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Seminars & Colloquia

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Colloquium dan
Daniel B. Larremore
Omidyar Fellow
Santa Fe Institute
Thursday, November 12,2015

Title:Networks and the evolution of malaria's virulence in humans and apes

Abstract:  Despite extensive research and public health efforts, there remain hundreds of millions of malaria cases annually, causing over half a million deaths, mostly children. Key to malaria's ongoing transmission is the fact that humans develop only a weak immunity, stemming from the parasite’s evasion of the immune system by sequential expression of camouflage-like proteins on the surface of infected red blood cells. The genetic variation within the camouflage-encoding var genes is sufficiently high dimensional that immunity to a single camouflage variant doesn't hinder future infections. What’s more, each parasite genome contains ~60 different var genes, which rapidly recombine, precluding the use of traditional phylogenetic techniques. I will present a series of investigations to understand the key mechanisms and constraints underlying the ongoing evolution of var genes.

We first developed a framework capable of mapping rapidly recombining genes to networks in which evolutionary constraints are revealed in large-scale network structures. Applying this approach to multiple genomes, we identified the parts of the camouflage proteins that evolve differently than others. To improve the quality of network community detection, we developed a bipartite stochastic block model using maximum likelihood-based inference, and then applied it to an expanded data set including var genes from ape-infecting malaria parasites. This revealed the deep origins of the malaria parasite's current immune evasion strategy, which evolved tens of millions of years ago in an ancient ancestor of extant malaria species. This frames the current adaptive struggle in humans in a broader evolutionary context, with implications for parasite population genetics as malaria prevention efforts shift toward elimination. It also begs for the continued development of principled network-based mathematical models to answer open biological questions.

Sun, Q
Qiyu Sun
Professor of Mathematics
at University of Central Florida
Thursday, November 5, 2015

Title:Wiener's Lemma for matrices and its applications to sampling

Abstract:  The classical Wiener's lemma states that a periodic function with an absolutely convergent Fourier series, which vanishes nowhere on the real line, has Fourier series of  its reciprocal being absolutely convergent. In this talk, I will discuss Wiener's lemma to localized matrices,  and its applications to sampling theory for spatially distributed system.

joe skufca
Joseph Skufca
Professor and Chair
Thursday, October 22, 2015
SC 356

Title:Moving Neighborhood Networks: The dynamic topology of communicating agent

Abstract: This talk will consider the dynamic "social" network that arises when mobile agents are able to communicate only locally.  We consider a number of different models of such behavior and demonstrate the natural applicability in such settings as coordinated behaviors and epidemiology.  By use a model of coupled chaotic oscillators as a "probe" to better understand the effect of the spatial dynamics as in impacts the underlying communication characteristics of the resultant social network.