Note 3 - Basis of Presentation and Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2020

Notes Tables

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

	March 31, 2020
	(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents	$	9,916,053	$	—	$	—

	December 31, 2019
	(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents	$	14,006,193	$	—	$	—

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	March 31,
	2020		2019
Common stock warrants		21,261,070		2,087,012
Stock options		1,182,629		256,057
Unvested restricted stock awards		98,100		—
		22,541,799		2,343,069