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141.
Current methods of assessing children's emotional reactivity fail to capture individual differences in emotion across contexts that may be meaningfully related to youth psychopathology. We therefore explored the utility of modeling variability in young children's positive and negative emotion across emotionally evocative laboratory tasks to predict later adjustment. At age 3, 409 children completed a battery of laboratory tasks eliciting either positive or negative affect. We used latent difference score (LDS) modeling to predict children's caregiver-reported internalizing symptoms across ages 3, 5, 8, and 11 from variability in their observer-rated positive and negative emotion across laboratory tasks. We found that sex moderated the association between both average and variability measures of children's negative emotion at age 3 and trajectories of their anxious-depressive symptoms across childhood. Measures of emotion variability predicted children's internalizing symptoms above and beyond measures of average emotion. Variability indices also provided unique information about the trajectories of children's symptoms. We discuss implications for the utility of LDS modeling in assessing children's emotional reactivity.  相似文献   
142.
本文利用协整分析和误差修正模型,从长期和短期分析了人民币名义汇率和实际汇率分别与广东省外商直接投资之间的均衡关系。结果发现,从长期来看,人民币实际汇率的波动对外商直接投资的影响远大于名义汇率波动所带来的影响;而短期内则刚好相反。名义汇率和实际汇率的波动均是外商直接投资变化的原因:人民币汇率无论是名义贬值还是实际贬值都能够促进外商直接投资的流入。  相似文献   
143.
Human variability is a very important factor considered in human health risk assessment for protecting sensitive populations from chemical exposure. Traditionally, to account for this variability, an interhuman uncertainty factor is applied to lower the exposure limit. However, using a fixed uncertainty factor rather than probabilistically accounting for human variability can hardly support probabilistic risk assessment advocated by a number of researchers; new methods are needed to probabilistically quantify human population variability. We propose a Bayesian hierarchical model to quantify variability among different populations. This approach jointly characterizes the distribution of risk at background exposure and the sensitivity of response to exposure, which are commonly represented by model parameters. We demonstrate, through both an application to real data and a simulation study, that using the proposed hierarchical structure adequately characterizes variability across different populations.  相似文献   
144.
Archaeologists are increasingly interested in networks constructed from site assemblage data, in which weighted network ties reflect sites’ assemblage similarity. Equivalent networks would arise in other scientific fields where actors’ similarity is assessed by comparing distributions of observed counts, so the assemblages studied here can represent other kinds of distributions in other domains. One concern with such work is that sampling variability in the assemblage network and, in turn, sampling variability in measures calculated from the network must be recognized in any comprehensive analysis. In this study, we investigated the use of the bootstrap as a means of estimating sampling variability in measures of assemblage networks. We evaluated the performance of the bootstrap in simulated assemblage networks, using a probability structure based on the actual distribution of sherds of ceramic wares in a region with 25 archaeological sites. Results indicated that the bootstrap was successful in estimating the true sampling variability of eigenvector centrality for the 25 sites. This held both for centrality scores and for centrality ranks, as well as the ratio of first to second eigenvalues of the network (similarity) matrix. Findings encourage the use of the bootstrap as a tool in analyses of network data derived from counts.  相似文献   
145.
Research has shown that reinforcing novel behaviors can increase the number of different ways that an individual behaves (Goetz & Baer, 1973; Pryor, Haag, & O'Reilly, 1969). However, it was not until more recently that researchers began to consider variability to be a reinforceable operant in and of itself (Neuringer, 2002). More specifically, Neuringer suggested that variability can be taught using a Lag x schedule of reinforcement, in which x refers to the number of previous responses from which the current response must differ in order for reinforcement to occur (Page & Neuringer, 1985). The purpose of the present study was to extend one of the first studies of a Lag x schedule on verbal responses with human subjects (Lee, McComas, & Jawor, 2002), by increasing the lag criteria while attempting to address some of methodological limitations of the study. The participant was a 7-year-old male with autism. A changing criterion design was used and results showed that 3 novel responses were acquired and varied according to the lag schedule of reinforcement.  相似文献   
146.
Research has shown that variability may be an operant dimension of behavior. One method of reinforcing response variability is to use a lag schedule of reinforcement (Page & Neuringer, 1985). Several studies have shown that a Lag 1 schedule is effective in increasing variable responding with human participants (e.g., Esch, Esch, & Love, 2009; Lee, McComas, & Jawor, 2002). In these arrangements, however, the return to baseline responding during reversal phases suggests that the resulting behavior change may not be maintained following intervention. The purpose of the present study was to investigate the effects of a Lag 3 schedule on increasing and maintaining variability of tacts in 2 children diagnosed with developmental disabilities. Results demonstrated increased variability in tacting for both participants and maintenance in variable responding after a 3-week follow-up.  相似文献   
147.
本文分析了香港降水的变化、降水应以及降水的稳定性,从香港降水强度中分析香港暴雨的情况及其危害,并指出城市热岛效应使香港降水生产变化。  相似文献   
148.
We evaluated the effects of instructive feedback on the variability of intraverbal responses for two children with autism spectrum disorder. Specifically, we used an adapted alternating treatments design to compare participants’ novel responses and response combinations during an intraverbal category program across conditions with and without instructive feedback. During instructive feedback, secondary targets were presented during the consequence event of the learning trial and consisted of a therapist’s model of response variability. The results showed that participants engaged in more novel response combinations during instructive feedback conditions. We discussed the clinical implications of these results as well as areas for future research.  相似文献   
149.
为了对大学生学习成绩的长期变动性进行研究,将某专业299名学生按第一学期成绩排名分为1个5等分组,再将他们按大学毕业成绩排名分为第2个5等分组,观察2个5等分组间人员的流动情况并据此构建大学期间学生在2个5等分组间的成绩转移矩阵;在此基础上分析了每个等分组的成绩转移情况;计算了平均5等分组间的流动率、停留在同一5等分组的比率;与“数学意义上的完美转移矩阵”指标进行比较的结论是该专业学生大学期间成绩变动性不大。  相似文献   
150.
Shaping functional vocal language is difficult when an individual has not yet acquired an echoic repertoire and does not emit sufficient phonemes (i.e., speech sounds) for shaping. Few studies have evaluated interventions to increase the frequency and breadth of phonemes. The current study extended Esch, Esch, and Love (2009) by evaluating the effects of a Lag 1 reinforcement schedule on vocal variability and limiting the definition of variability to responses that incorporated a novel phoneme. For 2 of the 3 participants, the cumulative number of novel phonemes, the percentage of trials with variability, and the number of different phonemes emitted per session increased during the Lag 1 intervention phase.  相似文献   
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