Colloquium
3:00 p.m., Friday (October 10, 2003)
Math Annex 1100
Yue-Xian Li
UBC
A Model of Calcium Waves and a Theory of Waves in Inhomogeneous Media
Many living creatures including human start their life when an egg cell is
penetrated by a sperm. One of the events immediately following sperm entry
is the occurrence of one or more waves of elevated Ca2+ concentration that
travel from the site of sperm entry to the opposite end of the cell. These
waves, called fertilization Ca2+ waves, are vital for the subsequent
development of the fertilized egg. In egg cells of some species, the first
few waves propagate further and further into the cellular space but fail
to reach the opposite end. These waves are called ``incomplete'' waves. In
this talk, I present a bidomain model of reaction-diffusion type that
explains how such incomplete waves can occur. The model reveals that
traveling fronts that propagate in an oscillatory manner, called tango
waves, can occur in an excitable medium in the presence of spatial
inhomogeneity. A preliminary theory is developed for studying stationary
and traveling fronts and pulses in a more general model for excitable
media. This study predicts a variety of experimental conditions under
which tango waves can occur. Other areas of biology in which this theory
may also apply will be discussed.
Refreshments will be served at 2:45 p.m. in the Faculty Lounge,
Math Annex (Room 1115).
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