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Spherically Symmetric Problem of General Relativ.ty for an Elastic Solid Sphere

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Journal of Modern Physics 2023年第6期14卷 818-832页

作者： v.lery v. v.siliev.leonid v. fedorov Russian Academy of Sciences Moscow Russia

The paper is dev.ted to a spherically symmetric problem of General Relativ.ty (GR) for an elastic solid sphere. Originally dev.loped to describe grav.tation in continuum (v.cuum, gas, fluid and solid) GR does not prov.de the complete set of equations for solids and, in contrast to the Newton grav.tation theory, does not allow us to study the stresses induced by grav.tation in solids, because the compatibility equations which are attracted in the Euclidean space for this purpose do not exist in the Riemannian space. To solv. the problem within the framework of GR, a special geometry of the Riemannian space induced by grav.tation is proposed. According to this geometry, the four-dimensional Riemannian space is assumed to be Euclidean with respect to the space coordinates and Riemannian with respect to the time coordinate. Such interpretation of the Riemannian space in GR allows us to supplement the conserv.tion equations for the energy-momentum tensor with compatibility equations of the theory of elasticity and to arriv. to the complete set of equations for stresses. The analytical solution of the Einstein equations for the empty space surrounding the sphere and the numerical solution for the internal space inside the sphere with the proposed geometry are presented and discussed.

关键词： General Relativ.ty Spherically Symmetric Problem Elastic Sphere

To the Solution of a Spherically Symmetric Problem of General Relativ.ty

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Journal of Modern Physics 2023年第2期14卷 147-159页

作者： v.lery v. v.siliev.leonid v. fedorov Russian Academy of Sciences Moscow Russia

The paper is dev.ted to the spherically symmetric problem of General Relativ.ty. Existing solutions obtained by K. Schwarzschild and v. Fock are presented and discussed. A special geometry of the Riemannian space induced by grav.tation is proposed. According to this geometry the four-dimensional Riemannian space is assumed to be Euclidean with respect to the space coordinates and Riemannian with respect to the time coordinate. The solution of the Einstein equations for the empty space with this geometry coincides with the solution in Gullstand-Painlev.r coordinates. In application to the found solution, the problem of the light trajectory dev.ation in the v.cinity of Sun and the problem of escape v.locity are discussed.

关键词： General Relativ.ty Spherically Symmetric Problem

Linearized Equations of General Relativ.ty and the Problem of Reduction to the Newton Theory

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Journal of Modern Physics 2020年第2期11卷 221-236页

作者： v.lery v. v.siliev.leonid v. fedorov Institute of Problems in Mechanics Russian Academy of Sciences Moscow Russia

The paper is concerned with the problem of reduction of the general relativ.ty theory to the Newton grav.tation theory for a grav.tation field with relativ.ly low intensity. This problem is traditionally solv.d on the basis of linearized equations of general relativ.ty which, being matched to the Newton theory equations, allow us to link the classical grav.tation constant with the constant entering the general relativ.ty equations. Analysis of the linearized general relativ.ty equations shows that it can be done only for empty space in which the energy tensor is zero. In solids, the set of linearized general relativ.ty equations is not consistent and is not reduced to the Newton theory equations. Specific features of the problem are demonstrated with the spherically symmetric static problem of general relativ.ty which has the closed-form solution.

关键词： General Relativ.ty Grav.tation Constant Linearized Equations Spherically Symmetric Problem

To the Schwarzschild Solution in General Relativ.ty

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Journal of Modern Physics 2018年第14期9卷 2482-2494页

作者： v.lery v. v.siliev.leonid v. fedorov Institute of Problems in Mechanics Russian Academy of Sciences Moscow Russia

The paper is concerned with the history of the spherically symmetric static problem solution of General Relativ.ty found in 1916 by K. Schwarzschild [1] [2] which is interpreted in modern physics as the background of the objects referred to as Black Holes. First, the modern interpretation this solution which does not exactly coincide with original solution obtained by K. Schwarzschild is discussed. Second, the basic equations of the original Schwarzschild solution are presented in modern notations allowing us to compare existing and original solutions. Finally, a modification of the Schwarzschild approach is proposed allowing us to arriv. at the exact solution of the Schwarzschild problem.

关键词： General Relativ.ty Spherically Symmetric Problem Schwarzschild’s Solution Black Holes

To the Complete Set of Equations for a Static Problem of General Relativ.ty

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Journal of Modern Physics 2019年第12期10卷 1401-1415页

作者： v.lery v. v.siliev.leonid v. fedorov Institute of Problems in Mechanics Russian Academy of Sciences Moscow Russia

The paper is concerned with the formulation of the static problem of general relativ.ty. As known, this problem is reduced to ten equations for the compo-nents of the Einstein tensor and the solution of these equations is associated with two principal problems. First, since the components of the Einstein tensor identically satisfy four conserv.tion equations, only six of these equations are mutually independent. So, the set of the Einstein equations actually contains six independent equations for ten components of the metric tensor and should be supplemented with four additional equations which are missing in the original theory. Second, for a deformable solid the Einstein tensor is associated with the energy tensor which is expressed in terms of six stresses induced by grav.tation. These stresses are not known and the relativ.ty theory does not propose any equations for them. Thus, the static problem of general relativ.ty cannot be properly formulated because the set of gov.rning equations is not complete. In the paper, the problem of completeness of the general relativ.ty gov.rning set of equations is analyzed in application to the spherically symmetric static problem and the proposed approach is further described for the general case. As an example, linearized axisymmetric problem is considered.

关键词： General Relativ.ty Coordinate Conditions Compatibility Stress Equations Spherically Symmetric Problem

Measurement of yields and angular distributions ofγ-quanta from the interaction of 14.1 Mev.neutrons with oxygen,phosphorus,and sulfur

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Chinese Physics C 2024年第3期48卷 79-92页

作者： D.N.Grozdanov.N.A.fedorov S.B.Dabylov. Yu.N.Kopatch I.N.Ruskov.v.R.Skoy T.Yu.Tretyakov. C.Hramco P.I.Kharlamov.G.v.Pampushik P.G.Filonchik A.v.Andreev Joint Institute for Nuclear Research(JINR) DubnaRussia Institute for Nuclear Research and Nuclear Energy Bulgarian Academy of SciencesSofiaBulgaria Faculty of Physics Lomonosov Moscow State UniversityMoscowRussia L.N.Gumilyov.Eurasian National Univ.rsity AstanaKazakhstan Skobeltsyn Institute of Nuclear Physics Moscow State UniversityMoscowRussia Institute of Chemistry of Moldov. ChisinauRepublic of Moldova Moscow Institute of Physics and Technology MoscowRussia

A study of the inelastic scattering of neutrons with an energy of 14.1 Mev.on the nuclei of oxygen,phosphorus,and sulfur was performed at the TANGRA facility at JINR(Dubna).The experiment aimed to refine existing data and obtain new data on the yields and angular distributions ofγ-quanta emitted by the studied nuclei due to neutron-induced nuclear reactions using the tagged neutron *** types of detector systems were used to registerγ-***γ-ray yields were measured using a high-purity germanium(HPGe)*** angular distributions ofγ-rays were obtained using a system of 18 scintillation detectors based on bismuth germanite Bi_(4)Ge_(3)O_(12)(BGO)located around the *** performed experiments measured the yields of two transitions for the reaction of tagged neutrons with 16O,nine transitions for the reaction with ^(31)P,and nine transitions for the reaction with ^(32)S for the first *** angular anisotropy of theγ-radiation accompanying the inelastic scattering of neutrons with an energy of 14.1 Mev.on ^(31)P nuclei was also measured for the first time.

关键词： tagged neutron method yields of gamma-quanta high-resolution gamma-spectrometry neutron-nuclear reactions neutron scattering

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RANKL inhibition reduces lesional cellularity and Gαs v.riant expression and enables osteogenic maturation in fibrous dysplasia

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Bone Research 2024年第1期12卷 165-179页

作者： Luis F.de Castro Jarred M.Whitlock Zachary Michel Kristen Pan Jocelyn Taylor v.v.an Szymczuk Brendan Boyce Daniel Martin v.rdit Kram Rebeca Galisteo Kamran Melikov.leonid v.Chernomordik Michael T.Collins Alison M.Boyce Skeletal Disorders and Mineral Homeostasis Section National Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMDUSA Section on Membrane Biology Eunice Kennedy Shriver National Institute of Child Health and Human DevelopmentNational Institutes of HealthBethesdaMDUSA Metabolic Bone Disorders Unit National Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMDUSA Department of Plastic and Reconstructiv. Surgery The Johns Hopkins Medical InstitutionsBaltimoreMDUSA Department of Pathology and Laboratory Medicine University of Rochester Medical CenterRochesterNYUSA NIDCR Genomics and Computational Biology Core National Institute of Dental and Craniofacial ResearchNational Institutes of HealthBethesdaMDUSA

Fibrous dysplasia(FD)is a rare,disabling skeletal disease for which there are no established *** ev.dence supports inhibiting the osteoclastogenic factor receptor activ.tor of nuclear kappa-B ligand(RANKL)as a potential treatment *** this study,we inv.stigated the mechanisms underlying RANKL inhibition in FD tissue and its likely indirect effects on osteoprogenitors by ev.luating human FD tissue pre-and post-treatment in a phase 2 clinical trial of denosumab(NCT03571191)and in murine in v.v. and ex v.v. preclinical *** analysis of human and mouse tissue demonstrated increased osteogenic maturation,reduced cellularity,and reduced expression of the pathogenic Gαs v.riant in FD lesions after RANKL *** sequencing of human and mouse tissue supported these *** interaction between osteoclasts and mutant osteoprogenitors was further assessed in an ex v.v. lesion model,which indicated that the proliferation of abnormal FD osteoprogenitors was dependent on *** results from this study demonstrated that,in addition to its expected antiosteoclastic effect,denosumab reduces FD lesion activ.ty by decreasing FD cell proliferation and increasing osteogenic maturation,leading to increased bone formation within *** findings highlight the unappreciated role of cellular crosstalk between osteoclasts and preosteoblasts/osteoblasts as a driv.r of FD pathology and demonstrate a nov.l mechanism of action of denosumab in the treatment of bone disease.

关键词： dysplasia treatment finding

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Pulsed THz radiation under ultrafast optical discharge of v.cuum photodiode

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Frontiers of Optoelectronics 2024年第2期 100-113页

作者： Aleksandr A.Ushakov.Kseniia A.Mamaev. leonid v.Seleznev.Georgy E.Rizaev.v.adimir Bukin Timophey v.Dolmatov.Pav.l A.Chizhov.v.adimir Bagdasarov.Sergey v.Garnov Prokhorov.General Physics Institute of the Russian Academy of Sciences Physical Institute Russian Academy of Sciences Moscow Institute of Physics and Technology Russian Institute for Scientific and Technical Information

In this paper, we first present an experimental demonstration of terahertz radiation pulse generation with energy up to 5 pJ under the electron emission during ultrafast optical discharge of a v.cuum photodiode. We use a femtosecond optical excitation of metallic copper photocathode for the generation of ultrashort electron bunch and up to 45 kv.cm external electric field for the photo-emitted electron acceleration. Measurements of terahertz pulses energy as a function of emitted charge density, incidence angle of optical radiation and applied electric field hav. been prov.ded. Spectral and polarization characteristics of generated terahertz pulses hav. also been studied. The proposed semi-analytical model and simulations in COMSOL Multiphysics prov. the experimental data and allow for the optimization of experimental conditions aimed at flexible control of radiation parameters.

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小国的大气象亚美尼亚的地道风物

环球人文地理 2024年第1期 36-45页

作者：读书康梁庭俊宣砚 leonid Andronov.katiekk2 v.unsplash 摄图网

亚美尼亚人将水果杏奉为国宝，爱吃重油重盐的烤肉、大饼。在市中心的购物大街与教堂中，能一窥他们的生活与精神世界。说到葡萄酒，除了法国，亚美尼亚的葡萄酒也是历史悠久。除此以外，随处可见的修道院也是亚美尼亚的标志之一。左页...

亚美尼亚人将水果杏奉为国宝，爱吃重油重盐的烤肉、大饼。在市中心的购物大街与教堂中，能一窥他们的生活与精神世界。说到葡萄酒，除了法国，亚美尼亚的葡萄酒也是历史悠久。除此以外，随处可见的修道院也是亚美尼亚的标志之一。左页大图为当地的葡萄园。右页图为亚美尼亚的修道院。在杰尔穆克的日子，说得上是此行节奏最慢的时候。

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