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Open Access
A comparison of three class separability measures
(2004) Mthembu, N S; Greene, J R
Measures of class separability can provide valuable insights into data, and suggest promising classification algorithms and approaches in data mining. We compare three simple class separability measures used in supervised machine learning. Their relative effectiveness is evaluated through their functional relationships and their random projections of data onto R 2 for visualization. We conclude that the simple direct class separability measure of a dataset is an easier and more informative measure for separability than the class scatter matrices approach and it correlates well with Thornton’s Separability’s index.
Open Access
A seeded ambient temperature ferrit process for the treatment of AMD waters: Magnetite formation in the presence and absence of calcium ions under steady state operation
(2003) Morgan, B E; Lahav, O; Hearne, G; Loewenthal, R E
An ambient temperature ferrite process has been developed for the removal of iron and non-ferrous metals from AMD waters. The process involves the controlled formation of magnetite (Fe3 O4 ) that has the capacity to substitute divalent and trivalent cations as part of the lattice, thus forming a stable easy-to-separate ferrite. This paper reports on continuous operations of the process in the absence and presence of Ca2+, which is well known to impede ferrite formation. In the first instance, the process involves the precipitation of hydroxy-metals at pH 10.5 and their subsequent adsorption onto magnetite seed in a contact stabilisation reactor. Second, liquid-solid separation is effected and the solid fraction is subsequently treated in an oxidising reactor in which a fraction of the ferrous species is oxidised to an intermediate ferric precipitate. Finally, both ferrous and ferric species undergo crystalchemical processing and are incorporated into stable magnetite. Results indicate that Ca2+ interference can be overcome by maintaining a high ratio of precipitated ferrous species to dissolved Ca2+. It was found that in order to attain the required high Fe2+:Ca2+ ratio, the solid ferrous-hydroxy species concentration in the oxidation reactor should be maintained at above 1 200 mg Fe/l. Ferrous to calcium ratios greater than 3 were found to favour magnetite formation. In the absence of Ca2+, a solid ferroushydroxy species concentration of approximately 500 mg/l was sufficient for magnetite formation. Operating the process at ferroushydroxy concentrations of lower than 1 200 and 500 mg/l in the presence and absence of calcium respectively enhanced the formation of other iron oxides, primarily goethite. In all experiments the iron concentration in the effluent was less than 1 mg/l, the sludge volume index (SVI) extremely low (< 4 ml/g) and the percentage of ferrous-hydroxy species in the sludge can be reduced to about 1%. These features, together with the potential to incorporate heavy metals into a stable compound, make the process very promising for AMD treatment.
Open Access
A Sensitivity Analysis of Model Structure in Stochastic Differential Equation and Agent-Based Epidemiological Models
(2014) Combrink, James
The dynamics of infectious diseases have been modelled by several universally recognised procedures. The most common two modelling methods are differential equation models (DEM) and agent based models (ABM). These models have both been used through the late 20th and early 21st century to gain an understanding of prevalence levels and behaviour of infectious diseases; and subsequently to forecast potential impacts of a treatment. In the case of a life-threatening disease such as Malaria, it is problematic to be working with incorrect predictions and an epidemic may result from a misinformed judgement on the required treatment program. DEM and ABM have been documented to provide juxtapositioned results (and conclusions) in several cases, even whilst fitting identical data sets [Figueredo, et al. 2014]. Under the correct model, one would expect a fair representation of an infectious disease and hence an insightful conclusion. It is hence detrimental for the choice of treatment tactics to be dependent on the choice of model structure. This honours thesis has identified the necessity for caution on the model methodology and performs a sensitivity analysis on the incidence and prevalence of an infectious disease under varying levels of treatment. This thesis hones in on modelling methodology under various structures: the procedure is applicable to any infectious disease, and this thesis provides a case study on Malaria modelling with a later extension into Ebola. Beginning with a simple Susceptible-Infected-Recovered-Susceptible (SIRS) model: immediately obvious differences are examined to give an indication of the point at which the models lose integrity in direct comparability. The SIRS models are built up to include varying levels of exposure, treatment and movement dynamics and examining the nature of the differences in conclusions drawn from separate models.
Open Access
A simple method for visualizing labelled and unlabelled data in high-dimensional spaces
(2004) Greene, J R
The low-dimensional visualisation of highdimensional data is a valuable way of detecting structure (such as clusters, and the presence of outliers) in the data, and avoiding some of the pitfalls of blind data manipulation. Projection based on principal component analysis is widely employed and often useful, but it is a variancepreserving projection which takes no account of class labels, and may, for this reason, hide significant structure. Here we present a very simple method which appears to yield useful visualizations for many datasets. It is based on a random search for a linear transformation, and projection into a twodimensional visual space, which maximises an objective measure of class separability in the visual space. The method, which can be thought of as a variant of projection pursuit with a novel interest measure, is demonstrated on datasets from the UCI Repository. Tentative interim results are also given for a proposed extension based on spectral clustering, for extending the method to unlabelled data.
Open Access
Addressing the impact of HIV/AIDS on children in South Africa - Priorities for funders and development agencies
(Children's Institute, 2004-03) Meintjes, Helen; Giese, Sonja
This briefing paper is structured into two parts. Part A provides a brief overview of orphan numbers and what we know about the living circumstances of children growing up in the context of HIV/AIDS in South Africa. Part B of the paper provides a set of key recommendations to guide funders in responding to the impact of HIV/AIDS on children.
Open Access
African penguins Spheniscus demersus recolonise a formerly abandoned nesting locality in Namibia
(2003) Roux, J-P; Kemper, J; Bartlett, P A; Dyer, B M; Dundee, B L
African Penguins Spheniscus demersus disappeared from Neglectus Islet probably between 1885 and 1952. Visiting birds were only noted rarely before the mid 1990s, but since 1995 penguin numbers on the islet have increased and breeding was first confirmed in 2001. Neglectus Islet is the only formerly abandoned nesting locality to be recolonised by African Penguins in Namibia. Although the population is still very small (estimated at around 11 breeding pairs), the re-establishment of this breeding locality is important for the conservation of the African Penguin, which is considered to be Critically Endangered in Namibia.
Open Access
An empirical evaluation of evolutionary controller design methods for collective gathering task
(2015) Jang, Jae
This research aims to evaluate the performance of evolutionary controller design methods for developing a collective behaviour for a team of robots. The methods tested in this research are NEAT which is capable of finding minimal solution quickly, and SANE which maintains high genetic diversity through neuron level evolution. The task chosen for these methods was a collective gathering task which required a team of robots to cooperate in finding and retrieving item of interest. Our results showed that NEAT consistently produced better controllers compared to SANE.
Open Access
Analysis of the 2008/09 budget of the Gauteng provincial Department of Social Development: is the budget adequate for implementing the Children's Act?
(Children's Institute, 2008-04) Budlender, Debbie; Proudlock, Paula
Open Access
Analysis of the 2008/09 budget of the Western Cape provincial Department of Social Development: Is the budget adequate to implement the Children's Act?
(Children's Institute, 2008-04) Budlender, Debbie; Proudlock, Paula
Presented by Paula Proudlock to the Western Cape Provincial Legislature, 18 April 2008.
Open Access
Analysis of the 2008/2009 budgets of the nine provincial departments of social development: are the budgets adequate to implement the Children's Act?
(Children's Institute, 2008-07) Budlender, Debbie; Proudlock, Paula
Open Access
Approaches from the literature: Activity Theory, new tools and changing educators' practices
(2016-02-03) Glover, Michael; Czerniewicz, Laura; Walji, Sukaina; Deacon, Andrew; Small, Janet
For a study being undertaken to investigate if and how educator practices change through MOOC development and engagement with open education, Activity Theory provides a heuristic to observe contradictions and changing educator practices after the addition of new tools to a learning environment. Ours is a longitudinal study with cross case analysis of lead educators in 3-4 MOOCs, examining themes and contradictions emerging from the semi-structured data analysis to observe change in practices. In this poster we explore the question: how and why has activity theory been used to examine the introduction of new tools/mediating artefacts into the learning environment. A fuller version of our literature review is available at http://bit.ly/1jwyit3; our study’s design amalgamates the three approaches below. Our study is conducted by Laura Czerniewicz and the MOOC team at the Centre for Innovation in Learning and Teaching
Restricted
ARHAP Tools Workshop Report
(2004-06) Cochrane, James R; Schmid, Barbara
The African Religious Health Assets Programme (ARHAP) was proposed in April 2002 and initiated in December of that same year, under the joint leadership of three individuals: Dr Gary Gunderson and Prof Deborah McFarland, both of Emory University (Department of International Health), and Prof James Cochrane of the University of Cape Town (Department of Religious Studies). It is the front edge of a global religious health assets initiative. It was predicated upon a conviction that faith-based organizations, groups and movements, though playing a significant role in the delivery and promotion of health, are generally not well understood or sufficiently visible to public health systems in most societies. The underlying assumption, of course, is that we need a much more “intelligent science” about the role and importance of religious health assets (RHAs) than is currently available (or if available, then only in scattered and fragmented form). This assumption stems from the growing awareness in public health bodies of all kinds, from multilateral bodies such as the UN or the WHO and international NGOs to local governments, that faith-based health activities are a very important part of the effective meeting of ideals such as those embodied in the Millennium Development Goals and their equivalents at less global levels.
Open Access
Assessing an exit strategy for prostituted women
(2011-11) UCT Knowledge Co-op
This is a psychological study that looked at the exiting strategies of prostituted women using an interpretative phenomenological approach. It aimed to provide feedback for Embrace Dignity, a Cape Town-based NGO, on how effective their model was in providing an exit from sex work for prostituted women.
Open Access
Attempting to limit the attribution of capital gains
(2005) West, C; Roeleveld, J
Paragraphs 68 to 72 of the Eighth Schedule to the Income Tax Act No. 58 of 1962 (‘the Act’) were inserted to perform the same function as that of section 7, namely to attribute income in cases in which the taxpayer has disposed of that source of income by means of donation, settlement or other disposition. Paragraph 73 of the Eighth Schedule to the Act was inserted to limit the total amount that is attributed to the donor in a year in which both income (in terms of section 7) and a capital gain (in terms of the attribution paragraphs 68 to 72) are to be attributed. The unclear construction of the section and, it is submitted, the inaccurate interpretation of this paragraph by the South African Revenue Services (‘SARS’) has made it difficult to interpret this paragraph. This article attempts to evaluate prevailing legal precedent and to apply such precedent to the paragraphs on attribution in order to arrive at an appropriate interpretation of paragraph 73. The approach adopted by SARS is also examined in the light of the above interpretation and application of prevailing legal precedent. Lastly, amendments to the legislation are proposed to clarify the legislation and to provide a structured approach in the consideration of the intention of the legislature.
Open Access
Barriers to justice : deaf people and the courts
(2001) Morgan, Ruth
Open Access
Basic Human Rights Documents for South Africans
(1998) Amien, Waheeda; Farlam, Paul
Restricted
Benefits and requirements of interworking between wirelessLAN and 3G wireless
(2004) Chan, H Anthony
The IEEE 802.11 family of WirelessLAN enable broadband wireless access at low cost but has limited distance range. The 3G Wireless network enable wireless data access over much longer distance of cellular sites and with the handover and roaming can be used globally. Yet the 3G Wireless may be more expensive. The WirelessLAN and 3G Wireless have different capabilities in distance range, data rate, and in other features, and may complement each other. Combining WLAN and 3G Wireless data through interworking will enable these LAN and WAN technologies to complement each other to enhance the available wireless network services. These benefits are of value to both users and service providers. The requirements of interworking and the technological implications of these requirements are discussed here.
Open Access
Beyond the Brother: Radical Freedom
(2008) Barnard-Naude, A J
In his decision in Ferreira v Levin NO, Justice Ackermann - inspired by Berlin - appears to favour the negative conception of freedom. Yet at the same time Ackermann insists that 'a broad and generous interpretation of freedom does not deny or preclude the constitutionally valid, and indeed essential, role of state intervention in the economic as well as the civil and political spheres.'
Open Access
Bridging the Span Towards Justice: Laurie Ackermann and the Ongoing Architectonic of Dignity Jurisprudence
(2008) Cornell, Drucilla
Justice Laurie Ackermann has played a pivotal role in the development of the dignity jurisprudence of South Africa. At the heart of Ackermann's journey is nothing less than bravery exhibited by a constant struggle with the development of a dignity jurisprudence worthy of a constitution that does not simply forsake its moral grounding in ideals and values but insists that enumerated rights must always be defended alongside the aspiration to live up to those ideals and values.
Open Access
The case of OpenUCT: Increasing access to UCT's research and teaching outputs
(2013-07) Goodier, Sarah; Czerniewicz, Laura
This is a print version of our ePoster presented at the 5th African Conference for Digital Scholarship & Curation, held in Durban from 26 to 28 July 2013. The print version presents a slightly more detailed look at our online presence work with 16 UCT academics.