void nag_mv_prin_coord_analysis(Nag_Eigenvalues roots, Integer n, double d[], Integer ndim, double x[], Integer tdx,

g03fa

The role of tutors in the effectiveness of cooperative learning physics tutorials

Includes bibliographical references (leaves 104-108).Group problem solving tutorials have been in lise in the Department of Physics at the University of Cape Town for more than a decade. They are implemented with the belief that students have the opportunity to develop problem-solving skills through interacting with each other, and are able to make sense of physics concepts through conversation and reasoning with their peers. These problem solving sessions are supervised by tutors who are typically postgraduate students. The present project focused on understanding the role that these tutors play in facilitating learning in cooperative problem solving physics tutorials, and explored the factors that result in a group of students deciding to call a tutor, the different ways in which tutors interact with a group of students, and the factors which are related to the intervention of tutors that affect the learning outcomes in a physics cooperative learning session

Reactivity to Confidence Ratings During Reasoning and Problem Solving

Confidence ratings are one of the most frequently used measures of metacognition. Is has traditionally been assumed that confidence ratings can be elicited from individuals without affecting their underlying cognitive and metacognitive processes. Recently, research has challenged this assumption by demonstrating changes in cognitive performance in reaction to providing self-report measures of metacognition, so-called reactivity. The purpose of this thesis was to extend these findings by examining reactivity to confidence ratings in reasoning and problem-solving tasks. After introducing theory relevant to metacognition and reactivity in Chapter 1, Chapter 2 provides a meta-analysis of reactivity to judgements of learning. This meta-analysis indicated that positive reactivity (a facilitation of cognitive performance) occurs in response to related, but not unrelated word-pairs. Chapter 3 presents one of the first empirical studies of reactivity to confidence ratings, demonstrating that confidence ratings benefit performance on an IQ test, but reactivity is moderated by trait-like self-confidence. In Chapter 4 the effect of eliciting confidence ratings on metacognitive monitoring and control is examined. The results show that collecting confidence ratings impairs metacognitive monitoring. Additionally, metacognitive control is affected, in that confidence ratings prompt participants to focus on short-term performance, rather than long-term performance. Chapter 5 shows that the word ‘confident’ may prime pre-existing beliefs about one’s competence, which results in reactivity effects. Finally, Chapter 6 evaluates reactivity to prospective confidence ratings. The results indicate that eliciting prospective confidence ratings facilitates performance on a cognitive task. Implications for the measurements of metacognition and the use of confidence ratings in research, as well as the potential use of confidence ratings as an educational intervention are discussed in Chapter 7

Child and adult mortality in Zimbabwe, 1980-2005

This research applies direct and indirect methods to data from censuses and Demographic and Health Surveys to derive empirical estimates of the level and trends of child and adult mortality in Zimbabwe from 1980 to 2005

Integer iobj, Integer ncolh,

e04nkc nag opt sparse convex qp (e04nkc

Microstructural Characterization of Graphite Spheroids in Ductile Iron

The present work brings new insights by transmission electron microscopy allowing disregarding or supporting some of the models proposed for spheroidal growth of graphite in cast irons. Nodules consist of sectors made of graphite plates elongated along a hai direction and stack on each other with their c axis aligned with the radial direction. These plates are the elementary units for spheroidal growth and a calculation supports the idea that new units continuously nucleate at the ledge between sectors

The design, evaluation and costing of biomass gasifiers

The objective of this study has been to enable a greater understanding of the biomass gasification process through the development and use of process and economic models. A new theoretical equilibrium model of gasification is described using the operating condition called the adiabatic carbon boundary. This represents an ideal gasifier working at the point where the carbon in the feedstock is completely gasified. The model can be used as a `target' against which the results of real gasifiers can be compared, but it does not simulate the results of real gasifiers. A second model has been developed which uses a stagewise approach in order to model fluid bed gasification, and its results have indicated that pyrolysis and the reactions of pyrolysis products play an important part in fluid bed gasifiers. Both models have been used in sensitivity analyses: the biomass moisture content and gasifying agent composition were found to have the largest effects on performance, whilst pressure and heat loss had lesser effects. Correlations have been produced to estimate the total installed capital cost of gasification systems and have been used in an economic model of gasification. This has been used in a sensitivity analysis to determine the factors which most affect the profitability of gasification. The most important influences on gasifier profitability have been found to be feedstock cost, product selling price and throughput. Given the economic conditions of late 1985, refuse gasification for the production of producer gas was found to be viable at throughputs of about 2.5 tonnes/h dry basis and above, in the metropolitan counties of the United Kingdom. At this throughput and above, the largest element of product gas cost is the feedstock cost, the cost element which is most variable