A Closure for Isotropic Turbulence Based on Extended Scale Similarity Theory in Physical Space

The closure of a turbulence field is a longstanding fundamental problem, while most closure models are introduced in spectral space. Inspired by Chou＇s quasi-normal closure method in spectral space, we propose an analytical closure model for isotropic turbulence based on the extended scale similarity theory of the velocity structure function in physical space. The assumptions and certain approximations are justified with direct numerical simulation. The asymptotic scaling properties are reproduced by this new closure method, in comparison to the classical Batchelor model.

Comparison of the predictive value of the Helsinki,Rotterdam,and Stockholm CT scores in predicting 6-month outcomes in patients with blunt traumatic brain injuries

Purpose:Despite advances in modern medicine,traumatic brain injuries(TBIs)are still a major medical problem.Early diagnosis of TBI is crucial for clinical decision-making and prognosis.This study aims to compare the predictive value of Helsinki,Rotterdam,and Stockholm CT scores in predicting the 6-month outcomes in blunt TBI patients.Methods:This cohort study was conducted on blunt TBI patients of 15 years or older.All of them were admitted to the surgical emergency department of Shahid Beheshti Hospital in Kashan,Iran from 2020 to 2021 and had abnormal trauma-related findings on brain CT images.The patients’demographic data such as age,gender,history of comorbid conditions,mechanism of trauma,Glasgow coma scale,CT images,length of hospital stay,and surgical procedures were recorded.The Helsinki,Rotterdam,and Stockholm CT scores were simultaneously determined according to the existing guidelines.The included patients'6-month outcome was determined using the Glasgow outcome scale extended.M Data were analyzed by SPSS software version 16.0.Sensitivity,specificity,negative/positive predictive value and the area under the receiver operating characteristic curve were calculated for each test.The Kappa agreement coefficient and Kuder Richardson-20 were used to compare the scoring systems.Results:Altogether 171 TBI patients met the inclusion and exclusion criteria,with the mean age of(44.9±20.2)years.Most patients were male(80.7%),had traffic related injuries(83.1%)and mild TBIs(64.3%).Patients with lower Glasgow coma scale had higher Helsinki,Rotterdam,and Stockholm CT scores and lower Glasgow outcome scale extended scores.Among all the scoring systems,the Helsinki and Stockholm scores showed the highest agreement in predicting patients’outcomes(kappa=0.657,p<0.001).The Rotterdam scoring system had the highest sensitivity(90.1%)in predicting death of TBI patients,whereas the Helsinki scoring system had the highest sensitivity(89.8%)in predicting the 6-month outcome in TBI patients.Conclusion:The Rotterdam scoring system was superior in predicting death in TBI patients,whereas the Helsinki scoring system was more sensitive in predicting the 6-month outcome.