1,354,783 research outputs found
Mars ionosphere TEC estimation from MARSIS data: A new approach
No full textInternational audienceWe describe a new implementation of the Contrast Method (CM) algorithm (Picardi and Sorge, 2000; Ilyushin Ya and Kunitsyn, 2004; Cartacci et al., 2013) used to correct the phase distortion of the echoes recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) (Picardi et al., 2005; Jordan et al., 2009) in its subsurface mode.The New CM is designed following an improved approach which allows not only to perform its original task but also to estimate the Total Electron Content (TEC) of the Mars ionosphere with a better accuracy respect to the past (Cartacci et al., 2013; Cartacci et al., 2017), in the nightside when the transmitted frequency is close to the ionosphere plasma frequency as well as in the dayside, thanks to a lesser use of theoretical approximations in the method development.Moreover, taking advantage of almost 16 years of MARSIS operations, corresponding to about 8700 orbits, we present an improved global map of the night side TEC variations due to the interaction with the Mars crustal magnetic field (Safaeinili et al., 2007; Cartacci et al., 2013)
Mars ionosphere TEC estimation from MARSIS data: A new approach
No full textWe describe a new implementation of the Contrast Method (CM) algorithm (Picardi and Sorge, 2000; Ilyushin Ya and Kunitsyn, 2004; Cartacci et al., 2013) used to correct the phase distortion of the echoes recorded by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) (Picardi et al., 2005; Jordan et al., 2009) in its subsurface mode. The New CM is designed following an improved approach which allows not only to perform its original task but also to estimate the Total Electron Content (TEC) of the Mars ionosphere with a better accuracy respect to the past (Cartacci et al., 2013; Cartacci et al., 2017), in the nightside when the transmitted frequency is close to the ionosphere plasma frequency as well as in the dayside, thanks to a lesser use of theoretical approximations in the method development. Moreover, taking advantage of almost 16 years of MARSIS operations, corresponding to about 8700 orbits, we present an improved global map of the night side TEC variations due to the interaction with the Mars crustal magnetic field (Safaeinili et al., 2007; Cartacci et al., 2013).</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Surface and subsurface radar backscattering coefficient over the Martian South Polar Layered Deposits from MARSIS data
No full textMARSIS Radar TEC estimation analysis
No full textIn this document, we describe a study to evaluate the possibility to a further improvement of the Total Electron Content of Mars’s Ionosphere using the outputs parameters produced by the Contrast Method algorithm used for the on-board and the on- ground processing of the MARSIS radar, in order to compensate the ionosphere distortions that affected the data collected by MARSIS in its subsurface operation mode
Variations on the Author
No full text“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
No full textWe 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
MARSIS over Elysium Planitia: mapping a subsurface structure in an area with a complex geological history.
No full textDispelling the Myths Behind First-author Citation Counts
No full textWe 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
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
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