数学最新文献 - Book学术

Morse Predecomposition of an Invariant Set. 不变集的莫尔斯预分解。

IF 1.9 3区数学

Qualitative Theory of Dynamical Systems Pub Date : 2025-01-01 Epub Date: 2024-11-15 DOI: 10.1007/s12346-024-01144-3

Michał Lipiński, Konstantin Mischaikow, Marian Mrozek

引用次数: 0

Functional Concurrent Regression Mixture Models Using Spiked Ewens-Pitman Attraction Priors. 使用尖刺Ewens-Pitman吸引先验的功能并发回归混合模型

IF 4.9 3区材料科学

ACS Applied Energy Materials Pub Date : 2024-12-01 Epub Date: 2023-05-02 DOI: 10.1214/23-ba1380

Mingrui Liang, Matthew D Koslovsky, Emily T Hébert, Michael S Businelle, Marina Vannucci

{"title":"Functional Concurrent Regression Mixture Models Using Spiked Ewens-Pitman Attraction Priors.","authors":"Mingrui Liang, Matthew D Koslovsky, Emily T Hébert, Michael S Businelle, Marina Vannucci","doi":"10.1214/23-ba1380","DOIUrl":"10.1214/23-ba1380","url":null,"abstract":"<p><p>Functional concurrent, or varying-coefficient, regression models are a form of functional data analysis methods in which functional covariates and outcomes are collected concurrently. Two active areas of research for this class of models are identifying influential functional covariates and clustering their relations across observations. In various applications, researchers have applied and developed methods to address these objectives separately. However, no approach currently performs both tasks simultaneously. In this paper, we propose a fully Bayesian functional concurrent regression mixture model that simultaneously performs functional variable selection and clustering for subject-specific trajectories. Our approach introduces a novel spiked Ewens-Pitman attraction prior that identifies and clusters subjects' trajectories marginally for each functional covariate while using similarities in subjects' auxiliary covariate patterns to inform clustering allocation. Using simulated data, we evaluate the clustering, variable selection, and parameter estimation performance of our approach and compare its performance with alternative spiked processes. We then apply our method to functional data collected in a novel, smartphone-based smoking cessation intervention study to investigate individual-level dynamic relations between smoking behaviors and potential risk factors.</p>","PeriodicalId":4,"journal":{"name":"ACS Applied Energy Materials","volume":" ","pages":"1067-1095"},"PeriodicalIF":4.9,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11507269/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43506288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Recoverability of causal effects under presence of missing data: a longitudinal case study. 数据缺失情况下因果效应的可恢复性：纵向案例研究。

IF 1.8 3区数学

Biostatistics Pub Date : 2024-11-18 DOI: 10.1093/biostatistics/kxae044

Anastasiia Holovchak, Helen McIlleron, Paolo Denti, Michael Schomaker

{"title":"Recoverability of causal effects under presence of missing data: a longitudinal case study.","authors":"Anastasiia Holovchak, Helen McIlleron, Paolo Denti, Michael Schomaker","doi":"10.1093/biostatistics/kxae044","DOIUrl":"https://doi.org/10.1093/biostatistics/kxae044","url":null,"abstract":"<p><p>Missing data in multiple variables is a common issue. We investigate the applicability of the framework of graphical models for handling missing data to a complex longitudinal pharmacological study of children with HIV treated with an efavirenz-based regimen as part of the CHAPAS-3 trial. Specifically, we examine whether the causal effects of interest, defined through static interventions on multiple continuous variables, can be recovered (estimated consistently) from the available data only. So far, no general algorithms are available to decide on recoverability, and decisions have to be made on a case-by-case basis. We emphasize the sensitivity of recoverability to even the smallest changes in the graph structure, and present recoverability results for three plausible missingness-directed acyclic graphs (m-DAGs) in the CHAPAS-3 study, informed by clinical knowledge. Furthermore, we propose the concept of a \"closed missingness mechanism\": if missing data are generated based on this mechanism, an available case analysis is admissible for consistent estimation of any statistical or causal estimand, even if data are missing not at random. Both simulations and theoretical considerations demonstrate how, in the assumed MNAR setting of our study, a complete or available case analysis can be superior to multiple imputation, and estimation results vary depending on the assumed missingness DAG. Our analyses demonstrate an innovative application of missingness DAGs to complex longitudinal real-world data, while highlighting the sensitivity of the results with respect to the assumed causal model.</p>","PeriodicalId":55357,"journal":{"name":"Biostatistics","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142649856","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Helmholtz FEM solutions are locally quasi-optimal modulo low frequencies 亥姆霍兹有限元求解在低频局部准最优

IF 1.7 3区数学

Advances in Computational Mathematics Pub Date : 2024-11-18 DOI: 10.1007/s10444-024-10193-w

M. Averseng, J. Galkowski, E. A. Spence

{"title":"Helmholtz FEM solutions are locally quasi-optimal modulo low frequencies","authors":"M. Averseng, J. Galkowski, E. A. Spence","doi":"10.1007/s10444-024-10193-w","DOIUrl":"10.1007/s10444-024-10193-w","url":null,"abstract":"<div><p>For <i>h</i>-FEM discretisations of the Helmholtz equation with wavenumber <i>k</i>, we obtain <i>k</i>-explicit analogues of the classic local FEM error bounds of Nitsche and Schatz (Math. Comput. <b>28</b>(128), 937–958 1974), Wahlbin (1991, §9), Demlow et al.(Math. Comput. <b>80</b>(273), 1–9 2011), showing that these bounds hold with constants independent of <i>k</i>, provided one works in Sobolev norms weighted with <i>k</i> in the natural way. We prove two main results: (i) a bound on the local <span>(H^1)</span> error by the best approximation error plus the <span>(L^2)</span> error, both on a slightly larger set, and (ii) the bound in (i) but now with the <span>(L^2)</span> error replaced by the error in a negative Sobolev norm. The result (i) is valid for shape-regular triangulations, and is the <i>k</i>-explicit analogue of the main result of Demlow et al. (Math. Comput. <b>80</b>(273), 1–9 2011). The result (ii) is valid when the mesh is locally quasi-uniform on the scale of the wavelength (i.e., on the scale of <span>(k^{-1})</span>) and is the <i>k</i>-explicit analogue of the results of Nitsche and Schatz (Math. Comput. <b>28</b>(128), 937–958 1974), Wahlbin (1991, §9). Since our Sobolev spaces are weighted with <i>k</i> in the natural way, the result (ii) indicates that the Helmholtz FEM solution is locally quasi-optimal modulo low frequencies (i.e., frequencies <span>(lesssim k)</span>). Numerical experiments confirm this property, and also highlight interesting propagation phenomena in the Helmholtz FEM error.</p></div>","PeriodicalId":50869,"journal":{"name":"Advances in Computational Mathematics","volume":"50 6","pages":""},"PeriodicalIF":1.7,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10444-024-10193-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Is (Independent) Subordination Relevant in Equity Derivatives? 独立）从属关系与股票衍生品相关吗？

IF 1.4 4区数学

Applied Stochastic Models in Business and Industry Pub Date : 2024-11-18 DOI: 10.1002/asmb.2904

Michele Azzone, Roberto Baviera

引用次数: 0

Global Attractor and Singular Limits of the 3D Voigt-regularized Magnetohydrodynamic Equations 三维 Voigt 规则化磁流体动力学方程的全局吸引和奇异极限

IF 1.2 3区数学

Journal of Mathematical Fluid Mechanics Pub Date : 2024-11-18 DOI: 10.1007/s00021-024-00909-9

Xuesi Kong, Xingjie Yan, Rong Yang

引用次数: 0

Nonparametric estimation of the cumulative incidence function for doubly-truncated and interval-censored competing risks data. 双截断和区间截断竞争风险数据的累积发病率函数的非参数估计。

IF 1.2 3区数学

Lifetime Data Analysis Pub Date : 2024-11-17 DOI: 10.1007/s10985-024-09641-y

Pao-Sheng Shen

引用次数: 0

Chow–Witt rings and topology of flag varieties 周维特环和旗变拓扑学

IF 0.8 2区数学

Journal of Topology Pub Date : 2024-11-17 DOI: 10.1112/topo.70004

Thomas Hudson, Ákos K. Matszangosz, Matthias Wendt

引用次数: 0

Propagation dynamics of the second-order chirped circular Pearcey Gaussian vortex beam in the fractional nonlinear Schrödinger equation 分数非线性薛定谔方程中二阶啁啾圆皮尔斯高斯涡旋束的传播动力学

IF 5.3 1区数学

Chaos Solitons & Fractals Pub Date : 2024-11-16 DOI: 10.1016/j.chaos.2024.115734

Shangling He , Xi Peng , Yingji He , Chun Shan , Dongmei Deng

{"title":"Propagation dynamics of the second-order chirped circular Pearcey Gaussian vortex beam in the fractional nonlinear Schrödinger equation","authors":"Shangling He , Xi Peng , Yingji He , Chun Shan , Dongmei Deng","doi":"10.1016/j.chaos.2024.115734","DOIUrl":"10.1016/j.chaos.2024.115734","url":null,"abstract":"<div><div>We present the propagation dynamics of the second-order chirped circular Pearcey Gaussian vortex beam (CCPGVB) in the Fractional nonlinear Schrödinger equation (FNSE) numerically and find some interesting behaviors. The CCPGVB can propagate like quasi solitons along the propagation direction. The autofocusing effect of the CCPGVB gets stronger while the autofocusing length monotonously decreases and the number of focus become lessen as the Lévy index approaches 2. By adjusting the Lévy index, the chirp factor <span><math><mi>β</mi></math></span>, the input power <span><math><msub><mrow><mi>P</mi></mrow><mrow><mi>i</mi><mi>n</mi></mrow></msub></math></span>, as well as the order of the off-axis vortex pair <span><math><mrow><mo>(</mo><mi>m</mi><mo>,</mo><mi>l</mi><mo>)</mo></mrow></math></span>, the results show that these factors can effectively control the propagation dynamics of the CCPGVB, including intensity distribution, focal length, focal intensity, the light spot and the number of focus. Finally, the Poynting vector and the angular momentum of the CCPGVB prove the autofocusing and diffraction behaviors.</div></div>","PeriodicalId":9764,"journal":{"name":"Chaos Solitons & Fractals","volume":"189 ","pages":"Article 115734"},"PeriodicalIF":5.3,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142650738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Activation energy and non-Darcy effects on magnetized Jeffery-Hamel (JH) flow in convergent/divergent channels 收敛/发散通道中磁化杰弗里-哈梅尔（JH）流的活化能和非达西效应

IF 5.3 1区数学

Chaos Solitons & Fractals Pub Date : 2024-11-16 DOI: 10.1016/j.chaos.2024.115749

Subhan Ullah , Amir Ali , Ikram Ullah , Mohammad Mahtab Alam , Zareen A. Khan

{"title":"Activation energy and non-Darcy effects on magnetized Jeffery-Hamel (JH) flow in convergent/divergent channels","authors":"Subhan Ullah , Amir Ali , Ikram Ullah , Mohammad Mahtab Alam , Zareen A. Khan","doi":"10.1016/j.chaos.2024.115749","DOIUrl":"10.1016/j.chaos.2024.115749","url":null,"abstract":"<div><div>Nanofluids have gained significant attention for enhancing heat and mass transfer, particularly in complex flow configurations like convergent and divergent channels. Key applications include improved solar collectors, cooling in heat exchangers, nuclear reactors, drug delivery, thermoelectric systems, reduced friction in lubrication and thermal therapies. In this context, the present research examines the impact of Darcy-Forchheimer aspect on Jeffery-Hamel nanofluids flow through non-parallel converging/diverging channels. The behavior of nanoparticles is exhibited and investigated through the Buongiorno model for nanomaterials. Enhancing thermal efficiency is crucial for many fluids, and this study aims to explore its significance. As the increment in thermal efficiency of many fluids can be more important. The influence of Soret Dufour aspects, heat source, and activation energy are also come upon in current study. Lorentz force, solar radiation and thermal radiations are further examine arises due to the magnetic field application. The current main system of differential equations is converted into ordinary differential equations by appropriate transformations. The obtained systems of are numerically simulated with the help of Mathematica-9 software utilizing the NDSolve technique. The consequences of various physical factors on subjective distributions and engineering quantities are examined. In addition, validation of numerical technique also provided.</div></div>","PeriodicalId":9764,"journal":{"name":"Chaos Solitons & Fractals","volume":"189 ","pages":"Article 115749"},"PeriodicalIF":5.3,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142650724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0