Acknowledgement

This document was created with the financial support of the Secretary of education CR: MSM0021620838, LC536, 1ET100300517, 1ET101120503, 1ET201120505; the Grant agency of the Czech Republic: GA201/05/H014, GA405/05/0913 and the Grant agency of Charles University Prague: UK350/2005, UK352/2005, UK375/2005.