Underwater vs conventional endoscopic mucosal resection in treatment of colorectal polyps:A meta-analysis

BACKGROUND Underwater endoscopic mucosal resection(UEMR)of colorectal lesions is emerging as an alternative method to conventional endoscopic mucosal resection(EMR);however,it is still controversial whether there is a difference in the effectiveness between UEMR and EMR.AIM To evaluate the effectiveness and safety of UEMR in the treatment of colorectal polyps.METHODS Clinical studies comparing the effectiveness or safety of UEMR in the treatment of colorectal polyps were searched in medical databases,including Pub Med,Embase,Cochrane Library,CNKI,and Wanfang Data,monographs,theses,and papers presented at conferences.Statistical analyses were performed using Revman 5.3 software.RESULTS Seven non-randomized controlled trials and one randomized controlled trial met the inclusion criteria.In total,1382 patients(1511 polyps)were included in the study,including 722 who received UEMR and 789 who received EMR.In the UEMR and EMR groups,the en bloc resection rates were 85.87%and 73.89%,respectively,with a relative risk(RR)value of 1.14(95%confidence interval[CI]:1.01-1.30;P<0.05).In the sub-group analysis,the en bloc resection rate showed no statistically significant difference between the EMR and UEMR groups for polyps less than 20 mm in diameter.However,a statistically significant difference was found between the EMR and UEMR groups for polyps equal to or greater than 20 mm in diameter.The post-endoscopic resection recurrence rates at 3-6 mo of the UEMR and EMR groups were 3.26%and 15.17%,respectively,with an RR value of 0.27(95%CI:0.09-0.83;P<0.05).The post-endoscopic resection recurrence rates of UEMR and EMR at 12 mo were 6.25%and 14.40%,respectively,with an RR value of 0.43(95%CI:0.20-0.92;P<0.05).Additionally,the incidence of adverse events was 8.17%and 6.21%,respectively,with an RR value of 1.07(95%CI:0.50-2.30;P>0.05).CONCLUSION UEMR is an effective technique for colorectal polyps and appears to have some advantages over EMR,particularly with regard to some treatment outcomes.

面向控制的空天飞行器低速段动力学建模及性能折衷分析（英文）

目的:水平起降空天飞行器需兼顾高速巡航和低速起降性能。本文旨在构建一种面向控制的空天飞行器低速段动力学建模与迭代分析流程,探究质心位置对空天飞行器稳定性及控制性能的影响,并在保证空天飞行器水平起降能力的约束下,迭代获得合理的飞行器质心位置。创新点:1.结合几何外形参数化方法、势流理论和0维混合排气涡扇发动机建模方法实现空天飞行器低速段气动/推进性能数据的快速获取;2.基于所获得的气动/推进性能数据,开展代理建模研究,获得适用于性能分析及控制器设计需要的气动力/力矩系数代理模型;3.基于可变质心的气动力/力矩系数代理模型进行空天飞行器水平起降性能分析及质心位置迭代设计。方法:1.通过形状/类型函数法建立空天飞行器几何参数化模型;2.基于势流理论和0维涡扇发动机理论快速获取空天飞行器低速段气动/推进性能数据;3.通过代理模型技术,获得不同质心位置下的飞行器气动力/力矩系数拟合表达式,并基于该表达式确定符合水平起降约束的质心位置。结论:1.空天飞行器研究中,需综合考虑高低速性能,并协调水平起降、稳定性和控制性能等多方面指标;2.本文所提出的空天飞行器概念方案,满足抬头、触地约束的质心范围在距机头65%机身长度处;3.本文所提出的面向控制建模与性能分析流程可以满足空天飞行器概念方案阶段数据快速获取、方案快速迭代优化的要求。