Note 11 - Stockholders' equity (Detail) - Fair value estimated by Black-Scholes option-pricing model	12 Months Ended
Dec. 31, 2011
December 31, 2011	1.95%
December 31, 2011	5 years
December 31, 2011	63.01%
December 31, 2011

- Definition

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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