1,720,953 research outputs found
A study of upper mantle anisotropy in Cascadia using teleseismic shear wave delays
Full text linkopenSeismic tomography is one of the most powerful tools available when attempting to characterise the Earth’s interior. Often an underlying assumption of these inversions is one of elastic mantle isotropy, when it is known that anisotropy is present within the upper mantle. Simple shear deformation of the mantle creates lattice-preferred orientation (LPO) of minerals, principally olivine which is an anisotropic mineral. Therefore where an LPO forms we expect a seismically anisotropic upper mantle. When a linearly polarised shear wave (S-wave) encounters this anisotropy it splits into two orthogonal waves with one component polarised along the plane of greatest seismic velocity. Determining the direction of anisotropy can reveal information about deformational history, flow and other properties in the upper mantle. Accounting for anisotropy will lead to more accurate seismic tomography models whilst providing indications of convective flow and structural fabrics within the upper mantle.
The area of this study is the Cascadia Subduction Zone in the Western USA. The relatively young and small Juan de Fuca (JDF) plate is subducting beneath the North American plate at the Cascadia trench. It is a complex geodynamic setting which comprises: JDF ocean ridge, Cascadia trench, forearc between the trench and Cascadia volcanic chain, a back arc region. This is bound to the North and South by triple junctions. This study utilises 593 seismic stations on 25 different networks and data from September 2011 to August 2015. Previous anisotropic S-wave tomography studies have focused mainly on the SKS phase. Conversion from P to S-wave at the core mantle boundary ensured that only anisotropy within the mantle will influence the S-wave arrival. This study instead focuses on 4 different S-wave phases: S, sS, Sdiff and sSdiff.
Teleseismic S-wave arrivals for 383 earthquake events were identified on the transverse channel of the seismic station. Initially the S-wave arrivals were analysed with reference to the AK135 earth reference model. Alignment of the S-waves was undertaken using multichannel cross correlation (MCC). A stacked version of all the S-wave arrivals was created to identify the waveform. The measured delay times and the stacked traces arrival time were combined to calculate the travel time. The stacked traces were then rotated to find the azimuth of the polarisation angle, the angle of maximum S-wave energy arrival. Subsequently a second MCC was completed in the polarisation direction to determine the delay time of the polarised wave, containing information about both isotropic and anisotropic velocity variations along the ray path.
Inverse tomographic modelling was completed using the updated travel times from both the transverse channel and the polarisation channel. Initially a deterministic inversion was utilised to produce 700km deep, 3D S-wave velocity models. For anisotropic inversions, a vector aligned with the axis of symmetry of the hexagonal velocity model was also calculated, allowing a visual representation of anisotropy. Following these results, a set of stochastic inversions based on the reversible jump Markov Chain Monte Carlo (rjMCMC) methodology were completed with the intention of comparing the two inversion methods for the same dataset.
From initial interpretations from both the isotropic and anisotropic deterministic inversion results, the subducting JDF plate can be observed as a steeply dipping fast velocity anomaly. Both models also display evidence of a possible gap within the subducting plate. A roughly horizontal circular pattern in the anisotropy vector at the southern edge of the JDF slab could be interpreted as toroidal mantle return flow caused by slab rollback of the subducting plate. Initial results from the isotropic stochastic inversion are comparable to the deterministic inversions. A stochastic anisotropic inversion is currently being undertaken
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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