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National Research Foundation (NRF) Singapore under International Research Centres in Singapore Funding Initiativ

A novel convergence enhancement method based on Online Dimension Reduction Optimization

Iterative steady-state solvers are widely used in computational fluid dynamics. Unfortunately, it is difficult to obtain steady-state solution for unstable problem caused by physical instability and numerical instability. Optimization is a better choice for solving unstable problem because steady-state solution is always the extreme point of optimization regardless of whether the problem is unstable or ill-conditioned, but it is difficult to solve partial differential equations (PDEs) due to too many optimization variables. In this study, we propose an Online Dimension Reduction Optimization (ODRO) method to enhance the convergence of the traditional iterative method to obtain the steady-state solution of unstable problem. This method performs proper orthogonal decomposition (POD) on the snapshots collected from a few iteration steps, optimizes PDE residual in the POD subspace to get a solution with lower residual, and then continues to iterate with the optimized solution as the initial value, repeating the above three steps until the residual converges. Several typical cases show that the proposed method can efficiently calculate the steady-state solution of unstable problem with both the high efficiency and robustness of the iterative method and the good convergence of the optimization method. In addition, this method is easy to implement in almost any iterative solver with minimal code modification

Evidence of Ising pairing in superconducting NbSe2_2 atomic layers

Two-dimensional transition metal dichalcogenides with strong spin-orbit interactions and valley-dependent Berry curvature effects have attracted tremendous recent interests. Although novel single-particle and excitonic phenomena related to spin-valley coupling have been extensively studied, effects of spin-momentum locking on collective quantum phenomena remain unexplored. Here we report an observation of superconducting monolayer NbSe$_2$ with an in-plane upper critical field over six times of the Pauli paramagnetic limit by magneto-transport measurements. The effect can be understood in terms of the competing Zeeman effect and large intrinsic spin-orbit interactions in non-centrosymmetric NbSe$_2$ monolayers, where the electronic spin is locked to the out-of-plane direction. Our results provide a strong evidence of unconventional Ising pairing protected by spin-momentum locking and open up a new avenue for studies of non-centrosymmetric superconductivity with unique spin and valley degrees of freedom in the exact two-dimensional limit

A bibliometric analysis of research related to ocean circulation

This study is a bibliometric analysis on ocean circulation-related research for the period 1991-2005. Selected documents included "ocean circulation, sea circulation, seas circulation, marine circulation, and circulation ocean" as a part of the title, abstract or keywords

Cholestasis induces reversible accumulation of periplakin in mouse liver

Abstract Background Periplakin (PPL) is a rod-shaped cytolinker protein thought to connect cellular adhesion junctional complexes to cytoskeletal filaments. PPL serves as a structural component of the cornified envelope in the skin and interacts with various types of proteins in cultured cells; its level decreases dramatically during tumorigenic progression in human epithelial tissues. Despite these intriguing observations, the physiological roles of PPL, especially in non-cutaneous tissues, are still largely unknown. Because we observed a marked fluctuation of PPL expression in mouse liver in association with the bile acid receptor farnesoid X receptor (FXR) and cholestasis, we sought to characterize the role of PPL in the liver and determine its contributions to the etiology and pathogenesis of cholestasis. Methods Time- and context-dependent expression of PPL in various mouse models of hepatic and renal disorders were examined by immunohistochemistry, western blotting, and quantitative real-time polymerase chain reactions. Results The hepatic expression of PPL was significantly decreased in Fxr −/− mice. In contrast, the expression was dramatically increased during cholestasis, with massive PPL accumulation observed at the boundaries of hepatocytes in wild-type mice. Interestingly, the hepatic accumulation of PPL resulting from cholestasis was reversible. In addition, similar accumulation of PPL at cellular boundaries was found in epithelial cells around renal tubules upon ureteral obstruction. Conclusions PPL may be involved in the temporal accommodation to fluid stasis in different tissues. Further examination of the roles for PPL may lead to the discovery of a novel mechanism for cellular protection by cytolinkers that is applicable to many tissues and in many contexts.http://deepblue.lib.umich.edu/bitstream/2027.42/112610/1/12876_2013_Article_974.pd

Assessing mass-loss and stellar-to-halo mass ratio of satellite galaxies: a galaxy–galaxy lensing approach utilizing DECaLS DR8 data

The galaxy–galaxy lensing technique allows us to measure the subhalo mass of satellite galaxies, studying their mass-loss and evolution within galaxy clusters and providing direct observational validation for theories of galaxy formation. In this study, we use the weak gravitational lensing observations from Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Surveys DR8, in combination with the redMaPPer galaxy cluster catalogue from Sloan Digital Sky Survey (SDSS) DR8 to accurately measure the dark matter halo mass of satellite galaxies. We confirm a significant increase in the stellar-to-halo mass ratio of satellite galaxies with their halo-centric radius, indicating clear evidence of mass-loss due to tidal stripping. Additionally, we find that this mass-loss is strongly dependent on the mass of the satellite galaxies, with satellite galaxies above experiencing more pronounced mass-loss compared to lower mass satellites, reaching 86 per cent at projected halo-centric radius 0.5R200c. The average mass-loss rate, when not considering halo-centric radius, displays a U-shaped variation with stellar mass, with galaxies of approximately exhibiting the least mass-loss, around 60 per cent. We compare our results with state-of-the-art hydrodynamical numerical simulations and find that the satellite galaxy stellar-to-halo mass ratio in the outskirts of galaxy clusters is higher compared to the predictions of the Illustris-TNG project about factor 5. Furthermore, the Illustris-TNG project’s numerical simulations did not predict the observed dependence of satellite galaxy mass-loss rate on satellite galaxy mass

MaNGA DynPop – IV. Stacked total density profile of galaxy groups and clusters from combining dynamical models of integral-field stellar kinematics and galaxy–galaxy lensing

We present the measurement of total and stellar/dark matter decomposed mass density profile around a sample of galaxy groupsand clusters with dynamical masses derived from integral-field stellar kinematics from the MaNGA survey in Paper I and weaklensing derived from the DECaLS imaging survey. Combining the two data sets enables accurate measurement of the radialdensity distribution from several kpc to Mpc scales. Intriguingly, we find that the excess surface density derived from stellarkinematics in the inner region cannot be explained by simply adding an NFW dark matter halo extrapolated from lensingmeasurement at a larger scale to a stellar mass component derived from the NASA-Sloan Atlas (NSA) catalogue. We find that agood fit to both data sets requires a stellar mass normalization about three times higher than that derived from the NSA catalogue,which would require an unrealistically too-heavy initial mass function for stellar mass estimation. If we keep the stellar massnormalization to that of the NSA catalogue but allow a varying inner dark matter density profile, we obtain an asymptotic slopeof γ gnfw = 1.82+0.15−0.25 and γ gnfw = 1.48+0.20 −0.41 for the group bin and the cluster bin, respectively, significantly steeper than the NFWcase. We also compare the total mass inner density slopes with those from TNG300 and find that the values from the simulationare lower than the observation by about 2σ level