1,720,972 research outputs found
Geochemistry of carbonate rocks and ferruginous horizons in the verrucano in southern Tuscany - paleoenvironmental and paleogeographic implications
No full textMineralogy and chemistry of carbonate rocks and of ferruginous shales and ironstones contained in the Permo(?)-Triassic continental sedimentary sequence from southern Tuscany (Italy) support detailed paleoenvironmental and paleoclimatic reconstructions. The composition of carbonate rocks rich in Mn and Ba and low in Sr is consistent with a marine tidal depositional environment of lagoonal type where high-Mg calcite deposition predominates and mildly evaporitic conditions favoured the formation of anorganic micritic limestones, sometimes containing minor amounts of evaporitic elements (Ba). The low Sr levels suggest post-depositional diagenetic processes in which fresh water acts as diagenizing solution. The ferruginous shales and ironstones seem to be related to the development of paleosoils under tropical weathering regimes favouring the selective mobilization of more soluble elements (Na, Ca) and of iron which reprecipitates near the soil surfaces according to the formation mechanism of the ironstone caps ("cuirasses ferrugineuses") in present tropical areas. A paleogeographic reconstruction of the Early- Middle Triassic environment of southern Tuscany is presented. The Verrucano sedimentary sequence was deposited in continental basins (graben) developed during a distensive phase after the Hercynian orogeny not far from the coast, under semi-arid conditions. The continental sedimentation was interrupted by limited marine ingressions during which coastal lagoons were established that were suitable for limited carbonate sedimentation
Sedimentology, Petrografy and Provenance of the triassic Verrucano Group, Monte Argentario (Tuscany Italy)
No full textDeposition of the Verrucano Group (max. thickness 700 m) took place in a series of N-Strending grabens after rifting of the Hercynian basement. The presence of violet-gray mudrocks, caliche nodules and crusts, and the abundance of iron oxides in the sandstones and siltstones suggest that the Verrucano was deposited when the climate was semiarid.The scarcity of conglomerates and presence of upward-fining cycles suggest that the upper part was deposited by low-sinuosity mcandcring streams. T'he abundance ofconglomerate andabsenceo f sequencest ypic:rl of point bars indicate that the rest of the Verrucano was deposited chiefly by high-gradient braidcd streams. Low-grade metamorphism, which occurred duringthe Alpine orogcny, resulted in the recrystallization of argillaceous rock fragments and clay rip-up clasts, but did not clestroy primary sedimentary structures or recrystallize detrital quartz. Based on modal analyses, the sandstone composition in percents is quartz, ; microcrystalline quartz in rock fragments, quartz-mica rock fragments, mica rock fragments, iron oxides, Feldspars:The conglomerates are composed chiefly of quartz, showing various degrees of strain,and metachert .metasandstones, micas chist
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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