4. Stockholders' Equity (Tables)

6 Months Ended

Jun. 30, 2013

STOCKHOLDERS' DEFICIT

Assumptions Used in Black-Scholes Option-Pricing Model

		Six Months Ended June 30, 2013				Six Months Ended June 30, 2012
Expected Term		5 years				5 years
Volatility			118% - 131	%			98% - 115	%
Dividend yield			0.0	%			0.0	%
Risk-free interest rate			0.81% - 2.52	%			0.27% - 2.11	%

Summary of Option Activity under Plan and Related Information

		Six Months Ended June 30, 2013								Six Months Ended June 30, 2012
		Shares				Weighted Average Exercise Price				Shares				Weighted Average Exercise Price
Outstanding at beginning of period			2,135,630			$	1.26				1,236,342			$	2.47
Forfeited/cancelled			(356,000	)		$	1.61				(263,050	)		$	1.71
Granted			1,400,000			$	0.90				380,000			$	0.40
Outstanding at end of period			3,179,630			$	1.06				1,353,292			$	2.10
Expected to vest			1,394,613			$	0.78				286,400			$	2.10
Options exercisable			893,380			$	1.79				875,958			$	2.60
Weighted-average fair value of options granted during the period						$	0.77							$	0.32

Summary of warrants outstanding

		Number of Warrants				Exercise Price			Expiration Date
Issued to co-placement agents in connection with previous convertible note financings			18,250			$	7.84		10/29/2014
Issued in connection with 2009 private placement			503,034				3.4375		10/29/2014
Issued in connection with IPO			4,043,569				3.4375		3/24/2015
Issued to IPO underwriters that, if exercised, would result in the issuance of an additional 4,812 shares of common stock and warrants to purchase an additional 2,406 shares of common stock			4,812				3.90		3/24/2015
Issued in connection with September 20, 2012 private placement of convertible notes			2,125,000				0.40		9/20/2017
Issued to placement agent in connection with September 20, 2012 private placement of convertible notes			209,500				0.40		9/20/2017
Issued in connection with November 13, 2012 private placement of convertible notes			705,000				0.40		11/13/2017
Issued to placement agent in connection with November 13, 2012 private placement of convertible notes			118,500				0.40		11/13/2017
Issued in connection with February 2013 private placement			400,000				1.50		2/19/2018
Total warrants outstanding at June 30, 2013			8,127,665

Tabular disclosure of warrants or rights issued. Warrants and rights outstanding are derivative securities that give the holder the right to purchase securities (usually equity) from the issuer at a specific price within a certain time frame. Warrants are often included in a new debt issue to entice investors by a higher return potential. The main difference between warrants and call options is that warrants are issued and guaranteed by the company, whereas options are exchange instruments and are not issued by the company. Also, the lifetime of a warrant is often measured in years, while the lifetime of a typical option is measured in months. Disclose the title of issue of securities called for by warrants and rights outstanding, the aggregate amount of securities called for by warrants and rights outstanding, the date from which the warrants or rights are exercisable, and the price at which the warrant or right is exercisable.

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