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Symbrain: A large-scale dataset of MRI images for neonatal brain symmetry analysis

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arXiv 2024年

作者： Gucciardi, Arnaud El Ghazouali, Safouane Venturini, Francesca Groznik, Vida Michelucci, Umberto University of Ljubljana Faculty of Computer and Information Science Ljubljana Slovenia TOELT llc Machine Learning Research and Development LAB Dübendorf Switzerland Institute of Applied Mathematics and Physics Zurich University of Applied Sciences Winterthur Switzerland Faculty of Mathematics Natural Sciences and Information Technologies University of Primorska Koper Slovenia

This paper presents an annotated dataset of brain MRI images designed to advance the field of brain symmetry study. Magnetic resonance imaging (MRI) has gained interest in analyzing brain symmetry in neonatal infants, and challenges remain due to the vast size differences between fetal and adult brains. Classification methods for brain structural MRI use scales and visual cues to assess hemisphere symmetry, which can help diagnose neonatal patients by comparing hemispheres and anatomical regions of interest in the brain. Using the Developing Human Connectome Project dataset, this work presents a dataset comprising cerebral images extracted as slices across selected portions of interest for clinical evaluation . All the extracted images are annotated with the brain’s midline. All the extracted images are annotated with the brain’s midline. From the assumption that a decrease in symmetry is directly related to possible clinical pathologies, the dataset can contribute to a more precise diagnosis because it can be used to train deep learning model application in neonatal cerebral MRI anomaly detection from postnatal infant scans thanks to computer vision. Such models learn to identify and classify anomalies by identifying potential asymmetrical patterns in medical MRI images. Furthermore, this dataset can contribute to the research and development of methods using the relative symmetry of the two brain hemispheres for crucial diagnosis and treatment planning. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetic resonance imaging

Shock consolidation and the corresponding plasticity in nanopowdered Mg

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arXiv 2024年

作者： He, D.B. Wang, M.Y. Bi, W.B. Shang, M. Cai, Y. Deng, L. Zhang, X.M. Tang, J.F. Wang, L. College of Science Hunan Agricultural University Changsha410128 China Laboratoroy of Computational Physics Institute of Applied Physics and Computational Mathematics PO Box 8009 Beijing100088 China The Peac Institute of Multiscale Sciences Sichuan Chengdu610207 China

Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials. A thorough investigation of the shock deformation of powder materials is of great engineering signicance. Deformation twinning plays a vital role in accommodating plastic deformation of np-Mg which is hexagonal close packed (hcp) metals, but its mechanisms are still unsettled under high strain rate shock compression. Here we combine nonequilibrium molecular dynamics (NEMD) simulations and X-ray diffraction (XRD) simulation methods to investigate the deformation twinning and pore compaction in shock-compressed np-Mg. Significant anisotropy and strong dependence on crystallographic orientation are presented during shock-induced deformation twinning. During the shock stage, three typical types of twins were firstly induced, namely {112¯1} twin (T1), {112¯2} twin (T2) and {101¯2} twin (T3). Most of them were generated in grains with a larger angle between the impact direction and the c-axis of the lattice. With the increase of strain rate, the types and quantities of twins continued to enrich, but they did not occur when the strain rate (up ≥ 2.0 kms−1) was too high. We also discussed the deformation mechanisms of the three types of twins and found that the coupling of slip and shuffle dominated twin deformation. In addition, void filling occurred due to the interaction of twinning and other plastic deformations, leading to the densification of np-Mg. During the release stage, an interesting reverse change was observed, where the twins produced by the impact receded, and twins were produced in grains that were previously difficult to produce. Copyright © 2024, The Authors. All rights reserved.

关键词： Plastic deformation

SUBDIFFERENTIALLY POLYNOMIALLY BOUNDED FUNCTIONS AND GAUSSIAN SMOOTHING-BASED ZEROTH-ORDER OPTIMIZATION ∗

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arXiv 2024年

作者： Lei, Ming Pong, Ting Kei Sun, Shuqin Yue, Man-Chung College of Applied Mathematics Chengdu University of Information Technology Chengdu China Department of Applied Mathematics The Hong Kong Polytechnic University Hong Kong Key Laboratory of Optimization Theory and Applications China West Normal University of Sichuan Province School of Mathematics Education China West Normal University Nanchong China Musketeers Foundation Institute of Data Science Department of Data and Systems Engineering The University of Hong Kong Hong Kong

We study the class of subdifferentially polynomially bounded (SPB) functions, which is a rich class of locally Lipschitz functions that encompasses all Lipschitz functions, all gradient- or Hessian-Lipschitz functions, and even some non-smooth locally Lipschitz functions. We show that SPB functions are compatible with Gaussian smoothing (GS), in the sense that the GS of any SPB function is well-defined and satisfies a descent lemma akin to gradient-Lipschitz functions, with the Lipschitz constant replaced by a polynomial function. Leveraging this descent lemma, we propose GS-based zeroth-order optimization algorithms with an adaptive stepsize strategy for minimizing SPB functions, and analyze their convergence rates with respect to both relative and absolute stationarity measures. Finally, we also establish the iteration complexity for achieving a (δ, ϵ)-approximate stationary point, based on a novel quantification of Goldstein stationarity via the GS gradient that could be of independent interest. Copyright © 2024, The Authors. All rights reserved.

关键词： Gaussian distribution

g-expectation of distributions

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Probability, Uncertainty and Quantitative Risk 2022年第4期7卷 385-404页

作者： Mingyu Xu Zuo Quan Xu Xun Yu Zhou School of Mathematical Sciences Fudan UniversityShanghai 200433China Department of Applied Mathematics The Hong Kong Polytechnic UniversityKowloonHong KongChina Department of Industrial Engineering and Operations Research&The Data Science Institute Columbia UniversityNew YorkNY 10027USA

We define g-expectation of a distribution as the infimum of the g-expectations of all the terminal random variables sharing that *** present two special cases for nonlinear g where the g-expectation of distributions can be explicitly *** a related problem,we introduce the notion of law-invariant g-expectation and provide its sufficient *** of application in financial dynamic portfolio choice are supplied.

关键词： BSDE g-expectation Probability distribution Cost efficiency Law-invariance Portfolio selection

Spanning trees in graphs without large bipartite holes

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arXiv 2023年

作者： Han, Jie Hu, Jie Ping, Lidan Wang, Guanghui Wang, Yi Yang, Donglei School of Mathematics and Statistics Center for Applied Mathematics Beijing Institute of Technology Beijing China Center for Combinatorics and LPMC Nankai University Tianjin300071 China School of Mathematics Shandong University China Data Science Institute Shandong University China

We show that for any Ε > 0 and ∆ ∈ N, there exists α > 0 such that for sufficiently large n, every n-vertex graph G satisfying that δ(G) ≥ Εn and e(X, Y) > 0 for every pair of disjoint vertex sets X, Y ⊆ V (G) of size αn contains all spanning trees with maximum degree at most ∆. This strengthens a result of Böttcher et al. Copyright © 2023, The Authors. All rights reserved.

关键词： Trees (mathematics)

Confined colloidal droplets dry to form circular mazes

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arXiv 2025年

作者： Beechey-Newman, Ilaria Kizilova, Natalya Henning, Andreas Andersen Flekkøy, Eirik Grude Eiser, Erika PoreLab Department of Physics Norwegian University of Science and Technology Norway Institute of Aeronautics and Applied Mechanics Warsaw University of Technology Poland Department of Applied Mathematics V.N. Karazin Kharkiv National University Ukraine PoreLab The Njord Centre Department of Physics University of Oslo Norway PoreLab Department of Chemistry Norwegian University of Science and Technology Norway Department of Physics University of Cambridge United Kingdom

During drying, particle-laden sessile droplets will leave so-called coffee-stain rings behind. This phenomenon is well-known and well-understood (Deegan et al., Nature 389,827–829 (1997)). Here we show that when particle-laden droplets confined in a slit are allowed to evaporate very slowly, they do not deposit coffee rings, but form a surprisingly intricate, circular maze-like pattern. We present experiments that illustrate this pattern formation and discuss the factors that determine when such patterns can form. We are not aware of reports of natural examples of the formation of such beautiful patterns under confinement, although it seems likely that they exist. © 2025, CC BY.

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A Unified Approach to Path Planning of Multi-robot Systems Based on Bilevel Coordination Architecture 18th

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A Unified Approach to Path Planning of Multi-robot Systems...

18th Chinese Intelligent Systems Conference, CISC 2022

作者： Zhang, Jian Xiang, Lan Miao, Zhonghua Zhou, Jin Shanghai Institute of Applied Mathematics and Mechanics and School of Mechanics and Engineering Science Shanghai University Shanghai200072 China Department of Physics School of Science Shanghai University Shanghai200444 China School of Mechatronic Engineering and Automation Shanghai University Shanghai200072 China

ISBN: (纸本)9789811962257

In this brief, a unified approach to path planning of multi-robot systems (MRS) is proposed based on bilevel coordination architecture. Such architecture is comprised of the global programming layer and local planning layer, which can be implemented by the improved particle swarm optimization (IPSO) and the dynamic window approach (DWA) respectively. Moreover, the nature and advantages of the proposed path planning algorithm are furthermore verified by the simulation experiments. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Multipurpose robots

Ergodicity for stochastic 2D Boussinesq equations with a highly degenerate pure jump Lévy noise

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arXiv 2025年

作者： Huang, Jianhua Peng, Xuhui Wang, Xue Zhang, Jiangwei College of Science National University of Defense Technology Hunan Changsha410073 China MOE-LCSM School of Mathematics and Statistics Hunan Normal University Hunan Changsha410081 China Institute of Applied Physics and Computational Mathematics Beijing100088 China

This study aims to analyze the ergodicity for stochastic 2D Boussinesq equations and explore the impact of a highly degenerate pure jump Lévy noise acting only in the temperature equation, this noise could appear on a few Fourier modes. By leveraging the equi-continuity of the semigroup—established through Malliavin calculus and an analysis of stochastic calculus—together with the weak irreducibility of the solution process, we prove the existence and uniqueness of the invariant measure. Moreover, we overcome the main challenge of establishing time asymptotic smoothing properties of the Markovian dynamics corresponding to this system by conducting spectral analysis of the Malliavin covariance matrix. Copyright © 2025, The Authors. All rights reserved.

关键词： Differentiation (calculus)

Viscosity in water from first-principles and deep-neural-network simulations

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npj Computational Materials 2022年第1期8卷 1318-1327页

作者： Cesare Malosso Linfeng Zhang Roberto Car Stefano Baroni Davide Tisi SISSA—Scuola Internazionale Superiore di Studi Avanzati 34136TriesteItaly Program in Applied and Computational Mathematics Princeton UniversityPrincetonNJ08544USA DP Technology Beijing100080PR China Department of Chemistry Department of Physicsand Princeton Institute for the Science and Technology of MaterialsPrinceton UniversityPrincetonNJUSA CNR Istituto Officina dei Materiali SISSA Unit34136TriesteItaly

We report on an extensive study of the viscosity of liquid water at near-ambient conditions,performed within the Green-Kubo theory of linear response and equilibrium ab initio molecular dynamics(AIMD),based on density-functional theory(DFT).In order to cope with the long simulation times necessary to achieve an acceptable statistical accuracy,our ab initio approach is enhanced with deep-neural-network potentials(NNP).This approach is first validated against AIMD results,obtained by using the Perdew–Burke–Ernzerhof(PBE)exchange-correlation functional and paying careful attention to crucial,yet often overlooked,aspects of the statistical data ***,we train a second NNP to a dataset generated from the Strongly Constrained and Appropriately Normed(SCAN)*** the error resulting from the imperfect prediction of the melting line is offset by referring the simulated temperature to the theoretical melting one,our SCAN predictions of the shear viscosity of water are in very good agreement with experiments.

关键词： viscosity Strongly ambient