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This paper investigates the determinants of R&D investment at the national level with an emphasis on the roles of patent rights protection, international technology transfer through trade and FDI, and economic growth, in addition to the essentials of human capital accumulation and the number of scientific researchers. The Extreme-Bounds-Analysis (EBA) approach is applied to examine the robustness and sensitivity of these factors.The results of the EBA tests on data from 26 OECD countries from 1996 to 2006 showed that tertiary education and the proportion of scientific researchers in a country were robust determinants that had positive effects on R&D intensity. Foreign technology inflows had a robust and negative impact on domestic R&D. Patent rights protection and the income growth rate are fragile determinants of R&D investment.  相似文献   
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Describing the plastic deformation of aluminium softball bats   总被引:1,自引:1,他引:0  
Hollow aluminium bats were introduced over 30 years ago to provide improved durability over wooden bats. Since their introduction, however, interest in hollow bats has focused almost exclusively around their hitting performance. The aim of this study was to take advantage of the progress that has been made in predicting bat performance using finite elements and apply it to describe bat durability. Accordingly, the plastic deformation from a ball impact of a single-wall aluminum bat was numerically modelled. The bat deformation from the finite-element analysis was then compared with experiment using a high-speed bat test machine. The ball was modelled as an isotropic, homogeneous, viscoelastic sphere. The viscoelastic parameters of the ball model were found from instrumented, high-speed, rigid-wall ball impacts. The rigid-wall ball impacts were modelled numerically and showed good agreement with the experimentally obtained response. The strain response of the combined bat-ball model was verified with a strain-gauged bat at intermediate ball impact speeds in the elastic range. The strain response of the bat-ball model exhibited positive correlation with the experimental measurements. High-speed bat-ball impacts were performed experimentally and simulated numerically at increasing impact speeds which induced correspondingly increased dent sizes in the bat. The plastic deformation from the numerical model found good agreement with experiment provided the aluminium work hardening and strain rate effects were appropriately described. The inclusion of strain rate effects was shown to have a significant effect on the bat deformations produced in the finite-element simulations. They also helped explain the existence of high bat stresses found in many performance models.  相似文献   
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Background: Demonstration is a widely used method in sports teaching and coaching, based on the assumption that it is more beneficial than verbal instructions or trial-and-error methods for skill acquisition. Although in teaching/coaching situations, the demonstration is usually carried out in front of the learners, in a research context, it is most often presented via a video. However, a direct comparison between these two types of model has rarely been undertaken in a motor context.

Purpose: In this study, we aimed to compare the effectiveness of the observation of a live and a videomodel for the early acquisition of a complex judo movement.

Research Design: Participants observed either a live or a videomodel executing the task. After observation, they practised for three minutes taking five trials and then performed it for analysis. This procedure was repeated three times. The form and technique of each participant's execution were evaluated using a technical score.

Main results: The results indicated a significant improvement in the task execution by the end of the practice session. However, this improvement occurred only for the video-model group between the second and third blocks of practice.

Conclusions: The video demonstration seems more effective than the live one for the early acquisition of a completely new complex coordination. This may be due to the simplification of the visual information in the former condition because of its two-dimensionality. This simplification may allow the observer to identify the more key elements that would guide him/her for the subsequent performance of the task.  相似文献   
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The sociopolitical context of Norway includes low poverty rates and universal access to subsidized and regulated Early Childhood Education and Care (ECEC). In this context, the association between family income dynamics and changes in early child behavior problems was investigated, as well as whether high‐quality ECEC buffers children from the effects of income dynamics. In a population‐based sample (N = 75,296), within‐family changes in income‐to‐needs predicted changes in externalizing and internalizing problems (from ages 18 to 36 months), particularly for lower income children. For internalizing problems, ECEC buffered the effect of income‐to‐needs changes. These findings lend further support to the potential benefits of ECEC for children from lower income families.  相似文献   
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