The Turbulent Story of X-ray Bursts: Effects of Shear Mixing on Accreting Neutron Stars

During accretion, a neutron star (NS) is spun up as angular momentum is transported through its liquid surface layers. We study the resulting differentially rotating profile, focusing on the impact this has for type I X-ray bursts. The viscous heating is found to be negligible, but turbulent mixing can be activated. Mixing has the greatest impact when the buoyancy at the compositional discontinuity between accreted matter and ashes is overcome. This occurs preferentially at high accretion rates or low spin frequencies and may depend on the ash composition from the previous burst. We then find two new regimes of burning. The first is ignition in a layer containing a mixture of heavier elements with recurrence times as short as ~5-30 minutes, similar to short recurrence time bursts. When mixing is sufficiently strong, a second regime is found where accreted helium mixes deep enough to burn stably, quenching X-ray bursts altogether. The carbon-rich material produced by stable helium burning would be important for triggering and fueling superbursts.Comment: 3 pages, 3 figures. To appear in the proceedings of "Forty Years of Pulsars: Millisecond Pulsars, Magnetars and More" held in Montreal, Canada, August 12-17, 200

Protein sliding and hopping kinetics on DNA

Using Monte-Carlo simulations, we deconvolved the sliding and hopping kinetics of GFP-LacI proteins on elongated DNA from their experimentally observed seconds-long diffusion trajectories. Our simulations suggest the following results: (1) in each diffusion trajectory, a protein makes on average hundreds of alternating slides and hops with a mean sliding time of several tens of ms; (2) sliding dominates the root mean square displacement of fast diffusion trajectories, whereas hopping dominates slow ones; (3) flow and variations in salt concentration have limited effects on hopping kinetics, while in vivo DNA configuration is not expected to influence sliding kinetics; furthermore, (4) the rate of occurrence for hops longer than 200 nm agrees with experimental data for EcoRV proteins

Gender differences in the influence of food safety and health concerns on dietary and physical activity habits

MONOGRAFÍ

The relationships between eating habits, smoking and alcohol consumption, and body mass index among baby boomers

The study was to examine the eating habits of baby boomers and to investigate the relationship of these and other lifestyle habits on their reported body mass indices (BMI). A questionnaire was administered by mail to a random sample of people aged 40 years and above, drawn from the Electoral Rolls in Victoria, Australia. Part of the questionnaire contained questions about the respondents’ eating habits, smoking status and alcohol use, as well as self reported heights and weights and demographic characteristics. Eight hundred and forty-four people (out of 1470) returned usable questionnaires. Statistically significant differences were found between the eating habits of men and women. Generally, more women snacked on high energy dense foods (e.g., confectionery). More men took larger mouthfuls than women. The eating habits of women appeared to be more formal than men’s. Four constructs named: unconstrained eating, traditional eating style, gulping, and chocolate and junk food were derived from the eating behaviour literature. Structural equation modelling showed that eating behaviour was associated with BMI along with current smoking, ex-smoking status, alcohol consumption, and demographics. Eating habits and other lifestyle behaviours appear to be associated with BMI though in different pathways for men and women

Towards a Real-Time Data Driven Wildland Fire Model

A wildland fire model based on semi-empirical relations for the spread rate of a surface fire and post-frontal heat release is coupled with the Weather Research and Forecasting atmospheric model (WRF). The propagation of the fire front is implemented by a level set method. Data is assimilated by a morphing ensemble Kalman filter, which provides amplitude as well as position corrections. Thermal images of a fire will provide the observations and will be compared to a synthetic image from the model state.Comment: 5 pages, 4 figure

Social ideological influences on reported food consumption and BMI

Background : The purpose of this study was to investigate relationships between ideological beliefs, perceptions of the importance of health behaviours, health attitudes, food consumption, and Body Mass Index (BMI). A behavioural model was hypothesized based on the Theory of Reasoned Action (Fishbein &amp; Ajzen, 1975). Methods : A survey was conducted among shoppers aged between 40 and 70 years at Eastland Shopping Centre, Melbourne, Australia. The hypothesized model was tested with this empirical data (n = 410) for younger (n = 151) and older (n = 259) age groups using structural equation modelling. Results : The findings generally support the study hypotheses. For both groups, egalitarianism had a direct and positive influence on perceptions of the importance of health behaviours. Materialism and masculinity impacted negatively on health attitudes, which positively influenced importance of health behaviours. Perceptions of importance of health behaviours impacted positively on the consumption of healthy foods such as vegetables and fruits, but negatively on consumption of unhealthy foods including sweets and fats. However, BMI was significantly influenced by the consumption of unhealthy foods (e.g., sugar and fats) only for the younger age group. Hence, the associations between beliefs, attitudes, consumption behaviours, and BMI outcomes differed between younger and older age populations. Conclusion : Social ideological beliefs appear to influence health attitudes and thereafter, the consumption of healthy and unhealthy foods and BMI via different pathways.<br /