Micro- vs. macro-phase separation in binary blends of poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide) diblock copolymers

In this paper we present an experimentally determined phase diagram of binary blends of the diblock copolymers poly(styrene)-poly(isoprene) and poly(isoprene)-poly(ethylene oxide). At high temperatures, the blends form an isotropic mixture. Upon lowering the temperature, the blend macro-phase separates before micro-phase separation occurs. The observed phase diagram is compared to theoretical predictions based on experimental parameters. In the low-temperature phase the crystallisation of the poly(ethylene oxide) block influences the spacing of the ordered phase

Longitudinal changes in functional connectivity of cortico-basal ganglia networks in manifests and premanifest huntington's disease

Huntington's disease (HD) is a genetic neurological disorder resulting in cognitive and motor impairments. We evaluated the longitudinal changes of functional connectivity in sensorimotor, associative and limbic cortico-basal ganglia networks. We acquired structural MRI and resting-state fMRI in three visits one year apart, in 18 adult HD patients, 24 asymptomatic mutation carriers (preHD) and 18 gender- and age-matched healthy volunteers from the TRACK-HD study. We inferred topological changes in functional connectivity between 182 regions within cortico-basal ganglia networks using graph theory measures. We found significant differences for global graph theory measures in HD but not in preHD. The average shortest path length (L) decreased, which indicated a change toward the random network topology. HD patients also demonstrated increases in degree k, reduced betweeness centrality bc and reduced clustering C. Changes predominated in the sensorimotor network for bc and C and were observed in all circuits for k. Hubs were reduced in preHD and no longer detectable in HD in the sensorimotor and associative networks. Changes in graph theory metrics (L, k, C and bc) correlated with four clinical and cognitive measures (symbol digit modalities test, Stroop, Burden and UHDRS). There were no changes in graph theory metrics across sessions, which suggests that these measures are not reliable biomarkers of longitudinal changes in HD. preHD is characterized by progressive decreasing hub organization, and these changes aggravate in HD patients with changes in local metrics. HD is characterized by progressive changes in global network interconnectivity, whose network topology becomes more random over time. Hum Brain Mapp, 2016. © 2016 Wiley Periodicals, Inc

Association Between Anxiety, Depression, and Post-traumatic Stress Disorder and Outcomes After Ischemic Stroke

Background: Stroke patients are known to be at risk of developing anxiety, depression, and post-traumatic stress disorder (PTSD).Objective: To determine the overlap between anxiety, depression, and PTSD in patients after stroke and to determine the association between these disorders and quality of life, functional status, healthcare utilization, and return to work.Methods: A cross-sectional telephone survey was conducted to assess for depression, anxiety, PTSD, and health-related outcomes 6–12 months after first ischemic stroke in patients without prior psychiatric disease at a single stroke center.Results: Of 352 eligible subjects, 55 (16%) completed surveys. Seven subjects (13%) met criteria for probable anxiety, 6 (11%) for PTSD, and 11 for depression (20%). Of the 13 subjects (24%) who met criteria for any of these disorders, 6 (46%) met criteria for more than one, and 5 (39%) met criteria for all three. There were no significant differences in baseline characteristics, including stroke severity or neurologic symptoms, between those with or without any of these disorders. Those who had any of these disorders were less likely to be independent in their activities of daily living (ADLs) (54 vs. 95%, p < 0.001) and reported significantly worse quality of life (score of 0–100, median score of 50 vs. 80, p < 0.001) compared to those with none of these disorders.Conclusions: Anxiety, depression, and PTSD are common after stroke, have a high degree of co-occurrence, and are associated with worse outcomes, including quality of life and functional status

Motivation gains in performance groups: Paradigmatic and theoretical developments on the Köhler effect.

In contrast to many demonstrations of social loafing, relatively few studies have documented group motivation gains. One such exception was 0. Köhler's (1926, 1927) finding that team members working together did better at a taxing persistence task than would be expected from their individual performances, particularly when there was a moderate discrepancy in coworkers' capabilities. In Experiment 1, we developed a paradigm within which Köhler's overall motivation gain effect could be replicated, although the discrepancy in coworkers' capabilities did not moderate these motivation gains (after statistical artifacts were taken into account). Experiment 2 indicated that this motivation gain occurred under conjunctive but not under additive task demands, suggesting that the instrumentality of one's contribution to valued outcomes is a more likely explanation of the Köhler effect than social comparison processes

Revisiting the Koehler effect: Does diversity enhance motivation and performance in groups.

Based on systematic experimental research, we explore in this chapter whether increases in group performance might be a function of diversity in group members‘ capabilities, and how aspects of this group diversity can be used to produce "synergy" in teams. After a short review of experimental research on motivation gains in groups, we particularly focus on the "Köhler effect" that (a) demonstrated conditions under which group members were motivated to exert more efforts for their group than under individual working conditions, and (b) suggested that these motivation gains only occurred when coworkers differed moderately in their abilities. After discussing results of Köhler’s original work (1926, 1927) and possible explanations, we describe two recent studies that replicated essential features of Köhler’s paradigm in a more controlled setting. Results demonstrated reliable performance gains in groups only under conjunctive task conditions, suggesting that perceived instrumentality of own contribution for the group outcome is an important factor to understand synergetic processes. However, no moderation of these performance gains by group diversity was found, demonstrating that these effects can be more general than Köhler (1926, 1927) assumed. The implications of these results for applied questions are discussed

Belief discrepant behavior and the bogus pipeline.Impression management or arousal attribution.

Based on recent studies impression management theorists conclude that following belief discrepant behavior, persons will feign attitude change on paper measures, but report their “true” beliefs when attached to a lie detector (the bogus pipeline). A dissonance arousal explanation of these bogus pipeline results suggests that subjects may attribute their arousal to the bogus pipeline equipment instead of to dissonance and therefore may not be motivated to change their attitudes. The present study examined these competing interpretations and yielded results which support the dissonance arousal attribution explanation. Subjects who were attached to a (bogus pipeline) lie detector exhibited attitude change if given the opportunity to get accustomed to the equipment (which made attribution of arousal to the equipment less plausible), but showed no attitude change if no habituation experience was provided

The Role of Competitiveness at Social Tasks: Can Indirect Cues Enhance Performance?

Recent research has shown that competitiveness is related to performance. However, gaps remain in the literature on the effects of competitiveness on task performance across different performance settings. A review of relevant literature from sport, social, and personality psychology suggested that performance in several contexts—individual, coactive, and conjunctive task demands—would be affected both by trait interpersonal competitiveness and by competitiveness manipulated through subliminal priming. Both factors (task demands and competitiveness) were manipulated in a 2 × 3 experimental design and individual task effort was assessed. Results from the current investigation showed that such priming influenced effort at a coactive persistence task. Results also partially replicated past research on group motivation gains (Hertel, Kerr, & Messé, 1999; Köhler, 1926, 1927). Implications for group and individual performance in social, athletic, and work domains are discussed

Trying Harder for Different Reasons

Past investigations of performance on a conjunctive physical persistence task have yielded consistent evidence of motivation gains in the less able worker - a pattern first seen in data collected over 70 years ago (Köhler, 1926, 1927). Moreover, recent work indicates that these gains are due to the increased instrumentality of the weaker participant's efforts. The present study sought to demonstrate that another potential factor in the work context - the sex composition of the group, which is known to moderate self-presentation concerns - could also affect such motivation gains. Male and female members of work teams performed a physical persistence task. In one condition they performed work trials as individuals. In others, they first worked on the task alone and then were paired with a more capable same- or other-sexed teammate to perform the task conjunctively - i. e., this trial was over as soon as either person stopped. As expected, these less capable participants worked significantly harder under conjunctive task demands, irrespective of coworker sex. However, also as predicted, males tended to show even greater motivation gain when paired with a more capable female, while females' efforts tended to vary the most when they were paired with a male. Results are discussed in terms of their implications for understanding the potentially multifaceted bases for motivation gains in collective work contexts