1,721,013 research outputs found
New data and insights on the secondary glass workshop of Comacchio (Italy): MgO contents, steatite crucibles and alternatives to recycling
Full text linkThis study introduces a collection of 33 glass samples, encompassing production indicators (blocks, fluidity tests, drops, cuts and wastes) and finished products (mainly goblets and probably a lamp) dating to the second half of the 7th century, except for a single more recent specimen (12th-14th). Additionally, a fragment was taken from a crucible bearing a thin layer of glass inside it. This new collection complements the investigation of glass materials from the Comacchio workshop previously analysed by Bertini et al. (2020).Measurements were performed using scanning electron microscopy, electron microprobe, laser ablation inductively coupled plasma mass spectroscopy on all samples and Sr-Nd isotopic analyses on 5 blocks.The results showed how the entire collection can be classified as natron-based silica-soda-lime glass and that the high MgO contents frequently observed are due to contamination with the steatite crucible. Contextually, the hypothesis of using plant ash-based glass mixed with natron-based glass formulated in the previous literature seems to have run out, along with the use of plant ash-based glass itself, further weakened by the very low representativeness of this latter type of glass on the site.The technological investigation further elucidated that recycling may not singularly account for the Comacchio glass technology. Discernible correlations may suggest the introduction of different types of metals, indicating a specialised control over the production process. Notably, the preference for green-blue glass emerges as a distinctive hallmark, underscoring the deliberate pursuit of a specific aesthetic taste.Lastly, the provenance analysis showed that over three-quarters of production was based on semi-finished products from Egypt, while only the remaining quarter came from the Levantine coast
The glass assemblage from San Pietro in Castello: tracing glass technology and innovations in the Venetian lagoon
Full text linkThis study presents the results of a comprehensive archaeometric investigation of a glass assemblage from the early medieval levels of San Pietro in Castello (Olivolo, Venice), a site of strategic importance during the formative stages of the city. A total of 45 samples, including finished vessels, architectural glass, production waste and a crucible, were analysed using SEM-EDS, EMPA, and LA-ICP-MS. As for glassmaking technology, the results reveal various colouring and opacification strategies, including the use of metallurgical by-products such as cobalt-bearing slag and the co-occurrence of calcium antimonates and lead stannates for the realization of decorative threads. Furthermore, the analysis of the steatite crucible and adhering glass provides insight into contamination processes and their implications for provenance studies. As for glass provenance, the chemical composition shows a near-equal distribution of Levantine and Egyptian natron glass, though differently distributed from a chronological standpoint (Levantine only in later phases). Of particular interest is also the finding of two plant-ash based glass samples, with the earliest one dating to the 8th century and attributed to Syro-Levantine production. Overall, the findings highlight Venice’s early involvement in the technological transition from natron- to plant ash-based glass and suggest that the San Pietro in Castello site may have played a pivotal role in the distribution and reworking of imported raw materials
New <sup>40</sup>Ar-<sup>39</sup>Ar dating and revision of the geochronology of the Monte Amiata Volcano, Central Italy
No full textThe duration of the Mt. Amiata volcanic activity is still a matter of debate, in spite of the presence of several geochronological data in the literature. We performed new 40Ar-39Ar dating on the sanidinegroundmass pairs of the upper stratigraphic units: Dome and massive Lava flows Complex (DLC) and Olivine Latitic final Lavas (OLF). The aim was twofold: to check the reliability of sanidine ages as geochronometer in these products, questioned in the literature, and to better define the chronology of the late activity of this volcano. Ages obtained on coexisting sanidine and groundmass of the Dome and massive Lava flows Complex (DLC) samples overlap within errors, demonstrating that sanidine crystals recorded reliable emplacement ages in these rocks. The Olivine Latite final lavas (OLF) display a different scenario, where the groundmass has an age younger than that of the sanidine, which is xenocrystic and, evidently, retains inherited Ar. Preferred ages for analysed DLC samples are comprised between 301 and 294 ka, an interval of time too short to resolve the ages of the four dome samples taken into account. The Ermeta lava is about 60 ka younger. We propose that the majority of Mt. Amiata volcanic rocks were emplaced in a narrow interval of time, whilst a temporal gap, which needs more detailed constraints, exists with at least one of the Olivine Latite final lavas (OLF)
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
Conservation of 87Sr/86Sr isotopic ratios during the winemaking processes of 'Red' wines to validate their use as geographic tracer
Full text link87Sr/86Sr has been determined in wines, musts grape juices, soils and rocks from six selected vineyards of 'Cesanese' wine area. Cesanese is a monocultivar wine from a small region characterised by different geologic substrata, a key locality to test the influence of both substratum and winemaking procedure on the 87Sr/86Sr of wines. Experimental work has been performed on wines from different vintage years to check possible seasonal variations. The data reveal that 87Sr/86Sr does not change through time, to validate the selection of wineries performed, and in addition no isotopic variations are observed during winemaking. Indeed, no significant isotopic variations have been observed in musts and wines. These findings reinforce the hypothesis that the isotopic signature of wines is strongly related to the bioavailable fraction of the soil rather than to its bulk. The data corroborate the possibility that Sr-isotopes of high-quality wines can be used as a reliable tool for fingerprinting wine geographic provenance
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
Cold subduction zone in northern Calabria (Italy) revealed by lawsonite–clinopyroxene blueschists
No full textLawsonite blueschists are important markers of cold subduction zones, subjected to intense fluid circulation. This is because lawsonite preservation in exhumed blues- chists and eclogites is typically linked to cold exhumation paths, accompanied by hy- dration. In the Catena Costiera (Calabria, southern Italy), lawsonite–clinopyroxene blueschists of the Diamante–Terranova Unit, affected by ductile shearing and retro- gression, are exposed. Blueschists contain zoned clinopyroxene crystals, showing core–rim compositional variation from diopside to omphacite and hosting primary inclusions of lawsonite and titanite. Thermodynamic modelling of phase equilibria in the NCKFMASHTO system revealed peak metamorphic conditions of 2.0–2.1 GPa and 475–490°C for the Alpine subduction in Calabria. The subsequent post-peak metamorphic evolution mainly proceeded along a decompression and cooling path up to ~1.1 GPa and ~380°C. The final exhumation stages are recorded in the sheared blueschists where a mylonitic to ultramylonitic foliation developed at ~0.7 GPa and 290–315°C. Therefore, the P–T evolution of the Diamante–Terranova blueschists mostly occurred in the stability field of lawsonite, sustained by H2O-saturated condi- tions during the exhumation path. The results of this study indicate that the blueschists underwent peak metamorphic conditions higher than previously thought, reaching a maximum depth of ~70 km under a very cold geothermal gradient (~6.6°C/km), dur- ing the Eocene subduction of the Ligurian Tethys oceanic crust in Calabria
Conservation of 87Sr/86Sr During Wine-Making of White Wines: A Geochemical Fingerprint of Geographical Provenance and Quality Production
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