Infl uence of orthostatic test on the heart pumping function in athletes with lower extremities motor disorders

Objective: to study the response of heart pumping function (HPF) of athletes with disabilities to an orthostatic test. Materials and methods: 20 wheelchair athletes (21-30 year-old) were examined. Group I are wheelchair basketball players with amputated lower limbs at the level of the upper third of the tibia. II group - athletes with spinal damage and atrophy of lower limbs at the level of Th 12, L1, with compression, partial rupture of spinal cord, lower limbs paralysis, and small pelvic organ functional disorder. We compared the heart rate (HR) and stroke volume (SV). Th e analysis was carried out in two stages: we take measurements in the lying position and within 5 - 20 seconds aft er an active transition from the lying position to the sitting position. Results: In group I, the HR in the lying position was 77.2±1.4 bpm. With the active change of position, the HR increased by 7.3±1.2 bpm (p<0.05) to 84.5±1.8 bpm. Th e HR in group II in the lying position was 71.3±1.8 bpm. Aft er an active position change, it increased to 75.7±2.1 bpm. Th e HR response to the change of body position in group II was 4.4±1.6 bpm (p<0.05), which was 2.9±1.3 bpm less than the HR response to a change of body position in group I (p<0.05). HR decrease within 4 to 12 bpm may indicate a reduced tone of sympathetic part of vegetative nervous system. Th e SV of group I in the lying position was 54.3±1.6 ml. Aft er active transition from lying position to sitting position, the SV decreased to 45.7±1.9 ml (p<0.05). At transition from lying position to sitting position, the SV reaction in athletes with amputated of lower limbs was 8.6±1.4 ml (p<0.05). In wheelchair basketball players with lower limb atrophy, the SV in lying position was 6.8±1.9 ml and decreased by 4,3±1.7 ml at active transition from lying position to sitting position to 57.5±2.1 ml (p<0.05), which diff ers signifi cantly from the reaction of group I by 4.3±1.6 ml (p<0.05). Conclusions: In group I, the diff erence in HR values in an orthostatic test is signifi cantly higher than in group II

Continuous Synthesis of Hydrogenated Graphene in Thermal Plasma

© 2018, Pleiades Publishing, Ltd. A single-stage catalyst free synthesis of hydrogenated graphene was studied in the process of methane conversion in a helium plasma jet created by a plasma torch at the power up to 45 kW and the pressure of 710 Torr. The synthesis products were studied by the methods of scanning and transmission electron microscopy, thermal analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analysis

Biofriendly nanocomposite containers with inhibition properties for the protection of metallic surfaces

© 2017 The Author(s) Published by the Royal Society. All rights reserved.An attempt to combine two 'green' compounds in nanocomposite microcontainers in order to increase protection properties of waterborne acryl-styrene copolymer (ASC) coatings has been made. Nlauroylsarcosine (NLS) served as a corrosion inhibitor, and linseed oil (LO) as a carrier-forming component. LO is compatible with this copolymer and can impart to the coating self-healing properties. For the evaluation of the protective performance, three types of coatings were compared. In the first two, NLS was introduced in the coating formulation in the forms of free powder and micro-containers filled with LO, correspondingly. The last one was a standard ASC coating without inhibitor at all. Low-carbon steel substrates were coated by these formulations by spraying and subjected subsequently to the neutral salt spray test according to DIN ISO 9227. Results of these tests as well as the data obtained by electrochemical study suggest that such containers can be used for the improvement of adhesion of ASC-based coatings to the substrate and for the enhancement of their protective performance upon integrity damage, whereas the barrier properties of intact coatings were decreased

Self-trapping of strong electromagnetic beams in relativistic plasmas

Interaction of an intense electromagnetic (EM) beam with hot relativistic plasma is investigated. It is shown that the thermal pressure brings about a fundamental change in the dynamics - localized, high amplitude, EM field structures, not accessible to a cold (but relativisic) plasma, can now be formed under well- defined conditions. Examples of the trapping of EM beams in self-guiding regimes to form stable 2D solitonic structures in a pure e-p plasma are worked out.Comment: 9 pages, 6 figure

Stability and collisions of moving semi-gap solitons in Bragg cross-gratings

We report results of a systematic study of one-dimensional four-wave moving solitons in a recently proposed model of the Bragg cross-grating in planar optical waveguides with the Kerr nonlinearity; the same model applies to a fiber Bragg grating (BG) carrying two polarizations of light. We concentrate on the case when the system's spectrum contains no true bandgap, but only semi-gaps (which are gaps only with respect to one branch of the dispersion relation), that nevertheless support soliton families. Solely zero-velocity solitons were previously studied in this system, while current experiments cannot generate solitons with the velocity smaller than half the maximum group velocity. We find the semi-gaps for the moving solitons in an analytical form, and demonstrated that they are completely filled with (numerically found) solitons. Stability of the moving solitons is identified in direct simulations. The stability region strongly depends on the frustration parameter, which controls the difference of the present system from the usual model for the single BG. A completely new situation is possible, when the velocity interval for stable solitons is limited not only from above, but also from below. Collisions between stable solitons may be both elastic and strongly inelastic. Close to their instability border, the solitons collide elastically only if their velocities c1 and c2 are small; however, collisions between more robust solitons are elastic in a strip around c1=-c2.Comment: 16 pages, 7 figures, Physics Letters A, in pres

Analytic theory of narrow lattice solitons

The profiles of narrow lattice solitons are calculated analytically using perturbation analysis. A stability analysis shows that solitons centered at a lattice (potential) maximum are unstable, as they drift toward the nearest lattice minimum. This instability can, however, be so weak that the soliton is ``mathematically unstable'' but ``physically stable''. Stability of solitons centered at a lattice minimum depends on the dimension of the problem and on the nonlinearity. In the subcritical and supercritical cases, the lattice does not affect the stability, leaving the solitons stable and unstable, respectively. In contrast, in the critical case (e.g., a cubic nonlinearity in two transverse dimensions), the lattice stabilizes the (previously unstable) solitons. The stability in this case can be so weak, however, that the soliton is ``mathematically stable'' but ``physically unstable''

Spatiotemporally localized solitons in resonantly absorbing Bragg reflectors

We predict the existence of spatiotemporal solitons (``light bullets'') in two-dimensional self-induced transparency media embedded in a Bragg grating. The "bullets" are found in an approximate analytical form, their stability being confirmed by direct simulations. These findings suggest new possibilities for signal transmission control and self-trapping of light.Comment: RevTex, 3 pages, 2 figures, to be published in PR

Loss of superfluidity in the Bose-Einstein condensate in an optical lattice with cubic and quintic nonlinearity

In a one-dimensional shallow optical lattice, in the presence of both cubic and quintic nonlinearity, a superfluid density wave is identified in a Bose-Einstein condensate. Interestingly, it ceases to exist when only one of these interactions is operative. We predict the loss of superfluidity through a classical dynamical phase transition, where modulational instability leads to the loss of phase coherence. In a certain parameter domain, the competition between lattice potential and the interactions is shown to give rise to a stripe phase, where atoms are confined in finite domains. In a pure two-body case, apart from the known superfluid and insulating phases, a density wave insulating phase is found to exist, possessing two frequency modulations commensurate with the lattice potential.Comment: 5 pages, 1 figur