1,721,016 research outputs found
Chirality-induced switch in hydrogen-bond topology: Tetrameric methyl lactate clusters in the gas phase
No full textIsoelectronic Arduengo-type carbene analogues with the Group IIIa elements boron, aluminum, gallium, and indium
No full textSundermann A, Reiher M, Schoeller W. Isoelectronic Arduengo-type carbene analogues with the Group IIIa elements boron, aluminum, gallium, and indium. EUROPEAN JOURNAL OF INORGANIC CHEMISTRY. 1998;(3):305-310.While Arduengo-type carbenes are now well established for the Group IVa elements carbon, silicon and germanium, they are experimentally unknown for the isoelectronic anions with the Group IIIa elements boron, aluminum, gallium, and indium. In the present quantum chemical investigations, the bonding features of this class of compounds are explored. As a result, they are predicted to be stable species with sizeable singlet-triplet energy separations and electron affinities. Hence, they may be considered as valid targets for experimental investigations. An analysis of the electron density distribution in the case of boron and aluminum reveals a strongly polar B-N bond for the former, and a half Al-N bond with positive charge at the aluminum, emphasizing the donor-acceptor formulation for the latter
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Nuclear Quadrupole Moment of 119Sn
No full textSecond-order scalar-relativistic Douglas-Kroll-Hess density functional calculations of the electric field gradient, including an analytic correction of the picture change error, were performed for 34 tin compounds of which molecular structures and 119Sn Mössbauer spectroscopy parameters are experimentally known. The components of the diagonalized electric field gradient tensor, Vxx, Vyy, Vzz, were used to determine the quantity V, which is proportional to the nuclear quadrupole splitting parameter ΔE. The slope of the linear correlation plot of the experimentally determined ΔE parameter versus the corresponding calculated V data allowed us to obtain an absolute value of the nuclear quadrupole moment Q of 119Sn equal to Q = 13.2 ±0.1 fm2. This is about 11% larger than the picture-change-error-affected value and in good agreement with previous estimates of the picture change error in compounds of similar atomic charge. Moreover, despite the variety of the tin compounds considered in this study, the new result is in excellent agreement with the previously determined most accurate value of Q for 119Sn of Q = 12.8 ±0.7 fm2, but with a noticeably narrower error bar. The reliability of the calibration method in the calculation of the ΔE parameter of tin compounds is within a margin of ±0,3 mm s-1 when compared to experimental data and does not depend on the inclusion of the picture change correction in the density functional calculations but is essentially determined by the use of an atomic natural orbital relativistic core-correlated basis set for the description of the core electron density. The results obtained suggest that the present picture-change-corrected Douglas-Kroll-Hess approach provides reliable electric field gradients in the case of closed-shell metal compounds involving elements up to the fifth row of the periodic table for which spin-orbit coupling is negligible
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