Human-competitive results produced by genetic programming

Genetic programming has now been used to produce at least 76 instances of results that are competitive with human-produced results. These human-competitive results come from a wide variety of fields, including quantum computing circuits, analog electrical circuits, antennas, mechanical systems, controllers, game playing, finite algebras, photonic systems, image recognition, optical lens systems, mathematical algorithms, cellular automata rules, bioinformatics, sorting networks, robotics, assembly code generation, software repair, scheduling, communication protocols, symbolic regression, reverse engineering, and empirical model discovery. This paper observes that, despite considerable variation in the techniques employed by the various researchers and research groups that produced these human-competitive results, many of the results share several common features. Many of the results were achieved by using a developmental process and by using native representations regularly used by engineers in the fields involved. The best individual in the initial generation of the run of genetic programming often contains only a small number of operative parts. Most of the results that duplicated the functionality of previously issued patents were novel solutions, not infringing solutions. In addition, the production of human-competitive results, as well as the increased intricacy of the results, are broadly correlated to increased availability of computing power tracked by Moore’s law. The paper ends by predicting that the increased availability of computing power (through both parallel computing and Moore’s law) should result in the production, in the future, of an increasing flow of human-competitive results, as well as more intricate and impressive results.     

Correlation of the dynamics of native human acetylcholinesterase and its inhibited huperzine A counterpart from sub-picoseconds to nanoseconds

It is a long debated question whether catalytic activities of enzymes, which lie on the millisecond timescale, are possibly already reflected in variations in atomic thermal fluctuations on the pico- to nanosecond timescale. To shed light on this puzzle, the enzyme human acetylcholinesterase in its wild-type form and complexed with the inhibitor huperzine A were investigated by various neutron scattering techniques and molecular dynamics simulations. Previous results on elastic neutron scattering at various timescales and simulations suggest that dynamical processes are not affected on average by the presence of the ligand within the considered time ranges between 10 ps and 1 ns. In the work presented here, the focus was laid on quasi-elastic (QENS) and inelastic neutron scattering (INS). These techniques give access to different kinds of individual diffusive motions and to the density of states of collective motions at the sub-picoseconds timescale. Hence, they permit going beyond the first approach of looking at mean square displacements. For both samples, the autocorrelation function was well described by a stretched-exponential function indicating a linkage between the timescales of fast and slow functional relaxation dynamics. The findings of the QENS and INS investigation are discussed in relation to the results of our earlier elastic incoherent neutron scattering and molecular dynamics simulations.     

High-speed performance of OMCVD grown InAlAs/InGaAs MSMphotodetectors at 1.5 μm and 1.3 μm wavelengths

A report is presented on the fabrication of high-speed In_0.53 Ga_0.47As metal-semiconductor-metal (MSM) photodetectors incorporating a high-quality lattice-matched InAlAs barrier enhancement layer, grown by organometallic chemical vapor deposition (OMCVD). Fast responses of ~55 ps full-width half-maximum at 1.5 μm and ~48 ps at 1.3 μm wavelengths are observed, corresponding to intrinsic device bandwidths of ~8 GHz and ~11 GHz, respectively. The absence of any tail to the pulse response, and of any low-bias DC gain, indicates a low-trap density at the InAlAs/InGaAs heterointerface. Bias independent dark currents of 10-20 μA are observed below breakdown, which occurred at >30 V in devices with a 500-A-thick InAlAs layer     

Controlled conversion of polyacrylamide into polyacrylic acid

Interaction of nitrous acid with aqua solution of poly(acrylamide) gives poly(acrylic acid) in quantitative conversion yields. The reaction proceeds smoothly, with simultaneous evolution of nitrogen, provided that the temperature below 5 °C. The procedure presented provides a versatile route to prepare acrylic acid-acrylamide copolymers in any desired composition, by adjusting molar ratio of nitrous acid. Received: 29 January 1997/Revised: 24 July 1997/Accepted: 6 August 1997     

Integration of GaAS MESFET drivers with GaAs directional-coupler electro-optic modulators

We demonstrate the first integration of active electronic devices with semiconductor waveguide modulators. By combining ion-implanted GaAs MESFET amplifiers with directional-coupler electro-optic modulators, the DC drive voltage has been reduced by a factor of ?v = 9, making an effective electro-optic figure-of-merit ?vn3r41 for GaAs superior to that of LiNbO3     

Integration of high-speed optical taps with InP waveguides

Optical taps are key elements for optical signal processing. The authors demonstrate the high-speed operation of an InGaAs p-i-n photodetector on InP waveguides. For a 300- mu m-long tap that samples 19% of the light propagating in a 7- mu m-wide waveguide, the response time is 50 ps at a 1 V reverse bias. The taps require a simple epitaxial growth and can readily be integrated with electrooptic modulators and other optoelectronic devices for multigigahertz optical signal processing.<>     

1.5 mu m compressive-strained multiquantum-well 20-wavelength distributed-feedback laser arrays

The wide gain spectrum of compressive-strained multiquantum-well active layers was used to fabricate 20-wavelength distributed-feedback laser arrays. A record wide-wavelength span of 131 nm in the 1.5 mu m wavelength region was demonstrated. The maximum intrinsic modulation response, measured by a parasitic-free optical modulation technique, reaches 16 GHz.<>