Scientific cities

Most scientific work is done in cities of differing sizes. One element of a national science policy may be deciding which cities are either over- or under-represented in terms of scientific concentration. Up till now, most decisions on this question have been political or economic in nature. However, it is possible to measure one aspect of this concentration so as to allow decision-makers a more rational basis for their determinations. The data used were the number of primary authors publishing in approximately 3700 major scientific journals. Because the scientific concentration can vary greatly with the size of city, the latter were divided into five categories. The cities which led each of these population classifications were Washington, Munich, Prague, Madison (Wisconsin), and Cambridge (Massachusetts). The data can also be used as a measure of the centralization of science in different countries. Of the eight major scientific nations, the USSR and Japan have the highest degree of centralization. However, if the effect on the degree of the major scientific city in each country is removed, Canada has the highest centralization. These conclusions may have ramifications for national science policies.     

Design of minimum sensitivity multiple loop feedback bandpass active filters

A method is described for determining multiple loop feedback topologies which yield minimum sensitivities for symmetrical, all-pole bandpass filters. The procedure begins with a follow-the-leader feedback (FLF) topology and additional feedback loops are constructed until minimum sensitivity is achieved. Filters comprised of identical second-order sections and non-identical sections, respectively, are considered.     

Radiocarbon geophysics

Radiocarbon dating is, and remains, one of the most powerful methods of dating archaeological artefacts. Initially, it was assumed that the carbon-14 content of atmospheric carbon dioxide had remained constant, but latterly it has been shown that this assumption is not valid. It has now proved possible, mainly by correlation with tree-growth rings, to measure historic fluctuations in carbon-14 content and to make the necessary corrections—of up to one thousand years—to the conventionally calculated dates.