1,720,963 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
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
Dissipative and fluctuating effects in Ba(Fe1-x Rhx)2As2 iron-based superconductors
No full textThis thesis addresses dissipative and fluctuating mechanisms, taking place both in the superconducting, and in the normal phase of the Rh-doped family of 122 iron-based superconductors. These novel materials have been holding the stage of superconductivity, and renewing the interest in high temperature superconductors, for the last six years. Iron-pnictides are extremely type-II superconductors, with a Ginzurg-Landau parameter k-100, and extremely high upper critical fields, that can reach up to 100 T! Moreover, the lower critical field Hc1 is of the order of few mT, so there is a very broad range of magnetic fields in which the behavior of the vortex matter can vary significantly.
Nuclear Magnetic Resonance (NMR) is the more widely employed experimental tool in this thesis, given its microscopic nature, and the sensitivity to kHz-MHz fluctuations, that well match the vortices dynamic timescale. However, not many NMR studies concerning the dynamic in the iron-pnictides of the vortex lattice have been carried out, so far. One possible reason may be that the vortex dynamic is strongly related to technological applications, whereas NMR usually probes the equilibrium state.
Even though from a technological point of view this regime is not very appealing, it can anyhow help to grasp some information about the nature of the solid vortex phase.
The thesis is organized as follows: Part I includes the first two chapters. The first chapter presents an overview of structural, electronic and magnetic properties of the materials. A whole section reports the main NMR results obtained on 122 iron-pnictides, up to now. The second chapter presents the basic aspects of NMR, which are needed to understand the experimental results. Part II includes chapters 3-7. The third chapter discusses the onset of unconventional fluctuative phenomena of the order parameter, taking place above Tc. Such issues were studied by SQUID magnetometry. Chapter 4 debates an NMR study of the anomalous enhancement of the spin-spin decay rate, in the normal state.
The phenomenology of these systems becomes even richer, below the transition temperature, where the vortex lattice dynamic, in equilibrium condition (Chapter 5), and out-of-equilibrium (Chapter 6) can be investigated by NMR. Finally, chapter 7 deals with novel methodologies to study the vortex lattice melting transition. Part III is devoted to the appendices, which describe both the experimental equipment, and some theoretical background
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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