  The nanoflare paradigm of coronal heating has proven extremely promising for
explaining the presence of hot, multi-million degree loops in the solar corona.
In this paradigm, localized heating events supply enough energy to heat the
solar atmosphere to its observed temperatures. Rigorously modeling this
process, however, has proven difficult, since it requires an accurate treatment
of both the magnetic field dynamics and reconnection as well as the plasma's
response to magnetic perturbations. In this paper, we combine fully 3D
magnetohydrodynamic (MHD) simulations of coronal active region plasma driven by
photospheric motions with spatially-averaged, time-dependent hydrodynamic (HD)
modeling of coronal loops to obtain physically motivated observables that can
be quantitatively compared with observational measurements of active region
cores. We take the behavior of reconnected field lines from the MHD simulation
and use them to populate the HD model to obtain the thermodynamic evolution of
the plasma and subsequently the emission measure distribution. We find the that
the photospheric driving of the MHD model produces only very low-frequency
nanoflare heating which cannot account for the full range of active region core
observations as measured by the low-temperature emission measure slope.
Additionally, we calculate the spatial and temporal distributions of field
lines exhibiting collective behavior, and argue that loops occur due to random
energization occurring on clusters of adjacent field lines.
