1,263 research outputs found

    La financiarización de las relaciones salariales. Una perspectiva internacional. Madrid, La Catarata, 2012

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    Para comprender las dimensiones económicas, políticas, ecológicas y, sobre todo, sociales, de la actual 'gran transformación' neoliberal en el sentido que Karl Polanyi le dio a este término, es necesario dar cuenta del proceso de financiarización, así como de sus múltiples y perniciosas consecuencias. En esta dirección se orienta la obra que aquí reseñamos La financiarización de las relaciones salariales. una perspectiva internacional

    Abundant Z-cyanomethanimine in the interstellar medium: paving the way to the synthesis of adenine

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    We report the first detection in the interstellar medium of the Z-isomer of cyanomethanimine (HNCHCN), an HCN dimer proposed as precursor of adenine. We identified six transitions of Z-cyanomethanimine, along with five transitions of E-cyanomethanimine, using IRAM 30m observations towards the Galactic Center quiescent molecular cloud G+0.693. The Z-isomer has a column density of (2.0±\pm0.6)×\times1014^{14} cm2^{-2} and an abundance of 1.5×\times109^{-9}. The relative abundance ratio between the isomers is [Z/E]\sim6. This value cannot be explained by the two chemical formation routes previously proposed (gas-phase and grain surface), which predicts abundances ratios between 0.9 and 1.5. The observed [Z/E] ratio is in good agreement with thermodynamic equilibrium at the gas kinetic temperature (130-210 K). Since isomerization is not possible in the ISM, the two species may be formed at high temperature. New chemical models, including surface chemistry on dust grains and gas-phase reactions, should be explored to explain our findings. Whatever the formation mechanism, the high abundance of Z-HNCHCN shows that precursors of adenine are efficiently formed in the ISM.Comment: Accepted in Monthly Notices of the Royal Astronomical Society Letter

    A bivariate return period based on copulas for hydrologic dam design: accounting for reservoir routing in risk estimation

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    A multivariate analysis on flood variables is needed to design some hydraulic structures like dams, as the complexity of the routing process in a reservoir requires a representation of the full hydrograph. In this work, a bivariate copula model was used to obtain the bivariate joint distribution of flood peak and volume, in order to know the probability of occurrence of a given inflow hydrograph. However, the risk of dam overtopping is given by the maximum water elevation reached during the routing process, which depends on the hydrograph variables, the reservoir volume and the spillway crest length. Consequently, an additional bivariate return period, the so-called routed return period, was defined in terms of risk of dam overtopping based on this maximum water elevation obtained after routing the inflow hydrographs. The theoretical return periods, which give the probability of occurrence of a hydrograph prior to accounting for the reservoir routing, were compared with the routed return period, as in both cases hydrographs with the same probability will draw a curve in the peak-volume space. The procedure was applied to the case study of the Santillana reservoir in Spain. Different reservoir volumes and spillway lengths were considered to investigate the influence of the dam and reservoir characteristics on the results. The methodology improves the estimation of the Design Flood Hydrograph and can be applied to assess the risk of dam overtoppin

    La reinvención de la autenticidad en el contexto de la mercantilización neoliberal

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    Desde la últimas décadas del siglo pasado, la constatación empírica de que los límites naturales al crecimiento estaban siendo traspasados (García, 2004) supuso un incremento de la conciencia medioambiental y dio lugar a la búsqueda de respuestas de distinto tipo. El concepto de 'Parque Natural', como un intento de preservar determinados espacios, se inscribe en este contexto. En su versión neoliberal dicha preservación no implica ninguna modificación sustantiva de las reglas que impone el desarrollo económico capitalista. De este modo, se convierte en una aplicación del binomio 'desarrollo sostenible', un oxímoron (Latouche, 2006) donde se yuxtaponen dos significados contrapuestos, a saber, desarrollo económico capitalista y sostenibilidad medioambiental

    Chemical Features in the Circumnuclear Disk of the Galactic Center

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    The circumnuclear disk (CND) of the Galactic Center is exposed to many energetic phenomena coming from the supermassive black hole Sgr A* and stellar activities. These energetic activities can affect the chemical composition in the CND by the interaction with UV-photons, cosmic-rays, X-rays, and shock waves. We aim to constrain the physical conditions present in the CND by chemical modeling of observed molecular species detected towards it. We analyzed a selected set of molecular line data taken toward a position in the southwest lobe of the CND with the IRAM 30m and APEX 12-meter telescopes and derived the column density of each molecule using a large velocity gradient (LVG) analysis. The determined chemical composition is compared with a time-dependent gas-grain chemical model based on the UCL\_CHEM code that includes the effects of shock waves with varying physical parameters. Molecules such as CO, HCN, HCO+^+, HNC, CS, SO, SiO, NO, CN, H2_2CO, HC3_3N, N2_2H+^+ and H3_3O+^+ are detected and their column densities are obtained. Total hydrogen densities obtained from LVG analysis range between 2×1042 \times 10^4 and 1×1061 \times 10^6\,cm3^{-3} and most species indicate values around several ×105\times 10^5\,cm3^{-3}, which are lower than values corresponding to the Roche limit, which shows that the CND is tidally unstable. The chemical models show good agreement with the observations in cases where the density is 104\sim10^4\,cm3^{-3}, the cosmic-ray ionization rate is high, >1015>10^{-15} \,s1^{-1}, or shocks with velocities >40> 40\,km s1^{-1} have occurred. Comparison of models and observations favors a scenario where the cosmic-ray ionization rate in the CND is high, but precise effects of other factors such as shocks, density structures, UV-photons and X-rays from the Sgr A* must be examined with higher spatial resolution data.Comment: 17 Pages, 13 figures, accepted for publication in A&

    Complex organic molecules in the Galactic Centre: the N-bearing family

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    We present an unbiased spectral line survey toward the Galactic Centre (GC) quiescent giant molecular cloud (QGMC), G+0.693 using the GBT and IRAM 30\, telescopes. Our study highlights an extremely rich organic inventory of abundant amounts of nitrogen (N)-bearing species in a source without signatures of star formation. We report the detection of 17 N-bearing species in this source, of which 8 are complex organic molecules (COMs). A comparison of the derived abundances relative to H2_2 is made across various galactic and extragalactic environments. We conclude that the unique chemistry in this source is likely to be dominated by low-velocity shocks with X-rays/cosmic rays also playing an important role in the chemistry. Like previous findings obtained for O-bearing molecules, our results for N-bearing species suggest a more efficient hydrogenation of these species on dust grains in G+0.693 than in hot cores in the Galactic disk, as a consequence of the low dust temperatures coupled with energetic processing by X-ray/cosmic ray radiation in the GC.Comment: 24 pages, 23 figures, 7 tables, accepted for publication in MNRA

    Walking Through Cantor's Paradise and Escher's Garden: Epistemological Reflections on the Mathematical Infinite (II)

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    Infinity is not an easy concept. A number of difficulties that people cope with when dealing with problems related to infinity include its abstract nature, understanding infinity as an ongoing, never ending process, understanding infinity as a set of an infinite number of elements and appreciating well-known paradoxes. Infinity can be understood in several ways with often incompatible meanings, and can involve value judgments or assumptions that are neither explicit nor desired. To usher in its definition, we distinguish several aspects, teleological, artistic (Escher); some definitive, some potential, and others actual. This article also deals with some still unresolved aspects of the concept of infinity

    Tracing shocks and photodissociation in the Galactic center region

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    We present a systematic study of the HNCO, C18O, 13CS, and C34S emission towards 13 selected molecular clouds in the Galactic center region. The molecular emission in these positions are used as templates of the different physical and chemical processes claimed to be dominant in the circumnuclear molecular gas of galaxies. The relative abundance of HNCO shows a variation of more than a factor of 20 amo ng the observed sources. The HNCO/13CS abundance ratio is highly contrasted (up to a factor of 30) between the shielded molecular clouds mostly affected by shocks, where HNCO is released to gas-phase from grain mantles, and those pervaded by an intense UV radiation field, where HNCO is photo-dissociated and CS production favored via ion reactions. We propose the relative HNCO to CS abundance ratio as a highly contrasted diagnostic tool to distinguish between the influence of shocks and/or the radiation field in the nuclear regions of galaxies and their relation to the evolutionary state of their nuclear star formation bursts.Comment: 25 pages, 5 figures, Accepted for publication in Ap
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