Do macroeconomic variables explain future stock market movements in South Africa?

This study aims to address the empirical question of whether macroeconomic variables drive future stock market returns in South Africa. If found, the macroeconomic variables would therefore constitute useful predictive information for the future FTSE/JSE All Share Index. The data was examined from 1965 to 2010 which constitutes the longest study of its nature in South Africa. The macroeconomic variables were selected based on international and local precedent of intuitive influential macroeconomic factors. Through the use of Johansen multivariate cointegration, Granger causality and innovation accounting, it was found that the selected South African macroeconomic variables did not significantly influence future FTSE/JSE All Share Index returns. Therefore the chosen macroeconomic variables should not be used as a future predictive tool for South African stock market returns

An experimental investigation into the role of autoignition in turbulent flame stabilisation

This thesis presents experimental and complimentary numerical results based on a turbulent jet in a hot coflow burner (JHC). The thesis focuses on understanding and exploring the relative importance of autoignition in the flame stabilisation process for the conditions, temperatures and fuels considered. The influence of fuel type is explored using a range of gaseous fuels including: alkanes, alkenes, H2 and dimethyl ether (DME). High-speed (10 kHz) measurements of chemiluminescence and sound are applied to all flame cases, for all fuels, the measurements are used to temporally resolve the interaction of the flame base with ignition kernels. Similar flame-base and ignition kernel interaction characteristics are found for all fuels where the formation and merging of rapidly growing ignition kernels stabilise these flames. A measurement campaign employing 10 kHz OH and CH2O Planar Laser Induced Fluorescence combined with volumetric chemiluminescence imaging is applied to the ignition kernel formation region in DME flames. The measurements identify regions of low and high-temperatures respectively, with their spatial overlap representing heat release. The kernel heat release measurements indicate that differing degrees of autoignition stabilisation occurs for DME flames, specific to high and low coflow temperature flames. High coflow temperature flames produce lower heat release ignition-kernels; hence these flames are believed to have reduced dependence on autoignition for stability. Zero-dimensional and one-dimensional numerical simulation results, obtained in this thesis, agree with the findings from the hot coflow experiments. The 0-D ignition delay times are shown to successfully capture the different fuels lift-off height sensitivities with coflow temperature. The sensitivity of relatively low coflow temperatures are particularly well represented by delay times, with a linear correlation between delay times and experimental lift-off heights. To replicate the strained and diffusive conditions induced by the JHC burner, unsteady 1-D counter-flow simulations were applied. These simulations, using DME, identify that for high coflow temperature flames, the ignition kernels produce lower heat release, since they are igniting leaner. Using CH4 with the same counter-flow setup, the effect of strain-rate was explored. It was found that increased strain rate delays ignition, since the unity balance between diffusion and production fluxes of CH2O is also delayed. Furthermore, under autoignition conditions, the counter-flow solver, in addition to a premixed solver, show CH2O convection and production fluxes increase, with a corresponding diffusive decrease

Analysing creative image search information needs.

Creative professionals in advertising, marketing, design and journalism search for images to visually represent a concept for their project. The main purpose of this paper is to present an analysis of documents known as briefs to find search facets, which are widely used in creative industries as a requirements document to describe an information need. The briefs specify the type of image required, such as the content and context of use for the image, and represent the topic from which the searcher builds an image query. This research takes three main sources - user image search behaviour, briefs, search engine meta-data - to examine the search facets for image searching in order to examine the following research question - are meta-data schemes for image search engines sufficient for user needs, or is revision needed? This research found that there are three main classes of user search facet, which include business, contextual and image related information. The key argument in the paper is that the facet 'keyword/tag' is ambiguous and does not support user needs for more generic descriptions to broaden search or specific descriptions to narrow their search - we suggest that a more detailed search facet scheme would be appropriate

'I’m just not sure': the persistence of uncertainty in the information seeking of undergraduate students with dyslexia

As information seeking progresses, it is expected feelings of uncertainty surrounding, for example, the information need, what information will be useful to satisfy the need and how well the need has been satisfied will shift towards confidence and clarity. The six corollaries offered by Kuhlthau outline and explain areas where this shift can happen. However, does it happen for all groups of information-seekers? Undergraduate students with dyslexia often have lower information seeking-related self-efficacy than their peers and this can result in uncertainty persisting throughout information seeking. Retrospective naturalistic think aloud observations were held with 20 undergraduate students with dyslexia. After looking for information for one of their (self-chosen) assignments, participants were invited to explore their thoughts, feelings and actions with the researcher while watching a screen recording of their information seeking session. First, an inductive reflexive Thematic Analysis was conducted which revealed self-efficacy to be a key influence in the information seeking behaviour of undergraduate students with dyslexia. To investigate this further, a dedicated deductive analysis was conducted leveraging Kuhlthau’s six corollaries. The expected shift away from uncertainty towards clarity and confidence was found to be either delayed, disrupted or prevented by participants’ low self-efficacy surrounding selecting and spelling keywords and reading, interpreting and evaluating information online. Uncertainty persisted throughout information seeking and was rarely reduced or resolved. Key areas for additional support during information seeking for this user group are identified, including keyword selection and spelling, accurate reading and interpretation and confident evaluation of online information.Peer Reviewe

Search strategy formulation for systematic reviews: Issues, challenges and opportunities

Systematic literature reviews play a vital role in identifying the best available evidence for health and social care research, policy, and practice. The resources required to produce systematic reviews can be significant, and a key to the success of any review is the search strategy used to identify relevant literature. However, the methods used to construct search strategies can be complex, time consuming, resource intensive and error prone. In this review, we examine the state of the art in resolving complex structured information needs, focusing primarily on the healthcare context. We analyse the literature to identify key challenges and issues and explore appropriate solutions and workarounds. From this analysis we propose a way forward to facilitate trust and to aid explainability and transparency, reproducibility and replicability through a set of key design principles for tools to support the development of search strategies in systematic literature reviews