Quarterly report pursuant to Section 13 or 15(d)

Note 11 - Stockholders' Equity (Details Textual)

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Note 11 - Stockholders' Equity (Details Textual)
 3 Months Ended 6 Months Ended 12 Months Ended
May 01, 2024
USD ($)
$ / shares
shares
Jun. 30, 2024
USD ($)
shares
Mar. 31, 2024
USD ($)
shares
Jun. 30, 2024
USD ($)
shares
Jun. 30, 2023
USD ($)
Dec. 31, 2019
shares
Dec. 31, 2023
shares
Share-Based Payment Arrangement, Shares Withheld for Tax Withholding Obligation (in shares)       456,646      
Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation | $       $ 360,000      
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in shares)       68,882      
Proceeds from Issuance of Common Stock | $       $ 2,542,000 $ 2,784,000    
Proceeds from Issuance Or Sale Of Equity, Net | $       $ 7,306,000 $ 0    
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)   1,797,839   1,797,839     1,420,454
The 2014 Stock Incentive Plan [Member]              
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)     635,215        
The 2019 Stock Incentive Plan [Member]              
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant (in shares)   1,162,624   1,162,624      
Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized (in shares)           18,500,000  
The 2019 Stock Incentive Plan [Member] | Maximum [Member]              
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period (Year)           10 years  
May 2024 Public Offering Warrants [Member]              
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right (in shares) 1            
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares $ 0.01            
Warrants and Rights Outstanding | $ $ 3,100,000            
May 2024 Warrants [Member]              
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares $ 0.39            
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) 20,125,000            
Proceeds from Issuance of Warrants | $ $ 3,000,000            
Warrants and Rights Outstanding, Term (Year) 5 years            
May 2024 Warrants [Member] | Underwriter [Member]              
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares $ 0.4875            
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) 782,500            
Sale of Stock, Warrants, Commission Percent 2.00%            
Proceeds from Issuance of Warrants | $ $ 100,000            
Warrants and Rights Outstanding, Term (Year) 5 years            
ATM [Member]              
Stock Issued During Period, Shares, New Issues (in shares)       5,039,383      
Proceeds from Issuance of Common Stock | $       $ 2,500,000      
May 2024 Public Offering [Member]              
Stock Issued During Period, Shares, New Issues (in shares) 20,125,000            
Shares Issued, Price Per Share (in dollars per share) | $ / shares $ 0.39            
Proceeds from Issuance or Sale of Equity | $ $ 7,300,000            
Proceeds from Issuance Or Sale Of Equity, Net | $ $ 4,200,000            
Restricted Stock Units (RSUs) [Member]              
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period (in shares)   125,000 111,522        
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Fair Value | $   $ 40,000 $ 60,000        
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period, Number of Installments   3 3        
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)   3 years 3 years        
Management and Employees [Member]              
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)       1,064,286      
Management and Employees [Member] | Reissued Treasury Stock [Member]              
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)       428,566      
Board Members [Member]              
Stock Issued During Period, Shares, Restricted Stock Award, Gross (in shares)       79,547