On some reducibility and existential interpretability of structures

We prove the embeddability of the structure of Turing degrees into the structure of degrees of existential interpretability. The notion of weakly bounded Turing reducibility ($\operatorname{wbT}$-reducibility) arises in the proof naturally. We demonstrate that this reducibility is situated strictly between the bounded truth-table reducibility and Turing reducibility and differs from the truth-table reducibility.