Diffuse interstellar bands in fullerene planetary nebulae: the fullerenes - diffuse interstellar bands connection

We present high-resolution (R~15000) VLT/UVES optical spectra of two planetary nebulae (PNe; Tc 1 and M 1-20) where C60 (and C70) fullerenes have already been found. These spectra are of high-quality (S/N > 300) for PN Tc 1, which permits us to search for the expected electronic transitions of neutral C60 and diffuse interstellar bands (DIBs). Surprisingly, we report the non-detection of the most intense optical bands of C60 in Tc 1, although this could be explained by the low C60 column density estimated from the C60 infrared bands if the C60 emission peaks far away from the central star. The strongest and most common DIBs in both fullerene PNe are normal for their reddening. Interestingly, the very broad 4428 A DIB and the weaker 6309 A DIB are found to be unusually intense in Tc 1. We also report the detection of a new broad (FWHM~5 A) unidentified band at ~6525 A. We propose that the 4428 A DIB (probably also the 6309 A DIB and the new 6525 A band) may be related to the presence of larger fullerenes (e.g., C80, C240, C320, and C540) and buckyonions (multishell fullerenes such as C60@C240 and C60@C240@C540) in the circumstellar envelope of Tc 1.Comment: Accepted for publication in Astronomy & Astrophysics Letters (6 pages, 4 figures, and 1 Table

Celtic Place- and Personal-names in Spain and the Socio-political Structure and Evolution of the Celtiberians

In this paper two Celtiberian place- and personal-names are examined: Moericus, the name of a Celtiberian war chief in the Second Punic War, and Complega, a town founded by Celtiberian mavericks and conquerd by praetor Fulvius Flaccus in 182 B.C. This indicates that two very important political and social institutions of the La Tène Celts are documented in Celtiberian Spain at an early date: the armed retinue that accompanied a chief with a name ended in –rix, and the armed mercenary bands that migrated long distances to conquer land and found new townships

A search for diffuse bands in fullerene planetary nebulae: evidence of diffuse circumstellar bands

Large fullerenes and fullerene-based molecules have been proposed as carriers of diffuse interstellar bands (DIBs). The recent detection of the most common fullerenes (C60 and C70) around some planetary nebulae (PNe) now enable us to study the DIBs towards fullerene-rich space environments. We search DIBs in the optical spectra towards three fullerene-containing PNe (Tc 1, M 1-20, and IC 418). Special attention is given to DIBs which are found to be unusually intense towards these fullerene sources. In particular, an unusually strong 4428A absorption feature is a common charateristic of fullerene PNe. Similar to Tc 1, the strongest optical bands of neutral C60 are not detected towards IC 418. Our high-quality (S/N > 300) spectra for PN Tc 1, together with its large radial velocity, permit us to search for the presence of diffuse bands of circumstellar origin, which we refer to as diffuse circumstellar bands (DCBs). We report the first tentative detection of two DCBs at 4428 and 5780 A in the fullerene-rich circumstellar environment around the PN Tc 1. Laboratory and theoretical studies of fullerenes in their multifarious manifestations (carbon onions, fullerene clusters, or even complex species formed by fullerenes and other molecules like PAHs or metals) may help solve the mystery of some of the diffuse band carriers.Comment: Accepted for publication in Astronomy & Astrophysics (16 pages, 10 figures, and 7 Tables); final version (changes regarding PN M 1-20 and language corrected

Non-linear response of single-molecule magnets: field-tuned quantum-to-classical crossovers

Quantum nanomagnets can show a field dependence of the relaxation time very different from their classical counterparts, due to resonant tunneling via excited states (near the anisotropy barrier top). The relaxation time then shows minima at the resonant fields H_{n}=n D at which the levels at both sides of the barrier become degenerate (D is the anisotropy constant). We showed that in Mn12, near zero field, this yields a contribution to the nonlinear susceptibility that makes it qualitatively different from the classical curves [Phys. Rev. B 72, 224433 (2005)]. Here we extend the experimental study to finite dc fields showing how the bias can trigger the system to display those quantum nonlinear responses, near the resonant fields, while recovering an classical-like behaviour for fields between them. The analysis of the experiments is done with heuristic expressions derived from simple balance equations and calculations with a Pauli-type quantum master equation.Comment: 4 pages, 3 figures. Submitted to Phys. Rev. B, brief report

Inteligencia competitiva y definición de una estrategia para la comercialización del cacao de la variedad arriba

Esta tesis está basada en el diseño de una estrategia de comercialización del cacao variedad "arriba o nacional", el cual es identificado como un cacao fino y de aroma. En este estudio, hacemos un análisis de la oferta de cacao fino y de aroma descubriendo a Indonesia y Ecuador como uno de los mayores productores de cacao fino y de aroma. También hemos estudiado la demanda, que está compuesta por algunos países especialmente europeos, ya que éstos son los mayores productores de chocolate fino del mundo. Así hemos identificado el mercado al cual nos dirigimos a través del análisis de la demanda mundial. El Ecuador se encuentra ante una serie de ventajas agroclimáticas, de trayectoria y, de posicionamiento muy buenas que permitirían al país incrementar los niveles de exportaciones de este tipo de cacao. Así mismo, se encuentra ante una serie de desventajas culturales, tecnológicas y de infraestructura que no permiten desarrollar el sector cacaotero interno lo cual se convierte en una amenaza que nos perjudicaría en el comercio internacional del cacao Dadas estas condiciones, se propone una estrategia formada de tres fases, la primera, es la renovación de un cuarto de las plantaciones actuales. La segunda fase, está dirigida a los compradores del cacao fino y de aroma y la tercera está dirigida al consumidor de chocolate que será quien exija cacao del Ecuador para el chocolate que consuma