Ostracism arouses negative affect. However, little is known about variables that influence the intensity of these negative affective responses. Two studies seek to fill this void by incorporating work on approach- and withdrawal-related emotional states and their associated cortical activations. Study 1 found that following ostracism, anger related directly to relative left frontal cortical activation. Study 2 used unilateral hand contractions to manipulate frontal cortical activity prior to an ostracizing event. Righthand contractions, compared to left-hand contractions, caused greater relative left frontal cortical activation during the hand contractions as well as during ostracism. Also, righthand contractions caused more self-reported anger in response to being ostracized. Within-condition correlations revealed patterns of associations between ostracisminduced frontal asymmetry and emotive responses to ostracism consistent with Study 1. Taken together, these results suggest that asymmetrical frontal cortical activity affects angry responses to ostracism, with greater relative left frontal cortical activity being associated with increased anger.

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Clusters of galaxies are particularly interesting astrophysical systems, are the largest bound structures in the Universe, and contain fair sample of cosmic ingredients. Studies of cluster abundance as a function of mass and redshift were critical in establishing the standard model of cosmology. This dissertation presents results from X-ray imaging of massive distant (M > 10^14 M; 0:3 < z < 1.2) clusters, found via X-ray emission or Sunyaev-Zeldovich eff ect. This is the world's largest sample of massive galaxy clusters. We explore the radial and azimuthal profi les of the X-ray emitting gas and show that clusters are self-similar objects: their internal structure is largely independent of the cluster's mass or redshift, and the fractions of di fferent types of clusters does not change with redshift. We also present a new statistical technique for measuring a cluster's deviations from a perfect axisymmetric shape, which is especially useful in the case of low photon count observations of distant clusters. / Physics

Purpose: The aim of this research was to examine the relationship between stuttering and bilingualism to hemispheric asymmetry for the processing and production of language. Methods: A total of 80 native speakers of German were recruited for the study, ranging in age from 15 to 58 years. Out of those 80 participants, 40 participants were also proficient speakers of English as a second language (L2). The participants were organised into four speaker groups (20 per group) according to language ability and speech status, consisting of monolinguals who stutter (MWS), monolinguals who do not stutter (MWNS), bilinguals who stutter (BWS), and bilinguals who do not stutter (BWNS). Each of the four groups comprised 12 males and 8 females. All participants completed a battery of behavioural assessments measuring functional cerebral hemispheric asymmetry during language processing and production. The behavioural tests included (1) a dichotic listening paradigm, (2) a visual hemifield paradigm, and (3) a dual-task paradigm. Results: Overall, the results showed no significant differences in language lateralisation between participant groups on the three behavioural tests. However group differences were identified in regard to executive functions on the visual hemifield and dual-task paradigms. Both bilingual groups showed significantly faster reaction times and fewer errors than the two monolingual groups on the visual hemifield paradigm. The bilingual groups also performed similarly on the dual-task paradigm, while the MWS group tended to show greater task disruption. No meaningful relationship was found between stuttering severity and the majority of results obtained for the test conditions. However, all four language modalities were found to correlate significantly with results obtained for the visual hemifield and dual-task paradigms, suggesting that performance on these tests increased with higher L2 proficiency. Conclusion: Although no differences in language lateralisation were found, it appears that bilingualism had a greater influence on functional cerebral hemispheric processing than stuttering. A prevailing finding was that bilingualism seems to be able to offset deficits in executive functioning associated with stuttering. Brain reserve and cognitive reserve are thought to have a close interrelationship with the executive control system. Cognitive reserve may have been reflected in the present study, resulting in a bilingual cognitive advantage. Hence, the results of the present study lend support to previous findings implicating the benefits of bilingualism.

The heritability of frontal EEG asymmetry, a potential endophenotype for depression, was investigated using a large set of adolescent and young adult twins. Additionally, the relationship between polymorphisms within three serotonin genes, two receptor genes and one transporter gene, and frontal EEG asymmetry was also investigated. Using Falconer's estimate, frontal EEG asymmetry was shown to be more heritable at lateral compared to medial cites across nearly all reference montages, and greater in males compared to females. Using structural equation modeling (SEM), and investigating both additive (ACE) and non-additive (ADE) models of genetic heritability, males displayed consistently greater additive genetic contributions to heritability, with greater lateral contributions than medial ones. For female twins pairs, the additive genetic model data provided a mixed picture, with more consistent heritability estimates observed at medial sites, but with larger estimates shown at lateral channels. For non-additive genetic models, male twin pairs demonstrated exclusive non-additive contributions to heritability across channels within AVG and CZ referenced data, with metrics in the CSD and LM montages more mixed between additive and non-additive contributions. However, consistent with Falconer's estimates, lateral channels were nearly always estimated to be more heritable than medial channels regardless of gender. These models demonstrate some combination of additive and non-additive contributions to the heritability of frontal EEG asymmetry, with the CSD and AVG montages showing greater lateral compared to medial heritability and CZ and LM montages showing mixed contributions with additive heritability at lateral channels and non-additive primarily at medial channels. The complex interaction of gender and reference montage on the heritability estimates highlight the subtle yet important roles of age, gender, and recording methodology when investigating proposed endophenotypes. However, no association was found between the proposed polymorphisms in serotonin receptor 1a, 2a or serotonin transporter genes and frontal EEG asymmetry. Although the results support modest heritability of frontal EEG asymmetry, the proposed link to underlying serotonergic genetic markers remains an open question. Overall, these results indicate that frontal asymmetry may be a useful endophenotype for depressive risk with modest heritability, but is one that taps more environmental risk.

Frontal encephalographic (EEG) alpha asymmetry has been proposed as a measure of the relative difference in average cortical activity between the right and left anterior cortex, where this difference is taken as a physiological marker of trait and state level variables associated with affect. The validity of asymmetry as an indicator of both physiological and psychological variables is in part determined by the psychometric properties of asymmetry scores. The present studies focus on the psychometric assessment of frontal alpha asymmetry measured during rest. The first study involves a novel approach in the assessment of the internal consistency reliability of asymmetry scores. Previous studies estimated internal consistency reliability via Cronbach's alpha, using a relatively small set of asymmetry score that summarized activity over segments of the EEG data (e.g. one minute). Such an approach, however, will create estimates dependent on the number of segments utilized rather than the total amount of data recorded. Thus in the first study, individual FFT epochs were treated as items, thereby maximizing the total number of items used to estimate internal consistency reliability. Results of this study suggest internal consistency reliability is greater than previously reported, and as such, the duration of resting EEG data necessary to achieve a reasonable reliability criterion may be shorter than the current standard. In the second study, asymmetry scores were assessed as a specific case of difference scores, which are susceptible to a statistical artifact associated with differences in true-score variance for the component measures. Predicted asymmetry scores associated with the statistical artifact were obtained by estimating the true-score variance of right and left alpha power. The use of hierarchical linear regression showed some influence of the statistical artifact on the relationship between asymmetry scores and a measure of depressive severity, suggesting that some caution may be warranted in interpreting asymmetry results with relatively small effect sizes.

Walking is an essential task important to recovery after stroke. However, there is a limited understanding regarding the characteristics of walking in in-patients with stroke. The objectives of this thesis were to: 1) develop an instrument capable of acquiring temporal characteristics of everyday walking; 2) investigate the quantity and control of everyday walking; and 3) profile the task-specific link between walking and cardiorespiratory response. In study 1 we developed and validated a wireless monitoring system (ABLE system). Study 2 revealed low quantities of everyday walking (4816 steps; SD 3247) characterized by short bout durations (59.8s; SD 23.4) and asymmetric walking. In study 3 we observed a modest task-related response in HR(19.4% HRR); however, the intensity and duration of everyday walking did not approach the guidelines for aerobic benefit. Monitoring in-patient walking can help guide clinical decision making in developing methods to maximize recovery after stroke.

Past research has indicated that Chinese culture is more past oriented; whereas North American culture is more future oriented. Such cultural differences in temporal orientation may affect how people value future and past events. I predicted that the typical temporal asymmetry effect among European North Americans - placing more value on future events than on past ones - would be reversed among Chinese due to the cultural differences in temporal orientation. I conducted four studies to examine how culture affects the values people attached to past and future events. Overall, the results supported my predictions. Across all four studies, I found that European Canadians attached more monetary value to an event in the future than to an identical event in the past with similar temporal distance; whereas Chinese people placed more monetary value on a past event than on an identical future event. In Study 3, I also investigated the underlying mechanisms that would account for such cultural differences. Among the three mediators believed to be affected by the past and future orientations, I found two that mediated the cultural influences on the temporal value asymmetry effect: (1) emotions associated with future and past events, and (2) mental simulations of future and past events. Specifically, European Canadians predicted stronger emotions for future events than what they recalled for past events, whereas Chinese showed an opposite trend. Emotions associated with future or past events, in turn, predicted the monetary values attached to the events. In addition, relative to Chinese Canadians, who showed clearer mental simulations for past than for future events, European Canadians had clearer mental simulations for future than for past events. Mental simulations, in turn, showed a positive association with the monetary value assigned to the events. / Thesis (Ph.D, Psychology) -- Queen's University, 2008-09-26 16:18:09.371

The purpose of this study is to investigate the impact of litigiousness on the information role of accounting conservatism. Prior literature documents the information role of accounting conservatism, measured by the positive association between earnings conservatism and information asymmetry between inside managers and outside investors. Prior literature also demonstrates that shareholder litigation concerns motivate managers and auditors to be conservative in preparing financial statements because conservatism shields managers and auditors from allegations that they overstated earnings and net assets. In a more litigious environment, both managers and auditors have incentives to be more sensitive to expected litigation costs, which increase with the level of information asymmetry. I hypothesize that higher levels of litigiousness enhance the information role of accounting conservatism. Overall empirical results are generally consistent with the hypothesis. / Thesis (Ph.D, Management) -- Queen's University, 2010-09-29 17:59:20.556