A method for evaluating statistical congruence of an existing or putative portfolio with a target portfolio, both the current portfolio and the target portfolio having a plurality of assets. The compounds are sphingosine analogs that, after phosphorylation, can behave as agonists at S1P receptors. The ecological restoration block of this invention can effectively preserve wild animals and plants by providing protective habitat at the front part of the body and by allowing the animals to move freely through the first and fourth migration channels. The drill bit is effective to provide stabilised cutting to minimise lateral deflection. The quantum well layer has a thickness 4 times or less the unit lattice thickness of SrTiO3 which has been converted into a semiconductor by doping an n-type impurity therein.