Optically-stimulated luminescence profiling and dating of historic agricultural terraces in Catalonia (Spain)

Dating agricultural terraces is a notoriously difficult problem for archaeologists. The frequent occurrence of residual material in terrace soils and the potential for post-depositional disturbance mean that conventional artefactual and lab-based dating methods often provide unreliable dates. In this paper we present a new technique using luminescence field profiling coupled with OSL dating to produce complete (relative) sequences of dates for sedimentary stratigraphies associated with agricultural terraces and earthworks. The method is demonstrated through a series of case-studies in western Catalonia, Spain, in which we reconstruct the formation sequence of earthwork features from the Middle Ages through to the present day. OSL profiling at the time of archaeological survey and excavation permitted spatially and temporally resolved sediment ‘chronologies’ to be generated, and provides the means to interpret the environmental and cultural archives contained in each. The case-studies presented here show that luminescence approaches are a valuable tool to reconstruct landscape histories

Supply constraints on rebound effects of increased energy efficiency : negative multiplier and disinvestment effects

Policies that aim to use increased energy efficiency to reduce energy use may not achieve the desired results due to the likelihood of rebound effects. Research from our current ESRC-funded project on this topic was presented in an article in the last issue of Fraser Economic Commentary titled, ‘Energy Efficiency and the rebound effect’ (Turner, 2009a). As explained there, the rebound effect occurs when an energy efficiency improvement causes a decrease in the effective or implicit price of energy as an input to production (or consumption) – i.e. the cost of energy required per unit of activity falls as efficiency improves.1 Moreover, if there is local production/distribution of energy (or energy services) the reduction in demand for energy as efficiency improves will put downward pressure on the actual (local) energy price

The coevolution of toxin and antitoxin genes drives the dynamics of bacterial addiction complexes and intragenomic conflict

Bacterial genomes commonly contain ‘addiction’ gene complexes that code for both a toxin and a corresponding antitoxin. As long as both genes are expressed, cells carrying the complex can remain healthy. However, loss of the complex (including segregational loss in daughter cells) can entail death of the cell. We develop a theoretical model to explore a number of evolutionary puzzles posed by toxin–antitoxin (TA) population biology. We first extend earlier results demonstrating that TA complexes can spread on plasmids, as an adaptation to plasmid competition in spatially structured environments, and highlight the role of kin selection. We then considered the emergence of TA complexes on plasmids from previously unlinked toxin and antitoxin genes. We find that one of these traits must offer at least initially a direct advantage in some but not all environments encountered by the evolving plasmid population. Finally, our study predicts non-transitive ‘rock-paper-scissors’ dynamics to be a feature of intragenomic conflict mediated by TA complexes. Intragenomic conflict could be sufficient to select deleterious genes on chromosomes and helps to explain the previously perplexing observation that many TA genes are found on bacterial chromosomes

Changes and continuities in a Mediterranean landscape : a new interdisciplinary approach to understanding historic character in western Catalonia

This work was supported by Ministerio de Economía y Competitividad, Spain [grant number MINECO HAR2012-35022].To understand why historic landscapes changed in the past researchers need to identify when and where changes took place, but in rural landscapes, the origins and development of many historic elements including field systems, roads, terraces and other earthworks remain poorly understood. This paper outlines a practical interdisciplinary method using GIS-based historic landscape characterisation (HLC) to integrate data from different sources and model how historic character varies in space. It pilots an innovative approach using luminescence profiling and dating that can underpin the HLC with significantly improved knowledge of historic processes of change. We focus on four case studies of terraced agricultural landscapes in western Catalonia and demonstrate for the first time that existing terrace systems often have medieval or early modern origins.Publisher PDFPeer reviewe

Temporary Silage Storage

The following information is intended as a supplement to the attached publication entitled Temporary Silage Storage Systems published by the Purdue University Cooperative Extension Service

Paysages et relations : archéologie, géographie, archéogéographie

RésuméSam Turner, Paysages et relations : archéologie, géographie, archéogéographieDans cette brève contribution l’auteur se propose d’observer comment l’archéologie des paysages a évolué ces dernières années. Ayant été lui-même sollicité pour mettre au point une méthode appelée, au Royaume-Uni, « caractérisation des paysages historiques » (Historic Landscape Characterisation : HLC), il observe que cette méthode gagnerait à s’engager plus loin dans les possibilités théoriques qu’offre l’archéogéographie. Par voie de conséquence, une nouvelle opportunité s’ouvrirait aux archéologues du paysage de replacer leur discipline au cœur des débats sur la société et l’environnement. Ce qui marque un véritable changement par rapport aux décennies précédentes.AbstractSam Turner, Landscapes and relationships: archaeology, geography, archaeogeographyIn this short article the author examines recent developments in landscape archaeology. Having been involved in developing the method known as “Historic Landscape Characterisation” (HLC) in the UK, he argues that the theoretical perspectives of archaeogeography have much to offer modern landscape archaeologies. As a consequence of such engagements, new opportunities are opening for archaeologists to put their discipline back at the heart of debates about the environment and society in the present and the future. This marks a notable change in comparison to earlier decades

Titanium milling strategies.

This thesis explores the subject of titanium milling and identifies the need for development of titanium milling strategies to address the key process limitations of chatter and tool wear. These subjects are typically studied in isolation and little work has previously been undertaken on titanium milling dynamics. Titanium is often perceived as difficult to machine as the very properties such as high strength at high temperature and low thermal conductivity that make it an attractive engineering material can cause rapid tool wear and limit process parameters. Titanium alloys are increasingly popular within the aerospace industry due to the high strength to weight ratios and titanium and carbon fibre composites have replaced many steel and aluminium components within aerostructures. Titanium is still seen by many as expensive to process and there is not the same degree of understanding and process optimisation within the machining industry as there is for aluminium and steel alloys. The literature review considers both advances in titanium tool wear mechanisms and research into machining dynamics. From the literature review three research hypotheses are developed around the knowledge gaps pertaining to titanium milling stability and process optimisation. The limitations on milling performance and productivity are considered and three areas are identified where the research could be advanced to improve titanium milling productivity through manipulation of parameters and tool geometry, these areas are pocketing strategies, special tooling geometries and process damping. A method for controlling radial immersion for pocketing strategies is developed and it is proven that through control of parameters and toolpaths that tool life and productivity can be optimised and controlled. A study is then undertaken into the performance and modelling of variable helix end mills to explore the hypothesis that the tools will outperform standard and variable pitch cutters and that the performance can be modelled. As part of the validation process an analysis of the linearity of machine tool dynamics is undertaken and it is demonstrated that under speed and load, spindle and machine tool frequency responses can differ from those measured in the static condition. The final part of the research investigates process damping performance and sensitivity to cutting tool geometry and feed rates. A method for evaluating process damping performance is developed and through optimisation of tool geometry and feed per tooth increases in productivity up to 17 fold are demonstrated. A method is then presented for tuning machine tool dynamics to optimise process damping performance and stabilise sub optimum tooling and machine tools. The three core strands of the thesis are brought together and demonstrated in an aerospace case study. Through application of the techniques developed in the thesis a titanium aerostructural component is machined at the same rates as an equivalent steel component and at less than 50% of the planned titanium milling process time

Application of thin-walled dynamics for advanced manufacturing solutions

This is a review paper, exampled with several typical applications of thin-walled dynamics for advanced manufacturing solutions. Theoretically, the mechanical and dynamical characteristics of thin-walled structures are discussed. Following this, basic principles of dynamic solutions, including dynamic fixture design for thin-walled structures as well as dynamic treatments of the machining system, are summarized. Several typical applications of these principles for practical manufacturing are illustrated and analyzed, followed with conclusions for the whole paper

Optically stimulated luminescence profiling and dating of earthworks : the creation and development of prehistoric field boundaries at Bosigran, Cornwall

This work has received funding from the FWO (Research Foundation—Flanders) and the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement (665501).Accurately dating the creation and development of earthwork features is a long-standing problem for archaeologists. This article presents results from Bosigran (Cornwall, UK), where boundary banks believed to be prehistoric in origin are assessed using optically stimulated luminescence profiling and dating (OSL-PD). The results provide secure construction dates for different boundaries in the Bronze and Iron Ages, as well as chronologies for their early medieval and later development. The research demonstrates not only the prehistoric origins of these distinctive Cornish field systems, but also a practical and cost-effective methodology suitable for dating earthworks around the world.Publisher PDFPeer reviewe