1,720,984 research outputs found
Single photon emission from hydrogen-filled transition metal dichalcogenide bubbles
Full text linkSingle-photon emitters (SPEs) have been observed in strained single layers of Transition Metal Dichalcogenides (TMDs) at cryogenic temperatures. Several approaches have been investigated, but the achievement of regular arrays of controllably strained areas, and thus of controlled SPEs, remains a challenge. Here, we discuss the possibility of exploiting strained single-layered TMD bubbles containing highly pressurised hydrogen, which can be controllably created in an ordered fashion by lithography-based approaches. While these structures would deflate at cryogenic temperatures due to the liquefaction of hydrogen, we discovered that the deposition of few-layer-thick hexagonal boron nitride (hBN) on top of the TMD bubbles allows them to maintain their shape, even for temperatures as low as 5 K. By performing Raman measurements on the bubbles, we were able to track the strain behaviour of the system at different temperatures, showing that biaxial strains as high as 1.6% are achieved even at 5 K. Micro-photoluminescence (mu -PL) mu- PL) studies of hBN-capped WS2 bubbles at cryogenic temperatures demonstrated the presence of quantum emitters on the edges of several bubbles. The SPEs were characterised through magneto-mu -PL mu- PL and time-resolved measurements
Tailoring the optical properties of 2D transition metal dichalcogenides by strain
No full textAmong the ever-growing family of two-dimensional (2D) materials, those with semiconducting properties —chiefly transition metal dichalcogenides, or TMDCs— are of particular interest for photonic applications, specifically in the field of flexible optoelectronics. Thanks to their peculiar morphology, indeed, 2D materials can be stretched by various means, revealing the ability to withstand remarkably large mechanical deformations (elastic strains of up to 10%). In this work, we review the many striking effects of such deformations on the optical properties of TMDCs and related materials and present novel strategies to induce and control the strain on TMDC layers, which provide the blueprint for the realization of strain-tuneable, flexible photonic devices based on 2D semiconductors
Experimental Adhesion Energy in van der Waals Crystals and Heterostructures from Atomically Thin Bubbles
No full textThe formation of gas-filled bubbles on the surface of van der Waals crystals provides an ideal platform whereby the interplay of the elastic parameters and interlayer forces can be suitably investigated. Here, we combine experimental and numerical efforts to study the morphology of the bubbles at equilibrium and highlight unexpected behaviors that contrast with the common assumptions. We exploit such observations to develop an accurate analytical model to describe the shape and strain of the bubbles and exploit it to measure the adhesion energy between a variety of van der Waals crystals, showing sizable material-dependent trends
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
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