6 resultados para ddc: 006.4 - 94
em Portal de Revistas Científicas Complutenses - Espanha
Resumo:
The need for continuous recording rain gauges makes it difficult to determine the rainfall erosivity factor (R-factor) of the (R)USLE model in areas without good temporal data coverage. In mainland Spain, the Nature Conservation Institute (ICONA) determined the R-factor at few selected pluviographs, so simple estimates of the R-factor are definitely of great interest. The objectives of this study were: (1) to identify a readily available estimate of the R-factor for mainland Spain; (2) to discuss the applicability of a single (global) estimate based on analysis of regional results; (3) to evaluate the effect of record length on estimate precision and accuracy; and (4) to validate an available regression model developed by ICONA. Four estimators based on monthly precipitation were computed at 74 rainfall stations throughout mainland Spain. The regression analysis conducted at a global level clearly showed that modified Fournier index (MFI) ranked first among all assessed indexes. Applicability of this preliminary global model across mainland Spain was evaluated by analyzing regression results obtained at a regional level. It was found that three contiguous regions of eastern Spain (Catalonia, Valencian Community and Murcia) could have a different rainfall erosivity pattern, so a new regression analysis was conducted by dividing mainland Spain into two areas: Eastern Spain and plateau-lowland area. A comparative analysis concluded that the bi-areal regression model based on MFI for a 10-year record length provided a simple, precise and accurate estimate of the R-factor in mainland Spain. Finally, validation of the regression model proposed by ICONA showed that R-ICONA index overpredicted the R-factor by approximately 19%.
Systematic review of Late Jurassic sauropods from the Museu Geológico collections (Lisboa, Portugal)
Resumo:
The Museu Geológico collections house some of the first sauropod references of the Lusitanian Basin Upper Jurassic record, including the Lourinhasaurus alenquerensis and Lusotitan atalaiensis lectotypes, previously considered as new species of the Apatosaurus and Brachiosaurus genera, respectively. Several fragmentary specimens have been classical referred to those taxa, but the most part of these systematic attributions are not supported herein, excluding a caudal vertebra from Maceira (MG 8804) considered as cf. Lusotitan atalaiensis. From the material housed in the Museu Geológico were identified basal eusauropods (indeterminate eusauropods and turiasaurs) and neosauropods (indeterminate neosauropods, diplodods and camarasaurids and basal titanosauriforms). Middle caudal vertebrae with lateral fossae, ventral hollow border by pronounced ventrolateral crests and quadrangular cross-section suggest for the presence of diplodocine diplodocids in north area of the Lusitanian Basin Central Sector during the Late Jurassic. A humerus collected from Praia dos Frades (MG 4976) is attributed to cf. Duriatitan humerocristatus suggesting the presence of shared sauropod forms between the Portugal and United Kingdom during the Late Jurassic. Duriatitan is an indeterminate member of Eusauropoda and the discovery of new material in both territories is necessary to confirm this systematic approach. The studied material is in according with the previous recorded paleobiodiversity for the sauropod clade during the Portuguese Late Jurassic, which includes basal eusauropods (including turiasaurs), diplodocids and macronarians (including camarasaurids and basal titanosauriforms).
Resumo:
Calcitic belemnite rostra are usually employed to perform paleoenvironmental studies based on geochemical data. However, several questions, such as their original porosity and microstructure, remain open, despite they are essential to make accurate interpretations based on geochemical analyses.This paper revisits and enlightens some of these questions. Petrographic data demonstrate that calcite crystals of the rostrum solidum of belemnites grow from spherulites that successively develop along the apical line, resulting in a “regular spherulithic prismatic” microstructure. Radially arranged calcite crystals emerge and diverge from the spherulites: towards the apex, crystals grow until a new spherulite is formed; towards the external walls of the rostrum, the crystals become progressively bigger and prismatic. Adjacent crystals slightly vary in their c-axis orientation, resulting in undulose extinction. Concentric growth layering develops at different scales and is superimposed and traversed by a radial pattern, which results in the micro-fibrous texture that is observed in the calcite crystals in the rostra.Petrographic data demonstrate that single calcite crystals in the rostra have a composite nature, which strongly suggests that the belemnite rostra were originally porous. Single crystals consistently comprise two distinct zones or sectors in optical continuity: 1) the inner zone is fluorescent, has relatively low optical relief under transmitted light (TL) microscopy, a dark-grey color under backscatter electron microscopy (BSEM), a commonly triangular shape, a “patchy” appearance and relatively high Mg and Na contents; 2) the outer sector is non-fluorescent, has relatively high optical relief under TL, a light-grey color under BSEM and low Mg and Na contents. The inner and fluorescent sectors are interpreted to have formed first as a product of biologically controlled mineralization during belemnite skeletal growth and the non-fluorescent outer sectors as overgrowths of the former, filling the intra- and inter-crystalline porosity. This question has important implications for making paleoenvironmental and/or paleoclimatic interpretations based on geochemical analyses of belemnite rostra.Finally, the petrographic features of composite calcite crystals in the rostra also suggest the non-classical crystallization of belemnite rostra, as previously suggested by other authors.
Resumo:
El presente trabajo incluye el estudio de un amplio conjunto cerámico perteneciente al yacimiento arqueológico de la Edad del Cobre y Edad del Bronce de Castillejo del Bonete. La muestra fue recuperada de distintas áreas del asentamiento durante la campaña de excavación de 2012. La investigación ha tenido como fin conocer mejor la relación forma-función de las vasijas, su proceso de fabricación, así como el modelo productivo y las posibles manifestaciones simbólicas presentes en el repertorio analizado. La metodología utilizada para cumplir con los objetivos se ha basado en la recopilación de datos, considerando una serie de variables morfológicas y tecnológicas, y su procesamiento con el empleo de técnicas estadísticas sencillas.
Resumo:
En el presente artículo analizamos los desplazamientos de cultos indígenas hispanos desde distintas áreas de la Península Ibérica hacia los principales lugares de inmigración en Hispania: las áreas mineras y las ciudades. Proponemos que estos grupos de emigrantes rendían culto en su nueva residencia a las deidades que veneraban en sus regiones de procedencia como un medio de preservar su cohesión social y su identidad cultural. La dureza de la vida laboral en las áreas mineras reforzaba la necesidad de fortalecer los lazos culturales.
Resumo:
La música puede afectar al individuo en todos sus niveles –físico, mental y espiritual–. El presente artículo se centra en el papel que ésta desempeña en el desarrollo de la vida espiritual y trascendental. Para ello, realizaremos un repaso histórico de su evolución estética y social, abordaremos dicho fenómeno a nivel fisiológico y presentaremos sus aplicaciones clínicas y sociales. Seguidamente y a modo de ejemplo de las concepciones de pensamiento occidental y oriental, trataremos la forma en que el cristianismo y el budismo conciben la música dentro de su doctrina. Finalizaremos con algunas reflexiones sobre el tema.