v3.19.3
Note 8 - Warrants (Tables)
12 Months Ended
Dec. 31, 2018
Notes Tables  
Schedule of Stockholders' Equity Note, Warrants or Rights [Table Text Block]

Issuance Date

 

Expiration Date

 

Exercise Price

 

Number of Shares (in thousands)

 

November, 2015

 

November, 2025

 

0.2276

 

198

 

January, 2016

 

January, 2026

 

0.2276

 

132

 

 

 

 

 

 

 

 

 

Total

 

 

 

 

 

330

 

 

 

 

 

 

 

 

 

Warrants For Series A Convertible Preferred Stock [Member]  
Notes Tables  
Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]

 

 

 

 

 

 

 

 

 

As of December 31,

 

 

    

2017

    

2018

 

 

 

 

 

 

 

Risk-free interest rate

 

2.28

%  

2.56% – 2.59

%

Remaining contractual life (in years)

 

7.92 – 8.08

 

6.92 – 7.08

 

Dividend yield

 

 —

 

 —

 

Expected volatility

 

71.00

%  

76.84

%