1,720,989 research outputs found
Virtues and vices of turbidite bed thickness statistics : data sets from four confined to semi-confined basins of Central-Northern Apennines (Italy) compared and contrasted
No full textThe variability in turbidite bed thickness from a wellbore along with the (unknown) bed shape are important factors in modelling hydrocarbon reservoirs deposited in deep water. Over the last two decades, a number of paper has shown how parameters of statistical distribution of turbidite bed thickness can be useful for discriminating depositional settings, different rheology of parent flows as well as the effect of basin topography on sedimentation. Statistical distributions in the literature are diverse (truncated Gaussian, lognormal, exponential and power law) and variously interpreted as resulting from imprinting of depositional/erosional processes on the input signal (i.e. distribution of parent flow magnitude).
However, other than the long time known ‘thin bed problem’, in outcrop studies there is no assessment of how different data collection methods affect statistics of turbidite bed thickness, which instead is crucial for avoiding misinterpretations. Critical factors include: i) minimum significant number of beds/stratigraphic thickness with reference to type (e.g. channel-levee, depositional lobe etc.) and hierarchy of the investigated turbidite body; ii) single vs. multiple correlative sections; iii) position of the sampling line/area with respect to topographic features (e.g. slope break, bounding slopes in confined situations etc.) of the basin.
Four different data sets from as many turbidite units (namely, the Cengio-Castelnuovo of Tertiary Piedmont Basin and the Marnoso Arenacea, Laga and Cellino Fm. of the Apennine Foreland Basin system) from Central-Northern Apennines (Italy) are compared and contrasted in this study. In agreement with current models in the literature, examples of influence from primary depositional processes and basin confinement on bed thickness statistics are presented and reviewed critically. To do this, we break down the populations of each case study into sub-categories tied to depositional processes (e.g. bed types) and sub-data sets with different degree of flow confinement and location with respect to confining topographic feature. Furthermore, we explore the bias of different data collection procedures on statistical distribution of bed thickness by comparing distributions from single and multiple correlative logs as well as from units of different hierarchical scale and internal architecture. Lastly, we address the universal applicability of any type of statistical distribution to thickness of turbidite beds
How sampling procedures and sedimentary processes of confined basins can modify the observed frequency distribution of turbidite thickness? : examples from Tertiary confined basins of central and northern Apennine (Italy)
No full textThe assessment of turbidite thickness statistics, along with variability of bed geometry, represents an open research question for both applied and pure sedimentology. Empirical frequency distributions of turbidite thickness reported in the scientific literature are diverse (e.g. truncated Gaussian, lognormal, exponential and power law) and variously interpreted as resulting from modification of the input signal (i.e. distribution of parent flow magnitude) by depositional/erosional processes. Yet biases toward or against certain thickness classes due to bed geometry, erosion and data collection are commonly overlooked, casting doubts on thickness statistics as a tool for answering some of the key research questions of turbidite sedimentology. However, in situations where turbidites are confined by basin topography and erosion is negligible, some of the variables of the ‘bed thickness equation’ can be relaxed, making easier to investigate what the primary controls on turbidite thickness statistics are.
This study reviews the bed thickness statistics of four confined to unconfined turbidite units (namely, the Castagnola Fm. and the Cengio-Bric la Croce-Castelnuovo turbidite systems of Tertiary Piedmont Basin and the Laga and Cellino Fms. of the Apennine Foreland Basin System) from the tertiary of Central-Northern Apennines (Italy), where bed geometry and sedimentary character have been previously assessed. Based on comparison of thickness subsets from turbidite systems with different degree of confinement and diverse locations within the basin fill, this contribution aims at answering the following questions: i) how data collection choices and field operational constraints (e.g. location, outcrop quality, use of thickness from single vs. multiple correlative sections, length of the stratigraphic section from which thicknesses were retrieved) can affect statistics of an empirical distribution of turbidite thicknesses so to induce biased interpretations? ii) how depositional controls of confined vs. unconfined basins can modify the initial thicknesses distribution of turbidites?; iii) is there in turbidite thickness statistics a ‘flow confinement’ signature which can be used to distinguish between confined and unconfined depositional settings?
Results indicate that: i) best practices of data collection are crucial to a meaningful interpretation of turbidite thickness data; ii) a systematic bias against cm-thick beds deposited by small volume low density flows exists, which modifies the thin-bedded tail of turbidite thickness distributions and, iii) the thick-bedded tail of thickness distributions of the case studies bears some relationship to the transition from confined and unconfined depositional settings, suggesting its statistics can represent a proxy for the degree of flow confinement
Drilling is not boring : geoarchaeological research at Abu Tbeirah
No full textThis chapter presents the outcomes
of the geo-archaeological research at the ancient
Sumerian site of Abu Tbeirah, spanning from
the third to the early second millennia bc. In
collaboration with Sapienza University of Rome,
the University of Qadisiyah, and Milano University,
this study focuses on of the site’s urban water-
management system, offering insights into
Sumerian hydraulic engineering. Employing
field analysis and satellite imagery, the research
focuses on the natural channels surrounding the
city, artificial canals, and water-related structures
within the Tell. Additionally, the chapter delves
into the site’s environmental context, elucidating
the evolution of the palaeo-channel crossing Abu
Tbeirah and its historical significance. Practical
challenges encountered during fieldwork, and
the solutions devised, are also highlighted. This
research underscores the pivotal role of fluvial
dynamics in shaping the city’s development and
the ramifications of environmental adaptations on the settlement. Notably, the study reveals how the
Sumerians leveraged natural elements such as river
bends and oxbow lakes to engineer sophisticated
water-management systems, facilitating urban
expansion
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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