1,721,028 research outputs found
An effective automatic procedure for testing parameter identifiability of HIV/AIDS models.
No full textRealistic HIV models tend to be rather complex and many recent models proposed in the literature could not yet be analyzed by traditional identifiability testing techniques. In this paper, we check a priori global identifiability of some of these nonlinear HIV models taken from the recent literature, by using a differential algebra algorithm based on previous work of the author. The algorithm is implemented in a software tool, called DAISY (Differential Algebra for Identifiability of SYstems), which has been recently released (DAISY is freely available on the web site http://www.dei.unipd.it/~pia/ ). The software can be used to automatically check global identifiability of (linear and) nonlinear models described by polynomial or rational differential equations, thus providing a general and reliable tool to test global identifiability of several HIV models proposed in the literature. It can be used by researchers with a minimum of mathematical background
Accessible pool and system parameters: assumptions and models.
No full textQuantitative assessment of substrate metabolism from in vivo tracer kinetic data requires a model of the system, i.e., a hypothesis on the structure and functioning of the system. Some fundamentals of modeling important for studying intermediary metabolism in the steady state will be discussed. Accessible pool and system parameters are defined. Although the calculation of accessible pool parameters is structure-free, that of system parameters requires the use of non-compartmental or compartmental structures. Assumptions, bases for choice, and relative merits of these two modeling strategies are discussed. Glucose and leucine metabolism serve as prototypes to illustrate the theoretical points
Domain of validity of classical models of leucine metabolism assessed by compartmental modeling
No full textQualitative experiment design in physiological system identification
No full textA qualitative experiment design problem for identifying compartmental models of physiological systems from multi-input-multi-output tracer experiments is examined. Qualitative experiment design consists of selecting the sites of inputs and outputs, among those experimentally feasible, which guarantee a priori unique identifiability of model parameters. Using this method, a minimal input-output configuration that ensures a priori unique identifiability is defined. The problem is of practical relevance when dealing with physiological systems in which severe constraints exist on experiment design for both ethical and practical reasons. Fundamentals of physiological systems, tracer experiments, compartmental models, and a priori identifiability are discussed. As a case study, a ten-compartment model of leucine metabolism and the multi-input-output tracer experiment designed for its identification are described
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