1,720,975 research outputs found
Hyperspectral imaging-based approach for the in-situ characterization of ancient Roman wall paintings.
No full textA diagnostic study was recently carried out on fragments of wall paintings belonging to the decorations of an ancient Roman residential villa of the Ager Gabinus, in the locality Pratolungo (Rome, Italy). The study was organized as follows: a first phase, in which small splinters of these painted specimens were embedded in resin and characterized by optical microscopy on polished cross-sections and thin sections; a second phase, in which the specimens were analyzed by Raman spectroscopy and hyperspectral imaging (HSI). The aim of the present work is to verify the potential use in situ of HSI technique in the range of SWIR (1000 nm - 2500 nm), presenting many advantages to punctual techniques of analysis as, i.e., Raman spectroscopy. In particular, the results obtainable by classical methods, such as optical microscopy, were compared to information resulting from non-destructive investigation techniques, as precisely the HSI. The acquired hyperspectral images were processed applying chemometric methods which allow not only the exploration of the data but also their recognition and their distribution over the whole specimen, without sampling. In fact, the use of HSI as a diagnostic tool in the field of cultural heritage is of great interest and it presents high potentialities, being this analysis non-destructive, non-invasive and almost portable. Furthermore, the possibility to couple hyperspectral data with chemometric techniques allows getting qualitative and/or quantitative information on the nature and physical-chemical characteristics of the investigated materials. Combining the results obtained on the samples by HSI and the results by Raman spectroscopy, it is possible to obtain information comparable with optical microscopy, allowing the identification of pigments and the constituent materials, confirming the potential use of this technique as a portable one
IDENTIFICAZIONE DI PIGMENTI IN STRATI PITTORICI MEDIANTE IMPIEGO DI IMAGING IPERSPETTRALE
No full textLa possibilità di poter caratterizzare i pigmenti all’interno di uno strato pittorico
rappresenta una sfida nello studio dei dipinti, soprattutto mediante l’impiego di tecniche
analitiche non distruttive e non invasive.
L'utilizzo dell’imaging iperspettrale (HSI) come tecnica diagnostica per l’analisi degli strati
pittorici e la valutazione dello stato di conservazione, appare di grande interesse per le sue
potenzialità. Tale tecnica di analisi, infatti, è di tipo non distruttivo, non invasivo e, con
implementazioni dell’hardware, può diventare portatile. La sua combinazione con tecniche
chemiometriche permette di ottenere dati qualitativi e/o quantitativi sulle caratteristiche
chimico-fisiche dei materiali investigati. Lo studio in corso [1-4] si pone quale obiettivo
quello di valutare le possibilità offerte da un tale approccio analitico per l’identificazione
dei pigmenti in strati pittorici. I sistemi iperspettrali impiegati sono ImSpectorTM V10E
(range spettrale VIS-NIR da 400 a 1000 nm) e SISUCHEMA XL ImSpectorTM N25 (range
spettrale SWIR da 1000 a 2500 nm). Vengono qui presentati alcuni dei risultati ottenuti
dallo studio effettuato sui primi sei pigmenti presi in esame (ocra rossa, ocra gialla, giallo
cromo, blu minerale, verde di cobalto e malachite), mescolati con quattro differenti leganti
(gomma arabica, guazzo, tempera d’uovo, olio di lino con resine alchidiche) ed applicati su
due tipologie di supporto pittorico (legno e tela). I provini di riferimento così realizzati
sono stati acquisiti con HSI; i dati ottenuti (ipercubo) sono stati poi elaborati con metodi
chemiometrici: Principal Component Analysis (PCA) e Partial Least Square-Discriminant
Analysis (PLS-DA), mediante software PLS_Toolbox (Version 7.3, Eigenvector Research,
Inc.) e Matlab® (Version 7.11.1 The Mathworks, Inc.). I primi risultati relativi ai sei
pigmenti in esame, soprattutto nel range dello SWIR, hanno dimostrato che esiste una
correlazione tra le firme spettrali dei pigmenti in polvere analizzati e quelle dei campioni
realizzati mescolando i sei pigmenti con i quattro leganti applicati sui due supporti,
prospettando, dunque, nuovi scenari analitici per la caratterizzazione degli strati pittorici.
L'approccio analitico sviluppato permette di ottenere in maniera rapida e non distruttiva
informazioni non solo sul tipo di pigmento, ma anche sul legante e sul supporto. Scopo
ultimo è quello di aumentare i casi di studio su cui applicare la metodica: si stanno
attualmente preparando e analizzando nuovi provini di pigmenti con diverse combinazioni
di strati pittorici, al fine di condurre nuovi test non solo su campioni tal quali ma anche
invecchiati in solar box con differenti tempi di esposizione.
Un tale approccio analitico potrebbe consentire di eseguire un monitoraggio completo dello
stato di conservazione di una superficie dipinta così come la caratterizzazione dei suoi
materiali costitutivi, in confronto con altre tecniche analitiche convenzionali
Microclimatic Monitoring for Archeological Shelters Across Indoor Comfort and Conservation: The Case Study of the Villa del Casale in Piazza Armerina (Sicily, Italy)
No full textConservation and use raise priority and complementary needs in the archeological built heritage and, within the contemporary paradigm, they are no longer conflictual activities. The minimum intervention principle and compatibility are key objectives to avoid altering the values of the heritage. However, the musealization process also requires a double focus: on the one hand, the conservation of the material asset; on the other, the well-being of the users. The influence of environmental parameters on material decay is a well-known item: this occurs through chemical, physical, and biological processes, which contribute to reducing the expected life of archeologi- cal finds. Furthermore, the conditions of thermo-hygrometric comfort are necessary to guarantee the correct use of the site. The paper focuses on the thermo-hygrometric well-being in archeological sites and, in particular, on the case of Villa Romana del Casale, in Piazza Armerina, Sicily, which is a UNESCO site. A complex restoration project was performed on this site a few decades ago, aimed at improving the conservation of the mosaic apparatuses and users’ well-being, through the redesign and consequent replacement of the shelter system. The microclimate monitoring, aimed to verify the environmental conditions created by the new covering system, has been focused on sample room, on which the new covering system has been completed, and rooms that still are covered by the methacrylate old system. The comparison between the environmental parameters related to the old covering system, which caused undesired effects both for use and conservation, and the data related to the new covering system, allowed verifying the improvement in microclimatic conditions after the intervention. Data have demonstrated that the new one has reduced temperature inside the rooms and has increased humidity values. These analytical data demonstrate that the conservative intervention provided a positive impact on microclimatic conditions. Indeed, the comparison also showed the absence of the dangerous greenhouse effect. The conclusion of the paper will propose a comparative analysis of these results and other general aspects of the quality of the intervention, which cannot be measured or can only be measured indirectly
“A warning from Mars”: effect of microclimate changes at the Specola Museum of Palermo
Full text linkThe Specola Museum is located at the Palermo Astronomical Observatory and preserves most of its material heritage. It is part of the Museum System of the University of Palermo (SiMuA) and its management and conservation are entrusted to the INAF - Astronomical Observatory of Palermo. Among the historical instruments on display, there is a 19th-century painted wooden globe reproducing the surface of Mars. It has been on display in a showcase, inside the Merz Telescope Hall, for about 20 years without undergoing any type of intervention or evident deterioration sign. From 2021, in less than two years, damages of its pictorial layers occurred at a progressive rate. The European Standard EN 15757 explains that hygroscopic materials are highly vulnerable to microclimate changes. The wooden globe was in good conditions after two decades of permanence at the museum, but the recent control and management of the indoor climate was not compatible with the past climate history of the globe to which it has adapted.
The speed of the degradation made it evident that the microclimatic conditions of the room changed abruptly. The warning deduced from the Mars globe deterioration was hence easy to decode: there is something wrong with this climate!
It is well known that museum microclimate plays a key role in the conservation of the objects on display. It may trigger or aggravate degradation processes of the materials constituting the object exhibited and affect their “life expectancy”. Moreover, each object responses peculiarly to environment variability, depending on its composition and conservation history. When an artifact is composed of different materials, unexpected synergistic effects may develop. Finding appropriate values range of temperature, relative humidity and illuminance and managing them to guarantee the conservation of the entire collection, and at the same time improving the thermal comfort for people working there, is a difficult task. The issue becomes even more challenging in buildings not originally designed for conservation purposes, as the Specola Museum, located in the ancient observatory rooms, built in 1790 on the top of the 12nd-century Royal Palace.
An accurate restoration has been made, and conservation measures have been adopted, to stop the serious deteriorating processes affecting the model of Mars but the risk of further deterioration phenomena involving other objects is expected to increase substantially if no actions are taken.
This contribution intends to present the results of the preliminary study concerning the thermo-hygrometric records taken in the Merz Telescope Hall over the last two years and propose specific actions to improve its microclimate conditions.
References
Carotenuto M. R., Randazzo D., Chinnici I., Genua G., Preventive Conservation Projects on LAM Materials at the INAF-Astronomical Observatory of Palermo “G.S. Vaiana”, Bulletin of the AAS, 54(2) (2022)
Carotenuto M. R., Chinnici I. et al., Rapporto tecnico INAF 2022 - Il Museo della Specola: progetti per la conservazione, la fruizione, la comunicazione (2018-2020)
Camuffo D., Microclimate for cultural heritage. Measurement, Risk Assessment, Conservation, Restoration, and Maintenance of Indoor and Outdoor Monuments, Elsevier, third Edition (2019)
Antomarchi C., Pedersoli Jr., Michalski S., Guide to Risk Management, ICCROM (2016)
Foderà Serio G., Chinnici I., L'Osservatorio Astronomico di Palermo, Palermo (1997
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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