1,721,063 research outputs found
Physical description of Lg waves in inhomogeneous continental crust
No full textThe view of L g waves as a superposition of seismic surface waves is very useful for explaining the amplitudes of the late parts of seismograms from regional earthquakes. We have recently made computations for Rayleigh waves, interpreting the special attenuation of L g waves in the North Sea as being caused by (1) the distribution of energy over longer time intervals, combined with (2) the upwards or downwards pumping of wave energy in the different crustal structures, combined with (3) anelastic absorption.
No special discussion is necessary of the claim that anelastic absorption in a particular area gives a reduction in wave amplitude, whilst a physical description of the geometrical effect is warranted. A physical description of the wave propagation phenomena involved is given in the present paper by classifying the mode conversion that is involved in the propagation from one crustal structure into another. The physics is described via relations between the phase velocities, group velocities and energy dependences on depths of the various surface wave modes that exist in the different crustal structures. We introduce the concept of energy–depth similarity, a parameter that is almost as easily computed as the ratios of phase velocities or group velocities, but is a far better measure of the transition character. The crustal structures in question are representative of (1) the North Sea and its surroundings in general, and (2) the Viking and Central grabens in the middle of the North Sea.
Wave propagation is fundamentally different for different wave frequencies; it is coherent for long-period waves and incoherent for short-period waves. The propagation may generally be termed well-behaved for wave periods longer than several seconds; that is, energy cross-coupling between incoming and outgoing modes follows some regular pattern. This regularity is highly dependent on the similarity of the two modes on either side of a discontinuity, and also on the similarity of their neighbouring modes. A characteristic of the regularity is that there is no mode conversion for very long- period modes. In contrast, a pattern cannot be recognized for waves of shorter period, and one may use the term ill-behaved. The L g waves in the continental crust are in the short-period range because their wavelengths are short compared to thickness changes as well as to the thicknesses of crustal structures. This leads to the view that L g waves are superpositions of many modes, changing into even more modes at any discontinuity. Since Rayleigh and Love waves are coupled at non-perpendicular incidence and the Earth has many discontinuities, the superposition of modes is constantly changing in relative proportions, Rayleigh and Love modes being intermingled
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
Developments toward computations of synthetic seismograms in laterally inhomogeneous anelastic media
No full textDevelopments toward computations of synthetic seismograms in laterally inhomogeneous anelastic media
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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