Note 11 - Income Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Tax at federal statutory rate	$ (4,084)	$ (5,787)
State taxes, net of federal benefit	(1,022)	(1,023)
Permanent differences	97	228
Change in valuation allowance	5,205	6,582
Research credits	(192)
Other	(4)
Provision for taxes

Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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