1,721,156 research outputs found
The influence of molecular-organization on charge transport in electrochemically prepared polypyrrole films
No full textLetter to the editor. Electrical conductivity data is presented for two types of polypyrrole film prepared using toluene sulphonate and sulphate as the counter-ions or dopant. The films based on polypyrrole and toluene sulphonate exhibit an ordered molecular organisation in which the planes of the aromatic units lie preferentially parallel to the film surface. For such films the conductivity versus temperature data fit to a 2D variable range hopping model. In contrast, films using SO42- as the dopant show an isotropic highly disordered molecular organisation and a temperature dependence of the electrical conductivity which fits a 3D variable range hopping model. Although such models present a rather simple picture of conductivity in these complex molecular composites, they do demonstrate the strong and direct influence of the molecular organisation on their electrical transport properties
Non-Fermi-liquid behavior of electron-spin fluctuations in an elemental paramagnet
No full textWe report for the first time, the observation of non-Fermi-liquid scaling behavior in an elemental paramagnetic metal. Both the dynamical susceptibility and the resistivity of ?-Mn are shown to display non-Fermi-liquid scaling over a relatively large temperature range at ambient pressure. The temperature dependence of the resistivity in ?-Mn is consistent with the existence of an antiferromagnetic zero-temperature phase transition or “quantum critical point.” Since there is no site disorder in this pure element, we show that non-Fermi-liquid behavior observed in ?-Mn is not a consequence of summing over different local atomic environments, but a much more fundamental phenomenon.<br/
Target optimisation studies for the European Spallation Source
Full text linkThe European Spallation Source (ESS) is one of Europe’s
biggest and most prestigious science projects. ESS
will be the world’s most powerful next generation neutron
spallation source for research with neutrons, providing a
unique tool for studies of the atomic structure and dynamics
of matter. In this paper we use GEANT4 simulations
to investigate the effects of spallation target material and
incident proton energy on the total neutron yield integrated
over the neutron energy and emission angle
GEANT4 Validation Studies at the ISIS Muon Facility
No full textGEANT4 provides an extensive set of alternative
hadronic models. Simulations of the ISIS muon production
using three such models applicable in the energy range
of interest are presented in this paper and compared with
the experimental data
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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