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1.
Eric F. Parkinson 《International Journal of Technology and Design Education》2004,14(3):219-243
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. 相似文献
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This paper first examines the rapid growth and changing composition of manufactured exports in Indonesia and Thailand, highlighting the rapid growth of office and computer machinery and electric machinery, somewhat slower growth of non-electric and transportation machinery, as well as the low growth of previously large exports of textiles apparel. Second, the important contributions of foreign multinational enterprises (MNEs) to export growth in the machinery industries, particularly in electric, office, and computing machinery, are documented. Third, the paper describes trade policies in all these industries in some detail, emphasizing how low protection was a key facilitator of rapid export growth in the MNEs that dominated the electric, office, and computing machinery industry, while high protection reduced incentives to export among MNEs in the transportation machinery industry. 相似文献
4.
In July 2006, the European Union's (EU) Common Market Organization (CMO) for sugar underwent the first radical reform since its establishment in 1968. In this article, we study the incentives for adoption of new technologies before and after the policy reform. We build a stochastic partial equilibrium model and use it to analyze the effect of the policy reform on the adoption incentives of genetically modified herbicide tolerant sugar beet. Our findings show that the adoption incentives of high‐cost sugar beet farmers are significantly reduced under the new CMO. Medium‐cost producers, in contrast, have greater incentives to adopt new technologies, while low‐cost producers are largely left unaffected. The reduced adoption incentives of high‐cost farmers lead to lower flexibility and competitiveness of these farmers and therefore coincides with the goals of the reform to crowd out high‐cost producers and increase competitiveness of the European sugar market. En juillet 2006, l'Organisation commune du marché (OCM) du sucre a subi sa première réforme radicale depuis sa mise en place par l'UE en 1968. Dans la présente étude, nous avons examiné les incitatifs offerts pour l'adoption de nouvelles technologies, avant et après la réforme. Nous avons élaboré un modèle stochastique d'équilibre partiel et l'avons utilisé pour analyser les répercussions de la réforme sur les incitatifs offerts pour l'adoption de variétés de betteraves sucrières génétiquement modifiées résistantes aux herbicides. Selon nos résultats, les incitatifs offerts aux producteurs de betterave sucrière ayant des coûts marginaux élevés ont significativement diminué depuis la réforme de l'OCM du sucre. Par contre, les incitatifs offerts aux producteurs ayant des coûts marginaux moyens se sont accrus, tandis que ceux offerts aux producteurs ayant de faibles coûts marginaux n'ont pas changé. La diminution des incitatifs offerts aux producteurs ayant des coûts marginaux élevés entraîne une diminution de la souplesse et de la capacité concurrentielle de ces producteurs et, par conséquent, coïncide avec les objectifs de la réforme qui visent àévincer les producteurs ayant des coûts marginaux élevés et à accroître la capacité concurrentielle du marché européen du sucre. 相似文献
5.
Because the break-up of conglomerates typically produces substantial increases in shareholder wealth, many commentators have argued that the conglomerate form of organization is inefficient. This article reports the findings of a number of recent academic studies, including the authors' own, that examine the causes and consequences of corporate diversification. Although theoretical arguments suggest that corporate diversification can have benefits as well as costs, several studies have documented that diversified firms trade at a significant discount from their single-segment peers. Estimates of this discount range from 10–15% of firm value, and are larger for “unrelated” diversification than for “related” diversification. If corporate diversification has generally been a value-reducing managerial strategy, why do firms remain diversified? One possibility, which the authors label the “agency cost” hypothesis, is that top executives without substantial equity stakes may have incentives to maintain a diversification strategy even if doing so reduces shareholder wealth. But, as top managers' ownership stakes increase, they bear a greater fraction of the costs associated with value-reducing policies and are therefore less likely to take actions that reduce shareholder wealth. Also, to the extent that outside blockholders monitor managerial behavior, the agency cost hypothesis predicts that diversification will be less prevalent in firms with large outside blockholders. Consistent with this argument, the authors find that companies in which managers own a significant fraction of the firm's shares, and in which blockholders own a large fraction of shares, are significantly less likely to be diversified. If agency problems lead managers to maintain value-reducing diversification strategies, what is it that leads some of these same firms to refocus? The agency cost hypothesis predicts that managers will reduce diversification only if pressured to do so by internal or external mechanisms that reduce agency problems. Consistent with this argument, the authors find that decreases in diversification appear to be precipitated by market disciplinary forces such as block purchases, acquisition attempts, and management turnover. 相似文献
6.
Backtesting Value-at-Risk: A Duration-Based Approach 总被引:2,自引:0,他引:2
Financial risk model evaluation or backtesting is a key partof the internal model's approach to market risk management aslaid out by the Basle Committee on Banking Supervision. However,existing backtesting methods have relatively low power in realisticsmall sample settings. Our contribution is the exploration ofnew tools for backtesting based on the duration of days betweenthe violations of the Value-at-Risk. Our Monte Carlo resultsshow that in realistic situations, the new duration-based testshave considerably better power properties than the previouslysuggested tests. 相似文献
7.
The Internet has successfully generated an ever-expanding cohort of users for all its major concomitant activities, including information gathering, communications and transactions. So far no attempt has been made to validate whether such a success is so deep as to transcend national cultures. Nor any work has been conducted to compare the internationalisation1 performances between online usage activities. The current study addresses these two research gaps from the perspective of four countries, i.e. Britain, Germany, Japan and Taiwan. Results show that although the technological forces have been quite successful in internationalising overall online usage activities, they succumb to the cultural forces as far as only the transactions activity, or more colloquially online purchase, is concerned. This indicates the relative difficulty in internationalising online purchase vis-à-vis other online usage activities. Further research on locating a series of step functions or kick-off time points regarding the development of online purchase is suggested. 相似文献
8.
Eric Dor Bruno Van der Linden Maritza Lopez-Novella 《Oxford bulletin of economics and statistics》1997,59(1):109-131
This paper is interested in the modelling of the relationship between active and passive labour market policies and the aggregate unemployment outflow rate. Our model is based on a matching function and includes a simple representation of the competition between various groups of job searchers. The empirical analysis uses Belgian data. Faced with variables that are often integrated of order 1 according to the usual tests but which cannot strictly speaking be integrated, we contribute to an important methodological debate by comparing the conclusions of a classical econometric analysis and a cointegration approach. 相似文献
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How does the presence of multinational companies affect plant survival in the host country? We postulate that multinational companies can impact positively on plant survival through technology spillovers. We examine the nature of the effect of multinationals using a Cox proportional hazard model, which we estimate using plant‐level data for Irish manufacturing industries. Our results show that the presence of multinationals has a life‐enhancing effect only on indigenous plants in high‐tech industries, suggesting the presence of technology spillovers. In contrast, multinationals compete with each other in low‐tech sectors in the host country. 相似文献