914 research outputs found

    PENG: integrated search of distributed news archives

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    The PENG system is intended to provide an integrated and personalized environment for news professionals, providing functionalities for filtering, distributed retrieval, and a flexible interface environment for the display and manipulation of news materials. In this paper we review the progress and results of the PENG system to date, and describe in detail the document filtering part of the system, which is designed to gather and filter documents to user profiles. The current architecture will be described, along with some of the main issues which have so far been found in it's development

    Probing dissipation mechanisms in BL Lac jets through X-ray polarimetry

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    The dissipation of energy flux in blazar jets plays a key role in the acceleration of relativistic particles. Two possibilities are commonly considered for the dissipation processes, magnetic reconnection -- possibly triggered by instabilities in magnetically-dominated jets -- , or shocks -- for weakly magnetized flows. We consider the polarimetric features expected for the two scenarios analyzing the results of state-of-the-art simulations. For the magnetic reconnection scenario we conclude, using results from global relativistic MHD simulations, that the emission likely occurs in turbulent regions with unstructured magnetic fields, although the simulations do not allow us to draw firm conclusions. On the other hand, with local particle-in-cell simulations we show that, for shocks with a magnetic field geometry suitable for particle acceleration, the self-generated magnetic field at the shock front is predominantly orthogonal to the shock normal and becomes quasi-parallel downstream. Based on this result we develop a simplified model to calculate the frequency-dependent degree of polarization, assuming that high-energy particles are injected at the shock and cool downstream. We apply our results to HBLs, blazars with the maximum of their synchrotron output at UV-soft X-ray energies. While in the optical band the predicted degree of polarization is low, in the X-ray emission it can ideally reach 50\%, especially during active/flaring states. The comparison between measurements in the optical and in the X-ray band made during active states (feasible with the planned {\it IXPE} satellite) are expected to provide valuable constraints on the dissipation and acceleration processes.Comment: 9 pages, 6 figures, accepted for publication by MNRA

    Using a task-based approach in evaluating the usability of BoBIs in an e-book environment

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    This paper reports on a usability evaluation of BoBIs (Back-of-the-book Indexes) as searching and browsing tools in an e-book environment. This study employed a task-based approach and within-subject design. The retrieval performance of a BoBI was compared with a ToC and Full-Text Search tool in terms of their respective effectiveness and efficiency for finding information in e-books. The results demonstrated that a BoBI was significantly more efficient (faster) and useful compared to a ToC or Full-Text Search tool for finding information in an e-book environment

    University of Strathclyde at TREC HARD

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    The motivation behind the University of Strathclyde's approach to this years HARD track was inspired from previous experiences by other participants, in particular research by [1], [3] and [4]. A running theme throughout these papers was the underlying hypothesis that a user's familiarity in a topic (i.e. their previous experience searching a subject), will form the basis for what type or style of document they will perceive as relevant. In other words, the user's context with regards to their previous search experience will determine what type of document(s) they wish to retrieve

    Optical spectroscopic observations of gamma-ray blazar candidates II. The 2013 KPNO campaign in the Northern Hemisphere

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    We recently started a systematic search of low-energy counterparts of the unidentified gamma-ray sources (UGSs) listed in the Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) and the Fermi-LAT 2-Year Source Catalog (2FGL).} The main goal of our investigation is to find active galaxies belonging to the blazar class that lie within the positional uncertainty region of the UGSs and thus could be their potential low-energy counterparts. To achieve our aims, we first adopted several procedures based on the peculiar observational properties of blazars in the radio and in the IR. Then we carried out a follow-up spectroscopic campaign in the optical band to verify the nature of the candidates selected as potential counterparts of the UGSs. Here we present the results of the observations carried out in 2013 in the Northern Hemisphere at Kitt Peak National Observatory (KPNO). Optical spectroscopy is crucial to confirm the nature of the sources and can be used to estimate their redshifts; it will also allow us to test the robustness of our methods when the whole campaign is completed. Here we present the optical spectroscopic observations of 39 sources. Within our sample we found that 6 sources are blazars, candidates to be low-energy counterparts of the UGSs listed in the 2FGL. We confirm that an additional 8 sources, previously classified as active galaxies of uncertain type and associated in the 2FGL, are also all BL Lac objects. Moreover, we also present 20 new spectra for known blazars listed in the Multi-frequency Catalogue of Blazars as having an uncertain redshift and/or being classified as BL Lac candidates. We conclude that our methods for selecting gamma-ray blazar candidates allows us to discover new blazars and increase the list of potential low-energy counterparts for the Fermi UGSs.Comment: 27 pages, 39 figures, 1 table, A&A accepted for publication (pre-proof version

    Pharmacokinetics (PK), pharmacodynamics (PD), and PK-PD integration of danofloxacin in sheep biological fluids

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    The fluoroquinolone antimicrobial drug danofloxacin was administered to sheep intravenously (i.v.) and intramuscularly (i.m.) at a dose of 1.25 mg/kg of body weight in a two-period crossover study. The pharmacokinetic properties of danofloxacin in serum, inflamed tissue cage fluid (exudate), and noninflamed tissue cage fluid (transudate) were established by using a tissue cage model. The in vitro and ex vivo activities of danofloxacin in serum, exudate, and transudate against a pathogenic strain of Mannheimia haemolytica were established. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the area under the curve (AUC)/MIC for serum, exudate, and transudate of 60.5, 85.6, and 45.7 h, respectively, after i.v. dosing and 55.9, 77.9, and 49.1 h, respectively, after i.m. dosing. After i.m. dosing, the maximum concentration/MIC ratios for serum, exudate, and transudate were 10.8, 3.0, and 1.6, respectively. The ex vivo growth inhibition data after i.m. dosing were fitted to the inhibitory sigmoid Emax equation to provide the values of AUC/MIC required to produce bacteriostasis, bactericidal activity, and elimination of bacteria. The respective values for serum were 17.8, 20.2, and 28.7 h, and slightly higher values were obtained for transudate and exudate. It is proposed that use of these data might provide a novel approach to the rational design of dosage schedules.Facultad de Ciencias Veterinaria

    Uso de fármacos en la hembra canina preñada

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    Physiological changes during pregnancy induce profound alterations in the pharmacokinetic pro­perties of many drugs. These changes affect the distribution, absorption, metabolism, and excretion of drugs and therefore may affect their pharmacodynamic properties. An understanding of both the physiology of pregnancy and the specific pharmacology of the different agents is necessary to achieve effective treatment and limit maternal and fetal risk. Unfortunately, most drug studies exclude pregnant females, even when there are pathological entities that need to be treated during pregnancy (pain, infectious processes, etc). This review begins with a reminder of the basic concepts of pharmacokinetics and their clinical relevance. Physiological changes in pregnancy and their consequences on the pharmacokinetic and pharmacodynamic properties of many drugs are described. As a closure, the therapeutic categories most commonly indicated in pregnant females are discussed.Los cambios fisiológicos en la preñez inducen alteraciones profundas en las propiedades farmacocinéticas de muchos medicamentos. Estos cambios afectan la absorción, la distribución, el metabolismo y la excreción de los fármacos y, por lo tanto, pueden afectar sus propiedades farmacodinámicas. Es necesario comprender tanto la fisiología de la preñez como la farmacología específica de los diferentes agentes para lograr un tratamiento eficaz y limitar el riesgo materno y fetal. Desafortunadamente, la mayoría de los estudios de medicamentos excluyen a las hembras preñadas, aún cuando existen entidades patológicas que requieren ser tratadas durante la preñez (dolor, procesos infecciosos, etc). Esta revisión se inicia con un recordatorio de los conceptos básicos de farmacocinética y su relevancia clínica. Se describen los cambios fisiológicos durante la preñez y sus consecuencias en las propiedades farmacocinéticas y farmacodinámicas de muchos medicamentos. Como cierre, se analizan de manera particular las categorías terapéuticas más comúnmente indicadas en hembras preñadas

    Optical archival spectra of blazar candidates of uncertain type in the 3rd^{rd} Fermi Large Area Telescope Catalog

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    Despite the fact that blazars constitute the rarest class among active galactic nuclei (AGNs) they are the largest known population of associated γ\gamma-ray sources. Many of the γ\gamma-ray objects listed in the Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar candidates of uncertain type (BCUs), either because they show multifrequency behaviour similar to blazars but lacking optical spectra in the literature, or because the quality of such spectra is too low to confirm their nature. Here we select, out of 585 BCUs in the 3FGL, 42 BCUs which we identify as probable blazars by their WISE infrared colors and which also have optical spectra that are available in the Sloan Digital Sky Survey (SDSS) and/or Six-Degree Field Galaxy Survey Database (6dFGS). We confirm the blazar nature of all of the sources. We furthermore conclude that 28 of them are BL Lacs, 8 are radio-loud quasars with flat radio spectrum and 6 are BL Lac whose emission is dominated by their host galaxy

    The Gamma-ray Blazar Quest: new optical spectra, state of art and future perspectives

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    We recently developed a procedure to recognize gamma-ray blazar candidates within the positional uncertainty regions of the unidentified/unassociated gamma-ray sources (UGSs). Such procedure was based on the discovery that Fermi blazars show peculiar infrared colors. However, to confirm the real nature of the selected candidates, optical spectroscopic data are necessary. Thus, we performed an extensive archival search for spectra available in the literature in parallel with an optical spectroscopic campaign aimed to reveal and confirm the nature of the selected gamma-ray blazar candidates. Here, we first search for optical spectra of a selected sample of gamma-ray blazar candidates that can be potential counterparts of UGSs using the Sloan Digital Sky Survey (SDSS DR12). This search enables us to update the archival search carried out to date. We also describe the state-of-art and the future perspectives of our campaign to discover previously unknown gamma-ray blazars.Comment: 11 pages, 2 figures, 5 tables, pre-proof version, accepted for publication of Astrophysics and Space Scienc
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