Quantum plasticity and supersolid response in helium-4

We argue that the three key phenomena recently observed in solid super(4)He-mass supertransport, anomalous isochoric compressibility (syringe effect), and giant plasticity-are closely linked to each other through the physics of an interconnected network of tilted quantum-rough dislocations. As immediate implications of this connection several predictions follow: In the absence of super(3)He impurities, the syringe effect and giant plasticity persist down to T = 0; the dynamical low-frequency syringe and giant-plasticity responses are dispersionless; and similarly to giant plasticity but without direct relationship to the supertransport along the dislocation cores, super(3)He impurities should suppress the syringe effect partially or completely at appropriately low temperatures.