1,720,965 research outputs found
The x-ray absorption spectrum of the <i>tert</i>-butyl radical:An experimental and computational investigation
No full textWe report the x-ray absorption spectrum (XAS) of the tert-butyl radical, C4H9. The radical was generated pyrolytically from azo-tert-butane, and the XAS of the pure radical was obtained by subtraction of spectra recorded at different temperatures. The bands in the XAS were assigned by ab initio calculations that are in very good agreement with the experimental data. The lowest energy signal in the XAS is assigned to the C1s electron transition from the central carbon atom to the singly occupied molecular orbital (SOMO), while higher transitions correspond to C1s excitations from terminal carbon atoms. Furthermore, we investigated the fragmentation of the radical following resonant C1s excitation by electron-ion-coincidence spectroscopy. Several fragmentation channels were identified. The C1s excitation of the terminal carbons is associated with a stronger fragmentation tendency compared to the lowest C1s excitation of the central carbon into the SOMO. For this core excited state, we still observe an intact parent ion, C4H9+, and a comparatively higher tendency to dissociate into CH3+ + C3H6+
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
Photoelektronen Spektroskopische Charakterisierung von Methylieren p-Block Radikalen
No full textThis work has provided a systematic and comparative investigation of lowvalent
main group radicals of the form E-CH3, spanning Groups 13, 15, and
16 of the periodic table. Through the combination of threshold photoelectron
spectroscopy with mass-selective detection and pyrolytic precursor fragmentation,
it was possible to isolate and characterize a wide range of transient
species, many of which had not previously been observed in the gas phase.
Notably, the ability to directly distinguish between σ- and π-bonding type
structures, as well as to detect small changes in geometry upon ionization,
highlights the power of ms-TPES for structural identification of reactive
intermediates. The observed similarities and differences within and across
groups offer insight not only into the underlying electronic structure of these
species, but also into the broader reactivity landscape of low-valent main
group chemistry.Diese Arbeit lieferte eine systematische und vergleichende Untersuchung niedervalenter Radikale der Hauptgruppenelemente der Form E-CH3, die sich über die Gruppen 13, 15 und 16 des Periodensystems erstrecken. Durch die Kombination von Threshold-Photoelektronenspektroskopie mit massenselektiver Detektion und pyrolytischer Fragmentierung geeigneter Vorläufer konnten zahlreiche kurzlebige Spezies isoliert und charakterisiert werden, von denen viele zuvor noch nie in der Gasphase beobachtet wurden. Besonders hervorzuheben ist die Fähigkeit der ms-TPES, σ- und π-gebundene Strukturen direkt zu unterscheiden sowie selbst kleinste Geometrieänderungen bei der Ionisierung aufzudecken. Dies unterstreicht das Potenzial dieser Methode zur strukturellen Identifizierung reaktiver Intermediate. Die innerhalb und zwischen den Gruppen beobachteten Gemeinsamkeiten und Unterschiede liefern nicht nur Einblicke in die zugrunde liegende elektronische Struktur dieser Spezies, sondern erweitern auch das Verständnis der Reaktivitätslandschaft niedervalenter Hauptgruppenelemente
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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