1,720,976 research outputs found
Determination of ethanol content in wine through a porous silicon oxide microcavity
No full textThis paper reports on a new sensor, based on a porous silicon oxide microcavity, for the determination of the alcoholic strength of white and red wines. The shift of the cavity mode due to interaction with ethanol is monitored in continuous way by means of Fourier transform infrared (FT-IR) spectroscopy comparing the data obtained in condensation and evaporation mode. The results demonstrate the advantage of working in evaporation mode and the possibility to determine the alcoholic strength of wine with a good reproducibility and selectivity
Free carriers reactivation in mesoporous p+-type silicon by ammonia condensation: an FTIR study
No full textThe influence of ammonia, in the range of temperatures from ≈100 K to ambient, on the IR spectrum of p+-type silicon (60% porosity) has been investigated. In contrast with the case of NO2 [1], interaction with NH3 at low pressures and room temperature does not cause any reactivation of carriers (as monitored by the loss of transparency in the IR). Extensive reactivation is instead observed at low temperatures and high NH3 pressures, the sample becoming strongly opaque below 2000 cm-1. When the temperature rises, ammonia is outgassed and the original transparency is restored. Ammonia is an electron-donor molecule, so in principle chemisorption could occur, but plays no role in reactivation, in contrast with the NO2 case. The findings, resembling those reported for polar liquids wetting p+-type PS, are explained on the basis of dielectric effects [2]: the observed loss of transparency is related to the presence of a high-density gas filling the pores, possibly in a sort of supercritical state or at the most physisorbed on the walls
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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