Fair Value Measurement

6 Months Ended

Jun. 30, 2011

Fair Value Measurement [Abstract]

Fair Value Measurement

Note 3. Fair Value Measurement

     The following tables present our assets and liabilities that are measured at fair value on a recurring basis and are categorized using the fair value hierarchy. The fair value hierarchy has three levels based on the reliability of the inputs used to determine fair value.

Level 1 — Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 — Directly or indirectly observable inputs other than in Level 1, that include quoted prices for similar assets or liabilities in active markets or quoted prices for identical or similar assets or liabilities in markets that are not active.

Level 3 — Unobservable inputs which are supported by little or no market activity that reflects the reporting entity’s own assumptions about the assumptions that market participants would use in pricing the asset or liability.

     The fair value hierarchy also requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value.

     Our cash equivalents, marketable securities, bonds payable and warrant liability are classified within Level 1 or Level 2. This is because our cash equivalents and marketable securities are valued primarily using quoted market prices, our bonds payable are valued using alternative pricing sources and models utilizing market observable inputs and our warrant liability is valued using an option pricing model that uses assumptions with observable inputs such as risk-free interest rates that are derived from the yield on U.S. Treasury debt securities, volatility and price based on our common stock as traded on NASDAQ.

     We currently do not have any Level 3 financial assets or liabilities.

     The following table presents financial assets and liabilities measured at fair value:

	Fair Value Measurement
	at Reporting Date Using
	Quoted Prices		Significant
	in Active Markets		Other
	For		Observable		As of
	Identical Assets		Inputs		June 30,
	(Level 1)		(Level 2)		2011
Financial assets
Cash equivalents:
Money market funds	$	5,687,249	$	—	$	5,687,249
Marketable securities:
Debt securities		9,123,188		—		9,123,188
Total financial assets	$	14,810,437	$	—	$	14,810,437
Financial liabilities
Bond payable	$	—	$	613,750	$	613,750
Warrant liability		—		1,868,745		1,868,745
Total financial liabilities	$	—	$	2,482,495	$	2,482,495