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Super-light verbs in Afrikaans
(Stellenbosch : Stellenbosch University, 2024-12) van Heerden, Lara
This thesis sets out to provide an account of super-light verbs in Afrikaans. While light verbs can be defined as a group of grammatical verbs that are semantically bleached, which means that they have lost some of their lexical content, super-light verbs are argued to be a covert form of a light verb. Based on Van Riemsdijk’s (2002) analysis of constructions with omissible motion verbs, and on Biberauer and Oosthuizen’s (2011) observations regarding omissible lexical verbs in Afrikaans, a description of two super-light verbs in Afrikaans is provided. Specifically, this thesis examines instances where the verbs gaan (“go”) and maak (“make”) in Afrikaans are ostensibly absent. This thesis is situated within a broad Minimalist Syntax framework, and as such, the core architecture and assumptions of Minimalism are first discussed, followed by a discussion of light verbs within Minimalist Syntax and of light verbs in the traditional (semantic) sense (Jespersen 1954-1958). This discussion includes an examination of the concept of silent elements, in general, and silent verbs, in particular, which Van Riemsdijk (2002) characterises as super-light verbs. Thereafter, a description of Afrikaans grammar, with a focus on Afrikaans verbs and verb clusters, is given. It is against this background that super-light verbs in Afrikaans are described. The environments in Afrikaans in which super-light verbs, namely the motion verb GAAN and the causative verb MAAK are licensed are illustrated.
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The effect of thiamine, biotin, and pyridoxine on the interaction dynamics of wine yeast consortia
(Stellenbosch : Stellenbosch University, 2024-12) van Goeverden, Hannah Isabel; Bauer, Florian; Divol, Benoit; Conacher, Cleo; Stellenbosch University. Faculty of AgriSciences. Dept. of Viticulture and Oenology.
Yeasts are the main driving force behind wine fermentation, and many species are at play in this ecosystem. Non-Saccharomyces yeasts are more abundant in the beginning of the fermentation process, but as fermentations continue, Saccharomyces cerevisiae dominates. S. cerevisiae is well adapted to the harsh fermentation environment and. Adaptations include resistance to general abiotic and biotic fermentation stresses. During fermentation, many microbial species co-exist, and ecological interactions occur. Despite the fact that interactions between yeast-yeast interactions are central to determining wine fermentation outcomes, the mechanisms that mediate these interactions are currently not well understood. Previous studies focused on the transcriptomic responses of S. cerevisiae and non-Saccharomyces species in mixed-species fermentations and have highlighted impacts on biotin-linked carbohydrate metabolic processes and the thiamine biosynthesis pathway, with pyridoxine known to play a role in thiamine synthesis. Vitamins fulfil various functions in yeast metabolism. Thiamine acts as a co-factor in various metabolic pathways, such as the tricarboxylic acid cycle, biotin plays a role in carbohydrate degradation, and pyridoxine acts as a cofactor for enzymes in amino acid metabolism. Past research has focussed on the yeast vitaminic requirements but not much is known about their role in yeast interactions. The aim of this project was, therefore, to determine the role that biotin, pyridoxine, and thiamine play in the interactions between three keystone wine yeast species, S. cerevisiae, Lachancea thermotolerans, and Torulaspora delbrueckii. We evaluated the effects of varied extracellular vitamin concentrations on the growth and fermentation dynamics of synthetic wine-associated yeast consortia in monoculture, in species pairs, and in three-species consortia. Yeast species were co-cultured in Synthetic Grape Must (SGM) in both 6-well plates and 1-L Erlenmeyer flasks, with varying vitamin concentrations to assess the impact on species interactions and growth, monitored through flow cytometry. The results showed that in the absence of exogenous thiamine, T. delbrueckii competed more closely with S. cerevisiae. Both non-Saccharomyces species exhibited significantly reduced growth without exogenous biotin, though this inhibition was mitigated in the presence of S. cerevisiae. Both of these observations were consistent across the small- and large-scale fermentations. S. cerevisiae grew significantly less in monoculture without exogenous pyridoxine, which was not observed in co-culture, in the small-scale fermentations. However, in the large-scale fermentations S. cerevisiae was unaffected by pyridoxine concentration in monoculture, but the absence of pyridoxine greatly stunted its growth in co-culture. This observation likely highlights the impact different oxygen levels and nutrient availability. The findings show that extracellular vitamin concentrations significantly influence yeast growth, but that the impact is dependent on the combination of species, revealing potential mechanisms of indirect interaction in these yeasts.
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Pre- and Post-1994 Afrikaans Cabaret: Transitions, Tensions and Tropes
(Stellenbosch : Stellenbosch University, 2024-12) van Dyk, Nadine; Venter, Carina; Bredekamp, Leonore; Stellenbosch University. Faculty of Arts and Social Sciences. Dept. of Music.
This thesis investigates the trajectory of Afrikaans cabaret within the transformative sociopolitical landscape of post-1994 South Africa. This study is anchored in the pivotal political transition of 1994 and examines the shifts in thematic content and cultural significance of Afrikaans cabaret. By conducting a comparative analysis of seminal works from both the pre- and post-1994 eras, the research delineates the ways in which the genre has adapted to South Africa’s new democratic context. The investigation is grounded in a qualitative methodology that integrates archival research, close textual analysis, and semi-structured interviews with prominent cabaret artists and writers. The key themes that are explored include identity politics, the manifestation of the outsider, and the enduring role of cabaret as a medium for social and political critique. This study contributes to a deeper understanding of how Afrikaans cabaret has negotiated its role in a redefined sociopolitical milieu, highlighting its ongoing relevance and adaptability in reflecting and shaping public discourse in South Africa.
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A tness landscape-integrated metaheuristic selection & con guration framework for binary programming problems
(Stellenbosch : Stellenbosch University, 2024-12) van der Westhuyzen, Nathan Jan; van Vuuren, J. H.; Colmant, A.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.
The research field of optimisation has witnessed a surge in the number of metaheuristic solution methodologies available in the literature since the 1970s. As a result, analysts are faced with the challenging task of having to select a metaheuristic from this wide range of approximate optimisation techniques that is best suited to each optimisation problem instance considered. This selection problem is made more difficult by the phenomenon of performance complementarity, according to which no algorithm typically dominates all other algorithms for all optimisation problem instances. Instead, different algorithms perform better in respect of different types of optimisation problem instances. Moreover, even a single metaheuristic may perform differently in respect of solving the same optimisation problem instance if it is configured differently and/or assigned different hyperparameter values. The difficulty of choosing an appropriate metaheuristic (which is properly configured) calls for the development of an automated algorithm selection framework capable of decision support in aid of these selection decisions. A metaheuristic selection and configuration framework is therefore proposed in this dissertation for reducing the effects of performance complementarity by integrating solutions to the problems of algorithm selection and algorithm configuration in a simple and efficient manner within the application context of binary programming. This framework operates in two phases — an offline phase and an online phase. The offline phase takes as input a set of optimisation problem instances and a user-specified algorithm portfolio, and guides the user through the process of constructing a comprehensive and coherent meta-learning database. Building on the output of the offline phase, the online phase is tailored to take as input unseen binary programming problem instances and produce as output valuable metaheuristic design decision support for these instances. The operational phases of the framework are executed asynchronously and iteratively, in alternating fashion, with the offline phase initially preceding the online phase. The offline phase may be re-executed to include information on new, unseen optimisation problem instances in a batch-wise fashion with a view to enhance the representativeness of the meta- learning database over time. The offline phase is the computational foundation of the framework, while its online phase is the consulting house built upon that computational foundation. The framework is verified in the context of four classical binary programming problem classes. This verification process is performed at the framework component level (that is, each component is implemented and verified individually). Inter-component interactions are also meticulously examined in order to verify the correct working of the framework implementation as an integrated system. The working of the framework is finally demonstrated in the context of a real world-inspired case study conducted in collaboration with an industry partner attached to the dissertation. In this context, the verified framework is tested against a completely new binary programming problem class, allowing for an evaluation of the framework’s flexibility and adaptability, as well as its performance in respect of a novel real-world optimisation problem class.
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Assembly and Annotation of the genome of the sea urchin Tripneustes gratilla
(Stellenbosch : Stellenbosch University, 2024-12) van der Westhuizen, Hester Christina; Rhode, Clint; Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics.
The sea urchin, Tripneustes gratilla, is considered a culinary delicacy. This species is currently being considered as a candidate for aquaculture in South Africa. Having an annotated genome for T. gratilla will be advantageous for the improvement of commercially important traits. The aim of this study was to assemble and annotate a draft genome for T. gratilla. Four individuals were sequenced - two using Ion Torrent (M1 and F2) and two using Illumina (M10 and U14). The assemblies were created using both de novo and reference-based approaches. The assembly created using the F2 Ion Torrent reads mapped to the M10 Illumina assembly had the best quality overall. Once polished, this genome had a GC content of 35.29%, a total length of 772.9 Mb, and a N50 value of 10 926. BUSCO scores were 46.3% Complete, 0.9% Duplicated, 38.3% Fragmented, and 14.5% Missing BUSCOs. The masked genome was annotated with Braker and after filtering, 33 204 genes were identified. A genome comparison was performed using the annotated genomes of three other sea urchin species: Lytechinus variegatus, Lytechinus pictus, and Strongylocentrotus purpuratus. OrthoFinder and OrthoVenn identified the numbers of orthologues shared by and unique to the four species. These orthologues along with the species tree created with OrthoFinder found that L. pictus, L. variegatus, and S. purpuratus were more closely related to each other than any of them were to T. gratilla and that L. variegatus was the least closely related to T. gratilla. The orthologues were used to run gene enrichment analyses using topGO. OrthoFinder identified the 577 single copy orthologues (SCOs) shared by the species. KaKs Calculator was used to determine the number of SCOs that are under positive selection. Pairwise comparisons detected 10, 8, and 18 SCOs in T. gratilla with L. variegatus, L. pictus, and S. purpuratus respectively that were under positive selection with p<0.05. Five of the genes, COPG2, TBC1D20, FANK1, ASPM, and PAGM were found to overlap between the comparative sets. Four of these genes (TBC1D20, FANK1, ASPM, PAGM) play a role in testes and spermatogenesis and TBC1D20 has been associated with viral activity.