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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
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Synthesis, Characterization and Reactivity of Organometallic Complexes of Uranium and Plutonium in the +2 and +3 Oxidation States
Get PDFSynthesis, Characterization and Reactivity of Organometallic Complexes of Uranium and Plutonium in the +2 and +3 Oxidation StatesByCory J. WindorffDoctor of Philosophy in ChemistryUniversity of California, Irvine, 2017Professor William J. Evans, ChairThis dissertation focuses on the synthesis, characterization, and reactivity of unique organometallic complexes of uranium, plutonium, and the lanthanides in efforts to expand the limits of known redox chemistry of these elements. The results in this dissertation extend investigations of previously established reduction reactions involving these metal ions to extend them to more challenging systems. These reactions utilized the tri(cyclopentadienide) coordination environment examining the differences in the substitution pattern on the cyclopentadienide rings, particularly the Cp′′ ligand [Cp′′ = C5H3(SiMe3)–1,3]. In the course of these studies, the +2 oxidation state for plutonium was confirmed, and the most stable form of UII to date was isolated. To accomplish the plutonium chemistry, several surrogate syntheses were performed using lanthanides of similar size and reactivity to that of plutonium, namely cerium and neodymium. These experiments examined the electronic structure to compare and contrast the +2 oxidation state across the actinide series. In Chapter 1 29Si NMR spectra were recorded for a series of uranium complexes containing silicon and the data have been combined with results in the literature to determine if any trends exist between chemical shift and structure, ligand type, or oxidation state. Data on 48 paramagnetic inorganic and organometallic uranium complexes are presented. The survey reveals that although there is some overlap in the range of shifts of UIV complexes versus UIII complexes. In general UIII species have more negative shifts than their UIV analogs. The single UII example has the most negative shift of all at −322 ppm at 170 K. With only a few exceptions, UIV complexes have shifts between 0 and −150 ppm (vs. SiMe4) whereas UIII complexes resonate between −120 and −250 ppm. The small data set on UV species exhibits a broad 250 ppm range centered near 40 ppm. The data also show that aromatic ligands such as cyclopentadienide, cyclooctatetraenide, and the pentalene dianion, exhibit less negative chemical shifts than other types of ligands. Chapter 2 describes the synthesis of new molecular complexes of UII that were pursued to make comparisons in structure, physical properties, and reactivity with the first UII complex, [K(crypt)][Cp′3U], 21-U (Cp′ = C5H4SiMe3, crypt = 2.2.2-Cryptand). Reduction of Cp′′3U, 20-U, [Cp′′ = C5H3(SiMe3)2–1,3] with KC8 in the presence of crypt or 18-crown-6 generates [K(crypt)][Cp′′3U], 22-U, or [K(18-crown-6)(THF)2][Cp′′3U], 23-U, respectively. The UV/vis spectra of 22-U and 21-U are similar, and they are much more intense than those of UIII analogs. Variable temperature magnetic susceptibility data for 21-U and 22-U reveal a lower room temperature χMT value relative to the experimental value for the 5f 3 UIII precursors. Stability studies monitored by UV/vis spectroscopy show that 22-U and 23-U have t1/2 values of 20 and 15 h at room temperature, respectively, vs 1.5 h for 21-U. Complex 23-U reacts with H2 or PhSiH3 to form the uranium hydride, [K(18-crown-6)(THF)2][Cp′′3UH], 26. 21-U and 23-U both reduce cyclooctatetraene to form uranocene, (C8H8)2U, as well as the UIII byproducts [K(crypt)][Cp′4U], 28-U, and Cp′′3U, 20-U, respectively. In Chapter 3 Cp′4U, 37-U, was synthesized from (a) KCp′ and [Cp′3U(THF)][BPh4], 36, (b) Cp′3U, 8-U, and Cp′2Pb,30, and (c) [K(crypt)][Cp′4U], 28-U, and AgBPh4 and identified by X-ray crystallography as a rare example of a structurally-characterized tetrakis(cyclopentadienyl)UIV complex. The corresponding Th complex, Cp′4Th, 37-Th, was obtained from the direct combination of ThBr4(THF)4 with excess KCp′ in low yield. During the preparation of Cp′3UMe, 35, the precursor of the [Cp′3U(THF)][BPh4], 36, reagent used above, it was discovered that the reaction of Cp′3UCl, 33-U, and MeLi gives a mixture of Cp′3UMe, 35 and 33-U that can co-crystallize better than 35 in pure form. Although 35 typically is an oil, a mixture of 35 and 33-U forms single crystals that are suitable for X-ray crystallography and contain a 4:1 ratio of the compounds. Hence, forming a mixture provided a new way to get structural data on the oil, 35. 33-U and Cp′3UI, 34, were also crystallographically characterized for comparison with the Cp′3UMe/Cp′3UCl, 35/33 crystals. Chapter 4 examines the optimization of reaction conditions for milligram scale plutonium reactions. Starting from the metal, small-scale reactions of the Pu surrogates, La, Ce, and Nd, were explored. Oxidation of these lanthanide metals with iodine in ether or pyridine was studied and it was found that LnI3(Et2O)x, 39-Ln (x = 1.5–1.8), and LnI3(py)4, 40-Ln (py = pyridine, NC5H5), can be synthesized on scales ranging from 15 mg to 2 g. The THF adducts LnI3(THF)4, 41-Ln, were synthesized by dissolving 39-Ln in THF which was found to be preferable to synthesis from the metal in THF on this small scale. The viability of these small scale samples as starting materials for amide and cyclopentadienyl f–element complexes was tested by reacting in situ generated 39-Ln with KN(SiMe3)2, KCp′, Cp′′, and KC5Me4H. This produced Ln[N(SiMe3)2]3, 15-Ln, Cp′3Ln, 8-Ln, Cp′′3Ln, 20-Ln, and (C5Me4H)3Ln, 32-Ln. Small scale samples of Cp′3Ce, 8-Ce, and Cp′3Nd, 8-Nd, were reduced with potassium graphite (KC8) in the presence of crypt to check the viability for generation of crystallographically-characterizable LnII complexes, [K(crypt)][Cp′3Ln], 21-Ln (Ln = Ce, Nd). Similar reactions of Cp′′3Nd, 20-Nd, with KC8 in the presence of crypt gave [K(crypt)][Cp′′3Nd], 22-Nd, as a crystallographically characterizable complex.Chapter 5 combines and extends the chemistry described in Chapters 2 and 4 to plutonium. Over seventy years of chemical investigations have shown plutonium exhibits some of the most complicated chemistry in the periodic table. Six Pu oxidation states have been unambiguously confirmed (0, +3 to +7) and five different oxidation states can exist simultaneously in solution. The synthesis and characterization of a new formal oxidation state for plutonium, namely PuII in [K(crypt)][Cp′′3Pu], 22-Pu, is examined. The synthetic precursor, Cp′′3Pu, 20-Pu, is also synthesized and discussed, comprising the first structural characterization of a Pu–C bond. Absorption spectroscopy and DFT calculations indicate that the PuII ion has predominantly a 5f 6 electron configuration with some 6d-mixing. Reactivity studies show that 22-Pu reacts with AgBPh4 to reform 20-Pu in high yield
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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