1,721,364 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
Comparing predictive ability in presence of instability over a very short time
Full text linkWe consider forecast comparison in the presence of instability when this
affects only a short period of time. We demonstrate that global tests do not perform well in this case, as they were not designed to capture very short-lived instabilities, and their power vanishes altogether when the magnitude of the shock is very large. We then propose and discuss approaches that are more suitable to detect such situations, such as nonparametric methods like the S test from Andrews (2003) or the MAX procedure from Harvey et al. (2021). We illustrate these results in a Monte Carlo exercise and in a comparison of the nowcast of the quarterly US nominal GDP from the Survey of Professional Forecasters (SPF) against a naive benchmark of no growth, over a period that includes the GDP instability brought by the COVID-19 crisis. We recommend that the forecaster does not pool the sample, but excludes the short periods of high local instability from the evaluation exercise
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
Patterns and symmetries in leaf development
No full textThe leaf is a coordinated mosaic of developmental domains, which are evident from leaf inception on the flanks of the apical meristem. The subdivision of the meristem into molecularly defined domains is regulated by the interactions of a number of gene products and by receptor kinase-mediated signals. The acquisition of symmetry axes in the emerging leaf is a process coordinated by hormones (such as auxin and cytokinins) and the expression of classes of genes (such as the knox and the ARP, as1/rs2/phan, genes). As with simple leaves, the architecture of compound leaves is defined by spatial/temporal gradients of regulatory gene functions: complexity results from the interplay between leaf differentiation processes and genes maintaining a partial level of indeterminacy in the developing primordium. Boundaries between regions with different molecular 'addresses' are considered, in plants as in Drosophila, as organizing centres for lateral organ development
Epoxide metabolites of opiates and their interaction with the hepatic microsomal epoxide hydrolase
No full textAppropriate 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
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