1,721,109 research outputs found
Evolution in Dust Lane Ellipticals: Detection of Accreted Molecular Gas
No full textThe detection of moderately large quantities of molecular gas in three minor axis dust lane elliptical galaxies is reported. Masses of H2 between 4 × 108 and 2 × 10 Msun have been observed in NGC 1316, NGC 1947, and NGC 5266. The distribution of the molecular gas follows the dust, which is patchy in NGC 1316, around the nucleus in NGC 1947, and in a ring in NGC 5266. The velocities and directions of motion for the CO agree with those of the ionized gas, which rotates perpendicularly to the stars.
Based upon dynamical studies of interacting systems, and following related work on the origin of the H I and ionized gas, we suggest that the H2 comes from gas acquired from an external source, probably through the ingestion of a gas-rich dwarf galaxy. Since dwarfs, though typically rich in H I, are notably poor in H2, some mechanism must exist which converts the atomic into molecular gas. This may be the result of gas compression inside the ring into which the accreted object is smeared.
Following the current theoretical models, the three observed galaxies are situated along a possible evolutionary sequence, with NGC 1316 in the earlier stages of gas (or satellite) accretion and NGC 5266 in a smooth, evolved configuration. The distribution of the molecular gas is entirely consistent with the models
Counter-rotating molecular gas in NGC 4546
No full textThe detection of 9.6 +/- 2.9 x 107 solar mass of molecular gas in the barred S0 galaxy NGC 4546 is reported. This galaxy has an 8 kpc wide disk of ionized gas rotating opposite to the stellar disk (but with approximately the same velocity magnitude). The detected molecular gas has the same motion as the ionized gas (and the atomic gas), counter-rotating with respect to the stars. The molecular gas is concentrated more on the western side of the galaxy, while the atomic gas is apparently more prevalent on the eastern side. The peculiar gas kinematics of NGC 4546 likely come from a past acquisition of gas, probably through a collision with a dwarf galaxy whose relative velocity was retrograde with respect to the galaxy spin. However, the lack of evidence for starburst activity, and the length of time required to form a stable disk structure from an accreted companion, suggest that there is little interaction between the pre-existing and accreted gas at this time
The spreading of SARS-CoV-2: Interage contacts and networks degree distribution
Full text linkNotable cross-country differences exist in the diffusion of the Covid-19 and in its lethality. Contact patterns in populations, and in particular intergenerational contacts, have been argued to be responsible for the most vulnerable, the elderly, getting infected more often and thus driving up mortality in some context, like in the southern European one. This paper asks a simple question: is it between whom contacts occur that matters or is it simply how many contacts people have? Due to the high number of confounding factors, it is extremely difficult to empirically assess the impact of single network features separately. This is why we rely on a simulation exercise in which we counterfactually manipulate single aspects of countries’ age distribution and network structures. We disentangle the contributions of the kind and of the number of contacts while holding constant the age structure. More precisely, we isolate the respective effects of inter-age contact patterns, degree distribution and clustering on the virus propagation across age groups. We use survey data on face-to-face contacts for Great Britain, Italy, and Germany, to reconstruct networks that mirror empirical contact patterns in these three countries. It turns out that the number of social contacts (degree distribution) largely accounts for the higher infection rates of the elderly in the Italian context, while differences in inter-age contacts patterns are only responsible for minor differences. This suggests that policies specifically targeting inter-age contacts would be little effective
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
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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