Cardiac Screening of Young Athletes: a Practical Approach to Sudden Cardiac Death Prevention.

PURPOSE OF REVIEW: We aim to report on the current status of cardiovascular screening of athletes worldwide and review the up-to-date evidence for its efficacy in reducing sudden cardiac death in young athletes. RECENT FINDINGS: A large proportion of sudden cardiac death in young individuals and athletes occurs during rest with sudden arrhythmic death syndrome being recognised as the leading cause. The international recommendations for ECG interpretation have reduced the false-positive ECG rate to 3% and reduced the cost of screening by 25% without compromising the sensitivity to identify serious disease. There are some quality control issues that have been recently identified including the necessity for further training to guide physicians involved in screening young athletes. Improvements in our understanding of young sudden cardiac death and ECG interpretation guideline modification to further differentiate physiological ECG patterns from those that may represent underlying disease have significantly improved the efficacy of screening to levels that may make screening more attractive and feasible to sporting organisations as a complementary strategy to increased availability of automated external defibrillators to reduce the overall burden of young sudden cardiac death

Inhibition of E2-induced expression of BRCA1 by persistent organochlorines

BACKGROUND: Environmental persistent organochlorines (POCs) biomagnify in the food chain, and the chemicals are suspected of being involved in a broad range of human malignancies. It is speculated that some POCs that can interfere with estrogen receptor-mediated responses are involved in the initiation and progression of human breast cancer. The tumor suppressor gene BRCA1 plays a role in cell-cycle control, in DNA repair, and in genomic stability, and it is often downregulated in sporadic mammary cancers. The aim of the present study was to elucidate whether POCs have the potential to alter the expression of BRCA1. METHODS: Using human breast cancer cell lines MCF-7 and MDA-MB-231, the effect on BRCA1 expression of chemicals belonging to different classes of organochlorine chemicals (the pesticide toxaphene, 2,3,7,8-tetrachlorodibenzo-p-dioxin, and three polychlorinated biphenyls [PCB#138, PCB#153 and PCB#180]) was measured by a reporter gene construct carrying 267 bp of the BRCA1 promoter. A twofold concentration range was analyzed in MCF-7, and the results were supported by northern blot analysis of BRCA1 mRNA using the highest concentrations of the chemicals. RESULTS: All three polychlorinated biphenyls and 2,3,7,8-tetrachlorodibenzo-p-dioxin reduced 17β-estradiol (E2)-induced expression as well as basal reporter gene expression in both cell lines, whereas northern blot analysis only revealed a downregulation of E2-induced BRCA1 mRNA expression in MCF-7 cells. Toxaphene, like E2, induced BRCA1 expression in MCF-7. CONCLUSION: The present study shows that some POCs have the capability to alter the expression of the tumor suppressor gene BRCA1 without affecting the cell-cycle control protein p21(Waf/Cip1). Some POCs therefore have the potential to affect breast cancer risk

Identifying causes of Western Pacific ITCZ drift in ECMWF System 4 hindcasts

The development of systematic biases in climate models used in operational seasonal forecasting adversely affects the quality of forecasts they produce. In this study, we examine the initial evolution of systematic biases in the ECMWF System 4 forecast model, and isolate aspects of the model simulations that lead to the development of these biases. We focus on the tendency of the simulated intertropical convergence zone in the western equatorial Pacific to drift northwards by between 0.5° and 3° of latitude depending on season. Comparing observations with both fully coupled atmosphere–ocean hindcasts and atmosphere-only hindcasts (driven by observed sea-surface temperatures), we show that the northward drift is caused by a cooling of the sea-surface temperature on the Equator. The cooling is associated with anomalous easterly wind stress and excessive evaporation during the first twenty days of hindcast, both of which occur whether air-sea interactions are permitted or not. The easterly wind bias develops immediately after initialisation throughout the lower troposphere; a westerly bias develops in the upper troposphere after about ten days of hindcast. At this point, the baroclinic structure of the wind bias suggests coupling with errors in convective heating, although the initial wind bias is barotropic in structure and appears to have an alternative origin

Globalization and Health: developing the journal to advance the field

Founded in 2005, Globalization and Health was the first open access global health journal. The journal has since expanded the field, and its influence, with the number of downloaded papers rising 17-fold, to over 4 million. Its ground-breaking papers, leading authors -including a Nobel Prize winner- and an impact factor of 2.25 place it among the top global health journals in the world. To mark the ten years since the journal’s founding, we, members of the current editorial board, undertook a review of the journal’s progress over the last decade. Through the application of an inductive thematic analysis, we systematically identified themes of research published in the journal from 2005 to 2014. We identify key areas the journal has promoted and consider these in the context of an existing framework, identify current gaps in global health research and highlight areas we, as a journal, would like to see strengthened

A local Fourier analysis of additive Vanka relaxation for the Stokes equations

Multigrid methods are popular solution algorithms for many discretized PDEs, either as standalone iterative solvers or as preconditioners, due to their high efficiency. However, the choice and optimization of multigrid components such as relaxation schemes and grid-transfer operators is crucial to the design of optimally efficient algorithms. It is well–known that local Fourier analysis (LFA) is a useful tool to predict and analyze the performance of these components. In this paper, we develop a local Fourier analysis of monolithic multigrid methods based on additive Vanka relaxation schemes for mixed finite-element discretizations of the Stokes equations. The analysis offers insight into the choice of “patches” for the Vanka relaxation, revealing that smaller patches offer more effective convergence per floating point operation. Parameters that minimize the two-grid convergence factor are proposed and numerical experiments are presented to validate the LFA predictions

Combining deflation and nested iteration for computing multiple solutions of nonlinear variational problems

Many physical systems support multiple equilibrium states that enable their use in modern science and engineering applications. Having the ability to reliably compute such states facilitates more accurate physical analysis and understanding of experimental behavior. This paper adapts and extends a deflation technique for the computation of multiple distinct solutions in the context of nonlinear systems and applies the method to the modeling of equilibrium configurations of nematic and cholesteric liquid crystals. In particular, the deflation approach is interwoven with nested iteration, creating an efficient and effective method that further enables the discovery of distinct solutions. The combined methodology is applied as part of an overall free-energy variational approach within the framework of optimization of a functional with constraints imposed via Lagrange multipliers. A key feature in the combined algorithm is the reuse of effective preconditioners designed for the undeflated systems within the Newton iteration for the deflated systems. Four numerical experiments are performed, demonstrating the efficacy and accuracy of the algorithm in detecting important physical phenomena, including bifurcation and disclination behaviors

Combining deflation and nested iteration for computing multiple solutions of nonlinear variational problems

Many physical systems support multiple equilibrium states that enable their use in modern science and engineering applications. Having the ability to reliably compute such states facilitates more accurate physical analysis and understanding of experimental behavior. This paper adapts and extends a deflation technique for the computation of multiple distinct solutions in the context of nonlinear systems and applies the method to the modeling of equilibrium configurations of nematic and cholesteric liquid crystals. In particular, the deflation approach is interwoven with nested iteration, creating an efficient and effective method that further enables the discovery of distinct solutions. The combined methodology is applied as part of an overall free-energy variational approach within the framework of optimization of a functional with constraints imposed via Lagrange multipliers. A key feature in the combined algorithm is the reuse of effective preconditioners designed for the undeflated systems within the Newton iteration for the deflated systems. Four numerical experiments are performed, demonstrating the efficacy and accuracy of the algorithm in detecting important physical phenomena, including bifurcation and disclination behaviors

Multigrid methods with space-time concurrency

We consider the comparison of multigrid methods for parabolic partial differential equations that allow space–time concurrency. With current trends in computer architectures leading towards systems with more, but not faster, processors, space–time concurrency is crucial for speeding up time-integration simulations. In contrast, traditional time-integration techniques impose serious limitations on parallel performance due to the sequential nature of the time-stepping approach, allowing spatial concurrency only. This paper considers the three basic options of multigrid algorithms on space–time grids that allow parallelism in space and time: coarsening in space and time, semicoarsening in the spatial dimensions, and semicoarsening in the temporal dimension. We develop parallel software and performance models to study the three methods at scales of up to 16K cores and introduce an extension of one of them for handling multistep time integration.We then discuss advantages and disadvantages of the different approaches and their benefit compared to traditional space-parallel algorithms with sequential time stepping on modern architectures.status: publishe