BEGIN:VCALENDAR VERSION:2.0 PRODID:-// - ECPv6.16.5//NONSGML v1.0//EN CALSCALE:GREGORIAN METHOD:PUBLISH X-ORIGINAL-URL:https://aarms.math.ca X-WR-CALDESC:Events for REFRESH-INTERVAL;VALUE=DURATION:PT1H X-Robots-Tag:noindex X-PUBLISHED-TTL:PT1H BEGIN:VTIMEZONE TZID:America/Halifax BEGIN:DAYLIGHT TZOFFSETFROM:-0400 TZOFFSETTO:-0300 TZNAME:ADT DTSTART:20190310T060000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:-0300 TZOFFSETTO:-0400 TZNAME:AST DTSTART:20191103T050000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:-0400 TZOFFSETTO:-0300 TZNAME:ADT DTSTART:20200308T060000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:-0300 TZOFFSETTO:-0400 TZNAME:AST DTSTART:20201101T050000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:-0400 TZOFFSETTO:-0300 TZNAME:ADT DTSTART:20210314T060000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:-0300 TZOFFSETTO:-0400 TZNAME:AST DTSTART:20211107T050000 END:STANDARD BEGIN:DAYLIGHT TZOFFSETFROM:-0400 TZOFFSETTO:-0300 TZNAME:ADT DTSTART:20220313T060000 END:DAYLIGHT BEGIN:STANDARD TZOFFSETFROM:-0300 TZOFFSETTO:-0400 TZNAME:AST DTSTART:20221106T050000 END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTART;TZID=America/Halifax:20210305T160000 DTEND;TZID=America/Halifax:20210305T170000 DTSTAMP:20210113T130546Z CREATED:20200904T115630Z LAST-MODIFIED:20210113T130546Z UID:5709-1614960000-1614963600@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Steven Lester (King's College London) DESCRIPTION:The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-steven-lester-kings-college-london/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20210129T160000 DTEND;TZID=America/Halifax:20210129T170000 DTSTAMP:20201231T203710Z CREATED:20200904T115630Z LAST-MODIFIED:20201231T203710Z UID:5687-1611936000-1611939600@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Alan Lindsay (Notre Dame) DESCRIPTION:The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2021-01-29/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20210122T160000 DTEND;TZID=America/Halifax:20210122T170000 DTSTAMP:20201231T211013Z CREATED:20200904T115630Z LAST-MODIFIED:20201231T211013Z UID:5685-1611331200-1611334800@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Allan Greenleaf (Rochester) DESCRIPTION:The Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2021-01-22/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201204T160000 DTEND;TZID=America/Halifax:20201204T170000 DTSTAMP:20201231T203053Z CREATED:20200904T115630Z LAST-MODIFIED:20201231T203053Z UID:5475-1607097600-1607101200@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Peter Hintz (MIT) DESCRIPTION:Title: Linear stability of slowly rotating Kerr spacetimes\nAbstract: I will describe joint work with Dietrich Häfner and András Vasy in which we study the asymptotic behavior of linearized gravitational perturbations of Schwarzschild or slowly rotating Kerr black hole spacetimes. We show that solutions of the linearized Einstein equation decay at an inverse polynomial rate to a stationary solution (given by an infinitesimal variation of the mass and angular momentum of the black hole)\, plus a pure gauge term. The proof uses a detailed description of the resolvent of an associated wave equation on symmetric 2-tensors near zero energy. \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-16-2-2-2-3/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201127T160000 DTEND;TZID=America/Halifax:20201127T170000 DTSTAMP:20201123T152316Z CREATED:20200904T115630Z LAST-MODIFIED:20201123T152316Z UID:5472-1606492800-1606496400@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Graham Cox (Memorial University) DESCRIPTION:Title: Nodal deficiency via equipartition energy functionals and the Dirichlet-to-Neumann map\nAbstract: A classic result in differential equations is that the nth eigenfunction\nof a Sturm-Liouville boundary value problem has precisely n-1 zeros.\nCourant’s nodal domain theorem provides a natural generalization of this\nresult to higher dimensions\, but it is generally not sharp. The lack of\nsharpness is measured by the “nodal deficiency” of an eigenfunction.\nDespite over a century of intensive study\, this quantity is still not\nvery well understood. \nThe first explicit formula for the nodal deficiency was obtained in 2012\nby Berkolaiko\, Kuchment and Smilansky\, using an energy functional\ndefined on the space of equipartitions. More recently\, with Jones and\nMarzuola\, I obtained another formula for the nodal deficiency\, in terms\nof Dirichlet-to-Neumann operators defined on the eigenfunction’s nodal\ndomains. While originally derived using symplectic methods\, this result\ncan also be understood using the spectral flow generated by a family of\nboundary conditions imposed on the nodal set. In this talk I will\ndescribe this flow\, and explain how it provides a concrete mechanism by\nwhich low energy eigenfunctions do or do not contribute to the nodal\ndeficiency. I will also describe recent progress relating these two\nformulas for the nodal deficiency\, and hint at some applications to the\ntheory of spectral minimal partitions. \nThis talk represents joint work with Thomas Beck\, Gregory Berkolaiko\,\nIsabel Bors\, Yaiza Canzani\, Grace Conte\, Christopher Jones and Jeremy\nMarzuola. \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-16-2-2-2/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201106T160000 DTEND;TZID=America/Halifax:20201106T170000 DTSTAMP:20201108T225930Z CREATED:20200904T115630Z LAST-MODIFIED:20201108T225930Z UID:5470-1604678400-1604682000@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Reem Yassawi (Open University\, London) DESCRIPTION:Title: Some tame or wild Cantor dynamical systems\n Abstract: A topological dynamical system is a pair where is a compact metric spaces and is a group or semigroup acting continuously on . One algebraic invariant of a such a dynamical system is the Ellis semigroup.  The Ellis semigroup of a topological dynamical system is defined to be the compactification of the action in the topology of pointwise convergence on the space of all function .  Tameness is a concept whose roots date back to Rosenthal’s embedding theorem\, which says that if a sequence in does not have a weakly Cauchy subsequence\, then it must be a sequence on unit vectors in .  Köhler linked the concept of tameness to the Ellis semigroup.  A system is tame if its Ellis semigroup has size at most the continuum.  Non-tame systems are very far from tame\, as they must contain a copy of \, the Stone-Cech compactification of . \nIn this talk\, I will briefly survey the properties of the Ellis semigroup that make it an interesting object to study\, and discuss recent developments concerning tameness.  I will then discuss Toeplitz shifts\, which themselves have been studied extensively in this context and is the subject of some joint work with G. Fuhrmann and J. Kellendonk. \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-16-2-2-2-2/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201030T160000 DTEND;TZID=America/Halifax:20201030T170000 DTSTAMP:20201116T135614Z CREATED:20200904T115630Z LAST-MODIFIED:20201116T135614Z UID:5468-1604073600-1604077200@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Jean-Pierre Garbardo (McMaster University) DESCRIPTION:Title: Factorization of positive definite functions through convolution and the Turàn problem\n Abstract: If is a finite abelian group\, we call a subset symmetric if and whenever . We also let . We consider the problem of expressing an arbitrary positive definite function on as the convolution product of two positive definite functions\, one supported on and the other one supported on . We show that\, in the particular case where is the constant function \, this problem is related to the Tur\’an problem for positive definite functions. In the particular case of a finite abelian group\, this last problem asks the following question. Given a symmetric set \, find the maximum value of the sum if and is a positive definite function on supported on . We introduce the notion of  {\it dual Tur\’an problem for }\, which is essentially the Tur\’an problem for the set \, and show how the Tur\’an problem for and its dual are related\, and how the factorization mentioned above plays a role is solving both those problems. We will then give an overview of how these results can be extended to other abelian groups such as . \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-16-2-2/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201023T160000 DTEND;TZID=America/Halifax:20201023T170000 DTSTAMP:20201018T164418Z CREATED:20200904T115630Z LAST-MODIFIED:20201018T164418Z UID:5465-1603468800-1603472400@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Hari Kunduri (Memorial University) DESCRIPTION:Title: Geometric inequalities for axisymmetric black holes\nAbstract: In general relativity\, isolated\, dynamical black holes arise from asymptotically flat initial data for the Einstein equations. Such data are characterized by invariants such as the ADM mass and angular momentum. When angular momentum is conserved in the evolution\, the\nstandard picture of gravitational collapse suggests an inequality relating the ADM mass and angular momentum. Such geometric inequalities have been rigorously proved for axisymmetric\, asymptotically flat maximal initial data for the vacuum Einstein equations. I will discuss recent work on extending this class of inequalities to higher dimensions\, where a number of qualitative differences arise (e.g. black holes can have non-spherical horizon topology). In particular\, I will discuss how a lower bound for the mass\, in terms of a (regularized) harmonic energy functional is obtained. \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-16-2/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201016T160000 DTEND;TZID=America/Halifax:20201016T170000 DTSTAMP:20200923T163932Z CREATED:20200904T115630Z LAST-MODIFIED:20200923T163932Z UID:5459-1602864000-1602867600@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Julie Rowlett (Chalmers\, Sweden) DESCRIPTION:Decisions and Disease\nDo you usually get a flu shot every year? Do you usually take preventive measures to avoid contracting sexually transmitted infections? It is reasonable to expect that while many people may answer `no‘ to the first question\, they may answer `yes‘ to the second question. In recent joint work with my PhD student\, Carl-Joar Karlsson\, we have discovered a mathematical explanation for these different choices. Here I will explain mathematical models we have developed that combine the spread of different types of diseases together with the evolution of human behavioral choices. These models create dynamical systems\, and the stable equilibrium points provide insights into both the spread of disease as well as the evolution of human behaviors. These insights may be relevant for both the current pandemic as well as any new diseases we may encounter in the future. \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-16/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20201002T160000 DTEND;TZID=America/Halifax:20201002T170000 DTSTAMP:20200927T175953Z CREATED:20200904T115630Z LAST-MODIFIED:20200927T175953Z UID:5461-1601654400-1601658000@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: John Toth (McGill University) DESCRIPTION:Title: Pointwise bounds for joint eigenfunctions of quantum completely integrable (QCI) systems \nAbstract: I will discuss some recent results on improvements in supremum bounds for joint eigenfunctions of QCI systems together with sharp exponential decay estimates away from the projections of invariant Lagrangian tori (ie. in the microlocally forbidden region). This is joint work with Jeff Galkowski. \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-10-02/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT BEGIN:VEVENT DTSTART;TZID=America/Halifax:20200925T160000 DTEND;TZID=America/Halifax:20200925T170000 DTSTAMP:20200916T212745Z CREATED:20200904T115630Z LAST-MODIFIED:20200916T212745Z UID:5427-1601049600-1601053200@aarms.math.ca SUMMARY:Dalhousie-AARMS AAMP Seminar: Michael Ward (UBC) DESCRIPTION:Synchrony and Oscillatory Dynamics for a 2-D PDE-ODE Model of Diffusion-Sensing with Small Signaling Compartments\nWe analyze a class of cell-bulk coupled PDE-ODE models\, motivated by quorum and diffusion sensing phenomena in microbial systems\, that characterize communication between localized spatially segregated dynamically active signaling compartments or “cells” that have a permeable boundary. In this model\, the cells are disks of a common radius and they are spatially coupled through a passive extracellular bulk diffusion field with diffusivity in a bounded 2-D domain. Each cell secretes a signaling chemical into the bulk region at a constant rate and receives a feedback of the bulk chemical from the entire collection of cells. This global feedback\, which activates signaling pathways within the cells\, modifies the intracellular dynamics according to the external environment. The cell secretion and global feedback are regulated by permeability parameters across the cell membrane. For arbitrary reaction-kinetics within each cell\, the method of matched asymptotic expansions is used in the limit of small cell radius to construct steady-state solutions of the PDE-ODE model\, and to derive a globally coupled nonlinear matrix eigenvalue problem (GCEP) that characterizes the linear stability properties of the steady-states. The analysis and computation of the nullspace of the GCEP as parameters are varied is central to the linear stability analysis. In the limit of large bulk diffusivity\, an asymptotic analysis of the PDE-ODE model leads to a limiting ODE system for the spatial average of the concentration in the bulk region that is coupled to the intracellular dynamics within the cells. Results from the linear stability theory and ODE dynamics are llustrated for Sel’kov reaction-kinetics\, where the kinetic parameters are chosen so that each cell is quiescent when uncoupled from the bulk medium. For various specific spatial configurations of cells\, the linear stability theory is used to construct phase diagrams in parameter space characterizing where a switch-like emergence of intracellular oscillations can occur through a Hopf bifurcation. The effect of the membrane permeability parameters\, the reaction-kinetic parameters\, the bulk diffusivity\, and the spatial configuration of cells on both the emergence and synchronization of the oscillatory intracellular dynamics\, as mediated by the bulk diffusion field\, is analyzed in detail. The linear stability theory is validated from full numerical simulations of the PDE-ODE system\, and from the reduced ODE model when is large. \nJoint work with Sarafa Iyaniwura (UBC) and Jia Gou (UC Riverside). \nThe Dalhousie-AARMS Analysis-Applied Math-Physics Seminar takes place on Fridays from 4 – 5 pm Atlantic Time over Zoom.  If you would like to attend\, please email the organizers for connection details. URL:https://aarms.math.ca/event/dalhousie-aarms-aamp-seminar-2020-09-25/ LOCATION:Zoom seminar CATEGORIES:AAMP Seminar ORGANIZER;CN="Suresh Eswarathasan":MAILTO:sr766936@dal.ca END:VEVENT END:VCALENDAR