1,720,978 research outputs found
Orientational gratings in dye-doped polymer-dispersed liquid crystals induced by the photorefractive effect
No full textPolymer stabilized Monodispersed Liquid Crystal Droplets: Microfluidics Generation and Optical Analysis
No full textLiquid crystal droplets are widely used in optics
and photonics applications. They can act as simple
resonators or be arranged in interconnected periodic con-
gurations when their external dimension are similar. In
this work we optically analyze and describe the microuidic
generation of liquid crystal droplets in a thermally stabilized
environment, namely water, which enables a narrow
droplets diameter distribution. We demonstrate a ne
control of the droplet dimensions in both nematic and
isotropic phases by controlling the ratio between liquid
crystal and water ows. Droplets generated in the isotropic
phase show a complex internal structure which reects
their high degree of internal disorder. Moreover, the internal
conguration of the droplets also depends on the
purity degree of the water in which they grow. In order to
investigate their size distribution and their internal structure,
a small amount of photo-polymerizable agent (NOA61
optical glue) was added to the liquid crystal to stabilize the
droplets structure and to avoid their coalescence. Acting
this way, polymer stabilized liquid crystal droplets were
created after light induced polymerization, which are stable
even after water evaporation. The polarized microscope
analysis shows that the bipolar or radial order of the
liquid crystal is still preserved inside the droplets depending
on the water purity. Moreover an improved size uniformity
is reported
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
Famotidine in the short-term treatment of duodenal ulcer and of concomitant peptic lesions : comparison with cimetidina
No full textAppropriate 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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