1,721,011 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
Study of the spatial distribution of free radicals in ammonium tartrate dosimeters through pulsed ESR techniques.
No full textContinous wave and pulsed EPR analysis of spatial distribution of free radicals in ammonium tartrate samples.
No full textSpin trapping as tool for investigating radiation induced free radicals in biologically active molecules
No full textSince from the second half of the last century the spin trapping has found wide applications in
chemistry, biology and medicine [1]. Of particular interest are the studied of the free radicals induced
in biologically active molecules, such as DNA and proteins, when they are exposed to ionizing
radiation. Their characterization allows to investigate the radiation-induced primary processes inside
living cells. Indeed, ionizing radiations produce many kinds of free radicals through direct action;
radicals can be formed also by indirect actions. However, the direct detection of these radicals is hard
to obtain as they have a too short lifetime and this makes difficult to record them by conventional
electron spin resonance (ESR) technique. This limitation can be overcome by means of spin-trapping
method wherein these short-lived free radicals are converted using a diamagnetic scavenger (the
spin trap) to longer-lived radicals (the spin adducts), which can be conveniently investigated by means
of ESR.
Here, we review a combined method of ESR and spin trapping to identify free radicals induced by
direct ionization as well as OH-radical reactions in nucleic-acid related and protein-related
compounds. ESR combined with spin trapping remains a useful method for clarifying these processes
in a living organism
Defects in graphenic materials by EPR and DFT methods
No full textWe have used EPR to characterize a series of defects, which are characterized by tipical g-tensors, linewidths, intensity as function of the temperature. Mostly, signals arises from the presence of conduction electrons, and of so-called "edge states", that are unpaired electrons located at the edges of graphenic flakes; the relative molecular orbitals are not very muche extended as for low-lying orbitals, and are located within few atomic rows from edges with zig-zag topology. All the relative EPR signals are naturally and intrinsically generated by all graphitic materials. We now extend our study to the defects that are formed inside the graphenic structure. There is a full zoo of possible defects that can in principle originate EPR signals, like the presence of ad-atoms, holes, dislocation of atoms.We have started to study and analyze each type of defect from an experimental as well as from a theoretical point of view
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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