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Vision Transformers with Hierarchical Attention

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Machine Intelligence Research 2024年第4期21卷 670-683页

作者： yun Liu Yu-Huan Wu Guolei sun Le Zhang Ajad Chhatkuli Luc Van Gool Institute for Infocomm Research(I2R) A*STARSingapore 138632Singapore Institute of High Performance Computing(IHPC) A*STARSingapore 138632Singapore Computer Vision Lab ETH ZürichZürich 8092Switzerland School of Information and Communication Engineering University of Electronic Science and Technology of China(UESTC)Chengdu 611731China

This paper tackles the high computational/space complexity associated with multi-head self-attention(MHSA)in vanilla vision *** this end,we propose hierarchical MHSA(H-MHSA),a novel approach that computes self-attention in a hierarchical ***,we first divide the input image into patches as commonly done,and each patch is viewed as a ***,the proposed H-MHSA learns token relationships within local patches,serving as local relationship ***,the small patches are merged into larger ones,and H-MHSA models the global dependencies for the small number of the merged *** last,the local and global attentive features are aggregated to obtain features with powerful representation *** we only calculate attention for a limited number of tokens at each step,the computational load is reduced ***,H-MHSA can efficiently model global relationships among tokens without sacrificing fine-grained *** the H-MHSA module incorporated,we build a family of hierarchical-attention-based transformer networks,namely *** demonstrate the superiority of HAT-Net in scene understanding,we conduct extensive experiments on fundamental vision tasks,including image classification,semantic segmentation,object detection and instance ***,HAT-Net provides a new perspective for vision *** and pretrained models are available at https://***/yun-liu/HAT-Net.

关键词： Vision transformer hierarchical attention global attention local attention scene understanding.

Systematic bibliometric analysis of research hotspots and trends on the application of premium IOLs in the past 2 decades

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International Journal of Ophthalmology(English edition) 2024年第4期17卷 736-747页

作者： Liang-Pin Li Li-yun Yuan De-Shen Mao xia Hua xiao-Yong Yuan Clinical College of Ophthalmology Tianjin Medical UniversityTianjin 300020China Tianjin Key Laboratory of Ophthalmology and Visual Science Tianjin Eye InstituteTianjin Eye HospitalTianjin 300020China School of Medicine Nankai UniversityTianjin 300071China Anhui Medical University Hefei 230032Anhui ProvinceChina Tianjin Aier Eye Hospital Tianjin UniversityTianjin 300190China

AIM:To analysis of research hotspots and trends on the application of premium intraocular lens(PIOLs)in the past 2 ***:The literature search was performed on the Web of Science and included PIOLs studies published between January 2000 and December *** retrieved literature was collated and analyzed by R-tool’s Bibliometrix package,CitNetExplorer,CiteSpace and other ***:A total of 1801 articles about PIOLs were obtained,most of which were published in Spain and the United *** organization that published the most articles was the University of Valencia in ***ó JL,and Montés-Micó R,from Spain were the most influential authors in this *** Journal of Cataract and Refractive Surgery and Journal of Refractive Surgery were the core journals for this field;the top 10 cited articles mainly focus on postoperative satisfaction with multifocal intraocular lens(IOLs)and postoperative results of toric *** the keyword analysis,we found that trifocal IOLs,astigmatism and extended depth of focus(EDoF)IOLs are the most discussed topics at present,and the importance of astigmatism and the clinical application of the new generation of PIOLs are the emerging research ***:Bibliometric analysis can effectively help to identify multilevel concerns in PIOLs research and the prevailing research trends in the realm of PIOLs encompass the adoption of EDoF IOLs,trifocal IOLs,and their respective Toric models.

关键词： premium intraocular lens bibliometric H-index cataract surgery global trends

Channel erosion and its impact on environmental flow of riparian habitat in the Middle Yangtze River

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Environmental Science and Ecotechnology 2024年第4期20卷 229-236页

作者： Shanshan Deng Junqiang xia Heng Zhu Jie Liang Huiwen sun Xin Liu State Key Laboratory of Water Resources Engineering and Management Wuhan UniversityWuhan430072China College of Environmental Science and Engineering Hunan UniversityKey Laboratory of Environmental Biology and Pollution Control(Hunan University)Ministry of EducationChangsha410082China

Evaluating environmental flow(EF)is pivotal for conserving and restoring riverine ***,prevalent EF evaluations presume that a river reach's hydraulic conditions are exclusively governed by inflow discharge,presupposing a state of equilibrium in the river *** presumption narrows the scope of EF evaluations in expansive alluvial rivers like the Middle Yangtze River(MYR),characterized by marked channel *** we show the profound channel erosion process and its impact on EF requirements for riparian habitats within the *** research unveils that:(i)pronounced erosion has led to a mean reduction of 1.0-2.7 m in the riverbed across four sub-reaches of the MYR;(ii)notwithstanding a 37-107%increase in minimal discharges post the Three Gorges Project,the lowest river stages at some hydrometric stations diminished owing to bed erosion,signifying a notable transformation in MYR's hydraulic dynamics;(iii)a discernible rightward shift in the correlation curve between the weighted useable area and discharge from 2002 to 2020 in a specific sub-reach of the MYR,instigated by alterations in hydraulic conditions,necessitated an increase of 1500e2600 m^(3)s^(-1)in the required EF for the sub-reach;(iv)it is deduced that macroinvertebrate biomass rapidly decreases as the flow entrains the riverbed substrate,with the maximum survivable velocity for macroinvertebrates being contingent on their entrainment *** findings highlight the importance of incorporating channel morphological changes in devising conservation strategies for the MYR ecosystem.

关键词： Increased environmental flow requirement River bed level lowering Hydraulic condition change Middle Yangtze River

The Boundedness of the Pullback Attractor for a 2D Micropolar Fluid Flows

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Acta Mathematicae Applicatae Sinica 2024年

作者： Wen-long sun Chun-lin LAI yun-yun LIANG School of information and mathematics Yangtze University

The purpose of this work is to investigate the boundedness of the pullback attractors for the micropolar fluid flows in two-dimensional unbounded domains. Exactly, the H1-boundedness and H2-boundedness of the pullback attractors are established when the external force F (t, x) has different regularity with respect to time variable, respectively.

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Understanding the cooperative effects in the catalysis of homodimeric fluoroacetate dehalogenase

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Science China Chemistry 2024年第7期67卷 2382-2391页

作者： Ke-Wei Chen Jia-Nan Chen Jun Zhang Chao Wang Tian-Yu sun yun-Dong Wu Key Laboratory of Computational Chemistry and Drug Design State Key Laboratory of Chemical OncogenomicSchool of Chemical Biology and BiotechnologyPeking University Shenzhen Graduate SchoolShenzhen 518055China Institute of Chemical Biology Shenzhen Bay LaboratoryShenzhen 518132China College of Chemistry and Molecular Engineering Peking UniversityBeijing 100871China Changping Laboratory Beijing 102200China

Fluoroacetate dehalogenases(FAcD),a homodimeric enzyme,catalyzes the conversion of fluoroacetic acid to glycolic acid(GoA).It has been proved that the enzyme has a half-of-the-site ***,its catalytic(C)subunit converts the first substrate to a covalent intermediate;then,the non-catalytic(NC)subunit binds a second substrate and promotes the conversion of the intermediate in the C subunit into the final *** the release of the product,the C subunit becomes the NC subunit,and the previous NC subunit becomes the C *** elucidate the detailed mechanism behind this cooperative catalysis,we have conducted microsecond-scale MD simulations along the reaction *** simulations indicate that the substrate in the NC subunit induces W185 and Y141 adopting an open conformation in the C *** opening of W185(C)facilitates the entry of catalytic water,enhancing the catalytic activity for product formation,while the opening of Y141(C)creates an unfavorable environment for product binding,promoting its *** interaction network analysis reveals that the substrate in the NC subunit can induce conformational changes through a conserved water chain at the interface.

关键词： enzyme catalysis molecular dynamics cooperative effect pre-reaction state

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Rational Design and Construction of a CdS QDs/InVO4 Atomic-Layer（110）/（110） Facet S-Scheme Heterojunction for Highly Efficient Photocatalytic Degradation of C2H4

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Energy & Environmental Materials 2024年第3期7卷 215-222页

作者： Yuanpeng Dong Peizhu Ji Xinyue Xu Rong Li Yin Wang Kevin Peter Homewood xiaohong xia yun Gao Xuxing Chen Ministry of Education Key Laboratory for the Green Preparation and Application of Functional Materials School of Materials Science&Engineering Hubei University Hubei Key Laboratory of Low Dimensional Optoelectronic Materials and Devices Hubei University of Arts and Science State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of Matter Chinese Academy of Sciences United Water (xianning) Company Limited

Exploring high efficiency S-scheme heterojunction photocatalysts with strong redox ability for removing volatile organic compounds from the air is of great interest and ***,how to predict and regulate the transport of photogenerated carriers in heterojunctions is a great ***,density functional theory calculations were first used to successfully predict the formation of a CdS quantum dots/InVO4atomic-layer （110）/（110） facet S-scheme ***,a CdS quantum dots/InVO4atomic-layer was synthesized by in-situ loading of CdS quantum dots with （110） facets onto the（110） facets of *** a result of the deliberately constructed built-in electric field between the adjoining facets,we obtain a remarkably enhanced photocatalytic degradation rate for *** rate is 13.8 times that of pure CdS and 13.2 times that of pure ***-situ irradiated X-ray photoelectron spectroscopy,photoluminescence and time-resolved photoluminescence measurements were carried *** experiments validate that the built-in electric field enhanced the dissociation of photoexcited excitons and the separation of free charge carriers,and results in the formation of S-scheme charge transfer *** reaction mechanism of the photocatalytic C2H4oxidation is investigated by in-situ electron paramagnetic *** work provides a mechanistic insight into the construction and optimization of semiconductor heterojunction photocatalysts for application to environmental remediation.

关键词： CdS QDs InVO4 atomic-layer photocatalysis S-scheme volatile organic compounds

Enlarged DNA unwinding by Nme2Cas9 permits a broadened base editing window beyond the protospacer

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Science China(Life Sciences) 2024年第2期67卷 424-427页

作者： Ziting Chen xiangyang Li Qian Zhang Wenjun sun xiaoxuan Song xia Zhang Xingxu Huang Bo sun School of Life Science and Technology and Gene Editing Center ShanghaiTech UniversityShanghai 201210China Zhejiang Lab HangzhouZhejiang 311121China CAS Center for Excellence in Molecular Cell Science Shanghai Institute of Biochemistry and Cell BiologyChinese Academy of SciencesShanghai 200031China University of Chinese Academy of Sciences Beijing 100049China

Dear Editor,Base editing has been developed to be one of the effective CRISPR-based gene editing techniques(Rees and Liu,2018).Base editors(BEs)take advantage of DNAmodifying enzymes fused with a catalytically impaired CRISPR protein to install base *** BE,DNA-modifying enzymes often process nontarget singlestranded DNA(NTS)generated by Cas proteins.

关键词： install base winding

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High-resolution neutronics model for ^(238)Pu production in high-flux reactors

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Nuclear Science and Techniques 2024年第5期35卷 226-236页

作者： Qing-Quan Pan Qing-Fei Zhao Lian-Jie Wang Bang-Yang xia yun Cai Jin-Biao Xiong xiao-Jing Liu School of Nuclear Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610200China

We proposed and compared three methods(filter burnup,single energy burnup,and burnup extremum analysis)to build a high-resolution neutronics model for 238Pu production in high-flux *** filter burnup and single energy burnup methods have no theoretical approximation and can achieve a spectrum resolution of up to~1 eV,thereby constructing the importance curve and yield curve of the full energy *** burnup extreme analysis method combines the importance and yield curves to consider the influence of irradiation time on production efficiency,thereby constructing extreme *** three curves,which quantify the transmutation rate of the nuclei in each energy region,are of physical significance because they have similar distributions.A high-resolution neutronics model for ^(238)Pu production was established based on these three curves,and its universality and feasibility were *** neutronics model can guide the neutron spectrum optimization and improve the yield of ^(238)Pu by up to 18.81%.The neutronics model revealed the law of nuclei transmutation in all energy regions with high spectrum resolution,thus providing theoretical support for high-flux reactor design and irradiation production of ^(238)Pu.

关键词： ^(238)Pu Neutronics model High-flux reactor Spectrum resolution Spectrum optimization

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Modeling Reynolds stress anisotropy invariants via machine learning

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Acta Mechanica Sinica 2024年第6期40卷 50-63页

作者： xianglin Shan Xuxiang sun Wenbo Cao Weiwei Zhang Zhenhua xia School of Aeronautics Northwestern Polytechnical UniversityXi’an710072China Department of Engineering Mechanics Zhejiang UniversityHangzhou310027China

The presentation and modeling of turbulence anisotropy are crucial for studying large-scale turbulence structures and constructing turbulence ***,accurately capturing anisotropic Reynolds stresses often relies on expensive direct numerical simulations(DNS).Recently,a hot topic in data-driven turbulence modeling is how to acquire accurate Reynolds stresses by the Reynolds-averaged Navier-Stokes(RANS)simulation and a limited amount of data from *** existing studies use mean flow characteristics as the input features of machine learning models to predict high-fidelity Reynolds stresses,but these approaches still lack robust generalization *** this paper,a deep neural network(DNN)is employed to build a model,mapping from tensor invariants of RANS mean flow features to the anisotropy invariants of high-fidelity Reynolds *** the aspects of tensor analysis and input-output feature design,we try to enhance the generalization of the model while preserving invariance.A functional framework of Reynolds stress anisotropy invariants is derived *** irreducible invariants are then constructed from a tensor group,serving as alternative input features for ***,we propose a feature selection method based on the Fourier transform of periodic *** results demonstrate that the data-driven model achieves a high level of accuracy in predicting turbulence anisotropy of flows over periodic hills and converging-diverging ***,the well-trained model exhibits strong generalization capabilities concerning various shapes and higher Reynolds *** approach can also provide valuable insights for feature selection and data generation for data-driven turbulence models.

关键词： Reynolds stress Anisotropy invariant Tensor analysis Machine learning