1,720,968 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
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
Flattened structures of dwarf satellites around early-type galaxies in the MATLAS low density fields
No full textIt was first observed in the 1970s, that the dwarf galaxies orbiting our Milky Way, so-called satellites, appear to be arranged in a thin, vast plane. Similar discoveries were made around different galaxies in the local Universe such as Andromeda, Centaurus A and the M101 group complex. In cases with kinematic data the systems comprised of dwarf galaxies even appear to preferentially co-orbit their massive host galaxy. At this moment, this phenomenon can not be explained to a satisfactory degree by the ΛCDM paradigm. In this work we analyze the spatial distribution of 2210 newly discovered dwarf galaxy candidates around early-type galaxies (ETG) in the MATLAS low density fields. Under the assumption that the dwarf candidates are located at the same distance as the central targeted ETG, we use a combination of visual identification, the total least square (TLS) fitting method and a variation of the Hough transform to determine whether there is evidence of similar flattened structures around the MATLAS ETGs. We find flattened linear structures in 63 out of 120 fields with a statistically relevant number of dwarf candidates through visual inspection. This number is a lower limit since visual identification is only possible if the planes are seen edge-on. We use the TLS method in an attempt to recover the visually detected structures. Simulations with random data attribute statistical significance to 49 of the cases. After removing the fields that suffer from a high degree of stellar halos and/or diffuse cirrus contamination, which potentially impairs dwarf detectability, 33 fields with evidence for such structures remain. We use the Hough method as a second approach to confirm the orientation of the flattened structures that were detected via the TLS method. The TLS method and the Hough method are agreeable in 90% of the cases. We also find that the vast majority of the found dwarf structures reach well outside the estimated virial radii of the ETGs. Of these more extended systems 42% are found to be aligned with the large-scale structure. This work provides a first statistical analysis about the spatial arrangement of an unprecedented number of dwarfs in low density environments. In order to confirm the presence of these more distant planes, distance and kinematic information are needed.Author: Nick HeestersMasterarbeit Universität Innsbruck 202
Anisotropy and Coherence in the Phase-Space Distribution of Dwarf Galaxies - Statistical Tests, Detection Pipeline, and Survey Catalog
Full text linkDwarf galaxies are the most common type of galaxy in the Universe and have emerged as powerful testbeds for our standard cosmological model LambdaCDM on small scales, where several tensions persist. This thesis focuses specifically on the phase-space distribution of dwarf satellites around massive hosts. Several nearby hosts, including the Milky Way, appear to have flattened, kinematically correlated satellite configurations that are uncommon among LambdaCDM analogs---the planes-of-satellites challenge. Robust tests require large, contamination-controlled satellite samples across diverse environments, which are challenging to obtain beyond the Local Group because dwarfs are intrinsically faint and generally have low surface brightness.
This thesis contributes to the extension of phase-space studies beyond the Local Group by (i) evaluating and refining methods to quantify phase-space distributions, in particular lopsided satellite distributions and planes-of-satellites, and conducting statistical tests on such distributions in existing survey data (e.g., MATLAS, ELVES); (ii) expanding line-of-sight velocity coverage via VLT/MUSE spectroscopy of MATLAS candidates and establishing host membership; and (iii) developing an automated pipeline, combining classical methods with deep learning, to build a survey-scale catalog of dwarf galaxy candidates in the wide-field UNIONS survey.
Across 68 host systems in MATLAS/ELVES, ~21% show significant lopsidedness with the signal strongest at larger projected radii, consistent with recent accretions and in line with LambdaCDM expectations. Follow-up on reported candidate planes generally revealed no significant tension with LambdaCDM when revisited with new data. An exception to this trend is the NGC 4490 group, where such a highly correlated structure was identified as uncommon in simulated analogs. In the MUSE program, we confirmed 75% of the MATLAS dwarfs in the sample as satellites; non-members tend to be late-types, supporting morphology as a membership prior. Our pipeline yielded dwarf probability scores for 1.5 million selected objects, producing the Galaxies OBserved as Low-luminosity Identified Nebulae (GOBLIN) catalog. GOBLIN contains ~43,000 high probability (>=0.8) dwarf candidates, which represents a significant increase in the number of high-confidence candidates in the local Universe.
Taken together, the majority of our investigations into phase-space distributions of dwarfs revealed consistency with LambdaCDM given current data. There are, however, noteworthy exceptions, and several systems are still far from complete in terms of distance and velocity estimates. Such measurements are necessary to draw definitive conclusions. Our publicly available GOBLIN catalog contains a large sample of high-probability dwarf candidates, laying the foundation for targeted follow-up campaigns and future phase-space studies.LASTR
Flattened structures of dwarf satellites around early-type galaxies in the MATLAS low density fields
No full textIt was first observed in the 1970s, that the dwarf galaxies orbiting our Milky Way, so-called satellites, appear to be arranged in a thin, vast plane. Similar discoveries were made around different galaxies in the local Universe such as Andromeda, Centaurus A and the M101 group complex. In cases with kinematic data the systems comprised of dwarf galaxies even appear to preferentially co-orbit their massive host galaxy. At this moment, this phenomenon can not be explained to a satisfactory degree by the ΛCDM paradigm. In this work we analyze the spatial distribution of 2210 newly discovered dwarf galaxy candidates around early-type galaxies (ETG) in the MATLAS low density fields. Under the assumption that the dwarf candidates are located at the same distance as the central targeted ETG, we use a combination of visual identification, the total least square (TLS) fitting method and a variation of the Hough transform to determine whether there is evidence of similar flattened structures around the MATLAS ETGs. We find flattened linear structures in 63 out of 120 fields with a statistically relevant number of dwarf candidates through visual inspection. This number is a lower limit since visual identification is only possible if the planes are seen edge-on. We use the TLS method in an attempt to recover the visually detected structures. Simulations with random data attribute statistical significance to 49 of the cases. After removing the fields that suffer from a high degree of stellar halos and/or diffuse cirrus contamination, which potentially impairs dwarf detectability, 33 fields with evidence for such structures remain. We use the Hough method as a second approach to confirm the orientation of the flattened structures that were detected via the TLS method. The TLS method and the Hough method are agreeable in 90% of the cases. We also find that the vast majority of the found dwarf structures reach well outside the estimated virial radii of the ETGs. Of these more extended systems 42% are found to be aligned with the large-scale structure. This work provides a first statistical analysis about the spatial arrangement of an unprecedented number of dwarfs in low density environments. In order to confirm the presence of these more distant planes, distance and kinematic information are needed.Author: Nick HeestersMasterarbeit Universität Innsbruck 202
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
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