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<str<strong>on</strong>g>European</str<strong>on</strong>g> <str<strong>on</strong>g>C<strong>on</strong>ference</str<strong>on</strong>g> <strong>on</strong> Ma<str<strong>on</strong>g>th</str<strong>on</strong>g>ematical and Theoretical Biology 2011<br />
Modelling bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilms: from gene regulati<strong>on</strong> to large-scale structure and<br />
functi<strong>on</strong>; Wednesday, June 29, 17:00<br />
Hermann Eberl<br />
University <str<strong>on</strong>g>of</str<strong>on</strong>g> Guelph<br />
e-mail: heberl@uoguelph.ca<br />
A numerical me<str<strong>on</strong>g>th</str<strong>on</strong>g>od for a doubly degenrate<br />
diffusi<strong>on</strong>-reacti<strong>on</strong> model describing bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilm processes<br />
Some bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilm systems and processes can be described by quasilinear parabolic equati<strong>on</strong>s<br />
for vanishing biomass density, and (ii) a super-diffusi<strong>on</strong> singularity when <str<strong>on</strong>g>th</str<strong>on</strong>g>e<br />
maximum biomass density is reached. Phenomen<strong>on</strong> (i) guarantees a well defined<br />
interface between <str<strong>on</strong>g>th</str<strong>on</strong>g>e bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilm and <str<strong>on</strong>g>th</str<strong>on</strong>g>e surrounding aqueous phase <str<strong>on</strong>g>th</str<strong>on</strong>g>at moves at<br />
finite speed, phenomen<strong>on</strong> (ii) ensures <str<strong>on</strong>g>th</str<strong>on</strong>g>at <str<strong>on</strong>g>th</str<strong>on</strong>g>e maximum biomass density is not exceeded.<br />
In numerical simulati<strong>on</strong>s bo<str<strong>on</strong>g>th</str<strong>on</strong>g> <str<strong>on</strong>g>th</str<strong>on</strong>g>ese aspects are not easy to deal wi<str<strong>on</strong>g>th</str<strong>on</strong>g>. We<br />
discuss a simple, yet relatively robust numerical me<str<strong>on</strong>g>th</str<strong>on</strong>g>od. We show <str<strong>on</strong>g>th</str<strong>on</strong>g>at under <str<strong>on</strong>g>th</str<strong>on</strong>g>is<br />
numerical realisati<strong>on</strong> <str<strong>on</strong>g>th</str<strong>on</strong>g>e effects <str<strong>on</strong>g>of</str<strong>on</strong>g> (i) and (ii) are maintained, we give a stability<br />
result, show c<strong>on</strong>vergence numerically by grid refinement, and discuss <str<strong>on</strong>g>th</str<strong>on</strong>g>e parallel<br />
<str<strong>on</strong>g>European</str<strong>on</strong>g> <str<strong>on</strong>g>C<strong>on</strong>ference</str<strong>on</strong>g> <strong>on</strong> Ma<str<strong>on</strong>g>th</str<strong>on</strong>g>ematical and Theoretical Biology 2011 Modelling bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilms: from gene regulati<strong>on</strong> to large-scale structure and functi<strong>on</strong>; Wednesday, June 29, 17:00 Hermann Eberl University <str<strong>on</strong>g>of</str<strong>on</strong>g> Guelph e-mail: heberl@uoguelph.ca A numerical me<str<strong>on</strong>g>th</str<strong>on</strong>g>od for a doubly degenrate diffusi<strong>on</strong>-reacti<strong>on</strong> model describing bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilm processes Some bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilm systems and processes can be described by quasilinear parabolic equati<strong>on</strong>s wi<str<strong>on</strong>g>th</str<strong>on</strong>g> two n<strong>on</strong>-Fickian diffusi<strong>on</strong> effects: (i) degeneracy <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>th</str<strong>on</strong>g>e diffusi<strong>on</strong> coefficients for vanishing biomass density, and (ii) a super-diffusi<strong>on</strong> singularity when <str<strong>on</strong>g>th</str<strong>on</strong>g>e maximum biomass density is reached. Phenomen<strong>on</strong> (i) guarantees a well defined interface between <str<strong>on</strong>g>th</str<strong>on</strong>g>e bi<str<strong>on</strong>g>of</str<strong>on</strong>g>ilm and <str<strong>on</strong>g>th</str<strong>on</strong>g>e surrounding aqueous phase <str<strong>on</strong>g>th</str<strong>on</strong>g>at moves at finite speed, phenomen<strong>on</strong> (ii) ensures <str<strong>on</strong>g>th</str<strong>on</strong>g>at <str<strong>on</strong>g>th</str<strong>on</strong>g>e maximum biomass density is not exceeded. In numerical simulati<strong>on</strong>s bo<str<strong>on</strong>g>th</str<strong>on</strong>g> <str<strong>on</strong>g>th</str<strong>on</strong>g>ese aspects are not easy to deal wi<str<strong>on</strong>g>th</str<strong>on</strong>g>. We discuss a simple, yet relatively robust numerical me<str<strong>on</strong>g>th</str<strong>on</strong>g>od. We show <str<strong>on</strong>g>th</str<strong>on</strong>g>at under <str<strong>on</strong>g>th</str<strong>on</strong>g>is numerical realisati<strong>on</strong> <str<strong>on</strong>g>th</str<strong>on</strong>g>e effects <str<strong>on</strong>g>of</str<strong>on</strong>g> (i) and (ii) are maintained, we give a stability result, show c<strong>on</strong>vergence numerically by grid refinement, and discuss <str<strong>on</strong>g>th</str<strong>on</strong>g>e parallel speed-up gained <strong>on</strong> OpenMP platforms. 262
<str<strong>on</strong>g>European</str<strong>on</strong>g> <str<strong>on</strong>g>C<strong>on</strong>ference</str<strong>on</strong>g> <strong>on</strong> Ma<str<strong>on</strong>g>th</str<strong>on</strong>g>ematical and Theoretical Biology 2011 Recent advances in infectious disease modelling II; Saturday, July 2, 14:30 Raluca Eftimie McMaster University e-mail: reftimie@ma<str<strong>on</strong>g>th</str<strong>on</strong>g>.mcmaster.ca Using viruses to eliminate tumours: <str<strong>on</strong>g>th</str<strong>on</strong>g>e role <str<strong>on</strong>g>of</str<strong>on</strong>g> multi-stability and multi-instability phenomena Recent advances in virology, gene <str<strong>on</strong>g>th</str<strong>on</strong>g>erapy and molecular and cell biology have provided insight into <str<strong>on</strong>g>th</str<strong>on</strong>g>e mechanisms <str<strong>on</strong>g>th</str<strong>on</strong>g>rough which viruses can boost <str<strong>on</strong>g>th</str<strong>on</strong>g>e antitumour immune resp<strong>on</strong>se, or can infect and kill directly tumour cells. Here, we derive a ma<str<strong>on</strong>g>th</str<strong>on</strong>g>ematical model to investigate <str<strong>on</strong>g>th</str<strong>on</strong>g>e anti-tumour effect <str<strong>on</strong>g>of</str<strong>on</strong>g> two viruses and <str<strong>on</strong>g>th</str<strong>on</strong>g>eir interacti<strong>on</strong>s wi<str<strong>on</strong>g>th</str<strong>on</strong>g> <str<strong>on</strong>g>th</str<strong>on</strong>g>e immune cells. We <str<strong>on</strong>g>th</str<strong>on</strong>g>en discuss <str<strong>on</strong>g>th</str<strong>on</strong>g>e role <str<strong>on</strong>g>of</str<strong>on</strong>g> virus persistence <strong>on</strong> <str<strong>on</strong>g>th</str<strong>on</strong>g>e eliminati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> tumour cells. To <str<strong>on</strong>g>th</str<strong>on</strong>g>is end, we focus <strong>on</strong> multi-stability and multi-instability, two complex phenomena <str<strong>on</strong>g>th</str<strong>on</strong>g>at can cause abrupt transiti<strong>on</strong>s between different states in biological and physical systems. In <str<strong>on</strong>g>th</str<strong>on</strong>g>e c<strong>on</strong>text <str<strong>on</strong>g>of</str<strong>on</strong>g> cancer immuno<str<strong>on</strong>g>th</str<strong>on</strong>g>erapies, <str<strong>on</strong>g>th</str<strong>on</strong>g>e transiti<strong>on</strong>s between a tumour-free and a tumour-present state were so far associated wi<str<strong>on</strong>g>th</str<strong>on</strong>g> <str<strong>on</strong>g>th</str<strong>on</strong>g>e multi-stability phenomen<strong>on</strong>. Here, we show <str<strong>on</strong>g>th</str<strong>on</strong>g>at <str<strong>on</strong>g>th</str<strong>on</strong>g>e multi-instability phenomen<strong>on</strong> can lead to <str<strong>on</strong>g>th</str<strong>on</strong>g>e formati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> a homoclinic bifurcati<strong>on</strong>, which causes <str<strong>on</strong>g>th</str<strong>on</strong>g>e system to switch from a tumour-present to a tumourfree state. This multi-instability phenomen<strong>on</strong> is driven by <str<strong>on</strong>g>th</str<strong>on</strong>g>e persistence <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>th</str<strong>on</strong>g>e virus, while <str<strong>on</strong>g>th</str<strong>on</strong>g>e multi-stability phenomen<strong>on</strong> is driven by <str<strong>on</strong>g>th</str<strong>on</strong>g>e immune resp<strong>on</strong>se. 263