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Stock Options, Stock Purchase Plan and Warrants (Details 3)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Valuation of option items under trinomial lattice model
Expected term in years	3 years 8 months 12 days	3 years 7 months 6 days
Risk-free interest rate (%)	0.60%	1.18%
Weighted average expected volatility (%)	51.00%	55.00%
Dividend yield (%)	0.00%	0.00%
Chief Medical Officer [Member]
Valuation of option items under trinomial lattice model
Expected term in years	3 years 9 months 18 days
Risk-free interest rate (%)	0.40%
Weighted average expected volatility (%)	53.00%
Dividend yield (%)	0.00%

The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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