and
Ti. j = πr4---
Σ Σ qj
i =1 j =1
(15 15
• Σ Σ q ij ∙ ln
V=1 j =ι
qλ
qi. ∙ q.j )
(i. j ) (5)
A second way to split the matrix into subsets is to sum the subset of 15 Tij-values belonging
to a country i. In this way, one obtains the level of integration for each individual country
labelled as Ti . We get:
for each of the fifteen member states ( i=1,...,15 ). Table 1 provides a numerical example of the
application of all integration measures described above, using imaginary data on collaboration
patterns of three countries.
1 15
Ti = -∙∑ qj■ln
qi. j=1
qj
q,∙ q.j
(6)
TABLE 1 AROUND HERE
Note that the application of this measure is by no means restricted to the analysis of country-
country collaborations. The indicator can be applied to the level of regions in a country (or in
the European union) and to the level of cities in a region (or in a country or in the European
union). Similarly, the indicator can be applied to supranational blocks within the world
system.
4. Results
Data were collected from the Science Citation Index for the period 1993-2000 covering the
the large majority of publications of natural and life sciences. I first selected for each year all
relations between the states of cells in cellular automata (Langton, 1990) and the characterisation of
multi-dimensional NK fitness landscapes in terms of the distribution of local optima (Frenken, 2001).
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