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Senior Comps 2010

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Fractal Dimension and Cell Colony Boundaries

Gabriela Rodriguez

The boundary of a colony of cells growing in vitro can be quite rough and irregular. Its fractal dimension is typically between 1 and 2. Fractal dimension and other critical exponents have proven useful in classifying colony growth dynamics.

This talk will focus on the theoretical concept of fractal dimension and its practical approximation using the box-counting method. The method will be illustrated by computing the fractal dimension of the Koch curve and by estimating the fractal dimension of a tumor boundary. This talk will be accessible to anyone who has a background in calculus.

 

Exploring the Property of Intrinsic Knottedness in Spatial Graphs

 Jonathan Miller

A graph is said to be intrinsically knotted (IK) if every spatial embedding of it in 3-dimensional space contains a nontrivial knotted cycle. It's known that there are finitely many such minor-minimal graphs (that is, one in which no IK “sub-graph” exists) - but because establishing this property is difficult and requires a great deal of ingenuity, a full characterization of this set remains an important open problem in this field. In this talk, I’ll be presenting some methods I employed as part of a research team with Prof. Naimi of the Math Department. I'll discuss some new IK graphs we discovered, as well as the tools we developed to approach this problem. While it's helpful to have some background in Graph Theory, any student with an interest in graphs should be able to follow along.

 

Crystallographic Point Groups

  Elizabeth Mojarro

Crystals are beautiful and fascinating substances that have captivated the attention of the general public and mathematicians alike for hundreds of years.  Their unique characteristics have been the subject of continual study and led to the development of crystallography (i.e. the study of the structures of crystals).  Group theory is an essential tool used in classifying these structures. In particular, crystals can be classified into 32 distinct crystallographic point groups, which are crystallographic groups that leave a common point fixed.  I will discuss the role of Group Theory in crystallography and its role in determining the point group a crystal belongs to.

 

The Game of Nim and Its Winning Strategy

 Jason Jebbia

Do games and puzzles involving numbers and strategy interest you?  The game of Nim is just that kind of game.  It has been played for hundreds of years under different names. Nim is a simple, mathematical game in which two-players take turns removing objects from piles until no objects are left.  For such a simple concept, this game has quite a fascinating theory.  In this talk, modular arithmetic and binary numbers are used to develop a winning strategy for this game and variations of the game.  The importance of Nim to the Sprague-Grundy Theory for impartial games will also be discussed.

 

Macroscopic ODE Models of Traffic Flow

 Zhengyi Zhou

Have you ever wondered how traffic lights are synchronized to minimize congestion? Macroscopic models of traffic flow using ordinary differential equations may help.  It is a relatively new and unexplored way of modeling effects of traffic lights on traffic flow.  In this study, a few models are constructed, numerically analyzed, and applied to a sequence of lights and a traffic junction in search for optimal traffic control strategies.  The main math tool used in this study is ordinary differential equations, but anyone with some calculus knowledge can understand the talk.