  We numerically explore electron acceleration and coronal heating by
dissipative electric fields. Electrons are traced in linear force-free magnetic
fields extrapolated from SOHO/MDI magnetograms, endowed with anomalous
resistivity ($\eta$) in localized dissipation regions where the magnetic twist
$\nabla \times \bhat$ exceeds a given threshold. Associated with $\eta > 0$ is
a parallel electric field ${\bf E} = \eta {\bf j}$ which can accelerate runaway
electrons. In order to gain observational predictions we inject electrons
inside the dissipation regions and follow them for several seconds in real
time. Precipitating electrons which leave the simulation system at height $z$ =
0 are associated with hard X rays, and electrons which escape at height $z$
$\sim$ 3$\cdot 10^4$ km are associated with normal-drifting type IIIs at the
local plasma frequency. A third, trapped, population is related to
gyrosynchrotron emission. Time profiles and spectra of all three emissions are
calculated, and their dependence on the geometric model parameters and on
$\eta$ is explored. It is found that precipitation generally preceeds escape by
fractions of a second, and that the electrons perform many visits to the
dissipation regions before leaving the simulation system. The electrons
impacting $z$ = 0 reach higher energies than the escaping ones, and
non-Maxwellian tails are observed at energies above the largest potential drop
across a single dissipation region. Impact maps at $z$ = 0 show a tendency of
the electrons to arrive at the borders of sunspots of one polarity. Although
the magnetograms used here belong to non-flaring times, so that the simulations
refer to nanoflares and `quiescent' coronal heating, it is conjectured that the
same process, on a larger scale, is responsible for solar flares.

Astrophysics