Experimental and CFD analysis of the wake characteristics of tidal turbines

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.This paper investigates the accuracy of the Computational Fluid Dynamics (CFD) based Immersed Body Force (IBF) turbine modelling method for predicting the flow characteristics of a Momentum-Reversal-Lift type of tidal turbine. This empirically-based CFD model has been developed based on the actuator disc method enhanced with additional features to mimic the effect of the complex blade motion on the downstream wake, without the high computational costs of explicitly modelling the dynamic blade motion. The model has been calibrated against the flow characteristics data obtained from experiment and found to perform well, although there are few inconsistencies in the flow patterns which show some of the limitations of the IBF model compared to a full dynamic blade motion simulation. However, given the complexity and computational cost of modelling the detailed blade motion the limitations of the IBF model are acceptable and will be useful especially for optimisation of arrays of devices where there is a significant computational demand.We would like to thank EPSRC for providing the funding under project number EP/J010138/1, as part of the Supergen Marine research program and the IFREMER personnel of Boulogne-sur-Mer for their assistance and advice during the experimental trials

Refining rodent models of spinal cord injury.

This report was produced by an Expert Working Group (EWG) consisting of UK-based researchers, veterinarians and regulators of animal experiments with specialist knowledge of the use of animal models of spinal cord injury (SCI). It aims to facilitate the implementation of the Three Rs (Replacement, Reduction and Refinement), with an emphasis on refinement. Specific animal welfare issues were identified and discussed, and practical measures proposed, with the aim of reducing animal use and suffering, reducing experimental variability, and increasing translatability within this critically important research field

Disease progression in Plasmodium knowlesi malaria is linked to variation in invasion gene family members.

Emerging pathogens undermine initiatives to control the global health impact of infectious diseases. Zoonotic malaria is no exception. Plasmodium knowlesi, a malaria parasite of Southeast Asian macaques, has entered the human population. P. knowlesi, like Plasmodium falciparum, can reach high parasitaemia in human infections, and the World Health Organization guidelines for severe malaria list hyperparasitaemia among the measures of severe malaria in both infections. Not all patients with P. knowlesi infections develop hyperparasitaemia, and it is important to determine why. Between isolate variability in erythrocyte invasion, efficiency seems key. Here we investigate the idea that particular alleles of two P. knowlesi erythrocyte invasion genes, P. knowlesi normocyte binding protein Pknbpxa and Pknbpxb, influence parasitaemia and human disease progression. Pknbpxa and Pknbpxb reference DNA sequences were generated from five geographically and temporally distinct P. knowlesi patient isolates. Polymorphic regions of each gene (approximately 800 bp) were identified by haplotyping 147 patient isolates at each locus. Parasitaemia in the study cohort was associated with markers of disease severity including liver and renal dysfunction, haemoglobin, platelets and lactate, (r = ≥ 0.34, p =  <0.0001 for all). Seventy-five and 51 Pknbpxa and Pknbpxb haplotypes were resolved in 138 (94%) and 134 (92%) patient isolates respectively. The haplotypes formed twelve Pknbpxa and two Pknbpxb allelic groups. Patients infected with parasites with particular Pknbpxa and Pknbpxb alleles within the groups had significantly higher parasitaemia and other markers of disease severity. Our study strongly suggests that P. knowlesi invasion gene variants contribute to parasite virulence. We focused on two invasion genes, and we anticipate that additional virulent loci will be identified in pathogen genome-wide studies. The multiple sustained entries of this diverse pathogen into the human population must give cause for concern to malaria elimination strategists in the Southeast Asian region

Evaluation of splenic switch off in a tertiary imaging centre: validation and assessment of utility.

Aims: Adenosine can induce splenic vasoconstriction (splenic switch-off, SSO). In this study, we aim to evaluate the utility of identifying a lack of SSO for detecting false-negative adenosine stress perfusion cardiac magnetic resonance (CMR) scans. Methods and results: We visually analysed 492 adenosine stress perfusion CMR scans reported as negative in a cohort of patients with no previous history of coronary artery disease. A lack of SSO was identified in 11%. We quantified the phenomenon by drawing regions of interest on the spleen and comparing intensity between stress and rest scans, the spleen intensity ratio (SIR). Inter-rater agreement for qualitative determination of SSO was κ = 0.81 and inter-class correlation for quantitative determination of SSO was 0.94. The optimal threshold for SIR as an indicator of SSO was 0.40 (sensitivity = 82.5%, specificity = 92.3%, AUC = 0.91). 23 065 CMR scans and 9926 invasive coronary angiogram reports were retrospectively examined to identify patients with negative CMR scans who required coronary intervention in the subsequent 12 months (false negatives). We compared these scans with true positives who had positive adenosine stress perfusion CMR scans followed by coronary intervention. The rate of lack of SSO was 20.7% in the false-negative group versus 13.1% in true positives (P = 0.37). Conclusion: The lack of SSO is prevalent, easily measureable, and has potential to improve on haemodynamic criteria as a marker of adenosine understress in CMR perfusion scans.This work forms part of the research areas contributing to the translational research portfolio of the Cardiovascular Biomedical Research Unit at Barts which is supported and funded by the National Institute for Health Research. C.M. is partially funded by support from the National Institute for Health Research University College London Hospitals Biomedical Research Centre

Mechanical effects of left ventricular midwall fibrosis in non-ischemic cardiomyopathy

Background: Left ventricular (LV) mid-wall fibrosis (MWF), which occurs in about a quarter of patients with non-ischemic cardiomyopathy (NICM), is associated with high risk of pump failure. The mid LV wall is the site of circumferential myocardial fibers. We sought to determine the effect of MWF on LV myocardial mechanics. Methods: Patients with NICM (n = 116; age: 62.8 ± 13.2 years; 67 % male) underwent late gadolinium enhancement cardiovascular magnetic resonance (CMR) and were categorized according to the presence (+) or absence (-) of MWF. Feature tracking (FT) CMR was used to assess myocardial deformation. Results: Despite a similar LVEF (24.3 vs 27.5 %, p = 0.20), patients with MWF (32 [24 %]) had lower global circumferential strain (εcc: -6.6 % vs -9.4 %, P = 0.004), but similar longitudinal (εll: -7.6 % vs. -9.4 %, p = 0.053) and radial (εrr: 14.6 % vs. 17.8 % p = 0.18) strain. Compared with - MWF, + MWF was associated with reduced LV systolic, circumferential strain rate (-0.38 ± 0.1 vs -0.56 ± 0.3 s-1, p = 0.005) and peak LV twist (4.65 vs. 6.31°, p = 0.004), as well as rigid LV body rotation (64 % vs 28 %, P cc: 0.34 vs. 0.46 s-1; DSRll: 0.38 vs. 0.50s-1; DSRrr: -0.55 vs. -0.75 s-1; all

Which interventions offer best value for money in primary prevention of cardiovascular disease?

BackgroundDespite many decades of declining mortality rates in the Western world, cardiovascular disease remains the leading cause of death worldwide. In this research we evaluate the optimal mix of lifestyle, pharmaceutical and population-wide interventions for primary prevention of cardiovascular disease.Methods and FindingsIn a discrete time Markov model we simulate the ischaemic heart disease and stroke outcomes and cost impacts of intervention over the lifetime of all Australian men and women, aged 35 to 84 years, who have never experienced a heart disease or stroke event. Best value for money is achieved by mandating moderate limits on salt in the manufacture of bread, margarine and cereal. A combination of diuretic, calcium channel blocker, ACE inhibitor and low-cost statin, for everyone with at least 5% five-year risk of cardiovascular disease, is also cost-effective, but lifestyle interventions aiming to change risky dietary and exercise behaviours are extremely poor value for money and have little population health benefit.ConclusionsThere is huge potential for improving efficiency in cardiovascular disease prevention in Australia. A tougher approach from Government to mandating limits on salt in processed foods and reducing excessive statin prices, and a shift away from lifestyle counselling to more efficient absolute risk-based prescription of preventive drugs, could cut health care costs while improving population health.<br /

Scans for signatures of selection in Russian cattle breed genomes reveal new candidate genes for environmental adaptation and acclimation

Domestication and selective breeding has resulted in over 1000 extant cattle breeds. Many of these breeds do not excel in important traits but are adapted to local environments. These adaptations are a valuable source of genetic material for efforts to improve commercial breeds. As a step toward this goal we identified candidate regions to be under selection in genomes of nine Russian native cattle breeds adapted to survive in harsh climates. After comparing our data to other breeds of European and Asian origins we found known and novel candidate genes that could potentially be related to domestication, economically important traits and environmental adaptations in cattle. The Russian cattle breed genomes contained regions under putative selection with genes that may be related to adaptations to harsh environments (e.g., AQP5, RAD50, and RETREG1). We found genomic signatures of selective sweeps near key genes related to economically important traits, such as the milk production (e.g., DGAT1, ABCG2), growth (e.g., XKR4), and reproduction (e.g., CSF2). Our data point to candidate genes which should be included in future studies attempting to identify genes to improve the extant breeds and facilitate generation of commercial breeds that fit better into the environments of Russia and other countries with similar climates