ABSTRACT
Visualizing the internal structure of museum objects is a crucial step in acquiring knowledge about the origin, state, and composition of cultural heritage artifacts. Among the most powerful techniques for exposing the interior of museum objects is computed tomography (CT), a technique that computationally forms a 3D image using hundreds of radiographs acquired in a full circular range. However, the lack of affordable and versatile CT equipment in museums, combined with the challenge of transporting precious collection objects, currently keeps this technique out of reach for most cultural heritage applications. We propose an approach for creating accurate CT reconstructions using only standard 2D radiography equipment already available in most larger museums. Specifically, we demonstrate that a combination of basic X-ray imaging equipment, a tailored marker-based image acquisition protocol, and sophisticated data-processing algorithms, can achieve 3D imaging of collection objects without the need for a costly CT imaging system. We implemented this approach in the British Museum (London), the J. Paul Getty Museum (Los Angeles), and the Rijksmuseum (Amsterdam). Our work paves the way for broad facilitation and adoption of CT technology across museums worldwide.
ABSTRACT
Dating the wood from historical art objects is a crucial step to ascertain their production time, and support or refute attribution to an artist or a workshop. Dendrochronology is commonly used for this purpose but requires access to the tree-ring pattern in the wood, which can be hindered by preparatory layers, polychromy, wax, or integrated frames. Here we implemented non-invasive dendrochronology based on X-ray computed tomography (CT) to examine a painting on panel attributed to Rubens' studio and its presumed dating around 1636 CE. The CT images achieved a resolution of 37.3 micron and revealed a double panelling, which was concealed by oak strips covering all four edges. The back (visible) board is made of deciduous oak (Quercus subg. Quercus), the most common type of wood used in 17th-century Netherlandish workshops, and was dated terminus post quem after 1557 CE. However, the front (original) board used for the painting has been identified through examination of the wood anatomy as a tropical wood, probably Swietenia sp., a species seldom used in Netherlandish paintings, and remains undated. Its very presence attests the global character of 17th-century trade, and demonstrates the use of exotic species in Flemish studios. The date of the oak board refutes previous results and suggests that this board was trimmed to meet the size of the tropical one, having been glued to it for conservation purposes or with deceiving intentions to pretend that the painting was made on an oak panel. These revelations have opened new lines of art historical inquiry and highlight the potential of X-ray CT as a powerful tool for non-invasive study of historical art objects to retrieve their full history.
Subject(s)
Paintings , Radiometric Dating/methods , History, 17th Century , Paintings/history , Quercus/chemistry , Tomography, X-Ray Computed , Wood/anatomy & histologyABSTRACT
Dendrochronology is an essential tool to determine the date and provenance of wood from historical art objects. As standard methods to access the tree rings are invasive, X-ray computed tomography (CT) has been proposed for non-invasive dendrochronological investigation. While traditional CT can provide clear images of the inner structure of wooden objects, it requires their full rotation, imposing strong limitations on the size of the object. These limitations have previously encouraged investigations into alternative acquisition trajectories, including trajectories with only linear movement. In this paper, we use such a line-trajectory (LT) X-ray tomography technique to retrieve tree-ring patterns from large wooden objects. We demonstrate that by moving a wooden artifact sideways between the static X-ray source and the detector during acquisition, sharp reconstruction images of the tree rings can be produced. We validate this technique using computer simulations and two wooden test planks, and demonstrate it on a large iconic chest from the Rijksmuseum collection (Amsterdam, The Netherlands). The LT scanning method can be easily implemented in standard X-ray imaging units available at museum research facilities. Therefore, this scanning technique represents a major step towards the standard implementation of non-invasive dendrochronology on large wooden cultural heritage objects.
ABSTRACT
Background This research is an investigation into the role of expert quotes in health news, specifically whether news articles containing a quote from an independent expert are less often exaggerated than articles without such a quote. Methods Retrospective quantitative content analysis of journal articles, press releases, and associated news articles was performed. The investigated sample are press releases on peer-reviewed health research and the associated research articles and news stories. Our sample consisted of 462 press releases and 668 news articles from the UK (2011) and 129 press releases and 185 news articles from The Netherlands (2015). We hand-coded all journal articles, press releases and news articles for correlational claims, using a well-tested codebook. The main outcome measures are types of sources that were quoted and exaggeration of correlational claims. We used counts, 2x2 tables and odds ratios to assess the relationship between presence of quotes and exaggeration of the causal claim. Results Overall, 99.1% of the UK press releases and 84.5% of the Dutch press releases contain at least one quote. For the associated news articles these percentages are: 88.6% in the UK and 69.7% in the Netherlands. Authors of the study are most often quoted and only 7.5% of UK and 7.0% of Dutch news articles contained a new quote by an expert source, i.e. one not provided by the press release. The relative odds that an article without an external expert quote contains an exaggeration of causality is 2.6. Conclusions The number of articles containing a quote from an independent expert is low, but articles that cite an external expert do contain less exaggeration.
ABSTRACT
Objective: To determine how often press releases and news articles contain exaggeration and to locate its origin in the trajectory from research paper to news article. Design: Retrospective quantitative content analysis. Method: We analysed press releases on health-related research published by Dutch universities and university medical centres in 2015 (n = 129) as well as news media articles related to those press releases (n = 185). Results: 20% of press releases and 29% of news articles exaggerated the conclusion or causal claim. Explicit health advice was, when present, exaggerated in 7% of press releases and 10% of news articles. When press releases exaggerated the conclusion or causal claim, 92% of associated news articles contained the same exaggeration. When the conclusion was not exaggerated in the press release, 6% of the news articles was exaggerated. The relative chance for exaggerated news associated with exaggerated press releases was 16.08 (95% CI: 7.35-35.18). Exaggerated press releases were associated with news articles more frequently. The relative chance for news articles to be associated with exaggerated press releases vs. a non-exaggerated press release was 1.45 (95% CI: 1.02-2.04). Conclusion: Exaggeration in health-related news is strongly correlated with exaggeration in the original press release and occurs in more than 1 in 5 articles. Monitoring and, if necessary, improving the accuracy and correctness of academic press releases seem to be important measures to improve the quality of health related news.Conflict of interest and financial support: I. Smeets is a columnist with one of the newspapers investigated. She was not involved in collecting, coding and analysing the relevant data. Additional potential conflicts of interest have been reported for this article. ICMJE forms provided by the authors are available online along with the full text of this article.
