A 65-year-old woman was presented with acute ab- dominal pain. The initial heart rate was 170 beats/min and the ECG showed supraventricular tachycardia （Figure IA）. After intra-venous adenosine administered, it reco...A 65-year-old woman was presented with acute ab- dominal pain. The initial heart rate was 170 beats/min and the ECG showed supraventricular tachycardia （Figure IA）. After intra-venous adenosine administered, it recovered to sinus rhythm and the follow-up ECG showed WPW pattern （Figure 1B）. The echocardiography revealed mitral valve prolapse of mid portion of anteromedial valve leaflet （A2） with severe mitral regurgitation （MR） （Figure 2）.展开更多
AIM:To determine if liver stiffness(LS) measurements by means of transient elastography(TE) correlate with the presence of significant esophageal varices(EV) and if they can predict the occurrence of variceal bleeding...AIM:To determine if liver stiffness(LS) measurements by means of transient elastography(TE) correlate with the presence of significant esophageal varices(EV) and if they can predict the occurrence of variceal bleeding.METHODS:We studied 1000 cases of liver cirrhosis divided into 2 groups:patients without EV or with grade 1 varices(647 cases) and patients with significant varices(grade 2 and 3 EV)(353 cases).We divided the group of 540 cases with EV into another 2 subgroups:without variceal hemorrhage(375 patients) and patients with a history of variceal bleeding(165 cases).We compared the LS values between the groups using the unpaired t-test and we established cut-off LS values for the presence of significant EV and for the risk of bleeding by using the ROC curve.RESULTS:The mean LS values in the 647 patients without or with grade 1 EV was statistically significantly lower than in the 353 patients with significant EV(26.29 ± 0.60 kPa vs 45.21 ± 1.07 kPa,P < 0.0001).Using the ROC curve we established a cut-off value of 31 kPa for the presence of EV,with 83% sensitivity(95%CI:79.73%-85.93%) and 62% specificity(95% CI:57.15%-66.81%),with 76.2% positive predictive value(PPV)(95% CI:72.72%-79.43%) and 71.3% negative predictive value(NPV)(95% CI:66.37%-76.05%)(AUROC 0.7807,P < 0.0001).The mean LS values in the group with a history of variceal bleeding(165 patients) was statistically significantly higher than in the group with no bleeding history(375 patients):51.92 ± 1.56 kPa vs 35.20 ± 0.91 kPa,P < 0.0001).For a cut-off value of 50.7 kPa,LS had 53.33% sensitivity(95% CI:45.42%-61.13%) and 82.67% specificity(95% CI:78.45%-86.36%),with 82.71% PPV(95% CI:78.5%-86.4%) and 53.66% NPV(95% CI:45.72%-61.47%)(AUROC 0.7300,P < 0.0001) for the prediction of esophageal bleeding.展开更多
The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study. A new 3D computational fluid dynamics (CFD) analysis method is applied. Also, the quasi-coupli...The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study. A new 3D computational fluid dynamics (CFD) analysis method is applied. Also, the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearing and rotor dynamics is considered in the analysis. Based on the structured mesh, a new approach for mesh movement is proposed to update the mesh volume when the journal moves during the fluid dynamics simula- tion of an oil film. Existing dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The movement of the journal is obtained by solving the moving equations of the rotor-bearing system with the calculated film pressure as the boundary condition of the load. The data exchange between fluid dynamics and rotor dynamics is realized by data files. Results obtained from the CFD model were consistent with previous experimental results on misaligned journal bearings. Film pressure, oil film force, friction torque, misalignment moment and attitude angle were calculated and compared for mis- aligned and aligned journal bearings. The results indicate that bearing performances are greatly affected by misalignment which is caused by unbalanced excitation, and the CFD method based on the fluid-structure interaction (FSI) technique can effectively predict the transient flow field of a misaligned journal bearing in a rotor-bearing system.展开更多
文摘A 65-year-old woman was presented with acute ab- dominal pain. The initial heart rate was 170 beats/min and the ECG showed supraventricular tachycardia （Figure IA）. After intra-venous adenosine administered, it recovered to sinus rhythm and the follow-up ECG showed WPW pattern （Figure 1B）. The echocardiography revealed mitral valve prolapse of mid portion of anteromedial valve leaflet （A2） with severe mitral regurgitation （MR） （Figure 2）.
文摘AIM:To determine if liver stiffness(LS) measurements by means of transient elastography(TE) correlate with the presence of significant esophageal varices(EV) and if they can predict the occurrence of variceal bleeding.METHODS:We studied 1000 cases of liver cirrhosis divided into 2 groups:patients without EV or with grade 1 varices(647 cases) and patients with significant varices(grade 2 and 3 EV)(353 cases).We divided the group of 540 cases with EV into another 2 subgroups:without variceal hemorrhage(375 patients) and patients with a history of variceal bleeding(165 cases).We compared the LS values between the groups using the unpaired t-test and we established cut-off LS values for the presence of significant EV and for the risk of bleeding by using the ROC curve.RESULTS:The mean LS values in the 647 patients without or with grade 1 EV was statistically significantly lower than in the 353 patients with significant EV(26.29 ± 0.60 kPa vs 45.21 ± 1.07 kPa,P < 0.0001).Using the ROC curve we established a cut-off value of 31 kPa for the presence of EV,with 83% sensitivity(95%CI:79.73%-85.93%) and 62% specificity(95% CI:57.15%-66.81%),with 76.2% positive predictive value(PPV)(95% CI:72.72%-79.43%) and 71.3% negative predictive value(NPV)(95% CI:66.37%-76.05%)(AUROC 0.7807,P < 0.0001).The mean LS values in the group with a history of variceal bleeding(165 patients) was statistically significantly higher than in the group with no bleeding history(375 patients):51.92 ± 1.56 kPa vs 35.20 ± 0.91 kPa,P < 0.0001).For a cut-off value of 50.7 kPa,LS had 53.33% sensitivity(95% CI:45.42%-61.13%) and 82.67% specificity(95% CI:78.45%-86.36%),with 82.71% PPV(95% CI:78.5%-86.4%) and 53.66% NPV(95% CI:45.72%-61.47%)(AUROC 0.7300,P < 0.0001) for the prediction of esophageal bleeding.
基金supported by the National High-Tech R&D (863) Program of China (No. 2009AA04Z413)the Natural Science Foundation of Zhejiang Province (No. Y1110109),China
文摘The effects of journal misalignment on the transient flow of a finite grooved journal bearing are presented in this study. A new 3D computational fluid dynamics (CFD) analysis method is applied. Also, the quasi-coupling calculation of transient fluid dynamics of oil film in journal bearing and rotor dynamics is considered in the analysis. Based on the structured mesh, a new approach for mesh movement is proposed to update the mesh volume when the journal moves during the fluid dynamics simula- tion of an oil film. Existing dynamic mesh models provided by FLUENT are not suitable for the transient oil flow in journal bearings. The movement of the journal is obtained by solving the moving equations of the rotor-bearing system with the calculated film pressure as the boundary condition of the load. The data exchange between fluid dynamics and rotor dynamics is realized by data files. Results obtained from the CFD model were consistent with previous experimental results on misaligned journal bearings. Film pressure, oil film force, friction torque, misalignment moment and attitude angle were calculated and compared for mis- aligned and aligned journal bearings. The results indicate that bearing performances are greatly affected by misalignment which is caused by unbalanced excitation, and the CFD method based on the fluid-structure interaction (FSI) technique can effectively predict the transient flow field of a misaligned journal bearing in a rotor-bearing system.
