A Gravity Model with Variable Coefficients: The EEC Trade with Third Countries

Gravity models with fixed coefficients have been used to explain the trade flows between countries different in income levels and separated by long distances. It is unrealistic to assume that these models can hold with the same parameters across very heterogeneous countries. This paper proposes and estimates an international trade model with variable coefficients constructed by combining Pöy-hönen's and Linnemann's gravity-based trade models via the expansion method.     

Effect of mollusc eating on human bone strontium levels

Empirical aspects of the movement of strontium through the food chain suggest that the level of bone strontium can be used as an indicator of the percentage of meat in human diet. In general, skeletal remains from agricultural peoples are expected to have high bone strontium levels relative to hunter-gatherers from the same geographical region because plants contain relatively higher amounts of strontium when compared with animal products. The results of the study described in this paper, however, indicate that the inclusion of molluscs as a component of the diet may produce the opposite of the expected strontium values. Burials from an Archaic (c. 2500 BC) hunting-gathering population excavated from Lu^o25, an archaeological site in northern Alabama, USA, exhibit a mean bone strontium level ( atomic absorption; neutron activation) that is higher than the mean level from an agricultural Mississippian (c. AD 1400) population ( atomic absorption; neutron activation) that was buried at the same site. The samples were analysed by two techniques (atomic absorption spectrometry and neutron activation analysis) and the results compared favourably; therefore, the results can be accepted as valid rather than being due to technique error. We propose that the ingestion of molluscs, whose meat is known to contain large amounts of strontium, has produced this reversal from expected results.     

Ludwig Alsdorf 8.8.1904 – 25.3.1978

Indo-Iranian Journal -