Seminars and Colloquiums
for week of September 5, 2011
Speaker:
Professor Rafael del Rio, IIMAS – UNAM, Mexico City, Tuesday
Dr. William R. Holmes of the University of British Columbia, Tuesday
Professor Stefan Richter, Wednesday
Mr. Zhen Guan, Wednesday
Dr. Juanjuan Chai, NIMBioS postdoc, Thursday
Dr. Bill Holmes, University of British Columbia, Thursday
If you are interested in giving or arranging a talk for one of our seminars or colloquiums,
please review our calendar.
If you have questions, or a date you would like to confirm, please contact Dr. Judy Day.
Tuesday, September 6
DE/COMPUTATIONAL MATH SEMINAR
TIME: 11:30 – 12:30
ROOM: Ayres 121
SPEAKER: Professor Rafael del Rio, IIMAS – UNAM, Mexico City
TITLE: "Inverse problems for Jacobi operators : Interior mass-spring perturbations in finite systems"
ABSTRACT: This talk will be about joint work with Mikhail Kuryavtsev. We consider
a linear finite spring mass system which is perturbed by modifying one mass and adding one spring. From knowledge of the natural frequencies of the original and the perturbed systems we study when masses and springs can be reconstructed. This is a problem about rank two or rank three type perturbations of finite Jacobi matrices where we are able to describe quite explicitly the associated Green's functions. We give necessary and sufficient conditions for two given sets of points to be eigenvalues of the original and modified system respectively.
Joint NIMBioS and Mathematics Department Colloquium
TIME: 3:30 pm
ROOM: NIMBioS Lecture Hall (4th floor Blount Hall)
SPEAKER: Dr. William R. Holmes of the University of British Columbia
TITLE: "A local analysis of symmetry breaking with applications to HeLa
cell polarization: Theory and experiment"
ABSTRACT: Polarization, symmetry breaking, and more generally patterning play a vital role in many cellular functions including chemotaxis, the topic of this work. During chemotaxis, mammalian
cells sense an external gradient of attractant (or repellant). This leads to re-organization of regulatory molecules (Rho-GTPases and Phosphoinositides (PIs)) that control the highly choreographed growth,
contraction, and destruction of the cytoskeleton, which is necessary for motion. I will discuss recent collaborative work (with the experimental group of Andre Levchenko - JHU) that explores the
biomolecular interactions that lead to polarization in a specific cell type (HeLa). A `wave pinning' based model incorporating Rho-GTPases and PIs with feedback between them will be presented. A brief
overview of the relevant biochemical / biomechanical machinery responsible for motility will be given to present a complete picture. An overview of modelling techniques used in this field will be given with an emphasis on the mathematical basis of a new class of pattern forming models, referred to as `wave pinning' (Mori et al., Biophys J. 2008). New pseudo-analytic methods, involving only ODE techniques and the use of packaged numerical continuation software (eg. Auto or MatCont), for simultaneously performing linear stability analysis, Turing stability analysis, and detecting threshold based patterning (eg. Wave pinning) will be presented. This will be used to analyze the discussed model and connect it to experiments, providing hypotheses about the underlying biochemical interactions responsible for polarization.
Wednesday, September 7
ANALYSIS SEMINAR
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 113
SPEAKER: Professor Stefan Richter
TITLE: "Cyclic functions in spaces of analytic functions of several complex variables II"
ABSTRACT: A function f is called cyclic in a space H, if the polynomial multiples of f are dense in H. For analytic functions of a single variable investigations about cyclic vectors are a classical topic: Many nontrivial results are known and challenging open problems remain. I will discuss some results and open questions about functions of several variables.
ORAL SPECIALTY EXAM
TIME: 3:30 p.m.
ROOM: Ayres 110
SPEAKER: Mr. Zhen Guan
His committee consist of Professors: Wise (chair), Alexiades, and Todorova.
Thursday, September 8
MATH BIOLOGY SEMINAR
TIME: 12:45 – 1:35 p.m.
ROOM: NIMBioS classroom
SPEAKER: Dr. Juanjuan Chai, NIMBioS postdoc
TITLE: Passive Diffusion in Ecosystems, part 2
JUNIOR COLLOQUIUM
TIME: 3:35 – 4:25 p.m.
ROOM: Ayres 401
SPEAKER: Dr. Bill Holmes, University of British Columbia, Alumnus of UTK
TITLE: "Foundations of wave propagation in biology and ecology"
ABSTRACT: What controls the speed of disease spread? How does the heart beat?
How do white blood cells track down and eat a pathogen? While these biological phenomena range from large to very small in scale and seemingly have very little in common, each can be thought of as a
problem in wave propagation. In this talk I will discuss the mathematics used to explores these types of questions. We'll look at systems of both historic and current interest and use techniques from
ordinary differential equations (ODE's) to explore the formation and propagation of waves in reaction diffusion systems. A premium will be placed on providing an intuitive understanding of the mechanisms
at work and using that understanding to motivate the mathematical structure used to describe them. Familiarity with ODE's and a basic understanding of the concept of diffusion will be helpful.
Please join us for pizza at 3:15 p.m.
Past notices:
Seminars from 2010-2011 academic year
Seminars from 2009-2010 academic year
Seminars from 2008-2009 academic year
Seminars from 2007-2008 academic year
Seminars from 2006-2007 academic year