Rate of steady-state reconnection in an incompressible plasma

The reconnection rate is obtained for the simplest case of 2D symmetric reconnection in an incompressible plasma. In the short note (Erkaev et al., Phys. Rev. Lett.,84, 1455 (2000)), the reconnection rate is found by matching the outer Petschek solution and the inner diffusion region solution. Here the details of the numerical simulation of the diffusion region are presented and the asymptotic procedure which is used for deriving the reconnection rate is described. The reconnection rate is obtained as a decreasing function of the diffusion region length. For a sufficiently large diffusion region scale, the reconnection rate becomes close to that obtained in the Sweet-Parker solution with the inverse square root dependence on the magnetic Reynolds number, determined for the global size of the current sheet. On the other hand, for a small diffusion region length scale, the reconnection rate turns out to be very similar to that obtained in the Petschek model with a logarithmic dependence on the magnetic Reynolds number. This means that the Petschek regime seems to be possible only in the case of a strongly localized conductivity corresponding to a small scale of the diffusion region.Comment: 11 pages, 3 figure

Ion-cyclotron turbulence and diagonal double layers in a magnetospheric plasma

A survey of current concepts regarding electrostatic ion-cyclotron turbulence (theory and experiment), and regarding inclined double potential layers in the magnetospheric plasma is presented. Anomalous resistance governed by electrostatic ion-cyclotron turbulence, and one-dimensional and two-dimensional models of double electrostatic layers in the magnetospheric plasma are examined

Ecological and Physiological Patterns of Selenium Migration within the Volga River Ecosystem

The article presents the results of selenium migration analysis within river ecosystem. Maximal concentration of selenium was observed near Tomakovsky and Nazarovsky ravines within Saratov territory. The concentration of this microelement at the right river bank was slightly higher than at the left bank. The concentration of selenium in bottom soil ranged from 0.062–0.099 μg/g. Maximal concentration of microelement was found in clasping-leaved pondweed. Selenium concentration in fish bodies depends on their species and nutrition. Maximal concentration of microelement was found in crucian carps, and minimal – in rudds

Seasonal changes of free-radical initiated processes in cyprinids from the middle Volga river basin

The purpose of this research was to study the free radical induced lipid oxidation in the commonest fish species inhabiting the Volga river, in the Middle Volga region of the Russian Federation, de-pending on the seasons of the year. The commonest fish species in the Volga river basin: European carp Cyprinus carpio (L., 1758), sabrefish Pelecus cultratus (L., 1758), common bream Abramis brama (L., 1758), tench Tinca tinca (L., 1758), and common roach Rutilus rutilus (L., 1758) were studied. The level of malondialdehyde and the activity of catalase were investigated in gills, liver, muscles and gonads. The values of molecular oxidative biomarkers in the studied fish species were significantly higher in the summer, suggestinga more active lipid peroxidation. The increase in cata-lase activity in the studied organs may indicate activation of the antioxidant defense system that can positively affect the growth and development of fish

Study of neutron energy and directional distribution at the Beloyarsk NPP selected workplaces

Energy and directional distribution of neutrons at the Beloyarsk NPP workplaces is a subject of this study. Measurements of H∗(10) rate and neutron energy distribution were taken at 8 workplaces, which can be divided into three categories: work with spent or fresh nuclear fuel, work with radionuclide neutron sources, work at the rooms adjusted to reactors. The Hp(10) measurements were performed only at 6 out of 8 locations, due to the fact that long term placing of an effective neutron moderator in fresh nuclear fuel storage facility is forbidden. As a result of the research energy and direction distribution of the neutron fields at 8 locations of the Beloyarsk NPP workplaces was obtained. To estimate the accuracy of the H∗(10) rate and Hp (10) measurements the reference values of dose equivalents were calculated using energy and directional distribution. To take into account the difference between the reference values and the measured results site-specific correction factors were calculated. © 2020 Korean Nuclear SocietyThe reported study was funded by RFBR project number 19-38-90096

Physical Background for Luminescence Thermometry Sensors Based on Pr³⁺:LaF<inf>3</inf> Crystalline Particles

© 2017 Maksim S. Pudovkin et al. The main goal of this study was creating multifunctional nanoparticles based on rare-earth doped LaF 3 nanocrystals, which can be used as fluorescence thermal sensors operating over the 80-320 K temperature range including physiological temperature range (10-50°C). The Pr 3+ :LaF 3 (CPr = 1%) microcrystalline powder and the Pr 3+ :LaF 3 (CPr = 12%, 20%) nanoparticles were studied. It was proved that all the samples were capable of thermal sensing into the temperature range from 80 to 320 K. It was revealed that the mechanisms of temperature sensitivity for the microcrystalline powder and the nanoparticles are different. In the powder, the 3 P 1 and 3 P 0 states of Pr 3+ ion share their electronic populations according to the Boltzmann and thermalization of the 3 P 1 state takes place. In the nanoparticles, two temperature dependent mechanisms were suggested: energy migration within 3 P 0 state in the temperature range from 80 K to 200 K followed by quenching of 3 P 0 state by OH groups at higher temperatures. The values of the relative sensitivities for the Pr 3+ :LaF 3 (CPr = 1%) microcrystalline powder and the Pr 3+ :LaF 3 (CPr = 12%, 20%) nanoparticles into the physiological temperature range (at 45°C) were 1, 0.5, and 0.3% °C -1 , respectively

Dissipationless Disk Accretion

We consider disk accretion resulting purely from the loss of angular momentum due to the outflow of plasma from a magnetized disk. In this limiting case, the dissipation due to the viscosity and finite electrical conductivity of the plasma can be neglected. We have obtained self-consistent, self-similar solutions for dissipationless disk accretion. Such accretion may result in the formation of objects whose bolometric luminosities are lower than the flux of kinetic energy in the ejected material.Comment: 17 pages, 6 figures, published in Astronomy Reports, Vol.49, No.1, 2005, p.57 (submitted September 13, 2003). Unfortunately, we did not upload the paper to astro-ph before, but since the topic is now of interest we feel that the paper would benefit the communit

Tiny Rare-Earth Fluoride Nanoparticles Activate Tumour Cell Growth via Electrical Polar Interactions

© 2018, The Author(s). Localised extracellular interactions between nanoparticles and transmembrane signal receptors may well activate cancer cell growth. Herein, tiny LaF3 and PrF3 nanoparticles in DMEM+FBS suspensions stimulated tumour cell growth in three different human cell lines (A549, SW837 and MCF7). Size distribution of nanoparticles, activation of AKT and ERK signalling pathways and viability tests pointed to mechanical stimulation of ligand adhesion binding sites of integrins and EGFR via a synergistic action of an ensemble of tiny size nanoparticles (< 10 nm). While tiny size nanoparticles may be well associated with the activation of EGFR, integrin interplay with nanoparticles remains a multifaceted issue. A theoretical motif shows that, within the requisite pN force scale, each ligand adhesion binding site can be activated by a tiny size dielectric nanoparticle via electrical dipole interaction. The size of the active nanoparticle stayed specified by the amount of the surface charges on the ligand adhesion binding site and the nanoparticle, and also by the separating distance between them. The polar component of the electrical dipole force remained inversely proportional to the second power of nanoparticle’s size, evincing that only tiny size dielectric nanoparticles might stimulate cancer cell growth via electrical dipole interactions. The work contributes towards recognising different cytoskeletal stressing modes of cancer cells