Xinzhi Liu is Associate Professor of Applied Mathematicsnat the Univerity of Waterloo, Ontario, Canada. The author or coauthor of over 60 professional papers and one monograph, Dr. Liu is a a member of the American Mathematical Soceity and thr Canadian Applied Mathematical Society. He received the B.Sc. degree (1982) in mathematics from Shandong Normal University, the People's Republic of China, and the M.sc.(1987) and Ph.D (1988) degrees in mathematical science from the University of Texas at Arlington. David Siegel is Associate Professor of Applied mathematics at the University of Waterloo, Ontario, Canada. The author or coauthor of over 20 professional papers, Dr. Siegel is a member of the American Mathematical Society and the Canadian Applied Mathematics Society. He received the B.A. degree(1973) in mathematics from the University of California, Los Angeles, and the M.S.(1976) and the Ph.D. (1978) degrees in mathematics from Stanford University, California.

• On 2-Layer Free-Boundary Problems with Generalized Joining Conditions: Convexity and Successive Approximation of Solutions. Nonisothermal Semiconductor Systems. A Model for the Growth of the Subpopulation of Lawyers. Differential Inequalities and Existence Theory for Differential, Integral and Delay Equations. Monotone Iterative Algorithms for Coupled Systems of Nonlinear Parabolic Boundary Value Problems. Steady-State Bifurcation Hypersurfaces of Chemical Mechanisms. Stability Problems for Volterra Functional Differential Equations. Persistance (Permanence), Compressivity and Practical Persistance in Some Reaction-Diffusion Models from Ecology. Perturbing Vector Lyapunov Functions and Applications. On the Existence of Multiple Positive Solutions of Nonlinear Boundary Value Problems. Gradient and Gauss Curvature Bounds for H-Graphs. Some Applications of Geometry to Mechanics. Comparison of Even-Order Elliptic Equations. Positive Equilibria and Convergence in Subhomogeneous Monotone Dynamics. On the Existence of Extremal Solutions for Impulsive Differential Equations with Variable Time. Global Asymptotic Stability of Competitive Neural Networks. A Graph Theoretical Approach to Monotonicity with Respects to Initial Conditions. Set-Valued Techniques for Viability and Stabilization of Uncertain Systems. The Relationship Between the Boundary Behavior of and the Comparison Principals Satisfied by Approximate Solutions of Elliptic Dirichlet Problems. Comparison Principle for Impulsive Differential Equations with Variable Times.