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    Variable stars and stellar populations in Andromeda XXI: II. Another merged galaxy satellite of M31?

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    B and V time-series photometry of the M31 dwarf spheroidal satellite Andromeda XXI (And XXI) was obtained with the Large Binocular Cameras at the Large Binocular Telescope. We have identified 50 variables in And XXI, of which 41 are RR Lyrae stars (37 fundamental-mode RRab, and 4 first-overtone RRc, pulsators) and 9 are Anomalous Cepheids (ACs). The average period of the RRab stars ( = 0.64 days) and the period-amplitude diagram place And~XXI in the class of Oosterhoff II - Oosterhoff-Intermediate objects. From the average luminosity of the RR Lyrae stars we derived the galaxy distance modulus of (m-M)0_0=24.40±0.1724.40\pm0.17 mag, which is smaller than previous literature estimates, although still consistent with them within 1 σ\sigma. The galaxy color-magnitude diagram shows evidence for the presence of three different stellar generations in And~XXI: 1) an old (\sim 12 Gyr) and metal poor ([Fe/H]=-1.7 dex) component traced by the RR Lyrae stars; 2) a slightly younger (10-6 Gyr) and more metal rich ([Fe/H]=-1.5 dex) component populating the red horizontal branch, and 3) a young age (\sim 1 Gyr) component with same metallicity, that produced the ACs. Finally, we provide hints that And~XXI could be the result of a minor merging event between two dwarf galaxies.Comment: accepted for publications in Ap

    Инструменты и коммуникационные стратегии внешней политики в теории международных отношений

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    The purpose of this article is to analyze the nature of non-military instruments (economic sanctions, soft power and communication strategies) of foreign policy within the international relations theory, because these tools are becoming increasingly central to shaping strategic outcomes in the XXI centuryМета цієї статті - проаналізувати природу невійськових інструменти (економічні санкції, м'яка влада та комунікації стратегії) зовнішньої політики в рамках теорії міжнародних відносин, тому що ці інструменти стають все більш центральними у формуванні стратегічні результати у XXI стЦелью данной статьи является анализ характера невоенных инструменты (экономические санкции, мягкая сила и связь стратегии) ​​внешней политики в рамках теории международных отношений, потому что эти инструменты становятся все более важными для формирования стратегические итоги в XXI век

    XXI

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    Scattering states in Bethe-Salpeter equation

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    The off-mass shell scattering amplitude, satisfying the Bethe-Salpeter equation for spinless particles in Minkowski space with the ladder kernel, is computed for the first time.Comment: 7 pages, 3 figures. Presented at the XXI International Baldin Seminar on High Energy Physics Problems, September 10-15, 2012, JINR, Dubna, Russia. To be published in the online journal Proceedings of Science - PoS(Baldin ISHEPP XXI)027 (2012

    Book Review: Mirage (Kanal in Tamil)

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    Book review of Mirage (Kanal in Tamil). By K. Daniel. Translated by Subramaniam Jebanesan. Colombo, Sri Lanka: Kumaran Book House, 2016, xxi +321 pages
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