Evidence is presented to demonstrate that colour polymorphism in a beetle arises from structural colours produced by a five-layered reflector in the elytron. The colour of leaf beetles, Plateumaris sericea, ranges across the visible spectrum from blackish-blue to red. The elytra have two distinct layers: epicuticle and exocuticle. Morphological observations reveal that the multilayer structure within the exocuticle differs little among the different colour morphs but the layers within the epicuticle have characteristic thicknesses corresponding to the observed colour. The reflectors, consisting of five layers within the epicuticle, are responsible for all the different colours observed in P. sericea, as shown by theoretical analyses for a multilayer stack, and by showing that removal of the elytral surface, including epicuticle, results in the disappearance of the iridescent colour.

To investigate the mechanisms underlying pseudopod protrusion in locomoting neutrophils, we measured the intracellular stiffness and viscosity in the leading region, main body, and trailing region from displacements of oscillating intracellular granules driven with an optical trap. Experiments were done in control conditions and after treatment with cytochalasin D or nocodazole. We found 1) in the body and trailing region, the granules divided into a “fixed” population (too stiff to measure) and a “free” population (easily oscillated; fixed fraction 65%, free fraction 35%). By contrast, the fixed fraction in the leading region was <5%. 2) In the body and trailing region, there was no difference in stiffness or viscosity, but both were sharply lower in the leading region (respectively, 20-fold and 5-fold). 3) Neither cytochalasin D nor nocodazole caused a decrease in stiffness, but both treatments markedly reduced the fixed fraction in the body and trailing region to <20% and <40%, respectively. These observations suggest a discrete lattice structure in the body and trailing region and suggest that the developing pseudopod has a core that is more fluidlike, in the sense of a much lower viscosity and an almost total loss of stiffness. This is consistent with the contraction/solation hypothesis of pseudopodial formation.

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A new process capable of scattering intense anti-Stokes waves that uses stimulated electronic Raman scattering in metal vapor is proposed. The coherent material excitation produced by a prepump pulse couples with the forthcoming main pulse exclusively to create polarization that radiates the anti-Stokes wave. The selection rule governed by angular momentum conservation is the key to cause such strong coupling to induce unidirectional upconversion without any population inversion. The power conversion efficiency from the pump wave to the anti-Stokes wave is theoretically expected to reach 100% in this process.

Based on viewpoint that O2 is the most informative indication of gas degradation in transversely excited atmospheric (TEA) CO2 lasers, we have experimentally investigated the O2 concentration using a 100 Hz, 500 W class TEA-CO2 laser with a catalytic gas recycler. A simple theoretical model is also proposed to describe the O2 concentration and then compared with experimental data over a wide range of operating conditions. The results show that the model can be used for design of optimized gas recyclers.

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