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Unified calculation of generalized oscillator strength of argon ranging from bound to continuum states

Physical Review A 2015年第5期92卷 052712-052712页

作者： Xiang Gao Rui Jin De-Ling Zeng Xiao-Ying Han Jun Yan Jia-Ming Li Beijing Computational Science Research Center Beijing 100094 China Department of Physics and Center for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

The electron and photon scattering data of an atom are crucial for many scientific fields, including plasma physics, astrophysics, and so on. For high enough but nonrelativistic incident energies, the first Born approximation is applicable for calculating these data, in which the key physics quantity is the generalized oscillator strength (GOS). In high-energy electron impact excitation processes, atoms will be excited into various excited states including strongly perturbed Rydberg and adjacent continuum states. How to calculate these quantities of a nontrivial many-electron atom rapidly and accurately is still a great challenge. Based on our eigenchannel R-matrix method R-eigen, we further extend it to calculate the GOS of a whole channel in an atom, which includes all Rydberg and adjacent continuum states. The Jπ=1− states of argon are chosen as an illustrating example. The calculation results are in good agreement with the available benchmark absolute experimental measurements. The calculated eigenchannel GOS matrix elements are smooth functions of the excitation energy and momentum transfer. From such smooth eigenchannel GOS matrix elements, we can obtain the GOS of any specific excited state through multichannel quantum defect theory, e.g., infinite Rydberg (including a strongly perturbed one), autoionization, and continuum states.

关键词： ELECTRON scattering RESEARCH PHOTON scattering AUGER effect QUANTUM defect theory RYDBERG states

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Multi-patch and multi-group epidemic models: A new framework

arXiv

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arXiv 2017年

作者： Bichara, Derdei Iggidr, Abderrahman Department of Mathematics Center for Computational and Applied Mathematics California State University FullertonCA92831 United States Inria Université de Lorraine CNRS Institut Elie Cartan de Lorraine UMR 7502 ISGMP Bat. A Ile du Saulcy Metz Cedex 0157045 France

We develop a multi-patch and multi-group model that captures the dynamics of an infectious disease when the host is structured into an arbitrary number of groups and interacts into an arbitrary number of patches where the infection takes place. In this framework, we model host mobility that depends on its epidemiological status, by a Lagrangian approach. This framework is applied to a general SEIRS model and the basic reproduction number R0 is derived. The effects of heterogeneity in groups, patches and mobility patterns on R0 and disease prevalence are explored. Our results show that for a fixed number of groups, the basic reproduction number increases with respect to the number of patches and the host mobility patterns. Moreover, when the mobility matrix of susceptible individuals is of rank one, the basic reproduction number is explicitly determined and was found to be independent of the latter if the matrix is also stochastic. The cases where mobility matrices are of rank one capture important modeling scenarios. Additionally, we study the global analysis of equilibria for some special cases. Numerical simulations are carried out to showcase the ramifications of mobility pattern matrices on disease prevalence and basic reproduction *** Codes 92D25, 92D30 Copyright © 2017, The Authors. All rights reserved.

关键词： Stochastic systems

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Flexible categorization using formal concept analysis and Dempster-Shafer theory

arXiv

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arXiv 2024年

作者： Boersma, Marcel Manoorkar, Krishna Palmigiano, Alessandra Panettiere, Mattia Tzimoulis, Apostolos Wijnberg, Nachoem School of Business and Economics Vrije Universiteit Amsterdam Netherlands Department of Mathematics and Applied Mathematics University of Johannesburg South Africa College of Business and Economics University of Johannesburg South Africa Faculty of Economics and Business University of Amsterdam Netherlands Computational Science Lab University of Amsterdam Amsterdam Netherlands KPMG Amstelveen Netherlands

The framework developed in the present paper provides a formal ground to generate and study explainable categorizations of sets of entities, based on the epistemic attitudes of individual agents or groups thereof. Based on this framework, we discuss a machine-leaning meta-algorithm for outlier detection and classification which provides local and global explanations of its results. © 2024, CC BY.

关键词： Formal concept analysis

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FLCSFD - A fuzzy local-based approach for detecting cerebrospinal fluid regions in presence of MS lesions

FLCSFD - A fuzzy local-based approach for detecting cerebros...

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IEEE/ICME International Conference on Complex Medical Engineering, CME

作者： F. X. Aymerich E. Montseny P. Sobrevilla A. Rovira Computational Engineering and Industrial Systems Department Technical University of Catalonia Barcelona Spain Applied Mathematics II Department Technical University of Catalonia Barcelona Spain Magnetic Resonance Unit-IDI Vall Hebron University Hospital Barcelona Spain

Magnetic Resonance Imaging (MRI) is an important paraclinical tool for diagnosing Multiple Sclerosis (MS) and providing several markers of disease activity and evolution. Traditionally, hypointense lesions on Tl-weighted images have been reported to represent areas where demyelination and axonal loss have occurred, and are the images usually selected for segmenting the encephalic parenchyma. Based on the fact that in Tl-weighted images MS lesions cannot be located within cerebrospinal fluid regions (CSF), a correct detection of such regions is very useful to filter MS's false detections. However, the gray levels similarity among some MS lesions and CDF regions makes of the encephalic parenchyma detection process a difficult task. In this work we propose an approach for detecting CSF regions in which, for taking into consideration aforementioned gray-level vagueness, as well as the intrinsic uncertainty of CSF boundaries, we make use of fuzzy techniques. The proposed algorithm performs a fuzzy local analysis based on gray-level and texture characteristics, but considering the location and size of the CSF regions. As a result, the algorithm allows discriminating cerebrospinal fluid regions inside the intracranial region, providing confidence degrees that match with the possibility of including pixels associated to MS lesion.

关键词： Lesions Multiple sclerosis Magnetic resonance imaging Image segmentation Image analysis Algorithm design and analysis Diseases Uncertainty Performance analysis Central nervous system

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Causes of evolutionary divergence in prostate cancer

arXiv

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arXiv 2025年

作者： Esentürk, Emre Sahli, Atef Haberland, Valeriia Ziuboniewicz, Aleksandra Wirth, Christopher Bova, G. Steven Bristow, Robert G. Brook, Mark N. Brors, Benedikt Butler, Adam Cancel-Tassin, Géraldine Cheng, Kevin C.L. Cooper, Colin S. Corcoran, Niall M. Cussenot, Olivier Eeles, Ros A. Favero, Francesco Gerhauser, Clarissa Gihawi, Abraham Girma, Etsehiwot G. Gnanapragasam, Vincent J. Gruber, Andreas J. Hamid, Anis Hayes, Vanessa M. He, Housheng Hansen Hovens, Christopher M. Imada, Eddie Luidy Jakobsdottir, G. Maria Jung, Chol-Hee Khani, Francesca Kote-Jarai, Zsofia Lamy, Philippe Leeman, Gregory Loda, Massimo Lutsik, Pavlo Marchionni, Luigi Molania, Ramyar Papenfuss, Anthony T. Pellegrina, Diogo Pope, Bernard Queiroz, Lucio R. Rausch, Tobias Reimand, Jüri Robinson, Brian Schlomm, Thorsten Sørensen, Karina D. Uhrig, Sebastian Weischenfeldt, Joachim Xu, Yaobo Yamaguchi, Takafumi N. Zanettini, Claudio Lynch, Andy G. Wedge, David C. Brewer, Daniel S. Woodcock, Dan J. Nuffield Department of Medicine University of Oxford United Kingdom Manchester Cancer Research Centre The University of Manchester United Kingdom Norwich Medical School University of East Anglia United Kingdom Nuffield Department of Surgical Sciences University of Oxford United Kingdom Prostate Cancer Research Center Faculty of Medicine and Health Technology Tampere University Finland Manchester Cancer Research Centre Cancer Research UK Manchester Institute The University of Manchester United Kingdom Christie NHS Foundation Trust United Kingdom Div Cancer Sciences Faculty of Biology Medicine & Health University of Manchester United Kingdom The Institute of Cancer Research United Kingdom Germany Germany Medical Faculty Heidelberg Faculty of Biosciences Heidelberg University Germany Wellcome Sanger Institute United Kingdom France Sorbonne Université GRC n°5 Predictive Onco-Urology APHP Tenon Hospital France Computational Biology Program Ontario Institute for Cancer Research Canada Department of Medical Biophysics University of Toronto Canada Department of Urology Royal Melbourne Hospital Australia Department of Surgery The University of Melbourne Australia Department of Urology Western Health Australia The Royal Marsden NHS Foundation Trust London United Kingdom University of Copenhagen Denmark Finsen Laboratory Copenhagen University Hospital - Rigshospitalet Denmark Germany Cambridge Biomedical Campus Addenbrooke's Hospital Site S Wards Building United Kingdom University of Konstanz Germany School of Medical Sciences University of Sydney Faculty of Medicine & Health Australia School of Health Systems & Public Health University of Pretoria South Africa Manchester Cancer Research Centre University of Manchester United Kingdom Princess Margaret Cancer Centre University Health Network Department of Medical Biophysics University of Toronto Canada Department of Surgery The Collaborative Centre for Genomic Cancer Medicine The University of Melbourne

Cancer progression involves the sequential accumulation of genetic alterations that cumulatively shape the tumour phenotype. In prostate cancer, tumours can follow divergent evolutionary trajectories that lead to distinct subtypes, but the causes of this divergence remain unclear. While causal inference could elucidate the factors involved, conventional methods are unsuitable due to the possibility of unobserved confounders and ambiguity in the direction of causality. Here, we propose a method that circumvents these issues and apply it to genomic data from 829 prostate cancer patients. We identify several genetic alterations that drive divergence as well as others that prevent this transition, locking tumours into one trajectory. Further analysis reveals that these genetic alterations may cause each other, implying a positive-feedback loop that accelerates divergence. Our findings provide insights into how cancer subtypes emerge and offer a foundation for genomic surveillance strategies aimed at monitoring the progression of prostate cancer. © 2025, CC BY-NC-SA.

关键词： Lung cancer

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UNBIASED INFERENCE for DISCRETELY OBSERVED HIDDEN MARKOV MODEL DIFFUSIONS

arXiv

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arXiv 2018年

作者： Chada, Neil K. Franks, Jordan Jasra, Ajay Law, Kody J.H. Vihola, Matti Applied Mathematics and Computational Science King Abdullah University of Science and Technology Thuwal23955 Saudi Arabia School of Mathematics Statistics and Physics Herschel Building NE1 7RU Newcastle University United Kingdom Department of Mathematics and Statistics University of Jyväskylä P.O.Box 35 FIFI-40014 Finland School of Mathematics University of Manchester ManchesterM13 9PL United Kingdom

We develop a Bayesian inference method for diffusions observed discretely and with noise, which is free of discretisation bias. Unlike existing unbiased inference methods, our method does not rely on exact simulation techniques. Instead, our method uses standard time-discretised approximations of diffusions, such as the Euler-Maruyama scheme. Our approach is based on particle marginal Metropolis-Hastings, a particle filter, randomised multilevel Monte Carlo, and importance sampling type correction of approximate Markov chain Monte Carlo. The resulting estimator leads to inference without a bias from the time-discretisation as the number of Markov chain iterations increases. We give convergence results and recommend allocations for algorithm inputs. Our method admits a straightforward parallelisation, and can be computationally efficient. The user-friendly approach is illustrated on three examples, where the underlying diffusion is an Ornstein-Uhlenbeck process, a geometric Brownian motion, and a 2d non-reversible Langevin *** Codes 65C05 (primary), 60H35, 65C35, 65C40 (secondary) Copyright © 2018, The Authors. All rights reserved.

关键词： Diffusion

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Scaling law for transition probabilities in 2p3 configuration from LS coupling to jj coupling

引用

Physical Review A 2014年第4期89卷 042514-042514页

作者： Xiao-Ying Han Xiang Gao De-lin Zeng Rui Jin Jun Yan Jia-Ming Li Institute of Applied Physics and Computational Mathematics Beijing 100088 China Beijing Computational Science Research Center Beijing 100084 China Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Department of Physics and Center for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

The E2 and M1 transition rates among the lowest five states ([4S3/2o]′,[2D5/2o]′,[2D3/2o]′,[2P3/2o]′,[2P1/2o]′), i.e., the [2D5/2,3/2o]′→[4S3/2o]′ and [2P3/2,1/2o]′→[4S3/2o]′ transitions, in the 2p3 configuration of a nitrogenlike isoelectronic sequence (from Z=7 to Z=79) are calculated by using a large-scale multiconfiguration Dirac-Fock method. The scaling laws of the excitation energies, fine-structure splittings, forbidden transition rates, line strengths, and ratios of line intensities varying with Z are investigated. The underlying physical mechanism leading to the change of the scaling laws from low Z to high Z are discussed. The calculated transition probabilities and scaling laws are expected to be useful for astrophysical and plasma physical applications.

关键词： ATOMIC transition probabilities RESEARCH DIRAC equation FOCK spaces SPIN excitations ISOELECTRONIC sequences PHASE transformations (Physics)

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Precision calculation of low-energy electron-impact excitation cross sections of helium among the ground and excited states

引用

Physical Review A 2015年第2期91卷 022707-022707页

作者： De-Ling Zeng Xiang Gao Xiao-Ying Han Jia-Ming Li Key Laboratory for Laser Plasmas (Ministry of Education) and Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai 200240 China Beijing Computational Science Research Center Beijing 100084 China Institute of Applied Physics and Computational Mathematics Beijing 100088 China Department of Physics and Center for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China Collaborative Innovation Center of Quantum Matter Beijing 100084 China

Low-energy electron-impact cross sections of helium among the ground and some low excited states are calculated using the R-matrix method. The convergences of the cross sections are checked systematically by using five sets of high-quality target states; i.e., including 5, 11, 19, 29, and 39 physical target states, respectively. Our calculated cross sections are in excellent agreement with the benchmark high-resolution experimental data. Compared with the recommended theoretical data, there is a deviation of about 6%, which suggests the recommended data may need a revision. Based on our calculation results, the influence of the Rydberg target states on the collision cross sections of the excited states is found to be similar to the case of the ground state; i.e., the amplitude of resonance structures will decrease with respect to the principal quantum number n of Rydberg target states. This result should be very useful for providing the cross-section data in the whole energy regions with high quality, which would be of great importance in related scientific fields.

关键词： HELIUM ELECTRONIC excitation EXCITED states GROUND state (Quantum mechanics) CROSS sections (Nuclear physics) QUANTUM numbers

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Origin of Ferroelectricity and Superconductivity with Nontrivial Electronic Topology in Fluorinated Nb2N

arXiv

引用

arXiv 2024年

作者： Yin, Xin-Zhu Jiao, Na Lu, Jinlian Zheng, Meng-Meng Lu, Hong-Yan Zhang, Ping School of Physics and Physical Engineering Qufu Normal University Qufu273165 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Department of Physics Yancheng Institute of Technology Jiangsu Yancheng224051 China

Two-dimensional (2D) intrinsic superconductors with nontrivial topological band and vertical ferroelectricity exhibit fascinating characteristics to achieving electrostatic control of quantum phases. While, only a few such 2D materials have been theoretically predicted. In this work, based on first-principles calculations, we explore the superconductivity and ferroelectric properties in fluorinated 2D Nb2N. In the stable Nb2NF2, H3-Nb2NF2 breaks the spatial inversion symmetry, exhibiting vertical ferroelectric. More interestingly, it not only possesses intrinsic superconductivity with superconducting transition temperatures (Tc) of 10 K, but also exhibits nontrivial band topology. While, H1-Nb2NF2 shows topological band and superconductivity with Tc of 32 K, surpassing most of 2D conventional topological superconductors’ candidates. Our research has enriched 2D superconducting materials with nontrivial band topology and ferroelectric properties, and provided a theoretical basis for the preparation of devices switching between superconducting and ferroelectric states with external electric field. Copyright © 2024, The Authors. All rights reserved.

关键词： Niobium compounds

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Completeness of solutions of Bethe's equations

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Physical Review E 2013年第5期88卷 052113-052113页

作者： Wenrui Hao Rafael I. Nepomechie Andrew J. Sommese Mathematical Biosciences Institute The Ohio State University 1735 Neil Avenue Columbus Ohio 43210 USA Physics Department P.O. Box 248046 University of Miami Coral Gables Florida 33124 USA Department of Applied and Computational Mathematics and Statistics University of Notre Dame 163 Hurley Hall Indiana 46556 USA

We consider the Bethe equations for the isotropic spin-1/2 Heisenberg quantum spin chain with periodic boundary conditions. We formulate a conjecture for the number of solutions with pairwise distinct roots of these equations, in terms of numbers of so-called singular (or exceptional) solutions. Using homotopy continuation methods, we find all such solutions of the Bethe equations for chains of length up to 14. The numbers of these solutions are in perfect agreement with the conjecture. We also discuss an indirect method of finding solutions of the Bethe equations by solving the Baxter T-Q equation. We briefly comment on implications for thermodynamical computations based on the string hypothesis.

关键词： COMPLETENESS theorem EQUATIONS -- Numerical solutions BOUNDARY value problems HEISENBERG model HOMOTOPY theory THERMODYNAMICS

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