Note 7 - Loss Per Share - Shares Used in Basic and Diluted Loss Per Common Share Computations (Details) - USD ($)		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Net loss available in basic and diluted calculation		$ (3,293,184)	$ (1,760,022)
Comprehensive loss		$ (3,293,184)	$ (1,760,022)
Weighted average common shares outstanding-basic (in shares)		15,731,517	11,383,217
Effect of diluted stock options warrants and preferred stock (1) (in shares)	[1]
Weighted average common shares outstanding-basic and diluted (in shares)		15,731,517	11,383,217
Loss per common share - basic and diluted (in dollars per share)		$ (0.21)	$ (0.15)

[1] The number of shares underlying options and warrants outstanding as of March 31, 2019 and March 31, 2018 are 10,022,709 and 5,950,630, respectively. The number of shares underlying the convertible debt as of March 31, 2019 is 5,047,700. The number of shares underlying the preferred stock as of March 31, 2019 is 79,246. The effect of the shares that would be issued upon exercise of such options, warrants, convertible debt and preferred stock has been excluded from the calculation of diluted loss per share because those shares are anti-dilutive.