1,721,033 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
rotational spectrum of complex organic molecules: 2(N)-methylamminoethanol
No full textThe detection of molecules in space, is based on their spectroscopic features and high resolution spectral data is needed to allow an unambiguous identification of them.
Many of the molecules detected in space are complex organic molecules containing chains of carbon atoms and which therefore show a high degree of molecular flexibility. The high number of low energy conformations and the presence of large amplitude motions on shallow potential energy surfaces are peculiar to this kind of systems. The presence of a high number of stable conformers - often interconverting through small energy barriers - usually gives rise to very complex spectra, which represent a challenge for spectroscopic and computational methods.
We report the rotational study of methylaminoethanol (MAE) performed by Free Jet Absorption Microwave Spectrocopy (FJAMW). For this species it has proved essential to compute the complete potential energy surfaces related to the low amplitude modes. This has been calculated at the B3LYP/6-311++G** level of theory while the stable geometries have been characterized MP2/6-311++G**. The interest in the conformational properties of MAE is twofold: in the first place, aminoethanol and thus also MAE can be considered precursors of aminoacids in the interstellar medium \footnote{ S.~Charnley, in Proceedings of the workshop: The bridge between the Big Bang and Biology, CNR, Italy 1999.} and secondly, the MAE side chain is present in important biological molecules such as adrenaline. The conformational preferences of MAE are dominated by the intramolecular hydrogen bond between the OH and NH2 groups and its flexibility and asymmetry generate a very high number of conformers. 24 stable conformations have been predicted and two conformers were observed by FJAMW spectroscopy with our 60-72 GHz spectrometer. With respect to a previous study\footnote{ R.~E.~Penn and L.~W.~Buxton \textit{J.~ Mol.~Spectrosc.} \underline{\textbf{56}} 229 1975.} we have extended the observed frequency range, partly reassigned the rotational spectrum of one of the conformers and determined the nuclear quadrupole constants. The search for higher energy conformers has also been undertaken
The rotational study of a flexible molecule: 2(N)-methylaminoethanol A challenge for rotational spectrosopy
No full textFlexible molecules show a complex conformational space, generally shaped by non bonding interactions occurring within the molecule or with the surroundings and represent therefore a challenge for computational methods and rotational spectroscopy because of the presence of high number of stable conformations and large amplitude motions.
We report the rotational study of 2(N)-methylaminoethanol (MAE) performed by Free Jet Absorption Microwave Spectrocopy (FJAMW). This choice of study the conformational properties of MAE is mainly due to the fact that aminoethanol and thus also MAE can be considered a precursors of aminoacids in the interstellar medium (1) and secondly, the methyl-aminoethanol side chain is present in important biological molecules such as adrenaline, so we can consider it like a model for the chain’s interactions. The high vacuum conditions that we obtained with this technique reproduce those of the interstellar medium and this makes these kind of experiments very useful to guide astrophysical studies that aim at finding life precursors. Infact, because of the unique spectral signatures provided by rotational spectroscopy, much of the chemical inventory of the interstellar medium has been detected using radio telescopes operating in the centimeter and millimeter wavelenghts regions (2). Moreover the unusual chemical environments in this spatial region can produce novel chemical reaction processes, that involve less stable conformational species.
The conformational preferences of MAE are dominated by the intramolecular hydrogen bond between the OH and NH2 groups. The high flexibility of this molecule involves a complex energy potential surface with a large number of possible stable conformations. Infact for MAE 24 stable conformations have been predicted and two conformers were observed by FJAMW spectroscopy with our 60-72 GHz spectrometer. With respect to a previous study (3) we have extended the frequency range to 72 GHz and partly reassigned the rotational spectrum of one of the conformers.
(1) S. Charnley , in Proceedings of the workshop: The bridge between the Big Bang and Biology, CNR, Italy 1999.
(2) J. L. Neill et all., J. Phys. Chem. A, 2011, 115 (24), pp 6472–6480.
(3) R. E. Penn and L.W. Buxton, J. Mol. Spectrosc. 56, 229, 1975
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
Rotational spectrum, dynamics, and bond energy of the floppy dimethylether⋯neon van der Waals complex
No full textDispelling 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
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