Carbon and oxygen in HII regions of the Magellanic Clouds: abundance discrepancy and chemical evolution

We present C and O abundances in the Magellanic Clouds derived from deep spectra of HII regions. The data have been taken with the Ultraviolet-Visual Echelle Spectrograph at the 8.2-m VLT. The sample comprises 5 HII regions in the Large Magellanic Cloud (LMC) and 4 in the Small Magellanic Cloud (SMC). We measure pure recombination lines (RLs) of CII and OII in all the objects, permitting to derive the abundance discrepancy factors (ADFs) for O^2+, as well as their O/H, C/H and C/O ratios. We compare the ADFs with those of other HII regions in different galaxies. The results suggest a possible metallicity dependence of the ADF for the low-metallicity objects, but more uncertain for high-metallicity objects. We compare nebular and B-type stellar abundances and we find that the stellar abundances agree better with the nebular ones derived from collisionally excited lines (CELs). Comparing these results with other galaxies we observe that stellar abundances seem to agree better with the nebular ones derived from CELs in low-metallicity environments and from RLs in high-metallicity environments. The C/H, O/H and C/O ratios show almost flat radial gradients, in contrast with the spiral galaxies where such gradients are negative. We explore the chemical evolution analysing C/O vs. O/H and comparing with the results of HII regions in other galaxies. The LMC seems to show a similar chemical evolution to the external zones of small spiral galaxies and the SMC behaves as a typical star-forming dwarf galaxy.Comment: Accepted for publication in MNRAS, 17 pages, 11 figures, 8 table

Model-driven Test Engineering: A Practical Analysis in the AQUA-WS Project

The effective application of test phases has been one of the most relevant, critical and cost phases in the life cycle of software projects in the last years. During the test phase, the test team has to assure the quality of the system and the concordance with the initial requirements of the system. The model driven paradigm is offering suitable results in some areas and the test phase could be one of them. This paper presents how the application of this paradigm can help to improve this aspect in the functional test generation and it analyses the experience in a real project developed under this approach.Ministerio de Ciencia e Innovación TIN2010-20057-C03-02Ministerio de Ciencia e Innovación TIN 2010-12312-EJunta de Andalucía TIC-578

Modelización de las inestabilidades en la deformación plástica de monocristales de circona estabilizada con itria (YCSZ)

En este trabajo se presenta un modelo para explicar las inestabilidades dinámicas observadas durante la deformación plástica a alta temperatura de monocristales de circona estabilizada con itria, (YCSZ, yttria cubic stabilized zirconia) con alto contenido en itria. El modelo se basa en el fenómeno Portevin-Le Chatelier (PLC), que consiste en episodios sucesivos de anclaje y desanclaje de dislocaciones cuando éstas se mueven con una velocidad del mismo orden que los defectos que obstaculizan su movimiento. La evaluación numérica de los parámetros implicados en el modelo muestra que las inestabilidades plásticas son totalmente compatibles con el efecto Portevin- Le Chatelie

Estudio de la difusividad del agua en el secado de alginato de sodio en charolas

Con el objetivo de reducir el contenido de humedad del alginato de sodio a un nivel recomendable y sin dañar el producto, se realizó un estudio del secado de este material en charolas. Experimentalmente se analizó la cinética del proceso utilizando diferentes condiciones de operación para determinar las curvas de secado y la velocidad de la pérdida de humedad del material.Por la viscosidad del alginato de sodio y sus limitaciones para alcanzar el contenido de humedad en equilibrio, se desarrolló un modelo para predecir el comportamiento del secado en la última etapa del proceso. El modelo se basó en la transferencia de masa del agua contenida en el material en función del tiempo de deshidratación en el estado inestable y del espacio recorridoa través del espesor de la muestra para el estado estable.Se consideró que la resistencia al transporte de masa de agua a través del espesor del material fue superior a la de la capa límite del gas secante, por tanto se supuso que el mecanismo de difusión es el que rige el proceso de secado del alginato de sodio

(−)-Istanbulin A

The title compound (systematic name: 9a-hydr­oxy-3,4a,5-trimethyl-4a,6,7,8a,9,9a-hexa­hydro-4H,5H-naphtho[2,3-b]furan-2,8-dione), C15H20O4, is a sesquiterpene lactone showing the typical eremophilanolide skeleton, which has been isolated from the plant Senecio candidans collected in the Chilean Magallanes region. The present study confirms the atomic connectivity assigned on the basis of 1H and 13C NMR spectroscopy, as well as the relative stereochemistry of the 4α-methyl,5α-methyl,8β-hydr­oxy,10β-H unit. The crystal structure is stabilized by inter­molecular O—H⋯O hydrogen bonds involving the hydr­oxy group as donor and the oxo group as acceptor, giving chains along the a axis. The absolute structure was not determined because of the lack of suitable anomalous scatters

Potencial utilización de la termografía infrarroja para la lectura de la IDTB en cabras

En este trabajo se pretende estudiar la potencial utilización de la TI (Termografía infrarroja) en la lectura de la IDTB (intradermotuberculinización) en cabras. El análisis de las temperaturas mostró un aumento significativo a las 24h postinoculación de la tuberculina en el conjunto de los individuos, no observándose influencia significativa de la capa de los animales sobre las temperaturas. La comparación de los resultados de ambas técnicas no evidenció asociación significativa.The aim of this experiment is to study the potential use of IT (infrared termography) for measurement of PPD (Purified protein derivate) test in goats. The study of the temperatures showed a significant increase at 24hours post-inoculation of the PPD in the set of all the individuals, not being observed significant influence of the colour of the animals on the temperatures. The comparison of the results from the PPD skin test, and IT did not demonstrate significant association

Bloch oscillations in an aperiodic one-dimensional potential

We study the dynamics of an electron subjected to a static uniform electric field within a one-dimensional tight-binding model with a slowly varying aperiodic potential. The unbiased model is known to support phases of localized and extended one-electron states separated by two mobility edges. We show that the electric field promotes sustained Bloch oscillations of an initial Gaussian wave packet whose amplitude reflects the band width of extended states. The frequency of these oscillations exhibit unique features, such as a sensitivity to the initial wave packet position and a multimode structure for weak fields, originating from the characteristics of the underlying aperiodic potential.Comment: 6 pages, 7 figure

Spanish onshore sampling of Lepidorhombus spp.

Working document presented in WGCATCH.Results of Lepidorhombus spp. from the Spanish onshore sampling programme under the Data Collection Framework (2009-2014) are presented. Sampling covers two species (Lepidorhombus whiffiagonis and Lepidorhombus boscii) in ICES Subarea VI, VII, Divisions VIIIabd and Divisions VIIIc-IXa. Fishery description shows the importance of five métiers for these species and the relevance of a small group of ports. A description of the sampling level, sampling design and sampling procedures in relation to landing practices are presented, as well as a brief discussion about further developments to improve the sampling