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Redeemable Common Stock and Stock Purchase Warrants (Details) | 9 Months Ended | 12 Months Ended
--- | --- | ---
Jan. 31, 2014 | Apr. 30, 2013
Dividend yield | 0.00% | 0.00%
Minimum [Member] |  |
Expected term in years | 2 years 2 months 12 days | 2 years 10 months 24 days
Risk-free interest rates | 0.70% |
Volatility | 93.00% | 95.00%
Maximum [Member] |  |
Expected term in years | 3 years 10 months 24 days | 4 years 8 months 12 days
Risk-free interest rates | 1.50% | 0.30%
Volatility | 107.00% | 98.00%

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- Definition Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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- Definition Period the instrument, asset or liability is expected to be outstanding, 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/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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- Definition Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258 + Details
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