Discovery of kilogauss magnetic fields in three DA white dwarfs

We have detected longitudinal magnetic fields between 2 and 4 kG in three (WD 0446$-$790, WD 1105$-$048, WD 2359$-$434) out of a sample of 12 normal DA white dwarfs by using optical spectropolarimetry done with the VLT Antu 8 m telescope equipped with FORS1. With the exception of 40 Eri B (4 kG) these are the first positive detections of magnetic fields in white dwarfs below 30 kG. Although suspected, it was not clear whether a significant fraction of white dwarfs contain magnetic fields at this level. These fields may be explained as fossil relics from magnetic fields in the main-sequence progenitors considerably enhanced by magnetic flux conservation during the shrinkage of the core. A detection rate of 25 % (3/12) may indicate now for the first time that a substantial fraction of white dwarfs have a weak magnetic field. This result, if confirmed by future observations, would form a cornerstone for our understanding on the evolution of stellar magnetic fields. Keywords: stars: white dwarfs - stars: magnetic fields - stars: individual: WD0446-790, WD1105-048, WD2359-434Comment: 15 pages, 7 figures, Astronomy and Astrophysics, in pres

El aplazamiento «ad tempus» de la prole en el consentimiento matrimonial.

Material incluido en el volumen especial de la revista del Instituto Martín de Azpilcueta, Universidad de Navarra : Ius Canonicum (1999), en honor de Javier Hervada

Gender comparisons in mother-child emotion talk: A meta-analysis

Mother-child emotion talk is one of the main ways through which children learn about emotions. Some previous research studies have suggested that mother-child emotion talk is a gendered process, influencing how girls and boys talk about emotions. Despite inconsistent findings in establishing if mothers use different amounts of emotion talk with their daughters and sons, there is no known meta-analysis of the literature examining gender differences in the frequency of mother-child emotion talk. The aim of this comprehensive meta-analysis is to explore gender comparisons in the frequency of mother-child emotion talk as well as the moderators of these differences. Based on 34 independent group samples (samples of unique individuals) consisting of 3649 participants, no gender differences in the frequency of emotion talk between mothers of daughters and mothers of sons were found. Using a random-effects model, the meta-analysis had a mean weighted effect size of Cohen’s d = .04 (95% CI = [−.05, .13], p = .36). It was not heterogeneous, Qw (33) = 39.36, p = .21. Thus, findings of the present meta-analysis suggest that mother-child emotion talk has not been shown to be gendered, which has implications for children’s socialization of emotions

Comportamiento Biológico de Aloinjertos Tendinosos Intraarticulares.

En el presente trabajo, los autores han efectuado un estudio experimental de la respuesta biológica de aloinjertos tendinosos, implantados en el interior de la articulación de la rodilla. Se ha seguido mediante microscopía óptica y micoscopía electrónica, la revascularización de los implantes y los cambios tendinosos intrínsecos, tanto en la serie de aloinjertos en "fresco", como de aloinjertos congelados. En los aloinjertos en fresco, predomina la intensa respuesta inflamatoria -inmunitaria, siendo la respuesta reparadora de escasos signos de orientación del tejido fibroso definitivo. En la serie de injertos congelados, los fenómenos inflamatorios son escasos, predominando la angiogénesis.In this paper, the authors have studied the biological respons e of tendinous allografts, implanted inside the kne e articulation, in a experimental study. The revascularization of the grafts, and the intrinsic tendinous change s in both series, frozen and no frozen allografts, is studied with optical and electron microscopy. In the no frozen allografts, is more important the intensive inflamatory inmunitary response, with few signs of orientation of the definitive fibrous tissue. In the serie of frozen allografts, the inflamatory response is limited with predominanc e of the angiogénesis process

Liquid phase epitaxy and optical investigation of KYb(WO4)2 thin layers

In recent years, Yb3+ has attracted much attention as an activating ion because of its small quantum defect for laser emission from 2F5/2 to 2F7/2 at ~1.03 µm [1], which provides high efficiency and reduced heat generation. Of high practical interest is the thin-disk laser concept [2], which possesses a tremendous advantage over rod lasers because of its axial-cooling approach and consequent weak thermal lensing and good beam quality.\ud A promising material for Yb3+ thin-disk lasers is KYb(WO4)2 (KYbW) [3]. It can be grown from high-temperature solutions [4]. Nevertheless, the growth of high-quality, single-crystalline layers with thickness in the range of the absorption length of ~13 µm at 981 nm has as yet not been reported. A suitable substrate material is KY(WO4)2 (KYW), but the relatively large differences in the thermal expansion coefficients between KYW and KYbW along the [100], [001], and especially [010] directions [5] favor low temperatures for the hetero-epitaxial growth.\ud For the first time, we demonstrate liquid phase epitaxy (LPE) of KYbW layers. The layers were grown at start temperatures as low as 520°C, which is favorable in order to decrease the thermal stresses due to the differences in the thermal expansion coefficients of substrate and layer. Moreover, the choice of [010]-oriented substrates bypasses the large difference in the thermal expansion coefficient along the [010] direction. KY1-xYbx(WO4)2 layers with varying x = 0.03-1.00 were grown by LPE. The chloride solvent consisted of the eutectic composition [6] 24.4 mol.% KCl, 30.4 mol.% NaCl, and 42.2 mol.% CsCl. The growth temperature spanned the range from 580 to 500°C and the cooling rate was 0.67-1.00 Kh-1. Crack-free, transparent KYbW layers were grown on (010) substrates.\ud Spectroscopic investigations have shown that the lifetime of ~250 µs measured in our LPE-grown KYbW layers is dominated by radiative decay and is very similar to that measured in top-seeded-solution-grown bulk samples [4]. Fast energy migration among the Yb3+ ions and energy transfer to small amounts of Tm3+ and Er3+ ions present in the YbCl3 reagent lead to visible upconversion luminescence in the layers under 981-nm excitation.\ud \ud [1] T.Y. Fan, IEEE J. Quantum Electron. 29, 1457 (1993).\ud [2] A. Giesen, H. Hügel, A. Voss, K. Wittig, U. Brauch, H. Opower, Appl. Phys. B 58, 365 (1994).\ud [3] P. Klopp, U. Griebner, V. Petrov, X. Mateos, M.A. Bursukova, M.C. Pujol, R. Solé, J. Gavaldà, M. Aguiló, F. Güell, J. Massons, T. Kirilov, F. Díaz, Appl. Phys. B 74, 185 (2002).\ud [4] M.C. Pujol, M.A. Bursukova, F. Güell, X. Mateos, R. Solé, J. Gavaldà, M. Aguiló, J. Massons, F. Díaz, P. Klopp, U. Griebner, V. Petrov, Phys. Rev. B 65, 165121 (2002).\ud [5] M.C. Pujol, X. Mateos, R. Solé, J. Massons, J. Gavaldà, F. Díaz, M. Aguiló, Mater. Sci. Forum 378-381, 710 (2001).\ud [6] D. Ehrentraut, M. Pollnau, S. Kück, Appl. Phys. B 75, 59 (2002)

Open Data for Public Administration: Exploitation and semantic organization of institutional web content

The project presented has been financed by Government of Aragon and is part of the ''Open Data'' initiative promoted by that organization. Given the amount of unstructured information related to the Government of Aragon currently published on the Internet, with slightly or no standardization and decentralized, it emerges the need to gather it systematically to be offered to all interested collectives from a single access point in a public and structured way. Within this context, ''Aragon Open Data'' project aims to collect, organize, store and maintain updated, Administration''s web information by means of human language and semantic technologies. Firstly, crawling is performed over websites in order to retrieve textual data over which Natural Language Processing (NLP) and ontology-based techniques are applied. Thereafter, results are stored into NoSQL databases, allowing future open access and simple data exploitation. NLP techniques used in the project involve named-entities recognition and classification (NERC) and texts semantic classification and summarization

Liquid phase epitaxy and spectroscopic investigation of optically active KYb(WO4)2 thin layers

In recent years, Yb3+ has attracted much attention as an activating ion because of its small quantum defect for laser emission from 2F5/2 to 2F7/2 at ~1.03 µm, which provides high efficiency and reduced heat generation. A promising material for Yb3+ lasers is KYb(WO4)2 (KYbW) [1]. It can be grown from high-temperature solutions [2]. A suitable substrate material for the growth of single-crystalline layers with thicknesses in the range of the absorption length of ~13 µm at 981 nm is KY(WO4)2 (KYW).\ud We demonstrate the liquid phase epitaxy (LPE) of KYbW layers at start temperatures as low as 520°C from the chloride solvent KCl-NaCl-CsCl. This temperature is favorable in order to decrease the thermal stresses due to the differences in the thermal expansion coefficients of substrate and layer. Moreover, the choice of [010]-oriented KYW substrates bypasses the large difference in the thermal expansion coefficient along the [010] direction. Our spectroscopic investigations show that the fluorescence lifetime of ~250 µs measured in our LPE-grown KYbW layers is dominated by radiative decay and is very similar to that measured in top-seeded-solution-grown bulk samples [2]. Fast energy migration among the Yb3+ ions and energy transfer to small amounts of Tm3+ and Er3+ ions present in the YbCl3 reagent lead to visible upconversion luminescence in the layers under 981-nm excitation.\ud \ud [1] P. Klopp, U. Griebner, V. Petrov, X. Mateos, M.A. Bursukova, M.C. Pujol, R. Solé, J. Gavaldà, M. Aguiló, F. Güell, J. Massons, T. Kirilov, F. Díaz, Appl. Phys. B 2002, 74, 185\ud [2] M.C. Pujol, M.A. Bursukova, F. Güell, X. Mateos, R. Solé, J. Gavaldà, M. Aguiló, J. Massons, F. Díaz, P. Klopp, U. Griebner, V. Petrov, Phys. Rev. B 2002, 65, 16512