Critical evaluation of in situ analyses for the characterisation of red pigments in rock paintings: A case study from El Castillo, Spain

Paint technology, namely paint preparation and application procedures, is an important aspect of painting traditions. With the expansion of archaeometric studies and in situ non-destructive analytical methods, a renewal of technological studies is being observed in rock art. In situ analyses have several limitations that are widely discussed in the literature, however. It is not yet clear whether they provide accurate information on paint technology, except under certain conditions. Here, we evaluated digital microscopic and pXRF in situ analyses for the characterisation of a large set of red and yellow paintings from the El Castillo cave, Cantabria, Spain. We have set experiments and used statistical methods to identify differences between paint components and determine factors impacting pXRF measurements. We found that the compositional heterogeneity of the paintings’ environment, especially variations in secondary deposits, was responsible for most of the differences observed between the pXRF signals recorded on the paintings. We concluded that the El Castillo cave environment is not suitable for non-destructive technological studies, but that more favourable contexts might exist. Following previous works and our own results, we advocate a combination of both in situ and laboratory invasive analyses for the study of paint composition and paint technology. Our research protocol, based on the comparison of rock paintings, their substrate, experimental paintings and Fe-normalisation of the signals can improve the reliability of pXRF results. We also propose to include more systematic characterisation of rock wall heterogeneity and the use of microscopic analyses in non-destructive approaches.publishedVersio

Fluorescence UV des liants employés dans les dorures sur peintures murales médiévales

Les peintures de la chapelle de l’ancien logis abbatial de Moissac ont été examinées in situ sous éclairage UV. La présence de fluorescences jaunes sur les auréoles de certains personnages s’est révélée être l’indicateur de l’existence d’une ancienne dorure. Des fluorescences de ce type, caractéristiques d’un liant organique, ont déjà été observées dans d’autres sites où des traces de dorure sont également présentes. Une étude par spectrofluorimétrie montre que les spectres de fluorescence des deux types chimiques de liants les plus couramment employés dans la technique de la dorure sont différents. Pour se rapprocher de l’état d’altération des liants anciens, une étude de l’évolution de la fluorescence après vieillissement accéléré, a également été conduite.Paintings of the vault of the old abbey home of Moissac were examined using a UV source. The presence of yellow fluorescence on the halos figures is an indicator of the presence of historical gilding. Fluorescence of this type, characteristic of an organic binder, was already observed in other sites where traces of gilding are also present. A spectrofluorimetric study shows that the fluorescence spectra of the two chemical types of binders most usually used in the technique of gilding are different. To better understand the condition of aged binders, a study of the fluorescence evolution following accelerated ageing was also carried out

Exploring the Performance of Methods to Deal Multicollinearity: Simulation and Real Data in Radiation Epidemiology Area

The issue of multicollinearity has long been acknowledged in statistical modelling; however, it is often untreated in the most of published papers. Indeed, the use of methods for multicollinearity correction is still scarce. One important reason is that despite many proposed methods, little is known about their strength or performance. We compare the statistical properties and performance of four main techniques to correct multicollinearity, i.e., Ridge Regression (R-R), Principal Components Regression (PC-R), Partial Least Squares Regression (PLS-R), and Lasso Regression (L-R), in both a simulation study and two real data examples used for modelling volumes of heart and Thyroid as a function of clinical and anthropometric parameters. We find that when the statistical approaches were used to address different levels of collinearity, we observed that R-R, PC-R and PLS-R appeared to have a somewhat similar behavior, with a slight advantage for the PLS-R. Indeed, in all implemented cases, the PLS-R always provided the smallest value of root mean square error (RMSE). When the degree of collinearity was moderate, low or very low, the L-R method had also somewhat similar performance to other methods. Furthermore, correction methods allowed us to provide stable and trustworthy parameter estimates for predictors in the modelling of heart and Thyroid volumes. Therefore, this work will contribute to highlighting performances of methods used only for situations ranging from low to very high multicollinearity

Impact of Individuals' Commuting Trips on Subjective Well-being: Evidence from Xi’an

Transportation as an important component for urban sustainability has been well recognized. Although the lay understanding of sustainability generally focuses on environmental stewardship, more broadly sustainability is comprised of three aspects: environmental, economic and social sustainability. Individual and societal well-being are critical indicators of social sustainability, however, little attention from research and policy has been paid to the impacts of transportation on well-being. With extensive urban expansion resulting from rapid urbanization, commuting has become a physical and mental burden for many residents in the megacities of China because of the increasing travel distances and worsening travel experiences, significantly influencing their well-being. Relying on the data from a survey conducted in Xi-an, a mega-city of western China, this study quantitatively investigated the relationship between commuting and subjective wellbeing in the Chinese context. Based on the evidence from Xi-an, China, this study found that (1) commute characteristics, including travel mode choice and level of services, significantly influence commuting satisfaction, which in turn significantly affects overall satisfaction with life; (2) the built environment has no direct effect on commuting satisfaction, however it could indirectly affect commuting satisfaction through the path of commuting characteristics; most of travel-related attitudes have both direct and indirect effects on travel satisfaction; (3) the lower income population are more likely to live in pedestrian and transit unfriendly places, are more captive to their travel modes, and have lower levels of life satisfaction; all of which contribute to the lower level of commuting satisfaction among the lower income population. This study contributes to the literature by framing and quantitatively exploring the complicated relationships between the built environment, attitudes, travel characteristics, travel satisfaction and subjective wellbeing. This study also informs policies that help to improve satisfaction with commuting and wellbeing

Recent Laborian of the Peyrazet cave-rock shelter (Creysse, Lot, France). New data for the end of Lateglacial in Quercy

Découverte en 1990, la grotte-abri de Peyrazet (Creysse, Lot, France) se situe dans le Haut-Quercy en bordure du causse de Martel, à quelques centaines de mètres du cours actuel de la Dordogne. Les fouilles menées depuis 2008 livrent une archéoséquence du Tardiglaciaire qui permet de combler certaines lacunes documentaires régionales et plus largement du Sud-Ouest de la France. Au Magdalénien supérieur succède un niveau ayant donné des indices d’un Azilien sensu lato stratigraphiquement séparé du Laborien, ensemble supérieur qui fait l’objet de cet article. Jusqu’alors ce technocomplexe de la fin du Pléistocène et des débuts de l’Holocène demeurait mal connu dans la région. En effet, seuls des travaux anciens menés dans deux gisements permettaient de noter sa présence en Quercy. La découverte d’un ensemble laborien récent (ou Épilaborien) à Peyrazet est l’occasion de conduire une étude collective des divers vestiges dans un cadre archéostratigraphique mieux maîtrisé. L’analyse géoarchéologique met en évidence l’action conjointe du ruissellement et de l’éboulisation comme principaux responsables de la mise en place des dépôts. Dans la partie S-O du site, un lithofaciès de remaniement indique une bioturbation importante en lien avec le creusement de terriers. Bien que leur origine ne soit pas liée aux activités humaines, les rongeurs, les oiseaux, les poissons et les mésomammifères (excepté le lièvre) apportent des données concernant l’environnement des chasseurs-cueilleurs. La grande faune est dominée par le cerf dont les carcasses pourraient avoir été introduites incomplètes sur le site puis traitées pour en extraire la viande et la moelle. Nous avons bénéficié d’une analyse fonctionnelle croisée à l’étude typo-technologique des vestiges lithiques composés pour l’essentiel de silex locaux et régionaux. Ce double regard a permis de mettre en évidence une diversité d’activités mise en œuvre dans la cavité. Une pièce d’ocre rouge, quelques vestiges d’industrie osseuse et des éléments de parure participent également à la description d’une large gamme de tâches effectuées lors d’un séjour prolongé ou de plusieurs occupations successives. La comparaison des pointes de chasse microlithiques avec d’autres gisements sur une vaste échelle géographique conduit à discuter l’attribution de cet ensemble supérieur à différentes phases du Laborien. L’hypothèse d’un Laborien récent (ou Épilaborien) conduit à réfléchir à une perduration de morphotypes ancestraux parallèlement à de nouveaux types d’armatures, observation déjà réalisée notamment à La Borie del Rey dans le Haut-Agenais mais qui demande encore des précisions et de nouvelles découvertes.Discovered in 1990, Peyrazet cave-rock shelter (Creysse, Lot) lies in the Haut-Quercy region at the limits of the Martel limestone plateau, several hundred meters from the current Dordogne River valley. Excavations begun in 2008 produced a Late Glacial archaeo-sequence that sheds new light on several still poorly understood aspects of the archeological record in both the Haut-Quercy region and southwestern France in general. The level overlying the Late Magdalenian occupation produced limited evidence for the Azilian and is stratigraphically separated from the Laborian. This latter techno-complex, dated to the end of the Pleistocene and early Holocene, remains poorly documented in the region, having only been previously identified from two sites in the Quercy. The discovery of a recent Laborian (Epilaborian) occupation at Peyrazet presented the ideal occasion for a collaborative study of the diverse archaeological material recovered from this well-understood archaeo-stratigraphic context. A geoarchaeological analysis produced evidence for both surface runoff and the accumulation of coarse deposits (éboulis) as the principal site formation processes. In the southwest area of the site, a reworked lithofacies demonstrates substantial bioturbation in connection with animal burrowing. Although the presence of rodent, bird, fish, and medium-sized mammals (except hare) cannot be definitively connected to human activity, they nevertheless provide important information concerning the environments exploited by hunter-gatherer groups. Larger species are dominated by red deer whose carcasses were partially processed before being introduced to the site, where meat was subsequently removed and marrow consumed. A functional analysis combined with a typo-technological study of the primarily locally- and regionally-procured lithic material revealed evidence for diverse activities having taken place on-site. An ochre fragment, several bone tools and ornaments equally indicate a large variety of tasks to have been carried out during a single, long occupation or several successive visits. A typo-technological comparison of hunting weaponry (microliths) from sites across a substantial area suggests the assemblage to represent either a Laborian/Epilaborian mix or a unique Epilaborian occupation. This latter case would indicate the persistence of older morphotypes alongside the development of new tools forms, a situation already identified at Borie del Rey in the Haut-Agenais but which requires more detailed study supported by new discoveries

Pigment use from OIS 5 to 4 in South Africa: a review of the most recent researches

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Beads and pigment use at Bushman Rock Shelter, South Africa: documenting the diversity in ornamental traditions of early Holocene societies

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Defining iron-bearing rock sources in compositional data statistical analysis for provenance studies: A case study from South Africa

International audienceIn iron-bearing rock provenance researches the definition of what is a source vary from an author to another. Issues might occur when the sources are associated with complex weathering profiles. How may the definition of the source influence the results of provenance studies when different types of iron-bearing rocks are encountered within the same weathering profile? In order to deal with this research question, we used a geochemical dataset previously obtained from the study of the ochre geological collection collected around Diepkloof rock shelter, South Africa. We tested the efficiency of Linear Discriminant Analyses (LDA, supervised analysis) and Principal Component Analysis (PCA, non-supervised analysis) in source discrimination and in the attribution of archaeological pieces to the right source. Different assumptions were made: sources were defined by separating or grouping the different lithologies (shale and ferricrete) encountered at the same location. The results show that grouping the different lithologies allows a good attribution of the archaeological pieces to the source it comes from when elements positively correlated with iron are used in the analysis. Separating the different lithologies do not allow a rate of success in archaeological pieces attribution as high as when the lithologies are grouped together. This result might be explained by a highest number of samples that define a source when the different lithologies are grouped together. Further research should be considered in this direction in order to define if this is a general trend

Oxydes de fer et de manganèse dans la partie supérieure de la séquence de Combe-Grenal : de l'usage du rouge et du noir à la fin du Paléolithique moyen

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