Mineralogical analysis of ceramic tiles by FTIR: A quantitative attempt

A method for quantitative mineralogical analysis by ATR-FTIR has been developed. The method relies on the use of the main band of calcite as a reference for the normalization of the IR spectrum of a mineral sample. In this way, the molar absorptivity coefficient in the Lambert–Beer law and the components of a mixture in mole percentage can be calculated. The GAMS equation modeling environment and the NLP solver CONOPT (©ARKI Consulting and Development) were used to correlate the experimental data in the samples considered. Mixtures of different minerals and gypsum were used in order to measure the minimum band intensity that must be considered for calculations and the detection limit. Accordingly, bands of intensity lower than 0.01 were discarded. The detection limit for gypsum was about 7% (mol/total mole). Good agreement was obtained when this FTIR method was applied to ceramic tiles previously analyzed by X-ray diffraction (XRD) or mineral mixtures prepared in the lab.

La cobertura periodística de la obesidad en la prensa española (2000-2005)

Antecedentes: la obesidad es un problema de salud pública en España. Los medios de comunicación son una herramienta útil para la salud pública. Objetivo: explorar el tratamiento periodístico de la obesidad en la prensa escrita española durante 2000-2005, frecuencia de aparición, fuentes de información y enfoques, en relación con el contexto social. Materiales y métodos: análisis de contenido cuantitativo de 690 noticias publicadas en El País, El Mundo y ABC. Cálculo de frecuencias y odds ratio (OR) con intervalos de confianza (IC) del 95% y significación estadística. Resultados: incrementaron las noticias de 2000 (n=25) a 2005 (n=185). Se centraron en denuncias (36,4%) y magnitud del problema (15,7%), en detrimento de aquellas sobre iniciativas-estrategias políticas (3,8%). Destacan los hombres como fuentes informativas principales (75,5%) y las mujeres como primeras firmantes de las noticias (56,1%). Los hombres del ámbito médico-sanitario (OR=1,98;IC95%,1,11-3,57) y las mujeres del ámbito político (OR=2,54;IC95%1,46-4,42) tienen mayor probabilidad de ser la fuente informativa principal. Conclusiones: la cobertura periodística de la obesidad durante 2000-2005 aumentó, coincidiendo con el desarrollo de respuestas políticas en torno al tema. Principalmente, se denuncia el problema. Destaca la escasa cobertura periodística de iniciativas-estrategias políticas, sugiriendo incipiente interacción entre la agenda política y mediática.

Orbital and Physical Properties of the σ Ori Aa, Ab, B Triple System

We provide a complete characterization of the astrophysical properties of the σ Ori Aa, Ab, B hierarchical triple system and an improved set of orbital parameters for the highly eccentric σ Ori Aa, Ab spectroscopic binary. We compiled a spectroscopic data set comprising 90 high-resolution spectra covering a total time span of 1963 days. We applied the Lehman-Filhés method for a detailed orbital analysis of the radial velocity curves and performed a combined quantitative spectroscopic analysis of the σ Ori Aa, Ab, B system by means of the stellar atmosphere code FASTWIND. We used our own plus other available information on photometry and distance to the system for measuring the radii, luminosities, and spectroscopic masses of the three components. We also inferred evolutionary masses and stellar ages using the Bayesian code BONNSAI. The orbital analysis of the new radial velocity curves led to a very accurate orbital solution of the σ Ori Aa, Ab pair. We provided indirect arguments indicating that σ Ori B is a fast-rotating early B dwarf. The FASTWIND+BONNSAI analysis showed that the Aa, Ab pair contains the hottest and most massive components of the triple system while σ Ori B is a bit cooler and less massive. The derived stellar ages of the inner pair are intriguingly younger than the one widely accepted for the σ Orionis cluster, at 3 ± 1 Ma. The outcome of this study will be of key importance for a precise determination of the distance to the σ Orionis cluster, the interpretation of the strong X-ray emission detected for σ Ori Aa, Ab, B, and the investigation of the formation and evolution of multiple massive stellar systems and substellar objects.