1,720,955 research outputs found
Giant polygons in the realmonte mine (agrigento, sicily): Evidence for the desiccation of a messemian halite basin
Full text linkThe Messinian Realmonte salt deposit consists of a 400600 m-thick halite succession that can be divided into four main lithologie units (base to top): A) cumulates of plates settled out from a stratified water column; B) plate cumulates in a shallowing-upward sequence containing six kainite layers near the top of the unit; C) cumulates of skeletal hoppers with chevron overgrowths precipitated from a nonstratified water body; and D) skeletal halite and anhydrite. Spectacular vertical fissures cut through the upper part of unit B at its boundary with salt unit C. These fissures are spaced at intervals of up to 5 m apart, extend down to a depth of 6 m, and are filled by red mud. The salt beds affected by the fissures are commonly upturned (buckled) and are truncated and onlapped by the succeeding flat-lying halite beds of unit C. Additionally, the upturned layers are cut by vertical dissolution pipes that extend down to as much as a depth of 4 m below the fissured surface. To explain the observed superimposed structures we propose two mechanisms, both induced by the desiccation of the evaporite basin: (1) When the salt surface was exposed, the halite layers were buckled, broke into polygonal crusts, and formed tepee structures. The budding was caused by a net volume increase due to thermal expansion, and what is more important, precipitation of new halite induced by evaporative pumping of brines moving up from the groundwater table. The buckled salt layers were then affected by meteoric dissolution, which created vertical pipes. (2) The tepee structures and the associated zone of dissolution pipes are further crosscut by a new network of large polygons. These new polygonal sets are outlined by deep fissures in which red silt collected, blown by the wind or carried by episodes of surface flooding. This type of deep contraction crack is known to be produced by volumetric changes induced by annual temperature fluctuations. The documentation of contraction polygons and other exposure features represents the first report of desiccation events during the deposition of the Sicilian salt. No geological data are yet available to settle the questions if the salt of Sicily is correctable with the halite present beneath the floor of the Mediterranean and if the desiccation of the Realmonte salt basin could have been induced by: a) local tectonic causes (uplift of the basin floor by thrust activity, b) simple evaporitic drawdown, c) basinwide drop of the Mediterranean sea level, or d) complex interaction among these factors. Copyright ©1999, SEPM (Society for Sedimentary Geology)
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
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