Figure 4. Knowledge diffusion proxy results.

(A) The Top 4 producer cities in the USA in 2009 and their Top 10 consumers from knowledge diffusion proxy algorithm in 1990 – 2009. (B) The Top 4 producer cities in the European Union 27 countries as well as Switzerland and Norway in 2009 and their Top 10 consumers from knowledge diffusion proxy algorithm in 1990 – 2009. When a producer city becomes a consumer in some year, a grey strip is marked in that year. For each producer city in (A) and (B), the major consumers of the first producer city m in 20 years are plotted as a function of time from 1990 to 2009. The size of the bubble in position (Y, c) is also proportional to the counter g_m,c(Y) in that year. The consumer cities for each producer are ordered according to the total number of counters in 20 years, i.e., .