Abstract: The present disclosure is directed encoding LIDAR point cloud data. In particular, a computing system can receive point cloud data for a three-dimensional space. The computing system can generate a tree-based data structure from the point cloud data, the tree-based data structure comprising a plurality of nodes. The computing system can generate a serial representation of the tree-based data structure. The computing system can, for each respective node represented by a symbol in the serial representation: determine contextual information for the respective node, generate, using the contextual information as input to a machine-learned model, a statistical distribution associated with the respective node, and generate a compressed representation of the symbol associated with the respective node by encoding the symbol using the statistical distribution for the respective node.

Abstract: Cathodic half-cells for the electrocatalytic reduction of oxygen are disclosed. Within the half-cell, a redox catalyst containing one or more non-Pt transition metals attached to a solid support (i.e., a “heterogenized” non-Pt transition metal-containing catalyst) is separate from and not in direct contact with the cathode electrode. In use, both the cathode electrode and the redox catalyst are in contact with an electrolyte solution that also contains a redox mediator. The oxidized form of the redox mediator is reduced at the cathode electrode, and the resulting reduced form migrates to the redox catalyst, where the mediator is oxidized back to its oxidized form, while oxygen is simultaneously reduced. The oxidized form of the redox mediator then migrates back to the cathode electrode, where the process is repeated. The disclosed cathodic half-cells can be used in combination with an anode half-cell in a variety of different electrochemical cells, such as in fuel cells or in electrosynthetic cells.