Immobilisation of an Aspergillus niger derived endo-1,4-β-mannanase, Man26A, for the production of prebiotic mannooligosaccharides from soybean meal
- Authors: Anderson, Amy Sage
- Date: 2024-10-11
- Subjects: Aspergillus niger , Soybean meal , Mannosidases , Oligosaccharides , Immobilized microorganisms
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/463897 , vital:76455
- Description: This study investigated the potential for antibiotic alternatives in the form of prebiotics produced from the enzymatic breakdown of soybean meal (SBM). This study first investigated the immobilisation of an endo-1,4-β-mannanase derived from Aspergillus niger on glutaraldehyde-activated chitosan nanoparticles (CTS) and glutaraldehyde-activated chitosan-coated magnetic Fe3O4 nanoparticles (MAGS-CTS) - which could be effectively used to hydrolyse the galactomannan contained in SBM in a recyclable manner. The mannooligosaccharides (MOS) produced from the enzymatic digestion of SBM were then analysed for their prebiotic and antimicrobial capabilities to determine whether the strategy employed was capable of promoting and inhibiting probiotic and pathogenic growth, respectively. An Aspergillus niger endo-1,4-β-mannanase, Man26A, was confirmed by FTIR (Fourier-transform infrared spectroscopy) and XRD (X-ray powder diffraction) to be immobilised onto CTS and MAGS-CTS by covalent bonding. The immobilisation (%) and activity yields (%) were 81.14% and 35.45%, and 55.75% and 21.17%, respectively. The biochemical properties (pH and temperature optima, and temperature stability) of both the free CTS and MAGS-CTS immobilised Man26A enzymes were evaluated, with the pH optima shifting to a lower pH range after immobilisation (pH 2.0 – 3.0 vs. 5.0), while the temperature optima and stabilities remaining unchanged (at 60°C). CTS and free enzymes exhibited identical thermal stabilities, maintaining 100% activity for the first 6 hours at 55°C, while MAGS-CTS showed an immediate drop in relative activity after the first 30 minutes of incubation. Recyclability analysis revealed that CTS could be effectively reused for six reaction cycles, while the MAGS-CTS immobilised enzyme could only be used once. Both enzymes could be efficiently stored at 4ºC, showing a relative residual activity of 73% after 120 hours of storage. Substrate kinetic analysis showed that the free enzyme had the highest catalytic capabilities in hydrolysing locust bean gum (LBG), with the CTS immobilised enzyme was the most efficient in hydrolysing SBM, the insoluble, complex substrate. Sugar residues produced from the hydrolysis of LBG illustrated the effective breakdown of galactomannan to mannobiose (M2), mannotriose (M3), mannotetrose (M4), and mannohexose (M6). SBM-produced sugars analysed via TLC and HPLC indicated that the MOS residues were most probably glucose, galactose, and galactomannans (GM2 and GM3). The SBM-produced sugars were then evaluated for their prebiotic effect, illustrating their successful utilisation as a carbon source by probiotic bacteria; Streptococcus thermophilus, Bacillus subtilis and Lactobacillus bulgaricus. Evaluation of the antimicrobial activities of the SBM-produced sugars digested by probiotics suggested that their metabolites had the potential to be used as an antibiotic alternative. This study therefore illustrated that an endo-1,4-β-mannanase derived from Aspergillus niger could be immobilised successfully, for use in a recyclable reaction to produce MOS products. This study also described the successful use of SBM-sugars as a prebiotic, indicating a successful alternative to antibiotic growth promoters (AGP) by illustrating their positive effect on inhibiting growth of pathogenic bacterial species. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology & Bioinformatics, 2024
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- Date Issued: 2024-10-11
Spatiotemporal recharge determination in response to episodic rainfall events within the Central Karoo, South Africa
- Authors: Williams, Aarifah
- Date: 2024-04
- Subjects: Groundwater -- South Africa -- Beaufort West , Groundwater recharge , Hydrogeology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/64459 , vital:73735
- Description: With inadequate and unpredictable rainfall patterns resulting in a mean annual precipitation of 464 mm, South Africa is classified as a water-stressed semi-arid country. Consequently, between 2015 and 2021, the majority of South Africa was confronted with severe drought conditions, with numerous dams running dry across the country. The Beaufort West Municipality is a prime example of the adverse effects of South Africa's inadequate and erratic rainfall patterns. In Beaufort West, a town located within the Central Karoo region of the Western Cape, groundwater is the primary source of water. Since recharge within the region is episodic, occurring irregularly, understanding the dynamics surrounding recharge in the area is essential for achieving sustainable long-term water resource management. This study aimed to gain a better understanding of how the aquifers within the Beaufort West Municipality Well Fields respond to extended periods of drought, extreme episodic precipitation events and excessive abstraction. This study aimed to quantify extreme recharge in the Beaufort West municipal wellfields using the water-table fluctuation (WTF) method. Additionally, it sought to deepen comprehension of the local climate's interaction with groundwater levels, surface water dynamics, and recharge through a 32-year historical data analysis (1990 to 2022) encompassing precipitation, evaporation, and surface water parameters. Findings revealed the complex relationship between precipitation, evaporation, regional geology, and water abstraction, influencing recharge periods, duration, and mechanisms across different regions within the aquifer system. Groundwater levels exhibited rapid declines during droughts due to extensive well field abstraction, but recovery was evident following episodic high precipitation events in 1993, 1996, 2010/2011, and 2019/2020. This comprehensive analysis serves as a valuable foundation for informed water resource management strategies, emphasizing the need for diversified approaches ensure the long-term water security and resilience of the Beaufort West Municipality. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2024
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- Date Issued: 2024-04
Year-end oversight in Local Government: a case study of water and sanitation service delivery at Amathole District Municipality
- Authors: Seoke, Duncan
- Date: 2023-10-13
- Subjects: Municipal services South Africa Amathole District Municipality , Municipal reports , Local government South Africa Amathole District Municipality , Urban sanitation South Africa Amathole District Municipality , Municipal water supply South Africa Amathole District Municipality
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425206 , vital:72219
- Description: Poor service delivery is a challenge that has continued to plague the constitutional democracy of South Africa. Legislation has, in response, been passed to ensure efficient service delivery. Despite this legislation, municipal service delivery has been alarmingly poor, and reports on municipal performance and newspaper articles have corroborated this. On the causes of poor service delivery, the existing literature appears to have focused on financial mismanagement, corruption, and the incapacity of officials. Absent from existing literature are discussions on how municipal service delivery is affected by the lack of interrelatedness between municipal public resource management processes (such as revenue collection, expenditure management and oversight). This dissertation addresses this gap by examining the municipal public resource management processes from an oversight perspective. The study sought to analyse the effectiveness of year-end oversight at Amathole District Municipality (ADM) over water and sanitation services. This research aimed to study the year-end oversight over service delivery with reference to the Municipal Public Resource Management (MPRM) model. According to the model, effective service delivery includes inter alia effective oversight, as oversight forms part of the entire system of the municipal resource management cycle. Thus, for the MPRM model, oversight should be exercised on all these processes. The research was a desktop analysis that used both a qualitative and quantitative research methodology. The primary document analysed was the ADM Oversight Report (OR). This report is produced by the Municipal Public Accounts Committee (MPAC) and reflects the year-end oversight conducted by the MPAC on the municipality's activities. In the analysis of the OR, it was concluded that the ADM MPAC had failed to conduct effective year-end oversight of W&S services. The efficacy of the ADM MPAC's year-end oversight was measured against guidelines for effective year-end oversight from the National Treasury and the MPRM model. The findings suggested that there were inefficiencies in the manner that the ADM MPAC exercised its year-end oversight. , Thesis (MA) -- Faculty of Humanities, Sociology, 2023
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- Date Issued: 2023-10-13
Innovation in ecological restoration techniques: Enhancing Portulacaria afra survivorship in degraded arid thicket
- Authors: Norman, Yondela Masande
- Date: 2023-03-31
- Subjects: Land degradation South Africa , Subtropical Thicket Ecosystem Planning , Portulacaria afra , Restoration ecology , Nurse plants
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419276 , vital:71630
- Description: The Albany Thicket Biome has undergone extensive degradation over the past century, particularly from overstocking of livestock in the arid types of thicket. The degradation of the biome, coupled with little to no natural recovery, prompted the South African Government to implement the Subtropical Thicket Restoration Programme (STRP) in the early 2000s to rehabilitate degraded thicket using unrooted Portulacaria afra truncheons. The STRP also sought to create job opportunities, bring about social upliftment, promote biodiversity conservation and incentivise farmers and landowners in the region to promote carbon trading and farming of P. afra using carbon credits. However, the survivorship of P. afra planted using the STRP planting protocol has been less than ⁓30% because they are planted in degraded areas, where the truncheons are subjected to harsh biophysical conditions such as hard, capped soil, high soil temperatures, drought and herbivory. The aim of this study, therefore, was to improve the survivorship of P. afra planted in degraded thicket to at least 30%, using modified planting methods. In this study, four treatments were applied in 210 pondings (or micro-dams), each with P. afra planted in them (the first three treatments used rooted cuttings). The first treatment involved watering regimes where pondings were watered at varying frequencies. The second treatment involved planting companion species alongside P. afra while the third treatment involved planting P. afra underneath a nurse canopy. In the fourth treatment, unrooted P. afra truncheons were planted inside pondings. The mean survivorship of the P. afra cuttings was assessed 18 months after planting. The watering regime treatments, including the control, all yielded a survivorship of over 75%, with the significantly highest levels of survivorship being displayed in the weekly watering treatment (90.9 ± 6.8%) (p < 0.01). The companion plant treatment also produced a high mean survivorship of P. afra (94.9 ± 3.6%), significantly higher than that of the nurse plants (87.5 ± 6.3%) (p < 0.01). Among the unrooted truncheons it was found that untreated truncheons had the highest survivorship (76.2 ± 17.6%), with the lowest mean being found in truncheons that were both pruned and scarified (70.8 ± 20.8%), suggesting that this treatment, out of all of them, is the least successful under the prevailing environmental conditions in the study area. However, there was no significant differences among the unrooted truncheon treatments and their respective survivorship values to further substantiate this assertion (p = 0.26). Findings in this study also suggest that planting P. afra cuttings under a nurse plant was ideal for P. afra survivorship due to the nurse plant’s ability to ameliorate the microclimate under which the cuttings can establish and grow. Despite the soil under the nurse canopy having a significantly lower mean soil water potential (-160.9 ± 200.5 kPa), compared to the open areas (-73.4 ± 55.7 kPa) (p = 0.04), the pondings under the nurse canopy still had a lower mean soil temperature (31.4 ± 5.25°C) than the treatments in the open areas (38.5 ± 2.7°C), during the harsh midday sun. These favourable characteristics are reflected in the P. afra cuttings under a nurse canopy having a higher chlorophyll fluorescence (0.76 ± 0.06). compared to those planted in open areas (0.73 ± 0.13), suggesting that the P. afra cuttings in the former treatment had a higher photosynthetic efficiency compared to those in the latter, despite there being no statistically significant difference in chlorophyll fluorescence between the treatments (p = 0.14). Although these findings suggest that applying these modifications to planting P. afra, having achieved its objective of increasing survivorship to well over 50%, is likely to produce favourable results not only in overall survivorship, but also in fast-tracking arid thicket rehabilitation and restoration, further research on these rehabilitation techniques and their effectiveness is required. Furthermore, the downside to these treatments is that they are costly and time consuming, which puts the feasibility of large-scale programmes using these applications into question. Further investigation is required to determine ways in which the cost-effectiveness of these applications can be enhanced. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-03-31
Microbial and extracellular polymeric substance dynamics in arid–zone temporary pan ecosystems
- Authors: Bute, Tafara Frank
- Date: 2023-03-29
- Subjects: Extracellular polymeric substances , Biofilms , Vernal pools , Microbiomes , Sediment–water interface
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422258 , vital:71925
- Description: Microbial communities of bacteria, viruses, algae, protozoans and fungi participate profoundly in aquatic systems, particularly in mediating processes such as primary production, decomposition, and biogeochemical cycles. In addition, microbiomes produce extracellular polymeric substances (EPS) which encompass a hydrated exopolymer mainly constituted of carbohydrates and proteins. The exopolymer aid proliferation and persistence of biofilms on their resident surfaces. There is however paucity of data on functional diversity of microbiomes in arid zone temporary wetlands with previous research having mainly focused on permanent systems in the northern hemisphere. In the face of ongoing climatic changes and anthropogenic threats to wetlands, it is imperative to assess the health status of aquatic systems in relation to microbial productivity dynamics. In this thesis, colorimetric methods and sequence–based metagenomics were conducted to quantify microbial EPS production and bacterial metagenome functions, respectively. This study was conducted in Khakhea–Bray region (North–West, South Africa) in June 2021 and January 2022 with a focus on evaluating microbial patterns of distribution between seasons (i.e., Dry and Wet) and varying depth i.e., deepest zones (Deep), intermediate depth (Mid) and shallowest regions (Edge). Additionally, potential relationships between EPS and either water content or organic matter content (OM content) were evaluated. In this study it was hypothesized that wet phases and deeper zones will have high EPS production and support more functions in comparison to shallowest regions and dry phases. Carbohydrates and proteins were quantified using the Dubois method and modified Lowry procedure, respectively. Carbohydrates generally occurred in higher proportions than proteins, suggesting that EPS found in these systems was largely diatom produced. The wet phases (wet season and inundation periods) supported more EPS production compared to the dry phases. The results of principal components analysis (PCA) and Spearman’s correlations suggested that EPS was highly correlated with sediment water content among other assessed variables. No significant associations were established between EPS and organic matter content. Spatial distribution of EPS demonstrated similar patterns between the deepest (Deep) and the intermediate depth zones (Mid) however the shallow regions (Edge) had significantly lower concentrations. Bacterial characterization was established by amplification of the 16S rRNA gene using illumina–sequencing protocol. Enzyme functions associated with biogeochemical pathways were predicted in PICRUSt2 bioinformatics pipeline. A total of 15 042 Unique Amplicon Sequence Variants (ASVs) were observed to be affiliated to 51 bacterial phyla and 1 127 genera. All top genera had commonality in heat tolerance. Firmicutes, dominated at phyla level with 59 % (mean ± sd, 19 ± 13 %) relative abundance followed by Actinobacteria and Proteobacteria both at 34 % (18 ± 7 %) and (18 ± 6 %), respectively. Microbial diversity matrices highlighted significant differences in beta diversity more than alpha diversity. Bacterial microbiomes were more distinct between seasons compared to within season, suggesting that functions were seasonally driven. These findings were supported by highest rates of denitrification, carbohydrate degradation and EPS production by core microbiomes in the wet season as compared to low rates of nitrogen mineralisation, carbon fixation and nitrification in the dry season. The present findings represent a first attempt in evaluating sequence–based metagenomics in semi–arid southern African temporary pan ecosystem. Both microbial EPS and bacterial functional potential were highly driven by water availability, with highest rates mainly associated with maximum inundation compared to dry states of pans. It can therefore be suggested that extended dry periods are threatening to microbially mediated processes in temporary wetlands, with implications to loss of biodiversity due to desiccation resulting in poor nutrient cycling. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-03-29
Identification of novel compounds against Plasmodium falciparum Cytochrome bc1 Complex inhibiting the trans-membrane electron transfer pathway: an In Silico study
- Authors: Chebon, Lorna Jemosop
- Date: 2022-10-14
- Subjects: Malaria , Plasmodium falciparum , Molecular dynamics , Antimalarials , Molecules Models , Docking , Cytochromes , Drug resistance , Computer simulation , Drugs Computer-aided design , System analysis
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365666 , vital:65774 , DOI https://doi.org/10.21504/10962/365666
- Description: Malaria continues to be a burden globally with a myriad of challenges deterring eradication efforts. With most antimalarials facing drug resistance, such as atovaquone (ATQ), alternative compounds that can withstand resistance are warranted. The Plasmodium falciparum cytochrome b (PfCytb), a subunit of P. falciparum cytochrome bc1 complex, is a validated drug target. Structurally, cytochrome b, cytochrome c1, and iron sulphur protein (ISP) subunits form the catalytic domain of the protein complex having heme bL, heme bH and iron-sulphur [2FE-2S] cluster cofactors. These cofactos have redox centres to aid in the electron transfer (ET) process. These subunits promote ET mainly through the enzyme’s ubiquinol oxidation (Qo) and ubiquinone reduction (Qi) processes in the catalytic domain. ATQ drug has been used in the prevention and treatment of uncomplicated malaria by targeting PfCytb protein. Once the mitochondrial transmembrane ET pathway is inhibited, it causes a collapse in its membrane potential. Previously reported ATQ drug resistance has been associated with the point mutations Y268C, Y268N and Y268S. Thus, in finding alternatives to the ATQ drug, this research aimed to: i) employ in silico approaches incorporating protein into phospholipid bilayer for the first time to understand the parasites’ resistance mechanism; ii) determine any sequence and structural differences that could be explored in drug design studies; and iii) screen for PfCytb-iron sulphur protein (Cytb-ISP) hit compounds from South African natural compound database (SANCDB) and Medicines for Malaria Venture (MMV) that can withstand the identified mutations. Using computational tools, comparative sequence and structural analyses were performed on the cytochrome b protein, where the ultimate focus was on P. falciparum cytochrome b and its human homolog. Through multiple sequence alignment, motif discovery and phylogeny, differences between P. falciparum and H. sapiens cytochrome b were identified. Protein modelling of both P. falciparum and H. sapiens cytochrome b - iron sulphur protein (PfCytb-ISP and HsCytb-ISP) was performed. Results showed that at the sequence level, there were few amino acid residue differences because the protein is highly conserved. Important to note is the four-residue deletion in Plasmodium spp. absent in the human homolog. Motif analysis discovered five unique motifs in P. falciparum cytochrome b protein which were mapped onto the predicted protein model. These motifs were not in regions of functional importance; hence their function is still unknown. At a structural level, the four-residue deletion was observed to alter the Qo substrate binding pocket as reported in previous studies and confirmed in this study. This deletion resulted in a 0.83 Å structural displacement. Also, there are currently no in silico studies that have performed experiments with P. falciparum cytochrome b protein incorporated into a phospholipid bilayer. Using 350 ns molecular dynamics (MD) simulations of the holo and ATQ-bound systems, the study highlighted the resistance mechanism of the parasite protein where the loss of active site residue-residue interactions was identified, all linked to the three mutations. The identified compromised interactions are likely to destabilise the protein’s function, specifically in the Qo substrate binding site. This showed the possible effect of mutations on ATQ drug activity, where all three mutations were reported to share a similar resistance mechanism. Thereafter, this research work utilised in silico approaches where both Qo active site and interface pocket were targeted by screening the South African natural compounds database (SANCDB) and Medicines for Malaria Venture (MMV) compounds to identify novel selective hits. SANCDB compounds are known for their structural complexity that preserves the potency of the drug molecule. Both SANCDB and MMV compounds have not been explored as inhibitors against the PfCytb drug target. Molecular docking, molecular dynamics (MD) simulations, principal component, and dynamic residue network (DRN; global and local) analyses were utilised to identify and confirm the potential selective inhibitors. Docking results identified compounds that bound selectively onto PfCytb-ISP with a binding energy ≤ -8.7 kcal/mol-1. Further, this work validated a total of eight potential selective compounds to inhibit PfCytb-ISP protein (Qo active site) not only in the wild-type but also in the presence of the point mutations Y268C, Y268N and Y268S. The selective binding of these hit compounds could be linked to the differences reported at sequence/residue level in chapter 3. DRN and residue contact map analyses of the eight compounds in holo and ligand-bound systems revealed reduced residue interactions and decreased protein communication. This suggests that the eight compounds show the possibility of inhibiting the parasite and disrupting important residue-residue interactions. Additionally, 13 selective compounds were identified to bind at the protein’s heterodimer interface, where global and local analysis confirmed their effect on active site residues (distal location) as well as on the communication network. Based on the sequence differences between PfCytb and the human homolog, these findings suggest these selective compounds as potential allosteric modulators of the parasite enzyme, which may serve as possible replacements of the already resistant ATQ drug. Therefore, these findings pave the way for further in vitro studies to establish their anti-plasmodial inhibition levels. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2022
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- Date Issued: 2022-10-14
Settling in: Investigating the experiences of social media use of a group of international students in their integration into the Rhodes University environment
- Authors: Losa Reinoso, Kelia
- Date: 2022-10-14
- Subjects: Students, Foreign South Africa , Social media and society South Africa , Students, Foreign Social conditions , Student adjustment South Africa , Students, Foreign Social networks , Social media and college students South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/405941 , vital:70221
- Description: The South African government and its institutions of higher education take deliberate measures to attract international students to this country which is marketed as an appealing option for for international study because it is cheaper than in European countries and the US, courses that may be unavailable or difficult to get into in their home countries are available in South Africa, there is a high quality of education, a greater variety of qualifications, technologically advanced facilities and a geographical proximity of South Africa to international students’ home countries in the SADC region. While many international students find living in a new country exciting, fulfilling and stimulating, it may at the same time be frustrating and confusing. Students may find it difficult to adjust to their general living arrangements, new housing and transportation environments and dealing with financial and health care concerns. Also, there may be academic challenges and socio-cultural difficulties to navigate. Problems of adjustment may force international students into isolation, creating feelings of alienation and so they develop mechanisms to adjust, to feel better integrated and cope with situations that they might find difficult and alienating. One of the most important of these is to find social support which can come from friends, family, academic staff, classmates or colleagues. Social networking through social media is also important as it can ameliorate feelings of alienation and contribute significantly to the creation of an active social network and its use is therefore associated with social support for, and social adjustment of international students. This study investigates the positive and negative impacts of social media on the integration of international students into the Rhodes University environment. The study uses an exploratory survey, focus groups and semi-structured interviews to gather data which was analysed using a thematic analysis. This analysis shows that international students make use of a variety social media platforms, each with its own specific purpose – WhatsApp to communicate with friends and family, Twitter for news, Instagram for entertainment and Facebook for information and entertainment, etc. Interestingly, while social media is used in the maintenance of strong social connections it is not used to create those relationships. Rather, meeting new people and the initiation and building of relationships was done through meeting at parties and pubs and in university organised social events, clubs and societies. While social media reporting of issues like xenophobic attacks made international students anxious, none of those involved in the study were subjected to such attacks through social media. , Thesis (MA) -- Faculty of Humanities, School of Journalism and Media Studies, 2022
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- Date Issued: 2022-10-14
Teachers’ practice in developing visually impaired learners’ reading skills in the junior primary phase in northern Namibia
- Authors: Nuugonya, Elizabeth Nangula
- Date: 2022-10-14
- Subjects: Children with visual disabilities Education Namibia Oshana , Reading (Elementary) Namibia Oshana , Inclusive education Namibia Oshana , Convention on the Rights of Persons with Disabilities and Optional Protocol (2007 March 30) , Braille Study and teaching (Elementary) Namibia Oshana , Teachers of the blind Namibia Oshana
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/405379 , vital:70166
- Description: Namibia has adopted, ratified and followed several international policies on disability and inclusive education including the United Nations Convention on the Rights of Persons with Disabilities (UNCRPD). Since 2014, the Namibian education system has been working towards the implementation of the Sector Policy on Inclusive Education to promote an education system that is accessible, inclusive, equitable and of good quality (Namibia. Ministry of Education, Arts and Culture: Sector Policy on Inclusive Education, 2013). The policy aims to address barriers faced by learners with disabilities and how teachers develop ways of teaching that respond to the individual differences. Reading in a second language tends to develop more slowly by visually impaired learners, although the Junior Primary Phase syllabus promotes equal opportunity for all learners to participate in reading equally irrespective of learners’ disabilities. Teachers should understand how to teach and accommodate learners who are visually impaired and all reading materials should be fit for purpose and support these learners appropriately. Thus, this study explores how Junior Primary teachers develop visually impaired learners’ reading skills to provide accessible education to them. Learning to read is challenging for most learners, but even more for learners who are visually impaired. Learning to read braille is a complex process, far more than reading print texts. This study seeks to examine how learners are taught to read using braille in a school for visually impaired learners in Namibia, Oshana region. The motivation for this research study was twofold - firstly, my interest in the development of reading skills with visually impaired learners was aroused by my teaching experience. Secondly, due to my realisation that the area was under-researched in Namibia; I wanted to fill the existing gap in the development of reading skills in braille and print. The study critically engaged teachers to help me obtain an understanding of how they develop reading instructions with visually impaired learners and the factors that enabled the development of braille literacy and the challenges that hampered the development of reading skills. The study took the qualitative case study approach underpinned by an interpretivist orientation. Data was collected using semi-structured observation during reading lessons and focus group interviews. The Theory of Practice Architectures (ToPA) was used as a lens to analyse the promoting and constraining factors in teaching visually impaired learners reading skills. The study found that teachers used different reading methods to promote the development of reading skills such as reading aloud, tactile methods and phonics. The study further noted that teachers mostly created their own reading materials due to the lack of reading materials and reading books printed in braille. Although learners were supported during reading, the challenge of developing reading skills with visually impaired learners remains a challenge. I hope that the findings from this research study strengthen the development of reading skills in all special schools and contribute to the creation of knowledge on the development of reading skills with visually impaired learners in Namibia. As a means to further support learners who experience visual impairments, this study recommends that more formative research studies on the notion of teachers’ practice in developing reading skills with visually impaired learners should be conducted to bring about change. , Thesis (MEd) -- Faculty of Education, Education, 2022
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- Date Issued: 2022-10-14
Understanding resource partitioning in three species of Gobiidae living in the warm-temperate Sundays Estuary
- Authors: Ndaleni, Phumza Malibongwe
- Date: 2022-10-14
- Subjects: Gobiidae South Africa Sundays Estuary (Eastern Cape) , Gobiidae Reproduction , Gobiidae Food , Gobiidae Geographical distribution , Gobiidae Morphology , Resource partitioning (Ecology)
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/365655 , vital:65773 , DOI https://doi.org/10.21504/10962/365655
- Description: Estuaries represent a transition zone where saline water combines with freshwater, and this results in temporal and spatial variability in both biotic and abiotic parameters. Because the environmental gradient changes so rapidly in areas and the estuarine environment is harsh, fish need to either be able to specialise to one particular suite of abiotic contexts or have the physiological mechanisms to allow them to move throughout the gradient of the estuary. Apart from this, other factors such as climate change, habitat degradation, over exploitation of resources and the introduction of alien species also negatively influence fish species living in estuaries. These anthropogenic stressors can cause species exclusion in areas which were previously suitable for species with particular suites of traits. Measuring resource partitioning within functional groups not only helps in determining the functional structure of communities but also explains how organisms use resources in a community. Resource partitioning studies provide a useful conceptual framework to understand species interactions in a community and identify major resource dimensions along which species segregate. This study aimed to describe resource partitioning among the Gobiidae species, as the family is well represented in South African estuaries (24 species), is highly abundant and has several species which co-exist in individual estuaries. To accomplish this, different forms of resource partitioning that promote the coexistence of the three most abundant species found in warm-temperate South African estuaries; the Knysna sand goby Psammogobius knysnaensis (Smith, 1935), Prison goby Caffrogobius gilchristi (Boulenger, 1898) and River goby Glossogobius callidus (Smith, 1937) were investigated in the Sundays Estuary. This was accomplished by determining the reproductive biology, interspecific differences in feeding morphology, feeding ecology and habitat partitioning among the three species. The distribution and abundance of potential prey in the estuary (mesozooplankton and macrozoobenthic communities) were investigated, with both mesozooplankton and macrozoobenthic communities grouping into three distinct communities along the environmental gradient. Feeding morphological traits responsible for prey location, chasing, capture, mastication, ingestion and digestion were investigated. Little morphological overlap was observed between P. knysnaensis and C. gilchristi, indicating little dietary overlap between these two species. In contrast, the feeding morphology of Glossogobius callidus overlapped with both P. knysnaensis and C. gilchristi, indicating the potential to compete with both species for food. The trophic ecology of the three species was investigated using stomach content analysis, whereby prey abundance, frequency of occurrence and percentage of volume were determined. For P. knysnaensis, the incorporation of cyclopoids and ostracods decreased with fish size and that of bivalves and amphipods increased. Caffrogobius gilchristi was found to be a specialist feeder on cyclopoids but as the species increased in size the incorporation of amphipods, mysids, brachyurans and gastropods increased. Glossogobius callidus was found to be a generalist feeder, feeding on cyclopoids, amphipods and chironomids. The incorporation of cyclopoids decreased with fish size and the consumption of large sized amphipods and chironomids increased with fish size. To assess their reproductive biology, gonadosomatic index (GSI) was used to study the breeding season. In all three species, reproduction peaked in spring and summer, and this is associated with peak phytoplankton and zooplankton biomass in estuaries. Length at 50% maturity and fecundity were also determined. The three species predominated in different locations in the estuary, which explains why they were able to use similar resources and reproduce at the same time. Psammogobius knysnaensis was abundant in the sandy mouth region, with sediment type and prey (bivalves and mysids) availability affecting its distribution. Caffrogobius gilchristi was abundant in the muddy lower reaches of the estuary, with its distribution influenced by sediment composition and temperature. Glossogobius callidus was abundant in the turbid upper reaches, with its distribution influenced by prey (amphipods) availability and turbidity. Different habitat preferences and diet among the specific size ranges enabled coexistence among the species. This explains the high abundances and coexistence of gobies in South African estuaries. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
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- Date Issued: 2022-10-14
Limits of the Judiciary in the separation of powers in South Africa
- Authors: Qikani, Siphokazi
- Date: 2022-08
- Subjects: Judiciary and law
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/11260/9460 , vital:73539
- Description: The Constitution of the Republic of South Africa, 1996 is the supreme law of the Republic and obligations imposed by it must be fulfilled. The laws of the country and government action draw their validity from the Constitution. The Constitution entrenches principles that ensure democratic processes which promote the objectives, spirit and purport of the Constitution. Separation of powers is one of such principles. Separation of powers is the doctrine that proposes division of power between the legislative, executive, and judicial branches of government. The Constitution confers legislative power to parliament, executive power to the executive and judicial power to the courts. In the South African context of separation of powers, the role of each branch of government is not always clearly defined and sometimes gains perspective as courts interpret parliamentary legislations and executive policies. The Court’s role and limitations in the interpretation of laws often come under scrutiny and bring confusion as to what extent can courts intervene in matters purely left to other branches of government. The current study explores the meaning, implications and practical application of the doctrine of separation of powers by courts. The study pays particular attention to the role and the limits of the Judiciary within the context of separation of powers in South Africa, with the hope of bringing greater clarity of this doctrine to lawyers, academics, government officials and society at large. Keywords: constitutional supremacy, rule of law, separation of powers, legislature, executive, judiciary, judicial intervention. , Thesis (Masters) -- Faculty of Humanities Social Sciences and Law, 2022
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- Date Issued: 2022-08
An eco-physiological investigation of fisheries-induced evolution: comparing the resilience of larvae from exploited and unexploited commercial reef fish populations to projected ocean acidification
- Authors: Muller, Cuen
- Date: 2022-04-08
- Subjects: Ocean acidification , Fishes Climatic factors , Fishes Physiology , Fishes Metabolism , Fishes Respiration , Fishes Larvae , Fishery management , Chrysoblephus laticeps (Red roman)
- Language: English
- Type: Doctoral thesis , text
- Identifier: http://hdl.handle.net/10962/232579 , vital:50004 , DOI 10.21504/10962/232579
- Description: It is now accepted that anthropogenic-induced climate change is resulting in unprecedented rates of change to marine environments. Marine organisms are being challenged by rapidly increasing temperatures, acidification, expansion of oxygen dead zones, and higher frequencies and magnitudes of extreme weather events. Exploited fish populations are also undergoing selective harvesting. Certain traits, such as large size, fast growth, and/or bold/active behaviours, are being actively targeted and removed from the population gene pool. This selective removal of individuals may compromise the capacity of fish populations to resist or recover from environmental disturbances and reduce their ability to adapt to a changing environment as many of these traits are heritable. As most marine fishes' embryonic and larval stages represent the period when individuals are most sensitive to environmental disturbances, they are a critical bottleneck to population persistence in the face of exploitation and climate change. This thesis aimed to quantify and compare the metabolic physiology, growth, and development of an exploited and endemic sparid, the roman seabream Chrysoblephus laticeps, during the early larval stages under 1) ocean acidification conditions expected by the year 2100 and 2) from populations experiencing dissimilar rates of exploitation. To quantify and compare the physiology of larvae, adult C. laticeps from an exploited population were captured and field-spawned. Fertilised eggs were placed into either control/present-day conditions (pH = 8.03, pCO2 ≈ 420 μatm) or high-pCO2/hypercapnic treatment conditions (pH = 7.63, pCO2 ≈ 1400 μatm). The metabolic physiology of individual larvae was determined using a novel rolling-regression technique on static respirometry data. Here, estimates of the minimum and maximum oxygen consumption rates (VO2) could be determined with high test-retest reliability. The very early developmental stages (yolk-sac stage) appeared resilient to high pCO2 conditions despite being exposed to treatment conditions throughout the embryonic stage. Preflexion larvae showed sensitivity to treatment conditions by exhibiting reduced metabolic and growth rates, consistent with metabolic depression, associated with environmental stress. However, by the onset of flexion, which coincides with gill development, acid-base regulation, and muscle differentiation, metabolic and growth rates of treatment larvae were significantly greater than that of controls. This suggests that acid-base regulation imposes a high cost to maintain internal pH homeostasis. Importantly, these elevated metabolic costs were likely mediated through increased feeding rates in experimental conditions where food was ad libitum. In natural conditions, where food availability may be varied, high pCO2 conditions could be associated with higher mortality rates. Based on evidence that protected/unexploited populations are more genetically diverse and are composed of individuals representing a greater range of metabolic phenotypes, offspring were collected from a protected population experiencing otherwise similar environmental conditions to the exploited population. Metabolic rates of control larvae were generally similar to those of the exploited population. However, minimum rates of VO2 were typically higher for larvae from the protected population at comparable life stages. Preflexion treatment larvae from the protected population did not appear to undergo a period of reduced metabolism or growth compared to their control counterparts. While metabolic rates at the onset of flexion were significantly higher for treatment larvae, this was not associated with growth differences. Growth over-compensation following periods of growth depression is often associated with deleterious effects, such as organ damage and body or developmental malformations. This suggests somewhat improved resilience to ocean acidification conditions. This thesis found evidence that larval C. laticeps are sensitive to ocean acidification conditions expected by 2100. When this stressor is combined with increasing thermal variability, changing current coastal regimes, and heterogeneous food availability, also expected to occur by 2100, ocean acidification may compromise the population persistence of this species. However, an energetics approach to stress-tolerance suggests that larvae from the protected population may inherently show greater resilience to climate change-related environmental stressors. Evidence that exploitation affects the resilience of fish larvae to climate change highlights the need for an evolutionary approach to fisheries management and the importance of spatial protection in maintaining larger and more resilient populations while providing the raw material essential for adaptation. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
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- Date Issued: 2022-04-08
Magnitude
- Authors: Seddon, Deborah Ann
- Date: 2022-04-07
- Subjects: Creative writing (Higher education) South Africa , Zimbabwean poetry (English) 21st century , Diaries -- Authorship , Polish literature 21st century History and criticism , English poetry 20th century History and criticism , English literature Irish authors History and criticism , American poetry 21st century History and criticism
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/234400 , vital:50192
- Description: My thesis is a collection of lyric, narrative, and prose poetry directed towards two forms of death – physical death and the disavowal of the self. Many poems focus on the death of my mother, and the work required after loss to sort through a family’s life in my Harare childhood home. This associative exploration draws together childhood memories, encounters with physical objects, letters, and songs, as well as with the city and its people. Tadeusz Rózewicz’s Mother Departs has influenced my approach to writing of my mother’s death, particularly how to grant her a voice in the telling. I also draw on the poetry of Harmony Holiday and Pascal Petite, in their attention to the complexities and emotional dangers of the mother-daughter bond. Other poems draw on the work of Adrienne Rich, Audre Lorde, Judy Grahn, Ocean Vuong, and Saeed Jones, in terms of imagining queer life into poetry, the use of the erotic as a means of empowerment, and developing a queer political identity, to examine various aspects of queer love, including the heartaches associated with self-denial. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2022
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- Date Issued: 2022-04-07
A 5G Communication system based on flexible spectrum technology for the SKA
- Authors: Karembera, Reinhard Siwombe
- Date: 2022-04
- Subjects: Mobile communication systems--Technological innovations , Wireless communication systems -- Standards --South Africa
- Language: English
- Type: Doctoral theses
- Identifier: http://hdl.handle.net/10948/56177 , vital:56013
- Description: Faculty of Science Radio astronomy research is rapidly expanding across the African continent. At the same time, the fifth generation (5G) of mobile communication systems are also being researched and developed. Throughout history, mobile communication networks are known to affect the activities of radio astronomy. If not carefully managed, radio frequencies from mobile communication devices can severely affect radio astronomy observations. To that end, many techniques have been proposed to protect the radio astronomer from RFIs coming from radio communication networks. Some of the proposed techniques such as RFI quite zones and spectrum assignment by regulatory authorities will not be convenient during the implementation of 5G mobile networks. This is because 5G radio communication systems are expected to support spectrum-hungry application such as video-on-demand, augmented realities, high-definition television and so on. To realize this, the 5G networks will be forced to have access to protected radio spectrum, including those at which radio astronomy activities are being researched. To facilitate this, the 5G radio communication networks should have the intelligence to coexist within such protected spectrums without the consequences of radio frequency interferences (RFI) to the primary user. In this thesis, we present novel 5G networks with the intelligence that allow them to coexist within radio astronomy areas without introducing RFIs to the primary user. We proposed a photonic solution, keeping in mind the characteristic requirements for future 5G radio communication networks. The thesis begins by reviewing the current trend of radio astronomy research in Africa. It was found that radio astronomy research in Africa is growing rapidly. Many African countries such as South Africa and Ghana are at advanced stages when it comes to radio astronomy research. Therefore, the finding and proposal of this thesis will be valuable to such countries. In order to develop a radio access network (RAN) that can coexist within radio astronomy areas, the thesis reviewed past and present state-of-the-art RANs. Each access network was analyses for its feasibility to be implemented within radio astronomy areas to realize mobile communication without the consequences of RFIs to the astronomer. It was motivated that the current centralized radio access network (C-RAN) the best solution to be developed for radio communication within radio astronomy areas. This is because the C-RAN architecture is centralized by pooling network resources to a common point. From such pool, network resources can be controlled and shared among 5G network user, including radio astronomers and the surrounding communities. The next chapters reviewed photonic RF transmitters and their associated lasers currently being proposed to be used within C-RANs. , Thesis (PhD) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
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- Date Issued: 2022-04
Potential Synergism between Entomopathogenic Fungi and Entomopathogenic Nematodes for the control of false codling moth (Thaumatotibia leucotreta)
- Authors: Prinsloo, Samantha Lee
- Date: 2021-10
- Subjects: Cryptophlebia leucotreta , Entomopathogenic fungi , Insect nematodes , Citrus Diseases and pests , Cryptophlebia leucotreta Biological control , Pests Integrated control , Biological pest control agents
- Language: English
- Type: Masters theses , text
- Identifier: http://hdl.handle.net/10962/188832 , vital:44790
- Description: False codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) (FCM), is a major phytosanitary pest of citrus in South Africa. Sufficient control measures for the soil-dwelling life stages of FCM have yet to be identified and owing to restrictions on the use of insecticides, non-chemical control options have been investigated including the use of entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPN). Laboratory and field trials on an indigenous EPF, Metarhizium anisopliae FCM Ar 23 B3, have shown that this isolate is capable of inducing mortality in FCM soil-dwelling life stages. Other agents that have been highlighted as potential controls for soil-dwelling FCM life stages are the EPN species Steinernema yirgalemense 157-C, S. jeffreyense J194 and H. noenieputensis 158-C. This study conducted laboratory bioassays to assess the virulence of these four control agents on fifth instar FCM, in 24-well plates. These results reaffirmed the virulence of the four microbial control agents at their recommended doses of 50 IJs (EPN) and 1×107 conidia/ml (EPF) against fifth instar FCM with 80 to 96% larval mortality recorded. The EPF isolate exhibited the lowest mortality whilst S. yirgalemense induced the greatest mortality. In addition, the lethal concentration (LC) values for each isolate were determined using dose response bioassays. These values were previously unknown for all EPN species and for the EPF isolate based on the methodology used in this study. The LC50 results in order from lowest to highest EPN IJ concentration requirements were 4.38 IJs (S. yirgalemense), 4.47 IJs (S. jeffreyense) and 7.11 IJs (H. noenieputensis). The EPF isolate exhibited an LC50 of 3.42×105 conidia/ml. Lastly, research has shown that the combination of two control agents may increase control of late instar lepidopteran and coleopteran larvae, through synergistic interactions. Thus, the interactions that occurred between the combination of these EPN species with the EPF isolate were determined. This study found that when all three EPN species were combined simultaneously and sequentially with the EPF isolate M. anisopliae FCM AR 23 B3, additive interactions took place with exception of the simultaneous application of S. yirgalemense and H. noenieputensis, with the EPF and S. jeffreyense applied 24 h post EPF application. For the former, a synergistic interaction was found, whilst for the latter two, an antagonistic interaction. Although no strongly synergistic interactions were observed, additive interactions have been shown to reach a synergistic level when certain parameters are changed. Moving forward, a uniform methodology for conducting EPF/EPN interaction experiments has been suggested. It has also been recommended that due to the additive interactions observed in this study, laboratory soil-bioassays and field trials should be carried out for all three EPN species in combination with the EPF isolate. This research will inevitably facilitate the constant knowledge into management strategies for the phytosanitary pest, FCM in South African citrus. , Thesis (MSc) -- Science, Zoology and Entomology, 2021
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- Date Issued: 2021-10
A study of the catalysis of the Diels-Alder and Aldol Condensation Reactions
- Authors: Ndagano, Urbain Nshokano
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178525 , vital:42947
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
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- Date Issued: 2021-04
The Dragon in the News : how Malawian journalists perceive the political influence of China on news reporting in Malawi
- Authors: Nyirongo, Mwaona
- Date: 2021-04
- Subjects: Journalists -- Malawi , Journalism -- Malawi , Journalism -- Political aspects -- Malawi , Journalism -- Objectivity -- Malawi , China -- Foreign economic relations -- Malawi , Malawi -- Economic conditions , Malawi -- Politics and government
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/177907 , vital:42889
- Description: The arrival of China in Malawi has been characterised by a growing sense of uncertainty where academics and social commentators at large have expressed concern over the intentions of the super power in the country. There are fears that China would like to extend its influence to Malawi as part of a broader push, to have greater influence in global politics and economics. That push is in part exercised through the media. The thesis examined the perception of Malawian journalists on how news media reports on Chinese activities in Malawi. It used content analysis to understand how the mediascape had changed from 2001 – 2007 when China had not established diplomatic relations with Malawi, and January 2008 – 2020 when China had established diplomatic relations. The thesis examined these shifts in journalistic representations of China in Malawi and developed prompts and probes from which journalist interviews were conducted. From the content analysis, it appears there is a remarkable change in the way China has been covered from 2001 – 2020. From 2001 – 2007, Malawian media, especially The Daily Times, was very harsh on China, uncritically reproducing Western representations of China as an aggressive country with no respect for human rights and dignity. This changed after January 2008 when the media leaned towards tolerance and acknowledgement of Chinese activities. Through interviews, journalists have indicated that the Chinese government offers opportunities, such as scholarships, fellowships, and exchange visits to journalists, making it difficult for them to bite the finger that is feeding them. This ‘soft power’ is backed up by the repressive power of the Malawi government, which uses intimidation to force journalists to report in their favour, thereby helping create a positive picture for China in Malawi. Journalists report that the significant shifts in journalistic representations of China have been mirrored by changes in the conceptualisation of journalistic roles in Malawi’s mediascape. , Thesis (MA) -- Faculty of Humanities, Journalsim and Media Studies, 2021
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- Date Issued: 2021-04
The Effectiveness of Eskom’s transmission project team lationships in the delivery process
- Authors: Mpetshwa, Noninzi
- Date: 2015-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53318 , vital:45137
- Description: Eskom Holding is a public limited liability company that supplies electricity. It supplies approximately ninety-nine percent of the electricity used in South Africa, and approximately forty-five percent of that used in Africa. Eskom generates, transmits and distributes electricity to its customers. The Project Execution Department is a department in the Transmission Division that executes the capital and refurbishment of projects. The objective of the study was to discover the opinion of the project team members, on whether there is a lack of project-team efficiency in delivering the projects on time, and within the budget. Descriptive research methodology was used to investigate the objectives of the research. The data were obtained through the structured questionnaires that were hand-delivered and emailed. The research is limited to the Project Execution and Procurement Department in the Transmission Division. The research excludes the Capital Expansion Department (CED) project (Medupi, Kusile and Power Development Projects). The findings of the study showed that, Eskom’s Transmission Project Execution and Commercial Departments need to work hand-in-hand. This will avoid any unnecessary procurement delays which would have an impact on project delivery time. Continuous communication among the project team members could improve the efficiency and serve to build good relationships. Currently, projects are delivered late and over budget. This situation could lead to the outsourcing of departments or even to the redeployment of Senior Management. It would also have a negative impact on the cost and supply of electricity to the country. , Thesis (MSc) -- Faculty of Engineering, the Built Environment and Information Technology, School of the Built Environment and Civil Engineering, 2021
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- Date Issued: 2015-04