  Emergent properties such as nuclear saturation and deformation, and the
effects on shell structure due to the proximity of the scattering continuum and
particle decay channels are fascinating phenomena in atomic nuclei. In recent
years, ab initio approaches to nuclei have taken the first steps towards
tackling the computational challenge of describing these phenomena from
Hamiltonians with microscopic degrees of freedom. This endeavor is now possible
due to ideas from effective field theories, novel optimization strategies for
nuclear interactions, ab initio methods exhibiting a soft scaling with mass
number, and ever-increasing computational power. This paper reviews some of the
recent accomplishments. We also present new results. The recently optimized
chiral interaction NNLO$_{\rm sat}$ is shown to provide an accurate description
of both charge radii and binding energies in selected light- and medium-mass
nuclei up to $^{56}$Ni. We derive an efficient scheme for including continuum
effects in coupled-cluster computations of nuclei based on chiral
nucleon-nucleon and three-nucleon forces, and present new results for unbound
states in the neutron-rich isotopes of oxygen and calcium. The coupling to the
continuum impacts the energies of the $J^\pi = {1/2}^-,{3/2}^-,{7/2}^-,{3/2}^+$
states in $^{17,23,25}$O, and - contrary to naive shell-model expectations -
the level ordering of the $J^\pi = {3/2}^+,{5/2}^+,{9/2}^+$ states in
$^{53,55,61}$Ca.
