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Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived from First-Year Fermi Large Area Telescope data

Physical Review Letters 2010年第10期104卷 101101-101101页

作者： A. A. Abdo M. Ackermann M. Ajello W. B. Atwood L. Baldini J. Ballet G. Barbiellini D. Bastieri B. M. Baughman K. Bechtol R. Bellazzini B. Berenji R. D. Blandford E. D. Bloom E. Bonamente A. W. Borgland J. Bregeon A. Brez M. Brigida P. Bruel T. H. Burnett S. Buson G. A. Caliandro R. A. Cameron P. A. Caraveo J. M. Casandjian E. Cavazzuti C. Cecchi Ö. Çelik E. Charles A. Chekhtman C. C. Cheung J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi L. R. Cominsky J. Conrad S. Cutini C. D. Dermer A. de Angelis F. de Palma S. W. Digel G. Di Bernardo E. do Couto e Silva P. S. Drell A. Drlica-Wagner R. Dubois D. Dumora C. Farnier C. Favuzzi S. J. Fegan W. B. Focke P. Fortin M. Frailis Y. Fukazawa S. Funk P. Fusco D. Gaggero F. Gargano D. Gasparrini N. Gehrels S. Germani B. Giebels N. Giglietto P. Giommi F. Giordano T. Glanzman G. Godfrey I. A. Grenier M.-H. Grondin J. E. Grove L. Guillemot S. Guiriec M. Gustafsson Y. Hanabata A. K. Harding M. Hayashida R. E. Hughes R. Itoh M. S. Jackson G. Jóhannesson A. S. Johnson R. P. Johnson T. J. Johnson W. N. Johnson T. Kamae H. Katagiri J. Kataoka N. Kawai M. Kerr J. Knödlseder M. L. Kocian F. Kuehn M. Kuss J. Lande L. Latronico M. Lemoine-Goumard F. Longo F. Loparco B. Lott M. N. Lovellette P. Lubrano G. M. Madejski A. Makeev M. N. Mazziotta W. McConville J. E. McEnery C. Meurer P. F. Michelson W. Mitthumsiri T. Mizuno A. A. Moiseev C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia P. L. Nolan J. P. Norris E. Nuss T. Ohsugi N. Omodei E. Orlando J. F. Ormes D. Paneque J. H. Panetta D. Parent V. Pelassa M. Pepe M. Pesce-Rollins F. Piron T. A. Porter S. Rainò R. Rando M. Razzano A. Reimer O. Reimer T. Reposeur S. Ritz L. S. Rochester A. Y. Rodriguez M. Roth F. Ryde H. F.-W. Sadrozinski D. Sanchez A. Sander P. M. Saz Parkinson J. D. Scargle A. Sellerholm C. Sgrò M. S. Shaw E. J. Siskind D. A. Smith P. D. Smith G. Spandre P. Spinelli J.-L. Starck M. S. Strickman A. W. Strong D. J. Suson H. Tajima H. Takahashi T. Takahashi T. Tanaka J. B. Thayer J. G. Thayer D. J. Thompson L. Tibald Space Science Division Naval Research Laboratory Washington D.C. 20375 USA National Research Council Research Associate National Academy of Sciences Washington D.C. 20001 USA 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 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 Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Laboratoire AIM CEA-IRFU/CNRS/Université Paris Diderot Service d’Astrophysique CEA Saclay 91191 Gif sur Yvette France Istituto Nazionale di Fisica Nucleare Sezione di Trieste I-34127 Trieste Italy Dipartimento di Fisica Università di Trieste I-34127 Trieste Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica “G. Galilei ” Università di Padova I-35131 Padova Italy Department of Physics Center for Cosmology and Astro-Particle Physics The Ohio State University Columbus Ohio 43210 USA Istituto Nazionale di Fisica Nucleare Sezione di Perugia I-06123 Perugia Italy Dipartimento di Fisica Università degli Studi di Perugia I-06123 Perugia 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 70126 Bari Italy Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 Palaiseau France Department of Physics University of Washington Seattle Washington 98195-1560 USA Institut de Ciencies de l’Espai (IEEC-CSIC) Campus UAB 08193 Barcelona Spain INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy Agenzia Spaziale Italiana (ASI) Science Data Center I-00044 Frascati (Roma) Italy NASA Goddard Space Flight Center Greenbelt Maryland 20771 USA Center for Res

We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called “extragalactic” diffuse γ-ray emission (EGB). This component of the diffuse γ-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic γ-ray emission, the detected LAT sources, and the solar γ-ray emission. We find the spectrum of the EGB is consistent with a power law with a differential spectral index γ=2.41±0.05 and intensity I(>100 MeV)=(1.03±0.17)×10−5 cm−2 s−1 sr−1, where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.

关键词： Gamma rays

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Fermi Large Area Telescope Search for Photon Lines from 30 to 200 GeV and Dark Matter Implications

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Physical Review Letters 2010年第9期104卷 091302-091302页

作者： A. A. Abdo M. Ackermann M. Ajello W. B. Atwood L. Baldini J. Ballet G. Barbiellini D. Bastieri K. Bechtol R. Bellazzini B. Berenji E. D. Bloom E. Bonamente A. W. Borgland A. Bouvier J. Bregeon A. Brez M. Brigida P. Bruel T. H. Burnett S. Buson G. A. Caliandro R. A. Cameron P. A. Caraveo S. Carrigan J. M. Casandjian C. Cecchi Ö. Çelik A. Chekhtman J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi J. Conrad C. D. Dermer A. de Angelis F. de Palma S. W. Digel E. do Couto e Silva P. S. Drell A. Drlica-Wagner R. Dubois D. Dumora Y. Edmonds R. Essig C. Farnier C. Favuzzi S. J. Fegan W. B. Focke P. Fortin M. Frailis Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Gehrels S. Germani N. Giglietto F. Giordano T. Glanzman G. Godfrey I. A. Grenier J. E. Grove L. Guillemot S. Guiriec M. Gustafsson D. Hadasch A. K. Harding D. Horan R. E. Hughes M. S. Jackson G. Jóhannesson A. S. Johnson R. P. Johnson W. N. Johnson T. Kamae H. Katagiri J. Kataoka N. Kawai M. Kerr J. Knödlseder M. Kuss J. Lande L. Latronico M. Llena Garde F. Longo F. Loparco B. Lott M. N. Lovellette P. Lubrano A. Makeev M. N. Mazziotta J. E. McEnery C. Meurer P. F. Michelson W. Mitthumsiri T. Mizuno A. A. Moiseev C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia P. L. Nolan J. P. Norris E. Nuss T. Ohsugi N. Omodei E. Orlando J. F. Ormes M. Ozaki D. Paneque J. H. Panetta D. Parent V. Pelassa M. Pepe M. Pesce-Rollins F. Piron S. Rainò R. Rando M. Razzano A. Reimer O. Reimer T. Reposeur J. Ripken S. Ritz A. Y. Rodriguez M. Roth H. F.-W. Sadrozinski A. Sander P. M. Saz Parkinson J. D. Scargle T. L. Schalk A. Sellerholm C. Sgrò E. J. Siskind D. A. Smith P. D. Smith G. Spandre P. Spinelli J.-L. Starck M. S. Strickman D. J. Suson H. Tajima H. Takahashi T. Tanaka J. B. Thayer J. G. Thayer L. Tibaldo D. F. Torres Y. Uchiyama T. L. Usher V. Vasileiou N. Vilchez V. Vitale A. P. Waite P. Wang B. L. Winer K. S. Wood T. Ylinen M. Ziegler Space Science Division Naval Research Laboratory Washington D.C. 20375 USA National Research Council Research Associate National Academy of Sciences Washington D.C. 20001 USA 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 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 Istituto Nazionale di Fisica Nucleare Sezione di Pisa I-56127 Pisa Italy Laboratoire AIM CEA-IRFU/CNRS/Université Paris Diderot Service d’Astrophysique CEA Saclay 91191 Gif sur Yvette France Istituto Nazionale di Fisica Nucleare Sezione di Trieste I-34127 Trieste Italy Dipartimento di Fisica Università di Trieste I-34127 Trieste Italy Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica “G. Galilei” Università di Padova I-35131 Padova Italy Istituto Nazionale di Fisica Nucleare Sezione di Perugia I-06123 Perugia Italy Dipartimento di Fisica Università degli Studi di Perugia I-06123 Perugia 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 70126 Bari Italy Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 Palaiseau France USA Department of Physics University of Washington Seattle Washington 98195-1560 USA Institut de Ciencies de l’Espai (IEEC-CSIC) Campus UAB 08193 Barcelona Spain INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy NASA Goddard Space Flight Center Greenbelt Maryland 20771 USA Center for Research and Exploration in Space Science and Technology (CRESST) and NASA Goddard Space Flight Center Greenbelt Maryland 20771 USA Department of Physics and Center for Space Sciences and Technology Uni

Dark matter (DM) particle annihilation or decay can produce monochromatic γ rays readily distinguishable from astrophysical sources. γ-ray line limits from 30 to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20–300 GeV are presented using a selection based on requirements for a γ-ray line analysis, and integrated over most of the sky. We obtain γ-ray line flux upper limits in the range 0.6–4.5×10−9 cm−2 s−1, and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.

关键词： Gamma rays

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Semantic Technologies in System Maintenance (STSM 2008)

Semantic Technologies in System Maintenance (STSM 2008)

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IEEE Workshop on Program Comprehension

作者： Juergen Rilling René Witte Dragan Gaševic Jeff Z. Pan Department of Computer Science and Software Engineering Concordia University Montréal Québec Canada University of Karlsruhe Institute for Program Structures and Data Organization (IPD) Karlsruhe Germany Department of Computing Science Aberdeen The University of Aberdeen Scotland UK

This paper gives a brief overview of the international workshop on semantic technologies in system maintenance. It describes a number of semantic technologies (e.g., ontologies, text mining, and knowledge integration techniques) and identifies diverse tasks in software maintenance where the use of semantic technologies can be beneficial, such as traceability, system comprehension, software artifact analysis, and information integration.

关键词： Ontologies Software maintenance Space technology Application software Semantic Web Logic programming Computer science OWL Software engineering Information systems

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Grid enabled simultaneous retrieval of aerosol and ground surface reflectance from integration of aeronet and satellite data

Grid enabled simultaneous retrieval of aerosol and ground su...

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2008 IEEE International Geoscience and Remote Sensing Symposium - Proceedings

作者： Wan, Wei Yong, Xue Jie, Guang Linyan, Bai Ying, Wang Ai, Jianwen Li, Yinjie State Key Laboratory of Remote Sensing Science Beijing Normal University Chinese Academy of Sciences P.O. Box 9718 Beijing 100101 China Department of Computing London Metropolitan University 166-220 Holloway Road London N7 8DB United Kingdom China Center for Resource Satellite Data and Application Beijing 100830 China Graduate School of the Chinese Academy of Sciences Beijing China

ISBN: (纸本)9781424428083

In this paper, a method using multi-resource remotely sensed data and ground base data for quantitative determination of aerosol optical properties was demonstrated. The model exploits the synergy of TERRA and AQUA MODerate resolution Imaging Spectrometer (MODIS) data, to simultaneously retrieve both Aerosol Optical Thickness (AOT) and surface reflectance. The ground station data routinely coming from AERosol Robotic NETwork (AERONET) of ground-based sun- and sky-scanning radiometers were assimilated as variables describing model initial states. To meet the increased computational needs caused by the complex and computational intensity, the algorithm was migrated to run as parallel processing on a Grid platform. Experimental results were presented with a realistic pplication, using data collected by MODIS over China mainland. The results show that Grid-enabled model allowed on-demand large volume of ground-based data assimilation with parameters, and achieved improvement both in retrieval accuracy and computing performance. © 2008 IEEE.

关键词： Optical properties

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Using a high throughput computational grid for the retrieval of aerosol properties over China land 21

Using a high throughput computational grid for the retrieval...

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21st Congress of the International Society for Photogrammetry and Remote Sensing, ISPRS 2008

作者： Wan, Wei Xue, Yong Bai, Linyan Guang, Jie Li, Yinjie Ai, Jianwen Wang, Ying State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications Chinese Academy of Sciences and Beijing Normal University Institute of Remote Sensing Applications Chinese Academy of Sciences P.O. Box 9718 Beijing100101 China Graduate School of the Chinese Academy of Sciences Beijing China Department of Computing London Metropolitan University 166-220 Holloway Road LondonN78 DB United Kingdom China Center for Resource Satellite Data and Applications Beijing100073 China

This paper describes the need for and the proposed designing of the high performance quantitative retrieval model to be used on Computational Grid for study of aerosol properties, with particular emphasis on Aerosol Optical Thickness (AOT) determination. A methodology using multi-resource remotely sensed data and adapting available aerosol retrieval model in a Grid environment is demonstrated. The algorithm comprises two complementary parts, collectively used in a distributed application. This paper focused on parallelization method based on a resource management and task partition strategy. A module, called DPPA (Dynamic Partition Points Algorithm for workload estimation), is designed as a portable technology for developing and deploying Grid execution in a generic data parallel paradigm. Experimental results are presented in a realistic application, using data collected by MODIS over China land. Derived result and computing performance of the proposed algorithm is given using the Grid test-bed at the Institute of Remote Sensing Applications of Chinese Academy of sciences (IRSA, CAS). Combined, the experimental results show that Grid-enabled model allowed on-demand large volume of ground-based data assimilation with parameters, and achieved substantial reductions in computational times. The research gives a thoughtful perspective on the potential of applying high performance computing practices to remote sensing quantitative retrieving problems.

关键词： Optical remote sensing

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A peer-to-peer indexing service for data grids

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2nd International Conference on Grid and Pervasive computing

作者： Jensen, Henrik Thostrup Kleist, Josva Department of Computer Science Aalborg University Danish Center for Grid Computing Nordic Data Grid Facility

ISBN: (纸本)9783540723592

We present an index system for locating files or other data objects in a grid environment. The system is constructed using a distributed hash table, and is scalable, fault-tolerant, and self-organizing. The index is dynamically updated to reflect the state of the storage elements, and can hence deal with nomadic data. The system provides extra services to ease integration with other systems: A registrant service integrates existing storage elements into the system, and a query proxy provides an easy way to query the system. A security model, which builds on the existing grid security model is also provided. An implementation has been created and its performance measured. The system is shown to scale as more nodes are added to the system.

关键词： Grid computing

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Feature Identification and Extraction in Function Fields

Feature Identification and Extraction in Function Fields

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9th Joint Eurographics/IEEE VGTC Symposium on Visualization, EuroVis 2007

作者： Anderson, John C. Gosink, Luke J. Duchaineau, Mark A. Joy, Kenneth I. Institute for Data Analysis and Visualization Department of Computer Science University of California Davis United States Center for Applied Scientific Computing Lawrence Livermore National Laboratory

ISBN: (纸本)9783905673456

We present interactive techniques for identifying and extracting features in function fields. Function fields map points in n-dimensional Euclidean space to 1-dimensional scalar functions. Visual feature identification is accomplished by interactively rendering scalar distance fields, constructed by applying a function-space distance metric over the function field. Combining visual exploration with feature extraction queries, formulated as a set of function-space constraints, facilitates quantitative analysis and annotation. Numerous application domains give rise to function fields. We present results for two-dimensional hyperspectral images, and a simulated time-varying, three-dimensional air quality dataset. © The Eurographics Association 2007.

关键词： Air quality

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Digital preservation of interactive multimedia performances

Digital preservation of interactive multimedia performances

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International Computer Music Conference, ICMC 2007

作者： Ng, Kia Pham, Tran Vu Ong, Bee Barthélemy, Jérôme Bonardi, Alain Giaretta, David ICSRiM University of Leeds School of Computing LeedsLS2 9JT United Kingdom IRCAM 1 place Igor-Stravinksy Paris75004 France STFC Rutherford Appleton Laboratory Space Data Space Science and Technology Department OxfordshireOX11 0QX United Kingdom

Interactive multimedia technologies and digital media are now usual tools and resources for contemporary performing arts. From the perspective of recreating a performance and/or later analysis, these technologies and media have added much complexity to preservation issues. Preserving an interactive multimedia performance involves keeping human interactions with multimedia systems, the multimedia contents generated (usually music and graphical animation) and the artistic, cultural and technical knowledge embedded in the performance material so that a recreation of the performance is possible in the future. This paper introduces an approach to such a challenging preservation by using 3D motion data for coding human interactions and ontologies for knowledge preservation together with the preservation framework developed in the CASPAR EC IST project, which is based on the standardised Open Archival Information System (OAIS) reference model. The work reported is part of the contemporary arts testbed of CASPAR.

关键词： Digital storage

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Routing characteristics of ad hoc networks with unidirectional links

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Ad Hoc Networks 2006年第3期4卷 303-325页

作者： Jetcheva, Jorjeta G. Johnson, David B. Computer Science Department Carnegie Mellon University Pittsburgh PA 15213 United States Computer Science Department Rice University Houston TX 77005 United States Firetide Inc. ACM SIGMOBILE Sigma Xi Phi Beta Kappa Rice University Special Interest Group on Mobility of Systems Users Data and Computing ACM IEEE IEEE Computer Society IEEE Communications Society USENIX

Unidirectional links in an ad hoc network can result from factors such as heterogeneity of receiver and transmitter hardware, power control or topology control algorithms, or differing sources of interference or jamming. Previously proposed metrics for evaluating the difficulty of a unidirectional scenario are limited in scope and are frequently misleading. To be able to analyze ad hoc network routing protocol behavior in a complex networking environment, it is not sufficient to merely assign a single level of difficulty to a unidirectional network scenario;the many interrelated routing characteristics of these scenarios must be understood. In this paper, we develop a set of metrics for describing these characteristics, for example for characterizing routing scenarios in simulations, analysis, and testbed implementations. Based on these metrics, we perform a detailed simulation analysis of the routing characteristics of the three most common simulation models for generating unidirectional links in ad hoc networks: the random-power model, the two-power model, and the three-power model. Our findings enable protocol designers to better choose a set of network scenarios and parameters that truly explore a wide range of a routing protocol's behaviors in the presence of unidirectional links, and to better understand the complex interplay between routing mechanisms and network conditions. © 2004 Elsevier B.V. All rights reserved.

关键词： Telecommunication networks

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Cluster computing and Grid 2005 works in progress

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IEEE Distributed Systems Online 2005年第9期6卷 2页

作者： Wang, Frank Helian, Na Wu, Sining Deng, Yuhui Zhou, Ke Guo, Yike Thompson, Steve Johnson, Ian Milward, Dave Maddock, Robert Khoo, Benjamin Bharadwaj, Veeravalli Cambridge-Cranfield High Performance Computing Facility London Metropolitan University Cranfield University Imperial College Xyratex Department of Grid Computing and E-science Centre for Grid Computing Data Mining at the London Metropolitan University Centre for Grid Computing Cranfield University London E-science Centre Parallel Computing Centre Imperial College National University of Singapore Department of Electrical and Computer Engineering National University of Singapore

A grid-oriented storage (GOS) project, which aims to support advanced data bank services and data reservoirs for sharing data on the gird, is discussed. The GOS appliance is a disk array that connects directly to the grid using a Globus XIO interface and fits in the thin server categorization. The security model of the GOS is based on the Grid security Infrastructure (GSI). A dynamic estimation scheme for fault-free scheduling in grid systems is also discussed. Most of the grid falls into one of the two categories, planned and negotiated, and dynamic and voluntary. This discrepancy is the main reason behind the complexity in designing robust and fault tolerant scheduling algorithms for both resource categories.

关键词： data storage equipment

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