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v2.4.1.9

Redeemable Common Stock and Stock Purchase Warrants (Details) | 9 Months Ended | 12 Months Ended
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Jan. 31, 2015 | Apr. 30, 2014 | Apr. 30, 2013
Risk-free interest rates |  |  | 0.30%us-gaap_FairValueAssumptionsRiskFreeInterestRate
Dividend yield | 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate | 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate | 0.00%us-gaap_FairValueAssumptionsExpectedDividendRate
Minimum [Member] |  |  |
Expected term in years | 1 year 2 months 12 days | 1 year 10 months 24 days | 2 years 10 months 24 days
Risk-free interest rates | 0.60%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_RangeAxis = us-gaap_MinimumMember | 0.40%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_RangeAxis = us-gaap_MinimumMember |
Volatility | 73.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = us-gaap_MinimumMember | 95.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = us-gaap_MinimumMember | 95.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = us-gaap_MinimumMember
Maximum [Member] |  |  |
Expected term in years | 3 years | 3 years 8 months 12 days | 4 years 8 months 12 days
Risk-free interest rates | 1.05%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_RangeAxis = us-gaap_MaximumMember | 1.17%us-gaap_FairValueAssumptionsRiskFreeInterestRate / us-gaap_RangeAxis = us-gaap_MaximumMember |
Volatility | 100.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = us-gaap_MaximumMember | 113.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = us-gaap_MaximumMember | 98.00%us-gaap_FairValueAssumptionsExpectedVolatilityRate / us-gaap_RangeAxis = us-gaap_MaximumMember

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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=36462937&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=36462937&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=36462937&loc=d3e19207-110258 + Details
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- Definition Risk-free interest rate assumption used in valuing an instrument. + 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=36462937&loc=d3e19207-110258 + Details
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