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Per la tipologia dei portali nell’architettura romanica in Sardegna: La chiesa di San Leonardo di Siete Fuentes
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Architectures of planetary systems with giant companions in outer orbits
No full textIn the last 30 years, exoplanetary science went from being a field of pure speculation to one of the most intriguing and popular ones of all astrophysics. An unprecedented effort has been put in to expand our understanding of how exoplanets form and evolve, and a lot of questions have been answered while many others remain. Ultimately, our greatest goal consists of finding a planetary system like our own with an Earth twin planet. Whether we are alone or not in the universe is a question that everyone has asked themselves at least once and the purpose of planetary science, together with astrobiology, is to answer it. However, the task is far from trivial due to a combination of factors: no a priori knowledge of whether such a planet exists, technological limits, physical processes that complicate our search (e.g., stellar activity), and so on. However, after three decades of hard work, we are now able to get at least a general idea about what we can expect to find in the countless planetary systems that very likely exist in our galaxy alone. In particular, a good starting point is the discovery of Jupiter-like planets that should create a stable environment where their inner and smaller siblings are allowed to thrive and, maybe, to host life.
In this thesis, I am going to present a long work that has accompanied me for the last three years. In the first part, I analyzed four planetary systems exploiting previously unpublished data gathered with HARPS-N in the framework of the GAPS project. These have been combined with literature RV data, Gaia-Hipparcos astrometry, and direct imaging to obtain very accurate results for long-period planets, a part of the parameter space so far not fully explored. We constrained the orbits of a new substellar companion for each of the cases considered, all of them having large masses (up to the brown dwarf domain) and periods ≳ 13 yr. In the second part, we selected a large and uniform sample of stars hosting Jupiter-like planets, analyzed all the available RV data for them, and then combined the results to perform a statistical analysis to determine the occurrence rates of small close-in planets. This provided us with a lot of interesting and useful information regarding whether Solar System analogs exist and their architectures. We found that indeed small planets should be common in the inner regions of systems hosting external gas giants, provided that these do not disturb said regions gravitationally. Our results are consistent with previous literature works and shed further light on the age-old question of the existence of worlds similar to ours
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
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