Log-normal nanograin-size distributions in nanostructured composites

A key challenge in the fabrication of superhard nanocomposite films is how to control the distribution of grain sizes in these materials. High-resolution transmission electron microscopy has been used to measure nanograin-size distributions in the Ti–B–N films with various B contents. The results show that the mean grain size decreases with increase of B content and the grain-size distribution conforms to a log-normal function when the hardness approaches a maximum value. The transition from normal to log-normal distributions can be determined by analysis in terms of a minimum information criterion. The origin of a log-normal size distribution probably results from heterogeneity arising from a diffusion-drift process.     

Mechanical-milling-induced amorphization of Se: A crystallite destabilization model

Complete solid-state amorphization has been realized in elemental Se by means of mechanical milling of crystalline Se powder. Quantitative X-ray diffraction and thermal analyses were employed to characterize the amorphization process and indicated that the amorphization onset corresponds to a critical crystallite size and a drop in microstrain. During the major amorphization process, the remaining crystallite size remains unchanged with a constant lattice expansion. A new kinetics model of crystallite destabilization is proposed for the solid-state amorphization which satisfactorily explains the experimental observations.     

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.     

Stemming the tide: Predicting women engineers' intentions to leave

This investigation adapts and extends the Social Cognitive Career Theory (SCCT) by integrating it with central constructs from turnover theory. The extended model proposes that domain specific self-efficacy and outcome expectations predict job satisfaction and organizational commitment — the two key job attitudes that have been established as influential predictors of turnover cognitions and behaviors. Further, we proposed that one form of organizational supports, specifically developmental opportunities at work, are sources of self efficacy and outcome expectations, and that the relationship between organizational supports and job attitudes is mediated by self-efficacy and outcome expectations. The proposed model was tested on a national sample of 2,042 women engineers. Overall, the results provided support for our newly developed model. Implications for theory, research, and practice are discussed.     

A Probabilistic Approach to Conditional Reasoning Development

How likely is the glass to break, given that it is heated? The present study asks questions such as this with or without the premise if the glass is heated, it breaks. A reduced problem (question without premise) measures the statistical dependency (conditional probability) of an event to occur, given that another has occurred. Such statistical dependency represents knowledge-based reasoning (inferring from “glass heated” to “its breaking”) and is a component of the response to the complete problem (question with premise). The complete problems therefore measure not only knowledge-based reasoning in terms of statistical dependencies (inductive component) but assumption-based reasoning (deductive component). Two experiments revealed: a) Knowledge-based reasoning continues to develop and attains adult levels at 7th grade for the problems tested, and b) assumption-based reasoning (deductive component) is reliable only for secondary school students (7th graders).     

Mapping the time course of the positive classification advantage: An ERP study

The aim of the present study was to investigate the time course of the positive advantage in the expression classification of faces by recording event-related potentials (ERPs). Although neutral faces were classified more quickly than either happy or sad faces, a significant positive classification advantage (PCA)—that is, faster classification for happy than for sad faces—was found. For ERP data, as compared with sad faces, happy faces elicited a smaller N170 and a larger posterior N2 component. The P3 was modulated by facial expressions with higher amplitudes and shorter latencies for both happy and neutral stimuli than for sad stimuli, and the reaction times were significantly correlated with the amplitude and latency of the P3. Overall, these data showed robust PCA in expression classification, starting when the stimulus has been recognized as a face revealed by the N170 component.     

Prevalence and Predictors of Posttraumatic Growth in Accidentally Injured Patients

This study examined prevalence and predictors of posttraumatic growth in 180 accidentally injured patients of mainland China in their convalescence stage, investigating its relationships with demographic and accidental injury variables, personality, posttraumatic stress disorder (PTSD) symptoms, and coping styles. Our results showed that posttraumatic growth (PTG) presented mostly in the domain of Relating to Others and indicated that PTG was significantly related to marital status, educational level, personality, coping styles, and PTSD symptoms. Avoidance of PTSD symptoms, Openness to experience, and positive coping were significant predictors of PTG. The findings emphasize that when promoting PTG of accidentally injured patients, healthcare providers should facilitate patients utilizing personal resources, understand PTG coexists with PTSD symptoms, and adjust interventions based on the coping styles the patients have adopted.     

Masked-target recovery requires focused attention on the target object

Flashing a homogeneous light mask after the presentation of a masked target reduces the deleterious effects of the mask, a phenomenon often called target recovery. Target recovery has been studied using masking paradigms in which a target object is presented in isolation prior to the presentation of a mask, thus capturing attention. In the present study, we examined whether target recovery is possible when a target does not benefit from attentional capture. We hypothesized that target recovery would be eliminated when a target must compete with distractors for perceptual attention. Replicating classic studies, we observed target recovery when pattern and light masks followed an isolated target. However, target recovery was not observed when a light mask followed a masked visual search target. Furthermore, using an attentional-capture paradigm we found that sudden onset search targets were recoverable whereas nononset targets were not. The present findings indicate that attentional capture by a target prior to masking plays a critical role in the subsequent recovery of the target.     

Exercise type relates to inhibitory and error processing functions in older adults

ABSTRACT

This study investigated the association between exercise type and inhibition of prepotent responses and error detection. Totally, 75 adults (M = 68.88 years) were classified into one of three exercise groups: those who were regular participants in open- or closed-skill forms of exercise, and those who exercised only irregularly. The participants completed a Stroop and task-switching tasks with event-related brain potentials (ERPs) recorded. The results revealed that regular exercisers displayed faster reaction times (RTs) in the Stroop task compared with irregular exercisers. The open-skill exercisers exhibited smaller N200 and larger P300a amplitudes in the Stroop task compared with irregular exercisers. Furthermore, the open-skill exercisers showed a tendency of shorter error-related negativity latencies at the task-witching test. The findings suggest that older adults may gain extra cognitive benefits in areas such as inhibition functioning and error processing from participating in open-skill forms of physical exercises.     

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。