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2. STOCK-BASED COMPENSATION (Details 1) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Aug. 31, 2012	Aug. 31, 2011
Stock-Based Compensation Details 1
Expected term (in years)	5 years	5 years
Volatility	90.00%	80.00%
Expected dividend	$ 0	$ 0
Risk-free Interest Rates	0.75%	1.57%
Estimated Forfeiture Rate	0.25%	0.25%
Weighted Average Grant Date Fair Value	$ 0.88	$ 0.80

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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