1,721,057 research outputs found
Supplemental Material, NM_NT_SI_rev - C-Si hybrid photonic structures by full infiltration of conjugated polymers into porous silicon rugate filters
No full textSupplemental Material, NM_NT_SI_rev for C-Si hybrid photonic structures by full infiltration of conjugated polymers into porous silicon rugate filters by Valentina Robbiano, Salvatore Surdo, Alessandro Minotto, Giancarlo Canazza, G Mattia Lazzerini, Shabbir M Mian, Davide Comoretto, Giuseppe Barillaro, and Franco Cacialli in Nanomaterials and Nanotechnology</p
Highly oriented poly(paraphenylene vinylene): Polarized optical spectroscopy under pressure
No full textWe investigate the role of intermolecular interactions in thick highly oriented poly(p-phenylene-vinylene)
under applied hydrostatic pressure by polarized reflectance and Raman spectroscopy. Evidence of intramolecular
and intermolecular effects is observed. The analysis of the C=C stretching modes and of the optical
transition at about 3.7 eV previously assigned to conjugation chain ends indicates that the conjugation length
of this highly ordered polymer is weakly affected by the applied pressure. On the other hand, the absorption
onset and the spectral shape of the vibronic progression are deeply influenced by pressure, which generates a
bathochromic shift joined to a broadening of all the optical transitions. By analyzing the data with a suitable
optical model for an anisotropic system, a significant difference between the optical components polarized
parallel and perpendicular to the stretching direction is observed. For the parallel component, a low energy gain
of the oscillator strength, joined to a correspondent reduction in the high energy spectral range, is observed. For
the perpendicular component, an increase in the oscillator strength is instead observed for all wavelengths.
These effects are mainly assigned to intermolecular interactions even though a contribution from electronphonon
coupling cannot be excluded to explain the observed broadening
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
Nonlinear optical response of a polycarbazolyldiacetylene film through femtosecond two-photon spectroscopy
No full textWe report the two-photon absorption (TPA) spectrum of a polycarbazolyldiacetylene film in the interval 900–1550 nm. In this range, the TPA coefficient exhibits a broad peak with a maximum of 33 cm/GW around 1125 nm, which indicates a two-photon state positioned at 2.2 eV, slightly below the one-photon state at 2.36 eV. The magnitude of the nonlinear refraction in the infrared is predicted on the base of a Three Level Model, which accounts fairly well for the nonlinear absorption in the explored range
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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