Large-Eddy Simulations of Magnetohydrodynamic Turbulence in Heliophysics and Astrophysics

We live in an age in which high-performance computing is transforming the way we do science. Previously intractable problems are now becoming accessible by means of increasingly realistic numerical simulations. One of the most enduring and most challenging of these problems is turbulence. Yet, despite these advances, the extreme parameter regimes encountered in space physics and astrophysics (as in atmospheric and oceanic physics) still preclude direct numerical simulation. Numerical models must take a Large Eddy Simulation (LES) approach, explicitly computing only a fraction of the active dynamical scales. The success of such an approach hinges on how well the model can represent the subgrid-scales (SGS) that are not explicitly resolved. In addition to the parameter regime, heliophysical and astrophysical applications must also face an equally daunting challenge: magnetism. The presence of magnetic fields in a turbulent, electrically conducting fluid flow can dramatically alter the coupling between large and small scales, with potentially profound implications for LES/SGS modeling. In this review article, we summarize the state of the art in LES modeling of turbulent magnetohydrodynamic (MHD) ows. After discussing the nature of MHD turbulence and the small-scale processes that give rise to energy dissipation, plasma heating, and magnetic reconnection, we consider how these processes may best be captured within an LES/SGS framework. We then consider several special applications in heliophysics and astrophysics, assessing triumphs, challenges,and future directions

BIOPOLE: biogeochemical processes and ecosystem functioning in changing polar systems and their global impacts

The export of elements (particularly carbon, nitrogen and phosphorus) from the Poles critically supports global marine biodiversity and major fisheries as well as the sequestration of atmospheric carbon to the deep ocean. Ecosystem processes regulate this export, but major uncertainties remain in terms of how and by how much. Progress on understanding key ecosystem interactions is hindered by lack of data and their representation in Earth system models is poor. The two polar regions share similarities in environmental extremes which make them sensitive to the impacts of climate change. They both receive nutrients from multiple and diverse sources and the delivery of these nutrients to other oceans is regulated by similar ecosystem processes. However, the extent to which these ecosystem processes will be modified by climate change is unclear and urgently needs to be determined. BIOPOLE will determine how polar ecosystems regulate the balance of carbon and nutrients in the world’s oceans and, through it, their effect on global fish stocks and carbon storage. It will address this challenge by integrating ambitious fieldwork campaigns and innovative modelling in a multidisciplinary and highly coordinated approach. BIOPOLE will capitalise on world-leading capabilities and infrastructure in ocean and high-latitude research, including cutting-edge land-based facilities, state-of-the-art polar research vessels and innovative autonomous instrumentation. Collaboration with national and international partners will further strengthen BIOPOLE’s multidisciplinary approach and efficient use of infrastructure. BIOPOLE’s legacy will be the first assessment of the global impact of polar ecosystems on biogeochemical cycling and fish stocks; technologically-novel approaches and strong partnerships between leading international science groups

Dimethyl fumarate in patients admitted to hospital with COVID-19 (RECOVERY): a randomised, controlled, open-label, platform trial

Dimethyl fumarate (DMF) inhibits inflammasome-mediated inflammation and has been proposed as a treatment for patients hospitalised with COVID-19. This randomised, controlled, open-label platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]), is assessing multiple treatments in patients hospitalised for COVID-19 (NCT04381936, ISRCTN50189673). In this assessment of DMF performed at 27 UK hospitals, adults were randomly allocated (1:1) to either usual standard of care alone or usual standard of care plus DMF. The primary outcome was clinical status on day 5 measured on a seven-point ordinal scale. Secondary outcomes were time to sustained improvement in clinical status, time to discharge, day 5 peripheral blood oxygenation, day 5 C-reactive protein, and improvement in day 10 clinical status. Between 2 March 2021 and 18 November 2021, 713 patients were enroled in the DMF evaluation, of whom 356 were randomly allocated to receive usual care plus DMF, and 357 to usual care alone. 95% of patients received corticosteroids as part of routine care. There was no evidence of a beneficial effect of DMF on clinical status at day 5 (common odds ratio of unfavourable outcome 1.12; 95% CI 0.86-1.47; p = 0.40). There was no significant effect of DMF on any secondary outcome