Thanks a lot Danny. You and Ackbeet are always helping me undertand this vast subject of DE I am just scratching the surface of!
Is it the initial value theorom about the initial condition of ?
This to me would suggest, from having a read through some control engineering notes (that I have dusted down from my attic from many years ago!) that the behaviour of the system as the complex laplace variable, in our case, hits the limit of infinity the system output will tend to zero- this interprets as high frequency response in control systems.... is this what you were thinking ackbeet?