Suppression of stimulated Brillouin scattering in optical fibers using a linearly chirped diode laser

The output of high power fiber amplifiers is typically limited by stimulated Brillouin scattering (SBS). An analysis of SBS with a chirped pump laser indicates that a chirp of 2.5 × 10^(15) Hz/s could raise, by an order of magnitude, the SBS threshold of a 20-m fiber. A diode laser with a constant output power and a linear chirp of 5 × 10^(15) Hz/s has been previously demonstrated. In a low-power proof-of-concept experiment, the threshold for SBS in a 6-km fiber is increased by a factor of 100 with a chirp of 5 × 10^(14) Hz/s. A linear chirp will enable straightforward coherent combination of multiple fiber amplifiers, with electronic compensation of path length differences on the order of 0.2 m

Properties of the solvation force of a two-dimensional Ising strip in scaling regimes

We consider d=2 Ising strip with surface fields acting on boundary spins. Using the properties of the transfer matrix spectrum we identify two pseudotransition temperatures and show that they satisfy similar scaling relations as expected for real transition temperatures in strips with d>2. The solvation force between the boundaries of the strip is analysed as a function of temperature, surface fields and the width of the strip. For large widths the solvation force can be described by scaling functions in three different regimes: in the vicinity of the critical wetting temperature of 2D semi-infinite system, in the vicinity of the bulk critical temperature, and in the regime of weak surface fields where the critical wetting temperature tends towards the bulk critical temperature. The properties of the relevant scaling functions are discussed

Critical energy-density profile near walls

We examine critical adsorption for semi-infinite thermodynamic systems of the Ising universality class when they are in contact with a wall of the so-called normal surface universality class in spatial dimension d=3 and in the mean-field limit. We apply local-functional theory and Monte Carlo simulations in order to quantitatively determine the properties of the energy density as the primary scaling density characterizing the critical behaviors of Ising systems besides the order parameter. Our results apply to the critical isochore, near two-phase coexistence, and along the critical isotherm if the surface and the weak bulk magnetic fields are either collinear or anticollinear. In the latter case, we also consider the order parameter, which so far has yet to be examined along these lines. We find the interface between the surface and the bulk phases at macroscopic distances from the surface, i.e., the surface is “wet.” It turns out that in this case the usual property of monotonicity of primary scaling densities with respect to the temperature or magnetic field scaling variable does not hold for the energy density due to the presence of this interface

How long does it take to pull an ideal polymer into a small hole?

We present scaling estimates for characteristic times $\tau_{\rm lin}$ and $\tau_{\rm br}$ of pulling ideal linear and randomly branched polymers of $N$ monomers into a small hole by a force $f$. We show that the absorbtion process develops as sequential straightening of folds of the initial polymer configuration. By estimating the typical size of the fold involved into the motion, we arrive at the following predictions: $\tau_{\rm lin}(N) \sim N^{3/2}/f$ and $\tau_{\rm br}(N) \sim N^{5/4}/f$, and we also confirm them by the molecular dynamics experiment.Comment: 4 pages, 3 figure

Universal scaling functions of critical Casimir forces obtained by Monte Carlo simulations

Effective Casimir forces induced by thermal fluctuations in the vicinity of bulk critical points are studied by means of Monte Carlo simulations in three-dimensional systems for film geometries and within the experimentally relevant Ising and XY universality classes. Several surface universality classes of the confining surfaces are considered, some of which are relevant for recent experiments. A novel approach introduced previously EPL 80, 60009 (2007), based inter alia on an integration scheme of free energy differences, is utilized to compute the universal scaling functions of the critical Casimir forces in the critical range of temperatures above and below the bulk critical temperature. The resulting predictions are compared with corresponding experimental data for wetting films of fluids and with available theoretical results.Comment: 21 pages, 17 figure

Morphological changes in testicles of patients with idiopathic infertility after novel coronavirus infection (COVID-19)

Introduction. SARS-CoV-2 causes several negative processes in the body and complicates the course of chronic somatic diseases, causing dysfunction and having a negative effect on many organs and systems of the body, including organs of the reproductive system.Objective. To study morphological changes in testicles of patients who have undergone a new coronavirus infection.Materials and methods. Objects of morphological research were testicular tissues obtained by intraoperative biopsy under intravenous anesthesia served. Material sampling was carried out in 12 patients aged 25–29 years with idiopathic infertility who underwent COVID-19. Patients showed ultrasound signs of fibrosis in the testicles, which were absent before infection with SARS-CoV-2. The biopsy was performed 12 months after COVID-19.Results. In all observations, changes were observed that are characteristic of the inflammatory process, nonbacterial autoimmune genesis. Histio-lymphocytic infiltration of testicular tissue with destruction of single tubules and parenchyma atrophy, combined with varying degrees of sclerosis, was verified.Conclusion. In testicular biopsy specimens from patients who have undergone COVID-19, an autoimmune inflammatory process is recorded, manifested by lymphocytic infiltration of testicular tissue, which was combined with varying degrees of sclerosis

СРАВНИТЕЛЬНЫЙ АНАЛИЗ РЕЗУЛЬТАТОВ РАДИКАЛЬНОЙ ЦИСТЭКТОМИИ И КИШЕЧНОЙ ДЕРИВАЦИИ МОЧИ ПРИ ВЫПОЛНЕНИИ МЕЖКИШЕЧНЫХ АНАСТОМОЗОВ АППАРАТНЫМ И РУЧНЫМ ШВОМ

The results of treatment were analyzed in 53 patients with high-risk non-muscle invasive bladder cancer (BC), who had undergone radical cystectomy (RCE) and bilateral pelvic lymphadenectomy. Histological hypostaging was noted in 20.7% of the patients; 13.2% of them had regional lymph node metastases, which confirms the problems associated with the accurate determination of a BC stage in clinical stage T1. The predictors of lower cancer-specific survival were identified in patients after RCE for pT1 cancer. In our study, 5- and 10-year cancer-specific survival was 90.5 and 88.6% in cT1 stage and 98.2 and 96.3% in pT1 stage, respectively. The findings strongly suggest that RCE can afford a long-term high cancer-specific survival in patients with non-muscle invasive BC.Проведен анализ результатов лечения 240 пациентов с раком мочевого пузыря (РМП) путем выполнения радикальной цистэктомии (РЦЭ) с кишечной деривацией мочи за период с 1995 по 2010 г. Из них 75 (31,2 %) больным (1-я группа) выполнен межкишечный анастомоз посредством ручного шва, а 165 (68,8 %) больным (2-я группа) — аппаратный межкишечный анастомоз. Послеоперационная летальность в 1-й группе оказалась достоверно выше: 14,6 % против 2,4 % во 2-й группе. В группе больных с ручным межкишечным анастомозом отмечено и большее количество ранних послеоперационных осложнений (РПО) — 22,6 % — при большей длительности операции (6,3 ч) по сравнению с пациентами с аппаратным межкишечным анастомозом, потребовавшим меньше времени для выполнения — до 4,7 ч, и имевших меньше РПО — до 9,0 %. При этом в 1-й группе осложнения выявлены у 75 % пациентов с коморбидностью, а во 2-й — у 40,6 %. С учетом этого можно говорить о большем риске развития РПО у больных с ручным межкишечным анастомозом. В 1-й группе больных 5-летняя общая выживаемость составила всего 17 %, тогда как во 2-й — 80 %. Таким образом, даже при наличии сопутствующих заболеваний при применении сшивающих аппаратов для выполнения межкишечных анастомозов удается значительно снизить количество РПО, сократить продолжительность операции, повысить ее безопасность и тем самым увеличить общую выживаемость пациентов

РЕТРОСПЕКТИВНЫЙ АНАЛИЗ РЕЗУЛЬТАТОВ РАДИКАЛЬНОЙ ЦИСТЭКТОМИИ ПРИ НЕМЫШЕЧНО-ИНВАЗИВНОМ РАКЕ МОЧЕВОГО ПУЗЫРЯ

The results of treatment were analyzed in 53 patients with high-risk non-muscle invasive bladder cancer (BC), who had undergone radical cystectomy (RCE) and bilateral pelvic lymphadenectomy. Histological hypostaging was noted in 20.7% of the patients; 13.2% of them had regional lymph node metastases, which confirms the problems associated with the accurate determination of a BC stage in clinical stage T1. The predictors of lower cancer-specific survival were identified in patients after RCE for pT1 cancer. In our study, 5- and 10-year cancerspecific survival was 90.5 and 88.6% in cT1 stage and 98.2 and 96.3% in pT1 stage, respectively. The findings strongly suggest that RCE can afford a long-term high cancer-specific survival in patients with non-muscle invasive BC.Проведен анализ результатов лечения 53 пациентов с клинически немышечно-инвазивным раком мочевого пузыря (РМП) высокого риска, подвергнутых радикальной цистэктомии (РЦЭ) и двусторонней тазовой лимфаденэктомии. Гистологическое гипостадирование отмечено у 20,7 % пациентов, причем 13,2 % из них имели метастазы в регионарные лимфатические узлы, что подтверждает трудности, связанные с точностью установки стадии РМП при клинической стадии Т1. Определены факторы прогноза сниженной канцерспецифической выживаемости у больных после РЦЭ при рТ1. В нашем исследовании показатели 5- и 10-летней канцерспецифической выживаемости составили 90,5 и 88,6 % при сТ1 и 98,2 и 96,3 % при рТ1. Данные результаты убедительно свидетельствуют о возможности обеспечения методом РЦЭ долговременной высокой канцерспецифической выживаемости больных немышечно-инвазивным РМП