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Formulation, development and assessment of efavirenz-loaded lipid nanocarriers

  • Authors: Makoni, Pedzisai Anotida
  • Date: 2014
  • Subjects: Nanomedicine , Drug delivery systems , Antiretroviral agents Psychotropic effects , AIDS dementia complex
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10962/209981 , vital:47448
  • Description: The feasibility of incorporating efavirenz (EFV) into innovative solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) using the hot high-pressure homogenization (HHPH) technique was investigated in an attempt to address the shortcomings in therapy associated with the use of conventional dosage forms. The shortcomings include the unpalatable taste of API in solution, instability in the presence of light when in solution and psychiatric side effects of the API. In particular, sustained release approaches may reduce or limit the incidence of adverse psychiatric effects of EFV and alleviate Acquired Immune Deficiency Syndrome (AIDS)-related complications such as AIDS Dementia Complex (ADC) in patients, ultimately improving their quality of life. Prior to initiating pre-formulation, formulation development and optimization studies of EFV-loaded SLN and/or NLC, Response Surface Methodology (RSM) in conjunction with central composite design (CCD), was used to develop and validate suitable methods for the quantitative determination of EFV in pharmaceutical formulations and for monitoring EFV release from SLN and/or NLC in vitro. Simple, accurate, precise, sensitive and stabilityindicating reversed phase-high performance liquid chromatography (RP-HPLC) methods with UV and electrochemical (EC) detection were developed, validated and optimized for in vitro analysis of EFV in formulations. On the basis of risk-to-benefit ratio the RP-HPLC method with UV detection was selected as the most suitable for the quantitative determination of EFV in pharmaceutical formulations, and was applied to in vitro release studies of EFV from SLN and/or NLC. Pre-formulation studies were undertaken to investigate the thermal stability of EFV so as to facilitate the selection of lipid excipients for the manufacture of nanocarriers, and to establish their compatibility with EFV. It was found that EFV was thermostable up to a temperature of approximately 200°C, indicating that HHPH could be used for the manufacture of EFV-loaded SLN and/or NLC. Lipid screening revealed that EFV is highly soluble in solid and liquid lipids, with glyceryl monostearate and Transcutol® HP showing the best solubilizing potential for EFV. Glyceryl monostearate exists in a stable β-modification prior to exposure to heat, but exists in the α-polymorphic modification following exposure to heat. It was established that the addition of Transcutol® HP to glyceryl monostearate revealed the co-existence of the α- and β’-polymorphic modifications, thereby revealing the existence of the modifications in NLC produced from the optimum lipid combination. Furthermore, an investigation of binary mixtures of EFV/glyceryl monostearate and glyceryl monostearate/Transcutol® HP, in addition to eutectic mixtures of EFV, glyceryl monostearate and Transcutol® HP, revealed no interaction between EFV and the lipids selected for the production of the nanocarriers. Due to the significantly higher solubility of EFV in Transcutol® HP than in to glyceryl monostearate, NLC are most likely to have a higher LC and EE than SLN. In addition, the existence of both the α- and β’-polymorphic modifications in the binary mixture of the lipid implies that EFV expulsion on prolonged storage is unlikely to occur from NLC when compared to SLN. Consequently formulation development and optimization studies of SLN and NLC were performed to investigate the potential to deliver EFV from a novel technology with an appropriate LC and EE for EFV. Tween®80 was selected for use in these formulations as the use of this surfactant facilitates the targeting of nanocarriers to the CNS. RSM in conjunction with a Box-Behnken Design (BBD) was used to establish the effects of process variables, such as number of homogenization cycles and pressure, in addition to formulation variables such as amount of EFV and Tween®80 on the particle size (PS), polydispersity index (PDI), zeta potential (ZP), visual assessment (VA) and release rate (RR) of EFV after 24 hours. In addition the LC and EE, degree of crystallinity and lipid modification, shape and surface morphology of the optimized batches were investigated to ensure that EFV-loaded SLN and NLC of desirable quality were produced. On the day of manufacture the mean PS and PDI of EFV-loaded SLN was 59.00 ± 23.16 nm and 0.382 ± 0.054 respectively. The mean PS and PDI of EFV-loaded NLC was 34.73 ± 0.7709 nm and 0.394 ± 0.027 respectively. The formulations were in the nanometer range and exhibited a narrow particle size distribution, as indicated by the PDI values. The ZP values for optimized SLN and NLC generated on the day of manufacture using HPLC grade water as the dispersion medium were -32.5 ± 4.99 mV and -22.4 ± 3.72 mV respectively. In addition the optimized batches of SLN and NLC revealed a decrease in crystallinity in comparison to bulk lipid material. DSC, WAXS and FT-IR revealed that EFV was molecularly dispersed in the nanocarriers. In addition EFV-loaded SLN existed in a single α-polymorphic form, whereas EFV-loaded NLC exhibited the co-existence of α- and β’-polymorphic forms. Generally SLN and NLC were spherically shaped when viewed under transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the day of manufacture the EE and LC of EFVloaded SLN was found to be 96.77 ± 0.453 % and 9.68 ± 1.772 % respectively. The EE and LC of EFV-loaded NLC was 99.93 ± 0.413 and 9.995 ± 0.672 respectively. The release profiles for the optimized formulations of SLN and NLC exhibited an initial burst release over the first 0-3 hours of testing, after which the release was sustained for up to 24 hours. The cumulative % EFV released over 24 hours was higher from SLN (91.5±3.423 %) than that observed for NLC (73.6±4.34 %). Stability studies performed for 8 weeks on the optimized batches of the SLN and the NLC were also conducted so as to ensure product quality. The formulations were assessed in terms of parameters considered benchmarks of stability, and included ZP, PS, PDI, LC and EE. Generally these parameters remained unchanged following storage for 8 weeks at 25°C/60% RH but showed considerable changes following storage for 8 weeks at 40°C/75% RH. These studies reveal that SLN and NLC when stored at 25°C/60% RH have the potential to be used as colloidal delivery systems for EFV that have the potential to protect EFV from photodegradation and sustain release into brain tissue. The latter will ultimately reduce or limit the incidence of adverse psychiatric effects and potentially alleviate AIDS-related complications such as ADC in patients with HIV/AIDS, ultimately improving their quality of life. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2014
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  • Date Issued: 2014

Foundation Phase teachers’ responses to curriculum change in South Africa over the past two decades: a case study of two schools

  • Authors: Nakaonga, Ruth
  • Date: 2014
  • Subjects: Curriculum change -- South Africa , Educational change -- South Africa , Education, Primary -- South Africa , Teachers -- South Africa -- Attitudes
  • Language: English
  • Type: Thesis , Masters , MEd
  • Identifier: vital:2002 , http://hdl.handle.net/10962/d1015648
  • Description: South Africa has experienced three significant curriculum reforms since 1994. The first of these replaced the ‘apartheid’ curriculum with C2005 based largely on Outcomes Based Education. In the second stage C2005 gave way to the National Curriculum Statements, a simplified version of C2005. Finally, the NCS was replaced with CAPS. This research study investigates the perceptions, attitudes and experiences of teachers implementing these curriculum changes. It focuses in particular on Foundation Phase in 2012, the year in which CAPS was implemented in that phase. It took the form of an interpretive case study, using qualitative data generating and analysis techniques. Principals and selected teachers of two primary schools in Grahamstown – an ex-Model C school and a performing ‘township’ school - were the respondents of the study. Data were generated chiefly through questionnaires and semi-structured interviews, supplemented by document analysis and observation. The findings revealed that the teachers in this study are frustrated and angry about the frequency of curriculum change in South Africa. Respondents are particularly critical of OBE and the NCS. While they welcome the need for a departure from ‘apartheid’ curricula, they feel the pedagogical underpinning of the NCS – with its emphasis on learner-centredness – disempowered them as teachers. Hence, they welcomed CAPS which seems to return to content – rather than skills and attitudes – and re-instates the teacher as the chief giver of knowledge and manager of learning.
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  • Date Issued: 2014

Frontiers of exclusion and enclusion: post-apartheid suburban social dynamics in East London, Beacon Bay

  • Authors: Buku, Luzuko
  • Date: 2014
  • Subjects: Apartheid -- South Africa -- Eastern Cape
  • Language: English
  • Type: Thesis , Masters , M Soc Sc
  • Identifier: http://hdl.handle.net/10353/1316 , vital:26545
  • Description: This dissertation deals with the nature of the black middle-class assimilation in the South African suburban space, a space that was the sole preserve of the white middle-class during apartheid. It explores the relationship between these races as they come to meet in this space and what new identities are being formed. It also explores the relationship between both the black and white suburbanites and the urban poor who stay in an adjacent area to the suburb. The study uses the Beacon Bay area, which is constituted by one of East London’s most affluent suburbs and a poor township, Nompumelelo, to show how the emergent black middle-class has managed to enter this space in the post-apartheid era. Previous studies by Richard Ballard (2004) and Grant Saff (2001) have shown how the white middle-class has always been against any form of race or class mixing. Within the suburb, the new black suburbanites in Beacon Bay appear to have been welcomed but with conditions by their fellow white counterparts. The relationship between these two races does not stretch beyond meet and greets and it is only in the second generation black middle-class that you find better and non-superficial relations with fellow white suburbanites. In the older generation, the generation that experienced apartheid, the relationship between these two races has been that of tolerance and serious escape of contact unless when necessary. The children of both white and black families, though, have a far better relationship in school and in sport than their parents. This has created another area of contact for both these races and it bears potential for meaningful integration in the suburban space. Externally as it relates to relations between the black middle-class and the urban poor, the findings show that these new black suburbanites express a similar discomfort as the white suburbanites about the urban poor’s presence in the area. This shows that the evolution of the Beacon Bay suburb, with its deep-rooted discourse of white middle-class exclusivity, has not been entirely about hatred of the urban poor necessarily but about an identity ascription of what it means to live in a suburb. Despite these realities traditional ceremonies organised by the black middle-class in the suburbs and the church appear to be playing a role in creating relations between these suburbanites and the Nompumelelo residents. This is why we have decided to use the conceptualisation of the 18th century frontier zone as the borders of segregation within the suburb and between the suburban residents and those of the township can be crossed and re-crossed.
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  • Date Issued: 2014

Fundamental movement skill proficiency status of girls aged 9-to-12 years from previously disadvantaged communities in Nelson Mandela Bay

  • Authors: Kahts, Samantha Andrea
  • Date: 2014
  • Subjects: Movement therapy for children -- South Africa -- Port Elizabeth , Exercise therapy -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:10107 , http://ndl.handle.net/10948/d1020060
  • Description: A lack of fundamental movement skill (FMS) proficiency in children can contribute to decreased physical activity (PA) levels, increased adiposity and poor acquisition of specialised sport specific movement skills. To prevent the latter, the identification of FMS status in early and middle childhood years is needed for targeted and specific interventions. Against the backdrop of physical education being omitted from the South African school curriculum, the presence of a patriarchal society, gender sporting stereotyping, high levels of unemployment and low education levels; the assessment of FMS status is particularly warranted. Aim of Study: The primary aim of this study was to assess the FMS proficiency of girls aged 9-to-12 years from previously disadvantaged communities within Nelson Mandela Bay. Methodology:A descriptive-exploratory-contextual study design, employing quantitative assessment techniques, was utilized. The sample comprised of 227 girls. Convenience sampling was employed. Testing consisted of FMS proficiency tests in the 20m and 40m sprint, standing long jump, throwing for distance, catching, static balance and throwing for accuracy. FMS process scores were assessed with the body component (BC) and Test of Gross Motor Development II (TGMD II) approaches. Anthropometric measurements of the standing and seated height, mass, arm span and leg length were additionally measured. Microsoft Excel® and Statistica® were used for descriptive and inferential statistical analysis. In the case of significant ANOVA results, the Scheffe post hoc test was used for pairwise comparisons. Statistical significance was set at p<.05 and practical significance (Cohen’s d) was set at d>.2. Pearson Correlation Coefficient identified statistical and practical correlations between two variables and chi square was applied to indicate differences in frequency distribution tables. Cramer’s V values were applied to determine practical significance in the case where statistical significant differences were identified between sets of frequency distributions.
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  • Date Issued: 2014

Fundamental movement skill proficiency status of girls aged 9-to-12 years from previously disadvantaged communities in Nelson Mandela Bay

  • Authors: Kahts, Samantha Andrea
  • Date: 2014
  • Subjects: Movement therapy for children -- South Africa -- Port Elizabeth , Exercise therapy -- South Africa -- Port Elizabeth , Kinesiology -- Social aspects -- South Africa -- Port Elizabeth
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: vital:10114 , http://hdl.handle.net/10948/d1021035
  • Description: Problem Statement A lack of fundamental movement skill (FMS) proficiency in children can contribute to decreased physical activity (PA) levels, increased adiposity and poor acquisition of specialised sport specific movement skills. To prevent the latter, the identification of FMS status in early and middle childhood years is needed for targeted and specific interventions. Against the backdrop of physical education being omitted from the South African school curriculum, the presence of a patriarchal society, gender sporting stereotyping, high levels of unemployment and low education levels; the assessment of FMS status is particularly warranted. Aim of Study The primary aim of this study was to assess the FMS proficiency of girls aged 9-to-12 years from previously disadvantaged communities within Nelson Mandela Bay. Methodology A descriptive-exploratory-contextual study design, employing quantitative assessment techniques, was utilized. The sample comprised of 227 girls. Convenience sampling was employed. Testing consisted of FMS proficiency tests in the 20m and 40m sprint, standing long jump, throwing for distance, catching, static balance and throwing for accuracy. FMS process scores were assessed with the body component (BC) and Test of Gross Motor Development II (TGMD II) approaches. Anthropometric measurements of the standing and seated height, mass, arm span and leg length were additionally measured. Microsoft Excel® and Statistica® were used for descriptive and inferential statistical analysis. In the case of significant ANOVA results, the Scheffe post hoc test was used for pairwise comparisons. Statistical significance was set at p<.05 and practical significance (Cohen’s d) was set at d>.2. Pearson Correlation Coefficient identified statistical and practical correlations between two variables and chi square was applied to indicate differences in frequency distribution tables. Cramer’s V values were applied to determine practical significance in the case where statistical significant differences were identified between sets of frequency distributions The BC approach indicated that most participants could not proficiently perform the run for speed (94.71 percent), standing long jump (96.9 percent) or throw for distance (83.56 percent). Only the catch was performed proficiently (91.19 percent). TGMD II results for the present study indicated that participants’ run for speed (100 percent) and catch (96.92 percent) were performed proficiently and their standing long jump (93.78 percent) and throw for distance (83.56 percent) process scores were performed least proficiently. Only the catch composite BC scores had a statistically (df=1.31; f=3.24; p=.024) and practically significant (d=0.82) improvement in the BC scores between the age groups 9 and 12 years. Only the standing long jump, throw for distance and throw for accuracy product scores improved statically and practically significantly with aging (p<.05; d>.2). Hence the further participants jumped, the faster they ran. Standing and seated height, weight and arm span improved statistically and practically significantly with age (p<.05; d>.2). All anthropometric variables, except for leg length, had a positive medium correlation (r=.335 to r=.439) with balance errors and this was only in 12 year olds. The throw for distance product scores had a medium correlation to seated height (r=.32) and arm span (r=.33). The run for speed had a medium correlation (r=.313) with mass. According to the IOTF classifications 24.67 percent of children were overweight and 7.49 percent of children were obese. Statistically significant differences were found for the run for speed (df=224; f=27.07; p=2.9E-11) and standing long jump (df=224; f=15.68; p=4.2E-07) when comparing product scores to normal weight, overweight and obese participants. These differences were furthermore found to be of medium to large practical significance between the normal and obese participants for the run for speed (d=0.61 to d=1.77) and Standing Long Jump (d=0.40 to d=1.33). On average 50 percent and 55 percent of participants partook 60 minutes or more of PA after school on week days and on weekend’s respectively. This PA consisted mostly of running and ball games. Only 10 percent of participants had commenced with menarche Conclusion Findings have highlighted the need for specifically targeted FMS interventions at an early age in female learners from previously disadvantaged communities. Both a product and process FMS assessment is warranted as this facilitates deductions about movement proficiency levels. A FMS proficiency assessment protocol is needed for South African children which is internationally comparable. Childhood overweight and obesity impacts FMS proficiency and should be addressed in future research. Cultural norms, gender stereotypes and sport management structures at primary school level seem to be affecting FMS proficiency and should be addressed in future research
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  • Date Issued: 2014

General structural and functional features of molecular chaperones:

  • Authors: Edkins, Adrienne L , Boshoff, Aileen
  • Date: 2014
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/164808 , vital:41174 , ISBN 978-94-007-7437-7 , DOI: 10.1007/978-94-007-7438-4_2
  • Description: Molecular chaperones are a group of structurally diverse and highly conserved ubiquitous proteins. They play crucial roles in facilitating the correct folding of proteins in vivo by preventing protein aggregation or facilitating the appropriate folding and assembly of proteins. Heat shock proteins form the major class of molecular chaperones that are responsible for protein folding events in the cell. This is achieved by ATP-dependent (folding machines) or ATP-independent mechanisms (holders). Heat shock proteins are induced by a variety of stresses, besides heat shock. The large and varied heat shock protein class is categorised into several subfamilies based on their sizes in kDa namely, small Hsps (HSPB), Hsp40 (DNAJ), Hsp60 (HSPD/E; Chaperonins), Hsp70 (HSPA), Hsp90 (HSPC), and Hsp100.
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  • Date Issued: 2014

Genesis of BIF-hosted hematite iron ore deposits in the central part of the Maremane anticline, Northern Cape Province, South Africa

  • Authors: Land, Jarred
  • Date: 2014
  • Subjects: Hematite -- South Africa -- Northern Cape , Anticlines -- South Africa -- Northern Cape , Geology, Stratigraphic -- Proterozoic , Hydrothermal deposits -- Northern Cape , Rare earth metals -- Northern Cape , Iron ores -- Geology -- Northern Cape , Transvaal Supergroup (South Africa)
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5095 , http://hdl.handle.net/10962/d1020905
  • Description: The Paleoproterozoic Transvaal Supergroup in the Northern Cape Province of South Africa is host to high-grade BIF-hosted hematite iron-ore deposits and is the country’s most important source of iron to date. Previous work has failed to provide a robust and all-inclusive genetic model for such deposits in the Transvaal Supergroup; in particular, the role of hydrothermal processes in ore-genesis has not been adequately clarified. Recent studies by the author have produced evidence for hydrothermal alteration in shales (Olifantshoek Supergroup) stratigraphically overlying the iron-ore intervals; this has highlighted the need to reassess current ore-forming models which place residual supergene processes at the core of oregenesis. This thesis focuses on providing new insights into the processes responsible for the genesis of hematite iron ores in the Maremane anticline through the use of newly available exploration drill-core material from the centre of the anticline. The study involved standard mineralogical investigations using transmitted/reflected light microscopy as well as instrumental techniques (XRD, EPMA); and the employment of traditional whole-rock geochemical analysis on samples collected from two boreholes drilled in the centre of the Maremane anticline, Northern Cape Province. Rare earth element analysis (via ICP-MS) and oxygen isotope data from hematite separates complement the whole-rock data. Iron-ore mineralisation examined in this thesis is typified by the dominance of Fe-oxide (as hematite), which reaches whole-rock abundances of up to 98 wt. % Fe₂O₃. Textural and whole-rock geochemical variations in the ores likely reflect a variable protolith, from BIF to Fe-bearing shale. A standard supergene model invoking immobility and residual enrichment of iron is called into question on the basis of the relative degrees of enrichment recorded in the ores with respect to other, traditionally immobile elements during chemical weathering, such as Al₂O₃ and TiO₂. Furthermore, the apparently conservative behaviour of REE in the Fe ore (i.e. low-grade and high-grade iron ore) further emphasises the variable protolith theory. Hydrothermally-induced ferruginisation is suggested to post-date the deposition of the post-Transvaal Olifantshoek shales, and is likely to be linked to a sub-surface transgressive hydrothermal event which indiscriminately transforms both shale and BIF into Fe-ore. A revised, hydrothermal model for the formation of BIF-hosted high-grade hematite iron ore deposits in the central part of the Maremane anticline is proposed, and some ideas of the author for further follow-up research are presented.
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  • Date Issued: 2014

Genesis of karst-hosted manganese ores of the Postmasburg Manganese Field, South Africa with emphasis on evidence for hydrothermal processes

  • Authors: Fairey, Brenton John
  • Date: 2014
  • Subjects: Karst -- South Africa -- Postmasburg , Manganese ores -- South Africa -- Postmasburg , Hydrothermal alteration -- South Africa -- Postmasburg , Manganese mines and mining -- South Africa -- Northern Cape , Petrology , Mineralogical chemistry , Geochemistry
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5094 , http://hdl.handle.net/10962/d1020904
  • Description: The Postmasburg Manganese Field (PMF), located in the Northern Cape Province of South Africa, once represented one of the largest sources of manganese ore worldwide. However, the discovery of the giant manganese deposits of the Kalahari Manganese Field (KMF) led to the gradual decline in manganese mining activity in the PMF. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes in ore formation and metasomatic alteration is not addressed. The identification of an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in the PMF ores studied in this thesis, is indicative of the influence of hydrothermal activity. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for the majority of samples analysed through bulk-rock techniques. The discovery of a Ba-Mn arsenate/vanadate similar to gamagarite may also indicate that the hydrothermal fluid affecting the ores was not only alkali-rich but also probably contained some As and V. The fluid was likely to be oxidized and alkaline in nature and is thought to have been a mature basinal brine. Various replacement textures, particularly of Na- and Krich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as oreminerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and the deviation of their character from the pigeon-hole-type classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. The discovery of hydrothermallydeposited alkali-rich assemblages in the PMF and KMF provides grounding for further investigation into a possible regional-scale hydrothermal event at least re-constituting the ores. Some shortcomings in previous works include disregard for the highly variable nature of the PMF deposits, the effects of hydrothermal activity of the ores and the existence of stratigraphic discrepancies. This study provides a single, broad model for the development of all manganese deposits of the PMF. The source of metals is attributed to all formations that stratigraphically overly the Reivilo Formation of the Campbellrand Subgroup (including the Reivilo Formation itself). The main process by which metals are accumulated is attributed to karstification of the dolomites. The interaction of oxidized, alkaline brines with the ores is considered and the overlying Asbestos Hills Subgroup BIF is suggested as a potential source of alkali metals.
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  • Date Issued: 2014

Genetic and biological characterisation of a novel South African Plutella xylostella granulovirus (PlxyGV) isolate

  • Authors: Abdulkadir, Fatima
  • Date: 2014
  • Subjects: Diamondback moth , Diamondback moth -- Control -- South Africa , Plutellidae -- Control -- South Africa , Baculoviruses , Cruciferae -- Diseases and pests -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4113 , http://hdl.handle.net/10962/d1013059
  • Description: The diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), is an important pest of cruciferous crops worldwide. The prolonged use of synthetic chemical insecticides as a primary means of control has resulted in the development of resistance in pest populations. In addition, the pest has also evolved resistance to the bacterial insecticidal protein of Bacillus thuringiensis which is also widely used as a method of control. Baculoviruses are considered as effective alternatives to conventional methods of control when incorporated into integrated pest management (IPM) programmes. These viruses target the larval stages of insects, are generally host-specific and are safe for use in the environment. This study aimed to isolate a baculovirus from a laboratory-reared P. xylostella colony, characterise it genetically and then evaluate its virulence against neonate and fourth instar larvae. A laboratory colony of P. xylostella was established using pupae and asymptomatic larvae collected from a cabbage plantation outside Grahamstown in the Eastern Cape province of South Africa. The colony flourished in the laboratory due to prime conditions and availability of food. The duration of development from egg to adult was determined by observation and imaging of the various life stages. The mean developmental time from egg to adult was observed to be 14.59 ± 0.21 days. The population of the insects increased rapidly in number leading to overcrowding of the insect colony, and hence appearance of larvae with viral symptoms. Occlusion bodies (OBs) were extracted from symptomatic larval cadavers and purified by glycerol gradient centrifugation. Analysis of the purified OBs by transmission electron microscopy revealed the presence of a granulovirus which was named PlxyGV-SA. The virus isolate was genetically characterised by restriction endonuclease analysis of the genomic DNA, and PCR amplification and sequencing of selected viral genes. The complete genome sequence of a Japanese P. xylostella granulovirus isolate, PlxyGV-Japan, has been deposited on the GenBank database providing a reference strain for comparison with DNA profiles and selected gene sequences of PlxyGV-SA. BLAST analysis of the granulin gene confirmed the isolation of a novel South African PlxyGV isolate. Comparison of the restriction profiles of PlxyGV-SA with profiles of PlxyGV-Japan and other documented PlxyGV profiles obtained by agarose gel electrophoresis revealed that PlxyGV-SA is a genetically distinct isolate. The data obtained from the sequencing and alignment of ecdysteroid UDP-glucosyltransferase (egt), late expression factor 8 (lef-8) and late expression factor 9 (lef-9) genes with those of PlxyGV-Japan also showed that PlxyGV-SA is a genetically different isolate. In order to determine the biological activity of PlxyGV-SA against neonate and fourth instar P. xylostella larvae, surface dose bioassays were conducted. The median lethal concentration of the virus required to kill 50% (LC₅₀) and 90% (LC₉₀) of the larvae was estimated by feeding insects with a range of doses. In addition, the time to kill 50% of the larvae (LT₅₀) was determined by feeding insects with the LC₉₀ concentration. Larval mortality was monitored daily until pupation. The data obtained from the dose response assays were subjected to probit analysis using Proban statistical software. The time response was determined using GraphPad Prism software (version 6.0). The LC₅₀ and LC₉₀ values for the neonate larvae were 3.56 × 10⁵ and 1.14 × 10⁷ OBs/ml respectively. The LT₅₀ was determined to be 104 hours. The neonate larvae were found to be more susceptible to infection than the fourth instar larvae with the same virus concentration. The concentrations used for the neonate larvae assay did not have a significant effect on the fourth instar as no mortality was recorded. This is the first study to describe a novel South African PlxyGV isolate and the results suggest that PlxyGV-SA has significant potential for development as an effective biopesticide for the control of P. xylostella in the field.
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  • Date Issued: 2014

Genetic and morphometric variation of Octopus vulgaris in the Benguela Current region

  • Authors: De Beer, Chénelle Lesley
  • Date: 2014
  • Subjects: Common octopus -- Africa, Southern , Common octopus -- Genetics , Common octopus -- Morphology , Common octopus -- Geographical distribution , Variation (Biology) , Benguela Current
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5362 , http://hdl.handle.net/10962/d1012971
  • Description: The Benguela Current is a cold eastern boundary current located on the south-western coast of the African continent. The establishment of its present day features approximately two million years ago has triggered allopatric events which have driven genetic and/or phenotypic differentiation in many of the warm-temperate organisms that previously had continuous distributions along the south and west coast of southern Africa. However, since many of these species have responded differently, despite similar isolation times, research in this region provides a unique opportunity to increase our understanding of evolutionary processes. The common octopus (Octopus vulgaris, Cuvier 1797) is a coastal, sedentary species, inhabiting coral reefs or rocky environments at depths of up to a 100m. It is considered to be one of the most extensively studied cephalopod species due to its worldwide distribution. However, very little research has been conducted on O. vulgaris in southern Africa. In order to gain a holistic understanding of the effects of the Benguela Current on population connectivity, genetic and phenotypic diversity, and evolutionary history of O. vulgaris, a comparative genetic and morphological study was conducted across the Benguela region. A total of 168 specimens of O. vulgaris were collected from four different regions across the Benguela system. A small tissue sample was preserved in ethanol for molecular analysis, and the specimen was frozen whole for morphometric analysis in the laboratory. Octopus vulgaris genetic population structure and evolutionary history was investigated using a 580bp fragment of the mitochondrial cytochrome b (cytb) gene for 76 individuals located within the Benguela region, yielding 10 different haplotypes. AMOVA and pairwise FST analyses revealed significant genetic differentiation suggesting a northern-southern Benguela divergence. Estimates of time since most recent common ancestor, based on biogeographical calibrators and coalescent analyses, indicated that isolation between the Angolan and South African population occurred between ~231 Ka and 1 Ma. Mismatch distribution analyses revealed a past population expansion within the South African O. vulgaris roughly 129.31 Ka, whilst Bayesian skyline plots were indicative of gradual demographic growth within the Angolan population in the last ~100 Ka. Observed O. vulgaris population structure and demographic history was likely the result of historical climate-induced change within the system. Reconstruction of phylogenetic relationships within the Octopus genus, using cytb and COI suggest that O. vulgaris is not a monophyletic group and a major systematic revision is required. Furthermore, unidentified individuals from South Africa were found to group with species from Indo-West Pacific Oceans and were therefore considered to have been translocated through ballast water from Asia. While the molecular analysis indicated a significant northern-southern Benguela structure results from the principle component analysis (PCA) and discriminate function analysis (DFA) were unable to distinguish between O. vulgaris from different sampling localities throughout the Benguela Current region based on soft-parts, hard-parts and meristic characters. The lack of phenotypic variation, despite significant genetic divergence, highlights the importance of multi-method approaches in gaining a holistic understanding of the taxonomy and biogeography of species.
  • Full Text:
  • Date Issued: 2014

Genetic and phenotypic characterisation of foodborne bacteria isolated from ready-to-eat foods in Alice, South Africa

  • Authors: Nyenje, Mirriam E
  • Date: 2014
  • Subjects: Foodborne diseases -- Microbiology , Pathogenic bacteria
  • Language: English
  • Type: Thesis , Masters , MSc (Microbiology)
  • Identifier: vital:11279 , http://hdl.handle.net/10353/d1016109 , Foodborne diseases -- Microbiology , Pathogenic bacteria
  • Description: Foodborne illnesses following the ingestion of contaminated food are a major public health problem worldwide. They include a broad group of illnesses ranging from mild to chronic or life-threatening; caused by either toxins released from the disease-causing microbes, or by the microbes themselves. Antimicrobial susceptibility data shows an alarming increase in the frequency of antimicrobial resistance of foodborne pathogens, a situation which is worrisome as it decreases the effectiveness of drugs employed to reduce the morbidity and mortality associated with serious and life-threatening infections and thus, compromising human health. This study was therefore designed to assess the occurrence and characterization of bacterial foodborne pathogens in various foods sold in Alice, Eastern Cape Province of South Africa in an effort to throw more light on the inherent risk associated with such foods. The study was conducted during the period of 2011 - 2013. Two university restaurants and eight ready-to-eat food vending sites in Alice Town were selected based on their prominence to the students, workers and rest of the community. Microbiological analysis was conducted on 252 samples which included vegetables, potatoes, rice, pies, beef and chicken stew. The isolates were identified using biochemical tests and confirmation of the two most prevalent organisms (Listeria ivanovii and Enterobacter cloacae) was done using PCR techniques. The antimicrobial susceptibility profile of Listeria ivanovii and Enterobacter cloacae strains were identified using the disc diffusion technique; minimum inhibitory concentration was determined by the broth dilution method and M.I.C. Evaluator test strips. The microtiter plate adherence assay was employed to ascertain the ability of these isolates to adhere to a surface whereas the role of cell surface properties in biofilm formation was assessed using the coaggregation and autoaggregation assays. The architecture of the formed biofilms was examined under the scanning electron microscope. The virulence and resistant genes were also detected and characterised by sequencing the PCR products. Bacterial growth was present in all the food types tested; organisms isolated included: Listeria spp. (22%), Enterobacter spp. (18%), Aeromonas hydrophila (12%), Klebsiella oxytoca (8%), Proteus mirabilis (6.3%), Staphylococcus aureus (3.2%) and Pseudomonas luteola (2.4%). PCR confirmed 30 (97%) isolates as E. cloacae complex while 44% (22/50) tested positive for L. ivanovii. All the strains of E. cloacae (100%) and 96% of L. ivanovii isolates (based on phenotypic identification) were resistant to at least four or more of the antibiotics. In this study, bla-TEM was also detected from 48 (96%) of L. ivanovii and 30 (100%) of E. cloacae strains; further analysis of the bla-TEM demonstrated the occurrence of bla-TEM-1. Of the 56 bla-TEM-1 positive isolates sequenced, 7% (4/56) had mutation of either insertion or substitution of a nucleotide. Two virulence genes (ucaA and hlyA) were detected in E. cloacae isolates and none in L. ivanovii using PCR. Sequence analysis of the hsp60 gene reported the presence of two sub-species for E. cloacae; E. cloacae cluster III (75%) and E. cloacae cluster IV (25%); while analysis of the iap60 gene demonstrated that 55.8% (19/34) were L. ivanovii, 44% (15/34) L. seeligeri and 14.7% (5/34) L. welshemeri. A total of 90% L. ivanovii and 88% E. cloacae strains demonstrated the ability to form biofilms; the coaggregation index ranged from 12 to 77% while the autoaggregation index varied from 11 to 55% for L. ivanovii and 27% to 98% for E. cloacae. The findings of this study indicate that most of the ready-to-eat food samples examined did not meet bacteriological quality standards, thus posing potential risks to consumers. This should draw the attention of the relevant authorities to certify that hygienic standards are improved to curtain foodborne infections. Furthermore, the presence of multi-resistant strains is of major concern as these foods could serve as important vehicles transmitting multi-resistant bacteria and genes to humans. In addition the ability of these pathogens to form biofilms may lead to adherence of these organisms to kitchen utensils and other environments leading to cross-contamination of food processed in these areas and increase resistance of organisms to antimicrobial agents.
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  • Date Issued: 2014

Genetic diversity and population structure of plasmodium falciparum from four epidemiological locations in Malawi

  • Authors: Selemani, George Paul
  • Date: 2014
  • Subjects: Plasmodium falciparum , Parasites -- Molecular genetics , Infection -- Genetic aspects , Disease susceptibility -- Genetic aspects
  • Language: English
  • Type: Thesis , Masters , MTech
  • Identifier: vital:10359 , http://hdl.handle.net/10948/d1021026
  • Description: In malaria-endemic regions, Plasmodium falciparum (P. falciparum) infection is characterized by extensive genetic/antigenic diversity. Describing this diversity provides important information about the local molecular epidemiology of infecting P. falciparum parasites. Intriguingly, one of the major obstacles to the development of an effective malaria vaccine has been the genetic polymorphisms exhibited by P. falciparum genes encoding targets of human immune system. This situation has necessitated the development of polyvalent vaccines with wide antigenic coverage that would increase the likelihood of vaccine efficacy that covers wide geographical areas of malaria endemic countries. Limited reports are available on the population genetic diversity and structure of P. falciparum in Malawi, and this is of particular concern as the country has put in place several interventions to combat the disease. The primary aim of the research project was to determine the genetic diversity and population structure of P. falciparum isolates and comparing complexity from four different epidemiological settings in Malawi using msp-2 gene polymorphisms. Samples were collected from four epidemiological locations in the north, centre and southern regions of Malawi. The diversity and genetic differentiation of P. falciparum populations were analyzed based on the highly polymorphic block 3 msp-2 gene. One hundred and twenty patient samples who presented with signs and symptoms of malaria and who had microscopically confirmed P. falciparum infection were enrolled in the study after they had satisfied the inclusion criteria. Parasite DNA was extracted from the blood spot on to filter paper and analyzed by genotyping the msp-2 gene using allele-specific nested PCR. A total of 28 msp-2 block 3 fragments, defined by the size and the allelic types were detected in the 102 patients. The length variants of the PCR product ranged from 240basepairs (bp) to 450bp for the K1/FC and 410bp to 780bp for the 3D7/IC allelic families. Isolates of the 3D7 alleles were predominant in the population (59 percent), compared to isolates of the K1/ FC27 alleles (41 percent) and for 3D7 and K1 most of the isolates were monoclonal infections. In comparisons between the sites, we observed the highest prevalence of mixed infection in Mwanza (46.7 percent) followed by Dwangwa (23.3 percent) compared to Bolero (16.7 percent) and Mitundu (16.7 percent). The difference in prevalence of mixed infections between Mwanza and the other sites was statistically significant (p=0.041). There was also a non-significant trend towards a higher mean genotype number per isolate in the children aged >5 years compared to those below 5 years of age. These data suggest differences in prevalence rates of mixed infections in different geographical/epidemiological settings in Malawi. Further studies are needed to confirm, with larger sample sizes, the observation of a non-significant trend towards higher multiclonality of infection in older children in malaria endemic areas of Malawi.
  • Full Text:
  • Date Issued: 2014

Geographical variation in effects of nutrient levels and grazing intensity on community structure between upwelling and non-upwelling regions of South Africa

  • Authors: Steele, Nikita
  • Date: 2014
  • Subjects: Upwelling (Oceanography) , Upwelling (Oceanography) -- Indian Ocean , Algae -- Indian Ocean , Algae -- Effect of grazing on -- Indian Ocean
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5873 , http://hdl.handle.net/10962/d1013013
  • Description: The aim of this thesis was to assess the influence of upwelling on alga-grazer interactions in rocky shore communities along the south coast of South Africa using grazer exclusion treatments with controls and procedural controls set out in a block design and monitored for algal cover roughly monthly for one year. In the first experiment grazers were excluded from treatment plots at two upwelling and two non-upwelling sites and the rates of algal biomass accumulation were then compared. The upwelling sites showed significantly faster algal colonisation rates, with Ulva rigida being the first species to colonise the rocks. Final algal cover and biomass did not differ significantly between upwelling and non-upwelling sites in control plots open to grazers, but were significantly higher in grazer exclusion plots at upwelling sites indicating stronger grazing effects. This was confirmed by estimating the intensity of grazing using the log-response ratio (LRR), which was calculated from treatment and control plots. Upwelling sites had significantly lower LLR values indicating stronger grazing effects, than at non-upwelling sites, despite no difference in grazer abundances. The second experiment examined the effects of nutrient addition on algal growth and community composition by comparing high nutrient enrichment plots with low enrichment plots at one upwelling and one non-upwelling site. ANOVA indicated faster growth rates and significantly higher final algal biomass in high enrichment plots compared to low enrichment and control plots at both upwelling and non-upwelling sites. A two-way ANOVA indicated significantly higher algal cover in high enrichment plots compared to the data from the grazer exclusion plots in experiment 1 at both sites, suggesting that nutrient addition plays a major role in algal growth and community composition. The findings of these studies have shown significant differences between treatments, sites and seasons, with significant differences not only occurring in algal cover but also accumulation of algal biomass and recruitment patterns between treatments. The small scale local processes acting within a few centimetres (plots) or tens of meters (among blocks) can also be reflected over larger scales such as sites (upwelling/non-upwelling shores). Further, these studies have demonstrated that various factors such as the effects from increased nutrients at upwelling cells and the change in grazing effects due to enhanced nutrients can determine the abundance and diversity of the community structure, including an increase in the abundance of the fast growing algae Ulva rigida, and a slow recovery of the brown and red algae.
  • Full Text:
  • Date Issued: 2014

Geomorphic origin and dynamics of deep, peat-filled, valley bottom wetlands dominated by palmiet (Prionium serratum) : a case study based on the Goukou Wetland, Western Cape

  • Authors: Job, Nancy Merle
  • Date: 2014
  • Subjects: Wetlands -- South Africa -- Western Cape , Peatlands -- South Africa -- Western Cape , Peatland conservation -- South Africa -- Western Cape , Peatland management -- South Africa , Aquatic plants -- South Africa -- Western Cape , Geomorphology -- South Africa -- Western Cape
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:4782 , http://hdl.handle.net/10962/d1013122
  • Description: The Goukou Wetland is a 700 ha unchannelled valley bottom wetland near the town of Riversdale in the Western Cape of South Africa. The wetland is approximately 16 km long and between 200 and 800 m wide, with peat deposits up to 8 m deep that get progressively shallower downstream. The Goukou Wetland is one of the last remaining intact peatlands of significant size in the Western Cape. However, there is increasing human pressure on these peat wetlands, where the dominant plant is palmiet (Prionium serratum), which is endemic to the Western and Eastern Cape Provinces of South Africa. Palmiet is viewed as a problem plant by farmers as it is believed to block waterways and promote inundation of arable land and infrastructure. Many landowners therefore actively remove palmiet from peatlands, threatening the integrity of these wetlands. Although the hydrogeomorphic origin of large, non-peat floodplain and valley bottom wetlands has been investigated in South Africa, unchannelled valley-bottom wetlands with deep peat accumulations are rare features and have not been well studied. The hydrogeomorphic factors leading to peat accumulation have been documented elsewhere in Southern Africa, where aggradation due to sedimentation along trunk streams may block a tributary stream, elevating the local base level of the tributary, creating the accommodation space for organic sedimentation. Alternatively, sedimentation along a trunk stream at the toe of a tributary stream may similarly block a trunk stream, promoting organic sedimentation along the trunk stream upstream of the tributary. This pattern of peat accumulation is associated with declining peat thickness upstream of the blocked valley. In the case of the Goukou Wetland, however, peat depth and organic content was found to increase consistently upstream from the toe to the head of the wetland. The Goukou Wetland was graded along its length, with gradient increasing consistently upstream in response to longitudinal variation in discharge. There was no clear relationship between peat formation and tributary streams blocking the wetland. Instead, the distribution of peat and the extent of the wetland appeared to be controlled by the plant palmiet, whose clonal nature and robust root, rhizome and stem system allowed it to grow from channel banks and islands into fast-flowing river channels, slowing river flows and ultimately blocking the channel. The promotion of diffuse flows within the dense, monospecific stands of palmiet creates conditions conducive to water retention and peat accumulation. By growing across the full width of the valley floor, the plant is able to constrict the stream, trapping sediment and slowing flows such that the fluvial environment is changed from a fast flowing stream to one with slow, diffuse flow. These processes appear to lead to the formation of organic sediment, accumulating to form a deep peat basin. The sustained input of water from the folded and fractured quartzite lithologies of the Cape Supergroup that make up the Langeberg Mountains, which provide the bulk of the water supply to the wetland, is also important in promoting permanent flooding in the wetland. A feature that characterized the wetland was the fact that bedrock across the valley beneath the peat deposits exhibited a remarkably uniform elevation. This suggests that over long periods of time (tens to hundreds of thousands of years), bedrock has been laterally planed across the valley floor. It is proposed that valley widening associated with lateral planning of Uitenhage Formation rocks has taken place during periods of episodic very high flows. During these episodes, erosion cuts into the peat wetland and valley sides, cutting to bedrock and planing the valley floor to a uniform elevation for a given distance from the head of the wetland. Periods of episodic degradation are followed by periods of renewed peat accumulation associated with palmiet establishment, such that the wetland valley is shaped by repeated cycles of cutting and filling. Palmiet can be considered an “ecosystem engineer” that is integral to the formation of these deep peat basins. Removal of palmiet from these systems is likely to have negative consequences for the wetland and its functions in that water storage will be reduced, erosion will increase dramatically, and the water-purification function of the wetlands will be lost. Management of these wetlands, which are close to the geomorphic threshold slopes for their size, is therefore essential if they are to be preserved for the benefit of human well-being.
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  • Date Issued: 2014

GIS and remote sensing as a potential tool to support digital soil mapping in the Eastern Cape province in South Africa

  • Authors: Mathe, Tumelo
  • Date: 2014
  • Language: English
  • Type: Thesis , Masters , MSc (Geographic Information System)
  • Identifier: vital:11533 , http://hdl.handle.net/10353/d1019858
  • Description: This study is based on assessing the potential use of GIS and Remote Sensing in trying to fill the various soil maps of selected regions at different scales with spatial soil data. A variety of processes are available for use. These include band ratios, principal component analysis as well as use of a digital elevation model (DEM). With the advent of GIS and Remote Sensing, these principles in the new niche of study are investigated to check if they can be used to augment the current processes available in soil mapping techniques. Such processes as band ratioing, principal component analysis and use of Digital Elevation Models (DEMs) are investigated to check if they can be used in soil mapping techniques. From the results produced it is evident that these processes have the potential to be used in the Digital Soil Mapping process. Despite the limitation of remote sensing to a few centimetres of the topsoil these processes can be used together with the soil mapping techniques currently being used to come up with soil maps.
  • Full Text:
  • Date Issued: 2014

Gold mineralisation at Masumbi Au-Cu Prospect, west Kenya : implication for gold exploration in the Archaean Ndori Greenstone Belt of Kenya

  • Authors: Salimo, Luckmore
  • Date: 2014
  • Subjects: Gold mines and mining -- Kenya -- Nyanza Province , Copper -- Kenya -- Nyanza Province , Prospecting -- Kenya -- Nyanza Province , Chalcopyrite -- Kenya -- Nyanza Province , Metamorphism (Geology) , Geochemistry
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: vital:5096 , http://hdl.handle.net/10962/d1020961
  • Description: The Masumbi Au-Cu deposit in the Ndori Greenstone Belt of western Kenya is hosted in dacitic volcanics of the Nyanzian Group (2710 ± 340 Ma) and dioritic to granodioritic felsic intrusives (2504 ± 48 Ma). The deposit is characterised by gold and copper mineralisation that is associated with quartz-sulphide veins and veinlets. The copper mineralisation typically occurs as chalcopyrite. Gold is closely associated with pyrite in mineralogy and its pathfinder elements silver, bismuth, tellurium and selenium in geochemistry. The gold occurs in two forms that may indicate two generations of precipitation: the equant and the elongate forms. Based on Au/Ag ratios, the equant gold grains can be classified as native gold as their gold content is greater than 90 wt%. The elongate gold grains can be classified as electrums as their silver content is greater than 38 wt%. While there is a strong Au-Ag association within individual gold grains supporting an orogenic model for the gold mineralisation, mineralisation at the Masumbi Prospect appears atypical of Archaean orogenic gold deposits because of the abundance of copper (up to 0.43%). The enrichment of silver, copper, bismuth and tellurium in ore assemblages is common in porphyry, VMS and epithermal systems, but their presence at Masumbi does not preclude the formation as an orogenic deposit. Assay results from three Masumbi diamond drill-holes show an apparent correlation between gold and copper. However, petrography and electron probe microanalyses results from this study indicate that chalcopyrite is an earlier phase than pyrite as it occasionally occurs as inclusions in pyrite. This petrogenetic relationship between pyrite and chalcopyrite suggests that there is no temporal relationship between gold and copper mineralisation. Statistical analysis of the assays shows no linear correlation between gold and copper thereby supporting the above findings. The gold and copper mineralisation have been interpreted as forming as two separate events with copper forming first followed by gold. These events are both related to the intrusion of the felsic rocks that are associated with the Aruan metamorphic event that has been responsible for the bulk of the gold mineralisation on the Tanzanian Craton. The common alteration assemblage in the Masumbi rocks comprises chlorite and epidote. This alteration assemblage is typical of regional greenschist metamorphic facies grading into amphibolite metamorphic facies in the Nyanzian Group of Kenya. However, these alteration minerals could possibly be products of propylitic alteration in the rock groundmass. Other alteration mineral assemblages, possibly of hydrothermal origin, comprise muscovite, sericite, quartz, carbonate, associated with the sulphides pyrite and chalcopyrite. Although the occurrence of gold appears to be controlled by the presence of pyrite, it is also associated with silicification. Exploration methods have been proposed to target undiscovered gold deposits in the Ndori Greenstone Belt that are similar to the Masumbi deposit. These methods could probably be applied to vein-type gold deposits in other granite-greenstone terranes in the Lake Victoria Goldfields.
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  • Date Issued: 2014

Gold mineralization in a high grade metamorphic terrane in the Handeni District, Eastern Tanzania

  • Authors: Bitesigirwe, Godfrey Stephen
  • Date: 2014
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/54756 , vital:26609
  • Description: Most orogenic type gold deposits are formed under low greenschist facies to mid amphibolite facies metamorphic conditions and deposition is either structurally or lithologically controlled. A few known gold deposits found in high grade metamorphic terranes include those in the Yilgarn craton in Australia, Renco in Zimbabwe, Hemlo in Canada and the recently discovered Handeni deposit in Tanzania. Within Tanzania, gold deposits are mainly hosted in Archaean low grade metamorphic rocks commonly known as the Lake Victoria greenstone belt. The greenstone belts of Tanzania are of Nyanzian age (> 2.5Ga) and are located to the south and east of Lake Victoria on the Tanzania craton. The Tanzania Craton is surrounded by Usagaran 1.9 Ga rocks (the east African orogenic belt (EAO) better known as the Mozambique belt) to the east and the Ubendian belt to the south and west. Published reports show that the eastern part of the Tanzania Craton is dominated by the fragments of Archaean rocks. Metamorphism along East Africa and the Tanzania Craton is due to several geological events. These geological events include the intrusion of granites in the Archaean Tanzania Craton (3 Ga), subduction of ocean plate resulted to the formation of Usagaran belt (1.9 Ga), opening and closure of Mozambique Ocean, which resulted in the formation of the Mozambique belt between 700 – 800 Ma and the Pan African orogeny at 640 – 620 Ma, which is associated with the formation of Gondwana. It is believed that fragments from the Archaean Tanzania craton were re - metamorphosed during these events. The Handeni project (the focus of this thesis) is located in the northern portion of the eastern part of the Usagaran belt (1.9 Ga) comprising the eastern part of Archaean Tanzania Craton. The area is characterized by Proterozic rocks of basaltic composition. The documented 2.7 Ga rocks at the Kilindi Handeni Superterrane at the northern part of the Usagaran belt correlate well with 2.7 Ga of Nyanzian rocks of Archaean Tanzania craton. The Handeni project area is geologically dominated by metamorphosed and deformed units of quartzofeldspathic gneisses, migmatitic gneiss, garnet silicified rock, garnetiferous amphibolite, garnetiferous granulite, graphitic schist and hornblende pyroxenite. Intensive deformation features that were developed include folds (sheath folds, micro and macro scales), faults, shears and regional thrusts. This thesis focuses on identifying the protolith of the rocks, alteration minerals, and metamorphic assemblages in the project area in order to understand the timing of gold mineralization. Geological investigation of core, ore petrology and mineralogy, mineral composition by using JEOL microprobe analysis and XRF analysis of bulk rocks were utilized. All the analytical work was done at the Geology laboratory, Rhodes University. Petrographic analysis shows that the rocks sampled in the study area are characterized by alteration minerals such as calcite, dolomite and sericite. Sulphide minerals including chalcopyrite, pyrrhotite, pyrite, pentlandite and gersdorffite were identified. Gold mineralization is associated with disseminated sulphides in association with trace amounts of base metals. Four rock types were proposed as host rocks for the mineralization, namely garnet silicified rock with superimposed quartz veins, garnetiferous amphibolite, garnetiferous granulite and hornblende pyroxenite. Fold troughs, filled fractures associated with episodes of folding, quartz veins and shear zones are suggested as gold precipitation sites. The presence of high grade metamorphic rocks containing gold, intermediate to low grade assemblages with sulphides and associated hydrothermal alteration as well as a complex deformation history suggests that the Handeni mineralization took place over an extended time period stretching from a ductile to a brittle environment.
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  • Date Issued: 2014

Good's casualty for time series: a regime-switching framework

  • Authors: Mlambo, Farai Fredric
  • Date: 2014
  • Subjects: Time-series analysis , Econometrics
  • Language: English
  • Type: Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10948/6018 , vital:21025
  • Description: Causal analysis is a significant role-playing field in the applied sciences such as statistics, econometrics, and technometrics. Particularly, probability-raising models have warranted significant research interest. Most of the discussions in this area are philosophical in nature. Contemporarily, the econometric causality theory, developed by C.J.W. Granger, is popular in practical, time series causal applications. While this type of causality technique has many strong features, it has serious limitations. The processes studied, in particular, should be stationary and causal relationships are restricted to be linear. However, we cannot classify regime-switching processes as linear and stationary. I.J. Good proposed a probabilistic, event-type explication of causality that circumvents some of the limitations of Granger’s methodology. This work uses the probability raising causality ideology, as postulated by Good, to propose some causal analysis methodology applicable in a stochastic, non-stationary domain. There is a proposal made for a Good’s causality test, by transforming the originally specified probabilistic causality theory from random events to a stochastic, regime-switching framework. The researcher performed methodological validation via causality simulations for a Markov, regime-switching model. The proposed test can be used to detect whether none stochastic process is causal to the observed behaviour of another, probabilistically. In particular, the regime-switch causality explication proposed herein is pivotal to the results articulated. This research also examines the power of the proposed test by using simulations, and outlines some steps that one may take in using the test in a practical setting.
  • Full Text:
  • Date Issued: 2014

Good-Gooder-Goodest

  • Authors: Majola, Fundile Lawrence
  • Date: 2014
  • Subjects: South African fiction (English) -- 21st century , Xhosa fiction -- 21st century , Short stories, South African -- 21st century , Short stories, Xhosa -- 21st century , Creative writing (Higher education) -- Research -- South Africa , Creative writing -- Fiction , South African fiction -- Study and teaching (Higher)
  • Language: English , Xhosa
  • Type: Thesis , Masters , MA
  • Identifier: vital:5982 , http://hdl.handle.net/10962/d1015657
  • Description: My stories are set in the townships, and move with the vigorous rhythms and jagged structures of township life. Some of them are written in English and others in isiXhosa. Some of the dialogue is township slang, a mixture of languages; and pure isiXhosa. The stories follow no particular pattern and are arranged according to any form of chronology, and different voices, at times as a man/boy and in others as a girl. The characters are not related each story perfectly stands for itself. Some of the stories hark back to the days of apartheid and are seen through the eyes of a child confused by the humiliations of his elders. , Amabali am asekelwe ezilokishini yaye ahambelana neemeko ezimaxongo zokuphila zasezilokishini apho yaye amanye asukela kwixesha lengcinezelo yesizwe esimnyama. Imiba echatshazelwa kula mabali iquka intlupheko, intiyo kwakunye nokuphilisana koluntu ezilokishini, phantsi kwezo meko. Amabali la ndizame ukuwenza alandele indlela yokubalisa yhenkwenkwana enguSkhumba, ethi ibone iqwalasele iimeko zokuphila zabantu bohlanga lwayo. Ingqokelela esisiqendu sokuqala yona ibhalwe ze yangeniswa ngesiNgesi. , This thesis is presented in two parts: English and isiXhosa.
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  • Date Issued: 2014

Grade 3 teachers’ strategies to help English second language learners overcome interlingual spelling errors

  • Authors: Rululu, Nomfusi Gladys
  • Date: 2014
  • Subjects: Interlingual -- Spelling errors , Teacher`s strategies -- Grade 3
  • Language: English
  • Type: Thesis , Masters , M Ed
  • Identifier: http://hdl.handle.net/10353/1349 , vital:26548 , Interlingual -- Spelling errors , Teacher`s strategies -- Grade 3
  • Description: Spelling is one of the most important components of writing at single-word level and is regarded as a vital part of written communication. Also spelling is seen as an important tool in writing. Without the ability to spell as a broader aspect of writing, a person could not be called literate in the conventional sense of the word. Although the spelling is so important, learners in the foundation phase especially in grade three commit interlingual spelling errors. This means that at this stage learners transfer patterns of the mother tongue to the second language. By so doing that they write English words as the way they are pronounced in their mother tongue. Hence this study investigated grade three teachers’ strategies to help English second language learners overcome interlingual spelling errors. In exploring these strategies this study adopted a qualitative approach in order to ensure reliability and validity of the study. The data gathering instruments used included semi-structured interviews, classroom observations and document analysis. One primary school in Mdantsane a township in East London District was purposively selected to form the context of the study. The medium of instruction in this school is isiXhosa in the foundation phase and English is taught as a subject. Two teachers and their classes participated in this study. The findings of the study revealed that different factors contribute to interlingual spelling errors. These factors are status of the parent (they were illiterate), pronunciation, language borrowing and language transfer. It is also revealed that teachers have a limited number of strategies to teach learners overcome interlingual spelling errors instead they use strategies to teach spelling generally.
  • Full Text:
  • Date Issued: 2014
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