1,720,973 research outputs found
Anatectic melt trapped in garnet from migmatites of the Kerala Khondalite Belt, Southern India: evidence from crystallized and glassy melt inclusions.
No full textEffects of the mixing of charge transfer and molecular excitations on the resonance Raman properties of symmetric radical dimers
No full textCOUPLING OF ELECTRONS TO LOW-FREQUENCY PHONONS IN CATION-RADICAL SALTS OF TTF STUDIED BY RESONANCE RAMAN-SCATTERING
No full textCoupling of charge transfer transitions to low frequency phonons in quasi-one-dimensional radical ion salts: resonance Raman study of tetraethylammonium-DDQ
No full textCOUPLING OF ELECTRONS TO INTERMOLECULAR PHONONS IN MOLECULAR CHARGE-TRANSFER DIMERS - A RESONANCE RAMAN-STUDY
No full textWe report resonance Raman scattering RRS spectra and Raman excitation profiles REP of a system containing dimers of identical molecular radical ions measured with laser excitation in resonance with the charge transfer CT transition. A Peierls–Hubbard PH Hamiltonian has been used to model the investigated system and to calculate its optical and RRS properties. Results are reported for two polyoxometallate salts of tetrathiafulvalene TTF, namely TTF2W6O19) and TTF2 Mo6 O19) whose structures contain almost isolated TTF ) 2 dimers. The RRS spectra of TTF2W6O19), measured in resonance with the CT absorption band centered at 832 nm, show 1 three phonon modes located at 55, 90, and 116 cm modes have been associated to the out-of-phase combinations of the translational motions of the two molecules composing the dimer. Such modes are effective in modulating the intradimer transfer integral, thus providing an efficient mechanism for coupling with the electronic system and for enhancement of the scattering intensity at resonance with the CT transition. The REP for the three strongly coupled modes of TTF2W6O19) have been measured with laser excitation wavelengths ranging from 740 to 930 nm. Quantitative analysis of the REP data has been performed based on a perturbative solution of the PH model to second order in the electron-molecular-vibration EMV and electron-intermolecular-phonon EIP interactions. The CT absorption profile and the REP’s have been calculated using a time correlator technique and the model parameters have been optimized in order to fit the experimental REP data. Infrared vibronic absorptions of TTF2W6O19), originated by the EMV coupling, have been measured and independent information on the electronic parameters of the PH model have been derived. This has made the choice of the fitting parameters used for the REP calculations rather unambiguous and has allowed us to obtain, for the first time, reliable experimental estimates of the EIP coupling constants
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
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