  We present results from numerical simulations of the 2+1d SU(2)xSU(2) Nambu -
Jona-Lasinio model with N_f=4 fermion flavours at zero and nonzero temperature
T. At zero temperature, critical exponents are extracted from the scaling of
the order parameter and fermion mass and are found to be consistent with
next-to-leading order predictions of the 1/N_f expansion. At nonzero
temperature we observe fermion mass generation despite the lack of chiral
symmetry breaking, which is forbidden by the Colemann-Mermin-Wagner theorem for
all T>0. We study the effects of lattice discretisation and finite volume on
the dynamically generated fermion mass. By study of the lattice dispersion
relation we also show that in the hot phase there is no significant temperature
induced modification to the speed of light. Studies of the equation of state
are made by measuring the pressure as a function of temperature and comparison
is made with large-N_f predictions.
