994 resultados para scientific journals
Resumo:
The study of the Upper Jurassic-Lower Cretaceous deposits (Higueruelas, Villar del Arzobispo and Aldea de Cortés Formations) of the South Iberian Basin (NW Valencia, Spain) reveals new stratigraphic and sedimentological data, which have significant implications on the stratigraphic framework, depositional environments and age of these units. The Higueruelas Fm was deposited in a mid-inner carbonate platform where oncolitic bars migrated by the action of storms and where oncoid production progressively decreased towards the uppermost part of the unit. The overlying Villar del Arzobispo Fm has been traditionally interpreted as an inner platform-lagoon evolving into a tidal-flat. Here it is interpreted as an inner-carbonate platform affected by storms, where oolitic shoals protected a lagoon, which had siliciclastic inputs from the continent. The Aldea de Cortés Fm has been previously interpreted as a lagoon surrounded by tidal-flats and fluvial-deltaic plains. Here it is reinterpreted as a coastal wetland where siliciclastic muddy deposits interacted with shallow fresh to marine water bodies, aeolian dunes and continental siliciclastic inputs. The contact between the Higueruelas and Villar del Arzobispo Fms, classically defined as gradual, is also interpreted here as rapid. More importantly, the contact between the Villar del Arzobispo and Aldea de Cortés Fms, previously considered as unconformable, is here interpreted as gradual. The presence of Alveosepta in the Villar del Arzobispo Fm suggests that at least part of this unit is Kimmeridgian, unlike the previously assigned Late Tithonian-Middle Berriasian age. Consequently, the underlying Higueruelas Fm, previously considered Tithonian, should not be younger than Kimmeridgian. Accordingly, sedimentation of the Aldea de Cortés Fm, previously considered Valangian-Hauterivian, probably started during the Tithonian and it may be considered part of the regressive trend of the Late Jurassic-Early Cretaceous cycle. This is consistent with the dinosaur faunas, typically Jurassic, described in the Villar del Arzobispo and Aldea de Cortés Fms.
Resumo:
The Early Miocene Napak XV locality (ca 20.5 Ma), Uganda, has yielded an interesting assemblage of fossils, including the very well represented amphicyonid Hecubides euryodon. The remarkable find of a nearly complete mandible, unfortunately with poorly preserved dentition, together with new dental remains allow us to obtain a better idea about the morphology and variability of this species. Additionally, we describe a newly discovered mandible of Hecubides euryodon from the Grillental-VI locality (Sperrgebiet, Namibia), which is the most complete and diagnostic Amphicyonidae material found in this area. Comparisons with Cynelos lemanensis from Saint Gérand le Pouy (France), the type locality, and with an updated sample of the species of amphicyonids described in Africa leads us to validate the genus Hecubides. Hecubides would be phylogenetically related to the medium and large size species of Amphicyonidae from Africa, most of them now grouped into the genera Afrocyon and Myacyon, both endemic to this continent.
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:
Several landforms found in the fold-and-thrust belt area of Central Precordillera, Pre-Andes of Argentina, which were often associated with tectonic efforts, are in fact related to non-tectonic processes or gravitational superficial structures. These second-order structures, interpreted as gravitational collapse structures, have developed in the western flank of sierras de La Dehesa and Talacasto. These include rock-slides, rock falls, wrinkle folds, slip sheets and flaps, among others; which together constitute a monoclinal fold dipping between 30º and 60º to the west. Gravity collapse structures are parallel to the regional strike of the Sierra de la Dehesa and are placed in Ordovician limestones and dolomites. Their sloping towards the west, the presence of bed planes, fractures and joints; and the lithology (limestone interbedded with incompetent argillaceous banks) would have favored their occurrence. Movement of the detached structures has been controlled by lithology characteristics, as well as by bedding and joints. Detachment and initial transport of gravity collapse structures and rockslides in the western flank of the Sierra de la Dehesa were tightly controlled by three structural elements: 1) sliding surfaces developed on parallel bedded strata when dipping >30° in the slope direction; 2) Joint’s sets constitute lateral and transverse traction cracks which release extensional stresses and 3) Discontinuities fragmenting sliding surfaces. Some other factors that could be characterized as local (lithology, structure and topography) and as regional (high seismic activity and possibly wetter conditions during the postglacial period) were determining in favoring the steady loss of the western mountain side in the easternmost foothills of Central Precordillera.
Resumo:
Mineral and chemical composition of alluvial Upper-Pleistocene deposits from the Alto Guadalquivir Basin (SE Spain) were studied as a tool to identify sedimentary and geomorphological processes controlling its formation. Sediments located upstream, in the north-eastern sector of the basin, are rich in dolomite, illite, MgO and KB2BO. Downstream, sediments at the sequence base are enriched in calcite, smectite and CaO, whereas the upper sediments have similar features to those from upstream. Elevated rare-earth elements (REE) values can be related to low carbonate content in the sediments and the increase of silicate material produced and concentrated during soil formation processes in the neighbouring source areas. Two mineralogical and geochemical signatures related to different sediment source areas were identified. Basal levels were deposited during a predominantly erosive initial stage, and are mainly composed of calcite and smectite materials enriched in REE coming from Neogene marls and limestones. Then the deposition of the upper levels of the alluvial sequences, made of dolomite and illitic materials depleted in REE coming from the surrounding Sierra de Cazorla area took place during a less erosive later stage of the fluvial system. Such modification was responsible of the change in the mineralogical and geochemical composition of the alluvial sediments.
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:
Nanotechnology is a multidisciplinary science that is having a boom today, providing new products with attractive physicochemical properties for many applications. In agri/feed/food sector, nanotechnology offers great opportunities for obtaining products and innovative applications for agriculture and livestock, water treatment and the production, processing, storage and packaging of food. To this end, a wide variety of nanomaterials, ranging from metals and inorganic metal oxides to organic nanomaterials carrying bioactive ingredients are applied. This review shows an overview of current and future applications of nanotechnology in the food industry. Food additives and materials in contact with food are now the main applications, while it is expected that in the future are in the field of nano-encapsulated and nanocomposites in applications as novel foods, additives, biocides, pesticides and materials food contact.
Resumo:
Currently, there is increasing use of nanomaterials in the food industry thanks to the many advantages offered and make the products that contain them more competitive in the market. Their physicochemical properties often differ from those of bulk materials, which require specialized risk assessment. This should cover the risks to the health of workers and consumers as well as possible environmental risks. The risk assessment methods must go updating due to more widespread use of nanomaterials, especially now that are making their way down to consumer products. Today there is no specific legislation for nanomaterials, but there are several european dispositions and regulations that include them. This review gives an overview of the risk assessment and the existing current legislation regarding the use of nanotechnology in the food industry.
Resumo:
The aim of this study was to determine the haematological value and biochemical blood in baby alpacas with enteric disorder. A total of 30 blood and serum samples were collected from alpacas of 1 month old with diarrhoea and 5 blood samples of clinically healthy baby alpacas (controls). The animals were from communities in the central Andes from Peru. About haematology were determined haematocrit, haemoglobin concentration, red blood count and white blood count that were not significantly different between control animals and animals with diarrhoea. Moreover, biochemical blood parameters as total protein, albumin and calcium decrease significantly (p<0.05). We conclude that our results could be considered as factors in the mortality of baby alpaca by infectious diarrhoea.
Resumo:
Este artículo tiene como objetivo fundamental mostrar cómo el Instituto de Investigaciones y Experiencias Cinematográficas (IIEC) fue, desde finales de los años cuarenta hasta mediados de los años sesenta, el creador de una escuela de maestros de la luz y cómo la enseñanza de estos nuevos métodos de iluminación traspasó las fronteras de las aulas y marcó el inicio del Nuevo Cine Español. Para ello se han revisado las principales fuentes bibliográficas de los que consideramos fueron los primeros maestros de fotografía que dio el IIEC: Juan Julio Baena, Luis Enrique Torán y Luis Cuadrado, y se ha realizado un análisis fílmico de la primera obra audiovisual de cada uno en la que se instaura un ambiente de renovación, un cambio estético y el uso de unas técnicas fotográficas más realistas. Así mismo, hemos observado cómo la nueva docencia de la fotografía fue trasladada a otras personas que también llegaron a ser maestros y no estudiaron en el IIEC. Por tanto, se trata de una escuela generadora de maestros tanto dentro como fuera de sus aulas.
Resumo:
En este artículo se recoge la historia de la enseñanza oficial de cine en España: los dos centros en los que se llevó a cabo, sus sedes, sus directores y las prácticas de fin de carrera. Todo ello visto desde la división en tres etapas del tiempo de existencia de la enseñanza anterior a su incorporación a la universidad: la etapa fundacional, la edad de oro y la crisis que lleva al cierre. A lo largo de estas tres etapas hubo un cambio de actitud en el alumnado, desde el entusiasmo y la ilusión inicial al desencanto y rechazo absoluto hacia la Escuela en los últimos años.
Resumo:
Este artículo pretende demostrar en qué medida Paseo por una guerra antigua (1948-1949), la práctica de segundo curso del Instituto de Investigaciones y Experiencias Cinematográficas (IIEC) en la que Juan Antonio Bardem rueda a un joven mutilado caminando por las ruinas de la Ciudad Universitaria de Madrid, constituye un intento pionero de desmontar los relatos oficiales de la Guerra Civil Española y rescatar la memoria de los vencidos. Filmar las ruinas del campus madrileño en aquellos años era un acto subversivo, puesto que el Régimen había emprendido su reconstrucción para borrar las huellas del Madrid republicano y de la Guerra Civil, resignificando por completo el recinto universitario. Por tanto, en Paseo por una guerra antigua, Bardem intenta reapropiarse de un espacio que en la época iba imponiéndose como uno de los “lugares de memoria” del franquismo. Esta película se vale de la función documental del cine para inmortalizar unas ruinas que simbolizan la República y la guerra, para preservarlas de la muerte simbólica que representa su reconstrucción. Mostrar esas ruinas en 1948-1949 equivale a “materializar” el pasado, a traerlo al presente de la posguerra, en un proceso que recuerda a los planteamientos sobre la Historia de Walter Benjamin, para proponer una visión alternativa de la contienda. Se trata de una visión teñida de una memoria íntima, ya que la película es un paseo no solo por las ruinas sino también por los recuerdos de este joven mutilado. En suma, Bardem propone una contramemoria de la Guerra Civil.
Resumo:
El carácter innovador y feminista del mediometraje Margarita y el lobo (1969) supuso la censura total de la película y el ostracismo hacia su directora, la entonces estudiante de la EOC, Cecilia Bartolomé. En este artículo repasamos sus anteriores cortometrajes para desgranar los primeros matices de protesta así como la utilización de la expresión musical como vehículo del discurso feminista en Margarita y el lobo. A través de los planteamientos de la musicóloga Susan McClary que abordan sexualidad, género y feminismo concluimos con una visión del análisis de género en las obras musicales, al vincular sus estudios al film de Bartolomé. Del mismo modo, analizamos la función que cumple la música en el mediometraje. Para ello, examinamos el repertorio de canciones presente en Margarita y el lobo para terminar reconociendo la función discursiva y referencial como piezas claves en la película de la directora.
Resumo:
El presente texto analiza la función del Instituto de Investigaciones y Experiencias Cinematográficas (IIEC) como punto de encuentro de la cultura cinematográfica nacional entre 1947 y 1955 —los años de Victoriano López— y dirige el foco analítico a los discursos, debates e intereses que marcaron la labor del instituto en estos primeros años. Para ello, este artículo fija su atención en uno de los pocos documentos originales conservados de esa época, un boletín publicado por los alumnos en 1951, material que será aquí completado con entrevistas y los escasos documentos referentes al instituto conservados en el Archivo General de la Administración. La piedra de toque del análisis la constituyen por un lado las actividades del cineclub, organizado por los alumnos de la clase de Historia del Cine en 1951, y, en el plano discursivo, los debates en torno a la Filmología, doctrina con la que desde 1947 se intenta dotar a las actividades del Instituto de una base teórica con desiguales resultados. Se consigue así un acercamiento a las prácticas y discursos esenciales para comprender la importancia del instituto como punto central dentro de una naciente cultura cinematográfica nacional.
Resumo:
Aunque Víctor Erice es uno de los directores españoles más estudiados del cine español, sus trabajos en el Instituto de Investigaciones y Experiencias Cinematográficas, que más tarde pasará a llamarse Escuela Oficial de Cinematografía, no se han analizado en profundidad. Salvo su práctica de tercer curso, Los días perdidos, el resto de los cortometrajes y los guiones escritos se han considerado obras menores, piezas sin importancia relevante o directamente títulos extraviados. Sin embargo, estos trabajos se encuentran en buen estado en el archivo de la Escuela Oficial de Cine custodiado por la Filmoteca Española. De Víctor Erice se conservan cuatro cortometrajes y cinco guiones cinematográficos para piezas breves. En este artículo, resumen de una investigación realizada sobre dicho material inédito, se quiere mostrar cómo estas obras presentan un valor en sí mismas y deben ser analizadas como parte importante de la filmografía de este autor. En todos estos trabajos, sin dejar de ser ejercicios de escuela, se muestra la mirada de un cineasta pleno. Así, existen elementos que serán clave en el posterior universo temático y estético de Víctor Erice. Además, el creador aborda como problemática central de sus prácticas el tema de la comunicación humana, o más propiamente el de la incomunicación. En los guiones y los cortometrajes catalogados de la etapa en la EOC se observa cómo Erice, influenciado en parte por Michelangelo Antonioni, investiga estéticamente el modo de narrar y mostrar los procesos que conducen a la incomunicación y al aislamiento de sus protagonistas.