1,720,963 research outputs found
Microscopic quantal calculation of the vortex-nucleus interaction in the inner crust of neutron stars
No full textIn this article we study the interaction between vortices and nuclei present in the
inner crust of neutron stars, performing microscopic calculations based on quantum mean
field theory. We find that the properties of the vortex are strongly influenced by finite
size effects, leading to qualitative differences respect to results based on semiclassical
approximations
On the structure of vortices in the inner crust of neutron stars
No full textWe study the structure of vortices and their interaction with nuclei in the inner crust of neutron stars. Vortices carry most of the angular momentum of the crust and according to some models are expected to play a key role in the phenomenon of glitches. The quantities of interest (the energy, the pairing gap, the density and the velocity field) are calculated in the framework of the Hartree-Fock-Bogoliubov (HFB) quantum mean field theory. We solve the HFB equations testing four different Skyrme functionals in the particle hole-channel and using a density-dependent contact interaction in the particle-particle channel. We find that the structure of a vortex is strongly affected by the presence of the nucleus, a fact which reflects itself in the density dependence of the pinning energy we calculate
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
Hartree Fock Bogoliubov calculation of the pinning energy of vortices on nuclei in the inner crust of neutron stars
No full textVortex–nucleus interaction in the inner crust of neutron stars
No full textThe structure of a vortex in the inner crust of neutron stars is calculated up to density equal to one fourth
of the nuclear saturation density, within the framework of quantum mean field theory, taking into account
the interaction with the nuclei composing the Coulomb lattice. Vortices are associated with Coopers pairs
formed out of single-particle levels of opposite parity and, due to (quantal-size) shell effects, their formation
is hindered within the nuclear volume, by an amount that depends on the Fermi energy and on the effective
mass associated with the adopted nuclear two-body interaction. When the vortex axis goes through the
center of a nucleus, the typical linear rise of the pairing gap away from the vortex axis is delayed by about
8 fm, as compared to the case of a vortex in uniform matter. Also the velocity field is suppressed in a large
region close to the interface between the nucleus and the neutron gas. As a consequence, pinning of a vortex
on a nucleus leads to a loss of condensation energy, contrary to the predictions of all previous models. This
result strongly influences the density dependence of the pinning energy, relevant in the study of glitches.
We find that pinning of vortices on nuclei is favoured at low density
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
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