Gravitational Solitons and Monodromy Transform Approach to Solution of Integrable Reductions of Einstein Equations

In this paper the well known Belinskii and Zakharov soliton generating transformations of the solution space of vacuum Einstein equations with two-dimensional Abelian groups of isometries are considered in the context of the so called "monodromy transform approach", which provides some general base for the study of various integrable space - time symmetry reductions of Einstein equations. Similarly to the scattering data used in the known spectral transform, in this approach the monodromy data for solution of associated linear system characterize completely any solution of the reduced Einstein equations, and many physical and geometrical properties of the solutions can be expressed directly in terms of the analytical structure on the spectral plane of the corresponding monodromy data functions. The Belinskii and Zakharov vacuum soliton generating transformations can be expressed in explicit form (without specification of the background solution) as simple (linear-fractional) transformations of the corresponding monodromy data functions with coefficients, polynomial in spectral parameter. This allows to determine many physical parameters of the generating soliton solutions without (or before) calculation of all components of the solutions. The similar characterization for electrovacuum soliton generating transformations is also presented.Comment: 8 pages, 1 figure, LaTeX2e; based on a talk given at the International Conference 'Solitons, Collapses and Turbulence: Achievements, Developments and Perspectives', (Landau Institute for Theoretical Physics, Chernogolovka, Moscow region, Russia, August 3 -- 10, 1999); as submitted to Physica

The stability of Killing-Cauchy horizons in colliding plane wave space-times

It is confirmed rigorously that the Killing-Cauchy horizons, which sometimes occur in space-times representing the collision and subsequent interaction of plane gravitational waves in a Minkowski background, are unstable with respect to bounded perturbations of the initial waves, at least for the case in which the initial waves have constant aligned polarizations.Comment: 8 pages. To appear in Gen. Rel. Gra

Диагностика глубокой перипротезной инфекции тазобедренного сустава

Periprosthetic infection (PJI) is one of the most frequent and devastating complications of total hip arthroplasty (THA). Early and accurate diagnosis of PJI allows timely initiation of treatment. Various diagnostic tools and algorithms for hip PJI diagnosis are described. The available serum (ESR, CRP, D-dimer, etc.) and synovial (alpha-defensin, leukocyte esterase, D-lactate) biomarkers are listed, as well as their combinations for the purpose of PJI verification. Combined serum and synovial tests can significantly improve the efficiency of PJI hip diagnosis.Перипротезная инфекция (ППИ) является одним из наиболее частых и разрушительных осложнений эндопротезирования тазобедренного сустава (ТБС). Ранняя и точная диагностика ППИ позволяет своевременно начать лечение. Описаны различные диагностические инструменты и алгоритмы диагностики ППИ ТБС. Перечислены имеющиеся сывороточные (СОЭ, СРБ, D-димер и др.) и синовиальные (альфа-дефенсин, лейкоцитарная эстераза, D-лактат) биомаркеры, а также их комбинации с целью верификации ППИ. Объединение сывороточных и синовиальных тестов позволяет значительно повысить эффективность диагностики ППИ ТБС

Ранние результаты одномыщелкового эндопротезирования медиального отдела коленного сустава

Background. Among the methods of surgical treatment of early stages medial knee osteoarthritis in the partial knee replacement (PKR) becomes more and more relevant. The relevance and increasing number of PKR are confirmed by data from various national registers.The aim of the study was to research the early functional results of PKR and to analyze the complications at various stages of the postoperative period.Material and Methods. Study design: a single-center prospective study. The results of 90 operations of PKR in the period from March 2018 to April 2020 are presented. Assessment of knee function and quality of life of patients was performed according to three scalesquestionnaires: KOOS, WOMAC, SF-36, which were filled in preoperatively and then at 3, 6, 9, 12, 18 months. after surgery. Patients within the reporting period provided X-rays and filled in the scales at the face-to-face examination and at remote contact.Results. The most significant improvement of quality of life and median values of the functional results observed after 3 months, and after 18 months. After replacement the best median functional outcome scales KOOS, WOMAC, SF-36 — 79,4 (73,6–84,3); 27,1 (24,8–30,6); 89,1 (85,3–92,6) compared with the functional results obtained before surgery 32,3 (22,8–38,4); 73,6 (63,6–78,8); 35,2 (31,3–42,1); p = 0,027; p = 0.023; p = 0,028, respectively. A negative correlation was obtained between BMI and functional outcome (p = 0.027, R = -0.7).Conclusion. PKR allowed us to achieve an improvement in the quality of life and functional results already in the early postoperative period (from 3 to 18 months after the operation). The improvement of the operating technique, the analysis of errors and the regularity of the performed PKR will improve the results of PKR and minimize the number of complications.Актуальность. Среди методов хирургического лечения ранних стадий медиального гонартроза все чаще используется одномыщелковое эндопротезирование коленного сустава (ОЭКС). Постоянно увеличивающееся число выполняемых ОЭКС медиального отдела подтверждается данными различных национальных регистров артропластики.Цель исследования — оценить ранние функциональные результаты одномыщелкового эндопротезирования медиального отдела коленного сустава и проанализировать осложнения на различных этапах послеоперационного периода.Материал и методы. Дизайн исследования: одноцентровое проспективное. Представлены результаты 90 операций ОЭКС медиального отдела в период с марта 2018 по апрель 2020 г. Оценку функции коленного сустава и качества жизни пациентов проводили с использованием шкал-опросников: KOOS, WOMAC, SF-36 до операции и через 3, 6, 9, 12, 18 мес. после ее выполнения. Оценку функционального состояния пациентов по KOOS и WOMAC высчитывали в процентах от максимально возможной суммы баллов по каждой из шкал.Результаты. Наиболее значимое улучшение качества жизни и функционального состояния зарегистрировано через 3 мес., а через 18 мес. после эндопротезирования получены наилучшие результаты: KOOS — 79,4% (73,6–84,3); WOMAC — 27,1% (24,8–30,6); SF-36 — 89,1 баллов (85,3–92,6) по сравнению состоянием до операции 32,3% (22,8–38,4) р = 0,027; 73,6% (63,6–78,8) р = 0,023; 35,2 баллов (31,3–42,1) р = 0,028 соответственно. Получена отрицательная корреляция между ИМТ и функциональным исходом (р = 0,027, R = -0,7). В послеоперационном периоде выявлены осложнения у 8 пациентов, из которых 3 пациентам выполнено ревизионное оперативное вмешательство, а 5 — проводилось консервативное лечение.Заключение. ОЭКС медиального отдела позволяет добиться улучшения качества жизни и функционального состояния уже на ранних сроках (от 3 до 18 мес.) после операции. Совершенствование операционной техники, анализ ошибок и регулярное выполнение хирургом операций ОЭКС позволят улучшить результаты и минимизировать количество осложнений

Effective Functional Form of Regge Trajectories

We present theoretical arguments and strong phenomenological evidence that hadronic Regge trajectories are essentially nonlinear and can be well approximated, for phenomenological purposes, by a specific square-root form.Comment: 29 pages, LaTeX. Published versio

Dressing with Control: using integrability to generate desired solutions to Einstein's equations

21 pages, no figures21 pages, no figures21 pages, no figures21 pages, no figuresMotivated by integrability of the sine-Gordon equation, we investigate a technique for constructing desired solutions to Einstein's equations by combining a dressing technique with a control-theory approach. After reviewing classical integrability, we recall two well-known Killing field reductions of Einstein's equations, unify them using a harmonic map formulation, and state two results on the integrability of the equations and solvability of the dressing system. The resulting algorithm is then combined with an asymptotic analysis to produce constraints on the degrees of freedom arising in the solution-generation mechanism. The approach is carried out explicitly for the Einstein vacuum equations. Applications of the technique to other geometric field theories are also discussed

3D heterotic string theory: new approach and extremal solutions

We develop a new formalism for the bosonic sector of low-energy heterotic string theory toroidally compactified to three dimensions. This formalism is based on the use of some single non-quadratic real matrix potential which transforms linearly under the action of subgroup of the three-dimensional charging symmetries. We formulate a new charging symmetry invariant approach for the symmetry generation and straightforward construction of asymptotically flat solutions. Finally, using the developed approach and the established formal analogy between the heterotic and Einstein-Maxwell theories, we construct a general class of the heterotic string theory extremal solutions of the Israel-Wilson-Perjes type. This class is asymptotically flat and charging symmetry complete; it includes the extremal solutions constructed before and possesses the non-trivial bosonic string theory limit.Comment: 20 pages in Late

General boundary conditions for the envelope function in multiband k.p model

We have derived general boundary conditions (BC) for the multiband envelope functions (which do not contain spurious solutions) in semiconductor heterostructures with abrupt heterointerfaces. These BC require the conservation of the probability flux density normal to the interface and guarantee that the multiband Hamiltonian be self--adjoint. The BC are energy independent and are characteristic properties of the interface. Calculations have been performed of the effect of the general BC on the electron energy levels in a potential well with infinite potential barriers using a coupled two band model. The connection with other approaches to determining BC for the envelope function and to the spurious solution problem in the multiband k.p model are discussed.Comment: 15 pages, 2 figures; to be published in Phys. Rev. B 65, March 15 issue 200

Transverse Momentum Dependent Parton Distribution/Fragmentation Functions at an Electron-Ion Collider

We present a summary of a recent workshop held at Duke University on Partonic Transverse Momentum in Hadrons: Quark Spin-Orbit Correlations and Quark-Gluon Interactions. The transverse momentum dependent parton distribution functions (TMDs), parton-to-hadron fragmentation functions, and multi-parton correlation functions, were discussed extensively at the Duke workshop. In this paper, we summarize first the theoretical issues concerning the study of partonic structure of hadrons at a future electron-ion collider (EIC) with emphasis on the TMDs. We then present simulation results on experimental studies of TMDs through measurements of single spin asymmetries (SSA) from semi-inclusive deep-inelastic scattering (SIDIS) processes with an EIC, and discuss the requirement of the detector for SIDIS measurements. The dynamics of parton correlations in the nucleon is further explored via a study of SSA in D (`D) production at large transverse momenta with the aim of accessing the unexplored tri-gluon correlation functions. The workshop participants identified the SSA measurements in SIDIS as a golden program to study TMDs in both the sea and valence quark regions and to study the role of gluons, with the Sivers asymmetry measurements as examples. Such measurements will lead to major advancement in our understanding of TMDs in the valence quark region, and more importantly also allow for the investigation of TMDs in the sea quark region along with a study of their evolution.Comment: 44 pages 23 figures, summary of Duke EIC workshop on TMDs accepted by EPJ

Search for composite and exotic fermions at LEP 2

A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio