Abraham Mendel Theben convinced this ruler to offer limited protections to Jews. This ruler appears on the obverse of a namesake silver bullion thaler which was circulated for over two centuries. Wenzel Anton von Kaunitz was state chancellor and foreign minister to this ruler, during whose reign the physician Gerard van Swieten was sent to Moravia to investigate the existence of vampires. Charles 
Abraham Mendel Theben convinced this ruler to offer limited protections to Jews. This ruler appears on the obverse of a namesake silver bullion thaler which was circulated for over two centuries. Wenzel Anton von Kaunitz was state chancellor and foreign minister to this ruler, during whose reign the physician Gerard van Swieten was sent to Moravia to investigate the existence of vampires. Charles (*) VI's flagrant disregard for Salic law resulted in this ruler taking the throne. After this ruler's death, her country underwent a decade of temporary reform under her son Joseph II. The Pragmatic Sanction attempted to legitimate the rule of this queen, who lost the region of Silesia to Frederick the Great. For 10 points, name this 18th-century queen of Austria.