1,720,969 research outputs found
Frequency dependence of coercive properties
No full textSignificant frequency dependence of domain wall coercive field, due to the widening of the hysteresis loops, was observed based on AC hysteresis curve measurements in epitaxial magnetic garnet films. Domain wall oscillation measurements did not reveal any frequency dependence. The different results of the two measurement methods were analyzed, and the observed frequency dependence was attributed to the inertia of the moving domain walls. It was shown that the real value of the domain wall pinning field cannot be determined by AC hysteresis measurements, even in non-conducting materials
Dipolar-random-field Ising model: An application to garnet films
No full textThe dipolar-random-field Ising model (DRFIM) recently introduced [A. Magni, Phys. Rev. B 59, 985 (1999)] displays a behavior that can be connected to the magnetization of bidimensional magnetic media. Epitaxial magnetic garnet films seem to be the ideal test material for such a model. In this work the results of the measurements performed on garnet samples are presented, as well as the comparisons with simulation results obtained by the DRFIM. The results prove that a variety of hysteresis loops are well described by the DRFIM. This capability does not derive from the fine tuning of a great number of parameters, but by the interplay of exchange and dipolar interactions
On the correlation between the widths of minor and major magnetic hysteresis loops
No full textThe widths of the minor and major hysteresis loops were investigated in epitaxially grown uniaxial magnetic garnet
films. It was found that minor loops can be wider than the major loop. This relationship can be turned into the opposite
in the same sample by its proper processing. The phenomenon was interpreted, showing the difference in the character of
the technical coercive force and of domain wall pinning field
Anomalous behaviour of minor magnetic hysteresis loops in garnet films
No full textThe widths of the minor hysteresis loops were investigated in epitaxially grown uniaxial magnetic garnet films as a function of the maximal magnetic field at the end of the loops. An anomalous behaviour of the minor loops was observed in several samples: the width of a minor loop decreased with increasing maximal field. The phenomenon was interpreted on the basis of domain wall nucleation. Different coercive fields (the domain wall coercive field, H-cw, and the technical coercive field, H-ct) and their relation were also discussed
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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