A technique involves providing an actual cost commitment and investing a retail value of the actual cost commitment to a student venture, and receiving a return on the retail value and a return on actual cost that is equal to the return on the retail value minus the actual cost commitment. Mechanical changes or flow changes in a well can be caused by solid degradable polymer that changes physical properties after it is placed in a well. 1 to 10% by weight, and at least one silanol condensation catalyst, and is characterised in that the composition has a branching parameter value of at least 0. A device for measuring the inside diameter of a vessel according to the invention includes a tube, measuring wires, and a knob. Decoders 15i respectively decode the data stored in the separate buffers 14i. Other methods and apparatus are also provided.