DERIVATIVE INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2013

Derivative Instruments And Hedging Activities Disclosure [Abstract]

Fair Value of Warrants

The assumptions used principally in determining the fair value of warrants were as follows:

	June 30, 2013
Risk-free interest rate	0.30%-0.327%
Expected dividend yield	0%
Expected term	2.42-2.57 years
Expected volatility	97.1%

Changes in Derivative Warrant Liability

The table below presents the changes in derivative warrant liability for the six months ended June 30:

	Six Months Ended June 30,
	2013			2012
Balance at December 31,	$	14,584,818		$	35,473,230
Increase (decrease) in the fair value of the warrants		18,871,329			(10,567,444	)
Reduction in derivative liability due to exercise and modification of warrants		(33,456,147	)		(1,377,904	)
Balance at June 30,	$	—		$	23,527,882