2,865 research outputs found

    Atomic Processes in Planetary Nebulae and H II Regions

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    Spectroscopic studies of Planetary Nebulae (PNe) and H {\sc ii} regions have driven much development in atomic physics. In the last few years the combination of a generation of powerful observatories, the development of ever more sophisticated spectral modeling codes, and large efforts on mass production of high quality atomic data have led to important progress in our understanding of the atomic spectra of such astronomical objects. In this paper I review such progress, including evaluations of atomic data by comparisons with nebular spectra, detection of spectral lines from most iron-peak elements and n-capture elements, observations of hyperfine emission lines and analysis of isotopic abundances, fluorescent processes, and new techniques for diagnosing physical conditions based on recombination spectra. The review is directed toward atomic physicists and spectroscopists trying to establish the current status of the atomic data and models and to know the main standing issues.Comment: 9 pages, 1 figur

    Technical Evolution of Ceramic Tile Printing

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    [EN] Ceramic tile decorating techniques have evolved significantly in recent years. Digital inkjet printing technology has enabled digital systems to be used for the direct decoration of ceramic tiles, revolutionizing ceramic tile decoration and providing many advantages over traditional decoration techniques. It was the formulation of inks with soluble and vitrifiable stains that allowed inkjet printing technology to be introduced into ceramic tile decoration. The incorporation of milled inorganic pigments into the inks broadened the available color palette. However, the colloidal instability of these inks and the constraints of the printing heads themselves made it necessary to reduce pigment particle size, thus limiting color saturation and the color gamut. In order to increase color saturation and obtain a set of pigmented inks with colors more closely resembling CMYK colors, pigments with larger particle sizes need to be used. Indeed, other digital decorating techniques, such as xerography, allow larger particle sizes to be used, while also providing the advantages associated with digital decoration. However, the implementation of this technique for ceramic tile decoration requires the development of appropriate ceramic toners and adaptation of printing machines. This article reviews the technical evolution of ceramic tile printing and describes the development of a prototype, based on xerographic printing, that is able to print ceramic tiles directly and provides greater color intensity and a wider color gamut.40140756

    From Scattering in Black Hole Backgrounds to Higher-Spin Amplitudes: Part I

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    The scattering of massless waves of helicity h=0,12,1|h|=0,\frac{1}{2},1 in Schwarzschild and Kerr backgrounds is revisited in the long-wavelenght regime. Using a novel description of such backgrounds in terms of gravitating massive particles, we compute classical wave scattering in terms of 222\to 2 QFT amplitudes in flat space, to all orders in spin. The results are Newman-Penrose amplitudes which are in direct correspondence with solutions of the Regge-Wheeler/Teukolsky equation. By introducing a precise prescription for the point-particle limit, in Part I of this work we show how both agree for h=0h=0 at finite values of the scattering angle and arbitrary spin orientation. Associated classical observables such as the scattering cross sections, wave polarizations and time delay are studied at all orders in spin. The effect of the black hole spin on the polarization and helicity of the waves is found in agreement with previous analysis at linear order in spin. In the particular limit of small scattering angle, we argue that wave scattering admits a universal, point-particle description determined by the eikonal approximation. We show how our results recover the scattering eikonal phase with spin up to second post-Minkowskian order, and match it to the effective action of null geodesics in a Kerr background. Using this correspondence we derive classical observables such as polar and equatorial scattering angles. This study serves as a preceding analysis to Part II, where the Gravitational Wave (h=2h=2) case will be studied in detail

    Strategies in Maximizing the Use of Existing Technology in Philippine Schools

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    One of the challenges that continue to confront teachers in Philippine schools is the accessibility of technology for the study and learning of mathematics. In this paper, we will look at several situations and actual experiences happening in Philippine schools. Strategies on how existing technological tools are to be maximized will be discussed, including the creation of lesson plans and classroom activities. The use of technology-based manipulatives in mathematics learning as alternatives to unavailable technology will also be looked at

    Introducción

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    La versión en PDF se generó a partir de los archivos editables de Indesign CC2020 correspondientes a la primera edición digital

    Movilidad indiana en la corte de Madrid durante el siglo XVII: mercedes de hábito, “Patria común” y entramados clientelares

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    El presente artículo se aproxima al papel de la movilidad de los indianos y su lugar en el conjunto de la monarquía durante el siglo XVII. A partir de las pruebas de Juan de Cervantes y Cervantes, descendiente de una de las principales familias del patriciado urbano mexicano, para ingresar a la orden de caballería de Santiago en 1670, se revisa el entramado transatlántico de sus testigos, los cambios en la movilidad indiana con respecto a su padre y abuelo, también caballeros de Santiago, y la centralidad de sus agentes en los negocios de las Indias en la corte de Madrid

    Gobernar: la Audiencia Real de México en 1624

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    La versión en PDF se generó a partir de los archivos editables de Indesign CC2020 correspondientes a la primera edición digital

    Perdonar: los rebeldes mexicanos y el perdón del rey

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    La versión en PDF se generó a partir de los archivos editables de Indesign CC2020 correspondientes a la primera edición digital

    Combatir: la rebelión de 1624 en la ciudad de México

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    La versión en PDF se generó a partir de los archivos editables de Indesign CC2020 correspondientes a la primera edición digital
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