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Anne R. Fitzpatrick Valerie B. Link Wendy M. Yen George R. Burket Kyoko Ito Robert C. Sykes 《Journal of Educational Measurement》1996,33(3):291-314
In one study, parameters were estimated for constructed-response (CR) items in 8 tests from 4 operational testing programs using the l-parameter and 2- parameter partial credit (IPPC and 2PPC) models. Where multiple-choice (MC) items were present, these models were combined with the 1-parameter and 3-parameter logistic (IPL and 3PL) models, respectively. We found that item fit was better when the 2PPC model was used alone or with the 3PL model. Also, the slopes of the CR and MC items were found to differ substantially. In a second study, item parameter estimates produced using the IPL-IPPC and 3PL-2PPC model combinations were evaluated for fit to simulated data generated using true parameters known to fit one model combination or ttle other. The results suggested that the more flexible 3PL-2PPC model combination would produce better item fit than the IPL-1PPC combination. 相似文献
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The dynamics of R&D network in the IT industry 总被引：1，自引：0，他引：1
In this paper, we provide an empirical analysis of evolving networks of successful R&D collaborations in the IT industry (consisting of firms that obtained patents in the technological category of computers and communication) in the U.S. between 1985 and 1995. We first show that the R&D network has become more extensive, more clustered, and more unequal in the sense that ‘stars’ have emerged in the network. We then analyze the effect of the existing network structure in the process of new R&D collaboration formation. We control for unobserved similarities among firms based on the community structures within the network that the algorithm developed by Girvan and Newman (2004) identifies and find a significant cyclic closure and preferential-attachment effect. 相似文献
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Ryo Yoshii 《International Journal of Inclusive Education》2016,20(8):844-854
In the late nineteenth and early twentieth centuries, American psychologists began addressing problems related to the intellectual capacity of students enrolled in public schools. This paper focuses on the role and influence of psychologists in addressing these problems, specifically the difficulty of classifying students deemed feeble-minded and backward. This paper discusses the diagnostic theory of the clinical psychologist John Edward Wallace Wallin (1876–1969), who was one of America's leading proponents of diagnosing and classifying students in public schools. I show that, in addressing treatment for the feeble-minded and backward, he emphasised educational instruction suited to a child's individual needs and adopted individual/multiphase methods rather than primarily focusing on efficiency-based diagnostic methods. In a democratic society, such as the USA, it was important to establish educational placement and differentiated instruction suited to individual needs. 相似文献
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Reading and Mathematics tests of multiple-choice items for grades Kindergarten through 9 were vertically scaled using the three-parameter logistic model and two different scaling procedures: concurrent and separate by grade groups. Item parameters were estimated using Markov chain Monte Carlo methodology while fixing the grade 4 population abilities to have a standard normal distribution. For the separate grade-groups scaling, grade groupings were linked using the Stocking and Lord test characteristic curve procedure. Abilities were estimated using the maximum-likelihood method. In either content area, scatterplots of item difficulty, discrimination, and ability estimates from the two methods showed consistently strong linear relationships. However, as grade deviated from the base grade of four, the best-fit linear line through the pairs of item discriminations started to rotate away from the identity line. This indicated the discrimination estimates from the separate grade-groups procedure for extreme grades to be, on average, higher than those from the concurrent analysis. The study also observed some systematic change in score variability across grades. In general, the two vertical scaling approaches yielded similar results at more grades in Reading than in Mathematics. 相似文献
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Complexation of π-conjugated ligands by metal or semimetal ions leads to the enhancement of the planarity and rigidity of π-conjugated systems. Boron, especially, has played a central role in the design of luminescent main-group complexes. However, these complexes still suffer the disadvantage of aggregation-caused quenching as well as typical organic fluorophores. It has recently been reported that some types of boron complexes exhibit the aggregation-induced emission (AIE) property. Moreover, AIE behavior from complexes and organometallic compounds composed of the other group 13 elements, such as aluminum and gallium, has emerged in this decade. These observations greatly encourage us to develop advanced functional materials based on the group 13 elements. Indeed, recent research has demonstrated that these classes of materials are potentially versatile scaffolds for constructing chromic luminophores, efficiently emissive π-conjugated polymers and so on. This review mainly describes AIE-active group 13 complexes with four-coordinate structures and their application as photo-functional materials. Proposed mechanisms of the origins of AIE behavior are briefly discussed. 相似文献
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Kyle R. Lynch Han C. G. Kemper Bruna Turi-Lynch Ricardo R. Agostinete Igor H. Ito Rafael Luiz-De-Marco 《Journal of sports sciences》2017,35(24):2421-2426
The objective of the present study was to investigate the effects of different sports on stress fractures among adolescents during a 9-month follow-up period. The sample was composed of 184 adolescents divided into three groups (impact sports [n = 102]; swimming [n = 35]; non-sports [n = 47]). The occurrence of stress fracture was reported by participants and coaches. As potential confounders we considered age, sex, resistance training, body composition variables and age at peak of height velocity. There were 13 adolescents who reported fractures during the 9-month period. Bone mineral density values were higher in adolescents engaged in impact sports (P-value = 0.002). Independently of confounders, the risk of stress fracture was lower in adolescents engaged in impact sports than in non-active adolescents (hazard ratio [HR] = 0.23 [95% confidence interval (CI) = 0.05 to 0.98]), while swimming practice was not associated to lower risk of fracture (HR = 0.49 [95% CI = 0.09 to 2.55]). In conclusion, the findings from this study indicate the importance of sports participation among adolescents in the reduction of stress fracture risk, especially with impact sports. More importantly, these results could be relevant for recognising adolescents in danger of not reaching their potential for peak bone mass and later an increased risk of fractures. 相似文献
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Ryo Ito Naoyuki Yamashita Eiko Suzuki Takaaki Matsumoto 《Journal of sports sciences》2015,33(9):892-898
Outdoor exercise often proceeds in rainy conditions. However, the cooling effects of rain on human physiological responses have not been systematically studied in hot conditions. The present study determined physiological and metabolic responses using a climatic chamber that can precisely simulate hot, rainy conditions. Eleven healthy men ran on a treadmill at an intensity of 70% VO2max for 30 min in the climatic chamber at an ambient temperature of 33°C in the presence (RAIN) or absence (CON) of 30 mm · h?1 of precipitation and a headwind equal to the running velocity of 3.15 ± 0.19 m · s?1. Oesophageal temperature, mean skin temperature, heart rate, rating of perceived exertion, blood parameters, volume of expired air and sweat loss were measured. Oesophageal and mean skin temperatures were significantly lower from 5 to 30 min, and heart rate was significantly lower from 20 to 30 min in RAIN than in CON (P < 0.05 for all). Plasma lactate and epinephrine concentrations (30 min) and sweat loss were significantly lower (P < 0.05) in RAIN compared with CON. Rain appears to influence physiological and metabolic responses to exercise in heat such that heat-induced strain might be reduced. 相似文献
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Banri Ito 《Research Policy》2007,36(8):1275-1287
The large expansion of MNC's overseas R&D is noteworthy. This paper investigates the factors affecting the expansion of support-oriented R&D and knowledge sourcing R&D by using qualitative data which indicate the modes of R&D conducted at a plant site and a laboratory. The empirical results suggest that (1) the export propensity of affiliate firms, relative abundance of human resources for R&D, and accumulated technological knowledge have a positive effect on both the modes of R&D at a plant site and a laboratory, and (2) the stronger enforcement of intellectual property positively affects the expansion of knowledge sourcing R&D. These results show that not only firm-specific but also country-specific factors positively affect the overseas expansion of R&D. 相似文献