986 research outputs found

    Blazar Flaring Patterns (B-FlaP): Classifying Blazar Candidates of Uncertain type in the third Fermi-LAT catalog by Artificial Neural Networks

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    The Fermi Large Area Telescope (LAT) is currently the most important facility for investigating the GeV γ\gamma-ray sky. With Fermi LAT more than three thousand γ\gamma-ray sources have been discovered so far. 1144 (40%\sim40\%) of the sources are active galaxies of the blazar class, and 573 (20%\sim20\%) are listed as Blazar Candidate of Uncertain type (BCU), or sources without a conclusive classification. We use the Empirical Cumulative Distribution Functions (ECDF) and the Artificial Neural Networks (ANN) for a fast method of screening and classification for BCUs based on data collected at γ\gamma-ray energies only, when rigorous multiwavelength analysis is not available. Based on our method, we classify 342 BCUs as BL Lacs and 154 as FSRQs, while 77 objects remain uncertain. Moreover, radio analysis and direct observations in ground-based optical observatories are used as counterparts to the statistical classifications to validate the method. This approach is of interest because of the increasing number of unclassified sources in Fermi catalogs and because blazars and in particular their subclass High Synchrotron Peak (HSP) objects are the main targets of atmospheric Cherenkov telescopes.Comment: 18 pages, 17 figures, accepted for publication on MNRA

    An Austrian in Hollywood: The representation of foreigners in the films of Billy Wilder

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    This paper examines the work of Billy Wilder whose rich cinematic production frequently involves the collision of different languages as well as the clash of dissimilar cultures. As an Austrian living in the USA, the director had the privilege of gaining insight into his adopted culture from the point of view of an outsider - a bilingual "other" who made 25 films in almost 40 years of working in Hollywood. His films recurrently depict foreign characters at which Wilder pokes fun whether they are English, French, German, Italian, Russian or even the Americans of his adopted country. More precisely, the paper offers an overview of the multi-modal portrayals of diverse "foreigners," with examples taken from a small but significant sample of Wilder's films. The subtitling of dialogue in the secondary language for the target English-speaking audience and the specific translation solutions are not within the scope of this discussion, instead we focus on the comic collision of two languages and more importantly, on the way Wilder implements humour to highlight the absurdity of cultural difference. In other words, our main goal is to explore two or more languages in contrast when they become a humorous trope

    Optical counterparts of undetermined type γ\gamma-ray Active Galactic Nuclei with blazar-like Spectral Energy Distributions

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    During its first four years of scientific observations, the Fermi Large Area Telescope (Fermi-LAT) detected 3033 γ\gamma-ray sources above a 4σ\sigma significance level. Although most of the extra-Galactic sources are active galactic nuclei (AGN) of the blazar class, other families of AGNs are observed too, while a still high fraction of detections (30%\sim 30\%) remains with uncertain association or classification. According to the currently accepted interpretation, the AGN γ\gamma-ray emission arises from inverse Compton (IC) scattering of low energy photons by relativistic particles confined in a jet that, in the case of blazars, is oriented very close to our line of sight. Taking advantage of data from radio and X-ray wavelengths, which we expect to be produced together with γ\gamma-rays, providing a much better source localization potential, we focused our attention on a sample of γ\gamma-ray Blazar Candidates of Undetermined Type (BCUs), starting a campaign of optical spectroscopic observations. The main aims of our investigation include a census of the AGN families that contribute to γ\gamma-ray emission and a study of their redshift distribution, with the subsequent implications on the intrinsic source power. We furthermore analyze which γ\gamma-ray properties can better constrain the nature of the source, thus helping in the study of objects not yet associated with a reliable low frequency counterpart. In this communication we report on the instruments and techniques used to identify the optical counterparts of γ\gamma-ray sources, we give an overview on the status of our work, and we discuss the implications of a large scale study of γ\gamma-ray emitting AGNs.Comment: 9 pages, 2 figures, proceedings of the 10th Serbian Conference on Spectral Line Shapes in Astrophysics. JOAA, accepte

    Characterization of compacted coal wash as structural fill material

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    In this paper, detailed laboratory investigations were conducted on coal wash produced at coal mine, Wollongong, New South Wales, Australia. Geotechnical tests were conducted to determine the particle size distribution, compaction characteristics, shear resistance and collapse potential. The compaction tests were conducted under dry and submerged condition to examine the compactability and the strength of the coal wash. The test shows that compacted coal wash has good potential as effective fill for embankments, and land reclamation. Although when coal wash is compacted under submerged condition, increased level of compaction has minimal effect
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