A time-stepping dynamically-consistent spherical-shell dynamo code

A pseudo-spectral dynamo code, developed as a computational laboratory, is described. The magnetic, heat and Boussinesq Navier-Stokes equations, with inertia, non-linear advection, buoyancy with asymmetric gravity, Coriolis, viscous and Lorentz forces, are solved numerically in a rotating conducting fluid shell. The convection is thermally driven by prescribed boundary temperatures. The equations are discretised using toroidal-poloidal fields, Chebychev collocation in radius and spherical harmonic expansion in angles. Derivatives are performed spectrally. Products are evaluated in physical space for efficiency. Fields are transformed between physical and spectral spaces by fast Fourier and Gauss-Legendre methods. Linear terms are time-stepped implicitly and product terms explicitly using an Adams predictor/corrector. Results are presented for two benchmark models

Channelling the force of audit and feedback : averting the dark side

Funding EMD is funded through a personal fellowship from the Healthcare Improvement Studies Institute, supported by the Health Foundation’s grant to the University of Cambridge. JMG holds a Canada Research Chair in Health Knowledge Transfer and Uptake. NMI holds a Canada Research Chair in Implementation of Evidence-based PracticePeer reviewedPostprin

Morning quiet-time ionospheric current reversal at mid to high latitudes

The records of an array of magnetometers set up across the Australian mainland are examined. In addition to a well-defined current whorl corresponding to the ionospheric <i>S<sub>q</sub></i> current system, another system of eastward flowing currents is often found in the early morning. The system is most easily identified at observatories poleward of the focus of the <i>S<sub>q</sub></i> system, where a morning reversal from eastward to westward currents can be seen. The time of the reversal is usually later, sometimes up to 12h local noon, in June (Southern Winter) than in other seasons. There is some evidence of a similar current system at other longitudes and in the Northern Hemisphere. An important outcome of the study is that it enables identification of which features of a daily variation of the northward magnetic field Δ<i>X</i> relate to an <i>S<sub>q</sub></i> current whorl and which must be attributed to some other current system

Magnetohydrodynamic activity inside a sphere

We present a computational method to solve the magnetohydrodynamic equations in spherical geometry. The technique is fully nonlinear and wholly spectral, and uses an expansion basis that is adapted to the geometry: Chandrasekhar-Kendall vector eigenfunctions of the curl. The resulting lower spatial resolution is somewhat offset by being able to build all the boundary conditions into each of the orthogonal expansion functions and by the disappearance of any difficulties caused by singularities at the center of the sphere. The results reported here are for mechanically and magnetically isolated spheres, although different boundary conditions could be studied by adapting the same method. The intent is to be able to study the nonlinear dynamical evolution of those aspects that are peculiar to the spherical geometry at only moderate Reynolds numbers. The code is parallelized, and will preserve to high accuracy the ideal magnetohydrodynamic (MHD) invariants of the system (global energy, magnetic helicity, cross helicity). Examples of results for selective decay and mechanically-driven dynamo simulations are discussed. In the dynamo cases, spontaneous flips of the dipole orientation are observed.Comment: 15 pages, 19 figures. Improved figures, in press in Physics of Fluid

Impact of CONSORT extension for cluster randomised trials on quality of reporting and study methodology : review of random sample of 300 trials, 2000-8

Peer reviewedPublisher PD

Food assistance is associated with improved body mass index, food security and attendance at clinic in an HIV program in central Haiti: a prospective observational cohort study

<p>Abstract</p> <p>Background</p> <p>Few data are available to guide programmatic solutions to the overlapping problems of undernutrition and HIV infection. We evaluated the impact of food assistance on patient outcomes in a comprehensive HIV program in central Haiti in a prospective observational cohort study.</p> <p>Methods</p> <p>Adults with HIV infection were eligible for monthly food rations if they had any one of: tuberculosis, body mass index (BMI) <18.5kg/m², CD4 cell count <350/mm³(in the prior 3 months) or severe socio-economic conditions. A total of 600 individuals (300 eligible and 300 ineligible for food assistance) were interviewed before rations were distributed, at 6 months and at 12 months. Data collected included demographics, BMI and food insecurity score (range 0 - 20).</p> <p>Results</p> <p>At 6- and 12-month time-points, 488 and 340 subjects were eligible for analysis. Multivariable analysis demonstrated that at 6 months, food security significantly improved in those who received food assistance versus who did not (-3.55 vs -0.16; P < 0.0001); BMI decreased significantly less in the food assistance group than in the non-food group (-0.20 vs -0.66; P = 0.020). At 12 months, food assistance was associated with improved food security (-3.49 vs -1.89, P = 0.011) and BMI (0.22 vs -0.67, P = 0.036). Food assistance was associated with improved adherence to monthly clinic visits at both 6 (P < 0.001) and 12 months (P = 0.033).</p> <p>Conclusions</p> <p>Food assistance was associated with improved food security, increased BMI, and improved adherence to clinic visits at 6 and 12 months among people living with HIV in Haiti and should be part of routine care where HIV and food insecurity overlap.</p

Revitalising audit and feedback to improve patient care

Healthcare systems face challenges in tackling variations in patient care and outcomes. Audit and feedback aim to improve patient care by reviewing clinical performance against explicit standards and directing action towards areas not meeting those standards. It is a widely used foundational component of quality improvement, included in around 60 national clinical audit programmes in the United Kingdom. Ironically, there is currently a gap between what audit and feedback can achieve and what they actually deliver, whether led locally or nationally. Several national audits have been successful in driving improvement and reducing variations in care, such as for stroke and lung cancer, but progress is also slower than hoped for in other aspects of care (table 1). Audit and feedback have a chequered past.6 Clinicians might feel threatened rather than supported by top-down feedback and rightly question whether rewards outweigh efforts invested in poorly designed audit. Healthcare organisations have limited resources to support and act on audit and feedback. Dysfunctional clinical and managerial relationships undermine effective responses to feedback, particularly when it is not clearly part of an integrated approach to quality assurance and improvement. Unsurprisingly, the full potential of audit and feedback has not been realised

The role of digital health for post-surgery care of older patients with hip fracture: A scoping review

Background: Digital health interventions can potentially improve the integration of the health care systems. Hip fracture is a serious injury for older people and integrated post-surgery care is vital for good recovery. Objective: We aimed to characterise digital health interventions used for hip fracture post-surgery care, and further to examine the extent to which of these interventions address the World Health Organisation (WHO) integrated care for older people (ICOPE) framework. Methods: A scoping review was conducted, by searching the literature from English and Chinese databases and trial registries. Keywords included hip fracture, post-surgery care and digital health interventions. Interventional, observational, qualitative studies and case reports were included. We used a combined framework, WHO ICOPE and WHO digital health intervention classifications, to support data synthesis. Results: A total of 4,542 articles were identified, of which 39 studies were included in the analysis. We identified only six randomised controlled trials. Digital health interventions were mainly used to help doctors provide clinical care and facilitate service delivery between the patients and healthcare providers. No studies focused on health workforce, financial policy or the development of infrastructure. The primary users were healthcare providers and patients, without healthcare managers or the use of data services. Most digital health interventions focused on physical therapy, bone protection and falls prevention. Limited interventions were implemented in low-and middle-income countries. Conclusion: A stronger evidence base is needed to expand the use of digital health for post-surgery care of hip fracture patients, including high-quality larger-scale studies, more focus in resource-constrained settings, expanding to more users and capabilities of interventions, and exploring the role of digital health for the integrated care model to mitigate health system challenges

Use of caffeinated substances and risk of crashes in long distance drivers of commercial vehicles: case-control study

Objective: To determine whether there is an association between use of substances that contain caffeine and the risk of crash in long distance commercial vehicle drivers.Design: Case-control studySetting: New South Wales (NSW) and Western Australia (WA), Australia.Participants: 530 long distance drivers of commercial vehicles who were recently involved in a crash attended by police (cases) and 517 control drivers who had not had a crash while driving a commercial vehicle in the past 12 months.Main outcome measure: The likelihood of a crash associated with the use of substances containing caffeine after adjustment for factors including age, health disorders, sleep patterns, and symptoms of sleep disorders as well as exposures such as kilometres driven, hours slept, breaks taken, and night driving schedules.Results: Forty three percent of drivers reported consuming substances containing caffeine, such as tea, coffee, caffeine tablets, or energy drinks for the express purpose of staying awake. Only 3% reported using illegal stimulants such as amphetamine (“speed”); 3,4 methylenedioxymethamphetamine (ecstasy); and cocaine. After adjustment for potential confounders, drivers who consumed caffeinated substances for this purpose had a 63% reduced likelihood of crashing (odds ratio 0.37, 95% confidence interval 0.27 to 0.50) compared with drivers who did not take caffeinated substances.Conclusions: Caffeinated substances are associated with a reduced risk of crashing for long distance commercial motor vehicle drivers. While comprehensive mandated strategies for fatigue management remain a priority, the use of caffeinated substances could be a useful adjunct strategy in the maintenance of alertness while driving