Troubled-Cell Indicator Based on Mean Value Property for Hybrid WENO Schemes

In this paper, we introduce a new type of troubled-cell indicator to improve hybrid weighted essentially non-oscillatory (WENO) schemes for solving the hyperbolic conservation laws. The hybrid WENO schemes selectively adopt the high-order linear upwind scheme or the WENO scheme to avoid the local characteristic decompositions and calculations of the nonlinear weights in smooth regions. Therefore, they can reduce computational cost while maintaining non-oscillatory properties in non-smooth regions. Reliable troubled-cell indicators are essential for efficient hybrid WENO methods. Most of troubled-cell indicators require proper parameters to detect discontinuities precisely, but it is very difficult to determine the parameters automatically. We develop a new troubled-cell indicator derived from the mean value theorem that does not require any variable parameters. Additionally, we investigate the characteristics of indicator variable; one of the conserved properties or the entropy is considered as indicator variable. Detailed numerical tests for 1D and 2D Euler equations are conducted to demonstrate the performance of the proposed indicator. The results with the proposed troubled-cell indicator are in good agreement with pure WENO schemes. Also the new indicator has advantages in the computational cost compared with the other indicators.     

Unconditional Positivity-Preserving and Energy Stable Schemes for a Reduced Poisson-Nernst-Planck System

The Poisson-Nernst-Planck (PNP) system is a widely accepted model for simulation of ionic channels. In this paper, we design, analyze, and numerically validate a second order unconditional positivity-preserving scheme for solving a reduced PNP system, which can well approximate the three dimensional ion channel problem. Positivity of numerical solutions is proven to hold true independent of the size of time steps and the choice of the Poisson solver. The scheme is easy to implement without resorting to any iteration method. Several numerical examples further confirm the positivity-preserving property, and demonstrate the accuracy, efficiency, and robustness of the proposed scheme, as well as the fast approach to steady states.     

单纯 Ilizarov 环形外固定技术治疗合并骨筋膜室综合征的胫骨平台骨折

目的探讨单纯 Ilizarov 环形外固定技术治疗合并骨筋膜室综合征的胫骨平台骨折的疗效。方法2013 年 9 月—2017 年 3 月，收治 30 例合并骨筋膜室综合征的胫骨平台骨折患者，采用单纯 Ilizarov 环形外固定技术治疗。男 23 例，女 7 例；年龄 23～43 岁，平均 34.4 岁。致伤原因：交通事故伤 12 例，高处坠落伤 4 例，摔伤 8 例，重物砸伤 6 例。受伤至入院时间 1～12 h，平均 4.8 h。骨折 Schatzker 分型：Ⅱ型 1 例、Ⅲ型 3 例、Ⅳ型 10 例、Ⅴ型 7 例、Ⅵ型 9 例。30 例均因骨筋膜室综合征行切开减压；切开减压至手术时间为 10～15 d，平均 12.5 d。治疗后采用膝关节学会评分系统（KSS）及 Ilizarov 方法研究与应用协会（ASAMI）协议评价膝关节功能。结果手术时间 110～155 min，平均 123.1 min；术中出血量 100～500 mL，平均 245 mL；术后住院时间 3～5 d，平均 3.8 d。患者均获随访，随访时间 20～24 周，平均 22.7 周。除 2 例患者出现针道感染征象外，无其他并发症发生。X 线片复查显示骨折均愈合，愈合时间 10～20 周，平均 14.6 周。末次随访时，膝关节 KSS 临床评分总分为 70～95 分，平均 87.5 分；功能评分总分为 70～90 分，平均 79.0 分。参照 ASAMI 协议评价获优 24 例、良 3 例、可 2 例、差 1 例。结论对于合并骨筋膜室综合征的胫骨平台骨折，单纯 Ilizarov 环形外固定技术治疗后患者关节功能可以基本恢复且并发症少，是一项相对安全、有效的治疗方法。     

罗伊氏乳杆菌对轮状病毒感染肠炎患儿免疫功能与肠道菌群及临床疗效的影响

目的探究罗伊氏乳杆菌DSM 17938在治疗轮状病毒感染肠炎患儿中的疗效及对免疫功能、肠道菌群的影响。方法收集于2018年2月-2019年2月在阳光融和医院进行诊治的轮状病毒感染肠炎患儿126例,随机分为试验组(63例)和对照组(63例)。对照组给予常规补液治疗及蒙脱石散和枯草杆菌二联活菌口服治疗,试验组采用常规补液治疗及蒙脱石散和罗伊氏乳杆菌DSM 17938辅助治疗。观察两组患儿的腹泻改善情况,并分析对免疫功能(IgG、IgA、CD4^+/CD8^+水平)及肠道菌群失调的影响。结果在治疗72 h后,试验组患儿的治疗总有效率为92.06%,高于对照组的74.60%(P=0.009);且治疗后两组患儿的IgG、IgA、CD4^+/CD8^+水平均较治疗前有升高(P<0.05),且试验组水平高于对照组(P<0.05)。对患儿肠道菌群进行分析,在治疗1周后,试验组患儿肠道菌群失调程度低于对照组,且试验组的肠道菌群正常比例高于对照组(P<0.05)。结论罗伊氏乳杆菌DSM 17938对于辅助治疗轮状病毒感染肠炎患儿具有良好的疗效,能够提高患儿免疫力,改善肠道菌群失调,减轻患儿腹泻症状,具有一定的临床应用价值。     

Effect of a Device-Free Compressed Shell Fixation Method on Hepatic Respiratory Movement: Analysis for Respiratory Amplitude of the Liver and Internal Motions of a Fiducial Marker

Purpose

Suppression of respiratory movement of the liver would be desirable for high-precision radiation therapy for liver tumors. We aimed to investigate the effect of our original device-free compressed shell fixation method and breathing instruction on suppression of respiratory movement. The characteristics of liver motion based on the movement of a fiducial marker were also analyzed.