Experimental and simulated grain boundary groove profiles in tungsten

Grain-boundary grooving has been studied on polished surfaces of polycrystalline tungsten annealed at 1350°C. Atomic force microscopy images were taken in the same area for each groove after different annealing times. Secondary oscillations next to the main groove maxima (predicted for grooving by surface diffusion) were observed, to our knowledge for the first time. The agreement between experimental and calculated groove profiles (using the surface diffusion model of Mullins (1957, J. appl. Phys., 28, 333)) improved when grain-boundary fluxes were introduced.     

Effect of aspect ratio on the compressive deformation and fracture behaviour of Zr-based bulk metallic glass

The compressive deformation and fracture features of Zr₅₉Cu₂₀Al₁₀Ni₈Ti₃ bulk metallic glassy samples with aspect ratios in the range of 0.67–2.00 have been investigated. The compressive plastic strain of the glass monotonically increases with decreasing aspect ratio, but the maximum strength almost maintains a constant value of 1.77–1.88?GPa. All the compressive shear-band angles are equal to?～40° if modified by the rotation of the primary shear bands.     

Understanding scale-dependent yield stress of metals at micrometre scales

The mechanical softening behaviour of micrometre-scale metals (free-standing metal foils and wires) with decreasing either the geometrical or the microstructural scale (i.e. the smaller, the weaker) has recently been reported. Here, we present a mechanism-based model to understand the softening behaviour, which is based on competition between the effects of surface grain relaxation and the interior grain strengthening effect. The model describes well the yield stress of Cu foils with different ratios of the thickness to grain size.     

Confidence in accuracy moderates the benefits of retrieval practice

ABSTRACT

The effect of Retrieval Practice refers to the phenomenon that taking a practice test is more effective for learning than re-study, probably due to the benefit from processes underlying successful retrievals during practice. However, it is rarely studied whether other processes (e.g., metacognitive monitoring) during retrieval practice may also play an important role. In two experiments, we examined whether the effectiveness of retrieval was affected by subjects’ confidence in their retrieval success. Subjects studied word-pairs and rated their confidence after each practice test trial (cued-recall in Exp.1, multiple choice in Exp.2), or re-study trial. In both experiments, we observed the classic retrieval practice effect. Moreover, in Exp.2, the benefits differed as a function of subjects’ confidence in their retrieval performance: the effect of retrieval practice only emerged for high-confidence trials with higher than 56% confidence. In summary, the retrieval practice only facilitates the retention of correct answers with high confidence.     

转化医学模式对临床医学八年制教学改革的启示

近年来我国部分重点医学院校陆续推出精英教育培养模式,以八年制医学生的培养为代表.临床医学八年制的培养更需要基础医学与临床医学之间相互整合,是完善“八年一贯,本博融通”培养模式的关键.转化医学的出现,为消除基础与临床的屏障,提高八年制医学生基础医学研究水平,加强临床思维培养提供了新的平台和途径.     

《管子》生态伦理思想及其当代启示

《管子》生态伦理思想具有丰富而深刻的内涵,“天人相分”与“天人合一”的天人观,“道为物要”与“德润万物”的伦理观,“人君天地”与“人与天调”的实践观。其深刻的精神理念对我们今天的生态文明建设具有重要的借鉴意义。这些启示我们应从强化生态意识、加强生态制度建设、实施行为生态化建设、坚持生态化修养建设等方面加强生态文明建设。     

情绪作为道德判断的“催化剂”：道德判断中的评价倾向与特异性效应

在不同领域的道德判断中,情绪可能起着“催化剂”的作用。一种特定情绪对应一种核心评价;一种情绪只影响某一道德领域的判断,不同情绪的影响是特异性的;进化心理学和具身认知对道德判断中存在的评价倾向和特异性效应进行了解释。未来研究需要探索评价倾向与特异性效应的内在心理机制。以及进一步探讨文化等第三变量对不同情绪与特定领域道德判断的影响。     

宗教研究的认知科学新取向

宗教认知科学是新近出现的从认知和进化的角度研究宗教的分支学科。主要有认知副产物和社会适应两种理论。认知副产物理论认为宗教信仰是人类认知倾向的副产物;社会适应理论认为宗教信仰促进群体的团结合作,是一个精巧的社会适应机制,有助于群体的自然选择。两种理论引发了系列的实验研究,由于宗教认知科学仍处于理论研究向实证研究的过渡阶段,未来需统一概念,加强实验范式的建立,更多地借助认知科学的方法和工具开展实证研究。     

一种多级评分的广义认知诊断模型

认知诊断是近些年教育测量研究中的热点,大多数的认知诊断模型仅适用于0～1评分的情况.本文提出一种有多个潜变量多个滑动参数的多级评分认知诊断模型——GP-D1NA,只要由评分标准和知识状态能确定理想反应模式,就可以利用此方法进行认知诊断分析.在该方法中,我们给出项目滑动矩阵的概念,将被试的观测得分均看成由某个理想得分的滑动,并采用EM算法估计滑动矩阵.在模拟研究中,采用每掌握一个属性得1分的评分标准,结果表明线性型、收敛型、发散型、无结构型和独立型五种属性层级结构均有较高的判准率.