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Note 10 - Income Tax (Details) - Benefit (Provision) for Income Taxes Applying the Statutory Federal Income Tax
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12 Months Ended | ||
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Benefit (Provision) for Income Taxes Applying the Statutory Federal Income Tax [Abstract] | |||
| Tax benefit at statutory rate | 35.00% | 35.00% | 35.00% |
| Change in fair value of warrant liability | 0.60% | 2.10% | 261.50% |
| Stock based compensation | (2.10%) | (0.10%) | (1.90%) |
| Other | 0.50% | 0.00% | (1.90%) |
| Change in valuation allowance | (30.10%) | (37.00%) | (292.70%) |
| Expiration of loss carryforwards and credits | (2.90%) | 0.00% | 0.00% |
| Income tax benefit (provision) | 0.00% | 0.00% | 0.00% |