2,561 research outputs found
Single-photon transport and mechanical NOON state generation in microcavity optomechanics
We investigate the single-photon transport in a single-mode optical fiber
coupled to an optomechanical system in the single-photon strong-coupling
regime. The single-photon transmission amplitude is analytically obtained with
a real-space approach and the effects of thermal noises are studied via
master-equation simulations. The results provide an explicit understanding of
optomechanical interaction and offer a useful guide for manipulating single
photons in optomechanical systems. Based on the theoretical framework, we
further propose a scheme to generate the mechanical NOON states with arbitrary
phonon numbers by measuring the sideband photons. The probability for
generating the NOON state with five phonons is over 0.15.Comment: 13 pages, 6 figure
A Critical Role of Autophagy in Regulating Microglia Polarization in Neurodegeneration
Neuroinflammation and autophagy dysfunction are closely related to the development of neurodegeneration such as Parkinson’s disease (PD). However, the role of autophagy in microglia polarization and neuroinflammation is poorly understood. TNF-α, which is highly toxic to dopaminergic neurons, is implicated as a major mediator of neuroinflammation in PD. In this study, we found that TNF-α resulted in an impairment of autophagic flux in microglia. Concomitantly, an increase of M1 marker (iNOS/NO, IL-1β, and IL-6) expression and reduction of M2 marker (Arginase1, Ym1/2, and IL-10) were observed in TNF-α challenged microglia. Upregulation of autophagy via serum deprivation or pharmacologic activators (rapamycin and resveratrol) promoted microglia polarization toward M2 phenotype, as evidenced by suppressed M1 and elevated M2 gene expression, while inhibition of autophagy with 3-MA or Atg5 siRNA consistently aggravated the M1 polarization induced by TNF-α. Moreover, Atg5 knockdown alone was sufficient to trigger microglia activation toward M1 status. More important, TNF-α stimulated microglia conditioned medium caused neurotoxicity when added to neuronal cells. The neurotoxicity was further aggravated when Atg5 knockdown in BV2 cells but alleviated when microglia pretreatment with rapamycin. Activation of AKT/mTOR signaling may contribute to the changes of autophagy and inflammation as the AKT specific inhibitor perifosine prevented the increase of LC3II (an autophagic marker) in TNF-α stimulated microglia. Taking together, our results demonstrate that TNF-α inhibits autophagy in microglia through AKT/mTOR signaling pathway, and autophagy enhancement can promote microglia polarization toward M2 phenotype and inflammation resolution
Reliable Joint Segmentation of Retinal Edema Lesions in OCT Images
Focusing on the complicated pathological features, such as blurred
boundaries, severe scale differences between symptoms, background noise
interference, etc., in the task of retinal edema lesions joint segmentation
from OCT images and enabling the segmentation results more reliable. In this
paper, we propose a novel reliable multi-scale wavelet-enhanced transformer
network, which can provide accurate segmentation results with reliability
assessment. Specifically, aiming at improving the model's ability to learn the
complex pathological features of retinal edema lesions in OCT images, we
develop a novel segmentation backbone that integrates a wavelet-enhanced
feature extractor network and a multi-scale transformer module of our newly
designed. Meanwhile, to make the segmentation results more reliable, a novel
uncertainty segmentation head based on the subjective logical evidential theory
is introduced to generate the final segmentation results with a corresponding
overall uncertainty evaluation score map. We conduct comprehensive experiments
on the public database of AI-Challenge 2018 for retinal edema lesions
segmentation, and the results show that our proposed method achieves better
segmentation accuracy with a high degree of reliability as compared to other
state-of-the-art segmentation approaches. The code will be released on:
https://github.com/LooKing9218/ReliableRESeg
Intrinsic nonlinear Hall effect and gate-switchable Berry curvature sliding in twisted bilayer graphene
Though the observation of quantum anomalous Hall effect and nonlocal
transport response reveals nontrivial band topology governed by the Berry
curvature in twisted bilayer graphene, some recent works reported nonlinear
Hall signals in graphene superlattices which are caused by the extrinsic
disorder scattering rather than the intrinsic Berry curvature dipole moment. In
this work, we report a Berry curvature dipole induced intrinsic nonlinear Hall
effect in high-quality twisted bilayer graphene devices. We also find that the
application of the displacement field substantially changes the direction and
amplitude of the nonlinear Hall voltages, as a result of a field-induced
sliding of the Berry curvature hotspots. Our work not only proves that the
Berry curvature dipole could play a dominant role in generating the intrinsic
nonlinear Hall signal in graphene superlattices with low disorder densities,
but also demonstrates twisted bilayer graphene to be a sensitive and
fine-tunable platform for second harmonic generation and rectification
Catalytically efficient Ni-NiOₓ-Y₂O₃ interface for medium temperature water-gas shift reaction
The metal-support interfaces between metals and oxide supports have long been studied in catalytic applications, thanks to their significance in structural stability and efficient catalytic activity. The metal-rare earth oxide interface is particularly interesting because these early transition cations have high electrophilicity, and therefore good binding strength with Lewis basic molecules, such as H2O. Based on this feature, here we design a highly efficient composite Ni-Y2O3 catalyst, which forms abundant active Ni-NiOx-Y2O3 interfaces under the water-gas shift (WGS) reaction condition, achieving 140.6 μmolCO gcat-1 s-1 rate at 300 °C, which is the highest activity for Ni-based catalysts. A combination of theory and ex/in situ experimental study suggests that Y2O3 helps H2O dissociation at the Ni-NiOx-Y2O3 interfaces, promoting this rate limiting step in the WGS reaction. Construction of such new interfacial structure for molecules activation holds great promise in many catalytic systems
Effects of Treated Cow Dung Addition on the Strength of Carbon-Bearing Iron Ore Pellets
It is of particular interest to use biomass as an alternative source of fuel in direct-reduction ironmaking to ease the current reliance on fossil fuel energy. The influence of cow dung addition on the strength of carbon-bearing iron ore pellets composed of cow dung, iron ore, anthracite, and bentonite was investigated, the quality of green and dry pellet was evaluated based on FTIR analysis, and the mechanism of strength variation of the reduced pellets was investigated by analysing the phase composition and microstructure using XRD and SEM. The results show that cow dung addition decreased the green pellet strength due to expansion of the amorphous region of the cellulose in the cow dung; however, the dry pellet strength increased substantially. In the process of reduction roasting, it was found that cow dung addition can promote aggregation of iron crystals and increase the density of the pellets, resulting in increased strength of the reduction roasted pellets, while excessive cow dung addition resulted in lower strength
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