Edge State, Band Topology, and Time Boundary Effect in the Fine-Grained Categorization of Chern Insulators.

We predict novel topological phases with broken time-reversal symmetry supporting the coexistence of opposite chiral edge states, which are fundamentally different from the photonic spin-Hall, valley-Hall, and higher-order topological phases. We find a fine-grained categorization of Chern insulators, their band topologies characterized by identical Chern numbers are completely different. Furthermore, we prove that different topologies cause zeros in their Bloch wave function overlaps, which imprint the band gap closing and appear at the degenerate points of topological phase transition. The Bloch wave function overlaps predict the reflection and refraction at a topological time boundary, and the overlap zeros ensure the existence of vanishing revival amplitude at critical times even though different topologies before and after the time boundary have identical Chern numbers. Our findings create new opportunities for topological metamaterials, uncover the topological feature hidden in the time boundary effect as a probe of topology, and open a venue for the exploration of the rich physics originating from the long-range couplings.

Vertical microbiological variation of a coastal aquifer in southern China.

Microbial communities in a coastal aquifer in the Zhuhai region of southern China were investigated by culture-independent molecular approaches. Four 16S rRNA gene libraries of three groundwater samples from varied depths and one seawater sample were constructed and analysed by the amplified ribosomal DNA restriction analysis technique (ARDRA). The phylogenetic analysis indicated that the 16S rDNA of clones presenting dominant ARDRA patterns were most similar to Proteobacteria, Bacteroidetes, Actinobacteria, Planctomycetes, and candidate divisions OPx (such as OP3, OP8, and OP11). In samples extracted from wells of 5-, 20-, and 35-m depth (i.e., D1, D5, and D6) Proteobacteria made up 32.3, 34.3, and 46.7% of the microbial communities, respectively. The same samples from D1, D5, and D6 also consisted of 5.0, 11.2, and 6.5% Bacteroidetes and 5.4, 6.6, and 7.8% Actinobacteria, respectively. In contrast, the seawater clone library had a predominant number of Proteobacteria (32.8%), while Bacteroidetes and Planctomycetes both accounted for 9.3%. Total microbial diversity remained relatively constant over the top layer to a depth of approximately 35 m, significant community vertical and horizontal (seawater-groundwater) shifts were observed for certain bacterial populations.

[A study of the mechanism of production of night myopia at low luminance environment].

The mechanism of production of night myopia was investigated in detail by using a laser-speckle refractometer. Night myopia begins to appear at the luminance level with the emergence of rod (scotopic) vision and increases to a maximum average of 1.35 D with further decrease of environmental luminance for the completion of rod vision. It is demonstrated experimentally that both spherical and chromatic aberrations of the eye do not play an important role in the production of night myopia. It is therefore concluded that night myopia is posed on the dark focus of accommodation of the resting state focus of the eye in the absence of adequate stimulus during scotopic vision.

[Scanning electron microscopic observations on the copulatory spicules of the male Necator americanus and Ancylostoma duodenale].

Scanning electron microscopic observations were made on the morphological structures of the two copulatory spicules of the male Necator americanus and Ancylostoma duodenale. In both species, one of the two copulatory spicules was in the shape of a concave groove and the other, in the shape of an oblate tube. Owing to the difference in the concavity of the groove shaped copulatory spicule between the two species as shown by the cross sections, Necator americanus usually appear to have only one copulatory spicule whereas Ancylostoma duodenale usually show two separate copulatory spicules in appearance (Figs 1-10).