86 research outputs found
Universal digital filtering for denoising volumetric retinal OCT and OCT angiography in 3D shearlet domain
Retinal optical coherence tomography (OCT) and OCT angiography (OCTA) suffer
from the degeneration of image quality due to speckle noise and bulk-motion
noise, respectively. Because the cross-sectional retina has distinct features
in OCT and OCTA B-scans, existing digital filters that can denoise OCT
efficiently are unable to handle the bulk-motion noise in OCTA. In this Letter,
we propose a universal digital filtering approach that is capable of minimizing
both types of noise. Considering the retinal capillaries in OCTA are hard to
differentiate in B-scans while having distinct curvilinear structures in 3D
volumes, we decompose the volumetric OCT and OCTA data with 3D shearlets thus
efficiently separate the retinal tissue and vessels from the noise in this
transform domain. Compared with wavelets and curvelets, the shearlets provide
better representation of the layer edges in OCT and the vasculature in OCTA.
Qualitative and quantitative results show the proposed method outperforms the
state-of-the-art OCT and OCTA denoising methods. Besides, the superiority of 3D
denoising is demonstrated by comparing the 3D shearlet filtering with its 2D
counterpart.Comment: This version has been accepted for publication in Opt. Let
Antiferromagnetic magnonic charge current generation via ultrafast optical excitation
N\'eel spin-orbit torque allows a charge current pulse to efficiently
manipulate the N\'eel vector in antiferromagnets, which offers a unique
opportunity for ultrahigh density information storage with high speed. However,
the reciprocal process of N\'eel spin-orbit torque, the generation of ultrafast
charge current in antiferromagnets has not been demonstrated. Here, we report
the experimental observation of charge current generation in antiferromagnetic
metallic Mn2Au thin films using ultrafast optical excitation. The ultrafast
laser pulse excites antiferromagnetic magnons, resulting in instantaneous
non-equilibrium spin polarization at the antiferromagnetic spin sublattices
with broken spatial symmetry. Then the charge current is generated directly via
spin-orbit fields at the two sublattices, which is termed as the reciprocal
phenomenon of N\'eel spin-orbit torque, and the associated THz emission can be
detected at room temperature. Besides the fundamental significance on the
Onsager reciprocity, the observed magnonic charge current generation in
antiferromagnet would advance the development of antiferromagnetic THz emitter.Comment: 15 pages, 4 figures, this work was submitted to Nature Communications
on Jan. 4th, 2023, now is under the 3rd review proces
MetaGPT: Meta Programming for Multi-Agent Collaborative Framework
Recently, remarkable progress has been made in automated task-solving through
the use of multi-agents driven by large language models (LLMs). However,
existing works primarily focuses on simple tasks lacking exploration and
investigation in complicated tasks mainly due to the hallucination problem.
This kind of hallucination gets amplified infinitely as multiple intelligent
agents interact with each other, resulting in failures when tackling
complicated problems.Therefore, we introduce MetaGPT, an innovative framework
that infuses effective human workflows as a meta programming approach into
LLM-driven multi-agent collaboration. In particular, MetaGPT first encodes
Standardized Operating Procedures (SOPs) into prompts, fostering structured
coordination. And then, it further mandates modular outputs, bestowing agents
with domain expertise paralleling human professionals to validate outputs and
reduce compounded errors. In this way, MetaGPT leverages the assembly line work
model to assign diverse roles to various agents, thus establishing a framework
that can effectively and cohesively deconstruct complex multi-agent
collaborative problems. Our experiments conducted on collaborative software
engineering tasks illustrate MetaGPT's capability in producing comprehensive
solutions with higher coherence relative to existing conversational and
chat-based multi-agent systems. This underscores the potential of incorporating
human domain knowledge into multi-agents, thus opening up novel avenues for
grappling with intricate real-world challenges. The GitHub repository of this
project is made publicly available on: https://github.com/geekan/MetaGP
Magnon-mediated interlayer coupling in an all-antiferromagnetic junction
The interlayer coupling mediated by fermions in ferromagnets brings about
parallel and anti-parallel magnetization orientations of two magnetic layers,
resulting in the giant magnetoresistance, which forms the foundation in
spintronics and accelerates the development of information technology. However,
the interlayer coupling mediated by another kind of quasi-particle, boson, is
still lacking. Here we demonstrate such a static interlayer coupling at room
temperature in an antiferromagnetic junction Fe2O3/Cr2O3/Fe2O3, where the two
antiferromagnetic Fe2O3 layers are functional materials and the
antiferromagnetic Cr2O3 layer serves as a spacer. The N\'eel vectors in the top
and bottom Fe2O3 are strongly orthogonally coupled, which is bridged by a
typical bosonic excitation (magnon) in the Cr2O3 spacer. Such an orthogonally
coupling exceeds the category of traditional collinear interlayer coupling via
fermions in ground state, reflecting the fluctuating nature of the magnons, as
supported by our magnon quantum well model. Besides the fundamental
significance on the quasi-particle-mediated interaction, the strong coupling in
an antiferromagnetic magnon junction makes it a realistic candidate for
practical antiferromagnetic spintronics and magnonics with ultrahigh-density
integration.Comment: 19 pages, 4 figure
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