## Colloquium and Seminar Schedule

Fall 2016This is the schedule of colloquia and seminars inthe Department of Mathematics and Computer Science for the Fall semester, 2016.

## November 2016

"Mathematical Phylogenetics"

Speakers: Yu (Phoebe) Cai '17 and Casey Coffey '17

Date: Thursday, November 3

Time: 4:45 PM

Location: Napier 201

Refreshmentswill be served at 4:30.

Abstract:

Topic I: Constructing gene trees from DNA data and then building the species tree from the gene trees is traditionally how species trees are estimated. One of our projects follows this traditional way of using gene trees to construct a species tree by our own computer programs. By theorems for gene trees with four or less taxa, the dominant gene trees are always the same as the species trees. So our first project will break up all the gene trees to all possible quartets and pick the one that appears most often in the three types of quartets.

Topic II: Under the coalescent model we construct species trees with their branch lengths directly from the DNA data itself bypassing the step involving gene trees. Our other project follows this such that we can directly predict the species tree from DNA data. Using the coalescent model we estimate distances on the species tree between two taxa and use the distances to build species trees. This distance formula we found is very similar to the popular Jukes-Cantor distance model but includes an additional constant term, which accounts for the mutation rate and effective population size. By using both formulas in the analysis of milkweed data we can compare and observe the way effective population size effects the construction of species trees.

## December 2016

Applications of Knot Theory: Using Knot Theory to Unravel Biochemistry Mysteries

Speaker: Professor Candice Price, University of San Diego

Date: Friday, December 2

Time: 4:15 PM

Location: Sanford Room

Refreshmentswill be served at 4:00.

Abstract:

Although knots have been used since the dawn of humanity, the mathematical study of knots is only a little over 100 years old. Not only has knot theory grown theoretically, the fields of physics, chemistry and molecular biology have provided many applications of mathematical knots. In this talk, I provide an overview of some connections between knot theory and DNA-protein interaction, outlining specifics of the biological mechanisms of DNA replication while providing an overview of related knot invariants

## Past Colloquia Series

Spring 2016 Fall 2015 Spring 2015 Fall 2014 Spring 2014 Fall 2013

Spring 2013 Fall 2012 Spring 2012 Fall 2011 Spring 2011

If you have interest in giving a talk or know of someone who does,

please contact Prof. Yan Hao at hao@hws.edu