Importance of chamber gas pressure on processing of Al-based metallic glasses during melt spinning

The effect of chamber gas pressure on the amorphicity of Al₈₅Ni₅Y₁₀ alloy was studied for the melt-spinning process. The amorphicity of as-quenched ribbons was characterized by X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The chamber atmosphere pressure is crucial to the cooling rate of melt spinning. At high vacuum, at pressure less than 0.001?atm, fully crystalline fragments are obtained. Monolithic amorphous ribbons were only obtained at a gas pressure of 0.1?atm, 0.2?atm or higher. The extended contact length between ribbons and the copper wheel contributes to the high cooling rate of melt spinning in Al-based glass forming alloys; that is supported by images recorded by a high-speed camera. Higher chamber pressure increases contact length between ribbons and the wheel, which is qualitatively elucidated by Bernoulli's equation.     

Memory for Movement in Blind Children

The author assessed the mechanisms underlying skilled production of keying sequences in the discrete sequence-production task by examining the effect of sequence length on mean element execution rate (i.e., the rate effect). To that end, participants (N = 9) practiced fixed movement sequences consisting of 2, 4, and 6 key presses for a total of 588 trials per sequence. In the subsequent test phase, the sequences were executed with and without a verbal short-term memory task in both simple and choice reaction time (RT) paradigms. The rate effect was obtained in the discrete sequence-production task—including the typical quadratic increase in sequence execution time (SET, which excludes RT) with sequence length. The rate effect resulted primarily from 6-key sequences that included 1 or 2 relatively slow elements at individually different serial positions. Slowing of the depression of the 2nd response key (R₂) in the 2-key sequence reduced the rate effect in the memory task condition, and faster execution of the 1st few elements in each sequence amplified the rate effect in simple RT. Last, the time to respond to random cues increased with position, suggesting that the mechanisms that underlie the rate effect in new sequences and in familiar sequences are different. The data were in line with the notion that coding of longer keying sequences involves motor chunks for the individual sequence segments and information on how those motor chunks are to be concatenated.     

To watch or not to watch: Infants and toddlers in a brave new electronic world

For some time now, questions have been asked about the impact of television and video materials on the cognitive and social development of preschoolers and older children. More recently, these same questions have been asked in relation to the extensive exposure to these media that infants and toddlers are currently experiencing. To answer these questions, we review current research that explicitly targets these concerns and provide new insights into the role these media play in early development.     

Influence of the role of a partner on anxiety due to a physically threatening situation

This study aimed to examine the influence of the presence of a partner in terms of affiliation level and role on anxiety in a physically threatening situation.

In the first experiment, nine male subjects waited alone for the electric shock, and the other nine subjects waited with their partner.

In the second experiment, 36 female subjects were assigned to four experimental groups by the difference of the role of a partner (coactor or audience) and the affiliation level of a partner (friend or stranger), and subjects waited for the electric shock with their partner.

It was found that anxiety of subjects decreased when the partner was a coactor and/or a friend. It was suggested that these two functioned differently in anxiety reduction in a physically threatening situation.     

Vagal influence during worry and cognitive challenge

Abstract

The primary foci of the study were exploration of the linkage between cognitive and autonomic inflexibility of worry and generalized anxiety disorder (GAD) and examination of the effects of an analog cognitive restructuring task on this relationship. Cardiac responses of GAD and non-GAD participants were measured to examine the sympathetic and parasympathetic effects of worry and cognitive challenge. Diagnostic groups of undergraduate students were determined via administration of a structured interview, yielding a GAD group (n=16) and a control group (n=19) of individuals without GAD, depression, or panic disorder diagnoses. Cardiac autonomic responses were acquired via electrocardiogram during rest, worry, and cognitive challenge conditions by an experimenter blind to diagnosis. Metrics were compared between the two groups and across the three conditions. Individuals diagnosed with GAD did not differ significantly from controls on autonomic indices. Worry was associated with significantly decreased parasympathetic influence and increased sympathetic activity. Cognitive challenge did not result in significant increased cardiac responsivity. The results indicate that worry behavior is associated with decreased vagal activity, suggest a linkage between autonomic and cognitive inflexibility, and provide further suggestions for improving protocols to assess the autonomic effects of cognitive therapy techniques.     

Psychophysiological Reactivity to Abuse-Related Stimuli in Sexually Revictimized Women

Prior research shows discrepant findings in relation to psychophysiological reactivity to threat in women with histories of sexual victimization. Women ages 18 to 22 (N?=?123) with histories of sexual abuse were categorized into child sexual abuse (CSA), adult sexual victimization, revictimization, or nonvictimization groups. Low- and high-frequency heart rate variability were measured at baseline and during an Emotional Stroop task of abuse-related words. Revictimized women showed a significant decrease from baseline to task in both parasympathetic and sympathetic measures when compared to the CSA group. The CSA group demonstrated chronic sympathetic activation at both baseline and task, relative to the revictimization group. Groups did not differ on performance (i.e., reaction time) on the Emotional Stroop task (i.e., more threatening stimuli, slower performance). Cardiovascular responses reported might point to biological reactivity patterns needed for women with a history of sexual abuse to cope with abuse-related stimuli.     

Kinetic analysis of oxygen dynamics under a variable work rate

Measurements of oxygen uptake are central to methods for the assessment of physical fitness and endurance capabilities in athletes. Two important parameters extracted from such data of incremental exercise tests are the maximal oxygen uptake and the critical power. A commonly accepted model of the dynamics of oxygen uptake during exercise at a constant work rate comprises a constant baseline oxygen uptake, an exponential fast component, and another exponential slow component for heavy and severe work rates. We have generalized this model to variable load protocols with differential equations that naturally correspond to the standard model for a constant work rate. This provides the means for predicting the oxygen uptake response to variable load profiles including phases of recovery. The model parameters have been fitted for individual subjects from a cycle ergometer test, including the maximal oxygen uptake and critical power. The model predictions have been validated by data collected in separate tests. Our findings indicate that the oxygen kinetics for a variable exercise load can be predicted using the generalized mathematical standard model. Such models can be applied in the field where the constant work rate assumption generally is not valid.     

Responses to false physiological feedback in individuals with panic attacks and elevated anxiety sensitivity

Participants with elevated anxiety sensitivity and a history of panic attacks were compared to a low anxiety comparison group with respect to physiological and subjective reactivity to false heart-rate feedback and reactivity to a priming procedure. Whereas accurate heart-rate feedback elicited minimal responses, participants across groups showed significant physiological and subjective responses to false feedback. High risk and low risk participants did not differ in heart-rate responses to false feedback, though panic attack frequency did predict physiological and subjective reactions to false feedback in the high risk group. Self-reported nonspecific anxiety was significantly higher in high risk female participants than in low risk female participants, while males did not different in general subjective anxiety. However, high risk participants reported more panic-specific symptoms during the false feedback task than low risk participants, regardless of the sex of the participant. Therefore, although the experimental paradigm appeared to trigger nonspecific anxiety in high risk female participants, panic attack symptoms in reaction to the task were specific to risk group, not sex, and consistent with hypotheses. Surprisingly, the priming procedure did not influence physiological or subjective responses to false feedback in either group. These results raise additional questions regarding the process and impact of interoception in individuals with panic attacks, and suggest that false perception of internal changes may contribute to risk for panic disorder when exposed to believable cues.     

结合a分层的兼具项目曝光和广义测验重叠率控制的选题策略

测验安全和题库使用率在计算机化自适应测验中十分重要, 特别是高风险测验。传统的SHGT法兼具同时控制项目曝光率和广义测验重叠率的功能, 但题库使用率较差。a分层法能够提高题库使用率, 但对过度曝光的项目控制不足。本研究将a分层法的思想与SHGT法相结合, 各取所长, 提出了3种新的选题方法：SHGT_a法, SHGT_b法和SHGT_c法。研究结果表明：(1)与SHGT法相比, 新方法均可以在有效地控制项目曝光率和广义测验重叠率同时, 极大地提高题库使用率; (2)随着预设项目曝光率(rmax)和广义测验重叠率( )取值的增大以及共享人数a的减小, 新方法对被试能力估计的精度呈上升趋势。比起SHGT法, 新方法仍能保持很高的题库使用率; (3)当区分度和难度的相关(rab)较大时, SHGT_b和SHGT_c法在能力估计精度方面优于SHGT_a法; (4)在不同的测验考察内容比例下, 3种新方法对被试能力估计的精度均较好; (5)与SHGT法相比, 新方法能够有效地控制项目曝光率过度控制的问题。