A phase-field model for deformation twinning

We propose a phase-field model for modeling microstructure evolution during deformation twinning. The order parameters are proportional to the shear strains defined in terms of twin plane orientations and twinning directions. Using a face-centered cubic Al as an example, the deformation energy as a function of shear strain is obtained using first-principle calculations. The gradient energy coefficients are fitted to the twin boundary energies along the twinning planes and to the dislocation core energies along the directions that are perpendicular to the twinning planes. The elastic strain energy of a twinned structure is included using the Khachaturyan's elastic theory. We simulated the twinning process and microstructure evolution under a number of fixed deformations and predicted the twinning plane orientations and microstructures.     

Interactions of persistent slip bands with a grain boundary on the common primary slip plane in a copper bicrystal

In this letter, the dislocation patterns on the common primary slip plane in a fatigued \[1-34]-\[182-7] copper bicrystal with a Sigma=19b grain boundary (GB) have been investigated using the electron channelling contrast technique in a scanning electron microscope. The results show that the two-phase dislocation structure, such as veins and persistent slip band (PSB) walls, embedded within veins, can be clearly seen on the common primary slip plane. In particular, the interactions of PSBs with the GB are clearly revealed. It is found that there are three kinds of interaction mode between the GB and the dislocations during cyclic deformation, and those are discussed. It is suggested that the dislocations carried by PSBs cannot transfer through the GB continuously even though the bicrystal has a common primary slip plane and its surface slip bands are continuous across the GB.     

Crystallization behaviour of Al-based amorphous alloy and nanocomposites by rapid quenching

The microstructure and crystallization behaviour of melt-spun Al₈₈Ni₉Ce₂Fe₁ amorphous alloy and nanophase composites have been studied by means of X-ray diffraction, transmission electron microscopy and scanning and isothermal calorimetry. The diffraction patterns from Al₈₈Ni₉Ce₂Fe₁ amorphous alloys are diffuse, indicating a basically amorphous structure but contain two rings presumed to be associated with quenched-in nuclei. In the cases of Al₈₈Ni₉Ce₂Fe₁ nanophase composites, nanoscale precipitated particles are homogeneously dispersed in an amorphous matrix, and the crystallite diameter and volume fraction are sensitive to quenching conditions. During thermal crystallization, a two-step phase transformation occurs in the amorphous alloy and nanocomposites, which is characterized by a diffusion-controlled precipitation of nanoscale Al particles and the growth of a Al₃(Ni, Fe) nanophase prior to a Al₁₁Ce₃ nanophase. This study gives insight into structure-control for obtaining nanophases dispersed in an amorphous matrix by rapid quenching.     

Burnout and its relations with basic psychological needs and motivation among athletes: A systematic review and meta-analysis

ObjectivesThe present study is a review on studies about the relationships between the three basic psychological needs/motivational regulations (i.e., amotivation, controlled regulation, extrinsic autonomous regulation, and intrinsic motivation) and burnout.DesignA systematic review and meta-analysis.MethodStudies were identified through five electronic databases and manual search using combinations of three groups of keywords. Three inclusion criteria were then used to screen the searched articles.ResultsEighteen studies met the inclusion criteria and these studies varied considerably in terms of their study characteristics (e.g., characteristics of participants, study designs, and outcome measures). The results also showed that the three basic psychological needs, intrinsic motivation, extrinsic autonomous regulation, and amotivation had small to large effects on predicting global burnout and its three dimensions. However, controlled regulation showed no or weak correlations with the burnout subscales.ConclusionsSelf-determination theory was generally supported in explaining athlete burnout.     

Cognition and Emotion in TV Message Processing: How Valence,Arousing Content,Structural Complexity,and Information Density Affect the Availability of Cognitive Resources

This paper examines whether emotional message content alters the effects of structural complexity and information density on available resources, measured by secondary task reaction times (STRTs), and message encoding, measured by audio recognition. In addition, hypotheses relating motivational activation and resource availability based on the motivational activation concepts of positivity offset (greater appetitive activation in a neutral environment) and negativity bias (faster aversive activation) influence are tested. Results replicate previous research supporting the contention that STRTs measure available resources. In addition, they show that the basic pattern of STRTs and recognition as a function of allocated and required resources is relatively consistent regardless of emotional content of the message. Emotion appears to function as a constant, increasing both resource allocation and resources required. Finally, these data provide some initial support for predicted relationships between motivational activation and resource allocation based on the constructs of positivity offset and negativity bias.     

Uptake of Cardiac Screening and Genetic Testing Among Hypertrophic and Dilated Cardiomyopathy Families

Cardiomyopathy is a genetically and clinically heterogeneous, life threatening disease which affects people of all ages. Recent guidelines provide recommendations for cardiac screening and genetic testing in at-risk relatives, but the uptake and impact of these measures in the United States is unknown. This is a single institution retrospective study that characterizes the uptake of cardiac screening and genetic testing for relatives of a cohort of 57 probands with hypertrophic (HCM) and dilated cardiomyopathy (DCM) who underwent both clinical evaluation and genetic testing. Cardiac screening was indicated for 302 relatives. One hundred and seventy-three (57 %) completed cardiac screening. Forty of the 57 probands were mutation positive and genetic testing was indicated for 213 relatives. Eighty-four (39 %) completed genetic testing. The uptake of cardiac surveillance was greater than the uptake of genetic testing (p?<?0.0001) among relatives of mutation positive probands. Within the group of at-risk, asymptomatic relatives of probands, cardiac screening and genetic testing were positive in 25 % and 40 % of cases, respectively. These data demonstrate the important role and utility of cascade cardiac screening and genetic testing in the care of patients and families with HCM or DCM. The approach to cardiac screening and genetic testing should be family-specific and requires expertise in the genetics of cardiomyopathy.     

Coping mediates between social support,neuroticism, and depression after earthquake and examination stress among adolescents

Abstract

The objective of this study was to investigate the mediating role of coping strategies in the relationships between neuroticism, social support, and depression in two groups of adolescents: earthquake group and examination group. Adolescents facing earthquake stress (earthquake group, N=219) completed measures of neuroticism, perceived social support, coping strategies, and self-rating depression. Similarly, adolescents facing examination stress (examination group, N=241) completed the same measures. Results indicated that the earthquake group reported more use of secondary control engagement coping, whereas the examination group reported more use of primary control engagement coping. In addition, neuroticism was more strongly associated with coping in earthquake group and coping strategies explained significantly larger part of the relationship between neuroticism and depression. In contrary, perceived social support was more strongly associated with coping in examination group, and coping strategies explained significantly larger part of the relationship between perceived social support and depression.     

Learning Impacts of a Digital Augmentation in a Science Museum

ABSTRACT

This study investigated the effects of using digital augmentation to enhance an exhibit device to influence conceptual understanding about a science topic in a science museum setting. In particular, the study considered how students in Grades 6–8 engaged with the device that was available in both augmented and nonaugmented (control) conditions. Results show increased cognitive (critical thinking) skills when the digital augmentation was present that we hypothesize led to increased conceptual gains. We illustrate how this research contributes to three important areas of need identified in informal science literature: the need for evidence of conceptual and cognitive gains; the need for understanding how digital platforms improve the learning experience; and the need to demonstrate how designed interactive devices may impact higher order skills such as critical thinking and theorizing.