Note 4 - Common Stock (Details Textual) - shares	Dec. 31, 2021	Dec. 31, 2020
Common Stock, Shares, Issued, Total (in shares)	31,227,300	25,639,702
Common Stock, Shares, Outstanding, Ending Balance (in shares)	30,263,791	25,228,951
Reserved For Issuance Upon Exercise Or Vesting Of Equity Awards [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	5,600,676
Reserved For Issuance Upon Exercise Or Vesting Of Equity Awards [Member] \| Share-based Payment Arrangement, Option [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	434,500
NIL Coupon Non-redeemable Convertible Unsecured Loan Notes [Member] \| Unsecured Debt [Member]
Common Stock, Capital Shares Reserved for Future Issuance (in shares)	6,715

Aggregate number of common shares reserved for future issuance.

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