Drag estimation on wedge-shaped protuberances in high-speed flows

A semi-empirical method is developed to estimate drag on wedge-shaped projections in hypersonic flow. Force balance measurements from gun tunnel tests directly measure total drag on blunt wedges, where the boundary layer and the entropy layer are weakly coupled. Detailed flowfield analysis from numerical simulations provides estimated locations of peak pressure ratio and skin friction. Schlieren images are used for detecting incipient separation in incoming flows with laminar and turbulent boundary layers. Test results indicate the presence of local hotspots at reattachment points of strong detached shocks on the wedge compression ramp, and of primary and secondary vortical structures around lateral faces. Total drag is found to decrease with decreasing bluntness but increasing slenderness in wedges tend to increase skin friction drag

Scaling analysis of a divergent prefactor in the metastable lifetime of a square-lattice Ising ferromagnet at low temperatures

We examine a square-lattice nearest-neighbor Ising quantum ferromagnet coupled to $d$-dimensional phonon baths. Using the density-matrix equation, we calculate the transition rates between configurations, which determines the specific dynamic. Applying the calculated stochastic dynamic in Monte Carlo simulations, we measure the lifetimes of the metastable state. As the magnetic field approaches $|H|/J=2$ at low temperatures, the lifetime prefactor diverges because the transition rates between certain configurations approaches zero under these conditions. Near $|H|/J=2$ and zero temperature, the divergent prefactor shows scaling behavior as a function of the field, temperature, and the dimension of the phonon baths. With proper scaling, the simulation data at different temperatures and for different dimensions of the baths collapse well onto two master curves, one for $|H|/J>2$ and one for $|H|/J<2$.Comment: published versio

The self-perceived knowledge, skills and attitudes of Australian practice nurses in providing nutrition care to patients with chronic disease

Background. Nutrition is important for the management of chronic diseases. While practice nurses have numerous roles in primary care, the expectations on practice nurses to provide nutrition care for chronic disease management are increasing. The self-perceived knowledge, skills and attitudes of practice nurses in providing nutrition care has not been widely investigated

Healthy lifestyles are associated with better vitamin D status in community-dwelling older men: The Health In Men Study (HIMS)

Objective: Older people are more prone to vitamin D deficiency than younger populations. Individual lifestyle factors have been associated with vitamin D status. We examined the influence of a combination of lifestyle factors on vitamin D status in older men. Participants and Measurements: In a population-based cohort study of older men (age ≥65 years), a lifestyle score was calculated from eight prudent health-related behaviours (smoking, exercise, alcohol, fish and meat consumption, adding salt, milk choices and obesity) collected via questionnaire at baseline. Blood samples were collected 5 years afterwards to measure plasma 25-hydroxyvitamin D (25OHD) levels. Associations between lifestyles and the likelihood of having plasma 25OHD levels of ≥75 versus <75 nmol/L and ≥50 versus <50 nmol/L were tested using logistic regression models. Results: Of the 2717 men analysed, mean plasma 25OHD was 69.0 ± 23.5 nmol/L, with 20.7% having plasma 25OHD <50 nmol/L. Men engaging in ≥4 healthy lifestyle behaviours had 20% higher odds of plasma 25OHD ≥75 nmol/L (adjusted OR = 1.20, 95% CI: 1.01−1.45) compared to those with <4 healthy behaviours. No association was found for 25OHD ≥50 nmol/L. Higher physical activity was the only individual component significantly associated with vitamin D sufficiency (highest vs. lowest quintiles of physical activity, adjusted OR = 2.01, 95% CI: 1.47−2.74 for 25OHD ≥50 nmol/L, adjusted OR = 2.35, 95% CI: 1.81−3.06 for 25OHD ≥75 nmol/L). Conclusion: Multiple healthy lifestyle behaviours are associated with better vitamin D status in older men. Further work is needed to determine the effects of promoting healthy lifestyle behaviours, including physical activity, on vitamin D sufficiency

Criticality of the Mean-Field Spin-Boson Model: Boson State Truncation and Its Scaling Analysis

The spin-boson model has nontrivial quantum phase transitions at zero temperature induced by the spin-boson coupling. The bosonic numerical renormalization group (BNRG) study of the critical exponents $\beta$ and $\delta$ of this model is hampered by the effects of boson Hilbert space truncation. Here we analyze the mean-field spin boson model to figure out the scaling behavior of magnetization under the cutoff of boson states $N_{b}$. We find that the truncation is a strong relevant operator with respect to the Gaussian fixed point in $0<s<1/2$ and incurs the deviation of the exponents from the classical values. The magnetization at zero bias near the critical point is described by a generalized homogeneous function (GHF) of two variables $\tau=\alpha-\alpha_{c}$ and $x=1/N_{b}$. The universal function has a double-power form and the powers are obtained analytically as well as numerically. Similarly, $m(\alpha=\alpha_{c})$ is found to be a GHF of $\epsilon$ and $x$. In the regime $s>1/2$, the truncation produces no effect. Implications of these findings to the BNRG study are discussed.Comment: 9 pages, 7 figure

Flat Information Geometries in Black Hole Thermodynamics

The Hessian of either the entropy or the energy function can be regarded as a metric on a Gibbs surface. For two parameter families of asymptotically flat black holes in arbitrary dimension one or the other of these metrics are flat, and the state space is a flat wedge. The mathematical reason for this is traced back to the scale invariance of the Einstein-Maxwell equations. The picture of state space that we obtain makes some properties such as the occurence of divergent specific heats transparent.Comment: 14 pages, one figure. Dedicated to Rafael Sorkin's birthda

Statistical analysis plan for the stepped wedge clinical trial Healing Right Way—enhancing rehabilitation services for Aboriginal Australians after brain injury

Background Aboriginal Australians are known to suffer high levels of acquired brain injury (stroke and traumatic brain injury) yet experience significant barriers in accessing rehabilitation services. The aim of the Healing Right Way trial is to evaluate a culturally secure intervention for Aboriginal people with newly acquired brain injury to improve their rehabilitation experience and quality of life. Following publication of the trial protocol, this paper outlines the statistical analysis plan prior to locking the database. Methods The trial involves a stepped wedge design with four steps over 3 years. Participants were 108 adult Aboriginal Australians admitted to one of eight hospitals (four rural, four urban) in Western Australia within 6 weeks of onset of a new stroke or traumatic brain injury who consented to follow-up for 26 weeks. All hospital sites started in a control phase, with the intervention assigned to pairs of sites (one metropolitan, one rural) every 26 weeks until all sites received the intervention. The two-component intervention involves training in culturally safe care for hospital sites and enhanced support provided to participants by Aboriginal Brain Injury Coordinators during their hospital stay and after discharge. The primary outcome is quality of life as measured by the Euro QOL–5D-3L VAS. A mixed effects linear regression model will be used to assess the between-group difference at 26 weeks post-injury. The model will control for injury type and severity, age at recruitment and time since commencement of the trial, as fixed effects. Recruitment site and participant will be included as random effects. Secondary outcomes include measurements of function, independence, anxiety and depression, carer strain, allied health occasions of service received and hospital compliance with minimum processes of care based on clinical guidelines and best practice models of care. Discussion The trial will provide the first data surrounding the effectiveness of an intervention package for Aboriginal people with brain injury and inform future planning of rehabilitation services for this population. The statistical analysis plan outlines the analyses to be undertaken. Trial registration Australia New Zealand Clinical Trials Registry ACTRN12618000139279. Registered 30 January, 2018