On quantization of singular varieties and applications to D-branes

We calculate the ring of differential operators on some singular affine varieties (intersecting stacks, a point on a singular curve or an orbifold). Our results support the proposed connection of the ring of differential operators with geometry of D-branes in (bosonic) string theory. In particular, the answer does know about the resolution of singularities in accordance with the string theory predictions.Comment: LaTeX2e, 17 pages, misprints correcte

Screw dynamo in a time-dependent pipe flow

The kinematic dynamo problem is investigated for the flow of a conducting fluid in a cylindrical, periodic tube with conducting walls. The methods used are an eigenvalue analysis of the steady regime, and the three-dimensional solution of the time-dependent induction equation. The configuration and parameters considered here are close to those of a dynamo experiment planned in Perm, which will use a torus-shaped channel. We find growth of an initial magnetic field by more than 3 orders of magnitude. Marked field growth can be obtained if the braking time is less than 0.2 s and only one diverter is used in the channel. The structure of the seed field has a strong impact on the field amplification factor. The generation properties can be improved by adding ferromagnetic particles to the fluid in order to increase its relative permeability,but this will not be necessary for the success of the dynamo experiment. For higher magnetic Reynolds numbers, the nontrivial evolution of different magnetic modes limits the value of simple `optimistic' and `pessimistic' estimates.Comment: 10 pages, 12 figure

КЛИНИКО-РЕНТГЕНОЛОГИЧЕСКИЕ ОСОБЕННОСТИ ФОРМИРОВАНИЯ ДИСТРАКЦИОННОГО РЕГЕНЕРАТА ПРИ УДЛИНЕНИИ ГОЛЕНИ ПО ИЛИЗАРОВУ

The article presents results of surgical elongation of 999 shins in 572 patients by the Ilizarov apparatus. The main attention is paid to the x-ray features of the distraction regenerate formation with elongation of the tibia in the proximal part. There are possible three types of regenerate formation: normotrophic, hypotrophic, hypertrophic. The main problems associated with the features of regeneration and possible ways of their correction are presented. The description of the picture of the gradual regenerate formation at various times during the stages of distraction and fixation is presented. The radiographic signs are described in detail, which allow us to conclude that the external fixator can be removed. This is the density of the regenerate. The presented material is of interest to orthopedists, radiologists and medical experts.В статье представлен анализ результатов хирургического удлинения 999 голеней у 572 пациентов с помощью аппарата Илизарова. Основное внимание уделено рентгенологическим особенностям формирования дистракционного регенерата при удлинении большеберцовой кости в проксимальном отделе. Рассматриваются признаки, позволяющие отнести регенерат к одному из трех типов: нормотрофический, гипотрофический, гипертрофический. Представлены основные проблемы, связанные с особенностями регенерации и возможные пути их коррекции. Представлено описание картины постепенного формирования регенерата в различные сроки на этапах дистракции и фиксации. Подробно описываются рентгенологические признаки, которые позволяют сделать заключение о возможности снятия внешнего фиксатора. Таким признаком является плотность регенерата. Представленный материал представляют интерес для травматологов-ортопедов, рентгенологов и врачей-экспертов

Features of surgical treatment of posttraumatic lower limbs of different lengths in adult patients

Relevance Different lengths of the lower extremities have a negative impact on the position of the pelvis and spine and lead to secondary deformities. To prevent these consequences, early surgical correction of the shortening is necessary. Aim of study Study of the features of post-traumatic shortening of the lower extremities, mechanisms of adaptation to this condition and, on the basis of this, optimization of surgical technique when performing reconstructive and restorative operations. Material and methods A total of 276 patients with posttraumatic shortening of the lower extremities were examined, 102 of whom were operated on. Comparative radiography of both legs was used to diagnose different lengths. The Ilizarov method was used as the main method of surgical correction. Results We studied the mechanisms of adaptation of patients to post-traumatic shortening of the hip and lower leg and optimized surgical technique. A method was developed for determining the optimal elongation value. Conclusion The most effective and least traumatic method is external osteosynthesis according to Ilizarov. Distraction in the apparatus allows the formation of a regenerate of the required shape and length and the elongation of exactly the amount that is optimal for a given patient. © 2020 Sklifosovsky Research Institute for Emergency Medicine. All rights reserved

Method of reducing protein load on beer wort by applying electrocoagulation and ultrasound processes

Beer, like any other food product, has a limited shelf life. Depending on the processes that degrade the quality of beer, there are biological, colloidal, and taste stability of beer. The article describes experimental work aimed at reducing the protein load on beer wort and increasing the resistance of finished beer through the use of electrocoagulation and ultrasound. It is noted that when exposed to electric current and ultrasound on beer wort, there is a decrease in the mass fraction of protein with an increase in the amount of sediment in the studied samples of unshopped beer wort, which confirms the prospects of using these technological methods for processing unshopped beer wort in order to reduce the protein load in beer.Пиво, как и любой другой пищевой продукт, имеет ограниченный срок хранения. В зависимости от процессов, ухудшающих качество пива, выделяют биологическую, коллоидную, вкусовую стойкость пива. В статье описано проведение экспериментальных работ, направленных на снижение белковой нагрузки на пивное сусло и повышение стойкости готового пива посредством использования электрокоагуляции и ультразвука. Отмечено, что при воздействии электрическим током и ультразвуком на пивное сусло, наблюдается снижение массовой доли белка при росте количества осадка в исследуемых образцах неохмеленного пивного сусла, что подтверждает перспективность применения данных технологических приемов обработки неохмеленного пивного сусла с целью снижения белковой нагрузки в пиве