Simulation of percolation on massively-parallel computers

A novel approach to parallelize the well-known Hoshen-Kopelman algorithm has been chosen, suitable for simulating huge lattices in high dimensions on massively-parallel computers with distributed memory and message passing. This method consists of domain decomposition of the simulated lattice into strips perpendicular to the hyperplane of investigation that is used in the Hoshen-Kopelman algorithm. Systems of world record sizes, up to L=4000256 in two dimensions, L=20224 in three, and L=1036 in four, gave precise estimates for the Fisher exponent tau, the corrections to scaling Delta_1, and for the critical number density n_c.Comment: 9 pages, submitted to Int. J. Mod. Phys.

Numerical methods for the determination of the properties and critical behaviour of percolation and the Ising model

For this thesis, numerical methods have been developed, based on Monte Carlo methods, which allow for investigating percolation and the Ising model with high precision. Emphasis is on methods to use modern parallel computers with high efficiency. Two basic approaches for parallelization were chosen: replication and domain decomposition, in conjunction with suitable algorithms. For percolation, the Hoshen-Kopelman algorithm for cluster counting was adapted to different needs. For studying fluctuations of cluster numbers, its traditional version (i. e., which is already published in literature) was used with simple replication. For simulating huge lattices, the Hoshen-Kopelman algorithm was adapted to domain decomposition, by dividing the hyperplane of investigation into strips that were assigned to different processors. By using this way of domain decomposition, it is viable to simulate huge lattices (with world record sizes) even for dimensions d greater than 2 on massively-parallel computers with distributed memory and message passing. For studying properties of percolation in dependence of system size, the Hoshen-Kopelman algorithm was modified to work on changing domains, i. e., growing lattices. By using this method, it is possible to simulate a lattice of linear size Lmax and investigate lattices of size L less than Lmax for free. Here again, replication is a viable parallelization strategy. For the Ising model, the standard Monte Carlo method of importance sampling with Glauber kinetics and multi-spin coding is adapted to parallel computers by domain decomposition of the lattice into strips. Using this parallelization method, it is possible to use massively-parallel computers with distributed memory and message passing in order to study huge lattices (again world record sizes) over many Monte Carlo steps, in order to investigate the dynamical critical behaviour in two dimensions

"Appearance potent"? A content analysis of UK gay and straight men's magazines.

With little actual appraisal, a more 'appearance potent' (i.e., a reverence for appearance ideals) subculture has been used to explain gay men's greater body dissatisfaction in comparison to straight men's. This study sought to assess the respective appearance potency of each subculture by a content analysis of 32 issues of the most read gay (Attitude, Gay Times) and straight men's magazines (Men's Health, FHM) in the UK. Images of men and women were coded for their physical characteristics, objectification and nudity, as were the number of appearance adverts and articles. The gay men's magazines featured more images of men that were appearance ideal, nude and sexualized than the straight men's magazines. The converse was true for the images of women and appearance adverts. Although more research is needed to understand the effect of this content on the viewer, the findings are consistent with a more appearance potent gay male subculture

Possible involvement of a calmodulin regulated Ca2+-ATPase in exocytosis performance in Paramecium tetraurelia cells

AbstractSurface membrane fractions from Paramecium tetraurelia cells contain a calmodulin-stimulated Ca2+-ATPase responding to low levels of free Ca2+ and with features characteristic of a membrane-bound ATPase responding to low levels of free Ca2+ and with features characteristics of a membrane-bound ATPase. Among the different strains analyzed this enzyme was practically absent selectively from the ‘non-discharge” mutant nd9—28°C (from J. Beisson); if cultured at a permissive temperature (18°C), this strain showed identical values of calmodulin-stimulated Ca2+-ATPase activity as wild-type cells (7S) or strains with mutations which do not affect exocytosis performance. We conclude that this calmodulin-stimulated Ca2+-activated ATPase might be a prerequisite for membrane fusion in the course of exocytosis performance

The role of perfectionism in body dissatisfaction

Body dissatisfaction is a robust risk factor for disordered eating and is thought to be especially problematic in the presence of high levels of perfectionism. The aim of the current study was to investigate what types of perfectionism were associated with body dissatisfaction. Participants were 1083 women aged 28 to 40 years, with a mean age of 35 years (SD=2.11). Self-reports on perfectionism (using the Frost Multidimensional Perfectionism Scale), weight, height, desired weight, and current and ideal figural stimuli were analysed for the current study. Two measures of body dissatisfaction were utilised: discrepancy between the current and desired weight, and discrepancy between the current and ideal figural stimuli. Results: Linear regressions controlling for current body mass index (BMI)/current silhouette examined the relationship between desired BMI/silhouette and simultaneous entry of the 6 sub-scales of the perfectionism measure. A lower desired BMI was associated with higher levels of Concern over Mistakes and Organisation, and a smaller ideal silhouette was associated with higher levels of Concern over Mistakes and Doubt about Actions and Organisation. Conclusions: These findings confirm the pertinence of different dimensions of perfectionism to body dissatisfaction, and suggest avenues to explore in terms of universal prevention work.Grant 160009 from the National Health and Medical Research Council (NHMRC) supported this work. The authors would like to thank the twins for their participation in this research, and Ms Jacqueline Bergin for coordinating the data collection. Administrative support for data collection was received from the Australian Twin Registry that is supported by an Enabling Grant (ID 310667) from the NHMRC administered by the University of Melbourne. Publication costs of this research were supported by the National Eating Disorders Collaboration

Approach bias for food cues in obese individuals

This study aimed to investigate the existence of an approach bias for food cues in obese individuals. A community sample of 56 obese women and 56 normal weight controls completed an approach–avoidance variant of the implicit association task. The obese participants were faster to respond to trials that paired food words with approach words, and trials that paired non-food words with avoid words, than the converse pairings, thus, demonstrating an approach bias for food. This bias was evident for both high caloric and low caloric food words, and was not attributable to a state of deprivation or feelings of hunger. By contrast, the normal weight controls did not show any such bias. The results are consistent with recent neurocognitive perspectives of obesity. At a practical level, approach biases for food may present a potential target for modifying (excessive) food intake

Olfactory stimulation curbs food cravings

Author version made available in accordance with the publisher's policy for non-mandated open access submission. Under Elsevier's copyright, non-mandated authors are permitted to make work available in an institutional repository.Based on the logic of mutual competition between cravings and odours for limited-capacity resources, this study investigated whether a simple olfactory task, involving a brief odour exposure, could reduce food cravings. In support, Experiment 1 showed that smelling a neutral unfamiliar odorant reduced cravings for highly desired food items, relative to a comparison auditory task and a no-task control condition. Experiment 2 replicated these findings specifically for chocolate cravings, which can be particularly problematic. Thus olfactory stimulation offers potential scope for curbing unwanted food cravings. Keywords: craving; food; odour; craving reductio

A Cognitive Experimental Approach to Understanding and Reducing Food Cravings

Author version made available in accordance with the publisher's policy.Food cravings are a common everyday experience. Yet, they can pose significant health risks for some people. Following initial investigations into the phenomenology, antecedents and consequences of food cravings, recent scientific interest has turned to the underpinnings of the actual craving experience itself. In this article, we outline a conceptual framework for studying food cravings that is grounded in cognitive experimental psychology, along with our corresponding program of research. In particular, we present converging evidence from a number of seemingly disparate lines of research into the cognitive processes that underlie food cravings with a view to developing a craving-reduction technique

A qualitative exploration of whether lesbian and bisexual women are 'protected' from sociocultural pressure to be thin

Heterosexual women in Western cultures are known to experience body image concerns, dieting and disordered eating as a result of intense social pressures to be thin. However, it is theorised that lesbian and bisexual women belong to a subculture that is ‘protective’ of such demands. Fifteen non-heterosexual women were interviewed about their experiences of social pressure. Thematic analysis of their accounts suggests that such theorising may be inaccurate, because these lesbian and bisexual women did not feel ‘protected’ from social pressures and experienced body dissatisfaction. While they might attempt to resist thin idealisation, resistance is not centred around their sexuality