nlraa (version 1.9.7)

SSsharp: self start for temperature response

Description

Self starter for temperature response function

Usage

sharp(temp, r_tref, e, el, tl, eh, th, tref = 25)
SSsharp(temp, r_tref, e, el, tl, eh, th, tref = 25)

Value

sharp: vector of the same length as x using a sharp function

Arguments

temp

input vector (x) which is normally ‘temperature’.

r_tref

rate at the standardised temperature, tref

e

activation energy (eV)

el

low temperature de-activation energy (eV)

tl

temperature at which the enzyme is half active and half suppressed due to low temperatures

eh

high temperature de-activation energy (eV)

th

temperature at which enzyme is half active and half suppressed dut to high temperatures

tref

standardisation temperature in degrees centigrade. Temperature at which rates are not inactivated by either high or low temperatures. Typically, 25 degrees.

Details

For details see Schoolfield, R. M., Sharpe, P. J. & Magnuson, C. E. Non-linear regression of biological temperature-dependent rate models based on absolute reaction-rate theory. Journal of Theoretical Biology 88, 719-731 (1981)

Examples

# \donttest{
require(ggplot2)
require(minpack.lm)

temp <- 0:45
rate <- sharp(temp, 1, 0.03, 1.44, 28, 19, 44) + rnorm(length(temp), 0, 0.05)
dat <- data.frame(temp = temp, rate = rate)
## Fit model
fit <- nlsLM(rate ~ SSsharp(temp, r_tref, e, el, tl, eh, th, tref = 20), data = dat)
## Visualize
ggplot(data = dat, aes(temp, rate)) + geom_point() + geom_line(aes(y = fitted(fit)))

# }