3,214 research outputs found
Stressed waveguides with tubular depressed-cladding inscribed in phosphate glasses by femtosecond hollow laser beams
This is the published version. ©Copyright 2012 Optical Society of AmericaWe report on the single-step fabrication of stressed optical waveguides with tubular depressed-refractive-index cladding in phosphate glasses by the use of focused femtosecond hollow laser beams. Tubelike low index regions appear under direct exposure due to material rarefaction following expansion. Strained compacted zones emerged in domains neighboring the tubular track of lower refractive index, and waveguiding occurs mainly within the tube core fabricated by the engineered femtosecond laser beam. The refractive index profile of the optical waveguide was reconstructed from the measured transmitted near-field intensity
ProtoEM: A Prototype-Enhanced Matching Framework for Event Relation Extraction
Event Relation Extraction (ERE) aims to extract multiple kinds of relations
among events in texts. However, existing methods singly categorize event
relations as different classes, which are inadequately capturing the intrinsic
semantics of these relations. To comprehensively understand their intrinsic
semantics, in this paper, we obtain prototype representations for each type of
event relation and propose a Prototype-Enhanced Matching (ProtoEM) framework
for the joint extraction of multiple kinds of event relations. Specifically,
ProtoEM extracts event relations in a two-step manner, i.e., prototype
representing and prototype matching. In the first step, to capture the
connotations of different event relations, ProtoEM utilizes examples to
represent the prototypes corresponding to these relations. Subsequently, to
capture the interdependence among event relations, it constructs a dependency
graph for the prototypes corresponding to these relations and utilized a Graph
Neural Network (GNN)-based module for modeling. In the second step, it obtains
the representations of new event pairs and calculates their similarity with
those prototypes obtained in the first step to evaluate which types of event
relations they belong to. Experimental results on the MAVEN-ERE dataset
demonstrate that the proposed ProtoEM framework can effectively represent the
prototypes of event relations and further obtain a significant improvement over
baseline models.Comment: Work in progres
An In-Context Schema Understanding Method for Knowledge Base Question Answering
The Knowledge Base Question Answering (KBQA) task aims to answer natural
language questions based on a given knowledge base. As a kind of common method
for this task, semantic parsing-based ones first convert natural language
questions to logical forms (e.g., SPARQL queries) and then execute them on
knowledge bases to get answers. Recently, Large Language Models (LLMs) have
shown strong abilities in language understanding and may be adopted as semantic
parsers in such kinds of methods. However, in doing so, a great challenge for
LLMs is to understand the schema of knowledge bases. Therefore, in this paper,
we propose an In-Context Schema Understanding (ICSU) method for facilitating
LLMs to be used as a semantic parser in KBQA. Specifically, ICSU adopts the
In-context Learning mechanism to instruct LLMs to generate SPARQL queries with
examples. In order to retrieve appropriate examples from annotated
question-query pairs, which contain comprehensive schema information related to
questions, ICSU explores four different retrieval strategies. Experimental
results on the largest KBQA benchmark, KQA Pro, show that ICSU with all these
strategies outperforms that with a random retrieval strategy significantly
(from 12\% to 78.76\% in accuracy)
Continuous extremal optimization for Lennard-Jones Clusters
In this paper, we explore a general-purpose heuristic algorithm for finding
high-quality solutions to continuous optimization problems. The method, called
continuous extremal optimization(CEO), can be considered as an extension of
extremal optimization(EO) and is consisted of two components, one is with
responsibility for global searching and the other is with responsibility for
local searching. With only one adjustable parameter, the CEO's performance
proves competitive with more elaborate stochastic optimization procedures. We
demonstrate it on a well known continuous optimization problem: the
Lennerd-Jones clusters optimization problem.Comment: 5 pages and 3 figure
Nested Event Extraction upon Pivot Element Recogniton
Nested Event Extraction (NEE) aims to extract complex event structures where
an event contains other events as its arguments recursively. Nested events
involve a kind of Pivot Elements (PEs) that simultaneously act as arguments of
outer events and as triggers of inner events, and thus connect them into nested
structures. This special characteristic of PEs brings challenges to existing
NEE methods, as they cannot well cope with the dual identities of PEs.
Therefore, this paper proposes a new model, called PerNee, which extracts
nested events mainly based on recognizing PEs. Specifically, PerNee first
recognizes the triggers of both inner and outer events and further recognizes
the PEs via classifying the relation type between trigger pairs. In order to
obtain better representations of triggers and arguments to further improve NEE
performance, it incorporates the information of both event types and argument
roles into PerNee through prompt learning. Since existing NEE datasets (e.g.,
Genia11) are limited to specific domains and contain a narrow range of event
types with nested structures, we systematically categorize nested events in
generic domain and construct a new NEE dataset, namely ACE2005-Nest.
Experimental results demonstrate that PerNee consistently achieves
state-of-the-art performance on ACE2005-Nest, Genia11 and Genia13
IL-22 Signaling Contributes to West Nile Encephalitis Pathogenesis
The Th17 cytokine, IL-22, regulates host immune responses to extracellular pathogens. Whether IL-22 plays a role in viral infection, however, is poorly understood. We report here that Il22-/- mice were more resistant to lethal West Nile virus (WNV) encephalitis, but had similar viral loads in the periphery compared to wild type (WT) mice. Viral loads, leukocyte infiltrates, proinflammatory cytokines and apoptotic cells in the central nervous system (CNS) of Il22-/- mice were also strikingly reduced. Further examination showed that Cxcr2, a chemokine receptor that plays a non-redundant role in mediating neutrophil migration, was significantly reduced in Il22-/- compared to WT leukocytes. Expression of Cxcr2 ligands, cxcl1 and cxcl5, was lower in Il22-/- brains than wild type mice. Correspondingly, neutrophil migration from the blood into the brain was attenuated following lethal WNV infection of Il22-/- mice. Our results suggest that IL-22 signaling exacerbates lethal WNV encephalitis likely by promoting WNV neuroinvasion
Hierarchical domain structure and extremely large wall current in epitaxial BiFeO3 thin films
Funding: J.F.S. acknowledges the financial support of the Strategic Priority Research Program of the Chinese Academy of Sciences (grant number XDB07030200).Erasable electrical conductive domain walls in an insulating ferroelectric matrix provide novel functionalities for applications in logic and memory devices. The crux of such success requires sufficiently high wall currents to drive high‐speed and high‐power nanodevices. This work provides an appealing strategy to increase the current by two orders of magnitude through the careful selection of current flowing paths along the charged walls. The dense walls come into form through the hierarchical evolution of the 71°, 109°, and 180° domains of epitaxial BiFeO3 films in a planar‐geometry ferroelectric resistance‐switching memory cell. The engineered films grown on SrTiO3 and GdScO3 substrates allow the observation of detailed local configurations and the evolution of the different domain types using vector piezo‐force microscopy. The higher local electrical conductivity near the charged domain walls is identified by conductive atomic‐force microscopy. It is shown that 180° domain reversal proceeds by three‐step 71° rotations of the pristine domains. Surprisingly, a maximum current of ≈300 nA is observed for current paths along charge‐uncompensated head‐to‐head hierarchical domain walls connecting the two electrodes on the film surface. Furthermore, the achievable current level can be conveniently controlled by varying the relative directions of the initial polarization and the applied field.PostprintPeer reviewe
The complete genome of Zunongwangia profunda SM-A87 reveals its adaptation to the deep-sea environment and ecological role in sedimentary organic nitrogen degradation
<p>Abstract</p> <p>Background</p> <p><it>Zunongwangia profunda </it>SM-A87, which was isolated from deep-sea sediment, is an aerobic, gram-negative bacterium that represents a new genus of <it>Flavobacteriaceae</it>. This is the first sequenced genome of a deep-sea bacterium from the phylum <it>Bacteroidetes</it>.</p> <p>Results</p> <p>The <it>Z. profunda </it>SM-A87 genome has a single 5 128 187-bp circular chromosome with no extrachromosomal elements and harbors 4 653 predicted protein-coding genes. SM-A87 produces a large amount of capsular polysaccharides and possesses two polysaccharide biosynthesis gene clusters. It has a total of 130 peptidases, 61 of which have signal peptides. In addition to extracellular peptidases, SM-A87 also has various extracellular enzymes for carbohydrate, lipid and DNA degradation. These extracellular enzymes suggest that the bacterium is able to hydrolyze organic materials in the sediment, especially carbohydrates and proteinaceous organic nitrogen. There are two clustered regularly interspaced short palindromic repeats in the genome, but their spacers do not match any sequences in the public sequence databases. SM-A87 is a moderate halophile. Our protein isoelectric point analysis indicates that extracellular proteins have lower predicted isoelectric points than intracellular proteins. SM-A87 accumulates organic osmolytes in the cell, so its extracelluar proteins are more halophilic than its intracellular proteins.</p> <p>Conclusion</p> <p>Here, we present the first complete genome of a deep-sea sedimentary bacterium from the phylum <it>Bacteroidetes</it>. The genome analysis shows that SM-A87 has some common features of deep-sea bacteria, as well as an important capacity to hydrolyze sedimentary organic nitrogen.</p
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