Concreciones carbonatadas en margas del Eoceno: consecuencias geomorfológicas

[Resumen] Las margas del Eoceno de la cuenca de Jaca (Pirineo Central) presentan, en numerosos lugares, una topografía de detalle muy característica, en la que destacan un conjunto de núcleos más resistentes de aspecto frecuentemente esférico y de orden métrico, que permiten hablar de un paisaje de "margas con bolas". Se trata en realidad de concreciones dolomíticas interestratificadas, menos susceptibles a los procesos erosivos que las propias margas. En este trabajo hemos intentado establecer si las diferencias mineralógicas entre concreciones carbonatadas y margas encajantes permiten explicar esta meteorización diferencial; para ello se ha estudiado la mineralogía de las concreciones, las margas y las margas alteradas. Se concluye que los procesos químicos de alteración resultan insuficientes para explicar las diferentes tasas erosivas, debiendo por tanto atribuirse a causas físicas (susceptibilidad ante la helada, procesos de humectación-desecación) la mayor erosionabilidad de las margas frente a las concreciones carbonatadas y areniscas interestratificadas.[Abstract] The Eocene marls from the Jaca basin (Central Pyrenees) show a conspicuous morphologic feature consisting of disperse hard cores, often with an spherical shape and metric size, surrounded by the marly matrix. These hard cores are dolomitic concretions isolated from the marls because of less intense weathering. In this paper we study the mineralogical composition of dolomitic concretionsand marls, in order to better define the differences in weathering processes. We conclude that chemical weathering processes do not fully explain the differences of erosion rates. We propose physical processes (frost susceptibility, dry-moist alternations) as the main erosion factors in the Eocene marls and, consequently, they are responsible for the greater erodibility of the marls compared to the dolomite concretions and interlayered sandstones

Estudio de la materia en suspensión en el Golfo de Cádiz

Las principales fuentes de aporte de material particulado en suspensión en el Golfo de Cádiz son los ríos Guadiana, Tinto-Odiel y Guadalquivir. Estos ríos generan plumas de material particulado que se desplazan arrastradas por las corrientes litorales paralelamente a la costa y por advección. En la  plataforma, las suspensiones se concentran mayoritariamente en una capa de turbidez situada sobre el fondo. La sedimentación de partículas en la plataforma y la difusión hacia el mar abierto son procesos que hacen descender la concentración de materia en suspensión en el borde de la plataforma y en el talud. En la zona profunda se ha detectado un aumento de partículas hacia el sureste

Programa para el cálculo de F0 a partir de las intensidades obtenidas en un difractómetro automático de cristal único

El programa elaborado para IBM-1130, lee los contajes de intensidad de cada reflexión en una cinta perforada para luego de su posterior corrección de Lorentz -polarización- calcular la intensidad neta, F0 F2 ponderación, así como la calidad de la medida respecto a una σ determinada; dando por último el valor medio de la reflexión de referencia y el número de intensidades perforadas y observadas.Peer reviewe

Preparación de agregados orientados de arcilla mediante extensor

Se detalla un método nuevo para la preparación de agregados orientados de arcilla para sus análisis por Difracción de Rayos X. Se trata de emplear un extensor para obtener un grosor constante de material, que por su delgadez seca rápidamente, economizándose tiempo y espacio en el laboratorio, obteniéndose además mejores resultados que con el método convencional

Estructura cristalina y molecular de la 2 etoxi isonitrosoacetanilida

In this paper, the crystal and molecular structure of the 2 ethosy isonitroseacetanilide has been solved by means of the X-ray diffraction and the direct methods. This compound is a isonitroseacetanilide derivative by sustitution of the ORTO hydrogen benzene ring by an ethoxy group. Space group: Pccn. Unit cell dimensions : n : 10.964 4 b : 21.884 A, c: 9.463 A, Z : 8

Estructura cristalina y molecular de la dihidrazida malonica anhidra

En este trabajo se presenta la estructura cristalina y molecular de la hidracida malónica anhidra. La estructura cristalina ha sido resuelta por difracción de Rayos X. Las dimensiones de la celda elemental son: (...

Modificacion del programa ORTEP de C.K. Johnson

Se presenta una modificación del programa Ortep, con vistas a su empleo en ordenadores de reducida capacidad de memoria. Con dichas modificaciones se pasa de una capacidad de 128 k a una de 84 k, que es la máxima permisible en el IBM 360/30 de que dispone la Facultad de Ciencias de la Universidad de Barcelona.On présente une modification du programme Ortep, a fin de pouvoir l'employer sur des ordinateurs de capacité de mémoire réduite. Avec cettes modifications on réduit la capacité de mémoire de 123 k i 84 k, que correspond à celle du modele 360/30 de la Faculté des Sciences de 1'Université de Barcelone

Galaxy evolution in nearby groups. II. Galaxy evolution in nearby loose groups. II. Photometric and kinematic characterization of USGC U268 and USGC U376 group members in the Leo cloud

We present the photometric and kinematic characterization of two groups, USGC U268 and USGC U376 located in different regions of the Leo cloud. U268, composed of 10 catalogued members and 11 new added members, has a small fraction (~24%) of early-type galaxies (ETGs). U376 has 16 plus 8 new added members, with ~38% of ETGs. We find the presence of significant substructures in both groups suggesting that they are likely accreting galaxies. U268 is located in a more loose environment than U376. For each member galaxy, broad band integrated and surface photometry have been obtained in far-UV and near-UV with GALEX, and in u,g, r, i, z (SDSS) bands. H_alpha imaging and 2D high resolution kinematical data have been obtained using PUMA Scanning Fabry-Perot interferometer at the 2.12 m telescope in San Pedro M\'artir, (Baja California, M\'exico). We improved the galaxy classification and we detected morphological and kinematical distortions that may be connected to either on-going and/or past interaction/accretion events or environmental induced secular evolution. U268 appears more active than U376, with a large fraction of galaxies showing interaction signatures (60% vs. 13%). The presence of bars among late-type galaxies is ~10% in U268 and ~$29% in U376. The cumulative distribution of (FUV - NUV) colours of galaxies in U268 is significantly different than that in U376 with galaxies in U268 bluer than those in U376. In the (FUV-r vs. M_r) and (NUV-r vs. M_r) planes no members of U268 are found in the `red sequence', even early-type galaxies lie in the `blue sequence' or in the `green valley'. Most (80%) of the early-type members in U376 inhabits the `red sequence, a large fraction of galaxies, of different morphological types, are located in the `green valley', while the `blue sequence' is under-populated with respect to U268.Comment: 27 pages, 11 figures, 8 tables, accepted for publication in MNRAS (abridged abstract

An international prospective general population-based study of respiratory work disability

Background: Previous cross-sectional studies have shown that job change due to breathing problems at the workplace (respiratory work disability) is common among adults of working age. That research indicated that occupational exposure to gases, dust and fumes was associated with job change due to breathing problems, although causal inferences have been tempered by the cross-sectional nature of previously available data. There is a need for general population-based prospective studies to assess the incidence of respiratory work disability and to delineate better the roles of potential predictors of respiratory work disability.Methods: A prospective general population cohort study was performed in 25 centres in 11 European countries and one centre in the USA. A longitudinal analysis was undertaken of the European Community Respiratory Health Survey including all participants employed at any point since the baseline survey, 6659 subjects randomly sampled and 779 subjects comprising all subjects reporting physician-diagnosed asthma. The main outcome measure was new-onset respiratory work disability, defined as a reported job change during follow-up attributed to breathing problems. Exposure to dusts (biological or mineral), gases or fumes during follow-up was recorded using a job-exposure matrix. Cox proportional hazard regression modelling was used to analyse such exposure as a predictor of time until job change due to breathing problems.Results: The incidence rate of respiratory work disability was 1.2/1000 person-years of observation in the random sample (95% CI 1.0 to 1.5) and 5.7/1000 person-years in the asthma cohort (95% CI 4.1 to 7.8). In the random population sample, as well as in the asthma cohort, high occupational exposure to biological dust, mineral dust or gases or fumes predicted increased risk of respiratory work disability. In the random sample, sex was not associated with increased risk of work disability while, in the asthma cohort, female sex was associated with an increased disability risk (hazard ratio 2.8, 95% CI 1.3 to 5.9).Conclusions: Respiratory work disability is common overall. It is associated with workplace exposures that could be controlled through preventive measures

Confusion Assessment Method for the intensive care unit (CAM-ICU) for the diagnosis of delirium in adults in critical care settings

© 2018 The Cochrane Collaboration. This is a protocol for a Cochrane Review (Diagnostic test accuracy). The objectives are as follows: To determine the diagnostic accuracy of the Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) for the diagnosis of delirium in adult patients in critical care settings