Function to set up a kinetic model with one or more state variables

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Description

The function usually takes several expressions, each assigning a compound name to a list, specifying the kinetic model type and reaction or transfer to other observed compartments. Instead of specifying several expressions, a list of lists can be given in the speclist argument.

For the definition of model types and their parameters, the equations given in the FOCUS and NAFTA guidance documents are used.

Usage

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mkinmod(..., use_of_ff = "min", speclist = NULL, quiet = FALSE, verbose = FALSE)

Arguments

...

For each observed variable, a list has to be specified as an argument, containing at least a component type, specifying the type of kinetics to use for the variable. Currently, single first order kinetics "SFO", indeterminate order rate equation kinetics "IORE", or single first order with reversible binding "SFORB" are implemented for all variables, while "FOMC", "DFOP" and "HS" can additionally be chosen for the first variable which is assumed to be the source compartment. Additionally, each component of the list can include a character vector to, specifying names of variables to which a transfer is to be assumed in the model. If the argument use_of_ff is set to "min" (default) and the model for the compartment is "SFO" or "SFORB", an additional component of the list can be "sink=FALSE" effectively fixing the flux to sink to zero.

use_of_ff

Specification of the use of formation fractions in the model equations and, if applicable, the coefficient matrix. If "min", a minimum use of formation fractions is made in order to avoid fitting the product of formation fractions and rate constants. If "max", formation fractions are always used.

speclist

The specification of the observed variables and their submodel types and pathways can be given as a single list using this argument. Default is NULL.

quiet

Should messages be suppressed?

verbose

If TRUE, passed to cfunction if applicable to give detailed information about the C function being built.

Value

A list of class mkinmod for use with mkinfit, containing

diffs

A vector of string representations of differential equations, one for each modelling variable.

parms

A vector of parameter names occurring in the differential equations.

map

A list containing named character vectors for each observed variable, specifying the modelling variables by which it is represented.

use_of_ff

The content of use_of_ff is passed on in this list component.

coefmat

The coefficient matrix, if the system of differential equations can be represented by one.

Note

The IORE submodel is not well tested (yet). When using this model for metabolites, you may want to read the second note in the help page to mkinfit.

Author(s)

Johannes Ranke

References

FOCUS (2006) “Guidance Document on Estimating Persistence and Degradation Kinetics from Environmental Fate Studies on Pesticides in EU Registration” Report of the FOCUS Work Group on Degradation Kinetics, EC Document Reference Sanco/10058/2005 version 2.0, 434 pp, http://focus.jrc.ec.europa.eu/dk

NAFTA Technical Working Group on Pesticides (not dated) Guidance for Evaluating and Calculating Degradation Kinetics in Environmental Media

Examples

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# Specify the SFO model (this is not needed any more, as we can now mkinfit("SFO", ...)
SFO <- mkinmod(parent = list(type = "SFO"))

# One parent compound, one metabolite, both single first order
SFO_SFO <- mkinmod(
  parent = mkinsub("SFO", "m1"),
  m1 = mkinsub("SFO"))

## Not run: 
# The above model used to be specified like this, before the advent of mkinsub()
SFO_SFO <- mkinmod(
  parent = list(type = "SFO", to = "m1"),
  m1 = list(type = "SFO"))

# Show details of creating the C function
SFO_SFO <- mkinmod(
  parent = mkinsub("SFO", "m1"),
  m1 = mkinsub("SFO"), verbose = TRUE)

# If we have several parallel metabolites 
# (compare tests/testthat/test_synthetic_data_for_UBA_2014.R)
m_synth_DFOP_par <- mkinmod(parent = mkinsub("DFOP", c("M1", "M2")),
                           M1 = mkinsub("SFO"),
                           M2 = mkinsub("SFO"),
                           use_of_ff = "max", quiet = TRUE)

fit_DFOP_par_c <- mkinfit(m_synth_DFOP_par, 
                          synthetic_data_for_UBA_2014[[12]]$data,
                          quiet = TRUE)

## End(Not run)

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