A Global Preconditioning Method for the Euler Equations

This study seeks to validate a recently introduced global preconditioning technique for the Euler equations. Energy and enthalpy equations are nondimensionalized by means of a reference enthalpy, resulting in increased numerical accuracy for low-speed flows. A cellbased, finite volume formulation is used, with Roe flux difference splitting and both explicit and implicit time integration schemes. A Newton-linearized iterative implicit algorithm is implemented, with Symmetric Gauss-Seidel (LU/SGS) nested sub-iterations. This choice allows one to retain time accuracy, and eliminates approximate factorization errors, which become dominant at low speed flows. The linearized flux Jacobians are evaluated by numerical differentiation. Higher-order discretization is constructed by means of the MUSCL approach. Locally one-dimensional characteristic variable boundary conditions are implemented at the farfield boundary. The preconditioned scheme is successfully applied to the following traditional test cases used as benchmarks for local preconditioning techniques: point disturbance, flow angle disturbance, and stagnation point arising from the impingement of two identical jets. The flow over a symmetric airfoil and a convergentdivergent nozzle are then simulated for arbitrary Mach numbers. The preconditioned scheme greatly enhances accuracy and convergence rate for low-speed flows (all the way down to M ≈ 10E − 4). Some preliminary tests of fully unsteady flows are also conducted

Baseline clinical characteristics and patient profile of the TURKMI registry: Results of a nation-wide acute myocardial infarction registry in Turkey

Objective: The TURKMI registry is designed to provide insight into the characteristics, management from symptom onset to hospital discharge, and outcome of patients with acute myocardial infarction (MI) in Turkey. We report the baseline and clinical characteristics of the TURKMI population. Methods: The TURKMI study is a nation-wide registry that was conducted in 50 centers capable of percutaneous coronary intervention selected from each EuroStat NUTS region in Turkey according to population sampling weight, prioritized by the number of hospitals in each region. All consecutive patients with acute MI admitted to coronary care units within 48 hours of symptom onset were prospectively enrolled during a predefined 2-week period between November 1, 2018 and November 16, 2018. Results: A total of 1930 consecutive patients (mean age, 62.0±13.2 years; 26.1% female) with a diagnosis of acute MI were prospectively enrolled. More than half of the patients were diagnosed with non-ST elevation MI (61.9%), and 38.1% were diagnosed with ST elevation MI. Coronary angiography was performed in 93.7% and, percutaneous coronary intervention was performed in 73.2% of the study population. Fibrinolytic therapy was administered to 13 patients (0.018%). Aspirin was prescribed in 99.3% of the patients, and 94% were on dual antiplatelet therapy at the time of discharge. Beta blockers were prescribed in 85.0%, anti-lipid drugs in 96.3%, angiotensin converting enzyme inhibitors in 58.4%, and angiotensin receptor blockers in 7.9%. Comparison with European countries revealed that TURKMI patients experienced MI at younger ages compared with patients in France, Switzerland, and the United Kingdom. The most prevalent risk factors in the TURKMI population were hypercholesterolemia (60.2%), hypertension (49.5%), smoking (48.8%), and diabetes (37.9%). Conclusion: The nation-wide TURKMI registry revealed that hypercholesterolemia, hypertension, and smoking were the most prevalent risk factors. TURKMI patients were younger compared with patients in European Countries. The TURKMI registry also confirmed that current treatment guidelines are largely adopted into clinical cardiology practice in Turkey in terms of antiplatelet, anti-ischemic, and anti-lipid therapy. ©Copyright 2020 by Turkish Society of Cardiolog