1834 research outputs found
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A phenomenological study of problematic internet use with massively multiplayer online games
No full textMassively multiplayer online games (MMOG’s) are a specific form of online computer games that allow for millions of people to simultaneously play online at any time. This form of online gaming has become a huge phenomenon worldwide both as a popular past time and a business endeavour for many individuals. There are more than 16 million people worldwide who subscribe to fantasy role-playing online games. Although such games can provide entertainment for many people, they can also lead to problematic Internet use (PIU). PIU has also been referred to as Internet addiction, and can cause significant problems in an individual’s functioning. The study aimed to enhance a greater understanding of the phenomenon of male adults’ experiences PIU with MMOG’s. More specifically the study aims to identify if PIU with MMOG’s can be considered a form of Internet addiction within South Africa. Furthermore, assisting in the further development of online addiction diagnosis and treatment strategies. The study utilised an interpretive phenomenological approach (IPA) and participants were purposively sampled. The data was collected using semi-structured individual interviews. Furthermore, Braun and Clarks thematic analysis was used during data analysis while incorporating the four major processes in phenomenological research, namely 1) epoche, 2) phenomenological reduction, 3) imaginative variation and, 4) synthesis. Themes that emerged from the analysis of the participants’ experiences included, initial description of use, motives for continued use of MMOG’s, consequences of PIU with MMOG’s, perceptions of PIU with MMOG’s, and treatment considerations. This study provided a thick description of South African and international literature and combines the literature with the themes that emerged from the participants experiences in order to produce discussions based on the findings of this qualitative study. Conclusions, recommendations, and limitations of this study informed future research on cyber citizenship by providing a detailed understanding of the context of South African male adults’ experiences of PIU with MMOG’s.National Research Foundation (South Africa
Nest-site selection, nesting behaviour and spatial ecology of female Nile crocodiles (Crocodylus niloticus) in South Africa
No full textNesting biology and ecology have been investigated for Nile crocodiles (Crocodylus niloticus), but information on behaviour and movement patterns of nesting females during nest guarding is scant. Consequently, we investigated the home ranges, nest-site selection strategies, movement patterns, activity levels and nest fidelity of four nesting females using telemetry. Gravid females selected winter basking/breeding areas close (351 ± 2 m) to nest-sites. Mean home range and core-use areas of nesting females were 8539 ± 4752 m2, and 4949 ± 3302 m2 respectively. Mean home range (0.85 ha) was significantly smaller than those of non-nesting females (108.4 ha) during nesting season. Activity levels and mean daily movements while nesting were 8.1 ± 2.5% and 213 ± 64 m, respectively, and increased to 47.9 ± 11.7% and 2176 ± 708 m post-nesting. Overall levels of nest fidelity were 82.8 ± 11.7%, (day 78.1 ± 15.9%; night 87.3 ± 7.8%). Highest nest fidelity recorded during incubation was 99.7% over 96 days. Telemetry data from nesting females were helpful for elucidating spatial and behavioural patterns during the nest guarding period, and provided novel insights into this biologically important eventNational Research Foundation (South Africa
TGA-FTIR characterization of bamboo wood, Napier grass, pine wood and peach pips for gasification applications
No full textThe pyrolysis characteristics of four biomass materials (bamboo, Napier grass, pine and peach pips) were studied in an inert atmosphere using a simultaneous TGA-FTIR instrument. The behavior of these materials under non-isothermal conditions and at three different heating rates (20, 100 and 200 ° C / min) were compared. The gasses released during TGA analysis were analyzed using inline FTIR. Higher heating rates were found to increase conversion and had lower activation energies. Napier grass has the lowest conversion which could be due to the amount of silicon contained in most grasses. A distinguishable hemicellulose decomposition peak was detected on the DTG curve of the peach pips. Pine wood has the highest conversion (~ 88%) of the four biomass materials. The average conversion achieved for the other materials was approximately 75%. The kinetic parameters of each material computed using a model fitting method are reported. The dehydration stage in general shows lower activation energies than the active and passive pyrolysis stages.National Research Foundation (South Africa
Avian thermoregulation in the heat: evaporative cooling in five Australian passerines reveals within-order biogeographic variation in heat tolerance
No full textEvaporative heat loss pathways vary among avian orders, but the extent to which evaporative cooling capacity and heat tolerance vary within orders remains unclear. We quantified the upper limits to thermoregulation under extremely hot conditions in five Australian passerines: yellow-plumed honeyeater (Lichenostomus ornatus; ∼17 g), spiny-cheeked honeyeater (Acanthagenys rufogularis; ∼42 g), chestnut-crowned babbler (Pomatostomus ruficeps; ∼52 g), grey butcherbird (Cracticus torquatus; ∼86 g) and apostlebird (Struthidea cinerea; ∼118 g). At air temperatures (Ta) exceeding body temperature (Tb), all five species showed increases in Tb to maximum values around 44–45°C, accompanied by rapid increases in resting metabolic rate above clearly defined upper critical limits of thermo neutrality and increases in evaporative water loss (EWL) to levels equivalent to 670–860% of baseline rates at thermo neutral Ta. Maximum cooling capacity, quantified as the fraction of metabolic heat production dissipated evaporatively, ranged from 1.20 to 2.17, consistent with the known range for passerines, and well below the corresponding ranges for columbids and caprimulgids. Heat tolerance limit (HTL, the maximum Ta tolerated) scaled positively with body mass, varying from 46°C in yellow-plumed honeyeaters to 52°C in a single apostle bird, but was lower than that of three southern African ploceid passerines investigated previously. We argue this difference is functionally linked to a smaller scope for increases in EWL above baseline levels. Our data reiterate the reliance of passerines in general on respiratory evaporative heat loss via panting, but also reveal substantial within-order variation in heat tolerance and evaporative cooling capacity.NRF-South Afric
The occurrence of Shiga-toxin producing Escherichia coli in South African game species
No full textNational Research Foundatio
Investigation of coenzyme A levels in plasmodium falciparum to ascertain the mode of action of new antimalarial candidates
No full textNational Research Foundatio
Syphilis, skin, and subjectivity: historical clinical photographs in the Saint surgical pathology collection
No full textThis study concerns an archive of disused historical clinical photographs within the Saint Surgical
Pathology Collection (SSC) that originally served as teaching aids for the benefit of student doctors
at the University of Cape Town's (UCT) medical school. Focusing on images of patients diagnosed
with syphilis produced between 1920 and 1961, this study represents the first critical visual enquiry
of these images and, as such, has directly contributed to their current life within a (publically
accessible) learning collection at UCT's Pathology Learning Centre (PLC).
Set against a backdrop of psycho-social notions of health and disease, this study engages the visual
coding of syphilis in relation to Cape Town's medical history, and the developing conventions of
photography within this scientific field. Through close readings of selected images, a critical focus
on extra-clinical details, inconsistencies, and emotive qualities within the photographic frame allows
a consideration of how these photographs take part in a continuous meaning-making process that
troubles any easy, fixed, or disinterested reading.
By focusing on concepts of sublimation and projection, I unpack the photographic depiction of
ruptured skin in the SSC as an attempt to render the syphilitic patient-body a passive object of
medical knowledge. To achieve this the work of Hal Foster, Erin O'Connor, and Jill Bennett form
the theoretical foundation to address the affective potential of imaging disease necessarily limited
in efforts to secure the diagnostic function of this clinical material. However, while these
photographs emerge in this discussion as decisively structured and composed, I likewise address
how the 'Syphilis' images offer a way of seeing beyond their institutional use.
While acknowledging the disciplinary motivations of the Foucauldian medical gaze, my argument
ultimately privileges the subjects of these images while critically considering how the conspicuous
nature of this disease may have seen it pose a particular threat to a notion of stable subjecthood.
This was especially the case in the context of 20th century South Africa where those most vulnerable
to the disease were in many respects second-class citizens.
Ultimately, this investigation seeks to (re)address the SSC in an attempt to unpack how these
photographs may speak beyond their historical medical purpose. By examining how photographic
representations of patients provide a means of seeing beyond their institutional intent, I suggest
ways in which these images offer up points of fracture that offset and even resist a medical gaze and
instead provide an opportunity for the human subject to be retrieved from the objectifying tendencies
of medicine.National Research Foundatio
Application of solar pasteurization for the treatment of harvested rainwater
No full textNational Research Foundatio
Wideband direction finding of RFI for MeerKAT
No full textThe Karoo desert in the Northern Cape of South Africa is currently host to the
MeerKAT radio telescope – a precursor facility for the Square Kilometre Array
(SKA) project. The area was selected due to its natural quietness from man-made
sources of radio-frequency interference (RFI), as the telescope site needs to uphold
demanding electromagnetic compatibility (EMC) standards in order to perform
sensitive radio astronomy observations. It is therefore necessary that the facility
monitors the spectrum across MeerKAT’s operational bandwidth to identify the
presence of noise sources that may compromise the integrity of future measurements.
This thesis presents the design and simulation of a direction finding (DF)
solution that will prove to be an essential means of locating and mitigating on-site
or outside sources of interference. The asymptotic conical dipole (ACD) antenna
is implemented with a 3D-printed plastic design, coated in metal to achieve an
impedance bandwidth greater than 100:1. Four units of these designs are manufactured
for use in a multi-receiver system, which applies a phase correlation DF
algorithm to estimate the bearing of an impulse source. The accuracy of arbitrary
antenna configurations is investigated by simulation to evaluate the performance
under noisy conditions. Field measurements are conducted that verify the simulated
angular resolution of the system, which obtains source angle estimates within
±2.5
◦ accuracyNational Research Foundatio
Deubiquitination: does the answer to cardiotoxicity lie within the ubiquitin proteasome pathway
No full textCardiotoxicity, a complication that arises from anthracycline use is one
that has confounded scientists for decades. Attempts have been made to attenuate
the development of this condition through the use of anti-oxidants with little success
and this has led to calls for new adjuvant therapies. One area that has been
identified as a potential intervention involves the ubiquitin proteasome system (UPS)
and its regulation and degradation of proteins that control mitochondrial morphology,
apoptosis and cellular anti-oxidants. This process can be reversed through the use
of de-ubiquitinating enzymes (DUBs); however their role in this context is relatively
unknown. Therefore, this study aimed to investigate the role of specific DUBs
relevant in this context and whether the manipulation of their protein expression
levels will be beneficial.National Research Foundatio