1,720,969 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
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
Ischaemia/reperfusion in the posthypoxaemic re-oxygenated myocardium: haemodynamic study in the isolated perfused rat heart
No full textIn order to study the haemodynamics of reperfusion injury in the posthypoxaemic heart, we exposed buffer-perfused isolated rat hearts to either: (1) 20-minute low-flow ischaemia or (2) 20-minute hypoxaemia followed by re-oxygenation and further ischaemia/reperfusion. In group 2, the myocardial contractility recovered less (p < 0.002) than in group 1. This model therefore represents with sufficient reliability the clinical situation where hypoxaemic hearts are re-oxgenated before ischaemia/reperfusion and receive more severe injury than hearts exposed to ischaemia/reperfusion only. To locate the major site of the injury, further data were obtained (1) with infusion of superoxide dismutase and catalase during hypoxaemia and in the first five minutes of re-oxygenation, and (2) by eliminating re-oxygenation. It appears that the major determinant of reperfusion injury in hypoxaemic hearts is to be looked for in the events underlying hypoxaemia or re-oxygenation, and is mediated by oxygen-derived free radicals
HUMAN RED-BLOOD-CELL AGING AT 5,050-M ALTITUDE - A ROLE DURING ADAPTATION TO HYPOXIA
Full text linkTo test the hypothesis that the human red blood cell aging process participates actively in the adaptation to hypoxia, we studied some physical and biochemical hematologic variables in 10 volunteers at sea level (SL) and after 1 (1WK) or 5 wk (5WK) of exposure to 5,050-m altitude. The 2,3- diphosphoglycerate-to-hemoglobin ratio (2,3-DPG/Hb) was 0.88 ± 0.03 (mol/mol) at SL and increased to 1.08 ± 0.03 (P = 0.002) and 1.28 ± 0.05 (P < 0.0001) at 1WK and 5WK, respectively. The average red blood cell density (D50), which is inversely proportional to the fraction of young red blood cells and is therefore an index of the red blood cell aging process, was 1.1053 ± 0.0007 g/ml at SL and decreased to 1.1046 ± 0.0008 g/ml (NS) and 1.1018 ± 0.0008 g/ml (P < 0.0001) at 1WK and 5WK, respectively. D50 was correlated with 2,3-DPG/Hb at SL (P = 0.004), only weakly at 5WK (P = 0.1), but not at all at 1WK. The arterial O2 saturation was correlated with the change of 2,3-DPG/Hb in 1WK (P = 0.02) and that of D50 in 5WK (P = 0.04). It is concluded that short-term (1WK) increase of 2,3-DPG/Hb is not associated with the erythropoietic response but is presumably due to respiratory alkalosis. By contrast, after prolonged hypoxia (5WK), erythropoiesis may provide an efficient way for increasing blood 2,3-DPG through an augmented proportion of young red blood cells
- …
