We consider interaction of a high-energy electron beam with superstrong laser pulses. Nonlinear Compton scattering and electron–positron pair production by the emitted photons result in development ...of an electromagnetic “shower-type” cascade, which however collapses rather quickly due to energy losses by secondary particles. Nevertheless, the laser field accelerates the slowed down electrons and positrons, thus giving rise to development of electromagnetic cascade of another type (“avalanche-type”). This effect of cascade collapse and revival can be observed at the electron beam energy of the order of several GeV and laser pulses intensity ∼1024 W/cm2. This means that it can be readily observed at the novel laser facilities which are either planned for the nearest future, or are already under construction. The proposed experimental setup provides the most realistic and promissory way to observe the “avalanche-type” cascades.
•Interaction of laser pulse with electrons may result in QED cascades of two types.•Both of them can occur when high-energy electrons collide with intense laser pulses.•We predict the effect of collapse and revival of QED cascade in collision experiment.•The effect can be observed at laser facilities which are under construction.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Optically detected electron spin resonance in fiber-coupled nitrogen-vacancy (NV) centers of diamond is used to demonstrate a fiber-optic quantum thermometry of individual thermogenetically activated ...neurons. Laser-induced temperature variations read out from single neurons with the NV-diamond fiber sensor are shown to strongly correlate with the fluorescence of calcium-ion sensors, serving as online indicators of the inward Ca
current across the cell membrane of neurons expressing transient receptor potential (TRP) cation channels. Local laser heating above the TRP-channel activation threshold is shown to reproducibly evoke robust action potentials, visualized by calcium-ion-sensor-aided fluorescence imaging and detected as prominent characteristic waveforms in the time-resolved response of fluorescence Ca
sensors.
We report that normal incidence transmission of circularly polarized waves through the lossy anisotropic planar chiral structure is asymmetric in the opposite direction. The new effect is ...fundamentally distinct from conventional gyrotropy of bulk chiral media and the Faraday effect, where the eigenstates are a pair of counterrotating elliptical states, while the eigenstates of the lossy anisotropic planar chiral structure are two corotating elliptical polarizations.
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A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was proposed. In the proposed model, the engineering coefficients ...of localization of total strains (LTS coefficients) are considered instead of the classical strain localization tensors. For a pore, these coefficients represent the ratio of the sum of the strains in the volume of the pore to the sum of the strains in the volume of the porous body. To estimate the elastic moduli of a material with an arbitrary pore size, it is sufficient to have information about the elastic moduli and the LTS coefficient of a material with one basic pore size. Then, in Eshelby’s model of equivalent inclusion, a transition to LTS coefficient for material with arbitrary pore size is achieved, and its elasticity moduli are determined. The results for Young’s modulus of porous titanium, with different sizes of spherical pores, completely conform with the experimental data. We have obtained a model theoretic estimate of the upper bounds of Young’s modulus of porous materials with infinitely small pore size. For the spherical pores, the proposed assessment coincides with the upper limits of the Hashin–Shtrikman bounds.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Different approaches to correction of the ECG signal baseline drift are compared. A new adaptive method for correction of the baseline drift is proposed. The method is based on shaping the reference ...signal of the adaptive filter using multiresolution wavelet transforms of the ECG signal. Different baseline drift correction methods are compared in terms of their efficiency for processing model ECG signals contaminated by baseline drift of various intensities. The accuracy of determining the ST-segment deviation in real ECG signals using different methods for the baseline drift correction is assessed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
This article describes the process of formation of clear interfaces between the components of a multilayer nanocomposite. Experimental studies and modeling show that the quality of the interface ...noticeably deteriorates with an increase in the number of layers, which is associated with the accumulation of defects and an increase in their size on the surface of each subsequently deposited nanolayer of a multilayer system. Preparation or modernization of the surface, on which the atoms of the next layer of the nanosystem are deposited to improve its quality, has a positive effect on the formation of a high-quality interface between the layers. The article considers a method of surface modernization such as pressing. The modified embedded atom method (MEAM) is used as a method for studying the structure and relief of the surface. The computational experiment has been carried out using molecular dynamics simulation. The LAMMPS software package is used in the simulation. The simulation of pressing the substrate, which makes it possible to improve the interface of the nanosystem, and of deposition of the nanofilm are carried out. The simulation of deposition is performed in a stationary temperature regime. The computational experiment is carried out with five temperature regimes: 300, 250, 200, 100, and 50 K. The effectiveness of the proposed technique is analyzed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
One of the key goals in the overhead power lines at the isolated neutral system 6–10–35 kV is topographic search area limitation for a single phase-to-ground (SPG) fault. This will ensure reliability ...improvement warranty and continuity of power supply. No fault founded in time can lead to failure of electrical equipment. Faults can initiate a ground fire in dry-weather period, which requires preventive shutdown of power lines with subsequent economic damage to power supply organizations. The paper proposes the use of emergency mode parameters, namely, zero-sequence voltages, in order to determine the faults locations in a calculated way. The need for additional installation of measuring voltage transformers at terminal substations is associated with some financial costs. In this regard, the possibility of their limited use is being considered. It has been shown that in this case the emergency section can be localized with accuracy down to the tap if there are no measuring voltage transformers on it. To calculate the SPG location, a mathematical model of lines with distributed parameters has been used. Signals at higher harmonics (HH) generated in the electrical network by arc faults, are considered useful. Full-scale experiments show the HH presence also during electrical contacts of wires with metal structures. The high frequency of the signal causes a significant change in voltage along the length of the line, which increases the accuracy of calculations. The use of zero sequence voltages promotes detuning from the influence of substation load. An algorithm has been developed for performing calculations to determine the location/area with a ground protection zone on a tree-structure feeder.
We demonstrate a robust, all-solid-state approach for the generation of microjoule subcycle pulses in the midinfrared through a cascade of carefully optimized parametric-amplification, ...difference-frequency-generation, spectral-broadening, and chirp-compensation stages. This method of subcycle waveform generation becomes possible due to an unusual, ionization-assisted solid-state pulse self-compression dynamics, where highly efficient spectral broadening is enabled by ultrabroadband four-wave parametric amplification phase matched near the zero-group-velocity wavelength of the material.
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