OpenUCT is the open access institutional repository of the University of Cape Town (UCT). It preserves and makes UCT scholarly outputs digitally and freely available, including theses and dissertations, journal articles, book chapters, technical and research reports, as well as open educational resources.
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Within breath changes in airways calibre measured by the continuous measurement of respiratory impedance to forced oscillations
(1987) Davidson, Robert Nicolas; Sivarasu, Sudesh
The author bench-tested a commercially available instrument for measuring respiratory impedance (Siregnost FD5: Siemens); resistance (R) and phase changes were accurately recorded in models. In a subject given an inhalation of histamine, respiratory resistance (R) was closely comparable to Rrs measured by the Mead-Whittenberger technique.
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Open Access
Modelling the impact of SuDS for stormwater quality management in the Bongani River catchment, Knysna
(2023) Van der Merwe, Calvin David; Armitage, Neil Philip
The Bongani River is a primary pollutant source of stormwater runoff discharging into a shallow portion of the Knysna Estuary known as the Ashmead Channel (Harvey, 2019), situated on the southern coast of South Africa along the Garden Route. The Ashmead Channel is experiencing continuous macroalgal blooms which threaten the ecosystem's biodiversity (Human et al., 2016; Claasens et al., 2020). Furthermore, the recurring algal blooms have impacted – and will continue to impact – the aesthetic appearance and intrinsic value of the ecosystem goods and services provided by this environment (Allanson, 2010). The Herald Reporter (2019) highlighted that SANParks and the public are concerned about pollution and have expressed their desire to improve the quality of stormwater runoff entering the Knysna Estuary. One of the ways to improve the quality of stormwater in the Bongani River is to introduce Sustainable Drainage Systems (SuDS) into the catchment area to aid in improving stormwater management. SuDS aim to achieve holistic management of water quantity and flooding, water quality and surface water pollution, public amenity and community inclusion, and the conservation and protection of biodiversity (Armitage et al., 2013; Woods Ballard et al., 2015). The feasibility of reducing nutrient loads using SuDS was investigated by developing a hydrological model of the Bongani River. The base model, alongside several intervention scenarios, was developed in PCSWMM (Personal Computer Stormwater Management Model). Flow data collected during the study were used to calibrate the base model. Additionally, water quality was integrated into the models using event mean concentration (EMC) wash-off parameters for Total Nitrogen (TN) and Total Phosphorus (TP), which were estimated from an analysis of grab samples. The calibrated model was designated as the Current Scenario and was compared to the following additional scenarios: • Pre-development Scenario – the Current Scenario modified to represent, as closely as reasonably possible, the likely state of the site before human development. • Settlement Upgrade Scenario – incorporating the potential upgrading of the low-income areas to that more akin to typical suburban conditions. • Tributary Management Scenario – incorporating a detention wetland on the western tributary and a retention wetland on the eastern tributary of the Bongani River to manage pollution from the low-income settlements. • Bongani Wetland Upgrade Scenario – incorporating a constructed wetland near the discharge point as a regional control for the entire catchment. The evaluation of the five scenarios was undertaken in two ways: Calvin David van der Merwe MSc. Civil Engineering • In terms of flow quantity which was based on the reduction of flow volume and maximum flow rate in a 20-year timeseries. The Bongani Wetland Upgrade Scenario performed best with reductions of total volume by 77% and maximum flow rate by 71%, with the Settlement Upgrade Scenario and Tributary Management Scenario following, respectively. • In terms of water quality which was based on the theoretical reduction of TN and TP loads over five consecutive 2-year periods. The Bongani Wetland Upgrade Scenario also performed best with reductions of 78% for TN and 77-78% for TP, followed by the Settlement Upgrade Scenario with reductions of TN by 66-75% and TP by 70-74% and the Tributary Management Scenario with reductions of 47-51% for TN and 47-52% for TP. All three of the scenarios achieved the pollutant reduction objectives described in the literature. However, the solutions would need to be combined to achieve the pollutant levels seen in the Pre-development Scenario, which compared with the Current Scenario, was 89% lower for TN and 90% lower for TP.
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Open Access
My sun printed archive is blue
(2023) Van der Merwe, Petronella; Steyn, Morné; Matchett, Sarah
I'm a white Afrikaner. I am spun from a villainous history - a vestige signifying coloniality. I have inherited a colonial archive that documents my ancestor's journey as a Rhenish missionary from Germany to Namibia in the year 1863. From a contemporary present that is framed by post-colonial and postcolonial discourse, colonial archives warrant verwerking/ alteration/ processing/ working and reworking. Framed by practice-led research, this study uncovers how I can verwerk my colonial archive through performance to incite transgression of preservation, to move beyond the ossification of colonial heirlooms (my archive) to reconcile with emerging post-colonial futures. In my performance, I transform my colonial archive into tactile textile - linen. Linen, in its entirety as ‘text embedded tapestries' symbolises narratives, history and the past, all woven together to form what constitutes the present. The word ‘lineage' originates from the noun ‘line'. The word ‘line' in turn, etymologically stems from the term lino meaning linen - the flax seed fabric (Miller 2005: 239). A single thread can therefore signify themes of genealogy, heritage, identity and ancestry (van der Merwe 2022: 2). I am interested in modes of reworking and reimagining my colonial archive. I perform acts such as tainting, tearing, ripping, (re)stitching and untangling large tapestries of linen - embodying a scrutiny of my white colonial archive. In my performance research I demonstrate a ‘grappling with' my colonial past from my contended post-colonial present. I ‘taint', ‘scratch' and make marks - as I attempt to insert new perspectives and self-reflective insight. Incited by my performance research, I uncovered the notion of poisoning and the image of a moth as two potent concepts in relation to the notion of verwerking . In relation to the linen, a moth has the capacity to devour, consume and process material (established as a metaphor for my archival text). The moth is me, devouring and processing my colonial text. Secondly, I taint the white, bleached linen using cyano-type printing that results in mournful, sickly blue stains and blotches smeared across the once white tapestries - signifying alteration and transgression of preservation. It can be stated that I poison my colonial text. From the poison emerges remedy and an attempt to reconcile with the past. I unpack the notion of poison alongside Jacques Derrida's (1998) concept of pharmakon (poison as remedy). These alterations and indiscretions to my colonial archive and it's text offer emergence, allowing my ossified colonial archive to evolve beyond a preserved state. For me, my explication and performance research can ultimately become a new chapter in my family's archive that reflects on a past that is interwoven and entangled up within villainous history - that warrants acknowledgement and critical reflection.
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Open Access
Marathon running: the physiological and pathological effects with particular reference to renal function and fluid shifts
(1990) Irving, Robert Anthony; Tim, Noakes
Marathon running can induce acute renal failure and hyponatraemia and may be associa~ed with the formation o f renal stones. The pathogenesis o f these conditions is uncertain and the physiological =esponse with regard to renal function and fluid shifts 2as not been clearly defined, particularly during the r ecovery days after mara thon running. In t his thesis, eight marathon races were studied and da i ly blood and 24 hour urine samples ~ere collected. The fo llowing were measured or calc~: ated: urine output, creatinine, osmolal, free water =nd renal beta2- microglobulin clearances as well as total protein, sodiu::i., potassium, urea and creatinine e xcretion rates. Changes in total serum contents of sodium, =h loride, albumin, total protein and uric acid, and in p l ~sma volume and mean cell volume, were calculated. Plasma c -reactive protein concentrations, aspartate transc.::i nase, lactate dehydrogenase and creatine kinase activities were also measured. VI Urine samples from runners who participated in a further 2 marathons were subjected to parti cle counting, while deposited crystals were examinec #ith a scanning electron mircroscope and X-ray powder diffraction. Eight runners who developed hyponatraemia after an 88km marathon were studied during recovery, for fluid and sodium balance and renal function. The principal finding was that contrary to traditional belief, renal function as measured by urine output, creatinine, osmolal and free-water clearance, urea and creatinine excretion and production is generally well maintained. Plasma volume was maintained during a 56km marathon due to intravascular protein and sodium influxes, while a decreased urine sodium excretion occurred for at least 24 hours after the race. Urine beta2-microglobulin excretion and plasma beta2- microglobulin concentration increased but renal tubular impairment was not generally found. During the post-race days there was an increase in creatinine clearance as well as a plasma volume expansion (of up to 12.5%) due to an intravascular influx of albumin (17g on Day 1) and an increased plasma content of sodium. Two of the total of 27 runners studied developed temporary renal tubular dysfunction; one was clearly related to an inadequate fluid intake. VII The crystalluria found in runners was identical to that of. recurrent stone formers. Crystalline particles were mainly calcium oxalate dihydrate with crystal aggregation and numerous crystals in the 15-40 um diameter range. Thus runners are at risk of stone formation. VIII Finally, it was shown that the hyponatraemia of exercise was caused by fluid overload (between 1.2 and 5.9L), with only moderate sodium loss. The subjects' plasma volumes were markedly decreased (up to 24%). During the recovery period both creatinine clearance and urine output were elevated.
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Open Access
Legacies and afterlives of Dutch colonialism: told and imagined accounts of South African colonial histories in contemporary exhibition practice
(2024) Valley, Greer; Makhubu, Nomusa; Schramm, Katharina
This research takes a critical stance to what is commonly referred to as the ‘decolonial turn' in European museums, exemplified by the recent prevalence of ‘decolonial exhibitions' and programming to be found across the continent. Specifically, it analyses current representations of Dutch colonialism in the Netherlands and South Africa through the case study exhibition: Goede Hoop: South Africa and the Netherlands from 1600, which was on display at the Rijksmuseum in Amsterdam from February 17 to May 21, 2017. Through a close reading of this case, this study examines how questions of national identity, racialised self–and–other ideologies, and notions of epistemic violence and cognitive injustice relate to the materialities of museum display and exhibition practices. By investigating the colonial epistemologies and practices that continue to haunt contemporary European museum exhibitions in the wake of global imperialism, the study evaluates whether exhibitions might serve as interventionist instruments to demolish colonial systems inside museum institutions and build strategies to unlearn imperial knowledge. By analysing the contemporary cultural phenomenon of the ‘decolonial exhibition', the study demonstrates how the practices and approaches adopted in these projects can contradict their stated objectives and fail to address the core challenges and legacies of colonialism. Positioned as benevolent gestures, postcolonial museum exhibitions in the Netherlands and elsewhere in Europe frequently elicit contentious public debates but do little to address the repatriation and restitution of stolen heritage from former colonies and the ongoing, urgent issue of reparations for colonial violence. They instead foster or strengthen colonial assumptions of cultural and racial superiority.