Weekly Engineering Update: - New Extended Model Whitepaper: Completed. Now in review. - Horizen Sidechains: Progress with the consensus and stake delegation implementation strategy. Identified how to design the delegation transaction, how the delegated stake pool will calculate its eligibility and provide proof if selected. This topic also covers the VRF design, which is being implemented as well. - Horizen mainchain updates required sidechain model: Continuing the developments for the required changes to allow backward transfers from sidechains to mainchain, creating python tests for code and functions coverage. The first code review will be performed in the first part of January. - Block Explorer update related activities: Decided which path to take to fix the existing issues and to update the block explorer to the latest version. Began updates to the block explorer. - Sphere by Horizen: Reproduce the performance issue, identified one of the possible causes of it, implemented a possible solution, possible solution now being tested.