1,720,965 research outputs found
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
Development of separation methods to produce uniform exosomes subpopulations using field-flow fractionation techniques
No full text2015 Spring.Includes illustrations (some color).Includes bibliographical references (pages 143-161).Exosomes are nanometer-sized vesicles (30-120 nm) with a defined density range (1.08-1.22 g/cm3), secreted by most cells in the body, including tumors. Exosomes contain specific proteins, lipids, and functional microRNA (miRNA) and messenger RNA (mRNA) that can be transferred from cell to cell which suggests a role in cell-to-cell communication. Despite the tremendous strides that have been made in the last years toward understanding the properties and function of exosomes, this goal remains a challenging task. Exosomes have a potential role in early diagnosis of cancer but recent reports suggest controversial activities in cancer therapy. Exosomes have an anti-tumorigenic ability by priming the immune system. However, other studies have demonstrated that exosomes can stimulate tumor growth and metastasis and promote cancer resistance to chemotherapeutic drugs. This paradox may be the result of heterogeneity and contaminants in exosomes preparations and highlights the need for standardized protocols. Ultracentrifugation is the most common isolation technique used for exosomes, but preparations obtained by this method frequently contain other extracellular vesicles such as microvesicles and apoptotic bodies that overlap in densities and sizes with exosomes. This doctoral work seeks to address this challenge by demonstrating the ability of field-flow fractionation (FFF) techniques to be used as an orthogonal approach, along with the primary ultracentrifugation method, to remove non-exosomal byproducts and to produce and characterize homogenous exosomes subpopulations. This thesis involves three main projects with a general aim to design FFF approaches that have the capability to meet the challenges in exosomes separation and analysis. The first project aims to develop optimized sedimentation FFF (SdFFF) and asymmetric flow FFF (AF4) to produce effective mass- and size-uniform exosomes subpopulations from heterogeneous exosomes preparations that were derived from various tumor cell lines (e.g., breast, brain, and ovarian cancers) using ultracentrifugation. Fractions collected at the outlet of the FFF channel are characterized with respect to density and size. The SdFFF, which is an effective mass meff based separation technique, was first used to produce meff uniform fractions. The meff is equal to d3[Delta][rho] where d is diameter and [Delta][rho] is the difference in density between the particle and the carrier liquid. The density distribution of breast cancer ascites exosomes was found to be ~1.01 to 1.18 g/cm3, suggesting that exosomes preparations from ultracentrifugation were contained low density contaminants (in the lower SdFFF fractions) that can be eliminated and separated from exosomes fractions (in the higher SdFFF fractions). The exosomes were also introduced into anAF4 system where they underwent a size separation. AF4 demonstrated the ability to narrow the original size distribution of the exosomes from ~ 30-500 nm to ~ 30-140 nm. Furthermore, each exosomal fraction has a narrow size distribution of approximately ± 10 nm. While SdFFF and AF4 were independently implemented in the first project, the second project focused on a novel two-dimensional approach wherein both techniques were used to obtain uniform mass and size subpopulations. Exosomes from different cancer cell lines are first separated using SdFFF and fractions with uniform meff were collected. Each SdFFF fraction with uniform meff is then injected into an AF4 channel and a size separation was implemented. Hence, each fraction that is collected at theAF4 outlet has a uniform d and density. An online focusing stage commonly used in AF4 solves the sample dilution problem encountered when conducting two-dimensional separations. Assessment of separated exosome fractions confirmed that the fractions are indeed uniform in density and size. The average densities of the exosomes fractions after two-dimensional FFF were determined to be between ~ 1.05 to 1.10 g/cm3. These results suggest that non-exosomes components of low densities can be fractionated from exosomes of higher densities. The sizes of exosomes in fractions collected after two-dimensional FFF are determined using dynamic light scattering and ranged from ~ 40 to 80 nm for brain cancer exosomes, ~ 40 to 140 nm for ovarian cancer exosomes and ~ 50 to 145 nm breast ascites exosomes. These ranges, which span the exosomes sizes, represent narrower size distributions than that of the unfractionated exosomes sample. The third project was designed to improve the sample throughput by scaling up the analytical AF4 channel to a semi-preparative AF4 (sP-AF4) channel. Results from this study showed that the brain cancer-derived exosomes sample volume can be increased up to 250 fold to produce ~ 75 [mu]g of exosomes per fraction using a sP-AF4 channel without affecting the resolution of the separation. This allowed the production of large amounts of size uniform exosomes subpopulations with one sample injection, rather than performing tens of experiments on an analytical channel to collect and concentrate combined fractions. Characterizing the exosomes fractions collected from the sP-AF4 channel shows that the fractions have distinct sizes that range from ~ 40 to 150 nm. Exosomes fractions also showed an abundance of proteins with molecular weights between ~ 60 and 70 kDa. The presence of common exosomal protein biomarkers including CD9, Hsp/c70, and Hsp90 in each sP-AF4 fraction was confirmed by Western blot analysis. The results showed that most of the fractions contained different relative concentrations of exosomal protein biomarkers, indicating the presence of exosomes. The data presented in this thesis advances the separation and characterization of exosomes and establishes a route forward towards obtaining purer exosomes preparations and subpopulations. This capability stands to contribute significantly to furthering the understanding of the role of exosomes in intracellular communication, and to assess their potential role and use in cancer diagnosis and progression
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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