Search results for "complex"
showing 10 items of 5889 documents
Halloysite Nanotubes Loaded with Calcium Hydroxide: Alkaline Fillers for the Deacidification of Waterlogged Archeological Woods
2018
A novel green protocol for the deacidifying consolidation of waterlogged archaeological woods through aqueous dispersions of polyethylene glycol (PEG) 1500 and halloysite nanotubes containing calcium hydroxide has been designed. First, we prepared functionalized halloysite nanotubes filled with Ca(OH)2 in their lumen. The controlled and sustained release of Ca(OH)2 from the halloysite lumen extended its neutralization action over time, allowing the development of a long-term deacidification of the wood samples. A preliminary thermomechanical characterization of clay/polymer nanocomposites allows us to determine the experimental conditions to maximize the consolidation efficiency of the wood…
Machine learning for rapid mapping of archaeological structures made of dry stones – Example of burial monuments from the Khirgisuur culture, Mongoli…
2020
11 pages; International audience; The present study proposes a workflow to extract from orthomosaics the enormous amount of dry stones used by past societies to construct funeral complexes in the Mongolian steppes. Several different machine learning algorithms for binary pixel classification (i.e. stone vs non-stone) were evaluated. Input features were extracted from high-resolution orthomosaics and digital elevation models (both derived from aerial imaging). Comparative analysis used two colour spaces (RGB and HSV), texture features (contrast, homogeneity and entropy raster maps), and the topographic position index, combined with nine supervised learning algorithms (nearest centroid, naive…
Social differentiation and land use at an Early Iron Age “princely seat”: bioarchaeological investigations at the Glauberg (Germany)
2014
Excavations at the late Hallstatt/early La Tene (6th–4th century BC) “princely seat” of the Glauberg (Hesse, Germany) revealed exceptionally furnished graves in monumental mounds, simple inhumations in associated ditches and non-normative burials of up to eight individuals in conical storage pits. The study presented here addresses bioarchaeological characteristics of these burials and their implications for social differentiation and the sphere of influence of the “princely seat”. It includes osteological, aDNA, and multi-isotope analyses of 27 human individuals and faunal remains. One of the outstandingly rich graves (tumulus 1/grave 1) contained the skeleton of a young man (the “prince”)…
Ivory in the Chalcolithic enclosure of Perdigões (South Portugal): the social role of an exotic raw material
2015
AbstractThis article discusses the social role played by ivory and ivory articles in the Perdigoes enclosures (South Portugal) during the Chalcolithic (third millennium bc), in the context of the emergence and development of social complexity on the Iberian Peninsula. Perdigoes is a Portuguese prehistoric site with some of the highest concentrations of ivory objects known in Iberia and with the greatest variety. The contexts, almost exclusively funerary, are discussed along with the results of provenance studies. Comparing the different contexts and the categories of objects made of ivory makes it possible to distinguishing a variety of active social dimensions (such as individual status, g…
Preservation of fungi in archaeological charcoal
2010
During the analysis of wood charcoal remains from archaeological sites, it is common to find different microorganisms and different forms of degradation present in the plant tissue. However, one may encounter difficulties when attempting to identify these microorganisms and determine when their attack occurred. This paper focuses on preservation aspects related to the microorganisms in wood and demonstrates the structural changes that take place in different types of decayed wood after it was converted into charcoal. The study seeks to determine whether the microbial attack found in archaeological woods took place before the burning of the wood or after. Burning experiments were conducted u…
POROSITY DETERMINATION WITH HELIUM PYCNOMETRY AS A METHOD TO CHARACTERIZE WATERLOGGED WOODS AND THE EFFICACY OF THE CONSERVATION TREATMENTS
2012
The helium pycnometer allows us to measure the cell-wall density of dry woods and the basic density of wood samples soaked with water and/or a consolidant solution if a non-volatile solvent is used. These parameters were correlated to the porosity, which for degraded waterlogged wood is related to the maximum water content. Moreover, this has revealed the possibility of investigating, by means of accurate cell-wall density determination, the efficacy of several consolidants in the treatment of waterlogged woods.
‘Adaptive cycles’ and climate fluctuations: a case study from Linear Pottery Culture in western Central Europe
2014
Abstract By applying cycle-based resilience theory the dynamics of the Early Neolithic west-central European Linear Pottery Culture (LBK) are investigated. These are interpreted as resulting from a combination of internal socio-economic processes as well as external environmental parameters. Resilience theory is helpful in understanding periods of increased vulnerability and inherent trends to social complexity. Cycles and threshold levels also help to understand why societies experience periods of increasing fragility and subsequent decline. Results are based on the correlation of a typology and dendrochronology-based archaeological chronology for western LBK and various palaeoclimatic pro…
Słabości eksplanacyjne teorii inteligentnego projektu
2021
Artykuł powstrzymuje się od polemiki merytorycznej z teorią inteligentnego projektu, dalej TIP, a jedynie wskazuje na jej niedostatki metodologiczne. Dowodzi, że wbrew twierdzeniom jej zwolenników TIP nie jest falsyfikowalna. W odróżnieniu od teorii ewolucji nie może pełnić nawet roli metafizycznego programu badawczego w sensie Poppera. Co jednak ważniejsze, TIP nie pełni żadnych funkcji eksplanacyjnych. W grę wchodzą jedynie wyjaśnienia intencjonalne, TIP zaś nie jest w stanie zidentyfikować motywów domniemanego projektanta. Argument jest zilustrowany przykładami zaczerpniętymi od Stanisława Lema, które pokazują, że możliwych jest wiele alternatywnych hipotez na temat celów domniemanego pr…
Temperature dependence of the rate constant of hydrogen isotope interactions with a lithium capillary-porous system under reactor irradiation
2013
Abstract Experiments with a sample of a lithium capillary-porous system (CPS) were performed at the reactor IVG-1.M of the Institute of Atomic Energy NNC RK to study the effects of neutron irradiation on the parameters of hydrogen isotope interactions with a lithium CPS. The absorption technique was used during the experiments, and this technique allowed the temperature dependences of the hydrogen isotope interaction rate constants with the lithium CPS to be obtained under various reactor powers. The obtained dependencies were used to determine the main interaction parameters: the activation energies and the pre-exponents of the Arrhenius dependence of the hydrogen interaction rate constant…
Optimal Guard Placement Problem Under L-Visibility
2006
Two points a and b in the presence of polygonal obstacles are L-visible if the length of the shortest path avoiding obstacles is no more than L. For a given convex polygon Q, Gewali et al [4]. addressed the guard placement problem on the exterior boundary that will cover the maximum area exterior to the polygon under L-visibility. They proposed a linear time algorithm for some given value of L. When the length L is greater than half of the perimeter, they declared that problem as open. Here we address that open problem and present an algorithm whose time complexity is linear in number of vertices of the polygon.