1,720,959 research outputs found
Diode-pumped laser operation of Pr3+:Ba(Y0.8Lu0.2)2F8 in the visible region
No full textWe report on, to the best of our knowledge, the first growth, spectroscopy, and laser operation of monocrystalline Ba(Y0.8Lu0.2)2F8 doped with 1.25 at.% of Pr3+ ions (Pr:BYLF). We studied the spectroscopic properties of this material, particularly in comparison with its isomorph Pr3+ : BaY2F8 (Pr:BYF). Under diode-pumped excitation, we achieved continuous-wave laser operation in the orange, red, and deep red regions in the three possible crystal orientations. We obtained considerably improved laser performances and remarkably low passive losses, in comparison with Pr:BYF crystals and other fluorides, indicating that Pr:BYLF is an excellent host material in the visible region
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Smart and cheap scale for estimating live-fish biomass in offshore aquaculture
No full textAt present, technological support may specifically contribute to develop and to improve the aquaculture production, and in particular the fish production in offshore pens. Estimating live-fish biomass is extremely relevant to optimize the whole growth cycle, therefore the availability of portable and reliable scale is very important. We present here the detail of a smart scale suitable to be used over a rolling and pitching ship either on lakes or seas
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Spectroscopy and diode pumped laser emission in (Lu<inf>x</inf> Gd<inf>(1-x)</inf>)<inf>3</inf> Ga<inf>5</inf>O<inf>12</inf>:Tm<sup>3+</sup> single crystal
No full textWe report on the first laser emission of (Lux Gd(1-x))3 Ga5O12 doped with Tm3+ ions obtaining a slope efficiency of 20% and a maximum output power of 170 mW centered at 2013 nm. Evidences of a multiline emission are shown. Moreover a spectroscopic investigation on six samples of (Lux Gd(1-x))3 Ga5O12:Tm3+ having different Lu concentrations is presented. In particular the stark sublevels energy of 3H6 and 3F4 manifolds have been determined. Spectroscopic data have been utilized to calculate absorption and emission cross sections and gain curves
Widely tunable, efficient 2 μm laser in monocrystalline Tm3+:SrF2
Get PDFWe report on the growth, spectroscopy, and laser operation of monocrystalline Tm3+:SrF2. Spectroscopic investigations confirmed the presence of broad absorption and emission bands caused by inequivalent doped sites, introduced by charge compensation e ects which also caused the clusterization of doping ions in the lattice. We obtained continuous-wave laser emission at about 2 μm, with e ciencies comparable with other Tm-doped crystals. We also achieved an uninterrupted tuning range of 180 nm between 1.8 and 2 μm. This characterization indicates that SrF2enhances the cooperative mechanisms between Tm ions, helping to obtain remarkable laser performances at low doping concentrations
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