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Personalized and uncertainty-aware coronary hemodynamics simulations: From Bayesian estimation to improved multi-fidelity uncertainty quantification

arXiv

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arXiv 2024年

作者： Menon, Karthik Zanoni, Andrea Khan, Owais Geraci, Gianluca Nieman, Koen Schiavazzi, Daniele E. Marsden, Alison L. Stanford School of Medicine StanfordCA United States Institute for Computational and Mathematical Engineering Stanford University StanfordCA United States Department of Electrical Computer and Biomedical Engineering Toronto Metropolitan University TorontoON Canada Center for Computing Research Sandia National Laboratories AlbuquerqueNM United States Division of Cardiovascular Medicine Stanford School of Medicine StanfordCA United States Department of Radiology Stanford School of Medicine StanfordCA United States Department of Applied and Computational Mathematics and Statistics University of Notre Dame Notre DameIN United States Department of Bioengineering Stanford University StanfordCA United States

Background: Non-invasive simulations of coronary hemodynamics have improved clinical risk stratification and treatment outcomes for coronary artery disease, compared to relying on anatomical imaging alone. However, simulations typically use empirical approaches to distribute total coronary flow amongst the arteries in the coronary tree, which ignores patient variability, the presence of disease, and other clinical factors. Further, uncertainty in the clinical data often remains unaccounted for in the modeling pipeline. Objective: We present an end-to-end uncertainty-aware pipeline to (1) personalize coronary flow simulations by incorporating vessel-specific coronary flows as well as cardiac function;and (2) predict clinical and biomechanical quantities of interest with improved precision, while accounting for uncertainty in the clinical data. Methods: We assimilate patient-specific measurements of myocardial blood flow from clinical CT myocardial perfusion imaging to estimate branch-specific coronary artery flows. Simulated noise in the clinical data is used to estimate the joint posterior distributions of the model parameters using adaptive Markov Chain Monte Carlo sampling. Additionally, the posterior predictive distribution for the relevant quantities of interest is determined using a new approach combining multi-fidelity Monte Carlo estimation with non-linear, data-driven dimensionality reduction. This leads to improved correlations between high- and low-fidelity model outputs. Results: Our framework accurately recapitulates clinically measured cardiac function as well as branch-specific coronary flows under measurement noise uncertainty. We observe substantial reductions in confidence intervals for estimated quantities of interest compared to single-fidelity Monte Carlo estimation and state-of-the-art multi-fidelity Monte Carlo methods. This holds especially true for quantities of interest that showed limited correlation between the low- and high-fidelity model

关键词： Monte Carlo methods

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Optimal undirectional amplification induced by optical gain in optomechanical systems

arXiv

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arXiv 2019年

作者： Song, L.N. Zheng, Qiang Xu, Xun-Wei Jiang, Cheng Li, Yong Beijing Computational Science Research Center Beijing100193 China School of Mathematics Guizhou Normal University Guiyang550001 China Department of Applied Physics East China Jiaotong University Nanchang330013 China School of Physics and Electronic Electrical Engineering Huaiyin Normal University Huai’an223300 China Synergetic Innovation Center for Quantum Effects and Applications Hunan Normal University Changsha410081 China

We propose a three-mode optomechanical system to realize optical nonreciprocal transmission with unidirectional amplification, where the system consists of two coupled cavities and one mechanical resonator which interacts with only one of the cavities. Additionally, the optical gain is introduced into the optomechanical cavity. It is found that for a strong optical input, the optical transmission coefficient can be greatly amplified in a particular direction and suppressed in the opposite direction. The expressions of the optimal transmission coefficient and the corresponding isolation ratio are given analytically. Our results pave a way to design high-quality nonreciprocal devices based on optomechanical *** Codes 81V80 Copyright © 2019, The Authors. All rights reserved.

关键词： Light transmission

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Rabi antenna using microstrip add-drop multiplexer for electron warp speed investigation

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Chinese Optics Letters 2022年第7期20卷 80-87页

作者： Somchat Sonasang Prakasit Prabpal Piya Sirikan Pratimakorn Hakaew Nhat Truong Pham Preecha Yupapin Kanad Ray Sarawoot Boonkirdram Department of Electronic Technology Faculty of Industrial TechnologyNakhon Phanom UniversityNakhon Phanom 48000Thailand Department of Electrical Technology School of Industrial TechnologySakonnakhon Technical CollegeInstitute of Vocational Education Northeastern Region 2Sakonnakhorn 47000Thailand Division of Computational Mechatronics Institute for Computational ScienceTon Duc Thang UniversityHo Chi Minh City 72915Vietnam Faculty of Electrical and Electronics Engineering Ton Duc Thang UniversityHo Chi Minh City 72915Vietnam Amity School of Applied Sciences Amity University RajasthanJaipurIndia Faubert Lab Universitéde MontréalH3T 1P1 MontréalCanada Facultad de CienciasFisico-Matematicas Benemérita Universidad Autónoma de PueblaAv.San Claudio y Av.18 surCol.San Manuel Ciudad UniversitariaPuebla Pue 72570Mexico Program of Electrical and Electronics Faculty of Industrial TechnologySakon Nakhon Rajabhat UniversitySakon Nakhon 47000Thailand

This work presents experimental results of Rabi antenna characteristics using the coupled line microstrip *** was constructed by a modified coupled line microstrip four-port network,which is known as an add-drop *** driven AC input enters the device via an input port using the suitable frequency and coupled line microstrip ring *** multilevel system is generated by a wave-particle aspect before the two-level system is *** the resonance,the transitions of the states induce the energy called whispering gallery mode(WGM)at the circuit center,which is the squeezed *** generated electron oscillation within the WGM envelope oscillated by the frequency is known as the Rabi *** the successive filtering with continuous AC input via the selected port,the electron cloud warp speed can be generated and achieved inside the two-level *** constructed microstrip ring radius is 25 mm,and the experimental results of the Rabi antenna characteristics are in good agreement with the simulation *** obtained resonant antenna oscillation frequency is 2.103 *** electron cloud warp speed of 1.100c and time dilation of 0.006μs are obtained.

关键词： integrated photonics waveguide microwave photonics Rabi antenna

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Kernel-based parameter estimation of dynamical systems with unknown observation functions

arXiv

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arXiv 2020年

作者： Lindenbaum, Ofir Sagiv, Amir Mishne, Gal Talmon, Ronen Program in Applied Mathematics Yale University 51 Prospect Street New HavenCT06511 United States Department of Applied Physics and Applied Mathematics Columbia University 500 West 120th Street New YorkNY10027 United States Halicioglu Data Science Institute UC San Diego 9500 Gilman Drive MS0555 United States SDSC 215E San DiegoCA92093-0555 United States Faculty of Electrical Engineering Technion - Israel Institute of Technology Haifa32000 Israel

A low-dimensional dynamical system is observed in an experiment as a high-dimensional signal;for example, a video of a chaotic pendulums system. Assuming that we know the dynamical model up to some unknown parameters, can we estimate the underlying system's parameters by measuring its time-evolution only once? The key information for performing this estimation lies in the temporal inter-dependencies between the signal and the model. We propose a kernel-based score to compare these dependencies. Our score generalizes a maximum likelihood estimator for a linear model to a general nonlinear setting in an unknown feature space. We estimate the system's underlying parameters by maximizing the proposed score. We demonstrate the accuracy and efficiency of the method using two chaotic dynamical systems - the double pendulum and the Lorenz'63 model. © 2020, CC BY.

关键词： Maximum likelihood estimation

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Symmetry-Governed Dynamics of Magnetic Skyrmions Under Field Pulses

arXiv

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arXiv 2024年

作者： Kuchkin, Vladyslav M. Barton-Singer, Bruno Bessarab, Pavel F. Kiselev, Nikolai S. Department of Physics and Materials Science University of Luxembourg LuxembourgL-1511 Luxembourg Institute of Applied and Computational Mathematics Foundation for Research and Technology - Hellas Heraklion700 13 Greece Science Institute University of Iceland Reykjavík107 Iceland Department of Physics and Electrical Engineering Linnaeus University KalmarSE-39231 Sweden Peter Grünberg Institute Forschungszentrum Jülich and JARA Jülich52425 Germany

Topological magnetic solitons, such as skyrmions, exhibit intriguing particle-like properties that make them attractive for fundamental research and practical applications. While many magnetic systems can host skyrmions as statically stable configurations, chiral magnets stand out for their ability to accommodate a wide diversity of skyrmions with arbitrary topological charges and varied morphologies. Despite extensive investigation, a complete understanding of chiral magnetic skyrmions has remained elusive. We present a classification of all chiral skyrmions, demonstrating three classes based on their response to external magnetic field pulses: stationary, translating, and rotating. We highlight the role of magnetic texture symmetry in this classification. Skyrmions with varied dynamics offer avenues for exploring phenomena like skyrmion-skyrmion scattering that might be crucial for future applications. Copyright © 2024, The Authors. All rights reserved.

关键词： Textures

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Phase behavior of colloidal superballs: Shape interpolation from spheres to cubes

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Physical Review E 2010年第6期81卷 061105-061105页

作者： Robert D. Batten Frank H. Stillinger Salvatore Torquato Department of Chemical Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Department of Physics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Science Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544 USA School of Natural Sciences Institute for Advanced Study Princeton New Jersey 08544 USA

The phase behavior of hard superballs is examined using molecular dynamics within a deformable periodic simulation box. A superball’s interior is defined by the inequality |x|2q+|y|2q+|z|2q≤1, which provides a versatile family of convex particles (q≥0.5) with cubelike and octahedronlike shapes as well as concave particles (q<0.5) with octahedronlike shapes. Here, we consider the convex case with a deformation parameter q between the sphere point (q=1) and the cube (q=∞). We find that the asphericity plays a significant role in the extent of cubatic ordering of both the liquid and crystal phases. Calculation of the first few virial coefficients shows that superballs that are visually similar to cubes can have low-density equations of state closer to spheres than to cubes. Dense liquids of superballs display cubatic orientational order that extends over several particle lengths only for large q. Along the ordered, high-density equation of state, superballs with 1

关键词： Spheres

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25th Annual computational Neuroscience Meeting CNS-2016, Seogwipo City, South Korea, July 2-7, 2016 Abstracts

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BMC NEUROSCIENCE 2016年第1期17卷 1-112页

作者： [Anonymous] Computational Neurobiology Laboratory The Salk Institute for Biological Studies San Diego USA UNIC CNRS Gif sur Yvette France The European Institute for Theoretical Neuroscience (EITN) Paris France ATR Computational Neuroscience Laboratories Kyoto Japan Krembil Research Institute University Health Network Toronto Canada Department of Physiology University of Toronto Toronto Canada Department of Medicine (Neurology) University of Toronto Toronto Canada Department of Physics University of New Hampshire Durham USA Department of Neurophysiology Nencki Institute of Experimental Biology Warsaw Poland Department of Theory Wigner Research Centre for Physics of the Hungarian Academy of Sciences Budapest Hungary Department of Mathematical Sciences KAIST Daejoen Republic of Korea Department of Mathematics University of Houston Houston USA Department of Biochemistry & Cell Biology and Institute of Biosciences and Bioengineering Rice University Houston USA Department of Biology and Biochemistry University of Houston Houston USA Grupo de Neurocomputación Biológica Dpto. de Ingeniería Informática Escuela Politécnica Superior Universidad Autónoma de Madrid Madrid Spain Department of Biological Sciences University of Southern California Los Angeles USA Center for Neuroscience Korea Institute of Science and Technology Seoul South Korea Department of Neurology Albert Einstein College of Medicine Bronx USA Center for Neuroscience KIST Seoul South Korea Department of Neuroscience University of Science and Technology Daejon South Korea Systems Neuroscience Group QIMR Berghofer Medical Research Institute Herston Australia Department of Psychology Yonsei University Seoul South Korea Department of Psychiatry Kyung Hee University Hospital at Gangdong Seoul South Korea Department of Psychiatry Veterans Administration Boston Healthcare System and Harvard Medical School Brockton USA Department of Electrical and Electronic Engineering The University of Melbourne Parkvil

A1 Functional advantages of cell-type heterogeneity in neural circuits Tatyana O. Sharpee A2 Mesoscopic modeling of propagating waves in visual cortex Alain Destexhe A3 Dynamics and biomarkers of mental disorders Mitsuo Kawato F1 Precise recruitment of spiking output at theta frequencies requires dendritic h-channels in multi-compartment models of oriens-lacunosum/moleculare hippocampal interneurons Vladislav Sekulić, Frances K. Skinner F2 Kernel methods in reconstruction of current sources from extracellular potentials for single cells and the whole brains Daniel K. Wójcik, Chaitanya Chintaluri, Dorottya Cserpán, Zoltán Somogyvári F3 The synchronized periods depend on intracellular transcriptional repression mechanisms in circadian clocks. Jae Kyoung Kim, Zachary P. Kilpatrick, Matthew R. Bennett, Kresimir Josić O1 Assessing irregularity and coordination of spiking-bursting rhythms in central pattern generators Irene Elices, David Arroyo, Rafael Levi, Francisco B. Rodriguez, Pablo Varona O2 Regulation of top-down processing by cortically-projecting parvalbumin positive neurons in basal forebrain Eunjin Hwang, Bowon Kim, Hio-Been Han, Tae Kim, James T. McKenna, Ritchie E. Brown, Robert W. McCarley, Jee Hyun Choi O3 Modeling auditory stream segregation, build-up and bistability James Rankin, Pamela Osborn Popp, John Rinzel O4 Strong competition between tonotopic neural ensembles explains pitch-related dynamics of auditory cortex evoked fields Alejandro Tabas, André Rupp, Emili Balaguer-Ballester O5 A simple model of retinal response to multi-electrode stimulation Matias I. Maturana, David B. Grayden, Shaun L. Cloherty, Tatiana Kameneva, Michael R. Ibbotson, Hamish Meffin O6 Noise correlations in V4 area correlate with behavioral performance in visual discrimination task Veronika Koren, Timm Lochmann, Valentin Dragoi, Klaus Obermayer O7 Input-location dependent gain modulation in cerebellar nucleus neurons Maria Psarrou, Maria Schilstra, Neil Davey, Benjamin Torben-Ni

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Vortex shedding and heat transfer from a heated circular cylinder in Bingham plastic fluids

arXiv

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arXiv 2024年

作者： Peng, Sai Li, Xiang Yu, Li Zhuang, Xiaoru Yu, Peng School of Mathematics and Computational Science Xiangtan University Xiangtan411105 China Guangdong Provincial Key Laboratory of Turbulence Research and Applications Department of Mechanics and Aerospace Engineering Southern University of Science and Technology Shenzhen518055 China National Center for Applied Mathematics in Hunan Xiangtan411105 China School of Civil Engineering and Architecture Southwest University of Science and Technology Mianyang621010 China Center for Complex Flows and Soft Matter Research Southern University of Science and Technology Shenzhen518055 China School of Mechanical and Electrical Engineering Shenzhen Polytechnic University Shenzhen518055 China

The present study numerically investigates the vortex shedding and heat transfer characteristics of a heated circular cylinder immersed in Bingham plastic fluids. The effects of three parameters, i.e., (i) plastic Reynolds number (10 ≤ Re ≤ 180), (ii) Prandtl number (1 ≤ Pr ≤ 100), and (iii) the Bingham number (0 ≤ Bn ≤ 104), are evaluated. The Navier-Stokes and energy equations for flow and heat transfer are adopted, along with the incorporation of the Papanastasiou regularization to address the discontinuous-viscosity characteristics of Bingham plastic fluids. To illustrate the impact of fluid yield stress on the flow structure, the study provides comprehensive insights into flow transition, streamlines, shear rate and velocity distributions, the morphology of yielded/unyielded regions, and the drag coefficient (Cd). Additionally, the temperature distribution, the local Nusselt number (Nu ̅local ) along the cylinder, and the average Nusselt number on the cylinder (Nu ̅ ) are analyzed. The results indicate that the flow transition of Bingham fluids over a circular cylinder is dependent on external disturbances, exhibiting subcritical bifurcation behavior. This leads to abrupt jumps in the C̅d - Bn curve and the Nu ̅ - Bn curve near the critical Bingham number Bnc. Furthermore, the heat transfer performance is contingent upon the different distribution of shear strain rate in the boundary layer across various Bn ranges. It is observed that Nu ̅ and Bn fits well with the Carreau-Yasuda-like non-Newtonian viscosity model. This investigation enhances the understanding of the vortex shedding and heat transfer behaviors in Bingham plastic fluids. © 2024, CC BY.

关键词： Vortex shedding

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Quality of internal representation shapes learning performance in feedback neural networks

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Physical Review Research 2021年第1期3卷 013176-013176页

作者： Lee Susman Francesca Mastrogiuseppe Naama Brenner Omri Barak Interdisciplinary Program in Applied Mathematics Technion Israel Institute of Technology Haifa 32000 Israel Network Biology Research Laboratories Technion Israel Institute of Technology Haifa 32000 Israel Gatsby Computational Neuroscience Unit University College London London W1T 4JG United Kingdom Department of Chemical Engineering Technion Israel Institute of Technology Haifa 32000 Israel Rappaport Faculty of Medicine Technion Israel Institute of Technology Haifa 32000 Israel

A fundamental feature of complex biological systems is the ability to form feedback interactions with their environment. A prominent model for studying such interactions is reservoir computing, where learning acts on low-dimensional bottlenecks. Despite the simplicity of this learning scheme, the factors contributing to or hindering the success of training in reservoir networks are in general not well understood. In this work, we study nonlinear feedback networks trained to generate a sinusoidal signal, and analyze how learning performance is shaped by the interplay between internal network dynamics and target properties. By performing exact mathematical analysis of linearized networks, we predict that learning performance is maximized when the target is characterized by an optimal, intermediate frequency which monotonically decreases with the strength of the internal reservoir connectivity. At the optimal frequency, the reservoir representation of the target signal is high-dimensional, desynchronized, and thus maximally robust to noise. We show that our predictions successfully capture the qualitative behavior of performance in nonlinear networks. Moreover, we find that the relationship between internal representations and performance can be further exploited in trained nonlinear networks to explain behaviors which do not have a linear counterpart. Our results indicate that a major determinant of learning success is the quality of the internal representation of the target, which in turn is shaped by an interplay between parameters controlling the internal network and those defining the task.

关键词： Learning theory Artificial neural networks Dynamical systems Neuronal network models

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Erratum to “On the dynamics of cranes, or spherical pendula with moving supports” [Int. J. Non-Linear Mech. 37 (2002) 1211]

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International Journal of Non-Linear Mechanics 2003年第2期38卷 285-285页

作者： R.M Ghigliazza P Holmes Department of Mechanical and Aerospace Engineering Princeton University Princeton NJ 08544 USA Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 USA

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