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arXiv 2018年

作者： Ackermann, M. Atwood, W.B. Baldini, L. Ballet, J. Barbiellini, G. Bastieri, D. Bellazzini, R. Berenji, B. Bissaldi, E. Blandford, R.D. Bloom, E.D. Bonino, R. Bottacini, E. Bregeon, J. Bruel, P. Buehler, R. Cameron, R.A. Caputo, R. Caraveo, P.A. Cavazzuti, E. Charles, E. Chekhtman, A. Cheung, C.C. Chiaro, G. Ciprini, S. Cohen-Tanugi, J. Conrad, J. Costantin, D. D’Ammando, F. de Palma, F. Digel, S.W. Di Lalla, N. Di Mauro, M. Di Venere, L. Favuzzi, C. Fegan, S.J. Focke, W.B. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gargano, F. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guillemot, L. Guiriec, S. Horan, D. Jóhannesson, G. Johnson, C. Kensei, S. Kocevski, D. Kuss, M. Larsson, S. Latronico, L. Li, J. Longo, F. Loparco, F. Lovellette, M.N. Lubrano, P. Magill, J.D. Maldera, S. Malyshev, D. Manfreda, A. Mazziotta, M.N. McEnery, J.E. Meyer, M. Michelson, P.F. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Moretti, E. Morselli, A. Moskalenko, I.V. Negro, M. Nuss, E. Ojha, R. Omodei, N. Orienti, M. Orlando, E. Ormes, J.F. Palatiello, M. Paliya, V.S. Paneque, D. Persic, M. Pesce-Rollins, M. Piron, F. Principe, G. Rainò, S. Rando, R. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Ritz, S. Sánchez-Conde, M. Sgrò, C. Siskind, E.J. Spada, F. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Thayer, J.G. Thayer, J.B. Torres, D.F. Tosti, G. Troja, E. Valverde, J. Vianello, G. Wood, K. Wood, M. Zaharijas, G. Deutsches Elektronen Synchrotron DESY ZeuthenD-15738 Germany Santa Cruz Institute for Particle Physics Department of Physics Department of Astronomy and Astrophysics University of California at Santa Cruz Santa CruzCA95064 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Laboratoire AIM CEA-IRFU CNRS Université Paris Diderot Service d’Astrophysique CEA Saclay Gif sur YvetteF-91191 France Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy California State University Los Angeles Department of Physics and Astronomy Los AngelesCA90032 United States Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 MontpellierF-34095 France Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 PalaiseauF-91128 France NASA Goddard Space Flight Center GreenbeltMD20771 United States INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Italian Space Agency Via del Politecnico snc Roma00133 Italy College of Science George Mason University Fairfax Naval Researc

Black holes with masses below approximately 1015 g are expected to emit gamma rays with energies above a few tens of MeV, which can be detected by the Fermi Large Area Telescope (LAT). Although black holes with these masses cannot be formed as a result of stellar evolution, they may have formed in the early Universe and are therefore called Primordial Black Holes (PBHs). Previous searches for PBHs have focused on either short timescale bursts or the contribution of PBHs to the isotropic gamma-ray emission. We show that, in case of individual PBHs, the Fermi LAT is most sensitive to PBHs with temperatures above approximately 16 GeV and masses 6×1011 g, which it can detect out to a distance of about 0.03 pc. These PBHs have a remaining lifetime of months to years at the start of the Fermi mission. They would appear as potentially moving point sources with gamma-ray emission that becomes spectrally harder and brighter with time until the PBH completely evaporates. In this paper, we develop a new algorithm to detect the proper motion of a gamma-ray point sources, and apply it to 318 unassociated point sources at high galactic latitude in the third Fermi-LAT source catalog (3FGL). None of unassociated point sources with spectra consistent with PBH evaporation show significant proper motion. Using the non-detection of PBH candidates, we derive a 99% confidence limit on PBH evaporation rate in the vicinity of the Earth ρPBH 3 pc−3yr−1. This limit is similar to the limits obtained with ground-based gamma-ray observatories. Copyright © 2018, The Authors. All rights reserved.

关键词： Gamma rays

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bandicoot: a python toolbox for mobile phone metadata

The Journal of Machine Learning Research

引用

The Journal of Machine Learning Research 2016年第1期17卷

作者： Kevin Murphy Bernhard Schölkopf Yves-Alexandre De Montjoye Luc Rocher Alex Sandy Pentland Google MPI for Intelligent Systems MIT Media Lab. Cambridge MA and Imperial College London Dept. of Computing and Data Science Institute London UK Université catholique de Louvain ICTEAM Louvain-la-Neuve Belgium MIT Media Lab. Cambridge Cambridge MA

bandicoot is an open-source Python toolbox to extract more than 1442 features from standard mobile phone metadata. bandicoot makes it easy for machine learning researchers and practitioners to load mobile phone data, to analyze and visualize them, and to extract robust features which can be used for various classification and clustering tasks. Emphasis is put on ease of use, consistency, and documentation. bandicoot has no dependencies and is distributed under MIT license.

关键词： CDR feature engineering mobile phone metadata python visualization

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Characterizing Multi-media Retrieval Applications

Characterizing Multi-media Retrieval Applications

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International Conference on Parallel Processing (ICPP)

作者： Yunping Lu Xin Wang Weihua Zhang Yi Li Wenyun Zhao Shanghai Key Laboratory of Data Science Fudan University Shanghai China State Key Lab of Mathematical Engineering and Advanced Computing Wuxi China Software School Fudan University Shanghai China Parallel Processing Institute Fudan University Shanghai China

Multimedia data, especially image and video data, have become one of the most overwhelming data types on the Internet recently. Considering the user experience and real application requirements, multimedia data always demand a real-time processing speed. As a result, the huge amount of such data make retrieving useful information from them not only data-intensive, but also computation-intensive, which poses significant challenges to current system and architecture designs. Unfortunately, most prior studies focus only on text based retrieval systems or traditional multimedia processing applications. As far as we know, there is no systematic study on analyzing the characteristics of multimedia retrieval applications and how they might impact system and architecture designs. In this paper, we make the first attempt to construct a multimedia retrieval benchmark suite (called MMR Bench) to evaluate the corresponding system and architecture designs. To embody diverse multimedia retrieval applications, we collect eight state-of-the-art multimedia retrieval algorithms which cover the whole retrieval stages, including feature extraction, feature matching, and spatial verification. To satisfy diverse evaluation purposes, we implement multiple versions for each algorithm, including sequential version, pthread version for multi-core evaluation and data-parallel (i.e., Map-reduce) version for data-center evaluation. Moreover, MMR Bench provides flexible interfaces through retrieval stages, as well as a tool to adjust parameters and regenerating different scales of reasonable input. With such a flexible design, the algorithms in MMR Bench may be not only suitable for individual kernel-level evaluation, but also capable to be integrated into a complete infrastructure for system-level evaluation. Based on MMR Bench, we further analyze the inherent architectural characteristics, such as input size sensitivity and workload balance, which provides some insights into system and archite

关键词： Multimedia communication Feature extraction Benchmark testing Streaming media Algorithm design and analysis Computer architecture

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Search for Cosmic-Ray Electron and Positron Anisotropies with Seven Years of Fermi Large Area Telescope data

引用

Physical Review Letters 2017年第9期118卷 091103-091103页

作者： S. Abdollahi M. Ackermann M. Ajello A. Albert W. B. Atwood L. Baldini G. Barbiellini R. Bellazzini E. Bissaldi E. D. Bloom R. Bonino E. Bottacini T. J. Brandt P. Bruel S. Buson M. Caragiulo E. Cavazzuti A. Chekhtman S. Ciprini F. Costanza A. Cuoco S. Cutini F. D’Ammando F. de Palma R. Desiante S. W. Digel N. Di Lalla M. Di Mauro L. Di Venere B. Donaggio P. S. Drell C. Favuzzi W. B. Focke Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Giglietto F. Giordano M. Giroletti D. Green S. Guiriec A. K. Harding T. Jogler G. Jóhannesson T. Kamae M. Kuss S. Larsson L. Latronico J. Li F. Longo F. Loparco P. Lubrano J. D. Magill D. Malyshev A. Manfreda M. N. Mazziotta M. Meehan P. F. Michelson W. Mitthumsiri T. Mizuno A. A. Moiseev M. E. Monzani A. Morselli M. Negro E. Nuss T. Ohsugi N. Omodei D. Paneque J. S. Perkins M. Pesce-Rollins F. Piron G. Pivato G. Principe S. Rainò R. Rando M. Razzano A. Reimer O. Reimer C. Sgrò D. Simone E. J. Siskind F. Spada G. Spandre P. Spinelli A. W. Strong H. Tajima J. B. Thayer D. F. Torres E. Troja J. Vandenbroucke G. Zaharijas S. Zimmer Department of Physical Sciences Hiroshima University Higashi-Hiroshima Hiroshima 739-8526 Japan Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany Department of Physics and Astronomy Clemson University Kinard Lab of Physics Clemson South Carolina 29634-0978 USA Los Alamos National Laboratory Los Alamos New Mexico 87545 USA Santa Cruz Institute for Particle Physics Department of Physics and Department of Astronomy and Astrophysics University of California at Santa Cruz Santa Cruz California 95064 USA Dipartimento di Fisica “Enrico Fermi” dell’Università di Pisa I-56126 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Istituto Nazionale di Fisica Nucleare Sezione di Trieste I-34127 Trieste Italy Dipartimento di Fisica Università di Trieste I-34127 Trieste Italy Dipartimento di Fisica “M. Merlin” dell’Università e del Politecnico di Bari I-70126 Bari Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari I-70126 Bari Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics and SLAC National Accelerator Laboratory Stanford University Stanford California 94305 USA Istituto Nazionale di Fisica Nucleare Sezione di Torino I-10125 Torino Italy Dipartimento di Fisica Università degli Studi di Torino I-10125 Torino Italy NASA Goddard Space Flight Center Greenbelt Maryland 20771 USA Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 F-91128 Palaiseau France Agenzia Spaziale Italiana (ASI) Science Data Center I-00133 Roma Italy College of Science George Mason University Fairfax Virginia 22030 USA resident at Naval Research Laboratory Washington DC 20375 USA Istituto Nazionale di Fisica Nucleare Sezione di Perugia I-06123 Perugia Italy Institute for Theoretical Particle Physics and Cosmology (TTK) RWTH Aachen University D-52056 Aachen Germany INAF Istituto di Radioastronomia I-40129 Bologna Italy Dipartimento di Astronomia Un

The Large Area Telescope on board the Fermi Gamma-ray Space Telescope has collected the largest ever sample of high-energy cosmic-ray electron and positron events since the beginning of its operation. Potential anisotropies in the arrival directions of cosmic-ray electrons or positrons could be a signature of the presence of nearby sources. We use almost seven years of data with energies above 42 GeV processed with the Pass 8 reconstruction. The present data sample can probe dipole anisotropies down to a level of 10−3. We take into account systematic effects that could mimic true anisotropies at this level. We present a detailed study of the event selection optimization of the cosmic-ray electrons and positrons to be used for anisotropy searches. Since no significant anisotropies have been detected on any angular scale, we present upper limits on the dipole anisotropy. The present constraints are among the strongest to date probing the presence of nearby young and middle-aged sources.

关键词： Cosmic ray & astroparticle detectors Cosmic ray propagation Cosmic ray sources Cosmological parameters

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Cover Image, Volume 84, Issue 7

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Proteins: Structure, Function, and Bioinformatics 2016年第7期84卷

作者： Wei Wang Juan Liu Lin Sun Department of Computer Science and Technology College of Computer and Information Engineering Henan Normal University Xinxiang 453007 China Laboratory of Computation Intelligence and Information Processing Engineering Technology Research Center for Computing Intelligence and Data Mining Henan Province China Institute of Computer Software School of Computer Wuhan University Wuhan 430072 China

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Multivariate spearman's ρ for aggregating ranks using copulas

The Journal of Machine Learning Research

引用

The Journal of Machine Learning Research 2016年第1期17卷

作者： Kevin Murphy Bernhard Schölkopf Justin Bedö Cheng Soon Ong Google MPI for Intelligent Systems The Walter and Eliza Hall Institute Victoria Australia and The Department of Computing and Information Systems The University of Melbourne VIC Australia Data61 CSIRO Canberra ACT Australia and Research School of Computer Science The Australian National University Australia and The Department of Electrical and Electronic Engineering The University of Melbourne VIC Australia

We study the problem of rank aggregation: given a set of ranked lists, we want to form a consensus ranking. Furthermore, we consider the case of extreme lists: i.e., only the rank of the best or worst elements are known. We impute missing ranks and generalise Spearman's ρ to extreme ranks. Our main contribution is the derivation of a non-parametric estimator for rank aggregation based on multivariate extensions of Spearman's ρ, which measures correlation between a set of ranked lists. Multivariate Spearman's ρ is defined using copulas, and we show that the geometric mean of normalised ranks maximises multivariate correlation. Motivated by this, we propose a weighted geometric mean approach for learning to rank which has a closed form least squares solution. When only the best (top-k) or worst (bottom-k) elements of a ranked list are known, we impute the missing ranks by the average value, allowing us to apply Spearman's ρ. We discuss an optimistic and pessimistic imputation of missing values, which respectively maximise and minimise correlation, and show its effect on aggregating university rankings. Finally, we demonstrate good performance on the rank aggregation benchmarks MQ2007 and MQ2008.

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Personalized Financial News Recommendation Algorithm Based on Ontology

引用

Procedia Computer science 2015年 55卷 843-851页

作者： Rui Ren Lingling Zhang Limeng Cui Bo Deng Yong Shi School of Management University of Chinese Academy of Sciences Beijing 100190 China Key Laboratory of Big Data Mining and Knowledge Management Chinese Academy of Sciences Beijing 100190 China Research Centre on Fictitious Economy and Data Science Chinese Academy of Sciences Beijing 100190 China School of Computer and Control Engineering University of Chinese Academy of Sciences Beijing 100190 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China

To deal with the challenge of information overload, in this paper, we propose a financial news recommendation algorithm which help users find the articles that are interesting to read. To settle the ambiguity problem, a new presented OF-IDF method is employed to represent the unstructured text data in the form of key concepts, synonyms and synsets which are all stored in the domain ontology. For users, the recommendation algorithm build the profiles based on their behaviors to detect the genuine interests and predict current interests automatically and in real time by applying the thinking of relevance feedback. Finally, the experiment conducted on a financial news dataset demonstrates that the proposed algorithm significantly outperforms the performance of a traditional recommender.

关键词： news recommendation algorithm ontology relevence feedback OF-IDF

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Unresolved gamma-ray sky through its angular power spectrum

arXiv

引用

arXiv 2018年

作者： Ackermann, M. Ajello, M. Baldini, L. Ballet, J. Barbiellini, G. Bastieri, D. Bellazzini, R. Bissaldi, E. Blandford, R.D. Bonino, R. Bottacini, E. Bregeon, J. Bruel, P. Buehler, R. Burns, E. Buson, S. Cameron, R.A. Caputo, R. Caraveo, P.A. Cavazzuti, E. Chen, S. Chiaro, G. Ciprini, S. Costantin, D. Cuoco, A. Cutini, S. D’Ammando, F. de la Torre Luque, P. de Palma, F. Desai, A. Digel, S.W. Di Lalla, N. Di Mauro, M. Di Venere, L. Fana Dirirsa, F. Favuzzi, C. Franckowiak, A. Fukazawa, Y. Funk, S. Fusco, P. Gargano, F. Gasparrini, D. Giglietto, N. Giordano, F. Giroletti, M. Green, D. Grenier, I.A. Guillemot, L. Guiriec, S. Horan, D. Jóhannesson, G. Kuss, M. Larsson, S. Latronico, L. Li, J. Liodakis, I. Longo, F. Loparco, F. Lubrano, P. Magill, J.D. Maldera, S. Malyshev, D. Manfreda, A. Mazziotta, M.N. Mereu, I. Michelson, P.F. Mitthumsiri, W. Mizuno, T. Monzani, M.E. Morselli, A. Moskalenko, I.V. Negro, M. Nuss, E. Orienti, M. Orlando, E. Palatiello, M. Paliya, V.S. Paneque, D. Persic, M. Pesce-Rollins, M. Petrosian, V. Piron, F. Porter, T.A. Principe, G. Rainò, S. Rando, R. Razzano, M. Razzaque, S. Reimer, A. Reimer, O. Serini, D. Sgrò, C. Siskind, E.J. Spandre, G. Spinelli, P. Suson, D.J. Tajima, H. Takahashi, M. Thayer, J.B. Tibaldo, L. Torres, D.F. Troja, E. Venters, T.M. Vianello, G. Wood, K. Yassine, M. Zaharijas, G. Ammazzalorso, S. Fornengo, N. Regis, M. Deutsches Elektronen Synchrotron DESY ZeuthenD-15738 Germany Department of Physics and Astronomy Clemson University Kinard Lab of Physics ClemsonSC29634-0978 United States Università di Pisa Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Laboratoire AIM CEA-IRFU CNRS Université Paris Diderot Service d’Astrophysique CEA Saclay Gif sur YvetteF-91191 France Istituto Nazionale di Fisica Nucleare Sezione di Trieste TriesteI-34127 Italy Dipartimento di Fisica Università di Trieste TriesteI-34127 Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova PadovaI-35131 Italy Dipartimento di Fisica e Astronomia "G. Galilei" Università di Padova PadovaI-35131 Italy Istituto Nazionale di Fisica Nucleare Sezione di Pisa PisaI-56127 Italy Dipartimento di Fisica "M. Merlin" dell’Università e del Politecnico di Bari BariI-70126 Italy Istituto Nazionale di Fisica Nucleare Sezione di Bari BariI-70126 Italy W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Istituto Nazionale di Fisica Nucleare Sezione di Torino TorinoI-10125 Italy Dipartimento di Fisica Università degli Studi di Torino TorinoI-10125 Italy Department of Physics and Astronomy University of Padova Vicolo Osservatorio 3 PadovaI-35122 Italy Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 MontpellierF-34095 France Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 PalaiseauF-91128 France NASA Goddard Space Flight Center GreenbeltMD20771 United States NASA Postdoctoral Program Fellow United States NASA Goddard Space Flight Center GreenbeltMD20771 United States INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica Milano via E. Bassini 15 MilanoI-20133 Italy Italian Space Agency Via del Politecnico snc Roma00133 Italy Space Science Data Center -

The gamma-ray sky has been observed with unprecedented accuracy in the last decade by the Fermi large area telescope (LAT), allowing us to resolve and understand the high-energy Universe. The nature of the remaining unresolved emission (unresolved gamma-ray background, UGRB) below the LAT source detection threshold can be uncovered by characterizing the amplitude and angular scale of the UGRB fluctuation field. This work presents a measurement of the UGRB autocorrelation angular power spectrum based on eight years of Fermi LAT Pass 8 data products. The analysis is designed to be robust against contamination from resolved sources and noise systematics. The sensitivity to subthreshold sources is greatly enhanced with respect to previous measurements. We find evidence (with ∼ 3.7σ significance) that the scenario in which two classes of sources contribute to the UGRB signal is favored over a single class. A double power law with exponential cutoff can explain the anisotropy energy spectrum well, with photon indices of the two populations being 2.55 ± 0.23 and 1.86 ± 0.15. Copyright © 2018, The Authors. All rights reserved.

关键词： Gamma rays

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Single-dish and VLBI observations of Cygnus X-3 during the 2016 giant flare episode

arXiv

引用

arXiv 2017年

作者： Egron, E. Pellizzoni, A. Giroletti, M. Righini, S. Stagni, M. Orlati, A. Migoni, C. Melis, A. Concu, R. Barbas, L. Buttaccio, S. Cassaro, P. de Vicente, P. Nski, M.P. Gawro Lindqvist, M. Maccaferri, G. Stanghellini, C. Wolak, P. Yang, J. Navarrini, A. Loru, S. Pilia, M. Bachetti, M. Iacolina, M.N. Buttu, M. Corbel, S. Rodriguez, J. Markoff, S. Wilms, J. Pottschmidt, K. Bel, M. Cadolle Kalemci, E. Belloni, T. Grinberg, V. Marongiu, M. Vargiu, G.P. Trois, A. INAF Osservatorio Astronomico di Cagliari Via della Scienza 5 Selargius09047 Italy INAF Istituto di Radio Astronomia di Bologna Via P. Gobetti 101 Bologna40129 Italy Spain INAF Istituto di Radioastronomia Sezione di Noto Contrada Renna Bassa Noto96017 Italy Torú n Centre for Astronomy N. Copernicus University Gagarina 11 Torú n87-100 Poland Department of Earth and Space Sciences Chalmers University of Technology Onsala Space Observatory Onsala439 92 Sweden Agenzia Spaziale Italiana Via del Politecnico snc Roma00133 Italy Laboratoire AIM UMR 7158 CEA/CNRS Université Paris Diderot CEA DRF/IRFU/DAp Gif-sur-Yvette91191 France Station de Radioastronomie de Nançay Observatoire de Paris PSL Research University CNRS Univ. Orléans Nançay18330 France Anton Pannekoek Institute for Astronomy University of Amsterdam PO Box 94249 Amsterdam1090 GE Netherlands Friedrich Alexander Universität Erlangen-Nürnberg Sternwartstr. 7 Bamberg96049 Germany CRESST and NASA Goddard Space Flight Center Astrophysics Science Division Code 661 GreenbeltMD20771 United States Center for Space Science and Technology University of Maryland Baltimore County 1000 Hilltop Circle BaltimoreMD21250 United States Max Planck Computing and Data Facility Garching85748 Germany Faculty of Engineering and Natural Sciences Sabancı University Orhanlı -Tuzla Istanbul34956 Turkey INAF Osservatorio Astronomico di Brera via E. Bianchi 46 Merate23807 Italy ESA/ESTEC Keplerlaan 1 Noordwijk2201 AZ Netherlands Department of Physics and Earth Sciences University of Ferrara via Saragat 1 Ferrara44122 Italy

In September 2016, the microquasar Cygnus X-3 underwent a giant radio flare, which was monitored for 6 days with the Medicina Radio Astronomical Station and the Sardinia Radio Telescope. Long observations were performed in order to follow the evolution of the flare on a hourly scale, covering six frequency ranges from 1.5 GHz to 25.6 GHz. The radio emission reached a maximum of 13.2 ± 0.7 Jy at 7.2 GHz and 10±1 Jy at 18.6 GHz. Rapid flux variations were observed at high radio frequencies at the peak of the flare, together with rapid evolution of the spectral index: α steepened from 0.3 to 0.6 (with Sν ∝ ν−α) within 5 hours. This is the first time that such fast variations are observed, giving support to the evolution from optically thick to optically thin plasmons in expansion moving outward from the core. Based on the Italian network (Noto, Medicina and SRT) and extended to the European antennas (Torun, Yebes, Onsala), VLBI observations were triggered at 22 GHz on five different occasions, four times prior to the giant flare, and once during its decay phase. Flux variations of 2-hour duration were recorded during the first session. They correspond to a mini-flare that occurred close to the core ten days before the onset of the giant flare. From the latest VLBI observation we infer that four days after the flare peak the jet emission was extended over 30 mas. Copyright © 2017, The Authors. All rights reserved.

关键词： Stars

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Extended HMM and Ranking models for Chinese Spelling Correction 3

Extended HMM and Ranking models for Chinese Spelling Correct...

引用

3rd CIPS-SIGHAN Joint Conference on Chinese Language Processing, CLP 2014

作者： Xiong, Jinhua Zhao, Qiao Hou, Jianpeng Wang, Qianbo Wang, Yuanzhuo Cheng, Xueqi Cas Key Laboratory of Network Data Science and Technology Institute of Computing Technology University of Chinese Academy of Sciences Chinese Academy of Sciences China

Spelling correction has been studied for many decades, which can be classified into two categories: (1) regular text spelling correction, (2) query spelling correction. Although the two tasks share many common techniques, they have different concerns. This paper presents our work on the CLP-2014 bake-off. The task focuses on spelling checking on foreigner Chinese essays. Compared to online search query spelling checking task, more complicated techniques can be applied for better performance. Therefore, we proposed a unified framework for Chinese essays spelling correction based on extended HMM and ranker-based models, together with a rule-based model for further polishing. Our system showed better performance on the test dataset. © 2014 CLP 2014 - 3rd CIPS-SIGHAN Joint Conference on Chinese Language Processing. All rights reserved.

关键词： Statistical tests

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