48 research outputs found

    First Study of Combined Blazar Light Curves with FACT and HAWC

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    For studying variable sources like blazars, it is crucial to achieve unbiased monitoring, either with dedicated telescopes in pointing mode or survey instruments. At TeV energies, the High Altitude Water Cherenkov (HAWC) observatory monitors approximately two thirds of the sky every day. It uses the water Cherenkov technique, which provides an excellent duty cycle independent of weather and season. The First G-APD Cherenkov Telescope (FACT) monitors a small sample of sources with better sensitivity, using the imaging air Cherenkov technique. Thanks to its camera with silicon-based photosensors, FACT features an excellent detector performance and stability and extends its observations to times with strong moonlight, increasing the duty cycle compared to other imaging air Cherenkov telescopes. As FACT and HAWC have overlapping energy ranges, a joint study can exploit the longer daily coverage given that the observatories' locations are offset by 5.3 hours. Furthermore, the better sensitivity of FACT adds a finer resolution of features on hour-long time scales, while the continuous duty cycle of HAWC ensures evenly sampled long-term coverage. Thus, the two instruments complement each other to provide a more complete picture of blazar variability. In this presentation, the first joint study of light curves from the two instruments will be shown, correlating long-term measurements with daily sampling between air and water Cherenkov telescopes. The presented results focus on the study of the variability of the bright blazars Mrk 421 and Mrk 501 during the last two years featuring various flaring activities.Comment: 6 pages, 2 figures. Contribution to the 6th International Symposium on High Energy Gamma-Ray Astronomy (Gamma2016), Heidelberg, Germany. To be published in the AIP Conference Proceeding

    NRW80+ Hochaltrigenstudie: Abschlussbericht zur ersten Förderphase 01/2016-12/2018

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    Der Abschlussbericht beschreibt die Ausgangslage, Vorarbeiten, Durchführung, erste Ergebnisse und Implikationen der Studie "Lebensqualität und Wohlbefinden hochaltriger Menschen in NRW" (NRW80+). Ziel der Studie war es, die Lebenssituation und Lebensqualität hochaltriger Menschen in Nordrhein-Westfalen umfassend zu untersuchen. Im Rahmen einer repräsentativen Querschnittsbefragung wurden Personen ab 80 Jahren befragt, wobei auch gesundheitlich beeinträchtigte (u.a. über Stellvertreter:innen-Interviews) und in Heimen lebende Hochaltrige explizit eingeschlossen wurden. Die erhobenen Daten schließen diverse Aspekte der objektiven Lebens- und Ressourcenlagen sowie der subjektiven Bewertungen und gesellschaftlichen Wertvorstellungen ein. In diesem Bericht werden die ersten deskriptiven Ergebnisse zu Themen wie allgemeine Lebenszufriedenheit, Depressivität, subjektive Gesundheit, Pflegebedürftigkeit und Pflegenutzung, soziale Netzwerke, Anomie und Internetnutzung dargestellt. Darüber hinaus wird auf Basis von beispielhaften multivariaten Analysen beschrieben, wie die Verfügbarkeit von Lebensqualitätsresourcen (z.B. Gesundheit, Freizeitgestaltung) zur Erklärung von Ungleichheiten in Lebensqualitätsoutcomes (z.B. Lebenszufriedenheit, Wertschätzung) beiträgt. Neben den Ergebnissen der quantitativen Erhebung werden auch Befunde aus den teilstandardisierten leitfadengestützten Interviews mit Stakeholdern vorgestellt, die aus gesellschaftlich relevanten Handlungs- und Entscheidungsfeldern stammen

    The relentless variability of Mrk 421 from the TeV to the radio

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    The origin of the gamma-ray emission of the blazar Mrk 421 is still a matter of debate. We used 5.5 years of unbiased observing campaign data, obtained using the FACT telescope and the Fermi LAT detector at TeV and GeV energies, the longest and densest so far, together with contemporaneous multi-wavelength observations, to characterise the variability of Mrk 421 and to constrain the underlying physical mechanisms. We studied and correlated light curves obtained by ten different instruments and found two significant results. The TeV and X-ray light curves are very well correlated with a lag of <0.6 days. The GeV and radio (15 Ghz band) light curves are widely and strongly correlated. Variations of the GeV light curve lead those in the radio. Lepto-hadronic and purely hadronic models in the frame of shock acceleration predict proton acceleration or cooling timescales that are ruled out by the short variability timescales and delays observed in Mrk 421. Instead the observations match the predictions of leptonic models.Comment: 10 pages, 8 figures, 1 tabl

    ContribuciĂłn al conocimiento de Porosagrotis gypaetina (Guen.) (Lep.:Noctuidae)

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    p.15-22Este trabajo tiene por finalidad brindar una descripcion detallada de los diferentes estados de desarrollo, asi como de los estadios larvales, de Porosagrotis gypaetina (Guen.) y estimar sus principales parametros biologicos. Se trata de una oruga conocida vulgarmente como gusano pardo que frecuenta cultivos de alfalfa, trebol bianco, maiz y girasol y determinadas malezas. Los caracteres considerados para su identificacion fueron, en el huevo: numero y distribucion de costas; en la larva: pigmentacion, distribucion de manchas y cerdas corporales; en la pupa: tamaño, forma y color y caracteristicas del cremaster; y en el adulto: ubicacion y coloracion de maculas y nervaduras alares. La emergencia de imagos alcanzo su maximo en abril y mayo. El periodo embrionario se completo en 22 a 26 dias. Aproximadamente la mitad de las larvas cumplieron su ciclo en 6 estadios y las restantes en 7; la duracion total del periodo larval fue de 134 a 141 dias, sin considerar la forma prepupal e independientemente del numero de estadios. Las orugas permanecieron como prepupas durante la temporada estival (aproximadamente 161 dias). El estado pupal duro 40 a 57 dias. Las observaciones realizadas permiten expresar que, inediante los caracteres descriptos, es factible reconocer la especie a traves no solo de los adultos, sino de sus estados inmaduros. Posee una sola generacion anual; transcurre el inviemo como larva; el daño tipico de corte lo produce a partir del cuarto estadio larval

    Providing Information by Resource- Constrained Data Analysis

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    The Collaborative Research Center SFB 876 (Providing Information by Resource-Constrained Data Analysis) brings together the research fields of data analysis (Data Mining, Knowledge Discovery in Data Bases, Machine Learning, Statistics) and embedded systems and enhances their methods such that information from distributed, dynamic masses of data becomes available anytime and anywhere. The research center approaches these problems with new algorithms respecting the resource constraints in the different scenarios. This Technical Report presents the work of the members of the integrated graduate school

    Fractional variability—a tool to study blazar variability

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    Active Galactic Nuclei emit radiation over the whole electromagnetic spectrum up to TeV energies. Blazars are one subtype with their jets pointing towards the observer. One of their typical features is extreme variability on timescales, from minutes to years. The fractional variability is an often used parameter for investigating the degree of variability of a light curve. Different detection methods and sensitivities of the instruments result in differently binned data and light curves with gaps. As they can influence the physics interpretation of the broadband variability, the effects of these differences on the fractional variability need to be studied. In this paper, we study the systematic effects of completeness in time coverage and the sampling rate. Using public data from instruments monitoring blazars in various energy ranges, we study the variability of the bright TeV blazars Mrk 421 and Mrk 501 over the electromagnetic spectrum, taking into account the systematic effects, and compare our findings with previous results. Especially in the TeV range, the fractional variability is higher than in previous studies, which can be explained by the much longer (seven years compared to few weeks) and more complete data sample
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