Why Read (Diffractively)?

Academics should produce quality scholarly research. However, the demands of the marketised, neoliberal higher education institution and the increase in the academic’s bureaucratic and administrative tasks do not allow for adequate engagement with the deep work and slow forms of scholarship that are needed to produce cutting-edge and insightful research. Many academics find it challenging to think critically and creatively under such conditions, yet they are unwilling to fill their time with shallow work instead. Thus, they are torn between producing an institutionally-determined number of research outputs, and striving towards producing quality scholarly work that advances knowledge in the academic’s discipline. Reading groups serve to rework this tension by providing a communal and scheduled place and mind-space for reading major academic works. Reading takes time and persistence. We find that setting aside time and creating creative spaces for reading groups offer an opportunity for silent revolt against the pressures of the higher education institution. In this (post)qualitative inquiry we diffractively read – “through one another” – two autoethnographical accounts to experiment with our experiences of various reading groups over a period of three years while positioning ourselves in relation to Barad’s notion of diffraction. This speculative experimentation entails a myriad of ideas and methods that serve to decentre hegemonic, monolithic knowledge systems through seeking alternative ways of knowing, and recognises the importance of the entanglement of matter and meaning in tracing (and countering) the social relations produced in neoliberalist contexts. Such (re)thinking is thus a vital counterpoint to the neoliberal obsessions of the higher education context, (re)directing the scholar to new non-autonomous and mutable landscapes

Cooling capacity of vortex tubes by changing different characteristics

Published articleThe improvement of the efficiency and cooling capacity of a simple vortex tube is considered. Three Ranque-Hilsch Vortex tubes, with different diameters and lengths, were developed and manufactured. The vortex tube is an unique device with no working parts and has the ability to deliver hot and cold air simultaneously. It is a simple, low cost device, which is easy to manufacture. Different orifice sizes and nozzle configurations are designed and manufactured to investigate the performance of the three vortex tubes. The f 22 mm vortex tube with a f 7, 5 mm orifice and small diameter nozzle gave a better efficiency and an increase in the drop in temperature of the cold air against the different inlet pressures. The maximum efficiency of the f 22 mm diameter vortex tube improved from 8, 9% against a cold fraction of 0, 630 (with the f 6 mm x 2 tangential nozzle block) to 18, 92% against a cold fraction of 0, 644 (with the f 3 mm x 4 tangential nozzle block) at an inlet pressure of 500 kPa. The maximum drop in temperature of the cold air improved from 27, 0 oC against a cold fraction of 0, 120 (with the f 6 mm x 2 tangential nozzle block) to 42, 3 oC against a cold fraction of 0, 284 (with the f 4 mm x 2 tangential nozzle block) at an inlet pressure of 600 kPa

Vachellia (Acacia) karroo Communities in South Africa: An Overview

Vachellia karroo is a useful and widespread tree in Africa. It belongs to the family Fabaceae, which is the third largest woody plant family in southern Africa. This is an ecologically and economically important species as almost all of its parts, including bark, pods, seeds, leaves and thorns, are extremely useful to both humans and animals. Various commercial products are also obtained from the tree, and gum is one of the most important products. V. karroo in South Africa has an extensive distribution range that includes several biomes. It is very adaptable and has wide habitat tolerance, growing under many differing conditions of soil, climate, and altitude. Although it is often associated with heavy, clayey soils on the banks of rivers and streams, it also grows in bushveld, dry thornveld, grassland and woodland. V. karroo is easy to grow and as a result can become an aggressive invader of valuable farming land and grazing areas, a phenomenon usually referred to as bush encroachment. An analysis of historic data comprising 1553 relevés and 2006 species, compiled from all areas of South Africa where V. karroo is known to occur was conducted, and TWINSPAN classification produced five main vegetation types

ASSESSMENT OF MANUFACTURABILITY AND PERFORMANCE OF POLYURETHANE HEART VALVES PRODUCED THROUGH A LOCALLY DEVELOPED DIP MOULDING PROCESS

Conference ProceedingsPolyurethane heart valves have been widely studied as possible replacement for mechanical and bioprosthetic heart valves. The development of an inexpensive routine production technique for manufacturing of polyurethane valves will greatly benefit a very large number of patients in developing and emerging countries. A polymer heart valve shows favourable physical properties and flow dynamics compared to human heart valves, however, the outcome of producing a polymer heart valve with the required flexibility, durability and hemodynamic function is often difficult to predict. The design of the mould, the selection of the material and the fabrication method used are the key factors that influence the achievement of an acceptable heart valve for use in the human body. From their previous work on developing a repeatable, semi-automated dip moulding process for producing tri-leaflet polyurethane heart valves, the authors have shown that the selection of an appropriate set of dip moulding process parameters and mould material properties could result in achieving polyurethane valve leaflets with the required physical and mechanical properties. This paper reports on the progress made with application of the developed dip moulding process to produce polyurethane heart valves suitable for use in human body. The mould, frame and sewing ring were manufactured in Ti6Al4V(ELI) by using a Direct Metal Laser Sintering (DMLS) process and the valve leaflets were moulded directly onto the sewing ring. The heart valve properties obtained are presented and assessed. Conclusions are drawn regarding the prospects of these valves surviving the extensive in vitro simulation trials required to qualify them for subsequent clinical trials

The mature female clothing shopper : profiles and shopping behaviour

The original publication is available at http://www.sajip.co.zaCITATION: Visser, E.M., Du Preez, R. & Du Toit, J.B. 1996. The mature female clothing shopper : profiles and shopping behaviour. SA Journal of Industrial Psychology, 22(2):1-6, doi:10.4102/sajip.v22i2.603.This study was designed to profile the mature female clothing shopper. More specifically certain variables that could be attributed to differences in consumer behaviour were investigated. Mature female clothing shoppers were segmented as clothing moderates, clothing enthusiasts and the clothing unconcerned. These three cluster groups significantly differed regarding clothing involvement, clothing orientation, activities, interests, opinions, family orientation, needs and media usage. No significant differences were found among the three groups regarding evaluative criteria for clothing and clothing store attributes. Profiles of the clusters were developed, along with applicable marketing implications. Recommendations for further research are made.Hierdie studie is onderneem ten einde die vroulike kledingverbruikers van 55 en ouer te tipeer. Die veranderlikes wat 'n bydrae kon lewer ten opsigte van die verskille in verbruikersgedrag is ondersoek. Die verbruikers is gesegmenteer as die kledinggematigdes, kleding- entoesiaste en die kleding-onbetrokkenes. Die drie groeperings verskil beduidend van mekaar ten opsigte van die volgende veranderlikes naamlik: kleding-betrokkenheid, kleding-oriëntasie, aktiwiteite belangstellings, opinies, familie oriëntasie, behoeftes en media gebruik. Geen beduidende verskille kon gevind word tussen die drie groeperings ten opsigte van die veranderlikes evalueringskriteria van klere en winkeleienskappe nie. Profiele van die verskillende trosse is ontwikkel en die bemarkingsimplikasies is uitgewys. Aanbevelings vir verdere navorsing word gedoen.Publishers' Versio

Assessing a portable, real-time display handheld meter with UV-A and UV-B sensors for potential application in personal sun exposure studies

BACKGROUND : Observing accurate real-time measurements of solar ultraviolet radiation (UVR) levels is important since personal excess sun exposure is associated with skin cancers. Handheld measurement devices may be helpful but their accuracy is unknown. We compare a portable, science-grade solar UVR monitoring device against two fixed, science-grade solar UVR instruments. METHODS : Instruments were (1) a fixed Solar Light 501 UV-B biometer to measure UV-B; (2) a fixed Kipp and Zonen radiometer used to measure UV-A and UV-B; and (3) Goldilux ultraviolet probes which are commercially available portable devices. Two different probes were used, one measured UV-A and the other UV-B radiation. The Goldilux probes were levelled and secured next to the UV-B biometer. Between 10:00 and 14:40 UTC+2, the UV-B biometer was set to record at 10-minute intervals and measurements by the Goldilux probes were manually taken simultaneously. Results were compared for all data and by solar zenith angle (SZA) ranges. RESULTS : The Goldilux UV-B probe measured UV-B relatively well in its diurnal pattern, however, its readings were ~77% higher than those made by the UV-B biometer. While UV-A measurements from the Goldilux UV-A probe and those from the radiometer were in relatively good agreement in pattern, the radiometer read ~47% higher than the Goldilux UV-A probe. UV-B data from Goldilux UV-B probe had a moderately strong correlation with UV-B biometer data for small SZAs; conversely, for UV-A, the Goldilux UV-A probe had a strong correlation with the UV-A radiometer data for large SZAs. CONCLUSION : Handheld devices may be useful to provide real-time readings of solar UVR patterns, however, to achieve synchronicity in the magnitude of readings to those made by science-grade fixed instruments, devices may need to be used during certain times of the day and in clear-sky conditions which may not be practical in personal exposure studies.Dr Wright receives funding support from the South African Medical Research Council and the National Research Foundation of South Africa.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1600-08462019-11-01hj2019Geography, Geoinformatics and Meteorolog

The pharmacokinetics/pharmacodynamics of theophylline in premature neonates during the first few days after birth.

Thesis (Ph.D.)-University of Natal, Durban, 2000.Theophylline is one of the few preparations available for the treatment of apnoea of prematurity. Currently little data is available on the pharmacokinetics and the pharmacokinetic/pharmacodynamic relationships of theophylline for premature neonates during the first few days of life, a time when neonates undergo profound physiological changes and when the drug is most often used. Furthermore, the influence of theophylline on hypoxaemic episodes has not yet been quantified. The study aimed to investigate optimal theophylline dosing in this group by establishing pharmacokinetic parameters, assessing the effectiveness of the drug in abolishing apnoea and hypoxaemic episodes and investigating the concentration/effect relationship. The project was conducted in the neonatal wards of King Edward VIII Hospital, Durban, South Africa. The study group comprised a total of 105 Black, apnoeic, premature neonates, with respiratory distress syndrome, who were receiving intravenous theophylline. Serum samples (263), collected from patients during routine care, were analysed for theophylline. Forty-six patients were monitored before and after theophylline therapy with a neonatal capnograph linked to a data acquisition. Apnoea incidents were classified into total (all apnoea _20 seconds) and a hypoxaemic episode was defined as a >_10% fall for >10 seconds in peripheral oxygen saturation. Within each of these groups patients were assessed as responders (>_50% reduction in the clinical effect from baseline to the last recording) and non-responders. Patient characteristics were identified as possible markers of non-response to theophylline therapy. The Nonlinear Mixed Effects Model (NONMEM) was used to derive population pharmacokinetic models and parameters for theophylline as well as to assess the concentration-effect relationship. The pharmacokinetic analysis estimated a low clearance and volume of distribution, with oxygen support enhancing clearance. Relatively high inter-individual and residual variability values were obtained prompting testing for inter-occasion variability. This resulted in a decrease of inter-individual variability for clearance and volume of distribution as well as in residual variability. In the theophylline doses used, a significant reduction in total and pathologic apnoea but not in hypoxaemic episodes occurred over the first three days after birth. The most positive improvement was seen on the first day of treatment after the loading dose. A statistically significant increase in the average pulse rate and a decrease in episodes of bradycardia from baseline to all three days of monitoring were recorded. Most patients responded at serum theophylline concentrations of 3 to 9 mg/L. Most serum theophylline concentration measurements were also in this range and it was not possible to clearly define a concentration-effect relationship. The cumulative percentage of non-responders was relatively high for total apnoea (48%) and hypoxaemic episodes (45%), but low for pathological apnoea (13%). Being one of a set of twins was identified as a marker of poor response for both total apnoea and hypoxaemic episodes. Other possible markers for poor response, in terms of total hypoxaemic episodes, were being born by caesarean section and having more than the 75th percentile pathologic apnoea per hour at baseline. It was interesting to note that, with regard to total apnoea, there were some features that seemed to predict a favourable response to theophylline. These were birth weight and 5 minute Apgar score below the 25th percentile, and patients with baseline total apnoea counts above the 75th percentile. The cumulative graphs of the responders and non-responders resembled the fixed effect model, which is the simplest model to explain drug-effect relationships. More sophisticated analysis of the concentration-effect relationship, using NONMEM and the count model proved difficult. None of the models tested were found to be satisfactory, but that which included the influence of a hypothetical respiratory depressant factor gave the most realistic value of EC50. It is suggested that further even more complex modelling may be required to accurately define the concentration-effect relationship (and hence the therapeutic range) for theophylline in neonatal apnoea

A comparison of cyclic fatigue failure of two nickel titanium rotary endodontic file systems that use different manufacturing methods: a ground file (RaCe™) and a new innovative controlled memory file (HyFlex CM™) in a simulated root canal

Research Question - Do controlled memory nickel titanium rotary endodontic files have greater resistance to cyclic fatigue than ground nickel titanium files , in vitro, at test temperatures near those encountered clinically? Context and previous research - Controlled memory rotary files became available in 2010. Two in vitro research papers testing their resistance to cyclic fatigue against ground files have been published to date. These studies conducted their research at room temperature using a three pin bending device to rotate the files around a curvature. They both had sample sizes of twelve files per group. Controlled memory files performed significantly (p < 0.05) better than ground files. Sample and setting - Forty seven HyFlexCM™ and forty eight RaCe™ files, both with a tip size of .25mm and constant taper of 6% were randomly acquired for comparison. The HyFlexCM™ files were sponsored by the manufacturer, the RaCe™ files were purchased from a U.K supplier. Both groups were run to failure at 500 revolutions per minute in an oil lubricated artificial canal constructed from hardened steel using electrical discharge sinking. The artificial canal tapered at 6%, from .35mm to 1.37mm with a 5mm radius of curvature and 90° bend in one plane. The test temperature was 35 ± 1 °C. Data collection and Analysis - Raw data, in seconds to failure, was recorded by the author and converted to number of rotations to failure. Significance level was set at .05. Statistical analysis was performed with SPSS™ statistical software. The Cox survival model was used to determine if there was a significant difference in the number of rotations to failure for each group. Findings - There was no statistically significant difference between the two groups. Conclusion - Controlled memory rotary endodontic files may be more likely to fail through cyclic fatigue when tested at clinically relevant temperatures rather than at room temperature as in previous studies

An evaluation of language materials developed by the Language in Learning and Teaching (LILT) project in terms of the language development of the learners using them, based on what they aim to achieve and their perceived functions in the light of the guiding principles under-pinning the LILT project.

Thesis (M.A.)-University of Natal, Pietermaritzburg, 2001.The focus of the research reported on in this dissertation is an evaluation of the Language in Learning and Teaching project (LILT), in terms of its ability to facilitate English language development in schools where both educators and learners are second language speakers and where the Language of Learning and Teaching (LoLT) is English. The research involved two main phases. During the first phase I established evaluation criteria from the literature review, from another project the English Language Education Trust, (ELET) and from my own experience and feedback from the end-users (Le. teachers) and the observation of workshops. In the second phase I evaluated the LILT materials against the criteria developed in the literature review, analysed the feedback from end-users in the form of a questionnaire and made recommendations. In this dissertation the following terms will be used interchangeably: teacher, educator, facilitator and tutor because in the quoted passages, the term teacher is largely used. However, in Outcomes-Based Education (OBE) the terms educator, facilitator and tutor are used

Orthopaedic referrals using a smartphone app: Uptake, response times and outcome

Background. It is well established that South Africa (SA) suffers an immense burden of violence and injuries. The responsibility of providing care for these injuries falls mainly on public health services, resulting in overloading of the health system. Prior to a recent intervention, the large burden had been exacerbated by limitations in the traditional referral system that highlighted the need for a better referral system. Vula’s smartphone app was introduced at Tygerberg Hospital in August 2016. This study evaluated the uptake, response times and outcomes using this app.Objectives. The main objectives of the study were to describe: (i) the number of referrals; (ii) referral response times; (iii) referring facilities; and (iv) referral outcomes. Secondary objectives were to: (i) evaluate whether the referral outcome pathway was appropriate; and (ii) assess professional conduct and evidence of upskilling.Methods. This retrospective, descriptive study investigated Vula app referrals to the Division of Orthopaedic Surgery at Tygerberg Hospital between 1 August 2016 and 31 March 2017. Vula was advertised to key facilities in the hospital’s referral network. All referrals to the division during the study period were systematically included in the analysis of operational outcomes, although some were excluded from the subsequent referral outcome analysis. Operational outcomes included the number of referrals, referring facilities and referral response times. Referral outcome analysis included the clinical diagnosis, referral pathway, whether the referral was used for upskilling and whether it was conducted in a professional manner.Results. A total of 2 275 referrals from 39 different facilities were received during the study period from 238 individual users; 50% of referrals received a response within 11 minutes, while a small percentage received no response. Clinical and demographic characteristics of 1 985 patients included in the referral outcome analysis indicated that the majority of trauma and emergency referrals involved males, with closed fractures being the most frequent clinical presentation. Although the most common referral outcome was immediate transfer, one-third of the patients were treated at the referring hospital with advice only.Conclusions. The large volume of orthopaedic referrals received through the Vula app suggests that Vula represents a successful alternative to traditional referral methods. Referrals managed by advice only could suggest that Vula facilitates some relief for the overburdened trauma services. Future research could further explore Vula’s role in strengthening the public health system, including interventions for high-volume referral areas and upskilling of referring health workers.