94 research outputs found
A Diffusion Weighted Graph Framework for New Intent Discovery
New Intent Discovery (NID) aims to recognize both new and known intents from
unlabeled data with the aid of limited labeled data containing only known
intents. Without considering structure relationships between samples, previous
methods generate noisy supervisory signals which cannot strike a balance
between quantity and quality, hindering the formation of new intent clusters
and effective transfer of the pre-training knowledge. To mitigate this
limitation, we propose a novel Diffusion Weighted Graph Framework (DWGF) to
capture both semantic similarities and structure relationships inherent in
data, enabling more sufficient and reliable supervisory signals. Specifically,
for each sample, we diffuse neighborhood relationships along semantic paths
guided by the nearest neighbors for multiple hops to characterize its local
structure discriminately. Then, we sample its positive keys and weigh them
based on semantic similarities and local structures for contrastive learning.
During inference, we further propose Graph Smoothing Filter (GSF) to explicitly
utilize the structure relationships to filter high-frequency noise embodied in
semantically ambiguous samples on the cluster boundary. Extensive experiments
show that our method outperforms state-of-the-art models on all evaluation
metrics across multiple benchmark datasets. Code and data are available at
https://github.com/yibai-shi/DWGF.Comment: EMNLP 2023 Mai
Enhanced Optoelectronic Response in Bilayer Lateral Heterostructures of Transition Metal Dichalcogenides
Two-dimensional lateral heterojunctions are basic components for low-power
and flexible optoelectronics. In contrast to monolayers, devices based on
few-layer lateral heterostructures could offer superior performance due to
their lower susceptibility to environmental conditions. Here, we report the
controlled synthesis of multi-junction bilayer lateral heterostructures based
on MoS2-WS2 and MoSe2-WSe2, where the hetero-junctions are created via
sequential lateral edge-epitaxy that happens simultaneously in both the first
and the second layer. With respect to their monolayer counterparts, bilayer
lateral heterostructures yield nearly one order of magnitude higher
rectification currents. They also display a clear photovoltaic response, with
short circuit currents ~103 times larger than those extracted from the
monolayers, in addition to room-temperature electroluminescence. The superior
performance of bilayer heterostructures significantly expands the
functionalities of 2D crystals
The role of miRNAs in Behçet’s disease
The symptoms of Behçet’s disease (BD), a multisystemic condition with autoimmune and inflammation as hallmarks, include arthritis, recurring oral and vaginal ulcers, skin rashes and lesions, and involvement of the nervous, gastrointestinal, and vascular systems. Non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs), may be important regulators of inflammation and autoimmune disease. These ncRNAs are essential to the physiological and pathophysiological disease course, and miRNA in particular has received significant attention for its role and function in BD and its potential use as a diagnostic biomarker in recent years. Although promising as therapeutic targets, miRNAs must be studied further to fully comprehend how miRNAs in BD act biologically
Extraordinary Thermoelectric Properties of Topological Surface States in Quantum-Confined Cd3As2 Thin Films
Topological insulators and semimetals have been shown to possess intriguing
thermoelectric properties promising for energy harvesting and cooling
applications. However, thermoelectric transport associated with the Fermi arc
topological surface states on topological Dirac semimetals remains less
explored. In this work, we systematically examine thermoelectric transport in a
series of topological Dirac semimetal Cd3As2 thin films grown by molecular beam
epitaxy. Surprisingly, we find significantly enhanced Seebeck effect and
anomalous Nernst effect at cryogenic temperatures when the Cd3As2 layer is
thin. Combining angle-dependent quantum oscillation analysis,
magnetothermoelectric measurement, transport modelling and first-principles
simulation, we isolate the contributions from bulk and surface conducting
channels and attribute the unusual thermoeletric properties to the topological
surface states. Our analysis showcases the rich thermoelectric transport
physics in quantum-confined topological Dirac semimetal thin films and suggests
new routes to achieving high thermoelectric performance at cryogenic
temperatures
Magnetic field-induced non-trivial electronic topology in Fe3−xGeTe2
The anomalous Hall, Nernst and thermal Hall coefficients of
FeGeTe display several features upon cooling, like a reversal in
the Nernst signal below K pointing to a topological transition (TT)
associated to the development of magnetic spin textures. Since the anomalous
transport variables are related to the Berry curvature, a possible TT might
imply deviations from the Wiedemann-Franz (WF) law. However, the anomalous Hall
and thermal Hall coefficients of FeGeTe are found, within our
experimental accuracy, to satisfy the WF law for magnetic-fields
applied along its inter-layer direction. Surprisingly, large anomalous
transport coefficients are also observed for applied along the planar
\emph{a}-axis as well as along the gradient of the chemical potential, a
configuration that should not lead to their observation due to the absence of
Lorentz force. However, as \emph{a}-axis is increased,
magnetization and neutron scattering indicate just the progressive canting of
the magnetic moments towards the planes followed by their saturation. These
anomalous planar quantities are found to not scale with the component of the
planar magnetization (), showing instead a sharp decrease beyond 4 T which is the field required to align the magnetic moments
along . We argue that locally chiral spin structures, such as
skyrmions, and possibly skyrmion tubes, lead to a field dependent
spin-chirality and hence to a novel type of topological anomalous transport.
Locally chiral spin-structures are captured by our Monte-Carlo simulations
incorporating small Dzyaloshinskii-Moriya and biquadratic exchange
interactions.Comment: 34 pages, 10 figures, submitted to Applied Physics Review
Atomistic characterization of the active-site solvation dynamics of a model photocatalyst
The interactions between the reactive excited state of molecular photocatalysts and surrounding solvent dictate reaction mechanisms and pathways, but are not readily accessible to conventional optical spectroscopic techniques. Here we report an investigation of the structural and solvation dynamics following excitation of a model photocatalytic molecular system [Ir 2 (dimen) 4 ] 2+, where dimen is para-diisocyanomenthane. The time-dependent structural changes in this model photocatalyst, as well as the changes in the solvation shell structure, have been measured with ultrafast diffuse X-ray scattering and simulated with Born-Oppenheimer Molecular Dynamics. Both methods provide direct access to the solute-solvent pair distribution function, enabling the solvation dynamics around the catalytically active iridium sites to be robustly characterized. Our results provide evidence for the coordination of the iridium atoms by the acetonitrile solvent and demonstrate the viability of using diffuse X-ray scattering at free-electron laser sources for studying the dynamics of photocatalysis
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