1,720,966 research outputs found
Concentration and determinationof polycyclic aromatic hydrocarbons in aqueous samples on graphitized carbon black
No full textDetermination of Dichloromethane in Industrial Atmospheres and Emissions by Trapping on Light Adsorbence and Thermal Desorption
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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
Evaluation Tests and Applications of a Double Layer Tube-type Passive Sampler
No full textValidation tests on a thermally desorbable tube-type passive sampler filled with two different graphitized
carbon blacks were conducted in order to determine the influence of air velocity and direction,
concentration and sampling time on sampling rate. A specially made apparatus was used to study the
behaviour of the passive sampler in dynamic artificial atmospheres. This apparatus permits the simultaneous
sampling of 48 tubes at two different air velocities, minimizing errors due to random variations of the
operating conditions during a prolonged sampling time, which allows a better stochastic analysis of data to
be performed. The results were in agreement with those obtained by actively sampling the same test-tubes.
The results of laboratory and field tests showed that the behaviour of tube-type devices having a small
cross-section is independent of the environmental parameters checked over a wide range of operating
conditions. The constant sampling rate with these samplers in the range from 30 min up to more than 12 h
and the high sensitivity of thermal desorption methods allow the determination of organic species down to
the ppb level. A field experiment on the evaluation of the indoor pollution in a domestic environment is
also described. The use of a double-layer tube-type passive sampler, with the adsorbent of lower specific
surface area positioned at the exposed side of the device, allows a better desorption efficiency
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
Concentration and isolation of organic acids on graphitized carbon black
No full textThe application of graphitized carbon black to the extraction of traces of organic acids has been studied. It is demostrated that the recovery of these substances cannot be carried out without considering the nature of these compounds and their molecular structure. The amount of adsorbent and the kind of eluent required were deduced respectively from the breakthrough values and from distribution ratio
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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