Investigating the effects of particle shape on normal compression and overconsolidation using DEM

Discrete element modelling of normal compression has been simulated on a sample of breakable two-ball clumps and compared to that of spheres. In both cases the size effect on strength is assumed to be that of real silica sand. The slopes of the normal compression lines are compared and found to be consistent with the proposed equation of the normal compression line. The values of the coefficient of earth pressure at rest K0,nc are also compared and related to the critical state fiction angles for the two materials. The breakable samples have then been unloaded to establish the stress ratios on unloading. At low overconsolidation ratios the values of K0 follow a well-established empirical relationship and realistic Poisson ratios are observed. On progressive unloading both samples head towards passive failure, and the values of the critical state lines in extension in q–p' space are found to be consistent with the critical state angles deduced from the values of K0 during normal compression. The paper highlights the important role of particle shape in governing the stress ratio during both normal compression and subsequent overconsolidation

Gender differences in recess play in five Fiji primary schools

This study aimed to investigate gender differences in the level of social interaction and types of play and games in which class four pupils in five Fiji primary schools in Suva are engaged during school recess. Five researchers observed 168 (male n = 79, female n = 89) class four pupils over three months, using scan sampling. With a mixed method approach, the study analysed quantitative data using the Kruskal–Wallis test, while qualitative data was gathered via five focus groups with recess observers. Qualitative data derived from these focus groups were used as a smaller component of the study to support quantitative findings in the dominant–less dominant mixed methods study. It was found that boys are significantly into ‘vigorous’ and ‘fantasy’ play more so than girls, while girls are engaged in ‘conversation’ more than boys during recess. This indicates that boys play more vigorous activities during recess than girls. Furthermore, it also indicates that boys may view recess as opportunity to be engaged in vigorous play, while girls may see it as opportunity to socialise with their friends. These and other discussions will have implications for a recess policy in Fiji

Dimerisation of N-acetyl-L-tyrosine ethyl ester and Aß peptides via formation of dityrosine

Alzheimer\u27s disease (AD) is characterised by the formation of amyloid deposits composed primarily of the amyloid &beta;-peptide (A&beta;). This peptide has been shown to bind redox active metals ions such as copper and iron, leading to the production of reactive oxygen species (ROS) and formation of hydrogen peroxide (H2O2). The generation of H2O2 has been linked with A&beta; neurotoxicity and neurodegeneration in AD. Because of the relative stability of a tyrosyl radical, the tyrosine residue (Tyr-10) is believed to be critical to the neurotoxicity of A&beta;. This residue has also been shown to be important to A&beta; aggregation and amyloid formation. It is possible that the formation of an A&beta; tyrosyl radical leads to increased aggregation via the formation of dityrosine as an early aggregation step, which is supported by the identification of dityrosine in amyloid plaque. The role of dityrosine formation in A&beta; aggregation and neurotoxicity is as yet undetermined, partly because there are no facile methods for the synthesis of A&beta; dimers containing dityrosine. Here we report the use of horseradish peroxidase and H2O2 to dimerise N-acetyl-l-tyrosine ethyl ester and apply the optimised conditions for dityrosine formation to fully unprotected A&beta; peptides. We also report a simple fluorescent plate reader method for monitoring A&beta; dimerisation via dityrosine formation. <br /

Self-regulation and obesity: the role of executive function and delay discounting in the prediction of weight loss

© 2018 The Author(s) Obesity rates are rising worldwide. Executive function and delay discounting have been hypothesized to play important roles in the self-regulation of behavior, and may explain variance in weight loss treatment success. First, we compared individuals with obesity (n = 82) to healthy weight controls (n = 71) on behavioral and self-report measures of executive function (working memory, inhibition and shifting) and delay discounting. Secondly, the individuals with obesity took part in a multidisciplinary weight loss program and we examined whether executive function and delay discounting predicted weight change. Individuals with obesity displayed weaker general and food-specific inhibition, and weaker self-reported executive function. Better behavioral working memory and better self-reported inhibition skills in daily life were predictive of greater weight loss. As findings are correlational, future studies should investigate the causal relationship between executive function and weight loss, and test whether intervening on executive function will lead to better prevention and treatment of obesity