1,721,003 research outputs found
Writing and Erasure of Holographic Gratings in Dye-Doped Polymer Dispersed Liquid Crystals
No full textPolarization holographic techniques: a method to produce diffractive devices in polymer dispersed liquid crystals
No full textSpectrograph Based on a Single Diffractive Element for Real- Time Measurement of Circular Dichroism
No full textIn this study, a novel and simple diffractive spectrographic method for
real-time measurements of circular dichroism (CD) is considered from a
theoretical and experimental approach. A demonstrator prototype of the
CD spectrograph has been developed and its performance has been
compared with a commercial phase-modulation CD spectrometer. The
main element of the device is a polarization holographic grating, recorded
in a thin photosensitive organic film, by two interfering opposite circularly
polarized beams. A peculiarity of this grating is that the amplitude of the
þ1 (1) order of diffraction is proportional to the right (left) circular
polarization component of the incoming beam. Here we demonstrate that
the CD spectrum of a specimen can be easily evaluated from the intensities
of the diffracted beams. A white light beam passing through the specimen
is diffracted from the grating and the intensities of the 6 1 orders of
diffraction are measured. Due to the spectral selectivity of the grating, the
CD at each wavelength can be evaluated at the same time using two linear
array detectors
Light-induced molecular adsorption and reorientation at polyvinylcinnamate-fluorinated/liquid-crystal interface
No full textWe have carried out a detailed experimental study, by means of x-ray reflectometry (XRR) and half-leaky
guided mode (HLGM) optical characterization, of the light-induced molecular adsorption and reorientation at
the polyvinylcinnamate-fluorinated (PVCN-F)/liquid-crystal (LC) interface of a LC cell doped with the azodye
methyl red (MR). The XRR data allowed characterizing the microscopic structure of the adsorbed dye
layer both before irradiation (dark adsorption) and after irradiation (light-induced adsorption). The HLGM
optical characterization has made possible the experimental determination of the nematic director profile in the
LC cell and evaluation of the effects of light-induced adsorption on the LC anchoring conditions. The experimental
findings have confirmed the formation of a dark-adsorbed layer and are in agreement with the absorption
model previously proposed to account for the complex phenomenology related to light-induced anchoring
and reorientation in dye-doped liquid crystals
Polymer-dispersed liquid crystals: effects of photorefractivity and local heating on holographic recording
No full text
Reply to “Comment on ‘Optical determination of flexoelectric coefficients and surface polarization in a hybrid aligned nematic cell’ ”
No full textIn their Comment [G. Barbero and L. R. Evangelista, Phys. Rev. E 68, 023701] on our paper [A. Mazzulla, F. Ciuchi, and J. R. Sambles, Phys. Rev. E 64, 021708 (2001)], Barbero and Evangelista conclude that the procedure followed by us to fit the reflectivity data from the half leaky guided mode technique is questionable. In the absence of a model that is able to reproduce the experimentally obtained tilt angle profiles, their argument is unsubstantiated. To further refute their arguments, we also illustrate and discuss additional experimental data (that were not shown in our paper) that strongly support our conclusions
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
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