Habitat fragmentation influences gene structure and gene differentiation among the Loxoblemmus aomoriensis populations in the Thousand Island Lake.

Thousand Island Lake (TIL) is a fragmented landscape consisting of more than 1000 land-bridge islands isolated during reservoir formation. To evaluate the effects of fragmentation and island attributes on insect populations, we examined the genetic structure of Loxoblemmus aomoriensis, a species of cricket widely distributed in TIL, and compared genetic diversity between islands samples. Population genetic analyses was conducted based on mitochondrial DNA haplotype frequencies of 10 sample islands. By comparing three island attributes with population genetic diversity reveals that island area influenced population genetic diversity (r2 = 0.5094, p = 0.00204). Using Pairwise Fst values, we also found that long-distance isolation increased the genetic differentiation, while short-distance isolation can be offset by dispersal. These results indicate that fragmentation can impact populations on a genetic level.

Convolution Operations on Coding Metasurface to Reach Flexible and Continuous Controls of Terahertz Beams.

The concept of coding metasurface makes a link between physically metamaterial particles and digital codes, and hence it is possible to perform digital signal processing on the coding metasurface to realize unusual physical phenomena. Here, this study presents to perform Fourier operations on coding metasurfaces and proposes a principle called as scattering-pattern shift using the convolution theorem, which allows steering of the scattering pattern to an arbitrarily predesigned direction. Owing to the constant reflection amplitude of coding particles, the required coding pattern can be simply achieved by the modulus of two coding matrices. This study demonstrates that the scattering patterns that are directly calculated from the coding pattern using the Fourier transform have excellent agreements to the numerical simulations based on realistic coding structures, providing an efficient method in optimizing coding patterns to achieve predesigned scattering beams. The most important advantage of this approach over the previous schemes in producing anomalous single-beam scattering is its flexible and continuous controls to arbitrary directions. This work opens a new route to study metamaterial from a fully digital perspective, predicting the possibility of combining conventional theorems in digital signal processing with the coding metasurface to realize more powerful manipulations of electromagnetic waves.