Improved techniques for performing assays using nematode worms, such as nematode worms from the genus Caenorhabditis. A behavior verifier is coupled to the conversational system for extracting features from the inputs. This reduces the nonlinear amplification error due to temperature differences of transistors, thus achieving flat gain characteristics in broad ranges of frequencies. The first semantically meaningful elements are compared with the second semantically meaningful elements to identify predefined functions that correspond to action andor statement of the input statement. Because the fit of the sealing surfaces of the valve is less than perfect, and because the voids on mating surfaces do not necessarily overlap, the 5% of the surface area comprising interconnected voids can easily translate to a 10% or more reduction in sealed area when both sealing surfaces have the interconnecting voids.