Effect of pre-straining on the size effect in molybdenum pillars

The effect of prior deformation on mechanical behavior as a function of size is investigated for body-centered cubic (bcc) molybdenum (Mo) pillars. Experiments were performed using focused ion beam (FIB) manufactured [0 0 1] and [2 3 5] Mo micro/nanopillars, which were compressed, re-FIB machined, and compressed again. Unlike in bulk materials, pre-straining has a negligible effect on stress–strain behavior of the pillars, suggesting that dislocation storage does not occur in small-scale bcc specimens. The prevailing mechanism behind the size effect is attributed to dislocation nucleation mechanisms.     

Effects of Psychosocial Resources on Elite Soldiers' Completion of a Demanding Military Selection Program

The purpose of this study was to determine the effects of three psychosocial resources (social support, mattering, and self-efficacy), together and separately, on soldiers' completion of a physically challenging military program when controlling for the possible mediating effects of stress. A total of 380 male soldiers entering Special Forces Assessment and Selection Course served as subjects. Results showed that the psychosocial resources were significantly and positively related to the program completion. Expected stress and cognitive stress did not mediate this effect. Of the three psychosocial resources, only the effect of self-efficacy was statistically significant. Implications of the findings are discussed.     

A discrete emotions approach to positive emotion disturbance in depression

Converging findings suggest that depressed individuals exhibit disturbances in positive emotion. No study, however, has ascertained which specific positive emotions are implicated in depression. We report two studies that compare how depressive symptoms relate to distinct positive emotions at both trait and state levels of assessment. In Study 1 (N=185), we examined associations between depressive symptoms and three trait positive emotions (pride, happy, amusement). Study 2 compared experiential and autonomic reactivity to pride, happy, and amusement film stimuli between depressive (n=24; DS) and non-depressive (n=31; NDS) symptom groups. Results indicate that symptoms of depression were most strongly associated with decreased trait pride and decreased positive emotion experience to pride-eliciting films. Discussion focuses on the implications these findings have for understanding emotion deficits in depression as well as for the general study of positive emotion.     

Hooked on a feeling: rumination about positive and negative emotion in inter-episode bipolar disorder

Rumination has been consistently implicated in the onset and maintenance of depression. Less work has examined rumination in the context of bipolar disorder, especially rumination about positive emotion. The present study examined rumination about negative and positive emotion in interepisode bipolar disorder (BD; n = 39) and healthy controls (CTL; n = 34). Trait rumination about positive and negative emotion, as well as experiential and physiological responses to a rumination induction, was measured. Illness course was also assessed for the BD group. Results indicated that the BD group reported greater trait rumination about positive and negative emotion compared with the CTL group, though no group differences emerged during the rumination induction. For the BD group, trait rumination about positive and negative emotion, as well as increased cardiovascular arousal (i.e., heart rate), was associated with greater lifetime depression frequency; trait rumination about positive emotion was associated with greater lifetime mania frequency. These findings suggest that interepisode BD is associated with greater rumination about positive and negative emotion, which in turn is associated with illness course.     

The Psychology of Courage: Modern Research on an Ancient Virtue

While drawing on a limited field of articles and chapters on courage, the editors of The Psychology of Courage: modern research on an ancient virtue have postulated a viable history of the evolution of courage in psychology and chosen a select set of articles which advocate the influence of some of the more modern approaches to psychological thought, while relying only slightly on the historical and alternative views of courage. An alternative view and application of courage presented here examines the impact of courage as a component of a dynamic system. This dynamic systems approach allows for courage to have an interactional impact on the individual regardless of cultural identity or label.     

Human frontal midline theta and its synchronization to gamma during a verbal delayed match to sample task

The involvement of oscillatory activity, especially at theta and gamma frequency, in human working memory has been reported frequently. A salient pattern during working memory is electroencephalographic frontal midline theta activity which has been suggested to reflect monitoring functions in order to deal with a task. In general, theta activity has been credited with integrative functions of distributed activity. In the present study, we focused on electroencephalographic power analyses and cross-frequency phase synchronization in order to test whether frontal midline theta activity is linked to more locally generated gamma oscillations during the performance of a verbal delayed match to sample task. The task consisted of two different conditions where subjects either had to reorganize three consonant letters in alphabetical order (manipulation condition) or where they merely had to retain the three consonant letters (retention condition). Results revealed higher frontal midline theta activity for the manipulation of maintained stimulus material compared to pure retention of stimulus material. Interestingly, power differences between conditions were most pronounced during the second half of the delay period. Cross-frequency phase synchronization between frontal midline theta activity and distributed gamma activity, on the other hand, was predominant during the first half of the delay period and was stronger for manipulation compared to retention. We suggest that coupling of frontal midline theta to gamma activity reflects monitoring functions on the temporal segregation of memory items, whereas higher frontal midline theta power in the second half of the delay period might be associated with rehearsal processes. Rehearsal processes in the manipulation condition are likely more pronounced, because rehearsal of a new letter string in a limited time window requires higher mental effort compared to pure retention where rehearsal processes may already start at the beginning of the delay period.     

Developmental changes of sleep spindles and their impact on sleep‐dependent memory consolidation and general cognitive abilities: A longitudinal approach

Sleep spindles are related to sleep‐dependent memory consolidation and general cognitive abilities. However, they undergo drastic maturational changes during adolescence. Here we used a longitudinal approach (across 7 years) to explore whether developmental changes in sleep spindle density can explain individual differences in sleep‐dependent memory consolidation and general cognitive abilities. Ambulatory polysomnography was recorded during four nights in 34 healthy subjects (24 female) with two nights (baseline and experimental) at initial recording (age range 8–11 years) and two nights at follow‐up recording (age range 14–18 years). For declarative learning, participants encoded word pairs with a subsequent recall before and after sleep. General cognitive abilities were measured by the Wechsler Intelligence Scale. Higher slow (11–13 Hz) than fast (13–15 Hz) spindle density at frontal, central, and parietal sites during initial recordings, followed by a shift to higher fast than slow spindle density at central and parietal sites during follow‐up recordings, suggest that mature spindle topography develops throughout adolescence. Fast spindle density increases from baseline to experimental night were positively related to sleep‐dependent memory consolidation. In addition, we found that the development of fast spindles predicted the improvement in memory consolidation across the two longitudinal measurements, a finding that underlines a crucial role for mature fast spindles for sleep‐dependent memory consolidation. Furthermore, slow spindle changes across adolescence were related to general cognitive abilities, a relationship that could indicate the maturation of frontal networks relevant for efficient cognitive processing. A video abstract of this article can be viewed at: https://www.youtube.com/watch?v=7NXJzm8HbIw and https://www.youtube.com/watch?v=iuMQY1OIJ0s     

Early modulation of visual perception by emotional arousal: Evidence from steady-state visual evoked brain potentials

Allocation of processing resources to emotional picture stimuli was examined using steady-state visual evoked brain potentials (ssVEPs). Participants viewed a set of 60 colored affective pictures from the International Affective Picture System, presented in a flickering mode at 10 Hz in order to elicit ssVEPs. Phase and amplitude of the 10-Hz ssVEP were examined for six picture categories: threat and mutilation (unpleasant), families and erotica (pleasant), and household objects and persons (neutral). Self-reported affective arousal and hedonic valence of the picture stimuli were assessed by means of subjective ratings. Viewing affectively arousing (unpleasant and pleasant) pictures was associated with enhanced ssVEP amplitude at parieto-occipital recording sites, as compared with neutral stimuli. Phase information suggested increased coactivation of right occipitotemporal and frontotemporal sources during processing of affectively arousing stimuli. These findings are consistent with reentrant modulation of early visual processing by distributed networks including subcortical and neocortical structures according to a stimulus's motivational relevance.