1,720,967 research outputs found
Pleistocene lacustrine fan delta deposits of the Valdarno Basin
No full textAaSTRACr: During the Early Pleistocene, mouth bar fan deltas formed on the northern margin of the shallow water lacustrine Valdarno Basin, which developed during the last phases of the Northern Apennines evolution. One fan delta, studied in detail here, is a coarse-grained, fluvial-dominated system and shows characteristics different from the classic Gilbert-type model. The apex is morphologically and sedimentologically similar to those reported for alluvial fans of humid climates. Very course-grained, poorly organized deposits, dumped as lobes during intense floods or laid down in braided channels, predominate. Downfan, in the transition zone, braided channels change into stable straight channels lacking evidence of lateral accretion. These consist of lenticular pebbly sand and sandy bodies included within massive mud and fine sand. In the subaqueons zone the straight distributary channels, cut into muddy lacustrine deposits, are filled with sand. Distally, such channels give way to l..
Arid climate 2.5 Ma in the Plio-Pleistocene Valdarno Basin (Northern Apennines, Italy)
No full textDistinctive, eolian-dominated sandy deposits 35 m thick exposed in the SW margin of the Plio-Pleistocene Valdarno Basin in the Northern Apennines, Italy, reflect an unusually arid period in the region. Paleomagnetic investigation and 40Ar/39Ar dating of a tephra layer, 10 m above the eolian sand, suggest that the sand was deposited between about 2.7 to 2.4 Ma. This age is comparable to the global climatic deterioration that occurred at the Middle-Upper Pliocene transition. Eolian sediments are represented by cross-bedded sand, rippled sand and horizontal-bedded sand. The alluvial deposits, associated with the eolian sediment, consist of sheet-like beds of coarse sand and erosively based pebbly sand bodies. Eolian sand, together with fluvial sandy deposits, were formed in the medial-distal portion of an alluvial system, and represent the Rena Bianca Sand Unit. The eolian and alluvial deposits are arranged into sedimentary cycles (2-6 m thick), displaying wetting-drying-wetting upward trend recording second-order climatic oscillations of ca 40 ka. Each cycle is included between major bounding surfaces, defined by iron mineral encrustations. These bounding surfaces represent periods of reduced eolian sand accumulation caused by a rising water table. During the 2.5 Ma global cooling the Valdarno Basin experienced a period of arid conditions owing to the influence of cold and dry eastern and northeaster trade wind. In contrast, during the Pleistocene, the uplift of the Pratomagno Ridge protected the Valdarno Basin from eastern and north-eastern trade winds, giving rise to relatively warm and wet conditions, and mitigating the regional and global climatic changes
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
Geomorphic and hydroclimatic control on recent channel avulsion in a small catchment of the Ethiopian plateau
No full textThe presentation describes the recent (Holocene) evolutions of the Awash River in the Lakes Region of the main Ethiopian Rift Valley. The drianage network of the area is analysed and put into relation with the structural setting of the area. The evolution of teh relationship between the main rivers entering Ziway lake, the size od their delta and the drainage and pattern changes that occurred in the Awash and its main tributaries (maily the Meki River) are descibed
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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