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arXiv 2020年

作者： Giannakopoulos, Ilias I. Serrallés, José E.C. Daniel, Luca Sodickson, Daniel K. Polimeridis, Athanasios G. White, Jacob K. Lattanzi, Riccardo Skoltech Center for Computational Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow143026 Russia Research Laboratory of Electronics Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA United States Department of Radiology New York University School of Medicine New YorkNY United States Q Bio CA94063 United States

Objective: Global Maxwell Tomography (GMT) is a recently introduced volumetric technique for noninvasive estimation of electrical properties (EP) from magnetic resonance measurements. Previous work evaluated GMT using ideal radiofrequency (RF) excitations. The aim of this simulation study was to assess GMT performance with a realistic RF coil. Methods: We designed a transmit-receive RF coil with 8 decoupled channels for 7T head imaging. We calculated the RF transmit field (B1+) inside heterogeneous head models for different RF shimming approaches, and used them as input for GMT to reconstruct EP for all voxels. Results: Coil tuning/decoupling remained relatively stable when the coil was loaded with different head models. Mean error in EP estimation changed from 7.5% to 9.5% and from 4.8% to 7.2% for relative permittivity and conductivity, respectively, when changing head model without re-tuning the coil. Results slightly improved when an SVD-based RF shimming algorithm was applied, in place of excitation with one coil at a time. Despite errors in EP, RF transmit field (B1+) and absorbed power could be predicted with less than 0.5% error over the entire head. GMT could accurately detect a numerically inserted tumor. Conclusion: This work demonstrates that GMT can reliably reconstruct EP in realistic simulated scenarios using a tailored 8-channel RF coil design at 7T. Future work will focus on construction of the coil and optimization of GMT's robustness to noise, to enable in-vivo GMT experiments. Significance: GMT could provide accurate estimations of tissue EP, which could be used as biomarkers and could enable patient-specific estimation of RF power deposition, which is an unsolved problem for ultrahigh-field magnetic resonance imaging. Copyright © 2020, The Authors. All rights reserved.

关键词： Integral equations

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Author Correction: Employing fingerprinting of medicinal plants by means of LC-MS and machine learning for species identification task

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Scientific reports 2020年第1期10卷 11482页

作者： Pavel Kharyuk Dmitry Nazarenko Ivan Oseledets Igor Rodin Oleg Shpigun Andrey Tsitsilin Mikhail Lavrentyev Skolkovo Institute of Science and Technology Center for Computational and Data-Intensive Science and Engineering Moscow 143026 Russia. kharyuk.pavel@***. Institute of Numerical Mathematics of the Russian Academy of Sciences Moscow 119991 Russia. kharyuk.pavel@***. Lomonosov Moscow State University Faculty of Chemistry Moscow 119991 Russia. dmitro.nazarenko@***. Skolkovo Institute of Science and Technology Center for Computational and Data-Intensive Science and Engineering Moscow 143026 Russia. Institute of Numerical Mathematics of the Russian Academy of Sciences Moscow 119991 Russia. Lomonosov Moscow State University Faculty of Chemistry Moscow 119991 Russia. All-Russian Research Institute of Medicinal and Aromatic Plants (VILAR) Moscow 117216 Russia. Saratov State University Department of Botanics and Ecology Saratov 410012 Russia.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

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Quantum voting and its physical interpretation∗

arXiv

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arXiv 2019年

作者： Yoo, Woong-seon Seoul 06642 Korea Republic of Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow Russia

Voting is a game with a no-go theorem. New proofs of Arrow’s impossibility theorem are given based on quantum information theory. We show that the Arrowian dictator is equivalent to the perfect cloning circuit. We present Gedankenexperiment of voting and Bell-like inequalities of voting. We provide the thermodynamic interpretation of voting with Landauer’s principle. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum optics

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SciServer: A science platform for astronomy and beyond

arXiv

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arXiv 2020年

作者： Taghizadeh-Popp, Manuchehr Kim, Jai Won Lemson, Gerard Medvedev, Dmitry Jordan Raddick, M. Szalay, Alexander S. Thakar, Aniruddha R. Booker, Joseph Chhetri, Camy Dobos, Laszlo Rippin, Michael Institute For Data Intensive Engineering and Science Johns Hopkins University 3701 San Martin Drive BaltimoreMD21218 United States Department of Physics of Complex Systems Eotvos Lorand University Pf. 32 BudapestH-1518 Hungary

We present SciServer, a science platform built and supported by the institute for data intensive engineering and science at the Johns Hopkins University. SciServer builds upon and extends the SkyServer system of server-side tools that introduced the astronomical community to SQL (Structured Query Language) and has been serving the Sloan Digital Sky Survey catalog data to the public. SciServer uses a Docker/VM based architecture to provide interactive and batch mode server-side analysis with scripting languages like Python and R in various environments including Jupyter (notebooks), RStudio and command-line in addition to traditional SQL-based data analysis. Users have access to private file storage as well as personal SQL database space. A flexible resource access control system allows users toÂă share their resources with collaborators, a feature that has also been very useful in classroom environments. All these services, wrapped in a layer of REST APIs, constituteÂăa scalable collaborative data-driven science platform that is attractive to science disciplines beyond astronomy. Copyright © 2020, The Authors. All rights reserved.

关键词： Access control

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Discovery of Magnetospheric Interactions in the Doubly-Magnetic Hot Binary ∊ Lupi

arXiv

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arXiv 2023年

作者： Biswas, Ayan Das, Barnali Chandra, Poonam Wade, Gregg A. Shultz, Matthew E. Cavallaro, Francesco Petit, Veronique Woudt, Patrick A. Alecian, Evelyne National Centre for Radio Astrophysics Tata Institute of Fundamental Research Ganeshkhind Pune411007 India Department of Physics Engineering Physics & Astronomy Queen's University KingstonONK7L 3N6 Canada Department of Physics & Space Science Royal Military College of Canada PO Box 17000 Station Forces KingstonONK7K 0C6 Canada Department of Physics and Astronomy University of Delaware NewarkDE19716 United States National Radio Astronomy Observatory 520 Edgemont Road CharlottesvilleVA22903 United States Inter-University Institute for Data Intensive Astronomy Department of Astronomy University of Cape Town Private Bag X3 Rondebosch7701 South Africa Univ. Grenoble Alpes CNRS IPAG Grenoble38000 France

Magnetic fields are extremely rare in close, hot binaries, with only 1.5% of such systems known to contain a magnetic star. The eccentric ∊ Lupi system stands out in this population as the only close binary in which both stars are known to be magnetic. We report the discovery of strong, variable radio emission from ∊ Lupi using the upgraded Giant Metrewave Radio Telescope (uGMRT) and the MeerKAT radio telescope. The light curve exhibits striking, unique characteristics including sharp, high-amplitude pulses that repeat with the orbital period, with the brightest enhancement occurring near periastron. The characteristics of the light curve point to variable levels of magnetic reconnection throughout the orbital cycle, making ∊ Lupi the first known high-mass, main sequence binary embedded in an interacting magnetosphere. We also present a previously unreported enhancement in the X-ray light curve obtained from archival XMM-Newton data. The stability of the components' fossil magnetic fields, the firm characterization of their relatively simple configurations, and the short orbital period of the system make ∊ Lupi an ideal target to study the physics of magnetospheric interactions. This system may thus help us to illuminate the exotic plasma physics of other magnetically interacting systems such as moon-planet, planet-star, and star-star systems including T Tauri binaries, RS CVn systems, and neutron star binaries. Copyright © 2023, The Authors. All rights reserved.

关键词： Magnetic fields

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Giant Isolated Attosecond Pulses from Two-Color Laser-Plasma Interactions

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Physical Review Letters 2020年第11期124卷 114802-114802页

作者： Y. X. Zhang S. Rykovanov Mingyuan Shi C. L. Zhong X. T. He B. Qiao M. Zepf Center for Applied Physics and Technology HEDPS SKLNPT and School of Physics Peking University Beijing 100871 China Helmholtz Institute Jena 07743 Jena Germany Laser Fusion Research Center China Academy of Engineering Physics Mianyang 621900 China Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology 121205 Moscow Russia Collaborative Innovation Center of IFSA Shanghai Jiao Tong University Shanghai 200240 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Institute of Optics and Quantum Electronics Friedrich Schiller University 07743 Jena Germany

A new regime in the interaction of a two-color (ω,2ω) laser with a nanometer-scale foil is identified, resulting in the emission of extremely intense, isolated attosecond pulses—even in the case of multicycle lasers. For foils irradiated by lasers exceeding the blow-out field strength (i.e., capable of fully separating electrons from the ion background), the addition of a second harmonic field results in the stabilization of the foil up to the blow-out intensity. This is then followed by a sharp transition to transparency that essentially occurs in a single optical cycle. During the transition cycle, a dense, nanometer-scale electron bunch is accelerated to relativistic velocities and emits a single, strong attosecond pulse with a peak intensity approaching that of the laser field.

关键词： Fast particle effects in plasmas High-energy-density plasmas High-order harmonic generation Laser-plasma interactions Radiation & particle generation in plasmas Radiation pressure acceleration X-ray generation in plasmas

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Optimization-based approach to the calibration of mesoscale mechanical models for carbon nanotube systems

arXiv

引用

arXiv 2019年

作者： Petrov, Vitaly Ostanin, Igor Zhilyaev, Petr Center for Design Manufacturing and Materials Skolkovo Institute of Science and Technology Moscow Russia Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow Russia

A new mesoscale mechanical model, describing elastic interactions in carbon nanotubes (CNT) and other nanofilaments, is proposed. Functional form of the developed model is based on enhanced vector model (EVM) that describes basic types of bond deformations: tension, torsion, bending and shear. Calibration of bond stiffnesses is performed by adjusting EVM parameters to reproduce both CNT's deformation energies and shape observed in a full-atomistic simulation. The parameters obtained are compared with the ones obtained from Euler-Bernoulli beam theory considerations. It is found that after certain critical length of a tested CNT specimen its stiffness parameters become length-independent and can be used in mesoscale simulations of CNTs of arbitrary length. Copyright © 2019, The Authors. All rights reserved.

关键词： Carbon nanotubes

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DronePick: Object picking and delivery teleoperation with the drone controlled by a wearable tactile display

arXiv

引用

arXiv 2019年

作者： Ibrahimov, Roman Tsykunov, Evgeny Shirokun, Vladimir Somov, Andrey Tsetserukou, Dzmitry Intelligent Space Robotics Laboratory Skolkovo Institute of Science and Technology Moscow Russia Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow Russia

We report on the teleoperation system DronePick which provides remote object picking and delivery by a human-controlled quadcopter. The main novelty of the proposed system is that the human user continuously gets the visual and haptic feedback for accurate teleoperation. DronePick consists of a quadcopter equipped with a magnetic grabber, a tactile glove with finger motion tracking sensor, hand tracking system, and the Virtual Reality (VR) application. The human operator teleoperates the quadcopter by changing the position of the hand. The proposed vibrotactile patterns representing the location of the remote object relative to the quadcopter are delivered to the glove. It helps the operator to determine when the quadcopter is right above the object. When the "pick" command is sent by clasping the hand in the glove, the quadcopter decreases its altitude and the magnetic grabber attaches the target object. The whole scenario is in parallel simulated in VR. The air flow from the quadcopter and the relative positions of VR objects help the operator to determine the exact position of the delivered object to be picked. The experiments showed that the vibrotactile patterns were recognized by the users at the high recognition rates: the average 99% recognition rate and the average 2.36s recognition time. The real-life implementation of DronePick featuring object picking and delivering to the human was developed and tested. Copyright © 2019, The Authors. All rights reserved.

关键词： Remote control

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AA-ICP: Iterative closest point with anderson acceleration

AA-ICP: Iterative closest point with anderson acceleration

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2018 IEEE International Conference on Robotics and Automation, ICRA 2018

作者： Pavlov, Artem L. Ovchinnikov, Grigory W.V. Derbyshev, Dmitry Yu. Tsetserukou, Dzmitry Oseledets, Ivan V. Skolkovo Institute of Science and Technology Skolkovo Innovation Center Space Center Moscow143026 Russia Skolkovo Institute of Science and Technology Computational and Data-Intensive Science and Engineering Russia Moscow Institute of Physics and Technology Russia Skolkovo Institute of Science and Technology Space Center Russia Skolkovo Institute of Science and Technology Center for Computational and Data-Intensive Science and Engineering Russia

ISBN: (纸本)9781538630815

Iterative Closest Point (ICP) is a widely used method for performing scan-matching and registration. Being simple and robust, this method is still computationally expensive and may be challenging to use in real-time applications with limited resources on mobile platforms. In this paper we propose a novel effective method for acceleration of ICP which does not require substantial modifications to the existing code. This method is based on an idea of Anderson acceleration which is an iterative procedure for finding a fixed point of contractive mapping. The latter is often faster than a standard Picard iteration, usually used in ICP implementations. We show that ICP, being a fixed point problem, can be significantly accelerated by this method enhanced by heuristics to improve overall robustness. We implement proposed approach into Point Cloud Library (PCL) and make it available online. Benchmarking on the real-world data fully supports our claims. © 2018 IEEE.

关键词： Iterative methods

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Corvus A: A low-mass, isolated galaxy at 3.5 Mpc

arXiv

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arXiv 2024年

作者： Jones, Michael G. Sand, David J. Mutlu-Pakdil, Burçin Fielder, Catherine E. Crnojević, Denija Bennet, Paul Spekkens, Kristine Donnerstein, Richard Doliva-Dolinsky, Amandine Karunakaran, Ananthan Strader, Jay Zaritsky, Dennis Steward Observatory University of Arizona 933 North Cherry Avenue Rm. N204 TucsonAZ85721-0065 United States Department of Physics and Astronomy Dartmouth College HanoverNH03755 United States University of Tampa 401 West Kennedy Boulevard TampaFL33606 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Physics and Space Science Royal Military College of Canada P.O. Box 17000 Station Forces Kingston ONK7K 7B4 Canada Department of Physics Engineering Physics and Astronomy Queen’s University KingstonONK7L 3N6 Canada Department of Astronomy & Astrophysics University of Toronto TorontoONM5S 3H4 Canada Dunlap Institute for Astronomy and Astrophysics University of Toronto TorontoONM5S 3H4 Canada Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States

We report the discovery of Corvus A, a low-mass, gas-rich galaxy at a distance of approximately 3.5 Mpc, identified in DR10 of the Dark Energy Camera Legacy Imaging Survey during the initial phase of our ongoing SEmi-Automated Machine LEarning Search for Semi-resolved galaxies (SEAMLESS). Jansky Very Large Array observations of Corvus A detect H i line emission at a radial velocity of 523 ± 2 km s−1. Magellan/Megacam imaging reveals an irregular and complex stellar population with both young and old stars. We detect UV emission in Neil Gehrels Swift observations, indicative of recent star formation. However, there are no signs of H ii regions in Hα imaging from Steward Observatory’s Kuiper telescope. Based on the Megacam color magnitude diagram we measure the distance to Corvus A via the tip-of-the-red-giant-branch standard candle as 3.48 ± 0.24 Mpc. This makes Corvus A remarkably isolated, with no known galaxy within ∼1 Mpc. Based on this distance, we estimate the H i and stellar mass of Corvus A to be log MHI/M. = 6.59 and log M∗/M. = 6.0. Although there are some signs of rotation, the H i distribution of Corvus A appears to be close to face-on, analogous to that of Leo T, and we therefore do not attempt to infer a dynamical mass from its H i line width. Higher resolution synthesis imaging is required to confirm this morphology and to draw robust conclusions from its gas kinematics. © 2024, CC BY.

关键词： Galaxies

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