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Note 9 - Share-based Compensation - Fair Value Assumptions (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Share-Based Payment Arrangement, Option [Member] |  |  |
Expected volatility | 105.00% |  |
Expected dividend yield | 0.00% | 0.00% | 0.00%
Contractual life (years) (Year) | 10 years |  | 10 years
Share-Based Payment Arrangement, Option [Member] | SEED 2022 Share Incentive Plan [Member] |  |  |
Expected dividend yield | 0.00% | 0.00% |
Contractual life (years) (Year) | 10 years | 10 years |
Share-Based Payment Arrangement, Option [Member] | Minimum [Member] |  |  |
Fair value of ordinary share (in dollars per share) | $ 0.77 | $ 1.14 | $ 9.48
Risk-free interest rate | 3.47% | 1.23% | 0.37%
Expected term (years) (Year) | 5 years 25 days | 3 years 18 days | 5 years
Expected volatility |  | 100.00% | 75.00%
Contractual life (years) (Year) |  | 5 years |
Share-Based Payment Arrangement, Option [Member] | Minimum [Member] | SEED 2022 Share Incentive Plan [Member] |  |  |
Fair value of ordinary share (in dollars per share) | $ 0.19 | $ 0.44 |
Risk-free interest rate | 3.47% | 2.54% |
Expected term (years) (Year) | 5 years 14 days | 5 years 3 months |
Expected volatility | 105.97% | 99.34% |
Share-Based Payment Arrangement, Option [Member] | Maximum [Member] |  |  |
Fair value of ordinary share (in dollars per share) | $ 1.75 | $ 3.48 | $ 31.31
Risk-free interest rate | 4.29% | 3.16% | 1.47%
Expected term (years) (Year) | 6 years | 6 years | 7 years 5 months 26 days
Expected volatility |  | 115.00% | 90.00%
Contractual life (years) (Year) |  | 10 years |
Share-Based Payment Arrangement, Option [Member] | Maximum [Member] | SEED 2022 Share Incentive Plan [Member] |  |  |
Fair value of ordinary share (in dollars per share) | $ 0.44 | $ 0.5 |
Risk-free interest rate | 4.73% | 3.75% |
Expected term (years) (Year) | 6 years 6 months | 6 years 6 months |
Expected volatility | 141.40% | 106.73% |
Options Granted in May 2021 [Member] |  |  |
Fair value of ordinary share (in dollars per share) | $ 10.71 |  |
Risk-free interest rate | 1.63% |  |
Expected term (years) (Year) | 10 years |  |
Expected volatility | 75.00% |  |
Expected dividend yield | 0.00% |  |
Exercise price (in dollars per share) | $ 10.18 |  |

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- Definition Agreed-upon price for the exchange of the underlying asset relating to the share-based payment award. + References No definition available. + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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- Definition Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480429/718-10-50-2 + Details
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