3,560 research outputs found
Quantum Anomalous Hall Effect in Graphene from Rashba and Exchange Effects
We investigate the possibility of realizing quantum anomalous Hall effect in
graphene. We show that a bulk energy gap can be opened in the presence of both
Rashba spin-orbit coupling and an exchange field. We calculate the Berry
curvature distribution and find a non-zero Chern number for the valence bands
and demonstrate the existence of gapless edge states. Inspired by this finding,
we also study, by first principles method, a concrete example of graphene with
Fe atoms adsorbed on top, obtaining the same result.Comment: 4 papges, 5 figure
SeasonDepth: Cross-Season Monocular Depth Prediction Dataset and Benchmark under Multiple Environments
Different environments pose a great challenge to the outdoor robust visual
perception for long-term autonomous driving and the generalization of
learning-based algorithms on different environmental effects is still an open
problem. Although monocular depth prediction has been well studied recently,
there is few work focusing on the robust learning-based depth prediction across
different environments, e.g. changing illumination and seasons, owing to the
lack of such a multi-environment real-world dataset and benchmark. To this end,
the first cross-season monocular depth prediction dataset and benchmark
SeasonDepth is built based on CMU Visual Localization dataset. To benchmark the
depth estimation performance under different environments, we investigate
representative and recent state-of-the-art open-source supervised,
self-supervised and domain adaptation depth prediction methods from KITTI
benchmark using several newly-formulated metrics. Through extensive
experimental evaluation on the proposed dataset, the influence of multiple
environments on performance and robustness is analyzed qualitatively and
quantitatively, showing that the long-term monocular depth prediction is still
challenging even with fine-tuning. We further give promising avenues that
self-supervised training and stereo geometry constraint help to enhance the
robustness to changing environments. The dataset is available on
https://seasondepth.github.io, and benchmark toolkit is available on
https://github.com/SeasonDepth/SeasonDepth.Comment: 19 pages, 13 figure
Unusual cross-shelf transport driven by the changes of wind pattern in a marginal sea
Author Posting. © American Geophysical Union, 2021. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 126(11), (2021): e2021JC017526, https://doi.org/10.1029/2021JC017526.The traditional understanding of the regional circulation in the Northwest Pacific marginal seas is that the Korean Coastal Current flows southward, following the isobaths of 20–50 m. However, an unusual tongue-shaped structure of cold water is observed in satellite SST data in January 2017, indicating a possible offshore spread of cold coastal water into the middle Southern Yellow Sea (SYS). Additional observations, including in situ hydrographic data as well as direct current measurement, also suggest this cross-shelf transport of the Korean Coastal Water in January 2017. Our analysis shows that this flow breaks through the isobaths at ∼37°N, moves southward between 50–75 m, and eventually veers anti-cyclonically at ∼35°N to join the western slope of the SYS. This circulation pattern is further supported by heat budget analysis. Diagnosis of potential vorticity (PV) reveals that the elevated negative PV anomaly imposed by surface wind stress favors this unusual cross-shelf transport. The change of wind pattern, although under a deceasing wind speed condition, plays an important role. This work provides an alternative view of the wintertime circulation pattern and motivates future studies of the variability of the coastal currents over interannual and longer time scales in the SYS.his study was supported by the Shandong Provincial Key Research and Development Program (2019JZZY020713, 2019GHY112057), the National Key Research and Development Program (2016YFC1401406, 2016YFA0600900), the National Natural Science Foundation of China (42076010, 42130403), National Fund Committee-Shandong joint fund (U1706215), the Fundamental Research Funds for the Central Universities (2020042010), and Ocean University of China-Woods Hole Oceanographic Institution Cooperative Research Initiative (24887).2022-05-0
Ethyl 5,8-dibromo-2-dibromomethyl-6,7-dimethoxyquinoline-3-carboxylate
The title compound, C15H13Br4NO4, was obtained via radical bromination reaction of ethyl 6,7-dimethoxy-2-methylquinoline-3-carboxylate and N-bromosuccinimide (NBS) in the presence of benzoyl peroxide (BPO) under photocatalytic conditions. The quinoline ring system is approximately planar with a maximum deviation from the mean plane of 0.035 (1) Å. The dihedral angle between the six-membered rings is 2.33 (2)°. The methoxy O atoms of the two neighboring methoxy groups are in-plane while their methyl C atoms are located on either side of the quinolyl ring plane at distances of −1.207 (1) and 1.223 (1) Å
Mechanical and thermal properties of all-wood biocomposites through controllable dissolution of cellulose with ionic liquid
Dynamic transfer reference point oriented MOEA/D involving local objective-space knowledge
The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.The decomposition-based multi-objective evolutionary algorithm (MOEA/D) has attained excellent performance in solving optimization problems involving multiple conflicting objectives. However, the Pareto optimal front (POF) of many multi-objective optimization problems (MOPs) has irregular properties, which weakens the performance of MOEA/D. To address this issue, we devise a dynamic transfer reference point oriented MOEA/D with local objective-space knowledge (DTR-MOEA/D). The design principle is based on three original and rigorous mechanisms. First, the individuals are projected onto a line segment (two-objective case) or a three-dimensional plane (three-objective case) after being normalized in the objective space. The line segment or the plane is divided into three different regions: the central region, the middle region, and the edge region. Second, a dynamic transfer criterion of reference point is developed based on population density relationships in different regions. Third, a strategy of population diversity enhancement guided by local objective-space knowledge is adopted to improve the diversity of the population. Finally, the experimental results conducted on sixteen benchmark MOPs and eight modified MOPs with irregular POF shapes verify that the proposed DTR-MOEA/D has attained a strong competitiveness compared with other representative algorithms
Expression and distribution of HIF-1α, HIF-2α, VEGF, VEGFR-2 and HIMF in the kidneys of Tibetan sheep, plain sheep and goat
Background: The objective of this study was to detect the expression and distribution characteristics of five proteins (the hypoxia-inducible factor 1alpha [HIF-1a], HIF-2a, vascular endothelial growth factor [VEGF], VEGF-2 receptor [VEGFR-2] and hypoxia-induced mitogenic factor [HIMF]) in kidney of Tibetan sheep, plain sheep and goat. The results will provide the basic information for the comparative study of sheep breeds living at different altitudes.Materials and methods: The kidney tissues were collected from healthy adult Tibetan sheep, plain sheep and goats and made into paraffin sections. Histological characteristics were assessed by haematoxylin and eosin staining. Expressions of HIF-1a, HIF-2a, VEGF, VEGFR-2 and HIMF proteins were measured by immunohistochemical staining.Results: Immunohistochemistry results showed that the positive expression signals of HIF-1a, HIF-2a, VEGF and VEGFR-2 were detected in epithelial cells of renal tubules and collecting tubules, renal corpuscles in the kidneys of the three sheep breeds. Positive expression signals of HIMF were detected in epithelial cells of proximal tubules and distal tubules in Tibetan sheep and epithelial cells of distal tubules in goat. Immunostaining intensity of HIF-1a, HIF-2a, VEGF and VEGFR-2 proteins in Tibetan sheep was significantly higher than that in both plain sheep and goat (p < 0.05). Immunostaining intensity of HIMF in Tibetan sheep was higher than goat (p < 0.05). Positive expression signals of HIMF were not detected in plain sheep.Conclusions: The expression and distribution characteristics of HIF-1a, HIF-2a, VEGF, VEGFR-2 and HIMF in the studied kidney tissues suggested that these proteins may be related to the physiological regulation of Tibetan sheep kidney in hypoxia environment, and therefore might be important regulating proteins for Tibetan sheep to adapt to high altitude hypoxia environment
2-(3-Morpholinopropyl)-2,3-dihydro-1H-pyrrolo[3,4-b]quinolin-1-one monohydrate
In the title compound, C18H21N3O2·H2O, the fused-ring system is approximately planar [maximum atomic deviation = 0.028 (3) Å]; the morpholine ring displays a chair conformation. The crystal packing is stabilized by classical intermolecular O—H⋯O and O—H⋯N hydrogen bonds and weak C—H⋯O hydrogen bonds between the organic molecules and the water molecules
Rotational symmetry breaking in superconducting nickelate Nd0.8Sr0.2NiO2 films
The infinite-layer nickelates, isostructural to the high-Tc superconductor
cuprates, have risen as a promising platform to host unconventional
superconductivity and stimulated growing interests in the condensed matter
community. Despite numerous researches, the superconducting pairing symmetry of
the nickelate superconductors, the fundamental characteristic of a
superconducting state, is still under debate. Moreover, the strong electronic
correlation in the nickelates may give rise to a rich phase diagram, where the
underlying interplay between the superconductivity and other emerging quantum
states with broken symmetry is awaiting exploration. Here, we study the angular
dependence of the transport properties on the infinite-layer nickelate
Nd0.8Sr0.2NiO2 superconducting films with Corbino-disk configuration. The
azimuthal angular dependence of the magnetoresistance (R({\phi})) manifests the
rotational symmetry breaking from isotropy to four-fold (C4) anisotropy with
increasing magnetic field, revealing a symmetry breaking phase transition.
Approaching the low temperature and large magnetic field regime, an additional
two-fold (C2) symmetric component in the R({\phi}) curves and an anomalous
upturn of the temperature-dependent critical field are observed simultaneously,
suggesting the emergence of an exotic electronic phase. Our work uncovers the
evolution of the quantum states with different rotational symmetries and
provides deep insight into the global phase diagram of the nickelate
superconductors
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