1,720,963 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
Ultrafast Spectroscopic Studies on Chemically and Biologically Relevant Aqueous/Non-Aqueous Environments
Full text linkFirst principles study of the structural, electronic, elastic, mechanical, thermal, and vibrational properties in pyrochlores and temperature-dependent phonon properties in pyrochlores and SrTiO3 perovskite
Full text linkIn this thesis, first-principles density functional theory (DFT) calculations are used to study the structural, electronic, elastic, mechanical, and thermal properties in a series of pyrochlore materials. The vibrational properties in these materials are also studied using density functional perturbation theory. Furthermore, and most importantly, a combination of DFT and many-body Green’s function approach is employed to study the temperature-dependence of the vibrational properties arising from anharmonic interactions in some of the pyrochlore compounds and in tetragonal SrTiO3 perovskite.
Chapters 1 and 2 of the thesis contain introductory material. Chapter 1 provides a brief introduction to the properties of pyrochlores and perovskites and motivates the work undertaken in this thesis. A brief description of the theoretical background for the calculations in the thesis – DFT, Density functional perturbation theory, lattice dynamics, and elasticity theory – are given in Chapter 2.
The structural, electronic, and vibrational properties of a series of rare-earth pyrochlores, RE2B2O7 (RE = Sm, Gd, Tb, Dy, Ho, Er, Yb, Lu and B = Ti, Zr, Hf) are explored in Chapter 3, using both LDA and GGA frameworks. A comparative analysis of how these properties depend on the rare-earth and transition metal cation radii is presented. Interesting findings include the presence of anomalous dynamical charges and structural instabilities which manifest as imaginary phonon frequencies. A small distortion of the atomic positions in the unit cell stabilizes the structure in the sense that the frequencies for all the modes become real. A comparative and comprehensive analysis of Raman and infrared active modes is also given.
In Chapter 4, a similar comparative study of the elastic, mechanical, and thermal properties of the same series of rare-earth pyrochlores as in the previous chapter is presented. Furthermore, results for the bulk modulus, elastic constants, shear and Young’s moduli to study the hardness of the materials, Poisson’s ratio to characterize their ionicity, Pugh’s ratio to understand their ductile and brittle nature, sound velocities, Debye temperature, and the minimum thermal conductivity are also discussed.
Chapter 5 contains results from high-pressure studies of the structural, elastic, and the vibrational properties of Dy2Ti2O7. A brief discussion of the isostructural phase transition observed around 9 GPa pressure in this compound is provided. Chapter 6 presents a comparative discussion of the structural, electronic, vibrational, elastic, mechanical, and thermal properties in the Y2B2O7 (B = Ti, Zr, Hf) pyrochlores.
Chapters 7-10, all devoted to studies of the temperature dependence of vibrational properties arising from phonon anharmonic effects in several pyrochlores as well as in tetragonal SrTiO3 using DFT and many-body Green’s function approach, present the most sophisticated calculations of this thesis. Chapter 7 contains studies which use an approximate form for the third-order interatomic force constant matrix elements (IFC3MEs) using one overall fitting parameter for all the modes to get a qualitative understanding of temperature-dependent phonon behaviour in Y2Ti2O7 pyrochlore. In Chapter 8, the temperature-dependent phonon properties in Y2B2O7 (B = Ti, Zr) pyrochlores are re-examined using the same DFT plus Green’s function approach, but this time calculating the IFC3MEs ab initio, using the “2n+1” theorem, implemented within density functional linear response theory. An interesting finding in both sets of calculations is the anomalous behaviour (of softening with decreasing temperature) of two high frequency phonon modes in case of Y2Ti2O7, whereas, no anomaly is found in case of Y2Zr2O7. In Chapter 9, the temperature dependence of phonon properties in RE2Ti2O7 (RE = Dy, Lu) pyrochlores is investigated using the same procedure as in Chapter 7. It is found that the third-order anharmonic shift in frequency for some of the phonon modes in these systems shows an anomalous behaviour, which is likely to be a signature of an anomalous temperature dependence of phonons in these materials that one will find if one calculates the IFC3MEs exactly.
Chapter 10 contains an exploration of the temperature-dependent phonons in tetragonal SrTiO3 perovskite using the methods of Chapter 8, but in this case no anomalous behaviour is found. The vibrational properties in the high temperature cubic phase of SrTiO3 are also studied, and strong structural instabilities as indicated by the imaginary frequencies for several of the optical modes are found.
Finally, Chapter 11 summarizes all the work presented in the thesis, together with some concluding comments and future outlook. The appendices present some technical details related to the thesis content
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
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