GROWTH CIRCLE PATTERNS IN THE OTOLITH OF THE GRAY FISH (Osteochilus melanopleurus) FROM THE SIAK AND KAMPAR RIVERS

Osteochilus melanopleurus can be found in the Siak and Kampar Rivers. The Kampar Rivers waters are better than that of the Siak River and it affects the growth of the fish. The growth pattern is reflected in the pattern of otolith growth rings. The research aims to understand the pattern of otolith growth rings of the O. melanopleurus from both rivers has been conducted from January to February 2021. There were 55 fishes captured (28 males and 27 females). The otolith was taken using tweezers and shaved manually using a soft grindstone. The dark growth ring pattern was investigated using a binocular microscope. Results showed the size of fish captured was 220 to 360 mm from Siak River and 310 to 370 mm from Kampar River. In the fish with the same standard length, the size of the otolith from the Siak River is heavier and longer than that of the Kampar River, which means that fish growth from the Kampar River is better than that of the Siak River. The length of an otolith from Siak River ranged from 1.875 – 3.275 mm, the width was ranged from 1.575–2.75 mm and the weight of otolith was 0.0039 – 0.0098 g, while the length of an otolith from Kampar River ranged from 2.375–3.275 mm, the width was ranged from 1.85–2.575 mm and the weight of otolith was 0.0042 –0.0076 g. The maximum number of the dark ring in the otolith from the Siak River was 4 and Kampar River was 2. The distance between the nucleus and the first dark ring of fish from both rivers was varied from 0.1–0.525 mm, and there was no special pattern. This fact indicates that the first dark ring was formed individually and they were not formed by a periodical incidents during the fish life

TW Hya: an old protoplanetary disc revived by its planet

Dark rings with bright rims are the indirect signposts of planets embedded in protoplanetary discs. In a recent first, an azimuthally elongated AU-scale blob, possibly a planet, was resolved with ALMA in TW Hya. The blob is at the edge of a cliff-like rollover in the dust disc rather than inside a dark ring. Here we build time-dependent models of TW Hya disc. We find that the classical paradigm cannot account for the morphology of the disc and the blob. We propose that ALMA-discovered blob hides a Neptune mass planet losing gas and dust. We show that radial drift of mm-sized dust particles naturally explains why the blob is located on the edge of the dust disc. Dust particles leaving the planet perform a characteristic U-turn relative to it, producing an azimuthally elongated blob-like emission feature. This scenario also explains why a 10 Myr old disc is so bright in dust continuum. Two scenarios for the dust-losing planet are presented. In the first, a dusty pre-runaway gas envelope of a ∼40 M⊕ Core Accretion planet is disrupted, e.g., as a result of a catastrophic encounter. In the second, a massive dusty pre-collapse gas giant planet formed by Gravitational Instability is disrupted by the energy released in its massive core. Future modelling may discriminate between these scenarios and allow us to study planet formation in an entirely new way – by analysing the flows of dust and gas recently belonging to planets, informing us about the structure of pre-disruption planetary envelopes.

Optical coherence tomography angiography and choroidal neovascularization in multifocal choroiditis: A descriptive study

Purpose: To analyze the ability of optical coherence tomography angiography to identify choroidal neovascularization in multifocal choroiditis and to describe active and inactive choroidal neovascularization findings. Methods: Retrospective study of consecutive patients with multifocal choroiditis and choroidal neovascularization examined between January and November 2016. In addition to usual exams, optical coherence tomography angiography (AngioPlex™ CIRRUS™ HD-OCT model 5000; Carl Zeiss Meditec, Inc., Dublin, CA, USA) images were assessed for morphological analysis: choroidal neovascularization size, choroidal neovascularization margin (well or poorly circumscribed), choroidal neovascularization shape (tangled or interlacing), choroidal neovascularization core (feeder vessel) and dark ring around the choroidal neovascularization. Results: A total of 10 eyes were included. Optical coherence tomography angiography identified all choroidal neovascularization. Active choroidal neovascularization had well-circumscribed margins (67%), interlacing shape (83%), and a surrounding dark ring (83%). Inactive choroidal neovascularization had rather poorly circumscribed margins (75%), tangled shape, and “dead tree” appearance (50%) with less frequently a surrounding dark ring (50%). Conclusion: Optical coherence tomography angiography is adapted to confirm the diagnosis of choroidal neovascularization complicating multifocal choroiditis, but it is still insufficient to differentiate active and inactive lesions.

New description of Echiniscus scabrospinosus Fontoura, 1982, and description of a new species of Echiniscus (Heterotardigrada) from China

A redescription of Echiniscus scabrospinosus Fontoura, 1982, is presented. A comparison with the more similar species is made, based on information available since the original description. A previously unreported cuticular feature (a central dark ring in the light spots) is described for Echiniscus marginatus Binda & Pilato, 1994. A new species, Echiniscus lineatus sp. nov., is described from China. This new species has a double plate ornamentation with numerous dark polygons and fewer light spots, forming transverse stripes on the plates. Longitudinal stripes are also present on the scapular plate. The new species has lateral filaments A and spines B, C, D, and E, as well as dorsal spines C d and D d .