Examining the link between adolescent brain development and risk taking from a social–developmental perspective (reprinted)

The adolescent age period is often characterized as a health paradox because it is a time of extensive increases in physical and mental capabilities, yet overall mortality/morbidity rates increase significantly from childhood to adolescence, often due to preventable causes such as risk taking. Asynchrony in developmental time courses between the affective/approach and cognitive control brain systems, as well as the ongoing maturation of neural connectivity are thought to lead to increased vulnerability for risk taking in adolescence. A critical analysis of the frequency of risk taking behaviors, as well as mortality and morbidity rates across the lifespan, however, challenges the hypothesis that the peak of risk taking occurs in middle adolescence when the asynchrony between the different developmental time courses of the affective/approach and cognitive control systems is the largest. In fact, the highest levels of risk taking behaviors, such as alcohol and drug use, often occur among emerging adults (e.g., university/college students), and highlight the role of the social context in predicting risk taking behavior. Moreover, risk taking is not always unregulated or impulsive. Future research should broaden the scope of risk taking to include risks that are relevant to older adults, such as risky financial investing, gambling, and marital infidelity. In addition, a lifespan perspective, with a focus on how associations between neural systems and behavior are moderated by context and trait-level characteristics, and which includes diverse samples (e.g., divorced individuals), will help to address some important limitations in the adolescent brain development and risk taking literature.     

教育神经科学:探究人类认知与学习的一条整合式途径

教育神经科学是第二代认知科学对人的具身认知进行认识深化的必然产物,也是不同层面研究以整合态势来研究教育情境中人的认知过程及其发展的当然结果。在认知神经科学与教育已有的良好沟通下,教育神经科学就是要通过教育学家、心理学家、神经科学家等的合力,借助多种技术(包括脑成像技术),多视角、多层面地分析人的心理活动,以求最终达到科学改进教育理论及其做法的目的。不可否认,本研究领域还存在一些问题;但这并不会就此阻止教育学、心理学、神经科学加快合作与融合的步伐。     

Nature's Longing for Beauty: Elegance as an Evolutionary Attractor,with Implications for Human Systems

This article suggests that the tendency of living systems to move toward more practical and more aesthetically fitting states be hypothesized as an evolutionary principle. The viewpoints of scientists and systems thinkers on the place of elegance in nature are considered, along with a discussion of issues related to perception of beauty. Implications for human systems and for meeting the challenges we presently face are considered.     

Personal and impersonal stimuli differentially engage brain networks during moral reasoning

Moral decision making has recently attracted considerable attention as a core feature of all human endeavors. Previous functional magnetic resonance imaging studies about moral judgment have identified brain areas associated with cognitive or emotional engagement. Here, we applied graph theory-based network analysis of event-related potentials during moral decision making to reveal the personal/impersonal distinction in the organization of functional connectivity. Our results indicated that the personal task had more larger long-range connections involved in frontal regions and the right hemisphere, and higher network efficiency of some frontal electrodes such as F2 than the impersonal. These might be related to brain resource reorganization contributing to efficient conflict resolution. These findings provide new insights into neural mechanisms of moral dilemmas.     

Characterization of Al/n-ZnO/p-Si/Al structure with low-cost solution-grown ZnO layer

We report the fabrication of Al/n-ZnO/p-Si/Al diode structures with a flower-like ZnO layer. The average grain size, microstrain and dislocation density in the ZnO layer were determined as 25?nm, 1.55?×?10^?3 and 3.23?×?10¹³?cm^?2, respectively. From absorption spectra, the optical band gap was found to be ～3.17?eV. A red shift was attributed to non-stoichiometry arising from Zn⁺² ions substituting for oxygen vacancies. The ideality factor was determined as 1.55. The barrier height was calculated as 0.71?eV from I–V characteristics and 0.73?eV using the Norde plots.     

Interfacial defects in YBa2Cu3O7-δ/SrTiO3(0 0 1) heterostructures studied by aberration-corrected ultrahigh-resolution electron microscopy

The microstructure of interfacial defects in YBa₂Cu₃O_7-δ/SrTiO₃(0?0?1) heterostructures has been investigated by aberration-corrected ultrahigh-resolution electron microscopy. We determine that c-axis-oriented YBa₂Cu₃O_7-δ thin films epitaxially grow on SrTiO₃(0?0?1) with two types of interface structure. The coalescence of nucleation sites with different types of interface structure leads to the formation of antiphase domain boundaries in YBa₂Cu₃O_7-δ thin films, which terminate at planar faults with different configurations near the interface. Stand-off misfit dislocations are observed and the dislocation core structure is explored. Based on the interface structure and interfacial defects, the initial growth mode of YBa₂Cu₃O_7-δ thin films on SrTiO₃(0?0?1) is discussed.     

Commensurate-incommensurate phase transition in muthmannite,AuAgTe2: first evidence of a modulated structure at low temperature

To study the temperature-dependent structural changes and to analyze the crystal chemical behavior of silver as a function of temperature, a crystal of muthmannite, AuAgTe₂, has been investigated by X-ray single-crystal diffraction methods at 300 K and 110 K. At room temperature, muthmannite was confirmed as belonging to the space group P2/m, while at low temperature (110 K) it undergoes a reversible commensurate–incommensurate phase transition with a modulation wave vector q = 0.215(1)a* + 0.379(2)c*. Muthmannite reconverts to the commensurate type upon returning to room temperature, thus indicating that the phase transition is completely reversible in character. The average structure of the low-temperature muthmannite remains monoclinic, space group P2/m, and shows only normal thermal compression over the entire temperature range investigated. Crystal-chemical characteristics are compared with published data on the other members of the system Au–Ag–Te. Speculations on the possible origin of the modulated structure at low temperature are also given.     

A criterion for determining the optimum value of twist in the topological model

In previous works, in which the topological model has been applied to martensitic phase transformations, the value of twist angle ω was determined based on the habit plane-(HP) matching method, where the physical realization of the so-predicted interfacial defect networks may require reorientations of defect line directions by short-range diffusion, though no long-range diffusion was needed. In the present work, a novel criterion for determining the optimum value of twist is proposed so that the predicted interface defects are not only able to fulfil the function of fully accommodating the coherency strains arising on the terrace plane, but also capable of reaching the required position at the HP without long- or short-range diffusions. A numerical analysis for an Fe–20Ni–5Mn alloy is demonstrated based on the newly proposed criterion, and the predictions so obtained are in good agreement with the results provided by the phenomenological theory and experimental measurements.     

Mobility of c dislocations in Ti3, Al

Abstract

The rôle of dislocations with Burgers vectors, b, given by b = [0001] during deformation of samples of the intermetallic compound Ti₃Al has been assessed. At room temperature, the experimental evidence is consistent with these dislocations being sessile, their density and morphology being similar to that in undeformed samples. In samples deformed at 650°C and above, it is concluded that motion of these dislocations is effected by dislocation climb. The line directions of the various segments of dislocations with b= [0001] are shown to be perpendicular to planes that contain sheets of Ti atoms, with an expected tendency to exhibit a high Peierls stress.