Atlantic Graph Theory Seminar: Dr Jared Howell (Memorial University of Newfoundland, Grenfell Campus)
2020-11-25 15:30 - 16:30 UTC | Zoom seminar
Gracefully labelling windmills using Skolem-like sequences
To gracefully label a graph G, assign each vertex v ∊ V(G) a distinct label l(v) from {0,1,2,…,|E(G)|}, such that {|l(u)-l(v)| : uv ∊ E(G)}={1,2,3,…,|E(G)|}. In this talk we will examine constructive techniques using Skolem-like sequences to gracefully label windmills of cycles. This includes new constructive techniques for known results as well as new results on windmills with vanes of mixed cycle length.
The Atlantic Graph Theory Seminar series will take place every Wednesday from 3:30-4:30 ADT online via zoom. The talks, provided by researchers, postdocs and graduate students, will be on a variety of current topics in graph theory. If you would like to give a talk or attend, please email one of the organizers (Jason Brown and Danielle Cox).

Atlantic GR Seminar: Jinzhao Wang (ETH Zurich) and Saikat Mondal (MUN)
2020-11-25 13:00 - 14:00 (America/Halifax) | Zoom seminar
Outer entropy equals Bartnik-Bray inner mass, and the gravitational ant conjecture
Jinzhao Wang (ETH Zurich)
Entropy and energy are found to be closely tied on our quest for quantum gravity. We point out an interesting connection between the recently proposed outer entropy, a coarse-grained entropy defined for a compact spacetime domain motivated by the holographic duality, and the Bartnik-Bray quasilocal mass long known in the mathematics community. In both scenarios, one seeks an optimal spacetime fill-in of a given closed, connected, spacelike, codimension-two boundary. We show that for an outer-minimizing mean-convex surface, the Bartnik-Bray inner mass matches exactly with the irreducible mass corresponding to the outer entropy. The equivalence implies that the area laws derived from the outer entropy are mathematically equivalent as the monotonicity property of the quasilocal mass. It also gives rise to new bounds between entropy and the gravitational energy, which naturally gives the gravitational counterpart to Wall’s ant conjecture. We also observe that the equality can be achieved in a conformal flow of metrics, which is structurally similar to the Ceyhan-Faulkner proof of the ant conjecture. We compute the small sphere limit of the outer entropy and it is proportional to the bulk stress tensor as one would expect for a quasilocal mass.
Marginally outer trapped (open) surfaces in Schwarzschild geometry and extreme mass ratio merger
Saikat Mondal (MUN)
Black holes are one of the common objects in astrophysics. Some are formed from a dying star, called a stellar black hole. There are also supermassive black holes consisting of mass millions or even billions times that of the sun. Such black holes are thought to lie at the center of almost every galaxy. In this talk we will explore the evolution of horizons of black hole mergers in a special limit called the ” extreme mass ratio” limit. For example, a supermassive black hole merges with a stellar black hole to become a single black hole. In this limit, the merging horizons can be studied with the help of simple numerics. We will discuss mainly about marginally outer trapped surfaces (MOTS). Interestingly, the MOTSs we find in our numerical analysis have an arbitrary number of self-intersections.
The Atlantic General Relativity 2020 online postdoc/student seminar series is in the tradition of the annual AGR meetings, providing a forum not only for students and postdocs to present their research and make professional contacts but also to facilitate connections and collaborations between all Atlantic Canadian relativists. The series is student-organized and includes all areas of classical and quantum gravity. Talks will occur on the last Wednesday of every month, with each session consisting of two 30 minute talks. If you would like to attend, please email the organizers for connection details.

Atlantic Graph Theory Seminar: Kyle MacKeigan (PhD Candidate, Dalhousie University)
2020-11-18 15:30 - 16:30 UTC | Zoom seminar
Orthogonal Colourings of Graphs
Two colourings of a graph are orthogonal if they have the property that when two vertices receive the same colour in one colouring, then those vertices receive distinct colours in the other colouring. In this talk, the importance of perfect orthogonal colourings is demonstrated. Then, perfect orthogonal colourings of Cayley graphs and tree graphs are constructed. To conclude, it is shown how the Cartesian, tensor, and strong graph product can be used to generate perfect orthogonal colourings.
The Atlantic Graph Theory Seminar series will take place every Wednesday from 3:30-4:30 ADT online via zoom. The talks, provided by researchers, postdocs and graduate students, will be on a variety of current topics in graph theory. If you would like to give a talk or attend, please email one of the organizers (Jason Brown and Danielle Cox).

AARMS COVID-19 Seminar: Shannon LeBlanc (Dept of Health NB)
2020-11-18 15:00 - 16:30 (America/Halifax) | Zoom seminar
Importation Risk under the Northern Lights
To understand the risk that an infectious traveler from other Canadian provinces and territories will enter the Northwest Territories the Government of the Northwest Territories has fitted jurisdictional reported COVID-19 transmission data to a simple SEIR model. Using the most recent epidemiological parameters for transmission we estimate the likelihood that a pre-symptomatic or asymptomatic/unreported COVID-19 case will travel to the NWT at time t. We have mapped territorial travel data collected since May 2020 to identify the points in time that our importation risk was highest. Using the output of the importation risk model we have developed a Markov tree to assist public health decision makers in understanding the risk that these travelers pose to the public based on the testing and quarantine strategies that they choose to apply.
Shannon LeBlanc is currently an Epidemiologist at the New Brunswick Department of Health who has recently worked with the government of the Northwest Territories
This is a virtual zoom seminar. If you would like to attend, please email the organizers for connection details.

Dalhousie-AARMS AAMP Seminar: Reem Yassawi (Open University, London)
2020-11-06 16:00 - 17:00 (America/Halifax) | Zoom seminar
Title: Some tame or wild Cantor dynamical systems
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 .
In 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.
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.

Atlantic Graph Theory Seminar: Dr Andrea Burgess (University of New Brunswick, Saint John)
2020-11-04 15:30 - 16:30 UTC | Zoom seminar
Equitably colourable cycle decompositions
A -colouring of a decomposition of a graph is an assignment of colours to the vertices of . A colouring is equitable if each colour is represented (as closely as possible) an equal number of times on each block, i.e. for any two colours and , the number of vertices of colour and in any given block differ by at most 1. In this talk, we give an overview of colourings of designs and cycle decompositions, and present some recent joint results with Francesca Merola on the existence of equitably 2-colourable cycle decompositions of the cocktail party graph. In particular, we give a complete existence result for equitably 2-colourable -cycle decompositions of in various cases, including that or (mod ); is a power of 2; for a prime power; or .
The Atlantic Graph Theory Seminar series will take place every Wednesday from 3:30-4:30 ADT online via zoom. The talks, provided by researchers, postdocs and graduate students, will be on a variety of current topics in graph theory. If you would like to give a talk or attend, please email one of the organizers (Jason Brown and Danielle Cox).

Dalhousie-AARMS AAMP Seminar: Jean-Pierre Garbardo (McMaster University)
2020-10-30 16:00 - 17:00 (America/Halifax) | Zoom seminar
Title: Factorization of positive definite functions through convolution and the Turàn problem
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 .
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.

Atlantic Graph Theory Seminar: Iain Beaton (PhD Candidate, Dalhousie University)
2020-10-28 15:30 - 16:30 UTC | Zoom seminar
The Average Order of Dominating Sets of a Graph
This talk focuses on the average order of dominating sets of a graph. We find the extremal graphs for the maximum and minimum value over all graphs on n vertices, while for trees we prove that the star minimizes the average order of dominating sets. We prove the average order of dominating sets in graphs without isolated vertices is at most 3n/4, but provide evidence that the actual upper bound is 2n/3. Finally, we show that the normalized average, while dense in [1/2,1], tends to 1/2 for almost all graphs.
The Atlantic Graph Theory Seminar series will take place every Wednesday from 3:30-4:30 ADT online via zoom. The talks, provided by researchers, postdocs and graduate students, will be on a variety of current topics in graph theory. If you would like to give a talk or attend, please email one of the organizers (Jason Brown and Danielle Cox).

Atlantic GR Seminar: Turkuler Durgut (MUN)
2020-10-28 13:00 - 14:00 (America/Halifax) | Zoom seminar
Asymptotically Anti-de Sitter Gravitational Solitons
In this talk, I will consider the stability of asymptotically anti-de Sitter gravitational solitons. These are globally stationary, asymptotically (globally) AdS spacetimes with positive energy but without horizons. I will introduce my ongoing project investigating solutions of the linear wave equation in this class of backgrounds. I will provide analytical expressions for the behavior of the scalar field near the soliton bubble and at spatial infinity. The special BPS (supersymmetric) case will then be examined as an example of a solution where stable trapping occurs. This project is joint work with Dr. Hari K. Kunduri and Dr. Robie A. Hennigar.
The Atlantic General Relativity 2020 online postdoc/student seminar series is in the tradition of the annual AGR meetings, providing a forum not only for students and postdocs to present their research and make professional contacts but also to facilitate connections and collaborations between all Atlantic Canadian relativists. The series is student-organized and includes all areas of classical and quantum gravity. Talks will occur on the last Wednesday of every month, with each session consisting of two 30 minute talks. If you would like to attend, please email the organizers for connection details.
Note: all times are Atlantic Time

Dalhousie-AARMS AAMP Seminar: Hari Kunduri (Memorial University)
2020-10-23 16:00 - 17:00 (America/Halifax) | Zoom seminar
Title: Geometric inequalities for axisymmetric black holes
Abstract: 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
standard 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.
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.

Atlantic Graph Theory Seminar: Dr. Ben Cameron (University of Guelph)
2020-10-21 15:30 - 16:30 UTC | Zoom seminar
Title: Families of graphs containing only finitely many vertex-critical graphs.
In this talk, motivated by algorithmic aspects of graph colouring, we will consider the problem of classifying vertex-critical graphs in families of graphs. We will complete a dichotomy theorem for the number of k-vertex-critical H-free graphs when H is a graph of order four. Our results also reduce the remaining open problem for graphs of all orders to two families of graphs. Toward implementing the corresponding graph colouring algorithms, we then improve upon previous research to show tight upper bounds on the order and independence number of k-vertex-critical graphs in another family of graphs, allowing for exhaustive generation of these graphs for k at most 7 . Joint work with Chính Hoàng and Joe Sawada

Dalhousie-AARMS AAMP Seminar: Julie Rowlett (Chalmers, Sweden)
2020-10-16 16:00 - 17:00 (America/Halifax) | Zoom seminar
Decisions and Disease
Do 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.
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.

Atlantic Graph Theory Seminar: David Pike (Memorial)
2020-10-14 15:30 - 16:30 (America/Halifax) | Zoom seminar
Perfect 1-Factorisations
A matching in a graph is a subset of the edge set of such that no two edges of share a vertex. A 1-factor of a graph is a matching in which every vertex of is in one of the edges of . If is a -regular graph of even order then we can ask whether admits a 1-factorisation, namely a partition of its edge set into 1-factors.
Suppose that are the 1-factors of a 1-factorisation of a -regular graph . If, for each , the union yields a Hamilton cycle in , then we say that is a perfect 1-factorisation. We will discuss some of the history and properties of 1-factorisations, including the recent discovery of a perfect 1-factorisation of .
The Atlantic Graph Theory Seminar series will take place every Wednesday from 3:30-4:30 ADT online via zoom. The talks, provided by researchers, postdocs and graduate students, will be on a variety of current topics in graph theory. If you would like to give a talk or attend, please email one of the organizers (Jason Brown and Danielle Cox).

Dalhousie-AARMS AAMP Seminar: John Toth (McGill University)
2020-10-02 16:00 - 17:00 (America/Halifax) | Zoom seminar
Title: Pointwise bounds for joint eigenfunctions of quantum completely integrable (QCI) systems
Abstract: 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.
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.

AARMS COVID-19 Seminar: Karen Phillips (Dept of Health and Wellness, PEI) and Javier Sanchez (Atlantic Veterinary College, UPEI)
2020-09-30 15:00 - 16:30 (America/Halifax) | Zoom seminar
The Covid-19 modeling experience in Prince Edward Island
Since the beginning of the COVID-19 pandemic, Atlantic Canada and particularly PEI, has experienced a low number of cases with limited community spread. This epidemiological situation has created some unique and challenging opportunities for the modelers to address the questions of interest posed by public health officers.
A simple SEIR model was developed to assess the magnitude of the consequences in terms of hospitalizations, PPE, and bed requirements under a set of scenarios that could potentially happen if community spread starts to occur in the region. The model was based on differential equations and included features such as reduction of contact rates, self isolation, contact tracing, and quarantine. It also allows assessing the impact on different testing strategies and test requirements to control the outbreak.
Also, a Bayesian model was also developed to assess the probability that the province was free of virus circulation given the testing carried out by the government.
During this seminar will discuss how the model and modeling team addressed some of the questions of interest and describe in [some] details the mathematical models developed by the team.

Dr. Karen Phillips is an Epidemiologist at the Chief Public Health Office, Prince Edward Island Department of Health and Wellness
Dr. Javier Sanchez is a Professor of Epidemiology at the Atlantic Veterinary College, University of Prince Edward Island

This is a virtual zoom seminar. If you would like to attend, please email the organizers for connection details.

Atlantic GR Seminar: Kam To Billy Chan (MUN)
2020-09-30 13:00 - 14:00 (America/Halifax) | Zoom seminar
The Reissner-Nordstrom Near Horizon Geometry is a Tangent Spacetime
The near horizon geometry (NHG) of an extremal Reissner-Nordstrom black hole is obtained in conventional global AdS coordinates and in the coordinates of the parent spacetime. Geometrical objects, specifically Killing vectors and spacetime points, are mapped from the boundary and horizon of the NHG into the parent spacetime coordinates. The outcome is that the NHG is a tangent spacetime to the extremal Reissner-Nordstrom black hole’s degenerate horizon and that the degenerate horizon does not bifurcate. A generalization is made for N-dimensional Reissner-Nordstrom black holes. This work is an extension of Sean Stotyn’s A Tale of Two Horizons.
The Atlantic General Relativity 2020 online postdoc/student seminar series is in the tradition of the annual AGR meetings, providing a forum not only for students and postdocs to present their research and make professional contacts but also to facilitate connections and collaborations between all Atlantic Canadian relativists. The series is student-organized and includes all areas of classical and quantum gravity. Talks will occur on the last Wednesday of every month, with each session consisting of two 30 minute talks. If you would like to attend, please email the organizers for connection details.

Dalhousie-AARMS AAMP Seminar: Michael Ward (UBC)
2020-09-25 16:00 - 17:00 (America/Halifax) | Zoom seminar
Synchrony and Oscillatory Dynamics for a 2-D PDE-ODE Model of Diffusion-Sensing with Small Signaling Compartments
We 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.
Joint work with Sarafa Iyaniwura (UBC) and Jia Gou (UC Riverside).
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.

AARMS COVID-19 Seminar: Amy Hurford (MUN)
2020-08-26 15:00 - 16:30 (America/Halifax) | Zoom seminar
Modelling the impact of travel restrictions on COVID-19 cases in Newfoundland and Labrador
Imported infections disproportionally contribute to coronavirus disease 2019 (COVID-19) outbreaks in regions where infection prevalence is low. On May 4th, Newfoundland and Labrador implemented travel restrictions whereby non-residents could enter NL only with exemptions. As the prevalence of COVID-19 was low at the time, it is likely that the travel restrictions substantially reduced the COVID-19 epidemic in NL. We fit a stochastic epidemic model to data describing the number of active COVID-19 cases in NL from March 14th – May 4th. We then forecast the distribution of outbreak sizes over the 9 weeks subsequent to May 4th, with and without the travel restrictions, and for physical distancing scenarios ranging from a 40% to 70% reduction in the daily contact rate relative to pre-pandemic levels. The implementation of travel restrictions in NL resulted in a 20-fold decrease in the number of cases over the subsequent 9 weeks. Assuming that physical distancing reduced the contact rate to 55% of its pre-pandemic level, the median number of cases without the travel restrictions was 19 and with the travel restrictions was 1. Using epidemic modelling, we show how the NL outbreak would have unfolded had travel restrictions not been implemented. The few COVID-19 cases reported following the implementation of travel restrictions is not evidence that the travel restrictions were unnecessary; rather our modelling shows that the travel restrictions are a plausible reason why there were few reported cases in NL in the 9-weeks after May 4th.
This is a virtual zoom seminar. If you would like to attend, please email the organizers for connection details.

Atlantic GR Seminar: Nicholas Layden (Dalhousie) and Sharmin Akhter (MUN)
2020-08-26 13:00 - 14:00 (America/Halifax) | Zoom seminar
Geometric Horizons in the Szekeres Spacetime
Nicholas Layden (Dalhousie University)
A new conjecture for geometric horizons has been introduced which may provide a potential alternative to using apparent horizons and related surfaces for analyzing the dynamics of black hole spacetimes. In particular, using two examples of black hole formation in a collapsing universe in the Szekeres spacetime, the formation, evolution, and detection of geometric horizons are shown. In addition, a function for detecting apparent horizons in the Szekeres spacetime is also considered, and it is shown that the apparent horizon in the Szekeres model, is in fact, a geometric horizon. The Cartan-Karlhede algorithm for determining local equivalences of spacetimes is used to compute an invariant frame in the Newman Penrose frame formalism, and Cartan invariants derived from the spacetime in this frame are shown to detect the geometric horizons under various conditions on the curvature tensors of the spacetime. One model for primordial black hole formation and another for galactic black hole formation are considered with non-zero cosmological constants, generalizing work published previously on these models with zero cosmological constant. Future work utilizing geometric horizons may provide benefits in gravitational wave research involving black hole mergers.
Rigidity of Marginally Outer Trapped Surfaces in RNdS Spacetime
Sharmin Akhter (Memorial University of Newfoundland)
We investigate the rigidity of MOTS in four dimensional Reissner-Nordstrom-de Sitter spacetime. This is connected to the study of the first order derivative of stability operator (and hence the second derivative of outgoing null expansion). Since the stability operator has a zero eigenvalue in our case, we use the Lyapunov-Schmidt reduction to establish rigidity.
The Atlantic General Relativity 2020 online postdoc/student seminar series is in the tradition of the annual AGR meetings, providing a forum not only for students and postdocs to present their research and make professional contacts but also to facilitate connections and collaborations between all Atlantic Canadian relativists. The series is student-organized and includes all areas of classical and quantum gravity. Talks will occur on the last Wednesday of every month, with each session consisting of two 30 minute talks. If you would like to attend, please email the organizers for connection details.

AARMS COVID-19 Seminar: Acadia Covid Modelling Group
2020-08-12 15:00 - 16:30 (America/Halifax) | Zoom seminar
Talk 1: Estimating underreporting of COVID-19 cases using fatality data
Led by Margaret Hopkins
Talk 2: Individual-based modelling of COVID-19 on the Acadia University campus with a realistic contact structure
Led by the Acadia Modelling Group
The Acadia Modelling Group consists of D. Currie, C. Hooper, M. Hopkins, R. Karsten, Y. Li, F. Mendivil, and H. Teismann. This is a virtual zoom seminar. If you would like to attend, please email the organizers for connection details.

Café Mathématique: What is a model of COVID-19?
2020-08-12 13:00 - 15:00 (America/Halifax) | Newfoundland and Labrador
Café Mathématique is a free, online public forum where anyone can learn how math underpins our understanding of the COVID-19 pandemic. Hear from a panel of experts at universities across Canada as they answer the question, “What is a model of COVID-19?”, followed by a lively discussion where audience members are encouraged to ask questions and explore ideas about modelling the pandemic.
Panelists:

Javier Sanchez, Associate Professor, Epidemiology, University of Prince Edward Island
David Buckeridge, Professor, Epidemiology, Biostatistics & Occupational Health, McGill University
Ashleigh Tuite, Assistant Professor, Dalla Lana School of Public Health, University of Toronto
Caroline Colijn, Professor and Canada 150 Research Chair, Mathematics, Simon Fraser University

Moderators:

Jane Heffernan, Professor, Mathematics and Statistics, York University
Jude Kong, Assistant Professor, Mathematics and Statistics, York University

Register at http://www.fields.utoronto.ca/activities/20-21/cafe-math-covid

PIMS/AARMS WORKSHOP ON New Trends in Localized Patterns in PDEs
2020-08-10 - 2020-08-14 | PIMS at UBC and SFU, Vancouver, British Columbia, Canada
Mathematical Theory and Applications to Physics, Biology and the Social Sciences– a Conference in Honour of the 60th Birthday of Michael J. Ward
Localized spatial-temporal patterns commonly occur for various classes of linear and nonlinear diffusive processes. In particular, they occur in reaction-diffusion (RD) systems modeling quorumsensing (QS) behavior in biological systems, the initiation of root-hair tip formation in plant cells, and the spatial distribution of urban crime. Localization behavior also occurs in the biophysical context of calculating first passage statistics for a Brownian walker in a region with localized traps, and in ecology for calculating the persistence threshold of a species in a patchy landscape. In recent years, we have witnessed an explosion of many new and exciting developments in the theory and applications of localized solutions in PDEs. Many new frontiers have opened while new connections between old fields have been discovered.
This workshop will highlight Prof. Ward’s influential contributions to the mathematics and applications of localized solutions to PDEs. It brings together his students, colleagues and collaborators in a celebration of Prof. Ward’s 60th birthday. Over his long career, Prof. Ward has made numerous invaluable contributions to many areas of applied mathematics, including fluid dynamics, metastability, reaction-diffusion equations, cell biology and pattern formation. He has supervised 13 doctoral students and also mentored numerous postdocs and undergrads.

Math Kitchen Party: organized by Connie Stewart (UNB Saint John)
2020-08-06 20:00 - 21:00 (America/Halifax) | Zoom seminar
Hierarchical linear model with power law function on transmission of COVID-19 in Italy: Modelling and regression analysis
Youtian Hao (UNB Fredericton)
COVID-19 growth data were typically collected from each region of a country, and the transmission rate usually varies in different area. By adopting a power law with exponential cutoff function into hierarchical linear model, it becomes possible to reveal the relationship between COVID-19 transmission rate and some regional level covariates of interest. A two-level hierarchical linear model is constructed, where the first level includes a PLEC function with Poisson link, and the second level incorporates parameters from level-one with regional level covariates. Modelling and regression analysis approach is implemented based on the model with Italian COVID-19 transmission data.
Why Most Published Research Findings Are False
Hugh Chipman (Acadia)
Many scientific studies declare a “statistically significant” result but then can’t be replicated. What’s going on? Can we no longer trust statistics? Is this the end of the world as we know it?
Musical Guests

Michele Millar (MSVU)
Augusto Suarez Garcia (UNBSJ)

This is a virtual zoom meeting. If you would like to attend, please email the organizers for connection details.
[more information about the Math Kitchen Party summer talk series]

AARMS COVID-19 Seminar: James Watmough (UNB Fredericton)
2020-08-05 15:00 - 16:30 (America/Halifax) | Zoom seminar
Simple epidemic models with importation
Many provinces and territories have controlled the spread of SARS-COV-2 within their borders and are now weighing the risks and benefits of reopening internally and externally. In this week’s seminar I’ll lay out some groundwork for this comparison using variations on the simple SIR model.
This is a virtual zoom seminar. If you would like to attend, please email the organizers for connection details.

Diversity in Mathematics 2020
2020-08-04 - 2020-08-14 | Vancouver
We propose a multi-year, multi-level approach to promoting diversity and inclusivity in STEM. The annual two-week program encompasses concurrent, partially overlapping events targeting two distinct groups:
(a) A summer school for top undergraduate women in Canada and the northwest United States, specializing in mathematics or a related STEM field such as computer science, physics and statistics. The program will expose them to the many facets of the mathematical sciences in an intense two week immersion. Career opportunities in academia and industry will be given equal emphasis. We hope to encourage these gifted young women to continue on to graduate school, an arena where women are still seriously under-represented.
(b) An interactive math camp that runs as a companion program to the summer school. The target demographic here involves high school students in grades 10 and 11, irrespective of gender, with an aptitude for science and mathematics but from under-privileged groups.

Atlantic GR Seminar: Sharmila Gunasekaran Gnanam (MUN) and Robert Santacruz (UNB)
2020-07-29 13:00 - 14:00 (America/Halifax) | Zoom seminar
Slow decay of waves in gravitational solitons
Sharmila Gunasekaran Gnanam
Memorial University of Newfoundland
Gravitational solitons are globally stationary horizonless asymptotically flat spacetimes. In this talk, I will describe the methodology used to prove that massless scalar waves in a particular family of soliton spacetimes decay very slowly. The proof involves the construction of quasimodes which are approximate solutions to the wave equation. This slow decay can be attributed to the stable trapping of null geodesics and is suggestive of instability at the nonlinear level. This is joint work with Hari Kunduri.
Quantizing gravity is not that hard if you know how: An undergraduate guide to black holes
Robert Santacruz
University of New Brunswick
It is expected that singularities appearing in GR are to be resolved in a theory of Quantum Gravity. In the context of Loop Quantum Gravity, the Big Bang singularity is replaced by a bounce and so one would assume that this can be translated into Black Holes. In this talk I will explain you how to find an effective model for Schwarzschild black hole by using Loop Quantum Cosmology techniques and, the best part is, you only need Hamiltonian Mechanics!!
The Atlantic General Relativity 2020 online postdoc/student seminar series is in the tradition of the annual AGR meetings, providing a forum not only for students and postdocs to present their research and make professional contacts but also to facilitate connections and collaborations between all Atlantic Canadian relativists. The series is student-organized and includes all areas of classical and quantum gravity. Talks will occur on the last Wednesday of every month, with each session consisting of two 30 minute talks. If you would like to attend, please email the organizers for connection details.

Math Kitchen Party: organized by Asmita Sodhi (Dalhousie) and Rebecca McKay (UNB Saint John)
2020-07-23 20:00 - 21:00 (America/Halifax) | Zoom seminar
Tips and Tricks for Online Teaching
Rebecca McKay (UNB Saint John)
Many of us will be teaching with some online component in Fall 2020. In this brief talk, I will outline some tips and tricks for moving mathematics and statistics course activities into the virtual environment.
Open Discussion Session: 8:30-8:50
This is a virtual zoom meeting. If you would like to attend, please email the organizers for connection details.
[more information about the Math Kitchen Party summer talk series]

Math Kitchen Party: organized by Danielle Cox (Mount Saint Vincent)
2020-07-16 20:00 - 21:00 (America/Halifax) | Zoom seminar
Modelling correlated count data-can I delete the zeroes?
Gary Sneddon (Mount Saint Vincent)
Correlated count data with excess zeroes arise in a number of applications. We will discuss 3 motivating examples, and some approaches to modelling these type of data. Covid-19 may be mentioned, so be prepared. This is joint work with Tariqul Hasan and Renjun Ma of UNB (Fredericton).
The Shooter’s Hill Decorative Tiles: Combinatorics as Art
Karyn McLellan (Mount Saint Vincent)
This talk will explore some of the art and mathematics inspired by a mistakenly (?) placed stone tile on a terraced house in London. A set of 70 Truchet-type tiles are the building blocks for various art pieces, including an inkle loom weaving. In particular, we are interested in whether or not we can weave an overlapping strip containing all 70 tiles exactly once, and if so, how many such strips exist. Other combinatorial properties of the tiles are examined as well. Joint work with Eva Knoll(UQAM) and Danielle Cox (MSVU).
Musical Guests

Sean & Tessa Sneddon

This is a virtual zoom meeting. If you would like to attend, please email the organizers for connection details.
[more information about the Math Kitchen Party summer talk series]

AARMS COVID-19 Seminar: Sana Jahedi (UNB) and James A. Yorke (Maryland)
2020-07-15 15:00 - 16:30 (America/Halifax) | Zoom seminar
When the best pandemic models are the simplest
As a pandemic of coronavirus spreads across the globe, people debate policies to mitigate its severity.
Many complex, highly detailed models have been developed to help policy setters make better decisions. However, the basis of these models is unlikely to be understood by non-experts.
We describe the advantages of simple models for covid-19. We say a model is “simple’’ if its only parameter is the rate of contact between people in the population. Such models can be understood by a broad audience, and thus can be helpful in explaining the policy decisions to the public. They can be used to evaluate outcomes of different policy strategies. However, simple models have a disadvantage when dealing with inhomogeneous populations.
To augment the power of a simple model to evaluate complicated situations, we add what we call “satellite’’ equations that do not change the original model.
To compare simple models with complex models, we introduce our “slightly complex’’ Model J. We find the conclusions of simple and complex models can be quite similar. But, for each added complexity, a modeler may have to choose additional parameter values for which there is often little rationale but that can have a big impact on predictions. Our simulations suggest that the added complexity offers little predictive advantage.
This is a virtual zoom seminar. If you would like to attend, please email the organizers for connection details.

CMS COVID-19 Research and Education Meeting (CCREM)
2020-07-13 - 2020-07-16 | Virtual Meeting
The CMS had to postpone the 2020 CMS Summer Meeting planned for this June due to the COVID-19 pandemic. Since we cannot hold a meeting in person, the CMS still wants to provide a virtual platform for mathematicians to come together and learn during this difficult time. We feel that a meeting focused on the changes caused by COVID-19 to the way we plan, teach and do research would be of great benefit to the Canadian mathematical community.
The session will cover NSERC’s response to the COVID-19 pandemic including new funding opportunities for researchers, changes in policies for NSERC Discovery grants and scholarship and fellowship programs. NSERC staff will also be answering questions regarding the coming Discovery grant competition.
