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Warrant Liability (Tables)

6 Months Ended

Jun. 30, 2012

Warrant Liability [Abstract]

Assumptions for Black-Scholes option pricing model


		To Calculate Fair Value of Warrant Liability at
		June 30, 2012				December 31, 2011
Expected life (years)			1.9				2.4
Risk-free interest rate			0.3	%			0.3	%
Expected volatility			81.0	%			74.1	%
Expected dividend yield			0	%			0	%


		At June 30, 2012				At December 31, 2011				Change in Fair Value of Warrant Liability
Fair value of liability for warrants issued in 2008		$	1,552			$	2,224			$	(672	)


		To Calculate Fair Value of Warrant Liability at
		June 30, 2012				December 31, 2011
Expected life (years)			2.8				3.3
Risk-free interest rate			0.4	%			0.5	%
Expected volatility			73.5	%			90.8	%
Expected dividend yield			0	%			0	%


		At June 30, 2012				At December 31, 2011				Change in Fair Value of Warrant Liability
Fair value of liability for warrants issued in 2009		$	4,600			$	28,971			$	(24,371	)

Assumptions used for simulation model


Risk-free interest rate per year			0.6	%
Expected volatility per year			86.6	%
Expected dividend yield			0	%
Expected life in years			4.5

Summary of changes in fair value of warrant liability


		Series A								Series B
		Number of Warrants				Fair value $				Number of Warrants				Fair value $
Balance at March 31, 2012			8,900,000			$	6,234,984				7,100,000			$	4,769,140
Add Issued			1,800,000				1,106,618				—				—
Less exercised			—				—				(1,800,000	)			(527,799	)
Less expired			—				—				(5,300,000	)			(3,560,063	)
Changes in fair value			—				(1,951,584	)			—				(681,278	)

Balance at June 30, 2012			10,700,000			$	5,390,018				—			$	—

Summary of outstanding warrants and fair value of warrant liability


Warrants		Number Outstanding				Exercise Price $				Fair value $
Warrants issued in 2008			1,034,483				23.00				1,552
Warrants issued in 2009			400,000				15.00				4,600
Series A Warrants			10,700,000				1.40				5,390,018

Total			12,134,483								5,396,170