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PC-MRI技术在脑脊液循环中的应用 被引量:2
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作者 盛范龙 王长军 +1 位作者 董辉 修建军 《中国中西医结合影像学杂志》 2019年第6期562-565,共4页
目的:分析MRI相位对比成像(PC-MRI)在中脑导水管区脑脊液检测时的流动曲线,以及流速编码(VENC)、导水管位置、ROI面积3个因素对结果的影响。方法:纳入30例志愿者,10例(第1组)定位导水管中段,VENC=5、10、20、70 cm/s扫描4次,ROI=0.03 cm... 目的:分析MRI相位对比成像(PC-MRI)在中脑导水管区脑脊液检测时的流动曲线,以及流速编码(VENC)、导水管位置、ROI面积3个因素对结果的影响。方法:纳入30例志愿者,10例(第1组)定位导水管中段,VENC=5、10、20、70 cm/s扫描4次,ROI=0.03 cm^2;10例(第2组)VENC=20 cm/s、于导水管上口、中段、下口扫描3次,ROI=0.03 cm^2;10例(第3组)定位导水管中段、VENC=20 cm/s扫描,绘制ROI=0.01、0.02、0.03、0.04 cm 24次。ROI绘制后系统自动生成流动曲线和各流动参数。结果:①流动曲线呈正、余弦波和“U”型波多种形态。②第1组VENC=5 cm/s均见混淆伪影、流动曲线呈无规律波浪状,与VENC=10、20、70 cm/s时的峰值流速、绝对每博输出量(ASV)差异均有统计学意义(均P<0.05);VENC=10、20、70 cm/s时无混淆伪影,流动曲线呈规律性,各测量结果差异均无统计学意义(均P>0.05)。③第2组导水管不同部位所测流动参数,差异均无统计学意义(均P>0.05)。④第3组ASV随ROI增大而增加,差异有统计学意义(P<0.05);不同ROI时的峰值流速、平均流速及回返系数差异均无统计学意义(均P>0.05)。结论:①导水管区脑脊液流动曲线形态多样,但均反映双向往复波动式流动,延长诸波形具有一致性。②VENC=5 cm/s取值过低,70 cm/s取值略高,10~20 cm/s较合理;③扫描导水管不同部位对测量结果无影响;④ROI面积与ASV及回返系数呈正比,对峰值流速、平均流速无影响。 展开更多
关键词 脑脊液 流动曲线 回返系数 磁共振成像
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Return threshold model analysis of two stock markets: Evidence study of Italy and Germany's stock returns
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作者 Wann-Jyi Horng Yu-Cheng Chen Weir-Sen Lin 《Chinese Business Review》 2010年第1期23-35,共13页
This paper discusses the model construction and the association between the Italy and the Germany's stock markets. The period of study data is from January 3, 2000 to June 30, 2008. This paper also utilizes Student'... This paper discusses the model construction and the association between the Italy and the Germany's stock markets. The period of study data is from January 3, 2000 to June 30, 2008. This paper also utilizes Student's t distribution to analyze the proposed model. The empirical results show that the two stock markets are mutually affected each other, and the dynamic conditional correlation (DCC) and the bivariate asymmetric-GARCH (1, 2) model is appropriate in evaluating the relation between them. The empirical result also indicates that Italy and Germany's stock markets show a positive relationship. The average value of correlation coefficient equals to 0.8424, which implies that the two stock markets return volatility have a synchronized influence on each other. In addition, the empirical result also shows that there is an asymmetrical effect between Italy and the Germany's stock markets, and demonstrates that the good news and bad news of the stock returns' volatility will produce the different variation risks for Italy and the Germany's stock price markets. 展开更多
关键词 stock market returns GARCH model asymmetric effect GJR-GARCH model bivariate asymmetric GARCH model
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Banks' Earnings, Risks and Returns in China
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作者 Cheng Fan Fah Annuar Nasir 《Chinese Business Review》 2011年第1期21-28,共8页
This study aims to find the effect of financial risks, price risks and market risks on the Earning Response Coefficients (ERC) for China Commercial Banks. The research methodologies use the traditional cumulative ab... This study aims to find the effect of financial risks, price risks and market risks on the Earning Response Coefficients (ERC) for China Commercial Banks. The research methodologies use the traditional cumulative abnormal returns and the unexpected earning as the main dependent and independent variables. The evidences show that: (1) There is a strong returns-to-earnings relation for banks; (2) The liquidity risk has information content beyond earnings changes in the returns-to-earnings relation. This probably due to the reason that managers of banks find the level of liquidity that fulfilled the need of investors and at the same time earns good profits for the banks. 展开更多
关键词 earnings response coefficients LIQUIDITY CREDIT INTEREST solvency risk
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Performance Back-deduction from a Loading to Flow Coefficient Map:Application to Radial Turbine
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作者 Xavier CARBONNEAU Nicolas BINDER 《Journal of Thermal Science》 SCIE EI CAS CSCD 2012年第6期509-517,共9页
Radial turbine stages are often used for applications requiring off-design operation,as turbocharging for instance.The off-design ability of such stages is commonly analyzed through the traditional turbine map,plottin... Radial turbine stages are often used for applications requiring off-design operation,as turbocharging for instance.The off-design ability of such stages is commonly analyzed through the traditional turbine map,plotting the reduced mass-flow against the pressure-ratio,for reduced-speed lines.However,some alternatives are possible,such as the flow-coefficient(Ψ)to loading-coefficient(φ)diagram where the pressure-ratio lines are actually straight lines,very convenient property to perform prediction.A robust method re-creating this map from a predicted Ψ-φ diagram is needed.Recent work has shown that this back-deduction quality,without the use of any loss models,depends on the knowledge of an intermediate pressure-ratio.A modelization of this parameter is then proposed.The comparison with both experimental and CFD results is presented,with quite good agreement for mass flow rate and rotational speed,and for the intermediate pressure ratio.The last part of the paper is dedicated to the application of the intermediate pressure-ratio knowledge to the improvement of the deduction of the pressure ratio lines in the Ψ-φ diagram.Beside this improvement,the back-deduction method of the classical map is structured,applied and evaluated. 展开更多
关键词 Radial turbine OFF-DESIGN flow coefficient load coefficient PERFORMANCE
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