Chirped dissipative ion-cyclotron solitons in the Earth’s low-altitude ionospheric plasma with two ion species

Conditions for the excitation of small-scale nonlinear ion-cyclotron gradient-drift dissipative structures in cold ionospheric plasma are considered. The solution for the wave electric field in this structure in the form of a chirped soliton satisfying the equation of the Ginzburg-Landau type is derived in the electrostatic approach. The dissipative structure as a whole represents the chirped soliton accompanied by the comoving quasineutral plasma hump. The possibility of the excitation of two modes of this type (the high- and low-frequency ones) in plasma containing light and heavy ion impurities is considered. The role of electromagnetic corrections and the possible contribution introduced by these structures to the transport processes in the ionosphere are discussed.     

Photoperiodic reaction in the beet webworm Loxostege sticticalis L. (Pyraloidea, Crambidae) from eastern and western parts of its Eurasian range

The beet webworm, Loxostege sticticalis L., is a very dangerous polyphagous insect pest whose outbreaks periodically occur in southern Russia and northern China. The aim of our work was to describe the photoperiodic response of beet webworm populations from western (Krasnodar Territory and Rostov Province) and eastern [Buryatia and China (Hebei Province)] parts of the pest range. The insects were reared under constant photoperiods of 12–18 h and constant temperatures of 19–25°C. Incidence of diapause at different photoperiods did not show any considerable geographic differences, and the critical day length at which 50% of prepupae arrested their development was about 14–15 h in all the populations studied at experimental temperatures. The results obtained agree with the hypothesis on the existence of an area (or areas) where the pest survives during adverse periods and wherefrom it spreads when an outbreak begins (Saulich et al., 1983; Goryshin et al., 1986). Presumably, the larger part of the pest native habitats (to the north of the steppe zone) is occupied by temporary populations, incapable of surviving for long periods without an inflow of migrants from more southerly steppe regions.     

Study of regulation of some key enzymes of L-alanine biosynthesis by Brevibacterium Flavum producer strains

The mechanisms of L-alanine overproduction by Brevibacterium flavum strain-producers were studied. It was shown that β-Cl-L-alanine is an inhibitor of some key enzymes involved in the synthesis of L-alanine: alanine transaminase and valine-pyruvate transaminase. Two highly active B. flavum GL1 and GL18 strain-producers, which are resistant to the inhibitory effect of β-Cl-L-alanine, were obtained using a parental B. flavum AA5 strain-producer, characterized by a reduced activity of alanine racemase (≥98%). It was demonstrated that the increased L-alanine synthesis efficiency observed in the strain-producer developed in this work is associated with the absence of inhibition of alanine transaminase by the end product of the biosynthesis reaction, as well as with the effect of derepression of both alanine transaminase and valine-pyruvate transaminase synthesis by the studied compound.     

Two populations of pluripotent stem cells in planarians <Emphasis Type="Italic">Girardia tigrina</Emphasis>

The positional differences in the regenerative capability of individual body parts of the planarian Girardia (Dugesia) tigrina were analyzed. The paper shows the significance of the size and positional differences of individual fragments of planarians for their regenerative capabilities, as well as the fundamental difference in the mechanisms of the head and tail blastema formation. A scheme of regeneration that includes two populations of pluripotent stem cells called neoblasts is suggested. The two populations of neoblasts differ in their role and distribution along the planarian body. Specifically, the population of neoblasts involved in the formation of any blastema migrates to the nearest blastema, and the population participating only in the creation of the head blastema migrates along the planarian body, following the gradient of biomass of the damaged axons arising after the amputation of the head end. The maximal size of the head blastema was found in the fragment obtained after cutting off the head fragment at the eye level, and the maximal portion of all pluripotent stem cells migrating into two blastemas was found in the fragment obtained by cutting the planarian above the mouth, followed by cutting off the head fragment at the eye level.     

Horizontal distribution of the cell abundance and toxicity of <Emphasis Type="Italic">Microcystis</Emphasis> in a hypereutrophic Moroccan reservoir

The first results of the horizontal distribution of the cell abundance and toxicity of Microcystis in the hypereutrophic Moroccan reservoir Lalla Takerkoust are reported. An unexpected spatio-temporal heterogeneity has been shown between Microcystis abundance and microcystins concentrations. The principal determining factors were analyzed in order to identify the most likely sites for the proliferation and/or accumulation of Microcystis in this reservoir. The horizontal heterogeneity seems to be mainly influenced by the wind direction and inflows. The results can serve as reference data for monitoring cyanobacterial water blooms and associated cyanotoxins in the lake.     

Development of nanostructured phosphorite: Study of the safety of application

A nanostructured mineral food supplement with a particle size of 60.0–120.0 nm was manufactured from phosphorite by ultrasonic dispersion. It was found that intragastric administration of nanostructures phosphorite to mice is relatively safe: clinical signs of intoxication appeared after a single administration of the preparation only at a dose of 90 mg/kg; a dose of 150 mg/kg caused death of 8% of mice, in which injuries of organs of the gastrointestinal tract were observed. When the preparation was administered subcutaneously, intramuscularly, or intraperitoneally, small phosphorite conglomerates and inflammation of the surrounding tissues and organs were observed at the injection site. Death of 25% of animals was observed in the group of mice which received intraperitoneal injections of nanophosphorite at a dose of 200 mg/kg.     

Feeding of benthophagous fish in the Chogray Reservoir

Data on feeding of the bream Abramis brama, roach Rutilus rutilus, and white bream Blicca bjoerkna in Chogray Reservoir in 2010 and 2012 are presented. The main diet of bream consists of Chironomidae, and the diet of roach and white bream consists of the bivalve mollusk Dreissena polymorpha.     

Amplitude−temporal characteristics of a supershort avalanche electron beam generated during subnanosecond breakdown in air and nitrogen

The amplitude?temporal characteristics of a supershort avalanche electron beam (SAEB) with an amplitude of up to 100 A, as well as of the breakdown voltage and discharge current, are studied experimentally with a picosecond time resolution. The waveforms of discharge and SAEB currents are synchronized with those of the voltage pulses. It is shown that the amplitude?temporal characteristics of the SAEB depend on the gap length and the designs of the gas diode and cathode. The mechanism for the generation of runaway electron beams in atmospheric-pressure gases is analyzed on the basis of the obtained experimental data.     

Some features of horizontally oriented low-current electric arc in air

The properties of an electric arc operating in open air at currents of lower than 1 A were studied experimentally. The rod cathode was oriented horizontally. Cylindrical rods and plane plates either installed strictly vertically in front of the cathode end or tilted at a certain angle served as the anode. It is shown that, with such an electrode configuration, it is possible to form a discharge channel much longer than the electrode gap length. Regimes of regular oscillations are revealed, and conditions for their appearance are established. The electric field strength in the arc column and the electron temperature near the anode are calculated.     

Characteristics of X-ray Emission from a Micropinch Discharge at Different Polarities of the Discharge Electrodes

Plasma Physics Reports - The measurement technique and results are presented from studies of the X-ray spectra and X-ray yield from micropinch discharge plasma in a low-inductive vacuum spark...