133 research outputs found

    Heterogeneous Agent Model With Real Business Cycle With Application In Optimal Tax Policy And Social Welfare Reform

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    In this paper, we develop a dynamic stochastic general equilibrium (DSGE) model with financial friction and incomplete risk-sharing among overlapping-generation (OLG) heterogeneous households. The economy is embedded with taxation system and social security system calibrated to current U.S. economy and tax policy, as well as elastic labor supply. Our baseline model can match wealth-income disparity and moment conditions in financial market as well as macroeconomic variables. In baseline setting, the mean risk-free rate is 1.36%\% per year, the unlevered equity premium is 4.08%\%, and Gini coefficient for labor earning and total income is 0.65 and 0.51 respectively. The equity risk premium is driven by incomplete risk sharing among household and participation barrier to equity market. Furthermore, our model can act as workhorse model for policy experiment including debt policy, wealth tax reform, capital income tax reform and social security system reform. This paper could be beneficial to policy maker to understand the impact of policy change to macroeconomy and household-level behavior

    Hemodynamic Quantifications By Contrast-Enhanced Ultrasound:From In-Vitro Modelling To Clinical Validation

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    Hemodynamic Quantifications By Contrast-Enhanced Ultrasound:From In-Vitro Modelling To Clinical Validation

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    A Transfer Learning Approach for Malignant Prostate Lesion Detection on Multiparametric MRI

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    Purpose: In prostate focal therapy, it is important to accurately localize malignant lesions in order to increase biological effect of the tumor region while achieving a reduction in dose to noncancerous tissue. In this work, we proposed a transfer learning–based deep learning approach, for classification of prostate lesions in multiparametric magnetic resonance imaging images. Methods: Magnetic resonance imaging images were preprocessed to remove bias artifact and normalize the data. Two state-of-the-art deep convolutional neural network models, InceptionV3 and VGG-16, were pretrained on ImageNet data set and retuned on the multiparametric magnetic resonance imaging data set. As lesion appearances differ by the prostate zone that it resides in, separate models were trained. Ensembling was performed on each prostate zone to improve area under the curve. In addition, the predictions from lesions on each prostate zone were scaled separately to increase the area under the curve for all lesions combined. Results: The models were tuned to produce the highest area under the curve on validation data set. When it was applied to the unseen test data set, the transferred InceptionV3 model achieved an area under the curve of 0.81 and the transferred VGG-16 model achieved an area under the curve of 0.83. This was the third best score among the 72 methods from 33 participating groups in ProstateX competition. Conclusion: The transfer learning approach is a promising method for prostate cancer detection on multiparametric magnetic resonance imaging images. Features learned from ImageNet data set can be useful for medical images

    Analysis of the control strategy of range extender system on the vehicle NVH performance

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    With focus on NVH performance, this paper studies the range extender system control strategy such as the initial start speed, operating points, speed up and down control method between operating points of the range extender, etc. At the same time, the confirmation of the operating points of the range extender based on the full vehicle frequency distribution and vibration and noise level of key points (seat rail, driver’s inner ear) was performed. Finally, we conducted objective test and compared the test data with benchmark vehicles

    .Blood flow patterns estimation in the left ventricle with low-rate 2D and 3D dynamic contrast-enhanced ultrasound

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    a b s t r a c t Background and Objective : Left ventricle (LV) dysfunction always occurs at early heart-failure stages, pro- ducing variations in the LV flow patterns. Cardiac diagnostics may therefore benefit from flow-pattern analysis. Several visualization tools have been proposed that require ultrafast ultrasound acquisitions. However, ultrafast ultrasound is not standard in clinical scanners. Meanwhile techniques that can handle low frame rates are still lacking. As a result, the clinical translation of these techniques remains limited, especially for 3D acquisitions where the volume rates are intrinsically low. Methods : To overcome these limitations, we propose a novel technique for the estimation of LV blood velocity and relative-pressure fields from dynamic contrast-enhanced ultrasound (DCE-US) at low frame rates. Different from other methods, our method is based on the time-delays between time-intensity curves measured at neighbor pixels in the DCE-US loops. Using Navier-Stokes equation, we regularize the obtained velocity fields and derive relative-pressure estimates. Blood flow patterns were characterized with regard to their vorticity, relative-pressure changes (dp/dt) in the LV outflow tract, and viscous energy loss, as these reflect the ejection efficiency. Results : We evaluated the proposed method on 18 patients (9 responders and 9 non-responders) who un- derwent cardiac resynchronization therapy (CRT). After CRT, the responder group evidenced a significant (p < 0.05) increase in vorticity and peak dp/dt, and a non-significant decrease in viscous energy loss. No significant difference was found in the non-responder group. Relative feature variation before and after CRT evidenced a significant difference (p < 0.05) between responders and non-responders for vorticity and peak dp/dt. Finally, the method feasibility is also shown with 3D DCE-US. Conclusions : Using the proposed method, adequate visualization and quantification of blood flow patterns are successfully enabled based on low-rate DCE-US of the LV, facilitating the clinical adoption of the method using standard ultrasound scanners. The clinical value of the method in the context of CRT is also shown
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