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arXiv 2019年

作者： Sharon, Nir Kileel, Joe Khoo, Yuehaw Landa, Boris Singer, Amit School of Mathematical Sciences Tel Aviv University Israel Program in Applied and Computational Mathematics Princeton University United States Department of Statistics and the College University of Chicago United States Applied Mathematics Program Yale University United States Program in Applied and Computational Mathematics Department of Mathematics Princeton University United States

Single-particle reconstruction in cryo-electron microscopy (cryo-EM) is an increasingly popular technique for determining the 3-D structure of a molecule from several noisy 2-D projections images taken at unknown viewing angles. Most reconstruction algorithms require a low-resolution initialization for the 3-D structure, which is the goal of ab initio modeling. Suggested by Zvi Kam in 1980, the method of moments (MoM) offers one approach, wherein low-order statistics of the 2-D images are computed and a 3-D structure is estimated by solving a system of polynomial equations. Unfortunately, Kam’s method suffers from restrictive assumptions, most notably that viewing angles should be distributed uniformly. Often unrealistic, uniformity entails the computation of higher-order correlations, as in this case first and second moments fail to determine the 3-D structure. In the present paper, we remove this hypothesis, by permitting an unknown, non-uniform distribution of viewing angles in MoM. Perhaps surprisingly, we show that this case is statistically easier than the uniform case, as now first and second moments generically suffice to determine low-resolution expansions of the molecule. In the idealized setting of a known, non-uniform distribution, we find an efficient provable algorithm inverting first and second moments. For unknown, non-uniform distributions, we use non-convex optimization methods to solve for both the molecule and distribution. Copyright © 2019, The Authors. All rights reserved.

关键词： Method of moments

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Preconditioned BFGS-based uncertainty quantification in elastic full waveform inversion

arXiv

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arXiv 2020年

作者： Liu, Qiancheng Beller, Stephen Lei, Wenjie Peter, Daniel Tromp, Jeroen Department of Geosciences Princeton University PrincetonNJ08544 United States Thuwal Saudi Arabia Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States

Full Waveform Inversion (FWI) has become an essential technique for mapping geophysical subsurface structures. However, proper uncertainty quantification is often lacking in current applications. In theory, uncertainty quantification is related to the inverse Hessian (or the posterior covariance matrix). Even for common geophysical inverse problems its calculation is beyond the computational and storage capacities of the largest high-performance computing systems. In this study, we amend the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm to perform uncertainty quantification for large-scale applications. For seismic inverse problems, the limited-memory BFGS (L-BFGS) method prevails as the most efficient quasi-Newton method. We aim to augment it further to obtain an approximate inverse Hessian for uncertainty quantification in FWI. To facilitate retrieval of the inverse Hessian, we combine BFGS (essentially a full-history L-BFGS) with randomized singular value decomposition to determine a low-rank approximation of the inverse Hessian. Setting the rank number equal to the number of iterations makes this solution efficient and memory-affordable even for large-scale problems. Furthermore, based on the Gauss-Newton method, we formulate different initial, diagonal Hessian matrices as preconditioners for the inverse scheme and compare their performances in elastic FWI applications. We highlight our approach with the elastic Marmousi benchmark model, demonstrating the applicability of preconditioned BFGS for large-scale FWI and uncertainty quantification. Copyright © 2020, The Authors. All rights reserved.

关键词： Uncertainty analysis

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Relationship between eddies and SSH in the Indian Ocean during April 2020

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AIP Conference Proceedings 2024年第1期3082卷

作者： M. N. Hidayat R. Wafdan M. Ikhwan M. Ramli Z. A. Muchlisin S. Sugianto M. A. Chaliluddin Samsul Rizal Mathematics Graduate Study Program Universitas Syiah Kuala Banda Aceh 23111 Indonesia Graduate School of Mathematics and Applied Sciences Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Marine Sciences Faculty of Marine and Fisheries Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Mathematics Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Aquaculture Faculty of Marine and Fisheries Universitas Syiah Kuala Banda Aceh 23111 Indonesia Research Center for Marine Sciences and Fisheries Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Soil Sciences Faculty of Agriculture Universitas Syiah Kuala Banda Aceh 23111 Indonesia Department of Fisheries Resource Utilization Faculty of Marine and Fisheries Universitas Syiah Kuala Banda Aceh 23111 Indonesia

Eddies occur almost everywhere in the oceans and play an important role in ocean circulation. They represent a large part of the ocean’s kinetic energy and may indicate their transport and mixing of temperature and salinity. This study investigates the relationship between eddies, sea surface height (SSH), and sea surface temperature (SST) in the Indian Ocean in April 2020. We carry out the analysis using monthly average data for currents, SSH, and SST from the data portal Copernicus Marine Environment Monitoring Service (CMEMS) together with wind data from the National Centers for Environmental Prediction (NCEP) / National Center for Atmospheric Research (NCAR) for April 2020. From the results of this study, we found that two eddies occurred in Aceh waters (coordinates (93°E,5°N) and (98°E,6°N)) in the northern hemisphere. The two Eddies occur with minimal SSH contours in the middle. The direction of the eddies appears in the form of a current counterclockwise movement. Because it occurs in the Northern Hemisphere, the current movement is deflected to the right, resulting in upwelling. The occurrence of a cold SST in the middle of the eddies confirms the appearance of the two eddies.

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TAROGE-M: Antarctic High-Mountain Radio Antenna Array for Detecting Ultra-High Energy ANITA Anomalous Events 38

TAROGE-M: Antarctic High-Mountain Radio Antenna Array for De...

引用

38th International Cosmic Ray Conference, ICRC 2023

作者： Wang, Shih-Hao Chen, Pisin Chen, Yaocheng Chen, Ying-Chih Choi, Taejin Ham, Young-Bae Hsu, Shih-Ying Huang, Jian-Jung Huang, MingHuey A. Jee, Geonhwa Jung, Jongil Kim, Jieun Kuo, Chung-Yun Kwon, Hyuck-Jin Lee, Changsup Leung, Chung-Hei Liu, Tsung-Che Nam, Jiwoo Shiao, Yu-Shao J. Shin, Bok-Kyun Su, Shih-Chieh Wang, Min-Zu Wang, Shih-Hao Wang, Yu-Hsin Anker, Astrid Barwick, Steven W. Besson, Dave Z. Bouma, Sjoerd Cataldo, Maddalena Gaswint, Geoffrey Glaser, Christian Hallmann, Steffen Hanson, Jordan C. Henrichs, Jakob Kleinfelder, Stuart A. Lahmann, Robert Meyers, Zachary S. Nelles, Anna Novikov, Alexander Paul, Manuel P. Pyras, Lilly Persichilli, Christopher Plaisier, Ilse Rice-Smith, Ryan Seikh, Mohammad F. H. Tatar, Joulien Welling, Christoph Zhao, Leshan Department of Physics National Taiwan University Taipei10617 Taiwan Leung Center for Cosmology and Particle Astrophysics National Taiwan University Taipei10617 Taiwan Kavli Institute for Particle Astrophysics and Cosmology SLAC National Accelerator Laboratory Stanford University StanfordCA94305 United States Division of Atmospheric Sciences Korea Polar Research Institute Incheon Korea Republic of Department of Polar Science Korea University of Science and Technology Daejeon Korea Republic of Department of Energy Engineering National United University Miaoli Taiwan Department of Astronomy Space Science and Geology Chungnam National University Daejeon34134 Korea Republic of Department of Physics and Astronomy University of Delaware NewarkDE19716 United States Department of Electrophysics National Yang Ming Chiao Tung University Hsinchu300 Taiwan Department of applied physics National Pingtung university Pingtung900 Taiwan Chung Cheng Institute of Technology National Defense University Taoyuan335 Taiwan Undergraduate Degree Program of Systems Engineering and Technology National Yang Ming Chiao Tung University Hsinchu300 Taiwan National Nano Device Laboratories Hsinchu300 Taiwan Ulsan National Institute of Science and Technology Ulsan44919 Korea Republic of Institute of Astronomy and Astrophysics Academia Sinica Astronomy-Mathematics Building No. 1 Sec. 4 Roosevelt Rd. Taipei10617 Taiwan Department of Physics and Astronomy University of California IrvineCA92697 United States Department of Physics and Astronomy University of Kansas LawrenceKS66045 United States DESY Zeuthen15738 Germany ECAP Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen91058 Germany Uppsala University Department of Physics and Astronomy UppsalaSE-752 37 Sweden Whittier College Department of Physics WhittierCA90602 United States Department of Electrical Engineering and Computer Science University of California IrvineCA92697 United States Resea

TAROGE-M is a radio antenna array atop ∼ 2.7 km-high Mt. Melbourne in Antarctica for detecting ultra-high energy (UHE, E > 1017 eV) air showers in near-horizontal directions. Besides the detection of cosmic rays and Earth-skimming tau neutrinos, its primary goal is to reproduce the discovery and verify the origin of so-called ANITA anomalous events, having feature of upward-going UHE air showers but cannot be explained by tau neutrinos. The detection concept takes advantages of a high altitude for a broad view toward the horizon;strong and near-vertical geomagnetic field for enhancing the radio signal;and quiet radio environment in Antarctica. Its relatively simple design and high duty cycle make it easily to be extended and thus to achieve an exposure competitive with ANITA experiments within a few years. The first TAROGE-M station operating at 180-450 MHz frequencies deployed in 2020 detected seven UHE cosmic ray events within 25.3-day livetime. The events have a mean energy of ∼ 1 EeV and an estimated flux consistent with other experiments, and validate the station as an UHE particle detector. In 2022-2023 season, the system was upgraded for a robust long-term operation, with a more detailed calibration with a drone-borne pulser. We also discuss the planned upgrade, including the implementation of interferometric trigger, which is expected to increase the cosmic ray and tau neutrino acceptances by a factor of 10 at 0.1 EeV, corresponding to a lower energy threshold by a factor of 3. © Copyright owned by the author(s) under the terms of the Creative Commons.

关键词： Cosmic rays

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Bayesian Testing Of Granger Causality In Functional Time Series

arXiv

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arXiv 2021年

作者： Sen, Rituparna Majumdar, Anandamayee Sikaria, Shubhangi Applied Statistics Unit Indian Statistical Institute 8th Mile Mysore Rd RVCE Post KA Bangalore560059 India Stock Assessment Program Inter-American Tropical Tuna Commission San DiegoCA United States Department of Mathematics Indian Institute of Technology Madras TN Chennai India

We develop a multivariate functional autoregressive model (MFAR), which captures the cross-correlation among multiple functional time series and thus improves forecast accuracy. We estimate the parameters under the Bayesian dynamic linear models (DLM) framework. In order to capture Granger causality from one FAR series to another we employ Bayes Factor. Motivated by the broad application of functional data in finance, we investigate the causality between the yield curves of two countries. Furthermore, we illustrate a climatology example, examining whether the weather conditions Granger cause pollutant daily levels in a city. Copyright © 2021, The Authors. All rights reserved.

关键词： Statistical tests

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The SL(2, Z) dualization algorithm at work

arXiv

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arXiv 2022年

作者： Comi, Riccardo Hwang, Chiung Marino, Fabio Pasquetti, Sara Sacchi, Matteo Dipartimento di Fisica Università di Milano-Bicocca Piazza della Scienza 3 MilanoI-20126 Italy INFN Sezione di Milano-Bicocca Piazza della Scienza 3 MilanoI-20126 Italy Interdisciplinary Center for Theoretical Study University of Science and Technology of China Anhui Hefei230026 China Peng Huanwu Center for Fundamental Theory Anhui Hefei230026 China Daejeon34126 Korea Republic of Department of Applied Mathematics and Theoretical Physics University of Cambridge CambridgeCB3 0WA United Kingdom Department of Mathematics University of Surrey GuildfordGU2 7XH United Kingdom Mathematical Institute University of Oxford Woodstock Road OxfordOX2 6GG United Kingdom

Recently an algorithm to dualize a theory into its mirror dual has been proposed, both for 3d N = 4 linear quivers and for their 4d N = 1 uplift. This mimics the manipulations done at the level of the Type IIB brane setup that engineers the 3d theories, where mirror symmetry is realized as S-duality, but it is enirely field-theoretic and based on the application of genuine infra-red dualities that implement the local action of S-duality on the quiver. In this paper, we generalize the algorithm to the full duality group, which is SL(2,Z) in 3d and PSL(2,Z) in 4d. This also produces dualities for 3d N = 3 theories with Chern–Simons couplings, some of which have enhanced N = 4 supersymmetry, and their new 4d N = 1 counterpart. In addition, we propose three ways to study the RG flows triggered by possible VEVs appearing at the last step of the algorithm, one of which uses a new duality that implements the Hanany–Witten move in field theory. Copyright © 2022, The Authors. All rights reserved.

关键词： Mirrors

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引用

Journal of Allergy and Clinical Immunology: Global 2024年第4期3卷 100326-100326页

作者： Herrmann, Susan Kulkarni, Rishabh Trevenen, Michelle Karuppasamy, Hana Willis, Catherine Berry, Renee Von Ungern-Sternberg, Britta Warrier, Niklesh Li, Ian Murray, Kevin Lucas, Michaela School of Medicine The University of Western Australia Perth Australia Department of Immunology Sir Charles Gairdner Hospital Perth Australia Centre for Applied Statistics School of Physics Mathematics and Computing The University of Western Australia Perth Australia Department of Immunology Fiona Stanley Hospital Perth Australia Department of Anaesthesia and Pain Medicine Perth Children's Hospital Perth Australia Division of Emergency Medicine Anaesthesia and Pain Medicine Medical School The University of Western Australia Perth Australia Institute for Paediatric Perioperative Excellence The University of Western Australia Perth Australia Perioperative Medicine Team Perioperative Care Program Telethon Kids Institute Perth Australia National Centre for Student Equity in Higher Education Curtin University Perth Australia School of Population Health The University of Western Australia Perth Australia

Background: The clinical consequences of an antibiotic allergy label are detrimental, impacting health care delivery and patient outcomes. We assessed hospital inpatients with intent to offer free antibiotic allergy labeling (AAL) assessment within a randomized controlled trial. Objective: We sought to determine the feasibility of establishing an adult antibiotic allergy delabeling service in a Western Australian tertiary public hospital. Methods: Inpatients (N = 1503) with AAL were identified through medical records and screened for eligibility to participate in a randomized controlled trial. Those recruited were randomized to undergo assessment by skin testing ± oral challenge, or direct oral challenge. A control group received usual care. Results: Of the 1503 inpatients with an AAL, 429 (28.5%) were eligible for AAL assessment. The primary excluding factor (1074 [71.5%]) was contraindicated medication use (387 [36.0%]), followed by cognitive impairment (298 [27.9%]). Thirty-nine patients were randomized, of which 20 received allergy testing and 19 usual care;all patients were followed up for 5 years. Older patients were less likely to be eligible (10-year increase: odds ratio, 0.82;95% CI, 0.77-0.88;P < .0001), whereas surgical patients were more likely to be eligible than medical patients (odds ratio, 2.49;95% CI, 1.97-3.16;P < .0001). Conclusions: Antibiotic allergy delabeling in the acute care context is not straightforward. Competing clinical concerns and patient acceptance are some barriers to an inpatient service. Nor is it apparent that inpatient versus outpatient testing is cost saving although select patient groups may benefit. Testing younger people and those with predicted high antibiotic usage will derive maximal individual and health system benefits. © 2024 The Authors

关键词： adult inpatients Antibiotic allergy delabeling drug allergy

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Multilevel quasi-Monte Carlo for random elliptic eigenvalue problems I: Regularity and error analysis

arXiv

引用

arXiv 2020年

作者： Gilbert, Alexander D. Scheichl, Robert School of Mathematics and Statistics University of New South Wales SydneyNSW2052 Australia Institute for Applied Mathematics Interdisciplinary Centre for Scientific Computing Universität Heidelberg Heidelberg69120 Germany Department of Mathematical Sciences University of Bath BathBA2 7AY United Kingdom

Stochastic PDE eigenvalue problems are useful models for quantifying the uncertainty in several applications from the physical sciences and engineering, e.g., structural vibration analysis, the criticality of a nuclear reactor or photonic crystal structures. In this paper we present a multilevel quasi-Monte Carlo (MLQMC) method for approximating the expectation of the minimal eigenvalue of an elliptic eigenvalue problem with coefficients that are given as a series expansion of countably-many stochastic parameters. The MLQMC algorithm is based on a hierarchy of discretisations of the spatial domain and truncations of the dimension of the stochastic parameter domain. To approximate the expectations, randomly shifted lattice rules are employed. This paper is primarily dedicated to giving a rigorous analysis of the error of this algorithm. A key step in the error analysis requires bounds on the mixed derivatives of the eigenfunction with respect to both the stochastic and spatial variables simultaneously. Under stronger smoothness assumptions on the parametric dependence, our analysis also extends to multilevel higher-order quasi-Monte Carlo rules. An accompanying paper [Gilbert and Scheichl, 2022], focusses on practical extensions of the MLQMC algorithm to improve efficiency, and presents numerical results. Copyright © 2020, The Authors. All rights reserved.

关键词： Error analysis

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Deep Potential generation scheme and simulation protocol for the Li10GeP2S12-type superionic conductors

arXiv

引用

arXiv 2020年

作者： Huang, Jianxing Zhang, Linfeng Wang, Han Zhao, Jinbao Cheng, Jun Weinan, E. State Key Laboratory of Physical Chemistry of Solid Surfaces iChEM College of Chemistry and Chemical Engineering Xiamen University Xiamen361005 China Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Fenghao East Road 2 Beijing100094 China Department of Mathematics Princeton University PrincetonNJ08544 United States

Solid-state electrolyte materials with superior lithium ionic conductivities are vital to the next-generation Li-ion batteries. Molecular dynamics could provide atomic scale information to understand the diffusion process of Li-ion in these superionic conductor materials. Here we implement the Deep Potential Generator (DP-GEN) to set up an efficient protocol to automatically generate interatomic potentials for Li10GeP2S12-type solid-state electrolyte materials (Li10GeP2S12, Li10SiP2S12 and Li10SnP2S12). The reliability and accuracy of the fast interatomic potentials are validated. With the potentials, we extend the simulation of diffusion process to a wide temperature range (300K-1000K) and systems with large size (~1000 atoms). Important technical aspects like the statistical error and size effect are carefully investigated and benchmark tests including the effect of density functional, thermal expansion and configurational disorder are performed. The computed data that considering these factors agrees well with the experimental results and we find that the 3 structures shows different behaviors with respect to configurational disorder. Our work paves the way for further research on computation screening of solid-state electrolyte materials. Copyright © 2020, The Authors. All rights reserved.

关键词： Solid electrolytes

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A Priori Estimates of the Population Risk for Residual Networks

arXiv

引用

arXiv 2019年

作者： Weinan, E. Ma, Chao Wang, Qingcan Department of Mathematics Princeton University Program in Applied and Computational Mathematics Princeton University Beijing Institute of Big Data Research

Optimal a priori estimates are derived for the population risk, also known as the generalization error, of a regularized residual network model. An important part of the regularized model is the usage of a new path norm, called the weighted path norm, as the regularization term. The weighted path norm treats the skip connections and the nonlinearities differently so that paths with more nonlinearities are regularized by larger weights. The error estimates are a priori in the sense that the estimates depend only on the target function, not on the parameters obtained in the training process. The estimates are optimal, in a high dimensional setting, in the sense that both the bound for the approximation and estimation errors are comparable to the Monte Carlo error rates. A crucial step in the proof is to establish an optimal bound for the Rademacher complexity of the residual networks. Comparisons are made with existing norm-based generalization error bounds. Copyright © 2019, The Authors. All rights reserved.

关键词： Error analysis

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