1,721,044 research outputs found
Space weathering on minor bodies induced by ion irradiation: some experimental results", Mem. S.A.It. Suppl. 6, 45-50 (2005).
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Space weathering and the color–color diagram of Plutinos and Jupiter Trojans
Full text linkThe Jupiter Trojan asteroids and the Plutinos are two peculiar populations. They are dynamically resonant, therefore with heliocentric distances relatively bounded for long timescales, as a farely general rule. As a consequence, some correlation with the surface color properties of their respective members is expected. Indeed, there are apparent differences in the B-V vs. V-R color–color diagram of the two populations. Using a simple model based on the surface color due to the contribution of two components, one pristine and one altered, we find as plausible that the difference is due to the interplay of space weathering by energetic cosmic-radiation and collisional effects.Fil: Melita, Mario Daniel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Kanuchová, Z.. Astronomical Institute of Slovak Academy of Sciences; EslovaquiaFil: Brunetto, R.. Centre National de la Recherche Scientifique; FranciaFil: Strazzulla, G.. Osservatorio Astrofisico di Catania; Itali
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
Collisions, Cosmic Radiation and the Colors of the Trojan Asteroids
Full text linkThe Trojan asteroids orbit about the Lagrangian points of Jupiter and the
residence times about their present location are very long for most of them.
If these bodies originated in the outer Solar System, they should be mainly
composed of water ice, but, in contrast with comets, all the volatiles close to the
surface would have been lost long ago. Irrespective of the rotation period, and
hence the surface temperature and ice sublimation rate, a dust layer exists always
on the surface. We show that the timescale for resurfacing the entire surface of
the Trojan asteroids is similar to that of the flattening of the red spectrum of
the new dust by solar-proton irradiation. This, if the cut-off radius of the size
distribution of the impacting objects is between 1mm and 1m and its slope is -3,
for the entire size-range. Therefore, the surfaces of most Trojan asteroids should
be composed mainly of unirradiated dustFil: Melita, Mario Daniel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Strazzulla, G.. Osservatorio Astrofisico di Catania; ItaliaFil: Bar Nun, A.. Tel Aviv University; Israe
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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