|
|
Type of Document Dissertation Author Dezso, Zoltan Author's Email Address zdezso@nd.edu URN etd-08312005-210328 Title The Topology and Dynamics of Complex Networks Degree Doctor of Philosophy Department Physics Advisory Committee
Advisor Name Title Michael Gekhtman Committee Chair Barabási, Albert-László Committee Member Jones, Gerald Committee Member Kolda, Christopher Committee Member Newman, Kathie Committee Member Keywords
- complex networks
- virus spreading
- information acces
- protein complexes
Date of Defense 2005-08-25 Availability unrestricted Abstract We start with a brief introduction about the topological properties ofreal networks. Most real networks are scale-free, being characterized by
a power-law degree distribution. The scale-free nature of real networks leads
to unexpected properties such as the
vanishing epidemic threshold.
Traditional methods aiming to reduce the
spreading rate of viruses cannot succeed on eradicating the epidemic on a
scale-free network.
We demonstrate that policies that discriminate between the nodes, curing mostly
the highly connected nodes, can restore a finite epidemic threshold and potentially
eradicate the virus. We find that the more biased a policy is towards the hubs, the
more chance it has to bring the epidemic threshold above the virus' spreading rate.
We continue by studying a large Web portal as a model system for a
rapidly evolving network. We find that the visitation pattern of a news document decays
as a power law, in contrast with the exponential prediction provided by simple models
of site visitation. This is rooted in the inhomogeneous nature of the browsing
pattern characterizing individual users: the time interval between consecutive
visits by the same user to the site follows a power law distribution, in contrast
with the exponential expected for Poisson processes. We show that the exponent
characterizing the individual user's browsing patterns determines the power-law
decay in a document's visitation.
Finally, we turn our attention to biological networks and demonstrate
quantitatively that protein complexes
in the yeast, Saccharomyces cerevisiae, are comprised of a
core in which subunits are highly coexpressed, display the
same deletion phenotype (essential or non-essential) and share
identical functional classification and cellular localization.
The results allow us to define the deletion phenotype and cellular
task of most known complexes, and to identify with high confidence
the biochemical role of hundreds of proteins with yet
unassigned functionality.
Files
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access DezsoZ082005.pdf 959.70 Kb 00:04:26 00:02:17 00:01:59 00:00:59 00:00:05