Two new methods to estimate the asymptotic covariance matrix for marginal maximum likelihood estimation of cognitive diagnosis models (CDMs), the inverse of the observed information matrix and the sandwich-type estimator, are introduced. Unlike several previous covariance matrix estimators, the new methods take into account both the item and structural parameters. The relationships between the observed information matrix, the empirical cross-product information matrix, the sandwich-type covariance matrix and the two approaches proposed by de la Torre (2009, J. Educ. Behav. Stat., 34, 115) are discussed. Simulation results show that, for a correctly specified CDM and Q-matrix or with a slightly misspecified probability model, the observed information matrix and the sandwich-type covariance matrix exhibit good performance with respect to providing consistent standard errors of item parameter estimates. However, with substantial model misspecification only the sandwich-type covariance matrix exhibits robust performance. 相似文献
Hemispheric predominance has been well documented in the visual perception of alphabetic words. However, the hemispheric processing of lexical information in Chinese character recognition and its relationship to reading performance are far from clear. In the divided visual field paradigm, participants were required to judge the orthography, phonology, or semantics of Chinese characters, which were presented randomly in the left or right visual field. The results showed a right visual field/left hemispheric superiority in the phonological judgment task, but no hemispheric advantage in the orthographic or semantic task was found. In addition, reaction times in the right visual field for phonological and semantic tasks were significantly correlated with the reading test score. These results suggest that both hemispheres involved in the orthographic and semantic processing of Chinese characters, and that the left lateralized phonological processing is important for Chinese fluent reading. 相似文献
This study examined the effects of in utero exposure to maternal depression and Superstorm Sandy, a hurricane that hit metropolitan New York in 2012, on infant temperament at 6 months. Temperament was assessed using the Infant Behavior Questionnaire-Revised. Maternal depression was measured by the Edinburgh Postnatal Depression Scale. The main effects and the interaction of maternal depression and Sandy exposure on infant temperament were examined using a multivariable generalized linear model. Results show that prenatal maternal depression was associated with lower emotion regulation and greater distress. Stratification and interaction analyses suggested that the adverse effects of prenatal maternal depression on problematic temperament were amplified by in utero Sandy exposure. This study underscores the importance of providing prenatal screening and treatment for maternal depression during pregnancy while also identifying high-risk families who may have suffered from disaster-related traumas to provide necessary services. As the frequency of natural disasters may increase due to climate change, it is important to understand the consequences of in utero stress on child development and to formulate plans for early identification. 相似文献
Nanoscale Cu-rich precipitates (CRPs) are one of the most important microstructural nano-features responsible for embrittlement and hardening of reactor pressure vessels (RPVs), which threaten the safe operation of nuclear power plants (NPPs) and hinder the lifetime extension of nuclear reactors. A thermally aged Fe-1.1 wt.%Cu alloy, which is used to simulate embrittlement of the irradiated RPV steels, was treated by electropulsing with various parameters. The effect of electropulsing on nanoscale CRPs was investigated by using transmission electron microscopy (TEM). Compared to the traditional heat treatment, the electropulsing treatment (EPT) can accelerate the dissolution of CRPs in an aged Fe-Cu alloy on account of the higher atomic drift flux and the additional Gibbs free energy induced by electropulsing. More importantly, EPT is likely to be a new way of eliminating irradiation-induced Cu-rich precipitates. 相似文献
In the marketing and consumer behavior literature, there has been a growing attention on upward intergenerational influences, or reverse socialization, which is largely because of children's increasing influences on family decisions. This paper hypothesizes different patterns of upward intergenerational influences in single versus multiple‐child families, controlling for peer and spousal influences. We found that young adult single children had a direct positive influence on their parents' innovation adoption behavior, but not a significant influence on their parents' overall innovativeness, whereas young adult children with siblings had a different effect: Their innovativeness had a significant positive influence on their parents' overall innovativeness, but not a direct impact on their parents' innovation adoption. 相似文献
Underprivileged children are a relatively special vulnerable group in rural China, but the relationship between poverty and children’s mental health has been rarely examined. This study aimed to investigate the effect of poverty on children’s mental health and the mediating role of social capital in their family, peer, school, and community level. Data used in this study were collected in 2015 from a school-based survey of 1314 children in grades 4–9 through a multi-stage cluster random sampling method in Xiushui, a poverty-stricken city in Mainland China. The result of structural equation modeling indicated that poverty elicited a significant predictive effect on children’s negative and positive mental health. Family social capital and peer social capital played intermediary effects between poverty and children’s mental health. However, the mediating effects of school and community social capital are not significant. The implications of these findings on theory, social policy, and social work services were also discussed.