1,721,058 research outputs found
Y. H. Toivonen 60-vuotias
No full textHommage à Y. H. Toivonen à l'occasion de son soixantième anniversaire (ranska
Detailed kinetic analysis of Shay chloroleukaemia cell population propagated in permanent suspension culture in vitro
No full textDetailed kinetic analysis of a growing cell population is difficult, even when assay conditions are nearly ideal. Therefore, it is usually essential to perform several types of experiments and analyse all the results in terms of a mathematical model, the use of which is not limited a priori by a specified application. In the present study we investigated cell population kinetics using rat chloroleukaemia cells propagated in suspension culture in vitro. The parameters were measured: doubling time of the population, fraction of labelled mitoses, changes in labelling index with time after pulse labelling, continuous labelling and stathmokinetic index. Analysis of the results was based on a computer program CECAM, which is a stochastic model capable of simulating essentially all types of kinetic experiments based on presently known assay techniques. The results showed that precise and reliable information on cell population kinetics could not be obtained from the analysis of any single type of experimental data. In particular, the technique of labelled mitoses underestimated the duration of the G1 phase, owing to subtle label-induced changes in population behaviour. The changes could not have been detected with any certainty without rigorous quantitative comparisons with other types of experimental data. As a whole, however, results obtained by the different techniques were in agreement and the kinetic behaviour of chloroleukaemia cells in vitro could be established in detail. In certain circumstances even minute changes in the kinetic parameters of the cells can modify population behaviour drastically. To study these cases adequately the experiments must be designed with utmost care, preferably with the aid of preceding simulations. This is because demonstration of small primary changes in population kinetics may be beyond the limit of detection of any single assay method
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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