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convergent and divergent beam electron holography and reconstruction of adsorbates on free-standing two-dimensional crystals

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Frontiers of physics 2019年第1期14卷 43-57页

作者： T. Latychevskaia C. R. Woods Yi Bo Wang M. Holwill E. Prestat S. J. Haigh K. S. Novoselov Institute of Physics Laboratory for Ultrafast Microscopy and Electron Scattering (LUMES)école Polytechnique Fédérale de Lausanne (EPFL) CH-1015 Lausanne Switzerland National Graphene Institute University of Manchester Oxford Road Manchester M13 9PL UK School of Physics and Astronomy University of Manchester Oxford Road Manchester M13 9PL UK School of Materials University of Manchester Oxford Road Manchester M13 9PL UK

Van der Waals heterostructures have been lately intensively studied because they offer a large variety of properties that can be controlled by selecting 2D materials and their sequence in the stack. The exact arrangement of the layers as well as the exact arrangement of the atoms within the layers, both are important for the properties of the resulting device. However, it is very difficult to control and characterize the exact position of the atoms and the layers in such heterostructures, in particular, along the vertical (z) dimension. Recently it has been demonstrated that convergent beam electron diffraction (CBED) allows quantitative three-dimensional mapping of atomic positions in three-dimensional materials from a single CBED pattern. In this study we investigate CBED in more detail by simulating and performing various CBED regimes, with convergent and divergent wavefronts, on a somewhat simplified system: a two-dimensional (2D) monolayer crystal. In CBED, each CBED spot is in fact an in-line hologram of the sample, where in-line holography is known to exhibit high intensity contrast in detection of weak phase objects that are not detectable in conventional in-focus imaging mode. Adsorbates exhibit strong intensity contrast in the zero and higher order CBED spots, whereas lattice deformation such as strain or rippling cause noticeable intensity contrast only in the first and higher order CBED spots. The individual CBED spots can thus be reconstructed as typical in-line holograms, and a resolution of 2.13 A can in principle be achieved in the reconstructions. We provide simulated and experimental examples of CBED of a 2D monolayer crystal. The simulations show that individual CBED spots can be treated as in-line holograms and sample distributions such as adsorbates, can be reconstructed. Individual atoms can be reconstructed from a single CBED pattern provided the later exhibits high-order CBED spots. The experimental results were obtained in a transmission ele

关键词： graphene two-dimensional materials van der Waals structures electron holography convergent beam electron diffraction

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Comparative transcriptomics highlights convergent evolution of energy metabolic pathways in group-living spiders

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Zoological Research 2021年第2期42卷 195-206页

作者： Han Yang Bin Lyu Hai-Qiang Yin Shu-Qiang Li Key Laboratory of Zoological Systematics and Evolution Institute of ZoologyChinese Academy of SciencesBeijing 100101China Chengdu Institute of Biology Chinese Academy of SciencesChengduSichuan 610041China College of Life Science Hunan Normal UniversityChangshaHunan 410081China College of Life Sciences University of Chinese Academy of SciencesBeijing 100049China

Although widely thought to be aggressive, solitary,and potentially cannibalistic, some spider species have evolved group-living behaviors. The distinct transition provides the framework to uncover groupliving evolution. Here, we conducted a comparative transcriptomic study and examined patterns of molecular evolution in two independently evolved group-living spiders and twelve solitary species. We report that positively selected genes among groupliving spider lineages are significantly enriched in nutrient metabolism and autophagy pathways. We also show that nutrient-related genes of group-living spiders convergently experience amino acid substitutions and accelerated relative evolutionary rates. These results indicate adaptive convergence of nutrient metabolism that may ensure energy supply in group-living spiders. The decelerated evolutionary rate of autophagy-related genes in group-living lineages is consistent with an increased constraint on energy homeostasis as would be required in a group-living environment. Together, the results show that energy metabolic pathways play an important role in the transition to group-living in spiders.

关键词： Autophagy Cannibalism convergent Group-living Nutrient Spider

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Investigation of convergent Richtmyer–Meshkov instability at tin/xenon interface with pulsed magnetic driven imploding

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Chinese Physics B 2019年第4期28卷 247-253页

作者： Shaolong Zhang Wei Liu Guilin Wang Zhengwei Zhang Qizhi Sun Zhaohui Zhang Jun Li Yuan Chi Nanchuan Zhang Institute of Fluid Physics China Academy of Engineering Physics

The Richtmyer–Meshkov instability at the interface of solid state tin material and xenon gases under cylinder geometry is studied in this paper. The experiments were conducted at FP-1 facility in Institute of Fluid Physics, China Academy of Engineering Physics(CAEP). The FP-1 facility is a pulsed power driver which could generate high amplitude magnetic field to drive metal liner imploding. convergent shock wave was generated by impacting a magnetic-driven aluminium liner onto a inner mounted tin liner. The convergent evolution of the disturbance pre-machined onto the tin liner's inner surface was diagnosed by x-radiography. The spike amplitudes were derived from x-ray frames and were compared with linear *** analytical model containing material strength effect was derived and matched well to the experimental results. This sensibility of the disturbance evolution to material strength property shines light to the application of Richtmyer–Meshkov instability to infer material strength.

关键词： Richtmyer–Meshkov instability pulsed power driver convergent shock wave

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A Post-domestication Mutation, Dt2, Triggers Systemic Modification of Divergent and convergent Pathways Modulating Multiple Agronomic Traits in Soybean

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Molecular Plant 2019年第10期12卷 1366-1382页

作者： Dajian Zhang Xutong Wang Shuo Li Chaofan Wang Michael JGosney Michael VMickelbart Jianxin Ma Department of Agronomy Purdue UniversityWest LafayetteIN 47907USA College of Agronomy Shandong Agricultural UniversityTai'anShandong 271018China School of Life Sciences Shandong UniversityQingdaoShandong 266237China Department of Botany and Plant Pathology Purdue UniversityWest LafayetteIN 47907USA Center for Plant Biology Purdue UniversityWest LafayetteIN 47907USA

The semi-determinate stem growth habit in leguminous crops,similar to the“green revolution”semi-dwarf trait in cereals,is a key plant architecture trait that affects several other traits determining grain *** soybean semi-determinacy is modulated by a post-domestication gain-of-function mutation in the gene,Dt2,which encodes an MADS-box transcription ***,its role in systemic modification of stem growth and other traits is *** this study,we show that Dt2 functions not only as a direct repressor of Dt1,which prevents terminal flowering,but also as a direct activator of putative floral integrator/identity genes including GmSOC1,GmAP1,and GmFUL,which likely promote *** also demonstrate that Dt2 functions as a direct repressor of the putative drought-responsive transcription factor gene GmDREB1D,and as a direct activator of GmSPCH and GmGRP7,which are potentially associated with asymmetric division of young epidermal cells and stomatal opening,respectively,and may affect the plant's water-use efficiency(WUE).Intriguingly,Dt2 was found to be a direct activator or repressor of the precursors of eight microRNAs targeting genes potentially associated with meristem maintenance,flowering time,stomatal density,WUE,and/or stress *** study thus reveals the molecular basis of pleiotropy associated with plant productivity,adaptability,and environmental resilience.

关键词： abiotic stress agronomic traits convergent pathways stem growth habit pleiotropy soybean

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UNIFORMLY convergent NONCONFORMING TETRAHEDRAL ELEMENT FOR DARCY-STOKES PROBLEM

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Journal of Computational Mathematics 2019年第1期37卷 130-150页

作者： Lina Dong Shaochun Chen Department of Mathematics Henan Finance UniversityZhengzhou 450046China Department of Mathematics Zhengzhou UniversityZhengzhou 450001China

In this paper,we construct a tetrahedral element named DST20 for the three dimensional Darcy-Stokes problem,which reduces the degrees of velocity in [30].The finite element space Vh for velocity is H(div)-conforming,i.e.,the normal component of a function in Vh is continuous across the element boundaries,meanwhile the tangential component of a function in Vh is average continuous across the element boundaries,hence Vh is H^1- average *** prove that this element is uniformly convergent with respect to the perturbation constant s for the Darcy-Stokes *** the same time,we give a discrete de Rham complex corresponding to DST20 element.

关键词： Darcy-Stokes problem Mixed finite elements Tetrahedral element Uniformly convergent

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The provenance analysis of Late Triassic sedimentary sequences in Tethyan Himalaya: The tectonic attribute of materials at the convergent margin

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Science China Earth Sciences 2019年第10期62卷 1659-1661页

作者： Guangwei LI School of Earth Sciences The University of Melbourne

The Late Triassic is one of the key breakup periods of the eastern Gondwana margin and early-stage evolution of the Neo-Tethys,which traversed Laurasia and Gondwana at that time.A series of Late Triassic marine sedimentary sequences,preserved within the Himalaya(*** Himalaya)of southern Tibet,provides crucial and reliable information for understanding geological evolution processes.

关键词： The provenance analysis of Late Triassic sedimentary sequences in Tethyan Himalaya The tectonic attribute of materials at the convergent margin

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A Finite-Time convergent Analysis of Continuous Action Iterated Dilemma

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IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 563-565页

作者： Zhen Wang Xiaoyue Jin Tao Zhang Dengxiu Yu Northwestern Polytechnical University

Dear Editor,In this letter, a finite-time convergent analysis of continuous action iterated dilemma(CAID) is proposed. In traditional evolutionary game theory, the strategy of the player is binary(cooperation or defec... 详细信息

关键词： lemma letter convergent

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A New convergent Algorithm for Online Empirical Risk Minimization 36

A New Convergent Algorithm for Online Empirical Risk Minimiz...

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第36届中国控制会议

作者： Xinqiang Wang Lei Guo Key Lab.of Systems and Control Institute of Systems ScienceAMSSCAS

ISBN: (纸本)9781538629185

The generalization ability of learning algorithms is the focus of machine learning research,where the empirical risk minimization（ERM） plays an important role when the population distribution of observations is *** of the previous results are mainly based on computational learning theory,which is interested in how many samples are needed to make sure the estimated expected risk satisfies a given accuracy with high *** this paper,we will propose a new algorithm by combining the advantages of both random search and gradient descent algorithms,and show that given an accuracy level of the estimated expected risk,we can generate a hypothesis by our algorithm to guarantee the accuracy with probability 1,and our algorithm will converge in finite *** addition,we will relax the conventional independently and identically distributed（i.i.d.）assumption on the observations to a kind of weakly dependent *** will also provide some simulations to demonstrate our algorithm’s advantages over either random search or gradient descent algorithms.

关键词： ERM random search convergent gradient descent machine learning

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Global lessons on delivery of primary healthcare services for people with non-communicable diseases:convergent mixed methods

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Family Medicine and Community Health 2024年第3期12卷 13-24页

作者： Robert Mash Lisa R Hirschhorn Inayat Singh Kakar Renu John Manushi Sharma Devarsetty Praveen Stellenbosch University StellenboschSouth Africa Northwestern University ChicagoIllinoisUSA The George Institute for Global Health New DelhiIndia The George Institute for Global Health HyderabadIndia Manipal Academy of Higher Education ManipalIndia

Objective To extract key lessons on primary healthcare(PHC)service delivery strategies for non-communicable diseases(NCD)from the work of researchers funded by the Global Alliance for Chronic Diseases(GACD).Design A convergent mixed methods study that extracted data using a standardised template from research projects funded by the GACD that focused on *** strategies implemented in these studies were mapped onto the PHC Performance Initiative *** qualitative interviews were conducted with researchers from purposefully selected projects to understand the strategies and contextual factors in more *** PHC contexts from low or middle-income countries(LMIC)as well as vulnerable groups within high-income *** came from all regions of the world,particularly East Asia and Pacific,sub-Saharan Africa,South Asia,Latin America and *** The study extracted data on 84 research projects and interviewed researchers from 16 research *** Research projects came from all regions of the world,and mainly focused on diabetes(35.3%),hypertension(28.3%)and mental health(27.6%).Mapped onto the PHC Performance Initiative framework:49.4%focused on high-quality PHC(particularly the comprehensiveness of NCD care,41.2%);41.2%on the availability of PHC services(particularly the competence of healthcare workers,36.5%);35.3%on population health management(particularly community-based services,35.3%);34.1%on facility organisation and management(particularly team-based care,20.0%)and 31.8%on access(particularly digital technology,23.5%).Most common strategies were task shifting and training to improve the comprehensiveness of NCD care through community-based *** factors related to inputs:infrastructure,equipment and medication,workforce(particularly community health workers),finances,health information systems and digital *** Key strategies and contextual factors to improve PHC service del

关键词： services convergent income

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UNIFORMLY HIGHER ORDER ACCURATE EXTRAPOLATIONS TO SOLUTIONS OF UNIFORMLY convergent DISCRETIZATION METHODS FOR SINGULARLY PERTURBED PROBLEMS

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Applied Mathematics and Mechanics(English Edition) 1990年第3期11卷 271-276页

作者：孙光甫 Department of Computer Science Fuzhou University Fuzhou

We discuss the uniformly higher order accurate extrapolations, which are based on the uniform expansion for global error, to solutions of uniformly convergent discretization methods for singularly perturbed problems. By applying the approach to the in-Allen-Southwell scheme for a non-self-adjoint problem, we obtain an extrapolation solution which is uniformly convergent with order two. We confirm the result by numerical calculations.

关键词： convergent uniformly applying perturbed Richardson satisfy adjoint singularly perturbation Uniform

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