Reference
GoodPic.com - Lightbox.js で学ぶ script.aculo.us アニメーションの使い方http://www.goodpic.com/mt/archives2/2006/11/lightboxjs_scri.html
Effect.Transitions.sinoidal = function(pos) {
return (-Math.cos(pos * Math.PI) / 2) + 0.5;
}
new Effect.Move( 'elementId', {
x: 100,
y: 100,
transition : function ( pos ) {
return Math.pow( pos, 2 );
}
});