March 17th, 2021

лошадь, диаграмма, Фейнман

Тимоти Бойер на Ландау-Лифшица наезжает:))

Relativity and Radiation Balance for the Classical Hydrogen Atom in Classical Electromagnetic Zero-Point Radiation: https://arxiv.org/abs/2103.09084
Timothy H. Boyer
Here we review the understanding of the classical hydrogen atom in classical electromagnetic zero-point radiation, and emphasize the importance of special relativity. The crucial missing ingredient in earlier calculational attempts (both numerical and analytic) is the use of valid approximations to the full relativistic analysis. It is pointed out that the nonrelativistic time Fourier expansion coefficients given by Landau and Lifshitz are in error as the electromagnetic description of a charged particle in a Coulomb potential, and, because of this error, Marshall and Claverie's conclusion regarding the failure of radiation balance is invalid. Rather, using Marshall and Claverie's calculations, but restricted to lowest nonvanishing order in the orbital eccentricity (where the nonrelativistic orbit is a valid approximation to the fully relativistic electromagnetic orbit) radiation balance for classical electromagnetic zero-point radiation is shown to hold at the fundamental frequencies and associated first overtones.
Comments: 31 pages
Subjects: Classical Physics (physics.class-ph); History and Philosophy of Physics (physics.hist-ph); Quantum Physics (quant-ph)
Journal reference: European Journal of Physics 42, 025205(22) (2021)
лошадь, диаграмма, Фейнман

Проект передатчика для МРТ при 10.5 Тесла

Design of a Self Decoupled 16 Channel Transmitter for Human Brain MRI at 447MHz: https://arxiv.org/abs/2103.07516
Nader Tavaf, Jerahmie Radder, Russell L. Lagore, Steve Jungst, Andrea Grant, Kamil Ugurbil, Gregor Adriany, Pierre Francois Van de Moortele
Transmitter arrays play a critical role in ultra high field Magnetic Resonance Imaging (MRI), especially given the advantages made possible via parallel transmission (pTx) techniques. One of the challenges in design and construction of transmit arrays has traditionally been finding effective strategies for decoupling elements of the transmit array. Here, we present the design of the first self-decoupled, loop-based transmit array for human brain MRI at 10.5T / 447MHz. We demonstrate, using full-wave electromagnetic simulations, effective decoupling of the transmit elements without requiring the conventional overlap or inductive decoupling techniques.