1,720,958 research outputs found
Experimental demonstration of 10 Gbit/s, 4.7ps pulse transmission over 4300km in a low dispersion, loss compensating dispersion decreasing fibre
No full textWe describe recent results on the fabrication of low dispersion, loss compensating dispersion decreasing fibres and report their use in long distance, ultrashort pulse transmission experiments. Error-free propagation of 10 GBit/s, 4.7ps pulses over 4300km of such fibre is demonstrated illustrating the benefits of the reduced dispersion range achieved
Periodically amplified transmission system based on loss compensating dispersion decreasing fibre
No full textAmplified transmission lines based on loss compensating dispersion decreasing fibres (LCDDFs), i.e. fibres in which the dispersion profile is made to follow that of the fibre loss, are a promising medium for the transmission of high bit-rate, ultrashort soliton pulses. Due to the perfect match between nonlinearity and dispersion at all points in the fibre LCDDFs provide access to propagation regimes (both single channel and WDM) made inaccessible by the periodic amplification process in systems based on conventional dispersion shifted fibre (DSF). To date soliton loss compensation has only been demonstrated in single pulse, single span propagation experiments. In this presentation, we describe the first experimental demonstration of a periodically amplified transmission system based on LCDDFs. We report error free transmission of: (a) 10 Gbit/s, 6.5ps pulses over 8 amplification cycles (304km) for a system with a mean dispersion of 2.4ps/(nm.km) and 38km amplifier spacing, L). The results indicate the potential of the technique to enter propagation regimes made inaccessible by conventional average soliton techniques. The measurements also highlight the limiting effect of the soliton acoustic interaction which can be severe in these types of system, in which the minimum realistically achievable RMS path average dispersion tends to be higher than that of a conventional DSF system. The limiting effects of third order dispersion are also observed
All-optical modulation of 40GHz beat frequency conversion soliton source
No full textThe authors report the first error-free direct optical modulation of 40GHz pulses generated by a low-jitter beat frequency to soliton train conversion source
Periodically amplified system based on loss compensating dispersion decreasing fibre
No full textWe demonstrate for the first time to our knowledge the use of loss compensating, dispersion decreasing fibre (LCDDF) in a periodically amplified transmission system. The significant limiting effects of the soliton acoustic interaction and third order dispersion are observed and discussed. The results illustrate the potential of such techniques for extending data transmission to regimes forbidden by conventional average soliton dynamics
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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