A theoretical model of effective electrical conductivity and piezoresistivity of carbon nanotube composites

A theoretical model is developed to predict the electrical conductivity of polymer composites containing carbon nanotubes. It incorporates the effect of two conductivity mechanisms, electron hopping between adjacent nanotubes at the nanoscale and the transmission of electrons through conductive networks formed by nanotubes at the microscale. Based on the model, analytical expressions of both electrical conductivity and piezoresisitivity under stretching are established. The expressions are simple in form, without resorting to heavy computation, and able to give accurate estimations for both electrical conductivity and piezoresistivity.     

进化心理学对心理素质结构研究的整合与重构——以学生心理素质结构研究为例

传统的心理素质结构研究模式不经济,研究结果出现纵向断裂横向分裂的趋势.从进化心理学的视角来看,心理素质结构的最终功能均指向个体的适应性,其形成是与周围环境不断排斥和融合的过程.建构的心理素质结构融合模型能在一定程度上解决传统研究模式的弊端,并建议今后的研究应以分析人为主导转而分析人及其所处的文化环境并重,进而引导人的心理素质结构的不断发展.     

个体对效价预期和风险评估的时程加工机制:来自ERP的证据

采用事件相关电位技术(ERP),通过简单赌博任务,操纵结果预期的效价(输或赢)与风险(高风险与低风险),考察了个体对结果预期阶段的效价和风险评估的脑内时程动态加工过程。脑电结果发现:(1)在N2成分上,结果预期的效价主效应显著,预期输比预期赢能够引起更大的N2波幅;结果预期的风险主效应不显著。(2)在N500成分上,效价与风险之间的交互作用边缘显著,进一步简单效应分析发现,在预期输的条件下,肯定会输的N500波幅显著大于可能会输;而在预期赢的条件下,肯定会赢与可能会赢之间的N500波幅差异不显著。这说明,在不确定决策过程中的结果预期阶段,个体可能先对结果预期的效价进行加工,然后再对风险进行评估。     

论马克思主义的整体性(上)

近年来,随着 "马克思主义理论"被正式确立为国家一级学科,"马克思主义学院"在全国高等院校纷纷成立,国内马克思主义研究在表面上也呈现出一派热闹非凡的景象。于是马克思主义的整体性问题被提了出来。然而,与这种表面上热闹的景象形成鲜明对照的是,真正从心灵深处认同、信仰马克思主义的人并不很多。这种悖论式的现象不能不引起我们足够的重视。对于研究马克思主义的理论工作者而言,必须对眼前令人眼花缭乱的马克思主义 "热"进行 "冷"思考,就是说,必须认真地、郑重地提出并弄清这样一个问题: 马克思主义就其本义而言,是站在大众立场、为大众立言、为     

高职生因果定向与学业表现的关系

为了考察高职生因果定向的特点及因果定向与学生学业表现(学业成绩和专业技能)的关系。该研究以修订的一般因果定向量表为工具,在济南和淄博的三所高职抽取505名学生作为被试进行调查。结果发现:1)修订后的一般因果定向量表具有良好的信效度;2)高职生在因果定向的三个维度上得分差异显著,由高到低依次为自主定向、控制定向和非个人定向;3)自主定向显著正向预测学业表现,控制定向显著负向预测学业表现,而非个人定向对学业表现的预测作用不显著。我国高职生与国外被试的因果定向特点基本一致,说明因果定向具有一定的文化普适性。同时,不同因果定向对学业表现具有不同的预测作用,教育者有必要对学生进行因果定向的教育和引导。     

上行比较影响行为表现—不同类型高自尊的作用

已有研究表明,上行比较对高自尊个体产生积极效应。然而鉴于高自尊包括安全性高自尊和防御性高自尊,有必要在上行比较影响不同任务领域内的行为表现这一观点的基础上探讨高自尊的不同类型对上行比较与行为表现之间关系的影响。两个实验均采用高自尊类型、上行比较和任务领域一致性的2×2×2混合因素设计,不同之处在于其分别采用创造性测验和非创造性的语词测验作为不同领域任务。结果表明,防御性高自尊个体没有像安全性高自尊个体那样采取领域转换策略来修复自我关注,由上行比较所引起的领域转换只对安全性高自尊个体产生积极影响。     

幼儿提问类型及策略对其问题解决的影响

该研究以69名5岁幼儿为被试,通过创设猜测物体的问题情境,以考察幼儿提问对其解决猜测物体的问题的影响.结果表明:(1)面对问题情境,幼儿运用提问解决问题的正确率显著高于不提问直接猜测的正确率.(2)幼儿运用两阶段整体策略和逐一排除策略提问来帮助其问题解决的效果好于直接猜测的效果.(3)幼儿提出混合类问题和外在感知类问题来帮助其解决猜测物体问题的效果好于提出内在属性类问题.     

Stress induces glucocorticoid-mediated apoptosis of rat Leydig cells in vivo

Stress can disrupt endocrine signalling in the male reproductive axis through high concentrations of glucocorticoids, the hallmark of stress. Our previous work revealed that a stress level of exogenous glucocorticoids could induce apoptosis of rat Leydig cells, which are the primary source of testosterone. The aim of this study was to investigate whether stress can induce apoptosis in rat Leydig cells in vivo and, if so, whether the process is the result of a direct effect of glucocorticoids. In a chronically stressed rat model, serum corticosterone concentration was increased significantly whereas serum testosterone was decreased. The frequency of apoptotic Leydig cells in stressed rats was also increased. Adrenalectomised rats subjected to chronic stress showed an elevated serum testosterone, while the apoptotic frequency of Leydig cells was not increased. It was established that glucocorticoid-induced Leydig cell apoptosis is mediated by glucocorticoid receptors (GRs), which translocate from cytoplasm to nucleus. Adenovirus microRNA-induced downregulation of GR expression in vitro alleviated the corticosterone-induced increase in apoptosis of Leydig cells. These results indicate that the stress-induced increase in corticosterone secretion resulted in apoptosis in rat Leydig cells in vivo, and thereby decreased testosterone synthesis.     

Dopamine D1 receptors are responsible for stress-induced emotional memory deficit in mice

It is established that stress impairs spatial learning and memory via the hypothalamus-pituitary-adrenal axis response. Dopamine D1 receptors were also shown to be responsible for a stress-induced deficit of working memory. However, whether stress affects the subsequent emotional learning and memory is not elucidated yet. Here, we employed the well-established one-trial step-through task to study the effect of an acute psychological stress (induced by tail hanging for 5, 10, or 20?min) on emotional learning and memory, and the possible mechanisms as well. We demonstrated that tail hanging induced an obvious stress response. Either an acute tail-hanging stress or a single dose of intraperitoneally injected dopamine D1 receptor antagonist (SCH23390) significantly decreased the step-through latency in the one-trial step-through task. However, SCH23390 prevented the acute tail-hanging stress-induced decrease in the step-through latency. In addition, the effects of tail-hanging stress and/or SCH23390 on the changes in step-through latency were not through non-memory factors such as nociceptive perception and motor function. Our data indicate that the hyperactivation of dopamine D1 receptors mediated the stress-induced deficit of emotional learning and memory. This study may have clinical significance given that psychological stress is considered to play a role in susceptibility to some mental diseases such as depression and post-traumatic stress disorder.