1,720,984 research outputs found
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
Mapping of binding sites for monoclonal antibodies to chick tropoelastin by recombinant DNA techniques.
No full textA fusion molecule consisting of the entire coding sequence of mature chicken tropoelastin preceded by 14 amino acids of the signal peptide and 9 amino acids of vector origin has been expressed in a recombinant bacterial system and purified. The molecule has been used as immunogen for the production of hybridomas. Monoclonal antibodies which bound specifically the immunogen were also reactive with tropoelastin purified from chick aorta and stained elastic fibers in aorta sections by immunofluorescence. The region of tropoelastin containing the antigenic determinant recognized by each antibody has been identified by a recombinant DNA expression strategy based on the use of cDNA clones spanning different portions of the coding sequence. It could be shown that several antibodies were directed against unique epitopes; among these, a group of antibodies bound specifically to the sequence (PGVGV)n. Other antibodies were found to recognize antigenic determinants present more than once in the molecule. The monoclonal antibodies thus characterized will be useful reagents in studying the function of the different domains of tropoelastin
Mapping of binding sites for monoclonal antibodies to chick tropoelastin by recombinant DNA techniques.
No full textA fusion molecule consisting of the entire coding sequence of mature chicken tropoelastin preceded by 14 amino acids of the signal peptide and 9 amino acids of vector origin has been expressed in a recombinant bacterial system and purified. The molecule has been used as immunogen for the production of hybridomas. Monoclonal antibodies which bound specifically the immunogen were also reactive with tropoelastin purified from chick aorta and stained elastic fibers in aorta sections by immunofluorescence. The region of tropoelastin containing the antigenic determinant recognized by each antibody has been identified by a recombinant DNA expression strategy based on the use of cDNA clones spanning different portions of the coding sequence. It could be shown that several antibodies were directed against unique epitopes; among these, a group of antibodies bound specifically to the sequence (PGVGV)n. Other antibodies were found to recognize antigenic determinants present more than once in the molecule. The monoclonal antibodies thus characterized will be useful reagents in studying the function of the different domains of tropoelastin
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
Fracture Toughness Characterization of Copper-Resin Interface in Power Electronics Application
No full textThe use of molding compound as encapsulating material is nowadays increasing in semiconductor industry. Such component guarantees excellent thermal and reliability performances than the current silicone-based gel, enabling higher working temperature for semiconductor device and mitigating the solder joint reliability bottleneck. The adhesion of package interfaces between copper components and molding compound is one of the key aspect for optimized durability. Dedicated experiments and theoretical framework based on fracture mechanic are needed for this purpose. The presented activity proposes the fracture toughness characterization of copper-resin interface in a power semiconductor package. Double Cantilever Beam (DCB) test has been executed on dedicated bimaterial coupon with an initial crack at interface. The aim of this test has been to enhance the fracture propagation mode-I (opening). Strain energy release rate (SERR) and mode-mixity have been estimated from this experiment developing a finite element analysis that is able to predict the crack length during the experimental DCB trials and to predict the energy release rate by virtual crack closure technique (VCCT). Mode-mixity has been estimated collecting displacements near the crack tip by crack surface displacement method (CSD). The proposed methodology for fracture toughness characterization represents a strong pillar to predict fracture behavior due to any load conditions and it is needed to describe interface adhesion by cohesive zone method (CZM)
Material Characterization and Warpage Modeling for Power Devices Active Metal Brazed Substrates
No full textThe metallized insulating substrates work as mechanical supports for the circuitry of Power Module Packages. Due to their specific functions, substrates for power electronics are made by different materials. The conductive metal layers can assume different functions: the top metal serves as power circuitry routing while the bottom metal improves the mechanical robustness and thermal efficiency. Ceramic layer provides excellent electrical insulation. These features play an essential role in the operation of power modules, which are often operated at high voltage and high current density. The substrates, composed by materials with different thermal expansion coefficients, are subjected to cyclic stresses due to temperature variations induced by operative working conditions. The substrate layouts typically include differences in shape and/or thickness between the top and the bottom side; this generates asymmetrical distributions of stress/strain resulting in overall warpage. The variations of this warpage induce mechanical fatigue during lifetime and represent a limiting factor for reliability. The scope of the presented work is the characterization of the out of plane warpage of Active Metal Brazed substrates (AMB) by means of numerical approach. The elastoplastic properties of metal and ceramic have been measured, evaluating the thermal softening of the copper as well. These characteristics are needed to calculate AMB warpage through Finite Element Models (FEM), simulating the warpage induced by a passive temperature cycling. Warpage computed from numerical model have been benchmarked and validated with optical warpage measurements. The validated numerical model has been developed to optimize the substrate warpage variation during cycling improving the whole package reliability
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