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简述了水母的早期化石记录，并根据华南寒武系发现的立方水母干群化石，讨论了祖先型水母的辐射对称、躯体构型、生活史、生活习性，以及外骨骼的形成特征，推测水母类在寒武纪大爆发初期先于两侧对称动物基本完成其高级分类单元的宏演化。寒武纪的水母在生活习性上可以分为底栖固着型和游泳型两种。, We introduced the fossil records of medusa in brief and discussed the radial symmetry, body plan, life history, and exoskeleton of ancestral medusae. It is hypothesized that major clades of superclass medusa should have derived prior to that of ballerinas at the dawn of Cambrian explosion. The Cambrian medusae should be classified as sessile benthic and pelagic forms.

Based on the accurate definition of light intensity of nonparaxial scalar beams at the transverse plane,a comparative study of the beam widths,far-field divergence angles and M2 factors defined by the power in the bucket and second-order moment is made.Taking the nonparaxial diffraction of a small circular aperture as an example,the detailed numerical calculation is performed.The results show that the beam width,far-field divergence angle and M2 factor defined by the power in the bucket are less than that defined by the second-order moment.Both M2 factors tend to zero as beam waist vanishes,the propagation of beam width defined by the power in the bucket is different from the hyperbolic law.

The genus Sphenothallus was erected by Hall (1847, p. 261), who originally considered it a land plant. Sphenothallus was later classified as a marine invertebrate. Moore and Harrington (1956, p. F65) regarded Sphenothallus as a hydrozoan or scyphozoan. Van Iten et al. (1992, p. 139) supported Moore and Harrington's idea, and argued that it displays a close relationship to conularids (also see Li, 2000, p. 91). However, Mason and Yochelson (1985, p. 93–94) suggested that Sphenothallus is an annelid or “worm” (also see Fauchald et al., 1986, p. 64; Feldmann et al., 1986, p. 344–345; Choi, 1990, p. 403; Bartels et al., 1998, p. 114–117). The exact phylogenetic affinity of Sphenothallus is still debated.

The quasi-stationary profiles of the impurity ionization stages in HT-6B Tokamak were absolutely determined by monitoring the VUV and visible line emissions. An impurity transport code was set up. The impurity transport coefficients and other parameters about impurities were determined. From the changes of impurity emission profiles, it was concluded that the impurity confinement was improved and the impurity recycling was reduced by the slow magnetic compression along the minor radius. Some characteristics about the impurity transport in this small device are discussed.