1,721,113 research outputs found
Secondary Aluminum Alloys Processed by Semisolid Process for Automotive Application
No full textOEMs manufacturers of aluminum based safety components for automotive sector are used to require low percentage of Fe as contaminant, since it can be responsible of very high brittle microstructure due to formation of acicular Fe-compounds. Lowest Fe percentage is achieved by alloying primary aluminum, instead of secondary aluminum obtained on recycling marketplace. On the other hand, any aluminum alloys fabricated starting from primary aluminum achieves very high environmental impact, due to very high CO2equivalent emitted during the early extractive stage. In order to reduce total global warming potential of finished components, recycling alloys would be preferred, but metallurgy solutions are necessary to control Fe-contaminants. According to recent advancements, Fe-compounds in recycled aluminum could be controlled throughout semisolid processes, where the stirring phase of a semisolid slurry would produce fragmentation Fe-compounds. In this work, investigation about key process parameters has been performed to correlate microstructural features to mechanical properties in presence of Fe-compound. Among various process parameters, stirring time and solid fraction are most important key parameters to control to obtain fine globular microstructure. Tensile tests have been performed showing promising results (yield strength about 300 MPa and ultimate tensile stress about 330 MPa). Stirring stage in semisolid process allows reduction of average size of Fe-compounds, thus producing an increase in percentage elongation and toughness, namely the main requirements in automotive sector for widespread use of low-cost and low-environmental impact aluminum alloys
Macroscopic and Endoscopic Anatomy of the Anterior Skull Base and Adjacent Structures
No full textThe anterior skull base can be divided into three segments: a midline and two symmetrically placed segments located laterally. The midline segment is the roof of the nasal cavity and serves as a watershed between the sinonasal tract and the intracranial space, whereas the lateral segments separate the intracranial compartment from the orbital content. Several peculiar anatomical areas make up the midline segment (posterior frontal plate, cribriform plate, ethmoidal roof, planum sphenoidale, and tuberculum sellae), while the lateral segments are more regular, formed by flat laminae (orbital plates of the frontal bones and lesser wings of the sphenoid). Here we detail each segment of the anterior skull base, emphasizing major landmarks, providing classifications and measurements of key areas, and cautioning the endoscopist about areas to avoid or minimize the occurrence of cerebrospinal fluid leaks, as well as providing recommendations and tips. Several endoscopic and sectional macroscopic anatomical images provide the reader with an informative, illustrative, and broad perspective of anterior skull base anatomy
Management of sinonasal adenocarcinomas with anterior skull base extension
No full textINTRODUCTION: Sinonasal adenocarcinomas (SNAC) are rare and heterogeneous. Management of SNAC follows a rather standardized and internationally accepted paradigm. Several refinements have been introduced during the last decade. METHODS: A narrative review of most updated literature on SNACs has been conducted. RESULTS: SNACs are classified as intestinal-type and non-intestinal-type, which are further categorized according to grade. Preoperative work-up should include magnetic resonance imaging (or contrast-enhanced computed tomography as a secondary or complementary choice) and biopsy under general anesthesia, or under local anesthesia in case of a history of exposure to wood and/or leather dust. Positron emission tomography, neck ultrasound, and fine-needle aspiration cytology are indicated in selected cases. Surgery represents the most common upfront modality of treatment and is usually accomplished via a transnasal endoscopic approach. Adjuvant radiation therapy is indicated for high-grade, locally advanced tumors and/or in case of margins involvement. Neoadjuvant chemotherapy with cisplatin, 5-fluorouracil and leucovorin may offer high response rates and long-term control in a subgroup of patients affected by intestinal-type adenocarcinoma, and in particular in those whose tumors harbor a functional p53 protein. Most of the bio- and immune-therapeutic potentials on SNACs still remain theoretical, and no clinical data are currently available. CONCLUSIONS: Management of SNAC consists of histological diagnosis, radiological staging, radical surgery, and adjuvant radiation therapy. Neoadjuvant chemotherapy can be indicated in selected cases. The role of biotherapy and immune therapy still needs to be elucidated
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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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