1,721,075 research outputs found
Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs
No full textGregory M. Erickson, Peter J. Makovicky, Philip J. Currie, Mark A. Norell, Scott A. Yerby, Christopher A. Brochu (2004): Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs. Nature 430: 772-775, DOI: 10.1038/nature0269
Correction: Corrigendum: Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs
No full textGregory M. Erickson, Peter J. Makovicky, Philip J. Currie, Mark A. Norell, Scott A. Yerby, Christopher A. Brochu (2016): Corrigendum: Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs. Nature 531: 538, DOI: 10.1038/nature1648
Figure 2 in Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs
No full textFigure 2 Logistic growth curves for Tyrannosaurus and three related tyrannosaurids.Note that the exponential stages (the regions of maximal slope) are similar in duration but differ in slope (that is, growth rates). Regression equations (mass in kg, age in years) are as follows: T. rex, mass = {5,551/[1 + e‾0.57(age ‾ 16.1)]} + 5, r 2 = 0.953; D. torosus, mass = {1,728/[1 + e‾0.44(age ‾ 12.1)]} + 5, r 2 = 0.992; G. libratus, mass = {1,234/[1 + e‾0.38(age ‾ 12.4)]} + 5, r 2 = 0.950; A. sarcophagus, mass = {1,218/[1 + e‾0.43(age ‾ 14.1)]} + 5; r 2 = 0.985.Published as part of Gregory M. Erickson, Peter J. Makovicky, Philip J. Currie, Mark A. Norell, Scott A. Yerby & Christopher A. Brochu, 2004, Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs, pp. 772-775 in Nature 430 on page 774, DOI: 10.1038/nature02699, http://zenodo.org/record/373647
Tyrannosaurus Osborn 1905
No full textQuestions have been raised about the methods used and conclusions reached in this Letter 1. In revisiting the work, we realized that we did not provide sufficient methodological details regarding the many steps that went into our growth curve analysis, although the main conclusions of the paper were not affected. we regret any misunder- standing that might have resulted. A detailed rationale is available in the Supplementary Methods and Discussion of this Corrigendum and the source data are provided as Supplementary Data. we thank N. Myhrvold for bringing these issues to our attention. In our reanalysis we found a minor translational mistake affect- ing the reported growth for Tyrannosaurus, which does not appear to have contributed to Myhrvold’s concerns (details can be found in the Supplementary Methods and Discussion to this Corrigendum.) The correct equation is Mass = (5,649/[1 +e −0.55(Age−16.2)]) + 5. This produces a maximal growth rate of 758 kg yr −1 using points closely bounding the inflection point and 774 kg yr −1 using the instantaneous equation. The reported value was 767 kg yr −1. This slight discrepancy (see the corrected Fig. 2 in the Supplementary Methods and Discussion to this Corrigendum) does not compromise our conclusion that Tyrannosaurus primarily achieved gigantism through evolutionary acceleration.Published as part of Gregory M. Erickson, Peter J. Makovicky, Philip J. Currie, Mark A. Norell, Scott A. Yerby & Christopher A. Brochu, 2016, Corrigendum: Gigantism and comparative life-history parameters of tyrannosaurid dinosaurs, pp. 538 in Nature 531 on page 1, DOI: 10.1038/nature16487, http://zenodo.org/record/373650
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
- …
