Using the recently developed techniques of electron tomography, we have explored the first stages of disfiguring formation of zinc soaps in modern oil paintings. The formation of complexes of zinc ions with fatty acids in paint layers is a major threat to the stability and appearance of many late 19th and early 20th century oil paintings. Moreover, the occurrence of zinc soaps in oil paintings leading to defects is disturbingly common, but the chemical reactions and migration mechanisms leading to large zinc soap aggregates or zones remain poorly understood. State-of-the-art scanning (SEM) and transmission (TEM) electron microscopy techniques, primarily developed for biological specimens, have enabled us to visualize the earliest stages of crystalline zinc soap growth in a reconstructed zinc white (ZnO) oil paint sample. In situ sectioning techniques and sequential imaging within the SEM allowed three-dimensional tomographic reconstruction of sample morphology. Improvements in the detection and discrimination of backscattered electrons enabled us to identify local precipitation processes with small atomic number contrast. The SEM images were correlated to low-dose and high-sensitivity TEM images, with high-resolution tomography providing unprecedented insight into the structure of nucleating zinc soaps at the molecular level. The correlative approach applied here to study phase separation, and crystallization processes specific to a problem in art conservation creates possibilities for visualization of phase formation in a wide range of soft materials.

The Varna I cemetery, on the Bulgarian Black Sea coast, is one of the most remarkable sites in European prehistory, with the world’s earliest large-scale assemblage of gold artifacts. Modeling of the first series of 14 accelerator mass spectrometry (AMS) dates yielded a duration of occupation at the site of ca. 150 years, ~4600–4450 cal BC. However, there were insufficient paired human–animal dates for a full consideration of the question of the marine reservoir effect. Here, a fuller set of 71 dates from 53 graves is presented. We identify a small reservoir effect in a number of individuals based on 14C, as well as carbon and nitrogen stable isotopes. We test the effect of this by building a series of different Bayesian models. Our favored model, including a correction for some of the human determinations, shows activity at the cemetery starting at 4596–4516 cal BC and ending 4427–4341 cal BC (at 95.4% probability). The overall span of activity covers ~120–260 years (93.6% prob.). The modeling shows that Varna I falls toward the beginning of the Bulgarian Late Copper Age.

In order to extend diagnoses of recent sea-ice variations beyond the past few decades, a century-scale digital dataset of Arctic sea-ice coverage has been compiled. For recent decades, the compilation utilizes satellite-derived hemispheric datasets. Regional datasets based primarily on ship reports and aerial reconnaissance are the primary inputs for the earlier part of the 20th century. While the various datasets contain some discrepancies, they capture the same general variations during their period of overlap. The outstanding feature of the time series of total hemispheric ice extent is a decrease that has accelerated during the past several decades. The decrease is greatest in summer and weakest in winter, contrary to the seasonality of the greenhouse changes projected by most global climate models. The primary spatial modes of sea-ice variability diagnosed in terms of empirical orthogonal functions, also show a strong seasonality. The first winter mode is dominated by an opposition of anomalies in the western and eastern North Atlantic, corresponding to the well-documented North Atlantic Oscillation. The primary summer mode depicts an anomaly of the same sign over nearly the entire Arctic and captures the recent trend of sea-ice coverage.

Sea-ice thickness distributions from 12 submarine cruises under the North Pole are used to evaluate and enhance the results of sea-ice model simulations. The sea-ice models include versions with cavitating fluid and elastic-viscous-plastic rheologies, and versions with a single thickness and with multiple (5–27) thicknesses in each gridcell. A greater portion of the interannual variance of observed mean thickness at the Pole is captured by the multiple-thickness models than by the single-thickness models, although even the highest correlations are only about 0.6. After The observed thickness distributions are used to ˚tune" the model to capture the primary mode of the distribution, the largest model-data discrepancies are in the thin-ice tail of the distribution. In a 41 year simulation ending in 1998, the model results show a pronounced decrease of mean ice thickness at the Pole around 1990; the minimum simulated thickness occurs in summer 1998. The decrease coincides with a shift of the Arctic Oscillation to its positive phase. The smallest submarine-derived mean thickness occurs in 1990, but no submarine data were available after 1992. The submarine-derived thicknesses for 1991 and 1992 are only slightly smaller than the 12–case mean.

The aim of this work is to better understand fluid displacement mechanisms at the pore scale in relation to capillary-filling rules. Using specifically designed micro-models we investigate the role of pore body shape on fluid displacement during drainage and imbibition via quasi-static and spontaneous experiments at ambient conditions. The experimental results are directly compared to lattice Boltzmann (LB) simulations. The critical pore-filling pressures for the quasi-static experiments agree well with those predicted by the Young–Laplace equation and follow the expected filling events. However, the spontaneous imbibition experimental results differ from those predicted by the Young–Laplace equation; instead of entering the narrowest available downstream throat the wetting phase enters an adjacent throat first. Thus, pore geometry plays a vital role as it becomes the main deciding factor in the displacement pathways. Current pore network models used to predict displacement at the field scale may need to be revised as they currently use the filling rules proposed by Lenormand et al. (J. Fluid Mech., vol. 135, 1983, pp. 337–353). Energy balance arguments are particularly insightful in understanding the aspects affecting capillary-filling rules. Moreover, simulation results on spontaneous imbibition, in excellent agreement with theoretical predictions, reveal that the capillary number itself is not sufficient to characterise the two phase flow. The Ohnesorge number, which gives the relative importance of viscous forces over inertial and capillary forces, is required to fully describe the fluid flow, along with the viscosity ratio.

Two strategies for social relations are defined for the Neolithic and Chalcolithic of south-eastern Europe: enchainment and commodification. Enchained relations are based upon inalienable objects exchanged between relations, while barter relations are concerned with the re-contextualisation of exotic objects into local communities. The metaphor of fragmented artefacts is explored in relation to enchained relations, while those complete objects subject to formal deposition are interpreted as symbolising integral social relations. Fragmentation analysis conducted for a variety of materials indicates the varying potential of fired clay and metals (copper and gold) for relations based on enchainment.

The social practices surrounding fragmentation and structured/formal deposition are explored in two socia-spatial contexts - the domestic arena and the mortuary arena. Fragmentation of figurines is analysed at the late Copper Age tell of Goljamo Delcevo, in north-eastern Bulgaria. By contrast, three north-eastern Bulgarian Copper Age cemeteries are analysed to examine the extent to which material culture is used to express gendered social competition in the mortuary domain. It is proposed that the tension between enchained relations and commodification is one of the key factors in the generation of dynamic hange in the Balkan Copper Age, at the time of the Varna cemetery.

This paper is a study of diet and subsistence among Mesolithic and Early Neolithic populations in the Iron Gates section of the Danube Valley, with emphasis on the sites of Lepenski Vir and Vlasac in Serbia and Schela Cladovei in Romania. The first part of the paper reviews the evidence of animal and plant residues and human skeletal indicators; the second presents new data from stable isotopic analyses of human bone supported by AMS 14C dates. Isotopic and dental evidence suggest that Mesolithic people prior to 7600 BP had high protein diets in which the bulk of the protein was derived from riverine food sources. Significant differences are evident between the isotopic signals of Mesolithic males and females buried at Vlasac and Lepenski Vir, indicating differences in overall diet. These differences are most easily explained in terms of movement of individuals between groups, linked to the practice of local group exogamy. A shift in dietary pattern occurred at Lepenski Vir between ca 7600 and 7300 BP. The bone chemistry of individuals post-dating 7300 BP reflects the intake of significantly higher proportions of terrestrial foods. This change may reflect the introduction of stock-raising and/or cultivation in the Iron Gates. If so, then the transition from Late Mesolithic to Neolithic at Lepenski Vir was not characterised by a wholesale shift in subsistence from foraging to farming; the earliest Neolithic inhabitants of the site continued to obtain a significant proportion of their dietary protein from riverine resources. The wider implications of the AMS dates and stable isotopic data are also considered.

Ceramics were subjected to organic residue analysis from two collections: a series of middle Copper Age (Bodrogkeresztúr) vessels hitherto known as ‘milk jugs’, curated in the Magyar Nemzeti Múzeum, Budapest, and a collection of early Baden (Boleráz) vessels from the recently discovered settlement of Gyo”r-Szabadrét-domb, in western Hungary. The aim of the analyses was to establish whether or not these vessels, often associated with milk based on typological criteria, were actually used to process, store or serve dairy products. The results of the analyses revealed that no dairy products could be securely identified in the so-called ‘milk jugs’. Nevertheless dairy products were identified in other vessel types.

In this article we outline some of the key characteristics of the social structure of the Climax Copper Age in the eastern Balkans and the contributions of the Varna cemetery to those developments. We continue by examining the implications of the new series of 21 AMS dates from the Oxford Radiocarbon Laboratory, which represent the first dates for the Varna Eneolithic cemetery on the Bulgarian Black Sea coast. Representing the first phase of the AMS dating project for the Varna I cemetery, these dates have been selected to provide a range of different grave locations, ranges of grave goods, and age/gender associations. We conclude by addressing the question of the unexpectedly early start of the cemetery, as well as its apparently short duration and relatively rapid demise.