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Environmental and noise signals in terrestrial gravimetry
Get PDFObservations of time-variable gravity from terrestrial gravimeters have many applications, ranging from studies of Earth tides and volcanoes to modern redefinitions of the kilogram. Via three studies, this dissertation contributes to two areas of terrestrial gravimetry: study of environmental processes using terrestrial gravimeter observations, and mitigation of non-gravitational (noise) sources that contaminate terrestrial gravimeter observations. In the first study, we characterize environmental gravity variations at McDonald Observatory, in West Texas, using 3.5 years of superconducting gravimeter observations. Our objectives are: 1) to develop and assess gravity models of tides, atmospheric loading, and terrestrial hydrology for the site using SG observations; and 2) to enable more precise environmental correction of gravity and other geodetic observations at the site. From superconducting gravimeter observations, we generate an empirical tide model in the diurnal and semi-diurnal band. The empirical tide model differs by up to 2 µGal (1 µGal = 10⁻⁸ m/s²) from conventional tide models, suggesting mismodeling of regional air loads or ocean tides in conventional models, and/or instrument calibration error. Atmospheric loading and attraction is optimally modeled by a local barometric admittance of -0.25 µGal/mbar, or 16% below the conventional estimate, likely due to high site elevation. Predicted hydrologic loading and attraction generated from land and atmosphere reanalyses MERRA-2 and ERA5-Land aligns temporally with observed gravity change and local rain gauge data. Differences in magnitude between hydrologic predictions and observed gravity change might be explained by unmodeled local water loads, at spatial scales below model resolution. We suggest future work on modeling and studying local-scale hydrology using gravity and in-situ hydrologic datasets. The second and third studies are targeted investigations of noise sources that affect the most common absolute gravimeter, called the FG5. Observations from this gravimeter are used widely in many defense and science contexts. We contribute to ongoing efforts to eliminate bias and reduce scatter of its gravity estimates. In the second study, we profile newly-discovered FG5 noise, dubbed a spatial wave, that is thought to originate from uneven rotation of a pulley within the instrument. This noise might systematically bias gravity estimates by up to 1 µGal. We introduce methods to fully characterize and correct this error source. We demonstrate these methods on FG5 data from a Texas coastal site, and find that the spatial wave imparts a very small bias (0.1 µGal) on the final gravity estimate. We also discover two new spatial waves at higher frequencies. We determine by simulation that these new waves negligibly bias gravity estimates. FG5 operators can use our methods to determine if spatial waves are present in their datasets, to correct observations for a wave, and to assess correction effectiveness. In the third study, we quantify the effect of vibrations on bias and scatter of FG5 gravity estimates. Microseismic vibrations are known noise source affecting FG5 gravity estimates, however sensitivity of gravity estimates to vibrations has not been rigorously quantified for the FG5, as it has been for other gravimeters. Via a case study at a Texas coastal site, we show that a seismometer is a useful tool for studying and mitigating vibration contamination of FG5 gravity estimates. From seismic data, we identify environmental vibrational sources (wind, ocean, and human) and instrument-generated vibrations. We quantify sensitivity of gravity estimate scatter to vibrations in different frequency bands. From this we infer that FG5 gravity estimates are most sensitive to seismic vibrations in the 0.1-10 Hz band. We also develop methods for correcting gravity estimates for vibrations using seismic data. One of these methods is highly successful; it reduces gravity estimate scatter at our site by 34% and changes the mean gravity estimate by -0.6 µGal. Using the methods described, FG5 operators might deploy a seismometer to guide site selection and to predict and minimize the effects of vibrational noise.Earth and Planetary Science
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
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
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
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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