This paper studies the wall-bounded flow around a cylindrical at a high Reynolds numbers body in a determined computational domain, with simulations of the 3-D, turbulent concentric annulus flow in a straight pipe. Nu...This paper studies the wall-bounded flow around a cylindrical at a high Reynolds numbers body in a determined computational domain, with simulations of the 3-D, turbulent concentric annulus flow in a straight pipe. Numerical results show that a reversing zone, appearing as a tongue zone with nested velocities higher than the surrounding area, exists behind the cylindrical body. The annulus space is a region of high velocity and low pressure. The zero velocity, of combined the X- velocity and the Y- velocity, exists in the cross sections and no vortex shedding is formed behind the attaching cylinders. Among all investigated effecting factors, the diameters of the attaching and the main cylinders affect the wake feature behind the cylindrical body while the main cylinder length does not affect the distribution tendency of the flow field. The diameters of the main cylinder and the pipe affect the pressure values and the distribution tendencies on the main cylinder surface. Obviously, the increase of the pipe diameter reduces the drag coefficient of the cylindrical body and the increase of the diameter of the main cylinder increases the drag coefficient greatly. The numerical investigation of the concentric annulus flow provides foundations for further improvements of the intricate flow studies.展开更多
目的分析新生儿肺炎(NP)患儿经加温湿化高流量鼻导管通气(HHFNC)治疗失败的危险因素,构建预测模型并评估其预测效能。方法选取2023年2月至2024年10月南阳市中心医院收治的130例NP患儿,均采用HHFNC作为主要呼吸支持治疗方式。依据HHFNC...目的分析新生儿肺炎(NP)患儿经加温湿化高流量鼻导管通气(HHFNC)治疗失败的危险因素,构建预测模型并评估其预测效能。方法选取2023年2月至2024年10月南阳市中心医院收治的130例NP患儿,均采用HHFNC作为主要呼吸支持治疗方式。依据HHFNC治疗效果分为治疗成功组、治疗失败组,单因素、多因素logistic回归分析法筛选NP患儿HHFNC治疗失败的影响因素。基于上述影响因素构建NP患儿HHFNC治疗失败风险列线图模型,并评估列线图模型预测效能。结果采用HHFNC作为主要呼吸支持治疗方式的130例NP患儿中,22例(16.92%)患儿HHFNC治疗失败,108例(83.08%)患儿HHFNC治疗成功。治疗成功组、治疗失败组咽喉分泌物清理不及时比例、出生后5 min Apgar评分、HHFNC治疗前降钙素原(PCT)、25羟维生素D(25-OH-D)、呼吸评分(RS)、氧合指数(OI)及HHFNC初始吸入氧浓度(FiO_(2))差异有统计学意义(P<0.05)。多因素logistic回归分析,结果显示,咽喉分泌物清理不及时(OR=1.352)、HHFNC治疗前PCT(OR=1.329)、HHFNC治疗前RS(OR=1.124)、HHFNC初始FiO_(2)(OR=1.042)是NP患儿HHFNC治疗失败的危险因素(P<0.05),出生后5 min Apgar评分(OR=0.742)、HHFNC治疗前25-OH-D(OR=0.710)、HHFNC治疗前OI(OR=0.804)是NP患儿HHFNC治疗失败的保护因素(P<0.05)。基于上述影响因素构建NP患儿HHFNC治疗失败风险列线图模型,结果显示,该列线图模型预测值与实测值差异无统计学意义(χ^(2)=2.025,P=0.228),预测NP患儿HHFNC治疗失败的敏感度、特异度、曲线下面积分别为90.00%、78.00%、0.889(95%CI:0.752~0.945),且当预测概率阈值0.20~0.75时,对NP患儿采取干预措施,患儿净获益情况最佳。结论NP患儿HHFNC治疗失败受咽喉分泌物清理不及时、出生后5 min Apgar评分、HHFNC治疗前PCT、25-OH-D、RS、OI及HHFNC初始FiO_(2)的影响。本研究构建的列线图模型预测NP患儿HHFNC治疗失败的准确度、区分度均较高。展开更多
目的:探讨心血管病危险因素对无或轻度冠状动脉(冠脉)狭窄的非血流受限人群的心肌血流量(MBF)及冠脉血流储备(CFR)的影响。方法:回顾性分析在本科室完成13N-氨水正电子发射计算机断层成像(PET)心肌灌注显像(MPI)、冠脉计算机断层摄影术(...目的:探讨心血管病危险因素对无或轻度冠状动脉(冠脉)狭窄的非血流受限人群的心肌血流量(MBF)及冠脉血流储备(CFR)的影响。方法:回顾性分析在本科室完成13N-氨水正电子发射计算机断层成像(PET)心肌灌注显像(MPI)、冠脉计算机断层摄影术(CT)血管造影(CTA)或冠脉造影(CAG)检查提示无或轻度冠脉狭窄的68例受检者,收集整理一般资料(包括年龄、性别、体重指数)及冠心病传统危险因素(糖尿病、高血压、血脂异常、长期吸烟、心血管病家族史)、潜在危险因素(包括阻塞性睡眠呼吸暂停综合征、肿瘤术后化疗后、甲状腺功能亢进症),经绝对定量分析获得静息及负荷MBF、左心室整体CFR。用χ~2检验、二元Logistic回归法分析上述危险因素对心肌灌注的影响。结果:单因素分析发现,男性的负荷MBF低于女性[(3.02±0.72)ml/(min·gm) vs(3.77±0.86)ml/(min·gm),χ~2=3.886,P=0.049],年龄>55岁受试者的CFR最小值(CFRmin)较≤55岁者减低(2.12±0.37 vs2.62±0.67,χ~2=10.236,P=0.001),糖尿病患者CFRmin(2.17±0.44 vs 2.51±0.65,χ~2=5.798,P=0.016)、负荷MBF[(2.79±0.64)ml/(min·gm) vs(3.57±0.86)ml/(min·gm),χ~2=7.053,P=0.008]低于无糖尿病者,存在潜在危险因素人群的CFR平均值(CFRmean)低于无潜在危险因素人群(2.42±0.44 vs 3.30±0.72,P=0.003)。多因素Logistic回归分析结果提示,糖尿病(OR=5.471,95%CI:1.040～28.788)、年龄>55岁(OR=6.213,95%CI:1.758～21.955)是CFRmin减低的危险因素;糖尿病是负荷MBF减低的危险因素(OR=9.444,95%CI:1.912～46.646);潜在危险因素是CFRmean减低的危险因素(OR=18.667,95%CI:2.807～124.145)。结论:(1)心血管病危险因素对静息MBF影响很小;(2)年龄、性别对负荷MBF、CFR有影响;(3)传统心血管病危险因素中,糖尿病对负荷MBF、CFR的影响不容忽视;(4)相比传统心血管病危险因素,潜在危险因素对CFR的影响更为显著,需高度重视,及时纠正或预防。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51179116,51109155)
文摘This paper studies the wall-bounded flow around a cylindrical at a high Reynolds numbers body in a determined computational domain, with simulations of the 3-D, turbulent concentric annulus flow in a straight pipe. Numerical results show that a reversing zone, appearing as a tongue zone with nested velocities higher than the surrounding area, exists behind the cylindrical body. The annulus space is a region of high velocity and low pressure. The zero velocity, of combined the X- velocity and the Y- velocity, exists in the cross sections and no vortex shedding is formed behind the attaching cylinders. Among all investigated effecting factors, the diameters of the attaching and the main cylinders affect the wake feature behind the cylindrical body while the main cylinder length does not affect the distribution tendency of the flow field. The diameters of the main cylinder and the pipe affect the pressure values and the distribution tendencies on the main cylinder surface. Obviously, the increase of the pipe diameter reduces the drag coefficient of the cylindrical body and the increase of the diameter of the main cylinder increases the drag coefficient greatly. The numerical investigation of the concentric annulus flow provides foundations for further improvements of the intricate flow studies.
文摘目的分析新生儿肺炎(NP)患儿经加温湿化高流量鼻导管通气(HHFNC)治疗失败的危险因素,构建预测模型并评估其预测效能。方法选取2023年2月至2024年10月南阳市中心医院收治的130例NP患儿,均采用HHFNC作为主要呼吸支持治疗方式。依据HHFNC治疗效果分为治疗成功组、治疗失败组,单因素、多因素logistic回归分析法筛选NP患儿HHFNC治疗失败的影响因素。基于上述影响因素构建NP患儿HHFNC治疗失败风险列线图模型,并评估列线图模型预测效能。结果采用HHFNC作为主要呼吸支持治疗方式的130例NP患儿中,22例(16.92%)患儿HHFNC治疗失败,108例(83.08%)患儿HHFNC治疗成功。治疗成功组、治疗失败组咽喉分泌物清理不及时比例、出生后5 min Apgar评分、HHFNC治疗前降钙素原(PCT)、25羟维生素D(25-OH-D)、呼吸评分(RS)、氧合指数(OI)及HHFNC初始吸入氧浓度(FiO_(2))差异有统计学意义(P<0.05)。多因素logistic回归分析,结果显示,咽喉分泌物清理不及时(OR=1.352)、HHFNC治疗前PCT(OR=1.329)、HHFNC治疗前RS(OR=1.124)、HHFNC初始FiO_(2)(OR=1.042)是NP患儿HHFNC治疗失败的危险因素(P<0.05),出生后5 min Apgar评分(OR=0.742)、HHFNC治疗前25-OH-D(OR=0.710)、HHFNC治疗前OI(OR=0.804)是NP患儿HHFNC治疗失败的保护因素(P<0.05)。基于上述影响因素构建NP患儿HHFNC治疗失败风险列线图模型,结果显示,该列线图模型预测值与实测值差异无统计学意义(χ^(2)=2.025,P=0.228),预测NP患儿HHFNC治疗失败的敏感度、特异度、曲线下面积分别为90.00%、78.00%、0.889(95%CI:0.752~0.945),且当预测概率阈值0.20~0.75时,对NP患儿采取干预措施,患儿净获益情况最佳。结论NP患儿HHFNC治疗失败受咽喉分泌物清理不及时、出生后5 min Apgar评分、HHFNC治疗前PCT、25-OH-D、RS、OI及HHFNC初始FiO_(2)的影响。本研究构建的列线图模型预测NP患儿HHFNC治疗失败的准确度、区分度均较高。
文摘目的:探讨心血管病危险因素对无或轻度冠状动脉(冠脉)狭窄的非血流受限人群的心肌血流量(MBF)及冠脉血流储备(CFR)的影响。方法:回顾性分析在本科室完成13N-氨水正电子发射计算机断层成像(PET)心肌灌注显像(MPI)、冠脉计算机断层摄影术(CT)血管造影(CTA)或冠脉造影(CAG)检查提示无或轻度冠脉狭窄的68例受检者,收集整理一般资料(包括年龄、性别、体重指数)及冠心病传统危险因素(糖尿病、高血压、血脂异常、长期吸烟、心血管病家族史)、潜在危险因素(包括阻塞性睡眠呼吸暂停综合征、肿瘤术后化疗后、甲状腺功能亢进症),经绝对定量分析获得静息及负荷MBF、左心室整体CFR。用χ~2检验、二元Logistic回归法分析上述危险因素对心肌灌注的影响。结果:单因素分析发现,男性的负荷MBF低于女性[(3.02±0.72)ml/(min·gm) vs(3.77±0.86)ml/(min·gm),χ~2=3.886,P=0.049],年龄>55岁受试者的CFR最小值(CFRmin)较≤55岁者减低(2.12±0.37 vs2.62±0.67,χ~2=10.236,P=0.001),糖尿病患者CFRmin(2.17±0.44 vs 2.51±0.65,χ~2=5.798,P=0.016)、负荷MBF[(2.79±0.64)ml/(min·gm) vs(3.57±0.86)ml/(min·gm),χ~2=7.053,P=0.008]低于无糖尿病者,存在潜在危险因素人群的CFR平均值(CFRmean)低于无潜在危险因素人群(2.42±0.44 vs 3.30±0.72,P=0.003)。多因素Logistic回归分析结果提示,糖尿病(OR=5.471,95%CI:1.040～28.788)、年龄>55岁(OR=6.213,95%CI:1.758～21.955)是CFRmin减低的危险因素;糖尿病是负荷MBF减低的危险因素(OR=9.444,95%CI:1.912～46.646);潜在危险因素是CFRmean减低的危险因素(OR=18.667,95%CI:2.807～124.145)。结论:(1)心血管病危险因素对静息MBF影响很小;(2)年龄、性别对负荷MBF、CFR有影响;(3)传统心血管病危险因素中,糖尿病对负荷MBF、CFR的影响不容忽视;(4)相比传统心血管病危险因素,潜在危险因素对CFR的影响更为显著,需高度重视,及时纠正或预防。
