1,720,957 research outputs found
The value of pocket penetration tests for the high-resolution palaeosol stratigraphy of late Quaternary deposits
No full textPocket penetrometer measurements, though commonly listed as accessory components of core descriptions, are almost totally ignored in shallow subsurface stratigraphic analysis. In this study, we prove that, if properly calibrated with core data, pocket penetration tests may serve as a quick and inexpensive tool to enhance high-resolution (palaeosol-based) stratigraphy of unconsolidated, late Quaternary non-marine deposits. A palaeosol sequence, made up of 12 vertically stacked, weakly developed palaeosols (Inceptisols) dated to the last 40ky cal BP, is reconstructed from the subsurface of the southern Po Plain. The individual palaeosols exhibit flat to slightly undulating geometries and several of them can be tracked over distances of tens of km. They show substantially higher compressive strength coefficients than all other fine-grained, alluvial (floodplain) facies, being typified by distinctive penetration resistance, in the range of 3.5-5kg/cm2. Along the palaeosol profiles, A and Bk horizons demonstrate consistent difference in relative compressive strengths, the highest values being almost invariably observed at the A/Bk boundary. Palaeosols are rarely described in conventional stratigraphic logs, and just a small proportion of them is likely to be identified by geologists with no specific sedimentological training. Through core-log calibration techniques, we document that vertical profiles of penetration resistance measured in the field can be used as an efficient method for palaeosol identification, and thus may represent a strategy for predicting stratigraphic architecture from limited core descriptions or poor-quality field logs. This technique allows to optimize the contribution of all available stratigraphic information, expanding significantly the coverage of well-described, one-dimensional core data
Paleosols and associated channel-belt sand bodies from a continuously subsiding late quaternary system (Po basin, Italy): New insights into continental sequence stratigraphy
Full text linkPrevious sequence-stratigraphic work has emphasized the key role of paleosols and associated sand-dominated fluvial bodies as key features for interpreting alluvial architecture. The temporal resolution of the ancient record is, however, insufficient to fully explain the complex relationship between soil formation and the evolution of fluvial systems under changing sea-level and climate conditions. In this paper, we present a detailed record of paleosol-channel belt relationships reconstructed from the subsurface of a rapidly subsiding region (Po Plain, Italy) that spans almost all of the last glacial-interglacial cycle (~120 k.y.). The studied succession preserves a systematic bipartite zonation into a thick paleosol-bearing segment close to the basin margin and a sand-dominated interval, with vertically amalgamated channel belts, in an axial position. Individual paleosols are weakly developed and represent key stratigraphic markers that can be traced basinwide into adjacent, essentially contemporaneous, unconfined channel-belt deposits. Unlike conventional models of late Quaternary alluvial-coastal plain systems, no persistent incised valley was established in the Po system during the last glacial-interglacial cycle. Continuous accommodation was the key depositional control on alluvial stratigraphy during the prolonged (~90 k.y.) phase of late Pleistocene sea-level fall, which led to the deposition of a thick, dominantly aggradational alluvial succession. The development of shallowly incised, short-lived valley systems took place only at the transition to glacial stages associated with substantial sea-level drop (marine oxygen isotope stage [MIS] 3-2 transition, and possibly MIS 5-4 transition). This study shows that in rapidly subsiding settings with high rates of sedimentation, incised valley systems may be replaced by aggradationally stacked, essentially non-incised fluvial bodies. In these cases, overbank packages bounded by immature paleosols represent the most likely alternative to the highly weathered interfluve paleosol predicted by classic sequence-stratigraphic models. Fourth-order sequence boundaries and lower-rank erosional surfaces may be easily confused at the ~100 k.y. scale, and transgressive surfaces, defining the onset of retrogradation, may become the most readily identifiable sequence-stratigraphic surfaces
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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