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761 results on '"Shi, Yanyan"'

1. Filtered finite difference methods for nonlinear Schr\'odinger equations in semiclassical scaling

Author

Shi, Yanyan and Lubich, Christian

Subjects
Mathematics - Numerical Analysis
Abstract

This paper introduces filtered finite difference methods for numerically solving a dispersive evolution equation with solutions that are highly oscillatory in both space and time. We consider a semiclassically scaled nonlinear Schr\"odinger equation with highly oscillatory initial data in the form of a modulated plane wave. The proposed methods do not need to resolve high-frequency oscillations in both space and time by prohibitively fine grids as would be required by standard finite difference methods. The approach taken here modifies traditional finite difference methods by incorporating appropriate filters. Specifically, we propose the filtered leapfrog and filtered Crank--Nicolson methods, both of which achieve second-order accuracy with time steps and mesh sizes that are not restricted in magnitude by the small semiclassical parameter. Furthermore, the filtered Crank--Nicolson method conserves both the discrete mass and a discrete energy. Numerical experiments illustrate the theoretical results.

Published
2024

8. Development and Reliability and Validity Test of Cardiotoxicity Risk Assessment Scale for Breast Cancer Patients Undergoing Chemotherapy

Author

YAO Shanshan, MA Zhuyue, SHI Yanyan, WU Yuqing, ZHANG Liuliu, CHEN Mingxia, WU Bing, CHENG Fang

Subjects
breast neoplasms, chemotherapy side effects, cardiotoxicity, qualitative research, reliability and validity test, Medicine
Abstract

Background Cardiotoxicity is a leading cause of mortality among breast cancer patients treated with chemotherapy. Therefore, an early risk assessment is vital for the clinical prevention and treatment of cardiotoxicity in breast cancer patients treated with chemotherapy, although a recognized tool is scant in our country. Objective To develop a cardiotoxic risk assessment scale for breast cancer patients undergoing chemotherapy and to test its reliability and validity. Methods Through reviewing relevant domestic and international literatures, a pool involving items to assess the risk of cardiotoxicity in breast cancer patients treated with chemotherapy was created. Semi-structured interviews with healthcare providers at Jiangsu Cancer Hospital from September to October 2022 were performed by purposive sampling, thus primarily forming a tool of items for the cardiotoxic risk assessment scale. In addition, breast cancer patients treated with chemotherapy in Jiangsu Cancer Hospital were randomly selected for a pre-survey and validation of the reliability and validity of the scale. Ranked by the score of the cardiotoxic risk assessment scale, the top 27% of participants were assigned into the high-score group, and the remaining were in the low-score group. Cronbach's α coefficient was used to evaluate the internal consistency of the scale. Validity of the scale was verified by measuring the item-level content validity index (I-CVI) and scale-level content validity index (S-CVI). Exploratory factor analysis was performed to assess the structural validity. Receiver operating characteristic (ROC) curves were plotted, and the area under tcurve (AUC) was calculated to determine the predictive validity. Results Twenty healthcare providers were included in the semi-structured interviews. After two rounds of expert consultations, a 19-item cardiotoxic risk assessment scale in breast cancer patients treated with chemotherapy was developed. In this study, there were 79 patients in the low-score group and 83 in the high-score group. No significant differences in the history of smoking, endocrine treatment and immunotherapy were detected between the two groups (P>0.05). Correlation analysis showed that the history of smoking and immunotherapy was not significantly correlated with the total scores (P>0.05). Eventually, three items of smoking history, history of endocrine treatment and history of immunotherapy were removed, forming a 16-item scale. The Cronbach's α coefficient, test-retest reliability and inter-rater reliability were 0.739, 0.983 and 0.984, respectively. Content validity results showed that I-CVI ranged from 0.83 to 1.00, and S-CVI was 0.98. Predictive validity results showed the AUC of 0.887 (95%CI=0.827-0.947, P

Published
2024
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10. Leapfrog methods for relativistic charged-particle dynamics

Author

Hairer, Ernst, Lubich, Christian, and Shi, Yanyan

Subjects
Mathematics - Numerical Analysis, Physics - Computational Physics, Physics - Plasma Physics, 65L05, 65P10, 78A35
Abstract

A basic leapfrog integrator and its energy-preserving and variational / symplectic variants are proposed and studied for the numerical integration of the equations of motion of relativistic charged particles in an electromagnetic field. The methods are based on a four-dimensional formulation of the equations of motion. Structure-preserving properties of the numerical methods are analysed, in particular conservation and long-time near-conservation of energy and mass shell as well as preservation of volume in phase space. In the non-relativistic limit, the considered methods reduce to the Boris algorithm for non-relativistic charged-particle dynamics and its energy-preserving and variational / symplectic variants., Comment: 18 pages, 3 figures

Published
2023

11. Drift approximation by the modified Boris algorithm of charged-particle dynamics in toroidal geometry

Author

Shi, Yanyan

Subjects
Mathematics - Numerical Analysis, Physics - Plasma Physics
Abstract

In this paper, we study the charged-particle dynamics under strong magnetic field in a toroidal axi-symmetric geometry. Using modulated Fourier expansions of the exact and numerical solutions, the long-term drift motion of the exact solution in toroidal geometry is derived and the error analysis of the large-stepsize modified Boris algorithm over long time scales is provided. Numerical experiments illustrate the theoretical results.

Published
2022

18. On a large-stepsize integrator for charged-particle dynamics

Author

Lubich, Christian and Shi, Yanyan

Subjects
Mathematics - Numerical Analysis, Physics - Plasma Physics
Abstract

Xiao and Qin [Computer Physics Comm., 265:107981, 2021] recently proposed a remarkably simple modification of the Boris algorithm to compute the guiding centre of the highly oscillatory motion of a charged particle with step sizes that are much larger than the period of gyrorotations. They gave strong numerical evidence but no error analysis. This paper provides an analysis of the large-stepsize modified Boris method in a setting that has a strong non-uniform magnetic field and moderately bounded velocities, considered over a fixed finite time interval. The error analysis is based on comparing the modulated Fourier expansions of the exact and numerical solutions, for which the differential equations of the dominant terms are derived explicitly. Numerical experiments illustrate and complement the theoretical results.

Published
2022

19. Persistent symptoms and risk factors predicting prolonged time to symptom-free after SARS‑CoV‑2 infection: an analysis of the baseline examination of the German COVIDOM/NAPKON-POP cohort

Author

Shi, Yanyan, Strobl, Ralf, Apfelbacher, Christian, Bahmer, Thomas, Geisler, Ramsia, Heuschmann, Peter, Horn, Anna, Hoven, Hanno, Keil, Thomas, Krawczak, Michael, Krist, Lilian, Lemhöfer, Christina, Lieb, Wolfgang, Lorenz-Depiereux, Bettina, Mikolajczyk, Rafael, Montellano, Felipe A., Reese, Jens Peter, Schreiber, Stefan, Skoetz, Nicole, Störk, Stefan, Vehreschild, Jörg Janne, Witzenrath, Martin, and Grill, Eva

Published
2023
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29. Large-stepsize integrators for charged-particle dynamics over multiple time scales

Author

Hairer, Ernst, Lubich, Christian, and Shi, Yanyan

Subjects
Mathematics - Numerical Analysis, Physics - Plasma Physics, 65L05, 65P10, 78A35, 78M25
Abstract

The Boris algorithm, a closely related variational integrator and a newly proposed filtered variational integrator are studied when they are used to numerically integrate the equations of motion of a charged particle in a non-uniform strong magnetic field, taking step sizes that are much larger than the period of the Larmor rotations. For the Boris algorithm and the standard (unfiltered) variational integrator, satisfactory behaviour is only obtained when the component of the initial velocity orthogonal to the magnetic field is filtered out. The particle motion shows varying behaviour over multiple time scales: fast Larmor rotation, guiding centre motion, slow perpendicular drift, near-conservation of the magnetic moment over very long times and conservation of energy for all times. Using modulated Fourier expansions of the exact and numerical solutions, it is analysed to which extent this behaviour is reproduced by the three numerical integrators used with large step sizes.

Published
2021

31. First-line induction chemotherapy with high-dose methotrexate versus teniposide in patients with newly diagnosed primary central nervous system lymphoma: a retrospective, multicenter cohort study

Author

Zhong, Kaili, Shi, Yanyan, Gao, Yuhuan, Zhang, Huilai, Zhang, Mingzhi, Zhang, Qiaohua, Cen, Xinan, Xue, Mei, Qin, Yan, Zhao, Yu, Zhang, Liling, Liang, Rong, Wang, Ningju, Xie, Yan, Yang, Yu, Liu, Aichun, Bao, Huizheng, Wang, Jingwen, Cao, Baoping, Zhang, Wei, and Zhang, Weijing

Published
2023
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39. AFTM:Anchor-free Object Tracking Method with Attention Features

Author

LI Xuehui, ZHANG Yongjun, SHI Dianxi, XU Huachi, SHI Yanyan

Subjects
deep learning, object tracking, siamese network, anchor-free, attention mechanism, Computer software, QA76.75-76.765, Technology (General), T1-995
Abstract

As an important branch in the field of computer vision,object tracking has been widely used in many fields such as intelligent video surveillance,human-computer interaction and autonomous driving.Although object tracking has achieved good development in recent years,tracking in complex environment is still a challenge.Due to problems such as occlusion,object deformation and illumination change,tracking performance will be inaccurate and unstable.In this paper,an effective object tracking method AFTM,is proposed with attention features.Firstly,this paper constructs an adaptively generated attention weight factor group,which implements an efficient adaptive fusion strategy for response map to improve the accuracy of object positioning and bounding box scale calculation in the process of classification and regression.Secondly,aiming at the class imbalance in the data set,the proposed method uses the dynamically scaled cross entropy loss as the loss function of the object positioning network,which can modify the optimization direction of the model and make the tracking performance more stable and reliable.Finally,this paper designs a corresponding learning rate adjustment strategy to stochastically average the weight of a number of models,which can enhance the generalization ability of the model.Experimental results on public data sets show that the proposed method has higher accuracy and more stable tracking performance in complex tracking environment.

Published
2023
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40. Efficient Scale Divide and Conquer Network for Object Detection

Author

Liu, Yangyang, Shi, Yanyan, Qiao, Ziteng, Zhang, Yi, Yang, Shaowu, Shi, Dianxi, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Khanna, Sankalp, editor, Cao, Jian, editor, Bai, Quan, editor, and Xu, Guandong, editor

Published
2022
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41. A High Sensitivity Sensor for Reconstruction of Conductivity Distribution in Region of Interest

Author

Tian, Zhiwei, Shi, Yanyan, Fu, Feng, Wu, Yuehui, Gao, Zhen, Lou, Yajun, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Yang, Qingxin, editor, Liang, Xidong, editor, Li, Yaohua, editor, and He, Jinghan, editor

Published
2022
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