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Is Objectivity Really an Objective Concept?

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Annals of Applied Mathematics 2022年第4期38卷 441-492页

作者： Nicolas Van Goethem Universidade de Lisboa Faculdade de CienciasDepartamento de MatematicaCMAFcIOAlameda da UniversidadeC61749-016 LisboaPortugal

Objectivity is the name given to covariance with respect to changes in observers by the action of the Euclidean group and is a central concept for mathematical modelling in Physics and Continuum ***,this notion is delicate and therefore hard to understand by both mechanicians and mathematicians,precisely because it resides at the junction of the two disciplines and hence appeals to knowledge and notions from both fields to become *** a first part(“behind objectivity”)some classical notions of objectivity and frame-dependence are presented,discussed and critically revisited with the purpose to introduce in a second part(“beyond objectivity”)a novel modelling approach in incompatible elasticity,based on intrinsic and geometric concepts,related but distinct from conventional *** contribution is primarily conceived to assist students,academics and researchers,mathematicians in particular,to find their way through some difficult and often ill-understood concepts of Physics and Continuum mechanics,since objectivity still remains nowadays a profound concept that deserves our attention.

关键词： Frame indifference objectivity elasticity incompatibility

Severe Acute Hepatitis of Unknown Origin in Children: What Do We Know Today?

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Journal of Clinical and Translational Hepatology 2022年第4期10卷 711-717页

作者： María Teresa Pérez-Gracia Antonio Tarín-Pelló Beatriz Suay-García Área de Microbiología.departamento de Farmacia Universidad Cardenal Herrera-CEU.CEU UniversitiesAlfara del Patri-arca(Valencia)Spain ESI International Chair@CEU-UCH Departamento de MatemáticasFísica y Ciencias TecnológicasUniversidad Cardenal Herrera-CEUCEU UniversitiesAlfara del Patriarca(Valencia)Spain

In May 2022, the UK International Health Regulations National Focal Point notified World Health Organization of 176 cases of severe acute hepatitis of unknown etiology in children under 10 years of age. From that moment on, cases of severe acute hepatitis of unknown origin in children began to be reported in several countries. As of June 17, 2022, a total of 991 cases had been reported in 35 countries worldwide, 50 children needed a liver transplant and 28 patients died. According to information published by ECDC, 449 cases have been detected in 21 EU countries. The children were between 1 month and 16 years of age. Adenovirus was detected in 62.2% of the analyzed samples. So far, the cause of these cases is unknown and many hypotheses remain open, but hepatitis A-E viruses and COVID-19 vaccines have been ruled out. A possible hypothesis has been published to explain the cause of these cases of severe hepatitis, according to which it could be a consequence of adenovirus infection in the intestine in healthy children previously infected with SARS-CoV-2. No other clear epidemiological risk factors have been identified to date. Thus, at this time, the etiology of the current cases of hepatitis remains under active investigation.

关键词： Hepatitis Children Unknown origin SARS-CoV-2 Adenovirus

Transient Behavior of a System Composed of Conductive Thin Wire Structures Excited by Harmonic and Lightning Type Signals

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Journal of Electromagnetic Analysis and Applications 2014年第11期6卷 342-357页

作者： Eduardo Faleiro Gabriel Asensio Daniel García Gregorio denche Jorge Moreno departamento de Física Aplicada ETSIDI Universidad Politécnica de Madrid Madrid Spain departamento de matemática Aplicada ETSIDI Universidad Politécnica de Madrid Madrid Spain departamento de Ingeniería Eléctrica ETSIDI Universidad Politécnica de Madrid Madrid Spain

The transient response of a system of independent electrodes buried in a semi-infinite conducting medium is studied. Using a simple and versatile numerical scheme written by the authors and based on the Electric Field Integral Equation (EFIE), the effect caused by harmonic signals ranging on frequency from Hz to hundred of MHz, and also by lightning type driving signal striking at a remote point far from the conductors, is extensively studied. The value of the scalar potential appearing on the electrodes as a function of the frequency of the applied signal is one of the variables investigated. Other features such as the input impedance at the injection point of the signal and the Ground Potential Rise (GPR) over the electrode system are also discussed.

关键词： Transferred Potentials Thin Wire Structures Lightning Pulses Electric Field Integral Equation Method of Moments

Ξ^-t quasibound state instead of ΛΛnn bound state

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Chinese Physics C 2020年第2期44卷 94-100页

作者： H.Garcilazo A.Valcarce J.Vijande Escuela Superior de Física y matemáticas Instituto Politécnico NacionalEdificio 907738 México D.F.Mexico departamento de Física Fundamental Universidad de Salamanca37008 SalamancaSpain departamento de Física Atómica Molecular y NuclearUniversidad de Valencia(UV)and IFIC(UV-CSIC)46100 ValenciaSpain IRIMED Joint Research Unit(IIS La Fe-UV) 46100 ValenciaSpain

The coupledΛΛnn-Ξ-pnn system was studied to investigate whether the inclusion of channel coupling is able to bind theΛΛnn *** use a separable potential three-body model of the coupledΛΛnn-Ξ-pnn system and a variational four-body calculation with realistic *** results exclude the possibility of aΛΛnn bound state by a large ***,we found aΞ-t quasibound state above theΛΛnn threshold.

关键词： baryon-baryon interactions few-body systems Faddeev equations

The Crank-Nicolson Hermite Cubic Orthogonal Spline Collocation Method for the Heat Equation with Nonlocal Boundary Conditions

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Advances in Applied Mathematics and Mechanics 2013年第4期5卷 442-460页

作者： B.Bialecki G.Fairweather J.C.Lopez-Marcos department of AppliedMathematics and Statistics Colorado School of MinesGoldenCO 80401USA Mathematical Reviews American Mathematical Society416 Fourth StreetAnn ArborMI 48103USA departamento de matem´atica Aplicada Universidad de ValladolidValladolidSpain

We formulate and analyze the Crank-Nicolson Hermite cubic orthogonal spline collocation method for the solution of the heat equation in one space variable with nonlocal boundary conditions involving integrals of the unknown solution over the spatial *** an extension of the analysis of Douglas and Dupont[23]for Dirichlet boundary conditions,we derive optimal order error estimates in the discrete maximum norm in time and the continuous maximum norm in *** discuss the solution of the linear system arising at each time level via the capacitance matrix technique and the package COLROWfor solving almost block diagonal linear *** present numerical examples that confirm the theoretical global error estimates and exhibit superconvergence phenomena.

关键词： Heat equation nonlocal boundary conditions orthogonal spline collocation Hermite cubic splines convergence analysis superconvergence

Numerical Simulation of Bed Load and Suspended Load Sediment Transport Using Well-Balanced Numerical Schemes

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Communications on Applied Mathematics and Computation 2023年第2期5卷 885-922页

作者： J.C.González-Aguirre J.A.González-Vázquez J.Alavez-Ramírez R.Silva M.E.Vázquez-Cendón División Acádemica de Ciencias Básicas Universidad Juárez Autónoma de TabascoCarr.Cunduacán-Jalpa de Mendéz KM.1CP 86690CunduacánTabascoMexico Universidad Autónoma Metropolitana-Unidad Iztapalapa Av.San Rafael Atlixco no.186Mexico CityMexico Instituto de Ingeniería Universidad Nacional Autónoma de México04510 Mexico CityMexico departamento de matemática Aplicada Universidade de Santiago de Compostela15706 Santiago de CompostelaSpain

Sediment transport can be modelled using hydrodynamic models based on shallow water equations coupled with the sediment concentration conservation equation and the bed con-servation *** complete system of equations is made up of the energy balance law and the Exner *** numerical solution for this complete system is done in a seg-regated ***,the hyperbolic part of the system of balance laws is solved using a finite volume *** ways to compute the numerical flux have been considered,the Q-scheme of van Leer,the HLLCS approximate Riemann solver,and the last one takes into account the presence of non-conservative products in the *** discretisation of the source terms is carried out according to the numerical flux *** the second stage,the bed conservation equation is solved by using the approximation computed for the system of balance *** numerical schemes have been validated making comparisons between the obtained numerical results and the experimental data for some physical *** numerical results show a good agreement with the experimental data.

关键词： Sediment transport Suspended load Bed load Finite volume method Numerical simulation Well-balanced schemes

Convex Mean Curvature Flow with a Forcing Term in Direction of the Position Vector

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Acta Mathematica Sinica,English Series 2012年第2期28卷 313-332页

作者： Guang Han LI Jing MAO Chuan Xi WU School of Mathematics and Computer Science Key Laboratory of Applied Mathematics of Hubei ProvinceHubei UniversityWuhan 430062P.R.China departamento de matemática Instituto Superior TecnicoTechnical University of LisbonEdifício CiênciaPiso 3Av.Rovisco Pais1049-001 LisboaPortugal Institute of Mathematics Hubei UniversityWuhan 430062P.R.China

A smooth, compact and strictly convex hypersurface evolving in R^n＋1 along its mean curvature vector plus a forcing term in the direction of its position vector is studied in this paper. We show that the convexity is preserving as the case of mean curvature flow, and the evolving convex hypersurfaces may shrink to a point in finite time if the forcing term is small, or exist for all time and expand to infinity if it is large enough. The flow can converge to a round sphere if the forcing term satisfies suitable conditions which will be given in the paper. Long-time existence and convergence of normalization of the flow are also investigated.

关键词： Evolution equation mean curvature flow forcing term normalization

Effect of variations in the polar and azimuthal angles of coarse particles on the structure of drainage channels in thickened beds

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International Journal of Minerals,Metallurgy and Materials 2023年第12期30卷 2321-2333页

作者： Cuiping Li Gezhong Chen Zhu’en Ruan Raimund Bürger Yuan Gao Hezi Hou Hui Wang Key Laboratory of the Ministry of Education of China for High-efficient Mining and Safety of Metal Mines University of Science and Technology BeijingBeijing 100083China Shunde Innovation School University of Science and Technology BeijingFoshan 528399China CI2MA and departamento de Ingeniería matemática Facultad de Ciencias Físicas y MatematicasUniversidad de ConcepcionCasilla 160-CConcepciónChile School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China School of Civil and Resource Engineering University of Science and Technology BeijingBeijing 100083China

The 3D reconstruction and quantitative characterization of drainage channels and coarse tailings particles in a bed were conducted in this *** influence of variations in the azimuthal angle(θ)and polar angle(φ)of coarse particles on drainage channel structure was analyzed,and the drainage mechanism of the bed was *** showed that water discharge in the bed reduced the size of pores and throat channels,increasing slurry *** throat channel structure was a key component of the drainage ***φandθof particles changed predominantly along the length *** changes inφhad a cumulative plugging effect on the drainage channel and increased the difficulty of water *** rake and rod formed a shear ring in the tailings bed with shear,and theθdistribution of particles changed from disorderly to orderly during the rotation *** drainage channel was squeezed during the shearing process with the change inθ,which broke the channel structure,encouraged water discharge in the bed,and facilitated a further increase in slurry *** findings of this work are expected to offer theoretical guidance for preparing high-concentration underflow in the tailings thickening process.

关键词： tailings thickening coarse particle azimuthal angle polar angle drainage channels

An Optimal Control Approach to HIV Immunology

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Applied Mathematics 2015年第6期6卷 1115-1130页

作者： Edilson F. Arruda Claudia M. Dias Camila V. de Magalh&atilde es Dayse H. Pastore Roberto C. A. Thomé Hyun Mo Yang Instituto Alberto Luiz Coimbra de Pó s Graduaç &atilde o e Pesquisa de Engenharia Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil Instituto Multidisciplinar Universidade Federal Rural do Rio de Janeiro Nova Igua&ccedil u Brazil departamento de matemá tica Centro Federal de Educa&ccedil &atilde o Tecnoló gica Celso Suckow da Fonseca Rio de Janeiro Brazil departamento de matemá tica Aplicada Universidade Estadual de Campinas Campinas Brazil

This paper introduces a mathematical model which describes the dynamics of the spread of HIV in the human body. This model is comprised of a system of ordinary differential equations that involve susceptible cells, infected cells, HIV, immune cells and immune active cells. The distinguishing feature in the proposed model with respect to other models in the literature is that it takes into account cells that represent two distinct mechanisms of the immune system in the defense against HIV: the non-HIV-activated cells and the HIV-activated cells. With a view at minimizing the side effects of a treatment that employs a drug combination designed to attack the HIV at various stages of its life cycle, we introduce control variables that represent the infected patient’s medication. The optimal control rule that prescribes the medication for a given time period is obtained by means of Pontryagin’s Maximum Principle.

关键词： HIV Mathematical Modelling Optimal Control Pontryagin’s Maximum Principle