1,720,965 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
Identification of novel marine algal compounds with differential anti-cancer activity : towards a cancer stem-cell specific chemotherapy
No full textBreast cancer remains the leading cause of cancer-related death in women worldwide.
Furthermore, it has been demonstrated that the treatment-resistant ER-PR-HER2/neu- sub-type
is more common among women of African descent, necessitating the search for novel
chemotherapies for this form of the disease. The secondary metabolites produced by marine
algae represent a rich source of structurally unique compounds with chemotherapeutic
potential, particularly in South Africa, whose oceans allegedly host 15 % of the total number of
species in the world. Indeed, a recent study reported the isolation of a range of novel
compounds from South African red and brown algae of the Plocamium, Portiera and Sargassum
genera which displayed cytotoxicity against oesophageal cancer cells in vitro. The molecular
mechanisms mediating this toxicity were unknown, as was the effect of these and similar
compounds on metastatic ER-PR-HER2/neu- breast cancer cell lines or breast cancer stem cells.
The current study aimed to address these questions by screening a library of twenty-two novel
marine algal compounds for the ability to inhibit MDA-MB-231 and Hs578T breast cancer cells,
while having no adverse effects on non-cancerous MCF12A breast epithelial cells. While twelve
of these were toxic in the micromolar range against breast cancer cells, only the
polyhalogenated monoterpenes RU004 and RU007, and the tetraprenylated quinone
sargaquinoic acid (SQA) were identified as hit compounds based on the criteria that their
cytotoxicity was specific to breast cancer and not healthy breast cells in vitro. On the other
hand, the halogenated monoterpene RU015 was found to be highly toxic to both breast cancer
and non-cancerous breast cell lines, while the halogenated monoterpene stereoisomers RU017
and RU018 were non-toxic to either of these cell lines.
The mode of action of RU004, RU007, RU015 and SQA, together with the previously
characterized carotenoid fucoxanthin (FXN), was assessed in terms of the type of cell death
induced and the effect on cell cycle distribution of these compounds. Flow cytometric analysis
of the extent of Hoescht 33342 and propidium iodide staining along with PARP cleavage studies
suggested that SQA induced apoptosis in MDA-MB-231 cells. On the other hand, the highly
toxic compound RU015 appeared to induce necrosis as evidenced by 50 kDa PARP cleavage
product in MDA-MB-231 cells. The flow cytometry profiles of MDA-MB-231 and Hst578T cells
treated with the hit compounds RU004 and RU007 were suggestive of the induction of
apoptosis by these compounds. Cell cycle analysis by flow cytometry with propidium iodide
staining revealed that both SQA and FXN induced G0-G1 arrest together with an increase in the
apoptotic sub-G0 population, which agreed with previous reports in the literature.
The molecular mechanism of action of SQA and FXN were further investigated by the
identification of specific signal transducer molecules involved in mediating their anti-cancer
activities. SQA was found to require the activity of numerous caspases, including caspase-3, -6,
-8, -9, -10 and -13, for its cytotoxicity and was demonstrated to decrease the level of the antiapoptotic
protein Bcl-2. On the other hand, FXN was shown to require caspase-1, -2, -3, -9 and -
10 for its toxicity. This, together with the ability to decrease the levels of Bcl-2, pointed to the
involvement of the intrinsic pathway in particular in mediating the activity of FXN.
The screening of algal compounds against non-cancerous breast epithelial cells carried out in
this study, together with the investigation into their mechanisms of action, represent one of
the few reports in which characterization of algal metabolites goes beyond the initial
cytotoxicity assays.
Finally, in order to assess the potential anti-cancer stem cell activity of the marine algal
compounds, a subset of these was screened using a mammosphere assay technique developed
in this study. The cancer stem cell (CSC) theory proposes that cancers arise from and are
maintained by a specific subpopulation of cells able to undergo asymmetric cell division and
termed CSCs. These CSCs are capable of anchorage-independent growth in serum-free culture
conditions, such as those in the mammosphere assay. Using this assay, the novel halogenated
monoterpene stereoisomers RU017 and RU018 were demonstrated to possess putative anti-
CSC activity as evidenced by their ability to completely eliminate mammosphere formation in
vitro. Furthermore, since RU017 and RU018 were non-toxic to both breast cancer and healthy
breast cells, it appeared that the activity of the compounds was potentially specific to the CSCs.
The results require further validation, but represent the first report of selective anti-CSC
activity
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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