formation morphology and interpretation of darkened faecal spherulites

Abstract Faecal spherulites are a common indicator of dung in archaeological deposits and most of the basic processes of their formation and taphonomy have been explained. However, a darkened form is also regularly found, ranging from slightly transparent through to completely opaque. These have been less well studied, so we set out here to understand what actually causes the darkening and to determine the range of conditions required to produce the changes. Darkened spherulites were successfully created by heating dung to between 500 °C and 700 °C with the gaseous products constrained. The maximum production in our experiments was at 600 °C. The darkened spherulites often expanded during the alteration process and some of the expanded ones become distorted. SEM examination was only possible through destructive preparation processes, but examples were found showing expansion beyond the normal size range. These had a distinctive internal structure characterised by very fine crystallinity and larger scale fracturing, perhaps resulting from organic matter loss and/or CaCO 3 alteration. Prolonged oxidative heating failed to remove the darkening, leading to the possibility that it is partly a structural phenomenon, with opacification arising from compound relief. Based on these findings, darkened spherulites can now be confidently interpreted as; resulting from dung being heated in conditions of limited gaseous exchange to between 500 and 700 °C, then not heated again beyond ca. 700 °C. These sorts of conditions could occur, around the edge of, or beneath, any fire where fresh dung is being burned or where the existing stratigraphy has a dung component

Reactivity mapping: electrochemical gradients for monitoring reactivity at surfaces in space and time

Studying and controlling reactions at surfaces is of great fundamental and applied interest in, among others, biology, electronics and catalysis. Because reaction kinetics is different at surfaces compared with solution, frequently, solution-characterization techniques cannot be used. Here we report solution gradients, prepared by electrochemical means, for controlling and monitoring reactivity at surfaces in space and time. As a proof of principle, electrochemically derived gradients of a reaction parameter (pH) and of a catalyst (Cu(I)) have been employed to make surface gradients on the micron scale and to study the kinetics of the (surface-confined) imine hydrolysis and the copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition, respectively. For both systems, the kinetic data were spatially visualized in a two-dimensional reactivity map. In the case of the copper(I)-catalysed azide-alkyne 1,3-dipolar cycloaddition, the reaction order (2) was deduced from it

SUOLI SEPOLTI OLOCENICI AL MARGINE APPENNINICO CENTRO-PADANO: ASPETTI GEOARCHEOLOGICI E PALEOAMBIENTALI

The Apennine foothills at the southern limit of the Po plain consist of a belt of coalescent, gravelly, alluvial fans, trending to the north, towards the depocenter of the plain. Their aggradation is generally considered to have been controlled by climate and linked to the glacial periods of the Middle and Upper Pleistocene. At the transition from the Upper Pleistocene to the Holocene, aggradation of most of the alluvial fans stopped and their surface was subject to weathering, which resulted in deep, rubified Alfisols. These developed mainly during the Boreal and Atlantic periods. Beginning in the Sub-Boreal period, fine-textured alluvial deposits buried the distal margin of the alluvial fans and the soils developed on them, constituting a fundamental change in the pedo-sedimentary processes. These deposits consist of fine-sized sediments of overbank facies, organized in fining upward sets and intercalated by buried Entisols, Inceptisols and Vertisols. The accumulation of floodplain sediments on the margin of the alluvial fans, after the prevailing weathering on their top, is related to the climatic change that occured between the end of the Postglacial Hypsithermal period and the beginning of the Neoglacial period. The soils on top of the alluvial fans and in later alluvial deposits show intensive human use and occupation from the Neolithic to the early Bronze Age, and witness a significant change in land exploitation during the Atlantic/Sub-Boreal transition. During the Neolithic (Atlantic period), agricultural practices linked to shifting agriculture had minimal impact on the vegetation mantle and were limited to the plain areas. By contrast, during the Chalcolithic and the early Bronze Age (Sub-Boreal period), a rather different mode of land use was adopted, as the result of the newly introduced transhumant pastoralism. Deforestation through slash and burn techniques was very intense and widespread, extending far beyond the boundary of the plain, deep inside the mountain range, affecting the Po Plain and the adjoining Apennines and Alps. This case study presents an argument for seeing climate change and human activity \u2013 deforestation by fire, agriculture and pastoralism \u2013 as synergic phenomena that shaped the prehistoric landscape

Trends Prediction Using Social Diffusion Models

The importance of the ability of predict trends in social media has been growing rapidly in the past few years with the growing dominance of social media in our everyday's life. Whereas many works focus on the detection of anomalies in networks, there exist little theoretical work on the prediction of the likelihood of anomalous network pattern to globally spread and become "trends". In this work we present an analytic model the social diffusion dynamics of spreading network patterns. Our proposed method is based on information diffusion models, and is capable of predicting future trends based on the analysis of past social interactions between the community's members. We present an analytic lower bound for the probability that emerging trends would successful spread through the network. We demonstrate our model using two comprehensive social datasets - the "Friends and Family" experiment that was held in MIT for over a year, where the complete activity of 140 users was analyzed, and a financial dataset containing the complete activities of over 1.5 million members of the "eToro" social trading community.Comment: 6 Pages + Appendi

OREMP: Ontology Reasoning Engine for Molecular Pathways

The information about molecular processes is shared continuously in the form of runnable pathway collections, and biomedical ontologies provide a semantic context to the majority of those pathways. Recent advances in both fields pave the way for a scalable information integration based on aggregate knowledge repositories, but the lack of overall standard formats impedes this progress. Here we propose a strategy that integrates these resources by means of extended ontologies built on top of a common meta-format. Information sharing, integration and discovery are the primary features provided by the system; additionally, two current field applications of the system are reported