Frontiers in Physics最新文献

{"title":"Automated size-specific dosimetry for chest posterior–anterior projection radiography","authors":"An Dedulle, Niki Fitousi, Nicholas Marshall, Hilde Bosmans","doi":"10.3389/fphy.2024.1441316","DOIUrl":"https://doi.org/10.3389/fphy.2024.1441316","url":null,"abstract":"IntroductionChest radiography is a frequently performed examination, and therefore, accurate patient dosimetry is important. One means of increasing dosimetric accuracy is through the use of size-specific dosimetry, and the aim of this work was to determine which patients would benefit from such a methodology applied in chest posterior–anterior (PA) projection radiography.MethodsA database of 44 voxel models was created from CT scans, representing adults with BMI from underweight, normal, overweight, and obese classes. Monte Carlo simulation was performed to generate dose conversion factors for each model. Correlation curves of the dose conversion factors with water equivalent diameter (WED) of the 44 voxel phantoms were obtained. A total of 8,536 chest PA examinations acquired between 2015 and 2019 using three X-ray systems were then retrospectively collected; 4,748 men (median age: 61 ± 21 years) and 3,788 women (median age: 60 ± 23 years). The WED of the patients was estimated from the ratio of detector air-kerma to incident air-kerma, using parameters in the DICOM header of the images. For all patients, a size-specific conversion factor was selected automatically using the relation between WED and dose conversion factor determined for the phantoms. The size-specific organ doses and effective doses were calculated based on these conversion factors, and then compared to the standard effective dose calculation with a paired test.ResultsThe lung doses ranged from 7 μGy to 96 μGy and had a good correlation with patient size in terms of WED (<jats:italic>p</jats:italic> &amp;lt; 0.01, R² between 0.52 and 0.77). The doses for thyroid ranged from 2 μGy to 42 μGy and correlated strongly with the patient size (p &amp;lt; 0.01, R² between 0.65 and 0.85). Breast doses ranged from 2 μGy to 13 μGy, and the correlation with the patient size was weak (<jats:italic>p</jats:italic> &amp;lt; 0.01, R<jats:sup>2</jats:sup> between 0.01 and 0.28). The size-specific effective dose ranged from 4 μSv to 42 μSv. The difference between the size-specific and standard effective dose ranged from −35% to 69% (<jats:italic>p</jats:italic> &amp;lt; 0.01), with differences exceeding ± 20% for 37% of the cases.DiscussionIn conclusion, the method presented in this study enables automated size-specific dosimetry, within the proposed maximum deviation of ± 20%, and should be considered for routine application.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"15 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation and theoretical analysis of pattern dynamics for the fractional-in-space Schnakenberg model","authors":"Ji-Lei Wang, Yu-Xing Han, Qing-Tong Chen, Zhi-Yuan Li, Ming-Jing Du, Yu-Lan Wang","doi":"10.3389/fphy.2024.1452077","DOIUrl":"https://doi.org/10.3389/fphy.2024.1452077","url":null,"abstract":"Effective exploration of the pattern dynamic behaviors of reaction–diffusion models is a popular but difficult topic. The Schnakenberg model is a famous reaction–diffusion system that has been widely used in many fields, such as physics, chemistry, and biology. Herein, we explore the stability, Turing instability, and weakly non-linear analysis of the Schnakenberg model; further, the pattern dynamics of the fractional-in-space Schnakenberg model was simulated numerically based on the Fourier spectral method. The patterns under different parameters, initial conditions, and perturbations are shown, including the target, bar, and dot patterns. It was found that the pattern not only splits and spreads from the bar to spot pattern but also forms a bar pattern from the broken connections of the dot pattern. The effects of the fractional Laplacian operator on the pattern are also shown. In most cases, the diffusion rate of the fractional model was higher than that of the integer model. By comparing with different methods in literature, it was found that the simulated patterns were consistent with the results obtained with other numerical methods in literature, indicating that the Fourier spectral method can be used to effectively explore the dynamic behaviors of the fractional Schnakenberg model. Some novel pattern dynamics behaviors of the fractional-in-space Schnakenberg model are also demonstrated.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"103 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analytical solution of steady reconnection outflows in a time-varying three-dimensional reconnection model with generalized spatiotemporal distributions","authors":"Y. L. Chen, Y. Wang, F. S. Wei, X. S. Feng, Z. L. Zhou, B. Y. Wang, P. B. Zuo, C. W. Jiang, Y. X. Gu, L. D. Wang, X. J. Song, X. J. Xu","doi":"10.3389/fphy.2024.1439949","DOIUrl":"https://doi.org/10.3389/fphy.2024.1439949","url":null,"abstract":"Magnetic reconnection is a fundamental mechanism for energy conversion in the realms of space physics, astrophysics, and plasma physics. Over the past few decades, obtaining analytical solutions for three-dimensional (3D) magnetic reconnection has remained a challenging endeavor. Due to the complexity and nonlinearity of the equations, analytical solutions can only be obtained when specific spatiotemporal distributions of magnetic fields or plasma flows are provided. Particularly, the evolution of reconnection flows in time-dependent 3D reconnection has not been analytically discussed. Additionally, quasi-steady magnetic reconnection persisting for several hours can be observed in the turbulent solar wind, which raises an important question: can steady reconnection flows theoretically exist in a time-dependent 3D magnetic reconnection model? In this study, a generalized analytical model for time-dependent kinematic 3D magnetic reconnection has been constructed. In the framework of pure analytical approach, it is firstly demonstrated that steady reconnection outflows can theoretically exist within a time-varying magnetic field. We have also analytically discussed the possibility of the existence of quasi-steady reconnection flows in 3D magnetic reconnection for turbulent magnetic fields in the solar wind. These findings broaden our understanding of the stability and necessary conditions for time-dependent 3D magnetic reconnection, offering new insights into quasi-steady reconnection phenomena in real cosmic environments.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"60 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bayesian optimization of proton generation in terawatt laser–CH2 cluster interactions within a plasma channel","authors":"Artem Kim, Mordechai Botton, Arie Zigler","doi":"10.3389/fphy.2024.1424755","DOIUrl":"https://doi.org/10.3389/fphy.2024.1424755","url":null,"abstract":"Improving the energy efficiency in generating high-energy proton or boron ions is crucial for advancing the feasibility of neutronless laser-based proton–boron (p-B<jats:sup>11</jats:sup>) fusion reactions. The primary objective of this work is to optimize the fusion energy efficiency of a proposed advanced p-B<jats:sup>11</jats:sup> fusion scheme. In the proposed scheme, an ultrashort laser pulse is guided by a plasma channel filled with carbon–hydrogen (CH<jats:sub>2</jats:sub>) clusters. The MeV protons are generated by the Coulomb explosion (CE) of the cluster, which, therefore, interact with surrounding boron to produce alpha particles. To evaluate the fusion energy efficiency under various conditions, 2D particle-in-cell (PIC) simulations are used, supplemented with analytical calculations and estimations. The Bayesian optimization (BO) algorithm is utilized to optimize the key interaction parameters. The BO approach allows us to identify optimal cluster and laser parameters that would have higher fusion energy efficiency.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"170 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219670","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"eXplainable artificial intelligence applied to algorithms for disruption prediction in tokamak devices","authors":"L. Bonalumi, E. Aymerich, E. Alessi, B. Cannas, A. Fanni, E. Lazzaro, S. Nowak, F. Pisano, G. Sias, C. Sozzi","doi":"10.3389/fphy.2024.1359656","DOIUrl":"https://doi.org/10.3389/fphy.2024.1359656","url":null,"abstract":"Introduction: This work explores the use of eXplainable artificial intelligence (XAI) to analyze a convolutional neural network (CNN) trained for disruption prediction in tokamak devices and fed with inputs composed of different physical quantities.Methods: This work focuses on a reduced dataset containing disruptions that follow patterns which are distinguishable based on their impact on the electron temperature profile. Our objective is to demonstrate that the CNN, without explicit training for these specific mechanisms, has implicitly learned to differentiate between these two disruption paths. With this purpose, two XAI algorithms have been implemented: occlusion and saliency maps.Results: The main outcome of this paper comes from the temperature profile analysis, which evaluates whether the CNN prioritizes the outer and inner regions.Discussion: The result of this investigation reveals a consistent shift in the CNN’s output sensitivity depending on whether the inner or outer part of the temperature profile is perturbed, reflecting the underlying physical phenomena occurring in the plasma.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"290 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evolution and governance of online public opinion during COVID-19: a hybrid approach using communication visualization, SIR modeling, and simulation validation","authors":"Lin Ren, Jiehua Zhang, Zhongyue Su, Fujun Lai, Deping Xiong","doi":"10.3389/fphy.2024.1462089","DOIUrl":"https://doi.org/10.3389/fphy.2024.1462089","url":null,"abstract":"IntroductionThis study investigates the mechanisms of public opinion dissemination and governance strategies during public health events, using a two-stage SIR model informed by the Information Cascade Theory.MethodsThe research employs Gephi visual analysis to identify principal nodes of public opinion and combines model simulations with dynamic propagation analysis to verify the model's precision and applicability.ResultsThe findings reveal that pivotal information nodes significantly accelerate the spread of public opinion, while ordinary nodes contribute to the natural attenuation of public discourse due to their strong spontaneous recovery capabilities. The simulation analysis further identifies the optimal timing for government intervention, particularly during the initial and peak phases of public opinion dissemination.DiscussionBased on the results, the study recommends strategies to strengthen the management of key opinion nodes, enhance public information literacy, optimize policy implementation, and utilize simulation tools to assist in public opinion management. These recommendations offer valuable theoretical and practical insights for managing public opinion during public health events.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"78 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New method for the investigation of mode coupling in graded-index polymer photonic crystal fibers using the Langevin stochastic differential equation","authors":"Svetislav Savović, Alexandar Djordjevich, Konstantinos Aidinis, Chen Chen, Rui Min","doi":"10.3389/fphy.2024.1479206","DOIUrl":"https://doi.org/10.3389/fphy.2024.1479206","url":null,"abstract":"The mode coupling in a graded-index polymer photonic crystal fiber (GI PPCF) with a solid core has been investigated using the Langevin equation. Based on the computer-simulated Langevin force, the Langevin equation is numerically integrated. The numerical solutions of the Langevin equation align with those of the time-independent power flow equation (TI PFE). We showed that by solving the Langevin equation, which is a stochastic differential equation, one can successfully treat a mode coupling in GI PPCFs, which is an intrinsically stochastic process. We demonstrated that, in terms of effectiveness, the Langevin equation is preferable compared to the TI PFE. The GI PPCF achieves the equilibrium mode distribution (EMD) at a coupling length that is even shorter than the conventional GI plastic optical fiber (POF). The application of multimode GI PCFs in communications and optical fiber sensor systems will benefit from these findings.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"5 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219673","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel image encryption method based on improved two-dimensional logistic mapping and DNA computing","authors":"Yuanlin Chen, Tianxiu Lu, Caiwen Chen, Yi Xiang","doi":"10.3389/fphy.2024.1469418","DOIUrl":"https://doi.org/10.3389/fphy.2024.1469418","url":null,"abstract":"In the digital era, the significance of cryptographic algorithms has grown significantly within the realm of cybersecurity. This research presents an innovative approach to image encryption that eliminates the security limitations of the conventional one-dimensional logistic mapping. This approach relies on an enhanced two-dimensional logistic-fraction hybrid chaotic mapping (2D-LFHCM) and deoxyribonucleic acid (DNA) computing. Initially, the improved 2D-LFHCM is utilized to effectively scramble the image by incorporating chaotic sequences. Then, two novel algebraic DNA computing rules are introduced to enhance diffusion encryption. Experimental findings show that this approach offers superior security performance, even with renowned attacks.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"60 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptive strategy for achieving fast synchronization between two memristor chaotic circuits without and with noisy perturbation","authors":"Binhua Yuan, Hui Xu, Lei Hu, Jie Wu","doi":"10.3389/fphy.2024.1445805","DOIUrl":"https://doi.org/10.3389/fphy.2024.1445805","url":null,"abstract":"This paper presents an innovative approach for achieving rapid synchronization between two memristor chaotic circuits (MCCs), both with and without noise perturbations. The proposed adaptive control strategy effectively handles the uncertainty in control gains by adhering to predesigned update law. Additionally, this protocol is non-chattering and differentiable, avoiding the use of conventional discontinuous functions such as signum and absolute value functions. This method successfully mitigates the tremors caused by discontinuous functions. We derive two sufficient criteria using finite-time Lyapunov and stochastic finite-time Lyapunov stability methods. Numerical results validate the theoretical analysis and demonstrate the influence of noise intensity on convergence speed. Furthermore, the results have an application in image encryption transmission.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"38 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219672","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Preparations for pB11 tests in the FF-2B dense plasma focus","authors":"Eric J. Lerner, Syed M. Hassan","doi":"10.3389/fphy.2024.1438880","DOIUrl":"https://doi.org/10.3389/fphy.2024.1438880","url":null,"abstract":"The dense plasma focus (DPF) device has great potential as a fusion energy generator using hydrogen-boron (pB11) fuel<jats:sup>1</jats:sup>. Experiments using deuterium have already demonstrated mean ion energies &amp;gt;200 keV, in the range needed for burning pB11<jats:sup>2</jats:sup>. To test that potential, we are preparing for experiments with hydrogen-boron fuel in the megampere DPF device, FF-2B. We plan to use isotopically-pure decaborane (B<jats:sub>10</jats:sub>H<jats:sub>14</jats:sub>) as the fuel source and have installed equipment for the safe handling and disposal of the toxic vapors from this material. High isotopic purity of the boron-11 is required to avoid generation of radioactive Be-7. While the main pB11 fusion reaction produces no neutrons, two side reactions do produce both neutrons and radioactive C-11. We show how these reaction products can be used with suitable detectors to provide accurate data on fusion yield, and the density and ion energy of the confined fusion-producing plasma.","PeriodicalId":12507,"journal":{"name":"Frontiers in Physics","volume":"10 1","pages":""},"PeriodicalIF":3.1,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142219677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}