Distinguished Lectures

DISTINGUISHED LECTURE: Modeling and Analyzing Information Propagation Dynamics in the Chinese Social Network Sina-Microblog

Abstract: As the largest social media in China, Sina-Microblog plays an important role in public opinion dissemination. Despite intensive efforts in understanding the information propagation dynamics, the use of a simple outbreak model to generate summative indices that can be used to characterize the time series of single information or cross-information being forwarded in the network has not been attempted yet. We have been developing a framework based on susceptible-forwarding-immune (SFI) models and a crosstransmission susceptible-forwarding-immune (CT-SFI) models to fill this gap. Our progress has illustrated the significant potential of using an outbreak model in conjunction with historical data on cumulative forwarding users to study the law of information propagation in social media.

Dr. Fulian Yin
Professor
Communication University of China

Date: March 19, 2021
Time: 9:00-10:00 AM
Location: Zoom – link: https://yorku.zoom.us/j/96643509945

DISTINGUISHED LECTURE: Cost and social distancing dynamics in a mathematical model of COVID-19

Abstract: We present an SEIAR mathematical model of COVID-19 which includes social distancing and relaxation. Our model has a dynamic behavioural influence where the decision for susceptible people to isolate is a function of the total and active cases, but the decision to stop isolating is a function of the perceived cost of isolation. Along with this social distancing cost, we define an overburden healthcare cost due to the strain placed on the healthcare system with a high caseload. We demonstrate that, non-intuitively, increasing either isolation activity or incentive to isolate do not always lead to optimal health outcomes.

Dr. Iain Moyles
Professor
York University

Date: March 12, 2021
Time: 9:00-10:00 AM
Location: Zoom – link: https://yorku.zoom.us/j/96643509945

 

DISTINGUISHED LECTURE: Unpredicted outbreak by the basic reproduction number

Abstract: Time-varying individual host susceptibility to a disease due to waning and boosting of immunity is known to induce rich long-term behavior of the disease transmission dynamics. Simultaneously, the impact of the time-varying heterogeneity of host susceptibility on the short-term behavior of epidemics is not well-studied despite the availability of a large amount of epidemiological data on short-term epidemics. This paper proposes a parsimonious mathematical model describing the short-term transmission dynamics by taking into account waning and enhancing susceptibility following the infection. In addition to the common classification in the standard SIR model, i.e., “no epidemic” as R0 < 1 or normal epidemic as R0 > 1, the proposed model also shows the “delayed epidemic” class when an epidemic takes off after the negative slope of the epidemic curve at the initial phase of the epidemic. The condition for each of the three classes is derived based on the obtained explicit solution for the proposed model. We also confirmed that the variation of susceptibility at individual level following the infection induces “delayed epidemic”.

Dr. Ryosuke Omori
Professor
Hokkaido University

Date: March 4, 2019
Time: 11:30 AM - 12:30 PM
Location: Kinsmen 277

DISTINGUISHED LECTURE: A Delayed Reaction-Diffusion Equation with Free Boundary

Abstract: Incorporating time delay and Stefan type free boundary into reaction-diffusion equation yields a compatible condition, which guarantees the well-posedness of the initial value problem. Further, under a KPP type setting we establish a dichotomy on propagation or vanishing. When propagation happens, the spreading speed is shown to exist and it is determined nonlinearly by a delay-induced nonlocal elliptic problem in half line. This talk is based on a joint work with Dr. Ningkui Sun.

Dr. Jian Fang
Professor
Harbin Institute of Technology

Date: February 19, 2019
Time: 12:00 PM - 1:00 PM
Location: Kinsmen 277

 

DISTINGUISHED LECTURE: Nonlinear Boundary Value Problems in Ordered Banach Spaces

Abstract: In proving existence of positive solutions for nonlinear boundary value problems, properly constructions of the cones that define the order of the Banach spaces are essential. We will introduce a new class of order- cones that can be used to prove existence of fixed points for nonlinear and semilinear operators on order intervals.
The abstract results unified previous methods in various spaces. When they are applied to concrete cases such as nonlinear algebraic systems, Dirichlet boundary value problem and fractional differential equations, new results can be naturally obtained. Applications will be shown by examples. We will also briefly discuss other topological methods in studying existences and multiplicity of solutions for nonlinear and semilunar boundary value problems.

Dr. Wenying Feng
Professor
Trent University

Date: October 5, 2018
Time: 12:30 PM - 1:30 PM
Location: Kinsmen 277

DISTINGUISHED LECTURE: Travel Frequency and Infectious Diseases

Abstract: Empirical and statistical evidences suggest that the number of trips taken per year varies significantly among people by age, gender, income, occupation, ethnicity, region and so on. Only a small fraction of people are frequent travelers while most travel occasionally or never. To take the difference in travel frequency into consideration, we propose a multipatch epidemic model where humans in each patch are divided into susceptible occasional, infectious occasional, susceptible frequent, and infectious frequent travelers. The basic reproduction number 0 is derived which completely governs the global dynamics of the model system. Lower and upper bounds of the single and multiple patch reproduction numbers are given and the disease can become endemic or extinct even though it dies out or persist in each isolated patch. Both analytical and numerical approaches show that the model without distinguishing the difference in travel frequency tends to underestimate the infection risk. Several numerical examples are presented to illustrate the impact of changes in modern travel on disease spread.

Dr. Daozhou Gao
Professor
Shanghai Normal University

Date: August 10, 2018
Time: 10:30 AM - 11:30 AM
Location: Kinsmen 277

DISTINGUISHED LECTURE: Dispersal Heterogeneity and the Spreading Speeds of Marine Invasions

Abstract: We propose a structured integro-difference equation model for an invasive marine species with a pelagic larval stage and examine the role of dispersal heterogeniety on the spreading speed. The spread of the green crab up the northwest coast of the Atlantic is used as a case study. We find that the relationship between spreading speed and demographic and dispersal parameters is similar to the relationship found in Fisher's equation. We also find that temporal variation in dispersal results in a faster spread rate than predicted by a time-averaged dispersal kernel. This is joint work with Lin Wang, Myriam Barbeau and Ali Gharouni.

Dr. James Watmough
Professor
University of New Brunswick

Date: March 20, 2018
Time: 10:30 AM to 11:30 PM
Location: Kinsmen 277

 

DISTINGUISHED LECTURE: Diffusive Host-Pathogen System with Different Dispersal Rates and Spatial Heterogeneity

Abstract: We will demonstrate some recent results on a diffusive host-pathogen model with spatially heterogeneous parameters and distinct dispersal rates for the susceptible and infected hosts. In addition to global existence of solution, existence of a global attractor, we also discuss the threshold dynamics in terms of the basic reproduction number R_0 which is identified as the spectral radius of a linear operator in the appropriate functions space. When R_0>1, the solution of the model is uniformly persistent and there exists a positive steady state. In the latter case, we also explore the asymptotic profiles of the endemic steady state as the dispersal rate of the susceptible or infected hosts approaches zero. The results reveal some differences between the roles that the dispersion of susceptible and infectious hosts can play.

Dr. Xingfu Zou
Professor
University of Western, Ontario

Date: April 24, 2017
Time: 2:30 P.M to 3:30 P.M
Location: CB 126

DISTINGUISHED LECTURE: Novel Principles and Approaches of Bioinformation Acquisition at the Nanoscale and Molecular Level

Abstract: This talk gives a systematic review of the pioneering research in bioinformation acquisition at the nanoscale and molecular level, developed at the Key Laboratory for Bio-Nanotechnology and Molecular Engineering of Hunan Province. It focuses on challenges of this development for bioinformatics and complex data analytics.

Dr. Kemin Wang
Professor
Hunan University, China

Date: October 11, 2016
Time: 11:30 to 12:30 am
Location: CB 126

DISTINGUISHED LECTURE: Transmission Dynamics and Final Epidemic Size of Ebola Virus Disease Outbreaks with Varying
Interventions

Abstract: The 2014 Ebola Virus Disease (EVD) outbreak in West Africa was the largest and longest ever reported since the first identification of this disease. We propose a compartmental mode for EVD dynamics, including virus transmission in the community, at hospitals, and at funerals. Using time-dependent parameters, we incorporate the increasing intensity of intervention efforts. Fitting the system to the early phase of the 2014 West Africa Ebola outbreak, we estimate the basic reproduction number as 1.44. We derive a final size relation which allows us to forecast the total number of cases during the outbreak when effective interventions are in place. Our model predictions show that, as long as cases are reported in any country, intervention strategies cannot be dismissed. Since the main driver in the current slowdown of the epidemic is not the depletion of susceptibles, future waves of infection might be possible, if control measures or population behavior are relaxed. By comparing model output to real data, we show that the model can provide very accurate predictions even when intervention parameters are time-varying.

Dr. Gergely Röst
Professor
University of Szeged, Szeged, Hungary

Date: September 30, 2015
Time: 3:30 pm to 4:00 pm
Location: TEL 5021A

DISTINGUISHED LECTURE: Traveling Waves in Isothermal Diffusion Systems: Existence, Stability and Oscillations

Abstract: In this talk I shall present some of the most recent results my and collaborators and I have proved in the last a few years. In particular, we show a promising model proposed by a leading world authority in chemical engineering, Prof. Gary of U. Cambridge, FRS, has very rich structures and the analytic study proves to be far more challenge than the old model.

Dr. Yuanwei Qi
Professor
University of Central Florida, Florida, USA

Date: September 30, 2015
Time: 4:00 pm to 4:30 pm
Location: TEL 5021A

DISTINGUISHED LECTURE: Mad Cow Disease: How Collaboration Between Biologists and Mathematicians Lead to a New Discovery About Prion Formation

Abstract: In a previous work by Alvarez-Martinez et al. (2011), the authors pointed out some fallacies in the mainstream interpretation of the prion amyloid formation. It appeared necessary to propose an original hypothesis able to reconcile the in vitro data with the predictions of a mathematical model describing the problem. During this talk, I will introduce a model developed accordingly with the hypothesis that an intermediate on-pathway leads to the conformation of the prion protein into an amyloid competent isoform thanks to a structure, called micelles, formed from hydrodynamic interaction. I will also compare data to the prediction of our model and propose a new hypothesis for the formation of infectious prion amyloids.

Dr. Laurent Pujo-Manjouet
Associate Professor
Université Clude Bernard, Lyon, France

Date: September 1st, 2015
Time: 2:30 pm to 3:30 pm
Location: Ross N940

DISTINGUISHED LECTURE: The Information System Approach Towards Big Data Processing and Analysis

Abstract: A group of four scientists from the College of Information System and Management (CISM) at the National University of Defense Technology (NUDT) will introduce their recent research findings and the training and research capacity at NUDT, to furtheren exploration of collaborative opportunities between LIAM and CISM. They share common research interest in the discipline of Management Science and Engineering (MSE), and their research expertise in the fields of information system approach towards big data and cloud computing includes supporting information technologies; data analytics and design technologies; methodologies for information system management; and information systems analytics and design for special applications. The group will discuss their perspective on potential collaboration with LIAM and York’s ADERSIM group in crisis management using big data and cloud computing based simulation.

Dr. Weidong Bao
Professor
College of Information System and Management, National University of Defense Technology, Changsha, China
Dr. Jiuyang Tang
Professor
College of Information System and Management, National University of Defense Technology, Changsha, China
Dr. Yaohong Zhang
Associate Professor
College of Information System and Management, National University of Defense Technology, Changsha, China
Dr. Zhimeng Li
Associate Professor
College of Information System and Management, National University of Defense Technology, Changsha, China

Date: August 21, 2015
Time: 10:30 am to 11:30 pm
Location: Ross N638