1,721,427 research outputs found
Evidence of unconventional low-frequency dynamics in the normal phase of Ba(Fe_{1−x}Rh_{x})_{2}As_{2} iron-based superconductors
No full textThis work presents 75As NMR spin-echo decay rate (1/T2) measurements in Ba(Fe1−xRhx )2As2 superconductors,
for 0.041 <x< 0.094. It is shown that 1/T2 increases upon cooling, in the normal phase, suggesting the
onset of an unconventional very low-frequency activated dynamic. The correlation times of the fluctuations and
their energy barriers are derived. The motion is favored at large Rh content, while it is hindered by the application
of a magnetic field perpendicular to the FeAs layers. The same dynamic is observed in the spin-lattice relaxation
rate, in a quantitatively consistent manner. These results are discussed in the light of nematic fluctuations involving
domain wall motion. The analogies with the behavior observed in the cuprates are also outlined
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Field-dependent Hall effect in single-crystal heavy-fermion YbAgGe below1K
Get PDFWe report the results of a low-temperature (T >= 50 mK) and high-field (H 0. At the base temperature, the functional form of the field-dependent Hall coefficient is field-direction-dependent and complex beyond existing simple models, thus reflecting the multicomponent Fermi surface of the material and its nontrivial modification at the quantum critical point.This article is published as Bud’ko, S. L., V. Zapf, E. Morosan, and P. C. Canfield. "Field-dependent Hall effect in single-crystal heavy-fermion YbAgGe below 1 K." Physical Review B 72, no. 17 (2005): 172413.
DOI: 10.1103/PhysRevB.72.172413.
Copyright 2005 American Physical Society.
Posted with permission
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
NMR investigation of vortex dynamics in the Ba(Fe0.93Rh0.07)2As2 superconductor
Get PDF75As NMR spin-lattice relaxation (1/T1) and spin-echo decay (1/T2) rate measurements were performed in
a single crystal of Ba(Fe0.93Rh0.07)2As2 superconductor. Below the superconducting transition temperature Tc,
when the magnetic field H is applied along the c axes, a peak in both relaxation rates is observed. Remarkably
that peak is suppressed for H ⊥ c. Those maxima in 1/T1 and 1/T2 have been ascribed to the flux lines lattice
motions and the corresponding correlation times and pinning energy barriers have been derived on the basis of
a heuristic model. Further information on the flux lines motion was derived from the narrowing of 75As NMR
linewidth below Tc and found to be consistent with that obtained from 1/T2 measurements. All the experimental
results are described in the framework of thermally activated vortices motions
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