faces, disappearing
- Authors: Mbhele, Mbekezeli
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424952 , vital:72196
- Description: My thesis explores township life through the eyes of a young boy, Sengwayo, whose life changes when a strange man arrives unexpectedly to stay with his family. The man is introduced as his uncle but nothing further is said about him. Sengwayo soon begins to experience visions and decides to find out who this man really is. His search for truth soon becomes obsessive and culminates in tragedy. As we follow Sengwayo in his quest of uncovering the truth it becomes difficult to differentiate between Sengwayo’s imagination and reality. This thesis collapses the distance between what is and what could be. It does this by alternating short sentences mostly used in the poetry of maskanda lyrics, and in the stream of consciousness found in jazz improvisation. In literary terms, the thesis draws influence from the rants and rhyme schemes of Lesego Rampolokeng, the tone and pace of Sony Labou Tansi and the surrealism in Mangaliso Buzani’s work. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2023
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M3: Mining Mini-Halos with MeerKAT
- Authors: Trehaeven, Keegan Somerset
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424754 , vital:72181
- Description: This work aims to showcase the MeerKAT telescope’s capabilities and related calibration and imaging software in studying the emission of radio mini-halos. These diffuse radio synchrotron sources surround a Brightest Cluster Galaxy (BCG) in relatively relaxed clusters out to a few 100 kpc in size. They are difficult to image because of their relatively low surface brightness and small angular size. Hence, they could not be studied in great detail by previous generations of radio telescopes and much about their nature, particularly the exact production mechanism, is not yet fully understood. Thus, for the first time, MeerKAT observed a sample of five galaxy clusters to investigate the central radio mini-halo in each. Studying these sources requires the deepest images generated from the data and the effective subtraction of any projected sources obscuring or contaminating the underlying diffuse emission. Therefore, I describe the data reduction used to create third-generation calibrated, primary beam corrected, point source subtracted Stokes I L-band continuum images of these clusters. For first- and second-generation calibration, I use the CARACal pipeline, which implements software optimised explicitly for MeerKAT data. For third-generation calibration, I use the faceted approach of killMS and DDFacet, and then I perform visibility-plane point source subtraction to disentangle the compact and diffuse emissions. I then measured the size, flux density, in-band spectral properties, and radio power of the central mini-halos. I present the first new mini-halo detection by MeerKAT (MACS J2140.2-2339, Trehaeven et al. accepted), the first spectral index maps of these mini-halos, which show very interesting distributions, and a ∼100 kpc II southern extension to the ACO 3444 mini-halo previously unseen in archival VLA data. Thereafter, I present a multi-wavelength case study for two complementary mini-halos from our sample and show via a radio-to-X-ray spatial correlation test that they might be caused by different particle (re)-acceleration mechanisms. Through these initial science results, I have shown that future observations of radio mini-halos with MeerKAT are an exciting prospect that can lead to a better understanding of the fundamental physics behind these sources. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2023
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The application of statistical classification to predict sovereign default
- Authors: Vele, Rendani
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424563 , vital:72164
- Description: When considering sovereign loans, it is imperative for a financial institution to have a good understanding of the sovereign they are transacting with. Defaults can occur if proper evaluation steps are not considered. To aid in the prediction of potential sovereign defaults, financial institutions, together with grading companies, quantify the risk associated with issuing a loan to a sovereign by developing sovereign default early warning systems (EWS). Various classification models are considered in this study to develop sovereign default EWS. These models are the binary logit, probit, Bayesian additive regression trees, and artificial neural networks. This study investigates the predictive performance of the various classification techniques. Sovereign information is not readily available, so missing data techniques are considered in order to counter the data availability issue. Sovereign defaults are rare, which results in an imbalance in the distribution of the binary dependent variable. To assess data sets with such characteristics, metrics for imbalanced data are considered for model performance comparison. From the findings, the Bayesian additive regression technique generated better results than the other techniques when considering a basic data analysis. Moreover when cross-validation was considered, the neural network technique performed best. In addition, regional models had better results than the global model when considering model predictive capability. The significance of this study is to develop sovereign default prediction models using various classification techniques focused on enhancing previous literature and analysis through the application of Bayesian additive regression trees. , Thesis (MSc) -- Faculty of Science, Statistics, 2023
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The possible effect of insecticide drift from citrus orchards, and acute toxicity of insecticides on the biocontrol agents of Pontederia crassipes (Mart.) Solms-Laub (Pontederiaceae) established along citrus orchards in the Lowveld region of Mpumalanga Province, South Africa
- Authors: Mabuza, Mefika Michael
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424468 , vital:72156
- Description: This study investigated the possible effect of insecticide drift on naturalized biological control agents of Pontederia crassipes (Mart.) Solms-Laub (Pontederiaceae), in the Lowveld region of Mpumalanga Province of South Africa. Occurrence and abundance of biocontrol agents were recorded at three sites on the Crocodile River and at three dams adjacent to citrus orchards. Leaves of P. crassipes and water samples were collected for insecticide residues and also nutrient status of the water and plants. Eccritotarsus catarinensis Carvalho (Hemiptera: Miridae), Neochetina spp. (combined) (Coleoptera: Curculionidae), and Orthogalumna terebrantis Wallwork (Sarcoptiformes: Galumnidae) were recorded with notable variation in abundance between the river and dams across regions. Insecticide residues were not detected on all leaves sampled across study regions, however, nutrients were detected with nitrate ranging between oligotrophic and mesotrophic. Phosphorus was also detected, but, neither of the nutrients correlated with the occurrence and abundance of naturalized biological control agents of P. crassipes. Bioassays were conducted to measure the effect of commonly used insecticides (viz. Methomyl and Chlorpyrifos) on the survival and feeding damage of biological control agents of P. crassipes. Survival of individual insects was recorded between 0.5 and 120 hours for Megamelus scutellaris and Neochetina eichhorniae Warner (Coleoptera: Curculionidae) adults for treatments where insecticides were topically applied onto the insects or leaves were dipped into the pesticides. Concentrations below field rates, recommended and above field rates of Methomyl and Chlorpyrifos on either exposure techniques significantly reduced survival and feeding of biocontrol agents. Methomyl was more toxic compared to Chlorpyrifos and it significantly reduced the survival of M. scutellaris and N. eichhorniae. In conclusion, in this study, population abundance of biocontrol agents of P. crassipes at the Lowveld region of Mpumalanga was not influenced by pesticide drift, but, insecticides commonly used in the citrus orchards has the potential to negatively impact naturalized biological control of P. crassipes as demonstrated by the bioassays. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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The views and opinions of Rhodes University lecturers towards isiXhosa as a language of learning and teaching (LOLT) in higher education
- Authors: Nkunzi, Zintle
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424963 , vital:72197
- Description: This research sought to investigate how African languages function as a communicative tool in a university where English is the medium of instruction. The study's purpose is to provide a systematic review of research that has been carried out on language attitudes towards isiXhosa as a language of learning and teaching (LoLT) in higher education. The study reveals that South African higher education institutions such as Rhodes University mostly use English as the LoLT- a language which for most lecturers is not their first/home language but helps ease communication in a multilingual community. Rhodes University is characterised by multilingualism because the university community is made up of diversity in culture, language, and educational background of the people. Previously explored language attitude studies are based on students’ views and this study investigated RU lecturer views and opinions towards isiXhosa as a LoLT. The study focused on the importance and the need (if any) of isiXhosa in a multilingual higher education institution. The study reveal that language barriers are one of the difficulties, but academic cultural differences seem to play a crucial role that can impact on the learning and teaching outcomes. This can lead to negative experiences and the forming of stereotypical views. These views include how lecturers are and should be trained to teach mathematics, science, and academic studies in African languages. The SA higher education practices and language use (i.e., monolingual language policy) are one of the reasons that the implementation of indigenous languages in education policies in SA is fraught with difficulties due to several factors. Amongst the factors is the fact that indigenous languages are not yet fully developed as academic languages. The study further reveals that lecturers find it difficult to teach mathematical studies in isiXhosa because of lack of terminology in the language for academic purposes particularly at a tertiary level. Furthermore, existing literature highlights the importance of the use of code-switching which is a beneficial practice for lecturers in assisting their students who struggle with English as a LoLT at RU. The lecturer views towards isiXhosa as a LoLT at RU is not only on language barrier but also about the lack of development in the language use in spaces where only English is believed to be the best such as language for academics. The study also reveals an integration of Information Communication Technology in education and how language appears as a barrier. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2023
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Towards interrogating the notion of a Black aesthetic in multi-cultural Africa
- Authors: Maina, Muhunyo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425231 , vital:72221
- Description: Enbargoed. Expected release date 2025. , Thesis (MA) -- Faculty of Humanities, Fine Art, 2023
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Photodynamic therapy using morpholine substituted porphyrins in the presence of cancer specific molecules linked to graphene quantum dots
- Authors: Magaela, Ngwanabjala Bridged
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422486 , vital:71947
- Description: This thesis reports on the synthesis, characterization, photophysiochemical properties of morpholine substituted symmetrical and asymmetrical porphyrins. The synthesized porphyrins are conjugated to cancer selective biomolecules (folic acid and biotin) which are linked to nitrogen doped graphene quantum dots, as potential photosensitizers for photodynamic therapy (PDT). The symmetrical morpholine porphyrin complexes 2 (Sn(IV) 5,10,15,20 tetra-4-morpholinyl porphyrin) and 3 (Zn 5,10,15,20 tetra-4-morpholinyl porphyrin) had the same substituent but different central metals, and they were both conjugated to biotin decorated nitrogen doped graphene quantum dots (B-NGQDs), however complex 2 (Sn(IV) 5,10,15,20 tetra-4-morpholinyl porphyrin) was conjugated to B-NGQDs through an ester bond and complex 3 (Zinc 5,10,15,20 tetra-4-morpholinyl porphyrin) through 𝜋-𝜋 stacking. The effect of asymmetry was studied by comparing complex 3 (Zn 5,10,15,20 tetra-4-morpholinyl porphyrin) and complex 5 (Zn 5- bromophenyl-10-15-20-(tris-4- morpholinyl) porphyrin). Complex 5 (Zn 5- bromophenyl-10-15-20-(tris-4- morpholinyl) porphyrin) was an asymmetric porphyrin with morpholine and bromine as substituents. It was observed that asymmetry enhances singlet oxygen quantum yield and PDT activity. It was also observed that folic acid is a better targeting biomolecule when compared to biotin, and this was studied by comparing complex 3 conjugated to B-NGQDs and complex 3 conjugated to folic acid decorated nitrogen doped graphene quantum dots (FA-NGQDs). 3-FA-NGQDs had a better cellular uptake and PDT activity. , Thesis (MSc) -- Faculty of Science, Chemistry, 2023
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The development of a low-cost real- time bacterial plate culture monitoring system
- Authors: Songcata, Ntobeko
- Date: 2023-03-29
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/422437 , vital:71942
- Description: Access restricted. Access embargoed until 2025. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2023
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