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)
6 Months Ended
Jun. 30, 2018
USD ($)
$ / shares
shares
Outstanding at beginning of period (in shares) 3,687,679
Outstanding at beginning of period (in dollars per share) | $ / shares $ 1.50
Granted (in shares) 470,000
Granted, weighted average exercise price (in dollars per share) | $ / shares $ 0.53
Exercised (in shares)
Canceled and Forfeited (in shares) (5,000)
Canceled and Forfeited, weighted average exercise price (in dollars per share) | $ / shares $ 0.51
Expired (in shares) (7,000)
Expired (in dollars per share) | $ / shares $ 0.66
Outstanding at end of period (in shares) 4,145,679
Outstanding at end of period (in dollars per share) | $ / shares $ 1.39
Outstanding at end of period (Year) 6 years 219 days
Outstanding at end of period | $
Exercisable at end of period (in shares) 2,321,683
Exercisable at end of period (in dollars per share) | $ / shares $ 1.97
Exercisable at end of period (Year) 4 years 219 days
Exercisable at end of period | $