Today in 2007, US Patent 7244458 B1 was issued, an invention of Simon Daniel Scullion, Peter Thomas Foster, and Stephen Paul Smith, assigned to Coors European Properties Gmbh, for their “Method of Cooling a Draught Alcoholic Beverage in a Vessel.” Here’s the Abstract:

A draught beverage which may be alcoholic or non-alcoholic, for example a lager or cider in an open-topped drinking vessel or glass. The beverage comprises a water content and dissolved gas content. The draught beverage is dispensed from a font at a cooled temperature below the freezing point of water at ambient atmospheric pressure. The dispense temperature may be in the range of −1° C. to −12° C. The beverage in the glass may or may not be subjected to external excitement energy, for example ultra-sound, to encourage formation of nucleation sites in the beverage. Either way dissolved gas bubbles out of the beverage causing occurrence of nucleation sites at which ice from the water content forms. At least in part the ice has a slushy character. A head also forms on the dispensed draught beverage and below the head the ice locates and develops downwards into the beverage.