A STUDY OF THE SX PHE STAR BL CAM

We determined the physical parameters of the SX Phe star BL Cam from newly available times of maximum light and other times from the literature, as well as from uvby − β photoelectric photometry. From our analysis we found that this star is a binary system. The mass of the companion star was calculated in term of the mass of the primary star and the orbital angle. For this star we determined a metallicity [Fe/H] of −1.2 ± 0.3.

Reflective Quasi-Continuous Metasurface with Continuous Phase Control for Light Focusing

Benefitting from the arbitrary and flexible light modulation, metasurface has attracted extensive attention and been demonstrated in different applications. However, most reported metasurface-based devices were normally composed of discrete micro or nano structures, therefore the discretization precision limited the performance of the device, including the focusing efficiency, stray light suppression, and broadband performance. In this work, an all-metallic reflective metasurface consisting of numerous quasi-continuous nanostructures is proposed to realize high-efficiency and broadband focusing. The constructed quasi-continuous metasurface (QCMS) is then verified numerically through electromagnetic simulation, and the numerical results show a higher focusing efficiency and a better stray light suppression effect, compared to a binary-phase-based metalens. Through the same design strategy, a QCMS with the ability to overcome the diffraction limit can also be constructed, and a focal spot with the size of 0.8 times the diffraction limit can be achieved. We expect that this quasi-continuous structure could be utilized to construct other high-performance devices that require continuous phase controls, such as the beam deflector, orbital angle momentum generator, and self-accelerating beam generator.

Description of two new species of the genus Heterochelamon Türkay & Dai, 1997 (Crustacea: Decapoda: Brachyura: Potamidae), from southern China

This study describes two new species of freshwater crab of the genus Heterochelamon Türkay & Dai, 1997 from southern China, H. huidongense from Guangdong Province and H. jinxiuense from Guangxi Zhuang Autonomous Region. The two new species can be differentiated from congeners by characters derived from the shape of the epibranchial tooth, external orbital angle, cheliped proportions and structure of the male first gonopod. The present study brings the number of Heterochelamon species to seven. We used the mitochondrial 16S rRNA gene for a molecular analysis and the results are consistent with the morphological features that support the recognition of two new taxa.

Deep-sea spider crabs of the family Epialtidae MacLeay, 1838, from PapuaNew Guinea, with a redefinition of Tunepugettia Ng, Komai & Sato, 2017, and descriptions of two new genera (Crustacea: Decapoda: Brachyura: Majoidea)

The deep-water epialtid spider crab (superfamily Majoidea) material collected from recent French expeditions to Papua New Guinea (BIOPAPUA 2010, PAPUA NIUGINI 2012, MADEEP 2014, and KAVIENG 2014) was studied. In addition to several new records for the country, five new species of Oxypleurodon Miers, 1885, Rochinia A. Milne-Edwards, 1875, and Tunepugettia Ng, Komai & Sato, 2017, are described. The taxonomy of Tunepugettia is reappraised, and a new genus, Crocydocinus n. gen., is established, characterised by its smooth ambulatory legs and a distinct male first gonopod structure. Four species from the Bay of Bengal, Sumatra, and Réunion Island, currently placed in Rochinia and Tunepugettia are transferred to Crocydocinus n. gen. and four new species from Papua New Guinea, Philippines, and Vanuatu are described. A new genus, Neophrys n. gen., with one new species from Papua New Guinea, is established, and is characterised by the supraorbital eave being fused with the carapace and the poorly developed pre-orbital angle.

A new shrimp species of the genus Leptomenaeus Bruce, 2007 (Crustacea: Decapoda: Pontoniinae) from Vietnam

A new species of pontoniine shrimp, Leptomenaeus nhatrangensis sp. nov., is described and illustrated. This new species is the second representative of the genus. It is distinguishable from L. dolichosternum (Okuno and Mitsuhashi 2003) by the straight dorsal outline of the carapace and rostrum (1), by the rostrum overreaching the basal antennular peduncle (2), a subacute lower orbital angle (3), serrate cutting edges on the first pereiopod chela (4), fingers of the second pereiopod chela not markedly longer than palm (5), and the sixth abdominal segment not distinctly longer than postorbital carapace length (6). A single specimen of this new species was found in shallows of the Nhatrang Bay, southeastern Vietnam, on the lower surface of a large boulder.