Department of

# Mathematics

Seminar Calendar
for Mathematical Biology events the year of Friday, January 1, 2016.

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events for the
events containing

Questions regarding events or the calendar should be directed to Tori Corkery.
    December 2015           January 2016          February 2016
Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa   Su Mo Tu We Th Fr Sa
1  2  3  4  5                   1  2       1  2  3  4  5  6
6  7  8  9 10 11 12    3  4  5  6  7  8  9    7  8  9 10 11 12 13
13 14 15 16 17 18 19   10 11 12 13 14 15 16   14 15 16 17 18 19 20
20 21 22 23 24 25 26   17 18 19 20 21 22 23   21 22 23 24 25 26 27
27 28 29 30 31         24 25 26 27 28 29 30   28 29
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Thursday, March 10, 2016

1:00 pm in 345 Altgeld Hall,Thursday, March 10, 2016

#### A stochastic model of eye lens growth: the case of a mouse

###### Hrvoje Sikic (Washington U. School of Medicine)

Abstract: A lens focuses light on the retina. It needs to be built with a precise shape and size. We develop a stochastic model relating the rates of cell proliferation and death in various regions of the lens epithelium to deposition of fiber cells and radial lens growth. Epithelial population dynamics were modeled as a branching process with emigration and immigration between proliferative zones. We show that a stochastic engine can produce the smooth and precise growth necessary for lens function.

Thursday, September 22, 2016

1:00 pm in 347 Altgeld Hall,Thursday, September 22, 2016

#### Tiny Giants - Mathematics Looks at Zooplankton

###### Peter Hinow (Mathematics, University of Wisconsin, Milwaukee)

Abstract: Zooplankton is an immensely numerous and diverse group of organisms occupying every corner of the oceans, seas and freshwater bodies on the planet. They form a crucial link between autotrophic phytoplankton and higher trophic levels such as crustaceans, molluscs, sh, and marine mammals. Changing environmental conditions such as water temperatures, salinities and pH values currently create monumental challenges to their well-being. A signi cant subgroup of zooplankton are crustaceans of sizes between 1 and 10 mm. Despite their small size they have extremely acute senses that allow them to navigate their surroundings, escape predators, nd food and mate. In a series of joint works with Rudi Strickler (Department of Biological Sciences, University of Wisconsin - Milwaukee) we have investigated various behaviors of crustacean zooplankton. These include the visualization of the feeding current of the calanoid copepod Leptodiaptomus sicilis, the introduction of the \ecological temperature" as a descriptor of the swimming behavior of water eas Daphnia pulicaria and the communication by sex pheromones in copepods. The tools required for the studies stem from optics, ecology, neuroanatomy, computational uid dynamics, and computational neuroscience.

Thursday, October 6, 2016

1:00 pm in 347 Altgeld Hall,Thursday, October 6, 2016

#### The Combinatorics of RNA Branching

###### Christine Heitsch (Mathematics, Georgia Tech)

Abstract: Understanding the folding of RNA sequences into three-dimensional structures is one of the fundamental challenges in molecular biology. For example, the branching of an RNA secondary structure is an important molecular characteristic yet difficult to predict correctly, especially for sequences on the scale of viral genomes. However, results from enumerative, probabilistic, analytic, and geometric combinatorics yield insights into RNA structure formation, and suggest new directions in viral capsid assembly.

Thursday, October 27, 2016

1:00 pm in 347 Altgeld Hall,Thursday, October 27, 2016

#### Convexity in Tree Spaces

###### Bo Lin   [email] (UC Berkeley)

Abstract: We study the geometry of metrics and convexity structures on the space of phylogenetic trees, which is here realized as the tropical linear space of all ultrametrics. The ${\rm CAT}(0)$-metric of Billera-Holmes-Vogtman arises from the theory of orthant spaces. While its geodesics can be computed by the Owen-Provan algorithm, geodesic triangles are complicated. We show that the dimension of such a triangle can be arbitrarily high. Tropical convexity and the tropical metric behave better. They exhibit properties desirable for geometric statistics, such as geodesics of small depth. This is a joint work with Bernd Sturmfels, Xiaoxian Tang and Ruriko Yoshida.