February 19th, 2021

лошадь, диаграмма, Фейнман

Рамануджан, перенормировки и эффект Казимира

Это немного не по моей части, но, кажется, весьма клевая статейка.

From Ramanujan to renormalization: the art of doing away with divergences and arriving at physical results: https://arxiv.org/abs/2102.09371
Wolfgang Bietenholz
A century ago Srinivasa Ramanujan - the great self-taught Indian genius of mathematics - died, shortly after returning from Cambridge, UK, where he had collaborated with Godfrey Hardy. Ramanujan contributed numerous outstanding results to different branches of mathematics, like analysis and number theory, with a focus on special functions and series. Here we refer to apparently weird values which he assigned to two simple divergent series, ∑n≥1n and ∑n≥1n3. These values are sensible, however, as analytic continuations, which correspond to Riemann's ζ-function. Moreover, they have applications in physics: we discuss the vacuum energy of the photon field, from which one can derive the Casimir force, which has been experimentally measured. We also discuss its interpretation, which remains controversial. This is a simple way to illustrate the concept of renormalization, which is vital in quantum field theory.
Comments: 32 pages, LaTex, 6 figures, to appear in Rev. Mex. Fis. E
Subjects: History and Philosophy of Physics (physics.hist-ph); Popular Physics (physics.pop-ph); Quantum Physics (quant-ph)
Cite as: arXiv:2102.09371 [physics.hist-ph]
(or arXiv:2102.09371v1 [physics.hist-ph] for this version)
лошадь, диаграмма, Фейнман

Теория ядерных реакций и протонная терапия

или Сказ о том, как доставка кислорода-18 может повысить эффективность протонной терапии опухолей. Это совершенно обалденная статья на 39 страниц с кучей аппендиксов. Дело в том, что это не обычная характерная для радиобиологии и медицины эмпирика, а физика. С подробной теорией ядерных реакций, с кинематикой, использующей релятивистские инварианты и т.п., с кучей аппендиксов. Просто просится сразу в два моих спецкурса!

Using thymine-18 for enhancing dose delivery and localizing the Bragg peak in proton-beam therapy: https://arxiv.org/abs/2102.09081
William Parke, Dalong Pang
Therapeutic protons acting on O18-substituted thymidine increase cytotoxicity in radio-resistant human cancer cells. We consider here the physics behind the irradiation during proton beam therapy and diagnosis using O18-enriched thymine in DNA, with attention to the effect of the presence of thymine-18 on cancer cell death.