4,789 research outputs found

    A middle Jurassic abelisaurid from Patagonia and the early diversification of theropod dinosaurs

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    Abelisaurids are a clade of large, bizarre predatory dinosaurs, most notable for their high, short skulls and extremely reduced forelimbs. They were common in Gondwana during the Cretaceous, but exceedingly rare in the Northern Hemisphere. The oldest definitive abelisaurids so far come from the late Early Cretaceous of South America and Africa, and the early evolutionary history of the clade is still poorly known. Here, we report a new abelisaurid from the Middle Jurassic of Patagonia, Eoabelisaurus mefi gen. et sp. nov., which predates the so far oldest known secure member of this lineage by more than 40 Myr. The almost complete skeleton reveals the earliest evolutionary stages of the distinctive features of abelisaurids, such as the modification of the forelimb, which started with a reduction of the distal elements. The find underlines the explosive radiation of theropod dinosaurs in the Middle Jurassic and indicates an unexpected diversity of ceratosaurs at that time. The apparent endemism of abelisauroids to southern Gondwana during Pangean times might be due to the presence of a large, central Gondwanan desert. This indicates that, apart from continent-scale geography, aspects such as regional geography and climate are important to reconstruct the biogeographical history of Mesozoic vertebrates.Fil: Pol, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Museo Paleontológico Egidio Feruglio; ArgentinaFil: Rauhut, Oliver W. M.. Ludwig Maximilians Universitat; Alemani

    Probable basal allosauroid from the early Middle Jurassic Canadon Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs

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    Tetanurae, the most successful clade of theropod dinosaurs, including modern birds, split into three major clades early in their evolutionary history: Megalosauroidea, Coelurosauria, and Allosauroidea. The oldest tetanurans occur in the earliest Middle Jurassic, but the early fossil record of the clade is still poor. Here we report one of the oldest known and most complete pre-Late Jurassic tetanuran, the probable allosauroid Asfaltovenator vialidadi gen. et sp. nov., which has an unusual character combination, uniting features currently considered to be apomorphic of different tetanuran lineages. A phylogenetic analysis resulted in a monophyletic Carnosauria (Allosauroidea + Megalosauroidea), and the inclusion of the new taxon significantly changes topology within carnosaurs. The analysis shows concentrated homoplasy in proximal nodes at the base of Tetanurae, and a temporal peak at the Pliensbachian-Toarcian extinction event, recently identified as a potential driver of tetanuran radiation. These results highlight the complex morphological evolution in the early radiation of tetanuran theropods, in which convergences and parallelisms were extremely common. This pattern seems to be a common feature in rapid radiation events of major clades of vertebrates and might explain the common difficulties to unravel phylogenetic relationships of important lineages at the base of major clades

    Social Outcasts in A Streetcar Named Desire and Cat on a Hot Tin Roof by Tennessee Williams

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    El objetivo principal de este Trabajo de Fin de Grado es analizar a los “outcasts”, los marginados de la sociedad, en dos de las obras más celébres del escritor Tennessee Williams: A Streetcar Named Desire y Cat on a Hot Tin Roof. Williams fue uno de los pocos autores que dio voz e hizo visibles a estos personajes, que siempre habían estado silenciados, convirtiéndolos en protagonistas de sus obras y dotándoles de profundidad psicológica, así como de cuestionar ciertas normas sociales y clichés. Proponiéndose así denunciar la sociedad de los años 40 y 50 en la que vivía, basada en el sistema patriarcal y la persecución a los homosexuales, mostrándonos el efecto devastador que pueden tener las convenciones sociales en las personas a través de sus personajes, los cuales se veían obligados a mentir y a aparentar, causándoles un gran sufrimiento, para seguir los estereotipos tradicionales de lo que un hombre y una mujer deberían ser, ya que en esa época ser diferente a los demás era realmente peligroso. Esto se conseguirá estudiando especialmente a los personajes femeninos y homosexuales, como Blanche, Maggie o Brick

    A Multi-facetted Visual Analytics Tool for Exploratory Analysis of Human Brain and Function Datasets

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    Brain research typically requires large amounts of data from different sources, and often of different nature. The use of different software tools adapted to the nature of each data source can make research work cumbersome and time consuming. It follows that data is not often used to its fullest potential thus limiting exploratory analysis. This paper presents an ancillary software tool called BRAVIZ that integrates interactive visualization with real-time statistical analyses, facilitating access to multi-facetted neuroscience data and automating many cumbersome and error-prone tasks required to explore such data. Rather than relying on abstract numerical indicators, BRAVIZ emphasizes brain images as the main object of the analysis process of individuals or groups. BRAVIZ facilitates exploration of trends or relationships to gain an integrated view of the phenomena studied, thus motivating discovery of new hypotheses. A case study is presented that incorporates brain structure and function outcomes together with different types of clinical data

    Towards Semantics for Abstractions in Ontology-Driven Conceptual Modeling

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    Ontology-driven conceptual models are precise and semantically transparent domain descriptions that enable the development of information systems. As symbolic artefacts, such models are usually considered to be self-explanatory. However, the complexity of a system significantly correlates with the complexity of the conceptual model that describes it. Abstractions of both conceptual models and ontology-driven conceptual models are thus considered to be a promising way to improve the understandability and comprehensibility of those models. Although algorithms for providing abstractions of such models already exist, they still lack precisely formulated formal semantics. This paper aims to provide an approach towards the formalization of the abstraction process. We specify in first-order modal logic one of the graph-rewriting rules for ontology-driven conceptual model abstractions, in order to verify the correctness of the corresponding abstraction step. We also assess the entire network of abstractions of ontology-driven conceptual models and discuss existing drawbacks

    A Middle Jurassic heterodontosaurid dinosaur from Patagonia and the evolution of heterodontosaurids

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    Heterodontosauridae is a morphologically divergent group of dinosaurs that has recently been interpreted as one of the most basal clades of Ornithischia. Heterodontosaurid remains were previously known from the Early Jurassic of southern Africa, but recent discoveries and studies have significantly increased the geographical and temporal range for this clade. Here, we report a new ornithischian dinosaur from the Middle Jurassic Cañadón Asfalto Formation in central Patagonia, Argentina. This new taxon, Manidens condorensis gen. et sp. nov., includes well-preserved craniomandibular and postcranial remains and represents the only diagnostic ornithischian specimen yet discovered in the Jurassic of South America so far. Derived features of its anatomy indicate that Manidens belongs to Heterodontosauridae, as the sister taxon of Heterodontosaurus and other South African heterodontosaurids. The presence of posterior dentary teeth with high crowns but lacking extensive wear facets in Manidens suggests that this form represents an intermediate stage in the development of the remarkable adaptations to herbivory described for Heterodontosaurus. The dentition of Manidens condorensis also has autapomorphies, such as asymmetrically arranged denticles in posterior teeth and a mesially projected denticle in the posteriormost teeth. At an estimated total length of 60-75 cm, Manidens furthermore confirms the small size of basal heterodontosaurids.Fil: Pol, Diego. Museo Paleontológico Egidio Feruglio; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rauhut, Oliver Walter Mischa. Ludwig Maximilians Universitat; AlemaniaFil: Becerra, Marcos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ciencias Geológicas; Argentin

    Thermal properties and crystallization of iron phosphate glasses containing up to 25 wt% additions of Si-, Al-, Na- and U-oxides

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    This work is dedicated to the memory of Professor Peter Finlay James, who deceased on 2nd July, 2005.The thermal properties (expansion, Tg and TSOFT.) of glasses, having 56–66% P2O5, 14.8–34.2% Fe2O3 and 2–25 wt% additions of SiO2, Al2O3, Na2O and UO2, were comparatively estimated from dilatometric measurements in similar conditions. The Tg reversibility was clearly verified by varying the heating rates between 1 and 5 °C min−1. From linear equations fits of the various glass properties as functions of the six components it is suggested the iron, sodium and uranium oxides decrease the thermal expansion (for 50 < T ⩽ 300 °C), Tg andTSOFT. From DTA/XRD analysis of three glasses it was confirmed the crystallization tendency decreased with increasing the UO2 level in the glasses. Leaching test data for two compositions containing Na2O suggest addition of UO2 increases the chemical durability of the related glass. The roles of UO2, Na2O and Fe-oxide species as structural components of the glass network are discussed.The authors thank Messrs C. Cotaro, E. Scerbo and J. Menghini [Centro Atómico Bariloche] for the EDS/Edax analysis and leaching tests; Messrs. M. Sanfilippo and A. Heredia for their help in sample preparation; and Dr R.D. Pérez (CEPROCOR, Córdoba) for the X-rays fluorescence analysis. The financial support of the Centro Atómico Bariloche Superconductivity Group, which allowed the purchase of the main parts of the dilatometer is acknowledged. Financial help of J. Ma. Rincón for stage at CAB supported by IAEA, Viena, is much appreciated as well as the financial support of Univ. Nac. de Cuyo and C.O.N.I.C.E.T.Peer reviewe
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