Roton dipole moment

The roton excitation in the superfluid He-4 does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorption line at roton frequency under external electric field.Comment: 5 page

CLIMATIC FACTORS CHARACTERIZING THE MOISTURE SUPPLY OF THE TERRITORY AND THEIR EFFECT ON THE QUALITY INDICATORS OF GRAPES

The study of scientific problem, to which this research is devoted, is due to planetary climate change, manifested in an increase in the average annual air temperature, rapid changes in winter and summer temperatures, and a lack of precipitation. For today, there is a serious problem of adapting plants to climate change due to an increase in water deficiency in many regions of the world. Climate change creates significant uncertainty in the potential adaptability of grape plants, as well as in the prospects for viticulture development in general. The study and generalization of territorial distribution of climatic factors that characterize a particular region, as well as their effect on the quality characteristics of raw materials and finished products, are attractive from the point of better understanding and forecasting the potential impact on agricultural systems. The obtained data consumption will allow improving the forecast of climate change consequences in the medium term, and in relation to particular terroirs. The goal is to study the effect of climatic factors that characterize the moisture supply of the territory on the quality indicators of grapes. Materials and methods. The objects of the study were grapes of white and red cultivars, different in agroecological aspect, and growing in micro regions of Crimea. To identify the effect of factors characterizing the moisture supply of the territory on the quality indicators of raw materials for winemaking products, the amount of precipitation from the beginning of growing season to the harvesting, the amount of precipitation for the last month before harvest, and hydrothermal coefficient of Selyaninov were selected. The assessment of grapes was carried out according to the indicators of carbohydrate-acid complex (mass concentration of sugars, titratable acids, pH value, profile of organic acids), as well as the glucoacidimetric indicator revealing the degree of grape ripeness. Results and conclusion. Climatic factors characterizing the moisture supply of viticultural and winemaking regions of Crimea were assessed. The studies carried out made it possible to reveal variations in the concentration of carbohydrate-acid complex components depending on the changing ability of environmental factors. A significant precipitation deficiency was observed on the Peninsula. According to the value of hydrothermal coefficient of Selyaninov (did not exceed 1), most of the territory was classified as an arid or very arid zone. A correlation between the hydrothermal coefficient and mass concentration of grape sugars (r=-0.63) was established for red grapevine cultivars. The data obtained indicate that an increase in the amount of precipitation during growing season contributes to a moderation of sugar accumulation in grapes. Similar pattern was not established for white grapevine cultivars. There was a direct correlation of the mass concentration of malic acid on the amount of precipitation in the last month before harvest (r=0.78)

Change of Parameters of the Koiwa–Hasiguti Dynamic Dislocation Relaxation in Nanostructured and Polycrystalline Zirconium after Severe Plastic Deformation and Annealing

The temperature dependences of acoustic properties of nanostructured and polycrystalline zirconium are investigated in the temperature range of 100–340 K. The effect of severe plastic deformation and subsequent annealing on key parameters of the Koiwa–Hasiguti acoustic relaxation in zirconium is studied in detail. It is established that, due to intensive plastic deformation, the relaxation strength considerably increases, and the temperature and the width of the corresponding relaxation peak systematically decrease with reduction of the mean grain size in the samples. Annealing leads to a partial recovery of the relaxation strength and the peak temperature back to the initial values in undeformed samples, but the width of the relaxation peak shows an additional decrease. The majority of the effects observed can be explained by changes in dislocation subsystems of the samples during intensive plastic deformation and annealing. An influence of a random scatter of the relaxation time on the main parameters of the Koiwa–Hasiguti peak is established using the statistical analysis based on the lognormal distribution. It is shown that the parameter β of the lognormal distribution determines the width, height, and asymmetry of the peak and also allows estimating the relaxation strength from the peak height. An algorithm for retrieving the parameter β from experimental data is presented

Effect of pulse flows of charged particles on the structure and mechanical properties of metals

We investigate the effect of pulse flows of hydrogen, helium, and hydrogen-helium plasma of a specific power of 20-30 GW/m² on the surface structure and mechanical properties of vanadium, niobium, and Kh16N15M3B and Kh18N10T austenitic stainless steelsyesBelgorod State Universit

On the electric activity of superfluid systems

The Keldysh's theory of superfluidity of rarefied electron-hole gas is generalized to a case of possible pair polarizability. It was shown that inhomogeneity of the system leads to dipole moment which is proportional to the density gradient. The dipole moment appears also near boundaries of the system. It was determined that quantized vortices in a magnetic field carry a real electric charge. In He II at H=10 T and helium rotation velocity $10^2$ s$^{-1}$ the charge density is about $10^4e$ cm$^{-3}$, where $e$ is the electron charge.Comment: 5 pages V. 2: replaced incorrect g valu

Current approaches to antithrombotic therapy in patients with cardioembolic stroke

The rate of cardiogenic embolism among all ischemic strokes is as high as 38%. Cardioembolic strokes are characterized by the higher magnitude of neurological deficit, the high risk of recurrent acute stroke, and a lethal outcome. This review deals with the etiopathogenesis of thrombus formation in the heart chambers, with current criteria for the verification of cardioembolic strokes, with the results of trials of new oral anticoagulants, and latest guidelines for antithrombotic therapy to prevent stroke. Special focus is given to secondary stroke prevention in patients with nonvalvular atrial fibrillation since it is atrial fibrillation that is the most common cause of cardioembolic stroke