1,721,156 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
Arcipelago delle maree. Esplorare gli incerti confini della Venezia anfibia
No full textIl contesto geografico di Venezia e della sua laguna, con le peculiari fisionomie
insulari, è tra i sistemi ambientali e urbani più studiati al mondo. Le zone umide
costiere, le lagune e le isole sono state a lungo considerate spazi soglia in cui
terra, cielo e acqua si incontrano in dinamiche condizioni di materialità. Per
apprezzare la molteplicità di significati e la produzione di conoscenza ricavate
da questi ambienti anfibi, dobbiamo comprendere non solo la politica e le grandi
narrazioni, ma anche memorie personali, riflessioni, tradizioni locali e pratiche
vernacolari.
Il libro raccoglie la traduzione dall’inglese di un numero speciale dedicato
a Venezia e laguna, uscito nel 2021, per la rivista scientifica internazionale
di studi insulari Shima. L’argomento affrontato prendeva in considerazione
Venezia e il suo intorno lagunare, come un congiunto territoriale ibrido in cui
la continua mutazione, trasformazione e negoziazione ne fanno il carattere
distintivo. Un ‘cyborg-paesaggio’ dove i limiti tra natura e cultura, acqua e terra,
assenze e presenze, affollamento e desolazione sono precari e incerti, nonché
continuamente da negoziare e discutere. Questo è il punto di partenza per
cogliere la complessità locale e la marginalità di queste aree di transizione,
comunque in grado di richiamare ed evocare temi globali e opportunità
transdisciplinari
Regiochemistry of propene insertion with group 4 polymerization catalysts from a theoretical perspective
No full textThe regiochemistry of monomer insertion in propene polymerization promoted by group 4 metal catalysts has been investigated by using DFT methods. Our study supports the concept that for metallocene-based catalysts the regiochemistry of propene is mainly originated by steric effects. Instead, for octahedral systems a delicate balance between steric and electronic effects is found. This allows to play with the electronic properties of the ligand framework to tune finely the regiochemistry of polymerization
Molecular Modeling of the Regiochemistry of Olefins Insertion with Single Site Polymerization Catalysts
No full textThe regiochemistry of propene insertion promoted by metallocene and postmetallocene Column 4 metal catalysts is investigated with quantum mechanics techniques. It is shown that steric effects dominate the regiochemistry of monomer insertion with classical metallocene-based catalysts, whereas both electronic and steric effects contribute to the regiochemistry of propene insertion with postmetallocene catalysts
Living Propene Polymerization with Bis(phenoxy-imine) Group 4 Metal Catalysts: A Theoretical Study
No full textBis(phenoxy-imine)Ti catalysts with ortho-F-substituted phenyl rings on the N can promote living propene polymerization. On the basis of DFT calculations, it has been proposed that the “living” behavior originates from an unprecedented attractive interaction between the aforesaid ortho-F atoms and a β-H of the growing polymer chain, which would render the latter less prone to being transferred to the metal and/or to the monomer. In this paper, we report on a thorough full-QM and combined QM/MM investigation of representative model catalysts, demonstrating that the key factor is instead the repulsive nonbonded contact of the F-substituted rings with the growing polymer chain and an incoming propene molecule, which destabilizes the sterically demanding 6-center transition structure for chain transfer to the monomer. A conceptually similar substituent effect has been reported before for several metallocene and nonmetallocene catalysts
- …
