1,720,957 research outputs found
Intense dynamic optical auroral sub-structure as a proxy for ionospheric density irregularities
No full textWhen signals from Global Navigation Satellite System (GNSS) propagate through the ionosphere, disruption to the phase and amplitude of the signals can occur due to the presence of plasma density irregularities. Several phenomena have previously been associated with the formation of ionospheric irregularities, auroral precipitation being one of them; however, the nature of this relationship is still uncertain. In this study we use a suite of instruments to investigate the relationship between scintillation and an intense, discrete, dynamic auroral display on 11th January 2016. We find a temporal correlation between auroral brightness and scintillation, consistently at and around zero lag. Moreover, our analysis suggests the E-region to be the dominant source of irregularities causing scintillation in this event. Using high-resolution, narrow field-of-view observations from the Auroral Structure and Kinetics (ASK) instrument and a novel algorithm for determining scale-dependent power in the aurora, we find evidence for a possible relationship between optical structure sizes and scintillation. The results from our analysis provide further insight into the relationship between the aurora and GNSS scintillation, and suggest a worthwhile direction for further research
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
On the Dependence of Amplitude and Phase Scintillation Indices on Magnetic Field Aligned Angle:A Statistical Investigation at High Latitudes
No full textThis letter presents for the first time the results of a statistical study that had looked into the dependence of scintillation on the propagation geometry of GPS signals at high latitudes by combining the geometrical parameters, namely elevation and azimuth, along with the magnetic field vector into a single variable called the magnetic field aligned angle (MFAA). An increase in the value of scintillation indices when MFAA approaches zero is observed. This indicates the presence of field-aligned irregularities and the fact that MFAA is sensitive to irregularities whose size extends to Fresnel scales as well. Contrary to previous experimental and modeling studies which have shown higher variations of σφ index as compared to the S4 index with the propagation geometry of GPS signals, our results suggest that these higher fluctuations in σφ were refractive in origin and were the result of improper detrending of the phase at high latitudes where the use of constant cutoff of 0.1 Hz is not accurate due to higher ionospheric plasma drift velocities at these latitudes
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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