Targeting treatment resistance in cervical cancer: A new avenue for senolytic therapies

The original publication is available at: https://www.sciencedirect.comCervical cancer poses a significant global health challenge, particularly impacting women in economically developing nations. This disparity stems from a combination of factors, including inadequate screening infrastructure and resource limitations. However, the foremost contributor is the widespread lack of awareness and limited accessibility to Human Papillomavirus (HPV) vaccination, which is a key preventative measure against cervical cancer development. Despite advancements in cervical cancer prevention, treatment resistance remains a major hurdle in achieving improved patient outcomes. Cellular senescence, specifically the senescence-associated secretory phenotype (SASP) and its bidirectional relationship with the immune system, has been implicated in resistance to conventional cervical cancer chemotherapy treatments. The exact mechanisms by which this state of growth arrest and the associated changes in immune regulation contribute to cervical cancer progression and the associated drug resistance are not entirely understood. This underscores the necessity for innovative strategies to address the prevalence of treatment-resistant cervical cancer, with one promising avenue being the utilisation of senolytics. Senolytics are agents that have promising efficacy in clearing senescent cells from tumour tissues, however neither the utilisation of senolytics for addressing senescence-induced treatment resistance nor the potential integration of immunotherapy as senolytic agents in cervical cancer treatment has been explored to date. This review provides a concise overview of the mechanisms underlying senescence induction and the pivotal role of the immune system in this process. Additionally, it explores various senolytic approaches that hold significant potential for advancing cervical cancer research.https://www.sciencedirect.com/science/articlePublisher’s versio

A Comparative Study of the Coagulation Systems and Inflammatory Profiles of Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Patients with Long COVID

Thesis (PhD)--Stellenbosch University, 2025.Arron, H. E. 2025. A Comparative Study of the Coagulation Systems and Inflammatory Profiles of Patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Patients with Long COVID. Unpublished doctoral thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/1a98fb4e-a91f-497b-892e-716a25ee5358Myalgic Encephalomyelitis/Chronic Fatigue Syndrome is a chronic condition that severely debilitates patients, yet it remains largely unfamiliar to many. Faced with scepticism as a real clinical entity for decades, the recognition of ME/CFS has improved with the emergence of Long COVID. This chronic illness manifests after an acute COVID-19 infection. With two-thirds of ME/CFS cases reported to be post-viral, a clear overlap emerges with Long COVID, as both conditions arise following an infectious illness. The parallels between post-infectious ME/CFS and Long COVID are striking, with similarities in both symptomology and pathophysiology. One overlapping mechanism in both conditions, systemic inflammation, may be perpetuated by pathogen persistence or reactivation. While inflammation alone may not be accountable for the symptoms experienced in both conditions, it can lead to disruption in other physiological mechanisms. Owing to a bi-directional link with inflammation, coagulopathy and vascular changes may be exhibited in ME/CFS and Long COVID. Given the accessibility of blood samples, it is imperative to explore these mechanisms to uncover potential biomarkers for these conditions, both of which currently lack standardised diagnostic biomarkers. A total of 83 participants were included in the study. The control group consisted of 19 healthy controls and 10 inflammatory controls (individuals with known inflammatory conditions), used to assess inflammation in a step-increase manner. The post-infectious group included 54 individuals, subdivided into 20 ME/CFS patients and 34 Long COVID patients. Statistical analyses were performed using GraphPad Prism 10 and R-Studio, with comparisons made using parametric or non-parametric tests, depending on data distribution. Significant results were considered at P<0.05. Multiple regression analyses were conducted to control for the effects of age and sex on the outcomes. The techniques utilised in this dissertation focused on Virchow’s triad, a model explaining that hypercoagulability, stasis, and endothelial damage contribute to the aetiology and risk of thrombosis, particularly deep vein thrombosis. Framing the dissertation around this model offered a valuable framework to investigate potential pathological mechanisms and identify relevant biomarkers for these conditions. Common viscoelastic point-of-care devices, including TEG and ClotPro, were employed to examine the hypercoagulability component of Virchow’s triad. These techniques demonstrated how standard laboratory tests are inefficient in revealing pathological alterations in Long COVID and ME/CFS, and how the insignificance of these results has prompted researchers and healthcare professionals to question the validity of these conditions. Despite this, newly developed fluorescent microscopy techniques revealed an increased presence of plasma structures resistant to fibrinolysis in the post-infectious groups, providing evidence of coagulopathy. This technique effectively distinguished the two conditions, with the Long COVID group showing a 2.75-fold increase in these plasma structures compared to the ME/CFS group. Additionally, the post-infectious groups displayed a marked presence of hyperactivated platelets and megakaryocytes in circulation, with platelet activation and aggregation being 1.35-fold higher in the Long COVID group compared to the ME/CFS group. However, such microscopy techniques are low-throughput and labour-intensive, making them less practical for diagnostic purposes. An innovative high-throughput diagnostic technique known as real-time deformability cytometry was employed to investigate the second component of Virchow’s triad: alterations in blood rheology. When isolating anomalous events and large clots in whole blood using the combined filter technique, the Long COVID group showed a 1.30-fold decrease in deformation compared to the ME/CFS group, indicating greater rigidity of these structures. Additionally, the ME/CFS group had a 1.31-fold decrease in the volume of these clots compared to the Long COVID group. Although significant differences were observed in both conditions and likely impact blood rheology, this technique requires further standardisation due to its novelty. Lastly, endothelial biomarkers previously studied in other inflammatory diseases were investigated to better understand the extent of endothelial damage, the final aspect of Virchow's triad. The flow luminescence immunoassay revealed a 1.29-fold reduction in cadherin-5 levels in the ME/CFS group compared to healthy controls. No significant differences were found in other endothelial biomarkers between the post-infectious groups, suggesting these biomarkers cannot be repurposed for these conditions. Furthermore, the lack of replicability in endothelial analyte concentrations among different studies raises concerns about the reproducibility of this technique. When the findings of this dissertation are considered collectively through biomarker stratification, it becomes clear that distinct subgroups may exist within the studied populations. This highlights the importance of a multiparameter approach for diagnosis, although these novel investigations require further validation and should be replicated with larger sample sizes. Through an examination of these mechanisms, this dissertation illustrated some commonalities between these diseases and demonstrated how Virchow's triad may be implicated to some extent in both conditions. However, key differences were also identified between the conditions, highlighting the unique challenges each presents. As we investigate whether Long COVID signals the early onset of ME/CFS and consider whether insights gained from decades of combating ME/CFS can enlighten our understanding of Long COVID, we progress toward a deeper understanding of post-infectious conditions and the creative solutions required to address them.Doctora

Exploring the commodification of African culture in popular media and its impact on African identities: A comparative analysis of Amapiano and Afrobeats music genres

Thesis (MA)--Stellenbosch University, 2025.Majola, K. L. 2025. Exploring the commodification of African culture in popular media and its impact on African identities: A comparative analysis of Amapiano and Afrobeats music genres. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/1260b354-0119-42ab-970d-e419b8edf50fENGLISH ABSTRACT: This research study investigates how global institutions influence how ‘African-ness’ is represented and perceived when African artists collaborate with international stars. This sheds light on the underlying power dynamics and cultural exchanges. The primary research question is, to what extent does mass media accurately depict African culture, and does it risk appropriation for predominantly White audiences? This study contributes to the field of enquiry by conducting empirical research on the understudied Amapiano genre. It builds on the body of knowledge concerning the development of music in South Africa by adding contemporary research on its recent social and technological influences. It further echoes the existing sentiment that a better representation of the continent needs to be made in mainstream media. The aim is to contribute to the field of enquiry by highlighting the challenges fuelled by the interplay between corporations, institutions and technological tools introduced in the 21st century, which have shifted the music production process and the distribution of music. The main objective is, therefore, to provide a lens through which both genres are experienced by various audiences, including fans, critics, and media institutions. To achieve this, I drew upon two significant music projects that engaged the African diaspora – The Lion King: The Gift album produced by Beyonce Knowles and Tyla’s hit single Water. A qualitative case study was adopted to present geographically contrasting contexts of two of Africa’s most developed economies: South Africa and Nigeria. The research design took the form of a qualitative content analysis where twenty media sources were selected and analysed for their relevance to the subject matter, alongside two significant YouTube videos. The data findings revealed that mass media exploits African culture to some capacity as it relates to other global cultures. Although there are attempts to create space and inclusiveness, it’s a half-hearted attempt to add more faces and voices for ‘diversity’ purposes rather than education.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar nie.Master

Teachers’ experiences of children’s participation rights in Grade One classrooms

Thesis (MEd)--Stellenbosch University, 2025.De Bruyn, N. 2025. Teachers’ Experiences of Children’s Participation Rights in Grade One Classrooms. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/df2d6cf3-f141-41f1-ac68-0ef7b868f279ENGLISH ABSTRACT: This study explored teachers’ experiences of children’s participation rights in their Grade One classrooms. The aim was to investigate how South African teachers understand and support children’s participation rights, as outlined in legislation, and the spaces and strategies they create to enable children to exercise these rights within the classroom context. Additionally, it covered the challenges teachers face when involving children in decision-making processes, as well as the types of support they need to overcome these challenges effectively. Children’s participation rights are a well-researched phenomenon that has gained substantial traction in South African research in recent years. However, a discrepancy still exists between research and teachers’ awareness of these rights and, consequently, their implementation. Hart’s Ladder of Participation (Hart, 1992) and Lundy’s Voice Model (Lundy, 2007) were used as the conceptual framework. I used an interpretive, qualitative, multiple-case study approach to examine and understand the experiences of Grade One teachers regarding child participation. To select the six Grade One teachers as participants, I employed a combination of purposive and snowball sampling from three schools in the Western Province. Data collection methods included questionnaires, photovoice, photo-elicitation interview, a focus group, and notes from my research journal. Four themes emerged from the inductive thematic data analysis focused on the outcomes of teachers’ experiences regarding child participation. The four identified themes were consequently, Teachers’ Awareness of Child Participation Rights, Supporting Child Participation in Classroom Contexts, Perceived Benefits of Supporting Child Participation in Classroom Contexts, and lastly, Factors Influencing the Implementation of Child Participation. The study’s findings indicate teachers’ awareness of children's participation rights and related legislation, as well as how these rights are implemented in classroom settings. Additionally, the findings reveal the potential benefits that teachers perceive when children participate, along with the challenges they encounter in attempting to include children in participatory practices. The study has implications for teachers and teacher training institutions.AFRIKAANSE OPSOMMING: Hierdie studie het onderwysers se ervarings van kinders se deelname-regte in hul Graad Eenklaskamers ondersoek. Die doel was om te ondersoek hoe Suid-Afrikaanse onderwysers kinders se deelname-regte, soos uiteengesit in wetgewing, verstaan en ondersteun, asook die ruimtes en strategieë wat hulle skep om kinders in staat te stel om hierdie regte binne die klaskamerkonteks uit te oefen. Daarbenewens het die studie die uitdagings ondersoek wat onderwysers in die gesig staar wanneer hulle kinders by besluitnemingsprosesse betrek, sowel as die tipe ondersteuning wat hulle benodig om hierdie uitdagings effektief te oorkom. Kinders se deelname-regte is 'n goed nagevorste verskynsel wat die afgelope paar jaar aansienlike aandag in Suid-Afrikaanse navorsing geniet het. Daar bestaan egter steeds 'n gaping tussen navorsing en onderwysers se bewustheid van hierdie regte en, gevolglik, hul implementering daarvan. Hart se Leer van Deelname (Hart, 1992) en Lundy se Stemmodel (Lundy, 2007) is as die konseptuele raamwerk gebruik. Ek het 'n interpretatiewe, kwalitatiewe, veelvuldige gevallestudie-benadering gebruik om die ervarings van Graad Eenonderwysers rakende kinderdeelname te ondersoek en te verstaan. Om die ses Graad Eenonderwysers as deelnemers te kies, het ek 'n kombinasie van doelgerigte en sneeubalsteekproefneming gebruik by drie skole in die Wes-Kaap. Data-insamelingsmetodes het vraelyste, fotostem, foto-elisitasie onderhoud, 'n fokusgroep, en aantekeninge uit my navorsingsjoernaal ingesluit. Vier temas het na vore gekom uit die induktiewe tematiese data-analise wat gefokus het op die uitkomste van onderwysers se ervarings rakende kinderdeelname. Die vier geïdentifiseerde temas was gevolglik: Onderwysers se Bewustheid van Kinderdeelnameregte, Ondersteuning van Kinderdeelname in Klaskontekste, Waargenome Voordele van die Ondersteuning van Kinderdeelname in Klaskontekste, en laastens, Faktore wat die Implementering van Kinderdeelname beïnvloed.Die bevindings van die studie toon onderwysers se bewustheid van kinders se deelname-regte en verwante wetgewing, sowel as hoe hierdie regte in klaskamerinstellings geïmplementeer word. Daarbenewens onthul die bevindings die potensiële voordele wat onderwysers raaksien wanneer kinders deelneem, saam met die uitdagings wat hulle ondervind in pogings om kinders in deelnemende praktyke in te sluit. Die studie het implikasies vir onderwysers en onderwysersopleidingsinstansies.Master

Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations

Thesis (PhD)--Stellenbosch University, 2025.Gerber, M. 2025. Superficial scald on ‘Granny Smith’ – understanding commercial storage protocols and their limitations. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/e71b5efb-3845-4d1c-b5cd-367bca935b5fENGLISH ABSTRACT: Superficial scald is a major postharvest disorder induced by oxidative stress during the first 7 d after harvest, during short-term storage or shipment in a regular atmosphere (RA). The induction period is associated with ethylene-dependent processes and the accumulation of α-farnesene oxidation products like 6‑methyl‑5‑hepten‑one (MHO). Symptoms develop as bronze patches on the fruit peel on transferring the fruit from regular atmosphere (RA) or low-oxygen storage to shipment and shelf‑life conditions. Incidence of more than 1 % on arrival in the overseas market may lead to claims and significant economic losses. This study assessed the efficacy of storage techniques and their combinations used by the South African export industry to control superficial scald. ‘Granny Smith’ apples were subjected to 12 treatments for 4(6), 8, and 16 weeks (short-term) as well as 24, and 33 weeks (long-term) cold storage followed by a simulated 6‑week RA shipment period at −0.5 °C plus a 10-d shelf-life at 20 °C, for three seasons. The fruit were stored under RA (−0.5 °C), with, or without diphenylamine (DPA) (9.6 mL L-1), or 1‑methylcyclopropene (1-MCP) (1 μL L- 1). Low-oxygen storage treatments included controlled atmosphere (CA; 1.5 % O2 and 1.0 % CO2 at 0 °C), dynamic controlled atmosphere ‑ chlorophyll fluorescence (DCA-CF; 0.5 % O2 and 0.7 % CO2 at 0 °C), and cycles of repeated low oxygen stress (RLOS; 0.5 % O2 for 10 d at 0 °C) + ultra-low oxygen storage (ULOS; 0.9 % O2 and 0.8 % CO2 for 21 days) and 0.5 % O2 for 7d at 0 °C. Subsamples of the 1-MCP+CA treated fruit were subjected to a secondary 1‑MCP or DCA‑CF (0.5 % O2 + 0.7 % CO2 for 7 d) or combination (1-MCP+DCA-CF) treatment after long‑term storage, prior to the simulated shipment period. Results indicated that the RA and RLOS+ULOS stored fruit, with or without 1-MCP or DPA, and untreated CA fruit posed a high superficial scald risk during short-term storage plus simulated shipment and shelf-life. Fruit accumulating even low levels of ethylene often posed a higher risk of developing the defect later in storage or shelf-life. DPA treatment did not reduce internal ethylene but reduced scald by preventing the oxidation of α-farnesene to MHO. CA, DCA-CF and RLOS+ULOS in combination with 1-MCP inhibited internal ethylene accumulation and reduced MHO concentrations during short- and long-term storage, however ethylene inhibition did not last during shelf-life after long-term storage. A 1-MCP treatment at harvest and after long-term storage resulted in complete control of superficial scald for these treatments (1-MCP+CA+1-MCP and 1‑MCP+CA+(1‑MCP+DCA‑CF)), even after shipment and shelf-life, and maintained fruit sensory quality. Only complete inhibition of internal ethylene resulted in the prevention of superficial scald incidence for all the storage treatments, except for RLOS+ULOS. Monitoring exogenous ethylene levels during storage and applying a second 1‑MCP treatment after long-term storage before shipping to overseas markets, is advised. This study provided unique insights into the modes of action of different storage techniques to prevent superficial scald in ‘Granny Smith’ apples during short- and long‑term storage.AFRIKAANSE OPSOMMING: Oppervlakkige brandvlek is ’n belangrike na-oesafwyking wat gedurende die eerste 7 dae na oes, tydens korttermynopberging of vervoer in gewone atmosfeer (GA) deur oksidatiewe stres veroorsaak word. Die induksieperiode word geassosieer met etileen-afhanklike prosesse en die akkumulasie van α-farneseen- oksidasieprodukte, byvoorbeeld 6-metiel-5-hepten-een (MHE). Die defeksimptome ontwikkel as brons vlekke op die vrugskil wanneer die vrugte vanaf GA‑ of lae-suurstofopbergingstoestande na verskepings- en raklewetoestande geskuif word. Wanneer meer as 1 % van die vrugte by aankoms in die oorsese mark die defek toon, lei dit to afkeurings en aansienlike ekonomiese verliese. Hierdie studie het die doeltreffendheid van die opbergingsmetodes, en hul kombinasies, soos deur die Suid-Afrikaanse uitvoerbedryf gebruik om oppervlakkige brandvlek te beheer, geëvalueer. ‘Granny Smith’ appels is oor drie seisoene aan 12 koelopbergingsbehandelings vir 4(6), 8 en 16 weke (korttermyn) en 24 en 33 weke (langtermyn) onderwerp. Elke behandeling is gevolg deur ’n gesimuleerde 6‑week GA‑verskepingsperiode teen -0.5 °C en ’n 10-dag rakleweperiode teen 20 °C. Die vrugte is met of sonder diphenylamien (DPA) (9.6 mL L⁻¹) of 1-metielsiklopropeen (1‑MCP) (1 µL L⁻¹) behandeling onder GA (‑0.5 °C) opgeberg. Lae-suurstof opbergingsbehandelings het beheerde atmosfeer (BA; 1.5 % O₂ en 1.0 % CO₂ by 0 °C), dinamiese beheerde atmosfeer-chlorofilfluoresensie (DBA-CF; 0.5 % O₂ en 0.7 % CO₂ by 0 °C), en siklusse van herhaalde lae-suurstofstres (HLSS; 0.5 % O₂ vir 10 d by 0 °C) + ultra‑lae-suurstofopberging (ULSO; 0.9 % O₂ en 0.8 % CO₂ vir 21 d) ingesluit. Monsters van die 1-MCP+BA-behandelde vrugte is na langtermynopberging, voor gesimuleerde verskeping, aan 'n sekondêre 1‑MCP- of DBA-CF-behandeling onderwerp . Resultate het getoon dat GA- en HLSS+ULSO-gebergde vrugte, met of sonder 1-MCP- of DPA‑behandeling, en onbehandelde BA-vrugte ’n hoë risiko vir oppervlakkige brandvlek tydens korttermynopberging plus gesimuleerde verskeping en raklewe ingehou het. Vrugte wat selfs net lae etileenvlakke getoon het, het dikwels 'n hoër oppervlakkige brandvlek risiko later tydens opberging of raklewe gehad. DPA het nie interne etileen verminder nie, maar het skade beperk deur oksidasie van α- farneseen na MHE te voorkom. BA, DBA-CF, en HLSS+ULSO in kombinasie met 1-MCP het interne etileen- en MHE‑konsentrasies tydens kort- en langtermynopberging verminder. ’n 1‑MCP‑behandeling by oes en na langtermynopberging het oppervlakkige brandvlekskade volledig beheer en sensoriese kwaliteit behou in die 1-MCP+BA+1-MCP- en 1-MCP+BA+(1-MCP+DBA-CF)-behandelings. Slegs totale onderdrukking van interne etileen het voorkoming van oppervlakkige brandvleksimptome in al die behandelings, behalwe die HLSS+ULSS-behandeling, verseker. Dit word dus aanbeveel om eksterne etileenvlakke tydens opberging te monitor en ’n tweede 1‑MCP‑behandeling na langtermynopberging, voor verskeping na oorsese markte, toe te dien. Hierdie studie bied unieke insigte betreffende die werking van verskillende opbergingsmetodes om oppervlakkige brandvlek in ‘Granny Smith’ appels tydens kort- en langtermynopberging te voorkom.Doctora

Investigation of Involucral bract browning in Protea spp.

Thesis (MScAgric)--Stellenbosch University, 2025.Smith, A. 2025. Investigation of Involucral Bract Browning in Protea spp. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/e51d8073-0b0f-4d0e-9517-f3f660fa4577ENGLISH ABSTRACT: Involucral bract browning (BB) is a pre-harvest disorder that significantly diminishes the aesthetic appeal and market value of Protea stems, a niche export product for the indigenous South African cut flower industry. Characterized by brown-black involucral bract blemishes, with the severity is increased with post-harvest storage and extended vase life, but not the incidence. Despite the disorder’s severe impact on the economic viability of protea exports, it is largely under-characterized as previous South African export standards only address general blemishes. A six-point classification system for more consistent scoring of incidence and severity for BB was thus proposed. This study explored possible factors influencing BB, including production area, cultivar, and harvest timing. Warmer and drier regions were found to be more prone to BB, particularly for inflorescences maturing in late summer. Cultivars with larger, darker coloured inflorescences visibly exhibited reduced BB severity compared to those with smaller, lighter-coloured inflorescences. Investigating possible physiological and environmental contributors to BB, a split-plot experiment was conducted, using potted Protea ‘Pink Ice’ plants, with temperature as the main effect and irrigation as the secondary factor. Warmed blocks (Ambient +1.6°C) were created using overhead infra-red lights, whilst water deficit irrigation of half optimal (½x), optimal (x), and double optimal (2x) was implemented. Results revealed that elevated temperatures and sub-optimal irrigation (½x) significantly increased BB occurrence while reducing inflorescence size, whereas optimal (x) and supra-optimal (2x) irrigation mitigated BB without negatively affecting plant water status. In a study considering amelioration treatments for BB, waxed paper bags (WPB), non-woven polyethylene (Innoseal) bags, shade netting bags (SNB), along with evaporative cooling (EC), and reflective Raynox Plus™ applications were compared. The WPB and Innoseal treatments showed potential for decreasing BB, whereas the SNB and Raynox Plus™ negatively affected the aesthetic appeal of the inflorescences, whilst the EC treatment was discontinued due to poor irrigation water quality. Covering inflorescences early or throughout their full floral development significantly reduced BB incidence by up to 60% compared to unprotected control stems, whereas limited benefit was derived from covering inflorescence later during development. When comparing the efficacy of overhead fixed 20% white shade netting (SN) to reduce BB compared to that of waxed paper bags (WPB), both treatments effectively reduced BB severity, but SN treatments were less effective in reducing BB than the WPB treatment which delivered larger, market-preferred inflorescences within a more stable temperature environment, without affecting the relative humidity. In a successive season, SN treatments caused minor delays in spring bud break but resulted in an advanced harvest time. While the use of WPB is considered more labour intensive a study comparing it with the cost-effectiveness and long-term sustainability of erecting shade netting is warranted. BB remains a critical concern for Protea production, particularly under predicted increasing harsh and unpredictable climatic conditions. While methods like WPB and SN show promise in mitigating BB, refining these strategies and exploring alternative solutions should be a priority for the South African protea industry.AFRIKAANSE OPSOMMING: Omhullende skutblaarverbruining (BB) is 'n voor-oes-afwyking wat die aantreklikheid en markwaarde van Protea snyblomme, 'n nis-uitvoerproduk vir die inheemse Suid-Afrikaanse snyblombedryf, aansienlik verminder. Hierdie afwyking word gekenmerk deur bruin-swart letsels op die omhullende skutblare waarvan die erns word verhoog met na-oes berging en verlengde vaas lewe, maar nie die voorkoms nie. Ten spyte van die afwyking se ernstige impak op die ekonomiese lewensvatbaarheid van die protea-uitvoerbedyrf, is dit grootliks ondergekenmerk aangesien vorige Suid-Afrikaanse uitvoerstandaarde net enkele letsels aanspreek. 'n Sespunt-klassifikasiestelsel vir meer konsekwente gradering van voorkoms en erns vir BB is dus voorgestel. Hierdie studie het moontlike faktore ondersoek wat BB beïnvloed, insluitend produksie area, kultivar en oes periode. Daar is gevind dat warmer en droër streke meer geneig is tot BB, veral vir bloeiwyses wat in die laat somer volwasse raak. Kultivars wat groter bloeiwyses met ‘n donkerder kleur het sigbaar verminderde BB-erns getoon in vergelyking met dié met kleiner, ligterkleurige bloeiwyses. Om moontlike fisiologiese en omgewingsbydraers tot BB te ondersoek, is 'n split-plot eksperiment uitgevoer, met gebruik van gepotte Protea 'Pink Ice' plante, met temperatuur as die hoof effek en besproeing as die sekondêre faktor. Verwarmde blokke (Omgewing +1.6°C) is geskep deur oorhoofse infrarooi ligte te gebruik, terwyl watertekortbesproeiing van halfoptimaal (½x), optimaal (x) en dubbeloptimaal (2x) geïmplementeer is. Resultate het aan die lig gebring dat verhoogde temperature en sub-optimale besproeiing (½x) die voorkom van BB aansienlik verhoog, wat gelei het tot kleiner terwyl bloeiwyses, terwyl optimale (x) en supra-optimale (2x) besproeiing BB verminder het sonder om plantwaterstatus negatief te beïnvloed. In 'n studie wat beheer metodes vir BB oorweeg, is waspapiersakke (WPB), nie-geweefde poliëtileen (Innoseal) sakke, skadunetsakke (SNB), asook verdampingsverkoeling (EC), en Raynox Plus™-toedienings vergelyk. Die WPB- en Innoseal-behandelings het potensiaal getoon om BB te verlaag, waar die SNB en Raynox Plus™ die aantreklikheid van die bloeiwyses negatief beïnvloed het, terwyl die EC-behandeling gestaak is as gevolg van swak kwaliteit van die water wat gebruik was. Deur bloeiwyses vroeg of regdeur hul volle blomontwikkeling te bedek, het BB-insidensie aansienlik verminder met tot 60% in vergelyking met onbeskermde kontrole bloeiwyses, terwyl beperkte voordeel verkry is uit die bedekking van bloeiwyses later tydens ontwikkeling. Wanneer die doeltreffendheid van oorhoofse vaste 20% wit skadu-net (SN) vergelyk word met dié van waspapiersakke (WPB) om BB te verminder, het beide behandelings die ernstigheid van BB effektief verminder, maar SN-behandelings was minder effektief in die vermindering van BB as die WPB- behandeling wat bo en behalwe groter bloeiwyses, wat dit mark voorkeur gee, gelewer het binne 'n meer stabiele temperatuur omgewing, sonder om die relatiewe humiditeit te beïnvloed. In 'n opeenvolgende seisoen het SN-behandelings geringe vertragings in die lentebot veroorsaak, maar het gelei tot 'n vroeër oestyd. Alhoewel die gebruik van WPB meer arbeidsintensief is, is 'n studie wat dit vergelyk met die koste doeltreffendheid en langtermyn volhoubaarheid van die oprigting van skadunet geregverdig. BB bly 'n kritieke bekommernis vir Protea-produksie, veral onder voorspelde toenemende moeilike en onvoorspelbare klimaatstoestande. Terwyl metodes soos WPB en SN belofte toon om BB te verminder, behoort die verfyning van hierdie strategieë en die ondersoek van alternatiewe oplossings 'n prioriteit vir die Suid-Afrikaanse proteabedryf te wees.Master

Assessing the implementation process for e-Government: a case of the Department of Water and Sanitation

Thesis (MCom)--Stellenbosch University, 2025.Ngxamngxa, T. 2025. Assessing the implementation process for e-Government: A case of the Department of Water and Sanitation. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/d4263814-e41f-4705-8a32-424e6516f7b7ENGLISH ABSTRACT: The thesis assessed the implementation process for electronic government (e-Government) by identifying the Electronic Water Use Licence Application and Authorisation System (E-WULAAS), which is a water use application online portal at the National Department of Water and Sanitation (DWS). The system is a tool developed and implemented for the Water Use Authorisation component to allow water users to submit water use applications electronically and it also allows the department to facilitate and manage the authorisation of the water uses online for the integrated, safety, utilisation, development, conservation, management and control of the country's water resources following the mandate of the National Water Act (NWA), Act 36 of 1998 (Republic of South Africa, 1998). The study aimed to assess the implementation process for e-Government by adopting the 7-C Protocol Instrument for policy implementation into the research, applying the variables of the 7-C Protocol, namely: Content, Context, Commitment, Capacity, Clients and Coalitions, Communication, and Coordination to evaluate the e-Government implementation process at DWS. The literature review presents a distinction and the interrelation between Information Technology (IT), Information and Communication Technology (ICT), and e-Government. Moreover, the literature review immensely expounds on the implementation studies; the complexities associated with the different approaches to implementation are presented to bring forth the origin and to substantiate the interlinkages between the variables of the 7-C Protocol Instrument while also demonstrating an integrated approach to policy implementation. This research also provides an overview of various legislative frameworks that govern e-Government initiatives in South Africa, from the Constitution of the Republic of South Africa (1996) as the foundation, to the Government Communication policy (2018). The ICT policy review process highlights the government's commitment to reviewing regulations to enhance the ICT industry's socioeconomic contribution. This review process emphasises clear objectives, institutional capability evaluation, high-level commitment, stakeholder engagement, and stakeholder coordination, which the researcher recognised to be aligned with Cloete et al. (2018) 7-C protocol instrument. This research particularly identifies the formulation of the ICT Policy as an example of implementation success due to the nature of its implementation. The study adopted a qualitative research methodology encompassing empirical and non-empirical studies. The data collection included a case study based on the DWS strategic reports and three categories of interview schedules. The population that was studied included employees involved within the DWS Water Use Authorisation (WUA) component nationally, from the Executives/Senior managers, Technical Support and System Developers, Technical Officials (Specialists/Scientists/Environmentalists) and Administrators who are the end-users of E-WULAAS. The research utilised a deductive thematic analysis method by applying Cloete et al. (2018) 7-C Protocol instrument to analyse the data to acquire in-depth knowledge on the implementation of e-Government at DWS. The analysis and findings reveal several factors hindering the implementation success, such as the lack of adequate human resources and IT infrastructure to handle and integrate big data, the digital divide, the absence of change management processes and consequences management, and the silo approach frequently adopted when implementing online systems. Thus, recommendations such as ensuring adequate resource allocation, bridging the digital divide, and institutionalising Monitoring and Evaluation (M&E) to enhance and strengthen oversight, amongst others, were made. This research highlights that it is crucial to acknowledge the complexities of implementation and for policy and programme implementers to completely comprehend the implementation dynamics and the interlinkages of the critical variables before undertaking an implementation process.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.Master

Conceptual modelling of microplastic fragmentation in the marine environment

Henri, J. T. 2025. Conceptual modelling of microplastic fragmentation in the marine environment. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/22027e8e-3a00-45b1-b9f1-d68cc7a0abf2Thesis (MEng)--Stellenbosch University, 2025.ENGLISH ABSTRACT: Under the overarching context of the formation, fate, and transport of microplastic in the marine environment, the primary aim within the scope of this project was to develop a conceptual mathematical model describing plastic degradation within the marine ecosystem. The first objective of this study was to investigate the various degradation routes for plastic and the relationship between photo-oxidation and mechanical breakage. The second objective was to compare plastic degradation (due to photo-oxidation followed by mechanical breakage) rates in various environments such as urban areas, simulated by ceramic abrasion; beach environments, simulated by fine particulate sand abrasion; and ocean surf environments, simulated by wet sand abrasion in a rotating vessel. The third objective was to develop a conceptual mathematical model for the photo-oxidation mechanical degradation pathway. The fourth objective was to fit model parameters to experimental data through mathematical back-calculation techniques. The objectives of this study have been achieved by firstly studying plastic degradation mechanisms; secondly, designing a two-factor experiment to study the combined effect of photo-oxidative and mechanical abrasion upon plastic degradation characteristics; and thirdly, carrying out batch abrasion-fragmentation experiments to obtain microplastic breakage data to investigate the extent to which prior exposure of plastic particles to ultraviolet radiation affected its breakage characteristics. Fourthly, with experimental data generated, models were developed which fit the associated parameters and describe the breakage characteristics. To achieve the objectives stated, an ultraviolet radiation chamber was built with a capacity of 1000 g plastic and irradiation intensity of 1000 W/m2. Pretreatment of the plastic for abrasive fragmentation studies was carried out in the irradiation chamber, where accelerated photo-oxidative degradation mechanisms were induced for durations of 72 − 192 hr to understand breakage processes and rates of a plastic particle starting size class of 2800−4000 μm. A rotary abrasion vessel (D = 200 mm; L = 270 mm) was designed to be operated between 66 − 75 rpm on rollers driven by an electric motor. Thereafter, three different environmental attrition-fragmentation conditions were investigated in the rotary abrasion vessel with incrementing time intervals. Plastic mechanical fragmentation on pathways, rocks, and pebbles was approximated by investigating the breakage of particles when using ceramic milling media in the mill. Thereafter, finer fragmentation plastic experiences on the shoreline were simulated in the rotating vessel with sand as abrasion media. Finally, an abrasive environment in the surf was simulated in the rotating vessel causing the rupture of brittle plastic particles colliding with sand particles in the water and sand mixture. Analytical, average, and differential model solutions were developed for simulation conditions in the coastal environment. First-order differential equations were parameterised to model the breakage of the plastic and microplastic formation with respect to abrasion time. A key finding was the onset of plastic brittleness that occurred at an ultraviolet treatment time of approximately 70 hr, leading to mass loss in all the simulated environments. In the ceramic environment, with ultraviolet exposure times of 120 hr, it was found that polypropylene pellets in size class 2800−4000 μm loses 80 % of its mass to lower size classes within 32 min of abrasion, resulting in 74.4 % of particles reporting to the 2350−2800 μm size class and the balance to size class 0−2350 μm. Thus, mass loss from 2350−4000 μm size class is 5.6 %. Concatenation of sieve sizes into lower 0−1700 μm and upper 1700−4000 μm classes revealed a mass loss of 5.96 % within 32 min and 8.75 % in 136 min. Mathematical modelling yields selection function S = 0.1857ln(tnUV) + 0.1756. In comparison, similar plastic particles with a UV-T of 120 hr degraded with a 8.36 % mass loss after 72 hr of abrasion in the sand environment in repeatability tests. Analysis yields a selection function S = 0.0023ln(tnUV) + 0.0026. While in the sand and water environment, plastic loses 14 % of its mass after 120 hr of ultraviolet treatment and 120 hr of abrasion in a sand and water abrasion environment under the irradiative-abrasive conditions simulated. Analysis yields a selection function S=0.001ln(tnUV)+0.0015.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar.Master

Proton single-event effects tolerance testing of a vision processing unit for satellite use

Badat, S. 2025. Proton Single-Event Effects Tolerance Testing of a Vision Processing Unit for Satellite Use. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/ab66f6c1-dc89-48a2-ba4c-37f9d0e09a07Thesis (MEng)--Stellenbosch University, 2025.ENGLISH ABSTRACT: This thesis investigates the Single Event Effects (SEE) susceptibility of the Intel Movidius Myriad X Vision Processing Unit (VPU) when exposed to 66 MeV protons. The research makes use of an industry-standard computer vision model and a custom neural network designed specifically for SEE detection to perform testing with only API-level access to the device. Testing was performed using the YOLOv7-tiny object detection model and a custom single-layer network (PlusOne) designed to trace error propagation. The Myriad X exhibited SEE cross-sections in the range of 10−11 to 10−9 cm2 , with functional failure occurring at approximately 65.77 krad(Si). While numerous Single Event Upsets (SEUs) were observed, post-processing techniques proved effective at filtering many errorinduced predictions. Analysis of recurring errors provided insight into potential firmware vulnerabilities to SEE. The research also reveals opportunities for SEE-aware neural network design, suggesting that architectural modifications to networks could enhance radiation tolerance.AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die sensitiwiteit vir Enkelgebeurteniseffekte (SEE) van die Intel Movidius Myriad X Vision Verwerkingseenheid (VPU) wanneer dit blootgestel word aan 66 MeV protone. Die navorsing maak gebruik van ’n industrie-standaard rekenaarvisie-model en ’n persoonlike neurale netwerk wat spesifiek ontwerp is vir SEE-deteksie om toetsing uit te voer met slegs API-vlak toegang tot die toestel. Toetsing is uitgevoer met die YOLOv7-tiny objekdeteksiemodel en ’n persoonlike enkel-laag netwerk (PlusOne) wat ontwerp is om foutpropagasie na te spoor. Die Myriad X het SEE-deursnee-waardes tussen 10−11 tot 10−9 cm2 getoon, met funksionele mislukkings wat plaasgevind het by ongeveer 65.77 krad(Si). Terwyl talle Enkelgebeurtenis-omkerings (SEUs) waargeneem is, het na-verwerkingstegnieke effektief geblyk om baie fout-ge¨ınduseerde voorspellings uit te filter. Analise van herhalende foute het insig gebied in potensi¨ele firmware-kwesbaarhede vir SEE. Die navorsing onthul ook geleenthede vir SEE-bewuste neurale netwerkontwerp, wat daarop dui dat strukturele aanpassings aan netwerke stralingstoleransie kan verbeter.Master

A Hybrid Deep Learning based Algorithm for Gamma Spectroscopy Analysis

Thesis (PhD)--Stellenbosch University, 2025.Buckton, C. 2025. A Hybrid Deep Learning based Algorithm for Gamma Spectroscopy Analysis. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/8db1d4f0-1872-4d33-87fd-8b3527a44704There exists a select group of unstable nuclei which undergo radioactive decay by emission of highly-energetic photons or γ-rays. An effective tool for analysing γ-emitting radioactive sources, γ spectroscopy is a common experimental technique used in high-energy physics and environmental monitoring of radiation. Analysis of various naturally-occurring radionuclides and their decay products through γ spectroscopy has provided a practice for health and safety regulation. It is a process which has seen a large amount of improvement in efficiency and optimization over the past decade. This has often been partly due to developments in detection and analysis which build upon existing experimental methods. Recently, there have been developments in machine learning based approaches, for automated and efficient detection and radioisotope "fingerprinting". That is, these methods make use of the characteristic spectra measured from radioactive isotopes to identify them. These methods have commonly consisted mostly of a computational component, a deep-learning algorithm known generally as a deep neural network (DNN), which is trained on a representative dataset of energy spectra from different isotopes, often simulation-based. Becoming increasingly more efficient, a type of network called convolutional neural networks (CNNs) are most prominent in this application, due to their ability to effectively learn useful features from high-quality data and being able to classify or recognise radioactive species with very good accuracy. However, a challenge which can occur is when there are multiple sources present in a sample of data, as opposed to just a single source, where the accuracy of the network will often decrease as the number of sources increases. Additionally, developing a CNN model which is computationally efficient, but also accurate and robust to noise and other environmental influences can be difficult.Doctora