**Junior Colloquium - 2017-2018**

**Thursday, April 12**

Title: FSNSYWTIZHYNTSYTHWDUYTLWFUMD

**Speaker: Anne Ho, University of Tennessee **

Time: 3:40 PM-4:35 PM

Room: Ayres 405

This talk is about secret messages, hackers, Julius Caesar, the FBI, data breaches, number theory, and puzzles. Your first puzzle is the title of this talk. During the presentation, we will discuss more puzzles, historical ciphers, and relevant current events.

Pizza in A 401 at 3:15, bring your drink.

**Thursday, March 28**

Title: Adding and counting: as easy as 1, 2, 3…

**Speaker: Marie Jameson, University of Tennessee **

Time: 3:40 PM-4:35 PM

Room: Ayres 405

In this talk, we’ll dive into the theory of “integer partitions,” which are combinatorial objects that are very easy to define: a partition of a positive integer n is just a way of writing n as a sum of positive integers. Although partitions are simple to define, it turns out that they have very surprising properties and far-reaching connections to other areas of study.

Pizza in A 408 at 3:15, please bring your own drink.

**Thursday, March 22**

Title: Math and Materials Science and Engineering

*Speaker: Claudia Rawn, University of Tennessee *

Time: 3:40 PM-4:35 PM

Room: Ayres 405

Materials Science and Engineering (MSE) is meeting ground for Biology (biomaterials), Chemistry, Mathematics, and Physics. MSE students at the University of Tennessee, Knoxville take Calculus I, II, III, Matrix Computations, and Differential Equations I. The foundation of MSE is structure-processing-properties where structure can be on various scales including the atomic scale or on the order of 10-10 m or an Å. X-ray diffraction is a tool used for probing the atomic structure. Like each person has a unique fingerprint each compound with its unique atomic arrangement and chemistry has a unique diffraction pattern. We can calculate the position of the diffraction peaks by knowing the dimensions of the smallest repeating building block and the intensity of the peaks by the atom species and locations. Which peaks are absent depend on the symmetry of the atomic arrangement. In this seminar we will talk about the history of X-ray and neutron diffraction and go over some of the equations we use for the calculations above.

Pizza will be served in A 401 at 3:20, bring your drink.

**Thursday, March 8**

Title: Asymptotic error analysis

** Speaker: Brian Wetton, University of British Columbia **Time: 3:40 PM-4:35 PM

Room: Ayres 405

When computing numerical approximations to problems with smooth solutions using regular grids, the error can have additional structure. The historical example of the Euler-McLaurin formula for the approximation of integrals with the trapezoidal rule is shown. This expansion can be used to justify Richardson extrapolation of the approximations leading to the Romberg integration formula. For approximation of differential equations, similar error expansions can be derived. For standard methods on uniform grids, an expansion for the error can be constructed that is regular in the grid spacing. For some other methods, numerical artifacts (boundary layers and errors that alternate in sign between adjacent grid points) can also be present. Identifying the types of errors that are generated by a given scheme and the order at which they occur is called Asymptotic Error Analysis. Several examples are shown, including the error analysis of cubic spline interpolation which is shown to have numerical boundary layers. A numerical artifact from an idealized adaptive grid with hanging nodes used to approximate a simple elliptic problem is presented.

Join us for Pizza in A 408 at 3:15, but bring your drink.

**Thursday, February 8**

Title: How to teleport a goat in five easy steps

**Speaker: Remus Nicoara, University of Tennessee **

Time: 3:40 PM-4:30 PM (Arrive at 3:20 for pizza in Ayres 408)

Room: Ayres 405

We will discuss the mathematics behind the (theoretical) quantum teleportation of a goat. An important role in this process is played by Hadamard matrices, which are chessboard-like patterns of colors satisfying certain rules. Other applications of Hadamard matrices will also be presented.

**Thursday, November 2**

Title: Zombie Attack! Modeling the Dynamics of a Zombie Apocalypse

**Speaker: Dr. Christopher Strickland, UTK **

Time: 3:40-4:35pm

Room: Ayres 405

Abstract: In this talk, I present several differential equation models for zombie invasion and analyze them to determine the fate of mankind. Largely based off the 2009 paper "When Zombies Attack!: Mathematical Modelling of an Outbreak of Zombie Infection" by Munz et al., this talk will serve as an introduction to epidemiological modeling and present basic dynamical systems analysis for nonlinear systems. It will be of particular interest to any students currently taking MATH 231 or especially MATH 431, since the simplest zombie model is easily analyzed by hand and can serve as an example of Jacobian eigenvalue/eigenvector methods. There will also be plenty of zombie pictures.

Pizza will be served in A 408 @ 3:15, bring your drink.

**Thursday, October 12**

Title: Transionospheric Synthetic Aperture Imaging

**Speaker: Dr. Erick Smith, US Naval Research Laboratory**

Time: 3:40-4:35pm

Room: Ayres 405

* Note: Math majors who would like to join the speaker for a lunch or dinner (to be scheduled) should get in touch with Ken Stephenson, kstephe2@utk.edu.

Synthetic Aperture Radars (SAR) use microwaves to image the surface of the Earth (or other planets) from above, usually by airplanes or satellites. From the standpoint of mathematics, SAR imaging is an inverse problem of reconstructing certain characteristics of the target from the information contained in the radio waves reflected off this target. It can be done at nighttime and even through cloud cover. Radars that operate in the UHF and VHF bands, with frequencies of hundreds of MHz, also can penetrate foliage and the ground to see more, but if the radar is located on a satellite, images in these frequencies are also susceptible to distortions caused by the ionosphere, a dynamic region of the atmosphere containing a high concentration of ions and free electrons.

In this talk, we will look at problems associated with spaceborne synthetic aperture imaging in these frequencies and the mathematical ways to correct for the distortions, with the primary methodology stemming from asymptotic analysis and perturbation theory. This is done without prior knowledge of the current state of the ionosphere, which is both inhomogeneous and anisotropic as well as constantly changing in time and having both deterministic and stochastic components. We also look at anisotropy in the target and how certain material parameters can be determined from the phenomenologically constructed scattering matrix. Besides mathematicians, the presentation should also be of interest to those with physics and electrical engineering backgrounds.

Published earlier this year and the basis for this talk, Transionospheric Synthetic Aperture Imaging is a follow-up to the speaker’s 2013 dissertation, SAR Imaging Through the Earth’s Ionosphere, incorporating the contents of the dissertation as well as work that came before it and afterwards.

**Thursday, September 21**

Title: Generatingfunctionology

**Speaker: Carl Wagner, UTK**

Time: 3:40 pm – 4:35

Room: Ayres 405

Abstract: We'll see how multiplying various power series leads to the solution of many interesting problems in enumerative combinatorics.

Pizza will be served at 3:20 in A 408. Please bring your own drink.

**Thursday, September 7**

Title: TBA

**Speaker: Sergey Gavrilets, Distinguished Professor, EEB/Math**

Time: 3:40 pm – 4:35, Arrive at 3:15 for pizza

Room: Ayres 405

Pizza will be served at 3:15 in A 401. Please bring your own drink.

Previous Junior Colloquiums: