Note 6 - Fair Value of Measurements (Details) - Assets and Liabilities at Fair Value on a Recurring Basis (USD $)	Sep. 30, 2013	Dec. 31, 2012
Liabilities:
Common stock warrant liability	$ 5,252,660	$ 4,283,932
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Assets:
Short-term investments available for sale Bonds – corporate issuances	32,038,638	8,037,620
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 2 [Member]
Assets:
Short-term investments available for sale Bonds – corporate issuances	0	0
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 3 [Member]
Assets:
Short-term investments available for sale Bonds – corporate issuances	0	0
Corporate Debt Securities [Member]
Assets:
Short-term investments available for sale Bonds – corporate issuances	32,038,638	8,037,620
Fair Value, Inputs, Level 1 [Member]
Liabilities:
Common stock warrant liability	0	0
Fair Value, Inputs, Level 2 [Member]
Liabilities:
Common stock warrant liability	0	0
Fair Value, Inputs, Level 3 [Member]
Liabilities:
Common stock warrant liability	$ 5,252,660	$ 4,283,932