1,721,013 research outputs found
Quantum size effects and temperature dependence of low-energy electronic excitations in thin Bi crystals
No full textThe quantum size effect (QSE) and temperature dependence of the low-energy electronic properties of thin bismuth crystals are studied by means of the high-resolution electron-energy-loss spectroscopy (HREELS) technique. Electronic interband transitions, taking place at the points L and T of the bismuth Brillouin zone (BZ), are distinctly brought into evidence at 47 and ∼200 meV, and the corresponding complex dielectric function in this energy region is determined. This provides direct experimental determination of the electronic transition from the Fermi level (EF) to the point T6+. The quantum size effect in thin Bi crystals is studied following the evolution of these electronic excitations as a function of the crystal thickness (110-2500). A downshift (upshift) of the transition at the point (T) of the BZ is measured by HREELS, and shown to be related to the Fermi-level modification as a function of thickness. This experimental finding is consistent with the theoretical predictions for the QSE-induced Fermi-level shift. In addition, the same experiment is performed as a function of temperature for crystals 750 thick, for which QSE's are not expected, and for crystals 200 thick which exhibit QSE's. A redshift by ∼12 meV of the lower-lying electronic excitation is measured on decreasing the temperature from 298 to 155 K. The energy shift is mainly due to the temperature dependence of the gap energy (Eg) in L. However, the temperature evolution of the occupancy of the filled and empty levels involved in the transition (through the width of the Fermi-Dirac distribution function around EF) cannot be neglected in fully determining the observed temperature dependence. These two causes are still determinant when the crystal is in a QSE regime
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
Polarization Effects of Transversal and Longitudinal Optical Phonons in Bundles of Multiwall Carbon Nanotubes
No full textWe report on the polarization analysis of the Raman spectrum of highly vertically aligned multiwall carbon nanotubes (MWCNTs). A simple model considering the average angle distribution across the MWCNT axes accounts for the observed angular dependent Raman mode intensity. The model fully fits the experimental data, allowing to derive an average waving angle of similar to 37 degrees around the MWGNT axes and explaining the apparent discrepancy of previous experiments reported in the literature. Furthermore, we can distinguish two components in the Raman G-band, associated to the longitudinal and transversal optical modes. Their intensity dependence as a function of polarization clearly suggests the metallic nature of these MWCNTs, experimentally verified by the valence band photoemission analysis. The present study provides a simple, effective spectroscopic method to determine physicochemical and specific morphological characteristics of carbon nanotubes
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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