1,721,032 research outputs found
Beyond NICS: estimation of the magnetotropicity of inorganic unsaturated planar rings
No full textA simple classical model of magnetic-field induced electron flow is used to evaluate the ring current strength for a few inorganic monocyclic compounds. It is shown that, for these neutral and charged systems, sustaining delocalized electron
currents in the presence of a magnetic field Bext orthogonal to the sh plane, the out-of-plane
component of the nuclear magnetic shielding along the central axis is connected to the out-of-plane
magnetizability by a simple equation, involving the radius of an average loop of current. A novel
estimate of this effective radius is provided. Reliable ring current susceptibilities (that is, current
strengths) can be evaluated by a simple relationship, using the out-of-plane components of nuclear
shielding and magnetizability tensors. The accuracy of the current susceptibilities calculated by the
classical model is established by comparison with corresponding ab initio estimates obtained by
integrating the quantum mechanical current-density vector field. The out-of-plane components of
nuclear shielding and magnetizability are both strongly biased by the molecular geometry. Their
combined use to estimate the ring current susceptibility offers a quantifier of magnetotropicity
more reliable than (i) the out-of-plane component of magnetizability, (ii) the out-of-plane
component of the magnetic shielding at the center of mass.
The inadequacy of these commonly adopted magnetotropicity measures is demonstrated by
comparing a set of related molecules, C6H6 and Si6H6, N6 and P6
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
Non trivial chiroptical responses: experimental and theoretical investigations
No full textIn the past few years, our two groups of research have been collaborating on a number of projects
dealing with the assignment of the absolute configuration (AC) of complex chiral molecules of phar-
macological interest in the disordered phase. [1] These studies have been mainly carried out by means of
electronic circular dichroism (ECD) spectroscopy and quantum mechanical (QM) calculations at the den-
sity functional theory (DFT) level of approximation. Particular attention has been payed to non-trivial
chiroptical responses due to conformational flexibility and solvation.
Beside these shared activities, some more specific research fields have been investigated too. In par-
ticular, the Bologna group has performed studies concerning the hyphenation of enantioselective HPLC
methods with detection systems based on ECD [2] and the characterization of biomolecular recognition
phenomena between drugs and target or carrier macromolecules. [3] The Salerno group has developed
some skills in vibrational circular dichroism (VCD) [4] and chiral NMR [5] spectroscopies, thanks to the
availability of a VCD spectrometer and previous studies concerning the non-linear response of molecules
exposed to radiation.
[1] (a) C. Bertucci, M. Pistolozzi, D. Tedesco, R. Zanasi, R. Ruzziconi, A. M. Di Pietra, J. Chromatogr. A 2012, 1232,
128–133; (b) D. Tedesco, R. Zanasi, A. Guerrini, C. Bertucci, Chirality 2012, 24, 741–750; (c) F. Dong, J. Li, B.
Chankvetadze, Y. Cheng, J. Xu, X. Liu, Y. Li, X. Chen, C. Bertucci, D. Tedesco, R. Zanasi, Y. Zheng, Environ. Sci.
Technol. 2013, 47, 3386–3394; (d) W. J. Andrioli, R. Conti, M. J. Araújo, R. Zanasi, B. C. Cavalcanti, V. Manfrim,
J. S. Toledo, D. Tedesco, M. O. de Moraes, C. Pessoa, A. K. Cruz, C. Bertucci, J. Sabino, D. N. P. Nanayakkara,
M. T. Pupo, J. K. Bastos, J. Nat. Prod. 2014, 77, 70–78; (e) D. Tedesco, R. Zanasi, I. W. Wainer, C. Bertucci, J.
Pharm. Biomed. Anal. 2014, 91, 92–96.
[2] (a) C. Bertucci, D. Tedesco, J. Chromatogr. A 2012, 1269, 69–81; (b) D. Tedesco, A. M. Di Pietra, F. Rossi, M.
Garagnani, E. Del Borrello, C. Bertucci, V. Andrisano, J. Pharm. Biomed. Anal. 2013, 81-82, 76–79.
[3] (a) G. A. Ascoli, E. Domenici, C. Bertucci, Chirality 2006, 18, 667–679; (b) M. Pistolozzi, C. Bertucci, Chirality
2008, 20, 552–558;
[4] (a) A. Lattanzi, A. Russo, P. Rizzo, G. Monaco, R. Zanasi, Chirality 2010, 22, E130–E135; (b) A. Massa, P. Rizzo,
G. Monaco, R. Zanasi, Tetrahed. Lett. 2013, 54, 6242–6246.
[5] (a) S. Pelloni, P. Lazzeretti, R. Zanasi, J. Chem. Theory Comput. 2007, 3, 1691–1698; (b) G. Monaco, R. Zanasi,
Chirality 2011, 23, 752–755
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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