Stock Purchase Warrants (Tables)

9 Months Ended

Sep. 30, 2013

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Schedule of Key Assumptions Utilized in Fair Value Calculation

Key assumptions utilized in the fair value calculation as of September 30, 2013 and December 31, 2012 appear in the table below.

	SEPTEMBER 30, 2013	DECEMBER 31, 2012
Expected term (years)	5.39–6.91	6.13–7.66
Volatility	65.00%	60.00%
Risk-free interest rate	1.51%–2.00%	0.98%–1.31%
Dividend yield