44 results on '"YAOBIN OU"'
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2. Low Mach and Low Froude Number Limit for Vacuum Free Boundary Problem of All-time Classical Solutions of one-dimensional Compressible Navier-Stokes Equations.
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Yaobin Ou
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- 2021
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3. Hierarchical combinatorial deep learning architecture for pancreas segmentation of medical computed tomography cancer images.
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Min Fu, Wenming Wu, Xiafei Hong, Qiuhua Liu, Jialin Jiang, Yaobin Ou, Yupei Zhao, and Xinqi Gong
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- 2018
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4. Low Mach number limit of Navier-Stokes equations with large temperature variations in bounded domains
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Qiangchang Ju and Yaobin Ou
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Applied Mathematics ,General Mathematics - Published
- 2022
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5. Singular limit of planar magnetohydrodynamic equations with vacuum free boundary
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Min Liang, Yaobin Ou, and Pan Shi
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General Mathematics ,General Engineering - Published
- 2023
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6. Global axisymmetric classical solutions of full compressible magnetohydrodynamic equations with vacuum free boundary and large initial data
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Kunquan Li, Yaobin Ou, and Zilai Li
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Lagrangian and Eulerian specification of the flow field ,General Mathematics ,Mathematical analysis ,Degenerate energy levels ,Free boundary problem ,Rotational symmetry ,Boundary (topology) ,Magnetohydrodynamic drive ,Axial symmetry ,Upper and lower bounds ,Mathematics - Abstract
In this paper, the global existence of the classical solution to the vacuum free boundary problem of full compressible magnetohydrodynamic equations with large initial data and axial symmetry is studied. The solutions to the system (1.6)–(1.8) are in the class of radius-dependent solutions, i.e., independent of the axial variable and the angular variable. In particular, the expanding rate of the moving boundary is obtained. The main difficulty of this problem lies in the strong coupling of the magnetic field, velocity, temperature and the degenerate density near the free boundary. We overcome the obstacle by establishing the lower bound of the temperature by using different Lagrangian coordinates, and deriving the uniform-in-time upper and lower bounds of the Lagrangian deformation variable rx by weighted estimates, and also the uniform-in-time weighted estimates of the higher order derivatives of solutions by delicate analysis.
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- 2020
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7. Incompressible limit of isentropic magnetohydrodynamic equations with ill-prepared data in bounded domains
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Xiaoyu Gu, Yaobin Ou, and Lu Yang
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Statistical and Nonlinear Physics ,Mathematical Physics - Abstract
This paper rigorously justifies the incompressible limit of strong solutions to isentropic compressible magnetohydrodynamic equations with ill-prepared initial data in a three-dimensional bounded domain as the Mach number goes to zero. In both cases of viscous and inviscid magnetic fields, we establish a new energy functional with weight to obtain uniform estimates for strong solutions with respect to the Mach number. Then, we prove the weak convergence of a velocity and the strong convergence of a magnetic field and the divergence-free component of a velocity field, which yields the corresponding incompressible limit.
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- 2023
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8. CONVERGENCE RATE OF FULLY COMPRESSIBLE NAVIER-STOKES EQUATIONS IN THREE-DIMENSIONAL BOUNDED DOMAINS.
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MIN LIANG and YAOBIN OU
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MACH number - Abstract
For the purpose of engineering, it is important to study the convergent rates in the process of low Mach number limit. However, there are only a few results on this issue, which focus on the cases of isentropic regime or the ones without solid boundaries. In this paper, we obtain the convergence rates for the local strong solutions of the non-isentropic compressible Navier-Stokes equations with well-prepared initial data and Navier-slip boundary condition in a three-dimensional bounded domain as the Mach number vanishes. [ABSTRACT FROM AUTHOR]
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- 2023
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9. A blow-up criterion for compressible viscous heat-conductive flows
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Song, Jiang and Yaobin, Ou
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- 2010
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10. Incompressible limit of non-isentropic compressible magnetohydrodynamic equations with zero magnetic diffusivity in bounded domains
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Lu Yang and Yaobin Ou
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Physics ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,General Engineering ,General Medicine ,Péclet number ,01 natural sciences ,010101 applied mathematics ,Computational Mathematics ,symbols.namesake ,Mach number ,Bounded function ,symbols ,Initial value problem ,Boundary value problem ,Magnetohydrodynamic drive ,0101 mathematics ,Magnetic diffusivity ,Magnetohydrodynamics ,General Economics, Econometrics and Finance ,Analysis - Abstract
This paper verifies the incompressible limit of the non-isentropic compressible magnetohydrodynamic (MHD) equations without magnetic diffusion in a three-dimensional bounded C 4 -domain. The uniform estimates in both the Mach number ϵ and the Peclet number κ for the local strong solutions, which exclude the estimate of high-order derivatives of the velocity in the normal directions to the boundary, are established in a short time interval independent of ϵ and κ ( κ ≤ O ( ϵ β ) , 0 β ≤ 4 3 ), provided that the “well-prepared” initial condition for the solution and the non-slip boundary condition for the velocity are imposed.
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- 2019
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11. Global strong solutions to 1-D vacuum free boundary problem for compressible Navier–Stokes equations with variable viscosity and thermal conductivity
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Zilai Li, Yaobin Ou, and Yan Ma
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Applied Mathematics ,Mathematical analysis ,Boundary (topology) ,Boltzmann equation ,symbols.namesake ,Viscosity ,Thermal conductivity ,Jacobian matrix and determinant ,symbols ,Free boundary problem ,Compressibility ,Uniqueness ,Analysis ,Mathematics - Abstract
In this paper, we investigate the vacuum free boundary problem of one-dimensional heat-conducting compressible Navier–Stokes equations where the viscosity coefficient depends on the density, and the heat conductivity coefficient depends on the temperature, satisfying a physical assumption from the Chapman–Enskog expansion of the Boltzmann equation. The fluid connects to the vacuum continuously, thus the system is degenerate near the free boundary. The global existence and uniqueness of strong solutions for the free boundary problem are established when the initial data are large. The result is proved by using both the Lagrangian mass coordinate and the Lagrangian trajectory coordinate. An key observation is that the Jacobian between these coordinates are bounded from above and below by positive constants.
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- 2019
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12. On globally large smooth solutions of full compressible Navier–Stokes equations with moving boundary and temperature-dependent heat-conductivity
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Yaobin Ou
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Physics ,Applied Mathematics ,Degenerate energy levels ,Mathematical analysis ,General Engineering ,Symmetry in biology ,Boundary (topology) ,General Medicine ,Upper and lower bounds ,Computational Mathematics ,Nonlinear system ,Compressibility ,Free boundary problem ,Uniqueness ,General Economics, Econometrics and Finance ,Analysis - Abstract
The global existence and uniqueness of smooth solution to the vacuum free boundary problem of full compressible Navier–Stokes equations with large initial data and radial symmetry is established in this paper, when the fluid connects to vacuum continuously. The main difficulty lies in the fact that, the system is strongly nonlinear with unknown boundary variables, and degenerate near the free boundary separating the fluid and vacuum, thus general theory does not apply to this case. To overcome this trouble, we establish the point-wise estimates on the upper and lower bounds of the deformation variable η x , the refined estimate for the temperature, and also the uniform-in-time weighted energy estimates for the solutions with high regularity, by careful analysis. Moreover, the expanding rate of the free interface is also proved. The main ingredient of this paper is that the high regularity of the solution is always up to the free boundary. Previous results are only for weak solutions, or the case that the fluids connect to the vacuum with a jump. The assumption on the heat conductivity coefficient κ ≈ 1 + θ q , q ≥ 2 is also improved to be q > 0 .
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- 2022
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13. Global wellposedness of vacuum free boundary problem of isentropic compressible magnetohydrodynamic equations with axisymmetry
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Yaobin Ou and Kunquan Li
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Physics ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,Boundary (topology) ,01 natural sciences ,Symmetry (physics) ,010101 applied mathematics ,Nonlinear system ,Singularity ,Free boundary problem ,Compressibility ,Discrete Mathematics and Combinatorics ,0101 mathematics ,Adiabatic process ,Axial symmetry - Abstract
In this paper, we prove the global existence of the strong solutions to the vacuum free boundary problem of isentropic compressible magnetohydrodynamic equations with small initial data and axial symmetry, where the solutions are independent of the axial variable and the angular variable. The solutions capture the precise physical behavior that the sound speed is \begin{document}$ C^{1/2} $\end{document}-Hölder continuous across the vacuum boundary provided that the adiabatic exponent \begin{document}$ \gamma\in(1, 2) $\end{document}. The main difficulties of this problem lie in the singularity at the symmetry axis, the degeneracy of the system near the free boundary and the strong coupling of the magnetic field and the velocity. We overcome the obstacles by constructing some new weighted nonlinear functionals (involving both lower-order and higher-order derivatives) and establishing the uniform-in-time weighted energy estimates of solutions by delicate analysis, in which the balance of pressure and self-gravitation, and the dissipation of velocity are crucial.
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- 2022
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14. Bilibili, TikTok, and YouTube as sources of information on gastric cancer: assessment and analysis of the content and quality
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Menghui Wang, Nan Yao, Jianming Wang, Wenjuan Chen, Yaobin Ouyang, and Chuan Xie
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Gastric cancer ,Quality ,Online video ,The public ,Social media ,Public aspects of medicine ,RA1-1270 - Abstract
Abstract Background Gastric cancer has attracted widespread attention on social media due to its high incidence and severity. The Bilibili, TikTok, and YouTube video-sharing platforms have received considerable interest among general health consumers. Nevertheless, it remains unclear whether the information in videos on these platforms is of satisfactory content and quality. Methods A total of 300 eligible videos related to gastric cancer were screened from three video-sharing platforms, Bilibili, TikTok, and YouTube, for assessment and analysis. First, the basic information presented in the videos was recorded. Next, we identified the source and content type of each video. Then, the Global Quality Scale (GQS), Journal of the American Medical Association (JAMA), and Modified DISCERN were used to assess the educational content and quality of each video. A comparative analysis was undertaken of the videos procured from these three sources. Results We identified six categories of uploaders of the 300 videos: 159 videos (53%) were uploaded by health professionals, 21 videos (7%) by users in science communications, 29 videos (9.67%) by general users, 27 videos (9%) from news agencies, 63 videos (12%) by nonprofit organizations, and one video (0.33%) by a for-profit organization. In terms of the content types of the 300 videos, we identified five distinct categories. There were 48 videos (16%) on early signals, 12 videos (4%) on late symptoms, 40 videos (13.33%) on etiologies and causations, 160 videos (53.33%) on scientific introductions, and 40 videos (13.33%) on treatment methods. The overall quality of the videos was evaluated by the GQS, JAMA, and Modified DISCERN and was found to be medium, with scores of 2.6/5, 2.41/4, and 2.71/5 points, respectively. Conclusions This innovative study demonstrates that videos on social media platforms can help the public learn about early signals, late symptoms, treatment methods, etiologies and causations, and scientific introductions of gastric cancer. However, both the content and quality of uploaded recordings are inadequate currently. More efforts should be made to enhance the content and quality of videos on gastric cancer and to increase public awareness.
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- 2024
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15. Hierarchical combinatorial deep learning architecture for pancreas segmentation of medical computed tomography cancer images
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Jialin Jiang, Min Fu, Yupei Zhao, Wenming Wu, Yaobin Ou, Qiuhua Liu, Xiafei Hong, and Xinqi Gong
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Similarity (geometry) ,Single object segmentation ,Computer science ,Pipeline (computing) ,02 engineering and technology ,Field (computer science) ,Edge detection ,030218 nuclear medicine & medical imaging ,03 medical and health sciences ,0302 clinical medicine ,Deep Learning ,Structural Biology ,0202 electrical engineering, electronic engineering, information engineering ,Image Processing, Computer-Assisted ,Humans ,Segmentation ,Molecular Biology ,lcsh:QH301-705.5 ,Pancreas ,business.industry ,Applied Mathematics ,Deep learning ,Research ,Pattern recognition ,Object (computer science) ,Computer Science Applications ,Pancreatic Neoplasms ,lcsh:Biology (General) ,Feature (computer vision) ,Modeling and Simulation ,Case-Control Studies ,Multi-layer up-sampling structure ,020201 artificial intelligence & image processing ,Pancreas segmentation ,Artificial intelligence ,business ,Tomography, X-Ray Computed - Abstract
Background Efficient computational recognition and segmentation of target organ from medical images are foundational in diagnosis and treatment, especially about pancreas cancer. In practice, the diversity in appearance of pancreas and organs in abdomen, makes detailed texture information of objects important in segmentation algorithm. According to our observations, however, the structures of previous networks, such as the Richer Feature Convolutional Network (RCF), are too coarse to segment the object (pancreas) accurately, especially the edge. Method In this paper, we extend the RCF, proposed to the field of edge detection, for the challenging pancreas segmentation, and put forward a novel pancreas segmentation network. By employing multi-layer up-sampling structure replacing the simple up-sampling operation in all stages, the proposed network fully considers the multi-scale detailed contexture information of object (pancreas) to perform per-pixel segmentation. Additionally, using the CT scans, we supply and train our network, thus get an effective pipeline. Result Working with our pipeline with multi-layer up-sampling model, we achieve better performance than RCF in the task of single object (pancreas) segmentation. Besides, combining with multi scale input, we achieve the 76.36% DSC (Dice Similarity Coefficient) value in testing data. Conclusion The results of our experiments show that our advanced model works better than previous networks in our dataset. On the other words, it has better ability in catching detailed contexture information. Therefore, our new single object segmentation model has practical meaning in computational automatic diagnosis.
- Published
- 2018
16. Research trends on nanomaterials in gastric cancer: a bibliometric analysis from 2004 to 2023
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Li-Xiang Ling, Yaobin Ouyang, and Yi Hu
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Bibliometric analysis ,Gastric cancer ,Nanomaterial ,Research trend ,Biotechnology ,TP248.13-248.65 ,Medical technology ,R855-855.5 - Abstract
Abstract Background Gastric cancer is one of the leading causes of cancer-related deaths worldwide. In recent years, an increasing number of studies aimed at designing and developing nanomaterials for use in diagnosing and treating gastric cancer have been conducted. In this study, we aimed to comprehensively assess the current status and trends of the research on the application of nanomaterials in gastric cancer through a bibliometric analysis. Methods Studies focusing on nanomaterials and gastric cancer were retrieved from the Web of Science Core Collection database and relevant articles were selected for inclusion in the study according to the inclusion criteria. Bibliometric and visual analysis of the included publications was performed using VOSviewer and CiteSpace. Results A total of 793 studies were included. An increase in annual publications was observed from 2004 to 2023. China, Iran and the USA were the dominant countries in this field, accounting for 66.1%, 11.5% and 7.2% of publications, respectively. Shanghai Jiao Tong University and Cui DX were the most influential institution and author, respectively. The International Journal of Nanomedicine was the most prolific journal; Biomaterials was the most cited and most cocited journal. Nanomaterial-related drug delivery and anticancer mechanisms were found to be the most widely researched aspects, and green synthesis and anticancer mechanisms are recent research hotspots. Conclusion In this study, we summarized the characteristics of publications and identified the most influential countries, institutions, authors, journals, hot topics and trends regarding the application of nanomaterials in gastric cancer. Graphical Abstract
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- 2023
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17. Global strong solutions to the vacuum free boundary problem for compressible Navier–Stokes equations with degenerate viscosity and gravity force
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Yaobin Ou and Huihui Zeng
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Physics ,Viscosity ,Applied Mathematics ,Uniform convergence ,Degenerate energy levels ,Mathematical analysis ,Compressibility ,Vacuum permeability ,Free boundary problem ,Boundary layer thickness ,Compressible flow ,Analysis - Abstract
For the vacuum free boundary problem of the one-dimensional compressible Navier–Stokes equations with the density dependent viscosity coefficient and gravity force, the global existence of the strong solution is proved, which is shown to converge to the steady solution with the same total mass when the initial datum is a small perturbation of the steady solution only at the basic level. The key is to establish the global-in-time regularity uniformly up to the vacuum boundary, which ensures the large time asymptotic uniform convergence of the evolving vacuum boundary, density and velocity to those of the steady solution with detailed convergence rates. Compared with previous studies, the novelty of this paper is the regularity of global solutions for the vacuum free boundary problems in viscous compressible fluids when the viscosity coefficient is not constant but degenerate.
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- 2015
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18. Incompressible limit of full compressible magnetohydrodynamic equations with well-prepared data in 3-D bounded domains
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Wenqian Cui, Dandan Ren, and Yaobin Ou
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Applied Mathematics ,Mathematical analysis ,Polytropic process ,Domain (mathematical analysis) ,Physics::Fluid Dynamics ,symbols.namesake ,Mach number ,Physics::Plasma Physics ,Bounded function ,Convergence (routing) ,Compressibility ,symbols ,Limit (mathematics) ,Magnetohydrodynamic drive ,Analysis ,Mathematics - Abstract
This paper studies the singular limits of the non-isentropic compressible magnetohydrodynamic equations for viscous and heat-conductive ideal polytropic flows with magnetic diffusions in a three-dimensional bounded domain as the Mach number goes to zero. Provided that the initial data are well-prepared, we establish the uniform estimates with respect to the Mach number, which gives the convergence from the full compressible magnetohydrodynamic equations to isentropic incompressible magnetohydrodynamic equations.
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- 2015
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19. YAP and β-catenin cooperate to drive H. pylori-induced gastric tumorigenesis
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Nianshuang Li, Xinbo Xu, Yuan Zhan, Xiao Fei, Yaobin Ouyang, Pan Zheng, Yanan Zhou, Cong He, Chuan Xie, Yi Hu, Junbo Hong, Nonghua Lu, Zhongming Ge, and Yin Zhu
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H. pylori ,YAP ,β-catenin ,gastric carcinogenesis ,Diseases of the digestive system. Gastroenterology ,RC799-869 - Abstract
ABSTRACTH. pylori infection is the strongest known risk factor for gastric carcinoma. The activation of the yes-associated protein 1 (YAP) and β-catenin pathways has been associated with multiple tumor types. In this study, we investigated the crosstalk between the YAP and β-catenin pathways in H. pylori-associated gastric tumorigenesis. Immunohistochemical analysis of YAP and β-catenin expression was performed in human gastric cancer tissues. The small molecules Super-TDU and KYA1797K, pharmacological inhibitors of YAP and β-catenin, respectively, were used to investigate the role of these signaling pathways in H. pylori-induced gastric carcinogenesis in murine models of infection. The common downstream targets of YAP and β-catenin signaling were evaluated by RNA sequencing (RNA-seq). Western blot, immunofluorescence, luciferase, RT-PCR, immunoprecipitation, cell counting kit-8 (CCK8), EdU and spheroid assays were used. H. pylori infection promoted YAP and β-catenin nuclear accumulation and transcriptional activity in gastric epithelial cells and transgenic insulin–gastrin (INS-GAS) mice, whereas silencing of both YAP and β-catenin synergistically inhibited H. pylori-induced cell proliferation and expansion. In addition, YAP was found to directly interact with β-catenin and knockdown of YAP suppressed H. pylori-induced nuclear translocation of β-catenin. Moreover, downstream genes caudal-type homeobox 2 (CDX2), leucine-rich repeat containing G protein-coupled receptor 5 (LGR5) and RuvB like AAA ATPase 1 (RUVBL1) were shared by both YAP and β-catenin signaling. Furthermore, treatment with the YAP inhibitor Super-TDU or β-catenin inhibitor KYA1797A significantly alleviated gastric inflammation and epithelial DNA damage in H. pylori-infected mice. Finally, the elevation of gastric YAP was positively correlated with β-catenin expression in human gastric cancer tissues. These findings indicate that YAP and β-catenin synergistically promote H. pylori-induced gastric carcinogenesis via their physical interaction and reveal that CDX2, LGR5 and RUVBL1 are the downstream genes shared by both the YAP and β-catenin signaling pathways, and potentially contribute to H. pylori pathogenesis.
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- 2023
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20. Low Mach number limit of full Navier–Stokes equations in a 3D bounded domain
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Yaobin Ou, Changsheng Dou, and Song Jiang
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Hypersonic speed ,Applied Mathematics ,Mathematical analysis ,Mathematics::Analysis of PDEs ,Non-dimensionalization and scaling of the Navier–Stokes equations ,Mach wave ,Physics::Fluid Dynamics ,symbols.namesake ,Mach number ,Pressure-correction method ,Hagen–Poiseuille flow from the Navier–Stokes equations ,symbols ,Reynolds-averaged Navier–Stokes equations ,Navier–Stokes equations ,Analysis ,Mathematics - Abstract
This paper studies the low Mach number limit of the full compressible Navier–Stokes equations in a three-dimensional bounded domain where the velocity field and the temperature satisfy the slip boundary conditions and the Neumann boundary condition, respectively. The uniform estimates in the Mach number for the strong solutions are derived in a short time interval, provided that the initial density and temperature are close to the constant states and satisfy the “bounded derivative conditions”. Thus the solutions of the full compressible Navier–Stokes equations converge to the one of the isentropic incompressible Navier–Stokes equations, as the Mach number vanishes.
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- 2015
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21. Incompressible limit of global strong solutions to 3-D barotropic Navier–Stokes equations with well-prepared initial data and Navier's slip boundary conditions
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Dandan Ren and Yaobin Ou
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Applied Mathematics ,Mathematical analysis ,Slip (materials science) ,Physics::Fluid Dynamics ,Strong solutions ,symbols.namesake ,Mach number ,Barotropic fluid ,Bounded function ,Compressibility ,symbols ,Boundary value problem ,Navier–Stokes equations ,Analysis ,Mathematics - Abstract
This paper studies the incompressible limit of global strong solutions to the three-dimensional barotropic Navier–Stokes equations associated with Navier's slip boundary conditions, provided that the initial data are sufficiently small, and “well-prepared” in the sense that the time derivatives, up to first order, of solutions are bounded initially. The main idea is to derive a differential inequality with decay, so that the estimates are bounded uniformly both in the Mach number ϵ ∈ ( 0 , ϵ 0 ] (for some ϵ 0 > 0 ) and the time t ∈ [ 0 , + ∞ ) .
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- 2014
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22. Uniform existence of the 1-D full equations for a thermo-radiative electromagnetic fluid
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Jishan Fan and Yaobin Ou
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Physics ,Electromagnetic wave equation ,Displacement current ,Applied Mathematics ,Bounded function ,Mathematical analysis ,Radiative transfer ,Zero (complex analysis) ,Inhomogeneous electromagnetic wave equation ,Dielectric ,Magnetohydrodynamic drive ,Physics::Classical Physics ,Analysis - Abstract
In this paper, we prove the uniform estimates with respect to the dielectric constant and the global-in-time existence of the 1-D full equations for a thermo-radiative electromagnetic fluid in a bounded interval without vacuum. We establish the uniform estimates in the dielectric constant, which gives that, as the dielectric constant tends to zero, the solutions to the 1-D full thermo-radiative electromagnetic equations will converge to the one for the 1-D full magnetohydrodynamic equations with thermo-radiations and magnetic diffusions. This approximation is usually referred to as the magnetohydrodynamic approximation, where the displacement current is not taken into account.
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- 2014
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23. Strong solutions to an Oldroyd-B model with slip boundary conditions via incompressible limit
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Yaobin Ou and Dandan Ren
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General Mathematics ,Mathematical analysis ,Mathematics::Analysis of PDEs ,General Engineering ,Slip (materials science) ,Viscoelasticity ,Physics::Fluid Dynamics ,Strong solutions ,symbols.namesake ,Classical mechanics ,Mach number ,Bounded function ,Compressibility ,symbols ,Oldroyd-B model ,Boundary value problem ,Mathematics - Abstract
In this paper, we establish the local existence of strong solutions to an Oldroyd-B model for the incompressible viscoelastic fluids in a bounded domain , via the incompressible limit. The main idea is to derive the uniform estimates with respect to the Mach number for the linearized system of compressible Oldroyd equations. Copyright © 2014 John Wiley & Sons, Ltd.
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- 2014
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24. Incompressible limit of all-time solutions to 3-D full Navier–Stokes equations for perfect gas with well-prepared initial condition
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Dandan Ren and Yaobin Ou
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Applied Mathematics ,General Mathematics ,010102 general mathematics ,Mathematical analysis ,Mathematics::Analysis of PDEs ,General Physics and Astronomy ,Perfect gas ,01 natural sciences ,Physics::Fluid Dynamics ,symbols.namesake ,Mach number ,Dirichlet boundary condition ,0103 physical sciences ,Compressibility ,symbols ,Initial value problem ,Vector field ,010307 mathematical physics ,Boundary value problem ,0101 mathematics ,Navier–Stokes equations ,Mathematics - Abstract
In this paper, we prove the incompressible limit of all-time strong solutions to the three-dimensional full compressible Navier–Stokes equations. Here the velocity field and temperature satisfy the Dirichlet boundary condition and convective boundary condition, respectively. The uniform estimates in both the Mach number $${\epsilon\in(0,\overline{\epsilon}]}$$ and time $${t\in[0,\infty)}$$ are established by deriving a differential inequality with decay property, where $${\overline{\epsilon} \in(0,1]}$$ is a constant. Based on these uniform estimates, the global solution of full compressible Navier–Stokes equations with “well-prepared” initial conditions converges to the one of isentropic incompressible Navier–Stokes equations as the Mach number goes to zero.
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- 2016
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25. Incompressible limit of the non-isentropic Navier–Stokes equations with well-prepared initial data in three-dimensional bounded domains
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Yaobin Ou and Song Jiang
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Mathematics(all) ,Mach number ,General Mathematics ,Applied Mathematics ,Mathematical analysis ,Mathematics::Analysis of PDEs ,Boundary (topology) ,Polytropic process ,Physics::Fluid Dynamics ,symbols.namesake ,Navier–Stokes equations ,Pressure-correction method ,Bounded function ,symbols ,Compressibility ,Limit (mathematics) ,Incompressible limit ,Navier-Stokes equations ,Mathematics - Abstract
This paper studies the incompressible limit of the non-isentropic Navier–Stokes equations for viscous polytropic flows with zero thermal coefficient in three-dimensional bounded C 4 -domains. The uniform estimates in the Mach number, which exclude the estimate of high-order derivatives of the velocity in the normal directions to the boundary, are established within a short time interval independent of Mach number ϵ ∈ ( 0 , 1 ] , provided that the initial data are well-prepared.
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- 2011
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26. Large time behaviors of strong solutions to magnetohydrodynamic equations with free boundary and degenerate viscosity
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Pan Shi, Peter Wittwer, and Yaobin Ou
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Physics ,Steady state ,010102 general mathematics ,Mathematical analysis ,Degenerate energy levels ,Boundary (topology) ,Statistical and Nonlinear Physics ,01 natural sciences ,Upper and lower bounds ,010101 applied mathematics ,Viscosity ,Free boundary problem ,Magnetohydrodynamic drive ,0101 mathematics ,Degeneracy (mathematics) ,Mathematical Physics - Abstract
In this paper, we establish the local, global existence and large-time behaviors of strong solutions to the free boundary problem of the planar magnetohydrodynamic equations with degenerate viscosity coefficient. Only the initial energy at the basic level is required to be small. The main difficulties are the degeneracy of the system near the free boundary and the strong coupling of the magnetic field and the velocity. We overcome the trouble by deriving the point-wise upper and lower bounds of the deformation variable uniformly in time and spatial variables and setting up the uniform-in-time weights energy estimates of solutions via singular multipliers. In contrast to previous works, the density is not required to be bounded from below and the viscosity coefficient is not a constant but degenerate; moreover, sharp convergent rates toward the steady state of the solutions are obtained.
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- 2018
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27. A blow-up criterion for compressible viscous heat-conductive flows
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Yaobin Ou, Jishan Fan, and Song Jiang
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Ideal (set theory) ,Applied Mathematics ,010102 general mathematics ,Mathematics::Analysis of PDEs ,Mechanics ,01 natural sciences ,Domain (mathematical analysis) ,Physics::Fluid Dynamics ,010101 applied mathematics ,Strong solutions ,Classical mechanics ,Bounded function ,Compressibility ,Boundary value problem ,0101 mathematics ,Electrical conductor ,Mathematical Physics ,Analysis ,Mathematics - Abstract
We study an initial boundary value problem for the three-dimensional Navier–Stokes equations of viscous heat-conductive fluids in a bounded smooth domain. We establish a blow-up criterion for the local strong solutions in terms of the temperature and the gradient of velocity only, similar to the Beale–Kato–Majda criterion for ideal incompressible flows.
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- 2010
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28. Incompressible limits of the Navier–Stokes equations for all time
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Yaobin Ou
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Hypersonic speed ,Mach number ,Applied Mathematics ,Mathematical analysis ,Non-dimensionalization and scaling of the Navier–Stokes equations ,Euler equations ,Physics::Fluid Dynamics ,Navier–Stokes equations ,symbols.namesake ,Pressure-correction method ,Hagen–Poiseuille flow from the Navier–Stokes equations ,symbols ,Incompressible limit ,Reynolds-averaged Navier–Stokes equations ,Analysis ,Mathematics - Abstract
We study the asymptotic behaviors of the regular solutions to the compressible Navier–Stokes equations for “well-prepared” initial data for all time as the Mach number tends to zero, by deriving a differential inequality with certain decay property. The estimates obtained in this paper are uniform both in time and Mach number.
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- 2009
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29. Low Mach number limit for the non-isentropic Navier–Stokes equations
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Yaobin Ou
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Hypersonic speed ,Applied Mathematics ,Mathematical analysis ,Non-dimensionalization and scaling of the Navier–Stokes equations ,Mach wave ,Physics::Fluid Dynamics ,symbols.namesake ,Mach number ,symbols ,Compressibility ,Limit (mathematics) ,Navier–Stokes equations ,Stokes number ,Analysis ,Mathematics - Abstract
We study the low Mach number limit of the local in time solutions to the compressible Navier–Stokes equations with zero heat conductivity coefficient as the Mach number tends to zero. A uniform existence result for the one-dimensional initial–boundary value problem is proved provided that the initial data are “well-prepared” in the sense that the temporal derivatives up to order two are bounded initially.
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- 2009
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30. Correction: Helicobacter pylori CagA promotes epithelial mesenchymal transition in gastric carcinogenesis via triggering oncogenic YAP pathway
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Nianshuang Li, Yan Feng, Yi Hu, Cong He, Chuan Xie, Yaobin Ouyang, Stephen C. Artim, Deqiang Huang, Yin Zhu, Zhijun Luo, Zhongming Ge, and Nonghua Lu
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Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Published
- 2023
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31. Helicobacter pylori infection activates Wnt/β-catenin pathway to promote the occurrence of gastritis by upregulating ASCL1 and AQP5
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Wei Zuo, Hui Yang, Nianshuang Li, Yaobin Ouyang, Xinbo Xu, and Junbo Hong
- Subjects
Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 ,Cytology ,QH573-671 - Abstract
Abstract Helicobacter pylori (H. pylori) infection is a well-recognized contributing factor to gastritis, but the underlying mechanisms remain to be established. It is interesting to note that AQP5 was predicted to be highly expressed in intestinal metaplasia (IM) based on H. pylori infection-related microarray data, and the transcription factor ASCL1 was bioinformatically predicted to associate with AQP5. Therefore, the purpose of this study is to evaluate the mechanistic significance of ASCL1 and AQP5 in H. pylori infection of gastritis. Gastritis mouse models were established by H. pylori infection, followed by determination of AQP5 and ASCL1 in gastric mucosa. Besides, the effects of AQP5 on H. pylori-induced gastritis were explored using AQP5−/− mice. It was observed that H. pylori infection elevated expression of AQP5 and ASCL1 in gastric mucosa and gastric epithelial cells (GECs). H. pylori induced AQP5 expression by regulating ASCL1 and activated WNT/β-catenin signaling pathway in GECs. It was also found that AQP5 knockdown suppressed inflammatory response and apoptosis in H. pylori-infected mice. Moreover, H. pylori infection-elevated ASCL1 and AQP5 expression promoted apoptosis and inflammation in GECs. Taken together, the key findings of the present study demonstrate that H. pylori infection activated WNT/β-catenin signaling pathway by upregulating ASCL1/AQP5 to induce gastritis.
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- 2022
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32. Research trends on the relationship between gut microbiota and colorectal cancer: A bibliometric analysis
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Weigen Wu, Yaobin Ouyang, Pan Zheng, Xinbo Xu, Cong He, Chuan Xie, Junbo Hong, Nonghua Lu, Yin Zhu, and Nianshuang Li
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colorectal cancer ,gut microbiota ,bibliometric analysis ,research trends ,hot spots ,Microbiology ,QR1-502 - Abstract
BackgroundColorectal cancer (CRC)is the third most common cancer in the world and the second leading cause of cancer-related deaths, and over the past two decades, many of these researchers have provided a substantial amount of important information on the role of gut microbes in the development and progression of CRC. A causal relationship between the presence of specific microorganisms and CRC development has also been validated. Although a large number of papers related to this area have been published, no bibliometric study has been conducted to review the current state of research in this area and to highlight the research trends and hotspots in this area. This study aims to analyze the current status and future research trends of gut microbiota and CRC through bibliometric analysis.MethodsPublications from 2001 to 2022 were retrieved from the Web of Science Core Collection database and screened according to inclusion criteria. VOSviewer and CiteSpace software were used to visualize the research trends in this field, including the analysis of title, country, institution, author, number of publications, year of publication, number of citations, journal, and H-index.ResultsA total of 863 studies were eventually identified, and the articles retrieved were cited an average of 44.85 times each. The number of publications on this topic has been increased steadily since 2011. China and the USA have made the largest contribution in the field. FRONTIERS IN MICROBIOLOGY is the top productive journal with 26 papers, and Gut journal has the highest average citation (167.23). Shanghai Jiao Tong University is the most contributive institution. Professor Yu J, Sung, Joseph J. Y and Fang JY are the most productive authors in this field. Keyword co-occurrence analysis showed that the terms of “Gut Microbiota”, “Colorectal Cancer”, “Inflammation”, “Probiotic” and “Fusobacterium Nucleatum” were the most frequent, which revealed the research hotpots and trends in this field.ConclusionsThere has been a growing number of publications over the past two decades according to the global trends. China and the USA still maintained the leading position in this field. However, collaboration between institutions needs to be strengthened. It’s commended to pay attention to the latest hotspots, such as “F. nucleatum” and “probiotics”. This bibliometric analysis evaluates the scope and trends of gut microbiota and CRC, providing a useful perspective on current research and future directions for studying the link between the gut microbiota and CRC.
- Published
- 2023
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33. A positive feedback loop of the TAZ/β-catenin axis promotes Helicobacter pylori-associated gastric carcinogenesis
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Xinbo Xu, Chunxi Shu, Xidong Wu, Yaobin Ouyang, Hong Cheng, Yanan Zhou, Huan Wang, Cong He, Chuan Xie, Xingxing He, Junbo Hong, Nonghua Lu, Zhongming Ge, Yin Zhu, and Nianshuang Li
- Subjects
Helicobacter Pylori ,CagA ,TAZ ,β-catenin ,gastric carcinogenesis ,Microbiology ,QR1-502 - Abstract
BackgroundHelicobacter pylori infection is the strongest known risk factor for gastric cancer. The Hippo signaling pathway controls organ size and maintains tissue homeostasis by coordinately regulating cell growth and proliferation. Here, we demonstrate the interactive role of TAZ, the transcriptional coactivator of the Hippo pathway, and beta-catenin in promoting the pathogenesis of H. pylori infection.MethodsTAZ expression was evaluated in human gastric tissues and H. pylori-infected insulin–gastrin (INS-GAS) mice. Western blot, immunofluorescence, immunohistochemistry, and RT–PCR assays were performed. Coimmunoprecipitation was performed to examine the interaction between TAZ and β-catenin. TAZ and β-catenin were silenced using small interfering RNAs. HA-β-catenin and Flag-TAZ were constructed.ResultsIncreased TAZ was noted in human gastric cancer tissues compared to chronic gastritis tissues and in H. pylori-positive gastritis tissues compared to H. pylori-negative gastritis tissues. In addition, H. pylori infection induced TAZ expression and nuclear accumulation in the gastric tissue of INS-GAS mice and cultured gastric epithelial cells, which was dependent on the virulence factor CagA. Moreover, TAZ or β-catenin knockdown significantly suppressed H. pylori infection-induced cell growth, survival, and invasion. Furthermore, the interactive regulation of TAZ and β-catenin activation was revealed. Finally, β-catenin was required for H. pylori-induced TAZ activation.ConclusionThese findings suggest the existence of a positive feedback loop of activation between TAZ and β-catenin that could play an important role in CagA+ H. pylori infection-induced gastric carcinogenesis. TAZ inhibition represents a potential target for the prevention of H. pylori infection-associated gastric cancer.
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- 2022
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34. The vanishing viscosity method for the sensitivity analysis of an optimal control problem of conservation laws in the presence of shocks
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Peicheng Zhu and Yaobin Ou
- Subjects
Conservation law ,Applied Mathematics ,Mathematical analysis ,General Engineering ,Scalar (physics) ,General Medicine ,Optimal control ,Method of matched asymptotic expansions ,Computational Mathematics ,Viscosity ,Sensitivity ,Vanishing viscosity limit ,Adjoint equation ,Inviscid flow ,Limit (mathematics) ,General Economics, Econometrics and Finance ,Shocks ,Analysis ,Mathematics ,Conservation laws - Abstract
In this article we study, by the vanishing viscosity method, the sensitivity analysis of an optimal control problem for 1-D scalar conservation laws in the presence of shocks. It is reduced to investigate the vanishing viscosity limit for the nonlinear conservation law, the corresponding linearized equation and its adjoint equation, respectively. We employ the method of matched asymptotic expansions to construct approximate solutions to those equations. It is then proved that the approximate solutions, respectively, satisfy those viscous equations in the asymptotic sense, and converge to the solutions of the corresponding inviscid problems with certain convergent rates. A new equation for the variation of shock positions is derived. It is also discussed how to identify descent directions to find the minimizer of the viscous optimal control problem in the quasi-shock case.
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- 2013
35. Spherically symmetric solutions to a model for phase transitions driven by configurational forces
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Peicheng Zhu and Yaobin Ou
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Physics ,Phase transition ,Partial differential equation ,010102 general mathematics ,Mathematical analysis ,Linear elasticity ,Statistical and Nonlinear Physics ,Dynamical Systems (math.DS) ,01 natural sciences ,Parabolic partial differential equation ,010101 applied mathematics ,Nonlinear system ,35K55, 74E15 ,Regularization (physics) ,FOS: Mathematics ,Sharp interface ,Boundary value problem ,0101 mathematics ,Mathematics - Dynamical Systems ,Mathematical Physics - Abstract
We prove the global in time existence of spherically symmetric solutions to an initial-boundary value problem for a system of partial differential equations, which consists of the equations of linear elasticity and a nonlinear, non-uniformly parabolic equation of second order. The problem models the behavior in time of materials in which martensitic phase transitions, driven by configurational forces, take place, and can be considered to be a regularization of the corresponding sharp interface model. By assuming that the solutions are spherically symmetric, we reduce the original multidimensional problem to the one in one space dimension, then prove the existence of spherically symmetric solutions. Our proof is valid due to the essential feature that the reduced problem is one space dimensional., 25 pages
- Published
- 2011
36. Low Mach number limit of viscous polytropic fluid flows
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Yaobin Ou
- Subjects
Mach number ,Applied Mathematics ,010102 general mathematics ,Mathematical analysis ,Mathematics::Analysis of PDEs ,Slip (materials science) ,Polytropic process ,Singular limit ,Thermal coefficient ,01 natural sciences ,Physics::Fluid Dynamics ,010101 applied mathematics ,Navier–Stokes equations ,symbols.namesake ,Bounded function ,symbols ,Non-isentropic ,Boundary value problem ,Navier-Stokes equations ,0101 mathematics ,Analysis ,Mathematics - Abstract
This paper studies the singular limit of the non-isentropic Navier–Stokes equations with zero thermal coefficient in a two-dimensional bounded domain as the Mach number goes to zero. A uniform existence result is obtained in a time interval independent of the Mach number, provided that the initial data satisfy the “bounded derivative conditions”, that is, the time derivatives up to order two are bounded initially, and Navierʼs slip boundary condition is imposed.
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- 2011
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37. Research trends on clinical fecal microbiota transplantation: A biliometric analysis from 2001 to 2021
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Yu Li, Yaobin Ouyang, and Cong He
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fecal microbiota transplantation ,research trends ,CiteSpace ,VOSviewer ,bibliometric analysis ,Immunologic diseases. Allergy ,RC581-607 - Abstract
BackgroundNumerous studies on fecal microbiota transplantation (FMT) have been conducted in the past two decades. We aimed to assess the research trends and hotspots in the field of FMT through a quantitative method.Materials and MethodsThe clinical studies of FMT published from 2001 to 2021 were extracted from the Web of Science database. We analyzed the countries, institutions, authors, and keywords of these articles and visually illustrated using VOSviewer and CiteSpace software. The current application of FMT in clinical practice, including indications, efficacy, adverse events, as well as its methodology, such as donor, delivery route, were also evaluated.ResultsA total of 227 records were finally identified. The number and rate of annual publications increased gradually. The USA ranked highest in the number of publications. Harvard University was the most influential institution, and Digestive Diseases and Sciences was the most productive journal. Kassam Zain published the most papers, and the high-frequency keywords were mainly related to diseases and techniques. Healthy donors were the most widely used donors, and frozen stool had the highest frequency of use. The predominant delivery route was endoscopy followed by oral capsules and enema. FMT was most frequently performed for the treatment of recurrent Clostridium Difficile Infection. The overall efficacy of FMT was 76.88%, and the incidence of minor and severe adverse events were 11.63% and 1.59%, respectively.ConclusionsThis study delineated a comprehensive landscape of the advancement in FMT field. Although in its infancy, FMT is a burgeoning option for the treatment of a variety of diseases associated with gut dysbiosis. To improve the efficacy and reduce adverse events, future studies are warranted to optimize the methodology of FMT.
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- 2022
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38. GLOBAL CLASSICAL SOLUTIONS TO THE FREE BOUNDARY PROBLEM OF PLANAR FULL MAGNETOHYDRODYNAMIC EQUATIONS WITH LARGE INITIAL DA.
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YAOBIN OU and PAN SHI
- Subjects
MAGNETOHYDRODYNAMICS ,DATA ,VACUUM ,DENSITY ,MATHEMATICAL constants - Abstract
The free boundary problem of planar full compressible magneto-hydrodynamic equations with large initial data is studied in this paper, when the initial density connects to vacuum smoothly. The global existence and uniqueness of classical solutions are established, and the expanding rate of the free interface is shown. Using the method of Lagrangian particle path, we derive some L
∞ estimates and weighted energy estimates, which lead to the global existence of classical solutions. The main difficulty of this problem is the degeneracy of the system near the free boundary, while previous results (cf. [4, 30]) require that the density is bounded from below by a positive constant. [ABSTRACT FROM AUTHOR]- Published
- 2017
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39. Inhibition of autophagy aggravates DNA damage response and gastric tumorigenesis via Rad51 ubiquitination in response to H. pylori infection
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Chuan Xie, Nianshuang Li, Huan Wang, Cong He, Yi Hu, Chao Peng, Yaobin Ouyang, Dejie Wang, Yong Xie, Jiang Chen, Xu Shu, Yin Zhu, and Nonghua Lu
- Subjects
h. pylori ,dna damage ,autophagy ,p62 ,rad51 ,gastric carcinogenesis ,Diseases of the digestive system. Gastroenterology ,RC799-869 - Abstract
Helicobacter pylori (H. pylori) infection is the strongest known risk factor for the development of gastric cancer. DNA damage response (DDR) and autophagy play key roles in tumorigenic transformation. However, it remains unclear how H. pylori modulate DDR and autophagy in gastric carcinogenesis. Here we report that H. pylori infection promotes DNA damage via suppression of Rad51 expression through inhibition of autophagy and accumulation of p62 in gastric carcinogenesis. We find that H. pylori activated DNA damage pathway in concert with downregulation of repair protein Rad51 in gastric cells, C57BL/6 mice and Mongolian gerbils. In addition, autophagy was increased early and then decreased gradually during the duration of H. pylori infection in vitro in a CagA-dependent manner. Moreover, loss of autophagy led to promotion of DNA damage in H. pylori-infected cells. Furthermore, knockdown of autophagic substrate p62 upregulated Rad51 expression, and p62 promoted Rad51 ubiquitination via the direct interaction of its UBA domain. Finally, H. pylori infection was associated with elevated levels of p62 in gastric intestinal metaplasia and decreased levels of Rad51 in dysplasia compared to their H. pylori- counterparts. Our findings provide a novel mechanism into the linkage of H. pylori infection, autophagy, DNA damage and gastric tumorigenesis.
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- 2020
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40. Susceptibility-Guided Therapy vs. Bismuth-Containing Quadruple Therapy as the First-Line Treatment for Helicobacter pylori Infection: A Systematic Review and Meta-Analysis
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Yaobin Ouyang, Wenjing Zhang, Chen He, Yin Zhu, Nonghua Lu, and Yi Hu
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Helicobacter pylori ,susceptibility-guided therapy ,bismuth containing quadruple therapy ,efficacy ,meta-analysis ,Medicine (General) ,R5-920 - Abstract
BackgroundThe increased antibiotic resistance of Helicobacter pylori (H. pylori) has led to the decreased efficacy of H. pylori regimens.AimTo evaluate the efficacy, safety, and compliance of susceptibility-guided therapy (SGT) vs. bismuth-containing quadruple therapy (BQT) as the first-line treatment for H. pylori infection.Materials and MethodsThis meta-analysis was performed in accordance with the PRISMA 2009 guidelines. A systematic search in PubMed, Embase, and Cochrane databases was conducted using the combination of “H. pylori or H. pylori or Hp,” “bismuth quadruple,” and “tailored eradication OR tailored therapy OR susceptibility-guided therapy OR personalized therapy OR antibiotic susceptibility testing.”ResultsFive studies with 2,110 H. pylori-infected patients were enrolled. The pooled eradication rates of SGT and BQT were 86 vs. 78% (p < 0.05) and 92 vs. 86% (p > 0.05) by intention-to-treat (ITT) and per-protocol (PP) analyses, respectively. SGT has a significantly superior efficacy than BQT [pooled risk ratio (RR) = 1.14, p < 0.05] in a subgroup of cultures with the susceptibility test. The pooled side effect rate was 20% in SGT and 22% in BQT, which showed no significant difference (p > 0.05). The compliances of SGT and BQT were 95 and 92%, respectively.ConclusionCompared with BQT, SGT showed a higher efficacy and similar safety as the first-line treatment of H. pylori infection in areas with high antibiotic resistance. The decision-making of first-line regimens for H. pylori infection should depend on the availability and cost-effectiveness of susceptibility tests and bismuth in local areas.
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- 2022
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41. Global classical solutions to the 1-D vacuum free boundary problem for full compressible Navier-Stokes equations with large data.
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Yaobin Ou
- Subjects
- *
COMPRESSIBLE flow , *BOUNDARY value problems , *NAVIER-Stokes equations , *EXISTENCE theorems , *UNIQUENESS (Mathematics) - Abstract
The vacuum free boundary problem of one-dimensional non-isentropic compressible Navier-Stokes equations with large initial data is investigated in this paper. The fluid is initially assumed to occupy a finite interval and connect to the vacuum continuously at the free boundary, which is often considered in the gas-vacuum interface problem. Using the method of Lagrangian particle path, we derive some point-wise estimates and weighted spatial and time energy estimates for the classical solutions. Then the global existence and uniqueness of classical solutions are shown, and the expanding speed for the free boundary is proved to be finite. The main difficulty of this problem is the degeneracy of the system near the free boundary. Previous results are only for the solutions with low regularity (cf. [G. Q. Chen and M. Kratka, Commun. Partial Differ. Equations. 27 907-943 (2002)]). [ABSTRACT FROM AUTHOR]
- Published
- 2017
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42. The NF-κB Signaling Pathway, the Microbiota, and Gastrointestinal Tumorigenesis: Recent Advances
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Chao Peng, Yaobin Ouyang, Nonghua Lu, and Nianshuang Li
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NF-κB signaling pathway ,Helicobacter pylori ,microbiota ,gastric cancer ,colorectal cancer ,Immunologic diseases. Allergy ,RC581-607 - Abstract
Gastrointestinal (GI) cancers, especially gastric cancer and colorectal cancer (CRC), represent a major global health burden. A large population of microorganisms residing in the GI tract regulate physiological processes, such as the immune response, metabolic balance, and homeostasis. Accumulating evidence has revealed the alteration of microbial communities in GI tumorigenesis. Experimental studies in cell lines and animal models showed the functional roles and molecular mechanisms of several bacteria in GI cancers, including Helicobacter pylori in gastric cancer as well as Fusobacterium nucleatum, Escherichia coli, Peptostreptococcus anaerobius, and Bacteroides fragilis in CRC. The transcriptional factor NF-κB plays a crucial role in the host response to microbial infection through orchestrating innate and adaptive immune functions. Moreover, NF-κB activity is linked to GI cancer initiation and development through its induction of chronic inflammation, cellular transformation and proliferation. Here, we provide an overview and discussion of modulation of the NF-κB signaling pathway by microbiota, especially infectious bacteria, in GI tumorigenesis, with a major focus on gastric cancer and CRC.
- Published
- 2020
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43. Integrative Analysis of Differential lncRNA/mRNA Expression Profiling in Helicobacter pylori Infection-Associated Gastric Carcinogenesis
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Nianshuang Li, Yaobin Ouyang, Sihai Chen, Chao Peng, Cong He, Junbo Hong, Xiaoyu Yang, Yin Zhu, and Nong-Hua Lu
- Subjects
Helicobacter pylori ,RNA sequencing ,lncRNA ,mRNA ,gastric cancer ,Microbiology ,QR1-502 - Abstract
Helicobacter pylori (H. pylori) infection is the greatest known risk factor for gastric cancer (GC). Long non-coding RNAs (lncRNAs) are implicated in multiple biological processes. However, their contribution in H. pylori-associated GC remains largely unknown. We performed transcriptome sequencing to investigate differential lncRNA and mRNA expression profiles in gastric AGS cells infected with the H. pylori strain 7.13 or 43504. We identified significantly differentially expressed (SDE) mRNAs and lncRNAs following H. pylori infection. A co-expression network of lncRNAs and mRNAs was constructed via WGCNA analysis. Moreover, several of the most significantly upregulated genes were selected for further validation by qRT-PCR analysis in H. pylori-infected gastric cells and transgenic INS-GAS mice. We finally evaluated these genes in human GC tissues. A total of 158442 genes were identified between uninfected and infected cells. Of these, 298 mRNAs and 73 lncRNAs were consistently differentially expressed following infection with the H. pylori 7.13 and 43504 strains, respectively. The expression levels of most upregulated mRNAs (DDIT4, NDRG1, CHAC1, IL32, RELB, CTH, and SLC7A1) and lncRNAs (lncRNA36068, lncRNA51663, lncRNA49853, lncRNA49852, and FLJ46906) were validated by qRT-PCR analysis. We found that H. pylori infection significantly induced the transcript levels of the coding genes RELB and SLC7A11 in in vitro and in vivo assays, which was supported by their high expression levels in GC tissues. In addition, lncRNA51663 and FLJ46906 were remarkably increased in H. pylori-infected cells and consistently overexpressed in human GC tissues compared to adjacent normal tissues. Our study identified mRNA and lncRNA expression profiles related to H. pylori infection. These results may provide important insights regarding lncRNAs in H. pylori-induced gastric carcinogenesis.
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- 2020
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44. Helicobacter pylori CagA promotes epithelial mesenchymal transition in gastric carcinogenesis via triggering oncogenic YAP pathway
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Nianshuang Li, Yan Feng, Yi Hu, Cong He, Chuan Xie, Yaobin Ouyang, Stephen C. Artim, Deqiang Huang, Yin Zhu, Zhijun Luo, Zhongming Ge, and Nonghua Lu
- Subjects
H. pylori CagA ,YAP ,Epithelial-mesenchymal transition ,Gastric carcinogenesis ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Abstract Background Helicobacter pylori (H. pylori) delivers oncoprotein CagA into gastric epithelial cells via the T4SS and drives activation of multiple oncogenic signalling pathways. YAP, a core effector of the Hippo tumour suppressor pathway, is frequently overexpressed in human cancers, suggesting its potential tumor-promoting role. Although CagA is a casual factor in H. pylori induced gastric carcinogenesis, the link between CagA and YAP pathway has not been identified. In this work, we investigated the regulation of oncogenic YAP pathway by H. pylori CagA. Methods Expression of YAP and E-cadherin protein in human gastric biopsies were assessed by immunohistochemistry. H. pylori PMSS1 cagA − isogenic mutant strains were generated. Gastric epithelial cells were co-cultured with H. pylori wild-type cagA + strains or isogenic mutants and were also treated by recombinant CagA expression. Immunofluorescence was performed for YAP localization. Immunoblot and quantitative PCR were performed for examining levels of YAP, downstream effectors and markers of epithelial-mesenchymal transition. Verteporfin and siRNA silencing were used to inhibit YAP activity. Results YAP is significantly upregulated in human gastric carcinogenesis. We generated PMSS1 CagA isogenic mutant strains with chloramphenicol resistance successfully. Our analysis indicated that H. pylori infection induced YAP and downstream effectors in gastric epithelial cells. Importantly, knockout of CagA in 7.13 and PMSS1 strains reduced the expression of YAP by H. pylori infection. Moreover, Inhibition of YAP suppressed H. pylori infection-induced Epithelial-mesenchymal transition (EMT). Conclusion Our results indicated that H. pylori CagA as a pathogenic protein promotes oncogenic YAP pathway, which contributes to EMT and gastric tumorigenesis. This study provided a novel mechanistic insight into why cagA + H. pylori infection is associated with a higher risk for the development of gastric cancer.
- Published
- 2018
- Full Text
- View/download PDF
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