1,721,067 research outputs found
High-Quality Hydrogenated Amorphous-Silicon Carbon Layers as Obtained by a Particular Photochemical Vapor-Deposition Method
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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
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
Performances of epitaxial diamond in the field of X-ray diagnostics
No full textA thin epitaxial single crystal CVD (Chemical Vapour Deposited) diamond detector has been used in order to monitor the X-ray pulses coming out from a standard, portable, medical X-ray apparatus. The current pulses have been acquired and digitized in order to obtain the pulse shape, timing and dose. The obtained data were successfully compared with standard X-ray monitors like air ionization chambers and silicon detector arrays. The results strongly suggest a possible use of CVD epitaxial diamond in the field of X-ray diagnostics for energies up to 120 keV and doses up to 125 mGy and for X-ray pulse timing from 0.1 s or below and 2 s or more
Radiological X-ray dosimetry with single crystal CVD diamond detectors
No full textPulsed X-ray measurements have been carried out by using new single crystal epitaxial CVD diamond samples about 100 μm thick grown by microwave CVD in Roma Tor Vergata Laboratories on a 300 μm thick, low cost, HPHT diamond substrate. Both sandwich arranged and surface interdigitated contacts were used for the detectors in order to compare their performances. A standard X-ray radiological apparatus was used with maximum X-ray energies from 50 to 120 keV. Delivered doses were in the range between 0 and 50 mGy, with pulse duration times between 0.01 and 0.5 s were obtained either by using different time-integrated mAs products or, at a fixed value of mAs, by using different values of the bias voltage of X-ray generator. The linearity of the dose signal Q given by the integrated current with respect to dose recorded by ionization chamber Δ was checked by evaluating dose linearity index, i.e. the exponent in the equation Q = ADΔ. The values of Δ were very close to 1 (between 1.02 and 1.07) in the case of a fixed mAs product, while it was around 0.8 at fixed voltage in the range 50-120 kV. The response time of the detector as deduced from the tail of the pulse was between 15 and 20 ms. The reproducibility was very good among different series of measurements, with no memory or priming effect. These results suggest a strong and actually real possibility for diamond detectors to be used as solid state ionization chambers in radiology and for diagnostic purposes. © 2005 Elsevier B.V. All rights reserved
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