Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Stock-based Compensation - Summary of Stock Option Activity (Details)

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Note 6 - Stock-based Compensation - Summary of Stock Option Activity (Details)
3 Months Ended
Mar. 31, 2018
USD ($)
$ / shares
shares
Outstanding at beginning of period (in shares) | shares 3,687,679
Outstanding at beginning of period (in dollars per share) | $ / shares $ 1.50
Granted (in shares) | shares 470,000
Granted, weighted average exercise price (in dollars per share) | $ / shares $ 0.53
Exercised (in shares) | shares
Exercised, weighted average exercise price (in dollars per share) | $ / shares
Canceled and Forfeited (in shares) | shares (5,000)
Canceled and Forfeited, weighted average exercise price (in dollars per share) | $ / shares $ 0.51
Expired (in shares) | shares
Expired (in dollars per share) | $ / shares
Outstanding at end of period (in shares) | shares 4,152,679
Outstanding at end of period (in dollars per share) | $ / shares $ 1.39
Outstanding at end of period (Year) 6 years 292 days
Outstanding at end of period | $
Exercisable at end of period (in shares) | shares 2,159,746
Exercisable at end of period (in dollars per share) | $ / shares $ 2.06
Exercisable at end of period (Year) 4 years 182 days
Exercisable at end of period | $