In this talk, I will present some of our recent work on biological systems with multiple stable states. We show that these models could exhibit multistability phenomena: (i) node-node bistability; (ii) node-cycle bistability; (iii) cycle-cycle bistability; (iv) node-node-cycle tristability and (v) node-node-torus tristability. The talk is based on joint work with Xi Hu, Hongying Shu and James Watmough.

In this talk, we propose a mathematical model for HIV infection with delays in cell infection and virus production. The model examines a viral-therapy for controlling infections through recombining HIV virus with a genetically modified virus. For this model, we derive two biologically insightful quantities (reproduction numbers) R_0 and R_z, and their threshold properties are discussed. When R_0 < 1, the infection-free equilibrium E_0 is globally asymptotically stable. If R_0 > 1 and R_z<1, the

R-M板的若干新的有限元 计算方法石钟慈教授中国科学院院士中科院计算数学研究所研究员1.学术报告时间：2015年10月15日(星期四)下午3：00-3:50地点：数学系（致远楼）107室2.关于学科建设与青年计算数学人才的培养2015年10月15日(星期四)下午4：00-4:50地点：数学系（致远楼）102室欢迎教师、研究生及有兴趣者参

标题： Steiner Systems Over vector Spaces报告人： Tuvi Etzion Department of Computer Science Technion, Israel时间： 9月24日 下午4:00-5:00地点： 致远楼10

1. Algorithm for portfolio compression of swaps. Due to regulation requirement, each trade we did has a risk weight asset (RWA) value, which determines how much money the bank has to hold. Since bank always wants to use their capital rather than just holding them, they have an incentive to reduce the RWA. From the formula for RWA, one will see that RWA for two opposite trades doubles the RWA of each one. This means if we terminate the two trades at the same time, RWA got reduced to 0, without any impact on book value or risks. This is the incentive of portfolio compression. A portfolio of swaps consists of many swaps in the same currency, but with different payment schedules and maturities. We need to find a way to terminates some of them, so that the RWA got reduced by the most, and at the same time changes in book value and risks are not big.

报告人：李先义 教授 (扬州大学)题目：Complex dynamics of a general 3D chaotic system with three negative Lyapunov coefficients时间： 9月16日（星期三），上午9:00-10:00地点：数学系致远楼102欢迎各位参加！李先义，男，扬州大学数学系教授，博士生导师；华东师范大学应用数学专业博士提前毕业（2004.1）,法国里尔科技大学数学系博士后(2005-2006)。研究方向：常微分方程与动力系统；主要研究兴趣：稳定性理论、分支与...

报告人：王玮明 教授 (温州大学)题目： A stochastic SIRS epidemic model时间： 9月16日（星期三），上午10:00-11:00地点：数学系致远楼102欢迎各位参加！王玮明，理学博士，浙江省重点学科“应用数学”学科带头人，中国生物数学会理事，浙江省“新世纪151人才工程”第二层次人选。现为温州大学数学学院教授、应用数学研究所所长。曾被评为温州大学“最受学生爱戴的老师”及“我心目中的好导师”。2013年领衔的应用数学教学团...

报告人：褚继峰 教授 (河海大学)题目： Complete Structure of the Fucik Spectrum of the p-Laplacian with Integrable Potentials时间： 9月15日（星期二），下午2:30-3:30地点：数学系致远楼102欢迎各位参加！储继峰，男，河海大学教授、博士生导师、数学系系主任。先后入选教育部“新世纪优秀人才支持计划”、江苏省第四期“333 高层次人才培养工程”、德国“洪堡学者”，曾获教育部“霍英东高校青年教师奖”、“秦元勋数学...