Note 7 - Embedded Derivatives Liabilities (Tables)

6 Months Ended

Jun. 30, 2020

Notes Tables

Defined Benefit Plan, Assumptions [Table Text Block]

	June 30,			December 31,
	2020			2019
Stock price	$	0.79		$	2.31
Conversion Rate per $1,000		409.50			67.95
Conversion Price	$	2.44		$	14.72
Maturity date	April 1, 2021			March 15, 2020
Risk-free interest rate		0.17	%		1.52	%
Estimated stock volatility		92	%		60	%
Estimated credit spread		38	%		27	%

Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

	Issuance Date	Expiration Date	Exercise Price as of June 30, 2020		Shares Underlying Warrants on Issuance Date		Shares Issued upon Warrant Exercises as of June 30, 2020		Shares Underlying Warrants Outstanding as of June 30, 2020
Series D Warrants	12/11/2015	12/11/2020	$	40.00		25,125		25,078		47
Series F Warrants	04/01/2016	04/01/2021	$	40.00		25,733		11,692		14,041
Series I Warrants	09/13/2016	09/13/2021	$	220.00		35,368		—		35,368
Series K Warrants	02/17/2017	2/17/2022	$	3.80		310,016		308,660		1,356
						396,242		345,430		50,812