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A Faster Algorithm for Betweenness Centrality
 Journal of Mathematical Sociology
, 2001
"... The betweenness centrality index is essential in the analysis of social networks, but costly to compute. Currently, the fastest known algorithms require #(n ) time and #(n ) space, where n is the number of actors in the network. ..."
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Cited by 500 (5 self)
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The betweenness centrality index is essential in the analysis of social networks, but costly to compute. Currently, the fastest known algorithms require #(n ) time and #(n ) space, where n is the number of actors in the network.
Centrality estimation in large networks
 INTL. JOURNAL OF BIFURCATION AND CHAOS, SPECIAL ISSUE ON COMPLEX NETWORKS’ STRUCTURE AND DYNAMICS
, 2007
"... Centrality indices are an essential concept in network analysis. For those based on shortestpath distances the computation is at least quadratic in the number of nodes, since it usually involves solving the singlesource shortestpaths (SSSP) problem from every node. Therefore, exact computation is ..."
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Cited by 51 (0 self)
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Centrality indices are an essential concept in network analysis. For those based on shortestpath distances the computation is at least quadratic in the number of nodes, since it usually involves solving the singlesource shortestpaths (SSSP) problem from every node. Therefore, exact computation is infeasible for many large networks of interest today. Centrality scores can be estimated, however, from a limited number of SSSP computations. We present results from an experimental study of the quality of such estimates under various selection strategies for the source vertices.
Faster Evaluation of ShortestPath Based Centrality Indices
, 2000
"... Centrality indices are an important tool in network analysis, and many of them are derived from the set of all shortest paths of the underlying graph. The socalled betweenness centrality index is essential for the analysis of social networks, but most costly to compute. Currently, the fastest known ..."
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Cited by 2 (0 self)
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Centrality indices are an important tool in network analysis, and many of them are derived from the set of all shortest paths of the underlying graph. The socalled betweenness centrality index is essential for the analysis of social networks, but most costly to compute. Currently, the fastest known algorithms require Theta(n³) time and Theta(n²) space, where n is the number of vertices. Motivated by the fastgrowing need to compute centrality indices on large, yet very sparse, networks, new algorithms for betweenness are introduced in this paper. They require O(n + m) space and run in O(n(m + n)) or O(n(m + n log n)) time on unweighted or weighted graphs, respectively, where m is the number of edges. Since these algorithms simply augment singlesource shortestpaths computations, all standard centrality indices based on shortest paths can now be computed uniformly in one framework. Experimental evidence is provided that this substantially increases the range of network...
The effectiveness of needle exchange programs: a review of the science and policy. AIDScience 1:1–33
, 2001
"... eedle exchange programs (NEPs) permit injection drug users (IDUs) to exchange potentially contaminated syringes for sterile ones, with the aim of decreasing the circulation of contaminated injection equipment and reducing the spread of bloodborne pathogens in the community. Since the first NEP was ..."
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Cited by 1 (0 self)
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eedle exchange programs (NEPs) permit injection drug users (IDUs) to exchange potentially contaminated syringes for sterile ones, with the aim of decreasing the circulation of contaminated injection equipment and reducing the spread of bloodborne pathogens in the community. Since the first NEP was introduced in Amsterdam in 1984, at least 46 regions, countries, and territories reported having at least one NEP by December 2000. Surprisingly, only onethird of countries where HIV has been reported among IDUs and only 40 % of countries where injection drug use is known to occur have introduced at least one NEP. There are also considerable variations in NEP availability and coverage within and between countries, and sometimes within states or cities. This review discusses the history, science, and politics surrounding the implementation and evaluation of NEPs in both developed and developing countries, and suggests alternative mechanisms to increase coverage of sterile syringes among IDUs. We also suggest areas for further research to guide future attempts at interventions that aim to reduce the global spread of bloodborne infections.