1,721,033 research outputs found
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
Fabrication of metasurfaces operating in the visible via nanotechnology and artificial intelligence
No full textThis thesis investigates the potential of flat optics as a solution to the problem
of bulky and expensive optical components in producing lightweight and
wearable optoelectronic devices. The research addresses scalability challenges
in structure fabrication, design of broadband operating devices, and increasing
operational and transmission efficiency in the visible range. It focuses
on the experimental part of the challenge. The study evaluates various design
approaches, including inverse designs using optimization techniques as
well as the use of machine learning algorithms. The thesis aims to explore a
path toward high efficiency, wide bandwidth, functional response, and scalable
fabrication in flat optics using semiconductor nanostructures. The results
demonstrate the potential of using semiconductor nanostructures to engineer
efficient, scalable, and broadband optical components in obtain light processing
through flat surfaces
Terahertz near-field microscopy investigation of plasmons in 2D nanomaterials
No full textTHz radiation covers a portion of the electromagnetic spectrum that is very hard to investigate. Visible and radio frequencies are well studied and relatively easy to generate. The energy of photons with frequencies in the visible spectrum is of the same order of magnitude of atomic transitions. Exploiting the process of stimulated emission it is possible to create a laser that emits photons in the visible spectrum. Radio waves can be generated by alternating electrical current. In the region between visible and radio waves a common radiation sources are of Quantum Cascade Lasers (QCL) sources that actually require cryogenic temperatures. This makes the investigation of THz frequencies very difficult. This is unfortunate, since THz radiation has the potential for many applications. The energy of vibrational and rotational transitions of many atoms and molecules falls in this spectral range. This allows the use of THz radiation to identify atoms and molecules. Another possible application is in airport security where a non intrusive method of identification of illegal substances is required, or in industry to monitor production.
Using radiation in THz range in microscopy appears unfeasible at the first glance. Diffraction limit imposes that an optical microscope employing THz radiation would be unable to have a resolution lower then 0.61 λ/n, with λ being the THz wavelength and n being the index of refraction. This means that details smaller then 100 µm cannot be easily unveiled. This limit holds for microscopes that use far field radiation. In this work we demonstrate a novel THz near field optical microscopy technique in which a QCL source is simultaneously used as source and detector in the self-mixing configuration. We used a scattering-type Scanning Near Field Microscope (SNOM) by Neaspec GmbH.
Self-mixing interferometry is a measurement technique that makes use of the coherence properties of a laser beam and of the high sensitivity of interferometric detection. In this technique the laser beam is reflected from an object back inside the laser. The reflected light and the generated light interferes inside the laser cavity, causing changes in the optical mode and the laser voltage. Those changes are monitored and recorded by lock-in amplification.
In this work we describe the optical setup in details, together with the alignment procedures such as the use of the pilot laser for the crude alignment and the use of the self mixing signal itself for the finer alignment.
As application of this novel instrument we probed 2D nanomaterials. In particular, we investigated black phosphorus, tin selenide (SnSe) and tin diselenide (SnSe2). In order to be able to change the carriers density inside those materials, influencing their response to the THz radiation, we fabricated several field effect transistor devices (FETs) for each material. The fabrication process was performed inside the facilities of Laboratorio NEST - National Enterprise for nanoScience and nanoTechnology. The fabrication procedures such as substrate preparation, mechanical exfoliation, SEM image acquisition, transistor design, electronic beam lithography, reactive ion etching, evaporation, lift-off, atomic layer deposition and bonding are described. The setup for electrical characterization of the produced FETs is presented.
The final scans acquired by the self-mixing SNOM setup are presented and discussed. For devices of each material the topography maps, the THz scans and the electrical characteristics are provided
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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