1,720,960 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
Raman analysis and mapping for the determination of COOH groups on oxidized single walled carbon nanotubes
No full textRaman spectroscopy and mapping, coupled to molecular labelling, is used to analyse and
monitor the first stage of carbon nanotube functionalization, i.e. their oxidation, which
is usually performed to increase the number of surface carboxylic groups, allowing both
a better dispersion in solution and the further attachment of biomolecules. Since the abundance
of such surface groups is critical for the final application, it is important to develop a
reliable but simple and fast method to investigate their presence on the tube walls. The presented
data demonstrate the correlation between the presence and intensity of the Raman
peak ascribed to the labelling molecule and the production of COOH groups on the nanotube
walls. Between the analysed carbon nanotubes related spectral parameters, the G0
Raman peak position appears to be the most sensitive one to determine the degree of single
walled carbon nanotube labelling, which directly depends on the number of COOH groups
available for molecular attachment, i.e. on the efficiency of the oxidation treatment.
The presented results demonstrate that it
is possible to directly use the Raman signal of the THA labelling
molecule for the COOH groups determination. In particular,
the labelling is extremely useful to overcome the
limitations of Raman spectroscopy alone in determining the
degree of oxidation, so that such a method can be applied
to study the oxidation itself, with particular reference to its
efficiency and to the analysis of the presence of carbonaceous
impurities (fulvic acids residues) in acid treated SWCNT samples. We are presently working in this direction, also
applying the THA-method to monitoring different oxidation
techniques, such as microwave and plasma treatments
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
A sensitive and practical fluorimetric test for CNTs acidic sites determination
No full textA sensitive and practical colorimetric test for oxidized carbon nanotubes (CNTs) is described. The assay is based on direct labeling with the commercially available fluorescent dye thionin acetate (THA). This strategy offers the possibility for quantitation of acidic sites in a very fast and easy way. Since the abundance of carboxylic groups, which increases with treatment time, temperature and the degree of lattice defectiveness, is critical for the final application, it is important to determine the prevalence of surface acidic groups. However, there are some difficulties associated with monitoring the oxidative reaction. Although a number of analytical techniques such as IR, Raman and XPS have been applied to address these shortcomings, a routine monitoring tool without the need for specialized hardware has been difficult to find. Some groups have reported acid–base titration of acidic sites of different CNTs; however, these techniques suffer from several shortcomings: (i) CNTs must be properly dispersed in the aqueous solution; (ii) they do not meet the requirements of a fast routine test, because they are multistep sequences. In the present communication we report experiments on the use of fluorescence labelling reactions for acidic group determination on CNTs. It is a very sensitive, practical, fast and accurate method to titrate carboxylic groups on carbon nanotube samples based on their specific interaction with a cationic dye such as thionin. The specificity of the interaction is supported by Raman spectroscopy and thermogravimetric analysis. The method is particularly useful as a routine test to monitor the oxidation processes of both single and multiwalled CNTs
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