1,721,057 research outputs found
A large-clawed theropod (Dinosauria: Tetanurae) from the Lower Cretaceous of Australia and the Gondwanan origin of megaraptorid theropods
No full textMegaraptoridae comprises a clade of enigmatic Gondwanan theropods with characteristic hypertrophied claws
on the first and second manual digits. The majority of megaraptorids are known from South America, although a
single genus (Australovenator) plus additional indeterminate material is also known from Australia. This clade
has a controversial placement among theropods, and recently has been interpreted alternatively as a
carcharodontosaurian or a tyrannosauroid lineage. We describe new fragmentary but associated postcranial remains
from the opal fields of Lightning Ridge (middle-Albian, Griman Creek Formation) in north-central New
South Wales. The new unnamed taxon exhibits a number of unusual features that suggest the presence of a hitherto
unrecognised Australian megaraptorid. From an Australian perspective, the Lightning Ridge taxon predates
Australovenator by ca. 10 Ma and is minimally coeval with megaraptoran material reported from the Eumeralla
Formation of Victoria (but potentially 6.1–9.5 Ma younger). It is also notable as the largest predatory dinosaur
yet identified from Australia and is only the second theropod known from more than a single element. A Bayesian
phylogenetic approach integrating morphological, stratigraphic and palaeogeographic information tested both
the carcharodontosaurian and tyrannosauroid placements for Megaraptora. Regardless of the preferred placement
among Tetanurae, rigorous palaeobiogeographic analyses support an Asian origin of Megaraptora in the latest
Jurassic (about 150–135 Ma), an Early Cretaceous (about 130–121 Ma) divergence of the Gondwanan lineage
leading to Megaraptoridae, and an Australian root for megaraptorid radiation. These results indicate that
Australia's Cretaceous dinosaur fauna did not comprise simply of immigrant taxa but was a source for complex
two-way interchange between Australia–Antarctica–South America leading to the evolution of at least one
group of apex predatory dinosaurs in Gondwan
The scaly skin of the abelisaurid Carnotaurus sastrei (Theropoda: Ceratosauria) from the Upper Cretaceous of Patagonia
No full textThe integument of the theropod dinosaur Carnotaurus sastrei from the Upper Cretaceous of Argentina is here described in detail for the first time. The scaly skin of this abelisaurid is the most completely preserved of any theropod and the only example of this form of integument known outside of Tetanurae (excluding footprints). The skin is preserved in the shoulder, thoracic, tail and, possibly, neck regions and consists of medium to large (20–65 mm in diameter) conical feature scales surrounded by a network of low and small (1000 kg), we speculate that the skin may have played a vital role in thermoregulation; a role consistent with integument function in extant mammals and reptiles.Fil: Hendrickx, Christophe Marie Fabian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - Tucumán. Unidad Ejecutora Lillo; ArgentinaFil: Bell, Phil R.. University Of New England Australia; Australi
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Crocodile-like sensory scales in a Late Jurassic theropod dinosaur
No full textEarly in amniote evolution, epidermal scales evolved in stem reptiles as an efficient barrier against water loss and ultraviolet radiation, making them a key development in the transition to a fully terrestrial existence [1]. Accordingly, epidermal scales are not simple inert structures but highly-evolved organs suited to perform a broad suite of functions. Here, we provide new data on the epidermal complexity of a non-avian theropod, Juravenator starki, from the Torleite Formation (upper Kimmeridgian), Bavaria, Germany [2]. Although epidermal scales have been noted previously on the tail of Juravenator, we report a unique scale type with distinctive circular nodes that we identify as integumentary sense organs, analogous to those in modern crocodylians. The surprising presence of such structures suggests the tail had a sensory function, which is nevertheless congruent with the inferred ecology of Juravenator and the evolution of integumentary sense organs among archosaurs. Bell and Hendrickx describe evidence for a crocodile-like sensory system of integumentary sense organs (ISOs) from fossilised soft tissues on the diminutive theropod dinosaur Juravenator from the Jurassic of Bavaria.Fil: Bell, Phil R.. University Of New England Australia; AustraliaFil: Hendrickx, Christophe Marie Fabian. Fundación Miguel Lillo; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin
Large-enrollment STEM Learning Environments: Cultural and experimental perspectives
No full textThesis (Ph.D.)--University of Washington, 2015Post-secondary STEM education forces students through an experiential bottleneck in the form of large-enrollment lecture courses. At colleges and universities around the world, talented students who have already passed through several academic filtering processes are challenged with coursework in environments that are impersonal, intimidatingly large, and typically taught using traditional passive lecture techniques. This is no way to educate the next generation of scientists, researchers, doctors, and innovators. Calls for improvement are frequent and loud, but the research on improvement in this unique arena is seldom conclusive useful for practitioners. This dissertation focuses on the large-enrollment STEM classroom as an opportunity for inspection and change. This dissertation seeks a wide-spectrum view across several key issues. Comprised of peer-reviewed articles, this work will examine the large-enrollment STEM classroom from four angles. First, an analysis of interactions between different types of teaching assistants will inform the student-instructor relationship and speak to important attributes in instructor teams. Secondly, the methods for modeling large education environments through social network analysis are developed. Third, a qualitative deep dive into student experiences is used to develop a survey instrument focused on student engagement with active teaching practices in a large-enrollment classroom; these mixed methods triangulate similar conclusions about the important factors for students. Lastly, predictions at the apex of the ICAP framework for active learning practices developed by Chi and Wylie (2014) are validated through an experimental use of split large-lecture courses as a model system. This dissertation is intentionally broad. As this learning environment is yet poorly understood, the author intends to address change in future work through a wider scope on multiple avenues for positive change. While this does not address any particular issues in the depth of multiple peer reviewed papers, it is agreed by the committee that a group-authored and collaborative look at multiple issues is a useful education for potential needs of post-secondary STEM education overall
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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