The trade-off between gain efficiency and noise figure is evaluated for an optimised EDFA pumped at 980nm. It is shown that operating at rrirxfmum gain efficiency elwavs results in an increased noise figure well above the 3dB quantum limit and that any attempt to reduce the amplifier noise figure results in a decrease in gain efficiency. Alternatively, for a fixed amplifier gain and pump power,...

Molecular motors transduce chemical energy obtained from hydrolizing ATP into mechanical work exerted against an external force. We calculate their efficiency at maximum power output for two simple generic models and show that the qualitative behaviour depends crucially on the position of the transition state or, equivalently, on the load distribution factor. Specifically, we find a transition ...

We investigate the efficiency of power generation by thermochemical engines. For strong coupling between the particle and heat flows and in the presence of a left-right symmetry in the system, we demonstrate that the efficiency at maximum power displays universality up to quadratic order in the deviation from equilibrium. A maser model is presented to illustrate our argument.

239 Elastomers and plastomers: their chemistry, physics, and technology. (Vol. III.) R. Houwink, Ed. Reviewed by H. Mark 239 Foundations of nuclear physics: faesimilies of thirteen original studies: Robert T. Beyer, Ed. Reviewed by Karl Lark-Hororitz 239 Advances in catalysis and related subjcets: XV. G. Frankenburg, V. I. Komaiclrewsly, and E. K. Rideal, Eds. Reviewed by Henry Eyring 2.40 Deta...

Plant biotypes that are resistant to S-triazines under most conditions often grow less vigorously and have lower quantum yields and lower maximum rates of photosynthesis. The photosynthetic reactions responsible for these effects were identified in whole leaves and thylakoids of nearly isonuclear lines of oilseed rape (Brassica napus L.). The lower quantum yield was a result of poor efficiency ...