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arXiv 2019年

作者： Duong, Nghiep Khoan Raju, M. Petrović, A.P. Tomasello, R. Finocchio, G. Panagopoulos, Christos Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore637371 Institute of Applied and Computational Mathematics FORTH Heraklion-CreteGR-70013 Greece Department of Mathematical and Computer Sciences Physical Sciences and Earth Sciences University of Messina Messina98166 Italy

We present a study of the stability of room-temperature skyrmions in [Ir/Fe/Co/Pt] thin film multilayers, using the First Order Reversal Curve (FORC) technique and magnetic force microscopy (MFM). FORC diagrams reveal irreversible changes in magnetization upon field reversals, which can be correlated with the evolution of local magnetic textures probed by MFM. Using this approach, we have identified two different mechanisms - (1) skyrmion merger and (2) skyrmion nucleation followed by stripe propagation - which facilitate magnetization reversal in a changing magnetic field. Analysing the signatures of these mechanisms in the FORC diagram allows us to identify magnetic "histories" - i.e. precursor field sweep protocols - capable of enhancing the final zero-field skyrmion density. Our results indicate that FORC measurements can play a useful role in characterizing spin topology in thin film multilayers, and are particularly suitable for identifying samples in which skyrmion populations can be stabilized at zero field. Copyright © 2019, The Authors. All rights reserved.

关键词： Textures

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Inverting the markovian projection, with an application to local stochastic volatility models

arXiv

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arXiv 2019年

作者： Lacker, Daniel Shkolnikov, Mykhaylo Zhang, Jiacheng Ieor Department Columbia University New YorkNY10027 United States Orfe Department Bendheim Center for Finance Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 Orfe Department Princeton University PrincetonNJ08544 United States

We study two-dimensional stochastic differential equations (SDEs) of McKean- Vlasov type in which the conditional distribution of the second component of the solution given the first enters the equation for the first component of the solution. Such SDEs arise when one tries to invert the Markovian projection developed in [Gyö86], typically to produce an It o process with the fixed-time marginal distributions of a given one-dimensional diffusion but richer dynamical features. We prove the strong existence of stationary solutions for these SDEs, as well as their strong uniqueness in an important special case. Variants of the SDEs discussed in this paper enjoy frequent application in the calibration of local stochastic volatility models in finance, despite the very limited theoretical understanding. Copyright © 2019, The Authors. All rights reserved.

关键词： Stochastic systems

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computational Identification and Experimental Demonstration of High-Performance Methane Sorbents

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Angewandte Chemie 2022年第25期134卷

作者： Dr. Karabi Nath Dr. Alauddin Ahmed Prof. Dr. Donald J. Siegel Prof. Dr. Adam J. Matzger Department of Chemistry and Macromolecular Science and Engineering Program University of Michigan 930 North University Avenue Ann Arbor MI 48109 USA Mechanical Engineering Department University of Michigan Ann Arbor MI 48109 USA Materials Science and Engineering Applied Physics Program and University of Michigan Energy Institute University of Michigan Ann Arbor MI 48109 USA Current address: Walker Department of Mechanical Engineering Texas Materials Institute and Oden Institute for Computational Engineering and Sciences University of Texas at Austin 204 E. Dean Keeton Street ETC II 5.160 Austin TX 78712-1591 USA

Remarkable methane uptake is demonstrated experimentally in three metal-organic frameworks (MOFs) identified by computational screening: UTSA-76, UMCM-152 and DUT-23-Cu. These MOFs outperform the benchmark sorbent, HKUST-1, both volumetrically and gravimetrically, under a pressure swing of 80 to 5 bar at 298 K. Although high uptake at elevated pressure is critical for achieving this performance, a low density of high-affinity sites (coordinatively unsaturated metal centers) also contributes to a more complete release of stored gas at low pressure. The identification of these MOFs facilitates the efficient storage of natural gas via adsorption and provides further evidence of the utility of computational screening in identifying overlooked sorbents.

关键词： computational Screening Deliverable Capacity Interatomic Potentials Metal Organic Framework (MOF) Methane Storage

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Ab Initio Calculation on Spectroscopic Properties and Radiative Lifetimes of Low-Lying Excited States of NaK

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Chinese Journal of Chemical physics 2019年第6期32卷 667-673,I0002页

作者： Shi-yang Zhang Feng Xie Feng-dong Jia Xiao-kang Li Ru-quan Wang Rui Li Yong Wu Zhi-ping Zhong School of Physics University of Chinese Academy of SciencesBeijing 100049China Institute of Nuclear and New Energy Technology Collaborative Innovation Center of Advanced Nuclear Energy TechnologyKey Laboratory of Advanced Reactor Engineering and Safety of Ministry of EducationTsinghua UniversityBeijing 100084China Institute of Physics Chinese Academy of SciencesBeijing 100190China Data Center for High Energy Density Physics Institute of Applied Physics and Computational MathematicsBeijing 100088China Department of Physics College of ScienceQiqihar UniversityQiqihar 161006China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China

We performed high-level ab initio calculations on electronic structure of Na K. The potential energy curves (PECs) of 10 Λ-S states correlated with the three lowest dissociation limits have been calculated. On the basis of the calculated PECs, the spectroscopic constants of the boundΛ-S states are obtained, which are in good agreement with experimental results. The maximum vibrational quantum numbers of the singlet ground state X^1Σ^+ and the triplet ground state a^3Σ^+ have been analyzed with the semiclassical scattering theory. Transition properties including transition dipole moments, Franck-Condon factors, and radiative lifetimes have been investigated. The research results indicate that such calculations can provide fairly reliable estimation of parameters for the ultracold alkali diatomic molecular experiment.

关键词： Ultracold dipolar molecule Transition dipole moment Spectroscopic constants Potential curves

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Coherent-State Approach for Majorana Representation

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Communications in Theoretical physics 2017年第6期67卷 611-618页

作者：刘昊迪傅立斌王晓光 Beijing Computational Science Research Center Center for Quantum Sciences and School of Physics Northeast Normal University National Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics Zhejiang Institute of Modern Physics Department of PhysicsZhejiang University

By representing a quantum state and its evolution with the Majorana stars on the Bloch sphere, the Majorana representation provides us an intuitive way to study a physical system with SU(2) symmetry. In this work,based on coherent states, we propose a method to establish the generalization of Majorana representation for a general symmetry. By choosing a generalized coherent state as a reference state, we give a more general Majorana representation for both finite and infinite systems and the corresponding star equations are given. Using this method, we study the squeezed vacuum states for three different symmetries, Heisenberg–Weyl, SU(2) and SU(1,1), and express the effect of squeezing parameter on the distribution of stars. Furthermore, we also study the dynamical evolution of stars for an initial coherent state driven by a nonlinear Hamiltonian, and find that at a special time point, the stars are distributed on two orthogonal large circles.

关键词： majorana representation coherent state squeezed states SU(1,1) symmetry

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Cross-correlation of Dark Energy Survey Year 3 lensing data with ACT and Planck thermal Sunyaev-Zel’dovich effect observations. II. Modeling and constraints on halo pressure profiles

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Physical Review D 2022年第12期105卷 123526-123526页

作者： S. Pandey M. Gatti E. Baxter J. C. Hill X. Fang C. Doux G. Giannini M. Raveri J. DeRose H. Huang E. Moser N. Battaglia A. Alarcon A. Amon M. Becker A. Campos C. Chang R. Chen A. Choi K. Eckert J. Elvin-Poole S. Everett A. Ferte I. Harrison N. Maccrann J. Mccullough J. Myles A. Navarro Alsina J. Prat R. P. Rollins C. Sanchez T. Shin M. Troxel I. Tutusaus B. Yin M. Aguena S. Allam F. Andrade-Oliveira G. M. Bernstein E. Bertin B. Bolliet J. R. Bond D. Brooks E. Calabrese A. Carnero Rosell M. Carrasco Kind J. Carretero R. Cawthon M. Costanzi M. Crocce L. N. da Costa M. E. S. Pereira J. De Vicente S. Desai H. T. Diehl J. P. Dietrich P. Doel J. Dunkley A. E. Evrard S. Ferraro I. Ferrero B. Flaugher P. Fosalba J. García-Bellido E. Gaztanaga D. W. Gerdes T. Giannantonio D. Gruen R. A. Gruendl J. Gschwend G. Gutierrez K. Herner A. D. Hincks S. R. Hinton D. L. Hollowood K. Honscheid J. P. Hughes D. Huterer B. Jain D. J. James T. Jeltema E. Krause K. Kuehn O. Lahav M. Lima M. Lokken M. S. Madhavacheril M. A. G. Maia J. J. Mcmahon P. Melchior F. Menanteau R. Miquel J. J. Mohr K. Moodley R. Morgan F. Nati M. D. Niemack L. Page A. Palmese F. Paz-Chinchón A. Pieres A. A. Plazas Malagón M. Rodriguez-Monroy A. K. Romer E. Sanchez V. Scarpine E. Schaan S. Serrano I. Sevilla-Noarbe E. Sheldon B. D. Sherwin C. Sifón M. Smith M. Soares-Santos D. Spergel E. Suchyta M. E. C. Swanson G. Tarle D. Thomas C. To T. N. Varga J. Weller E. J. Wollack Z. Xu Department of Physics and Astronomy University of Pennsylvania Philadelphia Pennsylvania 19104 USA Institute for Astronomy University of Hawai’i 2680 Woodlawn Drive Honolulu Hawai’i 96822 USA Department of Physics Columbia University New York New York 10027 USA Center for Computational Astrophysics Flatiron Institute New York New York 10010 USA Department of Astronomy/Steward Observatory University of Arizona 933 North Cherry Avenue Tucson Arizona 85721-0065 USA Institut de Física d’Altes Energies (IFAE) The Barcelona Institute of Science and Technology Campus UAB 08193 Bellaterra (Barcelona) Spain Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley California 94720 USA Department of Physics University of Arizona Tucson Arizona 85721 USA Department of Astronomy Cornell University Ithaca New York 14853 USA Argonne National Laboratory 9700 South Cass Avenue Lemont Illinois 60439 USA Kavli Institute for Particle Astrophysics and Cosmology P. O. Box 2450 Stanford University Stanford California 94305 USA Department of Physics Carnegie Mellon University Pittsburgh Pennsylvania 15312 USA Department of Astronomy and Astrophysics University of Chicago Chicago Illinois 60637 USA Kavli Institute for Cosmological Physics University of Chicago Chicago Illinois 60637 USA Department of Physics Duke University Durham North Carolina 27708 USA Center for Cosmology and Astro-Particle Physics The Ohio State University Columbus Ohio 43210 USA Department of Physics The Ohio State University Columbus Ohio 43210 USA Santa Cruz Institute for Particle Physics Santa Cruz California 95064 USA Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Pasadena California 91109 USA Department of Physics University of Oxford Denys Wilkinson Building Keble Road Oxford OX1 3RH United Kingdom Jodrell Bank Center for Astrophysics School of Physics and Astronomy University of Manchester Oxford Road Manchester M13 9PL United Kin

Hot, ionized gas leaves an imprint on the cosmic microwave background via the thermal Sunyaev-Zel’dovich (tSZ) effect. The cross-correlation of gravitational lensing (which traces the projected mass) with the tSZ effect (which traces the projected gas pressure) is a powerful probe of the thermal state of ionized baryons throughout the Universe and is sensitive to effects such as baryonic feedback. In a companion paper (Gatti et al. Phys. Rev. D 105, 123525 (2022)), we present tomographic measurements and validation tests of the cross-correlation between Galaxy shear measurements from the first three years of observations of the Dark Energy Survey and tSZ measurements from a combination of Atacama Cosmology Telescope and Planck observations. In this work, we use the same measurements to constrain models for the pressure profiles of halos across a wide range of halo mass and redshift. We find evidence for reduced pressure in low-mass halos, consistent with predictions for the effects of feedback from active Galactic nuclei. We infer the hydrostatic mass bias (B≡M500c/MSZ) from our measurements, finding B=1.8±0.1 when adopting the Planck-preferred cosmological parameters. We additionally find that our measurements are consistent with a nonzero redshift evolution of B, with the correct sign and sufficient magnitude to explain the mass bias necessary to reconcile cluster count measurements with the Planck-preferred cosmology. Our analysis introduces a model for the impact of intrinsic alignments (IAs) of galaxy shapes on the shear-tSZ correlation. We show that IA can have a significant impact on these correlations at current noise levels.

关键词： Cosmic microwave background Cosmological parameters Gravitational lenses Large scale structure of the Universe Optical, UV, & IR astronomy

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Probabilistic Theory of Mean Field Games with Applications I 1

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丛书名： Probability Theory and Stochastic Modelling

2018年

作者： René Carmona François Delarue

ISBN: (数字)9783319589206

ISBN: (纸本)9783319564371;9783030132606

Volume I of the book is entirely devoted to the theory of mean field games without a common noise. The first half of the volume provides a self-contained introduction to mean field games, starting from concrete illustrations of games with a finite number of players, and ending with ready-for-use solvability results. Readers are provided with the tools necessary for the solution of forward-backward stochastic differential equations of the McKean-Vlasov type at the core of the probabilistic approach. The second half of this volume focuses on the main principles of analysis on the Wasserstein space. It includes Lions' approach to the Wasserstein differential calculus, and the applications of its results to the analysis of stochastic mean field control problems.

关键词： Probability Theory Calculus of Variations and Optimization Differential Equations Quantitative Economics

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The Athena++ adaptive mesh refinement framework: Design and magnetohydrodynamic solvers

arXiv

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arXiv 2020年

作者： Stone, James M. Tomida, Kengo White, Christopher J. Felker, Kyle G. Department of Astrophysical Sciences Princeton University PrincetonNJ08544 United States Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Department of Earth and Space Science Osaka University Toyonaka Osaka560-0043 Japan Kavli Institute for Theoretical Physics University of California Santa Barbara Santa BarbaraCA93107 United States School of Natural Sciences Institute for Advanced Study PrincetonNJ08544 United States Astronomical Institute Tohoku University Sendai Miyagi980-8578 Japan Argonne National Laboratory LemontIL60439 United States

The design and implementation of a new framework for adaptive mesh refinement (AMR) calculations is described. It is intended primarily for applications in astrophysical fluid dynamics, but its flexible and modular design enables its use for a wide variety of physics. The framework works with both uniform and nonuniform grids in Cartesian and curvilinear coordinate systems. It adopts a dynamic execution model based on a simple design called a "task list" that improves parallel performance by overlapping communication and computation, simplifies the inclusion of a diverse range of physics, and even enables multiphysics models involving different physics in different regions of the calculation. We describe physics modules implemented in this framework for both non-relativistic and relativistic magnetohydrodynamics (MHD). These modules adopt mature and robust algorithms originally developed for the Athena MHD code and incorporate new extensions: support for curvilinear coordinates, higher-order time integrators, more realistic physics such as a general equation of state, and diffusion terms that can be integrated with super-time-stepping algorithms. The modules show excellent performance and scaling, with well over 80% parallel efficiency on over half a million threads. The source code has been made publicly available. Copyright © 2020, The Authors. All rights reserved.

关键词： Magnetohydrodynamics

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The atacama cosmology telescope: Summary of dr4 and dr5 data products and data access

arXiv

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arXiv 2021年

作者： Mallaby-Kay, Maya Atkins, Zachary Aiola, Simone Amodeo, Stefania Austermann, Jason E. Beall, James A. Becker, Daniel T. Bond, J. Richard Calabrese, Erminia Chesmore, Grace E. Choi, Steve K. Crowley, Kevin T. Darwish, Omar Denison, Edward V. Devlin, Mark J. Duff, Shannon M. Duivenvoorden, Adriaan J. Dunkley, Jo Ferraro, Simone Fichman, Kyra Gallardo, Patricio A. Golec, Joseph E. Guan, Yilun Han, Dongwon Hasselfield, Matthew Hill, J. Colin Hilton, Gene C. Hilton, Matt Hložek, Renée Hubmayr, Johannes Huffenberger, Kevin M. Hughes, John P. Koopman, Brian J. Louis, Thibaut MacInnis, Amanda Madhavacheril, Mathew S. McMahon, Jeff Moodley, Kavilan Naess, Sigurd Namikawa, Toshiya Nati, Federico Newburgh, Laura B. Nibarger, John P. Niemack, Michael D. Page, Lyman A. Salatino, Maria Schaan, Emmanuel Schillaci, Alessandro Sehgal, Neelima Sherwin, Blake D. Sifón, Cristóbal Simon, Sara Staggs, Suzanne T. Storer, Emilie R. Ullom, Joel N. Van Engelen, Alexander Van Lanen, Jeff Vale, Leila R. Wollack, Edward J. Xu, Zhilei Department of Astronomy University of Chicago ChicagoIL United States Joseph Henry Laboratories of Physics Jadwin Hall Princeton University PrincetonNJ08544 United States Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Department of Astronomy Cornell University IthacaNY14853 United States NIST Quantum Devices Group 325 Broadway Mailcode 817.03 BoulderCO80305 United States Canadian Institute for Theoretical Astrophysics University of Toronto 60 St. George Street TorontoONM5S 3H8 Canada School of Physics and Astronomy Cardiff University The Parade CardiffCF24 3AA United Kingdom Department of Physics University of Chicago ChicagoIL60637 United States Department of Physics Cornell University IthacaNY14853 United States Department of Physics University of California Berkeley LeConte Hall BerkeleyCA94720 United States Department of Applied Mathematics and Theoretical Physics University of Cambridge Wilberforce Road CambridgeCB3 0WA United Kingdom Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street PhiladelphiaPA19104 United States Department of Astrophysical Sciences Peyton Hall Princeton University PrincetonNJ08544 United States Lawrence Berkeley National Laboratory One Cyclotron Road BerkeleyCA94720 United States Department of Physics University of Michigan Ann ArborUSA48103 United States Department of Physics and Astronomy University of Pittsburgh PittsburghPA15260 United States Physics and Astronomy Department Stony Brook University Stony BrookNY11794 United States Department of Physics Columbia University 538 West 120th Street New YorkNY10027 United States Center for Computational Astrophysics Flatiron Institute New YorkNY10003 United States Astrophysics Research Centre University of KwaZulu-Natal Westville Campus Durban4041 South Africa School of Mathematics Statistics and Computer Science University of KwaZulu-Natal We

Two recent large data releases for the Atacama Cosmology Telescope (ACT), called DR4 and DR5, are available for public access. These data include temperature and polarization maps that cover nearly half the sky at arcminute resolution in three frequency bands;lensing maps and componentseparated maps covering ∼ 2,100 deg2 of sky;derived power spectra and cosmological likelihoods;a catalog of over 4,000 galaxy clusters;and supporting ancillary products including beam functions and masks. The data and products are described in a suite of ACT papers;here we provide a summary. In order to facilitate ease of access to these data we present a set of Jupyter IPython notebooks developed to introduce users to DR4, DR5, and the tools needed to analyze these data. The data products (excluding simulations) and the set of notebooks are publicly available on the NASA Legacy Archive for Microwave Background Data Analysis (LAMBDA);simulation products are available on the National Energy Research Scientific Computing Center (NERSC). © 2021, CC BY.

关键词： NASA

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Diffusion dynamics of a conductance-based neuronal population

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Physical Review E 2019年第4期99卷 042307-042307页

作者： Argha Mondal Sanjeev Kumar Sharma Ranjit Kumar Upadhyay M. A. Aziz-Alaoui Prosenjit Kundu Chittaranjan Hens Department of Applied Mathematics Indian Institute of Technology (Indian School of Mines) Dhanbad 826004 India Computational Neuroscience Center University of Washington Seattle Washington 98195 USA UniHavre LMAH CNRS No. 3335 ISCN Normandie University 76600 Le Havre France National Institute of Technology Durgapur Durgapur West Bengal 713209 India Physics and Applied Mathematics Unit Indian Statistical Institute Barrackpore Trunk Road Kolkata West Bengal 700108 India

We study the spatiotemporal dynamics of a conductance-based neuronal cable. The processes of one-dimensional (1D) and 2D diffusion are considered for a single variable, which is the membrane voltage. A 2D Morris-Lecar (ML) model is introduced to investigate the nonlinear responses of an excitable conductance-based neuronal cable. We explore the parameter space of the uncoupled ML model and, based on the bifurcation diagram (as a function of stimulus current), we analyze the 1D diffusion dynamics in three regimes: phasic spiking, coexistence states (tonic spiking and phasic spiking exist together), and a quiescent state. We show (depending on parameters) that the diffusive system may generate regular and irregular bursting or spiking behavior. Further, we explore a 2D diffusion acting on the membrane voltage, where striped and hexagonlike patterns can be observed. To validate our numerical results and check the stability of the existing patterns generated by 2D diffusion, we use amplitude equations based on multiple-scale analysis. We incorporate 1D diffusion in an extended 3D version of the ML model, in which irregular bursting emerges for a certain diffusion strength. The generated patterns may have potential applications in nonlinear neuronal responses and signal transmission.

关键词： Bifurcations Emergence of patterns Neuronal networks Pattern formation

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