Microstructure evolution of Al-15% Si alloy during hot rolling

ABSTRACT

A direct chill (DC) cast Al-15% Si alloy was processed by hot rolling with a single pass at a temperature of 520°C with a thickness reduction of 80%. Scanning electron microscopy (SEM), electron backscattering diffraction (EBSD) and transmission electron microscopy (TEM) were used to investigate the evolution of the sample’s microstructure. After hot rolling, silicon particles homogeneously distributed in the Al matrix with fine equiaxed grains of average size ～ 0.95?μm. High-angle boundaries (HABs) (about ～75.8% in percentage) dominate in the Al matrix structure. There is evidence for Si-particle-stimulated continuous dynamic recrystallization (CDRX) during hot rolling.     

儿童注意缺陷多动障碍(ADHD)的“冷”“热”执行功能

近30多年来,对注意缺陷多动障碍(ADHD)的认知缺损机制的关注一直停留在"冷"执行功能领域,为更全面地揭示其执行缺损机制,文章旨在从"冷""热"执行功能的角度来探讨ADHD的缺陷。论文简要回顾了注意缺陷多动障碍的界定、生理基础和若干理论模型,着重阐述ADHD儿童在经典"冷""热"两类执行功能任务上的表现差异。总结认为ADHD儿童并非在所有类型的"热"执行任务上表现落后,ADHD儿童的表现要视情感和动机的卷入对不同任务情景的作用性质是消极还是积极而定,文章也比较分析了几位研究者相关的理论解释。     

Multiple causal pathways in attention-deficit/hyperactivity disorder – Do emerging executive and motivational deviations precede symptom development?

The multiple causal pathways model on the etiology of attention-deficit/hyperactivity disorder (ADHD) is well established. However, developmental implications of the model are not yet sufficiently analyzed. The model implies that critical neural and neuropsychological deviations from normative development precede secondarily developing ADHD symptoms. Cognitive, “cool” inhibitory control (CIC) and reward-related, “hot” functions (RRF) are regarded as neuropsychological basic deficits that indicate independent causal pathways. Both functions involve top-down control networks that undergo major normative developmental changes in the preschool period. We formalized the following assumptions in a path model: (a) CIC and RRF predict change in ADHD symptoms in the preschool period, (b) the reverse is not true, and (c) CIC and RRF independently contribute to this prediction. A community-based sample of 125 (71 boys) preschoolers was assessed at at age 4 and 5 years. At each assessment wave, CIC and RRF were measured by a battery of age-appropriate valid tasks. ADHD symptoms were measured by a clinical parent interview. Evaluation of model fit using manifest maximum likelihood parameter estimation clearly supported the hypothesized path model while controlling for gender of child and maternal education level. Thus, regarding the basic deficits of CIC and RRF, the results add evidence on the developmental implications of the multiple causal pathways model. Our findings point to the potential significance of these early emerging characteristics as indicators of risk and as targets for preventive interventions.     

从儿童赌博任务看热执行功能的发展

为考察热执行功能的发展,本研究通过儿童赌博任务检测了60名3～4岁儿童(男女各半)的情感决策。实验结果表明,3岁和4岁儿童在此任务上存在显著的年龄差异,4岁组在各试验组的分数呈上升趋势,他们在试验组2、尤其在试验组4和5中选择有利纸牌的次数显著多于3岁儿童,这反映出情感决策在3～4岁期间发展迅速。此外,儿童在此任务上的成绩存在很多可变性,可能掩盖了性别差异,因而,尽管男孩在最后两个试验组的成绩优于女孩,但性别差异在统计上并不显著。     

热手谬误和赌徒谬误心理机制研究述评

在知觉随机序列时,人们倾向于把序列中实际上各自独立的相邻结果看作是存在正相关或负相关的,而出现热手谬误或赌徒谬误,又称为随机序列中的正负近因效应。有关这两谬误最早的心理机制的探索中,Kahneman 和Tversky采用局部代表性启发法对此进行了解释。但是这种解释也存在诸多不足,因此近期的一些模型（因果模型、Urn模型、记忆模型、适应模型和两阶段格式塔模型）分别从不同角度对两种谬误提出了新的解释。最后文章指出研究方法、神经机制、个体差异以及生活中的应用是该领域研究的几个未来发展方向     

攻击行为实验研究范式的回顾与展望

本文对攻击行为的经典实验研究范式——攻击机器法、文章评价法、竞争性反应比赛、减点——攻击测验、Bobo模仿范式等进行了回顾,并介绍了最新的研究范式--辣酱分配法、糟糕程序法、实验室涂鸦法等,最后对已有范式进行了总结与展望。     

“热”执行对注意缺陷多动障碍和阅读障碍儿童言语工作记忆的影响

ADHD儿童在与背外侧前额叶(DLPFC)相关的"冷"执行功能上的缺陷已大量证实,但在与眼眶和中前额叶皮层(OMPFC)相关的"热"执行功能上,ADHD儿童是否存在缺陷则未可知。与儿童赌博任务实验范式(该任务中"热"启动对"冷"执行起到抑制作用)不同,本研究考察趣味言语N-back任务是否对ADHD和阅读障碍儿童的成绩有促进作用。枯燥N-back任务考察的是言语工作记忆的纯认知特征,而趣味任务则卷入了"热"执行对"冷"执行的影响。结果表明,在枯燥任务上,ADHD和阅读障碍儿童的成绩均明显低于正常儿童,二者之间差异不显著,在趣味任务成绩上,ADHD儿童与正常儿童的成绩没有显著差异,而阅读障碍儿童成绩落后于正常控制组和ADHD组,在成绩变化的趋势上,ADHD儿童在趣味任务上成绩明显提高,而阅读障碍儿童则无明显改善。结果说明ADHD和阅读障碍儿童的言语工作记忆均存在明显的缺陷,但是机制不同,"热"执行对提高ADHD的言语工作记忆有明显的促进作用,ADHD的"冷"执行缺陷能够通过"热"执行的调节得到改善。     

米契尔关于满足延宕的研究

满足延宕是非常重要的自我控制行为,本文主要介绍米契尔在这方面的研究,涉及到了满足延宕的研究模式、影响个体做出延宕选择的因素、注意转移和认知表征对延宕过程的影响、儿童关于延宕的元认知发展、早期延宕行为与多年后个体的认知能力、社会应对技能的相关性研究、双重系统结构的理论,并分析了米契尔的研究对当今儿童教育的启示。     

Motivated reasoning in the prediction of sports outcomes and the belief in the “hot hand”

The present paper explores the role of motivation to observe a certain outcome in people’s predictions, causal attributions, and beliefs about a streak of binary outcomes (basketball scoring shots). In two studies we found that positive streaks (points scored by the participants’ favourite team) lead participants to predict the streak’s continuation (belief in the hot hand), but negative streaks lead to predictions of its end (gambler’s fallacy). More importantly, these wishful predictions are supported by strategic attributions and beliefs about how and why a streak might unfold. Results suggest that the effect of motivation on predictions is mediated by a serial path via causal attributions to the teams at play and belief in the hot hand.     

Individual differences in the rejection-aggression link in the hot sauce paradigm: The case of rejection sensitivity

Prior research shows that social rejection elicits aggression. In this study, we investigated whether this effect is moderated by individual differences in Rejection sensitivity (RS)—a processing disposition to anxiously expect, readily perceive and overreact to rejection. Participants (N = 129) took part in a purported web-based social interaction in which they were either rejected or not by a potential partner. Subsequently, they were given the opportunity to allocate hot sauce to the perpetrator, knowing that he/she disliked spicy food. Amount of hot sauce was used as a behavioral index of aggression. Participants in the rejection condition allocated more hot sauce to the perpetrator than those in the control condition. However, RS moderated this effect such that rejection elicited aggression in high but not in low RS people. These results held after controlling for trait neuroticism. Implications of these findings for understanding how and why rejection elicits aggression are discussed.