Mathematica Biosciences an international journal Volume 133 MICHAEL J. CHAPPELL (Coventry, England) Structural Identifiability of Models Characterizing Saturable Binding: Comparison of Pseudo-Steady-State and Non-Pseudo-Steady-State Model Formulations FRANK M. J. VAN DER LINDEN (Eindhoven, Holland) Creating Phyllotaxis: The Stack-and-Drag Model LAURENT CLARET AND ATHANASSIOS ILIADIS (Marseille Cedex, France) Nonparametric Density Estimation Applied to Population Pharmacokinetics J. D. H. SMITH (Ames, Iowa) Competition and the Canonical Ensemble COLLEEN KELLY (Kingston, Rhode Island) AND JOHN RICE (Berkeley, California) Modeling Nucleotide Evolution: A Heterogeneous Rate Analysis SHIN-HO CHUNG AND RODNEY A. KENNEDY (Canberra, Australia) Coupled Markov Chain Model: Characterization of Membrane Channel Currents with Multiple Conductance Sublevels as Partially Coupled Elementary Pores DIANA MARIA THOMAS, TERRY WAYNE SNELL, AND SAYED MURTAZA JAFFAR (Atlanta, Georgia) A Control Problem in a Polluted Environment MIRJAM KRETZSCHMAR (Bilthoven, The Netherlands), AND MARTINA Morris (New York, New York) Measures of Concurrency in Networks and the Spread of Infectious Disease A. G. RIGAS (Xanthi, Greece) Estimation of Certain Parameters of a Stationary Hybrid Process Involving a Time Series and a Point Process VOLUME CONTENTS Elsevier