Correlations in a weakly interacting two-dimensional random flow.

We analytically examine fluctuations of vorticity excited by an external random force in two-dimensional fluid. We develop the perturbation theory enabling one to calculate nonlinear corrections to correlation functions of the flow fluctuations found in the linear approximation. We calculate the correction to the pair correlation function and the triple correlation function. It enables us to establish the criterion of validity of the perturbation theory for different ratios of viscosity and bottom friction. We find that the corrections to the second moment are anomalously weak in the cases of small bottom friction and small viscosity and relate the weakness to the energy and enstrophy balances. We demonstrate that at small bottom friction the triple correlation function is characterized by universal scaling behavior in some region of lengths. The developed perturbation method was verified and confirmed by direct numerical simulations.

Coherent vortex in two-dimensional turbulence: Interplay of viscosity and bottom friction.

We examine coherent vortices appearing as a result of the inverse cascade of two-dimensional turbulence in a finite box in the case of pumping with arbitrary correlation time in the quasilinear regime. We demonstrate that the existence of the vortices depends on the ratio between the values of the bottom friction coefficient α and the viscous damping of the flow fluctuations at the pumping scale νk_{f}^{2} (ν is the kinematic viscosity coefficient and k_{f} is the characteristic wave vector at the pumping scale). The coherent vortices appear if νk_{f}^{2}≫α and cannot exist if νk_{f}^{2}≪α. Therefore there is a border value α∼νk_{f}^{2} separating the regions. In numerical simulations, νk_{f}^{2}/α can be arbitrary, whereas in a laboratory experiment νk_{f}^{2}/α≲1 and the coherent vortices can be observed solely near the border value of νk_{f}^{2}/α.

Landau theory for smectic-A-hexatic-B coexistence in smectic films.

We explain theoretical peculiarities of the smectic-A-hexatic-B equilibrium phase coexistence in a finite-temperature range recently observed experimentally in free-standing smectic films [I. A. Zaluzhnyy et al., Phys. Rev. E 98, 052703 (2018)2470-004510.1103/PhysRevE.98.052703]. We quantitatively describe this unexpected phenomenon within Landau phase transitions theory assuming that the film state is close to a tricritical point. We found that the surface hexatic order diminishes the phase coexistence range as the film thickness decreases, shrinking it to zero at some minimal film thickness L_{c}, of the order of a few hexatic correlation length. We established universal laws for the temperature width of the phase coexistence range in terms of the reduced variables. Our theory is in agreement with the existing experimental data.

[Surgical treatment of a patient presenting with an infected aortofemoral bifurcation prosthesis]. / Khirurgicheskoe lechenie bol'nogo s infitsirovannym aorto-bedrennym bifurkatsionnym protezom.

Described herein is a clinical case report regarding successive treatment of a patient presenting with total infection of an aortofemoral bifurcation vascular prosthesis and a purulent fistula in the left iliac-inguinal region. The patient was subjected to removal of the infected aortofemoral bifurcation prosthesis, followed by autovenous aortofemoral bifurcation prosthetic repair. There were no pyo-haemorrhagic complications in the postoperative period. The wounds of the femurs and in the inguinal regions healed with second intention. Check-up computed tomography performed 3 months postoperatively demonstrated satisfactory patency of the autovenous graft and no retroperitoneal formations.

Publisher Correction: Wave kinetics of random fibre lasers.

This corrects the article DOI: 10.1038/ncomms7214.

Effects of thin film and Stokes drift on the generation of vorticity by surface waves.

Recently a theoretical scheme explaining the vorticity generation by surface waves in liquids was developed [Phys. Rev. Lett. 116, 054501 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.054501]. Here we study how a thin (monomolecular) film presented on the surface of liquid affects the generated vorticity. We demonstrate that the vorticity becomes parametrically larger than for the case of liquid with a free surface, and the parameter is the quality factor of surface waves up to numerical factor. We also discuss the PIV experimental scheme intended to observe the generated vorticity and find that Stokes drift influences the measured velocity field. Explicit expression for the vertical vorticity was obtained.

Theory of the anomalous critical behavior for the smectic-A-hexatic transition.

We propose a theoretical explanation for the long-standing problem of the anomalous critical behavior of the heat capacity near the smectic-A-hexatic phase transition. Experiments find a large specific heat critical exponent α=0.5-0.7, which is inconsistent with a small negative value α≈-0.01 expected for the three-dimensional XY universality class. We show that most of the observed features can be explained by treating simultaneously fluctuations of the hexatic orientational and translational (positional) order parameters. Assuming that the translational correlation length ξ_{tr} is much larger than the hexatic correlation length ξ_{h}, we calculate the temperature dependence of the heat capacity in the critical region near the smectic-A-hexatic phase transition. Our results are in quantitative agreement with the calorimetric experimental data.

Structure of coherent vortices generated by the inverse cascade of two-dimensional turbulence in a finite box.

We discuss the structure and geometrical characteristics of coherent vortices appearing as a result of the inverse cascade in two-dimensional turbulence in a finite box. We demonstrate that the universal velocity profile, established by J. Laurie et al. [Phys. Rev. Lett. 113, 254503 (2014)], corresponds to the passive regime of flow fluctuations. We find the vortex core radius and the vortex size, and we argue that the amount of vortices generated in the box depends on the system parameters.

Nonlinear Generation of Vorticity by Surface Waves.

We demonstrate that waves excited on a fluid surface produce local surface rotation owing to hydrodynamic nonlinearity. We examine theoretically the effect and obtain an explicit formula for the vertical vorticity in terms of the surface elevation. Our theoretical predictions are confirmed by measurements of surface motion in a cell with water where surface waves are excited by vertical and harmonic shaking the cell. The experimental data are in good agreement with the theoretical predictions. We discuss physical consequences of the effect.

Nonlinear fluctuation effects in dynamics of freely suspended films.

Long-scale dynamic fluctuation phenomena in freely suspended films is analyzed. We consider isotropic films that, say, can be pulled from bulk smectic-A liquid crystals. The key feature of such objects is possibility of bending deformations of the film. The bending (also known as flexular) mode turns out to be anomalously weakly attenuated. In the harmonic approximation there is no viscous-like damping of the bending mode, proportional to q2 (q is the wave vector of the mode), since it is forbidden by the rotational symmetry. Therefore, the bending mode is strongly affected by nonlinear dynamic fluctuation effects. We calculate the dominant fluctuation contributions to the damping of the bending mode due to its coupling to the inplane viscous mode, which restores the viscous-like q^{2} damping of the bending mode. Our calculations are performed in the framework of the perturbation theory where the coupling of the modes is assumed to be small, then the bending mode damping is relatively weak. We discuss our results in the context of existing experiments and numeric simulations of the freely suspended films and propose possible experimental observations of our predictions.

Wave kinetics of random fibre lasers.

Traditional wave kinetics describes the slow evolution of systems with many degrees of freedom to equilibrium via numerous weak non-linear interactions and fails for very important class of dissipative (active) optical systems with cyclic gain and losses, such as lasers with non-linear intracavity dynamics. Here we introduce a conceptually new class of cyclic wave systems, characterized by non-uniform double-scale dynamics with strong periodic changes of the energy spectrum and slow evolution from cycle to cycle to a statistically steady state. Taking a practically important example-random fibre laser-we show that a model describing such a system is close to integrable non-linear Schrödinger equation and needs a new formalism of wave kinetics, developed here. We derive a non-linear kinetic theory of the laser spectrum, generalizing the seminal linear model of Schawlow and Townes. Experimental results agree with our theory. The work has implications for describing kinetics of cyclical systems beyond photonics.

[The acquired overt cytomegalovirus infection (primary form and reactivation) in adult immune safety patients].

The analysis was applied to clinical course of disease in 102 patients with acquired overt cytomegalovirus infection (75 patients with primary form, 27 patients with reactivation). The primary form of acquired overt cytomegalovirus infection was identified on the basis of detection in enzymoimmunoassay of CMV-lgM under negative CMV-IgG or CMV-IgM and CMV-IgG with avidity less that 50%. The reactivation was diagnosed under identification of CMV-IgG with avidity 50% and more with low indicators of CMV-IgM. The acquired overt cytomegalovirus infection occurs more often in males of young age and proceeds mainly in generalized medium severe form with fever, intoxication and hepatosplenomegaly. The clinical differences are limited by higher rate of generalized forms of disease, febrile fever, weakness, hepatomegaly with increasing of activity of aminotransferase of blood serum, manifestation of signs of affection of respiratory tracts and increase of number of atypical mononuclear leukocytes of peripheral blood in patients with primary form of acquired overt cytomegalovirus infection as compared with reactivated infection.

[Use of infusion solution remaxol in the combination treatment of patients with leptospirosis].

AIM: To evaluate the efficiency of using remaxol in the combination treatment of patients with leptospirosis. SUBJECTS AND METHODS: Thirty patients (29 men and 1 woman) with leptospirosis were treated with remaxol. The icteric and anicteric forms of the disease were diagnosed in 28 and 2 patients, respectively. Moderate, severe, and very severe leptospirosis were observed in 3, 24, and 3 cases, respectively. Remaxol was injected intravenously as a ready-to-use infusion solution 400 ml/day; the treatment duration was 3 to 9 days at the height of the disease. RESULTS: Clinical improvement and normalization of laboratory parameters were achieved in the course of the disease. There were no deaths. During early convalescence at 4-5 weeks of the disease, the patients taking remaxol at the height of the disease were substantially more rarely recorded to have general weakness, fever, anorexia, myalgia, leukocytosis, increased erythrocyte sedimentation rate, and hyperbilirubinemia than those untreated with this drug. CONCLUSION: The performed study established the clinical efficacy of remaxol when used in the combination treatment of patients with leptospirosis.

[Hydrophilic regulator hexapeptides as inhibitors of tumor cell multiple drug resistance].

Multiple drug resistance (MDR) of tumor cells to cytostatics is one of the most often and severe complications of chemotherapy in oncological patients. The phenomenon of MDR could be due to a sharp increase of the activity of the ATP-dependent transport proteins of the ABC system, that provides pumping of the drug from the cells to the extracellular space. Up to now, all the attempts to design agents preventing MDR were of no success. One of the prospective trends is the use of hydrophilic regulator hexapeptides. Three regulator hydrophilic hexapeptides of the linear and cyclic structure were used as the MDR modulators. The sensitivity of the tumor cells to various cytostatics in the presence of the peptides was determined by the MTT-test and the direct counting of the survived cells. The effect of the hexapeptides on MCF7, KB8-5 and PC3 cells was investigated. It was concluded that the hydrophilic hexapeptides of the linear and cyclic structure increased the sensitivity to doxorubicin (a cytostatic). The tumor cell MDR inhibition was mediated by the ATP-dependent transport protein MRP. Such a characteristic of the hexapeptides is of interest for their use as agents preventing MDR.

[The results of a multicenter trial of acute lymphoblastic leukemia treatment on ALL-MB 91/ALL-BFM 90m in children: analysis of efficacy and toxicity].

AIM: A comparative analysis of efficacy and toxicity of two chemotherapy regimens: standard German protocol ALL-BFM 90m and less intensive original test protocol ALL-MB 91 in a multicenter trial of acute lymphoblastic leukemia (ALL) in children. MATERIAL AND METHODS: In 1995-2002 a total of 834 patients with newly diagnosed ALL aged 0-18 years were admitted to 10 clinics of Russia. Of them, 713 were randomized in two groups: treatment program ALL-BFM 90m (n = 355) and ALL-MB 91 program (n = 358). RESULTS: In 7-year follow-up median, 10-year event-free survival (EFS) and overall survival (OS) did not differ significantly between the groups and was 67 +/- 3 and 68 +/- 3% (ALL-MB 91) and 74 +/- 2, 71 +/- 3% (ALL-BFM 90m), respectively. Though the rate of isolated recurrences in CNS in patients on the protocol ALL-MB 91 was 2.8%, they developed only in 0.8% patients of the standard risk group. Anemia, thrombocytopenia and agranulocytosis developed less frequently, hospital stay was significantly shorter on the test protocol vs the control one (p < 0.01). CONCLUSION: EFS and OS on the test (ALL-MB 91) and control (ALL-BFM 90m) protocols were equivalent in lower toxicity and cost of therapy.

Dynamics of nearly spherical vesicles in an external flow.

Tank-treading, tumbling, and trembling are different types of the vesicle behavior in an external flow. We derive a dynamical equation enabling us to establish a state of nearly spherical vesicles. For a 2D external flow, the character of the vesicle dynamics is determined by two dimensionless parameters, depending on the vesicle excess area, fluid viscosities, membrane viscosity and bending modulus, strength of the flow, and ratio of the elongational and rotational components of the flow. The tank-treading to tumbling transition occurs via a saddle-node bifurcation, whereas the tank-treading to trembling transition occurs via a Hopf bifurcation. A slowdown of vesicle dynamics should be observed in a vicinity of a point separating the transition lines. We show that the slowdown can be described by a power law with two different critical exponents 1/4 and 1/2 corresponding to the slowdown of tumbling and trembling cycles.

[The peculiarities of plantar pressure distribution during gait in different variants of functional system impairment in patients with multiple sclerosis].

Gait disturbance is a prominent disabling presentation of multiple sclerosis. The data on the distribution of plantar pressure during gait and its relation to the level of neurological deficit in various disturbances of pyramidal and cerebral functions in remitting type of multiple sclerosis are presented.