Attentional avoidance of high-fat food in unsuccessful dieters

Using the exogenous cueing task, this study examined whether restrained and disinhibited eaters differ in their orientation of attention towards and their difficulty to disengage from high versus low-fat food pictures in a relatively short (500 ms) and a long presentation format (1500 ms). Overall, participants in the 500 ms condition showed a tendency to direct attention away from high-fat food pictures compared to neutral pictures. No differential pattern was evident for the 1500 ms condition. Correlational analysis revealed that reduced engagement with high-fat food was particularly pronounced for disinhibited eaters. Although in the short term this seems an adaptive strategy, it may eventually become counterproductive, as it could hinder habituation and learning to cope with seductive characteristics of high-fat food. (C) 2010 Elsevier Ltd. All rights reserved

Host Plant Adaptation in the Two Strains of Fall Armyworm (Lepidoptera: Noctuidae).

The fall armyworm (Spodoptera frugiperda J. E. Smith) Lepidoptera: Noctuidae) consists of two genetically differentiated strains. The corn strain feeds on corn and the rice strain feeds primarily on rice and forage grasses. My research focused on host plant adaptations within each strain as assessed by larval performance and enzymatic responses to feeding upon different hosts. Three sets of experiments were conducted. The first experiment examined consumption and utilization in both strains reared on corn. In the second experiment, mixed-function oxidase (MFO) and general esterase enzyme activities were measured from larvae of both strains that were reared on corn, bermudagrass, or artificial diet. In the third experiment, larvae of both strains were selected for increased larval weight, and associated changes in MFO activities were measured after subsequent feeding upon several hosts. In the first experiment I determined that, when reared on corn, the corn strain had higher pupal weights and accumulated more biomass during the last instar than the rice strain. This resulted primarily from higher consumption in the corn strain. In addition, the corn strain was more efficient in converting digested food into biomass than the rice strain. Thus, there are differences in both feeding behavior and nutritional physiology between the strains feeding on corn. The results from the second experiment indicated that the corn strain had a higher MFO activity than the rice strain when reared on corn or bermudagrass. This result was predicted since there are more reported allelochemicals in corn than in bermudagrass. Within the corn strain, MFO activity was higher when reared on corn than on bermudagrass. Thus, corn plants affected expression of MFO activity only in corn strain larvae. In the rice strain, MFO activity was similar on both hosts. Esterase activity did not differ between strains or host plants. In the third experiment, lines selected on corn expressed higher MFO activity than either a line selected on bermudagrass, or a control. Differences in larval performance were minor. These results suggest there is genetic variation in MFO activity that could play a role in host plant adaptation

Determining the Surface-To-Bulk Progression in the Normal-State Electronic Structure of Sr2RuO4 by Angle-Resolved Photoemission and Density Functional Theory

In search of the potential realization of novel normal-state phases on the surface of Sr2RuO4 - those stemming from either topological bulk properties or the interplay between spin-orbit coupling (SO) and the broken symmetry of the surface - we revisit the electronic structure of the top-most layers by ARPES with improved data quality as well as ab-initio LDA slab calculations. We find that the current model of a single surface layer (\surd2x\surd2)R45{\deg} reconstruction does not explain all detected features. The observed depth-dependent signal degradation, together with the close quantitative agreement with LDA+SO slab calculations based on the LEED-determined surface crystal structure, reveal that (at a minimum) the sub-surface layer also undergoes a similar although weaker reconstruction. This points to a surface-to-bulk progression of the electronic states driven by structural instabilities, with no evidence for Dirac and Rashba-type states or surface magnetism.Comment: 4 pages, 4 figures, 1 table. Further information and PDF available at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm

Testing how teachers’ self-efficacy and student-teacher relationships moderate the association between bullying, victimization, and student self-esteem

This study investigated how teachers’ self-efficacy for intervening in social dynamics and teacher-student relationships directly impact students’ self-esteem, and indirectly buffer the negative association between both bullying and victimization and students’ self-esteem. Teachers play a key role in shaping the peer relations in the classroom, and they might also be able to lessen the negative impact of bullying and victimization on students’ self-esteem. Multilevel regression analysis on a sample of 59 Dutch teachers and 1,490 of their 5th grade students indicated that student-reported bullying and victimization were negatively related to students’ self-reported self-esteem. Better student-perceived student-teacher relationships were related to higher self-esteem for all students, with additional increases in self-esteem for victims but decreases in the self-esteem of bullies. Teacher-reported self-efficacy was only related to lower self-esteem in bullies. Implications of these results and suggestions for further research are discussed

Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap

We study Na2IrO3 by ARPES, optics, and band structure calculations in the local-density approximation (LDA). The weak dispersion of the Ir 5d-t2g manifold highlights the importance of structural distortions and spin-orbit coupling (SO) in driving the system closer to a Mott transition. We detect an insulating gap {\Delta}_gap = 340 meV which, at variance with a Slater-type description, is already open at 300 K and does not show significant temperature dependence even across T_N ~ 15 K. An LDA analysis with the inclusion of SO and Coulomb repulsion U reveals that, while the prodromes of an underlying insulating state are already found in LDA+SO, the correct gap magnitude can only be reproduced by LDA+SO+U, with U = 3 eV. This establishes Na2IrO3 as a novel type of Mott-like correlated insulator in which Coulomb and relativistic effects have to be treated on an equal footing.Comment: Accepted in Physical Review Letters. Auxiliary and related material can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm

Halo and association effects:Cognitive biases in teacher attunement to peer-nominated bullies, victims, and prosocial students

This study examined whether teachers’ perceptions of students’ behavior (referring to halo effects) and the behavior of teacher-perceived friends (referring to association effects) influenced teachers’ ability to recognize students identified as bullies, victims, and prosocial by their peers. Data came from 1,458 children (Mage = 10.5, 47.5% girls) and 56 teachers (Mage = 40.8, 66.1% females). Perceived likeability was associated with decreased odds and teachers’ perceptions of popularity and externalizing behavior were associated with increased odds for teacher attunement to bullying. Perceived likeability and affiliation were associated with decreased odds for teacher attunement to victimized students. Teachers’ perceptions of externalizing behavior were associated with decreased odds, whereas teachers’ perceptions of affiliation and academic competence were associated with increased odds for attunement to prosociality. Finally, a positive association was found between teacher attunement and the average behavior of teacher-perceived friends for bullying, victimization, and prosociality