1,720,964 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
The nitric oxide metabolism in the hypoxic, ischemic and reperfused human skeletal muscle cell: clinical and therapeutical observations
No full textBACKGROUND: The biochemical and metabolic role played by nitric oxide (NO) in course of oxidative stress due to cell hypoxia, ischemia and reperfusion has a determinant relevance in the mitochondrial adaptive changes which antagonize the irreversible morpho-functional damage. In particular conditions, such as in prolonged ischemia and/or exogenous NO supplementation, this element is present in the radical form (NOO*) concurring to peroxidative cell injury. Aim of this study was to investigate these opposite NO aspects in hypoxic, ischemic and reperfused human skeletal muscle tissue. METHODS: Skeletal muscle samples were taken during elective knee orthopedic surgery in 10 consecutive patients. The biopsies were obtained before, after 5+/-1 min and 58+/-2 min from tourniquet application and then after 18+/-3 min following muscle reperfusion. The samples, immediately frozen in liquid nitrogen, were assayed for endocellular free NO following the gas-amperometric method described by Palmerini C. RESULTS: When compared with normoxic tissues, a significant decrease in free NO content was observed in hypoxic samples. After about 60 min of prolonged ischemia the NO levels show an evident increase, while the tissue reperfusion leads to a progressive restoration of physiological content in the cellular free nitric oxide. CONCLUSIONS: The obtained data in hypoxic muscle cell seem to underline the pivotal role played by NO in adapting the cytochrome c oxidase oxidative activity to lower O2 bio-availability. On the other hand the prolonged ischemia leads to a consistent NOO* generation triggered by oxyradical generation and Ca2+ intracellular over load. Even if the tissue reoxygenation restores the normal NO levels it is arguable that the pre-treatment of ischemic cell with antioxidants, Ca-antagonist and Dexamethasone supplementation could represent a crucial and specific therapeutic approach to critically ill patient
Biochemical and metabolic aspects of oxyradical pathology in the hypoxic-ischemic reperfused human skeletal muscle tissue. Clinical markers and therapeutic approach
No full textBACKGROUND: Following our previous studies on the biomolecular and biochemical aspects of the human tissue oxidative damage due to hypoxia, ischemia and reperfusion, aim of the present work is to evaluate the role played by oxyradical generation in the morphofunctional cellular injury. We evaluated the tissue levels of some metabolic markers (MDA, Catalase, Uric Acid) to obtain a pathogenic picture and then a therapeutic approach closely related to the cellular biodynamics. METHODS: A skeletal muscle samples were taken during elective knee orthopedic surgery in 20 consecutive patients. The biopsies were taken in normoxic conditions and after 5 +/- 1 and 62 +/- 3 min form tourniquet application and finally 21 +/- 2 min following muscle reperfusion. The samples were assayed for tissue Malondialdeyade (MDA), uric acid and catalase (CAT) contents with HPLC and fluorimetric procedures. All data were evaluated in terms of computerized statistical analysis. RESULTS: When compared to normoxic tissue (1.24 +/- 0.26 nmoli.mg-1 protein), the MDA levels show a moderate increase in hypoxic (1.66 +/- 0.12) and ischemic tissue (1.78 +/- 0.13), while highly significant is the rise in reperfused muscle MDA content (5.94 +/- 0.15). The uric acid as far as CAT shows no appreciable alterations in hypoxia and ischemia. Following reoxygenation an increase in uric acid contents with a concomitant CAT tissue consumption appear evident. CONCLUSIONS: The obtained data seem to underline the cytoprotective role played by adaptive changes in the hypoxic and ischemic human cells. On the contrary, the rapid reoxygenation of the ischemic tissue appears to start oxyradical neo-generation. In clinical and therapeutic terms these observations underline a peculiar and different approach to the critically ill patient
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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