Relaxation of electrons following trapping in the space-charge-limited conduction regime of n + -i-n + hydrogenated amorphous silicon structures

The relaxation of a space charge due to trapped electrons in an n + -i-n + hydrogenated amorphous silicon structure has been modelled by Solomon. Here we extend the model by obtaining analytical expressions for the current at the beginning of the relaxation as well as for long times when retrapping of electrons is taken into account. Our expression for the current at long times differs considerably from that given previously. Consequences for the derived values of the capture cross-sections of the gap states near the Fermi level are examined and discussed.     

Equivalent strain-hardening work theorem

A new physical concept, termed ‘equivalent strain-hardening work’, is proposed. The physical concept can be used to redefine the commonly used effective stress and effective strain theory as applied in constructing the constitutive relations of stress and strain, especially when related to an anisotropic strain-hardening material. The concept concerns that part of plastic work which emphasizes the action due to the strain-hardening behaviour of a material. Based on this concept, any one of the strain-hardening stress–strain curves obtained through common experiments on anisotropic materials can be selected as a nominally effective stress and an associated effective strain, and the rest of the strain-hardening relations can all be then transformed to be functions of variables of the nominally effective strain. Thus, any kind of loading path can be characterized by a single relation between effective stress and effective strain. When applied to the isotropic materials, the equivalent strain-hardening work concept is identical with the work-equivalent deformation concept but is more general.     

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.     

Determination of Peierls stress from acoustic harmonic generation

The interaction of acoustic waves with dislocations leads to aperiodic oscillations in the magnitude of the acoustic nonlinearity parameter β as a function of the acoustic drive amplitude σ _ampl. The magnitude and spacing of the oscillations depend on the value of the Peierls stress. A least-square curve fit of the β(σ _ampl) equation to experimental data taken of 99.999% pure aluminum monocrystals oriented for wave propagation along the [1?0?0] crystal axis yields the value 6.2?×?10⁴?Pa for the Peierls stress. The value is consistent with the smallest values reported in the literature for aluminum where for both theoretical and experimental studies the reported values range over three orders of magnitude.     

High-speed photography of low-velocity impact cracking of solid spheres

Results from a high-speed photographic study of low-velocity impact cracking of optically transparent acrylic resin and poly(methyl methacrylate) spheres of 12.7mm diameter are described. It is shown that, in a sphere undergoing an impact, cracking occurs after the sphere has been plastically deformed. The point of initiation of cracking is shown to be located at the circle of contact between the sphere and the impacting platen. The cracking then develops throughout the sphere, with cracks attaining velocities of 600-800ms^-1. It has been suggested that crack initiation at the contact circle is caused by the tensile circumferential stress, which is generated owing to the plastic flow of the sphere.     

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.     

Emotional Processing Therapy for post traumatic stress disorder

While prolonged exposure is considered one of the “gold standard” and recommended treatments for post traumatic stress disorder (PTSD), it has been poorly utilised in clinical practice. Individuals with PTSD often find it too distressing to confront memories, and therapists may be uncomfortable using the therapy. A new Emotional Processing Therapy is described in which an emotional approach to prolonged exposure provides individuals with a new insight into how trauma is processed. A conceptual analysis of exposure suggests that it is exposure to distressing emotional experiences which is a key element. Viewing it as an emotion-based therapy, allows the creative addition of new emotional elements. Through exploring the individual’s emotional processing style, previously learned and unhelpful patterns can be addressed, and the addition of an “emotional preparation” phase helps them understand why it is important to face emotionally distressing memories before exposure sessions begin. Emotional Processing Therapy is intuitive and makes sense to those affected by PTSD. It is framed in an emotional context and is presented as part of a lifestyle change that may reduce the likelihood of psychological problems developing in the future.     

Understanding the role of social support in trajectories of mental health symptoms for immigrant adolescents

This longitudinal study of 286, urban residing, first- and second-generation immigrant adolescents examined the degree to which acculturative stress is related to the developmental trajectories of mental health problems and the role of social support in this process. Participants were recruited when they entered 10th grade and two additional waves of data were gathered at 12-month intervals. Using individual growth curve modeling, the results show significant decline in internalizing mental health problems during the high school years. At the same time, greater exposure to acculturative stress predicted significantly more withdrawn/depressed, somatic, and anxious/depressed symptoms. Additionally, social support moderated the relation between acculturative stress and anxious/depressed symptoms. Gender and generation status differences were found only at baseline (10th grade).     

Differential effects of the different Short Self-Applied Relaxation Therapy (SART) components on anxiety,activation and stress / Efectos diferenciales de los distintos componentes de la Relajación Breve Sugestiva Auto aplicada (RBSA) sobre la ansiedad,la activación y el estrés

Abstract

Relaxation techniques have evidence-based support in the research community. However, not all relaxation techniques have the same effectiveness or generate the same states of relaxation. For this reason, indications should be established for each of them. Studies into Self-Applied Relaxation Therapy (SART) show that they can decrease anxiety, stress, blood pressure and craving. This study explores to what extent each SART component is responsible for the results found, which is the most appropriate depending on the target variable to be controlled and whether any of the components are dispensable. Ninety-three university volunteer students participated in the study, aged between 18 and 45; 81.70% were female. Results showed that each of the components had similar efficacy and paradoxical effects on certain participants (8% to 26%). From a clinical perspective, this study concludes that SART can be adapted to the user, and a specific combination of components should be designed for each patient.     

A Novel “Planetary Man”: From the Philosophical Paradigm of Modernity to Contemporary Anthropological Mutation: The Perspective of Ernesto Balducci

Italian priest, essayist, and intellectual of the twentieth century, Ernesto Balducci identified the crucial turning points of the new millennium by advancing original perspectives capable of opening unusual future scenarios. Sensitive to emergences of society (pollution, wars, ecological collapse), he retraces the causes in the more general “crisis of modernity,” proposing a new paideia and a new model of thought. He theorizes the construction of a novel planetary horizon that presupposes not only the building of new organizational structures, but also the achieving of an authentic “anthropological mutation” capable of inverting the course of history. While the old ethics were anthropocentric, founded on the supremacy of humankind over the world and nature, the new ethics is planetary, meaning that humankind must no longer be used as the parameter, but instead, the global horizon over which the effects of his or her actions extend.