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The chiton fauna (Mollusca: Polyplacophora) of South Africa
Get PDFChitons are a diverse class of molluscs inhabiting marine waters and constitute a significant, yet relatively underexplored group of invertebrates in South Africa. Over the past three decades, taxonomic research has resulted in a pronounced increase in the description of regional chiton species, with the result that the most recent (1985- 2006) series of global monographs on chitons by Kaas and Van Belle now cover only 22 of the 50 chiton species currently recognised from the region, highlighting the need for a new synthesis of the fauna. This dissertation documents all the known chiton species inhabiting South African waters and adds new records of species that were previously undocumented. The study identifies an additional eight species new to the region from South African museum collections. A remarkable endemism is found in this group, with 46% of chiton species in South Africa found nowhere else. Of these endemics, 34% can be found only on the South Coast. The dissertation also includes a complete species list of the region and a user-friendly field guide that highlights key taxonomic features of the region's chiton species, with an accompanying binomial key for identification of species. It includes photographs and illustrations to aid in species identification, as well as a distribution map for each species. Chitonida is the largest order found in the region, with Acanthochitonidae, Chaetopleuridae, Chitonidae and Ischnochitonidae as four of the largest families in the region. Leptochiton is the most diverse genus in the region, also indicating a relatively high species richness in deeper waters. Chiton species of the region exhibit a greater species richness to the east and a higher endemicity to the South, with 56% of the species found on the South Coast endemic, though there seem to be a low intensity of collection on the Eastern coast. Although this dissertation adds significantly to the regional chiton fauna, further sampling and research is needed to comprehensively resolve and describe all the species and to assess their conservation status, given the anthropogenic threats these species face, including habitat destruction and possible unethical and unregulated collections
Exploring emerging market multinational enterprises' divestment from emerging markets
Get PDFWhile many studies have examined the internationalisation of multinational enterprises (MNEs) into emerging markets, there is comparatively little research on their divestment from these markets. Additionally, most studies on foreign divestment focus on multinational enterprises from developed markets rather than emerging market multinational enterprises (EMNEs), leaving a gap in the literature on EMNEs' divestment from emerging markets which this research aimed to explore. This dissertation discusses how and why emerging market multinational enterprises (EMNEs) divest from emerging markets. Specifically, this research explores the antecedents of divestment, focusing on the divestment motives, decisions, and strategies of South African MNEs that operated in Nigeria in order to address the main overarching research question. Consequently, South African MNEs are the primary focus of EMNEs, and Nigeria is the focal emerging market for this research. This research employed a qualitative, inductive, and exploratory approach, utilising multiple case studies of South African MNEs that were operational in Nigeria before subsequently divesting. The research findings of this study were based on semi-structured interviews, with the majority of the interview participants being from the South African MNEs, along with two additional subject matter experts. To obtain the overall research findings from these interviews, the data was analysed through manual thematic coding, without the use of any coding software. Additionally, this research incorporated triangulation with secondary research in order to verify and add depth to the findings from the interviews. This study views the results of the reasons for divestment from three perspectives: host country turbulence and institutional voids leading to divestment, home country's institutional weakness influencing divestment and firm-related challenges influences on divestment. In conjunction with this, it then separately discusses the divestment approaches or strategies adopted. The findings of this study contribute to and have implications for academia, EMNEs, and stakeholders involved in international business operations
The impact of the SARS-COV-2 pandemic on maternal mortality in a South African Metropole (2020-21)
No full textBackground: During the COVID-19 pandemic there was a notable increase in maternal deaths across South Africa. Pre-pandemic, the Western Cape Province had made significant strides towards reducing maternal mortality. However, this progress was reversed in the pandemic period despite a relative protection of maternal care services. The biological impact of SARS-CoV-2 may not be the sole reason for the increase in mortality. Therefore, we aimed to evaluate the relative change in the maternal death rate for non-SARS-CoV-2-related deaths intra-pandemic versus pre-pandemic in 2019. Methods: We conducted a retrospective cohort study involving all pregnant women with a pregnancy outcome enumerated in the Provincial Health Data Centre, in the Metro-West region of Cape Town from 1 January 2019 – 31 January 2022. Cause of in- facility maternal death and relationship to SARS-CoV-2 infection was determined by folder review. We used Interrupted Time Series (ITS) analysis to assess the impact of the pandemic period on non-SARS-CoV-2 causes of maternal mortality. Maternal characteristics reviewed included HIV status and the proportion of maternal deaths occurring in persons living with HIV were also explored. Results: Over 98 000 women were included with 68 deaths reviewed. The ITS model (p =0.01) revealed that the pandemic was associated with a step increase of 3.12 (-1.66;7.9) in maternal mortality rate for non-SARS-CoV-2 related deaths following the start of the pandemic. This impact was sustained with an attenuation in the maternal mortality rate reduction over time from -0.56 pre-pandemic to -0.12 intra-pandemic. Folder review of deaths revealed an increase in opportunistic infections as a cause of death relative to pre-pandemic. Conclusion: Whilst maternal healthcare services were largely protected from service disruptions during the COVID-19 pandemic, there was a reversal of some of the progress made in reducing non-SARS-CoV-2 maternal deaths in prior years. An increase in opportunistic infections and an attenuation of the decline in maternal death rate suggest that optimising maternal health requires the well-functioning of the entire healthcare ecosystem. The indirect impact of health threats, and our responses thereto, need to be strongly considered in future management strategie
Effects and resource implications of one anastomosis gastric bypass procedure in comparison to sleeve gastrectomy and roux n y gastric bypass in obese patients: A systematic review and meta-analysis
Get PDFBackground One anastomosis gastric bypass (OAGB) is a proposed alternative to Roux n Y gastric bypass (RYGB) and sleeve gastrectomy (LSG) which are the main bariatric operations in many centres. It is a restrictive and malabsorptive weight loss surgery thought to be simpler, having a small learning curve and shorter intraoperative time. However, its effects and safety compared to other methods remains uncertain. Objectives We aim to evaluate the available evidence from randomised controlled trials (RCTs) on effects, resource input and safety of OAGB in comparison to LSG and RYGB in obese adults and children, with a view of ascertaining the optimal technique especially in resource constrained environments. Methods We searched MEDLINE (PubMed); Embase (Ovid); Central Register of Controlled Trials (CENTRAL, Cochrane Library); Web of Science Core Collection, specifically Science Citation Index Expanded, Social Sciences Citation Index, Conference Proceedings Citation Index (Clarivate); CINAHL (EBSCOHost); Scopus; LILACS (Virtual Health Library) from Jan 2001 when OAGB was first described to August 2021. We identified all RCTs regardless of language or publication status using two search strategies, the primary strategy relating to effects and safety and the complementary strategy for health economic evaluations. We included all RCTs with adults or children with body mass index (BMI) greater than 40 or greater than 35 with comorbidities comparing OAGB to either LSG or RYGB with effects, safety, or resource implication data. Two authors independently identified the studies for inclusion, collected the data and assessed the risk of bias (ROB). We performed the meta-analyses using the Review Manager 5.4. We calculated the risk ratio (RR) for dichotomous outcomes and mean difference (MD) for continuous outcomes with 95% confidence intervals and used the random - effects model. Where meta-analysis was inappropriate or not possible a narrative synthesis was given. We used the Cochrane ROB-2 tool to assess for ROB. We used GRADE to assess the certainty of evidence for the outcomes in the summary of findings. Results From 7 271 studies we included 34 studies; 10 being published data,12 conference abstracts and 13 ongoing trials one of them with preliminary results. All participants were adults. None of the studies in the review reported on cost of the procedure or any surgery related mortality. OAGB vs LSG Total of 147 patients in the OAGB arm were compared to 146 in the LSG arm in 5 included studies (1 study had 3 publications at 1, 3 and 5 years). OAGB results in little or no difference in comorbid resolution compared to LSG for all outcomes except hypertension and diabetes at 5 years where OAGB likely results in large increase in complete diabetes resolution; RR 1.5 (1.10, 2.04). and hypertension RR 1.51 (1.03, 2.19), low evidence from one trial. OAGB likely results in large increase in estimated weight loss percentage (EWL%) consistently up to five years where EWL% is -9.34 (- 16.39, -2.29), 5 RCTs, 635 participants. Operation time is likely longer compared with LSG MD 19.04 minutes (6.49%, 31.6%), 3 RCTs, 304 participants, moderate certainty evidence. OAGB may result in an increase in bile reflux RR 1.5 (0.58, 3.88) though the evidence remains uncertain. OAGB may result in more malnutrition compared to LSG RR 2.09 (0.94, 4.63), 3 RCTs, 234 participants, low certainty evidence. Recidivism was only in 3 patients in 2 RCTS after LSG compared to OAGB, moderate certainty evidence of little or no difference. OAGB likely results in slightly better quality of life scores (QOL) including comorbidities compared to LSG up to 5 years. At 5 years, QOL is likely better after OAGB with or without comorbidities. OAGB vs RYGB Two hundred and forty-four participants had OAGB vs 254 in RYGB in 5 included studies. OAGB may result in little to no difference in comorbid resolution at 1 year: complete diabetic remission RR 0.86 (0.67, 1.10), 2 RCTs moderate certainty evidence. OAGB may result in increased EWL% compared to RYGB MD -4.93% (- 7.88%, -1.99%), 5 RCTs, 575 participants. Operation time is likely shorter with OAGB compared to RYGB MD -34.3 (-45.76, - 22.84) minutes with little or no difference in length of stay. OAGB likely results in large increase in bile reflux compared to RYGB RR 17.25 (3.13, 94.97), 3 RCTs, 322 participants with 1 report of intestinal metaplasia in the OAGB arm. The evidence is very uncertain from 2 RCTs, 128 participants about the effect of OAGB on malnutrition rates compared to RYGB: RR 2.28 (0.13, 40.45). There is little or no difference in QOL and reoperation rates compared to RYGB. Conclusion Except for weight loss and operative times, the evidence remains uncertain comparing the effects and safety of these 3 methods. From the limited data we have, OAGB attains as good outcomes as RYGB which is the preferred option in most setting, with additional significantly better weight loss. Using surrogates of theatre time and number of staples used OAGB appears to save time and to be a cheaper option than RYGB. However, there are still concerns of likely increase in bile reflux and no evidence of effect on malnutrition after surgery. More RCTs with larger sample sizes in low-income areas are needed to explore these outcomes further. More long-term studies will explore the possibility of development of gastric cancer. None of the studies reported on cost of the procedures to inform decision making in low-income area
Thermodynamic analysis and performance evaluation of PTC receiver with external annular fins
Get PDFSince the advent of industrial revolution, the main source of energy has been fossil fuels, and it has resulted in adverse environmental impacts. With the depletion of fossil fuels and greenhouse effect, the utilization of solar energy has attracted increasing attention owing to the distinct advantages, including cleanliness, sustainability, inexhaustibility. This has motivated extensive research and innovation to foster a shift to renewable energies, of which concentrated solar power presents itself as the most promising option. Given the unrivalled abundance of solar energy, the source has a potential to meet a substantial portion of future energy demand. This research investigates the influence of external annular fins on the thermal and thermodynamic performance of parabolic trough collector receiver. The objective is achieved by developing thermal and fluid flow model with geometry of varied fin length and fin numbers in different range of Reynolds number and inlet temperature. The model was implemented in commercial ANSYS Fluent software and validated with existing literature—Forristall (2003) that yielded significant agreement. The results showed that introduction of fins increases thermal efficiency of the receiver. An increase of 2.26 percent for Tin = 350 K, 2.21 percent for Tin = 400 K and 2.22 percent for Tin = 500 K was recorded for varying Reynolds numbers. Also, the thermal efficiency in t = 10 mm was higher than t = 5 mm with values in the range of 88 - 90.5 percent while smooth receiver fell in the range of 84 - 86 percent. Additionally, thermal enhancement factor showed slight improvement. i What's more, exergy efficiency showed an improvement with introduction of fins. It was noted that the enhancement increased the exergy efficiency by 2.44 percent for Re = 5000, 2.30 percent for Re = 10000, and 2.30 percent for Re = 20000. Similarly, entropy generation reduced with fins variations. The entropy generation rate decreases with increasing fin length. The smooth absorber tube has the highest entropy generation rate whereas the absorber tube with largest fin length has the lowest. Heat transfer irreversibility has been found to be dominant at lower turbulence and variation of annular fin length and numbers reduces it. In summary, the introduction of passive enhancement of external annular fins was shown by the results to be thermally and thermodynamically favourable, regardless of the degree of improvement. Therefore, this enhancement technique can be combined with other methods to design a high performing PTC receiver—an endeavour that will contribute to implementation of a stand-alone reliable PTC power plant
Drafting sex workers' human rights: using decriminalisation to combat gender-based violence faced by sex workers
Get PDFRates of gender-based violence (“GBV”) are rapidly growing in South Africa, which has come to be known as the “rape capital” of the world. 1 This violence is indiscriminately perpetrated against women across the country, including sex workers who are often victim of heinous acts of GBV due to their limited protection under the law and stigmatised role in society. The legal responses to sex work, namely legalisation, criminalisation, or decriminalisation, have become an increasingly discussed topic across the world due to a heightened understanding of the complex challenges sex workers face. While it is currently illegal to buy or sell sex in South Africa, if the Criminal Law (Sexual Offences and Related Matters) Amendment Bill 2022 (“the Bill”) is passed, South Africa will become only the third country in the world to fully decriminalise sex work. The draft Bill proposes the removal of the criminalisation of buying and selling of sex and the clearing of criminal records of those who have been prosecuted for buying or selling sex. This dissertation is therefore, aimed at critically analysing how decriminalising sex work in South Africa by way of enacting the draft Bill can aid in reducing sex workers' vulnerability to experiencing GBV, specifically by affording greater protection to sex workers and eradicating the dangerous stigma around sex work. This dissertation therefore undertakes to investigate how the criminalisation of sex work disproportionately affects sex workers by exposing them to rampant levels of abuse, sexual violence and police brutality, under the umbrella of GBV. Therefore, it further aims to establish how the criminalisation of sex work correlates directly with the violation of numerous sex workers' human rights. In considering how effective South Africa's current legal response to sex work is, it is pertinent to analyse our international and domestic obligations to protect women against violence and violations of their human rights, specifically identifying the position of sex workers amongst these protective forces. In bolstering attempts to protect the rights of sex workers and give effect to the intentions of the Bill of Rights and South Africa's international obligations, the findings of this dissertation ultimately reveal why it is of the utmost importance that government decriminalise sex work and enact the Bill without undue delay. Further recommendations will be provided to work in conjunction with the draft Bill to assist the safety of sex workers in South Africa
Towards the development of plant-made PsVs as potential delivery vehicles for therapeutic HPV vaccines
Get PDFInfection with human papillomavirus (HPV) is the leading cause of cervical cancer, the fourth most common cancer in women globally. Cervical cancer results in an estimated 604,000 new cases and 342,000 deaths each year, with the majority of these cases reported in sub-Saharan Africa. HPV-16 is a high-risk oncogenic subtype and, along with HPV-18, is associated with >70% of all cervical cancers. While current vaccines can prevent infection with high-risk HPVs, they cannot induce regression of persistent infections, thus the development of vaccines that function therapeutically is required. DNA vaccines are ideal candidates for therapeutic treatment; however, naked DNA vaccines are associated with ineffective presentation to antigen presenting cells (APCs). This limitation can be overcome by using pseudovirions (PsVs) as vaccine delivery vehicles. HPV PsVs are highly immunogenic synthetic viral particles consisting of L1 and L2 capsid proteins, which self-assemble to package pseudogenome DNA. Pre-existing immunity to high-risk HPVs through natural infection and vaccination, however, preclude their use as delivery vehicles for DNA vaccines. The development of non-human papillomaviruses (PVs) PsVs for gene delivery is a novel alternative. PV PsVs are conventionally produced in mammalian cells. However, plants have demonstrated potential as an alternative platform for rapid PsV production due to their scalability and cost-efficiency. Therefore, the aim of this study was to investigate plant-based production of bovine papillomavirus 1 (BPV-1) PsVs encapsidating a HPV-16 therapeutic DNA vaccine candidate, and to assess their infectivity in mammalian cells. Initially, strategies to optimise Agrobacterium-mediated transient expression of BPV-1 L1 and L2 capsid proteins in Nicotiana benthamiana were explored. Approaches such as an increased acetosyringone concentration for recombinant Agrobacterium induction, a heat-shock treatment of post-infiltrated plants, and an extended in planta maturation were investigated. A pseudogenome encoding secreted embryonic alkaline phosphatase (SEAP) was co-infiltrated with BPV-1 L1- and L2-encoding expression vectors. L1 protein expression and particle assembly were confirmed with western blotting and transmission electron microscopy (TEM) respectively. However, no SEAP expression was observed following infection of HEK293TT cells with the plant-made particles and none of the strategies investigated were conclusively found to increase BPV-1 PsV yield. Several geminivirus-derived self-replicating reporter plasmids encoding a HPV-16 shuffled E7 (E7SH) sequence were constructed using In-Fusion cloning. These constructs were co-expressed in N. benthamiana with expression vectors encoding BPV-1 or HPV-35 L1 and L2 proteins. HPV-35 was chosen as it has been shown to encapsidate a Zera®E7SH DNA vaccine in plants for delivery to mammalian cells in vitro. Following purification, rolling circle amplification (RCA) analysis showed successfully encapsidation of the E7SH-based pseudogenomes within the plant-made PsVs. However, TEM showed that PsV yields were low and no E7 expression was observed following infection of HEK293TT cells with the plant-made PsVs. These results indicated that encapsidation efficiency of PsVs produced in plants is low. BPV1 and HPV-35 PsVs were also produced in HEK293TT cells and comparative analyses with plant-made particles revealed that, while the pseudogenomes were successfully encapsidated in the PsVs produced in both systems, only the HEK293TT-made PsVs effectively delivered their packaged DNA into mammalian cells. These findings demonstrate the ability of PsVs to self-assemble and encapsidate pseudogenome DNA in planta while also revealing potential limitations of plant-based PsV production. For plant-made PsVs to reach their potential in gene delivery, further optimisation and characterisation of plant-based PV PsV expression is required
Quantifying polyphosphate energy for modelling of polyphosphate accumulating organisms behaviour in anaerobic digestors
Get PDFThis study investigated the behaviour of polyphosphate accumulating organisms (PAOs) in linked activated sludge-anaerobic digestion (AS-AD) systems, with particular focus on quantifying polyphosphate (PolyP) energy and its role in PAO metabolism. The study was motivated by observed discrepancies between theoretical predictions and experimental observations in AD systems treating phosphorus-rich waste activated sludge, particularly regarding pH predictions and mineral precipitation patterns. The research employed a University of Cape Town membrane bioreactor activated sludge (UCT MBR AS) system to cultivate an enriched PAO culture. This approach successfully achieved high PAO concentrations, enabling detailed investigation of PAO metabolism and stored PolyP levels. The experimental methodology combined operational data from both AS and AD systems with comprehensive chemical analyses and mass balance validations. Two conceptual models were evaluated for PolyP release stoichiometry in AD: one incorporating PHB formation with PolyP energy utilization, and another assuming direct PolyP release without PHB formation. The comparison aimed to elucidate energy transfer mechanisms between AS and AD systems. The research demonstrated successful cultivation of an enhanced PAO culture in the AS system, achieving significant phosphorus cycling capabilities and robust metabolic activity. The investigation of PAO behaviour in AD environments revealed complex interactions between biological processes and chemical equilibria. The experimental results provided strong evidence supporting the hypothesis that PAOs utilize stored PolyP energy for PHB formation in AD environments. This was particularly evident in pH and alkalinity measurements, which aligned more closely with the model incorporating PHB formation. Significant findings included the observation of rapid PolyP release within initial digestion days, complex precipitation dynamics, and marked differences between total and dissolved metal ion concentrations. The research validated the role of PolyP as an energy carrier between AS and AD systems, while also highlighting limitations in current precipitation kinetics modelling approaches. The study's findings have important implications for understanding PAO metabolism and energy utilization in wastewater treatment processes. The research contributes to improved prediction of AD performance when treating phosphorus-rich sludge and offers insights for optimizing biological nutrient removal systems. Future research directions were identified, particularly regarding molecular-level understanding of PAO metabolism and the development of enhanced precipitation models. This investigation advances our understanding of biological phosphorus removal processes and provides practical guidance for improving wastewater treatment system design and operation. The findings support more accurate modeling approaches and highlight the importance of considering energy transfer mechanisms in linked AS-AD systems
Condition assessment methods for prestressed concrete railway sleepers: feasibility for South African applications
Get PDFConcrete sleepers are a key component of railway systems, with estimates showing between 20 million to 35 million currently installed within the South African railway network. The condition assessment of concrete sleepers in South Africa poses a challenge for two main reasons: the scale at which condition measurements need to be conducted, and the poor access to sleepers within the ballast structure. To assess feasibility of concrete sleeper assessment methods, the quality of technical results was reviewed to ensure the information required for long-term lifecycle needs of concrete sleepers can be produced and that the risk associated with failures of critical defects are mitigated. The work established in the literature review was consolidated through a three-phase methodology to provide results for the assessment. This involved a Failure Mode and Effect Analysis (FMEA) that measured how well each of the methods can detect the failure modes, and then benchmarked the condition assessment methods against similar technology currently in use within the South African network. A test for defect relevance checked that the defects identified in the literature were relevant for South African applications and allowed for further categorisation of criticality. Longitudinal cracking and vertical cracks at the rail seat were found to be the most critical defects required to be detected by concrete sleeper condition assessment methods. Vehicle-mounted ultrasonic echo and vehicle-mounted imagining technology methods both showed good technical results from the FMEA, showing better quality information on sleeper condition than current methods in use. But only the vehicle-mounted imaging scored a residual profile value below the recommended technical threshold, and showed to benchmark cost, lead time and operational factors in line with current methods. Consequently, vehicle-mounted imaging is the most feasible option for concrete sleeper condition assessment for South African applications. Sleeper body abrasion cannot be well detected through any methods reviewed and will require further study of methods before visual inspections of this defect can be improved upon. Failure modes of concrete sleepers due to prestressing steel corrosion were unclear and further testing should be done to define what early-stage cracking displays to accurately predict the end of the useful life of a sleeper
Developing a critically inclusive study of religion
Get PDFThe scientific, or secular, study of religion is a relatively new endeavour, and has faced multiple obstacles over the course of its development. The primary challenge has consisted of the need to distinguish the secular study of religion from the theological study of religion. The commitment to exclusive humanism has played a foundational role in this process. This form of humanism developed during Europe's colonial era and helps to cement the modern secular worldview. That said, there are critical material scholars who attempt to move beyond the strictures of their colonial inheritance. New models for examining the materiality of religion have followed the integration of new-materialist theory into critical religion research. Along with new-material approaches, the way opens to posthuman studies of religion. This allows scholars to critically engage with the outdated and racialised categories that emerged in 19th century humanist discourse. However, the domain of posthuman studies is not altogether free of colonial baggage, and this shows in the lack of black and indigenous voices in the field. Both the material study of religion, and the posthuman study of religion lack a coherent engagement with indigenous worlds and therefore remain within modern colonial boundaries. These exclusions correlate with the unexamined commitment to secular rhetoric within the modern academy. As a modern construct, the secular domain makes absent the world-making practices of indigenous collectives and renders them invisible within critical discourse. To remedy this, I point to the work of nonmodern scholars, who present alternate ontologies and epistemologies that require attention should the critical study of religion wish to develop into an inclusive domain of academic enquiry