1,720,997 research outputs found
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
Surface repair: Self-replenishing functional polymer coatings
No full textPreviously, we reported a self-replenishing polymer surfaces which recover their lowsurface energy (i.e. hydrophobicity), upon surface damage[1]. Following up, we used a dual experimental-simulation approach to understand in-depth the surface segregation of low surface energy components[2], the self-healing mechanism involved on the surface recovery and the influence of different parameters (e.g. mobility of the polymer healing components) on the self-replenishing behaviour. Herein we report our further studies on self-replenishing structured-surfaces. The model self-replenishing polymer system was used to develop robust and easy processing hydrophobic surface-structured coatings, which are able to recover the low surface energy groups at new structured surfaces, created after damage
Self-healing adhesion on polymer coatings
No full textSupramolecular self assembling hydrogen bonded polymeric materials are of great importance due to its practical relevance. Well designed molecules based on these concepts can produce polymeric materials with \u93responsive\u94 properties like self healing even in coating application. The reversible, non-covalent hydrogen bonding interactions are a recurring design principle for these materials. Here, we report a concept for repairing mechanical damage at the coating/substrate interface. A dopamine based hydrogen bonded self-healing system was investigated and its use for self-healing adhesion purposes will be discussed. The presence of catechol bonds in the dopamine molecules promotes strong adhesion with the metal surface whereas flexible hydrogen bonding motifs ensure inter/intra molecular hydrogen bonding at the interface with polymer coating. The reversible character of the hydrogen bonds will ensure the repair of the adhesive bonds between the coatings and the substrate upon re-contact at the interface
Modelling of self-healing surface structures coatings
No full textFor many current engineering applications the performance of materials depends strongly on the surface properties of the top layer. In many cases a hydrophobic/superphydrophobic top surface is desired (for example for easy-toclean/ self-cleaning applications). The durability of coatings will be substantially extended if the layer which provides the hydrophobic/superhydrophobic property will have ability to self-heal. Previously, hydrophobic coatings with a self-healing surface were reported by our group. These coatings can recover a sufficiently high concentration of the lowsurface-energy groups at the air/polymer interface. The bulk material serves as reservoir of the low-surface energy component (fluorinated polymer dangling chains). A mechanism of self-replenishing involves the reorientation of the dangling chains which carry the fluorinated group. Silica particles where incorporated into the polymer system in order to introduce the surface roughness leading eventually to higher contact angles of the polymer coating. Our goal is to create a model of the a selfhealing superhydrophobic coating. In this work we use the mesoscopic modelling technique (dissipative particle dynamics) in order to study several aspects of these polymer/particle coating: 1) the segregation of the low surface energy groups at the top surface of the coating.; 2) the self-healing response of the system and 3) the dynamics and distribution of crosslinks in the polymer system in presence of relatively large silica particles. For these studies we considered the distribution of the low surface energy groups in a confined geometry at the interfaces available. The minimal thickness of the polymer layer which provides self-healing ability was also calculated. All the relevant parameters (crosslinking conditions, polymer precursor and dangling chain length and distance between particles) were changed systematically. The simulations give a valuable insight into the details of microstructures and dynamics and guide experiments towards the choice of the system with the maximal selfhealing efficiency
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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