1,721,021 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
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
The Suzuki-Heck polymerisation as a tool for the straightforward obtainment of poly(fluorenylene-vinylene) sensitisers for DSSCs
No full textThis article describes the synthesis and properties
of the first poly(arylene-vinylene)-based sensitizers for application
in dye-sensitized solar cells (DSSC). The polymers were
prepared by the Suzuki–Heck copolymerization of potassium
vinyltrifluoroborate (PVTB) with a mixture of dibromoaryl
comonomers designed to obtain macromolecules able to bind
onto the photoelectrode by means of carboxyphenylene units.
The copolymerization reactions were carried out in the presence
of an excess of PVTB to lower the molecular weights of
the polymers, which were obtained as soluble materials. The
polymers poly[(9,9-didodecyl-2,7-fluorenylene)-vinylene-co-(carboxy-
2,5-phenylene)-vinylene] (P1), poly[(9,9-didodecyl-2,7-fluorenylene)-
vinylene-co-(carboxy-2,5-phenylene)-vinylene-co-(4,7-
benzothiadiazolylene)-vinylene] (P2), and poly[(9,9-didodecyl-
2,7-fluorenylene)-vinylene-co-(carboxy-2,5-phenylene)-vinyleneco-
2,5-thienylene-vinylene] (P3) were used in DSSC devices,
obtaining conversion efficiencies up to 0.88% (P3)
Random terpolymers for electroluminescent devices: synthesis and characterization of new cyano–containing poly(fluorenylene–vinylene)s
No full textThe synthesis of new random poly(2,7-fluorenylene-vinylene)s was
achieved by a Suzuki–Heck cascade polymerization reaction. The poly(fluorenylenevinylene)
base structure was modified by the regio-random incorporation of 1-cyano-
2,5-phenylene as electron withdrawing unit (CN-PFV1) and its properties were compared
with terpolymers also embodying 1,4-dioctyloxy-2,5-phenylene (CN-PFV2) or
3,6-N-octylcarbazole (CN-PFV3) as electron-donating moieties. Thermal analysis
revealed a high thermal stability (Td [ 389 8C) and the absence of glass transitions
for all polymers. Cyclic voltammetry indicated a high electron affinity of the materials
(2.96–3.21 eV) attributed to the presence of the cyano-containing comonomer. In
dilute solutions, the copolymers showed a broad green fluorescence with quantum
yields ranging from 0.42 to 0.79, while in the solid state, a relatively narrow emission
centered at 560 nm, governed by the low-energy segments within the p-conjugated
backbone, was observed. The electroluminescence properties of the materials
were tested in OLED devices of ITO/PEDOT-PSS/CN-PFV1-3/Ca/Al or ITO/PEDOTPSS/
CN-PFV1-3/Alq3/Ca/Al configurations, showing a bright green-yellow emission
that, in the case of CN-PFV2, reached 1403 cd/m2 with efficiencies as high as 0.13
cd/A
Influencing the spectral stability and the electroluminescence behavior of new blue-emitting bifluorene-based materials by the 7,7′-functionalization of the core
No full textThis study concerns the preparation of novel monodispersed organic materials based on a tetrahexyl-bifluorene
core linked to end-groups by double or triple bonds. The molecules were designed aiming at tuning their
HOMO-LUMO levels without remarkably changing their optical properties. The syntheses were carried out
through a convergent-divergent approach by reaction of a 7,7¢-diiodobifluorene building block with 2-fluoren-
7-yl-ethynyl (BF1), 2-carbazol-3-yl-ethynyl (BF2), 2-fluoren-7-yl-ethenyl (BF3), and 2-carbazol-3-yl-ethenyl
(BF4) moieties. The analysis of the optical properties evidenced for BF1-4 an efficient blue emission in
solution. Their emission profile is preserved also in the solid state, except for that of BF4, the PL spectrum
of which showed the appearance of a green band deriving from aerobic degradation. The HOMO value of
-5.00 eV, measured for BF4 by cyclic voltammetry, suggested a correlation of the spectral instability with
its low ionization potential. This hypothesis was confirmed by the photoluminescence behavior of BF1-3
upon UV photoirradiation showing a correlation between spectral stability and ionization potential. OLED
devices of ITO/PEDOT-PSS/BF1-4/Ca/Al configuration exhibited a blue electroluminescence. Fair
performances were obtained for the carbazole-containing BF2 (1000 cd/m2 with a current efficiency of 0.039
cd/A at 10 V) and BF4 (1431 cd/m2 and 0.027 cd/A at 14 V) presumably due to a more balanced transport
of charge carriers in the active layer. The results obtained in devices embodying 7.5 nm of a hole-blocking
layer (BCP) between the calcium cathode and the emitting material showed a remarkable enhancement of
current efficiencies for all devices and confirmed a more balanced transport of charge carriers in the carbazolecontaining
molecules. The figures of merit obtained for the carbazole-containing BF2 (1088 cd/m2 and 0.070
cd/A at 10 V) represent one of the best results for blue-emitting materials embodying ethynyl groups
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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