From 2007.igem.org

Supposing that the degradation rate of AHL increases to three times faster than the original one, we simulate the changing tendency of contents of various parameters on our computer. The output signal would only appear when the input signal switches from 0 to 1. The reason is that with the addition of IPTG, AHL are produced very quickly which bind to undegraded LuxR protein to initialize the production of GFP. But with the ceasing of IPTG, AHL are decomposed in a very short time leaving little AHL to bind LuxR protein and only a low peak of GFP could be observed as the left graph displays.