1,720,992 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
Impatto sui risultati a lungo termine dell'estensione della resezione distale dell'aorta negli interventi per dissezione di tipo A
No full textFast template preparation for molecular detection of Ralstonia solanacearum and Clavibacter m. sub sepedonicus in different samples
No full textMember states of EU conduct systematic official surveys to confirm in the potato production system the absence of Cms, casual agent of potato ring rot, and of Rs, casual agent of potato brown rot. The PCR test on DNA extracted from potato and processing water samples is the most frequently first screening test used among those regulated by EU Directives. The considerable amount of samples lots and the necessity of quick diagnosis results opens the need for a more rapid detection of these two bacteria with sensitivity comparable to the one of the official methods. Different type of samples artificially contaminated by 107 to 100 cfu/ml bacteria suspensions were processed by a preliminary additional centrifugation, to obtain crude extracts. Three methods also were then tested: i) lyses with 10% 0.5 N NaOH, ii) lyses plus purification on FTA TMCard (Whatman) and iii) digestion with amylase enzyme. The sensitivity of PCR, added with 2% blotto, on crude and on extracts treated with the above three methods was compared to PCR on DNA extracted by a commercial kit. The PCR detection limit on DNA extracted from potato and potato processing water by a commercial kit was respectively 103 cfu/ml and 104 cfu/ml. The PCR assays performed on crude extract of potato processing water showed a sensitivity increase to 102cfu/ml, whereas the PCR assays on potato samples lysated and purified on FTA TM card ii) showed the same sensitivity of official DNA extraction, permitting also to detect latently infected tubers
Analysis of kiwifruit bleeding sap: a useful method for early detection of Pseudomonas syringae pv. actinidiae
No full textThe bacterial canker of kiwifruit, caused by Pseudomonas syringae pv. actinidiae (Psa), became considerably important during last five years, after severe epidemics occurring from 2008/09 in central and northern Italy. The rapid spreading of the disease during last few years highlighted the need of a fast and sensitive method for the Psa detection in symptomless trees, to find possible inoculum sources and therefore limit the pathogen spreading. In this study we analyzed 51 samples of bleeding sap from asymptomatic trees of Actinidia deliciosa and A. chinensis collected in early spring 2012. The bleeding sap samples were used both for direct PCR assays and for bacteria isolations on NSA medium. The recovered Psa-like isolates were purified and characterized by the following biochemical tests: levan production, presence of oxidase, soft rot activity on potato disks, presence of arginine dehydrolase, hypersensitivity reaction in tobacco leaves (LOPAT) and fluorescence on King’s medium B; isolates were also assayed by PCR. Direct PCR assays on crude bleeding sap samples were able to detect the presence of the pathogen in three of the 51 tested samples, while the direct isolations detected the pathogen in six samples. Although more samples should be analyzed to evaluate the robustness of the method, analysis of kiwifruit bleeding sap may be a useful, rapid and sensitive tool for screening Psa-infected plants and/or to monitor the spreading of the pathogen in the fiel
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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