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Prognosis of the end-of-life of lithium iron phosphate batteries with application in large-scale electric buses
Get PDFPoonah, B. 2025. Prognosis of the End-of-Life of Lithium Iron Phosphate Batteries with application in Large-Scale Electric Buses. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/dfb789a0-cdce-49d7-8c4e-ec7d4c897bd6Thesis (MEng)--Stellenbosch University, 2025.ENGLISH ABSTRACT: The electrification of public transport vehicles is rapidly advancing due to its considerable environmental benefits and alignment with global carbon neutrality goals. However, this shift presents significant challenges, such as the need for trip scheduling and substantial infrastructure investments. While these practicalities are critical, the focus of this thesis is on a pivotal yet frequently overlooked factor: the aging of Lithium-ion batteries, which serve as electric vehicles' (EVs) primary energy source. Lithium-ion battery capacity declines inevitably, further accelerated by environmental conditions and end-user behavior. This study, therefore, investigates the specific aging mechanisms of Lithium Iron Phosphate (LFP) batteries to pinpoint primary causes of aging under standard operating conditions, with the aim of mitigating long-term impacts. To enable state of health (SoH) and early lifetime estimations, various models are reviewed to assess their applicability and constraints, especially under data-limited scenarios. The semi-empirical and equivalent circuit models (ECM) are identified as the most suitable low-complexity approaches. Additionally, the recent developments in data-driven models are examined for their capacity to improve SoH estimation and predict remaining useful life (RUL) by incorporating external factors, including driver behavior and environmental conditions. Considering the importance of data variety and availability, publicly accessible battery datasets are reviewed for their potential in real-world applications, noting their limitations to laboratory-generated conditions and usefulness primarily in early-life predictions. Historical field battery data, sourced from the battery management systems (BMS) of forklifts and reach trucks, is analyzed to address these limitations. Key challenges arise due to the minimal utility of raw field battery data for aging prognostics, prompting the development of specific algorithms in Python in order to reconstruct missing information. Furthermore, a modified coulomb counting model is proposed to estimate SoH labels over the historical field battery dataset. Insights from the historical data then facilitate the calibration of a semi-empirical model that aligns with observed SoH trends over time. The resulting SoH labels are compared to the semi-empirical model to verify the calibration, and the model is subsequently extrapolated to the end-of-life (EoL) condition. The estimated RUL of the battery is projected to extend approximately 11 years and 6 months, assuming minimal deviations in future operating conditions.AFRIKAANSE OPSOMMING: Die elektrifisering van voertuie wat vir openbare vervoer gebruik word, neem vinnig toe as gevolg van die aansienlike omgewingsvoordele en die doelwit om wˆereldwyd koolstofneutraliteit te bereik. Hierdie skuif bring egter beduidende uitdagings mee, soos die behoefte aan ritbeplanning en groot infrastruktuurbeleggings. Terwyl hierdie praktiese uitdagings van groot belang is, fokus hierdie tesis op ’n sleutelaspek wat dikwels oor die hoof gesien word: die veroudering van Litium-ioon-batterye, wat die primˆere kragbron van elektriese voertuie (EVs) is. Litium-ioon-batterykapasiteit neem onvermydelik af, wat verder vererger word deur omgewingstoestande en eindgebruikersgedrag. Hierdie studie ondersoek dus die spesifieke verouderingsmeganismes van Litium-ysterfosfaat (LFP)-batterye om die primˆere oorsake van veroudering onder normale bedryfstoestande te identifiseer, met die doel om die langtermyn-impakte te versag. Om die bepaling van gesondheidstoestand (SoH) en vroe¨e lewensduur-skatting moontlik te maak, word verskeie modelle hersien om hul toepaslikheid en beperkings, veral in data-beperkte scenario’s, te assesseer. Die semi-empiriese en gelykstaande kringmodelle (ECM) word as die mees geskikte lae-kompleksiteit benaderings ge¨ıdentifiseer. Daarbenewens word die onlangse ontwikkelinge in data-gedrewe modelle ondersoek vir hul vermo¨e om die bepaling van SoH te verbeter en oorblywende bruikbare lewensduur (RUL) te voorspel deur eksterne faktore soos bestuurdersgedrag en omgewingstoestande in ag te neem. Aangesien die verskeidenheid en beskikbaarheid van data belangrik is, word publiek toeganklike battery-datastelle hersien vir hul potensiaal in werklike toepassings, met die opmerking dat hierdie datastelle beperk is tot data wat in laboratoriumtoestande gegenereer is en hoofsaaklik bruikbaar is vir vroe¨e-lewe-voorspellings. Historiese veldbattery-data, verkry vanaf die batterybestuurstelsels (BMS) van vurkhysers en bereik vragmotors, word ontleed om hierdie beperkings aan te spreek. Belangrike uitdagings ontstaan weens die beperkte nut van rou veldbattery-data vir verouderingsprognose, wat die ontwikkeling van spesifieke algoritmes in Python vereis om ontbrekende inligting te rekonstrueer. Verder word ’n aangepaste Coulomb-telmodel voorgestel om SoH-etikette oor die historiese veldbattery-dataset te skat. Inligting uit die historiese data fasiliteer dan die kalibrasie van ’n semi-empiriese model wat ooreenstem met waargenome SoH-neigings oor tyd. Die resulterende SoH-etikette word vergelyk met die semi-empiriese model om die kalibrasie te verifieer, en die model word daarna uitgebrei tot die eind-van-lewe (EoL) kondisie. Die geskatte RUL van die battery word op sowat 11 jaar en 6 maande beraam, met die aanname dat toekomstige bedryfstoestande min sal afwyk.Master
Determining the direct benefits and costs of prescribed burning : a case study of the Langeberg Mountain veld area, Western Cape, South Africa
Get PDFThesis (MScAgric)--Stellenbosch University, 2025.Muyima, G. 2025. Determining the direct benefits and costs of prescribed burning: a case study of the Langeberg Mountain veld area, Western Cape, South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/e7937c6b-71cf-4de2-b50b-9eebec02e8b0ENGLISH SUMMARY: Wildfires are common in the South African environment. Fires are a natural phenomenon and essential for maintaining several natural ecosystems, such as grasslands and fynbos. They often cause significant damage to property, land, livestock, and plantations, threaten human lives and are expensive to contain. Veldfires are influenced by three main factors: weather, landscape, and available fuels. Available fuels may be considered the most important, as they are the only factor that can be mitigated. Without the reduction of available fuels, there is a build-up of biomass. Prescribed burning provides a means of controlling fuel loads. Otherwise, biomass build-up from suppressed fire can lead to a catastrophic fire as dead plant material burns more quickly and intensifies the fire. There are direct benefits and costs incurred in prescribed burning for fuel reduction. This study determined the direct benefits and costs of prescribed burning in the Langeberg Mountain veld area, Western Cape, South Africa. Primary data were sourced through questionnaires. Then, a financial cost-benefit analysis (CBA) was performed to enable the rational and systematic capture and comparison of costs and benefits. The results revealed that the potential benefits that could be derived from prescribed burning far exceeded the costs of burning. The study implied that society would benefit from prescribed burning (this is seen in the potential private farm profits and the cost saving of extinguishing wildfires), however, there are implementation costs involved though the implementation costs are not higher than the possible costs of extinguishing wildfires. The Department of Forestry previously practised a policy of regular prescribed burning to rejuvenate the fire-dependent vegetation and reduce fuel loads. Now the National Veld and Forest Fire Act No. 101 of 1998 uses a “caller pays” principle which states that the landowner or fire implementing agent is liable should prescribed burns on their property spread and damage surrounding properties and they should cover the cost of firefighting resources, putting all responsibilities on the farmers. The Act proved to be a limiting factor to prescribed burning as 69,23% of farmers did not burn the veld due to fear of being financially liable should prescribed burning spread from their property. However, the financial cost-benefit analysis result suggests that prescribed burning should be recommended to farmers and other landowners in the Langeberg Mountain veld area, as benefits exceeded costs. Nonetheless, this does not remove the risk associated with prescribed burning on the farmers' side. Controlled burns can become wildfires causing damage to property and human safety for which the farmer may be held legally liable. Since farmers are risk-averse, more incentives are required to participate in prescribed burning. Still, as it is today, the burden is placed on farmers. The Department of Agriculture, Forestry and Fisheries (DAFF) should meet the farmers midway to give them more incentives by minimising the risk of farmers' partaking in prescribed burning. Such incentives should include the relaxation or softening of the NVFFA and participation of the department in prescribed burning through subsidizing the preparation, maintenance and burning of fire breaks.AFRIKAANSE OPSOMMING: Veldbrande is algemeen in die Suid-Afrikaanse omgewing. Brande is 'n natuurlike verskynsel en noodsaaklik vir die instandhouding van verskeie natuurlike ekosisteme, soos grasvelde en fynbos. Hulle veroorsaak dikwels aansienlike skade aan eiendom, grond, vee en plantasies, bedreig menselewens en is duur om in bedwang te hou. Veldbrande word deur drie hooffaktore beinvloed: weer, landskap en beskikbare brandstof. Beskikbare brandstof kan as die belangrikste beskou word, aangesien dit die enigste faktor is wat versag kan word. Sonder die vermindering van beskikbare brandstof is daar 'n opbou van biomassa. Voorgeskrewe verbranding bied 'n manier om brandstofladings te beheer. Andersins kan biomassa-opbou van onderdrukte brand tot 'n katastrofiese brand lei aangesien dooie plantmateriaal vinniger verbrand en die brand vererger. Daar is direkte voordele en koste verbonde aan voorgeskrewe verbranding vir brandstofvermindering. Hierdie studie het die direkte voordele en koste van voorgeskrewe verbranding in die Langebergbergveldgebied, Wes-Kaap, Suid-Afrika bepaal. Primere data is deur middel van vraelyste verkry. Daarna is 'n finansiele koste-voordeel-analise (KBA) uitgevoer om die rasionele en sistematiese vaslegging en vergelyking van koste en voordele moontlik te maak. Die resultate het aan die lig gebring dat die potensiele voordele wat uit voorgeskrewe verbranding verkry kan word, die koste van verbranding ver oorskry het. Die studie het geimpliseer dat die samelewing baat sou vind by voorgeskrewe verbranding (dit word gesien in die potensiele private plaaswinste en die kostebesparing van die blus van veldbrande), maar daar is implementeringskoste betrokke alhoewel die implementeringskoste nie hoer is as die moontlike koste van die blus van veldbrande nie. Die Departement van Bosbou het voorheen 'n beleid van gereelde voorgeskrewe verbranding toegepas om die brandafhanklike plantegroei te verjong en brandstoflading te verminder. Nou gebruik die Nasionale Veld- en Bosbrandwet No. 101 van 1998 'n "beller betaal"-beginsel wat bepaal dat die grondeienaar of brandimplementeringsagent aanspreeklik is indien voorgeskrewe brandwonde op hul eiendom versprei en omliggende eiendomme beskadig en hulle moet die koste van brandbestrydingshulpbronne dek, wat alle verantwoordelikhede op die boere plaas. Die Wet het geblyk 'n beperkende faktor vir voorgeskrewe brand te wees aangesien 69,23% van boere nie die veld gebrand het nie weens vrees om finansieel aanspreeklik te wees indien voorgeskrewe brand van hul eiendom sou versprei. Die finansiele koste-voordeel-ontledingsresultaat dui egter daarop dat voorgeskrewe verbranding aan boere en ander grondeienaars in die Langebergberg-veldgebied aanbeveel moet word, aangesien voordele die koste oorskry. Dit verwyder nietemin nie die risiko verbonde aan voorgeskrewe brand aan die boere se kant nie. Beheerde brandwonde kan veldbrande word wat skade aan eiendom en menslike veiligheid veroorsaak waarvoor die boer wetlik aanspreeklik gehou kan word. Aangesien boere risiko-sku is, word meer aansporings vereis om deel te neem aan voorgeskrewe verbranding. Steeds, soos dit vandag is, word die las op boere geplaas. Die Departement van Landbou, Bosbou en Visserye (DLBV) behoort die boere halfpad te ontmoet om hulle meer aansporings te gee deur die risiko van boere se deelname aan voorgeskrewe verbranding te verminder. Sulke aansporings moet die verslapping of versagting van die NVFFA en deelname van die departement aan voorgeskrewe verbranding insluit deur die voorbereiding, instandhouding en brand van brandbane te subsidieer.Master
Digital resilience and continued use of mobile payment services in a developing economy
Get PDFThesis (PhD)--Stellenbosch University, 2025.Alhassan, M. D. 2025. Digital resilience and continued use of mobile payment services in a developing economy. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch Univeristy [online]. Available: https://scholar.sun.ac.za/items/f116e241-1ef0-4d66-a5d4-d358a7283274ENGLISH SUMMARY: In developing economies, particularly in sub-Saharan Africa, the use of mobile phones for financial transactions has been increasing. These transactions can be done with smartphones or feature phones using SMS payments, also known as mobile money services. While mobile money services offer convenience, there is a growing issue of mobile payment fraud, resulting in subscribers losing funds stored in their mobile payment wallets. Although there is some empirical knowledge about how users can protect their funds and information from fraudsters, there is limited empirical evidence on why users continue to use mobile payment services after experiencing fraud, particularly in African developing economies. This study aimed to investigate the role of digital resilience in users' continued use of mobile payment services in Ghana, as a representative example of a developing economy. The main objective was to identify the antecedents of digital resilience by concentrating on the factors that promote users' continued use of mobile payment services after fraud and use the antecedents to develop a new measurement scale for users' digital resilience in the face of mobile payment fraud experiences in developing economies. The study utilised the socio-ecological resilience framework and exploratory sequential mixed method to identify the factors that contribute to digital resilience and to develop a scale for measuring individuals' digital resilience in the face of digital adversities such as online fraud. In the first phase of the research, a systematic review was conducted to identify the factors that promote individual digital resilience to online victimisation. Thematic analysis of the systematic review articles using ATLAS.ti revealed six factors that promote individual digital resilience to digital adversities: personal competence, social competence, acceptance of self and life, positive emotions, structured style, and social resources. The second phase involved semi-structured interviews with 31 individuals who had experienced mobile payment fraud. Thematic analysis of the interview data identified eight factors that influenced users' continued use of mobile payment services after experiencing fraud: personal competence, social competence, acceptance of self and life, positive emotions, satisfaction with service provider support, social resources, perceived utility, and trust in government policies. The third stage of the research included a synthesis of systematic review and semi-structured interview findings to arrive at a comprehensive set of digital resilience dimensions for developing a new digital resilience scale. The synthesis of systematic review and semi-structured interview findings revealed nine digital resilience dimensions, including personal competence, social competence, acceptance of self and life, positive emotions, satisfaction with service provider support, social resources, perceived utility, and trust in government policies. The measurement items for the dimensions of personal competence, social competence, acceptance of self and life, positive emotions, structured style, and social resources were adapted from previously validated scales from the literature. New items were developed for the dimensions of satisfaction with service provider support, social resources, perceived utility, and trust in government policies, given that no scales exist in the literature for these dimensions. Initially, 61 measurement items were developed to measure the nine digital resilience dimensions. Acceptance of self and life, personal competence, structured style, positive emotions, service provider support, perceived utility, and government policies were each measured by seven items. Social resources and social competence were each measured by six items. The proposed digital resilience scale was sent to 10 experts in the fields of information systems, psychology, human resources, and mobile money services to assess its face and content validity. The experts' feedback was incorporated into the research scale, and it was administered to a sample of 280 users of mobile payment services in Ghana to empirically assess the scale's reliability and validity. Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA) were utilised to assess the reliability and validity of the scale, with the help of SPSS and SmartPLS4 respectively. Results from the EFA showed that the measurement items best explained six dimensions. Specifically, the items measuring personal competence and structured style loaded on one dimension. Similarly, the measurement items for trust in government policies and satisfaction in service provider support loaded on one dimension. Also, social resources and social competence had their measurement items loading on one dimension. Confirmatory factor analysis confirmed the six-dimensional structure as revealed by the EFA. The six-dimension scale, including 40 measurement items, showed a better model fit and was found to be reliable and valid for future research purposes. With regard to the conceptualisation of digital resilience, this research sufficiently contributes to the existing understanding of digital resilience by providing a different perspective that specifically relates to mobile payment fraud. As far as could be established, no research has explored how individuals build their digital resilience to online fraud as a technological stressor. Thus, this study provides empirical evidence to show that the previous conceptualisation of digital resilience as mainly relating to online adversities such as online bullying, sexting, and exposure to inappropriate or user-generated content may be limited in scope and not provide an overall understanding of the concept of digital resilience. This current study indicates that in developing economies such as Ghana, digital resilience may not be limited to online adversities including online bullying and sexting, but also how individuals recover from online fraud experiences to decrease the negative impact of financial losses on their trust and continued reliance on digital technologies. Also, this study developed a measurement scale to effectively measure users' digital resilience to technological adversities including online fraud. As far as could be established, no measurement scale existed in the literature to measure users' digital resilience to online fraud experiences. Therefore, by developing and empirically validating a measurement scale to measure users' digital resilience, this study provides a unique operationalisation of digital resilience with measurement items that can reliably capture the dimensions of digital resilience. Furthermore, the measurement scale may be adapted by future studies to examine individual digital resilience to various technological stressors in both developed and developing economies.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.Doctora
'n God-wat-straf in 'n Plattelandse Gemeente konteks? die Klaaglied van Dogter Sion (Klaagliedere 2) Gelees deur 'n trauma lens
Get PDFThesis (MTh)--Stellenbosch University, 2025.Coetzer, J. H. 2025. 'n God-Wat-Straf in 'n Plattelandse Gemeente konteks?
Die Klaaglied van Dogter Sion (Klaagliedere 2) Gelees deur 'n
Trauma Lens. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/fc3ce9a1-20a8-4950-8ccf-9edb48be218fENGLISH SUMMARY: This thesis examines the concept of divine punishment within the rural context of the Dutch Reformed Church, with a specific focus on how natural phenomena, as well as other forms of suffering, are interpreted as a manifestation of God's punishment. This study has its origins in pastoral experiences with congregants who believe that God is punishing them by sending natural disasters, such as hailstorms. By examining Lamentations 2, the research seeks to understand how trauma, experienced by individuals as well as communities, is portrayed in biblical literature. The aim is to re-frame the traditional understanding of a Godwho-punishes image by means of trauma hermeneutics, to investigate questions about theodicy, that is, God's involvement during suffering. This study argues that although biblical texts often portray God as a God-who-punishes, there are ways in which the lens of trauma theory can form part of the healing process. The research relies on the framework of trauma specialists, such as Judith Herman, Kathleen O'Connor, Christopher Frechette and Elizabeth Boase. Herman's three phases,
which include safety, mourning and reintegration, are applied to Lamentations 2. Lamentations 2 is a text that gives voice to the immense emotional and spiritual suffering of the Judean people during the Babylonian exile. By bringing trauma theory into conversation with biblical metaphors and literary techniques, Lamentations 2 offers a way in which parishioners can articulate their own experiences of trauma and develop new language. This study makes the argument that the poetic and metaphorical nature of Lamentations are powerful elements that can be used when processing trauma. This study suggests that the reinterpretation of violent biblical narratives through the lens of trauma can help parishioners move from a God-who-punishes image to a view that sees God as present and compassionate in times of need. Finally, the study attempts to offer practical guidelines that equip ministers to conduct responsible discussions with parishioners within contexts where the God-who-punish image prevails. The research of this study contributes to the ongoing conversation around the understanding of theodicy during pastoral conversations where trauma is dealt with.AFRIKAANSE OPSOMMING: Hierdie proefskrif ondersoek die konsep van Goddelike straf binne die plattelandse konteks van die NG Kerk, met 'n spesifieke fokus op hoe natuurverskynsels, sowel as ander vorme van lyding, as 'n manifestering van God se straf geinterpreteer word. Hierdie studie het sy oorsprong uit pastorale ondervindings met gemeentelede wat van die oortuiging is dat God hulle straf deur natuurverskynsels, soos haelstorms, te stuur. Deur Klaagliedere 2 te ondersoek poog die navorsing om te verstaan hoe trauma, wat deur individue, sowel as gemeenskappe beleef word, in Bybelse literatuur uitgebeeld word. Die doel is om die tradisionele verstaan van ‘n God-wat-straf beeld te her-raam deur middel van trauma hermeneutiek, om sodoende vrae oor teodisee, oftewel, God se betrokkenheid tydens lyding, te ondersoek. Hierdie studie argumenteer dat alhoewel Bybelse tekste God gereeld voorstel as ’n God-wat-straf, daar wyses is waarby die lens van trauma teorie deel kan vorm van die heling proses. Die navorsing steun op die raamwerk van trauma spesialiste, soos Judith Herman, Kathleen O’Connor, Christopher Frechette en Elizabeth Boase. Herman se drie fases, wat veiligheid, rou en her-integrasie insluit, word op Klaagliedere 2 van toepassing gemaak. Klaagliedere 2 is ‘n teks wat ‘n stem gee vir die geweldige emosionele en spirituele lyding van die Judeers tydens die Babiloniese ballingskap. Deur trauma teorie met Bybelse metafore en literere tegnieke in gesprek met mekaar te bring, bied Klaagliedere 2 ‘n wyse waardeur gemeentelede hul eie ervarings van trauma kan verwoord en nuwe taal ontwikkel. Hierdie studie argumenteer dat die poetiese en metaforiese aard van Klaagliedere kragtige elemente is wat tydens die verwerking van trauma gebruik kan word. Hierdie studie stel voor dat die herinterpretasie van gewelddadige Bybelse narratiewe, deur die lens van trauma, gemeentelede kan help om vanaf ‘n God-wat-straf beeld te beweeg na ‘n siening van God as teenwoordig en medelydend in tye van nood. Laastens poog die studie om praktiese riglyne te bied wat predikante toerus om binne kontekste waar die God-wat-straf beeld seevier, verantwoordelike gesprekke met gemeentelede te voer. Die navorsing van hierdie studie dra by tot die aanhoudende gesprek rondom die verstaan van teodisee tydens pastorale gesprekke waar trauma hanteer word.Master
Investigating the role of compassion in the well-being of SAICA Article Clerks
Get PDFThesis (MCom)--Stellenbosch University, 2025.Janse van Rensburg, J. 2025. Investigating the Role of Compassion in the Well-Being of SAICA Article Clerks. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/fcdbfdb5-925e-4831-8cd4-ea2eec5fd472ENGLISH SUMMARY: The role of accountants in the labour market has become increasingly significant due to their critical skills and knowledge, which are necessary to make crucial, strategic business decisions. Employees in the South African accountancy profession often face toilsome demands such as time pressures, role ambiguity, and work overload. These job demands adversely impact the occupational well-being of chartered accountants, leaving them more susceptible to burnout and lower levels of work engagement. High levels of burnout and low engagement result in increased turnover intentions, which in turn contribute to the current shortage of chartered accountants in South Africa. To address this shortage, this quantitative research study aimed to identify factors that may influence the variance in burnout and employee engagement among SAICA article clerks. The study utilised the Job Demands-Resources (JD-R) model as a guiding framework to investigate the levels of burnout and engagement among this group of employees, together with their levels of job demands (work overload), job resources (compassionate leadership), and personal resources (self-compassion). A structural model that exhibits the relationships between these variables, was proposed and empirically tested through structural equation modelling. To determine the validity of the arguments put forward in the literature review, several research hypotheses were postulated. These hypotheses were tested by employing an ex-post facto correlational design. Non-probability, convenience sampling was employed to select the sample, which consisted of 168 SAICA article clerks who, at the time of this study, worked at an accounting firm in South Africa. The variables of interest were evaluated through an online questionnaire, where participation was anonymous and completely voluntary. The following measures were included: the Burnout Assessment Tool (BAT-12); the Utrecht Work Engagement Scale (UWES-9); the Quantitative Workload Inventory (QWI); a composite scale comprising items from The Experienced Compassion at Work Scale and the Relational Compassion Scale (RCS); and the Self-Compassion Scale-Short Form (SCS-SF). Of the eight hypotheses tested, the four main effects proved statistically significant, whereas the remaining four moderating effects were found to be non-significant. Results confirmed a significant negative relationship between burnout and employee engagement, a positive effect of compassionate leadership on employee engagement, a positive influence of self-compassion on employee engagement, and a significant positive relationship between work overload and burnout. Two novel relationships were revealed, namely that compassionate leadership (as a job resource), as well as self-compassion (as a personal resource), both exert a significant direct negative influence on job burnout. Findings also suggested that burnout was equally prevalent during all three years of clerkship and that accounting firms should aim to allocate job resources to each group, instead of singling out a particular year group. This study could potentially provide organisational leaders and human resource practitioners with valuable insights as to why certain SAICA article clerks are more susceptible to burnout, and why some have higher levels of work engagement than others. Furthermore, based on the study findings, the researcher proposed possible interventions that accounting firms could implement to reduce burnout and increase engagement among SAICA clerks, to obtain and maintain a competitive advantage through their human capital.AFRIKAANSE OPSOMMING: Die rol van rekeningkundiges op die arbeidsmark het al hoe belangriker geword weens hul kritiese denkvaardighede en kennis, wat noodsaaklik is om belangrike, strategiese besluite in besighede te neem. Werknemers wat in die Suid-Afrikaanse rekeningkunde-professie werk, word dikwels gekonfronteer met harde vereistes soos tydsdruk, rolverwarring en werk oorbelasting. Hierdie werkeise het 'n negatiewe impak op die beroepswelstand van geoktrooieerde rekenmeesters, wat hulle meer vatbaar maak vir uitbranding en laer vlakke van werksbetrokkenheid. Hoë vlakke van uitbranding en lae vlakke van betrokkenheid lei tot verhoogde omloopintensies, wat op hul beurt bydra tot die huidige tekort aan geoktrooieerde rekenmeesters in Suid-Afrika. Om hierdie tekort aan te spreek, het hierdie kwantitatiewe navorsingstudie ten doel gehad om faktore te identifiseer wat die variasie in uitbranding en werknemerbetrokkenheid onder SAICA-artikelklerke kan beïnvloed. Die studie het die Job Demands-Resources (JD-R) model as 'n riglyn gebruik om die vlakke van uitbranding en betrokkenheid onder hierdie groep werknemers te ondersoek, saam met hul vlakke van werkeise (werk oorbelasting), werkhulpbronne (medelydende leierskap), en persoonlike hulpbronne (selfdeernis). 'n Strukturele model wat die verhoudings tussen hierdie veranderlikes uitbeeld, is voorgestel en empiries getoets deur middel van strukturele vergelykingsmodellering. Om die geldigheid van die argumente wat in die literatuuroorsig voorgestel is, te bepaal, is verskeie navorsingshipotese gestel. Hierdie hipotese is getoets deur 'n eks-post facto korrelasionele ontwerp te gebruik. Nie-waarskynlikheids, gerieflikheidsmonitering is gebruik om die steekproef te kies, wat bestaan het uit 168 SAICA-artikelklerke wat, ten tyde van hierdie studie, by 'n rekeningkundige firma in Suid-Afrika gewerk het. Die veranderlikes van belang is geevalueer deur middel van 'n aanlyn-vraelys, waar deelname anoniem en heeltemal vrywillig was. Die volgende maatstawwe is ingesluit: die Burnout Assessment Tool (BAT-12); die Utrecht Work Engagement Scale (UWES-9); die Quantitative Workload Inventory (QWI); die Experienced Compassion at Work Scale; die Relational Compassion Scale (RCS); en die Self Compassion Scale-Short Form (SCS-SF). Van die agt hipoteses wat getoets is, het die vier hoof effekte statisties beduidend bewys, terwyl die oorblywende vier modererende effekte nie beduidend was nie. Resultate het 'n beduidende negatiewe verhouding tussen uitbranding en werknemerbetrokkenheid bevestig, 'n positiewe effek van medelydende leierskap op werknemerbetrokkenheid, 'n positiewe invloed van selfdeernis op werknemerbetrokkenheid, en 'n beduidende positiewe verhouding tussen werk oorbelasting en uitbranding. Twee nuwe verhoudings is onthul, naamlik dat medelydende leierskap (as 'n werkhulpbron), sowel as selfdeernis (as 'n persoonlike hulpbron), albei 'n beduidende direkte negatiewe invloed op werksuitbranding het. Bevindinge het ook voorgestel dat uitbranding ewe algemeen voorgekom het gedurende al drie jare van klerkskap en dat rekeningkundige firmas moet poog om werksbronne aan elke groep toe te ken, eerder as om 'n spesifieke jaargroep uit te sonder. Hierdie studie kan moontlik organisasie-leiers en menslike hulpbronpraktisyns waardevolle insigte verskaf oor hoekom sekere SAICA-artikelklerke meer vatbaar is vir uitbranding en hoer vlakke van werksbetrokkenheid as ander. Verder, gebaseer op die studie bevindings, het die navorser moontlike intervensies voorgestel wat rekeningkundige firmas kan implementeer om uitbranding te verminder en betrokkenheid te verhoog onder SAICA-klerke, ten einde 'n mededingende voordeel te behaal en te handhaaf deur middel van hul menslike kapitaal.Master
Reward functioning in posttraumatic stress disorder, metabolic syndrome, and psychological resilience
Get PDFThe original publication is available at: https://www.sciencedirect.com/Background: Reward system dysfunction may play a role in the comorbidity of metabolic syndrome (MetS) in posttraumatic stress disorder (PTSD). Psychological resilience, through its effects on the reward system, may modulate outcomes in PTSD. Utilising a monetary incentive delay task during functional magnetic resonance imaging in a case-control study (PTSD, n = 88, trauma-exposed controls [TEC], n = 85), we aimed to investigate reward system function in relation to PTSD, MetS, and psychological resilience.
Methods: Using repeated measures analysis of variance, we assessed change in activation in the ventral striatum (VS) during reward anticipation and in the orbitofrontal cortex (OFC) during reward outcome, in relation to PTSD, MetS, and psychological resilience, controlling for possible confounders including depression severity, childhood trauma and trauma load.
Results: Activation in the VS and OFC didn't differ in relation to PTSD and MetS. When we controlled for depression severity, PTSD cases had significantly lower activation in the VS and a greater increase in activation in the OFC compared to TEC. Psychological resilience was significantly associated with decreased change in activation in the VS and increased change in activation in the OFC. We also observed a greater increase in activation during reward outcome in the OFC in those with greater childhood trauma exposure and those with exposure to fewer lifetime traumatic events.
Conclusions: The effects of depression and psychological resilience on reward system function in PTSD can be utilised towards developing interventions targeted at altering positive valence systems in PTSD.https://www.sciencedirect.com/science/article/pii/S0925492724001410#Publisher’s versio
The overall volumetric oxygen transfer coefficient in high viscosity, alginate-rich media
Get PDFThe original publication is available at https://www.sciencedirect.com/scienceUnderstanding the impact of alginate, or similar high-viscosity polymers, on the oxygen transfer in aerobic bioprocess is critical in bioprocess development. Further, in the case of alginate lyase production, it is common for the media to also include significant concentrations of NaCl, which alters the ionic strength and impacts KLa. The results show that in alginate containing media, as the concentration of alginate increases, the fluid viscosity increases, leading to the reduction in KLa. However, comparison of the water-air and water-alginate-air systems revealed that at increased agitation rates (i.e. > 200 rpm) the KLa is enhanced in the water-alginate-air system as compared to the water-air system. This enhancement of KLa was seen up to 10.5 g/L of alginate. We propose this is due to two competing effects. Under lower alginate concentration, the influence of NaCl on bubble size and formation properties enhanced KLa in comparison to the water-air system. However, an additional increase in alginate concentration resulted in the reduction of KLa as the effect of increased viscosity, which reduces the liquid phase mass transfer, became the dominant effect. These results suggest that for fermentation utilising viscous media, operating under lower alginate concentrations may prevent oxygenation issues. Furthermore, the observations made emphasise the need to consider additives such as NaCl in fermentation media when estimating KLa.https://www.sciencedirect.com/science/article/pii/S1369703X24004078Publisher’s versio
Investigation of Tuberculosis in Domestic Goats (Capra aegagrus hircus) in KwaZulu-Natal
Get PDFThesis (PhD)--Stellenbosch University, 2025.Cooke, D. M. 2025. SInvestigation of Tuberculosis in Domestic Goats (Capra aegagrus hircus) in KwaZulu-Natal. Unpublished doctoral thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/38285137-7e2c-4f8f-ad0e-bdf485895863In South Africa (SA), animal tuberculosis (TB) control programs predominantly focus on domestic cattle and to a lesser extent, some wildlife. Despite increasing global reports of TB in goats (Capra hircus), testing and surveillance in domestic rural goats in SA is not common practise. Left undetected, Mycobacterium tuberculosis complex (MTBC) infected goats may hinder TB eradication efforts in cattle, cause mortality or morbidity in goats, and increase zoonotic risk to humans. This study aimed to determine if there was any evidence of M. bovis infection in goats sharing pastures and communal drinking points with known M. bovis infected cattle, and, occurring in the same area as MTBC infected wildlife and humans. Using a cohort of historically TB-negative commercial dairy goats as an M. bovis unexposed control group, immunological and molecular methods for MTBC detection were utilized. The performance of the Department of Agriculture, Land reform and Rural Development's (DALRRD) prescribed single intradermal comparative cervical tuberculin test (SICCT) was evaluated and indicated a low M. bovis prevalence (3%) among the M. bovis exposed goat population. QuantiFERON-TB Gold (QFT) anti-bovine cytokine release assays (interferon gamma release assay, IGRA, and interferon gamma-inducible protein 10 release assay, IPRA) were also evaluated but showed poor responses and were therefore unable to reliably detect immune sensitization in M. bovis exposed goats. In the absence of post-mortem tissue samples for gold standard culture confirmation of M. bovis infection, nasal swabs were collected from each goat for mycobacterial culture and culture-independent MTBC DNA detection. The Cepheid GeneXpert® MTB/RIF Ultra assay (ULTRA) qPCR assay successfully identified MTBC DNA in goat respiratory samples, demonstrating its potential for rapid screening. A Bayesian latent class analysis was performed using IGRA, IPRA, SICCT, and ULTRA results to estimate potential infection prevalence, test sensitivities, and test specificities. The outcome of this analysis estimated the infection prevalence among the M. bovis exposed goats at 1.1%. Viable M. bovis were detected by genus-specific PCRs and Sanger sequencing in 3 nasal swab cultures from the M. bovis exposed goat population, with culture-independent techniques and deep sequencing using region of difference (RD) PCR also confirming the presence of M. bovis DNA in the 3 culture-positive and an additional 8 swabs from M. bovis-exposed goats. Immunological evidence of infection using the SICCT was detected in 82% of goats that had M. bovis DNA in their nasal swabs. The findings of this study confirm the presence of M. bovis infection among communal goats in the Umkhanyakude district of Northern Zululand, KwaZulu-Natal, SA. The high burden of HIV in these areas increases susceptibility to zoonotic infections like M. bovis, particularly among livestock owners who have daily contact with these goats. Goats may well be an under recognized threat to animal TB control efforts in SA, highlighting the need for further investigations and a multi-species, One Health approach for effective animal TB surveillance and control in SA.Doctora
Synthesis and study of novel thiolato-gold(I) complexes as anticancer agents
Get PDFThesis (MSc)--Stellenbosch University, 2025.Scott, S. A. 2025. Synthesis and study of novel thiolato-gold(I) complexes as anticancer agents. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/553d5ca9-4b35-4471-b866-4c06f73fbbaeCancer remains a global health issue and is the second leading cause of death worldwide. Based on the World Health Organisation’s global cancer observatory, 20 million cases and 9.7 million deaths were reported in 2022. Currently there is no perfect treatment for cancer with most chemotherapeutic drugs causing a number of debilitating side effects. The success of the platinum-based drug, cisplatin, resulted in extensive investigation into other metallodrugs. A rise in the incidence of cisplatin resistance also prompted the need for new and effective drugs with targeted mechanisms of action. Drug repurposing is an emerging trend in anticancer drug development as it is faster and more cost effect. The gold(I) drug auranofin, once used to treat rheumatoid arthritis, has been evaluated for repurposing for a number of applications including cancer. The treatment of cancer cells with auranofin and other gold(I) drugs has been shown to target the thioredoxin reductase system as well as other cellular thiols and induce cell death. This project involves the synthesis and characterisation of gold(I) complexes containing both a thiol and a phosphine ligand. The complexes were all obtained in moderate to good yields. Full characterisation was completed and included 1H, 31P and 13C NMR spectroscopy, FT-IR spectroscopy and electrospray ionisation mass spectrometry. The solubility and stability of the complexes were studied under physiological conditions to evaluated how they may react once placed in an aqueous environment. The complexes were evaluated against two cancer cell lines namely, A549 lung cancer and MCF-7 breast cancer and were found to have very good activity against both cell lines but improved activity on the breast cell line. The complexes showed no selectivity for cancer cells over healthy cells as similar levels of activity were seen against the normal cell line HEK-293. They did, however, show less activity when compared to the control drug cisplatin.Master
Investigating the association between hair progesterone, anxiety, sleep quality, and other determinants in South African females
Get PDFThe original publication is available at: https://www.sciencedirect.comBackground: Anxiety symptoms and poor sleep quality are common in women. The role of sex hormones, particularly progesterone, in anxiety and sleep quality in women is understudied. Measurement of hair progesterone concentrations (HPC) is a promising method to investigate the effects of progesterone on anxiety symptoms and sleep quality in women.
Objectives: We analysed sociodemographic, hair-related, and clinical factors associated with HPC and investigated the association between HPC and anxiety severity and sleep quality in a sample of 159 South African women (mean age: 46.5 years; range: 18–79 years).
Methods: Data were obtained from control participants from the SHARED ROOTS study. HPC were determined using an established liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Unadjusted and adjusted multiple linear regression models were used to investigate whether sleep quality, measured with the Pittsburgh Sleep Quality Index (PSQI), and anxiety, measured with the Spielberger State-Trait Anxiety Inventory (STAI), were associated with HPC. Significant sociodemographic, hair-related, and clinical factors were adjusted for.
Results: HPC was significantly associated with age, duration of sample storage, hormonal treatment, postmenopausal status, and the number of different types of trauma exposures in adjusted models. Neither anxiety severity nor sleep quality was significantly associated with HPC.
Conclusions: Certain demographic, hair related, and clinical factors were associated with HPC and need to be considered in future research using HPC. Although anxiety and sleep were not associated with HPC, greater trauma exposure was associated with higher HPC, suggesting an association between severe stress and hypothalamic-pituitary-gonadal (HPG) axis functioning.https://www.sciencedirect.com/science/article/pii/S0306453024002683Publisher’s versio