1,379 research outputs found
Can We Apply Statistical Laws to Small Systems? the Cerium Atom
It is shown that statistical mechanics is applicable to quantum systems with
finite numbers of particles, such as complex atoms, atomic clusters, etc.,
where the residual two-body interaction is sufficiently strong. This
interaction mixes the unperturbed shell-model basis states and produces
``chaotic'' many-body eigenstates. As a result, an interaction-induced
equilibrium emerges in the system, and temperature can be introduced. However,
the interaction between the particles and their finite number can lead to
prominent deviations of the equilibrium occupation numbers distribution from
the Fermi-Dirac shape. For example, this takes place in the cerium atom with
four valence electrons, which was used to compare the theory with realistic
numerical calculations.Comment: 4 pages, Latex, two figures in eps-forma
Volume discharge in a gas, excited by an electron beam under conditions of nonuniform ionization
Volume discharge in gases excited by electron beams is discussed. The steady state electric field distribution is derived. The voltage-current and energy characteristics are described
Gamow-Teller strength distributions at finite temperatures and electron capture in stellar environments
We propose a new method to calculate stellar weak-interaction rates. It is
based on the Thermo-Field-Dynamics formalism and allows the calculation of the
weak-interaction response of nuclei at finite temperatures. The thermal
evolution of the GT distributions is presented for the sample nuclei Fe and ~Ge. For Ge we also calculate the strength distribution
of first-forbidden transitions. We show that thermal effects shift the GT
centroid to lower excitation energies and make possible negative- and
low-energy transitions. In our model we demonstrate that the unblocking effect
for GT transitions in neutron-rich nuclei is sensitive to increasing
temperature. The results are used to calculate electron capture rates and are
compared to those obtained from the shell model.Comment: 16 pages, 9 figure
Investigation of LiFeAs by means of "Break-junction" Technique
In our tunneling investigation using Andreev superconductor - normal metal -
superconductor contacts on LiFeAs single crystals we observed two reproducible
independent subharmonic gap structures at dynamic conductance characteristics.
From these results, we can derive the energy of the large superconducting gap
meV and the small gap meV at
K for the K (the contact area
critical temperature which deviation causes the variation of ). The
BCS-ratio is found to be , whereas
results from induced superconductivity in the bands
with the small gap.Comment: 7 pages, 5 figures. Published in Pis'ma v ZhETF 95, 604-610 (2012
Role of Russia in peaceful settlement of the conflict of North and South Korea: event analysis
This study analyzes the conflict between North Korea and South Korea. The Russian Federation has played an important role in the peaceful settlement of this conflict, which has an impact on the formation of the appearance of Russia in the international arena. The theoretical basis of the study was the theory of images, communication and international conflicts. Using the eventanalysis method, an event-based picture of the conflict was built, comparative assessments were made, conflicting parties, indirect participants and intermediaries were identified. An analysis of the current situation is given, groups of interests and the role of Russia in the peaceful settlement of this conflict are identified.Este estudio analiza el conflicto entre Corea del Norte y Corea del Sur. La Federación de Rusia ha desempeñado un papel importante en la solución pacífica de este conflicto, que tiene un impacto en la formación de la aparición de Rusia en la arena internacional. La base teórica del estudio fue la teoría de las imágenes, la comunicación y los conflictos internacionales. Utilizando el método de análisis de eventos, se construyó una imagen del conflicto basada en eventos, se realizaron evaluaciones comparativas, se identificaron las partes en conflicto, los participantes indirectos y los intermediarios. Se presenta un análisis de la situación actual, se identifican los grupos de intereses y el papel de Rusia en la solución pacífica de este conflicto.Este estudo analisa o conflito entre a Coréia do Norte e a Coréia do Sul. A Federação Russa tem desempenhado um papel importante na solução pacífica deste conflito, que tem um impacto sobre a formação da aparição da Rússia na arena internacional. A base teórica do estudo foi a teoria das imagens, comunicação e conflitos internacionais. Usando o método de análise de eventos, uma imagem baseada em eventos do conflito foi construída, avaliações comparativas foram feitas, partes conflitantes, participantes indiretos e intermediários foram identificados. Uma análise da situação atual é dada, grupos de interesses e o papel da Rússia na solução pacífica deste conflito são identificados
Anharmonic properties of double giant dipole resonance
A systematic microscopic study of the anharmonic properties of the double
giant dipole resonance (DGDR) has been carried out, for the first time, for
nuclei with mass number spanning the whole mass table. It is concluded that
the corrections of the energy centroid of the and
components of the DGDR from its harmonic limit are negative, have a value of
the order of few hundred keV and follow an dependence.Comment: 4 pages, 2 figure
Lagrangian structures in time-periodic vortical flows
The Lagrangian trajectories of fluid particles are experimentally studied in an oscillating four-vortex velocity field. The oscillations occur due to a loss of stability of a steady flow and result in a regular reclosure of streamlines between the vortices of the same sign. The Eulerian velocity field is visualized by tracer displacements over a short time period. The obtained data on tracer motions during a number of oscillation periods show that the Lagrangian trajectories form quasi-regular structures. The destruction of these structures is determined by two characteristic time scales: the tracers are redistributed sufficiently fast between the vortices of the same sign and much more slowly transported into the vortices of opposite sign. The observed behavior of the Lagrangian trajectories is quantitatively reproduced in a new numerical experiment with two-dimensional model of the velocity field with a small number of spatial harmonics. A qualitative interpretation of phenomena observed on the basis of the theory of adiabatic chaos in the Hamiltonian systems is given. <br><br> The Lagrangian trajectories are numerically simulated under varying flow parameters. It is shown that the spatial-temporal characteristics of the Lagrangian structures depend on the properties of temporal change in the streamlines topology and on the adiabatic parameter corresponding to the flow. The condition for the occurrence of traps (the regions where the Lagrangian particles reside for a long time) is obtained
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