Note 4 - Balance Sheet Components - Accounts Receivable, Net of Allowance (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Accounts receivable	$ 35	$ 1,796
Royalty [Member]
Accounts receivable	15	1,776
Government Contract [Member]
Accounts receivable	$ 20	$ 20

Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current.

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