Tensile deformation mechanisms of the hierarchical structure consisting of both twin-free grains and nanotwinned grains

A series of large-scale molecular dynamics simulations have been performed to investigate the tensile properties and atomistic deformation mechanisms for the nanostructured Cu with three typical microstructures: the hierarchical structure consisting of both twin-free grains (d?=?70?nm) and grains with bundles of smaller nanotwins (d?=?70?nm, λ?=?10?nm), the fully nanograined structure and the fully nanotwinned structure. The average flow stress of the hierarchically structure is found to be higher than that calculated by rule of mixture. As compared with that of fully nanograined structure, the strength for the twin-free grains in the hierarchical structure is promoted and gives extra hardening due to the increased dislocation density and dislocation behaviours. It is also found that the nanotwin bundles are more deformable than the twin-free grains in the hierarchical structure according to the deviatoric strain invariant contour. This indicates that the fully nanograined structure cannot only be strengthened to a higher level, but also obtain better ductility by embedded with stronger bundles of smaller nanotwins. Thus, a superior strength–ductility synergy could be obtained in this kind of hierarchical structures, and this novel strategy has also been implemented in bulk austenitic steels or copper by recent experiments.     

Understanding youth antisocial behavior using neuroscience through a developmental psychopathology lens: Review,integration, and directions for research

Youth antisocial behavior (AB) is an important public health concern impacting perpetrators, victims, and society. Functional neuroimaging is becoming a more common and useful modality for understanding neural correlates of youth AB. Although there has been a recent increase in neuroimaging studies of youth AB and corresponding theoretical articles on the neurobiology of AB, there has been little work critically examining the strengths and weaknesses of individual studies and using this knowledge to inform the design of future studies. Additionally, research on neuroimaging and youth AB has not been integrated within the broader framework of developmental psychopathology. Thus, this paper provides an in-depth review of the youth AB functional neuroimaging literature with the following goals: (1) to evaluate how this literature has informed our understanding of youth AB, (2) to evaluate current neuroimaging studies of youth AB from a developmental psychopathology perspective with a focus on integrating research from neuroscience and developmental psychopathology, as well as placing this research in the context of other related areas (e.g., psychopathy, molecular genetics), and (3) to examine strengths and weaknesses of neuroimaging and behavioral studies of youth AB to suggest how future studies can develop a more informed and integrated understanding of youth AB.     

Regulation of brain activity in the fusiform face and parahippocampal place areas in 7–11-year-old children

Developmental studies have demonstrated that cognitive processes such as attention, suppression of interference and memory develop throughout childhood and adolescence. However, little is currently known about the development of top-down control mechanisms and their influence on cognitive performance. In the present study, we used functional magnetic resonance imaging to investigate modulation of activity in the ventral visual cortex in healthy 7–11-year-old children and young adults. The participants performed tasks that required attention to either face (Fs task) or scene (Sf task) images while trying to ignore distracting scene or face images, respectively. A face-selective area in the fusiform gyrus (fusiform face area, FFA) and an area responding preferentially to scene images in the parahippocampal gyrus (parahippocampal place area, PPA) were defined using functional localizers. Children responded slower and less accurately in the tasks than adults. In children, the right FFA was less selective to face images and regulation of activity between the Fs and Sf tasks was weaker compared to adults. In the PPA, selectivity to scenes and regulation of activity, there according to the task demands were comparable between children and adults. During the tasks, children activated prefrontal cortical areas including the middle (MFG) and superior (SFG) frontal gyrus more than adults. Functional connectivity between the right FFA and left MFG was stronger in adults than children in the Fs task. Children, on the other hand, had stronger functional connectivity than adults in the Sf task between the right FFA and right PPA and between right MFG and medial SFG. There were no group differences in the functional connectivity between the PPA and the prefrontal cortex (PFC). Together the results suggest that, in 7–11-year-old children, the FFA is still immature, whereas the selectivity to scenes and regulation of activity in the PPA is comparable to adults. The results also indicated functional immaturity of the PFC in children compared to adults and weaker connectivity between the PFC and the rFFA, explaining the weaker regulation of activity in the rFFA between the Fs and Sf tasks.     

Interactive Elicitation and Exchange of Knowledge

This paper gives a state-of-the-art report on the use of techniques based on personal construct psychology to automate interactive elicitation of cognitive structures for group learning and decision making. It outlines the structure and key components of the RepGrid implementation on a network of Macintosh computers, which includes tools for interactive reperto y grid elicitation and analysis, and a system for intemctizely exchanging and comparing reperto y grids from multiple simultaneous users on the network. The users of RepGrid are attempting to extend and understand their own thinking and problem-solving capabilities by interacting w'th other people. They are able to: see the relationship of thrir points of view to those of others explore differing termin, logy for the same constructs become aware of differing constructs having the same terminology extend their own construct systems with those of others provide others with constructs they have found valuable explore a problem-solving domain using the fill group resources     

青少年早期抑郁的自尊缓解假设的追踪研究

本研究采用追踪设计和青少年自我报告法,以初一年级598名青少年为研究对象,运用分层多元回归分析,考察其自尊缓解生活事件对抑郁的影响是否随自尊与抑郁之间的时间间隔而异。发现当前自尊显著缓解压力事件对抑郁的即时作用和长期作用;先前自尊不能显著缓解先前压力事件对抑郁的长期作用,反而加剧压力事件的长期作用。这些发现对青少年抑郁的干预将有重要启示。     

Group Cohesion,Achievement Motivation,and Motivational Outcomes among Female College Students

Embedded in the theory of group cohesion and the expectancy-value model of achievement choice, the purpose of this study was to examine the predictive strengths of group cohesion on students’ motivation (expectancy-related beliefs and subjective task values) and motivational outcomes (exercise choice and class attendance) in college physical activity classes. Participants were 121 females enrolled in aerobics classes who completed questionnaires assessing group cohesion, motivational constructs, and exercise choice. Group cohesion constructs were significantly associated with motivation and motivational outcomes. These findings provide insight into how to design environments to promote motivation in physical activity classes.     

Banking on brains: Insights of brain donor relatives and friends from an experiential perspective

Brain donation is critical to understand the pathological causes of neurodegenerative diseases. Increasing levels of donation requires an understanding of those factors that both encourage and deter donation. At present, there are few studies of how people understand, feel and decide about brain donation for scientific research. This qualitative experiential study contributes to the growing literature on brain donation through its specific focus on how the donation process is experienced from the perspectives of family members and friends. Nineteen semi-structured interviews were analysed using a phenomenologically informed thematic analysis. Four themes were derived from the analysis, three of which are described in detail: Making the decision to donate; a personal perspective on the donation process; the significance of the brain; beliefs about brain donation. In particular, the thematic analysis highlights the variation of individual decision making and the emotions and reasons underpinning such decisions. Key conclusions include the importance of integrated practice amongst relevant healthcare professionals as well as the need for supportive and informed communication. Also, in light of the finding that the brain assumed no special significance for most participants, the value of the distinction between brain donation for research purposes and organ transplantation is questioned.