检索结果-内蒙古大学图书馆

The Multiband Imaging Survey for High-Alpha PlanetS (MISHAPS) I: Preliminary Constraints on the Occurrence Rate of Hot Jupiters in 47 Tucanae

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Crisp, Alison L. Klüter, Jonas Newman, Marz L. Penny, Matthew T. Beatty, Thomas G. Cleeves, L. Ilsedore Collins, Karen A. Johnson, Jennifer A. Johnson, Marshall C. Lund, Michael B. Martínez-Vázquez, Clara E. Ness, Melissa K. Rodriguez, Joseph E. Siverd, Robert Stevens, Daniel J. Villanueva, Steven Ziegler, Carl Department of Physics & Astronomy Louisiana State University Baton RougeLA70803 United States Department of Astronomy The Ohio State University ColumbusOH43210 United States Center for Computation & Technology Louisiana State University Baton RougeLA70803 United States Department of Astronomy University of Wisconsin – Madison MadisonWI53706 United States Department of Astronomy University of Virginia CharlottesvilleVA22904 United States Department of Chemistry University of Virginia CharlottesvilleVA22904 United States Harvard-Smithsonian Center for Astrophysics CambridgeMA02138 United States Center for Cosmology & Astro Particle Physics The Ohio State University ColumbusOH43210 United States NASA Exoplanet Science Institute California Institute of Technology PasadenaCA91125 United States Gemini North Observatory NOIRLab HiloHI96720 United States Department of Astronomy Columbia University New YorkNY10027 United States Simons Center for Computational Astrophysics Flatiron Institute New YorkNY10004 United States Center for Data Intensive and Time Domain Astronomy Department of Physics & Astronomy Michigan State University East LansingMI48824 United States Institute for Astronomy University of Hawai’i at Mānoa HonoluluHI96822 United States Department of Physics & Astronomy University of Minnesota – Duluth DuluthMN55812 United States Exoplanets & Stellar Astrophysics Laboratory NASA Goddard Space Flight Center GreenbeltMD20771 United States Department of Physics Engineering & Astronomy Stephen F. Austin State University NacogdochesTX75962 United States

The first generation of transiting planet searches in globular clusters yielded no detections, and in hindsight, only placed occurrence rate limits slightly higher than the measured occurrence rate in the higher-metallicity Galactic thick disk. To improve these limits, we present the first results of a new wide field search for transiting hot Jupiters in the globular cluster 47 Tucanae. We have observed 47 Tuc as part of the Multiband Imaging Survey for High-Alpha Planets (MISHAPS). Using 24 partial and full nights of observations taken with the Dark Energy Camera on the 4-m Blanco telescope at CTIO, we perform a search on 19,930 stars in the outer regions of the cluster. Though we find no clear planet detections, by combining our result with the upper limit enabled by Gilliland et al.’s (2000) Hubble search for planets around an independent sample of 34,091 stars in the inner cluster, we place the strongest limit to date on hot Jupiters with periods of 0.8 ≤ P ≤ 8.3 days and 0.5 RJup ≤ RP ≤ 2.0 RJup of fHJ © 2024, CC BY.

关键词： Stars

RadioAstron Space VLBI Imaging of the jet in M87: I. Detection of high brightness temperature at 22 GHz

学校读者我要写书评

暂无评论

arXiv 2023年

作者： Kim, Jae-Young Savolainen, Tuomas Voitsik, Petr Kravchenko, Evgeniya V. Lisakov, Mikhail M. Kovalev, Yuri Y. Müller, Hendrik Lobanov, Andrei P. Sokolovsky, Kirill V. Bruni, Gabriele Edwards, Philip G. Reynolds, Cormac Bach, Uwe Gurvits, Leonid I. Krichbaum, Thomas P. Hada, Kazuhiro Giroletti, Marcello Orienti, Monica Anderson, James M. Lee, Sang-Sung Sohn, Bong Won Zensus, J. Anton Department of Astronomy and Atmospheric Sciences Kyungpook National University Daegu702-701 Korea Republic of Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Aalto University Department of Electronics and Nanoengineering PL 15500 AaltoFI-00076 Finland Aalto University Metsähovi Radio Observatory Metsähovintie 114 KylmäläFI-02540 Finland Lebedev Physical Institute The Russian Academy of Sciences Leninsky prospekt 53 Moscow119991 Russia Moscow Institute of Physics and Technology Dolgoprudny Institutsky per. 9 Moscow141700 Russia Department of Astronomy University of Illinois at Urbana-Champaign 1002 W. Green Street UrbanaIL61801 United States Center for Data Intensive and Time Domain Astronomy Department of Physics and Astronomy Michigan State University 567 Wilson Rd East LansingMI48824 United States Sternberg Astronomical Institute Moscow State University Universitetskij pr. 13 Moscow119992 Russia INAF-Istituto di Astrofisica e Planetologia Spaziali via Fosso del Cavaliere 100 RomaI-00133 Italy CSIRO Astronomy and Space Science PO Box 76 EppingNSW1710 Australia CSIRO Astronomy and Space Science PO Box 1130 BentleyWA6102 Australia Oude Hoogeveensedijk 4 DwingelooNL-7991 PD Netherlands Faculty of Aerospace Engineering Delft University of Technology Kluyverweg 1 DelftNL-2629 HS Netherlands Mizusawa VLBI Observatory National Astronomical Observatory of Japan 2-12 Hoshigaoka Mizusawa Iwate Oshu023-0861 Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan via Gobetti 101 Bologna40129 Italy Leibniz Institute for Agricultural Engineering and Bioeconomy Max-Eyth-Allee 100 Potsdam-BornimD-14469 Germany Korea Astronomy and Space Science Institute 776 Daedeok-daero Yuseong-gu Daejeon34055 Korea Republic of

We present results from the first 22 GHz space very-long-baseline interferometric (VLBI) imaging observations of M87 by RadioAstron. As a part of the Nearby AGN Key science Program, the source was observed in Feb 2014 at 22 GHz with 21 ground stations, reaching projected (u, v)-spacings up to ∼ 11 Gλ. The imaging experiment was complemented by snapshot RadioAstron data of M87 obtained during 2013–2016 from the AGN Survey Key science Program. Their longest baselines extend up to ∼ 25 Gλ. For all these measurements, fringes are detected only up to ∼2.8 Earth Diameter or ∼3 Gλ baseline lengths, resulting in a new image with angular resolution of ∼ 150 µas or ∼ 20 Schwarzschild radii spatial resolution. The new image not only shows edge-brightened jet and counterjet structures down to submilliarcsecond scales but also clearly resolves the VLBI core region. While the overall size of the core is comparable to those reported in the literature, the ground-space fringe detection and slightly super-resolved RadioAstron image suggest the presence of substructures in the nucleus, whose minimum brightness temperature exceeds TB,min ∼ 1012 K. It is challenging to explain the origin of this record-high TB,min value for M87 by pure Doppler boosting effect with a simple conical jet geometry and known jet speed. Therefore, this can be evidence for more extreme Doppler boosting due to a blazar-like small jet viewing angle or highly efficient particle acceleration processes occurring already at the base of the outflow. © 2023, CC BY.

关键词： Luminance

Relativistic slingshot: A source for single circularly polarized attosecond x-ray pulses

学校读者我要写书评

暂无评论

Physical Review E 2020年第6期102卷 061201(R)-061201(R)页

作者： Jingwei Wang Sergei V. Bulanov Min Chen Bifeng Lei Yuxue Zhang Rishat Zagidullin Veronika Zorina Wei Yu Yuxin Leng Ruxin Li Matt Zepf Sergey G. Rykovanov State Key Laboratory of High Field Laser Physics CAS Center for Excellence in Ultra-intense Laser Science Shanghai Institute of Optics and Fine Mechanics (SIOM) Chinese Academy of Sciences (CAS) Shanghai 201800 China Collaborative Innovation Center of IFSA Shanghai Jiao Tong University Shanghai 200240 China Institute of Physics ASCR v.v.i. (FZU) ELI-Beamlines Project 182 21 Prague Czech Republic Key Laboratory for Laser Plasmas (MoE) School of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Helmholtz Institute Jena Fröbelstieg 3 07743 Jena Germany Faculty of Physics and Astronomy Friedrich-Schiller-Universität Jena 07743 Jena Germany Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Moscow 121205 Russia

We propose a mechanism to generate a single intense circularly polarized attosecond x-ray pulse from the interaction of a circularly polarized relativistic few-cycle laser pulse with an ultrathin foil at normal incidence. Analytical modeling and particle-in-cell simulation demonstrate that a huge charge-separation field can be produced when all the electrons are displaced from the target by the incident laser, resulting in a high-quality relativistic electron mirror that propagates against the tail of the laser pulse. The latter is efficiently reflected as well as compressed into an attosecond pulse that is also circularly polarized.

关键词： High intensity laser-plasma interactions X-ray generation in plasmas Relativistic plasmas Particle-in-cell methods Test-particle methods

Iterative joint image demosaicking and denoising using a residual denoising network

学校读者我要写书评

暂无评论

arXiv 2018年

作者： Kokkinos, Filippos Lefkimmiatis, Stamatios Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology

Modern digital cameras rely on the sequential execution of separate image processing steps to produce realistic images. The first two steps are usually related to denoising and demosaicking where the former aims to reduce noise from the sensor and the latter converts a series of light intensity readings to color images. Modern approaches try to jointly solve these problems, i.e. joint denoising-demosaicking which is an inherently ill-posed problem given that two-thirds of the intensity information is missing and the rest are perturbed by noise. While there are several machine learning systems that have been recently introduced to solve this problem, the majority of them relies on generic network architectures which do not explicitly take into account the physical image model. In this work we propose a novel algorithm which is inspired by powerful classical image regularization methods, large-scale optimization, and deep learning techniques. Consequently, our derived iterative optimization algorithm, which involves a trainable denoising network, has a transparent and clear interpretation compared to other black-box data driven approaches. Our extensive experimentation line demonstrates that our proposed method outperforms any previous approaches for both noisy and noisefree data across many different datasets. This improvement in reconstruction quality is attributed to the rigorous derivation of an iterative solution and the principled way we design our denoising network architecture, which as a result requires fewer trainable parameters than the current state-of-the-art solution and furthermore can be efficiently trained by using a significantly smaller number of training data than existing deep demosaicking networks. Copyright © 2018, The Authors. All rights reserved.

关键词： Network architecture

Scaling up the lattice dynamics of amorphous materials by orders of magnitude

学校读者我要写书评

暂无评论

Physical Review B 2020年第2期102卷 024108-024108页

作者： Ivan Kriuchevskyi Vladimir V. Palyulin Rico Milkus Robert M. Elder Timothy W. Sirk Alessio Zaccone Department of Physics “A. Pontremoli” University of Milan via Celoria 16 20133 Milan Italy Centre for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Nobelya Ulitsa 3 Moscow 121205 Russia Department of Chemical Engineering and Biotechnology University of Cambridge Cambridge CB3 0AS United Kingdom Polymers Branch U.S. Army Research Laboratory Aberdeen Proving Ground Maryland 20783 USA Bennett Aerospace Inc. Cary North Carolina 27518 USA Center for Devices and Radiological Health U.S. Food and Drug Administration Silver Spring Maryland 20903 USA

We generalize the nonaffine theory of viscoelasticity for use with large, well-sampled systems of arbitrary chemical complexity. Having in mind predictions of mechanical and vibrational properties of amorphous systems with atomistic resolution, we propose an extension of the kernel polynomial method (KPM) for the computation of the vibrational density of states and the eigenmodes, including the Γ correlator of the affine force field, which is a key ingredient of lattice-dynamic calculations of viscoelasticity. We show that the results converge well to the solution obtained by direct diagonalization (DD) of the Hessian (dynamical) matrix. As is well known, the DD approach has prohibitively high computational requirements for systems with N=104 atoms or larger. Instead, the KPM approach developed here allows one to scale up lattice dynamic calculations of real materials up to 106 atoms, with a hugely more favorable (linear) scaling of computation time and memory consumption with N.

关键词： Dissipative dynamics Lattice dynamics Mechanical deformation Amorphous materials Polydisperse materials Polymer glasses Random & disordered media Viscoelasticity Molecular dynamics Numerical techniques

Author Correction: Medical history predicts phenome-wide disease onset and enables the rapid response to emerging health threats

学校读者我要写书评

暂无评论

Nature communications 2025年第1期16卷 1507页

作者： Jakob Steinfeldt Benjamin Wild Thore Buergel Maik Pietzner Julius Upmeier Zu Belzen Andre Vauvelle Stefan Hegselmann Spiros Denaxas Harry Hemingway Claudia Langenberg Ulf Landmesser John Deanfield Roland Eils Department of Cardiology Angiology and Intensive Care Medicine Deutsches Herzzentrum der Charité (DHZC) Berlin Germany. Charité - Universitätsmedizin Berlin corporate member of Freie Universität Berlin and Humboldt Universität zu Berlin Klinik/Centrum Berlin Germany. Computational Medicine Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. Friede Springer Cardiovascular Prevention Center@Charite Charite - University Medicine Berlin Berlin Germany. Institute of Cardiovascular Sciences University College London London UK. Center for Digital Health Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. MRC Epidemiology Unit Institute of Metabolic Science University of Cambridge Cambridge UK. Precision Health University Research Institute Queen Mary University of London and Barts NHS Trust London UK. Institute of Health Informatics University College London London UK. Institute for Medical Engineering and Science Massachusetts Institute of Technology Massachusetts USA. Pattern Recognition and Image Analysis Lab University of Münster Münster Germany. British Heart Foundation Data Science Centre London UK. Health Data Research UK London UK. National Institute for Health Research Biomedical Research Centre at University College London Hospitals London UK. Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. DZHK (German Centre for Cardiovascular Research) Partner Site Berlin Berlin Berlin Germany. Center for Digital Health Berlin Institute of Health (BIH) Charite - University Medicine Berlin Berlin Germany. roland.eils@bih-charite.de. Health Data Science Unit Heidelberg University Hospital and BioQuant Heidelberg Germany. roland.eils@bih-charite.de.

Optimizing Laser Pulses for Narrow-Band Inverse Compton Sources in the High-Intensity Regime

学校读者我要写书评

暂无评论

Physical Review Letters 2019年第20期122卷 204802-204802页

作者： Daniel Seipt Vasily Yu. Kharin Sergey G. Rykovanov Helmholtz-Institut Jena Fröbelstieg 3 07743 Jena Germany Center for Ultrafast Optical Science University of Michigan Ann Arbor Michigan 48109 USA Research Institute Moscow R&D Lab Moscow Bersenevskaya nab. 6 119072 Russia Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Nobel Str. 3 Skolkovo Russia

Scattering of ultraintense short laser pulses off relativistic electrons allows one to generate a large number of X- or gamma-ray photons with the expense of the spectral width—temporal pulsing of the laser inevitable leads to considerable spectral broadening. In this Letter, we describe a simple method to generate optimized laser pulses that compensate the nonlinear spectrum broadening and can be thought of as a superposition of two oppositely linearly chirped pulses delayed with respect to each other. We develop a simple analytical model that allows us to predict the optimal parameters of such a two-pulse—the delay, amount of chirp, and relative phase—for generation of a narrow-band γ-ray spectrum. Our predictions are confirmed by numerical optimization and simulations including three-dimensional effects.

关键词： Gamma-ray generation in plasmas High intensity laser-plasma interactions Strong electromagnetic field effects Radiation from moving charges

Explainable AI: Definition and attributes of a good explanation for health AI

学校读者我要写书评

暂无评论

arXiv 2024年

作者： Kyrimi, Evangelia McLachlan, Scott Wohlgemut, Jared M. Perkins, Zane B. Lagnado, David A. Marsh, William Gimson, Alexander Shafti, Ali Ercole, Ari Banerjee, Amitava Glocker, Ben Schafer, Burkhard Gatsonis, Constantine Grosan, Crina Sent, Danielle Berman, David S. Glass, David O'Regan, Declan P. Letsios, Dimitrios Morrissey, Dylan Pisirir, Erhan Leofante, Francesco Soyel, Hamit Williamson, Jon Grieman, Keri Dube, Kudakwashe Mardsen, Max Nagendran, Myura Tai, Nigel Kostopoulou, Olga Jones, Owain Curzon, Paul Stoner, Rebecca S. Tandle, Sankalp Joshi, Shalmali Mossadegh, Somayyeh Buijsman, Stefan Miller, Tim Madai, Vince Istvan School of Electronic Engineering and Computer Science Queen Mary University of London London United Kingdom School of Nursing Midwifery and Palliative Care King's College London London United Kingdom Centre for Trauma Sciences Blizard Institute Queen Mary University of London London United Kingdom Royal London Hospital Barts Health NHS Trust London United Kingdom Department of Experiment Psychology University College London London United Kingdom Cambridge Liver Unit Addenbrooke's Hospital Cambridge University Hospitals Hills Road Box 210 Cambridge United Kingdom University of Cambridge United Kingdom Cambridge Consultants Ltd. United Kingdom Division of Anaesthesia Cambridge Centre for AI in Medicine University of Cambridge Cambridge United Kingdom Magdelene College University of Cambridge United Kingdom Institute of Health Informatics University College London London United Kingdom Department of Computing Imperial College London London United Kingdom SCRIPT Centre for IT and IP Law School of Law University of Edinburgh United Kingdom Center for Statistical Sciences School of Public Health Brown University Providence United States Research Group Artificial Intelligence HU University of Applied Sciences Utrecht Netherlands Jheronimus Academy of Data Science Tilburg University Eindhoven University of Technology s-Hertogenbosch Netherlands Centre for Theoretical Physics Queen Mary University of London London United Kingdom School of Computing Ulster University Belfast United Kingdom MRC Laboratory of Medical Sciences Imperial College London London United Kingdom Department of Informatics King's College London United Kingdom Physiotherapy Department Barts Health NHS Trust London United Kingdom Sport and Exercise Medicine Queen Mary University of London London United Kingdom School of Electronic Engineering and Computer Science Queen Mary University of London United Kingdom Department of Computing Imperial College London United Kingdom Departmen

Proposals of artificial intelligence (AI) solutions based on increasingly complex and accurate predictive models are becoming ubiquitous across many disciplines. As the complexity of these models grows, transparency and users' understanding often diminish. This suggests that accurate prediction alone is insufficient for making an AI-based solution truly useful. In the development of healthcare systems, this introduces new issues related to accountability and safety. Understanding how and why an AI system makes a recommendation may require complex explanations of its inner workings and reasoning processes. Although research on explainable AI (XAI) has significantly increased in recent years and there is high demand for XAI in medicine, defining what constitutes a good explanation remains ad hoc, and providing adequate explanations continues to be challenging. To fully realize the potential of AI, it is critical to address two fundamental questions about explanations for safety-critical AI applications, such as health-AI: (1) What is an explanation in health-AI? and (2) What are the attributes of a good explanation in health-AI? In this study, we examined published literature and gathered expert opinions through a two-round Delphi study. The research outputs include (1) a definition of what constitutes an explanation in health-AI and (2) a comprehensive list of attributes that characterize a good explanation in health-AI. © 2024, CC BY.

关键词：

Optimizing Laser Pulses for Narrowband Inverse Compton Sources in the High-Intensity Regime

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Seipt, Daniel Yu. Kharin, Vasily Rykovanov, Sergey G. Helmholtz-Institut Jena Fröbelstieg 3 Jena07743 Germany Center for Ultrafast Optical Science University of Michigan Ann Arbor MI48109 United States Center for Computational and Data-Intensive Science and Engineering Skolkovo Institute of Science and Technology Nobel Str. 3 Skolkovo Russia

Scattering of ultraintense short laser pulses off relativistic electrons allows one to generate a large number of X- or gamma-ray photons with the expense of the spectral width—temporal pulsing of the laser inevitable leads to considerable spectral broadening. In this Letter, we describe a simple method to generate optimized laser pulses that compensate the nonlinear spectrum broadening, and can be thought of as a superposition of two oppositely linearly chirped pulses delayed with respect to each other. We develop a simple analytical model that allow us to predict the optimal parameters of such a two-pulse—the delay, amount of chirp and relative phase—for generation of a narrowband γ-ray spectrum. Our predictions are confirmed by numerical optimization and simulations including 3D effects. Copyright © 2019, The Authors. All rights reserved.

关键词： Gamma rays