X-Shooter observations of low-mass stars in the Eta Chamaeleontis association

The nearby Eta Chamaeleontis association is a collection of 4-10 Myr old stars with a disk fraction of 35-45%. In this study, the broad wavelength coverage of VLT/X-Shooter is used to measure the stellar and mass accretion properties of 15 low mass stars in the Eta Chamaeleontis association. For each star, the observed spectrum is fitted with a non-accreting stellar template and an accretion spectrum obtained from assuming a plane-parallel hydrogen slab. Five of the eight stars with an IR disk excess show excess UV emission, indicating ongoing accretion. The accretion rates measured here are similar to those obtained from previous measurements of excess UV emission, but tend to be higher than past measurements from H-alpha modeling. The mass accretion rates are consistent with those of other young star forming regions.Comment: Accepted for publication in Astronomy & Astrophysic

Spiel, Sprache und die intrinsische Natur von Welt und Wirkung

Eine Wissenschaft ist ein funktionales System gegenseitig abhängiger Größen, das intrinsischer Träger bedarf. Für basale Größen bedarf es absolut intrinsischer Träger. Das lässt sich etwa am Schachspiel erläutern. Eine hierarchisch aufgebaute Welt mit kausal interagierenden Dingen, wie sie Gregg Rosenberg konzipiert, braucht ein komplexes Trägergeflecht. Es entspricht dem Aufbau einer Sprache. Im Vergleich mit einem hylemorphistischen Weltbild wird eine Trägerontologie genauer entfaltet

Solving the stellar 62Ni problem with AMS

An accurate knowledge of the neutron capture cross sections of 62,63Ni is crucial since both isotopes take key positions which affect the whole reaction flow in the weak s process up to A=90. No experimental value for the 63Ni(n,gamma) cross section exists so far, and until recently the experimental values for 62Ni(n,gamma) at stellar temperatures (kT=30 keV) ranged between 12 and 37 mb. This latter discrepancy could now be solved by two activations with following AMS using the GAMS setup at the Munich tandem accelerator which are also in perfect agreement with a recent time-of-flight measurement. The resulting (preliminary) Maxwellian cross section at kT=30 keV was determined to be 30keV = 23.4 +/- 4.6 mb. Additionally, we have measured the 64Ni(gamma,n)63Ni cross section close to threshold. Photoactivations at 13.5 MeV, 11.4 MeV and 10.3 MeV were carried out with the ELBE accelerator at Forschungszentrum Dresden-Rossendorf. A first AMS measurement of the sample activated at 13.5 MeV revealed a cross section smaller by more than a factor of 2 compared to NON-SMOKER predictions.Comment: Proceedings of the 11th International Conference on Accelerator Mass Spectrometry in Rome, Sept. 14-19, 2008; to be published in Nucl. Instr. Meth.

Detection of leaf structures in close-range hyperspectral images using morphological fusion

Close-range hyperspectral images are a promising source of information in plant biology, in particular, for in vivo study of physiological changes. In this study, we investigate how data fusion can improve the detection of leaf elements by combining pixel reflectance and morphological information. The detection of image regions associated to the leaf structures is the first step toward quantitative analysis on the physical effects that genetic manipulation, disease infections, and environmental conditions have in plants. We tested our fusion approach on Musa acuminata (banana) leaf images and compared its discriminant capability to similar techniques used in remote sensing. Experimental results demonstrate the efficiency of our fusion approach, with significant improvements over some conventional methods

La difícil autonomía de José Luis Cebrián como director del Diario ABC, 1975-1977

La breve dirección de José Luis Cebrián en ABC (febrero 1975-octubre 1977) coincidió con el final del tardofranquismo, los comienzos de la transición y una incipiente crisis en el diario. Tras su controvertida designación, fue relegado a funciones meramente periodísticas mientras el control ideológico-político del diario continuó en las manos de Torcuato Luca de Tena. El supuesto fracaso de Cebrián, hombre más bien apolítico, se debió en buena medida a razones empresariales y políticas externas a él dado que ABC adoptó una orientación confusa y extremadamente conservadora, como se refleja en unas normas entregadas al director que se publican por vez primera.The short period of José Luis Cebrián as editor of ABC (February 1975-October 1977) coincided with the end of Franco’s dictatorship, the beginnings of the transition to democracy, and an incipient crisis in the newspaper. After his controversial appointment, he was entrusted to run the newsroom while the ideological and political control continued in the hands of the former editor Torcuato Luca de Tena. The alleged failure of a rather apolitical man like Cebrián was greatly due to business and political reasons external to him because ABC adopted extremely conservative positions, as an until now unpublished document delivered to the editor proves

Ascl3 marks adult progenitor cells of the mouse salivary gland

AbstractThe Ascl3 transcription factor marks a subset of salivary gland duct cells present in the three major salivary glands of the mouse. In vivo, these cells generate both duct and secretory acinar cell descendants. Here, we have analyzed whether Ascl3-expressing cells retain this multipotent lineage potential in adult glands. Cells isolated from mouse salivary glands were cultured in vitro as non-adherent spheres. Lineage tracing of the Ascl3-expressing cells within the spheres demonstrates that Ascl3+ cells isolated from adult glands remain multipotent, generating both duct and acinar cell types in vitro. Furthermore, we demonstrate that the progenitor cells characterized by Keratin 5 expression are an independent population from Ascl3+ progenitor cells. We conclude that the Ascl3+ cells are intermediate lineage-restricted progenitor cells of the adult salivary glands

Análisis de la instalación y operación de los equipos del sistema automatizado de las estaciones de bombeo del oleoducto transecuatoriano

El presente trabajo tiene como objetivo realizar el análisis del montaje industrial del sistema automatizado de las estaciones de bombeo del oleoducto transecuatoriano, partiendo del estudio de las necesidades operacionales de las unidades, de los métodos de instalación y criterios constructivos, y de la selección de equipos. La correcta ejecución de un proyecto de esta magnitud depende en gran medida de la gestión realizada planificando las actividades de campo, definiendo todas y cada una de las actividades a realizarse en el montaje, organizando los recursos disponibles, y sobre todo una excelente dirección y control del proyecto. Siempre optimizando los costos del montaje: los costos directos como mano de obra, el gasto en equipos y materiales; y los costos indirectos de administración, gastos de obra y gastos generales

Highly Sensitive Gamma-Spectrometers of GERDA for Material Screening: Part 2

The previous article about material screening for GERDA points out the importance of strict material screening and selection for radioimpurities as a key to meet the aspired background levels of the GERDA experiment. This is directly done using low-level gamma-spectroscopy. In order to provide sufficient selective power in the mBq/kg range and below, the employed gamma-spectrometers themselves have to meet strict material requirements, and make use of an elaborate shielding system. This article gives an account of the setup of two such spectrometers. Corrado is located in a depth of 15 m w.e. at the MPI-K in Heidelberg (Germany), GeMPI III is situated at the Gran-Sasso underground laboratory at 3500 m w.e. (Italy). The latter one aims at detecting sample activities of the order ~0.01 mBq/kg, which is the current state-of-the-art level. The applied techniques to meet the respective needs are discussed and demonstrated by experimental results.Comment: Featured in: Proceedings of the XIV International Baksan School "Particles and Cosmology" Baksan Valley, Kabardino-Balkaria, Russia, April 16-21,2007. INR RAS, Moscow 2008. ISBN 978-5-94274-055-9, pp. 233-238; (6 pages, 4 figures

The Search for Supernova-produced Radionuclides in Terrestrial Deep-sea Archives

An enhanced concentration of 60Fe was found in a deep ocean's crust in 2004 in a layer corresponding to an age of ~2 Myr. The confirmation of this signal in terrestrial archives as supernova-induced and detection of other supernova-produced radionuclides is of great interest. We have identified two suitable marine sediment cores from the South Australian Basin and estimated the intensity of a possible signal of the supernova-produced radionuclides 26Al, 53Mn, 60Fe and the pure r-process element 244Pu in these cores. A finding of these radionuclides in a sediment core might allow to improve the time resolution of the signal and thus to link the signal to a supernova event in the solar vicinity ~2 Myr ago. Furthermore, it gives an insight on nucleosynthesis scenarios in massive stars, the condensation into dust grains and transport mechanisms from the supernova shell into the solar system