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

Different patterns of Australian adults\u27 knowledge of foods and nutrients related to metabolic disease risk

A nationwide survey of 2022 consumers was conducted in Australia in late 2011. A short list of questions about knowledge of the nutrient composition of common foods was administered along with questions about the respondents’ food attitudes, demographics, school education and dieting practices. Overall, the results showed that nutrition knowledge was relatively high. Latent class analysis showed two groups of consumers with ‘high’ and ‘low’ knowledge of nutrition. Higher knowledge was positively associated with age, female sex, university education, experience of home economics or health education at school, having a chronic disease, and attitudes to food issues, and negatively with type 1 diabetes or the use of diabetes-control diets. The implications of the findings for nutrition communication are discussed