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Fermi LAT search for dark matter in gamma-ray lines and the inclusive photon spectrum

Physical Review D 2012年第2期86卷 022002-022002页

作者： M. Ackermann M. Ajello A. Albert L. Baldini G. Barbiellini K. Bechtol R. Bellazzini B. Berenji R. D. Blandford E. D. Bloom E. Bonamente A. W. Borgland M. Brigida R. Buehler S. Buson G. A. Caliandro R. A. Cameron P. A. Caraveo J. M. Casandjian C. Cecchi E. Charles A. Chekhtman J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi J. Conrad F. D’Ammando F. de Palma C. D. Dermer E. do Couto e Silva P. S. Drell A. Drlica-Wagner Y. Edmonds R. Essig C. Favuzzi S. J. Fegan W. B. Focke Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini S. Germani N. Giglietto F. Giordano M. Giroletti T. Glanzman G. Godfrey I. A. Grenier S. Guiriec M. Gustafsson D. Hadasch M. Hayashida D. Horan R. E. Hughes T. Kamae J. Knödlseder M. Kuss J. Lande A. M. Lionetto M. Llena Garde F. Longo F. Loparco M. N. Lovellette P. Lubrano M. N. Mazziotta P. F. Michelson W. Mitthumsiri T. Mizuno A. A. Moiseev C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia M. Naumann-Godo J. P. Norris E. Nuss T. Ohsugi A. Okumura E. Orlando J. F. Ormes D. Paneque J. H. Panetta M. Pesce-Rollins F. Piron G. Pivato T. A. Porter D. Prokhorov S. Rainò R. Rando M. Razzano O. Reimer M. Roth C. Sbarra J. D. Scargle C. Sgrò E. J. Siskind A. Snyder P. Spinelli D. J. Suson H. Takahashi T. Tanaka J. G. Thayer J. B. Thayer L. Tibaldo M. Tinivella D. F. Torres G. Tosti E. Troja J. Vandenbroucke V. Vasileiou G. Vianello V. Vitale A. P. Waite B. L. Winer K. S. Wood Z. Yang S. Zimmer Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany 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 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 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 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 Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica “G. Galilei” Università di Padova I-35131 Padova Italy Institut de Ciències de l’Espai (IEEE-CSIC) Campus UAB 08193 Barcelona Spain INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy Laboratoire AIM CEA-IRFU/CNRS/Université Paris Diderot Service d’Astrophysique CEA Saclay 91191 Gif sur Yvette France Artep Inc. 2922 Excelsior Springs Court Ellicott City Maryland 21042 USAresident at Naval Research Laboratory Washington D.C. 20375 USA ASI Science Data Center I-00044 Frascati (Roma) Italy Laboratoire Univers et Particules de Montpellier Université Montpellier 2 CNRS/IN2P3 Montpellier France Department of Physics Stockholm University AlbaNova SE-106 91 Stockholm Sweden The Oskar Klein Centre for Cosmoparticle Physics AlbaNova SE-106 91 Stockholm Sweden IASF Palermo 90146 Palermo Italy INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-00133 Roma Italy Space Science Division Naval Research Labor

Dark matter particle annihilation or decay can produce monochromatic gamma-ray lines and contribute to the diffuse gamma-ray background. Flux upper limits are presented for gamma-ray spectral lines from 7 to 200 GeV and for the diffuse gamma-ray background from 4.8 GeV to 264 GeV obtained from two years of Fermi Large Area Telescope data integrated over most of the sky. We give cross-section upper limits and decay lifetime lower limits for dark matter models that produce gamma-ray lines or contribute to the diffuse spectrum, including models proposed as explanations of the PAMELA and Fermi cosmic-ray data.

关键词： FERMI surfaces DARK matter (Astronomy) ANNIHILATION reactions RADIOACTIVE decay GAMMA ray spectrometry CROSS sections (Nuclear physics)

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Anisotropies in the diffuse gamma-ray background measured by the Fermi LAT

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Physical Review D 2012年第8期85卷 083007-083007页

作者： M. Ackermann M. Ajello A. Albert L. Baldini J. Ballet G. Barbiellini D. Bastieri K. Bechtol R. Bellazzini E. D. Bloom E. Bonamente A. W. Borgland T. J. Brandt J. Bregeon M. Brigida P. Bruel R. Buehler S. Buson G. A. Caliandro R. A. Cameron P. A. Caraveo C. Cecchi E. Charles A. Chekhtman J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi J. Conrad A. Cuoco S. Cutini F. D’Ammando F. de Palma C. D. Dermer S. W. Digel E. do Couto e Silva P. S. Drell A. Drlica-Wagner R. Dubois C. Favuzzi S. J. Fegan E. C. Ferrara P. Fortin Y. Fukazawa P. Fusco F. Gargano D. Gasparrini S. Germani N. Giglietto M. Giroletti T. Glanzman G. Godfrey G. A. Gomez-Vargas T. Grégoire I. A. Grenier J. E. Grove S. Guiriec M. Gustafsson D. Hadasch M. Hayashida K. Hayashi X. Hou R. E. Hughes G. Jóhannesson A. S. Johnson T. Kamae J. Knödlseder M. Kuss J. Lande L. Latronico M. Lemoine-Goumard T. Linden A. M. Lionetto M. Llena Garde F. Longo F. Loparco M. N. Lovellette P. Lubrano M. N. Mazziotta J. E. McEnery W. Mitthumsiri T. Mizuno C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia M. Naumann-Godo J. P. Norris E. Nuss T. Ohsugi A. Okumura M. Orienti E. Orlando J. F. Ormes D. Paneque J. H. Panetta D. Parent V. Pavlidou M. Pesce-Rollins M. Pierbattista F. Piron G. Pivato S. Rainò R. Rando A. Reimer O. Reimer M. Roth C. Sbarra J. Schmitt C. Sgrò J. Siegal-Gaskins E. J. Siskind G. Spandre P. Spinelli A. W. Strong D. J. Suson H. Takahashi T. Tanaka J. B. Thayer L. Tibaldo M. Tinivella D. F. Torres G. Tosti E. Troja T. L. Usher J. Vandenbroucke V. Vasileiou G. Vianello V. Vitale A. P. Waite B. L. Winer K. S. Wood M. Wood Z. Yang S. Zimmer E. Komatsu Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany 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 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 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 CNRS IRAP F-31028 Toulouse cedex 4 France GAHEC Université de Toulouse UPS-OMP IRAP Toulouse France 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 Institut de Ciències de l’Espai (IEEE-CSIC) Campus UAB 08193 Barcelona Spain INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy Space Science Division Naval Research Laboratory Washington D.C. 20375 USA and George Mason University Fairfax Virginia 22030 USA ASI Science Data Center I-00044 Frascati (Roma) Italy Laboratoire Univers et Particules de Montpellier Université Montpellier 2 CNRS/IN2P3 Montpellier France Department of Physics Stockholm University AlbaNova SE-106 91 Stockholm Sweden The Oskar Klein Centre for Cosmoparticle Physics AlbaNova

The contribution of unresolved sources to the diffuse gamma-ray background could induce anisotropies in this emission on small angular scales. We analyze the angular power spectrum of the diffuse emission measured by the Fermi Large Area Telescope at Galactic latitudes |b|>30° in four energy bins spanning 1–50 GeV. At multipoles ℓ≥155, corresponding to angular scales ≲2°, angular power above the photon noise level is detected at >99.99% confidence level in the 1–2 GeV, 2–5 GeV, and 5–10 GeV energy bins, and at >99% confidence level at 10–50 GeV. Within each energy bin the measured angular power takes approximately the same value at all multipoles ℓ≥155, suggesting that it originates from the contribution of one or more unclustered source populations. The amplitude of the angular power normalized to the mean intensity in each energy bin is consistent with a constant value at all energies, CP/⟨I⟩2=9.05±0.84×10−6 sr, while the energy dependence of CP is consistent with the anisotropy arising from one or more source populations with power-law photon spectra with spectral index Γs=2.40±0.07. We discuss the implications of the measured angular power for gamma-ray source populations that may provide a contribution to the diffuse gamma-ray background.

关键词： GAMMA rays ANISOTROPY DIFFUSION FERMI surfaces TELESCOPES PHOTONS NUCLEAR energy

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FlashCoop: A Locality-Aware Cooperative Buffer Management for SSD-Based Storage Cluster

FlashCoop: A Locality-Aware Cooperative Buffer Management fo...

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International Conference on Parallel Processing (ICPP)

作者： Qingsong Wei Bozhao Gong Suraj Pathak Y. C. Tay Data Storage Institute Agency for Science Technology and Research Singapore School of Computing National University of Singapore Singapore

Random writes significantly limit the application of flash-based Solid State Drive (SSD) in enterprise environment due to its poor latency, negative impact on SSD lifetime and high garbage collection overhead. To release above limitations, we propose a locality-aware cooperative buffer scheme referred to as FlashCoop (Flash Cooperation), which leverages free memory of neighboring storage server to buffer writes over high speed network. Both temporal and sequential localities of access pattern are exploited in the design of cooperative buffer management. Leveraging the filtering effect of the cooperative buffer, FlashCoop can efficiently shape the I/O request stream and improve the sequentiality of the write accesses passed to the SSD. FlashCoop has been extensively evaluated under various enterprise workloads. Our benchmark results conclusively demonstrate that FlashCoop can achieve 52.3% performance improvement and 56.5% garbage collection overhead reduction compared to the system without FlashCoop.

关键词： Servers Buffer storage Flash memory Resource management Writing Dynamic scheduling Bandwidth

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Knowledge extraction from multiple criteria linear programming classification approach

Knowledge extraction from multiple criteria linear programmi...

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作者： Zhang, Yuejin Zhang, Peng Zhang, Lingling Shi, Yong Research Center on Fictitious Economy and Data Sciences Chinese Academy of Sciences 100190 Beijing China School of Management Graduate University of Chinese Academy of Sciences 100190 Beijing China Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China College of Information Science and Technology University of Nebraska Ant Omaha NE68182 Omaha United States

As an effective model for classification, Multiple Criteria Linear Programming (MCLP) has been widely used in business intelligence. However, a possible limitation of MCLP is that it generates unexplainable black-box models which can only tell us results without reasons. To overcome this shortage, in this paper, we present a knowledge mining strategy which mines explainable decision rules from black-box MCLP models. Firstly, we use the rough set theory to distinguish the definable set where samples are perfectly classified, from the rough set where misclassified samples may exist. Then, to get explainable knowledge, we present a clustering-based decision rule extraction approach to extract knowledge from the definable set, and a rough set-based rule extraction approach to the rough set. Finally, empirical studies on real world VIP Email data sets demonstrate that our method can effectively extract explicit rules from MCLP model with only a little lost in performance.

关键词： Linear programming

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ERRATUM: 'FERMI DETECTION OF γ-RAY EMISSION FROM THE M2 SOFT X-RAY FLARE ON 2010 JUNE 12' (2012, ApJ, 745, 144)

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The Astrophysical Journal 2012年第2期748卷

作者： M. Ackermann M. Ajello A. Allafort W. B. Atwood L. Baldini G. Barbiellini D. Bastieri K. Bechtol R. Bellazzini P. N. Bhat R. D. Blandford E. Bonamente A. W. Borgland J. Bregeon M. S. Briggs M. Brigida P. Bruel R. Buehler J. M. Burgess S. Buson G. A. Caliandro R. A. Cameron J. M. Casandjian C. Cecchi E. Charles A. Chekhtman J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi V. Connaughton J. Conrad S. Cutini B. R. Dennis F. de Palma C. D. Dermer S. W. Digel E. do Couto e Silva P. S. Drell A. Drlica-Wagner R. Dubois C. Favuzzi S. J. Fegan E. C. Ferrara P. Fortin Y. Fukazawa P. Fusco F. Gargano S. Germani N. Giglietto F. Giordano M. Giroletti T. Glanzman G. Godfrey L. Grillo J. E. Grove D. Gruber S. Guiriec D. Hadasch M. Hayashida E. Hays D. Horan G. Iafrate G. Jóhannesson A. S. Johnson W. N. Johnson T. Kamae R. M. Kippen J. Knödlseder M. Kuss J. Lande L. Latronico F. Longo F. Loparco B. Lott M. N. Lovellette P. Lubrano M. N. Mazziotta J. E. McEnery C. Meegan J. Mehault P. F. Michelson W. Mitthumsiri C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia R. Murphy M. Naumann-Godo E. Nuss T. Nymark M. Ohno T. Ohsugi A. Okumura N. Omodei E. Orlando W. S. Paciesas J. H. Panetta D. Parent M. Pesce-Rollins V. Petrosian M. Pierbattista F. Piron G. Pivato H. Poon T. A. Porter R. Preece S. Rainò R. Rando M. Razzano S. Razzaque A. Reimer O. Reimer S. Ritz C. Sbarra R. A. Schwartz C. Sgrò G. H. Share E. J. Siskind P. Spinelli H. Takahashi T. Tanaka Y. Tanaka J. B. Thayer L. Tibaldo M. Tinivella A. K. Tolbert G. Tosti E. Troja Y. Uchiyama T. L. Usher J. Vandenbroucke V. Vasileiou G. Vianello V. Vitale A. vonKienlin A. P. Waite C. Wilson-Hodge D. L. Wood K. S. Wood Z. Yang Deutsches Elektronen Synchrotron DESY D-15738 Zeuthen Germany W. W. Hansen Experimental Physics Laboratory Kavli Institute for Particle Astrophysics and Cosmology Department of Physics and SLAC National Accelerator Laboratory Stanford University Stanford CA 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 CA 95064 USA 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 Istituto Nazionale di Fisica Nucleare Sezione di Padova I-35131 Padova Italy Dipartimento di Fisica 'G. Galilei ' Università di Padova I-35131 Padova Italy Center for Space Plasma and Aeronomic Research (CSPAR) University of Alabama in Huntsville Huntsville AL 35899 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 I-70126 Bari Italy Laboratoire Leprince-Ringuet École polytechnique CNRS/IN2P3 Palaiseau France Institut de Ciències de l'Espai (IEEE-CSIC) Campus UAB E-08193 Barcelona Spain Laboratoire AIM CEA-IRFU/CNRS/Université Paris Diderot Service d'Astrophysique CEA Saclay 91191 Gif sur Yvette France Artep Inc. 2922 Excelsior Springs Court Ellicott City MD 21042 USA Resident at Naval Research Laboratory Washington DC 20375 USA. ASI Science Data Center I-00044 Frascati (Roma) Italy Laboratoire Univers et Particules de Montpellier Université Montpellier 2 CNRS/IN2P3 Montpellier France Department of Physics Stockholm University AlbaNova SE-106 91 Stockholm Sweden The Oskar Klein Centre for Cosmoparticle Physics AlbaNova SE-106 91 Stockhol

Due to an error at the publisher, the times given for the major tick marks in the X-axis in Figure 1 of the published article are incorrect. The correctly labeled times should be '00:52:00,' '00:54:00,'..., and '01:04:00.' The correct version of Figure 1 and its caption is shown below. IOP Publishing sincerely regrets this error.

关键词： acceleration of particles Sun: flares Sun: particle emission Sun: X-rays, gamma rays

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Knowledge extraction from multiple criteria linear programming classification approach

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Procedia Computer science 2010年第1期1卷 2441-2448页

作者： Yuejin Zhang Peng Zhang Lingling Zhang Yong Shi Research Center on Fictitious Economy and Data Sciences Chinese Academy of Sciences 100190 Beijing China School of Management Graduate University of Chinese Academy of Sciences 100190 Beijing China Institute of Computing Technology Chinese Academy of Sciences Beijing 100190 China College of Information Science and Technology University of Nebraska ant Omaha NE68182 Omaha USA

关键词： MCLP Rule extraction Clustering Rough set

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Reports of the AAAI 2010 conference workshops

Reports of the AAAI 2010 conference workshops

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作者： Aha, David W. Boddy, Mark Bulitko, Vadim D'Avila Garcez, Artur S. Doshi, Prashant Edelkamp, Stefan Geib, Christopher Gmytrasiewicz, Piotr Goldman, Robert P. Halevy, Alon Hitzler, Pascal Isbell, Charles Josyula, Darsana Kaelbling, Leslie Pack Kersting, Kristian Kunda, Maithilee Lamb, Luis C. Marthi, Bhaskara McGreggor, Keith Mihalkova, Lilyana Nastase, Vivi Natarajan, Sriraam Provan, Gregory Raja, Anita Ram, Ashwin Riedl, Mark Russell, Stuart Sabharwal, Ashish Smaus, Jan-Georg Sukthankar, Gita Tuyls, Karl Van Der Meyden, Ron Adaptive Systems Section Naval Research Laboratory Washington DC United States Adventium Labs. Minneapolis MN United States Department of Computer Science University of Alberta Canada City University London United Kingdom University of Georgia United States University of Bremen Germany School of Informatics University of Edinburgh United Kingdom University of Illinois Chicago United States Smart Information Flow Technologies LLC Minneapolis MN United States Structured Data Group Google Research United States Department of Computer Science Wright State University Dayton OH United States School of Interactive Computing Georgia Institute of Technology Atlanta GA United States Department of Computer Science Bowie State University United States Department of Computer Science and Engineering Massachusetts Institute of Technology United States Statistical Relational Mining Group Fraunhofer IAIS Germany Department of Computer Science Federal University of Rio Grande Do sul Brazil Willow Garage Inc. CA United States Computer Science Department University of Maryland College Park United States Heidelberg Institute for Theoretical Studies Heidelberg Germany Department of Computer Science University of Wisconsin Madison United States University College Cork Ireland Cork Complex Systems Lab. Ireland Department of Software and Information Systems University of North Carolina Charlotte United States Department of Computer Science and Engineering University of California Berkeley United States Department of Computer Science Cornell University United States Institute for Computational Sustainability United States University of Freiburg Germany School of Electrical Engineering and Computer Science University of Central Florida United States Maastricht University Netherlands University of New South Wales NICTA Australia

The AAAI-10 workshop program was held on July 11-12, 2010, at the Westin Peachtree Plaza in Atlanta, Georgia. The workshop program included 13 workshops covering a wide range of topics in artificial intelligence. There were several presentations on particular formalisms for combining the levels of planning from the perspectives of classical planning, motion planning, POMDPs, search-based planning, and temporal logic-based constraints. Henry Lieberman from Massachusetts institute of Technology Media Laboratory presented work developing a platform for knowledge acquisition and usage from expert users, built upon experience with eliciting information from nonexperts in a collaborative manner. The objective of the AAAI Workshop on Goal-Directed Autonomy (GDA) was to encourage discussion and novel contributions on intelligent agents that can self-select their goals. Jeremy Baxter from QinetiQ focused on user interaction, while Nick Hawes described a goal-directed reasoning framework for controlling a mobile robot.

关键词： Motion planning

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Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope

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Physical Review Letters 2011年第24期107卷 241302-241302页

作者： M. Ackermann M. Ajello A. Albert W. B. Atwood L. Baldini J. Ballet G. Barbiellini D. Bastieri K. Bechtol R. Bellazzini B. Berenji R. D. Blandford E. D. Bloom E. Bonamente A. W. Borgland J. Bregeon M. Brigida P. Bruel R. Buehler T. H. Burnett S. Buson G. A. Caliandro R. A. Cameron B. Cañadas P. A. Caraveo J. M. Casandjian C. Cecchi E. Charles A. Chekhtman J. Chiang S. Ciprini R. Claus J. Cohen-Tanugi J. Conrad S. Cutini A. de Angelis F. de Palma C. D. Dermer S. W. Digel E. do Couto e Silva P. S. Drell A. Drlica-Wagner L. Falletti C. Favuzzi S. J. Fegan E. C. Ferrara Y. Fukazawa S. Funk P. Fusco F. Gargano D. Gasparrini N. Gehrels S. Germani N. Giglietto F. Giordano M. Giroletti T. Glanzman G. Godfrey I. A. Grenier S. Guiriec M. Gustafsson D. Hadasch M. Hayashida E. Hays R. E. Hughes T. E. Jeltema G. Jóhannesson R. P. Johnson A. S. Johnson T. Kamae H. Katagiri J. Kataoka J. Knödlseder M. Kuss J. Lande L. Latronico A. M. Lionetto M. Llena Garde F. Longo F. Loparco B. Lott M. N. Lovellette P. Lubrano G. M. Madejski M. N. Mazziotta J. E. McEnery J. Mehault P. F. Michelson W. Mitthumsiri T. Mizuno C. Monte M. E. Monzani A. Morselli I. V. Moskalenko S. Murgia M. Naumann-Godo J. P. Norris E. Nuss T. Ohsugi A. Okumura N. Omodei E. Orlando J. F. Ormes M. Ozaki D. Paneque D. Parent M. Pesce-Rollins M. Pierbattista F. Piron G. Pivato T. A. Porter S. Profumo S. Rainò M. Razzano A. Reimer O. Reimer S. Ritz M. Roth H. F.-W. Sadrozinski C. Sbarra J. D. Scargle T. L. Schalk C. Sgrò E. J. Siskind G. Spandre P. Spinelli L. Strigari D. J. Suson H. Tajima H. Takahashi T. Tanaka J. G. Thayer J. B. Thayer D. J. Thompson L. Tibaldo M. Tinivella D. F. Torres E. Troja Y. Uchiyama J. Vandenbroucke V. Vasileiou G. Vianello V. Vitale A. P. Waite P. Wang B. L. Winer K. S. Wood M. Wood Z. Yang S. Zimmer M. Kaplinghat G. D. Martinez 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 Department of Physics Center for Cosmology and Astro-Particle Physics The Ohio State University Columbus Ohio 43210 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 Department of Physics University of Washington Seattle Washington 98195-1560 USA Institut de Ciències de l’Espai (IEEE-CSIC) Campus UAB 08193 Barcelona Spain Istituto Nazionale di Fisica Nucleare Sezione di Roma “Tor Vergata” I-00133 Roma Italy Dipartimento di Fisica Università di Roma “Tor Vergata” I-00133 Roma Italy INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica I-20133 Milano Italy Artep Inc. 2922 Excelsior Springs Court Ellicott City Maryland 21042 USA ASI Science Data Center I-00044 Frascati (Roma) Italy Laboratoire Univers et Particules de Montpell

Satellite galaxies of the Milky Way are among the most promising targets for dark matter searches in gamma rays. We present a search for dark matter consisting of weakly interacting massive particles, applying a joint likelihood analysis to 10 satellite galaxies with 24 months of data of the Fermi Large Area Telescope. No dark matter signal is detected. Including the uncertainty in the dark matter distribution, robust upper limits are placed on dark matter annihilation cross sections. The 95% confidence level upper limits range from about 10−26 cm3 s−1 at 5 GeV to about 5×10−23 cm3 s−1 at 1 TeV, depending on the dark matter annihilation final state. For the first time, using gamma rays, we are able to rule out models with the most generic cross section (∼3×10−26 cm3 s−1 for a purely s-wave cross section), without assuming additional boost factors.

关键词： MILKY Way ARTIFICIAL satellites DARK matter (Astronomy) GAMMA rays TELESCOPES

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Mining recent approximate frequent items in wireless sensor networks

Mining recent approximate frequent items in wireless sensor ...

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6th International Conference on Fuzzy Systems and Knowledge Discovery, FSKD 2009

作者： Ren, Meirui Guo, Longjiang School of Computer Science and Technology Heilongjiang University Harbin China Data Base and Parallel Computing Key Laboratory of Heilongjiang Province China School of Computer Science and Technology Harbin Institute of Technology China

ISBN: (纸本)9780769537351

Mining Frequent Items from sensory data is a major research problem in wireless sensor networks(WSNs) and it can be widely used in environmental monitoring. Conventional Lossy Counting algorithm can be applied to solve this problem in centralized manner. However, centralized algorithm brings severely data collision in WSNs, and results in inaccurate mining results. In this paper, we present D-FIMA, a distributed frequent items mining algorithm. D-FIMA, running at every sensor node, establishes items aggregation tree via forwarding mining request beforehand, and each node maintains local approximate frequent items. The root of the aggregation tree outputs the final global approximate frequent items. Theoretical analysis and the simulation results show that energy consumption of D-FIMA is much less than the centralized algorithm, and mining results of D-FIMA is more accurate than the centralized algorithm. © 2009 IEEE.

关键词： Sensor nodes

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Exact step-coupling theory for mode-coupling behavior in geometrical variation photonic crystal waveguides

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Physical Review B 2009年第3期80卷 035101-035101页

作者： E. H. Khoo A. Q. Liu X. M. Zhang E. P. Li J. Li D. Pinjala B. S. Luk’yanchuk School of Electrical and Electronic Engineering Nanyang Technological University Nanyang Avenue Singapore 639798 Singapore Institute of High Performance Computing 1 Fusionopolis Way Connexis Singapore 138632 Singapore Institute of Microelectronics 11 Science Park Road Singapore 117685 Singapore Data Storage Institute DSI Building 5 Engineering Drive 1 Singapore 117608 Singapore

In this paper, an exact step-coupling theory is developed to describe the modes coupling behavior and lightwaves propagation for the power exchange between the waveguide modes in geometrical variation photonic crystal waveguide. The exact step-coupling theory provides a general description of the mode-coupling mechanism for light waveguide with geometrical variation with complete set of equations and solutions. The coupling equations of the exact step theory are derived and compared with the scattering matrix method, where simulation results show good agreement with an error of less than 2.2%. Subsequently, the coupling equations are applied to different case studies such as slab tapered waveguide and lossy “turn-on” waveguide. The transmission spectrum and field pattern distribution show that the lossy waveguide has a large radiation loss with an average transmission efficiency of less than 5%. The slab tapered waveguide can have more than 90% transmission efficiency with the convex curvature. The exact step-coupling theory can be applied to a vast range of geometrical variation photonic crystal based waveguides and it has quick and accurate convergence simulation results.

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