Case report: what gives the myopic tilted disc an oval appearance?

Background Myopic tilted disc, observed as an oval disc, has been alleged to be a funduscopic en-face manifestation of excessive optic nerve head (ONH) sloping or tilting. Here, we report the case of a myopic child showing a developing oval disc in fundus photos during axial elongation, but without progressive tilting in spectral-domain optical coherence tomography (SD-OCT) images. Case presentation By merging B-scan SD-OCT images of the ONH and macula, the curvature of the posterior pole, including both the fovea and ONH, was reconstructed and compared before and after 2 years of axial elongation. Despite the marked increase of disc ovality, the posterior polar curvature was rarely changed. The preponderance of optic disc change was induced by the shift of the temporal disc margin in the nasal direction. This shifting alone imitated an increase of tilt angle but one that was still far smaller than the required degree of tilt for ONH-tilt-based disc ovality. To clarify, we calculated the required extent of axial elongation to obtain a substantial degree of ONH tilt when considering the adjacency of the fovea and the ONH. Without a focal increase of posterior polar curvature, which is to say posterior staphyloma, such change is not possible until the axial length increases extraordinarily. Conclusion The most prominent change in the development of myopic tilted disc, which change gives it an oval appearance and imitates a tilt when measured, is actually not a tilt but rather a shift of the temporal disc margin.This work was supported by a clinical research grant-in-aid from the Seoul Medical Center (grant no. 03–2019-3). The funders had no role in study design, data collection and analysis, interpretation of data, decision to publish, or preparation of the manuscript

Anderson transition of in-gap quasiparticles in a quasi-two-dimensional disordered superconductor

The Anderson transition of Bogoliubov-de Gennes (BdG) quasiparticles in superconducting state has been studied theoretically for last three decades. However, its experimental proof is lacking. In particular, the relationship of the superconducting order-parameter fluctuations and the Anderson transition of BdG quasiparticles have not been well understood. Our study, based on scanning tunneling microscopy measurements, investigates how BdG quasiparticles become Anderson-localized and delocalized as a function of energy and applied magnetic field in a quasi-two-dimensional Fe-based superconductor with sufficient zero-bias BdG quasiparticles. The anomalous multifractal spectra based on the spatial distributions of the pairing gaps and the coherent peak heights suggest that superconducting fluctuations play a key role in the delocalization of in-gap BdG quasiparticles. Our real-space Hartree-Fock-BCS-Anderson simulations and renormalization group analysis with pairing fluctuations support quasiparticle localization and suggest that enhanced pairing fluctuations lead to delocalization of BdG quasiparticles and "weak localization" of phase-fluctuating Cooper pairs in quasi-two-dimensional disordered superconductors. The present study proposes that the 10-fold way classification scheme has to be generalized to take order-parameter fluctuations in actual quantum matter. Also, it shed light on how ac energy loss due to quasiparticles at Fermi level can be controlled in a quasi-2d superconductor with sufficient pairing fluctuation

Growth Kinetics and Optical Properties of CsPbBr3 Perovskite Nanocrystals

We synthesized CsPbBr3 perovskite nanocrystals (NCs) at different reaction temperatures and tracked their growth kinetics on the basis of their optical properties and estimated size. The energies of the absorption and fluorescence (FL) peaks with increasing reaction temperature for the CsPbBr3 perovskite NCs were tuned within the regions of 2.429-2.570 eV and 2.391-2.469 eV, respectively, depending on size of the NCs (9.9-12.5 nm). The Stokes shifts of CsPbBr3 perovskite NCs with increasing NC size decreased from 101 meV to 38 meV. The full-width at half-maximum of the FL peaks for the CdSe NCs decreased from 150 meV to 90 meV because of the improved size uniformity of the CsPbBr3 perovskite NCs. The energy spacing of CsPbBr3 perovskite NCs synthesized at various reaction temperatures was calculated from Tauc plots; this information is critical for determining the bandgap energy and enables the size of the CsPbBr3 perovskite NCs to be estimated using the effective mass approximation