1,720,962 research outputs found
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
Synthesis and enzymatic post-modification of chiral polymers
Get PDFSmart materials, which respond to external stimuli, are well known for a long time. Typically these materials undergo an (ir)reversible property change upon exposure to an external stimulus. In the majority of cases the stimulus is a change in temperature, pH or is light induced. A relatively new concept that was recently developed involves smart materials that produce a change in response to the action of an enzyme, so called Enzyme Responsive Materials (ERMs). The response that the ERM produces can be any of a wide range of changes such as a change in fluorescence, the release of a drug or the generation of some form of physical aggregation such as the formation of micelles. Enzymes do not only exhibit regio-selectivity but they generally exhibit extremely high stereo-selectivity as well, i.e. the enzyme exclusively acts on one enantiomeric form of a molecule whilst leaving the other enantiomer untouched. Our approach to ERM synthesis is based on this principle, where the extent of the response that the ERM produces to the enzyme is encoded within the chirality of the material. By using different ratios of the enantiomers (building blocks) within the ERM, the extent of the response can be programmed-in without causing any changes in the general physical properties of the material. With this principle in mind, a number of acetophenone-derivatives with different functional groups in the para-position of the phenyl ring were synthesized (Chapter 2). In an attempt to reduce these prochiral ketones to their enantiomeric forms by employing two commercially available alcohol dehydrogenases (ADHs), namely (R)-producing Lactobacillus (ADH-LB) and (S)-producing Thermoanaerobacter sp. (ADH-T) as the catalysts for the reductions, a significant difference in the substrate acceptance by these enzymes was observed despite claims concerning their broad substrate spectrum. The examination of the various factors such as the solubility of the substrate in the reaction medium, the size of the substrate and the electronic character of the substituent at the para-position of the acetophenone derivatives did not offer any trend to explain the difference in the substrate acceptance by ADH-LB and ADH-T. Instead, we realized that non-polar para-substituents were favored over polar or ionizable para-substituents in the reductions. Mapping of the electronic charge distribution in the molecules revealed a correlation between the location of the highest electron density on the molecule and the success of the reaction. The substrates with the highest electron density on the carbonyl group could be reduced almost quantitatively to their enantiomeric forms. However, if the highest electron density is located on a different functional group of the substrate, then the substrate could not be reduced. ADH-catalyzed reduction of acetophenone-derivatives resulted in the synthesis of two types of enantiopure building blocks having an enzyme sensitive unit (phenyl ethanol): one with a polymerizable group, ((R)- and (S)-1-(4-vinylphenyl)ethanol), and the other one with a clickable moiety, ((R)- and (S)-1-(4-ethynylphenyl)ethanol). In chapter 3, homo and copolymers were synthesized from enantiopure (R)- and (S)-1-(4-vinylphenyl)ethanol and styrene by RAFT (co)polymerization. Well-defined polymers with low polydispersities were obtained. Kinetic investigations confirmed that the enantiopure monomers and styrene have similar reactivity ratios resulting in random copolymers. In chapter 4, block copolymers comprising two blocks with pendant hydroxy groups of opposite chirality were synthesized in which the length of starting block, (R)-block, was kept constant at 7,200 g/mol. The length of the second block, (S)-block, was varied from 2,100 to 6,400 g/mol. The optical rotation decreased from 29.8° to 1.5° with increasing (S)- to (R)- block length ratio. Noteworthy is that the blocky character of these chiral polymers would only manifest itself in the optical rotation since it is reasonable to claim that the chemical and physical properties of the individual chiral (S)- and (R)-blocks are identical. In chapter 5, linear and star-shaped poly(n-butyl acrylate)s (BAs) were prepared via ATRP of n-butyl acrylate by employing different ATRP initiators. Consecutive click reactions with (R)-1-(4-ethynylphenyl) ethanol after the chain end functionalization with an azide were not quantitative, probably due to loss of some of the end groups. In addition, chiral dendrimers were prepared from different mixtures of (R)- and (S)-1-(4-ethynylphenyl)ethanol, and the matching azide-functional bisMPA dendrimers using click chemistry. The specific optical rotation of the dendrimers increased linearly with increasing percentage of (R) end-groups in the dendrimer, which indicates that (R)- and (S)-building blocks had been incorporated into the dendrimer in agreement with the enantiomeric feed ratio in the click reaction. The molar rotation values of the dendrimers were found to be directly proportional to the number of (R)-building blocks clicked to the periphery, implying that each stereogenic group at the periphery behaves like an isolated molecule and does not induce any additional chiral substructure. Prior to the exposure of the synthesized chiral polymers to Candida Antarctica Lipase B to study the response of these macromolecules to an enantioselective enzyme, model reactions were performed to investigate the optimal reaction conditions. Since the chiral homopolymers synthesized in this study were not soluble in common hydrophobic solvents like hexane or toluene, in which CALB generally shows optimum activity, different organic solvent systems, both polar as well as mixtures of polar and apolar solvents, were employed for the CALB-mediated esterification of phenylethanol units with vinylacetate. Toluene/THF (2/1 v/v) was found to be the most appropriate solvent mixture for the post-functionalization of (R)-polymer. It was shown that the lipase-catalyzed polymer analogous esterification of the chiral hydroxy groups was strongly (R)-selective, in agreement with the preferred lipase enantioselectivity. However, even after extended reaction times, esterification on the (R)-polymers was limited to around 50 %, which was much lower than the results obtained with small model compounds. Increasing the molecular weight of (R)-polymers from 5,400 g/mol to 16,200 g/mol resulted in a decrease of the esterification yield (55 % to 42 %). This suggests that steric factors play a role in the esterification, although it cannot be ruled out that a decrease of polymer solubility in toluene/THF (2/1) with increasing molecular weight also contributes to this result. When (R)-1-(4-vinylphenyl)ethanol-styrene copolymers with different chirality were exposed to CALB, an increase in the extent of esterification (from 21 to 53 %) was observed whilst the composition ratio of (R)- 1-(4-vinylphenyl)ethanol/styrene was increased from 0.25 to 4. However, further increase in the enzyme-sensitive monomer concentration in the backbone did not further improve the extent of esterification (the maximum reached in these conditions with homopolymer was 55 %). This might suggest that not only steric effects play a role but that possibly also the local environment of the hydroxy groups is important for the extent of the reaction. CALB-catalyzed esterification of the chiral block copolymers was stereoselective and only one of the present blocks was esterified, thereby converting these chiral block copolymers into block copolymers with chemically and physically distinguishable blocks. CALB-catalyzed esterification of these (R)-phenyl ethanol groups at the chain end of polyBAs was successful and principally validated the proposed strategy of enantioselective enzymatic esterification of globular multifunctional chiral materials. The extremely high selectivity of CALB towards the R enantiomer of the 1-phenyl-ethanol moiety was retained also on the periphery of dendrimers. Furthermore, the chirality of the dendrimer directly correlates to a chemical reaction yield using an enantioselective catalyst. In the last chapter, vinyl methacrylate was used as the acyl donor in the CALB-catalyzed post-polymerization modification of selected (R)-chiral polymers as a comparison to vinyl acetate. These modifications provided pendant methacrylic double bonds which were utilized in thiol-ene reactions, viz. the Michael addition of poly(ethylene glycol) methyl ether thiol (PEG-SH), for further modification. The preliminary results showed that vinyl methacrylate could be used successfully as the acyl donor in the CALB-catalyzed esterifications. However, the extent of the esterification of pendant (R)-OHs with vinyl methacrylate was lower (35 %) compared to that with vinyl acetate (55%) performed under the same reaction conditions. In conclusion, the proof of principle described in this dissertation can be employed to program reactivity into otherwise indistinguishable molecules. It can be stated that chirality can be used as a means of encoding macromolecules that and a key characteristic of enzymes, i.e. enantioselectivity, can be utilized to read-out this code by correlating it to a chemical reaction
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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