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1.
The present study investigates the degree to which item "bias" techniques can lead to interpretable results when groups are defined in terms of specified differences in the cognitive processes involved in students' problem-solving strategies. A large group of junior high school students who took a test on subtraction of fractions was divided into two subgroups judged by the rule-space model to be using different problem-solving strategies. It was confirmed by use of Mantel-Haenszel (MH) statistics that these subgroups showed different performances on items with different underlying cognitive tasks. We note that, in our case, we are far from faulting items that show differential item functioning (D1F) between two groups defined in terms of different solution strategies. Indeed, they are "desirable" items, as explained in the discussion section  相似文献   
2.
Adverse effects of energy restriction on myogenic enzymes in judoists   总被引:1,自引:1,他引:0  
In this study, we examined the effects of weight reduction by restricting energy intake on muscle function and serum concentrations of myogenic enzymes in judoists. Twenty-seven male judoists aged 19.3 +/- 0.6 years (mean +/- s) were divided into three groups based on the extent of body weight reduction: high weight reduction (height 1.70 +/- 0.05 m, body mass 78.5 +/- 13.6 kg), low weight reduction (height 1.70 +/- 0.05 m, body mass 80.7 +/- 13.1 kg) and a group that maintained body weight while continuing to perform exercise training (height 1.78 +/- 0.07 m, body mass 78.7 +/- 8.8 kg). Body composition, blood biochemistry, energy intake and anaerobic power were assessed on four occasions: 20 days (baseline data), 4 days and 1 day before and 7 days after competition. Compared with baseline, body mass and fat-free mass were significantly lower 1 day before competition in the high and low weight reduction groups (both P < 0.01); these changes persisted for 7 days after competition in the high weight reduction group. Serum creatine kinase was significantly elevated 1 day before competition in all groups (all P < 0.05), and remained higher 7 days after competition in both the high and low weight reduction groups. Compared with baseline, maximal anaerobic power was significantly lower 1 day before competition only in the high weight reduction group (P < 0.01). Our results suggest that energy restriction in addition to intense exercise training before major competition has an adverse effect on anaerobic power and elevates serum creatine kinase concentration, leading to an impairment of muscular function and an increased susceptibility of muscle tissue to injury.  相似文献   
3.
ABSTRACT

Although computational approaches to ideology-based audience fragmentation are promising, they are not without limitations. First, most existing studies have focused on the US, and the cross-national validity of their results has rarely been tested. Second, previous studies that rely solely on behavioral data from social media tend to make strong analytical assumptions such as that Twitter users prefer to follow media and politicians whose ideological positions are similar to their own, and that the ideologies of political elites can be extrapolated to infer the ideologies of ordinary users. We aim to address these limitations. First, we focus on Japan to test the generalizability of US findings in an Asian context. Second, we do not rely solely on behavioral measurement but combine survey and social media data to infer the ideologies of Twitter users. Results indicate that our classifier built based on these self-reported ideologies produces more valid estimates than naïve extrapolation from views of the elites. Based on these improved estimates of Twitter users’ ideologies, we demonstrate that the ideological distributions of those who follow major Japanese media accounts on Twitter largely overlap, suggesting an absence of ideology-based audience fragmentation.  相似文献   
4.
Rugby has given Fiji international recognition and reputation. Not only is rugby a source of national pride but it has also become a valuable export, with an estimated 500 Fijian players currently in foreign leagues in, for instance, New Zealand, Australia, France, England and Japan. The economic and sociocultural gains from rugby migration are often considerable, and consequently, many players in Fiji aspire to secure foreign club contracts as their personal and professional goal. However, little is known about the realities and challenges of the players' lives after their active playing career, the burden of which falls largely upon informal, community-/family-based support networks. Such informal structures are increasingly under strain especially in urban areas and, faced with a lack of formal structural support mechanisms, many retired athletes experience a number of socio-economic and emotional problems. Some negotiate their post-rugby life successfully, while many struggle with becoming and being an ‘ex’. Based on semi-structured interviews, the present paper explores these athletes' experiences of ‘life after rugby’ and illuminates the local and international neoliberal power dynamics that intersects Fiji rugby.  相似文献   
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The international perceptions of Japanese young adults were explored in 172 professional education students in two Tokyo colleges. They classified 30 nations according to their “current” and “future” affinity to Japan. Little difference was detected in the Q-sorts between institutions arid sexes, while the “current” and “future” sorts correlated .96 with each other. In cluster analyses, many two-nation units (e.g., Czechoslovakia-Yugoslavia) were found to be the building blocks for the overall pattern. The total configuration consisted of three broad groups: mostly Western European nations, problematical nations (China, Russia, Israel, Egypt, etc.), and remote and neutral nations. Structurally, the results were similar to those for American young adults, but the contents were different. The notion of cultural metastereotypes thus received tentative support.  相似文献   
7.
In a social system or production line,the restrictions of the cost and the due-time exist in each period.Generally,whether these restrictions are satisfied is dependent not only on the risks of this period,but also on the risks generated beforehand.We consider controlling the production process by switching the processing rate to a faster one at a given period.This paper deals with the optimal switching period to minimize the total expected cost of the production process.We first propose the optimal switching period model,and then the mathematic formulation of the total expectation is presented.Finally,the policy of optimal switching period is investigated in detail by numerical experiments.  相似文献   
8.
We investigated combined effects of ambient temperature (23°C or 13°C) and fraction of inspired oxygen (21%O2 or 13%O2) on energy cost of walking (Cw: J·kg?1·km?1) and economical speed (ES). Eighteen healthy young adults (11 males, seven females) walked at seven speeds from 0.67 to 1.67 m s?1 (four min per stage). Environmental conditions were set; thermoneutral (N: 23°C) with normoxia (N: 21%O2) = NN; 23°C (N) with hypoxia (H: 13%O2) = NH; cool (C: 13°C) with 21%O2 (N) = CN, and 13°C (C) with 13%O2 (H) = CH. Muscle deoxygenation (HHb) and tissue O2 saturation (StO2) were measured at tibialis anterior. We found a significantly slower ES in NH (1.289 ± 0.091 m s?1) and CH (1.275 ± 0.099 m s?1) than in NN (1.334 ± 0.112 m s?1) and CN (1.332 ± 0.104 m s?1). Changes in HHb and StO2 were related to the ES. These results suggested that the combined effects (exposure to hypoxia and cool) is nearly equal to exposure to hypoxia and cool individually. Specifically, acute moderate hypoxia slowed the ES by approx. 4%, but acute cool environment did not affect the ES. Further, HHb and StO2 may partly account for an individual ES.  相似文献   
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10.
ABSTRACT

Based on concerns about the item response theory (IRT) linking approach used in the Programme for International Student Assessment (PISA) until 2012 as well as the desire to include new, more complex, interactive items with the introduction of computer-based assessments, alternative IRT linking methods were implemented in the 2015 PISA round. The new linking method represents a concurrent calibration using all available data, enabling us to find item parameters that maximize fit across all groups and allowing us to investigate measurement invariance across groups. Apart from the Rasch model that historically has been used in PISA operational analyses, we compared our method against more general IRT models that can incorporate item-by-country interactions. The results suggest that our proposed method holds promise not only to provide a strong linkage across countries and cycles but also to serve as a tool for investigating measurement invariance.  相似文献   
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