Linear instability signals the initiation of motion of a twin plane under load

This letter presents a study of the atomic mechanism of the initiation of motion of a static twin plane under applied mechanical load in a model shape-memory material. By tracking the deformation under load and using linear stability analysis, we find that the eigenvalues of the Hessian matrix provide an indicator of the initiation of motion of the twin plane. The initiation of motion is signaled by a linear instability and a drop in the lowest eigenvalue to zero as well as a sharp drop in higher eigenvalues. Additionally, by comparing with direct molecular dynamics, we see that the eigenmode associated with the zero eigenvalue is found to accurately predict the initial mode of motion. We also find that the initial motion occurs through the formation of a stacking fault just ahead of the existing twin plane and the broadening of the stacking fault drives further transformation.     

生物制剂治疗克罗恩病进展

克罗恩病是一种以累及消化道为主的复发性炎性疾病.生物制剂的使用为克罗恩病的治疗提供了新的方向.大量临床研究已证实生物治疗主要是抗TNF α单抗对诱导及维持克罗恩病临床缓解、预防并发症的发生有效.目前临床指南多建议对克罗恩病采取递增方案治疗,对重度患者可及早采取更为有效的包括生物治疗在内的治疗方式,但递减治疗方案在临床中的应用尤其是针对初次诊断者也越来越受到重视.目前早期及长期应用生物治疗的安全性及其是否能改变克罗恩病的自然病程证据尚不充分.应针对患者的不同情况,根据风险/效益研究来确定更合适的治疗方案.     

Formation and structure of misfit dislocations at the La2Zr2O7-Y2O3 -stabilized ZrO2 (001) reaction front during vapour-solid reaction

La₂ Zr₂ O₇ (LZO)-based pyrochlore islands were grown on a Y₂ O₃ -stabilized ZrO₂ (YSZ) (001) single-crystal surface by the reaction between La₂O₃ vapour and the crystal. A network of interfacial edge dislocations with line directions [100] and [010] and Burgers vectors ( a_s/2)[101] and ( a_s/2)[011] respectively ( a_s being the lattice parameter of the YSZ) was observed at the moving LZO-YSZ reaction front. The interface-parallel component of the Burgers vectors accommodates the LZO-YSZ lattice mismatch of +5.0%, while the perpendicular component causes a slight tilt of the LZO lattice with respect to the YSZ lattice. The dislocation half-loops nucleate and glide on inclined {101} planes at the edges of the four corners of the growing islands.     

Fractals and scaling in fracture induced by microcrack coalescence

A numerical model is proposed to simulate fracture induced by the coalescence of numerous microcracks, in which the condition for coalescence between two randomly nucleated microcracks is determined in terms of a load-sharing principle. The results of the simulation show that, as the number density of nucleated microcracks increases, stochastic coalescence first occurs followed by a small fluctuation, and finally a newly nucleated microcrack triggers a cascade coalescence of microcracks resulting in catastrophic failure. The fracture profiles exhibit self-affine fractal characteristics with a universal roughness exponent, but the critical damage threshold is sensitive to details of the model. The spatiotemporal distribution of nucleated microcracks in the vicinity of critical failure follows a power-law behaviour, which implies that the microcrack system may evolve to a critical state.     

个人幸福指数-中小学生版(PWI-SC)在中国的适用性——兼与澳洲中学生比较

探讨个人幸福指数-中小学生版(PWI-SC)在中国的适用性以及中澳两国中学生个人幸福指数的跨文化差异。采用PWI-SC施测522名中国中学生、185名澳洲中学生,进行区分度、信度和效度检验,发现该问卷可运用于中国中学生个人幸福指数的调查,个别项目需稍加修改。比较中澳中学生的施测结果,中国中学生的个人幸福指数低于澳洲中学生,中国中学生得分为47-70,澳洲中学生得分为51-72;中国中学生除在个人已有成就项目上得分高于澳洲中学生外,其他方面均较低;中澳两国初中生的个人幸福指数均显著高于高中生,两国初高中生个人幸福指数的差异体现在不同方面;中澳两国中学生个人幸福指数的年龄差异均显著,进一步事后分析发现,两国中学生个人幸福指数的基本趋势均为随年龄增长,个人幸福指数降低,中国15岁中学生的个人幸福指数较高。PWI-SC基本适用于中国中学生;中学生随年龄增长,个人幸福指数降低;中国中学生的个人幸福指数低于澳洲中学生。     

Perceiving and Interacting Affordances: A New Model of Human–Affordance Interactions

This article introduces a new affordance framework for humans and human design. Based on previous important concepts in product design–affordance, signifier, and product semantics, the authors propose three new concepts to illustrate how people perceive affordance. According to the model, perceptual probability of affordance is the probability that the public can perceive a certain affordance; perceptual threshold of affordance is the threshold at which affordance can be perceived by a person and changed by perceptual information; and situations, in which interactions between affordances and people exist, are crucial influences on human–affordance interactions. An illustration of the model and suggestions for further research are provided.     

Managerial Stress in Greater China: The Direct and Moderator Effects of Coping Strategies and Work Locus of Control

La présente étude examine les effets directs et modérateurs des stratégies de défense (contrôle et support) et de la perception de contrôle au travail (extérieure) sur des relations stresseur-tension entre des gestionnaires de la grande Chine (la République populaire de Chine, Hong Kong, et Taiwan). Les données ont été recueillies, via un questionnaire autoadministré, auprès de 876 gestionnaires soit 249 (164 hommes, 85 femmes) en République populaire de Chine, 280 à Hong Kong (159 hommes, 120 femmes, 1 non classifié), et 347 (191 hommes, 151 femmes, 5 non classifiés) au Taiwan. Des effets directs et modérateurs pour les stratégies de défense et pour la perception de contrôle ont été démontrés pour quelques relations stresseur-tension dans les divers échantillons étudiés.
The present study aims at examining the direct and moderator effects of coping strategies (control and support coping) and work locus of control (externality) on the stressor-strain relationships among managers in Greater China (the People's Republic of China [PRC], Hong Kong, and Taiwan). A self-administered survey method was employed to collect data from 249 (164 male, 85 female) managers in the PRC, 280 (159 male, 120 female, 1 unclassified) managers in Hong Kong, and 347 (191 male, 151 female, 5 unclassified) managers in Taiwan. The direct and moderator effects of control coping, support coping, and work locus of control on some stressor-strain relationships were demonstrated in the studied samples.     

语篇阅读中高级目标推理的机制

建构主义理论和最小假设模型是有关推理研究的两个比较系统的理论。建构主义理论认为在自然阅读过程中,读者会即时产生高级目标推理,而最小假设模型认为在自然阅读过程中,高级目标推理不会即时产生。该研究采用词汇判断和命名的方法,250ms和500ms两种延时程序,以较连贯的自然语篇为实验材料,对语篇阅读中的高级目标推理机制进行了研究。实验结果发现,被试在阅读过程中即时产生了高级目标推理,这与建构主义理论的预测相一致。