  We study the linear conductance through a double-quantum-dot system
consisting of an interacting dot in its Kondo regime and an effectively
noninteracting dot, connected in parallel to metallic leads. Signatures in the
zero-bias conductance at temperatures $T>0$ mark a pair of quantum (T=0) phase
transitions between a Kondo-screened many-body ground state and non-Kondo
ground states. Notably, the conductance features become more prominent with
increasing $T$, which enhances the experimental prospects for accessing the
quantum-critical region through tuning of gate voltages in a single device.
