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Correction to: Air change rate effects on the airborne diseases spreading in Underground Metro wagons

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Environmental science and pollution research international 2021年第24期28卷 31908页

作者： Mostafa El-Salamony Ahmed Moharam Amr Guaily Mohammed A Boraey Aerospace Department College of Engineering Peking University Beijing 100871 China. elsalamony.mostafa@***. Smart Engineering Systems Research Center (SESC) Nile University Sheikh Zayed City 12588 Egypt. Department of Engineering Mathematics and Physics Faculty of Engineering Cairo University Giza 12613 Egypt. Mechanical Engineering Program School of Engineering and Applied Sciences Nile University Sheikh Zayed City 12588 Egypt. Mechanical Power Engineering Department Zagazig University Zagazig 44519 Egypt.

A Correction to this paper has been published: https://***/10.1007/s11356-021-13405-8

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Setting the physical scale of dimensional reduction in causal dynamical triangulations

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arXiv 2018年

作者： Cooperman, Joshua H. Dorghabekov, Manuchehr Department of Physics and Astronomy Bucknell University LewisburgPA United States Physics Program Bard College Annandale-on-Hudson NY United States Applied Mathematics and Informatics Program American University of Central Asia Bishkek Kyrgyzstan

Within the causal dynamical triangulations approach to the quantization of gravity, striking evidence has emerged for the dynamical reduction of spacetime dimension on sufficiently small scales. Specifically, the spectral dimension decreases from the topological value of 4 towards a value near 2 as the scale being probed decreases. The physical scales over which this dimensional reduction occurs have not previously been ascertained. We present and implement a method to determine these scales in units of either the Planck length or the quantum spacetime geometry’s effective de Sitter length. We find that dynamical reduction of the spectral dimension occurs over physical scales of the order of 10 Planck lengths, which, for the numerical simulation considered below, corresponds to the order of 10−1 de Sitter lengths. Copyright © 2018, The Authors. All rights reserved.

关键词： Triangulation

Finite-temperature infrared and Raman spectra of high-pressure hydrogen from first-principles molecular dynamics

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Physical Review B 2018年第14期98卷 144301-144301页

作者： Chunyi Zhang Cui Zhang Mohan Chen Wei Kang Zhuowei Gu Jianheng Zhao Cangli Liu Chengwei Sun Ping Zhang HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing 100871 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Physics Temple University Philadelphia Pennsylvania 19122 USA Collaborative Innovation Center of IFSA Shanghai Jiao Tong University Shanghai 200240 China Institute of Fluid Physics China Academy of Engineering Physics Mianyang 621900 China

Finite-temperature infrared and Raman spectra of theoretically proposed stable structures C2/c and Pc of high-pressure solid hydrogen are calculated from time correlation functions of dipole moments and polarizabilities extracted from first-principles molecular dynamics simulations. Calculated spectra are much improved compared with those obtained from density functional perturbation theory at zero temperature, which suggests the significance of finite-temperature effects in both spectra. The excellent agreement between the calculated spectra of the C2/c structure and experimental results supports the theory that C2/c is the structure of phase III. The high-frequency Raman vibron mode of the Pc structure is also well reproduced compared with experimental spectra. However, the energy of the low-frequency Raman vibron mode of the Pc structure is underestimated up to 16%. This suggests that the atomic structure of the strongly bonded layer in phase IV is well predicted, while the weakly bonded layer still differs from the real structure somehow. In addition, we find that diffusion in the weakly bonded layer of the Pc structure is strong and the layer displays several features of a two-dimensional liquid.

关键词： First order phase transitions Lattice dynamics Solid-solid transformations Structural phase transition Molecular solids Density functional theory Infrared spectroscopy Molecular dynamics

Atacama Cosmology Telescope: Component-separated maps of CMB temperature and the thermal Sunyaev-Zel’dovich effect

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Physical Review D 2020年第2期102卷 023534-023534页

作者： Mathew S. Madhavacheril J. Colin Hill Sigurd Næss Graeme E. Addison Simone Aiola Taylor Baildon Nicholas Battaglia Rachel Bean J. Richard Bond Erminia Calabrese Victoria Calafut Steve K. Choi Omar Darwish Rahul Datta Mark J. Devlin Joanna Dunkley Rolando Dünner Simone Ferraro Patricio A. Gallardo Vera Gluscevic Mark Halpern Dongwon Han Matthew Hasselfield Matt Hilton Adam D. Hincks Renée Hložek Shuay-Pwu Patty Ho Kevin M. Huffenberger John P. Hughes Brian J. Koopman Arthur Kosowsky Martine Lokken Thibaut Louis Marius Lungu Amanda MacInnis Loïc Maurin Jeffrey J. McMahon Kavilan Moodley Federico Nati Michael D. Niemack Lyman A. Page Bruce Partridge Naomi Robertson Neelima Sehgal Emmanuel Schaan Alessandro Schillaci Blake D. Sherwin Cristóbal Sifón Sara M. Simon David N. Spergel Suzanne T. Staggs Emilie R. Storer Alexander van Engelen Eve M. Vavagiakis Edward J. Wollack Zhilei Xu Centre for the Universe Perimeter Institute for Theoretical Physics Waterloo Ontario Canada N2L 2Y5 Department of Astrophysical Sciences Princeton University 4 Ivy Lane Princeton New Jersey 08544 USA Department of Physics Columbia University 550 West 120th Street New York New York 10027 USA Center for Computational Astrophysics Flatiron Institute 162 5th Avenue New York New York 10010 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08540 USA Department of Physics and Astronomy Johns Hopkins University Baltimore Maryland 21218 USA Department of Physics University of Michigan Ann Arbor Michigan 48103 USA Department of Astronomy Cornell University Ithaca New York 14853 USA Canadian Institute for Theoretical Astrophysics University of Toronto 60 St. George St. Toronto Ontario M5S 3H8 Canada School of Physics and Astronomy Cardiff University The Parade Cardiff CF24 3AA United Kingdom Department of Applied Mathematics and Theoretical Physics University of Cambridge Wilberforce Road Cambridge CB3 0WA United Kingdom Department of Physics and Astronomy University of Pennsylvania 209 South 33rd Street Philadelphia Pennsylvania 19104 USA Joseph Henry Laboratories of Physics Jadwin Hall Princeton University Princeton New Jersey 08544 USA Instituto de Astrofísica and Centro de Astro-Ingeniería Facultad de Física Pontificia Universidad Católica de Chile Av. Vicuña Mackenna 4860 7820436 Macul Santiago Chile Physics Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Department of Physics Cornell University 109 Clark Hall Ithaca New York 14853 USA Department of Physics and Astronomy University of Southern California Los Angeles California 90089-0484 USA Department of Physics and Astronomy University of British Columbia Vancouver British Columbia Canada V6T 1Z1 Physics and Astronomy Department Stony Brook University Stony Brook New York 11794 USA Astrophysics & Cosmology Research Unit Sc

Optimal analyses of many signals in the cosmic microwave background (CMB) require map-level extraction of individual components in the microwave sky, rather than measurements at the power spectrum level alone. To date, nearly all map-level component separation in CMB analyses has been performed exclusively using satellite data. In this paper, we implement a component separation method based on the internal linear combination (ILC) approach which we have designed to optimally account for the anisotropic noise (in the 2D Fourier domain) often found in ground-based CMB experiments. Using this method, we combine multifrequency data from the Planck satellite and the Atacama Cosmology Telescope Polarimeter (ACTPol) to construct the first wide-area (≈2100 sq. deg.), arcminute-resolution component-separated maps of the CMB temperature anisotropy and the thermal Sunyaev-Zel’dovich (tSZ) effect sourced by the inverse-Compton scattering of CMB photons off hot, ionized gas. Our ILC pipeline allows for explicit deprojection of various contaminating signals, including a modified blackbody approximation of the cosmic infrared background (CIB) spectral energy distribution. The cleaned CMB maps will be a useful resource for CMB lensing reconstruction, kinematic SZ cross-correlations, and primordial non-Gaussianity studies. The tSZ maps will be used to study the pressure profiles of galaxies, groups, and clusters through cross-correlations with halo catalogs, with dust contamination controlled via CIB deprojection. The data products described in this paper are available on LAMBDA.

关键词： Cosmic microwave background Cosmology

Heterogeneous multireference alignment for images with application to 2-D classification in single particle reconstruction

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arXiv 2018年

作者： Ma, Chao Bendory, Tamir Boumal, Nicolas Sigworth, Fred Singer, Amit Program in Applied and Computational Mathematics Princeton University PrincetonNJ United States Department of Mathematics Princeton University PrincetonNJ United States Department of Cellular and Molecular Physiology Yale University School of Medicine New HavenCT United States

Motivated by the task of 2-D classification in single particle reconstruction by cryo-electron microscopy (cryo-EM), we consider the problem of heterogeneous multireference alignment of images. In this problem, the goal is to estimate a (typically small) set of target images from a (typically large) collection of observations. Each observation is a rotated, noisy version of one of the target images. For each individual observation, neither the rotation nor which target image has been rotated are known. As the noise level in cryo-EM data is high, clustering the observations and estimating individual rotations is challenging. We propose a framework to estimate the target images directly from the observations, completely bypassing the need to cluster or register the images. The framework consists of two steps. First, we estimate rotation-invariant features of the images, such as the bispectrum. These features can be estimated to any desired accuracy, at any noise level, provided sufficiently many observations are collected. Then, we estimate the images from the invariant features. Numerical experiments on synthetic cryo-EM datasets demonstrate the effectiveness of the method. Ultimately, we outline future developments required to apply this method to experimental data. Copyright © 2018, The Authors. All rights reserved.

关键词： Alignment

Euclid Quick Data Release (Q1). The Strong Lensing Discovery Engine C - Finding lenses with machine learning

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arXiv 2025年

作者： Lines, N.E.P. Collett, T.E. Walmsley, M. Rojas, K. Li, T. Leuzzi, L. Manjón-García, A. Vincken, S.H. Wilde, J. Holloway, P. Verma, A. Metcalf, R.B. Andika, I.T. Melo, A. Melchior, M. Domínguez Sánchez, H. Díaz-Sánchez, A. Acevedo Barroso, J.A. Clément, B. Krawczyk, C. Pearce-Casey, R. Serjeant, S. Courbin, F. Despali, G. Gavazzi, R. Schuldt, S. Degaudenzi, H. Ecker, L.R. Enzi, W.J.R. Finner, K. Galan, A. Giocoli, C. Hogg, N.B. Jahnke, K. Kruk, S. Mahler, G. More, A. Nagam, B.C. Pearson, J. Sainz de Murieta, A. Scarlata, C. Sluse, D. Sonnenfeld, A. Spiniello, C. Thai, T.T. Tortora, C. Ulivi, L. Weisenbach, L. Zumalacarregui, M. Aghanim, N. Altieri, B. Amara, A. Andreon, S. Auricchio, N. Aussel, H. Baccigalupi, C. Baldi, M. Balestra, A. Bardelli, S. Battaglia, P. Bender, R. Bernardeau, F. Biviano, A. Bonchi, A. Bonino, D. Branchini, E. Brescia, M. Brinchmann, J. Camera, S. Cañas-Herrera, G. Capobianco, V. Carbone, C. Cardone, V.F. Carretero, J. Casas, S. Castellano, M. Castignani, G. Cavuoti, S. Chambers, K.C. Cimatti, A. Colodro-Conde, C. Congedo, G. Conselice, C.J. Conversi, L. Copin, Y. Costille, A. Courtois, H.M. Cropper, M. Da Silva, A. De Lucia, G. Di Giorgio, A.M. Dolding, C. Dole, H. Dubath, F. Duncan, C.A.J. Dupac, X. Escoffier, S. Fabricius, M. Farina, M. Farinelli, R. Faustini, F. Ferriol, S. Finelli, F. Fotopoulou, S. Frailis, M. Franceschi, E. Fumana, M. Galeotta, S. George, K. Gillard, W. Gillis, B. Gómez-Alvarez, P. Gracia-Carpio, J. Granett, B.R. Grazian, A. Grupp, F. Guzzo, L. Gwyn, S. Haugan, S.V.H. Holmes, W. Hook, I.M. Hormuth, F. Hornstrup, A. Hudelot, P. Jhabvala, M. Keihänen, E. Kermiche, S. Kiessling, A. Kubik, B. Kümmel, M. Kunz, M. Kurki-Suonio, H. Le Boulc’h, Q. Le Brun, A.M.C. Le Mignant, D. Ligori, S. Lilje, P.B. Lindholm, V. Lloro, I. Mainetti, G. Maino, D. Maiorano, E. Mansutti, O. Marcin, S. Marggraf, O. Martinelli, M. Martinet, N. Marulli, F. Massey, R. Institute of Cosmology and Gravitation University of Portsmouth PortsmouthPO1 3FX United Kingdom David A. Dunlap Department of Astronomy & Astrophysics University of Toronto 50 St George Street TorontoONM5S 3H4 Canada Jodrell Bank Centre for Astrophysics Department of Physics and Astronomy University of Manchester Oxford Road ManchesterM13 9PL United Kingdom University of Applied Sciences and Arts of Northwestern Switzerland School of Engineering Windisch5210 Switzerland Dipartimento di Fisica e Astronomia "Augusto Righi" Alma Mater Studiorum Università di Bologna via Piero Gobetti 93/2 Bologna40129 Italy INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna Via Piero Gobetti 93/3 Bologna40129 Italy Departamento Física Aplicada Universidad Politécnica de Cartagena Campus Muralla del Mar Murcia Cartagena30202 Spain Martí i Franquès 1 Barcelona08028 Spain Department of Physics Oxford University Keble Road OxfordOX1 3RH United Kingdom Technical University of Munich TUM School of Natural Sciences Physics Department James-Franck-Str. 1 Garching85748 Germany Max-Planck-Institut für Astrophysik Karl-Schwarzschild-Str. 1 Garching85748 Germany Instituto de Física de Cantabria Edificio Juan Jordá Avenida de los Castros Santander39005 Spain Observatoire de Sauverny Versoix1290 Switzerland Lausanne1015 Switzerland School of Physical Sciences The Open University Milton KeynesMK7 6AA United Kingdom Passeig de Lluís Companys 23 Barcelona08010 Spain INFN-Sezione di Bologna Viale Berti Pichat 6/2 Bologna40127 Italy Aix-Marseille Université CNRS CNES LAM Marseille France Institut d’Astrophysique de Paris UMR 7095 CNRS Sorbonne Université 98 bis boulevard Arago Paris75014 France Dipartimento di Fisica "Aldo Pontremoli" Università degli Studi di Milano Via Celoria 16 Milano20133 Italy INAF-IASF Milano Via Alfonso Corti 12 Milano20133 Italy Department of Astronomy University of Geneva ch. d’Ecogia 16 Versoix1290 Sw

Strong gravitational lensing has the potential to provide a powerful probe of astrophysics and cosmology, but fewer than 1000 strong lenses have been confirmed previously. With 0′′ . 16 resolution covering a third of the sky, the Euclid telescope will revolutionise strong lens finding, with 170 000 lenses forecasted to be discovered amongst its 1.5 billion galaxies. We present an analysis of the performance of five machine-learning models at finding strong gravitational lenses in the quick release of Euclid data (Q1), covering 63 deg2. The models are validated with citizen scientists and expert visual inspection. We focus on the best performing network: a fine-tuned version of the Zoobot pretrained model, originally trained to classify galaxy morphologies in heterogeneous astronomical imaging surveys. Of the one million Q1 objects that Zoobot was tasked to find strong lenses within, the top 1000 ranked objects contained 122 grade A lenses (almost certain lenses), and 41 grade B lenses (probable lenses). A deeper search with the five networks combined with visual inspection discovered 250 (247) grade A (B) lenses, of which 224 (182) are ranked in the top 20 000 by Zoobot. When extrapolated to the full Euclid survey, the highest ranked one million images will contain 75 000 grade A or B strong gravitational lenses. © 2025, CC BY.

关键词： Cosmology

Collision cross sections of N2 by H+ impact at keV energies within time-dependent density-functional theory

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Physical Review A 2018年第3期97卷 032706-032706页

作者： W. Yu C.-Z. Gao Y. Zhang F. S. Zhang R. Hutton Y. Zou B. Wei Institute of Modern Physics Department of Nuclear Science and Technology Fudan University Shanghai 200433 China Key Laboratory of Nuclear Physics and Ion-beam Application (MOE) Fudan University Shanghai 200433 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China College of Nuclear Science and Technology Beijing Normal University Beijing 100875 China

We calculate electron capture and ionization cross sections of N2 impacted by the H+ projectile at keV energies. To this end, we employ the time-dependent density-functional theory coupled nonadiabatically to molecular dynamics. To avoid the explicit treatment of the complex density matrix in the calculation of cross sections, we propose an approximate method based on the assumption of constant ionization rate over the period of the projectile passing the absorbing boundary. Our results agree reasonably well with experimental data and semi-empirical results within the measurement uncertainties in the considered energy range. The discrepancies are mainly attributed to the inadequate description of exchange-correlation functional and the crude approximation for constant ionization rate. Although the present approach does not predict the experiments quantitatively for collision energies below 10 keV, it is still helpful to calculate total cross sections of ion-molecule collisions within a certain energy range.

关键词： Atomic & molecular collisions Electronic excitation & ionization

Effect of imperfections on the hyperuniformity of many-body systems

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Physical Review B 2018年第5期97卷 054105-054105页

作者： Jaeuk Kim Salvatore Torquato Department of Physics Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA

A hyperuniform many-body system is characterized by a structure factor Sk that vanishes in the small-wave-number limit or equivalently by a local number variance σN2R associated with a spherical window of radius R that grows more slowly than Rd in the large-R limit. Thus, the hyperuniformity implies anomalous suppression of long-wavelength density fluctuations relative to those in typical disordered systems, i.e., σN2R∼Rd as R→∞. Hyperuniform systems include perfect crystals, quasicrystals, and special disordered systems. Disordered hyperuniform systems are amorphous states of matter that lie between a liquid and crystal [S. Torquato et al., Phys. Rev. X 5, 021020 (2015)], and have been the subject of many recent investigations due to their novel properties. In the same way that there is no perfect crystal in practice due to the inevitable presence of imperfections, such as vacancies and dislocations, there is no “perfect” hyperuniform system, whether it is ordered or not. Thus, it is practically and theoretically important to quantitatively understand the extent to which imperfections introduced in a perfectly hyperuniform system can degrade or destroy its hyperuniformity and corresponding physical properties. This paper begins such a program by deriving explicit formulas for Sk in the small-wave-number regime for three types of imperfections: (1) uncorrelated point defects, including vacancies and interstitials, (2) stochastic particle displacements, and (3) thermal excitations in the classical harmonic regime. We demonstrate that our results are in excellent agreement with numerical simulations. We find that “uncorrelated” vacancies or interstitials destroy hyperuniformity in proportion to the defect concentration p. We show that “uncorrelated” stochastic displacements in perfect lattices can never destroy the hyperuniformity but it can be degraded such that the perturbed lattices fall into class III hyperuniform systems, where σN2R∼Rd−α as R→∞ and 0<α<1. By cont

关键词： Interstitials Structural properties Vacancies

The observational uncertainty of coronal hole boundaries in automated detection schemes

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arXiv 2021年

作者： Reiss, Martin A. Muglach, Karin Möstl, Christian Arge, Charles N. Bailey, Rachel Delouille, Véronique Garton, Tadhg M. Hamada, Amr Hofmeister, Stefan Illarionov, Egor Jarolim, Robert Kirk, Michael S.F. Kosovichev, Alexander Krista, Larisza Lee, Sangwoo Lowder, Chris MacNeice, Peter J. Veronig, Astrid Space Research Institute Austrian Academy of Sciences Graz Austria Heliophysics Science Division NASA Goddard Space Flight Center GreenbeltMD20771 United States Catholic University of America WashingtonDC20064 United States Conrad Observatory Zentralanstalt für Meteorologie und Geodynamik Vienna Austria Royal Observatory of Belgium Brussels Belgium University of Southampton Southampton United Kingdom Space Physics and Astronomy Research Unit Space Climate Group University of Oulu Oulu Finland University of Graz Institute of Physics Graz Austria Columbia Astrophysics Laboratory Columbia University New YorkNY10027 United States Moscow State University Moscow119991 Russia Moscow Center of Fundamental and Applied Mathematics Moscow119234 Russia ASTRA llc LouisvilleCO80027 United States Center for Computational Heliophysics New Jersey Institute of Technology NewarkNJ07102 United States Department of Physics New Jersey Institute of Technology NewarkNJ07102 United States NASA Ames Research Center Moffett FieldCA94035 United States Cooperative Institute for Research in Environmental Sciences University of Colorado BoulderCO80309 United States National Centers for Environmental Information National Oceanic and Atmospheric Administration BoulderCO80305 United States Korean Space Weather Center Jeju Korea Republic of Southwest Research Institute BoulderCO United States Kanzelhöhe Observatory for Solar and Environmental Research University of Graz Graz Austria

Coronal holes are the observational manifestation of the solar magnetic field open to the heliosphere and are of pivotal importance for our understanding of the origin and acceleration of the solar wind. Observations from space missions such as the Solar Dynamics Observatory now allow us to study coronal holes in unprecedented detail. Instrumental effects and other factors, however, pose a challenge to automatically detect coronal holes in solar imagery. The science community addresses these challenges with different detection schemes. Until now, little attention has been paid to assessing the disagreement between these schemes. In this COSPAR ISWAT initiative, we present a comparison of nine automated detection schemes widely-applied in solar and space science. We study, specifically, a prevailing coronal hole observed by the Atmospheric Imaging Assembly instrument on 2018 May 30. Our results indicate that the choice of detection scheme has a significant effect on the location of the coronal hole boundary. Physical properties in coronal holes such as the area, mean intensity, and mean magnetic field strength vary by a factor of up to 4.5 between the maximum and minimum values. We conclude that our findings are relevant for coronal hole research from the past decade, and are therefore of interest to the solar and space research community. © 2021, CC BY.

关键词： Space research