THE FUNDAMENTAL RELATIONSHIP BETWEEN ANCIENT DIET AND THE INORGANIC CONSTITUENTS OF BONE AS DERIVED FROM FEEDING EXPERIMENTS

The levels of ten elements (phosphorus, calcium, magnesium, strontium, barium, potassium, sodium, zinc, iron, and aluminium) have been measured in the femurs and humeri of laboratory rats grown on test diets as a model for palaeodietary studies of excavated human skeletons. High levels of dietary fibre correlate with lower Ca and higher Sr and Ba in the bone. High values of the dietary Sr/Ca ratio correlate with high Sr levels in the bone. High levels of dietary protein correlate with lower Sr and higher Zn. High values of the ratio Ba/Ca and lower levels of Fe correlate with higher levels of Ba. Because bone levels typically are controlled by several dietary components, variation of the levels of a given element in the diet does not necessarily translate into analogous variations in bone. Only K and Fe in bone correlate highly with their levels in diet. The failure of bone Sr, Ba, and Zn to correlate positively with dietary levels is fully explicable in terms of their interdependence on other dietary components, such as Ca, P, Fe, protein, and fibre.     

Alternative explanations of the dependence of the density of centers on the density of population

ABSTRACT. The paper is devoted to modeling the relationship between the density of service centers and the density of population (or on the density of demand). Several models lead to an exponential function with the exponent equal to ⅔. For a number of real systems of centers, the power is considerably different from ⅔ (more often it is nearer to 1). I describe a series of models that explain this difference.     

Selected Characteristics of Soviet Foreign Trade and Implications for the Foreign Trade of the Commonwealth of Independent States

This paper provides observations on recent patterns of the Soviet Union's foreign trade in the context of factor endowment trade theory and two models drawn from the new trade theory. Empirical analysis indicates that recent Soviet foreign trade was not based on differing factor intensities between Soviet goods and the those of the rest of the world. Instead, the recent geography of Soviet foreign trade suggests that it conformed more to the trade in differentiated products expected under the new trade theory. These results suggest that Soviet foreign trade had developed in such a way that, at least with respect to merchandise trade, the Commonwealth of Independent States (CIS) has a strong potential for fairly rapid integration within the group of industrial countries.     

The Encoding-Error Model of Pathway Completion without Vision

We present a model that accounts for errors in short-cutting to complete a triangular pathway by individuals deprived of visual input. The model assumes that systematic error arises from components of navigation concerned with encoding an internal representation of the pathway, rather than the computation of a homeward trajectory or motor output per se. Subjects' tendency to compress the range of actually produced turns and distances, in comparison to the range of correct values, is attributed to regression toward the mean of encoded values during encoding of segments and turns, in the face of uncertainty about the actual values. Individual-subject variations are attributed to differences in the encoding-function parameters, not to variations in the processes themselves. The model provides excellent accounts of data obtained with triangular pathways but fares less well when pathway complexity increases, at which point errors do not appear to be solely attributable to encoding processes. The sources of error identified by the model are likely to play a role in navigation more generally.     

Ideas or Interests: Privacy in Electronic Communications

This article examines why the idea of privacy failed to structure policymaking in the case of the Electronic Communications Privacy Act (ECPA). Although the relatively quick passage of ECPA might appear to be a case of the politics of ideas, the model of interest group politics more simply explains policy making. The analysis of this case suggests several factors as important in establishing the conditions under which a politics of ideas will be realized.