青少年领导力发展的研究述评

青少年时期是领导力发展的最佳时机和关键时机。青少年领导力发展是指对青少年所实施的帮助其增强领导力意识、发展领导力素质及掌握领导力技巧的各种经历或活动。本文在回顾国内外青少年领导力发展的模式、途径和内容等相关研究的基础上,提出了青少年领导力发展的未来研究趋势,主要包括：（1）青少年领导力发展理论模式的实证检验;（2）体育课或体育活动中青少年领导力发展的实证探索;（3）中国背景下青少年领导力发展的实证研究。     

情绪对注意范围的影响: 动机程度的调节作用

在匹配了情绪刺激的效价和唤醒度后,检验了情绪的动机程度对注意范围的影响。研究采用Navon字母任务,通过被试对整体字母和局部字母的反应考察了注意范围的变化。结果显示,被试在中性状态下出现整体加工偏向;在低动机程度的正性和负性情绪下偏向加强,注意范围扩大;在高动机程度的正性和负性情绪下偏向减弱,注意范围缩小。因此,在同一效价内动机程度的不同仍会影响注意加工,高动机程度窄化注意范围,低动机程度反之。     

儿童同伴尊重的发展及社交领导性的影响: 三年追踪

对285名小学三年级和四年级儿童进行了连续三年的追踪调查,分析了儿童同伴尊重发展趋势及其在群体间的差异,探讨了社交领导性在儿童同伴尊重发展中的预测作用。结果表明：（1）童年中后期儿童与同伴之间的获得尊重与表现尊重具有显著增长趋势;（2）三年间女孩的表现尊重均高于男孩但增长速度无差异;女孩的获得尊重增长速度高于男孩;（3）儿童的社交领导性能够显著正向预测儿童同伴尊重的发展趋势。     

书法练习对儿童情绪及其调节策略发展的促进作用

本研究采用纵向设计,对170名儿童（实验组：101人;对照组：69人）进行为期两学年的追踪,旨在探讨书法练习对儿童情绪状态及认知性情绪调节策略发展的影响。研究发现,1）以前测成绩为协变量,后测时实验组的积极情绪显著高于对照组;2）实验组在“积极重新关注”、“计划”两维度上的情绪调节策略得分增量（后测-前测）显著高于对照组。结果表明,书法练习对儿童情绪及其调节策略发展具有促进作用。     

Characteristics of Unintentional Movements by a Multijoint Effector

The authors explored the phenomenon of unintentional changes in the equilibrium state of a multijoint effector produced by transient changes in the external force. The subjects performed a position-holding task against a constant force produced by a robot and were instructed not to intervene voluntarily with movements produced by changes in the robot force. The robot produced a smooth force increase leading to a hand movement, followed by a dwell time. Then, the force dropped to its initial value leading to hand movement toward the initial position, but the hand stopped short of the initial position. The undershoot magnitude increased linearly with the peak hand displacement and exponentially with dwell time (time constant of about 1 s). For long dwell times, the hand stopped at about half the total distance to the initial position. The authors interpret the results as consequences of a drift of the referent hand coordinate. Our results provide support for back-coupling between the referent and actual body configurations during multijoint actions and produce the first quantitative analysis of this phenomenon. This mechanism can also explain the phenomena of slacking and force drop after turning visual feedback off during accurate force production task.     

Infiltration behaviour of water in a carbon nanotube under external pressure

The wetting behaviour and associated pressure effect of water in single-walled carbon nanotubes (SWCNTs) are investigated through molecular dynamics (MD) simulations. It is found that water molecules can enter SWCNTs via surface diffusion, and the effective infiltration rate increases with pressure. The effect of pressure on infiltration rate is highly non-linear, exhibiting characteristics of both hydrophilic and hydrophobic surfaces. There exists a nominal infiltration pressure that is dependent on the SWCNT size, above which the water flux is significantly increased.     

Surface tension of substantially undercooled liquid Ti–Al alloy

It is usually difficult to undercool Ti–Al alloys on account of their high reactivity in the liquid state. This results in a serious scarcity of information on their thermophysical properties in the metastable state. Here, we report on the surface tension of a liquid Ti–Al alloy under high undercooling condition. By using the electromagnetic levitation technique, a maximum undercooling of 324 K (0.19 T _L) was achieved for liquid Ti-51 at.% Al alloy. The surface tension of this alloy, which was determined over a broad temperature range 1429–2040 K, increases linearly with the enhancement of undercooling. The experimental value of the surface tension at the liquidus temperature of 1753 K is 1.094 N m^?1 and its temperature coefficient is ?1.422 × 10^?4 N m^?1 K^?1. The viscosity, solute diffusion coefficient and Marangoni number of this liquid Ti–Al alloy are also derived from the measured surface tension.     

Local translational order in the icosahedral quasicrystalline phase of V41Ni36Si23

Abstract

The local translational order of the icosahedral quasicrystalline phase in rapidly solidified V₄₁Ni₃₆Si₂₃ has been investigated by means of selected-area electron diffraction and high-resolution electron microscopy. Experimental results show that translational order always occurs in the twofold direction and can be observed when the quasicrystal is examined along its fivefold and threefold as well as twofold axes. Sometimes it occurs in two or three coplanar twofold directions simultaneously. In these cases some crystalline islands exist in the icosahedral quasicrystal and this corresponds to the initial stage of transformation from a quasicrystal to the stable crystalline phase.