1,720,981 research outputs found
The integration of chalcogenide materials with nanophotonic circuits for recongurable control of light
No full textThis thesis aims to develop a new conceptual approach for programmable nanophotonic devices, by combining the silicon photonics platform with lowloss phase change materials (PCMs). The approach brings together silicon photonics and phase change technology into a hybrid platform. Digital patterns of pixels are written in the phase change layer using an optical pump laser, which shapes the flow of light by weakly perturbing light transport in the hybrid photonic waveguide. The advantage of this approach is that once set, the phase change materials are self-holding and therefore passive operation would be possible, all at an unparalleled device foot print. Traditional phase change materials were tested for this application but were found to have an intrinsic absorption loss that prevented their use, as any guiding effects were offset by the lower total transmission. Therefore, in order to achieve the goals set out in this thesis, an entirely new material platform was needed. A large part of the efforts in this project involved the development of a new family of optical phase change materials with ultralow losses. Sb2Se3 was selected as the most suitable material and integrated into a range of photonic devices to characterize the optical and electrical properties before finally realizing a reconfigurable wavefront shaper based on an MMI design. With transmission losses of 100 dB/cm for a straight waveguide clad with 25 nm of crystalline Sb2Se3, this represents the lowest loss PCM available, whilst still maintaining a sizable refractive index shift between the amorphous and crystalline phases of ∆n=0.77. A reconfigurable router was demonstrated, capable of reversibly switching the output between two waveguides using a pixel pattern of Sb2Se3 distributed in a layer above an MMI. The results in this thesis are the first of their kind and clearly demonstrate the viability of the conceptual approach of freeform patterning of the flow of light using an ultralow-loss phase change material. This work is an initial step towards the development of fully programmable low-loss integrated photonic devices, allowing for optical routing within larger circuits to be realized. This will open up the possibility of low loss, on-chip wavefront shaping applications such as mode converters, neuromorphic computing and LiDAR.<br/
Dataset for A new family of ultra-low loss reversible phase change materials for photonic integrated circuits: Sb2S3 and Sb2Se3
No full textDataset supports the paper
Matthew Delaney Ioannis Zeimpekis Daniel Lawson Daniel W. Hewak Otto L. Muskens (2020) A New Family of Ultralow Loss Reversible Phase‐Change Materials for Photonic Integrated Circuits: Sb2S3 and Sb2Se3 Advance Functional Materials
DOI:https://doi.org/10.1002/adfm.202002447</span
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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