716 research outputs found
High-resolution carbonate stratigraphy of IMAGES core MD972151 from South China Sea
High-resolution carbonate stratigraphy of the deep-sea core MD972151 from the southwestern South China Sea shows millennial-scale variability similar to oxygen isotopic fluctuations recorded in ice cores from Greenland. In a long term of glacial-interglacial scale, carbonate contents in the interglacial time (up to 25 % by weight) were higher than that in the glacial periods (5-15 % by weight). Even for the last glacial, carbonate contents are relatively high in the interstadial events and low in the stadial horizons. This demonstrates clearly that carbonate content in the continental slope above the lysocline in the southwestern South China Sea is primarily controlled by dilution of terrigenous inputs, which in turn is due to sea-level fluctuations in response to changes of ice volume in high latitude regions
The South China Sea is not a mini-Atlantic: plate-edge rifting vs intra-plate rifting
Ā© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wang, P., Huang, C., Lin, J., Jian, Z., Sun, Z., & Zhao, M. The South China Sea is not a mini-Atlantic: plate-edge rifting vs intra-plate rifting. National Science Review, 6(5), (2019): 902-913, doi:10.1093/nsr/nwz135.The South China Sea, as āa non-volcanic passive margin basinā in the Pacific, has often been considered as a small-scale analogue of the Atlantic. The recent ocean drilling in the northern South China Sea margin found, however, that the Iberian model of non-volcanic rifted margin from the Atlantic does not apply to the South China Sea. In this paper, we review a variety of rifted basins and propose to discriminate two types of rifting basins: plate-edge type such as the South China Sea and intra-plate type like the Atlantic. They not only differ from each other in structure, formation process, lifespan and geographic size, but also occur at different stages of the Wilson cycle. The intra-plate rifting occurred in the Mesozoic and gave rise to large oceans, whereas the plate-edge rifting took place mainly in the mid-Cenozoic, with three-quarters of the basins concentrated in the Western Pacific. As a member of the Western Pacific system of marginal seas, the South China Sea should be studied not in isolation on its origin and evolution, but in a systematic context to include also its neighboring counterparts.This work was supported by the National Natural Science Foundation of China as a part of the āSouth China Sea Deepā Project (91128000)
Cytotoxicity in the Age of Nano: The Role of Fourth Period Transition Metal Oxide Nanoparticle Physicochemical Properties
A clear understanding of physicochemical factors governing nanoparticle toxicity is still in its infancy. We used a systematic approach to delineate physicochemical properties of nanoparticles that govern cytotoxicity. The cytotoxicity of fourth period metal oxide nanoparticles (NPs): TiO2, Cr2O3, Mn2O3, Fe2O3, NiO, CuO, and ZnO increases with the atomic number of the transition metal oxide. This trend was not cell-type specific, as observed in non-transformed human lung cells (BEAS-2B) and human bronchoalveolar carcinoma-derived cells (A549). Addition of NPs to the cell culture medium did not significantly alter pH. Physiochemical properties were assessed to discover the determinants of cytotoxicity: (1) point-of-zero charge (PZC) (i.e., isoelectric point) described the surface charge of NPs in cytosolic and lysosomal compartments; (2) relative number of available binding sites on the NP surface quantified by X-ray photoelectron spectroscopy was used to estimate the probability of biomolecular interactions on the particle surface; (3) band-gap energy measurements to predict electron abstraction from NPs which might lead to oxidative stress and subsequent cell death; and (4) ion dissolution. Our results indicate that cytotoxicity is a function of particle surface charge, the relative number of available surface binding sites, and metal ion dissolution from NPs. These findings provide a physicochemical basis for both risk assessment and the design of safer nanomaterials
Deep Learning for Spin-Orbit Torque Characterizations with a Projected Vector Field Magnet
Spin-orbit torque characterizations on magnetic heterostructures with
perpendicular anisotropy are demonstrated on a projected vector field magnet
via hysteresis loop shift measurement and harmonic Hall measurement with planar
Hall correction. Accurate magnetic field calibration of the vector magnet is
realized with the help of deep learning models, which are able to capture the
nonlinear behavior between the generated magnetic field and the currents
applied to the magnet. The trained models can successfully predict the applied
current combinations under the circumstances of magnetic field scans, angle
scans, and hysteresis loop shift measurements. The validity of the models is
further verified, complemented by the comparison of the spin-orbit torque
characterization results obtained from the deep-learning-trained vector magnet
system with those obtained from a conventional setup comprised of two separated
electromagnets. The damping-like spin-orbit torque (DL-SOT) efficiencies
(||) extracted from the vector magnet and the traditional measurement
configuration are consistent, where || 0.22 for amorphous W
and || 0.02 for -W. Our work provides an advanced
method to meticulously control a vector magnet and to conveniently perform
various spin-orbit torque characterizations
EgoPCA: A New Framework for Egocentric Hand-Object Interaction Understanding
With the surge in attention to Egocentric Hand-Object Interaction (Ego-HOI),
large-scale datasets such as Ego4D and EPIC-KITCHENS have been proposed.
However, most current research is built on resources derived from third-person
video action recognition. This inherent domain gap between first- and
third-person action videos, which have not been adequately addressed before,
makes current Ego-HOI suboptimal. This paper rethinks and proposes a new
framework as an infrastructure to advance Ego-HOI recognition by Probing,
Curation and Adaption (EgoPCA). We contribute comprehensive pre-train sets,
balanced test sets and a new baseline, which are complete with a
training-finetuning strategy. With our new framework, we not only achieve
state-of-the-art performance on Ego-HOI benchmarks but also build several new
and effective mechanisms and settings to advance further research. We believe
our data and the findings will pave a new way for Ego-HOI understanding. Code
and data are available at https://mvig-rhos.com/ego_pcaComment: ICCV 202
A balanced homodyne detector for high-rate Gaussian-modulated coherent-state quantum key distribution
We discuss excess noise contributions of a practical balanced homodyne
detector in Gaussian-modulated coherent-state (GMCS) quantum key distribution
(QKD). We point out the key generated from the original realistic model of GMCS
QKD may not be secure. In our refined realistic model, we take into account
excess noise due to the finite bandwidth of the homodyne detector and the
fluctuation of the local oscillator. A high speed balanced homodyne detector
suitable for GMCS QKD in the telecommunication wavelength region is built and
experimentally tested. The 3dB bandwidth of the balanced homodyne detector is
found to be 104MHz and its electronic noise level is 13dB below the shot noise
at a local oscillator level of 8.5*10^8 photon per pulse. The secure key rate
of a GMCS QKD experiment with this homodyne detector is expected to reach
Mbits/s over a few kilometers.Comment: 22 pages, 11 figure
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