Although very minimalistic<p><a href="http:&#x2F;&#x2F;www-rohan.sdsu.edu&#x2F;~aty&#x2F;index.html" rel="nofollow">http:&#x2F;&#x2F;www-rohan.sdsu.edu&#x2F;~aty&#x2F;index.html</a><p>is the best presentation I know about the effect.