1,720,962 research outputs found
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
Ion bombardment of crystals and its applications
No full textThe damage characteristics of crystal structures have been studied by ion irradiation using 3 MeV and 150 keV inert gas ions. The diamond structure of C, Si and Ge, zinc-blende structure of GaAs and InSb, and wurtzite structure of InN, GaN and AlN have been examined. For diamond the (111) x-ray diffraction peak is observed to broaden and shift toward lower angles; the lattice expansion, da/a\sb o approaches limiting values with increasing ion fluence (10-30 ion/nm\sp2), consistent with a model based on displacement involving a dynamic equilibrium between the production and the radiation-annealing of the defects. The average volume increment per defect is determined to be 13 2 10\sp{-4} nm\sp3. The x-ray diffraction peaks of Si, Ge, GaAs and InSb do not shift or broaden significantly with ion irradiation but decrease in intensity with increasing ion fluence, consistent with a two-phase model, one crystalline and the other non-crystalline. The curve of I\sb{\rm F}/I\sb o versus fluence can be expressed by I\sb{\rm F}/I\sb o = e\sp{-D\sb{M}F}, where I\sb o and I\sb{\rm F} are x-ray diffraction intensities before and after irradiation at fluence F; D\sb{\rm M} is defined as the metamict damage cross-section. The damage cross-section of Ge to argon (3 MeV) ions is 0.35 0.05 nm\sp2 and 1.0 0.2 nm\sp2 for Kr (3 MeV) ions. Silicon has a damage cross-section of 0.15 0.10 nm\sp2 for Kr (3 MeV) ions. The damage cross-sections for GaAs and InSb to Kr (3 MeV) ions are 0.2 0.10 and 0.40 0.15 nm\sp2, respectively. The response of GaN, AlN and InN to ion irradiation were dramatically different. GaN and AlN do not appear to become damaged, while InN decomposed under ion bombardment. When InN is irradiated by (3 MeV) Kr ions on a W substrate, indium tungstate is formed. By contract, bombardment at 150 keV results in decomposition but no further reaction. The formation of indium tungstate is due to an ion beam mixing reaction induced by the ions of energy 3 MeV. Powder mixtures are difficult to analyze since they give complex x-ray diffraction patterns. The differential changes in the x-ray diffraction patterns of a powder mixture after ion bombardment can be used to distinguish the separate components unambiguously
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
Structure Damage in Zircon by Bombarding Ions
No full textRadiation damage in zircon has been carried out by bombarding with Ne, Ar, Kr or Xe ions of energy 1-3 MeV. The intensities of the x-ray diffraction peaks of damaged zircon decrease exponentially with fluence without changing angular position or peak width. This implies a simple model of damage mechanism and permits the definition of the damage cross-section, DM, by formula Where IF and I0 are corrected x-ray diffraction intensities at fluence F and O respectively. The damage cross-sections of zircon are found to increase with atomic number and the energy of the bombarding ions. The morphological changes due to irradiation are observed by SEM, when micrographs of the same field of view are taken before and after irradiation. At high fluence, the irradiated particles increase in size and become glass-like in appearance. This may be due to swelling of the damaged structure by the absorption of the bombarding ions as a gas, or by a radiation creep process
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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