1,721,070 research outputs found
Evidence of a sub-solar star in a microlensing event toward the LMC
Full text linkGravitational microlensing is known to be an impressive tool for searching dark, small, and compact objects that are missed by the usual astronomical observations. In this paper, by analysing multiple images acquired by DECam, we present the detection and a complete description of the microlensing event LMC J05074558-65574990 which is most likely due to a sub-solar object with mass (0.16±0.10) M⊙, hence in the mass range between a massive brown dwarf and a red dwarf, whose distance is estimated to be 7.8−3.4+4.1×102 pc thanks to the Gaia observation of the source, leading us to consider this lens as one the closest ever detected
System of selfgravitating semidegenerate fermions with a cutoff of energy and angular momentum in their distribution function
No full textWe study the gravitational equilibrium of static, spherically symmetric, Newtonian systems consisting of a collisionless semidegenerate Fermi gas. A cutoff in the phase space distribution function of the particles is introduced in order to avoid the problems arising from the infinite radius of semidegenerate configurations when the usual Fermi-Dirac function is used. We consider, here, the more general case of a cutoff in energy and angular momentum, the latter giving an anisotropy in the velocity space. The treatment is applied to model massive galactic halos. Limits on the mass of the "inos" composing the halos are derived both from phase space constraints and from general features of the observed rotation curves in spiral galaxies
Near-infrared photometry of LSI +61 303
No full textThe results of long-term monitoring of the peculiar object LSI +61 deg 303 at IR wavelengths are presented. The behavior of a Be star with a near-infrared excess is observed. Significant flux variations are seen, but no correlation with the 26.5-day radio period is found. On the other hand, the spectral variations observed during the source high state are suggestive of a long-term star activity...
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
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