Grain Size and Parameter Recovery with TIMSS and the General Diagnostic Model

The purpose of this study was to explore the degree of grain size of the attributes and the sample sizes that can support accurate parameter recovery with the General Diagnostic Model (GDM) for a large-scale international assessment. In this resampling study, bootstrap samples were obtained from the 2003 Grade 8 TIMSS in Mathematics at varying sample sizes from 500 to 4000 and grain sizes of the attributes from a unidimensional model to one with ten attributes. The results showed that the eight-attribute model was the one most consistently identified as best fitting. Parameter estimation for more than ten attributes and samples less than 500 failed. Furthermore, the precision of item parameter recovery decreased as the number of attributes measured by an item increased and sample size decreased. On the other hand, the distributions of latent classes were relatively stable across all models and sample sizes.     

“Big” Sounds Bigger in More Widely Spoken Languages

Larger communities face more communication barriers. We propose that languages spoken by larger communities adapt and overcome these greater barriers by increasing their reliance on sound symbolism, as sound symbolism can facilitate communication. To test whether widely spoken languages are more sound symbolic, participants listened to recordings of the words big and small in widely spoken and less common languages and guessed their meanings. Accuracy was higher for words from widely spoken languages providing evidence that widely spoken languages harbor more sound symbolism. Preliminary results also suggest that widely spoken languages rely on different sound symbolic patterns than less common languages. Community size can thus shape linguistic forms and influence the tools that languages use to facilitate communication.     

Sample size determination for a matched-pairs study with incomplete data using exact approach

This research was motivated by a clinical trial design for a cognitive study. The pilot study was a matched-pairs design where some data are missing, specifically the missing data coming at the end of the study. Existing approaches to determine sample size are all based on asymptotic approaches (e.g., the generalized estimating equation (GEE) approach). When the sample size in a clinical trial is small to medium, these asymptotic approaches may not be appropriate for use due to the unsatisfactory Type I and II error rates. For this reason, we consider the exact unconditional approach to compute the sample size for a matched-pairs study with incomplete data. Recommendations are made for each possible missingness pattern by comparing the exact sample sizes based on three commonly used test statistics, with the existing sample size calculation based on the GEE approach. An example from a real surgeon-reviewers study is used to illustrate the application of the exact sample size calculation in study designs.     

Self-Concepts of Hospitalized and Day-Care Psychiatric Patients

Abstract

The authors administered questionnaires to 44 hospitalized and 55 day-care psychiatric patients in Hong Kong. The groups were similar in sex, age, and education. The hospitalized participants, compared with the day-care participants, showed significantly higher self-concepts in general as well as in the particular aspects of social and personal aspirations. The findings indicate that support at the community level is important to help the psychiatric patients' transition from hospital care to day care.     

More Than Just Skin Deep? Personality Information Influences Men's Ratings of the Attractiveness of Women's Body Sizes

ABSTRACT

This study examined the influence of personality information on perceptions of the physical attractiveness of a range of female body sizes. A sample of 2,157 male university students were randomly assigned to one of 10 groups in which they received personality information about women they were rating, or a control group in which they received no personality information. Controlling for participants' age and body mass index, results showed no significant between-group differences in the body size that participants found most attractive. However, participants provided with positive personality information perceived a wider range of body sizes as physically attractive compared with the control group, whereas participants provided with negative personality information perceived a narrower range of body sizes as attractive. Correlations showed that participants' own Extraversion was associated with their body size ratings. These results suggest that non-physical cues have an influence on the perception of physical beauty.     

Body weight, not facial width-to-height ratio, predicts aggression in pro hockey players

Studies indicate that facial characteristics may predict behavior, but it is unclear if this will hold within highly selective populations. One relevant characteristic is the face’s width-to-height ratio (FWHR), a sexually dimorphic trait that has been shown to predict aggression. That FWHR may predict aggression within highly selective populations was suggested by Carré and McCormick’s (2008) finding that professional hockey players with greater FWHRs accrued more penalties. We attempted to replicate this result using all NHL players. We also explored fighting penalties as another aggression measure and height and weight as additional aggression predictors. We found that body weight predicted substantial variance in aggression but FWHR did not. Thus, in highly selective populations, inferences based on faces may be inaccurate.     

New experimental test of strain-gradient plasticity theory: metal foil sandwich structures in flexure

Experimental tests of strain-gradient plasticity theory rely on studies of the size effect (smaller is stronger) in micromechanical testing. The plastic strain gradient is varied by varying the size of the specimen. This confounds the direct effects of the size and the effects of the strain gradient. We propose experiments on foil sandwich structures in which these parameters are separated. Preliminary results suggest that it is the foil thickness that determines the strength, not the strain gradient.     

Vertex interactions and film shapes in two-dimensional foam

A model of the structure of two-dimensional foam (cells separated by circular arcs (films) meeting at threefold vertices) is considered. Films that are so curved as to be nearly semicircular arcs are problematic for conventional foam structure computations, which aim to identify the pressures needed to achieve specified bubble areas. When the films have near semicircularity, tiny variations in pressure can lead to large changes in the computed bubble area, and hence a failure to meet the specified targets. A new algorithm for determining foam structure is presented. It is based on 'freezing' most of the system, except the nearly semicircular arcs, and then finding the particular bubble pressures associated with the latter via an analytic approximation. This procedure is shown to work well for structure relaxation in a small bubble cluster. Large relaxed bubble clusters are considered briefly at the end of the paper.     

Thermodynamics of void nucleation in nanoparticles

The nucleation of voids at the initial stage of hollow nanoshell formation is described in terms of the thermodynamics of nucleation in systems of finite size (or small systems) pumped with vacancies by interdiffusion-driven vacancy influx. Crossovers from suppressed nucleation to metastable nucleus formation and then to stable nucleus formation are analysed, describing, in particular, the possibility of significant supersaturations with vacancies of the metallic core. It is shown that at higher temperatures it becomes more favourable to nucleate at once a large single void instead of multiple tiny voids.