1,720,989 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
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
At the extremes of spin dynamics: organic co-crystals and nv− diamond as materials for masers and microwave mode cooling
No full textThe suitability of the three charge transfer co-crystals anthracene with 1,2,4,5-tetracyanobenzene
(A:TCNB), phenazine with 1,2,4,5-tetracyanobenzene (PNZ:TCNB) and acridine with 1,2,4,5-
tetracyanobenzene (Acri:TCNB) as maser gain media was assessed. The ability for NV− centres
in diamond to act as a spin-cold material that can cool a microwave mode at 2872 MHz is also
presented. Through the construction of a homemade transient electron paramagnetic resonance
(trEPR) spectrometer, the triplet EPR signals of all four materials were measured and used to
find their resonant frequencies and solve their triplet spin dynamics. The co-crystals A:TCNB
and PNZ:TCNB were shown by simulation to feasibly support masing at transition frequencies
above 2 GHz, but experiments with A:TCNB could not yet produce masing signals. NV− diamond
on the other hand succeeded as a microwave mode cooler, able to cool the mode from
room temperature down to 188 K and hold that temperature for 10 milliseconds when measured
using a heterodyne receiver setup.Open Acces
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
Manipulating enhanced photoluminescence of upconversion nanoparticles by plasmonic nanostructures and broadband light absorption
Full text linkRare-earth upconversion nanoparticles, such as those composed of lanthanide-doped NaYF4,
can convert two or more low-energy photons at longer wavelength into one high-energy photon
at a shorter wavelength. Solar water splitting devices that incorporate them can therefore
harvest otherwise lost photons in the near-infrared region of the electromagnetic spectrum.
The conversion e ciencies of these nanoparticles have, however, been extremely poor to date,
eliminating any potential bene t (with respect to the photocurrent of water splitting devices
themselves) of being incorporated into photoelectrode devices. Towards overcoming this impasse,
the aim of this Ph.D project is to investigate the feasibility of a hybrid photoelectrode system
where upconverting nanoparticles are coupled to a plasmonic structure and conjugated with
dye molecules that absorb below bandgap photons. The synergistic enhancement e ect of
plasmonic and broadband absorption of dye molecules could signi cantly improve the conversion
e ciency of lanthanide-doped NaYF4. The dye molecules act as a sensitiser: they absorb
near-infrared light over a broad range and subsequently transfer the associated energy to the
their upconverting nanoparticles via F orster resonance energy transfer. On the other hand, the
plasmonic components enhance both the upconversion process and F orster resonance energy
transfer process, by increasing the incident electromagnetic eld intensity and the radiative
emission rate via surface plasmon resonance.
In this project, hexagonal phase NaYF4 co-doped with Yb3+ and Er3+ upconversion nanocrystals
(UCNPs) were synthesized. Plasmonic enhanced upconversion; dye-sensitised upconversion,
and nally plasmonic broadband dye-sensitised upconversion were investigated using Au nanodisk
(AuND) 2D arrays. The enhanced upconversion were observed with 26-fold and 19-fold
enhancements for green and red emission on AuND arrays, respectively. In parallel, single
infrared dye IR808 and multiple infrared dyes were conjugated to UCNPs, with 5.5-fold and
3.9-fold enhancements observed in green emission. Finally, plasmonic enhanced broadband
upconversion with 10-fold enhancement was recorded. For proof of concept, UCNPs and
three-dye-sensitised UCNPs coupled with AuND arrays were deposited on hematite-based photoelectrodes.
Photocurrent was clearly obtained from UCNPs coupled hematite on AuND arrays
when excited below the bandgap of hematite. The proof of concept established in this thesis
could not only nd applications in arti cial solar water splitting, but also has huge potential in
applications such as biological sensing, imaging and therapy based on upconversion nanoparticles.Open Acces
Kerr-induced optical mode splitting and Kerr-optomechanical interactions in microresonators
No full textThe Kerr effect is a third order nonlinear effect in optics that affects the refractive index with respect to the optical intensity of a light wave travelling through a nonlinear medium. Ultra-high-Q microresonators have the ability to induce significant third order nonlinearities, at low optical input powers. Power-dependent resonance shifts of more than 30 linewidths were measured, induced by the Kerr effect, for continuous-wave lasers in both co- and counter-propagating directions. The frequency shifts are different for lasers of different intensity, due to the nonequal contributions of self- and cross-phase modulation. This results to an effective splitting of the optical mode. A further effective splitting occurs from unequal Kerr contributions in the two counterpropagating circulating directions of the cavity, due to four-wave mixing only occurring in the co-propagating direction. Two otherwise identical counterpropagating light
fields would therefore undergo different resonance shifts. The induced nonreciprocity finds applications in optical switching, memories, and logic gates, while the splitting itself affects
optomechanical coupling to mechanical degrees of freedom. Controlling the pump laser’s power
and detuning determines how the amplitudes and phases of the mechanical oscillation behave,
measured through the generated Stokes and anti-Stokes sidebands. Better understanding of
the optically-induced mechanical motion benefits research done on phonon lasers, mechanically induced rf combs, and mechanical solitons, as well as applications in which the optical field mediates phonon transfer between different mechanical modes.Open Acces
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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