Basis of Presentation and Significant Accounting Policies (Tables)

6 Months Ended

Jun. 30, 2013

Fair Value Measurement Specific to Assets or Liability

The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.


	Fair Value Measurements at Reporting Date Using
	Balances as of June 30, 2013		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Certificates of deposit	$	4,008,305	$	—	$	4,008,305	$	—

Short-term investments	$	6,482,467	$	6,482,467	$	—	$	—

Warrants liability	$	1,042,500	$	—	$	—	$	1,042,500


	Fair Value Measurements at Reporting Date Using
	Balances as of December 31, 2012		Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Certificates of deposit	$	6,502,825	$	—	$	6,502,825	$	—

Short-term investments	$	7,504,444	$	7,504,444	$	—	$	—

Warrants liability	$	498,587	$	—	$	—	$	498,587

Stock-Based Compensation Expense

For the three and six month periods ended June 30, 2013 and 2012, the Company recorded stock-based compensation expense as follows:


	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012
Research and development	$	21,612	$	18,303	$	40,375	$	36,605
General and administrative		23,276		26,787		46,265		53,575

Total stock-based compensation	$	44,888	$	45,090	$	86,640	$	90,180

Potential Shares Excluded from Determination of Basic and Diluted Net Loss Per Share

The potential shares, which are excluded from the determination of basic and diluted net loss per share as their effect is anti-dilutive, are as follows:


	June 30,
	2013		2012
Options to purchase common stock		3,511,202		3,479,108
Warrants to purchase common stock		8,710,870		7,523,370

Potential equivalent common stock excluded		12,222,072		11,002,478