1,720,997 research outputs found
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
Synthesis of Thin Film Mn3Sn and the Magnetic Behaviour of Thin Film LiFe5O8
Get PDFThis thesis presents an investigation into the synthesis of Mn3Sn and the magnetic
characterization of LiFe5O8 thin films, offering valuable insights into their
structural and magnetic properties.
Mn3Sn, a noncollinear antiferromagnet, crystallizes in a hexagonal Ni3Sn-type
structure with a Kagome lattice of Mn atoms. Its unique triangular spin texture
andWeyl semimetal status at room temperature give rise to intriguing magnetic and
electronic phenomena, including anisotropic magnetoresistance, anomalous Hall and
Nernst effects, and robust topological properties. This study highlights the significance
of phase purity in Mn3Sn synthesis and emphasizes the need for optimized
substrates and annealing conditions to achieve high-quality thin films suitable for
spintronic devices.
LiFe5O8, an inverse spinel material, exhibits ferrimagnetic order with high Curie
temperature and tunable magnetic properties. The structural versatility of LiFe5O8
allows for element substitution at cation sites, influencing its magnetic saturation,
coercivity, and dielectric behaviour. This work demonstrates the impact of film
thickness, substrate choice, and microstructural features on the magnetic properties
of LiFe5O8 thin films, underscoring their potential for high-frequency and low-power
spintronic applications.
The research employs advanced characterisation techniques, including X-ray
diffraction, magneto-optical Kerr effect, and first-order reversal curve analysis, to
unravel the magnetic behaviour of these materials. The findings contribute to the
growing field of magnetic materials, providing a foundation for future studies to
optimise synthesis processes, explore novel substrate interfaces, and integrate these
materials into functional spintronic devices. This thesis not only advances the understanding
of Mn3Sn and LiFe5O8 but also paves the way for their practical application
in next-generation memory storage, sensors, and high-frequency electronics
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
Structurally and magnetically complex materials: a magneto-caloric, a multiferroic skyrmion host and a ferrimagnetic semiconductor
Get PDFThe study of structural subtleties and complications in novel materials is often neglected and instead their physical functionality is investigated directly. When this is done however, details in the crystal structure can be missed which have significant consequences for the physical properties of the material. This thesis aims to prove this with the use of investigations of three separate inorganic systems which have very different atomic and magnetic structure, and therefore functionality, from each other. These investigations include the synthesis of polycrystalline and single crystal samples, followed by characterisation with the use of diffraction, magnetisation
and transport experiments, which are all introduced in Chapter 2. The most important concepts needed in the analysis of the collected data are explained in Chapter 3.
Chapter 4 re-examines the structure of incommensurate composite ferrimagnetic semiconductor Ba1–pCr2Se4–p, finding that a single crystal sample has a modulation vector of q = (0,0,0.24144) partly characterised by crenel occupational modulations, creating Se2− dimers. It also has large disorder in its sixfold channel which is modulated in its basal plane with q ≈ (1/3,1/3,0), although chemical composition is found to vary greatly between samples. The magnetic structure has been determined to have P6/m symmetry with k = (0,0,0) with a total moment
of 0.413 μB/Cr3+. There is uniaxial negative thermal expansion along the c axis and a previously undiscovered structural transition at 135 K is observed. It is also determined that Ba1–pCr2Se4–p
is a p-type semiconductor with a high resistivity owed to hopping of the charge carriers but with very low thermal conductivity.
Chapter 5 aims to ascertain the cause of the phase coexistence in the lacunar spinel GaMo4Se8 below its Jahn-Teller transition. It is found that the strain of the dominant R3m phase is large and so is relieved by a partial distortion to the metastable Imm2 phase, which is determined to likely be insulating with charge-ordering of ions, in contrast to the R3m phase which is likely itinerant
and charge-disordered. Single domain crystals are grown, on which magnetisation measurements determine the critical behaviour at the Curie temperature, with critical exponents of β = 0.22(4), γ = 1.19(1) and δ = 6.42(1) not belonging to any one universality class. Magnetoentropic mapping confirms the existence of at least three different non-collinear magnetic phases below the Curie temperature, including a Néel-type skyrmion lattice.
Chapter 6 scrutinises the PbFCl-like structure and disorder of magneto-caloric candidate material MnZnSb. In some powder diffraction patterns, there are unusual, asymmetric peak shapes that are fit with a reduction of symmetry to a triclinic cell. In another sample, it is apparent that Rietveld refinements are greatly improved with the inclusion of a partially occupied, Zn containing interstitial site. In variable temperature data, the cell volume changes significantly at the near room temperature magnetic transition, which is identified as a big contributor to the large change in entropy there. It is also theorised that due to differences in diffraction data and results from magneto-caloric calculations, that samples first exist in a metastable triclinic state which then becomes the tetragonal state over time
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
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