1,720,972 research outputs found
Weak ferromagnetism in BiFeO3 doped with titanium
No full textThe Bi(1-x)A(x)Fe(1-x)Ti(x)O(3) (A-Ca, Sr, Pb, Ba) and BiFe1-xTixO3+delta systems have been studied using X-ray, neutron powder diffraction and magnetization measurements in a magnetic field up to 14 T. It was found that all Bi(1-x)A(x)Fe(1-x)Ti(x)O(3) solid solutions are rhombohedral up to x = 0.3. In the case of BiFe1-xTixO3+delta the rhombohedral distortion preserved up to x = 0.11. A homogeneous weakly ferromagnetic state was found for Bi1-xCaxFe1-xTixO3 (0.15 0.1 seem to be collinear antiferromagnets. (C) 2009 Elsevier B.V. All rights reserved.Belarussian Fund for Fundamental Research [T09-090
Magnetic structure of the manganites heavily doped by Fe and Cr ions
No full textPowder neutron diffraction and magnetic studies have been performed for NdMn0.5Fe0.5O3 and NdMn0.5Cr0.5O3 manganites. In NdMn0.5Cr0.5O3, magnetic structure has been revealed consisting of ferromagnetic and G-type antiferromagnetic components as result of a 3d-ions magnetic moments ordering. Magnetic moments of Nd-ions are parallel to the ferromagnetic component. In NdMn0.5Fe0.5O3 only the anti ferromagnetic G-type structure has been found whereas Nd-sublattice was not ordered. In the both compounds, magnetic moments of 3d-ions are significantly less than one can expect, what is interpreted in terms of intrinsic chemical inhomogeneity. Magnetic phase diagrams have been constructed for the Nd(Mn1-xMx)O-3 (M = Fe, Cr) systems, interpreted assuming superexchange interactions Mn3+-O-Cr3+ to be positive, Mn3+-O-Fe3+ negative and taking into account a disordered arrangement of Mn and Cr ions in the crystal structure sublattice as well as interplay between Jahn-Teller effect and superexchange interactions. (c) 2006 Elsevier B.V. All rights reserved
Magnetic interaction in Mg, Ti, Nb doped manganites
No full textAn effect of Mn substitution with Me=Mg2+, Ti4+, Nb5+ in manganites has been
investigated by preparing La0.7Sr0.3(MnMex)O3 and LaSrx(MnNb)O3 series. It
was established that substitution of manganese with magnesium up to x=0.16 leads to a
collapse of a long-range ferromagnetic order whereas La0.7Sr0.3(MnNb)O3 is
ferromagnet with TC=123 K and exhibits a large magnetoresistance below Curie point
despite an absence of four-valent manganese. Hypothetical magnetic phase diagrams are
constructed for La0.7Sr0.3(MnMex)O3 and LaSrx(MnNb)O3. Our results show
that Mn3+-O-Mn3+ exchange interaction is ferromagnetic in the orbitally disordered
manganites as well as an increase of Mn4+ content above 50% from a total amount of
manganese ions leads to formation of a spin glass state due to a competition between
antiferromagnetic Mn4+-O-Mn4+ and ferromagnetic Mn3+-O-Mn4+(Mn3+) superexchange
interactions
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
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
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