Loss Per Share (Tables)

6 Months Ended

Jun. 30, 2012

Dilutive Shares Which Could Exist Pursuant to Exercise of Outstanding Stock Instruments and Which Were Not Included in Calculation

Dilutive shares which could exist pursuant to the exercise of outstanding stock instruments and which were not included in the calculation because their affect would have been anti-dilutive are as follows:

	June 30, 2012 (shares)		June 30, 2011 (shares)
Warrants to purchase shares of common stock		7,424,241		7,131,567
Options to purchase shares of common stock		3,291,630		3,218,916
Restricted shares subject to vesting		–		20,834
Shares of common stock issuable upon conversion of preferred stock		2,627,110		2,635,444
		13,342,981		13,006,761