Characteristics of the electric field accompanying a longitudinal acoustic wave in a metal. Anomaly in the superconducting phase

The temperature dependence of the amplitude and phase of the electric potential arising at a plane boundary of a conductor when a longitudinal acoustic wave is incident normally on it is investigated theoretically and experimentally. The surface potential is formed by two contributions, one of which is spatially periodic inside the sample, with the period of the acoustic field; the second is aperiodic and arises as a result of an additional nonuniformity of the electron distribution in a surface layer of the metal. In the nonlocal region the second contribution is dominant. The phases of these contributions are shifted by approximately \pi /2. For metals in the normal state the experiment is in qualitative agreement with the theory. The superconducting transition is accompanied by catastrophically rapid vanishing of the electric potential, in sharp contrast to the theoretical estimates, which predict behavior similar to the BCS dependence of the attenuation coefficient for a longitudinal sound.Comment: 9 pages, 6 figure

Charge ordering and interlayer phase coherence in quantum Hall superlattices

The possibility of the existence of states with a spontaneous interlayer phase coherence in multilayer electron systems in a high perpendicular to the layers magnetic field is investigated. It is shown that phase coherence can be established in such systems only within individual pairs of adjacent layers, while such coherence does not exist between layers of different pairs. The conditions for stability of the state with interlayer phase coherence against transition to a charge-ordered state are determined. It is shown that in the system with the number of layers N\leq 10 these conditions are satisfied at any value of the interlayer distance d. For N>10 there are two intervals of stability: at sufficiently large and at sufficiently small d. For N\to \infty the stability interval in the region of small d vanishesComment: 10 page

Drag of superfluid current in bilayer Bose systems

An effect of nondissipative drag of a superfluid flow in a system of two Bose gases confined in two parallel quasi two-dimensional traps is studied. Using an approach based on introduction of density and phase operators we compute the drag current at zero and finite temperatures for arbitrary ratio of densities of the particles in the adjacent layers. We demonstrate that in a system of two ring-shape traps the "drag force" influences on the drag trap in the same way as an external magnetic flux influences on a superconducting ring. It allows to use the drag effect to control persistent current states in superfluids and opens a possibility for implementing a Bose analog of the superconducting Josephson flux qubit.Comment: 12 pages, 2 figures, new section is added, refs are adde

Possibilities of telemedicine in work to improve survival in multiple trauma victims

Background: World experience in providing medical assistance to victims of trauma indicates high efficiency of telemedicine methods in organization of medical care to trauma victims and an effective and adequate implementation of therapeutic and diagnostic measures. Material and methods: We made some analyses of the necessity of the telemedicine consultation and control in 1150 patients with multisystem injuries which assisted 1000 victims in the medical institutions of the second level and 150 victims in the third level institutions. We studied the necessity for the assistance in the diagnosis, recommendations for treatment, and dynamic control. We explored the effectiveness of telemedicine on the example of 110 patients. Results: The use of telemedicine technology in the process of care in patients with polytrauma is appropriate in medical institutions of the second level. There is a difference between the need and feasibility of telemedicine technology in institutions of the 2nd and the 3rd levels with the second level there is a need for treatment guidelines. The use of telemedicine technology can increase the survival of the affected by 14.5% by optimizing the provision of emergency medical care. Conclusions: Conditions of Ukraine’s health care system, do not allow providing full medical and diagnostic care in all medical institutions of Ukraine. Therefore, there is request to continue consulting practitioners in damage control specialty, dynamics of treatment, as well as providing opportunities to discuss and select the optimal therapeutic and diagnostic management

Elastic constants of borocarbides. New approach to acoustic Measurement technique

A new version of the phase method of determining the sound velocity is proposed and implemented. It utilizes the ``Nonius'' measurement technique and can give acceptable accuracy (~1%) in samples of submillimeter size. Measurements of the sound velocity are made in single-crystal samples of the borocarbides RNi2B2C (R = Y,Lu,Ho). The elastic constants and the Debye temperature are calculated.Comment: 5 figures, 2 table

Features of vascular-platelet and coagulation hemostasis in relation to parameters of macular blood fl ow in women with preeclampsia

Background. Recently, more and more attention has been paid to the development of vascular retinal disorders after suffering preeclampsia. It is noted that the key role in this process is assigned to the systemic endothelial dysfunction that persists for a long time after delivery.Aim: to elucidate the features of vascular-platelet and coagulation hemostasis in relation to the indicators of blood flow in the macular region in women with preeclampsia.Materials and methods. The main group included 45 women with preeclampsia in the third trimester of pregnancy (35–36 weeks). Their age ranged from 19 to 40 years (27 ± 5.2 years). The comparison group was represented by 20 women with physiological pregnancy in the third trimester (35–36 weeks). Their age averaged 26 ± 5.1 years (18–38 years). Somatically healthy non-pregnant women (20 people) were included in the control group. Their age ranged from 19 to 38 years (26 ± 5.4 years). A comparative analysis of the studied parameters of macular blood fl ow, vascular-platelet and coagulation hemostasis between the groups was carried out.Results. When studying the number of platelets in pregnant women, it turned out that in patients with preeclampsia, this indicator was statistically signifi cantly lower compared to the comparison and control groups (p < 0.05). The level of fi brinogen in women with complicated pregnancies was statistically significantly higher than in women with physiological pregnancy and in somatically healthy nonpregnant women (p < 0.05). In addition, retinal microcirculation disorders were observed in women of the main group.Conclusions. The revealed disorders of vascular-platelet and coagulation hemostasis in women during the period of complicated pregnancy were accompanied by disorders of macular blood fl ow in the form of a decrease in the total average density of vessels in the superfi cial vascular plexus, subfoveolar thickness of the choroid and an increase in the area of the avascular zone relative to the group of women with physiological pregnancy and somatically healthy nonpregnant women

Runaway dynamics in reactor-scale spherical tokamak disruptions

Understanding generation and mitigation of runaway electrons in disruptions is important for the safe operation of future tokamaks. In this paper we investigate runaway dynamics in reactor-scale spherical tokamaks. We study both the severity of runaway generation during unmitigated disruptions, as well as the effect that typical mitigation schemes based on massive material injection have on runaway production. The study is conducted using the numerical framework DREAM (Disruption Runaway Electron Analysis Model). We find that, in many cases, mitigation strategies are necessary to prevent the runaway current from reaching multi-megaampere levels. Our results indicate that with a suitably chosen deuterium-neon mixture for mitigation, it is possible to achieve a tolerable runaway current and ohmic current evolution. With such parameters, however, the majority of the thermal energy loss happens through radial transport rather than radiation, which poses a risk of unacceptable localised heat loads.Comment: 19 pages, 7 figure

SOLPS-ITER predictive simulations of the impact of ion-molecule elastic collisions on strongly detached MAST-U Super-X divertor conditions

The role of ion-molecule ( D+ − D2 ) elastic collisions in strongly detached divertor conditions has been studied in the MAST-U Super-X configuration using SOLPS-ITER. Two strongly detached steady state solutions were compared, one obtained through a main-ion fuelling scan and the other through a nitrogen seeding scan at fixed fuelling rate. A significant difference in the electron-ion recombination (EIR) levels was observed; significant EIR in strongly detached conditions in the fuelling scan and negligible EIR throughout the seeding scan. This is partly because the fuelling scan achieves electron temperatures ( Te ) as low as 0.2 eV near the divertor target, compared to 0.8 eV in the seeding scan (EIR increases strongly below Te ≈ 1 eV), and partly due to higher divertor plasma densities achieved in fuelling scan. Features of the strongly detached seeded cases, i.e. higher temperatures and negligible EIR, are recovered in the fuelling scan by turning off D+ − D2 elastic collisions. Analysis suggests that dissipation mechanisms like line radiation and charge exchange (important for detachment initiation) become weak when Te falls below 1 eV, and that D+ − D2 elastic collisions are necessary for further heat dissipation and access to strongly recombining conditions in the fuelling scan. In the seeding scan, heat dissipation through D+ − D2 elastic collisions is weak. This could be because our nitrogen seeding simulations do not include interactions between nitrogen ions and neutrals, and the strongly detached cases contain high levels of N+ in the divertor. As a result, the N+ acts like a reservoir of energy and momentum which appears to weaken the impact of D+ − D2 elastic collisions on the divertor plasma energy and momentum balance, making it more difficult to access recombining conditions. This suggests that some of the differences between seeding and fuelling scans could be because energy and momentum exchange between impurities and neutrals is not sufficiently captured in our simulations

Predictive SOLPS-ITER simulations to study the role of divertor magnetic geometry in detachment control in the MAST-U Super-X configuration

The SOLPS-ITER code has been utilised to study the movement of the detachment front location from target towards the X-point for MAST-U Super-X plasmas. Two sets of detached steady state solutions are obtained by either varying the deuterium (D 2) fuelling rate or the nitrogen (N) seeding rate to scan the corresponding ‘control’ parameters of outboard midplane density, n u , and the divertor impurity concentration, f I . At seeding and fuelling rates ∼10× and ∼5× that required to start detachment at the divertor target, the detachment front only reaches ∼50% of the poloidal distance to the X-point, l p o l , corresponding to a region of strong parallel gradients in the total magnetic field B. The region of strong total field gradients correlates with where the detachment front location becomes less sensitive to control parameter variation. This result is qualitatively consistent with the predictions of a simple, analytic detachment location sensitivity (DLS) model (Lipschultz et al 2016 Nucl. Fusion 56 056007) which is based in a scaled parallel-to-B space, z. While the DLS model predictions are in agreement with SOLPS-ITER results in terms of where the front location becomes less sensitive to controls (i.e. in the region of strong parallel gradients in B), the DLS model predicts a higher sensitivity in the region of weak parallel gradients in B downstream as compared to the simulation results. Potential sources of differences between the SOLPS-ITER and DLS model predictions were explored: The DLS model does not include energy sinks beyond radiation from a single impurity nor cross-field energy transport. Momentum and particle balance are also not included in the DLS model. The tight opening into the divertor for flux surfaces could lead to variations in plasma-neutral pressure balance as the detachment front reaches that region, exactly how this affects the front movement needs further investigation