1,720,957 research outputs found
Underground salt weathering of heritage stone: lithological and environmental constraints on the formation of sulfate efflorescences and crusts
No full textSalt weathering is one of the most damaging processes affecting stone conservation and represents an extensively debated topic in heritage science. The main subject of previous research is the built heritage, whereas other types of assets are often neglected, such as underground cultural heritage. This paper introduces an investigation of stone decay in the subterranean environment focused on salt weathering, its patterns, compositional features, and variability in time and space, aiming at finding its driving forces in the rock properties and environmental setting. Field explorations and the mineralogical analysis of salt efflorescences and crusts were integrated by the petrographic, geochemical, and petrophysical characterization of the rock substrates, a microclimate monitoring, and the chemical analysis of groundwater and rainwater. The subject of study is the underground archaeological-historical site of Yoshimi Hyaku Ana in Japan, a complex of Kofun tombs of the 6th–7th century and galleries of the WWII era. The site is affected by intense salt weathering, involving efflorescences and crusts composed of mixed soluble sulfates, mostly hydrated: gypsum, alunogen, alum-(Na), halotrichite, epsomite, polyhalite, tamarugite, thenardite, and mirabilite. They derive principally from the dissolution of rock-forming minerals and components (pyrite, glass, feldspars, etc.) from the Miocene volcanic tuffs into which the site is excavated. The tuffs show a certain lithological diversity (e.g., glass amount and chemico-mineralogical composition) that controls the space variability of salt composition. Another major influencing factor is the underground microclimate, which also affects the time variability and seasonality of salt weathering. The innermost underground areas have an extremely high relative humidity (~100%) and are essentially salt-free, whereas, nearby the site entrances, the wider fluctuations of air temperature and humidity create conditions for salt crystallization in the dry winter season and deliquescence in summer. Depending on the solubility of each salt phase, cycles of crystallization/dissolution and hydration/dehydration can occur both seasonally and in the short-term, causing severe stresses to the stone and damage
Introduction to the special issue “Damage assessment and conservation of underground spaces as valuable resources for human activities in Italy and Japan
Full text linkThis special issue is the main scientific output of the homonymous bilateral project between Italy and Japan “Damage assessment and conservation of underground spaces as valuable resources for human activities in Italy and Japan”. The project was financed within the agreement regarding the scientific cooperation between the National Research Council of Italy (CNR) and the Japan Society for the Promotion of Science (JSPS) signed on October 23, 2011. The fund supported mutual scientific exchanges between the teams, which were led by Roberta Varriale from the Institute for Studies on the Mediterranean (ISMed), Italy and by Chiaki T. Oguchi from the Graduate School of Science
and Engineering of Saitama University, Japan during the period 2018/2019
Damage assessment and conservation of underground spaces as valuable resources for human activities in Italy and Japan
No full textThis special issue is the main scientific output of the homonymous bilateral project between Italy and Japan “Damage assessment and conservation of underground spaces as valuable resources for human activities in Italy and Japan”. The project was financed
within the agreement regarding the scientific cooperation between the National Research Council of Italy (CNR) and the Japan Society for the Promotion of Science (JSPS) signed on October 23, 2011. The fund supported mutual scientific exchanges between the teams, which were led by Roberta Varriale from the Institute for Studies on the Mediterranean (ISMed), Italy and by Chiaki T. Oguchi from the Graduate School of Science and Engineering of Saitama University, Japan during the period 2018/2019
Taya Caves, a Buddhist marvel hidden in underground Japan: stone properties, deterioration, and environmental setting
Full text linkThe Buddhist sacred site of Taya Caves is a gem hidden underground in Yokohama, Japan. The caves were excavated and sculpted into bare rock by Shingon Buddhist monks from the Kamakura until the Edo period (thirteenth–nineteenth century), and dedicated to ascetic training, rituals, and pilgrimage. They are a maze of halls and galleries decorated with hundreds of rock-cut reliefs, picturing deities and masters of Buddhism, temples and shrines, real and fantastic animals, vegetal motifs, mandalas, zodiac signs, family crests, etc. The history and rock art of Taya Caves and the urge to preserve their cultural value led to this first-ever scientific investigation, dealing with the stone properties, deterioration, and environmental setting. Textural, mineralogical, geochemical, and petrophysical investigations were combined with a microclimate monitoring and chemical analyses of groundwater and rainwater. The caves are excavated into a clay-rich fossiliferous siltstone, extremely soft and porous and highly susceptible to water-driven weathering. Water represents a constant in Taya Caves, either flowing, dripping, and stagnant; or rising from the subsoil; or related to the extremely high relative humidity. Crusts and efflorescences represent important indicators of mineral dissolution and mobilization. The crusts are made of gypsum, crystallized from the dissolution of calcareous bioclasts and oxidation of pyrite, with minor calcite. The efflorescences are composed of chlorides, phosphates, sulfates, and carbonates, possibly deriving from agrochemicals and the surface vegetation cover. The salt weathering is strictly related to the microenvironmental variables and physico-chemical properties of the phases and waters involved. Rock-water interaction is particularly damaging even considering just the physical mechanisms. The stone is strongly sensitive to water absorption, hygroscopic adsorption, and slaking: the stresses generated by in-pore water and air movement and the swelling clay minerals may lead to rapid disintegration, especially during cyclic processes. This research is expected to raise concerns about the safeguard of Taya Caves and support future monitoring and conservation plans, and to foster a wider promotion and valorization of this heritage site
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
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