1,721,011 research outputs found
Clues on grain size and settling in protoplanetary disks from ALMA polarimetric studies
No full textWe have obtained ALMA polarimetric data at 870 microns (Band 7) and 0."2 resolution for the protoplanetary disks around DG Tau and CW Tau, two T Tauri systems with well known jets. In both targets the results are consistent with dust self-scattering being at the origin of the polarization pattern. The polarization maps highlight structural details not derivable from the analysis of the total emission alone. Such substructures are likely related to changes in the optical depth, and can betray a change in the physical structure of the disk. The measured values of the polarization fraction give constraints to the maximum size of the grains giving rise to observed patterns. This size is found to be in the range 50 - 150 microns in our targets. Meanwhile, the polarization maps combined with dust opacity estimates give constraints on the scale height of such grains. Overall, we find that these grains are larger and more settled toward the midplane in CW Tau than in DG Tau. These results confirm that polarization can be a fundamental complement to observations in total emission, for the investigation of the structure and of the evolution of protoplanetary disks
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
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
ALMA Polarimetry reveals the properties of protoplanetary disks with rotating jets: clues on grains
No full textWe have obtained ALMA polarimetric data at 870 microns (Band 7) and 0."2 resolution for the protoplanetary disks around DG Tau and CW Tau, two T Tauri systems with well known rotating jets. In both targets the results are consistent with dust self-scattering being at the origin of the polarization pattern (Bacciotti et al., 2018, ApJ 865, L12). The polarization maps highlight structural details not derivable from the analysis of the total emission alone. Such substructures are likely related to changes in the optical depth, and can betray a change in the physical structure of the disk. The has been confirmed by subsequent ALMA observations by our group (Podio et al., 2019, A&A 623, L6). The measured values of the polarization fraction give constraints to the maximum size of the grains giving rise to observed patterns. This size is found to be in the range 50 - 150 microns in our targets. Meanwhile, the polarization maps combined with dust opacity estimates give constrai nts on the scale height of such grains. Overall, we find that these grains are larger and more settled toward the midplane in CW Tau than in DG Tau. These results confirm that polarization can be a fundamental complement to observations in total emission, for the investigation of the structure and of the evolution of protoplanetary disks. The promising prospects of such investigations with ALMA will be discussed
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
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