Estratigrafía del Cretácico Superior en las cabezeras de los Valles de Ansó y Roncal (Pirineo Occidental)

Se estudian tres columnas estratigráficas del Cretácico superior situadas en el Soum de Léche, Collado de Petrechema y Collado de Petraficha. Abarcan desde el Cenomanense al Maestrichtiense y en ellas se describe su litología y contenido en fósiles a partir del estudio de láminas delgadas. Discordante sobre el Paleozóico se sitúa un tramo de areniscas azóicas que, por su composición, se asemejan a la Fm. Arenas de Utrillas (Albense-Cenomanense inf.). El Cenomanense está representado por calizas y calizas arenosas y arcillosas; presenta un reducido espesor (1 a 3 m) y contiene principalmente Prealveolina y Daxia: El Turonense-Coniaciense, con menos de 5 m, está constituido por biomicritas y se ha caracterizado por la presencia de "Rotalina", Tritaxia y Pithonella. El Santoniense constituye la formación más importante, -conocida como «caliza de los cañones»- con un espesor que llega a superar los 300 m. Se trata de calcarenitas con intracIastos y pellets, con abundante contenido en microfósiles, entre los que destacan Dictyopsella, Dicyclina, Cuneolina, Martiguesia y en la parte superior Lacazina. El Campaniense, con unos 55 m, comienza por calizas con nódulos de sílex o areniscas finas muy calcáreas con Monolepidorbis, a las que siguen calcilutitas arcillosas con Globotruncana y Pithonella. El Maestrichtiense comienza por calizas arcillosas con esquistosidad que contienen Globotruncana, Navarella y Rugoglobigerina, seguidas por una serie turbidítica margoso-areniscosa. Se pone de manifiesto la posible existencia de un hiato entre el Turonense y Coniacense. Los niveles del Albense-Cenomanense inf. presentan una disminución del tamaño de grano hacia el sur. La transgresión cenomanense instaura un régimen de ambiente litoral, que en el Turonense y/o Coniacense se mantiene, evolucionando a un medio de plataforma, posiblemente semiabierta, en el sector meridional. El Santoniense se ha depositado en un medio de plataforma interna carbonática con episodios de carácter arrecifal. Durante el Campaniense y parte del Maestrichtiense el medio es de plataforma externa dando paso a un medio turbidítico. Los nódulos de sílex que presenta el Campaniense en el sector septentrional pasan a silicificaciones dispersas en el sector meridional, aumentando en el mismo sentido la esquistosidad. La recristalización es más manifiesta en los tramos altos del Santoniense del sector meridional. Se muestra también la distribución estratigráfica de los principales micro fósiles determinados en la zona

Micro-Raman and Raman Imaging studies of glassy material produced by continuous wave (CW) CO2 laser irradiation of lime/pozzolan mortar

ICCC 2015, Beijing, China, 13~16 October 2015; http://iccc2015.csp.escience.cn/dct/page/1This work describes the distribution of the portlandite over the surface of the lime/pozzolan mortar and the mineral composition of the glassy material formed when the mortar was irradiated with continuous-wave-CO2 (CW-CO2) laser. Both Micro-Raman and Raman mapping have been used for structural studies. Lime/pozzolan/sand 1/1/2 mortars, 5 years at room temperature, were irradiated with CW-CO2 laser (Synrad Firestar t80, Mukilteo, WA) operating at a wavelength of 10.591 ¿m, 10P(20) CO2 laser line. Laser output: 8W, 18W and 38W (Synrad PW-250 (Mukilteo, WA)). The laser beam was focused by means of a NaCl lens of 10 cm focal length and the irradiation time was 5 seconds. Raman spectra were collected with a Raman Spectrometer (Renishaw Invia) equipped with a CCD camera, using 532 nm (Nd:YAG) excitation line. The laser on the sample was 5 mW and the integration time was 10 seconds. For mapping measurements, an area of 80 ¿m x 80 ¿m was chosen in the internal part of the glass. The step size was 5 ¿m with an individual grid size of 25 ¿m2. Glazing, vaporization and spalling process can produce over an irradiated surface with a high power laser beam. When the power density of the irradiating laser beam is high enough to raise the temperature beyond the glass transition, a glassy surface layer is formed. However, if surface temperatures are below that melting point, the vaporization of water can be produce over the material surface. Due to the small diffusivity of water vapour, its transport is hindered and an overpressure is attained. Hydraulic building materials have about 4-10% bounded water, after irradiation with the CW-CO2 laser, water vapour spread out in a vaporization front reacting with the CaO present in the sample and producing Ca(OH)2, besides a glassy surface.Peer Reviewe

Estatus de fósforo en aguas superficiales de Puerto Rico: 1989-1997.

Elevated phosphorus (P) concentrations in Puerto Rico's surface waters are suspected to be the primary cause of observed eutrophication.This paper summarizes total P concentrations (TP), historical trends, and relationships between biological and chemical parameters at twenty-two surface water monitoring stations of eleven rivers from 1989 through 1997. Four rivers had median TP concentrations in excess of 0.1 mg P/L (which is considered a threshold limit for eutrophication). The remaining seven rivers, excluding Rio Guajataca, had at least 25% of the sampling episodes exceeding 0.1 mg P/L. When all data (n = 539) were considered, TP in the central 50% of the samples (25 to 75 interquartile range) ranged from 0.04 to 0.29, with mean and median values of 0.30 and 0.09 mg P/L, respectively. Pearson correlation coefficients between TP and fecal coliform bacteria, fecal streptococcal bacteria, and total Kjeidhal nitrogen were 0.38, 0.36, and 0.84, respectively, for all the rivers combined. For rivers with the highest TP concentrations differing relationships between TP and biological and chemical parameters were obtained, thus suggesting that diverse sources were contributing to P loads in rivers. Excluding two stations in Rio Grande de Añasco and Rio Grande de Arecibo, the trend was for TP concentrations to decrease or not change from 1989 to 1997. Approximately half of the variation in P loads in all rivers combined was due to instantaneous hydrologic flow discharge, a finding which corroborates our hypothesis that a number of factors (agricultural non-point sources, background non-point sources, point sources) are contributing to the observed TP concentrations.Los niveles elevados de fósforo (P) están implicados en la eutroficación que se observa en algunos cuerpos de agua superficiales de Puerto Rico. Este trabajo resume las concentraciones de fósforo, tendencias y relaciones entre parámetros biológicos y químicos encontradas en 22 estaciones de monitoreo localizadas en 11 ríos, entre 1989 y 1997. Cuatro ríos tenían concentraciones medianas de fósforo por encima de 0.1 mg P/L (considerado un nivel umbral para la eutroficación de aguas). Las concentraciones de fósforo en los restantes siete ríos, excluyendo el Río Guajataca, excedieron valores de 0.1 mg P/L en 25% de los episodios. Al considerar todos los datos (n = 539), el 50% de las muestras (25 a 75 percentila) tenían un recorrido de 0.04 a 0.29, con medias y medianas de 0.30 y 0.09 mg P/L, respectivamente. Los coeficientes de correlación Pearson, entre fósforo total (PT) y bacterias coliformes fecales, bacterias conformes estreptococales y nitrógeno total Kjeldal fueron 0.38, 0.36 y 0.84, respectivamente, para todos los ríos combinados. Para los ríos con mayores concentraciones de fósforo, se obtuvieron diferentes relaciones entre PT y los parámetros biológicos y químicos seleccionados. Excluyendo dos estaciones en el Río Grande de Añasco y el Río Grande de Arecibo, se observó una disminución o ningún cambio en las concentraciones de fósforo entre 1989 y 1997. Aproximadamente la mitad de la variación en descargas de fósforo en todos los ríos se debió a descarga hidrológica. Estos datos corroboran nuestra hipótesis de que una combinación de factores (fuentes dispersas agrícolas, fuentes dispersas no-agrícolas y fuentes precisas) están aportando fósforo a las aguas superficiales evaluadas

Spectropolarimetric multi line analysis of stellar magnetic fields

In this paper we study the feasibility of inferring the magnetic field from polarized multi-line spectra using two methods: The pseudo line approach and The PCA-ZDI approach. We use multi-line techniques, meaning that all the lines of a stellar spectrum contribute to obtain a polarization signature. The use of multiple lines dramatically increases the signal to noise ratio of these polarizations signatures. Using one technique, the pseudo-line approach, we construct the pseudo-line as the mean profile of all the individual lines. The other technique, the PCA-ZDI approach proposed recently by Semel et al. (2006) for the detection of polarized signals, combines Principle Components Analysis (PCA) and the Zeeman Do ppler Imaging technique (ZDI). This new method has a main advantage: the polarized signature is extracted using cross correlations between the stellar spectra nd functions containing the polarization properties of each line. These functions are the principal components of a database of synthetic spectra. The synthesis of the spectra of the database are obtained using the radiative transfer equations in LTE. The profiles built with the PCA-ZDI technique are denominated Multi-Zeeman-Signatures. The construction of the pseudo line as well as the Multi-Zeeman-Signatures is a powerful tool in the study of stellar and solar magnetic fields. The information of the physical parameters that governs the line formation is contained in the final polarized profiles. In particular, using inversion codes, we have shown that the magnetic field vector can be properly inferred with both approaches despite the magnetic field regime.Comment: Accepted for publication in Astronomy and Astrophysic

Computer-Aided Diagnosis in Neuroimaging

This chapter is intended to provide an overview to the most used methods for computer-aided diagnosis in neuroimaging and its application to neurodegenerative diseases. The fundamental preprocessing steps, and how they are applied to different image modalities, will be thoroughly presented. We introduce a number of widely used neuroimaging analysis algorithms, together with a wide overview on the recent advances in brain imaging processing. Finally, we provide a general conclusion on the state of the art in brain imaging processing and possible future developments

Sliding wear resistance of biomorphic SiC ceramics

Biomorphic SiC ceramics were fabricated from four different wood precursors and their Knoop hardness and sliding wear resistance when sliding against a Si3N4 ball in air were studied. Tribological experiments were performed using a pin on disk apparatus, under normal loads of 2 and 5 N, at a sliding speed of 100 mm/s. The effects of specimen porosity and microstructure on measured wear were evaluated. A commercial sintered silicon carbide ceramic was also tested for comparison. Small differences in friction coefficient comparable to monolithic SiC ceramics were obtained. Several concurrent wear mechanisms are taking place: microfracture, plastic deformation in the Si phase and oxidation of the Si and/or SiC phase. The presence of an oxide tribolayer was assessed using fluorescence microscopy. Wear rates were found to scale with SiC content and depend on residual porosity in the composite.Peer reviewe

Reporte de formación complementaria en área de concentración en sistemas embebidos y telecomunicaciones

En este documento se presentan los tres proyectos trabajados en el área de concentración de sistemas embebidos y telecomunicaciones. El primero fue la creación del layout de un sistema electrónico implementado en tecnología de circuito impreso. El segundo fue la aplicación de la ingeniería de software en ambientes embebidos de un Serial Peripheral Interface (SPI) y, el tercero, fue el desarrollo de una fuente de switcheo tipo Buck para un tablero de instrumentación automotriz

Manganese Dioxide Supported on Porous Biomorphic Carbons as Hybrid Materials for Energy Storage Devices

A facile and low-cost method has been employed to fabricate MnO2/C hybrid materials for use as binder-free electrodes for supercapacitor applications. Biocarbon monoliths were obtained through pyrolysis of beech wood, replicating the microstructure of the cellulosic precursor, and serve as 3D porous and conductive scaffolds for the direct growth of MnO2 nanosheets by a solution method. Evaluation of the experimental results indicates that a homogeneous and uniform composite material made of a carbon matrix exhibiting ordered hierarchical porosity and MnO2 nanosheets with a layered nanocrystalline structure is obtained. The tuning of the MnO2 content and crystallite size via the concentration of KMnO4 used as impregnation solution allows to obtain composites that exhibit enhanced electrochemical behavior, achieving a capacitance of 592 F g−1 in electrodes containing 3 wt % MnO2 with an excellent cyclic stability. The electrode materials were characterized before and after electrochemical testing.Peer reviewe