## Colloquium and Seminar Schedule

Fall 2011This is the schedule of colloquia and seminars inthe Department of Mathematics and Computer Science for this semester.

Click here for information about the next scheduled talk. Check this page regularly for the latest schedule as more talks are added.

## September 2011

Two-faced: The Cantor set and notions of size

Speaker: Dr. Emilie Wiesner, Ithaca College

Date: Thursday, September 29th

Time: 4:45pm

Location: Napier 201

(Refreshments will be served beforehand.)

Abstract:

The Cantor set is a specially constructed infinite set; it has earned its name from an appearance in an 1883 paper of the mathematician Georg Cantor. The Cantor set has many remarkable properties, and I will be talking about a few of them. In particular, I'll discuss how two ways of defining size ("measure" and "cardinality") lead to two very different ideas of how big this set really is!

## October 2011

Mathematical Models of Bone Biochemistry with Applications to the Treatment of Osteoporosis

Speaker: David Ross, Rochester Institute of Technology

Date: Wednesday, October 26th

Time: 4:30pm

Location: Napier 201

(Refreshments will be served beforehand.)

Abstract:

In humans and other mammals the skeleton is continuously remodeled, that is, dissolved and rebuilt; human bone has an annual turnover rate of about 10 percent. Understanding the biochemical processes of bone remodeling is important to the development of treatments for the disease osteoporosis, which is characterized by low bone mass, and which puts those who have it at risk of bone fractures. Osteoporosis results from an imbalance in the biochemical remodeling process, when resorption-the chemical breakdown of old bone-outstrips the formation of new bone. The most common cause of osteoporosis is age-related hormone change, the reduction of estrogen in women after menopause, and the reduction of testosterone in older men. Roughly 20 percent of women over the age of 50 have osteoporosis.In this talk Professor Ross will discuss dynamical system models of bone remodeling that are used to simulate bone remodeling and to study the effects of various treatments for the condition. He will focus on the ways in which the dynamical systems capture the important biochemical features of the remodeling process, and he will discuss modeling methodology and the ways in which models are used.

## November 2011

A Mathematical Model of T Cell Exhaustion Caused by HBV/HDV

Speaker: Yaoxin Liu '12

Date: Tuesday, November 9th

Time: 4:30 pm

Location: Napier 201

(Refreshments will be served beforehand.)

Abstract:

Abstract: In patients with chronic hepatitis B infection, the immune system becomes exhausted, losing its effectiveness over time. Co-infection with another virus, Hepatitis Delta, reduces the amount of HBV in the blood, and so may relieve the exhaustion. During the Summer Research Program last summer, Yixiao Sha, Yaoxin Liu and Prof. Jonathan Forde developed an ordinary differential equation model of the interactions of these two viruses and the immune system to study the effect of a second infection on immune exhaustion. Sha, Liu and Forde started by studying the four dimensional model with only HBV infection, and then added the second virus, HDV. They also analyzed various steady states and their stability for both systems. All the stability conditions are found for the four dimensional system with only HBV infection. For the five dimensional system with HDV, numerical simulations show the existence of positive steady states representing chronic coinfection. The model suggests that co-infection does not reduce the exhaustion level, but increases damage due to general inflammation.

If Copernicus and Kepler Had Computers:

An Introduction to Model- Building and Computational Science

Speaker: Charles Van Loan, Cornell University

Date: Thursday, November 17th

Time: 5:00pm

Location: Napier 201

(Refreshments will be served beforehand.)

Abstract:

If you watch Mars against the backdrop of the fixed stars, then night after night you'll see rather steady progress across the zodiac. But every so often, the planet appears to "back-up" before continuing on its forward trek. This periodic, retrograde motion wreaks havoc with a model of the solar system that places each planet on a steadily rotating circle with Earth at the center. Ptolemy did a pretty good job patching up the model by placing each planet on a small rotating circle whose center is on the rim of a larger rotating circle. The path traced out is called an epicycle and it offers some explanation for Mars' orbital wanderings. The epicycle model lasted for centuries until Copernicus set the record straight by suggesting that the Earth revolved around the sun along with the other planets. But would he have been so bold a scientist if he had access to 2011 computers? Or would he have just mouse-clicked his way into fame, developing a simulation package that supported further tinkering with the Ptolemaic model?

Movie:The Proof

Date: Thursday, December 1st

Time: 7:30pm

Location: Albright Auditorium

(Refreshments will be served!!!)

Abstract:

For over 350 years, some of the greatest minds of science struggled to prove what was known as Fermat's Last Theorem -- the idea that a certain simple equation had no solutions. Now hear from the man who spent seven years of his life cracking the problem, read the intriguing story of an 18th century woman mathematician who hid her identity in order to work on Fermat's Last Theorem, and demonstrate that a related equation, the Pythagorean Theorem, is true. Andrew Wiles devoted much of his career to proving Fermat's Last Theorem, a challenge that perplexed the best minds in mathematics for 300 years. In 1993, he made front-page headlines when he announced a proof of the problem, but this was not the end of the story; an error in his calculation jeopardized his life's work. In this interview, Wiles recounts how he came to terms with the mistake, and eventually went on to achieve his life's ambition.

## Past Colloquia Series

Spring 2011 Fall 2010 Spring 2010 Fall 2009 Spring 2008 Fall 2008

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

please contact Erika King at eking@hws.edu or at (315) 781-3355