1,720,973 research outputs found
Geological mapping of the Daedalia Planum lava field through morphological and spectral analysis
No full textOxygen isotopic composition of fulgurites from the Egyptian Sahara and other locations
No full textRATIONALE: Fulgurites are glassy crusts or hollow glassy tubes formed by the impact of a lightning strike on a target
material on the Earth’s surface. The oxygen isotopic composition of fulgurites has never been measured and, consequently,
it is unknown whether or not isotopic fractionations take place between the target material and the fulgurite glass during
the lightning event which is an excellent natural example of extremely fast melting process.
METHODS: Followingwell-established procedures (high-temperature reaction of the fulguritematerial with BrF5, conversion
into CO2 of the evolved O2 and measurement of the18O/16O ratio on a Finnigan Delta Smass spectrometer) wemeasured for
the first time the oxygen isotopic composition of sets of fulgurites coming from various locations on the Earth’s surface.
RESULTS: The range of isotopic values is quite large, probably reflecting the oxygen isotopic values of the target materials.
In the case of fulgurites from the Sahara Desert the isotopic values obtained from the bulk material, quartz crystals sticking
to the fulgurite body, tiny samples of loose sand coming from fulgurite bubbles, and sand samples collected near the
fulgurites, are very close to one another.
CONCLUSIONS: Although we do not have indisputable evidence, we conclude that, at least in the case of oxygen, the
fusion process of the material struck by lightning, as well as all the extremely fast high-temperature fusion processes,
probably take place without any isotopic fractionation effect
Spectral analysis and geological mapping of the Daedalia Planum lava field (Mars) using OMEGA data
No full textThe great variety of morphologies observed in the Daedalia Planum lava flows (Mars) encouraged a detailed study of their spectral characteristics, in order to obtain information about lava composition and detect possible differences in the spectra of the flows. The OMEGA spectral data collected from the lava field appear rather similar, with absorptions between 0.8 and 1.4 μm and 1.8 and 2.5 μm, suggesting the presence of mafic minerals, which are typical primary mineral phases of volcanic rocks. Moreover, after the subtraction of the background absorption (continuum removal), we highlighted the presence of two classes of spectra both compatible with tholeiitic basalts but with different proportions of Ca in the pyroxene. Despite the similar absorption bands, Daedalia spectra show differences in albedo and spectral slope. By employing the average spectra of the different flow units as end-members, a SAM (Spectral Angle Mapper) classification was performed. The resulting spectral map reveals a relationship between spectral behavior and flow surface textures
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
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
- …
