1,720,969 research outputs found
Livelli di accumulo di 36 elementi in foglie di Quercus ilex nella città di Roma (Italia).
No full textCharacterization of mineral content in Quercus ilex leaves by photon and neutron activation analysis
No full textDetermination of iron isotopes by neutron activation analysis
No full textInstrumental neutron activation analysis has been applied to the determination of Fe isotopic abundances in iron materials with the experimental accuracy of 5%. The proposed method can be considered as a quite simple and fast quality check system on the iron isotope enriched oxides used as standard in Mössbauer spectroscopy. © 1995 Akadémiai Kiadó
The use of a radioactive tracer for the determination of distillation end point in a coke oven
No full textA novel high precision detection method for the determination of the distillation end point of the coking process (usually in the 950-1100°C range) has been developed. The system is based on the use of a metallic capsule that melts at a fixed temperature and releases a radioactive gas tracer (133Xe) in the stream of the distillation gas. A series of tests on a pilot oven confirmed the feasibility of the method on industrial scale. Application of the radioactive tracer method to the staging and monitoring in the coking process appears to be possible. © 1995 Akadémiai Kiadó
Deep inorganic fraction characterization of PM10, PM2.5, AND PM1 in an industrial area located in central italy by means of instrumental neutron activation analysis
Full text linkAtmospheric pollution is an important task in life sciences and, in particular, inorganic fraction characterization is considered as an important issue in this field. For many years, researchers have focused their attention on the particulate matter fraction below 10 μm: in this case, our attention was also focused on PM2.5 (i.e., particles with a size fraction smaller than 2.5 μm) and PM1 (below 1 μm). This paper would like to investigate whether the element accumulation in different granulometric fractions is similar, or whether there are behavior dissimilarities. Among the different analytical techniques, the instrumental neutron activation analysis, an instrumental nuclear method, was used for its peculiarity of investigating the sample without performing any chemical-physical treatment. Forty-two daily samples using the reference method were collected, 15 filters for PM10, 18 for PM2.5, and 12 for PM1; the filters, along with primary standards and appropriate standard reference materials, were irradiated at the National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) R.C.-Casaccia's Triga MARK II reactor. The irradiations carried out in the Rabbit and Lazy Susan channels allowed for the investigation of 36 elements and the relative Pearson's correlations between elements and PM-fractions (PM10 vs. PM2.5 was good, whereas PM10 vs. PM1 was the worst). The Enrichment Factors were studied for the three fractions to show how anthropogenic sources have affected the element content. A comparison between these data and element levels determined worldwide showed that our concentrations were lower than those determined in similar scenarios. Furthermore, a statistical approach (source discrimination, hierarchical cluster analysis, principal component analysis) has allowed us to identify similarities between the samples: the airborne filters can be divided in two main groups (i.e., one made of PM10 and PM2.5 filters and one only of PM1 filters), meaning a different element contribution to this fraction coming from other sources present at the site
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
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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