1,721,140 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Overførsel af PFOS fra vand og græs til kvæg og får
No full textBaggrundFVST får i stigende grad henvendelser fra kommuner, organisationer og borgere vedrørende forurening af græs og vand med PFOS i områder nær tidligere brandsluknings-træningssteder. Der bliver efterspurgt måder at estimere PFOS niveauet i kvæg og får der græsser på området og/eller drikker af vandet. Denne opgave er udført med relativ kort svarfrist. Derudover er vores viden omkring kvæg og fårs optag og akkumulering af PFOS begrænset og principper er overført fra human toksikokinetik.KonklusionDer er foretaget nyere studier i kvæg og får omhandlende optag af PFOS fra vand og ensilage, som viser hvordan stoffet fordeles og udskilles i dyrene. For det første er angivet såkaldte transfer faktorer som siger noget om hvor meget PFOS der overføres fra vand/ensilage til serum (Tabel 1). Dernæst er der angivet fordelingskoefficienter for hvordan ratioen er mellem serum/plasma og fx muskelvæv I kvæg og får, som primært er det vi spiser (Tabel 2). Endelig er angivet fordelingskoefficienter mellem serum og mælk, sådan at PFOS niveauet i komælk kan estimeres (Tabel 3). Endelig har vi lavet et regneeksempel for hvordan man omregner fra PFOS niveau i drikkevand til PFOS niveauer i kød og mælk. PFOS optag i kvæg og får fra drikkevand og ensilage Der er for nylig udgivet et grundigt studie fra Australien (Drew et al. 2021), hvor optagelse af PFOS i kvæg og får fra kontamineret drikkevand er undersøgt. Studiet er kørt over lang tid, hvilket betyder at steady state er nået, og dette er vigtigt for datas pålidelighed. Resultaterne for PFOS viser at den såkaldte ’transfer factor’ dvs ratio mellem indholdet i serum relativt til indholdet i drikkevandet er 140 i voksent kvæg, som ikke er drægtigt og ikke er malkekvæg. For moderfår er den tilsvarende transfer faktor 20. Disse transfer faktorer gælder hvis dyrene har været eksponerede for det kontaminerede vand eller foder i mindst 3-5 halveringstider. Dette svarer til 222- 370 dage i kvæg (T½=74 dage) og 195 – 325 dage i får (T½=65 dage). Det er tilfældet i dette studie. Hvis dyrene har været eksponerede i kortere tid, vil transfer faktorerne være overestimerede
Variations on the Author
Get PDF“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
Get PDFWe 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
Get PDFWe 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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