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Note 5 - Stockholders' Equity (Details) - Stock Options Valuation Assumptions
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9 Months Ended | |
|---|---|---|
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Jan. 31, 2014
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Jan. 31, 2013
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| Note 5 - Stockholders' Equity (Details) - Stock Options Valuation Assumptions [Line Items] | ||
| Risk-free interest rate | 2.97% | 2.97% |
| Expected life, in years | 6 years | 6 years |
| Dividend yield | 0.00% | 0.00% |
| Forfeiture rate | 11.40% | 9.20% |
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Minimum [Member]
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| Note 5 - Stockholders' Equity (Details) - Stock Options Valuation Assumptions [Line Items] | ||
| Expected volatility | 82.59% | 65.52% |
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Maximum [Member]
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| Note 5 - Stockholders' Equity (Details) - Stock Options Valuation Assumptions [Line Items] | ||
| Expected volatility | 83.23% | 80.48% |