Tunable wave-vector filtering in a two-dimensional electron gas modulated by magnetic barriers and δ-doping

We report a theoretical investigation on the control of wave-vector filtering (WVF) in a two-dimensional electron gas modulated by realistic magnetic barriers and δ-doping, which can be experimentally realised by depositing a ferromagnetic stripe on the surface of a GaAs/Al_xGa_1?xAs heterostructure and using atomic layer doping. Theoretical analysis demonstrates that a sizeable WVF effect still exists even if δ-doping is introduced into the device. Numerical calculation reveals that the WVF efficiency is related closely to the δ-doping. Thus, the WVF effect in a magnetic nanostructure can be conveniently manipulated by properly adjusting the weight and/or the position of the δ-doping, giving rise to a tunable momentum filter for nanoelectronics applications.     

In situ stress relaxation mechanism of a superelastic NiTi shape memory alloy under hydrogen charging

On account of its good biocompatibility, superelastic Ni–Ti arc wire alloys have been successfully used in orthodontic clinics. Nevertheless, delayed fracture in the oral cavity caused by hydrogen diffusion can be observed. The in situ stress relaxation susceptibility of a Ni–Ti shape memory alloy towards hydrogen embrittlement has been examined with respect to the current densities and imposed deformations. Orthodontic wires have been relaxed at different martensite volume fractions using current densities of 5, 10 and 20 A/m² at 20 °C. The in situ relaxation stress shows that, for an imposed strain at the middle of the austenite–martensite transformation, the specimen fractures at the martensite–austenite reverse transformation. However, for an imposed strain at the beginning of the austenite–martensite plateau, the stress decreases in a similar way to the full austenite structure. Moreover, the stress plateau has been recorded at the reverse transformation for a short period. For the fully martensite structure, embrittlement occurs at a higher stress value. This behaviour is attributed to the interaction between the in situ austenite phase expansion and the diffusion of hydrogen in the different volume fractions of the martensite phase, produced at an imposed strain.     

Cardiovascular reactions to psychological stress and abuse history: the role of occurrence,frequency, and type of abuse

Background and objectives: Extreme cardiovascular reactions to psychological stress have been associated with traumatic life experiences. Previous studies have focused on the occurrence or frequency of abuse rather than type of abuse. We examined how occurrence, frequency, and the type of abuse history are related to cardiovascular reactivity (CVR) to acute psychological stress. Design: The study consisted of between group and continuous analyses to examine the association between occurrence, type, and frequency of abuse with cardiovascular reactions to acute psychological stress. Methods: Data from 64 participants were collected. Heart rate, systolic blood pressure, and diastolic blood pressure were measured at baseline and during a standard mental arithmetic stress task. Results: Individuals who experienced abuse showed diminished CVR to acute psychological stress; this was driven specifically by the history of sexual abuse. Frequency of abuse did not relate to stress reactions. Conclusions: These findings accord with previous work suggesting a relationship between traumatic life experience and hypoarousal in physiological reactivity and extend previous findings by suggesting the relationship may be driven by sexual abuse.     

Group‐analytic network process for balancing stakeholder views on fire protection of steel‐framed buildings

To select appropriate fire protection options for buildings during their design stage, economic, safety, environmental, and societal criteria need to be accounted for. The divergent and sometimes conflictual desires from different fire design stakeholders involved in the process present a multicriteria decision problem. Design decision criteria and fire protection options can be interdependent, and so there is a need to manage these desires with an advanced decision analysis technique, thereby reducing uncertainties in the complex decision‐making process. The aim of this paper is to use the weighted/geometric mean method‐analytic network process (W/GMM‐ANP) to balance the opinions of fire design stakeholders extracted from 42 structured stakeholder interviews on selecting the most suitable fire protection option for buildings constructed of steel frames. Different categories of interdependent decision elements were developed from 22 design decision criteria and 5 proposed fire protection options to produce a network of decision clusters for multicriteria decision analysis. In the synthesis and ranking of fire protection options, the W/GMM‐ANP accounted for the multiple interdependencies of weighted and unweighted stakeholder desires and managed the complexity of the decision‐making problem. The technique is proposed for approaching suitable group decisions in structural fire design of steel‐framed buildings as well as other performance‐based engineering decision making that may involve multidisciplinary stakeholders.     

认知分心的强度对创伤性信息加工的影响

结合ERP技术、创伤电影范式和改进的工作记忆范式探讨了认知分心的强度对创伤性信息加工的影响。结果发现, (1)高负荷上的N2波幅显著大于低负荷上的。(2)在低工作记忆负荷上, 创伤负性图引发的LPP波幅显著大于创伤中性图和无关中性图; 而在高工作记忆负荷上, 三类图片引发的LPP波之间差异不再显著。(3)在创伤负性图上高、低负荷工作记忆任务诱发的LPP波差异显著, 且高负荷条件下的LPP波幅显著小于低负荷条件。结果表明, 相比低认知控制, 早期高认知控制对创伤性信息的调节更有效, 支持了认知控制理论。     

概化理论缺失数据方差分量估计

各种心理调查、心理实验中, 数据的缺失随处可见。由于数据缺失, 给概化理论分析非平衡数据的方差分量带来一系列问题。基于概化理论框架下, 运用Matlab 7.0软件, 自编程序模拟产生随机双面交叉设计p×i×r缺失数据, 比较和探讨公式法、REML法、拆分法和MCMC法在估计各个方差分量上的性能优劣。结果表明：(1) MCMC方法估计随机双面交叉设计p×i×r缺失数据方差分量, 较其它3种方法表现出更强的优势; (2) 题目和评分者是缺失数据方差分量估计重要的影响因素。     

注视方向和面部表情对注意朝向的影响

摘 要 本文以三种表情面孔为材料,运用事件相关电位（ERP）方法探讨表情线索在注意朝向中与注视转移发生的交互及两者如何共同影响观察者的反应。结果发现：（1）线索效应在三种表情面孔的两种SOA中都出现了;（2）SOA较长时,注视线索效应量间的显著差异出现在中性和恐惧面孔、高兴和恐惧面孔间;（3）面部表情的效应出现在了表情线索诱发的P1成分上;（4）目标诱发的P1和N1说明了注视线索效应的存在及与表情间的交互。结论：表情线索先对观察者的朝向反应产生影响,随后是注视线索及其与表情线索发生的交互。     

内隐自尊的特性：来自EAST的证据

采用外部情绪性Simon任务（EAST）对109名大学生对代表自我和他人的刺激词的态度差异进行测量,从而探讨内隐自尊的特性。结果显示：在个体的认知图式中,对自我持有一种内隐的积极的评价或态度,对他人持有一种内隐的相对消极的评价或态度。具体表现在：（1）内隐自尊的特性是将自己与积极的评价和情感相联系,将他人与消极的评价和情感相联系;（2）自我姓名激活的积极的内隐自我态度比一般性自我词更为强烈,而他人姓名激活的消极的内隐态度比一般性非我词更弱。本研究表明,EAST能有效检测出内隐自尊效应,并可以同时获得个体对自我和他人的内隐态度的强度和方向,为内隐自尊研究提供了一种新的有效的方法,但其应用仍需谨慎。     

Tag, you're it: Tagging as an alternative to yes/no recognition in item method directed forgetting

The current study contrasted a standard yes/no recognition task with a tagging recognition task in the context of an item-method directed forgetting paradigm. During the study phase, a series of words was presented one at a time, each followed by an instruction to remember (R) or forget (F). The retention of R and F study words was tested using either a typical yes/no recognition task or a tagging recognition task in which participants labeled each word as “R”, “F” or “New”. The directed forgetting effect observed in each task was equivalent in magnitude. However, the tagging recognition task afforded an additional analysis of the errors of misattribution that was not possible with the more typical yes/no recognition task. Interestingly, when falsely recognizing a Foil word, participants were more likely to assign an “F” tag than an “R” tag. These errors of misattribution are consistent with existing accounts of directed forgetting that suggest R words are better encoded than F words. We argue for the utility of the tagging procedure, given it does not alter the directed forgetting effect normally seen with yes/no recognition but provides additional information about errors of misattribution.     

An Analogue Study of the Psychological and Psychosocial Processes Associated With Post‐concussion Symptoms

This study used an analogue design to investigate post‐concussion syndrome and the psychological and psychosocial processes associated with post‐concussion symptom (PCSx) reporting. The study examined the role of expectation in reporting of PCSx, the nature of associated psychological and psychosocial difficulties, and the “good‐old‐days” phenomenon. Forty‐five healthy participants were randomly assigned to one of two groups: (1) a control group or (2) an expectation group who were asked to perform as if they had experienced a mild traumatic brain injury. Fourteen psychiatric patients comprised the clinical group. Self‐report questionnaires assessing PCSx and psychological and psychosocial variables were administered. It was hypothesised that PCSx would be non‐specific, that the expectation group would report greater dysfunction than controls, and that the “good‐old‐days” phenomenon would cause the expectation and clinical groups to underestimate pre‐morbid PCSx. All participants reported some degree of dysfunction, and the expectation and clinical groups underestimated past PCSx. The expectation group reported more PCSx and psychological and psychosocial dysfunction than controls, resembling the clinical group. The results demonstrate that expectation can cause otherwise healthy individuals to resemble a clinical group in terms of their level of endorsement of psychological and psychosocial dysfunction.