Індекс рубрикатора НБУВ: Е621.143 + Е0*836

Рубрики:

Nemathelminthes Первиннопорожнинні черви

Загальна біологія

Шифр НБУВ: Ж27025 Пошук видання у каталогах НБУВ 

Ключ. слова: Plathelminthes, Monogenea, Gyrodactylidae, Kamchatka, Gasterosteus aculeatus, Gyrodactylus alexanderi
Індекс рубрикатора НБУВ: Е621.141.5(051)

Шифр НБУВ: Ж27025 Пошук видання у каталогах НБУВ 

The energies of first two subbands are calculated, within a variational approach, for electrons localized over the surface of a liquid-helium film covering a solid substrate. The results are obtained for arbitrary value of the dielectric constant of the solid substrate, covering both the limit of a substrate with a dielectric constant close to unity (such as a rare gas solid) and a metal. The results for the subband energies for a metallic substrate are compared with those obtained previously by a different method by Gabovich, Ilchenko, and Pashitskii. The agreement is rather good supporting the applicability of the variational method for calculating the energy spectrum of surface electrons in a wide range of substrate parameters.

The low temperature bound of the decay rate of the excited surface electron states on liquid helium is theoretically studied. It is shown that the lifetime and dephasing time of the surface electron states are strongly limited by spontaneous emission of couples of short-wavelength capillary wave quanta (ripplons). These two-ripplon scattering processes are of the second order in the nonlinear interaction Hamiltonian. In contrast to the usual one-ripplon scattering contribution, the decay rate found here cannot be substantially reduced neither by lowering temperature nor by external magnetic field, which is important for recently discussed implementation of quantum bits in such a system.

Індекс рубрикатора НБУВ: В368.32

Рубрики:

Фізика рідкого гелію

Шифр НБУВ: Ж14063 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В368.32

Рубрики:

Фізика рідкого гелію

Шифр НБУВ: Ж14063 Пошук видання у каталогах НБУВ 

We present experimental data and a theoretical analysis of nonequilibrium mobility of surface electrons in liquid helium. The experiments are carried out in the temperature range where electron mobility is limited by electron scattering at surface excitations of liquid helium (ripplons). Holding and driving electric fields of wide ranges are used in measurements. Special attention is paid to the condition of strong holding fields under which hot electrons are confined to the ground surface level. Depending on the relation between the momentum relaxation rate and electron-electron collision frequency, different theoretical approaches are used to describe the nonlinear mobility of surface electrons. The results obtained allow to estimate the range of physical parameters where experimental data can be described by the theory of nonlinear electron transport within the ground surface level.

The influence of van der Waals forces on the decay of liquid solutions of helium isotopes is studied theoretically and the conditions for the phase co-existence in a confined geometry are investigated. As the models to account the influence of van der Waals forces on the helium isotope solution the gap between two parallel planes and the cylindrical channel are considered. For each of the models we calculated the concentration profile inside the channel depending on the van der Waals constant, the initial solution concentration and the size of the channel. The phase diagrams of liquid solutions are constructed. The obtained liquid mixture phase diagrams are compared with the "bulk" phase diagram. A rather good agreement between theoretical and experimental phase diagrams is obtained for liquid helium mixture in aerogel.

Розглянуто сучасні методи та засоби вирішення завдання розрахунку напружено-деформованого стану (НДС) палубних елементів суден. Проаналізовано сучасні методи оцінювання НДС суднових пластин на стадії проектування та експлуатації судна. Для цього розглянуто основні програмні комплекси, що надають можливість проводити подібні розрахунки, їх переваги та недоліки. Наведено основні етапи створення програмного забезпечення для проведення розрахунків, заснованих на використанні системи Кармана.

We synthesized the general structures of biomedical electric impedance biotechnical systems as a part of cyber-physical systems and propose methodological recommendations on the electric impedance equipment development.

Індекс рубрикатора НБУВ: В371.59

Шифр НБУВ: Ж43925 Пошук видання у каталогах НБУВ 

Індекс рубрикатора НБУВ: В368.321

Рубрики:

Надплинність

Шифр НБУВ: Ж14063 Пошук видання у каталогах НБУВ 

The simulation of a system of particles, located in the plane, with van der Waals interaction described by the Lennard-Jones potential is carried out. The possibility of the existence of a solitary chain of particles, as well as the formation of linear systems of two and three chains, has been established. The spectrum of vibrations of the systems was determined for various configurations and the characteristic frequencies of the vibrations were found. The dispersion law of collective modes is calculated theoretically by the method of equations of motion for small displacements of atoms from their equilibrium position when analyzing the compatibility condition for the arising system of equations. The obtained values of the characteristic frequencies are in rather good agreement with the results obtained in the Fourier analysis of the time dependence of the displacements of particles from their equilibrium positions along and across the system.

From the experimental point of view, the works on the study of the so-called electrical activity in superfluid helium are analyzed. Based on the analysis of published data on the results of experiments on the appearance of such electrical activity under the propagation of second sound waves, during oscillations of a torsion oscillator filled with helium and microwave electromagnetic pumping of helium, one concludes that the experimental results published before 2016 do not give sufficient reasons to assume the presence of any special electrical activity of helium, and the appearance of an electric signal in a cell with superfluid helium at the propagation of acoustic waves in it can only be said after 2016. The nature of this signal needs further investigation.

Індекс рубрикатора НБУВ: П082.62

Рубрики:

Теплиці

Шифр НБУВ: Ж101239 Пошук видання у каталогах НБУВ