Weighted decomposition in high-performance lattice-Boltzmann simulations: Are some lattice sites more equal than others?

Obtaining a good load balance is a significant challenge in scaling up lattice-Boltzmann simulations of realistic sparse problems to the exascale. Here we analyze the effect of weighted decomposition on the performance of the HemeLB lattice-Boltzmann simulation environment, when applied to sparse domains. Prior to domain decomposition, we assign wall and in/outlet sites with increased weights which reflect their increased computational cost. We combine our weighted decomposition with a second optimization, which is to sort the lattice sites according to a space filling curve. We tested these strategies on a sparse bifurcation and very sparse aneurysm geometry, and find that using weights reduces calculation load imbalance by up to 85 %, although the overall communication overhead is higher than some of our runs.This work has received funding from the CRESTA and MAPPER projects within the EC-FP7 (ICT-2011.9.13) under Grant Agreements nos. 287703 and 261507, and from EPSRC Grants EP/I017909/1 (www.2020science.net) and EP/I034602/1

Point-of-care screening for a current Hepatitis C virus infection: influence on uptake of a concomitant offer of HIV screening

Eliminating hepatitis C as a public health threat requires an improved understanding of how to increase testing uptake. We piloted point-of-care testing (POCT) for a current HCV infection in an inner-city Emergency Department (ED) and assessed the influence on uptake of offering concomitant screening for HIV. Over four months, all adults attending ED with minor injuries were first invited to complete an anonymous questionnaire then invited to test in alternating cycles offering HCV POCT or HCV+HIV POCT. Viral RNA was detected in finger-prick blood by GeneXpert. 814/859 (94.8%) questionnaires were returned and 324/814 (39.8%) tests were accepted, comprising 211 HCV tests and 113 HCV+HIV tests. Offering concomitant HIV screening reduced uptake after adjusting for age and previous HCV testing (odds ratio 0.51; 95% confidence interval [CI] 0.38–0.68; p < 0.001). HCV prevalence was 1/324 (0.31%; 95% CI 0.05–1.73); no participant tested positive for HIV. 167/297 (56.2%) POCT participants lived in the most deprived neighbourhoods in England. HCV RNA testing using finger-prick blood was technically feasible. Uptake was moderate and the offer of concomitant HIV screening showed a detrimental impact on acceptability in this low prevalence population. The findings should be confirmed in a variety of other community settings

Coalesced communication: a design pattern for complex parallel scientific software

We present a new design pattern for high-performance parallel scientific software, named coalesced communication. This pattern allows for a structured way to improve the communication performance through coalescence of multiple communication needs using two communication management components. We apply the design pattern to several simulations of a lattice-Boltzmann blood flow solver with streaming visualisation which engenders a reduction in the communication overhead of approximately 40%

Spasticity of the gastrosoleus muscle is related to the development of reduced passive dorsiflexion of the ankle in children with cerebral palsy: A registry analysis of 2,796 examinations in 355 children

Background and purpose Spasticity and muscle contracture are two common manifestations of cerebral palsy (CP). A spastic muscle may inhibit growth in length of the muscle, but the importance of this relationship is not known. In 1994, a register and a healthcare program for children with CP in southern Sweden were initiated. The child's muscle tone according to the Ashworth scale and the ankle range of motion (ROM) is measured annually during the entire growth period. We have used these data to analyze the relationship between spasticity and ROM of the gastrosoleus muscle. Patients and methods All measurements in the total population of children with CP aged 0-18 years during the period January 1995 through June 2008 were analyzed. The study was based on 2,796 examinations in 355 children. In the statistical analysis, the effect of muscle tone on ROM was estimated using a random effects model. Results The range of dorsiflexion of the ankle joint decreased in the total material by mean 19 (95% CI: 14-24) degrees during the first 18 years of life. There was a statistically significant association between the ROM and the child's level of spasticity during the year preceding the ROM measurement. Interpretation Spasticity is related to the development of muscle contracture. In the treatment of children with CP, the spasticity, contracture, and strength of the gastrosoleus muscle must be considered together

Próteses parciais fixas reforçadas por fibras: um estudo clínico retrospectivo preliminar

The aim of this study was to evaluate the clinical performance (retention rate) of fiber-reinforced composite fixed partial dentures (FPDs). Polyethylene fiber (Ribbond®) was used combined with restorative composite during FPDs fabrication. FPDs were placed in thirteen patients in a private clinic. Nineteen FPDs were evaluated. The prosthetic space was filled with only one pontic using extracted teeth (2 cases), acrylic resin teeth (11 cases), or with composite resin (6 cases), combined with Polyethylene fiber. The clinical criterion used was based on retention rate of FPDs. If FPDs were in function in the mouth at the time of examination without previous repair they were classified as Complete Survival (CS) restorations. A classification of Survival with Rebonding (SR) was assigned in the event of an adhesive failure, but after rebonding the FPD still remained under evaluation. Treatment was classified as a Failure (F) if the FPD restoration was lost. The time of evaluation was 41.15 months (±15.13). The FPDs evaluated were retained (CS=94.75%), and no failure was found except for in one situation which required rebonding (SR=5.25%). According to the survival estimation method of Kaplan-Meyer the mean survival time was 42.3 months. At the time of evaluation investigated, polyethylene-reinforced FPDs showed a favorable retention rate in preliminary data.O objetivo deste estudo foi avaliar a performance clínica (percentagem de retenção) de próteses parciais fixas reforçadas por fibras. Fibras de polietileno (Ribbond®) foram usadas em combinação com resina composta durante a confecção das próteses. Os tratamentos foram realizadas em 13 pacientes, em uma clínica privada., sendo que 19 próteses foram reavaliadas. O espaço protético era preenchido com um pôntico usando o próprio dente extraído (2 casos), dentes de acrílico (11 casos) ou confeccionados com resina composta (6 casos), em todas as situações eram empregadas fibras de polietileno. Os critérios clínicos usados foram baseados na percentagem de retenção das próteses parciais fixas. As próteses que estavam em função no momento da avaliação, sem nunca necessitar de qualquer reparo prévio, foram classificadas como sobrevivência completa (SC). A classificação de sobrevivência com nova colagem (SR) foi utilizada para os casos de falha adesiva, com posterior cimentação da peça, a qual permanecia em função. O tratamento era classificado como falha (F) quando a restauração era perdida. O tempo médio de avaliação foi de 41,15 meses (±15,13). Nenhum caso de falha foi detectado, em apenas um caso houve falha adesiva com posterior colagem da peça (SR=5,25%) e em 94.75% dos casos as próteses permaneciam em função.. De acordo com o método de sobrevida de Kaplan-Meyer o tempo médio de sobrevida foi de 42,3 meses. As próteses parciais fixas reforçadas por fibras mostraram uma percentagem de retenção favorável neste estudo preliminar

Flexible composition and execution of high performance, high fidelity multiscale biomedical simulations

Multiscale simulations are essential in the biomedical domain to accurately model human physiology. We present a modular approach for designing, constructing and executing multiscale simulations on a wide range of resources, from laptops to petascale supercomputers, including combinations of these. Our work features two multiscale applications, in-stent restenosis and cerebrovascular bloodflow, which combine multiple existing single-scale applications to create a multiscale simulation. These applications can be efficiently coupled, deployed and executed on computers up to the largest (peta) scale, incurring a coupling overhead of 1–10% of the total execution time

Nash Social Welfare in Selfish and Online Load Balancing

In load balancing problems there is a set of clients, each wishing to select a resource from a set of permissible ones, in order to execute a certain task. Each resource has a latency function, which depends on its workload, and a client's cost is the completion time of her chosen resource. Two fundamental variants of load balancing problems are {\em selfish load balancing} (aka. {\em load balancing games}), where clients are non-cooperative selfish players aimed at minimizing their own cost solely, and {\em online load balancing}, where clients appear online and have to be irrevocably assigned to a resource without any knowledge about future requests. We revisit both selfish and online load balancing under the objective of minimizing the {\em Nash Social Welfare}, i.e., the geometric mean of the clients' costs. To the best of our knowledge, despite being a celebrated welfare estimator in many social contexts, the Nash Social Welfare has not been considered so far as a benchmarking quality measure in load balancing problems. We provide tight bounds on the price of anarchy of pure Nash equilibria and on the competitive ratio of the greedy algorithm under very general latency functions, including polynomial ones. For this particular class, we also prove that the greedy strategy is optimal as it matches the performance of any possible online algorithm