composite based colorimetric probes are presented in this thesis. The first part of the thesis involved the development of a protocol for in situ reduction of gold trication (Au³+) into metallic gold atoms with sodium borohydride. The prepared PS-Au NPs showed an SPR band at 542 nm. Furthermore the absorbance of the colloidal Au NPs in polystyrene exhibited a good linear correlation (r2 = 0.9934) to E2 concentration in the range 5 to 50 ppb. The lowest naked eye detection limit was found to be 0.5 ppb and could further be easily monitored by UV-vis spectrophotometer. Upon interaction with E2 Au NPs aggregated to give nanoparticle clusters, confirmed through TEM analysis. Different concentrations of Au NPs were found to have a significant effect on the conductivity of the PS-Au NPs solution. At low concentrations of Au NPs (0.002, 0.015 and 0.025% w/v) PS-Au NPs solution could be electrospun without clogging. The FE-SEM images showed a non-beaded morphology of PS-Au NPs composite fibers. Upon interaction of the colorimetric probe strips with various E2 concentrations it was observed that with increasing E2 concentrations (50 ng/ml to 1000 µg/ml) the colour of the probe changed gradually from white to shades of pink and eventually to shades of blue at higher E2 concentrations. The visible cut-off concentration was 100 ng/ml. The second component of the thesis focussed on the development of diazonium dye-nylon 6 colorimetric probe for aspartate aminotransferase. At optimal pH 7.4 the enzyme was stable, highly active and catalyzed a reaction that was susceptible to detailed kinetic analysis by continuous optical methods. The KM values for L-aspartate, a- ketoglutarate and oxaloacetate were 2.60, 0.59 and 0.066 mM, respectively. On the basis of these KM values the solid-state colorimetric probe was developed. A colour change occurred when an electrospun dye-N 6 probes were exposed to visibly detectable concentrations of oxaloacetate, an AST-catalyzed reaction product. While monitoring AST activity at 530 run, a linear relation was obtained between oxaloacetate concentrations ranging from 0.4 - 7.4 µg/ml. Naked eye detection limit of 2.4 µg/ml oxalaoacetate equivalence of 10 times the normal AST activity was attained. The colorimetric probe was in addition, tested against co-substrates aspartate, ketoglutarate and a variety of other compounds such as alanine, pryruvate, as well as glutamic, malaic and succinic acids known to interfere with AST activity. Each compound elicited a distinct and unambiguous colour change upon interaction with the colorimetric probe. Further X-ray powder diffraction (XRD), duNouy ring tensiometer, Brunauer- Emmett- Teller (BET) and energy dispersive X-ray spectroscopy (EDS/EDX) characterization confirmed composition and stability of the colorimetric probes. Colorimetric probes developed in this thesis are relatively cost effective, simple and "rugged" for measurement of analytes with visual detection without sample pretreatment in matrices, such as plasma and dairy effluents. The probes warrant further investigation as they have shown potential and offer a promising solid-state platform for both clinical diagnostics and environmental monitoring.
- Full Text:
Electrospun fibre based colorimetric probes for biological molecules
- Authors: Mudabuka, Boitumelo
- Date: 2014
- Subjects: Nanofibers , Vitamin C , Dopamine
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4535 , http://hdl.handle.net/10962/d1016354
- Description: The thesis reports the use of electrospun nanofibres as a platform for the development of colorimetric probes. Three colorimetric probes in the form of electrospun nanofibre test strips were developed for the selective detection of ascorbic acid and dopamine because they are crucial biomolecules for physiological processes in human metabolism and usually coexist in biological samples. The simultaneous detection of the biomolecules is very important as their abnormal concentration levels would lead to diseases such as Parkinson's and schizophrenia. Different methods of incorporating detector agents into the nanofibre were exploited for the detection of the biomolecules. The methods included physical incorporation of nanoparticles, covalent bonding of ligand/dyes through surface modification of the fibres. The first colorimetric test strip for ascorbic acid was based on copper-gold alloy nanoparticles prepared in-situ and hosted in nylon6. The test strip showed selectivity in detecting ascorbic acid in the pH range 2 – 7. The suitability of fibres in hosting copper-gold alloy nanoparticles for the colorimetric detection of ascorbic acid was investigated using nylon6, poly(vinyl benzyl chloride)-styrene and cellulose acetate based test strips. All the test strips exhibited leaching and the nylon6 based test strip was found to be thermally stable up to 60 ˚C. The colorimetric performance of the test strips was maintained and neither was colour decay exhibited after 10 months of storage in a shelf. The test strip achieved an eye-ball limit of detection of 1.76 x10-2 mg L-1 and its suitability was demonstrated by the determination of ascorbic acid in fruit juices, urine, serum, and vitamin C tablets. The second colorimetric test strip for ascorbic acid and dopamine employed prussian blue synthesised in-situ in nylon6. Ascorbic acid turned the deep blue test strip to light blue at pH 3, and a faded navy blue colour at a pH range of 6 - 7 while dopamine changed the strip to purple at the same pH range. The versatility of the test strip was demonstrated by detecting ascorbic acid in commercial fruit juices as well as by detecting ascorbic acid as well as dopamine in fortified urine. The eye-ball detection limit of the Prussian blue test strip for ascorbic acid and dopamine was 17.6 mg L-1 and 18.9 mg L-1, respectively. The third method involved a covalent approach, where poly(vinylbenzyl chloride) nanofibers were post functionalised with 2-(2′-pyridyl)-imidazole and iron(III) for the selective detection of ascorbic acid and dopamine. The eye-ball detection limit for ascorbic acid and dopamine was 17.6 mg L-1 and 18.9 mg L-1, respectively. The test strip was selective for dopamine, but the detection of ascorbic acid suffered from interference by glutathione. The application of the test strips was nevertheless demonstrated by the detection of ascorbic acid in fruit juices and dopamine in fortified urine. The developed test strips employing the three approaches were applied without sample pre-treatment and use of supporting equipment.
- Full Text:
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
- Full Text:
Empathy in the time of ecological apartheid : a social sculpture practice-led inquiry into developing pedagogies for ecological citizenship
- Authors: McGarry, Dylan Kenneth
- Date: 2014
- Subjects: Education -- Philosophy , Social learning , Environmental education , Arts in education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1985 , http://hdl.handle.net/10962/d1013154
- Description: Considering the ecological crisis and the increased disconnection between human beings and nature, this study attempts to find the social and aesthetic educational response needed for developing ecological citizenship for the 21st century. In this transdisciplinary study I articulate what at first seems a clumsy attempt to enable the capacities of the embodied ecological citizen, and which later emerges as an alchemical ‘social sculpture’ approach to learning that expands the range of capacities available to the citizen and the citizen’s immediate community. This learning bridges the gap between purely biocentric and technocentric forms of education, and addresses the ambiguity of concepts and forms of action such as ‘sustainability’. My primary focus is enabling both communal and personal forms of agency: new ways of 'doing’ and 'being' in the world as it changes radically. I argue that this demands constantly reflecting on and engaging without understanding, place and perception of the problems we see. Attending to a call for the importance of complex learning processes, that deepens our understanding of sustainability, and the need for methodological and pedagogical approaches to accessible forms of learning socially in the era of climate change and environmental degradation, this study offers a particular insight into the education of an ecological citizen. In particular I examine a form of learning that enables individuals to explore relationships between themselves and their ecologies (both physical and social), and that encourages personal forms of knowing so that each person’s values can be cultivated within the experience and intuitive expression from both inner and outer realities. Central to my research focus is addressing the difficulties inherent in ‘ecological apartheid’, which is defined as a growing separation of relationships that include the human being’s relationship with the natural world, as well as disconnections experienced within one’s own inner and outer capacities. Subsequently I investigate forms of learning that encourage agency that most appropriately enable citizens to respond personally to both inner and outer forms of disconnection. ‘Personal’ and ‘relational agency’ are defined and investigated through an initial twelve-month collaborative participatory contextual profiling exploratory research period in South Africa (phase A), where I explore various forms of multiple-genre creative social learning practice that develop an accessible set of methodologies and pedagogies for the ecological citizen. Through this exploratory research, I place significance in the relatively unknown field of social sculpture, which I investigate through a self-made apprenticeship with Shelley Sacks, an expert in the field. This is documented through a rigorous ethnographic inquiry over a period of 18 months. Following this I undertake another two-year collaborative, practice-based research study across South Africa (phase B: 17 towns, with a total of 350 citizens) and eventually abroad (United Kingdom, Germany, USA and Belgium).The focus of this study was the implementation of a collaboratively developed citizen learning practice entitled Earth Forum developed by Shelley Sacks as a progression from her work “Exchange Values: voices of insivible lives” and my collaboative exploration into Earth Forum and its further development draws heavily from social sculpture methods obtained during the apprenticeship, and applied in 36 different incidences. I further explore the efficacy of this practice in enabling and expanding the capacities of participants, particularly those that encourage the development of personal and relational agency. This was achieved through a pedagogical development and expansion period (phase C). A primary finding through the iterative phase (phase D) was the value of imaginal contemplation, attentive listening, and empathy as capacities that enable an ecological citizen’s overall capability. I ascribed this to Nussbaum and Sen’s (1993) capability theory and the need to enable the articulation and implementation of a citizen’s valued ‘beings and doings’. Through this iterative phase, specific attention is given to listening and intuitive capacities in enabling personal and relational agency, and specifically I observed the fundamental role of imagination in this form of learning. Particularly valuable for the educational contribution of this study is the pedagogical development of the Earth Forum practice that enables an accessible, socially constructed form of learning. This contributes specifically to exploring ‘how’ social learning is undertaken, and I argue that an aesthetic approach to learning is vital for the education of the ecological citizen. I carefully describe how one can conduct collaborative practice-based research that utilises creative connective practice in agency development. This collaborative approach, with regard to learning socially and capacity development for ecological citizenship (that focuses its attention on addressing ecological apartheid and separateness), is articulated through a multiple-genred text. I found that empathetic capacity in ecological citizen education is relatively unexplored, and within listening and as well in empathy theory, that the role of imagination in listening and empathy development, requires greater attention. I attempt to reveal how connective practice considers aesthetic form and shape in expanding capacities of human beings, and introduce novel expanded forms of developing pedagogies that encourage personal and relational agency in the context of ecological apartheid from the artsbased field of social sculpture. Finally, I aim in this study to share the potential value found in social sculpture theory and practice into the field of environmental education and social learning through a reflection on the current context of education and social learning, and its potential enrichment via social sculpture processes.
- Full Text:
Enabling cumulative knowledge-building through teaching: a legitimation code theory analysis of pedagogic practice in law and political science
- Authors: Clarence, Sherran
- Date: 2014
- Subjects: Law -- Study and teaching (Higher) -- South Africa Political science -- Study and teaching (Higher) -- South Africa Education, Higher -- South Africa College teaching -- South Africa Knowledge, Theory of Social realism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1966 , http://hdl.handle.net/10962/d1011763
- Description: Much current research and practice in teaching and learning in higher education tends to overfocus on social aspects of education; on how rather than what students are learning. Much of this research and practice is influenced by constructivism, which has a relativist stance on knowledge, generally arguing, contra positivism, that knowledge is constructed in socio-historical contexts and largely inseparable from those who construct it and from issues of power. This leads to a confusion of knowledge with knowing, and knowledge is thus obscured as an object of study because it is only seen or understood as knowing or as a subject of learning and teaching. This ‘knowledge-blindness’ (Maton 2013a: 4) is problematic in higher education because knowledge and knowing are two separate parts of educational fields, and while they need to be brought together to provide a whole account of these fields, they also need to be analysed and understood separately to avoid blurring necessary boundaries and to avoid confusing knowledge itself with how it can be known. Being able to see and analyse knowledge as an object with its own properties and powers is crucial for both epistemological access and social inclusion and justice, because knowledge and knowledge practices are at the heart of academic disciplines in universities. Social realism offers an alternative to the dilemma brought about by constructivism’s tendency towards knowledge-blindness. Social realism argues that it is possible to see and analyse both actors within social fields of practice as well as knowledge as something that is produced by these actors but also about more than just these actors and their practices; thus knowledge can be understood as emergent from these practices and fields but not reducible to them (Maton & Moore 2010). Social realism, drawing from Roy Bhaskar’s critical realist philosophy (1975, 2008), is intent on looking at the real structures and mechanisms that lie beneath appearances and practices in order to understand the ways in which these practices are shaped, and change over time. Legitimation Code Theory is a realist conceptual framework that has, as its central aim, the uncovering and analysis of organising principles that shape and change intellectual and education fields of production and reproduction of knowledge. In other words, the conceptual tools Legitimation Code Theory offers can enable an analysis of both knowledge and knowers within relational social fields of practice by enabling the analysis of the ways in which these fields, such as academic disciplines, are organised and how knowledge and knowing are understood in educational practice. This study draws on social realism more broadly and Legitimation Code Theory specifically to develop a relatively novel conceptual and explanatory framework within which to analyse and answer its central question regarding how to enable cumulative knowledge building through pedagogic practice. Using qualitative data from two academic disciplines, Law and Political Science, which was analysed using a set of conceptual and analytical tools drawn from Legitimation Code Theory, this study shows that the more nuanced and layered accounts of pedagogy that have been generated are able to provide valuable insights into what lecturers are doing as they teach in terms of helping students to acquire, use and produce disciplinary and ‘powerful’ knowledge (Young 2008b). Further, the study demonstrates that the organising principles underlying academic disciplines have a profound effect on how the role of the knower and the place or purpose of knowledge is understood in pedagogy and this affects how the pedagogy is designed and enacted. This study has argued that if we can research pedagogy rigorously using tools that allow us to see the real mechanisms and principles influencing and shaping it, and if we can reclaim the role of disciplinary knowledge as a central part of the pedagogic relationship between lecturer and students, then we can begin to see how teaching both enables and constrains cumulative learning. Further, we can change pedagogy to better enable cumulative learning and greater epistemological access to disciplinary knowledge and related practices for greater numbers of students. The study concludes by suggesting that the conceptual tools offered by Legitimation Code Theory can provide academic lecturers with a set of tools that can begin to enable them to 'see' and understand their own teaching more clearly, as well as the possible gaps between what they are teaching and what their students are learning. This study argues that a social realist approach to the study of pedagogy such as the one used here can begin not only to enable changes in pedagogy aimed at filling these gaps but also begin to provide a more rigorous theoretical and practical approach to analysing, understanding and enacting pedagogic practice. This, in turn, can lead to more socially just and inclusive student learning and epistemic and social access to the powerful knowledge and ways of knowing in their disciplines.
- Full Text:
Establishing a formulation design space for a generic clobetasol 17- propionate cream using the principles of quality by design
- Authors: Fauzee, Ayeshah Fateemah Beebee
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:20983 , http://hdl.handle.net/10962/5868
- Description: The pharmaceutical industry is global, is highly regulated and is able to achieve reasonable product quality but at high cost with maximum effort. Numerous challenges face the pharmaceutical industry and include a shrinking research pipeline, less innovation, outsourcing, investments, increasing research and development costs, long approval times, growth of the generic industry, failure to understand or analyze manufacturing failure and wastage as high at fifty percent for some pharmaceutical products. An efficient and flexible pharmaceutical sector should be able to consistently produce high quality pharmaceutical products at a reduced cost with minimal waste. As a result, Food and Drug Administration (FDA) and other agencies such as the International Conference on Harmonization (ICH) have embraced a “Quality by Design” (QbD) paradigm and this has become the “desired state” so as to shift manufacturing from being empirical to a science, engineering, and risk based approach. QbD is a systematic approach for the development of high quality pharmaceutical dosage forms that begins with predefined objectives based on the premise that quality must be built into and not tested into a product. QbD together with the establishment of a design space for dosage forms is a fairly new concept and there is limited published data on QbD concepts that report the entire process of identifying Critical Quality Attributes (CQA), design of a formulation and manufacturing process to meet product CQA, understanding the impact of material attributes and process parameters on product CQA, identification and controlling sources of variability in materials and processes that affect the CQA of a product and finally establishing, evaluating and testing a design space using both in vitro and in vivo approaches to assure that a product of consistent quality can always be produced. The objective of these studies was to implement a QbD approach to establish a design space for the development and manufacture of a safe, effective, stable generic formulation containing 0.05% w/w clobetasol 17-propionate (CP) that had similar in vitro and in vivo characteristics to an innovator product, Dermovate® (Sekpharma® Pty Ltd, Sandton, Gauteng, RSA). Such a product would pose a minimal risk of failure when treating severe skin disorders such as seborrhoeic dermatitis, extreme photodermatitis and/or severe psoriasis in HIV/AIDS patients in Southern Africa.
- Full Text:
Evaluating the post-implementation effectiveness of selected household water treatment technologies in rural Kenya
- Authors: Onabolu, Boluwaji
- Date: 2014
- Subjects: Water-supply, Rural -- Kenya , Sanitation, Rural -- Kenya , Sanitation, Household -- Kenya , Drinking water -- Purification -- Kenya , Drinking water -- Microbiology -- Kenya , Health behavior -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6045 , http://hdl.handle.net/10962/d1013145
- Description: Water, sanitation and hygiene-related diseases are responsible for 7% of all deaths and 8% of all disability adjusted live years (DALYs), as well as the loss of 320 million days of productivity in developing countries. Though laboratory and field trials have shown that household water treatment (HWT) technologies can quickly improve the microbiological quality of drinking water, questions remain about the effectiveness of these technologies under real-world conditions. Furthermore, the value that rural communities attach to HWT is unknown, and it is not clear why, in spite of the fact that rural African households need household water treatment (HWT) most, they are the least likely to use them. The primary objective of this multi-level study was to assess the post-implementation effectiveness of selected HWT technologies in the Nyanza and Western Provinces of Kenya. The study was carried out in the rainy season between March and May, 2011 using a mixed method approach. Evidence was collected in order to build a case of evidence of HWT effectiveness or ineffectiveness in a post-implementation context. A quasi-experimental design was used first to conduct a Knowledge, Attitudes and Practices (KAP) survey in 474 households in ten intervention and five control villages (Chapter 3). The survey assessed the context in which household water treatment was being used in the study villages to provide real-world information for assessing the effectiveness of the technologies. An interviewer-administered questionnaire elicited information about the water, sanitation and hygiene-related KAP of the study communities. A household water treatment (HWT) survey (Chapter 4) was carried out in the same study households and villages as the KAP study, using a semi-structured questionnaire to gather HWT adoption, compliance and sustained use-related information to provide insight into the perceived value the study households attach to HWT technologies, and their likelihood of adoption of and compliance with these technologies. The drinking water quality of 171 (one quarter of those surveyed during KAP) randomly selected households was determined and tracked from source to the point of use (Chapter 5). This provided insights into HWT effectiveness by highlighting the need for HWT (as indicated by source water quality) and the effect of the study households’ KAP on drinking water quality (as indicated by the stored water quality). Physico-chemical and microbiological water quality of the nineteen improved and unimproved sources used by the study households was determined, according to the World Health Organisation guidelines. The microbiological quality of 291 water samples in six intervention and five control villages was determined from source to the point-of-use (POU) using the WHO and Sphere Drinking Water Quality Guidelines. An observational study design was then used to assess the post-implementation effectiveness of the technologies used in 37 households in five intervention villages (Chapter 6). Three assessments were carried out to determine the changes in the microbiological quality of 107 drinking water samples before treatment (from collection container) and after treatment (from storage container) by the households. The criteria used to assess the performance of the technologies were microbial efficacy, robustness and performance in relation to sector standards. A Quantitative Microbial Risk Assessment (QMRA) was then carried out in the HWT effectiveness study households to assess the technologies’ ability to reduce the users’ exposure to and probability of infection with water-borne pathogens (Chapter 7). The KAP survey showed that the intervention and control communities did not differ significantly in 18 out of 20 socio-economic variables that could potentially be influenced by the structured manner of introducing HWT into the intervention villages. The majority of the intervention group (IG) and the control group (CG) were poor or very poor on the basis of household assets they owned. The predominant level of education for almost two-thirds of the IG and CG respondents was primary school (completed and non-completed). Though very few were unemployed in IG (8.07%) and CG (14.29%), the two groups of respondents were predominantly engaged in subsistence farming — a low income occupation. With regard to practices, both groups had inadequate access to water and sanitation with only one in two of the households in both IG and CG using improved water sources as their main drinking water source in the non-rainy season. One in ten households in both study groups possessed an improved sanitation facility, though the CG was significantly more likely to practice open defecation than the IG. The self-reported use of soap in both study groups was mainly for bathing and not for handwashing after faecal contact with adult or child faeces. Despite the study groups' knowledge about diarrhoea, both groups showed a disconnection between their knowledge about routes of contamination and barriers to contamination. The most frequent reason for not treating water was the perceived safety of rain water in both the IG and CG. , The HWT adoption survey revealed poor storage and water-handling practices in both IG and CG, and that very few respondents knew how to use the HWT technologies correctly: The IG and CG were similar in perceived value attached to household water treatment. All HWT technologies had a lower likelihood of adoption compared to the likelihood of compliance indicators in both IG and CG. The users’ perceptions about efficacy, time taken and ease of use of the HWT technologies lowered the perceived value attached to the technologies. The assessment of the drinking water quality used by the study communities indicated that the improved sources had a lower geometric mean E. coli and total coliform count than the unimproved sources. Both categories of sources were of poor microbiological quality and both exceeded the Sphere Project (2004) and the WHO (2008) guidelines for total coliforms and E. Coli respectively The study communities’ predominant drinking water sources, surface water and rainwater were faecally contaminated (geometric mean E. coli load of 388.1±30.45 and 38.9±22.35 cfu/100 ml respectively) and needed effective HWT. The improved sources were significantly more likely than the unimproved sources to have a higher proportion of samples that complied with the WHO drinking water guidelines at source, highlighting the importance of providing improved water sources. The lowest levels of faecal contamination were observed between the collection and storage points which coincided with the stage at which HWT is normally applied, suggesting an HWT effect on the water quality. All water sources had nitrate and turbidity levels that exceeded the WHO stipulated guidelines, while some of the improved and unimproved sources had higher than permissible levels of lead, manganese and aluminium. The water source category and the mouth type of the storage container were predictive of the stored water quality. The active treater households had a higher percentage of samples that complied with WHO water quality guidelines for E. coli than inactive treater households in both improved and unimproved source categories. In inactive treater households, 65% of storage container water samples from the improved sources complied with the WHO guidelines in comparison to 72% of the stored water samples in the active treater households. However the differences were not statistically significant. The HWT technologies did not attain sector standards of effective performance: in descending order, the mean log10 reduction in E. coli concentrations after treatment of water from unimproved sources was PUR (log₁₀ 2.0), ceramic filters (log₁₀ 1.57), Aquatab (log₁₀ 1.06) and Waterguard (log₁₀ 0.44). The mean log10 reduction in E. coli after treatment of water from improved sources was Aquatab (log₁₀ 2.3), Waterguard (log₁₀ 1.43), PUR (log₁₀ 0.94) and ceramic filters (log₁₀ 0.16). The HWT technologies reduced the user’s daily exposure to water-borne pathogens from both unimproved and improved drinking water sources. The mean difference in exposure after treatment of water from unimproved sources was ceramic filter (log₁₀ 2.1), Aquatab (log₁₀ 1.9), PUR (log₁₀ 1.5) and Waterguard (log₁₀ 0.9), in descending order. The mean probability of infection with water-borne pathogens (using E.coli as indicator) after consumption of treated water from both improved and unimproved sources was reduced in users of all the HWT technologies. The difference in reduction between technologies was not statistically significant. The study concluded that despite the apparent need for HWT, the study households’ inadequate knowledge, poor attitudes and unhygienic practices make it unlikely that they will use the technologies effectively to reduce microbial concentrations to the standards stipulated by accepted drinking water quality guidelines. The structured method of HWT promotion in the intervention villages had not resulted in more hygienic water and sanitation KAP in the IG compared to the CG, or significant differences in likelihood of adoption and compliance with the assessed HWT technologies. Despite attaching a high perceived value to HWT, insufficient knowledge about how to use the HWT technologies and user concerns about factors such as ease of use, accessibility and time to use will impact negatively on adoption and compliance with HWT, notwithstanding their efficacy during field trials. Even though external support had been withdrawn, the assessed HWT technologies were able improve the quality of household drinking water and reduce the exposure and risk of water-borne infections. However, the improvement in water quality and reduction in risk did not attain sector guidelines, highlighting the need to address the attitudes, practices and design criteria identified in this study which limit the adoption, compliance and effective use of these technologies. These findings have implications for HWT interventions, emphasising the need for practice-based behavioural support alongside technical support.
- Full Text:
Exploring teaching proficiency in geometry of selected effective mathematics teachers in Namibia
- Authors: Stephanus, Gervasius Hivengwa
- Date: 2014
- Subjects: Mathematics -- Study and teaching (Secondary) -- Namibia , Geometry -- Study and teaching (Secondary) -- Namibia , Effective teaching -- Namibia , Mathematics teachers -- Education (Secondary) -- Namibia , Education, Secondary -- Namibia , Mathematics teachers -- Training of -- Namibia
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1976 , http://hdl.handle.net/10962/d1013012
- Description: Quality mathematics education relies on effective pedagogy which offers students appropriate and rich opportunities to develop their mathematical proficiency (MP) and intellectual autonomy in learning mathematics. This qualitative case study aimed to explore and analyse selected effective mathematics teachers' proficiency in the area of geometry in five secondary schools in five different Namibia educational regions. The sample was purposefully selected and comprised five mathematics teachers, identified locally as being effective practitioners by their peers, Education Ministry officials and the staff of the University of Namibia (UNAM). The schools where the selected teachers taught were all high performing Namibian schools in terms of students' mathematics performance in the annual national examinations. The general picture of students' poor performance in mathematics in Namibia is no different to other sub-Saharan countries and it is the teachers who unfortunately bear the brunt of the criticism. There are, however, beacons of excellence in Namibia and these often go unnoticed and are seldom written about. It is the purpose of this study to focus on these high achievers and analyse the practices of these teachers so that the rest of Namibia can learn from their practices and experience what is possible in the Namibian context. The mathematical content and context focus of this study was geometry. This qualitative study adopted a multiple case study approach and was framed within an interpretive paradigm. The data were collected through individual questionnaires, classroom lesson observations and in-depth open-ended and semi-structured interviews with the participating teachers. These interviews took the form of post lesson reflective and stimulated recall analysis sessions. An adapted framework based on the Kilpatrick, Swafford and Findell's (2001) five strands of teaching for MP was developed as a conceptual and analytical lens to analyse the selected teachers' practice. The developed coding and the descriptive narrative vignettes of their teaching enabled a qualitative analysis of what teachers said contributed to their effectiveness and how they developed MP in students. An enactivist theoretical lens was used to complement the Kilpatrick et al.'s (2001) analytical framework. This enabled a deeper analysis of teacher teaching practice in terms of their embodied mathematical knowledge, actions and interactions with students. procedural fluency (PF) and productive disposition (PD), were addressed regularly by all five participating teachers. Evidence of addressing either the development of students' strategic competence (SC) or adaptive reasoning (AR) appeared rarely. Of particular interest in this study was that the strand of PD was the glue that held the other four strands of MP together. PD was manifested in many different ways in varying degrees. PD was characterised by a high level of content knowledge, rich personal experience, sustained commitment, effective and careful preparation for lessons, high expectations of themselves and learners, collegiality, passion for mathematics and an excellent work ethic. In addition, the teachers' geometry teaching practices were characterised by making use of real-world connections, manipulatives and representations, encouraging a collaborative approach and working together to show that geometry constituted a bridge between the concrete and abstract. The findings of the study have led me, the author, to suggest a ten (10) principles framework and seven (7) key interrelated factors for effective teaching, as a practical guide for teachers. This study argues that the instructional practices enacted by the participating teachers, who were perceived to be effective, aligned well with practices informed by the five strands of the Kilpatrick et al.'s (2001) model and the four concepts of autopoesis, co-emergence, structural determinism and embodiment of the enactivist approach. The study concludes with recommendations for effective pedagogical practices in the teaching of geometry, and opportunities for further research.
- Full Text:
Fishing for resilience : herbivore and algal dynamics on coral reefs in Kenya.
- Authors: Humphries, Austin Turner
- Date: 2014
- Subjects: Coral reef conservation -- Kenya , Coral reef ecology -- Kenya , Coral reef biology -- Kenya , Coral reef fishes -- Kenya , Herbivores -- Kenya , Algae -- Control -- Kenya , Fishery management -- Kenya
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5877 , http://hdl.handle.net/10962/d1013147
- Description: Herbivory is a key process that mediates the abundance of primary producers and community composition in both terrestrial and aquatic ecosystems. On tropical coral reefs, changes in herbivory are often related to phase shifts between coral-dominance and dominance by seaweeds, or foliose macroalgae. Resilience or capacity to resist and reverse such phase shifts is, therefore, viewed as a critical function on coral reefs. This thesis used grazer exclusion and assay experiments at six sites within three different fisheries management regimes in Kenya to identify the impacts of herbivores (sea urchins and fishes) on algal dynamics in the context of coral reef resilience. First, I examined the grazing rates necessary to prevent phase shifts by quantifying consumption and algal production. Here, I found that, over a 390-day experiment, at least 50 percent of algal production must be consumed to avoid accumulation of algal biomass. Using video observations, I also showed that scraping parrotfishes remove more algae (per unit of fish biomass) than previously assumed, and that sea urchins, if released from predation, have similar impacts to fishes. Then I focused on algal succession, and found that sea urchins and fishes have different effects that are mediated by their abundances and species composition. Where sea urchins were less abundant and parrotfishes absent (e.g. young fisheries closures), progression of algae from turfs to early and then late successional macroalgae occurred rapidly and within 100 days. I then turned my focus to the removal of already established macroalgae (grown for > 1 yr in the absence of herbivores) and showed that sea urchins and browsing fishes were able to remove significant amounts of macroalgae where either herbivore was abundant. However, using multiple-choice selectivity assays and in situ video recordings, I found that browsing fishes fed very selectively with low overlap in diet among species, leading to low functional redundancy within a high diversity system. Finally, using long-term survey data (from 28 sites) to build a 43-year chronosequence, I showed that it is possible that the effects of herbivory will not be constant across transitions from open fishing to fishery closures through non-linear grazing intensity. Therefore, increases in herbivory within fisheries closures may not be immediate and may allow a window of opportunity for algae to go from turf to unpalatable macroalgae until scraping and browsing fishes fully recover from fishing (~ 20 years). The findings in this thesis are novel and raise concern over the potential implications of the slow recovery of parrotfishes or, given lower than expected functional redundancy in grazing effects, the absence of even one browsing fish species in fisheries closures. Overall, this thesis highlights the importance of herbivore community dynamics in mediating interactions among algae, and provides new insights for conservation and management actions that attempt to bolster the resilience of coral reefs.
- Full Text:
Inter-individual variability and phenotypic plasticity : the effect of the environment on the biogeography, population structure, ecophysiology and reproduction of the sandhoppers Talorchestia capensis and Africorchestia quadrispinosa
- Authors: Baldanzi, Simone
- Date: 2014
- Subjects: Phenotypic plasticity -- Research -- Africa, Southern Talitridae -- Research -- Africa, Southern Amphipoda -- Research -- Africa, Southern Climatic changes -- Environmental aspects -- Africa, Southern Marine biology -- Africa, Southern Adaptation (Biology) -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5846 , http://hdl.handle.net/10962/d1011447
- Description: Climatic envelope models focus on the climatic variables affecting species or species assemblages, and are important tools to investigate the effect of climate change on their geographical ranges. These models have largely been proposed in order to make successful predictions on species‘ persistence, determining which variables are likely to induce range expansion, contraction, or shifting. More recent models, including the ability and the cost for individuals to respond promptly to an environmental stimulus, have revealed that species may express phenotypic plasticity able to induce adaptation to the new environment. Consequently, understanding how species evolve to a changing climate is fundamental. From this perspective, investigating intraspecific responses to an environmental variable may contribute to better understanding and prediction of the effect of climate change on the geographical range and evolution of species, particularly in the case of widespread species. In this context, the present study aimed at establishing how environmental variables (focussing mainly on temperature) may have contributed to shape the spatial distribution, physiology, reproductive biology and connectivity of two species of Southern African sandhoppers (Talorchestia capensis and Africorchestia quadrispinosa, Amphipoda, Talitridae). Most of the work was carried out on T. capensis, due to its widespread spatial distribution. A first investigation of the biogeography of T. capensis and A. quadrispinosa, revealed that, for both species, spatial patterns of abundance, size and sex ratio were not explained by the Abundant Centre Hypothesis (greater abundance at the core of a spatial range), but rather guided by bio-physical forces. Precisely, the abundance of sandhoppers was driven by the morphodynamic state of the beach, salinity and temperatures, with strong differentiation among sites that reflected local environmental conditions. In support of these findings, strong population structure in the genetics of T. capensis was found (three main groups) when investigating its phylogeography and genetic connectivity. Although such defined structure may suggests cryptic speciation, the concomitant within-population variation in the COX1 region of mtDNA, also highlighted the importance of individual genetic variability. High individual variability was also found in the response of T. capensis to temperature, both in its physiology (thermal plasticity) and its reproductive biology (maternal effects). Since temperature is one of the main variables affecting the coastal marine systems of southern Africa and the metabolism of animals in general, its effect on the physiology and reproduction of T. capensis was therefore investigated. Thermal responses to increasing/decreasing temperatures were assessed for separated populations of T. capensis. Individual variability was reported in the oxygen consumption of T. capensis in response to temperature (high variation around the means, especially for increasing temperatures). Among population differences in thermal sensitivity were significantly correlated with air temperature variability experienced over the past 23 years, highlighting the importance of historical temperature fluctuations to the current thermal physiology of these sandhoppers. Temperature also had an important effect on the reproductive plasticity of T. capensis. Different temperatures induced mothers to adjust the size of their offspring (i.e. egg size), with larger eggs produced at lower temperatures. Interestingly, females showed strongly significant among individual variation in the size of the eggs. Given the importance of understanding rapid responses of organisms to climate change and considering the fundamental role played by phenotypic plasticity in evolution, the overall study revealed the significance of individual plasticity and variability in response to the environment and highlighted its importance. Particularly, studying the thermal physiology of separated populations and understanding within population reproductive plasticity in response to temperature, helped to clarify how differences among individual responses have important consequences at the population level, possibly explaining the widespread distribution of T. capensis.
- Full Text:
Investigating the English vocabulary needs, exposure, and knowledge of isiXhosa speaking learners for transition from learning to read in the Foundation Phase to reading to learn in the Intermediate Phase : a case study
- Authors: Sibanda, Jabulani
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1968 , http://hdl.handle.net/10962/d1011790
- Description: The nature of learners' transition from Grade 3 to Grade 4 has serious and far reaching ramifications for their educational success in the subsequent grades. This is true of the South African education system, as it is for several other education contexts. The challenge that complicates the transition is largely a lexical one. It is with that understanding that the present study aimed to do three things namely: to determine the vocabulary needs of Grade 3 learners for transitioning to Grade 4; to establish the extent to which Grade 3 isiXhosa speaking learners are exposed to, and prepared for, the acquisition of that requisite vocabulary; and to establish the extent of Grade 4 learners' knowledge of that vocabulary at the beginning of the year. The vocabulary needs of Grade 3 learners for the transition to Grade 4 were determined from the Grade 4 subject textbook corpus. Word frequency was the criterion used to determine the usefulness and critical importance of a word for the transition. The AntConc concordance software program was used to generate word frequencies. Words with high frequency across the different subject areas, which were confirmed as high frequent in four other known word lists, were considered as constituting the vocabulary needs of learners at the verge of this significant transition. The extent of learners' preparedness for transitioning to Grade 4 in terms of their vocabulary exposure and vocabulary instruction was determined through teacher interviews, classroom observations, analysis of teacher classroom talk, analysis of the exposure and recycling of high frequent vocabulary in Grade 3 reading materials and classroom print. From these diverse sources, findings point to a paucity in both the exposure and recycling of the requisite vocabulary in these sources of classroom language input. Classroom observations and teacher interviews attest to lack of deliberate vocabulary instruction in the Grade 3 English First Additional Language lessons. The only extensive coverage of the requisite vocabulary was in the Grade 3 reading materials which included Big books, Readers and Workbooks. The Grade 4 learners' knowledge of the 60 high frequency words was tested through nine vocabulary tests, three of which tested their knowledge of word recognition, three tested passive word knowledge and the remaining three tested learners' active word knowledge. All the Grade 4 learners in the ten participating schools (297) were tested. Performance in the tests indicated that Grade 4 learners' knowledge of words requisite for reading to learn was low. That observation was consistent with an analysis of learners' performance per school, per district, per word, per test and per word bands. Tests of word recognition were done better than those of passive word knowledge and active word knowledge. Particularly problematic was test 4 which tested learners' knowledge of definition of words.
- Full Text: