76 research outputs found
Application of Fuzzy Set Theory in Option of Response Spectra
In order to consider the fuzziness of seismic intensity indecated by zoning map and seismic code in seismic design of structure, an innovative method in option of design spectrum in consideration of fuzziness of regional seismic hazard and site condition is presented herein. The solution of the problem can be divided into two steps: 1. to define and establish a fuzzy set for predicting and judging regional seismic hazard and site condition by applying fuzzy mathematics; 2. further to find out fuzzy vector of design spectrum depending on the fuzzy set of regional seismic hazard and site condition by applying fuzzy comprehensive Judgement theory
Facilitating Graph Neural Networks with Random Walk on Simplicial Complexes
Node-level random walk has been widely used to improve Graph Neural Networks.
However, there is limited attention to random walk on edge and, more generally,
on -simplices. This paper systematically analyzes how random walk on
different orders of simplicial complexes (SC) facilitates GNNs in their
theoretical expressivity. First, on -simplices or node level, we establish a
connection between existing positional encoding (PE) and structure encoding
(SE) methods through the bridge of random walk. Second, on -simplices or
edge level, we bridge edge-level random walk and Hodge -Laplacians and
design corresponding edge PE respectively. In the spatial domain, we directly
make use of edge level random walk to construct EdgeRWSE. Based on the spectral
analysis of Hodge -Laplcians, we propose Hodge1Lap, a permutation
equivariant and expressive edge-level positional encoding. Third, we generalize
our theory to random walk on higher-order simplices and propose the general
principle to design PE on simplices based on random walk and Hodge Laplacians.
Inter-level random walk is also introduced to unify a wide range of simplicial
networks. Extensive experiments verify the effectiveness of our random
walk-based methods.Comment: Accepted by NeurIPS 202
Distance-Restricted Folklore Weisfeiler-Leman GNNs with Provable Cycle Counting Power
The ability of graph neural networks (GNNs) to count certain graph
substructures, especially cycles, is important for the success of GNNs on a
wide range of tasks. It has been recently used as a popular metric for
evaluating the expressive power of GNNs. Many of the proposed GNN models with
provable cycle counting power are based on subgraph GNNs, i.e., extracting a
bag of subgraphs from the input graph, generating representations for each
subgraph, and using them to augment the representation of the input graph.
However, those methods require heavy preprocessing, and suffer from high time
and memory costs. In this paper, we overcome the aforementioned limitations of
subgraph GNNs by proposing a novel class of GNNs -- -Distance-Restricted
FWL(2) GNNs, or -DRFWL(2) GNNs. -DRFWL(2) GNNs use node pairs whose
mutual distances are at most as the units for message passing to balance
the expressive power and complexity. By performing message passing among
distance-restricted node pairs in the original graph, -DRFWL(2) GNNs avoid
the expensive subgraph extraction operations in subgraph GNNs, making both the
time and space complexity lower. We theoretically show that the discriminative
power of -DRFWL(2) GNNs strictly increases as increases. More
importantly, -DRFWL(2) GNNs have provably strong cycle counting power even
with : they can count all 3, 4, 5, 6-cycles. Since 6-cycles (e.g., benzene
rings) are ubiquitous in organic molecules, being able to detect and count them
is crucial for achieving robust and generalizable performance on molecular
tasks. Experiments on both synthetic datasets and molecular datasets verify our
theory. To the best of our knowledge, our model is the most efficient GNN model
to date (both theoretically and empirically) that can count up to 6-cycles
Filling Conversation Ellipsis for Better Social Dialog Understanding
The phenomenon of ellipsis is prevalent in social conversations. Ellipsis
increases the difficulty of a series of downstream language understanding
tasks, such as dialog act prediction and semantic role labeling. We propose to
resolve ellipsis through automatic sentence completion to improve language
understanding. However, automatic ellipsis completion can result in output
which does not accurately reflect user intent. To address this issue, we
propose a method which considers both the original utterance that has ellipsis
and the automatically completed utterance in dialog act and semantic role
labeling tasks. Specifically, we first complete user utterances to resolve
ellipsis using an end-to-end pointer network model. We then train a prediction
model using both utterances containing ellipsis and our automatically completed
utterances. Finally, we combine the prediction results from these two
utterances using a selection model that is guided by expert knowledge. Our
approach improves dialog act prediction and semantic role labeling by 1.3% and
2.5% in F1 score respectively in social conversations. We also present an
open-domain human-machine conversation dataset with manually completed user
utterances and annotated semantic role labeling after manual completion.Comment: Accepted to AAAI 202
Deep Geophysical Anomalies Beneath the Changbaishan Volcano
Subsurface imaging is key to understanding the origin of intraplate volcanoes. The Changbaishan volcano, located about 2,000 km away from the western Pacific subduction zone, has several debated origins. To investigate this, we compared regional seismic tomography with the electrical resistivity results and obtained high-resolution 1D and quasi-2D velocity-depth profiles. We show that the upper mantle is characterized by two anomalies exhibiting distinct features which cannot be explained by the same mechanism. We document a localized low-velocity anomaly atop the 410-km discontinuity, where the P-wave velocity is reduced more than that of the S-wave (i.e., lower Vp/Vs). We propose that this anomaly is caused by the reduction of the effective moduli during the phase transformation of olivine. The other anomaly, located between 300 and 370 km depth, reveals a significant reduction of the S-wave velocity (i.e., higher Vp/Vs), associated with a reduction of the electrical resistivity, altogether consistent with partial melting
A Biomimetic 3D-Self-Forming Approach for Microvascular Scaffolds
The development of science and technology often drew lessons from natural phenomena. Herein, inspired by drying-driven curling of apple peels, hydrogel-based micro-scaled hollow tubules (MHTs) are proposed for biomimicking microvessels, which promote microcirculation and improve the survival of random skin flaps. MHTs with various pipeline structures are fabricated using hydrogel in corresponding shapes, such as Y-branches, anastomosis rings, and triangle loops. Adjustable diameters can be achieved by altering the concentration and cross-linking time of the hydrogel. Based on this rationale, biomimetic microvessels with diameters of 50-500 mu m are cultivated in vitro by coculture of MHTs and human umbilical vein endothelial cells. In vivo studies show their excellent performance to promote microcirculation and improve the survival of random skin flaps. In conclusion, the present work proposes and validifies a biomimetic 3D self-forming method for the fabrication of biomimetic vessels and microvascular scaffolds with high biocompatibility and stability based on hydrogel materials, such as gelatin and hyaluronic acid.Peer reviewe
A Biomimetic 3D-Self-Forming Approach for Microvascular Scaffolds
The development of science and technology often drew lessons from natural phenomena. Herein, inspired by drying-driven curling of apple peels, hydrogel-based micro-scaled hollow tubules (MHTs) are proposed for biomimicking microvessels, which promote microcirculation and improve the survival of random skin flaps. MHTs with various pipeline structures are fabricated using hydrogel in corresponding shapes, such as Y-branches, anastomosis rings, and triangle loops. Adjustable diameters can be achieved by altering the concentration and cross-linking time of the hydrogel. Based on this rationale, biomimetic microvessels with diameters of 50-500 mu m are cultivated in vitro by coculture of MHTs and human umbilical vein endothelial cells. In vivo studies show their excellent performance to promote microcirculation and improve the survival of random skin flaps. In conclusion, the present work proposes and validifies a biomimetic 3D self-forming method for the fabrication of biomimetic vessels and microvascular scaffolds with high biocompatibility and stability based on hydrogel materials, such as gelatin and hyaluronic acid
NO-sGC Pathway Modulates Ca2+ Release and Muscle Contraction in Zebrafish Skeletal Muscle
Vertebrate skeletal muscle contraction and relaxation is a complex process that depends on Ca2+ ions to promote the interaction of actin and myosin. This process can be modulated by nitric oxide (NO), a gas molecule synthesized endogenously by (nitric oxide synthase) NOS isoforms. At nanomolar concentrations NO activates soluble guanylate cyclase (sGC), which in turn activates protein kinase G via conversion of GTP into cyclic GMP. Alternatively, NO post-translationally modifies proteins via S-nitrosylation of the thiol group of cysteine. However, the mechanisms of action of NO on Ca2+ homeostasis during muscle contraction are not fully understood and we hypothesize that NO exerts its effects on Ca2+ homeostasis in skeletal muscles mainly through negative modulation of Ca2+ release and Ca2+ uptake via the NO-sGC-PKG pathway. To address this, we used 5–7 days-post fecundation-larvae of zebrafish, a well-established animal model for physiological and pathophysiological muscle activity. We evaluated the response of muscle contraction and Ca2+ transients in presence of SNAP, a NO-donor, or L-NAME, an unspecific NOS blocker in combination with specific blockers of key proteins of Ca2+ homeostasis. We also evaluate the expression of NOS in combination with dihydropteridine receptor, ryanodine receptor and sarco/endoplasmic reticulum Ca2+ ATPase. We concluded that endogenous NO reduced force production through negative modulation of Ca2+ transients via the NO-sGC pathway. This effect could be reversed using an unspecific NOS blocker or sGC blocker
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