1,118 research outputs found

    Disentangling the Spatiotemporal Structure of Turbulence Using Multi-Spacecraft Data

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    This white paper prepared for the 2024 Decadal Survey for Solar and Space Physics concerns the importance of research related to multi-spacecraft missions to address fundamental questions concerning plasma turbulence. In this white paper, some of the important questions facing the turbulence community that can only be addressed by funding research related to multipoint measurements are presented

    Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 White Paper Plasma turbulence: Challenges and next transformative steps from the perspective of multi-spacecraft measurements

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    Synopsis We recommend to bring into reality the following within the next decade: 1. Measurements from multiple spacecraft covering a 3D volume and simultaneously spanning the MHD to kinetic scales (such as HelioSwarm). 2. Coordination of the new multi-scale mission(s) with existing multi-spacecraft missions such as MMS to maximize the power of cross-scale ion and electron measurements

    HelioSwarm: A Multipoint, Multiscale Mission to Characterize Turbulence

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    HelioSwarm (HS), a NASA MidEx multispacecraft observatory with inter-spacecraft separations covering MHD and ion scales, will measurement the structure and dynamics of magnetized turbulence. This paper surveys turbulent systems that constitute compelling areas of heliophysics research and describes how HS will measure energy transport across scales in turbulent plasmas throughout the universe

    Small Platforms, High Return: The Need to Enhance Investment in Small Satellites for Focused Science, Career Development, and Improved Equity

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    In the next decade, there is an opportunity for very high return on investment of relatively small budgets by elevating the priority of smallsat funding in heliophysics. We've learned in the past decade that these missions perform exceptionally well by traditional metrics, e.g., papers/year/\$M (Spence et al. 2022 -- arXiv:2206.02968). It is also well established that there is a "leaky pipeline" resulting in too little diversity in leadership positions (see the National Academies Report at https://www.nationalacademies.org/our-work/increasing-diversity-in-the-leadership-of-competed-space-missions). Prioritizing smallsat funding would significantly increase the number of opportunities for new leaders to learn -- a crucial patch for the pipeline and an essential phase of career development. At present, however, there are far more proposers than the available funding can support, leading to selection ratios that can be as low as 6% -- in the bottom 0.5th percentile of selection ratios across the history of ROSES. Prioritizing SmallSat funding and substantially increasing that selection ratio are the fundamental recommendations being made by this white paper.Comment: White paper submitted to the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033; 6 pages, 1 figur

    Conical shell illumination incorporating a moving aperture for depth-resolved high-energy X-ray diffraction

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    In many applications, the main limitation of X-ray absorption methods is that the signals measured are a function of the attenuation coefficient, which tells us almost nothing about the chemical or crystallographic nature of objects under inspection. To calculate fundamental crystallographic parameters requires the measurement of diffracted photons from a sample. Standard laboratory diffraction methods have been refined for well over a century and provide ‘gold standard’ structural models for well-prepared samples and single crystals but have little applicability for thick heterogeneous samples as demanded by many screening applications. We present a new high-energy X-ray diffraction probe, which in comparison with previous depth-resolving hollow beam techniques, requires a single beam, point detector and a simple swept aperture to resolve sample signatures at unknown locations within an inspection space. We perform Monte Carlo simulations to support experiments on both single- and multiple-material localisation and identification. The new probe is configured and tested using low-cost commercial components to provide a rapid and cost-effective solution for applications including explosives detection, process control and diagnostics.The Royal Society and The Wolfson Foundation RSWF\R1\180012. The Department of Homeland Security (DHS), Science and Technology Directorate, Homeland Security Advanced Research Projects Agency, Explosives Division through the Advanced X-ray Material Discrimination Program (HSHQDC-15-CB0036). Engineering and Physical Sciences Research Council: EP/T034238/1

    A broad-spectrum macrocyclic peptide inhibitor of the SARS-CoV-2 spike protein

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    The ongoing COVID-19 pandemic has had great societal and health consequences. Despite the availability of vaccines, infection rates remain high due to immune evasive Omicron sublineages. Broad-spectrum antivirals are needed to safeguard against emerging variants and future pandemics. We used messenger RNA (mRNA) display under a reprogrammed genetic code to find a spike-targeting macrocyclic peptide that inhibits SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) Wuhan strain infection and pseudoviruses containing spike proteins of SARS-CoV-2 variants or related sarbecoviruses. Structural and bioinformatic analyses reveal a conserved binding pocket between the receptor-binding domain, N-terminal domain, and S2 region, distal to the angiotensin-converting enzyme 2 receptor-interaction site. Our data reveal a hitherto unexplored site of vulnerability in sarbecoviruses that peptides and potentially other drug-like molecules can target

    Hypotension-Avoidance Versus Hypertension-Avoidance Strategies in Noncardiac Surgery: An International Randomized Controlled Trial

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    BACKGROUND: Among patients having noncardiac surgery, perioperative hemodynamic abnormalities are associated with vascular complications. Uncertainty remains about what intraoperative blood pressure to target and how to manage long-term antihypertensive medications perioperatively. OBJECTIVE: To compare the effects of a hypotension-avoidance and a hypertension-avoidance strategy on major vascular complications after noncardiac surgery. DESIGN: Partial factorial randomized trial of 2 perioperative blood pressure management strategies (reported here) and tranexamic acid versus placebo. (ClinicalTrials.gov: NCT03505723). SETTING: 110 hospitals in 22 countries. PATIENTS: 7490 patients having noncardiac surgery who were at risk for vascular complications and were receiving 1 or more long-term antihypertensive medications. INTERVENTION: In the hypotension-avoidance strategy group, the intraoperative mean arterial pressure target was 80 mm Hg or greater; before and for 2 days after surgery, renin-angiotensin-aldosterone system inhibitors were withheld and the other long-term antihypertensive medications were administered only for systolic blood pressures 130 mm Hg or greater, following an algorithm. In the hypertension-avoidance strategy group, the intraoperative mean arterial pressure target was 60 mm Hg or greater; all antihypertensive medications were continued before and after surgery. MEASUREMENTS: The primary outcome was a composite of vascular death and nonfatal myocardial injury after noncardiac surgery, stroke, and cardiac arrest at 30 days. Outcome adjudicators were masked to treatment assignment. RESULTS: The primary outcome occurred in 520 of 3742 patients (13.9%) in the hypotension-avoidance group and in 524 of 3748 patients (14.0%) in the hypertension-avoidance group (hazard ratio, 0.99 [95% CI, 0.88 to 1.12]; P = 0.92). Results were consistent for patients who used 1 or more than 1 antihypertensive medication in the long term. LIMITATION: Adherence to the assigned strategies was suboptimal; however, results were consistent across different adherence levels. CONCLUSION: In patients having noncardiac surgery, our hypotension-avoidance and hypertension-avoidance strategies resulted in a similar incidence of major vascular complications. PRIMARY FUNDING SOURCE: Canadian Institutes of Health Research, National Health and Medical Research Council (Australia), and Research Grant Council of Hong Kong

    An Update on Anti-thrombotic Therapy Following Transcatheter Aortic Valve Implantation: Expert Cardiologist Opinion from a UK and Ireland Delphi Group

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    Transcatheter aortic valve implantation (TAVI) is an effective and established treatment for symptomatic aortic stenosis. However, there is a lack of consensus concerning the need for peri- and post-procedural anti-thrombotic medication. Contemporary guidelines recommend that anti-thrombotic therapy is balanced against a patient’s bleeding risk following TAVI, but do not fully consider the evolving evidence base. The purpose of the Delphi panel recommendations presented here is to provide a consensus elicited from a panel of experts who regularly prescribe anti-thrombotic therapy post-TAVI. The goal was to address evidence gaps across four key topics: anti-thrombotic therapy (anti-platelet and/or anti-coagulant) in TAVI patients in sinus rhythm; anti-thrombotic therapy in TAVI patients with AF; direct oral anti-coagulants versus vitamin K antagonists; and the need for UK/Ireland specific guidance. This consensus statement aims to inform clinical decision-making by providing a concise, evidence-based summary of best practice for prescribing anti-thrombotic therapies following TAVI and highlights areas where further research is needed
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