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Activity of diverse chalcones against several targets: statistical analysis of a high-throughput virtual screen of a custom chalcone library

  • Authors: Sarron, Arthur F D
  • Date: 2020
  • Subjects: Acetophenone , Benzaldehyde , Ketones , Pyruvate kinase , Drug development , Aromatic compounds , Heat shock proteins
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/116028 , vital:34291
  • Description: Chalcone family molecules are well known to have therapeutic proprieties (anti-inflammatory, anti-microbial or anti-cancer, etc). However the mechanism of action in some cases is not well known. A virtual library of this family of compounds was constructed using custom scripts, based on the aldol condensation, and this library was modified further to analogues by expansion of the α,β-unsaturated ketone linker. Acetophenone and benzaldehyde derivatives which are available and purchasable were used as a base to design the chalcone virtual library. 8063 chalcones were constructed and geometrically optimized with Gaussian 09. Their physicochemical characteristics linked to the Lipinski rules were analyzed with Knime and CDK. The entire library was after docked against several targets including HIV-1 integrase, MRSA pyruvate kinase, HSP90, COX-1, COX-2, ALR2, MAOA, MAOB, acetylcholinesterase, butyrylcholinesterase and PLA2. With the exception of MAOA, which does not have a crystal structure ligand, all dockings were validated by redocking the original ligand provided by the literature. These targets are known in the literature to be inhibited by chalcone-derivatives. However, specificity of the particular known chalcone inhibitors to the particular targets is not known. To this end the performance of the generated chalcone library against the list of targets was of interest. The binding energy of ligand-protein complexes was generally good across the library. Statistical analysis including principal component analysis and hierarchical clustering analysis were made in order to investigate for any physical/chemical characteristics which might explain what chalcone features affect the binding energy of the ligand-protein complexes. The spherical polar coordinates defining the orientation of the binding poses were also calculated and used in the statistical analysis. The statistical analysis has allowed us to hypothesize the importance of these radial distances and the polar angles of key atoms in the chalcones in binding to the pyruvate kinase crystal structure. This was validated by the docking of another small library of compound models in which the α,β-unsaturated ketone chain of the chalcone was replaced by incrementally longer conjugated chains. Further studies on the chalcones themselves reveal rotameric systems in both cis and trans-configurations (which may impact binding), and also studied was the effect of Topliss-based modification and its impact of binding to HSP90. Molecular dynamics confirmed good binding of identified chalcone hits.
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  • Date Issued: 2020

Adaptive Neuro-Fuzzy Inference System modelling of surface topology in ultra-high precision diamond turning of rapidly solidified aluminium grade (RSA 443)

  • Authors: Zvikomborero, Hweju
  • Date: 2020
  • Subjects: Mechatronics Surface roughness -- Measurement
  • Language: English
  • Type: Thesis , Masters , MEng
  • Identifier: http://hdl.handle.net/10948/49441 , vital:41721
  • Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
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  • Date Issued: 2020

Addo Elephant National Park 1900 – 1955: An Environmental History of the struggle between elephants and emerging commercial farmers in the Sundays River Valley

  • Authors: Jones,Nicholas Austen Inskip
  • Date: 2020
  • Subjects: Wildlife conservation -- South Africa -- Addo National Park
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/46922 , vital:39733
  • Description: The research covers the first half of the 20th Century in the Sundays River Valley, and the relations between the elephants and the local farmers. The research includes some discussion of the implementation of new ideas to agriculture, irrigation, and colonial settlement with the interplay between the colonial farmers and the Administration. There is reference to the early politics surrounding nature conservation and the difficulties faced by farmers from wildlife and the difficulty wildlife face trying to co-exist alongside early intensive commercial agriculture.Included is the decision making process of the Colonial administration with reference to wildlife and agriculture relating to charismatic animal species.
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  • Date Issued: 2020

Addressing flux suppression, radio frequency interference, and selection of optimal solution intervals during radio interferometric calibration

  • Authors: Sob, Ulrich Armel Mbou
  • Date: 2020
  • Subjects: CubiCal (Software) , Radio -- Interference , Imaging systems in astronomy , Algorithms , Astronomical instruments -- Calibration , Astronomy -- Data processing
  • Language: English
  • Type: Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/147714 , vital:38663
  • Description: The forthcoming Square Kilometre Array is expected to provide answers to some of the most intriguing questions about our Universe. However, as it is already noticeable from MeerKAT and other precursors, the amounts of data produced by these new instruments are significantly challenging to calibrate and image. Calibration of radio interferometric data is usually biased by incomplete sky models and radio frequency interference (RFI) resulting in calibration artefacts that limit the dynamic range and image fidelity of the resulting images. One of the most noticeable of these artefacts is the formation of spurious sources which causes suppression of real emissions. Fortunately, it has been shown that calibration algorithms employing heavy-tailed likelihood functions are less susceptible to this due to their robustness against outliers. Leveraging on recent developments in the field of complex optimisation, we implement a robust calibration algorithm using a Student’s t likelihood function and Wirtinger derivatives. The new algorithm, dubbed the robust solver, is incorporated as a subroutine into the newly released calibration software package CubiCal. We perform statistical analysis on the distribution of visibilities and provide an insight into the functioning of the robust solver and describe different scenarios where it will improve calibration. We use simulations to show that the robust solver effectively reduces the amount of flux suppressed from unmodelled sources both in direction independent and direction dependent calibration. Furthermore, the robust solver is shown to successfully mitigate the effects of low-level RFI when applied to a simulated and a real VLA dataset. Finally, we demonstrate that there are close links between the amount of flux suppressed from sources, the effects of the RFI and the employed solution interval during radio interferometric calibration. Hence, we investigate the effects of solution intervals and the different factors to consider in order to select adequate solution intervals. Furthermore, we propose a practical brute force method for selecting optimal solution intervals. The proposed method is successfully applied to a VLA dataset.
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  • Date Issued: 2020

Adol-Safety: A Framework for Empowering Parents to be Aware of Social Network Threats Affecting Adolescents

  • Authors: Mjoli, Phumelela , Shibeshi, Z
  • Date: 2020
  • Subjects: Social networks Social media|
  • Language: English
  • Type: Thesis , Masters , MSc (Computer Science )
  • Identifier: http://hdl.handle.net/10353/12016 , vital:39127
  • Description: The use of social networks has grown so much that adolescents have become active members of various social networks such as Twitter, Facebook, and Instagram, etc. The gradual change in how people choose to communicate, socialize and share ideas today has influenced adolescents to an extent that they find themselves wanting to engage more on social networks than they really should due to peer pressure. Whenever a person joins social networks or browses the Internet, they by default are exposed and become vulnerable to many cyber threats. Cyber threats are driven by users that have negative intentions on the Internet or social networks. Adolescents are no exception to these cyber threats. The findings of this research reveal that threats such as cyberbullying, harassment, and online predators to name a few are often designed to abuse and affect adolescents). Therefore, this research aims to prevent such threats from prevailing by empowering parents to be aware of the threats that affect their adolescents in an online environment, which typically includes social networks. To achieve this, this research starts by investigating the cyber threats that affect adolescents and then explores ways that can be used to empower parents. A framework is developed to handle this. The framework includes strategies that parents can adopt and ways in which safety on social networks can be increased, as well as guidelines that can be followed in order to prevent cyber threats. The framework also aims to enhance a parent-child relationship that can help in preventing social network threats. Lastly, the framework is implemented as a knowledgesharing website that can be used by parents to receive and give an insight into social network threats that influence adolescents on social networks.
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  • Date Issued: 2020

African Foreign Policies: Selecting signifiers to explain agency

  • Authors: Bischoff, Paul, 1954-
  • Date: 2020
  • Subjects: Africa Foreign relations 1960- , Africa Politics and government 1960-
  • Language: English
  • Type: text , book
  • Identifier: http://hdl.handle.net/10962/161716 , vital:40657 , ISBN 9780367348281 , https://www.routledge.com/African-Foreign-Policies-Selecting-Signifiers-to-Explain-Agency/Bischoff/p/book/9780367348281
  • Description: This book explores, at a time when several powers have become serious players on the continent, aspects of African agency, past and present, by African writers on foreign policy, representative of geography, language and state size. In the past, African foreign policy has largely been considered within the context of reactions to the international or global 'external factor'. This ground-breaking book, however, looks at how foreign policy has been crafted and used in response not just to external, but also, mainly, domestic imperatives or (theoretical) signifiers. As such, it narrates individual and changing foreign policy orientations over time - and as far back as independence - with mainly African-based scholars who present their own constructs of what is a useful theoretical narrative regarding foreign policy on the continent - how theory is adapted to local circumstance or substituted for continentally based ontologies. The book therefore contends that the African experience carries valuable import for expanding general understandings of foreign policy in general. This book will be of key interest to scholars and students of Foreign Policy Analysis, Foreign Policy Studies, African International Relations/Politics/Studies, Diplomacy and more broadly to International Relations. , Introduction / Paul-Henri Bischoff -- What Next? Past and present African foreign policy concepts and practices / Paul-Henri Bischoff -- The African Union as a Foreign Policy Player: African Agency in International Cooperation / Tshepo Gwatiwa -- Unprincipled Pragmatism and Anti-Imperialist Impulses in an Interconnected World: The Zuma Presidency, 2009-2017 / Mzukisi Qobo -- Towards A Strategic Culture Approach to Understanding and Conceptualising Ethiopia's Foreign Policy Towards Israel and the Middle Eastern Arab Countries / Makonnen Tesfaye -- Nigeria's Foreign Policy and Intervention Behaviour in Africa: What Role for Agency? / Olumuyiwa Amao -- Zimbabwe and New Signifiers: Towards a cultural political economy of Foreign Policy Making / Mike Mavura -- Realist Conceptions of Kenya's Foreign Policy and Foreign Policy Behaviour: A Theoretical and Contextual Disposition / Korwa Gombe Adar and Mercy Kathambi Kaburu -- Addressing the Conceptual Void of African Small State Foreign Policy in Orthodox Theory: A Case Study of Botswana's Principled Pragmatism / Kabelo M. Mahupela -- Tunisia's Foreign Policy Towards France Before and After an Undemanding 'Revolution': A Theoretical Explanation of the An-Nahdha-led Interim Governments' Soft Policy / Ahmed Ali Salem -- Straddling Between Convergence and Divergence: A Constructivist's View of Malawi's Foreign Policy in Post-independence Africa / Eugenio Njoloma -- Strategies of a Small State Between Realism and Liberalism: Sixty Years of Guinea's Diplomacy and Foreign Policy (1958-2018) / Issaka K. Souaré -- Rethinking SADC's Collective Policymaking Processes on External Relations and Non-state Participation for Region-building / Cecilia Lwiindi Nedziwe -- Towards an Understanding of the Interplay Between Ghana's Foreign and Defence Policies / Kwesi Aning and Kwaku Danso -- Conclusion / Paul-Henri Bischoff
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  • Date Issued: 2020

Afromelampsalta, a new genus, a new species, and five new combinations of African cicadettine cicadas (Hemiptera: Cicadidae: Cicadettinae):

  • Authors: Sanborn, Allen F , Villet, Martin H
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/140680 , vital:37909
  • Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
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  • Date Issued: 2020

Age is nothing but a number: Ben 10s, sugar mummies, and the South African gender order in the Daily Sun’s Facebook page

  • Authors: Mlangeni, Ntombikayise Lina
  • Date: 2020
  • Subjects: May-December romances -- South Africa , Women in mass media , Men in mass media , Sex role in mass media , Masculinity in mass media , Feminism and mass media , Critical discourse analysis , Unemployment -- Social aspects -- South Africa , Daily Sun (South Africa) , Ben 10
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10962/167077 , vital:41435
  • Description: This thesis examines how meanings of masculinity and femininity are negotiated by South Africans on a social media platform linked to a popular local tabloid newspaper. In particular it explores conversations surrounding the Ben 10 phenomenon on the Daily Sun’s Facebook page. A Ben 10 is commonly understood as a young man who enters into a sexual relationship with an older woman, mostly in township settings, and readers engage vociferously over the meanings of such relationships. Using a constructivist understanding of gender, a thematic analysis is used to examine the Facebook comments on the Daily Sun’s most popular Ben 10 stories. South Africa’s constitution promotes the right to gender equality and freedom, which contributes to the normalisation of sex in public conversations and political debate. However, with high levels of unemployment and poverty in South Africa, the narrative of masculine success through work remains relatively unattainable. This tension between the narrative of male-bread winner through work and the reality of South Africa’s poverty and unemployment has been referred to as the crisis of masculinity. This thesis will argue that tabloids can play a strong political role by providing an alternative public sphere and that they can also assist their readers in coping with life in a democratic society by creating an imagined community of people sharing common experiences.
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  • Date Issued: 2020

Age of squid Loligo reynaudii d’Orbigny, 1845, and its possible use to test effectiveness of the closed season in protecting this resource

  • Authors: Mwanangombe, Collette Habani
  • Date: 2020
  • Subjects: Loliginidae -- Spawning -- South Africa , Loliginidae -- Age determination , Loligo fisheries -- South Africa , Fishery management -- South Africa , Otoliths , Loliginidae – Eggs -- Incubation , Loliginidae – Growth , Fish stock assessment -- South Africa , Recruitment (Population biology) -- South Africa , Loligo reynaudii d’Orbigny
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/144333 , vital:38336
  • Description: This study presents age distributions representing populations of adult Loligo reynaudii, together with the results of spawning and commercial catches to assist in understanding the beneficial role of the closed season. The results were based on 791 samples collected during three closed seasons (November: 2003, 2004 and 2005) and out of closed season during April/May 2005. Age and predicted growth were examined by counting daily rings on statolith microstructures. The age in days after hatching ranged from 168 to 484 days (71-425 mm) in males and from 125 to 478 days (83-263 mm) in females. Average age at spawning was found to be 323 days in males and 316 days in females. Population estimates of growth rates were best described by a linear growth model which revealed that males grew faster than females in length as they grew older with growth rate ranging between 0.63 to 0.83 mm per day for males and between 0.22 to 0.32 mm per day for females. Back-calculated hatch dates and later egg-laying events for parental populations were determined. Results from back calculated egg laying dates (presented as percentage of frequency of all laying dates) indicated a highest total of 36%, 39% and 15% of eggs from all samples were laid during the closed season and nine days after the closed season during year 2003, 2004 and 2005 respectively. Monthly commercial total catches (2002-2005) showed an increase from November soon after the fishery resumed, up until the month of January. Daily catches were highest in November (up to 290 tonnes) relative to the daily catches observed in December and January in all the years. Results led to the conclusion that the closed season (25 October to 22 November) is beneficial for both the chokka resource and the fishery. This is because: a) there is time for enough spawning biomass to accumulate, which subsequently results in high catches (good fishery), in the current year, best immediately after season opens in November; b) there is a link in the results between egg laying dates in the period of closed season and immediately afterwards, and the magnitude of catches in last nine days of November.
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  • Date Issued: 2020

Agents sans frontiers: cross-border aquatic weed biological control in the rivers of southern Mozambique

  • Authors: Langa, Sílvia da Fátima , Hill, Martin P , Compton, Stephen G
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/148998 , vital:38794 , DOI: 10.2989/16085914.2020.1749551
  • Description: Biological control is an effective ways of controlling aquatic plants, especially in South Africa. Release of biological control agents has been limited to Mozambique, where water hyacinth (Eichhornia crassipes (Mart.) Solms-Laubach (Pontederiaceae)), water lettuce (Pistia stratiotes L. (Araceae)), red water ferns (Azolla spp. (Azollaceae)) and salvinia (Salvinia molesta DS Mitch. (Salviniaceae)) are significant weeds in the south of the country. In 2009, we assessed the status of these weeds in seven rivers across southern Mozambique and recorded whether any biocontrol agents were present.
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  • Date Issued: 2020

Aileen wuornos : a psychobiographical study

  • Authors: Fakude, Shuanize Xiluva
  • Date: 2020
  • Subjects: Women serial murderers
  • Language: English
  • Type: Thesis , Masters , MA
  • Identifier: http://hdl.handle.net/10948/50789 , vital:42700
  • Description: A psychobiographical study is an exploration of a unique individual’s entire lived life through a psychological lens. The aim of the study was to explore and describe the personality development of Aileen Wuornos within her socio-historical context by applying Erikson’s Theory of Psychosocial Development. Aileen Carol Wuornos was an American serial killer who murdered seven men in Florida between 1989 and 1990 by shooting them at point blank range. Wuornos’s life was marked by a difficult formative environment, maternal abandonment, and adoption by her grandparents. Wuornos continued to experience physical, emotional and sexual abuse at the hands of family members, friends and the community. Wuornos lived her life focusing on survival, and started to engage with petty crime and prostitution to do so. Her patterns escalated to include more serious criminal behaviour, culminating in serial murder. Wuornos was selected for this study using nonpropability purposive sampling. She was selected based on the researcher’s curiosity of her life events and experiences that led her to commit serial murders. Data was collected through a variety of primary and secondary sources on Wuornos and it was analysed using Miles and Huberman’s three steps process of data analysis, which includes data reduction, data display, and conclusion drawing and verification. The findings of this study indicate that Wuornos experiences severe difficulties in renegotiating the seven stages proposed by Erikson’s Theory of Psychosocial Development, and all the ego strengths that she developed were seriously delayed.
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  • Date Issued: 2020

Alignment in the orientation of LOFAR radio sources:

  • Authors: Osinga, E , Miley, G K , van Weeren, R J , Shimwell, T W , Duncan, K J , Hardcastle, M J , Mechev, A P , Röttgering, H J A , Tasse, C , Williams, W L
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/163452 , vital:41039 , https://doi.org/10.1051/0004-6361/202037680
  • Description: Various studies have laid claim to finding an alignment of the polarization vectors or radio jets of active galactic nuclei over large distances, but these results have proven controversial and so far, there is no clear explanation for this observed alignment. To investigate this case further, we tested the hypothesis that the position angles of radio galaxies are randomly oriented in the sky by using data from the Low-Frequency Array (LOFAR) Two-metre Sky Survey (LoTSS). A sample of 7555 double-lobed radio galaxies was extracted from the list of 318 520 radio sources in the first data release of LoTSS at 150 MHz. We performed statistical tests for uniformity of the two-dimensional (2D) orientations for the complete 7555 source sample. We also tested the orientation uniformity in three dimensions (3D) for the 4212 source sub-sample with photometric or spectroscopic redshifts.
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  • Date Issued: 2020

Alternative pine species/hybrids for the Cape timber growing regions of South Africa

  • Authors: Van der Hoef, André
  • Date: 2020
  • Subjects: Species -- South Africa
  • Language: English
  • Type: Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10948/47613 , vital:40258
  • Description: Pinus radiata has been the preferred commercial sawtimber species for the Cape forestry region for many years. Since the introduction of Fusarium circinatum, and the susceptibility of P. radiata to this disease, the sustainable production of this pine species for the Cape has been negatively impacted due to poor survival in the nursery and in field plantings. For this reason, a number of additional pine species and hybrids have been established in the Cape region of South Africa since 2006 to identify taxa that would perform as well as or better than P. radiata. Three research trials were implemented on contrasting sites that contained eight common species/hybrids treatments that included P. elliottii, P. elliottii x P. caribaea, P. radiata, P. patula x P. greggii var. australis, P. patula x P. oocarpa, P. patula x P. tecunumanii (HE), P. patula x P. tecunumanii (LE) and P. tecunumanii (HE) x P. oocarpa were established at Witelsbos, Kruisfontein and Garcia across diverse soil types, drainage and climate conditions in the Cape. Survival, growth data and tree morphology (forking, foxtails, broken tops and stem form) were assessed at five years of age and individual tree volume was calculated. Five year results indicate that on the waterlogged site at Witelsbos P. elliottii and its hybrid with P. caribaea was best in terms of productivity, at the dry site of Garcia, P. taeda and P. elliottii demonstrated promise, and at Kruisfontein, the most fertile site, P. elliottii x P. caribaea, P. patula x P. tecunumanii (LE) and P. maximinoi were found to be promising alternatives to P. radiata. Wood properties were assessed at Kruisfontein at six-years of age. Basic density and Modulus of Elasticity (MOE) were found to be significantly different for the various species/hybrids. Pinus patula x P. tecunumanii (LE), P. patula x P. greggii (S), P. maximinoi and P. patula x P. tecunumanii (HE) were all significantly better than P. radiata, which would suggest that these taxa would have similar or superior wood strength over P. radiata, the preferred sawtimber species for the Cape region. Only P. tecunumanii (HE) x P. oocarpa had a higher basic density than P. radiata, but not significantly different. Species that had similar basic density were P. patula x P. greggii (S), P. taeda and P. tecunumanii (LE) x P. caribaea. Although P. elliottii x P. caribaea had the highest volume at Witelsbos and Kruisfontein, the timber qualities were the worst, suggesting that some breeding is needed to improve this hybrid to be an acceptable sawtimber species. From this study, several potential alternative species/hybrids have been identified that are tolerant to the F. circinatum pathogen and have acceptable growth and wood properties, compared to P. radiata.
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  • Date Issued: 2020

AMBER force field parameters for the Zn (II) ions of the tunneling-fold enzymes GTP cyclohydrolase I and 6-pyruvoyl tetrahydropterin synthase

  • Authors: Khairallah, Afrah , Tastan Bishop, Ozlem , Moses, Vuyani
  • Date: 2020
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/429360 , vital:72604 , xlink:href="https://doi.org/10.1080/07391102.2020.1796800"
  • Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase. Both GCH1 and PTPS enzymes contain Zn2+ ions in their active sites, and to accurately study their dynamic behaviors using all-atom molecular dynamics (MD) simulations, appropriate parameters that can describe their metal sites should be developed and validated. In this study, force field parameters of the GCH1 and PTPS metal centers were generated using quantum mechanics (QM) calculations and then validated through MD simulations to ensure their accuracy in describing and maintaining the Zn2+ ion coordination environment. The derived force field parameters will provide accurate and reliable MD simulations involving these two enzymes for future in-silico identification of drug candidates against the GCH1 and PTPS enzymes.
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  • Date Issued: 2020

AMBER force field parameters for the Zn (II) ions of the tunneling-fold enzymes GTP cyclohydrolase I and 6-pyruvoyl tetrahydropterin synthase:

  • Authors: Khairallah, Afrah , Tastan Bishop, Özlem , Moses, Vuyani
  • Date: 2020
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/163068 , vital:41009 , DOI: 10.1080/07391102.2020.1796800
  • Description: The folate biosynthesis pathway is an essential pathway for cell growth and survival. Folate derivatives serve as a source of the one-carbon units in several intracellular metabolic reactions. Rapidly dividing cells rely heavily on the availability of folate derivatives for their proliferation. As a result, drugs targeting this pathway have shown to be effective against tumor cells and pathogens, but drug resistance against the available antifolate drugs emerged quickly. Therefore, there is a need to develop new treatment strategies and identify alternative metabolic targets. The two de novo folate biosynthesis pathway enzymes, GTP cyclohydrolase I (GCH1) and 6-pyruvoyl tetrahydropterin synthase (PTPS), can provide an alternative strategy to overcome the drug resistance that emerged in the two primary targeted enzymes dihydrofolate reductase and dihydropteroate synthase.
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  • Date Issued: 2020

An analysis of carbon tax and other environmental levies: a South African and international perspective

  • Authors: Vuzane, Rolihlahla
  • Date: 2020
  • Subjects: Carbon taxes , Carbon taxes -- South Africa , Environmental impact charges , Environmental impact charges -- South Africa , Taxation -- Environmental aspects , Taxation -- Environmental aspects -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MCom
  • Identifier: http://hdl.handle.net/10962/167676 , vital:41502
  • Description: As a “Non-Annex 1” country, there was no obligation for South Africa to reduce its carbon emissions. South Africa undertook, of its own volition, to take measures to reduce 34% of the carbon monoxide emissions by 2020 and 42% by 2025 respectively. In response, South Africa promulgated the Carbon Tax Act, No. 15 of 2019. This study seeks to answer the question: After analysing the range of environmental taxes levied in the Scandinavian countries (Denmark, Finland, Norway and Sweden) and in South Africa, are there lessons that can be learnt for South Africa? In answering this question, the carbon tax structure in South Africa and in selected Scandinavian countries is analysed, together with existing environmental taxes and the related policies, using a literature study. What is evident from the Scandinavian countries studied, is that environmental taxes have distributional effects and are effective in reducing carbon emissions. The major result of the study was that the real weakness of the newly introduced Carbon Tax Act is that in both in the first and second phase of its implementation, the carbon tax rate is too low to send an appropriate signal to the market and would not have the desired outcome. In addition, there are currently no guidelines that inform the revenue recycling technique to ensure transparency of revenue usage, improved energy management, or how the Carbon Tax Act will promote environmental quality. A major concern is that carbon tax revenue will not be ring-fenced. Given that South Africa is a developing country and depends mainly on non-renewable energy, it is inevitable that most of its sectors will be subject to the carbon tax. A plausible approach is the one that promotes the idea of taxing those more heavily that contribute most to environmental degradation and are highly energy concentrated, to promote parity between the harm to the environment and the taxes levied to redress the harm.
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  • Date Issued: 2020

An analysis of crime trends at University of Fort Hare, Alice campus: Ten years (2008-2018) projection case studies

  • Authors: Giyama, Mlungisi https://orcid.org/0000-0002-4024-9447
  • Date: 2020
  • Subjects: Criminal statistics , Victims of crimes surveys
  • Language: English
  • Type: Master's theses , text
  • Identifier: http://hdl.handle.net/10353/28584 , vital:74447
  • Description: This research has concerted on the trend of crimes committed at University Fort Hare over past ten years. The previous conducted researches show several forms of crimes committed at different higher learning institutions and some crime are even cited happening in South Africa. The problem is Incompetence of University of Fort Hare security guards, which are responsible to prevent the occurrence of crime at the Alice campus. The university have scarcity of programmes that intends to inform students and staff members on how to protect themselves when there is crime threat. University of Fort Hare has unlimited access by community members. The knowledge gap on crimes committed at higher leaning is unexplained psychological such as depression and stress experienced by perpetrators. Secondly, there is lack of studies focused on the discussion about importance of criminal background check of prospective students. The unavailability of electronics that scans dangerous weapons such as knife (okapi) result to crimes such as murder at University of Fort Hare. The problem of abusing alcohol and other drugs by students result to rapes when students are drunk or high. The study aims to evaluate the trend in crimes that occurred from July 2008 to August 2018 at the University of Fort Hare Alice Campus. The objective is to find out types of crimes that occur quarterly at the University of Fort Hare Alice Campus. To discover the perception of selected staff members and students about the safety on campus and to find strategies introduced by the university to address crimes that are committed at University of Fort Hare Alice campus. The study has adopted qualitative research method and exploratory research design. The questions to be asked include what types of crimes occur at University of Fort Hare Alice Campus and how is the perception of selected staff members and students about the safety on campus? The researcher found out that crimes occurring at the University of Fort Hare Alice Campus has changed to new forms of crimes such as murder, looting of shops, slaughtering cattle, deformation of character on social media, bribery for academic admission, arson of buildings, stealing of university property, rapes and sexual assaults meanwhile these crimes were not prominent before 2008. The researcher discovered that students are the ones mostly affected by crimes that happened at University of Fort Hare (UFH) Alice campus in 2015, 2016 and 2018 thereafter followed staff members. Most people who are victims of crimes at University of Fort Hare (UFH) Alice campus arrived between 2014 and 2016. The study indicates that fewer security officers and lack of security equipment such as communicating radios cause crimes at University of Fort Hare (UFH) Alice campus. Cases reported to the security office takes a long time to conclude. Dark parts at the campus are found to cause some of crimes at the University of Fort Hare Alice campus. The significant of conducting this study, will help University of Fort Hare develop better policies regarding crimes on campus. The researcher also wanted to support the consistency of trying to find out a solution for university crime. It is recommended that University of Fort Hare management needs to hire more guards to make sure that each residence and building has a guard. During events at Alice campus that includes people from outside, there must be police and event’s organisers need to present security plan when they are requesting university facilities to ensure the safeness of staff members and students. , Thesis (MSoc) -- Faculty of Social Sciences and Humanities, 2020
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  • Date Issued: 2020

An analysis of how leadership has shaped the culture of customer centricity in the branch of a bank

  • Authors: Mali, Mandisa
  • Date: 2020
  • Subjects: Banks and banking -- Customer services , Banks and banking -- Customer services -- South Africa -- Case studies , Customer relations -- Management , Customer relations -- Management -- South Africa -- Case studies , Relationship banking -- South Africa -- Case studies , Bank management -- South Africa -- Case studies
  • Language: English
  • Type: Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/171852 , vital:42132
  • Description: Financial institutions are faced with increasing competition as there has been an increase in new entrants in the industry, therefore a battle of market share in banking is in progress. Digitization is fast changing how customers perceive value, customers have become spoilt for choice and thus banks have to implement strategies that will help them to increase their market share by keeping the customers they currently have and strategies that help them to acquire more customers. A strategy on its own will not support organizational goals, if it is not adopted by the executers – the employees on the ground. It is important for leaders to support the strategic goals of an organization by ensuring that the goals become a culture, a way of doing things in that organization. This study is an analysis of how leadership shaped a culture of customer centricity in the branch of a bank. The objectives of the study were to: (1) To describe the culture of customer centricity that was cultivated by the branch manager; (2) To analyse what the leader pays attention to, measures and controls on a regular basis, in support of a culture of customer centricity; (3) To analyse how the leader conducts deliberate role modelling, teaching and coaching in support of a culture of customer centricity; (4) To analyse whether - and if so how - the quality of the dyadic relations between the leader and her followers enables or disables the effect of cultural mechanisms on the culture of customer centricity; and (5) To analyse how the leader built high quality relations with her followers The study took the form of a case study of a branch of a bank, where nine universal bankers and their former leader were interviewed. The data were then analysed using a deductive thematic analysis. The findings met all objectives of the study and the findings supported the propositions. The findings also discovered that reward and recognition contributed to the shaping of a culture of customer centricity. In conclusion the limitations and delimitations of the study are acknowledged, and recommendations are made. The study contributes towards the Social Exchange Theory (SET) and demonstrates how high-quality leader member exchange (LMX) relations can be developed. Several recommendations are made for further studies on factors shaping a culture of customer centricity, and implications for management are considered.
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  • Date Issued: 2020

An analysis of how visualisation capabilities in dynamic geometric software develop meaning-making of mathematical concepts in selected Grade 11 learners

  • Authors: Mavani, Deepack Pravin
  • Date: 2020
  • Subjects: Mathematics -- Study and teaching (Secondary) -- South Africa , Mathematics -- Computer programs , Mathematics -- Study and teaching (Secondary) -- South Africa -- Case studies , Mathematics -- Study and teaching -- Activity programs , Educational technology , Visualization
  • Language: English
  • Type: text , Thesis , Doctoral , PhD
  • Identifier: http://hdl.handle.net/10962/143213 , vital:38211
  • Description: Visualisation plays a central role in developing mathematical ideas because it can be used to make these ideas explicit and visible, and thus has the potential to advance understanding. This study centred around the GeoGebra Literacy Initiative Project (GLIP), a teacher development initiative in Mthatha that aimed to grow and develop appropriate Information and Communication Technology (ICT) skills in teachers, to harness the teaching and learning potential of GeoGebra. GeoGebra is a dynamic geometric software package that is very interactive and makes use of powerful features to create images which can be moved around the computer screen for mathematical exploration. This research project was located within GLIP and analysed how GeoGebra applets develop conceptual and procedural understanding in selected Grade 11 learners. One aspect of GLIP was for teachers to use GeoGebra applets that they had developed themselves and implemented in their classrooms in pre-determined cycles that were aligned to the curriculum. My study specifically focused on how the selected learners made use of these applets and explored how learning had taken place in terms of developing mathematical meaning-making. This interpretive research study was designed as a case study. The case was a cohort of selected Grade 11 learners who had been taught by GLIP teachers, and my unit of analysis was the learners’ interaction with the applets. A screen capturing software package was used to capture learners’ interactions with the GeoGebra. My data consisted mainly of recorded observations and interviews. An analytical framework derived from the works of Kilpatrick, Swafford, and Findell (2001) and Carter et al. (2009) guided and informed the data analysis of the learners’ activities with the GeoGebra. The theoretical orientation of this study was constructivist learning. An in-depth analysis and detailed descriptions of the participants’ interactions enabled me to gain a comprehensive understanding of their meaning-making processes in a technological classroom context. An analysis across the participants identified distinguishable patterns or differences in the development of the learners’ mathematical proficiency and making sense of mathematical ideas. The research argued that technology enabled visualisation was a powerful tool to not only enrich mathematically activities, but to also enrich conceptual and procedural understanding. The findings recognised that exploration of, or manipulation on mathematical objects in GeoGebra was a key activity in the participants’ meaning-making process. It also enabled learners to offer self-proclaimed theories
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  • Date Issued: 2020

An analysis of indicators disclosed in the integrated annual reports of selected South African retailers

  • Authors: Blignaut, Anna Cornelia
  • Date: 2020
  • Subjects: Financial statements -- South Africa -- Case studies , Retail trade -- South Africa
  • Language: English
  • Type: text , Thesis , Masters , MBA
  • Identifier: http://hdl.handle.net/10962/140859 , vital:37924
  • Description: This study aimed to analyse the indicators disclosed in the Integrated Annual Reports (IARs) of selected South African retailers. This was firstly done by identifying the six capital and governance indicators retailers report on in order to analyse the commonalities and differences between them, secondly by identifying and assessing evidence of integrated thinking and lastly by making recommendations for optimal retail sector reporting. IARs from Pick n Pay Stores Ltd, Shoprite Holdings Ltd, Spar Group Ltd and Woolworths Holdings Ltd were analysed using content analysis. The results found noteworthy differences in IAR composition in terms of report length and the sections retailers devoted more or less of their report to. Governance and Remuneration indicator disclosure did not allow for broad comparison among all four retailers. In terms of indicator disclosure few indicators were disclosed by all retailers, whilst many were only disclosed by one retailer. Disclosures related to all six capitals were found, yet some indicators were disclosed excessively. Paradoxically, insufficient disclosure of indicators that are easily measurable and low levels of negative or unfavourable indicator disclosure was also apparent in this study. The comparability of indicators was influenced by the aggregation and disaggregation of indicators as well as the lack of consistency in the terminology used in IARs. Indicator disclosure also revealed several trends in the South African retail industry. This research identified the following six themes related to integrated thinking in the sample IARs. Retailers understand the connection between capitals, express consideration for multiple stakeholders and appreciate the context in which they operate, to some extent. Retailers were also found to have different interpretations of sustainability as part of their strategy and risk management whilst the completeness and consistency of information disclosed and retailers’ conceptualisation of value-added in IAR has not yet developed to the same extent across the retail industry. This study finally makes recommendations that may be used for optimal retail sector reporting with regards to the integrated reporting process as well as the integrated report itself. Addressing the former it is recommended that: integrated reporting be viewed as a means to build an internal understanding of their sustainability practices; integrated thinking be included as part of their strategic planning process; all capitals be considered in decision making; communication be established with others in the retail industry and that retailers engage with the IIRC on integrated reporting issues. In terms of the IAR itself, it is recommended that retailers ensure consistency in the terminology used and that the disaggregation of indicators is done in a consistent way. Retailers should include a balance of positive and negative disclosures as well as context-based indicators and seek assurance of the social, environmental and ethical information in their IARs. Finally, retailers need to set measurable sustainability performance targets and link them to specific performance indicators. The results of this study are not without limitations. The identification and categorisation of an indicator was largely based on the researcher’s own judgement in the content analysis process and can be highlighted as the main limitation of this research.
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  • Date Issued: 2020
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