537 research outputs found

    D4.1. Technologies and tools for corpus creation, normalization and annotation

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    The objectives of the Corpus Acquisition and Annotation (CAA) subsystem are the acquisition and processing of monolingual and bilingual language resources (LRs) required in the PANACEA context. Therefore, the CAA subsystem includes: i) a Corpus Acquisition Component (CAC) for extracting monolingual and bilingual data from the web, ii) a component for cleanup and normalization (CNC) of these data and iii) a text processing component (TPC) which consists of NLP tools including modules for sentence splitting, POS tagging, lemmatization, parsing and named entity recognition

    Unprecedented study of the broadband emission of Mrk 421 during flaring activity in March 2010

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    Context. Because of its proximity, Mrk 421 is one of the best sources on which to study the nature of BL Lac objects. Its proximity allows us to characterize its broadband spectral energy distribution (SED). Aims. The goal is to better understand the mechanisms responsible for the broadband emission and the temporal evolution of Mrk 421. These mechanisms may also apply to more distant blazars that cannot be studied with the same level of detail. Methods. A flare occurring in March 2010 was observed for 13 consecutive days (from MJD 55 265 to MJD 55 277) with unprecedented wavelength coverage from radio to very high energy (VHE; E> 100 GeV) γ-rays with MAGIC, VERITAS, Whipple, Fermi-LAT, MAXI, RXTE, Swift, GASP-WEBT, and several optical and radio telescopes. We modeled the day-scale SEDs with one-zone and two-zone synchrotron self-Compton (SSC) models, investigated the physical parameters, and evaluated whether the observed broadband SED variability can be associated with variations in the relativistic particle population. Results. The activity of Mrk 421 initially was high and then slowly decreased during the 13-day period. The flux variability was remarkable at the X-ray and VHE bands, but it was minor or not significant at the other bands. The variability in optical polarization was also minor. These observations revealed an almost linear correlation between the X-ray flux at the 2–10 keV band and the VHE γ-ray flux above 200 GeV, consistent with the γ-rays being produced by inverse-Compton scattering in the Klein-Nishina regime in the framework of SSC models. The one-zone SSC model can describe the SED of each day for the 13 consecutive days reasonably well, which once more shows the success of this standard theoretical scenario to describe the SEDs of VHE BL Lacs such as Mrk 421. This flaring activity is also very well described by a two-zone SSC model, where one zone is responsible for the quiescent emission, while the other smaller zone, which is spatially separated from the first, contributes to the daily variable emission occurring at X-rays and VHE γ-rays. The second blob is assumed to have a smaller volume and a narrow electron energy distribution with 3 × 104<γ< 6 × 105, where γ is the Lorentz factor of the electrons. Such a two-zone scenario would naturally lead to the correlated variability at the X-ray and VHE bands without variability at the optical/UV band, as well as to shorter timescales for the variability at the X-ray and VHE bands with respect to the variability at the other bands. Conclusions. Both the one-zone and the two-zone SSC models can describe the daily SEDs via the variation of only four or five model parameters, under the hypothesis that the variability is associated mostly with the underlying particle population. This shows that the particle acceleration and cooling mechanism that produces the radiating particles might be the main mechanism responsible for the broadband SED variations during the flaring episodes in blazars. The two-zone SSC model provides a better agreement with the observed SED at the narrow peaks of the low- and high-energy bumps during the highest activity, although the reported one-zone SSC model could be further improved by varying the parameters related to the emitting region itself (δ, B and R), in addition to the parameters related to the particle population.Fil: Aleksic, J.. IFAE; EspañaFil: Ansoldi, S.. Università di Udine; ItaliaFil: Antonelli, L. A.. INAF National Institute for Astrophysics; ItaliaFil: Antoranz, P.. Università di Siena; ItaliaFil: Babic, A.. University of Rijeka; CroaciaFil: Bangale, P.. Max-Planck-Institut für Physik; AlemaniaFil: Barres de Almeida, U.. Max-Planck-Institut für Physik; AlemaniaFil: Barrio, J. A.. Universidad Complutense de Madrid; EspañaFil: Becerra Gonzalez, J.. Inst. de Astrofísica de Canarias; EspañaFil: Bednarek, W.. University of Łódź,; PoloniaFil: Bernardini, E.. Deutsches Elektronen-Synchrotron (DESY); AlemaniaFil: Biasuzzi, B.. Università di Udine; ItaliaFil: Biland, A.. ETH Zurich; SuizaFil: Blanch, O.. IFAE; EspañaFil: Boller, A.. ETH Zurich; SuizaFil: Bonnefoy, S.. Universidad Complutense de Madrid; EspañaFil: Bonnoli, G.. INAF National Institute for Astrophysics ; ItaliaFil: Borracci, F.. Max-Planck-Institut für Physik; AlemaniaFil: Bretz, T.. Universität Würzburg ; AlemaniaFil: Carmona, E.. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas ; EspañaFil: Carosi, A.. INAF National Institute for Astrophysics; ItaliaFil: Colin, P.. Max-Planck-Institut für Physik; AlemaniaFil: Colombo, E.. Inst. de Astrofísica de Canarias; EspañaFil: Contreras, J. L.. Universidad Complutense; EspañaFil: Cortina, J.. IFAE; EspañaFil: Covino, S.. INAF National Institute for Astrophysics; ItaliaFil: Da Vela, P.. Università di Siena; ItaliaFil: Dazzi, F.. Max-Planck-Institut für Physik; AlemaniaFil: Pichel, Ana Carolina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Rovero, Adrian Carlos. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: The Veritas Collaboration.Fil: The MAGIC Collaboration

    The major upgrade of the MAGIC telescopes, Part II: A performance study using observations of the Crab Nebula

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    MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes located in the Canary island of La Palma, Spain. During summer 2011 and 2012 it underwent a series of upgrades, involving the exchange of the MAGIC-I camera and its trigger system, as well as the upgrade of the readout system of both telescopes. We use observations of the Crab Nebula taken at low and medium zenith angles to assess the key performance parameters of the MAGIC stereo system. For low zenith angle observations, the standard trigger threshold of the MAGIC telescopes is ~50GeV. The integral sensitivity for point-like sources with Crab Nebula-like spectrum above 220GeV is (0.66+/-0.03)% of Crab Nebula flux in 50 h of observations. The angular resolution, defined as the sigma of a 2-dimensional Gaussian distribution, at those energies is < 0.07 degree, while the energy resolution is 16%. We also re-evaluate the effect of the systematic uncertainty on the data taken with the MAGIC telescopes after the upgrade. We estimate that the systematic uncertainties can be divided in the following components: < 15% in energy scale, 11-18% in flux normalization and +/-0.15 for the energy spectrum power-law slope.Comment: 21 pages, 25 figures, accepted for publication in Astroparticle Physic

    The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies

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    Aims: We perform an extensive characterization of the broadband emission of Mrk 421, as well as its temporal evolution, during the non-flaring (low) state. The high brightness and nearby location (z = 0.031) of Mrk 421 make it an excellent laboratory to study blazar emission. The goal is to learn about the physical processes responsible for the typical emission of Mrk 421, which might also be extended to other blazars that are located farther away and hence are more difficult to study. Methods: We performed a 4.5-month multi-instrument campaign on Mrk 421 between January 2009 and June 2009, which included VLBA, F-GAMMA, GASP-WEBT, Swift, RXTE, Fermi-LAT, MAGIC, and Whipple, among other instruments and collaborations. This extensive radio to very-high-energy (VHE; E> 100 GeV) γ-ray dataset provides excellent temporal and energy coverage, which allows detailed studies of the evolution of the broadband spectral energy distribution. Results: Mrk421 was found in its typical (non-flaring) activity state, with a VHE flux of about half that of the Crab Nebula, yet the light curves show significant variability at all wavelengths, the highest variability being in the X-rays. We determined the power spectral densities (PSD) at most wavelengths and found that all PSDs can be described by power-laws without a break, and with indices consistent with pink/red-noise behavior. We observed a harder-when-brighter behavior in the X-ray spectra and measured a positive correlation between VHE and X-ray fluxes with zero time lag. Such characteristics have been reported many times during flaring activity, but here they are reported for the first time in the non-flaring state. We also observed an overall anti-correlation between optical/UV and X-rays extending over the duration of the campaign. Conclusions: The harder-when-brighter behavior in the X-ray spectra and the measured positive X-ray/VHE correlation during the 2009 multi-wavelength campaign suggests that the physical processes dominating the emission during non-flaring states have similarities with those occurring during flaring activity. In particular, this observation supports leptonic scenarios as being responsible for the emission of Mrk 421 during non-flaring activity. Such a temporally extended X-ray/VHE correlation is not driven by any single flaring event, and hence is difficult to explain within the standard hadronic scenarios. The highest variability is observed in the X-ray band, which, within the one-zone synchrotron self-Compton scenario, indicates that the electron energy distribution is most variable at the highest energies.Fil: Aleksic, J.. IFAE; EspañaFil: Ansoldi, S.. Università di Udine; ItaliaFil: Antonelli, L. A.. INAF National Institute for Astrophysics; ItaliaFil: Antoranz, P.. Università di Siena; ItaliaFil: Babic, A.. University of Rijeka; CroaciaFil: Bangale, P.. Max-Planck-Institut für Physik; AlemaniaFil: Barres de Almeida, U.. Max-Planck-Institut für Physik; AlemaniaFil: Barrio, J. A.. Universidad Complutense de Madrid; EspañaFil: Becerra Gonzalez, J.. Inst. de Astrofísica de Canarias; EspañaFil: Bednarek, W.. University of Lodz; PoloniaFil: Berger, K.. Inst. de Astrofísica de Canarias; EspañaFil: Bernardini, E.. Deutsches Elektronen-Synchrotron (DESY); AlemaniaFil: Bijand, A.. ETH Zurich; SuizaFil: Blanch, O.. IFAE; EspañaFil: Bock, R. K.. Max-Planck-Institut für Physik; AlemaniaFil: Bonnefoy, S.. Universidad Complutense; EspañaFil: Bonnoli, G.. INAF National Institute for Astrophysics; ItaliaFil: Borracci, F.. Max-Planck-Institut für Physik; AlemaniaFil: Bretz, T.. Universität Würzburg,; AlemaniaFil: Carmona, E.. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas; EspañaFil: Carosi, A.. INAF National Institute for Astrophysics; EspañaFil: Carreto Fidalgo, D.. Universität Würzburg; AlemaniaFil: Colin, P.. Max-Planck-Institut für Physik; AlemaniaFil: Colombo, E.. Inst. de Astrofísica de Canarias; EspañaFil: Contreras, J. L.. Universidad Complutense; EspañaFil: Cortina, J.. IFAE; EspañaFil: Covino, S.. INAF National Institute for Astrophysics; ItaliaFil: Pichel, Ana Carolina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Rovero, Adrian Carlos. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: The Magic Collaboration.Fil: The Veritas Collaboration

    Multiwavelength observations of Mrk 501 in 2008

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    Context. Blazars are variable sources on various timescales over a broad energy range spanning from radio to very high energy (>100 GeV, hereafter VHE). Mrk 501 is one of the brightest blazars at TeV energies and has been extensively studied since its first VHE detection in 1996. However, most of the γ-ray studies performed on Mrk 501 during the past years relate to flaring activity, when the source detection and characterization with the available γ-ray instrumentation was easier toperform. Aims: Our goal is to characterize the source γ-ray emission in detail, together with the radio-to-X-ray emission, during the non-flaring (low) activity, which is less often studied than the occasional flaring (high) activity. Methods: We organized a multiwavelength (MW) campaign on Mrk 501 between March and May 2008. This multi-instrument effort included the most sensitive VHE γ-ray instruments in the northern hemisphere, namely the imaging atmospheric Cherenkov telescopes MAGIC and VERITAS, as well as Swift, RXTE, the F-GAMMA, GASP-WEBT, and other collaborations and instruments. This provided extensive energy and temporal coverage of Mrk 501 throughout the entire campaign. Results: Mrk 501 was found to be in a low state of activity during the campaign, with a VHE flux in the range of 10%-20% of the Crab nebula flux. Nevertheless, significant flux variations were detected with various instruments, with a trend of increasing variability with energy and a tentative correlation between the X-ray and VHE fluxes. The broadband spectral energy distribution during the two different emission states of the campaign can be adequately described within the homogeneous one-zone synchrotron self-Compton model, with the (slightly) higher state described by an increase in the electron number density. Conclusions: The one-zone SSC model can adequately describe the broadband spectral energy distribution of the source during the two months covered by the MW campaign. This agrees with previous studies of the broadband emission of this source during flaring and non-flaring states. We report for the first time a tentative X-ray-to-VHE correlation during such a low VHE activity. Although marginally significant, this positive correlation between X-ray and VHE, which has been reported many times during flaring activity, suggests that the mechanisms that dominate the X-ray/VHE emission during non-flaring-activity are not substantially different from those that are responsible for the emission during flaring activity.Fil: Aleksic, J.. IFAE; EspañaFil: Ansoldi, S.. Università di Udine; ItaliaFil: Antonelli, L. A.. INAF National Institute for Astrophysics; ItaliaFil: Antoranz, P.. Università di Siena; ItaliaFil: Babic, A.. University of Rijeka ; Croacia. University of Split; CroaciaFil: Bangale, P.. Max-Planck-Institut für Physik; AlemaniaFil: Barres de Almeida, U.. Max-Planck-Institut für Physik; AlemaniaFil: Barrio, J. A.. Universidad Complutense de Madrid; EspañaFil: Becerra Gonzalez, J.. Inst. de Astrofísica de Canarias; EspañaFil: Bednarek, W.. University of Lodz; PoloniaFil: Berger, K.. Inst. de Astrofísica de Canarias; EspañaFil: Bernardini, E.. Deutsches Elektronen-Synchrotron (DESY); AlemaniaFil: Biland, A.. ETH Zurich; SuizaFil: Blanch, O.. IFAE; EspañaFil: Bock, R. K.. Max-Planck-Institut für Physik; AlemaniaFil: Bonnefoy, S.. Universidad Complutense de Madrid; EspañaFil: Bonnoli, G.. INAF National Institute for Astrophysics; ItaliaFil: Borracci, F.. Max-Planck-Institut für Physik; AlemaniaFil: Bretz, T.. Universität Würzburg; Alemania. Now at École polytechnique fédérale de Lausanne (EPFL); SuizaFil: Carmona, E.. Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas; EspañaFil: Carosi, A.. INAF National Institute for Astrophysics; ItaliaFil: Carreto Fidalgo, D.. Universität Würzburg; AlemaniaFil: Colin, P.. Max-Planck-Institut für Physik; AlemaniaFil: Colombo, E.. Inst. de Astrofísica de Canarias; EspañaFil: Contreras, J. L.. Universidad Complutense de Madrid; EspañaFil: Cortina, J.. IFAE; EspañaFil: Covino, S.. INAF National Institute for Astrophysics; ItaliaFil: Da Vela, P.. Università di Siena; ItaliaFil: Dazzi, F.. Università di Udine; ItaliaFil: Pichel, Ana Carolina. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: The MAGIC collaboration.Fil: The VERITAS collaboration

    Reliability of Monte Carlo event generators for gamma-ray dark matter searches

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    We study the differences in the gamma-ray spectra simulated by four Monte Carlo event generator packages developed in particle physics. Two different versions of PYTHIA and two of HERWIG are analyzed, namely PYTHIA 6.418 and HERWIG 6.5.10 in Fortran and PYTHIA 8.165 and HERWIG 2.6.1 in C++. For all the studied channels, the intrinsic differences between them are shown to be significative and may play an important role in misunderstanding dark matter signals

    Monovalent engagement of the BCR activates ovalbumin-specific transnuclear B cells

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    Valency requirements for B cell activation upon antigen encounter are poorly understood. OB1 transnuclear B cells express an IgG1 B cell receptor (BCR) specific for ovalbumin (OVA), the epitope of which can be mimicked using short synthetic peptides to allow antigen-specific engagement of the BCR. By altering length and valency of epitope-bearing synthetic peptides, we examined the properties of ligands required for optimal OB1 B cell activation. Monovalent engagement of the BCR with an epitope-bearing 17-mer synthetic peptide readily activated OB1 B cells. Dimers of the minimal peptide epitope oriented in an N to N configuration were more stimulatory than their C to C counterparts. Although shorter length correlated with less activation, a monomeric 8-mer peptide epitope behaved as a weak agonist that blocked responses to cell-bound peptide antigen, a blockade which could not be reversed by CD40 ligation. The 8-mer not only delivered a suboptimal signal, which blocked subsequent responses to OVA, anti-IgG, and anti-kappa, but also competed for binding with OVA. Our results show that fine-tuning of BCR-ligand recognition can lead to B cell nonresponsiveness, activation, or inhibition

    The Dark Energy Survey: more than dark energy – an overview

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    This overview paper describes the legacy prospect and discovery potential of the Dark Energy Survey (DES) beyond cosmological studies, illustrating it with examples from the DES early data. DES is using a wide-field camera (DECam) on the 4 m Blanco Telescope in Chile to image 5000 sq deg of the sky in five filters (grizY). By its completion, the survey is expected to have generated a catalogue of 300 million galaxies with photometric redshifts and 100 million stars. In addition, a time-domain survey search over 27 sq deg is expected to yield a sample of thousands of Type Ia supernovae and other transients. The main goals of DES are to characterize dark energy and dark matter, and to test alternative models of gravity; these goals will be pursued by studying large-scale structure, cluster counts, weak gravitational lensing and Type Ia supernovae. However, DES also provides a rich data set which allows us to study many other aspects of astrophysics. In this paper, we focus on additional science with DES, emphasizing areas where the survey makes a difference with respect to other current surveys. The paper illustrates, using early data (from ‘Science Verification’, and from the first, second and third seasons of observations), what DES can tell us about the Solar system, the Milky Way, galaxy evolution, quasars and other topics. In addition, we show that if the cosmological model is assumed to be _+cold dark matter, then important astrophysics can be deduced from the primary DES probes. Highlights from DES early data include the discovery of 34 trans-Neptunian objects, 17 dwarf satellites of the Milky Way, one published z > 6 quasar (and more confirmed) and two published superluminous supernovae (and more confirmed)

    Insulin/IGF and Sex Hormone Axes in Human Endometrium and Associations with Endometrial Cancer Risk Factors

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    Given an ordered set of points and an ordered set of geometric objects in the plane, we are interested in finding a non-crossing matching between point-object pairs. In this paper, we address the algorithmic problem of determining whether a non-crossing matching exists between a given point-object pair. We show that when the objects we match the points to are finite point sets, the problem is NP-complete in general, and polynomial when the objects are on a line or when their size is at most 2. When the objects are line segments, we show that the problem is NP-complete in general, and polynomial when the segments form a convex polygon or are all on a line. Finally, for objects that are straight lines, we show that the problem of finding a min-max non-crossing matching is NP-complete. © 2012 Elsevier B.V.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Design concepts for the Cherenkov Telescope Array CTA: an advanced facility for ground-based high-energy gamma-ray astronomy

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    Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA
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