182 research outputs found

    Los alcances del Desarrollo Inclusivo en el pensamiento de Carlos Llano

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    Aún cuando es poco probable que Carlos Llano (1932-2010) haya conocido el concepto de “Desarrollo Inclusivo”, en el conjunto de su obra se encuentran varias aportaciones que encajan con el fondo de esta idea, y que representan enfoques enriquecedores para el contenido en uso de esta noción. Se recoge, en primer lugar, su concepción del desarrollo de la persona humana y la relación de éste con el crecimiento económico. Otra idea fecunda es la revisión del papel que tiene la colaboración, por encima de la competencia, en la productividad de las empresas. Finalmente se propone una ampliación de lo que se entiende por inclusión, de modo que ésta no se restrinja sólo a ser una cualidad del desarrollo, sino un factor constitutivo de éste.Although it is unlikely that Carlos Llano (1932-2010) knew the concept of “Inclusive Growth”, in the whole body of his work there are several contributions that fit the background of this idea, and represent an enriching approach to the content in use of this notion. Firstly, his conception of the development of the human person and the relation of this with the economic growth is collected. Another fruitful idea is the revision of the role of collaboration, above competition, in the productivity of companies. Finally, an expansion of what is meant by inclusion is proposed, so that it is not restricted only to being a quality of development, but a constitutive factor of it

    El concepto de deliberación en el comentario de Santo Tomás de Aquino al libro VI de la ética a Nicómaco

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    Saber escoger lo mejor en cada momento se presenta como una tarea no siempre fácil. Más todavía en la actualidad donde las posibilidades de elección han aumentado desmesuradamente. Paradójicamente, este aumento,lejos de haber favorecido la satisfacción de nuestras necesidades, se ha convertido más bien en fuente de ansiedad y preocupación. El supuesto aumento de libertad que debería haber traído consigo el crecimiento de posibilidades de elección, no se ha traducido en el aumento proporcional de felicidad esperado1

    Photometry and spectroscopy of faint candidate spectrophotometric standard DA white dwarfs

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    We present precise photometry and spectroscopy for 23 candidate spectrophotometric standard white dwarfs. The selected stars are distributed in the Northern hemisphere and around the celestial equators and are all fainter than r ~ 16.5 mag. This network of stars, when established as standards, together with the three Hubble Space Telescope primary CALSPEC white dwarfs, will provide a set of spectrophotometric standards to directly calibrate data products to better than 1%. These new faint standard white dwarfs will have enough signal-to-noise ratio in future deep photometric surveys and facilities to be measured accurately while still avoiding saturation in such surveys. They will also fall within the dynamic range of large telescopes and their instruments for the foreseeable future. This paper discusses the provenance of the observational data for our candidate standard stars. The comparison with models, reconciliation with reddening, and the consequent derivation of the full spectral energy density distributions for each of them is reserved for a subsequent paper.Comment: 31 pages, 17 figures, 10 tables, ApJ in press (accepted on December 23rd, 2018

    Generalized Second Law and phantom Cosmology: accreting black holes

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    The accretion of phantom fields by black holes within a thermodynamic context is addressed. For a fluid violating the dominant energy condition, case of a phantom fluid, the Euler and Gibbs relations permit two different possibilities for the entropy and temperature: a situation in which the entropy is negative and the temperature is positive or vice-versa. In the former case, if the generalized second law (GSL) is valid, then the accretion process is not allowed whereas in the latter, there is a critical black hole mass below which the accretion process occurs. In a universe dominated by a phantom field, the critical mass drops quite rapidly with the cosmic expansion and black holes are only slightly affected by accretion. All black holes disappear near the big rip, as suggested by previous investigations, if the GSL is violated.Comment: 8 pp., no figure

    How to Tell a Jet from a Balloon: A Proposed Test for Beaming in Gamma Ray Bursts

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    If gamma ray bursts are highly collimated, the energy requirements of each event may be reduced by several (~ 4-6) orders of magnitude, and the event rate increased correspondingly. Extreme conditions in gamma ray bursters lead to highly relativistic motions (bulk Lorentz factors Gamma > 100). This results in strong forward beaming of the emitted radiation in the observer's rest frame. Thus, all information on gamma ray bursts comes from those ejecta emitted in a narrow cone (opening angle 1/Gamma) pointing towards the observer. We are at present ignorant of whether there are ejecta outside that cone or not. The recent detection of longer wavelength transients following gamma ray bursts allows an empirical test of whether gamma ray bursts are collimated jets or spherical fireballs. The bulk Lorentz factor of the burst ejecta will decrease with time after the event, as the ejecta sweep up the surrounding medium. Thus, radiation from the ejecta is beamed into an ever increasing solid angle as the burst remnant evolves. It follows that if gamma ray bursts are highly collimated, many more optical and radio transients should be observed without associated gamma rays than with them. Published supernova searches may contain enough data to test the most extreme models of gamma ray beaming. We close with a brief discussion of other possible consequences of beaming, including its effect on the evolution of burst remnants.Comment: Original replaced with accepted refereed manuscript. 11 pages, uses AASTeX 4.0 LaTeX macros. To be published in The Astrophysical Journal Letters, vol. 487, p. L1 (20 September 1997

    Late time cosmic acceleration from vacuum Brans-Dicke theory in 5D

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    We show that the scalar-vacuum Brans-Dicke equations in 5D are equivalent to Brans-Dicke theory in 4D with a self interacting potential and an effective matter field. The cosmological implication, in the context of FRW models, is that the observed accelerated expansion of the universe comes naturally from the condition that the scalar field is not a ghost, i.e., ω>3/2\omega > - 3/2. We find an effective matter-dominated 4D universe which shows accelerated expansion if 3/2<ω<1- 3/2 < \omega < - 1. We study the question of whether accelerated expansion can be made compatible with large values of ω\omega, within the framework of a 5D scalar-vacuum Brans-Dicke theory with variable, instead of constant, parameter ω\omega. In this framework, and based on a general class of solutions of the field equations, we demonstrate that accelerated expansion is incompatible with large values of ω\omega.Comment: In V2 the summary section is expanded. To be published in Classical and Quantum Gravity

    A Calibration of NICMOS Camera 2 for Low Count-Rates

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    NICMOS 2 observations are crucial for constraining distances to most of the existing sample of z > 1 SNe Ia. Unlike the conventional calibration programs, these observations involve long exposure times and low count rates. Reciprocity failure is known to exist in HgCdTe devices and a correction for this effect has already been implemented for high and medium count-rates. However observations at faint count-rates rely on extrapolations. Here instead, we provide a new zeropoint calibration directly applicable to faint sources. This is obtained via inter-calibration of NIC2 F110W/F160W with WFC3 in the low count-rate regime using z ~ 1 elliptical galaxies as tertiary calibrators. These objects have relatively simple near-IR SEDs, uniform colors, and their extended nature gives superior signal-to-noise at the same count rate than would stars. The use of extended objects also allows greater tolerances on PSF profiles. We find ST magnitude zeropoints (after the installation of the NICMOS cooling system, NCS) of 25.296 +- 0.022 for F110W and 25.803 +- 0.023 for F160W, both in agreement with the calibration extrapolated from count-rates 1,000 times larger (25.262 and 25.799). Before the installation of the NCS, we find 24.843 +- 0.025 for F110W and 25.498 +- 0.021 for F160W, also in agreement with the high-count-rate calibration (24.815 and 25.470). We also check the standard bandpasses of WFC3 and NICMOS 2 using a range of stars and galaxies at different colors and find mild tension for WFC3, limiting the accuracy of the zeropoints. To avoid human bias, our cross-calibration was "blinded" in that the fitted zeropoint differences were hidden until the analysis was finalized.Comment: Accepted for Publication in the Astronomical Journal. New version contains added referenc

    K Corrections For Type Ia Supernovae and a Test for Spatial Variation of the Hubble Constant

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    Cross-filter K corrections for a sample of "normal" Type Ia supernovae (SNe) have been calculated for a range of epochs. With appropriate filter choices, the combined statistical and systematic K correction dispersion of the full sample lies within 0.05 mag for redshifts z<0.7. This narrow dispersion of the calculated K correction allows the Type Ia to be used as a cosmological probe. We use the K corrections with observations of seven SNe at redshifts 0.3 < z <0.5 to bound the possible difference between the locally measured Hubble constant (H_L) and the true cosmological Hubble constant (H_0).Comment: 6 pages, 3 Postscript figures, uuencoded uses crckapb.sty and psfig.sty. To appear in Thermonuclear Supernovae (NATO ASI), eds. R. Canal, P. Ruiz-LaPuente, and J. Isern. Postscript version is also available at http://www-supernova.lbl.gov
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