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Adversarial data splitting for domain generalization

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Science China(Information Sciences) 2024年第5期67卷 28-42页

作者： xiang gu Jian SUN Zongben XU School of Mathematics and Statistics Xi'an Jiaotong University

Domain generalization aims to learn a model that is generalizable to an unseen target domain,which is a fundamental and challenging task in machine learning for out-of-distribution generalization. This paper proposes a novel domain generalization approach that enforces the learned model to be able to generalize well over the train/val subset splitting of the training dataset. This idea is modeled herein as an adversarial data splitting framework, formulated as a min-max optimization problem inspired by the metalearning approach. The min-max optimization problem is solved by iteratively splitting the training dataset into the training and val subsets to maximize the domain shift measured by the objective function and updating the model parameters to enable the model to generalize well from the training subset to the val subset by minimizing the objective function. This adversarial training approach does not assume the known domain labels of the training data; instead, it automatically investigates the “hard” splitting of the train/val subsets to learn the generalizable model. Extensive experimental results using three benchmark datasets demonstrate the superiority of this approach. In addition, we derive a generalization error bound for the theoretical understanding of our proposed approach.

关键词： domain generalization adversarial learning data splitting meta-learning out of distribution

Personalized image-based templates for precise acetabular prosthesis placement in total hip arthroplasty:a pilot study

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Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第9期11卷 673-680页

作者： Bin CHEN Sheng-xiang XIAO Peng-cheng gu xiang-jin LIN Department of Orthopaedics the First Affiliated Hospital School of Medicine Zhejiang University Hangzhou 310003 China

Objective：In order to achieve accurate implantation of the acetabular prosthesis in total hip arthroplasty（THA）,we designed individual templates based on a three-dimensional（3D） model generated from computed tomography（CT） ***：Individual templates were designed for 12 patients who underwent THA.A physical template was designed to conform to the contours of the patient＇s acetabulum and to confirm the rotation of the acetabular *** guided the acetabular component ***：The preoperative and postoperative X-ray and CT scans were obtained to assess the location with respect to the accuracy of the acetabular *** all patients,the abduction angle of the acetabular component was 46.7°to 54.3°and the anteversion angle was 11.3°to 18.5°Conclusions：The assessment of postoperative CT scans demonstrated higher accuracy of the acetabular component bore when used with the individual ***,the individual template can be an alternative to the computer-assisted navigation systems,with a good cost-performance ratio.

关键词： Total hip arthroplasty Templates Acetabular prosthesis

The utility of two-dimensional shear wave elastography and texture analysis for monitoring liver fibrosis in rat model

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Hepatobiliary & Pancreatic Diseases International 2021年第1期20卷 46-52页

作者： Li-Hong gu guang-xiang gu Ping Wan Feng-Hua Li Qiang Xia Department of Liver Surgery Renji HospitalSchool of MedicineShanghai Jiaotong UniversityShanghai 200127China Department of Ultrasound Renji HospitalSchool of MedicineShanghai Jiaotong UniversityShanghai 200127China

Background:Liver fibrosis is a common pathological change caused by a variety of *** diagnosis and timely treatment can reverse or delay disease progression and improve the *** study aimed to assess the potential utility of two-dimensional shear wave elastography and texture analysis in dynamic monitoring of the progression of liver fibrosis in rat ***:Twenty rats were divided into control group(n=4)and experimental groups(n=4 per group)with carbon tetrachloride administration for 2,3,4,and 6 *** liver stiffness measurement was performed by two-dimensional shear wave elastography,while the optimal texture analysis subsets to distinguish fibrosis stage were generated by *** results of elastography and texture analysis were validated through comparing with ***:Liver stiffness measurement was 6.09±0.31 kPa in the control group and 7.10±0.41 kPa,7.80±0.93 kPa,8.64±0.93 kPa,9.91±1.13 kPa in the carbon tetrachloride induced groups for 2,3,4,6 weeks,respectively(P<0.05).By texture analysis,histogram and co-occurrence matrix had the most frequency texture parameters in staging liver *** operating characteristic curve of liver elasticity showed that the sensitivity and specificity were 95.0%and 92.5%to discriminate liver fibrosis and non-fibrosis,*** texture analysis,five optimal parameters were selected to classify liver fibrosis and ***:Two-dimensional shear wave elastography showed potential applications for noninvasive monitoring of the progression of hepatic fibrosis,even in mild *** analysis can further extract and quantify the texture features in ultrasonic image,which was a supplementary to further visual information and acquired high diagnostic accuracy for severe fibrosis.

关键词： Shear wave elastography Ultrasound Texture analysis Fibrosis Rat

A multiaxial elastic potential with error-minimizing approximation to rubberlike elasticity

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Acta Mechanica Sinica 2015年第5期31卷 637-646页

作者： Zhi-xiang gu Lu Yuan Zheng-Nan Yin Heng Xiao State Key Laboratory of Advanced Special Steels Shanghai University Shanghai Institute of Applied Mathematics and Mechanics Shanghai University

This study is concerned with a new,explicit approach by means of which forms of the large strain elastic potential for multiaxial rubberlike elasticity may be obtained based on data for a single deformation *** a departure from usual studies,here for the first time errors may be estimated and rendered minimal for all possible deformation modes and,furthermore,failure behavior may be *** examples presented are in accurate agreement with Treloar＇s well-known data.

关键词： Rubberlike elasticity Large deformations Elastic potential Explicit approach Minimized errors

A Note on Exact Solutions to Linear Differential Equations by the Matrix Exponential

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Advances in Applied Mathematics and Mechanics 2009年第4期1卷 573-580页

作者： Wen-Xiu Ma xiang gu Liang Gao Department of Mathematics and Statistics University of South FloridaTampaFL 33620-5700USA Department of Physics University of South FloridaTampaFL 33620-5700USA Department of Applied Mathematics Northwestern Polytechnical UniversityXi’anShaanxi 710072P.R.China

It is known that the solution to a Cauchy problem of linear differential equations:x'(t)=A(t)x(t),with x(t0)=x0,can be presented by the matrix exponential as exp(∫_(t0)^(t)A(s)ds)x0,if the commutativity condition for the coefficient matrix A(t)holds:[∫_(t0)^(t)A(s)ds,A(t)]=0.A natural question is whether this is true without the commutativity *** give a definite answer to this question,we present two classes of illustrative examples of coefficient matrices,which satisfy the chain rule d/dt exp(∫_(t0)^(t)A(s)ds)=A(t)exp(∫_(t0)^(t)A(s)ds),but do not possess the commutativity *** presented matrices consist of finite-times continuously differentiable entries or smooth entries.

关键词： Cauchy problem chain rule commutativity condition fundamental matrix solution

Syntheses and Crystal Structures of Methyl 2-(4,5-Dibromo-1-methylpyrrole-2-carbonylamino)-3-phenylpropanoate and 4,5-Dibromo-1-methyl-2- trichloroacetylpyrrole

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Chinese Journal of Structural Chemistry 2006年第2期25卷 153-158页

作者： ZENG xiang-Chao gu Jian XU Shi-Hai LIU Po-Run Department of Chemistry Jinan University Guangzhou 510632 China

4,5-Dibromo-1-methyl-2-trichloroacetylpyrrole Ⅰ, prepared by the reaction of 1-methyl-2-trichloroacetylpyrrole with Br2 in 98.6 % yield, was condensed with methyl L-2-amino-3- phenylpropanoate to afford methyl 2-（4,5-dibromo-1-methylpyrrole-2-carboxmido）-3-phenylpropanoate Ⅱ in 90.8% yield. Crystal data for Ⅰ： monoclinic system, space group P21/c with a = 8.595（3）, b = 10.900（4）, c = 12.321（5） ,A°,β = 92.292（7）°, V = 1153.4（8）A°^3, Dc = 2.213 g/cm^3, F（000） = 728, CTH4Br2Cl3NO, Mr = 384.28, λ = 0.71073 A°, μ（MoKa） = 7.688 mm^-1, Z = 4, R = 0.0338 and wR2 = 0.0840 for 1963 observed reflections with I 〉 2a（I）. Crystal data for Ⅱ： monoclinic system, space group P21 with a = 4.886（2）, b = 15.921（8）, c = 11.635（6） A°,β = 101.803（9）°, V = 885.9（7） A°^3, Dc = 1.665 g/cm^3, F（000） = 440, C16H16Br2N2O3, Mr = 444.13, λ = 0.71073 A°, μ（MoKa） = 4.590 mm^-1, Z = 2, R = 0.0335 and wR2 = 0.0837 for 3191 observed reflections with I 〉 2σ（I）. The crystal structure reveals that compound Ⅱ forms the one-dimensional chain structure via the intermolecular hydrogen bonds of N（2）-H…O（1）.

关键词： methyl 2-(4,5-dibromo-1-methylpyrrole-2-carbonylamino)-3-phenylpropanoate,synthesis crystal structure 4,5-dibromo-1-methyl-2-trichloroacetylpyrrole

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fine concrete shells

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Frontiers of Structural and Civil Engineering 2023年第10期17卷 1554-1570页

作者： Qin ZHANG Qiao-Chu YANG xiang-Lin gu Yong JIANG Hai-Yang ZHU College of Civil and Transportation Engineering Hohai UniversityNanjing 210024China Key Laboratory of Performance Evolution and Control for Engineering Structures of Ministry of Education Tongji UniversityShanghai 200092China School of Civil Engineering Suzhou University of Science and TechnologySuzhou 215009China

This paper proposes an innovative column composed of a core column(including both reinforced concrete(RC)and plain concrete(PC)columns)and a prefabricated textile-reinforced fine concrete(TRC)*** study the confinement properties of TRC shells on this novel type of concrete column,20 circular specimens,including 12 PC columns and 8 RC columns,were prepared for axial compressive *** key parameters,including the column size,reinforcing ratio of the carbon textile,concrete strength,and stirrup spacing,were *** results indicated that the compressive properties of the columns were improved by increasing the reinforcing ratio of the textile *** the case of TRC-confined PC columns,the maximum improvement in the peak load was 56.3%,and for TRC-confined RC columns,the maximum improvement was 60.2%.Based on the test results,an analytical model that can be used to calculate the stress–strain curves of prefabricated TRC shell-confined concrete columns has been *** calculated curves predicted by the proposed model agreed well with the test results.

关键词： textile-reinforced fine concrete prefabricated shell confined concrete column confinement properties stress–strain relationship

Peripheral blood stem cells transplantation in patients with heart failure after myocardial infarction:their efficiency and safety

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Journal of Geriatric Cardiology 2007年第4期4卷 233-237页

作者： xiang gu Houtian Xu Minghui Li Department of Cardiology Affiliated Subei People''s Hosptial Yangzhou University Yangzhou 225001 China Department of Cardiology Affiliated Subei People''s Hosptial Yangzhou University Yangzhou 225001 China Department of Cardiology Affiliated Subei People''s Hosptial Yangzhou University Yangzhou 225001 China

Objective To compare the efficiency and safety of intracoronary transplantation of peripheral blood stem cells (PBSC) between elderly and younger patients with heart failure after myocardial infarction (MI). Methods Twenty-five patients with heart failure after MI were divided into aged group(≥60 years,n=13) and non-aged group(<60years,n=12)to receive intracoronary PBSC transplantation (PBSCT) following bone marrow cells mobilized by granulocyte colony-stimulating factor(G-CSF). Clinical data including coronary lesion characteristic, left ventricular shape,infarct region area and cardiac function, as well as adverse side effects between the two groups were compared. Left ventricular function was evaluated before and 6 months after the treatment by single photon emission computed tomography(SPECT). Results At 6 months, the left ventricular ejection fraction (LVEF) and 6 minute walk test (6MWT) distance increased, while the left ventricular diastolic diameter (LVDd) decreased significantly in both groups. There were no significant difference between the two groups in absolute change in the cardiac function parameters. Conclusions The present study demonstrated that autologous intracoronary PBSCT might be safe and feasible for both old and younger patients with heart failure after MI and left ventricular function is significantly improved.(J Geriatr Cardiol 2007;4:233-237.)

关键词： G-CSF stem cells transplantation myocardial infarction heart failure

An Efficient CPE Preconditioner for Cyclic Structured Matrices

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Acta Mathematica Sinica,English Series 2023年第2期39卷 257-276页

作者： Jin Jing XU Xu Deng HANG Tong xiang gu Xing Ping LIU School of Mathematics and Statistics Anhui Normal UniversityWuhu241002China Graduate School of CAEP Beijing100088China Laboratory of Computational Physics Institute of Applied Physics and Computational MathematicsBeijing100088China

A new cyclic pseudo-elimination(CPE,in brief)preconditioner,which combines the pseudoelimination(PE)technique and LU factorization together,is proposed for a kind of cyclic structured *** the case of M-matrices,some theoretical results of convergence and estimation of the condition number are *** experiments show that the CPE preconditioner performs the best with respect to the reduction of number of ***,it costs much less time than the ILUT and block Jacobi(BJ)preconditioners in a whole in all tested cases.

关键词： Cyclic structured matrix preconditioning technique cyclic structured mesh pseudo-elimination