Palaeoenvironments, the archaeological record and cereal pollen detection at Clickimin, Shetland, Scotland

The Loch of Clickimin, Shetland, is well known for its broch and associated monuments supposedly of the Bronze and Iron Ages, although the former date is disputed. Pollen, diatom and sedimentological investigations permit fresh insights into the landscape and economic impacts of those who constructed the monuments, reveal that the environs of the site experienced environmental change from Neolithic times onward and provide the first Holocene radiocarbon dates from the immediate locality. The broch-building period witnessed a continuation of pre-existing pastoral husbandry for which heather burning may have exacerbated the natural spread of blanket peat. Initially, no evidence was adduced for local arable activity in the present investigation, and this was thought to be consistent possibly with the low numbers of excavated querns and the absence of cereal macrofossil finds when compared with other Shetland broch sites. The application of ‘rapid scanning’ techniques, however, led to the discovery of a consistent cereal-type pollen representation from Bronze Age times onwards. The discrepancies between the palaeoenvironmental evidence and the environmental and palaeoeconomic inferences made by the excavator of the site are explored. Evidence is presented that both supports and contradicts previous assumptions surrounding an important archaeological site.     

18th- and 19th-century shipyards at the south-east entrance to the West India Docks, London

Archaeological fieldwork in 1997 on the Isle of Dogs, at the south-east entrance to the West India Docks, recovered evidence of 17th- to 19th-century shipyards, associated activities and foreign trade. Reused timbers may be the remains of the 17th-century Rolt's yard. Reclamation along the natural inlet was accompanied by the construction of a timber dry dock probably in the late 18th century. This soon fell out of use and was filled in with the construction of new dry docks to the south in 1806 by Thomas Pitcher. Much of the debris dating to the first half of the 19th century from ship repairing and building and from a range of ancillary crafts, together with ceramics from Iberia and the Far East, probably came from Pitcher's yard.     

An experimental study of nitrogen flux in llamas: is N preferentially excreted?

Nitrogen isotope analysis is now commonly used to investigate the diets, and to a lesser extent, the environments of ancient populations. These studies assume that mammals are predictably enriched in ¹⁵N over their food, and concomitantly, that ¹⁵N becomes increasingly concentrated as one moves up the food chain. The literature commonly states that this ¹⁵N-enrichment of mammalian tissues is due to preferential excretion of light nitrogen (¹⁴N), but there are few data to support this assertion. To address the gap, we conducted two nitrogen flux trials in which four llamas (Lama glama) were fed high- and low-protein diets. The ratios of fecal nitrogen loss to urinary nitrogen loss were 0.30 and 0.88 on the high- and low-protein diets respectively. Feces were enriched in ¹⁵N by approximately +3‰ on both diets, whereas urinary nitrogen was depleted in ¹⁵N (−2.1‰) on the low-protein diet, but not significantly different from intake δ¹⁵N on the high-protein diet. Most importantly, there was no statistically significant difference between dietary and total excreta δ¹⁵N on either diet. Given these data and theoretical considerations, we argue that the nitrogen influx and efflux of adult mammals at steady state should be isotopically commensurate. However, during growth, diet change, thermal or nutritional stress, animals may not be at steady state and fractionation between intake and excreta δ¹⁵N may occur.     

Surviving in a Competitive Spatial Market: The Threshold Capture Model

Many facility location decision models ignore the fact that for a facility to survive it needs a minimum demand level to cover costs. In this paper we present a decision model for a firm that wishes to enter a spatial market where there are several competitors already located. This market is such that for each outlet there is a demand threshold level that has to be achieved in order to survive. The firm wishes to know where to locate its outlets so as to maximize its market share taking into account the threshold level. It may happen that due to this new entrance, some competitors will not be able to meet the threshold and therefore will disappear. A formulation is presented together with a heuristic solution method and computational experience.