An Examination of the Interaction Between Modelling and Its Relationship with Construction Kits: Lessons from the Past and for the Future

Construction kits have played a significant part in nurturing the growth and development of the minds and manipulation-based skills of children (and adults) in formal and non-formal education settings. These kits have origins rooted in the representation of the built world and now have a diversity of form and function, including technical versions with moving parts. This article examines some of the historically based ideas that lie behind the role that kits may have in terms of physical modelling. The article traces the transformation of kits from simple bricks and blocks into more complicated pieces for space-filling and achieving the transfer of forces and motion. This transformation occurred during the Victorian era when the influence of the ideas of educationalists and, perhaps rather strangely, exponents of early aviation, played major roles in determining the diversity of forms of construction kit and modelled possibilities that are now to be seen in classrooms and homes. The article ends with a review of some of the lessons from the past and present that will need to be considered in relation to concrete modelling in schools for the future. This revised version was published online in July 2006 with corrections to the Cover Date.     

Evidence on agglomeration economies,diseconomies, and growth

Conventional urban economic analysis suggests that a local economy's size is closely related to a number of features, including levels of human capital and the availability of specialized inputs, which are likely to influence positively the rate at which it accumulates further economic activity. At the same time, urban theory also suggests that once cities reach a certain level of size, these agglomeration benefits begin to peter out, while diseconomies rise rapidly. Consequently, we should see an ‘inverted U‐shaped’ pattern of growth with respect to economic size—rates of growth first rise, then fall as size increases. This paper shows that, while such a pattern is largely absent from recent data on growth in metropolitan area population and employment, it emerges strikingly in county‐level data. Copyright © 2002 John Wiley & Sons, Ltd.     

The Impact of the Implementation of Technology Education on In-Service Teacher Education in South Africa (Impact of Technology Education in the RSA)

In this article the impact of technology education, as a new learning area (subject) in the curriculum, on in-service teacher education in South Africa is described in order to ascertain the extent of the impact. The research on which this article is based draws on a variety of experiences and observations in the field at grassroots level (in particular an outreach project in rural communities). The envisaged impact of technology education on South African schools, communities, teacher educators and teachers, the range of in-service teacher education that is required, and the impacts in urban and rural areas are discussed. Finally a number of concluding remarks are made about the extent of the impact of the inclusion of technology education in the new National Curriculum Statement and whether the situation has changed since the implementation of a pilot technology education project in 1998. This revised version was published online in July 2006 with corrections to the Cover Date.     

DURATION MOMENTS AND YIELD CURVE MOVEMENTS

In this paper we will analyze the relationship between the value and duration moments of a cash flow and movements in the yield curve. We will show that for changes in the yield curve which can be related to tⁿ , the 1st order changes in the net present value of a cash flow are linearly dependent on the n + lth duration moments, and that the 2nd order changes are dependent on the sum of duration moments of order 2 n + 1 and 2 n + 2. We will use this relationship to tilt tracking portfolios so as to protect them against specific changes in the yield curve.     

Relative Significance of Journals,Authors, and Articles Cited in Financial Research

We evaluate journals based on their relative contributions to top-level finance research in a recent period. Journals are ranked according to the number of citations found in articles published in Journal of Finance, Journal of Financial Economics, Journal of Financial and Quantitative Analysis, and Review of Financial Studies. The analysis controls for both the average number of articles and average number of words published annually in each cited journal. We identify the fifty most frequently cited journals during this period. We also list the fifty most frequently cited authors and articles and note topical trends in the research.     

Significant Issues for the Future of Product Innovation

The value of a technology strategy has been increasingly discussed by R&D personnel and those involved in product development and business planning efforts. In this issue Albert Rubenstein and Americo Albala elevate this discussion by showing the importance of preparing a firm to compete by stressing the development of important, relevant technologies. Discovery and development must be channeled into areas that will be needed to support business initiatives likely to occur in the future. Albala stresses the importance of this change for the development of economies in nations that have been disappointed by the lack of success of importing technologies from more developed nations, while Rubenstein maintains that the pace of marketplace change requires a technology strategy in order to reduce the misapplication of scarce resources within the firm and the possibility of being blindsided by competitive developments. These essays continue a year-long series of contributions that the editor-in-chief solicited from members of the editorial board. Members were asked to reflect upon changes and opportunities that they see influencing our profession during the coming decade. Both of these short essays are designed to introduce new perspectives. It is not essential that you agree with the recommendations, but we hope that you are stimulated as you reflect on the issues they raise.