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On Mon, 23 Jul 2001, Valdis wrote:
> Can we stop the AIDS epidemic by focusing on the high degree Hubs in the
> network?

I agree with the others who have followed up.  We must be careful not to
let the constraints or focus of a model overly constrain our possible
avenues of attack.

I hope this isn't inappropriate, but off the cuff I see value in a
physical analogy of networks.  I have no URLs to cite, sadly.

Networks - corresponds to pipes, interconnected between nodes.
Infection - corresponds to fluid transported by pipes.

Fluid flow volume over time through a node is trivially as follows:

        cross-section X velocity X density

where
        cross-section = proportionate to connectivity
        velocity = proportionate to frequency of transmission
        density = proprotionate to effectiveness of transmission

The model suggests three points of attack to stem flow, aside from the
elimination of nodes in the network.

        minimize cross-section: high connectivity hubs
        minimize velocity: numerically common vectors
        minimize density: high risk infectivity vectors

Prevention efforts should attack all three, depending on which is most
effective.  There is no a priori one best attack mode from this model.
From the model, one should be able to demonstrate the effectiveness of
each method of attack individually, but a combined picture gives a more
accurate assessment of the situation.

Jim Lai