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Estimation of the eye lens doses in a catheterization laboratory from available image parameters
No full textBackground and objective: New data on eye lens dosimetry supports the theory that the threshold of radiation-induced cataracts could be substantially lower than previously believed with some investigators arguing that cataracts could be classified as a stochastic rather than a deterministic effect. Based on these new data, the International Commission on Radiological Protection (ICRP) has reduced the occupational eye lens dose limit from 150 mSv to 20 mSv averaged over a defined period of 5 years, with no single year exceeding 50 mSv. The new reduction in the annual dose limit will have considerable implications particularly in high exposure environments such as interventional cardiology and radiology. It is therefore imperative that strategies for effective dose reduction, radiation protection, eye dose monitoring, and dosimetry be implemented in countries that have already adopted the new eye dose limit. The main aim of this study was to develop methods that can be applied to estimate eye dose equivalent from the available imaging parameters and whole-body equivalent measured over the lead apron at the chest level. The study also aimed to establish a method to estimate eye lens dose based on the workload of interventionalists. Material and methods: The study included four interventional cardiologists. A total of 127 procedures were performed in a period of three months. The procedures were categorised into diagnostic (CA) and therapeutic (CA+PCI) procedures. During these procedures, two different active dosimeters were used to measure scatter dose (one attached on the canthus of the protective eyewear to measure eye lens dose (ELD) and the other at the chest level to measure whole-body dose) to the cardiologists. The dose area product (DAP), air kerma (Ka,r), fluoroscopic time, total cine images were recorded after every procedure. The efficacy of the protective eyewear used at Universitas Hospital was evaluated in a separate study. Results: Average eye dose per CA and CA+PCI procedures were 195.1±112 and 391.8±202.9 µSv, respectively. The average dose per procedure obtained by combining all the monitored procedures was 250.9±168.3 µSv. The minimum workload necessary to exceed the annual eye lens dose limit calculated using an equation established in this study was 80 procedures. The dose reduction factor of the protective eyewear was ~2. Applying this factor increased the minimum procedures necessary for a doctor to exceed the limit to 160 procedures per year. Excellent correlation was found between ELD and DAP (R2 = 0.78). Excellent correlation was also found between ELD and Ka,r (R2 = 0.72). A poor but significant correlation was found between ELD and chest dose (R2 = 0.45). Three methods based on the ratios of ELD to DAP, Ka,r and chest dose were established. The calculation error using the methods based on DAP and Ka,r was ±20%. The respective calculation error was ±37% using the method based on chest dose. Conclusion: The accumulated eye dose of interventional cardiologists working at the Universitas Hospital can easily surpass the newly set annual eye lens dose limit after performing relatively low numbers of interventional procedures. The high average dose per procedure reported in this study highlights immediate need for implementation of radiation optimization strategies to mitigate the risk of radiation-induced cataracts. This is the first study in South Africa to establish methods that can be used to estimate eye lens doses at any time. More research is needed in the South African context to further investigate eye lens dose in interventional suits. This will allow for comparison of results obtained at different institutions and improvement in accuracy of estimation methods
The profile of genetic mutations in pheochromocytomas and paragangliomas in South African patients
No full textBackground: Pheochromocytomas (PCCs) are rare neoplasms of the adrenal glands. Extraadrenal pheochromocytomas, or paragangliomas (PGLs), most commonly involve the carotid body and middle ear. Both germline and somatic variants are associated with their pathogenesis, and identification of a specific genetic variant guides clinical management in patients and their families. The genetic heterogeneity of PCCs/PGLs is distinct, creating the possibility of personalized, genomics-driven therapy. Next-generation sequencing allows massive parallel sequencing of all genes of interest in a single, cost-effective run. Internationally, extensive research has been done regarding the genetic make-up of PCCs/ PGLs, and the genes most commonly involved include SDHB, SDHD, RET, and VHL. Aim: To describe the genetic variants in PCCs/PGLs in the South African population. Methods: A retrospective study was performed. Ninety eight of the most recent cases with sufficient tissue available in wax blocks were included. Manual DNA extraction and subsequent DNA sequencing was performed, and 16 genes of interest were assessed for possible variants. These included EGLN1 , EPAS1 , FH , HRAS , IDH1 , KIF1B , MAX , NF1 , RET , SDHA , SDHAF2 , SDHB , SDHC , SDHD , TMEM127 and VHL . Results: Thirty one of the 98 cases were sequenced. In the remaining cases the DNA quality was inadequate. Ninety three variants were detected with 32 synonymous variants, 54 missense variants, and 7 truncating variants. Nine pathogenic or likely pathogenic variants were identified in total, involving the NF1, KIF1B, RET, SDHB and TMEM127 genes. Most variants identified were predicted benign, likely benign and benign variants or variants of unknown significance. Conclusion: The profile of pathogenic or likely pathogenic variants identified in this study differs somewhat from that described in the literature with NF1 and KIF1B most commonly involved. In addition, no pathogenic SDHD or VHL variants were found in this study. However, the number of patient’s is small and additional data are required to determine the true genetic profile in South African patients.University of the Free State, Department of Surgery Research Fun
The prevalence of aniridia and associated visual and ocular complications among learners in schools for the visually impaired in central South Africa
No full textIntroduction Aniridia is a rare, sight-threatening ocular disorder characterised by partial or complete absence of the iris. It can affect multiple ocular structures and lead to visual complications. According to our knowledge, there is currently no recent published research on aniridia in the South African population, thus it would be beneficial to investigate the prevalence of aniridia and describe the ocular and visual complications in South Africa. Therefore, the aim of this research was to determine the prevalence of aniridia among learners in visually impaired schools in central South Africa (Free State and North West) and to describe its visual and ocular complications. In order to achieve the aim, the number of participants that had partial and complete aniridia was determined using an ophthalmoscope. Thereafter, the visual and ocular complications in participants with aniridia were determined. Methods A prospective descriptive study was conducted on learners in three visually impaired schools in central South Africa. A total of 117 consenting learners were screened with an ophthalmoscope to determine the presence or absence of aniridia and only the participants identified with aniridia were further examined. The visual acuity of the participants with aniridia was determined using a logMAR visual acuity chart, the refractive error was determined using an autorefractor, the intraocular pressure was measured using an iCare tonometer to determine the risk for glaucoma and the anterior and posterior segment of the eye was examined using a slit lamp, 90D lens and gonioscopy lens to determine the complications associated with aniridia. Results for each participant were recorded and participants who required further management were referred to the local Ophthalmology clinic. Data analysis was performed by the Department of Biostatistics (University of the Free State). Prevalence was calculated by dividing the number of participants with aniridia by the total number participants included in the study. Results Four participants were identified as having aniridia and thus the prevalence of aniridia was found to be 3,4% (4 out of 117). The ages of these participants were 10, 13, 17 and 20 years. Visual acuity for each eye individually ranged from no light perception to 0.86 logMAR (6/38). Corneal complications such as pannus, opacification and vascularisation were seen in all of the participants. Some form of cataract was seen in all four participants. The IOP ranged between 11mmHg and 19mmHg in 3 of the participants and was outside of the normal range (7mmHg – 21mmHg) in the 4th participant. Gonioscopy showed 75% of participants with grade 4 angles and the remaining participant with grade 2 angles. Cup-to-disc ratios varied between 0.5 and 0.8 with no glaucomatous changes. Foveal hypoplasia was present in 75% of participants and nystagmus was present in all of the participants. One participant presented with membrane-like structures in the posterior chamber of both eyes, making a view of the fundus unobtainable. Conclusion The prevalence found (3,4%) is representative of one school (Christiana School for the Blind in the North West) from the three that were included, not the whole of South Africa. Cataracts and nystagmus were the most prevalent ocular complications found in this group. The foveal hypoplasia and corneal abnormalities in conjunction with some form of cataract and nystagmus are all contributors to the reduced visual acuity observed in these participants. The findings from this study contribute to new information regarding aniridia in regions of central South Africa and enables the comparison of results with research conducted in other parts of the world. This research also provides information about the most recent prevalence of aniridia in this part of South Africa. Further research can be done in other parts of the country to support and add to these results
Les bénéfices de l’enseignement des techniques de base de perfectionnement de langue à des apprenants (faux) débutants de FLE dans un contexte non francophone
No full textThesis (Ph.D. (Afrikaans and Dutch, German and French))--University of the Free State, 2020This thesis examines the teaching of FLE with a close look at its importance in South Africa and how this subject is taught in institutions of higher education. Existing teaching methodologies in this field are analysed in the South African context to highlight the importance of a custom-made intervention for local (foreign) language teaching. In response to the preliminary analysis of this study, an innovative programme for independent vocabulary learning is proposed and tested in an action research approach with a group of second-year university faux beginners in French as a foreign language. The first objective of this study is to establish the benefits of teaching basic language improvement exercises in the FLE classroom. The programme proposed in this thesis is based on language improvement exercises for student and professional interpreters. Although these exercises have been adapted for a group of faux beginners in French as a foreign language, they can easily and with little modification be applied to any language. The results of the study summarise the participants’ reactions to the proposed intervention and show how the exercises in the programme encourage learning development in that a neo language laboratory can be designed to boost autonomous learning at different levels of language proficiency.
___________________________________________________________________Cette thèse examine l’enseignement du français langue étrangère (FLE) en s'intéressant de près à son importance en Afrique du Sud et à la manière dont cette matière est enseignée dans les établissements d'enseignement supérieur. Les méthodologies d’enseignement connues dans ce domaine sont analysées dans le contexte sud-africain afin de souligner l’importance d’une intervention sur mesure pour l’enseignement local des langues (étrangères). Pour donner suite à l’analyse préliminaire de cette étude, un programme innovant pour l'apprentissage indépendant du vocabulaire est proposé et mis à l'essai dans le cadre de la recherche actionnelle avec un groupe de faux débutants en français langue étrangère en deuxième année d'université. Le premier objectif de cette étude est d'établir les bénéfices de l'enseignement des exercices de perfectionnement linguistique de base dans la classe de FLE. Le programme proposé dans cette thèse s’inspire des exercices de perfectionnement linguistique destinés aux interprètes apprenants et professionnels. Bien que ces exercices aient été adaptés pour un public de faux débutants en français langue étrangère, ils peuvent, avec peu de modifications, s’appliquer à toute langue, qu’il s’agisse d’une langue étrangère ou non. Les résultats de l’étude résument la réaction des participants envers le programme proposé et montrent comment les exercices de ce dernier encouragent un développement de l'apprentissage indépendant dans la mesure où un néolaboratoire de langue peut se concevoir afin de stimuler l'apprentissage autonome à des niveaux différents de la maîtrise linguistique.
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Film Production Centre: exploring a layered narrative Bloemfontein, South Africa
No full textThe focus of this dissertation stems from an interest in film creation - the process from production to post production. Architects gather data from site to design on plan, elevation and section to create spaces with perspective as a tool of interpretation and envisioning. Film design uses the same rules as a site influence narrative. Film uses these same rules of perspective to envision scenes and use a frame by frame sequence to portray the visual storytelling. South Africa has established itself over the years as a place rich with environments and spaces to portray these narratives through the visual art form of film. The proposed design is film production facilities in Bloemfontein The idea is, to produce films on an international standard. The site is situated behind Naval Hill between Long Street and Rudolph Greyling Street on the piece of land that were used for transportation services. Most of these spaces have been abandoned and the existing train station on the site is being used for the project. These spaces exist in a vast natural landscape empowered by the industrial architecture in the context, creating edges and boundaries between nature and an industrial environment. The idea for this project arose from the lack of professional facilities in South Africa for production of large-scale films. The only facilities that are currently available are found in Cape Town, and these only provide services that can accommodate a few productions at a time. The idea is for the proposed facilities to make provision for the production of international standard films; to accommodate the film crews involved and to invite members of the public to visit the film sets for educational tours. The intervention aims to embrace the landscapes of Bloemfontein and to question the existing typology of film production facilities. The research conducted in this document investigates the typology of Film production facilities and educational facilities as a regeneration of space within an existing structure in a rural environment. It seeks to investigate the possibility of coming up with a new film-production process. The idea is to create a link between the film production process and the architectural design process in order to create spaces that can relate to film and the environment, and at the same time meet the requirements for film production. The dissertation will firstly identify the challenges and perimeters associated with the project through statements of aims and a research question. Thereafter, it will seek to explore and ground the concepts relating to the challenges through research, analysis, and interpreting literature. These concepts and theories will be applied as design methodologies in order to create a design and technical synthesis. Finally, the dissertation will seek to reflect on and evaluate the complete investigative process in terms of the final design synthesis and the way in which the conceptual exploration and research aided its development
A sedimentological and geochemical study of the uranium mineralization at Rietkuil Mine, Beaufort West, Karoo Basin
No full textDespite a vast amount of research conducted on the Karoo Uranium Province there is no clear definitive model for the uranium mineralization. This thesis aims to create a mineralization model for the uranium deposit at Rietkuil mine making use of detailed field mapping and geochemical analyses. This information can possibly contribute to a revised uranium mineralization model for the Karoo Uranium Province. The sediments from Rietkuil mine forms part of the Abrahamskraal Subgroup in the lower Beaufort Group (Late Permian age). It hosts uranium mineralization in horizontally bedded, very fine to fine-grained sandstone with a moderate sorting. Clay pellet conglomerate, cross-bedded sandstone, horizontally bedded sandstone, ripple cross-bedded sandstone, massive sandstone, parallel laminated siltstone and mudstone, massive mudstone, and mudstone with ball-and-pillow structures were the eight lithofacies identified at the study location. With the aid of petrographic and XRF data, the sandstone was classified as lithic-wacke and lithic-arenite. The distribution of the carbonaceous matter was strongly controlled by lithology. Fieldwork revealed that the carbon was strongly associated with horizontally bedded units. LECO analysis (total carbon), Mebius titrations (organic carbon) and field observations show that there was a decrease in the amount of carbon upwards in the lithology. Field and petrographic observations produced evidence of a Ca-rich hydrothermal fluid that intruded into the wacke. The porosity of the wacke was increased by tectonic features (joints, folds, and faults), lithological features (thin horizontally bedded layers, and interfingering sandstone lenses), mineralogical features (solution seams, absorption by a muddy matrix, and adsorption onto carbonaceous matter). These factors controlled the distribution of the uranium mineralization. The geochemical data obtained from Rietkuil mine was evaluated by using Pearson's correlation coefficients indicating elemental relationships of identified minerals. It revealed strong positive relationships between elements hosted in detrital minerals as well as elements hosted in hydrothermal minerals. The elements of the two mineral parameters though show strong negative correlations with each other. Strong positive relationships between pyrite and organic carbon were observed. Uranium showed strong positive correlations with CaO (inorganic carbon). The uranium mineralization was confined to zones with high amounts of carbon. This indicated that the carbon and pyrite produced a suitable environment for the precipitation of uranium minerals. Evidence suggests that the uranium mineralization at Rietkuil mine was a secondary uranium deposit. The uranium sourced from eroded granitic material and tuff deposits contained in underlying sedimentary rocks. XRD analysis revealed that the uranium occurred in the U+6 oxidation state thus being transported as uranyl complexes with ions like SO4-2, PO4-2, VO4-2, and AsO4-2 by a Ca-rich low-temperature hydrothermal fluid. The joints were the feeder mechanism for the transportation of fluids. When these fluids encounter the reduced environment produced by the carbon, uranium and sulfide minerals precipitated from the solution.National Research Foundation (NRF
Using transformative learning theory to prepare the assessment of work-integrated learning of university student teachers
No full textTeacher education institutions in South Africa developed assessment instruments for work-integrated learning in 2015 to meet the requirements of the initial teacher education and the policy of the minimum requirements of teacher qualifications. The aim of this study was to prepare assessment of WIL using transformative learning theory (TLT) by including the voices of student teachers. The problem in the study was that the voices of the student teachers are not included in the assessment of WIL. The study adopted TLT as the theoretical framework with participatory action research (PAR) methodology to empower and engage participants in the research study. Participants in the study were the teaching practice officer from the university, a lecturer responsible for the teaching practice module at the university, five schoolteachers who were mentors to student teachers, and ten student teachers who were at a secondary school for a WIL programme. Six meetings were held during the study to generate data following the cyclical and spiral process of PAR. The data that were generated were analysed and conceived through critical discourse analysis (CDA), which made it possible for data to be conceived at textual, discursive and social levels. The findings of the study show the need to include the voices of student teachers in the process of assessment of WIL and proposed a strategy for assessment of WIL that accommodate the students to have their voices
Investigating the impact of capacity development interventions for smallholder farmers in Ba-Phalaborwa municipality in the Mopani District, Limpopo, South Africa
No full textCapacity Development Intervention (CDI) entails transforming one‘s ability to perform a task and improve the performance of an individual in his organization or job. This study investigated the impact of Capacity Development Interventions for smallholder farmers in Ba-Phalaborwa municipality in the Mopani District of Limpopo Province in South Africa. The purpose of the study was to understand the contribution CDIs had made to the lives of the smallholder farmers, their sustainability and possibly how the implementation could be improved to optimize the impact. Mixed-method, quasi experimental design was used for the study, incorporating primary and secondary data. The data was collected through document analysis and a survey which involved administration of questionnaires to the farmers, Limpopo Department of Agriculture and Rural Development officials and training service providers. Additionally, observation techniques were used during field visits by assessing the state of production on the farms and during the interviews. The collected data was analysed using the Statistical Package for Social Scientist (SPSS). The results of the study showed that CDIs contributed positively to the farmers through open market participation, understanding production techniques, knowledge of different role players in the industry and the importance of record keeping. However, this study revealed that most of the farmers did not practice record keeping and that the evaluation methods employed in assessing the contribution of CDIs to the smallholders are not as informative. The analysis of reports from the Limpopo Department of Agriculture and Rural Development revealed that the evaluation methods currently used by the government do not assess how far the initial programme objectives have been realised; rather the focus is if the targeted numbers to be trained have been attained. Thus, based on the findings from this study it is recommended that stern measures should be taken by the relevant organizations ensuring that the agreed targets are delivered and these evaluations have to be continuously done during CDIs implementation. The outcomes from this study seek to assist in the effective implementation of CDIs and formulation of relevant CDI frameworks that will enhance the productivity of smallholder farmers across the whole of South Africa and beyond
Comparison between measured and simulated activity using Gafchromic™ film with radionuclides
No full textIn this study, Gafchromic™ film XR-QA2 and RT-QA2 were used to characterise the film energy response against various radionuclides. The film response was investigated with respect to different backscatter materials. The sensitivity of the two types of films was compared, and a film stack method was tested to allow the user to obtain sequential, cumulative doses at different time points. Monte Carlo (MC) simulations were used to link optical density (OD) values from measurements to the absorbed dose in the film. This was achieved by using conversion factors obtained by BEAMDP, BEAMnrc and DOSXYZnrc simulations to get the absorbed dose in the film. A neutron depletion theoretical model was introduced that can describe film response as a function of cumulated activity and absorbed dose. Background: Gafchromic™ film has been used for quality assurance in various studies but not in nuclear medicine applications. Once the OD has been determined after film exposure to a radionuclide, it can be linked to the absorbed dose using the air kerma rate constant at distances that approximates point sources and the dose in water can be linked to the dose in film using MC simulations to get conversion factors. MC simulations are known as a gold standard to get the absorbed dose in materials. Materials and Methods: XR-QA2 and RT-QA2 Gafchromic™ film were irradiated with the following radionuclides: Am-241, Cs-137, Tc-99m and I-131. The OD was calculated, and a function describing the relationship between the OD and the time-activity was derived based on the neutron depletion model. Different backscatter materials such as Corrugated fibreboard carton (CFC) or air equivalent material, polystyrene, Polymethyl Methacrylate (PMMA or perspex) and lead were used to investigate the effect it has on film response. The sensitivity of each film was investigated and compared. BEAMDP, BEAMnrc and DOSXYZnrc simulations were used to link the film response, OD, to the absorbed dose. The MC simulations were done replicating the exact geometry as with the physical measurements to get the absorbed dose in the film. Results: The new neutron depletion model fitted the OD vs cumulative activity accurately as well as the OD vs absorbed dose. The XR-QA2 Gafchromic™ film has shown to be the most sensitive film when using air equivalent material with radionuclides, especially with low energy radionuclides such as Am-241. When using more than one layer, the OD sensitivity of the film can be increased as well. The film stack method investigated also showed to be less time consuming when relating stacked film data to single film data. The fluence obtained from BEAMDP confirmed that the radionuclide containers have an effect on the radionuclide spectra’s. Lead was also the backscatter material which showed higher OD change but lower absorbed dose values. Conclusions: The neutron depletion theoretical model is more accurate than higher-order polynomial fits because it contains less free parameters. The XR-QA2 Gafchromic™ is better to use in nuclear medicine because of its sensitivity at low energies and because the sensitivity can be increased by using multiple layers of film. Film stack methods can be used to decrease experiment times. BEAMnrc can be used to accurately model radionuclides within their containers to evaluate the container effects. Lead showed a higher induced OD with lower absorbed dose, and the air equivalent material showed the lower OD change but higher absorbed dose
The enterprise architecture leadership styles of a South African telecommunications company
No full textDissertation (MBA (Business Administration))--University of the Free State, 2020Purpose: Enterprise Architecture is a holistic practice used in management which covers business and information technology in order to manage organisational complexities and aid strategic decision-making. Successful implementation of Enterprise Architecture is reliant on a leader who can handle the pressure that comes with the job. Although many Enterprise Architecture leaders are highly qualified and technically skilled individuals, challenges such as communication, stakeholder buy-in and governance issues are often the core hindrances to successful Enterprise Architecture. Previous research shows that Enterprise Architecture initiatives often fail due to substantial challenges demonstrated by enterprise architects' lack of authority and leadership. Due to the technical nature of Enterprise Architecture, its relationship with soft skills like leadership is often overlooked. In this, an opportunity to research the leadership styles that exist in Enterprise Architecture avails itself. The purpose of the research is to analyse the leadership styles of a telecommunications organisation in South Africa. Research design: This research design was a qualitative non-probability purposive study with semi-structured interviews. The research sample size consisted of twelve (12) participants who are actively functioning in the Enterprise Architecture domain. The sampling strategy used was a purposive sampling strategy. The research was conducted in the Telkom Group and its subsidiaries. Each participant was asked a set of demographic questions and ten (10) predefined questions in the form of semi-structured interviews. Findings: The findings showed that the most prominent leadership styles were democratic, affiliative and pacesetting leadership styles; the most common one being the affiliative style. Each leadership style was accompanied by a communication style, the most common one being assertive communication. The findings also highlighted that the participants believed that the Telkom Group had a Level 2 Enterprise Architecture maturity level and that Telkom had not fully adopted the Enterprise Architecture mindset. The participants expressed their biggest challenges as being communication, stakeholder buy-in, leadership and vision of Enterprise Architecture. Conclusion: The enterprise architects displayed strong leadership and communication styles that have a positive impact on the environment; however, due to their limited influence, they are facing challenges that require the intervention of senior leadership. The leadership styles present in the Enterprise Architecture domain are sufficient and appropriate to deal with the challenges that come with a Level 2 Enterprise Architecture maturity; however, in order to leverage the existing leadership styles, the organisation must increase the scope of influence for the enterprise architects. The use and implementation of positive leadership and communication styles will assist in dealing with the challenges and improve the Enterprise Architecture maturity level of the organisation