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Intrinsic 1T̕ phase induced in atomically thin 2H-MoTe2 by a single terahertz pulse

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arXiv 2019年

作者： Shi, Jiaojian Bie, Ya-Qing Zong, Alfred Fang, Shiang Chen, Wei Han, Jinchi Cao, Zhaolong Zhang, Yong Taniguchi, Takashi Watanabe, Kenji Bulović, Vladimir Kaxiras, Efthimios Baldini, Edoardo Jarillo-Herrero, Pablo Nelson, Keith A. Department of Chemistry Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States State Key Lab of Optoelectronic Materials and Technologies Guangdong Province Key Laboratory of Display Material and Technology School of Electronics and Information Technology Sun Yat-sen University Guangzhou510275 China Department of Chemistry University of California BerkeleyCA94720 United States Department of Physics Harvard University CambridgeMA02138 United States Department of Physics and Astronomy Center for Materials Theory Rutgers University PiscatawayNJ08854 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Center for Materials Science & Engineering Massachusetts Institute of Technology CambridgeMA02139 United States International Center for Materials Nanoarchitectonics National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Research Center for Functional Materials National Institute for Materials Science 1-1 Namiki Tsukuba305-0044 Japan Department of Physics Center for Complex Quantum System The University of Texas at Austin AustinTX78712 United States

Polymorphic transitions in layered transition metal dichalcogenides provide an excellent platform for discovering exotic phenomena associated with metastable states, ranging from topological phase transitions1 to enhanced superconductivity2. In particular, the transition from 2H to 1T0-MoTe2, which was thought to be induced by high-energy photon irradiation3–5 among many other means6–9, has been intensely studied for its technological relevance in nanoscale transistors3. Despite the remarkable electrical performance arising from this 2H-to-1T0 transition, it remains controversial whether a crystalline 1T0 phase is produced because optical signatures of this putative transition are found to be associated with the formation of elemental Te clusters instead10,11. Here, we demonstrate the creation of an intrinsic 1T0 lattice after irradiating a mono- or few-layer 2H-MoTe2 with a single field-enhanced terahertz pulse, whose low photon energy limits possible structural damage by optical pulses. To visualize the temporal evolution of this irreversible transition, we further develop a single-shot terahertz pump-second harmonic probe technique, and we find that the transition out of the 2H phase occurs within 10 ns after photoexcitation. Our results not only resolve the long-standing debate over the light-induced polymorphic transition in MoTe2, they also highlight the unique capability of strong-field terahertz pulses in manipulating the structure of quantum materials. Copyright © 2019, The Authors. All rights reserved.

关键词： Transition metals

A Novel Environment Perception Algorithm Combining Biologically Inspired Features and Brain-like Memory Pattern

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Journal of Physics: Conference Series 2019年第2期1302卷

作者： Xingwei Yan Afeng Yang Chun Du Zhangmeng Liu State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System National University of Defense Technology No.109 Deya Road Kaifu District Changsha China College of Electronic Science National University of Defense Technology No.109 Deya Road Kaifu District Changsha China

In this paper, we proposed a novel framework for environment perception. The proposed model combines the physio-logical mechanisms of human vision and psychological principle of cognitive development. Our algorithm consists of two major components, a gist module and a memory module. The gist module simulates the cognition process associated with visual attention. The memory module is simulated by the Incremental Hierarchical Discriminant Regression (IHDR) tree, which ensures the memories of the world are distributed over the hierarchy. Experimental results on the USC dataset demonstrated that the proposed algorithm is robust and efficient.

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From first- to second-order phase transitions in hybrid improper ferroelectrics through entropy stabilisation

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arXiv 2020年

作者： Pomiro, Fernando Ablitt, Chris Bristowe, Nicholas C. Mostofi, Arash A. Won, Coongjae Cheong, Sang-Wook Senn, Mark S. Department of Chemistry University of Warwick Gibbet Hill CoventryCV4 7AL United Kingdom School of Physical Sciences University of Kent CanterburyCT2 7NH United Kingdom Departments of Materials and Physics Thomas Young Centre for Theory and Simulation of Materials Imperial College London Exhibition Road LondonSW7 2AZ United Kingdom Laboratory for Pohang Emergent Materials Max Plank POSTECH Center for Complex Phase Materials Pohang University of Science and Technology Pohang Korea Republic of Rutgers Center for Emergent Materials Department of Physics and Astronomy Rutgers University PiscatawayNJ United States

Hybrid improper ferroelectrics (HIFs) have been intensely studied over the last few years to gain understanding of their temperature induced phase transitions and ferroelectric switching pathways. Here we report a switching from first- to second-order phase transition pathway for topical HIFs Ca3−xSrxTi2O7, which is driven by the differing entropies of the phases that we identify as being associated with the dynamic motion of octahedral tilts and rotations. A greater understanding of the transition pathways in this class of layered perovskites, which host many physical properties that are coupled to specific symmetries and octahedral rotation and tilt distortions -such as superconductivity, negative thermal expansion, fast ion conductivity, ferroelectricity, among others- is a crucial step in creating novel functional materials by design. Copyright © 2020, The Authors. All rights reserved.

关键词： Thermal expansion

DOUBLE PHASE OBSTACLE PROBLEMS WITH MULTIVALUED CONVECTION AND MIXED BOUNDARY VALUE CONDITIONS

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arXiv 2021年

作者： Zeng, Shengda Radulescu, Vicent Iu D. Winkert, Patrick Guangxi Colleges Universities Key Laboratory of Complex System Optimization and Big Data Processing Yulin Normal University Guangxi Yulin537000 China Department of Mathematics Nanjing University Jiangsu Nanjing210093 China Jagiellonian University in Krakow Faculty of Mathematics and Computer Science ul. Lojasiewicza 6 Krakow30-348 Poland Faculty of Applied Mathematics AGH University of Science and Technology Kraków30-059 Poland Department of Mathematics University of Craiova Craiova200585 Romania China-Romania Research Center in Applied Mathematics Craiova Romania Technische Universität Berlin Institut für Mathematik Straße des 17. Juni 136 Berlin10623 Germany

In this paper, we consider a mixed boundary value problem with a double phase partial differential operator, an obstacle effect and a multivalued reaction convection term. Under very general assumptions, an existence theorem for the mixed boundary value problem under consideration is proved by using a surjectivity theorem for multivalued pseudomonotone operators together with the approximation method of Moreau-Yosida. Then, we introduce a family of the approximating problems without constraints corresponding to the mixed boundary value problem. Denoting by S the solution set of the mixed boundary value problem and by Sn the solution sets of the approximating problems, we establish the following convergence relation ∅ =6 w- lim sup Sn = s- lim sup Sn ⊂ S, n→∞ n→∞ where w-lim supn→∞ Sn and s-lim supn→∞ Sn stand for the weak and the strong Kuratowski upper limit of Sn, respectively. Copyright © 2021, The Authors. All rights reserved.

关键词： Mathematical operators

Spike-burst chimera states in an adaptive exponential integrate-and-fire neuronal network

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arXiv 2019年

作者： Santos, Moises S. Protachevicz, Paulo R. Iarosz, Kelly C. Caldas, Iberê L. Viana, Ricardo L. Borges, Fernando S. Ren, Hai-Peng Szezech, José D. Batista, Antonio M. Grebogi, Celso Department of Physics Federal University of Paraná CuritibaPR80060-000 Brazil Graduate in Science Program - Physics State University of Ponta Grossa Ponta Grossa PR84030-900 Brazil Institute of Physics University of São Paulo São PauloSP05508-900 Brazil Center for Mathematics Computation and Cognition Federal University of ABC São Bernardo do CampoSP09606-045 Brazil Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing Xian University of Technology Xi'an710048 China Xian Technological University Xi'an710021 China Graduate in Science Program - Physics State University of Ponta Grossa Ponta Grossa PR84030-900 Brazil Institute for Complex Systems and Mathematical Biology King's College University of Aberdeen AberdeenAB24 3UE United Kingdom

Chimera states are spatiotemporal patterns in which coherence and incoherence coexist. We observe the coexistence of synchronous (coherent) and desynchronous (incoherent) domains in a neuronal network. The network is composed of coupled adaptive exponential integrate-and-fire neurons that are connected by means of chemical synapses. In our neuronal network, the chimera states exhibit spatial structures both with spikes and bursts activities. Furthermore, those desynchronised domains not only have either spike or burst activity, but we show that the structures switch between spikes and bursts as the time evolves. Moreover, we verify the existence of multicluster chimera states. Copyright © 2019, The Authors. All rights reserved.

关键词： Neural networks

Hybrid Films: Kirigami-Inspired Deformable 3D Structures Conformable to Curved Biological Surface (Adv. Sci. 12/2018)

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Advanced science 2018年第12期5卷 1870073-1870073页

作者： Chao Yang Heng Zhang Youdi Liu Zhongliang Yu Xiaoding Wei Youfan Hu Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics Peking University Beijing 100871 P. R. China State Key Laboratory for Turbulence and Complex System Department of Mechanics and Engineering Science College of Engineering Peking University Beijing 100871 China Beijing Innovation Center for Engineering Science and Advanced Technology Peking University Beijing 100871 China

Effects of nonlinear gradient index on radiative heat transfer in a one-dimensional medium by the DRESOR method

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Journal of Physics: Conference Series 2012年第1期369卷

作者： Z C Wang Q Cheng G H Wang Z F Huang H C Zhou State Key Laboratory of Coal Combustion Huazhong University of Science and Technology Wuhan 430074 Hubei People's Republic of China State Key Laboratory of Control & Simulation of Power System & Generation Equipment Department of Thermal Engineering Tsinghua University Beijing 10084 P. R. China To whom any correspondence should be addressed

The DRESOR (Distribution of Ratios of Energy Scattered by the medium Or Reflected by the boundary surface) method is applied for radiative heat transfer in a one-dimensional medium with a nonlinear gradient index and gray boundary surfaces. In this proposed method, the DRESOR values calculated by the Monte Carlo method express quantitatively the impact of scattering on radiative transfer and the radiative intensity with high directional resolution of high precision can be easily obtained. With given media characteristics and boundary conditions, the temperature and radiative flux distributions inside the medium are calculated under the condition of radiative equilibrium. It is shown, in the cases studied, that the DRESOR method has a good accuracy. The temperature distributions have a node with different kinds of sine changed gradient index distributions under the same boundary emissivity. The impact of the gradient index on the radiative heat transfer is considerable, and the same as that of the ratios of its amplitude and average index. Besides, the effects of optical thickness, boundary emissivity and scattering phase function on radiative transfer also should be paid adequate attention.

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Characteristic Analysis of Monobit Signal

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Journal of Physics: Conference Series 2021年第1期1738卷

作者： Pengfei Ji Xiao Yang Chenglong Xia Huan Lv State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System Technology National University of Defense Technology Changsha Hunan 410073 China. School of Electronic Science National University of Defense Technology Changsha Hunan 410073 China. Military Representative Office of Rocket Force in Changsha Changsha Hunan 4100205 China.

This paper analyzes the characters of monobit signals and gives the reason why the spurious free dynamic ranges (SFDR) of monobit signals is much lower than those of multi-bit signals. According to our analysis and simulation, if the third harmonic of a monobit signal can be filtered, the SFDR of it can be improved well. Therefore, we give the way to obtain the desired band, which do not contain any third harmonics, and the simulation results are in agreement with our design. Such way can be used to improve the performance of monobit digital receivers in engineering.

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25th Annual Computational Neuroscience Meeting CNS-2016, Seogwipo City, South Korea, July 2-7, 2016 Abstracts

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BMC NEUROscience 2016年第1期17卷 1-112页

作者： [Anonymous] Computational Neurobiology Laboratory The Salk Institute for Biological Studies San Diego USA UNIC CNRS Gif sur Yvette France The European Institute for Theoretical Neuroscience (EITN) Paris France ATR Computational Neuroscience Laboratories Kyoto Japan Krembil Research Institute University Health Network Toronto Canada Department of Physiology University of Toronto Toronto Canada Department of Medicine (Neurology) University of Toronto Toronto Canada Department of Physics University of New Hampshire Durham USA Department of Neurophysiology Nencki Institute of Experimental Biology Warsaw Poland Department of Theory Wigner Research Centre for Physics of the Hungarian Academy of Sciences Budapest Hungary Department of Mathematical Sciences KAIST Daejoen Republic of Korea Department of Mathematics University of Houston Houston USA Department of Biochemistry & Cell Biology and Institute of Biosciences and Bioengineering Rice University Houston USA Department of Biology and Biochemistry University of Houston Houston USA Grupo de Neurocomputación Biológica Dpto. de Ingeniería Informática Escuela Politécnica Superior Universidad Autónoma de Madrid Madrid Spain Department of Biological Sciences University of Southern California Los Angeles USA Center for Neuroscience Korea Institute of Science and Technology Seoul South Korea Department of Neurology Albert Einstein College of Medicine Bronx USA Center for Neuroscience KIST Seoul South Korea Department of Neuroscience University of Science and Technology Daejon South Korea Systems Neuroscience Group QIMR Berghofer Medical Research Institute Herston Australia Department of Psychology Yonsei University Seoul South Korea Department of Psychiatry Kyung Hee University Hospital at Gangdong Seoul South Korea Department of Psychiatry Veterans Administration Boston Healthcare System and Harvard Medical School Brockton USA Department of Electrical and Electronic Engineering The University of Melbourne Parkvil

A1 Functional advantages of cell-type heterogeneity in neural circuits Tatyana O. Sharpee A2 Mesoscopic modeling of propagating waves in visual cortex Alain Destexhe A3 Dynamics and biomarkers of mental disorders Mitsuo Kawato F1 Precise recruitment of spiking output at theta frequencies requires dendritic h-channels in multi-compartment models of oriens-lacunosum/moleculare hippocampal interneurons Vladislav Sekulić, Frances K. Skinner F2 Kernel methods in reconstruction of current sources from extracellular potentials for single cells and the whole brains Daniel K. Wójcik, Chaitanya Chintaluri, Dorottya Cserpán, Zoltán Somogyvári F3 The synchronized periods depend on intracellular transcriptional repression mechanisms in circadian clocks. Jae Kyoung Kim, Zachary P. Kilpatrick, Matthew R. Bennett, Kresimir Josić O1 Assessing irregularity and coordination of spiking-bursting rhythms in central pattern generators Irene Elices, David Arroyo, Rafael Levi, Francisco B. Rodriguez, Pablo Varona O2 Regulation of top-down processing by cortically-projecting parvalbumin positive neurons in basal forebrain Eunjin Hwang, Bowon Kim, Hio-Been Han, Tae Kim, James T. McKenna, Ritchie E. Brown, Robert W. McCarley, Jee Hyun Choi O3 Modeling auditory stream segregation, build-up and bistability James Rankin, Pamela Osborn Popp, John Rinzel O4 Strong competition between tonotopic neural ensembles explains pitch-related dynamics of auditory cortex evoked fields Alejandro Tabas, André Rupp, Emili Balaguer-Ballester O5 A simple model of retinal response to multi-electrode stimulation Matias I. Maturana, David B. Grayden, Shaun L. Cloherty, Tatiana Kameneva, Michael R. Ibbotson, Hamish Meffin O6 Noise correlations in V4 area correlate with behavioral performance in visual discrimination task Veronika Koren, Timm Lochmann, Valentin Dragoi, Klaus Obermayer O7 Input-location dependent gain modulation in cerebellar nucleus neurons Maria Psarrou, Maria Schilstra, Neil Davey, Benjamin Torben-Ni

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