A Zero‐One Programming Model for Contiguous Land Acquisition

The land acquisition problem is a spatial partitioning problem that involves selecting multiple parcels to be acquired for a particular land use. Three selection criteria are considered: total cost, total area, and spatial contiguity. Achieving contiguity or connectivity has been problematic in previous exact methods for land acquisition. Here we present a new zero‐one programming model that enforces necessary and sufficient conditions for achieving contiguity in discrete cell landscapes, independent of other spatial attributes such as compactness. Computational experience with several demonstration problems is reported, and results and extensions are discussed.     

The limits of engagement: British foreign policy and the crisis in Zimbabwe

This article examines how the British government has responded to Zimbabwe’s ongoing crisis. This case raises several wider issues for British foreign policy, most notably the question of how much leverage London can exercise on the international scene in general, and over relatively small and weak states like Zimbabwe in particular. Zimbabwe’s crisis also raises profound questions about the appropriate balance between bilateral and multilateral policies, and between engaging in public criticism and conducting so–called ‘quiet diplomacy’. While bilateralism clearly has not worked, multilateralism has revealed its own frustrations, especially given the reluctance of many African elites within a number of organizations to criticize President Mugabe’s policies. This reluctance threatens to unravel the British Labour government’s stated objectives in Africa while at the same time raising important doubts over the credibility of the New Partnership for Africa’s Development (NEPAD), and whether an ‘Africa moment’ can be discerned in the manner articulated by prime minister Tony Blair.     

Tracing the source of Late Neolithic Spondylus shell ornaments by stable isotope geochemistry and cathodoluminescence microscopy

Determination of the source of Spondylus objects is essential for the interpretation of Late Neolithic exchange systems and the social role of shell ornaments. We performed stable isotope analysis combined with cathodoluminescence microscopy study on ornaments (beads, bracelets) made of Spondylus shells excavated at the Aszód-Papi földek archaeological site in Hungary, to define their origin. For comparison Spondylus finds from Neolithic sites of Greece, modern Spondylus shells from the Aegean and the Adriatic, as well as fossil Spondylus and Ostrea shells from the Carpathian Basin were also examined. Oxygen isotope composition of Spondylus finds from Aszód ranges between ?1.9 and 2.1‰ and overlaps with the oxygen isotope range of shell objects from other Neolithic sites. Modern Spondylus shells from the Aegean and the Adriatic show overlapping δ¹⁸O values with one another and with the Neolithic objects; while recent shells of the Black Sea clearly are separate isotopically from the Mediterranean ones and most of archaeological artefacts. Spondylus shells from the Aszód site have Mediterranean origin; their source can be the Aegean or the Adriatic. Based on a former strontium isotope study the use of fossil Spondylus shells is excluded as raw material used for ornaments, however, in recent years the use of fossil shells was reintroduced. The shell ornaments from Aszód-Papi földek and the fossil oyster shells collected from the Carpathian Basin exhibit some overlapping oxygen isotope values; however, cathodoluminescence microscopy indicates that the Spondylus objects retained their original aragonite material. Diagenetic calcite, which occurs typically in the fossil shells, was not detected in the ornaments suggesting that the studied objects were made of recent shells. Calcitic parts observed in some Spondylus objects are not related to fossilisation.