1,720,963 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
Nat Cell Biol
Get PDFThe size of a typical eukaryotic cell is of the order of \ue2\u2c6\ubc10\ue2\u20ac\u2030\uce\ubcm. However, some cell types grow to very large sizes, including oocytes (immature eggs) of organisms from humans to starfish. For example, oocytes of the frog Xenopus laevis grow to a diameter \ue2\u2030\ua51\ue2\u20ac\u2030mm. They have a correspondingly large nucleus (germinal vesicle) of \ue2\u2c6\ubc450\ue2\u20ac\u2030\uce\ubcm in diameter, which is similar to smaller somatic nuclei, but contains a significantly higher concentration of actin. The form and structure of this nuclear actin remain controversial, and its potential mechanical role within these large nuclei is unknown. Here, we use a microrheology and quantitative imaging approach to show that germinal vesicles contain an elastic F-actin scaffold that mechanically stabilizes these large nuclei against gravitational forces, which are usually considered negligible within cells. We find that on actin disruption, ribonucleoprotein droplets, including nucleoli and histone locus bodies, undergo gravitational sedimentation and fusion. We develop a model that reveals how gravity becomes an increasingly potent force as cells and their nuclei grow larger than \ue2\u2c6\ubc10\ue2\u20ac\u2030\uce\ubcm, explaining the requirement for a stabilizing nuclear F-actin scaffold in large Xenopus oocytes. All life forms are subject to gravity, and our results may have broad implications for cell growth and size control.1DP2GM105437-01/DP/NCCDPHP CDC HHS/United StatesDP2 GM105437/GM/NIGMS NIH HHS/United States2014-04-01T00:00:00Z23995731PMC378985
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
Mechanics of Cell Growth
No full textOrganisms vary in size by orders of magnitude spanning 1 μm to hundreds of meters, yet their cells remain on the micron length scale. The physical mechanisms that control the size of cells remain unclear. Here, I study the extraordinarily large oocytes (immature eggs) from the frog Xenopus laevis to understand how cell organization and mechanics change as these cells grow to reach sizes of 1 mm. I discover that these oocytes have evolved to contain a unique nuclear actin meshwork that supports the liquid-like nuclear bodies from gravitational sedimentation and mass fusion events. I find that gravitational forces on organelles dominate random thermal forces for cell sizes greater than ~100 μm, suggesting that large cells require novel mechanisms to maintain proper spatial organization. Directly probing the material properties with active microrheology, I find that nuclear actin forms a soft viscoelastic network that is capable of undergoing gravitational creep on the time scale of growth. This suggests that the material properties of nuclear actin are matched to its mechanical role in kinetically stabilizing an emulsion of nuclear bodies during growth. For forces higher than 1 g and for longer times, these nuclear bodies will undergo significant displacements in the nucleus due to gravitational creep, thereby disrupting proper cellular organization. Although these nuclear bodies are known to behave as liquids, it still remains unknown how they maintain three distinct compartments. Visualizing nuclear actin shows protrusion of filaments inside these nuclear bodies in between different compartments, and by disrupting nuclear actin, I find that these compartments are able to rearrange and undergo homotypic fusion events. In combination with in vitro approaches, I determine that each nucleolar compartment represents a distinct liquid-like phase, and these nuclear bodies are thus behaving as multiphase droplets. Principles from liquid-liquid phase transitions provide a physical framework for organization even within organelles. Overall, X. laevis oocytes are an example of how cells can evolve to reach large sizes. Simple biophysical mechanisms can allow cells to maintain structural organization, even on length scales ~1,000 times their typical size
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
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