Surface effect on the screw dislocation mobility over the Peierls barrier

The effect of the image force on the Peierls stress (τ _p ) of a screw dislocation below a free surface is studied via a self-consistent semidiscrete variational Peierls–Nabarro model. The consequence of reduction in elastic energy and increase in stacking fault energy by the presence of the free surface is found to additively increase the Peierls stress (τ _p ). This model gives a physical interpretation of the same tend observed in a recent molecular dynamic study, while previous continuum analysis predicted the opposite.     

Nature of ferroelectric–paraelectric transition

Ferroelectric (FE) materials directly convert electrical energy to mechanical energy and are critical to applications such as sensors, transducers, and actuators. The giant electromechanical response is the manifestation of the critical point between the first-order and second-order ferroelectric–paraelectric (FE–PE) transitions. For the simple classic FE lead titanate (PbTiO₃), it is commonly accepted that there is a critical point in the temperature–pressure phase diagram separating the first- and second-order FE–PE transitions at zero electric field. Here, we show that the FE-PE transition in PbTiO₃ is second-order at zero electric field. We introduce the concept of the invariant critical points (ICP) among three phases, representing the stability of the PE phase with respect to two FE phases in a three-dimensional electric field-pressure-temperature phase diagram of PbTiO₃. It is pointed out that the electromechanical response near ICPs is larger than that near the line of critical end points (LCEPs) between two phases.     

Shear vibration of a crystal plate carrying an array of microbeams

We study shear vibration of a rotated Y-cut quartz crystal plate carrying an array of microbeams with their bottoms fixed to the top surface of the plate. The beams undergo flexural vibrations when the plate is in shear motion. The plate is modeled by the theory of anisotropic elasticity. The beams are modeled by the Euler–Bernoulli theory for beam bending. A frequency equation that determines the resonant frequencies of the structure is derived. An analytical solution on beam-induced frequency shift is obtained using a perturbation procedure. It is shown that the frequency shift may be used to measure geometric/physical properties of the beam array. A vibrating crystal plate carrying a beam array may also be considered for application as an ultrasonic brush.     

Effect of couple stress at the interfaces of a nano-hole on the anti-plane electro-mechanical behavior

In piezoelectric nanocomposites, surface/interface plays an important role in determining the size-dependent behavior of media. Within the framework of couple stress, the effect of surface/interface around a nano-hole on the anti-plane electro-mechanical behavior is examined. By introducing a surface/interface model, the stress and electric displacement effects on the size-dependent behavior are both considered. The governing equations in piezoelectric materials are decoupled into the classical ones. The displacement and electric potential are expressed by Bessel functions. By satisfying the boundary conditions around the hole with the interface/surface effect, the expanded coefficients are obtained. Through analysis, it is shown that the mechanical and electrical fields drastically depend on the relative size of the hole with respect to the characteristic length of the material. The effects of couple stresses on the stress and electric field are also addressed. Comparison with the existing results is also given.     

Interaction of a dislocation with an elliptical hole in icosahedral quasicrystals

The interaction between a dislocation and an elliptical hole in icosahedral quasicrystals is considered. An explicit expression for the complex potential is derived using the extended Stroh formalism. Based on the conformal mapping method and a perturbation technique, closed-form solutions are obtained. The field intensity factors at a crack tip and the image forces on the dislocation arising from the crack are calculated. The effects of phonon–phason elastic coupling on the mechanical behavior are also observed.     

Recrystallization in a low-density low-alloy Fe–Mn–Al–C duplex-phase alloy

The recrystallization behaviour of a cold-rolled, low-density, low-alloy duplex-phase alloy (Fe–6.57Al–3.34Mn–0.18C, wt.%) has been studied. Temperature-resolved X-ray diffraction and dilatometry showed that the alloy recrystallizes at 850?°C during continuous heating. However, electron back-scattered diffraction investigations using Kernel average misorientation revealed that during annealing ferrite recrystallizes at lower temperatures while austenite remains strained up to 1200?°C. This study underlines the complexity of recrystallization of a microstructure comprising of constituents with high and low stacking fault energy.     

Perceptual negativity predicts greater reactivity to negative events in daily life

Reinforcement sensitivity theory includes the idea that people differ in their sensitivity to negative events, but relevant process-based assessments have not been developed. The present studies assessed sensitivity to negative events in terms of the extent to which negative word stimuli were perceived to be larger than neutral word stimuli. There was a general tendency to overestimate the size of negative relative to neutral words, but individuals differed substantially in this form of what is termed perceptual negativity. Of more importance, two studies (total N = 151) found systematic relationships between individual differences in perceptual negativity and reactivity to negative events in daily diary protocols. Study 1 found that within-person variations in the occurrence of daily negative events undermined goal-related optimism to a greater extent at higher, relative to lower, levels of perceptual negativity. Study 2 conceptually replicated this interaction in the context of within-person associations between the occurrence of daily negative events and antisocial behavior. These findings are important in advancing reinforcement sensitivity theory, in operationalizing a particular component of it, and in extending it to reactivity processes in daily life.     

Trait emotional intelligence and its links to university performance: An examination

This study aimed at investigating the relationships between academic performance (AP) and cognitive ability, personality traits, and trait emotional intelligence (trait EI or trait emotional self-efficacy) in a sample of 323 (113 female) university students in Cyprus. The study also explored differences across university majors (i.e., computer sciences, business and management, electrical engineering, tourism and marketing, law and accounting, and psychology) in trait EI profiles. Trait EI predicted AP over and above cognitive ability and established personality traits. In addition, there were differences across university majors in trait EI scores; psychology students scored higher on trait EI than computer science, electrical engineering, and business and management students. Implications for studying trait EI in the context of higher education are discussed.     

Adaptive midlife defense mechanisms and late-life health

A growing body of research suggests that personality characteristics relate to physical health; however, this relationship has primarily been tested in cross-sectional studies that have not followed the participants into old age. The present study utilizes data from a 70-year longitudinal study to prospectively examine the relationship between the adaptive defense mechanisms in midlife and objectively assessed physical health in late life. In addition to examining the direct effect, we test whether social support mediates this relationship. The sample consisted of 90 men who were followed for over seven decades beginning in late adolescence. Health ratings from medical records were made at three time points (ages 70, 75, and 80). Defense mechanisms were coded from narratives by trained independent raters (Vaillant, Bond, & Vaillant, 1986). Independent raters assessed social supports between ages 50 and 70. More adaptive defenses in midlife were associated with better physical health at all three time points in late life. These relationships were partially mediated by social support. Findings are consistent with the theory that defense maturity is important for building social relationships, which in turn contribute to better late-life physical health. Psychological interventions aimed at improving these domains may be beneficial for physical health.     

In-Group Favoritism in International Justice Concerns: Power,Involvement, and Attitudes toward the Iraq War and the Cross Straits Relationship in Five Societies

Surveys in the USA, New Zealand, Taiwan, Japan, and China examined attitudes toward the Iraq War and the Cross-Straits Relationship between China and Taiwan. Factor analyses revealed a four-factor solution of justice concerns: (a) national mandate for military intervention, (b) international mandate against military action, (c) procedural justice, and (d) distributive justice issues. Americans and mainland Chinese were significantly different in an in-group favoring direction compared to other societies regarding justice concerns involving their nation. Taiwan, the low-powered society in the Cross-Straits Relationship, was like the uninvolved societies. Justice in international relations is filtered through in-group favoritism for powerful states.