Showing items 1 - 20 of 392

Your selections:

5-Fu inclusion complex capped gold nanoparticles for breast cancer therapy

  • Authors: Lakkakula, Jaya R , Krause, Rui W M , Divakaran, Deepika , Barage, Sagar , Srivastava, Rohit
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/191713 , vital:45150 , xlink:href="https://doi.org/10.1016/j.molliq.2021.117262"
  • Description: We have attempted to prolong the circulation time and increase the solubility of 5-Fluorouracil by complexing it with cyclodextrin and then further conjugating onto the gold nanoparticle to form 5Fu ICAu. The 1H NMR and molecular docking studies suggested that 5-Fu was included within the 2HP-β-CD cavity and H-5 proton probably serves as the binding site for stabilization of the inclusion complex. The 5Fu-ICAu showed higher cell inhibition rate when studied on MDA-MB-231 and MCF-7 breast cancer cell lines due to the enhanced permeability and retention (EPR) effect by allowing the selective accumulation of nanoparticles at tumor site. This unique system can serve as a novel nanocarrier for delivery of hydrophobic drugs.
  • Full Text:
  • Date Issued: 2021

A case for ethical frameworks to enhance mobile government implementation at South African municipalities

  • Authors: Makwembere, Sandra , Garidzira, Rufaro
  • Date: 2021
  • Subjects: Government Ethics Technology and state Article
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/7170 , vital:53081 , xlink:href="https://doi.org/10.4102/td.v17i1.826"
  • Description: Interest in mobile government (m-government) is growing globally. Mobile government refers to the use of wireless and mobile technologies to deliver services to citizens, businesses, employees and other government entities. Presently, technological advancements take place despite questions on whether the existing policy and regulatory frameworks are suitable to regulate the effects of m-government. With m-government, municipal operations take place in virtual spaces where the consequences of such operations are still largely unknown and the frameworks that are apt to minimise any long-term effects on society are yet to be defined. This conceptual article suggests that ethical frameworks should be encouraged as part of mobile government implementation in municipalities to encourage reflective municipal practices and to improve judgement and behaviour in m-government decision-making. It contributes to debates on approaches to comprehensively support and guide mobile government towards positive municipal service delivery outcomes. Keywords: m-government; ethics; ethical frameworks; municipal service delivery; e-government; mobile technology
  • Full Text:
  • Date Issued: 2021

A critical appraisal of the recruitment and selection process of the Public Protector in South Africa

  • Authors: Bazana, Sandiso , Reddy, Tayra
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/453707 , vital:75279 , xlink:href=" https://journals.co.za/doi/full/10.4102/sajhrm.v19i0.1207"
  • Description: Orientation: The process of recruitment and selection the Public Protector (PP) needs to ensure that the most ‘fit and proper’ candidate is appointed. The process needs critical scrutiny for such a fit and proper candidate to be selected. Research motivation: South Africa’s superior courts, including the Constitutional court have recently (in 2019) labelled the current Public Protector; dishonest and Incompetent in carrying out the duties of the PP office. Research purpose: This article critically appraises the recent process that culminated in the appointment of Ms Busisiwe Mkhwebane as the fourth Public Protector in the democratic South Africa.
  • Full Text:
  • Date Issued: 2021

A Critical Review of Environmental Governance, Land Restitution, and Tourism in Protected Areas

  • Authors: Ramukumba, Takalani
  • Date: 2021
  • Subjects: Tourism Land use Environmental protection Wildlife conservation Article
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/7029 , vital:52756 , xlink:href=":https://doi.org/10.46222/ajhtl.19770720.200"
  • Description: Natural areas, when protected, conserve the natural environment and function as social spaces in which tourism brings increased income, employment, and financial support for conservation. The inclusion of local community members in the planning and management of protected areas has been on the rise since the early 1900s. Tourism has been advocated as a strategy that can help in achieving economic development, especially in rural areas. However, governance issues and potential negative impacts of tourism development have been under inspection. Conservation efforts in Southern Africa especially in the late 1800s and early 1900s had negative impacts on the local communities since this led to many communities being displaced or having limited access to these protected areas. This has seen the need for ways and efforts to get local community members' despondency and attitudes towards protected areas change such that in the 20th century, there were efforts to use conservation models that included community members in the decision-making and benefit-sharing process to garner their support for protected areas. This paper reviews literature on environmental governance, land restitution in protected areas, tourism in protected areas, co-management, and the importance of community participation. These concepts are reviewed using Manyeleti Game Reserve as a case study. Keywords: Tourism, land restitution, environmental governance, wildlife resources, and stakeholder participation
  • Full Text:
  • Date Issued: 2021

A decade of biological control of Parthenium hysterophorus L.(Asteraceae) in South Africa reviewed: introduction of insect agents and their status

  • Authors: Strathie, L W , Cowie, Blair W , McConnachie, Andrew J , Chidawanyika, Frank , Musedeli, Jufter N , Sambo, SMC , Magoso, EX , Gareeb, M
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/416795 , vital:71386 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a11"
  • Description: The annual herb, Parthenium hysterophorus L. (Asteraceae: Heliantheae) is a severe terrestrial invader globally. Infestations reduce crop yield, limit available grazing, hinder conservation efforts, and affect human and animal health in Africa, Asia and Australia, and on associated islands. Due to the impact and threat of further invasion of P. hysterophorus, a biological control (biocontrol) programme was initiated in 2003 in South Africa. This review discusses the research and implementation activities undertaken on the insect agents from 2011 to 2020. During this period, the stem-boring weevil Listronotus setosipennis Hustache (Coleoptera: Curculionidae), leaf-feeding beetle Zygogramma bicolorata Pallister (Coleoptera: Chrysomelidae) and seed-feeding weevil Smicronyx lutulentus Dietz (Coleoptera: Curculionidae), were found to be host specific and approved for release. Releases of mass-reared insect agents have been concentrated particularly in north-eastern South Africa, where P. hysterophorus infestations are most prolific. Post-release monitoring studies indicated localised establishment and impact of L. setosipennis and S. lutulentus. Listronotus setosipennis persisted through severe drought conditions, and although it disperses slowly, larval feeding is structurally damaging. Establishment of S. lutulentus is improving, reducing seed production where it is established. Zygogramma bicolorata resulted in defoliation at a few sites, but establishment has been poor and the beetle has been absent since 2019. Although a combination of fungal and insect agents were demonstrated to reduce P. hysterophorus, additional natural enemies could improve control. Consequently, the stem-galling moth Epiblema strenuana Walker (Lepidoptera: Tortricidae) and root-crown boring moth Carmenta sp. nr. ithacae (Beutenmüller) (Lepidoptera: Sesiidae) remain under evaluation. The management of P. hysterophorus in South Africa has been guided by the development of a national strategy, which incorporates multiple management methods, including biocontrol. International collaborations have intensified as a growing number of countries begin to utilize biocontrol to manage P. hysterophorus. Despite the progress towards biocontrol of P. hysterophorus during this period, increased utilisation of approved agents and the introduction of additional agents are necessary to achieve greater control.
  • Full Text:
  • Date Issued: 2021

A framework to test South Africa’s readiness for the fourth industrial revolution

  • Authors: Olaitan, Olutoyin O. , Issah, Moshood , Wayi, Ntombovuyo
  • Date: 2021
  • Subjects: Industry 4.0 Article
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/11260/7153 , vital:53072 , xlink:href=" https://doi.org/10.4102/sajim.v23i1.1284"
  • Description: Background: The fourth industrial revolution (4IR) is being touted as having the capacity to lift South Africa out of the challenges of poverty, unemployment and inequitable distribution of wealth. However, the state of the country’s readiness for the enabling technologies of the 4IR is in question. Objective: This article sought to investigate South Africa’s state of readiness for the technologies that enable the 4IR. The article proposed a framework which can be used to measure the country’s level of preparedness and implement the necessary processes to move the country into the 4IR era. Method: A detailed analysis of literature was carried out on the current and futuristic technologies employed by developed countries as they moved towards the 4IR. The fit – viability and the task – technology theories were employed to propose a framework to government for measuring its state of readiness for the 4IR in South Africa. Results: Based on findings from the literature study, the article proposed the 4IR readiness framework for government to measure and subsequently plans its response to the advent of 4IR technologies in the country. Conclusion: The framework revealed that South Africa has low technological capability, plummeting economic complexity and a fall in digital technological readiness. There is also a dearth of skilled workforce and technological infrastructure. It was recommended that government should focus on building and strengthening the resilience of both public and private institutions, investment in relevant 4IR education, infrastructural improvement, and promulgation and enforcement of legal framework to ensure security and privacy of data. Keywords: 4IR; task – technology; fit – viability; digital technology readiness; economic complexity
  • Full Text:
  • Date Issued: 2021

A heavy-atom-free π-extended N-confused porphyrin as a photosensitizer for photodynamic therapy

  • Authors: Babu, Balaji , Mack, John , Nyokong, Tebello
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/185909 , vital:44447 , xlink:href="https://doi.org/10.1039/d1nj00112d"
  • Description: The synthesis and characterization of a novel 1,3-diethyl-2-thiobarbituric-acid-substituted N-confused porphyrin (NCP-TB) is reported, along with a study of its photodynamic activity against MCF-7 cells using 530 (110 mW cm−2) and 660 nm (280 mW cm−2) Thorlabs light-emitting diodes for 30 min. The singlet oxygen quantum yield for NCP-TB is 0.38 compared to 0.23 for the parent unsubstituted N-confused porphyrin (NCP) due to the presence of a sulfur atom. NCP-TB exhibits enhanced PDT activity compared to NCP at both wavelengths. A significantly lower IC50 value of 5.2 μM was obtained at 530 nm (14.7 μM at 660 nm) despite a smaller light dose, due to a large red shift of the intense B band into the green region of the spectrum. 2′,7′-Dichlorofluorescein diacetate (DCFDA) assays demonstrate that there is intracellular generation of reactive oxygen species upon exposure to light.
  • Full Text:
  • Date Issued: 2021

A laboratory simulation investigating the impact of sunglass tint on the catching performance of cricket fielders

  • Authors: Nellemann, Stacy Amanda
  • Date: 2022-04-06
  • Subjects: Sunglasses , Cricket Physiological aspects , Cricket players , Glare , Vision , Contrast sensitivity (Vision) , Fielders (Cricket)‎
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/291281 , vital:56839
  • Description: Background: Sunglasses are popularly worn by outdoor athletes such as cricketers. They are primarily worn to preserve ocular health due to the length of time exposed to the sun’s glare on the field. More recently, sunglasses are now worn for their purported performance-enhancing benefits supposedly allowing athletes to “see clearly, react faster and perform with confidence”. Fielders typically wear sunglasses, but it is rare to see the bowler or the batter wearing sunglasses although they are exposed to the same conditions. If sunglasses provide visual clarity for better reaction time, it is assumed this would also be beneficial for both batsmen and bowlers alike. It is interesting that although fielding plays a key role in the winning of a match, it has received very little research in comparison to the areas of batting and bowling. Research concerning sunglasses in the past has been concerned with its effect on ocular parameters such as colour vision and contrast sensitivity, with minimal research on their effect on performance, specifically on how different colour tints may affect performance such as catching in fielding. Objective: The purpose of this study was to compare the catching performance of fielders when wearing three different colour tints of sunglasses. Methods: Thirty male cricketers currently playing for Rhodes University or country districts sides in Makhanda, South Africa, who were non-habitual sunglass wearers were recruited for this study. An optician administered a pre-screening test to ensure participants did not have any visual defects that would affect the results, determining who was eligible to continue with the research project. Twenty-five participants qualified with a further four withdrawing during the experimentation phase due to personal reasons. Eligible participants were required to complete four testing sessions on separate days thereafter in which they wore a different colour tint at each session (clear, blue, G30 and red). These tints were randomised among participants. Participants were required to catch 18 balls projected from a bowling machine in each session. The number of balls caught as well as the quality of catch was recorded. At the end of the fourth session, participants were presented with a questionnaire investigating their subjective experience of the protocol and preference for any particular colour of lens. Results: Statistically significant results were found between the different colour lenses for the ocular parameters of contrast sensitivity and stereopsis tested by the optician. The red lens was found to be the best for contrast sensitivity with the blue lens performing the worst on this test. With regard to stereopsis, the G30 lens was the worst, with the red lens performing the best. The performance measures resulted in no significant difference between the different colour lenses both concerning the total number of catches taken as well as the quality of catch taken. The same result was found irrespective of the colour of lens used in each session. Data gathered from the questionnaire regarding visual comfort and target visibility resulted in the red lens being rated statistically worse than the other three conditions. In terms of personal preference, the G30 lens was rated statistically as the best coloured lens. Conclusion: It can be concluded that objectively there is no difference in performance between the three coloured lenses. Although from an ocular perspective, the red lens was expected to perform the best in terms of catching performance, there was no difference. Subjectively there was a strong preference among the players for the G30 lens with players strongly disliking the red lens. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
  • Full Text:
  • Date Issued: 2022-04-06

A new species of Buyisa Distant, 1907 (Hemiptera Cicadidae Cicadettinae Cicadettini) from South Africa

  • Authors: Sanborn, Allen F , Villet, Martin H
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/441318 , vital:73877 , https://doi.org/10.4289/0013-8797.123.1.199
  • Description: A new species of the cicada genus Buyisa Distant, 1907 is described from South Africa for an undetermined species referenced in the literature. Buyisa eccaensis new species is described and illustrated and notes on its biology are provided. A key to the officially described species of Buyisa is also included.
  • Full Text:
  • Date Issued: 2021

A new species of red toad, Schismaderma Smith, 1849 (Anura: Bufonidae), from central Angola

  • Authors: Baptista, Ninda L , Pinto, Pedro V , Keates, Chad , Edwards, Shelley , Rödel, Mark-Oliver , Conradie, Werner C
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/461462 , vital:76204 , xlink:href="https://www.biotaxa.org/Zootaxa/article/view/zootaxa.5081.3.1"
  • Description: A new species of red toad, from the previously monotypic genus Schismaderma, is described. The new species was found in Malanje Province, and seems endemic to central Angola, occurring approximately 500 km west of the closest known records of Schismaderma carens. Unusual adult colouration and geographical distance to remaining S. carens populations suggested specific differentiation. In an integrative approach, we compared the red toads from central Angola with S. carens from across the entire range, including molecular data, morphology of adults and tadpoles, and male advertisement calls. Phylogenetic analysis based on mitochondrial (12S, 16S, COI) and nuclear (CXCR4, RAG1) markers, retrieved the Angolan clade as monophyletic, and revealed intra-specific substructuring among the remaining Schismaderma. Genetic distances supported specific differentiation of the central Angolan material compared with other S. carens. Adults from the new Angolan species have bolder ventral patterning and smaller body size than S. carens. No obvious differences were detected between the tadpoles and the advertisement calls of the two Schismaderma species. This discovery adds to the knowledge of the herpetofauna of the Angolan Miombo woodlands, a poorly understood ecoregion, and likely more biodiverse than previously assumed. The result of past river basin dynamics in central Angola likely led to the evolution of this new species of Schismaderma.
  • Full Text:
  • Date Issued: 2021

A population genetics study of Pale-winged Starlings, Onychognathus nabouroup, using novel microsatellite markers

  • Authors: Munshi, Naadhira , Symes, Craig , Maayer, Pieter de , Craig, Adrian J F K , Henry, Laurence , Hausberger, Martine , Mollett, Jean
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/448718 , vital:74754 , https://www.ajol.info/index.php/scopus/article/view/211291
  • Description: Recent research into starling species has revealed the existence of vocal social markers and a link between song temporal structuring and social organisation. The aim of the present study was to develop a genetic tool for understanding the population structuring and behaviour (social/parental transmission) and mating in Pale-winged Starlings (Onychognathus nabouroup), a songbird which is found in arid areas of southern Africa. Using next-generation sequencing, microsatellite markers comprising six dinucleotides, eighteen trinucleotides and twenty-four tetra-nucleotides specific to the Pale-winged Starling were isolated and developed. A total of 77 birds were sampled from the Augrabies Falls Nature Reserve in South Africa (n= 53) and the Ai Ais-Richtersveld Transfrontier Park resort in Namibia (n= 24), respectively. Fifteen polymorphic microsatellite markers were genotyped. The statistical programme STRUCTURE revealed four different genetic clusters within the two populations.
  • Full Text:
  • Date Issued: 2021

A review of the biocontrol programmes against aquatic weeds in South Africa

  • Authors: Coetzee, Julie A , Bownes, Angela , Martin, Grant D , Miller, Benjamin E , Smith, Rosali , Weyl, Philip S R , Hill, Martin P
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/406965 , vital:70326 , xlink:href="https://hdl.handle.net/10520/ejc-ento_v29_n3_a18"
  • Description: Biological control (biocontrol) against invasive macrophytes is one of the longest standing programmes in South Africa, initiated in the 1970s against water hyacinth, Pontederia crassipes Mart. (Pontederiaceae). Since then, 15 agent species (13 insects, one mite and one pathogen) have been released against six weeds, most of which are floating macrophytes, with excellent levels of success. The release of the water hyacinth planthopper Megamelus scutellaris Berg (Hemiptera: Delphacidae) in particular, has improved biocontrol prospects for water hyacinth since 2018. In the last decade, however, a new suite of submerged and rooted emergent invasive macrophytes has been targeted. The first release against a submerged macrophyte in South Africa, and the first release against Brazilian waterweed, Egeria densa Planch. (Hydrocharitaceae), anywhere in the world, was achieved with the release of a leafmining fly, Hydrellia egeriae Rodrigues-Júnior, Mathis and Hauser (Diptera: Ephydridae). Yellow flag, Iris pseudacorus L. (Iridaceae) and Mexican waterlily, Nymphaea mexicana Zucc. (Nymphaeaceae), have also been targeted for biocontrol for the first time worldwide, and are in the early stages of agent development. Post-release evaluations, long term monitoring and controlled experiments have highlighted the need for a more holistic approach to managing aquatic invasive plants in South Africa, whose presence is largely driven by eutrophication, resulting in regime shifts between floating and submerged invaded states.
  • Full Text:
  • Date Issued: 2021

A Review of the Siyakhula Living Lab’s Network Solution for Internet in Poor Communities

  • Authors: Muchatibaya, Hilbert , Terzoli, Alfredo , Dlodlo, Nomusa
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/474279 , vital:77698 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9577006"
  • Description: Changes within ICT over the past decade required a review of the network solution deployed in the Siyakhula Living Lab (SLL), a joint venture between the Universities of Fort Hare and Rhodes, focused on finding blueprints for sustainable e-infrastructure in poor communities. The review found that the topology used in the SLL’s network is still viable but WiMAX is now outdated. Also, the in-network cache, Squid, is no longer effective, given the switch to HTTPS, the strong presence of advertising, and the data weight of current web pages. The solution to the first issue is outdoor Wi-Fi, a proven solution easily deployable in grass-roots fashion. The second issue can be cured leveraging Squid’s ‘bumping’ and splicing features; deploying a browser extension to make picture download optional; and using Pi-hole, a DNS sinkhole. Hopefully, the revised solution could become a component of South African Government’s broadband plan, “SA Connect”.
  • Full Text:
  • Date Issued: 2021

A Robust Portable Environment for First-Year Computer Science Students

  • Authors: Brown, Dane L , Connan, James
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/465113 , vital:76574 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-030-92858-2_6"
  • Description: Computer science education in both South African universities and worldwide often aim at making students confident at problem solving by introducing various programming exercises. Standardising a computer environment where students can apply their computational thinking knowledge on a more even playing field – without worrying about software issues – can be beneficial for problem solving in classroom of diverse students. Research shows that having consistent access to this exposes students to core concepts of Computer Science. However, with the diverse student base in South Africa, not everyone has access to a personal computer or expensive software. This paper describes a new approach at first-year level that uses the power of a modified Linux distro on a flash drive to enable access to the same, fully-fledged, free and open-source environment, including the convenience of portability. This is used as a means to even the playing field in a diverse country like South Africa and address the lack of consistent access to a problem solving environment. Feedback from students and staff at the Institution are effectively heeded and attempted to be measured.
  • Full Text:
  • Date Issued: 2021

A wideband spectropolarimetry study of the spatially resolved radio galaxies: Cygnus A & Hydra A

  • Authors: Sebokolodi, Makhuduga Lerato Lydia
  • Date: 2022-04-04
  • Subjects: Radio astronomy , Radio galaxies , Faraday effect , Astrophysical spectropolarimetry , Intracluster medium , Cosmic magnetic fields
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/454415 , vital:75342 , DOI 10.21504/10962/454415
  • Description: This study presented results from our deep, wideband, high-spectral and high-spatial-resolution polarisation observations of the two most powerful radio galaxies, namely Cygnus A and Hydra A, with the Jansky Very Large Array (JVLA). The high surface brightness and strong polarisation of these radio sources enabled detailed polarimetric imaging, providing images at 0.75′′ resolution across 2−18 GHz and 2000 independent lines-of-sight across Cygnus A, and images at 1.5′′ (2 − 12 GHz) and 600 lines-of-sight across Hydra A. Our data revealed significant depolarisation and depolarisation structure, as well as deviations from a _2-law. We also found complicated structures in the Faraday spectra ranging from single-peaked to blended/resolved double- and multiple-peaked. The Faraday spectra of Hydra A were more multiple-peaked than Cygnus A. The fractional polarisation increased monotonically with increasing resolution, as expected. However, there were numerous lines-of-sight with complicated behaviour. We also found that the structure and complexity in the depolarisation increased at lower resolutions, suggesting substantial spatial structures across the lobes/tails. We fitted the 0.3′′ (6−18 GHz) and 0.50′′ (6−12 GHz) images of Cygnus A and Hydra A, respectively, with a simple model incorporating random, unresolved fluctuations in the cluster magnetic field to determine the high-resolution, high-frequency properties of the sources and the cluster. We found rotation measures (RM) between −5000 rad m−2 and +6400 rad m−2 across Cygnus A, and −2000 rad m−2 and +11900 rad m−2 across Hydra A, consistent with previous studies. From these derived properties, we generated predicted polarisation images of the sources at lower frequencies (< 6 GHz), convolved to 0.75′′ for Cygnus A and 1.5′′ for Hydra A. The predictions were remarkably consistent with the observed emission in both sources, providing strong support for the depolarisation being a result of unresolved fluctuations in the magnetic fields. We fitted various analytical models to the wideband data. We found that the data for both sources were inconsistent with a wholly mixed gas of thermal and synchrotron gas, particularly for regions withRM > 1000 rad m−2. Instead, the data required a dominant Faraday rotating screen in the foreground of the radio sources. The wideband modelling also showed preference towards models with at least two or more unresolved Faraday rotating patches. Single depolarising models fail to describe the data. This implies the presence of more than one depolarising screen in the vicinity of these sources. The observations were consistent with the lower-frequency depolarisation due to unresolved fluctuations on scales ≳ 300−700 pc in the magnetic field or the electron density superposed on a partially ordered field component. Both the large-scale magnetic fields and unresolved magnetic field fluctuations are external to the radio emission. The magnetic fields around Cygnus A are located in the ambient cluster gas, the shocked gas in the boundary of the lobes or both, while the magnetic fields around Hydra A are most likely located in the ambient cluster gas. , Thesis (PhD) -- Faculty of Science, Physics, 2022
  • Full Text:
  • Date Issued: 2022-04-04

Academic or ‘zoombie’? Characterizing sleep quality, work and lifestyle behaviours among a cohort of South African academic staff during the Covid-19 pandemic

  • Authors: Le Grange, Sarah-Ann
  • Date: 2022-04-06
  • Subjects: Sleep-wake cycle South Africa Eastern Cape , Sleep Physiological aspects , Lifestyles Health aspects South Africa Eastern Cape , COVID-19 Pandemic, 2020- Influence , Work environment Psychological aspects , Work environment Physiological aspects , College teachers Workload South Africa Eastern Cape , Pittsburgh Sleep Quality Index (PSQI)‎
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/291099 , vital:56818
  • Description: Working in academe is characterized by high work demands, long and late working hours and balancing multiple roles. This often leaves academic staff (interchangeably referred to as ‘academics’ and ‘staff’) with limited time to prioritize adequate rest and sleep. While sufficient sleep is important for general well-being and work performance, it may be important for academics given the cognitive and interactive nature of their work. However, limited research has characterized sleep behaviours and sleep quality in academic staff globally and specifically in South Africa (SA). Further, research shows that academics from different academic ranks and genders differ in their work experiences but less is known about whether these factors affect their sleep and lifestyle factors. Over and above the demands of academic work, the current study was conducted during COVID-19, which saw unprecedented change in workloads for academic staff due to online teaching and learning. Additionally, the pandemic has been associated with poorer sleep quality and lifestyle behaviours in the general population, but very few studies have explored this in the context of academics. Thus, this study aimed to characterize the sleep quality, work and lifestyle factors among academics from a university in the Eastern Cape province of SA and determine the effects of gender and academic rank on these measures. Additionally, the study aimed to determine the impact of COVID-19 on sleep and work-related factors of this group. This study adopted a cross-sectional design and made use of an online questionnaire that was distributed to all academics employed at the institution via email. The data collection occurred over an 8-week testing period between August and September of 2020. The questionnaire explored sociodemographic, work and lifestyle characteristics, while the characteristics of sleep and sleep quality were explored with the Pittsburgh Sleep Quality Index (PSQI). Additionally, an open-ended section was included to determine the impact of COVID-19-related changes on sleep and work. The questionnaire responses were analyzed with descriptive and inferential statistics and the open-ended questions were analyzed with thematic analyses. A total of 84 respondents completed the questionnaire. On average, sleep quality was poor (global score of 7.09 ± 3.8), the reported sleep duration was short (6.41 ± 1.06 hrs) and the group was classified as overweight according to median BMI (26.67 [23.8-2 29.45] kg/m2). Over a third (35.71%) of academic staff reported not meeting physical activity guidelines and reported using screens one hour prior to bed every night during the week (76.19%) and the weekend (67.88%). Staff also worked long total weekly work hours (54.25 ± 11). Female academics had a poorer sleep quality (p = 0.035), spent a longer time in bed (p = 0.04), experienced more bad dreams (p = <0.01), had their last serving of alcohol earlier (p = 0.04) and worked less weekday (p = 0.04) and less total weekly (p = 0.02) hours compared to male academics. Professorship-level academics were significantly older than junior- and senior-level academics (p = <0.01) while senior-level academics had a poorer PSQI compared to professorship-level academics (p = 0.03). The thematic analysis showed that home environment, neighbourhood noise, work and mental health were the main emerging factors that disturbed sleep. The thematic analysis showed that, in relation to the impact of COVID19, sleep schedules changed and sleep duration and sleep quality improved or got worse. Respondents reported their work hours increasing, work schedules becoming less routine while working from home, dealing with the challenges of working online and experiencing worry, stress and anxiety due to the pandemic. The study highlights that, in the context of lockdown and having to work and teach online from home, academics reported poor quality sleep and short sleep duration. Further, on average, the sample reported working extensive hours and unhealthy lifestyle behaviours. The sleep health, nature of work and overall lifestyles of academic staff deserves more research attention, given the importance of their work and the impact that inadequate sleep could have on academics’ health and work performance. Sleep quality was worse for females and mid-career academics, suggesting that their sleep quality may be at greater risk than other sub-groups. However, the reasons for these differences need to be explored in future studies. The findings contribute to the narrative that academe involves numerous demands and supports previous research that has suggested that academics’ sleep is insufficient. Furthermore, COVID-19 had an impact on staff’s sleep, with staff reporting changes in their sleep quality and duration. The pandemic impacted work of academics by presenting novel demands related to online teaching, intensifying demands overall and disrupting work routines. However, future research is needed to understand academics’ sleep behaviours, work and lifestyles, especially in South Africa. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2022
  • Full Text:
  • Date Issued: 2022-04-06

Accelerated implementations of the RIME for DDE calibration and source modelling

  • Authors: Van Staden, Joshua
  • Date: 2021
  • Subjects: Radio astronomy , Radio inferometers , Radio inferometers -- Calibration , Radio astronomy -- Data processing , Radio inferometers -- Data processing , Radio inferometers -- Calibration -- Data processing
  • Language: English
  • Type: text , Thesis , Masters , MSc
  • Identifier: http://hdl.handle.net/10962/172422 , vital:42199
  • Description: Second- and third-generation calibration methods filter out subtle effects in interferometer data, and therefore yield significantly higher dynamic ranges. The basis of these calibration techniques relies on building a model of the sky and corrupting it with models of the effects acting on the sources. The sensitivities of modern instruments call for more elaborate models to capture the level of detail that is required to achieve accurate calibration. This thesis implements two types of models to be used in for second- and third-generation calibration. The first model implemented is shapelets, which can be used to model radio source morphologies directly in uv space. The second model implemented is Zernike polynomials, which can be used to represent the primary beam of the antenna. We implement these models in the CODEX-AFRICANUS package and provide a set of unit tests for each model. Additionally, we compare our implementations against other methods of representing these objects and instrumental effects, namely NIFTY-GRIDDER against shapelets and a FITS-interpolation method against the Zernike polynomials. We find that to achieve sufficient accuracy, our implementation of the shapelet model has a higher runtime to that of the NIFTY-GRIDDER. However, the NIFTY-GRIDDER cannot simulate a component-based sky model while the shapelet model can. Additionally, the shapelet model is fully parametric, which allows for integration into a parameterised solver. We find that, while having a smaller memory footprint, our Zernike model has a greater computational complexity than that of the FITS-interpolated method. However, we find that the Zernike implementation has floating-point accuracy in its modelling, while the FITS-interpolated model loses some accuracy through the discretisation of the beam.
  • Full Text:
  • Date Issued: 2021

Adaptation and validation of a computerized neurocognitive battery in the Xhosa of South Africa

  • Authors: Cobb, Scott J , Moore, Tyler M , Stein, Dan J , Pretorius, Adele , Zingela, Zukiswa , Nagdee, Mohammed , Ngqengelele, Linda , Campbell, Megan M , Sibeko, Goodman , King, Mary C , McClellan, Jon M , Port, Allison M , Jackson, Chad , Ruparel, Kosha , Susser, Ezra , Gur, Ruben C
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/302439 , vital:58196 , xlink:href="https://doi.org/10.1037/neu0000742"
  • Description: Objective: Large-scale studies have revolutionized biomedical research, and neurocognitive tests can help elucidate the biological basis of neuropsychiatric diseases. However, studies have predominantly been conducted in Western settings. We describe the development and validation of a computerized battery (PennCNB) with the Xhosa population of South Africa. Method: Individuals with schizophrenia (n = 525) and a normative comparison group (n = 744) were balanced on age, sex, education, and region. Participants provided blood samples, were assessed psychiatrically, and were administered a PennCNB translation to isiXhosa, including measures of executive functions, episodic memory, complex cognition, social cognition, and sensorimotor speed. Feasibility was examined with test completion rates and input from administrators, and psychometric structural validity and associations with clinical and demographic characteristics were examined. Results: Tests were well tolerated by participants, as >87% had one (or fewer) test missing. Results suggested a similar factor structure to prior PennCNB studies in Western contexts, and expected age and sex effects were apparent. Furthermore, a similar profile of schizophrenia was observed, with neurocognitive deficits most pronounced for executive functions, especially attention, as well as memory, social cognition, and motor speed relative to complex cognition and sensorimotor speed. Conclusions: Results support the feasibility of implementing a culturally adapted computerized neurocognitive battery in sub-Saharan African settings and provide evidence supporting the concurrent validity of the translated instrument. Thus, the PennCNB is implementable on a large scale in non-Western contexts, shows expected factor structure, and can detect cognitive deficits associated with neuropsychiatric disorders. Obtaining valid measures of cognition by nonspecialized proctors is especially suitable in resource-limited settings, where traditional testing is prohibitive. Future work should establish normative standards, test–retest reliability, and sensitivity to treatment.
  • Full Text:
  • Date Issued: 2021

Adaptive machine learning based network intrusion detection

  • Authors: Chindove, Hatitye E , Brown, Dane L
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/464052 , vital:76471 , xlink:href="https://doi.org/10.1145/3487923.3487938"
  • Description: Network intrusion detection system (NIDS) adoption is essential for mitigating computer network attacks in various scenarios. However, the increasing complexity of computer networks and attacks make it challenging to classify network traffic. Machine learning (ML) techniques in a NIDS can be affected by different scenarios, and thus the recency, size and applicability of datasets are vital factors to consider when selecting and tuning a machine learning classifier. The proposed approach evaluates relatively new datasets constructed such that they depict real-world scenarios. It includes analyses of dataset balancing and sampling, feature engineering and systematic ML-based NIDS model tuning focused on the adaptive improvement of intrusion detection. A comparison between machine learning classifiers forms part of the evaluation process. Results on the proposed approach model effectiveness for NIDS are discussed. Recurrent neural networks and random forests models consistently achieved high f1-score results with macro f1-scores of 0.73 and 0.87 for the CICIDS 2017 dataset; and 0.73 and 0.72 against the CICIDS 2018 dataset, respectively.
  • Full Text:
  • Date Issued: 2021

Adaptive network intrusion detection using optimised machine learning models

  • Authors: Chindove, Hatitye E , Brown, Dane L
  • Date: 2021
  • Subjects: To be catalogued
  • Language: English
  • Type: text , article
  • Identifier: http://hdl.handle.net/10962/465634 , vital:76627 , xlink:href="https://www.researchgate.net/publication/358046953_Adaptive_Network_Intrusion_Detection_using_Optimised_Machine_Learning_Models"
  • Description: Network intrusion detection system (NIDS) adoption is essential for mitigating computer network attacks in various scenarios. However, the increasing complexity of computer networks and attacks make it challenging to classify network traffic. Machine learning (ML) techniques in a NIDS can be affected by different scenarios, and thus the recency, size and applicability of datasets are vital factors to consider when selecting and tuning a machine learning classifier. The proposed approach evaluates relatively new datasets constructed such that they depict real-world scenarios. It includes empirical analyses of practical, systematic ML-based NIDS with significant network traffic for improved intrusion detection. A comparison between machine learning classifiers, including deep learning, form part of the evaluation process. Results on how the proposed approach increased model effectiveness for NIDS in a more practical setting are discussed. Recurrent neural networks and random forests models consistently achieved the best results.
  • Full Text:
  • Date Issued: 2021
  • Disclaimer
  • Privacy
  • Copyright
  • Contact