1,721,013 research outputs found
Isotopic composition of lead for raw material tracing: the case of Roman lead-glazed ceramic
No full textNumerous studies of glazed coatings on ancient ceramics aimed at understanding the ancient production process,
how it changed and developed through the centuries (Tite et al., 1998; Özçatal et al., 2014). In addition, investigating
the provenance of the raw materials involved in glaze production is important to reconstruct the main trade routes that
disseminated this technology.
Stable lead isotope analyses, using secondary ion mass spectrometry (SIMS), was applied to trace the provenance of
lead minerals involved in the production of Roman lead-glazed ceramics. The fragments analyzed here were unearthed
in different archaeological contexts of ancient Rome (Testaccio Market, Magna Mater sanctuary and Domus Tiberiana
on the Palatine Hill, Forum of Caesar and Forum of Nerva), spanning the period from the 2nd Century AD to the Middle
Age.
The ceramics analyzed clustered within the distribution patterns of several deposits including Bulgaria, Italy
(Sardinia), Greece and Britain. However, the comparison with the lead isotope data of ores by statistical treatment of the
data (PCA) shows that the deposits from England were important sources of lead used for the production of glazed
ceramics since the second Century AD.
A comparison of our lead isotopic results obtained using SIMS with data collected from previous works by ICP-MS
and TIMS (Wolf et al., 2003; Walton & Tite, 2010) shows that SIMS can be used for lead isotope provenance research.
In addition, SIMS micro-analytical technique includes easy sample preparation, quick acquisition times, and is
minimally destructive, which are advantages in the field of cultural heritage (Hull et al., 2014). Furthermore, the
acquisition of accurate and precise isotopic measurements on a micrometer scale with the possibility to choose the
location of each analysis point avoids the inclusions especially in the case of ceramic material
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
The mineralogy, geochemistry, and geochronology of the Triple R uranium deposit, Patterson Lake Property, Athabasca Basin, Canada
No full textThe Athabasca Basin, Saskatchewan, Canada is one of the richest uranium (U) provinces in the world and hosts the highest-grade deposits. Most of the best studied deposits are located in the eastern part of the basin, whereas the U deposits in the western Athabasca Basin are relatively understudied. Mineral textures and relationships between alteration, and stable and radiogenic isotopic ratios from dravite, quartz, pyrite, galena, and uraninite were used to develop a genetic model for the unconformity-related. Triple R U deposit, located in the western Athabasca Basin. The Triple R U deposit is located in the basement rocks immediately south of the southwestern margin of the Athabasca Basin, where the overlying sedimentary rocks have been eroded. The basement is ~1.9 Ga and composed of quartz-feldspar-garnet-biotite gneisses and intermediate to mafic orthogneisses where U mineralization is associated with NE- to SW trending structural zone. These host rocks contain abundant amounts of carbonaceous material and are strongly argillized, silicified, chloritized, hematized, and locally desilicified. Uranium mineralization occurs in zones as massive, botryoidal, fracture-hosted, and disseminated patches of uraninite with varying amounts of late stage coffinite and uranophane. The minimum age for the Triple R deposit is ~ 1450 Ma was obtained using U-Pb geochronology. An array of younger ages correlated with depth; from deposit to most shallow they are ~ 1250 Ma, ~ 1000 Ma, ~ 650 Ma, and ~ 400 Ma. These ages are the result of resetting of the U-Pb system by subsequent fluid events that can be correlated with several tectonic events. The main mineralizing stage formed from basinal (marine) source fluids with a temperature of ~200°C, based on the hydrogen and oxygen stable isotopic composition from various co-existing dravite-quartz-illite associations. The boron isotopic composition of tourmaline minerals suggested that the source of the boron was seawater or marine evaporates. A late generation of illite (Ill3) formed from ~50°C meteoric fluids at 450 Ma.October 202
Fluid events associated with gold, uranium, and REE deposits in the proterozoic of northern Saskatchewan, Canada
No full textThe Contact Lake lode gold deposit is situated in northern Saskatchewan within the Proterozoic La Ronge Domain of the Trans-Hudson Orogen (1.9-1.7 Ga). The deposit is associated with a high angle, reverse shear zone, which crosscuts the central granitic and granodioritic phases of the composite Little Deer Lake pluton. Four temporally distinct stages of veining within the shear zone have been identified on the basis of mineralogical, textural and crosscutting relationships. The four discernable vein types (two devoid of gold and two containing gold mineralization) permit the detailed study of fluids responsible for gold mineralization versus barren fluids, which is critical to gold exploration. High grade gold mineralization is related to stage IV veins. The interaction between the auriferous stage IV vein fluid and the granitic and granodioritic phases of the pluton produced distinct alteration mineral assemblages. The Proterozoic Athabasca Basin in northern Saskatchewan, Canada, hosts several of the largest and richest uranium deposits in the world. The uranium deposits occur at the intersection between Hudsonian-age faults and the unconformity between Athabasca Group sandstones and Aphebian metasediments and Archean gneisses. Uranium mineralization formed at ca. 200°C from the mixing between the oxidizing, uranium bearing basinal brine and the reducing basement fluid which issued along the faults. High concentrations of REE-rich phosphates are associated with uranium mineralization in the Athabasca Basin. The relations among REE-rich minerals, diagenetic clays and uranium mineralization in the basin and basement rocks indicate extensive REE mobility during diagenesis of the Athabasca Basin. The REEs and U most likely were derived from detrital fluor-apatite and zircon in the sandstone, and garnets in the basement rocks. These relations indicate that REEs, and possibly the uranium, were transported as F-complexes. The three stages of ore formation and associated alteration minerals permit the detailed study of fluids responsible for uranium deposition and alteration, which is critical to understanding and refining the model for the genesis of unconformity-type uranium deposits. In addition, the high concentration of REEs associated with uranium mineralization may render these deposits viable sources of REEs in addition to uranium. (Abstract shortened by UMI.
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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