报告人：阮世贵 （The University of Miami,华东师范大学客座教授）
时间：2008年12月30日（星期二）下午1：30-2:30
地点：数学楼102报告厅

Title: Hopf Bifurcation in Age Structured Models with Application to Influenza A Drift

Abstract: Understanding the seasonal/periodic reoccurrence of influenza will be very helpful in designing successful vaccine programs and introducing public health interventions. However, the reasons for seasonal/periodic influenza epidemics are still not clear even though various explanations have been proposed. In this paper, we study an age-structured type evolutionary epidemiological model of influenza A drift, in which the
susceptible class is continually replenished because the pathogen changes genetically and immunologically from one epidemic to the next, causing previously immune hosts to become susceptible. Applying our recent established center manifold theory for semilinear equations with non-dense domain, we show that Hopf bifurcation occurs in the model. This demonstrates that the age-structured type evolutionary epidemiological model of influenza A drift has an intrinsic tendency to oscillate due to the evolutionary and/or immunological changes of the influenza viruses.
(based on joint work with Pierre Magal).

报告人简介：阮士贵（Shigui Ruan） 1992年获加拿大阿尔伯特(Alberta)大学应用数学博士学位。
1992-1994年在菲尔兹(Fields)数学所和加拿大麦克马斯特(McMaster)大学做博士后。1994-2002年在加拿大道尔豪斯(Dalhousie)大学数学与统计系先后任助理教授和副教授。从2002年起在美国迈阿密大学数学系任教授。
阮教授的研究领域是动力系统和微分方程及其在生物和医学中的应用，在国际权威期刊上发表了大量学术论文，被国际同行广泛引用。现获美国国家科学基金（NSF）和国家卫生署（NIH）资助。在10多个国际学术会议上做过大会特邀报告，在40多个学术会议或研讨会上做过邀请报告，在世界各地的60多所大学做过学术报告或讲座，组织过10多次国际学术会议和专题研讨会，合作编辑了7本论文集。