  The momentum, fermionic density, spin density, and interaction dependencies
of the exponents that control the (momentum-energy)-plane singular features of
the one-fermion spectral functions of a one-dimensional gas of spin-1/2
fermions with repulsive delta-function interaction both at zero and finite
magnetic field are studied in detail. Our results refer to energy scales beyond
the reach of the low-energy Tomonaga-Luttinger liquid and rely on the
pseudofermion dynamical theory for integrable models. The one-fermion spectral
weight distributions associated with the spectral functions studied in this
paper may be observed in systems of spin-1/2 ultra-cold fermionic atoms in
optical lattices.
