1,721,118 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
Distribution, structure, and formation of Holocene lava shields in Iceland
No full textLava shields in Iceland are monogenic shield volcanoes mostly composed of primitive basalts, picrite and olivine tholeiite. The Holocene shields are restricted in space and time: in space they are essentially confined to the North and West Volcanic Zones; in time they are essentially confined to the early part of the Holocene. The volcanic zones are characterised by volcanic systems, that is, 5-20 km wide and 40-150 km long swarms of tectonic fractures and volcanic fissures where most of the Holocene volcanotectonic activity takes place. However, most lava shields are not located inside the volcanic systems but rather at their margins or in between systems. In addition to the lavas of the shields being more primitive than those issued from nearby volcanic fissures, the average volume of a shield is an order of a magnitude larger than that of the lava from a fissure. Here we present the results of new field observations of Holocene shields and provide numerical models to explain their location, time of formation, primitive composition, and large volumes. We made models with varying ice-sheet size and thickness (glacial load), the ice resting on a mechanically layered crust, and studied the stress effects that the load would have on a double magma chamber, that is, a small, shallow crustal chamber at 3 kin depth and a deep-seated reservoir at 20 kin depth (the base of the crust). Such a pair of chambers is typical for volcanic systems and associated central volcanoes (composite volcanoes) in Iceland. For an ice sheet covering an entire volcanic zone or more, that is, 100 kin or wider, the ice-induced compressive stress extends to the deep-seated reservoir and into the upper mantle. Consequently, such a loading suppresses magma accumulation in the reservoir and associated volcanism. During the late-glacial period, when the ice sheet is only 20 kin wide, the glacial load generates tensile stresses around the deep-seated reservoir, increases its fracture porosity and magma content, and extends the reservoir laterally and vertically into the upper mantle. Consequently, when the lava shields (and, somewhat earlier, the tablemountains) were erupted, much more melt or magma was available to feed a single eruption than during the later part of the Holocene. And because of the greater vertical extent of the reservoir, this magma tended to be hotter and more primitive than that issued in later-formed fissure eruptions. Also, the stress field generated at the end of the glacial and in the early Holocene favoured dyke injections at the marginal parts of, or in between, the volcanic systems, thereby explaining the location of the lava shields. (c) 2007 Elsevier B.V. All rights reserved
Mechanical interaction between active volcanoes in Iceland
No full textWe test the possibility of mechanical interaction between eight central volcanoes in the central part of the active Iceland rift zone. The average distance between the volcanoes is 30 km; all are thought to have shallow magma chambers, and many contain collapse calderas. We analyzed many finite-element models with the volcanoes subject to a tensile stress of 5 MPa ( equal to the maximum in situ tensile strength of the crust) in a direction parallel to the spreading vector, N105 degrees E. The results show zones between many nearby volcanoes where the tensile stresses exceed the in situ tensile strength of the crust. The results indicate that mechanical interaction between volcanoes in a pair, such as simultaneous dike emplacement, seismogenic faulting, and deformation, may be common in this part of Iceland, in agreement with observations
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
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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